Meeting Abstract

P2.168  Tuesday, Jan. 5  A Self-Propelled Robotic Swimmer as a Biomechanical Testbed: Swimming Performance and Axial Length of the Intervertebral Joints HIROKAWA, J*; ROBERTS, S; FRIAS, C; KRENITSKY, N; DE LEEUW, J; LONG, J; PORTER, M; Vassar College; Vassar College; Vassar College; Vassar College; Vassar College; Vassar College; Vassar College johirokawa@vassar.edu

To directly measure how skeletal morphology impacts swimming performance, we designed and built the Mobile Autonomous Robot for Mechanical Testing (MARMT). MARMT is a self-propelled surface swimmer with programmable locomotor behaviors and swapable biomimetic skeletal elements. We programmed MARMT to vary tailbeat frequency and swimming mode (steady undulation and transient escape). As the propulsive element, we built and installed constant-length biomimetic vertebral columns that varied number of vertebrae to alter the axial length of the intervertebral joints. The biomimetic vertebral column consisted of a notochord, made from gelatin cross-linked with glutaraldehyde, encircled by a series of rigid plastic ring centra. We varied the number of intervertebral joints from zero to twelve. Three replicates of each vertebral column were tested during straight swimming and escape responses; five different tail-beat frequencies were used while tail-beat amplitude was held constant. Response variables were MARMT’s velocity, acceleration, yaw rotation, tail curvature, and lateral amplitude of the tail. Preliminary analysis supports the hypothesis that increased frequency and shorter intervertebral joints lead to higher maximum and mean accelerations. Extrapolating our results to biological systems, shorter intervertebral joints may provide an adaptive advantage for bursts of speed. This may allow for quicker escapes from predators or faster attacks on prey. This work was supported by NSF DBI-0442269 and IOS-0922605.