Active disturbance rejection control based on internal model control for a class of processes with large time constant and time delay

A new robust decentralized controller based on a modified linear active disturbance rejection control structure is proposed in this article. In this work, the proposed controller is designed in a two-degree-of-freedom internal model control framework, to overcome the limitations of extended state observer in active disturbance rejection control. In the proposed controller, tuning parameters, that is, observer bandwidth and controller bandwidth are the inverse of the two-time constants, that is, set-point filter and disturbance rejection filter of internal model control (IMC). Moreover, to show the efficacy of the proposed controller, it has been compared with the linear active disturbance rejection controller (ADRC). Furthermore, to exhibit the superiority, an experimentation is conducted on a coupled tank liquid-level multivariable system. From the obtained simulation and experimental results, it is envisaged that the proposed modified linear active decentralized disturbance rejection controller exhibits superior control performance to maintain a precise desired liquid level as compared to the linear ADRC.

This paper investigates linear active disturbance rejection control (ADRC) for processes with time delay. In the past years several modified active disturbance rejection control methods, including Smith predictor based ADRC (SP-ADRC), predictor observer based ADRC (PO-ADRC) and delayed designed ADRC (DD-ADRC) have been proposed to tackle systems with time delay. In this paper it is shown that these modified ADRCs can be interpreted in the framework of a two-degree-of-freedom (TDOF) internal model control (IMC), so the analysis and design can all be done via the well-known IMC framework. With the aid of the TDOF-IMC framework, the three modified ADRCs are compared and some interesting conclusions are drawn. Analysis and simulation results show that PO-ADRC structure is the best delay compensation structure among the three methods. However, the overall performance of the three methods will also depend on the tuned parameters, and the robustness measure is helpful in tuning the parameters to achieve compromise in performance.

Linear active disturbance rejection control for oscillatory systems with large time-delays

Linear motors are widely used in semiconductor packaging equipment to achieve high-speed and high-acceleration linear motion as well as high positioning accuracy. The linear motor XY motion platform is an essential component of semiconductor packaging equipment and consequently, the improvement of its motion performance is of great significance to the packaging industry. The active disturbance rejection controller (ADRC) is the controller which not only inherits the advantages of traditional PID controller which decreases tracking errors based on tracking errors, but also can make system realize high response speed and small overshoot at the same time. The linear active disturbance rejection controller (LADRC) is a linear simplified ADRC with the characteristics of easier parameter tunning. In this paper, LADRC is proposed to be used in the linear motor XY motion platform servo system. System dynamics and disturbances are observed by the linear extended state observer (LESO) and compensated to improve interference rejection capability and stability of the servo system. Besides, the feedforward controller (FFC) is adopted to improve the response speed of the XY platform. A simulation model of the linear motor XY motion platform control system is established to verify the validity of LADRC. Disturbances are applied to the PID, LADRC and LADRC with FFC models respectively. Motion performances under these three situations are compared. The results show that compared with the PID control, linear active disturbance rejection control combined with feedforward compensation can improve the tracking performance and anti-interference ability of the system.

This study proposes a systematic approach for implementing discrete-time Linear Active Disturbance Rejection Control in the closed-loop regulation of power converters. The continuous-time Linear Extended State Observer was discretized using the zero-order hold method to obtain a current estimator-based Linear Extended State Observer that is suitable for real-time implementation. The design considerations for discrete-time Linear Active Disturbance Rejection Control, including the selection of observer and controller parameters and the sampling period, are addressed. For performance comparison, a PI controller was designed and implemented in discrete time. The control schemes were evaluated via MATLAB/Simulink (2025b) simulations and real-time closed-loop experiments on a microcontroller to assess the transient response, disturbance rejection capability, and steady-state accuracy of the buck converter. The simulation and experimental results demonstrate that the discrete-time Linear Active Disturbance Rejection Control incorporating a current-estimator-based Linear Extended State Observer significantly outperforms the PI controller in terms of transient response and disturbance rejection capability. From this perspective, this study provides a meaningful contribution to the limited literature on linear extended state observer-based discrete-time Active Disturbance Rejection Control methods.

