一种变形的回路成形控制器及其应用

给出一种变形的回路成形控制器,并从理论上分析了将常规的回路成形控制器变形后能够改善系统动态性能所需的条件。将其应用船舶自动舵的设计,获得了满意的控制结果。     

Performance improvement of saturated system using loop shaping approach

Actuator saturation is an important issue when designing practical control systems. It usually induces the windup phenomenon and even yields system instability. In this paper, a two‐stage controller design method is proposed for systems with actuator limitations using the loop shaping approach. In this approach, a pre‐designed controller is first used to stabilize the control system to achieve the desired performance. A loop‐shaping‐based auxiliary controller is then introduced to reduce the windup effect, which might be caused by actuator limitation or functional damage during the mission. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

A loop-shaping design procedure using H∞ synthesis

A design procedure is introduced which incorporates loop shaping methods to obtain performance/robust stability tradeoffs, and a particular H_∞ optimization problem to guarantee closed-loop stability and a level of robust stability at all frequencies. Theoretical justification of this technique is given, and the effect of loop shaping on closed-loop behavior is examined. The procedure is illustrated in a controller design for a flexible space platform     

Covariance matrix adaptation evolution strategy based design of fixed structure robust H∞ loop shaping controller

This paper proposes the application of Covariance Matrix Adaptation Evolution Strategy (CMA-ES) in fixed structure H_∞ loop shaping controller design. Integral Time Absolute Error (ITAE) performance requirement is incorporated as a constraint with an objective of maximization of stability margin in the fixed structure H_∞ loop shaping controller design problem. Pneumatic servo system, separating tower process and F18 fighter aircraft system are considered as test systems. The CMA-ES designed fixed structure H_∞ loop-shaping controller is compared with the traditional H_∞ loop shaping controller, non-smooth optimization and Heuristic Kalman Algorithm (HKA) based fixed structure H_∞ loop shaping controllers in terms of stability margin. 20% perturbation in the nominal plant is used to validate the robustness of the CMA-ES designed H_∞ loop shaping controller. The effect of Finite Word Length (FWL) is considered to show the implementation difficulties of controller in digital processors. Simulation results demonstrated that CMA-ES based fixed structure H_∞ loop shaping controller is suitable for real time implementation with good robust stability and performance.     

基于混合灵敏度算法的电动转向控制系统研究*

建立电动助力转向系统的动力学模型并设计出EPS控制框图。根据该系统特性,选择基于H∞混合灵敏度的控制方法。在对S/T奇异值曲线的深入观察和研究的基础上,提出一种根据系统频域关键参数先构造闭环函数然后反推出系统控制器的方法。EPS系统频谱分析及路面干扰仿真结果表明,该方法设计的控制器简单有效,具有很好的鲁棒性能和鲁棒稳定性。     

An improved parallel cascade control structure for processes with time delay

Parallel cascade control strategies, to improve the dynamic performance of a control system, have been proposed earlier mainly for control of stable processes. In this paper, further results are presented for a new parallel cascade control structure and controller design for controlling stable, unstable or integrating processes with time delay. The design of the disturbance rejection controllers and the setpoint filter are based on loop shaping and ISE performance measures, respectively. A modified Smith predictor scheme is used in the primary loop to enhance the closed-loop performance of the system. The stabilization, robustness and performances of time delay processes are analyzed. The disturbance rejection capability of the proposed scheme is superior as compared to some existing methods. Examples are given to illustrate the usefulness of the proposed method and its superiority over some parallel cascade control schemes.     

连续搅拌反应釜过程的闭环增益成形PID控制器设计

针对连续搅拌反应釜（CSTR）系统控制问题,设计了一种基于闭环增益成形算法的PID控制器,以提高PID控制器设计的简洁性和鲁棒性。首先假设期望闭环回路传递函数有一阶形式,同时将受控对象的一阶传递函数和PID控制器构成实际闭环回路传递函数。然后,比较期望闭环回路传递函数和实际闭环回路传递函数,即可确定PID参数。最后,以某CSTR系统为例,利用该方法设计了PID控制器,并通过仿真结果比较,检验了该方法所得PID控制器的良好鲁棒稳定性和动态品质。     

Robust inverse optimal control laws for nonlinear systems

This work proposes a robust inverse optimal controller design for a class of nonlinear systems with bounded, time‐varying uncertain variables. The basic idea is that of re‐shaping the scalar nonlinear gain of an L_gV controller, based on Sontag's formula, so as to guarantee certain uncertainty attenuation properties in the closed‐loop system. The proposed gain re‐shaping is shown to yield a control law that enforces global boundedness of the closed‐loop trajectories, robust asymptotic output tracking with an arbitrary degree of attenuation of the effect of uncertainty on the output, and inverse optimality with respect to a meaningful cost that penalizes the tracking error and the control action. The performance of the control law is illustrated through a simulation example and compared with other controller designs. Copyright © 2003 John Wiley & Sons, Ltd.     

