Project Getting Started

Worked for 1 min 37 sec

I reviewed the completed research handoffs and checked the live schematic and PCB. This revision is still incomplete and remains on release hold—not an approved battery-powered design.

Completed

Preserved the pre-change backup.
Recorded your CNHL 3S battery requirements and researched battery monitoring, default-off protection, auxiliary supplies and a purchased motor converter.
Documented integration gaps and saved the verified continuation state in the revision handoff.

What remains unresolved

Motor power: no battery-protection or high-current motor-power circuit was added. The proposed TRACO converter is not selected or approved: exact-model capability and low-input thermal derating remain unconfirmed. FET/shunt sizing, fuse coordination, current limits, regeneration handling, harness losses and transient/thermal validation are unfinished. The 25–30 A option remains provisional capacity—not continuous demand—and D24V150F5 remains unsuitable for unrestricted 25–30 A service.
Face: still disabled. U4’s head-side supply remains unsourced, and EN remains pulled low.
C7/C8/C13: still generic capacitors without exact qualified MPNs; effective-capacitance/ESR qualification is unfinished.
Integration: firmware compatibility, audio tests, exact harness drawings and mechanical fit remain incomplete. The PCB is still the unapproved 160 × 100 mm placeholder.
Checks: the eight ERC categories returned by my inspection passed, but this was not a complete final sign-off. DRC still reports unrouted connections. No manufacturing files were released.

What I still need from you

Original/restored torso and head CAD, including mounting locations and cable-clearance requirements.
Photos of the received battery label and balance connector; installed harness lengths and cooling conditions.
Where not already supplied: exact head/display and Jetson-carrier revisions, plus the target firmware repository and commit. Joint duty/torque requirements are also needed if reduced-current operation is acceptable.

You do not need to resend the motor model or battery product identity. Execution stopped because your account ran out of ACUs.

Waiting for input

Files

Schematic

Layout

3D View

Preliminary FMEA

Motor power hazard gate — 2026-10-22

RELEASE HOLD. @power-budget~c0 supersedes earlier motor sizing assumptions with a30A/150W PROVISIONAL capability envelope,22.05A nominal-stall reference and source-backed FAIL/UNVERIFIED ledger. Greater source capacity increases available fault energy; motor firmware limits, converter OCP and torque-off are not coordinated branch protection or independent power cutoff. D24V150F5 is not a25–30A source. EH two-motor2.94A chain has essentially no3A catalog margin; generic crimp AWG22 maximum conflicts with ROBOTIS21AWG cable description and needs exact approved assembly evidence. Require protected external star feed/return, evidence-based branches, default-off latched motor disconnect and retained regen absorption; all remain unimplemented. Budget validation matrix requires full battery/BMS, harness, thermal/CAD and torque/duty inputs, USB-on cutoff/backfeed and fault-selectivity tests. No hazard is closed by this analysis and no RPN is reduced without evidence.

Scope

This is a design-stage failure mode analysis based on the current schematic architecture. It will be refined as the design matures through layout and prototyping. Review-stage estimates below are prioritization judgments, not measured probabilities or a safety certification. Independent architecture/circuit review informed the mitigations.