Drum water level systems show strong disturbance, big inertia, large time delay, and non-linearity characteristics. In order to improve the antidisturbance performance and robustness of the traditional active disturbance rejection controller (ADRC), an improved linear active disturbance rejection controller (ILADRC) for drum water level is designed. On the basis of the linear active disturbance rejection controller (LADRC) structure, an identical linear extended state observer (ESO) is added with the same parameters as that of the original one. The estimation error value of the total disturbance is introduced, and the estimation error of the total disturbance is compensated, which can improve the control system’s ability to suppress unknown disturbances, so as to improve the antidisturbance performance and robustness. The antijamming performance and robustness of LADRC and ILADRC for drum water level are simulated and analyzed under the influence of external disturbance and model parameter variation. Results show that the proposed control system ILADRC has shorter settling time, smaller overshot, and strong anti-interference ability and robustness. It has better performance than the LADRC and has certain application value in engineering.

A robust cascade control system based on active disturbance rejection controller (ADRC) is originally developed for accurate position control of a pneumatic servo system, which is usually characterized by nonlinearity, uncertainty, and disturbance. The proposed control system consists of inner and outer control loops. Particularly, a linear ADRC (LADRC) is utilized to adjust valve position for a linear spool valve dynamics in the inner loop. A nonlinear ADRC (NADRC) is designed to control the position of a nonlinear pneumatic actuator subsystem in the outer loop. LADRC and NADRC contain linear and nonlinear extended state observers (ESOs), respectively. The ESO can estimate both unknown nonlinear dynamics and external disturbances and thus make the ADRC robust against system uncertainties and disturbances. Simulation results successfully demonstrate the effectiveness and robustness of the proposed cascade control system. The stabilities of the inner and outer control loops were proved separately using a Lyapunov approach.

Tuning of linear active disturbance rejection controllers for second-order underdamped systems with time delay

Aiming at the problem of anti-swing and positioning of underactuated crane, this paper proposes a control strategy of underactuated bridge crane based on Linear Active Disturbance Rejection Control and controller parameter optimization method. Distinguished from other conventional control strategies of bridge crane, this method does not require any approximate decoupling or linearization of the crane model and allows the model to have some certain uncertainty, friction and air resistance of the system are also considered. At the same time, for the parameter tuning problem of the sensors, the bird swarm optimization algorithm is applied to optimize the parameters. And the excellent control performance of this method has been proved by simulation.

This paper proposes the analysis and design of the linear active disturbance rejection controller (LADRC) for the pitch angle model of a large wind turbine generator (WTG). Since the transfer function of the pitch control system exhibits nonminimum-phase characteristics, the parameters of LADRC are difficult to tune using the conventional bandwidth method. On the basis of PI controller parameters to first-order LADRC parameters, an optimization problem is proposed in this paper to find the parameters of an LADRC for the pitch control system under the constraint of robustness measure, and the extremum-seeking (ES) algorithm is used to solve the problem. Simulation results show that LADRC can achieve better tracking and disturbance rejection performance than traditional PI control without loss of robustness against time delay.

Linear active disturbance rejection control (ADRC) is known for its simplicity and its performance in disturbance attenuation. Currently, tuning of linear ADRC is via the bandwidth idea proposed in [1]. It is first shown that there are some limitations using only two bandwidths to tune the linear ADRC controllers. In this paper, tuning of linear ADRC with extra model dynamic information is investigated. It is shown that the available model dynamic information used in generalized ADRC (GADRC) can be realized by the observer gain and the controller gain of the conventional linear ADRC, thus extends the applicability of conventional linear ADRC. Simulation results show that with extra model dynamic information incorporated, by tuning the observer gain and controller gain, the performance of a conventional linear ADRC can indeed be improved, especially for non-minimum phase and time-delayed processes.

