Files
ashvale-station/ashvale/estimation.py
T
kemal e27a4b41c8 Outlook to Live, humidity calibration, Models tab rebuilt without scrollers
Seven day outlook moves from History to Live, which now runs four rows.
Conditions ahead tightened so the Live column no longer needs a scroller.

Adds HumidityCompensator: an additive RH offset estimated by one-step RLS from
a trusted hygrometer, clamped to +/-35%, persisted, exposed at
POST /api/calibrate/humidity and on the renamed Models and calibration tab.

It also implements the psychrometric term (RH moved from element temperature
onto air temperature via conserved vapour pressure) but leaves it OFF by
default. The thermal argument predicts a hot element reads low; measured
against a reference hygrometer this board read 75.4% where the truth was
50.4%, so it reads HIGH and that correction would push it the wrong way. When
the flag is enabled, simulate.py applies the exact inverse, per the
simulator/compensator trap in DESIGN.md section 2.

Models pane rebuilt: the scorecard is one column per target so all 18 heads
are visible, and no panel on the tab uses an internal scroller. Verified in
Chromium at 1600x900: Live, History and Models all report zero scrollbars,
zero clipping, no page scroll, zero console errors. Backtest is numerically
identical to the previous commit, confirming the humidity work is a no-op
while the flag is off.
2026-08-15 21:36:10 +01:00

