Planning fine motion strategies by reasoning in the contact space

The author describes a method for planning fine motion strategies by reasoning on an explicit representation of the contact space. This method reduces the algorithmic complexity inherent in the path planning problem by separating the computation of potential reachable positions and valid movements from the determination of those that are really executable by the robot. The algorithm developed operates in two phases: the construction of a state graph representing a set of potential solutions; and the searching of this graph in order to find a good reverse path defining a feasible fine motion program. The fine motion planner has been implemented in LUCID-LISP on a SUN 260. Simulations have given rise to real executions using a six-degree-of-freedom SCEMI robot equipped with a force sensor