Kinematics and dynamics of 2(3-RPS) manipulators by means of screw theory and the principle of virtual work

In this contribution the kinematic and dynamic analyses, up to the determination of the driving forces, of a specific class of series–parallel manipulators, known as 2(3-RPS) manipulators, are approached via the theory of screws and the principle of virtual work. The generosity of screw theory, and the simplicity of the principle of virtual work, allows to obtain systematically such fundamental analyses. As an initial step, the forward position analysis of the hybrid mechanism is presented in analytical form solution, thus all the feasible solutions, at most 256, can be easily obtained. Afterwards, the velocity and acceleration analyses, as well as the dynamic analysis, are simplified considerably applying the properties of reciprocal screws.