Finite-time sliding mode attitude control for a reentry vehicle with blended aerodynamic surfaces and a reaction control system

This paper proposes a finite-time robust flight controller, targeting for a reentry vehicle with blended aerodynamic surfaces and a reaction control system(RCS). Firstly, a novel finite-time attitude controller is pointed out with the introduction of a nonsingular finite-time sliding mode manifold. The attitude tracking errors are mathematically proved to converge to zero within finite time which can be estimated. In order to improve the performance, a second-order finite-time sliding mode controller is further developed to effectively alleviate chattering without any deterioration of robustness and accuracy. Moreover, an optimization control allocation algorithm, using linear programming and a pulse-width pulse-frequency(PWPF) modulator, is designed to allocate torque commands for all the aerodynamic surface deflections and on–off switching-states of RCS thrusters.Simulations are provided for the reentry vehicle considering uncertain parameters and external disturbances for practical purposes, and the results demonstrate the effectiveness and robustness of the attitude control system.     

离散RCS的PWPF调制方式改进及混合控制逻辑设计

可重复使用飞行器(RLV)再入控制常涉及离散的反推力控制系统(RCS)和连续的气动舵面的混合控制,其中避免离散RCS出现极限环振荡和混合控制的逻辑是设计的关键问题。为此,对应用脉宽脉频(PWPF)调制的离散RCS进行极限环振荡行为的离散描述函数法预测,推导极限环出现条件,设计了一种前置非对称死区环节规避极限环而不损失性能,在此基础上提出便于工程应用的RCS与气动舵面混合控制逻辑。通过对典型飞行器的控制仿真验证表明,改进的离散RCS的PWPF调制方式及设计的混合控制逻辑能够获得良好的控制效果,满足控制要求。     

姿控式直接侧向力与气动力复合控制策略设计

针对自旋导弹直接侧向力与气动力复合控制问题,提出一种分阶段复合控制策略,该策略充分考虑了直接侧向力离散控制和空气舵连续控制的特点,将弹体迎角和侧滑角响应过程分为上升段和保持段以实现快速精确跟踪。上升段考虑固体脉冲发动机的快响应特性,利用整数线性规划(ILP)得到了需要开启的脉冲发动机数量,产生直接侧向力控制导弹快速建立迎角和侧滑角。保持段则基于动态逆控制和自抗扰控制技术,通过空气舵控制迎角和侧滑角稳定在期望值,以克服侧向喷流干扰效应和大迎角飞行带来的非线性耦合的影响。仿真结果表明,依靠直接侧向力与气动力的分时串联作用,可以有效地抑制复合系统的外扰和模型不确定性的影响,显著加快拦截导弹的过载响应速度。     

基于输出预测的姿控发动机控制律优化设计

针对带有侧向喷流姿控发动机和尾部气动舵的导弹,建立了系统动力学模型和运动学模型,并对模型进行了分析和简化;考虑到侧向过载输出响应快速性的要求,采用侧向喷流发动机提供姿态控制力矩快速建立过载。基于侧向喷流发动机的工作特点,采用Fliess展式得到侧向过载输出的预测和侧向喷流发动机推力放大因子的估计,并以此为基础,提出了以侧向喷流发动机为执行机构的姿态控制律优化设计方法,实现了对侧向过载的快速跟踪。仿真结果说明了所提出方法的有效性。     

基于布谷鸟搜索算法的一类变体飞行器容错控制

针对一类存在执行机构故障的分布式结构变体飞行器的控制分配问题,结合整数规划理论,提出一种基于布谷鸟搜索算法的容错控制方法。首先,设计虚拟控制指令,使得系统状态能够很好地跟踪参考模型;然后,将执行器概率性故障与饱和约束转换为整数规划问题中决策变量的约束,从而将执行器控制分配问题转化为一类整数规划问题;最后,采用改进的布谷鸟搜索算法进行求解,得到实际的执行器控制分配指令。仿真结果表明,在执行器存在概率性故障的情况下,该容错控制方法较无容错策略的情况能够有效提升系统的跟踪性能;与遗传算法相比,该算法得到的执行器控制分配结果更加精确。     

