Kyungmin Kwak

Infrastructure-based Localization System using Underwater Wireless Sensor Network

In this paper, an infrastructure-based localization method using underwater wireless sensor network (UWSN) is addressed. A localization using the UWSN is necessary to widen the usage of underwater applications, however it is very difficult to establish the UWSN due to the restrictions of water. In this paper, to extend the usage of UWSN at the infrastructure, we propose a sophisticated UWSN localization method using the Received Signal Strength Indicator (RSSI) of the electromagnetic waves. During the electromagnetic waves propagating in underwater, there arises a lot of attenuation according to the distance, while the attenuation shows uniformity according to the distance. Using this characteristics, the localization system in underwater infrastructure is proposed and the experimental results show the effectiveness.

Development of underwater distance sensor using EM wave attenuation

In this paper, we discuss a novel underwater localization system using EM(Electro-Magnetic) wave. Maxwell equation and Friis transmission formula were reconstructed in terms of propagation constant and antenna property, then by combining these two formulas, we have defined the EM wave attenuation function over underwater distance. Using this function, we have developed an underwater sensor model for EM waves. Finally we organized an experimental environment and performed experiments for different frequencies, and through 2D localization using obtained sensor model, we meet with very confident results. The experimental results show a close correlation with the developed sensor model and the possibility of underwater localization systems using EM wave.

Development of Underwater Short-Range Sensor Using Electromagnetic Wave Attenuation

In this paper, we discuss a novel underwater short-range sensor using electromagnetic (EM) wave attenuation. We use the revised Friis-Shelkunoff formula to calculate the EM wave attenuation underwater as a function of distance. This requires knowledge of the antenna gain underwater, which is very different from the gain in air, and also the attenuation constant which depends on the water conductivity. We calibrated the gain and attenuation in a ranging experiment and also in a 2-D localization experiment. Both methods agreed, confirming that in situ calibration of a 2-D localization experiment is feasible. The localization results show good accuracy, validating the sensor model and showing that multipath effects can be made negligible in such an experiment.

Underwater sensor network using received signal strength of electromagnetic waves

We propose a scheme that uses the signal strength received from commercial RF sensors to determine the position of a sensor underwater. The scheme can give accurate position information and has fast update rate, but is limited to short sensor range with the signal identification problem. The infrastructure-based localization and a method that assigns frequency bands to RF sensors can be a solution to overcome this range limitation without loss of update rate or position accuracy. The RF sensor modules are used as ANs, and are easily identified by their channel assignments. To verify the proposed localization scheme, we organized an experimental environment and performed repetitive experiments to track the positions of mobile nodes and stationary nodes in 2D environments. The experimental results showed reliable localization accuracy with fast sampling rate and demonstrates the feasibility of localization that exploits EM wave attenuation.

Underwater 3-D Spatial Attenuation Characteristics of Electromagnetic Waves With Omnidirectional Antenna

In this paper, an underwater 3-D spatial attenuation model of electromagnetic waves is proposed to establish a position recognition system in underwater 3-D space using distance estimation. The distance estimation is based on signal attenuation characteristics of electromagnetic waves radiated through several omnidirectional antennas. Positions in underwater environments have been predominantly estimated by an ultrasonic position recognition system using travel time and phase difference. However, such a system provides inaccurate estimation on account of the multipath effect in a structured environment or complex environment with many obstacles. A position estimation method that uses signal attenuation of electromagnetic waves has been proposed to overcome this limitation. That method can precisely estimate position on a structured 2-D plane. In this paper, an existing underwater position estimation system based on electromagnetic waves is expanded into 3-D space using the Friis formula and plane wave equation, thereby classifying attenuation characteristics of electromagnetic waves into the effects of medium, radiation, and antenna. These effects are summarized to deduce the signal attenuation characteristics of electromagnetic waves in 3-D space. In addition, the relative position (R, Θ, Φ) and attitude (φ,θ, ψ) of transceiver antennas are used to define a coordinate system for 3-D estimation; moreover, an attenuation model is defined for individual factors in the coordinate system. A generalized attenuation model of an omnidirectional antenna in 3-D space is presented, and the validity of the proposed model is demonstrated through experiments. Based on the results, the proposed model demonstrates the potential application to an omnidirectional antenna and expansion into an attenuation model based on the 3-D position between random antennas.

3D underwater localization scheme using EM wave attenuation with a depth sensor

Previously, we proposed a scheme that determines the position of a remotely operated underwater vehicle (ROV) from the signal strengths of commercial radio-frequency sensors and antennas. This scheme provides accurate position information in a structured environment but is limited to two-dimensional (2D) environments because the radiation power of the antenna depends on the elevation angle between the sending and receiving antennas. To overcome this problem, we propose a 3D localization scheme that considers the electromagnetic (EM) wave attenuation over the range of reliable elevation angles. In order to determine the reliable elevation scope, we analyzed the radiation patterns of dipole antennas. The feasibility of our approach is demonstrated in distance estimation and 3D localization experiments by varying the distance and elevation angle. Encouraged by these results, we constructed an underwater wireless sensor network in the experimental basin, and performed ROV position tracking with the depth sensor. The scheme achieved reliable localization accuracy at a fast sampling rate, demonstrating the feasibility of exploiting EM wave attenuation in localization.

