Efficient control of a SmartWheel via Internet with compensation of variable delays

Control through networks requires effective strategies due to the presence of induced phenomena. This paper deals with the compensation of the effects of time-varying delays when controlling a delay-dominated system, called SmartWheel (SW), over the Internet in the framework of fractional order control (FOC). In particular, the gains of a nominal fractional order PI^α controller, designed for a local purpose, are adapted with respect to the current delay condition to perform an efficient control over the network. The quadratic stability of the controlled system is proved by a frequency domain method on the basis of switching systems theory. Experimental and simulated results are given to show the effectiveness of the proposed control strategy, referred to the significantly better system performance in comparison with the application of the nominal PI^α, especially for large Internet-induced delays.     

Sliding mode control for an active magnetic bearing system subject to base motion

This paper describes the application of an active magnetic bearing (AMB) system to levitate the elevation axis of an electro-optical sight mounted on a moving vehicle. In this type of system, it is desirable to retain the elevation axis in an air–gap between magnetic bearing stators while the vehicle is moving. A sliding mode control is applied to increase robustness to model uncertainties and to reduce disturbance responses. To ensure the authority of sliding mode control, model parameter uncertainties of AMB systems are analysed and reachability to sliding surface has been verified. The sliding surfaces are designed such that the poles of the closed-loop system locate at desired locations. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. The feasibility of the proposed technique is verified with experimental results.     

台达VE系列变频器在烫金机收卷上的应用

本文介绍了台达VE系列矢量变频器在烫金机收卷上的应用。此类设备使用张力传感器作为反馈,要求张力控制响应快速,且大卷时,电机转速很低,要求低速张力控制同样平稳。台达的VE变频器特有的FOC+PG控制模式不仅可以使电机低速工作时转速工作得很平稳,而且在收卷功能上,提供了2组PID,使变频器可满足客户工艺的严格要求。     

Fractional Chaos Based Communication Systems——An Introduction

As one of secure communication means, chaotic communication systems has been well-developed during the past three decades. Technical papers, both for theoretical and practical investigations, have reached a huge amount in number. On the other hand, fractional chaos, as a parallel ongoing research topic, also attracts many researchers to investigate. As far as the IT field is concerned, the research on control systems by using fractional chaos known as FOC （fractional order control） has been a hot issue for quite a long time. As a comparison, interesting enough, up to now we have not found any research result related to Fractional Chaos Communi- cation （FCC） system, i.e., a system based on fractional chaos. The motivation of the present article is to reveal the feasibility of realizing communication systems based upon FCC and their superiority over the conventional integer chaotic communication systems. Principles of FCC and its advantages over integer chaotic communication systems are also discussed.     

Fractional delay compensated discrete-time SMC for networked control system

Time-varying network induced delay in the communication channel severely affects the performance of closed loop network control systems. In this paper, a novel idea of compensating the fractional time varying communication delay in the sliding surface is presented. The fractional time delay in the sensor to controller and controller to actuator channel is approximated using the Thiran approximation technique to design the sliding surface. A discrete-time sliding mode control law is derived using the proposed surface that compensates fractional time delay in sensor to controller and controller to actuator channels for uncertain network control systems. The sufficient condition for closed loop stability of the system is derived using the Lyapunov function. The efficacy of the proposed strategy is supported by the simulation results.     

Speed sensorless control of a bearingless induction motor with combined neural network and fractional sliding mode

To address the problem of speed and flux observation in sensorless control of a bearingless induction motor under the influence of parameter changes and external disturbances, a speed sensorless control strategy combining radial basis function (radial basis function, RBF) neural network and fractional sliding mode is proposed. According to the current error, fractional sliding mode control rate is designed to reduce the speed-observed chatter of the bearingless induction motor and its adverse effect on the rotor suspension stability. Then, combined with the theory of RBF neural network, the new optimal control rate is obtained by using its approximation ability. At the same time, the stability of two control rate is proved. Thus, the flux linkage and speed under normal operation, parameter change and external disturbance are observed and the new speed sensorless control is realized. The simulation and experimental results show that the proposed joint RBF neural network approximation algorithm and fractional sliding mode speed sensorless control system of the bearingless induction motor can not only effectively identify the flux and speed under three conditions of no-load, load disturbance and speed change, but also ensure the good suspension of the motor rotor in the x-axis and y-axis directions.     

