A comparison of the effects of majority vote and a decision-based velocity ramp on real-time pattern recognition control

Movement misclassifications often occur during real-time pattern recognition control. Majority vote and a decision-based velocity ramp are two different post-processing methods that have been suggested to improve real-time control. With majority vote, spurious misclassifications are removed at the expense of an additional controller delay. With a decision-based velocity ramp, the effect of misclassifications is minimized by attenuating movement speed following a change in decision from the classifier. The goal of the study was to determine which, if any, post-processing method improved real-time control above a baseline condition that did not involve post-processing. Five non-amputee subjects controlled a virtual prosthesis in real time using pattern recognition. While performing a challenging target achievement test in a virtual environment, subjects had significantly higher completion rates (p <; 0.04) and more direct paths to the target (p <; 0.02) while using the velocity ramp than while using majority vote or the control condition. There were no significant differences in completion rate or path efficiency between the majority vote conditions and the control condition (p >; 0.6). The benefits of removing misclassifications through majority vote may be offset by the added controller delay. These results highlight the need for real-time performance measures, as methods that have been shown to reduce errors during offline analysis may not improve real-time control.