Human-robot-robot cooperative control using positioning robot and 1-DOF traction device for robot-assisted fracture reduction system.

While performing musculoskeletal long bone fracture reduction surgery, assistant surgeons can often suffer from physical fatigue as they provide resistance against the tension from surrounding muscles pulling on the patient's broken bones. These days, robotic systems are being actively developed to mitigate this physical workload by realigning and holding these fractured bones for surgeons. This has led to one consortium proposing the development of a robot-assisted fracture reduction system consisting of a 6-DOF positioning robot along with a 1-DOF traction device. With the introduction of the 1-DOF traction device, the positioning robot does not have to fight these contraction forces so can be compact improving its maneuverability and overall convenience; however, considering surgeon-robot interactions, this approach adds the requirement of controlling two different types of robots simultaneously. As such, an advanced cooperative control methodology is required to control the proposed bone fracture reduction robot system. In this paper, a human-robot-robot cooperative control (HRRCC) scheme is proposed for collaboration between the surgeon, the positioning robot, and the traction device. First, the mathematical background of this HRRCC scheme is provided. Next, we describe a series of experiments that show how the proposed scheme facilitates a reduction in the load placed on the positioning robot from strong muscular contraction forces making it possible to conduct fracture reduction procedures more safely despite the muscular forces.