Terms:
SAE International Journal of Transportation Safety
AND
5
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Markov Chain-based Reliability Analysis for Automotive Fail-Operational Systems

SAE International Journal of Connected and Automated Vehicles

,

SAE International Journal of Transportation Safety

AUDI AG-Andre Kohn, Rolf Schneider
Infineon Technologies AG-Antonio Vilela, Udo Dannebaum
  • Journal Article
  • 2017-01-0052
Published 2017-03-28 by SAE International in United States
A main challenge when developing next generation architectures for automated driving ECUs is to guarantee reliable functionality. Today’s fail safe systems will not be able to handle electronic failures due to the missing “mechanical” fallback or the intervening driver. This means, fail operational based on redundancy is an essential part for improving the functional safety, especially in safety-related braking and steering systems. The 2-out-of-2 Diagnostic Fail Safe (2oo2DFS) system is a promising approach to realize redundancy with manageable costs. In this contribution, we evaluate the reliability of this concept for a symmetric and an asymmetric Electronic Power Steering (EPS) ECU. For this, we use a Markov chain model as a typical method for analyzing the reliability and Mean Time To Failure (MTTF) in majority redundancy approaches. As a basis, the failure rates of the used components and the microcontroller are considered. The comparison to a non-redundant system shows a significantly higher reliability and MTTF of the redundant approaches.
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Reduction of Steering Effort in the Event of EPAS Failure using Differential Braking Assisted Steering

SAE International Journal of Transportation Safety

University of Michigan-Duanxiang Zhang, Bo Lin, Ahmet Kirli, Chinedum Okwudire
  • Journal Article
  • 2017-01-1489
Published 2017-03-28 by SAE International in United States
Electric Power Assisted Steering (EPAS) is widely adopted in modern vehicles to reduce steering effort. It is probable that some EPAS systems will experience a shutdown due to reliability issues stemming from electrical and/or electronic components. In the event of EPAS failure, power assist becomes unavailable and the steering system reverts to a fully manual state, leading to excessive steering torque demands from the driver to maneuver the vehicle at lower speeds, i.e., under 30 mph. This situation has resulted in dozens of reported crashes and several OEM safety recalls in the past few years. Inspired by recent work which utilizes independent driving torque of in-wheel-motor vehicles to reduce steering torque, this paper proposes the use of Differential Braking Assisted Steering (DBAS) to alleviate steep increases in steering torque upon EPAS failure. DBAS requires software upgrades with minimal hardware modification to EPAS, which is preferable for a backup system. A preliminary evaluation of DBAS is carried out using simulations in CarSim. Results show that DBAS reduces steering torque to similar levels as EPAS in all…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Fire Suppression Modeling & Simulation Framework for Ground Vehicles

SAE International Journal of Transportation Safety

Alion Science & Technology-Steven Hodges
US Army TARDEC-Vamshi Korivi, Steven McCormick
  • Journal Article
  • 2017-01-1351
Published 2017-03-28 by SAE International in United States
The US Army Tank Automotive Research, Development and Engineering Center (TARDEC) has developed a unique physics based modeling & simulation (M&S) capability using Computational Fluid Dynamics (CFD) techniques to optimize automatic fire extinguishing system (AFES) designs and complement vehicle testing for both occupied and unoccupied spaces of military ground vehicles.The modeling techniques developed are based on reduced global kinetics for computational efficiency and are applicable to fire suppressants that are being used in Army vehicles namely, bromotrifluoromethane (Halon 1301), heptafluoropropane (HFC-227ea, trade name FM200), sodium-bicarbonate (SBC) powder, water + potassium acetate mixture, and pentafluoroethane (HFC-125, trade name, FE-25). These CFD simulations are performed using High Performance Computers (HPC) that enable the Army to assess AFES designs in a virtual world at far less cost than physical-fire tests.This methodology is applied to vehicle crew compartments for multiple scenarios using HFC227e + SBC powder which is the suppressant combination used in most US combat and tactical vehicles with crew fire protection systems. Predicted and test results match qualitatively very well for overall suppression time as well as…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A New Data-Driven Design Method for Thin-Walled Vehicular Structures Under Crash Loading

