Autonomous Global Positioning System Research Articles

Intelligent Distribution Framework and Algorithms for Connected Logistics Vehicles

This study presents an intelligent distribution framework based on edge computing and proposes navigation and obstacle avoidance algorithms for connected logistics vehicles (CLVs) on the basis of Trimble BD982 positioning sensor and tentacle algorithm (TA). An edge computing framework for the distribution of CLVs is established, and the functions of three layers (cloud server, edge equipment, and terminal) are described in detail. The basic functions, hardware, and software systems of the CLV are designed and presented. Focusing on autonomous driving, a Global Positioning System (GPS) navigation algorithm and an obstacle avoidance control strategy on the layer of edge equipment are developed on the basis of the TA. Autonomous GPS navigation is realized by combining the entire road network with the local road network to avoid obstacles. The TA is improved to help the CLV for avoiding obstacles. Experiments show that the hardware system and designed algorithms of the CLV are effective. The tracking error on the straight-line track is within 3 cm, the change rate of longitudinal velocity is within 0.3 g/s, the change rate of tire side deflection angle is less than 1°/s, and the calculation time is shortened by 25% when the calculation time is 30 ms. These results indicate that the vehicle has good stability and performance during obstacle avoidance in real time, and the proposed algorithms are superior to traditional algorithms. The CLV can realize autonomous GPS navigation, with high navigation accuracy, reliable obstacle avoidance performance, and stable vehicle handling.

ASSESSMENT OF GPS/GLONASS POINT POSITIONING IN BRAZILIAN REGIONS WITH DISTINCT IONOSPHERIC BEHAVIOR

Nowadays GPS (Global Positioning System) and GLONASS (GLObal NAvigation Satellite System) are the main systems of GNSS (Global Navigation Satellite Systems), also composed by Galileo and BeiDou. After a long period of degradation, GLONASS was modernized, and its constellation was reestablished in 2011. Considering this new scenario, with GPS and GLONASS full constellations, the interest in the combined use of both systems was renewed. Besides the constellations used, other factors are related to the positioning quality, for instance the ionospheric influence. Several studies have been performed aiming to assess GPS positioning quality as well as the ionospheric influence on it, but concerning GLONASS, there are still several possibilities of investigation. In this context, this research aimed to assess the GPS/GLONASS data point positioning performance considering Brazilian regions with different ionospheric behavior during periods of low and high ionospheric activity. Spatial and time ionospheric influence in the positioning performance were observed. Considering all configurations tested with 30-minute data, the use of GPS/GLONASS data provided better results in 97.35% of the cases when compared to autonomous GPS, the mean improvement was about 60 cm, which corresponds to 30%.

Development of Real-Time PPP-Based GPS/INS Integration System Using IGS Real-Time Service for Hydrographic Surveys

AbstractThe multibeam echosounding technique is used to provide seafloor mapping at a relatively high-quality level and requires an accurate positioning and orientation system. Integration of a global positioning system (GPS) and an inertial navigation system (INS) is widely used for positioning and orientation control and is performed by using an inertial unit integrated with a real-time kinematic (RTK) GPS solution with two GPS receivers to provide the required accuracy. However, the RTK-based GPS/INS system is presently limited to a distance of approximately 10 km and cannot be used for offshore hydrographic surveys. Recently, precise-point positioning (PPP) technology has shown promise toward the development of an autonomous GPS solution for positioning applications in which only one GPS receiver is used. This paper investigates a real-time PPP-based GPS/INS integrated system position and orientation solution using the international GPS service (IGS) real-time service (RTS) for hydrographic surveys. T...

Spacecraft Autonomous GPS Navigation based on Polytopic Linear Differential Inclusion

Aiming at improving the poor real-time performance of existing nonlinear filtering algorithms applied to spacecraft autonomous navigation based on Global Positioning System (GPS) measurements and simplifying the algorithm design of navigation algorithms, a spacecraft autonomous navigation algorithm based on polytopic linear differential inclusion is proposed in this paper. Firstly, it is demonstrated that the nonlinear estimation error system of spacecraft autonomous navigation can be modelled as a polytopic linear differential inclusion system model according to the idea of global linearization. Thus, the filtering of a nonlinear system simplified to a filtering of a polytopic linear system with coefficients. Secondly, Tensor-Product (TP) model transformation is applied to determine the polytopic linear differential inclusion system model. The model error introduced by global linearization is reduced and the compromise between computational complexity and modelling accuracy is realised. Finally, a spacecraft autonomous navigation algorithm based on polytopic linear differential inclusion is designed by combining multi-model Kalman filtering with data fusion. Compared with an Extended Kalman Filter (EKF), the proposed algorithm is simpler and easier to implement since it need not update the Jacobian matrices online. Simulation results demonstrate the same estimation accuracy of the proposed algorithm to that of EKF.

