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My DIY 6DOF - 80/20 - AMC - Clearpath Servos

Discussion in 'DIY Motion Simulator Projects' started by Nisch, Jun 4, 2019.

  1. Nisch

    Nisch Member Gold Contributor

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    So I purchased my AMC1280USB 2 years ago with the intent to build a platform, but wrestled with whether to build a linear actuator setup or the lever setup. I knew I did not want to go with the potentiometer feedback style system, so the idea of servos became an interesting option for me.

    Through lots of stalking various threads here and on the motionsim forum, I noticed Teknic put out a new operating mode for their MCPV servo models. I purchased a NEMA 34 size and a 56c-size motor along with an 80:1 wormdrive gearbox as well as some ballscrews for the linear setup. I liked the 34 for the smaller size (more for linear actuators), but I really liked the idea of the straight AC hookup on the 56c size motor. Unfortunately the 34 size servo did not work when I received it and sent it back to Teknic for repair. Upon talking to one of the engineers at Teknic, I tried the "Follow Digital Position" setup for the larger motor, testing it here:



    Then hooked it up to the 80:1, 75mm CD gearbox and tried it out hooked up to only 110V, resulting in a max of around 1000rpm. That's obviously too slow for the final setup, but with 220V attached, you have a max RPM of 2830, which reduces to ~35RPM, which I've read should be suitable for motion platforms.

    Here it is testing with the gearbox attached, connected to Thanos' AMC and using the Hexpod software:



    Once I decided that was going to work, I ordered the remaining motors:

    https://www.teknic.com/model-info/CPM-MCPV-N0561P-RLN/

    Following the design from this thread:

    http://motionsim.freeforums.net/thread/176/dof-step-diy-project-blueprints

    I started gathering the pieces I needed, welding together the top frame (albeit poorly as my welding skills are horrible) and the 6 connecting rods. I went back and forth on what I wanted to do for the base, but since I had a reasonable amount of 80/20 extrusion laying around, I decided to see what I could throw together with what I had:

    62005042_10214008338582776_8843947629424410624_o.jpg

    61984989_10214008337902759_3439669136467165184_o.jpg

    I don't have all the brackets yet, but put it together (from a dimensions standpoint) and added some cross braces (don't have the right ones yet, but just used what I had) and decided on using the 80/20 for the base. I ordered wider pieces for the main legs of the triangle (1545, 4.5" wide pieces, 48" long), and have tested cross feet to stabilize the base (not pictured).

    Since I'm waiting for the rest of the metal/brackets/bolts to show up, I hooked it up again to 110V and did a range of motion test with just one leg moving:



    I spent a whole weekend putting in a new subpanel in my basement, allowing me to run 6 dedicated 220v, 20amp circuits to my computer area. Once I get all of the layout for the base figured out, I'll dismantle it and move it to the basement for assembly in my computer area.

    I currently have an Obutto R3volution cockpit, but have since ordered a mess of 80/20 extrusion to create a new cockpit to put atop the platform once it's built. I have several shipments showing up this week.

    That's what I have so far. Once I get the rest of the metal pieces, I should be able to progress and hopefully have more pictures for you guys.

    Thanks to everyone for posting their projects and providing the motivation for building one of these.

    Dan

    Attached Files:

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  2. Nisch

    Nisch Member Gold Contributor

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    So I beefed up the base a bit with some wider pieces and got the basic assembly figured out. About ready to move it to the basement and get it hooked up for some testing.

    Figured I'd post a few pics

    20190610_221022.jpg
    20190610_221015.jpg
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  3. SilentChill

    SilentChill Problem Maker

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    35rpm ? That seems really slow unless you are just going to use it for flightsims ?
  4. Nisch

    Nisch Member Gold Contributor

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    I had also been concerned about that speed, but when doing the math on many of the other rotation style platforms, they've been using 1800RPM motors along with around a 60:1 ration, which puts their output at 30rpm. Given the fact that the arm only needs to move (slightly less than) 180 degrees, doing so in under a second would be good enough. My motors will do 2800 RPM, so coming in at 35rpm puts me a little quicker than the other platforms, but an increase in the output torque with the higher reduction.

    I can buy 60:1 gearboxes that would put me at around 47rpm. Would that be a better option? (minus the extra $2400 that it would cost me, lol)
  5. SilentChill

    SilentChill Problem Maker

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    I thought around 60rpm was the lowest people recommended but I guess it depends how long your arms will be from the gearbox. If your getting between 250mm/s to 300mm/s at your lever end it's all good
  6. Nisch

    Nisch Member Gold Contributor

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    @SilentChill I appreciate the feedback. I probably did screw up with that. I would like to use it for racing as well as flight, but was going from the BOM of the post I saw on the other forum where the 80:1 gearboxes were used with even slower motors and it seemed to move him quite well. In hindsight, I probably should have sat down and done the math for that. At the very least I can get this up and going, figure out what my end result load is and see what my gearbox options are then.
  7. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    You can use this calculator to work out the lever linear speed: http://www.endmemo.com/physics/rpmlinear.php
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  8. Nisch

    Nisch Member Gold Contributor

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    Thanks for that link. According to that calculator, I should be at 586mm/s

    Will that be suitable?
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  9. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    Yes 586mm/s should be fine, even for very fine racing movement simulation.
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  10. Nisch

