基于干扰观测器的高超音速飞行器鲁棒反步控制

针对高超音速飞行器严格反馈不确定非线性MIMO系统,提出一种基于干扰观测器的鲁棒反步控制方法。该方法采用超扭曲算法设计干扰观测器以估计系统复合干扰,观测误差有限时间收敛。设计非线性反步控制律,引入鲁棒项使得系统满足干扰到性能输出的L2增益不超过设定的正实数,满足耗散不等式,使闭环系统跟踪误差一致最终有界稳定。仿真结果表明,所设计的控制律可以有效抑制系统复合干扰的影响,设计方法可行。     

飞行模拟转台非线性干扰观测器反步滑模控制器设计

本文针对考虑不确定性的飞行模拟转台伺服系统,提出了一种基于非线性干扰观测器的反步全局滑模补偿控制方法。该方法采用反步控制方法设计转速期望虚拟控制,然后利用非线性干扰观测器观测系统不确定干扰,进而对引入非线性干扰观测器的系统设计自适应全局滑模控制器,实现了飞行模拟转台伺服系统期望转角信号的鲁棒跟踪控制,仿真结果表明,该方法控制效果良好,具有很好的工程应用价值。     

近空间飞行器变增益非线性切换控制器设计

针对变后掠翼近空间飞行器大包络、多工作模态和模型不确定的特点,研究其模态切换过程中姿态的鲁棒跟踪控制问题.首先建立含扰动项的飞行器非线性切换模型,基于反步滑模方法和非线性干扰观测器设计鲁棒控制器,通过公共Lyapunov函数理论证明所设计的控制律能够保证闭环切换系统的稳定性;采用变增益切换控制策略为不同飞行模态设计合适的控制增益,用以提高系统的动态性能.仿真结果验证了所提出方法的有效性和必要性.     

考虑测量不确定和输入饱和的充液航天器自适应鲁棒控制

本文研究了三轴稳定充液航天器控制系统中同时存在测量不确定,外部未知干扰,参数不确定和控制输入饱和的鲁棒自适应姿态机动控制问题.建模过程中,将晃动液体燃料等效为粘性球摆模型,采用动量矩守恒定律推导出充液航天器的耦合动力学方程.提出了一种将反步控制方法结合非线性干扰观测器和指令滤波器的鲁棒饱和输出反馈复合控制策略,该控制策略不仅能继承反步控制方法的优点,而且通过引入非线性干扰观测器实现对未知外部干扰,参数不确定以及测量不确定的补偿,还能利用指令滤波器处理控制力矩输入饱和的不利影响.基于Lyapunov稳定性分析方法证明了系统状态变量的渐进稳定性.仿真结果验证了提出控制方法的有效性和鲁棒性.     

具有非线性不确定性的高超声速飞行器的 分布式鲁棒反步跟踪控制

本文针对具有外部干扰,参数摄动和非连续未知非线性气动影响的一般高超声速飞行器纵向动力学问题,设计了分布式鲁棒反步跟踪控制器.为了处理复杂的系统,将标准反步控制和信号补偿方法结合起来构成一个"简单"的鲁棒控制器.该方法不仅可以保证闭环系统半全局鲁棒跟踪性能,也可保证系统跟踪误差以期望的收敛速度收敛到期望的误差范围内.最后,带有非线性不确定性,外部干扰和参数扰动的仿真系统说明了该方法的有效性.     

具有非线性不确定性的高超声速飞行器的分布式鲁棒反步跟踪控制（英文）

本文针对具有外部干扰,参数摄动和非连续未知非线性气动影响的一般高超声速飞行器纵向动力学问题,设计了分布式鲁棒反步跟踪控制器.为了处理复杂的系统,将标准反步控制和信号补偿方法结合起来构成一个"简单"的鲁棒控制器.该方法不仅可以保证闭环系统半全局鲁棒跟踪性能,也可保证系统跟踪误差以期望的收敛速度收敛到期望的误差范围内.最后,带有非线性不确定性,外部干扰和参数扰动的仿真系统说明了该方法的有效性.     

