Files
brewpi/components/pid/temp_controller_smith.py
T
jensandClaude Sonnet 4.6 241a796ffa 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
2026-06-20 07:45:42 +02:00

66 lines
2.3 KiB
Python
Executable File

from components.plant.pot import Pot
from components.pid.temp_controller_base import TempControllerBase, States
class TempController(TempControllerBase):
def __init__(self, dt, params, model_params, theta_amb=20):
TempControllerBase.__init__(self, dt, params)
self.dt = dt
self.last_theta_ist = 20
self.heatrate_ist = 0
# Fast model: same plant model but with zero transport delay, used
# to predict the current temperature without the dead time.
self.model = Pot(dt, {**model_params, 'Td': 0}, theta_amb)
# Delayed model: keeps the plant's assumed transport delay, so it
# can be compared like-for-like against the real (delayed) measurement.
self.model_delay = Pot(dt, model_params, theta_amb)
self.theta_ist_plant = 0
self.theta_ist_model = 0
self.theta_ist_model_delay = 0
def set_model_power(self, power):
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)
self.model_delay.initial(self.theta_ist)
def post_pid(self):
self.model.process()
self.model_delay.process()
def process(self):
self.theta_ist_plant = self.theta_ist_set
self.theta_ist_model = self.model.get_temperature()
self.theta_ist_model_delay = self.model_delay.get_temperature()
# Smith predictor: use the fast model's prediction, corrected by the
# mismatch between the real (delayed) plant and the delayed model,
# so the dead time drops out of the feedback path.
self.theta_ist = self.theta_ist_model + (self.theta_ist_plant - self.theta_ist_model_delay)
heatrate = (self.theta_ist - self.last_theta_ist)/self.dt*60
alpha = 0.1
self.heatrate_ist = (1-alpha) * self.heatrate_ist + alpha*heatrate
self.last_theta_ist = self.theta_ist
# Compensate for max heat rate to reduce overshoot
hold_scale = 1.0/self.heatrate_soll_set if self.heatrate_soll_set > 0 else 1.0
self.heatrate_soll = self.heatrate_soll_set * self.pid_hold.get_y()
theta_err = self.theta_soll_set - self.theta_ist
heatrate_err = self.heatrate_soll - self.heatrate_ist
diff = self.theta_soll_set - self.theta_ist
self.process_fsm(diff)
self.process_pid(theta_err, heatrate_err, hold_scale)