Sensing where a thin metal sheet is

Hi guys!

I am a mechanical engineering student. I have a small stepper motor which controls a metallic "flag shaped" shutter with dimensions of 14x10x1 mm. I want to find the best possible solution for measuring where the shutter is. I have a vague memory of a way to measure how far a thin metal sheet was inserted in a column, but I cannot find it! If anyone has any input or nice solutions I would be glad to hear them! I have thought about ways with photosensors, but they feel very prone to disturbances from the surroundings.

Thanks in advance!


Steppers are good for precise positioning. If you know where the stepper starts (home) then each step will move a precise amount. Use a photo sensor to home the stepper and from there count steps to know where the shutter is. Photo sensors can be very reliable if used properly. The most important thing is to shield the sensor from ambient light.

Thanks for the response!

Yeah, it is absolutely leaning towards photosensors.

The thing is that I am to solve a problem where the operators are mounting the hardware and need a foolproof way of testing this. They sometimes accidentally bend a pin or two in the connector so the spools aren't activated properly, which renders an unpredictable result. Sometimes the flag is also mounted wrongly, which is why I would like to detect how far the flag went.

I might have a better idea if I could see a picture of the device and the internal workings.

Wow! You are really quick! :slight_smile:

I am also thinking of somehow measuring the resistance through the flag since it is metal. Much how a slider pot works.

I don’t have the access to the internal workings, but the device looks like the picture. (Pen for scale)

So the problem I am solving is that sometimes the flag is not mounted properly, the pins are bent or something else like that which makes the component not move from A to B as it should. I need to detect that the movement isn’t the one from A to B and basically just output a pass or fail.

Thanks for the help, really appreciate it!