Force Measurement of Basilisk Lizard Running on Water

abstract: Basilisk lizards are often studied for their unique ability to run across the surface of water. Due to the complicated fluid dynamics of this process, the forces applied on the water’s surface cannot be measured using traditional methods. This thesis presents a novel technique of measuring the forces using a fluid dynamic force platform (FDFP), a light, rigid box immersed in water. This platform, along with a motion capture system, can be used to characterize the kinematics and dynamics of a basilisk lizard running on water. This could ultimately lead to robots that can run on water in a similar manner.Dissertation/ThesisMasters Thesis Mechanical Engineering 201

Western and Clark's grebes use novel strategies for running on water

Few vertebrates run on water. The largest animals to accomplish this feat are Western and Clark’s grebes (Aechmophorus occidentalis and clarkii). These birds use water running to secure a mate during a display called rushing. Grebes weigh an order of magnitude more than the next largest water runners, basilisk lizards (B. basiliscus), and therefore face a greater challenge to support their body weight. How do these birds produce the hydrodynamic forces necessary to overcome gravity and sustain rushing? We present the first quantitative study of water running by grebes. High-speed video recordings elucidate the hindlimb movements of grebes rushing in the wild. We complement these findings with laboratory experiments using physical models and a preserved grebe foot to estimate how slapping the water surface contributes to weight support. Our results indicate that grebes employ three novel tactics to successfully run on water. First, rushing grebes use exceptionally high stride rates, reaching 10 Hz. Second, grebe foot size and high water impact speed allow grebes to generate up to 30-55% of the required weight support through water slap alone. Lastly, flattened foot bones reduce downward drag, permitting grebes to retract each foot from the water laterally. Together, these mechanisms outline a water running strategy qualitatively different from that of the only previously-studied water runner, the basilisk lizard. The hydrodynamic specializations of rushing grebes could inform the design of biomimetic appendages. Furthermore, the mechanisms underlying this impressive display demonstrate that evolution can dramatically alter performance under sexual selectionOrganismic and Evolutionary Biolog

Re-designing materials for biomedical applications: from biomimicry to nature-inspired chemical engineering

Gathering inspiration from nature for the design of new materials, products and processes is a topic gaining rapid interest among scientists and engineers. In this review, we introduce the concept of natureinspired chemical engineering (NICE). We critically examine how this approach offers advantages over straightforward biomimicry and distinguishes itself from bio-integrated design, as a systematic methodology to present innovative solutions to challenging problems. The scope of application of the nature-inspired approach is demonstrated via examples from the field of biomedicine, where much of the inspiration is still more narrowly focused on imitation or bio-integration. We conclude with an outlook on prospective future applications, offered by the more systematic and mechanistically based NICE approach, complemented by rapid progress in manufacturing, computation and robotics. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’

Locomation strategies for amphibious robots-a review

In the past two decades, unmanned amphibious robots have proven the most promising and efficient systems ranging from scientific, military, and commercial applications. The applications like monitoring, surveillance, reconnaissance, and military combat operations require platforms to maneuver on challenging, complex, rugged terrains and diverse environments. The recent technological advancements and development in aquatic robotics and mobile robotics have facilitated a more agile, robust, and efficient amphibious robots maneuvering in multiple environments and various terrain profiles. Amphibious robot locomotion inspired by nature, such as amphibians, offers augmented flexibility, improved adaptability, and higher mobility over terrestrial, aquatic, and aerial mediums. In this review, amphibious robots' locomotion mechanism designed and developed previously are consolidated, systematically The review also analyzes the literature on amphibious robot highlighting the limitations, open research areas, recent key development in this research field. Further development and contributions to amphibious robot locomotion, actuation, and control can be utilized to perform specific missions in sophisticated environments, where tasks are unsafe or hardly feasible for the divers or traditional aquatic and terrestrial robots

Dimensionamento e simulação de um robô anfíbio biomimético

Este trabalho tem como principal objetivo destacar e avaliar a tartaruga-de-água-doce (Trachemys scripta elegans) como modelo de bioinspiração para o desenvolvimento de um robô biomimético, comparativamente com o mais estudado modelo baseado em tartaruga-marinha. Com o auxílio de um programa de simulação para robôs é comparado o desempenho do modelo virtual da tartaruga de água-doce com o modelo da tartaruga marinha e retiradas as respetivas conclusões. Será também avaliada a viabilidade do simulador para o desenvolvimento das variadas características de um sistema robotizado. Foi realizado um estudo acerca dos aspetos estruturais e funcionais dos modelos biológicos, dos quais se retiraram os aspetos vantajosos para serem adaptados ao sistema robotizado. Foram abordadas as principais componentes para construção de um robô (plataforma, atuadores e sensores, etc.) e realizada uma exploração profunda das funcionalidades do simulador.The main goal of this work consists in highlighting and evaluating a freshwater turtle (Trachemys scripta elegans) as a bioinspiration model for a biomimetic robot, comparatively to the most recurrent model (marine turtle model based robots). With the aid of a simulation software specially built for robotics, the performance of both virtual robot models (marine and freshwater) will be compared and conclusions will follow. The feasibility of the simulation software for developing the various features of a robot will also be evaluated. After extensive research about structural and functional aspects of both turtle types, the advantageous characteristics were applied to the robotic system model. The main components of a robot were approached (platform, actuators, sensors, etc.) and a deep exploration of the software functionalities was carried out

MODELLING AND EXPERIMENTAL VERIFICATION OF LIZARDS' FLEXIBLE TRUNKS' EFFECTS ON ENERGETICALLY EFFICIENT LOCOMOTION

Master'sMASTER OF ENGINEERIN

Mini-/Micro-Scale Free Surface Propulsion

This work reports theoretical studies and experimental proofs of the propulsion of mini-/micro-scale floating objects that propel on air-liquid interface by using two different principles. The devices are extremely simple and do not include any moving parts. The first principle takes advantage of three-phase contact line oscillation that is activated by AC electrowetting on dielectric (EWOD) to propel the floating object. The capillary wave that is generated by the free surface oscillation is visualized by using the Free-Surface Synthetic Schlieren (FS-SS) method. A 3-D flow field sketch is constructed based on the flow visualizations and PIV measurements. The flow field and trajectories of seeded particles suggest that Stokes drift is the responsible mechanism for the propulsion. The propulsion speed of the floating object highly depends on the amplitude, frequency, and shape of the EWOD signal. These phenomena are also explained by the measured oscillation amplitudes and Stokes drift relations. Additionally, it is shown that a wider EWOD electrode generates a faster propelling speed. Finally, with stacked planar receiver coils and an amplitude modulated signal, a wirelessly powered AC EWOD propulsion is realized. The second principle of floating object propulsion is the Cheerios effect, which is also generally known as lateral capillary force. Four common physical configurations (interactions between two infinite vertical walls, two vertical circular cylinders, two spheres, and a sphere and a vertical wall) are reviewed. Through theoretical analysis, it has been revealed that not the wettability of the surface but the slope angle of the object is the most important parameter for the Cheerios effect. A general rule for this effect is that the lateral capillary force is attractive if the slope angles of the interacting objects have the same sign, otherwise the force is repulsive. In addition to the surface wettability, the size and the density of floating spheres are also important for the slope angle. Active control of the Cheerios effect is achieved by implementing EWOD and dielectrowetting methods to adjust the surface wettability. By sequentially activating micro-fabricated EWOD/dielectrowetting electrodes, linear translations of floating objects in the small scale channel are accomplished. A continuous rotational motion of the floating rod is achieved in a circular container by the EWOD method