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In the context of off-road vehicle simulations, deformable terrain models mostly fall into three categories: simple visualization of the deformed terrain only, use of empirical relationships for the deformation, or finite/discrete element approaches for the terrain. A real-time vehicle dynamics simulation with a physics-based tire model (brush, ring or beam-based models) requires a terrain model that accurately reflects the deformation and response of the soil to all possible inputs of the tire in order to correctly simulate the response of the vehicle. The real-time requirement makes complex finite/discrete element approaches unfeasible, and the use of a ring or beam -based tire model excludes purely empirical terrain models. We present the development of a three-dimensional vehicle/terrain interaction model which is comprised of a tire and deformable terrain model to be used with a real-time vehicle dynamics simulator.

The objective of this paper is to delineate the importance of pictures, i.e., graphical models, in documenting and communicating the high level functionality of a complex system, primarily for embedded software requirements and specifications. An overview is given of various graphical techniques and methodologies for modeling complex systems. The aspects (advantages and disadvantages) relating to different categories of modeling are outlined. Discussion of complex systems extends beyond the functional/software aspects of product design to both process and project modeling. The author shares personal observations and experiences with modeling, and tools used.

While long-range planning is important to any organization, because of the constant turnover of volunteer leaders, a long-range strategic plan is crucial for maintaining continuity in a non-profit organization. SAE's strategic planning process resulted in a plan, evaluated and revised annually, which outlines the purpose, missions, and goals of the Society and describes action plans and steps necessary to achieve those goals. SAE's exceptional growth in all areas during the last ten years-for example, membership has grown from 37,000 in 1980 to 58,000 today-is evidence of the success of the process and the plan.

Braking energy recovery can significantly contribute to fuel economy and emission reduction, particularly for commercial vehicles driving in urban environment. By using the compressed air storage, rather than expensive and vulnerable batteries, this paper proposes a pneumatic hybrid system with an integrated compressor/expander unit (CEU) for commercial vehicles, in order to achieve stop/start function and braking energy recovery. During braking, the compressed air is recovered by CEU working in compressor mode and is charged to the air tanks. When the vehicle starts from stop, the CEU works as an expander to crank the engine with compressed air. The compressed air can also be used to supply the air tank of brake boost system, thus reducing its energy consumption. The mathematical models of energy conversion units, including the two modes of CEU and the air brake system, are established and analyzed.

By coupling a Personal Computer to process 1/0 hardware and adding realtime multitasking software, a low cost automated data acquisition and control system can be assembled. This paper describes such a system built in a 19 inch rack on wheels which has been used for diesel engine testing. The system is readily reprogrammable to customize the function of the system to the job at hand.

Overturning on a road turn has always been a problem in vehicles. Based on a half- vehicle model, the results of vehicle stability after incorporating a hydraulic-actuator system is analyzed. It has been shown in the paper that the stability of a vehicle on a road turn can be increased promisingly by tilting its body towards the inner direction. The results are compared with the corresponding results of a conventional vehicle. Because of the feasibility and effectiveness of the proposed algorithm, the above system shows a definite improvement in vehicle stability.

In today's vehicle, the electrical power distribution panel becomes the circuit protection, relay, and wire management center for the entire electrical system. This paper describes a new 3-D electrical distribution concept and presents a supporting design. The proposed design establishes circuits for connecting power inputs, outputs, and top loaded pluggable components by modifying a standardized flat conductive grid. The grid includes a repeating pattern of connecting rings and radial spokes. These spokes define circuit paths extending from and interconnecting each ring. At the final stages of manufacturing, the required circuit paths are created on a single sheet by selectively removing certain spokes. Multiple sheets are stacked with insulating barriers located between each layer. An interconnection between layers is realized by selectively positioning connecting pins through the ring nodes and interconnecting circuits defined on successive layers.

Recent innovative drives in hydraulics could introduce very competitive hybrid hydraulic vehicles (HHV). These drives has been considered and analyzed only in the serial HHV architecture. The series-parallel transmission architecture, also called power-split or e-CVT is highlighted as the most popular concept for full (strong) hybrid electric vehicles (HEV). The examples are one-mode power-split in Toyota Prius and two-mode (compound) power-split in GM-Allison EVT. Ambitions to make the hybrid hydraulic power trains better and more efficient would certainly require deeper analysis of more complex power-split (series-parallel) HHV transmission structures and related optimal controls. This paper presents bond graph based mathematical model of kinematics of a one-mode and a two-mode power-split hybrid hydraulic vehicle transmissions which are based on their hybrid electrical counterpart.

