Search Results

This study assessed a driver’s ability to safely manage Super Cruise lane changes, both driver commanded (Lane Change on Demand, LCoD) and system triggered Automatic Lane Changes (ALC). Data was gathered under naturalistic conditions on public roads in the Washington, D.C. area with 12 drivers each of whom were provided with a Super Cruise equipped study vehicle over a 10-day exposure period. Drivers were shown how to operate Super Cruise (e.g., system displays, how to activate and disengage, etc.) and provided opportunities to initiate and experience commanded lane changes (LCoD), including how to override the system. Overall, drivers experienced 698 attempted Super Cruise lane changes, 510 Automatic and 188 commanded LCoD lane changes with drivers experiencing an average of 43 Automatic lane changes and 16 LCoD lane changes.

The automotive seat has undergone significant advancements in technology due to changing customer demands, levels of autonomy and vehicle regulations. These advancements have presented both opportunities and challenges in creating a pleasant experience for customers by ensuring optimal seat comfort and a joyful human experience. Seats are always being built to accommodate different percentiles of occupant comfort requirements; original equipment manufacturers come up with various seating adjustment features. However, there is considerable variation among each percentile of occupants in how they utilize these features to achieve a comfortable seating position based on their unique preferences and circumstances. Additionally, there are variations in occupant postures due to the ways people have adapted their driving habits or styles when it comes to the way they sit.

Internal organ injuries of the chest are one of the leading causes of deaths in motor vehicle crashes. The issue of initial presence and dynamic formation of voids around the heart and aorta is addressed to improve kinematics, force interaction and injury risk assessment of these organs of the Global Human Body Model. Steps to fill the voids are presented.

Driver out-of-position (OOP) tests were developed to evaluate the risk of inflation induced injury when the occupant is close to the airbag module during deployment. The Hybrid III 5th percentile female Anthropomorphic Test Device (ATD) measures both sternum displacement and chest acceleration through a potentiometer and accelerometers, which can be used to calculate sternum compression rate. This paper documents a study evaluating the chest accelerometers to assess punch-out loading of the chest during this test configuration. The study included ATD mechanical loading and instrumentation review. Finite element analysis was conducted using a Hybrid III - 5th percentile female ATD correlated to testing. The correlated restraint model was utilized with a Hybrid III - 50th percentile male ATD. A 50th percentile male Global Human Body Model (HBM) was then applied for enhanced anatomical review.

The die wear up to 80,800 hits on a prog-die setup for bare DP1180 steel was investigated in real production condition. In total, 31 die inserts with the combination of 11 die materials and 9 coatings were evaluated. The analytical results of die service life for each insert were provided by examining the evolution of surface wear on inserts and formed parts. The moments of appearance of die defects, propagation of die defects, and catastrophic failure were determined. Moreover, the surface roughness of the formed parts for each die insert was characterized using Wyko NT110 machine. The objectives of the current study are to evaluate the die durability of various tooling materials and coatings for flange operations on bare DP 1180 steel and update OEM tooling standards based on the experimental results. The current study provides the guidance for the die material and coating selections in large volume production for next generation AHSSs.

Engine acoustics measured by microphones near the engine have been used in controlled laboratory settings for combustion feedback and even combustion phasing control, but the use of these techniques in a vehicle where many other noise sources exist is problematic. In this study, surface-mounted acoustic emissions sensors are embedded in the block of a 2.0L turbocharged GDI engine, and the signal is analyzed to identify useful feedback features. The use of acoustic emissions sensors, which have a very high frequency response and are commonly used for detecting material failures for health monitoring, including detecting gear pitting and ring scuffing on test stands, enables detection of acoustics both within the range of human hearing and in the ultrasonic spectrum. The high-speed acoustic time-domain data are synchronized with the crank-angle-domain combustion data to investigate the acoustic emissions response caused by various engine events.

This study concerns the generation of response surfaces for kinematics and injury prediction in pedestrian impact simulations using human body model. A 1000-case DOE (Design of Experiments) study with a Latin Hypercube sampling scheme is conducted using a finite element pedestrian human body model and a simplified parametric vehicle front-end model. The Kriging method is taken as the approach to construct global approximations to system behavior based on results calculated at various points in the design space. Using the response surface models, human lower limb kinematics and injuries, including impact posture, lateral bending angle, ligament elongation and bone fractures, can be quickly assessed when either the structural dimensions or the structural behavior of the vehicle front-end design change. This will aid in vehicle front-end design to enhance protection of pedestrian lower limbs.

