GB2424483A

GB2424483A - Recording and collecting data and sensor device for use therein

Info

Publication number: GB2424483A
Application number: GB0505676A
Authority: GB
Inventors: Yona Newman; Benjamin Baraz
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2005-03-22
Filing date: 2005-03-22
Publication date: 2006-09-27
Anticipated expiration: 2025-03-22
Also published as: GB2424483B; GB0505676D0

Abstract

A system (100) for recording and collecting data comprises a plurality of sensor devices (101-105) each sensor device (102) being operable to measure and record a value of a physical parameter, such as local environmental temperature, and each being operable to receive an input signal (108) and to provide an output signal (109) comprising data related to the recorded value. The sensor devices are operable to deliver signals comprising data (N1-N12) around a closed loop of the sensor devices wherein the output signal from each sensor device (102) is delivered as an input signal (109) to a neighbour sensor device (104) in the loop, each of the sensor devices being operable to combine the data it has recorded to data received in a received signal and to include the combined data in the output signal it provides.

Description

TITLE: SYSTEM AND METHOD FOR RECORDING AND COLLECTING

DATA AND SENSOR DEVICE FOR USE THEREIN

FIELD OF THE INVENTION

The present invention relates to a system and a method for recording and collecting data and a sensor device for use therein. In particular, the system includes a plurality of smart sensor devices employed to record values of a physical parameter such as temperature.

BACKGROUND OF THE INVENTION

Smart sensor devices, e.g. devices which include RF ID tags, are finding increasing use in applications for tracking, locating and monitoring various kinds of goods such as parcels, containers, trucks, boxes, livestock and so on. Such sensor devices are able to record and process information and to report it, when requested, to an interrogation device. Smart' indicates that a sensor device has some inherent intelligence, e.g. as provided by a computing device such as a digital signal microprocessor, and an ability to communicate, e.g. by a transceiver such as a RF transceiver.

In addition, smart sensor devices can also measure, store and report on environmental physical parameters over time. Such parameters may include temperature, air pressure, altitude, relative humidity, shock, vibration and so on. The ability of the sensor device to store values of such parameters, along with time stamps, together with data relating to goods monitored in the measured environment, enables suppliers, purchasers and handlers of the goods to track and verify that the goods have not been subjected to out-of-limit conditions or stresses during storage or transportation in the measured environment.

The sensor devices can be interrogated in various known ways to extract the data they have gathered. For example, hand-held mobile RF data terminals or fixed RF terminals, e.g. at the entrance to a building, can be employed to interrogate such smart sensor devices and then either to carry out local processing of the data received from the interrogation or to transfer the data to a remote location, e.g. fixed central control station, for analysis and exception reporting.

Smart sensor devices need to operate for long periods. Various mechanisms have been devised to minimize power consumption in such devices, both during normal operation and during interrogation to collect data. These mechanisms include power management systems with long sleep times between measurements, and very low power transmission protocols.

The purpose of the present invention is to provide an improved system, method and smart sensor device for use in recording and collection of data.

SUMMARY OF THE INVENTION

According to the present invention in a first aspect there is provided a system for recording and collecting data, the system being as defined in claim 1 of the accompanying claims.

According to the present invention in a second aspect there is provided a method of recording and collecting data, the method being as defined in claim 21 of the accompanying claims.

According to the present invention in a third aspect there is provided a smart sensor device as defined in claim 22 of the accompanying claims.

The present invention provides a system of sensor devices, a method of operating the system and a sensor device included in the system. The system and method operate to provide beneficially a new efficient procedure for collection of data recorded by sensor devices of the system. This new procedure may be applied with minimal power consumption to the collection of data from any number of sensor devices relating to any number of physical parameters measured by the sensor devices.

Further benefits will become apparent from the following

description.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block schematic diagram of a sensor system.

FIG. 2 is a block schematic diagram of a smart sensor device included in the system of FIG. 1.

DESCRIPTION OF E.ffiODIMENTS OF THE INVENTION

FIG. 1 is a block schematic diagram of a sensor system 100. The system 100 includes five smart sensor devices, namely a sensor device 101, a sensor device 102, a sensor device 103, a sensor device 104 and a sensor device 105. The system 100 also includes an external interrogation device 106. Each of the sensor devices 101 to 105 measures the environmental temperature in its own location and records the value.

Each of the sensors 101 to 105 and the external interrogation device 106 includes a RF transceiver allowing the device to communicate by radio, e. g. using a known RF communication procedure.

