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Inertial Sensors for Positioning and Navigation

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (10 October 2017) | Viewed by 158981

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Special Issue Editors

Prof. Dr. Allison Kealy

E-Mail Website
Guest Editor

School of Science, RMIT University, Melbourne, VIC 3001, Australia
Interests: positioning (sensor fusion, ubiquitous positioning; localization in wireless sensor networks); satellite positioning systems; (quality control for CORS GNSS networks and GNSS for weather forecasting)
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Günther Retscher

E-Mail Website
Guest Editor

Engineering Geodesy, Institute of Geodesy and Geophysics, Vienna University of Technology, 1040 Vienna, Austria
Interests: Positioning and Navigation with GNSS; Location Based Services (LBS); Indoor and Pedestrian Navigation; Applications of Multi-sensor Systems
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Gert F. Trommer

E-Mail Website
Guest Editor

Institute of Systems Optimization (ITE), Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 1, 76131 Karlsruhe, Germany
Interests: inertial sensors and systems; unmanned aerial systems (UAS); indoor navigation; guidance, navigation and control of mobile platforms
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Inertial Navigation Systems (INS) have become a key component of navigation and positioning systems for indoor and GNSS denied environments. Their uses range from high precision systems for aerospace or maritime applications, medium performance systems for land vehicles and indoor navigation, as well as the low performance consumer market for smart phones and games. The increasing spectrum of applications demanding a better balance between performance and cost, such as driverless vehicles, have encouraged innovations across INS hardware, error modeling, and fusion techniques.

This Special Issue aims to highlight these innovations and showcase the performance capabilities and emerging applications for INS. Topics include, but are not limited, to:

Accelerometers
High Performance Gyroscopes
MEMS Sensors
Advanced Sensor Characterization Techniques
Sensor Error Modeling and Online Calibration
Advanced Test and Evaluation
Sensor Fusion
Algorithms and Methods
Wearable sensors
Innovative applications

Prof. Dr. Allison Kealy
Prof. Dr. Günther Retscher
Prof. Dr. Gert F. Trommer
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

inertial sensors
navigation
positioning
gyroscopes
accelerometers
mems sensors
sensor fusion

Published Papers (29 papers)

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Research

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12 pages, 2428 KiB

Open AccessArticle

Error Analysis of the K-Rb-²¹Ne Comagnetometer Space-Stable Inertial Navigation System

by Qingzhong Cai, Gongliu Yang, Wei Quan, Ningfang Song, Yongqiang Tu and Yiliang Liu

Sensors 2018, 18(2), 670; https://doi.org/10.3390/s18020670 - 24 Feb 2018

Cited by 10 | Viewed by 5221

According to the application characteristics of the K-Rb-²¹Ne comagnetometer, a space-stable navigation mechanization is designed and the requirements of the comagnetometer prototype are presented. By analysing the error propagation rule of the space-stable Inertial Navigation System (INS), the three biases, the [...] Read more.

According to the application characteristics of the K-Rb-²¹Ne comagnetometer, a space-stable navigation mechanization is designed and the requirements of the comagnetometer prototype are presented. By analysing the error propagation rule of the space-stable Inertial Navigation System (INS), the three biases, the scale factor of the z-axis, and the misalignment of the x- and y-axis non-orthogonal with the z-axis, are confirmed to be the main error source. A numerical simulation of the mathematical model for each single error verified the theoretical analysis result of the system’s error propagation rule. Thus, numerical simulation based on the semi-physical data result proves the feasibility of the navigation scheme proposed in this paper. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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27 pages, 5485 KiB

Open AccessArticle

A Novel Grid SINS/DVL Integrated Navigation Algorithm for Marine Application

by Yingyao Kang, Lin Zhao, Jianhua Cheng, Mouyan Wu and Xiaoliang Fan

Sensors 2018, 18(2), 364; https://doi.org/10.3390/s18020364 - 26 Jan 2018

Cited by 36 | Viewed by 4825

Integrated navigation algorithms under the grid frame have been proposed based on the Kalman filter (KF) to solve the problem of navigation in some special regions. However, in the existing study of grid strapdown inertial navigation system (SINS)/Doppler velocity log (DVL) integrated navigation [...] Read more.

Integrated navigation algorithms under the grid frame have been proposed based on the Kalman filter (KF) to solve the problem of navigation in some special regions. However, in the existing study of grid strapdown inertial navigation system (SINS)/Doppler velocity log (DVL) integrated navigation algorithms, the Earth models of the filter dynamic model and the SINS mechanization are not unified. Besides, traditional integrated systems with the KF based correction scheme are susceptible to measurement errors, which would decrease the accuracy and robustness of the system. In this paper, an adaptive robust Kalman filter (ARKF) based hybrid-correction grid SINS/DVL integrated navigation algorithm is designed with the unified reference ellipsoid Earth model to improve the navigation accuracy in middle-high latitude regions for marine application. Firstly, to unify the Earth models, the mechanization of grid SINS is introduced and the error equations are derived based on the same reference ellipsoid Earth model. Then, a more accurate grid SINS/DVL filter model is designed according to the new error equations. Finally, a hybrid-correction scheme based on the ARKF is proposed to resist the effect of measurement errors. Simulation and experiment results show that, compared with the traditional algorithms, the proposed navigation algorithm can effectively improve the navigation performance in middle-high latitude regions by the unified Earth models and the ARKF based hybrid-correction scheme. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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16 pages, 1457 KiB

Open AccessArticle

Sculling Compensation Algorithm for SINS Based on Two-Time Scale Perturbation Model of Inertial Measurements

by Lingling Wang, Li Fu and Ming Xin

Sensors 2018, 18(1), 282; https://doi.org/10.3390/s18010282 - 18 Jan 2018

Cited by 7 | Viewed by 4236

In order to decrease the velocity sculling error under vibration environments, a new sculling error compensation algorithm for strapdown inertial navigation system (SINS) using angular rate and specific force measurements as inputs is proposed in this paper. First, the sculling error formula in [...] Read more.

