SENSOR ARRAYS, METHODS, SYSTEMS, AND DEVICES

Abstract

In one preferred form of the present invention there is provided an on-road traffic sensor comprising a body having a base and an upper portion, the body housing electronic components including a magnetometer and a battery, the magnetometer for monitoring changes in a magnetic field, the body being of slim line configuration and capable of supporting a heavy vehicle travelling at high speeds, the slim line configuration of the body being 25mm or less in height housing the electronic components, and the base being adhesively secured to a top surface of a roadway causing only minimal damage to the top surface.

Description

[Technical field]

[0001] The present invention relates to a system and method for detecting, logging, data processing, and analyzing moving objects, components thereof, and accessories thereto. In one embodiment, the present invention is useful for ascertaining vehicle movement in road traffic systems, and in devices and methodologies deployed for detecting, recording, processing, and analyzing data relating to vehicle movement, particularly, but not limited to, sensors for capturing vehicle movement data.

[0002] In another embodiment, the present invention is useful in sensing moving objects passing over or near a location on the ground surface where the sensor is mounted.

[0003] Throughout this specification, unless the context otherwise requires, the word "comprise" or variations such as "comprises" or "comprising" are understood to imply the inclusion of a specified integer or group of integers but not the exclusion of other integers or groups of integers. [Background technology]

[0004] The following discussion of the background art is intended only to facilitate an understanding of the present invention. It should be understood that the discussion is not an affirmation or admission that any of the material mentioned was part of the common general knowledge at the priority date of this application.

[0005] In order to maintain and improve the road network, it is important to monitor the road network using on-road traffic sensors.

[0006] There are a number of devices, systems and methods available on the market for traffic monitoring.

[0007] It would be advantageous if these devices could be improved, or at least provide the general public with useful options. Summary of the Invention [Means for solving the problem]

[0008] According to one aspect of the embodiments described herein, there is provided a mobile sensor comprising a body having a base and an upper portion, the body housing electronic components including a magnetometer and a battery, the magnetometer for monitoring changes in a magnetic field, the body being of a slim line configuration and capable of supporting an object traveling over the sensor at high speeds, the slim line configuration of the body being low profile to allow the object to travel relatively unhindered over the sensor at a variety of speeds, and the base being of a substantially planar configuration for adhesively securing to an upper surface of ground traversed by the object to ensure negligible damage to the upper surface.

[0009] In one embodiment, the height of the body at the site is about 25mm or less from the top surface and the speed of objects traveling over the body varies from greater than 0km / hr to 180km / hr or more.

[0010] In an alternative embodiment, the sensor is placed in a shallow recess formed in the top surface of the ground, so that the height of the body at the site is substantially flush or slightly below the plane of the top surface.

[0011] In another embodiment, the sensor includes a wireless transmitter for transmitting information based on or including data collected by the magnetometer for traffic analysis.

[0012] In a further embodiment, the electronic components include a solar cell for charging the battery, and the road traffic sensor is self-chargeable by the sun.

[0013] In another embodiment, the electronic components are arranged in a layered structure including a first layer containing the solar cell and an additional layer containing the remaining electronic components and the battery.

[0014] In a further embodiment, the further layer comprises a first layer of electronics and a second layer including a battery, the first layer having a height of 0.8 cm or less and the second layer having a height of 0.8 cm or less.

[0015] In another embodiment, the layered structure includes buffer layers, each having elastomeric properties for distributing forces across layers of the electronic component.

[0016] In a further embodiment, the buffer layer is configured to protect the electronic components from mechanical shock waves, shear forces, and mechanical stresses due to thermal expansion.

[0017] In another embodiment, the buffer layer has a vertical thickness in the layered structure of 0.1 mm or more.

[0018] In a further embodiment, the buffer layer has a Shore hardness between A10 and A20.

[0019] In another embodiment, the body includes an up-ramp, a down-ramp, and a central portion between the up-ramp and the down-ramp, the central portion for housing the layered structure.

[0020] In a further embodiment, the body includes rigid reinforcement portions extending from the sides to a central portion of the body to provide rigidity to the slim line configuration.

[0021] In another embodiment, the road traffic sensor includes a shock absorbing enclosure that surrounds the electrical components to dissipate and absorb mechanical shock waves.

[0022] In a further embodiment, the thickness of the buffer enclosure is at least 0.1 mm.

[0023] In another embodiment, the thickness of the buffer enclosure is at least 0.5 mm.

[0024] In a further embodiment, the body comprises a rigid housing having a layered structure therein with a rigid filler material filling the remaining interior cavity of the body.

[0025] In another embodiment, the on-road traffic sensor includes a sampler for sampling changes in the magnetic field by activating a magnetometer, the sampler controlling the sampling using the sampled magnetic field.

[0026] In a further embodiment, the road traffic sensor includes a sampler and a vibration sensor, the sampler for sampling changes in the magnetic field by activating a magnetometer, and the sampler controls the sampling according to vibration levels using the vibration sensor.

[0027] In another embodiment, the battery, when fully charged, provides at least 50 days of use in moderate traffic without solar charging.

[0028] In a further embodiment, the battery, when fully charged, provides at least 90 days of use in moderate traffic without solar charging.

[0029] In another embodiment, if sunny conditions exist from a few hours before noon to a few hours after noon, the solar panels can put 12 hours worth of run-time energy into the battery within an hour.

[0030] In a further embodiment, the body has a size in all three dimensions of 100 mm x 80 mm x 21 mm or less.

[0031] In another embodiment, the body has a size in all three dimensions of 100 mm x 80 mm x 15 mm or less.

[0032] In a further embodiment, the body includes an up ramp, a down ramp, and a central portion between the up ramp and the down ramp for housing electronic components, along with rigid reinforcement portions extending from the sides of the body to the central portion to provide rigidity for a slim line configuration.

[0033] In another embodiment, the road traffic sensor is configured to wirelessly transmit time-stamped magnetometer magnetic field information along with a sensor identifier.

[0034] In a further embodiment, the sensors are configured such that when operating within the sensor array to determine traffic flow, vehicle speed, or another characteristic, they are substantially independent of the placement of the sensor within the sensor array.

[0035] In accordance with an aspect of the embodiments described herein, there is provided an on-road traffic sensor including a sampler for sampling a magnetic field by activating a magnetometer, the sampler controlling the sampling using a measured characteristic.

[0036] In one embodiment, the measured property includes a sampled magnetic field.

[0037] In another embodiment, the road traffic sensor includes a vibration sensor and the measured characteristic includes vibrations measured using the vibration sensor.

[0038] In a further embodiment, the sampler is configured to use the measured characteristics to provide an early warning regarding nearby vehicular traffic, and to increase magnetic field sampling in response to the early warning.

[0039] In another embodiment, the sampler is configured to control sampling by increasing magnetic field sampling by at least a factor of two if the measured property indicates oncoming traffic.

[0040] In a further embodiment, the sampler is configured to control sampling by increasing magnetic field sampling by at least three times if the measured property indicates oncoming traffic.

