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In prior studies researchers have been interested in automating the process by which the Simulation Model of Automobile Collisions (SMAC) is used to reconstruct an accident. The SMAC program requires an initial approximation of the impact speeds and the positions and orientations at impact. And with a SMAC reconstruction you can sometimes get a reasonably close match and then spend many hours on iterative runs trying to match as best as possible the overall body of physical evidence. The prior research on automation of SMAC (during the time period 1975-1980) was constrained by computer time and resources. Those research projects were performed on mainframe computers where all applications included charges for CPU time and memory resources. Today with gigahertz Pentium computers and unlimited memory, aside from the initial cost of the computer, the cost per SMAC run is virtually free and the time for a run is measured in seconds rather than minutes.

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.

A brief description and history of the Highway Vehicle Obstacle Simulation Model (HVOSM) computer program is presented. A number of references are cited that include applications of HVOSM and which present detailed descriptions of related extensions and refinements. This paper focuses attention on simulation developments of HVOSM and validation efforts specifically related to the simulation of collisions with concrete median barriers (CMB).

A brief description and history of the SMAC computer program, including its relationship to CRASH, is presented. The rationale for a continued interest in the SMAC approach to reconstruction is discussed. Modifications and refinements that have contributed to the current capabilities of SMAC-87 are briefly described, representative results of applications are presented and planned future developments are defined.

A revised damage analysis procedure for CRASH, which includes restitution effects, is described. The proposed calculation procedure has the potential capability of (1) improving the delta-V accuracy in low-speed collisions and (2) segregating stiffness and restitution properties. The analytical approach can provide a basis for refinement of the categorization of vehicles through its use of additional crush property descriptors. Sample results from applications of a prototype computer routine are presented and compared with corresponding results from the original damage routine of CRASH. The reported research has been supported by McHenry Consultants, Inc.

An unusual application of a computer simulation of automobile dynamics to the design of a thrill show stunt is described. The rationale for development of the simulation for highway safety applications is discussed and the general analytical approach is described. Computer graphics displays of simulation outputs, consisting of detailed perspective drawings of the vehicle and terrain features or obstacles at selected intervals of time during a simulated maneuver, are presented. For the presentation of the paper, computer graphics displays of simulation outputs will be animated through the use of motion picture film. Also, motion picture coverage of both developmental tests and public performances of the Astro Spiral Jump will be shown.

The Simulation Model of Automobile Collisions (SMAC) computer program has been developed for the purpose of achieving uniformity in the use of analytical techniques for interpretation of physical evidence in investigations of highway accidents. The comprehensive output information of the SMAC program (kinematics, tire tracks, and vehicle damage) permits extensive, detailed comparisons with physical evidence in the iterative runs used to achieve a “best fit,” and the predicted vehicle responses provide a basis for relatively refined categorization of occupant exposures. The generality included in the inputs of the SMAC program permits approximation of the effects of driver control inputs, damage to vehicle running gear, and traversal of terrain zones with different friction properties. The analytical approach is outlined, and specific assumptions are defined. Comparisons are presented between analytical predictions and results of staged collisions.

A digital computer simulation of complex, three-dimensional dynamics of automobiles on irregular terrain is described which is suitable for studies related to vehicle braking systems and to the driving task, including the upper limits of control as well as the linear ranges of operation. The reported simulation is an extended version of an earlier, validated mathematical model. A number of refinements and extensions of the analytical treatments of tire forces, suspension properties, and terrain definitions, have been incorporated. Also, analytical representations of the braking system and driveline, and approximations of rolling resistance and aerodynamic drag, have been introduced. Sample outputs of the modified computer program are presented and discussed.

AN ELEVEN-DEGREE-of-freedom nonlinear mathematical model of an automobile traversing a variety of irregular terrain features and encountering a variety of roadside obstacles has been formulated and programmed for a digital computer. The primary objective of the described research has been to develop analytical means of evaluating existing and proposed roadside energy conversion systems. However, the developed computer simulation also has potential applications in the reconstruction of single vehicle accidents and in studies of the driving task at the upper limits of vehicle control. A unique feature is the simulation of combined cornering and ride motions. In its present form, the computer program includes open-loop evasive maneuvers. The results of a review of single vehicle accident statistics and measurements of structural load-deformation properties of automobiles, performed within this research program, are both presented.