On the use of iterative LCP solvers for dry frictional contacts in grasping

In this paper we propose the use of new iterative methods to solve symmetric linear complementarity problems (SLCP) that arise in the computation of dry frictional contacts in multi-rigid-body dynamics. Specifically, we explore the two-stage iterative algorithm developed by Morales, Nocedal and Smelyanskiy. The underlying idea of that method is to combine projected Gauss-Seidel iterations with subspace minimization steps. Gauss-Seidel iterations are aimed to obtain a high quality estimation of the active set. Subspace minimization steps focus on the accurate computation of the inactive components of the solution. Overall the new method is able to compute fast and accurate solutions of severely ill-conditioned LCPs. We compare the performance of a modification of the iterative method of Morales et al with Lemke´s algorithm on robotic object grasping problems.