Low-Cost Real-Time PPP/INS Integration for Automated Land Vehicles

The last decade has witnessed a growing demand for precise positioning in many applications including car navigation. Navigating automated land vehicles requires at least sub-meter level positioning accuracy with the lowest possible cost. The Global Navigation Satellite System (GNSS) Single-Frequency Precise Point Positioning (SF-PPP) is capable of achieving sub-meter level accuracy in benign GNSS conditions using low-cost GNSS receivers. However, SF-PPP alone cannot be employed for land vehicles due to frequent signal degradation and blockage. In this paper, real-time SF-PPP is integrated with a low-cost consumer-grade Inertial Navigation System (INS) to provide a continuous and precise navigation solution. The PPP accuracy and the applied estimation algorithm contributed to reducing the effects of INS errors. The system was evaluated through two road tests which included open-sky, suburban, momentary outages, and complete GNSS outage conditions. The results showed that the developed PPP/INS system maintained horizontal sub-meter Root Mean Square (RMS) accuracy in open-sky and suburban environments. Moreover, the PPP/INS system could provide a continuous real-time positioning solution within the lane the vehicle is moving in. This lane-level accuracy was preserved even when passing under bridges and overpasses on the road. The developed PPP/INS system is expected to benefit low-cost precise land vehicle navigation applications including level 2 of vehicle automation which comprises services such as lane departure warning and lane-keeping assistance.

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Precise Single-Frequency Positioning Using Low-Cost Receiver with the Aid of Lane-Level Map Matching for Land Vehicle Navigation

Journal of Navigation ◽

10.1017/s0373463320000375 ◽

2020 ◽

pp. 1-14

Author(s):

Fei Liu ◽

Yue Liu ◽

Zhixi Nie ◽

Yang Gao

Keyword(s):

Low Cost ◽

Digital Camera ◽

Satellite System ◽

Single Frequency ◽

Map Matching ◽

Digital Map ◽

The Road ◽

Ambiguity Fixing ◽

Wide Range ◽

Global Navigation Satellite

Precise positioning with low-cost single-frequency global navigation satellite system (GNSS) receivers has great potential in a wide range of applications because of its low price and improved accuracy. However, challenges remain in achieving reliable and accurate solutions using low-cost receivers. For instance, the successful ambiguity fixing rate could be low for real-time kinematic (RTK) while large errors may occur in precise point positioning (PPP) in some scenarios (e.g., trees along the road). To solve the problems, this paper proposes a method with the aid of additional lane-level digital map information to improve the accuracy and reliability of RTK and PPP solutions. In the method, a digital camera will be applied for lane recognition and the positioning solution from a low-cost receiver will be projected to the digital map lane link. With the projected point position as a constraint, the RTK ambiguity fixing rate and PPP performance can be enhanced. A field kinematic test was conducted to verify the improvement of the RTK and PPP solutions with the aid of map matching. The results show that the RTK ambiguity fixing rate can be increased and the PPP positioning error can be reduced by map matching.

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Gauss process regression for real-time ionospheric delay estimation from GNSS observations

Acta Geodaetica et Geophysica ◽

10.1007/s40328-021-00368-y ◽

2022 ◽

Author(s):

Balazs Lupsic ◽

Bence Takacs

Keyword(s):

Real Time ◽

Low Cost ◽

Autonomous Vehicle ◽

Satellite System ◽

Ionospheric Delay ◽

Single Frequency ◽

Gauss Process ◽

Global Navigation Satellite ◽

Autonomous Vehicle Navigation ◽

Gnss Observations

AbstractThe number of devices equipped with global satellite positioning has exceeded seven billion recently. There are a wide variety of receivers regarding their accuracy and reliability. Low cost, multi-frequency units have been released on the market latterly; however, the number of single-frequency receivers is still significant. Since their measurements are influenced by ionospheric delay, accurate ionosphere models are of utmost importance to reduce the effect. This paper summarizes how Gauss process regression (GPR) can be applied to derive near real-time regional ionosphere models using raw Global Navigation Satellite System (GNSS) observations of permanent stations. While Gauss process is widely used in machine learning, GPR is a nonparametric, Bayesian approach to regression. GPR has several benefits for ionosphere monitoring since it is quite robust and efficient to derive a grid model from data available in irregular set of ionospheric pierce points. The corresponding instrumental delays are estimated by a parallel Kalman filter. The presented algorithm can be applied near real-time, however the results are offline calculated and are compared to two high quality TEC map products. Based on the analysis, the accuracy of the GPR modell is in 2 TECu range. The developed methods could be efficiently applied in the field of autonomous vehicle navigation with meeting both accuracy and integrity requirements.

