磁悬浮永磁直线电动机非脆弱鲁棒H∞控制器设计

基于线性矩阵不等式(LMI)理论,提出设计非脆弱鲁棒控制器来抑制不确定因素的影响以及控制器参数摄动.首先,采用矢量控制方法中的id=0控制策略,把非线性系统解耦成独立的线性电流子系统和速度子系统.其次,根据H∞性能指标与线性矩阵不等式的等价性,将控制器设计转化为对LMI的求解.最后,为了验证其有效性,在MATLAB环境下对控制系统进行仿真研究.通过研究可知,非脆弱鲁棒控制器能在容许的增益摄动下以及存在不确定性干扰时,系统不仅具有鲁棒性而且还是非脆弱的,从而保证闭环系统具有良好的鲁棒性.     

基于LMI的磁悬浮永磁直线电动机H∞鲁棒控制器的设计

针对磁悬浮永磁直线电动机中的不确定性扰动,提出基于线性矩阵不等式( LMI)方法设计进给系统的H∞鲁棒控制器.首先,采用矢量控制方法中的id=0控制策略,把非线性系统解耦成独立的线性电流子系统和速度子系统.其次,根据H∞性能指标与线性矩阵不等式的等价性,将设计问题转化为对LMI的求解,进而得到磁悬浮永磁直线电动机系统的状态反馈H∞控制器.最后,为了验证设计的有效性,在MATLAB环境下应用Simulink建立系统的仿真模型,对控制系统进行仿真研究,结果表明所设计的H∞控制器满足对不确定性扰动抑制的要求.     

Analytical method for constrained mechanical and structural systems

The objective of this study is to present an accurate and simple method to describe the motion of constrained mechanical or structural systems. The proposed method is an elimination method to require less effort in computing Moore-Penrose inverse matrix than the generalized inverse method provided by Udwadia and Kalaba. Considering that the results by numerical integration of the derived second-order differential equation to describe constrained motion veer away the constrained trajectories, this study presents a numerical integration scheme to obtain more accurate results. Applications of holonomically or nonholonomically constrained systems illustrate the validity and effectiveness of the proposed method.     

Implementation of a robust dynamic control for SCARA robot

A control system for SCARA robot is designed for implementing a robust dynamic control algorithm. This study focuses on the use of DSPs in the design of joint controllers and interfaces in between the host controller and four joint controllers and in between the joint controllers and four servo drives. The mechanical body of SCARA robot and the servo drives, are selected from the commercially available products. The four joint controllers, assigned to each joint separately, are combined into a common system through the mother board hardwarewise and through the global memory softwarewise. The mother board is designed to connect joint controllers onto the board through the slots adopting PC/104 bus structures. The global memory stores the common data which can be shared by joint controllers and used by the host computer directly, and it virtually combines the whole system into one. To demonstrate the performance and efficiency of the system, a robust inverse dynamic algorithm is proposed and implemented for a faster and more precise control. The robust inverse dynamic algorithm is basically derived from an inverse dynamic algorithm and a PID compensator. Based upon the derived dynamic equations of SCARA robot, the inverse dynamic algorithm is initially implemented with l msec of control cycle—0.3 msec is actually used for the control algorithm—in this system. The algorithm is found to be inadequate for the high speed and precision tasks due to inherent modelling errors and time-varying factors. Therefore a variable PID algorithm is combined with the inverse dynamic algorithm to reinforce robustness of control. Experimental data using the proposed algorithm are presented and compared with the results obtained from the PID and the inverse dynamic algorithms.     

Robust state estimation for a class of uncertain nonlinear systems: Comparison of two approaches

In this paper, two approaches for robust state estimation of a class of Lipschitz nonlinear systems are proposed. First, a novel Unknown Input Observer (UIO) is designed without observer matching condition satisfaction. Then, an $H_{\infty }$ observer for approximate disturbance decoupling is proposed. Sufficient conditions for the existence of both proposed observers are derived based on a Lyapunov function. The achieved conditions are formulated in terms of a set of linear matrix inequalities (LMIs) and optimal gain matrices are obtained. The minimum values of the disturbance attenuation levels for both methods are obtained through solving optimization problems. Finally, the proposed approaches are compared by simulation studies of an automated highway system.     

System modeling and robust control of an AMB spindle : part II a robust controller design and its implementation

This paper discusses an entire procedure for a robust controller design and its implementation of an AMB (active magnetic bearing) spindle, which is part II of the papers presenting details of system modeling and robust control of an AMB spindle. Since there are various uncertainties in an AMB system and reliability is the most important factor for applications, robust control naturally gains attentions in this field. However, tight evaluations of various uncertainties based on experimental data and appropriate performance weightings for an AMB spindle are still ongoing research topics. In addition, there are few publications on experimental justification of a designed robust controller. In this paper, uncertainties for the AMB spindle are classified and described based on the measurement and identification results of part I, and an appropriate performance weighting scheme for the AMB spindle is developed. Then, a robust control is designed through the mixedμ synthesis based on the validated accurate nominal model of part I, and the robust controller is reduced considering its closed loop performance. The reduced robust controller is implemented and confirmed with measurements of closed-loop responses. The AMB spindle is operated up to 57,600 rpm and performance of the designed controller is compared with a benchmark PID controller through experiments. Experiments show that the robust controller offers higher stiffness and more efficient control of rigid modes than the benchmark PID controller.     

