Reducing the effects of shocks using redundant actuation

Robotic systems whose kinematic structure varies during their task are discussed. When the system´s kinematic structure changes large discontinuities may occur in the solution to its inverse dynamics problem. These discontinuities can be traced to discontinuous changes in the coefficients of the dynamics equations which describe the system´s behavior. When this change occurs on the left-hand side of the equations, it corresponds to a change in the kinematic structure of the system. When the change occurs on the right-hand side, it corresponds to a collision between two constituent objects in the system. Since these systems are redundantly actuated, the solution to their inverse dynamics problem may be chosen according to an optimality criterion. Two methods are presented to specify the optimization problem to reduce the effect of the discontinuities-one introduces rate-dependent terms in the objective function while the other positively limits the rate of change of the solution