Trajectory Tracking Control Of A Rod Cylinder Servo System

The rod cylinder servo system is the most basic system of pneumatic technology applied in all walks of life.However,the nonlinear disturbances such as variable load,friction,imprecise model parameters,as well as the actual problems such as input saturation and input dead zone of flow proportional valves seriously affect the tracking control performance of the pneumatic system.Therefore,this paper takes the rod cylinder servo system as the research object to propose effective control strategies to improve the tracking performance and control accuracy of the system.First of all,the background and significance of the research topic,as well as the current research status of track tracking control of pneumatic rod cylinder servo system are shown.The structure,working principle and control difficulties of pneumatic rod cylinder servo system platform are introduced.The research ideas of this paper are are described systematically.Secondly,in order to solve the problems of friction and variable load in the pneumatic rod cylinder servo system,the super-twisting algorithm is applied to the design process of the extended state observer.The super-twisting extended state observer is designed to accurately estimate the unknown nonlinear disturbance caused by friction and variable load in finite time,and a finite-time controller is constructed to realize finite time tracking control of the pneumatic rod cylinder servo system based on the power integrator technique.Thirdly,in order to deal with the problem of friction model parameters' inaccuracy and flow proportional valves' input saturation,a time-varying gain extended state observer is designed to estimate the nonlinear disturbance caused by inaccuracy of measurement parameters.An auxiliary dynamic system is constructed based on the control input errors and tracking errors.The auxiliary dynamic system states are used in the design of a saturation controller to solve the problem of input saturation.Through the tracking test experiments,the results show that the anti-saturation control strategy is able to solve the problem of inaccurate measurement parameters and input saturation.Finally,in order to solve the nonlinear disturbance caused by air compressibility and friction,to solve input dead zone of flow proportional valves,and to verify the practicability of the adaptive algorithm in the actual pneumatic system,assume that the upper bound function of system nonlinear disturbance caused by friction and input dead zone is existent.An estimation function is designed to estimate the estimation parameters constructed by coefficients of the upper bound function,and the obtained estimation value is used in the controller design to compensate the system nonlinear disturbance,and the problem of control dead zone is solved.