• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 춘계학술대회논문집
• /
• pp.554-558
• /
• 2002

A magnetostrictive sensor is used to measure stress waves propagating in a ferromagnetic cylinder without physical contact. The performance of a magnetostrictive sensor is affected most significantly by the bias magnetic field applied around the measurement location. The goal of this paper is to carry out the topology optimization of the bias magnet and yoke assembly to maximize the sensor output for traveling bending waves. We will use the multi-resolution topology optimization strategy to find the assembly of the bias magnet and the yoke that is easy to realize. The effectiveness of the present design is confirmed by an actual measurement of the sensor signal with the proposed bias magnet and yoke configuration.

• 로봇학회논문지
• /
• 제7권3호
• /
• pp.205-215
• /
• 2012

A GPS sensor is widely used in many areas such as navigation, or air traffic control. Particularly, the car navigation system is equipped with GPS sensor for locational information. However, when a car goes through a tunnel, forest, or built-up area, GPS receiver cannot get the enough number of satellite signals. In these situations, a GPS receiver does not reliably work. A GPS error can be formulated by sum of bias error and sensor noise. The bias error is generated by the geometric arrangement of satellites and sensor noise error is generated by the corrupted signal noise of receiver. To enhance GPS sensor accuracy, these two kinds of errors have to be removed. In this research, we make the road database which includes Road Database File (RDF). RDF includes road information such as road connection, road condition, coordinates of roads, lanes, and stop lines. Among the information, we use the stop line coordinates as a feature point to correct the GPS bias error. If the relative distance and angle of a stop line from a car are detected and the detected stop line can be associated with one of the stop lines in the database, we can measure the bias error and correct the car's location. To remove the other GPS error, sensor noise, the Kalman filter algorithm is used. Additionally, using the RDF, we can get the information of the road where the car belongs. It can be used to help the GPS correction algorithm or to give useful information to users.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.336-339
• /
• 2007

A sensor having capability to measure two different kinds of ultrasonic waves selectively is described. Under the same bias field configuration, this magnetostrictive type sensor can selectively measure longitudinal waves and flexural ones. Since the switching operation of mode selection is made only by changing the polarity of the permanent magnets used to configure the bias field, it will be very useful after the permanent magnet are interchanged with electromagnets. In order to find the optimal operating bias field, finite elements analysis is used and the condition for flexural wave measurements to meet is found. The linearity of the sensor is verified by experiments and the requirements for linearity also are proposed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1325-1328
• /
• 2007

When we visualize the sound field radiated from a spherical sound source, spherical acoustic holography is proper among acoustic holography methods. However, there are measurement errors due to sensor position mismatch, sensor mismatch, directivity of sensor, and background noise. These errors are amplified if one predicts the pressures close to the sources: backward prediction. The goal of this paper is to quantitatively examine the effects of the error due to sensor position mismatch on acoustic pressure estimation. This paper deals with the cases of which the measurement deviations are distributed irregularly on the hologram plane. In such cases, one can assume that the measurement is a sample of many measurement events, and the cause of the measurement error is white noise on the hologram plane. Then the bias and random error are derived mathematically. In the results, it is found that the random error is important in the backward prediction. The relationship between the random error amplification ratio and the measurement parameters is derived quantitatively in terms of their energies.

• International Journal of Internet, Broadcasting and Communication
• /
• 제12권3호
• /
• pp.95-101
• /
• 2020

We studied the Implementation and design of inertial sensor that enables to improve performance by reduce the noise of rotor which Angle of inclination. Analyze model equation including motion equation and error, signal processing filter algorithm on high frequency bandwidth with eliminates error using estimation of error coefficient method is was designed and the prototype inertial sensor showed the pick off noise up to 0.2 mV and bias error performance of about 0.06 deg/hr by the experiments. Accordingly, we confirmed that the design of inertial sensor was valid for high rotation.

• 항공우주시스템공학회지
• /
• 제7권1호
• /
• pp.8-18
• /
• 2013

Recently, the advanced condition monitoring methods such as the model-based method and the artificial intelligent method have been applied to maximize the availability as well as to minimize the maintenance cost of the aircraft gas turbines. Among them the non-linear GPA(Gas Path Analysis) method and the GA(Genetic Algorithms) have lots of advantages to diagnose the engines compared to other advanced condition monitoring methods such as the linear GPA, fuzzy logic and neural networks. Therefore this work applies both the non-linear GPA and the GA to diagnose AE3007 turbofan engine for an aircraft, and in case of having sensor noise and bias it is confirmed that the GA is better than the GPA through the comparison of two methods.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2002년도 ICCAS
• /
• pp.86.5-86
• /
• 2002

The measurement sensor may contain unknown bias in addition to the white noise in the measurement sequence. In this paper, fault detection and diagnosis scheme for the measurement sensor is developed based on the adaptive estimator. The proposed scheme consists of a parallel bank of Kalman-type filters each matched to a set of different possible biases, a mode probability evaluator, an estimate combiner at the outputs of the filters, a bias estimator, and a fault detection and diagnosis logic. Monte Carlo simulations for the PWR steam generator in the nuclear power plant are provided to illustrate the effectiveness of the proposed scheme.

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

• International Journal of Aeronautical and Space Sciences
• /
• 제1권1호
• /
• pp.70-80
• /
• 2000

The attitude knowledge error model is formulated for specifically KOMPSAT attitude determination system using the Lefferts/Markley/Shuster method, and the attitude determination(AD) error analysis is performed so as to investgate the on-board attitude determination capability of KOrea Multi-Purpose SATellite(KOMPSAT) using the covariance analysis method. Analysis results show there is almost no initial value effect on Attitude Determination (AD) error and the sensor noise effects on AD error are drastically decreased as is predicted because of the inherent characteristic of Kalman filter structure. However, it shows that the earth radiance effect of IR-sensor(earth sensor) and the bias effects of both IR-sensor and fine sun sensor are the dominant factors degrading AD error and gyro rate bias estimate error in AD system. Analysis results show that the attitude determination errors of roll, pitch and yaw axes are 0.056, 0.092 and 0.093 degrees, respectively. These numbers are smaller than the required values for the normal mission of KOMPSAT. Also, the selected on-orbit data of KOMPSAT is presented to demonstrate the designed AD system.

• 센서학회지
• /
• 제27권6호
• /
• pp.362-367
• /
• 2018

A complementary metal oxide semiconductor (CMOS) binary image sensor is proposed for low-power and low-noise operation. The proposed binary image sensor has the advantages of reduced power consumption and fixed pattern noise (FPN). A gate/body-tied (GBT) p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET)-type photodetector is used as the proposed CMOS binary image sensor. The GBT PMOSFET-type photodetector has a floating gate that amplifies the photocurrent generated by incident light. Therefore, the sensitivity of the GBT PMOSFET-type photodetector is higher than that of other photodetectors. The proposed CMOS binary image sensor consists of a pixel array with $394(H){\times}250(V)$ pixels, scanners, bias circuits, and column parallel readout circuits for binary image processing. The proposed CMOS binary image sensor was analyzed by simulation. Using the dynamic comparator, a power consumption reduction of approximately 99.7% was achieved, and this performance was verified by the simulation by comparing the results with those of a two-stage comparator. Also, it was confirmed using simulation that the FPN of the proposed CMOS binary image sensor was successfully reduced by use of the double sampling process.