GB2375270A

GB2375270A - Monitoring movement

Info

Publication number: GB2375270A
Application number: GB0204688A
Authority: GB
Inventors: Andrew Walters
Original assignee: QUARTIX Ltd
Current assignee: QUARTIX Ltd
Priority date: 2001-05-04
Filing date: 2002-02-28
Publication date: 2002-11-06
Anticipated expiration: 2022-02-28
Also published as: GB0110970D0; GB2375270B; GB0204688D0

Abstract

There is provided a method of monitoring a movable body (12), comprising detecting a first event associated with the body and acquiring first event data relating to the first event, compressing the first event data, placing the first event data in the first segment of a text message, placing event data relating to subsequent events in successive segments, and transmitting the text message to a host facility. There is also provided position monitoring apparatus comprising a data acquisition device (56) e.g. GPS receiver, data compressing means (56) and transceiver means (50, 54, 80, 82) for communicating with a host facility (14). Acquired data may be compressed by converting the data into Base 80.

Description

Title : Method and Apparatus for Monitoring Movement Field of Invention This invention relates to a method and apparatus monitoring movement of a body, such as a vehicle, and in particular where such monitoring is undertaken using the global system for mobile communication (GSM).

Background to the Invention Vehicle monitoring systems for logging vehicle movements are known. Generally these systems rely on GSM networks with the position of a vehicle recorded in data processors on board the vehicle for subsequent transfer to a central monitoring station, such as a computer.

Data relating to a vehicle's movements can be transferred using a detachable data logging device, such as a key fob, or by radio transmission. Systems using SMS text messaging have also been proposed.

However, a single commercial vehicle having its position monitored throughout a day's journey generates a large amount of data for transfer. This increases costs associated with obtaining positional information relating to the vehicle over the day.

It is an aim of the present invention to overcome the disadvantages of the existing systems by reducing the amount of data transfer required.

Summary of the Invention In accordance with one aspect of the present invention, there is provided a method of monitoring a movable body, such as a vehicle, comprising detecting a first event associated with the body and acquiring first event data relating to the first event, compressing the first event data, placing the first event data in a first segment of a text message, placing event data relating to subsequent events in successive segments, and transmitting the text message to a

host facility. Each text message may be transmitted separately via a GSM network to a host facility, or may be stored within a file as a number of messages for subsequent transmission by file transfer at the end of a day, or may be transmitted singly or within a file when requested via a host facility.

The method allows for selective acquisition of data relating to the movable body which reduces the amount of data that needs to be transmitted to describe a vehicle's travel throughout a day. Acquisition of data is only stimulated in response to specific events such as ignition, excess speed, excess period of idling, change of bearing, rapid change in speed, which occur at random indeterminate times as they relate to external conditions affecting the vehicle which cannot be predicted. Thus one cannot know when a driver will start up the ignition, or how traffic volume will affect travel on any given day.

Preferably the method further comprises maintaining a moving average of vehicle speed and heading, typically over consecutive 30 second periods.

Compression of the event data is preferably achieved by converting the data into base 80.

This records the data in a compressed way as, for example, fewer digits are required to write a number in base 80 than in ordinary decimal.

A first code describing the first event is preferably placed at the beginning of the first segment, with the remainder of the segment comprising the first event data, and subsequent codes used in successive segments to describe subsequent events. Thus a code may describe an excess period at or above maximum speed, with the event data describing the position, velocity (i. e. bearing and speed), or the code may describe a change of direction of a vehicle at a junction, with the event data describing the position, bearing and speed at a certain point in time following the change in direction.

The compression of data before writing into a segment of text message allows the text message to contain data relating to many different events. Each text message acts as a log of data over a period of time determined by the frequency with which detected events are written to the message. Thus snapshots of data relating to the movable body are acquired in

response to stimuli such as ignition, excess speed, change of heading, rapid change in speed etc. Selectively acquiring data in this way allows a text message to record a plurality of events occurring over 60-90 minutes, or if desired over an entire day if loss of fine detail relating to the vehicle's movements is acceptable. As a result, large amounts of data do not need to be downloaded either throughout the day, or at the end of the day.

