Worm-like locomotion as a problem of nonlinear dynamics

Non-pedal forms of locomotion show their advantages in inspection techniques or applications to the medical technology for diagnostic systems and minimally invasive surgery. Observing the locomotion of worms, one recognizes conversion of (mostly periodic) internal and internally driven motions into a change in the external position (undulatory locomotion). This paper presents some theoretical and practical investigations of worm-like motion systems that have the earthworm as a live prototype. The locomotion of worms can be described by introduction of nonlinear non-symmetric frictional forces. In the first part of the paper these systems are modelled in form of straight chains of interconnected mass points. The ground contact can be described by non-symmetric dry friction. The investigations are concentrated on motion in a tube or channel, and on motion on a horizontal plane as well. In both cases, the body is modeled as a viscous Newtonian fluid. The effect of the ma ss flow through a cross section on the disturbance and material parameters (viscosity, dimensions) is discussed. The paper presents first prototypes of technically implemented artificial worms.