Publications
International
Journals
- P.
Robuffo Giordano, M. Vendittelli, "Shortest paths to obstacles for
a polygonal Dubins car," to appear in the
IEEE Transactions on Robotics, DOI:
10.1109/TRO.2008.2011421, 2009.
- A.
Franchi, L. Freda, G. Oriolo, M.
Vendittelli, "The SRG Method: A Decentralized
Strategy for Cooperative Robot Exploration,"
IEEE/ASME Transactions on
Mechatronics, vol. 14, no. 2,
pp. 163-175, 2009.
- P.
Robuffo Giordano, M. Vendittelli, J.-P.
Laumond, P. Soueres, "Nonholonomic distance to
polygonal obstacles for a car-like robot of polygonal shape,"
IEEE Transactions on Robotics, vol. 22, no. 5,
pp. 1040-1047, 2006 (pdf).
This paper shows how to compute the nonholonomic distance between a
polygonal car-like robot and polygonal obstacles. The solution extends
previous work of Reeds and Shepp by finding the shortest path to a
manifold (rather than to a point) in configuration space. Based on
optimal control theory, the proposed approach yields an analytic
solution to the problem.
- G. Oriolo, M. Vendittelli, "A stabilization
framework for
general nonholonomic systems with an application to the plate-ball
mechanism," IEEE Transactions on Robotics, vol. 21, no. 2,
pp. 162-175, 2005 (pdf).
We present a framework for the stabilization of nonholonomic systems
that do not possess special properties such as flatness or exact
nilpotentizability. Our approach makes use of two tools: an
iterative control scheme and a nilpotent approximation of the system
dynamics. The latter is used to compute an
approximate steering control which, repeatedly applied to the system,
guarantees asymptotic stability with exponential
convergence to any desired set-point, under appropriate conditions. For
illustration, we apply the proposed strategy to design a
stabilizing controller for the plate-ball manipulation system, a
canonical example of non-flat nonholonomic mechanism. The theoretical
performance and robustness of the algorithm are confirmed by
simulations, both in the nominal case and in the presence of a
perturbation on the ball radius.
- M.
Vendittelli, G. Oriolo, F. Jean, J.-P. Laumond, "Nonhomogeneous
nilpotent
approximations for nonholonomic systems with singularities," IEEE
Transactions on Automatic Control, vol. 49 , no. 6
, pp. 261 - 266, 2004 (pdf).
Nilpotent approximations are a useful tool for analyzing and
controlling
systems whose tangent linearization does not preserve controllability,
such as nonholonomic mechanisms. However conventional homogeneous
approximations
exhibit a drawback: in the neighborhood o singular points (where the
system
growth vector is not constant) the vector fields of the approximate
dynamics
do not vary continuously with the approximation point. The geometric
counterpart
of this situation is that the sub-Riemannian distance estimate provided
by the classical Ball-Box Theoremis not uniform at singular points.
With
reference to a specific family of driftless systems, we show how to
build
a nonhomogeneous nilpotent approximation whose vector fields vary
continuously
around singular points. It is also proven that the privileged
coordinates
associated to such an approximation provide a uniform estimate of the
distance.
- A. De
Luca, M. Vendittelli, ... , G. Ulivi,
"Construction, training and clinical validation of an interpretation
system for genotypic HIV-1 drug resistance based on fuzzy rules revised
by virological outcomes," Antiviral Therapy, vol. 9, no. 4, 2004.
- 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.
- M.
Vendittelli, J.P. Laumond, C. Nissoux, "Obstacle distance for car-like
robots," IEEE Transactions on Robotics and Automation, vol. 15, no. 4,
pp. 678-691, 1999 (compressed
Postscript version).
This paper shows how to compute the nonholonomic distance between
a point-wise car-like robot and polygonal obstacles. Geometric
constructions
to compute the shortest paths from a configuration (given orientation
and
position in the plane of the robot) to a position (i.e., a
configuration
with unspecified final orientation) are first presented. The geometric
structure of the reachable set (set of points in the plane reachable by
paths of given length l) is then used to compute the shortest paths to
straight-line segments. Obstacle distance is defined as the length of
such
shortest paths. The algorithms are developed for robots that can move
both
forward and backward (Reeds and Shepp car) or only forward (Dubins
car).
They are based on the convexity analysis of the reachable
set.
- G.Oriolo,
G.Ulivi, M.Vendittelli, "Real-time map building and navigation
for autonomous robots in unknown environments," IEEE Transactions on
Systems,
Man, and Cybernetics. Part B: Cybernetics, vol. 28, no. 3, pp. 316-333,
1998 (compressed
Postscript version).
