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In occupant sensing system development, the Anthropomorphic Test Dummy (ATD) and the Occupant Classification ATD (OCATD) are frequently used to simulate live human subjects in the testing and validation of weight based occupant sensing systems. A study was conducted to investigate the range of loading differences between these ATDs and live human subjects over various seating postures and conditions. The results of the study revealed that differences in seat load patterns could be significant, even though both the ATD and live humans are in the same weight and body size categories. Seat loading was measured using Hybrid III (5th percentile female, 50th percentile male, and 3 year old) ATDs, OCATDs (OCATD5 - 5th percentile female, and OCATD6 - 6 yr old child), and a CRABI (12-month old) dummy. Human subjects in the same weight and height categories as the above listed ATDs were also measured.

Close-coupled or manifold catalysts have been extensively employed to reduce emissions during cold start by achieving quick catalyst light-off. These catalysts must have good thermal durability, high intrinsic light-off activity and high HC/CO/NOx conversions at high temperature and flow conditions. A number of studies have been dedicated to engine control, manifold design and converter optimization to reduce cold start emissions. The current paper focuses on the effect of catalyst design parameters and their performance response to different engine operating conditions. Key design parameters such as catalyst formulation (CeO2 vs. non CeO2), precious metal loading and composition (Pd vs. Pd/Rh), washcoat loading, catalyst thermal mass, substrate properties and key application (in use) parameters such as catalyst aging, exhaust A/F ratio, A/F ratio modulation, exhaust temperature, temperature rise rate and exhaust flow rate were studied on engine dynamometers in a systematic manner.

The focus of this paper is to understand, from experimental data, the R134a refrigerant emission rates of various hose materials due to permeation. This paper focuses on four main points for hose assembly emission of R134a: (1) characteristics of hose permeation in response to the effect of oil in R134a and the characteristics of hose permeation of vapor vs. liquid refrigerant; (2) conditioning of the hose material over time to reach steady state R134a emission; (3) the relative contribution of hose permeation and coupling emission to the overall hose assembly refrigerant emission; (4) transient emission rates due to transient temperature and pressure conditions. Studies include hoses with different materials and constructions resulting in various levels of R134a permeation.

The intensity of a combustion flame ionization current signal (ionsense) can be used to monitor and control combustion in individual cylinders during a cold engine start. The rapid detection of poor or absence of combustion can be used to determine fuel delivery corrections that may prevent engine stalls. With the ionsense cold start control active, no start failures were recorded even when the initially (prior to ionsense correction) commanded fueling had failed to produce a combustible mixture. This new dimension in fuel control allows for leaner cold start calibrations that would still be robust against the possible use of low volatility gasoline. Consequently, when California Phase 2 fuel is used, cold start hydrocarbon emissions could be lowered without the risk of an engine stall if the appropriate fuel is replaced with a less volatile one.

A requirement of many modern safety-critical automotive applications is to provide failsafe operation. Several analysis methods are available to help confirm that automotive safety-critical systems are designed properly and operate as intended to prevent potential hazards from occurring in the event of system failures. One element of safety-critical system design is to help verify that the software and microcontroller are operating correctly. The task of incorporating failsafe capability within an embedded microcontroller design may be achieved via hardware or software techniques. This paper surveys software failsafe techniques that are available for application within a microcontroller design suitable for use with safety-critical automotive systems. Safety analysis techniques are discussed in terms of how to identify adequate failsafe coverage.

Segmented, Silicon-Carbide Diesel Particulate Filters appear to be automotive industry's popular choice for reducing particulate emissions of Diesel Engines, particularly for light duty platforms. Since flow resistance represents an important performance feature of a filter, it is important that reasonable prediction tools for such filters are developed for use in their development, design, applications and regeneration control. A model for predicting pressure drop of segmented filters is presented here: an existing, well-accepted pressure drop model for monolithic (non-segmented) filters is customized to one for a segmented filter using a ‘weighted number of inlet channels’ based on equivalent filtration wall area of a monolithic filter. Flow resistance data collected experimentally on segmented filters are used to demonstrate the accuracy of the new model.

