高超声速飞行器轨迹跟踪的反步滑模控制

针对高超声速飞行器轨迹跟踪控制问题,基于纵向动力学的输入/输出线性化模型,设计了一种基于反步法与滑模控制相结合的反步滑模跟踪控制器;这种控制器对系统匹配不确定性和非匹配不确定性都具有较强的鲁棒性,跟踪收敛快速性良好;对反步滑模跟踪控制器和一般滑模跟踪控制器进行了控制参数仿真优化,对比研究了速度跟踪、高度跟踪、速度高度同时跟踪和正弦速度跟踪条件下两种控制器的快速性和鲁棒性,证实了文章方法的有效性。     

基于VTOL飞行器的滑模控制器设计

垂直起降(Vertical takeoff and landing,VTOL)飞行器是具有3个自由度、2个控制输入的非线性欠驱动控制系统,为了解决严重耦合的VTOL欠驱动系统的输出跟踪问题,首先将VTOL动力学模型解耦成一个最小相位系统和一个非最小相位系统,然后分别针对这两个解耦子系统设计滑模控制器,并通过Lyapunov理论证明系统的稳定性,最后仿真结果表明所设计的滑模控制器实现了对轨迹的无稳态误差跟踪,具有较好的鲁棒性,能够为此类欠驱动系统的输出跟踪问题提供设计参考。     

基于线性化反馈的滑模变结构重装空投纵向控制律设计

针对重装空投过程中,重型货物持续移动及瞬间离机严重影响载机的安全性等问题,提出了基于线性化反馈和滑模变结构控制相结合的控制律设计方法,利用非线性多输入多输出反馈线性化完成系统解耦线性化,在此基础上采用滑模变结构控制设计系统内环速度与俯仰姿态跟踪控制器,保证了系统鲁棒性,结合外环PID高度保持控制器完成整个飞行控制系统的设计.最后,仿真验证了该控制器鲁棒性强,且满足空投任务战技指标要求.     

基于时变增益的临近空间飞行器鲁棒控制

临近空间飞行器具有多输入多输出、非线性、强耦合及参数不确定等特点,针对传统滑模控制方法应用于临近空间飞行器模型时存在的控制抖振问题,设计了一种可削弱控制抖振的非线性鲁棒控制方法.该控制方法利用滑模控制设计思路,针对速度及高度输出,结合动态逆方法分别设计解耦滑模面,同时利用Lyapunov稳定性概念设计时变的反馈增益,代替传统滑模控制方法中不连续的符号函数,有效的削弱了控制量抖振.仿真结果表明,该方法能够在削弱控制量抖振的同时,达到良好的跟踪性能和鲁棒性能,具有较好的应用价值.     

四旋翼无人飞行器的轨迹跟踪与滑模事件驱动控制

四旋翼飞行器作为一个典型的欠驱动的系统,具有强耦合、非线性等特性.针对飞行器外部干扰、和通信资源受限条件下的轨迹跟踪控制问题,进行滑模事件驱动控制方法的研究.首先,分析动力学特性,通过时间尺度分解方法将系统解耦成位置子系统和姿态子系统.其次,将位置子系统转化为严格反馈形式,设计反步滑模控制器,实现位置轨迹稳定跟踪;针对姿态子系统存在时变有界扰动及通信受限,设计滑模事件驱动控制律,在抑制干扰的同时实现对虚拟姿态跟踪指令的跟踪.根据Lyapunov分析方法证明了所设计控制器的稳定性,并通过理论分析证明闭环控制系统不会出现Zeno现象.最后,仿真结果验证了滑模事件驱动控制律在存在外部扰动和通信受限时四旋翼无人飞行器轨迹跟踪的鲁棒性.     

