## Publications

Download my list of publications (last update: July 2017).

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- Journals (with abstracts)
- Edited books
- Book chapters
- Stand-alone videos (in conference proceedings)
- Conferences

### Journals

[J-49] S. Haddadin, A. De Luca, A. Albu-Schäffer "**Robot collisions: A survey on detection, isolation, and identification**,"

*IEEE Transactions on Robotics*, vol. PP, no. 99, pp. tbd, 2017 [on-line since 5 Oct 2017] (pdf)

Robot assistants and professional coworkers are becoming a commodity in domestic and industrial settings. In order to enable robots to share their workspace with humans and physically interact with them, fast and reliable handling of possible collisions on the entire robot structure is needed, along with control strategies for safe robot reaction. The primary motivation is the prevention or limitation of possible human injury due to physical contacts. In this survey paper, based on our early work on the subject, we review, extend, compare, and evaluate experimentally model-based algorithms for real-time collision detection, isolation, and identification that use only proprioceptive sensors. This covers the context-independent phases of the collision event pipeline for robots interacting with the environment, as in physical humanâ€“robot interaction or manipulation tasks. The problem is addressed for rigid robots first and then extended to the presence of joint/transmission flexibility. The basic physically motivated solution has already been applied to numerous robotic systems worldwide, ranging from manipulators and humanoids to flying robots, and even to commercial products. DOI:10.1109/TRO.2017.2723903

[J-48] M. Maisto, C. Pacchierotti, F. Chinello. G. Salvietti, A. De Luca, D. Prattichizzo "

**Evaluation of wearable haptic systems for the fingers in Augmented Reality applications**,"

*IEEE Transactions on Haptics*, vol. PP, no. 99, pp. tbd, 2017 [on-line since 5 Apr 2017] (pdf) [multimedia]

Although Augmented Reality (AR) has been around for almost five decades, only recently we have witnessed AR systems and applications entering in our everyday life. Representative examples of this technological revolution are the smartphone games "Pokémon GO" and "Ingress" or the Google Translate real-time sign interpretation app. Even if AR applications are already quite compelling and widespread, users are still not able to physically interact with the computer-generated reality. In this respect, wearable haptics can provide the compelling illusion of touching the superimposed virtual objects without constraining the motion or the workspace of the user. In this paper, we present the experimental evaluation of two wearable haptic interfaces for the fingers in three AR scenarios, enrolling 38 participants. In the first experiment, subjects were requested to write on a virtual board using a real chalk. The haptic devices provided the interaction forces between the chalk and the board. In the second experiment, subjects were asked to pick and place virtual and real objects. The haptic devices provided the interaction forces due to the weight of the virtual objects. In the third experiment, subjects were asked to balance a virtual sphere on a real cardboard. The haptic devices provided the interaction forces due to the weight of the virtual sphere rolling on the cardboard. Providing haptic feedback through the considered wearable device significantly improved the performance of all the considered tasks. Moreover, subjects significantly preferred conditions providing wearable haptic feedback. DOI:10.1109/TOH.2017.2691328

[J-47] F. Flacco, A. De Luca "

**Real-time computation of distance to dynamic obstacles with multiple depth sensors**,"

*IEEE Robotics and Automation Letters*, vol. 2, no. 1, pp. 56-63, 2017 [on-line since 29 Feb 2016] (pdf) [multimedia]

We present an efficient method to evaluate distances between dynamic obstacles and a number of points of interests (e.g., placed on the links of a robot) when using multiple depth cameras. A depth-space oriented discretization of the Cartesian space is introduced that represents at best the workspace monitored by a depth camera, including occluded points. A depth grid map can be initialized off line from the arrangement of the multiple depth cameras, and its peculiar search characteristics allows fusing on line the information given by the multiple sensors in a very simple and fast way. The real-time performance of the proposed approach is shown by means of collision avoidance experiments where two Kinect sensors monitor a human-robot coexistence task. DOI:10.1109/LRA.2016.2535859

[J-46] G. Buondonno, A. De Luca "

**Efficient computation of inverse dynamics and feedback linearization for VSA-based robots**,"

*IEEE Robotics and Automation Letters*, vol. 1, no. 2, pp. 908-915, 2016 [on-line since 5 Feb 2016] (pdf) [multimedia]

We develop a recursive numerical algorithm to compute the inverse dynamics of robot manipulators with an arbitrary number of joints, driven by Variable Stiffness Actuation (VSA) of the antagonistic type. The algorithm is based on Newton-Euler dynamic equations, generalized up to the fourth differential order to account for the compliant transmissions, combined with the decentralized nonlinear dynamics of the variable stiffness actuators at each joint. A variant of the algorithm can be used also for implementing a feedback linearization control law for the accurate tracking of desired link and stiffness trajectories. As in its simpler versions, the algorithm does not require dynamic modeling in symbolic form, does not use numerical approximations, grows linearly in complexity with the number of joints, and is suitable for on-line feedforward and real-time feedback control. A Matlab/C code is made available. DOI:10.1109/LRA.2016.2526072

[J-45] H. Wang, F. Patota, G. Buondonno, M. Haendl, A. De Luca, K. Kosuge "

**Stability and variable admittance control in the physical interaction with a mobile robot**,"

*International Journal of Advanced Robotic Systems*, vol. 12:173, pp. 1-14, 2015 [open access] [on-line since 8 Dec 2015] (pdf)

Admittance controllers have been widely implemented in physical human-robot interaction (pHRI). The stability criteria and the parameter adaptation methods for admittance control have been well studied. However, the established methods were mainly focused on human-manipulator interactions, and cannot be directly extended to the mobile-robot-based pHRI, in which the nonlinearity cannot be canceled by feedback linearizations, and the measurements of the relative human/robot position and orientation are usually lacking. In this paper, we study the pHRI between a human user and a mobile robot under admittance control. We developed a robotic system which can measure the relative chest/ankle positions of the human user with respect to the robot. Using the measured human position, a human-frame admittance controller is proposed to remove the nonlinearity in system dynamics. Based on the human-frame admittance control, a stability criterion is derived. By using a human-arm stiffness estimator along with the derived stability criterion, a stiffness-based variable admittance controller is designed. The effectiveness of the proposed methods in improving the pHRI performance is tested and supported by simulation and experiment results. DOI:10.5772/61237

[J-44] F. Flacco, A. De Luca, O. Khatib, "

**Control of redundant robots under hard joint constraints: Saturation in the null space**,"

*IEEE Transactions on Robotics*, vol. 31, no. 3, pp. 637-654, June 2015 [on-line since 28 Apr 2015] (pdf) [multimedia], Young Author Best Paper Award 2016 by the IEEE RAS Italian Chapter.

We present an efficient method for addressing online the inversion of differential task kinematics for redundant manipulators, in the presence of hard limits on joint space motion that can never be violated. The proposed SNS (Saturation in the Null Space) algorithm proceeds by successively discarding the use of joints that would exceed their motion bounds when using the minimum norm solution. When processing multiple tasks with priority, the SNS method realizes a preemptive strategy by preserving the correct order of priority in spite of the presence of saturations. In the single- and multi-task case, the algorithm automatically integrates a least possible task scaling procedure, when an original task is found to be unfeasible. The optimality properties of the SNS algorithm are analyzed by considering an associated Quadratic Programming problem. Its solution leads to a variant of the algorithm, which guarantees optimality also when the basic SNS algorithm does not. Numerically efficient versions of these algorithms are proposed. Their performance allows real-time control of robots executing many prioritized tasks with a large number of hard bounds. Experimental results are reported. DOI:10.1109/TRO.2015.2418582

[J-43] F. Flacco, A. De Luca, "

**Discrete-time redundancy resolution at the velocity level with acceleration/torque optimization properties**,"

*Robotics and Autonomous Systems*, vol. 70, pp. 191-201, August 2015 [on-line since 4 Mar 2015] (pdf) [multimedia]

With reference to robots that are redundant for a given task, we present a novel and intuitive approach allowing to define a discrete-time joint velocity command that shares the same characteristics of a second-order inverse differential scheme, with specified properties in terms of joint acceleration or torque. Our main goal is to show how commands in the null space of the task can yield different locally optimal solutions, working only at the velocity control level. By following our general method, it is possible to obtain simple implementations of possibly complex robot control laws that *i)* can be directly interfaced to the low-level servo loops of a robot, *ii)* require less task information and on-line computations, *iii)* are still provably good with respect to some target performance. The method is illustrated by considering the conversion into discrete-time velocity commands of control schemes for redundant robots that minimize the (weighted and/or biased) norm of joint acceleration or joint torque. The approach can be extended to auxiliary tasks, possibly organized with priority. Numerical simulations and experimental results are presented for the control of a 7R KUKA LWR IV robot. DOI:10.1016/j.robot.2015.02.008

[J-42] F. Flacco, T. Kröger, A. De Luca, O. Khatib, "

**A depth space approach for evaluating distance to objects -- with application to human-robot collision avoidance**,"

*Journal of Intelligent & Robotic Systems*(Special Issue on Cognitive Robotics Systems: Concepts and Applications), vol. 80, suppl. 1, pp. 7-22, December 2015 [on-line since 24 Oct 2014] (pdf) [multimedia]

We present a novel approach to estimate the distance between a generic point in the Cartesian space and objects detected with a depth sensor. This information is crucial in many robotic applications, e.g., for collision avoidance, contact point identification, and augmented reality. The key idea is to perform all distance evaluations directly in the depth space. This allows distance estimation by considering also the frustum generated by the pixel on the depth image, which takes into account both the pixel size and the occluded points. Different techniques to aggregate distance data coming from multiple object points are proposed. We compare the Depth space approach with the commonly used Cartesian space or Configuration space approaches, showing that the presented method provides better results and faster execution times. An application to human-robot collision avoidance using a KUKA LWR IV robot and a Microsoft Kinect sensor illustrates the effectiveness of the approach. DOI:10.1007/s10846-014-0146-2

[J-41] A. De Luca, R. Mattone, P. Robuffo Giordano, H. Ulbrich, M. Schwaiger, M. Van den Bergh, E. Koller-Meier, L. Van Gool, "

**Motion control of the CyberCarpet platform**,"

*IEEE Transactions on Control Systems Technology*, vol. 21, no. 2, pp. 410-427, 2013 [on-line since 6 Feb 2012] (pdf) [multimedia].

The CyberCarpet is an actuated platform that allows unconstrained locomotion of a walking user for Virtual Reality exploration. The platform consists of a linear treadmill covered by a ball-array carpet and mounted on a turntable, and is equipped with two actuating devices for linear and angular motion. The main control objective is to keep the walker close to the platform center in the most natural way, counteracting his/her voluntary motion while satisfying perceptual constraints. The motion control problem for this platform is not trivial since the system kinematics is subject to a nonholonomic constraint. In the first part of the paper we describe the kinematic control design devised within the CyberWalk project, where the linear and angular platform velocities are used as input commands and feedback is based only on walker’s position measurements obtained by an external visual tracking system. In particular, we present a globally stabilizing control scheme that combines a feedback and a feedforward action, based on a disturbance observer of the walker’s intentional velocity. We also discuss possible extensions to acceleration-level control and the related assessment of dynamic issues affecting a walker during his/her motion. The second part of the paper is devoted to the actual implementation of the overall system. As a proof of concept of a final full-scale platform, the mechanical design and realization of a small-scale prototype of the CyberCarpet is presented, as well as the visual localization method used to obtain the human walker’s position on the platform by an overhead camera. To validate the proposed motion control design, experimental results are reported and discussed for a series of motion tasks performed using a small tracked vehicle representative of a moving user. DOI:10.1109/TCST.2012.2185051

[J-40] F. Flacco, A. De Luca, I. Sardellitti, N. Tsagarakis, "

**On-line estimation of variable stiffness in flexible robot joints**,"

*The International Journal of Robotics Research*(Special Issue on Autonomous Physical Human-Robot Interaction), vol. 31, no. 13, pp. 1556-1577, 2012 [on-line since 29 Oct 2012] (pdf).

