There are over an estimated 100,000 upper extremity amputees currently living in the United States alone. Many of those people could benefit from the psychological gains and physical usefulness of a simple powered prosthesis. It is a sad fact that people who are viewed as different in our society stand out, but those people simply want to blend in and be treated normally, and be able to lead normal high functioning lives. Amputees are strong and capable people, who make do with what they have, and are able to overcome adversity. There is room for improvement in all aspects of current prosthetic technology relating to mechanical design, electrical signal processing, and overall system performance. There are not a large number of major companies developing competing products because the market is still quite small and limited from a business perspective. Shown in Figure 1 is an early prosthetic hook and socket created during the Civil War. Modern prosthetic hooks remain very similar aesthetically and it is time to move into the 21st century.
Figure 1 Civil War Prosthetic Hook (Cowan, 2012)
In fact, the artificial hands for prosthetics applications pose challenging specifications and problems, as is usually the case for devices to be used for functional replacement in clinical practice. These problems have forced the development of simple, robust, and reliable commercial prosthetic hands, as the Otto Brock Sensor Hand prosthesis which is widely implanted and appreciated by users. The Otto Bock hand has only one degree of freedom (DOF), it can move the fingers at proportional speed from 15-130 mm/s and can generates grip force up to 100 N.
According to analysis of the state of art, the main problems to be solved in order to improve the performance of prosthetic hands are
lack of sensory information gives to the amputee; lack of “natural” command interface; limited grasping
References: M.C. Carrozza, B. Massa, S. Micera, R. Larrarini, M. Zecca, P. Dario, “The Development of a Novel Prosthetic Hand - Ongoing Research and Preliminary Results”, IEEE Trans Mechatronics, vol. 7, pp. 108-1 14,2002. T. Lalibertt, C.M. Gosselio, “Simulation and design of underactuated mechanical hands”, Mech. Mach. Theory vol. 33, pp. 39-57 1998. R. S. Hirose, S. Ma, “Coupled tendon-driven muliijoint manipulator”, IEEE Conf. on Robolics and Automation, pp. 1268-1 275, 1999 B. Massa, S. Roccella, M. C. Carrozza, and P. Dario, “Design and development of an undemctualcd prosthetic hand”, IEEE Conf. on Robotics and Automation, vol. 4, pp. 3374-3379, 2002.