BYOMSA

[RandyT]

This is something I have been playing with over COVID lockdown.  It took a good number of months, off and on, but I think it came out pretty darned nice.

BYOMSA=Build Your Own Motion Sim Actuators 

Background:  I caught the Sim Racing bug a few years ago, and always felt like my rig was missing something.  I even went as far as mounting a low-profile powered subwoofer to the back of the seat to feel road bumps and engine noise, which works really well, but it still wasn't enough.

So I set out to see what was out there to get the rig in motion and I choked on my coffee.  4 actuator systems typically cost anywhere from 6000 to 12000 dollars. Obviously, hard pass.  Then I found the SFX-100 project, which can be done cheaper, but requires 2 solid weeks of 3D printing (day and night) to produce parts which are of questionable strength.  It also uses some not-so-easy to source and very large, square aluminum extrusions for the body.  Interesting idea, and many have done it successfully, but not for me.

So I did the research on what these things are, and outside of the planetary motor types, in their simplest form, they are just a hollow body, ball-screw connected to a servo motor, and ball-nut connected to a shaft with guide bearings keeping everything straight.  So I designed my own, which replaces the 3D printed parts with solid polymer sheet parts cut on my CNC router.  Two solid weeks of printing was reduced to a couple of hours fine tuning the cutting process.  The resulting parts are very strong, and easily resist the actuator bottoming out, with no damage.

I also did away with the extrusion.  In it's place is stainless-steel pipe with a much smaller footprint.  Easy to source, relatively inexpensive, and it should look good for a long time.  Getting a tube flat on the ends was a bit of a chore, but when I was done, I could stack all 4 tubes, with no noticeable deviation in straightness of the stack, or gaps between them.

There are lots of small, but important details in the design, but that's the big picture.

Of course, linear actuators are useless without the motors and driver boxes coupled to a controller.  While I was very tempted to start from scratch on the controller part, I decided to just use a canned solution.  The Thanos controller, while costly, is out-of-the-box compatible with the servo drivers I used, as well as with the excellent Sim Racing Studio software.  Most folks will use a server chassis for mounting all of this, but there was no way I was spending several hundred dollars for a metal box.  So I found a department store plastic milk crate knock-off I once had record albums in, and proceeded to modify it, in order to fit this 10lbs of expensive crap into the 5lb box. 

If you don't count labor, the total cost of the project was well below half of the least expensive ready-made option with identical specifications. 4 of these had no problem tossing around the rig, a driver, subwoofer and 50" TV, to the point that some of the screws on the TV support snapped.  I've since removed the TV from the rig and moved it to a stationary stand due to this.  The original setup was never designed to move.

Racing games on this thing are incredibly fun now.  Most racing games make telemetry data available to external devices, so pitch, roll, heave, surge, traction loss, etc. are all transmitted based on what is actually occurring in the game.  The SRS software has an additional "premium" feature, which allows the system to react to joystick position, but I haven't ponied up the $15 annual subscription fee to try it out.  Seems like a bit much to rent usage of an app which appears to hook game controls for positional data, but there may be more to it than that.  In any event, the first thing which came to mind for something like this would be to try it out with Space Harrier, Afterburner, etc...  I don't know if those games actually produced any telemetry data, but it would be pretty cool if they did.  This aspect is definitely on my to-do list, if I can find the time.

Sorry about the crappy photos...

[Vocalitus]

I always wanted to build a cockpit for games like Elite Dangerous and Squadrons and have it shift around like Space Harrier.

I do remember someone coming up with a similar experience with drill motors.

These are expensive but look the business.

[bobbyb13]

This is awesome.

How much seat time do you have in it thus far and how robust does it feel for long term home use now that it is done?

[Zebidee]

Very impressive. Glad to see you being pragmatic about cost. I too am interested in how durable it all is.

[RandyT]

I always wanted to build a cockpit for games like Elite Dangerous and Squadrons and have it shift around like Space Harrier.

I do remember someone coming up with a similar experience with drill motors.

So far, I haven't tried any flight games.  SRS has recently added support, via some third party code, for Squadrons and some other titles without native telemetry data.  ED is supported by some means as well.  I'll likely be tinkering with those at some point. 

