Geomagnetic Sensor Research Articles

Research on Ground Calibration Technology for Geomagnetism Sensors

The measurements of geomagnetism sensors are often affected by self-factors, install-factors and environment factors, therefore they often exist error and cause measurement accuracy reduction. Focus on these problems, this paper analyse existing ground calibration algorithms and their merits and demerits respectively. Besides, a comprehensive geomagnetism sensor error model is presented. Based on this model, a least square method based ellipsoid fitting calibration and compensation algorithm is presented. The experiment results show that this novel calibration algorithm can effectively restrain and compensate geomagnetism signal measurement error.

Construction of an Overhauser magnetic gradiometer and the applications in geomagnetic observation and ferromagnetic target localization

The proton precession magnetometer with single sensor is commonly used in geomagnetic observation and magnetic anomaly detection. Due to technological limitations, the measurement accuracy is restricted by several factors such as the sensor performance, frequency measurement precision, instability of polarization module, etc. Aimed to improve the anti-interference ability, an Overhauser magnetic gradiometer with dual sensor structure was designed. An alternative design of a geomagnetic sensor with differential dual-coil structure was presented. A multi-channel frequency measurement algorithm was proposed to increase the measurement accuracy. A silicon oscillator was adopted to resolve the instability of polarization system. This paper briefly discusses the design and development of the gradiometer and compares the data recorded by this instrument with a commonly used commercially Overhauser magnetometer in the world market. The proposed gradiometer records the earth magnetic field in 24 hours with measurement accuracy of ± 0.3 nT and a sampling rate of 3 seconds per sample. The quality of data recorded is excellent and consistent with the commercial instrument. In addition, experiments of ferromagnetic target localization were conducted. This gradiometer shows a strong ability in magnetic anomaly detection and localization. To sum up, it has the advantages of convenient operation, high precision, strong anti-interference, etc., which proves the effectiveness of the dual sensor structure Overhauser magnetic gradiometer.

THE DESIGN AND IMPLEMENTATION OF INDOOR LOCALIZATION SYSTEM USING MAGNETIC FIELD BASED ON SMARTPHONE

Abstract. Sufficient signal nodes are mostly required to implement indoor localization in mainstream research. Magnetic field take advantage of high precision, stable and reliability, and the reception of magnetic field signals is reliable and uncomplicated, it could be realized by geomagnetic sensor on smartphone, without external device. After the study of indoor positioning technologies, choose the geomagnetic field data as fingerprints to design an indoor localization system based on smartphone. A localization algorithm that appropriate geomagnetic matching is designed, and present filtering algorithm and algorithm for coordinate conversion. With the implement of plot geomagnetic fingerprints, the indoor positioning of smartphone without depending on external devices can be achieved. Finally, an indoor positioning system which is based on Android platform is successfully designed, through the experiments, proved the capability and effectiveness of indoor localization algorithm.

Eliminating drift of the head gesture reference to enhance Google Glass-based control of an NAO humanoid robot

This article presents a strategy for hand-free control of an NAO humanoid robot via head gesture detected by Google Glass-based multi-sensor fusion. First, we introduce a Google Glass-based robot system by integrating the Google Glass and the NAO humanoid robot, which is able to send robot commands through Wi-Fi communications between the Google Glass and the robot. Second, we detect the operator’s head gestures by processing data from multiple sensors including accelerometers, geomagnetic sensors and gyroscopes. Next, we use a complementary filter to eliminate drift of the head gesture reference, which greatly improves the control performance. This is accomplished by the high-pass filter component on the control signal. Finally, we conduct obstacle avoidance experiments while navigating the robot to validate the effectiveness and reliability of this system. The experimental results show that the robot is smoothly navigated from its initial position to its destination with obstacle avoidance via the Google Glass. This hands-free control system can benefit those with paralysed limbs.

