====== Limit Switch ======

Limit switches are used to detect when some mechanism has hit some form of limit. For instance, a limit switch would be used to detect when an elevator is at its lower limit or when an arm is at its maximum angle.
To [[Designing for Control|design for controllability]], every mechanism that has a limit should have a limit switch on it. Ideally, there should be at least one limit switch and a [[Quadrature Encoder]].

Most limit switches are mechanical, using the physical movement of a switch to short an electrical circuit which is then detected by the robot controller. One kind is the [[https://en.wikipedia.org/wiki/Miniature_snap-action_switch|Snap Action Switch]]


Other limit switches use the Hall Effect. These consist of two components. First is the magnet, which typically sits on the moving mechanism. The second is the [[https://en.wikipedia.org/wiki/Hall_effect_sensor|Hall Effect Sensor]], which will stay on the static part of the mechanism. Internally, the Hall Effect Limit Switch will convert the analog Hall Effect into a digital output that behaves similarly to a mechanical limit switch.