PROCEDURE

This invention relates to object proximity sensors particularly, but not exclusively, for installation in the ground. It is envisaged, although not essential, that these sensors may be used to detect the presence of a vehicle e.g. in a parking sensor.

Such sensors are often utilized in car parks and roads to sense vehicles parked or passing. In car parks such sensors allow a determination as to whether a certain space is occupied by a vehicle. This allows for more accurate alerts and directions for drivers to available spaces. Vehicle proximity sensors may also be installed within a road surface, utilized to detect the presence of vehicles on the road which can allow for more efficient toll systems and monitoring of traffic flow without the need for gantry

architecture.

However, vehicle sensors are often subjected to a variety of extreme conditions. Owing to their typical outdoor installation, the sensors must be capable of withstanding a multitude of weather conditions, particularly snow, rain and ice. Moisture and dust infiltrating the housing of the sensor is likely to result in the failure of its electronic systems. Furthermore the sensor must be capable of withstanding the force of heavy vehicles without fracturing of the housing. In situations where sensors are installed in the road surface of a busy road, it may be difficult to replace a faulty sensor and therefore the sensor is required to have a long lifetime (e.g. a long life power supply) as well as resilience to extreme conditions.

The Applicant has appreciated it would be advantageous to provide a sensor with a housing capable of withstanding the aforementioned extreme conditions and long lifetime so as to minimize the need for re-installation of the sensors. It would also be advantageous for the installation procedure to be relatively simply in order to allow for quick and easy installation.

When viewed from the first aspect the invention provides an object proximity sensor comprising: a proximity sensing circuit portion;

a power supply for supplying power to the proximity sensing circuit portion;

an external housing with an upper and lower part; and

an orientation sensing arrangement which is arranged to prevent or limit supply of power from the power supply to the proximity sensing circuit portion when the housing is in an initial orientation whereby the upper part is lowermost, and to permit or increase supply of power from the power supply to the proximity sensing circuit portion if the housing is inverted into a subsequent orientation whereby the lower part is lowermost.

Thus it will be seen by those skilled in the art that in accordance with at least

embodiments of the invention, an orientation sensing arrangement prevents or limits the power supply in the initial orientation, which allows battery life to be preserved before the proximity sensor is deployed such as by installing it in the ground e.g. whilst the object proximity sensor is in storage or being transported before installation. As the time from product manufacture to installation can be significant, this arrangement may save a significant amount of energy whilst the sensor is not in use and therefore significantly increase the lifetime of the device upon installation. The dependence of the power supply on the orientation also allows for an easier and quicker installation process, reducing the required human effort and period the road or car-park has to be closed for.

The sensors described herein do not require an external switch to activate the power supply to the proximity sensor portion. This removes the requirement for an opening or indentation in the external housing of the sensor which may create an area of weakness and may allow moisture to infiltrate the sensor. The use of orientation to alter the power supplied results in a device that is very intuitive to commission and install i.e.

instructions may not be required to successfully commission the device, it may be sufficient simply to remove it from its packaging, invert it to its subsequent orientation and place it in its intended installation position.

In a set of embodiments, the orientation sensing arrangement is arranged to prevent or limit supply of power from the power supply to a communication circuit portion when the housing is in the initial orientation, and to permit or increase supply of power from the power supply to the communication circuit portion if the housing is inverted into the subsequent orientation. This may further save energy whilst the sensor is not in use and therefore may increase the lifetime of the device upon installation.

In a set of embodiments the power supplied to the proximity sensing circuit portion is reduced or prevented by rotating the sensor back from the subsequent orientation to the initial orientation i.e. allowing switching off the sensor again. Such embodiments may allow for the power from the power supply to be provided temporarily depending on the orientation of the sensor, e.g. allowing for testing of the device after manufacture i.e. in the subsequent orientation where power is supplied to the proximity sensing circuit portion and preferably also a communication circuit portion, and then the device to be packaged for transportation in the initial orientation where power is once again prevented or limited. This may prevent sensors which are tested after the manufacturing process from having a significantly shorter lifetime. However, this is not essential and in other embodiments the sensor may not be switched off by rotating the sensor back from the subsequent orientation to the initial orientation. Such embodiments may be advantageous in terms of simplicity of the orientation sensing arrangement and applicable e.g. to sensors that are not required to be switched off once installed in the ground.

