VePAS - Version 2.0
The Vehicle Performance and Analysis Simulation is a graphical
six degree-of-freedom simulation package capable of modeling a
large variety of vehicles such as passenger cars, trucks, and
high-performance vehicle, as well as, public transportation and
recreational vehicles (2WD or AWD). VePAS combines land-vehicle
dynamics with graphical software capabilities to form a comprehensive,
user-friendly tool for advanced vehicle engineering.
User Interface
VePAS features a mouse/menu user interface and a graphical display
mode. The menu interface allows you to view the input vehicle
specifications, activiate/deactivate output data files, plot VePAS
data elements, modify simulation interface parameters, and access
help information. The graphical display mode provides you with
attitude viewports, accelerometers, a speedometer and tachometer,
and run-time data elements based on the modeled scenario.
Scenario Capabilities
VePAS provides you with the ability to test a component or complete
vehicle design under performance, ride, stability & control, handling,
or braking situations. In addition, VePAS contains a user-defined
Driver environment which allows you to govern vehicle speed,
steering controls, throttle controls, transmission gear changes, and
braking response.
Wind Model
The VePAS program incorporates an environment wind model. The wind
model can be used to perform stability & control vehicle analysis,
or for including realistic environmental conditions in a test
scenario which may exist during an actual vehicle test.
Fuel Economy Prediction
The VePAS engine model determines the fuel flow during all vehicle
operational states. The fuel flow is based on engine speed and
load conditions. VePAS uses engine fuel flow to determine an estimate
of fuel economy. Fuel economy results can be plotted during run-time
to provide a graphical view of fuel consumption during different
phases of vehicle operation.
Anti-lock Brake System (ABS)
VePAS includes a vehicle anti-lock brake system which consists of
two independent subsystems for front and rear wheel brake controls.
Each subsystem consists of a brake torque application control unit,
a wheel sensor, a wheel lock predictor, a brake release modulator,
and a reselection controller.
Drivetrain Dynamics
VePAS allows for user-designed drivetrain modeling. The program
utilizes the dynamic characteristics of the drivetrain you define
by the initial vehicle specifications. VePAS uses these
characteristics in determining the dynamics of horsepower or torque
losses due to accelerating the rotating components of the drivetrain.
The drivetrain model consists of wheels and tires, an engine, a
transmission, and drivelines.
Three-Dimensional Road
For ride quality modeling and vehicle design analysis, a
three-dimensional road model is included. The road model allows for
transient vehicle ride analysis. You can construct the road model
after specifying a modification to the existing road profile. Initially,
the road is defined as a two-dimensional, flat, infinite plane. When
you modify this plane, you define impulse or ramp style ground inputs.
You can define road impulses on both the driver and
passenger sides of the vehicle.
Spring and Damper Elements
The vehicle model includes dynamics relating to linear springs and
dampers. A spring and damper is located at each corner of the vehicle
defined by the wheelbase and front/rear track. Also, you define the
stiffness for each spring and the viscous damping rate for each
damper element.