Reliable vehicle type recognition based on information fusion in multiple sensor networks

With the purpose to improve the real-time performance and accuracy of vehicle type recognition in complex traffic scenes, this paper proposed an information fusion based vehicle type recognition method. Firstly, the multiple sensor network built of geomagnetic sensors is described, whose characteristics include easy deployment and being budget friendly. Then, the vehicle type recognition method for the proposed multiple sensor network is applied. The main innovation of the method is matching the data collected by multiple sensors to form a fusion feature waveform for a single vehicle. Finally, the experimental results showed that the proposed method had 95% accuracy for small vehicles (Passenger vehicles and Sport utility vehicles) and 90% accuracy for large vehicles (Buses and Vans) approximately, which can provide a reference for multiple sensor network design and traffic data collection.

Estimation of joint center and measurement of finger motion by inertial sensors.

The authors developed a wearable finger motion measurement system using inertial and geomagnetic sensors. Using this system, motion and posture of the hands and fingers can be measured. However, the joint center and segment axis cannot be accurately measured in a previous study using the sensors. Therefore, the authors proposed a method of estimating the joint center and segment lengths. This method utilizes the fact that the calculation formula of the rotational acceleration in the sensor's coordinate system is the vector product. However, because the vector product is irreversible, the rotation center was calculated by using a position vector placed on an intersection line of two planes constituted by rotational acceleration. As a result of the verification, estimation error was small. In addition, finger motion was measured using posture measurement and rotation center estimation. This measured motion, joint angle and segment lengths estimated by the finger motion measurement system were compared with a motion capture system. As a result, the initial MP and PIP joint angles had some differences, but there was no difference for the MP and PIP joint angles during movement and the other joint angles. Therefore, we need to improve the estimation method of the PIP and DIP joint centers.

결합 가능한 모듈형 4족 로봇의 설계 및 작업 계획에 대한 연구

최근 다양한 환경에서 지능형 로봇의 안정된 이동과 작업계획에 대한 연구가 이루어지고 있다. 본 논문에서는 상하 결합가능한 구조의 4족 로봇의 설계 및 작업 계획방법을 제안한다. 제안하는 4족 로봇은 리니어 모터를 이용하여 다리 길이를 조절하고, 팔각뿔 형태의 도킹모듈을 이용하여 상하 결합과 분리가 가능하도록 설계하였다. 또한 로봇이 다양한 환경에서 안정된 이동과 정보 수집을 위하여 지자기 센서, PSD 센서, LRF 센서와 카메라를 사용하였다. 리니어 모터를 이용한 장애물 회피 동작방법과 상하 결합 동작방법을 제안하고 구현하였다. 로봇은 다리 길이를 조절하여 장애물을 극복하고, 두 대의 로봇이 상하 결합을 통하여 협력 작업방법을 제안하였다. 두 대의 4족 로봇이 상하 결합을 통하여 4족과 6족 보행을 하고, 상부 결합 로봇의 4개의 다리를 4개의 팔 또는 2개의 팔로 사용할 수 있으며, 결합된 로봇을 이용하여 물건 옮기기 작업을 구현하고, 각 동작들을 실제 실험으로 기능을 검증하였다. There are many researches to develop robots that improve its mobility and task planning to adapt in various uneven environments. In this paper, we propose the design method and task planning of quadruped robot which can have top-bottom docking structure. The proposed quadruped robot is designed to adjust leg length using linear actuators and perform top-bottom docking and undocking using octagonal cone shaped docking module. Also, to stable walking and information gathering in the various environments, a geomagnetic sensor, PSD sensor, LRF sensor and camera. We propose an obstacle avoidance method and the topbottom docking algorithm of the two quadruped robots using linear actuator. The robot can overcome obstacles using adjusting leg length and activate the top-bottom docking function. The top-bottom docking robots of two quadruped robot can walk 4 legged walking and 6 legged walking, and use 4 arms or 2 arms the upper. We verified that the docking robots can carry objects using 4 leg of the upper robot.

Overhauser Geomagnetic Sensor Based on the Dynamic Nuclear Polarization Effect for Magnetic Prospecting.

