高动态离心机系统的自抗扰控制设计

针对传统PID在控制高速精密离心机系统时难以满足其高动态过程的要求,对系统目标过渡过程进行安排并设计了自抗扰控制器.所提出的自抗扰控制器包括3个部分:跟踪微分器、扩张状态观测器和误差反馈控制器.由于离心机在启动和制动阶段,系统状态会经历一个快速变化的过程,所以在离心机系统动态变化阶段采用跟踪微分器对目标函数进行过渡过程安排,防止系统出现过大超调;并且设计了扩张状态观测器对系统未知干扰进行估计和补偿;补偿后采用误差反馈控制器实现离心机系统高动态过程的跟踪控制.最后通过对自抗扰控制进行参数整定,使得系统满足所提出的各项性能指标要求.仿真结果验证了相比于传统PID控制,所提出的自抗扰控制器在超调量,调节时间以及稳态控制精度等性能指标上具有优越性.     

快速路交通密度的自抗扰控制器设计及不同扰动情况下的性能评价

本文针对快速路主道交通密度的控制问题,提出了一种新的自抗扰匝道调节方法.该方法包括跟踪微分器(TD)、扩展状态观测器(ESO)和非线性输出误差反馈控制律(NLOEF)3个部分.通过微分跟踪环节安排的过渡过程,可有效降低系统的超调;而系统外部不确定性可通过ESO估计,并将估计信息用于NLOEF更新控制信号.本文分别基于宏观MATLAB和微观PARAMICS平台进行了仿真研究,验证了所提出方法抑制不同类型外部扰动的有效性.     

多电机驱动系统的保性能鲁棒Funnel控制

本文针对含参数不确定性的多电机驱动系统,提出一种基于最优保性能鲁棒的Funnel控制方法实现系统的规定跟踪性能.该控制方法通过构造Funnel函数对误差系统进行变换,并设计自适应反步控制器保证变换后系统的稳定性即可使跟踪误差的瞬态和稳态响应均被限制在给定的Funnel边界内.然而由于系统中存在的参数不确定性会影响系统的规定控制性能,本文在Funnel控制基础上又设计了最优保性能鲁棒控制器.它是通过将参数不确定性系统的保性能鲁棒控制问题转化为标称系统的最优控制问题,并求解新的黎卡提方程而得到的.因此所设计的控制器不但消除了参数不确定性对系统的影响并且能够使系统的性能指标达到一确定的上界.最后,对四电机驱动系统进行了仿真和实验验证,说明所提出控制方法的有效性.     

无人直升机航向自抗扰控制

针对无人直升机系统航向通道扰动大等问题,本文设计了一种自抗扰控制算法来实现其高性能控制.首先分析了航向通道的动态模型,并通过数学变换,将其转化为一类二阶系统;在此基础上,本文设计了适用于无人机航向通道的自抗扰控制策略,它由跟踪微分器、扩展状态观测器、控制器3个环节构成.本文对所设计的自抗扰控制策略进行了仿真和实验测试,并与常见的串级控制方法进行了对比分析.仿真与实验结果表明:这种自抗扰控制策略具有对扰动抑制能力强、控制精度高等优点,其控制性能明显优于常规的串级比例–积分–微分控制方法.     

光伏阵列清洁机器人路径跟踪改进型自抗扰控制

针对光伏阵列清洁机器人清洁作业过程中存在路径跟踪精度低与外界不确定干扰等问题,提出了一种改进型自抗扰控制策略来控制驱动单元模型,实现驱动单元角速度（力矩）的高鲁棒性控制,从而提高了机器人的路径跟踪精度.通过分析机器人的运动状态,得到清洁机器人实际运动位姿与期望运动位姿之间的误差.由于外界环境以及其他不确定因素的干扰,通过建立清洁机器人移动底盘带不确定干扰因素的动力学控制模型,在传统自抗扰控制器的基础上通过改进fal函数,提出了一种运动学与动力学内外嵌套的改进型自抗扰策略.改进型扩张状态观测器来实时观测并补偿不确定干扰因素,从而实现清洁机器人高精度跟踪作业目标路径.通过多种目标路径的跟踪仿真实验,最终都表现出了较好的跟踪结果.证明了本文所设计的基于改进型自抗扰控制的光伏阵列清洁机器人路径跟踪控制算法的优越性与有效性,提高了光伏阵列清洁机器人的清洁作业路径跟踪精度.     

