Hand-Impedance Measurements with Robots during Laparoscopy Training

This paper presents hand-impedance measurements during laparoscopic training with physically interactive manipulators. We develop a co-manipulated robotic system allowing hand-impedance measurements in an active manipulation task with occasional environmental contact. Six professional, four trainee surgeons, and ten novice subjects participated in our experimental program for a suturing activity where the novice subjects were involved in a five weeks training practice. Variable admittance controlled robots, attached to the tools with force sensors, applied step vice velocity disturbances while subjects were trying to set the needle perpendicular to the surgical driver. Hereby, impedances of the left and right hands were computed in four different directions. Then, the measured impedance parameters across all subjects were compared with respect to the participants’ level of proficiency and skill progression via statistical analyses to demonstrate effectiveness of the system. Results indicate that hand-impedance in the direction of the suturing-line demonstrates a consistent change throughout training and across different levels of expertise in laparoscopy. Therefore, hand-impedance information, proposed here, can pave the way for future development of robotic assessment or assistance in laparoscopy training programs.