• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.15-22
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• 2006

In OFDMA system, even if the number of allocated sub-channel in mobile station varies from one to the whole sub-channel as in base station, while because of mobile station's transmit power is lower than that of base station, therefore full loading range(FLR) constraint occurs where whole sub-channel can be used and the conventional open-loop power control scheme can not be used beyond FLR. We propose a new scheme that limits the maximum sub-channel allocation number and uses power concentration gain(PCG) depending on location of mobile station, which is based on ranging in OFDMA system. Simulation results show that the proposed scheme provides solutions for optimum utilization of radio resource depending on the location of mobile station and enables open-loop power control beyond FLR without extra hardware complexity.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1786-1790
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• 2004

The main objective of this paper is to analyze the performance of various force control algorithms in improving and adjusting the compliance of industrial robots in contact with their environment. Some of fundamental force control algorithms such as sensorless control, impedance control and hybrid position/force control are theoretically analyzed and simulated for various situations of an environment, and then a series of experiments using them were performed. In this paper, a control scheme to use position control in implementing the impedance control was investigated in order to nullify the effect of joint friction. The new reference trajectory is generated using contact force feedback and original desired trajectory. And an inner position control loop is designed to provide accurate position tracking for the new reference trajectory and good disturbance rejection. Experiments to insert a peg in a hole (so-called the peg-in-a-hole task) were performed with HILS (hardware-in-theloop simulation) system based on the results of the analyses and simulations on the characteristics of each control algorithm. The experiments showed that various force control methods improved the performance of robots in close contact with the environment by adjusting their compliance with respect to an arbitrary set of coordinates.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.185-194
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• 2016

It is essential for generating the synthetic image to test and evaluate a guided missile system in the hardware-in-the-loop simulation. In order to make the evaluation results to be more reliable, the extent of fidelity and rendering performance of the synthetic image cannot be left ignored. There are numerous challenges to simulate the LWIR sensor signature of sea surface depending on the incident angle, especially in the maritime environment. In this paper, we investigate the key factors in determining the apparent temperature of sea surface and propose the approximate formula consisting of optical characteristics of sea surface and sky radiance. We find that the greater the incident angle increases, the larger the reflectivity of sea surface, and the greater the water vapor concentration in atmosphere increases, the larger the amount of sky radiance. On the basis of this information, we generate the virtual maritime environment in LWIR region using the SE-WORKBENCH, physically based rendering software. The margin of error is under seven percentage points.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.117-122
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• 1998

The recent developments and studies in the framework of output tracking control in the field of robotics that has been studied in the Control Laboratory, are presented. An output controller based on“Hardware-ln-the-Loop Simulation”(HILS) and“Rapid Control Prototyping”(RCP) concepts is developed using dSPACE. These new concepts are shown to be particularly beneficial for manipulator control tasks. In the Elbow manipulator design, there are two kinds of manipulators, namely the serial-drive type and the parallelogram-drive manipulator, The objective of this research is to model the two Elbow manipulators and to implement the proposed controller for manipulator applications. The control goal is to force the manipulator to follow a given trajectory in the given work space. Output controllers of the two elbow manipulators that are based on the model matching control approach have been implemented in two models that represent the robot equations of motion. To reduce the efforts in evaluating the proposed algorithm, a new system configuration method, based on HILS and RCP tools, was suggested to determine the parameters of the integrated dynamic system.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.88-93
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• 2016

LCL filters are widely used in high-order harmonics attenuation of output currents in grid-connected inverters. However, output currents of grid-connected inverters with LCL filters can become unstable because of the resonance of the filters. Given that the characteristics of output currents in inverters mostly depend on filter performance, the exact analysis of filters by considering parasitic components is necessary for both harmonics attenuation and current control. LCL filters have three or four parasitic components: the series and/or parallel resistance of the filter capacitor and the series resistance of the two filter inductors. Most studies on LCL filters have focused on the parasitic components of the filter capacitor. Although several studies have addressed the parasitic components of the filter inductor at the inverter side, no study has yet investigated the concurrent effects of series resistance in both filter inductors in detail. This paper analyzes LCL filters by considering series resistance in both filter inductors; it proposes an active damping method based on the virtual series resistance of LCL filters. The performance of the proposed active damping is then verified through both simulation and experiment using Hardware-in-the-Loop Simulator(HILS).

