2DOF Motion Sim by masosi

Hi everyone,
I'm new here and would first of all like to say what a great community this is. There is so much inspiration on this forum!

So much inspiration in fact that I've started my own sim based on a lot of ideas here. Over the next few days (I hope) I will post what I've done so far.

With no real previous desire to have a racing simulator, I decided that I would now like to build one. This project would be a nice combination of software, hardware and electrical which are all of interest to me. It started with getting an idea of prices, and with that I started stocktaking what I had from previous projects and what I had claimed from job site demolitions as an electrician.
This is what I had lying around to start with.


An fibreglass adaptable box from an electrical installation in a hospital. This used to house current limiting fuses before feeding an airconditioning switchboard. The switchboard was upgraded and incorporated the CLF's so this was redundant. It measures approx 600l x 410w x 210h.

The fan is a 120mm 240V AC fan from an decommissioned UPS. This thing really moves a lot of air! The terminal strips are from old switchboards around the place. The brass terminal blocks are neutral and earth bars from domestic switchboards. The Estop button was from Jaycar I think.


Another bonus was having two unused 28" LED TV's that were to be installed on a job. Right place at the right time I guess. These will be 2 out of 3 screens for the best visual experience. I just need one more of the same model and it will look slick.

More to come...

masosi.

Hey @masosi welcome to this forum and good luck with your project!
Will it be a seat mover or a full frame? 2DOF? Arduino or JRKs?

Hi @masosi
Welcome and good luck with your project

Nice size screens there will look awesome on triple head

After going looking through other a few other peoples' builds, I decided to go with the proven 12V 200W motors with worm drive gearboxes from Motion Dynamics. 12V suits a lot more controllers out there, not to mention 12V power supplies are more common too. I almost went with the 24V version, then realised the motor controllers I wanted to use were only good for 16V... But that's later on.

I have a video of the power supply I'm using but I can't upload it at the moment on hotel wireless internet that drops out every 10 minutes. I'm in Cairns at the moment. It's a server power supply from a Dell PowerEdge R900 and it's quite impressive with its 1570W output (130A or so @ 12V). I'll post more details with the video. It was the first thing I bought because nothing I had lying around would be big enough for the instantaneous current draw of these two motors. I paid $53 delivered from eBay.

So this is a pic of everything I had at this point. You can see the power supply there with the mods I've done to it.


Oh and the speakers! Just a set of Logitech 5.1 speakers from Gumtree (a local trading website like the trading post) for $50 in brand new condition. The computer will take care of the surround sound part. They don't have their own decoder but thats fine!


Big day tomorrow, gotta sleep!

masosi.

The plan was to make something along the lines of what @Erwan960 has done here (http://www.xsimulator.net/community/threads/diy-2dof-simulator.4793/).

I like the idea of the JRK motor controllers. I do a fair bit of embedded electronics design and prototyping, but the JRK looks like a well engineered bit of kit with the software and the reputation to back it up. So I went with two 12v12 controllers from RobotGear here in Australia. There is something like a 3 week wait though... Anyway, they have been ordered.

While looking for a Logitech G27 steering wheel and pedals on Gumtree, I came across this for sale on the other side of Brisbane. A welded steel frame with the racing seat and G25 steering wheel, shifter and pedals. This was a big leap foward - it saves be a weekend of learning to weld!


While I was out, I stopped in at the wreckers and picked up a Commodore tail shaft for $50. As luck would have it, they scrapped a entire skip bin of damaged universal joints the Friday before I went there... oh well.


This is really all I need. I'll cut out the universal joint and the end flanges and weld them back together to make a shorter version - about 300mm long overall.


masosi

Nice progress

I started work on the electrical side of things hoping the JRKs would arrive soon...

I was thinking this would just be an enclosure to house the power supply, a fan and the JRKs, but looking around what I had in my shed, it soon started to get a bit out of control... I decided build a button start, button stop, Emergency stop type of setup. The idea was to reset the E-Stop, press the start button and have the fans start, the 12V power supply start up, then the computer, screens, and steering wheel. The E-Stop would only shutdown the 12V rail, stopping the motors from getting out of control without shutting down the computer and screens (for debugging obviously). Then the stop button would kill all power to the sim (after the computer had shutdown).

So lets start.

The adaptable box I mentioned earlier already had some holes in it so I made use of these and started with turning a 25mm hole into a hole for the IEC lead. This fibreglass is so easy to work with - just filed it out to make it fit. I marked out the fan with a template and cut it with a jigsaw, drilled 4 holes and its in.

I had a decommissioned duress panel from a medical center which had 6x 24V DC relays, indicator lamps and terminal strips. Here is a photo after I butchered it for parts.


I started to lay things out to see what would fit. The little black box is just a 24V dc switchmode power supply for the control wiring. And that is the Dell power supply - I'll get back to that.


A bit of DIN rail, 10A HRC fuse, 3 relays and terminals to suit.


Starting the control wiring.


Getting there.

Cut out some holes for power points.


Some second-hand power points - its amazing what they throw out...




Done for now.


All the usual stuff... This isn't necessary - I only did this because I had the stuff lying around and its the only part of my job that I enjoy and I don't get to do enough of it at work. Blah blah, this stuff will kill you if you are clueless blah blah.

So the Dell power supply goes in that blank space there, then the backing board for the enclosure sits over the top of all the 240V stuff on M6 threaded rod stand-offs. Only the positive and negative 12V cables come up to the top level - so its pretty safe when working on the JRKs etc.
Like this:


And this is where it sits at the moment - work has been taking up any of my spare time recently. But there is more to come... I plan to have those black and reds feed directly into the JRK's and out to the motors, with shielded 2pair cables going off to the position sensors, and shielded USB cables going to a USB hub which go to control the JRKs. It will make sense soon.

masosi.

