基于扩张状态观测器和反步法的四旋翼飞行器姿态控制

四旋翼飞行器在实际执行任务过程中,往往会受到外界的干扰,同时建立模型时的不确定性也会对控制效果产生影响。为了提高系统的鲁棒性,设计了一种基于扩张状态观测器和反步法的姿态控制器。基于牛顿-欧拉方程建立了四旋翼飞行器的数学模型,通过设计扩张状态观测器,以此观测四旋翼飞行器受到的扰动,将观测到的扰动估计值补偿至反步控制器,以减小扰动的影响,改善控制效果。通过数值仿真验证了算法的有效性。     

基于扩张状态观测器的四旋翼吊挂飞行系统非线性控制

针对一类四旋翼飞行器吊挂飞行系统的负载摆动抑制和轨迹跟踪精确控制的问题, 考虑系统存在未知外界扰动和模型动态不确定的情况, 提出一种基于扩张状态观测器(Extended state observer, ESO)的吊挂负载摆动抑制的非线性轨迹跟踪控制方法. 将四旋翼吊挂飞行系统分解为姿态、位置和负载摆动控制三个动态子系统, 分别设计非线性控制器实现欠驱动约束下的解耦控制; 设计一种扩张状态观测器, 用以估计和补偿四旋翼与吊挂负载耦合飞行的未知外界扰动与模型动态不确定性, 并验证了闭环系统的稳定性, 跟踪误差及吊挂负载摆动所有信号的一致最终有界. 最后, 利用Quanser公司的Qball2飞行器进行三维空间螺旋轨迹的跟踪控制, 仿真结果验证了未知干扰下基于扩张状态观测器的四旋翼吊挂飞行非线性控制的有效性和优越性, 实现了四旋翼吊挂系统轨迹跟踪的精确控制和飞行过程中负载摆动的快速抑制.     

基于观测器的伺服系统反馈线性化控制

基于重载且负载大范围变化的伺服系统提出高精度数学模型,建立扩展卡尔曼观测器对速度和模型中参数进行观测,使用基于模型的反馈线性化方法准确地将模型线性化,并使用线性控制方法设计高精度控制器。该策略的应用不但避免了传感器的测量时带来的误差,同时,在参数准确的条件下能够得到更高的控制精度。仿真实验结果表明:运用所设计的基于扩展卡尔曼观测器的反馈线性化控制策略不仅能够准确地对速度状态和参数进行观测,同时系统在跟踪性能方面也取得了较好的结果。     

基于有限时间输出反馈的线性扩张状态观测器

为快速、准确地观测系统中的未知扰动及状态, 提出一种有限时间线性扩张状态观测器(Finite-time linear extended state observer, FT-LESO), 它具有期望的收敛性能且结构简单、易于设计. 假设系统的状态无法量测, 观测器设计问题转化为扰动下的输出反馈控制问题. 针对该问题, 提出一种扰动下的有限时间线性输出反馈控制方法, 得到控制器参数与闭环系统状态向量2-范数间的解析关系. 在此基础上, 提出有限时间线性扩张状态观测器, 得到观测器参数与观测误差收敛速度及稳态观测误差间的解析关系, 给出一充分条件保证观测误差有限时间有界、且能以不低于指数收敛的速度收敛到给定范围内, 为观测器参数设计提供理论依据. 通过数值仿真验证提出的观测器, 仿真结果与理论分析相符, 提出的观测器是有效的.     

