• 로봇학회논문지
• /
• 제11권3호
• /
• pp.127-132
• /
• 2016

For a practical mobile robot team such as carrying out a search and rescue mission in a disaster area, the localization have to be guaranteed even in an environment where the network infrastructure is destroyed or a global positioning system (GPS) is unavailable. The proposed architecture supports localizing robots seamlessly by finding their relative locations while moving from a global outdoor environment to a local indoor position. The proposed schemes use a cooperative positioning system (CPS) based on the two-way ranging (TWR) technique. In the proposed TWR-based CPS, each non-localized mobile robot act as tag, and finds its position using bilateral range measurements of all localized mobile robots. The localized mobile robots act as anchors, and support the localization of mobile robots in the GPS-shadow region such as an indoor environment. As a tag localizes its position with anchors, the position error of the anchor propagates to the tag, and the position error of the tag accumulates the position errors of the anchor. To minimize the effect of error propagation, this paper suggests the new scheme of full-mesh based CPS for improving the position accuracy. The proposed schemes assuring localization were validated through experiment results.

• 제어로봇시스템학회논문지
• /
• 제17권10호
• /
• pp.1059-1066
• /
• 2011

This paper makes a close inquiry into ill-conditioning that may be occurred in wireless localization of the sensor nodes based on network signals in the wireless sensor network and provides the clue for solving the problem. In order to estimate the location of a node based on the range information calculated using the signal propagation time, LS (Least Squares) method is usually used. The LS method estimates the solution that makes the squared estimation error minimal. When a nonlinear function is used for the wireless localization, ILS (Iterative Least Squares) method is used. The ILS method process the LS method iteratively after linearizing the nonlinear function at the initial nominal point. This method, however, has a problem that the final solution may converge into a LM (Local Minimum) instead of a GM (Global Minimum) according to the deployment of the fixed nodes and the initial nominal point. The conditions that cause the problem are explained and an adaptive method is presented to solve it, in this paper. It can be expected that the stable location solution can be provided in implementation of the wireless localization methods based on the results of this paper.

• 제어로봇시스템학회논문지
• /
• 제15권3호
• /
• pp.293-299
• /
• 2009

This paper discusses an autonomous navigation system for urban environments. For the localization of the robot, EKF (Extended Kalman Filter) algorithm is used with odometry, angle sensor, and DGPS (Differential Global Positioning System) measurement. Especially in an urban environment, DGPS is often blocked by buildings and trees and the resulting inaccurate positioning prevents the robot from safe and reliable navigation. In addition to the global information from DGPS, the local information of the curb on the roadway is used to track a route when the global DGPS information is inaccurate. For this purpose, curb detection algorithm is developed and implemented in the developed navigation algorithm. Four different types of navigation strategies are developed and they are switched to adapt to different localization conditions according to the availability of DGPS and the existence of the curbs on the roadway. The experimental results show that the designed switching strategy improves the navigation performance adapting to the environment conditions.

• 대한금속재료학회지
• /
• 제47권11호
• /
• pp.773-785
• /
• 2009

Studies of a number of Cu-Zr amorphous alloys have demonstrated that those exhibiting greater plastic strain during homogeneous deformation at room temperature show lower global plasticity associated with inhomogeneous deformation in a typical compression test. Using a combination of experiments and molecular dynamics simulations, we clarify this seeming paradox between the homogeneous and inhomogeneous deformation by exploring the microstructural aspects in view of the structural disordering, disorder-induced softening, and shear localization and relate these findings to the global plasticity of bulk amorphous alloys. Additional analyses were conducted to derive a simple structural parameter that allows the prediction of the global plasticity of bulk amorphous alloys.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.26-27
• /
• 2015

In the trend of globalization and location transfer of existing production bases is still characterized by an extremely unstable status between different countries and different regions. The results are negative impacts on cost, quality and speed of project implementation, especially automobile industry which is one of the most complex manufacturing sectors. In order to overcome problems from Global Standardization of Production Line and its Localization, it is highly required comprehensive coordination among design of production equipment, production technology, space and interfaces. It is necessary to set up standard of production equipment and building for parallel progress, in order to complete production line in shortest time for launching product. In addition, this standard should keep flexibility with consideration of local situation which means "Glocalization."