Variable Stiffness Actuators (VSAs) are currently explored as a new actuation approach to increase safety in pHRI and improve dynamic performance of robots. For control purposes, an accurate knowledge is needed of the varying stiffness at the robot joints, which is not directly measurable, nonlinearly depending on transmission deformation, and uncertain to be modeled. We address the on-line estimation of transmission stiffness in robots driven by VSA in antagonistic or serial configuration, without the need of joint torque sensing. The two-stage approach combines i) a residual-based estimator of the torque at the flexible transmission, and ii) a Recursive Least Squares stiffness estimator based on a parametric model. Further design refinements guarantee a robust behavior in the lack of velocity measures and in poor excitation conditions. The proposed stiffness estimation can be easily extended to multi-dof robots in a decentralized way, using only local motor and link position measurements. The method is tested through extensive simulations on the VSA-II device of the University of Pisa and on the Actuator with Adjustable Stiffness (AwAS) of IIT. Experiments on the AwAS platform validate the approach. DOI:10.1177/0278364912461813

[J-39] G. Milighetti, A. De Luca, "

**Prädiktive Blickregelung für einen redundanten humanoiden Roboterkopf**," ("Predictive gaze control of a redundant humanoid robot head,")

*at - Automatisierungstechnik*, vol. 60, no. 5, pp. 279-288, 2012 (pdf, in German).

Ein allgemeines Konzept für die Blickregelung eines redundanten Roboterkopfes wird präsentiert. Es basiert auf einem adaptiven Kalman-Filter, das den Zustand eines bewegten Zieles aufgrund der Positionsdaten schätzt, die von der im Kopf integrierten Stereokamera geliefert werden. Der Regler kombiniert eine Feedback- und eine Feedforward-Komponente, beide mit adaptiven Parametern, um eine optimale dynamische Antwort für beliebige unbekannte Zieltrajektorien zu gewährleisten. Für die Lösung der vorhandenen kinematischen Redundanz wird eine gewichtete Pseudoinverse eingesetzt. Die für die Berechnung der Gewichtungen realisierten Optimierungskriterien werden so ausgewählt, dass menschen ähnliche Bewegungen des Kopfes erreicht werden können. Experimentelle Ergebnisse mittels des Kopfes des humanoiden Roboters ARMAR-III werden präsentiert.

(English Abstract) A general concept for the gaze control of a redundant humanoid robot head is presented. It is based on an adaptive Kalman filter that predicts the next state of the moving target, processing the position information provided by a head-mounted stereo camera. The trajectory tracking control at the task level combines a proportional feedback and a feedforward term. The gains of both control actions are adapted in order to provide optimal dynamic response for unknown arbitrary target trajectories. To exploit kinematic redundancy, a weighted pseudoinverse is realized that takes into account different optimization criteria, so that human-like joint motions are achieved. Experimental results on the head of the humanoid robot ARMAR-III are presented. DOI:10.1524/auto.2012.0994 (Note: this is the German journal version of [C-117])

[J-38] J. Souman, P. Robuffo Giordano, M. Schwaiger, I. Frissen, T. Thümmel, H. Ulbrich, A. De Luca, H. Bülthoff, M. Ernst, "

**CyberWalk: Enabling unconstrained omnidirectional walking through virtual environments**,"

*ACM Transactions on Applied Perception*, vol. 8, no. 4, pp. 24:1-24:22, 2011 (pdf), with on-line Appendix.

Despite many recent developments in Virtual Reality, an effective locomotion interface which allows for normal walking through large virtual environments was still lacking until recently. Here, we describe the new CyberWalk omnidirectional treadmill system, which makes it possible for users to walk endlessly in any direction, while never leaving the confines of the limited walking surface. The treadmill system improves on previous designs, both in its mechanical features and in the control system employed to keep users close to the centre of the treadmill. As a result, users are able to start walking, vary their walking speed and direction, and stop walking like they would on a normal, stationary surface. The treadmill system was validated in two experiments, in which both the walking behaviour and the performance in a basic spatial updating task were compared to that during normal overground walking. The results suggest that walking on the CyberWalk treadmill is very close to normal walking, especially after some initial familiarization. Moreover, we did not find a detrimental effect of treadmill walking in the spatial updating task. The CyberWalk system constitutes a significant step forward to bringing the real world into the laboratory or workplace. DOI:10.1145/2043603.2043607

[J-37] J. Souman, P. Robuffo Giordano, I. Frissen, A. De Luca, M. Ernst, "

**Making virtual walking real: Perceptual evaluation of a new treadmill control algorithm**,"

*ACM Transactions on Applied Perception*, vol. 7, no. 2, pp. 11:1-11:14, 2010 (pdf).

For us humans, our most natural way of moving through the world is walking. One of the major challenges in present research on navigation in virtual reality is to enable users to physically walk through virtual environments. Although treadmills in principle allow users to walk for extended periods of time through large virtual environments, existing setups largely fail to produce a truly immersive sense of navigation. Partially, this is because of inadequate control of treadmill speed as a function of walking behaviour. Here, we present a new control algorithm that allows users to walk naturally on a treadmill, including starting to walk from standstill, stopping, and varying walking speed. The treadmill speed control consists of a feedback loop based on the measured user position relative to a given reference position, plus a feed-forward term based on on-line estimation of the user’s walking velocity. The purpose of this design is to make the treadmill compensate fully for any persistent walker motion, while keeping the accelerations exerted on the user as low as possible. We evaluated the performance of the algorithm by conducting a behavioural experiment in which we varied its most important parameters. Participants walked at normal walking speed and then, on an auditory cue, abruptly stopped. After being brought back to the centre of the treadmill by the control algorithm, they rated how smoothly the treadmill had changed its velocity in response to the change in walking speed. Ratings in general were quite high, indicating good control performance. Moreover, ratings clearly depended on the control algorithm parameters that were varied. Ratings were especially affected by the way the treadmill reversed its direction of motion. In conclusion, controlling treadmill speed in such a way that changes in treadmill speed are unobtrusive and do not disturb VR immersiveness is feasible on a normal treadmill with a straightforward control algorithm. DOI:10.1145/1670671.1670675

[J-36] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**Feature depth observation for image-based visual servoing: Theory and experiments**,"

*The International Journal of Robotics Research*, vol. 27, no. 10, pp. 1093-1116, 2008 (pdf) [multimedia].

In the classical image-based visual servoing framework, error signals are directly computed from image feature parameters, allowing in principle to obtain control schemes that need neither a complete 3D model of the scene, nor a perfect camera calibration. However, when the computation of control signals involves the interaction matrix, the current value of some 3D parameters is required for each considered feature, and typically a rough approximation of this value is used. With reference to the case of a point feature, for which the relevant 3D parameter is the depth Z, we propose a visual servoing approach where Z is observed and made available for servoing. This is achieved by interpreting depth as an unmeasurable state with known dynamics, and by building a nonlinear observer that asymptotically recovers the actual value of Z for the selected feature. A byproduct of our analysis is the rigorous characterization of camera motions that actually allow such observation. Moreover, in the case of a partially uncalibrated camera, it is possible to exploit complementary camera motions in order to preliminarily estimate the focal length without knowing Z. Simulation and experimental results are presented for a mobile robot with an on-board camera in order to illustrate the benefits of integrating the depth observation within classical visual servoing schemes. DOI:10.1177/0278364908096706

[J-35] A. De Santis, B. Siciliano, A. De Luca, A. Bicchi, "

**An atlas of physical human-robot interaction**,"

*Mechanism and Machine Theory*, vol. 43, no. 3, pp. 253–270, 2008 (pdf), 2017 Mechanisms and Machine Theory Award for Excellence (one of the top 10 most cited papers since the journal's first publication, based on Scopus; as such, it is now [free access]).

A broad spectrum of issues have to be addressed in order to tackle the problem of a safe and dependable physical Human–Robot Interaction (pHRI). In the immediate future, metrics related to safety and dependability have to be found in order to successfully introduce robots in everyday enviornments. While there are certainly also "cognitive" issues involved, due to the human perception of the robot (and vice versa), and other objective metrics related to fault detection and isolation, our discussion focuses on the peculiar aspects of "physical" interaction with robots. In particular, safety and dependability are the underlying evaluation criteria for mechanical design, actuation, and control architectures. Mechanical and control issues are discussed with emphasis on techniques that provide safety in an intrinsic way or by means of control components. Attention is devoted to dependability, mainly related to sensors, control architectures, and fault handling and tolerance. Suggestions are provided to draft metrics for evaluating safety and dependability in pHRI, and references to the works of the scientific groups involved in the pHRI research complete the study. The present atlas is a result of the EURON perspective research project ‘‘Physical Human-Robot Interaction in anthropic DOMains (PHRIDOM)’’, aimed at charting the new territory of pHRI, and constitutes the scientific basis for the ongoing STReP project ‘‘Physical Human–Robot Interaction: depENDability and Safety (PHRIENDS)’’, aimed at developing key components for the next generation of robots, designed to share their environment with people. DOI:10.1016/j.mechmachtheory.2007.03.003

[J-34] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**Image-based visual servoing schemes for nonholonomic mobile manipulators**,"

*Robotica*, vol. 25, no. 2, pp. 129-145, 2007 (pdf).

We consider the task-oriented modeling of the differential kinematics of nonholonomic mobile manipulators (NMMs). A suitable NMM Jacobian is defined that relates the available input commands to the time derivative of the task variables, and can be used to formulate and solve kinematic control problems. When the NMM is redundant with respect to the given task, we provide an extension of two well-known redundancy resolution methods for fixed-base manipulators (Projected Gradient and Task Priority) and introduce a novel technique (Task Sequencing) aimed at improving performance, e.g., avoiding singularities. The proposed methods are applied then to the specific case of image-based visual servoing, where the NMM image Jacobian combines the interaction matrix and the kinematic model of the mobile manipulator. Comparative numerical results are presented for two case studies. DOI:10.1017/S0263574706003262

[J-33] R. Mattone, A. De Luca, "

**Nonlinear fault detection and isolation in a three-tank heating system**,"

*IEEE Transactions on Control Systems Technology*, vol. 14, no. 6, pp. 1158-1166, 2006 (pdf).

We consider the fault detection and isolation (FDI) problem for a nonlinear dynamic plant (the IFATIS Heating System Benchmark) affected by actuator and/or sensor faults. A general procedure is proposed for modeling faults of sensors that measure the state of a nonlinear system, so that each sensor fault is typically associated to a set of (always concurrent) fault inputs and the resulting dynamic equations are affine in the introduced fault inputs. This allows the application of recently developed nonlinear FDI techniques, slightly extended to cover the considered model structure. For the presented case study, assuming nonconcurrency of the faults in the hardware components, we describe in detail the modeling procedure, the synthesis of residual generators, and the design of a combinatorial logics that recovers perfect isolation. Simulation results are reported in the presence of input and measurement noise. DOI:10.1109/TCST.2006.880221

[J-32] R. Mattone, A. De Luca, "

**Relaxed fault detection and isolation: An application to a nonlinear case study**,"

*Automatica*, vol. 42, no. 1, pp. 109-116, 2006 (pdf).

Given a number of possibly concurrent faults (and disturbances) that may affect a nonlinear dynamic system, it may not be possible to solve the standard fault detection and isolation (FDI) problem, i.e., to detect and isolate each single fault from all other, possibly concurrent faults and disturbances, due to the violation of the available necessary conditions of geometric nature. Motivated by a robotic application where this negative situation structurally occurs, we propose some relaxed formulations of the FDI problem and show how necessary and sufficient conditions for their solution can be derived from those available for standard FDI. The design of a hybrid residual generator follows directly from the fulfillment of the corresponding solvability conditions. In the considered nonlinear case study, a robotic system affected by possible actuator and/or force sensor faults, we detail the application of these results and present experimental tests for validation. DOI:10.1016/j.automatica.2005.08.018

[J-31] A. De Luca, B. Siciliano, L. Zollo, "

**PD control with on-line gravity compensation for robots with elastic joints: Theory and experiments**,"

*Automatica*, vol. 41, no. 10, pp. 1809-1819, 2005 (pdf).

