Proximity sensing in robot manipulator motion planning: system and implementation issues

Results of one effort to implement a motion planning system for a robot arm operating in an uncertain environment are discussed. It is known that path planning algorithms with proven convergence can be designed for some planar and three-dimensional robot arm manipulators operating among unknown obstacles of arbitrary shapes. The attractiveness of such systems lies in their ability to operate in a complex, perhaps even time-varying, unstructured environment. Implementation of these algorithms, however, presents a variety of hardware and algorithmic problems related to: covering the arm with arrays of sensors to form a sensitive skin; processing real-time sensor data; designing complementary algorithms for step-by-step motion planning based on limited local information; and integrating these components, together with global planning algorithms, in a single system. The authors discuss various tradeoffs and solutions implemented in the sensor-based planning system for a planar arm manipulator developed in their laboratory and present a summary of their experiments with it.>