Dynamical locomotion analysis and a model for the peristaltic motion of earthworms

We focus an earthworm peristaltic motion that propagates the receding waves generated by contraction and expansion of arthromeres. This type of motion has the advantage of being flexible for locomotion and can be easily applied to narrow or rough areas. In this paper, peristaltic motion is analyzed from picture images of an earthworm crawling in a straight line. We also examine how to change the length of each arthromere and its diameter, when receding waves propagate the earthworm body. From our experimental results, we model the dynamics of the contractions in the circular and longitudinal muscle as a 2nd-order lag element. As a whole, such locomotive model is proposed that muscle elements are activated by the impulsive input that sequentially propagates a series of arthromeres. It is clear that the experimental results positively represent the proposed model