Current attempts to build fast, efficient, and maneuverable underwater vehicles have looked to nature for inspiration. However, they have all been based on traditional propulsive techniques, i.e. rotary motors. In the current study a promising and potentially revolutionary approach is taken that overcomes the limitations of these traditional methods-morphing structure concepts with integrated actuation and sensing. Inspiration for this work comes from the manta ray (Manta birostris) and other batoid fish. These creatures are highly maneuverable but are also able to cruise at high speeds over long distances. In this paper, the structural foundation for the biomimetic morphing wing is a tensegrity structure. A preliminary procedure is presented for developing morphing tensegrity structures that include actuating elements. A shape optimization method is used that determines actuator placement and actuation amount necessary to achieve the measured biological displacement field of a ray. Lastly, an experimental manta ray wing is presented that measures the static and dynamic pressure field acting on the ray's wings during a normal flapping cycle.
Tensegrity structures have become of engineering interest in recent years, but very few have found practical use. This lack of integration is attributed to the lack of a well formulated design procedure. In this paper, a preliminary procedure is presented for developing morphing tensegrity structures that include actuating elements. To do this, the virtual work method has been modified to allow for individual actuation of struts and cables. A generalized connectivity matrix for a cantilever beam constructed from either a single 4-strut cell or multiple 4-strut cells has been developed. Global deflections resulting from actuation of specific elements have been calculated. Furthermore, the force density method is expanded to include a necessary upper bound condition such that a physically feasible structure can be designed. Finally, the importance of relative force density values on the overall shape of a structure comprising of multiple unit cells is discussed.
An Orion sounding rocket will be launched from Wallops Flight Facility and will carry a University of Virginia payload to an altitude of 65.7 km to measure the distribution of methane in the Earth’s upper atmosphere and record images and quantitative measurements of the distribution of chlorophyll in the Metompkin Inlet, Virginia. This new payload launch will be UVa’s second launch as a result of a five-year undergraduate design project by a multi-disciplinary student group. As part of a new multi-year design course, undergraduate students designed, built, tested, and will participate in the launch of a suborbital platform from which atmospheric remote sensors and other scientific experiments can operate. The first launch included a simplified atmospheric measurement system intended to demonstrate full system operation and remote sensing capabilities during suborbital flight. The second and upcoming launch includes a methane GFCR system intended for upper atmospheric measurements, a photodiode/camera system intended for the remote sensing of chlorophyll distribution and concentration in the Metompkin Inlet due to confined animal runoff pollution. Two thermoelectrically cooled HgCdTe infrared detectors, with peak sensitivity at 3 mm, were designed to measure the methane distribution in the upper atmosphere, by having infrared radiation filtered through a methane cell and a nitrogen reference cell. A small camera with a green band-pass filter will be aligned with five photodiodes, each covered by a narrow bandpass filter that matches the filters in the SeaWiFS system, to provide cross-referencing for the remote sensing of the chlorophyll in the Metompkin Inlet and to enhance the chlorophyll distribution. This payload will serve as a platform for future atmospheric sensing experiments. Currently, the GFCR has been tested and calibrated, the chlorophyll measurement system is being calibrated, and the components and mounts are being gathered, calibrated, tested and fabricated. In the next few months, the payload will be integrated and the data reduction models will be constructed.