File mttroot/mtt/lib/control/PPP/ppp_ex16.m artifact b34052bc15 part of check-in 33aa2293f3

function [name,T,y,u,ys,us,J] = ppp_ex16 (ReturnName)

  ## usage:   [name,T,y,u,ys,us,T1,du,dus] = ppp_ex16 (ReturnName)
  ##
  ## PPP example

  ## 	$Id$	


  ## Example name
  name = "Input constraints +-1.5 on u* at tau=0,0.1,0.2..,2.0 - intermittent control";

  if nargin>0
    return
  endif
  
  ## System
  A = [-3 -3  -1
       1  0  0
       0  1  0];
  B = [1 
       0 
       0];
  C = [0 -0.5  1];
  D = 0;
  [n_x,n_u,n_y] = abcddim(A,B,C,D);

  ## Controller
  t = [5:0.01:6];		# Time horizon
  A_w = 0;			# Setpoint
  A_u = ppp_aug(laguerre_matrix(3,2.0), A_w); # Input functions
  A_u = ppp_aug(laguerre_matrix(1,0.5), A_u); # Add some extra slow modes
  Q = ones(n_y,1);;

  ## Constaints
  Gamma = [];
  gamma = [];

  ## Constaints - u
  Tau_u = [0:0.1:2]; 
  one = ones(size(Tau_u));
  limit = 1.5;
  Min_u = -limit*one;
  Max_u =  limit*one;
  Order_u = 0*one;

  ## Constaints - y
  Tau_y = [];
  one = ones(size(Tau_y));
  limit = 1.5; 
  Min_y = -limit*one;
  Max_y =  limit*one;
  Order_y = 0*one;

  ## Simulation
  W=1;
  x_0 = zeros(3,1);

  ## Constrained - open-loop
  disp("Control design");
  [k_x,k_w,K_x,K_w,Us0,J_uu,J_ux,J_uw] = ppp_lin  (A,B,C,D,A_u,A_w,t,Q); # Unconstrained design
  [Gamma_u,gamma_u] = ppp_input_constraint (A_u,Tau_u,Min_u,Max_u);

  Gamma = Gamma_u;
  gamma = gamma_u;

  disp("Open-loop simulations");
  ## Constrained OL simulation
  [u,U] = ppp_qp (x_0,W,J_uu,J_ux,J_uw,Us0,Gamma,gamma);
  T = [0:t(2)-t(1):t(length(t))];
  [ys,us] = ppp_ystar (A,B,C,D,x_0,A_u,U,T);

  ## Unconstrained OL simulation
  [uu,Uu] = ppp_qp (x_0,W,J_uu,J_ux,J_uw,Us0,[],[]);
  [ysu,usu] = ppp_ystar (A,B,C,D,x_0,A_u,Uu,T);

  title("Constrained and unconstrained y* and u*");
  xlabel("t");
  grid;
  axis([0 6 -1 2]);
  plot(T,ys,T,ysu,T,us,T,usu)
  axis;

  ## Non-linear - closed-loop
  disp("Closed-loop simulation");
  Delta_ol = 0.1;
  [T,y,u,J] = ppp_qp_sim (A,B,C,D,A_u,A_w,t,Q, \
			  Tau_u,Min_u,Max_u,Order_u, \
			  Tau_y,Min_y,Max_y,Order_y,W,x_0,Delta_ol);

  title("y,y*,u and u*");
  xlabel("t");
  grid;
  plot(T,y,T,u,T,ys,T,us);
endfunction