Integrated active fault-tolerant control using IMM approach

An integrated fault detection, diagnosis, and reconfigurable control scheme based on interacting multiple model (IMM) approach is proposed. Fault detection and diagnosis (FDD) is carried out using an IMM estimator. An eigenstructure assignment (EA) technique is used for reconfigurable feedback control law design. To achieve steady-state tracking, reconfigurable feedforward controllers are also synthesized using input weighting approach. The developed scheme can deal with not only actuator and sensor faults, but also failures in, system components. To achieve fast and reliable fault detection, diagnosis, and controller reconfiguration, new fault diagnosis and controller reconfiguration mechanisms have been developed by a suitable combination of the information provided by the mode probabilities from the IMM algorithm and an index related to the closed-loop system performance. The proposed approach is evaluated using an aircraft example, and excellent results have been obtained     

MIMO变结构飞行重构控制系统设计

基于滑模变结构控制,提出一种MIMO(multiple input multiple output)的飞行重构控制系统的频域设计方法.将滑模变结构控制与飞行重构控制相结合,解决了飞行重构控制技术中故障检测和系统参数辨识的问题.引入渐近观测器和hedge模型增加重构控制系统对衍生未建模动态的鲁棒性;引入作动器模型、输出饱和限制和驾驶员模型,使变结构重构控制系统设计方法变得更为有效和实用;以某型飞机的横航向飞行控制系统为例,进行设计模拟.结果表明:在飞机气动参数大幅突变和操纵面严重受损的情况下,飞机仍能保持良好的性能.      

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.     

Integrated fault estimation and fault-tolerant control for a flexible regional aircraft

The article focuses on the design and application of an active reconfigurable controller that mitigates the effects of gust load and actuator faults on a flexible aircraft. A novel integrated adaptive output feedback scheme is investigated to address the actuator faults. The real-time fault values provided by the fault estimation module are considered in the reconfigurable control law to improve the fault-tolerant capability. The estimate values of faults and control gains are calculated by anal...     

基于神经网络的超机动飞机自适应重构控制

 讨论了一种基于神经网络的超机动飞机直接自适应重构控制方法。飞机的基本控制律采用非线性动态逆方法设计,对于模型不准确和舵面故障等因素导致的逆误差采用神经网络进行在线补偿。通过仿真表明,在飞机发生舵面故障时,神经网络通过自适应地补偿逆误差,可以快速在线重构控制律,保持飞机稳定和一定的操纵品质。     

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.     

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。     

基于自适应动态规划的运载火箭智能姿态容错控制

针对运作火箭主动段发动机摆动执行机构故障下的姿态控制问题,结合自适应动态规划（ADP）方法设计了一种智能容错控制策略。该智能容错控制器主要包括2部分：容错稳定控制部分和优化补偿部分。容错稳定控制部分利用自适应和滑模变结构控制设计,主要维持执行机构故障下姿态控制系统的稳定,保证姿态跟踪误差的有限时间收敛;优化补偿部分采用执行-评价结构,利用ADP的在线学习优势,根据姿态系统的跟踪误差（尤其是系统故障、强干扰导致的跟踪偏差）,设计ADP算法产生补偿控制来进一步优化姿态控制系统的跟踪性能。仿真验证表明,即使存在外部干扰和执行机构故障的情况下,所提方法仍能保证系统稳定且精确跟踪指令信号。     

先进重构飞行控制技术和方法研究

重构飞行控制技术本质上是一种容错飞行控制技术，它使飞控系统具有适应未知故障和损伤的能力，从而可以有效地提高安全性和任务效能。先进重构飞行控制技术在原有的基础上更加强调自适应的能力，而不再依赖故障诊断和隔离（FDI）系统，因而促进了鲁棒控制、智能控制和逢适应控制技术在该领域的交叉和融合。首先回顾了重构飞行控制技术的发展现状，然后给出了几种先进重构控制方法，并总结了先进重构飞行控制技术的主要技术优势，最后展望了它的发展趋势和应用前景。     

基于交互式多模型的飞控系统容错控制研究

针对飞控系统故障引起的参数跳变问题,提出一种基于交互式多模型飞控系统容错控制方法,该算法建立在多个辨识模型和最优二次型控制、特征值配置的基础上.首先,根据作动器故障参数模型设计一系列并行的辨识模型,每个模型对应一种故障;然后,分别采用最优二次型控制和特征值配置的方法设计对应于正常模型和故障模型的控制器;最后,基于交互式...     

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.     

A two-stage approach for managing actuators redundancy and its application to fault tolerant flight control

In safety-critical systems such as transportation aircraft, redundancy of actuators is introduced to improve fault tolerance. How to make the best use of remaining actuators to allow the system to continue achieving a desired operation in the presence of some actuators failures is the main subject of this paper. Considering that many dynamical systems, including flight dynamics of a transportation aircraft, can be expressed as an input affine nonlinear system, a new state representation is adopted here where the output dynamics are related with virtual inputs associated with the intended operation. This representation, as well as the distribution matrix associated with the effectiveness of the remaining operational actuators, allows us to define different levels of fault tolerant governability with respect to actuators’ failures. Then, a two-stage control approach is developed, leading first to the inversion of the output dynamics to get nominal values for the virtual inputs and then to the solution of a linear quadratic(LQ) problem to compute the solicitation of each operational actuator. The proposed approach is applied to the control of a transportation aircraft which performs a stabilized roll maneuver while a partial failure appears. Two fault scenarios are considered and the resulting performance of the proposed approach is displayed and discussed.     