[0041] In another embodiment, the sampler is configured to control sampling by increasing magnetic field sampling by at least five times if the measured property indicates oncoming traffic.

[0042] According to one aspect of the embodiments described herein, there is provided a road traffic data collection method comprising using a sampler to sample a magnetic field by activating a magnetometer and controlling the sampling in response to the measured characteristic.

[0043] In another embodiment, the measured property includes a sampled magnetic field.

[0044] In a further embodiment, the measured characteristic includes vibration measured using a vibration sensor.

[0045] In another embodiment, a method includes providing an early warning of nearby vehicular traffic and increasing magnetic field sampling in response to the early warning.

[0046] In a further embodiment, the method includes controlling sampling by increasing the magnetic field sampling by at least a factor of two if the measured property indicates oncoming traffic.

[0047] In another embodiment, the method includes controlling sampling by increasing magnetic field sampling by at least three times if the measured property indicates oncoming traffic.

[0048] In a further embodiment, the method includes controlling sampling by increasing the magnetic field sampling by at least five times if the measured property indicates oncoming traffic.

[0049] In accordance with one aspect of the embodiments described herein, there is provided an on-road traffic sensor including a sampler and a vibration sensor, the sampler for sampling changes in a magnetic field by activating a magnetometer, and the sampler controls the sampling in response to vibrations using the vibration sensor.

[0050] According to another aspect of the embodiments described herein, there is provided a road traffic data collection method comprising sampling a magnetic field using a sampler and controlling the sampling in response to a vibration sensor.

[0051] According to further aspects of the embodiments described herein, there is provided a road traffic data collection method comprising the steps of providing a sensor array of surface mounted wireless sensors on a road network, at least some of the arrays each comprising three or more surface mounted wireless sensors spaced along a corresponding segment of the road; receiving information from the sensors; and analysing the received information to determine vehicle speed information, the analysis including compensating for surface mounted wireless roadway sensors that have become detached from the road or are otherwise malfunctioning.

[0052] In another embodiment, each sensor is configured to be substantially independent of the placement of the sensor within the corresponding sensor array.

[0053] In a further embodiment, the step of analyzing the information is provided by a system separate from the sensor.

[0054] In another embodiment, the sensor array sends magnetometer information to a sensor gateway, which is independent of the placement of the sensors.

[0055] In a further embodiment, analysis of the information is performed by a system separate from the sensor gateway and the sensors.

[0056] In another embodiment, the analysis of the received information includes using a combination of sensor measurements in each array to improve accuracy.

[0057] In a further embodiment, the method includes accounting for inaccurate measurements of physical spacing between sensors in the array.

[0058] In another embodiment, the analysis of the information is performed within less than 15 minutes of the sensor sending the information.

[0059] In a further embodiment, the analysis of the information is performed within less than five minutes of the sensor sending the information.

[0060] In another embodiment, the method includes proactively issuing alerts to limit the number of surface mounted wireless roadway sensors that become detached from the roadway or are otherwise malfunctioning, allowing repair or restoration of any sensors before volume, speed, or classification / length data is lost.

[0061] In a further embodiment, the method includes proactively issuing an alert when the sensor array approaches a condition in which only a single surface mounted wireless roadway sensor is functional due to the surface mounted wireless roadway sensor becoming detached from the roadway or otherwise failing.

[0062] According to further aspects of the embodiments described herein, there is provided a system for traffic analysis including a sensor array of surface mounted wireless roadway sensors disposed within a road network, at least some of the sensor arrays including at least three surface mounted wireless roadway sensors spaced along corresponding segments of the road, a receiver for receiving information from the sensors, and an analyzer for analyzing the received information to determine vehicle speed information, the analyzer configured to compensate for surface mounted wireless roadway sensors that have become detached from the road or are otherwise malfunctioning.

[0063] In further embodiments, each sensor is configured to be substantially independent of the placement of each sensor within the sensor array.

[0064] In another embodiment, the analyzer is provided by a system facility separate from the sensor.

[0065] In a further embodiment, the system includes a sensor gateway for receiving information from the sensor array, the sensor gateway being independent of the placement of the sensors.

[0066] In another embodiment, the analyzer is provided by a system facility separate from the sensor gateway and the sensor.

[0067] In a further embodiment, the analyzer is configured to use a combination of the sensor measurements in each array to improve accuracy.

[0068] In another embodiment, the analyzer is configured to account for inaccurate measurements of physical spacing between sensors in the array.

[0069] In a further embodiment, the system is configured to analyze the information within less than five minutes of the sensor sending the information.

[0070] In another embodiment, the system includes a notifier to proactively issue alerts to limit the number of surface mounted wireless roadway sensors that become detached from the roadway or are otherwise malfunctioning.

[0071] In a further embodiment, the system includes a notifier to proactively issue an alert when the sensor array approaches a condition where only a single surface mounted wireless roadway sensor is functional due to the surface mounted wireless roadway sensor becoming detached from the roadway or otherwise failing.

[0072] According to another aspect of the embodiments described herein, there is provided a method of adding one or more sensors to a road network, the method including the steps of providing an array of surface mounted wireless sensors on the road network; for each array, physically spacing the sensors in a predetermined manner along a section of road associated with the array; receiving information from the sensors; and analyzing the received information to associate additional sensors with the array, the additional sensors being added to replace sensors that have become detached from the road or are otherwise malfunctioning.

[0073] In a further embodiment, the analysis includes monitoring the measurements to determine whether additional sensors provide time-related measurements that suggest a need to associate additional sensors with the array.

[0074] In another embodiment, within each array, the sensors are separated by a predetermined distance.

[0075] In a further embodiment the distance is between 4m and 10m.

[0076] According to one aspect of the embodiments described herein, there is provided a road traffic analysis system including: arrays of surface mounted wireless sensors located within a road network, where in each array the sensors are physically spaced in a predetermined manner along a segment of road associated with the array; a receiver for receiving information from the sensors; and an analyzer for analyzing the received information and associating additional sensors with the array, where the additional sensors are added to replace sensors that have become detached from the road or are otherwise faulty.

[0077] In a further embodiment, the analyzer is configured to monitor the measurements to determine whether additional sensors provide time-related measurements that suggest a need to associate additional sensors with the array.

[0078] In another embodiment, within each array, the sensors are separated by a predetermined distance.

[0079] In each of the methods and systems, the analysis by the analyzer is computer implemented. With a large number of sensors, automating the analysis may require a relatively large amount of computer processing power.

[0080] It should be appreciated that other forms and advantages of further embodiments will become apparent from the drawings and description of the embodiments provided below, and from the claims.

[0081] Further advantages and preferred features will become apparent from a complete reading of the drawings and specification.

