• Title/Summary/Keyword: wheel tracking

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Determination of Proper Loading Speed for Deformation Strength Test of Asphalt Concretes (아스팔트 콘크리트 변형강도 시험에서의 적정 하중재하속도 선정 연구)

  • Cho, Byung-J.;Park, Tae-W.;Doh, Young-S.;Kim, Kwang-W.
    • International Journal of Highway Engineering
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    • v.10 no.4
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    • pp.225-234
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    • 2008
  • This study was carried out to select proper loading speed for deformation strength ($S_D$) of asphalt mixtures. Kim test using loading head of diameter(40mm) with radius(10mm) was conducted to measure $S_D$ in different loading speed (10mm/min, 30mm/min, 50mm/min, 70mm/min) and wheel tracking test was also conducted. The regression analyses between the So values and WT results were carried out by loading speeds. Higher $S_D$ was observed as increasing loading speed. This means that loading speed is a high influencing factor on $S_D$. The loading speed of 30mm/min was found as an optimum for better correlation with WT results than any other speeds from the regression analysis between $S_D$ and wheel tracking test results. $S_D$ value measured at other loading speed than 30mm/min has to apply the conversion coefficients.

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Orbit Determination Accuracy Improvement for Geostationary Satellite with Single Station Antenna Tracking Data

  • Hwang, Yoo-La;Lee, Byoung-Sun;Kim, Hae-Yeon;Kim, Hae-Dong;Kim, Jae-Hoon
    • ETRI Journal
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    • v.30 no.6
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    • pp.774-782
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    • 2008
  • An operational orbit determination (OD) and prediction system for the geostationary Communication, Ocean, and Meteorological Satellite (COMS) mission requires accurate satellite positioning knowledge to accomplish image navigation registration on the ground. Ranging and tracking data from a single ground station is used for COMS OD in normal operation. However, the orbital longitude of the COMS is so close to that of satellite tracking sites that geometric singularity affects observability. A method to solve the azimuth bias of a single station in singularity is to periodically apply an estimated azimuth bias using the ranging and tracking data of two stations. Velocity increments of a wheel off-loading maneuver which is performed twice a day are fixed by planned values without considering maneuver efficiency during OD. Using only single-station data with the correction of the azimuth bias, OD can achieve three-sigma position accuracy on the order of 1.5 km root-sum-square.

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Development of Path Tracking Algorithm and Variable Look Ahead Distance Algorithm to Improve the Path-Following Performance of Autonomous Tracked Platform for Agriculture (농업용 무한궤도형 자율주행 플랫폼의 경로 추종 및 추종 성능 향상을 위한 가변형 전방 주시거리 알고리즘 개발)

  • Lee, Kyuho;Kim, Bongsang;Choi, Hyohyuk;Moon, Heechang
    • The Journal of Korea Robotics Society
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    • v.17 no.2
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    • pp.142-151
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    • 2022
  • With the advent of the 4th industrial revolution, autonomous driving technology is being commercialized in various industries. However, research on autonomous driving so far has focused on platforms with wheel-type platform. Research on a tracked platform is at a relatively inadequate step. Since the tracked platform has a different driving and steering method from the wheel-type platform, the existing research cannot be applied as it is. Therefore, a path-tracking algorithm suitable for a tracked platform is required. In this paper, we studied a path-tracking algorithm for a tracked platform based on a GPS sensor. The existing Pure Pursuit algorithm was applied in consideration of the characteristics of the tracked platform. And to compensate for "Cutting Corner", which is a disadvantage of the existing Pure Pursuit algorithm, an algorithm that changes the LAD according to the curvature of the path was developed. In the existing pure pursuit algorithm that used a tracked platform to drive a path including a right-angle turn, the RMS path error in the straight section was 0.1034 m and the RMS error in the turning section was measured to be 0.2787 m. On the other hand, in the variable LAD algorithm, the RMS path error in the straight section was 0.0987 m, and the RMS path error in the turning section was measured to be 0.1396 m. In the turning section, the RMS path error was reduced by 48.8971%. The validity of the algorithm was verified by measuring the path error by tracking the path using a tracked robot platform.

