Theoretical And Experimental Research On Origami-Inspired Compliant Mechanisms

Due to the limitation of the manufacturing capacity of,most compliant mechanisms with three-dimensional complex structures have relatively bulk structures,and most of their motion forms are restricted to plane motions.They still face many challenges in miniaturization and complex spatial movement.Because the origami mechanism can realize out-of-plane motion,scholars have proposed many spatial-compliant mechanisms inspired by origami,providing new design ideas for small-scale compliant mechanisms with complex spatial functions.However,most of the origami inspired mechanisms are based on the perspective of rigid mechanisms,and there are few systematic studies on the stability phenomenon,under-actuation phenomenon and design method of crease hinges.Under this circumstance,this thesis takes the origami inspired compliant mechanism as the research object,and launches the following research:(1)Aiming at the origami-inspired compliant mechanism with symmetrical motion characteristics,a steady-state comprehensive analysis method based on the internal potential energy function of the mechanism is proposed.This method firstly uses the symmetrical motion of the mechanism to establish a kinematic model,and then combines the internal potential energy function and the steady state criterion to derive the steady state condition of the mechanism and the parameterized equation of the steady state phase diagram.Finally,through the analysis of stiffness ratio,zero angle of potential energy and steady-state phase diagram,analysis and reverse design of the steady-state of the mechanism.Through the case analysis of typical origamiinspired compliant mechanisms,namely kaleidocycles origami-inspired compliant mechanisms and waterbomb origami mechanisms,the effectiveness of this method is demonstrated.(2)Aiming at the origami-inspired compliant mechanism with general motion constraints,a steady-state and underactuated kinematics analysis method based on augmented Lagrangian functionals is proposed.This method uses Hamilton's basic principles and Lagrangian function,and considers the implicit constraints of the mechanism to obtain the steady-state position of the mechanism and the under-actuated equation of motion.Based on this method,the case analysis of the kaleidocycles-8R mechanism with four basic units illustrates the correspondence between bifurcation motion and steady state,and proves the symmetrical motion principle of the compliant kaleidocycles mechanism under symmetrical configuration;Numerical calculation and verification of the underactuated kinematics model of the waterbomb-6R mechanism with the hinge stiffness of the crease vertex in the steady-state neighborhood has been carried out,which shows the effectiveness of the method.(3)Aiming at the hinge design problem of origami-inspired compliant mechanism,based on adjoint transformation and flexibility matrix method,a corresponding LES compliant hinge design method is proposed.In this method,the flexibility matrix of the LES flexible hinge with a given topology is assembled by adjoint transformation.In addition,the compliance ratio of the compliant hinge in each direction is analyzed and optimized by separating and normalizing the out-of-plane and in-plane geometry parameters of the LES compliant hinge.Based on this method,a variety of LES compliant hinges were designed,and a typical origami-inspired compliant mechanism design and experimental verification were carried out using this hinge.The research content of this thesis provides practical research ideas and solutions for many key issues,such as steady-state analysis,reverse design,underactuated kinematics analysis,and compliance hinge design in origami-inspired compliant mechanisms.This theory has important meaning and value for the theory of origami mechanism and compliant mechanism.