Ultra-precision motion system feedforward controller parameter tuning method

Abstract

The invention discloses an ultra-precision motion system feedforward controller parameter tuning method. If the DC gain of a feedback controller is finite, a tracking error is proportional to the N-order derivative of a reference trajectory, that is, the tracking error and the N-order derivative of the reference trajectory have the same shape, the feedforward coefficient of the N-order derivativeis judged to be inaccurate, a bisection method is used to tune the feedforward coefficient of the N-order derivative until the shape of the tracking error is the same as the (N+1)-order derivative ofthe reference trajectory, and an accurate N-order derivative feedforward coefficient can be obtained; and if the DC gain of the feedback controller is infinite and only contains a first-order integral, the tracking error is proportional to the (N+1)-order derivative of the reference trajectory, the feedforward coefficient of the N-order derivative is judged to be inaccurate, the bisection method is used to tune the feedforward coefficient of the N-order derivative until the shape of the tracking error is the same as the (N+2)-order derivative of the reference trajectory, and an accurate N-order derivative feedforward coefficient can be obtained, and N is increased gradually with a step 1 from 2 until the tracking error meets requirements. The tracking errors in acceleration and deceleration regions can be greatly reduced, the building time is reduced, and the system yield is enhanced.

Description

technical field [0001] The patent relates to a parameter setting method of a feedforward controller of an ultra-precision motion system, which belongs to the field of ultra-precision motion control. Background technique [0002] Ultra-precision motion systems are widely used in high-end manufacturing equipment and instruments such as lithography machine workpiece tables, atomic force microscopes, and scanning tunneling microscopes. A single working cycle of this type of motion system will successively go through three intervals: acceleration domain, constant speed domain and deceleration domain. After the acceleration domain or deceleration domain ends, the time required for the error to converge to within the specified accuracy range is the setup time. Subsequent operations can only be performed after the error converges. Work, the length of the establishment time directly affects the system productivity, and reducing the establishment time has important theoretical and app...

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Problems solved by technology

Feedforward controllers are generally designed according to the model obtained from system identification, and there are inevitably errors in system identification, so it is difficult to obtain real model paramet

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