Based on the dynamic nuclear polarization (DNP) effect, an alternative design of an Overhauser geomagnetic sensor is presented that enhances the proton polarization and increases the amplitude of the free induction decay (FID) signal. The short-pulse method is adopted to rotate the enhanced proton magnetization into the plane of precession to create an FID signal. To reduce the negative effect of the powerful electromagnetic interference, the design of the anti-interference of the pick-up coil is studied. Furthermore, the radio frequency polarization method based on the capacitive-loaded coaxial cavity is proposed to improve the quality factor of the resonant circuit. In addition, a special test instrument is designed that enables the simultaneous testing of the classical proton precession and the Overhauser sensor. Overall, comparison experiments with and without the free radical of the Overhauser sensors show that the DNP effect does effectively improve the amplitude and quality of the FID signal, and the magnetic sensitivity, resolution and range reach to 10 pT/Hz@1 Hz, 0.0023 nT and 20–100 T, respectively.

Research on Stealthy Headphone Detector Based on Geomagnetic Sensor

A kind of stealth headphone detector based on geomagnetic sensor has been developed to deal with the stealth headphones which are small, extremely stealthy and hard to detect. The U.S. PNI geomagnetic sensor is chosen to obtain magnetic field considering the strong magnetic performance of stealth headphones. The earth’s magnetic field at the geomagnetic sensor is eliminated by difference between two geomagnetic sensors, and then weak variations of magnetic field is detected. STM8S103K2 is chosen as the central controlling chip, which is connected to LED, buzzer and LCD 1602. As shown by the experimental results, the probe is not liable to damage by the magnetic field and the developed device has high sensitivity, low False Positive Rate (FAR) and satisfactory reliability.

Fast and scalable 3D cyber-physical modeling for high-precision mobile augmented reality systems

Mobile augmented reality is an emerging technique which allows users to use a mobile device's camera to capture real-world imagery and view real-world physical objects and their associated cyber-information overlaid on top of imagery of them. One key challenge for mobile augmented reality is the fast and precisely localization of a user in order to determine what is visible in their camera view. Recent advances in Structure-from-Motion (SfM) enable the creation of 3D point clouds of physical objects from an unordered set of photographs taken by commodity digital cameras. The generated 3D point cloud can be used to identify the location and orientation of the camera relative to the point cloud. While this SfM-based approach provides complete pixel-accurate camera pose estimation in 3D without relying on external GPS or geomagnetic sensors, the preparation of initial 3D point cloud typically takes from hours to a day, making it difficult to use in mobile augmented reality applications. Furthermore, creating 3D cyber-information and associating it with the 3D point cloud is also a challenge of using SfM-based approach for mobile augmented reality. To overcome these challenges in 3D point cloud creation and cyber-physical content authoring, the paper presents a new SfM framework that is optimized for mobile augmented reality and rapidly generates a complete 3D point cloud of a target scene up to 28 times faster than prior approaches. Key improvements in the proposed SfM framework stem from the use of (1) state-of-the-art binary feature descriptors, (2) new filtering approach for accurate 3D modeling, (3) optimized point cloud structure for augmented reality, and (4) hardware/software parallelism. The paper also provides a new image-based 3D content authoring method designed specifically for the limited user interfaces of mobile devices. The proposed content authoring method generates 3D cyber-information from a single 2D image and automatically associates it with the 3D point cloud.

The Intelligent Storage Recording System Based On Cluster Bombs Testing and The Data Analysis

According to the bullet of cluster bombs in the separated Rotate- speed, dispensing overload, parachuteopening overload, landing overload and other parameters testing background, this paper designs a intelligent storage recording system which selects a the thin film geomagnetic sensor and photoelectric accelerometer as the sensitive unit, the intelligent storage recording system is mainly composed of the FPGA controller, FLASH memory, 12 bit high speed analog to digital converter. After live-fire test and numerical analysis, intelligent storage recording system can accurately obtain the whole process of flight parameter data from scatters to fall to the ground.

A Hybrid Positioning Scheme Exploiting Sensors and RSS of Wi-Fi Signals

As interests and demands for indoor positioning have recently increased, a positioning scheme utilizing the smartphone equipped with various sensors like an acceleration sensor and a geomagnetic sensor has been expected as a high potential and practical candidate for indoor positioning purpose. The acceleration sensor and the geomagnetic sensor are used for the estimation of travelled distance and the direction of movement of pedestrians, respectively. Although it provides very accurate positioning performance, the positioning scheme based only sensors tends to be affected by indoor environments like magnetic field of general indoor office building. In addition, the positioning error is apt to be accumulated as the travelled distance is increased. In this paper, therefore, a new positioning scheme is proposed to compensate the conventional positioning technology and to enhance the positioning performance. The proposed scheme consists with positioning based sensors, multi-lateration and WLAN-ID based on received signal strength (RSS) of Wi-Fi signals. The proposed scheme is evaluated with experiments at general building in university and the performance of the proposed scheme is superior to the conventional schemes such as a positioning scheme with only sensors and a positioning scheme based on RSS of Wi-Fi signals only.

