DESIGN APPLICATIONS

by David J. Bak
Senior Regional Technical Editor

Troy, NC--Most control systems for prosthetic hands offer simple on/off operation, with no variable speed or grip ability. They are generally bulky, heavy, and limited to a single prosthesis type and size. Finally, such control systems provide no diagnostic tools to evaluate prosthesis performance or use.

Michael Tompkins of Animated Prosthetics wants to change this situation. Employing recent advances in electronics and battery chemistry, his company has created an intelligent prosthesis control system. The design interfaces with all currently available, externally powered child and adult hands, as well as any analog or digital patient sensing device.

Two parts make the complete system: The Animation Control System (ACS), which installs in the prosthesis, and a remote Prosthesis Configuration Unit (PCU). The PCU communicates with the ACS via radio transceiver; both are microcomputer controlled.

Powered by small, lightweight, lithium-ion/lithium-polymer batteries, the ACS easily fits inside any prosthesis, eliminating external battery pack or cables. All algorithms for battery charging are in the ACS itself, and the unit continually monitors battery operation to protect from over-voltage, over-charge, under-voltage, and over-discharge.

Selectable operation styles called TASCs (Techniques, Algorithms, and Strategies of Control) allow multiple methods of hand operation. These range from on/off to variable speed/grip. The ACS will also operate a second device such as a wrist rotator using the same patient sensors.

As a patient's ability improves, the TASC can be changed accordingly. Information regarding prosthesis use, logged in by the ACS microcomputer, can be retrieved by the PCU. The prosthetist has the ability to monitor a patient's signals and select the best control TASC--even if the patient cannot communicate directly.

Both Animation Control System and Prosthesis Configuration Unit are presently undergoing clinical testing at Duke University Medical Center, Durham, NC.

Additional details…Contact Michael Tompkins, Animated Prosthetics, Inc., Box 805, Troy, NC 27371, (910) 576-5023