Commit Graph
12 Commits
Author SHA1 Message Date
kemal 9a1033973d Treat the board being moved as a regime change, from the fused IMU attitude
The accelerometer and gyroscope were logged and never used. They measure
nothing about weather, but they do measure the one thing about this station
that nothing else can see: whether the sensor is still where it was.

Measured over four and a half days on the real station, four genuine
movements each stepped the temperature by a median of 1.02 C, against an
ordinary fifteen minute change of 0.107 C with a 95th percentile of 0.841.
A move therefore lands past the 95th percentile of normal variation. The
heads carry about 55 hours of memory, so an undeclared move contaminates two
days of training with a discontinuity they will try to fit rather than ignore.
This now gets the same treatment set_environment gives a window being opened,
because it is the same event: the coupling between the sensor and what it is
measuring changed, and nothing in the data says so.

Three choices in here were made by measurement, and the obvious one was wrong.

Raw accelerometer looks like the natural input and is not. Over the same
record a gravity-vector detector fires 112 times against this one's 4, because
RTIMULib's gyro fusion removes exactly the desk vibration a bare accelerometer
picks up. The fused pitch and roll have a p99 sample-to-sample noise of 0.0001
degrees, so a one degree trigger carries four decades of headroom.

Yaw and compass are excluded. They are the only attitude outputs that depend
on the magnetometer, and indoors the magnetometer is measuring the building.

RTIMULib restarts its fusion from a default attitude when SenseHat is
reconstructed, which put an 18 degree step in the record on every one of this
station's seven service restarts. Without a settle window every deploy would
queue a retrain. 300 seconds rather than 180: one artifact appeared three
minutes after a restart, still converging. Replayed against the full record
the detector finds 4 genuine movements and leaks 0 artifacts.
2026-08-20 07:23:08 +01:00
kemal 3dd45f7ebf Joystick labelling, a clock guard, and throttle logging
Three things the hardware offers that the code ignored.

The joystick has never had a line of code. Left records a dry label, right a
wet one, middle cycles the LED scene, and a full-panel flash acknowledges the
press because a headless box gives no other sign and a button you cannot tell
worked gets pressed twice. Precipitation is the weakest head in the bank and
strong labels are its binding constraint: this station has 80 of them against
thousands of proxy ones, entirely because the only label control lives in a web
page, and a web page is not where anyone is standing when it starts raining.

The board has no RTC, so a power cut without a network gives a clock somewhere
in 1970 on the next boot. Solar elevation, the diurnal harmonics and a sample's
position on the 5-minute grid then all lie with complete confidence, and unlike
a gap in the record the damage cannot be identified afterwards. train() now
refuses a clock below 2025 or one that has stepped behind the newest stored
row, and logs the refusal rather than training on fiction.

Undervoltage and thermal capping both shift the SoC temperature, which is the
regressor in the self-heating compensation, so a weak power supply presents as
an unexplained temperature bias rather than as anything resembling a power
problem. get_throttled is now sampled hourly and logged when set.

Measured and deliberately not done: colour features. r, g and b are logged and
74% of rows carry usable colour, but adding blue/red, green/red and saturation
made MAE 1.50% worse and helped in only 13 of 72 cases. Three more regressors
on a 33-feature model whose longest horizon trains on 13 independent pairs is
straightforwardly overfitting. That also prompted a sweep of the RLS prior and
forgetting factor in both directions; delta = 100 with lambda = 0.9985 is a
local optimum on both axes, so neither moved.
2026-08-19 19:45:47 +01:00
kemal f1647788c8 Learner hygiene: Hedge loss scale, look-ahead residual, conformal minimum
Three changes to ForecastHead and the conformal calibrator, each measured
walk-forward on real data over seven train splits.

Hedge normalised its losses by the current sample's worst loss, so on a quiet
step where every member agreed to within 0.01 C whichever happened to be worst
still took the full exp(-eta) penalty, exactly as if it had been wrong by 5 C.
The regret bound assumes a fixed loss range, not a per-sample one, and the
symptom was weights that jumped around with no relation to horizon. Normalising
by the running member MAE instead is worth 1.81% of MAE, better on 106 of 126
heads, coverage unchanged.

The residual handed to the conformal calibrator was computed after this
sample's loss had already moved the weights, so it was better than anything the
forecaster could produce and the intervals were calibrated about 2% too narrow.
Coverage survived only because ACI notices the extra misses and reopens the
band, a correction that should never have been needed. Scoring the blend with
the pre-update weights leaves MAE untouched, as it must, and widens the
intervals 2% to the honest width.