Underwater E-plane Attenuation Model of Omnidirectional Antenna Using Half Power Beam Width (HPBW)

In this paper, we use the characteristics of electromagnetic waves underwater attenuation for estimating linear distance between a transmitting node and receiving node, and research underwater vertical plane attenuation model for constructing the underwater localization system. The underwater localization of 2 dimensional with the plane attenuation model in the horizontal plane (H-plane) was proposed previous research. But for the 3 dimensional underwater localization, the additional vertical plane (E-plane) model should be considered. Because the horizontal plane of omnidirectional antenna has the same attenuation tendency in x-y plane according to the distance, whereas in vertical plane shows an irregular pattern in x-z plane. For that reason, in the vertical plane environment, the attenuation should be changed by the position and inclination. Hence, in this paper the distance and angle between transmitting and receiving node are defined using spherical coordinate system and derive an antenna gain pattern using half power beam width (HPBW). The HPBW is called a term which defines antennas performance between isotropic and other antennas. This paper derives omnidirectional antennas maximum gain and attenuation pattern model and define vertical planes gain pattern model using HPBW. Finally, experimental verifications for the proposed underwater vertical planes attenuation model was executed.In this paper, we use the characteristics of electromagnetic waves underwater attenuation for estimating linear distance between a transmitting node and receiving node, and research underwater vertical plane attenuation model for constructing the underwater localization system. The underwater localization of 2 dimensional with the plane attenuation model in the horizontal plane (H-plane) was proposed previous research. But for the 3 dimensional underwater localization, the additional vertical plane (Eplane) model should be considered. Because the horizontal plane of omnidirectional antenna has the same attenuation tendency in x-y plane according to the distance, whereas in vertical plane shows an irregular pattern in x-z plane. For that reason, in the vertical plane environment, the attenuation should be changed by the position and inclination. Hence, in this paper the distance and angle between transmitting and receiving node are defined using spherical coordinate system and derive an antenna gain pattern using half power beam width (HPBW). The HPBW is called a term which defines antenna’s performance between isotropic and other antennas. This paper derives omnidirectional antenna’s maximum gain and attenuation pattern model and define vertical plane’s gain pattern model using HPBW. Finally, experimental verifications for the proposed underwater vertical plane’s attenuation model was executed.

Manta ROV docking sequence using 3-D Omni-directional antenna's signal attenuation

In this paper, we discuss underwater ROV (Remote Operated Vehicle)s docking method using the power attenuation with EM waves which called RSS (Received Signal Strength). The Currently Docking methods are widely use with Vision approach, INS+SONAR and Magnetic waves. Most of ROV used INS+SONAR, it has great property for traveling in underwater. But used in closed area. This method occur Multipath effect. So when we use in closed area like ROV docking, there are no method with great resolution. So we focused EM waves RSS with Omni-directional antenna. In this paper, we develop the process for ROV (Manta)s docking method using the Omni-directional antennas 3-D EM waves attenuation pattern. The basic model for 3-D attenuation pattern is adapted in docking algorithm. And we proceed the experiment for confirm feasibility of guide the ROVs docking path.

3D underwater localization using EM waves attenuation for UUV docking

In this paper, we propose the underwater localization scheme for unmanned underwater vehicle (UUV) docking through the received signal strength (RSS) of electromagnetic (EM) waves sensors. By using the advantages of EM waves characteristics in water, this sensor can not only measure the distance with low environmental noise, but also guarantee precise localization performance with high sampling rates. In this localization scheme, an underwater wireless sensor network (UWSN) is constructed at target docking place using the sets of RF sensors. This UWSN functions as an artificial landmark during UUV docking. This localization process is operated in the framework of extended Kalman filter (EKF), and iterated during the docking procedure. The proposed scheme is verified by using the trajectory tracking experiment during UUV docking procedure.

Underwater Localization using RF Sensor and INS for Unmanned Underwater Vehicles

In this paper, we propose an underwater localization scheme through the fusion of an inertial navigation system (INS) and the received signal strength (RSS) of electromagnetic (EM) wave sensors to guarantee precise localization performance with high sampling rates. In this localization scheme, the INS predicts the pose of the unmanned underwater vehicle (UUV) by dead reckoning at every step, and the RF sensors corrects the UUV position functions using the Earth-fixed reference when the UUV is located in underwater wireless sensor networks (UWSN). The localization scheme and state modeling were conducted in the extended Kalman filter framework, and UUV localization experiments were conducted in a basin environment. The scheme achieved reliable localization accuracy during long-term navigation, demonstrating the feasibility of exploiting EM wave attenuation as Earth-fixed reference sensors.