Spherically actuated platform manipulator

This article presents the inverse and forward pose and rate kinematics solutions for a novel 6-dof platform manipulator, actuated by two base-mounted spherical actuators. The moving platform is connected to the fixed base by two identical SPU serial chain legs. The S-joint is active, and the remaining two joints in each chain are passive. An analytical solution is presented for the inverse pose problems, a semi-analytical solution is presented for the rate problems, and the numerical NewtonRaphson technique is employed to solve the forward pose problem. Unfortunately, the passive joint variables cannot be ignored in the kinematics solutions as they can for the Gough/Stewart platform. Examples are presented and hardware has been built, using two Rosheim Omni-Wrists on loan from NASA as the spherical actuators.