As a result of the introduction of the modern tilt cab, suspension designs are required to be more sophistocated in order to provide the ride quality expected from a modern truck. The purpose of the study undertaken was to determine practical methods and the respective considerations and decisions required to mount a cab to various chassis constructions. The basis of this exercise was a European type truck of cab over configuration. Various stages in the concept are highlighted in addition to relative decisions and required considerations. Because measurable standards exist on ride quality, this aspect was studied briefly due to the fact that generally required comfort standards vary a great deal between countries. The final objective was to determine the cab structural damage incurred through the cab suspension, and to determine projected vehicle mileages on various highways before structural damage is caused.

Compacted Graphite Iron (CGI) has been recognized for years as a unique material possessing a fortunate combination of properties intermediate between gray iron and ductile iron. This material, for reasons outlined in this paper, is ideal for cylinder blocks, heads and other cast iron components for diesel engines. It makes possible casting weight savings of up to 1/3 and/or increased power output. This paper will outline reasons why this is now possible, whereas it has seldom been applied in volume production heretofore. Physical and mechanical properties of CGI, which provide the opportunity for weight reduction and increased power, are discussed. Currently, most diesel engine cylinder blocks, heads, liners and many other castings are produced from gray iron, which requires relatively heavy sections to provide the strength, stiffness and durability necessary for commercial application.

In July, 1992 The Environmental Protection Agency (EPA) issued its final rule of section 604 of the Clean Air Act Amendments of 1990. The rule limits the usage, production and servicing of air-conditioning systems using CFC-12 (R-12) and HCFC-22 (R-22) refrigerants. The purpose of this action is to limit the deterioration of the stratospheric ozone layer. The reduction of the ozone allows ultraviolet radiation, type-B (UV-B), to penetrate and project down onto the earth. The act will affect the fleet operator in ways that may not have yet been explored. Specifically, operators will be faced with spending thousands of dollars on technology, as an industry and as individuals, to facilitate the necessary air-conditioning system conversions to provide compliance with the law and comfort for passengers. The need to develop an acceptable R-12 retrofit program has become a reality. This paper will outline the techniques for a successful R-12 to R-134a refrigerant conversion.

A new industrial vision system separates the function of application program development from on-line operation. A Vision Development System (VDS) is equipped with facilities designed to simplify and accelerate the complimentary but lower cost Target Application System (TASK) runs the application program developed with the VDS. This concept is described in an actual manufacturing application. Each stage of development and implementation is explored, including: 1. Defining the Requirements 2. Matching the Application to the Vision System 3. Developing the Application Software 4. Building and Installing the Vision System Application developed with a VDS experience lower development costs than conventional vision systems. Since the TASK processor is not burdened with development tools, it can be installed at a lower cost than comparable “Universal” vision systems.

The high gravity center of the concrete mixer truck reduces the truck’s stability while steering. The rolling stirring tank makes the stability even worse than the regular engineering vehicle due to the dynamic variation of the centroid position. Most of the researches on the rollover stability of concrete mixer trucks focus on the rollover model establishment and dynamic simulation module. The change of concrete centroid is ignored when the safety cornering speed is calculated. This paper proposes a pre-warning method for the cornering speed of concrete mixer trucks based on centroid dynamic simulation. In the method, the mixing tank stirring model and the vehicle driving dynamic model are established on the Fluent and TruckSim simulation platforms, respectively. The theoretical speed threshold obtained by simulation is used as the evaluation index of the warning speed in the curve. Firstly, the dynamic simulation of the stirring tank model is carried out by Fluent.

Fuel cell engines are expected to deliver greater efficiency and lower emissions than conventional transit bus powertrains in the near future. Although experimental vehicles have demonstrated the emission and efficiency benefits of fuel cell power, the next step toward implementation is widespread fleet demonstrations to prove the technology in the field. In order to aid in the start of new demonstrations and speed fuel cell technology towards the fleet vehicle marketplace, an assessment of the needs, risks, and advantages of using fuel cell power must be obtained from a consumer perspective. It has been assumed that the increased fuel efficiency that is inherent to fuel cell systems will lower operating costs as compared with conventional diesel powertrains. A comparison of two fuel cell buses and a diesel bus was completed in order to quantify the operational cost benefits and identify potential cost deterrents to fuel cell bus implementation.

