{"abstract":"A tracker sitting just inside its stop hunts when the raw target is far outside the limits.","category":"Solar tracker geometry","checks":7,"contract":"Angles in millidegrees. The target is clamped to [lo, hi]. If |target - current| < deadband no move is made. Otherwise the move is limited to +-max_step, converted to whole motor steps of dps millidegrees truncated toward zero. Return [new position, signed steps].","evaluation_group":"w2-solar_tracker_geometry-actuator-step-command","failed_approach":"Skipping the deadband for out-of-range targets makes the actuator chatter at the stop.","family":"w2-solar_tracker_geometry-actuator-step-command-deadband-uses-clamped-target","id":"FA-93541","implementations":{"attempt":{"sha256":"7b5eec2eff8e4d04ad9da728574101283259df4bf6c64d773d777d016b16fa28","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(target, current, deadband, max_step, dps, lo, hi):\n    tgt = min(max(target, lo), hi)\n    err = tgt - current\n    if abs(err) < deadband and lo <= target <= hi:\n        return [current, 0]\n    move = max(-max_step, min(max_step, err))\n    steps = abs(move) // dps\n    if move < 0:\n        steps = -steps\n    return [current + steps * dps, steps]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-57417, -56117, 500, 2000, 300, -52000, 60000], [-54317, 6]],\n  ['control 2', [-62089, -29689, 500, 5000, 300, -55000, 60000], [-34489, -16]],\n  ['control 3', [-4975, 2618, 1000, 5000, 7, -55000, 60000], [-2380, -714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [48241, -7501, 500, 500, 125, -55000, 60000], [-7001, 4]],\n  ['control 2', [53151, 50604, 0, 5000, 7, -55000, 55000], [53145, 363]],\n  ['control 3', [54600, -48703, 1000, 2000, 125, -55000, 60000], [-46703, 16]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-63679, -20673, 250, 5000, 125, -52000, 60000], [-25673, -40]],\n  ['control 2', [13642, -49671, 1000, 5000, 7, -52000, 55000], [-44673, 714]],\n  ['control 3', [17787, -27002, 0, 5000, 125, -55000, 52000], [-22002, 40]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-66913, 56864, 250, 5000, 125, -52000, 52000], [51864, -40]],\n  ['control 2', [19310, -10964, 250, 5000, 125, -52000, 52000], [-5964, 40]],\n  ['control 3', [17837, -33972, 250, 5000, 7, -60000, 52000], [-28974, 714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [22704, 24328, 1000, 5000, 300, -60000, 55000], [22828, -5]],\n  ['control 2', [56539, -49336, 500, 2000, 7, -60000, 55000], [-47341, 285]],\n  ['control 3', [-50667, 12076, 1000, 2000, 125, -52000, 60000], [10076, -16]]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"6f6ae30487291e3ba6930559ee686fe3ea401d8d948c20e94aabd99ed9dff8eb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(target, current, deadband, max_step, dps, lo, hi):\n    tgt = min(max(target, lo), hi)\n    err = tgt - current\n    if abs(target - current) < deadband:\n        return [current, 0]\n    move = max(-max_step, min(max_step, err))\n    steps = abs(move) // dps\n    if move < 0:\n        steps = -steps\n    return [current + steps * dps, steps]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-57417, -56117, 500, 2000, 300, -52000, 60000], [-54317, 6]],\n  ['control 2', [-62089, -29689, 500, 5000, 300, -55000, 60000], [-34489, -16]],\n  ['control 3', [-4975, 2618, 1000, 5000, 7, -55000, 60000], [-2380, -714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [48241, -7501, 500, 500, 125, -55000, 60000], [-7001, 4]],\n  ['control 2', [53151, 50604, 0, 5000, 7, -55000, 55000], [53145, 363]],\n  ['control 3', [54600, -48703, 1000, 2000, 125, -55000, 60000], [-46703, 16]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-63679, -20673, 250, 5000, 125, -52000, 60000], [-25673, -40]],\n  ['control 2', [13642, -49671, 1000, 5000, 7, -52000, 55000], [-44673, 714]],\n  ['control 3', [17787, -27002, 0, 5000, 125, -55000, 52000], [-22002, 40]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-66913, 