Compound Control for Hydraulic Flight Motion Simulator

The design of a compound control is presented for the servo system of hydraulic flight motion simulator, which suffers from highly nonlinear dynamics, large parameter time-variation and severe load coupling among channels. The compound control is composed of a robust feedback controller and a feedforward compensator. The design aim is to achieve high tracking performance even in the presence of considerable uncertainty, external disturbance and load coupling among channels. Toward this aim the feedback controller for rejecting perturbation and disturbance is designed by using μ synthesis optimization technique and the feedforward compensator for compensating time lag of dynamic system is established based on the basic idea of zero phase error tracking. To validate the proposed control strategy, simulations and experiments are implemented, and show that the resulting system is highly robust against model perturbation and possesses excellent capability of suppressing the load coupling and improving the tracking performance.     

无人机机动轨迹跟踪系统设计

对无人机机动飞行轨迹跟踪系统的内环姿态控制律和外环轨迹跟踪控制律两部分分别进行了设计。利用非线性动态逆方法设计了内环姿态控制律。外环轨迹跟踪控制律采用逆动力学前馈加模糊反馈的控制结构,提高系统对飞行条件及期望轨迹剧烈变化时的跟踪精度。仿真结果表明,所设计的系统能够控制无人机精确跟踪指定的机动轨迹,且相对于固定增益系统具有更好的鲁棒性。     

轨迹跟踪伺服系统的鲁棒复合控制

针对控制输入饱和受限且带有未知扰动的电机伺服系统,提出一种实现曲线轨迹准确跟踪的鲁棒复合控制方案。该方案引入一个参考信号生成器和一个扩展状态观测器,其中参考信号生成器可根据目标轨迹信号构造出对应的状态量,扩展状态观测器用于对系统的状态量和扰动进行估计, 采用反馈与前馈相结合构成最终的控制律。利用Lyapunov理论对闭环系统的稳定性进行了严格分析。在MATLAB中进行了仿真研究,随后在一个DSP控制的永磁直线电机二维伺服平台进行了试验验证。结果表明:所提的控制方案能在轨迹跟踪任务中取得优越的瞬态性能和稳态准确性,而且对目标轨迹和扰动的幅值差异具有较好的鲁棒性。     

基于QFT的鲁棒飞行控制器设计

首先对定量反馈控制理论及其发展进行了介绍,并指出了其所能解决的问题,以及器的一般求解步骤,按着讲述了鲁棒控制中的灵敏度设计方法,讨论了基于ＱＦＴ的鲁棒灵敏度设计思路,最后以某型号飞机为算例,采用ＱＦＴ方法设计了鲁棒控制律,计算和仿真结果说明了定量反馈控制理论是一种设计鲁棒飞行控制律的有效方法。     

Decoupled ultimate boundedness control of systems and largeaircraft maneuver

The robust trajectory control of a class of nonlinear systems which can be decoupled by state-variable feedback is considered. It is assumed that the system matrices are unknown but bounded. A nonlinear control law is derived so that the tracking error in the closed-loop system is uniformly bounded and tends to a certain small neighborhood of the origin. The error dynamics are asymptotically decoupled in an approximate sense. The controller includes a reference trajectory generator and uses the integral feedback of the tracking error. On the basis of this result, a flight control system is designed for the control of roll angle, angle of attack, and sideslip in rapid, nonlinear maneuvers of aircraft. Simulation results are presented to show that large, simultaneous lateral and longitudinal maneuvers can be performed in spite of the uncertainty in the stability derivatives     

高精度液压仿真转台鲁棒控制

 针对液压仿真转台具有时变不确定性、复杂外干扰等特点和高精度控制性能要求，提出了一种鲁棒复合控制结构，该结构由鲁棒内回路补偿器、外回路反馈控制器和输入信号前馈补偿器三部分组成。其中，鲁棒内回路补偿器用来抑制外干扰和时变不确定性的影响，外回路反馈控制器的作用是保证闭环系统的整体性能，输入信号前馈补偿器实现对系统动态时滞的补偿，以保证对参考信号的精确跟踪。以某型液压仿真转台内环为例，首先根据所提出控制策略的基本思想，给出了控制系统的具体设计过程，然后，进行了阶跃响应、低速跟踪和正弦响应试验。试验结果表明，所提出的鲁棒控制策略是有效的和可行的。     

大机动飞机的非线性鲁棒控制律设计

采用非线性不确定系统的高增益控制建设设计方法,为某型大机动飞机在特定飞行条件下设计了鲁棒控制律,以跟踪期望的输出轨迹,并在不同飞行条件下进行了系统仿真研究。仿真结果表明,采用所设计的控制律,在不同飞行条件下,飞机均可同时完成较精确的纵向和侧向机动跟踪,说明控制律具有较好的鲁棒性。     

Robust sliding-mode control for the uncertain MIMO aircraft model F-18

Robust flight control laws based on variable structure control (VSC) theory and Lyapunov V-function method are designed for a simplified aircraft model F-18. A min-max control (MMC) and VSC laws are derived, for multi-input multi-output (MIMO) systems with plant uncertainties and input disturbance. Two types of robust feedback controllers MMC and VSC for uncertain MIMO systems are considered. For both cases the existence conditions of a stable sliding mode and the robust asymptotic stability in uncertain MIMO systems by MMC and VSC are investigated. For the design of an MMC and VSC, measurable states and sliding surface are chosen so that the zero dynamics of the system are stable. An application of tracking and positioning of VSC of longitudinal dynamics is presented. Finally, simulation results are presented to show the effectiveness of the design methods.     

