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.     

Fault tolerant control system design with explicit consideration of performance degradation

A new approach is proposed for active fault tolerant control systems (FTCS), which allows one to explicitly incorporate allowable system performance degradation in the event of partial actuator fault in the design process. The method is based on model-following and command input management techniques. The degradation in dynamic performance is accounted for through a degraded reference model. A novel method for,selecting such a model is also presented. The degradation in steady-state performance is dealt with using a command input adjustment technique. When a fault is detected by the fault detection and diagnosis (FDD) scheme, the reconfigurable controller is designed automatically using an eigenstructure assignment algorithm in an explicit model-following framework so that the dynamics of the closed-loop system follow that of the degraded reference model. In the mean time, the command input is also adjusted automatically to prevent the actuators from saturation. The proposed method has been evaluated using the lateral dynamics of an F-8 aircraft against actuator faults subject to constraints on the magnitude of actuator inputs. Very encouraging results have been obtained.     

Adaptive Integral-type Sliding Mode Control for Spacecraft Attitude Maneuvering Under Actuator Stuck Failures

A fault tolerant control (FTC) design technique against actuator stuck faults is investigated using integral-type sliding mode control (ISMC) with application to spacecraft attitude maneuvering control system. The principle of the proposed FTC scheme is to design an integral-type sliding mode attitude controller using on-line parameter adaptive updating law to compensate for the effects of stuck actuators. This adaptive law also provides both the estimates of the system parameters and external disturbances such that a prior knowledge of the spacecraft inertia or boundedness of disturbances is not required. Moreover, by including the integral feedback term, the designed controller can not only tolerate actuator stuck faults, but also compensate the disturbances with constant components. For the synthesis of controller, the fault time, patterns and values are unknown in advance, as motivated from a practical spacecraft control application. Complete stability and performance analysis are presented and illustrative simulation results of application to a spacecraft show that high precise attitude control with zero steady-error is successfully achieved using various scenarios of stuck failures in actuators.     

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。     

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.     

Virtual flight test of pitch and roll attitude control based on circulation control of tailless flying wing aircraft without rudders

Circulation Control(CC) realizes rudderless flight control by driving compressed air jet to generate a virtual rudder surface, which significantly improves low detectability. The layout plan of combined control rudder surface is proposed based on the tailless flying wing aircraft. The closed-loop jet actuator system and stepless rudder surface switching control strategy are used to quantitatively study the control characteristics of circulation actuator for pitch and roll attitude through 3-DOF ...     

Robust adaptive fault-tolerant control of a tandem coaxial ducted fan aircraft with actuator saturation

This paper is concerned with the robust adaptive fault-tolerant control of a tandem coaxial ducted fan aircraft under system uncertainty, mismatched disturbance, and actuator saturation. For the proposed aircraft, comprehensive controllability analysis is performed to evaluate the controllability of each state as well as the margin to reject mismatched disturbance without any knowledge of the controller. Mismatched disturbance attenuation is ensured through a structured H-infinity controller tuned by a non-smooth optimization algorithm. Embedded with the H-infinity controller, an adaptive control law is proposed in order to mitigate matched system uncertainty and actuator fault. Input saturation is also considered by the modified reference model. Numerical simulation of the novel ducted fan aircraft is provided to illustrate the effectiveness of the proposed method. The simulation results reveal that the proposed adaptive controller achieves better transient response and more robust performance than classic Model Reference Adaptive Control (MRAC) method, even with serious actuator saturation.     

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.     

Closed-loop dynamic control allocation for aircraft with multiple actuators

A closed-loop control allocation method is proposed for a class of aircraft with multiple actuators. Nonlinear dynamic inversion is used to design the baseline attitude controller and derive the desired moment increment. And a feedback loop for the moment increment produced by the deflections of actuators is added to the angular rate loop, then the error between the desired and actual moment increment is the input of the dynamic control allocation. Subsequently, the stability of the closed-loop dynamic control allocation system is analyzed in detail. Especially, the closedloop system stability is also analyzed in the presence of two types of actuator failures: loss of effectiveness and lock-in-place actuator failures, where a fault detection subsystem to identify the actuator failures is absent. Finally, the proposed method is applied to a canard rotor/wing (CRW) aircraft model in fixed-wing mode, which has multiple actuators for flight control. The nonlinear simulation demonstrates that this method can guarantee the stability and tracking performance whether the actuators are healthy or fail.     

