jensandClaude Sonnet 4.6
40d57dc68a
Both TODO.md backlogs and the README's architecture section still described the Kalman-filter/heat-diffusion design that's since been replaced by the delay-line Pot model and Kalman-free Smith predictor. Check off the items that rewrite already fixed (heat-loss units, transport delay vs. single-pole lag, three-Kalman-tuning), note how the kn/sensor-noise item was resolved differently than proposed, and add newly-spotted issues: brewpi.py wiring set_model_power unconditionally (breaks pid_type "Normal"), kalman.py being dead code in production, stale Kalman/kn keys in the config templates, and debug print()s left in Pot.process(). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
70 lines
3.8 KiB
Markdown
70 lines
3.8 KiB
Markdown
# components/pid design backlog
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Findings from a design review, refreshed against the current state of
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`master` after the Kalman-filter removal and Smith-predictor rewrite (see
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git history for `temp_controller.py`/`temp_controller_smith.py`).
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- [x] **FSM thresholds aren't configurable.** Moved into an optional
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`TempCtrl.Thresholds` config section (`HoldIdle`, `HoldHeat`,
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`IdleHeat`, `IdleHold`, `HeatHold`, `HeatIdle`), merged over
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`DEFAULT_THRESHOLDS` (now in `temp_controller_base.py`, formerly
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`tc_constants.py`) so existing configs without the section keep
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working unchanged.
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- [x] **matplotlib imported at module level in production code.**
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`temp_controller.py`, `temp_controller_smith.py`, and `kalman.py`
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used to `from matplotlib.pyplot import ...` just to support their
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`__main__` self-test plots. The plotting demos (and `kalman_eval.py`)
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moved to `scripts/demos/pid/demo_*.py`; production modules no longer
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import matplotlib.
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- [x] **Three Kalman filters share one tuning.** No longer applicable:
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`temp_controller_smith.py` was rewritten to drop Kalman filtering
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entirely (see below), so there's no shared tuning to split anymore.
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- [ ] **`Pid.scale()` is a gain-scheduling hack, not anti-windup.**
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`pid.py`'s `scale(k)` multiplies every gain by `1/heatrate_soll_set`
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(called from `temp_controller*.py`'s `process()`), but it's framed
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as overshoot compensation, conflated with the real anti-windup logic
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a few lines below. `self.k` also never resets in `reset()`, so a
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stale scale factor can survive a state-transition reset. Consider
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moving this scheduling logic out of the generic `Pid` class and into
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the temp controller, and resetting `k` in `reset()`. Still present.
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- [ ] **No automated tests.** `tests/components/pid/` was added once
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(stdlib `unittest`, no pytest) covering FSM transitions, anti-windup
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clamping, and Kalman convergence, but was removed again before the
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Kalman-filter removal/Smith rewrite, so none of the current
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`temp_controller*.py` behavior (backward-difference + low-pass
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filtered heat rate, the two-model Smith correction) has test
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coverage. This drives a physical heater — worth re-adding.
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- [ ] **`set_model_power` isn't defined on every controller, but
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`brewpi.py` wires it unconditionally.** `brewpi.py` always does
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`heater.set_on_changed("power_set", tc.set_model_power)` regardless
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of `Controller.pid_type`. Only `temp_controller_smith.py` (the Smith
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predictor) defines `set_model_power`; `temp_controller.py` (`"Normal"`)
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does not, so starting the server with `"pid_type": "Normal"` crashes
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at wiring time with `AttributeError: 'TempController' object has no
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attribute 'set_model_power'`. Either add a no-op `set_model_power` to
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`TempControllerBase`, or only wire it when the configured controller
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actually exposes a model to feed.
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- [ ] **Config access is unchecked `dict[key]` everywhere.**
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`params['Hold']`, `model_params['gain']`, etc., throughout, with no
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schema validation at load time. We already hit this bug class once
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(`config.json.sim`'s `gain`/`Model` nesting mismatch). A small
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schema/dataclass validation layer at config-load would surface
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errors immediately instead of mid-`__init__` — and would have caught
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the dead `TempCtrl.Kalman` / `Model.kn` / `Plant.kn` keys still
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sitting in `config.json.templ` and `config.json.sim` (harmless today
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since extra keys are just ignored, but nothing reads them anymore
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after the Kalman/`kn` removal — see `components/plant/TODO.md`).
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- [ ] **`kalman.py` is now dead code in production.** Neither
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`temp_controller.py` nor `temp_controller_smith.py` uses `Kalman`
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anymore; the only remaining references are
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`scripts/demos/pid/demo_kalman.py` and `demo_kalman_eval.py`. Decide
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whether to keep it as a documented standalone filtering example or
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delete it along with the demos.
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