运输机重装空投二阶终端滑模控制方法研究

针对重装空投过程中,货物的持续移动及瞬间出舱影响空投任务完成性、威胁飞行安全等问题,提出了一种二阶终端滑模纵向飞行控制方法;该方法利用非线性多输入多输出反馈线性化完成系统解耦线性化,在此基础上采用二阶终端滑模变结构控制设计系统内环速度与俯仰姿态跟踪控制器,保证了系统鲁棒性,结合外环PID高度保持控制器完成了整个飞行控制系统的设计;数值仿真结果表明,该系统具有良好的响应特性,且对系统不确定性具有较强的鲁棒性。     

时变终端滑模自适应有限时间控制算法

为实现非线性系统输出对期望轨迹的有限时间内精确跟踪，提出一种有限时间鲁棒控制算法。通过设计一种无到达过程的时变终端滑模面，在保证有限时间收敛的基础上，消除了传统滑模控制中固有的稳态误差，实现系统输出对期望轨迹的精确跟踪。设计了自适应更新律补偿由参数摄动导致的系统扰动，增强系统对内部未知参数摄动的鲁棒性。对比仿真结果表明：时变终端滑模控制比线性滑模控制的轨迹跟踪时间快41.5%；线性滑模控制器下的轨迹跟踪稳态误差为0.005，时变滑模控制器使轨迹跟踪的稳态误差降为0，实现精确跟踪。     

微型飞行器的自抗扰控制器设计

微型飞行器具有高度的非线性特性,且气动参数具有不确定性,难以建立精确的数学模型;为实现其姿态、速度、以及高度的精确鲁棒控制,基于自抗扰控制方法设计了微型飞行器速度回路和高度回路的控制器;首先建立了微型飞行器的非线性模型,然后利用扩张状态观测器对飞行器状态和气动不确定性因素进行了估计,并通过非线性反馈对模型不确定性部分和状态耦合进行补偿,实现了纵向通道的解耦控制;通过仿真对所设计的控制器进行性能验证,结果表明自抗扰控制器能够实现对微型飞行器的快速稳定控制,且不依赖于精确的飞行器数学模型,具有良好的鲁棒性。     

基于变结构动态逆控制的平流层飞艇时间最优航迹设计

解决平流层飞艇自主航行的首要问题就是航迹规划。飞艇模型具有高度非线性,因此利用动态逆控制理论,通过非线性反馈和动态补偿实现飞艇非线性系统精确线性化,以方便使用庞特里亚金极小值原理设计飞艇时间最优航迹。同时以动态逆控制作为控制内环,以滑模变结构控制作为控制外环,设计双层结构的变结构动态逆航迹跟踪控制系统,实现对飞艇理想航迹的跟踪。该方法将动态逆控制的非线性解耦能力、变结构控制的鲁棒性能与庞特里亚金极小值原理有机结合,可以用来解决平流层飞艇定点悬停控制、悬停点间机动控制等问题,具有很好的工程实用价值。     

高超飞行器的再入非线性鲁棒控制

针对再入段高超飞行器非线性动力学模型存在不确定性和干扰,基于奇异摄动理论提出了鲁棒变结构+动态逆内外环解耦控制方法.为避免在线实时求逆,控制系统的外环基于简化的模型设计自适应滑模变结构控制律,通过反馈干扰观测器在线估计广义干扰量,实现角度的跟踪和闭环系统的稳定,抑止外来干扰.强耦合的姿态动力学内环采用动态逆跟踪角速度指...     

Stable inversion for nonlinear discrete-time systems

We solve the exact output tracking problem for square nonlinear discrete-time systems through stable inversion. This stable inversion problem involves finding a bounded solution of a dynamical system driven by a bounded signal. Such a solution is given by a difference representation formula, whose existence, under the proper assumptions, can be proven using a Picard process     

基于LMI的参数随机变化系统的概率密度函数控制

针对模型参数在有界区域内随机变化的系统, 基于平方根 B 样条模型, 提出了输出概率密度函数 (Probability density function, PDF) 跟踪控制策略. 目标是控制系统输出的概率密度函数跟踪给定的概率密度函数. 通过 B 样条逼近建立了输出 PDF 和权值之间的对应关系, 把 PDF 的跟踪转化为权值的跟踪, 同时系统转化为 MIMO 系统,从而权值向量的跟踪就转化为 MIMO 系统的跟踪问题, 接着给出了系统输出概率密度函数跟踪给定概率密度函数的控制器存在的充分条件, 通过求解线性矩阵不等式完成状态反馈和输出反馈跟踪控制器的设计, 得到了系统具有 Hinfinity 范数界 Gamma 鲁棒镇定的结果. 仿真结果表明本文提出的控制算法是有效的.     

