Image measurement-based two-stage control of Stewart platform

Zhang Liangzong; Yang Tao; Wu Yun; Tang Tao

doi:10.12086/oee.2022.220019

Article navigation > Opto-Electronic Engineering > 2022 Vol. 49 > No. 8 > 220019

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Zhang L Z, Yang T, Wu Y, et al. Image measurement-based two-stage control of Stewart platform[J]. Opto-Electron Eng, 2022, 49(8): 220019. doi: 10.12086/oee.2022.220019

Citation:

Zhang L Z, Yang T, Wu Y, et al. Image measurement-based two-stage control of Stewart platform[J]. Opto-Electron Eng, 2022, 49(8): 220019. doi: 10.12086/oee.2022.220019

Image measurement-based two-stage control of Stewart platform

1.
Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
2.
Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
3.
University of Chinese Academy of Sciences, Beijing 100049, China

Fund Project: Sichuan Province Science and Technology Support Program (100012542)

More Information

Corresponding author: taotang@ioe.ac.cn

Received Date 16 March 2022

Revised Date 05 May 2022

Accepted Date 20 May 2022

Available Online 22 July 2022

Published Date 25 August 2022

Abstract

Abstract

The Stewart platform has six degrees of freedom motion characteristics and can be used as both vibration isolation and tracking platform. However, the vibration isolation function requires low system bandwidth, while the tracking function requires high system bandwidth, which makes it difficult to achieve high precision tracking using the Stewart platform with vibration isolation function. To solve this technical problem, a high-bandwidth tilt correction system is introduced to form a two-stage control structure, so as to improve the accuracy. The traditional two-stage control needs to design decoupling link and independent measurement sensors to achieve hierarchical control. In this paper, a control method based on a single sensor is proposed to improve the traditional dual-order structure to avoid decoupling and achieve a high-precision closed-loop for the Stewart-TTM. In order to further improve the tracking accuracy of the system at low frequencies, a PI-PI controller is designed. Theoretical analysis and experimental verification show that the Stewart dual-stage control structure based on image measurement can not only meet the requirements of vibration isolation, but also achieve high-precision tracking control. Compared with the traditional PI controller, the PI-PI control proposed in the tilt correction system can effectively improve the tracking accuracy.
- Stewart platform /
- two-stage system /
- PI-PI control

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References

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Overview

Overview

It is a trend of development to use the Stewart platform as a means of space. But the Stewart platform, which has a vibration ability and low system bandwidth, causing the tracking accuracy to be difficult to improve. In response to this problem, many scholars have proposed a two-stage control system, which is to design the system of a system that is far higher than the Stewart platform, which is used to curb the tracking error of the Stewart platform, thereby improving the tracking accuracy of the system. Tip-tit-mirror (TTM) bandwidth is very high, available in the intensive subsystem and the Stewart platform for two-stage control. When the system has only one CCD as a detector, it is necessary to design the decoupling link to make the system stable. But for the traditional two-order structure, it is difficult to design the decoupling element as the object of the probe. Therefore, this paper analyzes the traditional two-order structure and removes the redundant control structure. This paper also obtains the new structure based on the two-stage control of the position output and makes the decoupling link becomes easy. Through theoretical analysis, the accuracy of the system is mainly due to the ability of the precision subsystem to suppress the error of the rough system. The traditional controller of the advanced subsystem is the PI controller, which is extremely limited to the accuracy of the precision. The current research on the accuracy of the TTM tracking accuracy is mainly by introducing additional hardware devices, but this increases the uncertainty of the system stability. Therefore, the design of the PI-PI controller can effectively improve the tracking accuracy while increasing the cost of the system. After theoretical analysis and experimental verification, the PI-PI controller, compared to the PI controller, can improve the suppression ability of the error of the precision subsystem in the low frequencies. The double order structure control of the system and the Stewart platform is made up of the system, which makes the tracking precision of the system significantly improved, which is better solved the problem of the Stewart platform tracking precision that has the vibration function.