GPS – A Vital Component in a Fleet Management System


Srinivas Manda
InfoTech Enterprises Ltd., Plot 11, Madhapur,
Hyderabad 500033
Email: srinivas_manda@infotech.stph.net
Tel.No: +91-040-3100855

Abstract
Monitoring and managing the mobile assets are the core functionalities of any company dealing with the services, delivery or transport vehicles. Technologies help in supporting these functionalities from remote locations and update the managers with the latest positions of their mobile assets. Getting the real time latest position of their running mobile assets is a major requirement for the managers. GPS is one of the rapid growing technologies that provide the accurate geographic positional value of the mobile asset. The output positional value is used to derive various other features required for management of these mobile assets. There are various methods to obtain the positional value and GPS proves to be an ideal solution for calculation. This paper explains the role of GPS in managing the mobile assets and how this is advantageous over the other location calculating mechanisms.

Introduction
In any typical small to medium sized transport industry initial vehicle investment can represent 60% to 70% of the company’s fixed asset base. A significant amount of operational costs per vehicle are also incurred by the industry. Thus in any industry investing on mobile assets it is important to track and manage these assets for various reasons. This is more important in case of the industries investing in transport sector.

In earlier days managers have relied on log sheets, service forms and other paper record keeping systems to keep track of business fleet vehicle operations. To the extent possible, much of this process is automated. Technology now exists to further improve these processes.

Fleet management technology is the technology to measure and expand the areas of safety, reliability, and savings especially for industries that depend upon service, delivery and transport vehicles to accomplish their core business. Fleet Management deals with activities and functions related to maintenance, accountability, and efficient operation of company’s mobile assets.

GPS is one of the major components along with the communication and application software components in a fleet management system. Output of GPS component is a geographic positional value from which primary functionalities for fleet management are derived. An attempt has been made in this paper to bring out the importance of GPS in fleet management system.

GPS in Fleet Management


GPS technology is one of the critical components in emerging fleet management industry. It is combined with the wireless communication, and computer-based application software for the latest in vehicle-based tracking, location, monitoring, diagnostic capability and other related tasks. The specified combination provides a synoptic view of the fleet vehicle activity, instant location and graphic annotation of key events. Figure1 shows the architecture using GPS in the Fleet Management System.

Figure 1: Fleet Management System Architecture
The Fleet Management technology is a congruence of the following technologies

1. GPS technology.
2. Technology to communicate the output from GPS component.
3. Technology to analyse and view output from GPS component.

What is GPS?
GPS is a location-based technology relying on a network of 24 active satellites orbiting the earth at an altitude of 20,000 km. These satellites constantly transmit radio signals to earth stations and GPS receivers. At any instant of time there will be at-least three satellites available anywhere under the sky. A configured GPS receiver can receive the signals from all available satellites in sky and can decide the position of itself in the form of latitude and longitude values.

To calculate a positional value, a receiver needs to acquire information from at least three satellites. The position is calculated based on triangulation method. The greater the number of satellites within line of sight ranges of the receiver, the greater the accuracy of the location data. Using the permutations of the same data, GPS can also calculate the vehicles speed and direction.

Why GPS?
The core functionality in any Fleet Management system is calculation of the positional value of the vehicle. Single positional value or a set of positional values can be analyzed for various fleet management related tasks. Technology used for obtaining the calculated value and the accuracy of the calculated value is of prime importance. Most of the position calculation technologies use the method of triangulation for calculation.

Position calculation technologies mostly use an existing network for the method of triangulation. Triangulation requires the measurement of distance from a minimum of three pre-defined points to calculate the fourth distance and its location. Depending upon the method of calculating the distances from the pre-defined points, the position calculation can be of different types as described below

1. Ground based network technology, using the earth based ground towers from cell sites serving the mobile phones. In order to calculate the positional value it can use any of the following techniques:
   1. Cell-id: This technology employs a cellular network's inherent capability to recognize which sector of a cell site a phone is communicating with. It then enhances the data to determine which area of the cell sector the caller is in.
   2. TDOA: Time Difference of Arrival (TDOA), the mobile device is the source of the signal. Equipment at the wireless operator's base stations then detects the signal and calculates the location. Since mobile devices do not need to be modified to work, this technology can operate with all existing handsets and devices.
   3. AOA: In Angle of arrival (AOA) method, the angle of arrival of a signal between the mobile phone and the cellular antenna is analysed. AOA in conjunction with network-based position determination equipment is used to position the mobile device.
   4. E-OTD: Enhanced- observed Time Difference (E-OTD) operates on the same principle as GPS except that, instead of originating from satellites, signals are sent from cellular base stations and then picked up by special handsets. In E-OTD, the location is calculated in the phone.
2. Use of smart devices is another technique that can be used for position calculation. Smart devices are located at fixed places and once the vehicle comes with its range required parameters are recorded which either get stored for later retrieval or get transmitted to base station in real time.
3. Based on the satellite technology like GPS. By itself, GPS can be the most accurate (when satellites are acquired/available). GPS technology calculates the positional values depending on the distance calculations from the available constellation of 24 satellites.
   
