THE SINGULARITIES AND DYNAMICS OF A STEWART PLATFORM MANIPULATOR

The Stewart platform manipulator is a fully parallel kinematic linkage system that has major mechanical differences over typical serial link robots. Its closed kinematic chain and parallel linkage structure giv e it great rigidity and a high force-to-weight ratio. In this paper, b ased on the forward and inverse kinematic analysis, the Jacobian matri x and the dynamic equations of the six-degree-of-freedom Stewart platf orm are derived. The singularities of the Stewart platform are also st udied. Four singular positions are proved and some other conditions un der which the possible singular positions may occur are given. These r esults provide us with the necessary information to avoid passing thro ugh singular points. The dynamic equations in Cartesian space appear i n a very simple form. Especially in some applications if there is no r otation about the fixed X-axis, then the 'inertia matrix' reduces to a constant, diagonal matrix and the 'Coriolis and centrifugal matrix' g oes to zero, which makes the Stewart platform become a decoupled, line ar system in Cartesian space.