Hierarchical Control of Ride Height System for Electronically Controlled Air Suspension Based on Variable Structure and Fuzzy Control Theory

The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension （ECAS） has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control （VSC） technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.

A Hybrid Approach to Modeling and Control of Vehicle Height for Electronically Controlled Air Suspension

The control problems associated with vehicle height adjustment of electronically controlled air suspension （ECAS） still pose theoretical challenges for researchers, which manifest themselves in the publications on this subject over the last years. This paper deals with modeling and control of a vehicle height adjustment system for ECAS, which is an example of a hybrid dynamical system due to the coexistence and coupling of continuous variables and discrete events. A mixed logical dynamical （MLD） modeling approach is chosen for capturing enough details of the vehicle height adjustment process. The hybrid dynamic model is constructed on the basis of some assumptions and piecewise linear approximation for components nonlinearities. Then, the on-off statuses of solenoid valves and the piecewise approximation process are described by propositional logic, and the hybrid system is transformed into the set of linear mixed-integer equalities and inequalities, denoted as MLD model, automatically by HYSDEL. Using this model, a hybrid model predictive controller （HMPC） is tuned based on online mixed-integer quadratic optimization （MIQP）. Two different scenarios are considered in the simulation, whose results verify the height adjustment effectiveness of the proposed approach. Explicit solutions of the controller are computed to control the vehicle height adjustment system in realtime using an offline multi-parametric programming technology （MPT）, thus convert the controller into an equivalent explicit piecewise affine form. Finally, bench experiments for vehicle height lifting, holding and lowering procedures are conducted, which demonstrate that the HMPC can adjust the vehicle height by controlling the on-off statuses of solenoid valves directly. This research proposes a new modeling and control method for vehicle height adjustment of ECAS, which leads to a closed-loop system with favorable dynamical properties.

Fuzzy Sliding Mode Control for the Vehicle Height and Leveling Adjustment System of an Electronic Air Suspension

The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.

基于人机交互系统的商用车ECAS故障诊断研究

为提升商用车的行驶安全性,本文基于触摸屏式新型人机交互系统,对商用车电控空气悬架(electronically controlled air suspension,ECAS)系统的故障诊断系统进行研究。针对ECAS故障诊断系统总体架构,提出了ECAS故障诊断及故障保护机制,阐述了典型ECAS故障实例的诊断策略,并采用Matlab/Simulink搭建了诊断策略模型和故障码生成模型。为验证本文所提出的故障诊断及故障保护机制的可行性与实用性,以ECAS系统中压力传感器为例,对模型进行仿真分析和硬件在环试验。试验结果表明,在典型压力传感器故障工况下,本文所提出的ECAS故障诊断及故障保护机制,能够准确检测出相应故障,正确输出一系列相关信号,并在人机交互系统上将诊断结果进行实时显示。该研究对商用车ECAS人机交互系统的故障诊断系统设计开发具有一定的参考价值。

乘用车电控空气悬架高度控制策略

为了提高乘用车电控空气悬架在车身高度调节过程的控制精度,设计了基于粒子群的PID控制器。首先通过对空气悬架系统工作机理的分析,利用AMESim建立单轮空气悬架数学模型,针对车高调节过程中出现的“过充过放”问题,设计了基于粒子群的PID控制器,然后在AMESim-Simulink-Carsim联合仿真平台中建立了整车空气悬架模型对其控制效果进行验证。最后进行了实车测试。结果表明,所设计的基于粒子群的PID控制器在不同工况下的车身高度稳态误差均小于2 mm,且没有出现明显的高度反复调节或者控制超调现象。

ECAS客车车身高度的实时跟踪

为实现客车车身高度的精确跟踪,满足空气悬架控制要求,设计出一种基于电感式传感器的车身高度跟踪电路,传感器中的电感与跟踪电路由单片机共同控制,实现对传感器电感的充放电,单片机计算不同电感系数下的时间常数,间接获得实时的客车车身高度。并采用温度补偿电路和低温漂特性元件,适应客车工作环境温度的变化。设计出专用的滤波处理软件,既保证了车身动态高度的准确跟踪,又满足车身高度跟踪实时性的要求。试验表明,设计的车身高度跟踪系统启动后很快达到稳定且跟踪变化值在1 mm左右;当环境温度从30℃上升到80℃的过程中,跟踪高度的相对误差在1.9%左右,跟踪最大误差为5 mm,能够保证车身高度控制的准确性。

基于STF的车辆ECAS传感器故障诊断研究

电控空气悬架(electronically controlled air suspension,ECAS)系统的有效控制依赖于传感器实时采集的正确车身状态信号。针对电控空气悬架传感器卡死、恒偏差、恒增益3种故障,建立1种ECAS故障检测与隔离方法(fault detection and isolation,FDI)。建立电控空气悬架三自由度1/4车模型以及传感器故障时空气悬架模型,设计故障检测滤波器组,结合传感器实时测量值获得空气悬架输出残差,在此基础上确定故障检测指标,计算指标数值并选取适当阈值进行比较。诊断滤波器采用强跟踪滤波器方法进行设计,选取两级决策变量构造隔离决策函数,实现对故障传感器的检测与隔离。仿真分析表明,所提出的基于STF的方法实现了ECAS传感器故障的检测与隔离,有效提高了车辆控制的可靠性与安全性。

