• Title, Summary, Keyword: Attitude angular measurement

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Real-Time Compensation of Errors Caused by the Flux Density Non-uniformity for a Magnetically Suspended Sensitive Gyroscope

  • Chaojun, Xin;Yuanwen, Cai;Yuan, Ren;Yahong, Fan;Yongzhi, Su
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.315-325
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    • 2017
  • Magnetically suspended sensitive gyroscopes (MSSGs) provide an interesting alternative for achieving precious attitude angular measurement. To effectively reduce the measurement error caused by the non-uniformity of the air-gap flux density in a MSSG, this paper proposes a novel compensation method based on measuring and modeling of the air-gap flux density. The angular velocity measurement principle and the structure of the MSSG are described, and then the characteristic of the air-gap flux density has been analyzed in detail. Next, to compensate the flux density distribution error and improve the measurement accuracy of the MSSG, a real-time compensation method based on the online measurement with hall probes is designed. The common issues caused by the non-uniformity of the air-gap flux density can be effectively resolved by the proposed method in high-precision magnetically suspended configurations. Comparative simulation results before and after compensation have verified the effectiveness and superiority of the proposed compensation method.

A Triple Nested PID Controller based on Sensor Fusion for Quadrotor Attitude Stabilization (쿼드로터 자세 안정화를 위한 센서융합 기반 3중 중첩 PID 제어기)

  • Cho, Youngwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.7
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    • pp.871-877
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    • 2018
  • In this paper, we propose a triple nested PID control scheme for stable hovering of a quadrotor and propose a complementary filter based sensor fusion technique to improve the performance of attitude, altitude and velocity measurement. The triple nested controller has a structure in which a double nested attitude controller that has the angular velocity PD controller in inner loop and the angular PI controller in outer loop, is nested in a velocity control loop to enable stable hovering even in the case of disturbance. We also propose a sensor fusion technique by applying a complementary filter in order to reduce the noise and drift error included in the acceleration and gyro sensor and to measure the velocity by fusing image, gyro, and acceleration sensor. In order to verity the performance, we applied the proposed control and measurement scheme to hovering control of quadrotor.

Analysis, Modeling and Compensation of Dynamic Imbalance Error for a Magnetically Suspended Sensitive Gyroscope

  • Xin, Chaojun;Cai, Yuanwen;Ren, Yuan;Fan, Yahong;Xu, Guofeng;Lei, Xu
    • Journal of Magnetics
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    • v.21 no.4
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    • pp.529-536
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    • 2016
  • Magnetically suspended sensitive gyroscopes (MSSGs) provide an interesting alternative for achieving precious attitude angular measurement. To effectively reduce the measurement error caused by dynamic imbalance, this paper proposes a novel compensation method based on analysis and modeling of the error for a MSSG. Firstly, the angular velocity measurement principle of the MSSG is described. Then the analytical model of dynamic imbalance error has been established by solving the complex coefficient differential dynamic equations of the rotor. The generation mechanism and changing regularity of the dynamic imbalance error have been revealed. Next, a compensation method is designed to compensate the dynamic imbalance error and improve the measurement accuracy of the MSSG. The common issues caused by dynamic imbalance can be effectively resolved by the proposed method in gyroscopes with a levitating rotor. Comparative simulation results before and after compensation have verified the effectiveness and superiority of the proposed compensation method.

Compensation On-line of Errors Caused by Rotor Centrifugal Deformation for a Magnetically Suspended Sensitive Gyroscope

  • Xin, Chao-Jun;Cai, Yuan-Wen;Ren, Yuan;Fan, Ya-Hong
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.1030-1041
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    • 2018
  • The aim of this paper is to design a centrifugal deformation error compensation method with guaranteed performance that allows angular velocity measurement of the magnetically suspended sensitive gyroscopes (MSSGs). The angular velocity measurement principle and the structure of the MSSG are described, and the analytical model of errors caused by MSSG rotor centrifugal deformation is established. Then, an on-line rotor centrifugal deformation error compensation method based on measurement of rotor spinning speed in real-time has been designed. The common issues caused by centrifugal deformation of spinning rotors can be effectively resolved by the proposed method. Comparative experimental results before and after compensation demonstrate the validity and superiority of the error compensation method.

A Transfer Alignment Method considering a Data Latency Compensation for an Inertial Navigation System in High Dynamic Applications (고기동 환경에서 관성항법장치의 시간지연 보상 전달정렬 기법)

  • Lee, Hyung-Sub;Han, Kyung-Jun;Lee, Sang-Woo;Yu, Myung-Jong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.12
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    • pp.1742-1747
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    • 2015
  • An improved transfer alignment method for a strap-down inertial navigation system (SDINS) is presented here. The alignment accuracy in conventional method is vulnerable to the data latency of a Master INS (MINS) in high maneuverable platforms. We propose a time delay compensation equation considering higher-order terms in the attitude measurement equation of the Kalman filter. The equation incorporates additional information including angular rate, angular acceleration and linear acceleration from the MINS. Simulation results show that the transfer alignment accuracy is significantly improved in the high dynamic environment by incorporating the latency compensation technique.

