Knowledge Base

Article Number: 37 | VC3 | VC4 | Post Date: June 1, 2017 | Last Updated: June 1, 2017

How can I simulate a vehicle coming to a complete stop before accelerating and turning a few seconds later? 

Stopping and resuming vehicle motion can be accomplished in Virtual CRASH by tuning the time parameter for the acceleration sequence. In the example below, the red vehicle moves into the left turn lane, while decelerating to rest. It stops at the end of the turn lane. Here the auto-driver system is used to control the steering for both vehicles. The blue vehicle approaches in the eastbound lane, momentarily preventing the red vehicle from turning. The vehicle positions are shown in 1 second increments below. 

Here we zoom into the intersection. 

To help fine-tune the timing of our left turn, we’ll use the Diagram tool. The Diagram tool can be accessed by going to Window > Diagram. 

With our red vehicle selected in the Diagram tool (BMW – X 5.3), we can visualize the velocity versus time graph. This graph shows (1) the red vehicle driving at a constant speed, (2) then decelerating, (3) then traveling again at a lower constant speed, (4) and finally decelerating again to rest (yellow circle). 

Next, another sequence needs to be placed into the sequences menu. Simply press “add sequence”. 

Change the new sequence entry’s type to “acceleration”. The time is set to 5 seconds as a first guess, and a reasonable acceleration rate of 4 ft/s^2 is used. Remember, the “time” parameter determines the time delay in starting the selected sequence with respect to the start of the prior sequence. In this case, the acceleration event will not begin until 5 seconds after the prior deceleration event began. By using the Diagram tool, we can immediately see a visual representation of our timing choice.  

Finally, we can review our simulation, and fine-tune the acceleration sequence entry time parameter to achieve the necessary delay to allow the blue car to clear the intersection before the red car resumes the left turn. In this case, using a time value of 7 seconds implies the red car remains at rest for about 5.5 seconds before resuming the turn. 

Tags: how to pause a vehicle, stop and go, sequences, sequence, delay vehicle, left turn, time.

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