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: 13.
For
simple dynamics: 14.
Current
traffic signal light position: 0 - No signal light present 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 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) 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).