{"abstract":"An error exactly equal to the deadband is never corrected.","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":"Dropping abs() suppresses every negative correction.","family":"w2-solar_tracker_geometry-actuator-step-command-deadband-comparison","id":"FA-93521","implementations":{"attempt":{"sha256":"5ca42cb4533087a66342998b6d72c877b62ecb93ac994a7be4d2c9cbaf237e0b","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 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: deadband comparison (partial repair)', [87, 3902, 250, 500, 90, -52000, 55000],\n   [3452, -5]],\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: deadband comparison (partial repair)', [-54271, -9833, 0, 2000, 90, -52000, 52000],\n   [-11813, -22]],\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: deadband comparison (partial repair)', [25571, 48224, 500, 2000, 90, -52000, 55000],\n   [46244, -22]],\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: deadband comparison (partial repair)',\n   [-50922, -33896, 1000, 2000, 7, -52000, 60000], [-35891, -285]],\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: deadband comparison (partial repair)', [3491, 18980, 250, 2000, 7, -55000, 60000],\n   [16985, -285]],\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":"715e9b89d0df21161c55385a8645832868cc8290839590c15c1feb53db53e89a","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: deadband comparison (partial repair)', [87, 3902, 250, 500, 90, -52000, 55000],\n   [3452, -5]],\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: deadband comparison (partial repair)', [-54271, -9833, 0, 2000, 90, -52000, 52000],\n   [-11813, -22]],\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: deadband comparison (partial repair)', [25571, 48224, 500, 2000, 90, -52000, 55000],\n   [46244, -22]],\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: deadband comparison (partial repair)',\n   [-50922, -33896, 1000, 2000, 7, -52000, 60000], [-35891, -285]],\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: deadband comparison (partial repair)', [3491, 18980, 250, 2000, 7, -55000, 60000],\n   [16985, -285]],\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":"efacd31a81438fa8d07be32334b59b8a9f193e4c25b7a410769cc559d3d09745","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: deadband comparison (partial repair)', [87, 3902, 250, 500, 90, -52000, 55000],\n   [3452, -5]],\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: deadband comparison (partial repair)', [-54271, -9833, 0, 2000, 90, -52000, 52000],\n   [-11813, -22]],\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: deadband comparison (partial repair)', [25571, 48224, 500, 2000, 90, -52000, 55000],\n   [46244, -22]],\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: deadband comparison (partial repair)',\n   [-50922, -33896, 1000, 2000, 7, -52000, 60000], [-35891, -285]],\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: deadband comparison (partial repair)', [3491, 18980, 250, 2000, 7, -55000, 60000],\n   [16985, -285]],\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-comparison","generated_at":"2026-09-29T14:51:55.907492+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":"Move when |err| >= deadband.","root_cause":"The deadband test is inclusive.","sha256":"31a7f95451aa674dc51e4fcc978dbcb38b78183a22567668a4e6f57c0aea9935","title":"Tracker actuator step command: deadband comparison · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":42.888,"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":[0,0],"check":"normal: negative move truncation","expected":[-1800,-6],"passed":false},{"actual":[3902,0],"check":"regression: deadband comparison (partial repair)","expected":[3452,-5],"passed":false},{"actual":[-54317,6],"check":"control 1","expected":[-54317,6],"passed":true},{"actual":[-29689,0],"check":"control 2","expected":[-34489,-16],"passed":false},{"actual":[2618,0],"check":"control 3","expected":[-2380,-714],"passed":false}],"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\": [0, 0], \"expected\": [-1800, -6], \"passed\": false}, {\"check\": \"regression: deadband comparison (partial repair)\", \"actual\": [3902, 0], \"expected\": [3452, -5], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [-54317, 6], \"expected\": [-54317, 6], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [-29689, 0], \"expected\": [-34489, -16], \"passed\": false}, {\"check\": \"control 3\", \"actual\": [2618, 0], \"expected\": [-2380, -714], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.813,"exit_code":1,"observations":[{"actual":[1000,0],"check":"boundary: error equal to deadband","expected":[1500,4],"passed":false},{"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":[3452,-5],"check":"regression: deadband comparison (partial repair)","expected":[3452,-5],"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":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: error equal to deadband\", \"actual\": [1000, 0], \"expected\": [1500, 4], \"passed\": false}, {\"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: deadband comparison (partial repair)\", \"actual\": [3452, -5], \"expected\": [3452, -5], \"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\": false}\n"},"fixed":{"elapsed_ms":44.93,"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":[3452,-5],"check":"regression: deadband comparison (partial repair)","expected":[3452,-5],"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: deadband comparison (partial repair)\", \"actual\": [3452, -5], \"expected\": [3452, -5], \"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"}