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.

Trip's G-seat project (primarily for flight)

Discussion in 'DIY Motion Simulator Projects' started by Trip Rodriguez, Nov 19, 2019.

Tags:
  1. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    Tonight I continued design work on my G-seat.

    I decided I'd been thinking about one of the cues incorrectly and most of my work up until this point was a wasted effort and I was slowly working my way back to a build near identical to Bergison's. I worked on drawing a different setup for several hours and working that drawing out made me decide I was correct in the first place, I had just been taking it a tiny bit too far.
    :think

    Have to sleep now, but I decided to make some notes before bed so I didn't forget the thoughts I had, and it turned into a very productive brain storming session. Funny how much writing things down helps me figure them out. I'm happy to say I think my setup will be at least a little bit unique. =)
    • Like Like x 1
  2. RacingMat

    RacingMat Well-Known Member Gold Contributor

    Joined:
    Feb 22, 2013
    Messages:
    1,943
    Location:
    Marseille - FRANCE
    Balance:
    18,316Coins
    Ratings:
    +1,858 / 16 / -2
    My Motion Simulator:
    2DOF, DC motor, Arduino
    good project! lot of thinking :)
    I'm intrigued: what is the animated picture in post #19? where did you find this?
  3. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    Thanks =)

    The GIF in post 19 is a drawing of my design for the mechanism for tilting the bottom seat cushion left and right like the ACME DMS while still having the heave functionality I created that was inspired by SeatTime's designs. I drew it with Fusion 360 and animated it with the same. It's my first project making a 3D drawing with moving parts. =)

    I'm still working on that drawing to build the full seat. I still have to finalize a design for the mechanism moving the seat back cushion and how to mount and connect the actuators to everything. It's driving me crazy with so many parts but this is a lot better than wasting materials figuring it out! I've been able to try a lot of design concepts with 3D drawings which allowed me to animate them and see if the design works etc. =) It's a fantastic tool, kudos to Autodesk for allowing hobbyists to use it for free!
    • Winner Winner x 1
  4. RacingMat

    RacingMat Well-Known Member Gold Contributor

    Joined:
    Feb 22, 2013
    Messages:
    1,943
    Location:
    Marseille - FRANCE
    Balance:
    18,316Coins
    Ratings:
    +1,858 / 16 / -2
    My Motion Simulator:
    2DOF, DC motor, Arduino
    great job! it looks so realistic :)

    one point in the design is to prevent play and backlash in the mechanism
    • Agree Agree x 1
  5. cfischer

    cfischer Member Gold Contributor

    Joined:
    Sep 7, 2015
    Messages:
    82
    Location:
    Colorado
    Balance:
    522Coins
    Ratings:
    +32 / 0 / -0
    Looking at your mechanism for moving the paddles at the same time in the z direction made me think of this mechanism. If you can get enough lift out of it you might be able to have a more compact setup for the same motion. Just thought I would bring it to your attention as I just found it myself and thought it was pretty cool.

    [​IMG]
    • Like Like x 1
  6. RacingMat

    RacingMat Well-Known Member Gold Contributor

    Joined:
    Feb 22, 2013
    Messages:
    1,943
    Location:
    Marseille - FRANCE
    Balance:
    18,316Coins
    Ratings:
    +1,858 / 16 / -2
    My Motion Simulator:
    2DOF, DC motor, Arduino
    @cfischer : looks good!
    but what are the specs?
    can you share a link please?
  7. cfischer

    cfischer Member Gold Contributor

    Joined:
    Sep 7, 2015
    Messages:
    82
    Location:
    Colorado
    Balance:
    522Coins
    Ratings:
    +32 / 0 / -0
    I mainly meant to share the concept so someone could make it themselves with the motors and angles that suit their project. I haven't even looked at the specs on that actuator. I found it through google image searches.

