Robust Tracking Control For Micro-hand With Hysteresis

In recent years,robot technology has made great contributions in different industries and fields.It is considered to be one of the high technologies of great significance for the development of emerging industries in the future.Compared with the popular "rigid body robot" in previous researches,soft robot has attracted more and more researchers’ attention due to its advantages such as high degree of freedom,convenient design,simple overall structure and strong spatial adaptability.In particular,it has made outstanding contributions to medical treatment,geological survey and underwater exploration.Among the many researches on soft robot,the research on micro-hand system is an indispensable branch.Micro-hand system is also called soft actuator,it is a kind of flexible actuator that can be bent to both sides.In today’s industrial manufacturing,these soft actuators are mostly made of silicone rubber materials,so they can be adapted to a variety of operating environments,and can be safe for both the operator and the object.However,hysteresis properties are common in soft materials such as silicone rubber,which can cause the actuator to fail to achieve the desired goal during the task.Therefore,considering the influence of hysteresis is an indispensable part in the design of software actuator.The model obtained by combining the Prandtl-Ishlinskii hysteresis model with the operator-based robust right coprime factorization method can help researchers analyze and control the micro-hand system with hysteresis.Therefore,this paper focuses on:First,this paper takes the micro-hand system with hysteresis as the research object,combines the dynamic model of the micro-hand system with the Prandtl-Ishlinskii hysteresis model,obtains a new model,and uses the operator theory to carry out the robust right mutual prime factorization of the obtained model.This factorization is very necessary,because the system obtained after factorization,only the relation between input and output needs to be considered,that is,the relation between the inflation pressure and the bending angle of the micro-hand.At the same time,the complex hysteresis behavior is divided into two parts: one is reversible part,and the other is disturbed part,so as to facilitate the robust and stable tracking control of the micro-hand system with hysteresis.Secondly,a system can be realized only if it has stability.Based on this,the robust stability of the micro-hand system with hysteresis is considered.Different from the robust stability condition of Bezout identity based on the operator theory,a new robust stability condition is proposed in this paper.When the model of the micro-hand system with hysteresis satisfies this condition,its robust stability can be guaranteed.Thirdly,uncertainty and hysteresis exist in the micro-hand system,which will cause interference to the grasping function of the micro-hand system and lead to the failure of the work.Therefore,the tracking problem of micro-hand system with hysteresis needs to be solved.In this paper,a robust tracking control method based on internal model control is proposed.Combined with the theory of the operator and the robust right coprime factorization,a specific internal model tracking controller is designed to meet the tracking conditions and ensure the good tracking performance of the system.Finally,for each design link,the corresponding numerical simulations are carried out,to verify the feasibility and effectiveness of the proposed scheme.By comparing and analyzing the simulation results,it can be found that the robustness and tracking of the micro-hand system with hysteresis can meet the expectations by the designed robust tracking controller.