Make grain_mass/water_mass per-step and re-derive plant params on change

grain_mass and water_mass now live on each step (defaulted from
default.step) instead of being fixed for the whole brew, since both
change over a mash (malt going in, water boiling off).
Sud.derive_plant_params() takes them as arguments so it can be
recomputed per step; the demo re-applies the resulting M/C to both the
real plant and the controller's Smith-predictor model on every step
change via the new Pot.set_thermal_params()/
TempController.set_model_params().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CgR9tPaSzFkAwRAUyeaaCD
This commit is contained in:
2026-06-20 07:45:42 +02:00
co-authored by Claude Sonnet 4.6
parent ca0a014ffb
commit 241a796ffa
6 changed files with 41 additions and 16 deletions
+11 -4
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@@ -129,10 +129,7 @@ environment (`$WORKON_HOME`/`$BREWPI_HOME`) on a Raspberry Pi-style deployment.
## Mash schedules
Files under `sude/` describe a brew's mash schedule ("Sud"): `pot_mass`,
`pot_material`, `grain_mass`, `water_mass` (used by `Sud.derive_plant_params()`
to compute a lumped thermal mass/specific-heat pair for `Pot`'s `M`/`C`, e.g.
in `scripts/demos/sud/demo_sud.py`, instead of hand-tuning them), and a
`steps` list, each either:
`pot_material` (fixed for the whole brew), and a `steps` list, each either:
- a ramp — `"ramp": {"rate": ..., "temp": ...}` — ramp to `temp` at `rate`
(°C/min), or
@@ -147,6 +144,16 @@ Both `ramp` and `hold` carry a `stirrer` block (`speed`, `interval_time`,
the user with) to pause for confirmation once the step completes, e.g. to
add malt or check gravity, instead of advancing immediately.
Each step also has its own `grain_mass`/`water_mass` (defaulted like
everything else from `default.step`), since both change over the course of
a brew — e.g. malt going in partway through, or water boiling off. Pass a
step's `grain_mass`/`water_mass` to `Sud.derive_plant_params()` (together
with the brew-wide `pot_mass`/`pot_material`) to get that step's lumped
`Pot` `M`/`C`; `scripts/demos/sud/demo_sud.py` recomputes and re-applies
these (via `Pot.set_thermal_params()`/`TempController.set_model_params()`,
on both the real plant and the controller's Smith-predictor model) every
time the current step changes, instead of deriving them once at startup.
The top-level `default.step` object gives every field above (including the
nested `ramp`/`hold`/`stirrer` blocks) a default value; a step in `steps`
only needs to specify the fields it overrides — anything it omits is filled
+4
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@@ -24,6 +24,10 @@ class TempController(TempControllerBase):
self.model.set_power(power)
self.model_delay.set_power(power)
def set_model_params(self, M, C):
self.model.set_thermal_params(M, C)
self.model_delay.set_thermal_params(M, C)
def on_state_entered(self, state):
if state == States.HEAT:
self.model.initial(self.theta_ist)
+4
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@@ -56,6 +56,10 @@ class Pot(APlant):
def set_ambient_temperature(self, theta_amb):
self.theta_amb = theta_amb
def set_thermal_params(self, M, C):
self.M = M
self.C = C
def set_power(self, power):
self.p_in = power
+10 -9
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@@ -37,7 +37,7 @@ def _build_step(number, defaults, raw_step):
ramp or a hold depending on which of those keys it specifies; the other
is left out rather than synthesized from defaults."""
step = {'number': number}
for key in ('descr', 'user_message', 'user_wait_for_continue'):
for key in ('descr', 'user_message', 'user_wait_for_continue', 'grain_mass', 'water_mass'):
step[key] = raw_step.get(key, defaults.get(key))
for key in ('ramp', 'hold'):
if key in raw_step:
@@ -59,8 +59,6 @@ class Sud(AttributeChange):
self.pot_mass = data.get('pot_mass', 0)
self.pot_material = data.get('pot_material')
self.grain_mass = data.get('grain_mass', 0)
self.water_mass = data.get('water_mass', 0)
self.index = -1
self.hold_remaining = 0.0
@@ -68,13 +66,16 @@ class Sud(AttributeChange):
self.step = None
self.user_message = None
def derive_plant_params(self):
"""Lumped (mass, specific heat) lifted from pot_mass/pot_material/
grain_mass/water_mass, for use as Pot's "M"/"C" params."""
def derive_plant_params(self, grain_mass, water_mass):
"""Lumped (mass, specific heat) lifted from pot_mass/pot_material and
the current step's grain_mass/water_mass, for use as Pot's "M"/"C"
params. grain_mass/water_mass vary per step (e.g. malt going in,
water boiling off), so this is recomputed on every step change
rather than once at startup."""
c_pot = SPECIFIC_HEAT_BY_MATERIAL.get(self.pot_material, SPECIFIC_HEAT_WATER)
mass = self.water_mass + self.grain_mass + self.pot_mass
capacitance = (self.water_mass * SPECIFIC_HEAT_WATER
+ self.grain_mass * SPECIFIC_HEAT_GRAIN
mass = water_mass + grain_mass + self.pot_mass
capacitance = (water_mass * SPECIFIC_HEAT_WATER
+ grain_mass * SPECIFIC_HEAT_GRAIN
+ self.pot_mass * c_pot)
return {
+8 -1
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@@ -35,8 +35,9 @@ if __name__ == '__main__':
sud = Sud("sude/sud_0010.json")
first_step = sud.schedule[0]
plant_params = {
**sud.derive_plant_params(),
**sud.derive_plant_params(first_step['grain_mass'], first_step['water_mass']),
"L" : 0.2,
"Td" : 60
}
@@ -65,9 +66,15 @@ if __name__ == '__main__':
stirrer.set_duty_cycle(1.0 if speed > 0 else 0.0)
stirrer.set_speed(speed)
def apply_plant_params(step):
params = sud.derive_plant_params(step['grain_mass'], step['water_mass'])
plant.set_thermal_params(params['M'], params['C'])
ctrl.set_model_params(params['M'], params['C'])
def on_step_changed(step):
if step is not None:
print(f"Step {step['number']}: {step['descr']}")
apply_plant_params(step)
if 'ramp' in step:
ctrl.set_theta_soll(step['ramp']['temp'])
ctrl.set_heatrate_soll(step['ramp']['rate'])
+4 -2
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@@ -3,14 +3,14 @@
"Description" : "Rotfraenkisch, Dunkles Lager",
"pot_mass" : 5.960,
"pot_material" : "Edelstahl 18/10",
"grain_mass" : 5.21,
"water_mass" : 22,
"default":
{
"step" : {
"descr": "Put description here",
"user_message": "Put user message here",
"user_wait_for_continue": false,
"grain_mass" : 5.21,
"water_mass" : 22,
"ramp": {
"rate": 1.0,
"temp": 0,
@@ -33,6 +33,7 @@
"steps":
[
{
"grain_mass" : 0,
"descr": "Heizen für Einmaischen",
"ramp": {
"rate": 1.8,
@@ -101,6 +102,7 @@
}
},
{
"water_mass" : 21,
"descr": "Halten Abmaischen",
"user_message": "Quittieren zum Abmaischen",
"user_wait_for_continue": true,