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What is claimed is:
1. A mobile unit for a vehicle monitoring system, the mobile unit
comprising:
a) an input unit, responsive to an event or condition associated with the
vehicle, and providing information describing the event or condition;
b) a satellite receiver, responsive to navigation signals transmitted by a
satellite navigation system, and providing information inherently
describing the vehicle's location based on the navigation signals; and
c) a mobile unit controller, responsive to the input unit and the satellite
receiver, the mobile unit controller including a cellular telephone
transmitter for transmitting information onto a cellular telephone
communications link, the information transmitted on the cellular telephone
communications link including both (1) the information describing the
event or condition and (2) the information inherently describing the
vehicle's location, the mobile unit controller automatically inserting the
information describing the vehicle's location into the information
transmitted onto the cellular telephone communications link.
2. The mobile unit of claim 1, wherein the input unit includes:
an operator input device which, when activated by a vehicle operator,
causes the mobile unit controller to transmit a message onto the
communications link while automatically inserting the information
describing the vehicle's location into the transmitted information with
the message.
3. The mobile unit of claim 2, wherein:
the operator input device includes a keypad including keys whose closure is
detected by the mobile unit controller; and
the mobile unit controller transmits a message corresponding to the
particular key or keys the operator has closed.
4. The mobile unit of claim 3, wherein:
the mobile unit controller transmits a message constituting a request for
assistance corresponding to a sequence of key closures.
5. The mobile unit of claim 1, wherein the input unit includes;
an alarm system including at least one sensor that automatically detects
the event or condition associated with the vehicle and causes the mobile
unit controller to transmit an alarm message onto the communications link
while automatically inserting the information describing the vehicle's
location into the transmitted information with the alarm message.
6. A mobile unit for a vehicle monitoring system, the mobile unit
comprising:
a) a vehicle alarm system, responsive to an alarm event or alarm condition
associated with the vehicle, and providing information describing the
alarm event or alarm condition;
b) a satellite receiver, responsive to navigation signals transmitted by a
satellite navigation system, and providing information inherently
describing the vehicle's location based on the navigation signals; and
c) a mobile unit controller, responsive to the vehicle alarm system and the
satellite receiver, the mobile unit controller transmitting information
onto a communications link, the information transmitted on the
communications link including both (1) the information describing the
alarm event or alarm condition and (2) the information inherently
describing the vehicle's location, the mobile unit controller
automatically inserting the information inherently describing the
vehicle's location into the information transmitted onto the
communications link.
7. A mobile unit for a vehicle monitoring system, the mobile unit
comprising:
a) an input unit, responsive to an event or condition associated with the
vehicle, and providing information describing the vent or condition;
b) a location unit providing information inherently describing the
vehicle's location;
c) a cellular telephone transmitter including means for forming a decision
as to whether or not the transmitter is in range of a cellular telephone
network, and transmitting information onto a cellular telephone
communications link only when the transmitter is in range of a cellular
telephone network; and
d) a mobile unit controller, responsive to the input unit and ht location
unit, the mobile unit controller including:
1) a storage device, the storage device including a storage area for
storing both (1) the information describing the event or condition and (2)
the information inherently describing the vehicle's location in
association with each other; and
2) a processor, interacting with the cellular telephone transmitter and
controlling the storage device in response to the decision as to whether
or not the transmitter is in range of a cellular telephone network, the
processor performing the functions of:
i) storing in the storage device (1) the information describing the event
or condition and (2) the information inherently describing the vehicle's
location in association with each other, when the transmitter is not in
range of a cellular telephone network; and
ii) retrieving from the storage device (1) the information describing the
event or condition and (2) the information inherently describing the
vehicle's location in association with each other, when the transmitter is
in range of a cellular telephone network.
