1. Hundreds of coffees, endless nights of debugging and coding, and countless feedback by our beta testers led to this new major release. SimTools 2.4 is probably the version with the most upgrades and improvements in a single release ever. Look at everything Dustin has included:
    SimTools 2.4 all features.
    Dismiss Notice
  2. For downloading SimTools plugins you need a Download Package. Get it with virtual coins that you receive for forum activity or Buy Download Package - We have a zero Spam tolerance so read our forum rules first.

    Buy Download Package Now!
  3. Do not try to cheat our system and do not post an unnecessary amount of useless posts only to earn credits here. We have a zero spam tolerance policy and this will cause a ban of your user account. Otherwise we wish you a pleasant stay here! Read the forum rules
  4. We have a few rules which you need to read and accept before posting anything here! Following these rules will keep the forum clean and your stay pleasant here. Do not following these rules will lead to permanent exclusion from this website: Read the forum rules.

_Gus's 6DOF Project

Discussion in 'DIY Motion Simulator Projects' started by _Gus, Jul 19, 2019.

Tags:
  1. SilentChill

    SilentChill Problem Maker

    Joined:
    Jul 19, 2014
    Messages:
    2,469
    Occupation:
    Railway Maintenance
    Location:
    Morecambe, Lancashire, England
    Balance:
    18,619Coins
    Ratings:
    +3,140 / 31 / -0
    My Motion Simulator:
    DC motor, Arduino, Motion platform, 6DOF

    Nice work matey !

    Think you need to turn your levers 180 degrees they are in the wrong position, too upright
  2. SilentChill

    SilentChill Problem Maker

    Joined:
    Jul 19, 2014
    Messages:
    2,469
    Occupation:
    Railway Maintenance
    Location:
    Morecambe, Lancashire, England
    Balance:
    18,619Coins
    Ratings:
    +3,140 / 31 / -0
    My Motion Simulator:
    DC motor, Arduino, Motion platform, 6DOF
    Also did you use M12 threaded bar for your rods ? They look thin
  3. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Thanks for the suggestion! I turned them around and it is far more rigid than it was before (it was wobbling all over the place before). Here's the corrected setup:

    IMG_5763.jpg

    Yeah, they are pretty thin, and I'm working on fixing this. My plan right now is to slide some steel pipe over the rods to give them some extra material, and hopefully stop them from bending. If you push on them hard enough you can notice some deviation, even without any real load on there right now.

    Here's the link to where I bought the rods: https://www.mcmaster.com/6516k18

    Aside from the construction of the rig though, I'm having the same problem with SimTools again, and it's really putting a damper on any testing progress that I might be able to make. The issue is that when I reboot my computer, startup SimTools, and go to the output testing tab, everything seems to work for about a minute or two, but then SimTools seems to lose its connection to a motor pair (single Arduino) or even two pairs. I'm just not sure how to fix this, and restarting my computer every time this comes up doesn't seem like a good fix.

    Please if anyone has encountered this problem, or has any suggestions for me at all, let me know.
  4. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
    Jul 13, 2014
    Messages:
    13,158
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    100,093Coins
    Ratings:
    +8,339 / 42 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    That could be interference, like a faulty usb cable or needing better cable management and ferrite clips on cables.

    It could also be a computer band width issue.
  5. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    I don't think it's an issue with the cables. I have five in all and so far every single one of them has demonstrated this failure, and the odds of having 5 faulty cables are incredibly low.

    Could you elaborate more on this?
  6. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
    Jul 13, 2014
    Messages:
    13,158
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    100,093Coins
    Ratings:
    +8,339 / 42 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    While there are often many on-board motherboard USB ports on a computer they normally share controllers, so if you have too much demand on a given controller it will create a band width issue.
  7. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Lets say I have 3 pairs of motors: pairs a, b, and c. Currently motor pair a is the one prone to failure, and won't run for long if the other pairs on plugged in. However, the other two pairs can run simultaneously, and so therefore would not, in this world, be on the same controller. This means that by testing a and b, or a and c, one of them should work since one must have two separate controllers.

