How Potentiometers are Used in Marine Steering Systems
A Potentiometer “Pot” is a variable resistor that is used to produce an analog (Variable) signal to a processor or control mechanism. It can be used as a command device or a feedback device.
In this explanation, we will use a ship’s electro-hydraulic steering system as an example.
In the wheelhouse, there is either a lever or a wheel that houses a Potentiometer. This is what we will refer to as Command signal. In the ship’s steering compartment where the mechanical steering system is located, we have a device that detects the rudder’s exact position in degree angle at any given time. This is called the Rudder Feedback Unit (or Rudder Reference Unit) we will refer to this as the Feedback signal.
The electronic processor that is designed to control the steering system uses the Command signal as the Rudder Order (the rudder position that is desired)
Both the command POT and Feedback POT utilize a fixed Voltage across the + and – terminals and output a variable voltage as the signal value.
The captain moves the lever or wheel and the command POT sends a specific voltage value to the processor indicating the desired rudder angle. The processor then converts that command into a value to drive the steering rudder to the requested position, for example, 10 Degrees to Starboard (Right Side of the ship) The feedback POT then tells the processor what position the rudder is currently in with the same type of voltage value that the command uses. The processor then determines which direction to move the rudder in, starts moving the rudder until it reached the desired position in this case 10 degrees to Starboard.