In order to decrease the velocity sculling error under vibration environments, a new sculling error compensation algorithm for strapdown inertial navigation system (SINS) using angular rate and specific force measurements as inputs is proposed in this paper. First, the sculling error formula in incremental velocity update is analytically derived in terms of the angular rate and specific force. Next, two-time scale perturbation models of the angular rate and specific force are constructed. The new sculling correction term is derived and a gravitational search optimization method is used to determine the parameters in the two-time scale perturbation models. Finally, the performance of the proposed algorithm is evaluated in a stochastic real sculling environment, which is different from the conventional algorithms simulated in a pure sculling circumstance. A series of test results demonstrate that the new sculling compensation algorithm can achieve balanced real/pseudo sculling correction performance during velocity update with the advantage of less computation load compared with conventional algorithms. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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10 pages, 3720 KiB

Open AccessArticle

Angular Molecular–Electronic Sensor with Negative Magnetohydrodynamic Feedback

by Egor Egorov, Vadim Agafonov, Svetlana Avdyukhina and Sergey Borisov

Sensors 2018, 18(1), 245; https://doi.org/10.3390/s18010245 - 16 Jan 2018

Cited by 23 | Viewed by 4190

A high-precision angular accelerometer based on molecular–electronic transfer (MET) technology with a high dynamic range and a low level of self-noise has been developed. Its difference from the analogues is in the use of liquid (electrolyte) as the inertial mass and the use [...] Read more.

A high-precision angular accelerometer based on molecular–electronic transfer (MET) technology with a high dynamic range and a low level of self-noise has been developed. Its difference from the analogues is in the use of liquid (electrolyte) as the inertial mass and the use of negative feedback based on the magnetohydrodynamic effect. This article reports on the development of the angular molecular–electronic accelerometer with a magnetohydrodynamic cell for the creation of negative feedback, and the optimization of electronics for the creation of a feedback signal. The main characteristics of the angular accelerometer, such as amplitude–frequency characteristics, self-noise and Allan variance were experimentally measured. The obtained output parameters were compared to its analogues and it showed perspectives for further development in this field. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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11 pages, 1507 KiB

Open AccessArticle

An Improved Coarse Alignment Algorithm for Odometer-Aided SINS Based on the Optimization Design Method

by Yonggang Zhang, Li Luo, Tao Fang, Ning Li and Guoqing Wang

Sensors 2018, 18(1), 195; https://doi.org/10.3390/s18010195 - 11 Jan 2018

Cited by 20 | Viewed by 3341

An improved coarse alignment (ICA) algorithm is proposed in this paper with a focus on improving alignment accuracy of odometer-aided strapdown inertial navigation system (SINS) under variable velocity and variable acceleration condition. In the proposed algorithm, the outputs of inertial sensors and odometer [...] Read more.

An improved coarse alignment (ICA) algorithm is proposed in this paper with a focus on improving alignment accuracy of odometer-aided strapdown inertial navigation system (SINS) under variable velocity and variable acceleration condition. In the proposed algorithm, the outputs of inertial sensors and odometer in a sampling interval are linearized rather than assumed to be a constant, which improves the accuracy of the vector observations and the precision of coarse alignment. Simulation and field test results illustrate that, under variable velocity and variable acceleration condition, the proposed algorithm can obtain a better alignment performance than conventional coarse alignment method. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2112 KiB

Open AccessArticle

Location Accuracy of INS/Gravity-Integrated Navigation System on the Basis of Ocean Experiment and Simulation

by Hubiao Wang, Lin Wu, Hua Chai, Lifeng Bao and Yong Wang

Sensors 2017, 17(12), 2961; https://doi.org/10.3390/s17122961 - 20 Dec 2017

Cited by 18 | Viewed by 4503

An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly [...] Read more.

An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly reference map and multi-model adaptive Kalman filtering algorithm, a matching location experiment of IGNS was conducted using data obtained using marine gravimeter. The location accuracy under actual ocean conditions was 2.83 nautical miles (n miles). Several groups of simulated data of marine gravity anomalies were obtained by establishing normally distributed random error

N (u, σ^{2})

with varying mean

u

and noise variance

σ^{2}

. Thereafter, the matching location of IGNS was simulated. The results show that the changes in

u

had little effect on the location accuracy. However, an increase in

σ^{2}

resulted in a significant decrease in the location accuracy. A comparison between the actual ocean experiment and the simulation along the same route demonstrated the effectiveness of the proposed simulation method and quantitative analysis results. In addition, given the gravimeter (1–2 mGal accuracy) and the reference map (resolution 1′ × 1′; accuracy 3–8 mGal), location accuracy of IGNS was up to reach ~1.0–3.0 n miles in the South China Sea. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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5606 KiB

Open AccessArticle

A Novel Adaptive H∞ Filtering Method with Delay Compensation for the Transfer Alignment of Strapdown Inertial Navigation Systems

by Weiwei Lyu and Xianghong Cheng

Sensors 2017, 17(12), 2753; https://doi.org/10.3390/s17122753 - 28 Nov 2017

Cited by 10 | Viewed by 3522

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in [...] Read more.

