Research On Multifingered Dexterous Hand Driven By Ultrasonic Motors And Its Master-slave Control System

In order to meet the increasingly complex requirement of flexible task and dexterous teleoperation,robot multi-fingered dexterous hand, which has similar structure with human, is always an importantresearch aspect of robot. Furthemore, due to the limitations of the development of artificial intelligencetheory, computer-controlled technology, sensors and other supporting technologies, it is too difficult tomake the dexterous hand completely autonomous work in unstructured environment. Therefore, theapplication of master-slave control technology to teleoperate dexterous hand has also been researched.This thesis researches multi-fingered dexterous hand driven by ultrasonic motors (USMs) and itsmaster-slave control system.To conclude, main contributions of this dissertation are as follows.1. On the basis of analyzing existing robot dexterous hands and physiological structure of humanhand, a humanoid multi-fingered dexterous hand driven by ultrasonic motors is designed which is closeto human hand in the aspects of size, weight and degree of freedom.2. The robot D-H parameter method is applied to build kinematics model of the dexterous hand. Byreferring to the joint quadratic coupling relation of human finger, a kind of fast inverse kinematicsalgorithm, which consists of analytical and numerical methods, is proposed to solve the redundancyproblem of single finger, and the simulation is conducted. Considering the joints motion couplingproblem brought of the tendon transmission mode, mapping equations between joint space and drivingspace is established to realize motion control of dexterous finger.3. Multifingered grasping model under the teaching mode is built. The concept of contact safetymargin is proposed according to the experience of human grasping, and the nonlinear optimizationmodel of internal force with contact safety margin is also built by modifying constraint condition offriction cone, and the corresponding contact force is also obtained. In order to improve the graspingperformance, by taking object pose parameters as variables, the multi-objective optimization model ofgrasping is built based on the performance indices including position-grade and relative loadingcapability in joint space of robot hand. Then, a three-fingered robot hand grasping object is calculatedand analyzed, and multi-objective particle swarm optimization algorithm is applied to plan the objectpose while a set of non-dominated solutions is also obtained. The results demonstrate the proposedmethod can efficiently improve grasping performance under the condition of safe grasping.4. Two different types of master hand: wearable passive force feedback master hand and desktopactive force feedback master hand are developed, and the former one is conducted on the kinematics and dynamics optimization design. Then, the control system including hardware and software is establishedbased on DSP host controller. Moreover, the PID+Bang-Bang technology is applied to achievetrajectory tracking control in joint space and Cartesian space, and the fingertip contact force control isimplemented based on impedance control strategy, and frequency response test is also carried out. Inorder to measure the performance of the two developed master hands, experiments about master-slavecontrol and force feedback are respectively conducted.5. The performance and stability of bilateral teleoperation system are easily degraded by time delayand uncertainty factors. In order to solve this problem, a new control structure is proposed concerningdifferent task characteristics of master and slave sides. Because the master-side is vulnerable todisturbance in the realization of force feedback, a kind of nonlinear disturbance observer is designed foronline estimate and compensation. At the slave-side, impedance control based on sliding mode isapplied to ensure precise position tracking and desired interacting with the environment. The Liewellynabsolute stability criterion is adopted to derive stability condition and parameter selection criteria undera time delay. Finally, the proposed method is validated by experiments with a single-DOF teleoperationplatform, and the results show that the proposed method can improve operational performance whilehaving good robustness.