Detecting Axles using a Teensy 4.1

[jimmie]

I would appreciate advice on creating an axle sensor using a Teensy 4.1 connected to a sensor.

Basically, I need to detect when a wheel of a vehicle rolls over a thin/narrow aluminum strip which is glued to the roadway and placed perpendicular to the direction of traffic. The system needs to detect when a wheel rolls over the strip. Wheels may roll over the strip every 100 ms.

I thought of a simple Piezo sensor but the ones I found would be easily destroyed by the wheels. I also tried the Adafruit 9-DOF Orientation IMU sensor but I could not get it to work.

What is the right sensor to use and a good circuit to connect to the Teensy?

Thanks in advance.

[el_supremo]

You could try something like the sensor strips that cities put on roads to measure the volume of traffic. I presume what they do is the weight of the wheel momentarily closes a circuit consisting of two wires in what amounts to a rubber hose. If that can be done it's a simple matter of hooking it up to a digital pin and "the rest is just software" (tm)

Pete

[jimmie]

Thank you. Yes, those are called axle sensors. They are expensive and require embedding in the asphalt.

I need something simpler ….

[BriComp]

The systems used in the UK for temporary speed measurement consist of a rubber tube with one end (the far end) closed and I assume a pressure sensor on the sensing end measuring pressure pulses. Each positive pulse is a wheel travelling over the sensor.

[jimmie]

The systems used in the UK for temporary speed measurement consist of a rubber tube with one end (the far end) closed and I assume a pressure sensor on the sensing end measuring pressure pulses. Each positive pulse is a wheel travelling over the sensor.

Thank you @BriComp.

Yes, we sue that in the US too but it is bulky, cumbersome and is only for a temporary installation.

[sbfreddie]

Jimmie:
Why not use a small laser and a sensor at the other end?
or,
You could try two thin strips of aluminum foil very close to each other on a non conductive layer perhaps made of Capton or something like it. You could use perhaps a capacitive touch circuit, or a resistive touch circuit to detect the pulses.

Regards,
Ed