Disturbance Rejection Research Articles

Cooperative Active Disturbance Rejection Control for Heavy-Haul Trains

Cooperative control of multiple heavy-haul trains can improve the safety and efficiency of heavy-haul railway transportation. However, the influence of internal and external unknown disturbances for multiple heavy-haul trains is a serious obstacle, which will lead to imprecise train operation control. To address this issue, a cooperative active disturbance rejection control for heavy-haul trains is proposed. First, a multi-mass point longitudinal dynamic model of heavy-haul trains is established to meet the actual operation. Second, a cooperative active disturbance rejection controller is designed to estimate and compensate for the disturbance caused by the interaction between the trains and environment. Moreover, the extended state observer is leverage to estimate the nonlinear disturbance online, which enhances the resistance of multiple heavy-haul trains to nonlinear time-varying disturbance and suppresses the overshoots of train velocities and inter-train distance. Finally, the performance of the proposed method is verified in two different simulation scenarios: acceleration and deceleration conditions. The simulation results show that the proposed method reduces the maximum relative displacement by 38.9% and the velocity error by 54.5%.

Dynamic Decoupled Current Control for Smooth Torque of the Open-Winding Variable Flux Reluctance Motor Using Integrated Torque Harmonic Extended State Observer

Variable Flux Reluctance Machines (VFRMs) face multiple interconnected challenges that limit their performance, particularly in high-performance applications such as electric vehicles (EVs), where smooth torque output and robust operation are critical. Chief among these challenges are complex inter-axis couplings, including cross-coupling in the dq-axis, differential term coupling in the d0-axis, and disturbances propagating from the 0-axis to the q-axis. Additionally, harmonic disturbances associated with torque ripple exacerbate performance issues, resulting in degraded dynamic behavior. These challenges hinder current loop controllers, preventing effective management of winding impedance voltage drops and inter-axis coupling terms without advanced decoupling strategies. To address these challenges, this paper proposes a novel integrated torque harmonic extended state observer (ITHESO) within a decoupled current control designed to ensure fast and accurate current tracking, system stability, and torque ripple reduction. The ITHESO identifies and compensates for total current disturbances, including harmonic components, through feed-forward compensation within the current loop. Furthermore, the influence of control parameters and the effects of parameter mismatches on stability, torque ripple reduction, and disturbance rejection are thoroughly analyzed. Experimental validations demonstrate that the proposed strategy significantly enhances torque dynamics and reduces torque ripple, outperforming the conventional Active Disturbance Rejection Control (ADRC), which does not explicitly address disturbances associated with torque ripple. These advancements position the VFRM with the ITHESO as a competitive option for high-performance EV propulsion systems, offering smooth operation, noise reduction, and reliable performance under varying speeds and loads.

Active disturbance rejection control for reducing vehicle body displacement based on an extended state observer and dynamic fuzzy techniques

Active disturbance rejection control for reducing vehicle body displacement based on an extended state observer and dynamic fuzzy techniques

Fault-tolerant consensus control of linear multi-agent systems with polynomial faults based on event triggered mechanism

This paper investigates the problem of fault-tolerant consensus control in multi-agent systems, with an emphasis on triggers induced by polynomial faults. Polynomial models are utilized to precisely capture the diverse range of faults that may manifest within the system, enabling an accurate representation of fault dynamics through polynomial approximations. An observer is subsequently designed to estimate both system faults and external disturbances with a high degree of accuracy. To optimize communication efficiency, an event-triggering mechanism based on periodic sampling is introduced, significantly reducing superfluous data transmissions. Based on the estimated faults and disturbances, a distributed fault-tolerant controller is devised. This controller effectively mitigates the impact of actuator faults while attenuating external disturbances, thereby substantially enhancing system robustness. The proposed approach ensures synchronization, disturbance rejection, and robust consensus control throughout the multi-agent network. The efficacy of the proposed methods is demonstrated through extensive simulation studies. Moreover, the approach not only decreases the frequency of event triggers but also enlarges the domain of attraction. The practical feasibility and effectiveness of the approach are further validated through two comprehensive simulation examples.

