The focus of this research is in developing autonomous underwater vehicles that are inspired by the efficiency and propulsion of fish and other aquatic animals. For example, we developed an artificial fish  using flexible matrix composite actuator technology. This innovative approach to fin actuation uses structurally integrated and distributed actuators to avoid the losses associated with conventional means of driving bioinspired propulsors, and more closely match the exceptional performance of natural swimmers.

It was demonstrated that a nearly constant thrust with almost zero oscillation magnitudes can be obtained by tuning the oscillation frequency with the fish body elasticity.  As shown below, the oscillations in the thrust at 1 Hz flapping frequency essentially disappear, leaving a constant thrust.  Above 1 Hz, the oscillations in thrust reappear.  This hydroelastic tuning of the fish tail with the actuation frequency provides valuable insight into biology where it is believed that fish regulate the stiffness of their muscular system for increasing efficiency and thrust.

Fish Thrust at 1 Hz
fishfem
fishswim
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Some example publications from this work:

  • Zhang, Z., Philen, M., Neu, W., "A biologically inspired artificial fish using flexible matrix composite actuators: analysis and experiment," Smart Materials and Structures, Vol. 19, No. 9, pp. 1-11, 2010.
  • Philen, M., Neu, W., “Hydrodynamic analysis, performance assessment, and actuator design of a flexible tail propulsor in an artificial alligator,” Smart Materials and Structures, Vol. 20, No. 9, 2011.
  • Philen, M., “Plant-Inspired Flexible Matrix Composite Actuators for Biomimetic Underwater Propulsion Systems”, Plants and Mechanical Motion— A Synthetic Approach to Nastic Materials and Structures, Editors: Janet Sater and Normal Wereley, 2012.
  • Philen, M., Neu, W., “Performance Assessment and Actuator Design of a Flexible Tail Propulsor in an Artificial Alligator,” ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, September 28- October 1, Philadelphia, PA, 2010.
  • Zhang, Z., Philen, M., Neu, W., “Development of a Bio-Inspired Artificial Fish using Flexible Matrix Composite Actuators,” ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, September 21-23, 2009.