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DIY 360 Degree sim

Discussion in 'DIY Motion Simulator Projects' started by A Ro, Jul 27, 2018.

  1. A Ro

    A Ro New Member

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    My Motion Simulator:
    AC motor
    Hi! I'm a 20-something guy a couple months or so into a 360' sim. I'm green to sims to I hope that's the right terminology. I have a very rough idea of what I want as far as shape, form and function goes, and despite being relatively well-versed in CAD have mostly stuck to pencil and paper for design.

    It has a pitch and roll axis, powered by two 2kw AC steppers through 30:1 and 40:1 worm gear reducers, respectively. As it uses slip rings to transfer primarily power through the rotating parts, it can roll/pitch infinitely.

    The pitch axis has two 110v legs, a neutral, and a 12VDC 'kill switch' signal that when triggered physically cuts power to both axis drives. Said kill line has two switches on the vehicle, one a pushbutton behind the throttle and another as a kind of ejecty-pully-cable between the operator's legs.

    Both axes have been tested manually (jog function of the drives) with up to 250lbs of human, and I've found I need to do a lot of hardware limiting of the drive components, as especially with the momentum of the pitch assembly, with a 20% exceeding of maximum weight (300lb + dry weight of the pitch assembly itself), it can crack and just about explode the reduction drive. The pitch drive assembly is the real challenge here, but as it stands it can well stand the movements needed for the intended flying game (war thunder).

    Each axis has an independent controller (ESP-12E 8266 + NRF24L01) that communicates with the drive over serial and receives instructions over 2.4ghz from a main controller (pi 2 B) on the vehicle that takes instruction from SimTools over Serial. Getting the latency on this whole trace (sub-40ms) has been a challenge, and is my current activity. The neat parts of this approach is it obviously hugely reduces the wiring loom that needs to pass through the axes (which at that point would make slip rings not cost-effective), and in addition, the entire control assembly (laptop, copy of control surfaces, copy of main controller) can be removed and run the machine remotely for testing.

    For screens, I'm eventually going for a VR approach but am holding off on deciding the oculus/Vive thing until everything else is done. On initial observation, neither of those platforms enjoy being upside down as far as how they're worn goes... Both have some workaround way to get the head tracking to work in a way relative to a non-stationary platform. The onboard PC is a VR-capable laptop I had - Things like the tactically-canted mount for it and 110v receptacle exist to be able to attach/disconnect the laptop from the sim simply-ish.

    I have a whole google photos album - not sure the best way to share that here. I've still got a month or two to go before I'm up, flying, and as a function of motion sickness or catastrophic structural failure, regretting building it.. I've had tons of fun so far

    20180727_140841.jpg 20180727_140826.jpg

    Progress to come depending on when I get over the guilt of it being so nice out here! (Western WA, USA)
    • Like Like x 5
  2. SeatTime

    SeatTime Well-Known Member

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    My Motion Simulator:
    AC motor, Motion platform
    Hi
    Plenty of challenges and compromises in building a 360 degree capable sim. Good luck:thumbs. Look forward to seeing any updates.
    • Agree Agree x 1
  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    You could share a link, but in terms of member interest it would be good if you can select some photos that clearly document the different as part of the build phase.

    A 360 degree build is not common so members would likely be interested in related aspects such as what slip rinds were used and their integration into the project.
    Last edited: Jun 24, 2021
  4. A Ro

    A Ro New Member

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    My Motion Simulator:
    AC motor
    All of the photos in the album are annotated, so that'll help a bit. As far as slip rings, this 20180705_231528.jpg would be an example use of a slip ring that's intended for small wind turbines (link posted at the foot). Their only 'limitation' is 250rpm, but if you're even considering being in the ballpark of that on either axis, that'll be the last of many components that will fail. These rings are significantly less expensive than industrial ones. For my pitch drive shaft (1.75OD/.375wall DOM), I had to shave a bit of the outside of the ring down to have it fit in there (yet not distort the housing to the point of putting more stress on the brushes within the ring).

    The suite of C programs that runs on the main controller continues to be the focus of time on this. A consideration right now is whether to break each 3 out into independent programs (Interface with PC/Simtools, GPIO interaction with panel, Communication with axis transceivers) that communicate over domain sockets, or just pack it into one big monolithic program. The disadvantage of the monolith being that each 3 need to integrate some sort of blocking loop, so that'd need to involve some threading. Trying to black-box what seems to be a bug in SimTools' serial interface, but alass it's closed source :(

    http://webcache.googleusercontent.c...69i57j69i58.1733j0j4&sourceid=chrome&ie=UTF-8

    https://en.wikipedia.org/wiki/Slip_ring
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    If you have found a SimTools bug or need advice then please state what it is and how it can be replicated, as the SimTools developer @yobuddy is very responsive and helps out as much as possible.
  6. yobuddy

    yobuddy Well-Known Member Staff Member Moderator SimAxe Beta Tester SimTools Developer Gold Contributor

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    • Informative Informative x 1
  7. A Ro

    A Ro New Member

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    Awesome! Good enough time as any to knock the dust off of my VS install and get out of C land for a while :)
    • Like Like x 1
  8. yobuddy

    yobuddy Well-Known Member Staff Member Moderator SimAxe Beta Tester SimTools Developer Gold Contributor

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    @A Ro,
    Maybe you could share what problem you are having buddy?
    Might be able to save you some time.
    yobuddy
  9. A Ro

    A Ro New Member

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    @yobuddy Sorry for a super late reply, but I'd dug into that a fair amount and come to the conclusion that mt PL2303 chips that I was using to do the USB-UART thing were counterfeit and as a result the Prolific drivers were being downright evil. Things have calmed down now that I'd found a few genuine chips.

    On a more broad note, this is far from a forgotten project, as it's footprint still occupies 1/4 of my shop and 100% of my auto lift's usefulness. Life had it's way with my time, but I've been making progress on the supporting code for the controllers (https://github.com/alexanderross/flightsim). Mechanically, we're just about there. I'm waiting to come across more sheet metal to prevent legs/feet from slipping out of the cage and possibly becoming separated and/or maimed which is looking like it could be an issue.

    I have an annotated photo album right here - https://photos.app.goo.gl/GPJkN2BUhSPLfer26 which allows me to much more easily post video
  10. A Ro

    A Ro New Member

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    My Motion Simulator:
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    To bring this back from the dead - I completed this sim - . Though the top lesson is for flight, it's inherently motion limited (eg. In the aircraft, pitch straight up, roll 90, then pitch back to level, what does the sim do?) Had to do some interesting patching/shimming to fix, but it was a big compromise to the immersion.
    • Winner Winner x 2
  11. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Given how often 360 degree sims are discussed, but rarely built, it is great to see yours in action, compromises and all :thumbs