Error-Frame Representation for Spacecraft Visual Relative Navigation

Relative navigation of spacecraft has been an area of active research since the Apollo era. nbsp;Optical sensor systems offer a distinct advantage for spacecraft relative navigation applications by collecting passive data to be used as measurement updates; however, these systems often require large databases of feature locations on the deputy spacecraft and a communication link to retrieve IMU data from the deputy spacecraft.nbsp;The central objective of the proposed technology is the development of a spacecraft relative navigation system that is capable of using an arbitrary non-cooperative object as the deputy spacecraft without the need of training trials. nbsp;The technology consists of a novel sensor, called VISNAV, an IMU and computational hardware. nbsp;During Phase I, the actual relative navigation algorithms will be developed. nbsp;The algorithms will consist of extracting feature information from the images collected by the optical sensor. nbsp;This feature information will be utilized for determining rate information of the deputy vehicle through an optical flow technique. nbsp;It will also be used for measurement updates in a newly derived filter, called the geometric extended Kalman filter, which provides physically consistent estimates, unlike all existing filter formulations. nbsp;Finally, a multiple hypothesis tracking algorithm will be used to compare the expected feature locations from the filter to the ones measured in the images. nbsp;This will ensure that the features are accurately tracked over time, thus eliminating the need to train the system or rely on a communication datalink.nbsp;It is expected that at the completion of Phase I the navigation algorithms will be derived and verified through simulation testing as well as hardware in the loop testing within a realistic test environment. nbsp;This initial testing and hardware configuration will be used to expedite prototyping and system tests to be conducted during Phase II.