电液伺服系统的多滑模鲁棒自适应控制

针对一类参数与外负载非匹配不确定的非线性高阶系统,提出了一种基于逐步递推方法的多滑模鲁棒自适应控制策略.应用逐步递推的多滑模控制方法简化了高阶系统的控制问题,同时在自适应控制中加入鲁棒控制的方法,以消除不确定性对控制性能的影响.首先利用逐步递推方法与状态反馈精确线性化理论,得出确定系统的多滑模控制器设计方法;然后基于Lyapunov稳定性分析方法,给出不确定系统的参数自适应律,及鲁棒自适应控制器的设计方法.本文把该控制策略应用到电液伺服系统的位置跟踪控制中,仿真结果显示,该控制方法具有较强的鲁棒性及良好的跟踪效果.     

Predefined-time control for Euler–Lagrange systems with model uncertainties and actuator faults

A novel adaptive predefined-time tracking control algorithm is proposed for the Euler–Lagrange systems (ELSs) with model uncertainties and actuator faults. Compared with traditional finite-time and fixed-time studies, the system output tracking error under the proposed predefined-time controller converges to a small neighborhood of zero in finite time, whose upper bound is exactly a design parameter in the control algorithm. For the uncertain model, radial-based function neural network (RBFNN) is utilized to approximate the continuous uncertain dynamics. To deal with the actuator faults, an adaptive control law is involved in the fault-tolerant controller. In order to achieve the predefined-time bounded, a novel predefined-time sliding mode surface is designed. It is proved that the tracking error vector trajectory of closed-loop system is semi-globally uniformly ultimately predefined-time bounded, and the upper bounds of both the system settling time and the corresponding output tracking error can be adjusted with a simple parameter. Simulation examples finally demonstrate the effectiveness of the proposed control algorithm.     

Anti‐windup design of active disturbance rejection control for sampled systems with input delay

A novel anti‐windup design of active disturbance rejection control (ADRC) is proposed for industrial sampled systems with input delay and saturation. By using a generalized predictor to estimate the delay‐free system output, a modified extended state observer is designed to simultaneously estimate the system state and disturbance, which could become an anti‐windup compensator when the input saturation occurs. Accordingly, a feedback controller is analytically designed for disturbance rejection. By proposing the desired closed‐loop transfer function for the set‐point tracking, a prefilter is designed to tune the tracking performance while guaranteeing no steady‐state output tracking error. A sufficient condition for the closed‐loop system stability is established with proof for practical application subject to the input delay variation. Illustrative examples from the literature are used to demonstrate the effectiveness and merit of the proposed control design.     

An optimal adaptive H-infinity tracking control design via wavelet network

In this paper, an optimal adaptive H-infinity tracking control design method via wavelet network for a class of uncertain nonlinear systems with external disturbances is proposed to achieve H-infinity tracking performance. First, an alternate tracking error and a performance index with respect to the tracking error and the control effort are introduced in order to obtain better performance, especially, in reducing the cost of the control effort in the case of small attenuation levels. Next, H-infinity tracking performance, which attenuates the influence of both wavelet network approximation error and external disturbances on the modified tracking error, is formulated. Our results indicate that a small attenuation level does not lead to a large control signal. The proposed method insures an optimal trade-off between the amplitude of control signals and the performance of tracking errors. An example is given to illustrate the design efficiency.     

基于FOPID+ADRC的永磁同步电机低速控制

永磁同步电机(permanent magnet synchronous motor,PMSM)是一个非线性、多变量、强耦合系统,具有不确定的外部干扰。为了提高其低速运行时的控制精度,采用一种改进自抗扰控制(active disturbance rejection control,ADRC)对其进行控制。首先通过插值法构建一个新的非线性函数来代替ADRC中原有的最优控制函数,使其在原点处更平滑和连续。并将此函数应用于扩张观测器(extended state observer,ESO),最后将非线性误差反馈率(nonlinear state error feedback,NLSEF)用分阶数比例积分微分(fractional-order proportion integration differentiation,FOPID)代替以提高其动态性能。经SIMULINK仿真结果表明,该控制算法在PMSM低速控制中比传统ADRC具有更快的响应速度和更好的抗干扰能力。     

Prescribed Performance Control of One-DOF Link Manipulator With Uncertainties and Input Saturation Constraint