This paper presents the implementation of an off-line optimized torque vectoring controller on an electric-drive vehicle with four in-wheel motors for driver assistance and handling performance enhancement. The controller takes vehicle longitudinal, lateral, and yaw acceleration signals as feedback using the concept of state-derivative feedback control. The objective of the controller is to optimally control the vehicle motion according to the driver commands. Reference signals are first calculated using a driver command interpreter to accurately interpret what the driver intends for the vehicle motion. The controller then adjusts the braking/throttle outputs based on discrepancy between the vehicle response and the interpreter command.

To investigate the effect of aeration on fluid-elastomer compatibility, 4 types of elastomers were aged in three gear lubes. The four types of elastomers include a production fluorinated rubber (FKM) and production hydrogenated nitrile rubber (HNBR) mixed by the part fabricator, a standard low temperature flexible fluorinated rubber (FKM, ES-4) and a standard ethylene-acrylic copolymer (AEM, ES-7) mixed by SAE J2643 approved rubber mixer. The three gear lubes are Fluid a, Fluid b and Fluid c, where Fluid b is a modified Fluid with additional friction modifier, and Fluid c is friction modified chemistry from a different additive supplier. The aeration effect tests were performed at 125°C for 504 hours. The aerated fluid aging test was performed by introducing air into fluid aging tubes as described in General Motors Company Materials Specification GMW16445, Appendix B, side-by-side with a standard ASTM D471 test.

Corrosion inhibitors (CIs) have been used for years to protect the supply and distribution hardware used for transportation of fuel from refineries and to buffer the potential organic acids present in an ethanol blended fuel to enhance storage stability. The impact of these inhibitors on spark-ignition engine fuel systems, specifically intake valve deposits, is known and presented in open literature. However, the relationship of the corrosion inhibitors to the powertrain intake valve deposit performance is not understood. This paper has two purposes: to present and discuss a second market place survey of corrosion inhibitors and how they vary in concentration in the final blended fuel, specifically E85 (Ethanol Fuel Blends); and, to show how the variation in the concentrations of the components of the CIs impacts the operation and performance of vehicles, specifically, the effects on intake valve deposit formation.

In recent years, there has been a growing interest in driver visibility. This is, in part, due to increasing emphasis placed on design factors influencing visibility such as: aerodynamics, styling, structural stiffness and vehicle packaging. During the development process of a vehicle, it is important to be able to quantify all of these factors. Visibility, however, owing to its sensory nature, has been harder to quantify. As a result, General Motors (GM) has undertaken a study to gain deeper insight into customer perceptions surrounding visibility. Clinics were conducted to help determine the relative importance of different metrics. The paper also explores several new metrics that can help predict customer satisfaction based on vehicle configuration.

A numerical and corresponding experimental study was undertaken to identify the ability to accurately predict combustion performance using our 3-D numerical tools for a direct-injection homogeneous-charge engine. To achieve a significant range of combustion rates, the evaluation was conducted for the engine operating with and without enhanced charge motion. Five charge motion configurations were examined, each having different levels of swirl and tumble flow leading to different turbulence generation and decay characteristics. A detailed CFD analysis provides insight into the in-cylinder flow requirements as well as the accuracy of the submodels. The in-cylinder air-fuel distribution, the mass-averaged swirl and tumble levels along with mean flow and turbulent kinetic energies are calculated throughout the induction and compression processes.

Determining Li-ion battery life through life modeling is an excellent tool in determining and estimating end-of-life performance. Achieving End-of-Life (EOL) can be challenging since it is difficult to achieve both cycle and calendar life during the same test without years of testing. The plan to correlate testing with the model included three (3) distinct temperature ranges, beginning with the four-Season temperature profile, an aggressive profile with temperatures in the 50 to 55°C range, and using a mid-temperature range (40-45°C) as a final comparison test. A high duty-cycle drive profile was used to cycle all of the batteries as quickly as possible to reach the one potential definition of EOL; significant increases in resistance or capacity fade.

