A Kinematics Control Scheme of Redundant Manipulators under Unknown Loads or External Forces

A kinematics control scheme in acceleration level is proposed to address the trajectory planning problem of redundant space manipulators under unknown loads or external forces. To achieve optimization of the joint torque from multiple sources, which is nonconvex relative to joint angles, quadratic programming (QP) is reconstructed through a novel multilevel simultaneous minimization scheme. This scheme, together with joint velocity norm minimization and physical limits avoidance formulated as the objective function and bound constraint into the QP problem. Subsequently, an extended recurrent neural network and intelligent numerical method, which are proven to converge, are established to solve the problem. Two trajectory tracking path simulations and experiments demonstrate the superb performance of this scheme when the manipulator is subjected to external forces or operating unknown loads. Comparisons with other schemes show that the proposed scheme is safer and more applicable.