• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1388-1400
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• 2004

Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are factors that could be potentially exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is newly proposed. This estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.921-924
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• 2005

Diesel generator sets with resilient mounts often experience resonances by major excitations which come from diesel engine and their foundation with rigid body modes. Because their natural frequency is determined by moment of inertia and stiffness of resilient mount vibration problems are resolved by changing location and stiffness of resilient mounts. But the calculated natural frequencies are inaccurate due to uncertainty of the inertia and mount stiffness. So this result can be useless on the design stage. In this paper, the stiffness of mount is evaluated on result from mount stiffness test in laboratory and generator set vibration test and a simple calculation method for moment of inertia is proposed. Based on these data, the procedure to select optimized mount stiffness and location on the design stage is set up.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.801-804
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• 2006

The purpose of this paper is to investigate the stability of stepped cantilever columns with a tip mass of rotatory inertia and a translational spring at one end. The column model is based on the Bernoulli-Euler theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibration of columns with stepwise variable cross-section and subjected to a subtangential follower force is solved numerically using the corresponding boundary conditions. And the bisection method is used to calculate the critical divergence/flutter load. The frequency and critical divergence/flutter load for the stepped column with a single step are presented as functions of various non-dimensional system parameters: the segmental length parameter, the section ratio, the subtangential parameter, the mass, the moment of inertia of the mass, and the spring parameter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.204-208
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• 2001

Position control of the electro-hydraulic servo indexing system in a flexible forging machine was investigated Flexible forging machine forges an axial type workpiece in the radial direction as well as in the axial direction. The role of the indexing system is to rotate a workpiece fast and accurately to a desired position for continuous shaping. Since the inertia of a workpiece changes during each forging step, a control technique which is robust to inertia variation should be adopted to the position control of the workpiece. In this study, time delayed control technique is applied to the servo system. Time delayed control method does not depend on estimation of specific parameters. Rather, it depends on the direct estimation of a function representing the effect of uncertainties. Direct estimation is accomplished using time delay and the gathered information is used to cancel the unknown dynamics is accomplished using disturbances simultaneously. Experimental result show that the time delayed controller is robust to inertia variation of the load, and satisfactory performance on the sposition accuracy is obtained compared to the contentional feedback control.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.99-104
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• 2002

DQM(differential quadrature method) is applied to computation of eigenvalues of the equations of motion governing the free in-plane vibration for circular curved beams including mid-surface extension and the effects of rotatory inertia. Fundamental frequencies are calculated for the members with various end conditions and opening angles. The results are compared with numerical solutions by other methods for cases in which they are available. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.2
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• pp.13-22
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• 2003

To coordinate the robot manipulator along the desired trajectory, the exact model of the dynamics is required. The added mass and added moment of inertia, buoyancy, drag force, and friction mainly affect the dynamics of the undersea robot manipulator, and they are quite complex and unknown. In this reason. the exact model of the undersea robot manipulator is difficult to obtain. In this paper, instead of having efforts to get the exact model of the robot dynamics, a control-based approach was performed. We modeled the dynamics of the undersea robot manipulator whose parameters are unknown, and then applied a proposed direct adaptive and robust control, which is different from previous studies. The unknown added mass, and added moment of inertia, drag force and friction are estimated by the direct adaptive control scheme, and the drag force which is dominant disturbance is compensated by the robust control. Also, stability of the proposed control scheme is analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.1-6
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• 2002

Engine lubrication system is generally affected by vehicle driving conditions, which are composed of acceleration, braking deceleration and accelerating during cornering. The major reason is due to the oil pan system in which oil is directly influenced by inertia farce caused by vehicle driving conditions. Therefore, to confirm safety of engine lubrication system inertia farce effects are also considered in the developing state. For the purpose, we have carried the engine tilting tests using ourselves made test rig. Verifying the test results we also measured the inertia effects on the engine lubrication system using the circular tuning and slalom test with vehicle. Through the comparison study between two kinds of results we obtained that the engine tilting test rig was very useful to confirm the safety evaluation of engine lubrication system.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.1-12
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• 2002

This paper considers the robust and optimal three-axis attitude stabilization of rigid spacecraft with inertia uncertainties. The attitude motion of rigid spacecraft described in terms of either the Cayley-Rodrigues parameters or the Modified Rodrigues parameters is considered. A class of robust nonlinear control laws with relaxed feedback gain structures is proposed for attitude stabilization of rigid spacecraft with inertia uncertainties. Global asymptotic stability of the proposed control laws is shown by using the LaSalle Invariance Principle. The optimality properties of the proposed control laws are also investigated by using the Hamilton-Jacobi theory. A numerical example is given to illustrate the theoretical results presented in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1777-1782
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• 2011

Brushless DC motors applied in many control systems because of the good respose characteristic and the easy control characteristic. The speed control of the BLDC motors is important in the systems. This paper has designed PSO-PID speed controller for the speed control of BLDC motors. The PSO algorithm optimized the parameters of the PID controller in the PSO-PID speed controller. The several methods obtained the optimal inertia weight of the PSO algorithm by comparison. The optimal inertia weight of the PSO algorithm optimized the PSO-PID speed controller for BLDC motors. This paper confirmed the performance of proposed PSO-PID speed controller through simulation results.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.459-477
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• 2011

Due to the low elastic modulus of FRP, concrete members reinforced with FRP rebars show greater deflections than members reinforced with steel rebars. Deflection is one of the important factors to consider the serviceability of horizontal members. In this study flexural test of AFRP reinforced concrete beams was performed considering reinforcement ratio and compressive strength as parameters. The test results indicated that flexural capacity and stiffness increase in proportion to the reinforcement ratio. The test results were compared with existing proposed equations for the effective moment of inertia including ACI 440. The most of the proposed equations were found to over-estimate the effective moment of inertia while the equation proposed by Bischoff and Scanlon (2007) most accurately predicted the values obtained through actual testing.