WO2013114139A1

WO2013114139A1 - Moveable object detection

Info

Publication number: WO2013114139A1
Application number: PCT/GB2013/050244
Authority: WO
Original assignee: DETEQ SOLUTIONS Ltd
Current assignee: DETEQ SOLUTIONS Ltd
Priority date: 2012-02-01
Filing date: 2013-02-01
Publication date: 2013-08-08
Anticipated expiration: 2014-08-01
Also published as: GB201415402D0; GB2514067A; GB201201764D0

Description

MOVEABLE OBJECT DETECTION

Field of the Disclosure The disclosure relates to moveable object detection. A device for detecting a moveable object, as well as a system incorporating one or more such devices and corres ponding methods of moveable object detection are provided. The disclosure is particularly, but not exclusively, applicable to monitoring vehicles parking in a parking area.

Background to the Disclosure

There is currently no system available that will allow car park owners and councils (or other bodies administering on-street parking) to determine precisely if a car parking space is available, if it is being used and exactly who is parked (and with what permissions). Currently Civil Enforcement Officers (CEOs) are needed to patrol streets to determine whether a vehicle has created an offence and then subsequently to issue a ticket.

A similar problem applies to the driver of a vehicle, who has no information about where available parking spaces may be.

The disclosure answers these problems.

Summary of the Disclosure Aspects of the disclosure are set out in the claims.

Preferred embodiments of the disclosure are described with reference to the accompanying drawings, by way of example only.

Brief Description of the Drawings

Figure 1 is a schematic illustration of a system for monitoring vehicles in a parking area.

Figure 2 is a schematic illustration of an antenna of a device for detecting a vehicle.

Figure 3 is a schematic illustration of the device for detecting a vehicle, incorporating the antenna. Figure 4 is a schematic illustration of a radiation pattern of the antenna.

Figure 5 is another schematic illustration of the device for detecting a vehicle, showing the exterior of the device.

Figure 6 is a schematic illustration of a lid of the device for detecting a vehicle. Figure 7 is a cross-sectional view of the device for detecting a vehicle.

Figure 8 is a schematic illustration of an antenna of a device for detecting a vehicle, according to an alternative embodiment.

Figure 9 is a block diagram illustrating functional components of the device for detecting a vehicle.

Figure 10 is a graphical illustration of signal strength over time during a test of a version of the device for detecting a vehicle.

Figure 1 1 is a graphical illustration of signal strength over time during a test of a another version of the device for detecting a vehicle. Detailed Description of the Preferred Embodiments

Referring to Figure 1 , there is provided a system 100 for monitoring vehicles 102 parking in a parking area, such as a street, neighbourhood, town or other geographical area. The system 100 comprises one or more devices 104 for detecting the vehicles 102. The vehicles 102 carry Radio-Frequency Identification RFID tags (not shown). An RFID reader 108 is located in the parking area for reading information carried on the RFID tags. The RFID reader 108 and the devices 104 communicate with a base station 106, which in turn communicates with a data centre 110.

As shown in Figures 2 to 7, the devices 104 for detecting vehicles 102 each comprise a box with an antenna 200 on its lid 600. In this embodiment, the antenna 200 has two elements 202, each being spirals in the plane of the lid 600, rotated 180° with respect to one another. This arrangement means that the antenna 200 has a radiation pattern in the form of a dipole, as shown in Figure 4, with the lobes extending normal to the plane of the lid 600. This means that the antenna 200 has high gain for signals propagating perpendicular to the plane of the lid 600, but low gain for signals propagating in a direction parallel to the plane of the lid 600 or thereabouts. If the plane of the lid 600 is parallel to a road surface, e.g. because the device 104 is positioned under the road surface, this means that the antenna 200 is sensitive to signals coming from above the road, but not to those coming from directions near the horizon.

An antenna 800 according to another embodiment is illustrated in Figure 8. This antenna 800 is interchangeable with the antenna 200 of the first embodiment. It comprises first and second conductive elements 802, 804 that are concentric with one another. The first conductive element 802 comprises an arc extending through 180° and the second conductive element 804 is ring-shaped and encloses the first conductive element 802. Like the antenna 200 of the first embodiment, the antenna 800 illustrated in Figure 8 has a radiation pattern in the form of a dipole, as shown in Figure 4, with the lobes extending normal to the plane of the lid 600.

The device 104 has a detector 304 coupled to the antenna 200, as well as an indicator 300 coupled to the detector 304, and a battery 302. These elements are housed in a waterproof box. In this embodiment, the detector 304 is mounted on a Printed Circuit Board (PCB) 602 on the inside of the lid 600. A transmitter 700 is also provided for communicating with the base station 106.

