Six-dimensional constraints and force feedback for robot-assisted teleoperated fracture reduction

Robots have the capability to perform precise and minimally invasive surgeries. For the robot-assisted teleoperated fracture reduction surgery, the operating accuracy largely depends on visual reference through fluoroscopy. The operator needs to adjust several times according to computed tomography (CT) image. During the robot reduction surgery, there are large muscle forces generated by the numerous muscles surrounding the fractured segments. However, there is no effective reduction force feedback to the master robot. In this paper, in order to improve the operating accuracy of the fracture reduction with teleoperated surgery mode, six-dimensional constraints of the master robot are studied by utilizing the virtual fixture method, which can restrict the position and orientation through the force and visual guidance. The six-dimensional force sensor is used to collect information of the reduction force. For the master robot, a motor stall control method based on the current loop is adopted to provide feedback of the reduction force, which can enhance the surgeon’s sense of operational presence. To verify the effectiveness of virtual fixture and force feedback, the fracture reduction experiments are conducted on the fractured model with simulating lager muscle force. Experimental results show that the reduction errors are within acceptable ranges: $0.03\pm 0.73\textrm{mm}$ , $0.54\pm 0.43\textrm{mm}$ , $0.46\pm 1.05\textrm{mm}$ , $1.05\pm 1.31^{\circ}$ , $1.15\pm 1.91^{\circ}$ , $1.09\pm 2.61^{\circ}$ . The number of fluoroscopy procedures required ranges from 1 to 2 and the average operation time is approximately 170 s. Compared to traditional methods and other teleoperation methods, the fracture reduction accuracy and surgical efficiency of method in this paper are significantly improved.