Structural synthesis for a lower-mobility parallel kinematic machine with swivel hinges

• Develop the parallel mechanism with swivel hinges into a series.
• Study single open chain based on position and orientation characteristics.
• Construct mechanisms of different degrees of freedom with single open chain.
• Get and verify the inverse general solution with single open chain for the series.

In this paper, a novel parallel kinematic machine is proposed. Its active platform (main supporting spindle) is manufactured with swivel hinges, that is, we substitute the spherical hinge with a swivel hinge. The active platform is also divided into several layers, which alters the characteristics of a single-layer-platform parallel machine. This paper applies a comprehensive structural approach based on position and orientation characteristics (POC). Each single open chain (SOC) is studied independently from the whole mechanism; we also analyse the POC of each kinematic pair. By the method of union, we obtain the POC matrix of the output motion of each link. Based on the verification of the 5-DOF (degree of freedom) parallel kinematic machine, we construct 3-DOF and 4-DOF parallel mechanisms with swivel hinges through the combination and union of different chains, and develop them into a series.