• Opto-Electronic Advances
  • Vol. 2, Issue 10, 190011 (2019)
Tao Tang1、2, Shuaixu Niu1、2、3, Jiaguang Ma1、2, Bo Qi1、2、*, Ge Ren1、2, and Yongmei Huang1、2
Author Affiliations
  • 1Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
  • 2Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China
  • 3University of Chinese Academy of Sciences, Beijing 100049, China
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    DOI: 10.29026/oea.2019.190011 Cite this Article
    Tao Tang, Shuaixu Niu, Jiaguang Ma, Bo Qi, Ge Ren, Yongmei Huang. A review on control methodologies of disturbance rejections in optical telescope[J]. Opto-Electronic Advances, 2019, 2(10): 190011 Copy Citation Text show less

    Abstract

    Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes. In this paper, the state of art control methods—proportional integral (PI) control, linear quadratic Gaussian (LQG) control, disturbance feed forward (DFF) control, and disturbance observer control (DOBC) of Tip-Tilt mirror to reject vibrations are first reviewed, and then compared systematically and comprehensively. Some mathematical transformations allow PI, LQG, DFF, and DOBC to be described in a uniform framework of sensitivity function that expresses their advantages and disadvantages. In essence, feed forward control based-inverse model is the main idea of current techniques, which is dependent on accuracies of models in terms of Tip-Tilt mirror and vibrations. DOBC can relax dependences on accuracy model, and therefore this survey concentrates on concise tutorials of this method with clear descriptions of their features in the control area of disturbance rejections. Its applications in various conditions are reviewed with emphasis on the effectiveness. Finally, the open problems, challenges and research prospects of DOBC of Tip-Tilt mirror are discussed.
    $ {S'_R}(s) = \frac{{E(s)}}{{R(s)}} = \frac{1}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}}}}, $ (1)

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    $ {S'_D}(s) = \frac{{Y(s)}}{{D(s)}} = \frac{1}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}}}}, $ (2)

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    $ G(s) = \frac{1}{{\frac{{{s^2}}}{{\omega _n^2}} + 2\frac{\xi }{{{\omega _n}}}s + 1}}\frac{1}{{{T_{\rm{e}}}s + 1}}. $ (3)

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    $ \left\{ \begin{array}{l} \arg [P({\rm{j}}{w_{\rm{c}}})] \ge \frac{{\rm{ \mathsf{ π} }}}{4}\;, \;\;\;\;\;\;\;\;\;\;\;\;\left| {P({\rm{j}}{w_{\rm{c}}})} \right| = 1\\ - 20\lg \left| {P({\rm{j}}{w_{\rm{g}}})} \right| \ge 6\;, \;\;\;\arg [P({\rm{j}}{w_{\rm{g}}})] = - {\rm{ \mathsf{ π} }} \end{array} \right.. $ (4)

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    $ C(s) = \frac{{\rm{ \mathsf{ π} }}}{{4\tau }}\frac{{{T_{\rm{e}}}s + 1}}{s}. $ (5)

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    $ \hat S \approx \frac{1}{{1 + \frac{{\rm{ \mathsf{ π} }}}{{4\tau }}\frac{1}{s}{{\rm{e}}^{ - \tau s}}}}. $ (6)

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    $ Y(s) = \frac{{C(s)G(s){{\rm{e}}^{ - \tau s}}}}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}}}}R(s) + \frac{{1 - DFF(s)G(s)}}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}}}}D(s). $ (7)

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    $ DFF(s) = \frac{1}{{G(s)}}. $ (8)

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    $ {S_R}(s) = \frac{{1 - Q(s)}}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}} + ({{\rm{e}}^{ - \tau s}}G(s)G_m^{ - 1}(s) - 1)Q(s)}} $ (9)

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    $ {S_D}(s) = \frac{{1 - Q(s)}}{{1 + C(s)G(s){{\rm{e}}^{ - \tau s}} + ({{\rm{e}}^{ - \tau s}}G(s)G_m^{ - 1}(s) - 1)Q(s)}}. $ (10)

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    $ \begin{array}{l} W(s) = 1 + {{\rm{e}}^{ - \eta s}}C(s)\;G(s) + \left( {G_m^{ - 1}(s)\;G(s) - 1} \right)Q(s)\\ \;\;\;\;\;\;\;\; = \left( {1 + {{\rm{e}}^{ - \eta s}}C(s)\;G(s)} \right)\left( {1 + \frac{{\left( {G_m^{ - 1}(s)\;G(s) - 1} \right)Q(s)}}{{1 + {{\rm{e}}^{ - \eta s}}C(s)\;G(s)}}} \right), \end{array} $ (11)

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    $ {\left\| {\frac{{\left( {G_m^{ - 1}(s)\;G(s) - 1} \right)\;Q(s)}}{{1 + {{\rm{e}}^{ - \eta s}}C(s)\;G(s)}}} \right\|_\infty } < 1. $ (12)

