Compass Deviation Research Articles

Bionic Magnetic Compass Algorithm Based on Radical Pair Theory

Vector magnetometers play an essential role in aerial and marine navigation due to their advantages of low cost, portability, and high sensitivity. However, the unstable magnetic field anomaly restricts the performance improvement of the magnetic compass. The existing methods have done a lot of optimization and improvement work, but the test results are less than expected in a dynamic environment. In order to solve this problem, a bionic magnetic compass algorithm based on the theory of “radical pairs” in birds was proposed. This article finds the stability convergence of the magnetic compass deviation (MCD) at the critical angle. The theoretical analysis and experiment results show that the heading accuracy at the critical angle is trustworthy. Then, the MCD distribution and the magnetic heading correction model are established. Finally, the current magnetic heading is corrected according to the angle difference between the critical angle and the current heading. The sea trial shows that compared with the traditional compensation algorithm, the reservoir environment is improved by 83.1%, and the effect in real ocean environment is improved by 30.12% and 58.49%.

Calculation of the deviation coefficients for marine magnetic compass

ABSTRACTDeviation coefficients of magnetic compass are a basis to determine the compass deviation as well as to establish the table for compass deviation which is considered as technical certificate for magnetic compass equipped on board the ship. Normally, magnetic compass correction expert needs to observe the deviation values in main course of compass and then insert them into deviation equation system for obtaining the deviation coefficients. In the existing method, the special courses for requirement are on eight main directions such as (N, S, E, W, NE, SE, SW, and NW). These special courses and respective deviations are replaced into the deviation equation to obtain eight equations. Then, by expanding the equations, the deviation coefficients are found out. However, this method has some drawbacks: The observed courses are special ones; the solution of equation is impossible if the number of observation is less than eight. In this paper, the author suggests a new method to calculate the deviation coefficients of compass quickly by observing the compass’s deviation in any course. This method is easy to carry out and without requirement of deviation observation on special courses.

Towards an Improvement of Magnetic Compass Accuracy and Adjustment

Many ship accidents have arisen from an error in course indication. Bearing in mind that the actual errors in gyrocompass and satellite compass are really minor, they may be considered valid to be input into an autopilot provided that any failure in such devices is controlled by means of a secondary heading source such as a magnetic compass. However, magnetic compass deviation may be significant and its heading should be corrected before being input to the autopilot. The errors caused by the geographic variability of the deviation should also be taken into account. Moreover, the current way to reduce the deviation requires that the ship is un-berthed to execute a complete swing. The aim of this article is to obtain a ship magnetic model by means of an algorithm based on least squares to correct magnetic compass heading input in the autopilot and to permit definitive magnetic compass compensation without swinging the ship through 360°.

Correction of ADCP Compass Errors Resulting from Iron in the Instrument’s Vicinity*

AbstractIron in the vicinity of compasses results in compass deviations. ADCPs mounted on steel buoyancy devices and deployed on seven moorings on the East Greenland outer shelf and upper slope from 2007 to 2008 suffered from severe compass deviations as large as 90°, rendering the ADCP data useless without a compass correction. The effects on the measured velocities, which may also be present in other oceanic velocity measurements, are explained. On each of the moorings, velocity measurements from a different instrument are overlapping in space and time with the compromised measurements. The iron was not in the vicinity of this second instrument, and the instrument is therefore assumed not to be affected by compass deviations. A method is described to determine the compass deviation from the compromised and uncompromised velocity measurements, and the compromised compass headings. The method depends on the assumptions that at least one instrument per mooring is not compromised and that the change in flow direction over the vertical distance from the compromised to the uncompromised velocity measurement is zero on average. With this method, the compromised headings and the compromised velocity records can be corrected. The method is described in detail and a MATLAB function implementing the method is supplied. The success of the method is demonstrated for a mooring with a minor compass deviation and for one with a large amplitude deviation.

Taming Poseidon’s Beast of Uncertainty: The Auspicious Debut of Marine Engineer Aleksej Nikolaevich Krylov (1863–1945)

This paper reviews the career of the late nineteenth- and early twentieth-century Russian engineer Aleksej Nikolaevich Krylov (1863–1945). He made prodigious contributions to the fields of marine engineering, naval architecture, strength of materials, physics, analogue computers, ballistics, applied mathematics, astronomy, and engineering education. Surprisingly unknown in the West today, Krylov had achieved international fame in 1899 when he became the first foreigner to receive a gold medal from the Royal Institution of Naval Architects in London. After the years of upheaval following the Russian Revolution of 1917 and the subsequent civil war, Krylov was instrumental in re-establishing scientific contacts with the West and defining Soviet technological policy. Later in life, his erudition extended into the history of science and technology. This paper focuses on his first ground-breaking work: the development of methods to correct compass deviation and the corresponding design of his new dromoscope.

Latitude Error in Compass Deviation: Mathematical Method to Determine the Latitude Error in Magnetic Compass Deviation

Abstract This article aims to provide the seafarer with a tool to calculate the deviation for a righted ship in any geographical position using only the information available on board. In this way the accidental errors in the deviation card are reduced and the latitude error is made negligible. Moreover, an experimental application of this method is carried out on board a tanker to compare the latitude error in different positions at sea.

