• Title/Summary/Keyword: kinematic model

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Vehicle Dynamics Modeling and Correlation Using the Kinematic and Compliance Test of the Suspension (현가장치 기구정역학 시험에 의한 차량동역학 모델링 및 시험검증)

  • Kim Sangsup;Jung Hongkyu
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.109-118
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    • 2005
  • A functional suspension model is proposed as a kinematic describing function of the suspension that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.

A Study of Human Model Based on Dynamics (동력학기반 인체 모델 연구)

  • 김창희;김승호;오병주
    • Journal of Biomedical Engineering Research
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    • v.20 no.4
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    • pp.485-493
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    • 1999
  • Human can generate various posture and motion with nearly 350 muscle pairs. From the viewpoint of mechanisms, the human skeleton mechanism represents great kinematic and dynamical complexity. Physical and behavioral fidelity of human motion requires dynamically accurate modeling and controling. This paper describes a mathematical modeling, and dynamic simulation of human body. The human dynamic model is simplified as a rigid body consisting of 18 actuated degrees of freedom for the real time computation. Complex kinematic chain of human body is partitioned as 6 serial kinematic chains that is, left arm, right arm, support leg, free leg, body, and head. Modeling is developed based on Newton-Euler formulation. The validity of proposed dynamic model, which represents mathematically high order differential equation, is verified through the dynamic simulation.

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Analysis on Kinematic Characteristics for a Translational 3-DOF Parallel Mechanism with Constrained Stewart Platform Structure (스튜워트 플랫폼 구조를 이용한 병진 3-자유도 병렬 메커니즘의 기구학 특성 분석)

  • 이석희;김희국;이병주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.525-529
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    • 2004
  • A novel translational 3-dof parallel mechanism is proposed and analyzed. The mechanism consists of three RRPS serial subchains and an additional passive 3-dof type serial subchain. Three RRPS serial subchains alone may form a structure of the 6-DOF Stewart Platform mechanism. However, in the proposed mechanism, an additional passive serial subchain acts as constraints to restrict the output motion of the mechanism in 3-DOF translational space. The closed form position solutions of the proposed mechanism and its first-order kinematic model are derived. Then its workspace size and kinematic characteristics are examined via kinematic isotropic index.

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Analysis on Kinematic Characteristics for a Spherical 3-DOF Parallel Mechanism with Constrained Stewart Platform Structure (스튜워트 플랫폼 구조를 이용한 구형 3-자유도 병렬 메커니즘의 기구학 특성 분석)

  • 이석희;김희국;이병주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.520-524
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    • 2004
  • In this work, a novel spherical 3-dof parallel mechanism is proposed and analyzed. The mechanism consists of three RRPS serial subchains and an additional passive 3-dof type serial subchain. Three RRPS serial subchains alone may form a structure of 6-DOF Stewart Platform mechanism. However, in the proposed mechanism, an additional passive serial subchain acts as constraints to restrict the output motion of the mechanism within 3-DOF spherical space. The closed form solutions of position analysis of the proposed mechanism and its first-order kinematic model are derived. Then its workspace size and kinematic characteristics are examined via kinematic isotropic index.

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Notch Strain Analysis of Cruciform Welded Joint using Nonlinear Kinematic Hardening Model (비선형 이동 경화모델을 이용한 십자형 필릿 용접부의 변형율 해석)

  • Kim, Yooil;Kim, Kyung-Su
    • Journal of the Society of Naval Architects of Korea
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    • v.50 no.1
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    • pp.41-48
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    • 2013
  • Several fatigue damages have recently been reported which cannot be resolved in the context of the existing fatigue design procedure, and they are suspected to be the cracks induced by the low cycle fatigue mechanism. To tackle the problem, a series of material tests together with fatigue tests have been carried out, and elasto-plastic notch strain analysis using nonlinear kinematic hardening model has been performed. The cyclic stress-strain curves are obtained and the nonlinear kinematic hardening model was calibrated based on the obtained material data. Also, the fatigue test with non-load-carrying cruciform fillet welded joint has been performed in low cycle fatigue regime. Then, the notch strain analyses have been carried out to find the precise elasto-plastic behavior of the material at the notch root of the cruciform joint. The variation of the material property from the base metal via HAZ up to the weld metal was taken into account using spatial variation of the material property. Then the detail elasto-plastic behavior of the welded joint subjected to the repeated cyclic loading has been investigated further through the comparison with the prediction with Neuber's rule. The calibration of the nonlinear kinematic hardening model and nonlinear notch strain analyses have been performed using the commercial FE program ABAQUS.

