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.

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.

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.

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.

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。

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。

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.

基于系统实时状态观测的车身高度动态调节控制研究

本文提出了一种基于实时状态观测的车辆车身高度动态调节控制策略,以实现多种路况条件下的车辆高度动态精确控制.不同的道路条件下驾驶员对车辆高度以及姿态稳定性存在不同程度的性能需求,这就需要考虑通过系统外部随机激励来实现车辆高度的动态精确调节与控制.电控空气悬架系统具有非线性特性,仅以悬架动挠度作为参考的车辆高度调节会在随机扰动作用过程中产生极大偏差.因此,本文基于空气弹簧结构与气体流体特性,使用无迹卡尔曼滤波状态观测算法提出了一种悬架静平衡位置观测方法;根据所获知的静平衡位置信息,进一步使用滑模控制算法进行随机激励作用下的悬架高度与车身姿态动态调节.经过模型数值仿真和实车试验验证的结果可知,提出的动态调节控制策略可以实现随机扰动与激励作用下的车辆高度精确控制与车身姿态稳定性保持,从而实现不同道路条件与工况下的车辆综合性能.

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。

基于TC275的电控空气悬架控制单元标定系统设计

为实现电控空气悬架系统电子控制单元中关键参数的测量及标定,使开发的控制策略在不同类型车辆中具有较好的移植性,本文基于控制器局域网标定协议(controller area network calibration protocol,CCP),对电控空气悬架标定系统进行分析,并开发了基于英飞凌TC275单片机的电控空气悬架标定驱动程序,同时采用上位机标定软件CANape,对电控空气悬架的标定参数进行测量和标定。研究结果表明,本文设计的标定系统,可以实现对电子控制单元的在线标定,完成测量标定任务,可以使开发的控制策略根据不同车型、不同驾驶人群进行调整,有效提高了开发效率。该研究提高了车辆的平顺性及燃油经济性。

基于SOA-LQR控制的电控空气悬架系统

为研究电控空气悬架系统(ECAS)的控制策略,基于MATLAB/Simulink平台搭建了空气悬架模型,以白噪声路面作为系统输入,采用LQR最优控制器实现悬架力的输出,并以人群搜索算法作为控制器优化方式,完成对空气悬架LQR控制器中所包含的主要指标权重数据优化,仿真结果表明,优化后的LQR控制系统对于ECAS的性能提升具有较好效果,其中簧上质量垂直加速度、动挠度瞬态响应峰值相较无控制状态分别减小了45.84%和39.07%,均方根值则分别减小了54.98%和35.4%,整车平顺性得到较大改善。

电控空气半主动悬架控制策略分析

为了提高商用车行驶稳定性和运载货物完整度,应用流体力学和牛顿力学建立MATLAB/Simulink空气弹簧可变刚度悬架模型。根据汽车实际工况需求,设计一种具有车身高度调节死区的分层架构控制策略,并采用比例-积分-微分(PID)算法控制脉冲宽度调制(PWM)信号占空比,进而改变电磁阀开闭状态,最后对比分析控制前后悬架动态特性。仿真结果表明,在车速分别为50 km/h和90km/h的B级随机路面条件下,PID控制策略悬架动挠度和簧载质量加速度均方根值有不同程度改进,有效提高了电控空气悬架动态性能。

智轨电车轴重分配与调节方法的研究与应用

以三编组智轨电车为计算模型,详细阐述了智轨电车轴重、轮重的计算方法和过程。设计前先根据计算模型优化车辆设备布局,计算出理论轴重、轮重值,再对实际车辆过检测线称重数据进行分析计算来验证理论模型,结果非常接近我国对城市轨道车辆轮重偏差的规定。最后通过增加电子控制空气悬架系统来调节轮重和轴重偏差,很好地优化了智轨电车轮重和轴重偏差问题,使其结果明显优于国家标准要求。

电子控制空气悬架高度调节过程非线性模型

电子控制空气悬架的高度调节过程是一个复杂的非线性过程,为研究高度调节过程中对空气弹簧充气或者排气时悬架的动力学特性以及作为后续悬架高度控制策略的研究基础,对电子控制空气悬架高度调节中的弹簧内气体热力学过程、簧载质量动力学过程进行分析,推导出高度调节过程中电磁阀开启期间和关闭后的空气弹簧内压力梯度方程、气体回路的流量方程、以及簧载质量动力学方程,建立带电磁阀功能的高度调节过程非线性模型,并通过电磁阀在不同脉冲时间下空气弹簧充气和排气的整车试验对所建立的高度调节过程模型进行验证,试验结果与仿真结果吻合较好。研究结果表明所建立的模型能正确描述电磁阀关闭前后空气弹簧内的气体状态以及电磁阀关闭以后的悬架在阻尼力作用下运动的迟滞特性。

基于模型的电控空气悬架系统控制策略与实车试验

设计了以Freescale XDT512为核心芯片,且由最小系统、电源模块、驱动电路、速度处理模块、两向加速度模块、模拟量输入模块和通信模块等组成的电控空气悬架系统(ECAS)电子控制单元;利用基于模型的设计方法开发了电控空气悬架系统的控制策略模型,其主要由自动模式子模块、手动模式子模型和维修模式子模型等组成;在自动模式下,根据车速自动调整车身高度;在手动模式下,驾驶员可通过人机操控界面,自主地设定车身高度;通过维修模式,可禁止电控空气悬架工作,防止出现误动作。通过合理设计测试用例对所设计的控制模型实施结构性、功能性测试;经控制模型的定点化处理,并利用RTW代码生成技术将所设计的控制模型转换为应用层程序,并与底层驱动相互集成后,编译下载至所开发的ECAS电子控制单元;开展实车验证试验,试验结果表明所设计的控制策略能较好地满足设计要求。

电控空气悬架车高调节与整车姿态控制研究

针对电控空气悬架在车高调节过程中存在的过充、过放以及振荡等不良现象,提出一种能够对气体质量流量进行自适应调节的神经网络PID控制方法。根据车辆系统动力学和变质量充放气系统热力学理论,建立了电控空气悬架车高调节数学模型,设计了车高调节BP神经网络PID控制器,并对控制器的实际性能进行了仿真验证。在此基础上,为了进一步防止车高调节过程中因四角高度调节不同步而引起的整车姿态失稳现象,基于模糊控制算法对系统局部控制量进行了修正,从而形成整车姿态模糊控制器。最后,基于D2P快速开发平台搭建了电控空气悬架车高调节控制系统,进行了整车台架试验。试验结果表明,所设计的控制系统不仅能够实现车身高度的有效调节,同时还能抑制车高调节过程中的整车姿态变化。

电控空气悬架系统阻尼多模式自适应切换控制研究

提出了一种阻尼多模式自适应切换控制思想,根据车辆实际行驶工况和电控空气悬架性能特点,分别设计了车身高位、车身中位、车身低位以及转向工况4种阻尼控制模式,并采用逻辑判断方法制定了各模式间的切换策略,通过Simulink/Stateflow建立了多模式自适应切换控制系统,使得系统能够根据实际工况选择最佳的阻尼控制模式。在此基础上,基于不同模式所侧重的控制目标,分别设计了相应的阻尼力局部控制器,从而保证了系统的局部控制性能。最后进行了控制系统的实车道路试验,验证所提出的电控空气悬架系统阻尼多模式自适应切换控制方法的有效性和实用性。

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。