OpenMower — Open Source RTK GPS Robotic Mower – Knowledge Base

Docs: Compatible Mowers

Mon, 01 Jan 0001 00:00:00 +0000

Yard Force

Check out the Git Repo Here: https://github.com/xtech/hw-openmower-yardforce

The project got started on a YardForce Classic 500(B), and there are photo guides in this documentation on how to disassemble and reassemble it. From a user’s perspective, the YardForce Classic 500(B) is the “best supported” mower.

However, there are more mowers from the YardForce brand that are compatible:

In theory, every YardForce model with the Core + Outer Frame Chassis (SA, SC, LUV, N and NX Line) that has a production year of 2019+ has compatible electronics to replace the stock mainboard with an OpenMower one.

As of today the YardForce Amiro, Compact, EasyMow, MowBest, XPower and MB series models are not (yet) compatible.
The main reason is that the OpenMower mainboard does not fit in their chassis.

SABO / John Deere

There is a dedicated mainboard for SABO MOWit 500F (Series-I & II) and John Deere Tango E5 (Series-I & II) mowers.

Check out the Git Repo Here: https://github.com/xtech/hw-openmower-sabo

This Carrierboard is compatible with the following mower models:

SABO MOWit 500F (Series-I & II)
John Deere Tango E5 (Series-I & II)

Series-I Carrierboard (v0.2)	Series-II Carrierboard (v0.2)

Series-I (v0.1) @ John Deere Tango E5	Series-II (v0.1) @ Sabo MOWiT 500F

These mowers are well supported. Even the display controller was replaced by a fully functional, modern user interface!

Your browser does not support the video tag.

Universal Board

The universal board contains all features needed for an Open Mower build (e.g., three BLDC/DC motor controllers, a LiPo charger on board, connectors for GPS, emergency sensors, etc.). It has screw terminals for easy connections and can be broken into smaller modules if it doesn’t fit as a whole board.

Check out the Git Repo Here: https://github.com/xtech/hw-openmower-universal

Other Compatible Brands

The following mower brands are known to have compatible hardware with the Universal mainboard. If you want to check your specific model, ask on Discord. The probability is high that it will work:

Husqvarna: Most Husqvarna mowers
Gardena: Most Gardena mowers
Fuxtec / Redback: Fuxtec and Redback mowers

Custom Hardware

If you have a custom chassis, there is a good chance you can get it to work with the Universal board. Ask on Discord for guidance on your specific setup.

Docs: Change Hostname

Mon, 01 Jan 0001 00:00:00 +0000

Changing the hostname is simple, thanks to the raspi-config tool:

Run sudo raspi-config
Select System Options -> Hostname
Enter a new hostname and press Enter`
Finish and Reboot

Docs: External Wifi Antenna

Mon, 01 Jan 0001 00:00:00 +0000

After adding the external antenna, you need to tell the Raspberry Pi CM4 to use the external antenna instead of the built-in one.

Terminal Cast

How to edit the antenna configuration

Instructions

You can do this by:

Run sudo nano /boot/firmware/config.txt
Scroll Down to the [cm4] section and:
- Comment # dtparam=ant1
- Uncomment dtparam=ant2
Save CTRL + O and Exit Nano CTRL + X
Reboot the OS by running sudo reboot

Docs: Record Areas

Mon, 01 Jan 0001 00:00:00 +0000

In this section, we finally drive the robot around and test if everything works as expected. Then we will record a map, and you can see the magic happen.

Prerequisites

A smartphone or PC (or a USB gamepad )
Modified robot connected to your network
OpenMower software running on the robot
Docking station powered up
Mower fully charged

Step 4.1: Check the GPS

For this step, put the mower into the docking station and turn it on. It should boot up and get to a solid green status LED.

It is important that the mower is out in the open for the RTK GPS to work. Don’t try this indoors and don’t cover the mower.

Open the OpenMower web app with any device by opening a browser and going to the following URL: http://openmower.local:8080 or http://<your-openmower-IP>:8080.

Wait for the GPS to find a position. This might take some time (up to 30 minutes).

You can see the current GPS quality in the Open Mower app as shown in the graphic above.

You need to have RTK Fixed for the following to work. If you don’t get a good GPS fix, you will need to check your RTK setup and configuration.

Step 4.2: Initialize the Orientation

In addition to the position, the robot also needs to know its orientation. Since we are not using a compass, the robot’s orientation is derived from its movement. In order to initialize the orientation, you need to drive the robot.

You can either use the on-screen joystick in the Open Mower App or a gamepad connected via USB (hold the A button) to drive the robot.

Warning

Don’t pick up the mower or the orientation will be lost again!

Now drive the mower for at least 50m, do some straight lines and some figure eight patterns. Currently, the robot does not know the quality of its orientation estimate, but you can judge by driving and looking at the app.

The orientation is initialized correctly if:

When driving a straight line, the visualization also drives a straight line (no jumps)
When rotating in place, the visualization stays in place and doesn’t jump

Step 4.3: Record a Simple Map

In this step, we will record a simple map. Keep it simple for the first tests and record your map as soon as you’re confident that everything works as expected.

The map for the mower consists of three parts: the docking position, at least one mowing area and optionally navigation areas.

