2dof - another in da' house ;)

Hello!

My name is Piter. I'm simracer for 5 years now, and as much as racing I like to develope my cockpit. After few years being a member on this forum I build my virtual car and now it's time for the last part - motion system. I decided to go for a 2dof at first. Don't plan any platforms - only moving seat. Maybe later I'll consider 3dof, G seat or even more. For now dont have any experience and room in my flat for that So I hope I could find some help here if I stuck. Of course I will share all my experience during the build and try to make some documentation for the others.

Also please be kind for my mistakes, 'couse English is not my first leanguage.


So for the start I bought:

- Arduino UNO R3 (made in china - was chip and deicided to test its quality)
- Moto Monster Shield (made in china - same thing with quality)
- PSU 12V 57A 700W DELL 7000814 (server PSU) - used


Now I'd like to buy some motors, but here where I live - In Poland it's no so easy. I dont want to pay more then 50 EUR for 1 motor. I've found something like this:

http://www.magmapolska.pl/7716mygz-180w-200w/ about 42 EUR
or
http://www.magmapolska.pl/7712myz-150w-200w-12v-24v/ about 67 EUR (too expensive, but if much better I can consider it)

What do You think? These motors are build little different, but have almost equal parameters:

-12VDC
- 200W
- RPM without load 3600-3750
- RPM with load 2750-3000, after reducion - 180 - 200 RPM
- current with load 24A
- reduction 16.5:1 or 25:1

Could You help me to make a choice?

Ok, that's it for the first post. I'll keep You inform.

Thx noorbeast

I've read about this motor and it's great, but little too expensive for me at the moment. I'd be very greatful if anyone could tell me what he thinks about my first proposal:

torque of both motors at first post is: 0,63 Nm with load and before reduction. Do I have to multiplay 0,63*reduction ratio to get Nm afetr reduction? Is it correct?

Upper link (noorbeast write about) shows as motor with 20Nm.

I proposed:

1 . first motor - little quicker under load and cheaper, but has less torque (180RPM vs 110RPM; 42 vs 67 EUR; 10Nm vs 15,7Nm)
2. second motor - little slower under load, but has more torque and is more expesive.

I'd really like to buy the first one if anyone can tell me it will do.

I will post some pictures as quick as I preapare something.

EDIT: one more thing - just recived an answear from company that sells two motors above. They said second motor is using worm-gear and the first one... hmmm I'dont know the name of it in english but it's something like toothed-gear or cogwheel. I dont know which is better...

Hi!

yes, roughly equal (you would need to know the reduction stage's efficiency as well to multiply the result)

yes, we cannot get high speed and high torque at low cost
but if you want to use the first (weaker) motor, you just have to reduce the lever length accordingly

Thx RacingMat. So today I made a sketch:

http://postimg.org/image/hxm9oonnb/

I need to reduce the lever, but do You mean the lever painted in red on my picture or some other? I don't want to move the seat too much. Only a little, so I imagine this element can be short (does anyone know optimal dimension to start with this part?).

What is more important to have a good feel wit motion rig - speed or power (I know - both, but if You have to choose)? '

First motor is weaker but faster and You say I can reduce the lever to neutralize it. Second motor is slower (but with more power) and maybe this is a problem too? How we can fight with this?

I dont know is it important or no, but my weight is around 75-80 kg.

My picture with number 3 shows what I want to achive. Only place I have to build is under the seat. Sadly I can't use more space around ;(

Thank You for the link with calc, but with all this theory you can have a headache After the lecture I can see there can be quite difference in torque and speed with small changes of the arm lenght. In practise I will start with 8cm and drill some more holes in 4 and 6 cm to check it later if needed.

@gorzasty

first posting image: this forum is wonderfully marvellous to post image, simply drag and drop it onto the message you're writing
and them choose Thumbnail or Full Image
tadaaa !



second: the lever
yes, it's the red one
for example (depending on other parameters) 3cm is short 6 cm is long

third: speed or power
In my opinion, I don't enjoy too much being shaken too much but I prefer precision (no lag with game on PC): I would advice you speed!

Thx again, You are all very helpful. I know with this picture, but the problem is I have less than 10 post here so I cant post links or image because of spam protection.

Today I've got my PSU. It's working, but the noise is terrible. Small fan is almost screaming. If I use it my wife will kill me ;/ So I have to give it back.

Can I use a toroidal transformer instead? Someting like this:





I'd like to buy 230V:12V/600VA - 50A? Little bit more expensive than my PSU, but totally quiet, and it seems to be more reliable.

@gorzasty - There is a Mod for the DELL PSU to stop the fans from screaming when you power them on...
(Essentially you ground the control wires so that the PSU thinks it's gone past "Self test" startup mode)

I will see if I can locate it via the FAQ for you and post back here.....

Here is one from the FAQ

And another from a Google Search - I think this is the model you have:

Archie You made my day! With this knowledge I dont have to return my PSU, and have some more money for better motors. After You put this info I've searched Internet and found topic: http://www.rcgroups.com/forums/showthread.php?t=1750411

Maybe I even try to mount larger Fan (120mm) from the top. It would be quiter.

You are welcome @gorzasty - Saving money is the foundation of DIY

I'm afraid of one of my parts - http://www.ebay.com/itm/310780916584 (Monster Motor Shield).

They say it can stand max 30A max , but for 1 or 2 motors connected?

How do You think - should I buy 1 or 2 Motor Monsters if I bought 2 x 200w motors (http://www.magmapolska.pl/7712myz-150w-200w-12v-24v/ - max current is 24A each)?

I know if I simply multiplay 24A *2 it gives 48A which is too high for 1 MM, but maybe there is not necessary in practise for 2 MM?

@Pit has achieved some good experiments on using a Motomonster (or more) per motor for high current demands... look for his posts

Thx again. Just like I thought... Yesterday I ordered next one MM. Now I have to wait another 2 weeks for it ;/

Today arrived my first motor - whoa! It's big! Bigger that any wiper motor. It suprised me a bit. I also mod my PSU - now it's quiter, but still to noisy IMO.

I put SMC3 v7 code to Arduino and installed SIMTools. Tried LFS, and simulation works. OK, I'm happy about that!

Made some more tests of my motor and tried to connect it directly to my PSU, but it behaved in a strange way. He started to turn, but after a short while he stopped. Sometimes when I help him with my hand he started again and sometimes not. It was very short test and I think the reason was my bad connection between PSU and motor. Maybe the motor stopped turning because of current was too low. We'll see after I connect it through MM.

Tomorrow I'll try to make some pictures.

Sounds like the power supply itself is cutting power, have you done the modification to the supply to let it draw max amps? There is a sense line that needs a load on it otherwise the supply will only let you use limited current.

My first tests:



What is strange - if I put my multimeter in the loop (current mesurement) engine works as it should. If I connect motor directly to PSU it behaves like he had too low current and can't spin. I dont understand. Maybe it's not important at the moment. In a few days I'll make more tests with one motor and one MM.