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Kinematic PPP Using Mixed GPS/Glonass Single-Frequency Observations

Artificial Satellites ◽

10.2478/arsa-2019-0008 ◽

2019 ◽

Vol 54 (3) ◽

pp. 97-112

Author(s):

Mostafa Hamed ◽

Ashraf Abdallah ◽

Ashraf Farah

Keyword(s):

Low Cost ◽

Satellite System ◽

Single Frequency ◽

Future Research ◽

Frequency Data ◽

Dual Frequency ◽

Trajectory Data ◽

Average Improvement ◽

Kinematic Ppp ◽

Global Navigation Satellite

Abstract Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Single-frequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-frequency, GPS/GLONASS GNSS receiver and single-frequency data have been processed. Net_Diff software was used for processing all the data. The results have been compared with a reference solution. Adding GLONASS satellites significantly improved the satellite number and Position Dilution Of Precision (PDOP) value and accordingly improved the accuracy of positioning. In the case of “ADIS” data, the 3D Root Mean Square Error (RMSE) ranged between 0.273 and 0.816 m for GPS only and improved to a range from 0.256 to 0.550 m for GPS/GLONASS for the 6 processed days. An average improvement ratio of 24%, 29%, 30%, and 29% in the east, north, height, and 3D position components, respectively, was achieved. For the kinematic trajectory, the 3D position RMSE improved from 0.733 m for GPS only to 0.638 m for GPS/GLONASS. The improvement ratios were 7%, 5%, 28%, and 13% in the east, north, height, and 3D position components, respectively, for the kinematic trajectory data. This opens the way to add observations from the other two constellations (Galileo and BeiDou) for more accuracy in future research.

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Implementation and Analysis of Tightly Coupled Global Navigation Satellite System Precise Point Positioning/Inertial Navigation System (GNSS PPP/INS) with Insufficient Satellites for Land Vehicle Navigation

Sensors ◽

10.3390/s18124305 ◽

2018 ◽

Vol 18 (12) ◽

pp. 4305 ◽

Cited By ~ 8

Author(s):

Yue Liu ◽

Fei Liu ◽

Yang Gao ◽

Lin Zhao

Keyword(s):

Low Cost ◽

Satellite System ◽

Single Frequency ◽

Vehicle Navigation ◽

Land Vehicle ◽

Land Vehicle Navigation ◽

Gps Satellites ◽

Tightly Coupled ◽

Gnss Measurements ◽

Global Navigation Satellite

This paper implements and analyzes a tightly coupled single-frequency global navigation satellite system precise point positioning/inertial navigation system (GNSS PPP/INS) with insufficient satellites for land vehicle navigation using a low-cost GNSS receiver and a microelectromechanical system (MEMS)-based inertial measurement unit (IMU). For land vehicle navigation, it is inevitable to encounter the situation where insufficient satellites can be observed. Therefore, it is necessary to analyze the performance of tightly coupled integration in a GNSS-challenging environment. In addition, it is also of importance to investigate the least number of satellites adopted to improve the performance, compared with no satellites used. In this paper, tightly coupled integration using low-cost sensors with insufficient satellites was conducted, which provided a clear view of the improvement of the solution with insufficient satellites compared to no GNSS measurements at all. Specifically, in this paper single-frequency PPP was implemented to achieve the best performance, with one single-frequency receiver. The INS mechanization was conducted in a local-level frame (LLF). An extended Kalman filter was applied to fuse the two different types of measurements. To be more specific, in PPP processing, the atmosphere errors are corrected using a Saastamoinen model and the Center for Orbit Determination in Europe (CODE) global ionosphere map (GIM) product. The residuals of atmosphere errors are not estimated to accelerate the ambiguity convergence. For INS error mitigation, velocity constraints for land vehicle navigation are adopted to limit the quick drift of a MEMS-based IMU. Field tests with simulated partial and full GNSS outages were conducted to show the performance of tightly coupled GNSS PPP/INS with insufficient satellites: The results were classified as long-term (several minutes) and short-term (less than 1 min). The results showed that generally, with GNSS measurements applied, although the number of satellites was not enough, the solution still could be improved, especially with more than three satellites observed. With three GPS satellites used, the horizontal drift could be reduced to a few meters after several minutes. The 3D position error could be limited within 10 m in one minute when three GPS satellites were applied. In addition, a field test in an urban area where insufficient satellites were observed from time to time was also conducted to show the limited solution drift.

