At the press of a key, the instrument's patent-pending action moves the respective string toward a rotating, rosin-edged wheel spinning inside the barrel of the Wheelharp, where it's essentially bowed by the wheel. The mechanism is claimed capable of translating the player's subtle fingerings into a range of bowing intensities.

At the press of a key, the instrument's patent-pending action moves the respective string toward a rotating, rosin-edged wheel spinning inside the barrel of the Wheelharp, where it's essentially bowed by the wheel. The mechanism is claimed capable of translating the player's subtle fingerings into a range of bowing intensities.
http://www.gizmag.com/antiquity-music-jon-jones-wheelharp-namm-debut/26000/