CubeSat Attitude Control Emulation Platform With Three-Axis Gimbal and Helmholtz Cage

Hardware-in-the-loop testing of a satellite's attitude determination and control system is imperative so that the performance of sensors, actuators, and on-board computing can be analyzed prior to launch. Emulation platforms are developed to perform these tests. Magnetically actuated three-axis detumbling emulation is very challenging, due to the requirement of continuous rotation about all three axes and the minimal amount of torque produced by the satellite's magnetorquers. For these reasons, common emulation platforms do not allow for detumbling emulation with magnetorquers. Therefore, a gimbal-based emulation platform is presented in this article that allows for continuous rotation about all three axes and accommodates magnetorquer-based satellite actuation. The system estimates the torque produced by the emulated CubeSat, evolves the attitude of the satellite by numerical integration of Euler's equation, and then dynamically rotates the CubeSat with a motorized three-axis gimbal. A Helmholtz cage is constructed and integrated with the gimbal to control the environmental magnetic field experienced by the emulated CubeSat. The platform is found to effectively emulate the tumbling of a CubeSat in orbit and extend terrestrial attitude emulation capabilities.