This paper discusses subjective and objective approaches to quantifying ride performance in three sections: (1) Separates overall ride quality into five components-impact feel, shake, isolation, motion control, and smoothness; (2) Discusses approaches to objectively quantifying ride performance; (3) Provides analytical and test data to illustrate trade-offs in performance between the components of ride. The final section of this paper presents customer clinic data indicating customer preferences for the trade-off balance between ride performance attributes, specifically motion control versus smoothness.

The projected frontal area of a vehicle has a significant impact on aerodynamic drag, and thus is an important parameter, for vehicle development, benchmarking, and modeling. However, determining vehicle frontal area can be tedious, time consuming, expensive, or inaccurate. Existing methods include analysis of engineering drawings, vehicle projections, 3D scanners, planimeter measurements from photographs, and estimations using vehicle dimensions. Currently accepted approximation methods can be somewhat unreliable. This study focuses on introducing a method to find vehicle frontal area using digital images and subtraction functions via MATLABs' Image Processing Toolbox. In addition to an overview of the method, this paper describes several variables that were examined to optimize and improve the process such as camera position, surface glare, and vehicle shadow effects.

General Motors and the Takata Corporation have worked together to bring to production a new, industry first technology called the Front Center Airbag which is being implemented on General Motors' 2013 Midsize Crossover Vehicles. This paper reviews field data, describes the hardware, and presents occupant test data to demonstrate in-position performance in far side impacts. The Front Center Airbag is an airbag that mounts to the inboard side of the driver front seat. It has a tubular cushion structure, and it deploys between the front seating positions in far side impacts, near side impacts and rollovers, with the cushion positioning itself adjacent the driver occupant's head and torso. This paper includes pictures of the technology along with a basic description of the design. In-position occupant performance is also described and illustrated with several examples. Single occupant and two front occupant far side impact test data are included, both with and without the airbag present.

The fifth generation of General Motor's “Small Block” 90-degree V engine family has been developed with a totally new combustion system. This system employs direct fuel injection (DI) and carefully architected in-cylinder flow field development in order to significantly improve all aspects of combustion system performance. Efficiency improvements stem from increased compression ratio, greatly improved dilution tolerance, and excellent knock resistance. The asymmetric, 2-valve (2V) layout of the “Small Block” engine presented unique challenges in developing the combustion system, but also offered unusual opportunities for an elegant solution while retaining the traditional “Small Block” attributes of packaging efficiency and power density.

ASIL decomposition is a method described in the ISO 26262 standard for the assignment of ASILs to redundant requirements. Although ASIL decomposition appears to have similar intent to the hardware fault tolerance concept of IEC 61508-2, ASIL decomposition is not intended to reduce ASIL assignments to hardware elements for random hardware failures, but instead focuses on functions and requirements in the context of systematic failures. Based on our participation in the development of the standard, the method has been applied in different ways in practice, not all of which are fully consistent with the intent of the standard. Two potential reasons that may result in the use of “modified” ASIL algebra include the need of OEMs to partition a system and specify subsystem requirements to suppliers and the need for designers to construct systems bottom up.

Cost and robustness are key factors in the design of diesel engines for low power density applications. Although compression ignition engines can produce very high power density output with turbocharging, naturally aspirated (NA) engines have advantages in terms of reduced cost and avoidance of system complexity. This work explores the use of direct injection (DI) and exhaust gas recirculation (EGR) in NA engines using experimental data from a single-cylinder research diesel engine. The engine was operated with a fixed atmospheric intake manifold pressure over a map of speed, air-to-fuel ratio, EGR, fuel injection pressure and injection timing. Conventional gaseous engine-out emissions were measured along with high speed cylinder pressure data to show the load limits and resulting emissions of the NA-DI engine studied. Well known reductions in NOX with increasing levels of EGR were confirmed with a corresponding loss in peak power output.

Recently, high-speed optical imaging data for a single operating point of a spray-guided gasoline engine has, along with the flamelet model and the G-equation theory, enabled the development of the new spark-ignition model SparkCIMM. Within its framework, detailed chemistry flamelet models capture the experimental feature of multiple localized ignition events along the excessively stretched and restriking spark channel, as well as the observations of non-spherical highly corrugated early turbulent flame fronts. The developed flamelet models account for the substantial turbulent fluctuations in equivalence ratio and enthalpy present under spray-guided conditions. A non-unity Lewis number formulation captures the deficient species diffusion into the highly curved flame reaction zone.