research(R6.2.3): chest-centric placement — +26.9 pp coverage gain for vital-signs cogs (#726)

Direct follow-up from R6.1 (chest contributes 27.6% of CSI energy,
5x per-limb value, limbs are confound not signal).

R6.2.3 re-runs R6.2's placement search with chest-only target zones
(40x40 cm patches at expected chest positions) vs body-footprint zones
(R6.2's default full-area definition).

Headline result:

| Configuration              | Coverage | Placement                  |
|----------------------------|---------:|----------------------------|
| Body-centric (R6.2 default)|   49.3%  | (4.25,0)-(0,3.25), 5.35 m  |
| CHEST-CENTRIC (R6.2.3 new) |   82.4%  | (2.0,0)-(4.5,5),   5.59 m  |

Cross-eval:
- Body-optimal on chest zones:    55.5%
- Chest-targeting GAIN on chest:  +26.9 pp
- Chest-optimal on body zones:    40.3% (-9.0 pp loss)

The two strategies are genuinely different. Same engine, different
zones.

Per-cog deployment recommendation surfaced:
- --target-mode=body  (default): cog-person-count, cog-pose, cog-presence
- --target-mode=chest (new):     cog-vital-signs, cog-breathing, cog-HR
- --target-mode=extremity (future): gesture detection

~20 LOC change to R6.2 CLI.

R14 vertical-specific:
- V1 stress-responsive lighting:        chest mode
- V2 adaptive HVAC (presence+breathing): mixed
- V3 attention-respecting conversation:  chest mode

R6.2.3 surfaces a per-cog config that empathic-appliance products
need at install time.

Why placements differ: when target ~ envelope width, envelope can cover
it entirely; when target >> envelope, placement must compromise. 40 cm
Fresnel envelope @ 5 m link comfortably covers 40 cm chest patches but
must spread to cover 3 m^2 bed.

Composes:
- R6.1 motivated this tick
- R6.2 / R6.2.1 / R6.2.2 -- orthogonal extensions
- R14 V1/V3 should use chest mode
- R12 PABS improves body-position-detection scenarios

Honest scope:
- Chest positions approximated
- 2D still (3D chest-centric = R6.2.3.1 follow-up)
- Single subject (multi-subject = union of chest envelopes)
- Per-cog zone schema is deployment-time

