A general and systematic method to find the dynamic parameters, known as the base parameters, that directly contribute to joint torques for both open and closed kinematic chains is presented. The principal base parameters are defined as a set of the base parameters with their order of sensitivity. The principal base parameters are obtained by taking into account the nonlinearity. It is also shown that for a closed kinematic chain a set of base parameters are invariant to the location and the number of the actuated joints if they can sufficiently activate the mechanism.>

The authors discuss a general and systematic computational scheme of the inverse dynamics of closed-link mechanisms. It is derived by using d'Alembert's principle and obtained without computing the Lagrange Multipliers. To account for the constraints, only the Jacobian matrix of the passive joint angles in terms of actuated ones is required. Given a nonredundant actuator system, this allows a unique representation of the constraints even for complicated multiloop closed-link mechanisms. The inverse dynamics of closed-link mechanisms that contain redundant actuators and their redundancy optimization are also discussed. For a redundant actuation system that contains N/sub r/ redundant actuators, the passive joint angles are represented by N/sub r/+1 independent ways as functions of actuated joints. Using their Jacobian matrices, the actuation redundancy of a closed-link mechanism is parameterized by an N/sub r/-dimensional arbitrary vector in a linear equation. Numerical examples are given to show the computational efficiency of inverse dynamics computation and the potential of closed-link manipulators with actuation redundancy.>

A general and systematic scheme for computing the dynamics of closed link mechanisms is derived using D'Alembert's principle. To account for the constraints, only the Jacobian matrix of the function which represents the passive joint angles in terms of the actuated ones is required. Given a nonredundant actuator system, this allows a unique representation of the constraints, even for a complicated multi-loop closed link mechanism. The scheme is computationally efficient because it is not necessary to compute Lagrange multipliers. A redundant actuator system is formulated, and the utilization of redundancy is actuation is illustrated.>