The ITASAT CubeSat Development and Design

Valdemir Carrara,Rafael Barbosa Januzi,Luis Felipe De Paula Santos,Lidia Shibuya Sato,Daniel Hideaki Makita

doi:10.5028/jatm.v9i2.614

Abstract

Because they are inexpensive platforms for satellites, CubeSats have become a low-cost way for universities and even developing countries to have access to space technology. This paper presents the ITASAT design, particularly the Attitude Determination and Control Subsystem, the Onboard Software, and the Assembly,Integration and Testing program. The ITASAT is a 6U CubeSat nano-satellite in development at the Instituto Tecnologico de Aeronautica, in Sao Jose dos Campos, Brazil. The platform and its subsystems will be provided by industry while the payloads are being designed and developed by the principal investigators. The ITASAT Attitude Determination and Control Subsystem will rely on a 3-axis magnetometer, 6 analog cosine sun sensors, 3-axis MEMS gyroscopes, 3 magnetic torque coils, and 3 reaction wheels. The Attitude Determination and Control Subsystem operating modes, control laws, and embedded software are under the responsibility of the Instituto Tecnologico de Aeronautica. A Kalman filter shall be employed to estimate the quaternion attitude and gyroscope biases from sensor measurements. The Attitude Determination and Control Subsystem operating modes are the nominal mode, with geocentric pointing attitude control and the stabilization mode, in which only the satellite angular velocity is controlled. The nominal mode will be split into 2 sub-modes: reaction wheel control plus magnetic wheel desaturation and 3-axis magnetic attitude control. Simulation results have shown that the attitude can be controlled with 1-degree accuracy in nominal mode with the reaction wheels, but these errors grow as much as 20 degrees or higher with the 3-axis magnetic control.

Highlights

CubeSat platforms use Commercial Off-The-Shelf (COTS) components that cost tenths of the expensive radiation-resistant and space qualified components
The main objective of this paper is to present the current status of the ITASAT design, on the Assembly, Integration and Testing (AIT) program and the Attitude Determination Control System (ADCS), which is the most complex subsystem on the satellite
The ITASAT project is being carried out by university students with funds provided by the Brazilian Space Agency (AEB)

Summary

Introduction

CubeSat platforms use Commercial Off-The-Shelf (COTS) components that cost tenths of the expensive radiation-resistant and space qualified components. The Rate Reduction algorithm is similar to the B-dot, except that it takes directly the satellite’s angular rate as measured by the gyroscope, instead of the time derivative of the geomagnetic field, to compute the magnetic moment to be applied to the MT: Both modes were simulated in MATLAB with the PROPAT Toolbox (Carrara 2015), and gave similar results. The RW controller, CRW, computes the attitude error in Euler angles from the attitude quaternion q with respect to the reference attitude, besides the satellite angular velocity with respect to the orbital frame, and applies them to a conventional PD controller, which, in turn, commands the torque to the reaction wheels.

X: Yaw Y: Roll

Findings

Conclusions