An algorithmic method is presented for the problem of autonomous
robot motion in completely unknown environments. Our approach is based
on the alternate execution of two fundamental processes: map building
and
navigation. In the former, range measures are collected through the
robot
exteroceptive sensors and processed in order to build a local
representation
of the surrounding area. This representation is then integrated in the
global map so far reconstructed by filtering out insufficient or
conflicting
information. In the navigation phase, an A*-based planner generates a
local
path from the current robot position to the goal, that is safe inside
the
visited area and proposes directions for further exploration. The robot
follows the path up to the boundary of the visited area, terminating
its
motion if unexpected obstacles are encountered. The most peculiar
aspects
of our method are (i) the use of fuzzy logic to build an environment
map
that is very efficiently computed and modified, and (ii) the iterative
application of A*, that is a complete planning algorithm taking full
advantage
local information. Experimental results of the implementation on a
NOMAD
200 mobile robot show that the proposed method provides real-time
performance
both in static and moderately dynamic environments.
- G.
Oriolo, G. Ulivi, M. Vendittelli, "Fuzzy maps: A new tool for mobile
robot perception and planning," Journal of Robotic Systems, vol. 14,
no.
3, pp. 179-197, 1997 (compressed
Postscript version).
An essential component of an autonomous mobile robot is the
exteroceptive
sensory system. Sensing capabilities should be integrated with a method
for extracting a representation of the environment from uncertain
sensor
data and with an appropriate planning algorithm. In this paper, fuzzy
logic
concepts are used to introduce a tool useful for robot perception as
well
as for planning collision-free motions. In particular, a map of the
environment
is defined as the fuzzy set of unsafe points, whose membership function
quantifies the possibility for each point to belong to an obstacle. The
computation of this set is based on a specific sensor model and makes
use
of intermediate sets generated from range measures and aggregated by
means
of fuzzy set operators. This general approach is applied to a robot
with
ultrasonic rangefinders. The resulting map building algorithm performs
well, as confirmed by a comparison with stochastic methods. The
planning
problem on fuzzy maps can be solved by defining various path cost
functions,
corresponding to different strategies, and by searching the map for
optimal
paths. To this end, proper instances of the A* algorithm are devised.
Experimental
results for a Nomad 200 robot moving in a real-world environment are
presented.
- G.
Oriolo, G. Ulivi, M. Vendittelli "Path planning for mobile robots via
skeletons on fuzzy maps," Intelligent Automation and Soft Computing,
vol.
2, no. 4, pp. 355-374, 1996.
We present algorithms for robot path planning via navigation functions
on fuzzy maps. In this kind of bitmaps, a number is associated to each
cell, characterizing the possibility that it belongs to an obstacle.
Such
a representation is useful when unknown environments are reconstructed
from sensor measures. Two methods are devised: both are based on a
proper
modification of the wavefront expansion algorithm. The first is
relatively
simple, but produces paths that may graze the obstacles. Instead, the
second
method makes use of a properly defined skeleton of the map, that lies
as
far as possible from such areas. The performance of the two methods is
illustrated by application to both simulated and experimental maps. The
proposed method is also extended to the case of nonholonomic wheeled
mobile
robots.
- M.
Poloni, G. Ulivi, M. Vendittelli, "Fuzzy logic and autonomous vehicles:
Experiments in ultrasonic vision," Fuzzy Sets and Systems, no. 69, pp.
15-27, 1995.
The opportunities offered by fuzzy logic to build maps for robot
navigation are investigated. Characteristics of points of the space
(occupied,
free, uncertain, etc.) are easily expressed trough set theoretical
operations.
Real world experiments validate the approach. The experimental set-up
is
based on modified Polaroid ultrasonic sensors, however the approach can
be easily extended to incorporate other kinds of sensors.
Book
Chapters
A.
De Luca, G. Oriolo, M. Vendittelli, S. Iannitti "Planning motions for
robotic systems subject to differential constraints," to appear in
MISTRAL
- Methodologies and Integration of Subsystems and Technologies for
Anthropic
Robots and Locomotion, B. Siciliano, G. Casalino, A. De Luca and C.
Melchiorri,
Eds., Springer, 2003.
A. De
Luca, G. Oriolo, M. Vendittelli, "Control of wheeled mobile robots:
An experimental overview," in RAMSETE - Articulated and Mobile Robotics
for Services and Technologies, S. Nicosia, B. Siciliano, A. Bicchi, P.
Valigi Eds., Springer-Verlag, 2001 (pdf).
G. Oriolo, G.
Ulivi, M. Vendittelli, "Chapter 9: Fuzzy maps: Managing uncertainty
in sensor-based motion planning," Applications of Fuzzy Logic: Toward
High
Machine Intelligence Quotient Systems, M. Jamshidi Ed., pp. 175-199,
Prentice-Hall,
1997.
International
Conferences