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Question My 4dof motion simulator

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Hale L, Jun 17, 2020.

  1. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    They really shouldn't have a range issue, the motors could spin in circles without any binding because it is a triangular 3dof design. They are 24v dc motors. There is a picture of them on the first page. I didn't ground isolate them. Edit: When I start up smc3 should I have my motors in any particular position?
  2. moaale

    moaale IAN MRTIN

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    My Motion Simulator:
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    As well as the motor is turning, it seems that you are forcing the potentiometer ... I think that the motor rod should be right in the 0 position, that is, right ... the inclined rod would be at 50 and looking up at 100 and when you try any of the movements of the SMC3 the green line of the potentiometer has to follow the gray line ... it is understood ... try changing the potentiometer and if you see that the green line is moving away from the gray, reverse the motor poles so that the green line is die like the gray one .. is increasing the Max power gradually to see if the lines come together.
  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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  4. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    IMG_6405.PNG What do you mean by putting the motor rod at 0? Is that a starting position? Are you saying the crank? Ill post a picture maybe you could help me understand. And when you say change the potentiometer do you mean change the polarity? Thank you for your help
  5. moaale

    moaale IAN MRTIN

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    My Motion Simulator:
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    I say because if the motor rotated without stopping, the potentiometer could have blown you ... by the lellende of the SMC3 that the green line does not follow the gray one.
  6. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    So I was able to get all of my motors working in smc3. I need to tune them to be smother now. I was able to get my third motor two work by switching negative and positive wires. I'm only able to get motor 1 and 2 to work in simtools. Any suggestions to get my third motor moving in simtools? Here's a picture of my most recent simtools settings. Thank you to everyone who's helping, Nice to see some progress being made again. Felt like I was at a standstill for a couple days lol. 1.PNG
  7. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    If I recall you were using 2 Arduino's, is that correct?

    If so you will need to use the Interface2 tab and configure it for the 2nd Arduino, including the correct com port.
  8. Hale L

    Hale L Sim Racer

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    I switched to 1 Arduino for now until I add traction loss just to keep it simple.
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    In that case you have an incorrect bracket in your Interface Settings, it should be: [A<Axis1a>][B<Axis2a>][C<Axis3a>]
  10. Hale L

    Hale L Sim Racer

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    Ok thank you that worked just a typo. How can I change the default starting positions of my motors? because the second motor starts lower than the rest? Can I do it with the programming? Or do I have to do It manually with a battery?
  11. moaale

    moaale IAN MRTIN

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    My Motion Simulator:
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    In my 2dof simulator, to accommodate the 2 pots, I decouple the potentiometers or the potentiometer of each motor, I turn on the 12v source and with the potentiometer I move it to position 0 until it looks like the other pots and then I turn the potentiometer to the means where it does not move anywhere I turn off the source and there I reconnect the potentiometer with the motor and it is perfect ... try like this ...
    • Agree Agree x 1
  12. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    I've been having a lot of problems with smc3 tonight. No matter what I do my motors want to start at different points, also smc3 keeps crashing on me. Also how can I have smc3 allow the motors to turn 180 degrees? I'm not able to get my motors to do that. Basically I need my motors to go from pointing at the ground to pointing straight up. Another thing is my potentiometers are 360 degrees so I wouldn't know how to set them at 0. I've been doing my best to not get frustrated tonight lol. Edit: I tried deleting arduino and smc3 to get a fresh start with all of my motors at 90 degrees so they are parallel with the floor and somehow it remembers my old settings
  13. moaale

    moaale IAN MRTIN

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    I think your problem is the potentiometers to which I all use all linear 10K potentiometers ... That's why your potentiometers rotate from a tip to the other you can get to find the center of the potentiometer so that it does not turn anywhere and couple with the engine but wing time to start a race when the potentiometer has to make a tour is very acted and long as the potentiometer has to stay standing always remain in a different position than the others .... Tell us all use 105 line potentiometers. Please change them by 10k linear and then comments me.
  14. Hale L

    Hale L Sim Racer

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    C995ED31-FC6F-42F9-A9C6-1B023AF78B22.jpeg
    These are the potentiometers that I have. They have no mechanical stop. I’ll take take a closer look at them later, but I’m Not really sure there is any way to indicate center?
  15. moaale

    moaale IAN MRTIN

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    You would have to look at the SMC3, you turn it with your hand until the green line is in the center ... and I think it will get complicated with that multiturn potentiometer
  16. yellofella