The conformal quantile refused to produce a band below 20 scores. That number
is arbitrary: the (1-alpha) empirical quantile is the ceil((k+1)(1-alpha))-th
of k order statistics, so alpha = 0.10 needs 9. The 20 became actively harmful
in the previous commit but one, because striding pairs by the horizon leaves a
long-horizon head about 13 scores per refit. Twelve of eighteen heads therefore
fell through to 1.645*sigma with sigma from an unconstrained x'Px, giving bands
of +/- 45 C and +/- 115% relative humidity on a young station. Those cover, by
being absurd, which is why the backtest never flagged them: a long walk-forward
passes 20 scores early and never looks back. After the change all eighteen
heads have a band from the first fit, +/- 3.1 C and +/- 7.7% in the same place.

Also measured and deliberately not done: adding the Kalman level variance to
the predictive spread. It moves sigma by 0.06% at the shortest horizon and
0.00% everywhere else, so the plumbing to carry it through three files buys
nothing.
2026-08-19 19:38:34 +01:00
kemal 41a46ae14a Take model tuning from config too, not from the saved state
The companion to the Kalman fix. RecursiveLeastSquares.from_dict and
AdaptiveConformal.from_dict restore lambda, delta, alpha, gamma and the
conformal window alongside their data, and load_dict replaces the
config-built heads with those, so every one of those knobs was immutable on
any station that already had state. Editing config.yaml and restarting looks
exactly like a change with no effect, which is the failure mode that cost real
time on the Kalman side of this before it was found.

Only the estimate is state now. Weights, covariances and conformal scores are
restored; tuning is re-applied from config on every load. The conformal deques
are rebuilt when the configured window changes, preserving their contents.

load_dict also skips heads for a target or horizon this build no longer has,
rather than resurrecting them from a stale file.

Found while implementing a damped-trend ensemble member, which was then
abandoned: see the following note.
2026-08-19 19:31:03 +01:00
kemal 3f41881c64 Take Kalman tuning from config, not from the saved state
q and r were written into station_state.json and restored over the configured
values, so tuning was effectively immutable in the field. This was found the
expensive way: the retune in the previous commit was deployed, the service
restarted cleanly, and the filters carried on with q = 2e-6 because that is
what the state file said. Measured median rate afterwards was 14.4 C/h against
12.4 before, which is to say nothing happened.

Only the estimate is state. x, P and initialised are restored; q and r now
come from config every time. P may be momentarily inconsistent with a changed
q, which costs a few hundred samples of reconvergence and is far cheaper than
a configuration change that appears to work and does not.

load_dict also now skips filters this build no longer has, rather than
resurrecting them from an older state file.
2026-08-19 19:22:49 +01:00
kemal 40f934901d Retune the Kalman process noise, and fuse the two thermometers
Two changes to the same signal path, one large and one small.

The large one: all three filters were tuned to track one to three decades
faster than their signals move. In a still room the temperature filter
reported a median rate of 12.4 C/h while the air moved 0.4 C/h, and it
overshot a real -36 C/h event by 77%. Sweeping q against the RMSE of the
reported rate versus the true rate, using noise measured on the board
(temperature 0.088 C, pressure 0.022 hPa, humidity 0.40 %):

   temperature   6.45 -> 0.37 C/h RMSE     2e-6 -> 1e-9
   pressure      2.15 -> 0.24 hPa/h RMSE   1e-5 -> 1e-8
   humidity     27.94 -> 3.55 %/h RMSE     5e-5 -> 2e-8

Tracking does not suffer. Lag against a genuine 2 C/h ramp is 0.003 C at both
the old and new values, and the peak response to a five-minute event moves
closer to the truth rather than further from it, because the overshoot goes
away. What is given up is response to sub-minute transients, which for a
station forecasting fifteen minutes to a day ahead is noise to reject.

This matters most for pressure, whose tendency drives the precipitation
forecast, and which was the worst tuned of the three.

config.yaml shadowed kalman_q_temp, so editing the dataclass alone changed
nothing. All six values are now listed there with that hazard spelled out,
because a silent shadow cost real time here.

The small one: temp_raw was the plain average of two thermometers whose
white-noise sds differ by 7x (LPS25HB 0.007 C, HTS221 0.049 C), which throws
the quiet one away. Inverse-variance weighting cuts the raw noise 3.5x.

The trap is that the chips do not agree. They sit at different distances from
the SoC and stand about 1.3 C apart, so weighting by variance alone drags
temp_raw 0.48 C onto the LPS25HB, which after the 1.55x gain of the inverse
compensator is 0.75 C of silent bias on every reading, since k was fitted
against the mean of the two. The gradient is therefore tracked and removed
before weighting and only the deviations are fused: measured mean shift
0.0001 C, noise still 3.5x lower. The tracked gradient is retained because it
is a second observation of self-heating.

