This paper describes the kinematics and dynamics modelling of a mechanical system consisting of a spherical inverted pendulum whose base is mounted on a parallel planar mechanism. better known as a five-bar mechanism. The whole mechanism has four degrees of freedom. but it has only two actuators and so it is an under-actuated system. https://www.jmannino.com/mega-pick-NFL-San-Francisco-49ers-Zone-Block-iPhone-14-Pro-MagSafe-Case-p80213-quick-pick/