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Question SMC3 + Sabertooth 2x32 + ZYT90-155-12 MCP4

Discussion in 'SimTools DIY Version' started by MichaelS, Nov 28, 2019.

  1. MichaelS

    MichaelS New Member Gold Contributor

    Joined:
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    My Motion Simulator:
    2DOF, DC motor, JRK
    Hi all,

    after using the pololu jrk12v12's first and finding out that they weren't strong enough for my motors i bought a sabertooth and set it all up.

    I now face the problem that i can't get the axes from the motor to hold a position. Ive been reading a lot of posts about pid tuning and also using some setups from others in smc3 utility to try and figure out why it keeps happening.

    I have added 2 clamp resistors to the sabertooth as suggested so i don't think that will be the problem.

    I used the setup from blazinh and i believe i did that correctly as they held position after initial setup. After that i downloaded lfs on my laptop and i had some motion with simtools connected with the basic settings.

    If i up the pwMax it keeps on jittering like seen in the first two attached picture. with lower settings it is allright.

    The engines are not put under any load/weight from the rig , it is just a rod throught the motor at the moment but i do think the engines should be set dead still even without any load?

    Hope someone can point me in the right direction.

    thanks in advance!
  2. Ads Master

    Ads Master

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  3. SeatTime

    SeatTime Well-Known Member

    Joined:
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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    Try my settings below and maybe up the dead zone to see if that helps, but likely due to play in the pot/motor interface - pot needs to track any movement of the motor perfectly - no slack . Also use shielded cable between the Ard and Pot with the shielded cable signal earthed at the Ard end only. This is what one of mine looks like with everything powered up ready to go.

    smc3 running.jpg
    • Informative Informative x 1
  4. MichaelS

    MichaelS New Member Gold Contributor

    Joined:
    Oct 22, 2019
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    My Motion Simulator:
    2DOF, DC motor, JRK
    Hi @SeatTime , I will try your settings tomorrow.

    I have used Dupont jumper wires 20cm long.

    Am I right in saying the engines should hold position even when they are not putting under load from the frame so just engine and pot connected?

    Kind regards,
    Michael
  5. SeatTime

    SeatTime Well-Known Member

    Joined:
    Dec 27, 2013
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    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    Replace the jumper wires with some shielded cable, and yes the engines should hold position as directed by the data - always.