scholarly journals Real-Time Calibration of Magnetometers Using the RLS/ML Algorithm

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 535
Author(s):  
Guocan Cao ◽  
Xiang Xu ◽  
Dacheng Xu
Keyword(s):  
Parameter Estimation ◽  
Real Time ◽  
Calibration Method ◽  
Least Square ◽  
Estimation Methods ◽  
Recursive Least Square ◽  
Ml Estimation ◽  
Time Calibration ◽  
Complete Measurement ◽  
Calibration Algorithm

This study presents a new real-time calibration algorithm for three-axis magnetometers by combining the recursive least square (RLS) estimation and maximum likelihood (ML) estimation methods. Magnetometers are widely employed to determine the heading information by sensing the magnetic field of earth; however, they are vulnerable to ambient magnetic disturbances. This makes the calibration of a magnetometer inevitable before it is employed. In this paper, first, a complete measurement error model of the magnetometer is studied, and a simplified model is developed. Then, the real-time RLS algorithm is introduced and discussed in detail, and the unbiased optimal ML is utilized to improve the accuracy of the parameter estimation. The proposed algorithm is advantageous in correcting the parameters in real time and simultaneously obtaining unbiased parameter estimation. Finally, the simulation and experimental results demonstrate that both the accuracy and computational speed of the proposed algorithm is better than those of the widely used bath-processing method. Moreover, the proposed calibration method can be adopted for calibrating other three-axis sensors.

A real-time calibration method for the systematic errors of a star sensor and gyroscope units based on the payload multiplexed

Optik ◽  
2021 ◽  
Vol 225 ◽  
pp. 165731
Author(s):  
Zhongguang Yang ◽  
Xiaocheng Zhu ◽  
Zhiming Cai ◽  
Wen Chen ◽  
Jinpei Yu
Keyword(s):  
Real Time ◽  
Calibration Method ◽  
Systematic Errors ◽  
Star Sensor ◽  
Time Calibration

REAL-TIME BLIND SOURCE SEPARATION OF ACOUSTIC SIGNALS WITH A RECURSIVE APPROACH

2004 ◽  
Vol 04 (02) ◽  
pp. 193-206 ◽  
Author(s):  
SHUXUE DING ◽  
JIE HUANG ◽  
DAMING WEI
Keyword(s):  
Real Time ◽  
Blind Source Separation ◽  
Correlation Matrix ◽  
Lower Cost ◽  
Source Separation ◽  
Least Square ◽  
Gradient Algorithm ◽  
Normal Equation ◽  
Recursive Least Square ◽  
Second Order Statistics

We propose an approach for real-time blind source separation (BSS), in which the observations are linear convolutive mixtures of statistically independent acoustic sources. A recursive least square (RLS)-like strategy is devised for real-time BSS processing. A normal equation is further introduced as an expression between the separation matrix and the correlation matrix of observations. We recursively estimate the correlation matrix and explicitly, rather than stochastically, solve the normal equation to obtain the separation matrix. As an example of application, the approach has been applied to a BSS problem where the separation criterion is based on the second-order statistics and the non-stationarity of signals in the frequency domain. In this way, we realise a novel BSS algorithm, called exponentially weighted recursive BSS algorithm. The simulation and experimental results showed an improved separation and a superior convergence rate of the proposed algorithm over that of the gradient algorithm. Moreover, this algorithm can converge to a much lower cost value than that of the gradient algorithm.

