Grasping Unknown Objects with Proprioception Using a Series-Elastic-Actuated Gripper

Grasping unknown objects has been an active research topic for decades. Approaches range from using various sensors to gain information about the object (e.g. vision, tactile, etc.) to building passively compliant hands that react appropriately to contact. In this paper, we focus on grasping unknown objects using proprioception (the combination of joint position and torque sensing). Our hypothesis is that proprioception can, by itself, be the basis for versatile performance, including multiple types of grasps for multiple object shapes and sizes, and transitions between grasps. We first introduce our hardware platform — a tendon-driven gripper using Series Elastic Actuation. We then propose a method for performing stable fingertip grasps for unknown objects, formulated as multi-input-multi-output (MIMO) control, and demonstrate its effectiveness experimentally. We also show that the proprioceptive gripper can perform enveloping grasps, as well as the transition from fingertip grasps to enveloping grasps.