Strong Disturbance Rejection Ability Research Articles

Research on morphing aircraft maneuver control based on active disturbance rejection control

Aiming at the problems of model uncertainties caused by morphing aircraft during morphing process and disturbance encountered when maneuvering, a morphing aircraft maneuver control method based on active disturbance rejection control (ADRC) is proposed to eliminate the influences of model uncertainty and external disturbance and improve the rapidity and accuracy of maneuver control. Firstly, a nonlinear model for morphing aircraft is established and the impact mechanism of morphing process is analyzed. Then, the ADRC technique is used to design the angular rate robust control law and the control performance of ADRC law is analyzed under the influence of disturbance. Finally, the immelmann turn maneuver is selected to verify the performance of the designed control law with aerodynamic parameters perturbation combined with the morphing process. The simulation results show that the method possesses good decoupling effect and strong disturbance rejection ability. Moreover, the aircraft's maneuverability and the control margin of control surface can be effectively improved through morphing

Nonlinear Extended State Observer Based Super-Twisting Terminal Sliding Mode Synchronous Control for Parallel Drive Systems

Addressing the issue to restrain the nonlinear coupling disturbance in the multimotor parallel drive system and acquiring perfect driving control performance, a novel super-twisting terminal sliding mode synchronous control (STSC) is proposed. In this control scheme, a lumped error (LE) with a synchronization coefficient is designed to transform coupled control into LE convergence. Then, a recursive terminal sliding mode function with two layers is introduced. Based on this sliding mode function, the STSC scheme is proposed, and it can guarantee the LE finite-time convergence and the continuous control action in nature. A nonlinear extended state observer (NESO) is introduced to enhance robustness. Moreover, the NESO not only provides an estimation of disturbance but also provides a smooth velocity signal. Therefore, differential operations and filtering operations are avoided. Finally, a compound control scheme is obtained. Compared with conventional super-twisting algorithm (STA), the robustness is enhanced by embedding NESO-based disturbance compensation, and the advantage of continuous control action is inherited. The major advantages of this scheme are characterized by output-based information only used, good model adaptability, and strong disturbance rejection ability. Experimental results show the effectiveness of the proposed control law.

Global Finite-Time Stabilization of Spacecraft Attitude With Disturbances via Continuous Nonlinear Controller

In this paper, a robust continuous controller is investigated to solve the global finite-time attitude stabilization problem of rigid spacecraft system subject to multiple disturbances. The system order is firstly increased by derivation and the derivative of the actual torque is regarded as the virtual control law to be designed. Then, a super-twisting differentiator is constructed to provide finite-time angular acceleration estimations. Finally, based on the estimated angular accelerations, a discontinuous set stabilization control law is designed as the virtual controller. The actual continuous controller is obtained by integrating the discontinuous one. Rigorous proof and stability analysis are presented based on Lyapunov analysis. Compared with most of the existing finite-time control approaches in spacecraft systems, the proposed continuous control scheme guarantees the finite-time set stability of the closed-loop system. Moreover, the system states can converge to the equilibria even in the presence of derivative-bounded disturbances. Simulation studies of the proposed controller are illustrated to demonstrate the strong disturbance rejection ability, fast convergence rate, and high steady-state precision.

Rotating mirror servo system control based on modified sliding mode-active disturbance rejection controller

In order to improve the tracking accuracy and robustness of the rotating mirror servo system, a modified sliding mode-active disturbance rejection control (MSM-ADRC) strategy is proposed. Firstly, the structure and working principle of the rotating mirror servo system are analysed, and its mathematical model is established to prepare for the design of the controller. Then, a MSM-ADRC is proposed to reduce the influence of unknown disturbance and improve the tracking accuracy. Among them, the modified sliding mode extended state observation (MSM-ESO) is designed by replacing the traditional nonlinear function with the designed optimal control function, which enhances the observation accuracy of the system state quantity and total disturbance. Meanwhile, an improved approach law is proposed, and an improved sliding mode nonlinear error feedback control law (MSM-NLSEF) is designed based on this approach law, which improves the convergence speed and accuracy of the control law. In addition, the stability of the designed MSM-ESO and MSM-NLSEF is proved. Finally, the proposed control method is validated by simulation and experimental comparison with other state-of-the-art controllers. Results reveal that the proposed control method has satisfying tracking performance and strong disturbance rejection ability.