[0082] In order to facilitate a better understanding of the present invention, some preferred embodiments will now be described with reference to the accompanying drawings, in which:

[0083] 1 to 10 provide different views of a road traffic sensor according to a first preferred embodiment of the present invention. [Brief description of the drawings]

[0084] [Figure 1] FIG. 2 is an end view of the road traffic sensor. [Diagram 2] FIG. 2 is a top view of the road traffic sensor. [Diagram 3] FIG. 2 is a bottom perspective view of the road traffic sensor. [Figure 4] FIG. 2 is a side perspective view of the road traffic sensor with the top portion removed. [Diagram 5] FIG. 5 is a plan view of FIG. [Figure 6] 1A and 1B are top and end views of a schematic profile of a road traffic sensor; [Figure 7] 1A-1D show various top, front and side perspective views of a road traffic sensor; [Figure 8] FIG. 7 is a more detailed view of FIG. 6. [Figure 9]FIG. 13 is another detailed end and side view of the road traffic sensor. [Figure 10] FIG. 2 is a partial cross-sectional view showing a compartment for electronic components in a road traffic sensor. [Figure 11] 1A-1D show various views of a road traffic sensor according to a first preferred embodiment of the present invention; [Figure 12] 1A-1D show various views of a road traffic sensor according to a first preferred embodiment of the present invention; [Figure 13] 13A-13C are various further views of the road traffic sensor shown in FIGS. 1 to 12. [Figure 14] 1A-1D are various views of a system according to a preferred embodiment of the present invention; [Figure 15] 2A-2D are various diagrams of a method according to a preferred embodiment of the present invention; [Figure 16] 2A-2D are various diagrams of a method according to a preferred embodiment of the present invention; [Figure 17] 2A-2D are various diagrams of a method according to a preferred embodiment of the present invention; [Figure 18] 2A-2D are various diagrams of a method according to a preferred embodiment of the present invention; [Figure 19] 1A-1D are various views of a system according to a preferred embodiment of the present invention; [Figure 20] FIG. 1 illustrates an arrangement of two on-road traffic arrays, each extending along a two-lane road. [Figure 21] FIG. 1 includes a series of photographs showing how in-road sensors are installed on a section of road. [Figure 21a] FIG. 13 shows marking a section of road for a sensor. [Figure 21b] FIG. 1 illustrates heating of a road surface. [Figure 21c] FIG. 13 illustrates placement of mounting pads. [Figure 21d] FIG. 13 illustrates heating the mounting pad to a predetermined temperature for adhesion. [Figure 21e] FIG. 13 illustrates heating the mounting pad to a predetermined temperature for adhesion. [Fig. 21f] FIG. 13 shows the placement of the sensor block onto the mounting pad for permanent adhesion to the mounting pad. [Fig. 21g] A perspective view of an in-road sensor with an aluminum housing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0085] Although each of the embodiments is specifically described, it should be understood that the invention should not be construed as being limited to the particular features or elements of any one of the embodiments, nor should the invention be construed as being limited to the features of any one of the embodiments or the variations described in connection with the embodiments.

[0086] Referring to FIG. 1, there is shown a road traffic sensor 10 according to a first preferred embodiment of the present invention.

[0087] Road traffic sensor 10 includes a body 12 having a base 14 and an upper portion 16. In an embodiment, upper portion 16 includes opposing side ramps 17, an up ramp 18, and an down ramp 20. Up ramp 18 and down ramp 20 are inversely sloping. Base 14 provides a lower surface 21, and upper portion 16 is internally filled with a rigid filler material to provide the lower surface (see FIG. 3). Lower surface 21 is configured to be adhesively secured to the upper surface of the roadway without damaging the upper surface of the roadway when sensor 10 is in use.

[0088] The body 12 houses electronic components 22 including a magnetometer 24, a battery 26, a solar cell 28, and a wireless transmitter 30. The magnetometer 24 is provided to monitor changes in the magnetic field caused by the passage of vehicles. The wireless transmitter 30 is provided to send information from the data collected by the magnetometer 24 to a central server for traffic analysis. The traffic sensor is configured to send the magnetometer information and a sensor identifier. In an embodiment, a timestamp and a gateway identifier are added by an intermediate sensor gateway.

[0089] Advantageously, the body 12 has a slim line configuration 35 and is capable of supporting heavy vehicles travelling at high speeds. The vehicles may travel at speeds of 120km / hr or more and weigh more than one tonne.

[0090] The slim line configuration 35 allows the height 37 of the body 12 to be 25mm or less and accommodates the electronic components 22. The base 14 of the body 12 is adapted to be adhesively secured to the upper surface 32 of the roadway 34 with minimal damage to the upper surface 32. Installation may take several minutes using heatable adhesive pads.

[0091] In the context of this specification, negligible damage includes a few millimeters of abrasion to the top of the top surface, as occurs with some pavement markings. Such abrasion is deemed not to significantly impair the integrity of the road surface in terms of life. In this embodiment, where the sensor 10 is affixed using an adhesive, including hot glue or a dissolvable pad, no abrasion is performed. No damage is done to the top surface 32 of the road. In any case, the body is configured to be adhesively secured to the top surface of the road without the need to damage the top surface.

[0092] When fixed to the road surface, the road traffic sensor 10 functions as a wireless sensor that reports vehicle traffic, road surface temperature, and mechanical vibration levels in the sensor's immediate vicinity. The sensor is intended to be quickly installed (within minutes) through a non-destructive installation and removal process utilizing a permanent or semi-permanent adhesive, such as a butyl adhesive pad, and to have negligible impact on the asphalt or concrete road surface.

[0093] The electronic components 22 are arranged in a layered structure 36. The layered structure 36 includes a first layer 38 including the solar cell 28 and a further layer 40 including the remaining electronic components and the battery 26. The further layer 40 includes all electronics 46 of the electronic components except for the solar cell 28. The electronics 46 is provided as a printed circuit board with circuitry and the battery 26.

[0094] In an embodiment, the first layer 38 and the further layer 40 each advantageously have a height of less than 0.8 mm.

[0095] As shown, the solar cell 28, electronics 46, and battery 26 are in a slim line configuration within the layered structure 36 in that each is narrower than its width and extent. As explained, the slim line configuration 35 allows the body 12 to have a height of 25 mm and accommodates the electronic components 22.

[0096] The body 12 resembles a rigid pavement marking in the shape of a truncated pyramid and includes side ramps 17, on-ramp 18, and off-ramp 20. The road traffic sensor 10 is self-charging via solar cells 28, a battery 26, and the sun. The road traffic sensor 10 is advantageously capable of relaying collected information over an extended period of time.

[0097] In another preferred embodiment, a slim line configuration 35 allows the body 12 to have a height of 20 mm or less and accommodates the electronic components 22. In yet another embodiment, the up ramps 18 and down ramps 20 are not present. Rather, the upper portion 16 comprises a thin, raised housing for the electronic components 22.

[0098] The layered structure 36 includes several buffer layers 48. Each buffer layer 48 advantageously has elastomeric properties for distributing forces among the layers of electronic components 22 within the layered structure 36.

[0099] The buffer layers 48 are configured to protect the electronic components 22 from mechanical stresses caused by mechanical shock waves, shear forces, and thermal expansion associated with a typical road traffic environment. In this embodiment, the buffer layers 48 each have a Shore hardness of between A10 and A20.

