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Technical Paper

2003 Chevrolet Kodiak and GMC TopKick Airbag Sensing System Development

Airbag systems have been part of passenger car and truck programs since the mid-1980's. However, systems designed for medium and heavy duty truck applications are relatively new. The release of airbag systems for medium duty truck has provided some unique challenges, especially for the airbag sensing systems. Because of the many commercial applications within the medium duty market, the diversity of the sensing environments must be considered when designing and calibrating the airbag sensing system. The 2003 Chevrolet Kodiak and GMC TopKick airbag sensing development included significant work, not only on the development of airbag deployment events but also non-deployment events – events which do not require the airbag to deploy. This paper describes the process used to develop the airbag sensing system deployment events and non-deployment event used in the airbag sensing system calibration.
Technical Paper

3-D Video Sensor for Dynamic Out-of-Position Sensing, Occupant Classification and Additional Sensor Functions

A 3-D video sensor designed for in-vehicle operation is presented in this paper. This sensor enables improved occupant protection according to the Federal Motor Vehicle Safety Standard (FMVSS) 208 and beyond. Interior sensors integrated in current occupant protection systems are especially designed for Occupant Classification (OC). However, these interior sensors do not measure the distance between the head and the air bag module. As a result, the air bags deploy independently from the occupants' Out-Of-Position (OOP) status in crash situations. On the contrary, the sensor presented in this paper overcomes this shortcoming by providing dynamic Out-Of-Position Sensing (OOPS) capabilities in addition to occupant classification. The requirements of dynamic OOPS are discussed and an appropriate test device and test procedure are described. Furthermore, the paper presents the sensor principle, the hardware architecture and algorithms for image data processing.
Technical Paper

5th Percentile Driver Out of Position Computer Simulation

A finite element model of a folded airbag with the module cover and steering wheel system was developed to estimate the injury numbers of a 5th percentile female dummy in an out-of-position (OOP) situation. The airbag model was correlated with static airbag deployments and standard force plate tests. The 5th percentile finite element dummy model developed by First Technology Safety Systems (FTSS) was used in the simulation. The following two OOP tests were simulated with the airbag model including a validated steering wheel finite element model: 1. Chest on air bag module for maximum chest interaction from pressure loading (MS6-D) and 2. Neck on air bag module for maximum neck interaction from membrane loading (MS8-D). These two simulations were then compared to the test results. Satisfactory correlation was found in both the cases.
Technical Paper


A mathematical simulation of the operation of a compressed-gas airbag system is developed. A system was built and tested, and the analysis is evaluated on the basis of these tests. Included in the study are nonideal gas effects, manifold and diffuser effects, bag stretch, bag leakage, and overpressurization of the passenger compartment. Interaction between a single rigid object and the bag is also considered. A correlation between bag pressure and the force it generates is obtained. This allows the development of an analytic model for determining the motion of a single rigid mass interacting with a dynamically inflating airbag mounted in a moving vehicle. An application of the model to study rebound of the occupant from the airbag is presented.
Technical Paper

A Baseband Radar System for Auto Braking Application

This paper describes a BAseband Radar (BAR) sensor for radar braking application; an early version of the BAR concept was reported previously as a precollision sensor for air bag activation. In this paper we show how the normally wide effective beamwidth of the BAR is narrowed by using interferometry in conjunction with a novel delay line digital processor scheme. The beamwidth of the breadboard system spans a traffic lane width at 45 meters. The paper describes the details of the BAR sensor front-end and preliminary test results sponsored by the U.S. Department of Transportation and the Institute for Telecommunication Sciences.
Technical Paper

A CAE Methodology to Simulate Testing a Rearward Facing Infant Seat during FMVSS 208 Low Risk Deployment

The Federal Motor Vehicle Safety Standard or FMVSS 208 requires passenger cars, multi-purpose vehicles, trucks with less than unloaded vehicle weight of 2,495 kg either to have an automatic suppression feature or to pass the injury criteria specified under low risk deployment test requirement for a 1 year old dummy in rearward and forward facing restraints as well as a forward facing 3 and 6 year old dummy. A convertible child seat was installed in a sub-system test buck representing a passenger car environment with a one-year- old dummy in it at the passenger side seat and a passenger side airbag was deployed toward the convertible child seat. A MADYMO model was built to represent the test scenario and the model was correlated and validated to the results from the experiment.
Technical Paper

A Case Study of High Strain Rate Effects in Glass Filled Thermoplastic Materials

Choosing the correct thermoplastic for an instrument panel application requires a thorough understanding of the environmental and performance conditions. In the case of a high speed event, such as an airbag deployment or a knee bolster intrusion, standard static tensile properties may not adequately define the material performance. The engineer needs to understand the materials sensitivity to high strain rate extremes. The subject of this paper is the enhancement of part performance through the testing and knowledge of material performance over a range of strain rates.
Technical Paper