Dynamic characteristic analysis and lmi-basedh∞, controller design for a line of sight stabilization system

This paper is concerned with the design of an LMI (Linear Matrix Inequality)-basedH∞, controller for a line of sight (LOS) stabilization system and with its robustness performance. The linearization of the system is necessary to analyze various nonlinear characteristics, but the linearization entails modeling uncertainties which reduce its performance. In addition, the stability of the LOS can be adversely affected by angular velocity disturbances while the vehicle is moving. As the vehicle accelerates, all the factors that are ignored and simplified for the linearization tend to inhibit the performance of the system. The robustness in the face of these uncertainties needs to be assured. This paper employsH∞ control theory to address these problems and the LMI method to provide a suitable controller with minimal constraints for the system. Even though the system matrix does not have a full rank, the proposed method makes it possible to design aH∞ controller and to deal withR and S matrices for reducing the system order. It can be also shown that the proposed robust controller has a better disturbance attenuation and tracking performance. The LMI method is also used to enhance the applicability of the proposed reduced-orderH∞ controller for the system given. The LMI-basedH∞ controller has superior disturbance attenuation and reference input tracking performance, compared with that of the conventional controller under real disturbances.     

A design of a robust discrete-time controller

In this paper, we proposed a robust discrete-time controller. This control system, which is derived from the idea of the normalized plant, does not include plant parameters. Thus, we obtain a control system independent of plant parameters and that has the same structure as a conventional optimal servo control system. Simulation and experimental results show that the proposed method is fairly robust to plant parameter variations and external disturbances.     

电梯远程监控系统中快速响应系统研究

讨论了电梯远程监控系统的一般组成及控制原理。把远程视频监控的功能集成到电梯的远程监控系统中，从预诊断到故障排除过程中贯穿快速响应思想，探讨了电梯远程监控系统的快速响应机制。在基于CAN总线电梯控制系统上开发了电梯远程监控系统，并进行了实验。     

Fuzzy controller design for passive continuous-time affine T–S fuzzy models with relaxed stability conditions

In order to design a fuzzy controller for complex nonlinear systems, the work of this paper deals with developing the relaxed stability conditions for continuous-time affine Takagi–Sugeno (T–S) fuzzy models. By applying the passivity theory and Lyapunov theory, the relaxed stability conditions are derived to guarantee the stability and passivity property of closed-loop systems. Based on these relaxed stability conditions, the synthesis of fuzzy controller design problem for passive continuous-time affine T–S fuzzy models can be easily solved via the Optimal Convex Programming Algorithm (OCPA) and Linear Matrix Inequality (LMI) technique. At last, a simulation example for the fuzzy control of a nonlinear synchronous generator system is presented to manifest the applications and effectiveness of proposed fuzzy controller design approach.     

Lyapunov theory based robust control of complicated nonlinear mechanical systems with uncertainty

This paper presents a robust control approach for nonlinear uncertain crane systems with a three DOF framework. We deal with an overhead crane in which a trolley located on the top is moved to x- and y-axes independently. We first approximate the nonlinear system model through feedback linearization transformation to simply construct a PD control and then design a robust control system for compensating control deviation feasibly occurring due to modeling error or system perturbation in practice. An adaptive control rule is analytically derived by using Lyapunov stability theory given bounds of system perturbation. We accomplish numerical simulation for evaluating the proposed methodology and demonstrate its superiority by comparing with the traditional control strategy. This paper was recommended for publication in revised form by Associate Editor Dong Hwan Kim Hyun Cheol Cho received a B.S. from the Pukyong National University in 1997, a M.S. from the Dong-A University, Korea in 1999, and a Ph.D. from University of Nevada-Reno, USA in 2006. He is currently a post-doc researcher in the Dept. of Electrical Engineering, Dong-A University. His research interests are in the areas of control systems, neural networks, stochastic process, and signal processing.     

Optimal design and development of electromagnetic linear actuator for mass flow controller

In this paper, we constructed the analytic model of control valve as a function of electric and geometric parameters, and analyzed the influence of the design parameters on the dynamic characteristics. For improving the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design aims to minimize the response time and maximize force efficiency. By this procedure, control valve can be designed to have fast response in motion.     

Optimised sensor selection for control and fault tolerance of electromagnetic suspension systems: A robust loop shaping approach

This paper presents a systematic design framework for selecting the sensors in an optimised manner, simultaneously satisfying a set of given complex system control requirements, i.e. optimum and robust performance as well as fault tolerant control for high integrity systems. It is worth noting that optimum sensor selection in control system design is often a non-trivial task. Among all candidate sensor sets, the algorithm explores and separately optimises system performance with all the feasible sensor sets in order to identify fallback options under single or multiple sensor faults. The proposed approach combines modern robust control design, fault tolerant control, multiobjective optimisation and Monte Carlo techniques. Without loss of generality, it's efficacy is tested on an electromagnetic suspension system via appropriate realistic simulations.     