In this paper, we mainly address the position control problem for one-degree of freedom (DOF) link manipulator despite uncertainties and the input saturation via the backstepping technique, active disturbance rejection control (ADRC) as well as predefined tracking performance functions. The extended state observer (ESO) is employed to compensate uncertain dynamics and disturbances, and it does not rely on the accurate model of systems. The tracking differentiator (TD) is utilized to substitute the derivative of the virtual control signals, and the explosion of complexity caused by repeated differentiations of nonlinear functions is removed. The auxiliary system is used to deal with the control input limitation, and the tracking accuracy and speed are improved by predefined tracking performance functions. With the help of the input-to-state stability (ISS) and Lyapunov stability theories, it is proven that the tracking error can be gradually converged into arbitrarily small neighborhood of the origin, and the tracking error is adjusted by suitable choice of control parameters. The simulation results are presented for the verification of the theoretical claims.      

Active Disturbance Rejection Control for Uncertain Nonlinear Systems With Sporadic Measurements

This paper deals with the problem of active disturbance rejection control (ADRC) design for a class of uncertain nonlinear systems with sporadic measurements. A novel extended state observer (ESO) is designed in a cascade form consisting of a continuous time estimator, a continuous observation error predictor, and a reset compensator. The proposed ESO estimates not only the system state but also the total uncertainty, which may include the effects of the external perturbation, the parametric uncertainty, and the unknown nonlinear dynamics. Such a reset compensator, whose state is reset to zero whenever a new measurement arrives, is used to calibrate the predictor. Due to the cascade structure, the resulting error dynamics system is presented in a non-hybrid form, and accordingly, analyzed in a general sampled-data system framework. Based on the output of the ESO, a continuous ADRC law is then developed. The convergence of the resulting closed-loop system is proved under given conditions. Two numerical simulations demonstrate the effectiveness of the proposed control method.      

Dual closed‐loop tracking control for wheeled mobile robots via active disturbance rejection control and model predictive control

A dual closed‐loop tracking control is proposed for a wheeled mobile robot based on active disturbance rejection control (ADRC) and model predictive control (MPC). In the inner loop system, the ADRC scheme with an extended state observer (ESO) is proposed to estimate and compensate external disturbances. In the outer loop system, the MPC strategy is developed to generate a desired velocity for the inner loop dynamic system subject to a diamond‐shaped input constraint. Both effectiveness and stability analysis are given for the ESO and the dual closed‐loop system, respectively. Simulation results demonstrate the performances of the proposed control scheme.     

基于核相关滤波的无人机偏航角跟踪控制系统设计

针对非线性自抗扰控制技术设计的系统、线性自抗扰技术设计的系统受到噪声影响,导致信号传输受到阻碍,出现偏航角跟踪控制结果精准度低的问题,提出了基于核相关滤波的无人机偏航角跟踪控制系统设计;在系统总体架构支持下,采用STM32F407型号主控芯片,保证无人机控制系统稳定性;在方向盘下安装有转向角传感器,为ESP电子控制单元提供方向盘;使用频率为2.4 GHz遥控器接收机生成具有不同脉冲宽度PWM信号,通过控制旋翼偏航控制器,推动旋翼在不同角度指令下旋转;利用核相关滤波器过滤目标图像,通过滤波器的输运来估计目标运动位置,并确定地面参考坐标系与无人机机体坐标系,构成无人机在空间中六个自由度,由此设计偏航角跟踪控制软件流程,跟踪控制无人机偏航角;由实验结果可知,该系统滚转角与实际值轨迹一致,误差为0;俯仰角与实际值轨迹有偏差,误差为0.05°,为无人机向不同方向精准飞行提供系统支持.     

基于控制性能的MIMO非线性系统动态面控制

针对一类不确定非线性MIMO(multiple-input multiple-output)系统,在动态面控制方法的基础上,提出了自适应跟踪控制方案.通过引入性能函数和输出误差转换,保证输出信号具有指定的跟踪速度、跟踪误差、最大超调量.为了避免控制奇异问题,采用神经网络直接逼近期望控制信号.该方案无需估计神经网络的权值,仅对1个参数进行自适应律设计.理论证明了闭环系统所有信号有界,仿真结果验证了所提方案的有效性.     

