FA-93816 / Solar tracker geometry / Open access
Dawn and dusk parking positions: dusk parking side · case 01
At dusk the rows face east, away from the setting sun.
ROOT CAUSE
The dusk park angle has the wrong sign.
VERIFIED REPAIR
Park at +west_lim at dusk.
Unsuccessful approach: Using the east limit magnitude parks at the wrong angle on asymmetric trackers.
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: dusk parking side', [-20, 2, False, 5, 50, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 2, False, 3, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [70, 0, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-50, 0, False, 3, 55, 60], [60.0, 'dusk']],
['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: dusk parking side', [55, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [45, 0, False, 5, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [-50, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 3, False, 5, 45, 50], [50.0, 'dusk']],
['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: dusk parking side', [-70, 2, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [0, 2, False, 3, 50, 60], [60.0, 'dusk']],
['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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| 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'] | Failed |
| regression: dusk parking side | [-60.0, 'dusk'] | [60.0, 'dusk'] | Failed |
| regression: dusk parking side (partial repair) | [-60.0, 'dusk'] | [60.0, 'dusk'] | Failed |
| control 1 | [45.0, 'track'] | [45.0, 'track'] | Passed |
| control 2 | [50.0, 'track'] | [50.0, 'track'] | Passed |
SHA-256 / 47d972782f271da6e6982789d6f58e4c5b155a720d72d6dc83993c1d4d098e27
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 < 0:
return [0.0, 'night']
if sun_el < wake_el:
if am:
return [-float(east_lim), 'dawn']
return [float(east_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: dusk parking side', [-20, 2, False, 5, 50, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 2, False, 3, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [70, 0, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-50, 0, False, 3, 55, 60], [60.0, 'dusk']],
['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: dusk parking side', [55, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [45, 0, False, 5, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [-50, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 3, False, 5, 45, 50], [50.0, 'dusk']],
['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: dusk parking side', [-70, 2, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [0, 2, False, 3, 50, 60], [60.0, 'dusk']],
['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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| 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 | [50.0, 'dusk'] | [60.0, 'dusk'] | Failed |
| regression: dusk parking side | [50.0, 'dusk'] | [60.0, 'dusk'] | Failed |
| regression: dusk parking side (partial repair) | [45.0, 'dusk'] | [60.0, 'dusk'] | Failed |
| control 1 | [45.0, 'track'] | [45.0, 'track'] | Passed |
| control 2 | [50.0, 'track'] | [50.0, 'track'] | Passed |
SHA-256 / 87d7d2a1eb3f66bac43f3eebf13df2e68d5bde52ee070adfe3c4307920fa3f03
3 / The verified repair
Exit 0"""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: dusk parking side', [-20, 2, False, 5, 50, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 2, False, 3, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [70, 0, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-50, 0, False, 3, 55, 60], [60.0, 'dusk']],
['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: dusk parking side', [55, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [45, 0, False, 5, 45, 60], [60.0, 'dusk']],
['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: dusk parking side', [-50, 0, False, 3, 55, 50], [50.0, 'dusk']],
['regression: dusk parking side (partial repair)', [-20, 3, False, 5, 45, 50], [50.0, 'dusk']],
['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: dusk parking side', [-70, 2, False, 3, 45, 60], [60.0, 'dusk']],
['regression: dusk parking side (partial repair)', [0, 2, False, 3, 50, 60], [60.0, 'dusk']],
['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 fixture | Actual | Expected | Outcome |
|---|---|---|---|
| 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: dusk parking side | [60.0, 'dusk'] | [60.0, 'dusk'] | Passed |
| regression: dusk parking side (partial repair) | [60.0, 'dusk'] | [60.0, 'dusk'] | Passed |
| control 1 | [45.0, 'track'] | [45.0, 'track'] | Passed |
| control 2 | [50.0, 'track'] | [50.0, 'track'] | Passed |
SHA-256 / 177ca6d18c87f4ad23c346dd6a383f3cab8ad0e7d7800f9d7296dc013175d1f5
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 2026-09-29T14:51:58.706819+00:00.
Case digest / 2c6c4be8bfc00496649294c3413fbf9cad46dc5d4b979a1093d0328b6bf83f3b