Method for compensating frictional error of servo system of numerical control machine tool

Abstract

The invention discloses a device and a method for compensating a frictional error of a servo system of a numerical control machine tool. Position feedback control and friction feedforward compensation are realized to further eliminate the frictional error by adopting a multi-sampling rate control structure of a discrete system. In the multi-sampling rate control structure, the sampling frequency of friction feedforward is required to be higher than that of position feedback. The multi-sampling rate control structure can realize a detailed friction feedforward compensation function in the position feedback under the condition of not changing the structure and stability of a servo feed control system. In the calculation of the amount of detailed friction feedforward compensation, the output of a position interpolator of the servo feed control system is utilized to obtain more detailed compensation speed instruction input by a linear interpolation method, and the amplitude change of a frictional force is predicted and the amount of the compensation is determined by adopting an exponential friction model. In the compensation method, the characteristics of the multi-sampling rate control structure and the structure of the servo system are fully utilized to improve the output accuracy and output frequency of the friction compensation, thereby achieving a more accurate friction compensation effect.

Description

technical field [0001] The invention belongs to the technical field of numerical control machine tools, and relates to an error compensation method, in particular to a friction error compensation method for a servo system of a numerical control machine tool. Background technique [0002] Friction is a strong and unavoidable external disturbance factor in the servo feed system of CNC machine tools. The error phenomena caused by friction will seriously limit the realization of high-precision control of CNC machine tools. Therefore, the elimination and control of friction errors in servo systems has always been a hot and difficult point in the research of high-speed and high-precision numerical control technology. Due to the strong nonlinear characteristics of friction, it is difficult for the general linear feedback control method to solve the error characteristics of friction under high speed and commutation conditions. Using the feed-forward compensation method based on th...

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Problems solved by technology

[0003] However, for the application conditions such as CNC machine tool servo system, the motion path has high motion speed and acceleration requirements, frequent speed changes are required, and the friction force changes strongly. The compensation strategy of simple and direct compensation has less action time and the compensation The effect is limited

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