MMG-based multisensor data fusion for prosthesis control

Advantages in the functionality and comfort of soft silicon sockets or roll-on sleeves over polyester laminate hard sockets for upper-limb prosthesis have been consistently reported. However, attachment and wire breakage issues prevent the use of electromyography (EMG) sensors with soft sockets in electrically powered prosthesis for below-elbow amputees. Mechanomyography (MMG) is the measurement of the mechanical vibrations elicited by contracting muscles. The use of MMG sensors embedded within the soft silicon socket solves current attachment issues with EMG sensors and facilitates distal recording preventing wire breakage. In order to implement a practical MMG-based detection system of muscle contractions for prosthesis control, three silicon-embedded microphone-accelerometer sensor pairs were used to record MMG signals and movement artifact around the distal end of the residual limb of a below-elbow amputee. A multisensor data fusion strategy for the generation of binary control signals based on the root-mean-square (RMS) values of the segmented signals acquired with each transducer was trained and used as a detector. A ninety five (95%) and eighty six percent (86%) accuracy were achieved in the detection of contraction signals from the wrist extensors and flexors respectively. The error in the discrimination of movement artifact was thirteen percent (13%).