56864, 250, 5000, 125, -52000, 52000], [51864, -40]],\n  ['control 2', [19310, -10964, 250, 5000, 125, -52000, 52000], [-5964, 40]],\n  ['control 3', [17837, -33972, 250, 5000, 7, -60000, 52000], [-28974, 714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [22704, 24328, 1000, 5000, 300, -60000, 55000], [22828, -5]],\n  ['control 2', [56539, -49336, 500, 2000, 7, -60000, 55000], [-47341, 285]],\n  ['control 3', [-50667, 12076, 1000, 2000, 125, -52000, 60000], [10076, -16]]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"85c558e85a0d221f54d66f8a0e0ddda172911ed40454c3ea2838633d6e9a615e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(target, current, deadband, max_step, dps, lo, hi):\n    tgt = min(max(target, lo), hi)\n    err = tgt - current\n    if abs(err) < deadband:\n        return [current, 0]\n    move = max(-max_step, min(max_step, err))\n    steps = abs(move) // dps\n    if move < 0:\n        steps = -steps\n    return [current + steps * dps, steps]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-57417, -56117, 500, 2000, 300, -52000, 60000], [-54317, 6]],\n  ['control 2', [-62089, -29689, 500, 5000, 300, -55000, 60000], [-34489, -16]],\n  ['control 3', [-4975, 2618, 1000, 5000, 7, -55000, 60000], [-2380, -714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [48241, -7501, 500, 500, 125, -55000, 60000], [-7001, 4]],\n  ['control 2', [53151, 50604, 0, 5000, 7, -55000, 55000], [53145, 363]],\n  ['control 3', [54600, -48703, 1000, 2000, 125, -55000, 60000], [-46703, 16]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-63679, -20673, 250, 5000, 125, -52000, 60000], [-25673, -40]],\n  ['control 2', [13642, -49671, 1000, 5000, 7, -52000, 55000], [-44673, 714]],\n  ['control 3', [17787, -27002, 0, 5000, 125, -55000, 52000], [-22002, 40]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [-66913, 56864, 250, 5000, 125, -52000, 52000], [51864, -40]],\n  ['control 2', [19310, -10964, 250, 5000, 125, -52000, 52000], [-5964, 40]],\n  ['control 3', [17837, -33972, 250, 5000, 7, -60000, 52000], [-28974, 714]]],\n [['boundary: error equal to deadband', [1500, 1000, 500, 2000, 125, -60000, 60000], [1500, 4]],\n  ['boundary: target past west stop', [80000, 59000, 250, 5000, 7, -60000, 60000], [59994, 142]],\n  ['normal: negative move truncation', [-10000, 0, 250, 2000, 300, -60000, 60000], [-1800, -6]],\n  ['regression: far target while parked at stop', [80000, 59900, 500, 2000, 7, -60000, 60000],\n   [59900, 0]],\n  ['control 1', [22704, 24328, 1000, 5000, 300, -60000, 55000], [22828, -5]],\n  ['control 2', [56539, -49336, 500, 2000, 7, -60000, 55000], [-47341, 285]],\n  ['control 3', [-50667, 12076, 1000, 2000, 125, -52000, 60000], [10076, -16]]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-solar_tracker_geometry-actuator-step-command-deadband-uses-clamped-target","generated_at":"2026-09-29T14:51:56.152738+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"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.","repair":"Evaluate the deadband against the clamped target error.","root_cause":"The deadband is evaluated against the unclamped target.","sha256":"84fa77ca103252b57f3e1ee394f0504578ddc45663067b734ce9edd0b23aa11d","title":"Tracker actuator step command: deadband uses clamped target · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.659,"exit_code":1,"observations":[{"actual":[1500,4],"check":"boundary: error equal to deadband","expected":[1500,4],"passed":true},{"actual":[59994,142],"check":"boundary: target past west stop","expected":[59994,142],"passed":true},{"actual":[-1800,-6],"check":"normal: negative move truncation","expected":[-1800,-6],"passed":true},{"actual":[59998,14],"check":"regression: far target while parked at stop","expected":[59900,0],"passed":false},{"actual":[-54317,6],"check":"control 1","expected":[-54317,6],"passed":true},{"actual":[-34489,-16],"check":"control 