Showroom 6DOF Stewart AC Servo Motion Helicopter Build

My plan is to build a helicopter sim, as I can't justify the cost of a real licence at my time of life.

Its based on Knaufinators' build originally, and decided that as a lifelong workshop machinist the metalwork was pretty much a done deal, and if I managed to get the PC linked up to the Servos with some resemblance of sensible output, then I was as good as there. I chose Chris' design as it is open source, with enough info to make the whole thing, parts lists, program code, circuit board layouts, frame dimensions and much more. You have to have a little bit of electrical & programming savy to know what to do with it all, but it is all there.

As the servos were connected and the power supply was begining to come together, I looked around the forums and saw Smitty's build. His build IMO is in a perfect world, the way we would all like to persue our dreams. I don't have access to CNC machines, am limited with time and have somewhat limited funds.

However I plan a helo cockpit, and have explored a projector based system.

This is where I entered Chris's page, and start my journey.
This is the last post on his page after which I will add further progress here.

Regards
GB

So I have a little update on the progress so far..
Started the screen build.

Decided to use unistrut for the stand, as I'm not sure if this is what I want, and the outlay isn't too bad.
Used a spreadsheet (available online) to get ideal angles etc for screens.
However, I somehow managed to break one of the screens


Put rubber bushes on the base to take the servos.



Added the motors... more screens, and an arm on one of the gearboxes.



Loads to do but I'm making progress. Once the top frame is on (standing up against the table on the left), it'll be time to connect up the power. Even painted the floor to make it look tidier.
PC arrived, but still needs putting together.

Wow, your screens and the pushrods look really BIG. Do you plan to move the 4 screens together with the rig? I'd be afraid of breaking them, well you already found out that such large flat screens are not very rigid.
For such a big simulator, a beamer (or several of them) might be a better choice. A canvas screen doesn't break if bent and the picture doesn't change much even if the support is not very stiff.

Check out @GRAP's projector setup and @peter stolmeier's project.

I wasn't planning on it, but if I build the cockpit (helo) I can use the external view only, and ....thats it, still experimenting really.

More progress, I added the top frame & seat for a photo op. I need to get it all wired up to setup the servos.

Wow, that's really impressive, 6 screens! With that large area the immersion effect should be good enough even without the screens moving. The frame-gaps between the screens might be a little distracting, though.

What graphics card are you using? I haven't seen one with more than 4 ports, yet.

Wow, yeah those rods look 2x as long as they need to be

Main bits....
Gfx: RTX 4080 super trinity black
Proc: AMD Threadripper PRO 5955WX
MB: Asus Pro WS WRX80E-Sage.
Using a video wall control for the six screens which only uses one output from the GFX card.

Well, I did use the spreadsheet and online calculator to work out all the sizes. Will post details when I get home. Now that you've said that I'll have to recheck.

Ah, interesting. Then, are you still able to control the view angle (I think it's called multi-view) for each screen sperately or does it just act like one big flat screen?

There's a rotary spreadsheet calculator?

When all the servo arms are in the lowest position, all you need is minimal clearance from the top of the drives to the bottom of the moving platform frame. Anything higher than that is wasted space, and possibly more dangerous.

It will work as you have it, but the extra height just makes it more susceptible to tip-over. Your base is similar to mine (love the inverted foot mounting btw), and my servo arms are 200mm with 550mm ball-to-ball rods. Even at that height, with sudden moves, the base has hopped around. If those were ~300mm longer, it would be truly scary. Plus youll need a ladder to get in!

Below are my measurements in full down position. In hindsight, i wish i made my rods just a bit shorter even, maybe 500mm, or sunk the chair down lower into the tube frame. It's juuust a little high to smoothly get in and out of.



And this rear view is at 'center height' where all moves start from. The base width is approx 1030mm and the red triangle is to the upper platform CG (with me in it). The taller you make that triangle, the easier it is to tip over. an equal 60deg triangle would probably be best.



Stay safe! You will find it is a powerful machine.

Not too sure of the details yet, as I haven't had time to play with it. Although I did have to flip the top three screens 180, as my top screens are upside down (to get the smaller bezels closer).

This was the model

I believe so .. (compliments of the @knaufinator)
https://onlinegdb.com/muCwqMFO_

and use the fork button to allow you enter your own dims...
here's my entries. The idea is to get the Alpha output as close to zero as possible.

Code:

static float theta_r = 17.0; // the angle between two connecting points on the upper chassis. the angle is measured from the center of the upper circle. .. the connecting points all exist on the same circle.
static float theta_s[6]={150,-90,30,150,-90,30}; // this is the position of the arm/motor
static float theta_p = 60.0; // the angle between two servos along their axis, from the center of the base circle.
static float RD = 17.23; //radius of the base/motors connecting points
static float PD = 18.55; // radius of the platform connecting points
static float ServoArmLengthL1 = 8.00;
static float ConnectingArmLengthL2 = 30.53;
static float platformHeight = 22.000;

My output using these dims (in inches) was:

Alpha
-0.0005580596,-0.0005581306,-0.0005581306,-0.0005581306,-0.0005581306,-0.0005580596,

Very true, hence I changed from m12 to m16 rod ends, and for longevity too of course. Actually I'd like to get some dust covers, so that I can grease them up.

As per your comments, I think I may have to bolt it down too. Edit: Especially as I've seen your 'Bad Landing' video.

PC tower turned up today, so that'll be this weekends job. If it'll probably take longer than that.

So windows 10 or 11?

Fractal E-ATX case

Guess mine's ok, but from what i can determine all alpha=0 is just telling me is that at midpoint the rod and arm are perpendicular? I can plug in some ridiculous numbers for the last 2 and get even closer, doesnt mean its any good

Ok, as long as you are happy, thats all that matters.
This was my starting point, and Chris' model seemed to work fine, it seemed like a good idea to comply.
I still think I'll need to fix it down especially as I plan to build a helo cockpit on it.

Ok. It seems that the 6 screens are than handled as one big flat screen on the PC side. This means you can't use them for multi-view where you could set the viewing angle seperately for each screen to account for the mounting angle of the 4 side screens. There is extra software like fly-elise to fix this. It can be used to compensate distortions or to split a screen into several sub-units. But it costs money and has a CPU/GPU load penalty.

I didn't feel I needed to. Although I have looked at Fly-Elise, and others, and would have done it had I actually gone for the dome & projectors.
I used this spreadsheet for the screen angles... although when you move about you won't remain at the ideal angle, but hey I gotta start somewhere.

@smitty, I've just had a binge watch of your videos, had a great at some of the antics. PMSL.. thanks for sharing

Little bit of progress....

So the E-ATX case I bought for the PC only took a mobo up to 280mm wide, but mine was 330!!
Now I could, I suppose have packaged it all back up arranged for collection and searched again, but...



I drilled out the necessary rivets, and needed to move the raised section 30mm to the right.
If I cut along the bit where it goes up, and again 30mm to the right and spin it around?





Add a lick of paint and some extra standoffs. Not the prettiest, but never to be seen again.

Wrong!! With mobo inserted, I can't get access to the plugs that need to go in the bottom edge of the mobo!!



So more drilling, more cutting, and more paint, sorted.



Finally.....





Now onto the power side of the project
Cleaned up the donor panel, and removed stuff ...



Then on the base plate, its a case of out with the old ...



and in with the new...



now for some cable management on the servo side.... I think the servo to motor cable can be seriously shortened, as they are right next to each other, and the ribbons cable remade to round (black) cables.

Has anybody noticed the motors getting warm? as I was thinking of adding a fan in the centre of the base frame hole (at the bottom) to get some airflow.