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fixation of the pivoting point at the trocar port. For the inserting motion of the forceps, we adopted "double-stage
mechanism" inspired by ladder truck. It realized double-long working distance comparing with the length of lin-
ear stage. Wire-driven bending forceps with two DOFs had wider working space than human hand, thus motion
space was enough to follow surgical procedures. Tendon-driven bending forceps had two independent joints that
realized easy control and stable motion. We also implemented separation mechanism tor sterilization considering
the clinical application. The separation mechanism showed another benefit in the bending forceps; we could easily
exchange the various instruments (Figure 4) depending on the surgical scenario by just connecting instruments to
the motor driving unit. Slave manipulator was built by integrating those modules. As the results of evaluations and
in-vivo experiments, our new robot was feasible as a slave robot in the master-slave surgical robot system for
laparoscopic surgery. As future works, we will also integrate an electric cautery forceps and a laser coagulator as
end effectors on this robotic system. They will work as novel therapeutic devices different from conventional sur-
gical robot just following the surgeon's hand motion.
This study was supported by the Research for the Future Program JSPSRFTF99I00904.

TABLE 1
EVALUATION RESULTS OF FORCEPS MAN1PUTLATOR

working range max. speed (25/1000[msec]) torque or force
RCM Rotationl 171.27±0.05[deg] 216[deg/sec] 230[deg/sec] 3.6[Nm]
Mechanism Rotation2 62.52 ±0.12[deg] 91[deg/sec] 93[deg/sec] 3.6[Nm]
Insertion 287.30 ±0.06[mm] 120[mm/sec] 160[mm/sec] 5.5[N]
Forceps
Rotation 356.55 ±0.13[deg] 7.5 [round/sec] 17.5[round/sec] 0.48[Nm]

TABLE2
EVALUATION RESULTS OF BENDING FORCEPS

working range[deg] accuracy[deg] backlash[deg] max.speed[deg/sec Torque[mNm]
Bendingl(+) +147.7 -3.7 + 0.7 14.6 + 0.1 161 16.0
Bending l(-) -156.2 -3.6 + 0.9 14.6 + 0.1 161 16.0
Bending2(Jawl) +96.3 -5.8 ± 0.5 16.4 + 0.4 120 31.5
Bending2(Jaw2) -104.3 -4.3 ± 0.8 20.1 ±0.3 120 40.7

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