Research Of Polymorphic Origami Structures Based On Mobile Assemblies Of Spatial Reconfigurable Linkages

Engineering origami provides novel solutions to many engineering problems,such as large-scale space expandable structures,modular deformable structures,and mechanical metamaterials.Origami folding can transform a two-dimensional flat paper-like material into a three-dimensional structure,which could present these characteristics of foldability,light weight and polymorphic configuration.With the expansion of application field,multi-functional polymorphic origami structures obtain increasing attention comparing with the single-form origami structures,which makes the polymorphic origami structures become an inevitable research trend.Therefore,this subject studies the multi-form folding behavior of origami structures based on the derivation relationship between spatial mechanism and rigid origami structures,and this paper establishes an analysis method for the analysis of geometric characteristics of multi-form origami structures and kinematic behaviors of folding process,which will provide a theoretical basis for the innovative design and engineering applications of multi-form origami structures.First,the relationship between the multi-form folding performance of origami structure and the kinematic behavior of reconfigurable mechanism is studied.The equvialent principle between origami folding mode and the rotation behavior of the mechanism joints is established based on the rigid origami theory,and the multi-form folding behavior of a specific two-unit origami structure is analyzed by using the kinematic characteristics of reconfigurable Bricard linkages.According to the geometric conditions and motion constraints of origami structure,a reconfigurable double-loop mobile assembly of Bricard linkages is established.Based on the screw motion equation and DH parameter equation,the motion singularity of the double-loop linkage is analyzed.Accordingly,sixteen specific motion branches of the double-loop linkage with different spatial configurations are constructed and correspondence folding forms of the origami structure are obtiand,which verifies the equivalent relationship between the polymorphic folding of origami structures and the kinematic behavior of correspondence equvialent mobile assemblies of reconfigurable linkages.The symmetrical multi-form folding characteristics of the multi-cell waterbomb origami structure are studied based on a reconfigurable mobile assembly of spherical 6R linkages.According to the product of exponentials formula of the closed-loop linakge,the geometry properties and kinematic behavior of waterbomb origami base are analyzed,and the theoretical model of the waterbomb origami configuration is established through the transformation matrix method.The mobile assembly of two kinds of spherical 6R linkages is constructed according to the arrangement of these origami units,and the composition form of the motion braches of the reconfigurable linkage network is studied in detail.Thus,the folding forms of the origami structure derived from those motion branches are obtained and a modular origami gripper is proposed.The geometric analysis is carried out by using the transformation matrix method,as well as the capture characteristics.A prototype of rigid-flexible coupling origami gripper is developed,and paractical capture ability of the origami gripper is verified by emplying the cable-drive system.Further,a two-layer reconfigurable linkage network is established by mobile assembling two motion braches of the reconfigurable network of spherical 6R linkages,and a resulting double-pattern assembled multi-form and multi-stable origami structure is obtained.The geometry analysis and folding behavior of the origami structure are studied based on the kinematic performance of the two-layer reconfigurable linkage.Geometric compatibility of the origami structure is analyzed,and a cardboard origami physical structure is fabricated to verify.Based on the bending deformation theory of thin plate,the equivalent mechanical models of the elastic elements in origami structure are established and the deformation energy of origami structure during the movement process are studied,which verifies the bistable characteristics of the double-layer assmbled origami structure.A construction method of bimorphic and bistable origami structure is proposed and a3 D printing flexible material origami structure verifies this method.Based on the expandability of the origami structure,a multi-form origami structure with four forms and 128 folding forms are designed,and the Poisson’s ratio characteristics are studied.An artificial muscle with a multi-form origami structures skeleton is designed to explore the application of origami structures.Finally,the design and analysis methods of thick-panel origami structures are investigated because of the thickness of actual engineering materials.A specific thick-panel origami structure is deigned in details based on the hinge shift method,and the influence of panel geometric parameters on the configuration characteristics is studied.Based on the kinematically equivalence between the thick-panel origami units and spatial overconstrained Bricard linkages,a mobile assembly of spatial Bricard linkages is constructed.The degree of freedom of the linkage network is analyzed according to the screw motion equation,and the kinematic characteristics of the thick-panel origami structure are given.Then,a spatial deployable thick-panel origami structure with parabolic surface is designed,as well as the corresponding mobile assembly of Bricard linkage.The relationship between geometric parameters and configuration characteristics is analyzed in details.A prototype of thick-panel origami structure with parabolic surface is developed to verify the design process and theoretical analysis.