Modeling of Frictional Contacts for Dynamic Simulation

The paper addresses rigid body dynamic simulation of mechanical systems with frictional contacts. It is well known that the use of Coulomb's law of friction with the principles of classical rigid body dynamics introduces mathematical inconsistencies. Speciically, the initial value problem may have no solutions or more than one solution. We show that a suitable lumped model of compliance in the normal and tangential directions can be used to establish uniqueness and existence. We also show how this model can be used for rigid body dynamic simulation. The second contribution of the paper is a rigid body impact model that can be used for simulating impacts with multiple concurrent frictional contacts. We show that the same compliant contact model, when used in small time intervals, yields solutions for the normal and tangential impulses that occur during impacts. We describe preliminary experimental results that show agreement with the predictions of the model for a class of frictional impacts.