Basically, the mentor believes that there is an external use for a rotary encoder than reading the rotations of an axle. His idea is that we have a mechanism that pivots like a scale and somehow you should be able to read the partial revolutions along this scale like contraption by attaching it near the center part of the contraption. I don’t have much information on how exactly it works but it is my belief that it only works through attaching it to an axle directly, but we as a team are not completely sure.
So, is it possible to attach a rotary encoder near the center rotating point of a scale and measure the partial rotation of the scale?
If you have a rotary shaft, you can measure partial rotations.
The KOP encoders (US Digital) have either 250 or 360 (depending on the year) lines per revolution. You can decode each line as 4 pulses, for a grand total of 1000 or 1440 counts (definite positions) per rotation.
An analog potentiometer is much much better for limited position control, as it is not an incremental sensor like an encoder, but rather an absolute sensor. This means that, when you boot up, you know exactly where you are, without another sensor to reset the position. Some companies also make absolute magnetic sensors, which read the absolute angle of a shaft magnetically with no mechanical limits. There used to be one of such a sensor in the KOP, now they’re in FIRST Choice.