8. A mobile unit for a vehicle monitoring system, the mobile unit
comprising:
1) an operator input device having a number of inputs characterizing only
approximately four distinct predetermined messages, the operator input
device providing information describing a chosen message when one or more
inputs relating to the chosen message are activated by an operator;
2) a satellite receiver, responsive to navigation signals transmitted by a
satellite navigation system, and providing information inherently
describing the vehicle's location based on the navigation signals; and
3) a mobile unit controller, responsive to the operator input device and
the satellite receiver, the mobile unit controller transmitting
information onto a communications link, the information transmitted on the
communications link including both (1) the information describing the
chosen message and (2) the information inherently describing the vehicle's
location, the mobile unit controller automatically inserting the
information describing the vehicle's location into the information
transmitted onto the communications link.
9. A control center for a vehicle monitoring system having a plurality of
mobile units mounted in respective vehicles and a communications link
between the mobile units and the control center, the control center
comprising:
a) a control center display portion including:
1) one or more display screens displaying one or more maps with symbols of
vehicles sending messages to the control center; and
2) real-time display software allowing the symbols of the vehicles sending
messages to be displayed substantially in real-time;
b) at least about eight communications interface devices coupled to the
communications link, receiving sporadically-timed messages from the mobile
units, and outputting the messages; and
c) a control center buffer portion coupled to the control center display
portion, the buffer portion responsive to the messages output by the
communications interface devices and the buffer portion including:
1) means for examining the messages received for determining if the
messages pass or fail the examination;
2) means for generating individual responses to the messages received from
respective vehicle mobile units based on the examination of the messages,
the means for generating individual responses being coupled to forward the
individual responses to the communications link and to the control center
display portion; and
3) means for providing to the control center display portion certain
messages that have passed the examination, the messages allowing the
real-time display software to display the symbols of the vehicles sending
the messages that have passed the examination.
10. A vehicle monitoring system comprising:
a) an ambulatory operator input device means for an operator to carry away
from a vehicle, the ambulatory operator input device means providing
information describing a message when activated by the operator; and
b) a mobile unit means for attachment to a vehicle, the mobile unit means
including:
1) a local receiver including means to communicate with the ambulatory
operator input device means, the local receiver receiving the message when
activated by the operator;
2) a location unit providing information inherently describing the
vehicle's location; and
3) a mobile unit controller, responsive to the local receiver and the
location unit, the mobile unit controller transmitting information onto a
communications link, the information transmitted on the communications
link including both (1) the message and (2) the information inherently
describing the vehicle's location, the mobile unit controller
automatically inserting the information inherently describing the
vehicle's location into the information transmitted onto the
communications link.
11. A control center for a vehicle monitoring system having a plurality of
mobile units mounted in respective vehicles and a communications link
between the mobile units and the control center, the control center
comprising:
a) a control center display portion, including display screens displaying
one or more maps with symbols of vehicles sending messages to the control
center;
b) a satellite reference receiver, responsive to navigation signals
transmitted by a satellite navigation system, and providing information
inherently describing the control center's location based on the
navigation signals; and
c) a control center communications controller, the control center
communications controller being responsive to messages received from the
mobile units, the communications controller being coupled to the control
center display portion and to the satellite receiver, the communications
controller including:
1) means for extracting, from the messages received from the mobile units,
vehicle position information that is derived from vehicle position
information provided by a mobile unit satellite receiver receiving
navigation signals transmitted by the satellite navigation system;
2) means for adjusting the vehicle position information in accordance with
a drift error correction term derived from the navigation signals, to
provide adjusted vehicle position information; and
3) means for providing to the control center display portion the adjusted
vehicle position information so that the control center display portion
displays the symbols of the vehicles on the one or more maps in accordance
with the drift error correction term. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems for monitoring vehicles. More
specifically, the invention relates to a multi-featured system for
monitoring the status of vehicles, detecting certain alarm conditions,
monitoring the location of vehicles, and providing a variety of
communication and control functions relating to the vehicles.