Marketing Communication Menggunakan Augmented Reality pada Mobile Platform

Augmented Reality is a technology that can project objects from the virtual world to the real world. Augmented Reality continues to be developed so it can be easy to implement into various devices. However, the device must have a camera, VGA card, and the ability to process data that is high enough to be able to process and projecting graphical data that captured by the camera and displayed to the screen. Marker-based Augmented Reality is still better than Markerless Augmented Reality due to several issues such as disturbances in the geomagnetic sensor that is used to map the Y axis and Z device that belongs to the user.

Error Analysis and Algorithm Validation of Geomagnetic Sensor

Based on the fundamental principle of magnetic compass, the effect of interference and sensor errors on the magnetic azimuth measurement accuracy are analyzed. In order to eliminate the influence of geomagnetic sensor system error interference sources effectively, the paper puts forward a method of obtaining accurate heading angle and azimuth of magnetic compass, which is realized by converting magnetic components in the space coordinates to horizontal coordinate as well as adding an algorithm of eliminating carrier interference and software filter. The test of application system shows that data errors are greatly reduced after adding the anti-interference algorithm. The system testing errors is almost equal with Xiaomi phone at the same condition. It proves that this system is applicable to general navigation field.

Parking Information Monitoring and Management System Based on Internet of Things Technology

Collecting the parking information accurately and making good use of the existing parking spaces are keys to solve the problem of parking difficulty. Thus, the parking system based on internet of things technology was proposed. It used a geomagnetic sensor to collect the information of parking space and transmitted the information to the management center by using zigbee wireless communication technology. The center would release the information on the Internet. Via the website, vehicle owners could find a suitable parking space for their vehicle and know the shortest path to this parking. People can conveniently and accurately know the various information of each parking lot with the help of the system. Therefore, this system can effectively solve the problem of parking by monitoring and managing the parking information. It provides access to make good use of each parking space and improve urban transportation.

모바일용 저잡음 6축 관성센서 IC의 설계

In this paper, we designed 1 chip IC for 3-axis gyroscope and 3-axis accelerometer used for various IoT/M2M mobile devices such as smartphone, wearable device and etc. We especially focused on analysis of gyroscope noise and proposed new architecture for removing various noise generated by gyroscope MEMS and IC. Gyroscope, accelerometer and geo-magnetic sensors are usually used to detect user motion or to estimate moving distance, direction and relative position. It is very important element to designing a low noise IC because very small amount of noise may be accumulated and affect the estimated position or direction. We made a mathematical model of a gyroscope sensor, analyzed the frequency characteristics of MEMS and circuit, designed a low noise, compact and low power 1 chip 6-axis inertial sensor IC including 3-axis gyroscope and 3-axis accelerometer. As a result, designed IC has 0.01dps/√Hz of gyroscope sensor noise density. 논문 15-40-02-21 The Journal of Korean Institute of Communications and Information Sciences '15-02 Vol.40 No.02 http://dx.doi.org/10.7840/kics.2015.40.2.397 397 ※ 본 연구는 2013년도 정부(교육과학기술부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업(No. 2013R1A1A2012082) 및 미래창조과학부 및 정보통신기술연구진흥센터의 정보통신·방송연구개발사업(13-911-05-002, 다양한 IoT 서비스를 위한 액세스 네트워크 제어 기술)의 일환으로 수행하였음. First Author : School of Electrical & Electronic Engineering Yonsei University, chkim318@yonsei.ac.kr, 정회원 ° Corresponding Author : School of Electrical & Electronic Engineering Yonsei University, jmc@yonsei.ac.kr, 종신회원 논문번호:KICS2014-10-419, Received October 16, 2014; Revised November 6, 2014; Accepted November 6, 2014 The Journal of Korean Institute of Communications and Information Sciences '15-02 Vol.40 No.02

