Modeling and Control of Ultra Precision Positioning System for a Grating Ruling Machine

2011 ◽  
Vol 110-116 ◽  
pp. 2647-2654
Author(s):  
Yuan Shen ◽  
Dong Cai Liu ◽  
Guo Fu Lian ◽  
Jie Guo ◽  
Chan Gan Zhu

This paper presents a system modeling based control scheme of an ultra precision positioning system for a grating ruling machine. Since the positioning system having a long stroke with ultra precision, the positioning system consists of a coarse positioning stage driven by a servo motor and a fine positioning stage driven by a piezoelectric ceramic. In order to improve positional accuracy and remove the noise components of motion, a hybrid control scheme based on the system modeling is implemented. Considering position-dependent and time-dependent behaviors of the stages, a model based LQ controller is utilized to the coarse stage and a PID feedback controller based on neural network is utilized to the fine stage. Experiment results reveal the efficient and robust of the control scheme and show that the positional accuracy has been readily achieved within 8.6 nm.

2011 ◽  
Vol 87 ◽  
pp. 200-205 ◽  
Author(s):  
Jing Shu Wang ◽  
Li Ting Sun ◽  
Ming Chi Feng ◽  
Chang An Zhu

Base on the significance of understanding research objects, modeling and validation of ultra precision positioning system is studied in this paper. Taking different reduction methods of leaf springs into consideration, a rigid body model and an elastic body model has been developed. Identifying unknown parameters by the least square method, the validation results of two models are compared. The conclusion indicates that the elastic body model is better when the dynamic characteristics of the positioning system before the stable state are concerned and the rigid body model is more appropriate if the accuracy of the whole model is focused.


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