Slush molding is a unique processing operation that was developed originally for polyvinyl chloride (PVC) based materials. It has been utilized to produce a variety of automotive interior products, including instrument panel skins, where relatively intricate designs are required. PVC becomes brittle upon aging, while thermoplastic polyolefin (TPO) doesn’t lose its ductility upon aging. TPOs have made significant inroads into interior applications in the form of thermoformed extruded sheet. However, when multiple grains, geometric (technical) grains, deep profile lettering, and logos are needed, slush molding is the preferred process. Currently, there is an increased demand for non-PVC slush moldable materials, such as TPO, that can meet these demanding aggressive styling requirements. The semi-crystalline nature of TPO compositions renders them more difficult to process than PVC in slush molding.

In this paper the effects of rear brake imprecision on vehicle braking performance and yaw dynamics are investigated for a vehicle with individually controlled brake actuators. The effects of side to side brake force imbalance on vehicle yaw rate and path deviation during straight line braking and in braking in turn maneuvers are examined through analysis, simulations and vehicle testing. These effects are compared to the influences of disturbances encountered during normal driving such as side winds and bank angles of the road. The loss of brake efficiency due to imprecision in generating actuating force is evaluated for different types of vehicles and different levels of vehicle deceleration. Requirements regarding path deviation during straight line braking and braking efficiency on low friction surfaces were found to lead to the most stringent specifications for actuator accuracy in realizing the desired braking forces.

In dynamic rollover tests many vehicles experience sustained body roll oscillations during a portion of road edge recovery maneuver, in which constant steering angle is maintained. In this paper, qualitative explanation of this phenomenon is given and it is analyzed using simplified models. It is found that the primary root cause of these oscillations is coupling occurring between the vehicle roll, heave and subsequently yaw modes resulting from suspension jacking forces. These forces cause vertical (heave) motions of vehicle body, which in turn affect tire normal and subsequently lateral forces, influencing yaw response of vehicle. As a result, sustained roll, heave and yaw oscillations occur during essentially a steady-state portion of maneuver. Analysis and simulations are used to assess the influence of several chassis characteristics on the self-excited oscillations. The results provide important insights, which may influence suspension design.

This paper proposes the concept of Generalized Diagnostic Component (GDC) and presents a modular fault diagnostic strategy for safety critical automotive systems. The diagnostic strategy makes full use of hierarchical techniques, integrates the generalized diagnostic design into all-purpose vehicle diagnoses based on reconfiguration of the GDCs, and inherits the model-based diagnostic algorithms developed for Steering/Braking-By-Wire systems. The GDC-based approach simplifies the design and integration of diagnostics in complex dynamical control systems, and has been successfully implemented in an eight degrees of freedom NAVDyn (Non-Linear Analysis of Vehicle Dynamics) simulation model using Matlab Simulink. The simulation results are provided in this paper to testify that the diagnostic strategy and implementation are feasible, efficient and dependable.

A RTD (resistive temperature device) high temperature sensor was developed for exhaust gas temperature measurement. Extensive modeling and optimization was used to supplement testing in development. The sensor was developed to be capable of withstanding harsh environments (-40° to 1000°C), typical of engine applications, including poisons, while maintaining high accuracy (< 0.5% drift after 500 hrs of aging at 950°C). The following sensor characteristics are presented: resistance-temperature curve, accuracy, response time, and long-term durability. In addition, a system error analysis program was developed with representative results.

With the requirements for reducing the emissions and improving the fuel economy, the automotive companies are developing hybrid, 42 V and fuel cell vehicles. Power electronics is an enabling technology for the development of environmental friendly vehicles, and to implement the various vehicle electrical architectures to obtain the best performance. In this paper, the requirements of the power semiconductor devices and the criteria for selecting the power devices for various types of low emission vehicles are presented. A comparative study of the most commonly used power devices is presented. A brief review of the future power devices that would enhance the performance of the automotive power conversion systems is also presented.

