Let's Make Robots!

LawnBott

autonomous lawn mower

Well I have finally made some time this winter to return to my lawn mower project.. This has plagued me for a few years, trying to figure out the buried wire fence .. Although I have certainly learned tons I by no means claim to know all about this buried wire fence... The circuit that I settled on after making so many that I can't count and spending endless hours and money on different ideas.. Sorry was going off on a rant there.. Anyway the circuit that is shown in the videos is a fairly simple 38Khz square wave being sent out onto the wire. and for a receiver I am using a L/C tank circuit and running that through a op-amp with adjustable gain and finally putting that signal through a peak detector circuit into an analog port on the Arduino.. I will try and add a basic schematic/drawing of the circuit with the components labeled as time permits.. The first video is of lawnbott in random avoidance mode, the second is of wire following mode.. I will try and keep up on the progress as I complete but at the moment listed below is the sensors I have implemented: - buried wire fence detectors - right and left bumpers - battery level indicator - wheel encoders - mower blade motor encoder - mower blade motor current detector Stay tuned..

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I've been myself working (for a long time as well!) on a similar project (version 6 !) called La Poulette  with more details in french

This time I increased the burried wire frequency to 48 Khz, I thought I could get a more effective detection and It wotks well so I' ll have to reduce the sensistivity.

Be aware that moving a robot on the lawn needs quite a lot of power and larger wheels.

I now working on an IR/US  docking station. To do that I've got to improve the accuracy of the steering mostly based on wheels-encoders (only 24 pulses/rotation)