The decoupling of the direct kinematics of parallel manipulators using redundant sensors

The effect of redundant sensors in the solution of the direct kinematics of general parallel manipulators is studied here, for purposes of online implementation. We describe three measurement conditions under which the kinematic relations are linear and hence, a linear decoupling of the position and orientation of the direct kinematics is possible. For each condition, a decoupling equation is derived and used to reduce the direct kinematics to an orientation problem only. The latter is solved by resorting to the polar-decomposition theorem. The numerical accuracy and efficiency of the procedure are also investigated