[0100] In an embodiment, a cushioning enclosure 50 surrounds the electronic components 22 to dissipate and absorb mechanical shock waves. The cushioning enclosure comprises a block of elastomeric material that encases the electronic components 22.

[0101] A central portion 54 is provided between the up-ramp 18 and the down-ramp 20. The central portion 54 includes a sidewall 55 and is provided to house the layered structure 36.

[0102] The body 12 includes a rigid reinforcement portion that extends from a side 56 of the body 12 to a side wall 55 of the central portion 54 to provide rigidity to the slim line configuration 35 .

[0103] The shock absorbing enclosure 50 directly contacts the rigid plastic of the body 12 which provides the upper portion 16. The body 12 includes the base 14 and provides a rigid housing 58 which contains the layered structure 36. A rigid filler material fills the remaining interior cavity 60 of the body 12 to form the road traffic sensor 10.

[0104] When fully charged, the battery 26 provides at least 75 days of use of the road traffic sensor 10 in medium traffic without solar charging, in other words, the road traffic sensor 10 can function for at least 2.5 months without solar charging.

[0105] If sunny conditions exist from a few hours before noon to a few hours after noon, solar cell 24 can input 12 hours worth of run-time energy into battery 26 within an hour.

[0106] In an embodiment, the size of the body in three dimensions is approximately 100mm x 80mm x 21mm in three dimensions. Of course, various configurations are possible, including a much thinner body without the lamp.

[0107] The road traffic sensor 10 includes a sampler 64 configured to sample changes in a local magnetic field 68 caused by a vehicle 65 moving over the sensor 10. The sampler 64 is configured to selectively activate the magnetometer 24 and to control the sampling frequency using the sampled magnetic field.

[0108] More specifically, the sampler 64 is configured to monitor a magnetic field 68 by activating a magnetometer to sample according to a first frequency region 70. If the magnetic field is sampled and found to be indicative of the vehicle being moved, the sampler 64 advantageously changes the sampling to a higher frequency region 72. In this manner, it becomes possible to sample at a much higher frequency without unduly impacting battery life.

[0109] As a vehicle 65 drives over the sensor 10, the resulting local magnetic field may, for example, follow waveform 74. Upon sensing a perturbation in the magnetic field, the sampler 64 switches from a first sampling frequency 76 to a second, higher sampling frequency 78, and then switches back to the first sampling frequency 76. The switch back to the first sampling frequency 76 may occur once the magnetic field appears to have stabilized.

[0110] Magnetometer information generated using the sampled magnetometer waveforms is measured by the road traffic sensors 10 and sent along with a sensor identifier to the sensor gateway. The sensor gateway sends the sensor identifier, magnetometer information and a timestamp to an external server for processing. In this embodiment, this is done in near real time.

[0111] According to a second particular embodiment of the present invention, there is provided a road traffic sensor 100. The road traffic sensor 100 includes a sampler 102, a magnetometer 104, and a vibration sensor 106. The sampler 102 is provided for sampling changes in the magnetic field by activating the magnetometer 104 and sampling its output.

[0112] Advantageously, the sampler is further configured to sample changes in vibration level by activating the vibration sensor 106 and sampling its output. Additionally, the sampler 106 is advantageously configured to control the sampling of the magnetometer 104 in response to the vibration level measured using the vibration sensor 106. This is believed to be advantageous because the sampler should be able to change to higher frequency regions well before perturbations in the magnetic field are sensed. In both embodiments, the sampler uses the measured characteristic 108 to control the sampling and activation of the magnetometer.

[0113] In a second embodiment, the measured characteristic 106 is advantageously used to provide an early warning regarding nearby vehicular traffic and in response increases magnetic field sampling. The magnetic field sampling is performed at a first frequency. If the measured characteristic indicates oncoming traffic, the frequency is advantageously increased by a factor of two. In this manner, a road traffic data collection method 110 is provided.

[0114] The road traffic sensor 10 is configured to wirelessly transmit time-stamped magnetometer magnetic field information along with a sensor identifier. The sensor 10 may be used to provide vehicle speed information by forming part of a sensor array comprising a series of road sensors 10' extending along a second road. In particular, the sensor 10 is configured to be substantially independent of the placement of the sensor within the sensor array when used to determine traffic flow, vehicle speeds, or other characteristics.

[0115] In another embodiment, a road traffic sensor is provided that includes a low power microcontroller such as a Microchip SAM, a 3-axis magnetometer, an ISM band (866 MHz, 920 MHz) radio, a solar charging battery management device, and an ultra-low power DC to DC converter.

[0116] The sensor is advantageously capable of measuring the simulated road surface temperature using an integrated thermometer. In an embodiment, the temperature measured is the temperature of the magnetometer components under the temperature of the potting compound surrounding the magnetometer, which will be the temperature of the device's surroundings, but likely with hysteresis effects due to the combined effect of the heat capacity of the potting material and its thermal conductivity.

[0117] The sensors can be installed directly on the road surface and have the typical shape and appearance of raised pavement markings within the lane. They communicate via ISM (915MHz) or SRD (868MHz) band radio with a gateway device installed in the general vicinity of the sensor, which forwards messages to services operating in the online environment and uses the gateway device as an accurate time source.

[0118] The components contained in one embodiment include a solar panel with approximate dimensions of 75mm x 29mm x 1.5mm (OCV between 3V and 5V), a printed circuit board with approximate dimensions of 40mm x 28mm x 3mm (including component height), a 3.2V 500mAh LiFePO4 battery with approximate dimensions of 35mm x 25mm x 7mm, a piezo film or diaphragm type vibration transducer less than 25mm x 25mm, and low current (diameter 1mm or less) insulated wires required to connect the battery and solar panel to a circuit.

[0119] The combination of the battery and solar panel is intended to provide enough capacity to run the device indefinitely (until component fatigue causes the device to fail or malfunction). In this embodiment, a fully charged battery will last approximately 90 days (~2200 hours) without sunlight. In a sunny climate such as Perth, Australia in summer, it takes about 3 days for the battery to fully charge in direct sunlight (maximum charging current is about 50mA).

[0120] A 3-axis magnetometer with arbitrarily oriented X, Y, and Z axes is used to measure the variations in vector direction and magnitude of the local magnetic field caused by vehicle motion, and from those variations detect the presence of a vehicle in the immediate vicinity of the device, its approximate heading, and generate an overall identifier for the vehicle.

[0121] A piezo vibration transducer is used to provide early warning of nearby vehicular traffic so that the high sampling rate mode of the magnetic sensor can be pre-triggered. The vibration transducer is also utilized to provide a relative measurement of the vibration level experienced by the nearby road surface, which is reported to an online service for transmission to road management authorities, thus providing additional data to estimate the remaining life of the nearby road surface. The ISM / SRD radio device provides ultra-low power communication with a gateway device in the approximate vicinity.

[0122] The housing has an outer shell constructed of a hard, sturdy, optically transparent, UV stable plastic, in this embodiment polycarbonate, although polycarbonate is preferred, in other embodiments MABS (methyl methacrylate acrylonitrile butadiene styrene) is used.