Dual-Loop Dynamic Control of Cable-Driven Parallel Robots Without Online Tension Distribution

Achieving high-precision position control while maintaining positive cable tensions is the most challenging issue for the motion control of cable-driven parallel robots, which should be considered significantly. Different from the existing control schemes with online tension distribution that needs real-time computing in each control cycle, a novel dual-loop dynamic control scheme is proposed in this article, where a paralleled dual-loop tracking strategy is introduced to provide a more compatible scheme, which consists of two tracking loops: 1) the tension control loop and 2) the position control loop. In the former loop, the offline tension distribution is adopted to avoid cable hanging loosely and the real-time feasibility of the distribution method is no longer a necessary demand. In the latter loop, due to the complex dynamics characterized by the cable-driven form, the cooperative motion relation among multiple cables and inevitable external disturbances are investigated comprehensively, and the robust synchronization method is included to guarantee the high-precision position control. Afterward, the Lyapunov method is adopted to analyze the strict stability of the whole closed-loop system with both the position and tension control feedback. The experiments indicate that by synthesizing the two control loops, the proposed scheme can dramatically reduce the tracking errors in the trajectory tracking while avoiding the cable relaxation, and particularly, has a satisfactory control effect when the velocity and acceleration of the trajectory have significant oscillations. Additionally, the strong disturbance rejection ability is also validated via robustness experiments.

Quadrotor Attitude Control by Fractional-Order Fuzzy Particle Swarm Optimization-Based Active Disturbance Rejection Control

In this paper, Active Disturbance Rejection Control (ADRC) is utilized in the attitude control of a quadrotor aircraft to address the problem of attitude destabilization in flight control caused by parameter uncertainties and external disturbances. Considering the difficulty of optimizing the parameter of ADRC, a fractional-order fuzzy particle swarm optimization (FOFPSO) algorithm is proposed to optimize the parameters of ADRC for quadrotor aircraft. Simultaneously, the simulation experiment is designed, which compares with the optimized performance of traditional particle swarm optimization (PSO), fuzzy article swarm optimization (FPSO) and adaptive genetic algorithm-particle swarm optimization (AGA-PSO). In addition, the turbulent wind field model is established to verify the disturbance rejection performance of the controller. Finally, the designed controller is deployed to the actual hardware platform by using the model-based design method. The results show that the controller has a small overshoot and stronger disturbance rejection ability after the parameters are optimized by the proposed algorithm.

Research on Compound Sliding Mode Control of a Permanent Magnet Synchronous Motor in Electromechanical Actuators

In order to improve the response speed and disturbance rejection ability of a permanent magnet synchronous motor (PMSM) in an electromechanical actuator (EMA), a compound sliding mode control (CSMC) is proposed. The CSMC consists of a sliding mode controller with a new reaching law and disturbance observer based on a symmetric S-type function. The stability of the CSMC is analyzed using the Lyapunov stability analysis. The effectiveness of the CSMC is confirmed by the Simulink simulation, and experiments were conducted on a semi-physical platform. The results obtained by comparing the CSMC with the proportional integral (PI) control and traditional sliding mode control show that the CSMC has a faster response and stronger disturbance rejection ability and reduces chattering.

