Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Huang, Po-Hao Adam

Committee Member/Reader

Huang, Po-Hao Adam

Committee Member/Second Reader

Millett, Paul

Abstract

Cube-Satellites (CubeSats) are nanosatellites composed of cube shaped units, each nominally 10cm to a side and around 1kg in mass. Due to their inherent size and weight limitations, it is often impractical to use conventional attitude, or rotational, control methods such as thrusters on these small satellites. Several methods, including magnetorquer rods and small reaction wheels, are often used instead of traditional methods to work around the size and weight limitations. As a new alternative to these methods, a permanent magnet mounted on a rotatable shaft could be used to achieve attitude control. In much the same way that a compass aligns itself with the Earth’s magnetic field, a permanent magnet mounted on a rotatable shaft could be rotated out of alignment with the magnetic field. The torque generated as the magnet attempts to realign itself could be used to provide rotational control to a CubeSat. Such a system would be significantly lighter than most alternatives and require very little power to operate. In addition, through the use of a 16-bit magnetic encoder, maneuvers with the system would be very precise when target overshoot is compensated for. In the unlikely event of a failure, possibly in the motor providing the rotation, the magnet could be locked in one orientation relative to the satellite. This would result in a constant orientation for the satellite when the stationary magnet aligns itself with Earth’s magnetic field. This problem could be greatly mitigated through the use of a magnetic shield pushed or pulled into place by muscle wire. Once the shield is deployed, backup attitude control systems could be used. The author and another undergraduate honors student have already proven the concept of using a permanent magnet for spacecraft attitude control in 2015. The goal of this research is to advance this concept to a more practical state. These advancements will include the development of a failsafe using a Mu-Metal shield as well as reworking and documenting the testing methods for future researchers.

Keywords

CubeSat; attitude control; fail-safe; Mu-Metal; magnetic shielding; magnetorquer

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