The method preferably further comprises checking time elapsed after movement of the body has ceased, and stimulating transmission of a text message once the body has been stationary, for example, for two hours. This ensures that download of information is stimulated even when the text message is not completed with event data.

The invention also lies in a position monitoring apparatus comprising a data acquisition device, data compressing means, and transceiver means for communicating with a host facility. Communication may be via a GSM network.

The data acquisition device is preferably an integrated GPS receiver and processor, such as the Rockwell Jupiter Flash GPS which has an integral 16-bit processor. This allows data to be acquired and analysed on board a moving body before transmission.

The apparatus preferably further comprises means for placing the data acquisition device in a quiescent or stand-by mode. Typically this is provided by the processor of the GPS receiver which monitors the period of time for which the vehicle is stationary and the ignition turned off. The processor initiates the transmission of a message, together with any stored messages, before placing the receiver in a quiescent state. Reinitialisation and reset is triggered by a monitoring circuit connected to an ignition line leading into the receiver/processor.

Inputs to the data acquisition device are preferably fed via opto-isolation circuitry.

The invention also lies in a system for monitoring a movable body, comprising apparatus as aforesaid, and a host facility, wherein the host facility communicates with the apparatus using text messages and files. Communication may be via a GSM network. The host

facility allows analysis of data from the body once such data is downloaded into the host facility.

The invention will now be described, by way of example, and with reference to the accompanying drawings, in which: Figure I shows a schematic representation of a vehicle monitoring system in accordance with the present invention ; Figure 2 shows a schematic diagram of vehicle monitoring apparatus in accordance with the present invention; Figure 3 shows a flow diagram describing steps in a vehicle monitoring method in accordance with the present invention, and which uses a text message to transmit data relating to a vehicle; Figure 4 shows a schematic representation of part a text message; and Figure 5 shows a completed text message ready for transmission.

Description A vehicle monitoring system is shown at Figure 1 which uses the global system for mobile communication (GSM) network and the public switched telephone network (PSTN) 10 to relay information between a vehicle 12 and a host facility 14, such as a computer server, which is accessible to parties 16 wishing to monitor the vehicle's movements. The vehicle carries data acquisition and transfer equipment, discussed later with reference to Figure 2, which communicates with the host facility 14 via the GSM/PSTN 10 network using SMS text messages. The on-board equipment uses satellite positioning signals 18,20 to determine the vehicle position with reference to a fixed origin and combines this with other information relating to the vehicle in a text message for subsequent transmission. Each text message provides information on vehicle movement and events occurring to the vehicle, such as ignition being initiated, over a given period of time with a number of successive messages describing a vehicle's travel history over a day. Each text message is either transferred immediately or stored with other text messages for subsequent transfer to the host facility 14 via the GSM/PSTN network 10, and information is transferable between the host facility and the vehicle by use of text messages or asynchronous file transfer.

The host facility 14 comprises various recording and processing elements which allow data relating to the vehicle to be presented in an appropriate format for access by a customer's computer terminal over the internet via modem or other appropriate link. Thus typically the host facility 14 comprises a main server and archive 22 which incorporates a relational database 24 connected to an IP connection 26 and an ISDN modem bank 30. The ISDN modem bank 30 can transfer files on ISDN via the GSM/PSTN network to or from the vehicle. This asynchronous file transfer using either the message protocol described later with reference to Figures 3 to 5 and Tables 1 to 3 or a standard file transfer protocol such as Kermit or Xmodem, and provides a second way of communicating with the vehicle, ie. in addition to the use of SMS text messages. The relational database 24 is directly linked to an internet web server and has a two-way connection with a web site and a report generator 32 hosted by the main server 22 which is accessible by the customer 16 for email/fax reports on vehicle activity, live tracking of vehicle movements and allows data entry by the customer 16 to request specific information from the server 22.

