A Real Time Performance Assessment of Simultaneous Pattern Recognition Control for Multi-functional Upper Limb Prostheses

A natural and intuitive operation of multifunctional upper limb prostheses involves the concurrent activation of multiple degrees of freedom in a proportional way. Several approaches to simultaneous and proportional control strategies have been investigated; provided outcome measures however were offline accuracy or error rates and lacked the functional component of a preclinical assessment. This study evaluated a simultaneous proportional pattern recognition control strategy with two parallel classifiers in a two-dimensional Fitts' law style test and compared it to a sequential pattern recognition approach. The proposed test allowed for a complete evaluation through different performance metrics such as throughput (TP, bits/sec), path efficiency (PE, %), completion rate (%), overshoot (%) and reaction time (sec). We found that the simultaneous approach presented with numerous advantages with respect to the sequential alternative through significantly higher TP and PE for combined-motion targets (p<0.001) and significantly less overshooting in both combined and discrete targets (p<0.01). For discrete motions, the TP was significantly lower for the simultaneous approach (p