Disturbance Observer Design Research Articles

Linear Matrix Inequality Based Data-driven Disturbance Observer Design: Application to a Non-Minimum Phase Motion Stage

Linear Matrix Inequality Based Data-driven Disturbance Observer Design: Application to a Non-Minimum Phase Motion Stage

High-Performance Adaptive Attitude Control of Spacecraft With Sliding Mode Disturbance Observer

A new disturbance observer-based control method is presented in this paper to address the attitude tracking problem of rigid-body spacecraft in the presence of external disturbances and parameter uncertainties. Particularly, a sliding mode disturbance observer (SMDO) is designed. The most important feature of this SMDO is the relaxation of the assumption that external disturbances must be constants or changing at a slow rate, which is a typical assumption required in these classes of problems concerning disturbance observer (DO) design but hard to guarantee from the standpoint of practical engineering. In addition, a special adaptive integral sliding mode controller is combined with the SMDO to ensure system state convergence. The proposed control scheme’s primary advantage is the enhanced robustness against system parameter uncertainties and external disturbances. Stringent closed-loop system stability analysis is performed using Lyapunov-based stability theory. Numerical simulations are carried out on nonlinear model of spacecraft to validate the proposed control scheme’s efficiency compared to the existing methods in the literature.

Design and implementation of a sliding-mode disturbance observer for robotic manipulators with unbalanced rotating payloads

Design and implementation of a sliding-mode disturbance observer for robotic manipulators with unbalanced rotating payloads

Performance Evaluation of Different Control Methods for an Underactuated Quadrotor Unmanned Aerial Vehicle (QUAV) with Position Estimator and Disturbance Observer

The main aim of this manuscript is to design and demonstrate the performance of different control algorithms with position estimator and disturbance observer to track the helical trajectory by an underactuated quadrotor craft under the influence of unmodelled dynamic factors and external disturbances. The manuscript consists of the derivations related to the kinematics and dynamics of quadrotor dully derived using the Newton Euler approach. It is one of the strenuous tasks to stabilize and control the quadrotor for helical trajectory tracking since it is an underactuated mechatronic system. In addition to this, with inclusion of unmodelled dynamic factors, it faces some of the serious transient and steady-state issues including Zeno noise. In this research manuscript, dual-loop single-dimension fuzzy sliding mode control (DLSDF-SMC) is proposed to improve the helical trajectory tracking performance, and to tackle the unmodelled dynamic factors, a state feedback controller is proposed consisting of a position estimator and disturbance observer design. The entire system is distributed into two subsystems such that within the angular subsystem, the attitude control is proposed using DLSDF-SMC, and for the translational subsystem, the paper proposes the position control design based on the hyperbolic function to avoid the gimbal lock issue. The overall stability of the proposed closed-loop control scheme is also proved. The simulation work for the proposed algorithm is performed using MATLAB and Simulink software and compared with the conventional sliding mode control (SMC) and fuzzy-based SMC control designs. This work demonstrates that the DLSDF-SMC control technique with position estimator and disturbance observer design in feedback not only improves the aggressive maneuvers while tracking the helical trajectory but also tackles the transient and steady-state issues.

Robust Synchronization Control of Uncertain Fractional-Order Chaotic Systems via Disturbance Observer

This paper studies the synchronization of two different fractional-order chaotic systems through the fractional-order control method, which can ensure that the synchronization error converges to a sufficiently small compact set. Afterwards, the disturbance observer of the synchronization control scheme based on adaptive parameters is designed to predict unknown disturbances. The Lyapunov function method is used to verify the appropriateness of the disturbance observer design and the convergence of the synchronization error, and then the feasibility of the control scheme is obtained. Finally, our simulation studies verify and clarify the proposed method.

