SERVOs

@bsft, ok i have the estimation person up to 100 kg , high up to 190 cm.
this is the platform: i need to calculate the force that push down on the lower arm when the platform about 45 degree....?

thats a BFF design, even his doesnt go to 45 deg.
if you want 45deg without AC motors, look at one of these
http://www.acesim.com/main.html . Built right you can have 45 deg.
I take it you are using for flight, not race.

no i dont think i need 45 deg but for the maximum load calculation .

BFF design uses 3 x 24v motors which would do the job, not sure about 45 deg angle though.
Sorry, I dont know

Or talk to people who are in the same process of design, like @cthiggin he might share the information on how much force is need by the motors in order to move the sim safely.

thanks to everybody! I got a lot of help here!

You stated you were doing a 2dof design correct? Cthiggin is doing a 3dof and needs much more power than a 2dof design. While this could be calculated mathematically, you would need a formula and all the correct values to plug in. A crude method (but accurate) would be to have a platform built already with everything that will be on it during actual sim use. If you have a scale to weigh with you could then tilt it to its maximum positions and weigh the off balance weight somehow at the point where your rods will connect at the platform. The highest weight reading obtained on each axis will give you the minimum ft lbs torque that will be required for each axis. Ft lbs is easily converted to nm or another standard using an online calculator.

Edit btw, the measurement obtained will only be equal to your motors minimum torque requirement if you are using a lever that is 1 foot (around 300mm). Since that is quite long and has to long of a throw for most applications, chances are you will use a shorter lever. If it is only 6 inches (150mm) long for example, then your motors minimum requirement would be one-half (times .5) the measurement obtained.

Whoops! This assumes you do you're measuring in pounds (lbs) also! You can convert kilograms to lbs though if necessary!