Implementing
a
Vehicle Fleet Tracking System
with GPS
Author: Steven Potter
© Spottek Systems 2007
Abstract
This Learning Object is intended to give a very basic explanation of how the
GPS system works, with a brief description of how GPS might be used, with a
digital radio communications network, a database, and a mapping application,
to implement a vehicle fleet tracking system.
It is expected that the audience would not be directly involved in implementing
such a system, but would need to know what resources might be needed to do
so.
(Note: This presentation will take about six minutes of your time)
What is needed to implement a GPS based
Vehicle Fleet Tracking System?
•
Each vehicle in the fleet needs to be able to determine and report its position
GPS receiver
Network Digital Radio
•
Network base station collects and records vehicle position reports
Vehicle Identification
Date and time
Position data/coordinates
Database
•
Vehicle Information Database to manage information for vehicle fleet
In addition to data collected from vehicle radio network - could include
Driver identification
Driver or vehicle, or both, scheduling data
Vehicle maintenance schedules, logs
•
Mapping application
Query database for vehicle position data
Plot vehicle(s) on a map
GPS Overview
The technology derived from the use of
the GPS (Global Positioning System),
and related systems, has made it
possible to use very accurate position
data, in real-time.
Based on a network of 24 Earth-orbiting
satellites, and dependent on atomic timekeeping devices (Ref 2), the GPS, first
developed for the US military, has
become a ubiquitous navigation and
positioning tool.
All of the GPS based, real-time,
positioning systems operate by collecting
very accurately time-stamped, relative,
position data from a number of orbiting
satellites, and computing a position in 3dimensional space, on the Earth’s
surface.
{Adapted from Ref 1}
GPS: How it works
At regular intervals, each satellite
sends its position, in 3-dimensional
space, and a time code, representing
the precise time that the satellite was
located at that position.
A receiver can calculate its distance
from each satellite position, by
computing the time taken for a
satellite’s signal to reach it.
The receiver’s position, relative to
each satellite, must be on the surface
of a sphere with a radius of the
computed distance, with the satellite
at the sphere’s center.
{Adapted from Ref 3}
GPS: How it works
The relative position
spheres from two
satellites, will
intersect in a circle.
{Adapted from Ref 3}
GPS: How it works
The position sphere from a
third satellite will intersect the
circle at two points.
The position sphere from a
fourth satellite will intersect one
of those two points, revealing
the position of the receiver.
(Note: If a receiver is known to be on the
Earth’s surface, which is very nearly a perfect
sphere, only three satellite signals are
needed to determine the receiver’s position)
{Adapted from Ref 4}
Vehicle Fleet Tracking System
Each vehicle in the fleet is fitted
with a GPS receiver and a Network
Radio
Periodically, each vehicle reports
its position to the Base (Control)
station.
(There are a variety of methods for this,
depending on the type of radio network
employed)
Vehicle Fleet Tracking System
The Base Station collects
Vehicle Identification,
Date and Time,
and Position data,
and maintains a
Vehicle Information Database
Vehicle Fleet Tracking System
A mapping application
can query the database
for vehicle position data
and plot vehicle positions
onto a city street map.
(Note that similar systems can be used
to track trucks, planes or ships, on a
larger scale)
References
1.
“The GPS Toolkit”
http://interactive.linuxjournal.com/article/7467
Linux Journal
2.
“The Global Positioning System: The Role of Atomic Clocks”
http://www.beyonddiscovery.org/content/view.page.asp?I=1275
Beyond Discovery
3.
How [GPS] works
http://www.trimble.com/gps/howgps-triangulating.shtml
Trimble
4.
GPS: the Mathematics and the Technology
http://mail.colonial.net/~abeckwith/gps.html
Anthony Beckwith: Advanced topics in Mathematics
© Spottek Systems 2007