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Technical Paper

Accuracy and Sensitivity of Yaw Speed Analysis to Available Data

2019-04-02
2019-01-0417
Accident reconstructionists rarely have complete data with which to determine vehicle speed, and so the true value must be bracketed within a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of sport utility vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history.
Journal Article

Reconstructing Vehicle Dynamics from On-Board Event Data

2019-04-02
2019-01-0632
These predictions were generated by directly integrating the VCH data and by using the VCH data as inputs to PC-Crash simulations. The predicted positions and headings were then compared to the actual position and heading data measured using differential GPS synchronized to the VCH data record.
Technical Paper

An Analytical Review and Extension of Two Decades of Research Related to PC-Crash Simulation Software

2018-04-03
2018-01-0523
PC-Crash is a vehicular accident simulation software that is widely used by the accident reconstruction community. ...The goal of this article is to review the prior literature that has addressed the capabilities of PC-Crash and its accuracy and reliability for various applications (planar collisions, rollovers, and human motion). ...In addition, this article aims to add additional analysis of the capabilities of PC-Crash for simulating planar collisions and rollovers. Simulation analysis of five planar collisions originally reported and analyzed by Bailey [2000] are reexamined.
Technical Paper

Electronics and Algorithms for Rollover Sensing

2004-03-08
2004-01-0343
Rollover sensing and discrimination generally requires an algorithm that monitors vehicle motion and anticipates conditions that will lead to a rollover. In general, a deploy command is required in a time frame such that safety measures can be activated early enough to protect the occupants. A rollover discrimination system will typically include internal motion sensors, vehicle signals from other on-board sensors, and a microprocessor to execute the deployment algorithm. A supplemental signal path is used to arm the system, making it less susceptible to single point component failures. In this chapter we explore basic concepts of rollover sensors and system mechanization, rollover discrimination algorithms, and arming methodology. A simulation environment that models the performance of the system across part tolerance, temperature extremes and component age is used to estimate the scope of expected discrimination performance in the field.
Technical Paper

Essential Considerations in Delta-V Determination

2001-10-01
2001-01-3165
While Delta-V has been one of the most used indicators of accident severity for vehicle occupants, its actual determination remains a mystery to many who refer to it and use it. Delta-V is a term of art applied to a rapid change in vehicle velocity caused by impact forces during a collision. The Delta-V is associated with the high decelerations, which cause it and are applied to the occupants through restraint systems and collisions with the interior of the vehicle. This paper will serve as a primer for those new to the subject and a review for those who are familiar with the subject. Previous works by the authors will be referenced and other pertinent literature and data sources will be discussed. The analytical methods and test data used to calculate Delta-V will be presented and the relationship between Delta-V and other measures of impact severity, such as Barrier Equivalent Velocity and Energy Equivalent Speed will be discussed. The use of air bag sensor data will be included.
Technical Paper

PC-Crash and HVE, an Overview of Similarities and Differences

2001-03-05
2001-01-0505
HVE 1 and PC-Crash 2 have been the subject of numerous SAE papers. Both programs have been offered to reconstructionists for the purpose of analyzing vehicle accidents and presenting the resulting motions in 3D graphical form.
Technical Paper

An Evaluation of Rectified Bitmap 2D Photogrammetry with PC-Rect

1997-02-24
970952
Without good-quality measurements taken at the time of an accident the analyst is faced with the need to extract measurement data from incident scene photographs. This paper discusses the history and development of the mathematical model for two-dimensional (2D) single exposure analytical photogrammetry, presents the software PC-Rect, and compares the analytical results obtained with PC-Rect to survey results. The sensitivity of the analytical results to the variation in such parameters as subject distance, camera height, digital photograph resolution, and bitmap density is discussed. The concept of using the directly rectified scanned photograph in the reconstruction task is introduced, and the utility of performing the dynamic simulation directly on the rectified photograph is discussed.
Technical Paper

RICSAC-97 A Reevaluation of the Reference Set of Full Scale Crash Tests

1997-02-24
970961
Research performed in the 1970's revealed significant limitations in the available documentation of vehicle crush information and trajectory spinout information. As a result a series of full-scale crash tests were performed which became known as the Research Input for Computer Simulation of Automobile Collisions (RICSAC) crash tests. Previous research using the RICSAC test results, particularly in relation to the validation of accident reconstruction computer programs, has varied widely in acceptance, interpretation and presentation of the RICSAC test results. This paper presents a detailed review and decipherment in useable form of the original 12 crash tests that were performed within the RICSAC program. A new method of analyzing accelerometer data from arbitrary sensor positions, on the basis of discrete measures of the vehicle responses rather than complete time-histories, is defined.
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