Road Course Drive

The Road input for this event is provided through a road property file. This event offers flexibility in the kind of road that can be used in the simulation. A road property file can be created in the appropriate format that meets the desired requirements and it must be compatible with the tire model in the full vehicle model.

The Road Course Drive event is supported by the Cars & Small Trucks, Heavy Trucks, and Two-Wheeler vehicle libraries.

Parameters

Parameter Name	Description
Path profile	Defines the path used by the Altair Driver in the event. Three options are available: Straight Line: the vehicle follows a straight line path. Road Centerline: the vehicle follows the specified road centerline (Road centerline is generated in a DDF file before the start of the simulation). Curve: Option to attach an MV x-y curve as the path input. Units – Units of curve inputs [Model, m, ft] Curve – MV curve attachment Interpolation – Selection for interpolation scheme [AKIMA,CUBIC, LINEAR, QUINTIC]
Velocity profile	Defines the velocity profile used by the Altair Driver in the event. Two options are available: Constant: vehicle follows a constant demand velocity input. Curve: Option to attach an MV x-y curve as the velocity input. Units – Units of curve inputs [Model, m/s, km/ h, mph] Curve – MV curve attachment Interpolation – Selection for interpolation scheme [AKIMA,CUBIC, LINEAR, QUINTIC] Independent variable – x values signal type [Time, Distance]
End time [s]	End time for the simulation.

Controller Settings

Non-leaning events (Cars/Trucks)

LONGITUDINAL – TRACTION CONTROLLER SETTINGS

Use additional control: Enables the additional feedback control for the traction control. The gains for the controller can be edited by toggling this check box.

Kp	Proportional gain for the feedback PID controller
Ki	Integral gain for the feedback PID controller
Kd	Derivative gain for the feedback PID controller

LATERAL – STEERING CONTROLLER SETTINGS

Altair Driver uses Feedforward steering controller for non-leaning vehicles like Cars and Trucks. The following settings can be edited by the user.

Look ahead time	Look ahead time for the feedforward model to evaluate future states of the vehicle
Prediction step size	Maximum step size, used by the Driver feedforward steering model

For more information see the Altair Driver Mathematical Methods topic.

Leaning events (Two-wheelers)

LONGITUDINAL – TRACTION CONTROLLER SETTINGS

Use additional control: Enables the additional feedback control for the traction control. The gains for the controller can be edited by toggling this check box.

Kp	Proportional gain for the feedback PID controller
Ki	Integral gain for the feedback PID controller
Kd	Derivative gain for the feedback PID controller

LATERAL – STEERING CONTROLLER SETTINGS

The Lean PID and Lateral Error PID controllers only apply to leaning vehicles (for example, motorcycles and scooters).

Steer control: Control mode for steering can be switched between ‘MOTION’ and ‘TORQUE’

Lean control

The Lean PID takes as input a demand lean angle and outputs front fork (steering) angle. For open loop events the lean angle demand is a function of time. For closed loop path following events the demand lean angle is computed based on the vehicle speed and the path curvature with a correction for lateral path error.

Kp	Proportional gain for the lean controller
Ki	Integral gain for the lean controller
Kd	Derivative gain for the lean controller

Lateral error control

The Lateral Error PID takes as input the predicted lateral path error and outputs an increment to the demanded lean angle. The lateral error is computed by predicting the vehicle’s lateral position relative to the path by the look ahead time in the future. The Lateral Error PID acts to lean the vehicle toward the path.

Look ahead time	Look ahead time for the feedforward model to evaluate future states of the vehicle
Kp	Proportional gain for the lateral error controller
Ki	Integral gain for the lateral error controller
Kd	Derivative gain for the lateral error controller

For more information see the Leaning Two and Three Wheeler Vehicles and Gain Tuning for Leaning Two and Three Wheeler Vehicles topics.

Signal Settings

Use the signal settings to set minimum, maximum, smooth frequency and initial values for Steering, Throttle, Brake, Gear, and Clutch signals output by the driver.

The smoothing frequency is used to control how fast the Driver changes signals. Only closed loop control signals from the Driver are smoothed. Open loop signals are not smoothed.

Road Settings

Three options are available to specify the road in the event, Flat Event, Road File, and Tires.

Flat Road

Uses a flat smooth road for the event with no required road file.

When the Flat Road is selected, the Graphics Setting option is available with the following parameters:

View path centerline: Enables the visualization of the event path.
- This check box is disabled for open loop events without a path.

View grid graphics: Enables the visualization of the road grid graphics.

When view grid graphics check box is toggled, road grid parameters can be edited in the Grid Settings tab.

Grid length	Defines the length of the road. Enter a positive value in the model units.
Grid Width	Defines the width of the road. Enter a positive value in the model units.
Grid X offset	Gives a distance offset to the road graphics in the longitudinal direction. Enter a positive value in the model units.
Grid Y offset	Gives a distance offset to the road graphics in the lateral direction. Enter a positive value in the model units.

Road File: The road file option enables the selection of a road file to be used in the event. Using this option, all tires in the model consider the event specified road file instead of the file included in the tire entities.
Tires: Using Tire as road selection option, the road file specified in the tire entity is used in the events simulation.

Troubleshooting Tips

The road property file should be compatible with the tire property file that is used in the vehicle.
The units in the path profile will be used when the independent variable in the velocity profile is set to Distance.
The MotionView curve entity used to define the velocity profile should have the same units as specified in the Units field.
The road centerline option will work (to generate the ddf), only if the road property file provided can be used by the Roads tools functionality.