基于基排序的推力矢量飞机控制分配方法

为了解决推力矢量战机存在的执行机构冗余和气动/矢量操纵面协调控制问题,基于过驱动控制理论及控制分配理论, 提出一种基于基排序的操纵面调度管理分配算法。综合推力矢量飞机各型操纵面的物理特性差异、转矩可达集大小、推力矢量工 作时间限制等因素,划分基控制组。采用优先级为主气动控制组、辅助气动控制组、推力矢量控制组的3级串接链分配构型,按指 令幅值依序调度各级操纵面。结果表明：算法分配过程清晰灵活,飞行控制品质优良,对飞行任务与操纵面故障适应性强,可保证 战机高效完成各项任务。相较于传统伪逆方案,新算法在典型“眼镜蛇”机动过程中,削减矢量偏转工作时长超50%,降低最大偏 转角超3°。该算法可规避传统分配方法无差别调度气动/矢量操纵面的缺陷,优化推力矢量启用时间,有效解决飞机操纵能力扩 展与矢量装置寿命平衡的矛盾。     

基于线性规划的多操纵面重构控制研究

为实现多操纵面飞机的重构控制,提高飞机飞行的安全性能,提出了一种基于线性规划的多操纵面重构控制策略.针对操纵面卡死、松浮、损伤等典型故障情况,推导了相应的重构分配器,通过基于线性规划的直接分配方法来实现在操纵面故障下的重构控制.仿真结果表明,该控制策略能有效处理典型操纵面故障,发生故障时仍能快速跟踪控制指令,保证较好的...     

基于干扰观测器的四旋翼无人机离散时间容错控制

为了飞行控制方案便于在计算机上实现，针对具有外部干扰和执行器加性故障的四旋翼无人机（UAV）角度运动方程，给出一种基于干扰观测器的离散时间跟踪控制方案。通过设计离散时间干扰观测器抑制外部干扰和执行器故障的不利影响，并结合干扰观测器设计离散时间控制器。通过数值仿真验证了基于干扰观测器的离散时间容错控制方案的有效性。仿真结果表明，设计的离散控制器能够保证外部干扰和执行器故障综合作用下的四旋翼UAV系统跟踪控制性能。     

RLV再入姿态双环滑模控制及舵喷混合配置

应用滑模控制设计了一种可重复使用运载器（RLV）再入姿态控制器,该控制器应用双环的滑模控制方案,可以获得对角速度及角度的同时跟踪,并具有较好的鲁棒性和解耦性能。针对RLV再入姿态的动力面与反作用混合控制的特点,运用优化控制选择配置算法把控制力矩指令配置为末端受动器的控制指令,分别由动力面与反作用致动器来执行。再入姿态仿真验证了该方法的精度、鲁棒性以及解耦的跟踪性能及有效性。     

航天器自适应快速非奇异终端滑模容错控制

针对存在外部干扰、转动惯量矩阵不确定、控制器饱和以及执行器故障的航天器姿态跟踪控制问题,提出了基于自适应快速非奇异终端滑模的有限时间收敛控制方案。通过引入能够避免奇异点的具有有限时间收敛特性的快速非奇异终端滑模面,设计了满足多约束的有限时间姿态跟踪容错控制器,并利用参数自适应方法使控制器设计不依赖于系统惯量信息和外部干扰的上界。此外,所设计的控制器显式考虑了执行器输出力矩的饱和幅值特性,使航天器在饱和幅值的限制下完成姿态跟踪控制任务,并且无须进行在线故障估计。Lyapunov稳定性分析表明：在外部干扰、转动惯量矩阵不确定、控制器饱和以及执行器故障等约束条件下,所设计的控制器能够保证闭环系统的快速收敛性,而且对控制器饱和与执行器故障具有良好的容错性能。数值仿真校验了该控制器在姿态跟踪控制中的优良性能。     

气动舵面/RCS复合控制系统构型设计与仿真

针对空天飞行器再入段异构执行机构复合控制问题,基于气动舵面和反作用推力器的特性,提出了适用于空天飞行器的3种气动舵面与反作用控制系统的复合控制构型：指令型、力矩型、指令误差型,以及相应的控制律设计方法,在此基础上完成空天飞行器再入段的控制系统设计。仿真结果表明,3种构型的复合控制系统均能满足指令跟踪性能要求,其中指令型复合控制系统气动舵工作最为平稳,推力器开启频次最少。从工程应用的角度出发,指令型复合控制系统的综合性能最为理想。     