The University of Wisconsin - Madison hybrid vehicle team has designed and constructed a four-wheel drive, charge sustaining, parallel hybrid-electric sport utility vehicle for entry into the FutureTruck 2003 competition. This is a multi-year project utilizing a 2002 4.0 liter Ford Explorer as the base vehicle. Wisconsin's FutureTruck, nicknamed the ‘Moolander’, weighs 2000 kg and includes a prototype aluminum frame. The Moolander uses a high efficiency, 1.8 liter, common rail, turbo-charged, compression ignition direct injection (CIDI) engine supplying 85 kW of peak power and an AC induction motor that provides an additional 60 kW of peak power. The 145 kW hybrid drivetrain will out-accelerate the stock V6 powertrain while producing similar emissions and drastically reducing fuel consumption. The PNGV Systems Analysis Toolkit (PSAT) model predicts a Federal Testing Procedure (FTP) combined driving cycle fuel economy of 16.05 km/L (37.8 mpg).

A new single-brick Ba + alkali metals NOx-Trap catalyst has been developed to replace a two-brick NOx-Trap system containing a downstream three-way catalyst. Major development efforts include: 1) platinum group metals selection for higher HC oxidation with potassium-containing washcoat, 2) alumina and ceria selection, and Rh architecture design for more efficient NOx reduction and 3) NiO to suppress H2S odor. Mitsubishi Motors' 1.8L GDI™ with this Delphi new NOx-Trap catalyst with H2S control achieves J-LEV standard with less cost and lower backpressure compared to the previous model. It is further discovered that incorporation of NiO into the NOx-Trap washcoat is effective for H2S control during sulfur purge but has a negative impact on thermal durability and sulfur resistance. Further study to improve this trade-off has been made and preliminary results of an advanced washcoat design are presented in this paper. Details will be reported in a future publication.

A squeal analysis on a front disc brake is presented here utilizing the new complex eigenvalue capability in ABAQUS/Standard. As opposed to the direct matrix input approach that requires users to tailor the friction coupling matrix, this method uses nonlinear static analyses to calculate the friction coupling prior to the complex eigenvalue extraction. As a result, the effect of non-uniform contact pressure and other nonlinear effects are incorporated. Friction damping is used to reduce over-predictions and the velocity dependent friction coefficient is defined to contribute negative damping. Complex eigenvalue predictions of the example cases show very good correlation with test data for a wide range of frequencies. Finally, the participation of rotor tangential modes is also discussed.

A seat belt usability study was conducted to investigate factors associated with seat belt comfort and convenience related to shoulder belt contact pressure, shoulder belt fit, and seat belt upper anchorage location. Two major objectives were addressed in this study: (1) Determine the shift in the contact pressure while changing the seat back angle and seat belt attachment points / B-pillar location by utilizing a body pressure measurement system; (2) Identify how seat belt contact pressure and fit affect users' subjective feeling of comfort. Results from the statistical analysis shows that the seat belt contact pressure increases when the D-ring moves away from the driver in the fore-aft direction (X-axis) whereas height adjustment of the D-ring (Z-axis) is not statistically significant in terms of pressure distribution.

Regulatory and market pressures continue to challenge the automotive industry to develop technologies focused on reducing exhaust emissions and improving fuel economy. This paper introduces a practical model, which evaluates the economic value of various technologies based on their ability to reduce fuel consumption, improve emissions or provide consumer benefits such as improved performance. By evaluating the individual elements of economic value as viewed by the OEM manufacturer, while keeping the end consumer in mind, technology selection decisions can be made. These elements include annual fuel usage, vehicle performance, mass reduction and emissions, among others. The following technologies are discussed and evaluated: gasoline direct injection, variable valvetrain technologies, common-rail diesel and hybrid vehicles.