Feasibility of controlling prosthetic hand using sonomyography signal in real time: preliminary study

The morphological changes of muscle can be accurately detected by sonography, a process we have termed sonomyography (SMG). This article investigates the feasibility of using muscle thickness deformation SMG as a new signal source to control a prosthetic hand in real time. Thickness deformation SMG of the extensor muscle was measured by a block-matching algorithm during wrist extension-flexion; the amplitude of the deformation was used to control the prosthetic hand. We compared various fast-search algorithms to select the best one for real-time prosthetic control. The two-dimensional logarithmic search (TDL) algorithm, with and without streaming single-instruction multiple-data extensions, showed excellent execution efficiency, with an overall mean correlation coefficient of about 0.99, a mean standard root-mean-square error <0.75, and a mean relative root-mean-square error <8.0% referenced to the cross-correlation algorithm baseline. The mean frame rates were greater than the ultrasound sampling rate (12 Hz), indicating that TDL could be implemented in real-time control. These results demonstrate that only one muscle position is needed to control a prosthetic hand, allowing for proprioception of muscle tension, and that the SMG provides good control of the prosthetic hand, allowing it to proportionally open and close with a fast-search algorithm.