Design And Experimental Study Of Biomimetic Flytrap Flexible Gripper Driven By Magnetorheological Fluid

In recent years,forestry resources have been greatly reduced,among which diseases and pests are one of the important factors of forest resource loss,and the development of forest pest capture equipment can greatly improve the capture efficiency.Flytrap is one of the few plants that can catch insects quickly,and the grasp is fast and reliable.With the development of research and exploitation,flexible gripper technology makes it possible to imitate the grasping action of flytrap grass and develop forest pest grasping equipment,but the flexible gripper is limited by the rigidity of the material,which is easy to lead to grasping failure,and the complex variable stiffness structure leads to increased research difficulty.Therefore,this paper takes flytrap as the main research object,studies its physiological structure and movement mechanism,and develops a bionic flytrap flexible gripper driven by magnetorheological fluid,which analyzes the bending grasping angle,grasping force and stiffness change range through simulation and experiment.Firstly,the biomimetic leaf structure is designed based on the physiological structure and bending movement mechanism of flytrap.Flytrap grass relies on the internal flow channel of the leaf to realize the bending and grasping of the leaf,and the grasping action consists of two parts: the preparation stage and the rapid bending stage,which can improve the success rate of grasping.By analyzing the physiological structure and movement mechanism of flytrap,the structural size parameters of bionic leaves were obtained after simplifying the leaf structure of flytrap grass and magnifying the leaf size by 5 times,and the bionic blade arranged by multichamber array and the flexible gripper structure of bionic flytrap composed of two identical bionic leaves were developed.Molds and fixtures are manufactured using 3D printing technology,and prototypes are made by silicone pouring.The magnetic effect and working mode of the magnetorheological fluid,as well as the performance of the magnetorheological fluid,the magnetization characteristics and magnetization strength under a uniform magnetic field,were analyzed,and the possibility of magnetorheological fluid drive was judged.Secondly,a simulation and theoretical model are established for the design structure to analyze the bending performance of the bionic blade.Abaqus was used to analyze the spatial bending angle of the whole bionic blade and the corner nodes of each chamber,establish a simulation model of the bionic blade under different pressures,analyze the influence of the incomplete chamber with and without edges on the bending angle and strength of the bionic blade,and determine the rapid bending pressure of 0.04 MPa of the flexible gripper.The relevant kinematics and static analysis of the bionic blade were carried out,the corresponding assumption of the bending angle of the bionic blade was made by the segmented constant curvature method,and the relationship between the pressure and the bending angle of a single chamber and a single row of chambers was theoretically calculated and analyzed,and the theoretical model of the bending pressure relationship of the bionic blade was established.The transformation model is established for the stiffness change of the bionic blade,the relationship between the stiffness of the bionic blade and the external magnetic field is derived,and the possibility of the variable stiffness of the magnetorheological fluid drive is judged.By analyzing the gradient model of the Helmholtz coil,the gradient expression of the uniform magnetic field of the bionic blade on the axis of the circle center is established,and the field strength of the bionic blade at each point in the coil is determined.Then,an experimental platform was built to verify the performance of bionic blades and flexible grippers by conducting bionic blade characteristics experiments and flexible gripper grasping experiments.The characteristic experiment proposes a preparation pressure of0.01 MPa for the flexible gripper,which proves that although the magnetorheological fluid drive will reduce the bending angle of the flexible gripper,it will greatly improve the closing force of the flexible gripper of bionic flytrap,and the closing force is increased by 104.43%,which proves that the stiffness of the bionic blade can be effectively changed by changing the control magnetic field size by current.The grasping experiment proves that the load capacity of the flexible gripper structure reaches 304.3g,and there is a large room for improvement,the envelope grasping method can effectively improve the grasping stability of the flexible gripper,and the grabbing force of the envelope grabbing table tennis ball is increased by 48.19%,which proves that the flexible gripper can achieve bending grasping and can achieve variable stiffness under the action of magnetic field.