Building A Homebrew Robotic Lawnmower? 486
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."
Uhhhh (Score:4, Insightful)
Re:Uhhhh (Score:5, Funny)
Yeah, I imagine it could be an even deadlier version of Vroomba [sluggy.com].
Re:SOLAR POWER (Score:5, Funny)
Webcam would be nice. If however I r00t ur lawn mower box, and cut your geran1umz bi4tch then it is ur f4ult 4 n0t being l3et and patching your lawnmower.
I don't know if a solar panel about 2ftsquare could run an x86 with linux, and a HDD, and the necessary webcam, and 802.11b.
mmm.
You could setup webservices to allow people to subscribe to lawny, and he could drive aroun dyour whole neighbourhood, whoring itself out and 'mowing peoples lawns'
yeah.
alternatively concrete over the grass.
Re:Uhhhh (Score:5, Interesting)
But if you mowed the grass yourself, one time, and then let loose your robot to simply maintain the height with a low power electric motor and some relatively safe blades, etc.... After all, it can stay out there all damn day!
Re:Uhhhh (Score:5, Interesting)
1. A _safe_ mowing method as you describe
2. The position measurement could be done with (ultra)sonic sensors and a transmitter on the mower. Doesn't work if you have to change garden often.
3. A power and communication cable. Can be cheap because of low power requirements because of 1.
4. A tower from where the cable goes to the mower and a mechanism to ensure that the cable doesn't get in the way.
Of course there is no obstacle avoidance etc., but I would start such a project in a modest size, not with all the 1000 features which _could_ be implemented!
As I'm doing such things also (Homemade microcontroller applications are everywhere in my home), I would say that it is far better to have a little thing working than big plans for a big thing but get nothing implemented.
Re:Uhhhh (Score:5, Funny)
"ERROR...ERROR... Must kill all humans!"
It will keep the kids and neighbors away from your yard when it's mowing.
Re:Uhhhh (Score:3, Funny)
Well it could be done WITH RF. A wide angle microwave beam 1cm high and about 3 cm above the ground would do it. Oh and about 200 Kwatts.
Or overboost one of those circulating surveyors lasers, again about 3 cm over the ground. That would need less power, 200 watts should keep the grass down.
Ummm, sounds like a sheep to me (Score:5, Funny)
Re:Ummm, sounds like a sheep to me (Score:5, Funny)
Re:Uhhhh (Score:4, Informative)
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.
Re:Uhhhh (Score:3, Funny)
Re:Uhhhh (Score:5, Interesting)
Re:Uhhhh (Score:5, Insightful)
I suspect that if this worked, lawnmower manufacturers would have already done it for liability reasons. One thing about a grill is that it would probably clog for any non-trivial amount of wet grass.
Good Idea, But No. (Score:3, Insightful)
Electric sheep (Score:5, Insightful)
The underlying problem is the amount of kinetic energy you have in a spinning blade. The less kinetic energy, the safer. A spinning fishline is going to be safer than what amounts to a giant spinning knife.
Of course the reason you need the kinetic energy is so you can cut a lot of grass very quickly. With a conventional lawn mower, you can probably mow about a square meter or more per second. It cuts down on the drudgery time. But since the author is building a robot, drudgery is not an issue. So why not go slow?
I am imagining something that is very, very slow. Something that moves slowly from place to place gently cropping a tiny amount of grass at a time. In other words, an electric sheep (with apologies to Phillip K Dick). You'd calibrate the jaw strength so that it is enough to rip up a mouthful of grass easily, but not so strong it would sever a finger. You could get a nasty robot bite, but it wouldn't require a trip to the neurosurgeon.
I like the sheep idea because it leads off in more interesting directions. I'd think you'd run out of ideas for a robotized conventional mower. With the electric sheep, you can set a number of more interesting goals than having it walk a predetermined path. For starters, you could give your robot sheep a simple vision system so it could perceive the edge of your walk and touch up the edges. What would be interesting is to train it to visually recognize certain objects: it perhaps could recognize common lawn pests like dandelions or plantains and give them an extra close crop. Maybe it could retrieve the paper the paper boy threw onto the lawn and put it on your front porch. Maybe you could teach it to recognize beer cans and throw them in a recycling bin. You could make several of them and have a flock and begin to program them to interact in interesting ways.
Electric sheep - heeerrreee flossie (Score:5, Funny)
mmm electric sheep.. now where's my magnetic gloves and kneepads?
