Structural Design And Optimization Of Planar

As an end-effector,micro-gripper is widely used in optical detection,biomedical and micro-nano manipulation fields.In order to realize the stable clamping of irregular micro-objects and avoid the falling-off damage of operating objects during the clamping process,it is important to design a micro-gripper with reasonable structure,fast response,high clamping accuracy and stable clamping.Aiming at the problems of 2-point contact planar clamping,such as easy instability,low clamping reliability and low clamping accuracy,a new 4-point contact micro-gripper is designed based on the principle of bridge amplification and lever amplification,and a geometric model is established.According to the amplification relationship between input displacement and output displacement,a mathematical model of the amplification coefficient of the micro-gripper is established,and the micro-gripper is determined.The theoretical magnification formula of the gripper is calculated and simulated by ANSYS.The results show that the gripper has larger gripping stroke and faster response speed.In order to improve the comprehensive performance of the micro-gripper,the finite element models with different design parameters are established by using the multi-objective optimization method of BP neural network model;the test points are selected by the Latin hypercube experimental design method,and the global mapping relationship between design parameters and performance indexes is derived by using BP neural network training,and the global search is carried out by multi-objective genetic algorithm.Optimal search operation is used to find the optimal design solution and determine the reasonable structural parameters.The results show that the natural frequency of the micro-gripper increases by 10.85%,the amplification factor increases by 7.15%,and the maximum stress decreases by 4.47%.The comprehensive performance of the four-point contact gripper has been significantly improved,which indicates that the optimization method has certain feasibility.In the control operation of micro-gripper,in order to reduce the influence of oscillation error caused by hysteresis of piezoelectric ceramics,the mathematical model of the operation platform is established.Simulink simulation is used to fine-tune the initial PID parameters of micro-gripper,which realizes the control of micro-gripper system by PID and outputs the step response curve of micro-gripper.By comparison and analysis,the results show that under the control of PID,the micro-gripper can enter the steady-state response more quickly,the number of system vibration is significantly reduced,and the overall stability is greatly improved.Aiming at the limitation of planar clamping,a symmetrical spatial micro-gripper is designed in this paper.The gripper can drive four clamping arms synchronously by piezoelectric ceramics to complete the clamping operation.The gripper has good clamping effect on irregular shape objects.The simulation analysis of the gripper is carried out by using Ansysworkbench finite element analysis software.The simulation results show that the gripper meets the requirements.The actual amplification factor and natural frequency of the gripper are 7.5 and 419.72 HZ under the condition of strength requirement.The gripper has fast response speed and gripping stability.It shows that the structure of the spatial micro-gripper is reliable and reasonable.