• 한국자동차공학회논문집
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• 제13권1호
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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.

• 대한기계학회논문집
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• 제18권12호
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• pp.3253-3269
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• 1994

In this paper a new concept, named the Extended Operational Space Formulation, has been proposed for the effective analysis and real-time control of the robot manipulators with kinematic redundancy. The extended operational space consists of operational space and optimal null space. The operational space is used to describe robot end-effector motion; whereas the optimal null space, defined as the target space of the self motion manifold, is used to express the self motion for the secondary tasks. Based upon the proposed formulation, the kinematics, statics, and dynamics of redundant robots have been analyzed, and an efficient control algorithm has been proposed. Using this algorithm, one can optimize a performance measure while tracking a desired end-effector trajectory with a better computational efficiency than the conventional methods. The effective ness of the proposed method has been demonstrated with simulations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.573-578
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• 2004

This paper presents a methodology for the stiffness analysis of a low-DOF parallel manipulator. A low-DOF parallel manipulator is a spatial parallel manipulator which has less than six degrees of freedom. The reciprocal screws of actuations and constraints in each leg can be determined by making use of the theory of reciprocal screws, which provide information about reaction forces due to actuations and constraints. When pure force is applied to a leg, the leg stiffness is modeled as a linear spring along the line. For pure couple, it is modeled as a rotational spring about the axis. It is shown that the stiffness model of an F-DOF parallel manipulator consists of F springs related to actuations and 6-F springs related to constraints connected from the moving platform to the base in parallel. The $6{\times}6$ Cartesian stiffness matrix is obtained, which is the sum of the Cartesian stiffness matrices of actuations and constraints. Finally, a 3-UPU parallel manipulator is used as an example to demonstrate the methodology.

• 대한기계학회논문집A
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• 제29권5호
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• pp.680-688
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• 2005

This paper presents a methodology for the stiffness analysis of a low-DOF parallel manipulator. A low-DOF parallel manipulator is a spatial parallel manipulator which has less than six degrees of freedom. The reciprocal screws of actuations and constraints in each leg can be determined by making use of the theory of reciprocal screws, which provide information about reaction forces due to actuations and constraints. When pure farce is applied to a leg, the leg stiffness is modeled as a linear spring along the line. For pure couple, it is modeled as a rotational spring about the axis. It is shown that the stiffness model of an it_DOF parallel nipulator consists of F springs related to actuations and 6-F springs related to constraints connected from the moving platform to the base in parallel. The 6x f Cartesian stiffness matrix is derived, which is the sum of the Cartesian stiffness matrices of actuations and constraints. Finally, the 3-UPU, 3-PRRR, and Tricept parallel manipulators are used as examples to demonstrate the methodology.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.409-414
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• 2007

Nowadays, with the advancement of computational mechanics, and vehicle dynamics simulation linked up with virtual testing laboratory(VTL) and virtual proving ground(VPG) technologies has become a useful method for analyzing numerous driving performances and diverse noise/vibration characteristics. In this paper, the analytical vehicle model based on multi-body dynamics theory was developed to investigate the vibration characteristics according to various road conditions. For the purpose, the whole vehicle parameters, each vehicle's part parameter, and part connecting elements such as spring, damper, and bush were measured by an experiment. Also, the vehicle dynamics model, which includes the front suspension, rear suspension, steering, front wheel, rear wheel, and body subsystems has been constructed for computer simulation. With the developed vehicle dynamics model, three forces and three moments measured at each wheel center were applied to evaluate and analyze dynamics and vibration characteristics for miscellaneous road conditions.

• 대한기계학회논문집A
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• 제36권9호
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• pp.1003-1008
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• 2012

실시간 차량동역학 해석을 위해서는 효율적인 차량 모델이 필요하게 된다. 효율성을 높이기 위해 집중질량모델로 가정하면 현가장치의 특성을 고려하기 어렵게 되며, 현가장치의 특성을 모두 고려한 다물체동역학 모델에서는 효율성이 떨어진다. 그러므로 본 논문에서는 다물체동역학 모델링을 사용하되 해석의 효율성을 저하시키는 현가장치의 각종 요소들의 효과는 기구정역학 실험으로 추출된 특성그래프로 대체함으로써 효율성도 기하고자 시도하였다. $6{\times}6$ 차량을 차체와 휠로 구성된 차량으로 모델을 정의하였고, 다물체동역학 모델인 ADAMS 결과와 비교하여 실험적 모델의 유용성을 검증하였다. 그리고 검증된 실험적 차량모델을 RT-LAB을 활용한 실시간 시뮬레이션 환경에 삽입하여, 실시간성 시뮬레이션의 가능성을 검증하였다.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.200-208
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• 1999

The statics relation of the Stewart platform has been investigated from the viewpoint of the forward and inverse force transmission analyses. Two eigenvalue problems corresponding to the forward and inverse force transmission analyses have been formulated. The forward force transmission analysis is to determine the ranges of the magnitudes of the force and moment generated at the end-effector for the given magnitude of linear actuator forces. In reverse order, the inverse force transmission analysis is to find the range of the magnitude of actuator forces for the given ranges of the magnitudes of the force and moment at the end-effector. The inverse force transmission analysis is important since it can provide a designer with a valuable information about how to choose the linear actuators. It has been proved that two eigenvalue problems have a reciprocal relation, which implies that solving either of the eigenvalue problems may complete the forward/inverse force transmission analysis. A numerical example has been also presented.