At a given time, which may be a predefined period after a previous collection of data, the external interrogation device 106 begins a data collection procedure. The device 106 issues an RF interrogation signal 107 which is received by the nearest sensor device, i.e. sensor device 103. In the event that more than one sensor device receives the interrogation signal 107, a procedure can be run which allows the sensor devices 101-105 and/or the interrogation device 106 to determine which is the nearest sensor device to the device, namely the interrogation device 106, issuing a received signal. For example, the sensor devices 101-105 may negotiate between themselves and/or the with the interrogation device 106 using any of the known methods for selection, such as use of Received Signal Strength Indication (RS5I) or collision detection and re-tries with random delay.

The signal 107 instructs that the most recent value of temperature recorded by each sensor device in the system 100 is to be collected. In response, sensor device 103 retrieves the latest temperature data from its memory and, in a manner to be described later, issues an RF signal 108 including this data. This is sent to and received by the next nearest sensor device 102. Sensor device 102 retrieves the latest temperature data from its memory and, in a manner to be described later, issues an RF signal 109 including the temperature data recorded by sensor device 102 as well as the temperature data recorded by sensor device 103. This is sent to and received by the next nearest sensor device 104. Sensor device 104 retrieves the latest temperature data from its memory and, in a manner to be described later, issues an RF signal 110. This includes the temperature data recorded by sensor device 104 as well as that recorded by sensor devices 103 and 102. The signal 110 is sent to and received by the next nearest sensor device 101. Sensor device 101 retrieves the latest temperature data from its memory and, in a manner to be described later, issues an RF signal 111. This includes the temperature data recorded by sensor device 101 as well as that recorded by sensor devices 103, 102 and 104. The signal 111 is sent to and received by the next nearest sensor device 105. Sensor device 105 retrieves the current temperature data from its memory and, in a manner to be described later, issues an RF signal 112. This includes the temperature data recorded by sensor device 105 as well as that recorded by sensor devices 103, 102, 104 and 101. The signal 112 is sent to and received by the next nearest sensor device 103, thereby completing one round trip of data collection from the sensor devices 101 to 105.

A preferred procedure for collecting the temperature data in the system 100 shown in FIG. 1 is as follows. Each of the sensor devices 101 to 105 when receiving an appropriate signal, i.e. one of the signals 107 to 111, calculates a running mean value of the temperatures recorded by the devices which have been interrogated so far, including the device undertaking the current calculation. Each of the sensor devices also calculates a (positive or negative) deviation of the temperature it has recorded from that calculated mean and also re-calculates for previously interrogated sensor devices whose data it has received in the incoming signal a deviation of the temperature for each of those devices from that re-calculated mean.

Assume that the sensors 101 to 105 have temperature recordals in accordance with Table 1 as follows when a data collection procedure is being undertaken. 7 C

Table 1

Sensor device Temperature (degrees C) Difference from mean temperature (degrees C) 101 40 -8 102 35 -13 103 50 2 104 60 12 55 7 The mean temperature recorded is 48 degrees C. The value of the difference of the temperature recorded by each of sensor devices 101 to 105 from the mean 48C is as shown in the third column of Table 1. These values will be referred to again later.

When the first sensor device in the system 100, namely sensor device 103, receives a signal, namely signal 107 indicating that the sensor 103 should begin data collection, the procedure operates as follows.

Sensor 103 initially has the temperature value recorded by itself, i.e. 50, but no further data from other sensor devices. The sensor 103 calculates a mean temperature value of 50 and a difference of 0 from the mean. The signal 108 issued by the sensor device 103 therefore includes this data. The data may be included as a string of four numbers which represent respectively: (1) the parameter recorded; (ii) the mean of the parameter recorded; (iii) the identity of the sensor device; and (iv) the difference of the value of the parameter recorded by that sensor device from the mean value for that parameter.

For example, the latest temperature recorded may be parameter 1' . The identity of sensor device 103 may be 3' . Thus, the data issued by sensor device 103 in signal 108 may be included in a data string as follows 1, 50, 3, 0. Sensor device 102 upon receiving signal 108 calculates from this received data and that which it has most recently stored itself (35C) that the running mean temperature is 42.5. The sensor device 102 also calculates the differences from the mean of the temperature recorded by sensor device 103 and sensor device 102 to be 7.5 and -7.5 respectively. The data is passed on by inclusion in the signal 109. The data may be in the form of a six number string wherein the six numbers in order are as follows: (i) the parameter recorded; (ii) the mean of the parameter recorded; (iii) the identity of the first sensor device (device 103) whose data has been collected; and (iv) the difference of the value of the parameter recorded by the first sensor device (103) from the mean value for that parameter.