    Unfortunately, I tried this, and it is not this case, which means it is extremely unlikely it's a bandwidth issue. Thanks for the suggestion though, it seemed totally reasonable that that could have been the issue!
  8. SilentChill

    SilentChill Problem Maker

    Joined:
    Jul 19, 2014
    Messages:
    2,469
    Occupation:
    Railway Maintenance
    Location:
    Morecambe, Lancashire, England
    Balance:
    18,619Coins
    Ratings:
    +3,140 / 31 / -0
    My Motion Simulator:
    DC motor, Arduino, Motion platform, 6DOF
    How have you got the Ards connected ? If you havent I would suggest a powered USB 2.0 hub

    5/16ths is way to thin you would need at least 1/2 inch which would be similar to the M12 size,
  9. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    I have three six foot USB A/B cables which I have been plugging directly into my computer, since I have a bunch of free usb slots. The setup is identical between the three Arduinos., and 2/3 of them always work, even when I. swap the cables and or ports. This leads me to believe its the Arduino itself, and so I'm going to try and swap the Arduinos of the faulty pair with a working pair, and see if the problem moves with it. Hopefully it does, and I can just buy another Arduino and be done with the problem.

    Yes, I realize this now. Instead of buying thicker rods and having to buy new joints, and re-mill all of the plates the joints connect to, my plan is just to slide a steel pipe with a 3/8" ID and a 3/4" OD over the rods, which should give it plenty of strength.
    • Like Like x 1
  10. SeatTime

    SeatTime Well-Known Member

    Joined:
    Dec 27, 2013
    Messages:
    2,186
    Location:
    Newcastle Australia
    Balance:
    26,019Coins
    Ratings:
    +2,473 / 23 / -0
    My Motion Simulator:
    DC motor, Motion platform, 6DOF
    You could try dropping the connection speed from 500000 to 115200. Either by earthing digital pin 8 on the Ard, or by changing the sketch (SMC3?). Some clone Ards can struggle at the 500000 speed.
  11. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Thanks for the suggestion, SeatTime. I grounded pin 8, and set the baud rate to 115200 via SimTools, however that same motor pair still failed. I also tried increasing the output rate from 10ms to 50ms to see if that would make a difference, however it did not. This leads me to believe its not a bandwidth issue.

    I also went along and tried swapping an Arduino from one of the working motor pairs with the faulty pair, however the same issue occurred with the same motor pair, meaning it is very unlikely to be an Arduino problem. Also, because I just went and rewired it, I know its not an Arduino wiring issue. I'm honestly at a loss right now...

    ---

    Looking at the system as a whole, this is the setup:

    Power supply -->
    SimTools --> USB cables --> Arduino running SMC3 --> pin 13 wire --> Sabertooth 2x32 controller --> motors

    From the tests I've conducted so far, I believe I can safely rule out the problem being related to SimTools, the USB cables, the Arduino, and the Arduino wiring.

    This leaves the following components:
    • Power supply
    • Sabertooth 2x32
    • Motors
    I don't think it could possibly be the motors, as they have no computer or ability to change their function, and they consistently work with SMC3 Utils. This means that I think it has to be either the power supply, or the sabertooth controller. I'm not sure what tests to run to narrow it down between the two components, other than simply swapping the parts around, so I guess that's my next step...

    EDIT: in my psuedo-diagram, the psu is supposed to be connected to the sabertooth
  12. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Quick update... I swapped the faulty sabertooth with a functional one, and it made no difference, ruling out the sabertooth as the problem component. I also don't think its the psu's, as they never cease to function when I'm running SMC3 Utils. I honestly don't know what to even try next.

    EDIT: I take it back. I cannot get SMC3 Utils to function with the faulty pair now. It still works with the other 2 pairs though... I'm going to try swapping the psus either tonight or tomorrow.
    Last edited: Aug 8, 2019
  13. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    I've now beefed up the connecting rods a huge amount, and beyond just knowing that they're not going to break, I also think that they look awesome. The original rods turned out to be a little less than 5/16ths, and so I had to add some plastic tubing to stop any potential rattling, so now it fits like a glove. The reinforcing pipe is low carbon steel, and has an ID of 3/8ths, and an OD of 3/4ths, so it is quite strong.

    Here's some pics:
    IMG_5780.jpeg IMG_5783.jpg
    IMG_5786.jpg
    • Like Like x 2
  14. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Another update, this time about the SimTools problem:

    When I swapped the arduinos it turns out I incorrectly did the pin13-a1 connection on the sabertooth, so it was pin13-a2 instead. I fixed this, and it appears to work now. Then, the arduino which was originally in the faulty pair was having issues connecting to SMC3 Utils as well as redownloading the code, which I tried to do to fix the connection issue. I had backordered a new arduino because I thought that might be the issue, so I swapped those out, and now all is good with the arduinos.