Direct thrust control for multivariable turbofan engine based on affine linear parameter-varying approach

A novel turbofan Direct Thrust Control(DTC) architecture based on Linear ParameterVarying(LPV) approach for a two-spool turbofan engine thrust control is proposed in this paper.Instead of transforming thrust command to shaft speed command and pressure ratio command, the thrust will be directly controlled by an optimal controller with two control variables. LPV model of the engine is established for the designing of thrust estimator and controller. A robust LPV H∞filter is introduced to estimate ...     

Anti-disturbance attitude control of combined spacecraft with enhanced control allocation scheme

In this paper, we propose a novel anti-disturbance attitude control law for combined spacecraft with an improved closed-loop control allocation scheme. More specifically, a saturated approach is adopted to guarantee the global asymptotic stability under control input saturation. To enhance the robustness of the system, a nonlinear disturbance observer is constructed to compensate the disturbances caused by inertial parameter uncertainty and unmodeled dynamics. Next, the quadratic programming algorithm is used to obtain an optimal open-loop control allocation scheme, where both energy consumption and actuator saturation have been considered in the allocation of the virtual control command. Then, a modified closed-loop control allocation scheme is proposed to reduce the allocation error under the actuator uncertainty. Finally, stability analysis of the closed-loop system with the proposed allocation scheme is provided. Simulation results confirm the effectiveness of the proposed control scheme.     

垂尾抖振主动控制的压电作动器布局优化

为了提高压电作动器垂尾抖振主动控制系统的控制性能,提出一种基于输出可控性的压电作动器优化准则。使用压电驱动载荷等效方法建立压电纤维复合材料（MFC）压电作动器力学模型,并建立了带MFC压电作动器垂尾结构模型的动力学方程。在模态可控性和模态价值理论的基础上,提出考虑剩余模态影响的压电作动器优化目标函数。针对垂尾结构的前5阶模态使用遗传算法优化得到压电作动器的布局方案,使用线性二次高斯（LQG）最优控制方法控制垂尾的抖振响应。仿真结果表明,本文优化得到的布局方案比用其他方法能更好地均衡系统的模态可控性,减小剩余模态的影响,获得更好的垂尾抖振响应控制。     

MMAE-based control redistribution applied to the VISTA F-16

A novel control technique, termed control redistribution, is presented and applied in conjunction with multiple model adaptive estimation (MMAE) to the variable in-night stability test aircraft (VISTA) F-16, to detect and compensate for sensor and/or actuator failures. This ad hoc method redistributes control commands (that would normally be sent to failed actuators) to the nonfailed actuators, accomplishing the same control action on the aircraft. Dither is considered to help disambiguate failures in the longitudinal and lateral-directional channels. Detection of both single-actuator and single-sensor failures is considered. Failures are demonstrated detectable in less than 1 s, with an aircraft output nearly identical to that anticipated from a fully functional aircraft in the same environment     

攻击角约束的拦截弹制导控制一体化设计

针对拦截弹的攻击角约束制导问题,提出了一种基于反演滑模和扩张状态观测器(ESO)的制导控制一体化(IGC)设计方法。首先,基于弹目相对运动方程和拦截弹的非线性动力学方程,建立了拦截弹IGC模型,设计了ESO估计目标加速度和自动驾驶仪回路的干扰;在此基础上,基于干扰估计值和反演滑模方法,设计了IGC算法获取虚拟控制力矩,同时基于李雅普诺夫理论分析了闭环系统的稳定性;然后,利用动态控制分配技术将所获取的期望控制力矩分配到实际执行机构;最后,通过仿真结果验证了所设计的IGC+ESO算法的有效性。     