RCS对舵面控制特性影响的数值模拟

可重复使用运载器等采用反作用控制系统（RCS）/舵面复合控制技术进行配平和控制,由于舵面和喷口的位置相距很近,同时工作时将产生相互干扰效应。采用非定常数值模拟方法,结合动网格技术和喷流模拟技术,针对可重复使用运载器外形开展了侧向喷流开启和关闭对舵面控制特性的影响研究,分析了飞行器俯仰运动对不同舵面操纵方式的动态响应过程。研究发现,在超声速来流条件下,侧向喷口前方的弓形激波会打到方向升降舵的下表面产生一个局部高压区,使得飞行器产生附加的低头力矩,导致喷流开启时的配平攻角相对关闭时要低约1°。同时,侧向喷流与襟副翼之间存在非定常、非线性干扰现象,在RCS/舵面复合控制系统设计时,需要对此进行一定的补偿。     

Robust adaptive compensation control for unmanned autonomous helicopter with input saturation and actuator faults

This paper studies a robust adaptive compensation Fault Tolerant Control(FTC) for the medium-scale Unmanned Autonomous Helicopter(UAH) in the presence of external disturbances,actuator faults and input saturation.To improve the disturbance rejection capacity of the UAH system in actuator healthy case, an adaptive control method is adopted to cope with the external disturbances and a nominal controller is proposed to stabilize the system.Meanwhile, compensation control inputs are designed to reduce the negative effects derived from actuator faults and input saturation.Based on the backstepping control and inner-outer loop control technologies, a robust adaptive FTC scheme is developed to guarantee the tracking errors convergence.Under the presented FTC controller, the uniform ultimate boundedness of all closed-loop signals is ensured via Lyapunov stability analysis.Simulation results demonstrate the effectiveness of the proposed control algorithm.     

Reconfigurable fault-tolerant control for supersonic missiles with actuator failures under actuation redundancy

Aircraft undergoing actuator failures into under-actuation have been seldom studied in literature. Aiming at addressing actuator failures of Total Loss of Effectiveness (TLOE) as well as Partial Loss of Effectiveness (PLOE) resulting in different system actuations, reconfigurable Fault-Tolerant Control (FTC) is proposed for supersonic wingless missiles under actuation redundancy. The under-actuated system of TLOE failure patterns is solved by transformation to cascade systems through a ‘shape variable’. Meanwhile, actuator TLOE faults of different unknown failure patterns from proper actuation to under-actuation are accommodated by a reconfigurable adaptive law on a multiple-model basis. The backstepping technique with the Extended State Observer (ESO) method adopted as a basic strategy is applied to an established symmetric coupled missile system with actuator PLOE faults, modeling errors, and external disturbances. Additionally, the nonlinear saturation characteristics of actuators are settled by an auxiliary system with the Nussbaum function technique. The stability of the control system is analyzed and proven through Lyapunov theory. Numerical simulations are implemented in the presences of aerodynamic uncertainties, gust disturbance, and actuator failures. Results demonstrate the effectiveness of the proposed method with satisfactory tracking performance and actuator fault tolerance capacity.     

基于自适应滑模与模糊控制的导弹直接力/气动力复合控制系统优化设计

 针对导弹直接力/气动力复合控制问题,提出了一种基于自适应滑模控制(ASMC)与模糊逻辑的自动驾驶仪设计方法。该方法将整个导弹控制系统分为气动力控制子系统(ACS)和直接力控制子系统(RCS)两部分。前者采用自适应滑模控制理论进行设计,利用其所具有的强鲁棒性优点,克服了包括参数摄动与外界扰动在内的各类不确定性因素的影响。后者通过基于规则的模糊推理来确定不同条件下直接力作用的大小,以辅助提高气动力子系统的性能。在控制系统结构确定的条件下,利用遗传算法(GA)对各参数进行优化,实现了两个子系统之间的协调工作。仿真结果表明,所提出的控制方案对机动指令具有较好的跟踪效果,适用于直接力/气动力复合控制导弹的控制系统设计。     

