So for those of you that don’t know I’m on the Formula SAE team at RIT (http://www.rit.edu/kgcoe/formula/) and this year I am responsible for the electronics of the car.
Over the years one of the old car chassis’ made it into the living room of the house a lot of us share. Not sure why it was brought here initially, but last year it was stood up on end for our Christmas tree. Well I was bored last night and had the grand idea to turn it into a driving sim. I figure we can use it for “practice” and it’s something to keep me tinkering over the winter when there are lulls in actual race car building. Plus it might get us some design points if I do it right.
Here is the frame I am working with, F14 circa 2006. (numbering scheme: the first car was F1, this year we are building F20)
Last night I started on the steering, after searching the internet I found a description on tearing apart an xbox 360 controller and using that for different inputs. The steering, brakes, and throttle are all on potentiometers in the controller so it makes it super easy to implement them onto the car. A 100k Ohm potentiometer will be used for each one, they are $3.19 at radio shack. The controller was $20 at game stop.
First task was to tear into the controller and see what I am working with. The guys at Gamestop were worried that the controller wouldn’t be recognized by the computer as it is an aftermarket brand, but after downloading the driver from Microsoft it worked great! The only problem with the controller I saw was the most of the buttons were just contact pads on the circuit board. The plan is to solder a lead from each pad to a break out board then go to switches and the pot’s.
Pics from last night/today:
3/4" socket welded to an adapter plate
3/4 hex fits nicely inside a round tube; ‘infinitely’ adjustable steering wheel distance. Nub on the end is for quick release. I had to give back the baller one we usually use (http://www.spatechnique.com/product_pages/page.cfm?cat=8)
Using the rotary table to fit the bearing in the plexiglass.
Welded a plug to the end to clamp the rot-pot to. Had to turn it down to clear the bearing.
Tonight and tomorrow I am working on getting the controller wired to the bread board and finishing up the other pillow block.
I would think it would be a lot easier to buy a racing wheel and adapt to the car. It would suck if you go through all this work and then works like junk. Even something cheap like a momo works pretty good. I have a g25 and that works awesome. Just my 2 cents but keep up the good work looks awesome.
I thought about buying a wheel and going that route for about half of a second. It’s just the wrong thing to do seeing how I am in college for engineering and all that jazz. Plus, it probably would have been more expensive and time consuming to try to retrofit a pre-made wheel. It’s not like I am bolting it to a desk and recliner…
…
The controller taken apart and wires cut to length.
There are 46 individual wires to be soldered. I am sure the buttons share a common ground but I would rather not mess with it just to save a few wires.
Oh yea, before I forget. I’ll be adding some sort of spring mechanism to the steering shaft to provide resistance and self center just like it had a real scrub radius!
You might be better off doing something like this. I think your time would be more wisely spent creating a fsae like course and getting the vehicle dynamics model close. What game/software do you plan to base the actual sim off of?
I can’t see the picture/video at work but that’s exactly what I am going to do except I don’t have a body or any of those bits. lol. Although there is a possibility the body is in the basement at school… It might be worth sending an email or two for a sponsorship of goodies, except it’s going to cost less than $100. All I need is 3 more potentiometers and some buttons. As for software I’m still up in the air over which one. It will definitely have iRacing on it as two guys have subscriptions on it, and maybe some freeware I’ve found as they have the ability to do track modeling. I am going to look at the ones listed in the FSAE thread too. It all boils down to which actually uses accurate tire and physics models.
small update, got the controller wired up to the bread board and tried a button and rot pot out. Iracing recognized the inputs so we are good to go there. For some reason the left bank of the rot-pots on the controller don’t have any voltage so I am going to see if I messed up a trace or something.
I also got one of my 6 computers up and running. Most of them are junk/old/for parts but parts are good too! I wanted to do a fresh OS install but i couldnt get it to read the disc during boot, it worked once but there was a dvd driver error. I tried 3 different dvd drives and none of them worked during boot, they would read a disk when windows was running but nothing happened during boot. Oh well, it has xp on it and is relatively empty. I had a computer I wanted to use but I think I fried it somehow, it had 4 banks of ram this one only has 2. It should be good for now either way.
Once you work out all your breadboarding, get a circuit board made.
They are not that expensive, and it’s another thing you can put on the list of things learned.
I really don’t need a printed or designed circuit board as it is just connecting the buttons and rot pots to the board. I might get a cheap thing from radio shack to use as a ‘connector’ between the controller board and everything else.
---------- Post added at 11:40 AM ---------- Previous post was at 11:37 AM ----------
The APCircuits estimator is helpful during design as you can use the free drill sizes.
There were free programs out there that let you do PCB layouts. I used to use Ultiboard and Ultisim, but lost my HD a few years back, so I lost the install.
---------- Post added at 11:47 AM ---------- Previous post was at 11:40 AM ----------
I also used Advanced for Production grade full solder masked and screened 9 layer boards.
I have not played with their free software, but once you get the basics, its just a matter of adapting
to the tools provided. Like Solidworks vs ProE
pcbexpress.com is also a good one. We use tinycad on the formula team to develop the steering wheel, auto upshift, and traction control boards. Although I think we use the motec traction control module now.
oh, ha. The car was wrapped up in christmas lights and I broke a few moving everything around. The living room never gets traffic except when we have parties so it’s a low priority.
