ils.hlp

MATLAB在飞行动力学和控制中应用的工具

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The masked subsystem block ILS, which is contained in the library
NAVLIB, is used to compute nominal values of the glideslope and
localizer signals, for a given position of the aircraft. Also,
the validity of the signals is checked (see ILSTEST.HLP). See
the FDC 1.2 manual, or ref.[1] for more details about the defi-
nitions of the different variables and parameters.

Inputvector:
============
  uils = [xe ye H]'

where:

  xe: X-coordinate of aircraft in Earth-axes, [m]
  ye: Y-coordinate of aircraft in Earth-axes, [m]
  H : altitude of aircraft above sea level, [m]

These inputvariables are OUTPUTS from a NONLINEAR aircraft model.
The block ILS, which computes the nominal values of the ILS sig-
nals, does not give correct results if a small-deviations model
is used for the aircraft dynamics! Open the system BEAVER for
an example of such a nonlinear aircraft model!

Outputvectors:
==============
  yils1 = [igs iloc]'
  yils2 = [epsilon_gs Gamma_loc]'
  yils3 = [xf yf Hf dgs Rgs Rloc]'
  yils4 = [LOC_flag GS_flag]'

where:

  igs       : nominal localizer current, [鍭]
  iloc      : nominal glideslope current, [鍭]

  epsilon_gs: angle between line through aircraft's c.g. and
              glideslope antenna and nominal glide path, [rad]
  Gamma_loc : angle between ground-projection of line through
              aircraft's c.g. and localizer antenna, and runway
              centerline, [rad]

  xf        : X-coordinate of aircraft in runway-fixed reference
              frame XF-YF-ZF, [m]
  yf        : Y-coordinate of aircraft in runway-fixed reference
              frame XF-YF-ZF, [m]
  Hf        : altitude of aircraft in runway-fixed reference
              frame XF-YF-ZF, [m]; Hf = -zf
  dgs       : distance from aircraft's c.g. to nominal glide path,
              measured perpendicularly to nominal glide path, [m]
  Rgs       : 2D-distance from c.g. of aircraft to glideslope an-
              tenna (as seen from above), [m]
  Rloc      : 2D-distance from c.g. of aircraft to localizer an-
              tenna (as seen from above), [m]

  LOC_flag  : flag which is set to one if localizer signal cannot
              be received with appropriate accuracy, else,
              LOC_flag = 0
  GS_flag   : flag which is set to one if glideslope signal can-
              not be received with appropriate accuracy, else,
              GS_flag = 0

igs is proportional to epsilon_gs, iloc is proportional to
Gamma_loc. Both igs and iloc are limited to +/- 150 [鍭]. For
more info about the definitions of the variables, consult ref.[1]
or the FDC 1.2 user-manual.

Parameters which need to be specified in dialog-boxes of masked
subsystem ILS:
===============================================================
* position of the origin of the runway-fixed reference frame XF-
  YF-ZF (given by the coordinates XRW, YRW, and altitude above
  sea level HRW; all measured relatively to Earth-fixed reference
  frame)

* heading of the runway, psi_RW

* nominal glideslope angle, gamma_gs

* X-distance from runway threshold to localizer antenna, x_loc

* X-distance from runway threshold to glideslope antenna, x_gs

* Y-distance from runway centerline to glideslope antenna, y_gs

Double-click ILS to specify these variables (units of measure-
ments are given in dialog-boxes).

References:
===========
[1]. Rauw, M.O. A Simulink environment for Flight Dynamics and
     Control analysis - Application to the DHC-2 'Beaver'
     (2 parts). Graduate's thesis, Delft University of Technology
     (Aerospace Engineering), Delft, September 1993.

More info.
==========
See GSERR.HLP and LOCERR.HLP for more info on steady-state errors
in the glideslope and localizer currents, respectively. See
GSNOISE.HLP and LOCNOISE.HLP for more info on noise in glideslope
and localizer currents, respectively.

An example of the practical use of the ILS and VOR blocks can be
found in the 'Beaver' autopilot simulation model APILOT2. In that
system, only nominal signals are considered; however, it is possi-
ble to replace the ILS-block from APILOT2 by the system 'ILS exam-
ple' from NAVLIB. See APILOT.HLP for more info.

See also ILSXMPL.HLP (helptext for subsystem 'ILS example' from
the NAVLIB library).

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The FDC toolbox, Copyright Marc Rauw 1994-1998.