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| 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 ;D 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:
--- Quote from: Vocalitus on April 24, 2021, 05:11:50 pm ---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. --- End quote --- 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. --- Quote from: bobbyb13 on April 24, 2021, 05:36:11 pm ---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? --- End quote --- 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. --- Quote from: Zebidee on April 25, 2021, 03:38:17 am ---Very impressive. Glad to see you being pragmatic about cost. I too am interested in how durable it all is. --- End quote --- 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 :) |
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