Racing Sim Design Help Required

Hello All,

Let me start by saying that this site is exactly what I've spent countless hours searching for, thanks.

This is my first attempt at building a simulator so please excuse my ignorance.
About me:
41yr old dad of 3, two boys and 1 daughter.
Profession: Control Systems Engineer
Skills: Mechanical A+ Electrical A+ PC knowledge A+ Spelling C- :


I am currently researching :les: and considering the possibilities. I will begin to aquire parts very shorlty. Below I will outline the basic concept. All suggestions and feedback are greatly appreciated.

Overall concept:
Serious racing simulator for me and the boys (I always carry everything to extremes)
Platform simulator - totally enclosed.
Steel tubular under-frame with wood sides & top
2 or 3 DOF - Undecided - Suggestions?

PC: (already aquired)
3 22 wide screen LCD monitors controlled via Matrox triple head digital GXM
Geoforce 8600GTS 512mb PCI-E video card
Intel DG33TLM LGA775 Mainboard
Core 2 Duo 2.66Ghz
4GB RAM
Game & motion software on same PC


Controlsalready aquired)
Logitech G25 Steering Wheel, Pedals, & Shifter (off the shelf products for now, will refine later)
Custom USB button setup built into the dash (game functions)

Sound: (already aquired)
Logitech Z-5500 Digital
4 Aura bass shakers
2 100amp subwoofer amps

Electric or pnuematic - still undecided - leaning towards electric but open to either option.
Interface? Suggestions / Opinions Please - Preferably USB
I would refer to buy a prebuilt interface rather than a DIY

At this point what I really need help on is deciding electric or pnuematic and interface choices. I have access to wide variety of parts (eletric/pnuematic) so please feel free to suggest as you like.

Once again all suggestions and feedback are greatly appreciated.

Thanks,
Joe

BTW: An idea of how extreme I have a 1500HP drag car that runs the 1/4 mile 7.9@181mph. Powered by a supercharged / aftercooled fuel injected 4.6L DOHC Ford engine :mukkies:

Hi Modsso,

Welcome!

Well, tell me how much you could/want to spend on actuators, and I can tell you how extreme your simulator could be. If you want a rock-solid plaftorm with plenty of power, then you have to go for big gearhead motors like those on http://www.servos.com or hydraulics with proportional valves.
Be aware that standard AC motors are not able to drive bi-directional. Just 3-phase AC motors. Although those 3-phase motors can be driven with single phase power supplies.
For heavy cabine platforms I wouldnt recommend pneumatics, as the masses are not easy to control by air (cause it compresses)

We are trying to use wipermotors currently, because they are really cheap But they are just toys.
If you can afford big gearhead motors, then go on, we'll help you to get them working.

That, and the fact that you have access to plenty of tools is very usefull.
The interface should not worry you. Someone will build one for you, when you have the frame/actuator setup

Regards
Christian

Christian,

Thanks for the reply. With any project $$ are always a concern, but to me it's not the determining factor. I would rather do it once the right way rather than multiple times the wrong way and end up costly more. I figure the platform with driver should weigh no more than 500lbs. At this time I am not going to enclose the simulator so that will help with the weight load. I am leaning towards pneumatics for simplicity and cost. Comments on this cylinder http://www.grainger.com/Grainger/items/4VB50 At 100psi it supports ~300lbs and can generate 1300lbs of thrust. However, I am not opposed to using electric gearmotors. I only have single phase service so three phase stuff is out and I don't want to get into invertors and drives..Etc. There are reversible single-phase 230v/115v ac gearmotors available that can do the job I believe. Something like this possibly? http://www.grainger.com/Grainger/items/1LPX6

I started construction on the platform frame and it is almost complete. It's complete up to the point where I need to decide what kind of actuation to drive the platform so I can locate and make mounting hardware. I'll try to take some pictures tonight maybe. I am having trouble designing in the mechanics for rotation axis (yaw) so I want to go with 3 DOF to start with and keep it simple. I am aiming for something along these lines With my lack of experience I have a several questions where I use gearmotors or pneumatics

1) I aiming for 15-20 degrees of pitch and roll using 10-12 of stroke. Is this adequate?

