STISIM Drive (SDL) - WG - Wind Gust

Apply a continuous wind gust to the driver’s vehicle for a specified amount of time. This event allows you to put a pseudo-random wind gust into the scenario, thus causing the vehicle to drift off the road, and fluctuate in speed. The end result is that the driver must continually try to maintain the desired vehicle heading and speed by controlling the steering wheel and using the throttle.

This event requires a parameter file named WINDGUST.PAR in the STISIM/data directory, that contains the shape of the wind gust. The wind gusts that STISIM Drive generates are computed by summing a group of sine waves (sum of sines) together to produce a complex wave pattern. Any number of sine waves can be used and they can each have their own amplitude and period, the one restriction is that each sine wave must be an integer multiple of the total waves length. Therefore we require that you specify the number of periods that will occur during the wave, and that this number is an integer. The WINDGUST.PAR file has the following format:

Number of sine waves being used (n)
Total length of the combined sine wave, in seconds
Amplitude of wave 1, Period of wave 1
Amplitude of wave n, period of wave n

When STISIM Drive recognizes that the WG event will be used, it will automatically look for and try to load the information contained in the WINDGUST.PAR file. If it can not find WINDGUST.PAR, then an error message will be displayed and the WG event will be ignored.

The Wind Gust event is specified slightly differently if running with the Advanced Dynamics option. The amplitude of the wind gust in WINDGUST.PAR is specified as a true lateral wind speed in feet/second

EVENT PARAMETERS:

PARAMETER 1:	Steering wheel gain, in radians. Since the same gust parameters are used for both steering and throttle, STISIM Drive provides you with the ability to change the relative amplitude of each by specifying individual steering and throttle gains. Note: With Advanced Dynamics systems, this parameter is not used.
PARAMETER 2:	Throttle controller gain. Since the same gust parameters are used for both steering and throttle, STISIM Drive provides you with the ability to change the relative amplitude of each by specifying individual steering and throttle gains. Note: With Advanced Dynamics systems, this parameter is not used.
PARAMETER 3:	Run length multiplier. This parameter sets the total time that the gust will remain on. Since the gust is based on sine waves, STISIM Drive forces the gust to remain on until it is over. Parameter 3 is multiplied by the total length of the combined sine wave to determine the actual simulation run time where the wind gust will be active. Therefore, this should be an integer value greater than one.

EXAMPLE:

Sample WINDGUST.PAR file:

3
6
1,6
1,3
1,1

The sum of sines that will be used for this run includes 3 separate sine waves that will be summed together into 1 final wave. The total length of the final wave will be 6 seconds. Each of the 3 sine waves specified has an amplitude of 1 and their periods vary from 6 to 1. The sine wave with a period of 6 will have 6 maximum peaks occur during the 6 second wave, the wave with a period of 3 will have 3 maximum peaks occur, and the wave with 1 period will have a single maximum peak.

WG event:

1000,WG,2,.1,10

This example will add a wind gust to the scenario when the driver has traveled 1000 feet down the road (1000,WG). The sum of sines will consist of the wave data from the WINDGUST.PAR file with the steering gust being twice the sum of sines and the throttle gust being 1/10th (.10) the sum of sines. Since the sum of sines is 6 seconds long and the run time multiplier is 10, the wind gust will be in effect for a total of 60 seconds.