I built this fully automatic mower that cuts your lawn while you sit under a shade tree relaxing having a nice cold drink.
I saw a concept similar to this back in 1961. It was published in April 1961 Radio Electronics by Gordon Carlson, I tried to build it around 1964 when I was just out of school but was having problems with the circuit. I reached out and contacted Mr. Carlson at that time and Mr. Carlson suggested that I could design a much better circuit using the more modern components in electronics that were coming out at that time. I would have never dreamed how deeply I would get involved in electronics. Over the many years sense that article came out in 1961 many people have tried their hand to capture just the moment I was experiencing sitting under that shade tree having a cold drink. One company came close, building over 50 units designed as robotic mowers only, not to be ridden on. That company eventually turned to a more profitable venture in manufacturing components for fiber optics which was the start of faster communication at that time. Their mower had a 36 in mowing deck and they did not use Mr. Carlson circuit, they too designed their own circuitry.
There are many robotic mowers out on the market that operate by installing a wire all the way around the perimeter of the area to be mowed. The mower then attempts to cut the grass at a random 15 degree angle coming off the installed perimeter wire, leaving many areas uncut. This type of robotic mowers is just for cutting grass and cannot be used for many of the other chores that are required around the yard. Radio controlled mowers were also tried but required constant observation while they mow. The GPS global positioning systems that large farmers use are too expensive and do not have the accuracy of ¼ of an inch like what I now have developed.
I wanted a riding mower which I could use as an automatic mower with little modification but in turn could be quickly changed back in a matter of minutes to be used as a regular mower. The first mower I used was a john deer 212 with a 48 in deck that was in the 1970. The new mower is a john deer X530 with a 54 in cut which also has power steering and cruise control. This mower requires less wire to be put down and a much smaller steering motor. This newer mower traces the wire without deviating more than one-quarter of an inch from previous runs.
The wire is energized with small frequency current which sets up an electromagnetic field around it. Coils mounted in a 1/ ½ in PVC pipe mounted in front of the mower seek out that electromagnetic field and send that information to the control box which in turn moves the steering wheel. Feelers mounted on the front of the mower will stop the unit if they sense an obstacle such as toys or other objects in its path, if the signal is lost or deviates more than a few inches from the wire that will also stop the mower. After traveling 4 ½ miles this mower comes to a stop in front of its storage shed. The sensors then can be removed within a couple of minutes and be driven off to be used for other operations.
One more amazing thing is the mower puts its own wire in the ground after the first wire is put in, you will be able to see this on our blog it's amazing.
If someone approached me to buy my design I would gladly consider it and possible be a consultant in such a venture. Most mowers could be converted using a system lake this for around $400.00. Mean time I will be setting under that shade tree, reading and having a cold one and watching my lawn mower do the entire work.
Written by Doug Heffron and Son.
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Click here to read the Gordon Carlson artical in Radio Electronics,