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Sound Analysis Method for Warble Noise in Electric Actuators

General Motors-Nathan T. Parker
Published 2019-06-05 by SAE International in United States
Multiple automotive applications exist for small electric motors that are activated by vehicle occupants for various functions such as window lifts and seat adjusters. For such a motor to be described as high quality, not only should the sound it produces be low in amplitude, but it also needs to be free from pulsations and variations that might occur during its (otherwise) steady-state operation. If a motor’s sound contains pulsations or variations between 2 and 8 cycles per second, the variation is described as warble. To establish performance targets for warble noise at both the vehicle and component level a way to measure and quantify the warble noise must be established. Building on existing sound quality metrics such as loudness and pitch variation, a method is established by which processed sound data is put through a secondary operation of Fourier analysis. Thus warble can be reduced to a single value, and in this way, noise engineers have a basis to measure and report warble, and to facilitate product development with A/B comparisons. Depending on its…
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Target Setting Process for Hybrid Electric Drives Using TPA, Jury Study, and Torque Management

FCA US LLC-Vinod Singh, Anil Charan
InDepth Engineering Solutions-Aniket Parbat
Published 2019-06-05 by SAE International in United States
The idea of improved efficiency without compromising the “fun to drive” aspect has renewed the auto industry’s interest toward electrification and hybridization. Electric drives gain from having multiple gear ratios which can use advantageous operating set points thus increasing range. Furthermore, they benefit significantly from frequent decelerations and stopping as is experienced in city driving conditions. To recuperate as much energy as possible, deceleration is done at high torque. This presents an interesting but serious sound quality issue in the form of highly tonal whine harmonics of rapidly changing gears that do not track with vehicle speed thus being objectionable to the vehicle occupants. This paper presents an NVH target setting process for a hybrid electric transmission being integrated into two existing vehicles, one belonging to the premium segment and another aimed at enthusiasts with off-road applications. The demand for power has shifted from mechanical domain into electrical domain, and as such, the solution to electric drive NVH issues also lay partly, in the way these drive systems are calibrated. A time-domain Transfer Path Analysis…
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Ride Index Structure and Development Methodology

Vehicle Dynamics Standards Committee
  • Ground Vehicle Standard
  • J2834_201904
  • Current
Published 2019-04-24 by SAE International in United States
This recommended practice defines methods for the measurement of periodic, random and transient whole-body vibration. It indicates the principal factors that combine to determine the degree to which a vibration exposure will cause discomfort. Informative appendices indicate the current state of knowledge and provide guidance on the possible effects of motion and vibration on discomfort. The frequency range considered is 0.5 Hz to 80 Hz. This recommended practice also defines the principles of preferred methods of mounting transducers for determining human exposure. This recommended practice is applicable to light passenger vehicles (e.g., passenger cars and light trucks). This recommended practice is applicable to motions transmitted to the human body as a whole through the buttocks, back and feet of a seated occupant, as well as through the hands of a driver. This recommended practice offers a method for developing a ride performance index but does not specifically describe how to apply this index to assessment or comparison of specific vehicles.
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Thoracic Spine Extension Injuries in Occupants with Pre-Existing Conditions during Rear-End Collisions

Exponent, Inc.-Mathieu Davis, Jessica Isaacs, Martin Graber, Jacob Fisher
Published 2019-04-02 by SAE International in United States
Certain ankylosing spondyloarthropathies such as ankylosing spondylitis (AS) or diffuse idiopathic skeletal hyperostosis (DISH) can substantially alter clinicopathologic spine biomechanics as well as injury mechanisms in rear-end motor vehicle collisions. AS is an inflammatory disease which can lead to structural impairments of the spine secondary to flowing ossification along the spinal column, including ossification across the spinal discs, facet joints, and ligaments, and it has also been associated with diffuse osteoporosis of the spine. DISH is characterized by excess bone formation along the spinal column, encompassing the annulus and forming the thickest and strongest bridging osteophytes over adjacent vertebral bodies at the level of the disc space. In both conditions the spine is mechanically stiffened and generally more kyphotic than a healthy spine. This paper presents a series of case studies in which a front-seat occupant with ankylosing spondyloarthropathy experienced a moderate- or high-speed rear-end collision and sustained a thoracic spine fracture/dislocation, often with spinal cord injuries. Forward acceleration of the occupant by the seat back in each case resulted in straightening of the kyphotic…
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Development of Subject-Specific Elderly Female Finite Element Models for Vehicle Safety

