Ultrasonic Sensor as Start/Stop signal

Using Arduino Sensors
#1

I want to use this Ultrasonic Sensor THIS to create a LapTimer for my RC Car.

I tried several things with IR LEDs, but this requires a setting on both sides of the track, I don't want that.

So my idea is to have the above sensor, and let it check if something passes. If so, start the timer, if again, stop it. I have the code for that, but will the sensor detect it fast enough?

Little math:

  • approx. speed: 20 km/h -> 5,5 m/s
  • assumed "detection range" 1m (the wider the car is away the bigger it gets obviously as it has a 15 degrees angle)
  • the car will be in that range for approx 0,25s

Is that enough time for the sensor to detect a difference.

Speed could be lowered a little I guess, so maximum could be 0,5s.

If that is not suitable for such a project, any other ideas that do not involve having sensors on the other side of the track?

Any hint highly appreciated.

Cheers

PrimuS

#2

What about retro reflective sensors?

Weedpharma

#3

While that looks quite interesting, I think it may be a little "over the top" and from what I understand it still needs something to reflect on the other side of the Track?

Anything about the speed issue?

Cheers

#4

These detectors use the reflected light to change state. It will change when the car goes past if it is within range.

Weedpharma

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#5