High-torque density integrated electro-mechanical flight actuators

Electro-mechanical flight actuators (EMFAs) are core flight-critical vehicle components. Fly-by-wire or fly-by-light control of EMFAs is performed by flight management systems (flight, mission, propulsion, and integrated controls that manage any combination of specific flight, mission, and propulsion functions). Reported here are novel results in the analysis of EMFAs with permanent-magnet synchronous motors, with particular interest in the application of brushless high-torque density motors which have superior characteristics compared with other state-of-the-art motor technologies. It is shown that due to nonlinearities and bounds, new control algorithms must be developed and implemented to achieve a spectrum of performance and requirements for EMFAs. A number of important issues in control, analysis, model development, integration, and verification are studied. Tracking control algorithms are synthesized, stability studied, and novel analysis results are reported. Advanced computer-aided engineering software tools and emerging simulation-based design environments are used to guarantee high fidelity modeling and analysis within data intensive simulation. Proof-of-concept demonstration testbeds for the design of advanced EMFAs and their components are developed, and EMFA imitator performance thoroughly studied. Verification of the concepts reported are formed and documented. Precise tracking, disturbance attenuation, accuracy, stability, robustness, and excellent acceleration capabilities are reported. A demonstration is performed to substantiate the theoretical analyses to add credence to its applicability as an approach and method that the designer of future EMFAs can use to design a new class of actuators for aircraft flight control surfaces     

Fractional order modeling and control of dissimilar redundant actuating system used in large passenger aircraft

In this paper, a methodology has been developed to address the issue of force fighting and to achieve precise position tracking of control surface driven by two dissimilar actuators. The nonlinear dynamics of both actuators are first approximated as fractional order models. Based on the identified models, three fractional order controllers are proposed for the whole system. Two Fractional Order PID (FOPID) controllers are dedicated to improving transient response and are designed in a position feedback configuration. In order to synchronize the actuator dynamics, a third fractional order PI controller is designed, which feeds the force compensation signal in position feedback loop of both actuators. Nelder-Mead (N-M) optimization technique is employed in order to optimally tune controller parameters based on the proposed performance criteria. To test the proposed controllers according to real flight condition, an external disturbance of higher amplitude that acts as airload is applied directly on the control surface. In addition, a disturbance signal function of system states is applied to check the robustness of proposed controller. Simulation results on nonlinear system model validated the performance of the proposed scheme as compared to optimal PID and high gain PID controllers.     

The All-Electric Fighter Airplane Flight Control Issues, Capabilities, and Projections

The prime issues raised in any all-electric airplane discussion are (1) is the electric power system as reliable and trustworthy as a hydraulic power system; (2) can electromechanical flight control actuators perform satisfactorily, i.e., can the performance match that of hydraulic actuators; (3) can redundant electromechanical actuation systems (EMAS) be designed to equal the flight safety reliability of dual tandem hydraulic actuators; and (4) can satisfactory solutions be found or developed for dissipating the heat generated in actuators and power controllers. The first question should be inconsequential since it is assumed that the all-electric aircraft will be equipped with a fly-by-wire (FBW) flight control system (FCS) which is already dependent upon an uninterrupted supply of electrical power. Design studies and hardware already developed show that the answer to question (2) is that EMAS outperform hydraulic actuators, particularly under load. The answer to question (3) is not as clear primarily because the issue has not been addressed in any depth. As posed the answer must be yes, but with the proviso that the weight might be greater than currently predicted. Studies have shown that we can cope with the heat dissipation issue addressed in question (4) in the case of motors and inverter/power controllers. The projections regarding usage of EMAS and the future of the all-electric airplane must be based on the type of vehicle (small subsonic transport, large transport, or military tighter) and the economics involved.     

Reconfigurable flight control via multiple model adaptive controlmethods

An aircraft flight control system with reconfigurable capabilities is considered. A multiple model adaptive controller (MMAC) is shown to provide effective reconfigurability when subjected to single and double failures of sensors and/or actuators. A command generator tracker/proportional-plus-integral/Kalman filter (CGT/PI/KF) form of controller was chosen for each of the elemental controllers within the MMAC algorithm and each was designed via LQG synthesis to provide desirable vehicle behavior for a particular failure status of sensors and actuators. The MMAC performance is enhanced by an alternate computation of the MMAC hypothesis probabilities, use of maximum a posteriori probability (MAP) versus Bayesian form of the MAC (or a modified combination of both), and reduction of identification ambiguities through scalar residual monitoring for the case of sensor failures     