2. Related Art
The Federal Bureau of Investigation reports that a vehicle theft occurs
somewhere in the United States every 20 seconds. The National Auto Theft
Bureau (NATB) estimates that one of every 42 vehicles in the United States
is stolen or broken into, or has parts, contents, or accessories stolen,
resulting in an estimated loss of over $9 billion per year. Law
enforcement officials concede that theft of the vehicle and its contents
is one of the easiest crimes to commit, and one of the most difficult to
prevent and solve. Authorities estimate that an experienced auto thief can
break into almost any vehicle in as little as six seconds, regardless of
whether or not it has an alarm system. On average, fewer than one in five
of the vehicles stolen in the United States is recovered and the thief
prosecuted. Clearly, known alarm systems do not stop determined,
experienced motor vehicle thieves.
Various anti-theft devices are known in the art. The simplest devices take
the form of physical restraints, such as door locks, steering wheel bars,
or wheel locks. More sophisticated systems involve passive alarms that
activate automatically when the driver leaves the car.
More recently, electronic homing devices have been developed that can track
a vehicle, but only after it is reported stolen. After the vehicle is
discovered to be stolen and reported to police, the police are able to
track and capture the thief, provided the vehicle owner and the police
have both invested in special communications devices. In addition to being
useful only after the vehicle is reported stolen, these systems are useful
only in the geographical areas where the corresponding police receivers
are located. Moreover, these systems are in some cases prohibitively
expensive.
Therefore, there is a need in the art to provide a cost-effective automatic
vehicle theft detection device which immediately alerts the police to the
theft, allowing them to track the vehicle over a wide geographic area.
On a related matter, breakdowns, accidents, and medical and other
emergencies in a motor vehicle may arise. Clearly, it is desirable to be
able to quickly and conveniently report the emergency occurrence and
request appropriate assistance. For example, it is desirable to contact a
wrecker, ambulance, fire truck, or police as needed, and indicate the
exact location where assistance is needed. The presence of citizens band
radios or cellular telephones has increased, but these systems suffer from
shortcomings such as the inability to accurately relay the vehicle's
position.
Therefore, there is a need in the art to provide a system which can quickly
summon appropriate vehicles such as a wrecker, ambulance, fire truck, or
police, and reliably and accurately communicate the location where the
assistance is needed.
On still another related issue, companies such as courier services and
freight hauling firms have always had a need for tracking the vehicles in
their fleets. By tracking the fleet vehicles, a dispatcher knows which
vehicle is the most appropriate one to send to a next location, thus
improving overall fleet efficiency. It is desirable to provide information
on the status of each vehicle in the fleet, such as whether it is moving,
parked, or disabled. This comprehensive information allows the dispatcher
to use an existing fleet to its greatest advantage, thereby providing
better service to the company's customers. Unfortunately, known fleet
monitoring systems have often involved two-way voice communications
depending on the dispatcher's communication with a large number of
drivers, resulting in less than optimum efficiency and reliability.
Therefore, there is a need in the art to provide a fleet tracking system
which provides a dispatcher with continuously updated comprehensive
information about the variety of vehicles in a fleet.
The present invention provides a vehicle tracking and security system which
overcomes the shortcomings of the known systems.
SUMMARY OF THE INVENTION
The present invention provides a vehicle tracking and security system which
provides round-the-clock vehicle security, allowing immediate response in
case of vehicle theft, an accident, vehicle breakdown, or other emergency.
Guardian and tracking functions are provided through Mobile Units which are
preferably installed in hidden locations in vehicles to be monitored. The
Mobile Units communicate with a Control Center in at least one-way, and
preferably two-way, communication. Preferably, the Mobile Unit provides
vehicle theft and intrusion protection using a in-vehicle alarm and
security system linked to the Control Center by a transceiver in the
Mobile Unit. Also, a keypad or other human interface device is provided in
the vehicle, allowing a vehicle driver or occupant to signal the Control
Center that a particular type of assistance is needed. The vehicle's
location may be automatically transmitted to the Control Center along with
any automatic or manual request, the location being precisely determinable
anywhere in the world. In this manner, the present invention provides
continuous monitoring of a large number of vehicles for a broad range of
status and emergency conditions over a virtually unlimited geographic
area, also allowing manual communication of requests for assistance to
that specific location. Advantageously, the system is implemented using
existing location-detection systems and conventional commercial or police
communications equipment.