Fast Directional Handoff and lightweight retransmission protocol for enhancing multimedia quality in indoor WLANs

More and more mobile devices such as smartphones are being used with IEEE 802.11 wireless LANs (WLANs or Wi-Fi). However, mobile users are still experiencing poor service quality on the move due to the large handoff delay and packet loss problem. In order to reduce the delay, a new handoff scheme using the geomagnetic sensor embedded in mobile devices is proposed in this paper. The proposed scheme predicts the movement direction of a Mobile Station (MS) from the currently associated Access Point (AP) and performs active scanning with a reduced number of channels. In terms of the packet loss, a lightweight retransmission protocol is also proposed to minimize lost packets on Wi-Fi without producing a lot of acknowledgement packets. The proposed approaches are implemented on Android smartphones, and their performance is evaluated in a real indoor WLAN environment. The evaluation results demonstrate that the proposed schemes maintain seamless quality for real-time video even in an environment with frequent handoffs. Note that the proposed schemes are a client-only solution and do not require modification of the existing APs, which renders them very practical.

G1500206 GPSを用いた自律移動ロボットの補正手法に関する研究

Recently, application of robots has been required in disaster sites. Rescue robots were applied to disaster sites and they had obtained various results for the Great East Japan Earthquake. However, as a disadvantage the available range is limited because remote control type robots become impossible maneuvers if communication is terminated, due to a fault used range. We consider that is necessary for robots to autonomous work with the ability of self-determine action in order to avoid these problems. Generally, GPS is used for autonomous mobile robots that are working in outdoor environment. However, localization accuracy is depended strongly on the type of a GPS receiver. Moreover, it remains problems by blocking of signal that localization possible environments is limited with blocked as tall buildings or trees. This paper, present a novel control method using GPS and 3-axis geomagnetic sensor for autonomous mobile robot used in outdoor environment. The experimentally obtained results show that accuracy of the autonomous moving is improved by correcting position and orientation data measured from features results.

임베디드 기반의 다차원 위치정보 추출 및 저장시스템 개발

Lost fishing gears become a major cause of marine pollution, and many policy and technical efforts have been conducted for that. For efficient retrieving lost fishing gears in underwater, It is important to know the current position. Using GPS in the sub-sea environment is impossible and localization requires the use of special systems, and mobility due to water currents for underwater localization also has to be considered. In this paper, described with respect to the system for a self-generated location informations without using an external signal, such as a GPS and Sonar and storing them. Using the characteristics of the geomagnetic and INS principle, proposed informations and a way for estimating self position during movement. Embedded based system suggested and implemented in this study is tested for validating it's functionality. 키워드 : 수중 위치추정, 관성항법, 자이로센서, 가속도센서, 자자기센서 Key word : Underwater Localization, INS, Gyro Sensor, Acceleration Sensor, Geomagnetic Sensor Journal of the Korea Institute of Information and Communication Engineering 임베디드 기반의 다차원 위치정보 추출 및 저장시스템 개발

Application of motion sensors for beam-tracking of mobile stations in mmWave communication systems.

In a millimeter wave (mmWave) communication system with transmit/receive (Tx/Rx) beamforming antennas, small variation in device behavior or an environmental change can destroy beam alignment, resulting in power loss in the received signal. In this situation, the beam-tracking technique purely based on the received signal is not effective because both behavioral changes (rotation, displacement) and environmental changes (blockage) result in power loss in the received signal. In this paper, a motion sensor based on microelectromechanical systems (MEMS) as well as an electrical signal is used for beam tracking to identify the cause of beam error, and an efficient beam-tracking technique is proposed. The motion sensors such as accelerometers, gyroscopes, and geo-magnetic sensor are composed of an attitude heading reference system (AHRS) and a zero-velocity detector (ZVD). The AHRS estimates the rotation angle and the ZVD detects whether the device moves. The proposed technique tracks a beam by handling the specific situation depending on the cause of beam error, minimizing the tracking overhead. The performance of the proposed beam-tracking technique is evaluated by simulations in three typical scenarios.