STISIM Drive (SDL) - BSAV - Begin Block Save

Begin saving data that will be stored in the output file that is created at the completion of the simulation run. This option combined with the ESAV event allows you to save a block of data at any time during the simulation run. Specifying the BSAV event tells the program to begin collecting the data, to stop collecting data, you must use the ESAV option, or use a new BSAV event. You will specify what data is collected based on a list of possible variables, and these variables can be changed from one data block to the next. The data that is stored will be saved in fixed length fields that will make it easy to pull the data into a spreadsheet or other analysis packages.

EVENT PARAMETERS:

PARAMETER 1:

Save data options. To specify the save data option, set parameter 1 to one of the following:

0 - Save data based on how far the vehicle has traveled since the last time the program saved an increment of data. If you use this option, the save increment is entered in feet. The vehicle may actually travel farther then the specified amount before the data is saved. This is because the distance the vehicle travels is based on the speed of the vehicle and the frame time for the simulation run. As soon as the save increment has been exceeded the program will save the data.

1 - Save data based on the number of seconds that have elapsed since the last time the program saved an increment of data. If you use this option, the save increment is entered in seconds. For best results, try to make this number be an integer increment of the frames per second parameter specified in the system configuration.

PARAMETER 2:

The save increment. As was discussed above, if you are using option 0 from above, then you will enter this parameter in the units of feet. If you are using option 1 from above, then this parameter will be in seconds. The internal timer is accurate to approximately a millisecond, therefore there may be some round off error when trying to save the data. For this reason you may wish to subtract a small fraction of the time increment. For example, if you would like the data to be saved every .1 second, you may want to specify the save increment as .099 or .0995.

PARAMETER 3:

This is a string variable that allows you to mark a particular data block with its own individual title. This parameter is intended to help you with your data reduction needs. Labeling a block of data with a descriptive name makes it easy to search through the data that was collected and find the block of data that you are trying to find.

PARAMETERS 4-n:

These parameters represent the data variables that you would like saved. You specify the data that will be collected by listing the variable numbers that correspond to the variables you would like to save. The following lists the variables that may be collected and their variable numbers:

1.       Elapsed time since the beginning of the run (seconds)

2.       Driver’s longitudinal acceleration (feet/second²)

3.       Driver’s lateral acceleration (feet/second²)

4.       Driver’s longitudinal velocity (feet/second)

5.       Driver’s lateral velocity (feet/second)

6.       Total longitudinal distance that the driver has traveled since the beginning of the run (feet)

7.       Driver’s lateral lane position with respect to the roadway dividing line, positive to the right (feet).

8.       Vehicle curvature (curved path the vehicle is following based on the driver's steering and speed) (1/foot).

9.       Current roadway curvature (1/foot)

10.   Vehicle heading angle (degrees)

11.   Steering wheel angle input (degrees)

12.   For simple dynamics:

Longitudinal acceleration due to the throttle (feet/second² )

For advanced dynamics:

Throttle input (0 to 1, with 0 being no throttle input and 1 being full throttle input)

13.   For simple dynamics:

Longitudinal acceleration due to the brakes (feet/second² )

For advanced dynamics:

Brake pedal force (pounds)

14.   Current traffic signal light position:

0 - No signal light present
1 - Green light
2 - Yellow light
3 - Red light

15.   Horn indicator, 0 if horn button is pressed

16.   Left turn signal indicator, 0 if turn indicator is on

17.   Right turn signal indicator, 0 if turn indicator is on

18.   Running compilation of the crashes that the driver has been involved in. The number shown in the file is created by adding the number that corresponds to the type of accident, to the current total. This allows you to easily look at the number and tell whether an accident occurred, and if so, the type of accident. The accidents have the following numbers:

1 - Vehicle collisions
2 - Off road collisions
3 - Collisions with pedestrians

For example, if the current number shown for this parameter is 10, then on the next line of the STISIM Drive data file, this parameter has changed to 13, then an accident occurred and it was a collision with a pedestrian (13-10=3 therefore a pedestrian was run over).

19.   Roadway traffic data. For each vehicle that is in the roadway display, this parameter will save the following data:

Vehicle identification number

Difference in longitudinal speed between the driver’s vehicle and the roadway vehicle (feet/second)

Longitudinal position of the roadway vehicle with respect to the driver’s vehicle (feet)

Lateral position of the roadway vehicle with respect to the roadway’s dividing line (feet)

There is a slight problem when saving this particular data. This option will save data for every other roadway vehicle that is being displayed and as vehicles drop out of the display, their data will no longer be collected. This can cause shifting in the data file because as one vehicle drops out, all of the subsequent columns move over. For this reason we recommend that if you will be collecting other vehicle data, you always make 19 the last variable in the variable list.

20.   Time code for systems that are using a Horita time code stamper. This allows you to place the time code from the stamper hardware into the data file and onto a video tape so that your data can be correlated. Check with STI for more details on this hardware option. The format for the time display is:

HH:MM:SS:FF

Where HH is the hours, MM the minutes, SS the seconds, and FF is the video frames (1-30).

For information on the video setup, refer to the video portion of the hardware configuration discussion.

21.   Head tracker data. This is only available if you are using a head mounted display with a head tracker and will provide the heads orientation:

Head pitch ( Up and down motion, in degrees, positive up)
Head roll (Tilt left and right, in degrees, positive to the right)
Head yaw (Turning side to side, in degrees, positive to the right)

22.   Data marker flag. If this is set and you simultaneously press the Alt and M keys during the run the marker will change from 0 to 1 or from 1 to 0. This allows you to view the driver and then mark the data file if you see something that you may want to check later. Remember this only toggles a flag between 0 and 1, so you will have to be careful in how you use it. This means that once the flag is set, you have to press Alt and M again to return the value to 0.

23.   Driver's longitudinal velocity (miles/hour)

24.   Vehicle yaw rate (radians/second)

25.   Current transmission gear

EXAMPLES:

100,BSAV,0,100,CALVIN,1,6,4,18,19
100,BSAV,1,.0995,THADDEUS,1,6,4,18,19

When creating your simulation environment, one of the first steps that you should take is to determine what data variables that you would like to collect. Once you know this, you will either use the BSAV/ESAV or RMSB/RMSE combinations to collect the data and save it at the completion of the run.

The first example shown above will begin to save data after the driver’s vehicle has traveled 100 feet down the road. The subsequent data that will be collected will be based on the longitudinal distance that the vehicle has traveled. Every 100 feet or so (remember it may not allows be exactly 100 feet, see the Miscellaneous Information section), the program will save the specified variables. When the final STISIM Drive Data File is created at the completion of the run, the data from this BSAV statement will be found in the block named CALVIN and will include data for the elapsed time since the start of the run, longitudinal distance from the start of the run, driver’s longitudinal velocity, total number of accidents, and data for any other roadway vehicles that are displayed (1,6,4,18,19).

The second example will begin to save data after the driver’s vehicle has traveled 100 feet down the road. The subsequent data that will be collected will be based on time and will be collected approximately every .0995 seconds (1,.0995). Assuming that the frame time is 20 times a second (.05 seconds), this data collection rate should allow data to be collected every 10th of a second. Otherwise, the data variables may occasionally be saved after an interval of .15 seconds. When the final STISIM Drive Data File is created at the completion of the run, the data from the above statement will be found in the block named THADDEUS and will include data for the elapsed time since the start of the run, longitudinal distance from the start of the run, driver’s longitudinal velocity, total number of accidents, and data for any other roadway vehicles that are displayed (1,6,4,18,19).