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Several configurations of truck tractor sleeper cabs were tested and modeled to investigate the potential to reduce heating and cooling loads. Two trucks were tested outdoors and a third was used as a control. Data from the testing were used to validate a computational fluid dynamics (CFD) model and this model was used to predict reductions in cooling loads during daytime rest periods. The test configurations included the application of standard-equipped sleeper privacy curtain and window shades, an optional insulated or arctic sleeper curtain, and insulated window coverings. The standard curtain reduced sleeper area heating load by 21% in one test truck, while the arctic curtain decreased it by 26%. Insulated window coverings reduced the heating load by 16% in the other test truck and lowered daytime solar temperature gain by 8°C. The lowered temperature resulted in a predicted 34% reduction in cooling load from the model.

SAE Recommended Practice J941 describes the eyellipse, a statistical representation of driver eye locations, that is used to facilitate design decisions regarding vehicle interiors, including the display locations, mirror placement, and headspace requirements. Eye-position data collected recently at University of Michigan Transportation Research Institute (UMTRI) suggest that the SAE J941 practice could be improved. SAE J941 currently uses the SgRP location, seat-track travel (L23), and design seatback angle (L40) as inputs to the eyellipse model. However, UMTRI data show that the characteristics of empirical eyellipses can be predicted more accurately using seat height, steering-wheel position, and seat-track rise. A series of UMTRI studies collected eye-location data from groups of 50 to 120 drivers with statures spanning over 97 percent of the U.S. population. Data were collected in thirty-three vehicles that represent a wide range of vehicle geometry.

The ease of getting into and out of passenger cars and light trucks is a critical component of customer acceptance and product differentiation. In commercial vehicles, the health and safety of drivers is affected by the design of the steps and handholds they use to get into and out of the cab. Ingress/egress assessment appears to represent a substantial application opportunity for digital human models. The complexity of the design space and the range of possible biomechanical and subjective measures of interest mean that developing useful empirical models is difficult, requiring large-scale subject testing with physical mockups. Yet, ingress and egress motions are complex and strongly affected by the geometric constraints and driver attributes, posing substantial challenges in creating meaningful simulations using figure models.

This study outlines a protocol for image data collection acquired from human volunteers. The data set will serve as the foundation of a consolidated effort to develop the next generation full-body Finite Element Analysis (FEA) models for injury prediction and prevention. The geometry of these models will be based off the anatomy of four individuals meeting extensive prescreening requirements and representing the 5th and 50th percentile female, and the 50th and 95th percentile male. Target values for anthropometry are determined by literature sources. Because of the relative strengths of various modalities commonly in use today in the clinical and engineering worlds, a multi-modality approach is outlined. This approach involves the use of Computed Tomography (CT), upright and closed-bore Magnetic Resonance Imaging (MRI), and external anthropometric measurements.

In this paper, interior noise of a heavy commercial truck was modeled with the room equation. This approach assumed that large truck cabins may be adequately modeled as a practical room as is done in architectural acoustics, where ray theory and statistical concepts are suitable, and where application of complicated wave theory may not be necessary. This simplifies computational requirements, making a semi-empirical scheme useful for timely product development. This study employed sound power measurements at thirty-four surface patches encompassing the interior cabin boundary. Each surface-patch constituted an individual interior noise source. Predicted and measured results correlated well, demonstrating the capability to estimate driver-position noise level from predicted periphery sound intensity changes.

The primary function of a gauge and information display cluster is to report to the driver the current state of the different systems of the vehicle and particularly to report out of range performance conditions. This paper will examine one implementation of the instrument cluster as a node on the J1939 data link as it relates to that functionality. Traditionally clusters have received their information from a variety of sensors requiring a substantial number of connections. Once the cluster is installed in the vehicle, changing the configuration may only be accomplished by means of a hardware change.

