Research On Contour Motion Control Of Two-dimensional Linear Drive Precision Aerostage

With the increasing development of industrial precision automation,the past “rotary motor + ball screw” transmission mode has been unable to meet the high-speed and high-precision technical requirements of precision automation.The combination of linear motor drive and air-bearing guide rail has become the mainstream mode of precision automation processing.Due to the increasingly complex machining contour trajectory of components and the continuous improvement of technical requirements,it is of great significance to study the contour motion control method of linear motor aerostage.In this thesis,the two-dimensional gantry linear motor aerostage is taken as the research object.Referring to the high-speed and large-stroke motion occasions,the main error sources of the contour trajectory of the two-dimensional aerostage are analyzed,and the suppression and compensation are carried out.The research is carried out from the aspects of linear motor servo control system,control loop stability analysis,single-axis linear motor control method and multi-axis contour motion control method.The contour control performance and system dynamic characteristics of the two-dimensional aerostage are analyzed through simulation and experimental methods.The main research contents are as follows :The trajectory comprehensive error sources of the two-dimensional linear aerostage are summarized.Based on the hardware system of the two-dimensional aerostage,the three-closed-loop control model is established.With the phase margin and amplitude margin as the judgment basis of the stability margin,the stability design of the position loop,velocity loop and current loop is carried out in Matlab / Simulink software.Two improved PID control methods for single axis motion control are proposed.Aiming at the problem that the conventional PID control can not meet the high positioning accuracy,the feedforward control idea is introduced to analyze the influence of the feedforward control parameters of speed and acceleration on the position tracking error.The fuzzy control rules are established according to the influence law and the experience of relevant experts,and compared with the conventional PID.Then,an improved PID control method based on iterative learning algorithm is proposed,and the comprehensive performance is compared and analyzed with the former.The anti-interference ability of the two methods is tested,and the optimization is used as the basis of the contour control system.In order to solve the problem of parameter mismatch between the axes of contour error,the variable gain cross coupling control method is added.The arc trajectory is used as the input signal,and the different curvature radius and motion speed are used as independent variables to analyze the coupling relationship between contour error and tracking error.Considering the time-varying arc trajectory,aiming at the problems of long time-consuming parameter setting and easy to be affected by the sudden change of contour error in the contour controller,based on the method with better comprehensive performance in Chapter 3,the fuzzy control algorithm with strong anti-interference is introduced in the design of the contour controller,and an improved chicken swarm optimization algorithm is proposed to find the best set of quantitative factors and proportional factors,so as to improve the parameter setting efficiency and contour trajectory accuracy.An experimental platform for contour trajectory accuracy measurement is built,and the communication test between the hardware system of the Ballbar instrument and the data acquisition software is carried out.The motion instructions are written in the motion control card,and the translated algorithm program code is input into the motion control card.Then,the effectiveness of the contour motion control method proposed in Chapter 4 is verified by the control variable method.