Traditional Active Disturbance Rejection Control Research Articles

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.

Current Control Method of Vehicle Permanent Magnet Synchronous Motor Based on Active Disturbance Rejection Control

Due to the frequently changing working conditions and complex operating environment of electric vehicle permanent magnet synchronous motor(PMSM), the motor parameters change dramatically. However, the performance of the PI current regulator, which is the most widely used, is sensitive to motor parameters and has weak robustness, which will lead to the deterioration of motor control system performance. To address this problem, active disturbance rejection control (ADRC) technology is applied to the PMSM current loop control. Firstly, the traditional ADRC current regulator is designed, and the performance and parameter tuning laws of the extended state observer are analyzed by the method of frequency domain analysis. Then, the traditional ADRC algorithm is improved in three aspects: observation error compensation, utilization of model information and anti-windup. After that, simulations and bench test validation are performed. The simulation results show that the improved ADRC current regulator is more robust in the face of parameter changes. The torque step test results show that the improved ADRC current regulator has fast dynamic response without overshoot and has high robustness when the motor parameters change. The dynamic test results show that the improved ADRC current regulator has high robustness when the load, speed and motor parameters change, and the anti-windup measures designed can effectively overcome the integral saturation phenomenon.

Q-learning–based practical disturbance compensation control for hypersonic flight vehicle

Aiming at the attitude control problem of hypersonic flight vehicle, a compound control strategy based on the disturbance compensation technique and Q-learning optimization is proposed. Firstly, a three-channel independent control scheme based on the super-twisting extended state observer (STESO) is proposed such that coupling among channels, uncertainties, and external disturbances can be estimated and compensated in real time. Secondly, the Q-learning mechanism is introduced to optimize the control parameters while keeping the control structure unchanged. Lastly, the convergence of the STESO is analyzed by the Lyapunov theory, and some numerical simulation results are carried out to verify the effectiveness of the proposed strategy. Compared with the traditional linear active disturbance rejection control, the proposed method can avoid a lot of manual parameter tuning process and also has better performance.

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.

Secure Control of Networked Inverted Pendulum Visual Servo Systems Based on Active Disturbance Rejection Control

This paper investigates secure control of Networked Inverted Pendulum Visual Servo Systems (NIPVSSs) based on Active Disturbance Rejection Control (ADRC). Firstly, considering the network- and image-induced delays in conjuction with computational errors caused by image processing and image attacks, the model of NIPVSSs is established. Secondly, the limitations of the traditional Single-Input-Single-Output (SISO) ADRC used in NIPVSSs with disturbance are revealed. The limitations are that the ESO used in the traditional SISO ADRC brings large steady-state error, and the NLSEF used in the traditional SISO ADRC can achieve stable control of pendulum angle, but cannot achieve stable control of cart position. Thirdly, a new Single-Input-Multi-Output (SIMO) ADRC method is proposed for NIPVSSs with disturbance. In the new SIMO ADRC method, the new ESO is designed by introducing additional first and second derivatives of error to reduce the steady-state error. In addition, the new NLSEF is developed by taking both the calculated cart position and pendulum angle as inputs to achieve dual stable control of pendulum angle and cart position. Finally, combined with the designed ADRC parameter-tuning strategy, the results from simulation and real-world experiments confirm the effectiveness and feasibility of the proposed method.

Model predictive and compensated ADRC for permanent magnet synchronous linear motors

Traditional linear active disturbance rejection control (LADRC) may have difficulty to achieve a rapid precise disturbance rejection for a permanent magnet synchronous linear motor (PMSLM). By making use of model information, a model predictive and compensated LADRC (MPLADRC) method is proposed in this paper. In this method, a model compensated extended state observer (MESO) is designed to transform the controlled object into an established mathematical model through total disturbance compensation. Meanwhile, considering the delay problem of MESO, a phase advance module is designed to improve the estimation speed of MESO for system disturbance and state, thus the MESO can rapidly compensate various uncertainty disturbances to the controlled object in real time. The model predictive controller (MPC) is then designed based on the mathematical model, and its optimal control law is then obtained through a quadratic objective function to further suppress the disturbance unobserved by the designed MESO. The proposed method can thus realize a dual-degree-of-freedom disturbance rejection through the MESO and MPC. The simulation and experimental results validate the effectiveness of the proposed MPLADRC in rapid anti-disturbance and fast positioning for the motion control of the PMSLM.

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.

