A Gradient Estimation Scheme of an External Unknown Torque on a Satellite

Inherent among newly developed "plug and play" satellites will be errors in measurement and placement of the devices-sensors and actuators-on the satellite. Other uncertainties also arise due to the unprecise nature of plug and play (PNP) satellites. One of these uncertainties is the body frame to the orbit frame transformation. Not knowing this transformation makes it difficult to accurately model the gravity gradient's influence on the satellite. An adaptive algorithm for the gravity gradient estimation problem is presented.