Accuracy of location data is of prime importance along with ease of use and availability of the technology. Keeping this in view GPS (Global Positioning System) has emerged as the key technology used in location finding for Fleet Management.
GPS is a satellite-based navigation system developed and operated by the U.S. Department of Defense (DOD). The system is three-dimensional, free of use, global and able to operate 24 hours a day under all weather conditions. GPS offers high accuracy level, especially when the Selective Availability function, which is set up by US military to limit the outside users of GPS, is turned off.
Since the satellites are positioned at a high altitude, a GPS receiver is in contact with at least 5 GPS satellites at any time. Therefore GPS receiver never fails to detect the location of a vehicle. By using TDOA, the distance between the calculated and actual locations (the amount of deviation or location error) is 1 to 10 meters with 95% confidence level. This precision has been achieved and made available to public by an US Government Regulation dated May 1st 2000.
The inherent advantages of GPS make it a suitable choice for location finding technique in a Fleet Management System.
GPS based Fleet Management Systems and their solutions are dependent on the various requirements determining size, accuracy, economic constraints and the like affecting, in turn, efficiency, productivity and profitability.
GPS based Fleet Management Systems could be divided in to three major types:
Screen Shot depicting Real Time Vehicle Tracking
Active Fleet Management Systems
- Active Fleet Management Systems
- Passive Fleet Management Systems
- Hybrid Fleet Management Systems
These specialise in Automatic Vehicle Location (AVL). This system is based on tracking real time data of vehicle position. AVL systems allow companies to contact their vehicles any time, day or night, to determine current location and immediately retrieve other vehicle usage data. AVL systems allow greater control over the fleet management.
Actual position determination and relay techniques vary, depending on the needs of the transit system and the technology (or technologies) chosen. Typically, vehicle position information, its speed and direction are stored on the vehicle for a time, which can be as short as a few seconds or as long as several minutes. Position information can then be relayed to the control center in raw form or processed on-board the vehicle before its transmission.
The communication system for AVL could be via GSM or wireless network.
The GSM is ideal for GPS position information. GPS information is typically about 60 characters in length, leaving room for other information such as the vehicle registration details, average speed and so on to be transmitted as part of the same short message. The GSM again removes the cost of infrastructure and because here we use the existing cellular networks.
The disadvantage is the cost of using GSM services. If the messages have to be sent frequently, say every 15 seconds, the cost could propel. GSM costs could also increase with the use roaming services provided by the service provider.
Wireless networks are invariably established as a private network or one can use the existing wireless links at a cost. However there are various issues concerned with it.
The foremost is the licensing/payment issues in a country like India when one wants to set up a wireless network. Poor wireless coverage could lead to loss of data. The range of wireless network is also limited based on the size of the network. The cost of infrastructure is there but over a period of time and usage the cost effectiveness is increased.
Passive Fleet Management Systems
Passive Systems do not have real time transmission of data. An onboard memory within each vehicle logs the GPS tracking information and uploads it to an office-based PC on the vehicle’s return to base.
The passive system is designed more for companies that need to manage their fleets by reviewing the usage of the vehicles but does not need this information in real-time. Fleet managers often want to track information such as when and where delivery vehicles stop and for what duration or generate speeding reports.
Passive Systems are very cost effective. The passive system hardware is typically less expensive than the active system hardware and in addition, there are no ongoing airtime costs for SMS or the bother of a wireless network.
Screen Shot depicting attribute information for a location
Hybrid Fleet Management Systems
These combine both active and passive systems for companies that want the advanced management information available from passive solutions plus the ability to locate a vehicle instantly.
These systems are definitely more cost effective than AVL systems because here, there is the choice of polling location data at longer intervals cutting down on airtime costs and at the same time having access to detailed location data when the data is uploaded, on return, in the base station.