Research On Cooperative Control Method Of Redundant Direct Drive Gantry System In Complex Environment

As the core component of a new generation of high-end manufacturing equipment,the redundant direct-drive gantry system has attracted much attention in the fields of semiconductor production,electronic assembly,digital printing,and biomedicine.Compared with single-axis motion,the coordinated control of gantry system is more complicated and important.The speed and precision of its movement directly determine the processing quality and production efficiency of high-end manufacturing equipment.With the complexity of application scenarios and the diversification of tasks,the realization of precise coordinated motion of direct-drive gantry platforms faces many challenges.On the one hand,there are complex coupling constraints in the mechanical structure of the gantry system,and the mutual interference between the movements of the axes also aggravates the difficulty of system control.In addition,various uncertainties and nonlinear disturbances such as thrust fluctuations,load changes,time delays,and measurement noises that inevitably exist in the system restrict the steady-state and transient performance of the motion system at all times.How to realize the high-performance cooperative control of the redundant direct-drive gantry system in a complex environment is an urgent scientific problem that needs to be solved,and it is of great significance to promote the development of key technologies for high-end manufacturing equipment.Therefore,based on the demand for high-speed and high-precision cooperative motion control in a complex environment,this thesis first analyzes and summarizes the related research on direct-drive gantry cooperative control at home and abroad.Then,the problems related to the collaborative control of redundant direct-drive gantry systems are studied from the shallower to the deeper,and improvements and innovations are made on the basis of existing methods in these fields.Based on the above analysis,the research of this thesis includes the following aspects:First,considering the rigid-flexible coupling characteristics of the moving parts comprehensively,the coupling relationship between the beam and the load in the feed and rotation directions is clarified.The force analysis and mathematical description of each motion axis are carried out respectively,and on this basis,the generalized force model under different motion dimensions is derived.The kinetic energy generated by the movement of the gantry system is obtained through the data information fed back by the optical encoder,and the equivalent potential energy generated by the flexible mode when the beam rotates is explored.Based on the Lagrangian equation,the coupled mathematical model expression of the redundant direct-drive gantry system is obtained.Based on the least squares identification principle,the prior knowledge of dynamic model parameters is obtained,which lays the foundation for further research on multi-axis cooperative motion control of redundant direct-drive gantry systems.Secondly,from the perspective of easy engineering implementation,the influence of the nonlinear dynamics of the system on the synchronization performance of the beam is focused on,and a high-precision master-slave synchronization tracking control method based on nonlinear dynamics compensation is proposed.Aiming at the problem of poor accuracy and stability in the traditional master-slave structure,an enhanced master-slave control structure is designed,and the goal of information closed-loop and real-time control is achieved based on the error coupling model.Aiming at the nonlinear thrust fluctuation existing in the direct drive motion mode,a parameter self-learning mechanism is designed to compensate the dynamic model.According to the obtained position,speed and other information,a feedback controller is designed to suppress unknown disturbances and improve the stability of the system.The comprehensively obtained controller output is calculated and distributed through the error coupling parameters to realize precise synchronous tracking motion.Comparative experiments are carried out on the actual physical platform to evaluate the effectiveness and performance advantages of the proposed control method.Then,with the control goal of linear feed and rotation internal force adjustment,the effects of various uncertainties and nonlinear disturbances in complex working conditions are studied,and a strong anti-disturbance synchronization control method based on neural network is designed.The active control is carried out according to the coupling mechanism model of the gantry beam subsystem,which overcomes the limitations of the system performance caused by ignoring the high-frequency rotation mode and its coupling effect in traditional modeling.An online learning mechanism is designed to realize the dynamic adjustment of parameters,and the expected model compensation technology is introduced to avoid the influence of measurement noise.Aiming at the system vibration caused by high-speed and high-thrust working conditions,a robust closed-loop control link is designed to reduce the influence of disturbance.According to the powerful nonlinear mapping ability of RBF neural network,the regression quantity residual and unknown strong interference are effectively compensated,so as to avoid system instability caused by excessive control gain.The stability of the closed-loop system is proved,and the simulation experiment is designed based on the direct drive gantry platform to verify the effectiveness of the proposed scheme.In addition,in order to meet the needs of actual industrial production tasks,the problem of unknown distribution of the center of mass of the beam and the decrease of synchronization accuracy caused by the load movement is studied,and a compound adaptive bilateral cooperative control method based on the position estimation of the center of mass is proposed.The motion form of the load is explored,and the connection between the load motion feedback and the position of the center of mass of the beam is established based on the geometric parameter information.In order to obtain the unknown parameters in the mathematical function,the Laplace transform is performed on the coupled dynamic model to obtain the transfer function between the input and output of the control system.The unknown parameter information is solved by frequency domain characteristic analysis and system identification method,and the estimated relationship between the load position and the center of mass of the beam is obtained.In order to further improve the robustness and cooperative motion accuracy of the closed-loop system,a composite adaptive control algorithm is designed to effectively suppress parameter perturbations and nonlinear disturbances.In order to reduce the influence of coupling interference,the real-time thrust distribution of the two axes is carried out according to the estimated relationship of the center of mass,and finally the high-precision synchronous control of the dual-drive gantry under the load motion is realized.Finally,based on the three-degree-of-freedom coupled dynamic model,the cooperative motion control problem under preset performance is studied,and a multi-axis cooperative control method with transient and steady-state performance guarantee is proposed.In order to ensure that the designed controller makes the final steady-state error and dynamic response within the preset performance envelope,the expected performance constraints are set for the state errors of each servo axis.In order to avoid complex mathematical calculations in the later controller design process,the design error conversion function simplifies the set constraint problem and derives the converted theoretical error model.Design a robust controller and model compensation mechanism to adapt to changes in system parameters,and use neural network control technology to compensate nonlinear disturbances to avoid system jitter in complex working conditions.Based on the Lasalle invariant set theorem,the asymptotic stability of the closed-loop system is proved.Two experimental scenarios with and without load were set up for experiments,and the proposed control algorithm was verified to meet the requirements of multi-axis cooperative control tasks.