Swept Sine
A Swept Sine event simulates a vehicle driving at a constant speed with a sinusoidal steering input of constant magnitude but increasing frequency applied.
Output Requests are included to measure the vehicle state variables, tire forces, and tire state variables. The Altair Driver steers the vehicle and maintains constant speed.
The Swept sine event is supported by the Cars & Small Trucks and Heavy Trucks vehicle libraries. Automated output reports are available to plot the results.
The Swept sine event follows the ISO +7401-2003 - Road vehicles — Lateral transient response test methods — Open-loop test methods.
Parameters
Parameter Name | Description |
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Units | Describes the Length, Velocity, and Acceleration units.
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Velocity | The constant speed that the vehicle attempts to maintain during the event. |
Steer amplitude | Amplitude of the steering input (degrees). |
Frequency change rate | The rate of change of frequency (hz/sec) of the sine wave function applied to the steering wheel. |
Minimum frequency | The minimum (initial) frequency sine wave that is applied to the steering wheel. |
Maximum frequency | The maximum (final) frequency sine wave that can be applied to the steering wheel. |
Start time | The start time of the sine wave. |
End Time | End time of the simulation (calculated using the start time, the frequency rate, and the max and min frequencies). |
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
- 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.
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
- 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.
- View path centerline: Enables the visualization of the event path.
- 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
Report Name | Report Signals |
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Steering Input and Acceleration |
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Vehicle Velocities |
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Vehicle Slip Angles |
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Roll Angle |
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Steer/Suspension Travel |
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Steering, roll and torque |
|
Vehicle Slip vs. Acceleration |
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Steering Wheel Angle vs. Vehicle Sideslip Angle | |
Tire Lateral Slip |
|
Vertical Tire Forces |
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Lateral Tire Forces |
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Longitudinal Tire Forces |
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Wheel Aligning Torques |
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Vertical Tire Forces vs. Lateral Acceleration |
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Lateral Load Transfer |
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