fast and accurate motion sim, AC or DC ?, which controller and h-bridge

Hi,
I'm Martin form Germany and I want to build a motion rig. I really like this forum and what some users have done here. I read the forum for some time now but it's hard to find the infos I need and to make the decisions of what fits best for me and maybe I have to big demands?
This is my gaming gear so far:


I play racing simulators (simbin games and Assetto Corsa) most of the time and I would like a fast and accurate movement. Even vibrations should be delivered by the motor or actuator, if possible? I read that the scn5 is very good in this but not the strongest and to expensive for me. I want 2 dof with 2 Motors and the whole platform to move, not only the seat.

I still couldn't find out wether AC or DC is better for this.
I read much about DC:
- JRK, Arduino, AMC 1.6. Which is the fastest of them?
- I read that even h-bridges can be slower or faster? Which one has a good price/performance? The DHMsb seems not to be a good diy-choice anymore?
- I couldn't find much about motors besides wipers. Some used the ZYT90, what else is good? Does the motor also influence the accuracy? Maybe brushless or stepper motors could be interesting but to expensive?

I couldn't find much about AC. What solution would be good there?
I thought about using a cheap China-ballscrew but I'm not sure about it.

I don't have much money but do have a lathe, can weld and have some knowledge of ecletronics and soldering, so diy solutions are welcome.

I know these are many questions but maybe somebody can answer some of them?

Hello Marty. Nice setup you have there, do you have pics of that on insidesimracing.tv ? It looks familiar.
AC motors are too slow for race that that ends that. People have use AC motors, but you can see from videos they just are not fast enough.
They connect at the shaft and I have yet to see a motor faster than 30-40 rpm. You could speed it up with a gearbox.
You need to be very careful with 240v motors for obvious reasons.
We have achieved great performance from 12v motors and they are safer and cheaper.
DC motors are a lot quicker and give you that snappy motion needed for race.
Wipers are just not strong enough in the long term , the gearing chews out from constant thrashing.
The best choice of motor is the Australian Motion Dynamics Motors
http://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html they are tough and reliable. Screens MUST NOT be attached to moving frame.
The ZYT90 will also work and do a full frame, but screens MUST NOT be part of moving frame, for overall weight reasons. Motors connected at the rear at the shoulders is the best option for overall weight shifting.
If you are a larger person like one of our members, 12v boat winch motors are better as well for throwing weight around.
The ball screw idea is good and again, a few of us are looking into that, but having a lack of time and access to machinery makes it difficult. Hence currently staying with DC motors.
The JRK is the simplest hands down and performs the best. JRK is 12bit resolution, Ard is 8 bit, AMC is a piece of crap - avoid it completely.
No code to write for JRK, set PID, motor power , feedback and off you go.
Matching h-bridges to control boards like Ard can be tricky with wiring and code writing. JRK has controller and h-bridge in one, use one per motor.
Does that help?

I agree with bsft. JRK's and big DC motors are definitely your best bet. I've done a lot of research and there is no better motor controller available.

The Australian motors bsft linked to are great but depending on where you are the shipping could be very expensive. ZYT90 are also good, if you can get hold of them. I'm trying to source some currently but am having difficulty.

Thank you for your answers, they are helping very much.
Maybe I posted a similar picture on insidesimracing.tv but I'm not very active there.
I will go with DC then.
The JRK is very expensive, expecially if I think about adding tracktion loss. What is so bad with AMC? It seems, it has 10bit resolution.
I have an education in informatics. Programming and adjusting settings shouldn't be a problem, so that might save me some money?
The SimAxe controller also seems to be interesting.
Shipping from Australia indeed isn't good. I will search something like the zyt90.

A ballscrew would make an AC motor even slower, so a higher reving motor should be better?!

AMC you have to build yourself, code doesnt work properly, good luck if you want to build it. There is not much support for it here.
JRK is $99 US, expensive to maybe a piece by piece option of building working out code, errors, finding the right h-bridge, re-working code and pin out setup may be cheaper but....do I go on?
Different options pre-built like the Arduino and simaxe are being investigated, but it is taking time to get codes right.
For race you need at least 200mm per second travel, either calculated on a linear movement with a suitable length arm or the speed of an actuator.
240v motors would need to be geared up to go faster. And as said, you need to be careful with 240v.
Why the keen interest in 240v?
There are reasons most of us are not using them, safety is one, cost is the next.
Ball screw you need a fast motor on the end of it and the pitch of the screw would need to be 10-15mm minimum, even with a 3500 rpm motor and a 1:1 drive.
The zyt90 is a good motor with a 25:1 gearbox.
What sort of frame did you have in mind? seat mover? full frame? We can suggest a zillion different motor/controller configurations, but until you figure out what frame you would like to have, its a bit hard to say whats the better option.
Cheers.