The system 100 can use Global Positioning System (GPS) transmissions, but in the preferred embodiment, the system 100 uses terrestrial Global System for Mobile communications (GSM) signals. In other embodiments, virtually any electromagnetic wave that is attenuated by a vehicle 102, particularly a radio signal, can be used.

The major features of the system 100 are:

• Unambiguous indication of the presence of an object, such as a vehicle 102, using attenuation of available radio waves.

• The device 104 takes readily available/third party

transmitted/terrestrial/non-terrestrial/naturally available/occurring radio signals and uses attenuation/dielectric loss as a method for detecting vehicles 102.

• Very low power requirement for long periods of operation, e.g. years, without maintenance.

· The ability to determine exactly when a vehicle 102 arrives at a parking space.

• The device 104 is placed on the road in the centre of each parking space and it registers a vehicle 102 as soon as it stops over the antenna 200.

• Radio networking between road mounted devices 104 and the base station 106.

• A data centre 110 for analysing data.

• Pulsed (intermittent) operation of the device 104 to optimise battery

consumption.

• An independent, but in all other respects identical sensor (not shown), to indicate local (region of interest) signal strength and provide a differential reference to eliminate local variations in carrier/signal strength. • Rejecting the relatively intermittent nature of passing spurious hand held mobile phones at a similar frequency to a carrier wave received from a base station.

• The mechanism is calibrated dielectric loss that occurs when a large metal object obscures the antenna 200.

• The devices 104 are all wireless and connected to each other in a grid pattern that uses low power Wi-fi connectivity to pass the information back to a single uplink which connects to a server and software of the data centre 110.

Systems have been proposed in the past that use magnetic sensors. An advantage in using radio waves is that polymer composites are increasingly used in vehicles 102. These materials are not magnetic, but they still dielectrically attenuate radio signals. The system 100 of the present disclosure is independent of spurious signals from ferrous objects.

In the preferred embodiment, the devices 104 communicate with the base station

106 wirelessly. There are a number of different radio signal systems available for communicating between the devices 104, which are road mounted, and the base station (or host data collection/processing location), such as WiFi, Zigbee etc. Multiple base stations 106 in a network can allow long range communications whilst allowing the devices 104 to be fairly low power.

At its simplest, the device 104 detects instantly whether a signal being received by a detector 304 has been covered by a vehicle 102. The "always on" nature of the device 104 and the instant response make the device 104 unique not only for this application but also in a number of other applications.

The system 100 does not require positional information, as this is provided via a

RFID network given a known position of just one or two of the devices 104. Initially, the device 104 is able to record highly accurate data on:

• Time of arrival

• Duration

· Time of leaving

The system 100 is designed to be modular, which allows other devices 104 to be added as needed. This, combined with the ultra low power requirements of the devices 14, gives immense flexibility in use and deployment.

Sensors designed specifically to detect and monitor air quality are also included in the system 100. In some embodiments, environmental sensors can be added to any of the devices 104 in the system 100, such as for detecting CO, C0₂, N0₂, S0₂, other petrol emissions and particulate counters for diesel emissions. Further types of sensor can also be added, as required.

The system 100 also includes writeable active RFID tags as "permits", which are read remotely by RFID readers 108. The active tags are programmable with data at the time they are issued, allowing different classes of permit to be issued (residents' permit, doctors' permit, visitors' permit, etc). Moreover, restrictions within each class can be programmed. For example, a visitor may be restricted to parking at specific times in a parking zone.

The RFID readers 108 have a range of between 200 and 400 metres and are capable of handling megabits of data, which is far in excess of the information flow rates that are usually needed. The long range of the RFID readers means relatively few need to be deployed per street. This reduces costs.

All the component parts of the system 100 (devices 104, RFID tags, RFID readers 108, etc.) are connected to a wireless mesh network which captures data from the devices 104 and transmits it to the data centre 1 10 where it is processed and analysed. The Mesh network is highly resilient as it is in effect self-repairing. The nature of a mesh network means that if any single part fails connections are re-routed to the next "node" rather than lost. This gives the system 100 an exceptionally high level of resilience.

• The data centre 1 10 can provide data sets including:

• Type of permit issued

^■ Resident Permit

^■ Disabled Badge

^■ Pay & Display Season

^■ Ticket

^■ Any other variation

• Vehicles' entitlement to be parked in a particular space

• Time of vehicle arrival

• Length of time parked

• Time of departure

• Parking over-stays

This and other data generated by the system 100 is analysed within the date centre 110 and packaged for use by drivers and Civil Enforcement Officers (CEOs) in-car, and by councils and/or car park owners.

