STISIM Drive - Data File
At the end of each
simulation run, the program creates a data file containing various data
acquired during the simulation run. This file will always be created and can be
quite lengthy and take up a lot of disk space. The file that is created will
have the name specified in the Output Data File field from STISIM Drive's main
window and will be stored in the subdirectory specified in the STISIM Drive configuration. Each STISIM Drive Data File will
vary slightly depending on the scenario that was run. For discussion purposes
it is easiest to break the Data File into sections. There are eight general
sections that may appear in the file. They are:
GENERAL_INFORMATION
BSAV/ESAV_BLOCK_DATA
RMSB/RMSE_DATA_BLOCKS
PI_DATA_BLOCKS
Divided Attention Data
DI/DO_DIGITAL_I/O_DATA
Time To Collision
DRIVER_MISTAKES
The general information
includes the driver’s identification number (only used if set in the
simulator's configuration), the date the simulation was run, the time of day
when the simulation run began, and the name of the events file that was used.
Additionally, if any driver information was specified (Run
Option), then this information will also be included in the general
information portion of the data file. Next, the data file will include a
complete listing of the scenario that was run in the output file. This is a
listing of the events file, and is included to document the scenario the driver
was given. This makes the file and data that is collected self documenting.
The block data section
contains all of the data collected when using the BSAV
and ESAV event options. The data collected are
placed in the file IN THE ORDER THAT THEY ARE SPECIFIED WHEN THE EVENTS WERE
CALLED. Remember that when you use the BSAV/ESAV events, you specify the variables that will be
saved to the data file, therefore, the format of the BSAV/ESAV blocks will
always be changing. In general, the format for the data in this section of the
file is as follows:
Block number and user
defined block name, number of time increments collected
User defined data block
(data that you specified)
Off road accidents,
Collisions, Pedestrians hit, Speeding tickets, Red lights ran, Speed limit
exceedances
Each of the variables that
can be saved in the user defined data block is specified using the BSAV event from the SDL. When
the program saves the data to the data file, it will automatically format the
variables so that the resulting file will be evenly collimated so that the data
can be easy imported into other programs such as spreadsheets. The block number
is automatically assigned by the program after each block is saved. The user
defined block name allows you to assign each block of data a unique name that
can be used later to sort your data. The block name is one of the parameters defined
in the BSAV event. After the user defined data
block has been saved, the program will automatically include some additional
information at the bottom of the block before it begins to save a new block of
data. This data includes the number of off road accidents occurring when the
driver steers the vehicle too far off the road. The number of collisions that
occurred when the driver ran into another vehicle. This includes vehicles in
either lane of traffic, cross traffic vehicles, and vehicles in the rear view
mirror. This is followed by the number of pedestrians that the driver ran over,
the number of tickets that were issued because the driver was speeding when a
police officer was present, and the number of tickets due to running a red
light. The final data field contains the number of times the driver exceeded
the posted speed limit.
The RMS data section
contains the data collected during the RMS segments of the simulation. The RMS
segments are controlled by the event specifiers RMSB
(RMS begin) and RMSE (RMS end) as specified in
the SDL. The data that is collected during the simulation run will be placed in
the data file in the same order that it was taken during the run. Although the
term RMS is used in this section, the data that is computed is not truly RMS
data, it is really just the standard deviation.
The format for the RMS
output data is as follows:
RMS data in a [curve or
straight away]
Number of off road accidents, Number of collisions
Correct responses, Incorrect responses, No responses
Average time of response, RMS time of response (seconds)
Average lane position, RMS lane position (feet)
Average steering wheel rate, RMS steering wheel rate (degrees/second)
Average vehicle heading angle, RMS vehicle heading angle (radians)
Average vehicle curvature, RMS vehicle curvature (1/foot)
Average throttle activity, RMS throttle activity (g's/second)
Average longitudinal acceleration, RMS long. acceleration (g's)
Average longitudinal speed, RMS longitudinal speed (miles/hour)
The number of off road
accidents only counts the number of times a crash occurs when the driver's
vehicle has left the roadway. The number of collisions refers to all accidents
when the driver's vehicle collides with another vehicle, the pedestrian, or a
vehicle approaching from the rear and displayed in the rear view mirror. The
correct, incorrect and no responses data comes from any divided attention
events that are called for during the RMS segment. The no responses data is the
number of times the driver was required to reply, but did not. The time
response data refers to the amount of time it took the driver to react to the
divided attention task. The lane position data refers to the location of the
driver's vehicle with respect to the roadway’s dividing
line. The steering wheel rate is how fast the driver is turning the
steering wheel while doing steering maneuvers. The vehicle heading angle is the
angle that the vehicle is pointing relative to its initial position. The
vehicle will always start with a heading angle of 0 and the angle is measured
relative to this. Although the display will show the vehicle pointing straight
ahead its heading angle will change based on the roadway and any manuevering
taking place. For example if there is a 90 degree curve the heading angle
should change by roughly 90 degrees (1.57 radians). The vehicle curvature is a
measure of the path the vehicle is following (due to the driver's steering
inputs and speed). If the driver is tracking perfectly, then the vehicle
curvature and the roadway curvature (specified with the C
event in the SDL) should be exactly the same. The throttle activity data provides
some indication of how much the driver is using the throttle. It is measured in
terms of forward acceleration (not total acceleration) per second. By measuring
the throttle activity this way, data is comparable over all simulator systems.
