scholarly journals Error Analysis of Accelerometer- and Magnetometer-Based Stationary Alignment

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2040
Author(s):  
Felipe O. Silva ◽  
Lucas P. S. Paiva ◽  
Gustavo S. Carvalho
Keyword(s):  
Error Analysis ◽  
Attitude Determination ◽  
Direction Cosine ◽  
Systematic Errors ◽  
Earth Magnetic Field ◽  
Local Gravity ◽  
Declination Angle ◽  
Determination Methods ◽  
Alignment Errors ◽  
Residual Errors

This paper revisits the stationary attitude initialization problem, i.e., the stationary alignment, of Attitude and Heading Reference Systems (AHRSs). A detailed and comprehensive error analysis is proposed for four of the most representative accelerometer- and magnetometer-based stationary attitude determination methods, namely, the Three-Axis Attitude Determination (TRIAD), the QUaternion ESTimator (QUEST), the Factored Quaternion Algorithm (FQA), and the Arc-TANgent (ATAN). For the purpose of the error analysis, constant biases in the accelerometer and magnetometer measurements are considered (encompassing, hence, the effect of hard-iron magnetism), in addition to systematic errors in the local gravity and Earth magnetic field models (flux density magnitude, declination angle, and inclination angle). The contributions of this paper are novel closed-form formulae for the residual errors (normality, orthogonality, and alignment errors) developed in the computed Direction Cosine Matrices (DCM). As a consequence, analytical insight is provided into the problem, allowing us to properly compare the performance of the investigated alignment formulations (in terms of ultimate accuracy), as well as to remove some misleading conclusions reported in previous works. The adequacy of the proposed error analysis is validated through simulation and experimental results.

The Error Analysis about Gauge Visual Detection System between High Signals and Contact Net

2012 ◽  
Vol 522 ◽  
pp. 347-350
Author(s):  
Xi Lin Zhu ◽  
Yong Yu ◽  
Qiang Wei ◽  
Xiang Zou ◽  
Chen Jun Huang
Keyword(s):  
Image Processing ◽  
Error Analysis ◽  
System Design ◽  
Visual Detection ◽  
Imaging System ◽  
Detection System ◽  
Systematic Errors ◽  
Lighting Conditions ◽  
Specific Impact

t is need to experiment to verify the correctness and validity of various stages in system design after gauge visual detection system designing between high signals and contact net. Then it does error analysis from lighting conditions, camera resolution, binocular imaging system installation structure, camera out of synchronized, noise and subsequent image processing operations, etc. It analysis the systematic errors principle and specific impact, then identifies specific improvements.

scholarly journals Kesalahan Penggunaan Kata Bantu Bilangan Bahasa Mandarin pada Siswa Indonesia Tingkat Prapemula

2015 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Ayu Trihardini
Keyword(s):  
Error Analysis ◽  
Research Design ◽  
Mother Tongue ◽  
Systematic Errors ◽  
Teaching Techniques ◽  
Research Results

The purpose of this study was to analyze Indonesian breakthrough level students’ errors in using Mandarin measure words. The collected data were the errors made by students of Prodi Pendidikan Bahasa Mandarin UNJ who attend Conversation II course (CEFR A1/breakthrough) on written and oral utterance. This study used Zhou Xiaobin’s research design in Mandarin measure words error analysis, with the Carl James model of identification errors. The result of this study shows Indonesian students’ errors in using Mandarin measure words can be determined as follows: omission, misselection, misordering, and blends. Furthermore, this study proves that there are systematic errors made by students with different mother tongue and at the same level of learning Mandarin. The research results can be used to develop Mandarin measure words teaching techniques based on error analysis.

scholarly journals A Prospective Study to Investigate the Placement of Setup Skin Markings for Larger Breasted Women Undergoing External Beam Radiotherapy (RT) for Breast Cancer