SAE International Journal of Transportation Safety

Embry Riddle Aeronautical University-Xianping Du, Feng Zhu
Wayne State University-Clifford C. Chou
  • Journal Article
  • 2017-01-1463
Published 2017-03-28 by SAE International in United States
A new design methodology based on data mining theory has been proposed and used in the vehicle crashworthiness design. The method allows exploring the big dataset of crash simulations to discover the underlying complicated relationships between response and design variables, and derive design rules based on the structural response to make decisions towards the component design. An S-shaped beam is used as an example to demonstrate the performance of this method. A large amount of simulations are conducted and the results form a big dataset. The dataset is then mined to build a decision tree. Based on the decision tree, the interrelationship among the geometric design variables are revealed, and then the design rules are derived to produce the design cases with good energy absorbing capacity. The accuracy of this method is verified by comparing the data mining model prediction and simulation data. The result indicates that the data mining based methodology could overcome the weakness of traditional design method, i.e. lack of capability in information discovery from big datasets.
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Modeling of Rivets Using a Cohesive Approach for Crash Simulation of Vehicles in RADIOSS

SAE International Journal of Transportation Safety

Altair Engeneering GmbH-Marian Bulla
Ford Motor Company-Niels Pasligh, Robert Schilling
  • Journal Article
  • 2017-01-1472
Published 2017-03-28 by SAE International in United States
Rivets, especially self-piercing rivets (SPR), are a primary joining technology used in aluminum bodied vehicles. SPR are mechanical joining elements used to connect sheets to create a body in white (BiW) structure. To ensure the structural performance of a vehicle in crash load cases it is necessary to describe physical occurring failure modes under overloading conditions in simulations. One failure mode which needs to be predicted precisely by a crash simulation is joint separation. Within crash simulations a detailed analysis of a SPR joint would require a very high computational effort. The conflict between a detailed SPR joint and a macroscopic vehicle model needs to be solved by developing an approach that can handle an accurate macroscopic prediction of SPR behavior with a defined strength level with less computational effort. One approach is using a cohesive material model for a SPR connection. The paper describes cohesive element characteristics and calibration effort. Investigated element characteristics are an updated momentum calculation resulting from shear loads. It allows the adjustment of the width-height ratio for a constant meshing…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Bridging the Gap between Open Loop Tests and Statistical Validation for Highly Automated Driving

SAE International Journal of Transportation Safety

BMW AG-Alexander Koenig, Michael Gutbrod
KIT Karlsruhe Institute of Technology-Sören Hohmann, Julian Ludwig
  • Journal Article
  • 2017-01-1403
Published 2017-03-28 by SAE International in United States
Highly automated driving (HAD) is under rapid development and will be available for customers within the next years. However the evidence that HAD is at least as safe as human driving has still not been produced. The challenge is to drive hundreds of millions of test kilometers without incidents to show that statistically HAD is significantly safer. One approach is to let a HAD function run in parallel with human drivers in customer cars to utilize a fraction of the billions of kilometers driven every year. To guarantee safety, the function under test (FUT) has access to sensors but its output is not executed, which results in an open loop problem. To overcome this shortcoming, the proposed method consists of four steps to close the loop for the FUT. First, sensor data from real driving scenarios is fused in a world model and enhanced by incorporating future time steps into original measurements. Second, recorded time-shifted data is used to identify intentions of each driver of the surrounding traffic. Third, the real scene is used as…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

