RCI 052 · System-topology field note

Nine nodes, ten relations, two IMU paths—one at a time.

The Berkeley Humanoid Lite profile maps host, USB fan-out, four CAN transports, two actuator banks and a protected power tree. It also keeps a boundary many readers skip: the live documentation is an observation layer, not the pinned v1.1.0 release.

Published 2026-08-185 min readRobot System Index v0.8.21

What is now public

The Berkeley Humanoid Lite deep profile audits 52 selected rows from the public BOM sheet—26 Humanoid rows plus 13 rows in each actuator tab—and now carries a nine-node, ten-relation system map built from the official documentation. The ten relations cover the host-to-hub USB surface, the hub-to-adapter fan-out, 1 Mbit/s CAN control and feedback to each actuator bank, the two alternative IMU paths, and four power relations: main-bus feeds to each actuator bank, the protected feed into the named conversion and monitoring surface, and the low-voltage path to the on-board computer.

Every relation restates responsibility-party statements at an identified revision, keeps its unresolved list and carries a physical-validation state of none. The machine layers are robots.json and the interface-relation CSV; the documentation-versus-release separation and the US/China procurement-column boundary are recorded relations in the lifecycle CSV.

The nine nodes

NodeKindSelected boundary
On-board NUC / Mini PC boundaryComputeCurrent guide identifies a BeeLink N95-class NUC on Ubuntu 22.04; the live BOM row stays generic “Mini PC”
Two generic USB hubsControlHub models, port counts and upstream/downstream assignment unpublished
Four USB-CAN adaptersControlTwo arms and two legs expected as Linux ports can0–can3; adapter identity and port mapping not frozen
M6C12 actuator bankActuationTen positions: eight leg and two arm, with per-module B-G431B-ESC1 and AS5600 boundaries
5010 actuator bankActuationTwelve positions: four leg and eight arm, with per-module B-G431B-ESC1 and AS5600 boundaries
Original BNO085 + Arduino Nano IMU pathPerceptionIMU reaches the host through an Arduino Nano; alternative to IM10A, not additional
Recommended IM10A direct-USB IMU pathPerceptionRecommended for its direct USB connection; marked as the alternative option in the live BOM
6S LiPo, breaker and main power busPowerGeneric 6S pack and circuit breaker feeding an XT60 trunk with XT30 actuator branches
24→12 V / 12→5 V conversion and monitoringPowerOne converter per named transition plus voltage and current monitors; ratings and rail allocation unpublished

The two IMU nodes are alternatives, not a dual-IMU design. The original path routes a BNO085 through an Arduino Nano to the computer; the currently recommended path is an IM10A connected directly over USB. Absent one as-built selection, the profile refuses to count both as simultaneously installed.

Live documentation is not the frozen BOM

The platform's release v1.1.0 is a tagged, dated boundary. The BOM, however, lives in a public spreadsheet and GitBook documentation that can change without changing the release tag—rows, links, formulas and recommendations included. No immutable public sheet revision is cryptographically bound to v1.1.0, so the profile treats the live surfaces as an observation layer with observation dates, kept separate from the release. This is also why the compute node carries two identities at once: the current guide names a BeeLink N95-class NUC while the live BOM row remains generic.

Label rule

The converter row named “24 V” is a product label at a named voltage transition. It is not a measured 6S pack voltage, and RCI has not applied power to any rail.

What this is not

  • Not an as-built inventory. No serialised robot, module set, CAN ID map, calibration record or harness is bound to the map.
  • Not a compatibility or performance claim. Actuator position counts are published configuration quantities, not RCI-verified installed banks or torque results.
  • Zero RCI physical tests. No USB tree enumeration, CAN frame capture, IMU stream or power measurement exists.
  • Open unknowns stay open: hub-to-adapter pairing, limb-to-port mapping, adapter and converter models, pack identity, breaker behavior, shunt placement and the host's exact supply rail are all unpublished in the selected surfaces.

Corrections

If a node boundary, relation, count or the release-separation reading above is wrong, use the corrections process. Corrections are logged; prior states are not erased.