Where does deadbeat collide?

In horology the deadbeat (or dead-beat) escapement is a clock escapement, associated with George Graham around 1715, whose locking faces are arcs concentric with the escape wheel's axis. Because of that geometry the escape wheel stays motionless ('dead') while the pendulum finishes its swing, instead of being driven briefly backward as it is in the earlier recoil (anchor) escapement. Removing that recoil disturbs the pendulum less and makes the clock keep better time, which is why the deadbeat became standard in precision regulators. Headrick's Origin and evolution of the anchor clock escapement traces the mechanics of this change. The referent is a physical gear-and-pallet mechanism, unrelated to a control system's step response beyond the shared meaning of leaving nothing moving afterward.[1]

Unit

A recoil-free clock escapement

Recovery means

Not applicable

Measured by

Judged by the absence of escape-wheel recoil and by the rate stability it gives a regulator

In control engineering a deadbeat response is the behaviour of a (usually digital) control system designed so that, after a step change in its input, the output reaches the desired final value in the smallest possible number of sampling intervals and then stays there: zero steady-state error, no overshoot, and no lingering oscillation. A deadbeat controller is the compensator that produces this finite-settling-time response. Ogata's Modern control engineering presents the design of such controllers for discrete-time systems. The referent is a specification on a system's transient response, which shares only the word 'deadbeat' with Graham's clock escapement.[2]

Unit

Settling time, in sampling periods, of a step response with no overshoot

Recovery means

Not applicable

Measured by

Characterised by finite settling time, zero steady-state error and no overshoot in the step response