scholarly journals Effect Analysis of GNSS/INS Processing Strategy for Sufficient Utilization of Urban Environment Observations

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 620
Author(s):  
Bo Shi ◽  
Mengke Wang ◽  
Yunpeng Wang ◽  
Yuntian Bai ◽  
Kang Lin ◽  
...  
Keyword(s):  
Urban Environment ◽  
Real Data ◽  
Satellite System ◽  
Urban Environments ◽  
Integrated System ◽  
Coupled Systems ◽  
Integer Ambiguity ◽  
Processing Strategy ◽  
Effect Analysis ◽  
Tightly Coupled

The occlusion of buildings in urban environments leads to the intermittent reception of satellite signals, which limits the utilization of observations. This subsequently results in a decline of the positioning and attitude accuracy of Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS) integrated system (GNSS/INS). This study implements a smooth post-processing strategy based on a tightly coupled differential GNSS/INS. Specifically, this strategy used the INS-estimated position to reinitialize integer ambiguity. The GNSS raw observations were input into the Kalman filter to update the measurement. The Rauch–Tung–Striebel smoothing (RTSS) algorithm was used to process the observations of the entire period. This study analyzed the performance of loosely coupled and tightly coupled systems in an urban environment and the improvement of the RTSS algorithm on the navigation solution from the perspective of fully mining the observations. The experimental results of the simulation data and real data show that, compared with the traditional tightly coupled processing strategy which does not use INS-aided integer ambiguity resolution and RTSS algorithm, the strategy in this study sufficiently utilized INS observations and GNSS observations to effectively improve the accuracy of positioning and attitude and ensure the continuity of navigation results in an obstructed environment.

Performance Comparison among Different Precise Satellite Ephemeris and Clock Products for PPP/INS/UWB Tightly Coupled Positioning

2017 ◽  
Vol 71 (3) ◽  
pp. 585-606 ◽  
Author(s):  
Zengke Li ◽  
Nanshan Zheng ◽  
Jian Wang ◽  
Jingxiang Gao
Keyword(s):  
Satellite System ◽  
Performance Comparison ◽  
Integrated System ◽  
Ultra Wideband ◽  
Position Resolution ◽  
Position Accuracy ◽  
Global Positioning ◽  
Accurate Performance ◽  
Tightly Coupled ◽  
Global Navigation Satellite

To meet the requirements of different applications, the International Global Navigation Satellite System (GNSS) Service (IGS) has provided Global Positioning System (GPS) satellite ephemerides and clock products with different accuracy levels (final, rapid and ultra-rapid products). Comparison of Precise Point Positioning/Inertial Navigation System/Ultra Wideband (PPP/INS/UWB) tightly coupled positioning with different precise satellite ephemeris and clock products is made and corresponding data analysis is provided. Final, rapid and ultra-rapid products are applied in a PPP/INS/UWB integrated system. The field trajectories, position and velocity errors of the integrated system with different products are compared. The results indicate that PPP/INS/UWB tightly coupled positioning with final and rapid products achieves an accurate performance. Compared with the position resolution using final products, the position accuracy with the ultra-rapid products (observed half) is slightly reduced and the position accuracy with the ultra-rapid products (predicted half) has a 0·1–0·2 m reduction. The influence of precise satellite ephemeris and clock products is very minor for non-real-time positioning, relative to the accuracy of PPP/INS/UWB tightly coupled positioning.

scholarly journals A Multi-Sensor Tight Fusion Method Designed for Vehicle Navigation

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2551 ◽  
Author(s):  
Qifeng Lai ◽  
Hong Yuan ◽  
Dongyan Wei ◽  
Ningbo Wang ◽  
Zishen Li ◽  
...  
Keyword(s):  
Navigation System ◽  
Rapid Development ◽  
Satellite System ◽  
Urban Environments ◽  
Sensor Technology ◽  
Vehicle Navigation ◽  
Noise Compensation ◽  
Vehicle Navigation System ◽  
Tightly Coupled ◽  
Global Navigation Satellite