[0123] The top part of the outer shell (above the central cavity) is 4mm thick, the outer and angled walls are 3mm thick, and the inner struts are 2mm thick. The outer largest dimensions of the outer shell are 100mm x 80mm x 21mm, and the central cavity is 76mm x 30mm x 17mm.

[0124] Adhesion of the underside 21 of the base 14 to the road surface is accomplished using a "butyl pad" which is heated to its melting point by a torch and cooled very rapidly, resulting in virtually instantaneous adhesion. The primary installation time is the time it takes to heat the road surface and butyl pad to the required temperature, typically less than 60 seconds.

[0125] The electronic components 22 are housed within the central cavity of the outer housing and are each embedded within (and separated by) a layer of a very soft (Shore hardness A10 to A20), optically transparent and UV stable polyurethane compound such as Electrolube UR5048. The remaining cavities within the outer housing are then filled with a very hard, very strong, opaque epoxy such as MG-832HT from MG Chemicals.

[0126] The hard, strong, opaque epoxy provides compressive and tensile strength to ensure that the housing is not significantly compressed or damaged by mechanical forces generated by vehicle tires impacting the device, whether at low or high speeds, or when the vehicle tires (cars, trucks, and buses) are momentarily parked directly above the device. The inner soft polyurethane compound protects the sensitive electronic components through dispersion and absorption (energy stored in the material lattice, which compresses and / or distorts, in accordance with the known behavior of elastomers).

[0127] The solar panel is mounted proximate to the top of the outer housing, and the circuit board and battery are mounted adjacent to the solar panel below. In some embodiments, the thickness of the soft polyurethane layer between the outer shell and the solar panel is approximately 0.2 mm to 0.6 mm. In some embodiments, the thickness of the soft polyurethane layer between the solar panel and the circuit board, where the component is mounted facing the base of the device, is approximately 0.8 mm to 1 mm. In some embodiments, the thickness of the soft polyurethane layer between the solar panel and the battery ranges from 0.2 mm to 1 mm. The thickness of the soft polyurethane layer on the component side of the circuit board is at least 2.5 mm and can be up to 5 mm thick. The thickness of the soft polyurethane below the battery is 0.5 mm to 1 mm.

[0128] The battery and PCB are next to each other under the solar panel and separated from the solar panel by roughly 1mm of soft elastomer compound. The closest space between the battery and PCB is about 0.5mm to 1mm and is also filled with elastomer compound. This battery only has a thin layer of 0.5mm of elastomer compound between the battery and the hard epoxy that fills the remaining space down to the base of the sensor. The bottom side of the PCB containing the electronic components has a thicker layer of elastomer compound (at least 2.5mm, maximum 5mm) because that area is most susceptible to mechanical stresses (which can also be caused by thermal expansion).

[0129] As discussed, the housing protects the electronics from the mechanical impact of a tire hitting a stud. In this embodiment, protection is achieved through a layout combined with the use of multiple potting compounds with soft, flexible compounds (such as Electrolube UR5048) that directly surround the electronics, dispersing and absorbing mechanical shock waves (thus reducing the chance of physical destruction of the PCB and components). The outer layer of potting compound provides the stiffness to withstand static compression (as opposed to shock waves that propagate very well through such materials) and bending force (to withstand breaking and bending). The soft inner compound is designed to reduce the magnitude of the shock waves propagating through the hard outer encapsulant.

[0130] In this embodiment, the aforementioned layered structure is provided in a rectangular shape.

[0131] In another embodiment, the housing is replaced with a graded rubber mat of a shape similar to that of the outer shell / housing described.

[0132] In various embodiments, the magnetometer information sent by the sensor does not include the complete waveform. Rather, the sensor is configured to send various characteristics derived from the complete magnetometer waveform, including the reference points and signature. In one embodiment, the information sent includes a sensor identifier, an activity start timestamp, an activity stop timestamp, an indication that the magnetic field was perturbed from quiescent before the activity started, an indication that the magnetic field is still perturbed from quiescent after the activity has stopped, and an estimated center of gravity reference point.

[0133] One approach considered involves computing an ensemble-weighted average index for the complete waveform (with weighting given by the magnitude of the sample at each index) and then computing a timestamp at that index, which can be thought of as analogous to computing the center of gravity of a rigid body.

[0134] It is also possible to include the waveform signature. One technique considered is to take a DCT-II transform of the first 128 samples from the first peak or valley found in the waveform (with zero padding if the waveform is not long enough), compress the magnitude, and then generate a small vector by combining the first 4 to 12 coefficients of the transform.

[0135] In a further embodiment, a slim-line configuration is provided that includes a reinforced body and electronic components that advantageously do not require physical damage to the upper roadway, the electronic components include a magnetometer, a solar cell, and a battery, the components include a module that is inserted into a portion of the reinforced body, the reinforced body includes a base and two ramp portions that support over one ton of vehicular traffic, the base is configured to be adhesively secured to the upper roadway, and the battery has a height of 10 mm or less.

[0136] Advantages of the device include its ability to provide measurements without damaging the road surface, and it can accommodate large vehicles, including those weighing over one tonne, in the road transport industry where extended measurement times are particularly important.

[0137] According to a further embodiment, a road traffic data collection method 150 is provided. At block 152, the method 150 includes providing sensor arrays 154 of surface mounted wireless sensors 156 on a road network 158 near several intersections, at least some of the arrays 154 each comprising three or more surface mounted wireless sensors 156 spaced along a corresponding segment of the road. In an embodiment, four sensors 156 are positioned in each array 156 in the center of the lanes of various two-lane roads. The sensors 156 in each array 154 communicate with an adjacent sensor gateway 153.

[0138] At block 155, the method 150 includes receiving information from a sensor 156. The information includes magnetometer information, sensor identification information, and timestamp information.

[0139] At block 157, the method 150 includes analyzing the received information to determine vehicle speed and other information. At block 157, the analysis includes compensating for surface mounted wireless roadway sensors that have become detached from the roadway or have otherwise failed. In this regard, it should be appreciated that failure of a sensor 156 may be a relatively unlikely event compared to the sensor becoming detached from the roadway due to the adhesive nature of the non-excavation fixing of the sensor to the roadway surface.

[0140] The method 150 maintains an incoming information cache, where the magnetic waveform information is provided with a sensor identifier, a timestamp, and a gateway identifier. To determine the corresponding sensor array, the method 150 searches the sensor identifier and sensor array store. This allows an analysis based on the gateway ID, timestamp, and magnetic waveform information of each sensor array. The analysis includes identifying the vehicle and the ordered adjusted timestamp of the array. If the adjusted timestamp does not meet the criteria and indicates that the sensor has been removed from the road surface, the system adjusts it to best estimate the vehicle speed from the remaining adjusted timestamps. Various correlation techniques may be applied to identify the vehicle and the missing expected sensor measurements.