Ok yes you are correct @mad_marty, the info is a little hard to find because there is so many different ways you can build and wire a sim, so we normally wait for people to ask and go I want this , now how do I do it.
Ok looks like @SimonUK has seen the light, for 12v operation and simplicity of setting up and using you can not beat the Jrk. Actually for precision motor control in 12v , Prilads Ard codes comes the closest to be acceptable, not an equal. Most of the Ard codes are not PID controllers like the JRK12V12. Which is a true PID controller. You get what you pay for with Pololu, but do wish they would drop the price back to $65, which was the price I was paying for them in 2009 when I discovered they could be used in a motion simulator.
Previously I build an AMC1.6 with his h Bridge, motion I could never get nice, motors never hit their top speeds and there seemed to be a little lag(delay), plus the H Bridge continually blew mosfets, I love the DIY side of sims but that experience almost turned me off sims totally.
Now the Ard is showing to be a runner but until someone lifts the game and create a true pid controller that can match the speed and reliability of the Jrk I will only recommend them for Dashboard use.
@SimonUK, I have a UK mate who managed to get equivalent motors in the UK. I will question him for a link, when I hopefully race him in Dirt3 tonight.

So @mad_marty my first question, what do you want from a sim. As in motion and setup, me I falling back in love with my seatmover, dont have to worry about heavy drivers, heavy moniters and the speed resulting in motion is almost teeth rattling. So what do you want your sim to do.
Then we can advise properly on what we recommend, listen to everybody and make your decision. We all are a little different.

I will take the DC route.
This is what I have in mind:

A accurate center of gravity with a high placed pivot, so the neccessary forces are as low as possible and the possibilty to change between moving seat and moving the whole platform.
At the beginning I will start with a simple design. Maybe I will try the ballscrew later.

To bad that there are no comparable solutions to the JRK. I'm not sure if I want to spend that much on the controllers.

A lot of us use Arduinos and are perfectly happy with them. Start out with the cheaper option and move up later if you feel that you need to.

Motors under the seat mover will work OK as long as you are not too heavy, like under 90kg and the seat is not too heavy. I've done this sort of frame with seat mover and full frame. As for cost ,yes the arduino and bridges are cheaper but more fiddling needed.
Jrks cost a bit more and if you are that fussy with cost , go price he rest of it cheaper.
Call me nasty, but these days ,time is precious.

I think the frame, the wheel and me will be between 90 and 100kg. The Motors will be 300mm away from the pivot-point.
A qustioen that comes to my mind is, can a brushed motor resolve fine vibration of e.g. 10Hz or more? I guess it might be to sluggish?
I will start with the frame and decide what controller I chosse, if it's done.

@Historiker:
I don't think that Adruino is bad but faster is better, especially in sim racing, where you want to feel every tiny movement of the cars chassis. I'm just not sure if I want to spend so much money for it.

300mm from pivot is a bit snug but it does work. If you can put the motors at the front and raise the connection to the frame higher up, you will get better results because you are going higher over the centre of gravity.
The DC motors I suggested, and yes they cost a bit to get from AU are comparable in motion to an SCN5, in regards to speed, they are faster and they vibrate very well. But thats uses a JRK, sorry.
You can try a brusheless motor if you like. You may have to buy some, set them up and actually test it.
I had doubts about the big worm gear motors after moving forward from car wipers and now heaps of people use the bigger motors, most with great success.
@eaorobbie can back me up on this as he runs the big worm gear motors.
If you are trying to find dbox style vibration, either pay heaps for dbox or use a bass shaker or two.
A friend of mine has a 2DOF dbox and has played on my frames and admits the dc motors provide more nasty jolts and throw, but not as fine vibration as a dbox. But he suggested to me to fit a few bass shakers to overcome this.

