On performance analysis of ADRC for a class of MIMO lower-triangular nonlinear uncertain systems

This paper designs the active disturbance rejection control (ADRC) to achieve desired performance for a class of MIMO lower-triangular nonlinear systems with large uncertainties under un-matched condition. We develop the ADRC with a set of extended state observers, and prove that the closed-loop system can achieve satisfied dynamic performance. The theoretical results illustrate the relationship between the bound of the concerned error and the bandwidth of extend state observers.     

Enhanced disturbance rejection for open-loop unstable process with time delay

The present study suggests a disturbance estimator design method for application to a recently published, two-degree-of-freedom, control scheme for open-loop, unstable processes with time delay. A simple PID controller cascaded with a lead-lag filter replaces the high-order disturbance estimator for enhanced performance. A new analytical method on the basis of the IMC design principle, featuring only one user-defined tuning parameter, is developed for the design of the disturbance estimator. Several illustrative examples taken from previous works are included to demonstrate the superiority of the proposed disturbance estimator. The results confirm the superior performance of the proposed disturbance estimator in both nominal and robust cases. The proposed method also offers several important advantages for industrial process engineers: it covers several classes of unstable process with time delay in a unified manner, and is simple and easy to design and tune.     

基于死区补偿的电液位置伺服系统自抗扰控制

针对电液位置伺服控制系统的比例阀死区、参数不确定及外部未知扰动等问题,设计了由自抗扰控制器与死区逆补偿构成的串联控制器.首先基于实验辨识构造死区逆模型对死区进行预补偿,然后根据系统特性设计了一阶自抗扰控制器,构造改进的扩张状态观测器对"总扰动"进行实时估计,并通过非线性控制律给予主动补偿.联合仿真与试验结果表明,所提出...     

基于自抗扰控制的自动泊车路径跟踪

建立了基于电动助力转向系统的自动泊车系统动力学模型,考虑汽车动力学约束及泊车防碰撞约束,基于两段弧规划路径,使用反正切函数来拟合路径;应用非时间参考的路径跟踪控制策略生成目标转角,采用自抗扰控制（ADRC）方法进行转角跟踪,并通过硬件在环试验进行验证。结果表明,反正切函数拟合的路径曲率连续无突变,非时间参考的路径跟踪效果较好;所提出的ADRC转角跟踪算法比PID控制具有更高的泊车精度和响应速度。     

Discrete-time domain two-degree-of-freedom control design for integrating and unstable processes with time delay

A discrete-time domain two-degree-of-freedom (2DOF) design method is proposed for integrating and unstable processes with time delay. Based on a 2DOF control structure recently developed, a controller is analytically designed in terms of the H₂ optimal control performance specification for the set-point tracking, and another controller is derived by proposing the desired closed-loop transfer function for load disturbance rejection. Both controllers can be tuned relatively independent to realize control optimization. Analytical expression of the set-point response is given for quantitatively tuning the single adjustable parameter in the set-point tracking controller. At the meantime, sufficient and necessary conditions for holding robust stability of the closed-loop control system are established for tuning another adjustable parameter in the disturbance rejection controller, along with numerical tuning guidelines. Illustrative examples from the literature are used to demonstrate the effectiveness of the proposed method.     

交流伺服系统分数阶PID改进型自抗扰控制

针对采用永磁同步电机驱动的火箭炮交流伺服系统存在摩擦、惯性力矩、变负载及不同工况下内外扰动等复杂非线性问题,考虑到自抗扰控制(ADRC)抗内外干扰能力强和分数阶PID控制动态性能好,设计了一种分数阶PID改进型自抗扰控制器(FOPID-IADRC)。为了取得良好的动态性能和减少参数计算量,采用分数阶PID控制器取代非线性状态误差反馈器;引入粒子群优化算法,对FOPID控制器的5个控制参数进行实时在线自整定。仿真和半实物台架实验结果表明：该控制策略能够有效抑制位置扰动,具有良好的动态性能和较强的抗干扰能力。     

Simplified filtered Smith predictor for MIMO processes with multiple time delays

This paper proposes a simplified tuning strategy for the multivariable filtered Smith predictor. It is shown that offset-free control can be achieved with step references and disturbances regardless of the poles of the primary controller, i.e., integral action is not explicitly required. This strategy reduces the number of design parameters and simplifies tuning procedure because the implicit integrative poles are not considered for design purposes. The simplified approach can be used to design continuous-time or discrete-time controllers. Three case studies are used to illustrate the advantages of the proposed strategy if compared with the standard approach, which is based on the explicit integrative action.     

