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Thread: "ALMower" [was: Robotic Lawn Mower]

  1. #21
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    Re: Robotic Lawn Mower

    One system I heard that could is the electric dog fence. Anyone got a schematic for it?

  2. #22
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    Re: Robotic Lawn Mower

    I worked up numbers/graphs on those motors being offered in the catalog. I should go dig that graph up, I posted it in one of the threads here. Maybe get Alex or Andrew to add it to the catalog page...

    Those are pretty cool motors, but they'll be a lot less cool carrying around the weight of a 30Ah gel-cell. The total weight on those motors should probably be kept under ~40lbs/18kg. I think you'll have traction issues with those tires on a lawn, although I don't have that specific tire to make the call for sure.

    Now that Robocut that you link is doing some pretty cool stuff with its design mechanically. At first blush it looks like it's using drill motors. Great torque good runtime. My Hitachi Lithium will run nearly 3hrs drilling "normal" holes. My Hitachi NiMH actually had even better runtime.

    If *I* were building this project, I'd go down to Harbor Freight (might have a challenge not being in the US, but you could contact them on their website, harborfreight.com or find someone to ship to you) and pick up a few of their cheapie nicad cordless drills. Rip the battery packs out and toss 'em in the gar... in the hazardous waste recycling bin, and pick up some NiMH packs. The 10Ah batteries from Tenergy would be perfect. I would yank the motors and gearboxes out of those drills, and put them on the ammeter to make sure they'd run off of a Syren motor controller, which I suspect they will. (The DeWalt drill motors are just over the rating, so those should be under it).

    For wheels, I'd use a design similar to theirs, only I'd go on the cheap and use two or three per side old bicycle chainrings. Those would bite nice. I'd build the frame out of lexan or other poly-carb plastic with corner bolsters similar to the ones on the robocut. My cutter blade would be chain driven from one of the drill motors without the gearbox, because adjusting torque and speed would be cheap and easy by just replacing the cogs. 3500 RPM should be a no brainer if you're not trying to cut little trees or something.


    That's my whiteboard design. If I had a lawn, I'd probably build it.

    Once we all come to some consensus, we can start putting together a shopping list.
    I Void Warranties�

  3. #23
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    Re: Robotic Lawn Mower

    Quote Originally Posted by revoltage View Post
    One system I heard that could is the electric dog fence. Anyone got a schematic for it?
    When I want to understand already existing technology, I do a patent search. A patent is required to "make plain to someone reasonably skilled in the art".

    http://www.patentgenius.com/patent/7081821.html
    I Void Warranties�

  4. #24
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    Re: Robotic Lawn Mower

    Quote Originally Posted by revoltage View Post
    Hmmm...
    I'm a bit confused now what to do...
    The motor I was planning to used to cut the grass is also a dc one. I planned to use 250 square metres of the available flat lawn area to carry out the test. In my university so far no one has ever done a robotic lawn mower and it is also not at sales at hardware stores.
    I have come across a link to another website but I am a bit confused about it too due to my lack of technical knowledge. I guess you all experienced robotics experimenters would find it simple. Could you please check it out and give me some feedback

    http://www.robotshop.se/micro/wwwrc_us/indext.htm

    From what I see from this website I guess the parallax motor mount wheel kit would work. Please give me some clue guyz
    Thanks you all for your generous help
    Well, I certainly didn't mean to confuse you. The example from my earlier post was just that, an example! I don't want you to be influenced by my perceptions of what a mower should be, rather you need to envision what your mower should be and work out the engineering from the ground up! The example should give you an idea of the issues to work out, but by no means assume that you have to build it that way. I for one would rather see you "think outside the box" and develop something truly unique
    The link to the robotshop mower you provided shows an elegant solution to the weight to battery issue and the use of very thin "low drag" all terrain wheels. It looks like it would fall into your 11kg goal. Someone was thinking outside the box on that one.
    As you work out your design ideas feel free to keep asking questions!!!

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    Re: Robotic Lawn Mower

    Quote Originally Posted by Adrenalynn View Post
    When I want to understand already existing technology, I do a patent search. A patent is required to "make plain to someone reasonably skilled in the art".

    http://www.patentgenius.com
    Great Link !!!!!!!!!!!!!!!!!!!

  7. #27
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    Re: Robotic Lawn Mower

    Harborfreight does not ship to my country. So do you think that the parallax motor can be used so that I can make a robot like robotcut?
    Last edited by revoltage; 09-07-2008 at 04:21 AM.

  8. #28
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    Re: Robotic Lawn Mower

    If by the parallax motors your talking about the new right and left hand motors? Then...the short answer is yes. I've had students sit on vivian, my robot, and she can move them. She uses 4 of them and direct drive. The motors do suck amps though, especially when you load them with weight. Vivian weighs about 25-30 lbs and can run for about 20 minutes continuously on a five amp hour battery.

    You are planning on using a mulching blade right?

    Here is the link to vivian...she started out as gepetto II

    http://forums.trossenrobotics.com/sh...?t=1439&page=2


    Hope this helps.

    DB

  9. #29
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    Re: Robotic Lawn Mower

    It's for absolutely dead certain those wheels will be worthless for that application - I had an opportunity to see 'em today.
    I Void Warranties�

  10. #30
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    Re: Robotic Lawn Mower

    Yep exactly I'm going to use mulching blades and two rear wheels (thus two motors) and a front castor wheel. For the PIC 16F877A I'm going to use an olimex PIC-P40 proto board

    http://olimex.com/dev/index.html

    Then one rear and one front bumpsensors. Then a dc motor (I don't know which one yet) for the mulching blades. Also a tilt sensor so that when somebody lift the mower during it's operation the baldes stop rotating.

    Then there is this perimeter wire thing which I have not yet manage to create a schematic for it

    And yes for the battery I'll use Adenalynn's link

    http://www.tenergybattery.com/index....id=27&vmcchk=1

    All this plus the weight of aluminium casing it should be less than 10 kg I think

    So it is final everyone agrees that I can buy the parallax motor mount &wheel kit with position controller so that the robot can reverse,stop and move forward?
    Last edited by revoltage; 08-08-2008 at 09:04 AM.

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