The effects of limb position and external load on offline myoelectric pattern recognition control

Limb position and load are factors that negatively affect myoelectric pattern recognition. While these effects have been studied separately, it remains unclear how limb position affects pattern recognition when limb load changes, and vice versa. Understanding this relationship will aid the development of algorithms and training protocols that allow prosthesis users to reliably grab and manipulate objects in various limb positions. We evaluated the effects of limb position and external load on offline pattern recognition accuracy in fourteen intact limb subjects and five below-elbow amputee subjects. Three clinically viable training methods were used to determine if training protocols can mitigate the negative effects of limb position and load. We found that limb position and load effects are independent in intact limb subjects, but are dependent in amputee subjects based on how the controller is trained. Although the advanced training protocols did not eliminate the limb position and load effects in most cases, they were able to reduce the effects and improve performance without increasing training time.