Composite Models for Mobile Robot Offline Path Planning

Abstract

As new technological achievements take place in the robotic hardware field, an increased level of intelligence is required as well. The most fundamental intelligent task for a mobile robot is the ability to plan a valid path from its initial to terminal configurations while avoiding all obstacles located on its way. The robot motion planning problem came into existence in early 70’s and evolved to a vast and active research discipline as it is today. Numerous solution methods have been developed for robot motion planning since then, many of them being variations of a few general approaches: Roadmap, Cell Decomposition, Potential Fields, mathematical programming, and heuristic methods. Most classes of motion planning problems can be solved using these approaches, which are broadly surveyed in (Latombe, 1991), (Hwang & Ahuja, 1992), and (Choset et al., 2005). This chapter introduces two new offline path planning models which are founded on the Roadmap and Potential Fields classic motion planning approaches. These approaches have their unique characteristics and strategies for solving motion planning problems. In fact, each one has its own advantage that excels others in certain aspects. For instance, the Visibility Graph yields the shortest path; but its computational time exceeds other methods. Or, while the Voronoi Diagram plans the safest path and is easy to calculate in 2D, it often produces overly lengthy paths, and yields poor results in higher space dimensions. On the other hand, Potential Fields are easy to compute and are suitable for high dimensional problems, but they suffer from the local minima problem, and the oscillating paths generated near narrow passages of configuration space reduce their efficiency. A brief review on these underlying methods is given in this section. In order to benefit from the strong aspects of these classic path planning methods and compensate their drawbacks, a policy of combining these basic approaches into single architectures is adopted. In devising the new planners it is intended to aggregate the superiorities of these methods and work out efficient and reliable composite algorithms for robot motion planning.