2019 ◽  
pp. 99-122
Author(s):  
Chris Osam Doudoo ◽  
Neill Roberts ◽  
Emmanuel Amankwaa Frempong ◽  
Clement Edusa ◽  
Kwamena Beecham ◽  
...  
Keyword(s):  
Breast Cancer ◽  
External Beam Radiotherapy ◽  
Systematic Errors ◽  
Patient Treatment ◽  
P Value ◽  
Alignment Error ◽  
External Beam ◽  
Significant Difference ◽  
Portal Images ◽  
Alignment Errors

Background: The technique of placing all three skin marks (reference skin marks) on a single position during CT simulation for setup of patients undergoing conventional breast radiotherapy becomes a challenge when presented with larger breasted women (bra cup size ≥ D). A new way of using skin marks in setting these patients up has been developed where three skin marks are made on the patient (one on the sternum and two lateral skin marks more inferiorly beneath the breasts) for setup as against the departmental standard of using only a single skin mark on the sternum, and employing an SSD (Source to Skin Distance) technique. This study therefore reviewed the placement of the skin markings for larger breasted women undergoing external beam radiotherapy for breast cancer by quantifying treatment field alignment errors and setup errors between the two different setup techniques. Method: 36 patients were used in this study. Out of this number, 18 were setup using three reference skin marks and the remaining 18 were setup using one reference anterior skin mark. With an acceptable patient treatment field alignment error of 2 degrees, portal images (AP and lateral) of the different skin mark techniques were analysed for field alignment errors using an Iview GT system. More so, portal images (AP and lateral) of setup for both techniques were analysed for systematic (Σ) and random (σ) errors. Results:The AP images of the single skin mark setup and the three skin mark setup yielded no significant difference as they recorded a p- value (p<0.05) of 0.089 and 0.110 respectively when compared to the treatment field alignment threshold error of 2 degrees. The lateral images of the three skin mark also yielded no significant difference as a p- value (p<0.05) of 0.091 was recorded. The lateral images of the single skin mark yielded a significant difference with a p- value (p<0.05) of 0.026. Secondly, mean comparisons of the field alignment errors between the two setup techniques yielded no significant difference in the AP images as a p- value (p<0.05) of 0.089 was detected. On the contrary, a p- value (p<0.05) of 0.026 was recorded in the field alignment errors of the lateral images. This difference is significant. Lastly, random errors were reduced in all directions (AP- anterior-posterior, SI- superior-inferior and LR- Left-right) in the three skin mark setup (4.5mm AP, 4.9mm SI and 2.4mm LR) as compared to the single skin mark setup (4.7mm AP, 5.2mm SI and 2.6mm LR). Systematic errors were also reduced in the three skin mark setup (1.7mm AP and 1.8mm SI) compared to the single skin mark setup (2.0mm AP, 2.1mm SI). Systematic errors in the LR direction on the other hand increased from 2.0mm in the single skin mark to 2.2mm in the three skin marks. Conclusion For setup of larger breasted women undergoing external beam radiotherapy for breast cancer, the three skin mark setup technique is superior to the single skin mark setup technique.

scholarly journals Optimal attitude determination method in presence of noise and bias on different star sensors

2014 ◽  
Vol 3 (2) ◽  
pp. 155 ◽  
Author(s):  
Amir Moghtadaei Rad
Keyword(s):  
Attitude Determination ◽  
Least Square Method ◽  
Least Square ◽  
Optimal Method ◽  
Input Noise ◽  
Advantages And Disadvantages ◽  
Celestial Navigation ◽  
Stochastic Characteristic ◽  
Determination Methods ◽  
N Vector

There are different attitude determination methods which have been used in satellite and spacecraft by star tracker. Each of these methods have its own advantages and disadvantages depending on their application, stochastic characteristic of noise on sensors (bias or noise), and weight of noise falling on different sensors. The present study has thus explored the major methods from two perspectives: the effect of input noise or bias on each star sensor and the corresponding weight of each noise or bias falling on each sensor. These aspects are compared in each method and the optimal method according to each condition is introduced. N Vector, Triad, Quest, Q method and least square method are the methods studied and simulated in this article. Finally, a comparison is made between the methods and the optimal method is introduced theoretically and practically. Keywords: Attitude Determination, Celestial Navigation, Triad, Quest, Least Square, Satellite.

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