• 제목/요약/키워드: Nominal Mechanism

검색결과 56건 처리시간 0.019초

Practical Ultraprecision Positioning of a Ball Screw Mechanism

  • Sato, Kaiji;Maeda, Guilherme Jorge
    • International Journal of Precision Engineering and Manufacturing
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    • 제9권2호
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    • pp.44-49
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    • 2008
  • This paper describes the problem of ultraprecision positioning with a ball screw mechanism in the microdynamic range, along with its solution. We compared the characteristics of two ball screw mechanisms with different table masses. The experimental results showed that the vibration resulting from the low stiffness of the ball screw degraded the positioning performance in the microdynamic range for the heavyweight mechanism. The proposed nominal characteristic trajectory following (NCTF) controller was designed for ultra precision positioning of the ball screw mechanism. The basic NCTF control system achieved ultra precision positioning performance with the lightweight mechanism, but not with the heavyweight mechanism. A conditional notch filter was added to the NCTF controller to overcome this problem. Despite the differences in payload and friction, both mechanisms then showed similar positioning performance, demonstrating the high robustness and effectiveness of the improved NCTF controller with the conditional notch filter. The experimental results demonstrated that the improved NCTF control system with the conditional notch filter achieved ultra precision positioning with a positioning accuracy of better than 10 nm, independent of the reference step input height.

부유식 해양플랜트 계류 체인의 면외굽힘 거동에 대한 연구 (A Study on Out-of-Plane Bending Mechanism of Mooring Chains for Floating Offshore Plants)

  • 임유창;김경수;정준모;강찬회
    • 대한조선학회논문집
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    • 제47권4호
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    • pp.580-588
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    • 2010
  • OPB(out-of-plane bending)-induced failure of mooring chain was firstly addressed by CALM (catenary anchor leg mooring)-type offloading buoy, located approximately one mile away from the bow of the Girassol FPSO which was installed offshore area of Angola in September 2001. This study deals with verifying the load transfer mechanism between the first free chain link and connected two chain links inside the chain hawse. OPB moment to angle variation relationships are proposed by extensive parametric study where the used design variables are static friction coefficients, proof test loads, nominal tension forces, chain link diameters, chain link grades and chain link types. The stress ranges due to OPB moments are obtained using nonlinear FEAs (finite element analyses). Final stress ranges are derived considering ones from IPT (in-plane tension) forces. Also a formula for OPB fatigue assessment is briefly introduced.

강도설계법으로 산정된 탄소섬유시트 보강 철근콘크리트 보의 공칭 휨모멘트 (Determination of Nominal Moment of Strengthening Beam with Carbon Fiber Sheets Using Strength Method)

  • 조백순;정진환;김성도;박대효;이우철
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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    • pp.593-598
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    • 2002
  • Routinely, strength method for the determination of the nominal moment of reinforced concrete beam is assumed to also be suitable for strengthening beams with carbon fiber sheets since typically strengthening beams compromise 98% by volume of reinforced concrete. Flexural capacity of strengthening beam is absolutely dependent upon the type of reinforcement materials, amount of reinforcement, anchoring system, adhesion capacity between reinforcement material and concrete. Therefore, it might be incorrect to use strength method for analysis and design of strengthening beam without considering the differences in the load-deflection curves, mechanism of failure, state of stress distribution, failure strain of the reinforcement. An flexural analysis based on force equilibrium and strain comparability has been developed for strengthening beam. Systematic experimental investigations are compared with analytical results. Then, the adaptation of strength method for strengthening beam have also been discussed.

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구두 형식의 전자적 브레인 스토밍이 인지적 자극에 미치는 영향에 대한 실증적 연구 (Empirical Validation for Verbal- EBS Effect to Cognitive Stimulation)

  • 김정욱;정종호
    • 품질경영학회지
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    • 제36권2호
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    • pp.67-84
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    • 2008
  • Given the industry's unprecedented attention and dedication of resources to voice recognition, this paper introduces and explores a novel idea generation technique whereby ideas are captured directly through verbalization rather than forcing group members to type ideas. A group simulator was used to measure the idea generation performance of individuals who input ideas verbally or via typing in the context of nominal and interacting groups. The results clearly indicate that verbal input represents a more desirable mechanism in a computer-mediated idea generation environment. Liberating group members from the keyboard produces remarkable performance gains. Verbalizing ideas helps individuals focus on analytical thinking and leverage group member ideas, ultimately facilitating the creation of ideas pools that are vastly superior in terms of quantity and quality. These effects were found across nominal and interacting groups. The implications of these results for future research and the design of technologies are discussed.

2관절 로봇팔의 공차로 인한 신뢰도 해석 (Reliability Analysis of a Two-Link Robot Manipulator Due to Tolerances)

  • 이세정
    • 대한기계학회논문집
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    • 제18권9호
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    • pp.2257-2264
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    • 1994
  • A method to evaluate the position performance for a stochastically defined planar robot manipulator is presented. Performance is defined as the operational reliability based upon the positional errors of the manipulator tip. An analytical method is developed and applied to a two-link robot manipulator through forward kinematics. This study includes uncertainties in the link length, pin center location and radial clearance. By virtue of the effective link length model, only the nominal manipulator model and statistical information on the uncertainties are required. The results from the analytical method is compared to those from the Monte Carlo simulation.

