What is the ATB?

'What Is' type questions related to highway safety, accident reconstruction and vehicle simulation
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What is the ATB?

Post by brian » Sat Oct 31, 2009 11:24 am

Q: What is the ATB?
A: ATB is the acronym for the Articulated Total Body (ATB).
  • The ATB Model is a public domain computer program that is used to simulate the dynamic motion of jointed systems of rigid bodies The ATB program is a research tool which is used primarily to interpolate and extrapolate the results of full-scale vehicle crash tests with anthropomorphic test dummies. A typical input file for the ATB program can require anywhere from 500 to 7000 parameters The inputs for ATB require detailed definitions of the occupant, the vehicle interior, the interaction of the occupant with the vehicle interior and definition of the acceleration environment. The appropriate values for input parameters are not readily available and there are no recognized “default” or “typical” values (ref 1].
  • In 1963 the U.S. Public Health Service and the Automobile Manufacturer’s Association, Inc. funded research at Calspan performed by Raymond R. McHenry to develop a mathematical model of an automobile occupant in a longitudinal collision. The resulting computer program was called the CAL-2D [2, 3, 4]. The research was aimed at the development of a response to a Consumer Reports issue [5] and related reports [6, 7] that included the assertion that American belts failed under the Swedish test conditions and "the major points of failure of the belts tested were the webbing…and the floor brackets themselves".
    The CAL-2D model was created "in order to help improve understanding of the complex relationships of force-acceleration-time-position-velocity that occur in the impact and energy-absorbing cycle of automobile passenger restraint systems". The study was performed to provide guidance concerning "(1) fundamental differences in the results obtained by static and dynamic testing and (2) the possible need for dynamic acceptance testing of seat belts. One of the results of the study was the conclusion that "the use of a very short stopping distance in a cart test of lap belts can produce a distorted comparison of the strength (when belt loads are not measured) and the performance of webbing materials with different load-elongation characteristics. A short (3") cart stopping distance, from 25 mph, produces increases in the magnitudes of both primary and secondary belt loading cycles over those obtained a more "realistic" (17") stopping distance, as encountered in automobile crashes". A subsequent follow-up contract for a 3 dimensional crash victim simulation at Calspan was directed by Dr. John Fleck and resulted in the creation of the Crash Victim Simulator (CVS) [9, 10]. In the 1980’s, the CVS was adapted for use by the Armstrong Aerospace Medical Research Laboratory Wright Patterson Air Force Base and was re-named the Articulated Total Body (ATB). The principal investigator of the CVS/ATB development at Calspan was Dr. John Fleck.[10]. The pioneering work by Dr. Fleck included extremely efficient integration routines for economical execution of the program and the addition of many extensions and refinements to move the mathematical model from 2 dimensions to 3 dimensions.
    "The ATB model was developed to complement experimental research in automobile crash environments and to provide a functional instrument for parametric investigations" [9]
  • Since the advent of the PC and the availability of PC versions of the ATB computer program, the ATB has been frequently encountered as an accident reconstruction tool used for demonstrative purposes in litigation matters. From McHenry "ATB should be used in forensics and accident reconstruction only as a tool to assist in understanding gross occupant kinematics. Any results or conclusions drawn from an ATB application related to detailed occupant kinematics involve so many approximations, estimates, and assumptions that they must be recognized as not being compatible with sound engineering practices and principles and, therefore, not scientifically supportable".
For additional information, please see: REFERENCES:
  • 1)James, Nordhagen, Warner, Allsop, Perl “Limitations of ATB/CVS as an Accident Reconstruction Tool”, SAE paper 97-1045
    2) McHenry “Analysis of the Dynamics of Automobile Passenger-Restraint Systems”, 7th Stapp Car Conference Proceedings, SAE, 1963-12-0017, 1966
    3) McHenry, Naab “Computer Simulation of the Crash Victim – A Validation Study”, SAE paper 660792, SAE 1966
    4) Cheng, Sens, Weichel, Gunther “An Overview of the Evolution of Computer Assisted Motor Vehicle Accident Reconstruction”, SAE paper 87-1881
    5) Consumer Reports, October 1961, Articles by Michelson and Tourin
    6) Michelson, Torin, "Consumer Union's Dynamic Tests of Seat Belts", 5th Stapp Automotive Crash and Field Demonstration Conference, September 1961
    7) Michelson, I., Aldman, B., Tourin, B. and Mitchel, J. "Dynamic Tests of Automobile Passenger Restraining Devices", Presentation to Committee No. 6, Department of Traffic and Operations, Annual Meeting of the Highway Research Board, Washington DC, January 7, 1963
    8) Bartz “Development and Validation of a Computer Simulation of a Crash Victim in Three Dimensions”, SAE Paper 720961, SAE, 1972
    9) Fleck, “An Improved 3-Dimensional Computer Simulation of Vehicle Crash Victims”, NHTSA, April 1975, NTIS PB-241 693, PB 241 694, PB-241 695
    10) Fleck, “Improvements in the ATB/CVS Body Dynamics Model”, 13th International Technical Conference on Experimental Safety Vehicles, S8-W-20, 1991
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