scholarly journals Reducing time to navigation solution in warm start mode

2020 ◽  
pp. 22-26
Author(s):  
S. A. Semenov ◽  
A. E. Fridman
Keyword(s):  
Waiting Time ◽  
Time Variable ◽  
Navigation Systems ◽  
Additional Time ◽  
Navigation Problem ◽  
Navigation Solution ◽  
Warm Start ◽  
Hot Start ◽  
The Cost ◽  
Initial Synchronization

The article is devoted to the problem of reducing the time between switching on the navigation receiver and getting a navigation solution in the case when the available accuracy of the initial synchronization of the receiver’s time scale is insufficient for the implementation of a hot start scenario. An algorithm is proposed and mathematically justified that allows achieving the average waiting time for the first solution, typical for a hot start, when the conditions for a warm start are met. The novelty of the presented approach consists in the introduction of an additional time variable into the estimated state vector of the system, which allows solving the navigation problem even if it is impossible to calculate the pseudo-dalities of navigation satellites using classical methods. The use of the proposed algorithm opens up wide prospects for simplifying and reducing the cost of navigation systems, which is especially important in a number of special applications. The results of testing the described method on real measurements and in mass-produced products are presented.

Analysis of Influence of Ephemeris-Time Information on Accuracy of Solving a Navigation Problem by Signals of GLONASS System

2020 ◽  
Vol 25 (5) ◽  
pp. 465-474
Author(s):  
V.O. Zhilinskiy ◽  
◽  
D.S. Pecheritsa ◽  
L.G. Gagarina ◽  
◽  
...  
Keyword(s):  
High Precision ◽  
Satellite Navigation ◽  
Satellite System ◽  
Navigation Systems ◽  
Navigation Problem ◽  
Satellite Navigation System ◽  
Study Results ◽  
Accuracy Of Measurements ◽  
Huge Impact ◽  
Time Information

The Global Navigation Satellite System has a huge impact on both the public and private sectors, including the social-economic development, it has many applications and is an integral part of many domains. The application of the satellite navigation systems remains the most relevant in the field of transport, including land, air and maritime transport. The GLONASS system consists of three segments and the operation of the entire system depends on functioning of each component, but primarily, the accuracy of measurements depends on the basis forming of the control segment and management, responsible for forming ephemeris-time information. In the work, the influence of ephemeris-time information on the accuracy of solving the navigation problem by the signals of the GLONASS satellite navigation system has been analyzed. The influence of both ephemeris information and the frequency information, and of the time corrections has been individually studied. The accuracy of the ephemeris-time information is especially important when solving the navigation problem by highly precise positioning method. For the analysis the following scenarios of the navigation problem solving have been formed: using high-precision and broadcast ephemeris-time information, a combination of broadcast (high-precision) ephemeris-time information, and high-precision (broadcast) satellite clock offsets and two scenarios with simulation of the calculation of the relative correction to the radio signal carrier frequency. Based on the study results it has been concluded that the contribution of the frequency-time corrections to the error of location determination is of the greatest importance and a huge impact on the error location, while the errors of the ephemeris information are insignificant

scholarly journals S-PDR: SBAUPT-Based Pedestrian Dead Reckoning Algorithm for Free-Moving Handheld Devices

Geomatics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 148-176
Author(s):  
Maan Khedr ◽  
Naser El-Sheimy
Keyword(s):  
Smart Cities ◽  
Dead Reckoning ◽  
Human Motion ◽  
Indoor Navigation ◽  
Location Based Services ◽  
Navigation Systems ◽  
Short Term ◽  
Navigation Solution ◽  
Correction Technique ◽  
Pedestrian Dead Reckoning

