• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.795-800
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• 2008

The paper presents research for the established experiment environment of multi vehicle robot, localization algorithm that is based on vehicle control, and path tracking. The established experiment environment consists of ultrasonic positioning system, vehicle robot, server and wireless module. Ultrasonic positioning system measures positioning for using ultrasonic sensor and generates many errors because of the influence of environment such as a reflection of wall. For a solution of this fact, localization algorithm is proposed to determine a location using vehicle kinematics and selection of a reliable location data. And path tracking algorithm is proposed to apply localization algorithm and LOS, finally, that algorithms are verified via simulation and experimental

• 로봇학회논문지
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• 제4권3호
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• pp.177-184
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• 2009

This paper presents an active assisted-living system in wireless sensor and actor network (WSAN) in which the mobile robot roles an actor. In order to provide assisted-living service to the elderly people, position recognition of the sensor node attached on the user and localization of the mobile robot should be performed at the same time. For the purpose, we use received signal strength indication (RSSI) to find the position of the person and ubiquitous sensor nodes including ultrasonic sensor which performs both transmission of sensor information and localization like global positioning system. Active services are moving to the elderly people by detecting activity sensor and visual tracking and voice chatting with remote monitoring system.

• 로봇학회논문지
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• 제8권1호
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• pp.37-42
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• 2013

In this paper, a localization algorithm and an autonomous controller for PETASUS system II which is an underwater vehicle-manipulator system, are proposed. To estimate its position and to identify manipulation targets in a structured environment, a multi-rate extended Kalman filter is developed, where map information and data from inertial sensors, sonar sensors, and vision sensors are used. In addition, a three layered control structure is proposed as a controller for autonomy. By this controller, PETASUS system II is able to generate waypoints and make decisions on its own behaviors. Experiment results are provided for verifying proposed algorithms.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.952-959
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• 2016

This paper proposes a novel indoor positioning system (IPS) that uses a calibrated camera sensor network and dense 3D map information. The proposed IPS information is obtained by generating a bird's-eye image from multiple camera images; thus, our proposed IPS can provide accurate position information when objects (e.g., the mobile robot or pedestrians) are detected from multiple camera views. We evaluate the proposed IPS in a real environment with moving objects in a wireless camera sensor network. The results demonstrate that the proposed IPS can provide accurate position information for moving objects. This can improve the localization performance for mobile robot operation.

• 전기학회논문지
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• 제62권3호
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• pp.387-394
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• 2013

A travel aid system for the visually impaired person is proposed by providing the position and heading information. The position and heading information is obtained from range difference localization estimator, and the information is notified to the visually impaired person by using braille display system. For the precise estimation of the position and heading information, we apply recently developed linear localization estimator which utilizes the instrumental variable method and the state augmentation method. The estimation results are compared with well-known Kalman filter through experiment.

• 로봇학회논문지
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• 제17권4호
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• pp.397-406
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• 2022

This paper presents an autonomous mobile robot (AMR) system and operation algorithms for logistic and factory facilities without magnet-lines installation. Unlike widely used AMR systems, we propose an EKF-based loosely coupled fusion of LiDAR measurements and visual markers. Our method first constructs occupancy grid and visual marker map in the mapping process and utilizes prebuilt maps for precise localization. Also, we developed a waypoint-based navigation pipeline for robust autonomous operation in unconstrained environments. The proposed system estimates the robot pose using by updating the state with the fusion of visual marker and LiDAR measurements. Finally, we tested the proposed method in indoor environments and existing factory facilities for evaluation. In experimental results, this paper represents the performance of our system compared to the well-known LiDAR-based localization and navigation system.

• 한국항공우주학회지
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• 제38권3호
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• pp.258-263
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• 2010

소리를 이용한 위치 추적은 마이크로폰을 이용하여 신호를 수집하고 수집된 신호로 부터 마이크로폰 간의 신호 도달 시간차를 추정한 뒤 추정된 시간차를 이용하여 소리의 발생 위치를 추정하는 과정을 거치게 된다. 실내 환경에서 이를 활용하기 위해서는 잡음과 반향음에 대한 강건성을 확보해야만 하는 제약이 따른다. 특히 실시간으로 구현하기 위해서는 계산의 효율성까지 고려되어야 한다. 본 논문에서는 네 개의 저가 콘덴서 마이크로폰을 이용하여 비용적인 측면과 계산량에서의 효율성을 모두 추구하였다. 네 개의 마이크로폰을 이용하여 마이크로폰 간의 소리 도달 시간차를 구하는 계산량을 줄였고 GCC-PHAT(Generalized Cross Correlation-Phase Transform) 알고리즘을 이용해서 강건성을 높였으며 iterative least square 방식을 이용하여 높은 정확도의 위치 데이터를 얻을 수 있었다.

