Disturbance Rejection Ability Research Articles

Adaptive Robust Control of an Industrial Motor-Driven Stage with Disturbance Rejection Ability Based on Multidimensional Taylor Network

Linear motors are widely used in practical engineering fields, but it is difficult to achieve accurate position control because of model uncertainty, external interference, input nonlinearity and other factors. In this paper, a multidimensional Taylor network (MTN) controller with flexible learning robustness is proposed to realize tracking control and make the motor have excellent antijamming ability. The controller is composed of a robust feedback part, a parameter adaptive part and a multidimensional Taylor network control part. This strategy has good track tracking performance and anti-interference ability. In this control strategy, the input of the multidimensional Taylor network is determined only by the referable trajectories, and no model information is required. In addition, the designed multidimensional Taylor network can accurately describe the relationship between state variables and any complex disturbance, which is the basis of disturbance suppression. Finally, the stability of the controller is proved by the Lyapunov theorem. The unknown interference comparison experiment and numerical simulation experiment are carried out on the industrial linear motor platform, respectively. Experimental results show that compared with NNPID, the proposed algorithm has smaller overshoot and better performance under various error statistical dimensions.

Disturbance Observer-Based Event-Triggered Adaptive Command Filtered Backstepping Control for Fractional-Order Nonlinear Systems and Its Application

This paper considers the disturbance observer-based event-triggered adaptive fuzzy tracking control issue for a class of fractional-order nonlinear systems (FONSs) with quantized signals and unknown disturbances. To improve the disturbance rejection ability, a fractional-order nonlinear disturbance observer (FONDO) is designed to estimate the unknown composite disturbances. Furthermore, by combining an improved fractional-order command-filtered backstepping control technique and an event-triggered control mechanism, an event-triggered adaptive fuzzy quantized control scheme is established, which guarantees the desired tracking performance can be achieved even in the presence of network constraint. Finally, the validity and superiority of the theoretic results are verified by a fractional-order horizontal platform system.

Fixed‐time disturbance observer‐based fixed‐time path following control for small fixed‐wing UAVs under wind disturbances

SummaryIn this paper, the three‐dimensional path following control problem for small‐scale fixed‐wing unmanned aerial vehicles (UAVs) subject to external wind disturbances is investigated. A fixed‐time disturbance observer is designed to estimate the external wind disturbance. The estimates are then incorporated into the fixed‐time integral terminal sliding mode controller such that a composite control scheme is proposed. Under the proposed control scheme, the UAV system not only guarantees a fixed‐time convergence rate but also possesses stronger disturbance rejection ability and better robustness. Finally, the effectiveness of this strategy is verified by numerical simulations.

Periodic Event-Triggered Control for Networked Control Systems With External Disturbance and Input and Output Delays.

This article investigates the problem of periodic event-triggered output-feedback control for networked control systems in the presence of external disturbance and input and output delays. With the aid of the prediction technique, we first develop the predictor-based-extended state observer to reconstruct the system information, including the unknown state and disturbance. The periodic event-triggered output-feedback control law is then designed via the disturbance/uncertainty estimation and attenuation (DUEA) method, such that the communication times can be remarkably reduced and, at the same time, the disturbance rejection ability can be effectively enhanced. Under the predictor-based event-triggered control method, the influence of the time delays is effectively attenuated, and the effect of external disturbance is considerably attenuated due to the prediction technique and the DUEA method. By using the small-gain arguments, this article gives some sufficient stability conditions for the overall control system, and the explicit computations of sampling/updating period and time delays are presented as well. Finally, we employ a practical example and show some comparative simulation results to demonstrate the advantages of the predictor-based event-triggered control method proposed in this article.

A Marine-Predator-Algorithm-Based Optimum FOPID Controller for Enhancing the Stability and Transient Response of Automatic Voltage Regulators

An improved design optimization method for fractional-order-based proportional integral derivative (FOPID) controllers is proposed in this paper to enhance the stability and transient response of automatic voltage-regulator systems. The FOPID represents a higher degree-of-freedom controller through having five tunable parameters, compared with only three parameters in the integer-order PID controller. In the literature, the performance of the FOPID is highly determined through the design method and its parameter-determination process. Recently, optimum design of the FOPID has found wide employment in several engineering applications through using metaheuristic optimization algorithms. In this paper, an improved method for the FOPID’s parameter optimization is proposed for AVR applications using the marine predator optimization algorithm (MPA). The proposed MPA–FOPID controller is verified through comparing its performance with other featured and newly developed optimization algorithms. The proposed MPA–FOPID comparative analysis has been proven to have better stability, frequency response, robustness, faster response, and disturbance-rejection ability over the other studied methods in this paper.