Mowing Areas are the areas which will be mowed. Each mowing area has a single outline and optional areas to exclude (e.g. static obstacles).
Docking Position is the position and orientation of your docking station. It needs to be close to a mowing area or navigation area. This is needed for the robot to find its way to the docking station.
Navigation Areas are areas similar to mowing areas (they consist of an outline and optionally exclusions). The mower is allowed to drive in these areas, but won’t mow. Use these areas to connect mowing areas. Also, if your docking station is not close to a mowing area, you can use a navigation area to allow the robot to drive to the docking station.

Now that the robot knows where it is located, and you know which areas we need to record, start recording your first map. In the following picture, you can see an example.

Record Outline

Drive the robot to the outline. Make sure that the robot is facing in counterclockwise direction.
Start the recording by pressing Start Recording.
Drive around the mowing area. Make sure that the GPS position stays fixed at all times.
Stop the recording using Stop Recording.
The outline should now turn green. This means it’s done recording, and you can move on to recording exclusions.

Optional: Record Exclusions

If your area has zones you want to exclude (e.g. static obstacles), you can record them like this:

Drive the robot to the edge of the exclusion zone. Make sure that the robot is facing in clockwise direction.
Start the recording by pressing Start Recording.
Drive around the area to exclude. Make sure that the GPS position stays fixed at all times.
Stop the recording using Stop Recording.
The outline should now turn red. This means it’s done recording, and you can move on to recording more exclusions.

Save Area

If you are happy with your recording, you can save the area. In order to do this, click the Finish Area button. A dialog will appear asking if you want to save the area as mowing or navigation area. Alternatively, you can also discard the recording.

As soon as the area is saved, the area will turn solid. Mowing areas will be displayed in green, navigation areas will be shown in white.

Record Docking Position

In order to record the docking position, do the following:

Drive to a location about 2 m in front of your docking station.
Make sure you have a GPS fix and press the Record Docking button.
Now drive close to the docking station. The front wheels of the robot should be at the edge of the docking station. Don’t fully drive into the docking station!.
Make sure you have a GPS fix and press the Record Docking button.
The app should move the home icon to your current location. Now you can fully drive into the docking station.

Finish Recording

Finish the process by pressing Exit Recording. Now the mower should go to IDLE mode. You should be able to start mowing by pressing the Start button. The mower will undock, wait for GPS and mow the area.

Docs: Managing ROS Parameters

Mon, 01 Jan 0001 00:00:00 +0000

Viewing and Configuring ROS Parameters

OpenMower is built on ROS, which means much of its behavior is controlled through parameters. Understanding how to inspect and modify these parameters gives you fine-grained control over your mower’s operation.

Listing All Parameters

To see all currently active ROS parameters, open the OpenMower shell:

openmower shell

Then run:

rosparam list

This will display a full list of parameters currently loaded in the system. It’s a useful first step when debugging or trying to understand how your mower is configured.

Overwriting Parameters

All parameters can be customized using the mower_params.yaml configuration file. This file acts as the central place to override default values.

The easiest way to edit it is with:

openmower configure ros

Example

In this example we will be overwriting the speed parameter.

1. Fetch the Parameter’s current value

After discovering a parameter you want to edit using rosparam list, you can get the value using rosparam get <parameter>:

🚜 openmower@openmower-v2:~$ rosparam get /move_base_flex/FTCPlanner/speed_fast
0.4

In this case, our speed is currently at 0.4 m/sec for mowing

2. Change the value for your config

On the host system call openmower configure ros and translate the parameter name to YAML. This is done by replacing each / into indentations (2x space).

For our example it looks like this:

move_base_flex:
 FTCPlanner:
 speed_fast: 0.5

3. Save the file and check the updated value

After saving the file, ROS is automatically restarted and you can check, if the value is now updated:

🚜 openmower@openmower-v2:~$ rosparam get /move_base_flex/FTCPlanner/speed_fast
0.5

🎉 Done!

If you have issues

If some parameter isn’t overriding correctly, make sure you are on the latest version of OpenMower. If it still doesn’t work ask on Discord.

Docs: Configuring GPIO Inputs

Mon, 01 Jan 0001 00:00:00 +0000

Overview

OpenMower supports configuring GPIO pins as digital inputs that can trigger emergency stops or other events. Common use cases include:

Wheel lift sensors — detect when the mower is lifted
Stop buttons — physical emergency stop buttons on top of the mower

Step 1: Create the inputs configuration file

Create /home/openmower/params/inputs.yaml with your GPIO input definitions:

gpio:
 - name: Front left wheel lift
 line: GPIO10
 active: low
 emergency:
 reason: lift
 delay: 2500

 - name: Front right wheel lift
 line: GPIO11
 active: low
 emergency:
 reason: lift
 delay: 2500

 - name: Top stop button 1
 line: GPIO12
 active: low
 emergency:
 reason: stop
 delay: 10

 - name: Top stop button 2
 line: GPIO13
 active: low
 emergency:
 reason: stop
 delay: 10

Configuration fields

Field	Description
`name`	Human-readable label for the input
`line`	GPIO pin name (e.g. `GPIO10`)
`active`	Logic level that triggers the event — `low` or `high`
`emergency.reason`	Emergency type — `lift` for wheel lift, `stop` for stop button
`emergency.delay`	Debounce/delay in milliseconds before the emergency is triggered

GPIO Pin Mapping

The example config above uses GPIO10–GPIO13. Here is how those map to physical connectors on each board.

