Hierarchical modeling of semi-active control of a full motorcycle suspension with six degrees of freedoms

Hierarchical control is a new control framework in the vehicle vibration control field. In this paper, a hierarchical modeling method is presented to form a different motorcycle model, compared to the traditional model with six degrees of freedoms (DOF), so as to construct hierarchical modeling control. The whole control framework is composed of a central control, two local controls and two uncontrollable parts. The front and rear wheel systems of a motorcycle are all dealt with by using two independent local 2-DOF systems. The driver and engine act as uncontrollable passive parts. The central control is composed of an algorithm made up of some dynamic equations that harmonize local relations. The vertical and pitch accelerations of the suspension center are treated as central control objects. With the help of Linear Quadratic Gaussian (LQG) algorithms adopted by two local controls, respectively, and Matlab software, some results of the simulation show that hierarchical modeling control requires less CPU time, reduces respond time and improves ride quality.     

Effect of the number of fuel injector holes on characteristics of combustion and emissions in a diesel engine

The diesel combustion process is highly dependent on fuel injection parameters, and understanding fuel spray development is essential for proper control of the process. One of the critical factors for controlling the rate of mixing of fuel and air is the number of injector holes in a diesel engine. This study was intended to explore the behavior of the formation of spray mixtures, combustion, and emissions as a function of the number of injector hole changes; from this work, we propose an optimal number of holes for superior emissions and engine performance in diesel engine applications. The results show that increasing the number of holes significantly influences evaporation, atomization, and combustion. However, when the number of holes exceeds a certain threshold, there is an adverse effect on combustion and emissions due to a lack of the air entrainment required for the achievement of a stoichiometric mixture.     

Optimum distribution of yaw moment for unified chassis control with limitations on the active front steering angle

This paper describes an optimum distribution method for yaw moment for use with unified chassis control (UCC) with limitations on the active front steering (AFS) angle. Although the UCC has been assumed to have no AFS angle limitation in the literature, a physical limitation exists in real applications. To improve upon the previous method, a new optimum distribution method for yaw moment is proposed that takes this limitation into account. This method derives an optimum longitudinal/lateral force using the Karush-Kuhn-Tucker (KKT) optimality condition, and a simulation is performed to validate the proposed method. The simulation results indicate that the limitation on the AFS angle increases longitudinal braking force and, therefore, reduces the vehicle speed and the side-slip angle.     

Active coolant control strategies in automotive engines

The coolant flow rate in conventional cooling systems in automotive engines is subject to the mechanical water pump speed, and high efficiency in terms of fuel economy and exhaust emission is not possible given this limitation. A new technology must be developed for engine cooling systems. The electronic water pump is used as a substitute for the mechanical water pump in new engine cooling systems. The new cooling system provides more flexible control of the coolant flow rate and engine temperature, which previously relied strongly on engine driving conditions such as load and speed. In this study, the feasibility of two new cooling strategies was investigated using a simulation model that was validated with temperatures measured in a diesel engine. Results revealed that active coolant control using an electronic water pump and valves substantially contributed to a reduction of coolant warm-up time during cold engine starts. Harmful emissions and fuel consumption are expected to decrease as a result of a reduction in warm-up time.     

考虑引桥工作状态下的短跨板桥的车致动力反应

通过把车辆和桥梁看作一个耦合系统来建立模型去求解桥梁的车致动力反应。文中研究了由AASHTO HS20卡车引起的不同跨径的短板桥的动力反应。利用参数分析来研究不同车速及不同路面状况所产生的效应。研究发现,引起桥梁动力反应峰值的临界车速遵循描述列车致桥梁共振的规则。分析中考虑了引桥状态的影响包括引桥桥头断层及引桥板形变。虽然引桥变形对桥梁的动力反应影响微小,但是在研究中却发现引桥桥头断层能在短跨板桥中引起显著的动力反应。该文对评价既有短跨径桥梁的动力性能有很大的意义,因此值得中国从业者借鉴。     

Traffic-balancing algorithm for can systems with dual communication channels to enhance the network capacity

