Design criterion research and application based on grasping stability for shape self-adaptive ring gripper

Existing shape self-adaptive manipulators cannot meet the actual gripping requirements for large cylindrical objects. Furthermore, there are still some deficiencies in the design and research of shape self-adaptive manipulators for large cylindrical components. A shape self-adaptive ring gripper is proposed, incorporating a new underactuated grasping mechanism. Due to the influence of actual working condition and underactuated elements like springs, the grasping system can be easily disturbed by external disturbances. The study focused on the dynamic grasping stability of the gripper, investigating the relationship between design parameters of the spring and grasping stiffness. In this paper, the equivalent contact stiffness composed of spring stiffness and damping parameters is given. In order to analyse the dynamic gripping stability, the dynamic stability equations and Lyapunov energy function were developed. The results of the analysis demonstrate that the stability of an object with a known grasping configuration is dependent on the design parameters of the spring. A stability design criterion which contains the spring stiffness and damping parameters is deduced by giving an example. The dynamic grasping stability of the gripper is validated through simulation and experimentation. The gripper design presented in this paper is capable of achieving envelope-stable grasping of target objects.