    https://www.google.com/search?safe=active&rlz=1C1CHBF_enUS876US876&tbm=isch&sxsrf=ACYBGNT80O2uSw3Co71BWXe-fjR_U_RgsQ:1575520668160&sa=1&ei=nInoXfGuCYi0tQXV4JTIDA&q=wedge+lift+stage&oq=wedge+lift+stage&gs_l=img.3..35i39.56649.61403..61543...2.0..0.66.1097.18......0....1..gws-wiz-img.......0i67j0j0i8i30j0i24j0i30.4ugcapklM-Q&ved=0ahUKEwjx7Ivu153mAhUIWq0KHVUwBckQ4dUDCAc&uact=5

    One could make this pretty easily with some cheap mgn12 bearings and a ball screw from ebay. Slap a 80ST servo motor on there and I bet it could lift your car tire pretty quickly.
    Last edited: Dec 5, 2019 at 22:48
  8. RacingMat

    RacingMat Well-Known Member Gold Contributor

    Joined:
    Feb 22, 2013
    Messages:
    1,943
    Location:
    Marseille - FRANCE
    Balance:
    18,316Coins
    Ratings:
    +1,858 / 16 / -2
    My Motion Simulator:
    2DOF, DC motor, Arduino
    thanks for the hint with the terms "wedge lift stage" for a non native speaker like me!

    that's a pity that the speed is 12mm/sec under a 20 kg load
    it's really slow but as I read in the specs, the main goal of this lift is micrometric positionning

    Attached Files:

  9. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    Once again, the more I work on the design and experiment the more I find myself moving back toward a design almost the same as either Bergison's or ACME's.

    This is going to be a bit of a rambling thought process so skip it, or strap in!

    I completed a design layout with all the features I'd decided to combine and with the animated drawing decided it was too convoluted, with too many redundant features. I think this is largely because of my decision to build the seat using only three actuators. If I can't move all these things independently there's a lot less advantage to having them.

    As for the two reference designs, I'm asking myself "why" the ACME G-seat is designed the way that it is. I think this is a good question since I suspect that a very large amount of money was spent on R&D in developing this system. The main conclusion I come to is that the design loses all it's benefits when you cut out the ability to operate the different features independently, so that sometimes two surfaces will move together and other times they move opposite.

    So, how best to achieve similar results with only three actuators.

    Design goals:

    1: Ability to feel the angle of a helicopter during pick-up and landing. Picking up you want to feel with great accuracy the direction the helicopter is tilting so you can compensate. This requires a pure "roll" cue, with the seat bottom and back rolling the same way and very minimal movement of the pilot within the seat.

    2: Best possible cues for sudden roll maneuvers in high performance aerobatic and combat aircraft.
    This requires the pilot feel violently thrown in the seat to the opposite direction of the maneuver. I want to feel myself being moved in the seat for this. That requires the bottom and back move opposite directions, or given my three actuator limit I think I can achieve this by rolling the bottom of the seat but making the back cushion stationary.

    3: Simulate pitch angle on the ground as with roll, and simulate pitch rotational rate changes in the air with an actual pitch motion.

    4: Simulate large forward accelerations positive and negative including aircraft carrier steam catapult launches and arrestor wire landings. This requires very fast and violent cues.

    To achieve both goals for the roll/sway axis I think I will have the rear cushion either roll with the bottom or just the cushion sway with the bottom roll (like ACME) up until a given point. Beyond that point the bottom continues to tilt but the back either doesn't move any farther or moves the opposite direction. The first part designed for subtle roll cues on the ground, the rest for bigger lateral-G cues. This is a problem to think hard about.

    For the pitch/surge axis I think things are a little bit simpler and that Bergison's system will do very well by itself without the need for any significant modification. For a catapult launch the seat violently tilts back, moving the pilot's eyepoint in the proper direction and the back paddles push forward as with SeatTime's designs to increase perceived force of the body being pressed back into the cushion. I've found the mechanics of this can be quickly complicated by complex designs intended to solve the roll problem described above.

    I think that Bergison's design of rolling the entire seat as one (and applying pressure with paddles) will provide the best cue for violent lateral G maneuvers and is also perfect for the subtle roll angle on the ground.

