Robust Synchronization Control Of Direct Drive H-type Motion Platform

H-type motion platform adopts the structure of bilateral drive by permanent magnet linear synchronous motor（PMLSM）,which has the advantages of simple mechanical structure,high stability,high speed and high precision,so it is widely used in precision machining and other fields.However,due to the mechanical coupling between the two parallel linear motors,motor parameter changes and external disturbance and other uncertain factors,the motion of the two parallel linear motors will not be synchronized,thus affecting the control accuracy and robustness of the system.For this reason,this thesis mainly focuses on the dynamics modeling and synchronous control of H-type motion platform,and adopts a variety of robust control strategies to control,in order to obtain high precision control performance and improve the robustness of the system.Firstly,the development status of direct drive technology and H-type motion platform at home and abroad is fully understood,as well as the main influencing factors of H-type motion platform and the related synchronous control strategy.Based on the Euler-Lagrange equation,a biaxial coupling dynamic model of H-type motion platform was established by considering the influence of torsional pendulum force and mechanical coupling caused by the movement of beam motor and the change of load.Then the state space expression of MIMO coupling system is obtained.The two-axis coupling model connects the two motors together,and the coupling factor is not treated as external disturbance like the traditional single-axis control,but considered from the whole model,which can effectively improve the precision of synchronous control.Secondly,based on the coupling dynamics model of H-type motion platform,the hybrid error was formed by combining the single-axis tracking error with the biaxial synchronization error and its change rate through the cross-coupling synchronous control structure,and the LQ optimal synchronous controller was designed by considering the new performance index of the hybrid error.The simulation results show that compared with the traditional PID control with independent axis,not only the synchronization control precision of the system is improved effectively,but also the tracking control precision of single axis is further improved.Finally,when the system is disturbed,using LQ optimal synchronous controller will degrade the robustness and control precision of the system.Aiming at this problem,and in order to further improve the control accuracy of the system,based on the coupling dynamics model of H-type motion platform and the cross-coupling synchronous control structure,the H_∞robust synchronous controller and the L₂ gain robust synchronous controller were designed respectively.In order to verify the effectiveness of the two robust synchronous controllers,the simulation is carried out under the condition of no disturbance load and different disturbance load.The simulation results show that,compared with the LQ optimal synchronous control method,the two robust synchronous control methods not only further improve the control accuracy of the system,but also make the system have better dynamic response characteristics and stronger robustness.Compared with the H_∞robust synchronous controller,the system withL₂ gain robust synchronous controller has smaller error fluctuation range after disturbance,faster recovery speed and stronger interference suppression ability,and its control accuracy and response speed are improved.