Dexterity and Guidance Without Automation: Surgical Robot-Like Capabilities at a Fraction of the Cost
Lathrop, Ray Adams
:
2014-02-21
Abstract
This dissertation offers ways that the dexterity and guidance associated with image-guided
robotic surgery can be delivered without automation. The overall objective is to provide
highly capable instruments to surgeons, which can, in principle, be produced for a lower
overall cost or with greater overall capabilities than the robotic and image guidance systems
currently on the market. Of particular interest is creating a system for soft tissue
image guidance in a laparoscopic surgical setting, and designing laparoscopic tools that
can deliver dexterity similar to robotic surgical systems without the need for the robot.
Existing surgical registration systems for use in the abdominal cavity have used laser
triangulation or contact swabbing with a tracked probe to gather the point clouds of organ
surfaces. These point clouds are used to register the preoperative imaging to the work site.
This dissertation describes a new scanning system used to gather these point clouds which
is unlike prior systems because it requires no automation (indeed, it can be constructed
inexpensively from off-the-shelf components), is contactless, and can work through a laparoscopic
port. The system pairs a laser range finder with a standard optical tracking
system.
This dissertation then addresses the kinematic design of high dexterity tools with particular
attention to creating natural user interfaces. Since there exists no definition in the literature
for what constitutes a “natural” user interface for an articulated manual laparoscopic
tool, this dissertation puts forth a metric and a design guideline to design for “naturalness”
in this context. A user study is then used to explore the performance of several competing
instrument designs in the context of the metric and design guideline. Finally, the manner in which these results can inform surgical instrument design is illustrated in a description
of a prototype designed for throat surgery.
This dissertation then proceeds to consider natural user interfaces from an elastic energy
perspective. Under the assumption that a statically balanced mechanism that transparently
transfers user motion to instrument tip motion is most natural, this dissertation sets about
determining how energy storage elements used in laparoscopic “wrists” or “elbows” can
be statically balanced with additional elastic elements. Without static balance in these
mechanisms, the stored energy is felt by the user as a restorative force trying to return the
device to a neutral position. If the tool is required to have significant joint stiffness, the
restorative force felt by the user may be too high for practical surgical use. This section of
the dissertation culminates with the design of a novel, manual, laparoscopic prototype tool
with both wrist and elbow joints that features a statically balanced continuum joint.
The conclusion of this dissertation is that with appropriate mechanical design and sensor
choices it is possible to deliver many of the advantages promised by image-guided
robotic systems in manual devices. These devices can, in principle, be produced much less
expensively than robotic systems providing similar capabilities. This paves the way for a
future in which advanced surgical capabilities are delivered in a manner which places a
lower financial burden on the overall health care system.