First Brazilian Real Time Network DGPS through the Internet: Development, Application and Availability Analyses

First Brazilian Real Time Network DGPS through the Internet: Development, Application and Availability AnalysesThe Global Positioning System (GPS) is widely used by the civil community. Differential GPS (DGPS) was developed to provide better accuracy than autonomous GPS. The DGPS concept is based on the high correlation of errors due to atmospheric effects, satellite clocks and orbits. However, as the baseline grows, its efficiency decreases because the error correlation is reduced. This limitation can be handled by using a reference station network and applying the network DGPS concept (called NDGPS). In this paper, the goal is to present aspects related to the development and application of NDGPS in real time at the São Paulo state network in Brazil. The NDGPS corrections were computed from data received via the Internet using NTRIP (Networked Transport of RTCM via Internet Protocol). Our implementation was based on BNC (BKG Ntrip Client) software. NDGPS provided RMS improvements of up to 59% in horizontal components and 31% in vertical components when compared to DGPS. The availability of the system, the first of this nature in Brazil, was also analyzed within the context of the SP State GNSS Network, located in the southeastern region of Brazil. The results also serve as an indication of the quality of local internet infrastructure for using in geodetic positioning.

Using an optical mouse sensor to track geophysical field measurements

To position arbitrary outdoor measurements, the most common methods are the use of global positioning system (GPS) technology or distance tracking from reference locations. The system to be introduced here consists of a combination of an optical distance tracking system and a civil, autonomous GPS receiver. Through the application of a recursive filter, both components support and correct each other mutually. The system is intended as an autonomous, real-time and low-cost alternative to expensive differential GPS solutions in geophysical field surveying. The combination approach features a very good relative and decent absolute positioning precision. First measurements using the two-coil geo-electromagnetics instrument Geonics EM31 in combination with the developed positioning system show promising results.

GPS/INS navigation precision and its effect on airborne radio occultation retrieval accuracy

An airborne radio occultation (RO) system has been developed to retrieve atmospheric profiles of refractivity, moisture, and temperature. The long-term objective of such a system is deployment on commercial aircraft to increase the quantity of moisture observations in flight corridors in order to improve weather forecast accuracy. However, there are several factors important to operational feasibility that have an impact on the accuracy of the airborne RO results. We investigate the effects of different types of navigation system noise on the precision of the retrieved atmospheric profiles using recordings from the GNSS Instrument System for Multistatic and Occultation Sensing (GISMOS) test flights, which used an Applanix POS/AV 510 Global Positioning System (GPS)/Inertial Navigation System (INS). The data were processed using a carrier phase differential GPS technique, and then the GPS position and inertial measurement unit data were combined in a loosely coupled integrated inertial navigation solution. This study quantifies the velocity precision as a function of distance from GPS reference network sites, the velocity precision with or without an inertial measurement unit, the impact of the quality of the inertial measurement unit, and the compromise in precision resulting from the use of real-time autonomous GPS positioning. We find that using reference stations with baseline lengths of up to 760 km from the survey area has a negligible impact on the retrieved refractivity precision. We also find that only a small bias (less than 0.5% in refractivity) results from the use of an autonomous GPS solution rather than a post-processed differential solution when used in an integrated GPS/INS system. This greatly expands the potential range of an operational airborne radio occultation system, particularly over the oceans, where observations are sparse.

Effects of polyline simplification of dynamic GPS data under forest canopy on area and perimeter estimations

The objectives of this study were to determine Global Positioning System (GPS) positional errors while moving under the forest canopy and to clarify the effects of polyline simplification on area and perimeter estimations. We used the Pathfinder Pro XR and GPSMAP 76S, which are categorized as “high-end mapping” and “general navigation” GPS receivers, respectively. The field tests were conducted in both natural and plantation forests. The results showed that the Pathfinder Pro XR, which has better multipath rejection technology, worked well, especially in the plantation forest under unfavorable conditions of higher stand density. We used analysis of variance to clarify the effects of the receiver type, positioning mode, stand type, and polyline simplification method on area and perimeter estimations. The receiver type and positioning mode were found to be significant factors that affected area estimation. The Pathfinder Pro XR estimated the area more accurately than the GPSMAP 76S, and differential GPS estimated the area more accurately than autonomous GPS. With respect to the perimeter, the receiver type, positioning mode, and polyline simplification method were found to be significant factors. The results showed that perimeter estimation was improved by using the velocity filter, and further improved by using the velocity filter and Douglas-Peucker algorithm, especially when the Pathfinder Pro XR was used. The GPSMAP 76S estimated the perimeter accurately without any filtering because its default speed filter worked well, even though the GPSMAP 76S is a general navigation GPS receiver.