A proportional-derivative (PD) control with on-line gravity compensation is proposed for regulation tasks of robot manipulators with elastic joints. The work extends a previous PD control with constant gravity compensation at the desired configuration. The control law requires measuring only position and velocity on the motor side of the elastic joints, while the on-line gravity compensation torque uses a biased measure of the motor position. It is proved via a Lyapunov argument that the control law globally asymptotically stabilizes the desired robot configuration. A simulation study on a two-joint arm reveals the better performance that can be obtained with the new scheme as compared to the case of constant gravity compensation. Moreover, the proposed controller is experimentally tested on an eight-joint cable-driven robot manipulator, in combination with a point-to-point interpolating trajectory, showing the practical advantages of the on-line compensation. DOI:10.1016/j.automatica.2005.05.009

[J-30] L. Zollo, B. Siciliano, A. De Luca, E. Guglielmelli, P. Dario, "

**Compliance control for an anthropomorphic robot with elastic joints: Theory and experiments**,"

*ASME Transactions: Journal of Dynamic Systems, Measurements, and Control*, vol. 127, no. 3, pp. 321-328, 2005 (pdf).

Studies on motion control of robot manipulators with elastic joints are basically aimed at improving robot performance in tracking or regulation tasks. In the interaction between robots and environment, instead, the main objective of a control strategy should be the reduction of the vibrational and chattering phenomena that elasticity in the robot joints can cause. This work takes into account working environments where unexpected interactions are experienced and proposes a compliance control scheme in the Cartesian space to reduce the counter effects of elasticity. Two theoretical formulations of the control law are presented, which differ for the term of gravity compensation. For both of them the closed-loop equilibrium conditions are evaluated and asymptotic stability is proven through the direct Lyapunov method. The two control laws are applied to a particular class of elastic robot manipulators, i.e., cable-actuated robots, since their intrinsic mechanical compliance can be successfully utilized in applications of biomedical robotics and assistive robotics. A compared experimental analysis of the two formulations of compliance control is finally carried out in order to verify stability of the two closed-loop systems as well as the capability to control the robot force in the interaction. DOI:10.1115/1.1978911

[J-29] M. Benosman, G. Le Vey, L. Lanari, A. De Luca, "

**Rest to rest motion for planar multi-link flexible manipulators through backward recursion**,"

*ASME Transactions: Journal of Dynamic Systems, Measurements, and Control*, vol. 126, no. 1, pp. 115-123, 2004 (pdf).

In this work is considered the problem of rest-to-rest motion in a desired pre-fixed time for planar flexible manipulators. We introduce a simple idea permitting the minimization of end-effector residual vibration when reaching a desired angular equilibrium position, in a pre-fixed desired travelling time. The results hold without considering internal elastic damping effect, using a classical controller with feedforward plus joint feedback terms. The new approach concerns the computation of the feedforward control, which is based on backward integration of the elastic dynamics, starting from a rest position of the flexible arms. This backward integration yields basically elastic trajectories permitting to reach the final desired end-effector position without oscillation. The feedback controller is then used to stabilize locally the actual states along these desired trajectories. However, for fast rest to rest motion, the feedback compensator fails to drive the system states along the desired trajectories, this being due to the relatively large initial elastic error. To overcome this limitation, proper joint motion is planned between the desired initial and final positions through optimization techniques, the goal being the minimization of the initial elastic error associated to these joint trajectories. The optimal planning technique is formulated as a Pontryagin optimal control problem. This scheme is validated via numerical tests as well as experiments on a flexible two-link planar manipulator. DOI:10.1115/1.1649976

[J-28] S. Iannitti, A. De Luca, "

**Dynamic feedback control of XYnR planar robots with n rotational passive joints**,"

*Journal of Robotic Systems*, vol. 20, no. 5, pp. 251-270, 2003 (pdf).

We consider the problem of trajectory planning and control for an XYnR planar robot with the first two joints (rotational or prismatic) actuated and n rotational passive joints, moving both in the presence and the absence of gravity. Under the assumption that each passive link is attached at the center of percussion of the previous passive link, dynamics of the system can be expressed through the behavior of n special points of the plane. These points are called link-related acceleration points (LRAP) since their instantaneous acceleration is oriented as the axis of the related passive links. Moreover, LRAP dynamics present a backward recursive form which can be exploited to recursively design a dynamic feedback that completely linearizes the system equations. We use this approach to solve trajectory planning and tracking problems and report simulation results obtained for an RR2R robot having the first two rotational joints actuated. DOI:10.1002/rob.10085

[J-27] A. De Luca, S. Iannitti, R. Mattone, G. Oriolo, "

**Underactuated manipulators: Control properties and techniques**,"

*Machine Intelligence and Robotic Control*, vol. 4, no. 3, pp. 113-125, 2002 (pdf of final submission).

We consider planning and control problems for underactuated manipulators, a special instance of mechanical systems having fewer input commands than degrees of freedom. This class includes robots with passive joints, elastic joints, or flexible links. Structural control properties are investigated, showing that manipulators with passive joints in the absence of gravity are the most difficult to control. With reference to these, solutions are proposed for the typical problems of trajectory planning, trajectory tracking, and set-point stabilization. The relevance of nonlinear control techniques such as dynamic feedback linearization and iterative steering is clarified through illustrative examples. [No DOI]

[J-26] G. Oriolo, A. De Luca, M. Vendittelli, "

**WMR control via dynamic feedback linearization: Design, implementation and experimental validation**,"

*IEEE Transactions on Control Systems Technology*, vol. 10, no. 6, pp. 835-852, 2002 (pdf).

The subject of this paper is the motion control problem of wheeled mobile robots (WMRs) in environments without obstacles. With reference to the popular unicycle kinematics, it is shown that dynamic feedback linearization is an efficient design tool leading to a solution simultaneously valid for both trajectory tracking and set-point regulation problems. The implementation of this approach on the laboratory prototype SuperMARIO, a two-wheel differentially-driven mobile robot, is described in detail. To assess the quality of the proposed controller, we compare its performance with that of several existing control techniques in a number of experiments. The obtained results provide useful guidelines for WMR control designers. DOI:10.1109/TCST.2002.804116

[J-25] A. De Luca, G. Oriolo, "

**Trajectory planning and control for planar robots with passive last joint**,"

*The International Journal of Robotics Research*, vol. 21, no. 5-6, pp. 575-590, 2002 (pdf).

We present a method for trajectory planning and control of planar robots with a passive rotational last joint. These underactuated mechanical systems, which are subject to nonholonomic second-order constraints, are shown to be fully linearized and input-output decoupled by means of a nonlinear dynamic feedback. This objective is achieved in a unified framework, both in the presence or absence of gravity. The linearizing output is the position of the center of percussion of the last link. Based on this result, one can plan smooth trajectories joining in finite time any initial and desired final state of the robot; in particular, transfers between inverted equilibria and swing-up maneuvers under gravity are easily obtained. We also address the problem of avoiding the singularity induced by the dynamic linearization procedure through a careful choice of output trajectories. A byproduct of the proposed method is the straightforward design of exponentially stable tracking controllers for the generated trajectories. Simulation results are reported for a 3R robot moving in a horizontal and vertical plane. Possible extensions of the approach and its relationships with the differential flatness technique are briefly discussed. DOI:10.1177/027836402321261940

[J-24] A. De Luca, G. Oriolo, "

**Comments on 'Adaptive Variable Structure Set-Point Control of Underactuated Robots'**,"

*IEEE Transactions on Automatic Control*, vol. 46, no. 5, pp. 809-811, 2001 (pdf).

In this note, we point out the fallacies of a recent paper concerning the stabilization of underactuated robots. DOI:10.1109/9.920807

[J-23] A. De Luca, R. Mattone, G. Oriolo, "

**Stabilization of an underactuated planar 2R manipulator**,"

*International Journal of Robust and Nonlinear Control*, vol. 10, no. 4, pp. 181-198, 2000 (pdf).>

We describe a technique for the stabilization of a 2R robot moving in the horizontal plane with a single actuator at the base, an interesting example of underactuated mechanical system that is not smoothly stabilizable. The proposed method is based on a recently introduced iterative steering paradigm, which prescribes the repeated application of an error contracting open-loop control law. In order to compute efficiently such a law, the dynamic equations of the robot are transformed via partial feedback linearization and nilpotent approximation. Simulation and experimental results are presented for a laboratory prototype. DOI:10.1002/(SICI)1099-1239(20000415)10:4<181::AID-RNC471>3.0.CO;2-X

[J-22] A. De Luca, "

**Decoupling and feedback linearization of robots with mixed rigid/elastic joints**,"

*International Journal of Robust and Nonlinear Control*(Special Issue on Twenty Years of Feedback Linearization of Nonlinear Systems), vol. 8, no. 11, pp. 965-977, 1998 (pdf).

We consider some theoretical aspects of the control problem for rigid link robots having some joints rigid and some with non-negligible elasticity. We start from the reduced model of robots with all joints elastic introduced by Spong, which is linearizable by static feedback. For the mixed rigid/elastic joint case, we give structural necessary and sufficient conditions for input-output decoupling and full-state linearization via static state feedback. These turn out to be very restrictive. However, when a robot fails to satisfy these conditions, we show that a physically motivated dynamic state feedback will always guarantee the same result. The analysis is performed without resorting to the state-space equation format. As a result, the explicit form of the exact linearizing and input-output decoupling controllers is provided directly in terms of the robot dynamic model terms. DOI:10.1002/(SICI)1099-1239(199809)8:11<965::AID-RNC371>3.0.CO;2-4

[J-21] A. De Luca, R. Mattone, G. Oriolo, "

**Steering a class of redundant mechanisms through end-effector generalized forces**,"

*IEEE Transactions on Robotics and Automation*, vol. 14, no. 2, pp. 329-335, 1998 (pdf).

A particular class of underactuated systems is obtained by considering kinematically redundant manipulators for which all joints are passive and the only available inputs are forces/torques acting on the end-effector. Under the assumption that the degree of redundancy is provided by prismatic joints located at the base, we address the problem of steering the robot between two arbitrary equilibrium configurations. By performing a preliminary partial feedback linearization, the dynamic equations take a convenient triangular form, which is further simplified under additional hypotheses. We give sufficient conditions for controllability of this kind of mechanisms. With a PPR robot as a case study, an algorithm is proposed for computing end-effector commands that produce the desired reconfiguration in finite time. Simulation results and a discussion on possible generalizations are given. DOI:10.1109/70.681252

[J-20] A. De Luca, G. Oriolo, "

**Nonholonomic behavior in redundant robots under kinematic control**,"

*IEEE Transactions on Robotics and Automation*, vol. 13, no. 5, pp. 776-782, 1997 (pdf).

We analyze the behavior of redundant robots when the joint motion is generated by inverting task velocity commands through a kinematic control scheme. Depending on the chosen inversion scheme, the robot motion is subject to differential constraints that may or may not be integrable. Accordingly, we give a classification in terms of holonomic, partially nonholonomic, and completely nonholonomic behavior, pointing out also the relationship with the so-called cyclicity property. This general classification is illustrated by means of several examples. When the kinematic control scheme is nonholonomic, the whole configuration space of the robot is accessible by a proper choice of the task input commands. Under this assumption, we address the joint reconfiguration problem, namely the design of end-effector velocity commands that drive the robot to a desired joint configuration. To solve this problem, it is possible to borrow existing methods for motion planning of nonholonomic mechanical systems, such as the sinusoidal steering technique for chained form systems. DOI:10.1109/70.631239

[J-19] A. De Luca, R. Mattone, G. Oriolo, "

**Control of redundant robots under end-effector commands: A case study in underactuated systems**,"

*Applied Mathematics and Computer Science*, vol. 7, no. 2, pp. 225-251, 1997 (pdf of final submission).

We analyze the control problem for a kinematically redundant robot driven by forces/torques imposed on the end-effector, an interesting example of underactuated system. A convenient format for the dynamic equations of this mechanism can be obtained via partial feedback linearization. In particular, we point out the existence of two special forms in which the system can be put under suitable assumptions, namely the second-order triangular and Caplygin forms. Nonlinear controllability tools are utilized to derive conditions under which it is possible to steer the robot between two given configurations using end-effector commands. With a PPR robot as a case study, a steering algorithm is proposed that achieves reconfiguration in finite time. Simulation results and a discussion on possible generalizations are presented. [No DOI]

[J-18] A. De Luca, G. Oriolo, "

**Reconfiguration of redundant robots under kinematic inversion**,"

*Advanced Robotics*, vol. 10, n. 3, pp. 249-263, 1996 (pdf).

