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Technical Paper

In-vehicle Speech Intelligibility for the Hearing Impaired Using Speech Intelligibility Index

2011-05-17
2011-01-1681
Individuals with hearing impairments often report hearing difficulties within the driving environment. This is an ever growing issue given the increasing population of senior aged drivers. In this study, Speech Intelligibility Index (SII) is used to predict in-vehicle speech intelligibility of individuals having common hearing impairments. The effect of hearing threshold levels obtained from audiograms and the impact of vehicle background noise measured for various vehicle operating conditions, road surface types and talker and listener configurations are investigated. This is done by using measured and user-defined speech spectra as described by ANSI S3.5-1997 (Methods for Calculation of the Speech Intelligibility Index). The results demonstrate poor speech intelligibility for most situations considered and provide evidence for the need to improve automotive interior sound quality in terms of speech intelligibility for hearing impaired drivers including aged drivers.
Technical Paper

Analysis of Determining Parameters of Acoustical Comfort Inside Vehicles

2011-05-17
2011-01-1686
The description of subjectively perceived acoustical comfort inside vehicle compartments is a complex challenge. On the one hand, it depends on physically measurable events like acoustical stimuli with a defined sound pressure level and frequency distribution. On the other hand, it is also strongly dependent on further factors like the customer's individual expectations, the previously made experiences and other contextual influences. Furthermore, many different driving conditions have to be considered for a customer-related assessment of driving comfort. In this paper, the mechanisms of acoustical comfort inside vehicle compartments are described on basis of various measurements, listening tests and qualitative assessments. The acoustical properties of driving noises at various driving conditions were taken into account as well as room-acoustical parameters of vehicle interiors and factors of speech communication between passengers.
Technical Paper

An integrated framework of real and micro simulated driving cycles to evaluate a new emissions factors model

2011-08-30
2011-01-2063
Transport activities contribute significantly to air pollution. For this reason any policy or plan, carried out by administration or institution, requires the assessment of its impact on the emissions. To assess the overall pollutant production from transport, it is necessary to calculate emission factors. For this aim several methods exist which only use the average speed of the traffic stream, which can be theoretically obtained by vehicles flow and density on the road. Recently, a new statistical approach has been developed capable to consider more attributes than the simple mean speed to characterize driving behaviour, not only in the determination of driving cycles but also in the emission modelling. In this context, a meso scale emission model, named KEM, Kinematic Emission Model, able to calculate emission factor was developed. However, it is necessary to consider that the input to this model is, in any case, the driving cycle.
Technical Paper

Application of Human Factors and Cognitive Neuroscience Principles in the Design of Vehicle Information Displays

2011-09-13
2011-01-2256
The present paper provides a general review of trends in vehicle information display designs, specifically “dashboards,” noting that the purpose of those dashboard displays is to provide information that allows for safe and lawful operation of those vehicles. The author describes how these trends appear to have been driven by a combination of historical precedents including vehicle interior design, available vehicle display technology, and, later, by development of vehicle data busses. The paper describes human factors and cognitive neuroscience issues that affect an operator's ability to read gauges in a dashboard display. The paper reports the results of the author's 2008 research where 71 of 101 survey respondents indicated that they find it hard to read their recreational vehicle gauges. It describes participants' significantly positive responses to the author's dashboard display prototype developed using human factors and cognitive neuroscience principles.
Journal Article

Field Demonstration of Heavy Vehicle Camera/Video Imaging Systems

2011-09-13
2011-01-2245
To help drivers monitor the road and to reduce blind spots, Camera/Video Imaging Systems (C/VISs) display live video from cameras mounted on the truck's exterior to drivers using displays inside the truck cabin. This study investigated drivers' performance with C/VISs in a real-world trucking operation. Twelve commercial drivers' performance with and without a C/VIS was continuously recorded while they each drove for four months. Half of the drivers used a commercially available C/VIS that had a side-view camera on each fender. The other drivers used an advanced C/VIS (A-C/VIS) that had side-view cameras, a rear-view camera, and night-vision capabilities. This paper presents the study's final results and expands on the preliminary results that were previously reported. Detailed analyses of drivers' involvement in Safety-Critical Events (SCEs), their lane change performance, and their opinions of the C/VISs are presented.
Technical Paper