This paper presents a preliminary study to estimate, using on-road and laboratory tests, the mileage range of liquefied petroleum gas (LPG) as an alternative fuel for diesel-fed public utility jeepneys in the Philippines. Data from the study would be used by the Philippine Department of Energy to formulate and implement alternative fuel programs for public transport. On-road fuel consumption, load factor, and GPS speed data from selected in-use LPG and diesel jeepneys plying a chosen urban route were gathered to develop corresponding drive cycles for chassis dynamometer testing at 100% load factor were conducted to estimate an upper limit for fuel consumption. Measured on-road diesel jeepney mileage was about 6.7 km/liter at 63.5% load factor while that for LPG jeepney was 3.8-4.2 km/liter at 59.8% load factor. Drive cycle tests yielded 5.2 km/liter for diesel and 2.6-3.1 km/liter for LPG.

This research was to model a 6×4 tractor-trailer rig using TruckSim and simulate severe braking maneuvers with hardware in the loop and software in the loop simulations. For the hardware in the loop simulation (HIL), the tractor model was integrated with a 4s4m anti-lock braking system (ABS) and straight line braking tests were conducted. In developing the model, over 100 vehicle parameters were acquired from a real production tractor and entered into TruckSim. For the HIL simulation, the hardware consisted of a 4s4m ABS braking system with six brake chambers, four modulators, a treadle and an electronic control unit (ECU). A dSPACE simulator was used as the “interface” between the TruckSim computer model and the hardware.

For years, producers of low to medium volume products of high unit cost have been faced with the questions-“How much do we test?” and “What if we don't?” Today, manufacturers cannot compete in the market if these questions are not answered. This paper presents a methodology for answering these questions quantitatively. It applies Bayes Theorem of “apriori knowledge” to generate a probabalistic model of the new product testing task. It uses the existing knowledge and expertise within the organization and a simple matrix technique to determine the testing needs for the project at hand. This paper is intended to address the issues of durability and reliability of new products that are manufactured in relatively low volumes, such as Lift Trucks and Farm Equipment and/or products of high unit cost such as construction or off highway machinery.

Transportation in the second half of this century tends towards employing large vehicles that offer cheap freights. Tied up to their century-old gauges, the railroads are the only exception. In Argentina, highway and railroad infrastructures mainly converge to fluvial ports which, owing to their lack of depth, cannot take in present-day vessels. This paper describes a fast wide-gauge train, which cannot be derailed or overturned; it shall enjoy a cheap t/km freight, cheaper than that of current trucks and trains, and even of river and ocean-going ships. It shall unite the North and South regions of Argentina as one backbone, and shall behave like a vast river or inland channel, linking it up with the Patagonian deep-sea ports, integrating and developing the country, which will cause its products to be competitive all over the world.

Increased responsibility is currently being placed on vehicle component manufacturers to certify products as an integral part of sub-system assemblies. In the guest for quality, the current trend in structural fatigue testing is to evaluate the performance of assemblies using tests which more closely simulate the actual part orientation and loading conditions. This dictates multidimension test systems with real time system performance. This paper presents a machine that can be used to apply multi-axial loads to bushings normally used in vehicle control arm assemblies. Several unique features of the mechanical aspect of the test system are explained and several different control schemes are presented.

This paper describes a practical and efficient approach for determining complete transient, as well as steady state response of tractor-trailer air brake systems by recording pushrod displacement and air brake service line pressure as a function to time. The test hardware utilizes easy to fabricate “clip on” transducers to measure pushrod stroke length. Data acquisition is via LABVIEW‚. All transducers are easy to temporarily affix to any tractor- trailer and require no alteration to the vehicle. A complete system check takes less time than manually measuring pushrod stroke as required under FMCSA. This system with one treadle application and release gives digital timing and displacement history of all brakes. Useful information includes: application and release profiles (pushrod velocity), shoe compliance upon seating and crack pressure release points for both tractor and trailer relay valves.