[0141] Providing an array 154 of three or more surface mounted wireless sensors 156 spaced along the road is believed to provide significant advantages in the method 150. First, it is possible to determine information about speed from pairs of functioning sensors in each array. In an array with n functioning sensors, there will be n(n-1) / 2 pairs, each providing a measurement. In an embodiment, the sensors in the array are installed at a set distance from each adjacent sensor in the series. The set distance for the method 150 is 5m.

[0142] In one embodiment, the analyzer functions as follows: The analyzer collects information from a sensor using a sensor identifier. The analyzer waits 166 a set period of time. In block 168, the analyzer determines all sensors in the sensor array that correspond to the sensor identifier.

[0143] After this period of time has elapsed, the analyzer determines whether any measurements have been received from the sensor that indicate the sensor has been removed from the road surface.

[0144] This determination is typically accomplished by analyzing multiples of a set time interval between measurements when a vehicle is observed passing over the sensor array. The method also advantageously captures acceleration by looking for an increase in the time interval between measurements. If the time interval is significantly longer than expected, this is an indication that the sensor has been removed from the road surface.

[0145] The analysis determines the vehicle's travel speed from the measurements based on the set spacing of the spaced sensors in the array. The information is analyzed to determine spurious measurements and to account for known alignment of 5 meters between sensors within the set distance between particular sensors. Advantageously, the system is configured to characterize changes in spacing between sensors over time. Notably, in another embodiment, the distance between sensors is determined using GPS information recorded in another manner and sent by the sensors. In this embodiment, it is not preferred to provide a GPS for each sensor. In other embodiments, it is preferred to provide a GPS for each sensor.

[0146] By having an array of nodes each with at least three sensors, accuracy should be increased because there are n(n-1) / 2 pairs of sensors in each array of n functioning sensors from which a velocity measurement can be determined.

[0147] According to a further preferred embodiment of the present invention, there is provided a system 200. The system 200 includes a sensor array 202 of surface mounted wireless roadway sensors 204 located within a road network 206, at least some of the sensor arrays 202 each comprising at least three surface mounted wireless roadway sensors 204 spaced along a corresponding segment of the road. The system includes an online server facility 205 including a receiver 208 for receiving information from the sensors 204 and an analyzer 210 for analyzing the received information to determine vehicle speed information. The analyzer 210 is configured to compensate for surface mounted wireless roadway sensors that have become detached from the roadway or are otherwise malfunctioning.

[0148] The functionality of system 200 is consistent with method 150. As with method 150, each sensor 202 effectively transmits magnetometer waveform information and sensor identification information along with a timestamp. Each sensor is substantially independent of its placement within a corresponding sensor array as known by analyzer 210. Analysis is performed with analyzer 210 located in an on-line system separate from sensor 204.

[0149] The system 200 includes several gateways 214 that communicate with the sensors 204 in each sensor array 202. The sensors 204 in each sensor array 202 send magnetometer information to the sensor gateway 214, which is independent of the placement of the sensors 204. The online system 205 and the analyzer 210 are separate from the sensor gateways 214 and the sensors 204.

[0150] The analyzer 210 is configured to analyze the received information using a combination of the sensor measurements of each array to improve accuracy. As before, the analysis takes into account the imprecisely configured physical spacing on the corresponding section of road between the sensors of each array.

[0151] The analysis is carried out in real time, ideally within less than five minutes after the sensors send information providing traffic-related information (vehicle speed-related information).

[0152] The system includes a notifier 216 that proactively issues alerts 218 to limit the number of surface mounted wireless roadway sensors that become detached from the roadway or are otherwise malfunctioning. This is considered advantageous because it allows a maintenance company (responsible for a particular section of roadway) to be notified that a surface mounted sensor has become detached from the roadway (or is malfunctioning).

[0153] Additionally, in one embodiment, speed-related information is maintained by a notifier 216 that proactively issues an alert when the sensor array approaches a state where only a single surface-mounted wireless roadway sensor is functional due to a corresponding surface-mounted wireless roadway sensor in the array becoming detached from the roadway (or failing).

[0154] The system 200 advantageously uses an on-road traffic sensor 10 for each of the wireless roadway sensors 204. Unlike conventional road traffic sensor systems, the use of on-road traffic sensors means that installation, maintenance and replacement of the sensor nodes is relatively simple through the use of heatable adhesive pads and no excavation or repair of the road surface is required.

[0155] In a related embodiment, sensors are surface mounted and arranged as a redundant array of devices within a lane. As sensors become detached from the road over time, the system can advantageously operate with a built-in level of redundancy. The physical sensors are independent of their own placement and adjacent peers, the gateways are independent of the placement of sensors and physical road lanes, and no processing is performed at the sensor or gateway level; the sensor array configuration and processing is applied solely to the cloud-based environment.

[0156] One mapping technique, according to one embodiment, involves mapping data produced by individual sensors to a virtual device array. More specifically, the technique involves taking individual sensor data and analyzing each sensor time series with other sensor time series from other sensors in the same array lane to produce individual counts, rates, and classifications. The algorithm employed detects and compensates for missing sensors during the correlation process on the fly, providing the following modes of operation: --- Healthy and Redundant: All devices are active. No faults were detected. --- Degraded, Redundant: At least three sensors are active and the device is missing. One or more sensors have failed, but enough devices are operational to provide redundancy. --- Degraded, Active: 2 sensors All but two sensors fail. The array continues to operate normally, but redundancy is lost. Any further sensor failures will affect the array. --- Degraded, Error: 1 sensor The array can no longer operate with high precision and the data produced is now limited to counts. --- Fault Occurs: All sensors are missing Currently, live data is not available. --- Reporting degraded status allows the sensor to be repaired / restored before volume, velocity, or classification / length data is lost.

[0157] In yet another embodiment of the present invention, a method of adding one or more sensors to a road network is provided, the method comprising the steps of providing an array of surface mounted wireless sensors on the road network; for each array, physically spacing the sensors in a predetermined manner along a section of road associated with the array; receiving information from the sensors; analysing the received information and associating additional sensors with the array, the additional sensors being added to replace sensors that have become detached from the road or are otherwise faulty.

[0158] This method is considered advantageous because it does not require the additional sensors to be manually associated with the array by the installer. The installer simply places the new sensor in a suitable position relative to the existing array and the system correlates the measurements and associates the additional sensor with the existing array. If all sensors of an array are removed from the road surface, there will be no measurements to analyze. For this reason, there must be at least one existing functioning sensor array in a suitable position on the road surface. If not, the array must be added manually by manually specifying its location on the road network.

[0159] The analysis includes monitoring the measurements to determine whether an additional sensor not associated with the array provides a time-related measurement that suggests the additional sensor should be associated with the array. One particular embodiment has a constraint that within each array, the nodes are a predetermined distance apart.

[0160] Another embodiment includes a road traffic analysis system including: an array of surface mounted wireless sensors located within a road network, where in each array the sensors are physically spaced in a predetermined manner along a segment of a road associated with the array; a receiver for receiving information from the sensors; and an analyzer for analyzing the received information and associating additional sensors with the array, where the additional sensors are added to replace sensors that have become detached from the road or are otherwise malfunctioning.

