Grasping Performance Evaluation And Intrnsic Force Sensing Method For A Compliant Adaptive Gripper

As one of the main end-effectors of the robot,the performance of the manipulator has an important influence on the robot to complete the tasks and meet the needs of people.Traditional rigid manipulators,most of which are grippers with rigid linkage mechanism or clamping jaws,have the advantages of simple structure,convenient operation,good rigidity,high precision,large clamping force,firm grip and good reliability.But it is difficult to form a reliable envelope on the object due to its poor flexibility which limits its work scene.When it is necessary to gr asp soft and fragile objects,the rigid manipulator is likely to cause damage to the object due to excessive grasping force,or fail the grasp because the grasping force is not large enough.Because of the passive flexibility,the flexible hand has shape a daptability to objects of any shape and any size.In application scenarios such as vegetable and fruit picking,it has obvious advantages over traditional rigid manipulators,and more and more people’s attention.However,accurate modeling of flexible grippers or flexible fingers is a relative difficult challenge.At present,finite element analysis or Cosserat rod model is mostly used for gripper modeling of flexible materials,while for underactuated fingers with rigid materials whose structure is basically fixed,mostly use pseudo-rigid body modeling.This paper firstly proposes a structural design idea for the shape-adaptive bionic Fin-ray gripper of the rigid material with flexure hinge,which is to find the material and technology to realize the shape-adaptive bionic Fin-ray gripper made of rigid material with flexible hinge,and the prototype of the bionic Fin-ray gripper is made.The bionic Fin-ray gripper designed in this paper is different from the conventional shape-adaptive bionic Fin-ray gripper made of integrated flexible materials or the under-actuated bionic Fin-ray gripper realized by a rigid linkage mechanism.It is a combination or rigid and flexible materials.The combination of materials has the characteristics of good flexibility of flexible materials and good rigidity of rigid materials.For this type of gripper,two static models based on the finite element frame model and a pseudo-rigid-body model based on the principle of virtual work are proposed.The proposed statics model can realize modeling of Fin-ray gripper with any given number of phalanges according to the actual design.Geometric analysis of the bionic Fin-ray gripper can be calculated and its reachable working space is combined with the proposed two static models to propose evaluation metrics as a guide for the design of the bionic Fin-ray gripper.The finite element model in this paper is different from the previous finite element models based on flexible manipulators.It is a static modeling of the shape-adaptive manipulator made of rigid material with flexible hinges.The pseudo-rigid-body model based on the principle of virtual work is also different from the static model established for the rigid linkage mechanism in the past.It is a static model of a rigid material manipulator with flexible hinges.The correctness of the two static models was verified through single-finger Young’s modulus calibration and force perception experiments,and two-finger gripping force perception experiments.The experimental results show that the two static models proposed are in good agreement with the real finger force and deformation,and can meet the requirements of specific application scenarios.