We consider the problem of reconfiguring the joints of a redundant robot driven only through end-effector velocity commands. Depending on the chosen kinematic inversion scheme, this system behavior is subject to differential constraints that may be integrable or not. An analogy is established with non-holonomic systems, allowing the use of existing techniques to design cartesian inputs that bring the robot to the desired configuration. Two different control approaches are presented for a robot with a single degree of redundancy, based on the holonomy angle concept and on sinusoidal steering of chained-form systems. Simulation results are reported and generalizations are briefly discussed. DOI:10.1163/156855395X00382

[J-17] A. De Luca, S. Panzieri, "

**End-effector regulation of robots with elastic elements by an iterative scheme**,"

*International Journal of Adaptive Control and Signal Processing*, vol. 10, no. 4/5, pp. 379-393, 1996 (pdf).

The regulation of motor variable positions in robots with elastic elements has been solved using PD linear controllers in the absence of gravity and with the addition of a-model-based feedforward term when gravity is present. When the mass of the links is not known, an iterative learning scheme can be derived to obtain the same result for both joint elasticity and link flexibility. An extension to end-effector regulation with a similar two-stage and hence time-consuming scheme has been proposed. In this paper we show the feasibility of a new iterative one-stage scheme able to directly regulate the end-effector position in robots with joint elasticity and in robots whose distributed flexibility is limited for each link to the plane orthogonal to the associated motor axis. Experimental results are included to show the improved rate of convergence of the proposed scheme applied to a two-link flexible robot available in our laboratory. DOI:10.1002/(SICI)1099-1115(199607)10:4/5<379::AID-ACS369>3.0.CO;2-O

[J-16] A. De Luca, C. Manes, "

**Modeling robots in contact with a dynamic environment**,"

*IEEE Transactions on Robotics and Automation*, vol. 10, no. 4, pp. 542-548, 1994 (pdf).

A control-oriented modeling approach for describing kinematics and dynamics of robots in contact with a dynamic environment is presented. In many robotic tasks the manipulator in contact cannot be simply modeled as a kinematically constrained system. Conversely, modeling of robot-environment interactions through dynamic impedance may not fit the task layout. A suitable model structure is proposed in this note that handles the more general case in which purely kinematic constraints on the robot end-effector live together with dynamic interactions. Feasible end-effector configurations are parameterized from the environment point of view, using a minimal set of coordinates. Accordingly, a description is obtained also for admissible velocities and contact forces. In particular, a force parameterization is chosen so as to separate static reaction forces from active forces responsible for energy transfer between robot and environment. The overall dynamics of the coupled robot-environment system is obtained in a single framework. The introduced modeling technique naturally leads to the design of new hybrid control laws. DOI:10.1109/70.313104

[J-15] A. De Luca, S. Panzieri, "

**An iterative scheme for learning gravity compensation in flexible robot arms**,"

*Automatica*, vol. 30, no. 6, pp. 993-1002, 1994 (pdf).

Mimicking the case of rigid robot arms, the set-point regulation problem for manipulators with flexible links moving under gravity can be solved by either model-based compensation or PID control. The former cannotb e applied if an unknown payload is presentor when model parameters are poorly estimated, while the latter requires fine and lengthy tuning of gains in order to achieve good performance on the whole workspace. Moreover, no global convergence proof has been yet given for PID control of flexible robot arms. In this paper, a simple iterative scheme is proposed for generating exact gravity compensation at the desired set point, without the knowledge of rigid or flexible dynamic model terms. The control law starts with a PD action on the error at the joint level, updating at discrete instants an additional feedforward term. Global convergence of the scheme is proved under a mild condition on the proportional gain and a structural property on the arm stiffness, which is usually satisfied in practice. The proposed learning scheme is also extended to the direct control of the end-effector (tip) position. Experimental results are presented for a two-link robot with a flexible forearm moving on a tilted plane. DOI:10.1016/0005-1098(94)90192-9

[J-14] A. De Luca, M.D. Di Benedetto, "

**Control of nonholonomic systems via dynamic compensation**,"

*Kybernetika*, vol. 29, no. 6, pp. 593-608, 1993 (pdf).

The problem of controlling nonholonomic systems via dynamic state feedback and its structural aspects are analyzed. Advantages and drawbacks with respect to the use of static state feedback laws are discussed. In particular, nonholonomic constraints are shown to yield possible singularities in the dynamic extension process. Nevertheless, these singularities can be avoided by the proper design of a discontinuous external control law achieving stabilization of the transformed linear system. This is illustrated through simulations for a car-like vehicle. [No DOI]

[J-13] A. De Luca, S. Panzieri, "

**Learning gravity compensation in robots: Rigid arms, elastic joints, flexible links**,"

*International Journal of Adaptive Control and Signal Processing*, vol. 7, no. 5, pp. 417-433, 1993 (pdf).

The setpoint regulation problem for robotic manipulators is a basic task that can be solved either by PID control or by model-based gravity compensation. These approaches are commonly applied both to rigid arms and to robots with flexible links and/or elastic joints. However, PID control requires fine and lengthy tuning of gains in order to achieve good performance over the whole workspace. Moreover, no global convergence proof has yet been given for this control law in the case of flexible links or elastic joints. On the other hand, a constant or even a configuration-dependent gravity compensation is only an approximate solution when an unknown payload is present or when model parameters are poorly estimated. In this paper a simple iterative scheme is proposed for generating exact gravity compensation at the desired setpoint without the knowledge of dynamic model terms. The resulting control law is shown to be global asymptotically stable for rigid arms as well as for manipulators with elastic joints or flexible links. Starting with a PD action on the error at the joint (i.e. motor) level, an additional feedforward term is built and updated at discrete instants. Convergence of the scheme is proved under a mild condition on the proportional gain, related to a bound on the gravity terms. In the presence of concentrated or distributed flexibility a structural property of the joint or of the link stiffness is further required, largely satisfied in practice. Simulation results are given for a three-link rigid arm and experimental results are also presented for a two-link robot with a flexible forearm. DOI:10.1002/acs.4480070510

[J-12] A. De Luca, B. Siciliano, "

**Regulation of flexible arms under gravity**,"

*IEEE Transactions on Robotics and Automation*, vol. 9, no. 4, pp. 463-467, 1993 (pdf).

A simple controller is presented for the regulation problem of robot arms with flexible links under gravity. It consists of a joint PD feedback plus a constant feedforward. Global asymptotic stability of the reference equilibrium state is shown under a structural assumption about link elasticity and a mild condition on the proportional gain. The result holds also in the absence of internal damping of the flexible arm. A numerical case study is presented. DOI:10.1109/70.246057

[J-11] A. De Luca, B. Siciliano, "

**Inversion-based nonlinear control of robot arms with flexible links**,"

*AIAA Journal of Guidance, Control, and Dynamics*, vol. 16, no. 6, pp. 1169-1176, 1993 (pdf).

The design of inversion-based nonlinear control laws solving the problem of accurate trajectory tracking for robot arms having flexible links is considered. It is shown that smooth joint trajectories can always be exactly reproduced preserving internal stability of the closed-loop system. The interaction between the Lagrangian/assumed modes modeling approach and the complexity of the resulting inversion control laws is stressed. The adoption of clamped boundary conditions at the actuation side of the flexible links allows considerable simplification with respect to the case of pinned boundary conditions. The resulting control is composed of a nonlinear state feedback compensation term and of a linear feedback stabilization term. A feedforward strategy for the nonlinear part is also investigated. Simulation results are presented for a planar manipulator with two flexible links, displaying the performance of the proposed controllers also in terms of end-effector behavior. DOI:10.2514/3.21142

[J-10] A. De Luca, G. Oriolo, B. Siciliano, "

**Robot redundancy resolution at the acceleration level**,"

*Laboratory Robotics and Automation*, vol. 4, no. 2, pp. 97-106, 1992 (pdf).

We present different methods for solving robot kinematic redundancy at the acceleration level. Their features are discussed with respect to velocity solution schemes and potential benefits are highlighted. The following strategies are pursued: local optimization of objective functions that depend on both position and velocity, task augmentation with stable internal motion, and a second-order extended Jacobian approach. The resulting solutions are critically compared in the light of achieving enhanced task trajectory tracking performance with reduced computational complexity. The numerical results obtained for a case study with a planar arm validate the theoretical findings. [No DOI]

[J-9] A. De Luca, G. Paesano, G.Ulivi, "

**A frequency-domain approach to learning control: Implementation for a robot manipulator**,"

*IEEE Transactions on Industrial Electronics*, vol. 39, no. 1, pp. 1-10, 1992 (pdf).

A frequency-domain approach to the analysis and design of learning control laws for achieving a desired repetitive behavior in a dynamical system is presented. The scheme uses two separate filters in order to obtain rapid improvement in a specified bandwidth, while cutting off possibly destabilizing dynamic effects that would bar learning convergence. In this way the trade-off between global convergence conditions and approximate learning of trajectories is made explicit. The synthesis is presented for single-input, single-output (SISO) linear systems, but the method is of general application. The proposed learning controller has been used for exact tracking of repetitive trajectories in robot manipulators. In particular, actuator inputs that enable accurate reproduction of robot joint-space trajectories are learned in a few iterations without the knowledge of the robot dynamic model. Implementation aspects are discussed, and experimental results are reported. DOI:10.1109/41.121905

[J-8] A. De Luca, B. Siciliano, "

**Closed-form dynamic model of planar multi-link lightweight robots**,"

*IEEE Transactions on Systems, Man, and Cybernetics*, vol. 21, no. 4, pp. 826-839, 1991 (pdf).

Closed-form equations of motion are presented for planar lightweight robot arms with multiple flexible links. The kinematic model is based on standard frame transformation matrices describing both rigid rotation and flexible displacement, under small deflection assumption. The Lagrangian approach is used to derive the dynamic model of the structure. Links are modeled as Euler-Bernoulli beams with proper clamped-mass boundary conditions. The assumed modes method is adopted in order to obtain a finite-dimensional model. Explicit equations of motion are detailed for two-link case assuming two modes of vibration for each link. The associated eigenvalue problem is discussed in relation with the problem of time-varying mass boundary conditions for the first link. The model is cast in a compact form that is linear with respect to a suitable set of constant parameters. Extensive simulation results that validate the theoretical derivation are included. DOI:10.1109/21.108300

[J-7] A. De Luca, G. Oriolo, "

**The reduced gradient method for solving redundancy in robot arms**,"

*Robotersysteme*, vol. 7, no. 2, pp. 117-122, 1991 (pdf).

An efficient computational scheme for solving inverse kinematicc problems in redundant robot arms is presented. When following a given end-effector trajectory, successive internal arm configurations are in general selected by local optimization of a given performance criterion. Typically, joint displacements are derived using the Projected Gradient method, involving pseudoinversion fo the robot Jacobian and projection in its null-space. However, this technique is computationally intensive. In this paper, an alternative approach is proposed based on the Reduced Gradient method, which allows to deal explicitly only with the reundant degrees of freedom. The superiority of this technique for solving redundancy is illustrated analytically in a simple case, and numerically by simulation of a four-link planar arm. Optimization of various criteria like manipulability, available joint range, and distance form obstacles is considered. Extensions of the method are also briefly discussed. [No DOI]

[J-6] A. De Luca, L. Lanari, G. Oriolo, "

**A sensitivity approach to optimal spline robot trajectories**,"

*Automatica*, vol. 27, no. 3, pp. 535-539, 1991 (pdf).

A robot trajectory planning problem is considered. Using smooth interpolating cubic splines as joint space trajectories, the path is parameterized in terms of time intervals between knots. A minimum time optimization problem is formulated under maximum torque and velocity constraints, and is solved by means of a first order derivative-type algorithm for semi-infinite nonlinear programming. Feasible directions in the parameter space are generated using sensitivity coefficients of the active constraints. Numerical simulations are reported for a two-link Scara robot. The proposed approach can be used for optimizing more general objective functions under different types of constraints. DOI:10.1016/0005-1098(91)90111-E

[J-5] A. De Luca, G. Ulivi, "

**Design of an exact nonlinear controller for induction motors**,"

*IEEE Transactions on Automatic Control*, vol. 34, no. 12, pp. 1304-1307, 1989 (pdf).

