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 ...     

基于Kalman滤波的变体飞行器T-S模糊控制

针对变体飞行器的跟踪控制问题,提出了一种基于Kalman滤波的T-S模糊控制方法。考虑飞行器系统状态不可测,引入惯导数据作为辅助信息,利用Kalman滤波算法融合飞控信息与惯导信息实现状态估计。由于变体飞行器在不同变形结构下气动特性变化较大,为便于控制器设计,采用小扰动线性化方法得到飞行器在不同平衡点处的局部线性模型,并通过状态反馈方法设计局部控制器,局部线性模型和局部控制器通过模糊集和模糊规则聚合成一个连续光滑的全局T-S模糊模型和T-S模糊控制器。通过综合Kalman滤波器与T-S模糊控制器得到一个基于Kalman滤波的T-S模糊控制器。仿真结果表明,该控制器在变形过程中能够实现状态估计,保证飞机的跟踪性能。     

Gaussian mixture model based adaptive control for uncertain nonlinear systems with complex state constraints

This paper addresses an uncertain nonlinear control system problem with complex state constraints and mismatched uncertainties. A novel Gaussian Mixture Model(GMM) based adaptive PID-Nonsingular Terminal Sliding Mode Control(NTSMC)(GMM-adaptive-PID-NTSMC)method is proposed. It is achieved by combining a GMM based adaptive potential function with a novel switching surface of PID-NTSMC. Next, the stability of the closed-loop system is proved.The main contribution of this paper is that the GMM meth...     

Neural network-based fault diagnosis for spacecraft with single-gimbal control moment gyros

This paper proposes a neural network-based fault diagnosis scheme to address the problem of fault isolation and estimation for the Single-Gimbal Control Moment Gyroscopes(SGCMGs) of spacecraft in a periodic orbit. To this end, a disturbance observer based on neural network is developed for active anti-disturbance, so as to improve the accuracy of fault diagnosis.The periodic disturbance on orbit can be decoupled with fault by resorting to the fitting and memory ability of neural network. Subsequ...     

基于神经网络的MIMO非线性最小相位系统鲁棒自适应控制

 针对一类模型未知的具有不确定性和外部干扰的多输入多输出（MIMO）非线性最小相位系统提出了鲁棒自适应输出反馈跟踪控制方案。用高斯径向基函数（RBF）神经网络逼近对象未知非线性,用高增益观测器估计系统不可测量状态。所设计的鲁棒自适应控制器不仅能使闭环系统稳定,所有状态有界,而且跟踪误差一致最终有界,并保证最终边界足够小。仿真结果表明了所提出方法的有效性。     

Neural adaptive control for a ground experiment of the space proximity operation in a six-degree-of-freedom micro-gravity simulation system

In this study, a neural adaptive controller is developed for a ground experiment with a spacecraft proximity operation. As the water resistance in the experiment is highly nonlinear and can significantly affect the fidelity of the ground experiment, the water resistance must be estimated accurately and compensated using an active force online. For this problem, a novel control algorithm combined with Chebyshev Neural Networks (CNN) and an Active Disturbance Rejection Control (ADRC) is proposed. Specifically, the CNN algorithm is used to estimate the water resistance. The advantage of the CNN estimation is that the coefficients of the approximation can be adaptively changed to minimize the estimation error. Combined with the ADRC algorithm, the total disturbance is compensated in the experiment to improve the fidelity. The dynamic model of the spacecraft proximity maneuver in the experiment is established. The ground experiment of the proximity maneuver that considers an obstacle is provided to verify the efficiency of the proposed controller. The results demonstrate that the proposed method outperforms the pure ADRC method and can achieve close-to-real-time performance for the spacecraft proximity maneuver.     

Observer-based adaptive sliding mode backstepping output-feedback DSC for spin-stabilized canard-controlled projectiles

This article presents a complete nonlinear controller design for a class of spin-stabilized canard-controlled projectiles.Uniformly ultimate boundedness and tracking are achieved,exploiting a heavily coupled,bounded uncertain and highly nonlinear model of longitudinal and lateral dynamics.In order to estimate unmeasurable states,an observer is proposed for an augmented multiple-input-multiple-output(MIMO) nonlinear system with an adaptive sliding mode term against the disturbances.Under the frame of a backstepping design,an adaptive sliding mode output-feedback dynamic surface control(DSC) approach is derived recursively by virtue of the estimated states.The DSC technique is adopted to overcome the problem of ‘‘explosion of complexity" and relieve the stress of the guidance loop.It is proven that all signals of the MIMO closed-loop system,including the observer and controller,are uniformly ultimately bounded,and the tracking errors converge to an arbitrarily small neighborhood of the origin.Simulation results for the observer and controller are provided to illustrate the feasibility and effectiveness of the proposed approach.     