Design of Composite Disturbance Observer and Continuous Terminal Sliding Mode Control for Piezoelectric Nanopositioning Stage

The nonlinearities of piezoelectric actuators and external disturbances of the piezoelectric nanopositioning stage impose great, undesirable influences on the positioning accuracy of nanopositioning stage systems. This paper considers nonlinearities and external disturbances as a lumped disturbance and designs a composite control strategy for the piezoelectric nanopositioning stage to realize ultra-high precision motion control. The proposed strategy contains a composite disturbance observer and a continuous terminal sliding mode controller. The composite disturbance observer can estimate both periodic and aperiodic disturbances so that the composite control strategy can deal with the disturbances with high accuracy. Meanwhile, the continuous terminal sliding mode control is employed to eliminate the chattering phenomenon and speed up the convergence rate. The simulation and experiment results show that the composite control strategy achieves accurate estimation of different forms of disturbances and excellent tracking performance.

Output-Feedback Speed-Tracking Control Without Current Feedback for BLDCMs Based on Active-Damping and Invariant Surface Approach

With the proposed technique, a controlled brushless DC motor can robustly track the desired trajectory, while estimating angular acceleration, to remove current feedback. The controller design task does not require true motor parameters and load information using the standard disturbance observer design approach. The first feature is that a parameter-independent angular acceleration observer is devised to avoid direct differentiation of the speed measurement. The second one is that active-damping pole-zero cancellation control stabilizes the surface, thereby describing the desired first-order tracking system dynamics. The prototype 50-W BLDCM control system experimentally evaluates the speed-tracking and positioning performances.

Fuzzy Disturbance Observer Design for a Class of Nonlinear SISO Systems

Fuzzy Disturbance Observer Design for a Class of Nonlinear SISO Systems

Novel Iterative Disturbance Observer Design for a Two-Level Voltage Source Inverter with a Nonlinear Load

Novel Iterative Disturbance Observer Design for a Two-Level Voltage Source Inverter with a Nonlinear Load

Design of super twisting disturbance observer based control for autonomous underwater vehicle

Autonomous underwater vehicles (AUVs) operates in uncertain oceanic environment with unknown external non-vanishing disturbances such as ocean currents. To handle such uncertainties, a super twisting algorithm as a disturbance observer based sliding mode controller (STA-SMC) is designed for trajectory tracking of a linearised steering and diving plane models of highly non-linear model of AUV. The efficacy of designed control scheme has been verified by comparing it with uncertainty and disturbance estimator (UDE) and disturbance observer (DO) based sliding mode control strategies. The extensive numerical simulations have been performed to demonstrate the robustness of the proposed scheme. It is found that the proposed STA-SMC scheme is not only effective in compensating the uncertainties in hydrodynamic parameters of the vehicle but also it rejects unpredictable disturbances due to fast and high magnitude underwater ocean currents. The stability of the designed observer based control scheme is provided by Lyapunov theory.

Neuroadaptive control of saturated nonlinear systems with disturbance compensation

Extended state observer acting as a popular tool can estimate the system states and total disturbances simultaneously. However, for extended-state-observer-based control of high-order nonlinear systems, there are still some difficult issues to solve, such as how to simultaneously reject matched and mismatched model uncertainties with strict theoretical proof, especially in the case of output feedback, “explosion of complexity” and so on. Motivated by these reasons, different control schemes in full-state feedback and output feedback conditions respectively will be integrated via the filter-based backstepping approach for saturated nonlinear systems. For the full-state feedback condition, adaptive neural network and extended state observer will be combined for each dynamic to handle the unknown nonlinear dynamics and external disturbances, respectively. For the output feedback condition, nonlinear disturbance observer design will be incorporated into the neural-network-based extended state observer scheme to handle mismatched disturbances at the same time. In particular, an auxiliary system will be constructed to compensate for the saturation influence. Moreover, the anticipate control effects of the developed controllers have been demonstrated by contrastive results for a hydraulic servo system.

