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Intermediate build

How to build OpenMower

2-DoF robotic lawn mower · Intermediate

OpenMower retrofits YardForce-class robot mowers with an open mainboard, RTK GPS and a Raspberry Pi CM4 for wire-free, centimetre-accurate mowing. About €700 plus the mower.

Start the buildProject files
Difficulty
Intermediate

Some soldering, calibration and Linux comfort needed.

Build time
2–4 weekends

Our estimate, part-time

Parts cost
€700

About €700, excluding the mower and base station, per the README

Degrees of freedom
2

CC-BY-4.0

What is OpenMower?

OpenMower, by Clemens Elflein, replaces the electronics in cheap robot mowers (mostly YardForce Classic 500 and SUMEC-class models) with an open mainboard, RTK GPS and a ROS navigation stack. The result mows accurately without a perimeter wire.

A Raspberry Pi CM4 runs the navigation. If you have no NTRIP correction service, you'll also need your own RTK base station.

The hardware is CC BY 4.0. The README puts the current cost at about €700, not counting the donor mower or a base station.

OpenMower specifications

Donor
YardForce Classic 500(B) and similar
Positioning
Ardusimple RTK2B
Compute
Raspberry Pi CM4
Boundary
None (RTK GPS)

Figures as published by the project. See Sources below.

Bill of materials

PartQtyNotes
Compatible robot mower1
OpenMower hardware kit1
RTK GPS rover and antenna1
Raspberry Pi CM4 with Wi-Fi1
RTK base station—Only if no NTRIP service
Where's the full bill of materials?

The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat €700 as a ballpark from the project. Start at the project repository.

Tools you'll need

  • Screwdrivers
  • Soldering iron
  • A laptop

Step-by-step build overview

Electronics & wiring overview

The OpenMower mainboard connects to the stock motors, and the CM4 and GPS sit on the board.

Battery packpower sourceLaptop / PChigh-level controlEncoderssensingRaspberry Pireal-time controllerMotor driverdrivers / busMotors2 joints / motors
PowerData / commandsSensor feedbackOverview only. Follow the project's own schematic for pinouts and voltages.

Software

The project ships its own firmware and control code. See the repository for setup.

OpenMower ROS stack (GPL or MIT depending on the repo).

Tips from the bench

  • ☕ RTK needs a clear view of the sky, so expect trouble under heavy trees.

OpenMower FAQ

Do I need a perimeter wire?

No. RTK GPS replaces it.

Sources

Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.

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