Dexterity and Guidance Without Automation: Surgical Robot-Like Capabilities at a Fraction of the Cost
Lathrop, Ray Adams
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.