The increasing complexity of the electrical and electronic systems on trucks requires a more sophisticated electrical control system. Replacing many of the discrete electronic controls and wiring with a central Electrical System Controller (ESC) allows for easier integration of system components and improved system response. The use of software control within the Electrical System Controller, provides opportunities for enhanced system capabilities and a fluid platform for future development. This paper examines the software architecture employed within an Electrical System Controller and also examines the factors that govern the software's design. These include a requirement for the ESC to be highly configurable to accommodate a variety of features desired by customers.

Engineering tests that do not impact business decisions waste time, budgets and morale. This paper will consider input and output information for the test process-specifically in vehicle dynamics and structural integrity labs. Uncontrolled test processes are unlikely to fulfill expectations. Conversely, the process may be closely defined in a widespread specification, and yet not answer the question at hand. Potential downstream impacts of loosely defined technical details will be discussed. Topics include selection of transducers, recording parameters, filtering and analysis techniques. Physics of common environmental loading are presented, along with implications for both the test plan and later use of the test data. Case studies as both a truck, bus and railroad test services provider and consumer will be discussed.

The increased use of power field-effect transistors instead of power relays for controlling electrical loads on vehicles has created an opportunity for the development of a software based virtual fuse. This development has several important aspects to the vehicle OEM. Not only will the cost of the fuse be saved along with the cost of the fuse holder, but also perhaps the largest cost associated with using a traditional fuse: the wiring to and from the fuse. In commercial vehicles, the variability of one vehicle to the next may force different circuits to occupy the same physical space on the different vehicles. These differing circuits may also require different values of fuse elements. Ensuring that the correct fuse value is installed under these conditions can be a difficult task at best. Having a software based virtual fuse that can be programmed to match the vehicle configuration can eliminate having an unprotected circuit due to an assembly error.

The National Highway Traffic Safety Administration and the University of Michigan Transportation Institute are investigating truck design countermeasures to provide safety benefits during collisions with light vehicles. The goal is to identify approaches that would best balance costs and benefits. This paper outlines the first phase of this study, an analysis of two-vehicle, truck/light vehicle crashes from 1996 through 1998 using several crash data bases to obtain a current description and determine the scope of the aggressivity problem. Truck fronts account for 60% of light vehicle fatalities in collisions with trucks. Collision with the front of a truck carries the highest probability of fatal (K) or incapacitating (A) injury. Truck sides account for about the same number of K and A-injuries combined as truck fronts, though injury probability is substantially lower than in crashes involving the front of a truck.

With the added complexity of vehicle multiplexed systems, the task of accurately diagnosing vehicle electrical failures is daunting at best. Integration of smart controllers into the electrical system provide the added flexibility and capability of detecting and monitoring operating conditions. This paper discusses one approach to detecting and displaying vehicle electrical diagnostic information either directly to the driver/technician via on-board driver information systems or indirectly via off-board service tools.

Increasingly, manufacturers are looking to computer simulation methods to accurately assess ride quality potential of new vehicle designs as they are being developed. This requires detailed multi-body dynamic models to be developed with sufficient fidelity to replicate ride relevant phenomenon. These models must have the capability to: Represent the distributed mass and elasticity of the vehicle structures (e.g. frame ladder, cab, and trailer). Include the non-linear behavior of shock absorbers and elastomeric components. Reproduce the fundamental system dynamics that influence ride. Provide output of the acceleration, velocity, and displacement measures needed to compute ride quality. This paper discusses the development of an ADAMS multi-body dynamic model of a tractor semi-trailer for use as a predictive tool in evaluating ride quality design improvements.

