• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.345-354
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• 2005

A mobile manipulator - a serial connection of a mobile robot and a task robot - is a very useful system to achieve various tasks in dangerous environment, because it has the higher performance than a fixed base manipulator in terms of its operational workspace size as well as efficiency. A method for estimating the position of an object in the Cartesian coordinate system based upon the geometrical relationship between the image captured by 2-DOF active camera mounted on mobile robot and the real object, is proposed. With this Position estimation, a method of determining an optimal path for the mobile manipulator from the current position to the position of object estimated by the image information using homogeneous matrices. Finally, the corresponding joint parameters to make the desired displacement are calculated to capture the object through the control of a manipulator. The effectiveness of proposed method is demonstrated by the simulation and real experiments using the mobile manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2519-2523
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• 2003

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a corner, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding ultrasonic signals, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, the current presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.355-363
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• 2011

Transcoding in the wireless mobile network is an important mechanism that reduces the delay time and improves the stream processing capacity. Wireless mobile streaming media services, however, have such problems as congestion, interference and delay due to narrow network bandwidth and limited resources. These problems degrade not only Quality of Service (QoS) but also responsiveness of the streaming media service. To solve this problem, this paper proposes a object version transcoding method. The proposed method analyzes the object versions to construct the transcoding graph. This paper utilizes a reference rate-based control function for an efficient streaming, and measures MVDS(Multiple Version Delay Saving) for an efficient delay savings. The simulation results show that the proposed mechanism achieves improved performance in delay rate and cache hit rate compared with those of other existing methods.

• The Journal of Korea Robotics Society
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• v.1 no.1
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• pp.36-45
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• 2006

In this paper, we introduce visual contexts in terms of types and utilization methods for robust object recognition with intelligent mobile robots. One of the core technologies for intelligent robots is visual object recognition. Robust techniques are strongly required since there are many sources of visual variations such as geometric, photometric, and noise. For such requirements, we define spatial context, hierarchical context, and temporal context. According to object recognition domain, we can select such visual contexts. We also propose a unified framework which can utilize the whole contexts and validates it in real working environment. Finally, we also discuss the future research directions of object recognition technologies for intelligent robots.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.585-587
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• 1998

본 논문은 분산 환경에서 의미상의 클라이언트가 서버에게 서비스를 요청하는 방법인 Java의 RMI, CORBA 등에서 사용하는 원격 호출 방법과 Mobile Agent를 이용하여 서버상으로 직접 이동하여 서비스를 요청하는 방법을 비교하고 분산 시스템상에서의 두 가지 커뮤니케이션 메커니즘 중 상황에 따라 어느것을 사용하는 것이 더 나은 효율을 나타낼 수 있는가를 판단하고 이를 이용하여 구현 패러다임을 결정할 수 있는 메트릭을 제시하는 것을 그 목적으로 한다.

• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.350-356
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• 2020

Workers have been replaced by mobile manipulators for factory automation in recent years. One of the typical tasks for automation is that a mobile manipulator moves to a target location and picks and places an object on the worktable. However, due to the pose estimation error of the mobile platform, the robot cannot reach the exact target position, which prevents the manipulator from being able to accurately pick and place the object on the worktable. In this study, we developed an automatic alignment system using a low-cost camera mounted on the end-effector of a collaborative robot. Camera calibration and pose estimation methods were also proposed for the automatic alignment system. This algorithm uses a markerboard composed of markers to calibrate the camera and then precisely estimate the camera pose. Experimental results demonstrate that the mobile manipulator can perform successful pick and place tasks on various conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.915-919
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• 2003

This paper presents a fuzzy-motion-control based tracking algorithm of mobile robots, which uses the geometrical information derived from the active stereo-vision system mounted on the mobile robot. The active stereo-vision system consists of two color cameras that rotates in two angular dimensions. With the stereo-vision system, the center position and depth information of the target object can be calculated. The proposed fuzzy motion controller is used to calculate the tracking velocity and angular position of the mobile robot, which makes the mobile robot keep following the object with a constant distance and orientation.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.706-709
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• 2009

The informatization of Korea is accompanied by the great growth of new strategic export industry, as of mobile phone or semiconductor LCD. Speaking to the situation of mobile phone, Motorola swept over the American domestic market in the beginning of 1990s, digital mobile communication as CDMA developed swiftly in Korea. In 1996, the first year's CDMA users of Samsung were merely one million, nevertheless, the world's sales in the first half of this year is up to 92 million. In this p aper I design 3D application based on J2ME and implement a freely removable 3D object which happened in a 3D scen e by receiving the keyboard response of mobile device with WTK (Wireless ToolKit) simulator. It contains benefits of improvement of relative speed and high-level functionality such as scene graph, keyframe animation, etc.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.4
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• pp.365-371
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• 2009

A intelligent mobile hexapod robot with various types of sensors and wireless camera is introduced. We show this mobile robot can detect objects well by combining the results of active sensors and image processing algorithm. First, to detect objects, active sensors such as infrared rays sensors and supersonic waves sensors are employed together and calculates the distance in real time between the object and the robot using sensor's output. The difference between the measured value and calculated value is less than 5%. This paper suggests effective visual detecting system for moving objects with specified color and motion information. The proposed method includes the object extraction and definition process which uses color transformation and AWUPC computation to decide the existence of moving object. We add weighing values to each results from sensors and the camera. Final results are combined to only one value which represents the probability of an object in the limited distance. Sensor fusion technique improves the detection rate at least 7% higher than the technique using individual sensor.

• Journal of Information Processing Systems
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• v.16 no.5
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• pp.1214-1222
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• 2020

Pervasive augmented reality (AR) technology can be used to efficiently search for the required information regarding products in stores through text augmentation in an Internet of Things (IoT) environment. The evolution of context awareness and image processing technologies are the main driving forces that realize this type of AR service. One of the problems to be addressed in the service is that augmented objects are fixed and cannot be replaced efficiently in real time. To address this problem, a real-time mobile AR framework is proposed. In this framework, an optimal object to be augmented is selected based on object similarity comparison, and the augmented objects are efficiently managed using distributed metadata servers to adapt to the user requirements, in a given situation. To evaluate the feasibility of the proposed framework, a prototype system was implemented, and a qualitative evaluation based on questionnaires was conducted. The experimental results show that the proposed framework provides a better user experience than existing features in smartphones, and through fast AR service, the users are able to conveniently obtain additional information on products or objects.