基于广义扩张状态观测器的遥操作系统同步控制

针对机械臂遥操作系统中存在的时变时延问题,提出了基于广义扩张状态观测器的控制方法,实现了遥操作系统稳定并且主从机械臂关节角位置同步的控制目标。首先通过反馈线性化,将遥操作系统的主从机械臂动力学模型转化为一个关于位置跟踪误差和时延的状态空间模型。针对该多输入多输出的干扰不匹配模型,设计了广义扩张状态观测器和相应的控制律,从而消除了时变时延以及其它扰动引起的不确定性对系统的影响,并对系统进行稳定性和抗扰性分析。最后,通过仿真验证了所设计的控制方法的有效性。     

基于状态观测器的H-状态反馈控制

本文提出一种基于状态观测器的H_∞曲状态反馈控制,把输出反馈的H_∞控制问题转换成使用状态观测器的H_∞控制问题.通过直接求解状态空间方程,可以获得使用状态观测器的H_∞控制器及其存在的充要条件,它依赖于两个Rjccati方程的解,而且对控制对象的约束不需要满足所谓的正交条件,状态观测器的阶数与控制对象相同,它的输出是控制对象在最坏扰动作用下的状态估计值。     

基于神经网络的非线性扩张状态观测器

自抗扰控制方法是一种新型的非线性设计方法,在自抗扰控制器中主要存在着确定待定参数的问题;非线性扩张状态观测器是自抗扰控制器的核心,在研究非线性扩张观测器中的参数整定问题时,将神经网络的思想引入参数整定,提出了基于神经网络的非线性扩张状态观测器的设计方法,运用该方法可以对任意阶的非线性扩张状态观测器进行参数设计;大量仿真算例表明,设计出的观测器具有良好的鲁棒性,有一定工程应用参考价值.     

基于状态反馈的功率放大器线性化方法

笛卡尔座标反馈线性化技术是减小RF功率放大器非线性失真的一种有效方式,但在高频输入下信号传输延时使系统类似于一高阶系统,严重影响反馈系统的稳定性,一般只适用于窄带系统。为提高系统性能,提出了一种新的状态反馈的线性化技术,并通过二次优化实现参数的优化配置并进行仿真。仿真结果表明通过新方法设计的Cartesian回路增强了系统的稳定性,提高了反馈线性化技术的线性化带宽,而且设计的系统对延时的变化具有较强的鲁棒性。     

基于LESO的MMC-RPC反馈线性化直接功率控制

模块化多电平铁路功率调节器作为一个耦合的多变量非线性系统, 传统PI控制的直接功率控制难以实现 对系统的精确解耦. 本文提出了一种基于线性扩张状态观测器的反馈线性化直接功率控制方法, 根据Lie导数构建 了模块化多电平铁路功率调节器(MMC-RPC)两输入/两输出功率仿射模型, 设计了精确反馈线性化功率解耦控制 器. 针对不确定因素等扰动对精确反馈线性化控制效果的影响, 设计了线性扩张状态观测器对扰动进行观测和补 偿, 实现了功率的精确跟踪控制. 最后, 通过MATLAB/Simulink平台搭建仿真模型对所提控制方法进行了验证.     

Extended state observer for uncertain lower triangular nonlinear systems

The extended state observer (ESO) is a key part of the active disturbance rejection control approach, a new control strategy in dealing with large uncertainty. In this paper, a nonlinear ESO is designed for a kind of lower triangular nonlinear systems with large uncertainty. The uncertainty may come from unmodeled system dynamics and external disturbance. We first investigate a nonlinear ESO with high constant gain and present a practical convergence. Two types of ESO are constructed with explicit error estimations. Secondly, a time varying gain ESO is proposed for reducing peaking value near the initial time caused by constant high gain approach. The numerical simulations are presented to show visually the peaking value reduction. The mechanism of peaking value reduction by time varying gain approach is analyzed.     

