A design of a test bed for cubesat attitude determination and control system

Owing to the recent developments in miniaturization and integration technologies, CubeSat's can handle more complex practical missions. Such missions require 3-axis control of the satellite along with a miniaturized 3-axis attitude determination and control systems (ADCS). With the QB0 project, the CubeSat's developed in ITU-SSDTL have also started to use such ADCS systems. Whether they are developed or procured, an ADCS system usually requires a suitable test bed to test the behavior and the performance of it. An ADCS system used for LEO missions usually operates within the Earth's magnetic environments. Therefore magnetic field sensors such as magnetometers are employed to measure the mediums' magnetic field or the change in the magnetic field to determine the orientation and motion of a satellite. Magnetic actuators such as magneto torquers are used to align with the magnetic field of the earth or to damp the tumbling motion of a satellite resulting from unbalanced torque distribution on it. A major goal of the SSDTL is to have such a test bed available in the lab. In addition to related software, the major components are a Helmholtz cage and a suitable air bearing table. With this in mind, the purpose of the present thesis is to aid the development of such an ADCS test bed designing first a suitable Helmholtz Cage system. The sizing of the test system depends on requirements such as the maximum mass of the satellite to be tested, coordinates of center of mass and disturbance levels to be counteracted. In the present thesis, first a comprehensive nanosatellites literature survey is conducted. The success rates and mission failure reasons are also investigated. Based on this preliminary study it is observed that 3U CubeSat's are generally adopted for most missions. Therefore a Helmholtz Cage that will house a 3U CubeSat is considered. A circular Helmholtz cage that will fit a 3U CubeSat is designed and analyzed. 1 axis and 3 axis Helmholtz cage cases are considered. Magnetic field lines present within the cage are demonstrated. Since the size of the Cage considered was just large enough to house 3U the magnetic field lines were not uniform enough. Therefore similar analysis is carried out for larger cage of double the size of the small one. Both are compared for uniformity of the magnetic fields. Then a small square cage is designed and analyzed. Again, 1 axis and 3 axis Helmholtz cage cases are considered. Magnetic field lines present within the cage are demonstrated. The large square cage was found to be the best choice for testing a 3U CubeSat. As a result, a square Helmholtz cage which can be used to test a 3U CubeSat at LEO from 250 km to 1500 km.