数字磁罗盘的全姿态罗差补偿

To overcome the shortcomings of the existing magnetic deviation compensation methods in high costs,low efficiency and insufficient tilting compensation ability,a new method based on geometric transformation was proposed to compensate the attitude magnetic deviation of the digital magnetic compass.Firstly,the effect of the magnetic interference on the output of a magnetic sensor was analyzed and a geometric transformation model for the compass deviation was established to reduce the number of magnetic deviation parameters from 12 to 9.Then,a hybrid algorithm for solving these 9 parameters was proposed,in which the Particle Swarm Optimization(PSO) algorithm was taken to adjust the initial value and the Newton algorithm was used to accelerate the convergence process.Finally,the compensation method was used to compensate the magnetic heading error.The experimental results show that the method can achieve the all attitude magnetic deviation compensation without other assisting magnetic heading information,the compensation time is less than 3 min and the magnetic heading error is 1/8～1/10 that before compensation.The method is prior to traditional method in the speed and accuracy and satisfies the requirement of the system for attitude and heading reference.

Application of the Least Squares Method for Determining Magnetic Compass Deviation

This paper describes an algorithm for evaluation of magnetic compass deviation based on the least squares method. An automatic system was built, coupled with a magnetic compass recording device, for fine estimation of the deviation curve on the basis of an incomplete compass swing circulation.

Compass Deviation Analysis and Compensation for a Three-axis Strapdown Magnetic Heading System

This paper presents the development of a high accuracy three-axis strapdown magnetic heading measurement system for vehicle navigation guidance and control. Analysis is made on compass deviation, the main error for the system. The analysis considers the effects of vehicle tilt, permanent magnetic field, and soft iron magnetism, A compass deviation equation is obtained, which can be used in conjunction with a microcomputer to compensate for the error at arbitrary vehicle attitude, The system is capable of compensating error under different environment conditions and is, in fact, an intelligent sensor. Experimental result is presented to demonstrate the effectiveness of the system.

3軸固定型電子コンパスの磁気緯度に対する自差補正

3軸固定型電子コンパスの磁気緯度に対する自差補正

Magnetic properties of nonmagnetic drill collars and their relation to survey compass error

A full investigation of nonmagnetic drill collars was undertaken to check whether these collars induce significant errors in magnetic directional survey instruments which are positioned within the collar during measurement. Laboratory determinations of magnetic permeability and saturation remanence were made on samples taken from the collars, and field inspections were carried out on new and used nonmagnetic drill collars. Twenty per cent of all the nonmagnetic collars examined were found to be magnetised by differing amounts. Theoretical estimates of magnetic compass deviation due to 1. (a) the permeability of the nonmagnetic drill collar, and 2. (b) the permanent magnetisation of a section of the collar, are included in separate appendices.

ブロツク式建造漁船における船内磁場の分析(日本航海学会第33回講演会)

The magnetized state of the ship's body by block system differs from that by the system heretofore in use (riveted structure), despite of the magnetic compass deviation depending on it. This report dealt with the magnetism of the ship's body of "Tenyo-maru" built by block system in relation to her structure or to the direction of her head during construction. And the results obtained are summarized as follows : (1) The magnetic force of the ship's body was weaker on the compass bridge deck than on other deck. (2) The components of the magnetic field of the ship's body could be arranged as follows according to the intensity : vertical field, horizontal permanent field, induced field by athwartships horizontal soft iron, and that by fore-and-aft one. (3) The ship's body was more strongly magnetized on building berth than on fitting-out basin, but the direction of permanent magnetic field of the ship's body did not always depend on the building direction. (4) There was great magnetic force at the stations near the transceiver of marine radar. And the effect of local magnetic field due to nearby transceiver of radar, in some case, could not be compensated for by the ordinary correctors. (5) Vertical magnetic field by the ship's structure was directed downwards on the compass bridge deck and upwards on the navigation bridge deck.

緯度変化に伴う自差の変動について : フリンダースバーの修正用図表(日本航海学会第28回講演会)

緯度変化に伴う自差の変動について : フリンダースバーの修正用図表(日本航海学会第28回講演会)

ブロツク式船体建造による磁気羅針儀の乱調(日本航海学会第18回講演会)

ブロツク式船体建造による磁気羅針儀の乱調(日本航海学会第18回講演会)

Magnetic Compass Deviation and Correction: A Manual of the Theory of the Deviation and Mechanical Correction of Magnetic Compasses in Ships. W. Denne (1951), 149, xx, 67 figures, cloth, 8·8 × 5·8 in., Brown, Son & Ferguson, 21s.

Magnetic Compass Deviation and Correction: A Manual of the Theory of the Deviation and Mechanical Correction of Magnetic Compasses in Ships. W. Denne (1951), 149, xx, 67 figures, cloth, 8·8 × 5·8 in., Brown, Son &amp; Ferguson, 21<i>s.</i>

偏針儀による自差修正についての一考察

偏針儀による自差修正についての一考察

Correcting Compass Deviation

Correcting Compass Deviation

Correcting Compass Deviation

Correcting Compass Deviation

A New form of Battery-Cell

A New form of Battery-Cell