Characterization of driving patterns and development of a driving cycle in a military area

This study develops a gradient-sensitive driving cycle for vehicles in military areas with paved and unpaved roads over steep and undulating terrain. The methodology develops the driving cycle using micro-trips extracted from real-world data taking into account factors that affect fuel consumption. The accuracy of cycle depended on the root mean square error and information value.     

Field tests for evaluating cooperative intersection signal violation warning system (CISVWS)

This paper demonstrates the results of field tests for assessing a cooperative intersection signal violation warning system (CISVWS), which consists of (a) hardware, including an in-vehicle warning device, roadside antenna, and traffic signal controller, and (b) software to operate and test the cooperative system through vehicle to infrastructure (V2I) communication systems. Field tests were performed under real traffic situations in order to test the system in terms of the initiation time of the signal violation warning from the signal controller, the activation and duration of on board equipment (OBE), and the warning delay based on the relationships between distance variables, including the safe stopping distance, and the location of road side equipment (RSE). Findings from the field test at the real-world signalized intersection sites indicated that the system would be capable of reducing red light violations and intersection collisions through use of the in-vehicle warning device at signalized intersections.     

A real-time multi-vehicle simulator for longitudinal controller design

This paper presents a new multi-vehicle simulator for platoon simulation. The main new feature of the developed simulator is a network structure for the real-time simulation of multiple vehicles, each with a detailed powertrain and engine model. It has a small initial delay, which is determined by the number of connected PCs, but the actual simulation is performed and displayed in real-time after this initial and one-time delay. Several longitudinal controllers, including a PID controller with gain scheduling, an adaptive controller, and a fuzzy controller, are also implemented in the simulator. Various system parameters can be modified interactively in the simulator screen, which is very useful for simulating a platoon of heterogeneous vehicles, in which vehicles with different dynamics and different longitudinal controllers may be involved. The simulator provides an excellent tool to develop vehicle longitudinal controllers and to study platoon behaviors. The developed simulator is also effective in testing the effects of nonlinearities neglected in the controller design phase, such as actuator delays and gear shifting schedule.     

Model-based fault detection and isolation in automotive yaw moment control system

This paper presents a model-based fault detection and isolation technique for automotive yaw moment control system. For this purpose, a novel fault detection and isolation algorithm for a class of actuator-plant systems is proposed. Compared with the existing fault detection and isolation techniques that can only isolate a target fault or require multiple observers to isolate multiple faults, a unique strength of the proposed algorithm is its ability to isolate faults at the component level solely based on the residuals generated by a single observer. The validity of the proposed algorithm, applied to automotive yaw moment control system, is investigated via a simulation study based on a realistic vehicle dynamics model. The results suggest that the proposed algorithm can isolate the component subject to fault while effectively handling two perennial nuisances: sensitivity to disturbances and false alarms due to uncertainties.     

Enhancement of aerodynamic performance through high pressure relief in the engine room for passenger car using cfd technique

High pressure acting on the vehicle’s body plays an important role in deciding the aerodynamic drag. An idea has been suggested to enhance the aerodynamic performance for small passenger car by relieving the high pressure in the engine room. The high pressure inside the engine room can be released to the outside of the vehicle through a hole perforated on the wheel house liner. About 1 % of the drag coefficient can be improved with the 1.88 % of the radiator air mass flow rate increment by installing the top hole with slots on the wheel house liner. Flow simulations are performed at the driving velocity of 110 km/h with the moving wall condition of the same velocity. The tire is rotating to catch more precise flow physics around a tire and wheelhouse liner.     

A New Method for Accurately Estimating the Weight of Moving Vehicles Using Piezoelectric Sensors and Adaptive-footprint Tire Model

Summary This paper presents new methods for estimating the axle weight of a moving vehicle, using two piezoelectric sensors and adaptive-footprint tire model. It is more difficult to weigh vehicles in motion accurately than to weigh standing vehicles. The difficulties in weighing moving vehicles result from sensor limitations as well as dynamic loading effects induced by vehicle/pavement interactions. For example, two identical vehicles with the same weight will generate sensor signals that differ in the shape and the peak value, depending the tire pressure, vehicle speed, road roughness, and sensor characteristics. This paper develops a method that is much less sensitive to these variable factors in determining the axle weight of a moving vehicle. In the developed method, first the piezoelectric sensor signal is reconstructed using the inverse dynamics of a high-pass filter representing the piezoelectric sensor. Then, the reconstructed signal, is normalized, using the nominal road/tire contact length obtained using an adaptive-footprint tire model, and then integrated. Experiments are performed with 3 vehicles of known weight ranging from 1,400 kg to 28,040 kg. The developed method is compared to two other algorithms. Results show that the developed method is most consistent and accurate.     

