• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.70-77
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• 2005

The study was results obtained from the trial make of the hybrid GPS-electromagnetic(EM) compass which overcome shortcoming of GPS compass and EM compass. The results were summarized as follows: GPS compass detected the stable ship's heading at 0.1^{\circ}$ intervals with the turning angular velocity of less than 25^{\circ}$/sec in the experiment for the characteristics of turning angular velocity with stepmotor, but in case of over 25^{\circ}$/sec the compass did not detect it. On the contrary, the EM compass always indicated the ship's heading with no connection of the turning angular velocity, however the compass is low accuracy compared with GPS one owing to a compass error. The ship's headings by the hybrid GPS-EM compass were displayed at fixed point and moving by car; if the GPS compass work the headings were displayed by GPS compass, if not, the heading is provided stably by adding or subtracting of a compass error to the heading of EM compass. Also, each ship's heading was derived from not only the GPS compass but also the EM one by add or subtract of the compass errors, and then was worked covariance for the analogy. The results show that the ship's heading of two compasses has been verified the similarity to 95% confidence level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.865-871
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• 2011

Presently, the location and direction information are certainly needed for the autonomous vehicle of the ship. Among them, the direction information is a essential elements to automatic steering system. And the gyro-compass, the magnetic-compass and the GPS compass are the sensor indicating the direction. The gyro-compasses are mainly used in the large-sized ship of the GMDSS(Global Maritime Distress & Safety System). The precision and the reliability of the gyro-compasses are excellent but big volume and high price are disadvantage. The magnetic-compass has relatively fine precision and inexpensive price. However, the disadvantage is in the influence by the magnetism object including the steel structure of a ship, and etc. In the case of the GPS compass, the true north is indicated according to the change of the location information but in case of the minimum number of satellites or stopping of a ship or exercise in the error range, the exact direction cannot be obtained. In this paper, the performance of the GPS compass was improved by using the least-square curve fitting method for the mutual trade off of the angle sensor. The algorithm which improves the precision of an azimuth by applying the weighted value according to the size of covariance error was proposed with GPS-compass and magnetic compass. The characteristic and the performance of the proposed algorithm were analyzed and verified through experimentation. The applicability of the proposed algorithm was shown through the experimental result.

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.67-68
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• 2004

• The Journal of Engineering Research
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• v.7 no.1
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• pp.61-70
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• 2005

Conventional geological survey utilizes the manual compass for mass amount of measurements of the geologic structure. Portable multifunction digital compass system was required by more detailed geological survey, due to increasing construction for rock slopes and runnels. In this paper, the system was implemented by using Intel PXA 255 embedded board as a system controller, and was composed of tilting sensor, digital azimuth sensor, and Global Positioning System (GPS) module. After the measured location, strike, and the angle of dip with our implemented system were transmitted to Personal Digital Assistant (PDA) or notebook, these data could be used for geologic structure analysis. It is expected that the availability of cheap and improved digital compass will reduce the coast and time of geological survey extensively.

• Journal of Navigation and Port Research
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• v.41 no.4
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• pp.189-194
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• 2017

The Moving Search Radar System (MSRS) monitors sea areas by moving along the coast. Since the radar is initially aligned to the front of the vehicle, it is important to know the changes in the heading azimuth of the vehicle to quickly acquire the target azimuth from the radar after the MSRS has moved. The heading azimuth can be obtained using the gyro compass, the GPS compass or the electronic compass. The electronic compass is suitable for MSRS requiring fast maneuverability due to its small volume, short stabilization time and low price. However, using a geomagnetic sensor may result in an error due to the surrounding magnetic field. Errors can make early automatic tracking of the satellites difficult and can reduce the radar detection accuracy. Therefore, this paper proposes a method to automatically compensate for the error reflecting the correction value on the radar obtained by comparing the reference azimuth calculated by solving the geodesic inverse problem using two coordinates between the radar and the geostationary satellite with the actually-directed azimuth angle of the satellite antenna. The feasibility and convenience of the proposed method were verified by applying it to the MSRS in the field.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.1
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• pp.50-55
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• 2010

The ship's heading information of hybrid GPS/EM compass were applied to the AIS of fishing vessel and examined the possibility of accuracy improvement. It is observed 453 each in AIS receiver of land among 3,982 each in AIS Rx/Tx transponder of the test ship at sea, and transmission interval according to the speed of ship is determined the 11.4% good transmitting data of the all information. In results, maximum compass error for the ship's heading of an EM compass was $19.1^{\circ}$. The variance of ship's heading owing to the speed of ship is surveyed. The COG (Course Over Ground) was changed extremely in $180^{\circ}W-179^{\circ}E$ range under 4.9knots, and in $24^{\circ}W-23^{\circ}E$ range over 4.9knots. Finally, using the ship's heading of EM compass and the COG from GPS for the autopilot system of a small fishing boat and the ship's heading information of AIS results in danger on the own ship's navigation safety and leads to make confusion both the others and VTS (Vessel Traffic Service) center. Therefore, the hybrid GPS/EM compass is identified as the best system for a small fishing boat and is allowed to offer continuously a ship's heading information with high accuracy and stability.

• Journal of Biosystems Engineering
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• v.23 no.2
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• pp.179-186
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• 1998

This study was conducted to sense posture of an autonomous tractor using a DGPS, a gyro compass, and a potentiometer. Posture sensing system was constructed and its accuracy was evaluated. The accuracy of DGPS was evaluated under stationary and moving conditions, and the performance of the gyro compass and the potentiometer was investigated by measuring bearing and steering angles, respectively. Also, the effect of DGPS interference by obstacles was evaluated experimentally. The position accuracy was about 6.6cm(95%) under the stationary condition and 10 cm at sharp turning condition. Steering angle of the tractor could be related linearly to the output of the potentiometer that was installed on the rotating center of a knuckle arm. The positioning accuracy of the DGPS varied significantly according to the number of visible GPS satellites, but was good with more than 7 satellites. The DGPS gave bad solutions for sensing the posture of tractor when signals from satellites or the correction data from the base were interfered by obstacles.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.118-124
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• 2008

Recently fishing industry is interested in efficiency and automation to acquire the international competitive power of national fishing industry. As an automation device of fishing boat, there are electric compasses using GPS and terrestrial magnetic sensor. Electric compass can be minimum size, high effectiveness with keeping the characteristic of a magnetic compass. This can be used a heading angle sensor to construct auto-navigation system in a small size ship. This paper develop electronic compass system that has serial output signal in NMEA 0183 and demonstrates the possibility of the electronics compass in navigation system for a small sized ship.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.381-382
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• 2007

Recently fishing industry is interested in efficient and automated fishing implementations to reach the level of the international leading technology. One of the important device used in fishing boat is an automated electric compass that harnesses the GPS and terrestrial magnetic sensor. The electric compass is desired to be minimized in size while keeping a high effectiveness in the characteristic of a magnetic compass. This device also can be used as a heading angle sensor to construct auto-navigation system in a small size of ships. However, there exists measurement errors induced from the slope of terrestrial magnetic sensor caused by the motion of boat. In this paper, a method has been proposed removing the measurement error arising from the slope of terrestrial magnetic sensor when the ship is in motion. We have designed a sensor with two DOF(degree of freedom) and a weight to maintain the horizontality of the sensor. Through this research, the hardware has been designed and also a test has been performed. The test shows a promissory result.