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Robotics Hardware

Building A Homebrew Robotic Lawnmower? 486

Posted by simoniker
from the rotors-of-death dept.
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."
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Building A Homebrew Robotic Lawnmower?

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  • Uhhhh (Score:4, Insightful)

    by Anonymous Coward on Wednesday June 23, 2004 @08:18PM (#9513570)
    I'd make sure its plenty safe. I'm not concerned about you, but picture a mis-programmed robotic lawnmower chasing the neighbors dog, or worse, trying to run over a child... :|
    • Re:Uhhhh (Score:5, Funny)

      by Penguinshit (591885) on Wednesday June 23, 2004 @08:21PM (#9513581) Homepage Journal

      Yeah, I imagine it could be an even deadlier version of Vroomba [sluggy.com].

    • Re:Uhhhh (Score:5, Interesting)

      by Eiki (713952) on Wednesday June 23, 2004 @08:32PM (#9513658) Homepage
      The safe way to do it is to have the thing run with very low power, and just nibble at the lawn, but do it all day. The big gas engine on the top of your push mower is really for the convenience of the operator, so that he can mow tall grass without stalling the thing or slowing down.

      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)

        by sploxx (622853) on Wednesday June 23, 2004 @08:40PM (#9513727)
        Yes, I would implement the following:

        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)

          by Lumpy (12016) on Thursday June 24, 2004 @10:22AM (#9517835) Homepage
          I dont care how it is built. all home brew mowers need a speech synthesiser and a loudspeaker that constantly says....

          "ERROR...ERROR... Must kill all humans!"

          It will keep the kids and neighbors away from your yard when it's mowing.
      • by rben (542324) on Wednesday June 23, 2004 @10:23PM (#9514421) Homepage
        Hmmm, sheep runs on the grass it eats, nibbles all day and is not particularly noisy. Better still, unless it is a Ram, it's unlikely to chase the neighbors. :)
      • Re:Uhhhh (Score:4, Informative)

        by farmerj (566229) on Thursday June 24, 2004 @06:21AM (#9516317)
        Husqvarna [husqvarna.com] already make mowers exactly like you describe and have done so for at lest the last 5 years.

        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:5, Interesting)

      by k4_pacific (736911) <k4_pacific AT yahoo DOT com> on Wednesday June 23, 2004 @08:35PM (#9513689) Homepage Journal
      Suppose you made a grill for the bottom of the mower deck similar to that which covers the blades of an electric razor. This would allow the blades of grass to reach the rotating blades while keeping fingers and toes safe. Perhaps finding one of those big furnace registers like you see in old houses would be the way to go.

      • Re:Uhhhh (Score:5, Insightful)

        by upsidedown_duck (788782) on Wednesday June 23, 2004 @08:50PM (#9513810)
        Suppose you made a grill for the bottom of the mower deck similar to that which covers the blades of an electric razor.

        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)

        by Anonymous Coward
        Have you ever used an electric razor? One pass won't do the job. Hell, three or four passes and you're still looking at a few stray hairs. Besides, in order to be remotely effective, the holes would need to be at least the size of a child's fingers.
      • Electric sheep (Score:5, Insightful)

        by hey! (33014) on Wednesday June 23, 2004 @09:57PM (#9514257) Homepage Journal
        That's an interesting idea, but I doubt you could get the grill fine enough to prevent fingers from entering without.

        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.

    • Use a weed whacker. (Score:3, Interesting)

      by Darth Muffin (781947)
      Seriously, if you go ahead with this, don't use a regular metal mower blade. Use something like a weed whacker--a nylon string. Coverage is far less and speed is less, but speed shouldn't matter in this application. So what if it has to make 4x as many passes...
  • Just for you? (Score:3, Interesting)

    by Johnathon_Dough (719310) on Wednesday June 23, 2004 @08:20PM (#9513573)
    If this is something that is for you only, and not for sale, then I would think it would be easy.

    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)

      by Grant29 (701796) *
      How much do you want to spend? Amazon has one for $1,799 [amazon.com]

      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

      • Original article: 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.

        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)

          by Grant29 (701796) *
          I realized the redundancy of the link, but I was merely pointing out the price and availiablity. This is a product that I have not tracked pricing for, so I'm not sure if $1,799 is average, high, or low. I also do not know if this is the type of product that has had price reductions over time. I assume that as time goes on and more competitors emerge that the prices will fall even more.

