• Title/Summary/Keyword: skidding

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Mathematical Models Predicting for Tree Skidding Forces and Its Evaluations (집재견인력 예측을 위한 수학적 모델의 개발과 평가)

  • Oh, Jae-Heun;Hwang, Jin Sung;Cha, Du Song
    • Journal of Korean Society of Forest Science
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    • v.96 no.4
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    • pp.448-454
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    • 2007
  • Mathematical models for predicting the ground and semi-ground skidding force have been developed. The skidding force is expressed as a function of log geometry, total weight and coefficient of skidding. The coefficient of skidding was determined under field tests. The validity of the model developed was examined by comparing the predicted and measured skidding forces. Calculated ground skidding force, using the model developed can be predicted well with that measured experimentally. The semi-ground skidding force calculated from the model, however, does not predict well due to its confined conditions experimentally.

Relationships Between Pre-Skidding and Pre-Braking Speed (활주 직전과 제동 직전 속도의 상관관계 규명에 관한 연구)

  • Ryu, Tae-Seon;Jeon, Jin-U;Park, Hong-Han;Lee, Su-Beom
    • Journal of Korean Society of Transportation
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    • v.27 no.1
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    • pp.43-51
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    • 2009
  • This paper investigates the accuracy of vehicle pre-braking speed estimates based upon tire/roadway coefficient of friction (drag factor) measurements and skid mark measurements Data for pre-braking and pre-skidding speeds were collected to determine if there were any correlations between pre-braking speeds and pre-skidding speeds. Braking tests were performed on two vehicles using various measurement devices including a fifth wheel, a speed gun, and a vericom 2000. The vehicle speeds, braking distances, skid mark distances, and deceleration histories were recorded. From these data. coefficients of friction and vehicle pre-skidding speeds for the tested road surface were calculated. The pre-skidding speeds were then compared to the actual pre-braking speeds of the vehicles in order to establish relationships between pre-skidding and pre-braking speed. A correlation between the Pre-skidding speed and the actual pre-braking speed was established for the study data.

A Study on Tractive Resistance Prediction of Logging machine (집재기계의 견인저항예측에 관한 연구)

  • Oh, Jae Heun;Cha, Du Song
    • Journal of Forest and Environmental Science
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    • v.17 no.1
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    • pp.62-73
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    • 2001
  • This study was conducted to predict the tractive resistance for tree length logs being skidded by ground based logging machine. The mathematical models for predicting the tractive resistance of tree length log have been developed. The tractive resistance is expressed as a function of log weight, skidding coefficient, and ground gradient. The skidding coefficients for four species of Korean pine, Japanese larch, mongolian oak, and cork oak were determined under laboratory condition using universal testing machine and small soil bin, Three different tractive resistance models were applied to four species and compared with each other. The ratios (T/Wt) of skidding-line tensions to the skidding log weight increased linearly with increment in ground gradient. Semi-ground skidding generally required smaller tensions than ground skidding under given condition. Results of this study can be utilized as basic information for logging machine selection and power requirement of skidding winch.

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Adaptive Formation Control of Nonholonomic Multiple Mobile Robots Considering Unknown Slippage (미지의 미끄러짐을 고려한 비홀로노믹 다개체 이동 로봇의 적응 군집 제어)

  • Choi, Yoon-Ho;Yoo, Sung-Jin
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.1
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    • pp.5-11
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    • 2010
  • An adaptive formation control approach is proposed for nonhonolomic multiple mobile robots considering unknown slipping and skidding. It is assumed that unknown slipping and skidding effects are bounded by unknown constants. Under this assumption, the adaptive technique is employed to estimate the bounds of unknown slipping and skidding effects of each mobile robot. To deal with the skidding effect included in kinematics, the dynamic surface design approach is applied to design a local controller for each mobile robot. Using Lyapunov stability theorem, the adaptation laws for tuning bounds of slipping and skidding are induced and it is proved that all signals of the closed-loop system are bounded and the tracking errors and the synchronization errors of the path parameters converge to an adjustable neighborhood of the origin. Finally, simulation results are provided to verify the effectiveness of the proposed approach.

Polar Converting Logic of Bank-To-Turn with Skidding for Small Size UAV (소형무인기의 Skidding을 포함하는 Bank-To-Turn 하중 배수 분배 논리)

  • Kyungjae Nam
    • Journal of the Korea Institute of Military Science and Technology
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    • v.27 no.4
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    • pp.485-494
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    • 2024
  • In this paper, polar converting logic of bank-to-turn with skidding is provided for small size UAV. In general, original polar converting logic has problems of singularity, safety and flight data analysis when acceleration commands diverge at the end of terminal guidance. To solve those problems, new methodology of polar converting logic of bank-to-turn with skidding is presented. It can easily solve singularity problem, increase safety and provide intuition of data analysis. Simulation and flight results are presented to verify proposed polar converting logic for bank-to-turn with skidding method.

