Author Topic: Autonomous Lawnmower  (Read 2193 times)

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Offline arrrrgonTopic starter

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Autonomous Lawnmower
« on: February 22, 2011, 08:04:20 AM »
I would like to try to build an autonomous robotic lawnmower similar to the Lawnbott Spyder.  I'm just building it for fun, but I would like to make something that works well, is lightweight, and is quiet.  I would love to buy the Lawnbott Spyder, but $1200 is ridiculous.  Anyways, while servocity is having their sale I was curious if would be worth buying or if I need to look into some 12v motors.  My thoughts are 2 of these servos as the back wheels and 2 360 degree wheels up front.  The back 2 servos will be controlled by an atmega168 more than likely.  There will also be 2 servos spinning small blades on the bottom.  The 2 servos spinning the blades probably won't need much power, but the wheels will have to go up an appr. 30 degree hill and deal with some mole holes so they need to be decently powerful.

Any tips are appreciated.  I'm still new to this, so all help is appreciated.

Offline nickc

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Re: Autonomous Lawnmower
« Reply #1 on: February 22, 2011, 03:08:50 PM »
I think you might be underestimating your power requirements, at least for the cutter. According to their spec sheets, the motor that spins the blade on an cordless electric lawn mower is 24-60V and uses 600-1000W.  I doubt they would use a motor that big if they didn't need to.  Higher voltage will obviously keep your amperage and wire size down to something manageable but it will still generate some serious heat.  The batteries in the commercial units weigh 30 lbs or so and are usually several 12V batteries in series.
Once you add all that weight, your drive motors may need to be bigger, and the load on your steering joint will be obviously higher.
Wet grass is also pretty slippery so in addition to the torque , you will also need some good traction to make it up a 30 deg slope.
« Last Edit: February 22, 2011, 03:20:34 PM by nickc »


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