Design and development of multi-arm robots for single-port access surgery - Exploring the miniaturisation potential of fluidic actuation

Surgical procedures are a staple of our healthcare system. While early traces of surgery date back as early as 3000 B.C., technology has revolutionised surgery in the past 50 years. More and more procedures are possible while procedures become less and less invasive, reducing patient trauma and accelerating recovery. In the current age, Single-Port Access (SPA) surgery offers further reductions in invasiveness thanks to a single, small incision to insert long and thin instruments. However, where multi-port laparoscopic interventions are already difficult to perform due to a reduced and decoupled 2D vision, the loss of degrees of freedom, occasional tremor amplification due to long instruments and the fulcrum effect, SPA surgery is even more challenging. Collisions between instruments, obstruction between multiple clinicians operating next to the single port, poor triangulation of the operating site and a further loss of intuitive motion hamper SPA clinical adoption. Robotic assistance is regarded as having the potential to address the above-mentioned issues. This thesis aims at contributing to the emergence of novel surgical robotic platforms by investigating the potential of fluidic actuation to create smaller and modular approaches to surgery. Challenges for robot-assisted MIS are very different depending on whether one works in a confined and narrow space, such as transoral surgery or in a shallow and wide space, such as abdominal laparoscopy. One surgical procedure belonging to each category is selected to confront fluidic actuation to the whole spectrum of challenges inherent to surgical robots. The first part of this thesis investigates transoral robotic surgery. The study, design and prototyping of a novel controllable add-on CO2 laser fibre carrier, compatible with da Vinci Endowrist instruments, is described. The instrument is conceived in tight collaboration with Ear-Nose-Throat surgeons. The design is prototyped, tested and reviewed with the surgeons several times before reaching satisfactory maturity. A successful pre-clinical cadaveric study is conducted as the final validation of this development. The second part of this thesis investigates foetal surgery and more specifically Open Spina Bifida repair. A novel multi-arm robot for single-port access surgery is developed. The design of the complete surgical robot can be divided into five steps. First, The design requirements and potential solutions are presented in detail. Based on these, a macro-micro concept is adopted. It consists of a macro concentric tube robot triangulation platform and a micro distal bending segment. A first prototype is built and characterised, proving that the macro-micro approach offers a stable triangulation platform and a dynamic and precise end-effector. Second, the stiffness of the macro-micro platform is optimised using laser-cut patterns for the high-force tasks required for Open Spina Bifida repair. Third, specific instrumentation for continuum robots is developed. A hybrid gripper and needle-driver is designed. Combining form and force closure properties, the gripper can securely hold a suture needle with low input forces. Fourth, two continuous robot kinematic models are derived for both the macro triangulation platform and the micro distal bending end-effector. The micro kinematic model considers the influence of both the bending and the gripping cables. Finally, a compact drive unit that can provide high force and high stiffness is designed and prototyped iteratively. A key feature of this drive unit is a non-permanent clamping mechanism that allows driving two parallel tubes in close proximity; using actuators with limited stroke. This non-permanent clamping mechanism also allows exchanging instruments within one minute, providing great modularity. The whole system is finally validated by performing running sutures on a skin phantom using a bi-manual teleoperation setup. This thesis developed two novel surgical systems with dramatically different sets of constraints and using mainly fluidic actuators. The performance of these systems proves that fluidic actuation, while not being a 'one size fits all' solution, possesses great potential for the miniaturisation of surgical robots. The contributions achieved while developing these two robotic platforms mark important steps towards the next generation of surgical robots. By bringing more and more possibilities into the hands of surgeons, more and better treatment opportunities can reach those in need. Suggestions on the remaining work needed to bring these platforms to the operating theatre are provided at the end of this thesis.

Publication year:2023

Accessibility:Open