scholarly journals Disturbance Observer-Based Adaptive Control of Hypersonic Vehicles with Constrained Actuators

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Guan Wang ◽  
Li Li ◽  
Weihua Li ◽  
Huajun Zhou ◽  
Changbo Ma ◽  
...  
Keyword(s):  
Disturbance Observer ◽  
Input Saturation ◽  
Adaptive Controller ◽  
Hypersonic Vehicles ◽  
Control Allocation ◽  
External Disturbances ◽  
Nonlinear Disturbance Observer ◽  
Aerodynamic Control ◽  
Actuator Constraints ◽  
Control Surfaces

This study investigates an adaptive controller for the flexible air-breathing hypersonic vehicles (AHVs) subject to external disturbances and actuator constraints. The combination of nonlinear disturbance observer and adaptive mechanism is exploited to design an adaptive controller for each subsystem. For the velocity subsystem, an auxiliary system is employed to handle the scramjet input saturation issue. For the altitude subsystem, the magnitude/rate constraints and the dynamics of aerodynamic control surfaces are addressed by the control allocation module. Simulations show the effectiveness of the proposed control.

scholarly journals Output Feedback Control for Asymptotic Stabilization of Spacecraft with Input Saturation

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Chutiphon Pukdeboon
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Control Method ◽  
Input Saturation ◽  
Output Feedback Control ◽  
Velocity Measurements ◽  
External Disturbances ◽  
Nonlinear Disturbance Observer ◽  
Rigid Spacecraft ◽  
Actuator Constraints

This paper investigates the attitude stabilization problem of rigid spacecraft subject to actuator constraints, external disturbances, and attitude measurements only. An output feedback control framework with input saturation is proposed to solve this problem. The general saturation function is utilized in the proposed controller design and a unified control method is developed for the asymptotic stabilization of rigid spacecraft without velocity measurements. Asymptotic stability is proven by Lyapunov stability theory. Moreover, a new nonlinear disturbance observer is designed to compensate for external disturbances. Then, a composite controller is presented by combining a unified saturated output feedback control with a nonlinear disturbance observer. Desirable features of the proposed control scheme include the intuitive structure, robustness against external disturbances, avoidance of model information and velocity measurements, and ability to ensure that the actuator constraints are not violated. Finally, numerical simulations have been carried out to verify the effectiveness of the proposed control method.

A fault-tolerant attitude tracking control of spacecraft using an anti-unwinding robust nonlinear disturbance observer

2019 ◽  
Vol 233 (16) ◽  
pp. 6005-6018 ◽  
Author(s):  
Syed Muhammad Amrr ◽  
M Nabi ◽  
Pyare Mohan Tiwari
Keyword(s):  
Disturbance Observer ◽  
Controller Design ◽  
Simulation Analysis ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Actuator Faults ◽  
External Disturbances ◽  
Nonlinear Disturbance Observer ◽  
Attitude Tracking ◽  
Nonlinear Disturbance

This paper investigates the application of an integral sliding mode control with a robust nonlinear disturbance observer to obtain an anti-unwinding spacecraft attitude tracking response with robustness against external disturbances, inertia matrix uncertainties, and actuator faults. In the controller design, external disturbances, uncertainties, and actuator faults are lumped together and estimated by the robust nonlinear disturbance observer. The proposed robust nonlinear disturbance observer guarantees the convergence of estimated lumped disturbance error to origin in finite time. The estimated disturbance is then used in the controller as a feed-forward compensator. Further, an adaptive law is also incorporated in the proposed controller to ensure additional robustness. The stability of the overall system and anti-unwinding characteristic are proved using the Lyapunov stability theory. Finally, numerical simulation analysis is performed in the presence of all the sources of lumped disturbances. It is observed that the proposed control strategy is ensuring higher accuracy, good steady-state precision, and eliminates the unwinding phenomenon.

scholarly journals Suppression the Disturbance of Robotic Manipulators Based on Nonlinear Disturbance Observer and Fuzzy Logic System

2020 ◽  
Vol 24 (7) ◽  
pp. 846-854
Author(s):  
Wangyong He ◽  
Haogui Li ◽  
Yuanjiang Wang ◽  
Sanqiu Liu ◽  
◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Disturbance Observer ◽  
Robot Manipulator ◽  
Robotic Manipulators ◽  
Fuzzy Logic System ◽  
External Disturbances ◽  
Nonlinear Disturbance Observer ◽  
Coupling System ◽  
Nonlinear Disturbance ◽  
Logic System

Robotic Manipulators (RM) are nonlinear and coupling system with time-variant and model uncertainties. In addition, RM are subject to different types of disturbances in practice, such as joint frictions, unknown payloads, and interferences from external systems. In this paper, these adverse factors are regarded as disturbance, and classifies them into internal disturbances and external disturbances. In order to achieve high-precision control, a Nonlinear Disturbance Observer (NDO) is designed to suppress external disturbances, and a Fuzzy Logic System (FLS) is designed to compensate internal disturbances. The scheme can effectively suppress the disturbance and improve the control accuracy. The validity of the scheme is shown by computer simulations of a two-link robot manipulator.

Robust Backstepping Tracking Control of Mobile Robot Based on Nonlinear Disturbance Observer

2016 ◽  
Vol 6 (2) ◽  
pp. 901 ◽  
Author(s):  
Mahmood Ali Moqbel Obaid ◽  
Abdul Rashid Husain ◽  
Ali Abdo Mohammed Al-kubati
Keyword(s):  
Fuzzy Logic ◽  
Mobile Robot ◽  
Disturbance Observer ◽  
The State ◽  
Tracking Errors ◽  
External Disturbances ◽  
Velocity Signal ◽  
Nonlinear Disturbance Observer ◽  
State Tracking ◽  
Nonlinear Disturbance

This paper presents a robust backstepping control (BC) method based on nonlinear disturbance observer (NDOB) for trajectory tracking of the nonholonomic wheeled mobile robot (WMR) in the presence of external disturbances and parameters uncertainties. At first, a bounded Fuzzy logic based backstepping controller (BFLBC) is designed to control the WMR without considering the effects of the external disturbances and the parameters uncertainties. Typically, the conventional BC controller depends upon the state tracking errors analysis, where unbounded velocity signal is produced for the applications that have huge tracking errors. Therefore, a fuzzy logic controller (FLC) is introduced in this research in order to normalize the state tracking errors, so that the input errors to the BC are bounded to a finite interval. Finally, the designed BFLBC is integrated with the nonlinear disturbance observer in order to attenuate the external disturbances and model uncertainties. The simulation results show the effectiveness of the proposed controller to generate a bounded velocity signal as well as to stabilize the tracking errors to zero. In addition, the results prove that the proposed controller provide an excellent disturbance attenuation as well as robustness against the parameters uncertainties.

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