(v) the identity of the second sensor device (102) whose data has been collected; and (vi) the difference of the value of the parameter recorded by the second sensor device (102) from the mean value for that parameter.

Suppose that sensor device 102 has an identity 2' . The six number data string included in the signal 109 may therefore be 1, 42.5, 3, 7.5, 2, -7. 5.

This procedure continues with data being calculated and inserted into a new data string at each sensor device and handed on from sensor device to sensor device in a clockwise ioop as shown in FIG. 1. When a sensor device sees its own identity in the received data string or stream it may hand it on without change.

The procedure may be continued until a pre- determined number of round trips around the loop of sensor devices beginning and ending at sensor device 103 have taken place. When the sensor device 103 detects that such a number of round trips have been completed, or alternatively detects that the data has not changed from one or more previous round trips, it issues the RF signal 112. This is sent to and received by the external interrogation device 106. The external interrogation device 106 may issue a RF signal which is sent to and received by a remote terminal (not shown), e.g. at a product control centre which collects data from a plurality of sensor systems similar to the system 100 in different geographical regions.

The final RF signal 112, including the data collected from all sensor devices 101 to 105, may include a data string or stream which includes the following sequence of numbers: Ni, N2, N3, N4, N5, N6, N7, NB, N9, Ni0, Nil, and Ni2 as follows: (i) Ni is the parameter recorded; (ii) N2 is the mean of the parameter recorded; (iii) N3 is the identity of the first sensor device (device 103) whose data has been collected; (iv) N4 is the difference of the value of the parameter recorded by the first sensor device (103) from the mean value for that parameter.

(v) N5 is the identity of the second sensor device (102) whose data has been collected; (vi) N6 is the difference of the value of the parameter recorded by the second sensor device (102) from the mean value for that parameter; (vii) N7 is the identity of the third second sensor device (104) whose data has been collected; and (viii) N8 is the difference of the value of the parameter recorded by the third sensor device (104) from the mean value for that parameter.

(ix) N9 is the identity of the fourth sensor device (101) whose data has been collected; and (x) Nb is the difference of the value of the parameter recorded by the fourth sensor device (104) from the mean value for that parameter; (xi) Nil is the identity of the fifth sensor device (105) whose data has been collected; and (xii) N12 is the difference of the value of the parameter recorded by the second sensor device (105) from the mean value for that parameter.

Suppose that the identity numbers for the sensor devices 101 to 105 are respectively 1' to 5' Referring again to the third column of Table 1, the data string Ni to N12 therefore consists of the following data values 1, 48, 3, 2, 2,-13, 4, 12, 1 -8, 5, 7. The external interrogation device 106 may add a time stamp to the data string when it receives the signal 113 before storing and/or sending the data to a remote terminal.

In another embodiment of the invention, a procedure for collecting data described with reference to FIG. 1 may be initiated without the involvement of the external interrogation device 106. Thus, one of the sensor devices 101 to 105, e.g. the device 103, may initiate the data collection procedure, e.g. when it detects that a pre-determined period of time has passed since a previous data collection. When the sensor device which initiates the procedure detects that data from all of the sensor devices is ready to be forwarded, it may then send the data in a signal to a remote terminal, e.g. at a product control centre.

In the embodiments of the invention described above the data string or stream received by any one of the sensor devices may be stored in a memory of the device as well as being processed in a signal processor of the device. Alternatively, the data string may be stored in memory in only a sub-set of the devices or in only one device, e.g. the first one to start the data string (and last one to receive the data string from other devices) Data related to one or more other parameters may be recorded and collected in a manner similar to that which has been described for temperature. For example, data relating to relative humidity or one of the other parameters mentioned above may be recorded and collected. The data relating to the further parameter(s) may be collected in one or more separate collection procedures but preferably data relating to all recorded parameters is collected at the same time in a single procedure.

Thus, for example, relative humidity may be designated as parameter 2'. The relative humidity data for the sensor devices may be included in the data string after all the temperature data has been included as described above with reference to the data string including values Ni to N12. Alternatively, the data for each of the recorded parameters may be collected and included as a set for each sensor device in turn. In any case, it is preferred that for each recorded parameter a running mean value and a deviation or difference from the mean value is calculated by each sensor device in turn as described earlier with reference to the collection of temperature data.