I think it isn't that important how high the connection over the centre of gravity is? Isn't the only important thing, how far away the connection is from the cg and that the force is applied in 90° angle (tangentiale to the moving-cirlce)? I would have guessed that the only reason for the frex design is that the platform would be much higher if they placed the long scn-actuators e.g. under the foot-section.
Shakers are a good idea. I already thought about adding them someday.
I will search for some compareable DC Motors being sold in Europe. I read that worm gears eat relative much energy compared to e.g. spur gears. I guess the problem is that spur gears don't hold the position, which might be cured with some springs?

I have been through 11 different frame designs, from motors under back, under knees, up near knees, mounted at the feet end and also at shoulder mount. With MANY different types of mounting connections to try to balance between centre of gravity and power of motors. As well as mounting from 250mm to 700mm away from pivot.
I am 85 kg and have tested many of my designs with 110kg. I know what works and how it runs.
Forget the springs, if you need them, you have designed the balance, centre of gravity and the frame wrong.
Yes big worm gears use plenty of power, mine run at 13.8v at average 30 amps current with spikes up to 40 amps.
So what? do you want a motion sim or are you trying to be a "greenie". Motion sims can suck power, if you dont like power usage, dont build one.

Ive got a 32" lcd, a 850watt sim pc, a 13.8v 32 amp psu and car battery to run the motors, speakers, a laptop, power supply for wheel and pedals. Probably close to 1kw power consumption.

It's not about being a greenie, and it shouldn't sound like critics. With energy I meant maybe the motors would be even stronger with a spur gear but that might be nitpicking and overkill. Maybe I want to much doing everything perfect. I'm very happy about the infos you are giving me.
I will order some steel tube now and get started.

Ok you wont get the same feel from a Ard its only a 8bit slow controller, test most of the codes they work but dont compare to a Jrk and yes used the same motors and power supplies and pots on all tests.
Most Ard produce a dynamic speed as in only changes the PWM with no braking or spike cleaning, result to me is the same we had on the old software with K8055. Hence I only Jrk's they are worth every penny and more.

Keeping you pivot high is a good thing, well pointed out.
As @bsft has said motor underneath requires alot of amps to be used , not the optium position for them, will work ok as a seat mover but as soon as you add the wheel and pedals you cg has moved forwards and you pivot is now behind the cg point of the rig, bad loads the motors up badly, as in now is front heavy, placing springs on will only defeat and absorb tons of the motion cue, please dont go there.

I will do the cg fine-tuning in moving the seat and the sliding front-part, more to the front or the back. I'm not sure which kind of motion I will like better, the whole frame moving or just the seat.
Maybe I will move the motors 400mm away from the pivot but I wanted to keep it small.
As I wrote, I will decide which controller I use when everything else is done. I'm still curious how the simaxe develops and there are also developments on the x-sim.de forum

A really can't find any zyt90 motors. Are they sold out? It's even hard to find similar motors in this price range with reasonable shipping cost to germany.

Ah my worry has gone, you are thinking the right way @mad_marty, as with the motors not being in a prime position the balance will become cridical when trying to get a nice range of movement.
On the motors side ebay might be a good place to look.
SimAxe is being looked into by a few of us now, not much to report yet, looking for finer motor control myself, but I have been spoilt using Jrks12v12's.
@bsft is good at keeping them compact, I got the room to use so I don't worry about size, most of my sims have to be taken to bits to move them around.(Doesn't happen much, lol), his best to comment on that situation.

Hi @mad_marty

I bought these motors for a reasonable price and freight cost: http://www.ebay.com/itm/350562471977

Exactly those are sold out but I think there are similar ones available too.

Thank you. I'm not sure about which motor I want to choose. At the moment I'm thinking of building a ball screw actuator with 5mm pitch which would need a straight dc motor with around 2500 rpm @12V. In generall, there seems to be a small choice in DC motors. At 24V it would be less difficult but then I couldn't use the jrk.

ball screw would work, but not sure if a 2500 rpm motor at 5mm pitch would be fast enough. There has been discussion here about actuators, cannot find the info now .....dammit.
Ok for a 400mm from pivot frame, have a look at this old frame I built nearly 2 years ago with the "other" software. I dont have the frame anymore and the pots were a simple plastic lever on the motor, 8 bit resolution from the JRK.

This uses the big worm gear DC motors. Motors to pivot was about 400mm. Total weight including me was near 95 kg from memory.
If I still had it, the motion would be better if it had multiturns pots and running simtools.