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。     

Phase plane design based fast altitude tracking control for hypersonic flight vehicle with angle of attack constraint

In this paper, fast setpoint altitude tracking control for Hypersonic Flight Vehicle (HFV) satisfying Angle of Attack (AOA) constraint is studied with a two-loop structure controller, in the presence of parameter uncertainties and disturbances. For the outer loop, phase plane design is adopted for the simplified model under Bang-Bang controller to generate AOA command guaranteeing fast tracking performance. Modifications based on Feedback-Linearization (FL) technique are adopted to transform the phase trajectory into a sliding curve. Moreover, to resist mismatch between design model and actual model, Fast Exponential Reaching Law (FERL) is augmented with the baseline controller to maintain state on the sliding curve. The inner-loop controller is based on backstepping technique to track the AOA command generated by outer-loop controller. Barrier Lyapunov Function (BLF) design is employed to satisfy AOA requirement. Moreover, a novel auxiliary state is introduced to remove the restriction of BLF design on initial tracking errors. Dynamic Surface Control (DSC) is utilized to ease the computation burden. Rigorous stability proof is then given, and AOA is guaranteed to stay in predefined region theoretically. Simulations are conducted to verify the efficiency and superior performance of the proposed method.     

Motion synchronization in a dual redundant HA/EHA system by using a hybrid integrated intelligent control design

This paper presents an integrated fuzzy controller design approach to synchronize a dis-similar redundant actuation system of a hydraulic actuator (HA) and an electro-hydrostatic actu-ator (EHA) with system uncertainties and disturbances. The motion synchronous control system consists of a trajectory generator, an individual position controller for each actuator, and a fuzzy force tracking controller (FFTC) for both actuators. The trajectory generator provides the desired motion dynamics and designing parameters of the trajectory which are taken according to the dynamic characteristics of the EHA. The position controller consists of a feed-forward controller and a fuzzy position tracking controller (FPTC) and acts as a decoupled controller, improving posi-tion tracking performance with the help of the feed-forward controller and the FPTC. The FFTC acts as a coupled controller and takes into account the inherent coupling effect. The simulation results show that the proposed controller not only eliminates initial force fighting by synchronizing the two actuators, but also improves disturbance rejection performance.     

High precision attitude dynamic tracking control of a moving space target

On-orbit spacecraft face many threats, such as collisions with debris or other spacecraft.Therefore, perception of the surrounding space environment is vitally important for on-orbit spacecraft.Spacecraft require a dynamic attitude tracking ability with high precision for such missions.This paper aims to address the above problem using an improved backstepping controller.The tracking mission is divided into two phases: coarse alignment and fine alignment.In the first phase,a traditional saturation controller is utilized to limit the maximum attitude angular velocity according to the actuator's ability.For the second phase, the proposed backstepping controller with different virtual control inputs is applied to track the moving target.To fulfill the high precision attitude tracking requirements, a hybrid attitude control actuator consisting of a Control Moment Gyro(CMG) and Reaction Wheel(RW) is constructed, which can simultaneously avoid the CMG singularity and RW saturation through the use of an angular momentum optimal management strategy, such as null motion.Finally, five simulation scenarios were carried out to demonstrate the effectiveness of the proposed control strategy and hybrid actuator.     

考虑执行机构饱和的迎角跟踪控制

设计提出了 1种针对高光谱图像分类任务的 3D-MSCNN模型。在 PCA降维的基础上,利用 3D空谱特征提取网络和 2D多尺度特征提取网络实现高光谱图像特征提取,充分发挥高光谱图像空谱信息价值,增强对不同尺度地表覆盖的表达能力。最后,利用 Softmax分类损失函数实现高光谱图像分类任务。实验结果表明,本文算法在 In. dian Pines和 Pavia University数据集上都取得了较好的分类效果。与 CD-CNN、3D-CNN、SS-Net和 HybirdSN等方法相比,本文算法能够有效提升总体精度、平均精度和 Kappa系数等客观评价指标。     

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.