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Compact Full frame, 2Dof with TL

Discussion in 'DIY Motion Simulator Projects' started by Rav3n87, Sep 23, 2020.

  1. Rav3n87

    Rav3n87 Active Member

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    Starting to think this is a motor/box/overall design choice problem which is a total bummer

    Think I might need to start looking for some 50:1s
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    There seems to be something really odd with your control board.

    Can you please verify SC3 is Mode 1 then set PWMmax and PWMmin to 60, kp to 400. Then increase PWMmax and run the square wave test and post a picture at whatever value the motor starts to move.
    • Like Like x 1
  3. Rav3n87

    Rav3n87 Active Member

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    @noorbeast

    this board is meant to be run in mode 2 from my understanding, and if I set pwmin to anything other than 0 it goes mental

    here's a video of the control board status lights



    Cheers
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Mode 2 then if that is correct for that board, but please run and post with the settings I outlined.
  5. Rav3n87

    Rav3n87 Active Member

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  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Can you please do it again, setting kp at 500, PWMmax and PWMrev to 110, with and PWMmin to 0.
  7. Blame73

    Blame73 Well-Known Member

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    wow, it really has some rebounds there!

    Hmmm, I see you're using the first hole, the closest to the axis. I think this way (because of the lever arm) any little movement makes you go away from the target and this is why it starts rebounding: it accelerates to the target, when it gets to it it has to brake but it's already far from target so it has to reverse and so on.
    Why don't you try a farther hole? I'm using one that's 9cm (from center of axis to center of hole), your motor/gearbox should handle it
  8. Rav3n87

    Rav3n87 Active Member

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    Hey @Blame73

    Yeah I was using the holes further out before and unfortunately had the same result

    Thanks for the thought though!!

    At this stage all input it great haha!!!!!
  9. Rav3n87

    Rav3n87 Active Member

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    Sorry Noorbeast i'll get to that test this afternoon and chuck up another video,

    I'm still not convinced this is wholly a motor/gearbox issue or SMC3 utils settings issue but I don't know how to read the Smc3 code and alter it for stronger centre point or if its even possible, and i can't find any other information from anyone or anywhere that has had a similar issue with or without similar components unfortunately, which leads me to the conclusion that the sheer mechanical strength of the 50:1 and higher ratio gearboxes must simply mask the issue (with my electrical components atleast)

    Had a quick look today and worst case i can go with the below if necessary

    I can get 180w motors coupled to 50:1 gearboxes from Pgsaw for $190ish aud each and postage is a bit of a killer at $289aud :(

    Now Ive been on motion dynamics website and the 50:1 boxes are out of stock unfortunately but i can get 2x 60:1 gearboxes for around the $300 mark shipped (No motors) but they are compatible with the 200w motors i already have, The traction loss I think was working quite well with the 25:1 and I'd be happy to continue with it for the moment.

    Will the 60:1's be ok or too slow?

    Or does anyone have some better options or ideas?


    Thanks @noorbeast for your help and patience over the last few days while I've bashed my head against the wall trying to work it out you have actually taught me quite alot and its helping big time!!!, and thank you everyone else for your input it is muchly appreciated!
  10. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    I suspect it may be a control board fault, but the requested tests are to try and pin that down for sure.

    I have have used 50:1 and 60:1 from Motion Dynamics and would suggest the latter, as they have beefy solid shafts (does mean changing lever design), can't be back driven when not powered on, and have been reliable for many years .

    Speed wise a 60:1 can be compensated for via lever length and design, just keep in mind the tradeoff, that the longer the lever the more pronounced backlash is, which is not really an issue for compact rigs like mine, but can be a consideration for other designs.
  11. Rav3n87

    Rav3n87 Active Member

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    Ok not a problem, If its a fault on the board I'd have to be really unlucky for all 3 to be like that :(

    Cool atleast the 60:1's will be ok then, Lever redo isn't an issue and i can have a collar with a key way made pretty easy to the solid shaft, are the gears inside of them atleast all metal? the current one's the output is nylon
  12. Rav3n87

    Rav3n87 Active Member

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    Again im not overly knowledgeable with arduino code and altering settings but is the below Found from the manufactures site relevant to the issue I'm facing and potentially any issues in the code to cause it?


    Brakes the motor when PWM pin is low (logic low) Not braking around center?

    Support both locked-antiphase and sign-magnitude for external PWM operation as below:

    Sign-magnitude mode

    You require 2 separate signals to control the motor, one is for direction (counterclockwise or clockwise) and another is for the speed. To control motor direction, DIR pin is connected to HIGH or LOW for different direction, whereas PWM pin is fed with PWM signal to control the motor speed.
    Locked anti-phase mode
    In this mode, only 1 signal is required to control both speed and direction of motor. PWM pin of MD10C is always connected to HIGH (5V), while DIR pin is fed with d to PWM signal. The direction of motor depends on whether the duty cycle of PWM signal is less than or more than 50%. The motor will run in one direction if the duty cycle is less than 50% and another direction if more than 50%. The motor stops if duty cycle is 50% (approximately). The speed depends on the percentage of duty cycle.

