Conventional Active Disturbance Rejection Control Research Articles

On improved active disturbance rejection controller design for a pumped storage hydro unit

The pumped storage hydro unit (PSHU) shows bad dynamic performance because of the frequent switching of working conditions and the S-shaped characteristics of pump turbine. This paper proposes an improved fixed-time active disturbance rejection controller to improve the control performances and counteract the influences of uncertainties including modeling error and friction. A disturbance observer is designed to estimate the total uncertainty by using the information of the states and outputs, compensating the adverse effects of the total uncertainty actively by feed-forward principle as a result. The outstanding benefit of the disturbance observer lies in that it can be designed separately from the original controller and can enhance the performances of the PSHU without changing the original controller. Simulation results show that comparing with the conventional active disturbance rejection controller, the improved active disturbance rejection controller has better adaptability and higher robustness towards the system load disturbance, and the dynamic performance of the system is improved.

Speed Tracking and Anti-Slip Control for Heavy Freight Trains Considering the Conicity of the Wheel

To ensure the safe and punctual transportation of freight trains, it is crucial for the train to travel at the targeted speed on the track. This paper proposes a scheme for speed tracking and anti-slip control for freight trains. The speed tracking is implemented through predictive auto disturbance rejection control (PADRC), which includes a flexible Smith estimation module capable of accurately predicting the output of large time delay systems, such as freight trains. The key to anti-slip control relies on the precise observation of the radial velocity and slip rate. Therefore, an unscented Kalman filter observer is designed in this article, incorporating an adaptive parameter adjustment mechanism to enhance observation accuracy. The anti-slip parameters obtained from this observer can then be used to determine the anti-slip control scheme. The effectiveness of this scheme is demonstrated through simulations of the HXD1 electric traction locomotive’s driving process, using line data from the Geku line section in China. Compared to conventional active disturbance rejection control, PADRC reduces speed fluctuation by 55%, and freight trains under anti-slip control decrease the slip speed by 90%.

Input channel gain adaptive active disturbance rejection control based on robust adaptive finite‐time parameter estimation

AbstractThis paper presents a novel input channel gain adaptive active disturbance rejection control (ICGA‐ADRC) framework for the nonlinear control system with large load variation. This paper first introduces the design of ICGA‐ADRC and proves its stability through the rigorous Lyapunov approach. Subsequently, the proposed controller is simulated by subjecting it to a nonlinear mass‐spring‐damping system characterized by significant load variations. Furthermore, the position‐tracking performance of the controller is tested experimentally by using a motor‐driven pendulum system with various loads. Finally, the results of both simulations and experiments show that the ICGA‐ADRC is capable of compensating for system model uncertainty and external perturbation while accurately estimating the system input channel gain in real‐time. The innovation of this paper is that the robustness of active disturbance rejection control (ADRC) to the system load variation is significantly strengthened by integrating robust adaptive finite‐time parameter estimation method into the conventional ADRC control architecture.

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.

Two-Axis Optoelectronic Stabilized Platform Based on Active Disturbance Rejection Controller with LuGre Friction Model

To realize the stable tracking control of the optoelectronic stabilized platform system under nonlinear friction and external disturbance, an active disturbance rejection controller (ADRC) with friction compensation is proposed to improve the target tracking ability and anti-disturbance performance. First, a nonlinear LuGre observer is designed to estimate friction behavior and preliminarily suppress the interference of friction torque on the system. Then, an ADRC is introduced to further suppress the residual disturbance after friction compensation, and the stability of the ADRC system is also proved. The effectiveness of this scheme is proved by simulation experiments, and this scheme is compared with conventional ADRC and LuGre friction feedforward compensation. The simulation results show that an ADRC with LuGre friction compensation is better with trajectory tracking performance, which suppresses the influence of disturbance and improves the stability of the optoelectronic stabilized platform system.

