A Bus Protocol for Intercomponent Communication in Advanced Upper-limb Prostheses

Many prosthetic devices today employ digital microcontrollers due to their great flexibility, but digital communication between individual devices is hardly exploited. A standardised digital intra-prosthetic communication channel may yield the following benefits that are demonstrated in conjunction with the introduction of “field ¬buses” in other industries: • Reduced wiring and thus a reduced fault rate. • Remote fault diagnosis and software upgrades. • Advanced control schemes, including coordinated multi-joint motion. • Modularity and interoperability and thus increased interchangeability of devices from different manufacturers. The latter point is clinically important because it simplifies the integration of hybrid systems and increases the freedom of choice of components. Furthermore, a common communication interface expands the possibilities for joint projects in advanced prosthesis control research. On this background a digital bus protocol is being designed, tailored especially for use in upper-limb prosthetics. The protocol allows flexible distributed joint control autonomously or coordinated by a central controller, based on a variety of user input signals such as EMG, switches, touch pads and more. The protocol will be incorporated in the NTNU Revolute Wrist Device, an experimental wrist prosthesis currently under development, as a basis for using it together with other experimental systems. On a longer term we plan to take initiatives to develop the protocol into an open standard with a set of device profiles and other elements that facilitate interoperability.