• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.7
• /
• pp.765-772
• /
• 1990

A practical method of identifying the inertial parameters, viscous friction and Coulomb friction of a robot is presented. The parameters in the dynamic equations of a robot are obtained from the measurements of the command voltage and the joint position of the robot. First, a dynamic model of the integrated system of the mainpulator and motor is derived. An off-line parameter identification procedure is developed and applied to the University of Minnesota Direct Drive Robot. To evaluate the accuracy of the parameters the dynamic tracking of the robot was tested. The trajectroy errors were significantly reduced when the identified dynamic parameters were used.

• International Journal of Highway Engineering
• /
• v.16 no.3
• /
• pp.43-50
• /
• 2014

PURPOSES : The dynamic modulus can be determined by applying the various theories from the Impact Resonance Testing(IRT) Method. The objective of this paper is to determine the best theory to produce the dynamic modulus that has the lowest error as the dynamic modulus data obtained from these theories(Complex Wave equation Resonance Method related to either the transmissibility loss or not, Dynamic Stiffness Resonance Method) compared to the results for dynamic modulus determined by using the Universal Testing Machine. The ultimate object is to develop the predictive model for the dynamic modulus of a Linear Visco-Elastic specimen by using the Complex Wave equation Resonance Method(CWRM) came up for an existing study(S. O. Oyadiji; 1985) and the Optimization. METHODS : At the destructive test which uses the Universal Testing Machine, the dynamic modulus results along with the frequency can be used for determining the sigmoidal master curve function related to the reduced frequency by applying Time-Temperature Superposition Principle. RESULTS : The constant to be solved from Eq. (11) is a value of 14.13. The reduced dynamic modulus obtained from the IRT considering the loss factor related to the impact transmissibility has RMSE of 367.7MPa, MPE of 3.7%. When the predictive dynamic modulus model was applied to determine the master curve, the predictive model has RMSE of 583.5MPa, MPE of 3.5% compared to the destructive test results for the dynamic modulus. CONCLUSIONS : Because we considered that the results obtained from the destructive test had the most highest source credibility in this study, the dynamic modulus data obtained respectively from DSRM, CWRM were compared to the results obtained from the destructive test by using th IRT. At the result, the reduced dynamic modulus derived from DSRM has the most lowest error.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.04b
• /
• pp.324-331
• /
• 2000

In this study, a new algorithm analyzing dynamic crack propagation problem by the coupling technique of Meshfree Method and Finite Element Method is proposed. The coupling procedure of two methods is presented with a short description of Meshfree Method especially, Element-free Galerkin (EFG) method. The elastodynamic fracture theory is presented, and a numerical implementation procedure for dynamic fracture analysis by Meshfree Method is also discussed. A couple of dynamic crack propagation problems illustrate the performance of the propsed technique. The accuracy of numerical solutions by the developed algorithm are compared with those of analytical solutions and experimental ones.

• Structural Engineering and Mechanics
• /
• v.64 no.2
• /
• pp.271-278
• /
• 2017

In this paper, we propose a new conjugate gradient method which possesses the global convergence and apply it to solve inverse problems of the dynamic loads identification. Moreover, we strictly prove the stability and convergence of the proposed method. Two engineering numerical examples are presented to demonstrate the effectiveness and speediness of the present method which is superior to the Landweber iteration method. The results of numerical simulations indicate that the proposed method is stable and effective in solving the multi-source dynamic loads identification problems of practical engineering.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.2
• /
• pp.318-327
• /
• 2010

This paper deals with analysis on dynamic characteristic and circuit parameter of linear switched reluctance motor by electromagnetic analytical method. Above all, using space harmonic method, which is electromagnetic method, the air-gap flux density is analyzed in the both align and unaign positions, and the inductance profile, force characteristic and resistance per phase are calculated by means of the process. The validity of the analyzed results are demonstrated by the finite element method(FEM) and manufacture of the prototype machine. Second, the dynamic simulation is analyzed by the use of circuit parameters derived from analytical method, and the operating system of the prototype machine is manufactured to demonstrated the validity of simulation analysis. As a result, it is considered that the characteristic equation suggested in this paper will contribute to the design, analysis and application of LSRM.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.6
• /
• pp.197-204
• /
• 2003

This paper presents an efficient modeling and dynamic analysis method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the inconvenience and numerical errors in association with re-meshing the structural model with the crack position changed. The proposed modeling method is validated through a series of simulation and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, two kinds of experiments are performed to validate the proposed modeling method. Finally, a diagnostic scheme fur open cracked beam structures is proposed and demonstrated through a numerical example.

