An Investigation of Undulating Shape Adaptation Characteristics of a Hydraulic-Driven Bionic Undulating Robot

Abstract

Fish Swimming in MPF (Media and/or Paired Fin) mode has unique hydrodynamic characters and special application in resource exploration underwater. Inspired of the flexible shape and motion of undulating fin of “Nilotic Ghost” fish, a Hydraulic-driven Bionic Undulating Robot (HBUR) is developed and studied in the paper based on CFD method, to investigate the flexible characteristics of shape adaptation and hydrodynamics of HBUR fin, which has great significance for the propelling safety of HBUR underwater. In this paper, a mathematical model is brought forward to indicate the undulating motion of HBUR, which is formed by sequentially and periodically swing motions of Hydraulic Swing Actors (HSAs), and then the CFD method is introduced to calculate the hydro-forces when undulating shape of HBUR fin are distorted, because of distraction underwater. Results show that HBUR could produce propelling forces even when some of the HSAs are restricted from swinging, and shape adaptation ability of different part on HBUR fin is different, where the middle part is worse than the two sides. The propelling forces generated by undulating motion the rest of HBUR fin could be used to get the underwater robot out of trouble itself, and then undulating shape will restore to normal state.