Identifying contact formations in the presence of uncertainty

The efficiency of the automatic execution of complex assembly tasks can be enhanced by the identification of the contact state. In this paper we derive a new method for testing a hypothesized contact state using force sensing in the presence of sensing and control uncertainty. The hypothesized contact state is represented as a collection of elementary contacts. The feasibility of the elementary contacts is tested by solving a linear program. No knowledge of the contact pressure distribution or of the contact forces is required, so our method can be used even when the contact forces are statically indeterminate. We give a geometric interpretation of the contact identification problem using the theory of polyhedral convex cones. If more than one contact state is feasible, we use the geometric interpretation to determine the likelihood of each feasible contact formation.