class GoWrong(Tree):
spec = P('misunderstanding\nabout MR14', failure_rate=1e-4)
check = P('not discovered during\npeer review', failure_rate=1e-4)
failure = T(
r'moving to the \"gathered position\"\ninstead of \"towards the victim\"'
)
failure << (spec & check)
class EscortNoLED(Tree):
led = P('primary indicator LED failure', failure_rate=1e-5)
with F('not aware of escorting') as not_aware:
not_aware << (hw.EPuck.memory_fault() | Escort.unintentional)
failure = T('escorting, but\nno LED indication')
failure << (led | not_aware | software_bug())
class NoEscort(Tree):
indirect = F('taking a detour during escort')
indirect << (Uncooperative.failure.as_leaf() | hw.Motor.failure()
| hw.EPuck.memory_fault())
failure = T(
'not moving the victim out;\nat least not on shortest known path')
failure << (StandingStill.failure | Escort.unintentional.as_leaf()
| indirect)
class SeeNoLed(Tree):
primary = P('primary failure\nof the display-LED', failure_rate=1e-5)
software = software_bug()
not_turned_on = hw.EPuck.not_turned_on()
failure = T('clear line of sight,\nbut no LED indication')
failure << (VictimSilent.failure | proto.SOS.receiver | primary | software
| not_turned_on)
class SpuriousMovements(Tree):
turn = F('does not\nstop turning\nwhile sensing\nangle to victim')
turn << (VictimSilent.failure.as_leaf() | hw.ExtBoard.failure)
badcolor = S("Tin Bot's physical color\nis not hardcoded color")
failure = T('spurious movements\n(e.g., spin around, drive circles, ...)')
failure << (proto.LPS.failure.as_leaf() | software_bug() | badcolor
| Proximity.failure() | Uncooperative.failure.as_leaf() | turn)
class SystemFailure(Tree):
tin_bot_failure = F('Tin Bot failure\n')
tin_bot_failure << (VictimLost.failure | IgnoreVictim.failure
| NoEscort.failure | Victim404.failure)
all_bad = F('all Tin Bots fail')
all_bad << (tin_bot_failure & tin_bot_failure.as_leaf())
failure = T('system failure\n(victim remains in maze)')
failure << all_bad
class Uncooperative(Tree):
with F('sender failure') as sender:
sender << (software_bug() | hw.Bluetooth.sender())
with F('receiver failure') as receiver:
receiver << (software_bug() | hw.Bluetooth.receiver())
design = P('protocol design failure (T2T)', failure_rate=0)
failure = T('uncooperative behavior\n(explores cells twice, ...)')
failure << (sender | receiver | hw.Bluetooth.medium() | design)
class StandingStill(Tree):
with F('no initial position from LPS') as no_initial_lps:
user = S('user did not\nenable LPS')
no_initial_lps << (proto.LPS.failure | user)
with F('wheels do not turn') as wheel_fault:
blocked = S('wheels blocked')
wheel_fault << (hw.Motor.failure | blocked)
bad_setup = S('bad setup')
software = software_bug()
failure = T('standing still')
failure << (no_initial_lps | bad_setup | software | wheel_fault
| hw.EPuck.failure | RunIntoWall.failure | Escort.hang)
class VictimLost(Tree):
with F('victim dropped / unable to grab') as dropped:
magnet_weak = P('primary magnet failure\n(e.g., too weak)', 1e-5)
belt_weak = P('primary belt failure\n(magnet slips out of the belt)',
1e-1)
# Your magnet is weak, your belt is weak, your bloodline is
# weak, and you will *not* survive winter!
dropped << (belt_weak | magnet_weak)
pulled_away = F('pulled away by\nanother Tin Bot')
pulled_away << (Escort.unintentional | Uncooperative.failure.as_leaf())
failure = T('victim lost while escorting')
failure << (pulled_away | dropped)
class IgnoreVictim(Tree):
conflict = F('conflicting data\nabout victim')
conflict << (hw.EPuck.memory_fault() | S('user moved\nvictim')
| Uncooperative.failure.as_leaf())
late = P('too high min-distance\nfor sensing again', failure_rate=1e-4)
no_triang = F('triangulation fails')
no_triang << (late | software_bug())
overwrite = F('information gets overwritten\nbefore E-Puck picks it up')
overwrite << Uncooperative.design()
failure = T('not using information\nabout victim')
failure << (hw.ExtBoard.failure.as_leaf() | conflict | no_triang
| overwrite)
class Victim404(Tree):
not_placed_in = S('user did not place\nthe victim in the maze')
unsolvable = S('unsolvable maze')
rhr_hangs = F('right-hand follower\ndrives in circles')
rhr_hangs << (P('right-hand follower\ncan drive in circles',
failure_rate=inf) & P('path-pruning fails', failure_rate=0)
& S('maze is not\n1-outerplanar'))
drift = F('lost orientation')
drift << (proto.LPS.failure
& P('approximation algorithm\nis way off', failure_rate=1e-3)
& P('drift from real orientation\ndoes not stabilize',
failure_rate=1e-5))
failure = T('victim cannot be found')
failure << (VictimSilent.failure | proto.SOS.receiver() | rhr_hangs | drift
| not_placed_in | unsolvable)
class RunIntoWall(Tree):
failure = T('run into walls')
failure << (Proximity.collision | bad_firmware)
class NoPowerLED(Tree):
primary = P('primary power LED failure', failure_rate=1e-5)
failure = T('power LED is off')
failure << (primary | hw.EPuck.failure)
class VictimSilent(Tree):
software = software_bug()
failure = T('victim\'s LED does not\nsend valid signal')
failure << (software | hw.Victim.failure)