• Title, Summary, Keyword: Loop Wheel

Search Result 78, Processing Time 0.028 seconds

An Evaluation on the Steering Stability of the Guideway Vehicle (안내궤도 차량의 조향 안정성 평가)

  • 윤성호
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.10 no.1
    • /
    • pp.209-215
    • /
    • 2002
  • A study of the guideway vehicle was made for a comparison of ride stabilities between its two primary steering types; one is the front wheel steering and the other the front-rear wheel. A numerical model as a closed loop system was built for an investigation of various factors to have an influence on the vehicular critical speed which is closely associated with ridabilities. It was shown that dynamics stabilities of the front steering type was much better over a large value of steering gain and the longer distance between front axle and guide link for both types provided better stabilities as well. A large steering gain ratio of the front to the rear significantly plays an important role in an improvement of stability in the front-rear steering. To observe a qualitative trend on stability behaviors, the root locus was obtained by considering a time lag which may be frequently caused by the complicated steering mechanism. In performing so, the appropriate selection of steering gain had a greater effect on the front-rear steering vehicle far more ride comfort. In addition, the dynamics model proposed here can be utilized for a more accurate evaluation on the vehicle design in lateral or yawing absorber and moreover expanded for the analysis of independent four-wheel steering vehicle.

A study on the 3-axis attitude stabilization of Koreasat (무궁화 방송통신 위성의 3축 자세 안정화 장치에 관한 연구)

  • 진익민;백명진;김진철
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.793-798
    • /
    • 1993
  • In this study the attitude control of the KOREASAT is investigated. The KOREASAT is a geostationary satellite and its 3 attitude angles, namely, roll, pitch and yaw angles, are stabilized by using the 3-axis stabilization technique. In the pitch control loop, the pitch attitude angle received from the earth sensor is processed in the attitude processing electronics by using PI type control logic, and the control command is sent to the momentum wheel assembly to generate the control torque by varying the wheel rate. The roll/yaw attitude control is performed by activating a magnetic torquer or by firing appropriate thrusters. The magnetic torquer interacts with the earth magnetic field to produce the control torque, and the thrusters are used to control the larger roll attitude errors. In this study dynamic modelling of the satellite is performed. And the earth sensor, the momentum wheel, and the magnetic torquer are mathematically modelled. The 3-axis attitude control logic is implemented to make the closed-loop system and simulations are carried out to verify the implemented control laws.

  • PDF

Fatigue Characteristics of Precast Concrete Bridge Decks under Wheel Load Condition (윤하중조건에서의 프리캐스트 콘크리트 바닥판 피로특성)

  • Joo, Bong-Chul;Park, Hung-Seok;Kim, Young-Jin;Song, Jae-Joon
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.394-397
    • /
    • 2006
  • For checking fatigue safety and endurance of precast concrete deck and loop joint system in the steel plate girder composite bridge, the test composite bridge model was made for the fatigue experiment by the wheel load machine. The fatigue tests of 1,000,000 cycles were implemented according to wheel load condition of DB24 rear axle of Korea Highway Design Code. From the test results, the loop joint system for the precast deck has a sufficient flexural capacity. Although a little lower longitudinal continuity capacity is evaluated than general sound cast-in-place RC bridge deck, there is no problem about the safety. The overall fatigue level of safety defined by the code is satisfied.

  • PDF

Flexible Loop Wheel Mechanism for Intestine Movement (탄성 루프형 바퀴를 이용한 장 내 이동 메커니즘)

  • Im, Hyeong-Jun;Min, Hyeon-Jin;Kim, Byeong-Gyu;Kim, Su-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.26 no.2
    • /
    • pp.314-321
    • /
    • 2002
  • An endoscope is usually inserted into the human body for the inspection of the gullet, stomach, and large intestine (colon) and this may cause discomfort to patients and damage to tissues during diagnostic or therapeutic procedures. This situation necessitates a self-propelling endoscope. There are many kinds of mechanism to move in a rigid pipe. However, these methods are difficult to apply directly to the endoscope. The main reason is that human intestine cannot be considered as a uniform, straight, and rigid pipe. This paper proposes a flexible loop wheel mechanism, which is adaptable to the human intestine. This mechanism is designed and fabricated by a simple modeling, and tested by an experiment. Finally, the actuator is inserted into the pig colon.

Structural and Thermal Sensitivity Analysis of a High-Precision Centerless Grinding Machine for Machining Ferrules (페룰 가공용 초정밀 무심 연삭기의 구조적 및 열적 민감도 해석)

  • Kim, Seok-Il;Lee, Won-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.30 no.12
    • /
    • pp.1634-1641
    • /
    • 2006
  • High-precision centerless grinding machines are emerging as a means of finishing the outer diameter grinding process required for ferrules, which are widely used as fiber optic connectors. In this study, a sensitivity analysis for structural and thermal characteristics was carried out using a virtual prototype of a centerless grinding machine to realize systematic design technology and performance improvements required to manufacture ferrules. The prototype consisted of a concrete-filled bed, hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW table feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The results of the structural sensitivity analysis illustrated that the vertical stiffness of hydrostatic guideway for the RW table feed system greatly influenced the horizontal loop stiffness, and the results of the thermal sensitivity analysis illustrated that the heat generation rates at hydrostatic bearings and belt pulley greatly influenced the temperature rise of hydrostatic bearings and the deviation of thermal displacement between GW and RW.