A New Approach to Nonlinear State Observation for Affine Control Dynamical Systems

In this work, a Nonlinear Higher Order Extended State Observer (NHOESO) is presented to replace the Linear Extended State Observer (LESO) used in Conventional Active Disturbance Rejection Control (C-ADRC) solutions. In the NHOESO, the standard LESO is completed with a two-term smooth nonlinear function with saturation-like characteristics. The proposed novel NHOESO enables precise observation of the generalized disturbances with higher-order derivatives. The stability of the NHOESO is examined with the aid of the Lyapunov method. A simulation of an uncertain nonlinear Single-Input–Single-Output (SISO) system with time-varying external disturbances confirms that the proposed NHOESO copes well with the generalized disturbance, which is not true for other ESOs.

A Novel ADRC Control Strategy for PWM Rectifier

Aiming at current harmonics, disturbance immunity and energy efficiency of pulse width modulation (PWM) rectifier system, a novel active disturbance rejection control (ADRC) strategy based on equivalent input disturbance (EID) is proposed. The circuit equations of the system are established, and then the underactuated characteristics of the model are used to design a dual closed-loop control strategy. Based on the conventional ADRC voltage loop controller, a new nonlinear error state feedback function is constructed by using the error estimation of the EID control to design a improved ADRC control strategy. The current loop adopts sliding mode controller. Simulation models are built by Matlab/Simulink, and conducted comparative tests. The results demonstrate that the novel ADRC control strategy has better performance than the traditional ADRC control strategy, faster DC voltage response rate, higher power factor and better results in resisting voltage disturbance and load disturbance.

Automatic Current-Constrained Double Loop ADRC for Electro-Hydrostatic Actuator Based on Singular Perturbation Theory

For an electro-hydrostatic actuator (EHA), the position, speed, and current cascade three-loop control architecture are dominant in existing active disturbance rejection control (ADRC). However, this architecture suffers from many problems, such as severe noise sensitivity of the extended state observer (ESO), excessive complexity of control structure, and too many tuned parameters, which makes the controller not easy to implement in practice. Aiming at the above drawbacks, a novel cascade double-loop ADRC strategy that is automatic current-constrained is proposed, which makes the whole ADRC architecture simplified to the position and the integrated speed–current double-loop architecture. Firstly, for the position control loop, the singular perturbation theory is used to reasonably reduce the order of the model for the position subsystem of EHA. A reduced order ADRC controller (ROADRC) is synthesized, which not only effectively reduces the noise sensitivity of ESO, but also circumvents use of the actuation acceleration information in the controller design process. Secondly, the integrated speed–current ADRC controller is designed by taking the speed and current subsystems of EHA into synthesis, which avoids the problem of excessive current loop bandwidth in conventional three-loop control architecture, and the number of tuned parameters is significantly reduced. Additionally, an uncomplicated and effective automatic current-constrained ADRC controller (CACADRC) is designed to solve the problem in the integrated speed–current ADRC that the current cannot be automatically constrained. Finally, by comparing the three-loop PI controller with the traditional three-loop ADRC, a detailed simulation analysis is carried out to verify the effectiveness and merits of the proposed controller. The simulation results show that the proposed controller not only inherits the advantages of high precision and strong disturbance rejection performance of the conventional ADRC, but can also efficiently decrease the noise sensitivity of ESO and effectively achieve the current-constrained control.

Fractional proportional derivative-based active disturbance rejection control of knee exoskeleton device for rehabilitation care

The use of rehabilitation exoskeleton by physiotherapists in their daily practice is becoming more common. In this study, the active disturbance rejection controller (ADRC) is proposed to ensure high performance of trajectory tracking for asstitve exoskeleton at the level of knee-joint. The controlled medical robot has to mimic the actual physical training and application for knee-rehabilitation. Two versions of ADRC is presented to control the rehabilitation system. One version is based on conventional ADRC, while the other version is based on fractional proportional-derivative PD-ADRC. A comparison study in performance has been conducted between two versions of ADRCs in terms of robustness against disturbances. According to numerical simulations, the results showed that the fractional PD-based ADRC ouptperforms the ADRC in terms of robustness characteritics based on the index root mean square error (RMSE).