Chongqing University-Yunlei Yin, Junming Li, Qingmiao Wang
State Key Lab of Veh NVH & Safety Technology/Chongqing Univ-Wenxiang Dong, Zhenfei Zhan
Published 2019-04-02 by SAE International in United States
Previous study suggested that female, thin, obese, and older occupants had a higher risk of death and serious injury in motor vehicle crashes. Human body finite element models were a valuable tool in the study of injury biomechanics. The mesh deformation method based on radial basis function(RBF) was an attractive alternative for morphing baseline model to target models. Generally, when a complex model contained many elements and nodes, it was impossible to use all surface nodes as landmarks in RBF interpolation process, due to its prohibitive computational cost. To improve the efficiency, the current technique was to averagely select a set of nodes as landmarks from all surface nodes. In fact, the location and the number of selected landmarks had an important effect on the accuracy of mesh deformation. Hence, how to select important nodes as landmarks was a significant issue. In the paper, an efficient peak point-selection RBF mesh deformation method was used to select landmarks. The multiple peak points were selected to expand landmarks set, so as to improve the morphing quality compared…
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Evaluation of Occupant Kinematics in Low- to Moderate-Speed Frontal and Rear-End Motor Vehicle Collisions

Exponent Inc.-Alexander Bruno, Megan Toney-Bolger, Juff George, Jeffrey Koller, Anton Filatov, Joseph Olberding
Published 2019-04-02 by SAE International in United States
Low- to moderate-speed motor vehicle collisions are a common crash type and are sometimes associated with injury complaints. Understanding occupant motion (kinematics) in response to low- and moderate-speed motor vehicle collisions is important for evaluating occupant interactions with interior vehicle structures, including the restraint systems, with the ultimate goal of assessing injury potential. Furthermore, quantitative occupant kinematic data from full-scale crash testing of late-model passenger vehicles is limited for collisions at low- to moderate-speeds. The current study reports kinematic data from full-scale frontal and rear-end crash tests of late-model, mid-size sedans with delta-Vs ranging from 6.0 to 19.0 kph (3.7 to 11.8 mph) and 5.6 to 19.5 kph (3.5 to 12.1 mph), respectively. For each test vehicle, the motion of a Hybrid III 50th-percentile male anthropomorphic test device (ATD) restrained in the driver seat was recorded using high-speed onboard video. Motion tracking of the video was used to evaluate the excursion and velocity of each ATD’s head, shoulder, elbow, and knee with respect to the vehicle interior. Restraint loads were recorded via load cells placed…
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Detection of Presence and Posture of Vehicle Occupants Using a Capacitance Sensing Mat

Clemson University-Rahul Prasanna Kumar, Yunyi Jia
Ford Motor Company-David Melcher, Pietro Buttolo
Published 2019-04-02 by SAE International in United States
Capacitance sensing is the technology that detects the presence of nearby objects by measuring the change in capacitance. A change in capacitance is triggered either by a change in dielectric constant, area of overlap or distance of separation between the electrodes of the capacitor. It is a technology that finds wide use in applications such as touch screens, proximity sensing etc. Drawing motivation from such applications, this paper investigates how capacitive sensing can be employed to detect the presence and posture of occupants inside vehicles. Compared to existing solutions, the proposed approach is low-cost, easy to deploy and highly efficient. The sensing system consists of a capacitance-sensing mat that is embedded with copper foils and an associated sensing circuitry. Inside the mat the foils are arranged in rows and columns to form several touch-nodes across the surface of the mat. The system segregates row and column capacitances from each other and computes their tensor product to generate grayscale capacitance-sensing images. The images are real-time pictorial representation of the capacitance of each touch-node. When the mat…
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Influence of Partial Recirculation on the Build-Up of Cabin Carbon Dioxide Concentrations

