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FA-93801 / Solar tracker geometry / Open access

Dawn and dusk parking positions: night boundary · case 01

At the moment of sunrise the tracker stays flat instead of parking toward the sun.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Elevation zero is classified as night.

THE FAILURE

Elevation zero is classified as night.

Unsuccessful approach: Extending night to -1 degree parks trackers while the sun is still below the horizon.

Case contract

sun_el < 0: [0.0, 'night']. 0 <= sun_el < wake_el: park facing the low sun, [-east_lim, 'dawn'] in the morning (am true) or [west_lim, 'dusk'] in the evening. Otherwise track the ideal angle clamped to the asymmetric limits [-east_lim, west_lim] ('track'). Angles are floats.

Why this case matters

Single-axis and dual-axis solar trackers turn a sun direction into actuator commands; a sign, frame or limit mistake points a whole plant away from the sun or into a mechanical stop.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(ideal, sun_el, am, wake_el, east_lim, west_lim):
    if sun_el <= 0:
        return [0.0, 'night']
    if sun_el < wake_el:
        if am:
            return [-float(east_lim), 'dawn']
        return [float(west_lim), 'dusk']
    return [float(max(-east_lim, min(west_lim, ideal))), 'track']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [70, 0, True, 3, 45, 50], [-45.0, 'dawn']],
  ['regression: night boundary (partial repair)', [70, -1, True, 3, 45, 60], [0.0, 'night']],
  ['control 1', [45, 5, False, 3, 45, 50], [45.0, 'track']],
  ['control 2', [55, 3, True, 3, 50, 50], [50.0, 'track']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [70, 0, False, 3, 45, 60], [60.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-70, -1, False, 3, 50, 60], [0.0, 'night']],
  ['control 1', [70, 5, False, 3, 50, 50], [50.0, 'track']],
  ['control 2', [0, -6, True, 3, 50, 60], [0.0, 'night']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [45, 0, True, 5, 45, 60], [-45.0, 'dawn']],
  ['regression: night boundary (partial repair)', [-20, -1, False, 3, 45, 50], [0.0, 'night']],
  ['control 1', [0, 8, True, 5, 55, 50], [0.0, 'track']],
  ['control 2', [-20, 0, False, 5, 55, 50], [50.0, 'dusk']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [-50, 0, False, 3, 55, 50], [50.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-20, -1, False, 3, 55, 50], [0.0, 'night']],
  ['control 1', [-20, 3, False, 3, 45, 50], [-20.0, 'track']],
  ['control 2', [45, -6, False, 5, 55, 60], [0.0, 'night']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [-20, 0, False, 5, 55, 60], [60.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-50, -1, False, 3, 55, 60], [0.0, 'night']],
  ['control 1', [55, 0, True, 5, 45, 60], [-45.0, 'dawn']],
  ['control 2', [-70, -6, True, 5, 55, 50], [0.0, 'night']]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
boundary: sun exactly on horizon[0.0, 'night'][-50.0, 'dawn']Failed
boundary: sun exactly at wake elevation[-50.0, 'track'][-50.0, 'track']Passed
normal: evening park[60.0, 'dusk'][60.0, 'dusk']Passed
regression: night boundary[0.0, 'night'][-45.0, 'dawn']Failed
regression: night boundary (partial repair)[0.0, 'night'][0.0, 'night']Passed
control 1[45.0, 'track'][45.0, 'track']Passed
control 2[50.0, 'track'][50.0, 'track']Passed

SHA-256 / 74c58c0fad2581ddc127d9d1f8e8b1a1c4ebe2bc34667e956ae6df93ccaeb92f

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(ideal, sun_el, am, wake_el, east_lim, west_lim):
    if sun_el < -1:
        return [0.0, 'night']
    if sun_el < wake_el:
        if am:
            return [-float(east_lim), 'dawn']
        return [float(west_lim), 'dusk']
    return [float(max(-east_lim, min(west_lim, ideal))), 'track']
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [70, 0, True, 3, 45, 50], [-45.0, 'dawn']],
  ['regression: night boundary (partial repair)', [70, -1, True, 3, 45, 60], [0.0, 'night']],
  ['control 1', [45, 5, False, 3, 45, 50], [45.0, 'track']],
  ['control 2', [55, 3, True, 3, 50, 50], [50.0, 'track']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [70, 0, False, 3, 45, 60], [60.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-70, -1, False, 3, 50, 60], [0.0, 'night']],
  ['control 1', [70, 5, False, 3, 50, 50], [50.0, 'track']],
  ['control 2', [0, -6, True, 3, 50, 60], [0.0, 'night']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [45, 0, True, 5, 45, 60], [-45.0, 'dawn']],
  ['regression: night boundary (partial repair)', [-20, -1, False, 3, 45, 50], [0.0, 'night']],
  ['control 1', [0, 8, True, 5, 55, 50], [0.0, 'track']],
  ['control 2', [-20, 0, False, 5, 55, 50], [50.0, 'dusk']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [-50, 0, False, 3, 55, 50], [50.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-20, -1, False, 3, 55, 50], [0.0, 'night']],
  ['control 1', [-20, 3, False, 3, 45, 50], [-20.0, 'track']],
  ['control 2', [45, -6, False, 5, 55, 60], [0.0, 'night']]],
 [['boundary: sun exactly on horizon', [-70, 0, True, 5, 50, 60], [-50.0, 'dawn']],
  ['boundary: sun exactly at wake elevation', [-50, 5, True, 5, 50, 60], [-50.0, 'track']],
  ['normal: evening park', [55, 2, False, 5, 50, 60], [60.0, 'dusk']],
  ['regression: night boundary', [-20, 0, False, 5, 55, 60], [60.0, 'dusk']],
  ['regression: night boundary (partial repair)', [-50, -1, False, 3, 55, 60], [0.0, 'night']],
  ['control 1', [55, 0, True, 5, 45, 60], [-45.0, 'dawn']],
  ['control 2', [-70, -6, True, 5, 55, 50], [0.0, 'night']]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
boundary: sun exactly on horizon[-50.0, 'dawn'][-50.0, 'dawn']Passed
boundary: sun exactly at wake elevation[-50.0, 'track'][-50.0, 'track']Passed
normal: evening park[60.0, 'dusk'][60.0, 'dusk']Passed
regression: night boundary[-45.0, 'dawn'][-45.0, 'dawn']Passed
regression: night boundary (partial repair)[-45.0, 'dawn'][0.0, 'night']Failed
control 1[45.0, 'track'][45.0, 'track']Passed
control 2[50.0, 'track'][50.0, 'track']Passed

SHA-256 / 0e08ff0624f05d8a2a69951b96c9c3cf9ad3cf3b9101732e235d1614bffcf516

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

Deterministic stipulated toy contract for teaching; no claim of conformance with any standard, vendor protocol or production controller. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:51:58.443141+00:00.

Case digest / fa8705c80a78fb8c6047031d26861b6c71deced07151f9ade8cf8a60209d7a75