Dynamic analysis of the center position control and design of disturbance observers during annealing and pickling

In this study, we propose a new center position controller (CPC) to control the center position error (CPE) of the steel strip during the annealing and pickling processes. The model of the nonlinear CPC system is described for two adjacent rolls and extended to multifeed rolls. We derive a linearized discrete state equation for the multi CPC and analyze its characteristics. A simulator of the CPC system that includes rollers, actuators, and plant data is developed to test the dynamics of the CPC. In addition, a disturbance observer with a low pass filter Q(s) is designed to minimize the effects of various disturbances. The order and time constant of the filter are selected in consideration of the order of the system and the response of the actuator. Results of the offline tests show that the CPE is greatly decreased by the proposed control technology.

Integrated MIMO fault detection and disturbance observer-based control

This paper presents a new method of disturbance observer-based control (DOBC) for multi-input-multi-output (MIMO) highly-coupled unstable systems. In contrast to the current input–output approach for stable single-input-single-output (SISO) systems, the Youla parameterization of stabilizing controllers by full order state observer (FOSO) feedback control is shown more appropriate for general MIMO systems, while retaining the intuitive aspects of DOBC design. We propose a general MIMO DOBC expanded from this single FOSO stabilizing control, where a parallel number of FOSOs for fault detection, state estimation, and disturbance observer are integrated to achieve the relevant operational requirements and performance. Within this integrated control system, we propose a MIMO disturbance observer design method by a game-theoretic detection filter (GTDF) design. The DOBC design features GTDF disturbance decoupling followed by H-infinity model matching to establish the desired bandwidth for each channel of the decoupled disturbance observer. The proposed DOBC is applied to an open-loop unstable MIMO Active Magnetic Bearing Spindle (AMBS). Experimental results are presented to demonstrate the design method and control performance.

Cooperative output regulation for a network of parabolic systems with varying parameters

This paper is concerned with the cooperative output regulation problem for a network of agents with different dynamics described by parabolic PDEs subject to spatially- and time-varying parameters. Firstly, a networked controller is designed achieving output synchronization for identical finite-dimensional reference models, which deliver the state of the global reference model required for the synchronization to the parabolic agents. The latter can be subject to local disturbances acting in-domain, on all boundaries and on the anti-collocated output to be controlled. The cooperative output regulation problem is solved by designing local output feedback regulators for the parabolic agents. This requires the solution of time-varying regulator equations and the design of disturbance observers for parabolic systems with spatially- and time-varying coefficients. For this, a systematic backstepping approach is provided and it is shown that cooperative output regulation with exponential convergence is ensured for the resulting multi-agent system. The results of the paper are applied to the cooperative output regulation of a heterogeneous network of four parabolic agents in the presence of local disturbances.

Variable Forgetting Factor-Based Adaptive Kalman Filter With Disturbance Estimation Considering Observation Noise Reduction

This paper addresses the influence reduction of quantization and observation noises in a disturbance observer (DOB) technique. DOB is a disturbance estimation method that makes control systems robust. However, in implementing low-resolution sensors, disturbance estimates from DOB are considerably influenced by observation and quantization noises. In this paper, a novel DOB design method for simultaneous estimation of state and unknown disturbances, including the reduction of noise influences, is proposed. The proposed method is divided into two components. The first component is a Kalman filter (KF)-based DOB for simultaneous estimation of state and unknown disturbances. To improve the estimation performance through the KF-based DOB, a forgetting factor-based adaptive KF (FAKF) was employed. The second component is an adaptive law for the forgetting factor in the FAKF. The adaptive law is used for balancing the estimation accuracy and observation noise reduction. Simulation results involving various types of noise environments demonstrate the effectiveness of the proposed method.