• Structural Engineering and Mechanics
• /
• v.45 no.2
• /
• pp.201-209
• /
• 2013

A new dynamic reliability analysis of structure under repeated random loads is proposed in this paper. The proposed method is developed based on the idea that the probability density of several times random loads can be derived from the probability density of single-time random load. The reliability prediction models of structure based on time responses under several times random loads with and without strength degradation are obtained by using the stress-strength interference theory and probability density evolution method. The resulting differential equations in the prediction models can be solved by using the forward finite difference method. Then, the probability density functions of strength redundancy of the structures can be obtained. Finally, the structural dynamic reliability can be calculated using integral method. The efficiency of the proposed method is demonstrated numerically through a speed reducer. The results have shown that the proposed method is practicable, feasible and gives reasonably accurate prediction.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.5
• /
• pp.460-470
• /
• 2011

This paper presents a dynamic workspace control method of underwater manipulator considering a floating ROV (Remotely Operated vehicle) motion caused by sea wave. This method is necessary for the underwater work required linear motion control of a manipulator's end-effector mounted on a floating ROV in undersea. In the proposed method, the motion of ROV is modeled as nonlinear first-order differential equation excluded dynamic elements. For online manipulator control achievement, we develop the position tracking method based on sensor data and EKF (Extended Kalman Filter) and the input velocity compensation method. The dynamic workspace control method is established by applying these methods to differential inverse kinematics solution. For verification of the proposed method, experimental data based test of ROV position tracking and simulation of the proposed control method are performed, which is based on the specification of the KORDI deep-sea ROV Hemire.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.194-200
• /
• 2000

Researches on the FRF-based substructuring method have been mainly focused on vibratory response analysis. Present study is concerned about the application of the method to the dynamic stress analysis of a compressor mounting bracket in a passenger car. This is performed by using reaction forces that can be obtained by the FRF-based substructuring method. The air-conditioner system, composed of a compressor, a bracket and a test jig, is analyzed by using the FRF-based substructuring method. The experimental and numerical FRFs are combined to calculate the system responses and reaction forces at the connection point. The dynamic reaction forces plugged into the bracket FE model to compute the compute the stresses of the bracket. Dynamic stresses by the present method are compared with those from FE model. The comparison shows possibility of practical usage of the method for the real problem.

• Physical Therapy Rehabilitation Science
• /
• v.13 no.2
• /
• pp.240-249
• /
• 2024

Objective: The objective of this study is to evaluate various research that have examined dynamic knee valgus and to pinpoint a straightforward, clinically practical 2D assessment method for dynamic knee valgus that is user-friendly. Design: A literature review Methods: This literature review was conducted in Pubmed, MEDLINE^® and Google Scholar with the following key words: Knee valgus angle, Knee valgus evaluation, Knee valgus assessment, Dynamic knee valgus. After removing duplicate studies, 53 articles were initially chosen using this method, with 17 studies ultimately meeting the selection criteria. Results: Based on the comprehensive review of various studies, the Single Leg Squat (SLS) was identified as the most popular test method, followed by the Single Leg Landing (SLL) as the next most common test method. The Frontal Plane Projection Angle (FPPA) method was the most representative method for measuring dynamic knee valgus (DKV) during these tests. SLS was found in a total of 10 studies, while SLL was found in 7 studies. Conclusions: The most commonly proposed test for assessing DKV is measuring the SLS using the FPPA method. However, when applied to individuals without knee pathology, the discriminative power of this method may be limited. This suggests the need for further research to explore alternative methods for assessing DKV in this population.