Hardware documentation for the OpenAMRobot differential-drive mobile base: electrical wiring and pinouts, power distribution, computing, sensors, motor control, the bill of materials, and safety notes.
The physical robot — the base shown above, built and running (here in an SME / logistics setting):
Status: experimental / documentation-first. The electrical, BOM, safety, and now the mechanical CAD (chassis, production files, renders) and datasheets are real and maintained.
Note
This repository is part of the OpenAMRobot vX.X.X release.
Download the complete product release (Hardware + Software + Firmware + UI + Documentation) here:
https://github.com/openAMRobot/openamrobot-release/releases/latest
- Teensy 4.0 GPIO is 3.3 V and NOT 5 V tolerant (abs. max ~3.6 V). Feeding a 5 V signal into a Teensy input can destroy the pin / the board.
- The AS5040 encoders must be powered from the 3.3 V rail, not 5 V. At 5 V their A/B outputs swing to ~4 V and over-drive the Teensy inputs. This was found and fixed on 2026-06-19 — see encoders.md. Do not revert it.
- No fuse and no battery-side disconnect are fitted yet — see Known hardware limitations.
The overall system is shown in the block diagram above.
The configuration the docs describe and that has run the real robot:
| Subsystem | Part | Notes |
|---|---|---|
| Compute | Raspberry Pi 5, 8 GB | Ubuntu Server 24.04 + ROS 2 Jazzy. No active cooler fitted → thermal throttling under the stack. raspberry-pi.md |
| Microcontroller | Teensy 4.0 | micro-ROS motor control. 3.3 V I/O, not 5 V tolerant. teensy.md |
| Motors | ZD Z4BLD60-24GN-30S ×2 | 3-phase BLDC, 24 V, 60 W, 5 pole pairs, 3000 rpm + 1:25 gearbox (4GN 25K) → 120 rpm wheel. motors-drivers.md |
| Motor drivers | ZBLD.C20-120L2R ×2 | 24 V, 7.5 A, 120 W. Set DIP SW4/SW5 = 5 pole pairs. LED fault codes |
| Wheel encoders | AS5040 ×2 | magnetic quadrature, 1024 cnt/rev at wheel scale. 3.3 V supply. encoders.md |
| IMU | MPU6500 (board silkscreen says MPU-6050; actual silicon is a 6500 — WHO_AM_I 0x70) |
3-axis accel + gyro. No magnetometer (/imu/mag carries no real field). 3.3 V. imu.md |
| LiDAR | RPLIDAR A1 — legacy (existing robot) | 2D scan, USB (CP2102). The 2.0 navigation LiDAR is the RPLIDAR S3 (S3M1-R2): USB to the Jetson through a USB to UART adapter, regulated 5 V rail. lidar.md |
| Camera | Raspberry Pi Camera Module 3 NoIR (IMX708) | CSI ribbon, not USB. camera.md |
| Power | 24 V battery (any chemistry; reference build = 2× 12 V in series) | ≥25 V at rest before tests (reference lead-acid threshold). power.md |
Drivetrain (odometry): wheel ⌀ 0.2 m (radius 0.10 m), track 0.46 m — firmware values, physically measured. See the BOM drivetrain section (and the note there about a stale 0.046533 m value that was a CAD artifact).
Internal layout (cover removed):
More views, renders and the full CAD are in mechanical/.
Wiring & pinout (start here for a build): wiring-pinout.md — full Teensy pinout, driver wiring, DIP switches, motor wiring, grounding, ASCII map.
Bill of materials: components-bom.md (electrical) + mechanical-bom.md (sheet metal, fasteners, wheels).
Mechanical CAD: mechanical/ — full STEP assembly, per-part production files (PDF/DXF/SLDPRT/STEP), the SolidWorks project, and renders.
Product architecture: product-architecture.md — the base build vs. the optional/roadmap parts.
- Computing — Raspberry Pi 5 · Teensy 4.0
- Motor control — motors & drivers · driver LED fault codes
- Power — power distribution & battery
- Sensors — encoders (AS5040) · IMU (MPU6500) · LiDAR (RPLIDAR S3; A1 legacy) · camera (IMX708)
- Wiring — wiring & pinout
- 2.0 sensors: sensor index · base camera (Gemini 336L) · IMU (ICM-42688-P) · near-field (MB7060, TF-Luna)
What is included and maintained:
electrical/— computing, motor control, power, sensors, wiring (all populated).mechanical/— CAD (full STEP assembly, per-part production files, SolidWorks project) + renders.manufacturing/bom/— electrical and mechanical bills of materials.manufacturing/assembly/— wheel-assembly guide.datasheets/— component datasheets (re-hosted, manufacturer copyright) + motor sizing calculations.safety/— hardware safety documentation.diagrams/— repository-level diagrams (per-subsystem diagrams live in each subsystem'sdiagrams/).
What is placeholder / not yet populated (empty directories, planned):
electrical/pcb/manufacturing/vendors/interfaces/
Honest disclosure — these are not yet fixed and are safety-relevant:
- No fuse on the 24 V battery. A 24 V battery can deliver hundreds of amps into a short.
Add a 15–20 A fuse/breaker on the battery
+. See power.md. - No battery-side disconnect / hardware E-stop. Only the mains has a switch; there is no fast
cut-off for the 24 V battery. Add a switch/disconnect — ideally an E-stop mushroom — on
+. - No active cooler on the Pi 5 → thermal throttling under the full stack (measured ~83 °C). Fit the official Active Cooler. See raspberry-pi.md.
- Pi 5 bring-up brown-out risk: the 5 V/5 A supply can sag on the current spike at launch, freezing the Pi. See power.md.
- The firmware's 200 ms command watchdog is not a substitute for a physical E-stop.
Hardware and mechatronics documentation belongs here — openamr-platform-hw is the CAD, chassis,
electrical, BOM and manufacturing repo of the OpenAMRobot ecosystem:
Related repositories:
openamr-platform-fw— Teensy motor-control firmware.openamr-platform-sw— ROS 2 software (description, Gazebo, Nav2, docking).
Hardware work involves mechanical, electrical, battery, and motor hazards. Users are responsible for validating mechanical, electrical, battery, and wiring safety, manufacturing quality, and regulatory compliance before building or operating hardware based on this documentation.
CERN-OHL-P-2.0 for original CAD, schematics, mechanical/electrical design files, manufacturing source, and products made from that source. Original documentation is CC BY 4.0, and any software or scripts are MIT. See LICENSE, LICENSING.md, and NOTICE.md.
OpenAMRobot is a project initiated, operated, and controlled by Botshare LTD (Cyprus Company ID HE479056). Botshare LTD owns the transferable economic rights in original OpenAMRobot material created by or validly assigned to it. Third-party material remains subject to its respective ownership, licences, and notices.
Original OpenAMRobot software and firmware are licensed under MIT, documentation under CC BY 4.0, and hardware design source under CERN-OHL-P-2.0, as mapped in LICENSING.md. Public distribution grants the permissions stated in the applicable licence; it does not transfer ownership of underlying copyright, trademarks, patents, or other intellectual property.
Accepted external contributions require DCO sign-off and an applicable Individual or Corporate Contributor Agreement governing assignment of transferable economic rights to Botshare LTD. Contributor attribution and legally non-waivable authorship or moral rights remain recognized.
See the organization IP Policy, Contribution Guide, and Contributor Agreement Process.