A unified framework for the study of anti-windup designs

We present a unified framework for the study of linear time-invariant (LTI) systems subject to control input nonlinearities. The framework is based on the following two-step design paradigm: ‘design the linear controller ignoring control input nonlinearities and then add anti-windup bumpless transfer (AWBT) compensation to minimize the adverse effects of any control input nonlinearities on closed loop performance’. The resulting AWBT compensation is applicable to multivariable controllers of arbitrary structure and order. All known LTI anti-windup and/or bumpless transfer compensation schemes are shown to be special cases of this framework. This unification of existing schemes for AWBT compensation under a general framework is the main result of the paper.     

Studies on improving vehicle handling and lane keeping performance of closed-loop driver–vehicle system with integrated chassis control

This study proposes a new integrated robust model matching chassis controller to improve vehicle handling performance and lane keep ability. The design framework of the H_∞ controller is based on linear matrix inequalities (LMIs), which integrates active rear wheel steering control, longitudinal force compensation and active yaw moment control. To comprehensively evaluate the performance of the integrated chassis control system, a closed-loop driver–vehicle system is used. The effectiveness of the integrated controller on handling performance improvement is tested by a vehicle without driver model under a crosswind disturbance. At the same time, both the handling and lane keeping improving performance of the closed-loop driver–vehicle system is evaluated by tracking an S shape winding road. The simulation results reveal that the integrated chassis controller not only achieves preferable handling performance and stability, but also improves the vehicle lane keep ability significantly, and can alleviate the working load of the driver.     

Large angle attitude control of spacecraft with actuator saturation

This paper presents spacecraft large angle attitude control problem with actuator saturation limit. Traditional approach for control design for the spacecraft large angle maneuver is a fixed gain proportional plus integral plus derivative (PID) controller using quaternion attitude variables with stability guarantee. Unwanted external disturbance inputs may induce excessively large error by the PID control. Anti-windup control and intelligent integrator are effective in reducing the rapid build up of the control signal due to, in particular, integral control action. Application of the anti-windup and intelligent integrator which already have been studied extensively in other areas is made to the large angle feedback controller minimizing reaction wheel type actuator saturation. Conventional PID controller is modified by augmenting additional control actions for the purpose of performance improvement.     

Decentralized adaptive predictive control of multireach irrigation canal

This paper presents the design of a predictive controller for decentralized control of an irrigation canal. The overall canal is decomposed into N subsystems (reaches) separated by a control structure (gate). The subsystems are interdependent because flow through the structures depends on both up- and downstream water levels. Here, predictive control theory is used to formulate a set of local controllers for the automatic operation of each reach gate. The control scheme presented explicitly takes into account the interactions among subsystems. The objective of each controller is to maintain the downstream end water level of each reach at a constant target value under external perturbation. To evaluate the controller performance in realistic conditions, it is tested on an open-canal flow non-linear model. The case study considered deals with eight canal reaches.     

Anti‐windup synthesis for nonlinear dynamic inversion control schemes

A general anti‐windup (AW) compensation scheme is provided for a class of input constrained feedback‐linearizable nonlinear systems. The controller considered is an inner‐loop nonlinear dynamic inversion controller, augmented with an outer‐loop linear controller, of arbitrary structure. For open‐loop globally exponentially stable plants, it is shown that (i) there always exists a globally stabilizing AW compensator corresponding to a nonlinear generalization of the Internal‐Model‐Control (IMC) AW solution; (ii) important operator theoretic parallels exist between the AW design scheme for linear control and the suggested AW design scheme for nonlinear affine plants and (iii) a more attractive AW compensator may be obtained by using a nonlinear state‐feedback term, which plays a role similar to the linear state‐feedback term in linear coprime factor‐based AW compensation. The results are demonstrated on a dual‐tank simulation example. Copyright © 2009 John Wiley & Sons, Ltd.     

An Improved Anti‐Windup Bumpless Transfer Structures Design for Controllers Switching

In this paper, an anti‐windup bumpless transfer (AWBT) control structure combined with linear interpolation method is proposed for smooth switching control. By choosing an appropriate scheduling signal, different controllers can be switched smoothly under a unified framework. Meanwhile, some robust specifications including H₂/H_∞ performance, pole placement constraint, and passivity of the closed‐loop system can be preserved through controller switching. Furthermore, for the linear system subject to input saturation, the stability and L₂ gain of the closed‐loop system can be guaranteed. Finally, a cart‐spring pendulum system is simulated to demonstrate the effectiveness of the proposed scheme.     