클러치기반의 선택적 구동방식을 이용한 배관로봇의 개발 (Development of In-Pipe Robot Using Clutch-Based Selective Driving Algorithm)

  • 김도완;노세곤;이정섭;이수환;최혁렬
    • 대한기계학회논문집A
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    • 제32권3호
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    • pp.223-231
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    • 2008
  • This paper introduces a robot called the MRINSPECT V (Multifunctional Robotic crawler for Inpipe in-SPECTion V) for the inspection of pipelines with a nominal 8-in inside diameter. Based on the mechanism of the previous model MRINSPECT IV, we developed a new MRINSPECT V by using the differential driving mechanism, so that just simply controlling the speed of each driving units helps the robot to travel effectively inside the pipelines. Furthermore, the robot uses clutches in transmitting driving power to wheels. This clutch mechanism enables MRINSPECT V to select the suitable driving method according to the shape of pipeline. In this paper, the critical points in design and construction of the proposed robot are described with the preliminary results to provide good mobility and increase the efficiency.

TC볼트의 스트리핑 메카니즘에 대한 실험적 연구 (Experimental study on stripping mechanism of tension controlled bolts)

  • 신근하
    • 한국생산제조학회지
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    • 제9권1호
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    • pp.111-118
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    • 2000
  • Over tightening experiments of the tension-controlled bolts are carried out and the stripping mechanism is reviewed base on the observed results. There are two modes of bolt failure due to the over tightening : one the fracture of the bolt the other the thread stripping Bifurcation between these two modes is rather delicate but it seems being related with the elastic flexibility of the bolt which depends upon the unused thread length. The fracture mode occurs in the bolts with good flexibility while the latter with bad one. According to the ISO Standard some meter coarse threads like M20 and M22 have the same pitch which causes bigger fastener to less resistance in shear and bending compared with the smaller one. however since UNC thread system adapts different pitch for different nominal diameter unified coarse threads show better stripping resistance than their corresponding meter threads.

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정밀조립을 위한 병렬다관절 구조를 가진 로봇손목기구의 개발 (Development of a parallel link typed wrist for robotic precision assembly)

  • 문창렬;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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    • pp.281-286
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    • 1993
  • In this paper, a parallel link typed wrist is developed for robotic precision assembly. The developed wrist can make the corrective motion required for compensating lateral and tilting errors. The mechanism of this wrist is one example of a motion simulator generating 6 DOF motion in space by 6 actuators connected in paralle. To make the wrist more compact, miniature DC motors containing reduction gears and servo system were used. The parallel link architecture enables a high positioning accuracy and high nominal load capacity. In this study, inverse kinematic problem is solved by using a Denavet-Hartenberg method and a simulational result about workspace of the proposed parallel mechanism is obtained.

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가동 코일 및 DC Motor로 작동되는 유연한 빔의 운동 특성 해석 (Dynamic Characteristic Analysis of a Flexible Beam Actuated by Moving Coil and DC Motor)

  • 유화준;정원택;남윤수
    • 산업기술연구
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    • 제19권
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    • pp.15-23
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    • 1999
  • Active damping system is generally used for the vibration suppression and precise motion control for the flexible structure. This application can be easily found on the space structure and driving mechanism of optical storage devices. Although a control system using the flexible structure has many advantages over using rigid mechanism in driving energy saving, system weights, and etc., more complex and precise control strategies are required. A position control system using flexible structure and the concept of active damper is designed and manufactured, which is driven by slide DC motor and moving coil motor located at the tip of the flexible beam. Dynamic characteristics of this system are investigated by analytic and experimental ways. By the comparison of those two results, a nominal reference model for this system is proposed.

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Lyapunov Redesign 기법을 이용한 태양광 발전 시스템의 안정한 적응형 컨버터 제어기법 (The Stable Adaptive Converter Control Method of Photovoltaic Power Systems using Lyapunov Redesign Approach)

  • 조현철;박지호;김동완
    • 전기학회논문지P
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    • 제61권4호
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    • pp.161-167
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    • 2012
  • Energy conversion systems such as power inverters and converters are basically significant in establishing photovoltaic power systems to enhance power effectiveness. This paper proposes a new converter control method by using the Lyapunov redesign approach. We construct the proposed control mechanism linearly composed of nominal control and auxiliary control laws. The former is generally designed through a well-known power electronic technology and the latter is implemented to compensate real-time control error due to uncertain natures of converter systems in practice. For realizing adaptive control capability in the proposed control mechanism, a control parameter vector is estimated by utilizing a steepest descent based optimization method. We carry out numerical simulation with Matlab(c) software to demonstrate reliability of the proposed converter control system and conduct a comparative study to prove its superiority by comparing with a generic converter control methodology.