ECAS车辆车身高度调节系统与整车性能匹配研究

为解决电控空气悬架(electric control air suspension,简称ECAS)车身高度切换过程中的振荡及"过充"、"过放"现象,以空气弹簧特性为媒介,与车辆动力学相结合,对车身高度调节系统的进行建模。通过遗传算法优化车身高度调节系统PID的控制参数,提出一种新的积分分离PID控制策略。采用Matlab/Simulink搭建模型并对控制前、后仿真结果进行了对比。结果证明,所设计的控制方法能有效解决以上问题,优化后的车身高度调节系统能显著减少汽车振荡及干扰,操纵稳定性得到改善。

基于神经网络PID控制的客车ECAS设计与实现

以飞思卡尔MC9S08GB60单片机为控制核心,以亚星YBL6891H型客车为试验对象,针对空气悬架系统本身的非线性特性,采用神经PID控制算法,设计了一种通过检测车身高度对空气弹簧进行充排气,进而改变弹簧刚度的客车电控空气悬架系统。根据悬架评价指标建立了电控悬架的2自由度1/4车辆模型,通过仿真验证了该悬架系统对悬架动行程、车轮动载荷及车身垂直加速度这3项汽车行驶平顺性评价指标的改善,最后通过试验验证了所设计控制策略的正确性。

基于扩展Kalman滤波器组的ECAS系统传感器故障诊断

针对电控空气悬架(electronically controlled air suspension,简称ECAS)系统在车高调节过程中由于传感器故障频发导致控制效果变差的问题,提出一种能够对电控空气悬架系统传感器故障进行诊断的方法。首先,采用AMESim软件搭建ECAS系统物理模型以实现空气弹簧特性的精确描述,同时在Matlab/Simulink中搭建路面激励和传感器故障的数学模型;其次,针对车辆ECAS系统的非线性特性,采用扩展卡尔曼滤波器组设计故障诊断方案,并进行不同传感器不同故障类型的联合仿真;最后,搭建了1/4ECAS系统台架,进行车高调节过程中传感器故障诊断试验。试验结果表明,所提出的方法能够准确地辨识ECAS系统传感器的典型故障,较好地隔离不同的故障传感器,为ECAS系统的准确可靠运行提供了保证。

一种电控空气悬架ECU下线检测系统设计

针对传统电控空气悬架电子控制单元(Electronic Control Unit,ECU)下线检测过程中存在的人工检测精准度差、效率低等问题,开发了一款自动电控空气悬架ECU下线检测系统。分析了电控空气悬架ECU下线检测系统各项技术需求,设计了上位机+系统检测平台的系统架构;选择数据采集卡、CAN卡等部件搭建了下线检测系统检测平台;采用C#编程语言开发了上位机软件,软件采用UI界面层、业务逻辑层和数据层的三层架构,通过CAN总线通讯方式实现上位机、检测平台及待测ECU的双向通讯。测试结果表明,该下线检测系统可实现电控空气悬架ECU自动下线质量检测,并完成了测试数据的智能管理,满足电控空气悬架ECU的检测功能需求。

客车电控空气悬架系统侧跪控制策略研究

为实现两桥客车电控空气悬架系统侧跪控制,采用汽车动力学仿真软件TruckSim和逻辑控制软件Simulink&Stateflow开发客车侧跪控制策略。通过TruckSim搭建客车整车车体模型,Simulink构建的电控空气悬架模型,包括空气弹簧模型、储气罐模型、管路模型、电磁阀模型等,借助Simulink&Stateflow建立侧跪控制策略仿真模型,仿真实验结果表明,侧跪前后客车车身高度和气囊压力发生明显变化,车身侧倾角从0°增加至2°,乘客上下车更便利。

商用车电控空气悬架提升桥牵引辅助策略研究

为验证商用车的牵引辅助功能通过比例控制策略的原理及实现方式,本文以三桥商用车电控空气悬架系统为主要研究对象,利用拉格朗日方程建立整车行驶动力学的理论模型,此基础上搭建Simulink仿真模型,提出面向基于比例控制的提升桥控制策略。为分析实车应用可行性,分别在坡道工况和水平冰雪路面工况下,验证了该控制策略的牵引辅助效果,通过控制提升桥举升,有效转移驱动轴和提升桥载荷比,使车辆在符合承载要求前提下提高车辆驱动力,通过实验仿真验证该控制策略的有效性。

