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Technical Paper

Biomechanically Articulated Chair Concept and Prototypes

1997-02-24
970591
The human torso includes three major segments, the thoracic (rib cage) segment, lumbar segment, and pelvic segment to which the thighs are attached. The JOHN model was developed to represent the positions and movements of these torso segments along with the head, arms, and legs. Using the JOHN model, a new seat concept has been developed to support and move with the torso segments and thighs. This paper describes the background of the biomechanically articulated chair (BAC) and the development of BAC prototypes. These BAC prototypes have been designed to move with and support the thighs, pelvis, and rib cage through a wide variety of recline angles and spinal curvatures. These motions have been evaluated with computer modeling and with initial experience of human subjects. Results from computer modeling and human subjects show that the BAC will allow a broad range of torso postures.
Technical Paper

Development of Dynamic Simulation Models of Seated Reaching Motions While Driving

1997-02-24
970589
A research effort was initiated to establish an empirical data base and to develop predictive models of normal human in-vehicle seated reaching motions while driving. A driving simulator was built, in which a variety of targets were positioned at typical locations a driver would possibly reach. Reaching motions towards these targets were performed by demographically representative subjects and measured by a state-of-the-art motion analysis system. This paper describes the experiment conducted to collect the movement data, and the new techniques that are being developed to process, analyze, and model the data. Some initial findings regarding the role of torso assistive motion, the effect of speed used in completing a motion on multi-segment dynamic postures, and illustrative results from kinematic modeling are presented.
Technical Paper

Development of Human Back Contours for Automobile Seat Design

1997-02-24
970590
Driver and passenger comfort, as related to automotive seats, is a growing issue in the automotive industry. As this trend continues, automotive seat designers and developers are generating a greater need for more anthropometrically accurate tools to aid them in their work. One tool being developed is the JOHN software program that utilizes three-dimensional solid objects to represent humans in seated postures. Contours have been developed to represent the outside skin surfaces of three different body types in a variety of postures in the sagittal plane. These body types include: the small female, the average male, and the large male.
Technical Paper

Roll Over Detection

1997-02-24
970606
Some aspects on the detection of critical roll over situations for car safety applications will be presented. The detection via acceleration sensitive devices will be discussed as well as the detection via roll rate sensing elements. A combination of both sensors, the inclination sensing element and the roll rate sensing element seems to be the most feasible way for realization of a safe roll over detection.
Technical Paper

Development of a Magnetoelastic Torque Transducer for Automotive Transmission Applications

1997-02-24
970605
The development of a transducer for sensing the torque on the output shaft of a four speed rear wheel drive automatic transmission is described. Magnetoelastic polarized ring technology was selected based on its independence from shaft properties and its non-contact mode of sensing. The ring and several intermediate sleeves were attached by press fits onto an experimental shaft. The magnetic field arising from the ring with the application of torque was sensed by flux gate sensing elements. Ability to accurately measure the output torque of an engine driven transmission over its full range of torque and speed was demonstrated by dynamometer tests.
Technical Paper

Signal Detection Methods for Magnetostrictive Sensors

1997-02-24
970604
Magnetostrictive sensors offer many attractive features. Their strain sensitivity is significantly higher than that of strain gages. They are simple, rugged and inexpensive. Signal conditioning requirements for the magnetostrictive sensors are determined by the selection of a signal detection method. This article experimentally investigates different signal detection methods for single branch magnetostrictive sensors with conventional excitation and detection coils. Monitoring excitation voltage while holding excitation current constant, or monitoring excitation current while holding excitation voltage constant produces much better output signal compared to the detection voltage. Furthermore, this study suggest that the detection coil is not really needed, leading to a novel single branch magnetostrictive sensor without a detection coil.
Technical Paper

Giant Magnetoresistance Materials and Integrated Magnetic Sensors

1997-02-24
970603
Large changes in resistance with magnetic field exhibited by recently discovered thin-film multilayer structures offer new opportunities in the sensors field. Compatibility of these Giant Magnetoresistive (GMR) materials with conventional semiconductor processing technology and semiconductor underlayers allows the production of inexpensive, ultra-small, smart sensors with enhanced magnetic sensitivity. The action of GMR materials is described along with their application to sensor configurations for detecting magnetic fields, magnetic field gradients, and magnetic fields from currents. Characteristics of these sensors are discussed and compared to conventional magnetic field sensors. Finally, the exciting combination of GMR materials with semiconductor underlayers in smart sensors with linear or digital (switched) outputs is explored.
Technical Paper

