Fighter aircraft lateral directional axes full envelope control law design

A decoupled wide envelope lateral/directional axes control design is presented for a supermanoeuvrable version of an F-18 aircraft. A control structure is developed that separates gain scheduling issues from aircraft performance issues. Flight condition dependent state and control effectiveness variations are accounted for by an inner loop controller designed using eigenstructure assignment. Structured singular value synthesis is used to design an implicit model following outer loop controller that addresses flying qualities performance specifications. A control selector is designed that generates lateral/directional aerodynamic and thrust vectoring commands from generalized control inputs of roll and yaw acceleration. Flying qualities and robustness analyses show that the control system performs well despite neglected dynamics and system uncertainties. Nonlinear simulations are presented showing excellent decoupling of roll and yaw responses.     

结冰飞机的包线保护与控制裕度研究

飞机结冰具有不确定性和随机性,会破坏飞机的动力学特性,威胁飞行安全.针对这一问题,对结冰飞机的安全边界保护和控制裕度计算展开探究.首先,应用可达集方法,将结冰的作用看作不确定性对抗输入,分析结冰对飞机安全包线边界的影响;然后,基于已知的结冰飞机飞行安全包线,提出两种包线边界保护方法,第1种是改进的最优控制边界保护方法,通过引入新型的最优控制保护动作的切换策略消除传统最优控制保护方法的控制量抖振现象,第2种是保留驾驶员操作权限的安全边界保护方法,通过计算安全边界上的可用控制指引驾驶员完成正确的操作,使得飞机飞行状态不超出安全包线;最后,通过实时计算飞机当前状态点的控制裕度对飞机超出包线进行提前预防,指引驾驶员完成安全程度较高的操作,并提出一种新型的控制裕度迭代计算策略,能够有效降低控制裕度计算的保守性.     

A QFT SUBSONIC ENVELOPE FLIGHT CONTROL SYSTEM DESIGN

An aircraft's response to control inputs varies widely throughout its full flight envelope. Furthermore, the aircraft configuration impacts control response through variations in centre of gravity and moments of inertia. Quantitative feedback theory (QFT) is a robust control system design method which provides a full-envelope flight control system design and gives the engineer direct control over compensator order and gain. A full subsonic flight envelope FCS is designed for using QFT for four representative aircraft configurations. Flying qualities are embedded in the longitudinal design by using a control variable which varies with the aircraft's energy state throughout the flight envelope. Linear simulations with realistically large control inputs are used to validate the design. © 1997 by John Wiley & Sons, Ltd. This paper was prepared under the auspices of the US Government and it is therefore not subject to copyright in the US.     

A novel trajectory planning strategy for aircraft emergency landing using Gauss pseudospectral method

To improve the survivability during an emergency situation, an algorithm for aircraft forced landing trajectory planning is proposed. The method integrates damaged aircraft modelling and trajectory planning into an optimal control framework, in order to deal with the complex aircraft flight dynamics, a solving strategy based on Gauss pseudospetral method （GPM） is presented. A 3-DOF nonlinear mass-point model taking into account the wind is developed to approximate the aircraft flight dynamics after loss of thrust. The solution minimizes the forced landing duration, with respect to the constraints that translate the changed dynamics, flight envelope limitation and operational safety requirements. The GPM is used to convert the trajectory planning problem to a nonlinear programming problem （NLP）, which is solved by sequential quadratic programming algorithm. Simulation results show that the proposed algorithm can generate the minimum-time forced landing trajectory in event of engine-out with high efficiency and precision.     

Multiobjective optimization–based fault‐tolerant flight control system design

The loss of measurements used for controller scheduling or envelope protection in modern flight control systems due to sensor failures leads to a challenging fault‐tolerant control law design problem. In this article, an approach to design such a robust fault‐tolerant control system, including full envelope protections using multiobjective optimization techniques, is proposed. The generic controller design and controller verification problems are derived and solved using novel multiobjective hybrid genetic optimization algorithms. These algorithms combine the multiobjective genetic search strategy with local, single‐objective optimization to improve convergence speed. The proposed strategies are applied to the design of a fault‐tolerant flight control system for a modern civil aircraft. The results of an industrial controller verification and validation campaign using an industrial benchmark simulator are reported.     