326 lines
13 KiB
Python

# Copyright 2026 Kemal Yaylali
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""State estimation: the layer between a noisy sensor and an honest number.
Two jobs here, both familiar from soft-sensor work:
1. `ThermalCompensator` removes the SoC self-heating bias. The classic
Sense HAT correction `T = T_sensor - k (T_cpu - T_sensor)` is a
one-parameter grey-box model. We keep the structure and estimate `k`
recursively whenever a trusted reference reading is supplied, which
beats hard-coding 1/1.5 and hoping.
2. `SignalTracker` runs a constant-velocity Kalman filter per signal.
The filtered level is a denoised measurement; the filtered rate is the
thing you actually want for weather. A finite difference of a 0.05 hPa
noise floor over 5 minutes is garbage. A Kalman rate is not.
"""
from __future__ import annotations
from dataclasses import dataclass, field
from typing import Dict, Optional
import numpy as np
from .physics import saturation_vapour_pressure
@dataclass
class KalmanCV:
"""Constant-velocity Kalman filter for one scalar signal.
State x = [level, rate]. Process noise is the standard continuous
white-noise-acceleration model, so `q` has units of (signal/s^2)^2/s
and is the only knob that matters: raise it to track faster, lower it
to smooth harder.
"""
q: float
r: float
x: np.ndarray = field(default_factory=lambda: np.zeros(2))
P: np.ndarray = field(default_factory=lambda: np.eye(2) * 1e3)
initialised: bool = False
nis: float = 0.0 # normalised innovation squared, for health monitoring
def update(self, z: float, dt: float) -> tuple[float, float]:
if not np.isfinite(z):
return float(self.x[0]), float(self.x[1])
if not self.initialised:
self.x = np.array([z, 0.0])
self.P = np.array([[self.r, 0.0], [0.0, 1e-4]])
self.initialised = True
return z, 0.0
dt = float(max(min(dt, 3600.0), 1e-3))
F = np.array([[1.0, dt], [0.0, 1.0]])
Q = self.q * np.array([[dt ** 3 / 3.0, dt ** 2 / 2.0],
[dt ** 2 / 2.0, dt]])
# predict
self.x = F @ self.x
self.P = F @ self.P @ F.T + Q
# update
H = np.array([[1.0, 0.0]])
y = float(z) - float((H @ self.x)[0])
S = float((H @ self.P @ H.T)[0, 0]) + self.r
K = (self.P @ H.T) / S
self.x = self.x + (K.flatten() * y)
I_KH = np.eye(2) - K @ H
self.P = I_KH @ self.P @ I_KH.T + K @ K.T * self.r # Joseph form, stays PSD
self.nis = (y * y) / S
return float(self.x[0]), float(self.x[1])
@property
def level(self) -> float:
return float(self.x[0])
@property
def rate(self) -> float:
"""Signal units per second."""
return float(self.x[1])
def to_dict(self) -> Dict:
return {"q": self.q, "r": self.r, "x": self.x.tolist(),
"P": self.P.tolist(), "initialised": self.initialised}
@classmethod
def from_dict(cls, d: Dict) -> "KalmanCV":
kf = cls(q=d["q"], r=d["r"])
kf.x = np.array(d["x"], dtype=float)
kf.P = np.array(d["P"], dtype=float)
kf.initialised = bool(d["initialised"])
return kf
class ThermalCompensator:
"""Grey-box removal of SoC self-heating.
Model: T_true = T_sensor - k * (T_cpu - T_sensor), k >= 0.
`k` is updated by recursive least squares whenever `calibrate()` is
called with a trusted reference temperature (a mercury thermometer, a
second logger, or a nearby METAR reading). Until then the configured
prior is used and clamped to a physically sane band, because a runaway
`k` produces confident nonsense, which is worse than a mild bias.
"""
def __init__(self, k0: float = 0.55, k_min: float = 0.15, k_max: float = 1.2,
forgetting: float = 0.98):
self.k = float(k0)
self.k_min, self.k_max = float(k_min), float(k_max)
self.P = 10.0
self.lam = float(forgetting)
self.n_calibrations = 0
self.last_residual = 0.0
def compensate(self, t_sensor: float, t_cpu: float) -> float:
if not (np.isfinite(t_sensor) and np.isfinite(t_cpu)):
return float(t_sensor)
delta = max(t_cpu - t_sensor, 0.0)
return float(t_sensor - self.k * delta)
def calibrate(self, t_sensor: float, t_cpu: float, t_reference: float) -> Dict:
"""One RLS step on k. Regressor is the CPU/sensor gradient."""
phi = max(t_cpu - t_sensor, 0.0)
target = t_sensor - t_reference # what k*phi should equal
denom = self.lam + phi * self.P * phi
gain = (self.P * phi) / denom if denom > 1e-12 else 0.0
residual = target - self.k * phi
self.k = float(np.clip(self.k + gain * residual, self.k_min, self.k_max))
self.P = float((self.P - gain * phi * self.P) / self.lam)
self.P = float(np.clip(self.P, 1e-6, 1e4))
self.n_calibrations += 1
self.last_residual = float(residual)
return {"k": self.k, "residual": self.last_residual, "n": self.n_calibrations}
def to_dict(self) -> Dict:
return {"k": self.k, "P": self.P, "lam": self.lam, "k_min": self.k_min,
"k_max": self.k_max, "n": self.n_calibrations}
@classmethod
def from_dict(cls, d: Dict) -> "ThermalCompensator":
tc = cls(d["k"], d["k_min"], d["k_max"], d["lam"])
tc.P = d["P"]
tc.n_calibrations = d.get("n", 0)
return tc
class HumidityCompensator:
"""Corrects relative humidity for a sensor sitting hotter than the air.
The HTS221 reports RH at its own temperature, but the air you care about is
at the compensated temperature. Vapour pressure is what is conserved between
the two, so
RH_true = RH_sensor * es(T_sensor) / es(T_true)
Because the element runs hot, es(T_sensor) > es(T_true) and an uncorrected
reading is biased low, by several points on a warm board. That term needs no
calibration constant at all: it falls out of the thermal compensation that is
already running.
Measured on real hardware the psychrometric term is the wrong model: against
a reference hygrometer reading 50.4%, this board's HTS221 reported 75.4%, so
it reads HIGH where the thermal argument predicts LOW. The dominant error is