Mobile location-based services (MLBS) are attracting attention for their potential public and personal use for a variety of applications such as location-based advertisement, smart shopping, smart cities, health applications, emergency response, and even gaming. Many of these applications rely on Inertial Navigation Systems (INS) due to the degraded GNSS services indoors. INS-based MLBS using smartphones is hindered by the quality of the MEMS sensors provided in smartphones which suffer from high noise and errors resulting in high drift in the navigation solution rapidly. Pedestrian dead reckoning (PDR) is an INS-based navigation technique that exploits human motion to reduce navigation solution errors, but the errors cannot be eliminated without aid from other techniques. The purpose of this study is to enhance and extend the short-term reliability of PDR systems for smartphones as a standalone system through an enhanced step detection algorithm, a periodic attitude correction technique, and a novel PCA-based motion direction estimation technique. Testing shows that the developed system (S-PDR) provides a reliable short-term navigation solution with a final positioning error that is up to 6 m after 3 min runtime. These results were compared to a PDR solution using an Xsens IMU which is known to be a high grade MEMS IMU and was found to be worse than S-PDR. The findings show that S-PDR can be used to aid GNSS in challenging environments and can be a viable option for short-term indoor navigation until aiding is provided by alternative means. Furthermore, the extended reliable solution of S-PDR can help reduce the operational complexity of aiding navigation systems such as RF-based indoor navigation and magnetic map matching as it reduces the frequency by which these aiding techniques are required and applied.

scholarly journals Development of a Priority based System for Emergency Vehicles to Reduce Accidents in VANETs

2020 ◽  
Vol 9 (2) ◽  
pp. 483-486
Keyword(s):  
Waiting Time ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Human Life ◽  
Traffic Signals ◽  
Emergency Vehicles ◽  
Movement System ◽  
Hoc Networks ◽  
The Cost ◽  
Vehicle Movement

Due to tremendous increase of vehicles in number leads to excessive congestion of vehicles at intersection of roads. It causing inconvenience to emergency vehicles like Ambulance and Fire brigade etc, ultimately which is the cost of human life To avoid this, Emergency Vehicles will have to give high priority to overcome from the congestion. Vehicular Ad-Hoc Networks (VANETs) is a network which is used to create a temporary communication among the vehicles. In this paper, priority based vehicle movement system is proposed to give high priority to emergency vehicles and establishing communication among the vehicles through VANET. Due to this high priority, there is no necessity to wait for the emergency vehicles at the traffic signals to get the green signal while communicating with traffic controller. In this paper, SUMO simulator is used for experimental analysis. The result indicates that the proposed methodology reduces the waiting time when compared to the existing system.

Combination Service for Time-variable Gravity Fields (COST-G): operational GRACE-FO combination and validation of Chinese GRACE time-series

2021 ◽  
Author(s):  
Ulrich Meyer ◽  
Martin Lasser ◽  
Adrian Jäggi ◽  
Christoph Dahle ◽  
Frank Flechtner ◽  
...  
Keyword(s):  
Time Series ◽  
Quality Assessment ◽  
International Association ◽  
Time Variable ◽  
Operational Mode ◽  
Time Variable Gravity ◽  
Gravity Fields ◽  
Variable Gravity ◽  
Processed Products ◽  
The Cost

<p>The Combination Service for Time-variable Gravity Fields (COST-G) of the International Association of Geodesy (IAG) provides combined monthly gravity fields of its associated and partner Analysis Centers (ACs). In November 2020, the combination of monthly GRACE-FO gravity fields started its operational mode, providing consolidated L2 (spherical harmonics) and L3 (gridded and post- processed) products with a latency of currently 3 months. We present an overview and quality assessment of the available products.</p><p>COST-G aims at the extension of its service to include further GRACE and GRACE-FO analysis centers. In January 2020 a collaboration with representatives of five Chinese ACs was initiated, who provided GRACE time-series according to the COST-G requirements. We present the results of a test combination with the Chinese AC models, including comparison and quality assessment of all contributing time-series and validation of the combined gravity fields.</p>

Effects and Benefits of Space Exploration

2012 ◽  
Vol 2 (1) ◽  
pp. 49-62
Author(s):  
Norma B. Crosby
Keyword(s):  
Space Exploration ◽  
Cost Benefit ◽  
Harsh Environments ◽  
Navigation Systems ◽  
Space Technology ◽  
The Moon ◽  
Modern Life ◽  
Human Needs ◽  
Transfer Of Technology ◽  
The Cost

