Page 443 - Biomedical Engineering and Design Handbook Volume 2, Applications

COMPUTER-INTEGRATED SURGERY AND MEDICAL ROBOTICS 421

Many microsurgical robots 70,124,131–133 are based on force-reflecting master-slave configurations.
This paradigm allows an operator to grasp the master manipulator and apply forces. Forces measured
on the master are scaled and reproduced at the slave and, if unobstructed, will cause the slave to
move accordingly. Likewise, forces encountered by the slave are scaled and reflected back to the
master. This configuration allows position commands from the master to result in a reduced motion
of the slave and for forces encountered by the slave to be amplified at the master.
While a force-reflecting master-slave microsurgical system provides the surgeon with increased
precision and enhanced perception, there are some drawbacks to such a design. The primary disad-
vantage is the complexity and cost associated with the requirement of providing two mechanical sys-
tems, one for the master and one for the slave. Another problem with telesurgery in general is that
the surgeon is not allowed to directly manipulate the instrument used for the microsurgical proce-
dure. While physical separation is necessary for systems designed to perform remote surgery, it is
not required during microsurgical procedures. In fact, surgeons are more likely to accept assistance
devices if they are still allowed to directly manipulate the instruments.
The performance augmentation approach pursued by the CIS group at Johns Hopkins University,
which has also been explored independently by Davies et al., 37–39 and which has some resemblances
to the work of Kazerooni, 134 emphasizes cooperative manipulation, in which the surgeon and robot
both hold the surgical tool. The robot senses forces exerted on the tool by the surgeon and moves to
comply. Our initial experiences with this mode in ROBODOC indicated that it was very popular with
surgeons and offered means to augment human performance while maximizing the surgeon’s natural
hand-eye coordination within a surgical task. Subsequently, we incorporated this mode into the
IBM/JHU LARS system. 26,36,49,135–139 Figure 14.23 shows one early experiment using LARS to
evacuate simulated hematomas with a neuroendoscopic instrument. 54,140–142 We found that the
surgeon took slightly longer (6 vs. 4 min) to perform the evacuation using the guiding, but evacu-
ated much less surplus material (1.5 percent excess vs. 15 percent).
More recently, we have been exploring the extension of these ideas into microsurgery and other
precise manipulation tasks. We have extended our model of cooperative control, which we call

FIGURE 14.23 Cooperative guiding using LARS for a neuroendoscopy
experiment. 54,140–142