Suchetha
Re:Electric sheep (Score:3, Interesting)
What I envisioned then is a little beetle-like walking robot. It would move very slowly, but very persistently. It would have something very like mandibles with something very like a sense of taste, and would keep track where it is by means of a combination of GPS and a mesh network between dozens of them. There were other little details, like a milc
Even better... (Score:3, Informative)
Bring on the minisheep [mlode.com]!
Re:Electric sheep (Score:3, Insightful)
Use a weed whacker. (Score:3, Interesting)
Re:Uhhhh (Score:5, Informative)
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.
Re:Uhhhh (Score:4, Funny)
0. A robot must never harm humanity.
1. (revised) A robot must never harm a human being unless that conflicts with the zeroth law.
Re:Uhhhh (Score:3, Interesting)
Re:Uhhhh (Score:3, Informative)
1. A robot must never harm a human being, or through inaction allow a human being to come to harm.
The second part of that law might seem unimportant but it is just as important as the first.
Without the rest of the first law a robot could cause a human to die by 'accident'
Re:Uhhhh (Score:3, Funny)
only after he's been fired.
Kinda brings a whole new meaning to the term "terminated"...
Re:Uhhhh (Score:3, Funny)
Just for you? (Score:3, Interesting)
If you know what objects are fixed,such as pathways, bird feeders, what-not, you could build the controller from one of those old dump trucks from the 80's that let you pre-program a course by feet and angle of turn, etc. All you need to add is a bar attached to a kill switch for when the neighbors cat/kid/dog runs over to check it out.
Re:Just for you? (Score:2, Informative)
Features:
Fully automated Docking Station mower
Recharges it's power pack by itself
Departs on your schedule
Manual controller (can be used as like a traditional mower for trimming small areas)
It seems expensive, but it if you really want it (and want it now) they are availiable. Even if you don't wan't to spend that type of cash and want to build it from scratch, I'd recommend visiting company websites that develop these and download their pro
Re:Just for you? (Score:3)
Parent post: How much do you want to spend? Amazon has one for $1,799 [amazon.com]
+5 Informative?
More like -1 Redundant/Offtopic/Blind!
(Follow the link to Amazon and you'll see it's for the very same product that MMonkey says is not what he's looking for...)
Re:Just for you? (Score:3, Insightful)
How much do you think it would cost to build one of these? The pride of building one yourself can't be measured, but
Re:Just for you? (Score:5, Insightful)
Those big trak programmable toys really didn't do all that good a job of making ninety degree turns. They worked best on floors and poorly on everything else - my cousins had one and I got to play with it like once but it didn't do what it was supposed to do. It was still neat, though.
There are other problems with your plan, such as the fact that most lawns are not perfect, empty rectangles. Even if you can accurately track how far you are traveling and how far you have rotated, it's going to be a little more complex than just making a couple of right angle turns. If the problem were that simple, meaning you had a level, flat, even rectangular yard with nothing in it but grass which had already been carefully mowed not more than a day before, you wouldn't even need robotics :P
Don't build One Big Machine (Score:4, Interesting)
Good luck - I'd love to see this when you're done!
Comment removed (Score:5, Funny)
Re:Just for you? (Score:5, Insightful)
Since you are talking about your own lawn only (I assume), you actually have pretty good control over the environment. I would take a page from Rodney Brooks and from toy manufacturers:
First, as other posters have suggested, go for a weed-whacker or other smaller, less dangerous cutting design. Compensate by planning to have it running for long periods of time, like an hour daily, essentially making it a "touch-up" design, relying on manual mowing if you let the grass get away from you.
Second, basically forget about complicated, error-prone sensor packages. Use the minimal amount of sensorics you can get away with, and tailor them specifically for the task at hand. I would use one single front-and-sides bumper, set at exactly the level you want the grass to be cut.
Third, tune the environment. If you have a fence, that will work fine. For flowerbeds, ponds, cobra pits and other garden features that you don't want it to run into, set evenly spaced (rounded!) wooden pegs at the edges, so the bumper has something to run into. If you think pegs will be ugly, be creative: rocks, small fencing, whatever. It needs to be only as high as the bumper - which we alreadey set at the level of the grass.
For control, start out easy. "If we hit something, back up a few centimeters, turn a random amount and go." This can work surprisingly well if the lawn isn't too big. You can even figure out approximately how long you need to run the robot to get reasonable coverage. An added benefit of this Brownian Walk algorithm is that you really need minimal sensors - the bumper is it. You can experiment with some fancier algorithms as well - initiating a turn after some time whether you hit anything or not, for instance, or turning off altogether if you've been going forward for a very long time without hitting anything.
