Meeting Abstract

69.3  Tuesday, Jan. 6  Quadrupedal Turning Behaviors: Mechanics and Gait Preference MORENO, C.A.*; BIEWENER, A.A.; Harvard University cmoreno@oeb.harvard.edu

Turning behaviors are critically important for many terrestrial animals and have been studied in a variety of taxa. Recent work in our lab has described the functional roles the limbs of cursorial quadrupeds in terms of the linear impulses produced during each stride of a 90 turn as well as how each limb contributes to the overall roll, pitch and yaw moments about the center of mass (COM). We found that both the forelimbs and hindlimbs contribute substantially to the production of lateral impulse in the turn direction, but that the outside limb produces more vertical and more lateral impulse than the corresponding inside limb. We also found that during trotting there was very little overall moment produced about the COM, whereas in galloping, there were large, alternating pitching moments, as well as substantial roll and yaw moments produced by all four limbs. With this foundation, we are developing a model to predict how upright animals initiate and execute turns while maintaining traction and stability. This work suggests a continuum between a continuous turning gait on one hand, where each stride is functionally similar to the previous stride, versus a discrete maneuver on the other, where the behavior is performed over a much shorter time scale resulting in differences in limb function from one stride to the next. It seems likely that during predator-prey interactions animals would use a combination of continuous, high-speed steady turning along with discrete, quick changes of direction to elude their predator or capture their prey. Because it has been frequently observed that racing animals such as dogs and horses prefer an inside lead gallop to an outside lead gallop, in this study we also address the mechanical consequences of lead preference and handedness during high-speed locomotion.