Control loop rate
also: sample rate · loop frequency · sampling period
How often a digital controller reads sensors and updates its output; it must be fast relative to the dynamics or performance and stability suffer.
A digital controller works in discrete steps: sample, compute, output, wait. The interval between steps adds delay to the loop. Too slow and the loop reacts late, overshoots or oscillates; far faster than needed and it burns processor time and power for nothing.
The Nyquist–Shannon sampling theorem says a signal must be sampled at more than twice its highest frequency to be captured at all. That is a floor for measurement, not a target for control: practical loops run many times faster than the response speed they are trying to achieve. Slow thermal processes can be sampled slowly; motor current loops need very fast, tightly timed updates.
Jitter (variation in the interval) and the delay between sampling and output matter as much as the nominal rate. Hardware timers, interrupt-driven sampling and an RTOS with well-chosen priorities are the usual ways to keep timing consistent.
Founder takeaway
Ask what loop rates were chosen and why, and whether timing jitter was measured on the real firmware under full load.
engineer review pending