          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)

      by drinkypoo (153816) <martin.espinoza@gmail.com> on Wednesday June 23, 2004 @08:33PM (#9513677) Homepage Journal
      While that is not an entirely preposterous proposition, I have to wonder if you are a troll because your comment seems to almost (?) deliberately ignore all of the complications in the problem. While the goal of mowing one's lawn is to create an orderly and even surface, at its best it will always be an irregular surface in terms of height and traction. A wheeled or even tracked robot will tend to wander when on a hill and there is no guarantee that your motive devices are accomplishing as much as you would like them to. This is all mounted to a chassis which will necessarily absorb a certain amount of shock because the blade will end up hitting things which it was not designed to cut. There are other problems but these are some or the more obvious ones.

      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

    • by kraksmokr (216277) on Wednesday June 23, 2004 @08:41PM (#9513737) Journal
      If you really want to be different consider an autonomous swarm of mowing machines. The guts of a Roomba would be a good starting point! I'd like to see a self-organizing mesh network created by the mobile mowing agents.

      Good luck - I'd love to see this when you're done!
      • by 404 Clue Not Found (763556) on Wednesday June 23, 2004 @09:41PM (#9514149)
        Vacuuming is one thing, but do you really want a lawn mowed in the erratic pattern that Roombas use (some sort of random spiraling pattern designed to cover all areas of a room)? It would be Bad Lawn Day, every day.

        Having an army of them do it simultaneously probably wouldn't be any better. Your lawn would look like it was cut by a horde of drunken, psychotic Zen masters competing over the same sand garden.
    • Re:Just for you? (Score:5, Insightful)

      by JanneM (7445) on Wednesday June 23, 2004 @10:18PM (#9514392) Homepage
      I think using "Big AI" like that would be the wrong approach, really. It is very difficult to get right and brittle to unexpected change.

      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:Just for you? (Score:3, Informative)

        by big tex (15917)
        Another idea for the 'fence' - it can be an electronic fence, kind of like electronic dog collars.

        The supermarket near where I went to college installed this electric fence for the shopping carts, where one of the wheels would lock up when it sensed that the line was crossed.

        So, bury some wire, and off you go.

  • another way (Score:2, Insightful)

    by Coneasfast (690509)
    this is off-topic, but you could ask the neighbours kids, they usually will do it for a couple of quid.

    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)
  • by dirkdidit (550955) on Wednesday June 23, 2004 @08:21PM (#9513586) Homepage
    How about a goat? Maybe a sheep? Set one of those bad boys loose and you'll have yourself a short lawn. Obstacle avoidance and everything built right in.
    • well what happens when the goat or sheep starts crapping all over your lawn? thats just more work. and you would need to fence it too to prevent the animal from escaping.

      didn't think of these things now did ya? :)
    • Re:How About.... (Score:5, Interesting)

      by mangu (126918) on Wednesday June 23, 2004 @08:32PM (#9513661)
      I read somewhere that in Scotland they use geese for the same purpose. You get a free trespasser alarm, since neither a goat or sheep will care about who enters the space, but a goose will attack first, then make a loud noise, and ask questions later.
    • Re:How About.... (Score:2, Informative)

      by kfg (145172)
      How about a goat? Maybe a sheep?

      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
    • by bluesnowmonkey (148168) on Wednesday June 23, 2004 @08:50PM (#9513811)
      Or better yet, some sort of rental service, or Rent-A-Goat, if you will. Ooh ooh patent patent!
  • Roomba + Mower (Score:3, Interesting)

    by dracken (453199) on Wednesday June 23, 2004 @08:22PM (#9513591) Homepage
    How about some duct tape job of roomba [roombavac.com] and a lawn mower ? You get obstacle avoidance and area coverage for free. You can even come up with interesting names like "Rower" or "Moomba" :^)
  • by raddan (519638) on Wednesday June 23, 2004 @08:25PM (#9513611)
    Make sure to code-in police avoidance for when your unattended lawnmower runs over your neighbor's feet while he sleeps in his lawn chair. On the bright side, you might end up with fewer cats hanging around the yard...
  • MIL (Score:3, Informative)

    by Grieveq (589084) on Wednesday June 23, 2004 @08:27PM (#9513615)
    The University of Florida's Machine Intelligence Lab did the research 7-10 years ago. http://mil.ufl.edu/
  • This is no Roomba. Remember, the difference between a lawn mower and a vacuum cleaner is the *sharp* blades!
  • by bloxnet (637785) on Wednesday June 23, 2004 @08:29PM (#9513634)
    ...the sunny days during your short summer. To correct this, you will spend time indoors hacking away and making a homebrew robotic lawnmower.

    The best part will be you will have perfected it by the end of August.

  • Well.. (Score:5, Interesting)

    by herrvinny (698679) on Wednesday June 23, 2004 @08:29PM (#9513635)
    My first reaction was, "Well, you linked to what looks like a small business site, so either that site's going down or the hosting fees with bankrupt the company". But I digress.

