Locomotion study of a single actuated, modular swimming robot

Abstract

This paper introduces a concept for a biologically inspired modular swimming robot, which is able to perform different swimming styles of steady swimming species. Therefore the robot has two kinds of modules: 1. a basic structure, which creates the required torque and determines the swimming direction of the robot; 2. effector modules that generate the robot's propulsion in interaction with the surrounding liquid. Due to the specific task, the effector modules are exchangeable.This approach enables the gain of technical and biological knowledge: The results of research tend to a design that is suited to fulfill tasks in particular situations when common marine propeller driven robots are not able to work (e.g. an environment with many plants). In addition, the permutation of bio-analogous features in a robot improves understanding of the biological antetype.The current design of the effector modules is inspired by undulant swimming species, mainly sea snakes and eels. Biological research and mathematical modeling yielded to a three segmented tail structure. The coupling of the segments to each other uses spring elements.

Reducing complexness of control by intelligent mechanics in undulant swimming robots

“…The sinusoidal function for stimulating the model illustrates eqn. (5). t labels the time, w a weighting factor.…”

“…Therewith an easy technical implementation is facilitated. The algorithm of this conversion is described in Fremerey et al [5] in detail.…”

“…Due to the results of simulation, the stiffness is reduced from head to tail by a factor of 10 concerning each joint. Conveying the rotational stiffness into a linear one (Fremerey et al [5]), the stiffness amounts 77.5 N·m −1 for joint one (starting head side) and 7.75 N·m −1 for joint two.…”

“…For performing an anguilliform and a thunniform swimming mode, the structure of the robot is a modular one, composing of two different kinds of modules: (i) the basic structure and (ii) the effector modules [1,3,4,6,7,11,12,16]. The connection among the effector modules is realized by a joint with a manually tunable intrinsic passive compliance.…”