aclin.m

MATLAB在飞行动力学和控制中应用的工具

      if exist('xinco') == 0 | exist('uaero0') == 0 | exist('uprop0') == 0
         disp(' ');
         disp('No operating point defined!');
         disp(' ');
         disp(' ');
         disp('<<< Press a key to return to main menu >>>');
         pause
      else
         ok = 1;
      end
   else                                                             % QUIT
                                                                    % ----
      ok   = 1;
      skip = 1;  % Return to end of program rightaway when quitting.

   end

end % of operating-point definition.
clear ok

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


if skip ~= 1   % If not quitting from ACLIN, proceed with program.
               % Else, go to end of program rightaway!

   disp(' ');
   disp('<<< Press a key to proceed with model definition >>>');
   pause

   % Define parameters for aircraft model:
   % =====================================
   %
   % AM, EM, GM1, and GM2: matrices, containing parameters for the aircraft
   %                       model. See also the help text and source code for
   %                       MODBUILD.M (contained in the directory AIRCRAFT).
   %
   % The other variables will either be explained when they are used, or are
   % self-explaining (at least if you know something about aircraft stabi-
   % lity and control).
   %
   % Check if these variables already have been defined in the Matlab work-
   % space (by ACTRIM). If not, run LOADER to retrieve them from file.
   % -----------------------------------------------------------------------
   if exist('AM')==0 | exist('EM')==0 | exist('GM1')==0 | exist('GM2')==0
      loader
   end

   % The systems BEAVER and BEAVER1 use a gain block for arbitrarily setting
   % time-derivatives of the state variables to zero. This may be useful for
   % some purposes, for instance to eliminate longitudinal-lateral cross-
   % coupling, or to fix the airspeed to its initial value if an altitude
   % controller is to be evaluated, but no autothrottle is available yet.
   % The gain value is xfix, which is set to 1 if all states may vary, i.e.,
   % if the complete six degree-of-freedom model is used without restric-
   % tions. When states have to be fixed, the routine FIXSTATE.M can be
   % called (type HELP FIXSTATE for more info).
   %
   % Here, all state variables are allowed to vary, so xfix will be set to
   % one. Replace this line by:
   %
   %   fixstate;
   %
   % if you want to set some time-derivatives to zero, even when linearizing
   % the aircraft model.
   %-------------------------------------------------------------------------

   xfix = 1;
   %%%% fixstate;

   disp(' ');
   disp('<<< Press a key to proceed with linearization >>>');
   pause


   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


   % Proceed with linearization.
   % ===========================

   % Build initial inputvector to the system (contains both aerodynamic
   % and engine inputs). Note: wind velocities and accelerations (inclu-
   % ding atmospheric turbulence) have been set to zero!!!
   % -------------------------------------------------------------------
   uinco = [uaero0; uprop0; 0; 0; 0; 0; 0; 0];

   clc
   disp(['Now linearizing S-function ',sysname]);
   disp(' ');
   disp('Wait a moment, please...');
   home

   % Apply Simulink routine LINMOD to nonlinear aircraft model, contained
   % in the S-function sysname. Note: contrary to the routine ACTRIM, the
   % linearization tool LINMOD is a standard Simulink function. Hence, it
   % is not necessary to initialize the system at this place by calling
   % it once with [sys,x0] = sysname([],[],[],0)!
   % --------------------------------------------------------------------
   [Aac, Bac, Cac, Dac] = linmod(sysname,xinco,uinco);

   disp(' ');
   disp('Linearization succeeded.');
   disp(' ');
   disp('<<< Press a key to continue >>>');
   pause


   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


   % Select a subset of the states and inputs. Note: the remaining states
   % and inputs are omitted from the state equation by simply eliminating
   % the corresponding elements from the state matrices. The more elements
   % you neglect, the larger the resulting error will be.
   %
   % ACLIN doesn't provide the option to choose a subset of the output
   % equations, because the exact definition of the outputvector from the
   % Simulink system which contains the nonlinear aircraft model is not
   % known (in general). The full twelfth-order linear aircraft model
   % does include the output equations y = Cac*x + Dac*u, but the exact
   % definition of the matrices Cac and Dac, and the outputvector y can be
   % determined only by checking the corresponding nonlinear Simulink
   % model!
   % =====================================================================

