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Showroom FlyPT - 6DOF Brushless DIY Actuators

Discussion in 'DIY Motion Simulator Projects' started by pmvcda, Aug 29, 2017.

  1. SeatTime

    SeatTime Well-Known Member

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    This concept of height related heave really interests me - even as a mix to normal heave :think, so I'm going to look into it further... may be a dead end, but you never know.
  2. BlazinH

    BlazinH Well-Known Member

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    I don't really get it but who knows for sure until its tried. If anything though big heave is important for simulating turbulence. And the more range you have the more you have room for washout. At least that was my experience on the first rig I had that had 375mm of heave and was designed for flight.
  3. Trip Rodriguez

    Trip Rodriguez VR Pilot

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    Yes, I don't think I agree entirely, but I do think you are likely on to something here.

    Before I get into the wall of text; do we not have the ability to have a G-seat give a continuous heave cue during a climb with our current software and telemetry? I assumed that we could.

    The feeling of vertical accelerations in light planes is one thing I have experienced quite a few times and I feel like I remember it crystal clear. Unfortunately I don't remember it nearly so clearly in helicopters, which means I need to somehow get another helicopter ride! I do remember at least one occasion of hitting a sudden thermal or wind shear in a helicopter and getting the same feeling, but aside from that I think vertical accelerations were a bit less pronounced than my GA and glider flights but as I said I don't remember it clearly.

    Anyway, IMO the feeling in very light fixed wing aircraft is almost identical to a fairly fast passenger elevator, like those in hospitals for example. Mostly I feel the acceleration upward, then not a whole lot, and then the downward acceleration when the climb stops or reverses. This feeling is present at liftoff, hitting thermals/turbulence, and with significant pitch control inputs. My 15" of travel does this fairly well, except the duration is not as long as I'd like it to be because I run out of travel. The sense of continuous steady R.O.C. I think is pretty subtle to my senses, whereas the accelerations (changes in R.O.C.) are a key element to the 'sense of flight' in light aircraft.

    Now, I've never been in any jet that wasn't an airliner, so I have no real idea what that feels like. I do feel like what I describe happens in airliners to some extent. The way I remember it, liftoff is lesser in intensity but longer duration feeling of upward acceleration and tends to fade away into something like you describe in terms of the sustained climb cue. I don't think there is usually that downward accel cue like in very light planes. Turbulence I've experienced in Airliners I think I remember being much shorter duration and strength, but higher frequency up and down accelerations the point where they sometimes feel more like bumps in a luxury car.

    I'd welcome any opinions from pilots of course, counter to or in support of my description. I've only got five GA, 4 helicopter, and around a dozen airline flights in 737's and Dash-8's. Four out of the five GA flights were instructional flights in a Schweizer 2-33 with air tows, that's my only real life stick time.

    I do not assert any of this to be correct, just my attempt at an analysis of my few personal experiences.
  4. pmvcda

    pmvcda aka FlyPT

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    Progressing, but missing cable management, seat adjustment, replace some nuts on the pedal and cut extra length in screws....
    Dismantle one actuator that is making a strange noise. Think that top spacer of the ball screw has fallen and must be broken inside the tube...
    Current state:

    IMG_20191016_170431.jpg
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  5. PeterW

    PeterW alias Wickie

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    Hi FlyPT!
    Thats a really amazing looking sim so far!
    Regarding the wheelbase and the pedals I think you made an absolute great choice! The Heusinkvfeld pedals and the simcube (pro? or sport?).
    Thats exact the same I intend to buy for my sim - in case its raining money :grin
    Wickie
  6. pmvcda

    pmvcda aka FlyPT

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    It was supposed to be DIY...
    At least they feel great (at touch, because I did not test them yet)
    Well, I deserved, because I had a G25 from when they where released...

    EDIT:
    It's a SimCube2 Pro with an Ascher plate and OMP wheel.
  7. pmvcda

    pmvcda aka FlyPT

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    Ok, some ridiculous videos...
    Forgot to change audio level for the micro, so I just added some music.
    Will make better videos.

    Video #1: Some slow and fast rotations with Mover:


    Here we can see that using the current position with forward kinematics for VR motion cancellation is a NO. See at 2:10. The rig can't follow the calculation it's impossible.

    Video #2: Playing with frequency:


    Can achieve some interesting results. I'm so sorry for the lack of sound.
    I can feel vibration in an efficient way down to at least 4 ms.
    But I was using a low resolution timer... Another thing I forgot.