According to a first aspect of the invention, there is provided a mobile
unit for a vehicle monitoring system, the mobile unit having an input unit
responsive to an event or condition associated with the vehicle, and
providing information describing the event or condition. The mobile unit
also has a satellite receiver (preferably GPS), responsive to navigation
signals transmitted by a satellite navigation system, and providing
information describing the vehicle's location based on the navigation
signals. Also, the mobile unit has a mobile unit controller, responsive to
the input unit and the satellite receiver, the mobile unit controller
including a cellular telephone transmitter for transmitting information
onto a cellular telephone communications link, the information transmitted
on the cellular telephone communications link including both (1) the
information describing the event or condition and (2) the information
describing the vehicle's location, the mobile unit controller
automatically inserting the information describing the vehicle's location
into the information transmitted onto the cellular telephone
communications link.
According to another aspect of the invention, there is provided a mobile
unit for a vehicle monitoring system, the mobile unit having a vehicle
alarm system, responsive to an alarm event or alarm condition associated
with the vehicle, and providing information describing the alarm event or
alarm condition. The mobile unit also has a satellite receiver, responsive
to navigation signals transmitted by a satellite navigation system, and
providing information describing the vehicle's location based on the
navigation signals. The mobile unit also has a mobile unit controller,
responsive to the vehicle alarm system and the satellite receiver, the
mobile unit controller transmitting information onto a communications
link, the information transmitted on the communications link including
both (1) the information describing the alarm event or alarm condition and
(2) the information describing the vehicle's location, the mobile unit
controller automatically inserting the information describing the
vehicle's location into the information transmitted onto the
communications link.
The invention further provides a mobile unit for a vehicle monitoring
system, the mobile unit having an input unit, responsive to an event or
condition associated with the vehicle, and providing information
describing the event or condition, and a location unit providing
information describing the vehicle's location. The mobile unit also has a
cellular telephone transmitter including means for determining whether or
not the transmitter is in range of a cellular telephone network, and
transmitting information onto a cellular telephone communications link
when the transmitter is in range of a cellular telephone network. The
mobile unit has a mobile unit controller, responsive to the input unit and
the location unit. The mobile unit controller has a storage device, the
storage device including a storage area for storing both (1) the
information describing the event or condition and (2) the information
describing the vehicle's location in association with each other; and a
processor, interacting with the cellular telephone transmitter and
controlling the storage device. The processor performs the functions of i)
storing in the storage device (1) the information describing the event or
condition and (2) the information describing the vehicle's location in
association with each other, when the transmitter is not in range of a
cellular telephone network; and ii) retrieving from the storage device (1)
the information describing the event or condition and (2) the information
describing the vehicle's location in association with each other, when the
transmitter is in range of a cellular telephone network.
The invention also provides a mobile unit for a vehicle monitoring system,
the mobile unit having an operator input device having a number of inputs
characterizing approximately four distinct predetermined messages, the
operator input device providing information describing a chosen message
when one or more inputs relating to the chosen message are activated by an
operator. The mobile unit also has a satellite receiver, responsive to
navigation signals transmitted by a satellite navigation system, and
providing information describing the vehicle's location based on the
navigation signals. The mobile unit also has a mobile unit controller,
responsive to the operator input device and the satellite receiver, the
mobile unit controller transmitting information onto a communications
link, the information transmitted on the communications link including
both (1) the information describing the chosen message and (2) the
information describing the vehicle's location, the mobile unit controller
automatically inserting the information describing the vehicle's location
into the information transmitted onto the communications link.