FPGA-based sliding mode direct control of single phase PWM boost rectifier

In this paper, a Field Programmable Gate Array (FPGA) based controller for single phase PWM boost rectifier is presented. The control is made up of an internal current control loop and external DC-link voltage control loop. The internal control loop allows active shaping of the line current and is synthesized via sliding mode theory. The external control loop is based on a PI controller and allows imposing the shape of the DC-link voltage response. Experimental results carried out on a FPGA-based prototyping platform are presented and discussed in order to illustrate the efficiency of the developed FPGA-based controller.     

Fixed‐order robust H∞ control and control‐oriented uncertainty set shaping for systems with ellipsoidal parametric uncertainty

In this paper, sufficient conditions for robust output feedback controller design for systems with ellipsoidal parametric uncertainty are given in terms of solutions to a set of linear matrix inequalities. A polynomial method is employed to design a fixed‐order controller that assigns closed‐loop poles within a given region of the complex plane and that satisfies an H_∞ performance specification. The main feature of the proposed method is that it can be extended easily for control‐oriented uncertainty set shaping using a standard input design approach. Consequently, the results can be extended to joint robust control/input design procedure whose controller structure and performance specifications are translated into the requirements on the input signal spectrum used in system identification. This way, model uncertainty set can be tuned for the robust control design procedure. The simulation results show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

Position‐dependent disturbance rejection using spatial‐based adaptive feedback linearization repetitive control

In this paper, we propose a new design of spatial‐based repetitive control for a class of rotary motion systems operating at variable speeds. The open‐loop system in spatial domain is obtained by reformulating a nonlinear time‐invariant system with respect to angular displacement. A two‐degree‐of‐freedom control structure (comprising two control modules) is then proposed to robustly stabilize the open‐loop system and improve the tracking performance. The first control module applies adaptive feedback linearization with projected parametric update and concentrates on robust stabilization of the closed‐loop system. The second control module introduces a spatial‐based repetitive controller cascaded with a loop‐shaping filter, which not only further reduces the tracking error, but also improves parametric adaptation. The overall control system is robust to model uncertainties of the system and capable of rejecting position‐dependent disturbances under varying process speeds. Stability proof for the overall system is given. A design example with simulation is provided to demonstrate the applicability of the proposed design. Copyright © 2008 John Wiley & Sons, Ltd.     

小型弹用发动机建模及控制研究

为了有效对某型航空发动机进行控制,首先对其过渡态的各状态段的实验数据,基于系统辨识的理论,按照预处理、辨识、验证的步骤求取其传递函数;考虑到发动机过渡态状态变化大,故利用鲁棒性强、能克服对象参数变化的H∞控制方法来进行控制系统的设计,并引入前馈比例控制器对控制结构进行变形,以克服H∞回路成形控制超调量大的缺陷;仿真结果表明辨识数据与原始数据的拟合度能够达到82.99%,鲁棒控制器在发动机状态大范围变化时仍能拥有不错的控制效果,调节时间1秒左右。     

Robust stabilization of linear multivariable systems: relations to approximation

A simple feedback controller methodology is presented that allows for exact tracking of the sinusoidal input signals and rejection of the sinusoidal disturbances in a closed loop control system. The control method is motivated by a mathematical inequality that expresses the tracking and disturbance rejection requirements for a closed loop system. The exact tracking of the input command at a particular frequency requires an infinite loop gain for the system at the frequency of the in put command. A second order undamped transfer function is cascaded to each input channel to increase the loop transfer function gain at the frequency of the input command. A feedback controller is then designed via the LQG/LTR method to stabilize the system while the loop gain remains large at the frequency of the input. The method is experimentally verified on a single axis servo system and extended to multivariable systems.     

