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Building A Homebrew Robotic Lawnmower?
mmonkey writes "With the seemingly small amount of summer we get here in the UK, the last thing I want to be doing on a sunny day is mow the lawn. So I started thinking "surely a light-ish lawnmower could 'gain' a couple of motors, and suddenly be computer-controlled?". Then I started thinking about stuff like obstacle avoidance, optimum path planning, guidance system, how to get pretty-looking stripes, and I realised that it's actually a potentially complex (read: fun) thing to do. So, have any Slashdotters done this before? Did you modify an existing lawnmower or build a whole new one from scratch? What motors work best? For that matter, what type of mower works best? I know you can already get these, but that detracts from both my geek-drive and my wallet, both of which I'd prefer to keep as full as possible."
Back before everyone had the internet Popular Electronics (or one such magazine) had a couple articles on this. Lookup it up in the library, you did get the skills of searching in school, didn't you? They operated on batteries, but you could do whatever so long as your managed to power your computer.
The idea was a bunch of sensors, made up of LED senders and receivers. Mow a path around the yard, plus around any trees, and then turn the mower on. It should attempt to keep 2 sensors out of grass, and the rest (~20) in the grass.
BTW, mini-itx boards now have 12 volt power inputs, so things should be easier in many respects.
You have that kind of backwards (and wrong). The Asimovian rules are:
1. A robot must never harm a human being
2. A robot must follow a human being's orders, unless that conflicts with Rule #1
3. A robot must preserve itself, unless that conflicts with either Rule #2 or Rule #1.
I have something in common with Stephen Hawking...
There was an Autonomous Lawn Mower Competition going on earlier this month - saw it mentioned on robots.net
--The more you know, the less you know.
http://www.robotshop.se/micro/wwwrc_us/indext.htm
robocut
Might be an interesting kit.
You should read an excellent book: "Flesh and Machines: How robots will change us". It is written by Rodney Brooks. His company (iRobot) was behind Roomba design. The book explains algorithms used in it.
If I was going to do this, I would start here (I've used their products for years).
. ht ml
http://www.tri-m.com/products/engineering/index
I would use the MZ104 CPU Board. They have a Linux distro you can throw on a DiskOnChip pop that in along with a regular old 64mb laptop SODIMM and you are good to go.
You can use the IR104 i/o board to provide 20 digital inputs and 20 digital outputs. This should allow you to hook up some simple sensors as well as giving you control capability. You may also need some sort of Analog I/O board, but I would avoid this for cost reasons.
The MZ104 CPU Board also has an I2C Bus interface with linux driver support. There are a plethera of different sensors available that you can directly read from this simple two wire bus.
These products are extremely affordable, rugged, low power and small. The entire system can run off of 5VDC. You can even lower the clock rate to save power.
If you do decide to go along with this, please add a wifi card and a web cam so we can watch it mow in real-time.... (uhhh oh slashdotted lawn mower)
You could obviously do this with something that had a lot less horse power, like an 8051, HC11 or Z80, but you would have to make up a lot of custom circuitry to get the job done. I like the modular nature of the PC/104 form factor. If you do opt for something with less power, I would definately make sure it has a built-in i2c controller.
Grrrrr... don't bother me, I'm thinking.
My father did this with my help. Use a 6x6 piece of lumber (about 2 feet long) and round it (he used a jig and a table saw). Then pound two stakes into it so you can stake it to the ground when needed.
Take a self propelled motor. Attach a stiff rod to one side of the deck so that it extends past the front about 2-3 feet. Tie a rope to the rear of the mower and then to the front of this rod with some slack in the middle.
Experimentally determine a good spot along that rope to attach another rope such that when you are holding it the mower tends to turn slightly towards you. Attach that rope to the (now staked) 6x6 post in the middle of the yard. Start mower, defeat the dead man's switch (usually a bar you have to hold to keep the mower going) and let it go.
Tricky problem (left as an exercise for the reader): The rope tends to self wind up past the top of the post. Especially when mowing large tracts of land.
And yes, the neighbor kids did make fun of me at school. Saved me from mowing an extra acre though, so I didn't much care what they said.
-Adam
They make two types, an auto mower which has a 4 Ah battery and goes back to a recharging base when the batter is low and a solar mower which has a solar panel on top and doesn't need a recharging base.
From the website the automower can handle a maximum area of 1500m^2 and the solar mower 1200m^2 with the solar mower working during sunlight hours and the automower working 24 hours a day.
The boundary of where each cuts is marked by an electric loop and both have sensors to find their way around objects.
Independence? That's middle-class blasphemy. We are all dependent on one another, every soul of us on earth. G.B Shaw