The calculations for the Auto Pilot are based on "System Dynamics". System Dynamics is used for Business simulation as well as combinations of physical and economical simulations. There are some tools for making simulation models like this, and the best of them (Powersim Studio) is used to develop and test the Auto Pilot used in GPS Map Explorer. Powersim Studio is by most people considered as the best tool, because it is implementing the unit of the variables in their value, and that is also perfect for a case like this. There are two relevant feedback loops in the Auto Pilot model; one to prevent the boat to change heading, and one to turn the heading towards the desired heading.
Below you see the cockpit of the simulation model:
To play with the simulation model, you need to install Powersim Studio. You can download a free time limited evaluation copy from www.powersim.com, and then run the simulation file that you may download here.
Below you see a simplified version of the model structure:
As you may see, the problem of not having any analogue rudder sensor is the big delay we get in the information of the heading and the change of heading for the boat.
You can use the simulation model to learn how to tune the Auto Pilot in the best way.
Downloads: GPS Map Explorer (2.4 MB) (This is the only file you need to use the Auto Pilot. See also the main information page about the software)
Because of the lack of feedback information from the rudder, this Auto Pilot can't calibrate itself, like many other Auto Pilots do. Therefore you must tune the parameters yourself. This is easy, both in the simulator and in the boat, by first using the test mode to tune sensitivity, then go to normal mode and tune the sharpness.
