Pedal-Like Locomotion Mechanism Modeled on Pedal Crawling of Terrestrial Gastropod

Abstract

When a snail is crawling on a ground, dark transverse bands appear on the sole of the snail and propagate from the posterior end of the foot to the anterior end. The dark bands are essentially the regions of longitudinal muscle contraction of the surface of foot, which form pedal waves. We paid attention to the manner of formation and propagation of the pedal wave. A pedal-like locomotion mechanism is developed of which moves forward by a pedal crawling like the snail. The pedal mechanism consists of eight units of the contraction mechanism which performs such a series of contraction motions as longitudinal contraction of the sole, lifting the sole surface and propagation of pedal wave by the use of a link mechanism and a SMA as actuator. As a result of the experiment on locomotion of the pedal mechanism, it was found that the locomotion velocity of the pedal mechanism was in proportion to both the propagation velocity of a pedal wave and the number of a pedal wave past on the sole per unit time, but an increase of the frequency of a pedal wave caused a decrease in traction of the pedal mechanism.