Research On Pre-sliding Friction Suppression Method Of Precision Direct-drive Stage Based On Compliant Structure

With the rapid development of aerospace,micico-electronics,and precision manufacturing fields,there is creating requirements for improvement in machining workpiece accuracy.Therefore,the stage becomes a most important component in the machining system,and its motion accuracy directly affects the machining accuracy of the workp iece.In the high-precision stage system,friction disturbance becomes the most important factor affecting the machining accuracy of the workpiece,especially the pre-sliding friction will cause the quadrant glitches of the stage at the r everse motion,resulting in serious damage to the machining accuracy.So,how to reduce the influence of pre-sliding friction on the tracking performance has become a hot point in the precision machining fields.This thesis studies on this practical problem,through theoretical analysis,it reveals that the pre-sliding friction has nonlinear characteristics and hysteresis characteristics.On this basis,a new scheme for reducing the reversal error of the stage is proposed:by adding a low-rigidity compliant structure between the worktop and the guide rail slider,combined with the feedforward compensation based on the friction model.The control algorithm realizes the accurate filtering and compensation of the pre-sliding friction disturbance,thereby achieving the purpose of greatly improving the tracking accuracy of the stage at the reversal.According to the idea of low-rigid mechanical filtering,the task of structural design,equipment selection,assembly and debugging of the stage is completed,which lays a foundation for the subsequent friction compensation experiment.The Dahl friction parameter identification experiment was carried out by using the precision direct-drive stage designed in this thesis.According to the experimentally measured friction curve,the parameter identification results were obtained by least squares fitting.Subsequently,the PID control algorithm with Dahl friction model feedforward compensation is built based on Simulink,and the control algorithm is imported into the dSPACE real-time simulation system to realize the control effect of the stage.Finally,through multiple sets of sinusoidal displacement comparison experiments,it is proved that the experimental scheme proposed in this thesis can suppress the pre-sliding friction very well,greatly reducing the tracking error of the stage at the reversal,and thus improving the motion accuracy of the stage.