The invention also provides a control center for a vehicle monitoring
system having mobile units mounted in respective vehicles and a
communications link between the mobile units and the control center. The
control center has a control center display portion including one or more
display screens displaying one or more maps with symbols of vehicles
sending messages to the control center; and real-time display software
allowing the symbols of the vehicles sending messages to be displayed
substantially in real-time. The control center also has at least about
eight communications interface devices coupled to the communications link,
receiving sporadically-timed messages from the mobile units, and
outputting the messages. The control center also has a control center
buffer portion coupled to the control center display portion, the buffer
portion responsive to the messages output by the communications interface
devices. The buffer portion includes means for examining the messages
received, means for generating individual responses to the messages
received from respective vehicle mobile units based on the examination of
the messages, the means for generating individual responses being coupled
to the communications link and to the control center display portion, and
means for providing to the control center display portion certain messages
that have passed the examination, the messages allowing the real-time
display software to display the symbols of the vehicles sending the
messages that have passed the examination.
The invention also provides a vehicle monitoring system having an
ambulatory operator input device adapted for an operator to carry away
from a vehicle, the ambulatory operator input device providing information
describing a message when activated by the operator. The monitoring system
also has a mobile unit adapted for attachment to a vehicle. The mobile
unit includes a local receiver including means to communicate with the
ambulatory operator input device, the local receiver receiving the message
when activated by the operator; a location unit providing information
describing the vehicle's location; and a mobile unit controller,
responsive to the local receiver and the location unit, the mobile unit
controller transmitting information onto a communications link, the
information transmitted on the communications link including both (1) the
message and (2) the information describing the vehicle's location, the
mobile unit controller automatically inserting the information describing
the vehicle's location into the information transmitted onto the
communications link.
The invention also provides a control center for a vehicle monitoring
system having a plurality of mobile units mounted in respective vehicles
and a communications link between the mobile units and the control center.
The control center includes a control center display portion, including
display screens displaying one or more maps with symbols of vehicles
sending messages to the control center. The control center also has a
satellite reference receiver, responsive to navigation signals transmitted
by a satellite navigation system, and providing information describing the
control center's location based on the navigation signals. The control
center has a control center communications controller, the control center
communications controller being responsive to messages received from the
mobile units and coupled to the control center display portion and to the
satellite receiver. The communications controller includes means for
extracting from the messages received vehicle position information that is
derived from vehicle position information provided by a mobile unit
satellite receiver receiving navigation signals transmitted by the
satellite navigation system; means for adjusting the vehicle position
information in accordance with a drift error correction term derived from
the navigation signals, to provide adjusted vehicle position information;
and means for providing to the control center display portion the adjusted
vehicle position information s that the control center display portion
displays the symbols of the vehicles on the one or more maps in accordance
with the drift error correction term.
Other objects, features, and advantages of the present invention will
become apparent on reading the following Detailed Description in
conjunction with the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is better understood by reading the following Detailed
Description of the Preferred Embodiments with reference to the
accompanying drawing figures, in which like reference numerals refer to
like elements throughout, and in which:
FIG. 1 is a high-level block diagram of the preferred vehicle tracking and
security system according to the present invention.
FIG. 2A and 2B constitute a block diagram which schematically illustrates
further details of the preferred Mobile Unit of FIG. 1. FIG. 2A and 2B are
collectively referred to herein as "FIG. 2."
FIG. 3 is a diagram illustrating components of a preferred Mobile Unit as
including various sensing, power, and data input devices.
FIG. 4 is a perspective drawing of a vehicle using the elements of FIG. 3.
FIG. 5 illustrates a preferred keypad for use with the preferred Mobile
Unit.
FIG. 6 is a flow chart illustrating operation of the preferred Mobile Unit
in Idle Mode.
