Lawn Grazer

An Autonomous Electric Grass Mower

I love Disney World. They have some of the neatest projects anywhere. One that looked like it would be a lot of fun (and possibly save me some work and time) was located behind Spaceship Earth in Epcot. Presented by WeedEater, it is a self contained, free roaming electric lawnmower. Even though they do not mention it on their web site, as I understand, this unit is now available for sale – in fact I read somewhere that the CIA is using them around their facilities.

My concept is a unit approximately 12" wide by 24" long and 6" high. The top would be covered by two solar panels generating 8 watts in bright sunlight. This power would be used to power the unit and recharge gel-cell batteries that would be used when the sun was blocked by intermittent clouds. There will be two independent drive wheels, and a third "trailing" wheel to provide balance. Cutting would be done by two circular cutters ~ 6" in diameter. With a slight overlap, Grazer would cut 10" in a pass. Onboard processing would be handled by a MicroChip 16F877 micro-controller.

The basic software would recognize day, and randomly head out into the yard. Picking a spot, the unit would then cut a 10’ by 10’ square. The next pass would move in 8" and so on until the area had been cut. Grazer would then move onto another spot and start cutting again.

Sensors would detect an obstacle in the path, to which Grazer would shorten that side of the square. Boundaries would be set by using a similar concept as the "underground dog fence" - where a wire would be place around the perimeter of the cutting area. A low wattage radio signal would be broadcast by this wire. A receiver on board Grazer would sense the "wire" and turn away.

Other sensors are to include a grass wetness (mowing wet grass is never fun), rain sensor, low power, and anti-theft. Off hours would be spent in a weather-proof recharging "home".

It is my hope that the continually mowing of random 10’ squares during daylight hours would cover the yard in a reasonable number of days. Hey – if one does not work, maybe I will build a herd of Grazers!

I have received all the parts needed to start construction. The basic platform has been constructed, and major functions have been flow charted. I fear that other projects have take precedent over Lawn Grazer and there is currently no projected operation date for this project.

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