Active Roll Control for Passenger Cars

The development of a mathematical model of a limited bandwidth hydro-pneumatic suspension that is incorporated into a vehicle handling model is described. The combined model is used to evaluate a suitable control strategy for eliminating body roll during a cornering manoeuvre. The philosophy behind the roll control strategy has been to use feedback measurements of the body motions which do not compromise the ride control. A study of the influence of the position of the body motion feedback transducer on the effectiveness of the system to reduce the body roll is presented. Non-linear modelling of the suspension components for a 0.8g cornering manoeuvre has revealed performance limitations. Conclusions are drawn as to the effectiveness of the control scheme.     

JYXR系列舰用挠性接管研究

  目的  为了研究凯夫拉纤维增强型挠性接管（FW-FP）管体发生局部异常变形而引发管体破裂失效的问题,  方法  提出一种基于电阻检测原理的管体变形检测方法,通过传感器缠绕模型的设计,分析管体3种变形状态。运用建立的基准阈值模型,对典型的DN100挠性管体进行数值计算分析。  结果  结果表明,管体局部异常变形引起电路电流的变化量可达0.25 A,而管体正常变形引起电路电流的变化量可忽略不计。  结论  所提方法可有效识别管体上的局部异常变形,并可排除正常变形带来的信号干扰。该检测方法得到的结果可为后续评估此类挠性接管管体使用寿命提供依据。     

桥墩防落石碰撞柔性设计方法及分析

基于动力学基本原理,从非线性、接触以及本构关系计算理论建立落石-桥墩防撞物柔性碰撞精细化计算模型,并对关键计算参数给出建议取值.利用钢结构柔性变形吸收落石碰撞能量,提出一种桥墩防落石碰撞柔性设计方法,并详细给出该防落石碰撞构造措施的结构组成形式.利用ANSYS/LS-DYNA动力分析计算程序,考虑几何、材料双重非线性,精细化数值仿真计算落石撞击防撞物的动态全过程,以一个偏安全的极限碰撞状态,分别从运动行为(撞击力、位移、速度、加速度)以及能量转换(系统动能、系统变形能)角度进行计算结果与数据分析,证明所提出的柔性防撞设计思路以及防撞措施的合理性与优越性.     

Transient characteristics of emissions during engine start/stop operation employing a conventional gasoline engine for HEV application

In this paper, we investigate the transient characteristics of combustion and emissions during engine start/stop operations in hybrid electric vehicle (HEV) applications. Hydrocarbon (HC) emissions during the initial 2^nd∼9^th cycles are found to be significantly greater when the engine is quickly started under the original engine calibration mode. Lower intake manifold absolute pressure (MAP) was also found to cause larger residual gas dilution and poor combustion, resulting in a higher HC concentration when the cranking speed was increased. The post-catalyst HC concentration was found in the way of initially decrease and then to increase again as the cranking speed was increased. A lowest concentration value was achieved at a cranking speed of 1000 r/min. Engine shut-down by fuel cut-off was shown to produce lower emissions than shut-down by ignition cut-off as one can avoid misfire of the last fuel injection cycle. The fuel deposited during the stop process seems to impact engine restart enrichment mostly during the initial 0.7 s for this engine, whose performance is dominated by the MAP transition characteristic and the time coefficient for fuel vaporization in this time period     

A fundamental investigation of tilt control systems for narrow commuter vehicles

One way of addressing traffic congestion is by efficiently utilizing the existing highway infrastructure. Narrow tilting vehicles that need a reduced width lane can be part of the solution if they can be designed to be safe, stable, and easy to operate. In this paper, a control system that stabilizes the tilt mode of such a vehicle without affecting the handling of the vehicle is proposed. This control system is a combination of two different types of control schemes known as steering tilt control (STC) and direct tilt control (DTC) systems. First, different existing variations of both STC and DTC systems are considered and their shortcomings analysed. Modified control schemes are then suggested to overcome the deficiencies. Then a new method of integrating these two control schemes that guarantees smooth switchover between the controllers as a function of vehicle velocity is proposed. The performance of the proposed STC, DTC, and integrated systems is evaluated by carrying out simulations for different operating conditions and some experimental work. The design of a second-generation narrow tilting vehicle on which the developed control system has been implemented is presented.     

