• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.115-122
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• 2011

Adaptive arrays suffer from severe performance degradation when there are errors in the steering vector. The DCRCB (doubly constrained robust Capon beamformer) overcomes such a problem, introducing a spherical uncertainty set of the steering vector together with a norm constraint. However, in the standard DCRCB, it is a difficult task to determine the bound for the uncertainty, the radius of the spherical set, such that a near best solution is obtained. A novel beamforming method is presented which has no difficulty of the uncertainty bound setting, employing a recursive search for the steering vector. Though the basic idea of recursive search has been known, the conventional recursive method needs to set a parameter for the termination of the search. The proposed method terminates it by using distances to the signal subspace, without the need for parameter setting. Simulation demonstrates that the proposed method has better performance than the conventional recursive method and than the non-recursive standard DCRCB, even the one with the optimum uncertainty bound.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.483-487
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• 1994

In this paper, we analize the effect of a steering water used in a unified phase I-phase II semi-infinite constrained optimization algorithm and present a new algorithm based on the facts that when the point x is far away from the feasible region where all the constraints are satisfied, reaching to the feasible region is more important than minimizing the cost function and that when the point x is near the region, it is more efficient to try to reach the feasible region and to minimize the cost function concurrently. Also, the angle between the search direction vector and the gradient of the cost function is considered when the steering parameter value is computed. Even though changing the steering parameter does not change the rate of convergence of the algorithm, we show through some examples that the proposed algorithm performs better than the other algorithms.

• Journal of Magnetics
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• v.17 no.4
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• pp.285-290
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• 2012

Electric Power Steering (EPS) system is superior to conventional Hydraulic Power Steering (HPS) system in aspect of fuel economy and environmental concerns. The EPS system consists of torque sensor, electric motor, ECU (Electric Control Unit), gears and etc. Among the elements, the torque sensor is one of the core technologies of which output signal is used for main input of EPS controller. Usually, the torque sensor has used torsion bar to transform torsion angle into torque and needs linear characteristic in terms of flux variation with respect to rotation angle of permanent magnet. The torsion angle of both ends of a torsion bar is measured by a contact variable resistor. In this paper, the sensor is accurately analyzed using 3D finite element method and its characteristics with respect to four different shapes of the stator teeth are compared. The four shapes are rectangular, triangular, trapezoidal and circular type.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.113-119
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• 2015

The technical development of electric vehicles has been actively proceeding because of the reduction of oil resources and need for eco-friendly vehicle technology. In particular, an electronic control unit is an important element in the technology of electric vehicles due to the motor drive system. This paper concerns an experimental study on the thermal analysis of the steering control ECU structure for an electric vehicle. The ECU unit is designed for eight heat sinks for the thermal analysis of the ECU structure. The thermal analysis characteristics of the ECU structure are evaluated by the temperature distribution, heat flow, von Mises stress, total translation, and external surface temperature measurement of the ECU unit.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.162-167
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• 2004

In this research the Co-simulation technique for an electric power steering system with MATLAB/SIMULINK and a full vehicle model with ADAMS has been developed. The dynamic responses of vehicle chassis and steering system are evaluated. Then, a full vehicle model interacted with EPS control is concurrently simulated with an impulsive steering wheel torque input to analyze the stability of 'free control' or hands free motion for Sports Utility Vehicle. This integrated method allows engineers to reduce the prototype testing cost and to shorten the developing period.

• Transactions on Electrical and Electronic Materials
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• v.10 no.2
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• pp.44-48
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• 2009

A simulation study of a 10-bit two-stage DAC was done by using a conventional current switch cell. The DAC adopts the segmented architecture in order to reduce the circuit complexity and the die area. The 10-bit CMOS DAC was designed in 2 blocks, a unary cell matrix for 6 MSBs and a binary weighted array for 4 LSBs, for fabrication in a 0.35-${\mu}m$ CMOS process. To cancel the accumulation of errors in each current cell, a symmetrical switching sequence is applied in the unary cell matrix for 6 MSBs. To ensure high-speed operation, a decoding circuit with one stage latch and a cascode current source were developed. Simulations show that the maximum power consumption of the 10-bit DAC is 74 mW with a sampling frequency of 100 MHz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.511-514
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• 2005

This paper propose an advanced control strategy to improve vehicle handling and directional stability by integrating Active Front Steering(AFS) with Electronic Stability Program(ESP) . The effect of the integrated control system on the vehicle handling characteristics and directional stability is studied through a close loop computer simulation of and eight degree of freedom nonlinear vehicle model and driver model. Simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and directional stability

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1126-1131
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• 2007

This paper presents unified chassis control (UCC) to improve the vehicle lateral stability. The unified chassis control implies combined control of active front steering (AFS), electronic stability control (ESC) and continuous damping control (CDC). A direct yaw moment controller based on a 2-D bicycle model is designed by using sliding mode control law. A direct roll moment controller based on a 2-D roll model is designed. The computed direct yaw moment and the direct roll moment are generated by AFS, ESP and CDC control modules respectively. A control authority of the AFS and the ESC is determined by tire slip angle. Computer simulation is conducted to evaluate the proposed integrated chassis controller by using the Matlab, simulink and the validated vehicle simulator. From the simulation results, it is shown that the proposed unified chassis control can provide with improved performance over the modular chassis control.

• Journal of Auto-vehicle Safety Association
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• v.7 no.2
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• pp.32-38
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• 2015

A sine with dwell test is well known as a test scenario for evaluation of performance of electronic stability control(ESC) on passenger vehicles and heavy commercial vehicles. However, when it comes to ESC for medium commercial vehicles, the test scenario has not been established yet. In this paper, the sine with dwell test was modified considering characteristics of medium commercial vehicles. The three main modifications of the original test scenario are the steering angle level, steering frequency, and loading condition of the vehicle. These modifications are derived from simulation study for different medium commercial vehicles. From simulation study, it was shown that the ESC system for medium commercial vehicle is objectively evaluated by the proposed test scenario. A clear improvement on vehicle stability was seen in the results when ESC system was used.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.129-135
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• 2011

In this paper, we propose a multi target's elevation angle estimation method using multi beam forming technique. This method make a stacked beam to digital processing a received signal in array element. There can be desired receiving beam to application weight value at antenna element in beam forming. Currently, we are to make multi stacked beam using fast fourier transform in stead of phase shifter to be a computer performance much improvement. Also, we improve multi beam directivity using beam steering error correction technique in order to beam steering to desired direction in receiver. Through simulation, we show that the proposed elevation estimation method based on fast fourier transform and beam steering error correction technique, improves th performance of target estimation compared to previous method.