    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)

      by drinkypoo (153816)
      Ripping apart radio controlled cars to get pieces for a lawn mower is like ripping apart go-karts to get pieces for a dump truck. Only the largest radio controlled cars are at all along the right scale and those things cost as much as a robotic lawn mower, no joke - I'm talking 1/4 scale here. Even 1/8 scale is pretty small, it's about the size of a lawn mower but designed for low weight and usually equipped with a 0.15 or 0.21 cubic inch nitroethylene motor. Those little .15ci two strokes can put out a hor
  • by cr@ckwhore (165454) on Wednesday June 23, 2004 @08:30PM (#9513643) Homepage
    So, let me get this straight ... your solution to avoid an afternoon of mowing the lawn is to spend several months automating your lawn mower?? Sweet.

  • Go plastic! (Score:5, Funny)

    by k4_pacific (736911) <k4_pacific AT yahoo DOT com> on Wednesday June 23, 2004 @08:31PM (#9513648) Homepage Journal
    Have you considered artificial grass? It comes in a variety of colors and never needs mowing. Mine is "Misty River Green". With the optional circulated brine heating system, you can have a lush green lawn all year around, even when your neighbors' lawns are covered in snow. I recommend GrassCo brand Artificial Lawn Carpeting with its realistic texture and patented Flow-Thru (TM) drainage system. As a homeowner and lawn care enthusiast, I can assure you, GrassCo brand artificial turf is the only way to go.
  • Search the library (Score:5, Informative)

    by bluGill (862) on Wednesday June 23, 2004 @08:31PM (#9513649)

    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.

    • Popular Electronics (or one such magazine) had a couple articles on this.

      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.
  • by Anonymous Coward on Wednesday June 23, 2004 @08:31PM (#9513650)
    Materials: (1) Self Propelled Lawn Mower
    (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.
  • by dangerz (540904) <stuff&tildastudios,net> on Wednesday June 23, 2004 @08:31PM (#9513656) Homepage
    Try looking at something like this:

    http://ltilib.sourceforge.net/doc/homepage/index .s html

    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)

    by Stonefish (210962) on Wednesday June 23, 2004 @08:31PM (#9513657)
    A friend's neighbour decided to build a ride on lawnmover. Problems arose when decided to take the mower for a test drive. The Blade guard was off and halfway through the test the seat collasped and he had to put his foot down. Needless to say he gets around really well on his new leg.
  • by Radical Rad (138892) on Wednesday June 23, 2004 @08:32PM (#9513663) Homepage
    It sounded like you want to make it autonomous but I think you should just try to make it telerobotically controlled at first to get the kinks out of your hardware design, adding some H bridges, sensors, and a laptop later on. It might be safer to build onto a store bought mower with a clutch that can disengage the blade. That's uncommon though and you probably won't find one at a garage sale. So the cheapest and maybe safest route would be to make a mower using the weed whacker concept of a spinning spool of heavy nylon cord. If an accident happens at least you won't lose an arm.
  • by Anonymous Coward
    Too bad you guys don't have Mexicans over there in the UK. Did you check Ebay to see what a good used Mexican is selling for? Even the used ones can mow lawns fairly well.
  • You could get some ideas from this [21stcentury.co.uk] one.
  • Let this fine film [imdb.com] be an instructional video for what could go horribly wrong.
  • by JiffyJeff (693994) on Wednesday June 23, 2004 @08:39PM (#9513723)
    My dad did this just to get a chuckle out of the neighbors:

    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!
    • 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
  • Next: (Score:5, Funny)

    by omarius (52253) <<moc.gnorwlla> <ta> <ramo>> on Wednesday June 23, 2004 @08:40PM (#9513728) Homepage Journal
    AskSlashdot: Building a homebrew prosthetic foot?
  • Why not dismantle one of those robotic hoovers and attatch it to a black and decker flymo?
  • My advice (Score:3, Interesting)

    by Call Me Black Cloud (616282) on Wednesday June 23, 2004 @08:46PM (#9513774)

    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)

    by ikekrull (59661) on Wednesday June 23, 2004 @08:50PM (#9513804) Homepage
    First, get yourself a couple of Lego Mindstorms kits (so you have all the motors ans sensors you might require), and work up a useful collision-avoidin/path-cutting bot in your living room. maybe put it on a big sheet of paper, arm it with a felt-tip-pen, and tweak it's path-cutting algorithms like that.

    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.