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2476 KiB

Open AccessArticle

Stochastic Integration H_∞ Filter for Rapid Transfer Alignment of INS

by Dapeng Zhou and Lei Guo

Sensors 2017, 17(11), 2670; https://doi.org/10.3390/s17112670 - 18 Nov 2017

Cited by 2 | Viewed by 3362

The performance of an inertial navigation system (INS) operated on a moving base greatly depends on the accuracy of rapid transfer alignment (RTA). However, in practice, the coexistence of large initial attitude errors and uncertain observation noise statistics poses a great challenge for [...] Read more.

The performance of an inertial navigation system (INS) operated on a moving base greatly depends on the accuracy of rapid transfer alignment (RTA). However, in practice, the coexistence of large initial attitude errors and uncertain observation noise statistics poses a great challenge for the estimation accuracy of misalignment angles. This study aims to develop a novel robust nonlinear filter, namely the stochastic integration H

_{\infty}

filter (SIH

_{\infty}

F) for improving both the accuracy and robustness of RTA. In this new nonlinear H

_{\infty}

filter, the stochastic spherical-radial integration rule is incorporated with the framework of the derivative-free H

_{\infty}

filter for the first time, and the resulting SIH

_{\infty}

F simultaneously attenuates the negative effect in estimations caused by significant nonlinearity and large uncertainty. Comparisons between the SIH

_{\infty}

F and previously well-known methodologies are carried out by means of numerical simulation and a van test. The results demonstrate that the newly-proposed method outperforms the cubature H

_{\infty}

filter. Moreover, the SIH

_{\infty}

F inherits the benefit of the traditional stochastic integration filter, but with more robustness in the presence of uncertainty. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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4430 KiB

Open AccessArticle

System Modeling of a MEMS Vibratory Gyroscope and Integration to Circuit Simulation

by Hyukjin J. Kwon, Seyeong Seok and Geunbae Lim

Sensors 2017, 17(11), 2663; https://doi.org/10.3390/s17112663 - 18 Nov 2017

Cited by 18 | Viewed by 7380

Recently, consumer applications have dramatically created the demand for low-cost and compact gyroscopes. Therefore, on the basis of microelectromechanical systems (MEMS) technology, many gyroscopes have been developed and successfully commercialized. A MEMS gyroscope consists of a MEMS device and an electrical circuit for [...] Read more.

Recently, consumer applications have dramatically created the demand for low-cost and compact gyroscopes. Therefore, on the basis of microelectromechanical systems (MEMS) technology, many gyroscopes have been developed and successfully commercialized. A MEMS gyroscope consists of a MEMS device and an electrical circuit for self-oscillation and angular-rate detection. Since the MEMS device and circuit are interactively related, the entire system should be analyzed together to design or test the gyroscope. In this study, a MEMS vibratory gyroscope is analyzed based on the system dynamic modeling; thus, it can be mathematically expressed and integrated into a circuit simulator. A behavioral simulation of the entire system was conducted to prove the self-oscillation and angular-rate detection and to determine the circuit parameters to be optimized. From the simulation, the operating characteristic according to the vacuum pressure and scale factor was obtained, which indicated similar trends compared with those of the experimental results. The simulation method presented in this paper can be generalized to a wide range of MEMS devices. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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3793 KiB

Open AccessArticle

Combining a Disturbance Observer with Triple-Loop Control Based on MEMS Accelerometers for Line-of-Sight Stabilization

by Yong Luo, Yongmei Huang, Chao Deng, Yao Mao, Wei Ren and Qiongyan Wu

Sensors 2017, 17(11), 2648; https://doi.org/10.3390/s17112648 - 17 Nov 2017

Cited by 11 | Viewed by 5206

In the CCD-based fine tracking optical system (FTOS), the whole disturbance suppression ability (DSA) is the product of the inner loop and outer position loop. Traditionally, high sampling fiber-optic gyroscopes (FOGs) are added to the platform to stabilize the line-of-sight (LOS). However, because [...] Read more.

In the CCD-based fine tracking optical system (FTOS), the whole disturbance suppression ability (DSA) is the product of the inner loop and outer position loop. Traditionally, high sampling fiber-optic gyroscopes (FOGs) are added to the platform to stabilize the line-of-sight (LOS). However, because of the FOGs’ high cost and relatively big volume relative to the back narrow space of small rotating mirrors, we attempt in this work to utilize a cheaper and smaller micro-electro-mechanical system (MEMS) accelerometer to build the inner loop, replacing the FOG. Unfortunately, since accelerometers are susceptible to the low-frequency noise, according to the classical way of using accelerometers, the crucial low-frequency DSA of the system is insufficient. To solve this problem, in this paper, we propose an approach based on MEMS accelerometers combining disturbance observer (DOB) with triple-loop control (TLC) in which the composite velocity loop is built by acceleration integration and corrected by CCD. The DOB is firstly used to reform the platform, greatly improving the medium-frequency DSA. Then the composite velocity loop exchanges a part of medium-frequency performance for the low-frequency DSA. A detailed analysis and experiments verify the proposed method has a better DSA than the traditional way and could totally substitute FOG in the LOS stabilization. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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11452 KiB

Open AccessArticle

A Smartphone Step Counter Using IMU and Magnetometer for Navigation and Health Monitoring Applications

by Maan Khedr and Nasser El-Sheimy

Sensors 2017, 17(11), 2573; https://doi.org/10.3390/s17112573 - 08 Nov 2017

Cited by 29 | Viewed by 9803

The growing market of smart devices make them appealing for various applications. Motion tracking can be achieved using such devices, and is important for various applications such as navigation, search and rescue, health monitoring, and quality of life-style assessment. Step detection is a [...] Read more.