an additive element bias, which is what `offset` corrects, estimated from a
trusted reference by the same one-step RLS used for `k` with the regressor
fixed at 1, so repeated calibrations converge to a weighted mean. The
psychrometric term is therefore off by default and gated on config.
How it fails: calibrate against a reference while the board is cool, then let
CPU load rise, and an offset-only correction drifts because the psychrometric
error grows with the gradient. Applying the vapour-pressure term first is
exactly what keeps `offset` a constant rather than a function of CPU load.
Clamped for the same reason `k` is: one mistyped reference otherwise biases
every reading until you notice.
"""
def __init__(self, offset: float = 0.0, off_min: float = -35.0,
off_max: float = 35.0, forgetting: float = 0.98,
psychrometric: bool = False):
self.psychrometric = bool(psychrometric)
self.offset = float(offset)
self.off_min, self.off_max = float(off_min), float(off_max)
self.P = 10.0
self.lam = float(forgetting)
self.n_calibrations = 0
self.last_residual = 0.0
def _psychrometric(self, rh_sensor: float, t_sensor: float, t_true: float) -> float:
if not self.psychrometric:
return float(rh_sensor)
es_s = float(saturation_vapour_pressure(t_sensor))
es_t = float(saturation_vapour_pressure(t_true))
if not np.isfinite(es_s) or not np.isfinite(es_t) or es_t <= 1e-9:
return float(rh_sensor)
return float(rh_sensor * es_s / es_t)
def compensate(self, rh_sensor: float, t_sensor: float, t_true: float) -> float:
if not (np.isfinite(rh_sensor) and np.isfinite(t_sensor) and np.isfinite(t_true)):
return float(rh_sensor)
base = self._psychrometric(rh_sensor, t_sensor, t_true)
return float(np.clip(base + self.offset, 0.0, 100.0))
def calibrate(self, rh_sensor: float, t_sensor: float, t_true: float,
rh_reference: float) -> Dict:
"""One RLS step on the residual offset. Regressor is 1."""
base = self._psychrometric(rh_sensor, t_sensor, t_true)
target = float(rh_reference) - base
denom = self.lam + self.P
gain = self.P / denom if denom > 1e-12 else 0.0
residual = target - self.offset
self.offset = float(np.clip(self.offset + gain * residual,
self.off_min, self.off_max))
self.P = float(np.clip((self.P - gain * self.P) / self.lam, 1e-6, 1e4))
self.n_calibrations += 1
self.last_residual = float(residual)
return {"offset": self.offset, "residual": self.last_residual,
"n": self.n_calibrations, "psychrometric": base - float(rh_sensor)}
def to_dict(self) -> Dict:
return {"offset": self.offset, "P": self.P, "lam": self.lam,
"off_min": self.off_min, "off_max": self.off_max,
"n": self.n_calibrations, "psychrometric": self.psychrometric}
@classmethod
def from_dict(cls, d: Dict) -> "HumidityCompensator":
hc = cls(d["offset"], d["off_min"], d["off_max"], d["lam"],
d.get("psychrometric", False))
hc.P = d["P"]
hc.n_calibrations = d.get("n", 0)
return hc
class SignalTracker:
"""Bank of Kalman filters plus the compensators, driven at sample rate."""
def __init__(self, cfg):
self.compensator = ThermalCompensator(
cfg.sensor.cpu_heat_k, cfg.sensor.cpu_heat_k_min,
cfg.sensor.cpu_heat_k_max,
)
self.hum_compensator = HumidityCompensator(
cfg.sensor.hum_offset, cfg.sensor.hum_offset_min,
cfg.sensor.hum_offset_max,
psychrometric=cfg.sensor.hum_psychrometric,
)
self.filters = {
"temperature": KalmanCV(cfg.sensor.kalman_q_temp, cfg.sensor.kalman_r_temp),
"humidity": KalmanCV(cfg.sensor.kalman_q_hum, cfg.sensor.kalman_r_hum),
"pressure": KalmanCV(cfg.sensor.kalman_q_press, cfg.sensor.kalman_r_press),
}
self.last_ts: Optional[float] = None
def step(self, ts: float, temp_raw: float, hum: float, press: float,
cpu_temp: float) -> Dict[str, float]:
dt = (ts - self.last_ts) if self.last_ts is not None else 1.0
self.last_ts = ts
temp_c = self.compensator.compensate(temp_raw, cpu_temp)
# RH is reported at the element's temperature, not the air's, so it must
# be moved onto the compensated temperature before it is filtered.
hum_c = self.hum_compensator.compensate(hum, temp_raw, temp_c)
t_lvl, t_rate = self.filters["temperature"].update(temp_c, dt)
h_lvl, h_rate = self.filters["humidity"].update(hum_c, dt)
p_lvl, p_rate = self.filters["pressure"].update(press, dt)
return {
"temp_c": temp_c,
"hum_c": hum_c,
"temp_smooth": t_lvl,
"temp_rate": t_rate * 3600.0, # C per hour
"hum_smooth": h_lvl,
"hum_rate": h_rate * 3600.0, # % per hour
"press_smooth": p_lvl,
"press_rate": p_rate * 3600.0, # hPa per hour, the forecaster's gold
"nis_temp": self.filters["temperature"].nis,
"nis_press": self.filters["pressure"].nis,
}
def to_dict(self) -> Dict:
return {
"compensator": self.compensator.to_dict(),
"hum_compensator": self.hum_compensator.to_dict(),
"filters": {k: v.to_dict() for k, v in self.filters.items()},
"last_ts": self.last_ts,
}
def load_dict(self, d: Dict) -> None:
self.compensator = ThermalCompensator.from_dict(d["compensator"])
# Absent from state files written before humidity compensation existed.
if d.get("hum_compensator"):
self.hum_compensator = HumidityCompensator.from_dict(d["hum_compensator"])
self.filters = {k: KalmanCV.from_dict(v) for k, v in d["filters"].items()}
self.last_ts = d.get("last_ts")
def stuck_sensor_score(values: np.ndarray, window: int = 60) -> float:
"""Fraction of the last `window` samples that are bit-identical.
An HTS221 that latches is the quietest failure mode there is: the
dashboard looks perfect, the model trains happily, and every forecast
is confidently wrong. This is the cheapest possible smoke alarm.
"""
if values.size < 5:
return 0.0
tail = values[-window:]
tail = tail[np.isfinite(tail)]
if tail.size < 5:
return 0.0
return float(np.mean(np.abs(np.diff(tail)) < 1e-9))