It is a conversion kit, not a scratch build, so a compatible commercial robot mower must be bought first, and the reference model is hard to find new.
OpenMower turns a cheap off-the-shelf robotic lawn mower, originally the YardForce Classic 500, into a GPS-guided mower by swapping its stock mainboard for an open-source board running ROS. Instead of bumping around randomly inside a perimeter wire, the converted mower uses RTK GPS to mow recorded areas in planned lanes and is controlled from a phone app. The project reuses the donor mower's chassis, motors, battery and safety sensors.
At a glance
| Parts cost | $790 project · The project's budget of about 700 EUR for the conversion, covering the hardware kit, compute module, GPS receiver and antenna. The donor mower is not included source ↗ |
|---|---|
| Difficulty | 3/5 Intermediate · No fabrication beyond a printed antenna holder, but the build needs intermediate electronics and Linux skills, RTK GPS setup and a compatible donor mower. |
| Build time | Typically a weekend for a YardForce-class mower source ↗ |
| Tools needed | Basic screwdrivers for disassembly, 3D printer for the GPS antenna holder and optional Wi-Fi antenna mount, soldering only if building the mainboard from the KiCad files instead of buying the kit |
| Motors | The donor mower's own drive and blade motors, driven by three xESC motor controllers |
| Controller | Raspberry Pi Compute Module 4 (or CM5) on the xCore board, plugged into the OpenMower mainboard |
| Sensors | RTK GPS receiver (ArduSimple simpleRTK2B or Unicore UM98x), the mower's stock lift, emergency and rain sensors via its cover UI board |
| Published | ✓ Parts list✓ CAD/STL✓ Assembly guide✓ Wiring✓ Software✓ Video Hugo docs website (openmower.de) with step-by-step guide and knowledge base, KiCad PCB repos, Printables mounts, YouTube video, Discord |
| Activity | Last update 2026-09-30 · 6,720 GitHub stars · Discord with 2,000+ members (per README); 409 forks of the main repo |
| Kits | A pre-built OpenMower hardware kit (mainboard, xCore, 3 ESCs) is offered through a community member on Discord rather than a regular store |
Licenses
The design license is non-commercial. Building one for personal, educational or research use is allowed, but selling builds, parts or kits is not.
| Design files | CC BY-NC-SA 4.0 for the main OpenMower repo (original v1 hardware); the newer xtech YardForce mainboard KiCad repo is CC BY 4.0 source ↗ |
|---|---|
| Code | GPL-3.0 (open_mower_ros); mainboard firmware fw-openmower-v2 is GPL-2.0 source ↗ |
| Documentation | Apache-2.0 (openmower.de site source repo) source ↗ |
Builder notes
Practical points from the project's issue tracker, forum and docs, each linked to its source.
- The reference donor mower, the YardForce Classic 500, was reported unavailable new in North America and Europe from 2024, and US builders were still asking in 2026 which base mower to use. The compatibility list should be checked before buying anything. source ↗
- The guides are split by the stock carrier board version (1.2.0 and later versus older), and the YouTube disassembly video is only valid up to about the 5-minute mark, since the rest is outdated. source ↗
- The large universal mainboard is deprecated because boards broke and it did not fit most mowers. It has been split into separate xESC, charger, logic and GPS modules, so older forum advice about it no longer applies. source ↗
- The project's non-commercial license was challenged in an early issue, and the author kept it so others could not manufacture and sell the design before he did. The newer xtech mainboard designs are under the more permissive CC BY 4.0. source ↗
- The ready-made electronics kit is sourced by contacting a community member on Discord. Builders who solder their own boards from the KiCad files need to source the parts from the repos' parts lists. source ↗
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