A novel approach to the control of induction motors is presented. The approach is based on differential-geometric concepts for the control of nonlinear systems. Structural properties of the model are pointed out, and a proper selection of physically meaningful system outputs is indicated which yields, by means of static state-feedback, exact state linearization and input-output decoupling of the closed-loop system. The approach is used to design a controller for motor torque and flux. Simulation results are included. DOI:10.1109/9.40783

[J-4] A. De Luca, B. Siciliano, "

**Trajectory control of a non-linear one-link flexible arm**,"

*International Journal of Control*, vol. 50, no. 5, pp. 1699-1715, 1989 (pdf).

The trajectory-tracking control problem is considered for a one-link flexible arm described by a non-linear model. Two meaningful system outputs are chosen; namely, the joint angle and the angular position of a suitable point along the link. The common goal is to stiffen the behaviour of the flexible link with respect to the chosen output. Based on the input-output inversion algorithm, a state-feedback control law is designed that enables exact tracking of any smooth trajectory specified for the output. In the closed loop an unobservable dynamics naturally arises, related to the variables describing the arm's distributed flexibility. Joint-based design is shown to be always stable, whereas in the link-point design the closed-loop dynamics may become unstable depending on the location of the output along the link. Open- versus closed-loop strategies are developed and compared. Extensive simulation results are included. DOI:10.1080/00207178908953460

[J-3] A. De Luca, P. Lucibello, G. Ulivi, "

**Inversion techniques for trajectory control of flexible robot arms**,"

*Journal of Robotic Systems*, vol. 6, no. 4, pp. 325-344, 1989 (pdf).

A general framework is given for computing the torques that are needed for moving a flexible arm exactly along a given trajectory. This torque computation requires a dynamic generator system, as opposed to the rigid case, and can be accomplished both in an open- or in a closed-loop fashion. In the open-loop case, the dynamic generator is the full or reduced order inverse system associated to the arm dynamics and outputs. In order to successfully invert the arm dynamics, the torque generator should be a stable system. The stability properties depend on the chosen system output, that is on the robot variables (e.g., joint or end-effector) to be controlled. The same inversion technique can be applied for closed-loop trajectory control of flexible robots. A simple but meaningful nonlinear dynamic model of a one-link flexible arm is used to illustrate different feasible control strategies. Simulation results are reported that display the effects of the system output choice on the closed-loop stability and on the overall tracking performance. DOI:10.1002/rob.4620060403

[J-2] P. Caravani, A. De Luca, "

**Aggregation in Sraffa's simple production model**,"

*Journal of Economics*, vol. 47, no. 2, pp. 167-193, 1987 (pdf).

*No abstract in this paper.* DOI:10.1007/BF01237550

[J-1] A. De Luca, G. Di Pillo, "

**Exact augmented Lagrangian approach to multilevel optimization of large-scale systems**,"

*International Journal of Systems Science*, vol. 18, no. 1, pp. 157-176, 1987 (pdf).

An approach based on the exact augmented lagrangian function is developed for the optimization of large-scale systems composed of interconnected units. The decomposition and coordination strategies are examined and various schemes of upper-level coordination are proposed, all of which are formulated as unconstrained quadratic minimization problems. Convergence analysis is performed exploiting an analogy with minimization by relaxation methods. Numerical examples are reported. DOI:10.1080/00207728708963956

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### Edited books

[E-1] B. Siciliano, A. De Luca, C. Melchiorri, G. Casalino (Eds.), "**Advances in Control of Articulated and Mobile Robots**,"

*Springer Tracts in Advanced Robotics*, vol. 10, Springer Verlag, Berlin, 2004 (front matter pdf). ISBN: 978-3-540-20783-2. DOI:10.1007/b10628

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### Book chapters

[BC-15] A. De Luca, W. Book, "**Robots with flexible elements**," in B. Siciliano, O. Khatib (Eds.)

*Springer Handbook of Robotics*(2nd Edition), Springer International Publishing, chapter 11, pp. 243-282, 2016 (pdf). ISBN: 978-3-319-32550-7. DOI:10.1007/978-3-319-32552-1

[BC-14] A. De Luca, "

**Robotica**," in

*Enciclopedia italiana di scienze, lettere ed arti*, Appendice IX, vol. 2, pp.444-446, Istituto della Enciclopedia Italiana, Roma, 2015 (in Italian, pdf). ISBN 978-88-12-00557-4.

[BC-13] A. De Luca, "

**Flexible robots**," in J. Baillieul, T. Samad (Eds.)

*Encyclopedia of Systems and Control*, Springer, London, pp. 451-458, 2015 (pdf - on-line version). ISBN: 978-1-4471-5057-2. DOI:10.1007/978-1-4471-5058-9_176 (on-line since 2 Apr 2014, DOI:10.1007/978-1-4471-5102-9_176-1)

[BC-12] A. De Luca, W. Book, "

**Robots with flexible elements**," in B. Siciliano, O. Khatib (Eds.)

*Springer Handbook of Robotics*, Springer Verlag, Berlin, chapter 13, pp. 287-319, 2008 (pdf). ISBN: 978-3-540-23957-4. DOI:10.1007/978-3-540-30301-5_14 (Note: More about the handbook here)

[BC-11] A. De Luca, G. Oriolo, M. Vendittelli, S. Iannitti, "

**Planning motions for robotic systems subject to differential constraints**," in B. Siciliano, A. De Luca, C. Melchiorri, G. Casalino (Eds.)

*Advances in Control of Articulated and Mobile Robots*, Springer Tracts in Advanced Robotics, vol. 10, pp. 1-38, Springer Verlag, Berlin, 2004 (pdf). ISBN: 978-3-540-20783-2. DOI:10.1007/978-3-540-44410-7_1

[BC-10] A. De Luca, V. Caiano, D. Del Vescovo, "

**Experiments on rest-to-rest motion of a flexible arm**," in B. Siciliano, P. Dario (Eds.)

*Experimental Robotics VIII*, Springer Tracts in Advanced Robotics, vol. 5, pp. 338-349, Springer Verlag, Berlin, 2003 (pdf). ISBN: 978-3-540-00305-2. DOI:10.1007/3-540-36268-1_30

[BC-9] A. De Luca, G. Oriolo, M. Vendittelli, "

**Control of wheeled mobile robots: An experimental overview**," in S. Nicosia, B. Siciliano, A. Bicchi, P. Valigi (Eds.)

*RAMSETE. Articulated and Mobile Robots for Services and Technology*, Lecture Notes in Control and Information Sciences, vol. 270, pp. 181-226, Springer Verlag, London, 2001 (pdf). ISBN: 978-3-540-42090-3. DOI:10.1007/3-540-45000-9_8

[BC-8] A. De Luca, "

**Trajectory control of flexible manipulators**," in B. Siciliano, K.P. Valavanis (Eds.)

*Control Problems in Robotics and Automation*, Lecture Notes in Control and Information Sciences, vol. 230, pp. 83-104, Springer Verlag, London, 1998 (pdf). ISBN: 978-3-540-76220-1. DOI:10.1007/BFb0015078

[BC-7] A. De Luca, G. Oriolo, C. Samson, "

**Feedback control of a nonholonomic car-like robot**," in J.-P. Laumond (Ed.)

*Robot Motion Planning and Control*, Lecture Notes in Control and Information Sciences, vol. 229, pp. 171-253, Springer Verlag, London, 1998 (pdf). ISBN: 978-3-540-42090-3. DOI:10.1007/BFb0036073 (Note: The whole book in PDF format can be downloaded from here)

[BC-6] A. De Luca, B. Siciliano, "

**Flexible links**," in C. Canudas de Wit, B. Siciliano, G. Bastin (Eds.)

*Theory of Robot Control*, pp. 219-261, Springer Verlag, Berlin, 1996 (pdf). ISBN: 3540760547.

[BC-5] A. De Luca, P. Tomei, "

**Elastic joints**," in C. Canudas de Wit, B. Siciliano, G. Bastin (Eds.)

*Theory of Robot Control*, pp. 179-217, Springer Verlag, Berlin, 1996 (pdf). ISBN: 3540760547.

[BC-4] A. De Luca, B. Siciliano, "

**Motion and force control**," in C. Canudas de Wit, B. Siciliano, G. Bastin (Eds.)

*Theory of Robot Control*, pp. 141-175, Springer Verlag, Berlin, 1996 (pdf). ISBN: 3540760547.

[BC-3] A. De Luca, G. Oriolo, "

**Modelling and control of nonholonomic mechanical systems**," in J. Angeles, A. Kecskemethy (Eds.)

*Kinematics and Dynamics of Multi-Body Systems*, CISM Courses and Lectures, vol. 360, pp. 277-342, Springer Verlag, Wien, 1995 (pdf). ISBN: 3211827315.

[BC-2] A. De Luca, S. Monaco, "

**Robotica**," in

*Enciclopedia Italiana Treccani*, Appendice V, vol. 4, pp. 553-557, Treccani, Roma, 1994 (in Italian, on line).

[BC-1] A. De Luca, "

**Redundant robots**," in M.W. Spong, F. Lewis, C.T. Abdallah (Eds.)

*Robot Control: Dynamics, Motion Planning, and Analysis*, IEEE Press, New York, pp. 435-439, 1993 (pdf). ISBN: 978-0780304048.

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### Stand-alone videos (in conference proceedings)

[V-1] F. Flacco, A. De Luca, "**Safe physical human-robot collaboration**," 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, J, p. 2072, 2013 (pdf) [video]. DOI:10.1109/IROS.2013.6696635, IROS 2013 Best Video Award Finalist

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### Conferences

[C-142] C. Gaz, A. De Luca, "**Payload estimation based on identified coefficients of robot dynamics --with an application to collision detection**," 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vancouver, CND, pp. 3033-3040, 2017 (pdf) [multimedia]. DOI:

[C-141] E. Magrini, A. De Luca, "

**Human-robot coexistence and contact handling with redundant robots**," 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vancouver, CND, pp. 4611-4617, 2017 (pdf) [multimedia]. DOI:

[C-140] G. Buondonno, J. Carpentier, G. Saurel, N. Mansard, A. De Luca, J.-P. Laumond, "

**Actuator design of compliant walkers via optimal control**," 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vancouver, CND, pp. 705-711, 2017 (pdf) [multimedia]. DOI:

[C-139] M. Khatib, K. Al Khudir, A. De Luca, "

**Visual coordination task for human-robot collaboration**," 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vancouver, CND, pp. 3762-3768, 2017 (pdf) [multimedia]. DOI:

[C-138] E. Magrini, A. De Luca, "

**Hybrid force/velocity control for physical human-robot collaboration tasks**," 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems, Daejeon, KR, pp. 857-863, 2016 (pdf) [multimedia]. DOI:10.1109/IROS.2016.7759151

[C-137] G. Buondonno, A. De Luca, "

**Combining real and virtual sensors for measuring interaction forces and moments acting on a robot**," 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems, Daejeon, KR, pp. 794-800, 2016 (pdf). DOI:10.1109/IROS.2016.7759142

[C-136] M. Geravand, E. Shahriari, A. De Luca, A. Peer "

**Port-based modeling of human-robot collaboration towards safety-enhancing energy shaping control**," 2016 IEEE International Conference on Robotics and Automation, Stockholm, SE, pp. 3075-3082, 2016 (pdf). DOI:10.1109/ICRA.2016.7487473

[C-135] C. Gaz, F. Flacco, A. De Luca, "

**Extracting feasible robot parameters from dynamic coefficients using nonlinear optimization methods**," 2016 IEEE International Conference on Robotics and Automation, Stockholm, SE, pp. 2075-2081, 2016 (pdf). DOI:10.1109/ICRA.2016.7487356

[C-134] G. Buondonno, A. De Luca, "

**A recursive Newton-Euler algorithm for robots with elastic joints and its application to control**," 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems, Hamburg, D, pp. 5526-5532, 2015 (pdf). DOI:10.1109/IROS.2015.7354160

[C-133] F. Flacco, A. De Luca, "

**Unilateral constraints in the Reverse Priority redundancy resolution method**," 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems, Hamburg, D, pp. 2564-2571, 2015 (pdf) [multimedia]. DOI:10.1109/IROS.2015.7353726

[C-132] E. Magrini, F. Flacco, A. De Luca, "

**Control of generalized contact motion and force in physical human-robot interaction**," 2015 IEEE International Conference on Robotics and Automation, Seattle, WA, pp. 2298-2304, 2015 (pdf) [multimedia]. DOI:10.1109/ICRA.2015.7139504, ICRA 2015 Best Conference Paper Award Finalist

