Research On Adaptive Robust Control For Linear Motor With Output Constraints

In recent years,linear motor has been widely used in military,industrial,civil and other related fields,because of its unique mechanical structure and high speed,high precision and other advantages.However,linear motors are vulnerable to intermal uncertainties and external disturbances,resulting in poor control performance.What has become a hot research topic is how to design effective controller to deal with such bad effects and improve control performance.In this thesis,the Y-axis of the gantry linear motor machine tool is taken as the research plant.And the adaptive robust control of the output constraints of the linear motor is studied.According to the actual situation of gantry linear motor control system,a suitable mathematical model is established.The prior knowledge of the model is determined by parameter identification.Based on the adaptive robust control algorithma,a control law for linear motor with output constraints is designed.Considering that partial state of the system may not be available,then only the output of the system is used to design the adaptive robust control law under output constraints.Finally,an experimental platform for closed-loop control system of linear motor is built to verify the effectiveness of the two control laws.The results of this study are as follows:(1)Based on the adaptive robust control algorithm,barrier control Lyapunov function is selected to synthesize a control law for linear motor system with output constraints.Compared with the traditional quadratic control Lyapunov function,this control law can ensure that the tracking error of the system is always within a given range throughout the whole control process.The robust terms and adaptive terms in the control law can ensure that the control system has good transient and steady-state performance.The simulation and experimental results show that the proposed control law can guarantee the output constraints,and has good transient performance and steady-state accuracy.(2)For the problem of output constraints,considering that partial states of the system are not available in some specific situations,an adaptive robust control algorithm of output feedback is designed.Different from most system models,the unknown system state in this model is coupled with parametric uncertain nonlinearly.When designing the control law,an appropriate observer is constructed firstly.Then the total Lyapunov function of observer,control law and adaptive law is established.Based on the adaptive robust control design,the control law and adaptive law can be determined.Finally,the parts of the controller that cannot be cancelled or attenuated are restrained by the observer parameters which can be determined by the method of linear matrix inequality(LMI).The states of the whole control system are ensured uniformly ultimately bounded.The simulation and experimental results show that the control law can utilize the system output to fulfill the output constraints of the linear motor,and the closed-loop motor control system has satisfying transient performance and steady-state accuracy.There are 36 figures,9 tables and 61 references in this thesis.