I am trying to develop a statics free body diagram of a stewart platform 6dof parallel manipulator motion table. I have the base points (B1,B2,B3,B4,B5,B6) and the top platform points (P1,P2,P3,P4,P5,P6). I want to find the resultant force on each leg actuator based on the force of the payload, or table. I started with sum of moments = 0, and sum of forces = 0, but I am not sure how the upper joint forces are related to the lower joints based on the angles. The platform has ball and socket legs, which means no moments on the legs, which confuses me even more.
I searched the internet high and low and could not find any related force diagrams. Any help is appreciated.