Design of dynamic dissipative compensators for flexible spacestructures

Control system design is considered for attitude control and vibration suppression of flexible space structures. The problem addressed is that of controlling both the zero-frequency rigid-body modes and the elastic modes. Model-based compensators, which employ observers tuned to the plant parameters, are first investigated. Such compensators are shown to generally exhibit high sensitivity to the knowledge of the parameters, especially the elastic mode frequencies. To overcome this problem, a class of dynamic dissipative compensators is next proposed which robustly stabilize the plant in the presence of unmodeled dynamics and parametric uncertainties. An analytical proof of robust stability is given, and a method of implementing the controller as a strictly proper compensator is described. Methods of designing such controllers to obtain optimal performance and robust stability are presented. Numerical and experimental results of application of the methods are presented, which indicate that dynamic dissipative controllers can simultaneously provide excellent performance and robustness     

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.     

基于内模控制的多输入多输出高阶振动系统

常规的比例-积分-微分(PID)控制器一般用于单输入单输出系统。对于具有多个输入和多个输出且相互之间具有较强耦合作用的高阶多变量系统,PID控制器的设计常难以实现。针对高阶柔性结构振动控制问题,提出如下PID控制策略：首先在某一频段内对频响函数进行拟合降阶,建立过程模型,然后采用内模控制方法和麦克劳林展开式设计多输入多输出振动系统PID控制器。以4层刚架进行建模仿真计算,结果表明,通过本文方法设计的PID控制器,可以在避免未控模态影响的前提下,使外部干扰得到有效抑制,得到比较理想的控制效果。     

Adaptive controller design for a linear motor control system

Three different adaptive controllers for a permanent magnet linear synchronous motor (PMLSM) position-control system are proposed. The proposed controllers include: a backstepping adaptive controller, a self-tuning adaptive controller, and a model reference adaptive controller. The detailed systematic controller design procedures are discussed. A PC-based position control system is implemented. Several experimental results including transient responses, load disturbance responses, and tracking responses of square-wave, sinusoidal-wave, and triangular-wave commands are discussed and compared. The proposed system has a good robustness performance even though the inertia of the system is increased to 10 times. The experimental results validate the theoretical analysis.     

Robust dissipative compensators for flexible spacecraft control

The problem of controller design for flexible spacecraft is addressed. Model-based compensators, which rely on the knowledge of the system parameters to tune the state estimator, are first considered, and are shown to have high sensitivity to parameter uncertainties. Three types of dissipative controllers, which use collocated actuators and sensors, are next considered. These controllers guarantee stability in the presence of unmodeled elastic modes and parameter uncertainties. A procedure is given for designing an optimal dissipative dynamic compensator, which can provide better performance while still retaining robust stability     

A fuzzy sliding-mode controller design for a synchronous reluctancemotor drive

A new method for controlling a synchronous reluctance drive system using a sliding mode with fuzzy controller design is presented. The fuzzy controller is used to adjust the sliding line of the sliding-mode controller. Using this method, the system has a fast response and a good disturbance rejection capability. In addition, the chattering of the speed is reduced. In this work, the mathematical model of the motor is described first. Then, the design procedures for a high performance drive system using a sliding mode with fuzzy control are explained. Next, the system enhanced by a high performance 32 bit digital signal processor (DSP) and simple hardware circuits is shown. Both the current-loop and speed-loop controllers are executed by the DSP. Finally, some experimental and computer simulation results are presented. The experimental results validate the simulation results     

STUDY ON ACTIVE CONTROL FOR A FLEXIBLE BEAM UNDER THE CONDITION OF ZERO GRAVITY

The structure/controlling coupling system is akind of dynamic feedback system in which the me-chanical load and the actuator/controller interact.Because of the influence of inertia,while the com-mon elastic structure is in rigid motion ( or largemotion) ,there inevitably exists a kind of elastic vi-bration ( or small motion) superimposed on thelarge motion.This is the phenomenon of rigid- e-lastic coupling of the motion of an elastic body.Consequently,to study the problem of the motionstabilit…     

基于反步法的挠性航天器姿态镇定

利用反步法研究了一类挠性航天器的姿态镇定问题,提出一种基于模态观测器的反步控制设计方案.首先,构造挠性模态观测器对挠性模态变量及其变化率进行观测;其次,将角速度看成虚拟控制器,设计虚拟角速度镇定运动学模型与挠性模态变量组成的子系统;最后,利用反步法设计了一种非线性控制器使得角速度能够跟踪虚拟角速度,从而实现姿态镇定的目...     

