High-efficiency Nonlinear Topology Optimization Design And Experimental Research Of Origami Flexible Mechanical Claw

Flexible mechanical claw,having the advantages of humanoid manipulation of fragile objects,prevention of hard impact or jamming in continuous space movement,more accurate human-machine interaction in remote operation and high operation safety.The key of these advantages lies in its flexibility and effective configuration.And the origami structure takes into account both rigidity and flexibility.Its rigidity and portability can make it have better maximum gripping ratio,while its flexibility(large volume expansion ratio)can make it have better clamping adaptability;Origami structure also has the advantages of simple concept,simple preparation(less assembly or even no assembly)and low cost.Its application in flexible mechanical claws has many advantages.Therefore,this paper takes the origami flexible mechanical claw as the research object.In addition,topology optimization has the ability to change the layout of structural materials and the form of topology connection,which can greatly obtain the structure with superior performance,and provides an innovative means for the design of flexible mechanical claws.Due to the need to repeatedly perform operation tasks,flexible mechanical claws generally use hyperelastic materials,and their work often needs large geometric deformation.In order to obtain a more reasonable optimal configuration,nonlinearity should be considered in the process of topology optimization design.However,in order to reduce the computational complexity,reduce the computational cost and avoid the difficulty of convergence,most of the current research on the topology optimization design of flexible mechanical claws is based on linear topology optimization.Based on this,a multi-resolution nonlinear topology optimization method with high computational efficiency and good solution convergence is proposed in this paper.And it is applied to the configuration design of origami flexible mechanical claw to efficiently and reasonably design a flexible mechanical claw with better comprehensive grasping performance,which is verified by experimental research.The main research work is as follows:(1)A multi-resolution nonlinear topology optimization method with high computational efficiency and good solution convergence is proposed.The proposed method considers both material nonlinearity and geometrical nonlinearity,uses Neo-Hookean hyperelastic model to characterize material nonlinearity,and solves the problem of non-convergence of geometrical nonlinearity with the help of additional hyperelasticity material technology.In order to simplify the nonlinear finite element solution and sensitivity solution,the commercial software ANSYS is used for finite element calculation.Aiming at the big problem of repeated iterative calculation in the process of nonlinear topology optimization,an efficient and accurate multi-resolution solution strategy is proposed.The rough grid and fine grid are used to calculate the finite element and describe the material distribution,respectively.The rough grid can reduce the number of finite elements and avoid the emergence of smaller finite elements.On the one hand,it can improve the computational efficiency;on the other hand,it can further enhance the ability of additive hyperelasticity material technique to solve the iterative non-convergence of nonlinear topology optimization,and then it can efficiently realize the nonlinear topology optimization of three-dimensional structure.(2)An optimal design method of origami flexible mechanical claw based on multi-resolution nonlinear topology optimization is developed.The developed method takes the two-dimensional form of multi-material origami flexible mechanical claw as the initial configuration,takes the volume as the constraint and the maximum output displacement as the goal,and carries out multi-resolution nonlinear topology optimization design for the crease material with deformation.Among them,the multi-material origami flexible mechanical claw can fold and unfold with low stiffness material as crease and high stiffness material as panel.Finally,based on the optimized configuration,the crease material is cut on the flexible sheet,and the flexible mechanical claw of single material origami can be simply manufactured.This method can not only give full play to the advantages of origami structure applied to flexible mechanical claws,but also efficiently and reasonably design the crease material distribution with better deformation performance.In addition,it can realize the simple manufacture of origami flexible mechanical claw,which is conducive to the universal application of origami flexible mechanical claw.(3)An origami flexible mechanical claw with better comprehensive grasping performance is designed.Using the developed optimization design method of origami flexible mechanical claw,a kind of origami flexible mechanical claw is obtained and experimentally studied to explore its comprehensive grasping performance.Firstly,a comparative experimental study is carried out on the optimization objectives.The effectiveness of the optimization is verified by comparing the grasping range of the multi-material origami flexible mechanical claw before and after the optimization under the same load.On the one hand,under the same load,if the mechanical claw does not reach the upper limit of the grasping range,the grasping range of the optimized mechanical claw is wider;On the other hand,if the end point of the mechanical claw is to reach the same grasping position,the grasping speed of the optimized mechanical claw is faster.Secondly,the experimental study on the maximum grasping ratio of origami flexible mechanical claw shows that it has a better maximum grasping ratio and can grasp an object nearly 30 times its own weight.Finally,the origami flexible mechanical claw is installed at the end of the manipulator.The grasping experiment shows that it has good grasping adaptability to objects with different shapes,sizes,weights,stiffness and orientations.