Designing Nonlinear Robust Controller for Spacecraft Attitude Control Subsystem Simulator

In this paper, the performance of two robust control algorithms, µ-synthesis and high order sliding mode are evaluated on a spacecraft attitude control subsystem simulator as the hardware in the loop. This tabular simulator is placed on a spherical air bearing to validate real-time environment. All actuators and sensors on the platform of spacecraft simulator prepare real conditions as attitude control test bed. Beginning, both designed controllers are simulated by Matlab software, next they are applied on the subsystem. At first, µ-synthesis robust controller is designed for simulator. In this method, weighting matrix are chosen such that the controller becomes robust in combined uncertain condition such as system uncertainties, environmental disturbances and sensor noises. Uncertainty, performance, actuator saturation, disturbance and noise weighting functions are designed based on the dynamics and environmental platform properties. At least high order sliding mode controller based on super twisting algorithm is designed to reduce chattering effects. Contrary to the other second order sliding mode algorithms, in the super twisting method sliding surface derivatives are not used. The Computer and experimental hard ware in the loop simulations are compared together.