The NASA Marshall Space Flight Center has developed a synchronized subsystem for use in an automated docking system for docking a chase vehicle with a target vehicle. The chase vehicle is provided with a video camera for feeding digitized frames to an image processing unit, which controls a timing circuit. The timing circuit turns on the video camera to digitize a foreground frame and at the same time turns on a transmitter on the chase vehicle. A power generating antenna on the target vehicle receives the transmitted signal from the transmitter and actuates lights on the chase vehicle so that these lights appear in the foreground frame. After the foreground frame has been grabbed, the timing circuit turns the transmitter off and signals the video camera to digitize a background frame. The image processing unit subtracts the background frame from the foreground frame and provides a docking signal.

Benefits

Potential Commercial Uses

The Technology

The Ternary-Gas Plasma Arc Welding (TGPAW) torch functions by utilizing three gases: a primary inert plasma gas, a secondary inert plasma gas, and an inert shielding gas. The primary inert plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. The second plasma gas is disposed for flow through a longitudinal bore in the electrode. It is directed through the electrode to co-act with the arc to produce equivalent defect free welds in types and thickness of metals (ferrous and non-ferrous) with less total heat input per inch of weld (i.e. less current/voltage output and/or high travel speeds). The completed weld is narrower with greater penetration at any given electrical current setting, thereby producing a more desirable Heat Affected Zone (HAZ) and greater ultimate tensile strength values. In addition, the secondary inert plasma gas compliments the primary inert gas to provide a "stiffer" arc, less subject to becoming skewed and unequal in dimensional shape. This characteristic aids alleviating weld "cutting" defects caused by an asymmetrical arc and subsequent asymmetrical heating pattern at the weld joint. The secondary plasma gas may be any of the inert gases or semi-reactive gases or a mixture of two or more of these, however the choice is dependent on the material being welded and the results desired. The process can be applied to Direct Current Straight Polarity and Variable Polarity Welding Modes. The third inert plasma gas is "shield" gas that is directed through the torch body for circulating around the head of the torch adjacent to the electrode tip. The following diagram illustrates the Ternary Gas system:

Patent Number

6,227,495

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