A DPS-PLL based rotor position estimation method for permanent magnet wind turbine

Aiming at the problem of slow response and low tracking accuracy in the synchronous reference frame phase-locked loop (SRF-PLL) estimation of the permanent magnet synchronous generator (PMSG) rotor position when the wind speed changes suddenly, a rotor position estimation method based on the discrete position set phase-locked loop(DPS-PLL) is proposed. The estimated position in certain moment is selected from a discretized alternative position set. Then, combined with sliding mode observer, rotor position is obtained by calculating back-EMF cost function. The experimental results demonstrate the rotor position and speed can be detected accurately under sudden change of wind speed. The convergence time of estimation is within 42 ms. The estimated error of rotor position is less than 0.03 rad. The results show that the proposed method provides a satisfactory dynamic performance and strong disturbance rejection ability.

Continuous dynamic gain scheduling control for input-saturated switched systems

In this paper, we proposed a continuous dynamic gain scheduling control for the input-saturated switched system. The state feedback controller and the compensator-based output feedback controller are both designed based on the parametric Lyapunov equation, sliding mode control and gain scheduling control. The advantages of the proposed methods are improving the dynamic performance of the switched system, guaranteeing the exponential stability of the closed-loop system and the proposed method has stronger disturbance rejection ability. The designed controllers can be computed by solving the parametric Lyapunov equation. The numerical simulations are carried out to illustrate the usefulness of the proposed methods.

Disturbance rejection sliding mode control for robots and learning design

The control of a robot to achieve both good dynamic and static performance against external disturbances is a challenging task, especially when high speed and a wide range of motion is required. In this paper, a disturbance rejection sliding mode control (SMC) methodology is designed for a robot manipulator. This methodology synthesizes the SMC design with the active disturbance rejection control (ADRC) technique. An extended state observer is employed to estimate unknown disturbances, which is difficult to deal with in a conventional SMC design, and to simplify the SMC law design. A learning-based parameter tuning methodology is presented to autonomously obtain the control parameters offline. To develop a robust and transferring controller, a neural network is used to learn the joint actuation ability for the controller optimizing process. Compared with other state-of-the-art controllers, both numerical simulations and experiments of a 6-DOF robot are provided to demonstrate the proposed control method and design methodology. These results reveal that the proposed control method has a satisfying tracking performance and strong disturbance rejection ability.

Research on load simulation control system based on optimal H∞ method

In order to optimize the accuracy of the vehicle load simulation system, the control framework of the system is established based on the speed tracking method. Based on H∞ mixed sensitivity method, a disturbance observer is established. In order to solve the problem that the order of disturbance observer is too high to restrain disturbance directly, a design constraint framework of disturbance observer is proposed, and the optimization of disturbance observer is realized in the constraint framework. The simulation and experimental results show that the optimized disturbance observer has stronger disturbance rejection ability.

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

Second-order plus dead-time systems are difficult to tune for a PID controller due to its special structure, especially the underdamped systems that have oscillatory responses. As a control technique with strong disturbance rejection ability, linear active disturbance rejection control is widely used as a substitute for PID controllers. This paper proposes a tuning formula for second-order linear active disturbance rejection control for underdamped second-order plus dead-time systems via internal model control. The formula is derived by minimizing the integral of time squared error index under certain robustness measure condition. Simulation results show that the linear active disturbance rejection controller tuned from the proposed formula can achieve satisfactory control performance for oscillatory systems.

Dynamic Performance Enhancement Method Based on Improved Model Reference Adaptive System for SPMSM Sensorless Drives

Conventional sensorless drives usually suffer from an unsatisfactory dynamic response to the varying speed reference or load disturbance due to the design only for the speed estimator. In this paper, an improved adaptive law based model reference adaptive system (IAL-MRAS) algorithm is proposed to enhance the dynamic performance of a surface-mounted permanent magnet synchronous motor (SPMSM) sensorless drives, in which both a speed/position estimator and composite speed controller are designed by a systematic way. This improved adaptive law (IAL) incorporates both the mechanical and electromagnetic model to account for the mechanical factors on the speed variation, which can estimate the rotor position and load torque simultaneously. To further strengthen the disturbance rejection ability, a composite speed controller is designed based on the feedforward compensation scheme and IAL-MRAS. Meanwhile, a hybrid control strategy combining IAL-MRAS and $I$ - $f$ starting method is adopted to realize sensorless control in the full speed range. Comprehensive numerical simulation and experimental results have fully demonstrated that the proposed sensorless control strategy can achieve smaller settling time, stronger disturbance rejection ability, and less parameter tuning workload than those of the conventional methods.