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권1호
• /
• pp.215-236
• /
• 2017

Obtaining accurate location information is important in practical applications of wireless sensor networks (WSNs). The distance vector hop (DV-Hop) is a frequently-used range-free localization algorithm in WSNs, but it has low localization accuracy. Moreover, despite various improvements to DV-Hop-based localization algorithms, maintaining a balance between high localization accuracy and good stability and convergence is still a challenge. To overcome these shortcomings, we proposed an improved DV-Hop localization algorithm based on the bat algorithm (IBDV-Hop) for WSNs. The IBDV-Hop algorithm incorporates optimization methods that enhance the accuracy of the average hop distance and fitness function. We also introduce a nonlinear dynamic inertial weight strategy to extend the global search scope and increase the local search accuracy. Moreover, we develop an updated solutions strategy that avoids premature convergence by the IBDV-Hop algorithm. Both theoretical analysis and simulation results show that the IBDV-Hop algorithm achieves higher localization accuracy than the original DV-Hop algorithm and other improved algorithms. The IBDV-Hop algorithm also exhibits good stability, search capability and convergence, and it requires little additional time complexity and energy consumption.

• 전기학회논문지
• /
• 제59권1호
• /
• pp.197-203
• /
• 2010

The problem of location awareness in wireless sensor networks where nodes use GPS (Global Positioning System), remains challenging problem, when considering the required large energy consumption during the localization phase. In this paper we designed hardware for GPS based localization and propose a framework, called ELS, to consume low cost energy. In the ELS framework, sensor nodes are equipped with GPS. Because GPS spends large energy for position awareness, conventional localization algorithms cannot use GPS-device. We try to find a solution for efficient energy expenditure of GPS. Finally, we derive optimal transmission power of GPS data and a scheme of localization through experiment and simulation.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.2301-2306
• /
• 2005

Even if there are lots of researches on localization using 2D range finder in static environment, very few researches have been reported for robust real-time localization of mobile robot in uncertain and dynamic environment. In this paper, we present a new localization method based on ICP(Iterative Closest Point) algorithm for navigation of mobile robot under dynamic or uncertain environment. The ICP method is widely used for geometric alignment of three-dimensional models when an initial estimate of the relative pose is known. We use the method to align global map with 2D scanned data from range finder. The proposed algorithm accelerates the processing time by uniformly sampling the line fitted data from world map of mobile robot. A data filtering method is also used for threshold of occluded data from the range finder sensor. The effectiveness of the proposed method has been demonstrated through computer simulation and experiment in an office environment.

• 정보학연구
• /
• 제10권2호
• /
• pp.11-27
• /
• 2007

This thesis is analysing localization of human resources recruitment in the overseas investment of the Korean firms. The main results of the analysis can be summarized as follows: first, Korean overseas local corporations have achieved localization for physical workers. But localization above middle manager level is very poor. Second, local corporations are managed by the employee from Korean parent company. Third, parent company mentioned language ability, work process ability of local business, responsibility, leadership as selection basis for the workers in overseas local corporations. Localization propel strategy of local corporation human resources recruiting : (1) human resources recruiting strategy is the strategy of outsider. simple global human resources recruiting strategy is the recruiting of person dispatched from headquarter rather than local human resources (2) human resources recruiting strategy is the strategy of multidomestication. multidomestication human resources recruiting strategy is the strategy to use in case of stabilization in local area.

• Journal of information and communication convergence engineering
• /
• 제19권3호
• /
• pp.188-197
• /
• 2021

In military operations, an accurate localization system is required to navigate soldiers to their destinations, even in non-GPS environments. The global positioning system is a commonly used localization method, but it is difficult to maintain the robustness of GPS-based localization against jamming of signals. In addition, GPS-based localization cannot provide important terrain information such as obstacles. With the widespread use of embedded sensors, sensor-based pedestrian tracking schemes have become an attractive option. However, because of noisy sensor readings, pedestrian tracking systems using motion sensors have a major drawback in that errors in the estimated displacement accumulate over time. We present a group-based standalone system that creates terrain maps automatically while also locating soldiers in mountainous terrain. The system estimates landmarks using inertial sensors and utilizes split group information to improve the robustness of map construction. The evaluation shows that our system successfully corrected and combined the drift error of the system localization without infrastructure.