The Research On Dynamics Model And Synchronous Control Technology Of Dual-driving Feed System

Feed system is the key control unit and actuator of CNC machine tools,which will directly affect its working performance.The dual-driving feed system which is synchronously drived by double servo motors in the same feed direction can achieve better rigidity,accuracy and higher acceleration.The dual-driving feed technology has been the important research direction of advanced CNC machine tools.However,the synchronization and tracking performance will be affected by the diversities of servo and mechanical characteristics,the nonlinear mechanical coupling,resonant modes,and nonlinearity frictions.The requirements of dual-driving synchronization control can not be satisfied by the traditional CNC system,which aimed to improve the bandwidth and the capacity of resisting disturbances.Therefore,this paper focus on the synchronous control technology of dual-driving system,do the theory and experimental researches on the dynamics model method,synchronous control strategy and algorithm,and the resonant suppressing.The main contents of this paper are as follows:(1)The hybrid parameters model of dual-driving system which driven by center of gravity has been built.The key parameters have been identified and calculated by identification experiment and theory calculation,and the natural frequency and mode of vabrition have been predicted.Moreover,the model has been effectively validated by the comparison between the results of modal experiment and the synchronous feed dynamic characteristics experiment and simulation.The influence of moving of center of gravity on pitch errors and torsion errors has been analyzed,which can be used as the basis of the research on the synchronous control.(2)The cross-coupled Terminal sliding mode control based on switching function gain fuzzy control has been provided based on the dynamics model.The chattering has been eliminated by the design of continuous saturation function and exponential reaching law.To solved the low robustness caused by the real-time decoupling and following process of dual axes which existing in cross-coupled control,the peak value has been detected by dual-driving feed experiment,and the switching function gain fuzzy control has been proposed to eliminate the synchronous error.And the stability of the controller has been proved by Lyapunov criteria.The co-simulation based on Matlab and ADAMS has been proposed,and the comparison of different synchronous control strategies and algorithms has been presented.(3)The control performance and bandwidth will be reduced by the mechanical resonant.In order to further improve the synchronization performance,the resonant suppression has been studied.Hence,the resonant mechanism of dual-driving system has been analyzed,and the differences of torque and angular velocity between dual axes of four inertia and four spring multi-freedom system have been detected.The frequency response has been obtained by FT.The double second order notch filter has been designed,and the parameters have been analyzed.Considering the differences of torque and angular velocity between dual axes and nonlinearity friction,the active damping method based on state feedback has been proposed.The effectiveness of proposed resonant suppression(RS)method has been validated by experiment.(4)The synchronous control experiment has been presented based on dual-driving feed system.Firstly,a two-dimensional dual-driving feed experiment platform has been established.The proposed cross-coupled FLTSMC+RS control method has been effectively validated by being compared with traditional cross-coupled PID and normal sliding mode control(NSMC).Secondly,the detection scheme of dual-driving linear displacement used dual-frequency laser interferometer has been provided.The experimental results show that,the sudden change of acceleration and reverse process are the key reason to lead to vibration of synchronous and tracking errors.The different constant velocities have no effect on the synchronous and tracking errors of linear displacement.Moreover,the linear displacement has a bigger role to affect synchronous and tracking errors than pitch and torsion angle.Finally,in order to ensure the torque balance of double-loads in the feed and clamp process,the synchronous control experiment has been proposed by double-loads press brake.The experimental results show the effective and capacity of resisting disturbance of proposed cross-coupled FLTSMC+RS method.