OpenMower Universal Board

Orientation: looking at the board with the ethernet ports facing you.

Position	GPIO
Top left	GPIO13
Top right	GPIO12
Bottom right	GPIO11
Bottom left	GPIO10

OpenMower Yardforce Board

Orientation: looking at the board with the ethernet ports at the bottom left, pins sorted top to bottom.

Position	GPIO
1st (topmost)	GPIO10
2nd	GPIO11
3rd	GPIO12
4th	GPIO13

Step 2: Enable the input service

Add the following to your mower_params.yaml (or custom_params.yaml for Universal board builds):

ll:
 services:
 input:
 config_file: /data/params/inputs.yaml

To open the file for editing:

openmower configure ros

Path mapping on OSv2

On OSv2, /home/openmower/params is mapped to /data/params inside the container. If you are on a different setup, adjust the config_file path accordingly.

Step 3: Restart OpenMower

After saving both files, restart the service to apply the changes:

openmower restart

Your GPIO inputs are now active and will trigger the configured emergency events when the specified logic level is detected.

Docs: Flashing the CM4 eMMC

Mon, 01 Jan 0001 00:00:00 +0000

CM4 with eMMC only

This guide applies only to CM4 variants with onboard eMMC storage. The CM4 Lite variant has no eMMC — it uses a microSD card instead and does not require this process.

Check your CM4 model number: variants with eMMC have the storage size in the name (e.g. CM4008032 = 32 GB eMMC). Lite variants are explicitly labelled “Lite” (e.g. CM4008000).

The CM4 with eMMC has onboard flash storage instead of a microSD slot. To flash a new image, you need to put it into USB boot mode so it appears as a mass storage device on your computer.

This guide covers the OpenMower-specific steps. For full reference, see the official Raspberry Pi documentation .

Prerequisites

A host computer (Linux, Windows, or macOS)
A micro USB cable (connected to the USB port on the xCore board)
The OS image you want to flash (e.g. OpenMower OS)

Step 1: Enter USB boot mode

The xCore board has an Rpi Boot button (left of the two buttons, label printed below the CM4 slot).

Hold the Rpi Boot button.
While holding it, connect power to the xCore board (or plug in the micro USB cable to your host computer).
Release the button once powered.

The CM4 is now in USB boot mode.

Step 2: Install rpiboot on your host computer

sudo apt install rpiboot
sudo rpiboot

Download and run the installer from the usbboot releases page .
Reboot your computer after installation.
With the CM4 in USB boot mode, open Start → rpiboot - Mass Storage Gadget.

Build rpiboot from source, then run:

rpiboot -d mass-storage-gadget64

See the usbboot repository for build instructions.

Within a few seconds the CM4’s eMMC will appear as a USB mass storage device on your computer.

Tip

If the device is not recognised, avoid USB hubs — connect the micro USB cable directly to your computer.

Step 3: Flash the image

Use Raspberry Pi Imager to write your OS image to the eMMC device. Select the eMMC as the target storage — it will appear like any other USB drive.

Alternatively, use dd on Linux/macOS:

sudo dd if=your-image.img of=/dev/sdX bs=4MiB status=progress oflag=sync

Replace /dev/sdX with the actual device path of the eMMC. Double-check this before running.

Step 4: Boot from eMMC

Once flashing is complete, disconnect the micro USB cable and power-cycle the board. The CM4 will boot from the newly flashed image.

Docs: Creating a Debug Recording

Mon, 01 Jan 0001 00:00:00 +0000

When investigating issues — especially positioning problems — a rosbag recording gives developers a full snapshot of sensor data to analyse. This guide walks you through recording one and retrieving it from your mower.

Privacy notice

A rosbag records raw sensor data, which includes the GPS position of your mower. By sharing the file you disclose the physical location of your garden. Only share it with people you trust.

Prerequisites

OpenMower is running and the mower has a GPS fix (green GPS icon in the app)
You can access the mower via SSH or the web terminal

Step 1: Start the recording

Connect to your mower via SSH or the web terminal, then enter the ROS shell:

openmower shell

Once inside, navigate to the recordings directory and start recording all topics:

cd /data/recordings
rosbag record -a

This records all active ROS topics. Leave the terminal open — the recording runs until you stop it with Ctrl+C.

Step 2: Enter area recording mode

Open the OpenMower app and activate area recording mode — the same mode you use when recording mowing areas. This ensures all relevant topics (GPS, IMU, wheel odometry) are actively publishing at full rate.

GPS fix required

Make sure the GPS icon in the app is green before driving. Recording without a fix produces data that cannot be used for analysis.

Step 3: Drive the test patterns

Drive the mower through the following patterns. Each one exercises a different aspect of positioning:

Pattern	Purpose
Straight lines	Linear odometry and GPS consistency
Figure-8	Combined turning and straight-line tracking
Rotate on the spot (clockwise)	Yaw estimation, IMU vs. GPS heading
Rotate on the spot (counter-clockwise)	Same, opposite direction

A minute or two of each pattern is sufficient. You don’t need a large area — a small open patch of lawn works fine.

Step 4: Stop the recording

Once done, go back to the terminal and press Ctrl+C, then type exit to leave the ROS shell.