Development of a Multi-Body Systems Approach for Analysis of Launch Shudder in Rear Wheel Driven Vehicles

2009-05-19
2009-01-2073
Driveline shudder is a low-frequency (10 Hz - 30 Hz) vibration issue of vehicles that can occur under various test conditions. Specifically, launch shudder is an issue that can be prevalent under vehicle take-off conditions. Factors that typically contribute to launch shudder include stick-slip excitation of friction materials (clutches) and driveline excitations, in particular, on rear wheel drive (RWD) vehicles. Shudder caused by the driveline excitation is generally related to the universal joints (Cardan joints) in the driveline system. In this case, the u-joint forces and kinematics induce a 2nd order excitation when operated under a driveline angle. This document focuses on launch shudder phenomena resulting from driveline system excitation on a RWD vehicle. An initial treatment of the physics governing launch shudder and typical factors influencing the shudder levels in vehicle are provided.
Technical Paper

Method of NVH Quality Rating of Diesel Combustion Noise Using Typical Driving Modes

2009-05-19
2009-01-2078
The development of a new method to evaluate the NVH quality of diesel combustion noise bases upon following questions by regarding typical driving modes: Driving behavior with diesel vehicles Which driving situation causes an annoying diesel combustion noise Judgment of diesel combustion noise as good or bad A suitable test course was determined to regard typical driving situations as well as the European driving behavior. Vehicles of different segments were tested on that course. The recorded driving style and the simultaneously given comments on the diesel combustion noise results to a typical driving mode linked to acoustics sensation of diesel combustion noise. The next step was to simulate this driving mode on the chassis dynamometer for acoustical measurements. The recordings of several vehicles were evaluated in listening test to identify a metric. The base of metric was objective analyses evaluating diesel combustion noise in relevant driving situations.
Journal Article

A Study of HCCI Combustion using Spectroscopic Techniques and Chemical Kinetic Simulations

2009-11-03
2009-32-0070
This study was conducted to investigate the influence of low-temperature reactions on the Homogeneous Charge Compression Ignition (HCCI) combustion process. Specifically, an investigation was made of the effect of the residual gas condition on low-temperature reactions, autoignition and the subsequent state of combustion following ignition. Light emission and absorption spectroscopic measurements were made in the combustion chamber in order to investigate low-temperature reactions in detail. In addition, chemical kinetic simulations were performed to validate the experimental results and to analyze the elemental reaction process. The results made clear the formation behavior of the chemical species produced during low-temperature HCCI reactions.
Technical Paper

Design of the Occupant Protection System for Critical Side Impact requirements

2009-12-13
2009-28-0055
This paper describes the critical side impact requirements of overall global side regulations and the sensitivity of various side injury parameters on NCAP rating assessment. The federal side impact regulation FMVSS 214 made very stringent by adding oblique pole impact in addition to moving deformable barrier (MDB) test. Though the vehicle velocity is less in oblique pole test, the dynamic intrusions are more which causes severe injury for 5th and 50th %le occupants than MDB test. It was observed that typical injury parameter in side impact requirements is the thorax compression than other injuries, because it is very sensitive than Pelvic, Abdomen regions. To meet these critical injury requirements in side impact, the optimal side restraint system is mandatory in order to develop a safer vehicle with high NCAP score. The side restraint system includes side airbags (thorax and curtain), Hip pusher block/foam padding, door trim arm rest, seat belts and seats.
Technical Paper

An integrated approach to extract basic Suspension Data through Integration of tri-axial spindle coupled road simulator, wheel force transducer and a wheel vector sensor.

