Design and experimental evaluation of a sensorized parallel gripper with optical mirroring mechanism

This work presents the design, prototyping, and experimental evaluation of a parallel gripper with an optical mirroring mechanism based on the Periscope principle to enable vision-based sensing. The mechanism incorporates an optic system of three mirrors and a convex lens to transfer the grasping activity from the fingertip to a stationary camera placed at the gripper base. The mechanism arrangement allows isolating the camera from the grasping workspace to ensure its safety. The gripper prototype is equipped with a neuromorphic event-based camera that observes the reflected images from the optical mirroring mechanism to detect high-speed phenomena, such as object slippage. Experimental evaluation is carried out to assess the grasping and sensing capabilities of the gripper in a slip detection task. The results indicate that the event-based camera can detect slip moments across a different set of objects that represent surface, line, and point contact cases at a speed of 500 μs (i.e., 2 kHz) through a feature-based slip detection algorithm, highlighting the success of the proposed mechanism in providing a clear transmission of the grasping activity to the camera and enabling the sensorization of the gripper.