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

Author(s):  
Xianqing Wu ◽  
Kexin Xu

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.

2021 ◽  
Vol 2087 (1) ◽  
pp. 012056
Author(s):  
Dechun Zhao ◽  
Yansong Song ◽  
Yang Liu ◽  
Baishuo Zhang ◽  
Tianci Liu

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.


2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879574 ◽  
Author(s):  
Wei Yuan ◽  
Guoqin Gao

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.


2019 ◽  
Vol 9 (16) ◽  
pp. 3290 ◽  
Author(s):  
Hoai Vu Anh Truong ◽  
Duc Thien Tran ◽  
Xuan Dinh To ◽  
Kyoung Kwan Ahn ◽  
Maolin Jin

The paper proposes an adaptive fuzzy position control for a 3-DOF hydraulic manipulator with large payload variation. The hydraulic manipulator uses electrohydraulic actuators as primary torque generators to enhance carrying payload of the manipulator. The proposed control combines backstepping sliding mode control, fuzzy logic system (FLS), and a nonlinear disturbance observer. The backstepping sliding mode control includes a sliding mode control for manipulator dynamics and a PI control for actuator dynamics. The fuzzy logic system is utilized to adjust the control gain and robust gain of the sliding mode control (SMC) based on the output of the nonlinear disturbance observer to compensate the payload. The Lyapunov approach and backstepping technique are used to prove the stability and robustness of the whole system. Some simulations are implemented, and the results are compared to other controllers to exhibit the effectiveness of the proposed control.


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