[0161] The analyzer is configured to monitor the measurements to determine whether the unassigned sensor provides a time-related measurement that indicates that the unassigned sensor should be associated with the array.

[0162] In the system and method, the sensor devices are involved in a communication process and automatically associated with a communication gateway. The association with the communication gateway utilizes a signal strength technique to select a gateway with a good communication signal. The sensor is ideally associated with two or more gateways, one as a primary gateway and the others as secondary backup gateways. Advantageously, the system is configured to automatically assign arrays to sensors using correlation techniques. This is considered advantageous because when some of the sensors are out of their position on the road and / or removed from the field, the process of adding replacement sensors becomes a process of simply fixing the replacement sensors without associating the array with a sensor identifier in the online system.

[0163] The analysis includes the system identifying a measurement pattern that is indicative of a sensor being added. The indication includes monitoring for consistent measurements that match an expected measurement pattern associated with vehicle movement.

[0164] For example, if the system indicates that there is an array with two nodes, sensor ID 56846778489 and sensor ID 4649815687, and unassigned sensor ID 5787638877 consistently provides measurements that indicate the nodes are separated in a given state by a vehicle traveling over each of these sensors, then unassigned sensor ID 5787638877 will be associated with the array.

[0165] Embodiments may also include the gateway adding a gateway identifier to sensor communications with the analyzer to assist the analyzer in filtering out apparently irrelevant sensors and / or irrelevant arrays.

[0166] For security reasons, the method and system may require authentication of sensors within the system.

[0167] In one embodiment, an authorization store is maintained for a particular gateway that ensures that only a particular sensor can be "associated" with a given gateway for communication with the main system.

[0168] In one embodiment, a sensor requires a "gateway" that is known to be active in order to operate. This is required a) when the sensor wakes up, or b) if a gateway has not yet been found and a retry process is initiated, or c) if a previously utilized gateway has not responded for a significant period of time. If either (a), (b), or (c) is true, the device scans a predefined set of (utilized) wireless channels, and if one or more gateways respond, it begins using the gateway with the strongest wireless signal strength (as determined by the response to the channel scan). If no gateway responds, the device goes into an offline ultra-low power mode and continues to attempt on a predefined schedule (per (b) above).

[0169] In other embodiments, the operator must specify which sensors belong to which array in the online system, and the order of the sensors within the array is determined automatically.

[0170] In a third particular embodiment, the system is embodied in a telemetry system that includes base station units associated with an array of sensors, whereby the base station units are based on a combination of custom and off-the-shelf hardware and run proprietary software within a Linux® operating environment.

[0171] The base station units communicate with cloud services that are the primary destination for all sensor data. These services aggregate, historize, and process the sensor data to create vehicle volume, speed, and classification data.

[0172] The system is designed to produce near real-time trend data at custom intervals ranging from minutes to hours, enabling clients to monitor traffic flows in near real-time.

[0173] The roadway sensors feature a cast aluminum housing for robustness and resistance to wear in traffic, which houses the LED drive circuitry and highly sensitive, fine-pitch electronics.

[0174] Correcting and combining the three axes into a single data stream addresses the problem of a running signal median that is matched to post-processed magnetometer data to remove the running median, which addresses perturbations of the Earth's geomagnetic field due to the vehicle, and includes employing an alternative housing to that described in the previous embodiment.

[0175] Previously, a clear polycarbonate shell was used to pack the components and then potted with resin to achieve a (mostly) RF transparent housing. In this embodiment, this RF transparent housing is replaced with a cast aluminum housing that is not RF transparent, thus necessitating a redesign of the antenna aspect of the system. Thus, an ISM band RF antenna is incorporated within a resin-filled cavity on the exterior of the cast aluminum housing, allowing RF signals to remain communicable within the 100m range that the cavity has line of sight to the RF base station device.

[0176] To maintain acceptable impedance, sufficient efficiency and absence of reflection-induced multipath fading, a PCB type antenna is used, which is easily assembled in a specific cavity on a given cast aluminum housing to allow the system to communicate on a target-by-target basis.

[0177] An algorithm is provided that embodies enhanced magnetic data analysis to optimally employ an effective sampling rate and provide a method to distinguish between vehicles in a lane and those in adjacent lanes. This is accomplished by examining the relative average power of the delta in each of the magnetometer's x-, y-, and z-axes. It is assumed that the magnetometer's x-axis is perpendicular to the traffic flow, the y-axis is parallel to the traffic flow, and the z-axis is up-down.

[0178] From this, the relative movement of each axis over the life of the vehicle (delta relative to the baseline) is: (a) causes fluctuations of only one sign (positive or negative) on the x-axis, (b) causes relatively weak fluctuations in the y-axis, (c) It causes relatively weak fluctuations in the z axis.

[0179] Data analysis shows that vehicles within the lane cause strong y-axis and z-axis variations, while vehicles not passing directly over the magnetometer cause weaker variations.

[0180] Therefore, the thresholds are empirically determined through large-scale data analysis that provides a practical mechanism for making statistically relevant predictions regarding a vehicle's in-lane / out-of-lane status.

[0181] This methodology utilizes the derivative of each axis of the magnetometer signal separately, in contrast to previous methods that utilize a joint vector norm from offset-removed axis signals.

[0182] It should be noted that the x-axis and y-axis variations are largely uncorrelated with the in-lane or out-of-lane status of the detected vehicle. From this, it can be seen that in-lane vehicles generate relatively strong z-axis variations both above and below the average value of the z-axis signal, while out-of-lane traffic vehicles (when the signal perturbation occurs) perturb the z-axis signal in only one direction (either above or below the average value, depending on the orientation of the sensor axis at the installation location and the magnetic tilt angle of the Earth). Thus, this methodology utilizes tracking the z-axis perturbations over the lifetime of the vehicle and only admitting the vehicle as in-lane if z-axis perturbations of both positive and negative signs of sufficient amplitude are detected.

[0183] In a further embodiment, a vehicle record generation process is provided that includes specially programmed low processing power / low memory algorithms that allow the vehicle generation process / computation to be moved to the base station edge device so that the final vehicle data (single timestamp, length, speed, etc.) is pushed to the cloud server rather than all the individual events from the multiple associated sensors from which the vehicle record is generated. This can reduce costs by reducing computation time and space requirements within the associated cloud services and can also be used to collocate signage at the installation location to display vehicle information in true real-time.

[0184] Additionally, in other embodiments, the raw vehicle length is calculated from multiple associated sensor events. Thus, an algorithm is implemented to compensate for the raw vehicle length using an iterative design process, resulting in a corrected vehicle length with acceptable error margins from the results of existing techniques.

[0185] Next, the installation of sensors constructed with an aluminum housing unit according to this embodiment in an in-road array as shown in FIG. 21 will be described.

[0186] Further, as shown in Figure 21a, the process begins with marking each sensor location in the center of the traffic lane. For speeds below 60km / h, a spacing of 3m is used between sensors. For speeds above 60km / h, a spacing of 4m is used. Loose material is removed from the lane to allow for proper attachment of the mounting pads.