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Precise Point Positioning Algorithm for Pseudolite Combined with GNSS in a Constrained Observation Environment

Sensors ◽

10.3390/s20041120 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1120 ◽

Cited By ~ 1

Author(s):

Chuanzhen Sheng ◽

Xingli Gan ◽

Baoguo Yu ◽

Jingkui Zhang

Keyword(s):

High Precision ◽

Global Navigation Satellite System ◽

Low Cost ◽

Estimation Algorithm ◽

Satellite System ◽

Navigation Satellite ◽

Global Navigation ◽

Point Positioning ◽

Global Navigation Satellite ◽

Better Than

In urban canyon environments, Global Navigation Satellite System (GNSS) satellites are heavily obstructed with frequent rise and fall and severe multi-path errors induced by signal reflection, making it difficult to acquire precise, continuous, and reliable positioning information. To meet imperative demands for high-precision positioning of public users in complex environments, like urban canyons, and to solve the problems for GNSS/pseudolite positioning under these circumstances, the Global Navigation Satellite System (GNSS) Precision Point Positioning (PPP) algorithm combined with a pseudolite (PLS) was introduced. The former problems with the pseudolite PPP technique with distributed pseudo-satellites, which relies heavily on known points for initiation and prerequisite for previous high-precision time synchronization, were solved by means of a real-time equivalent clock error estimation algorithm, ambiguity fixing, and validation method. Experiments based on a low-cost receiver were performed, and the results show that in a weak obstructed environment with low-density building where the number of GNSS satellites was greater than seven, the accuracy of pseudolite/GNSS PPP with fixed ambiguity was better than 0.15 m; when there were less than four GNSS satellites in severely obstructed circumstances, it was impossible to obtain position by GNSS alone, but with the support of a pseudolite, the accuracy of PPP was able to be better than 0.3 m. Even without GNSS, the accuracy of PPP could be better than 0.5 m with only four pseudolites. The pseudolite/GNSS PPP algorithm presented in this paper can effectively improve availability with less GNSS or even without GNSS in constrained environments, like urban canyons in cities.

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Is GNSS real-time positioning a reliable option to validate erosion studies at olive grove environments?

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2020182-15752 ◽

2020 ◽

Vol 18 (2) ◽

pp. e0204

Author(s):

María S. Garrido-Carretero ◽

María I. Ramos-Galán ◽

María C. De Lacy-Pérez de los Cobos ◽

Sergio Blanca-Mena ◽

Antonio J. Gil-Cruz

Keyword(s):

Low Cost ◽

Satellite System ◽

Single Frequency ◽

Olive Grove ◽

Dual Frequency ◽

Significance Level ◽

Digital Elevation ◽

Significant Difference ◽

Spatial Redistribution ◽

Global Navigation Satellite

Aim of study: Soil degradation in agricultural areas is a widespread problem. In this framework, a data validation methodology is presented, including a study of the spatial resolution of Global Navigation Satellite System (GNSS) measurements, the calculation of erosion/deposition models, and the contribution of dual frequency and low-cost single frequency GNSS receivers.Area of study: A test olive grove in SE Spain.Material and methods: The study is based on three observation campaigns, between 2016 and 2018, using different GNSS receivers and working modes. The comparison between different surveys provide the volumetric variation over the analyzed period.Main results: Considering the dual-frequency receiver, there was no statistically significant difference between the means and the variances from 1.5 m and from 4.5 m data resolution at the 0.05 significance level. In order to estimate vertical differences from successive GNSS campaigns a differential digital elevation approach was applied. Although the differences depended on the zone of the test area and they changed along the monitoring period, the erosion rate could be catalogued as very low. The dual-frequency receiver satisfied the vertical centimetric precision limits for high accurate Digital Elevation Model (DEM), making it a reliable and accurate option to validate erosion studies in small areas.Research highlights: The results have allowed the characterization of multi-annual spatial redistribution of the topsoil at local scale, being of great help to design future prevention actions for the “tillage erosion” in olive grove environments. However, more tests are needed to guarantee the feasibility of low-cost receivers.

