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jensandClaude Sonnet 4.6 c6e9258351 Rename config templates: .templ → -sim.json.tpl, config_real.json → -real.json.tpl
Consistent naming: config-sim.json.tpl and config-real.json.tpl.
Update README and TODO references accordingly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SH2D4LRuCnhLSzoYerAfJX
2026-06-28 20:23:29 +02:00

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# components/plant design backlog
Findings from reviewing `pot.py`'s water-bath model against real-plant
behavior (sim/real control mismatch reported by user), refreshed against
the current `delay`-line rewrite of `Pot`.
- [x] **Heat-loss term has wrong units.** Fixed by the `Pot` rewrite:
`process()` now computes `p_loss = self.L * self.M * (self.temp -
self.theta_amb)` in Watts and applies `self.temp += (self.delay.get()
- p_loss) / (self.M * self.C) * self.dt` — the same `/(M*C)`
normalization for both the gain and loss terms, instead of the old
mismatched `leak = 1/self.M * self.L * (...)/ self.theta_amb`.
- [x] **Thermal lag modeled as single-pole lag, not transport delay.**
Fixed: `Pot` no longer uses `HeatDiffusion`'s `alpha=dt/Td`
exponential smoothing (that module was deleted). It now delays the
input power through `plant/delay.py`'s `Delay` (true dead time)
before integrating it, matching what this item recommended.
- [x] **`kn` is loaded but never applied.** Resolved differently than
originally proposed: `kn` was removed from `Pot` entirely rather than
wired up as plant-side measurement noise. Sensor noise is now
modeled one layer up, in `TempSensorSim` (`temp_offset`/`variance`,
wired from `brewpi.py`'s `TempSensorFactory.create(..., temp_offset=
-0.15, variance=0.01)`), not in the plant model. The stale
`Model.kn`/`Plant.kn` keys this item flagged have since been deleted
from `config-sim.json.tpl`/`config.json.sim` too.
- [x] **`theta_amb` is hardcoded, not configured.** Fixed: added a
top-level `ambient_temperature` key to `config.json`(`.templ`/`.sim`);
`brewpi.py` reads it once and passes it to both the real `Pot` and
(via a new `theta_amb` param) `temp_controller_smith.py`'s internal
models, so the Smith predictor's model matches the real plant's
assumed ambient instead of silently defaulting to 20. `Pot` also
dropped its separate `params['theta']` initial-temperature field —
it now always starts at `theta_amb` (so the same config value governs
both the assumed ambient *and* the pot's starting temperature; there's
no longer a way to start a sim at a temperature other than ambient).
Real ambient temperature still isn't modeled as a *drifting*
disturbance (it's a static config value, not a live sensor reading,
though `Pot.set_ambient_temperature()` now exists as a hook for that),
so robustness to ambient drift remains untested.
- [ ] **No actuator/process realism.** Partially improved (`process()`
clamps `self.temp` to `min(100, ...)`, won't simulate past boiling)
and partially regressed: `Pot` also dropped its `gain` (heater
efficiency) factor entirely — `process()` now applies 100% of
commanded power with no loss, whereas before `params['gain']` could
model e.g. an 80% efficient transfer. `Model.gain`/`Plant.gain` were
dead keys in `config.json.sim` (already absent from `.templ`) before
that file was removed entirely — see `components/pid/TODO.md`'s
config-validation item. Still no
heater power saturation enforced inside `Pot` itself (handled ad hoc
in demo harnesses), no evaporation/lid heat loss, and no varying
thermal mass `M` as volume changes (e.g. boil-off, adding
water/grain) — `M` is a fixed constant for the whole simulation.
- [x] **Debug `print()`s left in `Pot.process()`.** Fixed: the
unconditional `p_loss`/`theta_amb`/`temp` prints (leftover from the
heat-loss-units fix) were removed.