Active disturbance rejection sliding mode control for robot manipulation

PurposeIn recent years, owing to the rapidly increasing labor costs, the demand for robots in daily services and industrial operations has been increased significantly. For further applications and human–robot interaction in an unstructured open environment, fast and accurate tracking and strong disturbance rejection ability are required. However, utilizing a conventional controller can make it difficult for the robot to meet these demands, and when a robot is required to perform at a high-speed and large range of motion, conventional controllers may not perform effectively or even lead to the instability.Design/methodology/approachThe main idea is to develop the control law by combining the SMC feedback with the ADRC control architecture to improve the robustness and control quality of a conventional SMC controller. The problem is formulated and solved in the framework of ADRC. For better estimation and control performance, a generalized proportional integral observer (GPIO) technique is employed to estimate and compensate for unmodeled dynamics and other unknown time-varying disturbances. And benefiting from the usage of GPIO, a new SMC law can be designed by synthesizing the estimation and its history.FindingsThe employed methodology introduced a significant improvement in handling the uncertainties of the system parameters without compromising the nominal system control quality and intuitiveness of the conventional ADRC design. First, the proposed method combines the advantages of the ADRC and SMC method, which achieved the best tracking performance among these controllers. Second, the proposed controller is sufficiently robust to various disturbances and results in smaller tracking errors. Third, the proposed control method is insensitive to control parameters which indicates a good application potential.Originality/valueHigh-performance robot tracking control is the basis for further robot applications in open environments and human–robot interfaces, which require high tracking accuracy and strong disturbance rejection. However, both the varied dynamics of the system and rapidly changing nonlinear coupling characteristic significantly increase the control difficulty. The proposed method gives a new replacement of PID controller in robot systems, which does not require an accurate dynamic system model, is insensitive to control parameters and can perform promisingly for response rapidity and steady-state accuracy, as well as in the presence of strong unknown disturbances.

Position Control with ADRC for a Hydrostatic Double-Cylinder Actuator

A compact and flexible hydraulic double-cylinder actuation scheme is proposed for use in applications, especially where power density is extremely demanding. In view of flexible amounting requirements, long and thin hoses were utilized to connect two cylinders. Affecting the actuation preciseness, volume variation of the hoses caused by pressurized oil and bubbles was the main problem the system encountered. In this study, an active disturbance rejection control (ADRC) strategy was adopted for the improvement of displacement control performance under uncertain external load. After the experimental verification of the necessity of a hose model for the system, a centralized-parameter hose model was constructed where the coefficients are determined on the basis of the experimental data. Additionally, the system and the controller proposed were mathematically modeled. Simulation results shows that the system using ADRC exhibited higher displacement accuracy and better dynamic performance than that using PID (Proportion-Integral-Derivative) or fuzzy PID. ADRC has a stronger disturbance rejection ability. ADRC is an effective solution to nonlinear control of systems with uncertain parameters or various loads.

Attitude trajectory planning and attitude control for quad-rotor aircraft based on finite-time control technique

Abstract The attitude control problem for quad-rotor spacecraft is investigated in this paper. Considering the yaw dynamical rate is slower than that of roll and pitch channel, firstly, we establish the attitude trajectory and then propose an attitude decoupled control strategy. For the specific attitude controller design, we design a finite-time attitude tracking controller based on the finite-time control technology. The rigorous stability analysis method based on homogeneous system theory is given, which proves that spacecraft attitude can reach the expected attitude in a finite time. Experimental results on a real quad-rotor platform show that the proposed control strategy has the advantages of convergence and strong disturbance rejection ability.

