Backlash

Backlash is why some precision equipment is so annoying to use. In an electronics lab, I had an apparatus that would measure resistance or luminosity or something like that in a black box, and I had to turn a little crank to make the sensor mount move a specific distance that was measured by an encoder wheel on the crank. I had to take a measurement at specific intervals. If I overshot one part, I had to start all over again because if I backtracked, the resulting backlash would introduce error into my readings.

Backlash should not be confused with a deadband, which basically erases all signal below a specific theshold. Backlash is different because it only occurs when you reverse the input signal.

Back"lash` (?), n. [Back , adv. + lash.] Mech.

The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts, resulting from looseness in fitting or from wear; also, the jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.

© Webster 1913.