• 한국통신학회논문지
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• 제39B권9호
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• pp.614-619
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• 2014

WSN (Wireless Sensor Networks)기반 보안 감시 시스템에서는 센서들이 수집한 이벤트 발생 정보를 전송함에 있어서 이벤트가 발생한 지역의 위치 정보를 함께 제공하는 것이 요구된다. 기존에 많은 연구가 진행되었던 2D기반 위치추적 기법들은 고도가 일정한 환경에서는 꽤 높은 정확도를 보이나, 높이 개념이 추가된 실제 환경에서는 많은 오류를 발생시킬 수 있다. 또한 기존의 3D 위치추적 기법들은 많은 참조노드를 요구하거나, 복잡한 수식 계산을 요구하는 문제점을 가지고 있다. 그러나 본 논문에서 고려하는 실내 보안 감시 시스템에서는 감지된 대상체가 침입자인지 여부를 판단하기 위한 대상체의 높이 예측만을 요구한다. 따라서 본 논문에서는 복잡한 수식 계산이나 많은 참조노드들을 요구하지 않는 대상체 높이예측 기법을 제안한다. 또한 제안 기법의 성능분석을 위하여 여러 가지 시나리오에서 예측 정확도를 측정하였다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.561-578
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• 2010

This study proposes a multi-level damage localization strategy to achieve an effective damage detection system for civil infrastructure systems based on wireless sensors. The proposed system is designed for use of distributed computation in a wireless sensor network (WSN). Modal identification is achieved using the frequency-domain decomposition (FDD) method and the peak-picking technique. The ASH (angle-between-string-and-horizon) and AS (axial strain) flexibility-based methods are employed for identifying and localizing damage. Fundamentally, the multi-level damage localization strategy does not activate all of the sensor nodes in the network at once. Instead, relatively few sensors are used to perform coarse-grained damage localization; if damage is detected, only those sensors in the potentially damaged regions are incrementally added to the network to perform finer-grained damage localization. In this way, many nodes are able to remain asleep for part or all of the multi-level interrogations, and thus the total energy cost is reduced considerably. In addition, a novel distributed computing strategy is also proposed to reduce the energy consumed in a sensor node, which distributes modal identification and damage detection tasks across a WSN and only allows small amount of useful intermediate results to be transmitted wirelessly. Computations are first performed on each leaf node independently, and the aggregated information is transmitted to one cluster head in each cluster. A second stage of computations are performed on each cluster head, and the identified operational deflection shapes and natural frequencies are transmitted to the base station of the WSN. The damage indicators are extracted at the base station. The proposed strategy yields a WSN-based SHM system which can effectively and automatically identify and localize damage, and is efficient in energy usage. The proposed strategy is validated using two illustrative numerical simulations and experimental validation is performed using a cantilevered beam.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권4호
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• pp.210-216
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• 2017

본 논문은 지구 자기장 기반의 지문인식과 추측 항법을 사용하여 실시간으로 실내 위치정보 서비스를 사용자에 제공할 수 있는 알고리즘 및 솔루션을 제안한다. 지자기장 값의 변화 추이와 사전에 입력된 지자기장 값의 유사도를 판별하여 초기 위치를 추정하였으며 초기 위치에서 지자기장 지문인식과 추측 항법 상호 보정을 통해 보다 연속적인 이동 위치 추정을 함으로서 일부 5m가 넘어가는 지구 자기장의 최대 오차와 추측 항법의 누적 오차를 개선하였다. 그 뿐만 아니라 본 기법은 기존 지문인식 방법과는 달리 무선랜 AP등 인프라 구축을 제거하여 보다 경제적인 서비스 제공을 가능하게 한다.