    Nisch Member Gold Contributor

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    I appreciate the link. I'm auto-tuning the motors right now, so hopefully I may have some testing done tonight with the AMC hooked up.
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  11. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    500mm/s is perhaps a little too much for 6DOF... See how fast 500mm/s is here (see from min 2:30):



    But you can always adjust the max motor speed of the clearpath servos...
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    Last edited: Jun 12, 2019
  12. BlazinH

    BlazinH Well-Known Member

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    That calculator only tells you the maximum speed possible though and its only possible at one point in the rotation the way we use them. So in actuality it will be less.
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  13. Nisch

    Nisch Member Gold Contributor

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    Got some more progress done on the platform. I got the AMC hooked up, homing sensors installed, homing sequence calibrated and Hexpod software tied in. Also got the new cockpit built out of 80/20 with both flight and race attachments (flight pedals not installed in picture)

    So far so good....

    20190615_094903.jpg





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  14. Nisch

    Nisch Member Gold Contributor

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    Got the cockpit clamped in place. Welding tabs on tonight to secure it.

    Edit: TIG welder died after welding on half of the tabs. New one will be here Monday

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    Last edited: Jun 16, 2019
  15. Nisch

    Nisch Member Gold Contributor

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    Got the cockpit mounted on the platform and worked a lot with @Thanos with the controller and plugins. Got the @pmvcda plugin working and did some testing with iRacing. I obviously need to do a lot of tuning, but it was an absolute blast getting to finally experience anything.

    The girlfriend took it for a quick test

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  16. Nisch

    Nisch Member Gold Contributor

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    Here is another quick video of me driving. I barely slept last night wanting to go downstairs and play on it. Have the VESA mounts coming today to mount the (3) 32" curved monitors to the setup.

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  17. Razvan

    Razvan Member

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    That's a cool ride man !! also, looks hot and light,
    with all the aluminum :)
    I'm trying to figure out the profiles you're using, and I'm missing something out.
    (As I write these words I understand... 8020, not 2080.. self-face-palm),
    So I'll go to my next question:
    do you have an estimate of the total length of profile used?

    Also, the brackets-screw solution, does it hold after all the shaking and movement?
    or do you need to re-tighten them every now and than?
    It looks wonderful, but my lack of knowledge and experience makes me wonder
    if it doesn't get loose.. or something..
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  18. Nisch

    Nisch Member Gold Contributor

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    In regards to the profile used, for the base, I'm using 15 series. 1545 for the main base components (1.5" x 4.5"). I chose this because the gearboxes are approx. 4.5" wide. Then I used 1530 for the "T-legs" underneath (1.5" x 3") and then 1515 for the inner triangle brace (1.5" x 1.5"). I refer to it as 80/20 because I use aluminum profile from 8020.net, but I'm using the fractional extrusions, not the metric.

    For the 1545 pieces (the main outer triangle under the motors), those are 48" long. Taking into account the brackets holding the gearboxes on, it puts the motors at 910mm apart from each other, which was exactly what I was going for (basically the shafts are 36" apart from each other). Being a triangle, that was 3 total pieces of 1545 for that component.

    For the "t-legs" underneath, those are 12" pieces I just had laying around I want to increase the length of these to increase the stability a bit, but they're 1530 pieces, 12" long, 6 total.

    for the inner triangle brace, I'm using (3) 40" long pieces of 1515, With that length, it puts my spacing between the output shafts at 500mm.

    In regards to the profile used for the cockpit, I followed the plans here (the top "Low and Light" design, low isn't an option since it's 3 feet in the air and light was the goal):

    https://i.imgur.com/AsxPuja.jpg

    I played for a couple hours last night and did not experience any screws coming loose. I do have to add some bracing to the base to minimize the slight flexing it is experiencing. I just am going to add braces between the tops of the gearboxes and that will solve that problem, for the most part.

    I also have thread locking compound that I will be putting in everything once I settle on the design and don't intend on changing it anymore. I'm about 235lbs and it feels quite solid with me in it and I will be able to achieve only so much rigidity because I cannot bolt it to the concrete (like many people do, such as @Trip Rodriguez does). My basement has in-floor heating, so I can't run the risk of damaging the heating lines in the concrete. So my option is to build it wider with the t-legs underneath each main portion of the triangles and add bracing to the tops of the motors (which it would appear everyone does anyhow).
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  19. Nisch

    Nisch Member Gold Contributor

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    Just for the record, I would build the base out of welded steel if you have that option. The 80/20 aluminum ends up being ridiculously expensive compared to what a steel base would be. I had a large amount of the extruded aluminum already laying around, so I just worked with what I had.
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  20. Nisch

    Nisch Member Gold Contributor

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    Made a little more progress today. Added more to the cockpit to allow for monitors to be mounted. Only one is mounted so far because I need to work out the support for the side monitors. Also installed a 4 point harness and did a little but if tuning with the @pmvcda plugin. I also redid the tuning procedure on the Clearpath servos. It lessened the clunking quite a bit. Between that and the filters with FlyPT, it improved the smoothness greatly. I upped the sway/surge/heave from 50 to 100. The other DOFs are still set to 15 each.





    Next step is other monitors and bass shakers.
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