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Thread: OSCAR

  1. #1
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    OSCAR

    I've been talking for awhile about OSCAR off and on. I'm going to start fleshing him out as I move forward here.

    OSCAR is an autonomous garbage can for events - he was spawned during the Maker Faire when we had to go searching for a refuse bin. "Gee, you'd think here the garbage can would come find you!"

    He will drive around, ask for garbage, when he full, he'll deposit it in a full size dumpster and return to his patrol route.

    OSCAR will be driven by two large (160A stall @ 36v) cart motors. The lifter design is still up for grabs, but my friend and I are starting to nail it down - that's really his piece, where base, sensors, brains, programming are mine. He will likely turn with that big bad Vantec SSP105 servo.

    Motor controllers are 2x Robot Solutions 160A dual channel controllers, and battery today is 6x lawn tractor batteries (spillable), two sets of three in series on each "side" - but it's planned that we'll go to gel-cells once the base is proven out.

    There's a couple additions we've come up with, we'll see how many survive. One's an animatronic "driver" on the back, randomly turning a steering wheel and banging on the horn. The second is an animatronic Oscar The Grouch in a trashcan on a pedastal, singing the "I love trash" song, asking people for garbage, and yelling at them to "SCRAM!"

    I had originally welded-up something like a battlebot base for it, but then happened upon a gorgeously designed (and on sale!) garden cart at Lowes. 1200lb rating, bright yellow, sides that can be rolled down and/or removed entirely. 12" wheels. It's pretty awesome!

    So I'll start posting some photos as things progress. The biggest concern today is figuring out WHERE to construct him. Without the lifter and trashcan he's already approaching several hundred pounds (lots of battery weight)! Even now he doesn't want to fit in my lab...
    Last edited by Adrenalynn; 06-02-2008 at 10:23 AM.

  2. #2
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    Re: OSCAR

    That's a very cool idea! Looking forward to watching your progress.

    Do you have plans yet for route planning, navigation and obstacle avoidance? An autonomous vehicle that large will need to be especially safe, especially one with a Sesame Street character to act as child magnet.

  3. #3
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    Re: OSCAR

    Totally agreed!

    The plans at the moment ("no battle plan ever survives contact with the enemy**") are for home-brewed 3D laser ranging and obstacle plotting at about 7" height, on all four sides, as well as a full complement of IR and ultrasound.

    Route planning via visual SLAM backed by subscription high-res GPS. The intelligence will be weighted towards "brake first, decide later".

    Even with all that, I expect it will be escorted. It has triple-redundant runaway kill switching as well. 315Mhz long-range (4000+ feet), 433Mhz medium-range (1500'), and a super-long-range over amateur radio (2m)

    We're talking about several hundred pounds capable of moving at least a thousand pounds, and able to accelerate to nearly 30mph. This isn't a toy and safety is being designed in from the ground up. We're even looking at weight-shift in case some kid jumps on the bot - we'll be able to have it automagically shut down instantly and issue an alarm.

    Processing planned right now includes 2x PicoITX, 2x duocore MiniITX, 3x Arduino, and some custom-built stuff I'll talk about later (super-dense) analog and digital input channels.

    Great questions, Meta! Please keep 'em coming! As you mention, this is a potentially hazardous project - more input is ALWAYS appreciated!


    ** Field Marshall Helmuth Carl Bernard von Moltke

    [edit: Forgot to attribute the quote...]
    Last edited by Adrenalynn; 06-02-2008 at 12:09 PM.

  4. #4
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    Re: OSCAR

    Very cool project!
    When it comes to “bots” big is beautiful!
    I gathered from previous posts that you were using golf cart motors. Do you plan on using the whole rear axle assembly? I assume not since you are “dual motoring”, or was that in order to handle the “skid-steering” that you decided against?
    As you can tell I am excited for you on this project that said, I promise I will try and keep the questions in check.
    Please keep the pictures and details coming!

