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Thread: Mini Sumo

  1. #1
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    Mini Sumo

    Hello evryone!

    So I wanted to open this thread for mini sumos. I want to build my own soon and I'm looking at a lot of motors, motor controllers, microntroller.

    I wanted to have some info on the maxon motors a lot of people seem to be using. What are the RPMs With a load? 16500 without load seems still pretty fast. I also wanted to know how much current the motors use under stall?

    I have my own ideas for the other things. I will talk about it latter on

    Sam

  2. Re: Mini Sumo

    Sam,

    The Maxon motors I am using have a 17:1 gearbox on them, so their rated RPM is 970. In reality on a mini-sumo they aren't going to spin that fast, probably more like 600-700 RPM due to the load.

    Note that even at 600 RPM, with 1" diameter tires (like I'm using), you're looking at 31 inches per second at full speed. A mini-sumo ring is 27" in diameter, so you're going to need to be very precise and very fast about responses. At 31" per second, in 1/10 second you're going to cover 3".

    The stall current is rated at just over 1.2 amps. I'm using a couple of this motor controller, although I might have used this one if it would have existed when I designed Seeker 2x.

    Attachment 578
    "The best way to predict the future is to invent it." - Alan Kay, inventor of Smalltalk

  3. #3
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    Re: Mini Sumo

    Ok, I thought that 16500 was WITH the gearbox, I was getting worried .

    I was looking at this motor controller.

    http://www.pololu.com/catalog/product/411/faqs

    It's small so I could connect it to the main board and it wouldn't take up too much space. The only downside is that it's rated 1 Amp max each motor. But I could put two controller boards to control two maxon motors.

  4. Re: Mini Sumo

    The PWM frequency for that controller isn't great - 600-750 Hz.

    The one I am using is basically the same price, but handles 5 amps (2.5 amps continuous), can do 10 kHz PWM, and has an analog line that gives feedback on motor current consumption.

    I guess it really depends on what you're using as a micro-controller. If you're using something like a Basic Stamp, which doesn't do motor PWM, then the serial model would be better.
    "The best way to predict the future is to invent it." - Alan Kay, inventor of Smalltalk

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    Re: Mini Sumo

    Waht does the PWM frenquency does in a normal motor controller? It gives you better control over your motors?

    The Basic Stamp can do PWM. Is that different than motor PWM?

    Thanks for the information

  6. Re: Mini Sumo

    The Basic Stamp can do a very limited form of PWM. Basically, while its doing PWM on one pin, it can't do anything else. On a real micro-controller, you can set up the hardware PWM to do it, so it happens completely in the background, without consuming any CPU.
    "The best way to predict the future is to invent it." - Alan Kay, inventor of Smalltalk

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    Re: Mini Sumo

    Humm, Well I have a Atmega 168 lying around, maybe I could use it for the mini-sumo. Would it be better with PWM?

    The only trouble is that I don't with what language I can program it and how to connect it to my computer... Serial port?

  8. Re: Mini Sumo

    I use ATmega168's all the time. In fact, I'm putting one in my handheld remote kill switch. The 168 can do PWM in hardware no problem, and it has a lot of other nice features that make it ideal for small robots.

    You can program it in C or Basic. I use gcc to program my ATmegas. You can definitely connect it to your computer using serial. I use a USB-TTL converter to allow me to get the AVR's serial port output on a serial console like HyperTerminal.

    I use this programmer for all my AVRs. Simple, USB, and it works great.
    "The best way to predict the future is to invent it." - Alan Kay, inventor of Smalltalk

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    Re: Mini Sumo

    In answer to your other question: A wider range gives you finer granularity of speed control.
    I Void Warranties´┐Ż

  10. Re: Mini Sumo

    Where might one purchase the Atmel 168 Programmable Integrated Circuit unit, What are the dimensional requirements for a regulation Miniature Sumo Automaton and what is the ideal conveyance units (electrical, electronic and Direct electrical Current motor). I have taken considerations in constructing a Miniature Sumo automaton chasis, but I have not considered the layers of conveyance to utilize in my construct, hence the questions I have posted to this, the Trossen Robotics Community thread. I am in need of assistance, as my queries may imply.
    "Are going to eat that?"

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