• 제목/요약/키워드: Sliding speed

검색결과 701건 처리시간 0.027초

비전도 반평판 사이에서 미끄럼 운동하는 평판 층의 열탄성 불안정성 (Thermoelastic Instability of the Layer Sliding between Two Non-conducting Half-planes)

  • 하태원;조용구;김흥섭;이정윤;오재응
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.483-488
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    • 2003
  • Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness ${\alpha}$ slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properly simple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness ${\alpha}$ reduces, the system becomes more apt to thermoelastic instability. Moreover, the evolution of the system beyond the critical conditions has shown that even if low frequency perturbations are associated with low critical speed, it might be less critical than high frequency perturbations if the working sliding speed is much larger than the actual critical speed of the system.

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로봇 매니퓰레이터를 위한 신경회로망을 이용한 간편 슬라이딩 모드 제어 (Sliding Mode Control using Neural Network for a Robot Manipulator)

  • 박윤명;박양수;최부귀
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.355-355
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    • 2000
  • The position control accuracy of a robot manipulator is significantly deteriorated when a long arm robot is operated at a high speed. This paper presents a very simple sliding mode control which eliminates multiple mode residual vibration in a 개bot manipulator. The neural network is used to avoid that sliding mode condition is deviated due to the change of system parameter and disturbance. This paper is suggested control system which designed by sliding mode controller using neural network. The effectiveness of proposed scheme is demonstrated through computer simulation.

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영구자석 동기전동기의 강인 비선형 속도제어기의 설계 및 DSP에 기반한 구현 (Design and DSP-based Implementation of Robust Nonlinear Speed Control of Permanent Magnet Synchronous Motor)

  • 백인철;김경화;윤명중
    • 전력전자학회논문지
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    • 제4권1호
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    • pp.1-12
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    • 1999
  • 파라미터 변동이나 외란에 강인한 영구자석 동기전동기의 궤환선형화 속도제어기를 설계하고 DSP를 이용하여 실험 시스템을 구현하였다. 시스템의 상태변수에 비하여 매우 느리게 변화하는 파라미터의 추정을 위하여 MRAS를 이용한 추정방법이 MIT rule을 이용하여 유도되었다. 외란이나 시스템의 상태변수 정도의 변화를 보이는 피라미터에 대하여는 그영향이 고려된 준-선형화 비간섭 모델이 유도되었다. 이 모델을 이용하여 제어시스템의 강인성을 얻고자 경계층을 가지는 Sliding mode 제어기를 설계하고 PD 제어기를 적용한 기존의 제어기와 비교하였다. 제안된 제어 방법의 유용성은 Simulation과 DSP에 기반한 실험 시스템을 통하여 검증하였다.

′YAG 레이저에 의한 표면경화강의 레이저 경화와 마멸특성 (Laser hardening and Wear Characteristics of Surfaces hardening steel by YAG LASER)

  • 옥철호;서영백;조연상;배효준;박흥식;전태옥
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1999년도 제30회 추계학술대회
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    • pp.63-70
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    • 1999
  • Surface hardening of plain carbon steel (SM45C) by Laser are usually much finer and stronger than those of the base metals. The present study was under taken to investigate the wear resistance and a processing parameters such as, power density, pulse width, defocusing distance, and molten depth for surface modification of plain carbon steel. The wear test was carried out under experimental condition using the wear test device, and in which the annular surfaces of wear test specimens as well as mating specimen of alumina ceramics($Al_2O_3$) was rubbed in dry sliding condition. It is shown that molten depth and width depend on defocusing distance. The wear loss on variation of sliding speed was much in lower speed range below 0.2m/sec and in higher speed range above 0.7m/sec, but wear loss was little in intermediate speed range. It depends on oxidation speed and wear speed.

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유압식 인버터 제어기의 속도제어를 위한 퍼지기반 하이브리드 슬라이딩모드 제어기 설계 (Fuzzy-based Hybrid Fuzzy-Sliding Mode Controller for the Speed Control of a Hydraulic Inverter Controller)

  • 한권상;최병욱;안현식;김도현
    • 제어로봇시스템학회논문지
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    • 제9권3호
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    • pp.218-226
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    • 2003
  • Due to the friction characteristics of pump, cylinder packing and passenger car, in the elevation system actuated with hydraulic inverter, there exist dead zones. which cannot be controlled by a PID controller. To overcome the drawbacks, in this paper, we propose a new hybrid fuzzy-sliding mode control scheme, which controls the controller output between a sliding mode control output and a PID control output by fuzzy control method. The proposed hybrid control scheme achieves an improved control performance by using both controllers. We first propose a design method of the hybrid controller far a hydraulic system controlled by inverters, then propose a design method of a hybrid fuzzy-sliding mode centre] scheme. The effectiveness of the proposed control scheme is shown by simulation results, in which the proposed hybrid control method yields better control performance then the PID controlled scheme, not only in the zero-crossing speed region but also in the overall control region including steady-state region.

