A modified active disturbance rejection control strategy based on cascade structure with enhanced robustness

The PID control strategy is usually used to control the motor in the electric servo loading system CESLS), however there are some nonlinear factors such as mechanism clearance and surplus torque in the loading process, the conventional PID control method can't guarantee the control performance and the loading accuracy of the ESLS. A position feed-forward compensation controller is introduced in the ESLS, and an outer loop active disturbance rejection control (ADRC) strategy is designed to eliminate position disturbance and surplus torque disturbance in this paper. The method of “observation + compensation” used in the outer loop ADRC controller is not only to suppress the surplus torque, but also to improve the steady-state performance of the ESLS. The simulation result shows that the electric servo loading system based on ADRC strategy can effectively improve the tracking accuracy of the ESLS and enhance the stability of the ESLS.

In order to overcome the problems of linear control method, which are unfavorable performance and highly depending on the accuracy of vehicle model, active disturbance rejection control(ADRC) strategy is used to complete active front wheel steering(AFS) control in this paper. According to the general principle of ADRC, a second order ADRC strategy is designed. Under the operation conditions of high speed single lane change and braking on µ-split road, the control performance is studied by means of simulation. The results show that the ADRC strategy can realize AFS control effectively and decrease the dependence on the accuracy of vehicle model. At the same time, the performance is better than that of PID control.

Integrated flight-propulsion control (IFPC) in cruise mode is under study for ramjet powered supersonic vehicle. The longitudinal flight control and propulsion control model are built with system disturbance and measurement noise. We propose a decoupling active disturbance rejection control (ADRC) scheme for IFPC design. For velocity control loop, a second-order linear extended state observer (ESO) is used. The altitude control loop includes inner pitch angle control and outer altitude control. Two third-order linear ESOs are applied in the altitude control loop. These ESOs estimate the disturbances on altitude and pitch angle, and their parameters are determined by their bandwidth. Two tracking-differentiators (TD) ensure the transient process of velocity and altitude. The linear combinations of state error feedback are applied. The control design eliminates coupling effects between altitude and velocity and attenuates measurement noise.

Automatic carrier landing system based on active disturbance rejection control with a novel parameters optimizer

Hybrid underwater gliders (HUGs) combine buoyancy-driven gliding with propeller-assisted propulsion, offering extended endurance and enhanced mobility for complex underwater missions. However, precise depth control remains challenging due to system uncertainties, environmental disturbances, and inadequate adaptability of conventional control methods. This study proposes a novel optimized line-of-sight active disturbance rejection control (OLOS-ADRC) strategy for HUG depth tracking in the vertical plane. First, an Optimized Line-of-Sight (OLOS) guidance dynamically adjusts the look-ahead distance based on real-time cross-track error and velocity, mitigating error accumulation during path following. Second, a Tangent Sigmoid-based Tracking Differentiator (TSTD) enhances the disturbance estimation capability of the Extended State Observer (ESO) within the Active Disturbance Rejection Control (ADRC) framework, improving robustness against unmodeled dynamics and ocean currents. As a critical step before costly sea trials, this study establishes a high-fidelity simulation environment to validate the proposed method. The comparative experiments under gliding and hybrid propulsion modes demonstrated that OLOS-ADRC has significant advantages: the root mean square error (RMSE) for depth tracking was reduced by 83% compared to traditional ADRC, the root mean square error for pitch angle was decreased by 32%, and the stabilization time was shortened by 14%. This method effectively handles ocean current interference through real-time disturbance compensation, providing a reliable solution for high-precision HUG motion control. The simulation results provide a convincing foundation for future field validation in oceanic environments. Despite these improvements, the study is limited to vertical plane control and simulations; future work will involve full ocean trials and 3D path tracking.

Active disturbance rejection control for spacecraft relative motion in libration point orbits subject to actuator saturation and time-delays

Single-stage three-phase isolated matrix rectifiers (TIMRs) have high efficiency and compact configurations and are very suitable for electric vehicle (EV) chargers. However, external and internal disturbances challenge the robustness and tracking performance of EV chargers, and conventional proportional integral (PI) controllers cannot solve the unmodeled dynamics and the uncertainty of model parameters in the system, so other feedback controllers, which have disturbance rejection performance, need to be designed. Therefore, this article proposes a dual-loop control strategy based on active disturbance rejection control (ADRC) to guarantee high-speed dynamic response and strong robustness against disturbances. First, the dynamic model of the TIMR is established and divided into two parts to facilitate the controller design. Second, the extended state observer (ESO) is designed to estimate and compensate for the disturbances of the system, and the inner current loop and the outer current loop are designed based on the second-order ADRC. In addition, a simplified parameter-tuning method of the proposed control scheme is presented in detail. Finally, a frequency-domain analysis is given to explain the robust performance of the proposed control scheme. The effectiveness and feasibility of the proposed controller are verified by simulation and experimental results.

