求解SSRMS构型空间机械臂逆运动学的方法

The SSRMS-type manipulators are widely used in space on-orbit services, but the inverse kinematics is difficult to solve due to redundancy and the existence of shoulder, axis, and wrist offsets. Although the joint angle parameterization method can obtain the analytical solution of inverse kinematics, the success rate is highly dependent on the given value of the parameter. The method based on the Jacobian matrix will reduce the kinematics performance of the manipulator when considering singularity avoidance. To solve these issues, an inverse kinematics solution method (CCDJAP-IK) based on the combination of the cyclic coordinate descent method and the joint angle parameterization method is proposed. This method has the advantages of being insensitive to Jacobian matrix singularities, avoiding joint limits, and finding multiple exact solutions. The approximate solution obtained based on the cyclic coordinate descent method is used as the given value of the parameter in the joint angle parameterization method, which reduces the blindness in determining parameter value and increases the success rate of the solution. The movement of the end effector is converted into the movement of the endpoint of the sixth joint restricted only in the y-axis direction, which simplifies the objective function and the iterative steps of the algorithm, and improves the calculation efficiency. Taking the HIT-SSRMS manipulator as an example, simulation experiments are carried out. The results show that: under the condition that the current configuration and the desired pose are randomly selected in the workspace, the average calculation time and the success rate of the CCDJAP-IK method are 4.86 ms and 99.32%, respectively, which is an effective and reliable method for solving the inverse kinematics of SSRMS-type manipulator. When tracking the Cartesian path, the tracking accuracy, joint space continuity, and real-time performance of the CCDJAP-IK method meet the task requirements, so it can be applied to the real-time path tracking task of the manipulators.