Force Feedback Racing Simulator
I remember when I was younger taking a family trip to Universal Studios Hollywood. While the experience was overall a snore, there was this one ride that really captured my imagination: Back to the Future. For those who don’t know, its a Delorean simulator with a back to the future theme. One of the first rides of its kind it is totally stationary and yet is still immersive enough to give the rough sensation of flight. This ride left a measurable imprint on me during my younger years. For some time I have wanted to make my own, seeing the NASA shuttle simulator and other similar training simulators all over. Well one day while playing mech 4 I realized that I had the power to do so literally in the palm of my hand. So I decided to mod out my simulator. Well a lot of R & D went into this and this is actually a prototype for the main build to come. Regardless its a lot of fun to build and tinker with, and we get to poke a little fun at yet another large demographic.
This project, just by its nature, will be presented a little differently than our other projects. The scale of this project presented some difficulty to properly report using our normal format and delayed us while we made a more flexible framework. So what we have done (Microsoft take note) is take the entire project and broken it down to a bunch of subsystems, and basically produced a mini segment for each section with full documentation and pics and plans. This overview of systems is in essence the master plan.
When we started this project we thought to our self… (Microsoft take note again) “Yah that should be easy, quick and cheap…”. Well, it turns out maybe it’s not as easy as we expected (hooray for scope creep!), Although the prototyping wasn’t so cheap, learning from our mistakes allows us to present you a cheaper way of doing it. When we started we were going to use a Microsoft sidewinder force feedback joystick to produce a 2 axis system. Seriously, what could be cooler than playing Mechwarrior 4 or a flight sim and having that level of simulation? Well turns out this stuff is time consuming, expensive, and no one (that we found) has ever done it on this scale…. so when we started we had to do a lot of testing of different ideas, and methods to achieve our goals. Our first attempt literally tore itself apart and caught fire! I guess we missed a critical update there somewhere….
So we decided to scale our second first shot (we’ll call it beta2) at this to more or less prototype the best way to do it for real… so if a 2 axis system was so easy to do… it must be easier to do a one axis system! Well what good would that be?! Racing sims. Now I am not a big racing sim fan. I am not a car guy in general… in fact I dont know a geek out there that hasn’t mocked the aerodynamic idiocy of a front wheel drive car passing by with one of those huge spoilers on the rear. But the concept of a racing sim really started to become more and more tasty as I started to realize all the fun I could poke at car guy stuff. And ultimately that was the deciding factor.
For starters… you don’t have to be a grease monkey to be able to use tools. Seems that gear heads think that geeks can’t use tools or weld… well “someone” has to build and design the tools to be gear head friendly. This project has some basic raw fabrication of the frames and some of the moving parts that require welding and cutting of steel. It’s not hard work… it’s actually a lot of fun if you have the right tools. We used some nice welders and steel cutting band saws, but you can use a $14.99 jigsaw from your local S-Mart and a steel cutting blade to cut the materials, use it, and return it back if you need to. They take anything back. Or the more ethical thing to do is get a friend to do the welding for you. (Inventgeek does not condone the buying, using and returning of crap to S-Mart or other mass distributors of near worthless junk. )
The heart of the beast. Too much power and it violently tears itself apart. Too little and it’s like a 25 cent underpowered ride in front of the local grocery store. This was the trickiest system to do. Not due to complexity, but more doing it on a moderate budget. We tried linear actuators, and hydraulics and even high end high torque motors for wheelchairs. All had major draw backs, cost and speed being the most common. But we finally found a well rounded solution using a modified winch for an ATV. (The utility type… not your wife on a bad day.)
The Platform Assembly:
The platform assembly is where the majority of the systems are actually located and the user interacts with those systems. After some careful thought and consideration for dimensions and the amount of space we had to work with we were able to accommodate space for all the goals of the project on the deck of the platform assembly. The platform assembly its self doesn’t consist of more than a steel frame, a few boards, some automotive carpet and a good racing chair. But if not built right it would be heavy or not strong enough to support the forces that it would have on it. Also some planning and consideration to allow this to be adjustable as possible so more than just the builder can use it comfortably
Steering Wheel Mods and Mounting System:
The brains of the entire mod. We chose to use a Logitech Momo steering wheel for many reasons. Its performance and capabilities are unmatched for starters. And its built very well. But after some research we were able to find a comparison review of several racing wheels on tomshardware.com. In the review they tore a bunch of wheels apart. This gave us the ability to pick and choose features and to see the internals long before we had to choose. So in the end we found the electronics, the ability of right or left handed shifter and duality of internal controls for the gear shifter, and the interface to the internal motor was ideal for what we wanted to accomplish from the hardware standpoint. But the real kicker is the ability in the configuration software to adjust the force output upwards to 110% of normal. This allowed for a recover in signal loss from the mods. This wheel worked out so well it was like it was built for it.
