• Journal of Institute of Control, Robotics and Systems
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• v.22 no.11
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• pp.967-976
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• 2016

This paper presents a 3D carrier-smoothed GNSS/DR (Global Navigation Satellite System/Dead Reckoning) integrated system for precise ground-vehicle trajectory estimation. For precise DR navigation on sloping roads, the AHRS (Attitude Heading Reference System) methodology is employed. By combining the integrated carrier phase of GNSS and DR sensor measurements, a vehicle trajectory with an accuracy of less than 20cm is obtained even when cycle slip or change of visibility occur. In order to supplement the weak GNSS environment with DR successfully, the DR sensor is precisely compensated for using GNSS Doppler measurements when GNSS visibility is good. By integrating a multi-GNSS receiver with low-cost IMU, a precise 3D navigation system for land vehicles is proposed in this paper. For real-time implementation, a decoupled Kalman filter is employed in the integrated system. Through field experiments, the performance of the proposed system is verified in various road environments, including sloping roads, good-visibility areas, high multi-path areas, and under-ground parking areas.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.100-106
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• 2013

This paper presents design and control of an 'Omni-directional Cleaning Robot (OdCR)' which employs omni-wheels at three edges of its triangular configuration. Those omni-wheels enable the OdCR to move in any directions so that lateral movement is possible. For OdCR to be localized, a StarGazer sensor is used to provide accurate position and heading angle based on landmarks on the ceiling. In addition to that, ultrasonic sensors are installed to detect obstacles around OdCR's way. Experimental studies are conducted to test the functionality of the system.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.691-698
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• 2015

Inertial Navigation Systems (INS) are widely used as the main navigation device for aircraft. To get the initial attitude, the INS requires the initial alignment before navigation starts. An aircraft also needs an engine test procedure that causes some vibrations before flight. An INS can't be aligned in a vibration environment so the initial alignment is performed before the aircraft engine test. Therefore, the initial alignment time of an INS has been a major factor in limiting an aircraft's takeoff response time. In this paper, we designed an initial alignment algorithm that can be executed even in disturbances such as aircraft run-up. We demonstrated verification of the algorithm that is embedded on the real INS and testing methods to evaluate the alignment of the INS. We also analyzed the test results of the proposed initial alignment algorithm that is performed during a real aircraft run-up.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.744-749
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• 2012

In this paper, we suggest that how to improve an accuracy of mobile robot's localization by using the sensor network information which fuses the machine vision camera, encoder and IMU sensor. The heading value of IMU sensor is measured using terrestrial magnetism sensor which is based on magnetic field. However, this sensor is constantly affected by its surrounding environment. So, we isolated template of ceiling using vision camera to increase the sensor's accuracy when we use IMU sensor; we measured the angles by pattern matching algorithm; and to calibrate IMU sensor, we compared the obtained values with IMU sensor values and the offset value. The values that were used to obtain information on the robot's position which were of Encoder, IMU sensor, angle sensor of vision camera are transferred to the Host PC by wireless network. Then, the Host PC estimates the location of robot using all these values. As a result, we were able to get more accurate information on estimated positions than when using IMU sensor calibration solely.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1448-1456
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• 1999

In this paper, we propose a new technique for path-following of the wheeled mobile robot systems with nonholonomic constraints using a path-observer. We discuss the path-following problems of the nonholonomic mobile robot systems which have two nonsteerable, independently driven wheels with the various initial conditions such as a position, a heading angle, and a velocity. It is shown that the performance of dynamic path-following importantly is affected by the intial conditions. Particularly, if the initial conditions become more distant from the desired path and the desired velocity become faster, the system is shown to have worse performance and small time local stable. To find the controllable and stable control for path-following with various initial configuration, we propose the path-observer which can be used for control of the stable path-following of nonholonomic mobile robot system with the various initial conditions. The proposed scheme exhibits the efficient path-following properties for nonholonomic mobile robot in any intial conditions. The simulation results demonstrate the effectiveness of the proposed method for dynamic path-following tasks with the various initial conditions.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.368-371
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• 2008