A Case Study of a Hidden Airbag Door Deployment, with an SMA IP, Using FEA and Data Acquisition for Design Optimization

The automotive industry has seen an increase in the application of passenger side hidden airbag door technology. The hidden airbag door presents several challenges to the design and analysis Engineer. Airbag deployments function as a system of components, acting in concert. Design optimization requires investigating the individual parts and their interactions as a structure. This paper is a case study using Finite Element Analysis and Data Acquisition as a guide, to provide design optimization and predict deployment performance.
Technical Paper

A Case Study: Improvements in Automotive Motion Simulators Using Six Sigma Methodologies

Newer automobiles have complex dynamic and stability controls due to regulations, competition, and safety concerns. More systems require testing at the subcomponent level to ensure proper operation in the final vehicle assembly. Many of the stability and navigation features originally designed for aircraft components are now being incorporated into automobiles. Certain types of motion test simulators were originally designed for testing aircraft sensors as: gyroscopes, inertial navigation systems (INS), inertial measurement units (IMU), and attitude heading and reference systems (AHARS) This same type of equipment is now used for automotive testing as: airbag fuse sensors, anti-skid sensors, rollover sensors, vehicle stabilization systems, active suspension sensors, and navigation systems.
Technical Paper

A Compact Sled System for Linear Impact, Pole Impact, and Side Impact Testing

Accelerator-type sled systems have been very useful to the automotive industry for many years. These systems have allowed engineers to effectively evaluate a safety component in a frontal crash environment without having to conduct a full-scale crash test. While accelerator-type sleds are an excellent tool for frontal crashworthiness development, the energy required to simulate a side impact or lateral pole impact test is just a small fraction of the total capacity of the system. In light of this, a project was undertaken to develop a system which incorporated many features of the current accelerator-type sled system, but was designed to simulate non-frontal crash test cases. This paper describes the development and test applications for the new sled system. The operating theory and general design is similar to current accelerator-type sled systems, although the new system has been scaled down significantly.
Technical Paper

A Comparison of the Safety Performance of Aluminum and Steel in Conventional Automotive Construction

It is often said that heavier cars are inherently safer than lighter ones. However, when all cars are built with steel, larger size necessarily implies greater weight, so it is unclear whether the improved safety correlates to the weight or size of the vehicle. Using a publicly available computer model of the Ford Taurus, it was thought that this perception could be tested. The existing steel model, with the addition of a Hybrid III dummy and driver side airbag, was validated against actual crash test data. The structure was converted to aluminum, structural stiffness was calculated, and the steel and aluminum crash simulation results were compared. The aluminum model, utilizing monocoque sheet structure, weld bonded joining, and tailor welded blanks, weighed 200 kg less than the steel model and performed as well.
Technical Paper

A Complete Frontal Crash Sensor System - 1

This is the first paper in a new series to present a coherent theory of sensing frontal crashes, define the characteristics of future airbag sensor systems and to present examples of how this theory can be implemented. After summarizing the relevant conclusions from the authors' previous papers, this paper concludes that future systems should contain: crush zone sensors which sense relevant impacts to all portions of the vehicle front; an occupant position sensor as an input to the sensing system; and a mechanical safing/arming sensor having a long dwell. It is further concluded that cars should be designed so that only impacts involving the front of the vehicle need be sensed for the deployment of frontal protection airbags. This series of papers has the main goal of determining an overall theory of frontal crash sensing and the resulting desirable properties of sensor systems. A second goal is to give examples of how this theory can be realized in real sensor systems.
Technical Paper

A Computer Simulation for Motorcycle Rider–Motion in Collision

A computer simulation method for motorcycle rider motion in a collision on a passenger car has been developed. The computer simulation results were in two cases of collision, at 45 degree and 90 degree angles against the side of a passenger car. The simulated results were compared to the test results for validation. The simulation software of explicit finite element method (FEM) has been used, because of its capability for expressing accurate shape and deformation. The mesh size was determined with consideration for simulation accuracy and calculation time, and an FEM model of a motorcycle, an airbag, a dummy, a helmet and a passenger car were built. To shorten the calculation time, a part of the model was regarded as a rigid body and eliminated from the contact areas. As a result, highly accurate dummy posture and head velocity at the time of contact on the ground were simulated in the two cases of collision.
Technical Paper