Robust control design for precision positioning of a generic piezoelectric system with consideration of microscopic hysteresis effects

This study performs precision positioning of a generic piezoelectric structure against hysteresis effects by finite elements, microscopic hysteresis cancellation and robust H _?? compensation. The designed control algorithm is expected to be effective in enhancing servo performance of hard disk drives. The precision positioning is accomplished by adding a polarization term into the linear constitutive equations of piezoelectric materials. This polarization term is then described by the well-known Preisach model. Applying basic principles of finite elements and Hamilton??s thoery, the macroscopic governing equations of an arbitrary piezoelectric system in finite elements are obtained. Based on the macro-model, a controller consisting of two parts is designed to perform the precision positioning of a generic piezo-structure. The first part is responsible for direct hysteresis cancellation at the microscopic level, while the second one is a robust H _?? controller to overcome inevitable cancellation errors. In this way, the control effort is then more effective than the conventional PI and double-lead controller without microscopic hysteresis cancellation. A simple piezoelectric structure of a bender-bimorph cantilever beam is considered for designs and experimental validation. Based on experimental results, the proposed control design is found effective to suppress hysteresis effects as opposed to conventional controllers.     

Robust flight control system design using H∞ loop-shaping and recessive trait crossover genetic algorithm

A proposed approach to robust controller design is introduced. This approach combines the recessive trait crossover genetic algorithm with the loop-shaping design procedure using H_∞ synthesis. The requirements, design and simulation of a flight control system for precision tracking task are considered. The proposed method is applied to design a control system for the F-16 fighter aircraft model. The flight simulations reveal that the desired performance objectives are achieved and that the controller provides acceptable performance in spite of modeling errors and plant parameter variations.     

RST controller design for a non-uniform multi-rate control system

In this work, a non-uniform multi-rate controller which includes an RST control stage is introduced. Due to several issues, in some systems the use of non-uniform (irregular) multi-rate sampling becomes inevitable. When using a uniform (regular) multi-rate controller in this kind of situations, control performance is usually degraded (if it is compared to that obtained in the nominal, uniform sampling context). Thus, the design of a non-uniform controller proper for this sampling scheme is needed to keep the performance. A sequence of different non-uniform sampling frames can be considered, and different controllers must be designed for each frame using appropriate methods. When switching among these controllers, stability problems can appear. So, the control system stability will be assured in terms of Linear Matrix Inequalities (LMIs). To achieve some advantages at the design step, the discrete-time input–output representation will be used. But, since the classical, uniform z^?i delay operator could not be able to represent non-uniform sampling situations, the so-called non-uniform operator will be required. Simulation results illustrate that this control proposal is able to keep control system performance and preserve stability.     

Direct adaptive interval type-2 fuzzy control of multivariable nonlinear systems

A fuzzy logic controller equipped with a training algorithm is developed such that the H^∞ tracking performance should be satisfied for a model-free nonlinear multiple-input multiple-output (MIMO) system, with external disturbances. Due to universal approximation theorem, fuzzy control provides nonlinear controller, i.e., fuzzy logic controllers, to perform the unknown nonlinear control actions and the tracking error, because of the matching error and external disturbance is attenuated to arbitrary desired level by using H^∞ tracking design technique. In this paper, a new direct adaptive interval type-2 fuzzy controller is developed to handle the training data corrupted by noise or rule uncertainties for nonlinear MIMO systems involving external disturbances. Therefore, linguistic fuzzy control rules can be directly incorporated into the controller and combine the H^∞ attenuation technique. Simulation results show that the interval type-2 fuzzy logic system can handle unpredicted internal disturbance, data uncertainties, very well, but the adaptive type-1 fuzzy controller must spend more control effort in order to deal with noisy training data. Furthermore, the adaptive interval type-2 fuzzy controller can perform successful control and guarantee the global stability of the resulting closed-loop system and the tracking performance can be achieved.     

Robust digital control approach for high performance tunneling current measurement system

This paper is devoted to the digital control system design for high performance measurement of tunneling current. A common approach for such applications is to use a conventional Proportional Integral (PI) control. In this paper, a robust digital design method is instead considered, based on combined pole placement with sensitivity function shaping, and allowing for better performance tuning in terms of precision, robustness and disturbance rejection. The resulting control scheme looks like some enhanced PID controller, and is validated over an experimental setup, developed in GIPSA-lab (Grenoble Image Parole Signal Automatique) research center. The corresponding simulation and experimental results show improved performances with respect to those obtained with the more conventional PI control technique.     