The monitoring system provides customers with precise reports on the activity of each vehicle in a customer's fleet allowing customers to log vehicle movements, check driver overtime payments, private mileage, costing estimates, arrival times at customer site, vehicle speed, and other information relating to the vehicle. This allows for improved productivity and logistical planning.

As shown in Figure 2, the data acquisition and transfer equipment is in the form of a terminal device 40 which comprises a unitary housing holding 42 a carrier board 44 on which is mounted the individual elements required for data acquisition and transfer. This provides a secure tamper-resistant module for securing inside a vehicle. The terminal device 40 is powered using an input 46 from the vehicle battery and a DC/DC converter 50 accepting input from either a 12V or 24V battery and producing a 5 volt output.

On the carrier board 44, a GPS receiver 50 is connected via an RS232 connection 52 to a () GSM modem module 54, such as the Siemens"TC35. The GPS receiver incorporates a 16-bit A

processor, and such an integrated unit 56 is provided by Rockwell under the Trade Mark

Jupiter Flash. Data inputs 60,62, 64 from the vehicle into the GPS receiver and processor 56 are fed through opto-isolation circuitry 66 before entering the GPS receiver and processor 56. The data inputs comprise an ignition line 60 and a plurality of additional input lines 62, 64, typically two, which can be connected to sensors in the vehicle to acquire information on other events of interest, for example a security alarm, a high or low temperature within a refrigerated compartment carried by the vehicle, or the vehicle idling. This integrated GPS receiver and processor 56 is connected to the power supply via a watchdog circuit 70 which forms one input 72 to a processor trigger and reset circuit 74. The ignition line is connected to a second input 76 of the processor trigger and reset circuit 74, so that the processor is only powered when the vehicle engine is running, or for a set time after the ignition has been switched off as determined by the reset circuit 74. The GPS receiver 50 and GSM modem module 54 are each connected to a respective antenna 80,82 so as to provide a dual GPS/GSM antenna for communication with the GSM/PSTN network 10.

When in use, the GPS receiver 50 receives signals from four or more GPS satellites and using the processor, computes and monitors the vehicle's velocity (speed and bearing) or when its heading changes by more than a certain amount, and where required altitude. The absolute position of the vehicle is stored for each event carried in the text message, with data stored in the text message only in the event of certain exceptional conditions, such as when the vehicle stops or begins motion, or its speed exceeds certain upper or lower limits. Thus storing of data only occurs at random intervals in response to random triggering events related to the vehicle, the processor acting as a selective data logger, and not by periodic acquisition. For example, as will be explained later in more detail, the absolute position, speed and bearing will be stored when an event such as ignition occurs. Further data will not be recorded until the vehicle undergoes another triggering event, such as the engine being switched off. This limits the amount of data needed to describe a vehicle's journey and yet still provides sufficient information for an observer interested in monitoring the vehicle's movements as when the vehicle stops/starts or other factors of interest such as when a speed limit is exceeded are the main factors affecting delivery or pick-up of goods by the vehicle.

The accumulation and transmission of data from the vehicle will now be described with reference to Figures 3 to 5.

The processor 56 is set to be in a quiescent mode when a vehicle engine is not running, and is activated to acquire data by the hardware trigger (processor trigger and reset circuit) 74 which responds to an electrical signal on the ignition line 60, when ignition occurs. The steps undertaken within the processor 56 once it is activated are set out in Figure 3. After activation 90, the processor creates a new text message 92 and places a vehicle identification segment at the start of the message. The processor 56 then monitors and detects defined events 94 occurring to the vehicle 12, such as ignition, certain speeds etc. and once a defined event has been detected, records data 96 associated with this event, for example speed, bearing, accumulated distance etc, for subsequent transmission as an SMS text message.