Generalized feedforward tuning rules for non-realizable delay inversion

This paper describes the problem of load disturbance rejection using feedforward for the case when perfect compensation is not realizable due to processes delays inversion. First, a new generalized open-loop design tuning rule for feedforward compensators is proposed. Simple and intuitive guidelines are given for aggressive, moderate, and conservative performance results. Moreover, a switching feedforward compensator is proposed to be used when oscillations are not allowed in the process output. Simulation results show important improvements in disturbance rejection, reference tracking error and control effort.     

Stable inverse control for nonminimum-phase nonlinear processes

Since most of the chemical processes happen to be nonlinear, nonlinear controllers with feedback linearization have been recently designed which can directly cancel the nonlinearities and establish a linear input/output map. However, this I/O linearization algorithm requires the control with stable inversion and state feedback. In the present study, a stable inversion technique for nonminimum-phase systems is developed under appropriate assumptions, which includes several steps such as finding the bounded control and bounded state trajectories for tracking the desired signal. In this design, the output tracking error as well as the effect of measurable disturbances can be asymptotically eliminated through generating a feedforward control. Finally, the proposed control methodology is applied to a chemical process, viz. a Van de Vusse reaction in an isothermal or adiabatic stirred-tank reactor, and its performance is evaluated.     

Inversion-based optimal output tracking–transition switching with preview for nonminimum-phase linear systems

In this article, the problem of nonperiodic tracking–transition switching with preview is considered. Such a control problem exists in applications including nanoscale material property mapping, robot manipulation, and probe-based nanofabrication, where the output needs to track the desired trajectory during the tracking sections, and rapidly transit to another point during the transition sections with no post-transition oscillations. Due to the coupling between the control of the tracking sections and that of the transition ones, and the potential mismatch of the boundary system state at the tracking–transition switching instants, these control objectives become challenging for nonminimum-phase systems. In the proposed approach, the optimal desired output trajectory for the transition sections is designed through a direct minimization of the output energy, and the needed control input that maintains the smoothness of both the output and the system state across all tracking–transition switching is obtained through a preview-based stable-inversion approach. The needed preview time is quantified by the characteristics of the system dynamics, and can be minimized via the recently developed optimal preview-based inversion technique. The proposed approach is illustrated through a nanomanipulation example in simulation.     

Time and output warping of control systems: Comparing and imitating motions

The problem of making one system “mimic” a motion generated by another is studied. To address this, an optimal tracking problem is introduced that, in addition to tracking, optimizes over functions that deform or “warp” the time axis and the output space. Parametric and nonparametric versions of the time-warped tracking problem are presented and reduced to standard Bolza problems. The output warping problem is treated for affine and piecewise affine output warping functions. Example applications are given, including that of controlling a marionette to mimic a human dancer.     

Dynamic hybrid control of cooperating robots by nonlinear inversion

The manipulation of a rigid object by two cooperating robots is considered. If only the position of the object is of interest, the inverse dynamic problem is redundant, because the number of available actuators exceeds the number of degrees of freedom of the object. Introducing the internal force developed in the object as a controlled quantity removes this redundancy. In the present formulation the system is viewed as a closed mechanical chain, but with elastic restraint between the object and the hands of the robots. The inclusion of this compliance in the mathematical model makes it possible to have the internal force as an output of the system and to solve the inverse dynamic problem taking it into account. A solution is derived based on nonlinear inversion. It is shown that the system has relative or tracking order four, and a left-inverse system, which has as input the object position and the internal force and as output the actuator torques, is constructed.     

Dynamic inversion for multivariable non-affine-in-control systems via time-scale separation

This paper presents a tracking design methodology applicable to multivariable non-affine-in-control systems. The main focus is on solving the tracking problem for non-linear systems whose dynamics depend non-linearly on the control input. The latter is designed to be faster than the main system dynamics. Using singular perturbation theory along with the Lyapunov stability theorems, it is shown that the proposed controller approximates an unknown dynamic inversion based solution with bounded errors, provides closed-loop stability, and solves the tracking problem with bounded errors. Simulations illustrate the theoretical results.     

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.     

Output tracking control of nonlinear switched cascade systems using a variable structure control method

This article is concerned with the output tracking control problem for a class of nonlinear switched cascade systems under some average dwell-time-based switching laws. Firstly, stabilisation problem of this class of switched systems is considered. Then, the result is extended to the output tracking control problem. Based on the variable structure control technique and the characteristic of the system, the variable structure controllers and the average dwell-time are designed. The effectiveness of the proposed design approach is illustrated with simulation results.