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Technical Paper

Sensitivity of Accident Reconstruction Calculations

A number of simplistic formulae, based on particle dynamics, energy, and momentum methods are routinely employed by accident reconstructionists to calculate vehicle speeds immediately prior to impact. It is almost always the case that scene evidence and other information regarding important variables involved in such equations must either be estimated or can be measured only in an approximate way. ...Example problems illustrate the difficulties faced by accident reconstructionists as they grapple with incomplete and/or estimated values for important variables, and with the inherent sensitivity of some of the calculations to seemingly small variations in variable magnitudes.

Aircraft Accident Reconstruction and Litigation

This book provides a basic source of technical and legal information to participate intelligently in the search for probable causes and discussion of the legal aspects of aircraft accidents. It should be especially helpful to lawyers and engineers embarking on investigative careers. ...This book could be considered a postgraduate guide for the hardware-oriented aircraft accident investigator, especially the sections on human errors and human factors. This fourth edition includes chapters on the Freedom of Information Act, safety, discovery, spoliation of evidence, Death on the High Seas Act, tort litigation and more.
Journal Article

Automatic Transmission Gear Ratio Optimization and Monte Carlo Simulation of Fuel Consumption with Parasitic Loss Uncertainty

An enterprise approach for vehicle fleet balancing of fuel consumption objectives based upon selection of automatic transmission gearing strategy is presented. Monte Carlo simulations for the influence of parasitic loss uncertainty for the automatic transmissions selected from the generalized DOE were conducted to determine the range of fuel consumption that might be realized in production. ...Automatic transmission gearing parameter selection was unaffected by the variation introduced by the Monte Carlo simulations, but did show fuel consumption performance to vary upwards of 9 g CO2/km depending on applications and to have a direct impact on powertrain operating parameters.
Technical Paper

Particulate Matter Formation Dynamics as Investigated by Ultra-Accelerated Quantum Chemical Molecular Dynamics Coupled with Canonical Monte Carlo Method

Suppression or reduction of soot emissions is an important goal in the development of automotive engines for environmental and human health purposes. A better understanding at the molecular level of the formation process of soot particles resulting from collision and aggregation of smaller particles made of Polycyclic Aromatic Hydrocarbon (PAH) is needed. In addition to experiments, computational methods are efficient and valuable tools for this purpose. As a first step in our detailed computational chemistry study, we applied Ultra-Accelerated Molecular Dynamics (UAQCMD) and Canonical Monte-Carlo (CMC) methods to investigate the nucleation process. The UA-QCMD can calculate chemical reaction dynamics 107 times faster than conventional first principle molecular dynamics methods, while CMC can calculate equilibrium properties at various temperatures, pressures, and chemical compositions.
Technical Paper

Accident Investigation and Reconstruction Mapping with Aerial Photography

A system has been developed for investigating and reconstructing vehicular accidents using close-range aerial photography. Accident Investigation and Reconstruction Mapping with Aerial Photography, henceforth referred to as AIRMAP, utilizes a tethered blimp and suspended camera in a close-range aerial survey technique. ...Computer-generated graphics of physical evidence, such as vehicles, tire marks, and pedestrians, can be superimposed over the image to produce a plan view photographic map of the accident scene easily understood by a non-technical audience.
Journal Article

Evaluation of Sliding Mode Observers for Fault Reconstruction on the ADDSAFE Functional Engineering Simulator

The FDI schemes will ultimately be evaluated in the Industrial Benchmarking and Verification FES which uses Monte Carlo methods to generate a statistical distribution and covers all of the desired flight conditions, perturbations and uncertainties in the aircraft parameters under investigation. ...A robust sliding mode reconstruction scheme for the aircraft lateral axis, based on an LPV system representation is presented. ...The sliding mode LPV scheme utilizes LMIs to synthesize the gains of the observer to minimize the effect of uncertainty on the reconstruction signal. The equivalent output error injection signals are obtained from a second order sliding mode structure, which is less susceptible to noise compared to the typical signum function associated with first order sliding.

Basic Science and Art of Aircraft Wreckage Reconstruction

Basic Science and Art of Aircraft Wreckage Reconstruction is a unique title which addresses important aspects of investigating crashes, who does this kind of work, and how a healthy attitude and open mind are required to properly perform investigations. ...It also discusses what to expect from the on-scene part of the investigation, and the fundamental approaches to common types of wreckage reconstruction. Written by Don Knutson, a veteran of this industry, Basic Science and Art of Aircraft Wreckage Reconstruction is intended for the practitioner, student, or those who are simply curious about how aircraft wreckage is reconstructed. ...Written by Don Knutson, a veteran of this industry, Basic Science and Art of Aircraft Wreckage Reconstruction is intended for the practitioner, student, or those who are simply curious about how aircraft wreckage is reconstructed.
Journal Article