The Environmental data set can include:

• Carbon Dioxide

• Carbon Monoxide • Sulphur Dioxide

• Particulates (Diesel)

• Nitrogen Dioxide

• Ozone

· Heat

• Humidity

Using analytical tools, Local Authorities and their parking contractors can monitor the level of pollutants at street level and in real time in any City, town or village where the system 100 is deployed.

A smart phone application ("App") can enable users to locate parking spaces within their vicinity. This App has two formats. One as a quick statement of parking available in a street found by a search function. The second is an overlay on a local map showing spaces available in an area.

The system 100 is able to determine if a car parking space is empty, exactly when a vehicle enters the space, the duration of the stay and when it leaves. This is combined with precise information about what permissions a vehicle 102 has for that space. With this information it is possible to automate the process of "ticketing" any vehicle 102 that creates a parking offence.

The same information can be made available to drivers via the smart-phone "App" that shows full details of spaces available in their vicinity.

Referring to Figure 9, the detector 304 comprises a band pass filter 902, a Low Noise Amplifier (LNA) 904, an Analogue to Digital Converter (ADC) 906, a detection stage 908 and a power controller 910.

The band pass filter 904 is arranged to filter the radio signals received at the antenna 200, 800, to attenuate components of the received signal that are higher and lower in frequency than a wanted component of the received signal. In the preferred embodiment, the wanted component of the received signal is the downlink of a mobile telecommunications network.

In most mobile telecommunications networks, the downlink, that is communication signals transmitted from the network infrastructure to the mobile devices, is at a different frequency to the uplink, that is communication signals transmitted from the mobile devices to the network infrastructure. For the purposes of the present system 100, it is useful to try to isolate the downlink from the uplink, as the downlink tends to have more constant signal strength at any one geographical location than the uplink, which increases in strength when a mobile device is nearby. By way of example, a typical GSM system has a downlink in a first frequency band between 935 MHz and 960 MHz and an uplink in a second frequency band between 890 MHz and 915 MHz. So, having the band pass filter 904 attenuate radio signals outside of the first frequency band can be effective.

The LNA 904 amplifies the signal output by the band pass filter 902. As the radio signals are liable to be received at the antenna 200, 800 with a large range of different signal strengths, the LNA 904 amplifies the signal output by the band pass filter logarithmically. This has the effect of amplifying lower strength signals be a greater amount than higher strength signals, and thereby outputting an amplified signal that has a smaller dynamic range than a signal that would be generated by liner amplification. In other embodiments, rather than using logarithmic amplification, Automatic Gain Control may be employed. The amplified signal output by the LNA 904 is then converted to a digital signal by the ADC 906. Specifically, the amplified signal output by the LNA is an oscillating signal having an envelope of variable amplitude and this is converted by the ADC 906 to a Direct Current (DC) level having a size proportional to that amplitude.

The detection stage 908 detects the DC level and transmits an indication of the strength of the radio signal being received at the antenna 200, 800 to the base station 106. In this embodiment, the detection stage 908 scales the DC level to generate the indication. Specifically, the detection stage applies antilogarithmic scaling to the DC level, so that the indication corresponds more linearly to the actual strength of the radio signal received at the antenna 200, 800, rather than the signal output by the LNA 904.

In order to reduce power consumption, the power controller 910 only supplies electrical power to the LNA 904, ADC 906 and detection stage 908 when they are in operation. The detector 304 only needs to transmit the signal strength indication to the base station intermittently for the arrival and departure of a vehicle to be detected. For example, the indication may be transmitted one every second. On the other hand, the LNA 904, ADC 906 and detection stage 908 can be turned from standby to operational, settle, and generate an accurate indication within a few milliseconds. This allows the LNA 904, ADC 906 and detection stage 908 to be in standby mode for as much as 99% of the time, greatly reducing power consumption.

Referring to Figure 10, a version of the system 100 using GPS signals has been tested and graph of how the detected GPS signal varies with time as a vehicle 102 is moved over or away from the device 104 is shown.

In the version of the system 100 that was tested, the antenna 200, 800 comprised two magnetic base car external GPS powered aerials. The detector 104 included customised DC748A Linear™ LT5534 60dB RSI Logarithmic amplifiers/3 dB down at 0.25HzX10 linear amplifiers. During periods of high environmental temperature > 25 deg C it was noticed that the 'zero' (antenna covered) signal was drifting upwards and in some cases exceeded the 2.5 maximum permitted by a data logger/Picolog USB 10 bit of the device 304. Thermal drift was confirmed by monitoring amplifier temperature when cooling with ice to well below ambient. A significant reduction in offset drift was achieved by cooling.

Plot 1002 shows variation in signal strength when no vehicle 102 is detected. Plot

1000 shows attenuation of the signal during a first period, when a vehicle 102 is present over the antenna 200, 800, followed by a period of no attenuation when no vehicle 102 is present, and finally another period of attenuation when the vehicle 102 returns. The results suggest that the principal criterion of useable discrimination between signal and noise is practical and that by cyclically sampling a sufficiently low power system could be achieved for remote road - mounted battery operation.

