Research On Key Technologies Of Lamina Emergent Mechanism

Lamina Emergent Mechanisms(LEMs)are a new type of compliant mechanism which can be fabricated from planar materials and have motion that emerges out of the fabrication plane.Compared with other complaint mechanisms,the performances of LEMs have been improved obviously.On the one hand,LEMs can be fabricated at low manufacturing cost.On the other hand,LEMs have flat initial state for compact packing and shipping,which means a significant reduction in the cost of handing,storing,and shipping for high volumes of devices.In addition,LEMs which have wide applicant backgrounds can perform sophisticated mechanical tasks with simple topology.However,the research of LEMs is still in the early stage.The lack of component units and analysis method seriously hampered the development of LEMs.Hence,the key technology of LEMs includes analysis method and flexure hinge structure is researched in this paper.The main contents of this paper are as follows:Firstly,a new fixed-guided 6R pseudo-rigid-body model(PRBM)is presented based on the principles of PRBM.The kinematics equation of the model is set up,and the optimal characteristic radius coefficients and the spring stiffness coefficients are acquired using the inverse kinematical analysis.The correctness of the model is validated by finite element analysis and engineering examples.Secondly,a new tensile compressive inside LEMs flexure hinge is proposed for lamina emergent mechanisms to improve the axial stiffness of inside LET flexure hinge based on the inversion principle.The theoretical model of the equivalent rotational stiffness and equivalent tensile compressive stiffness are presented respectively.Then the rotational precision of the tensile compressive inside LEMs flexure hinge is analyzed using center-shift.Meanwhile,the superiority of the tensile compressive inside LEMs flexure hinge is proved by comparing with the inside LET flexure hinge which has the same size as the tensile compressive inside LEMs flexure hinge.Then,in order to increase the flexibility of LEMs,two kinds of multiple degrees of freedom LEMs flexure hinge are designed.Theoretical models of equivalent stiffness of the LEMs flexure hinges are deduce.By comparing the theoretical calculation results with finite element simulation results of the design example,the validity of the theoretical calculation models is proved.In the meantime,the impact of structural parameters on the equivalent stiffness is discussed in detail.In order to enhance the rotational capacity and rotation accuracy of the LEMs flexure hinges,the optimization models are constructed,and structural parameters are optimized based on particle swarm algorithm with penalty function.As a result,the properties of the LEMs flexure hinges are improved significantly.Finally,a multiple degrees of freedom spatial gripper is proposed.The model of the amplification ratio based on flexible deflection is analyzed,and the validity of the model is also verified.Meanwhile,the change rule of the gripping orientation is researched.And the atlas of the reachable workspace is listed on account of the construction of the front-end.The feasibility of the spatial gripper is proved.