Optimal statistical fault detection with nuisance parameters

Fault detection is addressed within a statistical framework. The goal of this paper is to propose an optimal statistical tool to detect a fault in a linear stochastic (dynamical) system with uncertainties (nuisance parameters or nuisance faults). It is supposed that the nuisance parameters are unknown but non-random; practically, this means that the nuisance can be intentionally chosen to maximize its negative impact on the monitored system (for instance, to mask a fault). Examples of ground station based and receiver autonomous Global Positioning System (GPS) integrity monitoring illustrate the proposed method.

Development and evaluation of a support system for forest education

Field education programs have been conducted throughout the world because learning through experience is an important process in environmental and forest education. We developed a support system for forest education that consists mainly of a Global Positioning System (GPS) and personal digital assistant (PDA). Moreover, field experiments were conducted to evaluate educational efficacy as well as usability of the developed system. Through a post-questionnaire the developed system was highly evaluated in terms of educational efficacy and enjoyment. On the other hand, the questionnaire revealed the need for technical improvements. For example, the drawing function, which involves the use of a stylus pen, was the most poorly evaluated because a drawing could not be partially erased as with an eraser and representation was not sufficiently accurate. In addition, positions where information on nature appeared were sometimes inaccurate due to positional errors caused by using the autonomous GPS. Some participants answered that walking with the developed system was also troublesome due to its shape and size. In fact, they did not feel comfortable about the cables connecting the GPS to the PDA and GPS to its antenna. Although there were some problems with the system, we believe that the field education program was successful because 95% of the participants answered that they would join a similar program again.

Quasi-continuous global positioning system measurements of glacial isostatic deformation in the Northern Transantarctic Mountains

Global positioning system (GPS) measurements have been collected quasi-continuously between November 1996 and January 2001 at two autonomous GPS stations in the Northern Transantarctic Mountains. High-quality data from the two sites at Mt. Coates in the Dry Valleys and Mt. Cocks in the Royal Society Range have resolved significant horizontal motions. The vertical rate at Mt. Coates indicates an uplift of 4.5±2.3 mm/year, most likely due to glacial isostatic motion. Uplift at Mt. Coates deviates significantly from uplift predictions based on deglaciation models ICE-3G and ICE-4G, but is consistent with a model (D91-1.5) in which deglaciation persists up to the late Holocene.

Comparing the precision and accuracy of GPS positioning in forested areas

The objective of this study is to clarify the performance of the Global Positioning System (GPS) in forested areas after selective availability (SA) was turned off. In this study, we conducted a field test on horizontal and vertical positional errors of GPS positioning at different points in forested areas. The precision and accuracy of GPS positioning at different points were then calculated and compared. Furthermore, the effect of differential GPS (DGPS) on precision and accuracy was analyzed using analysis of variance (ANOVA), and the necessity for DGPS after SA was turned off was discussed. As a result, the largest horizontal precision errors were found to be in the plantation forest, followed by the natural forest and forest road. On the other hand, precision errors were smallest at the landing, around which there were no obstacles. Horizontal accuracy errors were greatly improved by using the DGPS. Large vertical precision errors were produced in the plantation forest, on the forest road, and in the natural forest, while those at the landing were much smaller. Vertical accuracy errors were also relatively small at the landing. In conclusion, tree canopies greatly affected precision errors, and the DGPS improved not horizontal precision but horizontal accuracy. The autonomous GPS is sufficiently useful for purposes in which horizontal positional errors of a maximum of 10m are allowable. However, the DGPS should be used for surveying and mapping, for which higher accuracy is necessary.

GPS and GIS: Enhanced Accuracy in Map Matching through Effective Filtering of Autonomous GPS Points

The development of the Global Positioning System (GPS), along with ever more powerful geographic information systems (GIS), has spawned the development of public safety applications. One of the most noteworthy of these applications is the Mayday system in which a motorist can call for roadside assistance at any time, day or night, without knowing his location, so that a service center can send assistance to the site of the call. Some of today's Mayday systems provide national coverage which, while impressive in scope, can cause problems in assuring the reliability required to enlist the loyalty of customers and the cooperation of local emergency personnel. Customers whose calls for assistance are not answered promptly, or frequent calls that result in long searches by emergency personnel taking them away from their posts and endangering others who need them, are potential pitfalls of Mayday systems. This paper looks at the effects of filtering autonomous GPS points to enhance the reliability of positions when matched to maps in GIS databases.