There are benefits to the use of internal actuators for rotational maneuvers of small-scale underwater vehicles. Internal actuators are protected from the outside environment by the external pressure hull and will not disturb the surrounding environment during inspection tasks. Additionally, internal actuators do not rely on the relative fluid motion to exert control moments, therefore they are useful at low speed and in hover. This paper describes the design, fabrication and testing of one such autonomously controlled, internally actuated underwater vehicle. The Internally Actuated, Modular Bodied, Untethered Submersible (IAMBUS) can be used to validate non-linear control strategies using internal actuators. Vehicle attitude control is provided by three orthogonally mounted reaction wheels. The housing is a spherical glass pressure vessel, which contains all of the components, such as actuators, ballast system, power supply, on-board computer and inertial sensor. Since the housing is spherically symmetric, the hydrodynamics of IAMBUS are uncoupled (e.g. a roll maneuver does not impact pitch or yaw). This hull shape enables IAMBUS to be used as a spacecraft attitude dynamics and control simulator with full rotational freedom. / Master of Science

With growing space market and entry of more private companies into the industry, there arecompanies and stakeholders who would like to have a high order of accuracy mission outputrequirements. These requirements vary from mission to mission. This simply means that if acompany wants an Earth observation mission, the main requirement to be fulfilled would be tohave the highest resolution of image possible. In order to achieve this, the satellite carrying the camera payload would be required to bepointed in the right direction with utmost accuracy. For a satellite to be pointed in the rightdirection, the noise generated by the sensors and actuators on-board, which determines theattitude of the satellite and helps in changing it, should be minimized. The aim of this thesisis to design a method which could help in determining the right components to be procuredso that the pointing requirements of the satellite are fulfilled. This objective is achieved bydesigning algorithms in python and MATLAB. The values generated by these algorithms, ultimately describe the type of sensor or actuator to be procured. Finally, the noise generated bysuch individual components act as pointing error source and then PEET is used to translatethese error sources to platform error, to generate a pointing budget and ensure that all pointingrequirements are satisfied.