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Real-Time Driver Alert System Using Raspberry Pi

ECTI Transactions on Electrical Engineering, Electronics, and Communications ◽

10.37936/ecti-eec.2019172.215488 ◽

2019 ◽

Vol 17 (2) ◽

pp. 193-203 ◽

Cited By ~ 1

Author(s):

Jie Yi Wong ◽

Phooi Yee Lau

Keyword(s):

Real Time ◽

Low Cost ◽

Economic Losses ◽

Raspberry Pi ◽

Alert System ◽

Driving Experience ◽

The Road ◽

Car Accidents ◽

Passenger Safety ◽

On The Road

Malaysia has been ranked as one of the country in the world with deadliest road. Based on the statistic, there are around 7000 to 8000 people in the country died on the road among the population of 31 million Malaysians every year. In general, Advances Driver Assistance System (ADAS) aims to improve not only the driving experience but also consider the overall passenger safety. In recent years, driver drowsiness has been one of the major causes of road accidents, which can lead to severe physical injuries, deaths and significant economic losses. In this paper, a vison-based real-time driver alert system aimed mainly to monitor the driver’s drowsiness level and distraction level is proposed. This alert system could reduce the fatalities of car accidents by detecting driver’s face, detecting eyes region using facial landmark and calculating the rate of eyes closure in order to monitor the drowsiness level of the driver. Later, the system is embedded into the Raspberry Pi, with a Raspberry Pi camera and a speaker buzzer, and is used to alert the driver in real-time, by providing a beeping sound. Experimental results show that proposed system is practical and low-cost which could (1) embed the drowsiness detection module, and (2) provide alert notification to the driver when the driver is inattentive, using a medium loud beeping sound, in real-time.

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Real-Time Terrain-Following of an Autonomous Quadrotor by Multi-Sensor Fusion and Control

Applied Sciences ◽

10.3390/app11031065 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1065

Author(s):

Yuan Yang ◽

Yongjiang Huang ◽

Haoran Yang ◽

Tingting Zhang ◽

Zixuan Wang ◽

...

Keyword(s):

Real Time ◽

Pid Controller ◽

Low Cost ◽

Satellite System ◽

Height Control ◽

Noise Characteristics ◽

Constant Height ◽

Terrain Following ◽

Global Navigation Satellite ◽

And Control

For the application of the autonomous guidance of a quadrotor from confined undulant ground, terrain-following is the major issue for flying at a low altitude. This study has modified the open-source autopilot based on the integration of a multi-sensor receiver (a Global Navigation Satellite System (GNSS)), a Lidar-lite (a laser-range-finder device), a barometer and a low-cost inertial navigation system (INS)). These automatically control the position, attitude and height (a constant clearance above the ground) to allow terrain-following and avoid obstacles based on multi-sensors that maintain a constant height above flat ground or with obstacles. The INS/Lidar-lite integration is applied for the attitude and the height stabilization, respectively. The height control is made by the combination of an extended Kalman filter (EKF) estimator and a cascade proportional-integral-derivative (PID) controller that is designed appropriately for the noise characteristics of low accuracy sensors. The proposed terrain-following is tested by both simulations and real-world experiments. The results indicate that the quadrotor can continuously navigate and avoid obstacles at a real-time response of reliable height control with the adjustment time of the cascade PID controller improving over 50% than that of the PID controller.

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THE DIRECT GEOREFERENCING APPLICATION AND PERFORMANCE ANALYSIS OF UAV HELICOPTER IN GCP-FREE AREA

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-1-w4-151-2015 ◽

2015 ◽

Vol XL-1/W4 ◽

pp. 151-157 ◽

Cited By ~ 5

Author(s):

C. F. Lo ◽

M. L. Tsai ◽

K. W. Chiang ◽

C. H. Chu ◽

G. J. Tsai ◽

...