Using the Global Navigation Satellite System (GNSS), it is difficult to provide continuous and reliable position service for vehicle navigation in complex urban environments, due to the natural vulnerability of the GNSS signal. With the rapid development of the sensor technology and the reduction in their costs, the positioning performance of GNSS is expected to be significantly improved by fusing multi-sensors. In order to improve the continuity and reliability of the vehicle navigation system, we proposed a multi-sensor tight fusion (MTF) method by combining the inertial navigation system (INS), odometer, and barometric altimeter with the GNSS technique. Different fusion strategies were presented in the open-sky, insufficient satellite, and satellite outage environments to check the performance improvement of the proposed method. The simulation and real-device tests demonstrate that in the open-sky context, the error of sensors can be estimated correctly. This is useful for sensor noise compensation and position accuracy improvement, when GNSS is unavailable. In the insufficient satellite context (6 min), with the help of the barometric altimeter and a clock model, the accuracy of the method can be close to that in the open-sky context. In the satellite outage context, the error divergence of the MTF is obviously slower than the traditional GNSS/INS tightly coupled integration, as seen by odometer and barometric altimeter assisting.

scholarly journals Feature-Aided RTK/LiDAR/INS Integrated Positioning System with Parallel Filters in the Ambiguity-Position-Joint Domain for Urban Environments

2021 ◽  
Vol 13 (10) ◽  
pp. 2013
Author(s):  
Wenyi Li ◽  
Gang Liu ◽  
Xiaowei Cui ◽  
Mingquan Lu
Keyword(s):  
Satellite System ◽  
Urban Environments ◽  
Integrated System ◽  
Integrated Systems ◽  
Loose Coupling ◽  
Positioning Precision ◽  
Cycle Slips ◽  
Global Positioning ◽  
Coupling Mode ◽  
Global Navigation Satellite

As the modern navigation business evolves, demands for high-precision positioning in GNSS-challenged environments increase, and the integrated system composed of Global Navigation Satellite System (GNSS)-based Real-Time Kinematic (RTK), inertial system (INS), Light Detection and Ranging (LiDAR), etc., is accepted as the most feasible solution to the issue. For prior-map-free situations, as the only sensor with a global frame, RTK determines and maintains the global positioning precision of the integrated system. However, RTK performance degrades greatly in GNSS-challenged environments, and most of the existing integrated systems adopt loose coupling mode, which does nothing to improve RTK and, thus, prevents integrated systems from further improvement. Aiming at improving RTK performance in the RTK/LiDAR/INS integrated system, we proposed an innovative integrated algorithm that utilizes RTK to register LiDAR features while integrating the pre-registered LiDAR features to RTK and adopts parallel filters in the ambiguity-position-joint domain to weaken the effects of low satellite availability, cycle slips, and multipath. By doing so, we can improve the RTK fix rate and stability in GNSS-challenged environments. The results of the theoretical analyses, simulation experiments, and a road test proved that the proposed method improved RTK performance in GNSS-challenged environments and, thus, guaranteed the global positioning precision of the whole system.

scholarly journals A Robust Adaptive Cubature Kalman Filter Based on SVD for Dual-Antenna GNSS/MIMU Tightly Coupled Integration

2021 ◽  
Vol 13 (10) ◽  
pp. 1943
Author(s):  
Cheng Pan ◽  
Nijia Qian ◽  
Zengke Li ◽  
Jingxiang Gao ◽  
Zhenbin Liu ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Kalman Filter ◽  
Satellite System ◽  
Integrated System ◽  
Measurement Unit ◽  
Attitude Angle ◽  
Cubature Kalman Filter ◽  
Tightly Coupled ◽  
Heading Angle ◽  
Robust Adaptive

In complex urban environments, a single Global Navigation Satellite System (GNSS) is often not ideal for navigation due to a lack of sufficient visible satellites. Additionally, the heading angle error of a GNSS/micro-electro-mechanical system–grade inertial measurement unit (MIMU) tightly coupled integration based on the single antenna is large, and the attitude angle, velocity, and position calculated therein all have large errors. Considering the above problems, this paper designs a tightly coupled integration of GNSS/MIMU based on two GNSS antennas and proposes a singular value decomposition (SVD)-based robust adaptive cubature Kalman filter (SVD-RACKF) according to the model characteristics of the integration. In this integration, the high-accuracy heading angle of the carrier is obtained through two antennas, and the existing attitude angle information is used as the observation to constrain the filtering estimation. The proposed SVD-RACKF uses SVD to stabilize the numerical accuracy of the recursive filtering. Furthermore, the three-stage equivalent weight function and the adaptive adjustment factor are constructed to suppress the influence of the gross error and the abnormal state on the parameter estimation, respectively. A set of real measured data was employed for testing and analysis. The results show that dual antennas and dual systems can improve the positioning performance of the integrated system to a certain extent, and the proposed SVD-RACKF can accurately detect the gross errors of the observations and effectively suppress them. Compared with the cubature Kalman filter, the proposed filtering algorithm is more robust, with higher accuracy and reliability of parameter estimation.