A Consumer Case for the Air Bag and the Problem of Public Acceptance

Impositions placed on vehicle occupants by safety belts and safety belt use are substantial and will increase as systems to encourage or force belt usage are incorporated. By comparison, the known impositions of air bags are minor, but to these must be added other requirements, the extent of which are not yet well-known. Substantial fleet testing of air bags will clarify most of these inconveniences. Automobile manufacturers and the National Highway Traffic Safety Administration have failed to generate public support for the air bag. Lack of consumer support will continue unless greater resources are allocated to equip fleet vehicles with air bag systems so that a reliable record of air-bag efficacy can be compiled.
Technical Paper

A Consumer Viewpoint on Car Restraint Systems

Lap-shoulder belts became standard with very little, very inneffective explanation of why they should be used. National effort is needed to persuade all to use them, and auto industry to improve them, and see the effect of buzzers and interlocks before mandating airbags or equivalent. This paper looks at the past history of restraints, forecasts the future if airbags are to be mandated without explaining them. AAA of Michigan motorist survey shows strong dislike of airbags, a preference for seatbelt-shoulder harness if choice must be made, a strong feeling that it is not the business of government to mandate airbag or seatbelt use. Question is raised about claims of number of lives that airbags will save. Are they too high?
Technical Paper

A Correlation Methodology of Airbag Body Block Test and Simulation Using Optimization Technique

The integrated correlation methodology is applied to the correlation of the airbag body block test and the component tests of sub systems consisting of the steering control system. By using the optimization technique for the occupant simulation model involving two-dimensional curves as the input, the optimal scale factors of the input F-D curves are found in order to minimize the sum of deviations between simulation and test results. In addition, the optimal one-dimensional unknown inputs that can't be obtained by component tests are found. It is found that the optimization technique used in this study is very suitable for the correlation of the occupant simulation model that has 2-dimensional test input data, and it is able to shorten the entire correlation time and ensure the reliability of the correlation result. This correlation methodology can be applied to the sled test and the barrier test for validating the occupant analysis model.
Technical Paper

A Critique of Single Point Sensing

In two previous SAE papers (1,2) by the authors, supporting analysis was presented showing the difficulty in achieving a timely response to real-crash events using a single point sensor mounted in the non-crush zone of the vehicle (tunnel, cowl, etc.). The analysis demonstrated the propensity to deploy the air bag(s) late during certain of these events. If a vehicle occupant was not wearing a safety belt, the deceleration forces of the crash could place the occupant out of position and resting against the air bag when it was deployed. In another SAE paper (3) by H. J. Mertz et al, the authors demonstrated that animals, used as surrogates for humans, could be injured if positioned against an air bag at the time of deployment. Arguments are presented here to show that there is insufficient information in the crash pulse as sensed in the non-crush zone to deploy an air bag in time for the unbelted occupant.
Technical Paper

A Development of Active Vent Airbag for the Passenger New NCAP

For the robust passenger NCAP(New Car Assessment Program) 5star and the stable neck injury performance, a new concept of passenger airbag has been required. Especially, the deployment stability and the vent hole control technology of the passenger airbag can be improved. According to these requirements, the deployment stability technique has been studied and the ‘Active Vent’ technology has been developed. As a result, these technologies have led to achieve the robust NCAP rating and are applied to the production vehicles.
Technical Paper

A Diffusive Gas Jet Model in PAM-SAFE for Airbag Inflation

Among the forces acting on an occupant during the deployment of an airbag, the impact force due to gas jets coming out of the inflator may be important. Consequently, the semi-analytical theory of high-velocity gas jets including velocity spreading due to turbulent diffusion has been incorporated into the explicit finite element computer program PAM-SAFE for occupant safety. The jet model, described in this paper, takes into account the geometry and thermodynamics of the inflator, the transfer of jet momentum to the moving airbag and the distribution of momentum due to diffusion. Since the intersection of every jet with the airbag is computed each timestep, the algorithm is consistent with numerical airbag unfolding. Experimental validation of the jet model has been performed at Automotive Systems Laboratory Inc. by firing actual inflators on rigid flat plates at several distances.
Technical Paper

A Discussion of the Air Bag System and Review of Induced Injuries

The air bag system is described in terms of four basic elements: the crash sensors and controls, the inflator, the air bag itself, and the diagnostic circuitry. A general discussion of these elements is provided and a review of air bag related injuries is also presented which includes data from various sources such as the University of Michigan Transportation Research Institute, National Highway Traffic and Safety Administration, Transport Canada, and the Insurance Institute for Highway Safety. The most frequently occurring accident type is the frontal collision and has been the main focus of safety efforts with regard to restraint systems. Air bags are an effective injur/prevention device, however their deployment can introduce new injury mechanisms. Air bags save lives and decrease the severity of major injuries in exchange for increasing the number of minor injuries.