In a set of embodiments the proximity sensing circuit portion is arranged to determine in use whether a vehicle is present above the sensor. The vehicle may not need to be directly contacting the sensor for the sensor to detect the presence of the vehicle (i.e. a wheel of the vehicle does not need to be in contact with the sensor for the proximity sensing circuit portion to determine there is a vehicle above the sensor). There are many technologies which could be implemented for this. In a set of embodiments, the proximity sensing circuit portion comprises a magnetometer sensor. The proximity sensing circuit portion may comprise an ultrasound ranging sensor or an optical sensor. The use of an optical sensor may require a transparent window in the convex upper surface of the upper part.

In another set of embodiments, the proximity sensing circuit portion comprises a radar transmitter and receiver. In such embodiments, a radar signal may be transmitted by the radar transmitter. If a vehicle is positioned above the sensor, the signal will be reflected back to the sensor and be detected by the radar receiver. The radar transmitter and receiver may use the same aerial.

In a subset of embodiments the object proximity sensor comprises an ultra-wide band (UWB) radar transmitter and receiver. Ultra-wide band radar is particularly

advantageous as its generation requires relatively little energy and therefore increases the lifetime of the sensor.

The orientation sensing arrangement could be passive e.g. comprising a tilt switch such as mercury switch. In a set of embodiments however the orientation sensing

arrangement is actively powered. In a set of such embodiments, the power supply further provides power to the orientation sensing arrangement. Alternatively, the orientation sensing arrangement may have its own power supply. In a set of

embodiments that orientation sensing arrangement is MEMS-based.

In order to reduce the energy used prior to installation, the orientation sensing arrangement may not be continuously supplied with energy. In a set of embodiments, the orientation sensing arrangement receives a power supply at predetermined intervals e.g. 1 - 60 seconds, e.g. 1 - 20 seconds e.g. 1 -5 seconds. The skilled person will appreciate that a relatively long interval can be tolerated as it will only impact the time it takes the sensor to start up after initial installation.

An actively powered orientation sensing arrangement may comprise any of a variety of different devices for detecting the orientation of the sensor. In a set of embodiments the orientation sensing arrangement comprises a gravitational field detector preferably based on MEMS technology. This gravitational field detector may be implemented as an accelerometer for measuring the gravitational force experienced by the device. In another set of embodiments the orientation sensor comprises a gyroscope. Preferably the orientation sensor is periodically activated or sampled. In a set of embodiments the orientation sensing arrangement comprises a microcontroller. The microcontroller may receive an input from the orientation sensor and determine whether the device is in the initial or subsequent orientation. The microcontroller may then act to alter the power supply to the proximity sensing circuit portion depending on the input from the orientation sensor.

It is typically important to avoid activating the power supply to the proximity sensing circuit portion unnecessarily due to the relatively large power consumption of the proximity sensing circuit portion compared with the orientation sensing arrangement. Therefore, in a set of embodiments the microcontroller alters the power supply to the proximity sensing circuit portion only after a consistent input from the orientation sensor for a predetermined time period e.g. 10 - 200 seconds, e.g. 20 - 180 seconds, e.g. 30 - 70 seconds e.g. 60 seconds. For example, a consistent measurement for a time period of 30 seconds from the orientation sensor that the device is in the initial orientation may be required for the supply of power to the proximity sensing circuit portion, and preferably the communication circuit portion, to be limited or prevented (after having been increased or provided previously). Similarly, a consistent measurement for a time period of 180 seconds from the orientation sensor that the device is in the subsequent orientation may be required for the supply of power to the proximity sensing circuit portion, and preferably the communication circuit portion, to be limited or prevented. If the orientation sensor is continuously activated, this input might be continuous, but where the orientation sensor is activated or sampled only periodically, the power supply may be turned on or increased after a certain number of measurements indicating inversion has taken place. This helps to avoid accidental commissioning of the sensor e.g. prior to installation in a road surface.

