Research On FTS Sliding Mode Repetitive Control Of Voice Coil Motor

The optical technology,with the continuous development of science and technology and the continuous improvement of living standards,has played a key role in the development of the fields such military,aerospace science and technology,medical science,communication engineering,etc.Accordingly,it has become critical to study the methods of realizing the fine machining on the optical curved components with low cost has also become the key research.Among them,the Fast Tool Servo(FTS),characterized by high frequency response,high precision,large stroke,high stiffness,etc.,adopts diamond as cutting tools,and is one of the processing technologies under extensive research at present.In this paper,the voice coil motor is taken as the controlled object to study the control methods of FTS system in improving the tracking precision and suppress disturbance in the course processing.The specific research contents are as follows:Firstly,extensive domestic and foreign references are collected and consulted,so as to master the control algorithm related to the voice coil motor and Fast Tool Servo device,and applicable to the voice coil motor FTS.Therefrom,the mathematical model of the system is established regarding the basic structure and the working principle of the system that the voice coil motor drives Fast Tool Servo device and the core performance index of FTS device.Secondly,for the tracking problem of periodic disturbance and periodic input signal of voice coil motor FTS servo system,an improved repetitive compensation PI control is proposed,which can not only track the periodic signal accurately,suppress the periodic disturbance,but also solve the problem of poor dynamic response caused by the delay of repetitive controller.A super helix observer is constructed to suppress the aperiodic disturbance,and the speed required by the super helix observer is estimated by the robust precise differentiator.Combining the advantages of the two control methods,an improved repetitive control based on the super helix observer is proposed,which is simulated in MATLAB/Simulink,and the comparative study indicates the superiority of the algorithm.Finally,in the practice,there are some external disturbances and other uncertainties related to Fast Tool Servo device,which will greatly reduce the tracking accuracy.On this basis a super-spiral sliding mode control based on disturbance observer is proposed.Thedisturbance observer can estimate external disturbance and other uncertainties,and the disturbance bound estimated by the disturbance observer is equivalent to the control input,which is equal to a disturbance signal compensating to the output of the controller to counteract the actual disturbance.On the principle of sliding mode control,the control law is designed through the super helix algorithm.Combining the disturbance estimation from the disturbance observer with the super helix control law,the machining accuracy and anti-interference ability of the components can be effectively improved.Based on the theoretical analysis,the algorithm is simulated through MATLAB/Simulink to verify the effectiveness of the control algorithm.Compared with the super helix sliding mode control,it can be clearly seen that the super helix sliding mode control based on the disturbance observer has stronger anti-interference.