ykcheungab
342 lines
13 KiB
Python
342 lines
13 KiB
Python
"""Measure normal-force zero-point drift, live or from a recording.
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Phase 0 of the zero-point plan: quantify the drift before changing the pipeline.
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The number this prints is what the acceptance thresholds get set from, so it is
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deliberately explicit about which rows it used and what it could not conclude.
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Usage
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-----
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Live capture (needs a sensor; writes a recording directory when --out is given):
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python scripts/measure_zero_drift.py --live --seconds 1800 --out D:\\tmp\\idle
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From an existing recording (the directory holding forces.csv):
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python scripts/measure_zero_drift.py --recording <dir> --unit both
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python scripts/measure_zero_drift.py --recording <dir> --warmup 5 --start 10 --stop 60
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What it reports
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---------------
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Per axis, over the analysed window:
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* mean / median / stdev / peak-to-peak, in raw counts and (with --unit N) newtons
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* a least-squares slope in counts/s -- the ramp that "zero drift" actually means
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* a drift ratio (end-third mean minus start-third mean), which is insensitive to
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whether the drift is linear or a slow wander
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* the band left after removing the window mean, i.e. what a perfect single-point
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re-zero would achieve -- this separates "the zero moved" from "the noise is wide"
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The raw columns are ``FN_raw, FX_raw, FY_raw`` and the calibrated ones are
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``FN_N, FX_N, FY_N`` (see ``FORCES_HEADER`` in
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``orisys_app_shared.record.experiment``); rows with ``valid != 1`` are excluded
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rather than read as zeros.
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"""
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from __future__ import annotations
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import argparse
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import csv
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import statistics
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import sys
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from pathlib import Path
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from typing import Sequence
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import numpy as np
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RAW_AXES = ("FN_raw", "FX_raw", "FY_raw")
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NEWTON_AXES = ("FN_N", "FX_N", "FY_N")
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TIME_COLUMN = "t_rel_s"
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VALID_COLUMN = "valid"
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def _load_rows(source: Path) -> list[dict[str, str]]:
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path = source / "forces.csv" if source.is_dir() else source
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if not path.is_file():
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raise SystemExit(f"no forces.csv at {path}")
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with path.open(encoding="utf-8", newline="") as handle:
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return list(csv.DictReader(handle))
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def _column(rows: Sequence[dict[str, str]], name: str) -> np.ndarray:
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values = []
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for row in rows:
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raw = row.get(name)
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try:
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values.append(float(raw)) # type: ignore[arg-type]
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except (TypeError, ValueError):
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values.append(np.nan)
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return np.asarray(values, dtype=np.float64)
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def _window(
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rows: list[dict[str, str]],
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*,
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start: float | None,
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stop: float | None,
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warmup: float,
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) -> tuple[np.ndarray, list[dict[str, str]]]:
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times = _column(rows, TIME_COLUMN)
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valid = _column(rows, VALID_COLUMN)
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mask = np.ones(times.shape, dtype=bool)
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if times.size:
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mask &= times == times # drop NaN timestamps
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if start is not None:
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mask &= times >= float(start)
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if stop is not None:
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mask &= times <= float(stop)
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# ``valid`` is authoritative: an invalid row is not a zero reading.
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mask &= (valid == 1) | np.isnan(valid)
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kept = [row for row, keep in zip(rows, mask) if keep]
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if not kept:
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return np.asarray([], dtype=np.float64), []
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times = np.asarray([float(row[TIME_COLUMN]) for row in kept], dtype=np.float64)
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if warmup > 0 and times.size:
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t0 = times[0]
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kept = [row for row in kept if float(row[TIME_COLUMN]) - t0 >= warmup]
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times = np.asarray([float(row[TIME_COLUMN]) for row in kept], dtype=np.float64)
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return times, kept
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def _describe(label: str, values: np.ndarray, times: np.ndarray) -> dict[str, float]:
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finite = values[np.isfinite(values)]
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if finite.size == 0:
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return {"axis": label, "n": 0}
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mean = float(finite.mean())
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median = float(np.median(finite))
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# A min-to-max span does not shrink when a constant is removed, so it cannot
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# answer "what would a re-zero achieve". The robust band and the inter-
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# percentile width can, and they are what the noise is measured against in
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# the existing perf analysis.
