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Abstract

The invention controls an under-actuated robot manipulator by first obtaining predetermined active joint accelerations of the active joints and the passive joint friction forces of the passive joints, then computing articulated body quantities for each of the joints from the current positions of the links, and finally computing from the articulated body quantities and from the active joint accelerations and the passive joint forces, active joint forces of the active joints. Ultimately, the invention transmits servo commands corresponding to the active joint forces thus computed to respective ones of the joint servos. The computation of the active joint forces is accomplished using a recursive dynamics algorithm. In this computation, an inward recursion is first carried out for each link beginning with the outermost link in order to compute the residual link force of each link from the active joint acceleration if the corresponding joint is active or from the known passive joint force if the corresponding joint is passive. Then, an outward recursion is carried out for each link beginning with the innermost link in which the active joint force is computed from the residual force if the corresponding joint is active or the passive joint acceleration is computed from the residual link force if the corresponding joint is passive.

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First Claim