Type synthesis of metamorphic and axisymmetric parallel mechanisms using singularity for deployment and latch

Abstract

Existing deployable mechanisms and metamorphic structures realize the latch ability with extra design or contact force. However, these designs limit the workspace and loading capacity. Here, we proposed an approach to the type synthesis of metamorphic and axisymmetric parallel mechanisms using singularity for deployment and latch. The singularity enables the mechanism to change its configurations between deployment and latch states through the local degree of freedom on chains. Based on screw theory and linear algebra theory, the type synthesis progress was divided into four numerical steps: the classification of screws for axisymmetric; the calculation of motion screw bases on chains; the limitation of combination coefficient for pairs and singularity; and motion verification of different configurations by exerting displacement differentials. According to the type synthesis, we presented three types for various motions respectively calculated from MATLAB. The kinematics and dynamics analysis of the three types simulated in “Solidworks Motion” proved the deployment and latch abilities. This numerical method is also available for synthesizing mirror-symmetry parallel mechanisms with various restraints by changing the classification of screws and limitation of combination coefficient.