vabdot.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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VABDOT is a masked Simulink subsystem which is used to compute
time-derivatives of the true airspeed, angle of attack, and side-
slip angle. It is contained in the sub-subsystem '12 ODEs' of
the subsystem 'Aircraft Equations of Motion' of the S-function
BEAVER.

Note: the time-derivative of the sideslip angle beta which leaves
VABDOT does not yet take into account the influence of beta-dot
itself upon the aerodynamic force along the YB-axis. This contri-
bution was neglected in the block AEROMOD and has therefore not
been included in the force Fy from the inputvector Ftot, used by
VABDOT. The resulting error to the time-derivative of the state
vector, xdot, is corrected later in the block XDOTCORR (see
XDOTCORR.HLP and EQMOTION.HLP for more details).

Inputvector: uvab (the inputvariables which are not used in
VABDOT are displayed between brackets).
===========================================================
  uvab = [x' Ftot' Mtot' yhlp'],

  x    = [V alpha beta p q r psi theta phi xe ye H]'     (states)

  Ftot = [Fx Fy Fz]'           (total forces along the body-axes,
                                    computed in the block FMDIMS)

  Mtot = [L M N]'             (total moments along the body-axes,
                                    computed in the block FMDIMS)

  yhlp = [cos(alpha) sin(alpha) cos(beta) sin(beta) ...
          ... tan(beta) sin(psi) cos(psi) sin(theta) ...
          ... cos(theta) sin(phi) cos(phi)]'
            (frequently used sines & cosines, coming from HLPFCN)

where:

  V    : airspeed [m/s]
 {alpha: angle of attack [rad]                                  }
 {beta : sideslip angle [rad]                                   }
  p    : roll rate [rad/s]
  q    : pitch rate [rad/s]
  r    : yaw rate [rad/s]
 {psi  : yaw angle [rad]                                        }
 {theta: pitch angle [rad]                                      }
 {phi  : roll angle [rad]                                       }
 {xe   : x-coordinate in Earth-fixed reference frame [m]        }
 {ye   : y-coordinate ''     ''          ''      ''  [m]        }
 {H    : altitude above sea-level [m]                           }

  Fx, Fy, Fz: total forces along the aircraft's body-axes [N]
 {L, M, N   : total moments along the aircraft's body-axes [Nm] }

  of the inputvector yhlp, cos(alpha), cos(beta), sin(alpha),
  sin(beta), and tan(beta) are used.

Outputvector: yvab.
===================
  yvab = [Vdot alphadot betadot]'

where:

  Vdot    : dV/dt [m/s^2]
  alphadot: d(alpha)/dt [rad/s^2]
  betadot : d(beta)/dt [rad/s^2]

  Note: the beta-dot equation in VABDOT does not take into
  account the contribution of beta-dot itself to the sideforce
  Fy. Corrections are made in XDOTCORR.

Parameters which must be loaded in the Matlab Workspace.
========================================================
  GM1 = vector with some important geometrical properties of the
        'Beaver' aircraft, and the mass of the aircraft (which is
        assumed to be constant during the motions of interest).
        Here, the mass of the aircraft is extracted from GM1. GM1
        can be loaded into the Matlab workspace by calling the
        M-file LOADER.M, or, if the necessary datafile with
        aircraft model parameters does not yet exist, MODBUILD.M.
        Type HELP LOADER or HELP MODBUILD for more info.

More info.
==========
See 12ODES.HLP, PQRDOT.HLP, EULERDOT.HLP, and XYHDOT.HLP for more
info about the determination of the other state variables. See
XDOTCORR.HLP for more details about the correction to beta-dot,
which needs to be made afterwards to the output from VABDOT.

VABDOT uses outputs from FMDIMS and HLPFCN as inputvectors; see
FMDIMS.HLP and HLPFCN.HLP for more details.

The helpfiles UVW.HLP and UVWDOT.HLP give some information about
the body-axes velocities and their time-derivatives, which are
closely related to (time-derivatives of) V, alpha, and beta.

See also EQMOTION.HLP.

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The FDC toolbox, Copyright Marc Rauw 1994-1998.