The .bag file is now in ~/recordings/ on the mower. List the directory to find your filename:

ls -lh ~/recordings/

The filename includes a timestamp, e.g. 2024-06-01-12-34-56.bag.

Step 5: Retrieve the file

Copy the .bag file from ~/recordings/ on the mower to your computer.

Linux / macOS
Windows

Use scp from your local terminal:

scp openmower@<mower-ip>:recordings/<filename>.bag .

Replace <mower-ip> with your mower’s IP address and <filename> with the actual filename. The file downloads to your current directory.

Windows 10 (build 1809 or later) and Windows 11 include an OpenSSH client. Open Command Prompt or PowerShell and run:

scp openmower@<mower-ip>:recordings/<filename>.bag .

On older Windows versions, use a graphical SFTP client instead:

WinSCP — free, open source
Cyberduck — free, cross-platform

Connect with protocol SFTP, host <mower-ip>, user openmower, and navigate to /home/openmower/recordings/ to download the file.

Tip

.bag files compress very well. Zipping before sharing can reduce the file size significantly:

Once you have the file, share it with whoever is helping you debug — via Discord, a file sharing service, or any other method that works in context.

Step 6: Clean up

Once debugging is done, delete the recordings from the mower to free up disk space:

# delete a specific file
rm ~/recordings/<filename>.bag

# delete all recordings
rm ~/recordings/*.bag

Docs: Hardware Versions / Known Issues

Mon, 01 Jan 0001 00:00:00 +0000

Current Hardware (v2 Hardware Platform)

For v2 Hardware Platform, please check the corresponding repository for changes and known issues:

YardForce: https://github.com/xtech/hw-openmower-yardforce
SABO / John Deere: https://github.com/xtech/hw-openmower-sabo
Universal: https://github.com/xtech/hw-openmower-universal

0.13.0 - Red

Notable changes

Custom CoverUI added to the kit
Dropped support for dfPlayer sound module

Known issues

2.5mm screws were missing (used to fasten RPi4). Affect kits shipped before June'23.
The first batch of 0.13 boards was mistakenly labeled “latest”. No action needed.
Outdated Firmware . Affect kits shipped before May'23.
IC2 chip is wrong . Affect kits shipped before May'23.
rain sensor cable is female, but needs to be male . Affect kits shipped before May'23.

Legacy Hardware (v1 Hardware Platform)

Information

V1 hardware used a completely different architecture to v2 hardware which makes it hard to port to new mower models. If you currently own a v1 hardware kit, this is nothing to worry, the kit will continue to work with your mower, there is no real benefit of upgrading it to a v2 hardware kit. For new builds, the v2 hardware platform is recommended.

0.13.0 - Red

Notable changes

Custom CoverUI added to the kit
Dropped support for dfPlayer sound module

Known issues

2.5mm screws were missing (used to fasten RPi4). Affect kits shipped before June'23.
The first batch of 0.13 boards was mistakenly labeled “latest”. No action needed.
Outdated Firmware . Affect kits shipped before May'23.
IC2 chip is wrong . Affect kits shipped before May'23.
rain sensor cable is female, but needs to be male . Affect kits shipped before May'23.

0.12.0 - Black

Notable changes

IMU: LSM6DSO instead of WT901

Known issues

SPI tracks from Pico were misplaced, already fixed in firmware. No action needed.
Outdated Firmware
IC2 chip is wrong
rain sensor cable is female, but needs to be male

0.11.0 - Purple

Notable changes

Connected WT901 via I2C freeing pins for dfPlayer
Upgraded dock station PCB with extra holes and terminals (red)

Known issues

IC2 chip is wrong

0.10.0 - Green

Notable changes

Added dock station PCB (green)

Known issues

IC2 chip is wrong

0.9.3 - Also Green

First build. Experimental xESC2040 instead of xESC-mini (STM32).

Docs: Configuring xESC

Mon, 01 Jan 0001 00:00:00 +0000

The xESC motor controllers can be configured to work with many BLDC and DC motors. The firmware for the controllers is based on the open source VESC project and therefore, the controllers can be configured using the VESC Configuration Tool.

Prerequisites

Windows or Linux computer to run the VESC Configuration Tool
VESC Tool (https://vesc-project.com/vesc_tool ) You can download the tool for free by adding the “free” version in your cart and proceeding to checkout.
OpenMower Firmware needs to be successfully installed in the xCore board. This is needed because the xCore bridges the connection between your computer and the xESC. If you haven’t done it, follow the Firmware Update guide.
Optional (but makes your life easier):
Configuration files for the mower you are using.
Look in the OpenMower repository for the files suited for your mower.
You will need three files:
- App configuration XML (sets the baud rate, etc. Same for all three xESC controllers)
- Mower Motor configuration XML (motor parameters for the mower motor)
- Drive Motor configuration XML (motor parameters for the wheel motors)

Configuration Process

Stop ROS from interfering with the controllers

openmower stop to stop ROS from interfering with the controllers during configuration.

Expose the ESC to the network

Run openmower expose-xesc [left|right|mower] to expose the xESC controller (choose left, mower or right).
The controller is then reachable in your local network on openmower:65102 until you hit Ctrl + C.