레이저 표면 딤플 패턴된 PMMA 소재 표면의 식염수 윤활 하에서의 미끄럼 마찰특성 (Sliding Friction Properties of Laser Surface Dimple Patterned on PMMA under Saline Lubricated)

  • 현동호;채영훈;정다이
    • Tribology and Lubricants
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    • 제39권4호
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    • pp.148-153
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    • 2023
  • Laser surface dimple patterning is a method of laser surface texturing to reduce lubrication sliding friction. The dimple pattern improves friction properties by reserving lubricant and trapping worn particles. This surface texturing technology can reduce coefficients of friction and extend the service life by applying a uniform load to the surface of the material. This study investigates the friction properties using PMMA, a highly compatible polymer material, as a specimen. We observe the friction properties of untextured specimens by processing specimens with dimple pattern densities of 5 and 10 on the surface area using laser. Dimple pattern density affects the coefficient of friction. We present the following friction property results using a pin-on-disc sliding friction test under saline lubrication. The coefficients of friction for the dimple patterned specimens are lower than those for the untextured specimens. As the normal load and sliding speed increase, the coefficients of friction of the dimple pattern specimens decrease differently from those of the untextured specimens. The specimen with a dimple pattern density of 5 at a normal load of 24.5 N and a sliding speed of 0.22 m/s has the best friction properties. Notably, different friction properties are exhibited depending on the dimple pattern densities.

미끄럼 마찰하에서의 베어링간의 마모 diagram과 마모기구 (Wear diagram and Wear Mechanisms of Bearing Steel in Frictional Sliding)

  • 임대순;박성길;조성재;방건웅;문한규
    • Tribology and Lubricants
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    • 제6권1호
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    • pp.108-115
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    • 1990
  • Wear diagrams, which are the three dimensional representations of the dependence of the wear rate on the applied pressure and the sliding speed, were constructed with the pin on ring type wear test results using 52100 wear couples. The pressure and speed ranges from 0.45 MPa to 45.30 MPa and from 0.012 m/sec to 0.12 (0.120)m/sec, respectively. The results show the mild to severe transition, which suggests the change of the wear mechanisms as a function of the pressure and sliding speed. The SEM micrographs of the corresponding worn area shows clearly that different wear mechanisms dominate.

고속/정밀 위치제어시스템의 모델인 및 제어에 관한 연구 (A Study on the Modeling and Control of High-Speed/High-Accuracy Position Control System)

  • 박민규;한창수
    • 제어로봇시스템학회논문지
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    • 제7권5호
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    • pp.399-406
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    • 2001
  • This paper presents a dynamic modeling and a sliding mode controller for the high-speed/high-accuracy position control system. The selected target system is the wire bonder assembly which is used in the semiconductor assembly process. This system is a reciprocating one around the pivot point that consists of VCM(voice coil motor) as an actuator and transducer horn as a bonding tool. For the modeling elements, the sys-tem is divided into electrical circuit, magnetic circuit and mechanical system. Each system is modeled using the bond graph method and united into the full system. Two major aims are considered in the design of the controller. The first one is that the horn must track the given reference trajectory. The second one is that the controller must be realizable by using the DSP board. Computer simulation and experimental results show that the designed sliding mode controller provides better performance than the PID controller.

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슬라이딩 모드 관측기를 이용한 영구자석 동기전동기 위치 및 속도 센서리스 제어 (The Speed and Position Sensorless Control of PMSM using the Sliding Mode Observer)

  • 한윤석;최정수;김영석
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 하계학술대회 논문집 F
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    • pp.2540-2542
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    • 1999
  • This paper presents a new speed and position sensorless control method of permanent magnet synchronous motors based on the sliding mode observer. The sliding mode observer structure and its design method are described. Also, Lyapunov functions are chosen for determining the adaptive law for the speed and the stator resistance estimator. The effectiveness of the proposed observer is confirmed by the experimental results.

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급속응고법으로 제조한 과공정 Al-Si합금분말 압출재의 마멸특성 (Wear Characteristics of the Extruded Bars of Hypereutectic Al-Si Alloy Powders produced by Rapid Solidification Process)

  • 안영남;조규섭;나형용
    • 한국주조공학회지
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    • 제14권5호
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    • pp.447-454
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    • 1994
  • Wear resistance and wear mechanism of hypereutectic Al-($15{\sim}40$)wt%Si alloys were investigated. Primary Si particles under $20{\mu}m$ size were formed in hypereutectic Al-Si alloy powders due to rapid solidification. But the Si particles of extruded bars were finely distributed in smaller size than that of atomized powders. The wear mechanism of hypereutectic Al-Si alloys was divided into three types of wear phenomena, which were abrasive wear, delamination wear and severe adhesive wear according to sliding speed and load. At low sliding speed and load, wear mechanism was abrasive wear, so Al-15wt%Si alloy showed the best wear resistance. At high sliding speed and load, wear mechanism was adhesive wear, and Al-40wt%Si alloy showed the best wear resistance.

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