Position Control Of Three Degree Of Freedom Pneumatic Rectangular Compound Motion Platform

In this paper,the positioning control of the three degree of freedom pneumatic rectangular composite motion platform is studied.Because of the air compressibility,the friction of the rodless cylinder and the external disturbances,the control accuracy of the experimental platform is difficult and challenging.In this paper,the nonlinear control strategy is used to deal with the nonlinear factors in the system,in order to improve both the control accuracy and response speed of the three degree of freedom pneumatic right angle composite motion platform.Firstly,the research background and the current situation of the pneumatic servo system are introduced,and the algorithms of active disturbance rejection control,prescribed performance control and finite time control are simply described.In this part,the mechanical structures and control circuits of the three degree of freedom pneumatic right angle composite motion platform are described.Moreover,the components,measurement and control software,main components and working principle of the three degree of freedom pneumatic right angle composite motion platform are also introduced.In addition,the control process of the three degree of freedom pneumatic straight angle composite motion platform are explained in detail.Secondly,the position control of three degree of freedom pneumatic right angle compound motion platform is studied.A TD is used to arrange a transition process for the single cylinder control of the three degree of freedom pneumatic rectangular compound motion platform,so as to obtain the tracking signal and differential signal of the desired signal.An ESO is used to estimate the total disturbances.At the same time,the solution space of the extended state observer is obtained by using a Lyapunov method,which provides theoretical guidance for parameters adjustment in engineering practice.According to the estimated states,the prescribed performance controller is designed,and the estimated disturbances are compensated in the controller.The validity of the prescribed performance controller is proved by using the Lyapunov method.Experimental results show that the proposed control strategy is effective for the motion platform.Thirdly,the separation of the adaptive active disturbance rejection controller and the adaptive ESO is studied in this section.By adding pressure sensors,an accurate model with unmatched disturbance is established.The state matrix is transformed reasonably,then the adaptive active disturbance rejection controller and the adaptive ESO designed in this part are jointly proved by using a Lyapunov method.Moreover,the popular bounded stability conditions are obtained.Compared with the references,the control strategy improves the control accuracy and response speed of the platform,and the experimental results show that the effectiveness of the control strategy is verified.Finally,a double closed-loop control strategy is established for the three degree of freedom pneumatic rectangular compound motion platform with pressure sensor.In the inner loop,the inner loop controller and the generalized ESO are designed to compensate and estimate the matched disturbances.Similarly,in the outer loop,the outer loop controller and the super spiral ESO are designed to compensate and estimate the unmatched disturbances.By using a Lyapunov method,it is proved that the proposed control strategy can achieve finite time stability.The experimental results show that the proposed control strategy can effectively compensate system matching and unmatched disturbances,and the proposed control strategy improves the control effect of the platform compared with the reference.