Laparoscopic surgery is minimally invasive surgery (MIS), a new kind of surgery that gets more and more common nowadays. In this method, a surgical operation is performed by the help of laparoscope and several long, thin, rigid instruments through small incisions. In recent years, laparoscope manipulator that substitutes a camera assistant in surgical operations, is used more widely in laparoscopic surgery. But it is a bothersome task for surgeon to control laparoscope manipulator manually or with his voice.
In this paper, a new real-time visual servoing unit for laparoscopic surgery is presented. This unit can automatically control laparoscope manipulator through visual tracking of laparoscopic surgical tool. Therefore the unit is composed of two parts. One is visual tracking part and the other is manipulator controlling part.
To track the instrument robustly in real-time, two-stage adaptive Condensation (Conditional Density Propagation) algorithm has been proposed. The proposed algorithm is based on the Condensation algorithm which is known as the visual tracking method using stochastic propagation of conditional density. The proposed algorithm utilizes color features as measures of the Condensation algorithm, that help the algorithm realize real-time visual tracking. To find out tip position of the surgical tool obviously in possible surgical environment, the algorithm update the color feature of surgical tool and then apply the Condensation tracker in two-stage To control laparoscope manipulator safely and stably, intelligent control method has been applied. This method utilizes virtual damper system in controlling the manipulator. The virtual damper system can play the parts of safety device and real damper in surgery. So the motion of manipulator is limited in safe region of surgery and achieved stably.
Finally, to verify the visual servoing unit, a conventional laparoscope manipulator AESOP has been utilized. The experimental results show that the proposed visual tracking algorithm is highly robust and the controlled manipulator can present stable view with safe.
