Design And Experiment Of Variable Stiffness Gripper

As an important branch of soft robot,soft gripper is usually composed of hyperelastic material,which can show good safety and human interaction when facing some fragile objects with irregular shape due to its material speciality.However,at the same time also because of the low stiffness of the constituent materials,resulting in a low load capacity of the general soft gripper,it is difficult to extract some objects of large mass,limiting the application space of the soft gripper.In this paper,a soft body gripper with variable stiffness based on layer jamming structure is designed and studied in detail in terms of structural design,fabrication process,bending performance,and stiffness adjustment,etc.The main research contents are as follows.The structural design of the actuator part and variable stiffness part of the soft body gripper is carried out,and the composition materials and fabrication process of the soft body gripper are described in detail.The material parameters of the silicone material used are obtained through uniaxial compression test and theoretical analysis;the bending of the actuator part of the soft finger is obtained through simulation analysis to verify the rationality of the structural design of the driving part;the relationship between the bending angle of the soft finger and the magnitude of the internal positive pressure is obtained through experiment and the related curve is drawn;the function relationship between the bending angle and the magnitude of the internal positive pressure is deduced through moment balance and compared with the experimental data to verify the relationship between the bending angle and the magnitude of the internal positive pressure.The mathematical model was verified by comparing the data with the experimental data.The maximum load capacity of the soft gripper under different negative pressures was measured by building an experimental platform,and the change of the stiffness of the soft gripper under different negative pressures was obtained by analyzing the experimental data.The mathematical model of the soft gripper stiffness at different negative pressures was established and compared with the experimental data to verify the correctness of the theoretical model,and the results showed that the maximum load capacity of the soft gripper was increased by about 10 times and the stiffness of the soft gripper was increased by about 11 times at larger negative pressures.The variable stiffness soft body gripper designed in this paper can well improve the maximum load capacity and stiffness of the soft body gripper,which greatly improves the use range of the soft body gripper.