A New Linearly Polarized Microwave Radiometer Calibration Source

2012 ◽  
Vol 500 ◽  
pp. 341-347
Author(s):  
Xin Biao Wang ◽  
Chang Zeng ◽  
Jing Li ◽  
Jing Shan Jiang
Keyword(s):  
Real Time ◽  
Microwave Radiometer ◽  
Noise Temperature ◽  
Calibration Method ◽  
Calibration Source ◽  
Radiometer Calibration ◽  
Time Calibration ◽  
Linearly Polarized ◽  
Calibration Device

This paper introduces a calibration device for microwave (millimeter and submillimeter) radiometer. The device can provide the microwave radiometer continuously variable linearly polarized noise temperature. The paper also introduces a real-time calibration method to achieve the microwave radiometer calibration, and the test of microwave radiometer sensitivity and linearity.

scholarly journals A Kinematic Calibration Method of a 3T1R 4-Degree-of-Freedom Symmetrical Parallel Manipulator

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 357
Author(s):  
Fengxuan Zhang ◽  
Silu Chen ◽  
Yongyi He ◽  
Guoyun Ye ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Parallel Manipulator ◽  
Kinematic Model ◽  
Calibration Method ◽  
Error Modeling ◽  
Degree Of Freedom ◽  
Least Square ◽  
Kinematic Calibration ◽  
Recursive Least Square ◽  
Local Product ◽  
Branched Chain

This paper proposes a method for kinematic calibration of a 3T1R, 4-degree-of-freedom symmetrical parallel manipulator driven by two pairs of linear actuators. The kinematic model of the individual branched chain is established by using the local product of exponentials formula. Based on this model, the model of the end effector’s pose error is established from a pair of symmetrical branched chains, and a recursive least square method is applied for the parameter identification. By installing built-in sensors at the passive joints, a calibration method for a serial manipulator is eventually extended to this parallel manipulator. Specifically, the sensor installed at the second revolute joint of each branched chain is saved, replaced by numerical calculation according to kinematic constraints. The simulation results validate the effectiveness of the proposed kinematic error modeling and identification methods. The procedure for pre-processing compensation on this 3T1R parallel manipulator is eventually given to improve its absolute positioning accuracy, using the inverse of the calibrated kinematic model.

Dynamic Real-Time Calibration Method for Fiber Bragg Grating Wavelength Demodulation System Based on Tunable Fabry-Perot Filter

2015 ◽  
Vol 35 (8) ◽  
pp. 0806006 ◽  
Author(s):  
王鹏 Wang Peng ◽  
赵洪 Zhao Hong ◽  
刘杰 Liu Jie ◽  
陈俊岐 Chen Junqi ◽  
韩旭 Han Xu
Keyword(s):  
Fiber Bragg Grating ◽  
Real Time ◽  
Calibration Method ◽  
Bragg Grating ◽  
Time Calibration ◽  
Fabry Perot

scholarly journals Unification of Internal Resistance Estimation Methods for Li-Ion Batteries Using Hysteresis-Free Equivalent Circuit Models

Batteries ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 32
Author(s):  
S M Rakiul Islam ◽  
Sung-Yeul Park ◽  
Balakumar Balasingam
Keyword(s):  
Parameter Estimation ◽  
Equivalent Circuit ◽  
Electrochemical Impedance ◽  
Estimation Method ◽  
Equivalent Circuit Model ◽  
Parameter Extraction ◽  
Internal Resistance ◽  
Least Square ◽  
Estimation Methods ◽  
Li Ion

Internal resistance is one of the important parameters in the Li-Ion battery. This paper identifies it using two different methods: electrochemical impedance spectroscopy (EIS) and parameter estimation based on equivalent circuit model (ECM). Comparing internal resistance, the conventional parameter estimation method yields a different value than EIS. Therefore, a hysteresis-free parameter identification method based on ECM is proposed. The proposed technique separates hysteresis resistance from the effective resistance. It precisely estimated actual internal resistance, which matches the internal resistance obtained from EIS. In addition, state of charge, open circuit voltage, and different internal equivalent circuit components were identified. The least square method was used to identify the parameters based on ECM. A parameter extraction algorithm to interpret impedance spectrum obtained from the EIS. The algorithm is based on the properties of Nyquist plot, phasor algebra, and resonances. Experiments were conducted using a cellphone pouch battery and a cylindrical 18650 battery.

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