基于ECAS控制的模块式车辆空气悬架高度控制系统的设计与仿真

以ECAS为基础,以WABCO4728800010两位三通电磁阀和Freescale的MC9S12D64微处理器为核心元器件,开发了一种模块式的空气悬架高度控制系统,并在matlab/simulink环境下进行了仿真验证。该系统的高度控制策略分为启动控制模块、动态调节模块、手动调节模块以及误差调节模块,由模式选择开关来决定不同模块的工作状态,逻辑控制准确、调试方便。模块式的设计大幅降低了系统的复杂程度,同时也将降低软件的开发周期和成本。

基于AMESim的ECAS车高调节模糊自适应控制研究

针对电控空气悬架在车身高度调节过程中存在的过充、过放以及目标值附近的震荡等不良现象,基于AMESim建模与仿真平台建立了单轮ECAS车高调节系统物理模型,准确获取了ECAS在车高调节过程中存在的复杂动态特征,利用Matlab设计了ECAS车高调节模糊自适应控制器,对车高调节过程中进入或流出空气弹簧内的气体质量流量进行准确控制,并进一步采用PWM技术将连续的气体质量流量控制信号转化为离散的高速开关电磁阀直接控制信号,从而实现对ECAS车高调节系统的实时控制。基于AMESim和Matlab进行ECAS车高调节模糊自适应控制器实际控制性能的联合仿真研究,仿真结果表明,所设计的控制器能够实现车身高度的有效调节。

轿车ECAS充放气时平顺性的控制研究

为了研究电子控制空气悬架(ECAS)充放气时汽车的平顺性,针对丰田某一款车的电子控制主动式空气悬架,在空气悬架模拟试验台上,根据位移传感器测得在不同时间下空气悬架充放气时的高度以及实验过程中空气悬架结构变化的特点,建立悬架刚度的数学模型;同时,结合减震器阻尼系数与悬架刚度之间的理论关系,建立1/4的主动式空气悬架数学模型。在Matlab/Simulink中,设计一个模糊PID控制器,在D级高斯白噪声路面上对汽车进行ECAS充放气时平顺性的仿真。结果表明:通过对Fuzzy-PID控制前后的数据结果对比可知,采用模糊PID控制策略后,大大改善了空气悬架充放气时汽车的舒适性,为空气悬架进行充放气时的控制策略提供了一种可行的方法。

Stiffness-damping matching method of an ECAS system based on LQG control

A novel method of matching stiffness and continuous variable damping of an ECAS(electronically controlled air suspension) based on LQG(linear quadratic Gaussian) control was proposed to simultaneously improve the road-friendliness and ride comfort of a two-axle school bus.Taking account of the suspension nonlinearities and target-height-dependent variation in suspension characteristics,a stiffness model of the ECAS mounted on the drive axle of the bus was developed based on thermodynamics and the key parameters were obtained through field tests.By determining the proper range of the target height for the ECAS of the fully-loaded bus based on the design requirements of vehicle body bounce frequency,the control algorithm of the target suspension height(i.e.,stiffness) was derived according to driving speed and road roughness.Taking account of the nonlinearities of a continuous variable semi-active damper,the damping force was obtained through the subtraction of the air spring force from the optimum integrated suspension force,which was calculated based on LQG control.Finally,a GA(genetic algorithm)-based matching method between stepped variable damping and stiffness was employed as a benchmark to evaluate the effectiveness of the LQG-based matching method.Simulation results indicate that compared with the GA-based matching method,both dynamic tire force and vehicle body vertical acceleration responses are markedly reduced around the vehicle body bounce frequency employing the LQG-based matching method,with peak values of the dynamic tire force PSD(power spectral density) decreased by 73.6%,60.8% and 71.9% in the three cases,and corresponding reduction are 71.3%,59.4% and 68.2% for the vehicle body vertical acceleration.A strong robustness to variation of driving speed and road roughness is also observed for the LQG-based matching method.

Vehicle height and leveling control of electronically controlled air suspension using mixed logical dynamical approach

Vehicle height and leveling control of electronically controlled air suspension(ECAS) still poses theoretical challenges for researchers that have not been adequately addressed in prior research. This paper investigates the design and verification of a new controller to adjust the vehicle height and to regulate the roll and pitch angles of the vehicle body(leveling control) during the height adjustment procedures. A nonlinear mechanism model of the vehicle height adjustment system is formulated to describe the dynamic behaviors of the system. By using mixed logical dynamical(MLD) approach, a novel control strategy is proposed to adjust the vehicle height by controlling the on-off statuses of the solenoid valves directly. On this basis, a correction algorithm is also designed to regulate the durations of the on-off statuses of the solenoid valves based on pulse width modulated(PWM) technology, thus the effective leveling control of the vehicle body can be guaranteed. Finally, simulations and vehicle tests results are presented to demonstrate the effectiveness and applicability of the proposed control methodology.

客车空气悬架电子控制系统(ECAS)

介绍客车空气悬架电子控制系统(ECAS)的特点、组成、工作原理、功能和应用方法等。

ECAS系统在重型车辆上的应用

阐述ECAS电控系统在空气悬架中的结构组成及工作原理,介绍ECAS系统在实际使用过程中的注意事项。