U.S. patent application number 09/911515 was filed with the patent office on 2002-02-14 for transferring accumulated data from vehicles.
This patent application is currently assigned to Minorplanet Limited. Invention is credited to Harrison, Christopher G., Morris, Jeffrey C..
Application Number | 20020019689 09/911515 |
Document ID | / |
Family ID | 26310054 |
Filed Date | 2002-02-14 |
United States Patent
Application |
20020019689 |
Kind Code |
A1 |
Harrison, Christopher G. ;
et al. |
February 14, 2002 |
Transferring accumulated data from vehicles
Abstract
Accumulated data is transferred from a plurality of vehicles to
a data processing station by transmitting a first packet type
request from each vehicle via an open radio channel in response to
a predetermined operation. This operation may include the vehicle's
ignition being turned off. The first packet type is detected at a
receiving station if a transmitting vehicle is within the vicinity
of the receiving station. The receiving station transmits an
instruction for data in the form of a second packet type upon
detecting a first packet type. Thereafter, a portion of the
accumulated data is transmitted from a detected vehicle in response
to instructions generated by the receiving station.
Inventors: |
Harrison, Christopher G.;
(Manchester, GB) ; Morris, Jeffrey C.; (Leeds,
GB) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
1100 North Glebe Road, 8th Floor
Arlington
VA
22201-4714
US
|
Assignee: |
Minorplanet Limited
|
Family ID: |
26310054 |
Appl. No.: |
09/911515 |
Filed: |
July 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
09911515 |
Jul 25, 2001 |
|
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|
09254880 |
Jun 9, 1999 |
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6278921 |
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Current U.S.
Class: |
701/33.4 |
Current CPC
Class: |
G08G 1/20 20130101; G07C
5/008 20130101; G08G 1/127 20130101; G01C 21/26 20130101 |
Class at
Publication: |
701/35 ;
701/33 |
International
Class: |
G06F 019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 1996 |
GB |
9619315.6 |
Jul 11, 1997 |
GB |
9714592.4 |
Sep 16, 1997 |
GB |
PCT/GB97/02519 |
Claims
1. A method of transferring accumulated data from a plurality of
vehicles to a data processing station, characterised by steps of
transmitting a first packet type request (431) from each vehicle
(401 to 405) via an open radio channel in response to a
predetermined operation; detecting said first packet type at a data
processing station (202) if a transmitting vehicle is within the
vicinity of said receiving station; transmitting an instruction for
data in the form of a second packet type (432) from said receiving
station (202) upon detecting said first packet type; and
transmitting a portion (433) of said accumulated data from a
detected vehicle in response to said instruction.
2. A method according to claim 1, wherein said accumulated data
(FIG. 7) represents vehicle positions.
3. A method according to claim 2, wherein said positional data is
derived by receiving radio signals from satellites.
4. A method according to any of claims 1 to 3, wherein said data
processing station includes a data collection point (406) for
receiving and transmitting radio signals and a data processing
system (202) for storing received data.
5. A method according to any of claims 1 to 4, wherein said
predetermined operation consists of the vehicle ignition being
turned off.
6. A method according to claim 5, wherein the accumulation device
records positional information when the ignition is turned on.
7. A method according to any of claims 1 to 6, wherein said first
packet type is transmitted after a relatively random period so as
to minimise the risk of two vehicles transmitting at the same
time.
8. A method according to any of claim 1 to 7, wherein accumulated
data may only be transmitted in response to an instruction from a
receiving station.
9. A method according to any of claims 1 to 8, wherein the size of
a transmitted portion (433) is restricted so that a packet
containing said data portion may not exceed a predetermined
size.
10. A method according to any of claims 1 to 9, wherein each radio
packet controller is arranged to examine its receiver to determine
whether any other transmissions are occurring, such that
transmissions are only made when the transmission frequency is not
being used by another device.
11. A method according to any of claims 1 to 10, wherein particular
accumulation devices mounted to particular vehicles are identified
by a unique address.
12. A method according to any of claims 1 to 11, wherein an
instruction (436) to clear memory is transmitted by said data
processing station after the final portion of accumulated data has
been received by said data processing station.
13. A method according to any of claims 1 to 12, wherein priority
is given to particular data accumulation devices or particular sets
of accumulation devices.
14. A method according to claim 13, wherein priority is given to
accumulation devices having relatively full memories.
15. A method according to any of claims 1 to 14, wherein positional
data is not recorded at specified times.
16. Apparatus for accumulating data at a vehicle (401 to 405) and
for transferring said accumulated data to a data processing
station, characterised by means (401) for transmitting a first
packet type (431) over an open radio channel to request
transmission of accumulated data; means for receiving an
instruction in the form of a second packet type (432) from a
receiving station (202) if the transmitter is within the vicinity
of said receiving station; and means (401) for transmitting a
portion (433) of said accumulated data in response to said received
instruction.
17. Apparatus according to claim 16, including means for
identifying the position of the vehicle and means for accumulating
data representing said positions.
18. Apparatus according to claim 17, wherein said means for
generating positional data includes means for receiving radio
signals from satellites.
19. Apparatus according to claim 16, including means for initiating
a transmission in response to the ignition of the vehicle being
turned off.
20. Apparatus according to claim 16, including means for
accumulating position information in response to the vehicle
ignition being turned on.
21. Apparatus according to claim 16, including means for
transmitting said first packet type after a relatively random
period so as to minimise the risk to vehicles transmitting data at
the same time.
22. Apparatus according to claim 16, including means for detecting
whether a radio channel is available prior to transmitting a packet
of data.
23. Apparatus according to claim 16, including means for recording
a unique address for the device.
24. Apparatus according to claim 16, including means for clearing
data accumulation memory in response to receiving an appropriate
instruction from a processing station.
25. A receiving station (202) for receiving accumulated data from a
plurality of vehicles, characterised by means for receiving a first
packet type request (431) from each vehicle via an open radio
channel; transmitting means (406) for transmitting an instruction
for data in the form of a second packet type (432) upon detecting
said first packet, wherein said receiving means is arranged to
receive portions (433) of said accumulated data from detected
vehicles in response to said instructions.
