A new semi-active suspension control strategy through mixed H_2/H_∞ robust technique

A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.

Mixed Gl2／GH2 multi-channel multi-objective control synthesis for discrete time systems

This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalized l2 (Gl2) and generalized H2 (GH2) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables. Consequently, the multi-channel multi-objective mixed Gl2/GH2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper.

Mixed H_2/H_∞ State Feedback Attitude Control of Microsatellite Based on Extended LMI Method

For the appearance of the additive perturbation of controller gain when the controller parameter has minute adjustment at the initial running stage of system,to avoid the adverse effects,this paper investigates the mixed H_2/H_∞ state feedback attitude control problem of microsatellite based on extended LMI method.Firstly,the microsatellite attitude control system is established and transformed into corresponding state space form.Then,without the equivalence restriction of the two Lyapunov variables of H_2 and H∞performance,this paper introduces additional variables to design the mixed H_2/H_∞ control method based on LMI which can also reduce the conservatives.Finally,numerical simulations are analyzed to show that the proposed method can make the satellite stable within 20 s whether there is additive perturbation of the controller gain or not.The comparative analysis of the simulation results between extended LMI method and traditional LMI method also demonstrates the effectiveness and feasibility of the proposed method in this paper.

Designing mixed <i>H</i>₂/<i>H</i>_&infin;structure specified controllers using Particle Swarm Optimization (PSO) algorithm

This paper proposes an efficient method for designing accurate structure-specified mixed H2/H∞ optimal controllers for systems with uncertainties and disturbance using particle swarm (PSO) algorithm. It is designed to find a suitable controller that minimizes the performance index of error signal subject to an unequal constraint on the norm of the closed-loop system. Although the mixed H2/H∞ for the output feedback approach control is considered as a robust and optimal control technique, the design process normally comes up with a complex and non-convex optimization problem, which is difficult to solve by the conventional optimization methods. The PSO can efficiently solve design problems of multi-input-multi-output (MIMO) optimal control systems, which is very suitable for practical engineering designs. It is used to search for parameters of a structure-specified controller, which satisfies mixed performance index. The simulation and experimental results show high feasibility, robustness and practical value compared with the conventional proportional-integral-derivative (PID) and proportional-Integral (PI) controller, and the proposed algorithm is also more efficient compared with the genetic algorithm (GA).

LMI Approach to Robust H_∞/H_2 Controller Design with Regional Poles Constraint of a Pump-Motor System

The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality （LMI）. These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.

Robust H_2 estimation and control

This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncertain system in terms of linear matrix inequalities (LMIs). A solution to the robust H2 estimation problem is then derived in terms of two LMIs. As compared to the existing results, our result on robust H2 estimation is more general. In addition, explicit search of appropriate scaling parameters is not needed as the optimization is convex in the scaling parameters. The LMI approach is also extended to solve the robust H2 control problem which has been difficult for the traditional Riccati equation approach since no separation principle has been known for uncertain systems. The design approach is demonstrated through a simple example.

On the Dual of a Mixed H_2/l_1 Optimisation Problem

The general discrete-time Single-Input Single-Output （SISO） mixed H2/l1 control problem is considered in this paper. It is found that the existing results of duality theory cannot be directly applied to this infinite dimension optimisation problem. By means of two finite dimension approximate problems, to which duality theory can be applied, the dual of the mixed H2/l1 control problem is verified to be the limit of the duals of these two approximate problems.

Robust H_∞ and H_2 Static Output Feedback Control of Discrete-time Piecewise Affine Singular Systems with Norm-bounded Uncertainties

This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncertainties. Based on a piecewise singular Lyapunov function combined with S-procedure,Projection lemma and some matrix inequality convexifying techniques,sufficient conditions in terms of linear matrix inequalities are given for the existence of an output-feedback controller for the discrete-time piecewiseaffine singular systems with a prescribed H∞disturbance attenuation level,and the H2norm is smaller than a given positive number. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. The numerical examples are given to illustrate the effectiveness of the proposed design methods.

Mixed L_1/H-infinity control for uncertain linear singular systems

The mixed L1/H-infinity control problem for a class of uncertain linear singular systems is considered using a matrix inequality approach. The purpose is to design a state feedback control law such that the resultant closed-loop system is regular, impulse-free, stable and satisfies some given mixed L1/H-infinity performance. A sufficient condition for the existence of such control law is given in terms of a set of matrix inequalities by the introduction of inescapable set and ＊-norm. When these matrix inequalities are feasible, an explicit expression of the desired state feedback control law is given. A numerical example is used to demonstrate the applicability of the proposed approach.

Robust <i>H</i>_∞Controller for High Precision Positioning System, Design, Analysis, and Implementation

In this paper, a systematic robust control design and analysis for a single axis precise positioner is presented. The effects of uncertainties on closed-loop stability and performance are considered in the H∞ robust controllers design. v-gap metric is utilized to validate the intelligently estimated uncertainty. The robust controllers are formulated within the frame- work of the standard H∞ mixed sensitivity optimization problem. Furthermore, a specially designed integral-H∞ and two-degree-of-freedom 2 DOF H∞ controllers are developed to provide improved robust performance and resolution properties. It is shown that the proposed design schemes are very effective for robust control and precise tracking performance of the servo positioning system.