  • by Tekmage (17375) on Wednesday June 23, 2004 @08:50PM (#9513809) Homepage
    There was an Autonomous Lawn Mower Competition [ion.org] going on earlier this month - saw it mentioned on robots.net [robots.net]
  • by NanoGator (522640) on Wednesday June 23, 2004 @09:02PM (#9513883) Homepage Journal
    ... until I moved out.
  • Ask the USAF (Score:3, Interesting)

    by john_smith_45678 (607592) on Wednesday June 23, 2004 @09:03PM (#9513888) Journal
    Maybe you could attach a mower to one of these [yahoo.com].
  • by MrYotsuya (27522) on Wednesday June 23, 2004 @09:10PM (#9513921)
    Don't forget to add some evil Battlebot settings!
  • One already exists (Score:4, Informative)

    by helix400 (558178) on Wednesday June 23, 2004 @09:12PM (#9513930) Journal
    Slashdot editor Pudge mentioned he uses a robotic mower in a recent journal entry [slashdot.org]. If you're too lazy to read it, the link to the mower is here http://www.robomower.com/robomo.htm [robomower.com].
  • robocut (Score:4, Informative)

    by priich (732295) on Wednesday June 23, 2004 @09:16PM (#9513956)
    http://www.robotshop.se/micro/wwwrc_us/indext.htm
    robocut [robotshop.se]

    Might be an interesting kit.
  • Fl (Score:5, Informative)

    by krokodil (110356) on Wednesday June 23, 2004 @09:30PM (#9514053) Homepage
    You should read an excellent book: "Flesh and Machines: How robots will change us" [amazon.com]. It is written by Rodney Brooks. His company (iRobot) was behind Roomba design. The book explains algorithms used in it.
  • Hardware Ideas (Score:5, Informative)

    by Eisenfaust (231128) on Wednesday June 23, 2004 @09:34PM (#9514085) Homepage
    If I was going to do this, I would start here (I've used their products for years).

    http://www.tri-m.com/products/engineering/index. ht ml

    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.
  • by Roger_Wilco (138600) on Wednesday June 23, 2004 @09:36PM (#9514102) Homepage

    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].

  • by Darth_brooks (180756) <clipper377NO@SPAMgmail.com> on Wednesday June 23, 2004 @09:39PM (#9514129) Homepage
    points to consider:

    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.
  • by unfortunateson (527551) on Wednesday June 23, 2004 @10:08PM (#9514322) Journal
    Don't forget to make sure it's not programmed to go back in time and kill your mother. She's not named Sarah Connor, is she?
  • by jdkane (588293) on Wednesday June 23, 2004 @10:09PM (#9514329)
    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.
    ...
    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.

  • by telstar (236404) on Wednesday June 23, 2004 @10:45PM (#9514538)
    Here's [it.uu.se] what I'd recommend. It'll cost you about $10 per mow, but it's worlds easier than building your robomower.
  • Mine (Score:4, Interesting)

    by EvilMidnightBomber (778018) on Thursday June 24, 2004 @12:38AM (#9515162) Homepage
    Pic [earthlink.net] Started mine about 11 years ago. The mechanical platform was a roboticized Toro 4hp mulcher using a permanent magnet motor driven backwards to generate power for two beefy wheel drive servos and the electronics. Fully autonomous. Narrow beam ultrasound sweeping the forward path for semi-coherent vision. No external environment markers used except where there aren't any objects to range off of for 20 odd feet. You walk it through the lawn once and it makes an internal map of the environment and the path you chose it to follow. Then, just plop it down and hit the start button next time. Works infinitely more efficiently than the commercial attempts at *cough* autonomous algorithms the crux of which is which way to turn after boffing into the perimeter wire or an obstacle. Rev. 2 is going to go battery-powered for safety and you'll have to "show' it where the charging station is. Wish I'd had money to take it commercial.
  • by antdude (79039) on Thursday June 24, 2004 @01:27AM (#9515421) Homepage Journal
    See here [ibiblio.org]. [grin] ;)
  • by Zog The Undeniable (632031) on Thursday June 24, 2004 @04:00AM (#9515939)
    And no, I'm not going to include a link in this reply, because /. readers tend not to trust URLs with "goat" in them ;-)
  • 1960's Solution.. (Score:3, Interesting)

    by adeyadey (678765) on Thursday June 24, 2004 @09:01AM (#9517025) Journal
    I remember reading an old magazine 60's("Radio Constructor") that featured a solution to this- a guy had a circular lawn & wanted to automatically mow it - how did he do it? Complex electronics? no. He put a large oil drum in the center, and attatched the petrol mower by a long rope with a lenth the radius of the circle, wound around the drum. The mower is started, and as it unwinds mows a spiral pattern - then mows another spiral coming in! Bloke goes and has beer, and comes back just in time to switch the mower off as it hits the center.

    The diameter of the drum should be a bit less than the width of the mowers rotors..

    Or, just buy a goat.. :-)

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