Gravity Compensation of a Force/Torque Sensor for a Bone Fracture Reduction System

Recently, there have been efforts to develop bone fracture reduction robotic systems to relieve the surgeons’ physical load and X-ray exposure. In this paper, an interactive mode control scheme is proposed where a surgeon manipulates a positioning robot directly by applying force at a knob on a 6-axis Force/Torque (F/T) sensor attached on the positioning robot. The positioning robot supports and/or moves the distal fracture relative to the proximal fracture that is attached to the bed. However, F/T sensor noise, the knob’s gravity and the extra torque caused by the offset force deteriorate the robot’s maneuverability in the interactive mode control. In this work, the gravity force compensation method is introduced. This improved the maneuverability of an interactive mode control for the positioning robotic system.