Evaluation for Vehicle Positioning in Urban Environment Using QZSS Enhancement Function

2012 ◽  
Vol 24 (5) ◽  
pp. 894-901
Author(s):  
Mitsunori Kitamura ◽  
◽  
Taro Suzuki ◽  
Yoshiharu Amano ◽  
Takumi Hashizume ◽  
...  
Keyword(s):  
Urban Environment ◽  
Performance Enhancement ◽  
Elevation Angle ◽  
Satellite System ◽  
High Elevation ◽  
Urban Environments ◽  
Gps Positioning ◽  
Positioning Errors ◽  
Evaluation Test ◽  
Gps Accuracy

In this paper, we have evaluated the performance and availability enhancement of Quasi-Zenith Satellite System (QZSS) in urban environments. In urban environments, QZSS can be expected to be fairly effective because of the high elevation angle of satellite and enhancement functions. Therefore, we conducted performance and availability enhancement evaluation tests to verify thus. In performance enhancement evaluation test, in order to evaluate the improvement of GPS accuracy by L1 Submeter-class Augmentation with Integrity Function (L1-SAIF) broadcasted by QZSS satellite, we compared the positioning errors of only GPS positioning and L1-SAIF positioning in open sky environment. In availability enhancement evaluation test, we performed the static and kinematic observation test. In static observation test, in order to evaluate the improvement of GPS accuracy by availability enhancement, we observed GPS and QZSS statically in narrow-sky environment. And we compared the positioning errors of only GPS positioning and positioning using availability enhancement. In kinematic observation test, in order to evaluate the availability of QZSS based on the visibility of QZSS satellite in urban environment, we observed QZSS and SBAS from moving vehicle. And we compared the visibility of QZSS and SBAS satellites. From these evaluation tests, it was confirmed that the performance and availability enhancement of QZSS have high availability and effectiveness.

scholarly journals Precise and Robust RTK-GNSS Positioning in Urban Environments with Dual-Antenna Configuration

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3586 ◽  
Author(s):  
Fan ◽  
Li ◽  
Cui ◽  
Lu
Keyword(s):  
Urban Areas ◽  
Attitude Determination ◽  
Real Data ◽  
Satellite System ◽  
Urban Environments ◽  
Multiple Antenna ◽  
Gnss Positioning ◽  
Single Antenna ◽  
Gnss Measurements ◽  
Global Navigation Satellite

Robust and centimeter-level Real-time Kinematic (RTK)-based Global Navigation Satellite System (GNSS) positioning is of paramount importance for emerging GNSS applications, such as drones and automobile systems. However, the performance of conventional single-rover RTK degrades greatly in urban environments due to signal blockage and strong multipath. The increasing use of multiple-antenna/rover configurations for attitude determination in the above precise positioning applications, just as well, allows more information involved to improve RTK positioning performance in urban areas. This paper proposes a dual-antenna constraint RTK algorithm, which combines GNSS measurements of both antennas by making use of the geometric constraint between them. By doing this, the reception diversity between two antennas can be taken advantage of to improve the availability and geometric distribution of GNSS satellites, and what is more, the redundant measurements from a second antenna help to weaken the multipath effect on the first antenna. Particularly, an Ambiguity Dilution of Precision (ADOP)-based analysis is carried out to explore the intrinsic model strength for ambiguity resolution (AR) with different kinds of constraints. Based on the results, a Dual-Antenna with baseline VEctor Constraint algorithm (RTK) is developed. The primary advantages of the reported method include: 1) Improved availability and success rate of RTK, even if neither of the two single-antenna receivers can successfully solve the AR problem; and 2) reduced computational burden by adopting the concept of measurement projection. Simulated and real data experiments are performed to demonstrate robustness and precision of the algorithm in GNSS-challenged environments.

scholarly journals Measurement Strategies for Street-Level SLAM Laser Scanning of Urban Environments

2020 ◽  
Vol 27 (1) ◽  
pp. 1-19
Author(s):  
Aino Keitaanniemi ◽  
Antero Kukko ◽  
Juho-Pekka Virtanen ◽  
Matti T. Vaaja
Keyword(s):  
Urban Environment ◽  
Laser Scanning ◽  
Point Clouds ◽  
Satellite System ◽  
Urban Environments ◽  
Measurement Unit ◽  
Street Level ◽  
Measurement Strategy ◽  
Laser Scanners ◽  
Measurement Strategies