One (or more) of the sensor devices may not record all parameters. In that case, it may leave the received mean value for the unrecorded parameter(s) unchanged and add a zero for the difference value for the unrecorded parameter(s). Alternatively, a marker value may be inserted into the data string to indicate an absence of that value for that sensor device.

Where a data string in a data collection procedure reaches a sensor device which is not the first in the collection loop, e.g. sensor device 104 in the system shown in FIG. 1, the sensor device may be the first one to provide data for a particular parameter. In that case, the sensor device may use its own data to start the collection for that parameter in the same way that the sensor device 103 started the procedure for collection of temperature data as described earlier with reference to FIG. 1. The value for the new parameter of that sensor device becomes the first running mean for the new parameter.

Each of the sensor devices may be programmed to recognise a parameter value it has recorded as an off scale' value. For example, the value recorded by a sensor device may be very different from the running mean by an amount greater than a threshold amount or more than X times the running mean, where X is a predetermined multiplier, or outside a predetermined range of values. The off scale' value may be indicated in the data string by a flag set of numbers in the data string or a reserved code value for the relevant parameter which signifies an off scale' value.

Where the external interrogation device 106 detects a flag set or reserved value in a data string to indicate an off scale value for a particular value by one (or more) of the sensor devices, the device 106 may issue a signal which is passed around the loop until it arrives at the sensor device which produced the off- scale value. This signal causes the relevant sensor device(s) that produced the off scale value or all sensor devices to produce an immediate readout for the relevant parameter or all parameters. The readout may include not only data recorded and output in a previous collection procedure, but also data recorded at intermediate times between previous collections.

If a particular parameter scale is not suitable, for example temperature in positive degrees Celsius, and there is an expected range of recorded values which are off scale', e.g. in a range from say -30C to +50C, then an arbitrary shifted scale of 0 to 100 may be used where 0 on the arbitrary scale is equivalent to -40C and 100 on the arbitrary scale is equivalent +60C.

One or more of the sensor devices, e.g. the sensor device 103 or all of the sensor devices 101 to 105, may be programmed to shift the normal scale dynamically in this way to allow for the parameter readings, whilst passing on the shifted scale definition to the next sensor devices in the loop, as well as correcting the current running mean and difference values to suit the new scale.

Where the number of sensor devices included in a system is large, the system may be sub-divided into groups or sub-nets of sensor devices. This sub-division may be executed dynamically when it has been detected that the number of sensor devices in a given set has exceeded a pre-determined threshold number of devices, e.g. when one or more devices has been added to the system. Each of the sub-nets formed may collect and concatenate data from the sensor devices in the sub-net in one of the ways described earlier. The collected data may be delivered to one or more other such sub-nets or may be separately transferred outside the system, e.g. via an external interrogation device.

FIG. 2 is a schematic block diagram showing the main components of the sensor device 102. This may be considered to be illustrative of all of the sensor devices in the set of sensor devices 101-105 shown in the system 100 in FIG. 1. The sensor device 102 includes sensors 201, 202 and 203 which measure values of three different parameters. Each of the sensors 201, 202 and 203 is connected to a memory 204 which records and stores current values of the parameters measured by the sensors 201, 202 and 203. The recording and storing may be carried out periodically, according to a pre- determined time parameter, or in a manner which is not time based but event driven, e.g. when a parameter being measured changes by more than a pre-determined threshold change value. The memory 204 may also store other data and software programs needed in operation of the sensor device 102. A timer 207 operates in conjunction with the memory 204 to time stamp when values from the sensors 201, 202 and 203 are recorded. A processor 205 controls intelligent operations and makes calculations for the sensor device 102.

An input signal 108 (referred to earlier with reference to FIG. 1) is received as an RF signal by a transceiver 206. An output signal 109 (referred to earlier with reference to FIG. 1) is sent as an RF signal by the transceiver 206. The transceiver 206 is connected to the processor 205 and delivers the data string or stream included in the input signal 108 to the processor 205. The processor 205 is connected to the memory 204 and stores the data of the data string in the memory 204. The processor 205 also extracts the most recently stored values of the parameters from the memory 204. The processor 205 re-calculates a running mean and a difference from the mean for each parameter value it possesses (including values received for other sensor devices in the data string included in the input signal 108) . The processor 205 includes these values in an enlarged data string and passes the enlarged data string to the transceiver 206. The transceiver 206 sends the output signal 109 including the enlarged data string.

The embodiments of the invention described earlier autonomously and dynamically allow an unspecified number of sensor devices and parameters to be used in the building of a data transmission stream.

