University of California, Berkeley
Department of Integrative Biology
3060 Valley of Life Sciences Building #5130
Berkeley, California 94720-3140
Lab phone: 510-643-5183
Personal : 510-499-5164
Email: tlibby [at] berkeley.edu
I am a mechanical engineering PhD student interested in the dynamics and control of rapid locomotion. My recent work focuses on the role of inertial reaction forces in maneuvering – the ability to swing limbs or tails to stabilize leaps or generate rapid turns. If you have ever swung your arms to catch your balance, you have experienced this phenomenon! Lizards, with their long and relatively massive tails harness this mechanism in a more spectacular fashion, righting themselves mid-air after a fall, stabilizing short leaps, and turning around in a fraction of second.
Researchers have long suspected that tails might play such a role, going at least as far back as the discovery of the small theropod dinosaur Deinonychus. In my work, I have used dynamics models grounded in careful morphometrics to elucidate the contribution of a swinging tail in freely running animals. These models act as a virtual control – predicting the effect of removing or stiffening a tail during a behavior, or decoupling the portion of maneuver due to tail swing from the entire behavior. The physics behind these models also enable the extraction of fundamental principles behind the design of a good tail. While dynamics models are extremely powerful, they are full of assumptions. As a physical embodiment of our ideas, simple robotic test beds have provided valuable insight into the real-world constraints on tail-induced maneuvers, and paved the way for the next generation of highly mobile robots.
Chang-Siu, E., Libby, T., Brown, M., Full, R.J., and Tomizuka, M. A nonlinear feedback controller for aerial self-righting by a tailed robot. Robotics and Automation (ICRA), 2013 IEEE International Conference on. IEEE, 2013.
Johnson, A., Libby, T., Chang-Siu, E., Tomizuka, M., Full, R.J., and Koditschek, D. Tail assisted dynamic self righting. 15th Int. Conf. on Climbing and Walking Robots (CLAWAR), July 2012.
Libby, T., Moore, T. Y., Chang-Siu, E., Li, D., Cohen, D. J., Jusufi, A. and Full, R. J. (2012) Tail-assisted pitch control in lizards, robots and dinosaurs. Nature 481, 181.
Chang-Siu, E., Libby, T., Tomizuka, M, Full, R. J., “A lizard-inspired active tail enables rapid maneuvers and dynamic stabilization in a terrestrial robot,” Intelligent Robots and Systems (IROS), 2011 IEEE/RSJ International Conference on , vol., no., pp.1887-1894, 25-30
Byrnes, G., Libby, T., Lim, N. T.-L. and Spence, A. J. (2011). Gliding saves time but not energy in Malayan colugos. J. Exp. Biol. 214, 2690-2696.