26. Apparatus according to claim 25, wherein said received data
represents vehicle positions.
27. Apparatus according to claim 25, including a data collection
point (406) for receiving and transmitting radio signals and a data
processing system for storing said received data.
28. Apparatus according to claim 25, including means for detecting
whether a radio channel is available prior to transmitting
instructions.
29. Apparatus according to claim 25, including means for
identifying unique addresses within received packets.
30. Apparatus according to claim 25, including means for
transmitting a packet instructing accumulation devices to clear
storage memory.
31. Apparatus according to claim 25, including means for
prioritising the accumulation of data from a plurality of
accumulation devices.
32. Apparatus according to claim 31, wherein said prioritising
means includes means for giving priority to accumulation devices
having relatively full memories.
Description
[0001] The present invention relates to transferring accumulated
data from a plurality of vehicles to a data processing station.
Introduction
[0002] Systems for transferring accumulated data from vehicles to a
data processing station are known and an example is illustrated in
international patent publication WO 90/09645. This publication
details a system in which sensors on each vehicle continuously
monitor sensed parameters, whereafter a record is made in a data
store under the control of a processing unit. The sensed data may
include road speed, engine speed, distance travelled, fuel
consumption, cylinder head temperature, exhaust gas temperature,
engine and transmission oil pressures and water temperature. The
recorded data is transmitted by radio to a base-station as desired.
The data may be transmitted automatically from each vehicle at
regular intervals of time or, alternatively, the data may be
transmitted when called or polled by a base-station and in a
described preferred embodiment, the vehicles are polled in turn on
demand or at regular intervals. The data, therefore, may be
transmitted by radio to the base-station while the vehicle is on
the road and, essentially, remote from said base-station.
[0003] A disadvantage of this known system is that a sophisticated
radio network is required in order to facilitate the transfer of
data. In many practical realisations, the cost of establishing such
a network would outweigh any commercial advantages given by the
monitoring system.
[0004] A hazardous waste shipment system is described in
international patent publication number WO 94/07225. The system
provides monitoring control to verify the location and condition of
each shipment. Two-way base stations receive status and
identification signals from vehicle-mounted transponders as the
shipments pass by and these base stations relay the information to
a central databank. The vehicle-mounted transponders may receive
data from sensors that monitor the load and may actuate alarms or a
message display for operator intervention. Notifications and safety
instructions are also provided in the event of a mishap and the
base station may relay instructions or route changes to the
vehicle-mounted transponders.
[0005] For the transportation of hazardous waste, a sophisticated
real-time transmission environment may be justified, given the
potential problems that may arise if anything goes wrong. However,
in many environments, such a sophisticated radio system could not
be justified and the provision of a network of base stations would
tend to be restricted to particular preferred routes.
[0006] A solution to the cost of establishing a radio network of
the type required in the aforesaid known system is put forward in
the United Kingdom patent publication number 2 288 892. In this
system, it is proposed to transfer data using an existing cellular
telephony networks which facilitate the transmission of data at
regular intervals. Consequently, a system of this type allows the
transmission of data in real-time such that, on a sample-by-sample
basis, the base-station receives information which may include fuel
consumption, global positioning and related parameters assisting in
the management of a fleet.
[0007] A system of this type is technically very attractive in
that, at any point in time, it is possible to establish the
position of all vehicles in the fleet. However, when this
information is transmitted, it is necessary to effect a telephone
call over a cellular or satellite radio network which, if samples
are obtained at regular intervals, would again significantly add to
the cost of operating the system. Consequently, using a system of
this type, it is likely that samples would be obtained after
relatively long periods thereby significantly reducing the
operational resolution.
[0008] A method of transferring accumulated data is described in
European Patent Publication No 0 239 066. This proposal avoids the
necessity for radio communications by accumulating data and
transferring the accumulated data in non-real time. The transfer is
made by storing the data in a removable device, preferably taking
the form of a key-fob. Thus, as a key is removed from an
operational vehicle, the data associated with that vehicle is
transferred with the key, thereby allowing the data to be
downloaded into a processing environment.
[0009] A problem with this known approach is that it requires the
physical transfer of a device in order for the accumulated data to
be downloaded. The physical size of the device will restrict the
amount of data which may be accumulated in this way and data loss
may also become a problem, given that the device must carry its own
source of power. Furthermore, the device must be robust and
requires specific activities to be performed on the part of drivers
and other operators in order for the data to be collected.
Summary of The Invention
[0010] According to a first aspect of the present invention, there
is provided a method of transferring accumulated data from a
plurality of vehicles to a data processing station, comprising
steps of transmitting a first packet type from each vehicle via an
open radio channel in response to a predetermined operation;
detecting said first packet type at a receiving station if a
transmitting vehicle is within the vicinity of said receiving
station; transmitting a request for data in the form of a second
packet type from said receiving station upon detecting said first
packet type; and transmitting a portion of said accumulated data
from a detected vehicle in response to said request.
[0011] An open radio channel is one in which radio transmissions
may be made without obtaining licenses and without using
fee-incurring service providers. Proprietary equipment is available
for use within these channels, operating at specified bandwidths
and it is appreciated that the range of operation is relatively
limited. Thus, a transfer of data only takes place when a vehicle
is within the vicinity of the receiving station. A plurality of
vehicles may download data in a multiplexed way. Only portions of
the accumulated data are transmitted so that any one vehicle is
only given access to the available bandwidth for relatively short
bursts. Furthermore, the transmission of data from a vehicle to the
receiving station is only possible after receiving an instruction
to transmit data from the receiving station. Preferably, the
accumulated data represents vehicle positions and said positional
data may be derived by receiving radio signals from satellites.