The data is processed on-board the vehicle 12 by converting the data into Base 80 and encoding it as ASCII text characters in the range 0x30 to Ox7F 100. The resulting data compression allows a given text message to contain information relating to many types of event that occur throughout a day's journey, so that typically only five or six text messages need to be transmitted to describe a full day's travel with numerous stops and starts. After compression of the data into Base 80 and encoding as ASCII text, the character (s) describing the event that has occurred and data relating to that event is stored in a character array in the program memory 102, and in a first event segment of the text message.

Subsequent events and their data are written into the text message in successive segments in the text message. Once the text message reaches 145 characters, the message is closed for recording any more events, has alternative characters substituted for non-transmissable text, and a checksum is added in a last segment. The entire message is then transmitted over the GSM network 10 or stored in the vehicle monitoring system for subsequent transmission in a batch of messages to the host facility 14.

A time-check 104 is incorporated, such that if the ignition has been switched off for more than two hours, the text message is closed 106 for onward transmission over the GSM network 10 to a server 22. The transmission of the text message results in the hardware trigger 74 cutting off the power supply to the processor 56, and the processor entering the quiescent mode 110.

If the ignition is switched off, but has not been switched off for longer than two hours 112, then the same text message is used for the monitoring of other events until the text message reaches more than 145 characters at which point the message is closed and transmitted 114 over the GSM network 10 to the server 22 as before.

Acquisition of data and the writing of this into a text message will now be described in more detail.' Switching the ignition on activates the processor 56 and the type of event, namely ignition, is noted. As the vehicle 12 moves, once a second the processor 56 notes the speed and integrates over time to get the distance travelled. Data relating to position, speed and bearing is accumulated in a number of different registers. A moving average of both speed and heading is maintained over two consecutive 30 second periods (based on results taken each second). The following event types are recorded: (i) A change in moving average speed by more than 40km/hr (i. e. a difference in the averages of the two 30 second periods by this amount) (ii) An average speed of less than lOkm/hr over the entire 60 seconds (iii) A change in moving average heading by more than 60 degrees between these two 30 second periods.

Events are recorded as a result of one of the above, or as a result of the vehicle travelling a certain distance.

After the processor is activated, on-board processing of data relating to the event, as stored in the registers, then begins. Firstly the data is compressed by converting it into Base 80 format so that as many data points as possible can be contained within one message. For SMS messages, each message is 160 bytes in length and rather than compress a final message into 160 characters, the available ASCII character set within the text message is used to record individual data points in a compressed way. Thus the numbers are presented written in Base 80 and encoded to fit within the printable characters set within ASCII 48 and 127.

Typically each event and information acquired relating to that event is contained within a segment of the text message, for example 10 bytes, with 6 bytes representing the absolute position of the vehicle. However, using the method of the invention, 14 or 15 events, together with related information, can be held within one text message so that over the course of a day only 5-6 text messages are required to describe all the events that have occurred to a vehicle. The amount of journey time that a single text message covers varies depending on the events that have occurred to the vehicle, and thus generation of successive text messages does not occur at specific defined intervals but rather depends on the event history of the vehicle.

Using the text mode of SMS provides an inexpensive way to transfer data and guarantees delivery of the message. This is because a connection does not need to be established between the onboard transmitter and receiver, i. e. server, rather the message is stored on a SIM smart card and transmitted when the onboard device has network access. However the text mode of SMS has a number of severe limitations for data transfer, namely : 1. Messages are limited to 160 characters only.

2. Only 7-bit ASCII characters are supported.

3. The interpretation of control codes in the GSM network means that only the characters between 32 and 127 (decimal) are useful for data.

4. There are frequently holes in the interpretation of the available characters. Most networks do not correctly interpret codes between 91 and 96, or between 123 and 127. For example, " {" is converted into" (", with a consequent change in the ASCII code which leads to certain misinterpretation.

