Simulation of contact using a nonlinear damping model

In this paper, a simple nonlinear contact model is presented for use in computer simulation. The nonlinear model is shown to maintain the computational simplicity of the linear model while addressing many of its deficiencies. One such advantage is that contact forces vary continuously over time. A new phase plane solution for the nonlinear model is obtained which reveals many previously unnoted properties. These include proper variation of the coefficient of restitution with impact velocity over a wide range of impact velocities, independence of model parameters, and lack of tensile (sticking) forces in simple impacts. An example is presented which demonstrates the use of the contact model in simulating the foot-ground interaction during the locomotion cycle of a walking machine.