What is the definition of a limit switch for a robot?
a limit switch is usually either electromechanical or opto-electronic in nature. The switch will be activated when a mechanical motion (for instance, of a robot arm or X-Y table) reaches a certain physical position. This position is usually chosen based on some mechanical constraints (for instance, the lead screw of an X-Y table may jam if one of the axes is moved too far in a particular direction). In any event actuation of the switch usually involves phycial contact between the moving part and the (rigid) switch, or in the case of a photomicrosensor, a mechanical interruption of the light bean occurs. A controller detects the actuation of the switch and will halt any further motion in that direction, hence “limiting” the motion.
