Design And Performance Study Of Two-finger Soft Hand With Two Grasping Modes

Soft hand has unique advantages in grasping fragile and irregular objects,and the research on soft hand has important theoretical and application value.In this paper,the design,modeling and characteristics of Pneumatic Networks and soft hand are studied.The main work is as follows:A two-finger soft hand with two grasping modes of enveloping and pinching is designed.The soft hand is composed of two Pneumatic Networks with two modules and variable chamber height.Compared with other Pneumatic Networks,the actuator with variable chamber height has larger output force.By controlling the air pressure of the two modules,the pneumatic actuator can realize enveloping and pinching grasping modes.In pinching grasping,the high passive flexibility of the pneumatic actuator allows a larger contact area and the vertical plane contact with the object,which improves the grasping reliability.Pinching grasping is suitable for grasping small and medium-sized objects.In enveloping grasping,the pneumatic actuator becomes Pneumatic Networks actuator with variable chamber height,which has greater grasping force and is suitable for grasping large and hollow objects.The designed soft hand can overcome the problem of grasping asymmetry of the universal soft hand.In order to improve the output force of pneumatic actuator,a kind of cable and pneumatic dualdrive soft actuator is designed,which greatly improves the output force of the actuator without damaging the actuator.The analytical model for bending Pneumatic Networks is established.The model links the input pressure with the bending angle in free space and the tip force of the Pneumatic Networks.The bending angle of the actuator is studied considering the deflection of the gap layer of the actuator.The tip force of the actuator is analyzed considering the equilibrium moment of the actuator at the applied pressure.The proposed model considers the deformation of the lateral wall of the chamber as the deformation of the nonlinear hyperelastic membrane rather than a rigid plate.Finite element analysis and experimental results show that the bending angle and tip force of Pneumatic Networks can be effectively predicted by using the analytical model.Based on the finite element analysis,the bending angle and output force of the pneumatic actuator,the contact force and the contact area between the pneumatic actuator and the object in the pinching grasping are analyzed.Through the grasping contrast experiment,it is proved that the designed soft hand can grasp the object with vertically plane and has better grasping ability.Experimental results show that the two-finger soft hand can reliably grasp objects of various shapes and volumes.