FIG. 7 is a flow chart of the operation of the preferred Mobile Unit in
Assist Mode.
FIGS. 8A and 8B are flow charts illustrating operation of the preferred
Mobile Unit in Alarm Mode.
FIG. 9 is a flow chart illustrating operation of the preferred Mobile Unit
in Telephone Mode.
FIGS. 10A and 10B are flow charts illustrating operation of the preferred
Control Center.
FIG. 11 illustrates an exemplary "General Area Coverage Map" as it might be
displayed to a Control Center operator.
FIG. 12 illustrates an exemplary COMMAND MENU for the preferred
communications controller in the Control Center.
FIG. 13 illustrates an exemplary display controller CONTROL MENU
superimposed on a map, as displayed to the Control Center operator.
FIG. 14 illustrates an exemplary MOTORIST ASSISTANCE SERVICES menu
superimposed on a map, as displayed to the Control Center operator after
being accessed from the CONTROL MENU of FIG. 13.
FIG. 15 illustrates an exemplary CALL STATUS menu superimposed on a map, as
displayed to the Control Center operator after being accessed via the
CONTROL MENU of FIG. 13.
FIG. 16 illustrates an exemplary vehicle CALL HISTORY superimposed on a
map, as displayed to the Control Center operator after being accessed via
FIG. 15.
FIG. 17 illustrates an exemplary CALL CONTROL menu, superimposed on a map,
as displayed to the Control Center operator after being accessed via FIG.
15
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In describing preferred embodiments of the present invention illustrated in
the drawings, specific terminology is employed for the sake of clarity.
However, the invention is not intended to be limited to the specific
terminology so selected, and it is to be understood that each specific
element includes all technical equivalents which operate in a similar
manner to accomplish a similar purpose.
Stated generally, the invention is a multi-featured electronic tracking and
security system which includes devices that calculate a vehicle's
position, detect local events, and calculate a system response based on
weighted variables. Based on the calculated response, the system notifies
the vehicle occupants. In certain circumstances, the system notifies a
Control Center via a preferably two-way communication channel, to allow
the Control Center to respond appropriately such as by summoning emergency
vehicles or remotely controlling the vehicle in some way. Provision of a
two-way communication system allows the Control Center to positively
verify the message which was sent by the vehicle.
The preferred embodiment of the present invention provides computerized
graphic maps which display vehicle locations using information ultimately
derived from the existing Global Positioning System (GPS), thereby
providing a highly accurate, real-time vehicle tracking system. The
preferred system provides an integrated location system, communication
network, mapping system, and dispatch capability. The system is especially
suitable for use in fleet vehicle management, vehicle theft deterrent,
stolen vehicle tracking, railroad car tracking, cargo location, and so
forth. The system may be customized to a particular user's needs and, due
to the preferred embodiment's use of the GPS, may be installed and used
virtually anywhere in the world.
Referring to FIG. 1, the invention involves a set of "Mobile Units"
100A-100E which are provided on respective vehicles 102A-102E that are to
be monitored, protected, or tracked. A communications link 110 is provided
between the Mobile Units (hereinafter collectively indicated 100) and a
"Control Center" 150 which is manned by one or more trained operators 152.
The Mobile Unit may automatically detect certain status and alarm
conditions, or a driver or passenger in the vehicle may manually request
certain assistance, both of which actions may be immediately communicated
to the Control Center along with automatically generated GPS-derived
positioning data. The Control Center operator may take action as
appropriate, including dispatching of emergency vehicles 160, 162, 164,
166, 168, commanding the appropriate Mobile Unit 100 to repeatedly
transmit position data, or ignoring the Mobile Unit's communication.
Certain functions may be either automated or manually controlled by the
Control Center operator, such as whether the vehicle horn is sounded in
response to an unexpected motion sensor activation indicating theft of the
vehicle.