I believe the drill motor approach uses brushless DC motors with position encoders.  While they are favored by some as being "smoother and quieter", they require some really beefy DC power supplies and are not nearly as plug and play as the AC servo solution.  The drawbacks of AC are possible EMI problems and motor whine, due to the high frequency power.  That said, I am running the whole system at 110v (dedicated circuit), instead of the usual 220v, and I have experienced none of those issues. 

How much seat time do you have in it thus far and how robust does it feel for long term home use now that it is done?

I'm guessing but between roller coaster sims and racing, I'd say there're about 30 hours on them ATM.   I actually waited for quite some time to talk about this, just due to not knowing if these things would kill themselves in a short period of time.   I'm happy to say that the actuators themselves are showing no signs whatsoever that they would be failing any time soon.   After a couple hour play session, the servo motors don't even get warm.  The rig is still rock solid on the 4 shafts (i.e. no "wear wiggle".)   I took maintenance into account with the design, so rebuilds will be quite easy.  The parts most likely to experience damaging wear can be replaced in their entirety at a cost of about $125 for all 4 actuators.  So I plan to run them to the point of failure to see firstly how long they last, and also to see if there are any weak points in the design.  But TBH, at such a low rebuild cost, if one can achieve 200-300 hours between rebuilds, that's a pretty low per-hour usage cost.  But actual MTBF remains to be seen.

My greatest area of concern at the moment is the rig platform itself.  As I stated earlier, it was never designed to move.  The base is literally a wood 2x4 frame, sandwiched between 3/4" MDF at the areas where the actuators are mounted.  The mounts are bolted through the 2x4, with inserts on both surfaces.  The forces have a tendency to crush the wood, causing some very slight wiggle when pushed and pulled by hand.  A half turn on the bolts gets them tight again, but I can see them eventually destroying the wood to which they are mounted.  This has nothing to do with the actuators, but I can see either some metal plates or an 80/20-style metal frame in my future.

Very impressive. Glad to see you being pragmatic about cost. I too am interested in how durable it all is.

With a project of this magnitude, it's hard not to be pragmatic about cost.  IMHO, the off-the-shelf solutions are aimed at those with vast amounts of expendable income who don't want to be bothered doing any sort of maintenance, or spending any time tinkering.  I.e. they are overengineered and over-built.  I understand the reasons for doing things the way they do, but it places this very cool technology well out of the reach of mere mortals. Cost was absolutely paramount in my design, and I really only threw that ideology to the wind when it came to the controller.  It may or may not ever happen, but part of me really wants to tackle that aspect as well      

[danny_galaga]

Just wow

 

[bobbyb13]

Awesome all around.
Hadn't even considered how some flight games would quaify also.

I'm a composite guy so I automatically start thinking foam and fiberglass for places that would be fragile.

Some Divinycell with the right amout of epoxy/fabric lamination in the right spots would suit well I think (and maybe could be easier than metal?  Certainy lighter.)

If it required some give to keep from stress destruction then regular old woven glass would suffice, but it really would be fun to lay up some ridiculous aramid stuff if it wasn't too stiff for the application.

Really lookng forward to future updates on this.

One of the coolest things I've seen in a while for sure.

[RandyT]

Just wow

 

Your project is way cooler, I only have a couple of feet to the ground if something goes wrong 

I'm a composite guy so I automatically start thinking foam and fiberglass for places that would be fragile.

Composites are definitely cool.  I even considered carbon fiber for the tubes, but I have no first-hand experience with the mechanical properties of these new materials, so I punted and went "old school".  Thin walls, crush strength and rigidity are a plus, and dollar for dollar, you just can't beat steel.  As for the platform, the 80/20 rigs are super rigid and sturdy.  The extra cost is made up by having them be simple to construct.  But there's no denying that they fall way short where appearance is concerned.  Fiberglass (or similar) is far more versatile when one wishes to flex their artistic abilities.

[Howard_Casto]

So what's the weight limit on that bad boy?   I designed my rig so I could mount the whole thing on a u-joint and turn it into a motion rig further down the line but honestly it's pretty damn heavy now.   Not sure if anything could move it plus my fat ass.

[RandyT]

Having not done any controlled testing on a single unit, I'm not sure I can accurately speak to weight capacities.  The rig itself is pretty heavy.  Rough estimate of the current configuration would put the wood/MDF platform at about 50lbs, the metal frame/seat is about 75lbs, subwoofer 30lbs, wheel and pedals 25lbs.  With me sitting in it, the total would be somewhere around 340lbs.  Before I changed things, there was very likely an additional 60lbs on the front of the unit, (50"TV, PS4, chipboard TV mount, amplifier, etc.) and that didn't seem to slow it down any.