The growing market of smart devices make them appealing for various applications. Motion tracking can be achieved using such devices, and is important for various applications such as navigation, search and rescue, health monitoring, and quality of life-style assessment. Step detection is a crucial task that affects the accuracy and quality of such applications. In this paper, a new step detection technique is proposed, which can be used for step counting and activity monitoring for health applications as well as part of a Pedestrian Dead Reckoning (PDR) system. Inertial and Magnetic sensors measurements are analyzed and fused for detecting steps under varying step modes and device pose combinations using a free-moving handheld device (smartphone). Unlike most of the state of the art research in the field, the proposed technique does not require a classifier, and adaptively tunes the filters and thresholds used without the need for presets while accomplishing the task in a real-time operation manner. Testing shows that the proposed technique successfully detects steps under varying motion speeds and device use cases with an average performance of 99.6%, and outperforms some of the state of the art techniques that rely on classifiers and commercial wristband products. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2424 KiB

Open AccessArticle

Loose Coupling of Wearable-Based INSs with Automatic Heading Evaluation

by Dina Bousdar Ahmed and Estefania Munoz Diaz

Sensors 2017, 17(11), 2534; https://doi.org/10.3390/s17112534 - 03 Nov 2017

Cited by 9 | Viewed by 4109

Position tracking of pedestrians by means of inertial sensors is a highly explored field of research. In fact, there are already many approaches to implement inertial navigation systems (INSs). However, most of them use a single inertial measurement unit (IMU) attached to the [...] Read more.

Position tracking of pedestrians by means of inertial sensors is a highly explored field of research. In fact, there are already many approaches to implement inertial navigation systems (INSs). However, most of them use a single inertial measurement unit (IMU) attached to the pedestrian’s body. Since wearable-devices will be given items in the future, this work explores the implementation of an INS using two wearable-based IMUs. A loosely coupled approach is proposed to combine the outputs of wearable-based INSs. The latter are based on a pocket-mounted IMU and a foot-mounted IMU. The loosely coupled fusion combines the output of the two INSs not only when these outputs are least erroneous, but also automatically favoring the best output. This approach is named smart update. The main challenge is determining the quality of the heading estimation of each INS, which changes every time. In order to address this, a novel concept to determine the quality of the heading estimation is presented. This concept is subject to a patent application. The results show that the position error rate of the loosely coupled fusion is 10 cm/s better than either the foot INS’s or pocket INS’s error rate in 95% of the cases. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2153 KiB

Open AccessArticle

A New Scale Factor Adjustment Method for Magnetic Force Feedback Accelerometer

by Xiangqing Huang, Zhongguang Deng, Yafei Xie, Zhu Li, Ji Fan and Liangcheng Tu

Sensors 2017, 17(11), 2471; https://doi.org/10.3390/s17112471 - 27 Oct 2017

Cited by 14 | Viewed by 5226

A new and simple method to adjust the scale factor of a magnetic force feedback accelerometer is presented, which could be used in developing a rotating accelerometer gravity gradient instrument (GGI). Adjusting and matching the acceleration-to-current transfer function of the four accelerometers automatically [...] Read more.

A new and simple method to adjust the scale factor of a magnetic force feedback accelerometer is presented, which could be used in developing a rotating accelerometer gravity gradient instrument (GGI). Adjusting and matching the acceleration-to-current transfer function of the four accelerometers automatically is one of the basic and necessary technologies for rejecting the common mode accelerations in the development of GGI. In order to adjust the scale factor of the magnetic force rebalance accelerometer, an external current is injected and combined with the normal feedback current; they are then applied together to the torque coil of the magnetic actuator. The injected current could be varied proportionally according to the external adjustment needs, and the change in the acceleration-to-current transfer function then realized dynamically. The new adjustment method has the advantages of no extra assembly and ease of operation. Changes in the scale factors range from 33% smaller to 100% larger are verified experimentally by adjusting the different external coefficients. The static noise of the used accelerometer is compared under conditions with and without the injecting current, and the experimental results find no change at the current noise level, which further confirms the validity of the presented method. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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4589 KiB

Open AccessArticle

Vibration Noise Modeling for Measurement While Drilling System Based on FOGs

by Chunxi Zhang, Lu Wang, Shuang Gao, Tie Lin and Xianmu Li

Sensors 2017, 17(10), 2367; https://doi.org/10.3390/s17102367 - 17 Oct 2017

Cited by 7 | Viewed by 4636

Aiming to improve survey accuracy of Measurement While Drilling (MWD) based on Fiber Optic Gyroscopes (FOGs) in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF) method. The KF method needs to model the [...] Read more.

Aiming to improve survey accuracy of Measurement While Drilling (MWD) based on Fiber Optic Gyroscopes (FOGs) in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF) method. The KF method needs to model the inertial sensors’ noise as the system noise model. The system noise is modeled as white Gaussian noise conventionally. However, because of the vibration while drilling, the noise in gyros isn’t white Gaussian noise any more. Moreover, an incorrect noise model will degrade the accuracy of KF. This paper developed a new approach for noise modeling on the basis of dynamic Allan variance (DAVAR). In contrast to conventional white noise models, the new noise model contains both the white noise and the color noise. With this new noise model, the KF for the MWD was designed. Finally, two vibration experiments have been performed. Experimental results showed that the proposed vibration noise modeling approach significantly improved the estimated accuracies of the inertial sensor drifts. Compared the navigation results based on different noise model, with the DAVAR noise model, the position error and the toolface angle error are reduced more than 90%. The velocity error is reduced more than 65%. The azimuth error is reduced more than 50%. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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5427 KiB

Open AccessArticle

High-Accuracy Decoupling Estimation of the Systematic Coordinate Errors of an INS and Intensified High Dynamic Star Tracker Based on the Constrained Least Squares Method

by Jie Jiang, Wenbo Yu and Guangjun Zhang

Sensors 2017, 17(10), 2285; https://doi.org/10.3390/s17102285 - 07 Oct 2017

Cited by 7 | Viewed by 4453

Navigation accuracy is one of the key performance indicators of an inertial navigation system (INS). Requirements for an accuracy assessment of an INS in a real work environment are exceedingly urgent because of enormous differences between real work and laboratory test environments. An [...] Read more.

