Vehicle tests of a longitudinal control law for application to stop-and-go cruise control

This paper presents the implementation and vehicle tests of a vehicle longitudinal control scheme for Stop and Go cruise control. The control scheme consists of a vehicle-to-vehicle distance control algorithm and throttle/brake control algorithm for acceleration tracking. The desired acceleration of a vehicle for vehicle-to-vehicle distance control has been designed using Linear Quadratic optimal control theory. Performance of the control algorithm has been investigated via vehicle tests. A millimeter wave radar sensor has been used for distance measurement. A stepper motor and an electronic vacuum booster have been used for throttle/ brake actuators, respectively. It has been shown that the proposed control algorithm can provide satisfactory performance.     

Development of TCS slip control logic based on engine throttle control

Slip control systems are used to prevent wheel slipping and to improve acceleration performance, stability and steerability on slippery roads through the engine torque and/or brake torque control. This paper mainly deals with the engine control algorithm via adjustment of the engine throttle angle. The slip control algorithm developed in this research includes a control gain scheduling part and a road estimating part to enhance control performance. Various actual vehicle tests have been carried out on low friction roads in order to verify the developed slip control algorithm. The test results show that the controlled vehicle is superior to the non-controlled vehicle in acceleration performance and stability.     

电机驱动式汽车辅助制动装置的研究

针对液（气）压辅助制动系统成本较高以及电子真空助力器（EVB）响应速度慢等问题,开发了一套电机驱动式汽车辅助制动装备,该装置的主要功能是在出现追尾危险时通过驱动模块驱动电机工作,拉动制动踏板,从而代替驾驶员动作,完成期望的制动过程,以减少交通事故的发生。     

轿车整车动态真空度试验与分析

不同车辆制动踏板的软硬程度是不同的,造成差异的主要原因在于踏板是否具备助力机构.一般情况下,轿车采用的是真空助力器的结构.在不同大气压力下,车辆真空助力器内的真空度水平会有所变化,直接导致在高海拔地区整车制动系统的表现相比低海拔地区存在一定差异,甚至存在安全隐患.提出了轿车整车动态真空度的实验方法,对不同工况下的整车动态真空度进行试验,并对结果进行分析,为车辆制动系统的改进提供依据,同时避免了车辆上市后的潜在风险.     

一种基于EMS标定的车辆真空度不足的解决方案

传统内燃机汽车,多采用真空助力伺服制动系统来实现助力。其真空源来自于发动机进气歧管。现在汽车随着发动机排量的减小和负载的增加,真空度在某些工况下将出现严重不足的问题,尤其是高海拔地区。通过对发动机EMS的标定,实现了对整车真空助力系统的适应性优化。整车道路性试验表明,优化后的真空助力系统满足整车使用要求。     

A Vehicle stop-and-go control strategy based on human drivers driving characteristics

A vehicle cruise control strategy designed based on human drivers driving characteristics has been investigated. Human drivers driving patterns have been investigated using vehicle driving test data obtained from 125 participants. The control algorithm has been designed to incorporate the driving characteristics of the human drivers and to achieve natural vehicle behavior of the controlled vehicle that would feel comfortable to the human driver. Vehicle following characteristics of the cruise controlled vehicle have been investigated using real-world vehicle driving test data and a validated simulation package.     

发动机辅助制动性能仿真研究

通过对发动机辅助制动工作过程进行理论分析,建立了发动机辅助制动计算模型,根据辅助制动相关参数（包括排气门开度、发动机转速和排气背压等）,对发动机辅助制动进行了单因素和多因素条件下的仿真研究及试验验证。结果表明：随着发动机转速的升高,缸内压力增大,且压力峰值更靠近上止点;制动扭矩随转速的升高而增大,减压制动时制动扭矩最大,发动机制动时制动扭矩最小;发动机转速一定时,泄漏制动和减压制动分别有一对应的最佳排气门开度值,并且转速越高,排气门开度最佳值越大,排气背压越高,制动扭矩越大。     

CVT ratio control for improvement of fuel economy by considering powertrain response lag

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.     