If you want to add some more sensorics, like shaft encoders for the wheels, you can start to play with dead reckoning and do dynaimc map generation and other funs stuff. Even with lousy precision, you can still figure out an approximate average on how much time you've been using to cut a given area, and compensate for it by going (approximately) there for some extra random walking.
As long as you can keep the unit simple, it will tend to be robust, and perhaps inexpensive enough that you can build two or three and cut the time (sorry) by quite a bit.
One important thing: make sure you have a safe, convenient way to turn the thing off. Big red button on top should do it. Have the red top be translucent and add a couple of blinking LEDs inside for that "heavy industry" look that will make you the envy of your neighbours.
And yes, BTW, I am a robot scientist, so I sort of know what I'm talking about
Re: (Score:3, Informative)
another way (Score:2, Insightful)
not very popular over there but many people do that over here in n.america
even in the long-run would be cheaper than a robot solution (unless this is a personal interest i wouldn't go ahead with it)
Re:another way (Score:3, Funny)
How About.... (Score:5, Funny)
Re:How About.... (Score:2)
didn't think of these things now did ya?
Re:How About.... (Score:3, Funny)
Re:How About.... (Score:5, Interesting)
Re:How About.... (Score:2, Informative)
Oh come on. Where the hell is he going to get sheep in England?
Joking aside the parent post need not have been joking. You can actually hire lawn care people who use sheep and goats to trim lawns. They're very effective and can be used even in the rain. They're highly water resistent, as anyone who has ever worn a proper British fisherman's sweater can attest to. Different species of grazers actually eat grass to different hights as well, so you even get that choice and th
Re:How About.... (Score:4, Funny)
Roomba + Mower (Score:3, Interesting)
Re:Roomba + Mower (Score:5, Funny)
"The Black Moomba - As dangerous to grass as it is to small pets".
He he he.
Speaking of obstance avoidance code (Score:5, Funny)
Re:Speaking of obstance avoidance code (Score:5, Funny)
MIL (Score:3, Informative)
Careful!!! (Score:2)
So you don't want to waste time missing ... (Score:5, Funny)
The best part will be you will have perfected it by the end of August.
Well.. (Score:5, Interesting)
that detracts from both my geek-drive and my wallet, both of which I'd prefer to keep as full as possible."
Well, I think your wallet's going to be drained either way. You need specialized components, software, etc for a completely automated solution. And even that's not going to be the end-all (corners, adjacent to fences, etc)
I would say start with a remote-controlled (as opposed to computer-controlled; mods, there is a difference) solution, see if you can rip apart some RC Cars [rc-car.com], take their steering equipment out, see if you can interface to them using a RC Helicopter Remote [heliguy.com] or RC Airplane Remotes [rc-airplane-world.com], connect up the servos, and perhaps sprinkle some detectors [hobbytron.net] around your lawn.
Computer controlled would be difficult, to say the least. Perhaps even a Masters level thesis or a really good undergraduate senior project. Hell, if you can make it fairly cheap and efficient, you have your own business.
Re:Well.. (Score:3, Interesting)
Ummm.... yeah (Score:5, Funny)
Re:Ummm.... yeah (Score:2)
Go plastic! (Score:5, Funny)
Re:Go plastic! (Score:3, Funny)
Re:Go plastic! (Score:3, Funny)
Search the library (Score:5, Informative)
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.
Re:Search the library (Score:2)
I remember reading those articles. A bit of googling turned up references to one of the articles: "Build the Lawn Ranger" in the June 1990 issue of Radio Electronics.
Re:Search the library (Score:3, Interesting)
Simple, effective, and does 80% of the job
Keep it Simple (Score:5, Funny)
(1) long rope
(1) stake
Step 1: Plant stake in yard
Step 2: Tie rope to stake
Step 3: Tie other end of rope to lawn mower
Step 4: Start mower.
Re:Keep it Simple (Score:2)
Re:Keep it Simple (Score:3, Informative)
Even simpler... (Score:5, Funny)
Robot Lawnmower (Score:3, Funny)
http://ltilib.sourceforge.net/doc/homepage/inde
I think the kill switch should be completely seperate from the entire system though. That way if other things fail, the kill switch can still be hit and no matter what goes on with the rest of the system it still kills the power.
Eventually, once it's all done, tweak it to see how fast you can make it work. Then make it so it can use a set of waypoints. After all that's done, enter it in the DARPA Grand Challenge and judging by last years results, you might actually have a chance!
