Spatial quadric mechanism design for hinge relocation using extension of DOF in singular configuration

Movable structures can change their shape because each of the components are connected by hinges. This paper discussed a mechanism design method that can relocate hinges based on a fourbar linkage mechanism. In this paper, "structural fabric" is defined as the arrangement of the hinges, and "shape" is also defined as the structural externals made from the arrangement of the hinges. By this definition, changes of the shape by the hinge's angle without changing the hinge arrangement is different from changes in the structural fabric. On the other hand, origami can transform by changing its structural fabric because it can freely relocate creases as hinges. However, there have been no rigid body structures that have origami-like characteristics, since there has been no mechanism that can relocate hinges. So we have designed HDRM (Hinge Double Relocation Mechanism) which can relocate hinges, and have constructed movable structures by combining the HDRM. Contents of this paper is as follows; First, a mechanism design requirement that can relocate hinges by the planar linkage have became clear. The design requirement has been expanded to spatial linkage mechanisms which have been named HRM (Hinge Relocation Mechanism), through the mechanical analysis of the spherical quadric crank chain mechanism. Next, the HDRM that relocates hinges in a singular configuration has been invented by adapting the mentioned requirement. The requirement of making movable structures from HDRM has been cleared by solving the Hamiltonian path problem. Finally, from evaluations using kinematical and interference analysis on the 3D-CAD, it has been confirmed that the constructed movable structures can change into various shapes by changing the structural fabric.