Fig. 1. Schematic view of the Tip-Tilt mirror system. (a) Typical configuration of Tip-Tilt mirror system. (b) A typical control structure.

Fig. 2. LQG control structure of Tip-Tilt mirror.

Fig. 3. DFF control structure of Tip-Tilt mirror.

Fig. 4. Conventional DOBC structure of Tip-Tilt mirror.

Fig. 5. Error-based DOBC structure of Tip-Tilt mirror.

Fig. 6. Bode response of the sensitivity function with I and Q_L(s).

Fig. 7. The closed-loop Tip-Tilt errors.

Fig. 8. Spectra of Tip-Tilt vibrations.

Fig. 9. Bode response of Q(s) and ESF(s).

Fig. 10. Spectra of Tip-Tilt vibrations in DOBC mode.

Fig. 11. Bode response of the Eq. (25).

Fig. 12. Bode response of the Eq. (26).

Fig. 13. Sensitivity function responses in frequency domain.

Fig. 14. Tip-Tilt errors in different control modes.

Fig. 15. Spectra of Tip-Tilt vibrations with CRC and IRC.