Constant speed control for complex cross-section welding using robot based on angle self-test

Expandable profile liner（EPL） is a promising new oil well casing cementing technique, and welding is a major EPLs connection technology. Connection of EPL is still in the stage of manual welding so far, automatic welding technology is a hotspot of EPL which is one of the key technologies to be solved. A robot for automatic welding of＂8＂ type EPL is studied. Four quadrants of mathematical equations of the 8-shaped cross-section track of EPL, consisting of multiple arcs, are established. Mechanism program for complex cross-section welding of EPL based on angle detection is proposed according to characteristics of small size, small valleys, and large forming errors, etc. A welding velocity vector control model is established by linkage control of a welding vehicle, a small driven actuator, and a height tracking mechanism. A constant speed control model based on an angle and symmetrical analysis model of rectangular coordinate system for EPL is built. Constraint conditions of constant speed control between each section are analyzed with 4 sections in first quadrant as an example, and cooperation work mechanism of the welding vehicle and the small tracking actuator is established based on pressure detection. The constant speed control model using angle self-test can be used to avoid the need for a precise mathematical model for tracking control and to adapt manufacture and installation deviation of EPL workpiece. The model is able to solve constant speed and trajectory tracking problems of EPL cross-section welding. EPL seams welded by the studied robot are good in appearance, and non-destructive testing（NDT） shows the seams are good in quality with no welding defects. Bulge tests show that the maximum pressure of welded EPL is 35 MPa, which can fulfill expansion performance requirements.     

Design of a field programmable gate array based test launch and control system for hybrid vehicle

In order to satisfy the throttling and multiple restart characteristics of the hybrid rocket engine and guarantee the controllability and security of hybrid rocket, the test launch and control system for hybrid vehicle needs to achieve ground power control, serial communication with the flight control computer and the telemetry system, onboard thermal battery activation, battery voltage acquisition, power conversion, pressure monitoring, valve control, booster ignition, power-off and remote pressure relief in emergency. Considering the complexity of the test launch and control system for hybrid system and the advantages of Field Programmable Gate Array (FPGA), such as, a large number of I/O ports, ability to efficiently implement large-scale systems and programmability, a FPGA based test launch and control system for a type of hybrid vehicle was designed. Many conducted ground and flight experiments have proved that the system has superior performance in integration, universalization, miniaturization, automation and can perfectly meet the needs of the hybrid vehicle.     

基于改进PID算法的EM-CVT速比控制研究

机电控制CVT(EM-CVT)是一种新型无级变速传动装置,其速比跟随误差是作为评价车辆操纵性能的重要指标之一。为了对车辆行驶过程中EM-CVT与发动机动态匹配技术进行研究,通过实验获取了发动机的两种工作模式的外特性;并根据EM-CVT传动机理,理论分析车速与速比间的关系。以PID为基础,提出一种改进PID控制算法实现速比控制,并进行实验验证。实验结果表明,采用改进PID控制算法能获得较好的速比控制,具有实际应用价值。     

考虑车间反应时距的汽车自适应巡航控制策略

通过引入车间反应时距的概念,使用单一控制算法实现汽车自适应巡航控制（Adaptive cruise control,ACC）。结合熟练驾驶员经验,使用车间反应时距定量描述自车何时对目标车辆做出反应,将ACC系统分为上位控制器和下位控制器,给出考虑车间反应时距的上位控制器架构,分别设计线性二次型调节器（Linear quadratic regulator,LQR）和模型预测控制器（Model predictive control,MPC）,通过MATLAB/Simulink与CarSim联合仿真初步验证系统可行性,并以乘用车辆为试验平台在平直铺装路进行实车试验。仿真及实车试验结果表明：目标车辆信息跳变、目标车辆行驶速度超过自车驾驶员设定限速时,考虑车间反应时距的LQR或MPC控制器均能有效处理复杂交通环境信息,实现自车安全、舒适行驶,有效避免模式切换过程中车辆加速度突变,提升车内乘员乘车体验。     

插电式混合动力汽车预测控制策略的研究

针对插电式混合动力汽车(PHEV)传统控制策略没有考虑未来车速的问题,通过对汽车未来行驶车速进行预测,在整车行驶模式下提出了一种把汽车未来车速信息考虑进当前的控制策略,从而实现了对发动机和电机转矩的合理分配。通过把新开发的基于车速信息的预测控制策略嵌入到ADVISOR中,在欧洲城市循环工况(NEDC)下进行了仿真分析。仿真结果表明:对汽车未来行驶车速进行预测的控制策略能够实现对发动机和电机转矩的进行合理分配,百公里油耗约为6.5L,相比基于规则控制策略燃油经济性提高了约7.14%,而且排放也有所降低,从而验证了基于预测信息的控制策略的有效性。     

MB-CVT电液控制系统智能优化设计

为了提高配有金属带式无级变速器车型燃油经济性,提出基于滑模极值搜索理论的控制算法和基于滑模极值搜索控制与传统夹紧力控制相结合的一体化式联合控制方法;设计了滑模极值搜索控制和传统液压控制合为一体化的联合控制系统。建立具有非线性、离散性的数学模型;分析无级变速器传动效率和金属带滑差率在一定速比下存在特殊曲线关系;测试主/从动轮夹紧力比值系数,完成了速比跟踪控制器及变化率控制流程设计。依据滑模极值搜索算法原理,完成了滑模极值搜索控制器设计。在具有环境仓的转鼓试验台上进行整车试验,试验结果表明:采用一体化式控制的金属带式无级变速器车型油耗为7.18L/100km,比传统控制系统的油耗降低约5.64%;主、从动压力安全系数倒数指标均小于1。满足整车提高燃油经济需求的可靠性、稳定性及优化性能。     

