Parameter identification of unknown load handled by space manipulator based on tactile and VEMS

The position and orientation of space manipulator and spacecraft will change when space manipulator captures unknown load, which is because their characteristic of dynamics and kinematics changes which are caused by unknown inertia parameter. When position and orientation change, the precise control of position and orientation for spacecraft is necessary. The precise control strategy is based on the accurate parameters identification of unknown load. In order to accurate identify load parameter online, a method which uses the information of VEMS (Virtual- End-Moment-Sensor) and tactile sensor of end-effector to identify the inertial parameters of unknown load is proposed in this paper. The method is based on Newton - Euler equations and uses NLMS (Normalized Least Mean Square) adaptive filtering. The software MATLAB/Simulink and ADAMS are used to build the unknown load parameter identification simulation platform in order to verify the algorithm. The executive mechanism of simulation platform includes a multi-DOF (Degrees of Freedom) space manipulator and an end-effector with two claws. The manipulator arm joints have torque sensors, which are used to calculate the datas of VEMS. Each inner side of the claw of the end-effector has a tactile sensor, whose data are used to obtain inertia parameter. The simulation shows that the identification results are stable (identification error are less 0.02%), and the proposed identification method is effective.