In Figure 1 1 , a comparison is made between an indicator generated based on a linear correspondence with the DC level generated after logarithmic amplification by the LNA 904, and an indicator generated based on an antilogarithmic correspondence with the DC level generated after logarithmic amplification by the LNA 904. In the graph, plot 1100 is the linear indication and plot 1 102 is the antilogarithmic indication. It can be seen that the ratio of amplitudes of the indicator when a vehicle 102 is present and when a vehicle 102 is not present averages 5.0 to 1 , and is 4.7 to 1 in the worst case, for the linear indicator (see levels A and B), but that the ratio of amplitudes of the indicator when a vehicle 102 is present and when a vehicle 102 is not present averages 469 to 1 , and is 260 to 1 in the worst case, for the antilogarithmic indicator (see levels A' and B').

In this embodiment, the base station processes the indicator received intermittently (e.g. periodically every second) from the detector 304 to identify the arrival or departure of a vehicle 102. This is achieved by averaging the indicators over a period of time, and identifying changes greater than a threshold from the average. In one embodiment, the base station compares the indicators received from more than one of the devices 104, particularly neighbouring devices, to identify changes that from the average that occur in the indicator received from one device but not another.

Other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features that are already known and which may be used instead of, or in addition to, features described herein. Features that are described in the context of separate embodiments may be provided in combination in a single embodiment. Conversely, features that are described in the context of a single embodiment may also be provided separately or in any suitable sub- combination. It should be noted that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, a single feature may fulfil the functions of several features recited in the claims and reference signs in the claims shall not be construed as limiting the scope of the claims. It should also be noted that the Figures are not necessarily to scale; emphasis instead generally being placed upon illustrating the principles of the present invention.

Claims

1. A device for detecting a moveable object, the device comprising:

a first detector arranged to detect a change in attenuation of a wireless signal at a first location; and

an indicator arranged to indicate the arrival or departure of the moveable object at the first location based on the change in attenuation detected by the first detector,

wherein the wireless signal is an electromagnetic wave attenuated by the movable object, such as a radio signal.

2. The device of claim 1 , wherein the radio signal is a navigation signal transmitted from a satellite of a global navigation satellite system.

3. The device of claim 1 , wherein the radio signal is a communication signal transmitted over a mobile telecommunication network.

4. The device of claim 3, wherein the radio signal is a communication signal transmitted by a base station of the mobile telecommunication network.

5. The device of claim 3 or claim 4, wherein the radio signal is at approximately 900 MHz, at approximately 1.8 GHz or at approximately 2.1 GHz

6. The device of claim 1 , wherein the radio signal is a communication signal transmitted over a computer network.

7. The device of claim 6, wherein the radio signal is at approximately 2.4 GHz.

8. The device of any one of the preceding claims, wherein the indicator is further arranged to indicate the presence or absence of the moveable object at the first location based on the change in attenuation of the wireless signal detected by the first detector.

9. The device of any one of the preceding claims, wherein the moveable object is a vehicle.

10. The device of any one of the preceding claims, wherein the first location is a parking space for a/the vehicle.

11. The device of any one of the preceding claims, wherein the device is battery powered.

12. The device of any one of the preceding claims, wherein the first detector and the indicator are arranged to be operational only intermittently.

13. The device of any one of the preceding claims, comprising a second detector arranged to detect the wireless signal at a second location and the indication of the arrival or departure of the moveable object at the first location is further based on the wireless signal detected by the second detector.

14. The device of claim 14, wherein the first detector is arranged to compensate changes in the magnitude of the wireless signal it detects at the first location based on changes in the magnitude of the wireless signal detected by the second detector at the second location.

15. The device of any one of the preceding claims, comprising a transmitter for transmitting the indication made by the indicator.

16. The device of claim 15, wherein the transmitter transmits the indication wirelessly.

17. The device of any one of the preceding claims, comprising a sensor for detecting CO, C0₂, N0₂, S0₂, particulates, temperature or humidity.

18. A system comprising one or more of the devices of any one of the preceding claims and one or more receivers for receiving the indication(s) made by the indicator(s).

19. The system of claim 18, comprising an RFID tag located in the movable object and an RFID reader for reading identification information from the RFID tag.

20. A method of detecting a moveable object, the method comprising:

detecting a change in attenuation of a wireless signal at a first location; and indicating the arrival or departure of the moveable object at the first location based on the detected change in attenuation, wherein the wireless signal is an electromagnetic wave attenuated by the movable object, such as a radio signal.