Active Disturbance Rejection Control Approach Research Articles

Sliding mode active disturbance rejection control for manipulator considering actuator saturation

<p style="text-align: justify;">Considering the issue of low control accuracy in joint trajectory tracking control for manipulator systems with actuator saturation due to external disturbances, modelling inaccuracies, and joint friction, a sliding mode active disturbance rejection control approach was proposed. An improved extended state observer is employed to observe and estimate the lumped disturbances affecting the system, providing feedback compensation. A variable gain reaching law is devised, coupled with a fast non-singular terminal sliding mode to design the system control law, which mitigates chattering inherent and ensuring precision control. Additionally, a novel output error compensation-based anti-windup scheme is introduced to compensate for the detrimental impacts caused by actuator saturation. Simulation results collectively demonstrate that the proposed tracking control algorithm exhibits better control performance and robustness against disturbances.</p>

A fractional‐order active disturbance rejection control for permanent magnet synchronous motor position servo system

AbstractThis paper introduces a novel control scheme for the permanent magnet synchronous motor (PMSM) position servo system using a fractional‐order active disturbance rejection control (ADRC) approach. Specifically, a first‐order ADRC is employed in the current loop, while a fractional‐order ADRC is designed for the position loop. In the latter, a linear extended state observer (LESO) is utilized to estimate and compensate for disturbances, while a fractional‐order proportional derivative (FO[PD]) feedback controller is employed to enhance the control performance. Moreover, a parameter tuning method is presented based on frequency domain specifications. This technique utilizes the flat phase constraint as a design constraint to ensure that the phase is flat near the gain crossover frequency, thus ensuring that the closed‐loop system remains robust to loop gain variations. Simulation and experimental results demonstrate that the proposed fractional‐order ADRC control scheme yields improved dynamic response, disturbance rejection, and robustness to loop gain variations.

Active disturbance rejection control approach to the output tracking of PDEs with general disturbances: A new perspective

In recent years, significant progress has been made in output regulation for systems described by partial differential equations (PDEs) through the active disturbance rejection control approach (ADRC). However, in all these studies, the disturbance typically manifests in a single channel and requires estimation, often necessitating additional measured signals. This is because the disturbance must be identified through the output. In this paper, we approach this problem from a novel perspective: disturbances occur in all channels, yet few measured signals are required. In most cases, only the tracking error is utilized as the measured signal. This marks a significant advancement in the application of ADRC to PDEs. We primarily demonstrate this approach by addressing the output tracking problem for a multi-dimensional heat equation, considering general disturbances across all possible channels. Additionally, we briefly discuss some other one-dimensional problems studied in the literature, such as the one-dimensional wave equation.

The active disturbance rejection control approach to output feedback stabilization of an anti-stable wave equation with corrupted boundary observation

In this paper, we are concerned with the boundary output feedback stabilization for an anti-stable wave equation where the boundary observation is corrupted by a general disturbance. We cope with the disturbance by the approach of active disturbance rejection control. In contrast with the existing results, the assumptions on the derivative of the disturbance are removed. It is necessary to assume that the disturbance is Lipschitz continuous. A state observer together with a disturbance estimator is designed by using the corrupted output. Both the well-posedness and the stability of the closed-loop system are proved. The theoretical results are validated visually by some numerical simulations.

A composite fractional order active disturbance rejection control method for a class of uncertain systems with multiple disturbances

SummaryThe existing active disturbance rejection control (ADRC) method may not provide sufficient disturbance rejection to multiple mismatched disturbances for the fractional order systems. In this paper, a composite disturbance rejection approach is developed for a class of fractional order uncertain systems, by synthesizing the fractional order ADRC (FOADRC) approach and a disturbance observer (DO)‐based compensation scheme. Taking advantage of more disturbance information and a filter structure, an improved DO is developed to achieve precise estimation of disturbances in the presence of sensor noises. In addition, a state transformation is developed to convert the system into a simple integral chain model with only matched disturbances. Then a composite control law is designed to compensate the disturbances and provide satisfying dynamic performance. The efficiency of the proposed method is demonstrated by a numerical simulation and an actual servo control simulation, as well as the comparison with two kinds of the existing ADRC methods and the commonly used integral sliding mode control (I‐SMC) method.

Active disturbance rejection control for unmanned tracked vehicles in leader–follower scenarios: Discrete-time implementation and field test validation

This paper presents a systematic design of an active disturbance rejection control (ADRC) system for unmanned tracked vehicles (UTVs) in leader-follow formation. Two ADRC controllers are designed for the lateral and the longitudinal channels of the UTV based on control errors in the cross-track and the along-track directions. Through simulations, the proposed ADRC approach is first shown to outperform the conventional PI/PID controllers in scenarios involving sudden changes in the leader motion dynamics, slippage disturbances, and measurement noise. Then, a comprehensive experimental validation of the proposed leader–follower control is performed using a laboratory UTV equipped with a camera and laser sensors (to enable the calculation of error signals). In order to provide more effective interaction between the human (leader) and the UTV (follower) during the leader–follower task, a camera-based subsystem for human pose recognition is developed and deployed. Finally, the experimental results obtained outdoors demonstrate that the proposed ADRC-based leader–follower UTV control system achieves high tracking capabilities, robustness against slippage disturbances, and adaptability to changing environmental conditions.