基于反馈增益反步法欠驱动无人水下航行器三维路径跟踪控制

针对欠驱动无人水下航行器的三维空间路径跟踪控制问题.基于虚拟向导建立载体坐标系下的三维路径跟踪运动学误差模型,首先设计跟踪误差反馈增益形式的线性控制项镇定位置跟踪系统,避免计算虚拟控制量导数的复杂形式;然后基于反步法设计动力学控制器,通过合理的选择控制器参数消除了部分非线性项,简化了虚拟控制量的形式,同时避免了采用传统反步法设计控制器时存在的奇异值问题,基于李雅普诺夫稳定性理论设计鲁棒反馈补偿项,保证了闭环跟踪误差系统状态的一致最终有界.仿真实验表明本文设计控制器能够精确跟踪三维曲线路径,并对外界干扰具有较好的鲁棒性.     

基于神经网络MIMO非线性系统自适应输出反馈控制

针对一类具有对象不确定和外部干扰的MIMO(多输入多输出)非线性系统提出了自适应鲁棒输出跟踪控制方案.使用了高斯径向基神经网络自适应补偿对象非线性,高增益观测器被用来估计不能直接测量的输出导数.此方法所设计的控制器不仅保证闭环系统稳定,而且所有状态有界以及跟踪误差一致终值有界.仿真结果充分表明了该方案的有效性和可行性.     

未知死区输入非线性系统的双观测器动态面控制

针对一类含死区输入的严格反馈非线性系统,提出基于双观测器的自适应鲁棒控制算法.动态面的每一步设计中,第1观测器即跟踪信号观测器对指令信号进行观测,并得到指令信号的差分信号,消除传统动态面控制中计算复杂问题.第二观测器即扰动观测器在线估计高阶动态面控制系统中每一步的不确定模型,与跟踪信号观测器实现双反馈控制,提高控制效果.通过李雅普诺夫方法分析了自适应鲁棒控制器的输入输出有界的特性.最后,实验验证基于双观测器的自适应鲁棒控制器的性能,结果表明本文方法控制效果较好.且采用反双曲正弦函数建立观测器,参数调节少,利于工业应用.     

输入饱和与姿态受限的四旋翼无人机反步姿态控制

本文针对四旋翼无人机研究了鲁棒反步姿态控制策略.由于四旋翼无人机结构复杂,其非线性数学模型难以精确建立,因此在控制器设计过程中需要综合考虑模型不确定性、未知外部干扰、输入饱和以及姿态受限等因素.针对模型中的不确定项,使用神经网络进行逼近;对于外部未知干扰,使用非线性干扰观测器进行补偿;使用双曲正切函数逼近饱和函数,解决输入饱和问题;同时使用界限Lyapunov函数设计控制器,确保姿态满足限制条件.最后,设计四旋翼无人机反步姿态控制器,并根据Lyapunov稳定性定理证明了闭环控制系统的有界稳定.仿真结果表明了所研究控制方法的有效性.     

Robust control of nonlinear semi‐strict feedback systems using finite‐time disturbance observers

The output tracking controller design problem is dealt with for a class of nonlinear semi‐strict feedback systems in the presence of mismatched nonlinear uncertainties, external disturbances, and uncertain nonlinear virtual control coefficients of the subsystems. The controller is designed in a backstepping manner, and to avoid the shortcoming of ‘explosion of terms’, the dynamic surface control technique that employs a group of first‐order low‐pass filters is adopted. At each step of the virtual controller design, a robust feedback controller employing some effective nonlinear damping terms is designed to guarantee input‐to‐state practical stable property of the corresponding subsystem, so that the system states remain in the feasible domain. The virtual controller is enhanced by a finite‐time disturbance observer that estimates the disturbance term in a finite‐time. The properties of the composite control system are analyzed theoretically. Furthermore, by exploiting the cascaded structure of the control system, a simplified robust controller is proposed where only the first subsystem employs a disturbance observer. The performance of the proposed methods is confirmed by numerical examples. Copyright © 2017 John Wiley & Sons, Ltd.     

