Details

Borrowing from Mother Nature, a team of MIT researchers has built a school of swimming robo-fish that slip through the water just as gracefully as the real thing, if not quite as fast.

Mechanical engineers Kamal Youcef-Toumi and Pablo Valdivia Y Alvarado have designed the sleek robotic fish to more easily maneuver into areas where traditional underwater autonomous vehicles can't go. Fleets of the new robots could be used to inspect submerged structures such as boats and oil and gas pipes; patrol ports, lakes and rivers; and help detect environmental pollutants.

"Given the (robotic) fish's robustness, it would be ideal as a long-term sensing and exploration unit. Several of these could be deployed, and even if only a small percentage make it back there wouldn't be a terrible capital loss due to their low cost," says Valdivia Y Alvarado, a recent MIT PhD recipient in mechanical engineering.

Robotic fish are not new: In 1994, MIT ocean engineers demonstrated Robotuna, a four-foot-long robotic fish. But while Robotuna had 2,843 parts controlled by six motors, the new robotic fish, each less than a foot long, are powered by a single motor and are made of fewer than 10 individual components, including a flexible, compliant body that houses all components and protects them from the environment. The motor, placed in the fish's midsection, initiates a wave that travels along the fish's flexible body, propelling it forward.

The robofish bodies are continuous (i.e., not divided into different segments), flexible and made from soft polymers. This makes them more maneuverable and better able to mimic the swimming motion of real fish, which propel themselves by contracting muscles on either side of their bodies, generating a wave that travels from head to tail.

"Most swimming techniques can be copied by exploiting natural vibrations of soft structures," says Valdivia Y Alvarado.

As part of his doctoral thesis, Valdivia Y Alvarado created a model to calculate the optimal material properties distributions along the robot's body to create a fish with the desired speed and swimming motion. The model, which the researchers initially proposed in the journal Dynamic Systems Measurements and Control (ASME), also takes into account the robot's mass and volume. A more detailed model is described in Valdivia Y Alvarado's thesis and will soon be published along with new applications by the group.

Other researchers, including a team at the University of Essex, have developed new generations of robotic fish using traditional assembly of rigid components to replicate the motions of fish, but the MIT team is the only one using controlled vibrations of flexible bodies to mimic biological locomotion.

"With these polymers, you can specify stiffness in different sections, rather than building a robot with discrete sections," says Youcef-Toumi. "This philosophy can be used for more than just fish" - for example, in robotic prosthetic limbs.

Mimicking fish:

With motors in their bellies and power cords trailing as they swim, the robo-fish might not be mistaken for the real thing, but they do a pretty good fish impersonation.

The team's first prototypes, about five inches long, mimic the carangiform swimming technique used by bass and trout. Most of the movement takes place in the tail end of the body. Fish that use this type of motion are generally fast swimmers, with moderate maneuverability.

Later versions of the robo-fish, about eight inches long, swim like tuna, which are adapted for even higher swimming speeds and long distances. In tuna, motion is concentrated in the tail and the peduncle region (where the tail attaches to the body), and the amplitude of body motions in this region is greater than in carangiform fish.

Real fish are exquisitely adapted to moving through their watery environment, and can swim as fast as 10 times their body length per second. So far, the MIT researchers have gotten their prototypes close to one body length per second - much slower than their natural counterparts but faster than earlier generations of robotic fish.

The new robo-fish are also more durable than older models - with their seamless bodies, there is no chance of water leaking into the robots and damaging them. Several four-year-old prototypes are still functioning after countless runs through the testing tank, which is filled with tap water.

Current prototypes require 2.5 to 5 watts of power, depending on the robot's size. That electricity now comes from an external source, but in the future the researchers hope to power the robots with a small internal battery.

Later this fall, the researchers plan to expand their research to more complex locomotion and test some new prototype robotic salamanders and manta rays.

"The fish were a proof of concept application, but we are hoping to apply this idea to other forms of locomotion, so the methodology will be useful for mobile robotics research - land, air and underwater - as well," said Valdivia Y Alvarado.

The work was funded by the Singapore-MIT Alliance and Schlumberger Ltd.

