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How would I make a sensor sense motion coming at me from behind while I'm moving forward? Answered

I'm trying to make a small sensor that would detect a large object coming at me from behind at about 60mph while I'm moving forward at around 7mph. What kind of sensor would I use?
I looked up the different types and I found Passive/active infrared, optic-based, piezoelectric, and ultrasonic. I tried to figure it out myself and my best guess is ultrasonic? Like what cars use to detect deer, they use "ultrasonic airflow sensors".

Ideally the sensor would beep and get louder or faster as the object approaches. Would I use an arduino?
I'm very new at this :/
Thanks for any help!

Tags:motion sensorsensorultrasonicairflowinfraredoptic

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Toga_Dan
Toga_Dan

4 years ago

1. I like the concept. It has potential for bikers or pedestrians.

2. Oldschool option: rearview mirror or listening attentively.

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Downunder35m
Downunder35m

Reply 4 years ago

Mirror??
How much power does it need? ;)

Actually thought about something similar a while ago for the massive traffic at our boat ramps during peak season.
Not really for four wheel but I will keep watching in the hope to find really good ideas converted into something working :)

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arrowstation
arrowstation

4 years ago

Thanks lol.

What I want to do is make something that warns me that a car is behind me while I'm listening to music. It would beep or turn the music down or something. I always want to listen to music while biking but I'm too scared especially on the back country roads.

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Downunder35m
Downunder35m

4 years ago

Ultrasonics will give you around 15m of detecting range unless you go really high quality and know how to write your own code for it.
Infrared can work at greater distances but is usually limited to around 5m for good detections - again better sensors go a little bit further.
Piezo I don't think will work properly unless used for ultrasonic application.
IMHO a pulsed laser diode would be best.
Due to the speed you need something to detect before the distance is too short as the processing takes time as well and you need a distance reading of some sort as well.
Do some reading on how to use your sensors of choice for distance measurements and check the datasheets for the max distance possible.
After that it is just a matter of digging in the Arduino code libraries...

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arrowstation
arrowstation

Reply 4 years ago

I think I'll test out the concept first with ultrasonics then try the pulsed laser diodes (which look promising).

Thanks!