Sinusoidal Steering

A Sinusoidal steering event simulates a vehicle driving at a constant speed while a sin wave input is applied to the steering wheel.

The event is used to simulate the On-center steering test described in SAE paper 840069. Standard vehicle outputs are included in the event. Body state variable output requests (displacement, velocity, acceleration) are included in the body system and tire output is included in the Tire System. A plot template is available to plot the results.

The Sinusoidal steering event is supported by the Cars & Small Trucks and Heavy Trucks vehicle libraries. Automated output reports are available to plot the results.

The Sinusoidal steering event follows the SAE 840069 – Objective Evaluation of On-Center Handling Performance.

Parameters

Parameter Name Description
Units Describes the Length, Velocity, and Acceleration units.
  • Length (Model, m, ft)
  • Velocity (Model, m/s, km/h, mph).
  • Acceleration (Model, m/s2, g’s).
Velocity Initial vehicle velocity.
Steer amplitude Amplitude of the steering input (degrees).
Frequency The frequency of the steering input (hertz).
Start time Initial time of the sinusoidal steering application (seconds).
End time Absolute end time of the event (seconds).

Controller Settings

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

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.

Automated Output Report

The list of outputs present in Sinusoidal steering event report are as follows:
Report Name Report Signals
Steering Input and Accelerations
  • Steering Wheel Angle vs. Time
  • Steering Wheel Torque vs. Time
  • Lateral Acceleration vs. Time
  • Roll Angle vs. Time
Longitudinal Tire Forces
  • Yaw Rate vs. Time
  • Vehicle CG Displacement vs. Time