turb2.hlp

一个非常好的基于MATLAB的飞机动态控制工具箱,对于从事该方面研究的读者非常有参考价值

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TURB2 is a Simulink subsystem which is contained in the Atmosphe-
ric Turbulence sublibrary of the library WINDLIB. It contains the
Dryden filters UDRYD2, VDRYD2, and WDRYD2 for longitudinal, late-
ral and vertical turbulence, respectively. The filters have been
implemented in masked subsystem blocks, in which the user must
specify the scale lengths Lug, Lvg, and Lwg, and the standard de-
viations sigma_ug, sigma_vg, and sigma_wg.

In TURB2, the coefficients of the Dryden filters vary with the
true airspeed V, which is the INPUTSIGNAL to this subsystem. The
value of the true airspeed must be obtained from the model of the
aircraft under consideration, e.g., V may be extracted from the
outputvector of the system BEAVER, which itself uses the outputs
of TURB2 as inputvector.

In many cases, the variations of V due to atmospheric turbulence
are not very large, and the resulting changes in filter coeffi-
cients may be neglected. In such cases, it is recommended to use
TURB1 in stead of TURB2, thus eliminating the feedback-loop of V
from the aircraft model to TURB2 within the resulting Simulink
system. See TURB1.HLP for more details.

Inputsignal to TURB2:
=====================
  V = true airspeed [m/s]

Outputvector from TURB2:
========================
  uwind = [uw vw ww uwdot vwdot wwdot]',

 (actually, this vector should be called ugust = [ug vg wg ...
 ... ugdot vgdot wgdot]', since the wind velocities and their
 time-derivatives from the subsystem TURB2 are equal to gust
 velocities only; contributions due to WIND(-shear) still have to
 be added to this vector!).

 uw   : wind (gust-) velocity along XB-axis of aircraft [m/s]
 vw   : wind (gust-) velocity along YB-axis of aircraft [m/s]
 ww   : wind (gust-) velocity along ZB-axis of aircraft [m/s]

 uwdot: time-derivative of uw [m/s^2]
 vwdot: time-derivative of vw [m/s^2]
 wwdot: time-derivative of ww [m/s^2]

Parameters which must be set in dialog boxes within TURB2:
==========================================================
Before starting a simulation of a system in which the subsystem
TURB2 is involved, the parameters of the masked subsystem blocks
UDRYD2, VDRYD2, and WDRYD2 have to be defined by double-clicking
these blocks and entering the correct values in their dialog-
boxes. These parameters are:

UDRYD2: Lug     = scale length for longitudinal turbulence [m]
        sigma_ug= standard deviation for longitudinal
                                                  turbulence [m/s]

VDRYD2: Lvg     = scale length for lateral turbulence [m]
        sigma_vg= standard deviation for lateral turbulence [m/s]

WDRYD2: Lwg     = scale length for vertical turbulence [m]
        sigma_wg= standard deviation for vertical turbulence [m/s]

More info:
==========
See UDRYD2.HLP, VDRYD2.HLP, and WDRYD2.HLP for more details about
the masked subsystem blocks from TURB2 (Dryden filters with coef-
ficients that vary with V). More details about Dryden filters with
constant coefficients can be found in the helpfiles TURB1.HLP,
UDRYD1.HLP, VDRYD1.HLP, and WDRYD1.hlp.

See CWIND.HLP and BLWIND.HLP for more information on the imple-
mentation of constant wind and a wind-profile in the Earth's
boundary layer, respectively.

Type WINDLIB to open the Wind & Atmospheric Turbulence Library.

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The FDC toolbox, Copyright Marc Rauw 1994-1998.