2) What would be considered a good rate of movement?

3) What interface should I use and where to get one? I'm ready to start the electronics portion now.

4) X-sims capabilities....how many DOFs is it capable of controlling? Is it better (smoother / faster) using pneumatics or gearmotors?

5) If using gearmotors what kind of torque output would be required for this application?

I have more ?s but that's a good start anyway :

I setup the multiple monitors and tried it this past weekend on GTR2......WOW is all I can say.

Thanks, again.

Just imagine. 500lbs in movement-> the valve closes. What will happen? Do you think the 500lbs platform will stop immediatly? No, it does not, because the mass of the platform will continue to move until the air in your cylinder will be compressed enough to brake your platform. And then? Will it rest? No, it will start to move back and forward, until the pressure on both sides is equalised. In other words, your platform will behave like a rodeo bull if you'll use pneumatics.
I can tell you this for sure, as one of our member has experienced this behaviour.
Pneumatics are just suitable for lightwheigt sims like the RnR or similar.
If you want to build a valve operated system, then you should use hydraulics with $$$ proportional valves. Well, you could start with I/O valves like the jwi_de but as you mentioned before, that you want to do it once the right way...

Imho you should go for (worm)gearhead motors, if you want to build a car racing sim platform. But its up to you to decide for yourself

I am new to the AC motors stuff as well. But I can tell you, that only 3-phase AC motors can drive bi-directional. But anyway, you are right as well. It is possible to drive a 3-phase motor by using a frequency inverters with single-phase.
If you are going to use AC motors, you will have to buy a servo controller for each of the motors, which is interfacable with Thanos motion controller.

Or you could use some 1-1,2kW 36-48V DC motors with h-bridges. This would be a far cheaper solution as you would save expensive AC servo controllers, if you are able to build a speed reduction for them (60:1). You could to this with pulleys and engine belts for example.

If you want to prevent those freewheel issus EvanF mentions, you could connect those DC motors to a worm-gearhead instead of the pulleys. You just would have to ensure, that it solid enough, as those wormgears dont like direction reversing that much.

Let's see some pics :happy:

I like that design. Just go on!

Could be a bit more I think. But this is adjustable by the position of the actuators.

I think 0,5-1rps

Profiler1-> 2 axes
Profiler2-> infinite axes
As Sirnoname needs beta testes with working sims to test the Profiler2, please dont hence back to build a 3DOF. The Profiler2 is ready for long time.

That depends on the lenght of your leverages as well.
I'd say above 150Nm at 0,5-1rps. The more the better... By reducing the lever the force can be multiplied to equal parts.
Perhaps you should ask EvanF for some advice, as he has built a similar construction already.

Regards
Christian

Update:

I have been focusing on the cockpit last 2 weeks, about 80% done with the fabrication. Just trying to finalize up things now. I figured I would build this thing in 2 steps, 1 is the racing cockpit and hardware, 2 is the motion simulator and hardware. I have been researching, and have narrowed it done to an electric application. The dilemma is DC vs. AC, both with advantages and disadvantages. I have looked at scooter, wheel chair, winch, and almost every kind of DC motor available. DC will draw significantly more current, motors are weak compared to AC, require batteries, and some sort of charging system - but will cost less. AC on the on the other hand is stronger, more readily available, but will cot more. I am really leaning toward AC. Also, split single-phase motors can be reversed. I thought the one I referenced earlier was split phase, however, it was mechanically reversible only. See http://www.grainger.com/Grainger/items/5U169 for an example of a split phase reversible single-phase motor. The other side is 3-phase, motors are cheaper but require the use of a VSD for this application. VSD can be run from single-phase source and power a 3-phase motor. Down side is you lose 50%, meaning you have to double the VSD size from the motor rated HP. I deal with VSDs on a regular basis; problem is most VSD are meant for speed control and not position control. Position control require very fast ramp rates and higher over current protection and the position control VSD are quite expensive. I have several standard 5HP VSDs laying around the office that I might try experimenting with in the next couple of weeks.

