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Just received 2 HB-25s and need motors/wheels suggestions — Parallax Forums

Just received 2 HB-25s and need motors/wheels suggestions

llryanllryan Posts: 5
edited 2007-02-05 14:24 in Robotics
My project is to replicate my boebot on a larger scale. Currently, on my boebot, I have the ping module and IR working like a champ and my software works well in autonomous mode. Based on this success, I want to make a bigger bot using the same programming and sensor techniques. The HB-25 seemed to be a good starting place.

My question: Which motors and wheels are recommended?· I want to use 12V only, two motors controlled independently by two HB-25s, wheels 6 in dia or more and speed close to human walking speed. I will use a free pivot wheel in the back of the bot in boebot or R2D2 style. Direct drive will be used - no chains or sprockets (that will be a future project).

My problem: Lots of suitable motors are advertised but I also need mounting brackets and wheels that would mount on whatever motor. I don't have a machine shop at my disposal. I want to purchase a pair of motors and parts·to mount·on a chassis·and attach the large 6 in wheels.·

Any suggestions would be appreciated.

Comments

  • John R.John R. Posts: 1,376
    edited 2007-02-04 21:20
    You mention "Direct Drive". This really means you want a "gear motor". Without a gear motor, I don't think you'll get anything close to the speed you're talking, unless you walk really, really fast.

    Try taking a look at this site: www.robotmarketplace.com/marketplace_motors.html. You will probably want to shop around, but at least this will give you a start on what kinds of motors are avaialable. The page I linked to is the "motors" page, but that same site also has wheels, tires and hubs to go with the motors.

    To get a feel for the speed, use this formula:
        Motor RPM * Wheel(Tire) Dia in inches * Pi  = Inches per Minute



    Once you have a few motors that get you the speed with an appropriate tire size, then you can look at voltage, torque and cost to make a choice.

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    John R.
    Link to My Nomad Build Log
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2007-02-04 23:21
    Looks like www.robotcombat.com has lots of substantial stuff (motors, wheels, chains, etc.)
  • llryanllryan Posts: 5
    edited 2007-02-05 06:02
    Thanks! I found exactly what I need. I'm going to use NPC 41250 motors (gear motor 48.5:1) running on 12V and using the HB-25 as controllers. I got 8 in wheels that bolt on easily. I notice one vendor was selling Victors along with the motors. Although I believe the Victors handle more current, I like the HB-25's compatibility with my BS2 controller and software. It looks like it will work fine on 12V. Even though the motors are expen$ive, they are big enough to power whatever future project I build.
    Using the formula supplied by John R. and using a nominal 85 RPM (12 V @ 10 A): 85 RPM * 8 in * 3.14 = 2135 in/min = 35.6 in/sec Acceptable speed.
    Am I headed in the right direction?
    Thanks for the replies.
    LR
  • John R.John R. Posts: 1,376
    edited 2007-02-05 14:24
    You're on your way! That's about one long stride per second, which sounds like a good walking pace.

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    John R.
    Click here to see my Nomad Build Log
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