Optimal Linear Preview Control of Active Vehicle Suspension

The problem of linear preview control of vehicle suspension is considered as a continuous time stochastic optimal control problem. In the proposed approach minimal a priori information about the road irregularities is assumed and measurement errors are taken into account. It is shown that estimation and control issues can be decoupled. The problem formulation and the analytical solution are given in a general form and hence they apply to other problems in which the system disturbances are unknown a priori, even in a stochastic sense, but some preview information is possible.

The solution is applied to a two-degree-of-freedom (2-DOF) vehicle model. The effects of preview information on ride comfort, road holding, working space of the suspension and power requirements are examined in time and frequency domains. The results show that the greatest potential is for improving road holding properties. This effect could not have been observed in previous studies based on a 1-DOF vehicle model. It is also demonstrated that the presence of preview drastically reduces power requirements, thus relieving the performance versus actuator power dilemma.     

Preview Control Algorithms for the Active Suspension of an Off-Road Vehicle

The potential performance improvement using preview control for active vehicle suspension was first recognized in the late nineteen sixties. All work done since that time has been based on optimal control theory using simple vehicle models.

In this article, the performance of quarter vehicle preview controllers when applied to a real off-road vehicle is simulated using both two degree of freedom quarter and ten degree of freedom full vehicle models. The results, which are compared with non-preview active and conventional passive suspensions, confirm that preview control reduces vertical acceleration of the body centre of gravity, which results in improved ride quality. Further, reductions in pitch and roll motion result from smaller vertical displacements of the vehicle quarters. Coupling between quarters, through the vehicle body, appears to have a smoothing effect on the control.

As an alternative to optimal control theory based controllers, a simple ad hoc preview controller based on isolating the vehicle body from dynamic loads transmitted through the suspension is proposed. Simulation results show that such a controller outperforms the optimal control theory based controllers over small discrete disturbances but responds poorly to disturbances encountered from other than steady state.     

Performance Index for a Preview Active Suspension Applied to a Quarter-Car Model

A simple and convenient matrix expression is derived for the performance index in the case of a linear vehicle model with two degrees of freedom and a preview active suspension, subject to a unit step road input and employing optimal control. The usual quadratic integral-type performance index is assumed and the effect of an additional form of constraint is described briefly. The effects of preview time on the performance index and the optimal feed-forward control are illustrated graphically for a particular example.     

Performance Index for a Preview Active Suspension Applied to a Quarter-Car Model

A simple and convenient matrix expression is derived for the performance index in the case of a linear vehicle model with two degrees of freedom and a preview active suspension, subject to a unit step road input and employing optimal control. The usual quadratic integral-type performance index is assumed and the effect of an additional form of constraint is described briefly. The effects of preview time on the performance index and the optimal feed-forward control are illustrated graphically for a particular example.     

基于预测控制和频率成型性能指标的主动悬架控制策略研究

预测控制（包括轴距时间延迟）具有改善系统动态性能的能力,对性能指标的频率成型则可以改善乘坐舒适性。结合以上两种方法,提出了一种算法用于主动悬架控制策略的设计,并在时域和频域利用此算法对一个五自由度主动悬架车辆模型进行仿真,检验了算法的可行性和控制效果。     

汽车主动悬架与电动助力转向系统多目标优化及集成控制

建立了整车主动悬架和电动助力转向系统动力学模型,构建线性控制的主动悬架和PD控制的电动助力转向系统集成控制器,应用遗传算法对集成控制系统的结构参数和控制参数进行多目标优化。结果表明,经过多目标优化后的集成控制系统,既可保证车辆操纵轻便性,又显著提高了整车操纵稳定性、安全性和行驶平顺性。     

汽车半车主动悬架的最优控制研究

本文运用车辆动力学理论,建立了半车四自由度主动悬架系统的动力学模型。同时依据最优控制理论设计了主动悬架最优控制器并进行了Matlb+simulink仿真。研究结果表明采用最优控制的主动悬架比被动悬架具有更好的平顺性。     

车辆主动悬架系统的LMS自适应控制

选择LMS自适应滤波算法,通过调整自适应滤波器的权系数使二次性能指标达最小,根据单个样本方差的负梯度来调节权系数;得到控制输出。针对简化的车辆模型,将空钩控制、广义自适应控制与LMS自适应控制相对比。仿真计算表明,主动悬架系统LMS自适应控制策略不仅计算简单,而且理论上在主动悬架系统中的应用是切实可行的,性能明显优于其它对比控制方法。     

Optimization and Performance Enhancement of Active Suspensions for Automobiles under Preview of the Road

The problem of deriving control laws which minimize specified performance indices for a vehicle moving on a rough surface with preview of the surface elevation is considered. The approach is based on linear optimal tracking theory and consequently the system elements are taken to be linear and the performance index is constrained to be of quadratic form.

The ideas of overtaking optimality are applied to the problem in order to achieve a closed form solution for the control. Then, using the control laws derived, computer simulations of performance are conducted and time histories are shown. In the absence of limitations on either processing or actuator speeds, and for cases in which the preview is sufficient to give good control laws, the value of the preview in enhancing vehicle suspension performance is assessed. Comparisons are made with results in the literature.     