[C-131] G. Buondonno, F. Patota, H. Wang, A. De Luca, K. Kosuge, "

**A model predictive control approach for the partner ballroom dance robot**," 2015 IEEE International Conference on Robotics and Automation, Seattle, WA, pp. 774-780, 2015 (pdf) [multimedia]. DOI:10.1109/ICRA.2015.7139266

[C-130] F. Flacco, A. De Luca, "

**A Reverse Priority approach to multi-task control of redundant robots**," 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, Chicago, IL, pp. 2421-2427, 2014 (pdf) [multimedia]. DOI:10.1109/IROS.2014.6942891

[C-129] E. Magrini, F. Flacco, A. De Luca, "

**Estimation of contact forces using a virtual force sensor**," 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, Chicago, IL, pp. 2126-2133, 2014 (pdf) [multimedia]. DOI:10.1109/IROS.2014.6942848

[C-128] F. Flacco, A. De Luca, "

**Discrete-time velocity control of redundant robots with acceleration/torque optimization properties**," 2014 IEEE International Conference on Robotics and Automation, Hong Kong, PRC, pp. 5139-5144, 2014 (pdf). DOI:10.1109/ICRA.2014.6907613

[C-127] F. Flacco, A. De Luca, "

**A pure signal-based stiffness estimation for VSA devices**," 2014 IEEE International Conference on Robotics and Automation, Hong Kong, PRC, pp. 2418-2423, 2014 (pdf). DOI:10.1109/ICRA.2014.6907195

[C-126] C. Gaz, F. Flacco, A. De Luca, "

**Identifying the dynamic model used by the KUKA LWR: A reverse engineering approach**," 2014 IEEE International Conference on Robotics and Automation, Hong Kong, PRC, pp. 1386-1392, 2014 (pdf) [software reference page]. DOI:10.1109/ICRA.2014.6907033

[C-125] F. Flacco, A. De Luca, "

**Fast redundancy resolution for high-dimensional robots executing prioritized tasks under hard bounds in the joint space**," 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, Tokyo, J, pp. 2500-2506, 2013 (pdf) [multimedia]. DOI:10.1109/IROS.2013.6696708

[C-124] M. Geravand, F. Flacco, A. De Luca, "

**Human-robot physical interaction and collaboration using an industrial robot with a closed control architecture**," 2013 IEEE International Conference on Robotics and Automation, Karlsruhe, D, pp. 4000-4007, 2013 (pdf) [multimedia]. DOI:10.1109/ICRA.2013.6631141

[C-123] F. Flacco, A. De Luca, "

**Optimal redundancy resolution with task scaling under hard bounds in the robot joint space**," 2013 IEEE International Conference on Robotics and Automation, Karlsruhe, D, pp. 3969-3975, 2013 (pdf). DOI:10.1109/ICRA.2013.6631136

[C-122] F. Flacco, A. De Luca, O. Khatib, "

**Prioritized multi-task motion control of redundant robots under hard joint constraints**," 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vilamoura, PT, pp. 3970-3977, 2012 (pdf) [multimedia]. DOI:10.1109/IROS.2012.6385619

[C-121] A. De Luca, F. Flacco, "

**Integrated control for pHRI: Collision avoidance, detection, reaction and collaboration**," 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics, Roma, I, pp. 288-295, 2012 (pdf) [multimedia]. DOI:10.1109/BioRob.2012.6290917, BioRob 2012 Best Conference Paper Award

[C-120] F. Flacco, T. Kröger, A. De Luca, O. Khatib, "

**A depth space approach to human-robot collision avoidance**," 2012 IEEE International Conference on Robotics and Automation, St. Paul, MN, pp. 338-345, 2012 (pdf) [multimedia]. DOI:10.1109/ICRA.2012.6225245

[C-119] F. Flacco, A. De Luca, O. Khatib, "

**Motion control of redundant robots under joint constraints: Saturation in the null space**," 2012 IEEE International Conference on Robotics and Automation, St. Paul, MN, pp. 285-292, 2012 (pdf) [multimedia]. DOI:10.1109/ICRA.2012.6225376

[C-118] F. Flacco, A. De Luca, I. Sardellitti, N. Tsagarakis, "

**Robust estimation of variable stiffness in flexible joints**," 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, San Francisco, CA, pp. 4026-4033, 2011 (pdf). DOI:10.1109/IROS.2011.6094604

[C-117] G. Milighetti, L. Vallone, A. De Luca, "

**Adaptive predictive gaze control of a redundant humanoid robot head**," 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, San Francisco, CA, pp. 3192-3198, 2011 (pdf) [multimedia]. DOI:10.1109/IROS.2011.6094417

[C-116] F. Flacco, A. De Luca, "

**Stiffness estimation and nonlinear control of robots with variable stiffness actuation**," 18th IFAC World Congress, Milano, I, pp. 6872-6879, 2011 (pdf). DOI:10.3182/20110828-6-IT-1002.03299

[C-115] F. Flacco, T. Kröger, A. De Luca, O. Khatib, "

**Collision avoidance in the depth space**," RSS 2011 Workshop on RGB-D: Advance Reasoning with Depth Cameras, Los Angeles, CA, 2011 (pdf).

[C-114] F. Flacco, A. De Luca, "

**Residual-based stiffness estimation in robots with flexible transmissions**," 2011 IEEE International Conference on Robotics and Automation, Shanghai, PRC, pp. 5541-5547, 2011 (pdf). DOI:10.1109/ICRA.2011.5980541

[C-113] A. De Luca, F. Flacco, "

**A PD-type regulator with exact gravity cancellation for robots with flexible joints**," 2011 IEEE International Conference on Robotics and Automation, Shanghai, PRC, pp. 317-323, 2011 (pdf). DOI:10.1109/ICRA.2011.5979615

[C-112] A. De Luca, F. Flacco, "

**Dynamic gravity cancellation in robots with flexible transmissions**," 49th IEEE Conference on Decision and Control, Atlanta, GA, pp. 288-295, 2010 (pdf). DOI:10.1109/CDC.2010.5718020

[C-111] F. Flacco, A. De Luca, "

**Multiple depth/presence sensors: Integration and optimal placement for human/robot coexistence**," 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK, pp. 3916-3923, 2010 (pdf). DOI:10.1109/ROBOT.2010.5509125

[C-110] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**Kinematic control of nonholonomic mobile manipulators in the presence of steering wheels**," 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK, pp. 1792-1798, 2010 (pdf) [multimedia]. DOI:10.1109/ROBOT.2010.5509570

[C-109] A. De Luca, F. Flacco, A. Bicchi, R. Schiavi, "

**Nonlinear decoupled motion-stiffness control and collision detection/reaction for the VSA-II variable stiffness device**," 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, St. Louis, MO, pp. 5487-5494, 2009 (pdf). DOI:10.1109/IROS.2009.5354809

[C-108] A. De Luca, R. Mattone, P. Robuffo Giordano, H.H. Bülthoff, "

**Control design and experimental evaluation of the 2D CyberWalk platform**," 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, St. Louis, MO, pp. 5051-5058, 2009 (pdf) [multimedia]. DOI:10.1109/IROS.2009.5354610, Featured also in the IEEE Spectrum Automaton blog

[C-107] A. De Luca, L. Ferrajoli, "

**A modified Newton-Euler method for dynamic computations in robot fault detection and control**," 2009 IEEE International Conference on Robotics and Automation, Kobe, J, pp. 3359-3364, 2009 (pdf). DOI:10.1109/ROBOT.2009.5152618

[C-106] L. Le Tien, A. Albu-Schäffer, A. De Luca, G. Hirzinger, "

**Friction observer and compensation for control of robots with joint torque measurements**," 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, Nice, F, pp. 3789-3795, 2008 (pdf). DOI:10.1109/IROS.2008.4651049

[C-105] S. Haddadin, A. Albu-Schäffer, A. De Luca, G. Hirzinger, "

**Collision detection and reaction: A contribution to safe physical human-robot interaction**," 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, Nice, F, pp. 3356-3363, 2008 (pdf) [multimedia]. DOI:10.1109/IROS.2008.4650764, IROS 2008 Best Application Paper Award

[C-104] A. De Luca, L. Ferrajoli, "

**Exploiting robot redundancy in collision detection and reaction**," 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, Nice, F, pp. 3299-3305, 2008 (pdf) [multimedia]. DOI:10.1109/IROS.2008.4651204

[C-103] A. De Luca, H. Panzer, "

**Rest-to-rest motion of a one-link flexible arm with smooth bang-bang torque profile**," 9th International Conference on Motion and Vibration Control, München, D, 2008 (pdf).

[C-102] S. Haddadin, A. Albu-Schäffer, A. De Luca, G. Hirzinger, "

**Evaluation of collision detection and reaction for a human-friendly robot on biological tissues**," 6th IARP/IEEE/EURON Joint Workshop on Technical Challenges for Dependable Robots in Human Environments, Pasadena, CA, 2008 (pdf).

[C-101] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**Visual servoing with exploitation of redundancy: An experimental study**," 2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, pp. 2231-2237, 2008 (pdf) [multimedia]. DOI:10.1109/ROBOT.2008.4543703

[C-100] A. Censi, D. Calisi, A. De Luca, G. Oriolo, "

**A Bayesian framework for optimal motion planning with uncertainty**," 2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, pp. 1798-1805, 2008 (pdf). DOI:10.1109/ROBOT.2008.4543469

[C-99] G. Palli, C. Melchiorri, A. De Luca, "

**On the feedback linearization of robots with variable joint stiffness**," 2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, pp. 1753-1759, 2008 (pdf). DOI:10.1109/ROBOT.2008.4543454

[C-98] P. Robuffo Giordano, A. De Luca, G. Oriolo, "

**3D structure identification from image moments**," 2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, pp. 93-100, 2008 (pdf) [multimedia]. DOI:10.1109/ROBOT.2008.4543192

[C-97] L. Zollo, B. Siciliano, A. De Luca, E. Guglielmelli, "

**PD control with on-line gravity compensation for robots with flexible links**," 2007 European Control Conference, Kos, GR, pp. 4365-4370, 2007 (pdf).

[C-96] A. De Luca, D. Schröder, M. Thümmel, "

**An acceleration-based state observer for robot manipulators with elastic joints**," 2007 IEEE International Conference on Robotics and Automation, Roma, I, pp. 3817-3823, 2007 (pdf). DOI:10.1109/ROBOT.2007.364064

[C-95] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**On-line estimation of feature depth for image-based visual servoing schemes**," 2007 IEEE International Conference on Robotics and Automation, Roma, Italy, pp. 2823-2828, 2007 (pdf) [multimedia]. DOI:10.1109/ROBOT.2007.363899

[C-94] A. De Luca, R. Mattone, P. Robuffo Giordano, "

**Acceleration-level control of the CyberCarpet**," 2007 IEEE International Conference on Robotics and Automation, Roma, I, pp. 2330-2335, 2007 (pdf) [multimedia]. DOI:10.1109/ROBOT.2007.363667

[C-93] A. De Luca, A. Albu-Schäffer, S. Haddadin, G. Hirzinger, "

**Collision detection and safe reaction with the DLR-III lightweight manipulator arm**," 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, Beijing, PRC, pp. 1623-1630, 2006 (pdf). DOI:10.1109/IROS.2006.282053

[C-92] A. De Luca, R. Mattone, P. Robuffo Giordano, "

**Feedback/feedforward schemes for motion control of the CyberCarpet**," 8th IFAC Symposium on Robot Control, Bologna, I, 2006 (pdf). DOI:10.3182/20060906-3-IT-2910.00068

[C-91] A. De Luca, R. Mattone, P. Robuffo Giordano, "

**The motion control problem for the CyberCarpet**," 2006 IEEE International Conference on Robotics and Automation, Orlando, FL, pp. 3532-3537, 2006 (pdf). DOI:10.1109/ROBOT.2006.1642241

[C-90] A. De Luca, G. Oriolo, P. Robuffo Giordano, "

**Kinematic modeling and redundancy resolution for nonholonomic mobile manipulators**," 2006 IEEE International Conference on Robotics and Automation, Orlando, FL, pp. 1867-1873, 2006 (pdf). DOI:10.1109/ROBOT.2006.1641978

[C-89] R. Mattone, A. De Luca, "

