Performance measurements of a tracked vehicle system

To improve crossing ability, the most important performance factor for tracked vehicle systems operating on low-bearing capacity peats, and to minimize income losses that result from downtime and maintenance costs, a vehicle was designed in order to adapt to operating condition changes. This article describes the mobile performance of a novel vehicle with segmented rubber tracks on a low-bearing capacity peat. At an equivalent travelling speed, the novel vehicle’s tractive performance in a variable operating environment caused by changes in terrain cohesiveness and hydrodynamic responses was superior to that of the previous model. The new vehicle, which could be operated on the Sepang peat, showed a tractive effort of 42.2% of the gross vehicle weight in field experiments; the recommended minimum tractive effort is between 30 and 36% of the gross vehicle weight.     

Optimized fuzzy control strategy for a spa hybrid truck

In this paper, an optimized control strategy is proposed for a split parallel hydraulic hybrid truck. The model of the vehicle was simulated in Simulink. According to a global optimization technique, a fuzzy control strategy is developed for the vehicle. This strategy shows flexibility for different drive cycles and a desirable fuel consumption reduction, especially for a low speed drive cycle, which is extracted according to an urban utility vehicle mission.     

A simplified model for evaluating tire wear during conceptual design

In the field of vehicle dynamics, commercial software can aid the designer during the conceptual and detailed design phases. Simulations using these tools can quickly provide specific design metrics, such as yaw and lateral velocity, for standard maneuvers. However, it remains challenging to correlate these metrics with empirical quantities that depend on many external parameters and design specifications. This scenario is the case with tire wear, which depends on the frictional work developed by the tire-road contact. In this study, an approach is proposed to estimate the tire-road friction during steady-state longitudinal and cornering maneuvers. Using this approach, a qualitative formula for tire wear evaluation is developed, and conceptual design analyses of cornering maneuvers are performed using simplified vehicle models. The influence of some design parameters such as cornering stiffness, the distance between the axles, and the steer angle ratio between the steering axles for vehicles with two steering axles is evaluated. The proposed methodology allows the designer to predict tire wear using simplified vehicle models during the conceptual design phase.     

Decentralized neuro-fuzzy control for half car with semi-active suspension system

In this paper, a decentralized neuro-fuzzy controller has been created in order to improve the ride comfort and increase the stability for half car suspension system, which used the magneto-rheological damper as a semi-active device. Firstly, relative gain array and relative disturbance gain methods have been used for deriving a relation between inputs, disturbances and outputs to select pairing with minimum interaction to design a decentralize controller. Secondary, decentralized neuro-fuzzy controllers for front and rear chassis are designed to predict the required damping force taking the acceleration of the sprung mass and desired acceleration obtained by using pole-placement method as inputs. To predict the control voltage required for producing the force predicted by the controller, the inverse neuro-fuzzy model of MR damper has been designed. Simulation by using MATLAB programs has been created. The results show that the ride comforts and vehicle stability have been improved in comparison with the passive system.     

西藏复杂地质环境下路基加宽拼接方案试验研究

针对西藏某公路的加宽改造,提出了5种新旧路基加宽拼接方案。按这5种方案,共修筑了3段试验路。对试验路的设计原则、施工要求和工艺进行了讨论。通过试验数据,对各种拼接方案的效果进行了比较分析。结果表明,用5层双向土工格栅自路基顶面向下,以层间距30cm的加筋方式加强新旧路基间的结合是较好的路基加宽拼接方案。     

磁传感器阵列布置形式对铁磁目标磁场信息量获取的影响

为进行铁磁目标磁场的精确建模,利用磁传感器阵列测量了铁磁目标周围特定区域的磁场分布,根据测量数据重建铁磁目标的磁源分布,并以观测矩阵的奇异值坡度为评价标准对磁传感器阵列所获得的铁磁目标磁场信息量进行评估。通过将理想和简化布置形式下的磁传感器三分量阵列和垂直分量阵列进行对比分析,发现与垂直分量阵列相比,三分量阵列更具优势,而简化三分量阵列则因其具有可获得充分的磁场信息、能减少测量点数、占地最小等优点成为实际工程中最可取的阵列形式。     

