Study On Grasping Performance Of Variable Stiffness Flexible Gripper Based On Line Drive And Particle Interference

For fragile/damaged or explosive targets,the flexible gripper can only non-destructively grab some light-weight targets,and it is difficult to achieve non-destructive grabbing of multiple types of targets.The variable stiffness flexible gripper has the operability of the flexible system,soft contact and the stability and strength of the rigid system,and is a research hotspot in the field of non-destructive grasping.At present,the flexible gripper with variable stiffness has the problems of poor bending ability,small adjustment range of stiffness and weak grasping ability.In this paper,a flexible gripper with variable stiffness based on line actuation and particle interference is proposed,and the forward kinematics and variable stiffness contact mechanics of the gripper are analyzed.It can realize the functions of greatly improved grasping force,controllable grasping force,adjustable stiffness and stable grasping,and provide theoretical guidance and technical support for the development of non-destructive grasping technology for fragile/damaged or explosive objects.The main research contents of this paper are as follows:(1)By analyzing the driving method and principle of the flexible gripper with variable stiffness,a combined driving method of wire-driven bending deformation and negative pressure particle interference variable stiffness is proposed,and the bending gripping action and stiffness adjustment function are controlled by driving the pulling wire and negative pressure separately.3D printing technology is used to complete the manufacture of key parts,and a flexible gripper with variable stiffness based on wire actuation and particle interference is designed.(2)Based on the piecewise constant curvature Denavit-Hartenberg(D-H)parameter method,the positive motion model of the flexible gripper with variable stiffness was established,and the motion analysis of the flexible gripper with variable stiffness was carried out.The trajectory of the fingertips.Using the Hertzian contact theory model,the contact force analysis between the particles and the jacket film under negative pressure was carried out,and the variable stiffness mechanical model with the main parameters such as negative pressure value,particle radius,winding rate,elastic modulus and Poisson’s ratio was established.(3)Build an experimental platform for the flexible gripper with variable stiffness to study the effects of the gripper’s external dimensions,filling particles,winding rate and negative pressure on its bending performance and stiffness adjustment ability,and develop the maximum grasping of the flexible gripper with variable stiffness.Force test experiment.Through non-destructive grasping experiments on objects of various shapes,sizes and weights,the grasping ability of the variable stiffness flexible gripper on the ground and underwater is verified.The experimental results show that the maximum bending angle of the gripper is±180°,the error compared with the theoretical analysis results is less than 6.7%,the stiffness can be increased by more than 15 times under negative pressure,and the maximum grasping force of the gripper is 56.8N.