[0012] According to a second aspect of the present invention, there
is provided apparatus for accumulating data from a vehicle and for
transferring said accumulated data to a data processing station,
comprising means for transmitting a first packet type over an open
radio channel to request transmission of accumulated data; means
for receiving an instruction in the form of a second packet type
from a receiving station if the transmitter is within the vicinity
of said receiving station; and transmitting a portion of said
accumulated data in response to said received instruction.
[0013] Preferably, means are included for initiating a transmission
in response to the ignition of the vehicle being turned off.
Furthermore, means are preferably provided for accumulating
position information in response to the vehicle ignition being
turned on.
[0014] In a preferred embodiment, means are provided for
transmitting said packet type after a relatively random period so
as to minimise the risk of vehicles transmitting data at the same
time. Preferably, the apparatus includes means for detecting
whether a radio channel is available prior to transmitting a packet
of data.
[0015] According to a third aspect of the present invention, there
is provided a receiving station for receiving accumulated data from
a plurality of vehicles, comprising means for receiving a first
packet type request from each vehicle via an open radio channel;
transmitting means for transmitting an instruction for data in the
form of a second packet type upon detecting said first packet type;
and wherein said receiving means is arranged to receive portions of
said accumulated data from detected vehicles in response to said
instructions.
[0016] In a preferred embodiment, the apparatus includes means for
detecting whether a radio channel is available prior to
transmitting instructions. Preferably, the apparatus includes means
for identifying new unique addresses within received packets.
[0017] In a preferred embodiment, the apparatus includes means for
prioritising the accumulation of data from a plurality of
accumulation devices and said prioritising means may include means
for giving priority to accumulation device having relatively full
memories.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows a depot for commercial vehicles having a data
processing station and a data collection point;
[0019] FIG. 2 details the data processing station identified in
FIG. 2, including a communications interface, a data processing
system and a map of a geographical area of interest;
[0020] FIG. 3 details the map identified in FIG. 2, showing the
position of co-operating depots of the type identified in FIG.
1;
[0021] FIG. 4 schematically represents communications between data
accumulation devices, mounted in vehicles of the type shown in FIG.
1, the data collection point shown in FIG. 1 and the data
processing station identified in FIG. 2.
[0022] FIG. 5 details a data accumulation device of the type
illustrated in FIG. 4, including a micro-controller and a radio
packet controller;
[0023] FIG. 6 illustrates operations performed by the
micro-controller included in FIG. 5, including a data collection
process and a data download process;
[0024] FIG. 7 illustrates the formatting of data accumulated by the
data accumulation device shown in FIG. 5;
[0025] FIG. 8 details the data collection process identified in
FIG. 6, configured to store data using the format identified in
FIG. 7;
[0026] FIG. 9 illustrates the formatting of packets for application
to the radio packet controller shown in FIG. 5, under the data
downloading process identified in FIG. 6;
[0027] FIG. 10 identifies particular packet types assembled by data
accumulation devices of the type shown in FIG. 4;
[0028] FIG. 11 illustrates particular packet types assembled by the
data processing station illustrated in FIG. 4;
[0029] FIG. 12 details procedures performed by the micro-controller
shown in FIG. 5 for packet communication;
[0030] FIG. 13 details procedures effected by the data collection
point and the data processing station shown in FIG. 4 for packet
communication, including a step of writing data to a safe file;
[0031] FIG. 14 details the writing step identified in FIG. 13, in
which data is written to a plurality of files;
[0032] FIG. 15 identifies a table of files written to under the
procedures identified in FIG. 14; and
[0033] FIG. 16 shows further operations of the processing system
identified in FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] The invention will now be described by way of example only
with reference to the previously identified drawings.
[0035] It is has been appreciated for some time that the efficiency
with which fleets of vehicles are operated may be enhanced if
information about the vehicles may be collected and processed, so
as to facilitate planning and fleet management and also to ensure
that vehicles and their drivers are operating as intended. Ideally,
it would be preferable to continually relay information back from
vehicles to a central system so that information is instantaneously
available in real-time concerning parameters of interest. However,
the infrastructure resources required in order to achieve this
would often far outweigh any financial advantages gained from an
analysis of the information so obtained. Thus, for example, an
instantaneous real-time system is capable of identifying where
vehicles are. However, in many practical realisations, an operator
is more concerned as to where the vehicles have been. Consequently,
the present embodiment is concerned with the transfer of
accumulated data from a plurality of vehicles for subsequent
analysis.
[0036] The preferred embodiment is directed towards the
accumulation of positional information derived from global
positioning satellites, for which proprietary detection equipment
is readily available. However, it should be appreciated that other
types of data may be collected and the particular data sets
accumulated for subsequent downloading may be significantly
dependent upon the type of work being performed by the vehicles.
Thus, in addition to positional information, information may also
be accumulated relating to the mechanical operation of the vehicle
and the way in which the vehicle is being driven. In addition to
this, user specific information may be included which, for example
may relate very specifically to a particular emergency service,
possibly identifying particular modes of operation for that
service. Furthermore, systems of this type could be used to monitor
the use of the particular roads, for example where tolls are
required for using motorways, bridges and tunnels or when accessing
particular urban areas.
[0037] It can be seen that, particularly in emergency environments,
the information is considered to be of very high grade and
therefore a relatively high cost may be paid to effect the transfer
of this data. Similarly, much data may be seen as advantageous but
can only be realistically processed if the information may be
retrieved at modest cost and with little additional inconvenience
to operators and drivers. Ideally, and as achieved by the preferred
embodiment, the downloading of accumulated data is essentially
transparent to vehicle operators and, in this way, does not hinder
the professional activities of operators, while minimising
opportunities of mis-use.
[0038] A depot for commercial vehicles is illustrated in FIG. 1, in
which vehicles 101, 102, 103, 104 and 105 are examples of vehicles
which have been temporarily parked, possibly overnight, while their
drivers attend to other matters.
[0039] When vehicles are parked at designated areas within the
depot, they are within the vicinity of a data collection point 106
and each vehicle, in response to a predetermined operation such as
the vehicle ignition being turned off, will transmit a first packet
type request in an attempt to establish radio communication with a
data collection point 106.
