Design and Demonstration of a Two-Dimentional Test Bed for UAV Controller Evaluation

A three degree-of-freedom (DOF) planar test bed for Unmanned Aerial Vehicle (UAV) controller evaluation was built. The test-bed consists of an instrumented tether and an experimental twin-rotor, planar UAV mounted with a one DOF manipulator mounted below the UAV body. The tether was constructed to constrain the UAV under test to motion on the surface of a sphere. Experiments can be conducted through the tether, approximating motion in a vertical plane by a UAV under test. The tether provides the means to measure the position and attitude of the UAV under test. The experimental twin-rotor UAV and one-link on-board manipulator, were designed and built to explore a unified control strategy for Manipulator on VTOL Aircraft (MOVA), in which the interaction of UAV body dynamics with the manipulator motion is of primary interest. The dynamics of the propulsion unit was characterized through experiments, based on which a phase lead compensator was designed to improve the UAV frequency response. A \u27separate\u27 controller based on independent nonlinear control of the VTOL aircraft and PD linear control of the on-board manipulator was designed as a reference for comparison to the unified MOVA controller. Tests with the separate controller show the negative effect that a coupled manipulator can have on the UAV body motion, while the tests on MOVA show the potential benefit of explicit compensation of the UAV and manipulator interaction

Thermodynamics of Ising Antiferromagnets with Phantom Cross-link Network on Husimi Lattice

A second order cross-linked network is applied onto the classical Husimi lattice, to investigate the role of a "phantom" non-neighboring interactions of mid- and long-range in Bethe-like lattices for the first time. Since antiferromagnetic Ising model on Husimi lattice has been exactly solved and successfully presented the melting and glass transition, the Phantom Cross-link Network (PCN) is introduced here to understand the relationship between glassy defect and long-range interactions in small molecule systems, and the concept is inspired from the classical rubber network theory (Flory, 1985). One random site out of four on the recursive unites with certain distance I (the net size) is selected to be linked onto the PCN. The solutions are still in the fashion of normal antiferromagnetic Ising model, with expected frustrations along with the net size I. Beside the regular Curie transition, several interesting thermodynamics are observed in this toy model, and as the main found, PCN clearly introduces glassy portion into the system, identified by the supercooling behavior with lower TC, the metastable entropy curve and the Kauzmann paradox.Comment: 6 pages, 3 figures, 1 tabl