A Robust Linear Active Disturbance Rejection Control for Renewable Energy Grid-Connected System Based on APF

With the energy transition and changes in electrical load structures, harmonic distortion in power systems is increasingly threatening grid stability, especially during the integration of renewable energy sources. Active power filters (APFs) are commonly used to improve power quality, but current fluctuations and voltage instability caused by DC-side capacitor charging and discharging hinder effective harmonic compensation. To address this, this paper presents a method combining a variable-step-size adaptive linear predictor with linear active disturbance rejection control (VALP-LADRC). By integrating an adaptive linear predictor (ALP) with LADRC, the proposed method effectively reduces the impact of disturbances on control, improving voltage regulation and harmonic compensation, and enhancing renewable energy grid integration. To address delays during the adjustment of initial parameters in the adaptive predictor, we combine it with a variable-step-size algorithm, significantly improving disturbance rejection and tracking accuracy, while solving voltage drop issues. The simulation results in a photovoltaic grid-connected system show that VALP-LADRC effectively mitigates disturbances, ensures voltage stability, and enhances power quality. This approach offers a promising solution for supporting sustainable development through better renewable energy integration and improved power quality.

Active Disturbance Rejection Control for an automotive suspension system based on parameter tuning using a fuzzy technique.

Road surface roughness is the cause of vehicle vibration, which is considered a system disturbance. Previous studies on suspension system control often ignore the influence of disturbances while designing the controller, leading to system performance degradation under severe vibration conditions. In this work, we propose a control method to improve active suspension performance that reduces vehicle vibration by eliminating the influence of road disturbances. The proposed method is formed based on the combination of an Active Disturbance Rejection Control (ADRC) technique with control coefficients tuned by a dynamic fuzzy technique formed based on special membership functions called Active Disturbance Rejection Control Based on Fuzzy (ADRCBF). An Extended State Observer (ESO) estimates state variables and disturbances. The performance of the proposed controller is evaluated through the numerical simulation process with three different cases. According to the calculation results, the acceleration and displacement of the sprung mass are significantly reduced when the suspension system is controlled by the proposed technique, compared with the passive suspension system and the active suspension system controlled by a Proportional-Integral-Derivative (PID) technique. In addition, the suspension travel follows the road disturbance with a small error. The error estimated by the ESO does not exceed 3.5% (for sinusoidal and random excitation). In general, system adaptation is ensured under many investigated conditions based on tuning the controller parameters by the soft computing method.

Modeling and control of a sperm-inspired robot with helical propulsion.

Efficient propulsion has been a central focus of research in the field of biomimetic underwater vehicles. Compared to the prevalent fish-like reciprocating flapping propulsion mode, the sperm-like helical propulsion mode features higher efficiency and superior performance in high-viscosity environments. Based on the previously developed sperm-inspired robot, this paper focuses on its dynamic modeling and depth control research. The helical propulsion performance of the sperm-inspired robot is analyzed by resistance-theory-based force analysis, followed by the application of Kirchhoff rod theory to determine the helical waveform parameters. The dynamic model of the sperm-inspired robot is established using the Kirchhoff equation, and its validity is verified through experiments. To enhance the practical application capability of the sperm-inspired robot, this study develops an ADRC (Active Disturbance Rejection Control) depth controller for roll-spin coupling motion based on the constructed dynamics model. The effectiveness of the controller is thoroughly validated through a combination of simulation and experiment. Experimental results demonstrate the excellent depth control ability of the robot, with an average depth error controlled within 0.19 cm. This superior performance lays a foundation for the future application of our robot in underwater operations.

A Symmetry-Inspired Hierarchical Control Strategy for Preventing Rollover in Articulated Rollers

In off-road environments, the lateral rollover stability of articulated unmanned rollers (URs) is critical to ensure operational safety and efficiency. This paper introduces the concept of a rollover energy barrier (REB), a symmetry-based metric that quantifies the energy margin between the current state and the critical rollover threshold of articulated rollers. URs exhibit dynamic asymmetry due to their hydraulic steering systems, which differ significantly from traditional passenger vehicles. To address these challenges, we propose a hierarchical control framework inspired by the principles of dynamic symmetry. This framework integrates Nonlinear Model Predictive Control (NMPC) and Active Disturbance Rejection Control (ADRC): NMPC is used for trajectory planning by incorporating the REB into the cost function, ensuring rollover stability, while ADRC compensates for dynamic asymmetries, model uncertainties, and external disturbances during trajectory tracking. Simulation and experimental results validate the effectiveness of the proposed control strategy in enhancing the rollover stability and tracking performance of the URs under off-road conditions.

A New Closed-Loop Control Paradigm Based on Process Moments

The paper presents a new control concept based on the process moment instead of the process states or the process output signal. The control scheme is based on separate control of reference tracking and disturbance rejection. The tracking control is achieved by additionally feeding the input of the process model by the scaled output signal of the process model. The advantage of such feedback is that the final state of the process output can be analytically calculated and used for control instead of the actual process output value. The disturbance rejection, including model imperfections, is controlled by feeding back the filtered difference between the process output and the model output to the process input. The performance of tracking and disturbance rejection is simply controlled by two user-defined gains. Several examples have shown that the new control method provides very good and stable tracking and disturbance rejection performance.