Nonlinear adaptive and sliding mode flight path control of F/A-18 model

The question of inertial trajectory control of aircraft in the three-dimensional space is discussed. It is assumed that the nonlinear aircraft model has uncertain aerodynamic derivatives. The control system is decomposed into a variable structure outer loop and an adaptive inner loop. The outer-loop feedback control system accomplishes (x,y,z) position trajectory and sideslip angle control using the derivative of thrust and three angular velocity components (p,q,r) as virtual control inputs. Then an adaptive inner feedback loop is designed, which produces the desired angular rotations of aircraft using aileron, elevator, and rudder control surfaces to complete the maneuver. Simplification in the inner-loop design is obtained based on a two-time scale (singular perturbation) design approach by ignoring the derivative of the virtual angular velocity vector, which is a function of slow variables. These results are applied to a simplified F/A-18 model. Simulation results are presented which show that in the closed-loop system asymptotic trajectory control is accomplished in spite of uncertainties in the model at different flight conditions.     

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.     

Sensitivity Reduction in Aircraft Control Systems

A method for reducing trajectory sensitivity to parameter perturbations for linear feedback systems is described. Application of the method to the design of aircraft control systems, with special reference to a helicopter forward flight control system, is illustrated. The response of the system based on this method is found to be better than that obtained with fixed-feedback gain controllers, although the response may not be as good as that of an adaptive control scheme. The main advantage of the method is the simplicity of its implementation relative to that of the adaptive control scheme which requires an on-board computer.     

A homogenization-planning-tracking method to solve cooperative autonomous motion control for heterogeneous carrier dispatch systems

Taxiing aircraft and towed aircraft with drawbar are two typical dispatch modes on the flight deck of aircraft carriers. In this paper, a novel hierarchical solution strategy, named as the Homogenization-Planning-Tracking (HPT) method, to solve cooperative autonomous motion control for heterogeneous carrier dispatch systems is developed. In the homogenization layer, any towed aircraft system involved in the sortie task is abstracted into a virtual taxiing aircraft. This layer transforms the heterogeneous systems into a homogeneous configuration. Then in the planning layer, a centralized optimal control problem is formulated for the homogeneous system. Compared with conducting the path planning directly with the original heterogeneous system, the homogenization layer contributes to reduce the dimension and nonlinearity of the formulated optimal control problem in the planning layer and consequently improves the robustness and efficiency of the solution process. Finally, in the tracking layer, a receding horizon controller is developed to track the reference trajectory obtained in the planning layer. To improve the tracking performance, multi-objective optimization techniques are implemented offline in advance to determine optimal weight parameters used in the tracking layer. Simulations demonstrate that smooth and collision-free cooperative trajectory can be generated efficiently in the planning phase. And robust trajectory tracking can be realized in the presence of external disturbances in the tracking phase. The developed HPT method provides a promising solution to the autonomous deck dispatch for unmanned carrier aircraft in the future.     

飞机的全局稳定性分析和非线性控制

现代军用飞机常设计为在大迎角下飞行。此时飞机是一个高度非线性系统，其稳定特性不能用线性方法求解。而实现控制，特别是在非线性不稳定性的情况下，更是十分困难的。本文介绍了一种综合的分析飞机非线性稳定性和控制的方法。即用分岐理论来决定飞机的全局稳定性。用四阶龙格－库塔积分来计算飞机运动的平衡面和分岐点，并构造运动状态的扰动传播矩阵，而此矩阵的特征值可用来预测稳定性的时变性。此外，还利用扰动传播矩阵来求得为满足规定的飞机反应特性（通常由频率和阻尼表示）所需的操纵，即各操纵面反馈回路的放大系数值。对典型飞机的算例计算结果表明，非线性控制是成功的。     

Robust dynamic output feedback control for switched polytopic systems under asynchronous switching

The robust controller design problem for switched polytopic systems under asynchronous switching is addressed.These systems exist in many aviation applications, such as dynamical systems involving rapid variations.A switched polytopic system is established to describe the highly maneuverable technology vehicle within the full flight envelope and a robust dynamic output feedback control method is designed for the switched polytopic system.Combining the Lyapunov-like function method and the average dwell time method, a sufficient condition is derived for the switched polytopic system with asynchronous switching and data dropout to be globally,uniformly and asymptotically stable in terms of linear matrix inequality.The robust dynamic output feedback controller is then applied to the highly maneuverable technology vehicle to illustrate the effectiveness of the proposed approach.The simulation results show that the angle of attack tracking performance is acceptable over the time history and the control surface responses are all satisfying along the full flight trajectory.     

