Abstract:
An 8 degrees of freedom (DOFs) robotic hand with parallel and self-adaptive (PASA) hybrid grasping modes is proposed to realize hybrid-mode underactuated grasping. Models of grasping postures and stability analysis are proposed to study the grasping performance of the PASA hand. Depending on the location, dimension and size of different objects, the PASA hand executes a parallel pinching (PA) mode for a precise grasp, a self-adaptive (SA) enveloping mode for a powerful grasp, or a PASA mode to imitate a human hand. The switch among different grasping modes is automatic and self-adaptive. Detailedly, the kinematics and the force distribution of the PASA hand are described, and also the grasping stabilities under different external forces are analyzed based on potential energy. Finally, different objects grasping experiments are conducted, while the contact forces are exactly measured in different states. Though the shapes and sizes of the objects are various, PASA hand can grasp tightly. Experimental results verify the reliability and the versatility of the PASA hand.