MRAP Seat Mover - first motion

Hi All, Wanted to share progress on my first simulator. I recently achieved first motion and am very happy. Wouldn't have achieved it without the collective knowledge available via the simulator communities!

I have called it an MRAP (MDF Rope And Pulley) Seat mover.

An early version...


Still quite a bit to go and only finding about 1 to 2hrs a week to work on it.

Here is a quick overview:

• Built almost entirely with MDF Sheets (no metalwork or welding required)
• Seat mover design
• Uses Ropes and Pulleys to transfer motor output to seat movement
• Use the “Big Wormgear” motors available from motiondynamics
• Uses single 360W cheap power supply from China off eBay (sold as LED lighting PSUs)
• Uses H-Bridges from China off eBay (Sold as 43A units, probably more like 20A continuous?)
• Uses Arduino X-PID controller
• Max 125mm linear movement at seat connection point (equivalent to 250mm linear actuator at shoulder height)
• Max 300mm/sec linear speed at seat connection point (equivalent to 600mm/sec linear actuator at shoulder height)
• By adjusting drive and feedback pulley sizes can change speed and max movement
• Drive and Feedback pulleys also made of MDF using hole saw
• Have currently backed off motor power to 80% and restricted movement to 80% travel (via XPID software)
• Motors don’t seem to be stressed at all, H-Bridges run cool enough to hold finger on drivers (Although haven’t run for more than about 5mins at a time so far)
• Electronics neatly housed in the base assembly
• Uses a 1/2in Universal Socket adaptor as the universal joint
• It is solid but heavy!

Still to do:
Add traction loss

• Finish the front end console
• Paint and decals
• Look at reducing the weight
• Learn how to drive properly

I have been taking photos all the way and making notes so plan to provide more details when I have time.

Here is the first draft of the design notes: (Still needs plenty of updates - Let me know if there is a specific area you want details on)

MRAP Seatmover.pdf

A nice looking setup, once all painted and dress will look dam sweet well done.
So will we see any plans on how you have done this and is it running xsim or sim tools.

:clap:

Video please!!

Yes I have been taking plenty of photos and documenting the build as best I can. Will post when there is enough to make sense - but probably before I have completed the doco.

Still being new to everything am finding I am spending quite a bit of time with the software setup. I wouldn't say I have any game running smoothly yet. All seem to crash with errors at some stage during the game. I have been using RBR (probably the most reliable), Dirt3 on steam, Race07 on steam, and F1 2012 disk install. Not sure if it is my specific installs or just running the software wrong? Will get there though!

The hardware seems to work well (a bit too well - I think I have too much movement) and I am modifying the arduino code so I can hopefully run traction control motor through same board.

I am using x-sim software.

Not a very good video but all I have at the moment:

Awesome work!

Well I can offer you a fix for the software side of things mate, shoot a pm to Rene and gain access to Sim Tools the only game we done have a plugin working on is RBR, all others are very stable and work, I personally tested most and actually race with dirt 3 online every Saturday night for up to 3hrs run without any drop outs.

You have a working sim, still to fine tune, so cant see an issue for you joining in the private beta will give us an insight to find out if xpid is sim tools compatible, cant see it not working we have prilads ard firmware working which is simular, not the same.

Sounds interesting, wouldn't mind trying out an alternate. At this stage probably wouldn't be able to do much testing for a couple of weeks though. Can it be installed without breaking other software?

I have done plenty of embedded coding in the past so can adjust firmware as needed, have done windows programming as well but usually find that a much greater learning curve every time look at new tools. I am a (past) engineer not a programmer.

Im a past hardware tech when it was still simple, 486's and Dos was still alive.
Yes can be installed on the same machine and as long as xsim is not running sim tools will too.
But once stepping over you properly wont step back. No need to adjust firmware to use , send the same uso settings in the same was as a uso the difference is in the real easy of setup and profile creation.

For those interested here is how I drive the seat with ropes and pulleys...



I haven't done much tuning of the control loop yet and you can see it is quite under damped creating some ringing.

Here is a different angle...



The main drive pulley is only 40mm diameter - essentially equivalent to a 20mm lever arm setup however without the constraint of only being able to move the seat upto 40mm. This produces minimal load on the motor. The motors run at approx 150rpm, that's 2.5 turns per sec, so the speed of the seat movement is 2.5 * pi * diam = 314mm/s. Given the minimal load on the motor it will run closer to max speed.

Well done, yes correct on the calc side of things, under load simular motors I have reach 150rpm too, and at this speed on a 50mm level acting in only 180 deg of movement but since Im only using 180 deg it will take 0.4 sec to do one rev so half that for a 180 deg movement and we have 0.2 sec to travel (pi*100)/2 = 157mm) from max to min. So in a mm/s equation the speed we see is 1/0.2*157 = 785mm/s. but in real terms because of the way a seat mover moves it really 100mm of lift so in actual linear terms the calculated rate of speed is 1/0.2*100 so we get an average of 500mm/s

As shown above with some more fine tuning your system of pulleys are a briallant idea you will achieve speeds that are equivlant to scn5s and will end with a very nice result, thought you were doing something and I was right, Top idea , mate. Im impressed.

Fantastic job!

Well thanks to eaorobbie for making me aware of the beta software... I have set it up and while I should have been doing other things I just had to keep going back to have another go all through the weekend. :clap: Very happy with the stability and ease of use. Haven't been able to get F1 working yet but Dirt 3 & Race 07 (both steam) work great!

Unfortunately instead of finishing my build I keep playing it. :?

Happens my friend back to the build

thats why my PVC sim is STILL not painted

For anyone interested I have added a draft copy of the design build notes for my sim as an attachment to the first post. The documentation is taking longer than I expected so decided to post the draft so people can point me to where they want more details.

Had friends round this weekend and everyone was keen to have a go! The sim held together well with no signs of stress which was great. I have my third motor and can't wait to get the traction loss setup. I am writing my own 3 motor Arduino PID driver but it is not tuning properly at the moment so is also taking longer than expected. Anyways its all fun - that's why I am building my own (Like most of you I suspect!)

Thanks for the plans, always good to have something like that so people can build their own.
Good to see it held together for a friend test.
Good to see another ard code, more the merrier.
And , yes, understand the never ending building. I will have a seat mover with big motors ready be end of week touch wood (touches head)
Back to your fantastic build! :clap:

As a short cut mate, I would run a second ard, Sim Tools can send data to it as well as the others, well it can handle 6 separate interfaces at once.

Hi RufusDufus,

Outstanding job!
I had a quick read through the accompanying manual. What a professional job!

Congrats!

John

Agree wow, Top Marks for sure +1 :clap:

Fantastic, it will be great to hear a comparison of the different types of sim from someone that has them side by side.

Can't wait for the review!!