    I will make new videos when I can and with better image.
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  8. hannibal

    hannibal Active Member

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    hey @pmvcda , i like to ask, what is the size of the metal tubes that you used to assemble your top frame? thickness of your rectangular tube? appreciate any info..
  9. pmvcda

    pmvcda aka FlyPT

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    It's a 40 x 40 mm section with 3 mm wall.
  10. hannibal

    hannibal Active Member

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    thank you.
    are you using steel or aluminum.. your build is shiny.. :)

    im planning out my top frame.. are there pitfalls that you suggest avoiding?
    i never welded before, im depending on friend to do the weld.. but i will cut the materials and tubes to be welded... cross my fingers in coming weeks..
  11. hannibal

    hannibal Active Member

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    just watched your video.... i am amazed.. wow..
    just wow.

    grateful that you share your FlyPT mover ultilities. i hope to play around with it by years end.
    may i ask if you have the dimensions of your top frame?

    not sure if i can see milimeter/inches unit of measure in your skectchup file...

    :) :) :)
    Last edited: Oct 23, 2019
  12. pmvcda

    pmvcda aka FlyPT

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    Sorry, just aluminium.

    Did not make the welds also. I asked a guy that works just with aluminium to make them.
    I wanted it to be strong.

    Pitfalls:

    - Go back some posts and you see some talk about loads on those welds and the risk of cracking with the load + vibration.
    I'm looking at it, if needed, I will add some triangles to support it.

    - Access to the rig. Be sure you have an easy access. Mine is low and the only problem I have to seat is the seat itself.
    It's a comfortable position, and seat although rigid (I wanted it to be that way to feel all the vibrations), but the sides are pretty high if you look at the pictures.
    That doesn't make it easier to enter.
    I copied the measures of the car in the back...

    - I saw that you have a kind of steps to help enter the rig, I think they will colide at certain angles with the actuators.
    My rig colides with the actuators, but you need to go to real extremes for this to happen. I limit it in the software.
    Test it with Sketchup or something similar.

    - My measures are on the Sketchup file. But they are made for me and based on the car, so it's small. Be aware of that.
    I just collected them for Sketchup and asked to cut the parts with those measures (no need for more than mm on precision).
    • Informative Informative x 1
  13. hannibal

    hannibal Active Member

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    thank you for taking a moment to reply... all your videos.. amazing!
  14. pmvcda

    pmvcda aka FlyPT

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    Thank's, not so amazing, but well, at least you can see it moving.
    Ask anything. :thumbs
  15. Flymen

    Flymen Flymen Gold Contributor

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    Hi , @pmvcda
    Can you add this video , on your set up page 1 , for more info : esp32 using Aurduino IDE | Solution for compiling errors in esp32.
    I had this problem … push and hold the boot button during uploading the program .:thumbs Thanks .


    The first one is finish and the second 60 %
    Need test it before finish other one...:think
    IMG_2100.JPG
    • Agree Agree x 1
  16. pmvcda

    pmvcda aka FlyPT

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    Posted in the first page. :thumbs

    I have an updated code for the ESP32 I will publish soon.
    Working at 921600 baud rate and with the 1 ms delay removed from te loop.
    Needs only 8 bytes to control the 3 actuators (15 bits resolution)
    Seems to be working good and smooth down to 1 ms calculation loop in Mover.

    To use UDP I need to change the board :( and we might need 3 ESP32.
    But before that, I want to test some solutions to avoid the 3 boards and maybe the new board... Let's see.
    UDP works with 1 actuator in the current board and it's as good as serial.
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  17. Thanos

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

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    You could use an ESP32 to handle only the wifi UDP to serial and transmit serial to the one that handles the motors perhaps? Wifi takes a lot of overhead for realtime processing...

    Actually that would be a good replacement for the USB for even my AMC controllers, they all have raw RX-TX pins that could be used with such ESP32 UDP bridge device...
  18. BlazinH

    BlazinH Well-Known Member

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    I don't see a purpose in adding something that may cause more latency and incomplete data other than the "cool" factor.
  19. Thanos

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

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    It might help with other issues like ground loops as well. Many USB controllers share ground with the motors through the metal frame of the rig, causing accidental ground loops if the controller or peripheral is poorly designed...
  20. hexpod

    hexpod http://heXpod.xyz

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    You should maybe consider the difference between the vertical speed (climb rate) and vertical acceleration which can’t be perceived if the climb rate is constant.

    In fact, I believe, you can climb with an aircraft without any additional vertical acceleration what doesn’t differs from still state on earth.

    You feel only the acceleration which is a changement of state. This changement of state in the aircraft can take from a fraction of a second to several seconds (turns, parabolic flights etc.)
    More heave you have more realistic the sensation will be although even with big heave you will never be able to translate strong vertical accels for more than a fraction of a second.

    I believe that’s what you call “an impulse”

    A pressure scafandre or belt tensioner stuff could help but will never take out the blood out of your head like inside an aircraft with strong positive G.

    A high performance Stewart will always be an aventage especially knowing the fact that using one DOF « eats » all others.

    From experience, even if your platform can do +-250mm heave alone, you will be forced to limit it to +-100mm which is not so much.

    I would love to construct a high performing compact rig which could allow you at the same time to pitch 20 deg with a room of +-200mm for a heave. I am sure it’s doable.

    If I design again a rig I would aim such a performance. I hope someone else will do it before me.

    Best
    Last edited: Oct 29, 2019