[Study on Trajectory Tracking Control of a Flexibly-Driven Fracture Reduction Robot]

To reduce the risk of iatrogenic soft tissue injury and collision between fracture fragments, while maintaining a satisfactory reduction state to perform procedures such as intramedullary nail internal fixation, research on trajectory tracking control for fracture reduction robots was conducted.

Firstly, considering the driving characteristics of the fracture reduction robot, a sliding mode variable structure controller was designed for the traction mechanism responsible for performing axial traction along the femur. For the rotation mechanism responsible for performing circumferential rotation around the femur and anteroposterior-lateral reduction of fracture fragments, a joint adaptive fuzzy PID controller was designed. Secondly, to ensure a smooth and shock-free reduction process, a quintic non-uniform B-spline curve was employed for reset trajectory planning of the robot. Finally, reduction simulation experiments were conducted on the robot under the same conditions of muscle contraction force and external disturbances.

After reduction, the maximum angular error was less than 2°, and the maximum translation residual was 2.3 mm, and the reduction accuracy met the clinical functional reduction criteria. When the robot was maintaining the reduction state and an interference signal was manually applied to the distal end of the fracture, the system recovered the lost reduction state and stabilized at the target value within 3.6 s.

The experimental results confirm the flexibility and robustness of the robotic control system, which has a promising application prospect.