Navigation accuracy is one of the key performance indicators of an inertial navigation system (INS). Requirements for an accuracy assessment of an INS in a real work environment are exceedingly urgent because of enormous differences between real work and laboratory test environments. An attitude accuracy assessment of an INS based on the intensified high dynamic star tracker (IHDST) is particularly suitable for a real complex dynamic environment. However, the coupled systematic coordinate errors of an INS and the IHDST severely decrease the attitude assessment accuracy of an INS. Given that, a high-accuracy decoupling estimation method of the above systematic coordinate errors based on the constrained least squares (CLS) method is proposed in this paper. The reference frame of the IHDST is firstly converted to be consistent with that of the INS because their reference frames are completely different. Thereafter, the decoupling estimation model of the systematic coordinate errors is established and the CLS-based optimization method is utilized to estimate errors accurately. After compensating for error, the attitude accuracy of an INS can be assessed based on IHDST accurately. Both simulated experiments and real flight experiments of aircraft are conducted, and the experimental results demonstrate that the proposed method is effective and shows excellent performance for the attitude accuracy assessment of an INS in a real work environment. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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4984 KiB

Open AccessArticle

High-Sensitivity Encoder-Like Micro Area-Changed Capacitive Transducer for a Nano-g Micro Accelerometer

by Wenjie Wu, Panpan Zheng, Jinquan Liu, Zhu Li, Ji Fan, Huafeng Liu and Liangcheng Tu

Sensors 2017, 17(9), 2158; https://doi.org/10.3390/s17092158 - 20 Sep 2017

Cited by 21 | Viewed by 7870

Encoder-like micro area-changed capacitive transducers are advantageous in terms of their better linearity and larger dynamic range compared to gap-changed capacitive transducers. Such transducers have been widely applied in rectilinear and rotational position sensors, lab-on-a-chip applications and bio-sensors. However, a complete model accounting [...] Read more.

Encoder-like micro area-changed capacitive transducers are advantageous in terms of their better linearity and larger dynamic range compared to gap-changed capacitive transducers. Such transducers have been widely applied in rectilinear and rotational position sensors, lab-on-a-chip applications and bio-sensors. However, a complete model accounting for both the parasitic capacitance and fringe effect in area-changed capacitive transducers has not yet been developed. This paper presents a complete model for this type of transducer applied to a high-resolution micro accelerometer that was verified by both simulations and experiments. A novel optimization method involving the insertion of photosensitive polyimide was used to reduce the parasitic capacitance, and the capacitor spacing was decreased to overcome the fringe effect. The sensitivity of the optimized transducer was approximately 46 pF/mm, which was nearly 40 times higher than that of our previous transducer. The displacement detection resolution was measured as 50 pm/√Hz at 0.1 Hz using a precise capacitance detection circuit. Then, the transducer was applied to a sandwich in-plane micro accelerometer, and the measured level of the accelerometer was approximately 30 ng/√Hz at 1Hz. The earthquake that occurred in Taiwan was also detected during a continuous gravity measurement. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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12690 KiB

Open AccessArticle

A UWB/Improved PDR Integration Algorithm Applied to Dynamic Indoor Positioning for Pedestrians

by Pengzhan Chen, Ye Kuang and Xiaoyue Chen

Sensors 2017, 17(9), 2065; https://doi.org/10.3390/s17092065 - 08 Sep 2017

Cited by 76 | Viewed by 5573

Inertial sensors are widely used in various applications, such as human motion monitoring and pedestrian positioning. However, inertial sensors cannot accurately define the process of human movement, a limitation that causes data drift in the process of human body positioning, thus seriously affecting [...] Read more.

Inertial sensors are widely used in various applications, such as human motion monitoring and pedestrian positioning. However, inertial sensors cannot accurately define the process of human movement, a limitation that causes data drift in the process of human body positioning, thus seriously affecting positioning accuracy and stability. The traditional pedestrian dead-reckoning algorithm, which is based on a single inertial measurement unit, can suppress the data drift, but fails to accurately calculate the number of walking steps and heading value, thus it cannot meet the application requirements. This study proposes an indoor dynamic positioning method with an error self-correcting function based on the symmetrical characteristics of human motion to obtain the definition basis of human motion process quickly and to solve the abovementioned problems. On the basis of this proposed method, an ultra-wide band (UWB) method is introduced. An unscented Kalman filter is applied to fuse inertial sensors and UWB data, inertial positioning is applied to compensation for the defects of susceptibility to UWB signal obstacles, and UWB positioning is used to overcome the error accumulation of inertial positioning. The above method can improve both the positioning accuracy and the response of the positioning results. Finally, this study designs an indoor positioning test system to test the static and dynamic performances of the proposed indoor positioning method. Results show that the positioning system both has high accuracy and good real-time performance. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2493 KiB

Open AccessArticle

Temperature Dependence of Faraday Effect-Induced Bias Error in a Fiber Optic Gyroscope

by Xuyou Li, Pan Liu, Xingxing Guang, Zhenlong Xu, Lianwu Guan and Guangchun Li

Sensors 2017, 17(9), 2046; https://doi.org/10.3390/s17092046 - 07 Sep 2017

Cited by 14 | Viewed by 5063

Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environments, such as magnetic field and temperature field variation, is necessary for its practical applications. This paper presents an investigation of Faraday effect-induced bias error of IFOG under varying temperature. Jones matrix [...] Read more.

Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environments, such as magnetic field and temperature field variation, is necessary for its practical applications. This paper presents an investigation of Faraday effect-induced bias error of IFOG under varying temperature. Jones matrix method is utilized to formulize the temperature dependence of Faraday effect-induced bias error. Theoretical results show that the Faraday effect-induced bias error changes with the temperature in the non-skeleton polarization maintaining (PM) fiber coil. This phenomenon is caused by the temperature dependence of linear birefringence and Verdet constant of PM fiber. Particularly, Faraday effect-induced bias errors of two polarizations always have opposite signs that can be compensated optically regardless of the changes of the temperature. Two experiments with a 1000 m non-skeleton PM fiber coil are performed, and the experimental results support these theoretical predictions. This study is promising for improving the bias stability of IFOG. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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7120 KiB

Open AccessArticle

An Adaptive Low-Cost INS/GNSS Tightly-Coupled Integration Architecture Based on Redundant Measurement Noise Covariance Estimation

by Zheng Li, Hai Zhang, Qifan Zhou and Huan Che

Sensors 2017, 17(9), 2032; https://doi.org/10.3390/s17092032 - 05 Sep 2017

Cited by 21 | Viewed by 5313

The main objective of the introduced study is to design an adaptive Inertial Navigation System/Global Navigation Satellite System (INS/GNSS) tightly-coupled integration system that can provide more reliable navigation solutions by making full use of an adaptive Kalman filter (AKF) and satellite selection algorithm. [...] Read more.

The main objective of the introduced study is to design an adaptive Inertial Navigation System/Global Navigation Satellite System (INS/GNSS) tightly-coupled integration system that can provide more reliable navigation solutions by making full use of an adaptive Kalman filter (AKF) and satellite selection algorithm. To achieve this goal, we develop a novel redundant measurement noise covariance estimation (RMNCE) theorem, which adaptively estimates measurement noise properties by analyzing the difference sequences of system measurements. The proposed RMNCE approach is then applied to design both a modified weighted satellite selection algorithm and a type of adaptive unscented Kalman filter (UKF) to improve the performance of the tightly-coupled integration system. In addition, an adaptive measurement noise covariance expanding algorithm is developed to mitigate outliers when facing heavy multipath and other harsh situations. Both semi-physical simulation and field experiments were conducted to evaluate the performance of the proposed architecture and were compared with state-of-the-art algorithms. The results validate that the RMNCE provides a significant improvement in the measurement noise covariance estimation and the proposed architecture can improve the accuracy and reliability of the INS/GNSS tightly-coupled systems. The proposed architecture can effectively limit positioning errors under conditions of poor GNSS measurement quality and outperforms all the compared schemes. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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4188 KiB

Open AccessArticle

An IMM-Aided ZUPT Methodology for an INS/DVL Integrated Navigation System

by Yiqing Yao, Xiaosu Xu and Xiang Xu

Sensors 2017, 17(9), 2030; https://doi.org/10.3390/s17092030 - 05 Sep 2017

Cited by 32 | Viewed by 5394

Inertial navigation system (INS)/Doppler velocity log (DVL) integration is the most common navigation solution for underwater vehicles. Due to the complex underwater environment, the velocity information provided by DVL always contains some errors. To improve navigation accuracy, zero velocity update (ZUPT) technology is [...] Read more.

Inertial navigation system (INS)/Doppler velocity log (DVL) integration is the most common navigation solution for underwater vehicles. Due to the complex underwater environment, the velocity information provided by DVL always contains some errors. To improve navigation accuracy, zero velocity update (ZUPT) technology is considered, which is an effective algorithm for land vehicles to mitigate the navigation error during the pure INS mode. However, in contrast to ground vehicles, the ZUPT solution cannot be used directly for underwater vehicles because of the existence of the water current. In order to leverage the strengths of the ZUPT method and the INS/DVL solution, an interactive multiple model (IMM)-aided ZUPT methodology for the INS/DVL-integrated underwater navigation system is proposed. Both the INS/DVL and INS/ZUPT models are constructed and operated in parallel, with weights calculated according to their innovations and innovation covariance matrices. Simulations are conducted to evaluate the proposed algorithm. The results indicate that the IMM-aided ZUPT solution outperforms both the INS/DVL solution and the INS/ZUPT solution in the underwater environment, which can properly distinguish between the ZUPT and non-ZUPT conditions. In addition, during DVL outage, the effectiveness of the proposed algorithm is also verified. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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3804 KiB

Open AccessArticle

Investigation on Eigenfrequency of a Cylindrical Shell Resonator under Resonator-Top Trimming Methods

by Kai Zeng, Youwang Hu, Guiling Deng, Xiaoyan Sun, Wenyi Su, Yunpeng Lu and Ji’an Duan

Sensors 2017, 17(9), 2011; https://doi.org/10.3390/s17092011 - 02 Sep 2017

Cited by 15 | Viewed by 4788

The eigenfrequency of a resonator plays a significant role in the operation of a cylindrical shell vibrating gyroscope, and trimming is aimed at eliminating the frequency split that is the difference of eigenfrequency between two work modes. In this paper, the effects on [...] Read more.