Analysis on Kinematics and Dynamics of Human Arm Movement Toward Upper Limb Exoskeleton Robot Control Part 1: System Model and Kinematic Constraint (상지 외골격 로봇 제어를 위한 인체 팔 동작의 기구학 및 동역학적 분석 - 파트 1: 시스템 모델 및 기구학적 제한)

  • Kim, Hyunchul;Lee, Choon-Young
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.12
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    • pp.1106-1114
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    • 2012
  • To achieve synchronized motion between a wearable robot and a human user, the redundancy must be resolved in the same manner by both systems. According to the seven DOF (Degrees of Freedom) human arm model composed of the shoulder, elbow, and wrist joints, positioning and orientating the wrist in space is a task requiring only six DOFs. Due to this redundancy, a given task can be completed by multiple arm configurations, and thus there exists no unique mathematical solution to the inverse kinematics. This paper presents analysis on the kinematic and dynamic aspect of the human arm movement and their effect on the redundancy resolution of the human arm based on a seven DOF manipulator model. The redundancy of the arm is expressed mathematically by defining the swivel angle. The final form of swivel angle can be represented as a linear combination of two different swivel angles achieved by optimizing different cost functions based on kinematic and dynamic criteria. The kinematic criterion is to maximize the projection of the longest principal axis of the manipulability ellipsoid for the human arm on the vector connecting the wrist and the virtual target on the head region. The dynamic criterion is to minimize the mechanical work done in the joint space for each two consecutive points along the task space trajectory. As a first step, the redundancy based on the kinematic criterion will be thoroughly studied based on the motion capture data analysis. Experimental results indicate that by using the proposed redundancy resolution criterion in the kinematic level, error between the predicted and the actual swivel angle acquired from the motor control system is less than five degrees.

Motion Planning Algorithms for Kinematically Redundant Manipulator Not Fixed to the Ground (지면에 고정되어 있지 않은 여유자유도 매니플래이터의 운동계획 알고리즘)

  • 유동수;소병록;김희국
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.10
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    • pp.869-877
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    • 2004
  • This paper deals with motion planning algorithm for kinematically redundant manipulators that are not fixed to the ground. Differently from usual redundant manipulators fixed to the ground, the stability issue should be taken into account to prevent the robot from falling down. The typical ZMP equation, which is employed in human walking, will be employed to evaluate the stability. This work proposes a feed forward ZMP planning algorithm. The algorithm embeds the 'ZMP equations' indirectly into the kinematics of the kinematic model of a manipulator via a ZMP stability index The kinematic self motion of the redundant manipulator drives the system in such a way to keep or plan the ZHP at the desired position of the footprint. A sequential redundancy resolution algorithm exploiting the remaining kinematic redundancy is also proposed to enhance the performances of joint limit index and manipulability. In addition, the case exerted by external forces is taken into account. Through simulation for a 5 DOF redundant robot model, feasibility of the proposed algorithms is verified. Lastly, usual applications of the proposed kinematic model are discussed.

A Study on the Application of Machine Simulation and Angle Milling Head of a 6-Axis Parallel Kinematic Machine (6축 병렬기구 공작기계의 머신 시뮬레이션과 앵글밀링헤드 적용에 관한 연구)

  • Lee, In-Su;Kim, Hae-Ji;Kim, Nam-Kyung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.5
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    • pp.47-54
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    • 2017
  • This study examines the implementation of a kinematic machining tool to evaluate the interference and collision phenomenon of 5-axis machining of wing ribs from airplanes, particularly for a large-size model airplane. We develop a machine simulation model of a parallel kinematic machining tool that can operate in a virtual space, which is equivalent to the authentic conditions in the field. The investigation of the simulation function elements indicates the necessity to generate the 6-axis machining, which attaches an angle head to the main axis of the machine. Using an NC program for the wing ribs, we attempt to verify the correspondence and conformity between the machine simulation model and the actual equipment.

A Path Tracking Control Algorithm for Autonomous Vehicles (자율 주행차량의 경로추종 제어 알고리즘)

  • 안정우;박동진;권태종;한창수
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.4
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    • pp.121-128
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    • 2000
  • In this paper, the control algorithm fur an autonomous vehicle is studied and applied to an actual 2 wheel-driven vehicle system. In order to control a nonholonomic system, the kinematic model for an autonomous vehicle is constructed by relative velocity relationship about the virtual point at distance from the vehicle's frame. And the optimal controller that based on the kinematic model is operated on purpose to track a reference vehicle's path. The actual system is designed with named 'HYAVI' and the system controller is applied. Because all the results of simulation don't satisfy the driving conditions of HYAVI, a reformed control algorithm that satisfies an actual autonomous vehicle is applied at HYAVI. At the results of actual experiments, the path tracking works very well by the reformed control algorithm. An autonomous vehicle that applied this control algorithm can be easily used for a path generation algorithm.

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Development of an Efficient Vehicle Dynamics Model Using Massless Link of a Suspension (현가장치 무질량 링크를 이용한 효율적인 차량동역학 모델 개발)

  • Jung Hongkyu;Kim Sangsup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.99-108
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    • 2005
  • This paper represents an efficient modeling method of a suspension system for the vehicle dynamic simulation. The suspension links are modeled as composite joints. The motion of wheel is defined as relative one degree of freedom motion with respect to car body. The unique relative kinematic constraint formulation between the car body and wheel enables to derive equations of motion in terms of wheel vertical motion. Thus, vehicle model has ten degrees of freedom. By using velocity transformation method, the equations of motion of the vehicle is systematically derived without kinematic constraints. Various vehicle simulation such as J-turn, slowly increasing steer, sinusoidal sweep steer and bump run has been performed to verify the validity of the suggested vehicle model.