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    $ {Q_{\rm{L}}}(s) = \frac{{\sum\limits_{k = 2}^{m - 2} {C_m^k(} \tau s{)^k} + 1}}{{{{(\tau s + 1)}^m}}}. $ (13)

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    $ 1 - Q(s)]D(s) = 0. $ (14)

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    $ D(s) = {A_i}\sum\limits_{i = 0}^k {\varphi (s, {w_i})} , $ (15)

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    $ 1 - Q(s)]D(s) = \prod\limits_{i = 1}^k {(\frac{{{s^2}}}{{w_i^2}} + 1)} D(s) = 0. $ (16)

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    $ ESF(s) = 1 - Q(s) = \prod\limits_{i = 1}^k {\frac{{\frac{{{s^2}}}{{w_i^2}} + {\zeta _i}\frac{s}{{{w_i}}} + 1}}{{\frac{{{s^2}}}{{w_i^2}} + {\alpha _i}{\zeta _i}\frac{s}{{{w_i}}} + {\beta _i}}}} , $ (17)

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    $ \begin{array}{l} Q(s) = 1 - \prod\limits_{i = 1}^k {\frac{{\frac{{{s^2}}}{{w_i^2}} + {\zeta _i}\frac{s}{{{w_i}}} + 1}}{{\frac{{{s^2}}}{{w_i^2}} + {\alpha _i}{\zeta _i}\frac{s}{{{w_i}}} + 1}}} \\ \;\;\;\;\;\;\; = \frac{{\prod\limits_{i = 1}^k {\left( {\frac{{{s^2}}}{{w_i^2}} + {\alpha _i}{\zeta _i}\frac{s}{{{w_i}}} + 1} \right)} - \prod\limits_{i = 1}^k {\left( {\frac{{{s^2}}}{{w_i^2}} + {\zeta _i}\frac{s}{{{w_i}}} + 1} \right)} }}{{\prod\limits_{i = 1}^k {\left( {\frac{{{s^2}}}{{w_i^2}} + {\alpha _i}{\zeta _i}\frac{s}{{{w_i}}} + 1} \right)} }}. \end{array} $ (18)

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    $ ESF(s) = ES{F_1}(s) \times ES{F_2}(s) \times ES{F_3}(s), $ (19)

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    $ {\rm{Where,}}\;ES{F_1}(s) = \frac{{0.000659{s^2} + 2.567{\rm{e}} - 5s + 1}}{{0.000659{s^2} + 0.0154s + 1}}, $ (20)

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    $ ES{F_2}(s) = \frac{{2.093{\rm{e}} - 4{s^2} + 1.447{\rm{e}} - 5s + 1}}{{2.093{\rm{e}} - 4{s^2} + 0.002894s + 1}}, $ (21)

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    $ ES{F_3}(s) = \frac{{5.234{\mathop{\rm e}\nolimits} - 5{s^2} + 7.234{\rm{e}} - 6s + 1}}{{5.234{\rm{e}} - 5{s^2} + 7.234{\rm{e}} - 4s + 1}}. $ (22)

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    $ {Q_{{\rm{CRC}}}}({{\rm{e}}^{ - sT}}) = {{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l). $ (23)

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    $ \begin{array}{l} q({{\rm{e}}^{ - sT}}, l) = {a_l}{{\rm{e}}^{slT}} + {a_{l - 1}}{{\rm{e}}^{s(l - 1)T}} + \cdots {a_0} + \cdots \\ \;\;\;\;\;\;\;\;\;\;\;\; + {a_{l - 1}}{e^{ - s(l - 1)T}} + {a_l}{e^{ - slT}}, \end{array} $ (24)

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    $ {E_{{\rm{CRC}}}}({{\rm{e}}^{ - sT}}) = 1 - {{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l). $ (25)

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    $ {E_{{\rm{IRC}}}}({{\rm{e}}^{ - sT}}) = \frac{{1 - {{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l)}}{{1 - \alpha {{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l)}}\;, \;\;\;\alpha \in [0, 1]. $ (26)

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    $ {\left| {{E_{{\rm{IRC}}}}({{\rm{e}}^{ - sT}})} \right|^2} = \frac{{2 - 2\cos (w/N)}}{{1 + {\alpha ^2} - 2\alpha \cos (w/N)}}. $ (27)

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    $ \begin{array}{l} {Q_{{\rm{IRC}}}}({{\rm{e}}^{ - sT}}) = 1 - {E_{{\rm{IRC}}}}({{\rm{e}}^{ - sT}})\\ \;\;\;\;\;\;\;\;\;\;\;\;\;\;\; = \frac{{(1 - \alpha ){{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l)}}{{1 - \alpha {{\rm{e}}^{ - sNT}}q({{\rm{e}}^{ - sT}}, l)}}. \end{array} $ (28)

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    Tao Tang, Shuaixu Niu, Jiaguang Ma, Bo Qi, Ge Ren, Yongmei Huang. A review on control methodologies of disturbance rejections in optical telescope[J]. Opto-Electronic Advances, 2019, 2(10): 190011
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