New model reference adaptive control with input constraints

A new scheme of adaptive control is proposed for a class of linear time-invariant（ LTI） dynamical systems,especially in aerospace,with matched parametric uncertainties and input constraints. Based on a typical and conventional direct model reference adaptive control scheme,various modifications have been employed to achieve the goal. ＂C omposite model reference adaptive control＂of higher performance is seam-lessly combined with ＂positive μ-mod＂,which consequently results in a smooth tracking trajectory despite of the input constraints. In addition,bounded-gain forgetting is utilized to facilitate faster convergence of parameter estimates. The stability of the closed-loop systemcan be guaranteed by using Lyapunov theory.The merits and effectiveness of the proposed method are illustrated by a numerical example of the longitudinal dynamical systems of a fixed-wing airplane.

Multimodel-based flight control system reconfiguration control in the presence of input constraints

In this paper,an active fault accommodate strategy is proposed for the plant in the presence of actuator fault and input constraints,which is a combination of a direct adaptive control algorithm with multiple model switching.The μ-modification is introduced in the model reference architecture to construct the adaptive controller.The proof of stability is based on the candidate Lyapunov function,while appropriate switching of multiple models guarantees asymptotic tracking of the system states and the boundedness of all signals.Simulation results illustrate the efficiency of the proposed method.

MULTIVARIABLE MODEL REFERENCE ADAPTIVE CONTROL FOR A TURBOFAN ENGINE

A decentralized model reference adaptive control (MRAC) scheme is proposed and applied to design a multivariable control system of a dual-spool turbofan engine.Simulation studies show good static and dynamic performance of the system over the fullflight envelope. Simulation results also show the good effectiveness of reducing interactionin the multivariable system with significant coupling. The control system developed has awide frequency band to satisfy the strict engineering requirement and is practical for engineering applications.

Novel robust fault diagnosis method for flight control systems

A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model （AMM） and unknown input observer （UIO）. The main idea of the proposed scheme stems from the fact that the actuator Lock-in-Place fault is unknown （when and where the actuator gets locked are unknown）, and multiple models are used to describe different fault scenarios, then a bank of unknown input observers are designed to implement the disturbance de-coupling. According to Lyapunov theory, proof of the robustness of the newly developed scheme in the presence of faults and disturbances is derived. Numerical simulation results on an aircraft example show satisfactory performance of the proposed algorithm.

Control Design for Harmonic Disturbance Rejection for Robot Manipulators with Bounded Inputs

Currently most of control methods are of one degree of freedom（1-DOF） control structure for the robot systems which are affected by unmeasurable harmonic disturbances,at the same time in order to obtain perfect disturbance attenuation level,the controller gain must be increased.In practice,however,for robotic actuators,there are physical constraints that limit the amplitude of the available torques.This paper considers the problem of tracking control under input constraints for robot manipulators which are affected by unmeasurable harmonic disturbances.A new control scheme is proposed for the problem,which is composed of a parameter-dependent nonlinear observer and a tracking controller.The parameter-dependent nonlinear observer,designed based on the internal model principle,can achieve an estimation and compensation of a class of harmonic disturbances with unknown frequencies.The tracking controller,designed via adaptive control techniques,can make the systems asymptotically track the desired trajectories.In the control design,the continuous piecewise differentiable increasing function is used to limit control input amplitude,such that the control input saturation is avoided.The Lyapunov stability of closed loop systems is analyzed.To validate proposed control scheme,simulation results are provided for a two link horizontal robot manipulator.The simulation results show that the proposed control scheme ensures asymptotic tracking in presence of an uncertain external disturbance acting on the system.An important feature of the methodology consists of the fact that the designed controller is of 2-DOF control structure,namely,it has the ability to overcome the conflict between controller gain and robustness against external disturbances in the traditional 1 -DOF control structure framework.

