Control engineers sometimes ask: “Can I drop GSRF on the measured plant signal that arrives late and use that as a softer command?” The workbench answer is a hard red light for balanced Practical.
Locked delay numbers
MAD to delayed measured plant versus EMA (characterization v4 delay pack):
| Plant delay τ | GSRF vs EMA (MAD-to-measured) |
|---|---|
| 3 minutes | ~+59% worse |
| 6 minutes | ~+97% worse |
| 10 minutes | ~+106% worse |
Full cage: Evidence · Boundaries · narrative: When GSRF lost.
Mechanism (why the spring loses)
GSRF’s spring pulls toward a declared normal \(x^*\) while softly listening to observations. When the “observation” is a delayed truth, the spring still fights for the normal and the delayed measurement fights for where the plant was minutes ago. EMA has no restoring thermostat— it is happier lagging the delayed stream. On this job, lagging is the lesser evil.
What to use instead
- Delayed closed-loop command path: EMA / model-based control / delay-aware designs—not balanced GSRF
- Pre-model sensor hygiene (no delayed command): GSRF mid-band kill + peaks remain on-mission
- Permanent level shifts without delay games: adaptive \(x^*\) (see adaptive note)
Verdict
Do not deploy balanced GSRF as a delayed closed-loop command smoother on the tested timescales. Deploy it to calm signals before models and actuators when delay is not the dominant plant truth path. Publishing this loss is intentional—same trust architecture as red lights on the Evidence page.
Sources: characterization v4 delay · Evidence boundaries · when-gsrf-lost · compare decision table