After further research I've edited this post as it was incorrect.
I am using the Arduino Uno. If you have been able to use the code provided without having to declare PD4, PD7, PB0, PB1 please let me *
Even though these ports are defined in some of the header files they don't seem to be defined for the Uno i.e. when selecting "Arduino Uno" from Tools->Board in Arduino IDE.
If instead I select "Arduino Diecimila or Duemilanouve w/ ATmega168" or "Arduino Nano w/ Atmega168" then it compiles fine.
Otherwise I get the following errors;
XPID.ino: In function 'void setup()':
XPID:280: error: 'PD4' was not declared in this scope
XPID:281: error: 'PD7' was not declared in this scope
XPID:282: error: 'PB0' was not declared in this scope
XPID:283: error: 'PB1' was not declared in this scope
These errors are correct as mentioned in the above by adding these 4 lines;
int PD4 = 4;
int PD7 = 7;
int PB0 = 8;
int PB1 = 9;
Of course if I select a board that already has these variables defined I don't need the above. In fact I would get a different error which must be a result of the variables already being defined in the header file.
XPID:183: error: expected unqualified-id before numeric constant
Arduino setup with position 2 actuator off center with PWM and ControlInput led on

ArduinoUno.JPG (45.73 KiB) Viewed 6008 times
- ArduinoUno Setup
X-Sim converter showing actuator off center by 13%

xsimconverter.JPG (26.46 KiB) Viewed 6008 times
- X-Sim Converter