Haptic noise cancellation: Restoring force perception in robotically-assisted beating heart surgery

Beating heart surgical methods have the potential to remove the need for the heart-lung machine and its attendant side effects, but must contend with the motion of the heart. Recent research in robotically-assisted surgery has produced a handheld, actuated instrument that can track and compensate for heart motion; however, the reaction forces caused by the actuation mechanism make it difficult for the surgeon to feel the heart during the operation, which can lead to unsafe tissue manipulation. This paper investigates an instrument design that negates reaction forces to the user by moving a counterweight out of phase with the moving mass of the actuator. The resulting instrument retains the tracking and motion compensation abilities of the current instrument, but reduces reaction forces felt by the user by over 80%. Subjects used the new instrument in an in vitro beating heart surgical contact task and performance was compared to the previously existing instrument. The new instrument provided a 28% increase in user force sensitivity and improved user reaction times by 51%, indicating that the new instrument greatly enhances force perception in beating heart tasks.