In particular, the vehicles may include a conventional passenger automobile
102A, a set of fleet vehicles 102B, 102C, 102D (such as buses or other
mass transit vehicles, courier vehicles, delivery vehicles, utility
vehicles, sanitation trucks, armored cars, police cars, rental cars, and
so forth), as well as a train 102E. The communications link 110 is
preferably implemented as a conventional cellular telephone link, but of
course need not be so limited. The Control Center 150 may appropriately
summon help in the form of police 160, a fire truck 162, an ambulance 164,
a wrecker 166, or other appropriate help, generally indicated as element
168. Each Mobile Unit 100 preferably includes means for determining the
present location of the vehicle 102 in which it is installed. Preferably,
this means for determining the location is a Global Positioning System
(GPS) receiver, not only for its accuracy but because the location
information transmitted from GPS satellites is provided free of cost.
As readily appreciated by those skilled in the art, the GPS was developed
by the U.S. Department of Defense and placed into service in the 1980's.
The GPS includes a constellation of radio-navigation satellites which
constantly transmit precise timing and location information to
substantially the entire surface of the earth. The GPS receiver in the
Mobile Unit is preferably implemented using a multi-channel GPS receiver
so as to acquire many (for example, five) transmissions from a
corresponding plurality of GPS satellites simultaneously. This allows the
Mobile Unit to determine the location of the vehicle (within approximately
20 meters), velocity (to within 0.1 mph), and direction of motion, for
possible transmission to the Control Center 150. Various GPS satellites
are schematically illustrated at 120A, 120B. The Control Center 150 is
equipped with a reference GPS receiver 154 to provide selectable real-time
error correction of the measurements of the locations of the vehicles,
using differential GPS techniques.
The reference GPS receiver 154 allows for real-time correction of GPS
errors. By determining "drift" in the GPS signals, the output of the
reference GPS receiver effectively provides a correction factor which may
be subtracted from the position data transmitted by the vehicles.
Preferably, a time history of the GPS "drift" is stored in the
communications controller, so that any information stored in a Mobile Unit
but transmitted at a later time may be properly correlated with earlier
"drift" information for correction. According to a preferred embodiment,
the drift correction algorithm may be switched on and off by the
communications controller operator, so as to cause the incoming
measurements to be corrected, or not corrected, based on operator choice.
The present invention preferably use a simple "difference GPS" adjustment,
in contrast to the known "differential GPS" correction which is more
costly and complex. The reference GPS receiver may be of the same,
economical type used in the mobile units, in contrast to the costly units
used in differential GPS systems. The Control Center difference GPS
adjustment involves subtraction of the drift in the (known) location of
the Control Center from location information transmitted by the mobile
units. This unidirectional data flow is in contrast to differential GPS
systems which derive and transmit a correction factor to the mobile unit,
which mobile unit then applies the correction factor before transmitting
back a corrected location.
The Control Center 150 includes a communication controller 170 and a
display controller 180, there being a suitable conventional interface 190
therebetween. For example, the interface 190 may be a local area network
(LAN) interface, having one or more terminals 192 allowing control center
operator 152 to enter information into the controllers. Terminals 192 are
understood to include any of a variety of input devices such as a
keyboard, mouse, trackball, or other user interfaces.
The preferred Control Center includes a plurality of modems 172A . . . 172H
disposed between the communications link 110 and the communications
controller. In the illustrated embodiment, the modems 172A . . . 172H
provide an interface between conventional telephone lines and a
communications controller processor within communications controller 170.
The communications controller 170 serves as a buffer between the Mobile
Units 100 and the display controller 180. Data passing through the
communications controller 170, as well as general communications status
information, is displayed on a communications display 174. The display
controller 180 is provided with a plurality, preferably four, mapping
displays 182A, 182B, 182C, and 182D. The mapping displays, collectively
referred to as element 182, display information regarding the vehicles in
a graphic manner, such as on pre-existing digitized maps of arbitrarily
large geographical areas.