A Fuzzy Backstepping Attitude Control Based on an Extended State Observer for a Tilt-Rotor UAV

In order to overcome the influence of internal and external disturbances caused by rotor tilt motion and gust disturbance on the full flight mode control of a tilt-rotor unmanned aerial vehicle (UAV), a design method using fuzzy backstepping control based on an extended-state observer (FBS-ESO) is proposed. In this paper, fuzzy control is used to tune the parameters of the backstepping control law online, and the extended-state observer estimates the total disturbance of the controlled system to improve the controller’s robustness and anti-disturbance capability. This paper designs the attitude control system of a tilt-rotor UAV based on an FBS-ESO controller. The control performance of the FBS-ESO controller is tested in a hardware-in-loop simulation of the attitude control system. The simulation results show that changing the rotor tilt angle will destroy the stability of the traditional backstepping controller and active disturbance rejection controller (ADRC). In contrast, the FBS-ESO controller maintains good control performance. In addition, the performance of the FBS-ESO controller is not be significantly affected by adding external gust disturbance or changing the UAV parameters in the simulation. These disturbances significantly impact the traditional backstepping controller and ADRC. Therefore, the FBS-ESO controller has better anti-disturbance capabilities and robustness, as well as higher attitude control accuracy.

Accurate Modeling and Homing Control for Parafoil Delivery System Based on Wind Disturbance Rejection

Parafoil delivery systems play an irreplaceable role in the area of the airdrop supply and aircraft recovery. Their main function is to transport the payload to the target position. The system applies a large flexible parafoil to provide the lift force and control the flight direction. The parafoil is strongly nonlinear and vulnerable to the wind disturbance. To solve this problem, in this study, we explore a novel flexible modeling method and a homing control methodology for the parafoil. First, an 8-degree-of-freedom dynamic model is built. By clarifying the functions of the different aerodynamic coefficients, the model can maximally simulate the flight states of the system. Then, a trajectory planning method based on a Gaussian pseudospectral method is presented to calculate the optimal reference trajectory by considering the influence of the constant wind. Next, the wind disturbance, such as constant wind and gusts, is compensated by an improved active disturbance rejection controller (ADRC) in the trajectory tracking. Finally, compared with the traditional PID and ADRC, the results of the flight experiment illustrate the correctness and feasibility of the proposed modeling and homing control methodology.

Bus Voltage Control of Photovoltaic Grid Connected Inverter Based on Adaptive Linear Active Disturbance Rejection

According to the traditional voltage and current double closed-loop control mode, the inverter management strategy for photovoltaic grid connection has insufficient anti-interference ability and slow response. This paper proposes a control strategy that applies adaptive-linear active disturbance rejection control (A–LADRC) to the outer loop control to achieve the purpose of anti-interference. The control strategy uses the linear extended state observer (LESO) to evaluate external interference caused by the change of external conditions and the internal disturbance caused by parameter uncertainty. PD controller compensates the disturbances and adds adaptive control to simplify parameter adjustment. Finally, this paper takes advantage of Lyapunov theory to conduct stability analysis. Compared with the traditional linear active disturbance rejection control (LADRC), the superiority of this control strategy is verified. The experimental results show that the system has better control performance and anti-interference ability in the face of various disturbances.

Ship Dynamic Positioning Control Based on Active Disturbance Rejection Control

Nowadays, Dynamic Positioning (DP) is applied to various tasks such as subsea pipeline laying and the requirements for the positioning performance in marine operations are higher and higher. The main objective of this paper is to design a DP controller based on the Active Disturbance Rejection Control (ADRC) to solve the problems of long response time, large overshoot and low positioning accuracy in ship positioning. Firstly, the mathematical models of the ship and environmental disturbances are established. Secondly, the basic principle of ADRC is described. Meanwhile, stability analysis of the control system is introduced. Thirdly, ADRC is improved by the fal function filter and phase prediction method which solve the problem of dither and phase delay in tracking differentiators. Finally, simulations are carried out to verify the performance of the designed ADRC and the improved ADRC. Several simulation results show that the designed ADRC can realize the fixed-point control of the ship, which effectively solves the problems of long response time, overshoot and positioning accuracy, and compared with the traditional ADRC, the improved ADRC can reduce the error of straight track control, which indicates that ADRC can meet the requirements for the positioning performance and has a strong application value.