[0040] The data collection point 106 communicates with a data
processing station housed, in the example shown in FIG. 1, within
office location 107 and a communication channel between data
collection point 106 and the data processing station 107 is
established, as appropriate, depending upon the distance between
these two locations. In combination, the data collection point and
the data processing station may be considered as a receiving
station which may detect packets of the aforesaid first type,
issued by a transmitting vehicle such that, in turn, they may
transmit an instruction for data in the form of a second packet
type. In response to receiving this second packet type, an
addressed vehicle may transmit a portion of its accumulated data
and this process may continue until a requesting vehicle has
downloaded all of its accumulated data.
[0041] As illustrated in FIG. 1, situations arise in which many
vehicles may wish to download accumulated data. This situation
arises more often than one may imagine, given that, very often,
vehicles will endeavour to reach a particular depot by a particular
time, possibly a lunch time or an end of shift etc. Even when
vehicles are covering relatively large distances, it is possible
that their journey may originate from a first depot and terminate
at a second depot. Again, even under these circumstances, it is
highly probable that the arrival of vehicles, with accumulated data
to transfer, will be relatively clustered such that, if the data
transfer is to be successful, the receiving station must be capable
of communicating and maintaining a conversation with many if not
all of the vehicles over a period of time. Furthermore, it is
appreciated that some vehicles may arrive at the depot for a
relatively short period of time and, if their accumulated data is
to be received, it is appreciated that transfers must not take too
long. Vehicles may also move within the depot therefore procedures
are required for re-establishing communications or establishing a
new communication without ambiguity. Similarly, sophisticated
procedures may be included for prioritising vehicles, possibly with
large amounts of data to download so as, overall, all of the
accumulated data is downloaded from the vehicles and the overall
integrity of the system is maintained.
[0042] The global positioning satellite system depends upon
twenty-four orbiting satellites of the NAVSTAR type space-based
radio navigation system. The satellites are placed in six orbital
planes at a distance of around 20,200 kilometres above the Earth's
surface. The satellites orbit with a twelve hour orbital period and
an inclination angle of 55 degrees. Each satellite broadcasts a
radio frequency signal at a centre of frequency of 1575.42
megahertz, known as the L1 band. The transmitted signal is
modulated by a 10.23 megahertz clock to provide a precise ranging
signal, in addition to a 1.023 megahertz clock, to provide a course
acquisition code ranging signal. At any time and at any position on
the Earth's surface, a minimum of five satellites are in line of
sight view. Provided that at least three satellites are within line
of sight, such that a receiver can receive a signal from said
satellites, it is possible for the GPS receiver equipment to
calculate the precise latitude and longitude positions of the
device on the Earth's surface.
[0043] Vehicles 101 and 102 are fitted with aerials 108 configured
to receive transmission from the GPS satellites such that
positional information, in terms of longitude and latitude, may be
determined from the received signals. At specified intervals within
the vehicle's journey, this information is recorded and accumulated
locally within the vehicle by means of a data accumulation
device.
[0044] When the ignition of a vehicle is turned off, the data
accumulation device will wait for twenty seconds before
broadcasting a request packet via a second aerial 109. If the
vehicle is within the vicinity of a data collection point 106, the
transmitted radio signal will be received by an aerial 110 at the
data collection point and relayed to the data processing station,
at location 107. This in turn may then initiate a conversation
between the data accumulation device and the data processing
station so as to effect a download of the data accumulated by the
vehicle.
[0045] Data collection point 106 includes a power supply 111
configured to supply power to a radio interface 112 and a
communications interface 113. The radio interface 112 is
substantially similar to data communication devices within the
vehicles and facilitates radio communication with said vehicles.
Communication to and from the radio interface is effected via a
conventional serial RS232 interface which in turn communicates with
the communication interface 113. Communications interface 113
provides for a current loop, transmitted via cables 114, so as to
facilitate communication with the processing station 107.
[0046] Processing station 107 is detailed in FIG. 2, arranged to
receive current loop cables 114 which are in turn supplied to a
second communications interface 201. Interface 201 includes a
serial RS232 interface which is in turn connected to a data
processing system 202, preferably operating under the control of
Windows NT or a similar multitasking operating environment.
[0047] The accumulation of data by the data processing system 202
may be effected essentially as a background process, thereby
allowing said system to be used, for example, for general purpose
office activities. In this way, the information is readily
available to an operator as and when required. The operator may
print results and maps etc via an appropriately interfaced laser
printer 203 and a map 204 of the geographical area of interest may
be made available for conventional marking etc.
[0048] Map 204 is detailed in FIG. 3. In this example, the fleet
operator has a main depot in Leeds 301, with subsidiary depots in
Brighton 302, Cambridge 303 and Swindon 304. At depots 302, 303 and
304 data may be collected from vehicles using equipment similar to
that shown in FIG. 1. However, the main data processing system is
present at location 301 and the information obtained from locations
302 to 304 is relayed to the station at location 301 over a public
telephony network. For example, the information could be relayed
over the Internet, over the PSTN or over an ISDN connection,
depending upon the quantity of data and the speed of transmission
required.
[0049] A vehicle may enter a depot belonging to another contractor
or may accidentally be in the vicinity of a data collection point
provided by another operator. Under these circumstances, the
vehicle would generate a first packet upon its ignition being
turned off. Data collection points in the vicinity would detect
this first packet but, subsequent analysis by an associated data
processing system would not recognise the calling packet therefore
no further download of information would be initiated and the
vehicle's accumulated data would not be cleared. All data
accumulation devices are provided with a unique address upon
manufacture and data processing stations are then programmed so as
to be aware of specific data accumulation devices sold or leased to
that particular customer.
[0050] Operation of the data accumulation and transmission system
is illustrated in FIG. 4. In this example, five data accumulation
devices 401, 402, 403, 404 and 405 have accumulated data to
transmit to a data collection point 406. The data collection 406
relays information to and receives information from data processing
system 202, having an output display device 408, an input device
409, a central processing unit 410 and a permanent storage device
411. The processing system communicates with the data collection
point via interface 201.
