Mechanical computation for passive force control

It is shown that a passive robotic wrist, of fixed mechanical design, can be programmed to execute a wide range of force control laws useful in automated assembly. A systematic characterization of the range of control laws (given by accommodation matrices) implementable by passive programmable hydraulic devices carried out. The authors use electrical network theory results to identify the accommodation matrices that are available in the joint-space of the wrist. These matrices are projected onto the task-space, and the range of task-space matrices is compared with a known class of matrices in an attempt to quantify the usefulness of passive devices. For simplicity, hydraulic networks consisting of tunable dampers are considered. It is shown that a broad range of accommodation matrices may be synthesized by passive devices with programmable parameters