   % While-loop in which the user must specify the element numbers of the
   % STATES that should be used for the linear model. These element num-
   % bers are stored in the vector xdef (state definition).
   %
   % The flag 'allstates' is set to one if user wants to maintain defini-
   % tion of state vector. If not, allstates = 0.
   % --------------------------------------------------------------------
   allstates = 0;
   ok = 0;
   while ok ~= 1
      clc
      disp('Select states');
      disp('-------------');
      disp(' ');
      disp('The current state vector is: ');
      disp(' ');
      disp('x = [ V  alpha  beta  p   q   r  psi  theta  phi  xe  ye  H ]''');
      disp(' ');
      disp('      1    2      3   4   5   6   7     8     9   10  11  12');
      disp(' ');
      disp(' ');

      disp('Enter vector with element numbers of states you want to use');
      disp('(enter = use all states):');
      xdef = input('> ');
      if isempty(xdef)                    % Use all states.
         xdef = [1 2 3 4 5 6 7 8 9 10 11 12];
         allstates = 1;                   % Set all states flag.
      end

      % Check if no illegal numbers have been specified.
      % ------------------------------------------------
      if min(xdef) < 1 | max(xdef) > 12   % state numbers outside allowable
                                          % region...
         disp(' ');
         disp('Use element numbers from {1,2,3,4,5,6,7,8,9,10,11,12}!');
         disp(' ');
         disp('<<< Press a key >>>');
         pause
         ok = 0;
      else
         ok = 1;
      end
   end

   % While-loop in which the user must specify the element numbers of the
   % INPUTS that should be used for the linear model. These element num-
   % bers are stored in the vector udef (input definition). Note: wind
   % and turbulence inputs (disturbances) are selected separately.
   %
   % The flag 'allinputs' is set to one if the user wants to maintain
   % the full inputvector, INCLUDING atmospheric disturbances. If not,
   % allinputs = 0.
   % --------------------------------------------------------------------
   allinputs = 0;
   ok = 0;
   while ok ~= 1
      clc
      disp('Select inputs');
      disp('-------------');
      disp(' ')
      disp('The current control-input vector is: ');
      disp(' ');
      disp('u = [ deltae deltaa deltar deltaf   n   pz ]''');
      disp(' ');
      disp('          1      2      3     4     5    6');
      disp(' ');
      disp(' ');

      disp('Enter vector with element numbers of control inputs that you want');
      disp('to use (enter = use all control inputs):');
      udef = input('> ');
      if isempty(udef)                    % use all control inputs.
         udef = [1 2 3 4 5 6];
         allinputs = 1;                   % set all inputs flag (will be
                                          % reset to 0 if influence of wind
                                          % & turbulence is neglected later).
      end

      % Check if no illegal numbers have been specified.
      % ------------------------------------------------
      if min(udef) < 1 | max(udef) > 6    % input numbers outside allowable
                                          % region...
         disp(' ');
         disp('Use element numbers from {1,2,3,4,5,6}!');
         disp(' ');
         disp('<<< Press a key >>>');
         pause
         ok = 0;
      else
         ok = 1;
      end
   end

   clear ok

   % Include wind and turbulence inputs (disturbances) to inputvector?
   % -----------------------------------------------------------------
   disp(' ');
   answ = input('Include wind & turbulence inputs (y/n)? ','s');
   if answ == 'y'
      udef = [udef 7 8 9 10 11 12];
   else
      allinputs = 0;  % Reset all inputs flag. Wind and turbulence are
                      % neglected, so user does NOT want to consider
                      % full inputvector!
   end
   clear answ

   % If user has selected all states AND all outputs, including the
   % atmospheric disturbances (wind & turbulence), there is no need
   % to determine new, simplified matrices for the linearized model,
   % because Aac_s == Aac and Bac_s == Bac in that case. If the user
   % has selected a subset of x and u, or if he has defined the vectors
   % xdef and udef such that the order of the states and/or inputs is
   % shuffled, simplified versions of Aac and Bac will be created.
   %
   % First check if user has specified full state and inputvector
   % (unshuffled) for linearized model. If not, define Aac_s and Bac_s.
   % ------------------------------------------------------------------
   if allstates ~= 1 | allinputs ~= 1

      % Determine new state matrix Aac_s, depending upon element numbers
      % selected above.
      % ----------------------------------------------------------------
      for ii = 1:length(xdef)             % ii = row number
         for jj = 1:length(xdef)          % jj = column number
            Aac_s(ii,jj) = Aac(xdef(ii),xdef(jj));
         end
      end

      % Determine new state matrix Bac_s, depending upon element numbers
      % selected above.
      % ----------------------------------------------------------------
      for ii = 1:length(xdef)             % ii = row number
         for jj = 1:length(udef)          % jj = column number
            Bac_s(ii,jj) = Bac(xdef(ii),udef(jj));
         end
      end

      clear ii jj

   end

   clc;
   disp('State-space matrices of complete 12th-order system:');
   disp('Aac, Bac, Cac, and Dac.');
   disp(' ');
   if allstates ~= 1 & allinputs ~= 1
      disp('State-space matrices of simplified model (state equation only):');
      disp('Aac_s and Bac_s');