[0051] Each data accumulation device 401 to 405 transmits a packet
of type zero, shown schematically as 431, to the data collection
point 406. Information is relayed to the data processing system 202
which will first be checked to determine whether the accumulation
device belongs to its associated group of accumulation devices. If
this question is answered in the affirmative, to the effect that it
is legitimate for a download of information to take place, the data
processing system issues an instruction to the requesting
accumulation device in the form of a "send first packet"
instruction 432. Upon receiving this instruction the addressed
accumulation device issues its first packet of data, illustrated as
433. After receiving this first packet of data, the data processing
system issues a further instruction 434 instructing the addressed
accumulation device to send a second packet of data. The
accumulation device again responds to this instruction by sending
its second packet of data 435 and in this example it is assumed
that this represents the final packet of data. The data processing
system is aware of this being the final packet of data and
therefore subsequently issues an instruction 436 for the addressed
accumulation device to clear its memory, so that further data may
be accumulated on a subsequent trip.
[0052] The transfer of packets in FIG. 4 illustrates a conversation
between the data processing system 202 and one of the data
accumulation devices 401 to 405. The data processing system 202 is
configured to maintain many communications of this type and the
transmission of packets belonging to different conversations is
effectively multiplexed. This is achieved because, with the
exception of the type 1 data packet, requesting a conversation to
be established, all conversations are initiated by the processing
system 202. Thus, the data accumulation device may make a request
to initiate a conversation but, thereafter, it is the data
processing system which generates instructions and the data
accumulation devices may only respond after receiving such
instructions. Furthermore, the amount of data which may be supplied
in a single packet transmitted by a data accumulation device is
restricted such that no one data accumulation device may saturate
the available bandwidth and the distribution of transmission
bandwidth is maintained under the control of the data processing
system 202. In this way, the data processing system 202 may be
configured to allocate substantially similar bandwidth to the data
accumulation devices or it may include more sophisticated
instructions to identify prioritised accumulation devices, where an
attempt will be made to download information from these devices in
preferences to devices which are not considered to have such a high
priority. Thus, for example, the data processing system may give
priority to accumulation devices which have a relatively large
amount of data stored therein or priority may be given to
accumulation devices which are not seen very often.
[0053] Data accumulation device 401 is detailed in FIG. 5 and
includes a GPS receiver 501, a micro-controller 502, a radio packet
controller 503 and a data storage device 504. GPS receiver 501 is a
Rockwell Jupiter 12 channel device and the output from the GPS
receiver 501 is analysed by the microcontroller 502 which in turn
writes data, in the form of 24-bit words, to storage device 504.
The storage device includes battery back-up such that the integrity
of any stored data is maintained in case of vehicle power
failure.
[0054] The radio packet controller is typically an RPC 418
manufactured by Low Power Radio Solutions Limited of Witney,
Oxfordshire, GB. The controller includes a standing acoustic wave
FM transmitter in combination with a super-heterodyne receiver and
may operate upto a range of 120 meters over open ground. It is
configured to transmit packets having upto 27-bytes at a rate of 40
kilobits per second, half duplex. Packets of upto 27-bytes are
assembled by the micro-controller 502 and supplied to the radio
packet controller 503. The packet controller includes collision
avoidance measures such that it listens for other transmitted
packets before transmitting itself.
[0055] A data packet received by the radio packet controller 503 is
decoded and stored in a incoming packet buffer, whereupon the
micro-controller 502 is signalled, via an interrupt line, to the
effect that a valid packet is waiting.
[0056] Micro-controller 502 may be considered as being placed in
one of three operating conditions. When the vehicle ignition is on,
the microcontroller will endeavour to receive GPS information and
to store coded versions of this information within its storage
device 504. Data representing an initial start location is recorded
and, ultimately, a final stop location is recorded. During a
journey, positional information is recorded on a regular basis,
typically from one minute intervals upwards, with real-time
information being derived from the satellite signal every ten
minutes, every thirty minutes or every hour etc.
[0057] After the ignition of the vehicle is turned off, the
micro-controller will endeavour to download its stored information
via the radio packet controller. Such a downloading operation is
only successful if an initial packet, packet 431, is intercepted by
a data collection point, resulting in a packet similar to packet
432 being transmitted. If such a packet is not received by a data
accumulation device, packet 431 is re-transmitted after appropriate
intervals for an appropriate time-out period. These durations are
adjustable but, typically, a data accumulation device would attempt
to establish communication with a data collection point for a
period of approximately ten minutes. However, it is preferable to
introduce a degree of randomness in this process such that, when a
plurality of vehicles arrive at a depot substantially
simultaneously, they will not, even if turned off at the same time,
generate packets at the same time. This in turn will allow several
conversations to be multiplexed so as to ensure that a majority of
vehicles perform a data download.
[0058] Ultimately, after failing to download information, after a
download operation being interrupted or after a download operation
being successfully completed, the data accumulation device will
effectively enter a sleep mode, as identified at step 601 in FIG.
6.
[0059] The micro-controller 502 is interrupted by the vehicle's
ignition being switched on, resulting in control entering step 602
at which the processor enters a wake state. After an appropriate
wait, possibly in the region of ten seconds, the micro-controller
collects data at step 603. At step 604 a question is asked as to
whether the ignition is still on and if answered in the
affirmative, control is returned to step 603. Thus, upon each
iteration of step 603, an appropriate period of time elapses until
the specified collection time is reached. Upon reaching the
appropriate collection time, the position of the vehicle is
determined, from the information received from the GPS receiver 501
and an appropriate data entry is written to the storage device
504.
[0060] If the question asked at step 604 is answered in the
negative, the vehicle has been switched off, resulting in the
micro-controller 502 making an attempt to download data. A wait
state is entered at step 605, whereafter data download procedures
are effected at step 606.