Watch your bits (Score:5, Insightful)
Think safety and just make it an RC vehicle first (Score:4, Insightful)
Buy some help (Score:2, Funny)
The MowBot (Score:2)
Be careful! (Score:2)
I was thinking more... (Score:2)
Simple solution with no electronics involved (Score:5, Funny)
1. Get out your self-propelled "push-style" mower.
2. Measure the cutting width
3. Place a post in the center of your yard that has a diameter equal to or less than the Cutting Width / pi.
4. Tie the inner wheel of the mower to a rope that is fixed on the post.
5. Start mower at edge of yard and as it winds itself around the post, it pulls itself inward toward the center.
6. When finished, trim the edges of the yard and you're done!
Easy cheesy, and it'll make your neighbors think you're bonkers!
Re:Simple solution with no electronics involved (Score:5, Informative)
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
Next: (Score:5, Funny)
simple ... (Score:2)
My advice (Score:3, Interesting)
First, build the logic. Take an RC car and use it as a lawnmower simulator. Connect your steering/avoidance circuitry to the car and see if the car acts like you want a lawnmower to.
Lego Mindstorms? (Score:5, Interesting)
Then, if you want to do more complex things - IR rangefinding, ultrasonics etc. strap a PalmPilot, Zaurus or some other PDS with IR on it and feed the midstorms controller unit with instructions from that.
Once you have it more-or-less foolproof (and you will probably want to run a wire round the maximum extents of your lawn and have a hall-effect or similar sensor pick up on it and kill the mower if it breaches that boundary) - then you can think about attaching a proper mower body and blade to it.
Then you'll probably want to port the whole thing to an embedded Linux u-Controller, and sell it for enormous profits.
Re:Lego Mindstorms? (Score:3, Informative)
Autonomous Lawn Mower Competition (Score:5, Informative)
My dad had automated lawn mowing.. (Score:3, Funny)
Ask the USAF (Score:3, Interesting)
Don't forget (Score:3, Funny)
One already exists (Score:4, Informative)
robocut (Score:4, Informative)
robocut [robotshop.se]
Might be an interesting kit.
Fl (Score:5, Informative)
Hardware Ideas (Score:5, Informative)
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.
Simulated Prototype as a 4th year project (Score:3, Interesting)
I made a simulated prototype of a fast/simple algorithm, which was 100x (IIRC) faster than random wandering in my tests. A bit of information is here [bu.edu].
It requires that the robot know its position rather accurately, but if it's a hobby you could use differential GPS (which would add too much to the cost of a low-end commercial robot). You might look into localisation via wifi [usc.edu].
Just keep these things in mind (Score:5, Funny)
1. Make sure the robot does not take an interest in finding Sarah Conner.
2. Should you be enjoying a lazy day in the hammock while the mower does its job, and you hear some incidental music start up that sounds very 'AC/DC-ish', Get your sledgehammer or other non-complex machine based method of destruction ready.
3. Do not power the robot with alcohol. Take extra care not to power the robot with malt liquors such as 'Olde Fortran', lest your robot develope a penchant for petty theft.
4. klaatu barada nikto
5. Consider brushing up on Asimov's laws of robotics, just so's you get them right.
Aside from Asimov's laws... (Score:3, Funny)
last thing i want to do is mow the lawn (Score:3, Funny)
...
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. By the time you get that thing built you'll need a bush hog to cut down the long grass.
So the first thing you want to do on a sunny day during your short summer is build a complex lawn mower? It sounds to me like a priority thing rather than a summer thing. I should insert a comment about "true geek" here, but this reference should suffice.
Here's My Suggestion (Score:3, Funny)
Mine (Score:4, Interesting)
How about grass-cutting ants? :) (Score:3, Funny)
Just buy a goat (Score:3, Funny)
1960's Solution.. (Score:3, Interesting)
The diameter of the drum should be a bit less than the width of the mowers rotors..
Or, just buy a goat..
Re:Simpler solution. (Score:3, Funny)
uh oh... [esmas.com]
Re:Already solved. (Score:2, Funny)
What if you live in an all white neighborhood and don't have any slaves?
Re:so let me get this straight... (Score:4, Insightful)
Re:so let me get this straight... (Score:2)
Re:Kill Switch (Score:2)
Once the unit detects enough tilt against the horizontal, it cuts off. Redundancy is also available from underbelly photo sensor, assuming you keep the cutting bay dark in normal operations.