The Improvement of Tracking Accuracy of the Ground-Based Radar By the Measurement of Dynamic Attitude (지상레이더의 동적 자세 측정을 통한 추적 정확도 개선)

  • Kim, Wan-Kyu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.8
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    • pp.766-773
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    • 2011
  • The inclination attitude of the Ground-Based Radar can be measured by the accelerometer due to its static operation environment, but the measurement error is generated from the angular acceleration of the accelerometer, which is created in mechanical oscillation by the dynamic environment, like the wind, gust, rotating antenna, etc. In this paper, the technique of reducing the measurement error of the attitude by the dynamic attitude is proposed and the result of the simulation and the analysis of tracking error by the attitude error are presented.

Performance Improvement of an INS by using a Magnetometer with Pedestrian Dynamic Constraints

  • Woyano, Feyissa;Park, Aangjoon;Lee, Soyeon
    • IEIE Transactions on Smart Processing and Computing
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    • v.6 no.1
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    • pp.1-9
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    • 2017
  • This paper proposes to improve the performance of a strap down inertial navigation system using a foot-mounted low-cost inertial measurement unit/magnetometer by configuring an attitude and heading reference system. To track position accurately and for attitude estimations, considering different dynamic constraints, magnetic measurement and a zero velocity update technique is used. A conventional strap down method based on integrating angular rate to determine attitude will inevitably induce long-term drift, while magnetometers are subject to short-term orientation errors. To eliminate this accumulative error, and thus, use the navigation system for a long-duration mission, a hybrid configuration by integrating a miniature micro electromechanical system (MEMS)-based attitude and heading detector with the conventional navigation system is proposed in this paper. The attitude and heading detector is composed of three-axis MEMS accelerometers and three-axis MEMS magnetometers. With an absolute algorithm based on gravity and Earth's magnetic field, rather than an integral algorithm, the attitude detector can obtain an absolute attitude and heading estimation without drift errors, so it can be used to adjust the attitude and orientation of the strap down system. Finally, we verify (by both formula analysis and from test results) that the accumulative errors are effectively eliminated via this hybrid scheme.

Force-To-Rebalance Mode of a Resonator Gyro and Angular Rate Measurement Tests (공진 자이로의 재평형 모드 구현과 각속도 측정 실험)

  • Jin, Jaehyun;Kim, Dongguk
    • Journal of Institute of Control, Robotics and Systems
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    • v.20 no.5
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    • pp.563-569
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    • 2014
  • This article focuses on a hemispherical resonator gyro driven by the Coriolis effect. A hemispherical shell, called a resonator, is maintained in the resonance state by amplitude control and phase locking control. Parametric excitation has been used to control the amplitude. For rate measurement mode or FTR mode, nodal points have been kept to an amplitude of zero. Angular rate measurement has been demonstrated by rotating a resonator. Frequency mismatch between two stiffness principal axes is a major cause of low performance: vibrating pattern drift and reduced control effectiveness. This mismatch has been reduced significantly by the addition of small mass. A negative spring effect, which lowers resonance frequencies, has been verified experimentally.

A miniaturized attitude estimation system for a gesture-based input device with fuzzy logic approach

  • Wook Chang;Jing Yang;Park, Eun-Seok;Bang, Won-Chul;Kang, Kyoung-Ho;Cho, Sung-Jung;Kim, Dong-Yoon
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.616-619
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    • 2003
  • In this paper, we develop an input device equipped with accelerometers and gyroscopes. The installed sensors measure the inertial measurements i.e., accelerations and angular rates produced by the movement of the system when a user is writing on the plane surface or in the three dimensional space. The gyroscope measurement are integrated once to give the attitude of the system and consequently used to remove the gravity included in the acceleration measurements. The compensated accelerations bin doubly integrated to yield the position of the system. Due to the integration processes involved in recovering the users'motions, the accuracy of the position estimation significantly deteriorates with time. Among various error sources of the system incorrect estimation of attitude causes the largest portion of the positioning error since the gravity is not fully cancelled. In order to solve this problem, we propose a Kalman filler-based attitude estimation algorithm which fuses measurement data from accelerometers and gyroscopes by fuzzy logic approach. In addition, the online calibration of the gyroscope biases are performed in parallel with the attitude estimation to give more accurate attitude estimation. The effectiveness and the feasibility of the presented system is demonstrated through computer simulations and actual experiments.

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Design and Analysis of Lorentz Force-type Magnetic Bearing Based on High Precision and Low Power Consumption

  • Xu, Guofeng;Cai, Yuanwen;Ren, Yuan;Xin, Chaojun;Fan, Yahong;Hu, Dengliang
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.203-213
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    • 2017
  • Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.