A document describes a system to reliably gather the hang-angle inclination of the orbiter. The system comprises a wireless handheld master station (which contains the main station software) and a wireless remote station (which contains the inclinometer sensors, the RF transceivers, and the remote station software). The remote station is designed to provide redundancy to the system. It includes two RF transceivers, two power-management boards, and four inclinometer sensors.

Power-management algorithms were developed and implemented to assure nominal system operation over the elapsed time between when the inclinometer system is installed at the orbiter processing facility (OPF), and the actual hang-angle measurement operation when the orbiter is brought up to a full vertical position in the vehicle assembly building (VAB). Relay and polling schemes were implemented to overcome any RF interference and power-management schemes, respectively. A set of unique algorithms was also developed to take full advantage of the redundancy of the system to meet the critical measurement requirements.

Several novel features of the wireless hang-angle inclinometer system are an ultra-low thermal expansion coefficient mounting bracket, housing the inclinometer sensors, to minimize errors caused by thermal expansion over the wide temperature range; a power management software to monitor and conserve electrical energy of the batteries in the remote station; and an RF health check algorithm to verify/assure proper communication link between the remote station and the hand-held base station.

This work was done by Angel Lucena, Jose Perotti, Eric Green, and Jonathan Byon of Kennedy Space Center; Bradley Burns, Carlos Mata, and John Randazzo of ASRC Aerospace Corporation; and Norman Blalock of Sierra Lobo, Inc. KSC-12751

NASA Tech Briefs Magazine

This article first appeared in the April, 2011 issue of NASA Tech Briefs Magazine.

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