Accuracy of SUAS Photogrammetry for Use in Accident Scene Diagramming

Photogrammetry from images captured by terrestrial cameras and manned aircraft has been used for many years to model objects, create scale diagrams and measure distances for use in traffic accident investigation and reconstruction. Due to increasing capability and availability, Unmanned Aircraft Systems (UAS), including small UAS (SUAS), are becoming a valuable, cost effective tool for collecting aerial images for photogrammetric analysis. ...The results show the photogrammetric measurement of an accident scene from SUAS aerial imagery provides measurements with errors well below generally accepted ranges for accident reconstruction....The metric accuracy of scale accident scene diagrams created from SUAS imagery has yet to be compared to conventional measurement methods, such as total station and laser measurement systems, which are widely used by public safety officials and private consultants.
Technical Paper

Air Accident Investigation Programs - FDRV and AAIT

The Air Accident Investigation Tool (AAIT) allows simplified computer-reconstruction of air accidents. Both programs have been successfully applied to air accident/incident investigations.
Technical Paper

Evaluation of the Accuracy of Image Based Scanning as a Basis for Photogrammetric Reconstruction of Physical Evidence

Improvements in computer image processing and identification capability have led to programs that can rapidly perform calculations and model the three-dimensional spatial characteristics of objects simply from photographs or video frames. This process, known as structure-from-motion or image based scanning, is a photogrammetric technique that analyzes features of photographs or video frames from multiple angles to create dense surface models or point clouds. Concurrently, unmanned aircraft systems have gained widespread popularity due to their reliability, low-cost, and relative ease of use. These aircraft systems allow for the capture of video or still photographic footage of subjects from unique perspectives. This paper explores the efficacy of using a point cloud created from unmanned aerial vehicle video footage with traditional single-image photogrammetry methods to recreate physical evidence at a crash scene.
Technical Paper

Flight Path Reconstruction and Wind Estimation Using Flight Test Data from Crash Data Recorder (CDR)

This paper presents the implementation of flight path reconstruction (FPR) and wind estimation techniques applied to a high performance fighter aircraft. ...The estimation technique applied for data reconstruction is the extended Kalman filtering (EKF). The reconstructed trajectories can be compared with the actual flight trajectories such that, in case of unavailability of data from other sources (e.g., digital flight control computer), the algorithm should be able to reconstruct the trajectories with the minimum set of data available from the CDR. ...Wind estimation along with the trajectory reconstruction can give better accuracy in airspeed as well as flow angles. The algorithm also aims at determining the bias/systematic instrument errors and generating accurate aircraft state trajectories.
Technical Paper

An Optimization of Small Unmanned Aerial System (sUAS) Image Based Scanning Techniques for Mapping Accident Sites

Small unmanned aerial systems have gained prominence in their use as tools for mapping the 3-dimensional characteristics of accident sites. Typically, the process of mapping an accident site involves taking a series of overlapping, high resolution photographs of the site, and using photogrammetric software to create a point cloud or mesh of the site. ...These objects represent items commonly found at accident sites. The accident site was then documented with several different unmanned aerial vehicles at differing altitudes, with differing flight patterns, and with different flight control software. ...A mock accident site was created that included a stopped vehicle, a bicycle, and a ladder. These objects represent items commonly found at accident sites.
Technical Paper

Application of Signal Reconstruction to On-Road Emissions Testing

Data was taken from these analyzers and passed, off-line, through the reconstruction filter. In addition, part of the Federal Urban Driving Schedule was simulated on the chassis dynamometer and emissions data collected from the test vehicle.
Technical Paper

Failure Analysis in Support of Aircraft Accident Investigations

Subsequent to determination of component failure cause, corrective actions and development of field inspection methods are often imperative to preventing accident recurrence. Examples from several analyses of both military and commercial accident hardware are presented. ...High-speed ground impact, fire, secondary damage and the loss of components during an accident greatly hinder component failure analysis efforts and root cause determination. Careful evaluation of unfailed components can often give accident investigators the information needed to fill in gaps and determine the mishap sequence or cause. ...Careful evaluation of unfailed components can often give accident investigators the information needed to fill in gaps and determine the mishap sequence or cause.
Technical Paper

Signal Reconstruction Applied to a Fast Response Flame Ionisation Detector

The Fast-response Flame Ionisation Detector is used to measure levels of un-burnt hydrocarbons in the cylinder and exhaust of engines. Its fast response allows uHC emission processes to be resolved within an engine cycle. This paper describes a method for obtaining even greater detail by post-processing the output of the device using a Finite-Impulse Response (FIR) digital filter. The specification of the filter can be obtained by understanding the flow regimes within the sampling system. Examples from in-cylinder and exhaust sampling are presented with suggestions for implementation and further improvement.