Robust Tracking Control Of Micro-hand System

In recent years,the research on soft robots has been attracting more and more attention with the development of medical technology and the arrival of aging society.It has good application prospects,especially in the fields of minimally invasive surgery,auxiliary rehabilitation systems.In the study of human arm movement,the research of soft actuators is also one of the important topics in the field of robotics.The actuator is usually made of silicone rubber material,which makes it have low mechanical resistance and high safety and high adaptability to fragile objects,in which Micro-hand,as the main body in the research of soft actuators,is a flexible actuator that can realize bidirectional bending.However,the inherent non-linearity of the soft materials and the soft actuator itself has brought great challenges to the dynamic modeling of the actuator and the design of the controller,so this kind of research is of very important significance.The robust right coprime factorization method based on the operator theory is unique in dealing with nonlinear characteristics and robust stability.Therefore,this paper focuses on:Firstly,in this paper,Micro-hand actuator(miniature soft actuator)is taken as the research object,and the mathematical modeling of Micro-hand system is carried out by using operator theory,only considering the relationship between the output(actuator bending angle)and the input(inflation pressure).Then,in view of the shortcomings of the constant rubber radius of the actuator in the existing literature,the recursive least squares identification algorithm was used to identify the rubber radius of the actuator,and the simulation verification was carried out.Secondly,energy conversion exists in all forms of nonlinear systems.Therefore,based on passive control method,robust control of micro-hand system is studied in this paper,that is,the passive control method and the robust right coprime factorization method are combined to design a robust passive controller to ensure the robust stability and passivity of the system.Thirdly,the uncertainty exists in the Micro-hand nonlinear system,and many situations require the actuator to grasp accurately,so the perfect tracking problem of the uncertain Micro-hand nonlinear system must be considered.In this paper,two robust tracking control methods are proposed: first,the robust tracking control method based on internal model,specifically based on the principle of internal model control,combined with the robust right coprime factorization method to design the robust controller and tracking compensation controller,so that the system can maintain stability and ensure that the output can better track the expected input.second,the robust tracking control method based on the integral sliding mode,due to the strong robustness of the integral sliding mode control itself,and the introduced integral term can better suppress the steady-state error.Therefore,the designed integral sliding mode tracking controller can better realize the tracking performance of the system.In order to verify the effectiveness of our proposed method,the simulation results of the proposed tracking control scheme are compared and analyzed.The simulation results show that the system has good robustness and passivity under the action of robust passive controller,but the tracking error is obviously large,and the range of tracking error is greatly reduced by using robust tracking control method based on internal mode.Combined with the integral sliding mode tracking control method using robust right coprime factorization,its tracking effect is better,so the integral sliding mode control method has better tracking performance for the Micro-hand nonlinear system and is less affected by error fluctuation.In general,the two proposed tracking robust control methods can achieve the tracking control.