Structural Design and Puncture Control of Insertion Robot for FBG Embedded Cannula Flexible Needle.

Flexible needle has a sufficient pliability, which could steer clear of obstacles and correct the deviated path to achieve deep target insertions. It has a tendency of replacing rigid needles. An insertion robot for the flexible needle is one of the important parts of the robot-assisted surgery system. This paper proposed a novel insertion robot for an FBG (Fiber Bragg Grating) embedded cannula flexible needle and conducted puncture control experiments. The insertion robot consisted of a configuration adjustment mechanism and an insertion mechanism, which was compact and with a high insertion accuracy. The forward and inverse kinematics of the robot were calculated and the workspace was simulated using MATLAB/SIMULINK. The simulation results show that the robot has a workspace in size of about 200mm by 110mm by 140mm, which completely covers the required position and posture for the prostate insertion. Then a path tracking controller was designed to adjust the insertion path in real-time, realizing the tracking control of the planned path for the cannula flexible needle. Finally, the experiments were carried out to verify the rationality of the robot structure and the effectiveness of the puncture control in an environment with obstacles. The experimental results showed that the insertion average error was 1.3mm, the maximum error was 1.7mm, and the root mean square error was 0.3mm, fulfilling the insertion accuracy requirements of the clinical prostate surgery. This proved the rationality of the structural design and the high precision of the control.