A Fast Stochastic Contact Model for Planar Pushing and Grasping: Theory and Experimental Validation

Authors: Jiaji Zhou, James Bagnell, Matthew Mason

Based on the convex force-motion polynomial model for quasi-static sliding \cite{Zhou16}, wederive the kinematic contact model for determining contact modes and instantaneousobject motion on a supporting surface given a position controlledmanipulator. The inherent stochasticity in object-to-surface frictiondistribution and object-to-manipulator coefficient offriction are modeled by sampling physically consistent parameters from appropriatedistributions. Thanks to the high fidelity and smoothness of convexpolynomial models, the mechanics of patch contact is captured whilebeing computationally efficient without mode selection at support points. The motion equations for both single and multiple frictionalcontacts are given. Simulation based on the model is validated with robotic pushingand grasping experiments.