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centred = finite - median
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band_1sigma = float(
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(np.percentile(centred, 84.1) - np.percentile(centred, 15.9)) / 2.0
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)
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width_99 = float(np.percentile(finite, 99.5) - np.percentile(finite, 0.5))
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slope = float("nan")
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if times.size == finite.size and times.size > 2 and float(times[-1] - times[0]) > 0:
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slope = float(np.polyfit(times - times[0], finite, 1)[0])
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third = max(1, finite.size // 3)
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drift_ratio = float(finite[-third:].mean() - finite[:third].mean())
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return {
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"axis": label,
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"n": int(finite.size),
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"mean": mean,
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"median": median,
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"stdev": float(finite.std(ddof=0)),
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"p2p": float(finite.max() - finite.min()),
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"band_1sigma": band_1sigma,
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"width_99": width_99,
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"slope_per_s": slope,
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"drift_ratio": drift_ratio,
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}
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def _print_table(title: str, stats: list[dict[str, float]], unit: str) -> None:
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usable = [s for s in stats if s.get("n")]
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print(f"\n=== {title} ===")
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if not usable:
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print(" no rows in the analysed window")
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return
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print(
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f" {'axis':<8} {'n':>7} {'mean':>13} {'median':>13} {'stdev':>12} "
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f"{'band1s':>11} {'w99':>11} {'slope/s':>11} {'drift':>11} [{unit}]"
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)
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for s in usable:
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print(
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f" {s['axis']:<8} {s['n']:>7} {s['mean']:>13.3f} {s['median']:>13.3f} "
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f"{s['stdev']:>12.3f} {s['band_1sigma']:>11.3f} {s['width_99']:>11.3f} "
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f"{s['slope_per_s']:>11.4f} {s['drift_ratio']:>11.3f}"
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)
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print(
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" slope/s = least-squares ramp (the drift rate)\n"
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" band1s = robust 1-sigma half-width about the median\n"
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" w99 = 0.5-99.5 percentile width (tail-resistant spread)\n"
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" drift = mean(last third) - mean(first third): moved, not just noisy"
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)
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def _analyse(rows: list[dict[str, str]], args: argparse.Namespace) -> int:
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times, kept = _window(
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rows, start=args.start, stop=args.stop, warmup=args.warmup
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)
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print(f"recording rows : {len(rows)}")
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print(f"analysed rows : {len(kept)}")
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if times.size:
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dt = np.diff(times)
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print(
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f"analysed window : {times[0]:.3f} .. {times[-1]:.3f} s "
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f"({times[-1] - times[0]:.3f} s)"
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)
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if dt.size and dt[dt > 0].size:
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rate = 1.0 / float(np.median(dt[dt > 0]))
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print(f"effective sample rate : {rate:.2f} Hz")
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if len(kept) < 30:
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print(
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"\nNOTE: fewer than 30 analysed rows. This cannot characterise a slow\n"
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" zero drift -- capture an idle run of at least several minutes."
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)
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if args.unit in ("raw", "both"):
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_print_table(
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"raw counts (pre-calibration)",
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[_describe(axis, _column(kept, axis), times) for axis in RAW_AXES],
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"counts",
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)
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if args.unit in ("N", "both"):
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_print_table(
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"newtons (what the operator sees)",
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[_describe(axis, _column(kept, axis), times) for axis in NEWTON_AXES],
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"N",
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)
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if args.out:
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out = Path(args.out)
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out.parent.mkdir(parents=True, exist_ok=True)
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with out.open("w", encoding="utf-8", newline="") as handle:
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writer = csv.writer(handle)
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writer.writerow(
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["axis", "unit", "n", "mean", "median", "stdev", "band_1sigma",
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"width_99", "slope_per_s", "drift_ratio"]
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)
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groups = []
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if args.unit in ("raw", "both"):
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groups.append((RAW_AXES, "counts"))
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if args.unit in ("N", "both"):
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groups.append((NEWTON_AXES, "N"))
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for axes, unit in groups:
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for axis in axes:
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s = _describe(axis, _column(kept, axis), times)
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if not s.get("n"):
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continue
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writer.writerow([
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s["axis"], unit, s["n"], f"{s['mean']:.6f}",
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f"{s['median']:.6f}", f"{s['stdev']:.6f}",
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f"{s['band_1sigma']:.6f}", f"{s['width_99']:.6f}",
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f"{s['slope_per_s']:.6f}", f"{s['drift_ratio']:.6f}",
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])
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print(f"\nwrote {out}")
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return 0
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def _capture_live(args: argparse.Namespace) -> int:
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"""Sample a real sensor with no load applied.