Compliant Control of Flexible Joint by Dual-Disturbance Observer and Predictive Feedforward

The compliant control of a flexible joint relies on the accurate external torque information and effective internal disturbance compensation. To achieve this, most of the prior works use a built-in torque sensor and a lumped disturbance observer based on a single encoder. This increases the weight and cost of the system. In this article, a novel dual-disturbance observer (DDOB) based on the encoder feedbacks from both the motor and link sides is proposed so that the friction and external torque are estimated and compensated separately without the torque sensor. Thereby, a feedforward–feedback–DDOB composite scheme is formed for position control. The modified reference sensitivity of this scheme suggests that better tracking accuracy and disturbance rejection ability are achieved. In addition, the estimated external torque is used to alternate the reference trajectory with the given admittance model. To ensure that the feedforward control is realizable, the prediction of the alternated trajectory is done by the online fitting of a polynomial. The output turbulence caused by prediction errors is effectively suppressed by a single deadbeat compensator with the most ancient prediction in memory, while other predictions are weighted by the time-varying ratios. Simulations and real-time experiments are performed to demonstrate the practical appeal of the proposed method.

Optimal tuning of the novel voltage regulation controller considering the real model of the automatic voltage regulation system

This paper deals with the optimal tuning of the controller for the real automatic voltage regulation (AVR) system of the synchronous generator (SG). For this purpose, firstly, a novel proportional-integral controller with two degrees of freedom and anti-windup protection for application in the AVR system is proposed. Secondly, in order to determine the optimal parameters of such a controller, the objective function which takes into account transient response characteristics, disturbance, and measurement noise rejection capabilities of the AVR system is presented. Furthermore, the adaptive modification of the existing metaheuristic African vultures optimization algorithm (AVOA) is introduced for controller parameters design. Finally, unlike the many existing papers in the available literature which use a simplified model of the AVR system, in this work the simulation model of the AVR system is realized by observing the technical documentation of the excitation system of the 40 MVA SG from a hydropower plant Perucica in Montenegro. The results obtained in this work have proven that the proposed AVR controller has superior performances compared with other frequently used controllers in real power plants, in terms of providing transient response quality of the SG terminal voltage, disturbance rejection, and measurement noise mitigation abilities. Additionally, increased convergence speed and improved criterion function value demonstrated that the proposed adaptive modification of the AVOA algorithm outperforms some of the most popular metaheuristic algorithms.© 2017 Elsevier Inc. All rights reserved.

A Sage-Husa Prediction Algorithm-Based Approach for Correcting the Hall Sensor Position in DC Brushless Motors.

Accurate knowledge of the rotor position is essential for the control of brushless DC motors (BLDCM). Any deviation in this identification can cause fluctuations in motor current and torque, increase noise, and lead to reduced motor efficiency. This paper focused on a BLDCM equipped with a three-phase binary Hall sensor. Based on the principle of minimum deviation, this paper estimated the relative installation offset between the Hall sensors. It also provided a clear method for ideal phase commutation position recognition and eliminated the Hall sensor installation position deviation. The proposed pre-calibration method identified and eliminated the offset of the permanent magnet poles, the delay time caused by the Hall signal conditioning circuit, and the offset of the sensor signal identification due to armature response under different loads. Based on the pre-calibration results, a correction strategy for correcting the rotor position information of BLDCMs was proposed. This paper presented a self-adaptive position information prediction algorithm based on the Sage-Husa method. This filters out rotor position information deviations that are not eliminated in pre-calibration. Experimental results on a hydrogen circulation pump motor showed that, after the pre-calibration method was adopted, the Mean Square Error (MSE) of motor speed fluctuations decreased by 92.0%, motor vibration was significantly reduced, average phase current decreased by 62.8%, and the efficiency of the hydrogen circulation pump system was significantly improved. Compared to the traditional KF prediction algorithm, the Sage-Husa adaptive position information prediction algorithm reduced the speed fluctuation during the uniform speed operation stage and speed adjustment stage, the speed curve overshoot, and the commutation time deviation throughout the process by 44.8%, 56.0%, 54.9%, and 14.7%, respectively. This indicates a higher disturbance rejection ability and a more accurate and stable prediction of the commutation moment.

