Research On Control Scheme For Multi-finger Hand Based On Cross Coupled Concept

The dexterous robot hand has become one of the most important research aspects in the robot field in order to improve intelligent and manipulative levels of the robot. According to the national nature science fund program"Research of the real-time force optimization and independent manipulating control of the multi-fingered robot hand"(No. 60675045), this dissertation studies the control scheme of the HIT/DLR multi-fingered hand based on cross-coupled strategy.The precise control of fingertip is the basis for achieving precise operation. Currently, the fingertip trajectory in Cartesian space is guaranteed by the joint position indirectly, which affect the performance of multi-fingered hand in operation because of not forming closed loop control. In this dissertation, after setting up the mathematical model of multi-fingered hand, a cross-coupled control algorithm in Cartesian space of a single-finger is constructed. Firstly the general form of joint coupled error is obtained according to finger kinematics and fingertip trajectory, then a feed forward controller and a slide mode controller are designed based on cross-coupled method, the stability of the controllers were proved or simulated. Experiments show that the controllers have higher accuracy and robustness.Combing multi-fingered kinematics and structural characteristics of dexterous hand, the position control and impedance control algorithm is studied to coordinate the movement of all fingers. A slide-mode controller including synchronization error of multi-fingers and trajectory error of single-fingered is employed based on finger grasping features. An impedance cross-coupled controller is designed through position correction vector, which is transformed from the joint torque sensor, to keep all fingers as an envelope shape and realize stable grasping. Faced the difficulty of tuning parameters and system vibration, a combination of fuzzy control and slide-mode control is set up to make the system more flexibility and stability profiting from parameter adjust online. Experiments demonstrated that this control scheme is effective.