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Thesis (M.A.)--California State University, Chico, 2005. / Includes abstract. Includes bibliographical references (leaves: 83-87).

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 90-96). Also available on the World Wide Web.

Thesis (M.S.E.S.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillments of the requirements for The Masters of Science in Exercise Sciences concentration in Athletic Training." "A thesis entitled"--at head of title. Bibliography: leaves 43-46.

Thesis (M.S.E.S.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science degree in Exercise Science." "A thesis entitled"--at head of title. Bibliography: leaves 42-46.

Thesis (M.A.)--University of North Carolina, Chapel Hill, 2003. / Includes bibliographical references (leaves 41-43). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.A.)--University of North Carolina, Chapel Hill, 2003. / Includes bibliographical references (leaves 41-43).

Many animals interact with the air-water interface during locomotion. Such location either involves moving through the water's surface or moving atop the water surface. This dissertation aims to investigate both of these forms of locomotion in frogs. First we quantified the kinematics of skittering, jumping on top the water's surface without sinking, in two species of frog, Acris crepitans and Euphlyctis cyanophlyctis. We found that what was described as "skittering" locomotion in Acris crepitans is actually more akin to porpoising. A. crepitans begins and ends each jump during their interfacial behavior under the water surface. These frogs may be unable to perform true skittering locomotion due to not being able to retract their hindlimbs fast enough. E. cyanophlyctis, however, does stay above the water surface during this mode of locomotion. We found that Euphlyctis is highly maneuverable during skittering locomotion compared to other inertial based water-surface traversing animals. Not only can they turn up to 80° between subsequent jumps, they also perform this behavior in close proximity to each other without collision. Next, we investigated control mechanisms used by frogs when jumping from water. Prior research has identified frogs of the genus Euphlyctis as high jumpers. But previous studies only considered their maximal performance. Here, we investigated how these frogs modulate propulsive force in order to control their jump height. We linked the frog limb kinematics to the jump force by modeling the added mass produced by the foot's motion. / Doctor of Philosophy / There are many animals that move across or through the water's surface. Most of them are very small and light and can thus be supported by surface tension. Larger animals instead must produce the force needed to stay afloat by moving quickly. Previous research has looked at the physics involved in running on the water surface in basilisk lizards and grebes. However, the ability of frogs to jump on the water surface (a behavior known as "skittering") has never been studied. In this dissertation, we examine the water-surface traversal of two frog species, Acris crepitans and Euphlyctis spp., using high-speed videography. Unlike previous human observations in the literature, we found that Acris does not stay atop the water's surface during its jumping behavior and instead begins and ends each jump under the water. This is similar to porpoising in animals like dolphins. Euphlyctis, however, does stay above the water during this jumping behavior. We found that these frogs can turn sharply between jumps which has not been observed in any other large water-runners. Additionally, we studied the ability of Euphlyctis to jump high in the air starting from floating on the water surface. These frogs are interesting to study because they can jump unusually high compared to other species of similar size and shape. We found that when shown insects at different heights, these frogs can control their jump height and only jump as high as necessary. By tracking the frogs' limbs during jumping we investigated several possible ways these frogs controlled their jump height.

Jumping is one of the common methods that flight capable birds use to initiate the take-off phase. Flapping-wing robots that can achieve jumping take-off similar to birds will be significantly valuable since they can reduce the workload of the wing in producing the instantaneous power required for take-off and enables remote operations as well. This thesis progresses the state of the art in leg based jumping systems for flapping-wing robots through a contribution to the fundamental understanding of jumping dynamics and the development of experimentally validated simulation tools. Three reference leg postures are identified from video analysis of a rook take-off: stand, crouch and extended. Birds often use different kinematic patterns for the leg flexion (stand to crouch) and extension (crouch to extended) phases. This is made possible by their multi degree of freedom (Dof) leg structure and complex, multi actuated muscle systems. As an alternative strategy, a conceptual design of a singly actuated jumping leg is proposed where a multi Dof segmented leg is linked to a single actuator. The structure is based on the avian leg and foot anatomy. The study identifies that a dynamically unstable jumping take-off using a tilt and jump approach enables a singly actuated robotic leg to achieve jumping performance similar to birds. A combination of analytical, numerical and physical modelling approaches is used in this study. A generic analytical jumping model is used to establish fundamental understanding of jumping dynamics. The study shows that the take-off dynamics of a jumping system can be idealised as an inelastic collision between the dynamic and static rigid bodies of the system. This provides a simpler way to understand jumping dynamics in general. A physical prismatic jumping model is fabricated principally for validation purposes. A motion capture system is used to quantitatively analyse the jumping kinematics of the model. The take-off velocities predicted through analytical and numerical models agree closely with the experimental data. A multi-segmented numerical simulation model is then developed based on the proposed singly actuated jumping leg design. In the same way an analytical model is developed. It is found that the singly actuated design concept with the assumption of massless segments greatly reduced the complexity of the multi-segmented analytical model. The proposed analytical approach and simulation tool are demonstrated by designing a multi-segmented jumping leg for an example robotic bird. The transparency of the approach enables the designer to understand how design parameters such as take-off weight, actuation properties, leg postures and sizes of the segments affect the take-off velocity. Numerical simulation analysis confirms that jumping performance similar to birds is achieved in the proposed singly actuated jumping legs with the integration of tilt and jump method. For the presented case study, the use of the dynamic tilting method improves the minimum achievable take-off angle from 73° to 12° with respect to the horizontal axis.

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