Design of the electric vehicle powertrain systems based on μ-analysis

Aiming at the oscillation in the electric vehicle powertrain systems, a control strategy based on the structural singular value [Formula: see text] is proposed. To solve the problem of robustness under parameter uncertainty, the traditional [Formula: see text]-synthesis needs to obtain all-pass characteristics through the weight function in the nominal system, which reduces the perturbation suppression ability of the system. Unlike the previous use of [Formula: see text]-analysis as a system performance criterion, this paper starts from the essence of parameter uncertainty problems and designs controllers based on the relationship between parameter uncertainty and nominal systems, using structural singular value [Formula: see text] as a performance constraint. The result shows that the [Formula: see text]-analysis not only takes into account the robustness and disturbance rejection ability but also reduces the controller order. In addition, the oscillation suppression effect in the presence of transmission backlash is verified, and the [Formula: see text]-analysis can suppress the oscillation better than the [Formula: see text]-synthesis.

Equivalent-input-disturbance rejection-based adaptive motion control for pneumatic artificial muscle arms via hysteresis compensation models

With outstanding flexibility, pneumatic artificial muscles (PAMs) have shown unique advantages in human–robot interaction environments. However, asymmetric hysteresis nonlinearities, unknown transient or persistent time-varying disturbances, etc., seriously degrade control performance/robustness of PAM arms, and increase actuation failure risks. Meanwhile, existing disturbance rejection methods either rarely handle matched/unmatched disturbances, or require known disturbance dynamics. These defects limit the disturbance rejection ability in practical applications. To this end, a new adaptive output feedback control method is proposed in this article, which achieves efficient positioning and tracking control of PAM arms. Without requiring a priori knowledge of inverse plant models and disturbance upper bounds, the proposed method further enhances robustness against uncertainties and disturbances. Specifically, a generalized Bouc–Wen hysteresis loop is used to describe the asymmetric dynamic force of PAMs. Also, a new adaptive law is designed to compensate for the linearized parameters online. In particular, by applying a modified state observer to derive the equivalent-input-disturbance estimation solution, this article firstly realizes state observation, parameter estimation, and unknown transient/persistent external disturbance rejection simultaneously. The rigorous stability analysis demonstrates that the tracking errors converge to small neighborhoods of the origins. Finally, hardware experimental results with comparisons validate the effectiveness and robustness superiority of the proposed method.

Car‐following strategy of intelligent connected vehicle using extended disturbance observer adjusted by reinforcement learning

AbstractDisturbance observer‐based control method has achieved good results in the car‐following scenario of intelligent and connected vehicle (ICV). However, the gain of conventional extended disturbance observer (EDO)‐based control method is usually set manually rather than adjusted adaptively according to real time traffic conditions, thus declining the car‐following performance. To solve this problem, a car‐following strategy of ICV using EDO adjusted by reinforcement learning is proposed. Different from the conventional method, the gain of proposed strategy can be adjusted by reinforcement learning to improve its estimation accuracy. Since the “equivalent disturbance” can be compensated by EDO to a great extent, the disturbance rejection ability of the car‐following method will be improved significantly. Both Lyapunov approach and numerical simulations are carried out to verify the effectiveness of the proposed method.

Linear Active Disturbance Rejection Control for Dual-Stator Winding Induction Generator AC Power System

In this article, a control strategy based on linear active disturbance rejection control (LADRC) is proposed for the dual-stator winding induction generator (DWIG) ac power system, in order to solve the problems of contradiction between tracking ability and dynamic performance with proportional-integral controller. Based on the rotor-flux-oriented coordinate system, the dynamic mathematic model of the output ac voltage of power winding (PW) is established. The load disturbance on the PW side and the variation of the system parameters are regarded as the total disturbance, which is observed and compensated by linear extended state observer (LESO) and linear state error feedback (LSEF), respectively. By analyzing the swiftness and disturbance-rejection ability with different bandwidths of LESO, the ac voltage LADRC controller is first designed for DWIG. The stability and performance analysis with different controller parameters is given and the robustness of the proposed controller under the parameter mismatch is investigated. Both simulation and experiments show that the proposed LADRC has a better tracking ability and dynamic performance. Moreover, the proposed LADRC also has strong robustness under the parameter mismatch.