The concatenated data transmission stream produced, where large, may be optimally compressed by the procedures which have been described.

The data collection procedures described also allow for minimal power consumption of sensor devices when transferring the data since each sensor device only needs to communicate with its immediate neighbour.

The collection procedures embodying the invention allow any sensor device to be interrogated by the device initiating the interrogation, e.g. the interrogation device 106 in FIG. 1, in order to receive all of the relevant data the sensor device has measured and stored.

Claims

1. A system for recording and collecting data including a plurality of sensor devices each operable to measure and record a value of a physical parameter and each operable to receive an input signal and to provide an output signal including data related to the recorded value, wherein the sensor devices are operable to deliver signals including data around a closed loop of the sensor devices wherein the output signal from each sensor device is delivered as an input signal to a neighbour sensor device in the loop, each of the sensor devices being operable to combine the data it has recorded with data received in a received signal and to include the combined data in the output signal it provides.

2. A system according to claim 1 wherein each of the sensor devices is operable to provide an output signal in which the data is included in a concatenated stream of data.

3. A system according to claim 1 or claim 2 wherein each of the sensor devices is operable to add to the data it has included in the output signal an identifier code to identify the sensor device which added the data.

4. A system according to any one of the preceding claims wherein each of the sensor devices is operable to calculate a running mean of the values of the recorded physical parameter from (i) data, if any, received in an 19 - input signal relating to values recorded by one or more other sensor devices; and (ii) a value it has recorded.

5. A system according to claim 4 wherein each of the sensor devices is operable to calculate for each value of the physical parameter it possesses a difference from the running mean and to include the difference value or values in the data of its output signal.

6. A system according to any one of the preceding claims wherein at least one of the sensor devices is operable to measure and record values of a plurality of physical parameters and to provide output signals including values relating to the parameters.

7. A system according to claim 6 wherein the said at least one sensor device is operable to produce an output signal which includes data relating to the plurality of parameters.

8. A system according to claim 6 or claim 7 wherein the said at least one sensor device is operable to include in the data it includes in the output signal an identifier code for each parameter for which it has included data.

9. A system according to any one of claims 6 to 8 wherein each of the sensor devices is operable to provide, in an output signal, data relating to all of the parameters recorded by any of the sensor devices in the loop.

10. A system according to any one of claims 6 to 9 wherein at least one of the sensor devices is operable to include in data of its output signal an indicator code indicating that that sensor device has no data relating to one or more given parameters.

11. A system according to any one of the preceding claims wherein at least one of the sensor devices is operable to include in data of its output signal an indicator code indicating that a value of a parameter recorded by that sensor device is off scale.

12. A system according to any one of the preceding claims including an interrogation device operable to initiate a collection of data from the sensor devices.

13. A system according to claim 12 wherein the interrogation device is external to the plurality of sensor devices and is operable to issue a signal to one of the sensor devices to begin the collection.

14. A system according to claim 12 wherein the interrogation device is also one of the sensor devices.

15. A system according to any one of claims 12 to 14 wherein the interrogation device is also operable to receive a signal including collected data and to forward the collected data to a remote terminal.

16. A system according to any one of the preceding claims including at least one scale re-set device which is operable to re-set a scale of values relating to one or more of the measured parameters and to send a message to each of the sensor devices to indicate the reset scale.

17. A system according to claim 16 wherein at least one re-set device is also one of the sensor devices.

18. A system according to any one of the preceding claims including a plurality of sub-nets of sensor devices wherein each sub-net of devices is operable to communicate in a closed loop and to collect data from the sensor devices in its sub-net.

19. A system according to claim 18 wherein at least one of the sub-nets is operable to deliver collected data to at least one other sub-nets or to a device dedicated to collecting data from all of the sub-nets.

20. A system according to any one of the preceding claims wherein the sensor devices are operable to receive the input signals and to send the output signals by radio communication.

21. A method for recording and collecting data including measuring and recording the value of a physical parameter by a plurality of sensor devices, receiving by each of a plurality of the sensor devices an input signal and sending by each of the plurality of the sensor devices an output signal, the input signal and the output signal including data related to recorded values of the physical parameter, wherein signals including data are delivered around a closed loop of the sensor devices and wherein the output signal from each sensor device is delivered as an input signal to a neighbour sensor device in the loop and each sensor device combines the data it has recorded with data received in a received signal and includes the combined data in its output signal.

22. A smart sensor device operable as one of the sensor devices in the system according to any one of the preceding claims 1 to 20.