Output tracking for nonlinear stochastic systems driven by bounded and colored noises

In this paper, we consider practical tracking problem for a class of nonlinear stochastic systems driven by bounded and colored noises by means of active disturbance rejection control approach. The nonlinear extended state observer with homogeneous weighted functions is constructed to estimate in real time the unmeasurable state and the total stochastic disturbance that affects system performance. An observer-based output feedback is designed to guarantee the almost surely practical convergence of the tracking errors. The existence of the global weak solution of the closed-loop system is proved and the tracking convergence accuracy is shown to be higher than that of linear one under the same tuning parameters. Some numerical simulations are carried out to validate the effectiveness of the proposed controller.

Trajectory Tracking Control of Pneumatic Servo System: A Variable Gain ADRC Approach.

In this article, a novel error-driven variable gain active disturbance rejection control (ADRC) approach is developed for pneumatic servo system, and the desired performance of trajectory tracking and the disturbance rejection can be guaranteed. The proposed variable gain ADRC includes three parts: 1) variable gain tracking differentiator (TD); 2) variable gain extended state observer (ESO); and 3) variable gain error feedback controller (EFC). The proposed variable gain TD is noise tolerant and possesses a variable gain, which can be dynamically adjusted according to the tracking error, and the performance for tracking the reference signal and extracting its derivative is improved. The variable gain ESO is also equipped with a variable gain driven by estimation errors to improve the estimation performance. Then, the variable gain EFC is further designed to improve control accuracy. Finally, simulations and experimental results are presented to verify the efficiency of the proposed methods.

Output feedback stabilization for a wave–ODE cascaded system subject to uncertain disturbance

AbstractIn this paper, we consider output feedback stabilization for a wave–ODE cascaded system with uncertain disturbance flowing the control end. Firstly, a disturbance estimator is designed by the new active disturbance rejection control (ADRC) approach that we propose two auxiliary systems. Then, we design an observer for the coupled system based on the idea that copy of the original system plus injection of the output estimation error. Finally, by the backstepping method, we design an output feedback control and obtain the exponential stabilization of the closed‐loop system, which consists of the original coupled system, the observer, two new auxiliary systems, and the control. Due to the existence of the in‐domain anti‐damping in wave equation, the proposed two auxiliary systems are different from those in the previous literature. And their designs are inspired by the design idea of the observer. Some numerical simulations are given to illustrate the effectiveness of the control.

Variable structure control based active disturbance rejection control of unstable non-minimum phase delayed processes

The standard active disturbance rejection control (ADRC) method does not work for controlling unstable, non-minimum phase delayed systems. To solve this issue, a variable structure control (VSC) based ADRC approach is proposed for controlling unstable non-minimum phase industrial processes in this work. Tuning of control parameters for optimal control performances is accomplished with the particle swarm optimization (PSO) based approach. The performance of the proposed VSC-based ADRC approach is numerically studied on an unstable non-minimum phase (UNMP) process with delay and a u-tube steam generator (UTSG) level control system. It is found that the proposed control method is able to provide a fast response, zero steady-state error, and robustness against process uncertainties and load disturbances.

The Design of a Reaction Flywheel Speed Control System Based on ADRC

The reaction flywheel is a crucial operational component within a satellite’s attitude control system. Enhancing the performance of the reaction flywheel speed control system holds significant importance for satellite attitude control. In this paper, an active disturbance rejection control (ADRC) approach is introduced to mitigate the impact of uncertain disturbances on reaction flywheel speed control precision. The reaction flywheel speed control system is designed as an ADRC controller due to the current challenge of measuring unknown disturbances accurately in the reaction flywheel system. To derive the rotor’s speed observation value and the estimated total disturbances value, the sampled data of the reaction flywheel rotor position and torque control signal are fed into the extended state observer. The estimated total disturbances value is compensated on feedforward control, which could mitigate significantly the effects of various nonlinear disturbances. The paper initially establishes the rationale behind the reaction flywheel ADRC controller through theoretical analysis, followed by analysis of the differences of performance of reaction flywheel control by the ADRC controller and the PID controller in MATLAB/SIMULINK. Simulation results demonstrate the evident advantages of the ADRC controller over the PID controller in terms of speed command tracking capability and disturbances suppression ability. Subsequently, the ADRC controller program and the PID controller program are implemented on the reaction flywheel control circuit, and experiments are conducted to contrast speed command tracking and disturbance suppression. Importantly, the experimental outcomes align with the simulation results.