Modified Nonlinear Active Disturbance Rejection Control for PMSM Speed Regulation With Frequency Domain Analysis

Strong robustness and smooth speed are two crucial goals of the high-performance permanent magnet synchronous motor (PMSM) drive systems. Conventional active disturbance rejection control (ADRC) strategy generally increases the bandwidth of the extended state observer (ESO) to improve the unsatisfactory disturbance rejection ability, which will inevitably amplify the measurement noise. To address this tough issue, a nonlinear extended state observer (NESO) using finite-time technique is constructed in this paper to enhance the anti-disturbance property. On this basis, the NESO with small bandwidth is sufficient to guarantee strong robustness without sacrificing noise suppression performance. Utilizing the frequency sweep method, the advantages of the proposed NESO based modified ADRC (MADRC) system can be analyzed in terms of frequency domain characteristics, which is more practical than traditional theoretical analysis from a mathematical point of view. Meanwhile, a quasi-resonant (QR) controller is combined with MADRC system to attenuate the main harmonic component of torque ripple for smooth speed. Experimental results are carried out to verify the effectiveness of the proposed control scheme and frequency sweep analysis method.

Composite-disturbance-observer-based backstepping control for three-phase inverters with multiple disturbances

This paper deals with the output voltage tracking control problem of three-phase inverters with multiple disturbances (including parametric perturbations of filter, abrupt disturbances caused by load switching, and harmonic disturbances brought by unbalanced loads and nonlinear loads). Some novel composite disturbance observers are designed to estimate the above multiple disturbances. Based on the disturbance estimates and backstepping control technique, an innovative feedforward-feedback composite tracking control scheme is proposed. The new control scheme has a good disturbance rejection ability and ensures good tracking performances. In the meantime, rigorous stability proof is presented. Simulation and experimental results are illustrated to verify the feasibility and effectiveness of the proposed control scheme.

Modified Flower Pollination Optimization Based Design of Interval Type-2 Fuzzy PID Controller for Rotary Inverted Pendulum System

The Type 2 Fuzzy Logic System (T2FLS) is an enhanced form of the classical Fuzzy Logic System (FLS). The T2FLS based control technics demonstrated a lot of improvements for the past few decades. This is based on the advantage of its membership function (MF). Many experimental studies indicated the superiority of Type 2 Fuzzy Logic Controller (T2FLC) over the ordinary Type 1 Fuzzy Logic Controller (T1FLC), particularly in the event of non-linearities and complex uncertainties. However, the organized design method of T2FLCs is still an interesting problem in the control engineering community. This is due to the difficulties in computing the parameters associated it. A novel application of the Modified Flower Pollination (MFP) optimization algorithm in the design of T2FL is presented. The optimized Cascade Interval Type 2 Fuzzy PID Controller (IT2FPIDC) structure is proposed in this study. The best values of the parameters of the antecedent MFs and the PID gains of IT2FPIDC are found using the MFP algorithm. The MFP optimization technique was used because of its lower computational effort and high convergence speed, in view of the higher number of variables to be optimized in cascaded IT2FPIDC. The MFP-based Type-1 Fuzzy Proportional Integral Derivative Controller (T1FPIDC) is compared with the proposed MFP-based cascade-optimized IT2FPIDC. The rotary inverted pendulum (RIP) which is a non-minimum phase, non-linear, and unstable system is employed as a benchmark for testing the proposed controller. Balance and trajectory-tracking controls of the RIP are considered. Furthermore, the disturbance rejection ability of the proposed controller is analysed. The presented control methos is evaluated on the RIP manufactured by Quanser over many simulations and real-world experiments. The performance characteristics considered are steady state error (Ess), settling time (ts), maximum overshoot (Mp) and rise time (tr). The improvement of the effectiveness and robustness proposed controller in the presence of load disturbance, noise effects and parameter variation is shown.

Disturbance Rejection Control for Networked Control Systems Using Subpredictor-Based Extended State Observer

In this article, we consider the disturbance rejection control problem for networked control systems using a subpredictor-based extended state observer. The networked control system is subject to large input and output delays. To handle the time delays, a subpredictor-based extended state observer is proposed to estimate the unknown state and disturbance by dividing the total delay into small pieces. The proposed observer is composed of a set of predictor-based observers connected in series, and each elementary observer is only responsible for compensating the effect of a fraction of the total delay. By using the disturbance compensation technique, we design a sampled-data composite controller to attenuate the influence of external disturbance. The proposed control method can handle the multirate case where the sensor and controller have different sampling and updating rates. It shows that under the proposed control method, the disturbance rejection ability of the control system can be effectively improved in the presence of arbitrary large input and output delays. The simulation results are given to demonstrate the effectiveness of the proposed control method.