The controller area network (CAN) is the dominant protocol for in-vehicle network (IVN) systems because it provides bounded transmission delay among electronic control units (ECUs) at data rates between 100 Kbps and 1 Mbps. Many automotive companies have chosen the CAN protocol for their chassis network system of intelligent vehicles. However, the increasing number of ECUs in intelligent vehicles and the need for more intelligent functions require a network system with more network capacity and real-time capability. As one approach to enhance the network capacity of a CAN system, this paper introduces a CAN system with dual communication channels. This paper also presents a traffic-balancing algorithm that predicts the traffic of each channel and allocates frames to the most appropriate channel. An experimental testbed using commercial off-the-shelf microcontrollers with two CAN controllers was used to demonstrate the feasibility of the traffic-balancing algorithm.     

Development of the Sungkyunkwan University Driving Simulator (SKUD) for Human-Machine Interface studies of Car Navigation Systems

Driving simulators are useful tools that can be used not only to test the components of future cars, but also to evaluate the telematics service and HMI (Human-Machine Interface). However, driving simulators that are currently available cannot be implemented to test and evaluate a real commercial telematics service system because the GPS (Global Positioning System), which contains basic functional support for the telematics module, does not work in the VR (virtual reality) environment. A driving simulator, together with the GPS simulator, can be used to study the HMI to evaluate commercial CNS (Car Navigation Systems). In this paper, Sungkyunkwan University Driving Simulator (SKUD) is developed with a GPS simulator that is able to emulate GPS satellite signals and includes the NMEA-0183 protocol and RS232C communication standards. Furthermore, using the SKUD, the HMI of the real commercial CNS could be investigated with driver workload assessment methods.     

License plate location method unaffected by variation in size and aspect ratio

License plate location is a challenging task that is necessary for automatic vehicle identification. This paper presents a new method for locating a license plate when its size and aspect ratio are highly variable. The proposed method begins with an assumption that a license plate exists in a region where dense edges are located. We define an edge region as an area containing rich edges. The edge regions are created by dilating vertical edges, and they are classified into one of four types: left fragment type, right fragment type, whole type, and undefined type. The candidates for a license plate region are constructed by merging edge regions. Knowing what type of edge region is being examined is useful in the merging process. Finally, we verify whether each candidate contains a license plate or not by using the character arrangement information. The arrangement pattern is determined by the size of connected components and by the vertical overlap or horizontal distance between two neighboring components. Experimental results show that the proposed method gives robust results regardless of any variation in the size and aspect ratio of license plates.     

沥青混合料烟雾与材料力学性能之间的关系

着重于研究热拌沥青混合料生产过程中产生的烟雾与沥青力学性能之间的关系,涉及的影响因素有温度、沥青种类以及一些动力学参数。研究者在试验室拌和机上安装了气体取样设备,能够在正常拌和的同时对热拌沥青混合料烟雾中的多环芳香烃(PAH)以及有机化合物(TOC)进行取样分析。通过对沥青材料进行室内性能指标的测试,发现在所有指标中回收沥青的复合模量与沥青烟雾排放量的相关性最好,因为它的结果同时反映了材料的物理性能以及沥青氧化和老化的程度。同时还建立了热拌沥青混合料烟雾排放与拌和参数以及混合料力学性能之间的关系。     

车速变化对车辆操纵稳定性的影响(英文)

为了降低车速变化对车辆操纵稳定性的影响,建立了考虑车速变化的动态车辆转向运动模型,分析了描述模型的微分方程组所有系数都是随车速变化而时变的特性,通过变参数动态仿真,定量研究了车速变化对车辆操纵稳定性的影响.研究结果表明:减速时正的纵向车辆惯性力使后轴负荷向前轴转移,导致前轴侧偏刚度变大,后轴侧偏刚度变小,进而使车辆的横摆角速度增益增大,即车辆操纵稳定性变差;初始车速越高,减速度越大,车辆横摆角速度增益增大越快;加速时负的纵向车辆惯性力使前轴负荷向后轴转移,导致前轴侧偏刚度变小,后轴侧偏刚度变大,进而使车辆的横摆角速度增益减小.可见,减小车辆减速度、降低车身质心高度及增大轴距是弱化减速导致车辆操纵稳定性急剧变差的有效方法.