基于系统非线性因素的阵风载荷减缓技术研究

随着大型客机电传飞控的引入,系统非线性问题逐渐突显。对于阵风载荷减缓系统而言,非线性因素往往会严重影响阵风减缓效果。采用有限元和偶极子网格方法建立气动弹性模型,并分析其实际工程中主要的系统非线性因素,包括饱和、速率限制与延迟。其次,根据机载设备探测的阵风信息,以翼尖加速度、翼根剪力和弯矩作为阵风减缓指标,设计了阵风预测以及自适应前馈控制方案,从而弥补传统反馈控制中的不足性。最后,针对三种系统要求指标,分别与传统反馈控制进行减缓效率的对比分析。研究结果表明,系统的非线性因素对阵风减缓效果具有重大影响,且利用前方阵风探测信息设计的自适应前馈控制方案具备更好的阵风减缓效果。     

基于CMAC-PID并行控制的阵风减缓控制系统

针对高速飞机飞行在大气干扰下,产生强烈阵风干扰,飞机方程存在未建模扰动,传统PID难以保证控制稳定效果,提出了基于粒子群优化策略的CMAC-PID并行控制的直接升力控制方法,并将其应用于飞机阵风减缓控制系统的设计中.采用乘坐品质舒适指数作为适应度函数,通过粒子群优化,得到PID控制器参数为神经网络训练提高导师信号.在系统运行中,PID控制器输出逐渐趋近为零,CMAC网络控制输出逐步取代PID控制输出,成为控制器主要控制信号.仿真结果表明,提出的方法比传统PID控制器能够更加有效的起到阵风减缓效果增加稳定性.     

基于IM-PSO的大型民用客机载荷减缓控制研究

民用客机在垂直向紊流干扰下,会产生不期望的过载,导致乘坐品质下降。针对这一问题,提出了一种基于IM-PSO优化的载荷减缓控制设计方案。设计了控制副翼、扰流板和升降舵的载荷减缓控制系统,通过自动偏转副翼和扰流板,抵消阵风干扰带来的影响,并通过偏转升降舵,确保飞机的稳定控制。根据系统性能指标选择合适的参考模型,并设定合理的目标函数。最后,应用了IM-PSO算法进行控制器参数的自动寻优。仿真结果表明,基于IM-PSO优化的载荷减缓控制系统,能有效降低阵风干扰,改善飞机的乘坐舒适性,达到了良好的控制效果。     

一种近似解耦方法在飞机侧风减缓中的应用

采用一种基于输出反馈,部分状态反馈和奇异摄动理论的近似解耦方法设计一个高增益比例积分控制器来实现对多变量系统的解耦控制.所得控制器结构简单,且解耦后的系统能得到良好的动态响应和较强的鲁棒性.文中以经改装后具有直接侧力操纵面的某型飞机为例,对其侧向平移模态进行了解耦控制设计,并将其应用于该飞机的阵风减缓.最后与不具有直接侧力操纵面的原飞机进行仿真对比.仿真结果表明,其产生的均方根阵风加速度比原飞机减少了约55%.     

基于干扰估计的非对称运动下飞机刹车系统模型预测控制

针对飞机在非对称运动下的双侧机轮协调控制问题, 提出一种基于滑模干扰估计的模型预测控制方法. 首先, 通过对飞机制动过程横纵方向力矩机理分析并分别考虑左右机轮对刹车性能的影响, 建立全面刻画系统动态的地面滑跑动力学模型. 在此基础上, 设计滑模观测器对侧风干扰进行实时估计, 利用补偿机制实现对侧风扰动的有效抑制. 此外, 提出基于前轮荷载状态门限特征和结合系数阈值范围特征的分析方法, 解决切换跑道环境辨识问题. 设计非线性模型预测算法, 实现飞机纵向防滑刹车和横向跑道纠偏的协调控制. 最后, 在侧风干扰、跑道切换以及不对称着陆等情况下进行仿真实验, 验证了所提出的控制策略能够有效提升刹车系统的防滑效率及纠偏性能.     

采用最优状态估计的主蒸汽温度动态矩阵控制方法

针对主蒸汽温度控制系统不可测扰动影响的问题,提出一种基于最优状态估计的动态矩阵控制(OSE-DMC)算法.首先分析主蒸汽温度系统的动态特性,归纳出减温水量对主蒸汽温度影响的数学模型;然后基于常规DMC算法,利用最优估计理论对DMC算法的预测序列进行补偿修正,有效抑制不可测扰动的影响,并提出一种Kalman滤波的降维算法,使其计算更加简洁、便于实际应用与在线计算.Simulink仿真结果表明:在不可测扰动影响下,所提出方法抑制扰动效果比常规DMC算法提高20%,抑制扰动能力有显著提升.     

