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Resolved Incredible servo resolution... can I get this accuracy with wiper motors? [Solved! - my error]

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Qlittles, Apr 5, 2020.

  1. Qlittles

    Qlittles Active Member

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    Hello, I have a question for my second attempt at a G-seat. In my first attempt, I had two 60kg servos pushing the back flaps for my G-seat. They were incredibly accurate even though I used only 45 degrees. For example, when I drive the Abarth 500 Assetto Corse, I can feel my back flaps vibrating from the engine vibrations (even at idle). All this time, I was missing out on detail! However, the 60kg servo eventually died, and looking at what people have posted here, it seems like these small servos will eventually die.

    My solution was to get the 100kg servos from China, but due to the Coronavirus, my orders got cancelled... and I was also thinking that these might burn out as well eventually.

    My current solution is to use wiper motors to drive the back flaps, and I've made custom hall sensor pots, with an accuracy of about 2-3 distinctions per degree (so, about 400 steps for 180 degrees). However, using these, I can't get the engine vibrations to kick in. I'm using all 180 degrees, and even exaggerated the forces using the Tuner Center (just for testing). The motor works for everything else, but NOT the engine vibrations. I'm a little confused -- are the servo resolutions that much better? In my calculations, they would have to be at least 10 times better than my hall effect sensor pots.... Is this correct? Or am I missing something?

    Is there anyone who's not using servos, and can feel the engine vibrations from the Abarth 500?

    Is the Arduino code for the servo superior to SMC3?

    Any help would be greatly appreciated :)
    Last edited: Apr 5, 2020
  2. Ads Master

    Ads Master

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  3. Qlittles

    Qlittles Active Member

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    So, I've been thinking on my experience with the servos, and now I have a suspicion that it's not the resolution, but the code that is somehow different between SM3 and the servo code. I want to try to control my motor using the servo code PWM output by using another arduino to interpret the PWM signal and control the motor (like a custom made servo). Is this possible? and what would the code look like?
  4. Gadget999

    Gadget999 Well-Known Member

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    do the wiper motors have worm drive gearboxes ? is there backlash in the gearbox ?
  5. Qlittles

    Qlittles Active Member

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    ah, i've tested it with both a worm-gear motor and a wiper motor if that makes any difference? maybe the wiper motor gears are less accurate?
  6. Qlittles

    Qlittles Active Member

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    FACEPALM!!!! So, I found the problem. I rechecked everything with the servos, and I was testing THE WRONG CAR when testing the motors. The actual car to test is Abarth 595 ss, the smallest car, and the vibrations come when the car starts moving (and not at idle). The vibrations come through to my worm-gear motor, so problem solved! (now i need to test with the wiper motor)
    • Like Like x 1
  7. Gadget999

    Gadget999 Well-Known Member

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    Is the potentiometer on the motor shaft or the worm shaft ?

    Can you set a deadzone in the controller ?
  8. Qlittles

    Qlittles Active Member

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    I have the pot on the backside of the motor arm (hall sensor), and yes, I can set a deadzone in SMC utilities (it's set to 0 atm). I DO get the detail I was talking about on the wiper motors, but not as much as the worm gear motors (same settings). Perhaps the worm gear motors are inherently better for detail?
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    I don't know the motor specs so am only guessing, but perhaps the worm gear motors have a higher rpm and overall speed.
  10. Gadget999

    Gadget999 Well-Known Member

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    are you using a shaft encoder to count rotation