An extended state observer with adjustable bandwidth for measurement noise

In this paper,a bandwidth-adjustable extended state observer(ABESO)is proposed for the systems with measurement noise.It is known that increasing the bandwidth of the observer improves the tracking speed but tolerates noise,which conflicts with observation accuracy.Therefore,we introduce a bandwidth scaling factor such that ABESO is formulated to a 2-degree-of-freedom system.The observer gain is determined and the bandwidth scaling factor adjusts the bandwidth according to the tracking error.When the tracking error decreases,the bandwidth decreases to suppress the noise,otherwise the bandwidth does not change.It is proven that the error dynamics are bounded and converge in finite time.The relationship between the upper bound of the estimation error and the scaling factor is given.When the scaling factor is less than 1,the ABESO has higher estimation accuracy than the linear extended state observer(LESO).Simulations of an uncertain nonlinear system with compound disturbances show that the proposed ABESO can successfully estimate the total disturbance in noisy environments.The mean error of total disturbance of ABESO is 15.28% lower than that of LESO.

Differential geometric guidance command with finite time convergence using extended state observer

For improving the performance of differential geometric guidance command(DGGC), a new formation of this guidance law is proposed, which can guarantee the finite time convergence(FTC) of the line of sight(LOS) rate to zero or its neighborhood against maneuvering targets in three-dimensional(3D) space. The extended state observer(ESO) is employed to estimate the target acceleration, which makes the new DGGC more applicable to practical interception scenarios. Finally, the effectiveness of this newly proposed guidance command is demonstrated by the numerical simulation results.

Extended state observer based smooth switching control for tilt-rotor aircraft

A tilt-rotor aircraft has three flight modes: helicopter mode, airplane mode and conversion mode. Unlike the traditional aircraft, the tilt-rotor aircraft, which combines the characteristics of helicopters and fixed-wing aircraft, is a complex multi-body system with the violent variation of the aerodynamic parameters. For these characteristics, a new smooth switching control scheme is provided for the tilt-rotor aircraft. First, the reference commands for airspeed and nacelle angles are calculated by analyzing the conversion corridor and the conversion path. Subsequently, based on the finite-time switching theorem, an average dwell time condition is designed to guarantee the stability in the switching process. Besides, considering the state vibrations and bumps may appear in switching points, the fuzzy weighted logic is employed to improve the system transient performance. For disturbance rejection, three extended state observers are designed separately to estimate the disturbances in the switched systems. Compared with the traditional auto disturbance rejection control and proportion integration differentiation control, this method overcomes the conservatism of wasting the whole model information. The control performances of robustness and smoothness are verified with simulation, which shows that the new smooth switching control scheme is more targeted and superior than the traditional design method.

Civil aircraft fault tolerant attitude tracking based on extended state observers and nonlinear dynamic inversion

For the problem of sensor faults and actuator faults in aircraft attitude control,this paper proposes a fault tolerant control(FTC)scheme based on extended state observer(ESO)and nonlinear dynamic inversion(NDI).First,two ESOs are designed to estimate sensor faults and actuator faults respectively.Second,the angular rate signal is reconstructed according to the estimation of sensor faults.Third,in angular rate loop,NDI is designed based on reconstruction of angular rate signals and estimation of actuator faults.The FTC scheme proposed in this paper is testified through numerical simulations.The results show that it is feasible and has good fault tolerant ability.

基于ESO的仿蝙蝠扑翼飞行器姿态控制仿真

针对仿蝙蝠扑翼飞行器的纵向气动特性不稳定、易受扰动的问题,设计了一种基于扩张状态观测器(ESO)的姿态控制方法,实现了扑翼飞行器姿态的稳定与抗干扰控制。首先建立仿蝙蝠扑翼飞行器的动力学模型;进而在该模型基础上分析了扑翼飞行器的纵向稳定性;然后将系统的不确定部分与各种未知的外界扰动作为系统的总扰动,引入ESO模块对总扰动进行实时观测与跟踪;最后在原有的PID控制器中加入扰动补偿环节。数值仿真结果表明,基于ESO的控制算法对于仿蝙蝠扑翼飞行器的控制效果显著优于基于PID的控制方法,阶跃响应的调节时间加快41.27%,对系统输入的白噪声干扰波动峰值从6.02%降低到2.82%,正弦扰动的波动峰值从11.56%降低到3.22%。