Active disturbance rejection control for optoelectronic stabilized platform based on model-assisted double extended state observers

PurposeThis study aims to promote the anti-disturbance and tracking accuracy of optoelectronic stabilized platforms, which ensure that optical detectors accurately track targets and acquire high-quality images.Design/methodology/approachAn improved active disturbance rejection control (ADRC) strategy based on model-assisted double extended state observers (MDESOs) is proposed in this paper. First, by establishing an auxiliary model, the total disturbances are separated into two parts: inner and external disturbances. Then, MDESOs are designed to estimate the two parts by separately using two parallel ESOs, by which the controlled plant is adjusted to the ideal pure integral series. Simultaneously, combined with the nonlinear state error feedback, an overall control strategy is established.FindingsCompared with the conventional ADRC and proportional derivative, the improved ADRC (IADRC) has stronger robustness and adaptability and effectively reduces the requirements for model accuracy and the gain of the ESO. The error of the auxiliary model is tolerated to exceed 50%, and the parameter values of the MDESOs are reduced by 90%.Originality/valueThe total disturbance rejection rate of the proposed strategy is only 3.11% under multiple disturbances, which indicates that the IADRC strategy significantly promotes anti-disturbance performance.

Combined feedforward and error-based active disturbance rejection control for diesel particulate filter thermal regeneration

In this paper, a novel control solution, which combines a feedforward control law and an error-based version of the active disturbance rejection control (ADRC) scheme, is proposed for the exhaust gas temperature control during the thermal regeneration process of a diesel particulate filter in the exhaust line of a diesel engine. Attributed to the complexity of the controlled upstream diesel oxidation catalyst (DOC), its thermodynamics is firstly captured and characterized by a set of linear models through identification modeling. Then, a novel error-based ADRC controller, in which the separated components in conventional ADRC such as the extended state observer (ESO) and the feedback compensator are restructured into a single, modularized control function block, is designed by applying the identified nominal DOC model. In order to further unburden the error-based ESO for better achievements, a combined feedforward compensator is well designed on the basis of the principle of energy balance. Thus a hybrid, 2-degree-of-freedom (2-DOF) controller is developed for better dynamic performance of the controlled DOC system. Its stability performance is also analyzed in the work. The robustness and advantages of the presented hybrid control scheme are finally validated and compared with a well-tuned regular PID-based controller by means of extensive simulation and experimental tests. The results show that the proposed hybrid controller is capable of providing more accurate and faster temperature response and is less sensitive to the variation of system parameters and external disturbances. Moreover, as the error-based ADRC in the hybrid scheme takes the reference tracking error as its direct input and is compatible with the regular PID controller in terms of input and output interfaces, it herein provides an appealing control scheme for existing applications as a substitute for the conventional PID-based controllers to achieve improved performance.

Complex Coefficient Active Disturbance Rejection Controller for Current Harmonics Suppression of IPMSM Drives

Conventional active disturbance rejection controller (ADRC) for interior permanent magnet synchronous motor (IPMSM) drives suffers deteriorated performance in dealing with low-order harmonic disturbances. To enhance the capability of ADRC in rejecting such disturbances, this article proposes a complex coefficient active disturbance rejection controller (CCF-ADRC). The complex coefficient filter (CCF), which is capable of extracting signals with selective frequency and selective phase sequence from the input orthogonal signals, is incorporated into the extended state observer to enhance its estimation accuracy on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> -axis harmonic disturbances. With the harmonic disturbances accurately estimated, the subsequently designed CCF-ADRC can achieve enhanced performance in rejecting such disturbances. Theoretical analysis on the stability, the harmonics rejection capability, the command tracking capability, and the influence of parameter mismatches are systematically conducted. Comprehensive experiments on a 1.0-kW IPMSM verify the effectiveness of the proposed method.