Active disturbance rejection control with fractional-order model-aided extended state observer

Increasing the observer bandwidth of the extended state observer (ESO) can significantly enhance the disturbance rejection performance of the active disturbance rejection control (ADRC). However, a large observer bandwidth can also amplify the noise and degrade the control quality. This study proposes a novel fractional-order ADRC (FOADRC) approach. A fractional-order model-aided extended state observer (FOMESO) is designed by leveraging available plant information. Under a given observer bandwidth, the disturbance estimation performance of FOMESO is improved, while noise sensitivity is not aggravated. Additionally, FOMESO transforms a typical second-order plant into a fractional-order double-integrator model, reducing the phase lag to below 180∘. Consequently, the derivative component, which is sensitive to noise, is unnecessary in the feedback controller. Simulation and comprehensive comparisons demonstrate that the proposed FOADRC scheme outperforms the traditional ADRC in tracking, noise sensitivity, disturbance rejection, and stability. Furthermore, the proposed FOADRC approach is robust to plant parameter variations. The proposed method is validated through experiments on a permanent magnet synchronous motor speed servo system, confirming its superiority and effectiveness.

Robust Model Predictive Control Based on Active Disturbance Rejection Control for a Robotic Autonomous Underwater Vehicle

This work aims to develop a robust model predictive control (MPC) based on the active disturbance rejection control (ADRC) approach by using a discrete extended disturbance observer (ESO). The proposed technique uses the ADRC approach to lump disturbances and uncertainties into a total disturbance, which is estimated with a discrete ESO and rejected through feedback control. Thus, the effects of the disturbances are attenuated, and a model predictive control is designed based on a canonical model free of uncertainties and disturbances. The proposed control technique is tested through simulation into a robotic autonomous underwater vehicle (AUV). The AUV’s dynamic model is used to compare the performance of a classical MPC and the combined MPC-ADRC. The evaluation results show evidence of the superiority of the MPC-ADRC over the classical MPC under tests of reference tracking, external disturbances rejection, and model uncertainties attenuation.

Anti-disturbance control for a nonlinear flexible beam with velocity disturbance at the boundary

This paper deals with the output feedback stabilization for a nonlinear flexible beam system with a general disturbance at the boundary. An extended state observer is designed to reject the uncertain disturbance estimated by a relatively independent estimator in the feedback loop via the active disturbance rejection control approach. The existence and uniqueness of the solution to the closed-loop beam system are investigated by means of the Galerkin approximation. The asymptotic stability of the closed-loop beam system is shown by utilizing the energy perturbation method. To demonstrate the control performance, numerical simulations are provided by the finite element method.

High-Performance Attitude Control Design of Supersonic Tailless Aircraft: A Cascaded Disturbance Rejection Approach

This paper focuses on the triaxial augmentation ability of the active disturbance rejection control (ADRC) technique on the tailless layout with a fully moving wing tip to achieve high control performance for the supersonic tailless aircraft. Firstly, the stability characteristics and controllability of the flying wing layout are analyzed to determine the coupling characteristics of this kind of aircraft. Secondly, an attitude controller is designed based on ADRC theory, and the linear ADRC frequency domain analysis method is introduced to analyze the influence of the bandwidth of linear extended stator on the control system. In addition, the tuning process of the attitude control law is given. Carrier dropping simulations of flight missions under nominal condition, model parameter perturbation, and wind disturbance are conducted. The results show that the designed controller can achieve full-speed domain triaxial augmentation of supersonic flying wing. This work has the potential to significantly boost the engineering acceptability and robustness of supersonic aircraft control design in real-world scenarios. The presented cascaded ADRC approach can significantly improve the performance and robustness of supersonic vehicles.

Active Vibration Control of a Rotating Mechanical System with a Rigid Coupling using Active Disturbance Rejection Control

The work aims to develop an active control method for mitigating torsional vibration of a rotating mechanical system with a rigid coupling, driven by an electric motor, particularly for suppressing vibration associated with its mechanical resonances. It is commonly known that torsional oscillations in a rotating system, which is normally used for various power transmission systems, can generate significant levels of vibration and noise. In this work, therefore, an active control system that was based on the Active Disturbance Rejection Control approach was utilized to develop an active control system that was robust against uncertainties associated with the internal dynamics and external disturbances affecting the system. The dynamic interactions between the inertias of the electric motor and the load, which were connected through elastic shafts and a rigid coupling, were investigated. The Extended State Observer was used to estimate the generalized disturbance consisting of not only the external disturbances but also the disturbances associated with internal dynamics of the rotating system. The effectiveness of the developed controller was demonstrated, which showed that in the case of the varying load inertia, the control system could still perform well in mitigating the torsional vibration.

