5 FSF of Parallel- and Hybrid-kinematics Machines

In the two past decades, the parallel kinematics mechanisms (PKMs) have received wide acceptance for the design of robots and machines of different types. In these mechanisms, the output link – end-effector (EE) – usually presents a multi-degree-of-freedom platform (Fig. 5.1), which is directly and simultaneously (in-parallel) connected with another link (e.g., a fixed base) through several independent kinematic chains. Two parallel chains together with the base and platform form a kinematic closed loop. This fact explains the presently accepted definition of a generalized parallel manipulator, a closed-loop kinematic chain mechanism whose end-effector is linked to the base by several independent kinematic chains [1]. It should be emphasized that introducing the PKMs into real engineering projects has been made possible only by the simultaneous emergence of the modern computerized control systems.