• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.54-58
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• 1989

The purpose of this paper is to develop a more accurate attitude algorithm with low grade gyro output. The proposed algorithm estimates attitudes by combining accelerometer and gyro output. For performance improvement of the algorithm, a method of velocity compensation is proposed for a better attitude estimation which is calculated from the accelerometer output. Velocity compensation is done by using Kalman Filter to estimate another velocity component.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 추계학술발표회 논문집
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• pp.117-121
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• 2004

In this paper, the error compensation method of the low-cost IMU is proposed. In general, the position and attitude error calculated by accelerometers and gyros grows with time. Therefore the additional information is required to compensate the drift. The attitude angles can be bound accelerometer mixing algorithm and the heading angle can be aided by single antenna GPS velocity. The Kalman filter is used for error compensation. The result is verified by comparing with the attitude calculated and dynamics position determination by Attitude Heading Reference System with Micro Electro Mechanical System for a basis

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2120-2125
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• 2005

The principal idea of vibration isolation is to filter out the response of the system over the corner frequency. The isolation objectives are to transmit the attitude control torque within the bandwidth of the attitude control system and to filter all the high frequency components coming from vibration equipment above the bandwidth. However, when a reaction wheels or control momentum gyros control spacecraft attitude, vibration inevitably occurs and degrades the performance of sensitive devices. Therefore, vibration should be controlled or isolated for missions such as Earth observing, broadcasting and telecommunication between antenna and ground stations. For space applications, technicians designing controller have to consider a periodic vibration and disturbance to ensure system performance and robustness completing various missions. In general, past research isolating vibration commonly used 6 degree order freedom isolators such as Stewart and Mallock platforms. In this study, the vibration isolation device has 3 degree order freedom, one translational and two rotational motions. The origin of the coordinate is located at the center-of-gravity of the upper plane. In this paper, adaptive notch filter finds the disturbance frequency and the reference signal in filtered-x least mean square is generated by the notch frequency. The design parameters of the notch filter are updated continuously using recursive least square algorithm. Therefore, the adaptive filtered-x least mean square algorithm is applied to the vibration suppressing experiment without reference sensor. This paper shows the experimental results of an active vibration control using an adaptive filtered-x least mean squares algorithm.

• Journal of information and communication convergence engineering
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• 제17권3호
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• pp.205-212
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• 2019

Motion tracking and localization devices are an important building block of motion tracking systems in a virtual reality (VR) environment. This study is about improving the accuracy of motion and location for enhancing user immersion in experience type VR environment to position tracking technique. In this study, we propose and test a design of such a device. The module data test of the attitude and heading reference system shows that the implementation with the MPU-9250 sensor is successful and adequate to be used with short operation time. We consider various sensor hardware dependencies of VR, and compare various correction methods and filtering methods to lower the motion to photon (MTP) time that user movement is fully reflected on the display using sensor devices. The Kalman filter is used to combine the accelerometer with the gyroscope in the sensing unit.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.347-360
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• 2008

In this paper, a Hardware-In-the-Loop simulator to simulate attitude control of space craft using momentum wheels is developed. The simulator consists of a spherical air bearing system allowing rotation and tilt in all three axes, three momentum wheels for actuation, and an AHRS (Attitude Heading Reference System). The simulator processes various types of data in PC104 and wirelessly communicates with a host PC using TCP/IP protocol. A simple low-cost momentum wheel assembly set and its drive electronics are also developed. Several experiments are performed to test the performance of the momentum wheels. For the control performance test of the simulator, a PID controller is implemented. The results of experimental demonstrations confirm the feasibility and validity of the Hardware-In-the-Loop simulator developed in the current study.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.91-91
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• 2000

In this paper, the error compensation method of the attitude reference system with low-cost IMU is proposed. In general, the attitude error calculated by gyro grows with time. Therefore the additional information is required to compensate the drift. The attitude angles can be bound by accelerometer mixing algorithm and the heading angle can be aided by GPS velocity information. The Kalman filter is used for error compensation. The result is verified by comparing with the attitude calculated by medium-grade IMU, LP-81.

• Journal of Biosystems Engineering
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• 제18권3호
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• pp.199-208
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• 1993

This study was attempted to develop the eletronic-hydraulic hitch system for controlling the attitude of tractor implements and to investigate control performance of the system through experiments. Main components of the system developed in this study were reference inputs panel, inclination angle detecter, electronic controller consisted of IBM-AT PC and interfaces, electro-hydraulic directional valves and other hydraulic components and three-point hitch linkage. Experiments were carried out to investigate the response of the system to the step and sine inputs. The effects of hydraulic flow rate and dead band on control performance were analized. Attitude of the implement was controlled within 2.4-5.1 degrees to the setting attitude when the hydraulic flow rate was in the range of $0.25-1.5{\ell}/min$. And implement was controlled without rapid amplitude attenuation and phase angle change in the frequency range of 0.02-0.2Hz when the hydraulic flow rate was in the range of $0.25-1.5{\ell}/min$. Control performance of the system can be expected to be improved if the inclination angle detecter show rapid and stable output as the implement moves.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.265-274
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• 2019

본 논문은 저가형 AHRS(: Attitude Heading Reference System)센서를 이용하여 무인 운송체(Unmanned vehicle)의 자세를 무향 칼만 필터 (Unscented Kalman filter)통해 추정하는 방법을 제안한다. 측정된 가속도와 지구자기장 값을 이용하여 UKF의 보정 단계에서 사용될 자세를 계산한다. 롤 (roll)과 피치 (pitch)는 가속도로부터 구해지며 요 (yaw)는 지구 자기장을 이용하여 연산한다. 이때 사용되는 지구자기장 측정값은 강철 효과(hard-iron effect)와 연철 효과(soft-iron effect)에 의해 쉽게 왜곡되기 때문에 계산된 요의 불확실성이 롤이나 피치의 불확실성에 비하여 크다. 본 논문은 이러한 불확실성을 줄이기 위하여 측정된 지구자기장에 포함된 편차성분을 추정하고 보정하여 더 정밀한 요값을 구한다. 제안된 방법을 수조에서의 무인 운송체 항법 실험을 통하여 검증하였다. 실험결과, 자세 추정 성능이 개선되고 이에 따라 위치 추정 성능도 개선됨을 확인하였다.

• 로봇학회논문지
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• 제9권4호
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• pp.216-224
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• 2014

This paper compares methods for attitude estimation of a UUV(Unmanned Underwater Vehicle). Attitude estimation plays a key role in underwater navigation using DVL(Doppler Velocity Log). The paper proposes attitude estimation methods using EKF(Extended Kalman Filter), UKF(Unscented Kalman Filter), and CF(Complementary Filter). It derives methods using the measurements from MEMS-AHRS(Microelectromechanical Systems-Attitude Heading Reference System) and DVL. The methods are used for navigation in a test pool and their navigation performance is compared. The results suggest that even if there is no measurement relative to some absolute landmarks, DVL-only navigation can be useful for navigation in a limited time and range.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.50-53
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• 1989

This paper presents the configuration and performance test results of a SDARS, which consists of three rate gyros and Zilog 8002 microprocessor. Real time hardware-inthe-loop simulation was performed by 3 axis flight motion simulator applying the assumed typical profiles of angular motion. Test results showed that the performance of SDARS was satisfactory. And, attitude errors was reduced by compensation of gyro errors.