Also corrected: the earlier claim that the HTS221 was the quieter channel was
wrong, taken from twelve samples at a cadence slow enough that real drift
dominated. At 0.5 s over 120 samples the LPS25HB is quieter by 7x and takes
98% of the weight.
2026-08-19 19:14:46 +01:00
kemal e3176e29c9 Stride training pairs by the horizon instead of by the grid row
fit() trained every head on every consecutive grid row. At the 1 d horizon on
a 5-minute grid adjacent pairs share 287 of their 288 samples, so the filter
was handed the same outcome 288 times and RLS with forgetting read each one as
fresh evidence:

   horizon  steps  overlap  independent events in a 400-score window
       15m      3   66.7%    133.3
        1h     12   91.7%     33.3
        3h     36   97.2%     11.1
        6h     72   98.6%      5.6
       12h    144   99.3%      2.8
        1d    288   99.7%      1.4

The day-ahead head was therefore fitted on roughly two independent outcomes by
a filter carrying 667 updates of memory, and its interval was a 90th percentile
of a sample of size one.

This is not a compute shortcut that trades accuracy for speed. Measured
walk-forward on four days of real station data and averaged over five train
splits, striding improves every horizon past fifteen minutes:

   15m  +0.6%   1h -12.2%   3h -31.7%   6h -33.3%   12h -39.5%   1d -14.4%

with coverage unchanged at 87 to 92%, and the fit 11.6x faster. The redundancy
was not merely wasted work, it was collapsing P onto the one direction the
repeated sample excited.

The stride phase rotates each refit and is persisted, so a long-lived station
eventually trains on every offset rather than seeing one sample in 288 forever,
and a restart does not pin it to phase 0. A floor relaxes the stride when a
long horizon on a short record would otherwise yield one or two pairs; 12 was
chosen by sweeping it across five splits rather than picked.

Single-split runs showed 10 to 17% regressions at the 1 d horizon that moved
with the parameter. Averaging over five splits removed them, which is the
expected result for a head fitted and scored on under two independent
outcomes. That horizon cannot be evaluated on a four-day record and was not
tuned against.

Incidentally, this also retires the parallel-retrain idea: the Pi's 42 s
retrain becomes a few seconds, and multiprocessing inside a 280 MB cap buys
nothing for a job that short.
2026-08-19 18:50:07 +01:00
kemal bda42a0468 Log both Sense HAT thermometers, and migrate schemas that predate them
The board carries two independent thermometers and the code averaged them
into temp_raw without ever recording either. Measured over 12 samples on a
real station: HTS221 30.973 C at sd 0.060, LPS25HB 29.810 C at sd 0.443, a
standing gradient of 1.163 C with the SoC at 44.55 C.

Two things follow from that and neither is possible without the raw channels.
A plain average of a quiet sensor and one seven times noisier lands at sd
0.223 where inverse-variance weighting reaches 0.060, and the gradient between
two chips at different distances from the SoC is a second observation of
self-heating that could identify the compensator's k with no reference
thermometer. Both need history, and history cannot be backfilled, so the
columns land on their own ahead of the work that consumes them.

CREATE TABLE IF NOT EXISTS is a no-op against a table that already exists, so
adding to COLUMNS would have reached a fresh install and silently missed every
station already running, then surfaced as an OperationalError inside
insert_telemetry. That sits on the sample loop, so it takes a station down
rather than leaving a gap. Store now reconciles the table against COLUMNS on
open, which makes every future column addition safe rather than just this one.

The simulator gains the same two channels, with couplings solved so their
forward models average to exactly the k = 0.55 the compensator is tuned
against. Aggregate behaviour is unchanged; only the per-channel detail is new.
Simulated temp_raw noise does rise from 0.05 to 0.223, which is not a
regression but the end of an over-optimistic figure: it was modelling the
quiet sensor and calling it the average.
2026-08-19 18:41:46 +01:00
kemal 485affe956 Fix the runaway forecasts: refits accumulated, and annual terms fitted too early
Reported from a real station after 1.5 days: a six hour temperature forecast of
53 C in a 24 C room, and 9 C at one day, both carrying a plus or minus of 0.43.
Confidently wrong is the one failure this project is supposed to refuse.

Root cause. fit() replayed history into the live RLS on every retrain tick and
never reset, so 453 grid rows had produced 64,676 updates in a day and a half.
RLS with forgetting reads every update as fresh evidence, so the model believed
it had a hundred times the data it had: P collapsed, in-sample error looked
excellent, and the weights drifted without bound in directions the data never
excited. Measured: cond(P) 3.1e9 and ||theta|| 1680 against a median |theta| of
1.67. A refit now starts from the prior, which makes retraining idempotent.
Across 25 refits on the real data ||theta|| holds at 11.35, drifting 0.03, where
before it grew without limit.