2009-12-13
2009-28-0027
In a highly competitive global as well as the domestic market of the passenger car industry, the search for the complete car is on the forefront. With such a situation, carmakers are experimenting with innovative technology on various development programs to cater the needs of the customer. This paper shows one such experimentation to extract the basic suspension Kinematics & Compliance data with the integration of a Tri-axial Spindle Coupled road load simulator, a wheel force transducer and a Wheel Vector Sensor in absence of expensive Suspension Parameters Measuring Machine (SPMM).
Technical Paper

Diesel Hybrids - The Logical Path towards Hybridisation

2009-12-13
2009-28-0046
Concerns on emissions and their effects on climate changes are currently the drivers behind automotive technology. Diesels have been faring better with CO2 and fuel economy norms. However the state of art diesel engines emerging from various OEMs and trend as far as marginal improvements in the emissions and fuel economy potentials indicate that diesels are at the limits. In this scenario, diesel hybrid electric powertrains have shown promise to push the limits even further and offer the ideal platform to maximize benefits of hybridization. This paper shows that the diesel hybrids are the logical way to bridge the gap between conventional vehicles and electric vehicles.
Technical Paper

Kinematic Analysis of Multi-Axle Steering System for Articulated Vehicle

2009-01-21
2009-26-0067
Steering of non-driven axles of semi-trailer results in improvement of maneuverability during negotiating sharp turn and reduces tyre drag and wear by relieving locked-in forces in comparison to non-steered axles. Among few, command steering mechanism is reported to be most efficient method of steering of articulated vehicles. In this type, the axles of semi-trailer are steered in relation with the articulation of tractor. The articulation angle of tractor is sensed by an actuation mechanism integrated on trailer at fifth wheel location and transferred hydraulically to the steering linkages. Mathematical equations have been developed based on Ackerman's Principle to estimate theoretical steering angle when Tractor-Trailer negotiate any turn. Steering linkage geometry has been conceptualised, kinematically modelled and analysed by using ADAMS. Equations developed for theoretical steering angles are incorporated in ADAMS as run time functions.
Technical Paper

Material Model Development of an Energy Absorbing Foam for Occupant Safety

2009-01-21
2009-26-0088
Different Original Equipment Manufacturers (OEMs) use different Finite Element (FE) codes to perform crash analyses. Primary explicit codes widely used are LS-DYNA, PAM-CRASH and RADIOSS. These codes help rapid evaluation of vehicle design in the preliminary phase, eliminating the need for cumbersome design changes post-physical validation trials. This is more so critical for crash and safety aspects of design. A variety of Energy Absorbing (EA) foams are offered to OEMs to meet the EA performance requirements. Also the FE codes offer a variety of standard material models to the analyst to choose from. The choice of material model is governed by factors such as type of foam under consideration, simplicity of modeling, available material test data, performance objectives, etc. The development of a validated material model is hence a complex task. This paper deals with development and validation of material models of IMPAXX for the FE codes RADIOSS and PAM-CRASH.
Technical Paper

Dashboard Stiffness Control for Reducing Knee Injury in Frontal Crashes

2009-01-21
2009-26-0006
In frontal crashes, one of the primary reasons for occupant injuries is hard contact with the vehicle interiors. While restraints like airbags, seat belt pre-tensioners etc. help in preventing direct contact of the upper body region; vehicle interiors play a critical role in controlling the lower body region injuries. Knee injuries can be controlled in various ways as follows: Avoiding contact with the dashboard by use of buckle pre-tensioners etc. Using restraints like knee airbags Optimizing the dashboard profile and stiffness at the contact locations All the above options have their own advantages and limitations. This paper explains the effect of dashboard stiffness tuning for controlling knee injuries in a frontal crash. The development methodology and some validation tools are discussed using a case study.
Technical Paper

Sensation and Measurement of Low and Very Low Frequency Time-Varying Sounds in Accordance with the Very Short Impulse Response of Low-Frequency Human Hearing

2011-05-17
2011-01-1665
Human hearing, with its active transducers, attention process and remarkable signal-processing abilities, challenges the transportation-product sound quality engineer to measure accordingly and has clearly given rise to the practice and tools of sound quality engineering. Transient events and/or level changes of various durations and magnitudes and over various frequency bandwidths are measurable with due care in the majority of “real-world” acoustic time-signal histories, and frequently carry subjective importance. Inspired by recent work with wind-turbine sound situations, the focus of this paper is to suggest reconsideration of some low-frequency measurement methodologies in the transportation realm.
Technical Paper

