scholarly journals Research on control technology of tip-tilt mirror system in adaptive optics

2021 ◽  
Vol 2087 (1) ◽  
pp. 012056
Author(s):  
Dechun Zhao ◽  
Yansong Song ◽  
Yang Liu ◽  
Baishuo Zhang ◽  
Tianci Liu
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Sliding Mode ◽  
Tracking Error ◽  
Mirror System ◽  
Nonlinear Observer ◽  
Nonlinear Disturbance Observer ◽  
Mode Control ◽  
Nonlinear Disturbance

Abstract In order to solve the control problem of the tip-tilt mirror under the unknown disturbance, a nonlinear disturbance observer with adaptive ability based on the sliding mode control is designed.Firstly, the sliding mode control method of the tip-tilt mirror system is established with Lyapunov functions. Secondly, an adaptive nonlinear disturbance observer is developed on a basis of observer model. Finally, the proposed sliding mode control method is combined with a nonlinear observer with adaptive capability to achieve the goal of improving the control accuracy of the system, while also reducing the chattering caused by the system. The experiment proves that this method is achievable. The experimental results show that the tracking error of the azimuth axis is reduced from 1.637μrad to 1.083μrad, and the accuracy is improved by about 51.2%. The tracking error of the pitch axis is reduced from 1.966μrad to 1.614μrad, and the accuracy is improved by about 21.8%. This method can greatly weaken the inherent chattering and external disturbance of the system, and improve the stability of the tip-tilt mirror system.

Global sliding mode control for the underactuated translational oscillator with rotational actuator system

2020 ◽  
pp. 095965182094613
Author(s):  
Xianqing Wu ◽  
Kexin Xu
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Sliding Mode ◽  
Nonlinear Disturbance Observer ◽  
Mode Control ◽  
Global Sliding Mode Control ◽  
Actuator System ◽  
Nonlinear Disturbance ◽  
Rotational Actuator

This article is motivated by the control issues of the translational oscillator with rotational actuator system in the existence of uncertain disturbances. A nonlinear disturbance observer and a global sliding mode control method are proposed for the disturbance estimation and stabilization of the translational oscillator with rotational actuator system. Compared with the existing control methods, uncertain disturbances are estimated by the proposed nonlinear disturbance observer. In addition, the sliding mode control method is continuous and global robustness with respect to disturbances. Specifically, to facilitate the controller design, the dynamics of the translational oscillator with rotational actuator system are rearranged as the cascade form first. Then, a virtual signal is constructed and corresponding error dynamics are derived. Subsequently, a nonlinear disturbance observer and a continuous global sliding mode control method are proposed for the disturbance rejection and stabilization of the translational oscillator with rotational actuator system. Finally, simulation results are provided to verify the effectiveness and robustness of the proposed controller.

Adaptive nonlinear observer–based sliding mode control of robotic manipulator for handling an unknown payload

2020 ◽  
pp. 095965182096946
Author(s):  
Guiying Li ◽  
Shuyang Wang ◽  
Zhigang Yu
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Design Procedure ◽  
Nonlinear Observer ◽  
Control Synthesis ◽  
Unknown Constant ◽  
Nonlinear Disturbance Observer ◽  
Mode Control ◽  
Nonlinear Disturbance

This article presents the control synthesis of robotic manipulators with an unknown constant payload. A novel nonlinear disturbance observer with an adaptive scheme is designed to estimate the external force induced by the unknown constant payload. A general design procedure for designing the gain of the nonlinear observer is developed rather than the time-consuming trials and error to choose proper gain. The nonlinear observer gain is designed using an adaptive technique to extend the applicability of the disturbance observer. The stability of the proposed observer is established using Lyapunov method under certain conditions. The proposed nonlinear disturbance observer will be integrated with the sliding mode control to substantially alleviate the chattering problem. Also, simulation results are presented to verify the effectiveness of the proposed methods.

scholarly journals Sliding mode control of the automobile electro-coating conveying mechanism with a nonlinear disturbance observer

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879574 ◽  
Author(s):  
Wei Yuan ◽  
Guoqin Gao
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
High Performance ◽  
Sliding Mode ◽  
External Disturbance ◽  
Nonlinear Disturbance Observer ◽  
Control Approach ◽  
Mode Control ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

The trajectory-tracking performance of the automobile electro-coating conveying mechanism is severely interrupted by highly nonlinear crossing couplings, unmodeled dynamics, parameter variation, friction, and unknown external disturbance. In this article, a sliding mode control with a nonlinear disturbance observer is proposed for high-accuracy motion control of the conveying mechanism. The nonlinear disturbance observer is designed to estimate not only the internal/external disturbance but also the model uncertainties. Based on the output of the nonlinear disturbance observer, a sliding mode control approach is designed for the hybrid series–parallel mechanism. Then, the stability of the closed-loop system is proved by means of a Lyapunov analysis. Finally, simulations with typical desired trajectory are presented to demonstrate the high performance of the proposed composite control scheme.

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