推力矢量飞行器的自抗扰控制设计及控制分配

推力矢量飞行器往往需要在大功角等具有大不确定性和强非线性的区域高质量地完成飞行动作,因此,如何应对大范围不确定性是推力矢量飞行器控制设计的关键问题.另一方面,推力矢量飞行器包含多种控制输入并且不同控制输入具有不同物理特性.因此,控制输入分配也是推力矢量飞行器控制设计的关键问题.为了对付大范围的不确定性,本文引入虚拟控制量的概念,采用自抗扰控制技术实现对飞行过程中的总扰动的实时估计和补偿.进一步,考虑控制输入的物理约束条件,提出了保证虚拟控制量达到设计值并使得发动机能耗最小的控制输入分配方案.通过建立对应的优化问题,严格分析其最优解的性质并提出了有限步求解最优控制分配输入量的算法.在仿真环境下,提出的控制算法有效实现了推力矢量飞行器大功角区域的机动动作,并能应对大范围的气动参数不确定性.     

基于MTRDL的自动飞行系统模式需求建模与验证方法[1]

在民机自动飞行过程中,自动飞行系统模式转换是影响安全的重要因素,随着现代民机机载系统的功能与复杂度的快速增长,在需求阶段对自动飞行系统模式转换的安全性分析和验证成为重要的挑战.飞行模式转换的复杂性不仅体现在自动飞行过程中必需的多重飞行模式之间的交互关系,还体现在模式转换与外部环境之间复杂的数据与控制交联关系,这些交联关系同时隐含了飞行模式转换的安全性质,这些特征提高了形式化方法的应用难度.本文工作提出一种领域特定的建模验证框架:首先,提出面向自动飞行系统模式转换的领域需求建模语言MTRDL,和基于该语言扩展于SysML上的建模方法;其次,提出基于安全需求模板的安全性质辅助规约方法;最后,通过对某机型的若干条目化需求的实例研究,证明了本文方法在自动飞行系统模式转换需求验证中的有效性.     

Adaptive flight control using optimal linear regulator techniques

Simple mechanical linkages are often unable to cope with the many control problems associated with high performance aircraft maneuvering over a wide flight envelope. One procedure for retaining uniform handling qualities over such an envelope is to implement a digital adaptive controller. Towards such an implementation an explicit adaptive controller, which makes direct use of online parameter identification, has been developed using linear analysis, and has been evaluated using both the linear and nonlinear equations of motion for a typical fighter aircraft. The system is composed of an online weighted least squares parameter identifier, a Kalman state filter, and a model following control law designed using optimal linear regulator theory. Simulation experiments with realistic measurement noise indicate that the proposed adaptive system has the potential for on-board implementation.     

Nonlinear robustness analysis of flight control laws for highly augmented aircraft

In this paper, a novel hybrid optimisation algorithm is applied to the problem of analysing the robustness of a nonlinear flight control law in the presence of multiple variations in key aircraft parameters over continuous regions of the flight envelope. The analysis employs a typical nonlinear clearance criterion used by the European aerospace industry together with a simulation model of a high performance aircraft with a full authority control law which is gain scheduled over the flight envelope. The hybrid algorithm incorporates global (differential evolution) and local (sequential quadratic programming) optimisation algorithms to improve convergence properties and reduce computational overheads. The proposed approach is shown to have the potential to significantly improve both the reliability and efficiency of the industrial flight clearance process.     