5. The cost can be quite high for large amounts of data treated in this way.

The range of ASCII codes that can be used within the text message are thus 32-127 and these are divided into three groups as shown in Table I below:

Range of codes Examples Use 32-36 sp, !,", &num;, $ Used in denoting the type of event that has occurred (see below for examples) 48-127 0, 1, 2... ABC These are standard printable characters which are used to

etc denote numbers to the base 80 (see below) 37-47 As there are'holes'in the interpretation of the codes between 48 and 127, these 11 codes are used as substitutes for codes and characters that are not supported, e. g. ASCII 91 is changed to 37,123 to 43 etc.

Table 1 : Allocation of ASCII codes' For each event detected by the processor, data is added to the text message in the form of an event designator (one or two characters in the range 32-36), followed by the data field that goes with that event designator or type (a series of characters in the range 48-127, substituted with 37-47 where necessary). The content and length of the data field is dependent on the event type.

Rather than compress a file or message into 160 characters, the available character set is used to record individual data points in a compressed way, so that as many data points are compressed into one text message as possible. This is done by encoding the data into base 80 to fit within the printable character set between ASCII 48 and 127. Examples of base 80 encoding for numbers up to 512,000 (3 base characters) in Table 2 below :

Decimal 6400 80 1 ASCII ASCII ASCII 37, 840 5 73 0 5 Y 0 320, 000 50 0 0 b 0 0 23, 000 3 47 40 3 X 80 0 1 0 0 1 0 89 0 1 9 0 1 9 438 0 5 38 0 5 V 500, 000 78 10 0 '0 456 0 5 56 0 5 h Table 2: Examples of numbers encoded in Base 80

Event designator encoding The five characters between 32-36 are used to denote different types of event, for example " (ASCII 34) is used to denote that the ignition has been turned on, and &num; is used to denote that it has been turned off and $ is used to denote that 60 minutes have elapsed since the start of compilation of the SMS message. These characters can be combined in pairs to give a total potential of up to 20 event types (excluding the use of the space character). Table 3 below shows how some of these are used in vehicle monitoring:

Code Meaning Code Meaning Distance event-vehicle has One of the monitored sensors on travelled 8km since last event the vehicle has changed state s Ignition on $$ 60 minutes have elapsed since the start of the SMS message &num;Ignition off ! $ The GPS data solution has become valid Ignition has been off for 2 hours- ! ! Denotes the start of the closing prior to system shut down sequence and checksum for the message Moving average speed (over 30"Moving average heading (over 30 seconds) has changed by more than seconds) has changed by more than 40km/hr in 30 seconds 60 degrees in 30 seconds Table 3: Examples of code allocation In interpreting the code, the host facility knows that any character in the range 32-36 is to be interpreted as an event descriptor, and that the data characters following that code will be in accordance with the defined structure of that particular event message. It will also substitute back any characters in the ranges 91-96 and 123-127 prior to decoding the base 80 numbers in data.

Data Encoding The data accompanying each event type can be different, for example the distance covered since the last event does not need to be transmitted when the ignition is turned on, as the vehicle will not have moved since the ignition was turned off. An example of the coding used for the'ignition off event is given below for &num;xxxyyydd, where &num; is the event

descriptor character (see above), xxx is the base 80 code representing the longitude of the vehicle's current position, yyy is the base 80 code representing the latitude of the vehicle's current position, and dd is the base 80 code representing the distance in km covered by the vehicle since the ignition was switched on.