某型无人直升机前飞段仿真建模与试飞验证

针对某型无人直升机无铰式旋翼技术验证和飞行试验需求,建立了能够用于实时仿真的非线性飞行动力学模型,并基于经典PID控制算法完成了飞行控制律设计。为验证理论模型准确性和控制参数合理性,相继开展了盘旋飞行和大速度飞行的半物理仿真和飞行试验,并基于飞行试验控制效果评估完成了部分控制参数的优化设计。数据分析表明:半物理仿真和飞行试验的时域响应和配平特性均吻合较好,验证了非线性飞行动力学模型的准确性;飞行试验中无人直升机姿态和速度响应均能够较好地跟踪其设定值,所设计的飞行控制参数能够满足某型无人直升机稳态飞行控制要求。     

Disturbance observer-based backstepping control for hypersonic flight vehicles without use of measured flight path angle

In this paper a nonlinear control method is proposed for the tracking control of hypersonic flight vehicles. The designed control laws do not utilize the measured flight path angle due to its inferior accuracy in practical engineering. For this, an estimated flight path angle is designed via the measurements of the altitude and velocity. A tracking differentiator is designed for constructing nonlinear disturbance observer which is used to estimate the model uncertainties including the parameter indeterminacies and external disturbances in the channels of velocity and pitch rate. A robust high-order differentiator is introduced to avoid the employment of the measured flight path angle and estimate the lumped disturbance in dynamics of flight path angle. Meanwhile, the possible saturation of the control inputs is considered and compensated by the auxiliary states. The boundness of closed-loop signals is proved through the Lyapunov theory. Comparative simulations are carried out and the results demonstrate the effectiveness of the proposed method.     

Fuzzy robust nonlinear control approach for electro-hydraulic flight motion simulator

A fuzzy robust nonlinear controller for hydraulic rotary actuators in flight motion simulators is proposed. Compared with other three-order models of hydraulic rotary actuators, the proposed controller based on first-order nonlinear model is more easily applied in practice, whose control law is relatively simple. It not only does not need high-order derivative of desired command,but also does not require the feedback signals of velocity, acceleration and jerk of hydraulic rotary actuators. Another advantage is that it does not rely on any information of friction, inertia force and external disturbing force/torque, which are always difficult to resolve in flight motion simulators. Due to the special composite vane seals of rectangular cross-section and goalpost shape used in hydraulic rotary actuators, the leakage model is more complicated than that of traditional linear hydraulic cylinders. Adaptive multi-input single-output(MISO) fuzzy compensators are introduced to estimate nonlinear uncertain functions about leakage and bulk modulus. Meanwhile, the decomposition of the uncertainties is used to reduce the total number of fuzzy rules. Different from other adaptive fuzzy compensators, a discontinuous projection mapping is employed to guarantee the estimation process to be bounded. Furthermore, with a sufficient number of fuzzy rules, the controller theoretically can guarantee asymptotic tracking performance in the presence of the above uncertainties, which is very important for high-accuracy tracking control of flight motion simulators.Comparative experimental results demonstrate the effectiveness of the proposed algorithm, which can guarantee transient performance and better final accurate tracking in the presence of uncertain nonlinearities and parametric uncertainties.     

飞行器神经元控制系统的研究与设计

提出了一种基于神经元网络的飞行控制系统设计方法 ,该方法设计的神经元飞行控制器具有良好的鲁棒性 ,使飞行器在整个飞行包络内都能保持某种最优的操纵品质。给出的计算机仿真结果显示出神经元网络作为飞行控制器在处理飞行器参数大范围变化的非线性特性方面具有潜在的优良品质     

Algorithms for adaptive control of two-arm flexible manipulatorsunder uncertainty

The author uses a nonlinear extension of model reference adaptive control (MRAC) technique to guide a double-arm nonlinearizable robot manipulator with flexible links, driven by actuators collocated with joints subject to uncertain payload and inertia. The objective is to track a given simple nonlinear, rigid but compatible dynamical model in real, possibly stipulated time and within stipulated degree of accuracy of convergence, while avoiding collision of the arms. The objective is attained by a specified signal adaptive feedback controller and by adaptive laws. Both are given in closed form. A case of a two-degree-of-freedom (DOF) manipulator illustrates the technique     

基于SVM辨识的涡扇发动机全包线稳态控制方法

针对涡扇发动机全飞行包线范围稳态最优控制器的设计问题,首先根据不同飞行条件下发动机各工作状态的稳态“小偏差”线性模型,采用线性二次型调节器(LQR)分别设计得到相应的发动机最优线性控制器参数,然后将所得到的线性控制器用支持向量机方法进行非线性逼近,得到控制器参数的支持向量机辨识模型,以满足发动机全包线、全状态稳态控制的需要.支持向量机模型的输入为飞行高度、马赫数和稳态转速,输出为线性控制器参数.应用实例表明:该方法在全包线范围内对发动机最优稳态控制器的逼近误差均在2%以内,能较好满足控制精度要求.      