A Novel Design of Disturbance Compensator in Active Disturbance Rejection Control

This article aims to describe a novel design method of disturbance compensator in ADRC (Active Disturbance Rejection Control) based on Lyapunov stability theory. Error-based state equation is used to simplify the ADRC structure. The state feedback controller is designed using LQ (Linear Quadratic) method based on a linearized model. The generalized ESO (Extended State Observer) estimates the nonlinear part, model uncertainty, and external disturbance regarded as "total disturbance." Based on the estimate of the disturbance, disturbance compensator is designed using Lyapunov stability theory. In conventional ADRC, after estimating the disturbance compensator rejects the disturbance. But in this paper, it was not simply rejected. Instead the estimate of the disturbance is used in compensator design to make the Lyapunov candidate decrease more quickly. Our method allowed improved the convergence rate of ADRC. A numerical example and IWP (Inertia Wheel Pendulum) stabilization simulation confirmed the new method for effectiveness evaluation.

A New Nonlinear Controller for the Maximum Power Point Tracking of Photovoltaic Systems in Micro Grid Applications Based on Modified Anti-Disturbance Compensation

In the photovoltaic system, the performance, efficiency, and generated power of the PV system are affected by changes in the environment, disturbances, and parameter variations, and this leads to a deviation from the operating maximum power point (MPP) of the PV system. Therefore, the main aim of this paper is to ensure the PV system operates at the maximum power point under the influence of exogenous disturbances and uncertainties, i.e., no matter how the irradiation, temperature, and load of the PV system change, by proposing a maximum power point tracking for the photovoltaic system (PV) based on the active disturbance rejection control (ADRC) paradigm. The proposed method provides better performance with excellent tracking for the MPP by controlling the duty cycle of the DC–DC buck converter. Moreover, comparison simulations have been performed between the proposed method and the linear ADRC (LADRC), conventional ADRC, and the improved ADRC (IADRC) to investigate the effectiveness of the proposed method. Finally, the simulation results validated the accuracy of the proposed method in tracking the desired value and disturbance/uncertainty attenuation with excellent response and minimum output performance index (OPI).

Robust tracking for nanopositioning stages using sliding mode control with active disturbance rejection: Design and implementation

This paper presents the design and implementation of a novel sliding mode control integrated with active disturbance rejection (SMCDR) for precise robust trajectory tracking of piezoelectric nanopositioning stages. The model uncertainties, nonlinearity, and external disturbances of the piezoelectric nanopositioning stage are regarded as a lumped disturbance, which is estimated by an extended state observer. The active disturbance rejection control (ADRC) strategy is used to realize a preliminary trajectory tracking, while the sliding mode control is adopted to handle the estimation error and residual uncertainties, and to improve the tracking performance. The exponential stability of the proposed SMCDR is proved using Lyapunov’s direct method. The proposed SMCDR controller combines the strength of both ADRC and sliding mode control, exhibits a simple structure, requires only the position measurements, and does not require any information of model parameters except for an approximate constant gain. Experimental results reveal the robustness of the SMCDR approach in suppressing the hysteresis of piezoelectric actuator, and illustrate the superior performance over conventional ADRC, integral sliding mode controller (ISMC) and PID controller for trajectory tracking control of piezoelectric nanopositioning stages.

Active Disturbance Rejection Control for Delayed Electromagnetic Docking of Spacecraft in Elliptical Orbits

In this article, an active disturbance rejection control (ADRC) scheme is proposed for the electromagnetic docking of spacecraft in the presence of time-varying delay, fault signals, external disturbances, and elliptical eccentricity. By introducing an auxiliary variable, an intermediate observer (IO) is presented to estimate the relative motion information and the total disturbance resulting from fault signals, unknown mass, external disturbances, and elliptical eccentricity. Then, an ADRC scheme is developed to guarantee that the relative position, relative velocity, and the estimation errors of relative motion information and the total disturbance can all converge into the neighborhood of the equilibrium. With the proposed control scheme, the time-delay factor is fully considered in the controller design to avoid adverse effect, and the uniform ultimate boundedness stability of the entire closed-loop system is analyzed with a rigorous theoretical proof. In comparison to conventional ADRC and other state-of-the-art schemes, the proposed ADRC scheme has several advantages, e.g., high accuracy, strong robustness, and requires no prior knowledge of the fault, time-varying delay and states information due to IO-based relative motion information and total disturbance estimations. Finally, numerical simulations are performed to show the effectiveness of the proposed control scheme.