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors, such as dynamic uncertainty and parameter perturbation, an improved active disturbance rejection control (ADRC) strategy was proposed. The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor. Then the three parts of ADRC were improved by parameter perturbation and external disturbance; the fast tracking differentiator was introduced into linear and non-linear combinations; the nonlinear state error feedback was proposed using synovial control; the extended state observer was determined by nonlinear compensation. In addition, the grey wolf algorithm was used to set the parameters of the three parts. The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes, which lay foundation for the motor application.

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.

Although the structure of PI controller is simple, there are some flaws. In order to overcome the contradictions between the rapid response and overshoot for speed, the model of active disturbance rejection control (ADRC) was established in the paper. The transition process for a given speed was got by tracking - differentiator (TD). The sum of internal and external disturbance is estimated by the extended state observer (ESO). The capability of resisting disturbance is improved for the disturbance compensated timely. Permanent magnet synchronous motor (PMSM) direct torque control based on ADRC scheme is realized. The simulation results have shown its availability.

Finite-time output consensus control of nonlinear uncertain multi-agent systems via extended state observer

The control stability and accuracy of quad tiltrotor UAVs is improved when encountering external disturbances during automatic flight by an active disturbance rejection control (ADRC) parameter self-tuning control strategy based on a radial basis function (RBF) neural network. Firstly, a nonlinear flight dynamics model of the quad tiltrotor UAV is established based on the approach of component-based mechanistic modeling. Secondly, the effects of internal uncertainties and external disturbances on the model are eliminated, whilst the online adaptive parameter tuning problem for the nonlinear active disturbance rejection controller is addressed. The superior nonlinear function approximation capability of the RBF neural network is then utilized by taking both the control inputs computed by the controller and the system outputs of the quad tiltrotor model as neural network inputs to implement adaptive parameter adjustments for the Extended State Observer (ESO) component responsible for disturbance estimation and the Nonlinear State Error Feedback (NLSEF) control law of the active disturbance rejection controller. Finally, an adaptive attitude control system for the quad tiltrotor UAV is constructed, centered on the ADRC-RBF controller. Subsequently, the efficacy of the attitude control system is validated through simulation, encompassing a range of flight conditions. The simulation results demonstrate that the Integral of Absolute Error (IAE) of the pitch angle response controlled by the ADRC-RBF controller is reduced to 37.4° in comparison to the ADRC controller in the absence of external disturbance in the full-states mode state of the quad tiltrotor UAV, and the oscillation amplitude of the pitch angle response controlled by the ADRC-RBF controller is generally reduced by approximately 50% in comparison to the ADRC controller in the presence of external disturbance. In comparison with the conventional ADRC controller, the proposed ADRC-RBF controller demonstrates superior performance with regard to anti-disturbance capability, adaptability, and tracking accuracy.

In order to improve the grid-connected stability of wind power grid-connected inverter, solve the harmonic and resonance problems encountered at the grid-connected interface of inverter when the load jumps. An improved linear active disturbance rejection control strategy combined with active damping (ILADRC-AD) is designed. Firstly, the mathematical model of inductance-capacitance-inductance (LCL) inverter is established, and the principle of traditional third order active disturbance rejection controller is analyzed. Based on the idea of lead correction, an improved LADRC is designed by series lead correction links on the total disturbance channel of the linear extended state observer (LESO). Capacitive current feedback active damping is introduced in combination with improved LADRC to generate an ILADRC-AD control strategy. The stability and robustness of the system are effectively improved. Finally, the frequency characteristics of the ILADRC-AD inverter system are analyzed by frequency domain analysis method, and the MATLAB simulation comparison of improved control and traditional PI and LADRC the grid current waveform. The results show that the improved control not only has more stable grid-connected current, but also has fast dynamic response and strong harmonic suppression when the load fluctuates.

Quadrotor trajectory tracking and obstacle avoidance by chaotic grey wolf optimization-based active disturbance rejection control

To address the challenges of accurately modeling the motion of deep-sea aquaculture vessels under the combined effects of dynamic disturbances from the external environment and coupled disturbances from the liquid levels within the aquaculture tanks, as well as the performance limitations of traditional Active Disturbance Rejection Control (ADRC), this study proposes an improved Active Disturbance Rejection Control strategy based on the ADRC structure, and applies it to the design of the controller for the dynamic positioning system of aquaculture vessels. Furthermore, to tackle the issues of numerous uncertain parameters and tuning difficulties inherent in ADRC, an Improved Whale Optimization Algorithm (IWOA) is introduced for parameter tuning. The optimization algorithm incorporates a chaotic optimization strategy and an improved adaptive inertia weight ω with nonlinear characteristics, which simplifies the complex process of constructing an adaptive function in the Grey Wolf Optimization (GWO) algorithm and addresses the slow global search speed and poor local optimization ability of the traditional Whale Optimization Algorithm (WOA). The final Simulink simulation results demonstrate that the ADRC controller designed with IWOA outperforms traditional WOA, GWO, and Genetic Algorithm-optimized ADRC controllers in terms of control effectiveness and disturbance rejection capability, improved the dynamic positioning control performance of aquaculture vessels.