1. 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!
  2. 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
  3. 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.

Heavy Duty 2DOF

Discussion in 'DIY Motion Simulator Projects' started by GTexas, Jul 4, 2017.

  1. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    Hi y'all.
    First thought was to build a 3DOF flight-sim, but then decided to get some practice with a 2DOF seat mover first. Starting point was a leather car seat from a 2011 Mustang GT and a Fanatec wheel, then added H-Shifter and inverted pedals. Planning on +/- 15 degrees of roll and pitch, so considering the weight to be moved I opted for heavy duty wheel chair motors (24 VDC). I could not get data on the motors so far, but they look very solid and are in working condition. Plan is to use an Arduino Uno and Sabertooth 2x32.

    Here some pictures of the mechanical setup (still static).
    HD2DOF001.jpg

    HD2DOF006.jpg
  2. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    As also my kids will be driving the sim, the whole rig needed to be fully adjustable. The seat position is fixed (pitch and roll movements via a U-Joint from a motorcycle, pics will follow), the whole table with the wheel and shifter can slide on the base plate between the wooden rails.

    HD2DOF002.jpg

    It can be fixed in position with the knob bolt and T-nuts in the base plate at different positions:
    HD2DOF003.jpg

    HD2DOF004.jpg

    HD2DOF015.jpg

    HD2DOF016.jpg

    Once the arm-length distance from the seat to the wheel and shifter is adjusted, the pedals can be adjusted separately. I used the seat rails which came with the seat. Make sue to get a mechanical seat, not an electric. Also get a passenger seat. They are typically less worn out and cheaper.

    HD2DOF005.jpg

    HD2DOF009.jpg

    So far for the static set-up, now to the moving parts.

    Here is a pic of the motors, I hope they will not have too much inertia. When running on no load they took a while to stop.

    HD2DOF010.jpg

    For the power supply I got two used server power supplies HP DPS-1200FB A. They produce 12V and 75 Amps each when run at 110V supply. To get 24 V they obviously have to be connected in series. As the 12V GND is connected to the casing and AC ground one of the supplies has to be floated. Some float these power supplies by disconnecting the mains ground which I would strongly recommend against as the ground protection for the metal case would be gone.

    HD2DOF011.jpg

    To float one of the supplies open the casing and remove the PCB. It sits on 3 metal posts and is mounted with M3 bolts to the casing posts. All you need to do is to carefully enlarge the mounting holes in the PCB to 4 mm (do not go larger in order to not destroy any layers), shorten the metal mounting posts with a Dremel by the height of the insulator you are going to put in) and remount with nylon insulators typically used to mount large power transistors:

    HD2DOF014.jpg

    First picture shows the non-floating unit (with the original mounts):

    HD2DOF013m.jpg

    The pic also shows the 1 kOhm resistor needed between Pin 33 and 36 to trick the power supply into thinking it is in a server rack and to power up.

    The second pic shows the modified mount with the shortened supports and nylon insulators above and below the PCB:

    HD2DOF012m.jpg

    As mentioned before this way of floating the power supply is preferred as the grounding of the metal casing remains intact.

    To link the motors to the seat I am currently planning on levers with 50 mm CTC to obtain the +/- 15 degrees for roll and pitch.
    Last edited: Jul 4, 2017
  3. MarkusB

    MarkusB Active Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    334
    Location:
    Germany
    Balance:
    2,403Coins
    Ratings:
    +281 / 1 / -0
    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    Hi @GTexas,
    your static rig looks nice.
    I have just one comment about the highlighted parts of your statement above: According to my own experience, +/- 15 degrees are far too much for a seat mover.
    The first version of my rig was also a seat mover, and it only had about +/- 7 degrees of roll and pitch. And even with this smaller angle it felt very unnatural for me to have my body except my feet tilting. For example, when the rig did a pitch movement I felt my knee joints bend, and this did essentially reduce the feeling of immersion.
    This was the reason for me to mount the pedals to the seat, so that now my entire body is moving.