A new approach to robust fault detection and identification

A methodology for instrument fault detection and identification (FDI) in linear dynamical systems subject to plant parameter variations or uncertainties is presented. At the heart of this approach is a robust estimator for which the necessary and sufficient conditions to its existence are outlined. The robust estimator can simultaneously estimate the unmeasurable state variables of the system for the purpose of control and provide necessary information for FDI purposes. A novel feature of this approach is that it can actually identify the shape and magnitude of the failures. The scheme allows for fast and accurate FDI, and can account for structural uncertainties and variations in the parameters of the dynamical model of the system. The overall fault tolerant control system strategy proposed is verified through simulation studies performed on the control of a vertical takeoff and landing (VTOL) aircraft in the vertical plane     

Adaptive control for feedback-linearized missiles withuncertainties

A robust adaptive control scheme is proposed that can be applied to a practical autopilot design for feedback-linearized skid-to-turn (STT) missiles with aerodynamic uncertainties. The approach is to add a robust adaptive controller to a feedback-linearizing controller in order to reduce the influence of the aerodynamic uncertainties. The proposed robust adaptive control scheme is based on a sliding mode control technique with an adaptive law for estimating the unknown upper bounds of uncertain parameters. A feature of the proposed scheme is that missile systems with aerodynamic uncertainties can be controlled effectively over a wide operating range of flight conditions. It is shown, using Lyapunov stability theory, that the proposed scheme can give sufficient tracking capability and stability for a feedback-linearized STT missile with aerodynamic uncertainties. The six-degree-of-freedom nonlinear simulation results also show that good performance for several uncertainty models and engagement scenarios can be achieved by the proposed scheme in practical night conditions     

一类非线性系统的反演变结构控制及应用

针对一类非线性系统 ,将其变换为易于设计变结构控制规律的规范型。利用小脑关节神经网络( CMAC)估计系统中的不确定函数 ,利用 CMAC神经网络和多面滑模技术估计出变换后系统的状态 ,最后利用变结构控制技术设计出控制器 ,特点是无需已知不确定性函数及其各阶导数的上界 ,与经典设计方法相比 ,所提出的方案允许非参数化不确定性。最后将此方法应用于空空弹控制系统的设计中 ,仿真结果表明了该方法的有效性     

Switched adaptive active disturbance rejection control of variable structure near space vehicles based on adaptive dynamic programming

Based on the switched nonlinear system, a switched adaptive Active Disturbance Rejection Control(ADRC) law is proposed for the Variable Structure Near Space Vehicle(VSNSV) with unknown uncertainties and external disturbances. The reduced-order Extended State Observers(ESOs) are constructed for the attitude angle system and the angular rate system to estimate the total disturbance in real time. With the extended state introduced to counteract the effects of uncertainties and disturbances, a systematic procedure is presented for the synthesis of the switched adaptive ADRC strategy. Rigorous proof shows that the estimation errors of the reduced-order ESOs would converge to a small neighborhood of zero in finite time, and that the output of the closedloop system can track a given signal stably for a class of switching signals with average dwell time via the proposed approach. The variable gain control strategy based on Adaptive Dynamic Programming(ADP) with the actor-critic structure is also designed to improve the dynamic performance of the system. Simulation results verify the effectiveness and advantage of the proposed control scheme.     

High dynamic output feedback robust control of cascaded extended state observer

High dynamic tracking performance is a key technical index of hydraulic flight motion simulator(HFMS). However, the strong nonlinearities, various model uncertainties and measurement noise in hydraulic actuation systems limit the high dynamic performance improvement. In this paper, the outer axis frame of a HFMS is taken as a case study and its nonlinear dynamic model with consideration of strong nonlinearities, matched and mismatched uncertainties is established.A novel cascaded extended state ...     

Acceleration tracking control for a spinning glide guided projectile with multiple disturbances

A novel acceleration tracking controller is proposed in this paper, for a Spinning Glide Guided Projectile (SGGP) subject to cross-coupling dynamics, external disturbances, and parametric uncertainties. The cross-coupled dynamics for the SGGP are formulated with mismatched and matched uncertainties, and then divided into acceleration and angular rate subsystems via the hierarchical principle. By exploiting the structural property of the SGGP, model-assisted Extended State Observers (ESOs) are designed to estimate online the lumped disturbances in the acceleration and angular rate dynamics. To achieve a rapid response and a strong robustness, integral sliding mode control laws and sigmoid-function-based tracking differentiators are integrated into the ESO-based Trajectory Linearization Control (TLC) framework. It is proven that the acceleration tracking controller can guarantee the ultimate boundedness of the signals in the closed-loop system and make the tracking errors arbitrarily small. The superiority and effectiveness of the proposed control scheme in its decoupling ability, accurate acceleration tracking performance and anti-disturbance capability are validated through comparisons and extensive simulations.     

Accelerated Landweber iteration based control allocation for fault tolerant control of reusable launch vehicle

This paper presents a novel Fault Tolerant Control(FTC) scheme based on accelerated Landweber iteration and redistribution mechanism for a horizontal takeoff horizontal landing reusable launch vehicle(RLV). First, an adaptive law based on fixed-time non-singular fast terminal sliding mode control(NFTSMC), which focuses on the attitude tracking controller design for RLV in the presence of model couplings, parameter uncertainties and external disturbances, is proposed to produce virtual control co...     

