Robotic endoscope system with compliance effect including adaptive impedance and velocity control for assistive laparoscopic surgery

Laparoscopic surgery becomes mainstream in minimally invasive surgery. This paper proposes a robotic endoscope system with compliance effect including adaptive impedance and velocity control to assist laparoscopic surgery. The system consists of stereoscopic head mount display (SHMD) and five degrees of freedom (D.O.F.) endoscope. SHMD includes Motion Node (gyro sensor) and force feedback device. Endoscope is equipped with tactile sensor and stereo vision on the tip. Surgeon only wears a light weight SHMD to control the endoscope by using head movement without additional assistant. Therefore, he can manipulate laparoscopy instruments simultaneously. Surgeon could press/release the pedal to enable/lock the tracking mode. The endoscope follows the pose of surgeon´s head in real time and the 3D image can be displayed on SHMD. Thus Surgeon can easily and safely perform laparoscopic surgery. The velocity of the endoscope movement is determined by adaptive impedance and velocity control which increases operation efficiency and keeps the compliance effect. The compliance effect provides a zero torque effect when the endoscope reaches target position. This effect is very helpful and safe for the laparoscope surgery. The impedance with the integral and derivative control design eliminates the steady state error and provides damping effect to reduce the influence of overshoot. The reaction torque observer reduces the ripple of torque and smoothes the output of velocity. In this paper, we implement the control algorithm and demonstrate the proof of concept to an one D.O.F. robotic endoscope in the horizontal plane. The experimental results show that we can control the endoscope easily and efficiently. In the future, we realize the new endoscope system and extend the algorithm to multi-joint control.