   The ground-based network for faster and accurate calculation of the positional value often enhances this technology. This method of calculation is referred to as Assisted GPS (A-GPS). This refers to a system that makes use of additional network equipment that is deployed to help acquire the mobile device (much faster than non-assisted GPS) and provide positioning when the A-GPS system is unsuccessful in acquiring any/enough satellites.

Ground based network technology has a drawback on accuracy of the calculated positional value. The accuracy of the location data is greatly dependent on the cell size (the smaller the better) or the number of location measurement units. Highly dense areas like congested urban areas can cause high dilution of accuracy. Availability of network connectivity and continuity may become major hindrance in position calculation. Smart device facility does not provide a flexible technique as these are at fixed locations and vehicles routes may differ from these locations.

Among the above-specified technologies, GPS technology proves to be an ideal solution for position calculation. Availability of the network is continuous. At any given instant of time the GPS receiver is in contact with at least 3 satellites, therefore it never fails to detect the location of a vehicle. The accuracy of the calculated values is 1 to 50 mts with 95% confidence level. There might be some dilution in the accuracy of the calculated values in the areas of high population density covered with tall buildings. Following table shows the comparison between accuracies (mts) in different technologies.

Technology	Areas of high signal blockage and multipath	Areas of medium signal blockage and multipath	Areas on low signal blockage and multipath
Cell-id	250	>500	>1000
TDOA	50	50	80
E-OTD	150	100	100
GPS	50-25	25-10	<10

Following are some of the features that can be derived from the calculated positional value:

• Vehicle tracking
• Nearest vehicle service centers
• Vehicle speed calculation
• Onboard equipment usage
• Vehicle diagnostics
• Tracking routes including the stoppages
• “Geo-fencing” verification to ensure vehicles stays within a defined geographical area and also alerts vehicle entering a restricted zone.

Communication of GPS Output
Outputs from GPS include the positional values, speed and direction. These calculations made by GPS are to be transmitted to the fleet control center through wireless communication mechanism. These calculations can be communicated through any of the following:

• Radio Frequency (UHF/VHF)
  • Pros
    Cheaper technology
    Widely available
    
  • Cons
    Not continuous
    Shadow regions
    Possible interruptions
• Wireless communication technologies like CDMA, GPRS, GSM etc.
  • Pros
    Relatively cheaper technology
    Widely available within urban areas
    No interruptions due to obstructions
    
  • Cons
    Not continuous
    Dependency on the service provider
• MSS Satellite technology
  • Pros
    Continuous availability
  • Cons
    Expensive
    Not suitable in urban environments as the location calculation operates on line of sight visibility of satellites

Fleet Manager: For Analysing and Viewing GPS Output
GPS outputs the positional values and other position related parameters like speed and direction, which are spatially related. Some of these calculation can be directly viewed though the developed application. Various other features can be derived from these calculations by way of analysis. It is required to have a fleet management application with a GIS component in order to analyse and visualize the GPS calculations. Various features that can be derived for a fleet management application include several functionalities depending upon the service offered by the concerned company. Depending upon the usability, the features can be divided into primary and secondary. Following is the list of some of the primary and secondary functionalities included in the fleet management application:

Primary

• Real Time Vehicle Tracking on map.
• Two way Communication to vehicles.
• Stoppage analysis and reports.
• Multiple maps in multiple windows.
• Instant glance on vehicle data (id, registration type, etc.,).
• History and analysis with a PLAY BACK facility.
• Display of nearest landmark.
• Speed control
• Geo-fencing/Zone restriction

Secondary

• Grouping of vehicles with different colors.
• Optimal path calculations, distance calculations.
• Maintenance of driver records
• Maintenance of Vehicle records
• Traffic Information integration
• Route guidance
• Vehicle diagnostics through integration of sensors

In addition to the above, applications can include some additional features depending upon the requirement.

Figure2 shows the tracking functionality in a fleet management system for a particular vehicle.

Figure 2: Vehicle tracking in Fleet Management
Conclusion
From the above discussion it is evident that GPS component plays a major role through calculation of positional value, speed and direction from which various other features for fleet management can be derived. GPS proves as an ideal solution for calculation of positional values compared to the other technologies available for doing so. GPS provides an accurate and reliable positional value with a continuous connectivity to the satellites.

Acknowledgements
I thank Mr. B.V.R. Mohan Reddy, Managing Director, InfoTech Enterprises Limited and Mr. Rajeev Lal, Chief Operating Officer who have been a constant source of dynamism and inspiration to all of us. I am also thankful to Mr.U.Srinivas, Dr.V.N.Sharma and all other associates for their support in preparation of this paper.

References

• Mehta. P, Aggrawal. P and Shukla. R GPS based fleet management system: Different alternatives MapIndia 2002
• White Paper on GPS Fleet Management from FLEETBOSS.com
• Jason. A. The right technology is vital for location-based applications wireless.iop.org/article/news