Velocity-sensorless proportional–derivative trajectory tracking control with active damping for quadcopters

The proposed observer-based control mechanism solves the trajectory tracking problem in the presence of external disturbances with the reduction in sensor numbers. This systematically considers the quadcopter nonlinear dynamics and parameter and load variations by adopting the standard controller design approach based on a disturbance observer (DOB). The first feature is designing first-order observers for estimating the velocity and angular velocity error, with their parameter independence obtained from the DOB design technique. As the second feature, the resultant velocity observer-based control action including active damping and DOBs secures first-order tracking behavior for the position and attitude (angle) loops through pole zero cancellation, thereby forming a proportional–derivative control structure. Closed-loop analysis results reveal the performance recovery and steady-state error removal properties in the absence of tracking error integrators. The numerical verification confirms the effectiveness of the proposed mechanism using MATLAB/Simulink.

Design of disturbance observer based on adaptive‐neural control for large‐scale time‐delay systems in the presence of actuator fault and unknown dead zone

SummaryThis article presents an adaptive neural compensation scheme for a class of large‐scale time delay nonlinear systems in the presence of unknown dead zone, external disturbances, and actuator faults. In this article, the quadratic Lyapunov–Krasovskii functionals are introduced to tackle the system delays. The unknown functions of the system are estimated by using radial basis function neural networks. Furthermore, a disturbance observer is developed to approximate the external disturbances. The proposed adaptive neural compensation control method is constructed by utilizing a backstepping technique. The boundedness of all the closed‐loop signals is guaranteed via Lyapunov analysis and the tracking errors are proved to converge to a small neighborhood of the origin. Simulation results are provided to illustrate the effectiveness of the proposed control approach.

Design and Evaluation of State and Disturbance Observers for a Multivariable Magnetic Levitation System

For inherently unstable magnetic levitation (maglev) systems, state observation is required for feedback control, and disturbance estimation is needed to compensate for unknown disturbances. Previous designs for simultaneously observing state and disturbance can lead to aggressive disturbance compensation and an unstable levitation. Aiming at these problems, this paper presents a state and disturbance observer that has a cascade structure for a maglev system. The proposed design allows the dynamics of disturbance observation to be separately tuned from those of state observation, avoiding aggressive disturbance compensation and enabling a stable levitation of a maglev system. In this paper, the proposed and previous state and disturbance observers are designed and realized for a maglev system that features wide ranges of translation and rotation motions in five directions. Comparative studies are reported in this paper, and experimental results show feasibility and efficiency of the proposed scheme.

New Disturbance Observer Design and Application on the Electro-Optical Stabilized Platforms

Aiming at modeling difficulty of the random and time-varying disturbance on the Electro-Optical Stabilized Platforms (EOSPs), a control algorithm of perturbation rejecter + Disturbance Observer (DOB) is proposed by combining the advantage of the rejecter and observer, to improve the robust performance of whole control system and the performance of disturbance suppression. The above control methods are validated in dual-rate loop structure under different friction load and effectively improve the stabilize accuracy of EOSPs. The results show that the compensation strategies of coordinating with one another can constrain effectively the impact of control performance caused by disturbance and load change, and improve the platforms’ stabilization accuracy. According to experimental verification, the control method is effective and applicable in different load conditions, and can provide reference resources and basis for engineering application of the control algorithm.

Adaptive composite neural network disturbance observer-based dynamic surface control for electrically driven robotic manipulators

This paper presents an adaptive backstepping control scheme for electrically driven robotic manipulator (EDRM) system with uncertainties and external disturbances by using neural network disturbance observer (NNDO) and dynamic surface control (DSC) design technique. NNDO is employed to estimate the uncertainties and external disturbances such that the priori information of the unknown dynamics will not be needed. To overcome the problem of “explosion of complexity” inherent in the backstepping design method, the DSC technique is integrated into the adaptive backstepping control design framework, where the NNDOs with adaptive composite law are utilized to compensate the uncertainties and external disturbances of EDRM. Based on the Lyapunov stability theory, it can be proven that the closed-loop system is stable in the sense that all the variables are guaranteed to be uniformly ultimately bounded. The results of simulation and experimental tests demonstrate the approximation capability of NNDO and the effectiveness of the proposed adaptive DSC scheme.