Modeling Of Soft Pneumatic Gripper And Its Grasp Performance Optimization

In recent years,soft robots have become a research hotspot in the field of robotics.As an important component unit of soft robots,a soft actuator has the advantages of good flexibility and strong adaptability,and is widely used in the fields of object grasping and medical services.However,because the soft actuator has material nonlinearity and geometric nonlinearity,its kinematics modeling is generally combined with experiments to obtain numerical formulas containing a large number of empirical parameters,which is difficult to perform parameter optimization analysis.In order to establish a mathematical model describing the bending deformation of a soft pneumatic actuator,the simplified Yeoh model is used to establish its active bending deformation model.Then based on the chained beam constraint model,the relationship between its equivalent end force,moment and stiffness and air pressure is obtained by fitting,which verifies the accuracy of the chained beam constraint model whose parameters change with air pressure to describe its bending deformation.The main research contents are as follows:(1)The simplified Yeoh model was used to establish the energy density function of the silicone material,and the material parameters of the silicone were measured by the uniaxial tensile test of the silicone sample.Based on the Abaqus,the finite element simulation of the bending characteristics of the soft pneumatic actuator under different air pressures were analyzed,and the maximum stress surfaces of the soft pneumatic actuator were obtained by analyzing the simulation results.(2)Based on the geometric structure of the soft pneumatic actuator,referring to the Abaqus simulation deformation with constant curvature,a mathematical model of the active bending of the soft pneumatic actuator was established,and the relationship between its end rotation angle and the geometric structure parameters and air pressure P was determined.The obtained active bending deformation curve is compared with the finite element simulation results,and the maximum error does not exceed 5%,which verifies the correctness of the theoretical model.Under the condition of keeping the air pressure constant,the structural geometry parameters of the soft pneumatic actuator were optimized to obtain a larger bending angle.The deficiencies of kinematic model of soft pneumatic actuators using the assumption of segmented constant curvature and Yeoh model were analyzed,and the necessity of establishing a general model was clarified.(3)Based on the chained beam constraint model(CBCM),combined with the Abaqus finite element simulation of the active and passive bending deformation data of the soft pneumatic actuator,through fitting,the quadratic function relationship between the equivalent end force fo,po and bending moment mo of the soft pneumatic actuator and the air pressure P was obtained,and the equivalent stiffness matrix coefficient has a linear function relationship with the air pressure P.The average fitting error in the range of medium and low pressure(0?45kPa)dose not exceed 10%,which verifies the accuracy of the improved CBCM to describe the active and passive bending deformation of the soft pneumatic actuator.(4)The mold structure of the soft pneumatic actuator was optimized and manufactured by 3D printing technology,and the manufacture of soft pneumatic actuator was completed.The pneumatic experiment platform was built,and the active and passive bending deformation experiments of soft pneumatic actuators were completed,which verified the accuracy of Abaqus finite element simulation and the theoretical model built.Based on the optimized soft pneumatic actuator,a soft pneumatic manipulator was designed and manufactured,and a large number of gripping experiments were conducted to verify the reliable and stable gripping performance of the soft pneumatic manipulator designed in this paper.