The two largest weights were sin_doy and cos_doy at +1174 and +1191. Annual
harmonics were in the design matrix from the first sample, where they are
near-constant, near-collinear with each other and with the bias, and a
rank-deficient regressor is what RLS answers with enormous cancelling weights.
They are now held at zero until the record spans the same 120 days the
climatology fit already requires, because a day and a half of data says nothing
whatsoever about the season.

Also raised the standardiser's variance floor from 1e-8, which only caught a
bit-exactly constant column, to 1e-3. A feature that merely barely moves was
being divided by its own noise.

The conformal calibrators and Hedge weights are deliberately not reset by a
refit: those are earned from scored forecasts, not from this regression.

Backtest unchanged within noise, coverage still 89 to 91 across all 18 heads.
Four regression tests added, including that refitting the same history twice
must give the same model.
2026-08-17 08:15:45 +01:00
kemal 4cca40388f Heated environment: a thermostat member in the forecast ensemble
A room held at a setpoint is a different process from one left to drift. It is
a closed loop, and persistence, the baseline everything here is scored against,
is the wrong statement about it: the truth is not that it stays where it is, it
is that it returns to the setpoint.

So site.heating adds a fourth ensemble member, first order because that is what
a controlled system is:

    dT_set(h) = (T_set - T_now) * (1 - exp(-h / tau))

Humidity follows and is the part that is easy to get wrong. Heating adds no
moisture, so vapour pressure is conserved and not relative humidity:

    RH(h) = RH_now * es(T_now) / es(T_now + dT_set(h))

Warm the air and RH falls although nothing was dried, which is why a heated
house in winter is dry. The test asserts the dew point is unchanged to 1e-6.
Pressure gets zero: a thermostat cannot move the synoptic field.

Offered, not imposed. Hedge scores this member on realised error like any
other, so a wrong tau or a stale setpoint costs accuracy and gets down-weighted
rather than quietly biasing every forecast. Verified: on history with no
heating the ensemble assigned it weight 0.000. With heating off it returns zero
and is identical to persistence.

Going from three members to four means old saved heads must migrate.
from_dict reinitialises weights and member_mae. I missed member_mae first time
and it did not fail on load, it failed later inside learn() on a broadcast
error, which is a much worse place to find out; the migration test now covers
both and calls learn() to prove it.

Settings tab gains the toggle, setpoint and time constant. Turning heating on
or off is treated as a regime change like a door: discontinuity marker plus a
queued retrain.
2026-08-16 16:39:54 +01:00
kemal db0f877052 Fix flaky row-count assertion in the recompute tests
Equality on the row count raced the live sample loop under TestClient, which
legitimately inserts rows mid-test. Now asserts no rows are lost, which is the
property that matters. Run three times to confirm it is stable.
2026-08-15 23:05:05 +01:00
kemal 98210bff8f Six enhancements: recompute, markers, vendoring, tests, nerd stats, DS18B20
1. POST /api/recompute re-derives every compensated column from the untouched
   raw values, removing the step a calibration otherwise leaves through the
   history. Possible because temp_raw, cpu_temp and hum are never overwritten.
   Idempotent by construction and tested per row: 0 of 6051 rows change on a
   second run. 6069 rows in 0.25 s here, so a few seconds on the Pi.

2. Calibration now emits a 'discontinuity' event alongside the calibration log,
   so downstream views can find the boundary without parsing prose.

3. Vendored Tailwind, Chart.js, hammer, the zoom plugin, KaTeX with its 20
   woff2 faces, and both Google fonts into ashvale/static, served by the
   station. 1.4 MB. Verified with every non-localhost request aborted in the
   browser: zero external requests, equations still render, fonts still load.
   The dashboard no longer needs internet.

4. 54 pytest cases over the pure numerics: physics closed forms and round
   trips, both compensator inverse properties, the Kalman covariance
   invariants and NIS consistency, the RLS trace cap under a deliberately
   unexcited regressor, conformal coverage, and the Zambretti ordering. Wired
   into CI after the seed step so the recompute cases have history. Writing
   them caught my own sign error on the conformal update: a hit raises alpha
   and narrows the band, which reads backwards until you follow it through.

5. Stats for Nerds gains the condition number of each head's covariance, a
   standardised innovation histogram per Kalman filter from a bounded 600
   sample ring buffer, and a reliability strip of realised against nominal
   coverage. All arithmetic on data already in memory.

6. OutdoorProbe reads a DS18B20 over the kernel 1-Wire driver, no new
   dependency. Polled on its own slower cadence because the sensor blocks for
   up to 750 ms during conversion, which would eat a third of the 2 s sample
   budget. Rejects the 85000 power-on sentinel and out-of-range values, and
   reports age so a dead probe cannot masquerade as fresh.
2026-08-15 22:39:37 +01:00