Research On Control Technology Of Tendon-driven Space Multi-finger Dexterous Hand

With the rapid development of space technology, the need of the robot with ability of dexterous manipulation to replace astronaut for extravehicular activities(EVA) has been more urgent. To meet the requirements, the key issues related to the manipulation and control of tendon-driven multi-fingered dexterous hand for on-orbit-servicing are studied in this paper.Firstly, the structure of the dexterous hand is introduced, the linearization of the joint-tendon coupling is given in order to solve the inverse kinematics, while gives the tendon-joint structure matrix for the tendon-joint structure. Multiple sensors is the key to achieve compliant force control, the six-dimensional force sensor, hall position sensor, and tendon tension sensor used in the hand are also introduced. Using kinematics theory D-H parameter method, the index finger forward kinematics equation and the inverse kinematics are given. Then the Jacobi matrix and dynamic model for the finger are deduced in this paper. Considering the feature of tendon-driven finger, a tendon tension distribution algorithm(TDA) is given. On the basis of TDA, an impedance control compensator to control the fingertip contact force is proposed. In order to improve the ability to adapt to the external environment, the adaptive control module is added. Using the MATLAB and ADAMS co-simulation system to verify the control systems aforementioned, the simulation results have shown that the adaptive impedance control system for a single finger is able to impose desire contact force to target objects which have different stiffness and still be valid when target object position is uncertainty. Finally, in order to control multi-finger in precision grasp model to grasp a cylindrical object, introduces the grasp point planning and force-closure grasp optimal calculation, and the simulation results shows that the fingertip contact force tracking well; at the same time in the power grasp model, combines position control and joint space torque impedance control means to achieve wrapping object and threshold limit for joint torques.