• Title/Summary/Keyword: Weight and Center of Gravity

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Body Impedance Control for Walking Stabilization of a Quadrupedal Robot (4족 보행 로봇의 걸음새 안정화를 위한 몸체 임피던스 제어)

  • Lee, Soo-Yeong;Hong, Ye-Seon
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.5
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    • pp.257-263
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    • 2000
  • One of the basic assumptions in the static gait design for a walking robot is that the weight of leg should be negligible compared to that of body, so that the total gravity center is not affected by swing of a leg. Based on the ideal assumption of zero leg-weight, conventional static gait has been simply designed for the gravity center of body to be inside the support polygon, consisting of each support leg's tip position. In case that the weight of leg is relatively heavy, however, while the gravity center of body is kept inside the support polygon, the total gravity center of walking robot can be out of the polygon due to weight of a swinging leg, which causes instability in walking. Thus, it is necessary in the static gait design of a real robot a compensation scheme for the fluctuation in the gravity center. In this paper, a body impedance control is proposed to obtain the total gravity center based on foot forces measured from load cells of a real walking robot and to adjust its position to track the pre-designed trajectory of the corresponding ideal robot's body center. Therefore, the walking stability is secured even in case that the weight of leg has serious influence on the total gravity center of robot.

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A Experimental Study on the Measurement and Estimation of Vehicle Center of Gravity (차량무게중심의 측정 및 추정에 관한 연구)

  • Lee, Myung-Su;Kim, Sang-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.91-99
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    • 2010
  • The center of gravity on vehicle is a fundamentally important point for assessing and measuring the characteristics of vehicle dynamics. Especially, the center of gravity height on vehicles is the closest factor with respect to rollover accidents in a social issue nowadays. In this paper, the center of gravity height in conjunction with vehicle parameters of vehicle weight, driving axle and roof height after measured by vehicle weight and loading location by means of VCGM developed by KATRI with good performance that the accuracy was less than 0.6% and repeatability 0.3% for vehicles being used in the whole world was observed. As a result of study, the location of center of gravity height on vehicle was able to be estimated with only roof height on vehicle.

Modeling of Self Camera Stick and Optimum Design (셀카봉 모델링과 최적설계)

  • YOON, JONGCHAN;JUNG, HEEOUK
    • Proceeding of EDISON Challenge
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    • 2015.03a
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    • pp.460-466
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    • 2015
  • The remaining features in this study using the Freecad proceeds according to the overall effect was not supported by the modeling Freecad were conducted a study to complement using the CATIA program or other commercially available. The focus of this study is that there can be obtained the stability through the center of gravity of the balancing of two parts by increasing the weight of the other magnet through a Fortuna other end of the weight of the bar, using the center of gravity. Finally, to find the optimal design of the weight and thickness of the main bar through the center of gravity balancing is the purpose of this study.

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A Study on the Effects of Weight and Center of Gravity of a Planing Craft on Running Attitude (활주선의 하중 및 무게 중심 위치 변화가 항주 자세에 미치는 영향에 대한 연구)

  • Kim, Dong-Jin;Rhee, Key-Pyo;Park, Han-Sol
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.3
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    • pp.335-342
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    • 2009
  • Motion characteristics of a planing craft are sensitively changed according to its weight and longitudinal center of gravity. In this paper, planing craft model tests were performed in calm water for various test conditions and Froude numbers. Sinkage and trim were measured to analyze the relations between the attitudes of a planing craft and the weight and center of gravity of it. Theoretical formula for the prediction of the attitudes of a prismatic planing hull was modified so that it can be applied to the prediction of the attitudes of a non-prismatic planing hull, and the calculation results by the modified formula were in good agreements with the experimental data.

Field Measurement of the Center of Gravity and the Moment of Inertia of Railway Vehicles Using Vibration (진동을 이용한 철도차량의 무게중심과 관성모멘트 현장 측정)

  • Song, Ki-Seok;Choi, Yeon-Sun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.10
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    • pp.878-884
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    • 2013
  • The center of gravity and the moment of inertia of railway vehicles are important parameters for running safety and stability in railway vehicle design. However, the exact measurement of those is difficult in manufacturing field. The weight measurement of a railway vehicle beneath the wheel using a weight scale is off by a large amount. This paper suggests a measurement method for the center of gravity and the moment of inertia of railway vehicles using vibration. For the measurement a railway vehicle is suspended using four wires. Direct measurement of the tension of the wires and the period of swinging motion of the suspended railway vehicle with calculations give the exact location of the center of gravity and the moment of inertia in x, y, and z directions, respectively. This implementation was demonstrated using an experimental device and verified numerically.

