EDVTS

Name	EDVTS (Engineering Dynamics Vehicle-Trailer Simulator)
Description	EDVTS is a simulations of the response of a vehicle-trailer system (either a tractor-trailer or automobile-trailer) to driver braking and steering inputs. It is based on a program called TBSTT developed at the University of Michigan Transportation Research Institute, and includes extensions and refinements of the calculation procedures developed by EDC. As a simulation, the user provides a set of initial conditions and a table of driver inputs. EDVTS determines how the vehicle and trailer respond to the inputs by generation the path, velocity, acceleration, tire force, and other vehicle-trailer data as a function of time. EDVTS is a 4-degree of freedom (yaw plane) analysis; suspension effects are ignored. Load transfers are calculated on a quasi-static basis. The program is particularly well suited to low-to-moderate friction regimes. It also serves as an excellent first order approximation for higher friction road surfaces. Accident investigators can use EDVTS to determine how a driver may have lost vehicular control. By repeated adjustments of the braking and steering input tables, the user will converge on those driver inputs which match accident site evidence. It can also be used to study the handling effects due to changes in the vehicle weight distribution, wheelbase, track width, CG height, king pin location, trailer loading, single vs. tandem axles, tire friction and cornering stiffness, and other parameters.
Input	Title, Class, Configuration (vehicle/trailer tandems, duals, antilock), Initial Position (vehicle x, y, psi; trailer gamma) and Velocity (vehicle forward, lateral, angular; trailer angular), Simulation Time, Vehicle and Trailer Dimensions (inter-tandem, wheel base, track width, CG location --longitudinal, lateral, vertical), Vehicle and Trailer Inertias (weight, yaw moments), Payload Data (CG location, weight, yaw moment), Tire Data (peak/slide friction, slip at peak friction, cornering stiffness), Brake Force Table (each wheel), Steer Angle Table (front wheels). By selecting AUTOLOAD, the user can automatically load all of the required input data (except braking force and steer tables) for a given class vehicle. Various parameters can then be changed at the user's option prior to execution.
Output	Path (x, y, psi, gamma, turn radius, sideslip), Velocity (vehicle longitudinal, lateral, angular; trailer angular), Acceleration (vehicle U-dot, longitudinal, lateral, angular; trailer angular), Tire Loads (FX, FY, FZ), Load Transfers (dFX, dFY), Hitch Forces, Tire Slip Angles, Brake Forces, Steer Angle, Echo of Vehicle/Trailer Data.
Graphics	Vehicle Trajectory (various formats include continuous, variable time increment, freeze, and movie) with simultaneous display of key data; plotting of output data vs. time.
Other Features	Input session logic checks data as it is entered; the user may change any data prior to execution; the user may request a detailed explanation of the required input, including answer format and sample answer; rerun and file-saving options. Output session uses a spread sheet format, allowing the user to manipulate each data column into the position desired for viewing and/or printing; variable time increment of output; file-saving option.