Will try to take a few pics tonight if I can remember.

Hi Modsso

Here is an explanation of how these VSD (or else VFD) controllers work:
http://en.wikipedia.org/wiki/Variable-frequency_drive


I choosen these type of VSD controllers for my big 6DOF platform:
L200-022 NFE
http://www.elektromotorenmarkt.de/elekt ... ctedPage=1

And probably use these wormgear motors as the worm mechanism will allow positioning without the need for VSD to constantly sending pulses under load:
WGR 090-020-100L4
http://www.elektromotorenmarkt.de/elekt ... ctedPage=1

These VSD controllers aren't designed to work as servo controllers (as I seen in the manual) and start to loose their torque when the revolutions of the motor is dropping below 15rpm... That's way I chosen a wormgear motor.

The good about these VSD's is that the input control signals are very similar to the inputs of the DSMhb (dual simple mosfet h-bridge) that I made. One line is voltage filtered PWM signal (0v to 10v) and two lines are direction control signals (+24volts). So, I only need some voltage level converters to adjust the control signals to the proper voltage level to drive them with my AVR motion controller!


Also explored the true AC servo controllers but I found them too hard to control without the need of a dedicated computer. They are just too complex!

Regards, Thanos

I deal with VSDs or VFDs, which ever you prefer, on a daily basis for work. I downloaded the quick setup manual for the Hitachi L200 drive and looked it over. It is a very basic drive and I doubt it will work for you application. It accepts only two types of input signals (0-10vdc & 4-20mA). 0-10vdc is not PWM and will not work as such. To reverse this drive it requires a contact closure between terminals PCS and terminal 1. Another issue is the ramp rate. Drives slowly ramp up to full speed over a given time period, ~60s. On some drives this setting is programable, I did not see this in the quick setup manual. I did not download the full refence manual so I can't be sure. I have a drive on my desk that I think might work. It accpets a -10 to +10 Vdc input signal with -10vdc being full reverse and +10 Vdc being full forward. I believe the issue will be getting it to reverse fast enough. Like I said, the problem is VSDs are meant for speed control and not position control. Standard drives are not meant to be reversed rapidily. There main application is speed control of motors, pumps, fans, etc. There are position control drives available; however, they are a speciality item and are expensive.

I will try to experiment with the drive I have for this application over the next couple of weeks and let you know. My cost on these drives is fairly inexpensive so if it works we are set.

Hi Joe,

Yes, please! If you can test how fast we can reverse an AC motor with simple VSD's I'd be grateful! I'm exploring the use of true AC servo controllers but they seem to need computer interface to control them nor to mention that the motors have to have attached on them 17bit encoders!!!!!

Well, I have overcome the issue of how to convert a speed controller to a position controller long ago! Then I was using a HB-25 motor controller that is actually a speed controller for DC motors with the ability to also control its direction. With the use of PID algorithm and external potentiometers for feedback of the position, I managed to constantly change the speed (with variable ramp) in such way to be zero when it reached the desired position! I don't see any reason why I cannot do the same for the Hitachi L200 drive, except if there is no way to disable it's internal ramping function!

Regards, Thanos

Thanos, no problem, I'll be glad to let you know the results asap. I've decided to start testing using 2 applications and see what works best.

1) First test: .75 HP 230v TEFC AC split phase motor coupled to a 57.5:1 Parallel Shaft gear reducer, final output of 30rpm. Just going to do a simple setup with a reversing switch for forward / reverse control. I'll try to rig something up to measure the torque. 6 arm mounted on the gear reducer to drive the platform. Should provide 12 of travel in 1 second. Main concern is getting the speed and power correct.

2) Second test: 1 HP 3-phase motor - same setup but with a VSD controlling the forward / reverse.