Robust nonlinear control of a three-tank system using finite-time disturbance observers

A finite-time disturbance observer-based robust control method is proposed for output tracking of the Inteco threetank system in the presence of mismatched uncertainties. The controller is designed in a backstepping manner. At each step of the virtual controller design, a robust feedback controller with some effective nonlinear damping terms is designed so that the system states remain in the feasible domain. The nonlinear uncertainty is compensated by a finite-time disturbance observer. And to avoid the shortcoming of “explosion of terms”, the dynamic surface control technique which employs a low-pass filter is adopted at each step of the virtual controller design. Attention is paid to reducing the measurement noise effects and to initialization technique of the system states and reference output trajectory. Theoretical analysis is performed to clarify the control performance. And the theoretical results are verified based on the experimental studies on the real Inteco three-tank system.     

基于干扰观测器的一类不确定仿射非线性系统有限时间收敛backstepping控制

针对一类不确定仿射非线性系统的跟踪控制问题,提出一种基于干扰观测器的有限时间收敛backstepping控制方法.为增强小脑模型(CMAC)泛化和学习能力,将非对称高斯函数和模糊理论相结合,给出非对称模糊CMAC结构,设计干扰观测器实现系统未知复合干扰在线准确逼近;基于非对称模糊CMAC干扰观测器,给出有限时间收敛backstepping控制器设计步骤,利用Lyapunov稳定理论证明闭环系统稳定性,其中采用非线性微分器获取虚拟控制量滤波和微分信息以避免backstepping设计中的微分“膨胀问题”,设计辅助系统修正因微分器带来的误差对系统跟踪性能影响,引入基于障碍型函数的自适应滑模鲁棒项抑制复合干扰估计偏差对跟踪误差的影响;将所提方法应用于无人机飞行控制仿真实验,结果表明所提方法的有效性.     

Adaptive integral backstepping sliding mode control for opto-electronic tracking system based on modified LuGre friction model

In order to improve the control accuracy and stability of opto-electronic tracking system fixed on reef or airport under friction and external disturbance conditions, adaptive integral backstepping sliding mode control approach with friction compensation is developed to achieve accurate and stable tracking for fast moving target. The nonlinear observer and slide mode controller based on modified LuGre model with friction compensation can effectively reduce the influence of nonlinear friction and disturbance of this servo system. The stability of the closed-loop system is guaranteed by Lyapunov theory. The steady-state error of the system is eliminated by integral action. The adaptive integral backstepping sliding mode controller and its performance are validated by a nonlinear modified LuGre dynamic model of the opto-electronic tracking system in simulation and practical experiments. The experiment results demonstrate that the proposed controller can effectively realise the accuracy and stability control of opto-electronic tracking system.     

Robust Tracking Control of Helicopters Using Backstepping with Disturbance Observers

This paper addresses the robust and accurate trajectory tracking problem for unmanned helicopters in the presence of model uncertainties and external disturbances. First, the helicopter's model is simplified to a six‐degrees‐of‐freedom rigid body augmented with a simplified rotor dynamic model, with the model uncertainties and the external disturbances being treated as lumped unknown disturbances. Second, a nonlinear disturbance observer is designed to estimate this lumped disturbance. Then, a backstepping controller with disturbance compensation is designed to ensure robust and highly trajectory tracking. After that, the theoretical analysis of the efficiency of the designed disturbance observer‐based backstepping controller (Backstepping+DO) is shown by the Lyapunov theory. Finally, simulation results and conclusions are presented and discussed.     

