• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.76-82
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• 2004

The solutions of neighboring optimal control are typically obtained using the sweep method or transition matrices. Due to the numerical integration, however, the gain matrix can become infinite as time go to final one in the transition matrices, and the Riccati solution can become infinite when the final time free. To overcome these disadvantages, this paper proposes the pseudospectral Legendre method which is to first discreteize the linear boundary value problem using the global orthogonal polynomial, then transforms into an algebraic equations. Because this method is not necessary to take any integration of transition matrix or Riccati equation, it can be usefully used in real-time operation. Finally, its performance is verified by the numerical example for the space vehicle's orbit transfer.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.243-256
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• 2007

This paper deals with determining the sufficient conditions of minimum for the class of problems in which the necessary conditions of optimum are satisfied in the strengthened form Legendre-Clebsch. To this paper, we shall use the sweep method which analysis the conditions of existence of the conjugated points on the optimal trajectory. The study we have done evaluates the command variation on the neighboring optimal trajectory. The sufficient conditions of minimum are obtained by imposing the positivity of the second variation. The results that this method offers are applied to the problem o the orbital rendez-vous for the linear case of the equations of movement.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.152-158
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• 2005

This paper describes a reactive optimal power flow incorporating margin enhancement constraints. Margin sensitivity at a steady-state voltage instability point is calculated using invariant space parametric sensitivity, and it can provide valuable information for selection of effective control parameters. However, the weakest buses in neighboring regions have high margin sensitivities within a certain range. Hence, the control determination using only the sensitivity information might cause violation of operational limits of the base operating point, at which the control is applied to enhance voltage stability margin in the direction of parameter increase. This paper applies an interior point method (IPM) to solve the optimal power flow formulation with the margin enhancement constraints, and shunt capacitances are mainly considered as control variables. In addition, nonlinearity of margin enhancement with respect to control of shunt capacitance is considered for speed-up control determination in the numerical example using the IEEE 118-bus test system.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.174-174
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• 2000

Q-learning, based on discrete state and action space, is a most widely used reinforcement Learning. However, this requires a lot of memory and much time for learning all actions of each state when it is applied to a real mobile robot navigation using continuous state and action space Region-based Q-learning is a reinforcement learning method that estimates action values of real state by using triangular-type action distribution model and relationship with its neighboring state which was defined and learned before. This paper proposes a new Region-based Q-learning which uses a reward assigned only when the agent reached the target, and get out of the Local optimal path with adjustment of random action rate. If this is applied to mobile robot navigation, less memory can be used and robot can move smoothly, and optimal solution can be learned fast. To show the validity of our method, computer simulations are illusrated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2099-2106
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• 2006

In this paper, we addressed the node positioning method for minimizing the sensing energy consumption in wireless sensor networks with adjustable sensing ranges. It is necessary for minimizing the sensing energy consumption to minimize the overlapped sensing area by neighboring nodes. To find a optimal node position, we derived a optimal equations by using the overlapped areas, each node's radiuses and expended angles of opposite neighboring nodes. Based on it, we devised a new node positioning method, called as ASRC(Adjustable Sensing Ranges Control). Unlike existing condition based model, our proposed method was derived from mathematical formula, and we confirmed its validity of sensing energy consumption through simulations.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1695-1700
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• 2005

In this paper, we propose an optimal thresholding method for the voxel coloring in the reconstruction of a 3D shape. Our purposed method is a new approach to resolve the trade-off error of the threshold value on determining the photo-consistency in the conventional method. Optimal thresholding value is decided to compare the surface voxel of photo-consistency with inside voxel on the optic ray of the center camera. As iterating the process of the voxels, the threshold value is approached to the optimal value for the individual surface voxel. And also, graph cut method is reduced to the surface noise on eliminating neighboring voxel. To verify the proposed algorithm, we simulated in the virtual and real environment. It is advantaged to speed up and accuracy of a 3D face reconstruction by applying the methods of optimal threshold and graph cut as compare with conventional algorithms.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.72-79
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• 2008

This paper designs a looper-tension controller for mass-flow stabilization in hot strip finishing mills. By Newton's 2nd law and Hooke's law, nonlinear dynamic equations on the looper-tension system are firstly derived, and linearized by a linearization algorithm using a Taylor's series expansion. Moreover, a tension calculation model is obtained from the nonlinear dynamic equations which is called as a soft sensor of strip tension between two neighboring stands. Next, a looper-tension servo controller is designed by an ILQ(Inverse Linear Quadratic optimal control) algorithm, and it is combined with a minimal disturbance observer which to attenuate speed disturbances by AGC and operator interventions, etc.. Finally, it is shown from by a computer simulation that the proposed ILQ controller with a disturbance observer is very effective in stabilizing the strip mass-flow under some disturbances, moreover it has a good command following performance.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.107.5-107
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• 2002

In this paper, a kinematic optimal design of a new paralleltype rolling mill based upon two Stewart platforms manipulator is investigated. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. A manipulability measure, as the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring joints, are optimally designed by maximizing the global manipulability measure in the entire workspace.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.764-775
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• 2002

A kinematic and dynamic optimal design of a new parallel-type rolling mill based upon Stewart platform manipulator is investigated. To provide sufficient degrees-of-freedom in the rolling process and the structural stability of each stand, a parallel manipulator with six legs is considered. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. By splitting the weighted Jacobian matrices Into two parts, the linear velocity, angular velocity, force, and moment transmissivities are analyzed. A manipulability measure, the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring Joints, are optimally designed by maximizing the global manipulability measure in the entire workspace. The maximum force needed in the hydraulic actuator is also calculated using the structure determined through the kinematic analysis and the Plucker coordinates. Simulation results are provided.