Adaptive on-line flux estimation in field-oriented control of an IM

An adaptive technique for the online estimation of the rotor field vector to use as a feedback for the field-oriented control of an induction machine (IM) is described. This method makes use of the stator voltage and rotor speed measurements. It uses the least square estimation technique for identifying the machine parameters to be used in the estimation of the field vector. The position and magnitude of the flux vector are identified during the normal operation of the machine by applying some special constraints to the forcing function. This constraint is applied only for a short duration to make some measurements, and the machine performance is not affected. Extensive simulation of the system has been carried out, and the results are presented     

涡轴发动机自适应非线性预测控制

为了实现当直升机旋翼负载变化时,尽量保持功率涡轮转速恒定,并提高系统动态品质,研究了一种针对涡轴发动机的自适应非线性预测控制(ANMPC)算法.基于涡轴发动机稳态数据和动态特性,采用递归最小二乘法(RLS)进行模型参数辨识,建立了具有在线自适应能力的涡轴发动机数值-ARX(auto regressive with external input)并联预测模型.在此基础上,通过多步输出预测和反馈校正,利用序列二次型优化(SQP)算法,进行在线滚动优化,从而获得了涡轴发动机ANMPC控制器.仿真结果表明:当旋翼负载变化时,相比于传统的串联PID(比例-积分-控制)控制器,ANMPC控制器能够使得功率涡轮转速收敛更快,超调量/下垂量更小.      

Adaptive backstepping-based flight control system using integral filters

A backstepping control design procedure for uncertain nonlinear flight control system expressible in parameter-strict feedback form is presented in this paper. The proposed backstepping procedure, in association with sliding model control technique, exploits the possibility of avoiding, under certain suitable assumptions, the overparameterization problem existing in the classical backstepping process. In particular, a sliding-model-based integral filter is introduced to facilitate the development of the derivation of the virtual inputs, thus reducing the computational load with regard to the standard backstepping procedure. Moreover, in simulations, the control parameters in the resulted controller are optimally tuned using a genetic algorithm so as to show the full potential of the proposed control system.     

Deployable space structure control using adaptive predictive controller with notch filter

The present study addresses the adaptive predictive controller with adaptive notch filter for the tip position control of a deployable space structure model. An adaptive notch filter is designed to estimate multiple bending mode frequencies of the deployable manipulator and to minimize the effect of bending vibration. The results show that the adaptive predictive controller with adaptive notch filter is quite effective controlling the tip position of a deployable space structure under poor modeling information.     

应用保护映射理论的高超声速飞行器自适应控制律设计

针对高超声速飞行器包线范围广、参数变化大的控制需求,应用保护映射理论提出一种高超声速飞行器的自适应控制律设计方法。首先建立整个飞行包线内的线性变参数(LPV)模型,在参数变化边界点设计一个初始的控制结构和参数,然后基于保护映射理论分析初始控制结构使闭环系统稳定的参数范围,通过迭代自动获取整个包线内满足性能指标的控制参数,进而通过多项式拟合设计出高超声速飞行器自适应控制律。所提出的方法能够根据初始控制结构自动寻找一系列满足性能要求的控制器参数,并确定这些控制参数满足闭环系统稳定的设计范围。仿真结果表明,所设计的自适应控制律能够确保高超声速飞行器大包线的设计要求,实现闭环系统的鲁棒稳定。     

Adaptive flow control of low-Reynolds number aerodynamics using dielectric barrier discharge actuator

Aerodynamic performance of low-Reynolds number flyers, for a chord-based Reynolds number of 10⁵ or below, is sensitive to wind gusts and flow separation. Active flow control offers insight into fluid physics as well as possible improvements in vehicle performance. While facilitating flow control by introducing feedback control and fluidic devices, major challenges of achieving a target aerodynamic performance under unsteady flow conditions lie on the high-dimensional nonlinear dynamics of the flow system. Therefore, a successful flow control framework requires a viable as well as accessible control scheme and understanding of underlying flow dynamics as key information of the flow system. On the other hand, promising devices have been developed recently to facilitate flow control in this flow regime. The dielectric barrier discharge (DBD) actuator is such an example; it does not have moving parts and provides fast impact on the flow field locally. In this paper, recent feedback flow control studies, especially those focusing on unsteady low-Reynolds number aerodynamics, are reviewed. As an example of an effective flow control framework, it is demonstrated that aerodynamic lift of a high angle-of-attack wing under fluctuating free-stream conditions can be stabilized using the DBD actuator and an adaptive algorithm based on general input–output models. System nonlinearities and control challenges are discussed by assessing control performance and the variation of the system parameters under various flow and actuation conditions. Other fundamental issues from the flow dynamics view point, such as the lift stabilization mechanism and the influence on drag fluctuation are also explored. Both potentiality and limitation of the linear modeling approach are discussed. In addition, guidelines on system identification and the controller and actuator setups are suggested.     

