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Description
This report represents aerospace mechanics and controls for CubeSats, quadcopters and aircraft. A CubeSAT is a small satellite on the order of 10 centimeters along each axis. A 1U satellite is a small cube with 10 cm sides. These satellites are used for a variety of missions and created by a variety of different organizations. When deployed from a rocket, a CubeSAT may obtain a large angular velocity which must be reduced before most science missions or communications can take place. Maximizing solar energy charging also involves better pointing accuracy. To control the attitude of these small satellites, reaction wheels, magnetorquers and even the gravity gradient are used in low earth orbit (LEO) while reaction control thrusters are typically used in deep space. On a standard LEO CubeSAT, 3 reaction wheels are used as well as 3 magnetorquers. In the initial phase of the CubeSAT mission, the magnetorquers are used to reduce the angular velocity of the satellite down to a manageable level. Once the norm of the angular velocity is low enough, the reaction wheels can spin up reducing the angular velocity to zero. At this point a Sun finding algorithm is employed to find the Sun and fully charge the batteries. In LEO two independent vectors are obtained, the Sun vector and the magnetic field vector, to determine the current attitude of the vehicle which is typically called attitude determination. Other sensors such as horizon sensors, star trackers and even lunar sensors can be used to obtain the quaternion of the vehicle. This paper investigates the necessary mathematics to understand the intricacies of guidance, navigation and control specifically discussing the attitude determination and controls subsystem (ADACS).
Publication Date
Fall 9-30-2021
Disciplines
Aerospace Engineering
Recommended Citation
Montalvo, Carlos, "Aerospace Mechanics and Controls" (2021). Textbooks. 2.
https://jagworks.southalabama.edu/southalabama-oer-engineer-textbook/2
Comments
This report represents aerospace mechanics and controls for CubeSats, quadcopters and aircraft. A CubeSAT is a small satellite on the order of 10 centimeters along each axis. A 1U satellite is a small cube with 10 cm sides. These satellites are used for a variety of missions and created by a variety of different organizations. When deployed from a rocket, a CubeSAT may obtain a large angular velocity which must be reduced before most science missions or communications can take place. Maximizing solar energy charging also involves better pointing accuracy. To control the attitude of these small satellites, reaction wheels, magnetorquers and even the gravity gradient are used in low earth orbit (LEO) while reaction control thrusters are typically used in deep space. On a standard LEO CubeSAT, 3 reaction wheels are used as well as 3 magnetorquers. In the initial phase of the CubeSAT mission, the magnetorquers are used to reduce the angular velocity of the satellite down to a manageable level. Once the norm of the angular velocity is low enough, the reaction wheels can spin up reducing the angular velocity to zero. At this point a Sun finding algorithm is employed to find the Sun and fully charge the batteries. In LEO two independent vectors are obtained, the Sun vector and the magnetic field vector, to determine the current attitude of the vehicle which is typically called attitude determination. Other sensors such as horizon sensors, star trackers and even lunar sensors can be used to obtain the quaternion of the vehicle. This paper investigates the necessary mathematics to understand the intricacies of guidance, navigation and control specifically discussing the attitude determination and controls subsystem (ADACS).