Finite-time path following control for small-scale fixed-wing UAVs under wind disturbances

By integrating the finite time control technique and finite-time disturbance observers together, the finite-time three-dimensional path following control problem for small-scale fixed-wing UAVs subject to external wind disturbances is investigated in this paper. The external wind disturbances are estimated through finite-time disturbance observers and the estimates are then incorporated into the finite-time feedback controller such that a composite control scheme is proposed. Under the proposed control scheme, the closed-loop system possesses not only faster convergence rate but also stronger disturbance rejection ability and better robustness, which is the main contribution of the paper. The effectiveness and superiorities of the proposed composite control scheme are demonstrated by numerical simulations.

Fuzzy Terminal Sliding Mode Control with Compound Reaching Law and Time Delay Estimation for HDU of Legged Robot

Hydraulic drive mode enables legged robots to have excellent characteristics, such as greater power-to-weight ratios, higher load capacities, and faster response speeds than other robots. Nowadays, highly integrated valve-controlled cylinder, called the hydraulic drive unit (HDU), is employed to drive the joints of these robots. However, there are some common problems in the HDU resulted from hydraulic systems, such as strong nonlinearity, asymmetry dynamic characteristics between positive and negative moving directions of the piston rod, and time-varying parameters. It is difficult to obtain the desired control performance by just using classical control methods such as the traditional PID control. In this paper, a position controller that combines fuzzy terminal sliding mode control (FTSMC) and time delay estimation (TDE) is proposed, in which FTSMC adopts a compound reaching law which combines the tangent function and the exponential reaching law. Moreover, the fuzzy control is introduced to adjust the parameters of the reaching law in real time to improve the adaptability of FTSMC. Based on FTSMC, the external uncertain disturbance of the HDU position control system is estimated by TDE, which ensures the simplicity of system modeling and the normal application of FTSMC. Finally, the control effects of the controller combining FTSMC and TDE are verified on the HDU performance test platform and the load simulation experiment platform. The experimental results show that the proposed controller greatly improves the system position control performance and has a strong disturbance rejection ability and a good adaptability under different working conditions. The above research results can provide an important reference and experimental basis for the inner loop of compliance control of legged robots.

Finite-time active disturbance rejection control for marine diesel engine

Abstract In order to handle the non-linear system and the complex disturbance in marine engines, a finite-time convergence active disturbance rejection control (ADRC) technique is developed for the control of engine speed. First, a model for the relationship between engine speed and fuel injection is established on the basis of the mean value engine model. Then, to deal with the load disturbances and model parameter perturbation of the diesel engine, this paper designs an ADRC approach to achieve finite-time stability. Finally, simulation experiments show that the proposed method has better control effect and stronger disturbance rejection ability in comparison with the standard linear ADRC.

Adaptive LADRC-Based Disturbance Rejection Method for Electromechanical Servo System

Electromechanical actuator (EMA) exhibits advanced performance in industry, but its dynamic servo responses are constrained by parametric perturbations, load torque variations, and measurement noise. A strong disturbance rejection ability is necessary for EMAs. However, this usually makes them more sensitive to the measurement noise, reducing the steady-state precision. In this article, an adaptive linear active disturbance rejection control (LADRC) controller is proposed to achieve strong antidisturbance performance and reduce noise sensitivity for EMAs. A novel parallel structure is proposed to improve dynamic responses, which replaces the traditional cascade structure of position and speed loops. Aiming to improve the antidisturbance performance, a linear full-order-extended state observer is integrated with the parallel controller, called the LADRC controller. To reduce the difficulty of parameter tuning, the number of tuning parameters of LADRC is reduced to two by a pole placement design. And these two parameters of LADRC can be adjusted adaptively by the hyperbolic tangent function. Finally, the simulation and experimental results are provided to verify the effectiveness of the proposed strategy for EMAs.