ADRC Control System of PMLSM Based on Novel Non-Singular Terminal Sliding Mode Observer

In an attempt to solve the problem of the many parameters of the traditional active disturbance rejection controller (ADRC) and to accurately estimate the mover position and speed required by a permanent magnet synchronous linear motor (PMLSM) system, an improved ADRC and a novel nonsingular fast terminal sliding mode observer (NFTSMO) are proposed. Firstly, the traditional first-order ADRC is simplified, the tracking differentiator (TD) module is removed, and the direct error is used to replace the nonlinear function in the extended state observer (ESO) and nonlinear state error feedback (NLSEF) module. Based on the traditional NFTSMO, the smooth back electromotive force (EMF) is obtained by adding the TD to reduce the phase delay caused by the low-pass filter in the traditional sliding mode observer (SMO), and the actuator position and speed information are modulated from the observed back EMF based on the principle of a phase-locked loop (PLL). Simulation and experiments show that this method not only simplifies the system structure of PMLSM but also optimizes many parameters in ADRC while retaining the original excellent performance. Compared with the traditional NFTSMO, the improved NFTSMO enhances the observation accuracy, reduces the chattering phenomenon of the system, and improves the robustness of the system.

A Model-Based Unmatched Disturbance Rejection Control Approach for Speed Regulation of a Converter-Driven DC Motor Using Output-Feedback

The speed regulation problem with only speed measurement is investigated in this paper for a permanent magnet direct current (DC) motor driven by a buck converter. By lumping all unknown matched/unmatched disturbances and uncertainties together, the traditional active disturbance rejection control (ADRC) approach provides an intuitive solution for the problem under consideration. However, for such a higher-order disturbed system, the increase of poles for the extended state observer (ESO) therein will lead to drastically growth of observer gains, which causes severe noise amplification. This paper aims to propose a new model-based disturbance rejection controller for the converter-driven DC motor system using output-feedback. Instead of estimating lumped disturbances directly, a new observer is constructed to estimate the desired steady state of control signal as well as errors between the real states and their desired steady-state responses. Thereafter, a controller with only speed measurement is proposed by utilizing the estimates. The performance of the proposed method is tested through experiments on dSPACE. It is further shown via numerical calculations and experimental results that the poles of the observer within the proposed control approach can be largely increased without significantly increasing magnitude of the observer gains.

Super-Twisting Hybrid Control for Ship-Borne PMSM

In the field of ship-borne PMSM, there exists the sea wave fluctuations, external disturbances thus model uncertainties are always challenging the control design of ship-borne permanent magnet synchronous motors (PMSMs). To deal with this problem, a super-twisting extended state observer (SESO) is used in this paper to observe state variables accurately. Moreover, to solve the phase delay problem in active disturbance rejection control (ADRC), Taylor’s formula-based tracking differentiator (TTD) is applied in the proposed hybrid control strategy. With appropriate compensate of disturbance, denoted as super-twisting hybrid control, the controlled position signal can follow the reference with small tracking errors, also with improved dynamic performance. Simulation results show that the proposed super-twisting hybrid control has the better anti-disturbance and tracking performance compared with the traditional ADRC. Lastly, semi-physical experimental results further validate the effectiveness of the control strategy for ship-borne PMSMs.

Nonlinear Active Disturbance Rejection Control Strategy for Permanent Magnet Synchronous Motor Drives

Active disturbance rejection controller (ADRC) possesses the considerable capability of improving the robustness of the permanent magnet synchronous motor (PMSM) drives. Nevertheless, the traditional linear ADRC (LADRC) and nonlinear ADRC (NLADRC) have their specific characteristic disturbance range of application. To further expand the disturbance range so as to improve the robustness against the disturbances, a novel NLADRC is proposed, which replaces the traditional linear function with a nonlinear function (NLF). And it is applied as the speed regulator for PMSM drives. Considering the accuracy and the dynamic performance of the disturbance estimation at the same time, an NLF is developed, and its describing function is established accordingly. Based on the above analysis, the NLADRC employing a cascaded nonlinear extended state observer is constructed to guarantee the relatively rapid and accurate disturbances estimation and compensation. Then, via the describing function technique, the theoretical frequency-domain analysis for the stability, the disturbance estimation performance, and the stiffness of the proposed NLADRC-based sensorless PMSM drive is given. Finally, the validity of the proposed scheme is verified experimentally on a 2.2-kW PMSM drive platform.

Extended state observer based fractional order controller design for integer high order systems

In this paper, based on the extended state observer (ESO) and on a fractional order controller (FOC), composed of an integer order PID cascaded with a fractional order filter (FOF), a new control scheme for an n th order integer plant is proposed. The ESO is used to estimate and cancel the unknown internal dynamics and the external disturbance. Afterwards, an FOC is designed to resolve the set-point tracking problem. An analytical and systematic method is proposed to design the FOC. This method is based on the Internal Model Control (IMC) and the Bode’s Ideal Transfer Function (BITF). Therefore, the proposed control structure improves the robustness and performance of the traditional linear active disturbance rejection control (LADRC), especially for the open-loop gain variation. In addition, since the system be controlled is an n th order, a general form of the BITF is also proposed. Numerical simulations on a nonlinear model and experimental results on a cart-pendulum system design illustrate the effectiveness of the suggested ESO-PID-FOF scheme for the disturbance rejection, the set-point tracking and robustness. A comparison with the results obtained using the standard LADRC is also presented.

