ADDED   mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_abg.fig
Index: mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_abg.fig
==================================================================
--- mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_abg.fig
+++ mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_abg.fig
@@ -0,0 +1,29 @@
+#FIG 3.2
+Portrait
+Center
+Metric
+A4      
+100.00
+Single
+-2
+1200 2
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 3
+	 1575 3375 2925 3375 2700 3600
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 3
+	 3375 3375 4725 3375 4500 3600
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 3
+	 4950 3150 4950 1800 5175 2025
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 3
+	 5175 3375 6525 3375 6300 3600
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 3
+	 3150 3150 3150 1800 3375 2025
+2 1 0 2 0 7 100 0 -1 0.000 0 0 -1 0 0 2
+	 6525 3150 6525 3600
+2 4 0 2 31 7 51 0 -1 0.000 0 0 7 0 0 5
+	 7875 4275 7875 900 450 900 450 4275 7875 4275
+4 1 0 100 0 18 18 0.0000 4 195 150 3150 3465 0\001
+4 1 0 100 0 18 18 0.0000 4 195 150 4950 3465 1\001
+4 2 4 100 0 18 18 0.0000 4 270 870 1530 3465 SS:[in]\001
+4 0 4 100 0 18 18 0.0000 4 270 1065 6660 3465 SS:[out]\001
+4 1 0 100 0 18 18 0.0000 4 270 780 3150 1665 C:k_p\001
+4 1 0 100 0 18 18 0.0000 4 270 765 4950 1665 R:k_d\001

ADDED   mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_desc.tex
Index: mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_desc.tex
==================================================================
--- mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_desc.tex
+++ mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_desc.tex
@@ -0,0 +1,56 @@
+% -*-latex-*- Put EMACS into LaTeX-mode
+% Verbal description for system PDe (PDe_desc.tex)
+% Generated by MTT on Tue May 1 09:26:33 BST 2001.
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% $Id$
+% %% $Log$
+% %% Revision 1.1  2000/12/28 09:13:38  peterg
+% %% Initial revision
+% %%
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+   The acausal bond graph of system \textbf{PDe} is
+   displayed in Figure \Ref{fig:PDe_abg.ps} and its label
+   file is listed in Section \Ref{sec:PDe_lbl}.
+   The subsystems are listed in Section \Ref{sec:PDe_sub}.
+
+   This is a proportional + derivative (PD) controller for a
+   collocated sutuation where the control signal is an effort and the
+   measured signal is a (collocated) flow.
+
+   The controller can be thought of as controlling \emph{integated
+   flow}, and it is with respect to this that the P and D terms are defined.
+
+ The setpoint is a \emph{flow}; and must be generated to give the
+ desired \emph{integrated} flow.
+
+ Physically, the controller is a \textbf{C} and an \textbf{R}
+ component - for mechanical systems a mass and a spring.
+ 
+ Mathematically, in integral causality, the equations are:
+%file: pde_{dae}.tex
+%differential-algebraic equations
+ \begin{equation}
+   \begin{aligned}
+     \dot x_{1} &=
+     {
+       f_d - f
+       }
+   \end{aligned}
+ \end{equation}
+ \begin{equation}
+   \begin{aligned}
+     u &=
+     {
+       - k_{d} f + k_{p} x_{1}
+       }
+   \end{aligned}
+ \end{equation}
+
+ The state $x_1$ is the the integrated difference between 
+ \emph{desired} flow $f_d$ and the actual flow  $f$. Thus the control
+ signal $u$ is $k_p$ multiplied by the position error minus $k_d$ time
+ the flow.

ADDED   mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_lbl.txt
Index: mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_lbl.txt
==================================================================
--- mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_lbl.txt
+++ mttroot/mtt/lib/comp/compound/Control/Collocated/PDe/PDe_lbl.txt
@@ -0,0 +1,39 @@
+%% Label file for system PDe (PDe_lbl.txt)
+%SUMMARY PDe: Proportional + Derivative controller with effort output
+%DESCRIPTION 
+
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% Version control history
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% %% $Id$
+% %% $Log$
+% %% Revision 1.1  2000/12/28 09:13:38  peterg
+% %% Initial revision
+% %%
+% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+% Port aliases
+%ALIAS	in	in
+%ALIAS	out	out
+
+% Argument aliases
+%ALIAS	$1	k_p
+%ALIAS	$2	k_d
+
+%% Each line should be of one of the following forms:
+%	     a comment (ie starting with %)
+%	     component-name	cr_name	arg1,arg2,..argn
+%	     blank
+
+% ---- Component labels ----
+
+% Component type C
+	k_p	lin		state,k_p
+
+% Component type R
+	k_d	lin		flow,k_d
+
+% Component type SS
+	[in]	SS		internal,external
+	[out]	SS		external,external