Design of a variable-stiffness flapping mechanism for maximizing the thrust of a bio-inspired underwater robot

Compliance can increase the thrust generated by the fin of a bio-inspired underwater vehicle. To improve the performance of a compliant fin, the compliance should change with the operating conditions; a fin should become stiffer as the oscillating frequency increases. This paper presents a novel variable-stiffness flapping (VaSF) mechanism that can change its stiffness to maximize the thrust of a bio-inspired underwater robot. The mechanism is designed on the basis of an endoskeleton structure, composed of compliant and rigid segments alternately connected in series. To determine the attachment point of tendons, the anatomy of a dolphin's fluke is considered. Two tendons run through the mechanism to adjust the stiffness. The fluke becomes stiffer when the tendons are pulled to compress the structure. The thrust generated by a prototype mechanism is measured under different conditions to show that the thrust can be maximized by changing the stiffness. The thrust of the VaSF device can approximately triple at a certain frequency just by changing the stiffness. This VaSF mechanism can be used to improve the efficiency of a bio-inspired underwater robot that uses compliance.

[1]  Karl Iagnemma,et al.  A Novel Layer Jamming Mechanism With Tunable Stiffness Capability for Minimally Invasive Surgery , 2013, IEEE Transactions on Robotics.

[2]  Huosheng Hu,et al.  Biological inspiration: From carangiform fish to multi-joint robotic fish , 2010 .

[3]  Kyu-Jin Cho,et al.  Design and analysis of a stiffness adjustable structure using an endoskeleton , 2012 .

[4]  S. Kawamura,et al.  Development of passive elements with variable mechanical impedance for wearable robots , 2002, Proceedings 2002 IEEE International Conference on Robotics and Automation (Cat. No.02CH37292).

[5]  Kyu-Jin Cho,et al.  Design and Manufacturing a Bio-inspired Variable Stiffness Mechanism in a Robotic Dolphin , 2013, ICIRA.

[6]  T. Robinson,et al.  Minimally invasive surgery , 1999, European Surgical Research.

[7]  Chapman,et al.  Experimental simulation of the thrust phases of fast-start swimming of fish , 1997, The Journal of experimental biology.

[8]  R. W. Davis,et al.  Heterogeneity of myoglobin distribution in the locomotory muscles of five cetacean species. , 2001, The Journal of experimental biology.

[9]  Masataka Nakabayashi,et al.  Bioinspired Propulsion Mechanism in Fluid Using Fin with Dynamic Variable-Effective-Length Spring , 2006 .

[10]  K H Low,et al.  Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin , 2010, Bioinspiration & biomimetics.

[11]  R. Ham,et al.  Compliant actuator designs , 2009, IEEE Robotics & Automation Magazine.

[12]  M. Jafari,et al.  Modelling and Parametric Study of Gas Turbine Combustion Chamber , 2012 .

[13]  Sadao Kawamura,et al.  Haptic displays implemented by controllable passive elements , 2002, Proceedings 2002 IEEE International Conference on Robotics and Automation (Cat. No.02CH37292).

[14]  Rolf Pfeifer,et al.  Varying body stiffness for aquatic locomotion , 2011, 2011 IEEE International Conference on Robotics and Automation.

[15]  Hirohisa Morikawa,et al.  Structure and Bending Properties of Central Part of Tail Fin of Dolphin , 2010 .

[16]  Yonghui Hu,et al.  Optimized design and implementation of biomimetic robotic dolphin , 2005, 2005 IEEE International Conference on Robotics and Biomimetics - ROBIO.

[17]  Karl Iagnemma,et al.  Design and Analysis of a Robust, Low-cost, Highly Articulated manipulator enabled by jamming of granular media , 2012, 2012 IEEE International Conference on Robotics and Automation.

[18]  Maarja Kruusmaa,et al.  A bio-mimetic design and control of a fish-like robot using compliant structures , 2011, 2011 15th International Conference on Advanced Robotics (ICAR).

[19]  Pao Tai Lin,et al.  Mid-infrared materials and devices on a Si platform for optical sensing , 2014, Science and technology of advanced materials.

[20]  Stanley H. Cohen,et al.  Design and Analysis , 2010 .

[21]  Kyu-Jin Cho,et al.  The effect of compliant joint and caudal fin in thrust generation for robotic fish , 2010, 2010 3rd IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics.

[22]  C. A. Pell,et al.  Mechanical control of swimming speed: stiffness and axial wave form in undulating fish models , 1995, The Journal of experimental biology.

[23]  G. Hirzinger,et al.  A new variable stiffness design: Matching requirements of the next robot generation , 2008, 2008 IEEE International Conference on Robotics and Automation.

[24]  H. Bart-Smith,et al.  Central Pattern Generator Control of a Tensegrity Swimmer , 2013, IEEE/ASME Transactions on Mechatronics.

[25]  Y. Imaizumi,et al.  Propulsion system with flexible/rigid oscillating fin , 1995 .

[26]  K. H. Low,et al.  Modelling and parametric study of modular undulating fin rays for fish robots , 2009 .

[27]  Ravi Janardan,et al.  Design and manufacturing , 1997 .

[28]  David Scott Barrett,et al.  Propulsive efficiency of a flexible hull underwater vehicle , 1996 .

[29]  M. Kruusmaa,et al.  A flexible fin with bio-inspired stiffness profile and geometry , 2011 .

[30]  Kyu-Jin Cho,et al.  Kinematic Condition for Maximizing the Thrust of a Robotic Fish Using a Compliant Caudal Fin , 2012, IEEE Transactions on Robotics.