Files
forgefirm/scripts/bench/flow_recheck_char.py
T
ScottW514 cc927aca5f Add laser-safety and regulatory documentation; scrub bench identity
- LIGHTBURN.md: mandatory "Before you cut" safety section; the
  walkthrough now reflects the firing machine (dry runs need the
  layer output off or M5; live first-cut instructions); the homing
  entry documents homing_mode and the gfcloud method; the machine
  address is a placeholder.
- README.md: condensed safety section linking the full text and the
  regulatory notes.
- INSTALL.md: "Regulatory and legal" section ahead of the install
  steps; routine updates route through the panel updater rather than
  the installer.
- BRINGUP.md: the release signing key is described as held offline
  (no on-disk path); bench address and credential notes removed;
  Next-work item 7 corrected (the installer embeds the production
  release key); status entry for audit remediation Phases 0-1; the
  GATE A kernel drills join the pending image-flash checklist.
- bench scripts: the target host comes from GF_HOST (or argv) instead
  of a hardcoded address.
- laser_stream_test.py: per-session controller runs with a hermetic
  cooling-verdict publisher; new assertions that every stream
  terminates with FIRE clear (including M3 held to stream end) and
  that no FIRE bit rides a zero-step gap; a cycle-churn session
  exercises the stop/start seams.

Audit findings D-1, D-2, D-3, D-5, D-10, D-12, B-10, and the harness
half of D-4/G-1.
2026-08-14 15:38:24 -04:00

114 lines
4.3 KiB
Python

#!/usr/bin/env python3
"""Characterize a SHORT periodic flow re-check for use DURING a job.
Why a separate design from the job-start check: with the laser firing
and coolant flowing, tube heat raises BOTH sensors, inflating a plain
downstream-rise metric toward a false fault. With the pump stopped that
heat never reaches the sensors at all (stagnant loop), so the no-flow
signature stays at its idle value. The two signatures therefore
converge during a cut. The differential rise
(downstream_end - downstream_start) - (upstream_end - upstream_start)
cancels that common-mode heating and is the metric this measures.
TWO DEAD ENDS, recorded so they are not re-invented:
1. Absolute over-temperature does NOT detect a failed pump. The
sensors read the water at their own location; with no circulation
the tube's heat stays in the tube and never reaches them. The loop
can read perfectly comfortable while the tube cooks. Over-temp
monitoring detects a hot CIRCULATING loop - a different failure.
2. "The coolant should warm up while cutting" is NOT a usable
indicator either. A low-duty engrave (say 5% duty at 30% power) can
put so little heat in that the cooling system absorbs it with no
measurable rise, so a flat trend is equally consistent with a light
load working correctly and with a dead pump. Ambiguous evidence is
worse than none - it invites false confidence.
Hence: periodic ACTIVE interrogation with the heater, which creates a
known stimulus instead of waiting for one, is the only valid method on
this hardware (there is no pump tach or pump current sense anywhere in
the machine).
Usage: flow_recheck_char.py [heater_pct] [window_s] (default 50 30)
Runs both flow and no-flow cases from a comparable loop state and
prints the differential separation. Aborts if downstream passes 45 C.
"""
import math
import os
import subprocess
import sys
import time
HOST = os.environ.get('GF_HOST')
if not HOST:
raise SystemExit('set GF_HOST to the machine IP address')
F = 1024.0 * 1.3
RD, BETA = 10000.0, 3380.0
RINF = 10000.0 * math.exp(-3380.0 / 298.15)
DOWN_ABORT_C = 45.0
def degc(raw):
r = RD / (F / raw - 1.0)
return BETA / math.log(r / RINF) - 273.15
def board(cmd):
r = subprocess.run(['wsl', '-d', 'forge-yocto', '--', 'ssh',
'-o', 'PreferredAuthentications=none',
'root@' + HOST, cmd],
capture_output=True, text=True, timeout=30)
return r.stdout.strip()
def sample():
o = board('cat /sys/glowforge/pic/water_temp_1 /sys/glowforge/pic/water_temp_2').split()
return degc(int(o[0])), degc(int(o[1]))
def settle(seconds=100):
board('echo 1 > /sys/glowforge/thermal/water_pump_on; echo 0 > /sys/glowforge/thermal/heater_pwm')
time.sleep(seconds)
def check(tag, pump_on, pct, window):
board('echo %d > /sys/glowforge/thermal/water_pump_on' % (1 if pump_on else 0))
time.sleep(2)
d0, u0 = sample()
board('echo %d > /sys/glowforge/thermal/heater_pwm' % int(65535 * pct / 100))
t0 = time.time()
d, u = d0, u0
while time.time() - t0 < window:
time.sleep(5)
d, u = sample()
print(' %-8s t=%2.0fs down=%5.2f (%+5.2f) up=%5.2f (%+5.2f) diff=%+5.2f'
% (tag, time.time() - t0, d, d - d0, u, u - u0, (d - d0) - (u - u0)), flush=True)
if d >= DOWN_ABORT_C:
print(' abort: downstream at safety limit', flush=True)
break
board('echo 0 > /sys/glowforge/thermal/heater_pwm; echo 1 > /sys/glowforge/thermal/water_pump_on')
return (d - d0) - (u - u0), d - d0
pct = int(sys.argv[1]) if len(sys.argv) > 1 else 50
window = int(sys.argv[2]) if len(sys.argv) > 2 else 30
print('=== periodic re-check characterization: %d%% heater, %d s window' % (pct, window))
settle()
print(' flow case:')
flow_diff, flow_rise = check('flow', True, pct, window)
settle()
print(' no-flow case:')
noflow_diff, noflow_rise = check('noflow', False, pct, window)
settle(60)
print()
print('differential rise: flow %+.2f no-flow %+.2f separation %.2f C'
% (flow_diff, noflow_diff, noflow_diff - flow_diff))
print('plain down rise: flow %+.2f no-flow %+.2f separation %.2f C'
% (flow_rise, noflow_rise, noflow_rise - flow_rise))
print('suggested differential threshold: %.2f C' % ((flow_diff + noflow_diff) / 2))