Connect to the xESC

Open the VESC Configuration Tool and connect to the xESC controllers by clicking:

Connection -> TCP [1]
Insert the IP address of your mower or openmower into the Address field [2].
Set the port to 65102 [3]
Click Connect [4]

Information

If you encounter this warning message:

you can safely ignore it. The VESC tool is backward compatible with the firmware version used on the xESC controller.

Configure xESC

Upload the configurations

With the VESC Configuration Tool connected, you can now upload the configuration to your xESC controllers:

[Image 1]: Click File -> Load Motor Configuration XML
[Image 2]: Select the motor configuration XML file for your motor (different for mowing motor and the drive motors)
[Image 3]: Ignore the version message, if it appears
[Image 4]: Click Write Motor configuration. The green banner will appear on success.
[Image 5]: Click File -> Load App Configuration XML. Ignore the version message, if it appears
[Image 6]: Click Write App configuration. The green banner will appear on success.
Hit Ctrl + C in the openmower terminal to stop exposing the xESC controller.

Repeat these steps for all three of the three xESC controllers.

Required preparations

Remove the mower blade.
Really, remove the blade! This is a huge mower with a strong motor and large blade! 💀
Lift the mower’s rear so wheels can spin freely (use a carton, block or stand).
Unmount the mower blade!
Use battery power for calibration (not dock power), and ensure the battery has sufficient charge.
Check if you disassembled the mower blade!

Drive motor calibration (left then right)

Perform calibration for left drive first, then repeat the procedure for the right drive.

Enable realtime data: Later on, we wanna validate our calibration with a known reference value, but also during calibration it’s interesting to see the displayed values in the marked 2 window. That’s why we enable real-time data first:
Start the FOC Calibration Wizard:
Now we need to provide some specs of our motor. These are the specs for the left and right drive motors, for the mow motor, we need to use other specs:
🡆 🡆

🡆 🡆
Once calibration has been done, do not change the direction (even though the left wheel turns forward during calibration, whereas the right one backwards):
Now that the calibration succeed, lets test the result:

Test with “D 0,4” (1) and press the “Duty cycle” play button (2). If it draw <= 0.15A (3) and sound healty, it is calibrated well.
Test with some higher duty settings. It will become more loud for sure, but should always spin smooth and sound healty. If not, press the STOP sign (4).
As a last important step, load the correct ESC-App config via: File → Load App Configuration XML, choose SABO_Drive-App.xml (see SABO ESCs configs ) and finally press the ↧A icon (Write app configuration) on the right side.

Done 😆
… but not finished ✌️ … you need to do the whole procedure again, but with the right drive side.

So, Ctrl+c your openmower expose-xesc left, and do it again but with openmower expose-xesc right.

Mow Motor Calibration

For the mow motor ESC calibration, you do the same workflow, but with adapted values:

openmower expose-xesc mower
During FOC Calibration Wizard use the following values:
- Tab “Motor” = Medium Inrunner ~750g
  - Advanced: Max Power Loss = 200, Motor Poles = 8
- Tab “Battery”
  - Battery Capacity = 3.9Ah (same as before)
- Tab “Setup”
  - Gear Ratio = Check Direct Drive
  - Motor Poles = 8
  - Motor Temp. Sensor = disabled
Test with “D 0,08” which should draw <= 0.52A (without assembled blade)
Check/Adjust blade rotation direction:
We need to ensure that the blade rotate CCW (when watching from downside onto the axis). Do this with a slow rotation speed like “D 0,08”.

If it rotates CW, change direction via: Motor Settings → General → Tab General → Invert Motor Direction. Do not forget to do: “Write motor configuration” via ↧M
Load the correct ESC-App config via: File → Load App Configuration XML, choose SABO_Mower-App.xml (see SABO ESCs configs ) and finally press the ↧A icon (Write app configuration) on the right side.
Limit blade RPM:
It’s important to limit the max. RPM to the one like OEM is running it! Otherwise you risk your motor bearings or more dangerous: Your blade might fly away 💀

Choose your adventure. Your build, your rules.

Docs: Firmware Update

Mon, 01 Jan 0001 00:00:00 +0000

Warning

Early versions of the xCore board have a bug in the bootloader which sometimes prevents the board from being detected by the openmower tool.

If you encounter Timeout errors during the firmware installation process, update the bootloader by running: openmower update-bootloader and try again.

To install the firmware to the xCore board, simply run: openmower update-firmware. The openmower tool will read your environment variables, download the appropriate firmware binary and upload it to the xCore board via Ethernet.

The expected output is shown below:

Example output for openmower update-firmware command.

Docs: GPS / Coordinate System

Mon, 01 Jan 0001 00:00:00 +0000

Positioning / Coordinate System

Positioning in the Open Mower project is done in a local 2D coordinate system. This means that the robot’s current position can be described by the coordinates (X / Y) of the VRP and the current orientation.

The origin of the coordinate system can either be chosen freely by the user or can be set to the base station. If an external correction service is used, the origin has to be specified manually.

Open Mower uses a right-handed ENU coordinate system.

Docs: GPS Base Setup

Mon, 01 Jan 0001 00:00:00 +0000

This part of the documentation is work in progress. There are many ways of setting up the RTK base, here is one using RPi 0W, ZED-F9P and a web based software RTKBase. On discord you may ask karl.ranseier for support.