Probabilistic robust stabilization of fractional order systems with interval uncertainty

This study investigates effects of fractional order perturbation on the robust stability of linear time invariant systems with interval uncertainty. For this propose, a probabilistic stability analysis method based on characteristic root region accommodation in the first Riemann sheet is developed for interval systems. Stability probability distribution is calculated with respect to value of fractional order. Thus, we can figure out the fractional order interval, which makes the system robust stable. Moreover, the dependence of robust stability on the fractional order perturbation is analyzed by calculating the order sensitivity of characteristic polynomials. This probabilistic approach is also used to develop a robust stabilization algorithm based on parametric perturbation strategy. We present numerical examples demonstrating utilization of stability probability distribution in robust stabilization problems of interval uncertain systems.     

An optimal PID controller via LQR for standard second order plus time delay systems

An improved tuning methodology of PID controller for standard second order plus time delay systems (SOPTD) is developed using the approach of Linear Quadratic Regulator (LQR) and pole placement technique to obtain the desired performance measures. The pole placement method together with LQR is ingeniously used for SOPTD systems where the time delay part is handled in the controller output equation instead of characteristic equation. The effectiveness of the proposed methodology has been demonstrated via simulation of stable open loop oscillatory, over damped, critical damped and unstable open loop systems. Results show improved closed loop time response over the existing LQR based PI/PID tuning methods with less control effort. The effect of non-dominant pole on the stability and robustness of the controller has also been discussed.     

一种变参数的控制图方法及其稳健分析

针对在实际应用中,现有的控制图仅仅对某个固定大小的偏移有效的问题,首先提出了一种变参数的控制图设计方法,并对这种控制图的平均运行长度的计算方法进行了探讨.然后讨论了变参数控制图的稳健设计方案,通过与常规控制图和EWMA图进行比较,说明提出的监控方法对过程中出现的不同程度的偏移都是有效的.     

On robust stability of linear time invariant fractional-order systems with real parametric uncertainties

In this paper, the robust bounded-input bounded-output stability of a large class of linear time invariant fractional order families of systems with real parametric uncertainties is analyzed. The transfer functions contain polynomials in fractional powers of the Laplace variable s, possibly in combination with exponentials of fractional powers of s. Using the concept of the value set and a generalization of the zero exclusion condition theorem, a theorem to check the robust bounded-input bounded-output stability of these families of systems is presented. An upper cutoff frequency for drawing the value sets is provided as well. Finally, two numerical examples are given to illustrate results obtained by the lemma and theorems presented in the paper.     

Analysis of robust stability and performance for two-degree of freedom control structure with dynamic controller

In the two-degree of freedom control, the performance of good command following and disturbance rejection are considered separately. Qualitatively, good performance is equivalent to minimizing the energy of the error for any inputs. In this work, usingH _∞-formulation in the frequency domain, robust stability and robust performance specifications have been analyzed for the two-degree of freedom control structure with a dynamic controller. When the two-degree of freedom system having a feed-forward loop is controlled by a dynamic controller, two different performance weight functions are imposed and the robust performance specification is proposed in terms of the return ratio and feed-forward loop. The design algorithm in the frequency domain is illustrated for the simplified retail model of Industrial Dynamics to compare three kinds of control laws, which are the output feedback control scheme and two additional dynamic control ones. Numerical simulation results show that the dynamic control laws provide a larger robust stability margin than the output feeback control one and has good performance robustness for disturbance rejection at low frequencies.     

并联机器人轨迹跟踪离散变结构鲁棒控制器设计

本文根据并联机器人支撑杆教学模型参数摄动较大和时变的特点,设计了一种用于并联机器人轨迹跟踪的离散滑模变结构鲁棒控制器,通过引入变速趋近律,控制系统响应速度快,对参数摄动和外界干扰具有较强的鲁棒性,仿真研究结果表明,本文的控制方案能实现较高精度的快速轨迹跟踪,同时可削弱或避免通常变结构控制中不可避免的抖振。     

Non-fragile sampled-data robust synchronization of uncertain delayed chaotic Lurie systems with randomly occurring controller gain fluctuation

This paper proposes a new non-fragile stochastic control method to investigate the robust sampled-data synchronization problem for uncertain chaotic Lurie systems (CLSs) with time-varying delays. The controller gain fluctuation and time-varying uncertain parameters are supposed to be random and satisfy certain Bernoulli distributed white noise sequences. Moreover, by choosing an appropriate Lyapunov-Krasovskii functional (LKF), which takes full advantage of the available information about the actual sampling pattern and the nonlinear condition, a novel synchronization criterion is developed for analyzing the corresponding synchronization error system. Furthermore, based on the most powerful free-matrix-based integral inequality (FMBII), the desired non-fragile sampled-data estimator controller is obtained in terms of the solution of linear matrix inequalities. Finally, three numerical simulation examples of Chua's circuit and neural network are provided to show the effectiveness and superiorities of the proposed theoretical results.