STISIM Drive
(SDL) - V - Vehicle
Display a vehicle in the
driver’s lane, traveling the same direction as the driver. If the driver’s
vehicle comes in contact with the this new vehicle, the crash sound effect will
be played (if active), and a collision will be added to the driver’s collision
total. Because of memory limitations, the V event is limited to a total of 550
occurrences in the entire scenario. Vehicles that are displayed using the V
event have some intelligence built into them. If they are approaching the
driver from behind, or approaching a stop sign or traffic signal light, they
will attempt to do the right thing. When dealing with traffic lights, if the
light changes from green, and they are capable of stopping without breaking the
laws of physics, the vehicle will stop at the light. When the light changes to
green, the vehicles will then accelerate back up to their specified speed. The
same action will take place at stop signs. When in traffic, a vehicle that is
approaching the driver from behind and in the driver’s lane, will try to slow
down so that it does not collide with the driver’s vehicle. If a driver were to
swerve in front of an approaching vehicle, the approaching vehicle will try to
slow down, but it may not be enough to avoid a collision. Unfortunately, the
vehicles are still "dumb" with respect to each other, and they do not
know, or care where any of the other vehicles are located.
EVENT PARAMETERS:
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PARAMETER 1: |
The speed, in feet/second,
of the new vehicle. You may also reference the vehicle’s speed with respect
to the driver’s speed by using a * or / in front of this parameter. If a *
symbol appears as the first character in the parameter specification, the
program will take the value of parameter 1 and add it to the current speed of
the driver’s vehicle and use this as the new vehicle speed. This speed will
remain constant, based on the driver’s speed when the event begins. If a / symbol appears as the first character in the parameter specification, the program will take the value of parameter 1 and add it to the current speed of the driver’s vehicle at each time step. This means that the new vehicle speed will be changing as the driver’s speed changes. Therefore, if the driver’s vehicle slows down, the new vehicle will slow down accordingly. |
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PARAMETER 2: |
The longitudinal distance, in feet, that the vehicle is away from the driver when the vehicle initially appears. |
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PARAMETER 3: |
The lateral lane position,
in feet, of the center of the vehicle with respect to the roadway’s dividing
line. It is important to remember that if all of the lanes of traffic are in
one direction, the roadway’s dividing line is defined as the left edge of the
roadway. You may also reference
the vehicle’s position with respect to the driver’s position by using a * or
/ in front of this parameter. If a * symbol appears as the first character in
the parameter, the program will take the value of parameter 3 and add it to
the current lateral position of the driver’s vehicle and use this as the
vehicle’s lateral position. If a / symbol appears as the first character in the parameter, the program will take the value of parameter 3 and add it to the current lateral position of the driver’s vehicle at each time step. This new value will be used as the vehicle’s lateral position. This means that the new vehicle’s lateral position will be changing as a function of the driver’s lateral position. Therefore, if the driver goes to the right, the new vehicle will also move to the right. |
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PARAMETER 4: |
If the new vehicle will
be decelerating (set using parameters 6-21), then this tells the simulation
whether or not to use the brake lights on the new vehicle. 0 - Brake lights will
remain the same color |
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PARAMETER 5: |
Vehicle model type number
{Vehicles}. You may assign the vehicle a random
number by using the following syntax notation: *[low range]~[high range]
(for example *1~8) In this case, the program will randomly choose a type number from all of the numbers between the low range number and the high range number. In the example, a number between 1 and 8 (inclusive) would be used. This parameter used to be the vehicle color, but since STISIM Drive uses predefined vehicle models, you must now choose a model instead of a color. |
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PARAMETERS 6-25: |
Parameters 6 through 25 have
been included so that you have more control over how the new vehicles behave.
