Showing papers by "Jean-Paul Laumond published in 1999"

Visibility based probabilistic roadmaps

Abstract: Presents a variant of probabilistic roadmap algorithms that appeared as a promising approach to motion planning. We exploit a free-space structuring of the configuration space into visibility domains in order to produce small roadmaps. The algorithm has been implemented within a software platform allowing us to address a large class of mechanical systems. Experiments show the efficiency of the approach in capturing narrow passages of collision-free configuration spaces.

Motion planning and control for Hilare pulling a trailer

Abstract: This paper deals with motion planning and control for mobile robots. The various components of an integrated architecture for the mobile robot Hilare pulling a trailer are presented. The nonholonomic path planner is based on an original steering method accounting for the small-time controllability of the system. Then the path is transformed into a trajectory by including the dynamical constraints of the system (bounded velocity and bounded acceleration). Finally, the motion control is addressed. Due to the geometric transformation for a virtual robot, we show how to reduce the problem to a classical approach of trajectory tracking for a mobile robot moving forward only. The experimental results presented include two types of robot-trailer connection systems.

Multiple path coordination for mobile robots: a geometric algorithm

Abstract: This paper presents a geometric based approach for multiple mobile robot motion coordination. All the robot paths being computed independently, we address the problem of coordinating the motion of the robots along their own path in such a way they do not collide each other. The proposed algorithm is based on a bounding box representation of the obstacles in the so-called coordination diagram. The algorithm is resolution-complete. Its efficiency is illustrated by examples involving more than 100 robots.

Obstacle distance for car-like robots

Abstract: This paper shows how to compute the nonholonomic distance between a pointwise 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 /spl Lscr/) 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's car) or only forward (Dubins' car). They are based on the convexity analysis of the reachable set.

Steering nonholonomic systems via nilpotent approximations: the general two-trailer system

Abstract: Existing methods for nonholonomic motion planning can only be applied to exactly nilpotentizable or flat systems. For nonholonomic systems that do not fall into the above classes, we conjecture that globally defined nilpotent approximations will allow the synthesis of efficient steering and stabilization strategies. In the paper, a car towing two off-hooked trailers is considered as a case study. First, it is shown how to derive a nilpotent approximation that is valid in the neighborhood of both regular and singular points. Then, such approximate model is used to compute steering controls. Simulation results are reported to show the satisfactory performance of the method.

Mobility analysis for feasibility studies in CAD models of industrial environments

Abstract: Presents a variant of a probabilistic approach to motion planning. The objective is to face large, complex industrial environments for maintenance purpose. The contribution is based on a structuring of the workspace into boxes that limits the size of the graph to be searched. The algorithm was integrated in a commercial CAD system and real-size experiments are presented.