What would I use to make an arm that can sense when an additional object has been placed on it?
Here is a link to a lame drawing of what I want to be able to do:
I want to be able to add the orange ring to arm #1 and have it transmit (T) to the receiver (R) that a ring has been added to that particular arm. Then if I add another one (green ring), I want it to transmit that another one had been added.
If I add one to arm #2 I want the signal to transmit that an object has been added to it, but be able to tell which arm the object was added to.
And vice versa, if an object was removed from either arm.
I have thought about using some type of inductor coil to sense the change when something was added. I am not too thrilled about having to use magnetic fields to get the job done though...
I figured that RF signals would work well for the transmitting of data, but am willing to hear any other options.
I am totally uninformed on what types of sensors are out there. Is there one that may work for this type of need? I am willing to look at magnetic/electro-magnetic sensing and any other type of sensing that may be capable to detect incremental changes.
Also, what could I use to differentiate the signals coming from particular arms?
I am a total beginner, go easy on me for being very ignorant <:}