主动悬架系统对汽车制动性能改善分析

针对汽车制动过程中质量转移而使最大制动力下降的问题，提出利用主动悬架系统减小汽车动态车轮载荷的方法。通过模拟分析得到，利用主动悬架系统可以有效降低汽车由于质量转移而引起车轮动态轴荷的改变量，限制了汽车最大制动力的下降，是解决制动力下降的一个比较有效的方法。     

汽车主动悬架最优控制：采用频域计权形式性能指标函数

本文从提高汽车的乘坐舒适性角度出发，研究了主动悬架的最优控制问题。根据坐位人体的振动响应特性构造了频域计权形式二交型性能指标函数。     

采用电磁直线电机的主动悬架控制系统的设计与能量分析

针对因特殊的动力布置形式导致的轮边驱动电动汽车操稳性和平顺性之间冲突,本文中提出了一种新式电磁直线电机式悬架系统的主动控制系统。考虑到其能量回收性能不佳的弊端,基于LQR控制设计了一种包含能量管理单元的能量回收控制器,并在Matlab/Simulink中对整个系统进行了仿真。结果表明,所设计的能量回收控制器不仅能够改善汽车的操稳性和平顺性,而且能有效回收汽车悬架的振动能量。     

汽车悬架控制臂的拓扑优化与性能计算

建立了含有球铰和衬套的汽车悬架控制臂优化设计模型,利用拓扑优化技术对悬架控制臂进行了优化设计.论述了对控制臂拓扑优化时,其优化空间的确定和载荷工况的确定方法.根据优化结果,设计了控制臂.对该控制臂的应力、固有频率和刚度进行了计算.结果表明,建立的控制臂优化模型较真实地描述了控制臂的工作特性,优化结果更符合实际情况.     

基于11自由度列车车辆模型的主动悬挂预见控制研究

讨论了预见控制在列车车辆主动悬挂系统中的应用，分析了预见控制的设计方法，指出如何利用未来信息，在一个11个自由度的列车车辆模型的基础上对预见控制进行仿真研究，结果表明预见控制具有良好的控制效果。     

最小均方自适应控制汽车主动悬架的仿真

根据汽车行驶平顺性和操纵稳定性的评价方法，确定簧上质量的加速度、车轮与地面间的动载荷以及簧上、簧下质量的动挠度为评价指标。选择LMS自适应滤波算法，通过调整自适应滤波器的权系数使二次性能指标达最小。针对简化的车辆模型，经过大量的仿真计算，确定主动悬架系统LMS自适应控制策略不仅计算简单，而且3项评价指标均得到显著的降低。结果分析表明，LMS自适应控制策略理论上在主动悬架系统中的应用是切实可行的。     

主动悬架用直线作动器结构设计及性能分析

针对现有主动悬架作动器存在能耗大、功率密度低等不足,设计了一款电磁力大而波动小的永磁直线作动器。运用基于圆柱坐标标量磁位的分离变量法对作动器气隙径向磁场进行解析,验证了所建的有限元模型。研究作动器电磁力及其波动特性,并用波动比评价其波动特性。结果显示:电磁力与输入电压和运行速度有密切关系;电磁力的波动随电磁力上升而增大,但波动比降低并逐渐稳定于6.8%左右。通过作动器电磁力计算并和被动减振器阻尼力测试值进行对比,表明所设计的的电磁作动器能够满足悬架对阻尼力的要求。     

汽车悬架控制系统发展概述

分析了汽车悬架主动/半主动控制的基本原理,从控制策略、执行机构以及应用情况三方面对汽车悬架控制系统的发展状况作了分析、总结及趋势预测,为今后汽车悬架控制系统的发展方向提出了建议。     

主动悬架系统对汽车加速性能改善分析

针对前轴驱动汽车加速过程中质量转移而使最大驱动力下降的问题，提出了利用主动悬架系统减小汽车车轮动态载荷对其进行改善的方法，并进行了控制系统的设计。模拟分析表明，利用主动悬架系统可以有效地降低前轴驱动汽车由于质量转移而引起的车轮动载荷的改变，是解决加速过程中驱动力下降的一个比较有效的方法。     

Mechanical and Control Design of a Variable Geometry Active Suspension System

In this study, a variable geometry active suspension system is considered. Actuation is employed to vary the leverage ratio between spring/damper unit and road wheel assembly. Since actuation is substantially perpendicular to the main suspension unit forces, work is primarily done only against frictional resistances to motion and the systems have inherently low force and energy requirements. Mechanical design and control system design involving proportional/differential elements or neural networks are discussed. System performance in self-levelling, free vibrations and manoeuvring of a theoretical vehicle are calculated. Good control of roll angle and jacking responses are predicted and energy economy is confirmed by these trials, which include a detailed consideration and modelling of the electrical actuators. The results reinforce the notion that variable geometry schemes have practical applications potential and are worthy of further research effort.     

Performance Potential and Power Consumption of Slow-Active Suspension Systems with Preview

Two possible layouts of a slow-active suspension model are analysed. Optimal control laws for different actuator bandwidths and various amounts of road preview are generated, and estimates of power consumption are made. Higher bandwidth systems (10Hz) require less preview to obtain a given level of performance than those with a lower bandwidth (3Hz) but use more energy in doing so. Similar performance is available from the two systems considered, although the second uses considerably less energy to obtain that performance.