    Best regards,
    Markus
    • Agree Agree x 1
  4. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    Hi Markus,
    Good point. The planning was still influenced by the flightsim I wanted to build originally. I have not cut and drilled the levers yet, so I will follow your recommendation and reduce the CTC. The setup I currently have would not allow to mount the pedals to the seat.
    Maybe in the next project when switching to a 3DOF.
  5. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator SimTools 2.0 Beta Tester

    Joined:
    Jul 13, 2014
    Messages:
    12,022
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    93,213Coins
    Ratings:
    +7,810 / 37 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    It has been a while, how is your project progressing?
  6. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    Hi noorbeast. Thanks for checking in. We had a little hicc-up here in Houston with hurricane Harvey, so the simulator project has not been in focus recently. Now also our outdoor season started.
    Only progress made so far was replacing the 3 monitor set-up with a HTC Vive, which is awesome.
    Still need to connect the motors to the rig. I have all the bits and pieces here including Arduino, I am just lacking time right now.
  7. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator SimTools 2.0 Beta Tester

    Joined:
    Jul 13, 2014
    Messages:
    12,022
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    93,213Coins
    Ratings:
    +7,810 / 37 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Life happens, hang in there and we will look forward to future updates when the rest of your world settles down.
    • Friendly Friendly x 1
  8. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator SimTools 2.0 Beta Tester

    Joined:
    Jul 13, 2014
    Messages:
    12,022
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    93,213Coins
    Ratings:
    +7,810 / 37 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Has life settled down and have you you managed to get your rig hooked up yet?
  9. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    OK, I am finally back in business. Here are the pics of the motorcycle U-Joint mounted to the seat base plate and the U-Joint base. For the base I used a conduit tee which has the advantage that the seat can be easily dismantled at a later stage.
    • Like Like x 1
  10. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
  11. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    @MarkusB : After looking at my motors I noticed they have a shaft diameter of 3/4" , the keyed coupling has an OD of 37 mm. Considering the bolt & nut diameter of the rod end I do not believe that I can go with less CTC than 28 mm. With the geometry I have this will result in about 7.5 degrees roll and pitch with 38 mm travel. Will be rough for a seat mover with static pedals, but I do not want to change the whole seat arrangement now. Monitor is not a problem as I use a VR now. Lets see how this goes.
  12. MarkusB

    MarkusB Active Member Gold Contributor

    Joined:
    Jun 30, 2015
    Messages:
    334
    Location:
    Germany
    Balance:
    2,403Coins
    Ratings:
    +281 / 1 / -0
    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    Yes, just try it. You can still reduce the movement via the Axis Limiting within SimTools.
  13. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    Next steps done, rod ends mounted to seat base plate. As I use a real car seat (which can recline) I can't use a shoulder mount. Also motors and levers with 28 mm CTC ready for mounting.

    Seat with rod ends.jpg Motor with Lever.jpg
    • Like Like x 2
  14. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    As my wheelchair motors only have a drive shaft on one side of the gearbox I needed to add gears on the shaft to drive the hall potentiometers. I hope this does not add to much slack.

    Potentiometer gear.jpg Potentiometer gear top view.jpg
  15. GTexas

    GTexas New Member

    Joined:
    Mar 14, 2017
    Messages:
    21
    Location:
    Houston, TX
    Balance:
    294Coins
    Ratings:
    +5 / 0 / -0
    My Motion Simulator:
    2DOF, 3DOF
    First motion tests done and preliminary PID parameters for no-load set. Kp values of 250 and 200 were sufficient with no load.

    M1 Test_s.jpg M2 Test_s.jpg

    M1 Square.jpg M2 Square.jpg

    M1 Motion.jpg M2 Motion.jpg

    Next steps: connect motors to seat, adjust hall pots to neutral position and tune PID under load
    • Like Like x 2