# Detect contact with a conductive wire [closed]

I have a thin wire, hanging from a hovering quadcopter drone. I'd like to detect physical contact of the wire with a base station. What's an appropriate sensing mechanism for this?

The thin wire does not need to be insulated. It is about 20cm long. We can assume the wire is quite straight and hanging straight down from the drone. The base station is a disk of about 20cm in diameter. The disk is parallel to the ground. The drone will approach the disk from the side in a horizontal motion such that the write hanging below it will contact the edge of the disk. When this happens, I'd like the base station to detect that contact has been made. The drone and the attached wire are not grounded. Hope this is a bit clearer of what I'm trying to do.

• Capacitance.... Oct 2, 2023 at 1:41
• Share details, or do you expect us to guess everything? Oct 2, 2023 at 7:21
• You really need to add a lot more details to allow a reasonable answer. How long is the wire? It is grounded? Is it point contact (end of wire) or laying flat? If there any signal on the wire? Oct 2, 2023 at 12:34
• It would be much easier if the wire was uninsulated at least where it makes contact with the base station. Is there a reason why it needs to be insulated? Which device needs to know whether contact is made? The quadcopter or the base station? If it is acceptable for the base station to make the determination, then the wire need not have an electrical connection with the quadcopter. Oct 2, 2023 at 13:09
• Sorry guys, I've added a bit more detail in the description.
– flux
Oct 3, 2023 at 11:45

One approach that you might be able to get to work is this. You use your base station disk as a monopole antenna. When the copper wire comes into contact with the station disk, they together will create an antenna with a different resonant frequency. You could either

1. feed the base disk with a signal below its resonant frequency, and measure the change in impedance when the quadcopter wire comes into contact with the base disk

or

1. use the base disk as a resonator for an oscillator. When the quadcopter wire comes into contact with the base disk, the resonator frequency will change, and you can measure the change in frequency.

Because the dimensions of your system are small, you will be working at high frequencies. My guess is that option 2 will be harder to implement. That is, I believe creating a variable frequency oscillator using the base disc as a resonator will be more difficult to implement than using a fixed frequency oscillator, and observing the change in the impedance of the antenna. But I could be wrong about this.

• That makes total sense to me. And I agree, option 1 is probably easier. Thank you!
– flux
Oct 4, 2023 at 2:40