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Thread: Question over mixed ax12 ax18 use

  1. #1

    Question over mixed ax12 ax18 use

    I have the PhantomX platform with AX-12s. It going to start getting a high load with additions of a up running high level ROS, Lidar, Various sensors, directional mic array A head / grabber with two AX12s and 2 hobby servos plus lights camera and printed parts hanging out front and finally 4 AW-12W running a roller system to enable a form of wheeled motion for tight spaces.

    With all this said budget remains a very big issue and i have the ability to only upgrade one 6 pack of ax-18s. My question is what would be some recommendations for placement of the ax-18s. My first thoughts where to replace all the Femurs to help with total weight load but I am concerned about the extra weight hanging out of the front. Recommendations on best loading the Hex would be very appreciated

    Thanks

    2BFoo

  2. #2

    Re: Question over mixed ax12 ax18 use

    The AX-18 are a lot faster than the AX-12, but they are not a LOT higher load capable. A little, but not a lot.
    If you actually need to bear load, I'd suggest putting torsion springs around the knees, and hip joints. As long as they help the robot "stand" against gravity when un-powered, they help a lot with overload and power consumption.
    I have some pictures for what this can look like (mounted on a Phantom X quad): https://photos.app.goo.gl/kE3zN8sbUrf9uw882
    You'd need to make some custom fasteners for the springs -- 3D printing, or CNC aluminum (I used the latter.)
    The springs themselves are something like these: https://www.mcmaster.com/#9271k621/=1bi631k
    Last edited by jwatte; 1 Week Ago at 01:09 AM.

  3. #3

    Re: Question over mixed ax12 ax18 use

    Thanks for that, Speed is not on my want list so this seems a much better route, Reducing load and resulting heat will help with stability all round and I could play with spring loading to counter the leverage of the weight out front. I also know I will need to tackle power consumption down the line so the wins going down this route just keep piling up. Again, super appreciate the direction. Thx

  4. #4

    Re: Question over mixed ax12 ax18 use

    Btw: I don't know if the spring I pointed at is the right tension for what you end up using. There are a whole slew available:
    https://www.mcmaster.com/#torsion-springs/=1bl2djf
    (There are also left-hand and right-hand versions -- useful for mirrored sides of the bot)
    Maybe these are the ones I actually used? https://www.mcmaster.com/#9271k272/=1bl2e22

  5. #5

    Re: Question over mixed ax12 ax18 use

    Quote Originally Posted by jwatte View Post
    The AX-18 are a lot faster than the AX-12, but they are not a LOT higher load capable. A little, but not a lot.
    If you actually need to bear load, I'd suggest putting torsion springs around the knees, and hip joints. As long as they help the robot "stand" against gravity when un-powered, they help a lot with overload and power consumption.
    I have some pictures for what this can look like (mounted on a Phantom X quad): https://photos.app.goo.gl/kE3zN8sbUrf9uw882
    You'd need to make some custom fasteners for the springs -- 3D printing, or CNC aluminum (I used the latter.)
    The springs themselves are something like these: https://www.mcmaster.com/#9271k621/=1bi631k
    That's a very elegant solution to counteracting torques. I've seen something similar with leaf springs, but your idea seems easier to implement. I might have to try it myself as well!

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