Basic components for a robot lawn mower
Gardeners who have the heart of an ingenious software developer have developed a robot lawn mower for the average ornamental garden. The device provides a WLAN access point so that you can use your smartphone for manual control. We summarize the basic components for self-construction below:
- Frame: square tubes in triangular shape welded for 2 drive wheels and 1 front steering wheel
- Mower disc as a platform for wheels and battery: disc or triangular star of a chainsaw with 3 box cutters
- Accumulator: car battery with 36Ah
- Drive motors: car windshield wiper motors
- Drive wheels: removed from the old petrol lawnmower
- Mower motor: Cooling fan motor of a VW Passat or comparable car model
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So that the lawnmower robot can draw straight lines, it is also equipped with a 3-axis compass. The centerpiece is a Raspberry Board Pi as a control center with a circuit board as a power unit.
Tips for limiting the mowing area
So that the robot lawn mower will later limit its work to the lawn and not drive over your flower beds, it is equipped with antennas for the mowing area delimitation. For this purpose, lay a simple line with a 1 mm cross-section about 20 cm from the edge of the lawn directly under the sward.
Connect the two ends of the cable to a transmitter board. If the robot lawn mower is in operation, it is sent continuously from here at a frequency of 20 kHz. The DCF77 antennas of the robot can receive this frequency. The installation of these two antennas at a 45-degree angle to 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 its front antennas over the previously laid cable.
Most of the projects for DIY lawn mower robots are still in their infancy or involve high costs. Resourceful hobbyists have decided to quickly convert their proven petrol lawnmower into a self-propelled machine. This is achieved with the help of DC gear motors and adequate RC electronics at comparatively low costs and in a fraction of the time.