Energetic analysis and experiments of earthworm-like locomotion with compliant surfaces.

The energy consumption of worm robots is composed of three parts: heat losses in the motors, internal friction losses of the worm device and mechanical energy locomotion requirements which we refer to as the cost of transport (COT). The COT, which is the main focus of this paper, is composed of work against two types of external factors: (i) the resisting forces, such as weight, tether force, or fluid drag for robots navigating inside wet environments and (ii) sliding friction forces that may result from sliding either forward or backward. In a previous work, we determined the mechanical energy requirement of worm robot locomotion over compliant surfaces, independently of the efficiency of the worm device.

Conditions for worm-robot locomotion in a flexible environment: theory and experiments.

Biological vessels are characterized by their substantial compliance and low friction that present a major challenge for crawling robots for minimally invasive medical procedures. Quite a number of studies considered the design and construction of crawling robots; however, very few focused on the interaction between the robots and the flexible environment. In a previous study, we derived the analytical efficiency of worm locomotion as a function of the number of cells, friction coefficients, normal forces, and local (contact) tangential compliance.

Analysis of wormlike robotic locomotion on compliant surfaces.

An inherent characteristic of biological vessels and tissues is that they exhibit significant compliance or flexibility, both in the normal and tangential directions. The latter in particular is atypical of standard engineering materials and presents additional challenges for designing robotic mechanisms for navigation inside biological vessels by crawling on the tissue. Several studies aimed at designing and building wormlike robots have been carried out, but little was done on analyzing the interactions between the robots and their flexible environment.