System

{{entity:Surgical Robot System}} — teleoperated minimally invasive surgical system. This is the fifth decomposition session. Three subsystems were fully decomposed in previous sessions: {{entity:Vision and Imaging System}}, {{entity:Motion Control System}}, and {{entity:Safety and Interlock Subsystem}}. This session tackles the two remaining subsystems with the strongest architectural coupling and safety criticality: {{entity:Haptic Feedback Subsystem}} and {{entity:Communication and Data Management System}}.

Decomposition

Haptic Feedback Subsystem was broken into four components: {{entity:Force Sensing Module}} ({{hex:D4C51008}}), {{entity:Force Signal Conditioner}} ({{hex:D4A51018}}), {{entity:Haptic Controller}} ({{hex:54FD7208}}), and {{entity:Master Handle Actuator}} ({{hex:D7F51008}}). The key architectural decision was placing the galvanic isolation barrier at the Force Signal Conditioner PCB boundary rather than at the instrument tip. This keeps the patient-contact chain entirely passive (strain gauge bridge) and confines the IEC 60601-1 leakage current isolation requirement to a single testable component.

flowchart TB
  FSM["Force Sensing Module"]
  FSC["Force Signal Conditioner"]
  HC["Haptic Controller"]
  MHA["Master Handle Actuator"]
  FSM -->|strain gauge signals| FSC
  FSC -->|SPI 16-bit force data| HC
  HC -->|CAN FD torque setpoints| MHA

Communication and Data Management System was broken into four components: {{entity:Inter-Cart Fibre Link}} ({{hex:C6855008}}), {{entity:Real-Time Protocol Engine}} ({{hex:51F77208}}), {{entity:Procedure Data Recorder}} ({{hex:50851208}}), and {{entity:Network Management Controller}} ({{hex:51B73818}}). The FPGA-based protocol engine rather than a Linux network stack was the decisive architectural choice, providing hardware-guaranteed timing isolation between safety, kinematic, and video traffic channels.

Analysis

The {{hex:54FD7208}} classification for the Haptic Controller — showing strong signal-processing and active traits — accurately reflects its dual role as a safety monitor and a real-time servo-loop closure device. The {{hex:51B73818}} hex for the Network Management Controller shares significant trait overlap with the {{entity:Communication Monitor}} safety component ({{hex:55B77A18}}), a cross-domain echo: both implement passive observation and fault-detection roles over a communication channel. The distinction in hex codes reflects the NMC’s physical layer focus versus the Communication Monitor’s application-layer framing checks.

Lint reported one high finding: {{entity:Surgical Illumination Source}} lacks the Physical Object trait despite having physical installation requirements. This is acknowledged as a classification artefact from the subsystem-level description; the LED light source is unambiguously a physical device. A clarifying architecture note was added. The 26 “lacks SHALL keyword” low findings all affect Architecture Decision and Verification entries, which use narrative and “Verify” syntax by design — acknowledged.

Requirements

Five {{sub:SUB-MAIN-022}}–{{sub:SUB-MAIN-026}} requirements were written for the Haptic subsystem. The force measurement resolution of 0.05N is derived from the human haptic discrimination threshold (approx. 0.1N), with the sensor required to resolve at half that value to avoid perceptible quantisation in delicate tissue contact. The 1N master feedback limit ({{sub:SUB-MAIN-024}}) derives from IEC 80601-2-77 guidance and applies in sensor-fault conditions as well as normal operation, requiring a hardware-layer enforcement path independent of the Haptic Controller software.

For Communications, four {{sub:SUB-MAIN-027}}–{{sub:SUB-MAIN-030}} requirements cover 1ms latency budget, 10ms fibre failover with zero-frame-loss, 8-hour WORM recording, and frame-level error recovery. The failover timing ({{sub:SUB-MAIN-028}}) is derived from the Motion Controller’s 100ms safe-coast interval: 10ms is one-tenth of that window, providing margin before the Safety and Interlock Subsystem declares a comms fault.

Three interface requirements were created for haptic ({{ifc:IFC-MAIN-015}}–{{ifc:IFC-MAIN-017}}) and two for communications ({{ifc:IFC-MAIN-018}}–{{ifc:IFC-MAIN-019}}). Architecture decisions {{sub:ARC-MAIN-004}} and {{sub:ARC-MAIN-005}} record the isolation placement and FPGA protocol choices respectively. Orphan trace gaps from sessions 340 and 341 ({{sub:SUB-MAIN-008}}, {{sub:SUB-MAIN-009}}, {{sub:SUB-MAIN-015}}, {{ifc:IFC-MAIN-006}}, {{ifc:IFC-MAIN-008}}) were closed this session. VER/IFC coverage is now 21/19.

Next

Remaining undecomposed subsystems: Energy Delivery System (electrosurgery RF, bipolar, safety isolation), Power Management Subsystem (3-phase input, UPS, regulated rails), and Surgical Instrument System (EndoWrist instruments, IDU, sterilisation interfaces). The Energy Delivery System carries the highest safety risk due to RF leakage current and simultaneous active instrument hazards — it should be prioritised in the next session. After these three, the system will be ready for first-pass completion assessment and QC handoff.