4.12 Closed-loop control, PID

Outcome 12 of 12 in domain 4 · Digital and microcontrollers

Hold a quantity in a digital closed loop: speed, temperature, current.

My targets

I declare:

Explain the control loop: setpoint, measurement, error, command, and what each PID term does to the error.
Control a motor’s speed with P alone, see the residual error, add I, see the overshoot, add D.
Tune a PID by a known method (Ziegler-Nichols or reasoned trial) and measure response time and overshoot.
Handle the traps: command saturation and integral windup (anti-windup), noise on D, sampling period.
Hold a temperature (iron, bath, enclosure) and a charging current with PID, and say what changes between the two (slowness, delay).
Recognize the PID loop in a commercial motor controller, charger and MPPT regulator.
Diagnosis: a control loop that oscillates or crawls, gain too high, measurement delay or period too long; the trace that shows it.