The effect of haptic interaction between balance assessment robot and pelvis on muscle activation of leg muscles.

Admittance control is considered as a promising paradigm in rehabilitation that provides us with means to establish well controlled and adjustable interaction and cooperation between rehabilitation devices and patients. Recently we developed balance assessment robot (BAR) for studying postural responses during walking as well as for pelvis manipulation during walking that implements admittance control as a mean of interaction with user. In this study we evaluated the characteristics of transparent haptic interaction and investigated whether transparent haptic interaction induces adaptations in muscle activation patterns with respect to free walking. In one neurologically intact individual we measured interaction forces, ground reaction forces and center of pressure as well as EMG of selected leg muscles while walking free and while walking with BAR. Results show that the amplitude of interaction forces in transparent mode of operation remained below levels that could have imposed considerable adjustments in muscle activation patterns of leg muscles.