Performance Analysis of Active Disturbance Rejection Control for Complex Articulated Ornithopter

Performance Analysis of Active Disturbance Rejection Control for Complex Articulated Ornithopter

Improved segmental active disturbance rejection control for direct-drive valve controlled hydraulic shaking table

To address the performance degradation of hydraulic shaking table under nonlinear disturbances, an improved segmental active disturbance rejection controller (IS-ADRC) based on a switching control law is designed. A self-coupling PID (SC-PID) control law is designed, and an adaptive speed factor model is proposed to enhance the system’s response speed without compromising disturbance observation ability, thus avoiding oscillations and instability caused by high-gain observer. To overcome the jitter issue in traditional nonlinear state error feedback (NLSEF) control laws, an improved control law (INLSEF) based on a smooth Fal-M function is designed to replace the traditional fal function. Moreover, considering the potential for integral saturation, a switching principle is designed to switch from the SC-PID control law to the INLSEF control law at small errors, ensuring smooth system convergence. The stability of the controller is proved using Lyapunov stability theory. Results demonstrate that the proposed IS-ADRC improves the response speed and anti-disturbance ability of the hydraulic shaking table. Furthermore, the Fal-M function effectively reduces the jitter phenomenon compared to traditional ADRC.

Quaternion-Based Fast SMC–PD Cross-Domain Tracking Control for Coaxial Hybrid Aerial–Underwater Vehicle Under Oceanic Disturbances

In this study, nonsingular modeling and cross-domain trajectory tracking control problems for a special class of coaxial hybrid aerial–underwater vehicles (HAUVs) are investigated. Coaxial HAUVs need to effectively overcome the influence of hydrodynamic factors when moving underwater, so the attitude angle required by coaxial HAUVs is much larger than that in the air. The attitude representation based on quaternion modeling is adopted to avoid the inherent singularity of Euler angle modeling. A cascade sliding mode control and proportion differentiation (SMC-PD) controller is proposed, which is used to position trajectory and attitude quaternion tracking control, respectively. An adaptive sliding mode controller based on disturbance observer (DO) enhancement is adopted in the outer loop to carry trajectory tracking control. At the same time, the expected attitude angle is calculated by the outer loop (position) and is converted into the expected quaternion. With reference to the idea of enhanced robustness in active disturbance rejection control (ADRC), a feedforward proportion derivation (PD) controller based on DO enhancement is used to track the desired quaternion. A variable parameter adaptive algorithm based on the learning rate is introduced in the cascaded SMC-PD controller. The error convergence speed of the system is further improved by adaptively changing the controller parameters. The stability of the proposed control scheme is proved by using the Lyapunov theory. The numerical simulation results show that the controller has good robustness and effectiveness.

Model-Free Speed Control for Pumping Kite Generator Systems Based on Nonlinear Hyperbolic Tangent Tracking Differentiator

This paper investigates the emerging field of grid-connected wind-powered pumping kite generator system (PKGS), focusing on the challenges associated with the generator/motor speed control. Conventional use of proportional–integral (PI) controllers faces difficulties in meeting requirements for dynamic response, tracking performance, stability, and disturbance rejection encountered in this technology, notably the periodical variation in the rotational speed reference in maximum power point tracking in generation phases and the dynamic response for the step reference in transient ones. To overcome these limitations, a model-free controller (MFC) approach is introduced, also known as intelligent PID controllers. Unlike traditional methods, MFC does not rely on a control model of the system and adapts to uncertainties and disturbances through online estimation based on the system’s input–output behavior. To further improve the control performances, a tracking differentiator based on a nonlinear hyperbolic tangent function is integrated in the MFC. The effectiveness of the proposed strategy is proved through simulations in MATLAB/Simulink. The results highlight the superior performances of the proposed MFC approach in terms of speed control accuracy, response time, and robustness.