Failure Mode Table

Table

Component/Subsystem	Failure Mode	Effect on System	Severity (1-10)	Likelihood (1-10)	Detection (1-10)	RPN	Mitigation
Future LiPo power path	Short/reverse battery/no coordinated fuse	Fire/burns and board destruction	10	5	7	350	Do not connect battery; source pack/fault data and design protection
Future per-cell monitor	Weak cell/open balance tap	Overdischarge, damage or lost power	9	5	8	360	Protected filtered taps/open-wire diagnostics; early motor shedding, critical cutoff
Motor cutoff	Stuck-on switch/lost watchdog	Uncontrolled torque	10	4	8	320	Independent normally-off high-side disconnect, fault latch, deliberate rearm and mechanical support
Motor regeneration	Disconnect opens without retained absorber	Rail overvoltage/damage/backfeed	9	5	8	360	Motor-side energy absorption/reverse isolation sized from measured energy
Robot mechanics	Torque removal	Collapse/pinch injury	9	6	6	324	Physical restraint and exclusion zone; torque-off alone not safe posture
Jetson branch	Motor sag before shutdown	Abrupt reset/data loss	7	6	6	252	Loaded-voltage budget, early warning, shutdown reserve; evaluate regulated/hold-up alternative if needed
Logic domains	Off-side floating/injection	Spurious clocks/commands or phantom powering	7	5	7	245	Destination isolation plus defined idle bias; test all rail permutations
Head harness	Wrong custom PH4 connection	5V on3V3 GPIO/damage	8	5	7	280	Not Qwiic labels, keyed views and continuity; keep incomplete face disabled
Audio BTL	Output tied to ground/AUX	Amplifier/bench damage	7	4	6	168	Passive rated load, differential probe, two floating speaker leads
Thermal/power connectors	Unbudgeted aggregate current	Overheat/melt	9	5	7	315	Complete load/contact/wire/ground-return budget before power-on
Communications/firmware	Stale/corrupt commands	Loss of control	9	5	7	315	CRC/sequence/bounded queues, timeout, independent hardware watchdog
RF/EMI	Noise/antenna integration error	Sensor/audio faults or noncompliance	6	5	7	210	Radio initially disabled by firmware proposal; certify actual integration and test EMC

U2D2 migration hazards — open,not validated

**USB-on/motor-off DATA backfeed:**omitted VDD conductor does not prevent parasitic DATA injection. No manufacturer powered-off guarantee established. Require numeric leakage/rail-rise limits,measured state matrix and independent emergency-cutoff assessment before commissioning.
**Alternate return through USB/reference:**an open motor return may redirect motor current through communications ground. Qualify external feed/return/fault topology;motor load current must bypass J4/J6/PCB/USB.
**Connector overload:**do not pass all15 motors through one small TTL power contact. Branch gauges,contacts,fuses and thermal/drop margins need actual load/harness data.
**Duplicate USB ownership/stale motor commands:**Jetson DYNAMIXEL SDK service is sole owner;MCU motor master removed. Persistent verified USB identity,unique IDs,watchdog/error handling and tested disconnect recovery are required,but cannot replace independent hardware power disable.
**False safety claim after OE removal:**deleted Q1/Q2 were logic gates,not motor-power switches. Actual protected supply,monitoring,disconnect and regeneration mitigation remain absent.
**USB/module mechanical mismatch:**verify purchased U2D2 revision,cable cavities,mount and strain relief;no mounting geometry or protected cable is approved.

Hazard Categories to Evaluate

Power supply failures (overvoltage, undervoltage, short circuit)
Motor control failures (runaway, stall, overcurrent)
Thermal failures (overtemperature, inadequate dissipation)
Communication failures (loss of control link, corrupted commands)
Environmental failures (moisture ingress, EMI susceptibility)
Mechanical interface failures (connector disconnect, vibration)

Risk Priority Actions

Keep battery and motors disconnected until independent power safety design is captured and checked.
Resolve regeneration and cell-fault behavior; prevent automatic restart/rearm.
Restrain the robot; design safe response to lost torque as well as unexpected torque.
Qualify load budgets, headers, passives, power sequencing and harnesses before any bench authorization.

Open Items

Exact motors now selected:15 XL330-M288-T. No environmental rating,battery specification,measured load profiles,implemented safety circuit or physical tests exist. All scores require reassessment after concrete mitigations/test evidence. Wireless whole-system compliance and antenna integration remain unverified. U2D2 Migration records the current wiring and inherited layout/manufacturing blockers;clean ERC is not safety certification.

Motor power hazard gate — 2026-10-22
Scope
Failure Mode Table
U2D2 migration hazards — open,not validated
Hazard Categories to Evaluate
Risk Priority Actions
Open Items