A Parallel Gripper with a Universal Fingertip Device Using Optical Sensing and Jamming Transition for Maintaining Stable Grasps For a robotic gripper to perform as well as the human hand, the performance of the tactile sensing and grasping of the gripper must be improved. In this study, a parallel gripper with a universal fingertip device that combines both object holding using jamming transition and optical sensing is proposed. By using a transparent material along with the jamming transition, both a tactile sense is achieved via optical sensing and the holding stability is improved by tightly restraining the object. Because the hardness of the contact region of the membrane can be adjusted, the gripper can grasp heavy objects as well as light objects. In this paper, the structure of the developed gripper and its grasping characteristics are described, and the experimental results from grasping and sensing are presented. It is experimentally shown that the proposed gripper is capable of both grasping fragile objects (such as an egg and tofu) by using tactile sensing and grasping dumbbells (with weights between 13 kg) by using jamming transition. Additionally, grasping a plastic cup, the proposed gripper demonstrated the potential of combining tactile sensing and moreconstrained grasping.

Development of New Extensible Components for Enabling a More Flexible Usage of JammingGripper In many applications, gripping systems are key elements to turn industrial robots into flexible and versatile handling systems. Depending on the gripping principle those systems can either be rather limited or very flexible in terms of gripping a broad variety of different objects. The socalled jamminggripper can grasp a wide range of objects by passively adapting to the shape of different workpieces. The purpose of the work described in this paper is to develop extensible components for optimizing the jamminggripper. Concerning the previous jamminggripper, the problems related to a mechanical structure, installing a filter, a balloon as a membrane, and filling the balloon with powder are investigated to improve the jamminggripper system. A new gripper system designed is presented to not only address the existing problems but also to make it even more userfriendly and practical. Tests are performed to determine the influence of three different filling ratios of the membrane on the gripping performance for objects with complex geometries.