Design of an Improved Active Disturbance Rejection Control Method for a Direct-Drive Gearshift System Equipped with Electromagnetic Linear Actuators in a Motor-Transmission Coupled Drive System

In this study, a type of direct-drive gearshift system integrated into a motor-transmission coupled drive system is introduced. It used two electromagnetic linear actuators (ELAs) to perform gearshift events. The adoption of ELAs simplifies the architecture of the gearshift system and has the potential to further optimize gearshift performance. However, a number of nonlinearities in the gearshift system should be investigated in order to enhance the performance of the direct-drive gearshift system. An active disturbance rejection control (ADRC) method was selected as the principal shifting control method due to the simple methodology and strong reliability. The nonlinear characteristics of the electromagnetic force produced by the ELA were subsequently reduced using the inverse system method (ISM) technique. The ADRC approach also incorporated an acceleration feedforward module to enhance the precision of displacement control. The extended state observer (ESO) module used a nonlinear function in place of the original function to improve the ability to reject disturbances. Comparative simulations and experiments were carried out between the ADRC method and improved ADRC (IADRC) method. The outcomes demonstrate the effectiveness of the designed control method. The shift force fluctuates less, and the shift jerk decreases noticeably during the synchronization procedure. In conclusion, combined with the optimized IADRC method, the direct-drive gearshift system equipped with ELAs shows remarkable gearshift performance, and it has the potential to be widely used in motor−transmission coupled drive systems for EVs.

Robust control strategy for generalized N-trailer vehicles based on a dual-stage disturbance observer

Articulated vehicles with multiple trailers also called N-Trailers have been widely used for transportation tasks in industrial applications. Solutions for the control problem of N-Trailers have been formulated mostly for vehicles with solely on-axle hitching or off-axle hitching but in field applications such as agriculture, most of the structures used are Generalized N-Trailers (GNT) which have a combination of on- and off-axle hitching. Moreover, most of the solutions in literature were developed and tested for laboratory-scale platforms under ideal indoor conditions. However, in outdoors conditions, the motion performance is commonly degraded by model uncertainties, slipping of wheels, and trailers localization loss product of noisy or inaccurate sensor data. In this context, this paper reports the use of Active Disturbance Rejection Control (ADRC) with a Dual-Stage Disturbance Observer (DS-DO) to improve the backward trajectory-tracking performance of GNT in no ideal conditions, where the DS-DO aims to attenuate the effects of error propagation on the ADRC compensation loop and improve the overall closed-loop performance. The proposed ADRC+DS-DO has been validated in simulation and real experiments showing overall improvements on the controller effort reduction and reduction of up to 57% on the tracking error against a traditional ADRC approach already existent in the literature.

Clinical Trajectory control for lower Knee rehabilitation using ADRC method

The design and study of the Active Disturbance Rejection Control (ADRC) approach for control and disturbance rejection for lower knee rehabilitation utilizing a residential exoskeleton system are provided in this paper. Linear ADRC (LADRC) and Nonlinear ADRC (NADRC) are two controllers that are considered for control purposes based on the structure of ADRC. The contrasts between them are thoroughly discussed in this work. The LADRC is made up of a tracking differential (TD), a linear proportional derivative (LPD) controller, and a linear extended state observer (LESO), whereas the NADRC is made up of the same LESO but with a nonlinear PD (NPD) and a modified optimized TD (MTD). In terms of robustness against the ability to reject applied disturbances, a comparison of LADRC and NADRC has been done. The fundamental challenge with ADRC is that its constituent parameters must be fine-tuned. Grey Wolf Optimizer (GWO) has been proposed for tuning the parameters of ADRC to have the least amount of error variation in order to improve the controlled system's dynamic performance. When a prescribed disturbing torque is applied, the results of a MATLAB simulation show that the LADRC has greater disturbance rejection capabilities than the NADRC.

Active Disturbance Rejection Control Approach for Double Pendulum Cranes with Variable Rope Lengths

The overhead crane is a typical underactuated system with complicated dynamics and strong couplings. It is widely employed to transport heavy cargoes in many industrial fields. Due to the complexity of working environments, however, cranes often encounter various unfavorable factors, which may degrade the transportation efficiency. To enhance control performance and anti-disturbance ability, this paper proposes an active disturbance rejection control approach based on differential flatness for double pendulum cranes with variable rope lengths. The proposed approach can position the trolley accurately, regulate rope length, and suppress the swing angles of the payload and the hook simultaneously. During the controller design, flat outputs were constructed based on differential flatness technique to deal with system couplings, and the results prove that double pendulum crane system is differentially flat. After that, model uncertainties and external disturbances were estimated by the designed extended state observer. On this basis, a controller was developed based on the feedback control technique. Finally, a series of simulations were carried out to show that the control scheme is effective and robust.