Prerequisites

Raspberry Pi 0W
µSD card
Power supply for RPi
Ardusimple ZED-F9P
A cable or combinatin of cables to connect micro usb male to micro usb male:
- A) Direct like this
- B) Adapter (like this ) + micro usb to usb-a cable
A windows PC
Stable internet connection (no disconnection within one hour)

Installation

If you know about RPi and have already a functional OS, you may head on to “Software”, but in my case it did not work using an older image.

Preparing sd card

Download RPi Imager for windows
Start Imager:
Choose your RPI (in my case RPi 0W, choosing wrong RPi will most probably result in many problems)
Choose Operating system “Raspberry Pi OS lite (legacy, 32bit)
Select your sd card:
Press next so this will appear:
Edit settings like the following (and use your personal WiFi settings and country), where you set a good password for your Pi account. Username and password are case sensitive!
activate SSH:
Press save to see this:
Click on YES and allow to overwrite the data on your sd card (if you are sure, that you will not miss them). It will start downloading and writing the data:
Wait until it is finished, it may take half an hour, depending on your internet connection ;-)

Start your RTKBase RPi

Put your sd card into your RPi
Connect ZED-F9P via usb to your RPi (NOT after the installation, it will be configured during installation).
Power your RPi

Connect to RPi

Get from your router the IP of your RPi
Start PuTTY and connect to RPi, where you enter the local IP of your RPi
Enter your Username Pi, press enter and than enter your password:

Software

Is your ZED-F9P connected? Do it!
We will use RTKBase
To install it, you can use the following lines, which you can copy and paste at once. The original recommendation is no sudo in front of chmod. That did not work for me.
```
cd ~
wget https://raw.githubusercontent.com/Stefal/rtkbase/master/tools/install.sh -O install.sh
sudo chmod +x install.sh
sudo ./install.sh --all release
```

A very long output should follow. It ends with:

GNSS Configuration: done
################################
STARTING SERVICES
################################
Created symlink /etc/systemd/system/multi-user.target.wants/str2str_tcp.service → /etc/systemd/system/str2str_tcp.service.
Job for gpsd.service failed because the control process exited with error code.
See "systemctl status gpsd.service" and "journalctl -xe" for details.
################################
END OF INSTALLATION
You can open your browser to http://192.168.178.34 (here the editor deleted IPV6)
################################
Pi@RTKBase:~ $

Installation finished, go on and configure your RTKBase

Configuring your RTKBase

Start a browser and enter the IP address of your RTKBase. You will get this:
Enter as password admin. On the following site press the copy symbol right to PPP.
Go to settings and press “options” right to “Main Service”, than paste your coordinates to “Base coordinates”:
Press on options again, than on options right to “Caster Service”
Here you have to enter the setting set up in your mower, standard is: username gps and password gps. Select the right mount point. I have named it like my city, in mower config and here.
Save the config
Switch on “Caster Service” and “File Service”, it should look like this:
Eventually change your password below these options.
At logs you should find at least two files:

Find the position of your RTKBase

There are several ways to find your position. To use openmower you do not need the perfect position. Therefore the first option should be your choice, if you want a fast and good result for openmower.

Easy and good way

Click on the symbol right to PPP to copy the values to the clipboard:
Enter these values to your options at MainService.
Save
ReActivate Ntrip Service
Finished!

More complicated and more exact way

You have to set up the logging of your position as mentioned above by activating “file service”. You should wait for a day to average all the values to get a high precision position.
After midnight you find a zip-file at logs. This you can convert to a Rinex file. To understand this file you may check RINEX-File , but you don’t need it.
Press on the pencil right to the zip-file:
“Create Rinex file”:
Download it when finished (may take a while, some minutes or longer)
Go to Calculator , upload your Rinex file and enter your email address. Don’t forget to enter the “no robot”-verification.
When you received the email, look at “ITRF2014” (or search for “longitude”) and see your values like LONGITUDE 6.XXXXXXXXX° LATITUDE 51.XXXXXXXXX° HELL 79.9041
You enter these values to your options at MainService. Be aware that the order of LONGITUDE and LATITUDE is switched!
Save
ReActivate Ntrip Service
Finished!

Thanks to Stefal and all the contributors of RTKBase and the used resources.

Docs: Shopping List

Mon, 01 Jan 0001 00:00:00 +0000

If you make a purchase through the links marked with an Asterisk (*), I may earn a small commission at no extra cost to you. Thank you for supporting this project!

Warning

Read this first: Important Info

Parts for the Robot and the Charging Station

Name	Description	Quantity Required	Source Link	Notes
Mower (YardForce Classic 500(B))	The mower to modify.	1	Amazon*	Check the Compatible Mowers
Open Mower Hardware Kit	The electronics we will mount inside the robot and the charging station. Also includes goodies to make stuff easier to mount.	1	Version 2 Hardware: (see Announcement ) Contact @Apehaenger on Discord, he has Hardware available Version 1 Hardware: Vermut’s shop	Alternatively you can source and solder most of these parts yourself. Check the repositories in the Links section for PCB designs and BOMs.
Ardusimple RTK2B GPS + Antenna	Positioning system for the robot	1	ArduSimple	Some users use UM9XX chips (available from WitMotion and AliExpress ) as alternative. Compared to ArduSimple, they’re a bit cheaper and support triple-band frequencies.
Raspberry Pi Compute Module 4 with WiFi	The brain of the robot. RAM: 2GB+ for running the software 4GB+ for development 16GB+ storage (eMMC or µSD Card)	1	RPi Locator	Yes, it has to be the Raspberry Pi CM4, because we need all the UARTs and it goes into the xCore board.
µSD Card	Only for RPi CM4 Lite. The absolute minimum capacity you should buy is 16GB. But better buy a 32GB one	1	Amazon* or your local hardware store	A Gucci option would be a RasPiKey
Optional:	Optional:
USB Wi-Fi Dongle	For better Wi-Fi reception	0		Check for Linux Support
Left-Angle USB adapter	If you want to keep Wi-Fi dongle inside the mower. RPi USB is really close to the mower side wall	0	Amazon* or your local hardware store	The kit contains the wire to connect external USB port. That may be enough if Wi-Fi dongle is waterproof.

