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.roneverhart.com/Jumbo-Deep-Sea-Deniz-urunleri-Pecete-Yuzu-u/