Coupled thermo-mechanical analysis and shape optimization for reducing uneven wear of brake pads

In vehicle braking systems, the non-uniform contact pressure distribution on the brake pad is a major cause of uneven wear. The experimental approach of the wear phenomenon is the time consuming and costly. For this reason, a threedimensional finite element (FE) model of a brake system is presented for numerical simulation in this paper. A coupled thermo-mechanical analysis is carried out to confirm the non-uniform contact pressure distribution. A correlation between the non-uniform contact pressure and uneven wear is confirmed by measuring the amount of wear in the brake pad. The shape optimization of the brake pad is performed to reduce the uneven wear. In addition, the simulation results, such as natural frequency and temperature, are compared to experimental results.     

Development of a new analytical model for a railway vehicle equipped with independently rotating wheels

The urban tram introduced recently has a low-floor structure for the convenience of passengers getting on and off. To adjust the low-floor level and improve performance on curves, most low-floor trams have IRWs (independently rotating wheels) with no central axle between the two wheels. Eliminating the central axle, however, creates several inherent problems, such as insufficient guiding force and excessive wear. To analyze these problems, a new analytical model is described in this paper to describe the dynamic characteristics of IRWs more precisely. This analytical model is developed to consider the effects of longitudinal creep in particular, which have been ignored in conventional analytical models of IRWs. In addition, a running stability analysis based on the newly developed analytical model is conducted to compare the critical speeds of IRW-axle vehicles and rigid-axle vehicles. The dynamic characteristics of an initial disturbance are compared to verify that the analytical model is effective in expressing the dynamic characteristics of IRWs.     

Combustion characteristics of LPG and biodiesel mixed fuel in two blending ratios under compression ignition in a constant volume chamber

This study aims to investigate the combustion characteristics of mixed fuel of liquefied propane gas (LPG) and biodiesel under compression ignition (CI) in an effort to develop highly efficient and environmentally friendly mixed fuelbased CI engines. Although LPG fuel is known to be eco-friendly due to its low CO₂ emission, LPG has not yet been widely applied for highly efficient CI engines because of its low cetane number and is usually mixed with other types of CI-friendly fuels. In this study, a number of experiments were prepared with a constant volume chamber (CVC) setup to understand the fundamental combustion characteristics of mixed fuel with LPG and biodiesel in two weight-based ratios and exhaust gas recirculation (EGR) conditions. The results from the current investigations verify the applicability of mixed fuel of LPG and biodiesel in CI engines with a carefully designed combustion control strategy that maximizes the benefits of the mixed fuel. Based on the results of this study, ignition is improved by increasing the cetane value by using higher blending ratios of biodiesel. As the blending ratios of biodiesel increased, CO and HC decreased and CO₂ and NO_x increases.     

Isrss: Integrated side/rear safety system

As driver assistant systems (DAS) and active safety vehicles (ASV) with various functions become popular, it is not uncommon for multiple systems to be installed on a vehicle. If each function uses its own sensors and processing unit, it will make installation difficult and raise the cost of the vehicle. As a countermeasure, research integrating multiple functions into a single system has been pursued and is expected to make installation easier, decrease power consumption, and reduce vehicle pricing. This paper proposes a novel side/rear safety system using only one scanning laser radar, which is installed in the rear corner of the driver’s side. Our proposed system, ISRSS (integrated side/rear safety system), integrates and implements four system functions: BSD (blind spot detection), RCWS (rear collision warning system), semi-automatic perpendicular parking, and semi-automatic parallel parking. BSD and RCWS, which operate while the vehicle is running, share a common signal processing result. The target position designation for perpendicular parking and parallel parking situations is based on the same signal processing. Furthermore, as system functions during running and those during automatic parking operate in exclusive situations, they can share common sensors and processing units efficiently. BSD and RCWS system functions were proved with 13025 and 2319 frames, respectively. The target position designation for perpendicular and parallel parking situations was evaluated with 112 and 52 situations and shows a success rate of 98.2% and 92.3%, respectively.