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Uncertainty in Calculations Using Lambourn's Critical Speed Procedure
Technical Paper
2013-01-0779
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Critical Speed Formula (CSF) belongs to the canon of tools used in reconstruction of vehicle accidents. It is used to calculate vehicle speed at the beginning of tire yaw marks and, together with the entire methodology of processing the information contained in the marks into the data, is often referred to as the Critical Speed Method (CSM). Its great practical importance as well as recurring doubts as to the reliability make it one of the best experimentally and theoretically studied methods. Although the CSF applies in fact to a point mass, it is used with reference to a vehicle, i.e., an increasingly complicated multi-body system. Accident reconstruction experts point out the particular usefulness of Lambourn's research concerning the CSM in respect to a passenger car. Because his method by virtue of solid research basis is extensively applied in practice, the paper is focused specifically on Lambourn's methodology in terms of analysis of uncertainty and influence of vehicle properties. Regarding the first problem, sensitivity and uncertainty due to the parameters of the CSM was analyzed. Regarding the latter one, simulation tests using programs of different degrees of complexity were performed, taking into account criteria which were not considered in experimental tests. It has also been shown that in the case of unknown braking deceleration and large curvature of yaw mark, it will be desirable to shorten the chord c during the measurement and adjust the m/c (where m denotes the middle coordinate) ratio to the range from 0.01 to 0.03. This will ensure the reduction of calculation uncertainty to a level not exceeding ± 10%, regardless of the torques applied to the wheels. The article presents the theoretical arguments supporting and extending Lambourn's thesis concerning error no greater than ± 10%, subject to the guidelines prescribed by Lambourn.
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Wach, W., "Uncertainty in Calculations Using Lambourn's Critical Speed Procedure," SAE Technical Paper 2013-01-0779, 2013, https://doi.org/10.4271/2013-01-0779.Data Sets - Support Documents
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References
- Bartlett , W. , Wright , W. , Masory , O. , Brach , R. et al. Evaluating the Uncertainty in Various Measurement Tasks Common to Accident Reconstruction SAE Technical Paper 2002-01-0546 2002 10.4271/2002-01-0546
- Guzek , M. “Analiza prostoliniowego hamowania samochodu jako procesu stochastycznego”, (“Analysis of Straight Line Braking as a Stochastic Process”) Zeszyty Naukowe Politechniki Świętokrzyskiej, Mechanika 71 147 156
- Muttart , J. Development and Evaluation of Driver Response Time Predictors Based upon Meta Analysis SAE Technical Paper 2003-01-0885 2003 10.4271/2003-01-0885
- Lozia , Z. and Guzek , M. Uncertainty Study of Road Accident Reconstruction - Computational Methods SAE Technical Paper 2005-01-1195 2005 10.4271/2005-01-1195
- Brach , R. Vehicle Accident Analysis and Reconstruction Methods Society of Automotive Engineers, Inc. Warrendale, PA 978-0-7680-0776-3 2005
- Bohan , T., L. and Damask A. C. Forensic Accident Investigation: Motor Vehicles Semon , M. Determination of Speed from Yaw Marks Bohan and Dmask Michie Betterworth Charlottesville 1995
- Sledge , N. and Marshek , K. Formulas for Estimating Vehicle Critical Speed From Yaw Marks - A Review SAE Technical Paper 971147 1997 10.4271/971147
- Sledge , N. and Marshek , K. Vehicle Critical Speed Formula - Values for the Coefficient of Friction - A Review SAE Technical Paper 971148 1997 10.4271/971148
- Cannon , J. A Study of Errors in Yaw-Based Speed Estimates Due to Effective Braking SAE Technical Paper 2003-01-0888 2003 10.4271/2003-01-0888
- Cliff , W. , Lawrence , J. , Heinrichs , B. , and Fricker , T. Yaw Testing of an Instrumented Vehicle with and without Braking SAE Technical Paper 2004-01-1187 2004 10.4271/2004-01-1187
- Fischer , W. Challenging the Critical Speed Formula In Light Of the Daubert Decision SAE Technical Paper 2005-01-3141 2005 10.4271/2005-01-3141
- Amirault , G. and MacInnis , S. Variability of Yaw Calculations from Field Testing SAE Technical Paper 2009-01-0103 2009 10.4271/2009-01-0103
- Beauchamp , G. , Hessel , D. , Rose , N. , Fenton , S. et al. Determining Vehicle Steering and Braking from Yaw Mark Striations SAE Int. J. Passeng. Cars - Mech. Syst. 2 1 291 307 2009 10.4271/2009-01-0092
- Lambourn , R., F. The Calculation of Motor Car Speeds from Curved Tyre Marks Journal of the forensic Science Society 1986 29 371 386
- Brach , R. An Analytical Assessment of the Critical Speed Formula SAE Technical Paper 970957 1997 10.4271/970957
- Lambourn , R. Braking and Cornering Effects with and without Anti-Lock Brakes SAE Technical Paper 940723 1994 10.4271/940723
- Lambourn , R., F. , Jennings , P. and Knight , I. Critical Speed Yaw Mark Calculations with and without Electronic Stability Control Proceedings of the 1st joint ITAI-EVU Conference ITAI + EVU Publishers Hinckley 2009 209 235
- Struski J. Wach W. Dyskretny model pojazdu o dużej wydajności numerycznej, (A Vehicle Discrete Model of High Numerical Efficiency) Czasopismo Techniczne. Mechanika 2004 545 554
- Wach , W. and Struski , J. Rear Wheels Multi-Link Suspension Synthesis with the Application of a “Virtual Mechanism” SAE Technical Paper 2006-01-1376 2006 10.4271/2006-01-1376
- Hirschberg , W. , Rill , G. and Weinfurter , H. User-Appropriate Tyre-Modelling for Vehicle Dynamics in Standard and Limit Situations Vehicle System Dynamics 2002 38 2 103 125
- Kluziewicz , M. and Maniowski , M. “Stany nadsterowności podsterownego samochodu z przednim napędem”, (“Transient Oversteering of an Understeering Car with Front Wheel Drive”) Zeszyty Naukowe Instytutu Pojazdów Politechniki Warszawskiej 1 77 2012 Wydawnictwo Politechniki Warszawskiej Warszawa 2010 169 177
- BN-90/3615-/06, Projekt normy Pojazdy samochodowe. Badania kierowalności i stateczności. Zmiana pasa ruchu i wejście w zakręt samochodów osobowych (Project of standard: “Motor Vehicle. Stability and Steerability. Lane Change Maneuver and Going a Car into a Bend”)