A Study on Ground Vehicle Mechanics for Steep Slope Forest Operations - Rubber-Tired Log Skidding Tractor Operations - (급경사지 산림작업을 위한 차량의 역학분석에 관한 연구 -차륜형 집재작업 트랙터를 중심으로-)

  • Chung, Joo Sang;Chung, Woo Dam
    • Journal of Korean Society of Forest Science
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    • v.84 no.2
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    • pp.218-225
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    • 1995
  • In this paper, a mechanical analysis model for steep-slope log-skidding operations of a rubber-tired tractor is discussed and the applicability of the model is investigated. The model largely consists of mathematical analysis models for log drag, dynamic vehicle weight distributions and soil-vehicle traction. For the case study, a theoretical data set for log skidding operations is used in investigating the effect of the factors influencing the results of mechanical analysis or the productivity of skidding operations. The analyses include 1) the effect of log choking methods on tangential log-skidding force, 2) the effects of the change in travel speed and log load on the required input power to the wheels and 3) the log skidding performance of a two-wheel drive compared with that of a four-wheel drive.

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Comparison of a Point-Grid-Method and a Buffering-Method to Calculate Skidding Distance for Timber Harvest Planning (목재수확계획을 위한 집재거리 계산방법중 포인트그리드방법과 버퍼링방법의 비교분석)

  • Park, Soo-Kyoo;Kang, Gun-Uh
    • Journal of Korean Society of Forest Science
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    • v.97 no.6
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    • pp.611-616
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    • 2008
  • The investigation was accomplished on the test area in Forest Practice Research Center in order to compare Point Grid method with Bufferring method in process of the calculation of the Actual Mean Skidding Distance with the GIS aided harvesting method. the investigation site amounted to 264.9 ha in area and 32.67 m in the road density, 306.1 m in road spacing. the Net Correction Factor (Kn) was 1.53 in both sides skidding. the theoretical mean skidding distance was 72.52 m. the shortest mean skidding distance amounted to 149.57 m with point grid method and 139.68 m with Buffering methode. skidding distance correction factor (Kr) was 2.15. actual mean skidding distance amounted to 251.51 m and factor of wood assortment skidding (Kg) was 3.29. when the tractor (Dongyang) and tower yader (Koller 303) are used on investigation site, the logging cost is calculated 11,808 Won with Tractor below 25% slope and 12,336 won with Tractor between 25~55% slope, 10,020 won with Tower Yarder more than 55% slope.

Improvement of Pavement Skid Resistance (노면 미끄럼저항 증진방앙 연구)

  • 임승욱;유태석;엄주용
    • Proceedings of the Korea Concrete Institute Conference
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    • 1996.04a
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    • pp.216-224
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    • 1996
  • Recently, Korea Highway Corporation has attemped to improve the highway safety in accordance with minimizing user's imconveniences. Currently, the Anti Skidding Pavement(ASP) has been introduced as a safety countermeasure on the safety frailty sections. In this study, a series of field evaluations on pavement skid resistance have been conducted on the skid frailty sections to analyze the effects and problems of the Anti Skidding Pavement (ASP), and to understand the behavior of pavement skid resistance due to pavement type, section characteristics, vehicles' speed and traffec volume. Test results show the Anti Skidding Pavement (ASP) has the effects to induce vehicles' speed reduction. However, there are no effects to increase skid resistance. According to these results, it is demanded to improve the applying method of current Anti Skidding Pavement (ASP) to devise an effective safety countermeasure for pavement skid, and to increase pavement skid resistance.

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A Study on Robust Trajectory Tracking Control of a Skid Steering Robots (미끄럼 조향 로봇의 강인한 궤적 추종 제어에 관한 연구)

  • Baek, Woon-Bo;Kim, Won-Ho
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.1
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    • pp.121-127
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    • 2010
  • We consider the robust trajectory tracking control problem for a skid steering mobile robots. A dynamic model is derived accounting for the effects of wheel skidding. The control design utilizes the dynamic feedback linearization techniques, so as to obtain a predictable behavior for the instantaneous center of rotation thus preventing excessive skidding. The additive controller using the sliding mode type is then robustified against the unmodelled dynamics and parameter uncertainty. Simulation results show the good performances under excessively uncorrected estimations of the longitudinal forces and the lateral resistive forces caused by the skidding of the wheels in tracking trajectories.

Forward Velocity Estimation Algorithm for Planar Mobile Robots

  • Lee, Seung-Eun;Kim, Wheekuk;Yi, Byung-Ju;You, Bum-Jae
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.51.5-51
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    • 2001
  • The sliding and/or skidding motions generally occur to a car - like planar mobile robot consisting of four conventional fixed wheels attached on two parallel axles. Thus, the kinematic model of such mobile robot should include the description of skidding and sliding frictional motions. However, most of previous kinematic models do not take these frictional motions into account the kinematic model, as the work done by Muir and Newman [1]. Thus, does it result in least square solution in estimating sensed forward velocity. In this paper, the sensed forward velocity estimation algorithm for mobile robots is proposed, which not only includes those skidding and sliding frictional motions into kinematic model but also utilizes only the minimal set of dependent internal kinematic variables of the mobile robot. Then, ...

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