About The Researcher :

Kamal Youcef-Toumi

Professor of Mechanical Engineering

Education:
ScD. in Mechanical Engineering, June 1985
Massachusetts Institute of Technology
S.M. in Mechanical Engineering, June 1981
Massachusetts Institute of Technology
B.S. in Mechanical Engineering, June 1979
University of Cincinnati

MIT Service: 22 years
Research Associate and Lecturer June 1985 Dec. 1985
Assistant Professor Jan. 1986 June 1989
Associate Professor (without tenure) July 1989 June 1992
Associate Professor (with tenure) July 1992 June 1998
Professor (with tenure) July 1998 present

Other Related Experience (selections from past 10 years):
Proctor & Gamble Co., Faculty Liaison (Engineering Internship Program) - Oct. 1991 Oct. 1996
Chairman of Undergraduate Curriculum Committee (Dept.) - Sept. 1998 Sept. 1999
Schlumberger Co., Faculty Liaison (Engineering Internship Program) - June 1998 - May 30, 2005
Lawrence Livermore National Laboratory, Faculty Liaison (Engineering Internship Program) - July 2000 - May 30, 2005
Mechanical Engineering Department Research Council - Member - Sept. 2005

Consulting & Patents, etc (past 5 years):
The Gillette Company, Boston, Ma - Dec. 2000 - June 2001
Delta Search Labs, Cambridge, Ma, Advisory Board & Consultant - Sept. 2001 - Present
The Law Firm of George J. Cannata , expert witness - Nov. 2005 - Present

1. "Spectroscopic Systems and Methods", Saptari; Vidi A., Youcef-Toumi; Kamal (Cambridge, MA) United States Patent 7,099,003; August 29, 2006.
2. "Applicator" Shah; Manzoor A., Alvarado; Pablo Valdivia Y, Youcef-Toumi; Kamal, United States Patent 7,055,528; June 6, 2006.
3. "Height Calibration of Scanning Probe Microscope Actuators", El Rifai; Osamah M, Youcef-Toumi; Kamal, United States Patent 7,041,963; May 9, 2006.
4. "Color Image Segmentation in an Object Recognition System", Prempraneerach; Pradya, Youcef-Toumi; Kamal, United States Patent 7,020,329; March 28, 2006.
5. "Image Deconvolution Techniques for Probe Scanning Apparatus", Aumond;Bernardo D., Youcef-Toumi; Kamal, United States Patent 6,661,004; December 9, 2003.
6. "Atomic Force Microscope for Pro¯ling High Aspect Ratio Samples", Aumond; Bernardo D., Youcef-Toumi; Kamal, United States Patent 6,489,611; December 3, 2002.