**Conditions for detecting and isolating sets of faults in nonlinear systems**," Joint 44th IEEE Conference on Decision and Control/European Control Conference 2005, Seville, E, pp. 1005-1010, 2005 (pdf). DOI:10.1109/CDC.2005.1582289

[C-88] A. De Luca, R. Mattone, "

**An identification scheme for robot actuator faults**," 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems, Edmonton, CND, pp. 1127-1131, 2005 (pdf). DOI:10.1109/IROS.2005.1545370

[C-87] R. Mattone, A. De Luca, "

**Geometric and hierarchical FDI for the IFATIS two-tank pilot plant**," 16th IFAC World Congress, Praha, CZ, pp. 394-399, 2005 (pdf). DOI:10.3182/20050703-6-CZ-1902.01868

[C-86] A. De Luca, R. Farina, P. Lucibello, "

**On the control of robots with visco-elastic joints**,'' 2005 IEEE International Conference on Robotics and Automation, Barcelona, E, pp. 4297-4302, 2005 (pdf). DOI:10.1109/ROBOT.2005.1570781

[C-85] A. De Luca, R. Mattone, "

**Sensorless robot collision detection and hybrid force/motion control**," 2005 IEEE International Conference on Robotics and Automation, Barcelona, E, pp. 999-1004, 2005 (pdf). DOI:10.1109/ROBOT.2005.1570247

[C-84] A. De Luca, R. Farina, "

**Dynamic properties and nonlinear control of robots with mixed rigid/elastic joints**," 2004 International Symposium on Robotics and Automation (2004 World Automation Congress), Seville, E, pp. 97-104, 2004 (pdf). DOI:10.1109/WAC.2004.185204

[C-83] L. Zollo, A. De Luca, B. Siciliano, "

**Regulation with on-line gravity compensation for robots with elastic joints**," 2004 IEEE International Conference on Robotics and Automation, New Orleans, LA, pp. 2687-2692, 2004 (pdf). DOI:10.1109/ROBOT.2004.1307466

[C-82] A. De Luca, R. Mattone, "

**An adapt-and-detect actuator FDI scheme for robot manipulators**," 2004 IEEE International Conference on Robotics and Automation, New Orleans, LA, pp. 4975-4980, 2004 (pdf). DOI:10.1109/ROBOT.2004.1302506

[C-81] R. Mattone, A. De Luca, "

**Detection and isolation of sensor faults in nonlinear systems: A case study**," Workshop on Advanced Control and Diagnosis, Duisburg, D, pp. 49-54, 2003 (pdf).

[C-80] M. Benosman, G. Le Vey, L. Lanari, A. De Luca, "

**Rest-to-rest motion for planar multi-link flexible manipulator**," 7th IFAC Symposium on Robot Control, Wroclaw, PL, pp. 327-332, 2003.

[C-79] L. Zollo, B. Siciliano, E. Guglielmelli, P. Dario, A. De Luca, "

**Compliance control for a robot with elastic joints**," 11th International Conference on Advanced Robotics, Coimbra, P, pp. 1411-1416, 2003 (pdf).

[C-78] A. De Luca, R. Mattone, "

**Actuator failure detection and isolation using generalized momenta**," 2003 IEEE International Conference on Robotics and Automation, Taipei, ROC, pp. 634-639, 2003 (pdf). DOI:10.1109/ROBOT.2003.1241665

[C-77] A. De Luca, S. Iannitti, "

**Smooth trajectory planning for XYnR planar underactuated robots**," 2002 IEEE/RSJ International Conference on Intelligent Robots and Systems, Lausanne, CH, pp. 1651-1656, 2002 (pdf). DOI:10.1109/IROS.2002.1043992

[C-76] A. De Luca, G. Oriolo, L. Paone, P. Robuffo Giordano, M. Vendittelli, "

**Visual-based planning and control for nonholonomic mobile robots**," 10th IEEE Mediterranean Conference on Control and Automation, Lisbon, PT, 2002 (pdf).

[C-75] A. De Luca, G. Oriolo, L. Paone, P. Robuffo Giordano, "

**Experiments in visual feedback control of a wheeled mobile robot**," 2002 IEEE International Conference on Robotics and Automation, Washington, DC, 2002 (pdf). DOI:10.1109/ROBOT.2002.1014846

[C-74] A. De Luca, S. Iannitti, "

**A simple STLC test for mechanical systems underactuated by one control**," 2002 IEEE International Conference on Robotics and Automation, Washington, DC, pp. 1735-1740, 2002 (pdf). DOI:10.1109/ROBOT.2002.1014792

[C-73] A. De Luca, R. Farina, "

**Dynamic scaling of trajectories for robots with elastic joints**," 2002 IEEE International Conference on Robotics and Automation, Washington, DC, pp. 2436-2442, 2002 (pdf). DOI:10.1109/ROBOT.2002.1013597

[C-72] A. De Luca, S. Iannitti, "

**Dynamic feedback linearization of an XYnR planar underactuated robot with n passive joints**," Journées Doctorales d'Automatique, Toulouse, F, pp. 281-287, 2001.

[C-71] A. De Luca, G. Di Giovanni, "

**Rest-to-rest motion of a two-link robot with a flexible forearm**," 2001 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, Como, I, pp. 929-935, 2001 (pdf). DOI:10.1109/AIM.2001.936795

[C-70] A. De Luca, G. Di Giovanni, "

**Rest-to-rest motion of a one-link flexible forearm**," 2001 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, Como, I, pp. 923-928, 2001 (pdf). DOI:10.1109/AIM.2001.936793

[C-69] A. De Luca, S. Iannitti, R. Mattone, G. Oriolo, "

**Control problems in underactuated manipulators**," 2001 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, Como, I, pp. 855-861, 2001 (pdf). DOI:10.1109/AIM.2001.936778

[C-68] A. De Luca, S. Iannitti, G. Oriolo, "

**Stabilization of a PR planar underactuated robot**," 2001 IEEE International Conference on Robotics and Automation, Seoul, KR, pp. 2090-2095, 2001 (pdf). DOI:10.1109/ROBOT.2001.932915

[C-67] A. De Luca, G. Oriolo, "

**Motion planning under gravity for underactuated three-link robots**," 2000 IEEE/RSJ International Conference on Intelligent Robots and Systems, Takamatsu, J, pp. 139-144, 2000 (pdf). DOI:10.1109/IROS.2000.894595

[C-66] A. De Luca, G. Oriolo, M. Vendittelli, "

**Stabilization of the unicycle via dynamic feedback linearization**," 6th IFAC Symposium on Robot Control, Vienna, A, pp. 397-402, 2000 (pdf).

[C-65] A. Bettini, A. De Luca, G. Oriolo, "

**An experimental comparison of redundancy resolution schemes**," 6th IFAC Symposium on Robot Control, Vienna, A, pp. 351-356, 2000 (pdf).

[C-64] A. De Luca, "

**Feedforward/feedback laws for the control of flexible robots**," 2000 IEEE International Conference on Robotics and Automation, San Francisco, CA, pp. 233-240, 2000 (pdf). DOI:10.1109/ROBOT.2000.844064

[C-63] A. De Luca, G. Oriolo, "

**Motion planning and trajectory control of an underactuated three-link robot via dynamic feedback linearization**," 2000 IEEE International Conference on Robotics and Automation, San Francisco, CA, pp. 2789-2795, 2000 (pdf). DOI:10.1109/ROBOT.2000.846450

[C-62] L. Caracciolo, A. De Luca, S. Iannitti, "

**Trajectory tracking control of a four-wheel differentially driven mobile robot**," 1999 IEEE International Conference on Robotics and Automation, Detroit, MI, pp. 2632-2638, 1999 (pdf). DOI:10.1109/ROBOT.1999.773994

[C-61] A. De Luca, G. Oriolo, "

**Stabilization of the Acrobot via iterative state steering**," 1998 IEEE International Conference on Robotics and Automation, Leuven, B, pp. 3581-3587, 1998 (pdf). DOI:10.1109/ROBOT.1998.681023

[C-60] A. De Luca, S. Panzieri, G. Ulivi, "

**Stable inversion control for flexible link manipulators**," 1998 IEEE International Conference on Robotics and Automation, Leuven, B, pp. 799-805, 1998 (pdf). DOI:10.1109/ROBOT.1998.677083

[C-59] A. De Luca, P. Lucibello, "

**A general algorithm for dynamic feedback linearization of robots with elastic joints**," 1998 IEEE International Conference on Robotics and Automation, Leuven, B, pp. 504-510, 1998 (pdf). DOI:10.1109/ROBOT.1998.677024, ICRA 1998 Best Conference Paper Award

[C-58] A. De Luca, R. Mattone, G. Oriolo, "

**Stabilization of underactuated robots: Theory and experiments for a planar 2R manipulator**," 1997 IEEE International Conference on Robotics and Automation, Albuquerque, NM, pp. 3274-3280, 1997 (pdf). DOI:10.1109/ROBOT.1997.606788

[C-57] A. De Luca, R. Mattone, G. Oriolo, "

**Control of underactuated mechanical systems: Application to the planar 2R robot**," 35th IEEE Conference on Decision and Control, Kobe, J, pp. 2614-2619, 1996 (pdf). DOI:10.1109/CDC.1996.572718

[C-56] A. De Luca, R. Mattone, "

**Controllability through active forces in cooperating robots with general payloads**," 13th IFAC World Congress, San Francisco, CA, vol. A, pp. 13-18, 1996 (pdf).

[C-55] R. Mattone, A. De Luca, "

**Task-oriented dynamic modeling of two cooperating robots**," 6th International Symposium on Robotics and Manufacturing, Montpellier, F, vol. 6, pp. 503-510, 1996 (pdf).

[C-54] A. De Luca, R. Mattone, G. Oriolo, "

**Dynamic mobility of redundant robots using end-effector commands**," 1996 IEEE International Conference on Robotics and Automation, Minneapolis, MN, pp. 1760-1767, 1996 (pdf). DOI:10.1109/ROBOT.1996.506967

[C-53] A. Bemporad, A. De Luca, G. Oriolo, "

**Local incremental planning for a car-like robot navigating among obstacles**," 1996 IEEE International Conference on Robotics and Automation, Minneapolis, MN, pp. 1205-1211, 1996 (pdf). DOI:10.1109/ROBOT.1996.506871

[C-52] A. De Luca, "

**Decoupling and feedback linearization of robots with mixed rigid/elastic joints**," 1996 IEEE International Conference on Robotics and Automation, Minneapolis, MN, pp. 816-821, 1996 (pdf). DOI:10.1109/ROBOT.1996.503874

[C-51] A. De Luca, L. Lanari, "

**Robots with elastic joints are linearizable via dynamic feedback**," 34th IEEE Conference on Decision and Control, New Orleans, LA, pp. 3895-3897, 1995 (pdf). DOI:10.1109/CDC.1995.479209

[C-50] A. De Luca, R. Mattone, "

**Modeling and control for cooperating robots handling objects with extra degrees of freedom**," 3rd European Control Conference, Roma, I, pp. 1924-1931, 1995.

[C-49] A. De Luca,

**"Dynamic feedback linearization of robots with mixed rigid/elastic joints**," 3rd European Control Conference, Roma, I, pp. 1863-1869, 1995.

[C-48] A. De Luca, R. Mattone, M. Sciandrone, "

**Direct kinematics of articulated parallel manipulators using neural networks**," 3rd IEEE Mediterranean Symposium on New Directions in Control and Automation, Limassol, CY, pp. 53-59, 1995 (pdf).

[C-47] A. De Luca, R. Mattone, "

**Modeling and control alternatives for robots in dynamic cooperation**," 1995 IEEE International Conference on Robotics and Automation, Nagoya, J, pp. 138-145, 1995 (pdf). DOI:10.1109/ROBOT.1995.525276

[C-46] A. De Luca, G. Oriolo, "

**Nonholonomy in redundant robots under kinematic inversion**," 4th IFAC Symposium on Robot Control, Capri, I, pp. 179-184, 1994.

[C-45] A. De Luca, G. Oriolo, "

**Local incremental planning for nonholonomic mobile robots**," 1994 IEEE International Conference on Robotics and Automation, San Diego, CA, pp. 104-110, 1994 (pdf). DOI:10.1109/ROBOT.1994.351003

[C-44] A. De Luca, S. Panzieri, "

**An iterative scheme for learning gravity compensation in flexible robot arms**," 12th IFAC World Congress, Sydney, AUS, vol. 8, pp. 191-196, 1993 (pdf).

