scholarly journals Backstepping Control of an Unmanned Helicopter Subjected to External Disturbance and Model Uncertainty

2021 ◽  
Vol 11 (12) ◽  
pp. 5331
Author(s):  
Wenlong Zhao ◽  
Zhijun Meng ◽  
Kaipeng Wang ◽  
Haoyu Zhang

A helicopter is a highly nonlinear system. Its mathematical model is difficult to establish accurately, especially the complicated flapping dynamics. In addition, the forces and moments exerted on the fuselage are very vulnerable to external disturbances like wind gust when flying in the outdoor environment. This paper proposes a composite control scheme which consists of a nonlinear backstepping controller and an extended state observer (ESO) to handle the above problems. The stability of the closed-loop system can be guaranteed based on Lyapunov theory. The external disturbances and model nonlinearities are treated as a lumped disturbance. Meanwhile, the ESO is employed to compensate the influence by estimating the lumped disturbance in real-time. Numerical simulation results are presented to demonstrate that the algorithm can achieve accurate and agile attitude tracking under the external wind gust disturbances even with model uncertainties. When coming to the flight test, a block dropping device was designed to generate a quantifiable and replicable disturbance, and the experimental results indicate that the algorithm introduced above can reject the external disturbance rapidly and track the given attitude command precisely.

Author(s):  
Walid Alqaisi ◽  
Yassine Kali ◽  
Jawhar Ghommam ◽  
Maarouf Saad ◽  
Vahé Nerguizian

This paper proposes an improved non-singular terminal super-twisting control for the problem of position and attitude tracking of quadrotor systems suffering from uncertainties and disturbances. The super-twisting algorithm is a second-order sliding mode known to be a very effective control used to provide high precision and less chattering for uncertain nonlinear electromechanical systems. The proposed method is based on a non-singular terminal sliding surface with new exponent that solves the problem of singularity. The design procedure and the stability analysis of the closed-loop system using Lyapunov theory are detailed for the considered system. Finally, the proposed control scheme is tested in simulations and by experiments on the parrot-rolling spider quadrotor. Moreover, a comparison is made with the standard super-twisting algorithm in the simulation part. The results obtained show adequate performance in trajectory tracking and chattering reduction.


2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Li Ding ◽  
Qing He ◽  
Chengjun Wang ◽  
Rongzhi Qi

In this article, an attitude tracking controller is designed for a quadrotor unmanned aerial vehicle (UAV) subject to lumped disturbances. Firstly, the attitude dynamical model of the quadrotor under external disturbances is established. Subsequently, an improved sliding mode control (SMC) strategy is designed based on the linear extended state observer (LESO). In this control scheme, the SMC will guarantee the sliding surface is finite time reachable and the LESO will estimate and compensate for the lumped disturbances. Then, the robustness and asymptotic stability of the proposed controller are proved by the stability analyses. Finally, three numerical simulation cases and comparative flight experiments validate the effectiveness of the developed controller.


2021 ◽  
Vol 11 (7) ◽  
pp. 3257
Author(s):  
Chen-Huan Pi ◽  
Wei-Yuan Ye ◽  
Stone Cheng

In this paper, a novel control strategy is presented for reinforcement learning with disturbance compensation to solve the problem of quadrotor positioning under external disturbance. The proposed control scheme applies a trained neural-network-based reinforcement learning agent to control the quadrotor, and its output is directly mapped to four actuators in an end-to-end manner. The proposed control scheme constructs a disturbance observer to estimate the external forces exerted on the three axes of the quadrotor, such as wind gusts in an outdoor environment. By introducing an interference compensator into the neural network control agent, the tracking accuracy and robustness were significantly increased in indoor and outdoor experiments. The experimental results indicate that the proposed control strategy is highly robust to external disturbances. In the experiments, compensation improved control accuracy and reduced positioning error by 75%. To the best of our knowledge, this study is the first to achieve quadrotor positioning control through low-level reinforcement learning by using a global positioning system in an outdoor environment.


Author(s):  
Yiqi Xu

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.


