Overview of CARAT-4, a Multi-body Simulation and Collision Modeling Program 2002-01-1566
CARAT (Computer Aided Reconstruction of Accidents in Traffic) is a Microsoft Windows® based simulation program. CARAT allows for simulation of pre-collision, collision, and post-collision dynamics in a graphical environment. CARAT can model cars, trucks, trailers and tractor/semi-trailers.
CARAT-3, released in the mid-90's, is a three degree-of-freedom (3 DOF) model, with three dependent DOF, and operates mathematically in a two-dimensional (2D) graphical environment. Vehicle graphics can be viewed in three dimensions (3D). CARAT-4 implements 3D multi-body models with 10 DOF for the car model, and up to 26 DOF for the truck and trailer model. CARAT is a time forward kinetic simulation, but can also be used to perform kinematic calculations forward and backwards in time. Both CARAT-3 and CARAT-4 implement a momentum-based collision algorithm.
This paper introduces and briefly describes the calculation models, and input parameters of CARAT-4 relating to the sprung masses, tire model, suspension, steering and braking systems. Graphical, tabular and plot output options are described.
Additionally, the RICSAC (Research Input for Computer Simulation of Automobile Collisions) tests were modeled by the CARAT collision algorithm, and the separation velocities and Delta-V's were compared with the test data, and SMAC calculations (as reported by McHenry).
CARAT-4 can be used to simulate automobiles and a range of heavy truck configurations. Potential applications of the program include analyzing and visualizing the effects of vehicle design changes and accident reconstruction.