To stabilize servo, some form of stroke feedback is required : Either directly to the servovalve, or via a potmeter or a nonlinear stroke observer to the servoamplifier.

He invented the 'monkey fist' — a knot which gives weight to a heaving line; the union plate he called a 'monkey face' and, in times of merrymaking, he frequently 'bled the monkey' to get his grog.

avocado:

So you see, imagination needs ”moodling”— long, inefficient, happy idling, dawdling and puttering.