• Journal of Positioning, Navigation, and Timing
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• 제9권4호
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• pp.379-385
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• 2020

The satellite employs an adaptive beamformer to efficiently detect various signals and to suppress multiple interference signals, simultaneously. Although the adaptive beamforming satellite system needs Angle-of-Arrival (AOA) information of the desired signal, it is difficult to estimate the signal AOAs on the satellite environment. However, the AOA estimation on the ground control tower is more efficient and accurate comparing to the satellite environment. In this paper, we propose an adaptive beamforming satellite system based on the signal location information on the ground, consisting on an angle estimator, an adaptive beamformer, and signal processing & D/B unit. The ground control tower estimates the accurate location of the signal source, and it sends the estimated coordinates of the desired signal to the satellite. The angle estimator mounted on the satellite calculates the desired signal AOA, based on the signal location information transmitted from the ground control center. The satellite beamformer detects the desired signal and suppresses unwanted signals based on the signal AOA calculated by the angle estimator. We provide computer simulation results to present the performance of the proposed satellite adaptive beamforming system based on the signal location information.

• 전력전자학회논문지
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• 제26권4호
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• pp.298-301
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• 2021

A mechanical angle estimator is presented in this study to achieve the sensorless control of permanent magnet synchronous motor (PMSM) used in driving a reciprocating compressor. Braking the PMSM at a specific mechanical angular position is critical for the silent stoppage of the reciprocating compressor. The performance of conventional mechanical angle observers used in reciprocating compressor drives can be seriously affected according to gains of the speed controller because such observers rely on the magnitude of current ripples. A speed ripple-based mechanical angle estimator is proposed to solve this problem. Experimental results showed the effectiveness of the proposed method.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.38-46
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• 2011

This paper presents roll angle estimator which used Kalman filter. Recently, the uses of the ELSD (Electronic Limited Slip Differential) and TVD(Torque Vectoring Differential) for vehicle yaw control are studied in many researches. However the roll angle can be negative effect of ELSD and TVD control. Therefore the information of roll angle can be used for vehicle yaw control. Moreover it can be used for rollover prevent control. Recently, most of the vehicles use lateral acceleration and yaw rate sensor. In this paper, design of Kalman filter which used lateral acceleration and yaw rate information is developed. In this paper, in order to verify the estimator ability, the CarSim and Matlab/Simulink are used.

• 대한조선학회논문집
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• 제61권2호
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• pp.98-105
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• 2024

Due to the low accuracy of measured data obtained from low-cost GNSS and IMU devices, it was hard to secure the required accuracy of the measured position and heading angle for autonomous navigation which was conducted by a model-scale marine mobility. In this paper, a localization technique using the Extended Kalman Filter (EKF) is proposed for coping with the issue. First of all, a position and heading angle estimator is developed using EKF with the assumption of a point mass model. Second, the measured data from GNSS and IMU, including position, heading angle, and velocity are used for the estimator. In addition, the heading angle is additionally obtained by comparing the LiDAR point cloud with map information for a temporal water tank. The newly acquired heading angle is integrated into the estimator as an additional measurement to correct the inaccuracy in the heading angle measured from the IMU. The effectiveness of the proposed approach is investigated using data acquired from preliminary tests of the model-scale autonomous marine mobility.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.176-184
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• 2001

The VDC(Vehicle Dynamics Control) is a control system whose target is to improve vehicle stability under critical motion. The system has a good potential of becoming a standard active safety unit in passenger vehicles since it can be implemented on top of the ABS/TCS system with little extra cost. This, however, is possible only when the signals that the VDC system demands can be obtained with sufficient accuracy. In this research, estimators for the road friction coefficient and body sideslip angle have been designed. The two variables have great influence upon performance of the VDC system but not directly measurable. For the estimator design, the Newton method and the nonlinear observer theory have been exploited. The performance of the estimator have been verified via simulations on critical driving conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1103-1108
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• 2007

This paper describes a robust model-based roll state estimator for application to the detection of impending vehicle rollover. The roll state estimator is based on a 2-D bicycle model and a roll model to estimate the maneuver-induced vehicle roll motion. The measurement signals are lateral acceleration, yaw rate, steering angle, and vehicle speed. Vehicle mass is adapted to obtain robust performance of the estimator. Computer simulation is conducted to evaluate the proposed roll state estimator by using a validated vehicle simulator. It is shown that the roll state estimator shows robust performance without exact vehicle mass information.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.194.1-194.1
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• 2005

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.278-281
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• 2000

In this abstract a novel control scheme of voltage-source PWM rectifiers using only dc-side sensors is proposed. The phase currents are reconstructed from switching states of the rectifier and the dc output current. For effective current control the currents are estimated by a predictive state observer. Also both the phase angle and the magnitude of th source voltage are estimated by phase estimator and magnitude estimator respectively. The validity of the proposed ac sensorless technique is verified by experimental results.

• Journal of Hydrospace Technology
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• 제1권1호
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• pp.75-88
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• 1995

Auto-Pilot System uses heading angle information via the position sensor and the rudder device to control the ship's direction. Most of the control logics are composed of the state estimation and control algorithms assuming that the measurement device and the actuator have no fault except the measurement noise. But such asumptions could bring the danger in real situation. For example, if the heading angle measuring device is out of order the control action based on those false position information could bring serious safety problem. In this study, the control system including improved method for processing the position information is applied to the Auto-Pilot System. To show the difference between general state estimator and F.D.F., BJDFs for the sensor and the actuator failure detection are designed and the performance are tested. And it is shown that bias error in sensor could be detected by state-augmented estimator. So the residual confined in the 2-dimension in the presence of the sensor failure could be unidirectional in output space and bias sensor error is much easier to be detected.

• 한국지능시스템학회논문지
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• 제21권3호
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• pp.283-289
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• 2011

본 논문에서는 차륜형 역진자에 적용되는 속도 추정기 기반 제어기 설계와 다양한 수치 시뮬레이션이 수행되었다. 차륜형 역진자는 불안정한 평형점과 안정한 평형점을 동시에 갖는다. 불안정한 평형점에 대하여 평형을 유지하기 위하여 차륜형 역진자는 지속적으로 제어되어야 한다. 제어기의 입력으로 차륜형 역진자 몸체의 각도, 각속도, 변위 속도 등이 필요하다. 필요한 속도는 모터에 부착된 에코더 신호를 차분하여 얻어지며, 엔코더의 해상도에 민감하게 의존한다. 저해상도 엔코더와 속도 추정기에 기반하여 개선된 속도 검출법이 제안되고 경사면에서 유효함을 보이기 위해서 다양한 수치 시뮬레이션이 수행되었다.