基于自抗扰控制的无刷直流电机换相转矩脉动抑制的研究

针对无刷直流电机在运动中会产生转矩脉动且转矩脉动会影响无刷直流电机运行的稳定性和可靠性的问题,结合现代控制理论,研究了无刷直流电机的数学模型,设计了一种基于自抗扰控制器的无刷直流电机换相转矩脉动抑制的方法。通过降低无刷直流电机的转矩脉动并且结合DSP高速运算处理器实现了其算法的控制,更好地提高了其稳态性能。采用自抗扰控制技术对无刷直流电机的换相转矩脉动进行了抑制。通过消除转速响应的超调,扩张状态观测器检测系统的相电流脉动以及用非线性状态反馈控制率对检测到的电流脉动误差值进行补偿抵消,以达到了抑制相电流脉动的效果,从而抑制了转矩的脉动。通过实验验证,自抗扰控制器比PI控制能够较好的抑制直流电机的换相转矩脉动,从而能够提高电机在运动中的稳定性。     

基于遗传算法的ADRC参数整定及其应用

自抗扰控制器(ADRC)通过对模型不确定因素和外扰进行补偿，使得控制系统对外扰和不确定因素均有很好的适应能力。它能够有效控制多种工业上较为难控的对象．并表现出极强的鲁棒性和抗干扰性。遗传算法在参数寻优方面，有着其他算法无法比拟的全局寻优能力．本文给出了基于遗传算法的自抗扰控制器的参数整定．并将其应用在几类不同的对象当中，仿真实例表明了通过遗传算法整定的ADRC的良好控制效果。     

基于自抗扰控制算法的两轮自平衡车分析

为解决两轮自平衡车因系统的不确定和驾驶者的不同而导致它的系统参数变化的问题,将自抗扰控制(ADRC)技术应用到两轮自平衡车的自适应控制中。该系统是以加速度计、陀螺仪为姿态传感器,与连有同轴的永磁有刷直流电机为执行机构的两轮自平衡车,考虑车轮与地面的摩擦力因素,通过物理学分析,运用牛顿力学方程建立了系统对应的非线性数学模型,得到了其状态空间方程,将系统解耦成平衡与转向两个独立的子系统,应用自抗扰控制技术估算出系统的总扰动,对系统进行了控制补偿,提出了基于自抗扰控制算法来实现两轮自平衡车的控制的方法。在Matlab中的Simulink模型/建模平台上进行了仿真评价,并通过搭建实验平台进行了不同路况的试验验证。试验结果表明:自抗扰控制技术能够满足两轮自平衡车控制的目标,可以用来控制两轮自平衡车系统。     

Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics

In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance.     

Active disturbance rejection control: Methodology and theoretical analysis

The methodology of ADRC and the progress of its theoretical analysis are reviewed in the paper. Several breakthroughs for control of nonlinear uncertain systems, made possible by ADRC, are discussed. The key in employing ADRC, which is to accurately determine the “total disturbance” that affects the output of the system, is illuminated. The latest results in theoretical analysis of the ADRC-based control systems are introduced.     

Spatial curvilinear path following control of underactuated AUV with multiple uncertainties

This paper investigates the problem of spatial curvilinear path following control of underactuated autonomous underwater vehicles (AUVs) with multiple uncertainties. Firstly, in order to design the appropriate controller, path following error dynamics model is constructed in a moving Serret–Frenet frame, and the five degrees of freedom (DOFs) dynamic model with multiple uncertainties is established. Secondly, the proposed control law is separated into kinematic controller and dynamic controller via back-stepping technique. In the case of kinematic controller, to overcome the drawback of dependence on the accurate vehicle model that are present in a number of path following control strategies described in the literature, the unknown side-slip angular velocity and attack angular velocity are treated as uncertainties. Whereas in the case of dynamic controller, the model parameters perturbations, unknown external environmental disturbances and the nonlinear hydrodynamic damping terms are treated as lumped uncertainties. Both kinematic and dynamic uncertainties are estimated and compensated by designed reduced-order linear extended state observes (LESOs). Thirdly, feedback linearization (FL) based control law is implemented for the control model using the estimates generated by reduced-order LESOs. For handling the problem of computational complexity inherent in the conventional back-stepping method, nonlinear tracking differentiators (NTDs) are applied to construct derivatives of the virtual control commands. Finally, the closed loop stability for the overall system is established. Simulation and comparative analysis demonstrate that the proposed controller exhibits enhanced performance in the presence of internal parameter variations, external unknown disturbances, unmodeled nonlinear damping terms, and measurement noises.     