홈 네트워크내에서 Always-on 기기 특성으로 인하여 불필요한 에너지를 소비하는 경우가 전체 소모전력량의 60%이상을 차지한다. 그러므로 이러한 에너지 소비를 줄일 수 있는 방안에 대한 연구의 필요성이 점차 증대되고 있으며, 본고에서 연구한 Ethement 기반의 트래픽량에 의한 대기모드 전환 알고리즘은 에너지 절감에 매우 유용한 연구기술이라 할 수 있다. 이에, 본고에서는 idle time때의 네트워크 에너지 소비를 절감하기 위한 대기전력 지원형 Green Ethernet Gateway시스템설계 및 구현방안과 시스템 대기모드상태를 최대한 연장하여 energy efficient효과를 향상시키기 위한 Proxying 기반 control policy를 제안한다. 일반적으로 홈네트워크의 네트워크 연결은 ethemet을 중심으로 이루어지며, 대부분 게이트웨이를 기반으로 그 연결이 구성된다. 그러나 홈네트워크의 일반적인 동작시간이 8시간 내외인데도 불구하고, 네트워크 연결을 위해서 full Power 상태를 유지해야하는 기존의 energy unaware기반의 게이트웨이 구조로는 에너지측면에서 막대한 에너지 낭비를 초래한다. 이에 본고에서는 게이트웨이에서의 에너지 절감을 위한 트래픽량 기반의 대기모드 지원형 시스템을 구현하고 실제 홈네트워크 적용을 통한 에너지 절약효과를 실험한다. 또한 활성모드, 대기모드간 전환을 효과적으로 하기 위한 layer 2,3 Packe기반의 지능형 Proxying 알고리즘을 이용한 control policy를 제안한다.

• Journal of Ocean Engineering and Technology
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• v.34 no.6
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• pp.475-480
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• 2020

Underwater operating platforms face difficulties regarding power supply and communications. To overcome these difficulties, this study proposes a hybrid surface and underwater vehicle (HSUV) and presents the development of the platform, control algorithms, and results of field tests. The HSUV is capable of supplying reliable power to the unmanned underwater vehicle (UUV) and obtaining data in real time by using a tether cable between the UUV and the unmanned surface vehicle (USV). The HSUV uses global positioning system (GPS) and ultra-short base line sensors to determine the relative location of the UUV. Way point (WP) and dynamic positioning (DP) algorithms were developed to enable the HSUV to perform unmanned exploration. After reaching the target point using the WP algorithm, the DP algorithm enables USV to maintain position while withstanding environmental disturbances. To ensure the navigation performance at sea, performance tests of GPS, attitude/heading reference system, and side scan sonar were conducted. Based on these results, manual operation, WP, and DP tests were conducted at sea. WP and DP test results and side scan sonar images during the sea trials are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.414-419
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• 2010

This paper describes the design and performance of a hovering AUV 'NOAH' constructed at Jeju National University. We analyse the dynamic performance of NOAH using simulation program and carry out depth control test at small basin. The main purpose of NOAH is to carry out fundamental tests on its attitude control and position control. Its configuration is similar to general ROV appearance for underwater works and dimension is $0.75m{\times}0.5m{\times}0.5m$. It has 4 thrusters of 450watt for longitudinal/lateral/vertical propulsion and is equipped with a pressure sensor for measuring water depth and a magnetic compass for measuring heading angle. The navigation of the vehicle is controlled by an on-board Pentium III-class computer, which runs with the help of the Windows XP operating system. These give us an ideal environment for developing various algorithm which are needed for developing and advanced hovering AUV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.801-804
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• 2003

The autopilot system of vessel is proposed to take service safety sorority, to elevate service efficiency, to decrease labor and to improve working environment. Ultimate purpose of it is to minimize the number of crew by guaranteeing economical efficiency of shipping service. Recently, the research is being achieving to compensate various nonlinear parameters of vessel and apply it is course keeping control, track keeping control, roll-rudder stabilization, dynamic ship positioning and automatic mooring control etc. using optimizing control technique. Relation between rudder angle controlled by steering machine of vessel and ship-heading angle, and load condition of ship are nonlinear, which affect various parameters of shipping service. The speed and direction of waves, velocity and quantity of wind, which also cause the non-linearity of it. Therefore the autopilot system of ship requires the robust control algorithm can overcome various non-linearity. On this paper, we design the autopilot system of ship, which overcome nonlinear parameters and disturbance of it using Fuzzy Algorithm, evaluate the proposed algorithm and its excellence through simulation

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1509-1513
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• 2003

The autopilot system of vessel is proposed to take service safety and security, to elevate service efficiency, to decrease labor and to improve working environment. Ultimate purpose of the proposed system is to minimize the number of crew by guaranteeing economical efficiency of shipping service. Recently, the research is being achieved to compensate various nonlinear parameters of vessel and apply it to course keeping control, track keeping control, roll-rudder stabilization, dynamic ship positioning and automatic mooring control etc. using optimizing control technique. Relation between rudder angle controlled by steering machine of vessel and ship-heading angle, and load condition of ship is nonlinear, which affects various parameters of shipping service. The speed and direction of waves, velocity and quantity of wind, which also cause the non-linearity of it. Therefore the autopilot system of ship requires the robust control algorithm can overcome various non-linearity. On this paper, we design the autopilot system of ship, which overcomes nonlinear Parameters and disturbance of it using Fuzzy Algorithm, evaluate the proposed algorithm and its excellence through simulation.