[C-43] A. De Luca, B. Siciliano, "

**An asymptotically stable joint PD controller for robot arms with flexible links under gravity**," 31st IEEE Conference on Decision and Control, Tucson, AZ, pp. 325-326, 1992 (pdf). DOI:10.1109/CDC.1992.371728

[C-42] A. De Luca, M.D. Di Benedetto, "

**Some structural aspects in the control of nonholonomic systems via dynamic compensation**," 2nd IFAC Workshop on System Structure and Control, Praha, CZ, pp. 240-243, 1992.

[C-41] A. De Luca, F. Nicolò, G. Ulivi, "

**Trajectory tracking in flexible robot arms**," in A. Isidori, T.J. Tarn (Eds.)

*Systems, Models and Feedback: Theory and Applications*(Proc. U.S.-Italy Workshop in honor of Professor Antonio Ruberti, Capri, I, June 1992), Progress in Systems and Control Theory Series, vol. 12, pp. 17-34, Birkhäuser, Boston, 1992 (pdf).

[C-40] A. De Luca, L. Lanari, G. Oriolo, "

**Control of redundant robots on cyclic trajectories**," 1992 IEEE International Conference on Robotics and Automation, Nice, F, pp. 500-506, 1992 (pdf). DOI:10.1109/ROBOT.1992.220231

[C-39] A. De Luca, G. Ulivi, "

**Iterative learning control of robots with elastic joints**," 1992 IEEE International Conference on Robotics and Automation, Nice, F, pp. 1920-1926, 1992 (pdf). DOI:10.1109/ROBOT.1992.219948

[C-38] A. De Luca, B. Siciliano, "

**Relevance of dynamic models in analysis and synthesis of control laws for flexible manipulators**," in J.C. Gentina, S.G. Tsafestas (Eds.)

*Robotics and Flexible Manufacturing Systems*, pp. 161-168, Elsevier, Amsterdam, 1992.

[C-37] A. De Luca, G. Oriolo, "

**Issues in acceleration resolution of robot redundancy**," 3rd IFAC Symposium on Robot Control, Vienna, A, pp. 665-670, 1991 (pdf).

[C-36] A. De Luca, C. Manes, "

**Hybrid force-position control for robots in contact with dynamic environments**," 3rd IFAC Symposium on Robot Control, Vienna, A, pp. 177-182, 1991.

[C-35] A. De Luca, B. Siciliano, "

**Issues in modeling techniques for control of robotic manipulators with structural flexibility**," 13th IMACS World Congress on Computation and Applied Mathematics, Dublin, IR, vol. 3, pp. 1121-1122, 1991.

[C-34] A. De Luca, "

**Nonlinear regulation of robot motion**," 1st European Control Conference, Grenoble, F, pp. 1045-1050, 1991.

[C-33] A. De Luca, C. Manes, "

**On the modeling of robots in contact with a dynamic environment**," 5th International Conference on Advanced Robotics, Pisa, I, pp. 568-574, 1991 (pdf). DOI:10.1109/ICAR.1991.240592, ICAR 1991 Best Student Paper Award

[C-32] A. De Luca, F. Mataloni, "

**Learning control for redundant manipulators**," 1991 IEEE International Conference on Robotics and Automation, Sacramento, CA, pp. 1442-1450, 1991 (pdf). DOI:10.1109/ROBOT.1991.131818

[C-31] A. De Luca, L. Lanari, "

**Achieving minimum phase behavior in a one-link flexible arm**," International Symposium on Intelligent Robotics, Bangalore, IND, pp. 224-235, 1991 (pdf).

[C-30] A. De Luca, "

**Zero dynamics in robotic systems**," in C.I. Byrnes, A. Kurszanski (Eds.)

*Nonlinear Synthesis*(Proc. IIASA Workshop, Sopron, H, June 1989), Progress in Systems and Control Theory Series, vol. 9, pp. 68-87, Birkhäuser, Boston, 1991 (pdf). DOI:10.1007/978-1-4757-2135-5_5

[C-29] A. De Luca, L. Lanari, G. Ulivi, "

**End-effector trajectory tracking in flexible arms: Comparison of approaches based on regulation theory**," in C. Canudas de Wit (Ed.)

*Advanced Robot Control*, Lecture Notes in Control and Information Sciences, vol. 162, pp. 190-206, Springer Verlag, Berlin, 1991 (pdf). DOI:10.1007/BFb0039272

[C-28] A. De Luca, L. Lanari, G. Ulivi, "

**Nonlinear regulation of end-effector motion for a flexible robot arm**," in G. Conte, A.M. Perdon, B. Wyman (Eds.)

*New Trends in Systems Theory*(Proc. Università di Genova-The Ohio State University Joint Conference, Genova, I, July 1990), Progress in Systems and Control Theory Series, vol. 7, pp. 229-236, Birkhäuser, Boston, 1991 (pdf). DOI:10.1007/978-1-4612-0439-8_28

[C-27] A. De Luca, B. Siciliano, "

**Explicit dynamic modeling of a planar two-link flexible manipulator**," 29th IEEE Conference on Decision and Control, Honolulu, HI, pp. 528-530, 1990 (pdf). DOI:10.1109/CDC.1990.203652

[C-26] A. De Luca, L. Lanari, P. Lucibello, S. Panzieri, G. Ulivi, "

**Control experiments on a two-link robot with a flexible forearm**," 29th IEEE Conference on Decision and Control, Honolulu, HI, pp. 520-527, 1990 (pdf). DOI:10.1109/CDC.1990.203651

[C-25] A. De Luca, G. Oriolo, "

**The reduced gradient method for solving redundancy in robot arms**," 11th IFAC World Congress, Tallinn, USSR, vol. 9, pp. 143-148, 1990.

[C-24] A. De Luca, G. Oriolo, "

**Kinematic resolution of redundancy via joint-space decomposition**," 8th CISM-IFToMM Symposium on Theory and Practice of Robots and Manipulators, Krakow, PL, pp. 64-71, 1990 (pdf).

[C-23] A. De Luca, L. Lanari, G. Ulivi, "

**Output regulation of a flexible robot arm**," in A. Bensoussan, J.L. Lyon (Eds.)

*Analysis and Optimization of Systems*(Proc. 9th INRIA International Conference on Analysis and Optimization of Systems, Antibes, F, June 1990), Lecture Notes in Control and Information Sciences, vol. 144, pp. 833-842, 1990 (pdf). DOI:10.1007/BFb0120104

[C-22] A. De Luca, G. Oriolo, "

**Efficient dynamic resolution of robot redundancy**," 1990 American Control Conference, San Diego, CA, pp. 221-227, 1990 (pdf).

[C-21] A. De Luca, B. Siciliano, "

**Dynamic modelling of multi-link flexible robot arms**," IFIP Conference on Modelling the Innovation, Roma, I, pp. 193-200, 1990.

[C-20] A. De Luca, C. Manes, G. Ulivi, "

**Robust hybrid dynamic control of robot arms**," 28th IEEE Conference on Decision and Control, Tampa, FL, pp. 2641-2646, 1989 (pdf). DOI:10.1109/CDC.1989.70658

[C-19] A. De Luca, G. Paesano, G. Ulivi, "

**A frequency-domain approach to learning control: Implementation for a robot manipulator**," 4th IEEE International Symposium on Intelligent Control, Albany, NY, pp. 66-71, 1989 (pdf). DOI:10.1109/ISIC.1989.238715

[C-18] A. De Luca, G. Ulivi, "

**The design of linearizing outputs for induction motors**," IFAC Symposium on Nonlinear Control Systems Design, Capri, I, pp. 363-367, 1989.

[C-17] A. De Luca, P. Lucibello, G. Ulivi, "

**Inversion techniques for open and closed-loop control of flexible arms**," 2nd International Symposium on Robotics and Manufacturing, Albuquerque, NM, pp. 529-538, 1988.

[C-16] A. De Luca, L. Lanari, G. Oriolo, F. Nicolò, "

**A sensitivity approach to optimal spline robot trajectories**," 2nd IFAC Symposium on Robot Control, Karlsruhe, D, pp. 505-510, 1988 (pdf).

[C-15] A. De Luca, C. Manes, F. Nicolò, "

**A task space decoupling approach to hybrid control of manipulators**," 2nd IFAC Symposium on Robot Control, Karlsruhe, D, pp. 157-162, 1988.

[C-14] A. De Luca, C. Manes, F. Nicolò, "

**Hybrid force-velocity control using redundant manipulators**," NATO Advanced Research Workshop on Robots with Redundancy: Design, Sensing and Control, Salò, I, 1988.

[C-13] A. De Luca, G. Ulivi, "

**Dynamic decoupling of voltage frequency controlled induction motors**," in A. Bensoussan, J.L. Lyon (Eds.)

*Analysis and Optimization of Systems*(Proc. 8th International Conference on Analysis and Optimization of Systems, Nice, F, June 1988), Lecture Notes in Control and Information Sciences, vol. 111, pp. 127-137, 1988 (pdf). DOI:10.1007/10.1007/BFb0042208

[C-12] A. De Luca, B. Siciliano, "

**Joint-based control of a nonlinear model of a flexible arm**," 1988 American Control Conference, Atlanta, GA, pp. 935-940, 1988 (pdf).

[C-11] A. De Luca, "

**Dynamic control of robots with joint elasticity**," 1988 IEEE International Conference on Robotics and Automation, Philadelphia, PA, pp. 152-158, 1988 (pdf). DOI:10.1109/ROBOT.1988.12040 (Note: Also in M.W. Spong, F. Lewis, C.T. Abdallah (Eds.)

*Robot Control: Dynamics, Motion Planning, and Analysis*, IEEE Press, New York, 1993)

[C-10] A. De Luca, P. Lucibello, F. Nicolò, "

**Automatic symbolic modelling and nonlinear control of robots with flexible links**," IEE International Workshop on Robot Control: Theory and Applications, Oxford, GB, pp. 62-70, 1988.

[C-9] A. De Luca, G. Ulivi, "

**Full linearization of induction motors via nonlinear state-feedback**," 26th IEEE Conference on Decision and Control, Los Angeles, CA, pp. 1765-1770, 1987 (pdf). DOI:10.1109/CDC.1987.272793

[C-8] A. De Luca, A. Isidori, "

**Feedback linearization of invertible systems**," 2nd Duisburger Kolloquium Automation und Robotik, Duisburg, D, Jul. 1987.

[C-7] A. De Luca, "

**Control properties of robot arms with joint elasticity**," 8th International Symposium on the Mathematical Theory of Networks and Systems, Phoenix, AZ, pp. 61-70, 1987.

[C-6] A. Isidori, C.H. Moog, A. De Luca, "

**A sufficient condition for full linearization via dynamic state feedback**," 25th IEEE Conference on Decision and Control, Athens, GR, pp. 203-208, 1986 (pdf). DOI:10.1109/CDC.1986.267208

[C-5] A. De Luca, G. Di Pillo, "

**An exact augmented Lagrangian approach to multilevel optimization**," 4th IFAC/IFORS Symposium on Large Scale Systems: Theory and Applications, Zürich, CH, pp. 398-404, 1986.

[C-4] A. De Luca, A. Isidori, F. Nicolò, "

**Control of robot arm with elastic joints via nonlinear dynamic feedback**," 24th IEEE Conference on Decision and Control, Ft. Lauderdale, FL, pp. 1671-1679, 1985 (pdf). DOI:10.1109/CDC.1985.268819

[C-3] A. De Luca, F. Nicolò, "

**Minimum traveling time for robot arm under joints dynamic constraints**," 1st IFAC Symposium on Robot Control, Barcelona, E, pp. 361-363, 1985.

[C-2] A. De Luca, A. Isidori, F. Nicolò, "

**An application of nonlinear model matching to the dynamic control of robot arm with elastic joints**," 1st IFAC Symposium on Robot Control, Barcelona, E, pp. 55-61, 1985.

[C-1] P. Caravani, A. De Luca, "

**Some results in sectoral aggregation**," 6th Polish-Italian Symposium on System Theory and Mathematical Economics, Roma, I, pp. 109-129, 1984.

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