Trajectory Planning of 7-DOF Humanoid Redundant Manipulator Based on Time Optimization

Because of redundant degrees of freedom and elbow offset, inverse kinematics (IK) of 7-DOF redundant manipulator is difficult to solve, which brings challenges to trajectory planning. In order to meet the planning requirements in different scenarios, an analytical IK algorithm and a time optimal trajectory planning algorithm are proposed. Specifically, the included angle (arm angle) between the plane of the shoulder, elbow and wrist of the manipulator and the reference plane is parameterized to represent all possible IK solutions within the specified arm angle range. Based on S velocity curve planning, joint angle is interpolated in joint space, and arm angle, end position and attitude are interpolated uniformly in Cartesian space to determine the unique IK solution. Simulation experiments verify the feasibility of the algorithm, and show good motion performance based on the actual manipulator platform.