    I'm realizing more and more that Bergison's design is damn good. Really the only thing I feel it's missing is the feeling of friction of your body moving across the cushion since the cushion is moving with you instead of the reality where you are moving against it.

    To solve that I'm thinking about artificially creating a feeling of friction as the pilot's back moves laterally.
  10. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    More thoughts developing out of that:

    I'm going with the fighter jet here, since it's the tougher thing to simulate.

    If the jet rolling left violently is simulated by the seat rolling right violently the initial onset forces are reversed. This is the idea behind the ACME design. With that design the seat bottom moves with the aircraft, and the seat back moves you the opposite direction. A violent left roll has the bottom roll left and the back sway right.

    That is similar to what SeatTime was recently talking about with the bottom paddles in his G-seat actually moving the driver in the wrong direction during sway cues. He said that he may drastically reduce that paddle moving up, or even consider making it go the opposite way. The ACME seat actually does have it go the opposite way. I'm not sure about it feeling right after the initial onset, but again we are talking about a product the military uses heavily that is the result of many years of development and R&D.

    IDEA!: Hydraulic damper on the bottom seat cushion causes the bottom cushion to delay the "roll" motion, giving a better onset cue, but then a spring brings the cushion over to the "outside" of the roll for the sustained lateral G-force cue. Brilliant? Maybe!

    It would be better to have the bottom cushion actually move opposite initially and then go over... could I make that happen with only one actuator, and have it not interfere with the roll cues for helicopter pick-up? Need to think more about that for a minute.
  11. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    I think I might be onto something here with this use of dampers, and it so happens I've got three or so spare ones on hand. =) I've got a whole new concept to think through now. Various ways I might use a dampened cue, and various situations where it might cause a false cue.

    I think the dampers will be set fairly soft, so the delay it creates is pretty brief and basically doesn't happen during slow movements of the seat. The dampers I have are adjustable.
  12. BlazinH

    BlazinH Well-Known Member

    Joined:
    Oct 19, 2013
    Messages:
    2,051
    Location:
    Oklahoma City, USA
    Balance:
    14,962Coins
    Ratings:
    +1,714 / 30 / -1
    Imo 1 and 3 are easily and best handled by 3 dof motion (minimum). That's what I used years ago with FSX and it felt really good with helicopter flight and it was a blast. As soon as you lift off you have to start working the stick hard in order to keep it level and under control. When you land, unless you're really on top of things, you will feel varying degrees of bump and skid when you make contact with the ground or carrier. The only thing missing was yaw cueing.

    For 2, I will be releasing details on my G-seat possibly later today that will fill the void for sudden roll maneuvers. But its designed to work in conjunction with a motion rig so it may not be right for you.

    For 4, I will also be releasing information on my new g system for the head which is perfect for this. And this reminds me, I need to add some language to release me of liability from neck injuries when people like you want violence, lol.
    • Agree Agree x 1
    Last edited: Dec 7, 2019 at 15:44
  13. Trip Rodriguez

    Trip Rodriguez VR Pilot

    Joined:
    May 8, 2016
    Messages:
    542
    Location:
    Lake Ariel, Pennsylvania
    Balance:
    3,100Coins
    Ratings:
    +230 / 3 / -0
    My Motion Simulator:
    6DOF
    LOL too true. I never think in terms of liability when just having conversations and showing things we've done but you are correct we write things all the time that could be considered instructional to some degree. Fortunately for me my net worth would be less than the cost of their lawyer, blood from a stone and all that. =P I'd suggest adding it as a signature so it's attached to all your posts past and future.

    I'll look forward to seeing what ideas you share. I haven't talked about harness tightening, head loading, and probably some other things that I definitely intend to include but they will be present.

    Bergison's design is basically a g-seat with 3DOF built into it. Having the 3DOF move only the seat has the disadvantage of limiting the range of motion you can use, but the advantage of moving the pilot in the correct direction within the cockpit or car. Of course as always the ideal solution is "D" All of the above. =D