What Is The Error Of The Gyrocompass?

Latitude error or damping error

Cause: Caused by the vertical damping method.

The size of the error is related to the structural parameters of the compass and increases with the increase of latitude. North latitude to east error, south latitude to west error.

Elimination method

(1) External compensation method-calculate the size and sign of the latitude error according to the latitude error formula, and deduct it from the reading of the gyro compass;

(2) Internal compensation method-Calculate and output the signal transformed according to the latitude error law, and apply compensation torque to the gyro compass.

Speed error

Speed error refers to the deviation Angle of azimuth between the stable position of the main axis of the compass and the stable position of the main axis of the compass on the stationary base when the ship is sailing at constant speed.

Characteristic

1. Any compass will produce speed errors, which only depend on the speed, course and geographical latitude and have nothing to do with the structural parameters of the compass.
2. Increases with the increase of ship speed and latitude

Causes: The movement of the base changes the gyrocompass main shaft's involvement movement and produces pointing errors.

Elimination method

(1) Speed error correction table;

(2) External compensation method-use mechanical simulation method to calculate the error value according to the expression of speed error and deduct it from the heading reading;

(3) Internal compensation method—Calculate and output a regular speed error compensation torque to compensate the gyro compass.

Other errors

Impact error

When the ship is maneuvering, under the action of inertial force, the gyro compass spindle will change from the stable position at the beginning of maneuvering to the stable position at the end of maneuvering.
The impact error of the compass is called the first type of impact error because of the inertia moment generated by the inertial force acting on the control equipment.
The impact error of the compass is called the second type of impact error because of the inertia moment generated by the inertial force acting on the damping device.

When the ship is maneuvering, under the action of inertial force, the gyro compass main axis will change from the stable position at the beginning of the maneuver to the stable position at the end of the maneuver during the maneuver duration.

Baseline error

When the compass is installed or in use, the error occurs when the baseline of the compass is not coincident with or parallel to the bow and stern.It includes several line errors of main compass, base line errors of dividing compass and transmission errors.

Baseline: The reference line for reading the course of the main and subcompass.

Cause

When the compass is installed, there is no reading error caused by the baseline being parallel to the ship's fore and aft lines. When the compass is installed, the size and symbol of the baseline error do not change with the time, course and latitude and other factors, and is a fixed value.
If the baseline is on the port side of the bow, the compass course reading is less than the true course, and the baseline error is the east error; If the baseline is on the starboard side of the bow, the compass course reading is greater than the true course, and the baseline error is the west error; Both the main compass and the subcompass may have baseline errors, and the baseline error of the main compass will be reflected in the subcompass.
peculiarity
The size, symbol does not change with time, the course has nothing to do with the compass. Is a fixed value also known as a fixed error

Characteristic

The size, symbol does not change with time, the course has nothing to do with the compass. Is a fixed value also known as a fixed error.

Swing error

The error caused by the gyro compass when the ship is swaying.

Elimination method

(1) First eliminate the baseline error of the dividing compass
(2) After eliminating the baseline error of the main compass
Base line off port, compass position < true bearing, east error; Baseline to starboard, compass > true bearing, west error.

Error caused by the deviation of the main shaft from its stable position due to the inertial force caused by the ship's rocking acceleration applied to the control equipment of a single rotor compass.

Characteristic

It is related to the structural parameters of the compass, the installation position of the compass, the ship's swaying attitude, the geographical latitude and the ship's swaying direction parameters.
When sailing on a corner course and rolling, the swing error is the largest.

Elimination method

Underweight compass: using two rotors
Liquid connector compass: high viscosity silicone oil is used to increase the liquid flow cycle.
Electrically controlled compass: high viscous silicone oil is set in a strongly damped electromagnetic pendulum.
General elimination principle: Increase the swing period of the gyrosphere

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