This paper will review and discuss the advantages and disadvantages of utilizing modular systems in vehicle assembly, particularly Medium Duty, Severe Service, and Heavy Duty trucks. Focus will be put on cab interior modules, as they were developed for the International 4000, 7000, and 8000 series trucks. For the purposes of this paper, “system” or “system module” refers to an assembly of components that can wholly or substantially perform its design function as a stand-alone unit. An example would be a vehicle seat assembly. A completed seat can perform its intended function sitting on the plant floor, as well as in the vehicle. The impacts of the system module design approach on assembly processing, manufacturing complexity, reliability and quality, and design and validation will be discussed. Various levels of system modularity have been successfully used in recent years in many types of vehicle manufacturing, particularly in the automotive industry.

Workflow automation is a revolutionary technology that dramatically improves office business processes. This paper is a case study of how workflow was introduced into the Truck Design and Technical Center of International Truck and Engine Corporation. Some results and lessons learned are offered.

The test strategy, test design and test case development for a ‘to order’ configuration system for a configurable electronic control system for a heavy-duty vehicle are discussed. The issues in test case design, to maximize test coverage for a highly combinatoric configuration capability, are reviewed. Then, the role played by the Electronics Integration Test Station [EITS] to evaluate test items as an element of test case design and conducting the tests is reviewed. EITS provides a hardware-in-the-loop test facility for evaluating vehicle electronic control systems. Finally, the coverage achieved is compared with the coverage required as determined by analysis of the order content of vehicles and the analysis of the configurable electronic control system design information.

The methods used to cope with the simultaneous development of the Electronics Integration Test Station (EITS) hardware and software in conjunction with its Test Target hardware and software are reviewed. The EITS provides a system level test facility for conducting hardware-in-the-loop (HIL) evaluations on vehicle electronic control systems. The development methods feature, formal hardware and software requirements documentation, formal software development, an iterative build process, and electronic capture of test incidents for analysis, verification and problem resolution. The application of the software development environment including the requirements management tools, and object oriented design tools is discussed within the context of the development methodology.

The system level requirements for the Electronics Integration Test Station (EITS) are reviewed. EITS provides capabilities for system level testing of a variety of heavy-duty vehicle electronic control module configurations. EITS provides a hardware-in-the-loop (HIL) test facility at the system level, permitting the development of integration experiments as individual control system modules are added to the complement of modules being tested. The evaluation needs, which drive system-level testing of control system performance for systems of heavy-duty vehicle electronic control modules, are discussed. Implementation issues leading to system level requirements are also discussed.

Effective application of human figure models to truck interior design requires accurate data on the postures and positions of truck drivers. Errors in positioning of figure models propagate to errors in reach, visibility, and other analyses. This paper describes methods used in a recent study to measure in-vehicle driving postures in Class 6, 7, and 8 trucks. A three-dimensional coordinate measurement machine was used to measure body landmark locations after a driver completed a short road course. The data were used to validate posture-prediction models developed in a previous laboratory study. Vehicle calibration, driver selection, and testing methods are reviewed.

Propagation of vehicle interior noise may be discovered through experimental or analytical methods. This study demonstrates a new MATLAB™ application, where detailed acoustic distributions are determined and displayed from limited measurements. In particular, this method renders energy emanating from a commercial truck dash panel. Results show discernable surface details with a blanket contour plot. The contour mesh comprised of linearly-interpolated values from a small number of discrete measurements. Qualitative and quantitative conclusions were easily made from this interpolation, including relative acoustic leakage and radiation concerns - demonstrated by near-field sound intensity.

This paper discusses an analytical tool that has been developed to predict what types of interior sound package treatments may be necessary in a truck cab to meet a predetermined target sound level at the driver location. The steps that were taken to develop this tool involved a combination of experimental measurement and analytical based studies. Measurements were conducted to identify the acoustic strengths of the major noise paths through which sound travels from outside to inside the truck. These findings were then used to develop a sound package that reduced the vehicle interior noise to meet the target. Measurements were primarily made on a chassis roll dynamometer with final road verification to substantiate the dynamometer data. Data obtained from these measurements were also used in the analytical model that predicts the impact of various acoustics parts in the vehicle, and has the capability to optimize the sound package treatment in the vehicle.