Showing papers on "Aquatic locomotion published in 2018"

Optimal design and energy harvesting performance of carangiform fish-like robotic system

Abstract: Aquatic unmanned vehicles (AUVs) are making a shift to more efficient swimming designs inspired from nature that utilize more flexible materials to make the system more mimetic. Creating more mimetic body caudal fin swimming AUV designs means that aquatic locomotion is achieved through an oscillatory body undulation. This oscillatory motion can be modeled as a spatio-temporal function by replicating the behavior of spinal flexion. A computational fluid dynamic analysis determined that the frequency which produces enough thrust to overcome body drag is greater than 2.5 Hz. The spatio-temporal function and the frequency range (2.5–5 Hz) are then defined for two aquatic AUVs of lengths 0.4 and 1 m. Because these systems express an oscillatory body undulation, they have energy harvesting potential where piezoelectric patches can be attached along the fish length. Investigations into impacts of piezoelectric material length, placement, and frequency of oscillation for the two respective fish lengths are carried out using a gradient decent method to determine the optimal system arrangement for both systems that generate maximum power. The undulatory motion for 0.4 m is scaled from the 1 m length but the optimal attachment location of the piezoelectric layer always at the tip of the tail where the largest flexural change occurs. The ratio of the piezoelectric length to fish length for the two considered fish lengths is found to be 0.237. This analysis is very beneficial for the design of efficient carangiform fish-like robots.