Modified robust optimal adaptive control for flight environment simulation system with heat transfer uncertainty

To solve the rapid transient control problem of Flight Environment Simulation System(FESS) of Altitude Ground Test Facilities(AGTF) with large heat transfer uncertainty and disturbance, a new adaptive control structure of modified robust optimal adaptive control is presented.The mathematic modeling of FESS is given and the influence of heat transfer is analyzed through energy view. To consider the influence of heat transfer in controller design, we introduce a matched uncertainty that represents heat transfer influence in the linearized system of FESS. Based on this linear system, we deduce the design of modified robust optimal adaptive control law in a general way. Meanwhile, the robust stability of the modified robust optimal adaptive control law is proved through using Lyapunov stability theory. Then, a typical aero-engine test condition with Mach Dash and Zoom-Climb is used to verify the effectiveness of the devised adaptive controller. The simulation results show that the designed controller has servo tracking and disturbance rejection performance under heat transfer uncertainty and disturbance;the relative steady-state and dynamic errors of pressure and temperature are both smaller than 1% and 0.2% respectively. Furthermore,the influence of the modification parameter c is analyzed through simulation. Finally, comparing with the standard ideal model reference adaptive controller, the modified robust optimal adaptive controller obviously provides better control performance than the ideal model reference adaptive controller does.

存在输出受限的高速列车自适应防滑控制

针对高速列车运行时存在车轮打滑的问题,提出一种将输出受限与模型参考自适应控制(model reference adaptive control, MRAC)相结合的防滑控制策略。该策略在障碍李雅普诺夫函数(barrier Lyapunov function, BLF)和MRAC算法作用下,可较好地实现防滑控制。首先,根据列车黏着原理建立动力学模型,再将黏着防滑问题转化为包含输出受限的蠕滑速度跟踪控制问题;其次,凭借BLF的约束能力以及MRAC特性,设计自适应防滑控制器;最后,证明该控制系统的稳定性。仿真实验表明,所设计的控制策略实现了对蠕滑速度曲线的渐近跟踪控制和列车防滑控制,且收敛速度快、跟踪误差小、防滑效果好,验证了该防滑控制策略的有效性。

飞机纵向运动模型参考反推自适应PID控制

为克服飞行控制系统设计中传统增益规划方案的缺点,提出一类飞机纵向运动模型参考反推自适应PID控制方案,并给出了该方案的具体设计过程和跟踪性能改善方法.理论分析和数值仿真结果表明,该方案兼具反推自适应控制和PID控制的优点,即:无需知道被控对象的精确数学模型,控制器结构简单,鲁棒性强,在不增大控制增益的前提下具有良好的跟踪性能.

一种约束输入的广义预测控制新算法

提出一种约束输入的广义预测控制新算法 (GPCIC) ,该算法不必求逆矩阵 ,占用内存小 ,计算速度快。仿真结果表明 。

基于模型参考自适应方案的飞行器增稳控制研究

文中应用模型参考自适应理论设计飞行器纵向增稳控制系统,阐述了建立高品质参考模型及应用超稳定性理论设计增稳控制律的方法。利用超稳定性设计方法能够获得一簇自适应控制律,设计者可从中选择以获得理想的控制性能。仿真结果表明,自适应飞行器增稳控制系统性能良好。

大侧滑模型参考自适应飞行控制方法研究

针对飞机单侧副翼舵机卡死故障的飞行问题,研究了基于模型参考自适应控制的大侧滑角飞行控制方法。首先给出进行大侧滑角直飞的级联式飞行控制方案,并对控制信号间的关系进行分析;其次对与侧滑角指令有关的姿态内环进行模型参考自适应控制结构和算法设计,同时给出参考模型选取方法;最后分别在无故障和单侧副翼舵机卡死飞机下进行非线性仿真验证。仿真结果表明,该控制方法能够在气动数据摄动和控制器参数初值随意选取下,仅利用故障前配平点使得飞机在发生单侧副翼舵机卡死后能够跟随参考模型响应,并进一步无静差地跟踪大侧滑角指令,具有较好的鲁棒性和实用性。

基于主-辅控制架构的无人机鲁棒飞行控制律设计

无人机在实际飞行中易受到扰动与系统未建模动态等不确定性因素的影响.为此,文中提出了一种新的鲁棒飞行控制律设计方法.该方法以主-辅控制器为基本架构,主控制器采用鲁棒伺服线性二次型调节(LQR)法构造,以提供基本指令跟踪控制输入;以加入主控制器后的理想闭环系统为参考模型,基于鲁棒模型参考自适应算法设计辅控制器,以抑制扰动和未建模动态对飞行控制系统的影响.理论分析表明,该控制律能够保证闭环飞行控制系统在存在有界扰动与未建模动态情况下稳定且跟踪误差有界.非线性对比仿真验证了控制系统对各种形式扰动的抑制作用,说明了该控制系统的有效性与鲁棒性.