Design and experimental study of tillage depth control system for electric rotary tiller based on LADRC

This paper proposes an adaptive real-time tillage depth control system for electric rotary tillers, based on Linear Active Disturbance Rejection Control (LADRC), to improve tillage depth accuracy in tea garden intercropping with soybeans. The tillage depth control system comprises a body posture sensor, a control unit, and a hybrid stepper motor, integrating sensor data to drive the motor and achieve precise depth control. Real-time displacement sensor signals are compared with target values, enabling closed-loop control of the rotary tiller. Field experiments conducted at 0.5 km/h and 0.8 km/h, with preset tillage depths of 80 mm and 100 mm, demonstrated the system’s effectiveness. The average standard deviation of tillage depth for the LADRC system was 3.2 mm, compared to 10.5 mm for fuzzy proportional-integral-derivative (PID) control. The LADRC control reduced the rate of change in tillage depth by 68.9% compared to fuzzy PID. This system effectively mitigates potential deviations during operation, ensuring stable and reliable tillage depth control.

A double closed loop digital hydraulic cylinder position system based on switching active disturbance rejection control

A switching active disturbance rejection control (SADRC) strategy was proposed to solve the composite disturbance challenge arising from gap, LuGre friction, hydraulic spring force, and external load disturbance in the double closed-loop digital hydraulic cylinder position control system. Firstly, leveraging the established mathematical model of the double closed-loop digital hydraulic cylinder, the high-order state equation was derived. Subsequently, the high-order double closed-loop digital hydraulic cylinder control system was transformed into a second-order integral series control system using ADRC strategy. Given the pronounced nonlinear characteristics of double closed-loop digital hydraulic cylinders, combined with the characteristics of switching control, a SADRC strategy was proposed, and the stability of the closed-loop system was proved based on Lyapunov theory and switching rules. Finally, the effectiveness of the proposed control method was verified through simulation and experiment. Results indicate that the system's response speed employing the SADRC strategy outperforms the PID control strategy by 32.56%, with a 2.0% reduction in error. The average error in the response speed of the digital hydraulic cylinder and the MATLAB simulation value of the tracking error are 9.0% and 1.50% respectively. Notably, the simulation and experimental results exhibit a consistent overall trend, affirming the feasibility and effectiveness of the control strategy.

Fractional-Order Sliding Mode with Active Disturbance Rejection Control for UAVs

Fractional-Order Sliding Mode with Active Disturbance Rejection Control for UAVs

VSDRL: A robust and accurate unmanned aerial vehicle autonomous landing scheme

AbstractVisually assisted unmanned aerial vehicle (UAV) autonomous landing has drawn a lot of interest as a vital technology with the quick development of UAV systems. From the perspective of robustness, a visual servoing disturbance rejection landing (VSDRL) scheme based on fractional‐order linear active disturbance rejection control is novelly proposed to achieve the disturbance‐resistant landing. The proposed VSDRL scheme is constructed by two modules: (i) A visual positioning algorithm combining YOLOv5 with Kalman filtering to solve the occlusion problem in the visual positioning module obtaining the relative position relationship; (ii) On the basis of linear active disturbance rejection control, fractional order is introduced to improve the antidisturbance ability and response speed. Theoretical analysis, computer simulations and real UAV experiments all verify the effectiveness and superiority of the proposed VSDRL scheme.

Design of Cascade Equivalent-Input-Disturbance Estimator for Control System Under High-Frequency Noise.

This article presents a cascade equivalent-input-disturbance (EID) estimator to handle the control problem of disturbance rejection in the presence of measurement noise. The standard EID estimator faces a challenge when the output of a system suffers from high-frequency noise, i.e., the estimator tuned to achieve high disturbance-rejection performance is usually extremely sensitive to measurement noise. A new estimator is developed in this study to address the issue by combining EID estimators in a unique cascade form. The sensitivity reduction of a cascade EID (CEID) estimator with p levels, which is related to disturbance rejection, is p times larger than that of a standard EID estimator at low frequencies. Meanwhile, the Bode magnitude curve of the transfer function related to noise suppression is shifted up only by 20lgp dB at high frequencies compared to that of a standard one. This improves disturbance-rejection performance and prevents measurement noise from being over-amplified. The design of a CEID estimator-based control system is provided and the stability criterion of the system is derived. The validity and superiority of the presented method are demonstrated by a deep analysis and simulation and experimental results.

Harmonics and Disturbance Rejection in Optoelectronic Tracking and Measuring Systems Using Trigger Resonant and Robust Current Controller With Cascaded Two-Degrees-of-Freedom Structure

Harmonics and Disturbance Rejection in Optoelectronic Tracking and Measuring Systems Using Trigger Resonant and Robust Current Controller With Cascaded Two-Degrees-of-Freedom Structure

A rule of robust optimal parameter tuning of Active Disturbance Rejection Control based on second order plus dead time model approximation

A rule of robust optimal parameter tuning of Active Disturbance Rejection Control based on second order plus dead time model approximation