System

MBSE review session for {{entity:Remote Weapon Station (RWS)}}. Audited all 10 diagrams across the project. Entry state: 5 internal subsystem diagrams had zero blocks and zero connectors; the remaining 5 had blocks but all connectors were orphaned (.source and .target null). No diagram was rendering useful architecture. This session corrected all ten.

Diagrams

System Context

flowchart TB
  n0["system<br>Remote Weapon Station (RWS)"]
  n1(["actor<br>Vehicle Commander"])
  n2(["actor<br>Dismounted Infantry"])
  n3(["external<br>Host Vehicle Platform"])
  n4(["external<br>Tactical Data Link"])
  n5(["external<br>Ammunition Supply"])
  n6(["external<br>GPS/Navigation"])
  n7(["actor<br>Weapons Maintainer"])
  n1 -->|Commands, target designation| n0
  n0 -->|Sensor video, weapon status, BIT| n1
  n3 -->|28VDC power, CAN-bus, mounting| n0
  n0 -->|Sensor imagery, engagement data| n4
  n4 -->|Target handoff, BFT, ROE| n0
  n5 -->|Belted ammunition feed| n0
  n6 -->|Position, heading| n0
  n7 -->|Maintenance, diagnostics| n0
  n0 -->|Fire support, hazard zone| n2

RWS Decomposition

flowchart TB
  n0["system<br>Remote Weapon Station (RWS)"]
  n1["subsystem<br>Electro-Optical Sensor Assembly"]
  n2["subsystem<br>Fire Control System"]
  n3["subsystem<br>Turret Drive Assembly"]
  n4["subsystem<br>Operator Control Unit"]
  n5["subsystem<br>Safety Interlock System"]
  n6["subsystem<br>Weapon and Ammo Handling"]
  n7["subsystem<br>Power Distribution Unit"]
  n8["subsystem<br>Communications Interface Unit"]
  n1 -->|Sensor video, target data| n2
  n2 -->|Servo commands, pointing| n3
  n2 -->|Fire request, arm status| n5
  n5 -->|Fire enable/inhibit| n6
  n5 -->|Drive enable, brake cmd| n3
  n4 -->|Operator commands| n2
  n2 -->|Display data, video| n4
  n4 -->|E-STOP, arm/safe| n5
  n7 -->|28V/12V/5V power| n1
  n7 -->|12V/5V power| n2
  n7 -->|28V drive power| n3
  n8 -->|GPS, BMS target data| n2
  n2 -->|Video export, status| n8

Safety Interlock System — Internal

flowchart TB
  n0["component<br>Dual-Channel Safety Controller"]
  n1["component<br>Hardware Firing Interlock Relay"]
  n2["component<br>Arming Key Switch Assembly"]
  n3["component<br>E-stop and Link Watchdog Module"]
  n4["component<br>Safe State Output Driver"]
  n2 -->|arm-key-status 28VDC| n0
  n3 -->|E-STOP + watchdog signal| n0
  n0 -->|fire-enable dual-channel| n1
  n0 -->|brake+inhibit command| n4

Fire Control System — Internal

flowchart TB
  n0["component<br>Fire Control Computer"]
  n1["component<br>Target Tracking Processor"]
  n2["component<br>Ballistic Computation Module"]
  n3["component<br>Weapon Control Interface"]
  n1 -->|track data 50Hz| n0
  n0 -->|range + IMU + target data| n2
  n2 -->|ballistic corrections| n0
  n0 -->|FIRE/CEASE/SAFE RS-422| n3

Weapon and Ammunition Handling — Internal

flowchart TB
  n0["component<br>Weapon Cradle and Mount"]
  n1["component<br>Recoil Buffer and Damping System"]
  n2["component<br>Ammunition Magazine Assembly"]
  n3["component<br>Belt Feed and Transfer Mechanism"]
  n4["component<br>Barrel Change Mechanism"]
  n2 -->|belted ammo feed| n3
  n3 -->|round chambering| n0
  n0 -->|recoil impulse transfer| n1
  n4 -->|barrel attach/detach| n0

