Pseudorange error prediction for adaptive tightly coupled GNSS/IMU navigation in urban areas

The integration between Global Navigation Satellite System (GNSS) and on-board sensors is widely used for vehicle positioning. However, as the main information source in the integration, the positioning performance of single- or multiconstellation GNSSs is severely degraded in urban canyons due to the effects of Non-Line-Of-Sight (NLOS) and multipath propagations. How to mitigate such effects is vital to achieve accurate positioning performance in urban canyons. This paper proposes a tightly coupled positioning solution for land vehicles, fusing dual-constellation GNSSs with other low-cost complementary sensors. First, the nonlinear filter model is established based on a cost-effective reduced inertial sensor system with 3D navigation solution. Then, an adaptive fuzzy unscented Kalman filter (AF-UKF) algorithm is developed to achieve the global fusion. In the implementation of AF-UKF, the fuzzy calibration logic (FCL) is designed and introduced to adaptively adjust the dependence on each received satellite measurement to effectively mitigate the NLOS and multipath interferences in urban areas. Finally, the proposed solution is evaluated through experiments. The results validate the feasibility and effectiveness of the proposed solution.

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Tightly-Coupled GNSS/Vision Using a Sky-Pointing Camera for Vehicle Navigation in Urban Areas

Sensors ◽

10.3390/s18041244 ◽

2018 ◽

Vol 18 (4) ◽

pp. 1244 ◽

Cited By ~ 8

Author(s):

Paul Gakne ◽

Kyle O’Keefe

Keyword(s):

Urban Areas ◽

Vehicle Navigation ◽

Tightly Coupled

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Research on Tightly Coupled Multi-Antenna GNSS/MEMS Single-Frequency Single-Epoch Attitude Determination in Urban Environment

Remote Sensing ◽

10.3390/rs13142710 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2710

Author(s):

Ming Gao ◽

Genyou Liu ◽

Shengliang Wang ◽

Gongwei Xiao ◽

Wenhao Zhao ◽

...

Keyword(s):

Success Rate ◽

Ambiguity Resolution ◽

Urban Areas ◽

Attitude Determination ◽

Integer Ambiguity ◽

Single Frequency ◽

Half Cycle ◽

Cycle Slips ◽

Tightly Coupled ◽

Single Epoch

GNSS-only attitude determination is difficult to perform well in poor-satellite-tracking environments such as urban areas with high and dense buildings or trees. In addition, it is harder to resolve integer ambiguity in the case of single-frequency single-epoch process mode. In this contribution, a low-cost MEMS gyroscope is integrated with multi-antenna GNSS to improve the performance of the attitude determination. A new tightly coupled (TC) model is proposed, which uses a single filter to achieve the optimal estimation of attitude drift, gyro biases and ambiguities. In addition, a MEMS-Attitude-aided Quality-Control method (MAQC) for GNSS observations is designed to eliminate both the carrier multipath errors and half-cycle slips disturbing ambiguity resolution. Vehicle experiments show that in GNSS-friendly scenarios, the Ambiguity Resolution (AR) success rate of the proposed model with MAQC can reach 100%, and the accuracy of attitudes are (0.12, 0.2, 0.2) degrees for heading, pitch and roll angles, respectively. Even in harsh scenarios, the AR success rate increases from about 67% for the GNSS only case to above 90% after coupling GNSS tightly with MEMS, and it is further improved to about 98% with MAQC. Meanwhile, the accuracy and continuity of attitude determination are effectively guaranteed.

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A Tightly Coupled BDS/INS Integrated Positioning Algorithm Based on Triple-Frequency Single-Epoch Observations

Mathematical Problems in Engineering ◽

10.1155/2021/6653625 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Fei Ye ◽

Shuguo Pan ◽

Wang Gao ◽

Hao Wang ◽

Chun Ma ◽

...

Keyword(s):

Urban Areas ◽

Carrier Phase ◽

Satellite System ◽

Integration Scheme ◽

Navigation Satellite ◽

Positioning Accuracy ◽

Triple Frequency ◽

Tightly Coupled ◽

Wide Lane ◽

Single Epoch

Vehicular dynamic positioning based on tightly coupled (TC) Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS) integration in urban areas is due to either low accuracy of pseudorange or poor continuity of carrier phase, resulting in insufficient positioning performance. To enhance the stability while ensuring positioning accuracy, this paper proposed a tightly coupled Beidou Navigation Satellite System (BDS)/INS integration scheme by improving measurement modelling with triple-frequency observations: first, a stepwise single-epoch ambiguity resolution of extra-wide-lane (EWL)/wide-lane (WL) combined observations and then modelling the measurement equation with fixed WL observation instead of conventional pseudorange or carrier phase. Experiments were carried out for verification with data collected in real traffic by a measurement vehicle. The proposed method achieved single-epoch output with an RMS statistical accuracy of decimetre level of 0.152 m horizontally and 0.196 m vertically. The signal outage experiment verified that the proposed algorithm is restoring high-accuracy positioning output in single-epoch once the signal is recaptured. The proposed method obtained a positioning accuracy improvement of 43.6% horizontally and 6.2% vertically in signal outage sections compared to the conventional method. This avoids the multiepoch ambiguity searching to fix with conventional carrier-phase processing, thereby improving the positioning stability.

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Management of minor ailments in primary schoolchildren in rural and urban areas

Child Care Health and Development ◽

10.1046/j.1365-2214.1996.787787.x ◽

1996 ◽

Vol 22 (3) ◽

pp. 167-174

Author(s):

J A Cantrill ◽

B Johannesson ◽

M Nicholson ◽

P R Noyce

Keyword(s):

Urban Areas ◽

Rural And Urban Areas ◽

Rural And Urban ◽

Primary Schoolchildren ◽

Minor Ailments

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Cannabis use in Switzerland: The role of attribution of drug use to friends, urbanization and repression 1The study was supported by the Swiss Federal Office of Public Health (Bundesamt für Gesundheit BAG) Grant 316.96.5980.

Swiss Journal of Psychology ◽

10.1024//1421-0185.60.2.99 ◽

2001 ◽

Vol 60 (2) ◽

pp. 99-107 ◽

Cited By ~ 7

Author(s):

Holger Schmid

Keyword(s):

Drug Use ◽

Urban Areas ◽

Hierarchical Linear Model ◽

Cannabis Use ◽

School Aged Children ◽

Structural Variables ◽

Hbsc Study ◽

Nationally Representative ◽

Highly Correlated ◽

Individual Use

Cannabis use does not show homogeneous patterns in a country. In particular, urbanization appears to influence prevalence rates, with higher rates in urban areas. A hierarchical linear model (HLM) was employed to analyze these structural influences on individuals in Switzerland. Data for this analysis were taken from the Switzerland survey of Health Behavior in School-Aged Children (HBSC) Study, the most recent survey to assess drug use in a nationally representative sample of 3473 15-year-olds. A total of 1487 male and 1620 female students indicated their cannabis use and their attributions of drug use to friends. As second level variables we included address density in the 26 Swiss Cantons as an indicator of urbanization and officially recorded offences of cannabis use in the Cantons as an indicator of repressive policy. Attribution of drug use to friends is highly correlated with cannabis use. The correlation is even more pronounced in urban Cantons. However, no association between recorded offences and cannabis use was found. The results suggest that structural variables influence individuals. Living in an urban area effects the attribution of drug use to friends. On the other hand repressive policy does not affect individual use.

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