scholarly journals Robust Discrete-Time Nonlinear Attitude Stabilization of a Quadrotor UAV Subject to Time-Varying Disturbances

2021 ◽  
Author(s):  
Fatih Adiguzel ◽  
Tarik Veli Mumcu
Keyword(s):  
Discrete Time ◽  
Disturbance Observer ◽  
Uncertain System ◽  
Time Varying ◽  
Input Output ◽  
Parameter Uncertainties ◽  
Nonlinear Disturbance Observer ◽  
Nonlinear Disturbance ◽  
Quadrotor System ◽  
Input Output Linearization

A discrete-time improved input/output linearization controller based on a nonlinear disturbance observer is considered to secure the stability of a four-rotor unmanned aerial vehicle under constant and time-varying disturbances, as well as uncertain system parameters for its attitude behaviour. Due to the nature of the quadrotor system, it contains the most extreme high level of nonlinearities, system parameter uncertainties (perturbations), and it has to cope with external disturbances that change over time. In this context, an offset-less tracking for the quadrotor system is provided with the input/output linearization controller together with a discrete-time pre-controller. In addition, the robustness of the system is increased with a discrete-time nonlinear disturbance observer for time-varying disturbances affecting the system. The main contribution of this study is to provide highly nonlinearities cancellation to guarantee the aircraft attitude stability and to propose a robust control structure in discrete-time, considering all uncertainties. Various simulation studies have been carried out to illustrate the robustness and effectiveness of the proposed controller structure.

scholarly journals Novel Adaptive Sliding Mode Control with Nonlinear Disturbance Observer for SMT Assembly Machine

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Rongrong Qian ◽  
Minzhou Luo ◽  
Yao Zhao ◽  
Jianghai Zhao
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
Sliding Mode ◽  
Adaptive Sliding Mode Control ◽  
Sliding Surface ◽  
Parameter Uncertainties ◽  
Nonlinear Disturbance Observer ◽  
Adaptive Sliding Mode ◽  
Mode Control ◽  
Nonlinear Disturbance

This paper presents a novel adaptive sliding mode control based on nonlinear sliding surface with disturbance observer (ANSMC-DOB) for precision trajectory tracking control of a surface mount technology (SMT) assembly machine. A two-degree-of-freedom model with time-varying parameter uncertainties and disturbances is built to describe the first axial mode of the pick-place actuation axis of the machine. According to the principle of variable damping ratio coefficient which makes the system have a nonovershoot transient response and a short settling time in the second-order system, the nonlinear sliding surface is designed for the sliding mode control (SMC). Since the upper bound value of the disturbances is unknown, the adaptive gain estimation is applied to replace the switching gain in the SMC. In order to settle the problem of SMC unrobust to the mismatched parameter uncertainties and disturbances, the nonlinear disturbance observer is introduced to estimate the mismatched disturbances and form the novel controller of ANSMC-DOB. The stability of sliding surfaces and control laws are verified by the Lyapunov functions. The simulation research and comparative experiments are conducted to verify the improvement of positioning accuracy and robustness by the proposed ANSMC-DOB in the SMT assembly machine.

Nonlinear disturbance observer-based control for a class of discrete-time stochastic systems with multiple heterogenous disturbances

2019 ◽  
Vol 42 (2) ◽  
pp. 180-187
Author(s):  
Hanxu Zhao ◽  
Xinjiang Wei ◽  
Huifeng Zhang ◽  
Hamid Reza Karimi
Keyword(s):  
Discrete Time ◽  
Disturbance Observer ◽  
Composite System ◽  
Stochastic Systems ◽  
Mean Square ◽  
Random Vectors ◽  
Nonlinear Disturbance Observer ◽  
Nonlinear Disturbance ◽  
Simulation Results

In this paper, the nonlinear disturbance observer-based control (NDOBC) scheme is proposed for a class of discrete-time stochastic systems with multiple heterogenous disturbances, which include the non-harmonic disturbance and a sequence of random vectors. A nonlinear disturbance observer (NDO) is designed to estimate the non-harmonic disturbance, then the NDOBC scheme is proposed by combining DOBC with [Formula: see text] control, such that the composite system can achieves asymptotically mean-square bounded and asymptotically mean-square stable in different conditions. Finally, simulation results show the effectiveness of the proposed method.

scholarly journals Nonlinear Disturbance-Observer-Based Sliding Mode Control for Flexible Air-Breathing Hypersonic Vehicles

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Na Wang ◽  
Xiu-Ming Yao ◽  
Wen-Shuo Li
Keyword(s):  
Disturbance Observer ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Hypersonic Vehicles ◽  
Sliding Mode Controller ◽  
Parameter Uncertainties ◽  
Nonlinear Disturbance Observer ◽  
Air Breathing ◽  
Nonlinear Disturbance ◽  
Uniformly Ultimate Boundedness

This paper investigates a tracking problem for flexible air-breathing hypersonic vehicles (FAHVs) with composite disturbance. The composite disturbance produced by flexible effects, parameter uncertainties, and external interferences is modeled as a kind of unknown derivative-bounded disturbance in this paper. Then a novel composite control strategy is presented for the nonlinear FAHV model with the composite disturbance, which combines a nonlinear disturbance-observer-based compensator (NDOBC) and a dynamic-inversion-based sliding mode controller (DIBSMC). Specifically, the NDOBC is constructed to estimate and compensate for the composite disturbance, and the DIBSMC is designed to track desired trajectories of velocity and flight path angle. Moreover, the uniformly ultimate boundedness of the composite system can be guaranteed by using Lyapunov theory. Finally, simulation results on a full nonlinear model of FAHVs demonstrate that the proposed nonlinear disturbance-observer-based sliding mode controller is more effective than the traditional DIBSMC. Specifically, it is shown that the chattering of traditional DIBSMC in presence of composite disturbances can be attenuated with the NDOBC.

Adaptive fuzzy backstepping control of underactuated multi-cable parallel suspension system with tension constraint

2021 ◽  
pp. 014233122098594
Author(s):  
Naige Wang ◽  
Guohua Cao
Keyword(s):  
Disturbance Observer ◽  
Reference Model ◽  
Rapid Development ◽  
Backstepping Control ◽  
Suspension System ◽  
Theoretical Modelling ◽  
Parameter Uncertainties ◽  
Nonlinear Disturbance Observer ◽  
Adaptive Fuzzy ◽  
Nonlinear Disturbance

Multi-cable parallel suspension system (MCPSS) is designed to lift a heavy object with rapid development of deep resources exploitation. An adaptive fuzzy backstepping control strategy combining with nonlinear disturbance observer is studied to synthetically control the posture for the underactuated MCPSS with tension constraint in this article. Firstly, a theoretical modelling of the MCPSS with boundary constraints is derived by the extended Hamilton’s Principle. Secondly, the parameter uncertainties and time-varying disturbances are compensated by the fuzzy system and nonlinear disturbance observer, respectively. Thirdly, an adaptive fuzzy backstepping feedback controller based on the reference model is proposed to suppress vibration and control posture of the suspension platform. Finally, an Automatic Dynamic Analysis of Mechanical Systems (ADAMS) simulation and a numerical calculation are used to illustrate the theoretical model and the proposed control performance.

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