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Description:
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Spacecraft missions such as spacecraft docking and formation flying require high precision relative position and attitude data . Although Global Positioining Systems can provide this capability near the earth , deep space missions require the use of alternative technologies . One such technology is the vision -based navigation (VISNAV ) sensor system developed at Texas A &M University . VISNAV comprises an electro -optical sensor combined with light sources or beacons . This patented sensor has an analog detector in the focal plane with a rise time of a few microseconds . Accuracies better than one part in 2000 of the field of view have been obtained . This research presents a new approach involving simultaneous activation of beacons with frequency division multiplexing as part of the VISNAV sensor system . In addition , it discusses the synchronous demodulation process using digital heterodyning and decimating filter banks on a low -power fixed point DSP , which improves the accuracy of the sensor measurements and the reliability of the system . This research also presents an optimal and computationally efficient six -degree -of -freedom estimation algorithm using a new measurement model based on the attitude representation of Modified Rodrigues Parameters . |