Design,Modeling And Optimization Of Deployable Gripper Based On Thick Plate Origami Structure

As the application field of robots becomes more and more extensive,the working environment becomes more and more complex,and the objects to be gripped are also more and more diverse,the traditional clamping device cannot longer meet the requirements of work tasks in some specific applications.For example,when grabbing a large volume target,the gripper is required to have a large gripping range,a large gripping force,a large rigidity,and a high gripping stability,which makes it suitable for large targets.The design of the gripper end gripper is very challenging.In addition,the large gripping range results in a large gripper size,which requires the gripper to have a folding and unfolding function to facilitate storage and transportation.Force and high stability require the holder to have good structural rigidity.The origami structure has the characteristics of unfolding and folding by the folding mechanism,and compared with the folding mechanism,scholars can freely design the crease arrangement on the paper,which can generate a large number of structural configurations.In response to the main problems of the traditional clamping device,an expandable gripper was designed based on the folding principle of the origami mechanism,and its performance analysis and optimization were carried out.The main contents are as follows:In view of the fact that the thickness of the panel cannot be neglected in the application of the traditional origami structure in the design of the gripper,resulting in the physical interference between the folding plates during the folding of the gripper,the motion principle of relative rotation and offset generated by the rolling contact hinge In order to solve the problem of interference between the various folding plates in the folding process of the thick plate origami,the thick plate origami structure has the same kinematic characteristics as the zero-thickness origami structure in the folding process.In order to apply the hinge to the thick-plate origami structure,a kinematic model of the hinge in a planar state is established,so that the contact profile function of the hinge is obtained.In order to illustrate the feasibility of rolling contact hinges applied to thick-plate origami structures and the correctness of the established contact surface function,rolling contact hinges were applied to single-apex four-crease origami units and Miura origami structures to obtain rolling at each crease The geometry of the contact hinge was prototyped and the two examples were prototyped.The folding of the example illustrates the feasibility of using rolling contact hinges to replace the creases in the design of the thick plate origami structure.Aiming at the problems that the traditional gripper has a small gripping range and insufficient gripping force when grasping large-sized objects,combined with the advantages of the origami structure,a malleable clip based on a thick plate origami structure is designed Holder.The holder consists of two Miura-Ori origami units sharing two origami plates side by side and placed symmetrically.Based on the contact profile function established in Chapter 2,the design of rolling contact hinge was carried out for the creases between each fold plate constituting the holder.In order to measure the performance of the gripper,the theoretical analysis of the gripping force and the end tensor of the gripper was carried out based on the principle of virtual work,and the mathematical model of the end tensor and the clamping force was obtained.In order to verify the validity of the design idea of the gripper and the correctness of the theoretical model established,a prototype was made according to each size parameter for experimental testing.The experimental results show that when the output force is 18.5 N,the actual mechanical benefit of the origami gripper is 0.3341,the theoretical mechanical benefit is 0.3571,and the error between the two is 6.44%,indicating the validity of the design idea of the gripper and the correctness of the model built.In order to further improve the gripping force performance and end tensor of the gripper,a sensitivity analysis was first performed to obtain the main dimensional parameters that affect the performance of the gripper and used as design variables.The relationship between the dimensions was used as a constraint and the maximum fold was obtained.Based on the angle and the maximum opening and closing amount,the maximum folding angle of the holder and the maximum opening and closing amount of the end are taken as the objective function.Establish the gripper optimization model and solve the optimization model.Through the operation output of the program,the results are rounded to obtain the upper bottom length of the trapezoidal folding plate that constitutes the gripper is 99mm,the lower bottom length is 228mm,the high line length is 99mm,the waist line length is 118mm,and the bottom angle?₁ is 57?,Dihedral angle ₁?is 119?.In order to illustrate the performance improvement of the gripper after optimization compared with that before optimization,a comparative analysis of the performance indexes of the gripper before and after optimization was carried out.The results showed that the amount of end tension of the gripper increased by 140%and the maximum folding angle?increased by 7.69%The results show that the optimized gripper's performance has been significantly improved than before,indicating the feasibility of optimizing the design of the gripper and the effectiveness of the optimization method.