Based on information displayed on mapping displays 182, or noted on the
communications display 174, the Control Center operator 152 may contact
the police 160, fire department 162, ambulance 164, wrecker 168, or other
suitable emergency vehicle 168, on a dispatch means 176. The dispatch
means 176 may be an ordinary telephone for manual dialling by a human
operator, or it may be any other suitable means of rapidly communicating
with the emergency services. For example, any conventional means for
automatically dialling a pre-programmed telephone number may be used, with
the communications controller providing the order to call a given number.
More elaborate embodiments involve message delivery systems to communicate
particular messages to the telephone number thus called, thus bypassing
the human operator if the system designer so desires. Thus, the dispatch
means 176 may be connected to the communications controller 170 so that,
under controlled circumstances, the emergency services may be summoned
automatically, without intervention of the Control Center operator 152.
However, in most practical embodiments, it is preferred that the display
controller 180 simply provide information on a mapping display 182B, 182C
or 182D, so that the operator may exercise human judgment before an
emergency service is called.
The structure of the preferred embodiment of the Mobile Unit is described
below, with reference to FIGS. 2, 3, 4 and 5. Operation of the Mobile
Units in conjunction with the Control Center is explained with reference
to FIGS. 6-9. Operation of the Control Center in conjunction with the
Mobile Units is described with reference to FIGS. 10A-17.
FIG. 2 illustrates a preferred Mobile Unit controller 200 in conjunction
with various other elements within a preferred Mobile Unit 100. FIG. 2
illustrates major components of the Mobile Unit, it being understood that
conventional elements whose functions are not critical to an understanding
of the present invention are omitted. For example, optical isolators,
level translators, crystal oscillators, buffers, bus transceivers,
drivers, protection circuits, voltage regulators, and other auxiliary
functional circuits are omitted from FIG. 2 and the present specification,
for the sake of clarity. Those skilled in the art are readily capable of
implementing the present invention, given the present discussion. The
elements which are schematically illustrated in FIG. 2 are presented
literally in FIG. 3.
FIG. 3 is a perspective view, partially exploded, of the components of the
preferred Mobile Unit 100. The main component of Mobile Unit 100 is Mobile
Unit controller box 200'. Mobile Unit controller box 200' is housed in a
chassis 302 with a chassis lid 304. The components of Mobile Unit
controller box 200' are held together and connected by commonly available
hardware 306 and a suitable wiring harness 308.
The essential components in the Mobile Unit controller box are a controller
PC board 310, a power PC board 312, a commercially available GPS (Global
Positioning System) receiver 314, and a suitable transceiver (such as a
commercially available cellular telephone transceiver) 316. To preserve
the data contents of volatile memory in the Mobile Unit controller, a
memory back-up battery 318 is provided. The Mobile Unit controller 200, as
such, is not considered to include the GPS receiver or transceiver,
although the boards for these devices are shown in FIG. 3 to be in the
Mobile Unit controller box 200'.
A global positioning system antenna 314A is provided, external to the
Mobile Unit controller 200. The GPS antenna 314A is connected to the GpS
receiver 314.
An optional auxiliary position determination unit 390 is provided, to
provide position information when the GPS receiver is not functioning
properly o when the vehicle is in a "blank area" in which an insufficient
number of GPS satellite signals are being received with acceptable signal
quality. The auxiliary position determination unit may also be employed
when a "bad data" bit is set in the GPS receiver, indicating that, for
some reason, transmissions received by the GPS receiver are not yielding
accurate or meaningful results.
The auxiliary position determination unit 390 may itself comprise a
microcomputer of conventional design, with suitable bus and communication
interface structures. The auxiliary position determination unit 390 is
connected to microcomputer 202 through a suitable interface, such as
RS-232 interface 290I.
Connected to the auxiliary positioning determination unit 390 are one or
more devices allowing extrapolation of position based o position and
direction data previously provided through the GPS receiver 314. For
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