Abstract

The rectilinear motion of a capsule can be generated using a periodically driven internal mass interacting with the main body of the capsule as a ‘hammer’ in the presence of external resistances. At resonance, this ‘hammer’ enables the capsule to progress efficiently through complex environments without the need for external accessories. This simplicity in mechanical design and control significantly reduces complications associated with traditional external propellers or fins. However, as a non-smooth system experiencing vibrations, frictions, and impacts, the capsule exhibits a rich variety of behaviours known as multistability, where different long-term behaviours co-exist for a given set of parameters. This can pose significant control challenges when specific attractors dominate the dynamics inside the gut. This talk will discuss our journey from mathematical modelling and numerical analysis to optimisation, control, experimental validation, and ex vivo testing. I will focus on the non-smooth dynamics of the system and the fine-tuning of its parameters to optimise progression rate and force generation, presenting both numerical and experimental results to demonstrate its feasibility in lower gastrointestinal endoscopies.