    Now my problem is that I have boosted the max pwm on the motors from 100 to 235 via the smc3 util, because the motors were not able to lift me up at 100. Now when I try to lift myself, or when I move the SimTools axis quickly, the Sabertooths freak out. They seem to turn off, along with the motors, and then periodically turn back on one at a time and move the motor a tiny bit, then turn off again. When they do this, the green and the red lights are on on the board. I think this is all happening because I have the whole thing plugged into the wall on the same circuit as my computer, and a minifridge, and so when the motors attempt to draw their full 1200 watts, they can't, or atleast the psus can't supply that much, which is causing the sabertooth error.

    If anyone else has experience this issue let me know, but tomorrow I'm going to try running in an extension cord to the garage to get this all on a different circuit, and see if that works. The important part though is that I'm past the simtools errors!

    Sorry if this reply is riddled with mistakes---It's almost midnight and I had a really long day today.
  15. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
    Jul 13, 2014
    Messages:
    13,158
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    100,093Coins
    Ratings:
    +8,339 / 42 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    If the motors are struggling to provide the required torque you could also try a smaller CTC on the levers.
  16. anatachaikiet

    anatachaikiet New Member

    Joined:
    Jun 28, 2019
    Messages:
    13
    Balance:
    71Coins
    Ratings:
    +0 / 0 / -0
    My Motion Simulator:
    Arduino

    thank you
  17. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Unfortunately, using a different circuit didn't fix the problem. I'm going to try using a different power strip though, because I know the one I'm using has surge protection, and may be causing the issue...

    EDIT: Nope, didn't fix it. I'm thinking that this isn't just a torque issue though, because the math says I should have plenty of torque, and if I don't have enough, the motors should just run slower.

    I also don't think its a torque issue because an identical failure also occurs when I move the motors too quickly (w/o weight), where the motors all turn off, and sort of push up a tiny bit one at a time. When this happens, the error and status LEDs flash on the sabertooth, which according to the dimension engineering site:

    "Sabertooth 2x32: If voltage is too low, Status and Error will flash. If voltage is too high, Status and Error will glow."

    so I'm thinking I have a voltage issue... but I don't quite understand what it could be, as my PSUs output 24v and can handle 480 watts, and my motors are 24v 200 watt motors. Suggestions or advice would be appreciated.

    For right now I'm going to put the PWM back down to 100 to setup the axes without issues.
    Last edited: Aug 10, 2019
  18. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    While I've not yet figured out how to get it to move me, I have configured all of the axes, and it is officially alive! Here's the motion test video:

  19. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

    Joined:
    Jul 13, 2014
    Messages:
    13,158
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    100,093Coins
    Ratings:
    +8,339 / 42 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Great to see your rig moving :thumbs

    I am repeating myself but I do think your lever CTC is too large for the intended mass and likely your levers are also at an inefficient angle.

    Levers provide maximum torque at 90 degrees to the rods, and over 38 odd degrees either side of that are pretty inefficient with respect to torque.
    Last edited: Aug 10, 2019
  20. _Gus

    _Gus Member Gold Contributor

    Joined:
    May 16, 2019
    Messages:
    41
    Balance:
    339Coins
    Ratings:
    +23 / 0 / -0
    Apologies for ignoring your last reply. I misintepereted the motors specs as having variable max torque given the max rpm of the motors, but in reality the manufacturer was describing the spec for different gearbox options. This means I have much less torque then I thought, and my motors will be putting out about 25.4 Nm of torque (I'm rounding to 25), or enough to lift only 264.5 pounds total, including the upper portion of the frame, given my CTC length. I redid the math with the correct specs, and leaving ample padding, I think my levers should be about 3.3", or about 3 and 5/16". This is a big step down from my current 5" arms, but I guess I'll have to make due. I'll try and. redrill the lever arms to incorporate a 3 5/16 length between the shaft and joint.

    Also, thank you for the advice about the arm angle. I'll try and figure out how to fix this. Right now the arms cannot fully turn down to a 90 deg. angle, without hitting the frame, and before they even get down close, the rod will hit the lever arm.

    Lots of things to think about!

    Just out of curiosity, how long are your guys's lever arms?