• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.529-536
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• 2004

Autonomous navigation of an indoor mobile robot using the global ultrasonic system is presented in this paper. Since the trajectory error of the dead-reckoning navigation grows with time and distance, the autonomous navigation of a mobile robot requires to localize the current position of the robot, so that to compensate the trajectory error. The global ultrasonic system consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers on the mobile robot has the similar structure with the well-known satellite GPS(Global Positioning System), and it is useful for the self-localization of an indoor mobile robot. The EKF(Extended Kalman Filter) algorithm for the self-localization is proposed and the autonomous navigation based on the self-localization is verified by experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.2
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• pp.145-151
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• 2003

A global ultrasonic sensor system for self-localization of a mobile robot is proposed in this paper. The global ultrasonic sensor system consists of three or more ultrasonic transmitters fixed at some positions in the world coordinate and receivers in the moving coordinate of a mobile robot. In this global sensor system it is easy to get state vector of the mobile robot in the world coordinate from the distance information between each ultrasonic transmitter and receiver. An extended kalman filter algorithm is used to process the noisy ultrasonic signal and to estimate the state vector. In case of using several independent ultrasonic transmitters, it is necessary to avoid the cross talk among the ultrasonic waves and to synchronize between each ultrasonic transmitter and receiver. The small sized radio frequency modules are adopted to solve the cross talk and the synchronization problem Computer simulation and experiments are carried out to verify the effectiveness of the proposed ultrasonic sensor system.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.71-87
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• 2015

Mobile users want to be provided with undisrupted network services when they navigate on the Next-Generation (NG) wireless networks. For that, interlocking with a heterogeneous network is important, but there have been few studies on the method for guaranteeing global mobility. Thus, this paper proposes the Proxy-LMA technique, the mobile IP-based global inter-networking system, to enhance global mobility and interoperability within the Next-Generation (NG) network environment. The purpose of the proposed Proxy-LMA system is to expand the boundary of the mobility with regards to the existing mobility management protocol (PMIPv6 and MIPv6) in order to guarantee global mobility and interoperability within the heterogeneous network environment. The results of the performance evaluation showed that the proposed Proxy-LMA system was more efficient than other methods from the standpoint of signaling cost and delay in the heterogeneous network environment.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.846-851
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• 2004

In this paper, we propose a global ultrasonic system for the self-localization and autonomous navigation of indoor mobile robots. The ultrasonic sensor is regarded as the most cost-effective ranging system among the possible alternatives, and it is widely used for general purpose, since it requires simple electronic drivers and has relatively high accuracy. The global ultrasonic system presented in this paper consists of four or more ultrasonic generators fixed at reference positions in the global coordinates of an indoor environment and two receivers mounted on the mobile robots. By using the RF (Radio Frequency) modules added to the ultrasonic sensors, the robot is able to control the ultrasonic generation and to obtain the critical distances from the reference positions, which are required in order to localize is position in the global coordinates. A kalman filter algorithm designed for the self-localization using the global ultrasonic system and the experimental results of the autonomous navigation are presented in this paper.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2421-2423
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• 2002

A global ultrasonic sensor system for self-localization of an indoor mobile robot is proposed in this paper. By the global ultrasonic sensor system, it is meant several ultrasonic transmitters fixed at some positions in the world coordinate and the receiver in the moving coordinate of a mobile robot. In order to achieve the synchronization between an ultrasonic transmitter and receiver and to avoid the crosstalk among the ultrasonic transmitters, simple radio frequency transmitters and receivers are adopted. Experiments are carried out to verify the effectiveness of the proposed ultrasonic sensor system.

• Journal of Information Technology Applications and Management
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• v.24 no.2
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• pp.81-96
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• 2017

Forecasting long-term mobile service demand is inevitable to establish an effective frequency management policy despite the lack of reliability of forecast results. The statistical forecasting method has limitations in analyzing how the forecasting result changes when the scenario for various drivers such as consumer usage pattern or market structure for mobile communication service is changed. In this study, we propose a dynamic model of the mobile communication service market using system dynamics technique and forecast the future demand for long-term mobile communication subscriber based on the dynamic model, and also experiment on the change pattern of subscriber demand under various scenarios.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.318-324
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• 2006

The mobile manipulator is expected to work in partially defined or unstructured environments. In our global/local approach to path planning, joint trajectories are generated for a desired Cartesian space path, designed by the global path planner. For a local path planner, inverse kinematics for a redundant system is used. Joint displacement limit for the manipulator links is considered in the motion planner. In an event of failure to obtain feasible trajectories, the task cannot be accomplished. At the point of failure, a deviation in the Cartesian space path is obtained and a replanner gives a new path that would achieve the goal position. To calculate the deviation, a nonlinear optimization problem is formulated and solved by standard Sequential Quadratic Programming (SQP) method.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.75-82
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• 2016

Visible light communication (VLC) using LED lamps is suitable for implementing an indoor positioning system in an indoor environment where the global positioning system (GPS) signal does not reach. In this paper, we present an indoor positioning system for mobile robots using a VLC beacon and fuzzy rules. This system consists of an autonomous mobile robot, VLC modules, and device application software. Fuzzy rules are applied to plan the global and local paths along which the mobile robot navigates indoors. The VLC transmitter modules are attached to the wall or the ceiling as beacons to transmit their own location information. The variable pulse position modulation (VPPM) algorithm is used to transmit data, which is a new modulation scheme for VLC providing a dimming control mechanism for flicker-free optical communication. The mobile robot has a receiver module to receive the location information while performing its mission in the environment where VLC transmitters are deployed.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.6
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• pp.373-379
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• 2015

A hybrid navigation system is implemented to apply for a mobile robot. The hybrid navigation system consists of an inertial navigation system and a global positioning system. The inertial navigation system quickly calculates the position and the attitude of the robot by integrating directional accelerations, angular speed, and heading angle from a strap-down inertial measurement unit, but the results are available for a short time since it tends to diverge quickly. Global positioning system delivers position, heading angle, and traveling speed stably, but it has large deviation with slow update. Therefore, a hybrid navigation system uses the result from an inertial navigation system and corrects the result with the help of the global positioning system where an indirect feedback Kalman filter is used. We implement and confirm the performance of the hybrid navigation system through driving a car attaching it.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.27-39
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• 2018

Since the global positioning system (GPS) has been included in mobile devices (e.g., for car navigation, in smartphones, and in smart watches), the impact of personal GPS log data on daily life has been unprecedented. For example, such log data have been used to solve public problems, such as mass transit traffic patterns, finding optimum travelers' routes, and determining prospective business zones. However, a real-time analysis technique for GPS log data has been unattainable due to theoretical limitations. We introduced a machine learning model in order to resolve the limitation. In this paper presents a new, three-stage real-time prediction model for a person's daily route activity. In the first stage, a machine learning-based clustering algorithm is adopted for place detection. The training data set was a personal GPS tracking history. In the second stage, prediction of a new person's transient mode is studied. In the third stage, to represent the person's activity on those daily routes, inference rules are applied.