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A Modified Multiple Depth First Search Algorithm for Grid Mapping Using Mini-Robots Khepera

  • El-Ghoul, Sally;Hussein, Ashraf S.;Wahab, M. S. Abdel;Witkowski, U.;Ruckert, U.
    • Journal of Computing Science and Engineering
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    • v.2 no.4
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    • pp.321-338
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    • 2008
  • This paper presents a Modified Multiple Depth First Search algorithm for the exploration of the indoor environments occupied with obstacles in random distribution. The proposed algorithm was designed and implemented to employ one or a team of Khepera II mini robots for the exploration process. In case of multi-robots, the BlueCore2 External Bluetooth module was used to establish wireless networks with one master robot and one up to three slaves. Messages are sent and received via the module's Universal Asynchronous Receiver/Transmitter (UART) interface. Real exploration experiments were performed using locally developed teleworkbench with various autonomy features. In addition, computer simulation tool was also developed to simulate the exploration experiments with one master robot and one up to ten slaves. Computer simulations were in good agreement with the real experiments for the considered cases of one to one up to three networks. Results of the MMDFS for single robot exhibited 46% reduction in the needed number of steps for exploring environments with obstacles in comparison with other algorithms, namely the Ants algorithm and the original MDFS algorithm. This reduction reaches 71% whenever exploring open areas. Finally, results performed using multi-robots exhibited more reduction in the needed number of exploration steps.

A Destruction Pattern Analysis of a Turbo-Molecular Pump According to the Foreline Clamp Damage in an ICP Dry Etcher for 300 mm Wafers

  • Jeong, Jinyong;Lee, Intaek;Joo, Junghoon
    • Applied Science and Convergence Technology
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    • v.24 no.2
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    • pp.27-32
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    • 2015
  • We analyzed the destruction patterns of a turbo-molecular pump (TMP) resulting from its sudden exposure of a foreline to the atmospheric pressure due to a destruction of the foreline connecting clamp of an ICP dry etcher for 300 mm wafers during high-vacuum operation ($5{\times}10^{-6}$ Torr). Unlike in the case of view port's breakage, the TMP's rotor module was crashed inside the chamber. The primary damage resulted from the collision of the blades and stators, and the secondary damage resulted from the breaking of the rotor - driving shaft assembly. The fixing screws of the rotor and axial shaft were bent and broken when the TMP controller output the maximum current even after the crash event. Electrical power consumption analysis of the TMP power controller confirmed it. The stress distributions were analyzed by a finite element method using CFD-ACE+ multi physics software. Rotating inertia of each parts and kinetic energies were calculated as well. 68% of the rotational kinetic energy is deposited by the rotor - shaft module.

Design and Fabrication of PZT Disc Actuated Micro Pump for Bio-Applications (I): Optimal Design of Ring-shaped Flab Valve Module (바이오용 압전디스크방식 마이크로 펌프 설계 및 제작(I) -링형 플랩밸브 모듈의 최적설계-)

  • Kim, Hyung-Jin;Seo, Young-Ho;Kim, Byeong-Hee
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.3
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    • pp.355-361
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    • 2012
  • Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, it has some intrinsic disadvantages such as backward flow, pulsation of flow, low repeatability and producibility, and high cost. To overcome these limitation, a PZT disc actuated micro pump including a novel ring-shaped multi-flap check valve is introduced. To enhance the performance of the micro pump, the static behaviour of flap valve module and the micro fluidic behavior of fluids are numerically modelled and analyzed. As results of the numerical analysis, the optimal dimension and configuration of the ring-shaped multi flap valve are $1{\times}0.05$ mm and 2 (inlet side)${\times}1$ (outlet side) type. The obtained maximum flow rates and flow resolution are about 90 ml/min and 30 ${\mu}l$/stroke respectively.

PIV Analysis of the External Flow Field of Front End Cooling Pack System (PIV 유동 계측을 통한 자동차 프런트 엔드 쿨링 팩 시스템의 외부 유동특성 평가)

  • Heo, Hyung-Seok;Han, Chang-Pyung;Park, Kyoung-Suk;Lee, Gee-Soo;Bae, Suk-Jung;Won, Jong-Phil
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.103-110
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    • 2004
  • The major trend in global automotive market is changing drastically in the way that a vehicle FECPS(Front End Cooling Pack System) is designed and manufactured as an assembly part. The system can encompass many functions, be assembled into a vehicle as a module, and reduce the production cost as well as time. The FECPS consists of an impact beam, an aluminum condenser and a radiator, a carrier and a cooling fan with a BLDC motor. In order to predict the performance of a FECPS accurately, it is essential to properly model the air flow field through various heat exchangers, such as a condenser or a radiator. In this study, the flow field of the system is measured by a PIV(Particle Image Velocimetry) system. The result is compared with that measured with multi-channel anemometer.