2","expected":[-34489,-16],"passed":true},{"actual":[-2380,-714],"check":"control 3","expected":[-2380,-714],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: error equal to deadband\", \"actual\": [1500, 4], \"expected\": [1500, 4], \"passed\": true}, {\"check\": \"boundary: target past west stop\", \"actual\": [59994, 142], \"expected\": [59994, 142], \"passed\": true}, {\"check\": \"normal: negative move truncation\", \"actual\": [-1800, -6], \"expected\": [-1800, -6], \"passed\": true}, {\"check\": \"regression: far target while parked at stop\", \"actual\": [59998, 14], \"expected\": [59900, 0], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [-54317, 6], \"expected\": [-54317, 6], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [-34489, -16], \"expected\": [-34489, -16], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [-2380, -714], \"expected\": [-2380, -714], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.967,"exit_code":1,"observations":[{"actual":[1500,4],"check":"boundary: error equal to deadband","expected":[1500,4],"passed":true},{"actual":[59994,142],"check":"boundary: target past west stop","expected":[59994,142],"passed":true},{"actual":[-1800,-6],"check":"normal: negative move truncation","expected":[-1800,-6],"passed":true},{"actual":[59998,14],"check":"regression: far target while parked at stop","expected":[59900,0],"passed":false},{"actual":[-54317,6],"check":"control 1","expected":[-54317,6],"passed":true},{"actual":[-34489,-16],"check":"control 2","expected":[-34489,-16],"passed":true},{"actual":[-2380,-714],"check":"control 3","expected":[-2380,-714],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: error equal to deadband\", \"actual\": [1500, 4], \"expected\": [1500, 4], \"passed\": true}, {\"check\": \"boundary: target past west stop\", \"actual\": [59994, 142], \"expected\": [59994, 142], \"passed\": true}, {\"check\": \"normal: negative move truncation\", \"actual\": [-1800, -6], \"expected\": [-1800, -6], \"passed\": true}, {\"check\": \"regression: far target while parked at stop\", \"actual\": [59998, 14], \"expected\": [59900, 0], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [-54317, 6], \"expected\": [-54317, 6], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [-34489, -16], \"expected\": [-34489, -16], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [-2380, -714], \"expected\": [-2380, -714], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.322,"exit_code":0,"observations":[{"actual":[1500,4],"check":"boundary: error equal to deadband","expected":[1500,4],"passed":true},{"actual":[59994,142],"check":"boundary: target past west stop","expected":[59994,142],"passed":true},{"actual":[-1800,-6],"check":"normal: negative move truncation","expected":[-1800,-6],"passed":true},{"actual":[59900,0],"check":"regression: far target while parked at stop","expected":[59900,0],"passed":true},{"actual":[-54317,6],"check":"control 1","expected":[-54317,6],"passed":true},{"actual":[-34489,-16],"check":"control 2","expected":[-34489,-16],"passed":true},{"actual":[-2380,-714],"check":"control 3","expected":[-2380,-714],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: error equal to deadband\", \"actual\": [1500, 4], \"expected\": [1500, 4], \"passed\": true}, {\"check\": \"boundary: target past west stop\", \"actual\": [59994, 142], \"expected\": [59994, 142], \"passed\": true}, {\"check\": \"normal: negative move truncation\", \"actual\": [-1800, -6], \"expected\": [-1800, -6], \"passed\": true}, {\"check\": \"regression: far target while parked at stop\", \"actual\": [59900, 0], \"expected\": [59900, 0], \"passed\": true}, {\"check\": \"control 1\", \"actual\": [-54317, 6], \"expected\": [-54317, 6], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [-34489, -16], \"expected\": [-34489, -16], \"passed\": true}, {\"check\": \"control 3\", \"actual\": [-2380, -714], \"expected\": [-2380, -714], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}