Autonnic A5024 사용자 및 설치 설명서 - 페이지 10

{카테고리_이름} Autonnic A5024에 대한 사용자 및 설치 설명서을 온라인으로 검색하거나 PDF를 다운로드하세요. Autonnic A5024 19 페이지. Fluxgate compass

Calibration

4.1

Why the compass needs calibrating

When any compass is installed the magnetic characteristics of the whole

installation affect the way the Earth's field reaches the detector inside the

device. Each individual installation will be different and so the A5023 and

A5024 are equipped with an auto-calibration routine which corrects for

these installation distortions.

4.2

A NMEA-0183 command can be sent to initiate the process –

section 5.2.9

Switch 1 can be pressed.

There are two compass calibration techniques in common use:

Constant angular velocity

Double rotation without constant velocity.

The Autonnic compasses use the first method. The process consists of

rotating the whole installation in the Earth's field so that both permanent

magnets and induced magnets are corrected. The method used is the

single turn at a constant rate and this rate should be in range 60 to 180

seconds for the full 400 degrees needed. The whole arrangement is turned

at constant angular velocity because the method relies on applying a

correction when the heading measured is uneven with time.

The second method is not used by us. Autonnic has evaluated the method

which uses a mathematical model of an ideal compass and treats errors as

arising from distortion due to magnetic objects. The ideal error plot of the

field vector would be a circle with no offset from the origin. Permanent

magnets ('hard') have the effect of shifting the centre from the origin and

induced magnets ('soft') modify the circle into an ellipse. The results of

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A5023/24