System identification

Physics gives you the shape of a model; system identification fills in the numbers from experiments. Typical tests apply steps, frequency sweeps or pseudo-random signals to an actuator, record the response, and fit a model: a time constant and delay, a transfer function, or a state-space model.

A good identified model pays off repeatedly. It lets you tune controllers in simulation, run hardware-in-the-loop tests, size actuators, and predict how a change (a bigger motor, a different fan) will behave. It also gives a baseline for spotting when units in the field start to behave differently.

Where it bites: test signals must excite the behavior you care about without damaging anything, and a model identified at one operating point may not hold at others. Plan tests across temperature, load and supply voltage.