It has been more than half a century since humans first ventured into space. While competing in being the first to land on the Moon, they learned to utilize space for human needs on Earth (e.g., telecommunications, navigation systems). Many space technologies were later applied to basic needs on Earth. Space research and development led to the “transfer of technology” in non-space sectors and became better known as “spin-offs.” They have improved global modern life in many ways. This paper discusses the cost-benefit of space technology spin-offs, as well as the relationships between various space agencies, spin-offs, and commercial enterprises. Other benefits that have come out of space exploration such as psychological, political and environmental effects are also reviewed, as well as the potential future benefits of going to space. Technologies developed for harsh environments on Earth and for those in space benefit all and collaborating both ways is the future.

Note: The Value and Cost of the Customer’s Waiting Time

2020 ◽  
Author(s):  
Rachel R. Chen ◽  
Subodha Kumar ◽  
Jaya Singhal ◽  
Kalyan Singhal
Keyword(s):  
Waiting Time ◽  
Queue Length ◽  
Relative Cost ◽  
Queuing Models ◽  
Underlying Causes ◽  
Two Measures ◽  
Expected Waiting Time ◽  
The Cost ◽  
Shed Light ◽  
Key Parameter

The (relative) cost of the customer’s waiting time has long been used as a key parameter in queuing models, but it can be difficult to estimate. A recent study introduced a new queue characteristic, the value of the customer’s waiting time, which measures how an increase in the total customer waiting time reduces the servers’ idle time. This paper connects and contrasts these two fundamental concepts in the queuing literature. In particular, we show that the value can be equal to the cost of waiting when the queue is operated at optimal. In this case, we can use the observed queue length to compute the value of waiting, which helps infer the cost of waiting. Nevertheless, these two measures have very different economic interpretations, and in general, they are not equal. For nonoptimal queues, comparing the value with the cost helps shed light on the underlying causes of the customer’s waiting. Although it is tempting to conclude that customers in a queue with a lower value of waiting expect to wait longer, we find that the value of waiting in general does not have a monotonic relationship with the expected waiting time, nor with the expected queue length.

The Application of Inertia Navigation Systems to Civil Air Transport

1963 ◽  
Vol 16 (3) ◽  
pp. 265-266
Keyword(s):  
Inertial Sensors ◽  
Instantaneous Velocity ◽  
Air Transport ◽  
Lower Grade ◽  
Navigation Systems ◽  
Military Aircraft ◽  
Considerable Advantage ◽  
Civil Aircraft ◽  
Navigational Aid ◽  
The Cost

Navigation by the use of inertial information is now an accepted technique for military aircraft and for missiles. In civil aircraft the application of inertial techniques are, as yet, limited to defining the vertical and providing a memory of azimuth direction; that is, as aids to flight rather than a primary or even sole navigational aid. Although the principles applied—the inertial properties of matter and the laws of gravitation—are the same, the accuracy of the inertial sensors differs by some three orders of magnitude, and the cost by some two orders, between these two extremes.Mr. A. Stratton of the Royal Aircraft Establishment first of all presents in perspective the range of application of inertial techniques that are available for civil use and suggests how the information obtained by inertial means can be related to that from other airborne sources. He shows that even if the expense of an accurate inertial platform of ‘navigational’ quality should not be justified, considerable advantage over existing sources obtains in terms of accurate attitude reference, and instantaneous velocity and acceleration, by the use of a lower-grade platform in conjunction with other navigation aids.

scholarly journals Specialized Algorithm for Navigation of a Micro Hopping Air Vehicle Using Only Inertial Sensors

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Edward Scheuermann ◽  
Mark Costello
Keyword(s):  
Data Stream ◽  
Inertial Sensors ◽  
Micro Air Vehicles ◽  
Positional Information ◽  
Estimation Accuracy ◽  
Measurement Unit ◽  
Navigation Systems ◽  
Navigation Solution ◽  
Air Vehicle ◽  
Vehicle Position