Feedback linearization vs. adaptive sliding mode control for a quadrotor helicopter

This paper presents two types of nonlinear controllers for an autonomous quadrotor helicopter. One type, a feedback linearization controller involves high-order derivative terms and turns out to be quite sensitive to sensor noise as well as modeling uncertainty. The second type involves a new approach to an adaptive sliding mode controller using input augmentation in order to account for the underactuated property of the helicopter, sensor noise, and uncertainty without using control inputs of large magnitude. The sliding mode controller performs very well under noisy conditions, and adaptation can effectively estimate uncertainty such as ground effects. Recommended by Editorial Board member Hyo-Choong Bang under the direction of Editor Hyun Seok Yang. This work was supported by the Korea Research Foundation Grant (MOEHRD) KRF-2005-204-D00002, the Korea Science and Engineering Foundation(KOSEF) grant funded by the Korea government(MOST) R0A-2007-000-10017-0 and Engineering Research Institute at Seoul National University. Daewon Lee received the B.S. degree in Mechanical and Aerospace Engineering from Seoul National University (SNU), Seoul, Korea, in 2005, where he is currently working toward a Ph.D. degree in Mechanical and Aerospace Engineering. He has been a member of the UAV research team at SNU since 2005. His research interests include applications of nonlinear control and vision-based control of UAV. H. Jin Kim received the B.S. degree from Korea Advanced Institute of Technology (KAIST) in 1995, and the M.S. and Ph.D. degrees in Mechanical Engineering from University of California, Berkeley in 1999 and 2001, respectively. From 2002–2004, she was a Postdoctoral Researcher and Lecturer in Electrical Engineering and Computer Science (EECS), University of California, Berkeley (UC Berkeley). From 2004–2009, she was an Assistant Professor in the School of in Mechanical and Aerospace Engineering at Seoul National University (SNU), Seoul, Korea, where she is currently an Associate Professor. Her research interests include applications of nonlinear control theory and artificial intelligence for robotics, motion planning algorithms. Shankar Sastry received the B.Tech. degree from the Indian Institute of Technology, Bombay, in 1977, and the M.S. degree in EECS, the M.A. degree in mathematics, and the Ph.D. degree in EECS from UC Berkeley, in 1979, 1980, and 1981, respectively. He is currently Dean of the College of Engineering at UC Berkeley. He was formerly the Director of the Center for Information Technology Research in the Interest of Society (CITRIS). He served as Chair of the EECS Department from January, 2001 through June 2004. In 2000, he served as Director of the Information Technology Office at DARPA. From 1996 to 1999, he was the Director of the Electronics Research Laboratory at Berkeley (an organized research unit on the Berkeley campus conducting research in computer sciences and all aspects of electrical engineering). He is the NEC Distinguished Professor of Electrical Engineering and Computer Sciences and holds faculty appointments in the Departments of Bioengineering, EECS and Mechanical Engineering. Prior to joining the EECS faculty in 1983 he was a Professor with the Massachusetts Institute of Technology (MIT), Cambridge. He is a member of the National Academy of Engineering and Fellow of the IEEE.     

基于滑模观测器的直线伺服系统反馈线性化速度跟踪控制

在许多高速、高精的直线伺服系统中,要求能实现对速度的快速精确跟踪,但其模型的非线性和变量间的耦合给控制带来难度.对高速、高精速度跟踪控制中,电流和速度的变化过程在时间尺度上相对接近,不能简单地采用磁场定向矢量控制方法实现静态解耦,否则电流和速度间的非线性耦合将破坏速度跟踪品质.采用状态反馈线性化方法来实现永磁直线同步电动机(PMLSM)模型的精确线性化和动态解耦.利用非线性坐标变换和非线性反馈将系统解耦成独立的线性电流子系统和速度子系统.通过扩展滑模观测器来实现对所需要的动子速度、加速度和负载扰动的鲁棒观测.并利用李雅普诺夫理论对由反馈线性化和滑模观测器构成的非线性闭环系统的稳定性进行了证明.仿真结果表明该方案使PMLSM伺服系统具有良好的鲁棒速度跟踪性能.     