Reconfigurable NDI controller using inertial sensor failuredetection & isolation

A modified derivation of nonlinear dynamic inversion provides the theoretical underpinnings for a reconfigurable control law for aircraft that have suffered combinations of actuator failures, missing effector surfaces, and aerodynamic changes. The approach makes use of acceleration feedback to extract information pertaining to any aerodynamic change and thus does not require a complete aerodynamic model of the aircraft. The control law does require feedback of effector positions to accommodate actuator dynamics. Both accelerometer and rate gyro failure detection and isolation (FDI) systems are implemented, allowing up to three independent failures for each FDI system as long as they are in different axes. Nonlinear simulation results show that the FDI systems improve the robustness to accelerometer/rate gyro uncertainties. An advanced tailless aircraft model is used to demonstrate the concepts. The simulation includes accelerometer and rate gyro noise and bias, failures due to accelerometers, rate gyros, and actuators, and modeled missing surfaces that cause airplane aerodynamic changes     

考虑预设性能约束的运输机姿态容错控制

针对运输机舵面故障情况下的姿态容错控制问题,提出了一种考虑预设性能约束的自适应指令滤波增量反步(Adaptive Command-filtered Incremental Backstepping,ACFIBS)容错控制器。首先,构造运输机故障模型,在反步控制设计结构下,通过构造预设性能函数,保证外回路姿态角跟踪误差的动态性能。然后,考虑舵机偏转速率和幅值限制,引入受限指令滤波器和补偿信号,综合考虑气动参数不确定性,采用增量方法设计反步内环控制律。在此基础上,进一步考虑舵面故障情况,引入自适应方法及低通滤波器改进增量反步控制器。最后,通过理论推导和仿真试验验证了控制方法的有效性。仿真结果表明,所设计的控制器具有良好的容错性能,在不同舵面故障条件下均可实现对指令信号的预设性能跟踪,且在参数摄动情况下具有较强的鲁棒性。     

基于泵式流体回路的小卫星姿控/热控一体化执行机构设计

 主要研究了小卫星姿控/热控一体化执行机构的设计问题.首先,根据流体回路中液体流速变化对小卫星产生力矩实现姿态控制、液体流动吸/散废热实现热控制的原理,提出一种姿控/热控一体化执行机构设计方案.然后针对该设计方案,利用以电机转速为变量的流体回路内压强和电磁力矩方程,推导了一体化执行机构姿控力矩模型;利用散热量随流体回路流速的变化,建立了一体化执行机构热控模型.最后,针对某小卫星设计了基于姿控/热控一体化执行机构的闭环控制系统,并针对该一体化执行机构设计了一种姿控/热控解耦算法,对其姿控/热控能力进行数学仿真验证,仿真结果证明了该一体化执行机构的有效性.     

Adaptive Fuzzy Torque Control of Passive Torque Servo Systems Based on Small Gain Theorem and Input-to-state Stability

Passive torque servo system (PTSS) simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturbance is called extra torque. The most important issue for PTSS controller design is how to eliminate the influence of extra torque. Using backstepping technique, adaptive fuzzy torque control (AFTC) algorithm is proposed for PTSS in this paper, which reflects the essential characteristics of PTSS and guarantees transient tracking performance as well as final tracking accuracy. Takagi-Sugeno (T-S) fuzzy logic system is utilized to compensate parametric uncertainties and unstructured uncertainties. The output velocity of actuator identified model is introduced into AFTC aiming to eliminate extra torque. The closed-loop stability is studied using small gain theorem and the control system is proved to be semiglobally uniformly ultimately bounded. The proposed AFTC algorithm is applied to an electric load simulator (ELS), and the comparative experimental results indicate that AFTC controller is effective for PTSS.     

Robust fault-tolerant control for wing flutter under actuator failure

Many control laws, such as optimal controller and classical controller, have seen their applications to suppressing the aeroelastic vibrations of the aeroelastic system. However, those control laws may not work effectively if the aeroelastic system involves actuator faults. In the current study for wing flutter of reentry vehicle, the effect of actuator faults on wing flutter system is rarely considered and few of the fault-tolerant control problems are taken into account. In this paper, we use the radial basis function neural network and the finite-time H_∞ adaptive fault-tolerant control technique to deal with the flutter problem of wings, which is affected by actuator faults, actuator saturation, parameter uncertainties and external disturbances. The theory of this article includes the modeling of wing flutter and fault-tolerant controller design. The stability of the finite-time adaptive fault-tolerant controller is theoretically proved. Simulation results indicate that the designed fault-tolerant flutter controller can effectively deal with the faults in the flutter system and can promptly suppress the wing flutter as well.