Adaptive dynamic surface control of NSVs with input saturation using a disturbance observer

An adaptive dynamic surface control(DSC)scheme is proposed for the multi-input and multi-output(MIMO)attitude motion of near-space vehicles(NSVs)in the presence of external disturbance,system uncertainty and input saturation.The external disturbance and the system uncertainty are efficiently tackled using a Nussbaum disturbance observer(NDO),and the adaptive controller is constructed by combining the dynamic surface control technique to handle the problem of‘‘explosion of complexity’’inherent in the conventional backstepping method.For handling the input saturation,an auxiliary system is designed with the same order as that of the studied MIMO attitude system.Using the error between the saturation input and the desired control input as the input of the designed auxiliary system,a series of signals are generated to compensate for the effect of the saturation in the dynamic surface control design.It is proved that the developed control scheme can guarantee that all signals of the closed-loop control system are semi-globally uniformly bounded.Finally,simulation results illustrate that the proposed control scheme can achieve satisfactory tracking performance under the composite effects of the input saturation and the external disturbance.     

Adaptive feedback control of stability in an axial compressor with circumferential inlet distortion

The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed, axial compressor. The flat-baffles with different span heights are used to simulate different distorted inflow cases. Compared with auto-correlation and root-mean-square analysis, cross-correlation analysis used to predict early stall warning does not depend on the distortion position. Hence, the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions. Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios, tip air injection was adopted as the actuator for adaptive feedback control. The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions. The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow. Thus, the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow, which frequently occurs in flight.     

基于滑模控制的四旋翼无人机自适应跟踪控制

针对四旋翼无人机在系统内部模型参数不确定性情况下的轨迹跟踪问题,提出了一种基于滑模控制的四旋翼无人机自适应跟踪控制方法。首先,采用单位四元数来描述系统姿态,将系统分解为位置子系统和姿态子系统;考虑到位置子系统的欠驱动特性,引入了虚拟控制力,跟踪位置信息并解算出实际升力和理想姿态;其次,通过自适应滑模控制器补偿了质量和转动惯量的不确定性,实现了轨迹的跟踪;最后,利用Lyapunov理论证明了闭环系统的稳定性。仿真结果表明了算法的有效性。     

不确定航空发动机分布式控制系统自适应滑模控制

针对存在参数摄动、外部干扰的航空发动机不确定性分布式控制系统,在系统具有时变输入时延和干扰上界未知的情况下,设计了具有鲁棒性能的自适应滑模控制器。基于预测控制和矩阵奇异值理论,对初始的发动机离散分布式模型进行等效线性变换,得到不显含时延项的规范形系统模型,便于进行滑模面参数的求解;在给定的H∞指标下,推导了滑模运动在非匹配不确定性作用下渐进稳定的充分条件,给出了线性矩阵不等式(LMI)形式的滑模面参数设计方法;最后,设计对干扰具有估计功能的自适应率,在此基础上提出自适应滑模控制器。仿真结果表明:所设计的控制器能够有效降低外部干扰对系统动态性能的影响,在所考虑的不确定性因素作用下,系统的滑模运动具有理想的H∞性能。当外部干扰强度变化时,控制器的鲁棒性较好,状态收敛时间小于0.8s,且不存在抖振。      

Wide-range model predictive control for aero-engine transient state

To perform transient state control of an aero-engine, a structure that combines linear controller and min–max selector is widely adopted, which is inherently conservative and therefore limits the fulfillment of the engine potential. Model predictive control is a new control method that has vast application prospects in the field of aero-engine control. Therefore, this paper proposes a wide-range model predictive controller that can control the engine over a wide range within the flight envelope....     

