scholarly journals Disturbance-observer-based attitude control under input nonlinearity

Author(s):  
Umair Javaid ◽  
Hongyang Dong

A disturbance observer-based control scheme is proposed in this paper to deal with the attitude stabilization problems of spacecraft subjected to external disturbances, parameter uncertainties, and input nonlinearities. Particularly, the proposed approach addresses the dead-zone issue, a non-smooth nonlinearity affiliated with control input that significantly increases controller design difficulties. A novel nonlinear disturbance observer (NDO) is developed, which relaxes the strong assumption in conventional NDO design that disturbances should be constants or varying with slow rates. After that, a special integral sliding mode controller (ISMC) is combined with the NDO to achieve asymptotic convergence of system states. Simulations are performed in the presence of time-varying disturbances, parameter uncertainties, and dead-zone nonlinearity to justify the effectiveness of the proposed control scheme.

Author(s):  
Lijun Han ◽  
Guoyuan Tang ◽  
Ruikun Xu ◽  
Hui Huang ◽  
De Xie

In this paper, a fractional integral sliding mode control (FISMC) strategy with a disturbance observer (DO) is proposed for the trajectory tracking problem of the underwater manipulator, under lumped disturbances namely parameter uncertainties and external disturbances. The modified fractional integral sliding mode surface (FISMS) is designed to guarantee the fast convergence of system states. The DO method and the second-order sliding mode control law are used in the controller design, in which the former is introduced to compensate the effect of the lumped disturbances. Also, a saturated function is selected to replace the sign function to attenuate the chattering phenomenon. The stability of the overall closed-loop system is proved via Lyapunov’s finite-time stability theory. Numerical simulations are performed on a 6 degree of freedom (DOF) underwater manipulator. Simulation results demonstrate that the proposed control scheme can achieve better tracking performance and stronger robustness against disturbances, by comparing with the DO-based PD control and the DO-based PID-type linear sliding mode control (SMC).


2015 ◽  
Vol 23 (15) ◽  
pp. 2470-2477 ◽  
Author(s):  
Zhen Wang ◽  
Zhong Wu ◽  
Lijun Li ◽  
Jun Yuan

Abstract: There exist multiple disturbances resulting from the structural vibrations of flexible appendages, unknown external and internal disturbances, and parameter uncertainties, which affect the attitude control performance seriously. To enhance the disturbance attenuation performance and vibration suppression ability, a composite anti-disturbance control scheme (CADCS) based on disturbance observer is proposed for attitude stabilization and vibration reduction of flexible spacecraft. The CADCS combines a composite disturbance observer (CDO) and a PD controller with feedforward. The multiple disturbances are equivalent to slowly varying disturbance and harmonic disturbance. The CDO can estimate two types of disturbance and compensate for them through feedforward. The PD controller realizes the asymptotic convergence by compensating the disturbance from CDO. The CADCS based on CDO and PD controller is not only simple and easy to realize, but also yields better vibration suppression and anti-disturbance performance. Simulation results of a certain spacecraft demonstrate the effectiveness of the proposed CADCS.


2013 ◽  
Vol 284-287 ◽  
pp. 2296-2300 ◽  
Author(s):  
Kuang Shine Yang ◽  
Chi Cheng Cheng

The quadrotor helicopter is designed to easily move in particular environments because it can take off and land in limited space and easily hover at a fixed location. For this reason, a robust adaptive sliding mode controller is developed to control of a quadrotor helicopter in the presence of external disturbances and parameter uncertainties. The quadrotor helicopter system is a typical underactuated system, which has fewer independent control actuators than degrees of freedom to be controlled. The main contribution here is to afford simulation and verification for the quadrotor helicopter flight controller under the assumption of unknown parameters. By utilizing the Lyapunov stability theorem, we can achieve asymptotic tracking of desired reference commands for the quadrotor helicopter, which is subject to both external disturbances and parametric uncertainties. From the simulation results, the controller was sufficient to achieve position and attitude control of the quadrotor helicopter system, which permits possible real time applications in the near future.