Acceleration feedback in a lithographic tool

Acceleration feedback increases the mass of a system as experienced by disturbance forces. A high bandwidth is required to avoid phase lag in the position control loop. This article splits the acceleration controller in a forward and backward path to create the original process behavior for the position controller, removing the high-bandwidth requirement. Digital controller effects, incorporation of plant dynamics, and implications for setpoint feedforward are discussed. The method is implemented in the stage of a lithographic scanner operating at nanometer accuracy in semiconductor manufacturing. It is shown that the low-frequent disturbance rejection is considerably improved without impacting higher-frequency performance.     

Nonlinear adaptive control using the Fourier integral and itsapplication to CSTR systems

This paper presents a new nonlinear adaptive tracking controller for a class of general time-variant nonlinear systems. The control system consists of an inner loop and an outer loop. The inner loop is a fuzzy sliding mode control that is used as the feedback controller to overcome random instant disturbances. The stability of the inner loop is designed by the sliding mode control method. The other loop is a Fourier integral-based control that is used as the feedforward controller to overcome the deterministic type of uncertain disturbance. The asymptotic convergence condition of the nonlinear adaptive control system is guaranteed by the Lyapunov direct method. The effectiveness of the proposed controller is illustrated by its application to composition control in a continuously stirred tank reactor system.     

一种简化的H∞控制混合灵敏度算法

受到回路成形思想的启发,通过对H∞控制的S／T混合灵敏度奇异值曲线的观察及基于S和T具有相关性的考虑给出一种简化的H∞控制混合灵敏度算法,该算法避免了权函数的选择而对系统进行闭环增益成形,其核心是确定闭环系统传递函数即T的最终希望的形状,不加任何权函数,直接设计出K.由于T和S的相关性,T的形状确定,S的形状也就确定了,从而保证了设计出的控制系统具有良好的鲁棒性和鲁棒稳定性。     

舵减摇控制系统的开环增益成形设计

针对船舶航向/舵减横摇控制系统的特点,提出了一种新的设计方案.对舵减横摇控制回路,基于开环增益成形的思想,通过指定闭环灵敏度函数的幅频特性形状,得到相应的舵减横摇控制器.在设计过程中不但考虑了对象的非最小相位特性,还分析了Bode积分定理对性能的约束条件,在系统的性能和控制输出之间进行了折衷,给出了一组优化设计结果.对航向控制回路,应用混合灵敏度问题设计了H∞航向控制器.设计指标是在保证船舶能很好的跟踪航向指令的前提下尽可能的减小艏摇控制回路和横摇控制回路之间的耦合作用.仿真结果表明,所设计的舵减摇控制系统满足性能要求,取得了较高的减摇率,而且横摇运动对航向的影响很小.通过对摄动后的对象进行仿真,进一步验证了系统具有很好的鲁棒性.     

Closed loop identification and control loop reconfiguration: an industrial case study

The results of a joint university–industry collaborative project for control loop reconfiguration using closed loop experimental data from a fuel gas pressure control system are described in this paper. The fuel gas pressure was being regulated using a butane stream. For economic reasons, it was necessary to switch control to the ethane stream. Previous attempts at effecting this changeover had proved unsuccessful. In this study, a powerful system identification technique namely Canonical Variate Analysis (CVA) was employed to obtain the empirical plant models. A PI controller was then designed using the direct synthesis method. Acceptable closed loop behavior was obtained with little online tuning.     

基于回路成形的鲁棒增益调度控制器设计

针对目前基于线性变参数系统的增益调度控制设计中存在的控制结构复杂性问题，提出一种基于回路成形的简单且易实现的增益调度控制结构.在此基础上，提出一个鲁棒增益调度控制设计方法.设计过程首先采用补偿器函数使得被控对象奇异值具有期望的形状，以保证被控对象的性能要求，然后利用小增益定理设计一个鲁棒控制器，得到具有良好性能的、结构简单的鲁棒增益调度控制器.最后针对一个化工过程，说明此方法的有效性.     

一类非线性多变量系统的多模型自适应控制

针对一类不确定的非线性多变量离散时间动态系统,提出了一种基于切换的多模型自适应控制方法.该控制方法的特点在于以下两个方面:首先,引入一个高阶差分算子使得非线性系统的非线性项的限制条件不再要求全局有界;其次,提出的控制方法由线性自适应控制器、神经网络非线性自适应控制器以及切换机构组成:线性控制器用来保证闭环系统的输入输出信号有界,神经网络非线性控制器用来改善闭环系统的性能,基于性能指标的切换机构在每一时刻选择性能指标较好的控制器对系统进行控制.理论分析和仿真实验说明了提出的多模型自适应控制方法的有效性.