We have tried to make the vehicle behavior as generic as possible so that a
wide range of scenarios can be programmed. Parameters 6 through 25 are
actually grouped into 5 separate sets of parameters, 6-9, 10-13, 14-17,
18-21, and 22-25. Each of these sets describe a particular action that the
vehicle will take. This allows you to control the vehicle 5 separate ways
after it is initially displayed on the screen. You don’t have to use all 5
actions, any number between 1 and 5 can be used for each vehicle. Each action
that you would like the vehicle to take is controlled by the following
vehicle parameters: Parameters
6,10,14,18,22: Closure time, in seconds,
between the driver’s vehicle and the vehicle you are controlling, this can be
both positive and negative depending on the action that is desired. Positive
meaning that the two vehicles are getting closure to one another, negative
meaning that the vehicle’s are getting farther apart. Specifying the closure
time so that the event acts as you intended is not an easy task. Since the
closure times are irrespective of the locations of the 2 vehicles, you can
add an additional attribute to the closure time parameter that tells STISIM
Drive to only activate the closure time if the event vehicle is in
front of or behind the driver’s vehicle. If the closure time parameter ends
with an F, the action will only be activated when the new vehicle is in front
of the driver’s vehicle and the closure time criteria is met (e.g. 10F would
mean only in front of the driver’s vehicle and within 10 seconds and
closing). Placing a B at the end of the closure time parameter, instructs
STISIM Drive to only take action when the new vehicle is
behind the driver’s vehicle. If neither F or B appears, STISIM Drive
will activate when ever the closure time criteria is met. Parameters
7,11,15,19,23: Lateral distance that the
new vehicle will move, with respect to its current lateral position, in feet.
The vehicle’s current lateral position is always with respect to the
roadway’s dividing line, with positive to the right. Like parameter 3 above,
you may use the * and / symbols at the beginning of the parameter
specification in order to reference the lateral position of the vehicle with
that of the driver’s vehicle. Parameters
8,12,16,20,24: New speed, in
feet/second, that the vehicle will be traveling at the end of the transition
period. Since you will be specifying a transition time, the program will
perform a linear transition from the vehicle’s speed when the transition
begins until it reaches the specified speed at the end of the transition
period. If you specify a speed that is slower than the current vehicle speed,
then the vehicle will decelerate during the transition period. As with
parameter 1 above, you may use the * and / symbols at the beginning of the
parameter specification to reference the new speed to the driver’s vehicle. Parameters:
9,13,17,21,25: The amount of time, in seconds, that the transition will occur over. |
EXAMPLE:
100,V,/30,-250,*0,1,7,
5,/12,*30,2, -5, *0,/30,2
The above event example
illustrates a vehicle approaching the driver’s vehicle from behind, and then
passing the vehicle. First, when the driver’s vehicle has traveled 100 feet down
the road, a vehicle that will travel at a constant 30 ft/sec (/30) faster than
the driver will be displayed 250 feet directly behind the driver (-250,*0).
This means the new vehicle will initially be approaching the driver’s vehicle
from behind, and in the driver’s lane. The brake light flag is set so that if
the vehicle begins to decelerate, the brake lights will turn on (1). The model
type number of the vehicle is specified by the seventh field and this tells the
program to use vehicle model number 7.
The remainder of the
parameters deal with the vehicle taking some type of action. The first 4 action
parameters (5,/12,*30,2) tells the program that when the new vehicle and the
driver’s vehicle are within 5 seconds of each other, move the new vehicle 12
feet to the right of the driver’s vehicle, and set the new velocity so that it
is 30 ft/sec faster than the driver’s current speed. All of this will occur
during the 2 seconds following the initiation of the action.
After the vehicle has
passed the driver and is pulling away, it still needs to return to the driver’s
lane. To do this the second action listed on the event line is used (-5, *0,/30,2).
When the vehicle is 5 seconds in front of the driver’s vehicle (-5), then the
second action will begin. This second action consists of the new vehicle
pulling directly back in front of the driver (*0), traveling at a constant 30
ft/sec faster than the driver (/30) no matter what the driver’s speed is. Like
the first action, this action will occur during the 2 seconds following the
initiation of the action.