In-Situ Force Augmentation Improves Surface Contact and Force Control

Surgeons routinely perform surgery with noisy, sub-threshold, or obscured visual and haptic feedback, either due to the necessary surgical approach, or because the systems on which they are operating are exceedingly delicate. Technological solutions incorporating haptic feedback augmentation have been proposed to address these difficulties, but the consequences for motor control have not been directly investigated and quantified. In this paper, we present two isometric force generation tasks performed with a hand-held robotic tool that provides in-situ augmentation of force sensation. An initial study indicated that magnification helps the operator maintain a desired supra-threshold target force in the absence of visual feedback. We further found that such force magnification reduces the mean and standard deviation of applied forces, and reduces the magnitude of power in the 4 to 7 Hz band corresponding to tremor. Specific benefits to stability, voluntary control, and tremor were observed in the pull direction, which has been previously identified as more dexterous compared to push.