Enhanced Active Disturbance Rejection Current Controller for Permanent Magnet Synchronous Machines Operated at Low Sampling Time Ratio

Recently, active disturbance rejection control (ADRC) scheme has been widely used for current regulation in ac drive systems owing to its robustness to system uncertainties and its high disturbance-rejection capability. However, it has not been considered as an option for high-speed drives usually operated at limited switching and sampling frequencies. Therefore, this article thoroughly analyzes and discusses the effects of high operating speed, modulation, and computational delays on the conventional ADRC. Based on this analysis, an enhanced ADRC for the current control is proposed to operate the drive system at low sampling time ratio with high robustness to the internal and external disturbances. Effect of model uncertainties on the proposed scheme has also been analytically analyzed and reported. Comprehensive simulation and experimental results have been presented to demonstrate the improved performance of the proposed ADRC scheme and to support the analytical studies.

Optimized trajectory tracking control of the clearance manipulator based on improved PSO algorithm

Aiming at the problems of low joint trajectory tracking accuracy and poor anti-interference ability caused by parameter uncertainty, nonlinearity, and external interference in the hydraulic servo system of the clearance manipulator, an active disturbance rejection servo control method optimized based on the improved Particle Swarm Optimization algorithm is proposed. First, through the kinematic and dynamic analysis of the clearance manipulator, the general solutions of its forward and inverse kinematics are derived, and the relationship expression between each joint angle and the extension of the piston rod of the driving cylinder is obtained according to the relationship between the joint space and the driving mechanism space; Second, the state space differential equations of the hydraulic system of the working device are derived using mechanistic modeling, and this is used to design an active disturbance rejection servo controller for each joint, and the parameters of the active disturbance rejection controller are optimized using an improved PSO algorithm to improve the control performance. Simulation and experimental results show that compared with classical PID control and conventional Active Disturbance Rejection Control, the improved ADRC in this paper has higher trajectory tracking control accuracy and the ability to suppress external disturbances.

Linear Active Disturbance Rejection Controllers for PMSM Speed Regulation System Considering the Speed Filter

In the permanent magnet synchronous motor speed regulation system, the dynamic performance of the conventional active disturbance rejection control (ADRC) system will be deteriorated by using a low bandwidth speed filter. To solve this problem, two ADRC controllers considering the speed measurement noise are proposed in this article. One proposed ADRC system is based on the extended state observer (ESO), the other proposed ADRC system is based on phase-locking loop observer (PLLO). In the proposed two ADRC systems, an integrator is employed as the speed filter so that the measured position can be directly used for observing the speed and disturbance without speed calculation. Meanwhile, by using an integrator as the speed filter, the dynamic performance of the proposed ESO-based ADRC system is not affected since it is independent of the speed filter, and the proposed PLLO-based ADRC system has a better rejection ability for the low-frequency disturbance. Experimental results validate the proposed methods.

Anti-Disturbance Compensation-Based Nonlinear Control for a Class of MIMO Uncertain Nonlinear Systems.

Multi-Inputs-Multi-Outputs (MIMO) systems are recognized mainly in industrial applications with both input and state couplings, and uncertainties. The essential principle to deal with such difficulties is to eliminate the input couplings, then estimate the remaining issues in real-time, followed by an elimination process from the input channels. These difficulties are resolved in this research paper, where a decentralized control scheme is suggested using an Improved Active Disturbance Rejection Control (IADRC) configuration. A theoretical analysis using a state-space eigenvalue test followed by numerical simulations on a general uncertain nonlinear highly coupled MIMO system validated the effectiveness of the proposed control scheme in controlling such MIMO systems. Time-domain comparisons with the Conventional Active Disturbance Rejection Control (CADRC)-based decentralizing control scheme are also included.