事件触发双模分布式预测控制

本文针对有界扰动作用下的线性离散大系统,提出了事件触发双模分布式预测控制设计方法.利用输入状态稳定性(input-to-state stability,ISS)理论建立了仅与子系统自身信息相关的事件触发条件.只有子系统满足相应的事件触发条件,才进行状态信息的传输和分布式预测控制优化问题的求解,并与邻域子系统交互最优解作用下的关联信息.当子系统进入不变集时,采用状态反馈控制律进行镇定,并与进入不变集的邻域子系统不再交互信息.分析了算法的递推可行性和系统的闭环稳定性,给出了扰动的上界.最后,通过车辆控制系统对算法进行仿真验证,结果表明,本文提出的方法能够有效降低优化问题的求解次数和关联信息的交互次数,节约计算资源和通信资源.     

时滞系统的状态预测观测器及预测控制器设计

研究基于状态空间模型的时滞控制系统的状态预测观测器及最优预测控制器的设计问题。针对控制项含有时滞的系统，设计一种全维状态预测观测器，并将其用于时滞控制系统的最优状态预测反馈控制。通过该状态预测观测器可将闭环系统的时滞项移至系统闭环结构之外，从而使其优化控制规律完全可按无时滞系统进行设计。所给出的性能指标计算公式表明，该预测控制器关于二次型性能指标是次优的。     

一类具有参数不确定n阶多输入多输出非线性系统的Terminal滑模控制

针对一类具有参数不确定的n阶MIMO非线性系统,提出了一种Terminal滑模控制方案.该方案通过对滑模超平面的选取和Terminal滑模控制律的设计,不但确保了闭环系统滑模阶段的存在性,而且还保证了系统状态误差在有限时间内的收敛性,由于无论何种情况下系统的初始状态均在Terminal滑模面上,从而消除了其他滑模控制方法常有的到达阶段,使得闭环系统具有全局鲁棒性和稳定性.除此之外,重点克服了控制输入的系数函数矩阵与不确定参数的关联问题.仿真结果表明,该控制方案可消除外部扰动及参数不确定的影响,控制系统各状态变量有效地跟踪期望状态.     

风扰影响下的无人机非线性广义最小方差跟踪控制

本文以鱼鹰型固定翼无人机为研究对象,基于非线性广义最小方差(nonlinear generalized minimum variance,NGMV)最优控制理论,研究了受到非线性阵风干扰影响下的无人机跟踪控制问题.首先对鱼鹰型无人机动力学模型解耦,在解耦后的横向和纵向模型上分别实现跟踪控制;然后针对阵风非线性模型的特定形式,根据NGMV理论设计了增维的非线性广义最小方差控制器,使得模型充分考虑了阵风干扰的特性.所设计的NGMV最优控制器的主要优势在于它能处理带有干扰和时滞环节的非线性系统.多组阵风扰动的仿真试验结果表明,非线性广义最小方差最优控制器具有跟踪性和收敛性.     

Stability analysis and design for aircraft gust alleviation control

This paper is concerned with the stability analysis and the development of an on-line two-level gust alleviation control system for a high-speed aircraft operating in an unknown environment. As is well known, such an aircraft experiences dynamic instability in its lateral motion when subjected to the longitudinal and lateral gusts. This is due to the phenomenon of lateral-longitudinal aerodynamic cross-coupling.In the first part of this paper the instability behaviour, in the presence of a longitudinal gust, of two typical high-speed aircraft is analyzed. From theoretical and simulation studies it is shown that for a sinusoidal gust, and for a given configuration, the instability region is a function of both the amplitude and frequency of the gust disturbance.In the second part of the paper, an on-line gust alleviation control system is synthesized for such an aircraft operating over a wide range of unknown environmental conditions. This control system employs a two-level control structure. The controller, however, does not require an explicit knowledge of the aircraft parameters or the environment. Typical simulation results are presented which verify the theoretical predictions.     

面向攻角变化的风洞流场模型预测控制器

目前已有的控制方法难以满足大飞机研制对风洞流场的精度要求.鉴于此,采用多变量模型预测控制方法设计流场控制器.为提高抵抗攻角扰动的能力,使用攻角变化量动态补偿静压的预测值.考虑风洞实验工况较多,采用多控制器融合方法解决新工况建立预测模型的问题.为保证控制器的实施,给出基于一阶惯性加滞后近似模型的控制器参数整定方法.通过实际吹风实验验证风洞预测控制器能够有效调节风洞流场,使吹风实验中流场参数的精度达到大飞机研制要求.     

