Comparative Biomechanics Publications

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We found that cockroaches and crabs generate one Joule of mechanical energy/kg to move their body one meter just as do birds, mammals and humans do. Equivalent gaits (e.g. trots and gallops) may be present in 4-, 6- and 8-legged runners. Ghost crabs change gait from a trot to a gallop at the same stride frequency and speeds as a mouse.

Two-, four-, six- and eight-legged animals can produce similar force patterns during locomotion. They all can bounce as they run using 2 alternating sets of legs as springs. One human leg works like 2 dog legs, 3 cockroach legs and 4 crab legs. All show a pattern similar to a bouncing ball or a pogo stick.

Crabs and cockroaches do not move like most robots do. Most legged robots try to be wheel-like. They try to achieve a smooth ride with little oscillation of the body up and down, little acceleration and deceleration. No legs push against one another, so as to be most efficient. Also they try to be like a stool - 3 legs on the ground to always keep their balance and be statically stable.

Crabs and cockroaches have the advantage of many legs, a wide base of support and a low center of gravity to be very stable, as do many of the legged robots do. They can be stool-like. However, even when they walk, their bodies move up and down and function like upside-down pendulums to conserve energy. Crabs and cockroaches can also be fast, maneuverable and run. We have redefined a walk and a run. We use to think that a run meant you had to leave the ground, have an aerial phase. But no more. A run is where you bounce like a ball or your legs work like a pogo stick. Crabs and cockroaches can move dynamically and bounce like a ball. They are not restricted to moving one leg at a time until they are sure they have a good foot-hold. They can have kinetic energy, energy of motion, bridge the gap between poor or non-existent foot-holds. Crabs and cockroaches can be dynamically stable (not stable at every instant, but over one cycle of leg movements).

Moving up and down, accelerating and decelerating the body is desirable for an animal. Animals use there legs like pendulums and springs. Legs pushing against one another can minimize the forces at the joints. Animals move dynamically. Why not use these ideas to give robots both stability and speed and maneuverability?

Full, R.J. and Koditschek, D.E. 1999. Templates and anchors: Neuromechanical hypotheses of legged locomotion on land. J exp bio, 202, 3325-3332. * Full Text PDF

Jindrich, D.L. and Full, R.J. 1999. Many-legged maneuverability: dynamics of turning in hexapods. J. exp Bio. 202, 1603-1623. Full Text PDF

Kubow T. M. and R.J. Full. 1999. The role of the mechanical system in control: A hypothesis of self-stabilization in hexapedal runners. Phil. Trans. Roy. Soc. London B. 354, 849-861.

Martinez, M. M., Full, R. J., and Koehl, M. A. R. 1998. Underwater punting by an intertidal crab: A novel gait revealed by the kinematics of pedestrian locomotion in air versus water. J. exp. Bio. 201, 2609-2623. Full Text PDF

Kram, R., Wong, B. and Full, R.J. 1997. Three dimensional kinematics and limb kinetic energy of running cockroaches. J. exp Bio. 200, 1919-1929. Full Text PDF

Full, R.J. Invertebrate locomotor systems. 1997. In The Handbook of Comparative Physiology. (Ed. W. Dantzler). Oxford University Press. pp. 853-930. Full Text PDF

Full, R.J., Yamauchi, A. and Jindrich, D.L. 1995. Single leg force production: cockroaches righting on photoelastic gelatin. J. exp. Bio. 198, 2441-2452. Full Text PDF

Full, R.J. and Ahn, A. 1995. Static forces and moments generated in the insect leg: comparison of a three-dimensional musculoskeletal computer model with experimental measurements. J. exp Bio. 198, 1285-1298. Full Text PDF

Queathem, L. and Full, R.J. 1995. Variation in jump force production within an instar of the grasshopper Schistocerca americana. J. Zool. London 235, 605-620.

Ting, L.H., Blickhan, R. and Full, R.J. 1994. Dynamic and static stability in hexapedal runners. J. exp Bio. 197, 251-269. Full Text PDF

Full, R.J. 1994. The importance of mechanical systems in understanding arthropod neural control of locomotion. Proc. An.Yale Workshop on Adaptive and Learning Systems 8, 21-26.

Blickhan, R. and Full, R.J. 1993. Similarity in multilegged locomotion: Bouncing like a monopode. J. comp. Physiol. 173, 509-517.

Full, R.J., Earls K., Wong, M. A., Caldwell, R.L. 1993. Locomotion like a wheel? Nature 365, 495.

Blickhan, R., Full, R.J. and Ting, L.H. 1993. Exoskeletal strain: evidence for a trot-gallop transition in rapidly running ghost crabs. J. exp Bio. 179, 301-321. Full Text PDF

Full, R.J. and Koehl, M.A.R. 1993. Drag and lift on running insects. J. exp Bio. 176, 89-101. Full Text PDF

Full, R.J. 1993. Integration of individual leg dynamics with whole body movement in arthropod locomotion. In Biological Neural Networks in Invertebrate Neuroethtology and Robots. (eds. R. Beer, R. Ritzmann and T. McKenna). Academic Press. Boston. pp. 3-20.

Blickhan, R. and Full, R.J. 1992. Mechanical work in terrestrial locomotion. In Biomechanics: Structures and Systems A Practical Approach. (ed. A. Biewener). IRL at Oxford University Press. New York. pp. 75-96.

Biewener, A. and Full, R.J. 1992. Force platform and kinematic analysis. In Biomechanics: Structures and Systems A Practical Approach. (ed. A. Biewener). IRL at Oxford University Press. New York. pp 45-73.

Full, R.J. and Weinstein, R.B. 1992. Integrating the physiology, mechanics and behavior of rapid running ghost crabs: slow and steady doesn't always win the race. Amer. Zool. 32, 382-395.

Full, R.J. 1991. The concepts of efficiency and economy in land locomotion. In Efficiency and Economy in Animal Physiology. (ed. R.W. Blake). Cambridge University Press, New York. pp. 97-131.

Full, R.J. 1991. Animal motility and gravity. Physiologist 34, S15-18.

Full, R.J. and Blickhan, R. and Ting, L.H. 1991. Leg design in hexapedal runners. J. exp Bio. 158, 369-390.

Full, R.J. and Tu, M.S. 1991. Mechanics of a rapid running insect: two-, four-, and six-legged locomotion. J. exp Bio. 156, 215-231.

Full, R.J. and Tu, M.S. 1990. Mechanics of six-legged runners. J. exp. Bio. 148, 129-146.

Full, R.J., Tu, M.S. and Ting, L. 1989. Dynamics of insect locomotion compared to hexapod walking machines. Proc. Amer. Soc. Mech. Engineering DSC17, 35-40.

Full, R.J. 1989. Mechanics and energetics of terrestrial locomotion: From bipeds to polypeds. In Energy Transformations in Cells and Organisms. (ed. W. Wieser and E. Gnaiger). Thieme, Stuttgart, NY. pp. 175-182.

Blickhan, R. and R.J. Full. 1987. Locomotion energetics of the ghost crab: II. Mechanics of the centre of mass during walking and running. J. exp. Bio. 130, 155-174.

Herreid II, C.F. and R.J. Full. 1986. Locomotion of hermit crabs (Coenobita compressus) on beach and treadmill. J. exp. Bio. 120, 283-296.