ComNav 1101 - System Overview; Core System Components

ComNav 1101 Autopilot
3. System Overview
At the core of the Autopilot System is a microprocessor-based PID
(Propor tional-Integral-Differential) controller. This controller works
from either a high quality, externally gimbaled magnetic ships
steering compass fitted with a Magnetic Compass Sensor, or a
direct earths field sensing Fluxgate Compass.
Heading information is compared against the commanded heading;
from this information, the desired rudder position is calculated. The
desired rudder position is then compared against the actual rudder
position transmitted by the Rudder Follower. If they are not the
same, either the port or starboard output line is activated.
Both the port and starboard output lines are active low (i.e. they
switch to ground). Each is capable of driving up to a 3-amp load.
These output lines are designed to drive solenoid valves in a
hydraulic steering system.
A speed control signal is also available for use with variable speed
rudder drives. All of the outputs, either by themselves or with an
optional solid state relay box, can be adapted to operate a wide
variety of power steering systems. If the Autopilot is installed as a
retrofit, it is usually possible to use the existing steering installa-
tion.
The system is designed to operate on a wide variety of vessels
operating with power systems of either 12 or 24 VDC.
The 1101 Autopilot is equipped to interface with a GPS, Loran C, or
any other navigation device that outputs one of the NMEA 0183
formats at 4800 Baud.
The 1101 Control Head functions as the main inter face between the
Autopilot System and the user. It contains a number of buttons and
an ADJUSTMENT knob through which the operator controls the
functions of the Autopilot. A large Liquid Crystal Display (LCD)
screen provides visual feedback of the operators commands and
shows the status of the Autopilot System at any given time while the
unit is powered up.
SYSTEM OVERVIEW 3 - 1