[0061] After the transmission of each data packet, a question is
asked at step 607 as to whether the ignition has been turned on and
if answered in the affirmative, the micro-controller 502 is
redirected to its data collection process 603. Alternatively, if
the question asked at step 607 is answered in the negative, a
question is asked at step 608 as to whether the download is to
continue. This question will be answered in the negative if all of
the data has been transmitted or if communication with the data
collection point has been lost. When answered in the affirmative,
control is returned to step 606 and the downloading operation
continues. Alternatively, if the question asked at step 608 is
answered in the negative, control is returned to step 601 and the
micro-controller re-enters its sleep mode.
[0062] Positional data is written to storage device 504 as 24-bit
words. Each word represents a particular information type and a set
of information types is illustrated in FIG. 7. The information
types comprise a date 701, a start time 702, a stop time 703, an
absolute latitude 704, an absolute longitude 705 and a relative
latitude and longitude combined into a single 24-bit word, 706.
[0063] A first grouping of bits represents the information type,
with a second grouping representing the information itself and a
division between these two groupings is illustrated by line 707. An
absolute latitude 704 and an absolute longitude 705 require a total
of 22-bits, represented as T bits and G bits respectively. An
absolute longitude is identified by type code 10 and this
distinguishes it from an absolute longitude having type code
11.
[0064] After an absolute longitude and an absolute latitude have
been recorded, subsequent positional data is stored as a relative
latitude and longitude, by subtracting the absolute values
previously recorded from a present position. This provides a level
of compression such that only 11-bits are required for the relative
latitude with a further 11-bits being required for the relative
longitude. Thus, a word of this type is identified by word type
code 01.
[0065] Word type code 00 precedes the other three types of words
which are then uniquely defined by lower significant bits 17 to 21.
It can be appreciated that the provision of this number of bits for
identifying word types allows other types of words to be recorded,
which may be reserved for user-specific information. Thus, bits 17
and 18 are used to distinguish a date, a start time and a stop
time, with bits 0 to 16 being used to convey the associated
data.
[0066] A typical data set would be initiated with the recording of
the date. This would be followed by a start time which is then
followed by an absolute latitude and an absolute longitude. While
the vehicle remains in motion, relative values may be recorded and,
under normal operating conditions, words of type 706 would
constitute the bulk of the stored information; thereby obtaining
maximum advantage from the compression provided by this word type.
When the vehicle stops, the device would record a final absolute
latitude and an absolute longitude and the data set would be
terminated by a stop time and again the date. Thus, short journeys
result in relatively small data sets with larger journeys producing
larger data sets. However, during the recording and subsequent
downloading of information, it is not necessary for a vehicle
operator to interact with the apparatus in any way, thereby
reducing any additional burdens placed upon the driver while
significantly reducing the risk of the apparatus being
mis-used.
[0067] Process 603 for the collection of data, of the type
illustrated in FIG. 7, is detailed in FIG. 8. At step 801 a
question is asked as to whether this is the start of the journey,
which would be answered in the affirmative on the first iteration.
Consequently, the date (data type 701) and the start time (data of
type 702) are stored in storage device 504 at step 802. At step 803
the absolute latitude is stored and at step 804 the absolute
longitude is stored.
[0068] The processor will then enter a loop including wait state
806 until it is time, usually after a period of ten minutes, for
the next data entry to be recorded. Thus, after this period of
time, the question asked at step 805, as to whether it is time to
record data, will be answered in the affirmative, resulting in
control being directed to step 807.
[0069] At step 807 a question is asked as to whether the ignition
is on and if answered in the affirmative relative data, of type
706, is recorded at step 808. Thereafter, control is returned to
step 604 which in turn may result in control being directed to step
801, with the process being repeated. Thus, on the second and
subsequent iterations, the question asked at step 801 will be
answered in the negative, resulting in control being directed again
to step 805.
[0070] Eventually, the ignition will be turned off, resulting in a
question asked at step 807 being answered in the negative. Control
is directed to step 809, resulting in the stop time being recorded,
whereafter control is directed again to step 604, which will result
in control being directed to wait state 605.
[0071] Radio packet controller 503 is arranged to receive packets
containing upto a total of 27-bytes from the micro-controller 502.
Consequently, process 606, controlling the downloading of data, is
arranged to assemble data packets which conform to this format for
subsequent application to the radio packet controller 503.
[0072] The structure of packets which may be handled by the radio
packet controller 503 is illustrated in FIG. 9. Packets are
identified by 8-bit bytes and herein bytes are numbered from the
left starting at 1, whereas bits are number from the right starting
at zero. The transmitted packets may have a total of 27-bytes 901,
where the first byte B represents the total number of bytes
contained in the packet. The following four bytes 902 represent a
unique 4-byte address which is encoded into each data accumulation
device, of the type shown in FIG. 5, during the manufacturing
process. This ensures that all data accumulation devices are
unique, such that it is not possible for data to be downloaded at
an inappropriate site.
[0073] The 4-byte address 902 is followed by a 1-byte packet type
T, at byte location 6, followed by a 2-byte number N which will
usually represent the packet number. This is then followed by upto
18-bytes of data, bytes 9 to 26, followed by a check sum S at byte
location 27 or at the final byte location for a packet containing
less than 27-bytes.
[0074] The 18-bytes of data are considered in the embodiment as six
24-bit blocks, identified as blocks n, n+1, n+2, n+3, n+4 and n+5.
Thus, each packet transmitted by the radio packet controller may
contain a total of six blocks of the type illustrated in FIG. 7.
Sometimes less than six blocks of data may be available and, under
these circumstances a data packet is transmitted having less than
27-bytes.
[0075] Packet types transmitted by the radio packet controller 503,
of a data accumulation device, are illustrated in FIG. 10. These
consist of packet type zero, shown as 1001, which is equivalent to
packet type zero shown in FIG. 4 as 431. Packets 1002, 1003, 1004,
1005, 1006 and 1007 are all packet types three, where packet 1002
contains six data blocks 1011, 1012, 1013, 1014, 1015 and 1016.
