Bandwidth must be measured on the real joint
Joint bandwidth is constrained by compliance, encoder placement, and the move profile that matters in production. Bench-only figures mislead the quoting phase.
We separate target bandwidth into command-following, disturbance rejection, and recovery after payload swing so controls and mechanics can tune against the same brief.
- Validate with the actual harness and mounting stack, not a shortened test rig.
- Track position error under disturbance, not only under command input.
- Record gain windows that remain stable across temperature spread.
Joint tuning windows
Use one worksheet for controls, mechanics, and production FAT.
| Window | Goal | Failure sign |
|---|---|---|
| Command following | < 5% overshoot | Oscillation on short point-to-point moves. |
| Disturbance rejection | < 0.8 deg drift | Payload bump causes visible lag. |
| Thermal drift | Stable after 20 min | Retune required after warm-up. |
Loop-check pseudocode
const stable = overshoot < 0.05 && settlingMs < 80 && disturbanceDriftDeg < 0.8;
return stable ? 'ready-for-fat' : 'retune-with-payload';Continue Reading
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