Automatic Mass Balancing of Spacecraft Attitude Simulator by Parameter Estimation and Linear Control

In order to perform attitude control ground experiments, it is crucial to ensure the center of mass of the platform is coincident with the center of rotation as accurate as possible. In this paper, a linearized dynamic model of the imbalanced attitude platform is derived and a linear controller is methodically designed to stabilize the system by mass relocation. The stability conditions of the system under the proposed controller are derived. The balancing procedure starts with a parameter estimation method to estimate the center of mass offsets. Next, the PD controller is applied to align the platform’s horizontal plane with the local horizontal level. Finally, the imbalance in vertical axis can be estimated and compensated to complete the automatic mass balancing. Actuator limitations and nonlinear equations of motion are implemented in numerical simulations and the results demonstrate the effectiveness of the proposed method in significantly reducing the residual imbalance torque on the simulated platform.