Multivariate modeling of pedestrian fatality risk through on the spot accident investigation

Pedestrians are the most vulnerable users of public roads and represent one of the largest groups of road casualties; their death rate around the world due to vehicle-pedestrian collisions is high and tending to rise. In Spain, as in other countries of the European Union, steps have been taken to reduce the number and consequences of such accidents, with encouraging results in recent years. A key to countering this concern is the accident research activity that has obtained remarkable achievements in different fields, especially when multidisciplinary approaches are taken. This paper describes the development of a multivariate model that is able to detect the most influential parameters on the consequences of vehicle-pedestrian collision and to quantify their impact on pedestrian fatality risk. First, an accident database containing detailed information and parameters of vehicle-pedestrian collisions in Madrid has been developed. The accidents were investigated on the spot by INSIA accident investigation teams and analyzed using advanced reconstruction techniques. The model was then developed with two components: (1) a classification tree that characterizes and selects the explanatory variables, identifying their interactions, and (2) a binary logistic regression to quantify the influence of each variable and interaction resulting from the classification tree. The whole model represents an important tool for identifying, quantifying and predicting the potential impact of measures aimed at reducing injuries in vehicle-pedestrian collisions.     

Economic value and utility of a powertrain system for a plug-in parallel diesel hybrid electric bus

This research is the first to develop a design for a powertain system of a plug-in parallel diesel hybrid electric bus equipped with a continuously variable transmission (CVT) and presents a new design paradigm of the plug-in hybrid electric bus (HEB). The criteria and method for selecting and sizing powertrain components equipped in the plug-in HEB are presented. The plug-in HEB is designed to overcome the vulnerable limitations of driving range and performance of a purely electric vehicle (EV) and to improve fuel economy and exhaust emissions of conventional bus and conventional HEBs. The control strategy of the complicated connected propulsion system in the plug-in parallel HEB is one of the most significant factors in achieving higher fuel economy and lower exhaust emissions of the HEV. In this research, a new optimal control strategy concept is proposed against existing rule-based control strategies. The optimal powertrain control strategy is obtained through two steps of optimizations: tradeoff optimization for emission control and energy flow optimization based on the instantaneous optimization technique. The proposed powertrain control strategy has the flexibility to adapt to battery SOC, exhaust emission amount, classified driving pattern, driving condition, and engine temperature. The objective of the optimal control strategy is to optimize the fuel consumption, electricity use, and exhaust emissions proper to the performance targets. The proposed control strategy was simulated to prove its validity by using analysis simulation tool ADVISOR (advanced vehicle simulator).     

Effects of residual stresses on the static and fatigue strength of laser-welded lap joints with different welding speeds

This study was conducted to determine whether the different residual stresses caused by different welding speeds affect the static and fatigue strength of laser-welded lap joints. Residual stresses in STS301L laser-welded lap joints of different thicknesses under two laser-welding speed conditions, 4.1 m/min and 5.1 m/min, were evaluated with the incremental hole-drilling strain gage method at the middle of the heat-affected zone (HAZ). Then, static and fatigue tests were performed. The results show that higher static and fatigue strengths were obtained from the specimens welded with a 4.1 m/min welding speed than from the specimens welded at 5.1 m/min. The main difference was due to the compressive principal residual stress magnitude and its orientation near the HAZ. Also, the micro-hardness profile along the failure interface was measured to verify the static and fatigue failure behavior.     

Torsional stiffness and weight optimization of a real bus structure

In this paper, the structural optimization of a real bus structure is proposed. The proposed optimization has been accomplished by means of genetic algorithms. The structural behavior of the bus structure when subjected to weight and torsion was also analyzed using the finite element method (FEM). The results demonstrate that improved weight and torsional stiffness are achieved with the optimized structure.