• Structural Engineering and Mechanics
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• v.45 no.4
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• pp.423-437
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• 2013

Complex structures are usually assembled from several substructures with joints connecting them together. These joints have significant effects on the dynamic behavior of the assembled structure and must be accurately modeled. In structural analysis, these joints are often simplified by assuming ideal boundary conditions. However, the dynamic behavior predicted on the basis of the simplified model may have significant errors. This has prompted the researchers to include the effect of joint stiffness in the structural model and to estimate the stiffness parameters using inverse dynamics. In the present work, structural joints have been modeled as a pair of translational and rotational springs and frequency equation of the overall system has been developed using sub-structure synthesis. It is shown that using first few natural frequencies of the system, one can obtain a set of over-determined system of equations involving the unknown stiffness parameters. Method of multi-linear regression is then applied to obtain the best estimate of the unknown stiffness parameters. The estimation procedure has been developed for a two parameter joint stiffness matrix.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.754-758
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• 1996

In this paper, a new method of position synchronizing control is proposed for multi-axes driving system. The proposed synchronizing control system is constituted with speed and synchronizing controller. The structure of synchronizing control system is varied by sign of synchronizing error. When a disturbance input becomes added to one axis, this axis becomes slave axis. The other axis is master axis. Therefore, master axis is not influenced by the disturbance. The speed controller of the first axis is designed by $H_{\infty}$ control theory. The speed controller of the second axis is designed by inverse dynamics of speed control system of the first axis. The speed control system designed with $H_{\infty}$ controller guarantees low sensitivity for the disturbance as well as robustness against model uncertainties. Especially, the synchronizing controller is designed to keep position error to minimize by controlling speed of slave axis. The effectiveness of the proposed method is successfully confirmed through several experiments.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.156-158
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• 2009

A graphic simulator is efficient to see what will happen to the target robot. But it is not exactly same as the real world. Because there are so many physical laws to be concerned. In this paper, we propose a simulator with physics engine to create motions for quadruped robot. It is not only to show more real simulations but also to be more efficient for teaching motions to quadruped robot. To solve the quadruped robot's dynamics or inverse kinematics, It takes much times and hard effort. Using physics engine make it easy to setup motions without calculating inverse kinematics or dynamics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.9-13
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• 1997

This parer is a study on the inverse dynamics of a one-link flexible robot arm which is controlled by translational base motion. The system is composed of a flexible arm, a base for driving arm, a DC servomotor, and a computer. The arm base is moved so that the arm tip follows a desired function. The governing equations are based on the Bernoullie-Euler beam theory and solved by applying the Laplace transform method and then the numerical inversion method. Moter voltage is obtained by simulation for tip trajectory functions i. e. Bang-Bang, Cosine and Gauss Function. And, the tip motion is measured while simulation results are applying. Then the results are investigated to select most proper input and to compare their chateristics. Experimental results show the Cosine function is most proper with respect to low maximum voltage and steady state error.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.136-146
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• 1992

This paper provides the end-point positioning of a single-link flexible robot arm by inverse dynamics. The system is composed of a flexible arm, the mobile ballscrew stage as an arm base, a DC servomotor as an actuator, and a computer. Actuator voltages required for the model of a flexible arm to follow a given tip trajectory are formulated on the basis of the Bermoullie-Euler beam theory and solved by applying the Laplace transform method, and computed by the numerical inversion method proposed by Weeks. The mobile stage as the arm base is shifted so that the end-point follows the desired trajectories. Then the trajectory of end-point is measured by the laser displacement sensor. Here, two kinds of functions are chosen for the given tip trajectories. One is what is called the bang-bang acceleration profile and the other is the Gaussian velocity profile.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.82-89
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• 1997

In this paper, an adaptive speed controller with an FNN(Feedforward Neural Network) is proposed for servo motor drives. Generally, the motor system has nonlinearities in friction, load disturbance and magnetic saturation. It is necessary to treat the nonlinearities for improving performance in servo control. The FNN can be applied to control and identify a nonlinear dynamical system by learning capability. In this study, at first, a robust speed controller is developed by Lyapunov stability theory. However, the control input has discontinuity which generates an inherent chattering. To solve the problem and to improve the performances, the FNN is introduced to convert the discontinuous input to continuous one in error boundary. The FNN is applied to identify the inverse dynamics of the motor and to control the motor using coordination of feedforward control combined with inverse motor dynamics identification. The proposed controller is developed for an SR motor which has highly nonlinear characteristics and it is compared with an MRAC(Model Reference Adaptive Controller). Experiments on an SR motor illustrate te validity of the proposed controller.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2043-2050
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• 1993

This paper presents a three dimensional modeling and dynamic analysis of a hydraulic excavator. An excavator composed of a boom, a bucket, two boom cylinders, an arm cylinder, and a bucket cylinder is used for the analysis. Each cylinder is modeled to two separate bodies linked by a translational joint. Judging from the actual degrees of freedom of the excavator, proper kinematic joints are selected to exclude redundant constraints in the modeling. In order to find the reaction forces at kinematic joints during operations, inverse dynamic analysis is carried out. Dynamic analysis is also carried out to verify the results from inverse dynamic analysis. The DADS program is used for analysis, with proper modification of the DADS user routine according to various motions.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.881-886
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• 2004

This paper presents the inverse dynamic analysis of the wheel loader manipulator based on the experimental data. A three dimensional rigid multi-body model of the wheel loader manipulator was built up. The inverse dynamic analysis for the typical operation mode was carried out by the ADAMS program. In order to verify the analysis result with the measured one, the hydraulic pressure and displacements of the cylinders were measured and the inverse dynamic analysis was carried out using experimental data. From the results of the analysis and measurement, it was concluded that the computational driving force showed good agreement with the measured one.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1311-1312
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1627-1628
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• 2013