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Naibao He ◽  
Changsheng Jiang ◽  
Bin Jiang ◽  
Qian Gao

A novel flight control scheme is proposed using the terminal sliding mode technique, unidirectional auxiliary surfaces and the disturbance observer model. These proposed dynamic attitude control systems can improve control performance of hypersonic vehicles despite uncertainties and external disturbances. The terminal attractor is employed to improve the convergence rate associated with the critical damping characteristics problem noted in short-period motions of hypersonic vehicles. The proposed robust attitude control scheme uses a dynamic terminal sliding mode with unidirectional auxiliary surfaces. The nonlinear disturbance observer is designed to estimate system uncertainties and external disturbances. The output of the disturbance observer aids the robust adaptive control scheme and improves robust attitude control performance. Finally, simulation results are presented to illustrate the effectiveness of the proposed terminal sliding mode with unidirectional auxiliary surfaces.


2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Qiang Qu ◽  
Fuyang Chen ◽  
Bin Jiang ◽  
Gang Tao

A novel self-repairing control scheme is proposed for a helicopter with unknown disturbance. Firstly, a disturbance observer is introduced to observe the disturbance of the system, which can produce corresponding control signals according to the disturbance signals. Secondly, an integral sliding mode controller is designed to compensate the unobserved disturbance and uncertainties. All of the closed-loop poles can be arbitrarily placed and the output errors converge to zero effectively through the controller. Besides, a robust closed-loop system against disturbance and parameter uncertainties is achieved. In addition, quantum information technique is used to increase the self-repairing control accuracy of helicopter. Finally, simulation results demonstrate the effectiveness and feasibility of the proposed self-repairing control scheme.


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jian Fu ◽  
Liangming Wang ◽  
Mou Chen ◽  
Sijiang Chang

A robust adaptive backstepping attitude control scheme, combined with invariant-set-based sliding mode control and fast-nonlinear disturbance observer, is proposed for the airbreathing hypersonic vehicle with attitude constraints and propulsive disturbance. Based on the positive invariant set and backstepping method, an innovative sliding surface is firstly developed for the attitude constraints. And the propulsive disturbance of airbreathing hypersonic vehicle is described as a differential equation which is motivated by attitude angles in this paper. Then, an adaptive fast-nonlinear disturbance observer for the proposed sliding surface is designed to estimate this kind of disturbance. The convergence of all closed-loop signals is rigorously proved via Lyapunov analysis method under the developed robust attitude control scheme. Finally, simulation results are given to illustrate the effectiveness of the proposed attitude control scheme.


Author(s):  
Ming You ◽  
Qun Zong ◽  
Bailing Tian ◽  
Fanlin Zeng

The controller design for reusable launch vehicles is challenging due to enormous amounts of model parameter uncertainties and atmospheric disturbances. This paper first derives six-degree-of-freedom model of a reusable launch vehicle with atmospheric disturbances. Next, four kinds of atmospheric disturbances are introduced and wind models are established respectively. For attitude control of the reusable launch vehicle, a nonsingular terminal sliding mode controller is designed with stability guaranteed. Finally, simulation results show a satisfactory performance for the attitude tracking of the reusable launch vehicle with atmospheric disturbances.


Author(s):  
Afef Hfaiedh ◽  
Ahmed Chemori ◽  
Afef Abdelkrim

In this paper, the control problem of a class I of underactuated mechanical systems (UMSs) is addressed. The considered class includes nonlinear UMSs with two degrees of freedom and one control input. Firstly, we propose the design of a robust integral of the sign of the error (RISE) control law, adequate for this special class. Based on a change of coordinates, the dynamics is transformed into a strict-feedback (SF) form. A Lyapunov-based technique is then employed to prove the asymptotic stability of the resulting closed-loop system. Numerical simulation results show the robustness and performance of the original RISE toward parametric uncertainties and disturbance rejection. A comparative study with a conventional sliding mode control reveals a significant robustness improvement with the proposed original RISE controller. However, in real-time experiments, the amplification of the measurement noise is a major problem. It has an impact on the behaviour of the motor and reduces the performance of the system. To deal with this issue, we propose to estimate the velocity using the robust Levant differentiator instead of the numerical derivative. Real-time experiments were performed on the testbed of the inertia wheel inverted pendulum to demonstrate the relevance of the proposed observer-based RISE control scheme. The obtained real-time experimental results and the obtained evaluation indices show clearly a better performance of the proposed observer-based RISE approach compared to the sliding mode and the original RISE controllers.


Sign in / Sign up

Export Citation Format

Share Document