2014 ◽  
Vol 631-632 ◽  
pp. 710-713 ◽  
Author(s):  
Xian Yong Wu ◽  
Hao Wu ◽  
Hao Gong

Anti-synchronization of two different chaotic systems is investigated. On the basis of Lyapunov theory, adaptive control scheme is proposed when system parameters are unknown, sufficient conditions for the stability of the error dynamics are derived, where the controllers are designed using the sum of the state variables in chaotic systems. Numerical simulations are performed for the Chen and Lu systems to demonstrate the effectiveness of the proposed control strategy.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yassine El Houm ◽  
Ahmed Abbou ◽  
Moussa Labbadi ◽  
Mohamed Cherkaoui

This paper deals with the design of a novel modified supertwisting fast nonlinear sliding mode controller (MSTFNSMC) to stabilize a quadrotor system under time-varying disturbances. The suggested control strategy is based on a modified supertwisting controller with a fast nonlinear sliding surface to improve the tracking performance. The paper suggests a simple optimization tool built-in MATLAB/Simulink to tune the proposed controller parameters. Fast convergence of state variables is established by using a nonlinear sliding surface for rotational and translational subsystems. The modified supertwisting controller is developed to suppress the effect of chattering, reject disturbances, and ensure robustness against external disturbance effect. The stability of the proposed controller (MSTFNSMC) is proved using the Lyapunov theory. The performance of the proposed MSTFNSMC approach is compared with the supertwisting sliding mode controller (STSMC) by numerical simulations to verify its effectiveness.


2013 ◽  
Vol 709 ◽  
pp. 583-588
Author(s):  
Jin Hua Ye ◽  
Di Li ◽  
Shi Yong Wang ◽  
Feng Ye

This paper develops a high performance guidance controller for automated guided vehicle (AGV) with nonholonomic constraint. In this controller, the path following method in the Serret-Frenet frame is used for driving the AGV onto a predefined path at a constant forward speed. Moreover, a first order dynamic sliding mode controller is proposed, not only to overcome the impact of unknown model uncertainties and external disturbances of the system, but also to weaken the chattering in the standard sliding mode control. The global asymptotic stability and robustness of the system is proven by the Lyapunov theory and LaSalles invariance principle. Simulation results show the validity of the proposed guidance control scheme.


Author(s):  
Yi Min Zhao ◽  
Yu Lin ◽  
Fengfeng Xi ◽  
Shuai Guo ◽  
Puren Ouyang

The robotic riveting system requires a rivet robotic positioning process for rivet-in-hole insertions, which can be divided into two stages: rivet path-following and rivet spot-positioning. For the first stage, varying parameter-linear sliding surfaces are proposed to achieve robust rivet path-following against robot errors and external disturbances of the robotic riveting system. For the second stage, a second-order sliding surface is applied to attain accurate rivet spot-positioning within a finite time required by the riveting process. In order to improve the dynamic performance of the robot riveting system, the motion of robot end-effector between the two adjacent riveting spots has been properly designed. Overall, the proposed control scheme can guarantee not only the stability of the robot control system but also the robust rivet path-following and quick rivet spot-positioning in the presence of the robot errors and external disturbances of the robotic riveting system. The simulation and experimental results demonstrate the effectiveness of the proposed control scheme.


2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Guangli Zhou ◽  
Yongming Yao ◽  
Huiying Liu ◽  
Xupeng Bai ◽  
Jianbo Liu

In this paper, we presented a strategy for accurate trajectory tracking control of a quadrotor with unknown disturbances. To guarantee that the tracking errors of all system state variables converge to zero in finite time and eliminate the chattering phenomenon caused by the switching control action, a control strategy that combines linear prediction model of disturbances and fuzzy sliding mode control (SMC) based on logical framework with side conditions (LFSC) was designed. LFSC was applied for both position and attitude tracking of the quadrotor. Firstly, a linear prediction method was devised to minimize the effects of external disturbances. Secondly, a new fuzzy law was implemented to eliminate the chattering phenomenon. In addition, the stabilities of position and attitude were demonstrated by using Lyapunov theory, respectively. Simulation results and comprehensive comparisons demonstrated the superior performance and robustness of the proposed LFSC scheme in the case of external disturbances.


2018 ◽  
Vol 41 (2) ◽  
pp. 405-416 ◽  
Author(s):  
Haitao Chen ◽  
Shenmin Song ◽  
Xuehui Li

This paper studies the finite time spacecraft attitude tracking control problem, while considering modeling uncertainty, external disturbances and control input saturation. A novel integral terminal sliding mode surface (ITSMS) is designed by combining the fast terminal sliding mode surface (FTSMS) with a low pass filter to achieve a fast finite time convergence rate for the control system, without input singularity. An auxiliary signal is used to compensate for the effects of actuator saturation. The basic controller is first formulated based on the ITSMS, fast-TSM-type reaching law and auxiliary system, in the presence of an external disturbance and input saturation. Then, an adaptive control procedure is introduced, which simultaneously handles modeling uncertainty and external disturbance, thereby creating an adaptive attitude tracking controller. The proposed controller provides a fast finite time convergence rate for the control system, based on the newly designed ITSMS, while simultaneously compensating for modeling uncertainty, external disturbances and input saturation, without restricting the parameter selection process nor requiring repeated differentiation of nonlinear functions. Finally, digital simulation results are presented and demonstrate the effectiveness of the proposed controllers.


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