Coordination: ticks/tick-23.md, no PROGRESS.md edit.
This commit is contained in:
rUv
2026-05-22 04:43:34 -04:00
committed by GitHub
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#!/usr/bin/env python3
"""R6.2.3 — Chest-centric target zones for placement search.
See docs/research/sota-2026-05-22/R6_2_3-chest-centric-placement.md.
R6.1 quantified that the chest contributes 27.6% of the total CSI
energy from a standing human -- 5x any single limb. R15's gait /
breathing / RCS primitives are all dominated by chest dynamics.
This tick re-runs R6.2's placement search with chest-only target zones
instead of full-body zones, and asks:
Does the optimal placement change when we target chest specifically?
How much coverage is gained by aiming at the chest envelope alone?
If the answer is "no change", placement-time chest centring is
unnecessary. If the answer is "significant change", R6.2's CLI tool
should learn pose-aware zone definitions.
Pure NumPy.
"""
from __future__ import annotations
import argparse
import json
from pathlib import Path
import numpy as np
C = 2.998e8
def wavelength_m(freq_ghz: float) -> float:
return C / (freq_ghz * 1e9)
def in_first_fresnel(x, y, tx, rx, wavelength):
r1 = np.sqrt((x - tx[0])**2 + (y - tx[1])**2)
r2 = np.sqrt((x - rx[0])**2 + (y - rx[1])**2)
direct = np.linalg.norm(tx - rx)
return (r1 + r2) <= (direct + wavelength / 2)
def coverage(tx, rx, target_zones, wavelength, resolution=0.05):
per_zone = {}
total_pts, total_covered = 0, 0
for name, x0, y0, w, h in target_zones:
xs = np.arange(x0, x0 + w, resolution)
ys = np.arange(y0, y0 + h, resolution)
gx, gy = np.meshgrid(xs, ys)
mask = in_first_fresnel(gx.ravel(), gy.ravel(), tx, rx, wavelength)
n_pts = len(gx.ravel())
per_zone[name] = {
"area_m2": float(n_pts * resolution ** 2),
"covered_m2": float(mask.sum() * resolution ** 2),
"coverage_fraction": float(mask.mean()),
}
total_pts += n_pts
total_covered += mask.sum()
return {
"total_coverage_fraction": float(total_covered / total_pts) if total_pts > 0 else 0,
"per_zone": per_zone,
}
def candidate_positions(room_w, room_h, step):
cands = []
for x in np.arange(0, room_w + 0.001, step):
cands.append(np.array([x, 0.0]))
cands.append(np.array([x, room_h]))
for y in np.arange(step, room_h, step):
cands.append(np.array([0.0, y]))
cands.append(np.array([room_w, y]))
return cands
def search(target_zones, room_w, room_h, freq_ghz, step):
lam = wavelength_m(freq_ghz)
cands = candidate_positions(room_w, room_h, step)
best = {"score": -1, "tx": None, "rx": None, "per_zone": None}
for i, tx in enumerate(cands):
for j, rx in enumerate(cands):
if j <= i: continue
if np.linalg.norm(tx - rx) < 1.0: continue
cov = coverage(tx, rx, target_zones, lam)
if cov["total_coverage_fraction"] > best["score"]:
best = {
"score": cov["total_coverage_fraction"],
"tx": tx.tolist(), "rx": rx.tolist(),
"link_m": float(np.linalg.norm(tx - rx)),
"per_zone": cov["per_zone"],
}
return best
def main():
parser = argparse.ArgumentParser()
parser.add_argument("--out", default="examples/research-sota/r6_2_3_chest_centric_results.json")
args = parser.parse_args()
room_w, room_h = 5.0, 5.0
freq = 2.4
step = 0.25
# === BODY-CENTRIC zones (R6.2 default) ===
# Bed (full lying area), chair (full sitting area), desk (full sitting area)
body_zones = [
("bed", 1.5, 0.5, 2.0, 1.5),
("chair", 3.5, 3.5, 0.8, 0.8),
("desk", 0.2, 2.5, 1.0, 0.6),
]
# === CHEST-CENTRIC zones (R6.2.3 new) ===
# The chest is approximately the upper-torso 40x30 cm region of the body.
# Bed lying: chest at (2.5, 1.0) ± 30 cm
# Chair sitting: chest at (3.9, 3.9) ± 20 cm
# Desk: chest at (0.7, 2.8) ± 20 cm
chest_zones = [
("bed_chest", 2.2, 0.8, 0.6, 0.4), # 60x40 cm chest patch
("chair_chest", 3.7, 3.7, 0.4, 0.4), # 40x40 cm
("desk_chest", 0.5, 2.7, 0.4, 0.2), # 40x20 cm
]
print(f"Room: {room_w}x{room_h} m, freq {freq} GHz")
print()
print("=== Body-centric placement search ===")
best_body = search(body_zones, room_w, room_h, freq, step)
print(f" Best Tx: {best_body['tx']}, Rx: {best_body['rx']}")
print(f" Link length: {best_body['link_m']:.2f} m")
print(f" Total body-area coverage: {best_body['score']*100:.1f}%")
print()
print("=== Chest-centric placement search ===")
best_chest = search(chest_zones, room_w, room_h, freq, step)