Parts for the GPS Base Station

Info

You only need a GPS base station if you don’t have access to an external NTRIP service. There are multiple free services available, so check before buying this.

Name	Description	Quantity Required	Source Link	Notes
Raspberry Pi + SD Card + Power Supply	You can basically use any Raspberry Pi for this. No special requirements.	1	e.g. Raspberry Pi 4
Ardusimple RTK2B GPS + Antenna	Positioning system for the base station	1	ArduSimple	See above

For the setup check the GPS Base Setup Guide

Docs: The Map

Mon, 01 Jan 0001 00:00:00 +0000

The Map

The most important information for the Open Mower is its map. The map tells the robot in which areas the robot is allowed to drive (= Navigation Area), which areas need to be mowed (= Mowing Area) and where the docking station is located. Using this information, the robot is able to do its work automatically.

Each area consists of one outline and multiple obstacles. The mower is allowed to drive inside the outline of all areas, except for the obstacles. This way you can exclude some parts of your lawn and prevent the mower from entering them.

The map is stored in the map.json file that is located on the mower at /home/openmower/ros_home

Docs: Unicore GPS Modules

Mon, 01 Jan 0001 00:00:00 +0000

Several users have chosen alternative GPS RTK modules with chips by Unicore:

UM960
UM980
UM982

These chips are sold in different variants. Some come with a USB-C socket (so they can be connected directly to the Raspberry Pi). Some have a different antenna socket, which requires an SMA F to MMCX M90 cable.

Compared to the ArduSimple simpleRTK2B, they are a bit cheaper and support triple-band frequencies.

Connection options

Connection	Notes
Module USB-C → RPi USB	e.g. with angle connector
Module UART → MainBoard UART	requires header connectivity

Configuration options

Method	When to use
Vendor software (UPrecise) on Windows	Before installing module into mower
Over UART bus (terminal only)	When RPi is installed and operational

Software

The vendor offers UPrecise to check all status details and configure the receiver. The UI is pleasing and has many features, but also quite some bugs. The download requires creating a free account.

Configuration via UPrecise (USB)

Receiver

Connect to the receiver via UPrecise. COM3 is used when connected via USB. Paste the following commands into UPrecise:

FRESET
CONFIG COM3 460800
MODE ROVER UAV
GPGGA 0.1
GPGSV 1
GPRMC 1
GPGSA 1
GPVTG 1
GPGST 1
SAVECONFIG

You can also connect directly to the receiver’s TTY, but make sure to send CR+LF (\r\n) line endings — otherwise commands won’t be recognized.

OpenMower (`mower_config.txt`)

export OM_GPS_PROTOCOL="NMEA"
export OM_GPS_PORT="/dev/ttyUSB0"
export OM_GPS_BAUDRATE="460800"

Configuration via UART (mainboard)

Use this method when the RPi is already installed and you want to wire the module directly to the mainboard UART header.

Prerequisites

Modified mower with replaced mainboard
RPi with openmower service running

Step 1 — Solder headers on the UM9XX

You only need the 4 middle pins from the 6 available: GND, VCC, TX, RX.

The remaining 2 pins are not needed:

EN — can be used to temporarily shut down the module
PPS — pulse-per-second signal, useful only if you need precise timing

Step 2 — Wire UM9XX to the mainboard

An adapter board is available as an alternative to manual wiring.

MainBoard	UM9XX
TXD	TXD
RXD	RXD
5V_IN	VCC
GND	GND

Step 3 — Configure UM9XX over UART

Install miniterm (part of python3-serial):

sudo apt-get install python3-serial

Stop the openmower service so it does not occupy the UART bus:

sudo systemctl stop openmower

Connect to the UART bus at the default baud rate (115200):

python -m serial.tools.miniterm /dev/ttyAMA1 115200 -e

Press Enter after each command to send it to the receiver.

Note: The following commands assume you wired to the bottom lane (COM1). If you used a different lane, replace COM1 with COM2.

Factory-reset the module and note the response:

FRESET

Expected output:

$command,FRESET,response: OK*4D
system is rebooting
..........
$devicename,COM1*67

Set the baud rate to 460800:

CONFIG COM1 460800

Exit miniterm with Ctrl+], then reconnect at the new baud rate:

python -m serial.tools.miniterm /dev/ttyAMA1 460800 -e

Note: If commands get no response, the baud rate or COM port is wrong. Reconnect at 115200, run FRESET, and try again.