Other events may include the current direction or speed of the vehicle (although neither of these are appropriate to a stationery vehicle that has had its ignition turned off). xxx and yyy are derived as follows: Using 50 degrees North and 0 degrees East as the origin for all positions in Western Europe, the position of the vehicle is related to this origin in units of 0.0001 degrees. Using three digits of base 80 coding to this resolution gives a possible range of +/-25. 6 degrees from this origin-as shown below: For three digits in base 80, the maximum number that can be represented is: 79*6400 + 79*80 + 79 = 511,999 The minimum is of course zero (0,0, 0) and the median is 256000, hence the origin has been taken as 40,40, 40 and 40,40, 40 in base 80. In each case, to code this number in ASCII, the number has been put in the range of 48-127, so that it falls within the normal, printable character set (and outside those codes that have been reserved for event types and substitute characters).

This means that 40, 40, 40 (or 256,000 decimal) is represented as XXX-since the ASCII character for X is 88 (48 + 40).

Substitute characters are required for the range 91-96 and 123-127, as these are not transmitted over the networks as part of SMS messages. These are shifted as follows: 91 ( [) is translated into 37 (%)-as the square bracket sign is interpreted as an ordinary parenthesis-to aid display on a mobile.

96 (') is translated into 42 (*)-and so on. This is taken care of in the application at both ends of the transmission.

Distance travelled is represented as two characters. With a resolution of 1 km, this gives a \ maximum possible number of 6400km from two digits.

Bearing in degrees is represented in a single character. With a resolution of 5 degrees, this allows the range of 0 to 360 degrees to be covered by one digit.

Absolute time is represented by four digits, one for the month, one for the day of the month, one for the hour and one for minutes.

The SMS starts with a code number for the vehicle and a sequence number for the message, and concludes with a checksum which is placed in the printable character range.

Although these are specific examples of the use of this coding for vehicle monitoring, it could also be used for other monitoring applications using SMS messaging.

Figure 4 shows an example of the first 40 bytes of a message 120. The first 10 bytes, or identification segment 122 contains a vehicle identifier 124, the date and time and the ignition status. The subsequent 10 byte segments 126,130, 132 relate to specific events which have occurred to the vehicle 12, with each segment having an event identifier and then event information relating to the longitude, latitude so as to denote the absolute position of the vehicle, the time since the start of the message, the speed and the bearing of the vehicle. The event segments 126,130, 132 are stored in succession for different types of events, until a text message is completed, see Figure 5, at which point the message is closed off with a closing segment including a closing message 134 and a checksum 136. The message is then ready for transmission over the GSM/PSTN network 10 to the host facility 14.

Claims

C660. 00/W CLAIMS

1. A method of monitoring a movable body, comprising detecting a first event associated with the body and acquiring first event data relating to the first event, compressing the first event data, placing the first event data in a first segment of a text message, placing event data relating to subsequent events in successive segments, and transmitting the text message to a host facility.

2. A method of monitoring a movable body according to Claim 1, further comprising converting the first event data and subsequent event data into Base 80, thereby to achieve data compression.

3. A method according to Claim I or Claim 2, further comprising placing a first code describing the first event at the beginning of the first segment, and placing subsequent codes at the beginmng of successive segments to describe subsequent events.

4. A method according to any of the preceding claims, further comprising checking time elapsed after movement of the body has ceased, and stimulating transmission of a text message once the body has been stationery for a set period of time.

5. Position monitoring apparatus comprising a data acquisition device, data compressing means, and transceiver means for communicating with a host facility.

6. Position monitoring apparatus in accordance with Claim 5, further comprising means for placing the data acquisition device in a quiescent mode.

7. Position monitoring apparatus in accordance with any of the preceding claims, wherein inputs to the data acquisition device are fed through opto-isolation circuitry before reaching the data acquisition device.

8. A system for monitoring a movable body, comprising a host facility, position monitoring apparatus comprising a data acquisition device, data compressing means and transceiver means for communicating with the host facility, wherein the host facility communicates with the position monitoring apparatus using text messages.

9. A method of monitoring a movable body substantially as herein described with reference to the accompanying drawings.

10. Position monitoring apparatus substantially as herein described with reference to the accompanying drawings.

II. A system for monitoring a movable body substantially as herein described with reference to the accompanying drawings.