Extended state observer-based attitude fault-tolerant control of rigid spacecraft

In this paper, a novel fault-tolerant attitude tracking control is proposed for a rigid spacecraft with uncertain inertia matrix, actuator faults, actuator misalignment and external disturbances. The uncertainty of the inertial matrix is caused by the rotation of solar panels, payload movement and fuel consumption, and actuator faults, which include partially failed and completely failed actuators. A novel extended state observer is proposed to estimate the total uncertainties and a fast nonsingular terminal sliding-mode control scheme is proposed to get a faster, higher control precision. Strict finite-time convergence and the concrete convergence time are given. Finally, all the states of the closed-loop system are guaranteed to converge to the corresponding region in a finite time by choosing appropriate parameters. Simulation and comparison results further show the effectiveness and advantages of this method.     

Feedback linearization based control of a rotational hydraulic drive

The technique of feedback linearization is used to design controllers for displacement, velocity and differential pressure control of a rotational hydraulic drive. The controllers, which take into account the square-root nonlinearity in the system's dynamics, are implemented on an experimental test bench and results of performance evaluation tests are presented. The objective of this research is twofold: firstly, to present a unified method for tracking control of displacement, velocity and differential pressure; and secondly, to experimentally address the issue of whether the system can be modeled with sufficient accuracy to effectively cancel out the nonlinearities in a real-world system.     

Extended state observer for uncertain lower triangular nonlinear systems subject to stochastic disturbance

The extended state observer (ESO) is the most important part of an emerging control technology known as active disturbance rejection control to this day, aiming at estimating “total disturbance” from observable measured output. In this paper, we construct a nonlinear ESO for a class of uncertain lower triangular nonlinear systems with stochastic disturbance and show its convergence, where the total disturbance includes internal uncertain nonlinear part and external stochastic disturbance. The numerical experiments are carried out to illustrate effectiveness of the proposed approach.     

基于滑动窗实时小波降噪的扩张状态观测器及自抗扰控制EI北大核心CSCD

自抗扰控制技术应用已日渐成熟,但当系统中存在高频非平稳噪声信号时,线性自抗扰控制(LADRC)存在难以选取合适的观测器带宽的问题:当带宽较小时,线性扩张状态观测器(LESO)难以实现对总扰动的实时观测,会造成时滞;当带宽较大时,LESO又会放大噪声对系统的影响,从而造成总扰动观测失真.为了解决这一问题,将小波降噪环节加入LADRC中,通过设计基于滑动窗实时小波降噪的LESO,对含噪输出信号进行实时降噪.使用Simulink搭建系统模型,分别在输出信号中加入高斯白噪声或谐波等不同类型的高频非平稳噪声进行仿真实验,并将所提方法与滑动平均法进行对比,结果验证了所提方法的有效性.     

基于自适应模糊控制器和非线性扰动观测器的永磁直线同步电机反馈线性化控制

由于永磁直线同步电机(PMLSM)伺服系统应用于一些高精密场合,因此克服系统存在的负载扰动、参数变化等不确定性影响是提高系统性能的关键.针对不确定性问题,采用一种基于自适应模糊控制器(AFC)和非线性扰动观测器(NDO)的反馈线性化控制方法.首先设计反馈线性化控制器(FLC)实现系统的线性化,便于位置跟踪;其次采用ND...     

Extended state observer for MIMO nonlinear systems with stochastic uncertainties

ABSTRACT

In this paper, both linear extended state observer (ESO) and nonlinear ESO with homogeneous weighted functions are proposed for a class of multi-input multi-output (MIMO) nonlinear systems composed of coupled subsystems with large stochastic uncertainties. The stochastic uncertainties in each subsystem including internal coupled unmodelled dynamics and external stochastic disturbance without known statistical characteristics are lumped together as the stochastic total disturbance (extended state) of each subsystem. The linear ESO and nonlinear ESO are designed separately for real-time estimation of not only the unmeasured state but also the stochastic total disturbance of each subsystem. The practical mean square convergence of these two classes of ESOs are developed. Some numerical simulations are presented to demonstrate the effectiveness of the ESOs with the advantages of smaller peaking values and more accurate estimation by the nonlinear ESO.