print(f" Best Tx: {best_chest['tx']}, Rx: {best_chest['rx']}")
print(f" Link length: {best_chest['link_m']:.2f} m")
print(f" Total chest-area coverage: {best_chest['score']*100:.1f}%")
print()
# Cross-eval: how does the body-optimal placement perform on chest zones?
lam = wavelength_m(freq)
body_pl_on_chest = coverage(
np.array(best_body["tx"]), np.array(best_body["rx"]), chest_zones, lam
)
chest_pl_on_body = coverage(
np.array(best_chest["tx"]), np.array(best_chest["rx"]), body_zones, lam
)
print("=== Cross-evaluation ===")
print(f" Body-optimal placement on CHEST zones: {body_pl_on_chest['total_coverage_fraction']*100:.1f}%")
print(f" Chest-optimal placement on BODY zones: {chest_pl_on_body['total_coverage_fraction']*100:.1f}%")
print()
chest_gain_pp = (best_chest["score"] - body_pl_on_chest["total_coverage_fraction"]) * 100
body_loss_pp = (best_body["score"] - chest_pl_on_body["total_coverage_fraction"]) * 100
print(f" Chest-targeting gain on chest zones: {chest_gain_pp:+.1f} pp")
print(f" Body-loss when using chest-optimal: {body_loss_pp:+.1f} pp")
print()
# Verdict
if abs(np.array(best_chest["tx"]) - np.array(best_body["tx"])).sum() < 0.6 and \
abs(np.array(best_chest["rx"]) - np.array(best_body["rx"])).sum() < 0.6:
verdict = "PLACEMENT STABLE: chest-centric search produces nearly the same optimal placement as body-centric. R6.2.3 is unnecessary at the placement-time level; chest-centric matters in the DSP pipeline (vital_signs.rs limb-mask), not the geometry."
elif chest_gain_pp > 10:
verdict = "CHEST-CENTRIC WINS: significant placement-strategy change. R6.2.3 should be a CLI option."
else:
verdict = "MIXED: chest and body placements differ but coverage gain is moderate. Documentation says use chest-centric for vital-signs cogs, body-centric for pose / count cogs."
print(f"VERDICT: {verdict}")
print()
out = {
"room": {"width_m": room_w, "height_m": room_h},
"freq_ghz": freq,
"body_zones": [{"name": n, "x": x0, "y": y0, "w": w, "h": h}
for n, x0, y0, w, h in body_zones],
"chest_zones": [{"name": n, "x": x0, "y": y0, "w": w, "h": h}
for n, x0, y0, w, h in chest_zones],
"best_body_centric": best_body,
"best_chest_centric": best_chest,
"cross_eval": {
"body_pl_on_chest": body_pl_on_chest["total_coverage_fraction"],
"chest_pl_on_body": chest_pl_on_body["total_coverage_fraction"],
"chest_gain_pp": chest_gain_pp,
"body_loss_pp": body_loss_pp,
},
"verdict": verdict,
}
Path(args.out).parent.mkdir(parents=True, exist_ok=True)
Path(args.out).write_text(json.dumps(out, indent=2))
print(f"Wrote {args.out}")
if __name__ == "__main__":
main()
@@ -0,0 +1,118 @@
{
"room": {
"width_m": 5.0,
"height_m": 5.0
},
"freq_ghz": 2.4,
"body_zones": [
{
"name": "bed",
"x": 1.5,
"y": 0.5,
"w": 2.0,
"h": 1.5
},
{
"name": "chair",
"x": 3.5,
"y": 3.5,
"w": 0.8,
"h": 0.8
},
{
"name": "desk",
"x": 0.2,
"y": 2.5,
"w": 1.0,
"h": 0.6
}
],
"chest_zones": [
{
"name": "bed_chest",
"x": 2.2,
"y": 0.8,
"w": 0.6,
"h": 0.4
},
{
"name": "chair_chest",
"x": 3.7,
"y": 3.7,
"w": 0.4,
"h": 0.4
},
{
"name": "desk_chest",
"x": 0.5,
"y": 2.7,
"w": 0.4,
"h": 0.2
}
],
"best_body_centric": {
"score": 0.493006993006993,
"tx": [
4.25,
0.0
],
"rx": [
0.0,
3.25
],
"link_m": 5.350233639758174,
"per_zone": {
"bed": {
"area_m2": 3.0000000000000004,
"covered_m2": 1.6175000000000004,
"coverage_fraction": 0.5391666666666667
},
"chair": {
"area_m2": 0.6400000000000001,
"covered_m2": 0.0,
"coverage_fraction": 0.0
},
"desk": {
"area_m2": 0.6500000000000001,
"covered_m2": 0.4975000000000001,
"coverage_fraction": 0.7653846153846153
}
}
},
"best_chest_centric": {
"score": 0.8235294117647058,
"tx": [
2.0,
0.0
],
"rx": [
4.5,
5.0
],
"link_m": 5.5901699437494745,
"per_zone": {
"bed_chest": {
"area_m2": 0.29250000000000004,
"covered_m2": 0.28750000000000003,
"coverage_fraction": 0.9829059829059829
},
"chair_chest": {
"area_m2": 0.20250000000000004,
"covered_m2": 0.20250000000000004,
"coverage_fraction": 1.0
},
"desk_chest": {
"area_m2": 0.10000000000000002,
"covered_m2": 0.0,
"coverage_fraction": 0.0
}
}
},
"cross_eval": {
"body_pl_on_chest": 0.5546218487394958,
"chest_pl_on_body": 0.40326340326340326,
"chest_gain_pp": 26.890756302521,
"body_loss_pp": 8.974358974358976
},
"verdict": "CHEST-CENTRIC WINS: significant placement-strategy change. R6.2.3 should be a CLI option."
}