基于多点力约束的视网膜手术机器人的导纳控制

In retinal vein cannulation surgery, the surgical instrument needs to collide with the eyeball sclera incision and the target retinal vessel. In order to keep the tool-tissue forces at these two spots being within safety thresholds during the surgery, a robotic constrained control algorithm based on multipoint contact force is proposed. A robotic admittance controller was designed with the inputs of the contact forces between the surgical instrument shaft and the eyeball sclera (scleral force), and between the instrument tip and the retinal vessels (tip force). The admittance controller outputs the velocities of the instrument at the tip and at the sclera port in the robot coordinate system. The velocities of these two places are used to restrict the movement of the robot after being transformed into the same coordinate system. In the calculation of the velocities, a non-linear velocity trajectory planning method is proposed to achieve smooth changes of the velocity. The proposed constrained control algorithm was performed on a silicone eyeball model to simulate retinal injection experiments. The experimental results showed that in the presence of external disturbances, both the scleral force and the tip force are kept within given thresholds, which verified the effectiveness of multipoint force-constrained robot control algorithms in improving surgery safety.