EDVDS (Engineering Dynamics Vehicle Dynamics Simulator)
EDVDS is an HVE-compatible 3-D simulation of the dynamic response of a commercial vehicle to driver inputs and 3-D road conditions. A tow vehicle and up to three trailers may be simulated. EDVDS is an extended version of the Phase 4 program developed at the University of Michigan. Extensions include full 3-dimensional simulation capability, an updated suspension model with jounce/rebound stops, an updated tire model that supports 360° slip angles and 2-step radial tire stiffness, and the ability of each tire to respond to an arbitrary 3-D terrain. These advancements extend the capabilities of researchers to study real world highway safety issues involving commercial vehicles.
The user enters initial position, velocity and driver controls (steering, braking, throttle) for the tow vehicle. Trailers and dollys are automatically positioned according to connection locations. An optional payload may be assigned for the tow vehicle and each trailer. EDVDS then predicts the motion of each vehicle's sprung mass (X, Y, Z, roll, pitch, yaw), the motions of the unsprung masses (wheel deflections, spin velocities), suspension dynamics (spring forces and deflections, axle accelerations), tire dynamics (forces, moments and slip angles at the tire/road interface), and current brake system parameters at each wheel (air pressure, brake torque, lining temperature).
Vehicle design engineers and safety researchers can use EDVDS to perform detailed studies involving vehicle handling and controllability. Typical human factors issues include driver inputs and speed; vehicle factors include brake system and suspension design, loading conditions, and tire properties; and environment factors include superelevation and slippery road conditions.
EDVDS employs full 3-dimensional engineering models with up to 23 degrees-of-freedom for each vehicle. The program supports up to 4 axles per vehicle, solid and tandem axle suspension-types with inter-tandem load transfer, and single and dual tires. Combination vehicles are connected using fixed and converter dollys with rigid or hinged drawbars.
The small angle assumption in the Phase 4 program has been eliminated in EDVDS, allowing for simulation of complex roll-over events. In addition, EDVDS has been extended to include a comprehensive drivetrain model with engine performance parameters, multi-gear transmissions and differentials.
Tire vs terrain interaction is modeled transparently to the user. This powerful capability allows the user to create a detailed, 3-D environment (using HVE's 3-D Editor or any popular modeling package), then drive a vehicle on it. At each timestep, the EDVDS tire model queries the environment to use the current elevation, surface normal vector and friction beneath each tire.