模型参考自适应电传飞行控制系统纵向控制律设计

针对电传飞行控制系统中被控对象模型参数时变的特点,应用模型参考自适应控制方法设计纵向控制律。论述飞机纵向运动的动力学模型和参考模型的建立,以及基于此参考模型用超稳定性理论设计自适应控制律的方法,并且通过仿真试验进行控制性能验证。仿真结果表明,所设计的控制律可以根据飞行状态的不同自适应的调节控制律,控制性能指标满足飞行品质规范要求,设计方法可行。

变结构自适应控制在BTT导弹中的应用

提出了ＢＴＴ导弹自动驾驶仪的变结构自适应设计方法。该方法完全基于对象参数变化和随机扰动的上下界，无需对系统进行参数辩识和对随机扰动进行在线估计，增强了控制系统的适应性和鲁棒性。在考虑了各种非理想因素的情况下，得到了令人满意的仿真结果。

基于MRAC理论的大型机场航班控制研究

中国民航运输业目前遇到的突出问题是航班延误。虽然飞机飞行处于严格监管具备典型离散事件动态系统属性,但在合理条件设置的基础上可以将航班运行过程转化后运用连续时间动态系统理论处理。以大型机场航班进港间隔控制过程为例,基于实测数据对航班进港间隔控制系统动态过程的模型参数进行辨识,并应用模型参考自适应控制方法设计机场终端区航班控制策略。根据飞机进港序列数据特征,产生伪随机序列进行仿真研究,结果表明飞机进港序列间隔方差明显减小,进港过程平稳。这为缓解航班延误,特别是大型机场终端区航班流量管理辅助决策提供了新的思路。

考虑饱和的舵机自适应控制系统

针对某飞行器舵机系统中饱和非线性造成的不良影响，研究了一种模型参考自适应控制方案后，对舵机系统进行了自适应改进设计，并将其应用于此飞行器纵向控制系统中。仿真结果表明，这种自适应舵机系统不仅能提高飞行性能。

基于神经网络的模型参考自修复飞行控制

提出了一种基于模糊神经网络的模型参考自修复飞行控制结构,并对所使用的BP网络学习算法进行了分析改进。对比非故障和故障状态下的飞行仿真结果表明,改进后的自修复飞行控制方法可以有效地抑制神经网络的“过学习”现象,减小了对神经网络辨识器精度的依赖程度,在故障条件下的补偿作用非常明显,达到了自修复飞行控制的目的。

基于模型参考自适应方法的直升机悬停控制

为研究三自由度直升机实验教学模型的运动特性,建立了小型三自由度直升机系统的数学模型,将直升机模型的运动分为俯仰轴、横侧轴、旋转轴三个部分,并分别建立动力学方程;针对该直升机模型的悬停控制问题,设计了基于Lyapunov稳定性理论的模型参考自适应控制系统,使得直升机姿态控制能达到期望的要求。仿真结果表明,设计的控制系统能同时满足动态和稳态性能指标,为利用该方法进行其他控制系统的设计提供了参考。

具有任意非线性输入的鲁棒模型参考自适应控制

提出了一种分析具有任意非线性输入的模型参考自适应（ＭＲＡＣ）的新方法，它不要求对象是稳定的，允许系统存在未建模动态和有界扰动．同时给出了一种提高非线性输入自适应系统特性的补偿方案，它通过在控制律中引入跟踪误差，可以提高系统的暂态及稳态精度。

离散MRACS设计的一种改进方法

本文只用输入输出测量值设计了一种全局稳定离散模型参考自适应控制系统。与文献[2]相比,作了三点改进:少用了一组滤波器;将可测负载扰动L(k)的未知增益项扩展成多项式形式;去掉了控制输入up(k)表达式中存在的可调参数_0(k)的除数项。