Optimal engine operation by shift speed control of a CVT

In this paper, an algorithm to increase the shift speed is suggested by increasing the line pressure for a metal belt CVT. In order to control the shift speed, an algorithm to calculate the target shift speed is presented from the modified CVT shift dynamics. In applying the shift speed control algorithm, a criterion is proposed to prevent the excessive hydraulic loss due to the increased line pressure. Simulations are performed based on the dynamic models of the hydraulic control valves, powertrain and the vehicle. It is found from the simulation results that performance of the engine operation can be improved by the faster shift speed, which results in the improved fuel economy by 2% compared with that of the conventional electronic control CVT in spite of the increased hydraulic loss due to the increased line pressure.     

智能车辆的纵向运动控制

建立使用发动机中等复杂模型和非线性刹车模型的车辆纵向运动数学模型。使用基于模糊逻辑和遗传算法的复杂对象控制器自动设计方法设计刹车控制器,构造一种油门和刹车切换逻辑,再基于刹车控制器和切换逻辑使用自动设计方法设计油门控制器,共同构成纵向运动控制器(LMC)。仿真检验LMC在IV巡航控制和自适应巡航控制中的有效性,结果表明所设计的LMC完全可以满足IV纵向运动高精度、强鲁棒性和平顺性的要求     

高速伸缩臂叉车行走电控系统的设计

设计了高速伸缩臂叉车静液压传动行走电控系统。采用PID控制器控制车辆行走速度,利用自适应滤波原理,设计了自适应预测滤波器,预测车辆目标工作状态下的系统压力差。实现了发动机与变量泵的复合控制,提高了车辆的控制特性,优化了发动机的工况。     

Idle speed modeling and optimal control of a spark-ignition engine

A model of engine dynamics is developed. The model is a MISO (Multi Input Single Output) linear model which has two inputs and one output. One input is the spark timing, and the other is the ISCV (Idle Speed Control Valve) position. The output is the angular speed of an engine. The reliability of the developed model is confirmed by comparing the measured response of the engine to step inputs and external disturbance with the simulation results. In order to reduce the steady state error, an integrator state is inserted to the state equation. An engine idle speed controller is designed using optimal control theory based on the model. The performance variation of the controller to the various design parameters is simulated. On the basis of the simulation and the experimental data, the design parameters are determined. The developed controller reduced the idle speed drop caused by an external load change and recovered the desired idle speed in one second.     

Control of gear shifts in dual clutch transmission powertrains

To achieve the best possible responses during shifting in dual clutch transmissions it is commonplace to integrate clutch and engine control, while the clutch is used to match speeds between the engine and wheels via reduction gears, poor engine control can lead to extended engagement times and rough/harsh shift transients. This paper proposes a method for combined speed and torque control of vehicle powertrains with dual clutch transmissions for both the engine and clutches. The vehicle powertrain is modelled as a simple four degree of freedom system with reduction gears and two clutches. Including a detailed clutch hydraulic model, comprising of the direct acting solenoids and clutch piston with the hydraulic fluid modelled as a compressible fluid. Powertrain control is realised through control of clutch solenoids and manipulation of the engine throttle input. Sensitivity study of clutch performance evaluating inaccurate torque estimation demonstrated variance in the response of the hydraulic system, with an indicative simulation of poor estimation resulting in increased powertrain vibration during and after shifting. Simulations are conducted to demonstrate the capacity for this method of engine and clutch control to further reduce shift transients developed in dual clutch transmission powertrains. The obtained results also show that the adoption of torque based control techniques for both the clutch and engine, which makes use of the estimated target clutch torque, significantly improves the powertrain response as a result of reduction in the lockup discontinuities.     

基于转矩的低附路面机械式自动变速器控制策略

从机械式自动变速器控制系统所能获取的有限数据,判断行驶路面的附着系数以及车辆轮胎打滑情况,并进行驱动防滑控制;通过发动机转矩、变速器数据、整车状态等对车辆正常的加速度范围进行计算,并和轮速加速度进行比较,以确定车轮打滑情况。根据轮加速度的大小进一步判断路面附着系数。轮胎打滑时,通过对发动机的降扭和离合器的控制,实现驱动防滑的控制;在试验车辆上进行低附路面识别和控制的试验,能够正确识别出路面附着系数。在低附路面起步时,通过打滑时发动机转矩和离合器的控制,避免了车轮连续的滑转,大大提高了车辆的稳定性。这说明该低附路面识别和控制方法是可行的,能够在车上使用。