Thus, transmitted block 433 shown in FIG. 4 would be a data block
of type 1002, whereas the final data block, shown as 435, could be
of any types 102 to 107, depending upon the amount of data
remaining to be transmitted.
[0076] Block type 1001, identifying that a data accumulation device
has data to download, consists of a total of 9-bytes, therefore the
first transmitted byte identifies this total number. As for all
transmitted packets, the subsequent 4-bytes identify the unique
address of an accumulation device and the sixth byte identifies the
packet type which, in this example, is of type zero.
[0077] For packet type zero, shown at 1001, bytes 7 and 8 represent
the total number of data blocks, that is 24-bit blocks of the type
shown in FIG. 7, stored at the data accumulation device. This
information informs the data processing station as to how many
blocks of data are to be expected. With this information, the data
processing station is made aware as to when a transfer has
completed. It will know the size of the final packet and it will
know when to transmit a clear memory packet. Similarly, it will
also know if a data download has been prematurely terminated and,
with this information, it may also prioritise a downloading process
so that priority is given to vehicles having relatively full
memories. As for all the transmitted packets, packet 1001 is
terminated with a check sum.
[0078] For data packets, such as packets 1002 to 1007, bytes 7 and
8 are used to identify the packet number. Thus, a first transmitted
data packet would be identified as packet one, with subsequent
packets being identified sequentially. In this way, it is possible
for the data processing station to ensure that all packets have
been received and to take appropriate action if one of the expected
packets is missing. Under some circumstances, the data processing
system may ignore a missing packet. During the middle of a journey,
for example, lost data may be interpolated from surrounding data.
Alternatively, if a packet is lost, the download may be terminated
without clearing memory, such that the system will wait for an
appropriate opportunity to initiate the download sequence again. In
an alternative more sophisticated embodiment, the data processing
station may issue a request for a lost packet to be retransmitted
and such requests and retransmitted packets may be identified with
appropriate packet types.
[0079] Packet types transmitted by the data processing system are
illustrated in FIG. 11. These packets are of relatively short
duration, given that they are merely issuing instructions to the
data accumulation devices and do not transmit data as such.
[0080] Packet type 1101 instructs an addressed data accumulation
unit to send a particular packet. The data accumulation unit
instructed is identified by 4-bytes address 1102, followed by byte
position 6 identifying the packet as a type two packet. After
receiving this information, the addressed accumulation device
understands the packet type as being an instruction to transmit a
particular packet and the particular packet to be transmitted is
identified by packet number 1103 at byte positions 7 and 8. This is
then followed by the check sum byte given a total packet length of
9-bytes.
[0081] Packets 1104 instructs a data accumulation unit to confirm
that it is still active and still has data to transmit. If the data
processing station performs a time-out, to the effect that it has
not received information back from a data accumulation unit for an
unacceptable period of time, a packet of type 1104 may be
transmitted, identified as a packet of packet type 1, which may
result in a packet of packet type zero being retransmitted by the
data accumulation device. Eventually, after several packets of this
type being transmitted, the data processing system may assume that
communication has been terminated and take appropriate action.
Packet type 4 is illustrated at 1105 and consists of the
instruction, identified by byte location 6, for the addressed data
accumulation unit to clear its memory. This completes the download
procedure and results in a data accumulation unit being in a
position to reuse its memory for new positional data.
[0082] Procedures 606 for the downloading of data, using the packet
protocol shown in FIG. 10, are detailed in FIG. 12.
[0083] At step 1201 a question is asked as to whether data is
present in storage device 504 and if answered in the affirmative a
calculation is made as to the number of data blocks present within
storage device 504. Having determined the number of 24-bit data
blocks b present within the storage device 504, the number of
packets N required to download this data is calculated at step
1203. This value is divided by six and the remainder identifies the
type of the final packet to be transmitted, taken from the set 1002
to 1007.
[0084] Having made the calculations through steps 1202 to 1204, it
is possible for the download process to be initiated. At step 1205
a packet of type zero is transmitted making a request to initiate
data download. A question is asked at step 1206 as to whether a
response has been received and if answered in the negative, a
question is asked as to whether the process should try again. If
answered in the affirmative, control is returned to step 1205 and a
packet of type zero is transmitted again. If after several attempts
no response is received, the question asked at step 1207 will be
answered in the negative and the download will terminate.
[0085] If a response to the transmission of packet type zero is
received, resulting in the question asked at step 1206 being
answered in the affirmative, control is directed to step 1208,
resulting in the first packet of type three being downloaded to the
receiving station. Again, the accumulation devices asks, at step
1209, whether a response has been received and if no further
instructions are received, the micro-controller 502 will again time
out and the download operation will terminate.
[0086] If a response is received, the question asked at step 1209
is answered in the affirmative and a question is then asked as to
whether it is a type two instruction, requesting more data, or a
type four instruction, instructing the micro-controller to clear
its storage device 504. Thus, a question is asked at step 1211 as
to whether a type two instruction has been received. This question
is answered in the affirmative, control is returned to step 1208
and a packet of type three is transmitted again. Alternatively, if
the question asked at step 1211 is answered in the negative, a
question is asked at step 1212 as to whether a type four
instruction has been transmitted and, in this embodiment, having
answered question 1211 in the negative, question 1212 should be
answered in the affirmative, resulting in the memory being cleared
at step 1213.
[0087] The data processing system 201, 202 and the data collection
point 106 may be considered in combination as the data collection
base-station. Operations performed by this combination are
summarised in FIG. 13.
[0088] At step 1301 an encoded packet is received at the collection
point 106, which in turn demodulates this packet at step 1302 into
a 27-byte or less packet. These bytes of data are encoded into
ASCII representations to facilitate transmission of conventional
interfaces.
[0089] At step 1304 the ASCII data is transmitted over the current
loop 114 and reconverted at interface 201 into conventional serial
interface (RS 232) ASCII bytes. The ASCII bytes are transmitted to
the processing system 202 at step 1305 and at step 1306 received
data is written to a safe file. Preferably, this file exists in
randomly accessible memory within the processing system 202 so as
to ensure that the data is quickly recorded during the transmission
process. Thereafter, this volatile file is backed-up onto permanent
storage 411 within the processing system 202.