A Model Reference Variable Structure Control based on a Neural Network System Identification for an Active Four Wheel Steering System

  • Kim, Hoyong;Park, Yong-Kuk;Lee, Jae-Kon;Lee, Dong-Ryul;Kim, Gi-Dae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.6
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    • pp.142-155
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    • 2000
  • A MIMO model reference control scheme incorporating the variable structure theory for a vehicle four wheel steering system(4WS) is proposed and evaluated for a class of continuous-time nonlinear dynamics with known or unknown uncertainties. The scheme employs an neural network to identify the plant systems, where the neural network estimates the nonlinear dynamics of the plant. By the Lyapunov direct method, the algorithm is proven to be globally stable, with tracking errors converging to the neighborhood of zero. The merits of this scheme is that the global system stability is guaranteed and it is not necessary to know the exact structure of the system. With the resulting identification model which contains the neural networks, it does not need higher degrees of freedom vehicle model than 3 degree of freedom model. Th proposed scheme is applied to the active four wheel system and shows the validity is used to investigate vehicle handing performances. In simulation of the J-turn maneuver, the reduction of yaw rate overshoot of a typical mid-size car improved by 30% compared to a two wheel steering system(2WS) case, resulting that the proposed scheme gives faster yaw rate response and smaller side angle than the 2WS case.

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인공위성 반작용휠의 미소진동 측정 및 분석

  • Oh, Shi-Hwan;Rhee, Seung-Wu
    • Aerospace Engineering and Technology
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    • v.3 no.2
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    • pp.25-33
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    • 2004
  • In this paper, we briefly introduce the micro-vibration test bench of KARI and the test and analysis method of RWA(Reaction Wheel Assembly) micro-vibration. The micro-vibration of RWA is measured on a KISTLER dynamic plate which can measure the time signal of 6 DOF simultaneously up to 400Hz. Measured data are extensively evaluated with respect to the wheel spin rate to identify the complicate wheel dynamic characteristics, and the static/dynamic unbalances are estimated from the extracted first harmonic component as a part of evaluation process. The estimated static and dynamic unbalances. 0.79gcm and 17.4gcm² respectively. The structural resonance mode and two rocking modes observed as a results of its frequency analysis. Several higher order harmonic components observed, which come from its rotor shape as well as the wheel bearing characteristics.

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A Study for Path Tracking of Vehicle Robot Using Ultrasonic Positioning System (초음파 위치 센서를 이용한 차량 로봇의 경로 추종에 관한 연구)

  • Yoon, Suk-Min;Yeu, Tae-Kyeong;Park, Soung-Jea;Hong, Sup;Kim, Sang-Bong
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.795-800
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    • 2008
  • The paper presents research for the established experiment environment of multi vehicle robot, localization algorithm that is based on vehicle control, and path tracking. The established experiment environment consists of ultrasonic positioning system, vehicle robot, server and wireless module. Ultrasonic positioning system measures positioning for using ultrasonic sensor and generates many errors because of the influence of environment such as a reflection of wall. For a solution of this fact, localization algorithm is proposed to determine a location using vehicle kinematics and selection of a reliable location data. And path tracking algorithm is proposed to apply localization algorithm and LOS, finally, that algorithms are verified via simulation and experimental

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Development of Travelling Control Algorithm Based Fuzzy Perception and Neural Network for Two Wheel Driving Robot (퍼지추론 및 뉴럴네트워크 기반 2휠구동 로봇의 주행제어알고리즘 개발)

  • Kang, Eon-Uck;Yang, Jun-Seok;Cha, Bo-Nam;Park, In-Soo
    • Journal of the Korean Society of Industry Convergence
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    • v.17 no.2
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    • pp.69-76
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    • 2014
  • This paper proposes a new approach to the design of cruise control system of a mobile robot with two drive wheel. The proposed control scheme uses a Gaussian function as a unit function in the fuzzy neural network, and back propagation algorithm to train the fuzzy neural network controller in the framework of the specialized learning architecture. It is proposed a learning controller consisting of two neural network-fuzzy based on independent reasoning and a connection net with fixed weights to simply the neural networks-fuzzy. The performance of the proposed controller is shown by performing the computer simulation for trajectory tracking of the speed and azimuth of a mobile robot driven by two independent wheels.