Hello dude, nice job in getting the equipment,
Id suggest you mount the motor connections as high as possible in the photo and as far as possible forward , like more towards the feet end. (I couldnt draw that far in the photo).
Dont make the lever too long as they are 25:1 boxes, so 45mm CTC max length would do.

Well @bsft, this was my next step.

I used a cable drum and some timber to elevate the steel frame to find the center of gravity while sitting on it. I made a timber frame first with scrap timber and some ply I had lying around. This thing is not going to be very portable like some sims around here!





I got these brackets from Bunnings to mount the motors. It would be too lucky to have the holes in the correct positions, so I just used one hole and drilled the other.


A couple of M6 nuts and bolts and they are free standing, ready to be bolted to the timber frame in place.



This is where I'm thinking of putting the motors. A bit of maths went into this, I'll explain shortly.



And that is one of my dogs, she's not impressed because it's about 35 degrees and humid...

masosi

Yep, thats more like it. Can you sit the frame lower though and will it fit in between motors? The lower it is the better.
Also , Id suggest connecting the motor like in the pic

I bought some 1/4" threaded rod with nuts to suit. I had some flat bar lying around to use as levers off the shaft. These holes are 45mm apart which is spot on with @bsft's suggestion!

So, the 45mm lever rotating 120 degrees provides 78mm of vertical travel. I was planning to attach pushrods with heim joints to the steel frame 760mm from the fulcrum which gives me about 6 degree of travel. This works out to be 100mm travel at the furthermost point from the fulcrum.

I think this will be enough travel, i don't think cars travel much more than this in real life.

What are your thoughts, i don't particularly want to lower the steel frame but i can raise the motors?

Depends if the frame hits the front on the bottom or not. If it leaves a bit of a gap, then thats fine.
From experience, you may want to use 120 deg angle , but if the frame can sit lower, it will be an advantage.
My old foot motor used about 120 deg angle as well, and it had about 20mm clearance from hitting bottom under motion at the front.
Lower the frame, again will it fit in between motors or not?

The steel frame will be 300mm above the timber platform, with the steel frame traveling up 50mm and down 50mm (100mm total). So it won't go anywhere near the timber base. I did this to make it easier to get in and out of the seat.

As it is now, the timber base is only just wider than the steel frame, so the motors wouldn't fit on the outside, but could easily fit inside. In your experience @bsft, is 6 degrees total travel enough for a realistic experience? If I need more travel, I can move the pushrods towards the fulcrum.

masosi

6 deg is fine, a good profile will make it feel like more. My old foot motor was something like that.
Id really suggest you make a wider base, move the motors out wider and lower the frame. If you are really worried about hitting the bottom, put a lump of rubber under it.
Overall, up to you.
Dont put motors inside.

The heim joints and the position sensors have arrived - still no JRKs though
The heim joints are from eBay for $20 for 4 of them delivered. The were meant to be M8 but are more like 5/16 (I think thats right). M8 just doesn't fit in either end. These will go from the 45mm lever up to the steel frame.

The position sensors are from element14, they are manufacturer no 6127V1A180L.5. They are 180 deg sensing with 0-5V output.

@bsft Ok will do thanks. Lucky I havn't cut and welded the universal joint yet - it will be tight but I think it will work. I will probably be able to get 200mm long instead of 300. I can make another base. I didn't think it would really matter having the motors on the inside compared to the outside? But that's why I'm here!

masosi

Here is some dodgy maths to show what I was going to do. I'll change the 310 height to 200 (I hope).

Ignore the calculations up the top to do with the level travel - I changed my calcs to only look at the vertical travel, which is what I mentioned earlier.

Screen Stands

This was my original idea to support the three screens.

I know, my artistic skills are amazing - not.

But... this is what I did end up with...


The two stands are for PA speakers, I got them off Gumtree for $40 and they support about 50kg each. They are Hercules brand. A mate then suggested using aluminum duct we use at work and I had a length of this lying around.





I laid out the screen to get measurements and realised this wouldn't work very well. I drew it up in CAD instead, that way I could work out the angles and measurements visually.
I decided to mount the two side screens 30 degrees to the middle one. I had some ali plate lying around from another project so cut out some angled plates to suit.


This would take care of the top and bottom of each change of direction, but I wasn't sure that it wouldn't twist with the weight of the three screens hanging off the front of it. So instead of cutting the duct all the way through, I just cut the top, bottom and the middle web of the duct.



And then bent it into shape.


Then the plates would line everything up for me.


Too many pictures in this post...

I just used metal tappers to screw the ali together - easy and rough.

Next was to fix this to the speaker stands and as luck would have it, the posts are 36mm diameter and being a sparky, I'm never short of 32mm saddles. These worked a treat.


And from the front.


Now the exciting part. Some results!
One screen.


Two screens.


I'm waiting on my third one now. The screens have the 100x100 VESA mounting points on the back so I just used the top two M4 holes through the ducts' middle ridge with washers. They won't be going anywhere fast. And because the weight is on the front and that's the way it 'curves', there is no chance of it falling over. The legs of the speaker stands are fun to trip over though.

This is all I have done to date. Looking at it now, it is nowhere near as elegant as some of the sims I've seen on here - but at this point I have spent about $1000 with pretty good results! So I'm chuffed and cannot wait until the final parts arrive and I get the time to finish it!

I will post again when I have done some more work!
Thanks everyone for the comments so far!

masosi.