The need for accurate and reliable navigation techniques for micro air vehicles plays an important part in enabling autonomous operation. Traditional navigation systems typically rely on periodic global positioning system updates and provide little benefit when operating indoors or in other similarly shielded environments. Moreover, direct integration of the onboard inertial measurement unit data stream often results in substantial drift errors yielding virtually unusable positional information. This paper presents a new strategy for obtaining an accurate navigation solution for the special case of a micro hopping air vehicle, beginning from some known location and heading, using only one triaxial accelerometer and one triaxial gyroscope. Utilizing the unique dynamics of the hopping vehicle, a piece-wise navigation solution is constructed by selectively integrating the inertial data stream for only those short periods of time while the vehicle is airborne. Interhop data post processing and sensor bias recalibration are also used to further improve estimation accuracy. To assess the performance of the proposed algorithm, a series of tests were conducted in which the estimated vehicle position following a sequence of 10 consecutive hops was compared with measurements from an optical motion-capture system. On average, the final estimated vehicle position was within 0.70 m or just over 6% from its actual location based on a total traveled distance of approximately 11 m.

An Intelligent Navigation Solution for Land Mobile Location-Based Services

2002 ◽  
Vol 55 (2) ◽  
pp. 225-240 ◽  
Author(s):  
Stephen Scott-Young ◽  
Allison Kealy
Keyword(s):  
Firm Growth ◽  
Spatial Information ◽  
Inertial Sensors ◽  
Low Cost ◽  
Dead Reckoning ◽  
Location Based Services ◽  
Geographical Information ◽  
Navigation Systems ◽  
Navigation Solution ◽  
Lower Accuracy

The increasing availability of small, low-cost GPS receivers has established a firm growth in the production of Location-Based Services (LBS). LBS, such as in-car navigation systems, are not necessarily reliant on high accuracy but a continuous positioning service. When available, the accuracy provided by the standard positioning service (SPS) of 30 metres, 95% of the time is often acceptable. The reality is, however, that GPS does not work in all situations, and it is therefore common to integrate GPS with additional sensors. The use of low-cost inertial sensors alone during GPS signal outage is severely restricted due to the accumulation of errors that is inherent with such dead reckoning (DR) systems. Through the integration of spatial information with real-time positioning sensors, intelligence can be added to the land mobile navigation solution. The information contained within a Geographical Information System (GIS) provides additional observations that can be used to improve the navigation result. With this approach, the solution is not dependent on the performance capabilities of the navigation sensors alone. This enables the use of lower accuracy navigation devices, allowing low-cost systems to provide a sustained, viable navigation solution despite long-term GPS outages. Practical results are presented comparing solutions obtained from a hand-held GPS receiver to a gyroscope and odometer.

scholarly journals Data analysis of ambient intelligence in a healthcare simulation system: a pilot study in high-end health screening process improvement

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ming-Shu Chen ◽  
Kun-Chih Wu ◽  
Yu-Ling Tsai ◽  
Bernard C. Jiang
Keyword(s):  
Waiting Time ◽  
Tertiary Hospital ◽  
Health Screening ◽  
Screening Process ◽  
Arrival Times ◽  
System A ◽  
The Cost ◽  
Bottleneck Resources ◽  
First In First Out ◽  
Northern Taiwan

Abstract Background This study aimed to reduce the total waiting time for high-end health screening processes. Method The subjects of this study were recruited from a health screening center in a tertiary hospital in northern Taiwan from September 2016 to February 2017, where a total of 2342 high-end customers participated. Three policies were adopted for the simulation. Results The first policy presented a predetermined proportion of customer types, in which the total waiting time was increased from 72.29 to 83.04 mins. The second policy was based on increased bottleneck resources, which provided significant improvement, decreasing the total waiting time from 72.29 to 28.39 mins. However, this policy also dramatically increased the cost while lowering the utilization of this health screening center. The third policy was adjusting customer arrival times, which significantly reduced the waiting time—with the total waiting time reduced from 72.29 to 55.02 mins. Although the waiting time of this policy was slightly longer than that of the second policy, the additional cost was much lower. Conclusions Scheduled arrival intervals could help reduce customer waiting time in the health screening department based on the “first in, first out” rule. The simulation model of this study could be utilized, and the parameters could be modified to comply with different health screening centers to improve processes and service quality.

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