Automatic Mass Balancing of a Small Spherical Simulator for Attitude Control Verification

In the aerospace field, researchers and engineers have been using attitude simulators to test and evaluate spacecraft attitude control algorithms, usually developed at the design stage. Moreover, thanks to the new technological achievements, small satellites can include more complex algorithms in their attitude determination and control systems. In consequence, the development of an attitude simulator that is able to perform different control algorithms with high attitude accuracy and stability is in high demand. In this paper, an automatic balancing method, along with a modified Model Reference Adaptive Control architecture for an uncertain dynamical system with unknown perturbation, was developed to address uncertainty suppression and disturbance rejection for an air-bearing spherical attitude simulator. The main feature of the proposed scheme consists of obtaining estimates of the offset vector generated by an unbalanced mass system in order to reduce it by moving small masses along each principal axis, ensuring stability and improving motion performance with an adaptive controller with input error modification. Simulation results were conducted according to the parameters for a small satellite 1U-class CubeSat platform inside a spherical structure.