Non-fragile switching tracking control for a flexible air-breathing hypersonic vehicle based on polytopic LPV model

This article proposes a linear parameter varying (LPV) switching tracking control scheme for a flexible air-breathing hypersonic vehicle (FAHV). First, a polytopic LPV model is constructed to represent the complex nonlinear longitudinal model of the FAHV by using Jacobian linearization and tensor-product (T-P) model transformation approach. Second, for less conservative controller design purpose, the flight envelope is divided into four sub-regions and a non-fragile LPV controller is designed for each parameter sub-region. These non-fragile LPV controllers are then switched in order to guarantee the closed-loop FAHV system to be asymptotically stable and satisfy a specified performance criterion. The desired non-fragile LPV switching controller is found by solving a convex constraint problem which can be efficiently solved using available linear matrix inequality (LMI) techniques, and robust stability analysis of the closed-loop FAHV system is verified based on multiple Lypapunov functions (MLFs). Finally, numerical simulations have demonstrated the effectiveness of the proposed approach.     

Robustness of Velocity Feedback Controllers for Flexible Spacecraft

The robustness properties of collocated velocity feedback controllers used for damping enhancement in large, flexible space structures are investigated. It is proved that the closed-loop system using such controllers is asymptotically stable in the large when: 1) unmodeled linear time-invariant dynamics (such as sensors/actuators) are present, provided that the phase angle of such dynamics is between -90° and 90°, 2) time-varying or invariant nonlinearities lying in the first and the third quadrant (i. e., belonging to the (0, ?) sector) are present, or 3) sector-type nonlinearities following first-order stable dynamics are present in the feedback loop.     

气动FA补偿变结构Bang-Bang位置伺服算法

 首先提出了一种基于两位两通高速开关阀的无杆气缸脉宽调制（PWM）控制方案,为气缸提供了中位截止机能。然后针对Bang-Bang控制算法中存在的超调和振荡现象,提出了摩擦力和加速度（FA）补偿的变结构Bang-Bang算法。该算法综合位置和速度误差的影响构造了加速度方向切换评价函数,考虑了摩擦力对控制量设定的影响,分别依据阶跃函数、线性函数和反正切函数对活塞加速度值进行动态设定,实现了运动过程中对活塞摩擦力的补偿和加速度的调整。最后,利用该算法进行了无杆气缸的带载伺服定位试验,对3种加速度设定函数的控制效果做了比较。结果证明FA补偿变结构算法在提高气缸定位精度方面有显著效果。     

飞行/推进系统分散控制优化设计及鲁棒性分析

以一种短距起降战斗机的飞行/推进综合控制系统设计为背景,对分散控制如何保持集中控制的性能和鲁棒性的问题提出利用优化的思想设计分散控制器.首先采用遗传算法设计集中控制器,作为分散控制的性能参考,然后给出具有接口变量的分散控制器设计方法,通过分析得出影响分散控制性能的关键因素,并通过数学推导得到以频率加权矩阵为设计参数的分散控制性能表达式,将分散控制器设计转化为优化问题,采用遗传算法求解得到分散控制器.分散控制器设计中同时用到了一种改进的平衡降阶方法.通过仿真和结构奇异值分析验证了这种优化设计方法可使分散控制达到集中式控制的性能和鲁棒性.      

