In-Space Spacecraft Alignment Calibration Using the Unscented Filter

A new spacecraft sensor alignment estimation approach based on the Unscented filter is derived. Basic six-state attitude estimation is widely implemented in actual spacecraft missions. However, more stringent spacecraft pointing accuracy requires sensor alignment calibration to be performed post-launch to accommodate in-space disturbances and launch shock vibration. Sequential filtering is preferred since the calibration parameters could drift over time. It also minimizes ground crew intervention and mission disruption. Simulated spacecraft data results shows that the Unscented filter is more robust and more suitable for on-board implementation than the traditional extended Kalman filter. Also, experimental results from the Microwave Anisotropy Probe using the Unscented filter are shown to test the performance of the algorithm using real data.