Platform Calculations help needed

Hello
This is my first time writing in the forum. English is not my native language so you will excuse my mistakes. :hi:

I want to built my 3 DoF moving platform which will have the ability to lift 400 Kgs. It will not be any commercial project but i believe that a two seat simulator is better than one seat. The expenses will be double i believe.

I read many topics in the forum but all of them are referring to a one seat motion simulator. Is there anybody building a moving platform and able to help me?

Is there any way to calculate the Hp/ Amps of the servo motors that i have to use?
Can i find electric actuators with this lifting ability?
AC or DC motors? Unipolar or Bipolar servo motors? I believe that servo motors have better resolution and they maybe better than stepper motors hence more expensive.

Thank you very much
Marios

Hi Raceray

Really thank you very much for your reply and all efforts in calculations. They are really helpful. I do not intent to built a platform with lifting ability of 600Kg but aprox 350-400. I could use your calculations for 400Kgs platform as I need it. I would like to build a 2 seat helicopter platform. I will save weight by choosing light materials and leave some equipment out of the moving platform as much as i can. Please correct me if i am wrong but DC servo motors are more powerful than AC or simple DC motors isn’t it?

I saw the forcedynamic-like 301 simulator but in my opinion is not for helicopter simulator application. Could be a nice military Jet simulator project. Helicopters must fly smoothly

Sirnoname i believe that eclectic servo motors or actuator make cleaner and faster installation but you are right they have better lifting ability. I do not know if hydraulics are faster that eclectic motors?

Thank you for your reply
Marios

Hello
I found a photo of the platform i have in mind to Built.
It appears that the platform in the attached photo has AC servo motors with a reduction gearbox. The rotary motion of the motors changes to linear by the levers.
Does anybody knows what the reduction gearbox is there for? Any estimation of the reduction ratio?
Thank you very much
Marios

Ratio depends on how fast and how mutch force you want. Motors looks like normal AC asyn. motors.

I saw the red boxes and thought that they are servo controllers.
Do you believe that normal AC asyn. motors have enough resolution for simulator application? I know that servo motors are used in CNC machines with great resolution that is why i believe that in a flight simulation platform servo motors are needed. I am not sure anyway.
Mambo if i choose small reduction the force will be greater or it works the opposite?
Thank you very much.

Hi Marios
When a motor get reduced a 100 times(i=100)he gets 100 times stronger and rpm gets 100 times lower
There is allways efficenty loss depending on type of gearbox
Forces given depents on lenght lever arm:1NM=0,1kg on a meter and 10kg on 1 cm.
regards Ad

Yes small red gearbox are for optical sensors but that dont make it servo. You can use AC asyn. motors they are cheaper but they dont have good stall torque and for this aplication you should use better frequvency changer with vector control (you have better torque around 0 RPM ). If you want build something like on pic. i would go to powerfull DC motor like ( http://tncscooters.com/product.php?sku=106180 ) you can use two on one axis ad if you use weight compensation (like they use) you cut the cost really hard. Cost of industrial AC servos with gearbox and driver are really high (if you buy something from china my bet it would be around 2500$ for each axe)

Youre having 400w ac servos with driver for 300,00$ from china and 370,00$ for 750w version
Most expensife are gearboxes ,precision boxes needed.
But i belive they will cost far below 2000,00$
regards.Ad

adgun: Do you have link ?

Hi
I pm it to you.
regards adgun

Hello
Thank you all guys for your interest and help.

So i understand that AC servos or even cheaper, more powerful AC syng motor will do the job we need to isn’t it. Also money saving is a must for DIY people like us.

From what i could understand i must search for 1000Watts AC servo motors or 2500Watts AC syng motors. Choosing the gearbox will be the most difficult part of the project i believe. How do you define precision. On RPM, Backlash, gearset configuration (planetary,worm etc?)

Mambo what do you mean use weight compensation at you reply?

Adgun i would like the link as well. After getting an opinion for what motors i will need i will search in European and Asian market for motors and i will provide some manufacturers links as well.

Thank you very much

AC syn. is not for us (if they get out of syn they will stop so you need have enough power (they are like stepper motors)), AC servos are practically normal AC asyn. motor but better designed for various RPM range and they have better drivers.
You shoult get some budget limit first.
Weight compensation is the central rod on the pic.
You can use :
air cylinder (with pressure tank or use vacum)
hydralulic (connect vessels, presure tank ...)
gas spring
or counter weight

You need this becouse you have heavy cocpit, so you need powerfull motors. If you compensate most of weight, motors can be smaller.

Gearbox: you should use worm, planetary are noisy (well worm isn so quiet either but less noisy), backslah is important (you can hear it in some video on this site, its really noisy clicks when sim change directions) but less backslash=more money (i saw price of bigger precise planetary gearbox and you can buy new car for that price ). Ratio depends what speed you want and overall sim dimension (you can have levers far from center so you can use higher RPM on output of gearbox, but it would be bigger)
Power requirement isnt so easy like Raceray calculate on first page, it would be correct if you move your sim only in Z direction, but you will mainly rotate it so you must use moment of inertia (this very depends on distance of center of gravity from center of rotation and many more things). If you will build cocpit, maybe it would be better do it in 3D CAD soft and you get prety well idea how mutch power you will need (you can also do dynamic simulation).

I'll dont recomend wormgearboxes, planetary are the best to use.
Most efficient, forces are divyded to there planets ,most dynamic.
Wormgears are sliders ,worm and wormwheel wear out because the friction,and create backlash
They also arent made for accelarete, braking,chance direction,they are made for a continious speed
in one direction,ant they have a low eff.
But with the right tooth angle they lock and motor dont need to stall
regards Ad

If you look at datasheets of planet. gearboxes you can se nois level +80 dB and cost for precise (small backlash) is huge. Planet. gearbox also wear out (you cant do perfect tooth). Wormgears can do change direction and speeds, why they shouldnt ? If you dont have the cheapest type wearout isnt somethig what happen soon and if there are some wearout its easy to change worm, with planetary ger. you can do nothing .. Yes they have small effectiveness.
If you dont mind of nois and price planetary is really best way to go.

Hi Mambo you don't get it.
I never whrote you can't reverse them, etc.etc.
I whrote they arn't made fore it.
Doing it :will shorten there life time in a big way
Cone type wormgears are betther for it, they also devyde forces, but very expensife.
Planetary gears have a far longer life time and will be sceaper the long way.
wormwheels wearout to
Regards Ad

High dynamic use from wormgears will blast the grease out between worm and wormwheel
and gives screaping metal to metal.
regards Ad

I know how you mean it, but i dont get why they wearout faster (than if you use it only for one way cont. motion). If you have right material (wormgear from brass and worm from steel) only one component will wearout faster. Wormgearbox are often use for index tabels in cnc machines so they should handle it. And BTW lots of people use worm gears here (wipermotors) and it works so far well (for the price). As i sad, first thing is have budget limit, than we can say what type is more suitable.

http://www.atlantagmbh.de/servowormgearunit.html for example is usable wormgearbox, price would not be small but i think it would be cheaper than planetary gearbox with same parameters.