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Title: A biologically-inspired multi-modal wing for aerial-aquatic robotic vehicles
Author: Lock, Richard J.
ISNI:       0000 0004 2725 078X
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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The majority of robotic vehicles that can be found in the engineering community today are bound to operations within a single medium. This dissertation begins to lay the foundation for a generation of vehicles capable of multi-modal locomotion, allowing ambulatory abilities in more than one media, specifically focussing on a vehicle with both aerial and aquatic modes of locomotion. The flapping mechanism under investigation is used in both air and water, driving a wing capable of morphing its shape dependant on the medium of operation. Through a combi- nation of numerical analysis along with empirical analysis (gathered using a purpose built mechatronic system), the feasibility of using the dual-use mechanism has been demon- strated, along with quantifying projected performance. A detailed numerical model of the morphing wing supporting the development of the multi- modal vehicle has been formulated that combines blade element analysis (BEA), which models the hydrodynamics, along with additional inertial dynamics during the aquatic phase. The aerial phase of the model was developed based on established formuli relating to flapping aerial flight. The initial numerical model demonstrated the importance of the ability to operate with under-constrained kinematics in order to provide the desired highly manoeuvrable platform. Referring to the developed specification, the numerical model showed that in order to be able to achieve the vehicles minimum power velocity, i.e. enabling loitering capabilities, the wing semi-span would need to be ~ 0.35m and the chord would need to be ~ 0.08m. The mechatronic testing platform, consisting of a 2 degree-of-freedom (dof') flapping mech- anism, demonstrated that the required power to flap the retracted foil in water greatly reduces compared to the extended, with an observed reduction of ~ 75% in required me- chanical power into the system. Through standardisation of the results by means of the non-dimensionalised St number, the observed performance measures of the propulsive ef- ficiency and thrust coefficient have been shown to be similar for both the extended and retracted foils. Mechanical propulsive efficiencies of 0.65 were found for both foil shapes (i.e. outstretched ana' retracted) provided parameters were standardised during compar- isons, specifically the Strouhal number and the effective angle of attack, demonstrating the feasibility of using a retracted foil on future robotic vehicles using a flapping wing in both aerial and aquatic substrates.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available