Robust Control System Design for an Uncertain Nonlinear System Using Minimax LQG Design Method

A systematic approach to design a nonlinear controller using minimax linear quadratic Gaussian regulator (LQG) control is proposed for a class of multi‐input multi‐output nonlinear uncertain systems. In this approach, a robust feedback linearization method and a notion of uncertain diffeomorphism are used to obtain an uncertain linearized model for the corresponding uncertain nonlinear system. A robust minimax LQG controller is then proposed for reference command tracking and stabilization of the nonlinear system in the presence of uncertain parameters. The uncertainties are assumed to satisfy a certain integral quadratic constraint condition. In this method, conventional feedback linearization is used to cancel nominal nonlinear terms and the uncertain nonlinear terms are linearized in a robust way. To demonstrate the effectiveness of the proposed approach, a minimax LQG‐based robust controller is designed for a nonlinear uncertain model of an air‐breathing hypersonic flight vehicle (AHFV) with flexibility and input coupling. Here, the problem of constructing a guaranteed cost controller which minimizes a guaranteed cost bound has been considered and the tracking of velocity and altitude is achieved under inertial and aerodynamic uncertainties.     

非仿射系统的自适应观测器自抗扰控制

研究了一类单输入单输出(SISO)非仿射非线性系统的控制问题,通过微分同胚变换以及自抗扰思想将该类形式转化成含有未知非线性且控制增益未知的仿射形式.引入扩展状态自适应观测器以及Nussbaum-type增益技术,利用积分反演和调节函数技术,设计了自抗扰控制器.从理论上证明了所设计的控制器能够保证闭环系统所有信号全局一致有界,并且证明了跟踪误差渐近收敛到零点的残集内.仿真例子验证了算法的有效性.     

Superheated steam temperature control based on modified active disturbance rejection control

Control of superheated steam temperature (SST) is becoming more and more challenging because of unknown disturbances caused by the frequent and extensive load changes and strict control requirements for the efficiency and safety. This is becoming even severe while the intermittent renewables penetration is growing. To this end, the working principle of SST is depicted and the models of SST are identified from the open-loop step response data. Considering the sluggish responses to the disturbances caused by high order dynamics, a modified active disturbance rejection control (ADRC) is proposed to enhance the control performance. Stability analysis of modified ADRC is derived theoretically to perfect the theory of modified ADRC. Then a practical tuning procedure is summarized for modified ADRC that can be readily understood by field engineers even though it involves trial and error tests. A simulation example shows that modified ADRC can improve the performance of tracking and disturbance rejection simultaneously while maintain a good robustness. A modified ADRC based cascade control strategy is proposed for the SST control system and the control performance is initially confirmed by a simulation based on the identified models. A field application in a 300 MW circulating fluidized bed (CFB) power plant demonstrates the advantages of the proposed strategy, which shows the temperature deviation can be significantly reduced in both the small-scale load varying condition and the large-scale load varying condition. The successful application of the proposed SST control system indicates a promising future of modified ADRC in power industry with the increasing demand on integrating more renewables into the power grid.     

一种基于指数趋近律的非线性系统变结构轨迹跟踪控制新方法

针对多输入多输出二阶不确定非线性机械系统中轨迹跟踪控制的问题,提出一种新的基于指数趋近律的滑模变结构控制方法,用于提高系统的平稳性和快速性。在滑模变结构控制器设计过程中采用一种新的指数趋近律以改进闭环系统的暂态和稳态响应性能,使系统跟踪误差收敛速度加快,特别是减少轨迹跟踪误差到达滑模面的时间,同时提高了系统轨迹跟踪过程的平稳性。通过采用边界层方法消除滑模控制输入抖振问题,避免控制过程中执行器的频繁切换,进一步提高所提出滑模控制器在实际系统中的实用性。基于李雅普诺夫稳定性理论证明了闭环系统的稳定性和跟踪误差的收敛性。数值仿真验证了所提出的控制方法的有效性。     

Chattering free adaptive fuzzy terminal sliding mode control for second order nonlinear system

A novel fuzzy terminal sliding mode control （FTSMC） scheme is proposed for position tracking of a class of second-order nonlinear uncertain system. In the proposed scheme, we integrate input-output linearization technique to cancel the nonlinearities. By using a function-augmented sliding hyperplane, it is guaranteed that the output tracking error converges to zero in finite time which can be set arbitrarily. The proposed scheme eliminates reaching phase problem, so that the closed-loop system always shows invariance property to parameter uncertainties. Fuzzy logic systems are used to approximate the unknown system functions and switch item. Robust adaptive law is proposed to reduce approximation errors between true nonlinear functions and fuzzy systems, thus chattering phenomenon can be eliminated. Stability of the proposed control scheme is proved and the scheme is applied to an inverted pendulum system. Simulation studies are provided to confirm performance and effectiveness of the proposed control approach.