Kalman Filtering for Spacecraft Attitude Estimation by Low-Cost Sensors

Abstract

Recently, small satellites have entered a new era initiated by several university programs of space research exploration. Some universities have been designing nanosatellite weight class under very tight budget constraints, some universities have the challenge of designing a small scale spacecraft with specific science missions for exploration to the moon, asteroid or other planets. Since these programs are initially defined by universities, several limitations exist. The constraints may be divided by three categories : prices, weight and power. As a result, the sensor suites of the small satellites are comprised of less accurate low cost component with little heritage. The mass and constraints also discouraged the use of accurate or redundant sensors. [1] As available sensors for spacecraft attitude determination (AD), there are several useful AD sensors. The three-axis magnetometer(TAM) is an imperative part. [2] TAM gives a continuously available two-axis attitude measurement. Even though this AD sensor is relatively low-cost element, it gives surprising accuracy. Therefore, almost every attitude controlled spacecraft has included one type of TAM. Other acceptable AD sensors for small satellites are sun and star trackers. Sun sensors based on small CMOS cameras have been developed and offer the inspiring prospect of sub-degree pointing accuracy. The CMOS star tracker is the ultimate want list of a small satellite for attitude determination.