  5. #5
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    Re: OSCAR

    Not at all! Thank you for your interest!

    The plan is to direct-drive each wheel via chain-drive. As it stands right now I'll bolt-up a cog on each wheel and run the chaindrive to the motors. Even though we've scrapped the slip-skid, I figure a "pseudo-slip-skid" will assist the turning servo which I'm still not confident of. Really I need to load up the cart and put a force-meter on the turning scissor and see how much torque I'm really going to require. Also experimenting with the hybrid skid I proposed above vs just straight drive.

    It's pretty young yet, so there's still a lot to flesh-out. I haven't attempted anything quite this large before, nor quite this specialized. The garden cart is beautiful, but it did create more questions than it answered, me thinks

  6. #6
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    Re: OSCAR

    Hey Adrenalynn, This project is absolutely gorgeous, i can't wait to see how this pans out. You are going to a lot of trouble here and cost to get this project going. I admire your goals here as this is a huge project. Are you doing ALL your own hardware? I know your doing software, Like me I can only do hardware and a small bit of software, If you can do both from the ground up that's great, But it is also nice to have input as I find you can get side tracked on projects with one train of thought until another person says, well how about this for an idea. Then it snowballs again. Great work.
    People yearn after this robotic dream, but you can't strip your life of all meaning, emotion and feeling and expect to function.


  7. #7
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    Re: OSCAR

    Really I need to load up the cart and put a force-meter on the turning scissor and see how much torque I'm really going to require.
    Hmmm… A couple of quick thoughts
    Have you determined (best guessed) what the all up weight will be loaded before dumping the rubbish? That will go along way toward determining how much force will be needed.
    It is easier to turn moving wheels than wheels that are static, and the footprint of the tire will greatly impact that force as well. You can affect the footprint by over inflating the tires (unless they are foam filled). That said, I would recommend doing your turn tests at 10% under inflated, for real world conditions.

    I gather you have already acquired your motors and controllers?

    This project parallels one of mine pretty closely (your dumping and I am mowing). Both are 36v, both are heavy, and both share dangers inherent with turning something big loose on the world. It will be with great interest that I follow your progress.

  8. #8
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    Re: OSCAR

    Hi 4mem,

    Thanks! I do have another person helping me, a friend of mine from way back. But yes - I do my own hardware and software. He's my hydro/pneumo expert though.

    A huge reason for posting these early to the forum is to get input from people such as yourself and Ooops! More heads are always better!

    -------
    Ooops,

    I really value your input too! You obviously have a lot of "hardware" experience - the term used as not commonly used here.

    I had a work-up but now I need to rework it with the new cart. With trash I'll be shooting for approx. 500lbs (overestimate/hyper conservative). I've simulated the forces on the new tires, but I don't have time today to simulate the turning mechanism (which is always open for redesign). Sometimes it's just easier to jam a force-meter on something and measure it than it is to simulate it, you know?

    The motors are in the vices right now and the motor controllers are connected to 'em, powered by lawn tractor batteries. They have high-current ammeters inline at the moment so I can build power/current graphs for them when I get time...

    With your mower, saying "Ooops" won't be a good thing. How comes your project?

  9. #9
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    Re: OSCAR

    With your mower, saying "Ooops" won't be a good thing. How comes your project?


    Ooops is never a good thing … except here (hopefully)
    Progress is being made. The big mower has dual 36v motor and axles mounted – but looks funny due to the size of the axles. I will be working on that.
    The little ATV mower has a main frame all welded up and is ready to have the motors/wheels mounted.
    I need to figure out how to post the pictures and then I will start a thread.

  10. #10
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    Re: OSCAR

    Eesh on the skid steering. We had a 200+ lb bot in college that was a 4 wheel drive skid steer. Anytime you commanded a turn on pavement it would jump around like you couldn't believe!

    Maybe we were just incompetent (its possible, we were in college after all :P) but I would personally be wary of skidding something that heavy.

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