Control input reconstruction using redundancy under torque limit

Various physical limitations which intrinsically exist in the manipulator control system, for example kinematic limits and torque limit, cause some undesirable effects. Specifically, when one or more actuators are saturated in torque the expected control performance can not be achieved. The effect of torque limit, especially for redundant manipulators, is studied in this article, and a local and analytic method to reconstruct the control input using the redundancy is proposed based on the kinematically decoupled modeling of redundant manipulators. It results in exact compensation of the task motion dynamic error at the cost of the least null motion dynamic error. Numerical simulations help to verify the advantages of the proposed scheme