The eigenfrequency of a resonator plays a significant role in the operation of a cylindrical shell vibrating gyroscope, and trimming is aimed at eliminating the frequency split that is the difference of eigenfrequency between two work modes. In this paper, the effects on eigenfrequency under resonator-top trimming methods that trim the top of the resonator wall are investigated by simulation and experiments. Simulation results show that the eigenfrequency of the trimmed mode increases in the holes-trimming method, whereas it decreases in the grooves-trimming method. At the same time, the untrimmed modes decrease in both holes-trimming and grooves-trimming methods. Moreover, grooves-trimming is more efficient than holes-trimming, which indicates that grooves-trimming can be a primary trimming method, and holes-trimming can be a precision trimming method. The rigidity condition after grooves-trimming is also studied to explain the variation of eigenfrequency. A femtosecond laser is employed in the resonator trimming experiment by the precise ablation of the material. Experimental results are in agreement with the simulation results. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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11553 KiB

Open AccessArticle

An Extended Kalman Filter-Based Attitude Tracking Algorithm for Star Sensors

by Jian Li, Xinguo Wei and Guangjun Zhang

Sensors 2017, 17(8), 1921; https://doi.org/10.3390/s17081921 - 21 Aug 2017

Cited by 24 | Viewed by 6933

Efficiency and reliability are key issues when a star sensor operates in tracking mode. In the case of high attitude dynamics, the performance of existing attitude tracking algorithms degenerates rapidly. In this paper an extended Kalman filtering-based attitude tracking algorithm is presented. The [...] Read more.

Efficiency and reliability are key issues when a star sensor operates in tracking mode. In the case of high attitude dynamics, the performance of existing attitude tracking algorithms degenerates rapidly. In this paper an extended Kalman filtering-based attitude tracking algorithm is presented. The star sensor is modeled as a nonlinear stochastic system with the state estimate providing the three degree-of-freedom attitude quaternion and angular velocity. The star positions in the star image are predicted and measured to estimate the optimal attitude. Furthermore, all the cataloged stars observed in the sensor field-of-view according the predicted image motion are accessed using a catalog partition table to speed up the tracking, called star mapping. Software simulation and night-sky experiment are performed to validate the efficiency and reliability of the proposed method. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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1892 KiB

Open AccessArticle

Characteristics of Marine Gravity Anomaly Reference Maps and Accuracy Analysis of Gravity Matching-Aided Navigation

by Hubiao Wang, Lin Wu, Hua Chai, Yaofei Xiao, Houtse Hsu and Yong Wang

Sensors 2017, 17(8), 1851; https://doi.org/10.3390/s17081851 - 10 Aug 2017

Cited by 32 | Viewed by 5643

The variation of a marine gravity anomaly reference map is one of the important factors that affect the location accuracy of INS/Gravity integrated navigation systems in underwater navigation. In this study, based on marine gravity anomaly reference maps, new characteristic parameters of the [...] Read more.

The variation of a marine gravity anomaly reference map is one of the important factors that affect the location accuracy of INS/Gravity integrated navigation systems in underwater navigation. In this study, based on marine gravity anomaly reference maps, new characteristic parameters of the gravity anomaly were constructed. Those characteristic values were calculated for 13 zones (105°–145° E, 0°–40° N) in the Western Pacific area, and simulation experiments of gravity matching-aided navigation were run. The influence of gravity variations on the accuracy of gravity matching-aided navigation was analyzed, and location accuracy of gravity matching in different zones was determined. Studies indicate that the new parameters may better characterize the marine gravity anomaly. Given the precision of current gravimeters and the resolution and accuracy of reference maps, the location accuracy of gravity matching in China’s Western Pacific area is ~1.0–4.0 nautical miles (n miles). In particular, accuracy in regions around the South China Sea and Sulu Sea was the highest, better than 1.5 n miles. The gravity characteristic parameters identified herein and characteristic values calculated in various zones provide a reference for the selection of navigation area and planning of sailing routes under conditions requiring certain navigational accuracy. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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2567 KiB

Open AccessArticle

Angular Rate Sensing with GyroWheel Using Genetic Algorithm Optimized Neural Networks

by Yuyu Zhao, Hui Zhao, Xin Huo and Yu Yao

Sensors 2017, 17(7), 1692; https://doi.org/10.3390/s17071692 - 22 Jul 2017

Cited by 13 | Viewed by 4484

GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular [...] Read more.

GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular rates. In this paper, the problem of angular rate sensing with the GyroWheel is investigated. Firstly, a simplified rate sensing equation is introduced, and the error characteristics of the method are analyzed. According to the analysis results, a rate sensing principle based on torque balance theory is developed, and a practical way to estimate the angular rates within the whole operating range of GyroWheel is provided by using explicit genetic algorithm optimized neural networks. The angular rates can be determined by the measurable values of the GyroWheel (including tilt angles, spin rate and torque coil currents), the weights and the biases of the neural networks. Finally, the simulation results are presented to illustrate the effectiveness of the proposed angular rate sensing method with GyroWheel. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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5225 KiB

Open AccessArticle

A Damping Grid Strapdown Inertial Navigation System Based on a Kalman Filter for Ships in Polar Regions

by Weiquan Huang, Tao Fang, Li Luo, Lin Zhao and Fengzhu Che

Sensors 2017, 17(7), 1551; https://doi.org/10.3390/s17071551 - 03 Jul 2017

Cited by 23 | Viewed by 5857

The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing [...] Read more.

The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing the Schuler periodic oscillation is an effective way to enhance navigation accuracy. The Kalman filter based on the grid SINS error model which applies to the ship is established in this paper. The errors of grid-level attitude angles can be accurately estimated when the external velocity contains constant error, and then correcting the errors of the grid-level attitude angles through feedback correction can effectively dampen the Schuler periodic oscillation. The simulation results show that with the aid of external reference velocity, the proposed external level damping algorithm based on the Kalman filter can suppress the Schuler periodic oscillation effectively. Compared with the traditional external level damping algorithm based on the damping network, the algorithm proposed in this paper can reduce the overshoot errors when the state of grid SINS is switched from the non-damping state to the damping state, and this effectively improves the navigation accuracy of the system. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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20213 KiB

Open AccessArticle

Static and Dynamic Accuracy of an Innovative Miniaturized Wearable Platform for Short Range Distance Measurements for Human Movement Applications

by Stefano Bertuletti, Andrea Cereatti, Daniele Comotti, Michele Caldara and Ugo Della Croce

Sensors 2017, 17(7), 1492; https://doi.org/10.3390/s17071492 - 24 Jun 2017

Cited by 24 | Viewed by 6430

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. [...] Read more.