An Improved Deadbeat Predictive Current Control Method for SPMSM Drives with a Novel Adaptive Disturbance Observer

To improve the dynamic performance of conventional deadbeat predictive current control(DPCC)under parameter mismatch,especially eliminate the current overshoot and oscillation during torque mutation,it is necessary to enhance the robustness of DPCC against various working conditions.However,the disturbance from parameter mismatch can deteriorate the dynamic performance.To deal with the above problem,firstly,traditional DPCC and the parameter sensitivity of DPCC are introduced and analyzed.Secondly,an extended state observer(ESO)combined with DPCC method is proposed,which can observe and suppress the disturbance due to various parameter mismatch.Thirdly,to improve the accuracy and stability of ESO,an adaptive extended state observer(AESO)using fuzzy controller based on ESO,is presented,and combined with DPCC method.The improved DPCC-AESO can switch the value of gain coefficients with fuzzy control,accelerating the current response speed and avoid the overshoot and oscillation,which improves the robustness and stability performance of SPMSM.Finally,the three methods,as well as conventional DPCC method,DPCC-ESO method,DPCC-AESO method,are comparatively analyzed in this paper.The effectiveness of the proposed two methods are verified by simulation and experimental results.

基于FxTSMC-ESO的永磁同步电机调速系统滑模控制

针对永磁同步电机速度环中存在的外部负载扰动问题,为了提高速度环控制系统的动态性和鲁棒性,提出一种基于新型固定时间滑模控制器与扩张状态观测器的控制方法。所提出的滑模控制器简化了收敛时间公式,解决了快速响应与抑制抖振的矛盾。为了进一步提升调速系统的鲁棒性,采用固定时间收敛的扩张状态观测器对控制器的扰动进行前馈补偿,该观测器不仅可以减小趋近律的开关函数增益,还能实现扰动的精准观测。仿真验证了所提滑模控制方法的有效性。

基于ESO的分拣并联机器人无标定视觉伺服自适应滑模控制

针对无标定分拣并联机器人需获取精确图像雅可比矩阵的问题,同时为克服图像检测误差、建模误差及外部干扰对无标定视觉伺服系统的影响,提出一种基于扩张状态观测器(extended state observer,ESO)的分拣并联机器人无标定视觉伺服自适应滑模控制方法。通过将表征机器人图像空间与任务空间映射关系的图像雅可比矩阵与系统不确定项集总到同一通道的状态方程,引入ESO对分拣并联机器人视觉伺服系统的集总不确定性进行在线估计,设计一种基于扩张状态观测器的自适应积分滑模控制器,并通过设计自适应律动态调整滑模控制切换增益,以提高视觉伺服系统精度,同时达到抑制滑模控制抖振的效果。采用Lyapunov稳定性理论证明该控制方法的稳定性,最后通过仿真实验验证了所提出视觉伺服自适应滑模控制方法的可行性和有效性。

基于连续可导ESO的虚拟同步机控制策略

在高比例新能源接入的电网中,虚拟同步机技术被广泛应用,但当面对系统扰动时其稳定性较差,可能会存在电压过限、频率波动等问题。因此,为了提高电能质量,将扩张状态观测器引入虚拟同步机控制技术中,对扰动进行观测、估计与补偿,提高系统稳定性,从而在新能源电源波动及大功率负荷投切时得到更稳定的母线电压及系统频率。此外,进一步对扩张状态观测器中的分段函数fal进行矫正,提出一种连续可导的扩张状态观测器控制算法,免去运算过程中的判断环节,突出了“小误差大增益”的特点,并对算法进行稳定性分析和确定参数选择范围。仿真与实验结果验证了所提策略的有效性与可行性。

Solid Rocket Booster Thrust Asynchrony Identification Method for Solid Rocket Bundled Rockets With ESO

The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.