Applications of Magnetoresistive Sensors in Navigation Systems

1997-02-24
970602
Most navigation systems today use some type of compass to determine heading direction. Using the earth's magnetic field, electronic compasses based on magnetoresistive (MR) sensors can electrically resolve better than 0.1 degree rotation. Discussion of a simple 8-point compass will be described using MR sensors. Methods for building a one degree compass using MR sensors will also be discussed. Compensation techniques are shown to correct for compass tilt angles and nearby ferrous material disturbances.
Technical Paper

High Accuracy Semiconductive Magnetoresistive Rotational Position Sensor

1997-02-24
970601
Recently there is demand for rotation sensors capable of high-accuracy detection and very low-speed detection of rotation at high temperature for automobile use. To meet this requirement, a rotation sensor using an InSb thin-film magneto-resistors with good thermal stability has been developed. This sensor transduces magnetic flux change due to gear rotation to resistance change. It is composed of InSb thin-film magneto-resistors fabricated by a newly developed process and signal shaping circuits where resistor signals are converted to digital signals using no amplifier. Accordingly, the signals are independent of the measured frequencies, making possible very low speed (0 to 20 Hz) detection. The sensor stably operates in the temperature range from -40 to 150 degree C for thousands hours. There is no need for a shielded harness due to the digital output signal.
Technical Paper

An Integrated Giant Magnetoresistive Rotational Speed Sensor

1997-02-24
970600
The presentation and paper will include a basic description of the Giant Magnetoresistive Ratio (GMR) effect, and will describe the magnetic, electronic and thermal performance of GMR materials. A functional automotive grade magnetic rotational wheel speed sensor using GMR materials as a sensing element has been fabricated. Performance data and some design considerations will be discussed. GMR materials have been integrated with standard silicon semiconductor processing allowing sensor and signal processing circuitry to be combined on a single chip. This single chip solution allows for a high performance small sized device. The ABS sensor is a zero speed, two wire device with an output current that switches between two levels, producing a square wave that has a frequency equal to the frequency of the target wheel teeth or magnetic poles. The device has a 50% +/- 10 duty cycle over the operating temperature and frequency ranges.
Technical Paper

Limitations in Predicting Human Vibration Response Characteristics From Manikins and Rigid Body Masses

1997-02-24
970598
The objective of this study was to use the driving-point impedance and transmissibility techniques to evaluate and compare the resonance behavior of two male humans, the Hybrid III aerospace manikin, and a rigid body mass using a rigid seat and a selected helicopter seat cushion. All occupants represented the 95th percentile or higher of the male population for weight. The results showed that the resonance frequencies associated with the peak impedance, chest, and head transmissibilities were significantly higher in the manikin regardless of the seating configuration or input acceleration level. While the magnitude of the peak impedance was higher in the manikin, differences in the chest and head transmissibilities depended on both the seating configuration and acceleration level. Neither the manikin nor the rigid body were effective in predicting the primary human resonance effects occurring in the sensitive region of 4 to 8 Hz.
Technical Paper

Testing Options Available for Head Impact Protection Development

1997-02-24
970576
Occupant protection in the event of interior head impact is a major issue in the development process of interior component countermeasures. As phase-in schedules for head impact protection regulations fast approach, auto safety engineers are presented with major challenges in regard to developing suitable design alternatives. This paper presents a variety of testing options which are available to evaluate interior design options. These test alternatives vary from simple component-level drop tests to in-vehicle compliance testing. Each type of test serves a specific purpose in the development of interior components from a head impact protection perspective. The basic parameters for each type of test, including mass, form shape, velocity, and motion will be discussed. Test data from component-level testing is presented, as well as the advantages and disadvantages for each alternative.
Technical Paper

Experimental Devices to Simulate Toepan and Floorpan Intrusion

1997-02-24
970574
Two sled systems capable of producing structural intrusion in the footwell region of an automobile have been developed. The first, System A, provides translational toepan intrusion using actuator pistons to drive the footwell structure of the test buck. These actuator pistons are coupled to the hydraulic decelerator of the test sled and are powered by hydraulic energy from the impact event. Resulting footwell intrusion is characterized using a toepan pulse analogous to the acceleration pulse used to characterize sled and vehicle decelerations. Sled tests with System A indicate that it is capable of accurately and repeatably simulating toepan/floorpan intrusion into the occupant footwell. Test results, including a comparison of lower extremity response between intrusion sled tests and no intrusion sled tests, indicate that this system is capable of repeatable, controlled structural intrusion during a sled test impact.
Technical Paper

