MINI JOYSTICK for Upper Limbs Prostheses A. Davalli (*) R. Sacchetti (**) (*) Area Delegate for the Research Dept. of the INAIL Prosthetic Center (Bologna ITALY) (**) Technical Director for the upper limb and auxiliaries line of the INAIL Prosthetic Center Introduction The use of myoelectric command is often difficult to apply to congenital pathologies of the upper limb, which alternative solutions such as pressure sensors or common microswitches are often used. In such cases, prosthesis command entails the use of the same techniques used with the myoelectric method, in other words, the activation of the various hand, wrist and elbow functions by means of a cyclic system or one based on subdividing the signal detected by the sensors into various levels. In movements involving more than one joint, only one function is activated at any one time, which, although extremely safe, often makes these operations lengthier and sometimes unnatural. Therefore using a mini-joystick for prosthesis control can prove extremely convenient as it permits combined control the functions of the artificial limb simultaneously according to the direction in which the joystick is moved. In today’s society, the possibility to access a PC is increasingly important for people with prostheses and the possibility of using the joystick to emulate a PC mouse becomes essential for patients, especially those with proximal pathologies, as using a traditional mouse with an artificial limb is problematic and awkward. This device permits the setting of two function modes: a) Prosthesis control mode b) Mouse emulation mode The two modes are mutually exclusive; the patient usually uses the joystick to control the prosthesis as described below; for use with a PC, the patient connects a cable to the prosthesis that will redirect the data from the mini-joystick to the PC rather than to the prosthesis. The decision to use a commercial component, on the one hand means having immediate access to a low-cost device with a PC compatible interface and that is therefore able to function directly as a mouse emulator and on the other, requires the implementation of a software interface integrated into the prosthesis control circuit that is able to receive information in mouse format. Various devices with different characteristics were analysed in order to choose the product that: • best exploits residual mobility in the remaining body segment; • supplies a sufficiently accurate output to be processed by the algorithm that controls the limb movement actuators. From “MEC '02 The Next Generation,” Proceedings of the 2002 MyoElectric Controls/Powered Prosthetics Symposium Fredericton, New Brunswick, Canada: August 21–23, 2002. Copyright University of New Brunswick. Distributed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License by UNB and the Institute of Biomedical Engineering, through a partnership with Duke University and the Open Prosthetics Project.