CalsonicKansei North America Inc.-Gursaran D. Mathur
Published 2019-04-02 by SAE International in United States
Carbon dioxide exhaled by occupants remains within the cabin during operation of HVAC unit in recirculation mode. The CO2 inhaled by the occupants goes into their blood stream that negatively affects occupant’s health. ASHRAE Standard 62 specifies safe levels of carbon dioxide in conditioned space for humans. The CO2 concentration limit per ASHRAE is 700 ppm over ambient conditions on a continuous basis. In a recent investigation the author had developed a model to predict cabin carbon dioxide concentrations for recirculation mode as a function of time, number of occupants, vehicle speed, body leakage characteristics, occupant lung capacities and concentrations of the carbon dioxide coming out from occupant’s mouth, blower position and vehicle age. This developed model has been modified to simulate cabin airflows from 100% recirculation mode to 100% outside air mode, i.e., for any percentage of partial recirculation.In this paper, the author has presented simulated results for a vehicle from D segment (mid-sized sedan). The effect of partial recirculation is investigated to maintain good air quality per ASHRAE standard 62. Detailed analysis has…
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Has Electronic Stability Control Reduced Rollover Crashes?

Toyota Motor Corp.-Rini Sherony
Virginia Tech-Luke Riexinger, Hampton Gabler
Published 2019-04-02 by SAE International in United States
Vehicle rollovers are one of the more severe crash modes in the US - accounting for 32% of all passenger vehicle occupant fatalities annually. One design enhancement to help prevent rollovers is Electronic Stability Control (ESC) which can reduce loss of control and thus has great promise to enhance vehicle safety. The objectives of this research were (1) to estimate the effectiveness of ESC in reducing the number of rollover crashes and (2) to identify cases in which ESC did not prevent the rollover to potentially advance additional ESC development.All passenger vehicles and light trucks and vans that experienced a rollover from 2006 to 2015 in the National Automotive Sampling System Crashworthiness Database System (NASS/CDS) were analyzed. Each rollover was assigned a crash scenario based on the crash type, pre-crash maneuver, and pre-crash events. The Insurance Institute for Highway Safety ESC availability database was matched to each NASS/CDS case vehicle by the vehicle make, model, and model year. ESC effectiveness was computed using the quasi-induced exposure method.From 2006-2015, control loss was a factor in 29.7%…
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The Kinematic Analysis of Occupant Excursions and Accelerations during Staged Low Speed Far-Side Lateral Vehicle-to-Vehicle Impacts

Engineering Systems Inc.-Peggy Shibata, Julius Roberts, James Sprague, Alyson Light, Jacob Stegemann, Manuel Meza-Arroyo, Shawn Capser
Published 2019-04-02 by SAE International in United States
The collection of research regarding occupant kinematics during low speed lateral vehicle-to-vehicle impacts is far less comprehensive than the much larger body of literature that quantifies the occupant kinematics associated with low speed rear end (longitudinal) impacts. In order to augment the available data, a series of 39 low speed far-side lateral vehicle-to-vehicle impacts were conducted in a laboratory setting. A combination of accelerometers and 3D motion tracking was used to characterize the motions of both the Target and Bullet vehicles during their collisions. The Target vehicle was initially stationary; the Bullet vehicle impacted the Target vehicle at the front passenger side door. The Bullet vehicle pre-impact speeds across all tests ranged from approximately 2.5 to 5.5 mph (4.0 to 8.9 kph; 1.1 to 2.5 m/s).Eight volunteers participated in the study. Volunteers were seated in the driver seat during the impacts and were outfitted with accelerometers on their head and wore reflective markers for 3D motion tracking on the left side of their body. The experimental design included conducting lateral impacts while the volunteers were…
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