Application of social spider optimization and improved active disturbance rejection controller in hierarchical control of cooperative multi-lift with four unmanned helicopters

To achieve the three-dimensional free movement of the slung load, a load-leading hierarchical control strategy has been adopted recently which divides the cooperative multi-lift system into a load layer, a cable layer, and an aircraft layer. But there exists a non-convex optimization problem in the cable layer when computing the force of each cable, and more control difficulties of the aircraft due to the additional disturbances resulting from the load movement. To solve these problems, an application of the social spider optimization (SSO) algorithm and the improved active disturbance rejection controller (IADRC) in hierarchical control of cooperative multi-lift with four unmanned helicopters is proposed in this study. First, the unmanned helicopters as well as the load are modeled. Then the three layers mentioned above are designed, respectively. Specifically, an optimization method combining SSO with the MATLAB/fmincon function is proposed to solve the non-convex problem in the cable layer. And within the unmanned helicopter layer, the fuzzy theory is introduced into the nonlinear error feedback control strategy of the traditional active disturbance rejection controller (ADRC) to realize the control of the unmanned helicopter. At last, some simulations are carried out, and the results indicate that the system has higher calculation efficiency, smaller steady-state error, and better adaptability to trajectory change or load release with the designed hierarchical control strategy.

Model predictive control of direct-driven surface-mounted permanent magnet synchronous generator based on active disturbance rejection controller

PurposeThis paper aims to mainly discuss how to suppress the disturbances accurately and effectively in the wind energy conversion system (WECS) of the direct drive surface mount permanent magnet synchronous generator (SPMSG).Design/methodology/approachThe disturbances in wind energy conversion system have seriously negative influence on the maximum power tracking performance. Therefore, a model predictive control (MPC) method of model compensation active disturbance rejection control (ADRC) strategy in parallel connection is designed, which optimizes the speed tracking performance compared with the existing control strategy of MPC and ADRC in series connection. Based on the traditional ADRC, a multi parameter model compensation ADRC strategy is added to better estimate the disturbances. At the same time, a torque feedback strategy is added to compensate the disturbances caused by load torque and further optimize the speed loop tracking performance.FindingsThe simulation results show that the designed control method has advantages than the traditional control method in compensating the disturbances and tracking the maximum power more effectively.Originality/valueThe simulation results show that the designed control method is superior to the traditional proportional control method, which can better compensate the internal and external disturbances and track the maximum power more effectively.

Adaptive neural network-based active disturbance rejection flight control of an unmanned helicopter

To enable the unmanned helicopter to fly autonomously in precise paths and reduce the influence of internal and external unknown disturbances of the unmanned helicopter, this paper proposes the adaptive radial basis function (RBF) neural network-based active disturbance rejection controller (ADRC). This controller is abbreviated as RBF-ADRC. Firstly, this paper introduces the flight dynamics model of the unmanned helicopter and the control features of the traditional ADRC. Subsequently, this paper uses modern control theory to establish a state observer and uses adaptive RBF neural network to estimate the unknown total disturbance. Finally, this paper constructs the unmanned helicopter's trajectory tracking control system based on the RBF-ADRC controller. The simulation results of the spiral ascent and the “8”-figure climb maneuver flight prove that the anti-disturbance, robustness and tracking accuracy of the RBF-ADRC are better than the traditional ADRC and proportion-integration-differentiation (PID) control methods.

Electro-hydraulic position servo system based on sliding mode active disturbance rejection compound control

This study proposes a compound control method based on sliding mode and active disturbance rejection control to address the difficulty of controlling the cutting head for boom-type roadheader with parameter changes and uncertain disturbances. The fastest discrete tracking differentiator and extended state observer based on the traditional active disturbance rejection control are designed. Additionally, the controller of the sliding mode and active disturbance rejection control is constructed. Theoretical analysis indicates that the proposed controller ensures asymptotic stability, despite the existing uncertain disturbances. Moreover, a system based on AMESim and MATLAB/Simulink Co-simulation model is developed to further verify the performance of proposed algorithm. Compared with traditional active disturbance rejection control, proportional-integral-derivative(PID) and sliding mode control, co-simulation results demonstrate that the sliding mode active disturbance rejection compound control improves the tracking accuracy and robustness of the position servo system.