Adaptive minimum energy cognitive lighting control: Integer order vs fractional order strategies in sliding mode based extremum seeking

To achieve comfortable illumination while minimizing the energy consumption in hybrid lighting, a minimum energy point tracking algorithm is developed to achieve the minimized energy usage despite of environmental variations in this paper. A hardware-in-the-loop prototype of an adaptive minimum energy cognitive lighting control is proposed, designed and built. A sliding mode based extremum seeking controller (SM–ESC) including integer order (IO) and fractional-order (FO) strategies is firstly employed to minimize energy usage in the lights, while a PID controller is applied to maintain a light level. The performance of the designed controller is compared with both fractional order and integer order controllers which are designed based the proposed lighting system. The hardware-in-the-loop experimental results are presented to demonstrate the practicality and effectiveness of the proposed cognitive lighting control scheme.     

On the design of sliding mode control schemes for quantum resonantconverters

The design of sliding mode control schemes for quantum resonant converters is introduced hy means of two different approaches. First, an easy-to-use procedure for devising nonlinear control structures is established, using Lyapunov's well-known stability criteria. Second, an alternative method that provides linear sliding surfaces is also developed, considering reaching, existence, and stability conditions. The application of both control design techniques is illustrated in detail by means of three selected examples. The advantages and drawbacks of the resulting control circuits are examined. Simulation and experimental results corroborate the expected features of the close-loop quantum converters     

基于滑模控制的DC-DC降压变换器实验平台

为了实现DC-DC降压变换器的高精度控制,设计了一种基于滑模控制的输出电压调节器。首先根据DC-DC降压变换器的工作原理建立了系统的动态模型;接着利用转换后的受扰动态模型设计了滑模控制器,同时基于李雅普诺夫函数证明了闭环系统的稳定性;最后使用Matlab/Simulink软件和DC-DC降压变换器硬件电路搭建了实验测试平台。测试结果表明与传统的PID控制方法相比,DC-DC降压变换器系统在所设计的滑模控制器的作用下可以获得更快的动态性能与更强的扰动抑制能力。该实验平台不仅有利于大学生理解和掌握滑模控制理论,还可以提高大学生的工程应用能力。     

改进型对称四级光纤环及其制备方法

光纤陀螺是一种重要的导航装置,光纤环(FOC)作为其敏感核心元件决定了光纤陀螺的精度和稳定性。本文针对FOC绕制过程中,边缘光纤匝易产生挤压变形,出现叠丝、塌陷等绕制缺陷,以及FOC绕制效率低等问题,构建了FOC三维仿真模型、分析了边缘非对称四级结构FOC在不同温度载荷下的SHUP误差、优化了光纤环换层绕纤边缘自动控制方法。最后,实际绕纤实验验证了所述方法的有效性。     

A second order sliding mode strategy for fault detection and fault-tolerant-control of a MEMS optical switch

Optical switches are widely used in telecommunication industry due to their many desirable characteristics. In this paper, robust fault detection and fault-tolerant-control (FTC) system for an uncertain nonlinear MEMS optical switch are presented. The design strategy is based on the second order sliding mode approach. A robust second order nonlinear sliding mode observer capable of filtering unwanted high frequencies due to unmodeled dynamics is used to generate quantities called the the residuals. The residuals are then used for the purpose of fault detection and alarm generation. Once an alarm is registered, a fault tolerant control strategy is employed. Two different fault-tolerant control strategies for the unhealthy system are considered. The first strategy is based on conventional sliding mode, while the second is based on a second order sliding mode theory. Robustness and convergence of the proposed schemes are proved using the second method of Lyapunov and the super-twisting algorithm. A comparative study is then performed to demonstrate the superior capability of second order sliding mode control strategy in fault accommodation. Finally, the effectiveness of the proposed strategy for detection of faults, and subsequent control of the MEMS optical switch is illustrated through simulation studies.     

三轴机载光电系统的模糊滑模鲁棒控制方法

为了克服机体振动和气流扰动对三轴机载光电系统对准精度的影响,提出了一种模糊滑模鲁棒控制方法。首先根据坐标转换关系建立了三轴机载光电系统的数学模型,然后引入模糊算法准确估计干扰大小,并设计了模糊滑模鲁棒控制律,最后给出了稳定性分析,能够确保三轴机载光电系统对目标方位的高精度跟踪。仿真结果表明:提出的方法与分数阶控制方法相比,表现出了更优的控制效果,可在300 ms内稳定跟踪指令信号,最大干扰估计误差仅为0.2 N·m,且具有更高的控制精度,对俯仰角、滚转角和航向角的最大跟踪误差分别仅为0.5°、0.7°和0.4°,大幅提高了三轴机载光电系统的对准精度。     

Sliding mode based harmonic oscillator synchronization

This paper deals with the synchronization problem of harmonic oscillatory systems, such as two- and three-phase harmonic oscillators. Synchronization between referent and controlled harmonic oscillators, based on amplitude and phase control, is pursued by employing a variable structure control system. Synchronization is achieved by organizing sliding mode along the intersection of two appropriate nonlinear sliding surfaces, individually providing amplitude and phase identity. In case of three-phase harmonic oscillator synchronization an additional symmetry condition arises, which is handled by introduction of another sliding surface. Parameter perturbations and external disturbances are taken into consideration in control system design. Variable structure controllers for two- and three-phase synchronization are designed, which provide sliding mode along the intersection of sliding surfaces in finite time in spite of present disturbances. Ideal sliding dynamics is proved to be insensitive to internal and external disturbances resulting in an ideal harmonic response. Mathematical analysis as well as experimental and simulation results are presented.     