Principal Publications in last two years:
1. P. Valdivia y Alvarado and K. Youcef-Toumi "Design of Machines with Compliant Bodies for
Biomimetic Locomotion in Liquid Environments", Journal of Dynamic Systems, Measurement, and
Control - March 2006 Volume 128, Issue 1, pp. 3-13.
3. P. Valdivia y Alvarado, and K. Youcef-Toumi, "Performance of machines with flexible bodies
designed for biomimetic locomotion in liquid environments", Proc. IEEE International Conference on
Robotics and automation (ICRA), Barcelona, Spain 2005.
4. El Rifai, O. M. and K. Youcef-Toumi., "Trade-offs and Performance Limitations in Mechatronic
Systems: A Case Study", Annual Reviews in Control, 2, 2004.
5. El Rifai, K., El Rifai, O., and K. Youcef-Toumi., "On Robust Adaptive Switched Control", American
Control Conference 2005, Portland, OR.
6. El Rifai, K., and K. Youcef-Toumi., "Robust Adaptive Scheduled Switched Control", Conference on
Decision and Control 2005, Seville, Spain
7. Shilpiekandula V, Youcef-Toumi K. "Modeling and Control of a Programmable Filter for Separation
of Biologically Active Molecules", American Control Conference, 8-10 Jun 2005, pp 394 - 399.
8. El Rifai OM, Youcef-Toumi K, "Adaptive Control of Uncertain Dynamics at the Nano-scale", 44th
IEEE Conference on Decision and Control, 2005 and 2005 European Control Conference. CDC-ECC
2005. 12-15 Dec. 2005, pp 1180 - 1184.
9. El Rifai K, El Rifai OM, Youcef-Toumi K. "Modeling and Control of AFM-based Nano-Manipulation
Systems", In Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 18-
22 April 2005, pp 157 - 162., Barcelona, Spain.
10. El Rifai, O. M. and K. Youcef-Toumi., "Trade-offs and Performance Limitations in Mechatronic
Systems: A Case Study", Annual Reviews in Control, 2, 2004.
11. El Rifai, O. M. and K. Youcef-Toumi. "On Automating Atomic Force Microscopes: An Adaptive
Control Approach", Control Engineering Practice, to appear, 2006.
12. El Rifai K, El Rifai OM, Youcef-Toumi K. "Modeling and Control of AFM-based Nano-manipulation
Systems", In Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 18-
22 April 2005, pp 157 - 162., Barcelona, Spain.
13. D. J. Burns and K. Youcef-Toumi. "On single-molecule dna sequencing with functionalized carbon
nanotube probes", In 4th IFAC-Symposium on Mechatronic Systems, 2006.
14. D. J. Burns and K. Youcef-Toumi "Shortening carbon nanotube-tipped AFM probes", In 4th
International Symposium on Nanomanufacturing, 2006.
16. El Rifai Osamah, and Youcef-Toumi, Kamal, "Adaptive Control of Atomic Force Microscopes", 3rd
IFAC Symposium on Mechatronic Systems, Sydney, Australia, September 6-8, 2004.
17. El Rifai Khalid, El Rifai Osamah, and Youcef-Toumi, Kamal, "On Dual Actuation in of Atomic Force
Microscopes", American Control Conference, Boston, Massachusetts, USA, June 30- July 2, 2004.
19. El Rifai Osamah, and Youcef-Toumi, Kamal, "Design and Control of Atomic Force Microscopes",
American Control Conference, Denver, Colorado, USA, June 4-6, 2003.
20. El Rifai Osamah, and Youcef-Toumi, Kamal, "Trade-offs and Performance Limitations in Atomic
Force Microscope Feedback System", 2nd IFAC Symposium on Mechatronic Systems, Berkeley, CA,
USA, December 9-11, 2002.
24. V Saptari, K. Youcef-Toumi, J. Zhang, "NIR measurements of glucose in synthetic biological
solutions using high-throughput angle-tuned filter spectrometer," Proc. SPIE Int. Soc. Opt. Eng., Vol.
5325, pp. 1-10 (2004)
25. V. Saptari and K. Youcef-Toumi, "Design of a Mechanical-tunable
Filter Spectrometer for Noninvasive Glucose Measurement," Journal of Applied Optics, 2004.
26. V. Saptari and K. Youcef-Toumi, "Design of a mechanical-tunable filter spectrometer for noninvasive
glucose measurement," Applied Optics, Vol 43, No. 13, pp. 2680-2688 (2004)

Scientific & Professional Societies:
IEEE Society - Member
ASME Society - Member
Sigma Xi Society - Elected Member

Honors & Awards:
Presidential Young Investigator, National Science Foundation Award in Recognition of Research and Teaching Accomplishments. (A two- year appointment.), 1987
Carl Richard Soderberg Career Development Chair, Professorship in Power Engineering. 1988 - 1990
Winner of the Best Paper Award of the ASME Journal of Dynamic Systems, Measurement and Control. 1999

Institutional and Professional Service in the last five years:
National Science Foundation, Washington, DC, review committees - 1987 - present
ASME Journal of Dynamic Systems Measurement and Control - Associate Editor - 1989 - 1992

Contact information of Kamal :

Room 3-348
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge MA 02139-4307
Phone: 617-253-2216  
Fax: 617-258-6575  
Email: youcef@mit.edu

Administrative Contact:
Lois Graziano
Room 3-348
Phone: 617-253-2204  
Email: loisg@mit.edu