Configure NMEA output. Each GP* command produces extra output — make sure SAVECONFIG completes successfully at the end:

MODE ROVER UAV
GPGSV COM1 2
GPRMC COM1 1
GPGSA COM1 1
GPVTG COM1 1
GPGGA COM1 0.5
SAVECONFIG

Expected output after SAVECONFIG:

$GNGGA,192705.50,,,,,0,00,9999.0,,,,,,*45
$command,SAVECONFIG,response: OK*55
$GNGGA,192706.00,,,,,0,00,9999.0,,,,,,*43
$GPGSA,,1,,,,,,,,,,,,,,,,*73
$GNRMC,192706.00,V,,,,,,,030625,0.0,E,N,V*7B

Exit miniterm with Ctrl+].

Step 4 — Configure OpenMower

Run openmower configure ros and set the GPS protocol to NMEA and the baud rate to 460800.

With your RTK base configured, take the mower outside and verify you get a GPS fix.

Troubleshooting — receiver resets

If the receiver cannot get a fix, a reboot may help. UPrecise provides three reset buttons. Unlike FRESET, these do not wipe the configuration:

Button	Command	Effect
Hot Start	`RESET`	Quick restart
Warm Start	`RESET EPHEM`	Clears ephemeris data
Cold Start	`RESET EPHEM ALMANAC IONUTC POSITION`	Full data reset

See section 8.3 (“Reset”) in the Unicore command reference for details.

Docs: Using a Gamepad

Mon, 01 Jan 0001 00:00:00 +0000

Using a USB gamepad is the most intuitive way to control your OpenMower during the area recording process. Instead of relying on the on-screen joystick in the web app, a physical controller gives you precise control over the mower’s movement — making it much easier to drive clean outlines around your mowing areas.

Any Xbox-compatible USB gamepad works out of the box. Simply plug it into one of the USB ports on your Raspberry Pi and OpenMower will detect it automatically. No additional configuration is needed.

Recording Mode Required

Gamepad control only works while OpenMower is in recording mode. Enter recording mode using the OpenMower app before using any of the buttons below.

If no map has been recorded yet, OpenMower will automatically start in recording mode — no action needed.

Video Tutorial

The video below walks through the entire area recording process, including how to use the gamepad to drive the mower and save mowing areas.

Button Reference

OpenMower Gamepad Controls (image licensed from shutterstock.com)

The table below covers every button used during normal operation and area recording. Most of your time will be spent holding A to drive and using B to start and stop recordings.

Driving

Input	Action
Hold A + left analog stick	Drive the mower
RB	Turbo mode (faster driving)

Recording Areas

Input	Action
B	Start / stop recording the current polygon
Y + D-PAD UP	Finish and save current area as a navigation area — the mower can drive here but will not mow
Y + D-PAD DOWN	Finish and save current area as a mowing area — at least one is required

Docking Station

Recording the docking station requires two separate position fixes that define the approach direction. The line between these two points tells the mower which way to face when returning to dock.

Drive the mower to a point roughly 1.5 m in front of the docking station, facing toward it. Press X to record the first point.
Drive the mower forward until the front wheels are just at the edge of the docking station — do not fully drive in. Press X again to record the second point.

Input	Action
X (first press)	Record approach point ~1.5 m in front of the dock
X (second press)	Record dock entry point at the edge of the station

OpenMower — Open Source RTK GPS Robotic Mower – Knowledge Base

Docs: Compatible Mowers

Yard Force

SABO / John Deere

Universal Board

Other Compatible Brands

Custom Hardware

Docs: Change Hostname

Docs: External Wifi Antenna

Terminal Cast

Instructions

Docs: Record Areas

Prerequisites

Step 4.1: Check the GPS

Step 4.2: Initialize the Orientation

Warning

Step 4.3: Record a Simple Map

Record Outline

Optional: Record Exclusions

Save Area

Record Docking Position

Finish Recording

Docs: Managing ROS Parameters

Viewing and Configuring ROS Parameters

Listing All Parameters

Overwriting Parameters

Example

1. Fetch the Parameter’s current value

2. Change the value for your config

3. Save the file and check the updated value

If you have issues

Docs: Configuring GPIO Inputs

Overview

Step 1: Create the inputs configuration file

Configuration fields

GPIO Pin Mapping

OpenMower Universal Board

OpenMower Yardforce Board

Step 2: Enable the input service

Path mapping on OSv2

Step 3: Restart OpenMower

Docs: Flashing the CM4 eMMC

CM4 with eMMC only

Prerequisites

Step 1: Enter USB boot mode

Step 2: Install rpiboot on your host computer

Tip

Step 3: Flash the image

Step 4: Boot from eMMC

Docs: Creating a Debug Recording

Privacy notice

Prerequisites

Step 1: Start the recording

Step 2: Enter area recording mode

GPS fix required

Step 3: Drive the test patterns

Step 4: Stop the recording

Step 5: Retrieve the file

Tip

Step 6: Clean up

Docs: Hardware Versions / Known Issues

Table of Contents

Current Hardware (v2 Hardware Platform)

0.13.0 - Red

Notable changes

Known issues

Legacy Hardware (v1 Hardware Platform)

Information

0.13.0 - Red

Notable changes

Known issues

0.12.0 - Black

Notable changes

Known issues

0.11.0 - Purple

Notable changes

Known issues

0.10.0 - Green

Notable changes

Known issues

OpenMower (`mower_config.txt`)