Robust Disturbance Rejection Based Control with Extended-state Resonant Observer for Sway Reduction in Uncertain Tower-cranes

In this paper, the problem of load transportation and robust mitigation of payload oscillations in uncertain tower-cranes is addressed. This problem is tackled through a control scheme based on the philosophy of active-disturbance-rejection. Here, a general disturbance model built with two dominant components: polynomial and harmonic, is stated. Then, a disturbance observer is formulated through state-vector augmentation of the tower-crane model. Thus, better performance of estimations for system states and disturbances is achieved. The control law is then formulated to actively reject the disturbances but also to accommodate the closed-loop system dynamics even under system uncertainty. The proposed control schema is validated via experimentation using a small-scale tower-crane,and compared with other relevant active disturbance rejection control(ADRC)-based techniques. The experimental results show that the proposed control scheme is robust under parametric uncertainty of the system, and provides improved attenuation of payload oscillations even under system uncertainty.

基于ESO的磁悬浮直线同步电机变增益自适应迭代学习控制

对于可控励磁磁悬浮直线同步电机(CEMLLSM),常规迭代学习控制(ILC)精度低、抖振大,且抗外部扰动能力差。为提高跟踪精度,设计了一种基于扩张状态观测器(ESO)的变增益自适应ILC算法。首先,研究CEMLLSM的工作原理及数学模型。其次,设计基于ESO的变增益自适应迭代学习控制器,为控制器中固定增益部分引入指数可变增益,增加自适应迭代项对控制律中的未知参数进行迭代学习,从而减小系统抖振与误差并加快系统收敛速度。通过引入ESO观测系统的外部干扰,对控制量进行补偿,进而提高系统的抗扰动能力。最后,用MATLAB对控制系统进行仿真分析,仿真结果表明该算法能够有效减小跟踪误差,并对扰动有良好的抑制作用。

基于非线性-线性ESO切换策略的船舶柴油机转速控制

为更好地适应船舶柴油机转速和负载分布范围广泛的特点,针对船舶柴油机转速控制,在分析扩张状态观测器(ESO)特性的基础上,结合非线性ESO(NLESO)和线性ESO(LESO)的优点,通过切换策略构建基于NLESO和LESO的自抗扰控制器(ADRC)。该控制器考虑了实际柴油机转速控制中基于曲轴转角计算和控制的特点,其计算和控制由曲轴转角信号定角度触发,并对曲轴转角触发的ESO进行了稳定性分析。最终的发动机试验表明:相对于PID控制器、线性自抗扰控制器和非线性自抗扰控制器,基于切换ESO的自抗扰控制器对柴油机转速和负载变化具有更好的适应性和鲁棒性。

基于改进ESO的反馈线性化四旋翼无人机姿态控制

针对四旋翼飞行器非线性、强耦合的特性以及存在建模误差和未知扰动下姿态控制问题,提出了一种改进自抗扰控制方案。利用反馈线性化方法将无人机姿态动力学模型转化为线性模型,减少了小扰动假设带来的系统误差;改进了扩张状态观测器(ESO)的结构,使其能同时利用角度和角速度的测量信息,提高了其对时变扰动的估计精度;基于改进ESO完成了自抗扰控制器的设计并证明了该控制系统的稳定性。仿真实验结果表明,基于改进ESO的自抗扰控制器具有更强的抗干扰性和鲁棒性。

基于sigmoid滤波器的永磁轮毂电机自抗扰控制

相比燃油拖拉机,电动拖拉机具有节能高效、绿色清洁的优点。分布式驱动电动拖拉机结构简单、控制维度多,能进一步提高电动拖拉机的工作效率和作业精度。但是电机检测转速噪声导致轮毂电机速度波动严重,复杂路面及多种作业工况下进一步加剧了上述问题,严重降低了拖拉机的作业质量。针对上述问题,该研究提出一种基于sigmoid滤波器的线性自抗扰控制(linear active disturbance rejection control,LADRC)以提高轮毂电机的转速稳定性和抗扰动能力。该控制策略在传统LADRC的基础上引入sigmoid滤波器至扩张状态观测器(extended state observer,ESO),根据输入噪声信号误差变化改变滤波器带宽,以抑制观测误差中的中高频干扰信号,同时避免滤波器积分环节对轮毂电机速度跟踪快速性的影响,具有较快的收敛性。搭建试验平台对所提出控制策略进行试验验证,结果表明:与传统LADRC策略相比,本文所提控制策略在变速和变载工况下的转速脉动分别减小了32%和41.67%,iq电流脉动分别减小了6.25%和4.17%,可在快速、准确跟踪给定转速的同时,大幅提高轮毂电机驱动系统的噪声抑制性能,为复杂环境下电动拖拉机高精度作业提供技术参考。

Analysis and design for the second order nonlinear continuous extended states observer

The extended state observer (ESO) is a novel observer for a class of uncertain systems. Since ESO adopts the continuous non-smooth structure, the classical observer design theory is hard to use for ESO analysis. In this note, the self-stable region (SSR) approach, which is a nonlinear synthesis method for nonlinear uncertain systems, will be used for ESO design and its stability analysis. The advantages of the non-smooth structure in ESO for improving the convergence properties and the estimation precision will be shown.