The gear shifter and control panel:
One of the main factors for choosing the momo racing wheel was the electronic setup for the gear shifter. We had 2 sets of all the controls thus allowing us to relocate one entire set to a more ergonomic layout. While I was at it I decided to go to AutoZone for some parts for this project and I couldn’t help myself… I found a really great bling-a-rific shifter knob that had LEDs in it and light up all bling bling like… so I modified the shifter internals a little to allow for the new knob to be installed and presto! Instant….. Shifter with lights in it. I hear its really popular on the other side of the tracks. While we were there we also picked up some switches for the entire system. (Once again with bling in mind)
The gas and brake pedals:
While some of the mods for this system are really basic it really adds alot to the entire experience. Not to mention it let us use more of those high performance auto parts from S-Mart that seem to be so popular in the local racing circuits. You know like the single use plastic spinning hubcaps! Some are cosmetic, some are functional. And in the true car culture attitude… most are totally unnecessary. But the proper placement of the gas and brake pedals makes those 100 lap races more “endurable”
Every good simulator should have a great sound system. So our kinda good simulator should have a kinda good sound system then as well. After some trial and error we found the best way to set up the sound system for optimal immersion on a budget. We used just a basic creative 5.1 sound system, and with some careful placement of speakers we actually got some good results. And it puts enough bass out to rumble your guts just like that 4 cylinder with turbo and the stovepipe sized exhaust system that the neighbors all laugh at.
So with all the attention to creating motion, and sound we found the 19″ monitor we were using during the testing phase to be a bit on the anemic side. So we used a prior project that we did and slightly adapted it to fit this project. The poor man’s LCD projector was a great fit. Nothing quite like playing your favorite game on a 100″ screen. I will admit it was cool enough to really get me hooked on the Need for Speed Underground game. (For about 15 min, then my Attention Deficit Disorder set in like wild fire on nitrous.)
Final review and assembly:
In this section we basically make sure all the needed extras are there and that we haven’t overlooked anything important. There was alot of stuff we actually had overlooked and had to address before we proceeded to live tests. Like a cup holder! The last thing I want to do is getting locked into a 100 lap NASCAR race without my Mt. Dew… I would fall asleep at the wheel and slam into the wall and flip several times sending jagged flaming bits and piece of the car into the crowds! And we just can’t have that regardless of the TV ratings. (Unless I turn off vehicle damage)
Tools that we used ( I.E. you may want to use as well ) One note on power tools: use them at your own risk. Be sure to read and understand any and all documentation on the tools you use. No amount of documentation can make up for experience. Regardless, there are many people with serious eye injuries at the school of hard knocks. If you don’t know what you’re doing, don’t do it and find some one that can help.
When working with metal be very careful. Metal chips, welding sparks or metal fillings in the eye or slivers in the skin have been known to cause moderate discomfort in some people in the state of California. Many times you usually can’t have a MRI for months after playing with steel in any really significant way. Also, getting through security at airports could result in unwelcome searches.
For this project the main structure of the base And platform is constructed from 16GA(.063)Square Tube. Its important when selecting steel that it be straight and consistent in tone and appearance. Steel always surprises me when it comes to costs. We recently received roughly 400 feet of 20 foot lengths of square tubing, delivered for about 189.00. Sheet metal, however, can often cost much more for a similar weight in materials. The only real tip here is don’t accept materials that are obviously rusted and weathered if it can be helped. We all saw what happened to the tin man when he was left out in the rain…. spontaneous human in a stupid costume combustion!
Cutting the steel:
When it comes to cutting steel, and making nice square projects without alot of fill welding it really helps to have the right tools. Luckily we have access to a nice gravity fed band saw. Now while a cheap Jig saw from S-mart or Mega-lo-mart would suffice, there is much more precision with a unit like this. I have been able to find some basic models from about $200.00. Well worth the cost if you plan on much fabrication work. Especially when you are able to cut 4 pieces all the same length at the same time. Just don’t sit in or walk bare foot on the pile of filings it makes….