Keyword(s):

Real Time ◽

Spatial Information ◽

Disaster Relief ◽

Low Cost ◽

Flight Test ◽

Satellite System ◽

Aerial Images ◽

Positioning Accuracy ◽

Dg Module ◽

Global Navigation Satellite

There are many disasters happened because the weather changes extremely in these years. To facilitate applications such as environment detection or monitoring becomes very important. Therefore, the development of rapid low cost systems for collecting near real-time spatial information is very critical. Rapid spatial information collection has become an emerging trend for remote sensing and mapping applications. This study develops a Direct Georeferencing (DG) based Unmanned Aerial Vehicle (UAV) helicopter photogrammetric platform where an Inertial Navigation System (INS)/Global Navigation Satellite System (GNSS) integrated Positioning and Orientation System (POS) system is implemented to provide the DG capability of the platform. The performance verification indicates that the proposed platform can capture aerial images successfully. A flight test is performed to verify the positioning accuracy in DG mode without using Ground Control Points (GCP). The preliminary results illustrate that horizontal DG positioning accuracies in the x and y axes are around 5 meter with 100 meter flight height. The positioning accuracy in the z axis is less than 10 meter. Such accuracy is good for near real-time disaster relief. The DG ready function of proposed platform guarantees mapping and positioning capability even in GCP free environments, which is very important for rapid urgent response for disaster relief. Generally speaking, the data processing time for the DG module, including POS solution generalization, interpolation, Exterior Orientation Parameters (EOP) generation, and feature point measurements, is less than 1 hour.

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Performance Assessment of Real-Time Multiconstellation GNSS PPP Using a Low-Cost Dual-Frequency GNSS Module

Artificial Satellites ◽

10.2478/arsa-2021-0005 ◽

2021 ◽

Vol 56 (3) ◽

pp. 37-56

Author(s):

Abdelsatar Elmezayen ◽

Ahmed El-Rabbany

Keyword(s):

Real Time ◽

Low Cost ◽

Autonomous Vehicle ◽

Satellite System ◽

Dual Frequency ◽

Positioning Accuracy ◽

Gps Satellites ◽

Solution Convergence ◽

Challenging Environment ◽

Global Navigation Satellite

Abstract The release of low-cost dual-frequency (DF) global navigation satellite system (GNSS) modules provides an opportunity for low-cost precise positioning to support autonomous vehicle applications. The new GNSS modules support the US global positioning system (GPS) L1C/L2C or L5 civilian signals, the Russian GNSS Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS) L1/L2, Europe’s GNSS Galileo E1/E5b, and Chinese GNSS BeiDou B1/B2 signals. The availability of the DF measurements allows for removal of the ionospheric delay, enhancing the obtained positioning accuracy. Unfortunately, however, the L2C signals are only transmitted by modernized GPS satellites. This means that fewer GPS DF measurements are available. This, in turn, might affect the accuracy and the convergence of the GPS-only precise point positioning (PPP) solution. Multi-constellation GNSS PPP has the potential to improve the positioning accuracy and solution convergence due to the high redundancy of GNSS measurements. This paper aims to assess the performance of real-time quad-constellation GNSS PPP using the low-cost u-blox Z9D-F9P module. The assessment is carried out for both open-sky and challenging environment scenarios. Static, simulated-kinematic, and actual field-kinematic trials have been carried out to evaluate real-time PPP performance. Pre-saved real-time precise orbit and clock products from the Centre National d’Etudes Spatiales are used to simulate the real-time scenario. It is shown that the quad-constellation GNSS PPP using the low-cost u-blox Z9D-F9P module achieves decimeter-level positioning accuracy in both the static and simulated-kinematic modes. In addition, the PPP solution convergence is improved compared to the dual- and triple-constellation GNSS PPP counterparts. For the actual kinematic trial, decimeter-level horizontal positioning accuracy is achieved through the GPS + GLONASS + Galileo PPP compared with submeter-level positioning accuracy for the GPS + GLONASS and GPS + Galileo PPP counterparts. Additionally, submeter-level vertical positioning accuracy is achieved through the GPS + GLONASS + Galileo PPP compared with meter-level positioning accuracy for GPS + GLONASS and GPS + Galileo PPP counterparts.

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