[0187] The road surface around where each sensor will be installed is heated to 140°C / 285°F by a gas burner, as shown in Figure 21b. Mounting pads are placed in the heated areas, ensuring that the correct spacing is maintained and that each pad is aligned with the road direction, as shown in Figure 21c.

[0188] Use a gas burner to heat the mounting pad to a final temperature of at least 240°C / 465°F as shown in Figures 21d and 21e. When the pad is sufficiently heated it should have the appearance of a viscous liquid and may emit a small amount of smoke.

[0189] The sensor unit is placed in the center of the pad, with a small portion of the pad left protruding evenly around the edge, as shown in Figure 21f. Pressure is applied by gently standing on the studs to ensure alignment is maintained.

[0190] Figure 21g shows the resulting in-situ sensor unit.

[0191] While each of the above described embodiments show a position of the sensor over the road surface with minimal damage and interference to the road surface, in cold climates prone to snowfall and ice, snowplows may be deployed to scrape the road surface to remove snow and ice from the road surface, and therefore it is not feasible to have the sensor unit protrude above the road surface, or the sensor unit would interfere with the operation of the snowplow.

[0192] In these environments, the sensor unit is actually embedded into the road surface such that the top surface of the sensor unit is flush with or slightly lower than the road surface. In these situations, it is important to minimize the height of the sensor, which requires that the road be scraped away to create a small depression, within which the sensor can be optimally positioned to fit into a recess formed in the road and avoid contact with snowplows or other road scrubbing machinery.

[0193] Applicant believes that with sufficient computational power, it may be possible in the future to automatically determine sensor-to-array mapping (in addition to ordering within the array). Such a system should be reliably possible even with a relatively limited number of arrays, especially if the closest gateway is selected based on signal strength and the gateway identifier is used as part of the correlation that associates added nodes with their identifiers.

[0194] As will be apparent, each of the systems and methods includes automated computer-implemented systems and methods for wireless communication and analysis. In various preferred embodiments, matching of measurements is based on a predefined sensor spacing, such as 5m spacing. Various matching (analysis) techniques may be employed to determine speed-related and other information using the n sensors in each sensor array.

[0195] As will be apparent, various modifications and equivalents may be provided without departing from the spirit and scope of the present invention, which includes modifications within the scope of the appended claims, as well as all modifications, alternative constructions and equivalents.

[0196] There is no intention to limit the invention to the specific embodiments shown in the drawings, the invention should be construed in its entirety as being beneficial to the applicant and the invention.

[0197] In this specification, the presence of a particular feature does not preclude the presence of additional features. The words "comprising," "including," "or," and "having" are to be interpreted in an inclusive sense rather than an exclusive sense.

[0198] It should be recognized that any discussion herein is intended to explain the context of the invention and should not be construed as an admission that the material discussed formed part of the prior art base or relevant general knowledge in any particular country or region.

Claims

1. A mobile sensor placed on a ground surface traversed by a mobile object, a body having a base and an upper portion; the body housing electronic components including a magnetometer and a battery, the magnetometer for monitoring changes in a magnetic field; the body is capable of supporting a moving object traveling at high speeds over the sensor, and has a slim-line configuration and low profile so that the moving object can travel relatively unimpeded over the sensor at a variety of speeds; the base is of a substantially planar configuration for adhesive fixation to the surface to ensure minimal damage to the surface; a wireless transmitter for transmitting information based on or including data collected by said magnetometer for traffic analysis; the electronic components include a solar cell for charging the battery, and the sensor is self-chargeable by the sun; A mobile sensor, wherein the electronic components are arranged in a layered structure including a first layer including the solar cell and a further layer including the remaining electronic components and the battery.

2. the layered structure includes buffer layers, each buffer layer having elastomeric properties for distributing forces to the layers of the electronic component; The mobile sensor of claim 1 , wherein the body includes an up ramp, a down ramp, and a central portion between the up ramp and the down ramp, the central portion for housing the layered structure.

3. a sampler for sampling changes in the magnetic field by activating the magnetometer; The sampler uses the sampled magnetic field to i) To provide early warning of the presence of nearby traffic, and ii) so as to increase the sampling of magnetic field changes accordingly; The mobile sensor of claim 1 , wherein the sampling is controlled.

4. The mobile sensor of claim 1 , wherein the wireless transmitter is configured to wirelessly transmit time-stamped magnetometer magnetic field information along with a sensor identifier.

5. 10. The mobile sensor of claim 1, wherein the sensor is configured such that its operation within the sensor array to determine traffic volume, mobile speed, or another characteristic is substantially independent of the placement of the sensor within the sensor array.

6. A method for collecting traffic data of a mobile object, comprising: providing a surface-mounted sensor array of wireless sensors on a surface that will be traversed by a moving object; comprising a plurality of surface-mounted wireless sensors in some of the arrays; spaced apart surface-mounted wireless sensors along corresponding sections of a road; generating information about a magnetic field waveform measured by a magnetometer; receiving information from the surface-mounted wireless sensor; analyzing the received information to determine vehicle volume information; at least some of the arrays comprise two or more surface-mounted wireless sensors; and wherein said analyzing includes ensuring that wireless sensors are detached from said surface or that they are malfunctioning.

7. The method of claim 6 , wherein each sensor is configured substantially independent of its placement within the corresponding sensor array.

8. 7. The method of claim 6, including proactively issuing an alert when approaching a condition where only a single surface-mounted wireless on-road sensor in a sensor array is functional due to the surface-mounted wireless on-road sensor becoming detached from the ground surface or otherwise failing.

9. transmitting various characteristics derived from the generated complete waveform by calculating an ensemble weighted average index for the complete waveform to create a wavelength signature; 7. The method of claim 6, comprising determining the reference point by calculating the center of gravity of the object from the waveform signature and the timestamp.

10. performing a DCT-II transform of a first predetermined number of samples from a first peak or valley found in the waveform to determine the waveform signature; 10. The method of claim 9, comprising generating small vectors by combining a first predetermined number of coefficients of a transform after compressing the magnitude.

11. 1. A system for traffic analysis, comprising: sensor arrays of surface-mounted wireless roadway sensors positioned within the surface of the ground, at least some of the sensor arrays each including at least three surface-mounted wireless roadway sensors spaced along a corresponding section of the surface of the ground; a receiver for receiving information from the sensor; an analyzer for analyzing the received information to determine mobile velocity information, the analyzer configured to compensate for a surface-mounted wireless along-road sensor that has become detached from the ground or is otherwise malfunctioning.

12. The system of claim 11 , wherein each sensor is configured to be substantially independent of the placement of the sensor within the sensor array.

13. The system of claim 11 , wherein the analyzer is configured to use a combination of sensor measurements in each array to improve accuracy.

14. The system of claim 11 , wherein the analyzer is configured to account for imprecise measurements of physical spacing between the sensors in the array.

15. 12. The system of claim 11, including a notifier for proactively issuing alerts to limit the number of surface-mounted wireless roadway sensors that become detached from the ground or are otherwise malfunctioning.

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