Help wanted - regarding Stewart Platform

Dear Mr.Vinay Warrier,

Please refer a Machine design book for "Power screws" topic.

Since I use Schaum series-"Machine Design" by Hall,Holowenko,Laughlin, I suggest you look up page 148 onwards for guidance from "Solved Problems", to get at the required Torque to be applied on the screw (that you propose to use:May I suggest a Ball screw), you will be able to choose an appropriate Geared Motor to be coupled for driving/actuating the screw.

Please also remember that besides direct axial loading on the screw, there will be Moments due to twisting of the entire stewart platform assembly and coriolis forces to be accounted for before finalising on the Kw rating of the actuation motor. I'd suggest D.C. motor as the response characteristics are better suited for Load pick up in the low RPM range and also linearity for Control. Of course, a Servomotor+control system will be the best if initial costs are not a constraint.

I hope this is found useful.

Regards

D.Ramakrishna Naidu

I have been looking up the web for servo motor + drive systems. Also, I have been trying to understand the Inverse dynamics of the platform for better understanding of the torques and velocities. I shall look up the resources you have mentioned. Thanks.

Regards

Vinay

http://kai-dranzer.livejournal.com

Look the following links for references about parallel mechanisms:

http://www-sop.inria.fr/members/Jean-Pierre.Merlet//merlet_eng.html

http://robot.gmc.ulaval.ca/en/index.html

Hi,

You need to specify not only the load but also the needed acceleration!

And the maximum stroke. And the maximum velocity, and duty cycle and so on.

Then select a motor and a gear and the screws pitch that seem suitable and make a tradeoff in performance and cost to the next bigger and the next smaller motor.

This will tell you what to do.

(I can do this for you but this would require a contract and payment.)

RHABE