In a set of embodiments the object proximity sensor further comprises a transmitter for transmitting information regarding whether the object, e.g. a vehicle, has been detected. This information can be transmitted to a remote server and the information may be used for example to determine the number and position of unoccupied parking sensors in a car park. This allows for more accurate information to be provided to users on the number of available sensors and their locations. In a set of these embodiments the information regarding whether the object has been detected is only transmitted when the object proximity sensors is in the subsequent orientation. This may help prevent inadvertent energy use prior to commissioning. The object proximity sensor disclosed herein may be suitable for use in multiple applications including to determine whether a vehicle is present in a parking space or to detect vehicles travelling on a road. In a set of embodiments the object proximity sensor is a parking sensor, and in another set of embodiments the object proximity sensor is used for detection and classification of vehicles travelling on a road. The object proximity sensors advantageously work in non-ideal weather conditions such a snow, rain and ice thus are advantageous for use in these applications over other devices such as cameras or laser sensors.

In a set of embodiments the object proximity sensor is designed to be installed so that at least a periphery thereof is flush with the surface of the ground. This allows the road surface to be unobstructed by their presence and removes the requirement for additional gantry architecture required for e.g. cameras.

In a set of embodiments the external housing comprises: a rigid lower part and an upper part with a resilient, convex upper surface; wherein the upper part is sealed onto the lower part using a clamping band. The external housing provides beneficial protection of electronic components of the sensor placed inside the housing by preventing the infiltration of moisture and dust.

The resilient, convex upper surface of the upper part increases the robustness of the housing as it allows the upper surface to deform under the force of a heavy vehicle which may help to reduce stress in the material and prevent fractures. The convex upper surface advantageously discourages precipitation from pooling on the sensor which can affect functioning of the vehicle sensor. For example the pooling of water on top of the sensor might hinder the functionality of the sensor and so result in a less accurate measurement of whether a vehicle is above the sensor or not.

Implementing a clamping band may ensure a controlled pressure over the area of contact between the upper part and lower part. Furthermore, the use of the clamping band may obviate the requirement to use an adhesive or o-ring to seal the upper and lower parts together to produce a secure, watertight mating. ln a set of embodiments the clamping band is made from a metal and in a preferred set of embodiments from steel. However, a skilled person will appreciate there are a variety of different materials that would be a suitable material for a clamping band such as aluminium, titanium, nylon etc.

Whilst the upper and lower parts may be manufactured from different materials, in a set of embodiments the upper and lower parts are made from the same material. In a set of embodiments the upper and lower parts are made from high density polyurethane.

The power supply for supplying power to the proximity sensing circuit portion is preferably self-contained within the housing. In a preferred set of embodiments the power supply is a battery. This allows for the option of replacing the battery when the battery is exhausted so the sensor may be reused.

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

Figure 1 a shows the external housing of a vehicle sensor in accordance with an embodiment of the invention;

Figure 1 b shows a cross-section of the external housing of the vehicle sensor; Figure 2 is a schematic block diagram of the electronic components of the vehicle sensor;

Figures 3a and 3b show the vehicle sensor in an initial orientation and a subsequent orientation respectively;

Figure 4 shows a storage or transportation arrangement of a plurality of vehicle sensors;

Figure 5 is a flow chart of the installation process of a vehicle sensor in a road surface; and

Figure 6 is an exemplary application of the vehicle sensors as parking sensors.

Figure 1a shows the external housing of a vehicle sensor 100 embodying the invention and Figure 1 b shows a cross-section through the sensor 100, which is formed primarily from an upper part 102 and a lower part 104 both made for example of a plastic material such as a high density polyurethane. A downwardly open skirt portion of the upper part 102 of the housing fits tightly over the lower part 104 and is secured using a clamping band 106..

The upper part 102 of the housing has a convex surface 1 14 as seen in both Figures 1 a and 1 b. Precipitation on top of the sensor can be problematic as it affects the

propagation of signals used for vehicle detection and can result in an inaccurate reading as to whether a vehicle is above the sensor or not. By implementing a convex surface, precipitation such as rain is prevented from pooling on top of the sensor, with the water instead running off the convex surface.