If a measure of counts per second was used the data may not be comparable
because one system may have 10 times the number of counts on the throttle input
than another system. Longitudinal acceleration is the total acceleration due to
throttle, braking and drag. The longitudinal speed is the vehicle's velocity.
Correct responses are defined
as the number of times the driver responded correctly to the divided attention
symbols displayed in the "mirror". Incorrect responses are the number
of times the driver responded incorrectly to the divided attention symbols, and
the No responses parameter indicates the number of times the driver failed to
respond to the divided attention symbols. The remainder of the data presents
the time it took the driver to respond to the symbols, the vehicle condition,
and its position on the road. The average and RMS data is only averaged for the
current segment and does not include previously obtained data.
One final note about the
RMSB/RMSE data. The term RMS we are referring to is the Root Mean Square
of the deviations. This is more commonly know as standard deviation. Therefore
anytime the term RMS is used, you may simply substitute standard deviation and
the results will be the same.
If you are using the
performance index option (PI event), the output
file will have a slightly different format. First, the data from all the other
events will be displayed in the file (this includes data for DI and DO, divided attention (DA) tasks, and driver mistakes).
Next, data for each individual segment will be shown. This data contains the
mean and RMS values for the following variables:
Divided attention task
response time (seconds)
Lane deviation (feet)
Steering wheel rate (degrees/second)
Heading angle (degrees)
Vehicle curvature (1/foot)
Throttle activity (g’s/second)
Longitudinal acceleration (g’s)
Longitudinal speed (miles/hour)
At the end of the
simulation run, segment, mean and RMS values are computed for each of the
variables shown above. Additionally the following data will also be presented
for each segment:
Segment Number
Number of correct divided attention responses during the segment
Number of incorrect divided attention responses during the segment
Number of missed divided attention responses during the segment
Number of accidents during the segment
All of this data is then
used to compute a final performance index in each of 6 separate categories. The
performance index for each category is computed using a combination of performance
index coefficients (found in the STAT.DAT file in the Parameter_Files
directory, usually C:\STISIM\Data\Parameter_Files), and 20 different segment
variables whose mean and RMS values are computed. For each criteria, the
program will write the mean and RMS values for all 20 segment variables into
the simulation output file, and then display the computed performance index and
the passing index separated by a slash. If the computed index (value to the
left of the slash) is lower than the established index (value to the right of
the slash) then the driver has passed that criteria. If the computed index is
higher than the established index, the driver has failed the criteria. If the
driver fails any of the 6 criteria, they automatically fail the entire simulation
run. In either case the last line in the performance index data block will
display a message giving the overall results.
As was mentioned above,
there are 6 different categories that the driver will be judged on. The
categories as they appear in the data file are:
Vehicle RMS curvature
Divided attention RMS response time
Throttle RMS activity
Steering RMS activity
Vehicle RMS longitudinal speed
Vehicle average longitudinal speed
These categories,
performance index coefficients, segment variables, and the established passing
indices, were all determined for truck driver fatigue. The 20 segment variables
that are used to compute each of the driver's performance indices are as
follows (they are listed as they appear in the simulation output file):
Number of correct
divided attention responses
Number of incorrect divided attention responses
Number of divided attention responses where the driver did not responded
Number of collisions
Average time for a secondary response (seconds)
RMS for a secondary response (seconds)
Average lane deviation (feet)
RMS lane deviation (feet)
Average steering wheel (degrees/second)
RMS steering wheel rate (degrees/second)
Average vehicle heading angle (degrees)
RMS vehicle heading angle (degrees)
Average vehicle curvature (1/foot)
RMS vehicle curvature (1/foot)
Average throttle activity (g’s/second)
RMS throttle activity (g’s/second)
Average longitudinal acceleration (g’s)
RMS longitudinal acceleration (g’s)
Average longitudinal speed (miles/hour)
RMS longitudinal speed (miles/hour)
The STAT.DAT file contains
the established performance index values, as well as the parameter coefficients
that will be used to compute the driver's indices. The STAT.DAT has the
following format:
Dummy value that is no
longer used
Number of criteria that will be used
Mean coefficient for segment variable #1, RMS coefficient for segment variable
#1
Mean coefficient for segment variable #2, RMS coefficient for segment variable
#2
·
·
·
Mean coefficient for segment variable #19, RMS coefficient for segment variable
#19
Mean coefficient for segment variable #20, RMS coefficient for segment variable
#20
Established index for criteria #1
·
·
·
Established index for criteria #6
Once again, when the term RMS
is used what we are referring to is the Root Mean Square of the
deviations. This is more commonly know as standard deviation. Therefore anytime
the term RMS is used, you may simply substitute standard deviation and the
results will be the same.
