• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.183-186
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• 2005

We developed an upwind numerical formulation based on the eigenvalues of the approximate Jacobian matrix in order to solve the hyperbolic conservation laws governing the two-fluid two-phase flow models. We obtained eight analytic eigenvalues in the two dimensions that can be used for estimate of the wave speeds essential in constructing an upwind numerical method. Two-dimensional underwater cavitation in a flow past structural shapes or by underwater explosion can be solved using this method. We present quantitative prediction of cavitation for the water tunnel wall and airfoils that has both experimental data as well as numerical results by other numerical methods and models.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.207-210
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• 2000

Singular points are those at which the determinant of a Jacobian matrix is zero. A parallel manipulator gains mostly an extra DOF at the singular points, where it can not be properly controlled. In this study, singular points of a cubic parallel manipulator are illustrated by obtaining the determinant of a Jacobian matrix mathematically, and the singular points of the manipulator are found to be three separate planes in a 3D space. The dependency among links for each singular point is determined by applying linear algebra. Also, the singular points and workspace of the cubic parallel manipulator are plotted to check if the workspace contain singular points.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.2
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• pp.18-28
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• 2001

Super computers has been utilized to carry out vehicle dynamics in real time. This research propose an implicit integra-tion method for vehicle state variables. Newton chord method is empolyed to solve the equations of motion and con-straints. The equations of motion and constraints are formulated such that the Jacobian matrix for Newton chord method is needed to be computed only once for a dynamic analysis. Numerical experiments showed that the Jacobian matrix generat-ed at the initial time could have been utilized for the Newton chord iterations throughout simulations under various driving conditions. Convergence analysis of Newton chord method with the proposed Jacobian updating method is carried out. The proposed algorithm yielded accurate solutions for a prototype vehicle multibody model in realtime on a 400 MHz PC compatible.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.479-484
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• 1992

The resolved motion rate control (RMRC) is converting to Joint space trajectory from given Cartesian space trajectory. The RMRC requires the inverse of Jacobian matrix. Since the Jacobian matrix of the redundant robot is generally not square, the pseudo-inverse must be introduced. However the pseudo-inverse is not easy to be implemented on a digital computer in real time as well as mathematically complex. In this paper, a simple fuzzy resolved motion rate control (FRMRC) that can replace the RMRC using pseudo-inverse of Jacobian is proposed. The proposed FRMRC with appropriate fuzzy rules, membership functions and reasoning method can solve the mapping problem between the spaces without complexity. The mapped Joint space trajectory is sufficiently accurate so that it can be directly used to control redundant manipulators. Simulation results verify the efficiency of the proposed idea.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.109-121
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• 1996

This paper presents how the input forces along the prismatic joints of a parallel manipulator are transmitted to the upper platform. In order to consider force transmission and moment transmission seperately the Jacobian matrix for parallel manipulators is splitted into two parts. Magnitudes of input forces on the six actuators at a given manipulator configuration which generate maximum/minimum output force with no moment generated on the platform are obtained through the singular value decomposition of a matrix involving the Jacobian. Similarly the directions of the input forces to obtain only the rotation of the platform have been analyzed. Using the singular values a simple equation for the volume of ellipsoid which is a good tool for manipulability measure is provided. Obtained results could be useful in determinimg design parameters like radius of plaform, angles between joints, etc. Simulations are porvided.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.576-579
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• 2002

This paper presents the jacobian analysis of new type Casing Oscillator using the inverse kinematics, and to search for it's singularities through the jacobian analysis. All parallel manipulator have some singularities in workspace or it's outside workspace. Singularities were cleared by many other study of parallel manipulator f3r that reason recent publication of device control. In this paper defined that singularities of new file of Casing Oscillator and, to show it's graph. Finally this paper will be used for a practical example for construction spot, aviation simulator, vehicles simulator, military equipment etc.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.32-35
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• 2004

In boundary estimation in Electrical Impedance Tomography (EIT), conventional method is the modified Newton Raphson (mNR) method .The mNR is famous for good method since has good convergence and robustness against noisy data. But the mNR is low efficiency to get and update Jacobian matrix. So, the mNR become very slow algorithm. We propose the Quasi Newton (QN) method to improve efficiency which will lead to speed up in boundary estimation. The QN can improve a low efficiency by using estimated Jacobian matrix contrary to using exactly calculated Jacobian matrix, this used by the mNR. And finally, we propose the modified Quasi Newton (mQN) method because the QN has some problems such as bad early convergence rate and instability of 'divided by zero'. For the verification of the propose method, numerical experiments are conducted and the results show a good performance.

• Journal of Power Electronics
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• v.19 no.3
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• pp.655-664
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• 2019

In order to analyze the nonlinear phenomena of the bifurcation and chaos caused by the switching of nonlinear switching devices in inductively coupled power transfer (ICPT) systems, a Jacobian matrix model, based on discrete mapping numerical modeling, is established to judge the system stability of the periodic closed orbit and to study the nonlinear behavior of Hopf bifurcation in a system under full resonance. The general flow of the parameter design, based on the stability principle for ICPT systems, is proposed to avoid the chaos and bifurcation phenomena caused by unreasonable parameter selection. Firstly, based on the state equation of SS-type compensation, a three-dimensional bifurcation diagram with the coupling coefficient as the bifurcation parameter is established with a numerical simulation to observe the nonlinear phenomena in the system. Then Filippov's method based on a Jacobian matrix model is adopted to deduce the boundary of stable operation and to judge the type of the bifurcation in the system. Then the general flow of the parameter design based on the stability principle for ICPT systems is proposed through the above analysis to realize stable operation under the conditions of weak coupling. Finally, an experimental platform is built to confirm the correctness of the numerical simulation and modeling.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.1
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• pp.5-10
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• 2001

A method is proposed to obtain the Jacobian matrix of the 5 -bar parallel manipulator by employing the orthogonality between position and velocity vectors of rotating rigid-body around a fixed point. The dynamics of the 5-bar parallel manipulator is analyzed and utilized to design the computed-torque controller by developing a transformation matrix of the passive joints with respect to the active ones. In experimental demonstration, it shows that high-speed and accuracy tasks are performed by the proposed computed-torque control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1433-1441
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• 2009

In multibody dynamic analysis, one of the most important problems is to reduce computation times for real-time simulation. This paper presents the derivation procedure of equations of motion of a 6${\times}$6 autonomous vehicle in terms of chassis local coordinates which do not require coordinates transformation matrix to enhance efficiency for real-time dynamic analysis. Also, equations of motion are derived using the VT(velocity transformation) technique and symbolic computation method coded by MATLAB. The Jacobian matrix of the equations of motion of a system is derived from symbolic operations to apply the implicit integration method. The analysis results were compared with ADAMS results to verify the accuracy and approve the feasibility of real time analysis.