This paper introduces a novel underactuated anthropomorphic gripper for prosthetic applications. In order to extend the grasping capabilities of underactuated prosthetic grippers and improve the force transmission ratio, a mechanical lever is mounted inside the palm that allows a proper distribution of the forces and provides mechanical advantage. A static model is developed and the possibilities offered by the lever transmission are investigated. Also, a compact mechanism is introduced to synchronize the motion of the four fingers. Additionally, a mechanical selector is designed that functions as a means of mechanically programming the motion of the fingers by selectively blocking their closing motion. Finally, a prototype, including all the above features, is described and experimental validation is briefly reported.

Providing contact sensing on the whole body of a robot is a key feature to increase the safety level of physical human-robot interaction. In this paper, a new robot skin capable of sensing multiple contact locations is presented. The motivation behind the proposed design is to produce a relatively inexpensive skin having the capability to provide the spatial location of collisions and also to add compliance to the robot's external cover. The resulting device is a thin flexible sensor sheet made of polyimide films with electrically conductive ink and a pressure sensitive conductive rubber sheet. The problem of internal wire routing is circumvented by the use of conductive ink and a circuit is proposed to minimize the number of output wires. To provide collision absorption and mechanical robustness, the sensor is embedded in different layers of polyurethane using shape deposition manufacturing (SDM). The paper presents the design and the fabrication process of the skin but also some experimental results on the determination of the mechanical properties of the resulting sensor as well as its potential for increasing human safety during human robot interaction.

No abstract

Abstract. This paper presents recent advances in the design of an underactuated hand for applications in prosthetics. First, the design of the fingers is addressed. Based on previous experiments with prototypes developed in the past, new tendon routings are proposed that lead to a more effective transmission of the forces. A novel elastic tendon routing is also proposed for the passive opening of the hand. A simplified static analysis of the fingers is proposed to support the results. Then, a new kinematic design of the thumb is presented. The thumb is designed to perform out-of-the-plane motions in order to broaden the variety of possible grasps. A mechanism for the implementation of underactuation between the fingers is proposed that alleviates the friction problems encountered in earlier hand designs. Finally, a prototype of the hand is briefly described and typical grasps are shown.

Considering the many advantages of underactuation in anthropomorphic hands, such as lightness, ease of control and compactness, it is of interest to develop mechanisms that aim at achieving underactuation between the fingers. This paper presents several tendon-driven underactuated mechanisms that can drive four outputs from one input. These mechanisms could typically be used to drive four fingers of an underactuated hand from a single input. Among these mechanisms, some are built by combining one-input/two-output differential mechanisms, while others are fully integrated systems of pulleys. For each mechanism, a static analysis is presented. Then, a discussion based on the static analysis and experimentation on models highlights their strengths and weaknesses. Finally a new anthropomorphic hand used as an experimental platform to test these mechanisms is introduced.