Resource Allocation Algorithm for Multi-cell Cognitive Radio Networks with Imperfect Spectrum Sensing and Proportional Fairness

  • Zhu, Jianyao;Liu, Jianyi;Zhou, Zhaorong;Li, Li
    • ETRI Journal
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    • v.38 no.6
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    • pp.1153-1162
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    • 2016
  • This paper addresses the resource allocation (RA) problem in multi-cell cognitive radio networks. Besides the interference power threshold to limit the interference on primary users PUs caused by cognitive users CUs, a proportional fairness constraint is used to guarantee fairness among multiple cognitive cells and the impact of imperfect spectrum sensing is taken into account. Additional constraints in typical real communication scenarios are also considered-such as a transmission power constraint of the cognitive base stations, unique subcarrier allocation to at most one CU, and others. The resulting RA problem belongs to the class of NP-hard problems. A computationally efficient optimal algorithm cannot therefore be found. Consequently, we propose a suboptimal RA algorithm composed of two modules: a subcarrier allocation module implemented by the immune algorithm, and a power control module using an improved sub-gradient method. To further enhance algorithm performance, these two modules are executed successively, and the sequence is repeated twice. We conduct extensive simulation experiments, which demonstrate that our proposed algorithm outperforms existing algorithms.

Design and Implementation of File Access Control Module Based on Multi-Operating System (멀티 운영체제 기반의 파일 접근 제어 모듈 설계 및 구현)

  • Soh, Woo-Young
    • Convergence Security Journal
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    • v.7 no.4
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    • pp.123-131
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    • 2007
  • Recently, various threat and security incident are occurred for unspecified individuals, and this problem increases as the rapid of information sharing through Internet. The using of Information Security System such as IDS, Firewall, VPN etc. makes this problem minimal. However, professional knowledge or skill is needed in that case, normal user can't operate the Information Security System. This paper designs and implements File Access Control Module(FACM) to use easily for normal user against malicious threats and attacks. The FACM can exclude from malicious threats and attacks based on operation system rather than detection of threats and attacks. The FACM is working not only Windows System but also Linux System, and the FACM has effect on access control, integrity and non-repudiation for a file with an access control over files on the each OS that are used by multi-user.

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Multi-Function RFID Reader be based on ARM920T Platform (ARM920T 기반의 다기능 RFID Reader Platform 기술 개발)

  • 이상신;김영길
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.37-40
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    • 2004
  • This paper is about Multi-function RFID Reader Platform that receives RF TAC data and transfer data to HOST PC through Blue-Tooth USB, RS-232 and Ethernet. This Reader system is composed of RFID Module, ARM Processor, RS-232, US5 and Ethernet Interface, etc.. The information of Tag stretches the RFID module through the antenna and is received at the ARM processor. ARM processor accomplishes the facility to deliver these informations at the PC server using the Blue-tooth Interface for the wireless and the RS-232, USB and Ethernet MAC Interface for the wire.

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Development of RecurDyn Module for Wind Turbine Analysis Applying BEM Theory (BEM 이론을 적용한 풍력발전기 해석용 RecurDyn 모듈 개발)

  • Lim, Dae Guen;Yoo, Wan Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.2
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    • pp.115-120
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    • 2014
  • In this study, a module is developed for modeling and analyzing dynamic behavior of a wind turbine using RecurDyn, which is a commercial multi-body dynamics software developed by FunctionBay, Inc. The wind turbine consists of tower, nacelle, hub and blades. Tower and blades are regarded as flexible bodies for considering elastic effect using beam theory and spring force. In this paper, a constant speed wind was assumed and aerodynamic force is modeled using BEM theory. Dynamic analysis applying this aerodynamic force is carried out. To verify the validity of analysis results, these results are compared to those of GH-Bladed which is a commercial software for analyzing wind turbine system distributed by Garrad Hassan.

A Study on Orientation and Position Control of Mobile Robot Based on Multi-Sensors Fusion for Implimentation of Smart FA (스마트팩토리 실현을 위한 다중센서기반 모바일로봇의 위치 및 자세제어에 관한 연구)

  • Dong, G.H;Kim, D.B.;Kim, H.J;Kim, S.H;Baek, Y.T;Han, S.H
    • Journal of the Korean Society of Industry Convergence
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    • v.22 no.2
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    • pp.209-218
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    • 2019
  • This study proposes a new approach to Control the Orientation and position based on obstacle avoidance technology by multi sensors fusion and autonomous travelling control of mobile robot system for implimentation of Smart FA. The important focus is to control mobile robot based on by the multiple sensor module for autonomous travelling and obstacle avoidance of proposed mobile robot system, and the multiple sensor module is consit with sonar sensors, psd sensors, color recognition sensors, and position recognition sensors. Especially, it is proposed two points for the real time implementation of autonomous travelling control of mobile robot in limited manufacturing environments. One is on the development of the travelling trajectory control algorithm which obtain accurate and fast in considering any constraints. such as uncertain nonlinear dynamic effects. The other is on the real time implementation of obstacle avoidance and autonomous travelling control of mobile robot based on multiple sensors. The reliability of this study has been illustrated by the computer simulation and experiments for autonomous travelling control and obstacle avoidance.

Auto Sequencing User Interface for Mobile Robot Using Multi Sensor System (다중 센서 시스템을 이용한 이동로봇의 자동-절환 사용자 인터페이스)

  • Song, Tae-Houn;Park, Ji-Hwan;Park, Jong-Hyun;Jung, Soon-Mook;Hong, Soon-Hyuk;Kim, Gi-Oh;Jeon, Jae-Wook
    • 한국HCI학회:학술대회논문집
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    • 2008.02a
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    • pp.319-325
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    • 2008
  • In this paper, we develop the multi sensor system, to get the sufficient information of mobile robot's environment. Mobile robot user interface, based on multi sensor system, can choice a suitable sensor by low-cost multi sensors and then acquisition information from remote robot's workspace using auto sequencing user display function. This research of multi sensor system is consists of ultrasonic sensor, position sensing detector, and low-cost CMOS camera module.

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