I almost think that the 110v power I am currently using, would kick a breaker before the weight would affect the mechanics.  My actuators use internal components similar to units which claim 150kg ratings per actuator, and based on the weight distribution of my setup and what I have seen (felt), I'd say these could get pretty close to that.  My mechanic buddy is a large guy, and I expect he will be over soon to give it try.  I'll know more then  

The thing to keep in mind is that a 4 (or 3) actuator setup in this configuration is carrying the weight of the entire rig.  It's known as a 3DOF system.  There are other 3DOF configurations, which trade heave and limited surge/sway for stronger traction loss, but heave was way more important to me and I can always upgrade to 4 or even 5DOF if I decide to. 

However, if you just want to get a rig in motion, a well-placed universal joint at the point of balance (with the rider seated) will carry most of the weight of the rig, and only requires 2 actuators at the rear to achieve pitch and roll (2DOF).  The actuators don't need to be extremely powerful in this configuration, as they operate in a "push-pull" fashion, with gravity assisting past the center point.  If this is what you had in mind, I don't think you weigh enough to stop it, unless your actuators were very small.  Some (probably smaller) folks have even successfully used modified wiper motors to move this type of rig.

[Titchgamer]

Damn thats cool.....

I can only dream of having the room for something like that

[RandyT]

I can only dream of having the room for something like that

It's not tiny, but it is surprisingly compact.  It's tucked into a corner of my VR room, and due to the odd shape of the room, the area wasn't really usable for that purpose.  All in all, even with the TV stand, computer and servo control "crate", it only occupies about 40 sq. feet. (3.72 sq. meters). Trust me, it was a consideration for me as well! 

[danny_galaga]

Do you have video of it in motion?

[RandyT]

Do you have video of it in motion?

Here's a small clip which I tatered to conserve bandwidth.  Just pretend it's 1995

The system is running the GRID 2 benchmark, which strangely also produces telemetry.  I obviously wouldn't use that view when playing, but it does provide a bit of a comparison between the car and the rig movement.  I could probably tune reaction to be a bit tighter, but even with this level of smoothing, it's enough to be a bit jarring when playing.

BTW, the "thumping" sound is coming from the subwoofer.  The actuators are inaudible when playing.

[Vocalitus]

Wow Randy that looks too cool even for 1995. 

It reminded me of galaxy force 2 but as I recall that was used with motorized wheels.  Could that method help with weight of your super cool rig?

Please keep posting updates.

[RandyT]

Thanks.  The roller wheel approach from those early machines is essentially what the Yaw2 borrowed for it's method of operation.  Great for flying games, but less so for simulating interactions with hard surfaces and suspensions.  Basically, they are only 2 DOF, but can be capable of greater range of movement, sometimes at the cost of speed.  A big advantage of the Sega design is that it is super stable, but at the cost of size and weight.

But the weight of my rig isn't a problem for these actuators (caveat: still untested with a very large individual).  As someone who stupidly tries to adjust the settings for a new game, or worse, roller coaster, while in the seat, I can tell you that the speed and forces they can generate are downright scary (and sometimes painful) when pushed too high.  The height it raises to initially is only half of the available travel.  I really need to try it out with a flight sim to get a feel for how well it does with that genre.  I should probably also make another clip to show the full travel of the rig in each of the three axes.

I wish there was an offshoot called MotionMAME, in order to support those old simulator cabinet games.  Any volunteers?

*edit*  I now see that there were at least 3 different styles of SEGA motion rigs (not counting the 360).  The Afterburner cockpit was large and had only 2DOF, but the GalaxyForce II design seems to be pretty much exactly the same type of unit as the 3DOF YAW2, but with limited Z-Rotation.  The one I remember was Space Harrier, which is without Z-rotation.  That one also seems to use a different motion platform, more akin to the center mounted pivot design.  But I could be wrong.

[Vocalitus]

I was looking at one of those DX rolling Space Barrier cabs but it was too far gone.

Check out this refurbishment thread:

https://pinside.com/pinball/forum/topic/sega-space-harrier-deluxe-moving-cabinet-restoration

It might give you some ideas. 

[RandyT]

Very interesting design.  Definitely a center pivoting design, but with some open linear actuation mechanical components to do the motion.  Those machines probably weigh 1200lbs easy!

