A miniature bio-inspired locomotion mechanism for an intra-abdominal adhesion-reliant robot

This thesis presents, explains and analyses a novel design of a locomotion mechanism for a miniature robot envisaged for assisting surgeons during minimally invasive procedures in abdominal surgery. Minimally invasive procedures have proved to be beneficial for hospitals and patients and are currently applied successfully in many surgical operations. Robotic arms mounted outside the body are currently used in order to move the surgical tools inside the body and some research prototypes move fully inside the abdomen. In order to fully realise the potential of minimally invasive robotic surgery, the robotic assistant should operate at a distance from intense surgical activity and attach to tissue, moving stably within the abdomen. This thesis presents the conceptual design of a miniature robot which uses four adhesive pads to attach to the surface of the abdominal wall, a vantage point within the abdominal cavity. The adhesive pads use a micro-structured surface inspired by tree frogs in order to obtain smooth and repeatable attachment to biological tissue and enable the robot to move in inverted locomotion. The design of the locomotion mechanism of the robot also takes inspiration from tree frogs and geckoes in the way the pads are peeled off the tissue in order to detach them. Inspired by amoeboid locomotion, the robot detaches one pad at a time and changes the shape of the locomotion mechanism in the horizontal plane in order to move the pads across the tissue. The implementation and testing of the robot resulted in a proof-of-concept prototype, able to move consistently using magnetic pads with an adhesion force similar to the bio-mimetic pads. The robot also managed to attach and move the pads while attached to tissue with the bio-mimetic pads. The analysis of the locomotion mechanism resulted in the definition of a peeling model for the adhesive pad, and a stability criterion and control strategies for adhesion-reliant robots.