A Procedure for Quantifying the Effective Leak Area of a Full Size Airbag

1997-02-24
970577
In this paper, we present an experimental and analytic procedure for determining the effective leak and vent areas of a full size airbag. Three different bag materials were tested and analyzed: 420 D (72 X 46), 420 D (49 X 49), and 840 D (32 X 32). An airbag model in CAL3D was used to inversely compute the effective leak area based on experimental data. Regression analysis was then performed to find the best fit of mathematical models for estimating effective leak areas as a function of pressure. Following a similar procedure, the effective vent area was also analyzed. Data are presented for a passenger bag and a driver bag. These results are useful for occupant dynamics simulations.
Technical Paper

Measurement Techniques for Angular Velocity and Acceleration in an impact Environment

1997-02-24
970575
The University of Virginia is investigating the use of a magnetohydrodynamic (MHD) angular rate sensor to measure head angular acceleration in impact testing. Output from the sensor, which measures angular velocity, must be differentiated to produce angular acceleration. As a precursor to their use in actual testing, a torsional pendulum was developed to analyze an MHD sensor's effectiveness in operating under impact conditions. Differentiated and digitally filtered sensor data provided a good match with the vibratory response of the pendulum for various magnitudes of angular acceleration. Subsequent head drop tests verified that MHD sensors are suitable for measuring head angular acceleration in impact testing.
Technical Paper

Apparatus and Method for Side Impact Testing

1997-02-24
970572
The introduction of the dynamic FMVSS 214 crash test requirement has prompted the need for an economical test method for the development of side impact occupant protection devices. Full scale side impact crash testing is too costly for the development testing of occupant protection components. This paper describes a unique test method for side impact sled testing which utilizes a standard 12-inch HYGE type sled facility. It has been demonstrated, with several hundred tests, to provide high repeatability and good correlation with full vehicle side impact crash tests. An overview of the device and details on how it is used is provided. Typical data correlation between sled tests and crash tests is shown for FMVSS 214(dynamic) testing. EEVC side impact and lateral crash tests into a rigid pole have also been correlated with this device and will be made available upon request.
Technical Paper

Intrusion Factors and Their Effects on Steering Column Movements During Vehicle's Frontal Impact Testing

1997-02-24
970573
Significant dashpanel intrusion is seen in some cars after severe frontal crashes at high speeds or after offset impact with rigid barrier or both. This intrusion may also result in severe steering column displacements and rotation. Knowledge of both responses is critical for designing an efficient vehicle front end that will respond well in crash. The intrusion has an effect on deciding the car front end length, while the column movements have an effect on the driver dummy's response. For reasons of developing efficiency and safety in vehicles and due to lack of published research, studies were conducted to understand the nature of the intrusion phenomenon as well as the mechanics of the steering column movement in the presence of intrusion. This paper describes an experimental investigation on intrusion and steering column movements.
Technical Paper

Wiper System Dynamic Behavior

1997-02-24
970588
In this paper are presented some results about the dynamic of the wiper systems, vibratory phenomena and some influences of the friction, the weight and the clearances.
Technical Paper

The Effects of Variability in Vehicle Structure and Occupant Position on Side Impact Dummy Response Using the MIRA M-SIS Side Impact Technique

1997-02-24
970571
Side impact crashworthiness presents a complex problem due to the dynamic interaction between the occupant and the intruding vehicle side structure. As there is a direct impact between the occupant, and the door and B-post trim, small variations in the vehicle structural behaviour can have a significant effect on the dummy response and injury levels. Significant variability in dummy response between crash tests causes problems when evaluating the vehicle side structure and development of side impact restraint systems. A programme of research tests has been conducted at the Motor Industry Research Association (MIRA) using the MIRA - Side Impact System (M-SIS) technique to evaluate the dynamic response of side impact dummies in actual side impact environments. With the implementation of the European side impact legislation in 1998 the effects of variations in dummy location and velocity profile need to be understood.
Technical Paper

Rolling Bearing Analysis Codes “BRAIN” - The Estimation of Rolling Bearing Performance for an Automotive Application

1997-02-24
970586
A computer program package named “BRAIN” has been developed to simulate the kinematics and the performance of rolling bearings under various running conditions. The calculation time necessary for running BRAIN software on a PC is very short. Various outputs can be obtained using BRAIN such as running torque, roller skew angle, roller slippage, and PV values. Several experiments have been conducted to confirm the validity of BRAIN. The running torque of a four point contact ball bearing and that of a tapered roller bearing were measured. In addition, the skew of the roller in a needle bearing was measured. These experimental results were compared with the calculation results. The experiments and the calculations showed good agreement.
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