This study is aimed at addressing the practical challenges of conducting hardware-in-the-loop simulation (HILS) for a CubeSat attitude determination and control system (ADCS) with a magnetometer and magnetorquer. The inherent problem of magnetometer time-varying bias is typically addressed using compensation methods. Because compensation is performed in orbit, the application of such methods to HILS is difficult. In addition, the magnetorquer has limited applicability to HILS if only magnetorquers without reaction wheels or control moment gyroscopes are used. In general, HILS for CubeSat uses air bearing; however, it cannot be applied to a solely magnetorquer-based ADCS owing to the inertial moments and center of gravity effects induced by the air bearing table. To overcome these challenges, in this study, the magnetometer reliability is enhanced by compensating for temperature, current, and iron effects, which are modeled experimentally, in the pre-launch stage. Then, a novel single axis-based HILS for CubeSats is developed to minimize the disturbances by the ground environment. The torque limit of the magnetorquer is supplemented through a magnetic field generated by a Helmholtz cage. The proposed HILS environment is mathematically modeled to simulate the performance of the CubeSat ADCS, and its reliability is ensured by comparing the simulation with real-time experimental results. To validate the usefulness of the proposed HILS, it is applied to an ADCS based on a low-cost sensor fusion extended-Kalman filter and a linear quadratic regulator controller commonly used in CubeSats. The simulation and experimental results are well matched, demonstrating the potential of the proposed framework.

SNUGLITE (Seoul National University Global navigation satellite system Laboratory satellITE) is a two-unit cube satellite (CubeSat) with dimensions 10 × 10 × 23 cm that requires an attitude system for missions and ground station telecommunication. A linear-quadratic-Gaussian-based optimal attitude system for the CubeSat platform has been developed using low-cost sensors, with the in-orbit verification of the attitude system being is one of main study objectives. Since launch, the SNUGLITE CubeSat has continuously broadcast in-orbit status information. In this study, a methodology for the analysis of in-orbit attitude estimation results using received data is presented, and this was achieved by comparing two sun-pointing vectors, i.e., the sun-pointing vector calculated using estimated attitude with the positions of the sun and the satellite and the reference vector generated by the power levels of the solar panels. Because the satellite position was required for the attitude analysis, the verification of the performance of the own-developed on-board Global Positioning System (GPS) receiver is also briefly described. Analyses indicate that the attitude estimation of the SNUGLITE CubeSat has achieved an in-orbit real-time pointing accuracy with a root mean square of 6.1°.