I am aware of various different approaches of kinematic modelling of parallel mechanisms. I have currently employed the vector loop closure equations to solve the inverse kinematics problem. The problem is, the vector loop closure method eliminates the passive joint variables. I need to see how these are behaving while I proceed with dynamic modelling. Are there any textbook methods that are capable of estimating all the joint variables? (active + passive)
After you calculate the joint angles, you can go back to each kinematic chain connecting the platforms ans solve the "inverse kinematic problem" of the kinematic chain only.
The base frame of the chain has known coordinates, the end of the chain should have known coordinates and the already calculated active joint angle can be used to reduce the number of unknowns.