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small Mecanum bot — Parallax Forums

small Mecanum bot

RaymanRayman Posts: 16,427
edited 2026-05-25 18:50 in Robotics

Started working on this thing... Think will fit with P1 to start with...

https://www.amazon.com/dp/B09P2XR91Z?th=1

Drew it up in SolidWorks to help think about motor driver PCB...

Think will use two of these dual motor drivers:
https://www.amazon.com/dp/B0F43L7LLD?
Sparkfun also sells something that looks identical, in case these ones are bad for some reason...

Comments

  • RaymanRayman Posts: 16,427

    Just ordered these long boards to drive the motors...
    The idea is that everything is controlled by one QWIIC cable from Propeller PCB.

    Uses two of these boards, one for each side. Each has a 16 I/O Expander and a dual motor driver (plus some extra stuff).

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  • pilot0315pilot0315 Posts: 1,002
    edited 2026-02-21 07:58

    @Rayman
    Howdy this is Martin.
    I have been fascinated with the mechanum wheels. Bought several sets.
    But the best place I found was Goodwill where I get r.c. cars and tear them down for parts.

  • RaymanRayman Posts: 16,427
    edited 2026-05-25 18:57

    Finally got around to working on this...

    I2C I/O Expander is working.
    Original plan was to generate the PWM for the motors using a pin in I/O Expander. But now, think this is too hard and may not work right...
    Going to use P1 I/O for PWM instead now.

    Did this form and fit test on the bot with the I/O Expander / Motor Driver boards.
    Had to drill out some of the holes a bit to get M3 standoffs in. Only using 2 screws to connect these boards to robot. Using unsecured standoffs for the other two holes...

    Just remembered that going to need some battery packs in there too, have to figure that one out still... Maybe 3D print some kind of holder...

    Wish the name was "Mechanum", but guess it's "Mecanum", bad decision... Anyway, had to change the name of this thread and some folders to match the unfortunate reality...

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  • Kool stuff. One of my next projects uses these wheels.

  • RaymanRayman Posts: 16,427

    3D printed a corral for the battery pack and got it installed. This was a pain, should have installed these things BEFORE the motors, but oh well...

    The plan was to use two of these battery packs, one for motors and other high current stuff, and one for the P1 and it's accessories.
    But, guess going to try single supply. Not exactly sure how much power this pack will put out. Could be 3A and then all would be OK.
    But, might be 900mA and things might get dicey...

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  • RaymanRayman Posts: 16,427

    Just noticed some microscopic text on the back of this supply that actually lists the current outputs of all the ports.

    Seems it can actually do 3A from its usbc cable.

    This is plenty of power for bot but still don’t know how will handle surges. Hope it works without having to add caps or other things…

  • RaymanRayman Posts: 16,427

    3d Printed a fixture for holding the P1 Platform3 PCB at the top of the robot. Seems like it will work, just need to find some more screws...

    Think the bones are all together now, just need to wire it up...

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