• Title, Summary, Keyword: Slip Angle

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TECHNIQUE OF SEPARATE MEASURING SIDE SLIP FOR TOE ANGLE AND CAMBER ANGLE

  • Nozaki, H.
    • International Journal of Automotive Technology
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    • v.7 no.6
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    • pp.681-686
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    • 2006
  • The current flat type side slip tester measures only the total side slip. Therefore, measurement techniques which can be used to determine the side slip for each alignment element were examined. Because the side slip related to the camber angle varies depending on the unit load per travel wheel while the side slip related to the toe angle does not on the unit per travel wheel, but depends only on the direction of the tire, the side slip for each alignment element can be determined separately.

Autonomous Vehicle Driving Control Considering Tire Slip and Steering Actuator Performance (타이어 슬립과 조향작동장치의 성능을 고려한 무인자동차 자율주행 제어)

  • Park, C.H.;Gwak, G.S.;Jeong, H.U.;Hong, D.U.;Hwang, S.H.
    • Journal of Drive and Control
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    • v.12 no.3
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    • pp.36-43
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    • 2015
  • An autonomous vehicle control algorithm based on Ackerman Geometry is known to be reliable in low tire slip situation. However, vehicles at high speed make lateral errors due to high tire slip. In this paper, considering the tire slip of vehicles, the steering angle is determined based on the Ackerman Geometry and is supplemented tire slip angle by the Stanley steering algorithm. In addition, to prevent the tire slip, the algorithm, which restricts steering if a certain level of slip occurs, is used to reduce the lateral error. While many studies have been extended to include vehicle slip, studies also need to be carried out on the tire slip depending on hardware performance. The control algorithm of autonomous vehicles is compensated considering the sensor noise and the performance of steering actuator. Through the various simulations, it was found that the performance of steering actuator was the key factor affecting the performance of autonomous driving. Also, it was verified that the usefulness of steering algorithm considering the tire slip and performance of steering actuator.

Optimal Wheel Slip Control for Vehicle Stability During Cornering (선회시 차량의 주행 안정성을 위한 최적의 구동차륜 슬립제어)

  • 박종현;김찬영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.4
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    • pp.190-198
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    • 1997
  • Traction control systems are used to prevent the wheel slippage and to maximize the traction force. A new scheme of controlling the wheel slip during cornering by varying the slip ration as a function of the slip angle is proposed and dynamically simulated with the model of a front wheel driven passenger vehicle. Simulation results show that the proposed scheme is superior to conventional ones based on the fixed slip ratio during cornering and lane changes.

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Side Slip Angle Based Control Threshold of Vehicle Stability Control System

  • Chung Taeyoung;Yi Kyongsu
    • Journal of Mechanical Science and Technology
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    • v.19 no.4
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    • pp.985-992
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    • 2005
  • Vehicle Stability Control (VSC) system prevents vehicle from spinning or drifting out mainly by braking intervention. Although a control threshold of conventional VSC is designed by vehicle characteristics and centered on average drivers, it can be a redundancy to expert drivers in critical driving conditions. In this study, a manual adaptation of VSC is investigated by changing the control threshold. A control threshold can be determined by phase plane analysis of side slip angle and angular velocity which is established with various vehicle speeds and steering angles. Since vehicle side slip angle is impossible to be obtained by commercially available sensors, a side slip angle is designed and evaluated with test results. By using the estimated value, phase plane analysis is applied to determine control threshold. To evaluate an effect of control threshold, we applied a 23-DOF vehicle nonlinear model with a vehicle planar motion model based sliding controller. Controller gains are tuned as the control threshold changed. A VSC with various control thresholds makes VSC more flexible with respect to individual driver characteristics.

Analysis on the Shift Characteristics of Semi-Spherical CVT using 2-dimensional Friction Model (2차원 마찰모델을 이용한 구면무단변속기의 변속특성해석)

  • Kong, Jin-Hyung;Lim, Won-Sik;Park, Yeon-Gil;Kim, Jung-Yun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.4
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    • pp.103-109
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    • 2008
  • Semi-spherical CVT(SS-CVT) is one of friction drives, which transmits power via the friction force between a spherical shaped variator and output disks. The variator varies the speed ratio of SS-CVT continuously as well as transmits input power into the output shaft. Therefore two friction forces are normally applied on the variator; one is the longitudinal friction force for power transmission and the other is the lateral for shifting. In order to investigate the dynamic behavior of SS-CVT, we introduced a numerical model of 2-dimensional friction force using a function of slip ratio and slip angle. And a dynamic model, which describes the shifting mechanism of SS-CVT, is developed through 3-dimensional vector analysis. Finally we presented numerical results of the shift characteristics focused on the transient behavior of the variator's slip ratio and slip angle. The numerical results also show the typical CVT shifting characteristics of SS-CVT and stable shifting behaviors of the variator.

