• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.300-304
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• 2015

This paper presents an omnidirectionally beam-steerable orthogonal loop resonator for wireless power transfer. The resonator is composed of two orthogonal loops. These connections of two loops and the current direction on the loops are determined by the control of switch. The magnetic field direction is determined by the vector sum of each loop current. The beam is steerable to eight directions by four switch modes. Using the suitable switch mode, the simulation and measurement efficiencies in the whole azimuthal direction are 56.3~60.0 %(deviation 3.7 %) and 41.2~48.7 %(deviation 7.5 %), respectively. The results show a little variation of transmission efficiency in the azimuthal direction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1322-1333
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• 2014

To track the sinusoidal current under stationary frame and suppress the effects of low-order grid harmonics, the multi-resonant quasi-proportional plus resonant (PR) controller has been extensively used for digitally controlled LCL-type pulse-width modulation (PWM) converters with capacitor-current-feedback active damping. However, designing the controller is difficult because of its high order and large number of parameters. Moreover, the computation and PWM delays of the digitally controlled system significantly affect damping performance. In this study, the delay effect is analyzed by using the Nyquist diagrams and the system stability constraint condition can be obtained based on the Nyquist stability criterion. Moreover, impact analysis of the control parameters on the current loop performance, that is, steady-state error and stability margin, identifies that different control parameters play different decisive roles in current loop performance. Based on the analysis, a simplified controller design method based on the system specifications is proposed. Following the method, two design examples are given, and the experimental results verify the practicability and feasibility of the proposed design method.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.448-451
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• 2004

MSC (Multi-Spectral Camera) system is an electro-optical camera system which is being developed to be installed on KOMPSAT-2 satellite. High resolution image data from MSC system will be transmitted to the ground-station through x-band antenna called APS (Antenna Pointing System). APS is a directional antenna which will point to the receiving antenna at ground station while the satellite is passing over it. The APS needs to be controlled accurately to provide the reliable communication with big RF link margin. The APS is controlled by ATS (Antenna Tracking Software) which is included in the MSC software. ATS uses the closed loop control algorithm which will use TPF (Tracking Parameter File) as an input for antenna position, and will use two resolve readings from APS as a feedback. ATS has been developed and verified using APS QM (Qualification Model) and all the control parameters for ATS have been tested and verified. Various kinds of maximum, nominal and realistic dynamics for the APS movement have been simulated and verified. In this paper, closed loop servo control algorithm and obtained APS position error from the verification test with APS QM will be presented in detail

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.794-797
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• 1988

G. Binnig and H. Rohrer introduced the Scanning Tunneling Microscope (STM) in 1982 and developed it into a powerful and not to be missed physical tool. Scanning tunneling Microscopy is a real space surface imaging method with the atomic or subatomic resolution in all three dimensions. The tip is scanned over the surface by two piezo translators mounted parallel (X-piezo and Y-piezo) to the surface and perpendicular to each other. The voltage applied to the third piezo (Z-piezo) translator mounted perpendicular to the surface to maintain the tunneling current through the gap at a constant level reflects then the topography of the surface. The feed back control loop for the constant gap current is designed using the automatic control technique. In the designing process of the feed back loop, the identification of the gap dynamics is very complex and has difficulty. In this research, using some suitable test signals, the system dynamics of the gap including the Z-piezo are investigated. Especially, in this paper, a system model is proposed for the gap and Z-piezo series system. Indicial response is used to find out the model. The driving voltage of the Z-piezo and the tunneling current are considered as input and output signals respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.2
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• pp.63-68
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• 2017

This paper proposes a new non-isolated DC conversion circuit topology of the voltage source coupled inductor series resonant high-frequency PFM controlled boost chopper type DC-DC power converter using two in one IGBT power module, which can efficiently operate under a principle of zero current soft switching for wide output regulation voltage setting ranges and wide fluctuation of the input DC side voltage as well as the load variation ranges. Its steady state operating principle and the output voltage regulation characteristics in the open-loop-based output voltage control scheme without PI controller loop are described and evaluated from theoretical and experimented viewpoints. Finally, in this paper the computer-aided simulation steady-state analysis and the experimental results are presented in order to prove the effectiveness and the validity of voltage regulation characteristics of the proposed series resonant zero current soft switching boost chopper type DC-DC power converter circuit using IGBTs which is based on simple pulse frequency modulation strategy more than, 20kHz.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.71-81
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• 2000

This paper describers a look ahead algorithm of PC-NC(personal computer numerical control). The algorithm is based on acceleration/deceleration before interpolation which doesn\`t include a command error and determines a feedrate value at the end point of each block(or start point of each block). The algorithm is represented as following; 1) calculating two maximum arrival feedrates(F$_1$,F$_2$) by an acceleration value, a command feedrate, and the distance of a NC block, 2) getting a tangent feedrate (F$_3$) of the adjacent blocks, 3) choosing a minimum value among these three feedrates, and 4) setting the value to a feedrate of a start point of the next block(or a end point of the previous block). The proposed look ahead algorithm was implemented and tested by using a commercial TROS(real time operation system) on the MS-Windows NT 4.0 in a PC platform. For interfacing to a machine, a counter board, a DAC board and a DIO board were used. The result of the algorithm increased a machining precision and a machining speed in many short blocks.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.121-128
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• 2006

This paper deals with the application of enhanced perturbation estimation (SMCEPE) to sliding mode control of a dynamic system in the presence of perturbations including external disturbances, unpredictable parameter variations, and unstructured dynamics. Compared to conventional sliding mode control (SMC) and sliding mode control with perturbation estimation (SMCPE), the proposed one can offer robust control performances under serious control conditions, such as fast dynamic perturbations and slow loop-closure speeds, without a priori knowledge on upper bounds of perturbations. The perturbation estimator in SHCEPE also has more adaptability owing to the fractional-order hold technique. The effectiveness and superiority of the proposed control strategy are demonstrated by a series of simulations on the position tracking control of a two-link robot manipulator.

• Smart Structures and Systems
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• v.14 no.4
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• pp.643-658
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• 2014

This paper presents the design, modelling and, simulation and experimental results of a shape memory alloy (SMA) actuator based critical motion control application. Dynamic performance of SMA and its ability in replacing servo motor is studied for which the famous open loop unstable balancing ball and beam system direct driven by antagonistic SMA is designed and developed. Simulation uses the mathematical model of ball and beam structure derived from the first principles and model estimated for the SMA actuator by system identification. A PID based cascade control system consisting of two loops is designed and control of ball trajectory for various target positions with settling time as control parameter is verified experimentally. The results demonstrate the performance of SMA for a complicated i.e., under actuated, highly nonlinear unstable system, and thereby it's dynamic behaviour. Control strategies bring out the effectiveness of the actuator and its possible application to much more complex applications such as in aerospace control and robotics.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.177-185
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• 2003

Current issues of receding horizon control scheme are reviewed. The basic idea of receding horizon control is presented first. For unconstrained and constrained systems, the results of closed-loop stability in receding horizon control are surveyed. We investigate the two categories of robustness of receding horizon control : stability robustness and performance robustness. The existing optimization algorithm to solve receding horizon control problem is briefly mentioned. It is shown that receding horizon control has been extended to nonlinear systems without losing good properties such as stability and robustness. Many industrial applications are reported along with extensive references related to receding horizon control.