Soft initial-rotation and H_∞ robust constant rotational speed control for rotational MEMS gyro

A novel soft initiai-rotation control system and an H∞ robust constant rotational speed controller （RCRSC） for a rotational MEMS （micro-electro-mechanical system） gyro are presented. The soft initial-rotation control system can prevent the possible tumbling down of the suspended rotor and ensure a smooth and fast initial-rotation process. After the initial-rotation process, in order to maintain the rotational speed accurately constant, the RCRSC is acquired through the mixed sensitivity design approach. Simulation results show that the actuation voltage disturbances from the internal carrier waves in the gyro is reduced by more than 15.3 dB, and the speed fluctuations due to typical external vibrations ranging from 10 Hz to 200 Hz can also be restricted to 10^-3 rad/s order.

汽车四轮转向系统的H_2/H_∞混合控制

为使汽车四轮转向系统具有良好的鲁棒性和干扰抑制性能 ,针对外界干扰 ,对汽车四轮转向系统模型进行了分析 ,并将其转化为H2 /H∞ 控制问题 ,运用Matlab的LMI控制工具箱设计了H2 /H∞ 混合最优控制器。仿真结果表明 ,设计的最优控制器具有良好控制效果。

H_2和H_∞主动悬架统一的理论框架与比较

以 2自由度 1/ 4车模型为例在鲁棒控制理论的统一框架下讨论H2 和H∞ 主动悬架的设计 ,并采用结构奇异值法和加权最坏RMS增益法对其鲁棒性能进行分析和比较。

差分进化改进微电网负荷频率混合H2/H∞鲁棒控制

针对外部扰动及系统参数摄动引起微电网负荷频率波动问题,设计了混合H2/H∞鲁棒控制器对系统负荷频率进行控制。建立了包含电池的柴油发电机组二次频率控制模型,引入低通滤波器,使电池对系统高频扰动信号具有较好的抑制能力。以误差平方的积分最小作为系统的目标函数,在综合H_2范数表征的系统性能和H∞范数表征的鲁棒性能下,设计具有多目标约束条件的混合H2/H∞鲁棒控制器。采用差分进化算法对控制器加权函数参数进行寻优,使控制器在满足约束条件下达到最优。仿真实验结果表明所提出方法在满足系统鲁棒性能的基础上,同时具备较好的控制输出,保证微电网频率在外部功率扰动和系统参数摄动情况下具有较好的动态性能。

混合H_2/H_∞鲁棒控制在飞行控制中的应用

利用混合 H2 / H∞ 鲁棒控制技术 ,研究飞机纵向控制系统的综合问题。针对飞机控制系统含有大量的非线性和不确定因素 ,用混合 H2 / H∞ 鲁棒控制方法设计线性状态反馈控制器 ,使飞机控制系统在鲁棒稳定条件下 ,满足一定的性能指标。在国产某飞机纵向控制系统中的应用表明 ,所提出的方法是实用的和有效的。

不确定系统混合H_2/H_∞鲁棒控制的直接迭代LMI方法

设计多胞型不确定系统的控制器时,引入附加变量能够减小设计保守性,但这会使线性矩阵不等式(LMI)的维数大大增加,控制器难以求解.本文阐述了一种基于直接迭代线性矩阵不等式(DILMI)方法的混合H2/H∞鲁棒控制方法.首先借助于仿射二次稳定理论将整个多胞型不确定集合的稳定性问题转化为该集合各顶点的稳定性问题.利用参数依赖Lyapunov方法,给出了一个保证系统鲁棒稳定,并满足混合H2/H∞性能指标的充分条件.随后采用DILMI算法实现了Lyapunov变量和控制增益的解耦,无需引入附加变量就能够求解充分条件中的非凸优化问题.最后,关于F-16多胞型模型的飞行仿真验证了该方法的有效性.

H_2/H_∞混合优化问题综述

H2 /H∞ 混合优化设计方法由于其可以使系统同时获得较好的鲁棒稳定性和鲁棒性能 ,一经提出 ,立即受到研究者的广泛关注 .本文综述了 H2 /H∞ 混合优化方法的产生、发展及其特点 ,概要介绍了 H2 /H∞ 优化理论研究的最新进展及实践应用的主要结果 ,分析了 H2 /H∞ 混合优化理论在理论和实际应用中的发展方向 .

不确定广义系统的鲁棒H_2控制

利用线性矩阵不等式 (LMI)方法 ,研究范数有界的不确定广义系统的鲁棒H2 性能分析与控制问题。对该系统所有容许的不确定参数 ,提出了满足鲁棒H2 次优性能的一个线性矩阵不等式 (LMI)的充分条件。进而设计了一个状态反馈控制律 ,保证了闭环系统是容许的且满足鲁棒H2 次优性能 ,即闭环传递函数的H2 范数小于一个给定的正数。利用Matlab控制工具箱 ,给出了该控制律的LMI实用设计方法。

建筑结构振动主动控制的H_2/H_∞混合凸优化方案

在地震信号和建筑结构系统的范数分析基础上,使用了混合控制优化指标J作为优化目标,并给出其物理含义·针对H2控制方案和H∞控制方案的优缺点,通过LMI凸优化方法求解混合控制器,给出了在给定γ值的前提下极小化指标J的H2/H∞混合控制方案,并给出了仿真算例·

基于多步控制策略的混合H_2/H_∞鲁棒预测控制器设计

针对具有外界扰动的线性定常(Linear time invariant,LTI)系统,本文研究了其鲁棒预测控制器(Robust model predictive control,RMPC)的设计方法.设计采用了混合的H2/H∞控制方法以有效地兼顾系统的抗干扰能力和闭环控制性能.同时,为了降低设计的保守性,设计利用闭环多步控制策略以扩大控制器的可行范围,改善系统控制性能.进而,为了便于实际实施,提出该RMPC的简化设计,通过将大部分在线计算量离线完成以降低鲁棒预测控制器的在线计算量.