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Reliability block diagram templates

RBD — Autonomous Vehicle Perception Chain

Five hundred operating hours of an AV safety chain: redundant supplies, a 2-of-3 sensor vote in which the camera slot is itself a pair, hot-standby perception compute and dual brake actuation.

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Autonomous vehicle perception and braking chainMission 500 h · 20.8 d · 11 blocks · 5 redundant arrangements · R 0.997499parallel · R 0.99996912 V vehicle supplyR 0.994460 · A 0.9999848 V redundant supplyR 0.994460 · A 0.999982 of 3 · R 0.999809parallel · R 0.999846Forward camera, primaryR 0.987578 · A 0.99990Forward camera, secondaryR 0.987578 · A 0.99990Long-range radarR 0.991701 · A 0.99993Roof lidarR 0.977529 · A 0.99964hot standby · switch 0.999 · R 0.999223Perception compute, primaryR 0.972604 · A 0.99967Perception compute, hot spareR 0.972604 · A 0.99967Planning and control stackR 0.998500parallel · R 0.999996Primary brake actuationR 0.998002 · A 0.99999Secondary brake actuationR 0.998002 · A 0.99999System reliability0.997499Unreliability0.0025System MTTF18 398 h · 2.10 yrAvailability1.000000Reliability importance — Birnbaum ∂R/∂Rᵢ, with criticality share1Planning and control stack0.998997crit 60%2Perception compute, primary0.028319crit 31%3Perception compute, hot spare0.027321crit 30%4Long-range radar0.022566crit 7.49%5Roof lidar0.008431crit 7.57%612 V vehicle supply0.005526crit 1.22%748 V redundant supply0.005526crit 1.22%8Primary brake actuation0.001993crit 0.16%+3 more blocks not shownThe availability figure of 1.000000 is computed over 10 of the 11 blocks in this arrangement. The other 1 state no `mttr:` and are fed in at availability 1 — perfectly available, for ever — so the number below is the availability of…Weakest link: Planning and control stack — R 0.998500, Birnbaum 0.998997, 60% of system failure. Improving this one block moves the system number further than improving any other.Redundancy check: removing any one of the 10 branches makes its own group measurably more likely to fail — the least of them by 3425%. Every one of them is earning its place.

Make it your own.

title "Autonomous vehicle perception and braking chain"
mission 500h                 # operating hours between depot checks

block power12 "12 V vehicle supply"           mtbf: 90000h  mttr: 2h
block power48 "48 V redundant supply"         mtbf: 90000h  mttr: 2h
block cam1    "Forward camera, primary"       mtbf: 40000h  mttr: 4h
block cam2    "Forward camera, secondary"     mtbf: 40000h  mttr: 4h
block radar   "Long-range radar"              mtbf: 60000h  mttr: 4h
block lidar   "Roof lidar"                    mtbf: 22000h  mttr: 8h
block fusion1 "Perception compute, primary"   mtbf: 18000h  mttr: 6h
block fusion2 "Perception compute, hot spare" mtbf: 18000h  mttr: 6h
block plan    "Planning and control stack"    r: 0.9985
block brakeP  "Primary brake actuation"       mtbf: 250000h mttr: 3h
block brakeS  "Secondary brake actuation"     mtbf: 250000h mttr: 3h

# The vote needs two of three sensing modalities; the camera modality is
# itself a redundant pair, which is where the third level of nesting comes in.
series {
  parallel { power12; power48 }
  kofn 2 of 3 {
    parallel { cam1; cam2 }
    radar
    lidar
  }
  standby hot { primary: fusion1; spare: fusion2; switch: 0.999 }
  plan
  parallel { brakeP; brakeS }
}