Data collection for street-level mapping is currently executed with terrestrial (TLS) or mobile laser scanners (MLS). However, these methods have disadvantages such as TLS requiring a lot of time and MLS being dependent on the global navigation satellite system (GNSS) and an inertial measurement unit (IMU). These are not problems if we use simultaneous localization and mapping (SLAM) based laser scanners. We studied the utility of a SLAM ZEB-REVO scanner for mapping street-level objects in an urban environment by analyzing the geometric and visual differences with a TLS reference. In addition to this, we examined the influence of traffic on the measurement strategy. The results of the study showed that SLAM-based laser scanners can be used for street-level mapping. However, the measurement strategy affects the point clouds. The strategy of walking trajectory in loops produced a 2 cm RMS and 4-6 mm mode of error even in not optimal situations of the sensor in the urban environment. However, it was possible to get an RMS under 2.2 cm and a 32 cm mode of error with other measurement strategies.

Relationships

2018 ◽  
Author(s):  
Philip James
Keyword(s):  
Urban Environment ◽  
Companion Animals ◽  
Domestic Animals ◽  
Urban Environments ◽  
Select Group ◽  
Exotic Pets

Relationships between organisms within urban environments are many and varied. Plants are found in many households, and in addition to the benefits derived from their decorative properties, they also purify the air by removing pollutants. Over the course of history some animals have become domesticated: cows, horses, goats, providing food and transport. Of these, a select group have become companions (cats, dogs, and more exotic pets). Such domesticated and companion animals are an important part of the overall biology of urban environments and these relationships are explored and discussed. Some former companion or domestic animals have become feral, and other animals have never been domesticated and live freely in the urban environment. Some of these animals have beneficial relationships with humans whereas others are parasitic or are considered pests. These relationships are the focus for the later part of the exploration set out in this chapter.

What is the urban environment and what is biology?

2018 ◽  
Author(s):  
Philip James
Keyword(s):  
Urban Environment ◽  
Urban Environments ◽  
First Century ◽  
Final Part ◽  
Global Spread ◽  
Twenty First Century ◽  
Genes To Ecosystems ◽  
Micro Organisms ◽  
Initial Focus

The two main themes contained within the title The Biology of Urban Environments are explored. The initial focus is on urban environments. A discussion of the origins of cities and the global spread of urbanization leads on to a consideration of urban environments in the twenty-first century. In the second section, the focus switches to biology. The scope of the discipline is set out in terms of both the range of sub-disciplines and of biological scales. It is established from this discussion that in this book the topics considered span from genes to ecosystems and will be illustrated by examples of the biology of micro-organisms, plants, and animals. Importantly humans will be included within this consideration: our biology is affected by urban environments. The final part presents the structure of the book.

scholarly journals Revealing the Challenges of Smart Rainwater Harvesting for Integrated and Digital Resilience of Urban Water Infrastructure

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1902
Author(s):  
Martin Oberascher ◽  
Aun Dastgir ◽  
Jiada Li ◽  
Sina Hesarkazzazi ◽  
Mohsen Hajibabaei ◽  
...  
Keyword(s):  
Large Scale ◽  
Rainwater Harvesting ◽  
Data Communication ◽  
Integrated System ◽  
Coupled Systems ◽  
Urban Resilience ◽  
System Failures ◽  
Household Level ◽  
Performance Improvements ◽  
Smart Water

Smart rainwater harvesting (RWH) systems can automatically release stormwater prior to rainfall events to increase detention capacity on a household level. However, impacts and benefits of a widespread implementation of these systems are often unknown. This works aims to investigate the effect of a large-scale implementation of smart RWH systems on urban resilience by hypothetically retrofitting an Alpine municipality with smart rain barrels. Smart RWH systems represent dynamic systems, and therefore, the interaction between the coupled systems RWH units, an urban drainage network (UDN) and digital infrastructure is critical for evaluating resilience against system failures. In particular, digital parameters (e.g., accuracy of weather forecasts, or reliability of data communication) can differ from an ideal performance. Therefore, different digital parameters are varied to determine the range of uncertainties associated with smart RWH systems. As the results demonstrate, smart RWH systems can further increase integrated system resilience but require a coordinated integration into the overall system. Additionally, sufficient consideration of digital uncertainties is of great importance for smart water systems, as uncertainties can reduce/eliminate gained performance improvements. Moreover, a long-term simulation should be applied to investigate resilience with digital applications to reduce dependence on boundary conditions and rainfall patterns.

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