Dynamics, Friction, and Complementarity Problems 2 D.E. Stewart J.C. Trinkle International Conference on Complementarity Problems, Johns Hopkins University, Baltimore, Nov. 1995 1995 JHU http://www.cs.tamu.edu/research/robotics/Trink/Papers/iccp95StewTrink.ps An overview is presented here of recent work and approaches to solving dynamic problems in rigid body mechanics with friction. It begins with the differential inclusion approach to Coulomb friction where the normal contact force is known. Numerical methods for these differential inclusions commonly lead to linear and nonlinear complementarity problems. Then the measure differential inclusion formulation of rigid body dynamics due to Moreau and others is presented. A novel algorithm for time-stepping for rigid body dynamics is given which avoids the "nonexistence" issues that arise in many other formulations. The time-stepping algorithm requires the solution of a nonlinear complementarity problem at each step. Results on the convergence of the numerical solutions to solutions in the sense of measure differential inclusions are given, and numerical results for an implementation of the method are shown.