Robust lane markings detection and road geometry computation

Detection of lane markings based on a camera sensor can be a low-cost solution to lane departure and curve-over-speed warnings. A number of methods and implementations have been reported in the literature. However, reliable detection is still an issue because of cast shadows, worn and occluded markings, variable ambient lighting conditions, for example. We focus on increasing detection reliability in two ways. First, we employed an image feature other than the commonly used edges: ridges, which we claim addresses this problem better. Second, we adapted RANSAC, a generic robust estimation method, to fit a parametric model of a pair of lane lines to the image features, based on both ridgeness and ridge orientation. In addition, the model was fitted for the left and right lane lines simultaneously to enforce a consistent result. Four measures of interest for driver assistance applications were directly computed from the fitted parametric model at each frame: lane width, lane curvature, and vehicle yaw angle and lateral offset with regard the lane medial axis. We qualitatively assessed our method in video sequences captured on several road types and under very different lighting conditions. We also quantitatively assessed it on synthetic but realistic video sequences for which road geometry and vehicle trajectory ground truth are known.     

偏压隧道处治措施及稳定性分析

以上瑞高速公路怀新段第8合同段青山冲隧道为工程实例,针对左线出口端洞口浅埋偏压情况,为了节约工程投资,实施了反压回填的处治方案,采用数值模拟分析及现场监控量测数据分析了偏压隧道支护结构的受力状态和稳定性,可供类似工程参考.     

Estimation of maximum road friction coefficient based on Lyapunov method

With the real time and accurate information of motor torque and rotation speed of the four-in-wheel-motordrive electric vehicles, a slip based algorithm for estimating maximum road friction coefficient is designed using Lyapunov stability theory. Modified Burckhardt tire model is used to describe longitudinal slip property of the tire. By introducing a new state variable, a nonlinear estimator is proposed to estimate the longitudinal tire force and the maximum road friction coefficient simultaneously. With the appropriate selection of estimation gain, the convergence of the estimation error of the tire longitudinal force and maximum road friction coefficient is proved through Lyapunov stability analysis. In addition, the error is exponentially stable near the origin. Finally the method is validated with Carsim-Simulink co-simulation and real vehicle tests under multi working conditions in acceleration situation which demonstrate high computational efficiency and accuracy of this method.     

Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 1

This paper is review of the characterization of exhaust particles from state-of-the-art internal combustion engines. We primarily focus on identifying the physical and chemical properties of nano-particles, i.e., the concentration, size distribution, and particulate matter (PM) morphology. Stringent emissions regulations of the Euro 6 and the LEV III require a substantial reduction in the PM emissions from vehicles, and improvements in human health effects. Advances in powertrains with sophisticated engine control strategies and engine after-treatment technologies have significantly improved PM emission levels, motivating the development of new particle measurement instruments and chemical analysis procedures. In this paper, recent research trends are reviewed for physical and chemical PM characterization methods for gasoline and diesel fueled engines under various vehicle certification cycles and real-world driving conditions. The effects of engine technologies, fuels, and engine lubricant oils on exhaust PM morphology and compositions are also discussed.     

Methodology for bus structure torsion stiffness and natural vibration frequency prediction based on a dimensional analysis approach

Engineering bus design requires testing of bus structures prototypes in order to guarantee a certain level of strength and an appropriate static and dynamic behavior of the bus superstructure when exposed to road loads. However, experimental testing of real bus structures is very expensive as it requires expensive resources and space. If testing is done on a scale bus model the previous required expenses are considerably reduced. Therefore, a novel methodology based on dimensional analysis applied to bus structure prediction to evaluate the bus structure static and dynamic performance is proposed. The static performance is evaluated attending to torsion stiffness and the dynamic in terms of the natural vibration frequencies and rollover threshold. A scale bus has been manufactured and dimensionless parameters have been defined in order to project the results obtained in the scale bus model to a larger model. Validation of the proposed methodology has been carried out under experimental and finite element analysis.