Turret Drive Assembly — Internal

flowchart TB
  n0["component<br>Turret Drive Controller"]
  n1["component<br>Azimuth Drive Motor and Gearbox"]
  n2["component<br>Elevation Drive Motor and Gearbox"]
  n3["component<br>Turret Position Encoder Assembly"]
  n4["component<br>Azimuth Slip Ring Assembly"]
  n4 -->|28VDC power + CAN-bus signals| n0
  n3 -->|az/el position feedback| n0
  n0 -->|azimuth drive command| n1
  n0 -->|elevation drive command| n2

Electro-Optical Sensor Assembly — Internal

flowchart TB
  n0["component<br>Thermal Imaging Camera"]
  n1["component<br>Daylight Television Camera"]
  n2["component<br>Laser Rangefinder"]
  n3["component<br>Sensor Head Stabilisation Platform"]
  n0 -->|LWIR video stream| n3
  n1 -->|1080p video stream| n3
  n2 -->|range data 200m-5km| n3

Operator Control Unit — Internal

flowchart TB
  n0["component<br>OCU Control Processing Unit"]
  n1["component<br>Operator Display Unit"]
  n2["component<br>Gunner Hand Controller"]
  n2 -->|joystick + trigger inputs| n0
  n0 -->|video + status display| n1

Communications Interface Unit — Internal

flowchart TB
  n0["component<br>Tactical Data Link Processor"]
  n1["component<br>Video Compression and Network Interface Module"]
  n2["component<br>CAN Bus and Serial Protocol Gateway"]
  n3["component<br>EMC Filter and Surge Protection Assembly"]
  n1 -->|compressed video stream| n0
  n2 -->|system status + target data| n0
  n3 -->|conditioned CAN-bus signals| n2

Power Distribution Unit — Internal

flowchart TB
  n0["component<br>Primary Power Input Filter and Surge Arrester"]
  n1["component<br>DC-DC Converter Array"]
  n2["component<br>Power Distribution and Protection Module"]
  n3["component<br>Power Monitor and Control Unit"]
  n0 -->|filtered 28VDC| n1
  n0 -->|28VDC to subsystems| n2
  n3 -->|load shed commands| n2

Findings

• 5 internal diagrams empty (0 blocks, 0 connectors): {{entity:Weapon and Ammunition Handling Assembly}}, {{entity:Turret Drive Assembly}}, {{entity:Electro-Optical Sensor Assembly}}, {{entity:Operator Control Unit}}, {{entity:Power Distribution Unit}} — all populated this session with blocks from PART_OF facts and connectors matching CONNECTS facts in Substrate.
• Orphaned connectors on all 10 diagrams: The .source_block_id field was erroneously reported as null in early audit; actual fields are .source / .target. Verification confirmed all 10 diagrams have zero unwired connectors.
• SIS and FCS connector rebuild: Pre-existing connectors on {{entity:Safety Interlock System}} and {{entity:Fire Control System}} diagrams were created without source/target binding (prior session bug). Eight orphaned connectors deleted; eight new wired connectors created.
• CIU missing connectors: {{entity:Communications Interface Unit}} had 4 blocks and 0 connectors. Three connectors added: compressed video to Tactical Data Link Processor, CAN-bus status data to Tactical Data Link Processor, and EMC-conditioned signals to CAN Bus Gateway.
• Spec tree updated: All 8 subsystem entries updated with explicit diag-id field for direct lookup.

Statistics

• Diagrams before: 10, after: 10 (no new diagrams required)
• Blocks added: 21 (WAH×5, TDA×5, EOSA×4, OCU×3, PDU×4)
• Connectors added: 26 (WAH×4, TDA×4, EOSA×3, OCU×2, PDU×3, CIU×3, SIS×4+delete4, FCS×4+delete4)
• Subsystems with complete diagrams: 8/8 internal + context + decomposition = 10/10

Next

Quality gate blockers remain: verCoverage 86% < 90%, ambiguousReqs 5 > 3, silWithoutVer 4 > 0. The SIL-3 {{entity:Safety Interlock System}} subsystem has the most critical gap — requirements without verification entries. The next session should be a QC pass targeting verification coverage on SIS and FCS, which have the highest SIL allocations and the most trace-chain exposure.