Simultaneous linear and anti-windup controller synthesis using multiobjective convex optimization

We present a method for the synthesis of a control law for input constrained linear systems that incorporates both a traditional linear output-feedback controller as well as a static anti-windup compensator. Unlike traditional two-step anti-windup controller designs in which the linear controller and anti-windup compensator are designed sequentially, our method synthesizes all controller parameters simultaneously. This one-step design retains the anti-windup structure, thus providing structurally ‘a priori’ compensation for saturation. We derive sufficient conditions for guaranteeing global quadratic stability and for satisfying multiple, possibly conflicting, performance objectives on the constrained and unconstrained closed-loop dynamics. The resulting synthesis problem is recast as an optimization over linear matrix inequalities (LMIs). We demonstrate the proposed method on a benchmark problem.     

Adaptive CMAC neural control of chaotic systems with a PI-type learning algorithm

The cerebellar model articulation controller (CMAC) has the advantages such as fast learning property, good generalization capability and information storing ability. Based on these advantages, this paper proposes an adaptive CMAC neural control (ACNC) system with a PI-type learning algorithm and applies it to control the chaotic systems. The ACNC system is composed of an adaptive CMAC and a compensation controller. Adaptive CMAC is used to mimic an ideal controller and the compensation controller is designed to dispel the approximation error between adaptive CMAC and ideal controller. Based on the Lyapunov stability theorems, the designed ACNC feedback control system is guaranteed to be uniformly ultimately bounded. Finally, the ACNC system is applied to control two chaotic systems, a Genesio chaotic system and a Duffing–Holmes chaotic system. Simulation results verify that the proposed ACNC system with a PI-type learning algorithm can achieve better control performance than other control methods.     

基于鲁棒开环解耦的系统逆二自由度控制

针对MIMO系统的轨迹跟踪,提出一种基于鲁棒开环解耦的系统逆二自由度（2DOF）控制方法．该方法通过鲁棒开环解耦解决MIMO系统的耦合问题,利用系统逆2DOF控制保证轨迹跟踪性能．首先提出一种保证预补偿器阶数最小和解耦系统鲁棒性的鲁棒开环解耦方法;然后结合鲁棒开环解耦和系统逆2DOF控制,给出系统逆前馈控制和H∞混合灵敏度鲁棒反馈控制器的设计方法;最后通过设计实例及仿真结果验证了该控制方法的有效性．     

Nonlinear control of U-tube steam generators via H∞ control

The objective of this paper is to design, analyze and evaluate a controller for the water level of U-tube steam generators. The control objective is to closely regulate the water level during extreme load variations and despite drifts in process parameters. The controller design is based on the H_∞-norm. Gain-scheduling is used to obtain a global water-level controller. The controller performance is satisfactory at all power levels. In view of a comparative analysis of the H_∞ controller with an LQG/LTR controller, implementation and use of the gain-scheduled H_∞ controller over the equivalent LQG/LTR controller is recommended.     

基于ARM的网络远程闭环控制机理研究与实现

针对网络远程控制的研究大部分还只是停留在开环控制或工业专用网络的问题,本文提出了一种基于Internet的远程闭环控制方案,根据该方案设计并实现了一个基于Internet的ARM网络远程控制器和本地控制器,在实验室搭建了网络远程闭环控制物理模拟实验平台,并在该平台上,针对大惯性水位控制对象和网络传输延时的不确定性问题,设计了一种基于在线信息排队的网络延时补偿方法,该方法克服了网络拥塞与不确定性延时对系统的影响,进行了网络远程闭环实时控制实验,得到了较好的控制效果。     

Hierarchical neuro-fuzzy current control for a shunt active power filter

This paper presents the design of a hierarchical neuro-fuzzy current control scheme for a shunt active power filter compared with a single fuzzy controller scheme. A single fuzzy controller scheme is presented first and an ANFIS based neuro-fuzzy controller is connected hierarchically to the first one to improve the performance. Simulation results show that harmonic compensation is achieved with both schemes, however switching performance is superior for hierarchical scheme. The method of switching controller development in this paper is new and can be applied to other power electronic converter applications for improved performance.     

Intelligent adaptive control for MIMO uncertain nonlinear systems

This paper investigates an intelligent adaptive control system for multiple-input–multiple-output (MIMO) uncertain nonlinear systems. This control system is comprised of a recurrent-cerebellar-model-articulation-controller (RCMAC) and an auxiliary compensation controller. RCMAC is utilized to approximate a perfect controller, and the parameters of RCMAC are on-line tuned by the derived adaptive laws based on a Lyapunov function. The auxiliary compensation controller is designed to suppress the influence of residual approximation error between the perfect controller and RCMAC. Finally, two MIMO uncertain nonlinear systems, a mass–spring–damper mechanical system and a Chua’s chaotic circuit, are performed to verify the effectiveness of the proposed control scheme. The simulation results confirm that the proposed intelligent adaptive control system can achieve favorable tracking performance with desired robustness.