Investigation of Gain Tuning and Sensor Noise for CubeSat B-dot Detumbling and 3-axis PD Magnetic Attitude Control

Abstract

This paper carries out an iterative computer simulation approach to tune B-dot detumbling and 3-axis PD attitude controller gains for magnetically-actuated CubeSats. The effect of different gains for 1U and 2U CubeSats are investigated along with the effect on PD control performance when nonidealities are included in the simulator such as Sun sensor noise, magnetometer sensor noise, rate gyroscope sensor noise and CubeSat eclipse conditions (when the Satellite cannot estimate its attitude using Sun sensors due to Earth blocking Sun). For the simulation conditions used in this research, it was observed that a relatively large range of B-dot gain values (between 2 × 10 3 and 1 × 10 5 A 2 s 3 m 2 /rad-kg) enables both 1U and 2U CubeSats to settle in under ~10 orbits, indicating a degree of insensitivity to the gains selected for a B-dot controller. Compared to the B-dot detumbling controller, the 3axis PD magnetic attitude controller was found to be more sensitive to CubeSat geometry and control gain selection with some gains resulting in significant settling times and others yielding ineffective attitude control. It was also observed that the presence of sensor noise increased settling time and steadystate oscillations in attitude and angular rate errors, while the presence of eclipse conditions showed similar settling times and steady-state behaviour to the non-eclipse cases.