高超声速飞行器单因素融合鲁棒预测控制

针对离线预测控制忽略各个因素对控制律的影响程度,将系统状态变量一维子空间对应的单因素控制量序列进行融合计算,设计了高超声速飞行器的单因素融合鲁棒预测控制器。针对系统的一维子空间离线生成单因素椭圆不变集序列和相应的控制量序列。在线时,在单因素椭圆不变集中分别搜索包含当前状态的最小椭圆,根据当前状态对控制序列进行融合得到控制律。仿真结果表明,相比于传统离线鲁棒预测控制算法,该方法能实现对高度和速度指令的快速、精确跟踪;相比于在线鲁棒预测控制算法,在线计算时间大大减少,实现了对高超声速飞行器的实时控制。     

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     

Adaptive recurrent-neural-network control for linear inductionmotor

In this study an adaptive recurrent-neural-network controller (ARNNC) is proposed to control a linear induction motor (LIM) servo drive. First, the secondary flux of the LIM is estimated with an adaptive flux observer on the stationary reference frame and the feedback linearization theory is used to decouple the thrust force and the flux amplitude of the LIM. Then, an ARNNC is proposed to control the mover of the LIM for periodic motion. In the proposed controller, the LIM servo drive system is identified by a recurrent-neural-network identifier (RNNI) to provide the sensitivity information of the drive system to an adaptive controller. The backpropagation algorithm is used to train the RNNI on line. Moreover, to guarantee the convergence of identification and tracking errors, analytical methods based on a discrete-type Lyapunov function are proposed to determine the varied learning rates of the RNNI and the optimal learning rate of the adaptive controller. The effectiveness of the proposed control scheme is verified by both the simulated and experimental results. Furthermore, the advantages of the proposed control system are indicated in comparison with the sliding mode control system     

Adaptive control and stabilization of elastic spacecraft

This work treats the question of large angle rotational maneuver and stabilization of an elastic spacecraft (spacecraft-beam-tip body configuration). It is assumed that the parameters of the system are completely unknown. An adaptive control law is derived for the rotational maneuver of the spacecraft. Using the adaptive controller, asymptotically decoupled control of the pitch angle of the space vehicle is accomplished, however this maneuver causes elastic deformation of the beam connecting the orbiter and tip body. For the stabilization of the zero dynamics (flexible dynamics), a stabilizer is designed using elastic mode velocity feedback. In the closed-loop system including the adaptive controller and the stabilizer, reference pitch angle trajectory tracking and vibration suppression are accomplished. Simulation results are presented to show the maneuver capability of the control system     

Virtual target guidance-based distributed model predictive control for formation control of multiple UAVs

The paper proposes a Virtual Target Guidance(VTG)-based distributed Model Predictive Control(MPC) scheme for formation control of multiple Unmanned Aerial Vehicles(UAVs).First, a framework of distributed MPC scheme is designed in which each UAV only shares the information with its neighbors, and the obtained local Finite-Horizon Optimal Control Problem(FHOCP) can be solved by swarm intelligent optimization algorithm.Then, a VTG approach is developed and integrated into the distributed MPC scheme...     

航空发动机状态空间模型约束预测控制

为了解决航空发动机约束预测控制器的设计问题，针对状态空间模型，经推导将无约束的二次型性能指标式转换成有约束的二次型性能指标式，采用二次规划方法计算出有约束预测控制量。按无约束和有约束，模型匹配和不匹配分别对某型发动机进行仿真计算，取得了不同约束条件对发动机动态性能和静态性能的影响情况，并举例将仿真数据转换成物理数据。仿真结果符合物理规律，计算方法得到验证。     

基于预测控制的角度约束制导律设计

针对低高度、大倾角末端姿态约束问题,提出了一种弹道跟踪制导律.离线优化得到满足终端约束的基准弹道.为了避免出现奇异,将对位置的跟踪转换为对视线角及视线角速度的跟踪.根据当前状态,利用连续时间非线性预测控制,以弹道跟踪误差和控制能量的组合为性能指标,在线滚动优化得到制导指令,分析了制导律的参数选取,最后对该制导律进行了全...     

Active generalized predictive control of turbine tip clearance for aero-engines

Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed; an implicit active generalized predictive control （GPC）, with auto-regressive （AR） error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per- turbation radius of the system. The active clearance control （ACC） of aero-engine turbine tip clear- ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steadystate and dynamic performance and benefits of increased efficiency, reduced specific fuel consump- tion, and additional service life.     

预测控制综合设计算法设计及软件实现

预测控制综合设计方法通过设计一组满足特定要求的终端约束条件来保证系统的稳定性.给出了一组满足该要求的终端约束条件,然后依据多参数二次规划法求解预测控制器的基本思路,在Matlab环境下设计并实现了一个预测控制综合方法的控制器求解软件,最后通过一个仿真实验验证了该软件的基本功能.仿真结果表明,所设计的软件可以用于求解基于...