Description

We present a technical report, intended to serve as a step by step tutorial for the replication of the prosthetic hands. The guide contains illustrated instructions, carrying the user over all assembly steps and providing practical advice on any details that require attention.

Figure 1. Tools required to build all hand components.

Illustrations of all required parts (see for example Fig. 2 for a table of illustrated palm components), components, tools and materials (see Fig.1) are included, while comprehensive Parts Reference tables are provided (see for example a table containing all palm parts in Table 1).

Table 1. The parts required to assemble the palm.

Figure 2. Parts required to build the palm.

The assembly is divided into two main sections: 1) Fingers Assembly and 2) Hand assembly, with the latter containing instructions on how to build and attach all the hand components on the palm.

Figure 3. Attaching a flange on the assembled hand.

Hand Design

Following the design of the OpenBionics robotic hands [1], the Prosthetic hand [2] was designed to be affordable, lightweight and intrinsically-compliant. Its design is structurally and kinematically anthropomorphic. In particular, its sizing is parametrically determined by hand anthropometry studies [3], allowing for personalization and adjustment to the needs of each individual. Moreover, its kinematic model is derived by optimizing an index of anthropomorphism [4]. Finally, the prosthetic hand bears a novel differential mechanism based on the whiffletree mechanism [5] that allows the user to execute various grasping postures with a single actuator. Switching between the different postures or gestures is easy and intuitive. Simple locking buttons can independently block the motion of each finger. The proposed hands can be easily fabricated using low-cost, off-the-shelf materials and rapid prototyping techniques (e.g., 3D printing). The prosthetic hands assembly guide can be found here.

References

[1] A. Zisimatos, M. Liarokapis, C. Mavrogiannis and K. Kyriakopoulos, “Open-Source, Affordable, Light-Weight, Underactuated Robot Hands”, IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Chicago, IL, USA, 2014.

[2] G. Kontoudis, M. Liarokapis, A. Zisimatos, C. Mavrogiannis and K. Kyriakopoulos, “Open-Source, Anthropomorphic, Underactuated Robot Hands with a Selectively Lockable Differential Mechanism: Towards Affordable Prostheses”, IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Hamburg (Germany), 2015.

[3] B. Buchholz, T. J. Armstrong, and S. A. Goldstein, “Anthropometric data for describing the kinematics of the human hand,” Ergonomics, vol. 35, no. 3, pp. 261–273, 1992.

[4] M. Liarokapis, P. Artemiadis, and K. Kyriakopoulos, “Quantifying Anthropomorphism of Robot Hands,” in IEEE International Conference on Robotics and Automation (ICRA), vol., no., pp.2041-2046, 6-10 May 2013.

[5] L. Birglen and C.M. Gosselin, “Force analysis of connected differential mechanisms: application to grasping,” The International Journal of Robotics Research, vol. 25, no. 10, pp. 1033–1046, 2006.