External Biofidelity Evaluation of Pedestrian Leg-Form Impactors

SAE International Journal of Transportation Safety

Hyundai Kia R&D-Haeyoung Jeon
University of Virginia-Daniel Perez-Rapela, Jason Forman, Jeff Crandall
  • Journal Article
  • 2017-01-1450
Published 2017-03-28 by SAE International in United States
Current state-of-the-art vehicles implement pedestrian protection features that rely on pedestrian detection sensors and algorithms to trigger when impacting a pedestrian. During the development phase, the vehicle must “learn” to discriminate pedestrians from the rest of potential impacting objects. Part of the training data used in this process is often obtained in physical tests utilizing legform impactors whose external biofidelity is still to be evaluated. This study uses THUMS as a reference to assess the external biofidelity of the most commonly used impactors (Flex-PLI, PDI-1 and PDI-2). This biofidelity assessment was performed by finite element simulation measuring the bumper beam forces exerted by each surrogate on a sedan and a SUV. The bumper beam was divided in 50 mm sections to capture the force distribution in both vehicles. This study, unlike most of the pedestrian-related literature, examines different impact locations and velocities. The results show how the Flex-PLI and the PDI-1 exert greater forces on the bumper beam than the THUMS, while the PDI-2 produced bumper beam forces similar to the THUMS. The PDI-2 is…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Comprehensive Validation Method with Surface-Surface Comparison for Vehicle Safety Applications

SAE International Journal of Transportation Safety

Chongqing University-Junqi Yang, Zhenfei Zhan, Ling Zheng, Gang Guo
Tongji University-Changsheng Wang
  • Journal Article
  • 2017-01-0221
Published 2017-03-28 by SAE International in United States
Computer Aided Engineering (CAE) models have proven themselves to be efficient surrogates of real-world systems in automotive industries and academia. To successfully integrate the CAE models into analysis process, model validation is necessarily required to assess the models’ predictive capabilities regarding their intended usage. In the context of model validation, quantitative comparison which considers specific measurements in real-world systems and corresponding simulations serves as a principal step in the assessment process. For applications such as side impact analysis, surface deformation is frequently regarded as a critical factor to be measured for the validation of CAE models. However, recent approaches for such application are commonly based on graphical comparison, while researches on the quantitative metric for surface-surface comparison are rarely found. To deal with this problem, a validation metric, which combines the discrepancies measurements in magnitude and shape, is proposed to evaluate the inconsistence between two deformed surfaces. For magnitude error, an exploited 2-Dimensional Dynamic Time Warping (2D-DTW) method is applied to address the mismatch in surface features between two surfaces. Geometric features, say mean curvatures…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

NHTSA’s Proposed Frontal Oblique Impact Test Protocol: Analyses and Evaluation

SAE International Journal of Transportation Safety

Ford Motor Company-Saeed Barbat, Xiaowei Li
  • Journal Article
  • 2017-01-1475
Published 2017-03-28 by SAE International in United States
On December 2015, The National Highway Traffic Safety Administration (NHTSA) published its proposal to implement U.S New Car Assessment Program (NCAP) changes covering three categories of crashworthiness, crash avoidance and pedestrian protection, beginning with the 2019 model year. The crashworthiness category included a new frontal oblique impact (OI) test protocol. The test compromises of a new Oblique Moving Deformable Barrier (OMDB), new THOR 50th percentile male (THOR-50M) anthropomorphic test device (ATD), and a new test configuration. An OMDB of 2,486 kg (5,480 lb) impacts a stationary target vehicle at a speed of 90 kph (56 mph) at an angle of 15 degrees with a 35% barrier overlap with the front end of the target vehicle. In vehicle-to-vehicle collisions, the lighter weight vehicle experience higher velocity change and higher acceleration levels, thereby, occupants in the lighter vehicle experience higher injury risk. This paper describes the analyses of a series of 31 OI tests conducted by NHTSA, in which the target vehicles used were of different sizes and weight distribution ranging between 1034 Kg (SMART)-2624 Kg (Silverado).Deformation…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

ERRATUM: Study of Reproducibility of Pedal Tracking and Detection Response Task to Assess Driver Distraction

SAE International Journal of Transportation Safety

Honda R&D Co., Ltd.-Tatsuya Iwasa, Toshihiro Hashimoto
  • Journal Article
  • 2015-01-1388.01
Published 2015-04-14 by SAE International in United States
1. On page 111, the authors have described a method to assess driver distraction. In this method, participants maintained a white square size on a forward display by using a game gas pedal of like in car-following situation. The size of the white square is determined by calculating the distance to a virtual lead vehicle. The formulas to correct are used to explain variation of acceleration of the virtual lead vehicle. The authors inadvertently incorporated old formulas they had used previously. In the experiments discussed in the article, the corrected formulas were used. Therefore, there is no change in the results. The following from the article:
Annotation ability available