• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.992-997
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• 2009

This paper focuses on the calculation of the missile angular velocity under the reduced sensor condition and its verification using the Flight Motion Simulator(FMS). The missile angular velocity is usually measured by the body gyroscopes, but we assume that the inertial sensors on the missile body are in the absence of pitch and yaw gyroscopes. Under this reduced sensor condition, this paper shows the missile angular velocity can be calculated by using the gimbal seeker gyroscope, the roll body gyroscope, the gimbal angle and its rate. The FMS experiment was carried out to verify the proposed algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.1
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• pp.42-47
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• 2010

This paper considers a fault tolerant control problem for a spacecraft using wheels which are momentum exchanging devices. The control of a satellite with only two healthy wheels has been studied and its result has been presented. Two different configurations have been considered. When the yaw rate cannot be controlled directly by any control input, the desired yaw rate can be obtained by using the roll rate as a pseudo control. As a result, all three angular speeds have been stabilized, and two attitude angles including pitch and yaw have been controlled to converge to the desired values.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.227-234
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• 2008

The purpose of this study was to investigate kinematic factors affecting scores of Olympic Round Game during follow through which was basic and important in archery. For this study, 8 male archers($20{\pm}1\;yrs$, $77{\pm}13kg$, $178{\pm}5\;cm$) of K university participated in the experiment. The seven infrared cameras (Qualisys MCU-240) were used to acquire raw data, and analyzed with Matlab6.5 for variables. The results were as follows: First, angular average velocity of shoulder joint affecting scores was a statistical significance (p=.65, p<.10), and the regression equation was y = - 0.0637 x + 17.074, and determinant coefficient $R^2$ = 0.874 respectively. Second, good records was acquired about $120^{\circ}$/sec. of angular average velocity of shoulder joint. Third, as records was lower and lower, a peak-pulse on angular average velocity of shoulder joint was great during follow through. In conclusion, the record was greater as angular average velocity of shoulder joint was smaller and smaller from $110^{\circ}$/sec. to $160^{\circ}$/sec. It is suggested that a lower angular average velocity of shoulder joint and no peak-pulse may obtain good scores during follow through.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.95-102
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• 2016

Geomagnetic sensors are widely utilized for sensing heading direction of quadrotors. However, measurement from a geomagnetic sensor is easily corrupted by environmental magnetic field interference and roll/pitch directional motion. In this paper, a measurement method of a quadrotor heading direction is proposed for application to yaw attitude control. In order to eliminate roll/pitch directional motion effect, the geomagnetic sensor data is compensated using the roll/pitch angles measured for stabilization control. In addition, yaw-directional angular velocity data from a gyroscope sensor is fused with the geomagnetic sensor data using a complementary filter which is a simple and intuitive sensor fusion method. The proposed method is applied to experiments, and the results are presented to prove validity and effectiveness of the proposed method.

• Journal of Auto-vehicle Safety Association
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• v.14 no.4
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• pp.16-20
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• 2022

Accurate state estimation is important for autonomous driving. However, the estimation error increases in situations that a lot of longitudinal slip occurs. Therefore, this paper presents a vehicle state estimation method using an Extended Kalman Filter. The filter estimates the states of the host vehicle robust to wheel slip. It utilizes the measurements of the four-wheel rotational speeds, longitudinal acceleration, yaw-rate, and steering wheel angle. Nonlinear measurement model is represented by Ackermann Model. The main advantage of this approach is the accurate estimation of yaw rate due to the measurement of the steering wheel angle. The proposed algorithm is verified in scenarios of autonomous emergency braking (AEB), lane change (LC), lane keeping (LK) using an automated vehicle. The results show that the proposed algorithm guarantees accurate estimation in such scenarios.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.197-204
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• 2003

This paper develops a computer model for estimating the handling of a cabover type large-sized truck. The truck is composed of front and rear suspension systems, a frame, a cab, and ten tires. The computer model is developed using ADAMS. A shock absorber, a rubber bush, and a leaf spring aunt a lot on the dynamic characteristic of the vehicle. Their stiffness and damping coefficient are measured and used as input data of the computer model. Leaf springs in the front and rear suspension systems are modeled by dividing them three links and joining them with joints. To improve the reliability of the developed computer model, the frame is considered as a flexible body. Thus, the frame is modeled by finite elements using MSC/PATRAN. A mode analysis is performed with the frame model using MSC/NASTRAN in order to link the frame model to the computer model. To verify the reliability of the developed computer model, a double lane change test is performed with an actual vehicle. In the double lane change, lateral acceleration, yaw rate, and roll angle are measured. Those test results are compared with the simulation results.

• Geophysics and Geophysical Exploration
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• v.23 no.4
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• pp.243-252
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• 2020

To share an understanding of trajectory measurement in surveys using borehole, this tutorial summarizes the relevant mathematical principles of the borehole deviation survey based on coordinate transform. For uncased or open holes, calculations of the azimuth-deviation-tool face rotation using three-component accelerometer and magnetometer measurements are summarized. For the steel-cased holes, calculations are based on the time-derivative formula of the coordinate transform matrix; yaw-pitch-roll angles through time are mathematically determined by integrating the threecomponent angular velocity measurements from the gyroscope while also removing the Earth's rotation effect. Sensor and data fusion to increase the accuracy of borehole deviation survey is explained with an example of the method. These principles of borehole deviation surveys can be adapted for attitude estimation in air-borne surveys or for positioning in tunnels where global positioning system (GPS) signals cannot be accessed. Information on the optimization filter that must be incorporated in sensor fusion is introduced to help future research.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.4
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• pp.171-178
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• 2021

Caravans are easily affected by external physical factors and often cause dangerous situations for passengers. Therefore, in order to secure the stability of the passenger, there is a need to develop a sway reduction device capable of preventing the sway phenomenon in advance. This paper aims to minimize the hitch angle between the tow vehicle and the caravan. Specifically, the initial instability of the caravan is detected through an IMU sensor mounted on each of the tow vehicle and the caravan, and a control value is calculated to reduce errors from the Hitch angle and Hitch yaw rate using a PID controller. Different braking torques are generated, distributed, and controlled on the left and right brakes of the caravan according to the calculated control value. It could be verified through the driving experiment that the hitch angle was decreased compared to the case where the performance of the sway reduction device was not controlled, and the transverse stability improvement rate was improved by 94.49% compared to before control.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.20-28
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• 2005

This paper addresses uncertainty issues encountered recently in measuring head vibration using the conventional 6-axis or 9-axis bite-bar model. Those conventional bite-bar models are shown to present insufficient information to evaluate a generalized motion of head vibration. In order to overcome such limit, a new theoretical measurement model that consists of four 3-axis linear accelerometers is suggested. It is shown to enable the measurement of three angular acceleration components and six second-order angular velocity-dependent terms. Those nine angular motion-related ones, in addition to the three linear acceleration terms at the origin, are found to make it possible to evaluate the generalized head vibration for a given position. To examine the feasibility of the proposed method, a newly designed 12-axis bite-bar was developed. Detailed experimental results obtained from the developed 12-axis bite-bar are demonstrated in this paper. They illustrate that the popular 6-axis bite-bar model yield about $4.0\%$ relative measurement uncertainty for the pitch component of head vibration, $14\%$ and $10\%$ relative measurement uncertainty for the roll and yaw components of head vibration, respectively. Furthermore, this paper proposes other uncertainty factors to be considered in the future.