Free wheel sensor

Idea

Add a rotation sensor to the free wheel to detect 'motion/no motion over ground' of the mower and thereby detecting obstacles. The sensor simulates a bumper (if no motion detected it triggers like a bumper).

The sensor is based on a compass module (which internally measures magnetic field changes via hall sensors) and rotating magnets.

Photos

Videos

Principle test https://www.youtube.com/watch?v=SGfPwGnzHT4

Outdoor test https://www.youtube.com/watch?v=UbwwP1jQigM

Required components

• Arduino Nano (placed into printed 3D part) and powered (VIN pin) via Ardumower PCB 9V output pin
• HMC5883 compass sensor (placed into printed 3D part)
• 4 ball magnets (10mm diameter)
• printed 3D parts

Download

Note: the sensor simulates an Ardumower bumper (and will be connected to the PCB bumper pin): when no motion is detected, a bumper press is simulated. Ardumower only evaluates the bumper when in driving state.

• Arduino Code
• parts for 3D printing

Wiring

Arduino Nano Vin    -- Ardumower PCB 9V out
Arduino Nano GND    -- Ardumower PCB P11 GND
Arduino Nano D8     -- Ardumower PCB P11 bumper sensor input (left/right)
Arduino Nano 5v out -- HMC5883 VCC
Arduino Nano GND    -- HMC5883 GND
Arduino Nano A4     -- HMC5883 SDA
Arduino Nano A5     -- HMC5883 SCL

Forum

https://www.ardumower.de/index.php/de/forum/sensoren/1603-sensor-fuer-das-stuetzrad-free-wheel#14955