Gradient projection method of kinematically redundant manipulator based on improved scale factor

Abstract

This paper firstly introduces the research status of gradient projection method (GPM) of redundant manipulator, then presents a 7-DOF (degree of freedom) redundant manipulator composes of a 3-DOF shoulder joint, a 1-DOF elbow joint, and a 3-DOF wrist joint. Different from many other 7-DOF redundant manipulators, shoulder and wrist joints of the manipulator presented in paper are not spherical joints. The GPM is provided for inverse kinematics analysis. Scale factor is an important parameter in GPM, if the scale factor is utilized improperly, it can cause the GPM invalid or enable computational efficiency low. In this paper the improved scale factor is proposed in GPM. At last, the simulations of the GPM based on fixed scale factor, balanced scale factor and improved scale factor method are compared, the simulations demonstrated the improved scale factor method can overcome velocity impulses shortcoming of the fixed scale factor method, and rectify deficiency of the balanced scale factor method.