基于滑模预测的三维起重机防摆控制方法研究

为了使起重机安全、高效运行,同时为了减少附加设备,达到节能减排的目标,运用电子防摆控制方法的研究成了国内外学者广泛关注的课题。本文主要针对桥式起重机三维模型,利用滑模预测的方法来设计控制器,使用预测控制中的滚动优化和反馈校正方法来优化滑模轨迹的到达过程,以最终达到削弱抖振和增强鲁棒性的目的。仿真结果表明,该控制方法可以较好地对起重机系统的大、小车及负载的摆角进行控制,高效的消除起重机的摆动,达到了设计的预期目的。     

采用滑模观测器的机载激光通信视轴精度控制

为了提高机载激光通信系统在机体振动和机械摩擦等扰动下的视轴对准精度,提出了一种基于滑模观测器的反步滑模控制方法。首先建立了机载激光通信系统的数学模型,然后通过设计的滑模观测器对扰动值进行估计,同时针对指令转换模块、激光通信模块和电机模块逐步设计了反步滑模控制律,实现对机载激光通信系统视轴的高精度控制。实验结果表明:提出的方法与分数阶PID控制方法相比突出了更优的快速性和准确性,响应时间仅为0.4 s,最大空间对准误差仅为0.3 m,设计的滑模观测器能够快速、准确地估计出扰动值,响应时间仅为0.3 s,最大估计误差分别仅为0.1 m/s、0.06 (°)/s2 和0.07 A/s,大幅提高了机载激光通信系统中视轴的对准精度。     

自适应模糊滑模控制器设计

针对传统滑模控制的抖振问题,利用线性化反馈技术,将模糊自适应和滑模控制相结合,设计一种新型的模糊滑模控制器。通过模糊推理和基于Lyapunov函数的稳定性分析,获得模糊控制规则的自适应律,构成自适应模糊滑模控制器,有效解决了传统滑模控制中,需要确定参数摄动和外部干扰上确界不确定性问题,倒立摆上的运行结果表明该方法的有效性。     

基于滑模矢量控制的异步电机调速系统

由于异步电机是高阶、非线性、强耦合的多变量系统,难以实现高性能的调速,为此本文在矢量控制基础上,建立了滑模矢量控制异步电机调速系统。首先对系统进行矢量变换,构建电流滞环跟踪PWM矢量变频调速系统,使系统的响应速度增快;其次加入滑模控制,增加系统的鲁棒性和抗干扰能力。最后对异步电机调速系统的模型进行仿真实验,结果表明,增强了滑模矢量控制调速系统负载的抗干扰性,减少了超调量,提高了系统的响应速度。     

Technical note Sliding mode control for a class of hydraulic position servo

The present paper discusses a sliding mode control method suitable for controlling a hydraulic position servo with a flexible load. Due to the requirements of the control system, the reference model is designed for the case of a flexible load. The core of sliding mode control is switching surfaces which are specially defined for the system according to the mathematical model and control goal. A novel algorithm is developed, and the simulated and experimental results of the control system are shown. The results show the extremely good robustness of the proposed method.     

A fault-tolerant strategy based on SMC for current-controlled converters

The sliding mode control (SMC) is used to control variable structure systems such as power electronics converters. This paper presents a fault-tolerant strategy based on the SMC for current-controlled AC–DC converters. The proposed SMC is based on three sliding surfaces for the three legs of the AC–DC converter. Two sliding surfaces are assigned to control the phase currents since the input three-phase currents are balanced. Hence, the third sliding surface is considered as an extra degree of freedom which is utilised to control the neutral voltage. This action is utilised to enhance the performance of the converter during open-switch faults. The proposed fault-tolerant strategy is based on allocating the sliding surface of the faulty leg to control the neutral voltage. Consequently, the current waveform is improved. The behaviour of the current-controlled converter during different types of open-switch faults is analysed. Double switch faults include three cases: two upper switch fault; upper and lower switch fault at different legs; and two switches of the same leg. The dynamic performance of the proposed system is evaluated during healthy and open-switch fault operations. Simulation results exhibit the various merits of the proposed SMC-based fault-tolerant strategy.