Dynamics of the walking stick insect

Abstract

The gait dynamics of the walking stick insect (Carausius morosus) is investigated in order to gain insight into the biological constructional conception of walking as a basis for future technical developments. The insect is modeled by a rigid multibody system consisting of 19 bodies (one central body and six legs with three segments each) and forming multiple closed kinematic chains corresponding to the gait pattern. Thus, the changing structure during the walking motion yields a dynamic system with time-varying topology. An investigation of the tripod gait on a horizontal plane is reported. This is a very orderly gait pattern in which the front and rear legs on the left side together with the middle leg on the right side move in unison and form the left tripod, while the remaining legs conversely form the right tripod. Thus, either three or six legs have ground contact simultaneously. The results of the computer simulation are compared with measurements of insect leg movements, confirming the possibility of modeling natural walking motion by mechanical means.