    yellofella Member

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    Hi guys
    @Hale L great work on your build so far. I have been keeping track of your build and its coming along nicely but it seems your having some problems setting up your motors so i thought id try to help. Other members have already posted some of the info and you may already know some of it but this may explain it in more detail.
    You mentioned that you require 180 degrees of movement on your motor arms. I would reduce this to 150 degrees. The potentiometers that you posted you are using are single turn but use 320 degrees of sensor travel. If you geared the pots 2:1 you would have 160 degrees of motor arm angle for a full turn of the pot. To be honest anything above 120 degrees becomes really inefficient and will reduce linear speed of your rig.
    Now in the SMC3 you need to set the max limits to about 25. This is the point that the SMC3 will disable the motors if they go into that zone. The arduino will read the voltage of the pot and convert 0-5v to a value between 0-1023. So if max limits is set to 25 then the motor will disable and turn off the power if the sensor reads between o-25 or 998- 1023. This is a great feature of the SMC3 software and is used to stop mechanical damage. With the max limits set to 25 you will loose 50 points of resolution of the 1024 available ( 8 degrees) so final motor angle would be 152 degrees without using any clipping. I would use some clipping though as in this zone the motor will drive hard in reverse to stay out of the clip zone. This will help as gravity helps to move the motor in one direction so can overshoot the position. No clipping means it will drive into max limits zone and shut the motor down Clipping will reduce the final motor angle further so you would need to adjust the pot gearing to compensate.
    To set the motor up in the SMC3 software you need to disconnect the gears that drive the pot. Move the motor manually or connect it directly to the power supply to move the motor arm to the required centre position. In your case parallel with the floor. Open the SMC3 software and move the pot buy hand until the green line is in the middle point of the graph. This is your pot centre point. Now connect the pot gears together making sure the motor arm centre point and the pot centre point stay aligned. Connect any motor wires back to the driver if removed to align motor arm.
    In the SMC3 software use these setting to start with
    Kp 400
    Ki 0
    Kd 0
    Ks 1
    fpwm to 20 khz
    max limits 23
    clip input 40
    pwm rev 0
    pwm min 0
    deadzone 0
    Select manual in the output mode and move the slider away from the mid point. Now start to raise pwm max until the motor stars to move slowly then check that the green line moves towards the blue line (blue line is the one you control with the slider). If it moves away from the blue line then reverse the motor wires. Once you have the green line following the blue line when you move the slider then you have closed loop control and can set pwm max to a much higher amount. Do the same for the other two motors before you move on to sim tools.
    I would recommend that you use shielded cable to connect your pots to the arduino. An unused usb cable works well. Cut the usb connectors of the cable and connect the shield at the arduino end only to ground. This will help to stop motor jitter when the motors are holding position and should avoid you using the deadzone. Also try to separate motor and pot wires as best you can.
    What is the tooth count on your pot gears, From the pictures it looks like they are geared higher than 2:1 so you will get less motor arm angle than you require.
    Hope this helps buddy
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  17. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    Thank you for all of your help, so far its working out, ill keep you updated. One question I have is when you say bring pwmmax to a much higher amount after you have a closed loop. How much higher?
  18. moaale

    moaale IAN MRTIN

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    I think it means to you that when you see that the 2 lines of the SMC3 GREEN AND BLUE are coupled, the potentiometer is just fitted with the motorcycle ... and the power max of the SMC3 is little by little
  19. yellofella

    yellofella Member

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    I intentionally used the phrase much higher as in giving you a set value might be dangerous. You will have to find this out for yourself but i can give you a frame of reference to work in if it helps. On my rig the PWMmax is set to 255 (as high as it will go). I know that all my cables/drivers and supplies can handle it being that high with my weight on the seat as well as pushing the brake pedal to 100% then activating surge movement forwards. I also know that the hardware that the rig is made of and all the welding can handle the forces that i am generating. I know this due to hours if not days of testing on my rig which involved slowly increasing PWMmax and KP values while checking temperatures and hardware after a set run. If i had given you a set value you may have fried a cable/destroyed a power supply/ blown a driver or maybe bend something/ break a weld or bolt. Or not had enough power to move the motors once you are on the seat.
    I don't want to be responsible for you getting hurt or costing you money or time on damages that i may have suggested that you do. I will only advise you to try things that i feel will be safe from the info and the pictures that you post. Some members just ask questions without any background info and expect us that know to answer. What they have not considered is it may be dangerous if not irresponsible to just throw a simple answer out there without some background info. So basically they ask a question and we that know ask questions back instead of answering which must seem frustrating to new comers but is the safest way. You have made a really good build log so far with lots of info that allows us all to help you safely but only if you do the testing for us. The more info you give the better we can help which will lead to a better rig for you.
    So back to your sim then. The motors will be lifting your weight constantly so will require lots of current to hold position and move at high speed. This is going to work your drivers hard and special attention should be paid to the temps that they run at and the cooling they are going to need. I have constant temp monitoring of all 3 drivers on my rig displayed on a lcd on my button box.
    I would recommend 10awg cable with good connections due to the constant current you will be supplying. I use 10awg oxygen free voodoo cable with a high strand count on my rig with soldered and heat shrunk yellow crimp connectors.
    Once you have closed loop control you feel the rig can handle the stress and the electronics can hold the current then raise the PWMmax up slowly and test. The KP value will control how fast your sim tries to get to the target position, the higher the value the faster the speed. I run KP at 550 on my rig which results in sharp fast movements. If KP is to high your motors will overshoot the target and you may have to use some KD to compensate or reduce KP. You can do as much research as you like on PID control but its like black magic so good luck.
    Hope this helps buddy and keep the info coming..
    • Like Like x 2
  20. Hale L

    Hale L Sim Racer

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    Ok thank you. I was able to get it running in dirt rally 2.0 and live for speed without heave. I think my motors are to weak with the current length of my cranks. I will be shortening them, but for now I will just use pitch and roll. I have an oculus rift s and I need to get motion compensation software, Not sure where to find it and how to install it?