MANIPULATION PLANNING FOR REDUNDANT ROBOTS - A PRACTICAL APPROACH

An emerging paradigm in solving the classical motion-planning problem (among static obstacles) is to capture the connectivity of the configu ration space using a finite (but possibly large) set of landmarks (or nodes) in it. In this paper we extend this paradigm to manipulation-pl anning problem, where the goal is to plan the motion of a robot so tha t it can move a given object from an initial configuration to a final configuration while avoiding collisions with the static obstacles and other movable objects in the environment. Our specific approach adapts Adriadne's clew algorithm which has been shown effective for classica l motion-planning problems (Mazer et al. 1994; Ahuactzin 1994). In our approach, landmarks are placed in lower dimensional submanifolds of t he composite configuration space. These landmarks represent stable gra sps that are reachable from the initial configuration. From each new l andmark, the planner attempts to reach the goal configuration by execu ting a local planner again in a lower (but different) dimensional subm anifold of the composite configuration space. The approach is probabil istically resolution complete, does not assume that a closed-form inve rse-kinematics solution for the manipulator is available, and is parti cularly suitable for redundant manipulators. We also demonstrate that our approach is practical for realistic problems in three-dimensional environments with manipulator arms having fairly large numbers of degr ees of freedom. We have experimented with this approach for a 7-DOF ma nipulator in 3-D environments with one movable object, and computation times range between a few minutes and a few tens of minutes-in our ex periments, between 3 min to 15 min, depending on the task difficulty.