Soft Robotic Fish

Over summer 2015, I worked in MIT’s Distributed Robotics Lab with Ph.D. candidate Robert Katzschmann building an autonomous soft-robotic fish. The purpose of the research was twofold: (1) to gain insight into the cyclic actuation of soft bodies and (2) to develop an autonomous device that can monitor fish without human interaction.

My main task was to redesign, build, and test hydraulic pumps that would increase swimming efficiency and decrease residual noise. I completed preliminary research on hydraulic pumps, designed and fabricated 3D models of various pumps, and tested the pumps’ performances. I evaluated pump performance by measuring flow rate, first tail flexion, and fish-like movement. My work culminated with a paper published to the 2016 International Conference on Intelligent Robots and Systems (IROS): “Cyclic Hydraulic Actuation of Soft Robotic Devices”

Hydraulic Pump Evaluation: The initial design was an external gear pump that could only flex the tail 6.5 degrees from a neutral position. I design several pumps and evaluated their performance. The most optimal pump was an external gear pump with large gears & maximized housing (high flow rate), minimal clearances (reduced backflow), and ceramic bearings (reduced friction). I designed the pump to be compatible with a brushed and brushless motor. I also coded speed controllers in C++ to optimize the pump performance while using an RC controller.

Results: Tail flexion greatly increased from 6.5 degrees to 13 degrees.