Robotic lawnmowers are a familiar sight in German gardens. What is less well known is that home gardeners can build a robot lawn mower themselves. If you have large lawns to mow, you can use ready-made kits from specialist shops. Tinkerers can achieve useful results for small green areas with inexpensive components that can be purchased everywhere. This overview will familiarize you with the basic components for building your own.
A robot lawn mower consists of many different components
Basic components for a robot lawn mower
Gardeners with the heart of a genius software developer have developed a lawn mower robot for the average ornamental garden. The device provides a WLAN access point so that you can use your smartphone for manual control. The basic components for self-construction are summarized below:
- Frame: Square tubes welded in a triangular shape for 2 drive wheels and 1 front steering wheel
- Mowing disc as a platform for wheels and battery: disc or triangular star of a chainsaw with 3 carpet knives
- Accumulator: car battery with 36Ah
- Traction motors: automotive wiper motors
- Drive wheels: removed from the old petrol lawn mower
- Mower motor: Radiator fan motor of a VW Passat or comparable car model
To ensure that the lawn mower robot makes straight tracks, it is also equipped with a 3-axis compass. The core is a Raspberry Board Pi as the control center with a circuit board as the power unit.
Tips for mowing field limitation
So that the lawn mower robot later limits its work to the lawn and does not drive over your flower beds, it is equipped with antennas for the mowing area limitation. To do this, lay a simple 1 mm wire about 20 cm from the edge of the lawn, just under the turf.
Connect both ends of the cable to a transmitter circuit board. If the lawn mower robot is in operation, it is continuously transmitted from here at a frequency of 20 kHz. The robot's DCF77 antennas can receive this frequency. Installing these two aerials at a 45-degree angle on the left and right in front of the front axle ensures the best possible reception.
The robotic lawnmower can be stopped and turned around as soon as it moves towards the edge of the lawn and drives the front antennas over the previously laid line.
tips
Most DIY robotic lawn mower projects are in their infancy or expensive. Resourceful hobbyists have decided to convert their proven petrol lawn mower into a self-propelled one without further ado. This can be achieved with the help of DC geared motors and adequate RC electronics at comparatively low cost and in a fraction of the time.