When it comes to welders there are several options out there. Stick welders start at about $100.00 for a basic light duty unit. For about $200.00 you can get a basic entry level flux core mig welder. The preferred option is the mig welder. Mig welders are wire fed and alot easier for those just learning. Although if you want to do high power experiments like making buckyballs and doing some basic welding then a basic stick welder may be a better choice. Whatever method you choose, always use a nice welding helmet the appropriate shade for the work you are doing.
The Base Fabrication:
Fabrication of the base is really straight forward. Simply weld the base box, followed by the uprights, and finally the cross bracing. It’s really important that the welds holding each piece together are strong and well bonded, else you end up with a project looking alot like some incremental Linux kernel builds when they break.
2 X 50″
3 X 28″
2 X 50″
1 X 48″
2 X 36″
4 X 12″
4 X 14″ (45 degree cuts)
The Motion System:
After a lot of trial and error to find the right way of making the motion system both responsive enough but cheap enough we finally chose this solution. After the raw fabrication is finished paint it not only for looks, but to prevent rust and corrosion. We found a nice epoxy paint at the good old Home Depot (maybe I don’t go there enough but I don’t have much to make fun of). Epoxy paint can take a long time to dry to make sure its totally cured before you work with it. Also one benefit of the epoxy paint is if you weld this yourself, and its your first welding project, you can hide your welding ‘talent’ under a good layer of paint.
The drive system’s heart:
After trying four other completely different motion systems we chose to modify a standard automotive winch from harborfreight.com (get the extended warranty, and keep the parts). This motor is very high torque, and we only need a max of 15 Degrees of off set in either direction for this project. At about $50 it was way below the next option in price, and with some basic modifications it fit our needs perfectly.
Bearings and pulleys:
For the actual transfer of power from the modified winch motor to the platform we will be using some garage door pulleys. These are really built strongly and are very inexpensive at 10.00 each. We will weld on of the bearings so it wont spin any more and mount it to the winch. A trip to AutoZone, Pep Boys or Home Depot and a 10.00 belt and we are in business.
Next up is modifying the winch. Basically we don’t want any of the mounting bracket, cable, hook, or reel. There are 2 hex bolts on the bottom that will need to be removed to realize it when it is taken apart a small shaft will come out with the reel, save this and set aside. Also there is a lot of heavy grease. Usually there lithium grease in this type of unit so be cautious with it.
With the mounting bracket removed we can see the winch motor and gear house are self contained. There are a set of spider gears inside the motor that interact with a gear on the end of the cable reel. This can be removed with a simple screwdriver and bolted to the new pulley on our project. Now just a heads up here, the housing to this is cast, not machined. So if you drop it or hit it too hard in this process its possible to crack or break the housing. This would be bad as cast metals are extremely difficult to weld.
Looking at the bottom of the winch motor we can see the 2 bracket mounting points the old reel and mounting plate were mounted to. We will be using these to mount the motor to the base of the force feedback platform.
With the new pulley attached, use a standard 1/2 inch bolt about 1 3/4 inches long to mount the pulley to the motor. I recommend using an impact wrench to secure it as the motor spins a bit making it hard to get it real secure. Additionally I took and welded the pulley to the barring and the barring to the bolt to make sure things wouldn’t come undone after assembly was complete.
Next up, mount the assembled motor to the frame in the space under the supporting brace. Use some good high quality bolts if you have access to them to make sure it stays good and secured to the frame. One thing as a hint here is use some washers as shims between the frame and the motor so that you can make sure you get a good proper fit on the belt to the other pulley.
To complete the main part of the motion system we will be building out the upper bearing assembly. This is really easy and straightforward. Just weld a 2 foot piece of the 1X1 that we have been using to the top half of the bearing. This cross piece is what the upper platform will be resting on. Secure the upper platform to this piece with 2 bolts. Attach the bearing (spinning freely) to the upper portion of the base. One in front and one in back with a good long bolt, taking care not to overtighten it.
With everything attached add the belt and check for snugness in the belt. If you can grab hold of the mounting arm up top and force it to slide you need to get a smaller belt or remove some shims. You should be able to put a fair amount of weight on this with out it budging. Like one’s body weight. The last thing you would want is the belt slipping in use. I know this is a crappy pic, but the belt is there if you look hard enough.
Mount an upper platform bearing system in the front of the simulator as well. Alternatively, up front you could use a flanged bearing and a bolt as an axel to make it lower profile and sleeker looking.
Place the platform onto the support arm on the base and attach with a couple bolts. The belt will be on the inside of the platform so if you want to make a guard for this you may. Or not, if you are into the whole school of hard knocks thing.