Ease of Conversation Development Method for Passenger Vehicles

2011-05-17
2011-01-1675
One measure of perceived quality in a new car is how easily the passengers can communicate. This includes communication between the passengers and also communication to the vehicle itself, as features such as Bluetooth and voice activated controls become increasingly common. Articulation Index (AI) has long been the standard in the automotive industry for evaluating the ease of communication. Previous studies have explained that AI, however, only evaluates the background noise that surrounds the listener; and does not capture changes in modulation of sound before reaching the listener. The telecommunication and construction industries have used Speech Transmission Index (STI) as a measure of communication. This method incorporates the masking effect of background noise, and modulation of the speech signal along the transmission path. This study focused to understand STI, cascade to component characteristics and modify characteristics to improve speech transmission inside vehicles.
Journal Article

How Body Pressure Distribution Can Map Soldier Comfort

2011-04-12
2011-01-0803
Currently, when the Army studies ride quality and comfort, 6 Watts of absorbed power is commonly cited as a target. However, absorbed power is dependent upon vehicle speed and road roughness and does not fully describe the direct interaction between the occupant and the seat cushion. Recently, there has been a great deal of growth in Body Pressure Distribution (BPD) measurement technologies. This growth in technology allows for new perspectives in quantifying ride comfort. Up to this point, the Army has not capitalized on these new technologies and still heavily on absorbed power to quantify ride comfort. This paper explores how the Army has benefited from pressure mapping technologies to complement absorbed power in quantifying ride comfort of military vehicles.
Technical Paper

Ejection Seat Cushions Static Evaluation for Three Different Installation Rail Angles

2011-04-12
2011-01-0806
Jet fighter missions have been known to last extended period of time. The need for a comfortable and safe seat has become paramount considering that fact that uncomfortable seats can lead to numerous health issues. Several health effects like numbness, pressure sore, low back pain, and vein thrombosis have been associated with protracted sitting. The cushion, and of late the installation rail angle are the only components of the ejection seat system that can be modified to reduce these adverse effects. A comprehensive static comfort evaluation study for ejection seats was conducted. It provides comparison between a variety of operational and prototype cushions (baseline cushion, honeycomb and air-cushion) and three different installation rail angles (14°, 18°, and 22°). Three operational cockpit environment mockups with adjustable installation rail angle were built. Ten volunteer subjects, six females and four males, ages 19 to 35, participated in the seat comfort evaluation.
Technical Paper

Analysis of Muscle Fatigue for Urban Bus Drivers using Electromyography

2011-04-12
2011-01-0801
Professional bus drivers are highly exposed to physical fatigue and work-related injuries because driving task includes complicated actions that require a variety of ability and cause extreme concentration or strain. For this reason, there has always been some sense of concern regarding driver fatigue, especially for drivers of commercial vehicles. In this study, we have tried to analyze quantitative fatigue degree of urban bus drivers by measuring their physiological signals. The investigation is made up of the following approaches: a traditional questionnaire survey and video-ethnographic method with 4-way cameras. The close-circuit cameras are installed to observe the upper and lower body of real drivers when they are in driving or even resting. This approach can help to understand urban bus drivers' behaviors and fatigue-related issues. Based on the video-ethnographic investigation results above, we have got certain patterns of drivers.
Journal Article

Effect of Obesity on Seated Posture Inside a Vehicle Based on Digital Human Models

2011-04-12
2011-01-0433
Seated posture inside a vehicle influences driver performance and control of a vehicle. Many vehicles do not properly allow for a natural seated posture for all drivers. Some vehicles are difficult to drive due to the fact that the driver is inadequately accommodated in the driver seat. For people of extreme stature, tall or short, and for people of extreme width, obese or pregnant populations, it can be difficult to safely operate a vehicle if there is not enough room in the cab or if some controls cannot be reached. This paper employs digital human models to study the effect of obesity on seated posture inside a vehicle. Eight digital human models, four non-obese and four obese, are subjected to reach tests inside a virtual vehicle cab. These tests are used to determine how obesity affects the clearance between the steering wheel and driver body and whether additional factors contribute to discomfort associated with obese people seated inside a vehicle.
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