Nonlinear Adaptive Robust Force Control of Hydraulic Load Simulator

This paper deals with the high performance force control of hydraulic load simulator. Many previous works for hydraulic force control are based on their linearization equations, but hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative control not yield to high-performance requirements. In this paper, a nonlinear system model is derived and linear parameterization is made for adaptive control. Then a discontinuous projection-based nonlinear adaptive robust force controller is developed for hydraulic load simulator. The proposed controller constructs an asymptotically stable adaptive controller and adaptation laws, which can compensate for the system nonlinearities and uncertain parameters. Meanwhile a well-designed robust controller is also developed to cope with the hydraulic system uncertain nonlinearities. The controller achieves a guaranteed transient performance and final tracking accuracy in the presence of both parametric uncertainties and uncertain nonlinearities; in the absence of uncertain nonlinearities, the scheme also achieves asymptotic tracking performance. Simulation and experiment comparative results are obtained to verify the high-performance nature of the proposed control strategy and the tracking accuracy is greatly improved.     

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。     

圆形轨迹导引下的无人机事件触发抗干扰环绕控制

针对内部不确定性以及外部环境摄动的目标环绕控制问题,在基于反步法的双层制导框架下,利用级联控制思想,提出了一种圆形轨迹导引下的四旋翼无人机事件触发抗扰环绕控制方法。在轨迹回路中,构建了可满足持续激励条件的目标位置估计器,保证仅通过视线方位角就能获取可满足最终一致有界条件的目标估计项。随后,基于目标的位置估计结果,设计了目标环绕控制律生成线速度指令,并通过方向向量场验证了该环绕制导律的有效性,消除了现有李雅普诺夫向量场制导(LVFG)对相对位置和目标速度的依赖。在姿态回路中,通过采用扩张状态观测器(ESO)补偿系统的集总不确定性,设计了基于相对阈值事件触发控制的姿态控制器,在有效降低控制器到执行机构之间信号传输频率的同时,实现了四旋翼无人机对静止/移动目标环绕。然后,借助输入状态稳定性定理证明了系统的稳定性。仿真结果表明,所提控制方案能够实现圆形轨迹导引下四旋翼无人机对静止/移动目标的环绕监视。     

RFNN control for PMLSM drive via backstepping technique

A robust fuzzy neural network (RFNN) control system is proposed in this study to control the position of the mover of a permanent magnet linear synchronous motor (PMLSM) drive system to track periodic reference trajectories. First, an ideal feedback linearization control law is designed based on the backstepping technique. Then, a fuzzy neural network (FNN) controller is designed to be the main tracking controller of the proposed RFNN control system to mimic an ideal feedback linearization control law, and a robust controller is proposed to confront the shortcoming of the FNN controller. Moreover, to relax the requirement for the bound of uncertainty term, which comprises a minimum approximation error, optimal parameter vectors and higher order terms in Taylor series, an adaptive bound estimation is investigated where a simple adaptive algorithm is utilized to estimate the bound of uncertainty. Furthermore, the simulated and experimental results due to periodic reference trajectories demonstrate that the dynamic behaviors of the proposed control systems are robust with regard to uncertainties.     

Decentralized attitude synchronization tracking control for multiple spacecraft under directed communication topology

This paper studies the attitude synchronization tracking control of spacecraft formation flying with a directed communication topology and presents three different controllers. By introducing a novel error variable associated with rotation matrix, a decentralized attitude synchronization controller, which could obtain almost global asymptotical stability of the closed-loop system, is developed. Then, considering model uncertainties and unknown external disturbances, we propose a robust adaptive attitude synchronization controller by designing adaptive laws to estimate the unknown parameters. After that, the third controller is proposed by extending this method to the case of time-varying communication delays via Lyapunov–Krasovskii analysis. The distinctive feature of this work is to address attitude coordinated control with model uncertainties, unknown disturbances and time-varying delays in a decentralized framework, with a strongly connected directed information flow. It is shown that tracking and synchronization of an arbitrary desired attitude can be achieved when the stability condition is satisfied. Simulation results are provided to demonstrate the effectiveness of the proposed control schemes.     

Adaptive vector field based accurate homing control of aerial delivery systems

This paper investigates the homing control problem of a flexible aerial delivery system with external wind, at-mospheric turbulence, and aerodynamic uncertainties. An accurate homing control strategy is presented, consisting of a trajectory generation algorithm and a lateral tracking controller. A high-altitude trajectory generation is de-veloped with system characteristics explicitly considered to generate the desired trajectory for the aerial delivery control system design. It significantly compensates for the altitude deviation of the existing multiphase theory based trajectory generation methodologies. A novel adaptive vector field control law is then designed to accom-plish the lateral tracking maneuvers. The key feature of the proposed method is that the complete lateral closed-loop control, including position and heading angle loops, is achieved in the presence of disturbances and dynamic uncertainties. The homing control with high landing accuracy is therefore achieved. Simulation and hardware-in-loop testing results are finally presented to validate the proposed method’s effectiveness compared to a conventional homing control scheme.