Constraint analysis on mobility change of a novel metamorphic parallel mechanism

This paper presents a new metamorphic parallel mechanism that has the ability to change mobility in a wide range. Based on the newly invented reconfigurable Hooke joint with two distinct phases, the constraint forces are altered to be exerted on the platform. This change of constraint forces results in change of mobility of the mechanism and therefore degree of freedom of the platform. This paper applies screw system analysis, and by identifying both motion-screw system and constraint-screw system, the paper reveals six topological configurations with variable mobility. The particular phenomenon of bifurcated motion of the mechanism in its low-mobility configurations is further investigated based on constraint analysis.