Omni-Directional Magnet Wheel using Magnetic Shield (자기 차폐를 이용한 전방향 자기차륜)

  • Shim, Ki-Bon;Lee, Sang-Heon;Jung, Kwang-Suk
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.9
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    • pp.72-80
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    • 2009
  • When the magnet wheel rotates over a conducting plate, it generates the traction torque as well as the repulsive force on the conducting plate. Partially-cut traction torque results in the linear force into the tangential direction. To cut the traction torque, the concept of magnetic shield is introduced. The direction change of the linear force is realized varying the shielded area of magnetic field. That is, the tangential direction of non-shielded open area becomes the direction of the linear thrust force. Specially a shape of permanent magnets composing the magnet wheel leads to various pattern of magnetic forces. So, to enlarge the resulting force density and compensate its servo property a few simulations are performed under various conditions such as repeated pattern, pole number, radial width of permanent magnets, including shape of open area. The theoretical model of the magnet wheel is derived using air-gap field analysis of linear induction motor, compared with test result and the sensitivity analysis for its parameter change is performed using common tool; MAXWELL. Using two-axial wheel set-up, the tracking motion is tested for a copper plate with its normal motion constrained and its result is given. In conclusion, it is estimated that the magnet wheel using partial shield can be applied to a noncontact conveyance of the conducting plate.

Motion Control of Two Welding Mobile Robot with Seam Tracking Sensor

  • Byuong-Oh;Jeon, Yang-Bae;Suh, Jin-Ho;Oh, Myung-Suk;Kim, Sang-bong
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.2
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    • pp.30-38
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    • 2003
  • This paper proposed PID controller for torch slider and PD controller for motor right wheel. to control the motion of two-wheeled welding mobile robot with seam tracking sensor touched on welding line. The motion control is realized in the view of keeping constant welding velocity and precise seam tracking even though the target welding line is on straight line or curved line. The position and direction of the body of the mottle robot are controlled by using signal errors between seam tracking sensor and body positioning sensor attached on the end of torch slider and body side of the mobile robot, respectively. In turning motion, the body and the torch slider are controlled by using the kinematic model related with two motions of body turning and torch sliding. The straight locomotion is controlled according to eleven control patterns obtained from displacements between two sensors of the seam tracking sensor and the body positioning sensor. The effectiveness is proven through the experimental results fur lattice type welding line. Through the experimental results, we can see that the position value of the electrode end point and the welding velocity are controlled almost constantly both in straight and turning locomotion.

Tracking Resistance of Epoxy Mold Insulating Materials by the Rotating Wheel Dip Test (회전윤법에 의한 에폭시 몰드 절연재료의 내트래킹성 평가)

  • Cho, Han-Goo;Yun, Mun-Su;Park, Yang-Kwan
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1590-1592
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    • 2000
  • The time to tracking breakdown of treated filled specimen is longer than untreated filled specimen. And, after the RWDT, the surface of specimen by adding untreated filler appeared heavy erosion. It was found that the addition to surface treated filler. the better tracking resistance. In the RWDT, the breakdown specimen is not affected by the dry flashover voltage. despite the fact that the surface degradation of tracking test has different state on each specimen. This suggests that wet flashover voltage play an important role in evaluating of tracking and erosion on the surface degradation in tracking test. And, the flashover voltage of specimen under wet conditions are greatly affected by the salt concentration and degree of degradation by the RWDT. Because of hydrophobicity and degree of degradation by the RWDT, the flashover voltage of treated filled specimen is higher than that of untreated filled specimen. Different types of specimen may have different hydrophobicity and their surface state under contaminated conditions may not be the same. It is assumed that this phenomenon is related to the decrease in hydrophobicity of the surface of the materials.

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