Mismatched Disturbance Compensation Enhanced Robust H$_\infty$ Control for the DC-DC Boost Converter Feeding Constant Power Loads

A new control scheme to enhance the robustness and disturbance rejection ability of a DC-DC boost converter feeding constant power loads (CPLs) is proposed in this paper via introducing mismatched disturbance compensation into the robust H <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\infty}$</tex-math></inline-formula> control. In cascaded DC power converter systems, the load side converters, when tightly controlled, behave as CPLs for their source side converters, where the nonlinearities could result in severe instability. Besides, for power converters in DC microgrids, both the uncertainties/disturbances and the unpredictable load access could result in severe challenges to achieving higher control performance. In particular, the unknown CPLs must be considered as part of disturbances that form the so-called mismatched disturbances. To counteract these negative factors, a practical exact feedback linearization method is used to transform the control problem of a nonlinear system into that of a linear system, and the compensation of mismatched uncertainties/disturbances is introduced into the robust H <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{_\infty}$</tex-math></inline-formula> control design. Moreover, sufficient conditions to ensure the asymptotic stability and robustness of system are established. Both simulation and experimental results confirm the efficiency.

Global Finite-Time Stabilization of Spacecraft Attitude With Disturbances via Continuous Nonlinear Controller

In this paper, a robust continuous controller is investigated to solve the global finite-time attitude stabilization problem of rigid spacecraft system subject to multiple disturbances. The system order is firstly increased by derivation and the derivative of the actual torque is regarded as the virtual control law to be designed. Then, a super-twisting differentiator is constructed to provide finite-time angular acceleration estimations. Finally, based on the estimated angular accelerations, a discontinuous set stabilization control law is designed as the virtual controller. The actual continuous controller is obtained by integrating the discontinuous one. Rigorous proof and stability analysis are presented based on Lyapunov analysis. Compared with most of the existing finite-time control approaches in spacecraft systems, the proposed continuous control scheme guarantees the finite-time set stability of the closed-loop system. Moreover, the system states can converge to the equilibria even in the presence of derivative-bounded disturbances. Simulation studies of the proposed controller are illustrated to demonstrate the strong disturbance rejection ability, fast convergence rate, and high steady-state precision.

Immunity of shunt active power filter based on improved LADRC

To improve the dynamic response speed and performance of active power filter controller, and improve the robustness, tracking ability, and disturbance rejection ability of linear active disturbance rejection controller (ADRC), an improved linear ADRC (LADRC) is proposed. First, a new error adjustment total disturbance is introduced into the linear expansion state observer to adjust the total disturbance of the linear expansion state observer. Then, on the premise of system stability, the controller is applied to the voltage outer loop of shunt active power filter (SAPF), and the mathematical model of active power filter is deduced, and it is controlled according to the first-order linear active disturbance rejection controller. Finally, through frequency domain analysis, the stability, noise immunity, and tracking performance of the improved LADRC are analyzed. Using MATLAB and Simulink simulation platform, the current stability and tracking performance of SAPF under improved LADRC control are simulated and verified, and compared with traditional methods. The simulation results show that the waveform fluctuation of A-phase voltage on the grid side of this method is relatively smooth, and the voltage on the grid side is always kept at ±50 V; the voltage curve of SAPF DC side is kept between the actual set values, about 820 V; the waveform fluctuation of A-phase current on the load side is small, which is ±220 A; the harmonic distortion rate is 4%. It is verified that this method has good tracking effect and anti-interference characteristics, which is of great significance to improve the control performance of active power filter.

A process-model-free method for model predictive control via a reference model-based proportional-integral-derivative controller with application to a thermal power plant

Introduction: Model predictive control (MPC) is an advanced control strategy which can achieve fast reference tracking response and deal with process constraints, time delay and multivariable problems. However, thermal processes in coal-fired power plants are usually difficult to model accurately, which limits the application of MPC to thermal power plants.Methods: To solve the problem, this paper proposes a process-model-free method for MPC via a reference model (RM)-based controller, i.e., a desired dynamic equational (DDE) proportional-integral-derivative (PID) controller (DDE-PID).Results and Discussion: The DDE-PID can provide the design model and enhance the disturbance rejection ability for MPC. Simulations and results of field tests on a coal-fired unit show the superiorities of the proposed controller in reference tracking, disturbance rejection and robustness, which indicates the promising prospect of the field application of the MPC with DDE-PID, or MPC-DDE in short, to thermal power plants.