Hysteresis
A difference in valve position for the same signal depending on which direction it was approached from.
What it means
Hysteresis means the valve ends up in a different place for the same input signal depending on whether that signal was rising or falling. Plot commanded position against actual position and it appears as a loop rather than a line.
In practice hysteresis, deadband and backlash are used loosely and often interchangeably on a plant. The distinctions matter less than the consequence, which is the same in every case: the controller cannot place the valve accurately, and the loop cycles.
Related
Where this comes up
Last reviewed 2026-08-01.