Observer-based Adaptive Fuzzy Backstepping Tracking Control of Quadrotor Unmanned Aerial Vehicle Powered by Li-ion Battery

In this paper, an Adaptive Fuzzy Backstepping Control (AFBC) approach with state observer is developed. This approach is used to overcome the problem of trajectory tracking for a Quadrotor Unmanned Aerial Vehicle (QUAV) under wind gust conditions and parametric uncertainties. An adaptive fuzzy controller is directly used to approximate an unknown nonlinear backstepping controller which is based on the exact model of the QUAV. Besides, a state observer is constructed to estimate the states. The stability analysis of the whole system is proved using Lyapunov direct method. Uniformly Ultimately Bounded (UUB) stability of all signals in the closed-loop system is ensured. The proposed control method guarantees the tracking of a desired trajectory, attenuates the effect of external disturbances such as wind gust, and solves the problem of unavailable states for measurement. Extended simulation studies are presented to highlight the efficiency of the proposed AFBC scheme.     

A Novel Robust Attitude Control for Quadrotor Aircraft Subject to Actuator Faults and Wind Gusts

A novel robust fault tolerant controller is developed for the problem of attitude control of a quadrotor aircraft in the presence of actuator faults and wind gusts in this paper. Firstly, a dynamical system of the quadrotor taking into account aerodynamical effects induced by lateral wind and actuator faults is considered using the Newton-Euler approach. Then, based on active disturbance rejection control (ADRC), the fault tolerant controller is proposed to recover faulty system and reject perturbations. The developed controller takes wind gusts, actuator faults and measurement noises as total perturbations which are estimated by improved extended state observer (ESO) and compensated by nonlinear feedback control law. So, the developed robust fault tolerant controller can successfully accomplish the tracking of the desired output values. Finally, some simulation studies are given to illustrate the effectiveness of fault recovery of the proposed scheme and also its ability to attenuate external disturbances that are introduced from environmental causes such as wind gusts and measurement noises.      

基于非线性干扰观测器的飞机全电刹车系统滑模控制设计

飞机防滑刹车具有典型的强非线性、强耦合和参数时变等特点, 并且跑道环境的干扰容易对飞机的地面滑跑性能造成不利影响. 本文提出了一种基于非线性干扰观测器的飞机全电防滑刹车系统滑模控制设计方法. 首先, 考虑了实际刹车不确定性干扰条件下的防滑刹车动力学建模问题, 通过对高阶非线性刹车系统进行反馈线性化处理, 简化了基于严格反馈的模型. 其次, 基于对主轮打滑原因的深入分析, 设计了非线性干扰观测器对干扰进行在线估计, 并在控制律设计中引入补偿部分. 通过构造递归结构的快速终端滑模控制器来跟踪实时变化的最佳滑移率并建立稳定性条件, 实现了飞机全电防滑刹车系统的有限时间快速稳定并有效抑制了主轮锁定打滑. 通过在不同跑道状态下进行模拟仿真, 验证了本文提出的飞机防滑刹车控制策略可以有效地提高刹车效率.     

Robust multi-mode flight control design for an unmanned helicopter based on multi-loop structure

In this paper, a novel multi-mode flight control strategy for unmanned helicopter, in presence of model uncertainty, atmospheric disturbances and handling qualities specification requirements (as in ADS-33E), based on multi-loop control structure combining robust H-infinity and PI control is presented. In inner loop H-infinity optimal control technique is utilized ensuring the stability of flight control system in case of change of helicopter dynamics, model uncertainties and eliminates effect of gust disturbance on helicopter states and collective/cyclic inputs. PI control in outer loop is used to improve the dynamic and static operation characteristics. Attitude control and attitude holding flight mode with satisfactory command response and decoupling characteristics is designed using the proposed control strategy. Analysis and simulation results show that Level 1 handling requirements as defined in ADS-33E are accomplished even when helicopter is under constant wind circumstance.     

Nonlinear platoon control of Arduino cars with range-limited sensors

This paper investigates the problem of platoon control with sensor range limitation. A nonlinear vehicular platoon model is established, in which the sensing range constraint described by a piecewise nonlinear function is involved. Then a robust nonlinear control design method is proposed based on a disturbance observer and the backstepping technique. The results are obtained in the context of both individual vehicle stability and platoon string stability analysis, which can lead to substantially enhanced platoon control performance with a guaranteed level of attenuation of the disturbance caused by lead vehicle acceleration and wind gust. The effectiveness of the method has been shown by numerical simulations and experiments carried out with Arduino cars.