Hybrid Vibration Isolation Research Of Grating Ruling Machine Based On Negative Stiffness Principle

The grating ruling machine with large area and high precision has the characteristics of complex structure,strict requirements for parts error distribution and nanometer accuracy.The influence of any external environmental disturbance may affect the positioning accuracy and machining accuracy of the grating ruling machine.To reduce the external environment vibration by adopting effective isolation scheme influence of the positioning accuracy and machining accuracy of grating ruling machine.This paper investigates the working environment of grating ruling machine and introduces the principle of negative stiffness to reduce the natural frequency of the vibration isolation platform of grating ruling machine.Finally,the random vibration of the grating ruling machine is analyzed by using the composite vibration isolation method.The main contents of this paper are as follows:(1)The working environment of the grating ruling machine is surveyed,and the source and frequency range of environmental vibration factors affecting the accuracy are analyzed.The main factors affecting the positioning error of the grating ruling machine are determined according to the variation of the positioning error of the grating ruling machine with the number of lines.Finally,pedestrian excitation and the transfer path of environment vibration are analyzed.(2)The stiffness displacement model of the rectangular permanent magnet is established based on the point magnetic charge model and the virtual work principle.The influence of magnet spacing and magnet shape on the nonlinear degree of magnetic gravity negative stiffness is analyzed.The nonlinearity of the negative stiffness structure of the magnetic force is reduced by optimization.In parallel with air spring structure negative magnetic stiffness structure reduces the natural frequency of the vibration isolation platform of the grating ruling machine is to less than 1 Hz.(3)The dynamic model of six degrees of freedom of the vibration isolation platform is established,and the dynamic model is transformed into six single input and single output models by decoupling.Based on the PID control,the fuzzy neural network topology is introduced to solve the problem that PID can not adjust the parameters,and the fuzzy neural network PID controller is constructed.The simulation results show that the fuzzy neural network PID controller can achieve better vibration isolation effect.