Adaptive Control For Pneumatic Motion Simulation Platform With Unknown Parameters And Disturbances

In this paper,a pneumatic motion simulation platform driven by pneumatic artificial muscles is taken as a research object,and trajectory tracking control of deflection motions is studied for the pneumatic motion simulation platform deflection motion.Difficulties and challenges on controling of the pneumatic motion simulation platform are brought by some uncertainty factors such as air compressibility,flexibility of pneumatic artificial muscle and load variation of the pneumatic motion simulation platform.Adaptive compensation control strategies are considered in this paper to deal with unknown parameters and total disturbances in the pneumatic motion simulation platform system,so as to improve control precision and response speed of the pneumatic motion simulation platform under different simulated motion.Firstly,research backgrounds of this paper and research status of control methods used in this paper are introduced.The mechanical structure,power circuit and control circuit of the pneumatic motion simulation platform are described.Components,application software,main pneumatic components and its working principle are introduced for the pneumatic motion simulation platform.A control process of the pneumatic motion simulation platform used in this paper is introduced in detail.Secondly,aiming at tracking control of the single-joint rotating system of the pneumatic motion simulation platform driven by pneumatic artificial muscles,a tracking differentiator is used to arrange a transition process to obtain a tracking signal and differential signal of a desired signal.An adaptive extended state observer is designed to estimate the unknown states and disturbances in the single-joint rotating system.And unknown parameters in the single-joint rotating system are estimated by adaptive laws.According to the estimated state and parameters,an adaptive backstepping controller is designed based on backstepping technology,and the estimated disturbance is compensated in the adaptive backstepping controller.Experimental results show that the designed control method can achieve high control precision and response speed under variable load and amplitude conditions for the pneumatic motion simulation platform.Thirdly,problem on dead zone of pneumatic artificial muscle is considered,dead zone pressure threshold is estimated and compensated by adaptive control method.In addition,a back-stepping extended state observer is designed by using the back-stepping technique,and a Lyapunov method is used to prove that the back-stepping extended state observer can achieve finite-time convergence.Experimental results show that the adaptive control based on the back-stepping extended state observer can improve the control precision and response speed of the single-joint rotating system for the pneumatic motion simulation platform driven by pneumatic artificial muscle.Finally,for angle attitude control of two-degree-of-freedom deflection motion for the pneumatic motion simulation platform,a Tornambe controller is used to deal with the coupling and unmodeled dynamics for the two-degree-of-freedom deflection deflection motion dynamic system.Tracking differentiators are used to process error signals of deflection motions,and the two-degree-of-freedom angle attitude control of the pneumatic motion simulation platform is realized under interference of white Gaussian noises.