In this paper, a Linear Active Disturbance Rejection Control (LADRC) scheme is presented for the uncertain first order delay time plant. The stable boundary is obtained, which make the tuning process very easy. The controller can be applied to a plant with large time delay. The uncertainty of the system is characterised by the Kharitonov theorem and the gain–phase margin tester approach, combined with the D–partition method, is utilised to determine specific performance boundaries. The analysis is conducted graphically and the feasible regions are explicitly shown in the parameter plane. Numerical simulation is provided to demonstrate the effectiveness of the proposed controller.

In the framework of the traditional active disturbance rejection controller (ADRC), the state error feedback utilizes estimated values from the extended state observer, which may introduce phase lag. Therefore, academic researchers have proposed a modified version called the improved linear ADRC that employs output values from the plant for state error feedback except the output value from the extended state observer. However, there is limited literature exploring the relationship between traditional linear ADRC and improved linear ADRC. To address this gap, this article establishes mathmatical relationship between traditional linear ADRC and improved linear ADRC from the generalized PID control perspective, highlighting their distinctions in the frequency domain. Compared to the traditional ADRC, the improved ADRC incorporates differential terms and offers a novel approach to realize the generalized PID control via generalized PID interpretation. And to be more specific, the improved ADRC is a new way to realize the generalized PID control by three tuned parameters, and the number of parameters of the improved ADRC is fewer than that of the generalized PID control. From the time domain, numerical simulation results demonstrate that improved ADRC exhibits superior control performance by eliminating overshoot during set value tracking processes compared to the traditional ADRC. From the disturbance rejection simulations in direct current to direct current converter (DCDC), the improved ADRC can achieve better disturbance rejection performance than the traditional ADRC. The DC bus voltage drop values of the traditional ADRC are 55.8 V and 32 V; thus, the biggest voltage drop is 55.8 V, which is 7.44 times the the improved ADRC. The voltage rise of improved ADRC can be neglected compared to the voltage rise of the traditional ADRC. From the tracking performance perspective, the time to fully reach the reference value of the traditional ADRC is about 0.3 s, and the time to fully reach the reference value of the improved ADRC is about 0.15 s.

In the present work, design and analysis of Active Disturbance Rejection Control (ADRC) method has been presented for control and disturbance rejection of magnetic levitation (Maglev) system. Based on the structure of ADRC, two controllers are considered for the control purpose suggested system: Linear ADRC (LADRC) and Nonlinear ADRC (NADRC). A performance comparison has been made between LADRC and NADRC in terms of robustness against variation of parameters and the capability to reject applied disturbance. The main difficulty with ADRC is the necessity to tune its constituent parameters. Particle Swarm Optimization Method (PSO) has been suggested to tune the parameters of ADRC to have minimum error variance such to enhance the dynamic performance of the controlled system. The results based on MATLAB simulation indicated that LADRC gives better robustness characteristics than NADRC. Also, it has been reported that the LADRC has better disturbance rejection capabilities than NADRC when prescribed disturbing force is applied on the ball mass.

Active disturbance rejection control (ADRC) was originally given in a nonlinear gain structure to better accommodate the dynamic uncertainties and disturbances. However, the resulting complexity in a theoretical analysis and in the parameter tuning inhibits the applications of an ADRC. ADRC was linearized and parameterized for a practical convenience. Since linear ADRC (LADRC) and nonlinear ADRC (NLADRC) each has its own advantages and disadvantages, choosing between LADRC and NLADRC is rather difficult. As a matter of fact, there is a lack of quantitative analysis and comparison between LADRC and NLADRC. This paper first gives an easy solution in the parameter tuning of the nonlinear extended state observer, followed by a quantitative analysis and comparison study on LADRC and NLADRC; then, an LADRC/NLADRC switching control (SADRC) scheme is proposed and its stability is analyzed; finally, the SADRC scheme is verified by experiment using the ball–beam platform. The proposed SADRC takes the advantage of the additional performance improvement associated with the NLADRC, but make it easier to use.