Time‐varying input delay compensation for nonlinear systems with additive disturbance: An output feedback approach

This paper addresses the output feedback tracking control of a class of multiple‐input and multiple‐output nonlinear systems subject to time‐varying input delay and additive bounded disturbances. Based on the backstepping design approach, an output feedback robust controller is proposed by integrating an extended state observer and a novel robust controller, which uses a desired trajectory‐based feedforward term to achieve an improved model compensation and a robust delay compensation feedback term based on the finite integral of the past control values to compensate for the time‐varying input delay. The extended state observer can simultaneously estimate the unmeasurable system states and the additive disturbances only with the output measurement and delayed control input. The proposed controller theoretically guarantees prescribed transient performance and steady‐state tracking accuracy in spite of the presence of time‐varying input delay and additive bounded disturbances based on Lyapunov stability analysis by using a Lyapunov‐Krasovskii functional. A specific study on a 2‐link robot manipulator is performed; based on the system model and the proposed design procedure, a suitable controller is developed, and comparative simulation results are obtained to demonstrate the effectiveness of the developed control scheme.     

基于非线性干扰观测器的高超声速飞行器滑模反演控制

针对高超声速飞行器非线性、强耦合和参数不确定弹性体模型,提出了一种基于非线性干扰观测器的滑模反演控制方法.将飞行器曲线拟合模型分解为速度子系统和高度相关子系统并表示为严格反馈形式,分别采用滑模和反演方法设计实际控制量与虚拟控制量.采用1阶低通滤波器获取虚拟控制量的导数,解决了传统反演控制方法"微分项膨胀"问题.基于改进滑模微分器设计了一种新型非线性干扰观测器,以此对模型不确定项进行估计和补偿.仿真结果表明,该控制器对模型不确定性和气动弹性影响具有鲁棒性,且实现了对速度和高度参考输入的稳定跟踪.     

一类非线性欠驱动移动系统的加速度反馈增强的H∞扰支抑制控制

In this paper, a generalized acceleration feedback control (AFC) design method, named AFC enhanced H∞ controller, is proposed for both fnllactuated and underactuated nonlinear autonomous vehicle systems. The AFC is designed as a robust enhancement to the normal control based on known dynamics. First, in order to reject the uncertainties and external disturbances, a linear prefilter is used in the new AFC design method to replace the high gain in the normal AFC. Then, backstepping algorithm is applied to the AFC design of underactuated systems. The analysis of both the disturbance attenuation in frequency domain and input-output finite gain L2 stability shows the new controller design method is applicable. In the end, simulations are conducted with respect to the tracking control of unmanned model helicopter. The results are compared with those obtained by the tracking control without AFC to verify the feasibility of the new method.     

基于干扰观测器的一类不确定非线性系统鲁棒H∞控制

为了降低控制器对干扰的要求,基于干扰观测器提出一类多输入多输出不确定非线性系统的鲁棒H∞控制方法．将系统的内部不确定性和外部干扰组成复合干扰,设计基于小波神经网络的复合干扰观测器,并提出干扰观测器的参数调节方案使观测器能以高精度逼近复合干扰．同时在控制器中引入鲁棒控制项用来抑制观测器误差给系统带来的影响,所设计的控制器能使系统的跟踪误差小于一个给定的性能指标．最后给出一个仿真算例验证了本控制方案的有效性．     

高超声速飞行器非线性鲁棒控制律设计

高超声速飞行器具有模型非线性程度高、耦合程度强、参数不确定性大、抗干扰能力弱等特点,其自主控制具有较大的挑战.论文提出了一种基于鲁棒补偿技术和反馈线性化方法的非线性鲁棒控制方法.文中首先采用反馈线性化的方法对纵向模型进行输入输出线性化,实现速度和高度通道的解耦和非线性模型的线性化.针对得到的线性模型,设计包括标称控制器和鲁棒补偿器的线性控制器.基于极点配置原理,设计标称控制器使标称线性系统具有期望的输入输出特性,利用鲁棒补偿器来抑制参数不确定性和外界扰动对于闭环控制系统的影响.基于小增益定理,证明了闭环控制系统的鲁棒稳定性和鲁棒跟踪性能.相比于非线性回路成形控制方法,仿真结果表明了所设计非线性鲁棒控制算法的有效性和优越性.