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New, lighter 2DOF simulator.

Discussion in 'DIY Motion Simulator Projects' started by tahustvedt, Nov 3, 2017.

  1. tahustvedt

    tahustvedt Member

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    I'm back. :)

    This is my old simulator: https://www.xsimulator.net/community/threads/my-2dof-diy-sim.3646/


    I had to take it apart when my sim racing interest dwindled a few years ago because it took up a lot of room, and I needed the materials for another project. Now I'm interested in racing again though and would like to make an improved version. I have kept everything that I didn't use, except for the bucket seat, which was too heavy anyway at 10 kg.

    I want the new version to be much lighter. The first one was very stiff and strong, but weighed 100 kg. I will use plywood and carbon fiber this time, and will use Oculus Rift instead of three monitors. The seat is one that I made for my velomobile a couple of years ago but replaced with a newer version. It weighs just 2,7 kg. I will add padding to it.

    I will also make this one fixed so that I can not change the point of rotation down to my chest for flight sims, as I never used the old one for that anyway. The center of rotation will be 1800 mm up from the floor to ensure correct G-force simulation, like shown in the video above.

    I have a new idea for actuators. I will use the motor from the old winch units and drive the axis through a belt system made from car timing belts. It will save a lot of weight if it works. There will be skate board wheels for motion with support bearings on all sides. Total motion will be 9-10°, which is actually slightly more than I had on the old one. Unless something better exists today I will use Pololu JRK units for motion control.

    The drawings are not finished. They are work in progress, but show the old one next to the new one, and the lightweight seat. The seat has side support in real life, but I didn't bother modeling it perfectly. (Bucket seat model on the old one is from Attila as I couldn't be arsed to model one: https://3dwarehouse.sketchup.com/model/106d99a8c011009f494ca17f7261d31a/BRIDE-bucket-seat )

    In addition to a much bigger CNC router I now have several 3D printers and am able to make even more advanced parts using CNC.

    Attached Files:

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  2. tahustvedt

    tahustvedt Member

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    I have had this idea ever since I started with the first sim, but decided against it as a first build because it's not stable without power. I'm revisiting the concept now though and even ordered some universal joints so I think I will go with this approach this time instead of the "bowl" rails. The rotational point is still at the same height above my head, but it also moves me slightly down towards the edges of the movement, which probably is a good thing for enhancing the feeling of G. It's much more compact and easier to build, but requires me to rethink the actuators.

    Attached Files:

  3. tahustvedt

    tahustvedt Member

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    All three arms prevent torque, while allowing for 2DOF motion in an arc that both produces G by motion and angle changing.

    Here's a little proof of concept model I made using RC car CV axles.
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  4. tahustvedt

    tahustvedt Member

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    I checked my old servos made from winch motors, and they are good. There's hardly any backlash at all in the gears wit the custom gears in place, so they will work fine. I used them with 240 mm long arms on my old sim so they are incredibly strong. The large gears for the first two stages are delrin. All the other gears are steel.

    Worm gear motors would probably be a good idea though since the sim is unstable when not powered.

    Attached Files:

    Last edited: Nov 4, 2017
  5. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    My Motion Simulator:
    3DOF, DC motor
    Interesting concept, I look forward to seeing where it goes!
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  6. tahustvedt

    tahustvedt Member

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    Here's roughly how it's going to move. When it moves forward it also tilts me backwards, and vice versa, for both rotational and linear G-sensation. The same for left and right roll. I think it will work well, if my servos are up to it. Moving away from center also moves me up and down slightly. I don't think this side effect will be big enough to affect the sensation negatively. It's possible to reduce this effect to almost nothing by using very long arms, but it would also require a very large base to prevent it from tipping over. :)

    I'm also playing with the idea of moveable bottom mounts to give me different rotational centers for car and aircraft simulation.

    I don't want to fabricate any parts until I have some uni joints on hand. I can't even finish designing until I know exactly how the parts I have ordered look in real life. For now I can only figure out the rough geometry.

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    Last edited: Nov 8, 2017
  7. tahustvedt

    tahustvedt Member

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    I just learned that the Oculus Rift doesn't work well with motion platforms since the update in february/march. That sucks and puts the whole project in jeopardy.

    Which VR headset will work on a motion platform. Pimax 8k?

    Still waiting for critical components to arrive so I can get the dimensions I need, but I am playing with different solutions. I think I will try to make the whole cockpit out of carbon fiber tubing for reduced weight. Only roughly laying out the structure at this point, nothing final.

    I made a flight simulation cockpit for Aerofly FS2. I made 3D printed gussets and 20x20 mm carbon fiber tubing from Hobbyking to build it, and a Logitech Extreme 3D joystick as the basis for the controls.

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    Last edited: Nov 30, 2017
  8. Mat_Menzies

    Mat_Menzies New Member

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    Hi tahustvedt, I'm embarking on a 2 or 3 DoF rig with pivot point at my head and I was happy to find your previous iteration and concept designs.
    Do you have any further progress of your designs? I'd love to see what you have achieved.