飞行/推进系统分散控制优化设计及鲁棒性分析

以一种短距起降战斗机的飞行/推进综合控制系统设计为背景,对分散控制如何保持集中控制的性能和鲁棒性的问题提出利用优化的思想设计分散控制器.首先采用遗传算法设计集中控制器,作为分散控制的性能参考,然后给出具有接口变量的分散控制器设计方法,通过分析得出影响分散控制性能的关键因素,并通过数学推导得到以频率加权矩阵为设计参数的分散控制性能表达式,将分散控制器设计转化为优化问题,采用遗传算法求解得到分散控制器.分散控制器设计中同时用到了一种改进的平衡降阶方法.通过仿真和结构奇异值分析验证了这种优化设计方法可使分散控制达到集中式控制的性能和鲁棒性.      

Proportional fuzzy feed-forward architecture control validation by wind tunnel tests of a morphing wing

In aircraft wing design, engineers aim to provide the best possible aerodynamic performance under cruise flight conditions in terms of lift-to-drag ratio. Conventional control sur-faces such as flaps, ailerons, variable wing sweep and spoilers are used to trim the aircraft for other flight conditions. The appearance of the morphing wing concept launched a new challenge in the area of overall wing and aircraft performance improvement during different flight segments by locally altering the flow over the aircraft's wings. This paper describes the development and appli-cation of a control system for an actuation mechanism integrated in a new morphing wing structure. The controlled actuation system includes four similar miniature electromechanical actuators dis-posed in two parallel actuation lines. The experimental model of the morphing wing is based on a full-scale portion of an aircraft wing, which is equipped with an aileron. The upper surface of the wing is a flexible one, being closed to the wing tip; the flexible skin is made of light composite materials. The four actuators are controlled in unison to change the flexible upper surface to improve the flow quality on the upper surface by delaying or advancing the transition point from laminar to turbulent regime. The actuators transform the torque into vertical forces. Their bases are fixed on the wing ribs and their top link arms are attached to supporting plates fixed onto the flex-ible skin with screws. The actuators push or pull the flexible skin using the necessary torque until the desired vertical displacement of each actuator is achieved. The four vertical displacements of the actuators, correlated with the new shape of the wing, are provided by a database obtained through a preliminary aerodynamic optimization for specific flight conditions. The control system is designed to control the positions of the actuators in real time in order to obtain and to maintain the desired shape of the wing for a specified flight condition. The feasibility and effectiveness of the developed control system by use of a proportional fuzzy feed-forward methodology are demon-strated experimentally through bench and wind tunnel tests of the morphing wing model.     

先进战斗机过失速机动模型飞行试验技术

具有过失速机动能力的战斗机在近距空战中能够取得快速占位、先敌瞄准、有效规避攻击的战术优势,是先进战斗机的标志性性能要求。模型飞行试验技术作为空气动力学研究三大手段之一,在解决飞行器技术难题、实现技术创新方面发挥了重要作用。本文介绍了中国空气动力研究与发展中心利用带动力自主控制模型飞行试验平台发展的过失速机动模型飞行试验技术,以及开展的先进战斗机构型典型过失速机动模型飞行试验,分述了在大迎角非定常气动建模、宽量程气流系参数测量、大迎角非线性控制、推力矢量控制、大迎角非定常气动参数辨识方面的研究工作与解决这些关键问题的技术途径。通过此项研究,在国内首次实现了先进战斗机构型缩比模型典型过失速机动飞行,相关研究成果可为先进战斗机实现过失速机动飞行能力提供有力的技术支撑。     

Friction compensation for low velocity control of hydraulic flight motion simulator: A simple adaptive robust approach

Low-velocity tracking capability is a key performance of flight motion simulator (FMS), which is mainly affected by the nonlinear friction force. Though many compensation schemes with ad hoc friction models have been proposed, this paper deals with low-velocity control without friction model, since it is easy to be implemented in practice. Firstly, a nonlinear model of the FMS middle frame, which is driven by a hydraulic rotary actuator, is built. Noting that in the low velocity region, the unmodeled friction force is mainly characterized by a changing-slowly part, thus a simple adaptive law can be employed to learn this changing-slowly part and compensate it. To guarantee the boundedness of adaptation process, a discontinuous projection is utilized and then a robust scheme is proposed. The controller achieves a prescribed output tracking transient performance and final tracking accuracy in general while obtaining asymptotic output tracking in the absence of modeling errors. In addition, a saturated projection adaptive scheme is proposed to improve the globally learning capability when the velocity becomes large, which might make the previous proposed projection-based adaptive law be unstable. Theoretical and extensive experimental results are obtained to verify the high-performance nature of the proposed adaptive robust control strategy.     