Performance analysis of active disturbance rejection tracking control for a class of uncertain LTI systems

The paper considers the tracking problem for a class of uncertain linear time invariant (LTI) systems with both uncertain parameters and external disturbances. The active disturbance rejection tracking controller is designed and the resulting closed-loop system׳s characteristics are comprehensively studied. In the time-domain, it is proven that the output of closed-loop system can approach its ideal trajectory in the transient process against different kinds of uncertainties by tuning the bandwidth of extended state observer (ESO). In the frequency-domain, different kinds of parameters׳ influences on the phase margin and the crossover frequency of the resulting control system are illuminated. Finally, the effectiveness and robustness of the controller are verified through the actuator position control system with uncertain parameters and load disturbances in the simulations.     

Stabilizing control for a class of delay unstable processes

The stabilization of unstable first-order plus time-delay processes with a zero by means of simple controllers is investigated in detail. Explicit stabilizability conditions are established. And the computational methods for determining stabilizing controller parameters are also presented with illustrative examples.     

改进自抗扰控制谐波式电动舵机伺服系统

针对电动舵机系统的非线性、快时变等特点,提出了改进的自抗扰控制器以改善系统的位置跟踪性能。首先,给出电动舵机的系统模型及控制策略,分析了系统中非线性因素的影响;设计了改进自抗扰控制器,并利用现代控制理论给出了控制器参数的选择方法。然后,在舵机系统中进行仿真分析,验证了该控制器的可行性。最后,基于谐波式电动舵机对改进的自抗扰控制器与常规自抗扰控制器及PI控制器进行对比实验。实验结果表明:跟踪10sin(5πt)正弦信号时,改进自抗扰控制器能够消除位置平顶和速度死区,相位滞后为0.087 22rad;跟踪±1°~±15°角位置时,上升时间为9~18ms,超调量为0~7.25%,稳态均方差为0.007 60~0.010 83,性能明显优于常规自抗扰控制器和PI控制器。得到的数据显示该控制器减少了设计参数,位置跟踪超调量小,响应时间快,稳态均方差小,改善了舵机系统的动态和稳态性能。     

Reduced-order model based active disturbance rejection control of hydraulic servo system with singular value perturbation theory

Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with the high stiffness control and mismatched uncertainties input problems, which hinder direct applications of many advanced control approaches in the hydraulic servo fields. In this paper, by introducing the singular value perturbation theory, the original double-dynamics coupling model of the hydraulic servomechanism was reduced to a integral chain system. So that, the popular ADRC (active disturbance rejection control) technology could be directly applied to the reduced system. In addition, the high stiffness control and mismatched uncertainties input problems are avoided. The validity of the simplified model is analyzed and proven theoretically. The standard linear ADRC algorithm is then developed based on the obtained reduced-order model. Extensive comparative co-simulations and experiments are carried out to illustrate the effectiveness of the proposed method.     

Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system

Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems.     

A GA-based parameters tuning method for an ADRC controller of ISP for aerial remote sensing applications

This paper presents a parameters tuning method based on the genetic algorithm (GA) for an active disturbance rejection control (ADRC) of a three-axis inertially stabilized platform (ISP) with imaging sensors. To improve the stabilization accuracy and robustness of an aerial ISP under multi-source disturbances environment, an ADRC control scheme is first proposed. Then, to accurately identify and tune the parameters in the ADRC controller, a GA-based parameters tuning method is proposed. In this way, the performance of the ADRC is superior to the empirical method. To validate the proposed method, the simulations and experiments are carried out. The results show that the proposed ADRC with GA-based parameters tuning method has significant disturbance rejection ability which can improve the stabilization accuracy obviously. Compared with the ADRC with empirically tuning method, the stabilization error (RMS) under movable base is decreased up to 50.09%.