The clamping band 106 ensures a controlled pressure over the area of contact between the upper part 102 and the lower part 104. The clamping band 106 fits in a recess in the outer surface of the upper part 102. The recess helps the clamping band 106 to remain in a fixed position on the upper part 102. To fit the clamping band 106 onto the upper part 102 to secure the upper 102 and lower 104 parts in place, the clamping band may be pulled tightly around the upper part and then crimped. Alternatively, a ratchet mechanism may be implemented.

The skirt portion of the upper part 102 may be undersized to increase the tightness of the fit between the upper part 102 and the lower part 104. One or more small ridges 108, 1 10 are present on the outer surface of the lower part 104 (e.g. 1 mm height from the outer surface) to engage in corresponding grooves in the upper part 102. These ridges act to deform the upper part 102 to further tighten the fit between the upper part 102 and lower part 104. A further ridge 1 12 is located at the base of the lower part 104 for precise positioning of the upper part 102 and the lower part 104. A combination of the metal clamping band 106 and ridges 108, 1 10, 1 12 helps to produce a secure, watertight mating of the upper 102 and lower parts 104 without the need for an adhesive or o-rings. Those skilled in the art will of course appreciate that many other ways of providing a secure fit between the parts may be envisaged.

A circuit board 1 16 containing the electronics required for the vehicle sensor is located on top of the lower part 104. The circuit board 1 16 contains all the electronic

components of the sensor. A schematic block diagram of the electronic components of a vehicle sensor is seen in Figure 2. The sensor includes an orientation sensing arrangement 202 which comprises an orientation sensor such as an accelerometer 204 and a microcontroller 206. The accelerometer 204 provides an acceleration measurement to the microcontroller 206 every 5 seconds. The microcontroller 206 determines from the output of the

accelerometer 204 whether the sensor has had its orientation changed from the initial to subsequent orientation. The microcontroller 206 further tracks the number of

acceleration measurements the orientation has remained approximately constant for. This allows the microcontroller 206 to determine the orientation has intentionally been changed from an initial to subsequent orientation for installation e.g. in a road surface. The microcontroller 206 can alter the power supplied by the battery to the proximity sensing circuit portion 208 and communication circuit portion 212 depending on whether the sensor is in the initial or subsequent orientation. The accelerometer 204 and microcontroller 206 may be powered by the battery 214 also contained within the sensor.

As seen in Figure 2 the sensor further includes a proximity sensing circuit portion 208 which comprises a magnetometer 210. The proximity sensing circuit portion 208 is supplied with power from the battery 214. The power supplied is controlled by the orientation sensing arrangement 202. The magnetometer 210 detects changes in the local magnetic field caused by a vehicle disturbing the magnetic field in the vicinity of the sensor. The magnetometer 210 may then provide an appropriate signal to the communication circuit portion 212 for transmission to a remote server. The

communication circuit portion 212 may include a transmitter 218, and potentially also a receiver 220. These may use the same aerial (not shown).

The proximity sensing circuit portion 208 may comprise a separate microcontroller for determining the presence of a vehicle in the vicinity of the sensor from the

measurements from the magnetometer 210. Alternatively, the same microcontroller 106 as used in the orientation sensing arrangement may be utilized. Provision of a microcontroller allows for a binary signal to be transmitted from the communication circuit portion 212 corresponding to either the presence or absence of a vehicle. This can remove the requirement for a remote server to determine whether a vehicle is present from the magnetic field measurement. For example, the communication circuit portion 212 may simply transmit a signal to a receiver connected to a light source, where a signal indicating a vehicle is present above the sensor triggers the receiver to switch off the light source. Additional information may also be included for the benefit of the user and/or operator of the road or car park.

The sensor unit may contain additional sensors 216. Possible additional sensors may include radar, an infra-red laser or a visible light laser to increase the accuracy of the determination of the presence of a vehicle by the sensor. Other additional sensors which may be installed provide additional information which may be beneficial to the user or operator of a road/car park include temperature and pressure sensors.

