Boom and Receptacle Autonomous Air Refueling Using a Visual Pressure Snake Optical Sensor

Autonomous in-flight air refueling is an important capability for the future deployment of unmanned air vehicles, since they will likely be ferried in flight to overseas theaters of operation instead of being shipped unassembled in containers. This paper introduces a vision sensor based on active deformable contour algorithms, and a relative navigation system that enables precise and reliable boom and receptacle autonomous air refueling for non micro sized unmanned air vehicles. The sensor is mounted on the tanker aircraft near the boom, and images a single passive target image painted near the refueling receptacle on the receiver aircraft. Controllers are developed for the automatic control of the refueling boom, and for the station keeping controller of the receiver aircraft. The boom controller is integrated with the active deformable contour sensor system, and feasibility of the total system is demonstrated by simulated docking maneuvers in the presence of various levels of turbulence. Results indicate that the integrated sensor and controller enables precise boom and receptacle air refueling, including consideration of realistic measurement errors and disturbances. I

Method and apparatus for controlled omnidirectional movement of payloads

A payload platform includes a platform and a castor assembly coupled to the platform. The castor assembly includes a body, a first wheel coupled to the body, and a second wheel coupled to the body. The first wheel and the second wheel are individually actuatable. A sensor is coupled to the body. A control unit is operably coupled to the sensor and operably coupled to the first wheel and to the second wheel. The sensor detects an area surrounding the platform, determines presence of obstacles, and transmits a signal to the control unit corresponding to the area surrounding the platform. The control unit directs the first wheel and the second wheel to rotate in a prescribed manner so as to achieve a prescribed movement of the platform.U

Mechanism of Substrate and Inhibitor Binding of Rhodobacter capsulatus Xanthine Dehydrogenase*

Rhodobacter capsulatus xanthine dehydrogenase (XDH) is an (αβ)2 heterotetrameric cytoplasmic enzyme that resembles eukaryotic xanthine oxidoreductases in respect to both amino acid sequence and structural fold. To obtain a detailed understanding of the mechanism of substrate and inhibitor binding at the active site, we solved crystal structures of R. capsulatus XDH in the presence of its substrates hypoxanthine, xanthine, and the inhibitor pterin-6-aldehyde using either the inactive desulfo form of the enzyme or an active site mutant (EB232Q) to prevent substrate turnover. The hypoxanthine- and xanthine-bound structures reveal the orientation of both substrates at the active site and show the importance of residue GluB-232 for substrate positioning. The oxygen atom at the C-6 position of both substrates is oriented toward ArgB-310 in the active site. Thus the substrates bind in an orientation opposite to the one seen in the structure of the reduced enzyme with the inhibitor oxypurinol. The tightness of the substrates in the active site suggests that the intermediate products must exit the binding pocket to allow first the attack of the C-2, followed by oxidation of the C-8 atom to form the final product uric acid. Structural studies of pterin-6-aldehyde, a potent inhibitor of R. capsulatus XDH, contribute further to the understanding of the relative positioning of inhibitors and substrates in the binding pocket. Steady state kinetics reveal a competitive inhibition pattern with a Ki of 103.57 ± 18.96 nm for pterin-6-aldehyde