I like this idea if it is easier to developIf using a stepper motor with timing pulleys, the position can be controlled and repeated rather accurately by simply driving the stepper a certain number of steps. So you may not need a number of position sensors.
and this sounds good to me though I have no knowledge in this areaThe main issue would be if the stepper would miss some steps along the way. That can be handled by having a rotary optical encoder attached to the stepper to verify that the stepper is actually turning the number of steps it is told to turn. You can have a homing switch/sensor at one end of travel and use a rotary encoder that has a 0 degree position sensor on it. I think that combination would give an accurate start position.
By hards top do you mean some kind of physical resistance that stops the carriage travelling? not sure what I understand here?Or, the simplest homing method is to drive the motor against a hard stop.
OKYou could certainly have some position sensors along the way as an extra check.
Well I was thinking of perhapsAnd, how long are you thinking for the neck/fret board ?