Robust LPV modeling and control of aircraft flying through wind disturbance

This article deals with the disturbance attenuation control of aircraft flying through wind shear via Linear Parameter Varying(LPV) modeling and control method. A Flight Dynamics Model(FDM) with wind shear effects considered was established in wind coordinate system. An LPV FDM was built up based on function substitution whose decomposing function was optimized by Genetic Algorithm(GA). The wind disturbance was explicitly included in the system matrix of LPV FDM. Taking wind disturbance as external uncertainties, robust LPV control method with the LPV FDM was put forward. Based on ride quality and flight safety requirements in wind disturbance, longitudinal and lateral output feedback robust LPV controllers were designed respectively,in which the scheduling flight states in LPV model were actually dependent parameters in LPV control. The results indicate that LPV FDM can reflect the instantaneous dynamics of nonlinear system especially at the boundary of aerodynamic envelope. Furthermore, the LPV FDM also can approach nonlinear FDM's response in wind disturbance special flight. Compared with a parameter-invariant LQR controller designed with a small-disturbance FDM, the LPV controllers show preferable robustness and stability for disturbance attenuation.     

Dynamics,stability, and control of a four-cable mount system for wind tunnel test

A four-cable mount system is proposed for full-model wind tunnel flutter tests, which may adjust the pitch and roll attitude of the aircraft scaled model and ensure that the model is not subjected to cable tension. The system provides sufficient support to simulate the free flight of the aircraft by applying appropriate spring stiffness and cable tensions. The proposed four-cable mount system is modeled based on Lagrange mechanics, and its dynamics equations consider aerodynamic effects. The singularity of the system and its bifurcation characteristics under flow conditions are analysed to determine the supercritical bifurcation phenomenon for different tension levels and distances from the front suspension point to the mass centre of the model. The mathematical expressions of the longitudinal flight stability of the cable mount system are derived by linearising the system dynamics equations using small perturbations. The influence of the cable tension, spring stiffness, suspension point position, and other factors on the flight stability of the aircraft are analysed. A feedforward control algorithm is proposed to minimize the total elastic potential energy of the system. The results show that the model is in the level flight state when the elastic potential energy of the four-cable mount system is minimized. A feedback control design method is proposed based on the Lyapunov stability theory to derive the closed-loop stability conditions. The system dynamics model that includes the aircraft rigid body model, flexible cables, pulleys, springs, aerodynamic model, and servo motor control is established using the flexible multibody dynamics method. A multibody dynamics solver and Simulink are used to simulate the attitude adjustment of the model in the wind tunnel and verify the supercritical bifurcation characteristics of the system and the effectiveness of the feedback and feedforward control.     

特征结构配置在设计直接升力控制律中的应用

采用直接力控制可弥补常规飞机在轨迹操纵方面的不足,并产生某些新的运动模式。文中首先对飞机直接升力控制的3种基本运动模式进行了讨论。归纳出直接升力控制律的设计就是输出解耦控制系统的设计问题。在简述了用特征结构配置和模型跟踪技术求算反馈和前馈增益阵的主要步骤之后,以CitationⅡ型飞机为算例,设计了其直接升力控制律。计算结果是令人满意的,说明特征结构配置是一种设计飞行控制系统的有效方法。     

推力矢量飞机控制系统设计与仿真研究

针对某型推力矢量飞机提出了一套控制方案,较好地将理论与工程实践结合起来,解决了飞机在全包线范围内的飞行控制问题。该控制方案包括常规机动控制器、大迎角超机动控制器、控制分配器及轨迹跟踪控制器等几个主要环节的设计,完成的控制系统满足全包线飞行品质的要求,可实现对大机动轨迹的精确跟踪。最后,对此综合控制系统进行数字仿真并给出部分仿真结果,结果表明所提出的飞行控制系统设计方案是成功的。     

基于试飞任务单的轨迹仿真问题研究

阐述了基于试飞任务单的试飞轨迹仿真生成软件系统在辅助试飞管理中的重要作用,对该软件开发中所涉及到的一些新的问题和方法进行了研究。建立了带电传操纵系统飞机的数学模型,并针对试飞轨迹仿真生成中的逆问题,提出了一种基准控制带反馈调节的方法。简要介绍了轨迹仿真生成软件与任务单管理数据库软件的接口设计,对仿真结果进行了动态显示处理。     

非线性反馈线性化方法在飞控系统中的应用

应用非线性反馈精确线性化方法进行了飞机自动着陆系统设计。首先,用非线性微分方程组表示的飞机纵向控制系统,在经过输入输出反馈线性化以后,可等效为线性系数;然后,用线性的ＰＩＤ控制方法对变换后的线性系统进行了设计;最后,考虑风的干扰,对所设计的飞机自动着陆控制系统进行了数字仿真。仿真结果表明,用反馈线性化方法设计的飞控系统具有良好的性能。