Discounted LQG-based Spiral Scanning Control of a Piezo Actuated Fast Steering Mirror for Space Laser Communication

For the beam scanning stage in space laser communication, an IMLQG controller is proposed to regulate a piezo actuated fast steering mirror (FSM) to track a spiral trajectory in this paper. To achieve a high performance, an internal state transition model is first built to describe such a time sequence command. Then, a linear quadratic regulation (LQR) problem is formulated by augmenting the FSM model with the internal model, which however is not solvable in practice. To this end, a discounted factor is further introduced. Moreover, an adaptive Kalman filter is adopted to estimate the state of FSM with unknown measurement noises. Finally, simulations verify the effectiveness and robustness of our proposed method.