Hewlett-Packard Company

M Shahid Mujtaba

William D Fisher

A hybrid position and force control system for a robotic manipulator. A displacement error signal of an end effector such as a robotic hand is multiplied by a pseudo-inverse of a matrix product of a selection matrix and a Jacobian matrix to provide a joint displacement error signal in the coordinates of the various joints of the manipulator. The system may be tuned for obstacle avoidance and the like by means of a joint tuning signal having displacement and force components each produced by multiplying a user-provided tuning signal by a matrix difference between an identity matrix and a matrix product of a pseudo-inverse of the Jacobian mattrix and the Jacobian matrix.

System for hybrid position and force control

A kinematic method to operate a multi-jointed robot to achieve coordinated, speed-invariant motion when the robot's end effector is moved along a predefined path. To accomplish such operation, a total execution time function is defined which is a function of acceleration time, slew time, and deceleration time for the joints. Values for the acceleration time, slew time, and deceleration time are calculated which minimize the total time function subject to constraints on the displacement, the limiting velocity, the limiting acceleration, and the limiting deceleration for the joints. Then, the end effector of the robot is operated such that all joints start moving at the same instant, all joints accelerate for the same period, all joints slew for the same period, and all joints decelerate for the same period. During such motion, at least one moving joint is responsible for determining the acceleration time, at least one other moving joint (or possibly the same joint) is responsible for determining the deceleration time, and at least one moving joint (or one of the two prior joints) is responsible for determining the slew time. Also during such motion, each moving joint will progress through its motion at the same relative rate; that is, at the time the ith joint completes some percentage of its travel distance, any other moving joint will complete the same percentage of its travel distance.

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Milpitas, CA, United States of America

M Shahid Mujtaba