Compass is a navigational instrument for determining direction in the form of an arrow pointing magnetic freely align itself with Earth's magnetic field accurately . Compass provide certain reference direction , so it is very helpful in the field of navigation . Designee cardinal directions are north , south , east , and west . When used together with clock and sextant , the compass will be more accurate in showing the direction . This tool helps the development of maritime trade by making travel safer and much more efficient than when humans still based on the position of the stars to determine direction .
The discovery that the magnetic needle always points to north and south occurred in China and described in the book Loven Heng . In the ninth century , the Chinese have developed a compass needle floating and rotating needles . Persian sailors obtain the compass from the Chinese and then trade . But only in 1877 the Englishman , William Thomson , 1st Baron Kelvin ( Lord Kelvin ) made a compass that can be accepted by all countries . By correcting errors arising from magnetic deviation due to the increased use of iron in ship architecture .
Any device that has a rod or a magnetic needle free to move pointed toward magnetic north of a planet's magnetosphere can already be considered as a compass . Compass watch is equipped with a compass sundial . Compass variation fragile structure is a special tool that is used by observing variations of the needle movement . Girokompas used to determine true north .
Location of the magnetic North Pole is always shifted from time to time . Recent research conducted by the Geological Survey of Canada reported that the position of the magnet is moving about 40 miles per year to the northwest .
The type of compass .
Compass can be divided into two types , namely the analog compass and a digital compass .
Analog compass .
Analogue compass is a compass that we see in everyday life . For example, the compass that is used when a scout event . While the digital compass is a compass that has used the digitization process . In other words the workings of the compass using computerized .Digital compass .
The creation of a digital compass aims to complement the needs of an increasingly sophisticated robotics . Robotics world is in dire need navigation tools effectively and efficiently . While the navigation system tools available in the market are expensive . While the compass itself is an effective tool navigation system at a cheaper price . therefore expected to substitute digital compass tool in robot navigation systems .Digital compasses on the market many kinds. Among these are artificial CMPS03 Devantech Ltd. Magnetic Compass . CMPS03 measuring 4 x 4 cm using Philips KMZ51 magnetic field sensor is sensitive enough to detect the Earth's magnetic field . The digital compass is quite supplai voltage of 5 Vdc with 15mA current consumption. In CMPS03, cardinal directions are divided in the form of degrees, namely : North ( 0 ) , East ( 90 ) , South ( 180 ) and West ( 270 ) .
There are two ways to get a share of the direction of the digital compass is by reading the PWM signal ( Pulse Width Modulation ) on pin 4 or the I2C interface to read the data on pins 2 and 3 . PWM signal is a signal that has been modulated pulse width . In CMPS03 , positive pulse width represents the angle of direction . Pulse width varies between 1mS ( 00 ) until 36.99mS ( 359.90 ) . In other words, the pulse width changes by 100uS each rank . The signal will be low for 65mS between pulses , so that the total period is 65mS + the positive pulse width (between 66mS to 102mS). The pulses generated by 16-bit timer in the processor, which provides a resolution 1uS .
In addition to PWM , CMPS03 also equipped with an I2C interface that can be used to read the data direction in the form of serial data . In 8 -bit mode , the direction north indicated by the data 255 with a resolution of 1.40625 degrees / bits . In 16 -bit mode , the direction north indicated by the data of 65535 so that the resolution be 0.0055 degrees / bits .
Of the various kinds of digital compass above it can be seen that the digital compass digital compass CMPS03 is the most good . Although the compass is nice because the picture can be displayed in the LCD screen character , but this compass can not be used by all types of robots . This is because every robot has a need for a navigation system in the form of a digital compass that different between the robots with other robots . It is possible types of robots A type B requires a digital compass , and there is the possibility that the compass can not be substituted by other compass .
Thank you for reading this article. Written and posted by Bambang Sunarno.
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http://www.primadonablog.blogspot.com/2014/03/did-you-know-about-compass.html
DatePublished : March 28, 2014 at 17.26
Tag : Compass.