Motion feasibility of a wheeled vehicle with a steering angle limit

Self Cite

An important concept proposed in the early stage of robot path planning field is the shrinking of the robot to a point and meanwhile expanding of the obstacles in the workspace as a set of new obstacles. The resulting grown obstacles are called the Configuration Space (Cspace) obstacles. The find-path problem is then transformed into that of finding a collision free path for a point robot among the Cspace obstacles. However, the research experiences obtained so far have shown that the calculation of the Cspace obstacles is very hard work when the following situations occur: 1. both the robot and obstacles are not polygons and 2. the robot is allowed to rotate. This situation is even worse when the robot and obstacles are three dimensional (3D) objects with various shapes. Obviously a direct path planning approach without the calculation of the Cspace obstacles is strongly needed. This paper presents such a new real-time robot path planning approach which, to the best of our knowledge, is the first one in the robotic community. The fundamental ideas are the utilization of inequality and optimization technique. Simulation results have been presented to show its merits.

“…Note that the former is a special case of the latter, and the latter can not be converted into the former. For more details, see references [32,44,45].…”

Section: Semi-infinite Constrained Optimization (Sico)mentioning

confidence: 99%

A real-time path planning approach without the computation of Cspace obstacles

Wang

Liu

et al. 2004

Self Cite

“…This study was done in the context of the HILARE mobile robot project. 45 Wang, Linnett and Roberts 46,47 investigate the feasible movements of a three wheel vehicle with a steering angle limitation, and point out the types of kinematic restrictions that should be taken into account in path planning. Their work concludes with a generic formulation of the problem of path planning, and the presentation of a generic algorithm, which is used to find an approximate optimal global path and also to evaluate potential collision with polygonal obstacles.…”

Section: Research On Car-like Robotsmentioning

confidence: 99%

Nonholonomic path planning among obstacles subject to curvature restrictions

Esquivel

Chiang²

2002

This paper addresses the problem of finding a nonholonomic path subject to a curvature restriction, to be tracked by a wheeled autonomous navigation vehicle. This robot is able to navigate in a structured environment, with obstacles modeled as polygons, thus constituting a model based system. The path planning methodology begins with the conditioning of the polygonal environment by offsetting each polygon in order to avoid the possibility of collision with the mobile. Next, the modified polygonal environment is used to compute a preliminary shortest path (PA) between the two extreme positions of the trajectory in the plane (x, y). This preliminary path (PA) does not yet consider the restrictions on the curvature and is formed only by straight line segments. A smoothing process follows in order to obtain a path (PS) that satisfies curvature restrictions which consist basically of joining the straight line segments by circular arcs of minimum radius R (filleting). Finally, the initial and final orientation of the vehicle are accounted for. This is done using a technique we have called the Star Algorithm, because of the geometric shape of the resulting maneuvers. A final complete path (PC) is thus obtained.

“…(iii) Most of the previous work deals only with front steering systems, not four wheeled tractor/trailer steering systems. 3,[5][6][7]10,11 Previous work by one of the authors of this paper [12][13][14] has shown that for developing a practical trajectory the steering angle limit must be considered. In reference 15 it is shown that trajectory generation for a system with nonholonomic constraints, such as a rigid vehicle or a space hopping robot, can be converted into a polynomial fitting problem.…”

Section: Introductionmentioning

confidence: 97%

Trajectory generation for a four wheel steering tractor-trailer system: a two-step method

Wang

Cartmell

1998

Self Cite

A basic problem in the development of an intelligent vehicle/highway system (IVHS), or an autonomous mobile robot system (AMRS) is to find suitable input controls which can be used to drive the vehicle between any two configurations. In this paper a trajectory generation problem for a four-wheel-steering tractor/semi-trailer system is investigated, and it is shown that this nonholonomic constraint problem can be converted into one of finding fitting-functions satisfying certain necessary boundary conditions. Proposals for control laws are presented and simulation results for a lane change manoeuvre are given.