Vol.1, No 8, 2001 pp. 935 - 938
UDC 621.396.677.7:52-323
ACTIVE VIBRATION ISOLATION AND
POINTING SYSTEM FOR HIGH-PRECISION LARGE DEPLOYABLE
SPACE ANTENNAS
Sayapin Sergei Nicolaevich
Mechanical Engineering Research Institute Russian Academy of Sciences
101830 Moscow, Russia, Fax: (095) 135 61 46; E-mail: vibris@interface.ru
Abstract. The paper is concerned with the problem of providing required
precision parameters of high-precision large deployable space antennas
(HLDSA) small stiffness of antennas entails its high sensitivity to microdinamical
factors arising in the orbital flight. To provide necessary precision of
geometrical characteristics, one have either to diminish microdinamical
factors or to implement active or passive vibration protection systems.
In this paper we concentrate on the second problem. Detailed analysis
has shown that, in condition of orbital flight, the precision parameters
of HLDSA mainly depend on low-frequency vibration with frequencies from
0,01 Hz to 10 Hz and with acceleration magnitude from 0,6 to 10-4 ? 10-6
g. This low frequency vibration is usually induced by external and internal
perturbations. Since the passive vibroprotection is ineffective for low-frequency
vibration, we decide to solwe the problem with help of active vibroprotection
systems.
Comparative analysis of existing and perspective facilities of active
vibration isolation with regards to HLDSA structural features has proved
the effectiveness of active vibroisolation of "the kinematic type". In
this systems an object is attached to the base with actuators controlling
relative position and velosities of the object and of the base via the
information from sensors.
External perturbations leading to reduction of the precision characteristics
may also include structural thermo-deformation. As a result, the antenna's
optical axle deviates from its theoretical position. This requires its
periodic high-precision pointing (up to 1 second of arc) in the real-time
mode.
We present the concepts of the active system of structural control
that provides:
1) vibration isolation of spacecraft from elastic oscillations
of HLDSA, which were caused by its opening on orbit;
2) suppression of oscillations of elastic structure of HLDSA,
which were caused by its opening and external factors;
3) vibroisolation of the structure from microdinamical effects
caused by the functionning of the spacecraft systems;
4) periodic high-precision angular pointing of the HLDSA optical
axis.
AKTIVNA VIBRACIONA IZOLACIJA
I SISTEM PRECIZNOG USMERAVANJA
ZA VELIKE RASKLOPNE ORBITALNE ANTENE
Ovaj rad se bavi problemom obezbeđenja parametara preciznosti za visoko
precizne rasklopive orbitalne antene (HLDSA). Mala krutost antene ukazuje
na visoku osetljivost na mikrodinamičke uticaje u orbiti. U cilju obezbeđenja
preciznosti geometrijskih karakteristika, potrebno je da se umanje mikrodinamički
uticaji ili da se ugrade aktivni ili pasivni sistemi zaštite od vibracija.
U ovom radu mi smo se usredsredili na drugo rešenje. Detaljne analize su
pokazale da u uslovima orbitalnog leta parametri preciznosti za HLDSA uglavnom
zavise od nisko-frekventnih vibracija od 0,01 Hz do 10 Hz sa ubrzanjem
od 104 do 106 g. Ove niskofrekventne vibracije su obično izazvane eksternim
i internim perturbacijama. Pošto je pasivna vibro-zaštita neefektivna za
nisko-frekventne vibracije, mi smo se odlučili da problem rešimo pomoću
sistema krute vibro-zaštite.