    I'm guessing it should be in Sign-Magnitude mode and it is wired accordingly
  13. Rav3n87

    Rav3n87 Active Member

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    Oki doki latest test video




    Cheers
  14. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Can you please temporarily disconnect the rods from the levers and run that test again, as the rig looks to be unbalanced.
  15. Rav3n87

    Rav3n87 Active Member

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  16. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  17. Rav3n87

    Rav3n87 Active Member

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    Oh yep no worries




    Thanks
  18. Rav3n87

    Rav3n87 Active Member

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    ***EDIT***
    Looked at the smc3 master code and its the same so probably disregard the below!!!
    will leave the post here for anyone else that thinks like me lol

    hmmm reading through the code again and came across this, Description of thoughts in bold)


    void SetOutputsMotor2() // MODE2
    {
    if ((Feedback2>InputClipMax2) && (PWMrev2 != 0))
    {
    PWMout2 = PWMrev2;
    OutputPort &= ~(1 << ENApin2); // Unset Motor2 In 1
    MyPWMWrite(PWMpin2, 255-PWMrev2);
    //WAS ==> MyPWMWrite(PWMpin2, PWMrev2); ------------- MOD By Blame73 for Cytron MD30C
    }
    else if ((Feedback2<InputClipMin2) && (PWMrev2 != 0))
    {
    PWMout2 = PWMrev2;
    OutputPort |= 1 << ENApin2; // Set Motor2 In 1
    MyPWMWrite(PWMpin2, 255-PWMrev2); (HERE)
    }
    else if((Target2 > (Feedback2 + DeadZone2)) || (Target2 < (Feedback2 - DeadZone2)))
    {
    if (PWMout2 >= 0)
    {
    // Drive Motor Forward
    PWMout2+=PWMoffset2;
    if(PWMout2 > PWMmax2+LiftFactor2){PWMout2=PWMmax2+LiftFactor2;}
    OutputPort |= 1 << ENApin2; // Set Motor2 In 1
    MyPWMWrite(PWMpin2, PWMout2); (AND HERE)
    //WAS ==> MyPWMWrite(PWMpin2, 255-PWMout2); // Motor driven when PWM=0 (unset) ------------- MOD By Blame73 for Cytron MD30C
    }
    else
    {
    // Drive Motor Backwards
    PWMout2 = abs(PWMout2);
    PWMout2+=PWMoffset2;
    if(PWMout2 > PWMmax2){PWMout2=PWMmax2;}
    OutputPort &= ~(1 << ENApin2); // Unset Motor2 In 1
    MyPWMWrite(PWMpin2, PWMout2); (******ALSO THIS LINE*******)
    }
    }
    else
    {
    // Brake Motor
    OutputPort &= ~(1 << ENApin2); // Unset Motor2 In 1
    PWMout2=PWMoffset2;
    MyPWMWrite(PWMpin2, 0);

    Above on drive motor backwards on the last line it says: "MyPWMWrite(PWMpin2, PWMout2)"

    But on the last line of brake it just has: MyPWMWrite(PWMpin2, 0);

    My thinking is should it write: MyPWMWrite(PWMpin2, PWMout0); to actually brake??
    Apologies again i am not an arduino coding wizard :(


    Cheers
    Last edited: Jan 10, 2023
  19. Rav3n87

    Rav3n87 Active Member

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    @Blame73

    Hey Mate, Not sure if you are still running the same controllers or not? would you be willing to post a pic of your SMC3 settings? Or even just if you have any PWMmin? I can't set any PWMmin or the motors just start rocking massively

    Have posted some more videos above with the rod detached and its still doing the same thing with no load on it :( Any thoughts?

    I think you may have not had the issue due to mechanical resistance of the 50:1 gearboxes, is there anything I could look at adjusting in the code?

    Cheers
    Last edited: Jan 11, 2023
  20. Rav3n87

    Rav3n87 Active Member

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    UPDATE....

    Issue with motor/gearboxes resolved, The 25:1's were simply not strong enough for this application/design

    Now running 60:1's up front and will purchase another for the traction loss in the next week or so,

    Motion profile set up on Iracing and feels very good, Still a bit jerky which is mainly due to backlash now which i will attempt to mask by using gas struts on the front corners,

    I also have a little twist in my uni joint it seems, not sure if a rebuild of the joint will sort it out but will try that first and if necessary I'll come up with another solution to keep it from twisting

    Lastly the front pivot bearing (caster wheel frame style) is utter garbage, It has flex side to side which only adds to the above problems to make the whole thing a bit sloppy,

    Once these issues are resolved i believe it will be quite good, Had a couple of friends over to assist with tuning yesterday and testing and if we focus on just the movements from the profile setup it feels good, but hard to ignore the backlash, twist and side to side play.

    Question time: Has anyone used gas struts? I've seen it mentioned but can't find any photos of how they mounted them,

    Is there a particular Newton rating that is recommended to use?

    I'm assuming you set them up at their half way point if possible to provide smoothing over the whole motion range?

    Cheers everyone for your time and input so far, Been a hell of a ride haha