抑制飞控系统舵机间隙影响的非线性补偿器设计

通过对舵机间隙非线性特性的分析和极限环的定义及产生条件的讨论,在飞控系统中采用非线性补偿的方法,设计了间隙补偿器,并介绍了其工程实现方法,进行了相应的数字仿真和半物理仿真试验以及试验结果的对比分析。结果表明,此方法有效地解决了飞控系统由于舵机间隙引起的超调与极限环振荡现象,使飞控系统对舵机的频率特性以及间隙各方面要求大大降低,其工程实现方法简单实用、普遍性较强,具有较高的工程应用价值。     

利用神经网络设计航空发动机全包线最优控制器

本文提出一种用神经网络拟合飞行条件、发动机工况与发动机最优控制器参数之间关系, 从而设计适合于全飞行包线范围内发动机最优稳态控制器的方案。该方案可以针对发动机分段线性化模型, 利用成熟的线性控制设计方法设计非线性控制器, 且控制器结构简单、实时性好。仿真结果表明, 所设计的发动机控制系统在整个飞行包线内的设计点及非设计点均具有良好的性能。      

无人机空中加油自主会合的制导与控制

针对无人机空中加油的自主会合问题,进行了相应制导律和非线性控制器的设计。通过改进的带角度约束的三维比例制导律实现对航向角的控制,以协调转弯的方式将航迹角指令转化为姿态角指令。基于无人机六自由度的动力学模型,针对无人机的姿态控制,采用时标分离的方法设计了慢子系统和快子系统,并对这两个子系统分别进行动态逆控制设计。同时,基于滑模控制的方法设计了满足自主会合要求的速度控制律。在保证无人机飞行稳定的基础上,实现了对控制和制导指令的精确跟踪。仿真结果表明,所设计的制导律和控制律能够实现无人机空中加油的自主会合,具有良好的动态特性。     

基于多模型方法的全包络鲁棒飞行控制器设计

利用新一代歼击机不同平衡点的多个非线性子模型对其机动飞行的全包络模型进行逼近。对于每一个子模型,设计相应的动态逆控制器,应用模糊神经网络产生控制器切换决策,实现不同飞行状态下不同模型控制器之间的相互切换。同时为了提高多模型飞行控制效果,对各模型控制器的输入及输出采样并作为神经网络的学习样本,形成一个全包络内的多模型统一神经网络控制器。最后通过歼击机的大迎角机动仿真来验证所设计的基于多模型的统一神经网络控制器的有效性,仿真结果表明所设计的统一神经网络控制器是有效的。     

Effective control allocation using hierarchical multi-objective optimization for multi-phase flight

For different flight phases in an overall flight mission, different control and allocation preferences should be pursued considering lift, drag or maneuverability characteristics. The multi-objective flight control allocation problem for a multi-phase flight mission is studied. For an overall flight mission, different flight phases namely climbing, cruise, maneuver and gliding phases are defined. Firstly, a multi-objective control allocation problem considering drag, lift or control energy preference is constructed. Secondly, considering different control preferences at different flight phases, the analytic hierarchical process method is used to construct a comprehensive performance index from different objectives such as lift or drag preferences. The active set based dynamic programming optimization method is used to solve the real-time optimization problem. For the validation, the Innovative Control Effector (ICE) tailless aircraft nonlinear model and the angular acceleration measurements based adaptive Incremental Backstepping (IBKS) are used to construct the validation platform. Finally, an overall flight mission is simulated to demonstrate the efficiency of the proposed multi-phase and multi-objective flight control allocation method. The results show that the comprehensive performance index for different phases, which are determined from the Analytic Hierarchy Process (AHP) method, can suitably satisfy the preference requirements for different flight phases.     

直升机飞行动力学逆问题研究综述

直升飞机动力学逆问题是已知运动的控制规律,对直升机机动飞行和现代飞行控制律设计有重要意义。根据直升机飞行动力学逆问题研究的现状,概述现代飞行动力学逆问题的研究内容及进展,重点分析直升机逆仿真技术的特点,讨论直升机最佳机动控制与非线性控制律设计的途径与方法,展示直升机逆问题研究的前景以及存在的问题,供直升机设计和飞行动力学研究人员参考。