[0090] A question is asked at step 1308 as to whether the session
has ended and if answered in the negative, a packet of type two is
transmitted as an instruction for subsequent data to be downloaded.
Alternatively, when the question asked at step 1308 is answered in
the affirmative, a packet of type four is transmitted at step 1310,
instructing the originating data accumulation device to clear its
associated memory.
[0091] Operations performed by the data processing system 202 are
complicated by the fact that it may be communicating with many data
accumulation devices. However, this multi-tasking situation is
facilitated by a multi-tasking operating system and the
multiplexing of transmission is controlled because all data
transfers can only take place after the data processing system has
supplied an instruction for a data packet to be downloaded.
[0092] The 24-bit blocks of data are written to the safe file,
resulting in a collection of data substantially similar originally
recorded by the accumulation devices. Each accumulation device is
allocated its own specific file path, although several files may be
generated for individual accumulation devices which are
subsequently combined during an operation of posting the
accumulated data to a relational database.
[0093] Operations performed by data processing system 202 are shown
in FIG. 14. The operations are initiated in response to a packet of
information being received from interface device 201.
Alternatively, in less sophisticated embodiments, the data may be
received directly from radio interface 112, subject to the length
of the transmission distance.
[0094] Upon receiving a packet of information, the data processing
system enters a wait state at step 1401. When activated to handle
data transmissions of this type, the data processing system 202 is
relatively fast and therefore wait states are incurred in order to
bring its operational times more into line with the packet
transmission times over the radio interface. In this way, the speed
at which the data processing system handles radio communications is
slowed down, thereby ensuring that the radio interface does not
become too congested. The duration of wait state 1401 is determined
empirically and effectively provides a balance between the number
of data accumulation devices which may wish to download data
simultaneously, the available radio bandwidth and the processing
speed of the data processing system 202.
[0095] At step 1402 the address (bytes 2 to 5) of an incoming
packet are considered and a question is asked to determine whether
the vehicle belongs to the system's group. If this question is
answered in the negative, no further action is taken and
communication ceases.
[0096] If a received packet does belong to the group, the question
asked at step 1402 is answered in the affirmative and a question is
then asked at step 1403 as to whether a conversation has already
been established.
[0097] On receiving a first packet type zero, informing the data
processing station that an accumulation device has data to
transmit, the question asked at step 1403 will be answered in the
negative, resulting in a new safe file being created at step 1401,
with details being added to a mapping list as illustrated in FIG.
15. If a question asked at step 1403 is answered in the
affirmative, to the effect that a file does exist, control is
directed to step 1405.
[0098] At step 1405 the safe file associated with the particular
data accumulation device (as specified by it's address) is
identified and at step 1406 the data blocks are extracted from the
transmitted packet. These extracted data blocks are written to the
respective safe file at step 1407 and at step 1408 a time stamp is
applied to the file mapping, identifying the time at which the last
write operation was effected to said safe file.
[0099] At step 1409 all of the time stamps are considered and if
any of the stamps are seen as being too old, it is assumed that a
communication has terminated and appropriate action is take at step
1410. Thus, at step 1410, entries identified at step 1409 may be
deleted from the file mapping. The data may be retained, in the
hope that it may be added to later or, alternatively, the data may
be deleted such that a complete download will be required
subsequently. The system may include provisions to identify
absolute positional data and to delete information received after
the last absolute position.
[0100] A file mapping is illustrated in FIG. 15, which may be
established as a linked list, so as to optimise memory
availability. When a new data accumulation address is identified,
an entry is placed in column 1501. The new entry is allocated a new
safe file which, as shown in FIG. 15 and as listed at column 1502,
consists of a directory path file, followed by a unique file name.
The files are shown written to drive L, a logical random access
memory drive, whereafter completed files are written to associated
permanent storage, usually identified as drive C.
[0101] The associated time stamp is shown at column 1503,
containing information representing minutes, seconds and fractions
of seconds. This information is derived from the real-time system
clock and merely represents the time at which the safe file was
last updated. Thus, the time stamp provides a provision by which
the system can determine when the file was last written to and if
file writes have not occurred for a predetermined time, action may
be taken to revive a communication, by the transmission of a packet
of type 1104 (type 1) as shown in FIG. 11 or the communication may
be terminated altogether.
[0102] After data has been collected as illustrated in FIG. 15, the
data may be present in permanent storage in a form substantially
similar to that form in which it was collected by the data
accumulation devices. Having collected this information, many types
of processing may be effected upon it in order to record and
display the information in appropriate forms.
[0103] Firstly, referring to FIG. 3, data of this type, recorded at
remote location 303, 302 and 304, may be transmitted to the main
depot at location 301. At location 301, all of the data may be
accumulated together, effectively in a form such that it is
indistinguishable from data received locally. It is not necessary
to distinguish data received from remote locations because of the
nature of the data itself, representing geographical positions,
will clearly identify where a download took place. However, should
any ambiguity arise, it is possible to include additional data
types added to the data representing a download location.
[0104] At the main data processing station, it is possible for data
tasks to run concurrently with data collection exercises, as
described above, and with other general purpose applications.
[0105] Preferably, the data is posted from the safe files to a
relational database, as shown at step 1601. The database may take
substantially conventional form and may be built upon standard
applications, such as PARADOX.TM. or ACCESS.TM. etc. The data
recorded by the GPS system identifies locations in terms of global
longitudes and latitudes. In each country, this information may be
converted into national grid references at step 1601, such that the
information contained within the database may be related to other
geographical entities.
[0106] At step 1602 the position of vehicles may be displayed on an
interactive map, possibly shown on a monitor associated with system
202, as shown in FIG. 2. With this provision in place, the need for
maintaining manual maps, as illustrated at 204, becomes
significantly reduced.
[0107] At step 1603, recorded information in the form of graphical
maps or textural lists, may be printed by means of laser printer
203.
* * * * *