Research On Grasping Performance Of Airbag Finger Pad

With the continuous development of the times,the grasping and operating tasks of manipulators are becoming more and more diversified.In agricultural,industrial and home environments,the demand for robots to grasp and operate soft and fragile items without damage has been increasing.The traditional rigid manipulator is difficult to meet the demand for flexible grasping of soft and fragile objects in the process of grasping and operating.Although the traditional flexible manipulator can grasp some objects flexibly,the grasping force is very small,and the grasped objects are easy to slide down,which is difficult to meet the needs of grasping tasks.In order to solve these problems,this study design and manufacture a finger pad test device to study the grasping performance of the airbag finger pad and carry out related experiments.Aiming at the working requirements of the airbag finger pad,the finger pad test device is designed.The tensile test of the silicone material for making the finger pad was carried out.After obtaining the stress-strain curve,it was fitted with different constitutive models.The appropriate constitutive model was selected to obtain the relevant model parameters,which provided the basis for subsequent finite element analysis.The finite element model of the finger pad and PLA rod is modeled,and the geometric model,material properties,boundary conditions,meshing and initial conditions are set and analyzed accordingly.The required inflation function is established to keep the internal gas volume constant after inflation and then carry out subsequent contact.The error analysis of the internal pressure and the expansion height of the finger pad after inflation using the established inflation function is carried out.Finally,the finite element analysis of the contact is realized,and the contact area of the finger pad clamping PLA rod under the given conditions is obtained.Considering the grasping of heavy objects,when modeling the grasping finite element model of the finger pad,the material of the rod is replaced by a steel rod based on the contact finite element model of the finger pad and PLA,and its related settings are adjusted accordingly.Considering the problem of friction coefficient during grasping,the friction coefficient between the finger pad and No.45 steel was measured by a plane friction coefficient meter using multiple measurements to obtain the average value.The friction coefficient was applied to the contact condition.When the initial conditions were analyzed,a grasping process was added on the basis of the contact in the previous chapter,that is,the corresponding displacement function was applied to the steel bar after contact with the finger pad.Finally,the finite element analysis of grasping is realized,and the grasping force of finger pad grasping steel bar under given conditions is obtained.Different clamping forces and rods with different curvatures are selected as influencing factors,and their values are selected respectively.After that,the contact finite element model and the grasping finite element model of the finger pad established before are used to clamp or grasp the rods with different curvatures by different clamping forces,and the change rules of the contact area and the grasping force are obtained.The existing finite element analysis data of the contact between the finger pad and the PLA rod were tested and verified,the corresponding test device was manufactured,and the relevant experimental platform was designed.The tensile testing machine was used to apply different clamping forces to the PLA rod for contact experiments.The contact area between the finger pad and the PLA rod under different clamping forces was calculated by multiple measurements.Finally,the experimental data are compared with the finite element analysis data to verify the accuracy of the finite element analysis results.