Design of a gearbox interface for robotic control of the SATA mechanism

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Abstract

Minimally invasive robotic surgery adds benefits to the patients, such as reduced blood loss, less scaring and reduced hospital stay. From the literature research preceding this thesis, some of the major obstacles in robotic surgery are the high costs and limited reusability of the instruments. In order to have more affordable robotic surgery, there is a need for low cost robotics and easily cleanable instruments. The design project presented in this thesis represents a driver interface for robotic control of the SATA instrument and is divided into three detachable subassemblies: a motor unit, a cup interface and a gearbox with angular position feedback. This project also represents an upgrade to an existing design that contains the motors and the gearbox inside a single unit, without any sensorics. Design requirements and goals were establish at the start of the project. Possible solutions were designed in CAD and mapped into a morphological table. Each design obstacle had many possible solutions that were considered before choosing the best suited ones. Two prototypes were build out of aluminium and steel with PEEK bushings and 3D printed outer cases. The range of motion and lateral pulling force of the SATA instrument controlled by these prototypes were tested, together with the assembly-disassembly times and shaft coupling times between the gearbox and motor unit shafts. The experimental results showed very low gearbox exchange times and low coupling times with learning curves that prove the ease of use for new users, all translating into a design that allows fast instrument exchange during surgery. The design requirements were met and physical prototypes built and tested, proving the concept works and is suited for the operating room, heading towards affordable robotic surgery.