HILS(Hardware-In-the-Loop Simulation) Development of a Steering HILS System (전동식 동력 조향 장치 시험을 위한 HILS(Hardware-In-the-Loop Simulation) 시스템 개발)

  • 류제하;노기한;김종협;김희수
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.7 no.9
    • /
    • pp.105-111
    • /
    • 1999
  • The paper presents development of a Hardware-In-the-Loop simulation (HILS) system for the purpose of testing performance, stability, and reliability of an electronic power steering system(EPS). In order to realistically test an EPS by the proposed HILS apparatus, a simulated uniaxial dynamic rack force is applied physically to the EPS hardware by a pnumatic actuator. An EPS hardware is composed of steering wheel &column, a rack & pinion mechanism, andas motor-driven power steering system. A command signal for a pneumatic rack-force actuator is generated from the vehicle handling lumped parameter dynamic model 9software) that is simulated in real time by using a very fast digital signal processor. The inputs to the real-time vehicle dynamic simulation model are a constant vehicle forward speed and from wheel steering angles driven through a steering system by a driver. The output from a real-time simulation model is an electric signal that is proportional to the uniaxial rack force. The vehicle handling lumped parameter dynamic model is validated by a fully nonlinear constrained multibody vehicle dynamic model. The HILS system simulation results sow that the proposed HILS system may be used to realistically test the performance stability , and reliability of an electronic power steering system is a repeated way.

  • PDF

Mobile Robot Localization Using Optical Flow Sensors

  • Lee, Soo-Yong;Song, Jae-Bok
    • International Journal of Control, Automation, and Systems
    • /
    • v.2 no.4
    • /
    • pp.485-493
    • /
    • 2004
  • Open-loop position estimation methods are commonly used in mobile robot applications. Their strength lies in the speed and simplicity with which an estimated position is determined. However, these methods can lead to inaccurate or unreliable estimates. Two position estimation methods are developed in this paper, one using a single optical flow sensor and a second using two optical sensors. The first method can accurately estimate position under ideal conditions and also when wheel slip perpendicular to the axis of the wheel occurs. The second method can accurately estimate position even when wheel slip parallel to the axis of the wheel occurs. Location of the sensors is investigated in order to minimize errors caused by inaccurate sensor readings. Finally, a method is implemented and tested using a potential field based navigation scheme. Estimates of position were found to be as accurate as dead-reckoning in ideal conditions and much more accurate in cases where wheel slip occurs.

MAXIMUM BRAKING FORCE CONTROL UTILIZING THE ESTIMATED BRAKING FORCE

  • Hong, D.;Hwang, I.;SunWoo, M.;Huh, K.
    • International Journal of Automotive Technology
    • /
    • v.8 no.2
    • /
    • pp.211-217
    • /
    • 2007
  • The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS (Anti-lock Brake System) systems. In realizing the wheel slip control systems, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance and stability enhancement. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm is proposed for maximizing the braking force. An adaptive law is formulated to estimate the braking force in real-time. The wheel slip controller is designed based on the Lyapunov stability theory considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm searches for the optimal target slip value based on the estimated braking force. The performance of the proposed wheel slip control system is verified in HILS (Hardware-In-the-Loop Simulator) experiments and demonstrates the effectiveness of the wheel slip control in various road conditions.

In-process Truing of Metal-bonded Diamond Wheels for Electrolytic In-process Dressing (ELID) Grinding

  • Saleh, Tanveer;Biswas, Indraneel;Lim, Han-Seok;Rahman, Mustafizur
    • International Journal of Precision Engineering and Manufacturing
    • /
    • v.9 no.3
    • /
    • pp.3-6
    • /
    • 2008
  • Electrolytic in-process dressing (ELID) grinding is a new technique for achieving a nanoscale surface finish on hard and brittle materials such as optical glass and ceramics. This process applies an electrochemical dressing on the metal-bonded diamond wheels to ensure constant protrusion of sharp cutting grits throughout the grinding cycle. In conventional ELID grinding, a constant source of pulsed DC power is supplied to the ELID cell, but a feedback mechanism is necessary to control the dressing power and obtain better performance. In this study, we propose a new closed-loop wheel dressing technique for grinding wheel truing that addresses the efficient correction of eccentric wheel rotation and the nonuniformity in the grinding wheel profile. The technique relies on an iterative control algorithm for the ELID power supply. An inductive sensor is used to measure the wheel profile based on the gap between the sensor head and wheel edge, and this is used as the feedback signal to control the pulse width of the power supply. We discuss the detailed mathematical design of the control algorithm and provide simulation results that were confirmed experimentally.

Structural Characteristic Analysis of a High-Precision Centerless Grinding Machine with Concrete-Filled Bed (콘크리트 층진 베드를 적용한 초정밀 무심 연삭기의 구조 해석)

  • Kim Seok Il;Cho Jae Wan
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.22 no.2
    • /
    • pp.172-179
    • /
    • 2005
  • A high-precision centerless grinding machine has been recognized as a core equipment performing the finish outer-diameter grinding process of ferrules which are widely used as fiber optic connectors. In this study, in order to realize the high-precision centerless grinding machine, the structural characteristic analysis and evaluation are carried out on the virtual prototype consisted of the steel bed, hydrostatic GW and RW spindle systems, hydrostatic RW feed mechanism, RW swivel mechanism, and on-machine GW and RW dressers. The loop stiffnesses of centerless grinding machine are estimated based on the relative deformations between GW and RW caused by the grinding forces. And the simulated results illustrate that the concrete-filled bed has the considerable effect on the improvement of the structural stiffness of centerless grinding machine.