基于扩张状态观测器和抗饱和输入的伺服电机等效反步滑模控制

为了提高伺服电机系统的动态响应速度、抗干扰能力,解决输入饱和的问题,课题组基于扩张状态观测器(extended state observer,ESO)和抗饱和输入(anti-saturation input,ASI)辅助系统设计了伺服电机的运动控制方案。首先,建立了伺服电机的数学模型,将系统阻尼和系统不确定性归为扰动,将扰动设为系统的扩张状态;然后在等效反步滑模控制(backstepping sliding mode control,BSMC)的基础上,引入了ASI辅助系统和ESO,解决输入饱和问题,并抑制内、外干扰;采用双曲正切饱和函数替换符号函数以减小滑模控制的抖振;通过李雅普诺夫稳定性方法检验所提出控制器的稳定性。最后,将基于ESO和ASI的等效反步滑模控制与比例积分微分(proportional integral differential,PID)控制、滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:相较于传统PID和SMC控制器,课题组所设计的控制器可以实现伺服电机的无超调快速响应,解决了输入饱和问题,并具有较好的抗干扰能力和减小输入冲击的作用。

通信速率约束下一体化角度协同制导控制方法

针对多飞行器协同拦截过程中的角度协同问题,设计了一种基于量化编码器的分布式一体化协同制导控制律。首先建立多飞行器协同制导与控制数学模型,并基于扩张状态观测器理论,对单个飞行器各状态进行观测。在此基础上考虑各飞行器间单次传输数据的字长、两次传输数据间隔的通信速率约束,采用量化器-编码器-解码器实现限制通信速率情况下的协同一体化制导控制设计。之后,通过严格的理论分析证明了满足强连通图有向通信网络下,多飞行器系统能够达成一致性且收敛到期望的相对视线角,并给出了满足收敛条件的参数选择范围。最后,通过数学仿真校验,验证了所提出的方法在较低的通信速率下能够完成协同。

基于ESO与终端滑模控制的直流配电网母线电压控制

针对直流配电网中母线电压控制问题,在双向AC/DC变换器传统双闭环控制器的基础上,设计一种基于扩张状态观测器（extended state observer,ESO）和终端滑模的非线性鲁棒电流前馈控制器,在不需要增加额外电压/电流传感器的情况下实现对系统内扰动的快速跟踪,有利于直流配电网中分布式电源与负荷的扩展和即插即用。传统电流前馈控制需要多个电流传感器采集负载电流信息,利用ESO与终端滑模控制理论将电流前馈控制系统转变为以直流母线电压为输入信号的非线性鲁棒电流前馈控制器,有效避免额外传感器的加入,减少装置费用,并且ESO可对系统各状态以及系统模型的不确定性和外部扰动进行实时跟踪,实现对系统中母线电压波动的快速抑制。软件数值仿真结果表明,该控制器表现出良好的控制效果和鲁棒性,对于直流母线电压波动具有很好的稳定效果。

基于ESO的欠驱动四旋翼飞行器轨迹鲁棒控制

针对欠驱动四旋翼无人飞行器的系统特性,为解决传统四旋翼飞行控制方法中存在的弱点,如系统状态变量间相互有较大耦合、控制效果易受建模误差的影响及抵御外界干扰能力较弱等弱点,设计一种基于扩张状态观测器(extended state observer,ESO)的轨迹跟踪算法,由ESO实现对系统复合干扰的估计,并在控制律中对复合干扰进行实时补偿。由于ESO只需要测量系统输出即可实现对复合干扰的精确估计,因此在实际系统中易于实现,为验证所提算法,进行两种不同情况下的仿真研究,分别为矩形轨迹跟踪和圆形轨迹跟踪,仿真结果验证了所提算法的可行性。