Evaluation of command sources for a high tetraplegia neural prosthesis

One of the issues involved in the development of a neural prosthesis for high tetraplegia is that of an appropriate command interface between the user and prosthetic. With high levels of impairment come low levels of available voluntary actions suitable for issuing commands. Three potential command interfaces were investigated for their applicability to commanding endpoint position of a robot arm, as a proxy to a stimulated paralyzed arm. Head orientation as a command source was explored using both direct servo drive and gated ramp algorithms. EMG signals with a gated ramp algorithm from muscles in the face were also investigated as a potential command source. The information transfer rate (ITR) of all three command interfaces were evaluated using a 3D Fitts Law task. The resulting information transfer rate of the EMG interface was 0.55 Bits/sec, while both head orientation interfaces resulted in ITRs of 0.49 Bits/sec each.