飞机俯仰运动自抗扰控制器设计

提出了利用自抗扰控制器在大包线范围内设计飞机俯仰运动控制器的新方法．利用二阶自抗扰控制器补偿系统模型扰动和外扰，实现了纵向运动俯仰角变量的跟踪控制．自抗扰控制器直接依据飞机的非线性模型，符合飞机动力学模型摄动大的特点，在很大的包线范围内不需要改变控制器的结构和参数，简化了飞行控制律的设计过程．大包线范围内的仿真结果表明，系统具有良好的动态和稳态性能，控制器具有很强的鲁棒性，为解决大包线范围内的飞行控制问题提供了一种有效的新途径．     

持续载荷飞行模拟器控制方程参数优化研究

为提高持续载荷飞行模拟器仿真逼真度,解决持续载荷飞行模拟器角运动本体感知与视觉感知错配问题,对持续载荷飞行模拟器控制方程参数优化问题进行了深入研究。介绍了持续载荷飞行模拟器仿真原理,构建了持续载荷飞行模拟器控制方程。基于人体感知模型设计了的持续载荷飞行模拟器控制方程参数优化算法,给出了控制方程参数优化的具体流程。通过仿真实例验证了所提出控制方程参数优化算法的可行性和有效性。研究结果可为持续载荷飞行模拟器控制算法设计提供参考。     

Maximizing the number of conflict-free aircraft using mixed-integer nonlinear programming

We address the conflict detection and resolution problem in air traffic control, where an aircraft conflict is a loss of separation between aircraft trajectories. Conflict avoidance is crucial to ensure flight safety and remains a challenging traffic control problem. We focus on speed control to separate aircraft and consider two approaches: (i) maximize the number of conflicts resolved and (ii) identify the largest set of conflict-free aircraft. Both problems are modeled using mixed-integer nonlinear programming and a tailored greedy algorithm is proposed for the latter. Computational efficiency is improved through a pre-processing algorithm which attempts to reduce the size of the conflict resolution models by detecting the existence of pairwise potential conflicts. Numerical results are provided after implementing the proposed models and algorithms on benchmark conflict resolution instances. The results highlight the benefits of using the proposed pre-processing step as well as the versatility and the efficiency of the proposed models.     

改进变步长算法在实时飞行仿真中的应用

飞行模拟机是民航训练飞行员的重要装备,飞行仿真系统是飞行模拟机的重要系统之一.飞行仿真要建立飞机的全量运动方程,利用数值算法解算运动方程达到仿真飞机飞行状况的目的.采用四元数法表示的飞机欧拉方程能够克服普通欧拉方程奇异性,但用定步长方法解算会产生较大累积误差,所以必须采用变步长方法.实时飞行仿真要求较高的实时性与逼真度,通过仿真试验分析,确定了采用一种改进变步长2阶Runge-Kutta法,该方法具有迭代次数少,解算精度高,实时性强的优点.利用该改进变步长算法,编写了实时飞行系统仿真软件,软件中使用相应算法解决了变步长算法选择步长与系统迭代定时时间不匹配的矛盾,实现了精确的实时仿真.     

面向失控改出训练的模型预测洗出算法设计

近年来飞机失控已成为飞行事故主要原因,飞行模拟器需要具备失控预防和改出训练功能,因此对洗出算法提出了更高的要求。利用模型预测控制理论对约束处理的优势,结合人体前庭感知模型,建立了基于模型预测控制的洗出算法,采用失速改出这一典型飞机失控情况进行仿真实验,并与经典洗出算法进行了比较,结果表明,模型预测控制洗出算法在约束范围内,提高了仿真逼真度,并具有较好的调整灵活性,对飞行模拟器失控改出训练具有一定应用价值。     

垂直起降飞机的全局轨迹跟踪控制

研究垂直起降飞机在任意输入耦合作用下的轨迹跟踪控制问题．垂直起降飞机是具有3个自由度、2个控制输入的欠驱动系统．首先通过控制输入和坐标变换,使飞机的动力学方程变换成严格反馈形式;然后基于后推法的思想推导出保证系统渐近收敛于参考轨迹的时变反馈控制规律．该方法将系统分解为低阶子系统来处理,利用中间虚拟控制变量和部分Lyapunov函数筒化了控制器的设计．仿真结果表明所设计的控制器是有效的．     