The section for the divided
attention task contains the data for each individual response. For each symbol
displayed, the program records the driver's response and how long it took the
driver to respond. The format for this section is as follows:
Symbol (LT,RT,LH,RH),
Correct response, Response time, Elapsed time from the start of the run
The symbol is the specifier
read from the events file. The correct response will be 0 if the driver
responded correctly, 1 if the driver responded incorrectly, and 2 if the driver
did not respond at all. The driver response time is measured in seconds, and
the elapsed time is measured in seconds. The divided attention option must be
specified using the Other tab box from the STISIM Drive
configuration and then is activated using the DA event.
The section for the digital
input tasks contains the data for each individual response. For each DI event, the program records the driver's response
and how long it took the driver to respond. The format for this section is as
follows:
Expected response
binary, Actual response binary, Expected response decimal, Actual response
decimal, Correct response, Response time, Elapsed time from the start of the
run
The expected response is
the response read from the events file. The actual response is the response the
user gave. The values that are displayed for the expected and actual responses
are shown as both 12 bit binary numbers and regular decimal numbers. The binary
representation allows you to easily compare the expected result with the actual
result and shows you which bits were being activated. The correct response
parameter will be 0 if the driver responded correctly, 1 if the driver
responded incorrectly, and 2 if the driver did not respond at all. The driver
response time and the elapsed time from the start of the run are measured in
seconds.
Time to collision data
refers to how close the driver’s vehicle gets to other vehicles in the driver's
path. If the time to collision flag is set (Others tab box
from the STISIM Drive configuration option), STISIM Drive will collect this
data and save it to the data file. The data will only be collected for vehicles
specified with the A and V
events. In the data file, the time to collision data is broken into 2 different
sections, one for the vehicles heading in the driver's direction, and one for
the vehicles in the opposite direction. For each of these, the program records
the vehicle’s number, the minimum range between the driver’s vehicle and the
other vehicle, the minimum time until the 2 vehicles would have collided, and
finally the elapsed time (in seconds) since the beginning of the run when the
minimum time to collision occurred. Time to collision values of 0 mean the
vehicles collided. The format for this section is as follows:
Vehicle number, Minimum range, Minimum time to collision, Elapsed time from the start of the run
The final section of the
data file contains a listing of the mistakes the driver has made during the
run. This section is presented in 2 parts. The first contains a cumulative
total of all of the driver’s mistakes and responses. The second section is
comprised of a list of each individual speeding ticket, off road accident,
collision, pedestrian hit, and red light that was run; and includes the time
and longitudinal distance into the run where the mistake occurred. The first
part will be displayed as follows:
Total number of off road
accidents
Total number of collisions
Total number of pedestrians hit
Total number of speed exceedances
Total number of speeding tickets
Total number of traffic light tickets
Total number of stops at traffic lights
Total number of correct DA responses
Total number of incorrect DA responses
Total number of DAs with no response
Total run length
The total number of
accidents includes instances where the driver steered far enough off of the
roadway that they crashed. The total number of collisions includes instances
where the driver did not respond quickly enough and collided with an approaching
object. Speed exceedance are assigned every time the vehicles speed exceeds the
speed limit, while tickets refers to speed exceedance when the police officer
is watching. The number of stops at traffic lights refers to signals where the
driver either stopped or slowed down enough so that the light changed from red
to green before the driver crossed the limit line. The total run length is the
number of seconds it took the driver to complete the simulation run.
The individual mistakes
will be displayed as follows:
Mistake, Elapsed time from the start of the run, Elapsed distance from the start of the run
The elapsed time is measured in seconds and the elapsed distance is measured in feet.