Study on Earth Pressure Acting Against Caisson Structure with the Heel (뒷굽이 있는 케이슨 안벽에 작용하는 토압에 대한 연구)

  • Yoo, Kun-Sun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.2
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    • pp.67-76
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    • 2017
  • In this study, the effect of caisson heel on the active earth pressure is investigated. Using limit analysis method, inclinations of slip surface developed above the heel with different lengths are analyzed. The shorter the heel length, the larger those of inside slip surface, however those of outside slip surface are not changed. According to the relative heel length, relationships of internal friction angle of backfill material - wall friction angle between caisson structure and backfill - friction angle acting on virtual section at the end of heel are presented. Earth pressures acting against caisson structure with relatively short heel are smaller than Rankine earth pressure but always greater than Coulomb earth pressure which does not consider the heel length.

Strain Gradient Crystal Plasticity Finite Element Modeling for the Compression Behaviors of Single Crystals (단결정 압축 변형 거동의 변형구배 결정소성 유한요소해석)

  • Jung, Jae-Ho;Cho, Kyung-Mox;Choi, Yoon Suk
    • Korean Journal of Materials Research
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    • v.27 no.12
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    • pp.679-687
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    • 2017
  • A strain-gradient crystal plasticity finite element method(SGCP-FEM) was utilized to simulate the compressive deformation behaviors of single-slip, (111)[$10{\bar{1}}$], oriented FCC single-crystal micro-pillars with two different slip-plane inclination angles, $36.3^{\circ}$ and $48.7^{\circ}$, and the simulation results were compared with those from conventional crystal plasticity finite element method(CP-FEM) simulations. For the low slip-plane inclination angle, a macroscopic diagonal shear band formed along the primary slip direction in both the CP- and SGCP-FEM simulations. However, this shear deformation was limited in the SGCP-FEM, mainly due to the increased slip resistance caused by local strain gradients, which also resulted in strain hardening in the simulated flow curves. The development of a secondly active slip system was altered in the SGCP-FEM, compared to the CP-FEM, for the low slip-plane inclination angle. The shear deformation controlled by the SGCP-FEM reduced the overall crystal rotation of the micro-pillar and limited the evolution of the primary slip system, even at 10 % compression.

A Study on Integrated Control of AFS and ARS Using Fuzzy Logic Control Method (Fuzzy Logic 제어를 이용한 AFS와 ARS의 통합제어에 관한 연구)

  • Song, Jeonghoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.65-70
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    • 2014
  • An Integrated Dynamics Control system with four wheel Steering (IDCS) is proposed and analysed in this study. It integrates and controls steer angle of front and rear wheel simultaneously to enhance lateral stability and steerability. An active front steer (AFS) system and an active rear steer (ARS) system are also developed to compare their performances. The systems are evaluated during brake maneuver and several road conditions are used to test the performances. The results showed that IDCS vehicle follows the reference yaw rate and reduces side slip angle very well. AFS and ARS vehicles track the reference yaw rate but they can not reduce side slip angle. On split-${\mu}$ road, IDCS controller forces the vehicle to go straight ahead but AFS and ARS vehicles show lateral deviation from centerline.

Roles of Bearing Angle in Bond Action of Reinforcing Bars to Concrete

  • Choi OanChul
    • Journal of the Korea Concrete Institute
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    • v.16 no.5
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    • pp.719-724
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    • 2004
  • The ribs of deformed bars can split the cover concrete by wedging action or shear off the concrete in front of the ribs. As slip of deformed bars increases, the rib face angle is flattened by the crushed concrete wedge, which reduces the rib face angle to a smaller bearing angle. The roles of bearing angle are explored to simulate this observation. Analytical expressions to determine bond strength for splitting and pullout failure are derived, where the bearing angle is a key variable. As the bearing angle is reduced, splitting strength decreases and shearing strength increases. When splitting strength becomes larger than shearing strength, the concrete key is supposed to be sheared off and the bearing angle is reduced with decreasing the splitting strength. As bars slip, bearing angle decreases continually so that splitting bond strength is maintained to be less than shearing bond strength. The bearing angle is found to play a key role in controlling the bond failure and determination of bond strength of ribbed reinforcing steel in concrete structures.

A New Method Calculating Total Slip of Fault with Fault Separation (단층변위를 이용한 단층의 총 이동량 계산법)

  • Hwang, Jae Ha
    • Economic and Environmental Geology
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    • v.31 no.6
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    • pp.547-555
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    • 1998
  • A new trigonometrical method for calculating total slip (T) of faulting is presented. The parameters for the calculations are used rake of fault striation, strike and dip of fault and of index planar structure such as bedding plane. The faults are groupped into three types. The direction of plunging of fault striation is out of a range ${\pm}90^{\circ}$ to the bedding dip direction in $360^{\circ}$ system, which is groupped into the type I. Meanwhile, the case of the direction lies in the above range can be separated into two different types, type II and type III, according to relative largeness of the angles rake of fault striation and i (see text). The type II has smaller rake than angle i and the type III has larger rake than angle i. Here I propose a few equations for calculating not only total slip (T) but strike slip (L) or dip slip (S) of the faulting. The equations are adapted selectively to the types of fault mentioned before. The limitation of the method is that the equations do not fit to polyphase faulting.

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