Hook, Line, and Tinker: Using robotic models to understand undulatory locomotion in fish

Abstract

Undulatory locomotion is complex and our ability to investigate aspects of this type of movement is limited in fish. Robotic models provide platforms for controlled experimentation and have become increasingly pop- ular tools for understanding aspects of form and function when experimentation with live animals proves too complicated. This thesis seeks to further our knowledge of interactions of critical parameters underlying the control and function of undulatory swimming using soft robotic models, and understand how robotic models have been used to further our knowledge of undulatory locomotion in general. First, in Chapter 1, I conduct an extensive survey of undulatory robotic models to ascertain both how robotic models are being used and contributing to our knowledge of undulatory locomotion in fishes as well as characterize any per- formance gaps that might exist between robotic models and the fish they are modeling. In Chapter 2, I use a soft robotic model called the duo-pneufish to investigate how interactive effects between frequency and stiffness affect thrust and lateral force generation. In Chapter 3 I summarize the findings of the duo-pneufish and present preliminary results from the quad-pneufish , the model presented in full in Chapter 4, as a invited chapter in a book discussing recent advancements in the field of underwater soft robotic systems. Lastly, in Chapter 4 I present the quad-pneufish and discuss the performance differences between realistic undulatory kinematics and novel swimming kinematics that are not observed in fish locomotion. Additionally, I focus on the effects of co-activation between left and right actuators and variable stiffness between anterior and posterior segments of the body on propulsive performance.