Figure 3a illustrates the sensor 100 in the initial orientation in which the upper part 102 is lower- most and the lower part 104 is upper-most. As shown in Figure 4, this is the orientation in which the sensor is stored and transported prior to commissioning e.g. installation in a road surface. Figure 4 also demonstrates the sensors being stored within a storage box 402 to prevent the orientation of the sensors from changing during transportation. In the initial orientation the orientation sensing arrangement 202 is configured to prevent (or at least limit) the supply of power from the battery 214 to the proximity sensing circuit portion 208 and communication circuit portion 212. Therefore, by storing and transporting the sensor in the initial orientation, energy is conserved as none (or a limited amount) is consumed by the proximity sensing circuit portion 208 or communication circuit portion 212.

Figure 3b demonstrates the sensor 100 in a subsequent orientation in which the upper part 102 is upper-most and the lower part 104 is lower-most. Comparing this

arrangement to Figure 3a, the sensor has been rotated through 180 degrees about a horizontal axis from the initial orientation to the subsequent orientation. In the

subsequent orientation the orientation sensing arrangement is configured to permit the supply of power from the power supply to the proximity sensing circuit portion 208 or communication circuit portion 212. Therefore to commission the sensor (e.g. implement the proximity sensing purpose of the sensor), the sensor simply must be rotated through 180 degrees from its storage position in the initial orientation to the subsequent orientation.

Figure 5 is a flow chart demonstrating the installation/ commissioning procedure for a vehicle sensor. In first step 502 the sensor is stored in a storage box 402 post manufacture in the initial orientation (i.e. upside down) in order to limit or prevent power from being supplied to the proximity sensing circuit portion 208 or other circuitry in standby mode. In step 504 the sensor is then removed from the storage box by a road maintenance engineer. In step 506 the road maintenance engineer rotates the sensor through 180 degrees from the initial orientation to the subsequent orientation (i.e. the right way up). In step 508 the sensor is then placed and sealed in a hole in the ground with the top surface of the upper part of the housing of the sensor flush with the surface of the ground. After a predetermined interval of being in the subsequent orientation, in step 510, power is supplied to the proximity sensing circuit portion 208 and the communication circuit portion 212, then the sensor is commissioned i.e. functions to detect proximity of a near-by vehicle and to transmit signals indicating this. The sensor is then successful installed in the ground and can be used to detect the presence of vehicles above it.

Step 510 may further comprise the orientation sensing arrangement being in a low power mode for a predetermined interval e.g. 10 seconds. The orientation sensing arrangement then enters a higher power mode, and a measurement of the gravitational field is made, which is used to determine the orientation of the device with a degree of tolerance. The orientation sensing arrangement then switches back to the low power mode and the process is repeated. If the same orientation is recorded for 5 subsequent measurements e.g. the orientation remains consistent for 40 seconds, power is then supplied to the proximity sensing circuit portion 208 and the communication circuit portion 212 and the sensor is commissioned.

An example of the disclosed sensors implementation as parking sensors is shown in Figure 6. Within a car park 600, at least one vehicle sensor 602 is installed in each of the parking spaces 604, 606, 608, 610. The vehicle sensor 602 in parking space 604 does not detect the presence of a car, therefore transmits a signal to a remote server that there is no vehicle present in the space. The vehicle sensor 602 in parking space 608 detects the presence of a vehicle 612, and therefore transmits a signal to the remote server that there is a vehicle present in the space. The remote server may then, for example, signal light sources above an occupied space to be turned off whilst light sources above empty spaces are kept on. Typically to preserve battery life, vehicle presence information is only transmitted when the occupancy state changes.

Thus it will be appreciated by those skilled in the art that the specific embodiments of the inventive concepts described herein provides a reliable, long-life vehicle sensor which uses the sensed orientation to activate a power supply to the proximity sensing circuit portion. This may provide significant benefits over known systems. It will further be appreciated however that many variations of the specific arrangements described here are possible within the scope of the invention.