Flight control of a rotary wing UAV using backstepping

This paper presents a novel application of backstepping controller for autonomous landing of a rotary wing UAV (RUAV). This application, which holds good for the full flight envelope control, is an extension of a backstepping algorithm for general rigid body velocity control. The nonlinear RUAV model used in this paper includes the flapping and servo dynamics. The backstepping‐based controller takes advantage of the ‘decoupling’ of the translation and rotation dynamics of the rigid body, resulting in a two‐step procedure to obtain the RUAV control inputs. The first step is to compute desired thrusts and flapping angles to achieve the commanded position and the second step is to compute control inputs, which achieve the desired thrusts and flapping angles. This paper presents a detailed analysis of the inclusion of a flapping angle correction term in control. The performance of the proposed algorithm is tested using a high‐fidelity RUAV simulation model. The RUAV simulation model is based on miniature rotorcraft parameters. The closed‐loop response of the rotorcraft indicates that the desired position is achieved after a short transient. The Eagle RUAV control inputs, obtained using high‐fidelity simulation results, clearly demonstrate that this algorithm can be implemented on practical RUAVs. Copyright © 2009 John Wiley & Sons, Ltd.     

Autonomous feature following for visual surveillance using a small unmanned aerial vehicle with gimbaled camera system

This paper represents the development of feature following control and distributed navigation algorithms for visual surveillance using a small unmanned aerial vehicle equipped with a low-cost imaging sensor unit. An efficient map-based feature generation and following control algorithm is developed to make an onboard imaging sensor to track a target. An efficient navigation system is also designed for real-time position and velocity estimates of the unmanned aircraft, which is used as inputs for the path following controller. The performance of the proposed autonomous path following capability with a stabilized gimbaled camera onboard a small unmanned aerial robot is demonstrated through flight tests with application to target tracking for real-time visual surveillance.     

Modeling and correction of multipath interference in time of flight cameras

Multipath interference of light is the cause of important errors in Time of Flight (ToF) depth estimation. This paper proposes an algorithm that removes multipath distortion from a single depth map obtained by a ToF camera. Our approach does not require information about the scene, apart from ToF measurements. The method is based on fitting ToF measurements with a radiometric model. Model inputs are depth values free from multipath interference whereas model outputs consist of synthesized ToF measurements. We propose an iterative optimization algorithm that obtains model parameters that best reproduce ToF measurements, recovering the depth of the scene without distortion. We show results with both synthetic and real scenes captured by commercial ToF sensors. In all cases, our algorithm accurately corrects the multipath distortion, obtaining depth maps that are very close to ground truth data.     

存在整数约束的分布式驱动变体飞行器控制分配

针对一类含有整数控制约束的分布式驱动变体飞行器在线控制分配问题,提出了一种基于布谷鸟搜索算法的求解策略.首先,考虑到指令分配误差以及作动器的损耗,将飞行器在线作动器控制分配问题表示为一类整数规划问题.然后,设计改进的布谷鸟搜索算法求解作动器的控制指令,采用Tent混沌映射初始化种群、自适应的步长控制量等措施提高算法的搜索效率.最后,将提出的控制分配方法应用于一类新型操纵面飞行器,仿真结果验证了该方法的有效性.     

Design and evaluation of a model predictive vehicle control algorithm for automated driving using a vehicle traffic simulator

This paper describes the design and evaluation of a model predictive control algorithm for automated driving on a motorway using a vehicle traffic simulator. For the development of a highly automated driving control algorithm, motion planning is necessary to satisfy driving condition in various road traffic situations. There are two key issues in motion planning of automated driving vehicles. One of the key issues is how to handle potentially dangerous situations that could occur in order to guarantee the safety of vehicles. The second key issue is how to guarantee the disturbance rejection of the controller under model uncertainties and external disturbances. To improve safety with respect to the future behaviors of subject vehicles, not the current states but rather the predicted behaviors of surrounding vehicles should be considered. The desired driving mode and a safe driving envelope are determined based on the probabilistic prediction of surrounding vehicles behaviors over a finite prediction horizon. To obtain the desired steering angle and longitudinal acceleration for maintaining the subject vehicle in the safe driving envelope during a finite prediction horizon, a motion planning controller is designed based on an model predictive control (MPC) approach. The developed control algorithm has been successfully implemented on a vehicle electronic control unit (ECU). The proposed control algorithm has been evaluated on a real-time vehicle traffic simulator. The throttle, brake, and steering control inputs and the controlled vehicle behavior have been compared to those of manual driving.