基于多模型的飞控系统自适应重构技术研究

针对飞控系统执行器故障引起参数大范围跳变的问题,提出了一种基于多模型的自适应重构控制方法。建立了执行器故障参数模型,根据故障的特征模型设计一系列并行的辨识模型,采用固定模型与自适应模型相结合的方式,依据转换标准选择与当前飞机状态最匹配的辨识模型所对应的控制器。通过对某型飞机侧向控制系统进行仿真,表明在执行器严重受损的情况下,飞机仍能保持良好的性能。     

卫星姿态时延反步容错控制

针对卫星在轨飞行过程中存在执行机构故障及带有常值干扰的控制问题,提出了一种将时延控制(TDC)与反步技术相结合的鲁棒容错控制方法。该方法在继承反步控制优点的同时,引入积分环节用于减小常值干扰引起的稳态误差;同时,利用TDC的逼近能力来补偿执行机构的故障,且对设计者而言,故障信息不需要进行在线的检测和分离,而仅需要一步状态迭代。基于Lyapunov方法从理论上证明了系统的稳定性。最后,将该方法应用于卫星的姿态调节控制,仿真结果表明该控制器能有效地抑制外部干扰、参数不确定性和执行机构故障的约束,在完成姿态调节控制的同时,具有良好的过渡过程品质。     

Fault-tolerant control with mixed aerodynamic surfaces and RCS jets for hypersonic reentry vehicles

This paper proposes a fault-tolerant strategy for hypersonic reentry vehicles with mixed aerodynamic surfaces and reaction control systems (RCS) under external disturbances and subject to actuator faults. Aerodynamic surfaces are treated as the primary actuator in normal situations, and they are driven by a continuous quadratic programming (QP) allocator to generate torque com-manded by a nonlinear adaptive feedback control law. When aerodynamic surfaces encounter faults, they may not be able to provide sufficient torque as commanded, and RCS jets are activated to augment the aerodynamic surfaces to compensate for insufficient torque. Partial loss of effective-ness and stuck faults are considered in this paper, and observers are designed to detect and identify the faults. Based on the fault identification results, an RCS control allocator using integer linear programming (ILP) techniques is designed to determine the optimal combination of activated RCS jets. By treating the RCS control allocator as a quantization element, closed-loop stability with both continuous and quantized inputs is analyzed. Simulation results verify the effectiveness of the proposed method.     

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.     

Nonlinear adaptive flight control system: Performance enhancement and validation

The problem of decreasing stability margins in L₁ adaptive control systems is discussed and an out-of-loop L₁ adaptive control scheme based on Lyapunov’s stability theorem is proposed. This scheme enhances the effectiveness of the adaptation, which ensures that the system has sufficient stability margins to achieve the desired performance under parametric uncertainty, additional delays, and actuator faults. The stability of the developed control system is demonstrated through a series of simulations. Compared with an existing control scheme, the constant adjustment of the stability margins by the proposed adaptive scheme allows their range to be extended by a factor of 4–5, bringing the stability margin close to that of variable gain PD control with adaptively scheduled gains. The engineered practicability of adaptive technology is verified. A series of flight tests verify the practicability of the designed adaptive technology. The results of these tests demonstrate the enhanced performance of the proposed control scheme with nonlinear parameter estimations under insufficient stability margins and validate its robustness in the event of actuator failures.     

飞机滚转运动的控制余度与重构效能

论证了独立操纵的左右平尾使飞机滚动运动具有较大的控制余度,它增加了飞机正常飞行时的滚转力矩,在飞行中副翼出故障时可进行补偿重构,从而提高了滚动通道的余度等级和飞行的安全性,为减少滚转通道的余度配置提供了依据,通过针对操纵面失效和卡死两类故障的重构设计和仿真也证实了上述结论,同时,初步比较说明了自修复飞控系统在上述故障下的任务可靠性和基本可靠性均高于传统控制系统。     

Robust and adaptive actuator failure compensation designs for a rocket fairing structural-acoustic model

The actuator failure compensation problem is formulated for active vibration control of a rocket fairing structural-acoustic model with unknown actuator failures. Performance of a nominal optimal control scheme in the presence of actuator failures is studied to show the need of effective failure compensation. A robust control scheme and two adaptive control schemes are developed, which are able to ensure the closed-loop system signal boundedness in the presence of actuator failures whose failure pattern and values are unknown. The adaptive scheme for parameterizable failures ensures asymptotic stability despite failure uncertainties. Simulation results verified their failure compensation effectiveness.     

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