Sensor/actuator placement for flexible space structures

A new approach for the placement of sensors and actuators in the active control of flexible space structures is developed. The approach converts the discrete nature of sensor and actuator positioning problems to a nonlinear programming optimization through approximation of the control forces and output measurements by spatially continuous functions. The locations of the sensors and actuators are optimized in order to move the transmission zeros of the system further to the left of the imaginary axis. This criterion for sensor/actuator placement can be useful for optimal regulation and tracking problems, as well as for low authority controller designs. Two performance metrics are considered for the optimization and are applied to the sensor/actuator positioning of a large-order flexible space structure     

Nonlinear observer and output feedback attitude control ofspacecraft

The problem of controlling a spacecraft by measuring only the angular position (roll, pitch, and yaw) is considered. A nonlinear observer is proposed which asymptotically reconstructs all the spacecraft state variables; if the spacecraft actuators are reaction wheels, the angular velocities of the wheels also must be measured. It is shown that if the observer is used in connection with asymptotically stable state feedback controllers, the extended system (spacecraft, controller, and observer) is still asymptotically stable. Simulation results are reported to illustrate the dynamic behavior of the observer     

Simple adaptive control of large flexible space structures

Simple adaptive control procedures that do not require explicit parameter identification have been shown to be fit for control of large systems such as flexible structures. It is of interest, however, to test their robustness when fast adaptation is needed or when the resulting adaptive control system must confront finite sensor and actuator dynamics or parasitic disturbances. Flexible structures case studies using parallel feedforward and simplified adaptive controllers are used to present a robust adaptive control solution to these problems. The detailed proof of robust stability of the adaptive control system is also presented. Simulations illustrate the simplicity of implementation and the power of the proposed algorithm in difficult realistic situations     

涡轴发动机双回路PI控制器多发功率匹配

为了应对多个发动机共同驱动同一直升机时,单个发动机性能衰退所引发的输出功率不平衡问题,以控制2个转子转速的双回路结构PI控制器为基础,将外回路改为直接功率控制回路,搭配能够计算旋翼在一定转速下需求功率的机载模型,构建了1种涡轴发动机多发功率平衡匹配控制系统.内回路分别采用燃气发生器转子转速控制回路和动力涡轮转子转速控制回路,得到参数不同的控制器并进行了仿真验证和对比.结果表明:所设计的双回路PI控制器能够在保证涡轴发动机动力涡轮转速恒定的同时,使性能衰退程度不同的2台发动机输出相同的功率.     

Novel sliding mode controller for synchronous motor drive

A novel sliding mode controller with an integral-operation switching surface is proposed. Furthermore, an adaptive sliding mode controller is investigated, in which a simple adaptive algorithm is utilized to estimate the bound of uncertainties. The position control for a permanent magnet (PM) synchronous servo motor drive using the proposed control strategies is illustrated. The theoretical analysis and the theorems for the proposed sliding mode controllers are described in detail. Simulation and experimental results show that the proposed controllers provide high-performance dynamic characteristics and are robust with regard to plant parameter variations and external load disturbance     

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。     

基于多模型切换的鲁棒自适应控制器

系统参数发生跳变时,为了解决多变量系统暂态响应变差的问题,提出一种基于多模型切换的鲁棒自适应控制器。该控制器由多个鲁棒自适应控制器组成,鲁棒自适应控制器保证系统存在未建模动态时能够使自适应系统稳定运行,引入的多模型策略保证系统参数跳变时具有良好的暂态性能。仿真结果表明,所提出的多模型鲁棒自适应控制器能够加快系统的响应速度,提高系统的暂态性能。     

空中交通管制员的眼动行为与疲劳关系

在空中交通管制工作中,管制疲劳程度度量是一项需要长期研究的重要课题。实时测量管制员的疲劳程度,对航空运输系统的安全运行有重要意义。提出以眼动行为特征指标作为反映管制员疲劳程度的依据,利用faceLAB 5.0系统记录了管制员在正常状态和疲劳状态下进行管制模拟实验的眼动数据和绩效数据,分析了管制员的绩效数据与眨眼频率和瞳孔直径两种眼动指标在不同状态下的变化规律。研究发现与正常状态相比,管制员在疲劳状态下的眨眼频率增加,瞳孔直径减小。随着任务时间的增加,被试的绩效变差,眨眼频率增加,瞳孔直径减小,表明被试的工作状态从正常状态转为疲劳状态。统计分析结果说明,眨眼频率和瞳孔直径能够有效地检测管制员的疲劳状态,充分刻画不同工作时段管制员工作状态的变化,为开发实用的疲劳监测系统提供理论基础。