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.321-327
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• 2006

The previous paper described the logic tuning, the vehicle manufacture and the evaluation in the HILS system for the purpose of the development of a Steer-By-Wire(SBW) system. This paper describes the content of applying to a new HILS system, the vehicle manufacture and the result of the evaluation performed in Independent-type SBW(I-SBW) system. Here, the SBW indicates the method of steering both tires by using one motor as the steering gear actuator, similar to the conventional steering system. On the other hand, the I-SBW means the method of steering both front tires independently by using dual motors as the steering gear actuator. As a result, the layout and the kinematical mechanism of the I-SBW system are quite different from those of the typical steering mechanism. Nevertheless, there is no change in the steering column motor system. In the report, we first describe the structure and control logic of the I-SBW system, and then the control effect on this system as applied for both the HILS system and a vehicle. Furthermore, our HILS system involves the actuator mechanism which realizes the reaction force of the road surface with a minimized frictional force in operation. Therefore, it is possible for us to tune the control logic via the HILS system and confirm the effect of the tuned control logic by applying it to a vehicle with the I-SBW system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2228-2234
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• 2000

Steering of the vehicles on a slippery highway is a difficult task for most passenger car drivers. The steering vehicles on slippery roads tend to slide outward with less lateral forces than on nor mal roads. When the drivers notice that their vehicles on a slippery highway start to depart from the cornering lane, most of them make a sudden steering and/or braking, which in turn may induce spin-out and instability on their vehicles. In this paper, an active steering control method is proposed such that the vehicles in slippery roads are steered as if they are driven on the normal roads. In the proposed method, the estimated lateral forces acting on the steering tires are compared with the reference values and the difference is compensated by the active steering method. A fuzzy logic controller is designed for this purpose and evaluated on a steering Hardware-In-the-Loop Simulation (HILS) system. Steering performance results on the slippery curved and sinus roads demonstrate the effectiveness of the proposed controller. This method can be realized with the steer-by-wire concept and is promising as an active safety technology.

• Journal of Applied Reliability
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• v.16 no.3
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• pp.208-215
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• 2016

Purpose: ASRP for the domestic development guided missiles requires not only for the reliability evaluation of the products in storage but also for the life cycle management of the products including development prototypes and initial production items. Methods: For this purpose, it should be performed to build a performance database before and after the accelerated aging test with shelf life items including development prototypes and initial production items, based on which the lifetime prediction should also be carried out. In addition, HILS must be applied for the acceptance test with the initial and follow-up production items, and also for ASRP for the long-term storage products in order to secure systematic quality assurance. Results: The results for the life cycle reliability Improving of domestic development of guided missiles are DB building of prescription Item performance, active application of HILS, Management associated with guided missiles life cycle and to Secure technology data about the introduction of foreign guided missiles. Conclusion: Furthermore, it is demanded that DTaQ, the managing agency of ASRP, actively take part in the process to maintain reliability engagement consistency over the life cycle of guided missiles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.708-717
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• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.180-183
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• 2005

The engine mount of vehicle systems is role of support engine mass and isolate noise and vibration from engine disturbance forces. One of attractive candidates to achieve this goai is to utilize a semi-active ER engine mount. By applying this, we can effectively control damping force and hence the noise and vibration by just controlling the intensity of electric field. However, control performance of the engine mount may be very sensitive to temperature variation during engine operation. In this work, we Investigate dynamic performances of ER engine mount with respect to the temperature variation. In order to undertake this, a flow-mode type of ER engine mount is designed and manufactured. Displacement transmissibility is experimentally and numerically evaluated as a function of the electric field. The ER engine mount is then incorporated with full-vehicle model in order to investigate vibration control performance. After formulating the governing equation of motion, a semi-active controller is designed. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at various engine speeds are evaluated in the frequency and time domains.