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Article
Publication date: 18 August 2021

Xiaoshuang Ma, Xixiang Liu, Chen-Long Li and Shuangliang Che

This paper aims to present a multi-source information fusion algorithm based on factor graph for autonomous underwater vehicles (AUVs) navigation and positioning to address the…

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Abstract

Purpose

This paper aims to present a multi-source information fusion algorithm based on factor graph for autonomous underwater vehicles (AUVs) navigation and positioning to address the asynchronous and heterogeneous problem of multiple sensors.

Design/methodology/approach

The factor graph is formulated by joint probability distribution function (pdf) random variables. All available measurements are processed into an optimal navigation solution by the message passing algorithm in the factor graph model. To further aid high-rate navigation solutions, the equivalent inertial measurement unit (IMU) factor is introduced to replace several consecutive IMU measurements in the factor graph model.

Findings

The proposed factor graph was demonstrated both in a simulated and vehicle environment using IMU, Doppler Velocity Log, terrain-aided navigation, magnetic compass pilot and depth meter sensors. Simulation results showed that the proposed factor graph processes all available measurements into the considerably improved navigation performance, computational efficiency and complexity compared with the un-simplified factor graph and the federal Kalman filtering methods. Semi-physical experiment results also verified the robustness and effectiveness.

Originality/value

The proposed factor graph scheme supported a plug and play capability to easily fuse asynchronous heterogeneous measurements information in AUV navigation systems.

Details

Assembly Automation, vol. 41 no. 5
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 13 July 2022

Guangrun Sheng, Xixiang Liu, Zixuan Wang, Wenhao Pu, Xiaoqiang Wu and Xiaoshuang Ma

This paper aims to present a novel transfer alignment method based on combined double-time observations with velocity and attitude for ships’ poor maneuverability to address the…

132

Abstract

Purpose

This paper aims to present a novel transfer alignment method based on combined double-time observations with velocity and attitude for ships’ poor maneuverability to address the system errors introduced by flexural deformation and installing which are difficult to calibrate.

Design/methodology/approach

Based on velocity and attitude matching, redesigning and deducing Kalman filter model by combining double-time observation. By introducing the sampling of the previous update cycle of the strapdown inertial navigation system (SINS), current observation subtracts previous observation are used as measurements for transfer alignment filter, system error in measurement introduced by deformation and installing can be effectively removed.

Findings

The results of simulations and turntable tests show that when there is a system error, the proposed method can improve alignment accuracy, shorten the alignment process and not require any active maneuvers or additional sensor equipment.

Originality/value

Calibrating those deformations and installing errors during transfer alignment need special maneuvers along different axes, which is difficult to fulfill for ships’ poor maneuverability. Without additional sensor equipment and active maneuvers, the system errors in attitude measurement can be eliminated by the proposed algorithms, meanwhile improving the accuracy of the shipboard SINS transfer alignment.

Details

Assembly Automation, vol. 42 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 16 July 2020

Xiaoshuang Iris Luo and Cyrus Schleifer

The purpose of this paper is to examine the gendered effects of marriage and parenthood on income inequality among police officers.

236

Abstract

Purpose

The purpose of this paper is to examine the gendered effects of marriage and parenthood on income inequality among police officers.

Design/methodology/approach

This study uses survey data collected by the Current Population Survey (CPS) from 1976 to 2018. Ordinary least squares (OLS) regression is employed to analyze the effect of gender, marriage and parenthood on the yearly income of police officers, controlling for other demographic variables.

Findings

The analyses reveal that there is a large income difference among men and women police officers and the compensation processes appear strongly gendered based on family composition. Police women experience a large motherhood income penalty, while police men with traditional family structures have significant income advantages.

Research limitations/implications

While the CPS dataset allows us to track national level trends of within-occupational income inequality, these data are unable to provide detailed information on the specifics of each police job, such as rank of police officers or work experience. Despite these limitations, this study uncovers important patterns in how family structure shapes police income.

Originality/value

The present study fills the knowledge gap about marriage and motherhood penalty among police. This study represents one of the first attempts to explore the gendered compensation processes that are shaped by marriage and parenthood status among police officers at a national level.

Details

Policing: An International Journal, vol. 43 no. 4
Type: Research Article
ISSN: 1363-951X

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