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF), allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i) target colors; (ii) sensor-target distances (up to 200 mm) and (iii) sensor-target angles of incidence (AoI) (up to

60^{\circ}

). Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black). Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to

0^{\circ}

, the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to

3.6

mm (static) and

11.9

mm (dynamic) for AoI equal to

\pm 30^{\circ}

, and up to

7.8

mm (static) and

25.6

mm (dynamic) for AoI equal to

\pm 60^{\circ}

. In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption, compared to existing technologies. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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Open AccessArticle

A Cost-Effective Vehicle Localization Solution Using an Interacting Multiple Model−Unscented Kalman Filters (IMM-UKF) Algorithm and Grey Neural Network

by Qimin Xu, Xu Li and Ching-Yao Chan

Sensors 2017, 17(6), 1431; https://doi.org/10.3390/s17061431 - 18 Jun 2017

Cited by 46 | Viewed by 6283

In this paper, we propose a cost-effective localization solution for land vehicles, which can simultaneously adapt to the uncertain noise of inertial sensors and bridge Global Positioning System (GPS) outages. First, three Unscented Kalman filters (UKFs) with different noise covariances are introduced into [...] Read more.

In this paper, we propose a cost-effective localization solution for land vehicles, which can simultaneously adapt to the uncertain noise of inertial sensors and bridge Global Positioning System (GPS) outages. First, three Unscented Kalman filters (UKFs) with different noise covariances are introduced into the framework of Interacting Multiple Model (IMM) algorithm to form the proposed IMM-based UKF, termed as IMM-UKF. The IMM algorithm can provide a soft switching among the three UKFs and therefore adapt to different noise characteristics. Further, two IMM-UKFs are executed in parallel when GPS is available. One fuses the information of low-cost GPS, in-vehicle sensors, and micro electromechanical system (MEMS)-based reduced inertial sensor systems (RISS), while the other fuses only in-vehicle sensors and MEMS-RISS. The differences between the state vectors of the two IMM-UKFs are considered as training data of a Grey Neural Network (GNN) module, which is known for its high prediction accuracy with a limited amount of samples. The GNN module can predict and compensate position errors when GPS signals are blocked. To verify the feasibility and effectiveness of the proposed solution, road-test experiments with various driving scenarios were performed. The experimental results indicate that the proposed solution outperforms all the compared methods. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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Open AccessArticle

An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM

by Changsheng Cai, Yangzhao Gong, Yang Gao and Cuilin Kuang

Sensors 2017, 17(6), 1302; https://doi.org/10.3390/s17061302 - 06 Jun 2017

Cited by 47 | Viewed by 5244

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. [...] Read more.

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. In this study, an approach is proposed to accelerate the single-frequency PPP convergence by combining quad-constellation global navigation satellite system (GNSS) and global ionospheric map (GIM) data. In this proposed approach, the GPS, GLONASS, BeiDou, and Galileo observations are directly used in an uncombined observation model and as a result the ionospheric and hardware delay (IHD) can be estimated together as a single unknown parameter. The IHD values acquired from the GIM product and the multi-GNSS differential code bias (DCB) product are then utilized as pseudo-observables of the IHD parameter in the observation model. A time varying weight scheme has also been proposed for the pseudo-observables to gradually decrease its contribution to the position solutions during the convergence period. To evaluate the proposed approach, datasets from twelve Multi-GNSS Experiment (MGEX) stations on seven consecutive days are processed and analyzed. The numerical results indicate that the single-frequency PPP with quad-constellation GNSS and GIM data are able to reduce the convergence time by 56%, 47%, 41% in the east, north, and up directions compared to the GPS-only single-frequency PPP. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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Review

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4744 KiB

Open AccessReview

Research and Development of Electrostatic Accelerometers for Space Science Missions at HUST

by Yanzheng Bai, Zhuxi Li, Ming Hu, Li Liu, Shaobo Qu, Dingyin Tan, Haibo Tu, Shuchao Wu, Hang Yin, Hongyin Li and Zebing Zhou

Sensors 2017, 17(9), 1943; https://doi.org/10.3390/s17091943 - 23 Aug 2017

Cited by 44 | Viewed by 8263

High-precision electrostatic accelerometers have achieved remarkable success in satellite Earth gravity field recovery missions. Ultralow-noise inertial sensors play important roles in space gravitational wave detection missions such as the Laser Interferometer Space Antenna (LISA) mission, and key technologies have been verified in the [...] Read more.

High-precision electrostatic accelerometers have achieved remarkable success in satellite Earth gravity field recovery missions. Ultralow-noise inertial sensors play important roles in space gravitational wave detection missions such as the Laser Interferometer Space Antenna (LISA) mission, and key technologies have been verified in the LISA Pathfinder mission. Meanwhile, at Huazhong University of Science and Technology (HUST, China), a space accelerometer and inertial sensor based on capacitive sensors and the electrostatic control technique have also been studied and developed independently for more than 16 years. In this paper, we review the operational principle, application, and requirements of the electrostatic accelerometer and inertial sensor in different space missions. The development and progress of a space electrostatic accelerometer at HUST, including ground investigation and space verification are presented. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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