The Research Of Variable Stiffness Gripper Based On Differential Drive Particle Jamming

Compared with the traditional rigid grippers,the soft gripper made of flexible materials have good adaptability and safety,which have broad application prospects in the fields of medical treatment,rescue,detection and industrial production.At this stage,because the soft robots is a new research field,the researches of soft grippers are still in the exploratory stage.Although the soft grippers proposed by researchers show good adaptability and flexibility,its general stiffness is small and its carrying capacity is weak.Therefore,this subject takes the variable stiffness soft gripper as the research object.Aiming at the variable stiffness mechanism,structure design,fabrication method and theoretical model of the soft gripper,a differential drive variable stiffness soft gripper based on particle jamming is proposed.(1)By studying common driving modes and variable stiffness mechanism of soft robots particle jamming is used to adjust the stiffness of soft grippers in this study.The soft gripper proposed in this study consists of three identical soft actuators.Through the special structure design,the soft actuators are designed as a double-chamber structure based on the mechanism of fiber reinforcement.One chamber is an air chamber,which mainly controls the bending of the actuator.The other chamber is filled with particles.The two chambers are separated by an elastic film.The air pressure in two chambers can be controlled independently,and the particle jamming degree in the actuator can be adjusted by controlling the pressure difference between two chambers,so as to realize the dynamic adjustment of the stiffness of the soft gripper.(2)The deformation characteristics of flexible materials and soft actuators under fiber reinforced structures are analyzed.The deformation characteristics of flexible materials and soft actuators under fiber reinforced structures are analyzed.Based on the twochamber structure and special control mode of the soft actuators proposed in this study,a mathematical model describing the bending and stiffness characteristics of a single soft actuator driven by air pressure is established.It provides a theoretical basis for predicting and controlling the deformation and stiffness of the soft actuators.(3)We built an experimental platform to test the performance of the software gripper.By grasping objects of different size and shape,the good adaptability and safety of the soft gripper proposed in this study for grasping irregular objects are verified.Through the load-bearing capacity experiment of the soft gripper,it is verified that the soft gripper proposed in this study has good stiffness adjustment ability.The validity of the mathematical model describing the bending characteristics and stiffness change characteristics of a single soft actuator is verified by the stiffness and bending angle experiments.The effects of driving pressure,structural parameters and filled particle types on the stiffness of the drive are analyzed respectively.By testing the stiffness and bending angle of different soft actuators,it is verified that the soft actuators proposed in this study can maintain flexible deformation and have a larger range of stiffness adjustment.