Robust Sliding Mode Tracking Control For Micro-hand System With Hysteresis

With the development of science and technology,soft robot has become an important part in the field of robot research.Micro-hand,as a soft robot that can achieve bidirectional bending by pneumatic drive,has a huge application prospect.However,due to the nonlinear characteristics of hysteresis in the operation of Micro-hand actuator,the stability and accuracy of the system are seriously affected.How to model and control hysteresis has become a hot topic in the research of Micro-hand actuator.Therefore,the robust stability and tracking control of hysteretic Micro-hand system based on the operator theory is studied in this paper,which mainly includes:(1)Nonlinear modeling of hysteretic Micro-hand system.Since the tensile and deformation of rubber tube will produce hysteresis,and affect the stability of the system and accurate grasping.Therefore,how to model the hysteresis needs to be solved.In this paper,based on the operator theory and the study of the input-output characteristics of Micro-hand system,the hysteretic nonlinear model of Micro-hand system based on Prandtl-Ishlinskii model is established.(2)Robust control scheme of compensating hysteresis nonlinearity.At first,by designing the compensation operator and observer,a control scheme based on the observer and the compensation operator is proposed to eliminate the influence of hysteresis nonlinearity on the system and ensure the stability of the system.Then,the robust passivity problem of uncertain nonlinear systems is studied,that is,a robust passivity-based control scheme based on isomorphism is proposed,and the inverse of hysteresis model is designed into an isomorphic compensator to satisfy both Bezout identity and passivity conditions,thus the robust stability and passivity of the system are ensured.(3)Non-singular terminal sliding mode tracking control scheme of hysteretic Micro-hand system.The non-singular terminal sliding mode tracking control scheme is proposed based on the robust right coprime factorization method,which guarantees the tracking performance of the system.In order to realize the precise grasp of Micro-hand system,the tracking control of Micro-hand system based on the integral sliding mode control method and terminal sliding mode control method is studied.The tracking design based on sliding mode surface and the control law can effectively eliminate static errors,improve the convergence rate the tracking performance,which is helpful for accurate grasping by using the Micro-hand in the future.(4)Robust passivity-based control scheme for Hamiltonian system.The operator theory and robust passivity control are extended.By analyzing the Hamiltonian system and combining the operator theory and passivity control method,the robust passivity control scheme of the Hamiltonian system is proposed,and the robust stability and passivity of the Hamiltonian system are achieved.