Analysis of Golf Ball Mobility and Balancing based on IoT Sports Environments

  • Lee, Tae-Gyu
    • International journal of advanced smart convergence
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    • v.8 no.3
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    • pp.78-86
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    • 2019
  • Recently, IoT researches using sensor data based on embedded networks in various fields including healthcare and sports have been continuously attempted. This study analyzes golf ball mobility to support IoT application in golf sports field. Generally, since the difference in density occurs due to the condition of the inner material and the abnormal state at the time of the outer skin joining during the manufacturing of the golf ball, the weight of each subset is equal for any two points with the same radius in the sphere cannot be guaranteed. For this reason, the deflected weight of the sphere has the undesirable effect of hitting the ball in a direction in which the weight of the ball is heavy. In this study, it is assumed that there is a unique center of gravity of the ball, and even if the golf ball cannot be manufactured perfectly, it wants to establish the basic principle to accurately recognize or mark the putting line based on the center of gravity. In addition, it is evaluated how the mobility of the golf ball with a deviation from the center of gravity of the golf ball affects the progress path (or movement direction) and the moving distance (or carry distance) after the golfer hits. The basic model of the mobility of the golf ball can help the golfer exercise model and the correlation analysis. The basic model of the mobility of the golf ball can help the golfer exercise model and the correlation analysis.

A Biomechanical Study on Kinetic Posture, Center-of-Gravity, Acceleration and their Effects on the Maximum Capability of Weight-lifting (역도경기의 자세, 무게중심, 가속도가 발휘근력에 미치는 영향에 관한 생체역학적 연구)

  • Lee, Myeon-U;Jeong, Gyeong-Ho;Han, Seong-Ho;Lee, Geung-Se;Lee, Chun-Sik
    • Journal of Korean Institute of Industrial Engineers
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    • v.11 no.2
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    • pp.87-99
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    • 1985
  • The purpose of this study is to analyze the changes in centers-of-gravity (COG), acceleration and body posture and their associated effects both on EMG and on the maximum capability of weight lifting during Clean & Jerk and Snatch motions. Displacement, velocity, acceleration of joints were obtained from film analysis. Also levels of exertions on 11 major muscle groups were obtained from EMG analysis during a lifting cycle. The EMG data were measured from Telemetry System which is useful in field experiments. Magnitude and direction of force, change in center-of-gravity were extracted from COG data which were measured from force platform. The results of this study can be to be useful both to coaches and to athletes in weight-lifting.

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Estimation of Weight Parameters for Small Fishing Vessels in Accordance with Loading Conditions (소형 어선의 재화상태를 고려한 중량 정보 추정 기법)

  • Kim, Dong Jin;Yeo, Dong Jin
    • Journal of Navigation and Port Research
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    • v.43 no.1
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    • pp.16-22
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    • 2019
  • This study proposed estimation methods for weight and center of gravity of small fishing vessels. Weights loaded on small fishing vessels were divided into fixed weights such as crew, fishing gear, and variable weights such as fuel, fresh water, provision, bait, and fish. Based on statistical analyses with weight data of several small fishing vessels, weight, longitudinal center of gravity (LCG), vertical center of gravity (KG) of each item were represented as linear functions of vessel gross tonnage. In addition, weighting factors of variable weights were added on estimation formulas in accordance with vessel loading conditions, e.g. full load departure condition. Estimation methods were verified using actual small fishing vessel data.

Study of the Center of Gravity in the Human Body and each Segment (인체 중심과 분절 중심에 대한 연구)

  • Chung Hyung-Kuk;Bae Sung-Soo
    • The Journal of Korean Physical Therapy
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    • v.5 no.1
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    • pp.61-69
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    • 1993
  • It was performed to encourage for Physical Therapist to apply the theory of center of the human body and segments in clinical situations. This study was investigated literarily on center of the human body and segments. Methods which search for the center-2 types, that is, method using reaction broad and segmental method-was suggested. The center location difference of gravity in human body depends on individual character. Generally, the center location is in kent of 2nd sacrum, that is, at $55\%$ of height from foot. The center of each segment is on 'link'. In the first place we must how the weight of segment we can search for the center easily. Mean segment coater location of extremities is at $42.33\%$ from each proximal end, and mean center of head and trunk lies at $45\%$.

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A study on shield on the center of gravity moving designed for high efficiency operation for the gamma-ray imaging detector (감마선 영상화 장치용 고효율 동작을 위한 차폐체 무게중심 이동 설계에 관한 연구)

  • Park, Gang-teck;Lee, Nam-ho;Hwang, Young-gwan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.948-949
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    • 2016
  • In this study, we perform the structure change of the shielding this is applied for gamma-ray detectors for imaging of gamma-ray source. Through previous studies, we implemented the commercially available gamma-ray imaging apparatus similar to the shielding body but weight reduction, center of gravity moving of shield. In this paper, we changed a shield for motion control detectors efficient movement. We performed the MCNP simulation of shield design and then we obtained the results of reducing the weight of the 17% and moving of center of gravity the shield center.

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