Estudo de um controlador LQT aplicado ao cubesat Sport

Abstract

The present work presents a study for the application of a Linear Quadratic Tracker (LQT), control law for the attitude control of the SPORT mission’s CubeSat. The objective is to computationally implement the control method proposed to the Attitude Determination and Control Subsystem (ADCS) of the mission, to verify its performance against the subsystem’s requirements. Furthermore, the results with the proposed LQT control are compared with the results obtained with the Proportional Integral Derivative (PID) control, the current attitude controller of the SPORT mission. The implementation of the proposed LQT control is done primarily in Simulink, with simplified meshes. After this implementation, the proposed control is added to the simulation of the complete ADCS of the mission, made through Matlab codes. The proposed LQT control is tested in the three main operating modes of the SPORT mission’s ADCS: the nominal mode, the sun pointing mode, and the calibration mode. At the end of the simulations, it is verified that the implementation of the studied control is feasible since it meets the ADCS operation requirements. Furthermore, comparing the results of the proposed LQT control with the current PID control of the mission, it is verified that the LQT control has greater pointing accuracy than the PID control in the nominal and Sun pointing modes, improving the pointing for payload operation and increased energy generation by the solar panels. However, with the LQT control design used in this work, to obtain this greater pointing accuracy, the controller requires more energy from the reaction wheels.