That's some amazing restoration work.   

[RandyT]

Finally tried out an arcade game with the joystick feature of the motion control software and thought some of you might find this interesting.

The actuators are running fast and with long travel, so you can certainly hear them now on that wood platform






*edit*  I noticed that the platform is moving opposite from what it should be in the pitch axis, but that's just a checkbox in the software to reverse it and I'm not re-doing the video 

[Vocalitus]

WOW Randy wow.   

When are you going to sell the kits on your site?

[Howard_Casto]

Thanks.  The roller wheel approach from those early machines is essentially what the Yaw2 borrowed for it's method of operation.  Great for flying games, but less so for simulating interactions with hard surfaces and suspensions.  Basically, they are only 2 DOF, but can be capable of greater range of movement, sometimes at the cost of speed.  A big advantage of the Sega design is that it is super stable, but at the cost of size and weight.

But the weight of my rig isn't a problem for these actuators (caveat: still untested with a very large individual).  As someone who stupidly tries to adjust the settings for a new game, or worse, roller coaster, while in the seat, I can tell you that the speed and forces they can generate are downright scary (and sometimes painful) when pushed too high.  The height it raises to initially is only half of the available travel.  I really need to try it out with a flight sim to get a feel for how well it does with that genre.  I should probably also make another clip to show the full travel of the rig in each of the three axes.

I wish there was an offshoot called MotionMAME, in order to support those old simulator cabinet games.  Any volunteers?

*edit*  I now see that there were at least 3 different styles of SEGA motion rigs (not counting the 360).  The Afterburner cockpit was large and had only 2DOF, but the GalaxyForce II design seems to be pretty much exactly the same type of unit as the 3DOF YAW2, but with limited Z-Rotation.  The one I remember was Space Harrier, which is without Z-rotation.  That one also seems to use a different motion platform, more akin to the center mounted pivot design.  But I could be wrong.

There are several more than that.   Software wise they are all extremely similar though.... I had many of them mapped out back in my mame output days.... might still have info somewhere.   I feel like we are getting to the point where a "motion mame"   might actually become practical.   The motion sim rigs get cheaper every day so soon it's not going to be a pie in the sky item.   Between myself and SailorSat we could probably get most of the sega stuff working.   

[RandyT]

When are you going to sell the kits on your site?

I've thought about that, but there are so many parts in one of these, I'm not sure exactly what form such a kit would take.  The best I could come up with would be all of the hardware, the half-dozen or so custom-machined parts (per actuator) and an instruction manual.  Unfortunately, that still leaves some off-the-shelf parts that a user would need to source themselves.  Whether that's marketable is something I have no clue about at the moment.  My gut tells me that current supply chain issues would make that a non-starter, so I probably won't be doing anything in the near term.   

There are several more than that.   Software wise they are all extremely similar though.... I had many of them mapped out back in my mame output days.... might still have info somewhere.   I feel like we are getting to the point where a "motion mame"   might actually become practical.   The motion sim rigs get cheaper every day so soon it's not going to be a pie in the sky item.   Between myself and SailorSat we could probably get most of the sega stuff working.

I'd be interested in knowing what the outputs of those old motion games were based on.  From looking at the video of the actual Space Harrier machine, that title seems to be doing little more than movement taken directly from the joystick (and understandably, a lot less responsively, due to the heft of the machine.)  This is what is being shown in my clip.  The major difference with that title is likely the ability to reset after death and not activating motion until the gameplay begins. 

But I'm sure that there are others which are more complex and there definitely would be an improvement if that data could be acted upon coherently.  It'd be very interesting to develop a plug-in for MAME which could talk to the various motion controllers directly and it doesn't seem that difficult to do, but I have no clue about MAME's plug-in system. 

[Howard_Casto]

Typically  movement for the super scalers mirrors the character's movement and since those games are super simple 90% of the time it will appear to the laymen that the joystick axis is being read, but if you crash/wreck/whatever or hit the bounds of the stage or something that would cause the sprite to move independent of the joystick you'll see some shake.   

For the earlier stuff you had a motor that almost self centered and the game sends a power level of 0 to 15 in positive or negative voltage to the motor to make it lean a certain amount on that axis.   More advanced stuff like rail chase used pistons and such similar to your rig and modern stuff is basically just directx force feedback.   Of course there are a million variations of each kind but like I said, the data is similar at least.