| Soft robot has become a research hotspot in the field of robot due to their compliance,high adaptability and interactive safety.Soft gripper is a typical application representative of soft robot,but the soft hand made of pure soft material has weak load capacity and poor grasping stability,which limits its use.Therefore,a spring enhanced rigid-flexible coupling pneumatic soft gripper(hereinafter referred to as the coupling soft gripper)is designed to improve the load capacity and grasping stability of the soft gripper.In this paper,the structure design and manufacture of the coupling soft gripper,the mathematical modeling and finite element simulation analysis of a single finger,the system design and experimental research are studied,the main research contents are as follows:By coupling the spring with the pneumatic soft actuator,a kind of rigid-soft coupling soft finger is designed.The finger enhances its stiffness by the antagonism of the spring,so that the load capacity and stability are strengthened.Based on this,a modular design of a three finger adjustable grasping diameter coupling soft gripper is completed.It can realize the quick installation and disassembly of the finger,the gripper can meet different stiffness requirements by changing the spring with different stiffness.Based on the Yeoh constitutive model and the structural features of the finger,the deformation of the coupling soft finger is studied,and its energy change and transfer are analyzed.Finally,according to the law of conservation of energy,the mechanical model of the working state of the coupled soft finger is established,so as to explore the mathematical relationship between the bending angle of the finger and the air pressure.The FEAs of mechanical performance of a single coupling finger was carried out,and the effect of main geometric size on the performance of the finger was studied by using ABAQUS.The bending characteristics of the coupling finger and the soft finger under different air pressures are analyzed,and the bending angles of the two are compared and found to be reliable with the plan thoughts of this paper;the limited component examination comes about of the coupling fingers are reliable with the hypothetical show calculation comes about;and the particular investigation of each concentration position is inclined to happen.In addition,the influence of three structural parameters of the coupling finger(wall thickness,the spacing between two air chambers,the wire diameter of the spring)on the bending characteristics of the finger is systematically studied by the controlled variable method.A robotic pneumatic control platform was built.The bending performance,fingertip force and finger stiffness of the two kinds of fingers were tested.It shows that the load capacity of the coupling soft finger is enhanced compared with the soft finger,and with the increase of spring stiffness,the enhancement effect is more obvious,by experiment test.The maximum gripping force of two kinds of soft hand under different air pressure was tested.The results show that the gripping force of the coupled soft hand with a spring diameter of 0.8 mm is about1.5 times that of the soft gripper.The experiment of grabbing some common irregular objects in daily life proves that the gripper has strong grabbing adaptability,and can realize the stable grabbing of objects of different quality,shape,size and material. |
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