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Uses only the public ``read_info``/``disconnect`` surface, so this keeps
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working if the internals move.
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"""
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import time as _time
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from orisys import Sensor
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sensor = Sensor(
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"external",
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config_name=args.config,
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verbose=args.verbose,
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backend=args.backend,
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)
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seconds = float(args.seconds)
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period = 1.0 / float(args.sample_rate)
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rows: list[tuple[float, float, float, float, float, float, float]] = []
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try:
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print(
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f"capturing {seconds:.0f}s at ~{args.sample_rate:.0f} Hz from config "
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f"{args.config!r} ({args.backend}); keep the sensor unloaded"
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)
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t0 = _time.monotonic()
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while True:
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elapsed = _time.monotonic() - t0
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if elapsed >= seconds:
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break
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raw = sensor.read_info(
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sensor.info.FNORMAL_RAW,
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sensor.info.FSHEARX_RAW,
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sensor.info.FSHEARY_RAW,
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)
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newtons = sensor.read_info(
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sensor.info.FNORMAL,
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sensor.info.FSHEARX,
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sensor.info.FSHEARY,
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)
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rows.append((elapsed, *[float(v) for v in raw], *[float(v) for v in newtons]))
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_time.sleep(max(0.0, period - ((_time.monotonic() - t0) - elapsed)))
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finally:
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sensor.disconnect()
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if not rows:
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print("no samples captured (external-frame mode may need a frame source)")
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return 1
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times = np.asarray([row[0] for row in rows], dtype=np.float64)
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print(f"\ncaptured {len(rows)} samples over {times[-1]:.1f}s")
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if args.out:
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out = Path(args.out)
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out.mkdir(parents=True, exist_ok=True)
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path = out / "forces.csv"
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with path.open("w", encoding="utf-8", newline="") as handle:
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writer = csv.writer(handle)
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writer.writerow(
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["session_id", "frame_id", TIME_COLUMN, *RAW_AXES, *NEWTON_AXES,
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VALID_COLUMN, "calibration_id"]
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)
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for index, row in enumerate(rows):
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t_rel, *rest = row
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writer.writerow(
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[0, index, f"{t_rel:.6f}", *[f"{v:.6f}" for v in rest], 1, ""]
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)
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print(f"wrote {path}")
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return 0
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_print_table(
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"live raw counts",
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[
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_describe(axis, np.asarray([row[1 + i] for row in rows]), times)
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for i, axis in enumerate(RAW_AXES)
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],
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"counts",
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)
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_print_table(
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"live newtons",
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[
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_describe(axis, np.asarray([row[4 + i] for row in rows]), times)
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for i, axis in enumerate(NEWTON_AXES)
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],
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"N",
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)
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return 0
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def main(argv: Sequence[str] | None = None) -> int:
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parser = argparse.ArgumentParser(
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description="Measure normal-force zero-point drift (Phase 0)."
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)
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source = parser.add_mutually_exclusive_group(required=True)
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source.add_argument("--recording", type=Path,
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help="recording directory or forces.csv path")
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source.add_argument("--live", action="store_true",
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help="capture from a Sensor instead (external-frame mode)")
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parser.add_argument("--seconds", type=float, default=1800.0,
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help="live capture length (default 1800)")
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parser.add_argument("--sample-rate", type=float, default=30.0,
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help="live polling rate Hz (default 30)")
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parser.add_argument("--config", default="box", help="sensor config for --live")
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parser.add_argument("--backend", default="cpu", help="poisson backend for --live")
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parser.add_argument("--unit", choices=("raw", "N", "both"), default="both")
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parser.add_argument("--start", type=float, default=None, help="window start (s)")
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parser.add_argument("--stop", type=float, default=None, help="window stop (s)")
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parser.add_argument("--warmup", type=float, default=0.0,
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help="discard this many seconds from the window start")
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parser.add_argument("--out", default=None,
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help="write the per-axis table to this CSV path, or the "
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"capture directory when used with --live")
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parser.add_argument("--verbose", action="store_true")
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args = parser.parse_args(argv)
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if args.live:
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return _capture_live(args)
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return _analyse(_load_rows(args.recording), args)
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if __name__ == "__main__":
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sys.exit(main())
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