In the 1800’s, Augustin Louis Cauchy, a pioneer in mathematical analysis, studied the stiffness of an “articulated octahedron,” which is the ancestor of the hexapod. In 1949, V.E. Gough moved forward and built a parallel mechanism to test tires under combined loads. Few years later, in 1965, D. Stewart began using a variant of the hexapod for his flight simulators. The robot he made was renamed after him, the “Stewart Platform.” Over the years, the hexapod was upgraded by many engineers (K. Cappel, McCallion etc.).
Dynamics of the Stewart Platform
The mechanism is a kinematic structure composed of two platforms and six actuators. The base platform is fixed while the upper platform and the six struts are moving. The actuators of the upper platform are all connected to a link by a ball-and-socket joint; the other end of the link is attached to the base by a universal joint. All the actuators are independent from each another and orient and position the upper platform.