Patent Description:
Intelligent Transportation Systems (ITSs) are systems in which a plurality of devices communicate to allow for the transportation system to make better informed decisions with regard to transportation and traffic management, as well as allowing for safer and more coordinated decision-making. ITS system components may be provided within vehicles, as part of the fixed infrastructure such as on road verges, on bridges or at intersections, and for other users of the transportation system including pedestrians or bicyclists.

An ITS station is any entity that may provide ITS communications, including vehicles, infrastructure components, mobile devices, among other options. Such ITS communications currently provide information regarding the vehicle, its direction of travel, the size of the vehicle, among other similar information.

However, with regard to total vehicle length, a tractor unit (i.e. a towing vehicle) may not know the length or parameters of the trailer that is being towed. While ITS capable trailers may, in the future, have the capability to transmit their own ITS messaging, for the foreseeable future ITS systems will not be deployed on trailers, and once deployed there will be many legacy trailers within the transportation system. In addition, whilst some trailers may be able to convey their dimensions over a wired bus between the tractor and trailer this facility will not always exist. Such trailers that do not have these capabilities may be considered dumb trailers. Furthermore, an ITS equipped tractor unit may frequently connect to different types and dimensions of dumb trailers, and the complete tractor and trailer unit may be sending ITS messaging with inaccurate vehicle dimensions only based on the tractor unit dimensions. Inaccurate vehicle size information will adversely impact safety applications.

<CIT> relates to a controller and a method for determining vehicle length in a road train. Each controller may transmit a vehicle length and GPS coordinates in a specified wireless message format. The towing vehicle controller receives a first wireless message from the towed vehicle controller. The wireless message includes at least one of a speed of the towed vehicle, a length of the towed vehicle and GPS coordinates of the towed vehicle. The towing vehicle controller determines if the towed vehicle transmitting the message is coupled to the towed vehicle and then adds the length of the towed vehicle to the length of the towing vehicle to attain an overall length of the road train.

<CIT> relates to systems and methods for enabling vehicles to closely follow one another safely using automatic or partially automatic control.

The present disclosure provides a method at a first computing device within an Intelligent Transportation System for vehicle length reporting, according to appended claim <NUM>.

The present disclosure further provides a first computing device within an Intelligent Transportation System for vehicle length reporting, according to appended claim <NUM>.

The present disclosure further provides a computer readable medium for storing instruction code which, when executed by a processor of a first computing device within an Intelligent Transportation System for vehicle length reporting according to appended claim <NUM>.

In accordance with the embodiments described below, methods and systems for providing total vehicle or platoon length are provided.

Reference is now made to <FIG>. In the embodiment of <FIG>, example truck <NUM> having a trailer <NUM> and tractor <NUM> is shown. In one embodiment, a tag or computing device may be mounted on the back of the trailer. For example, in one embodiment the computing device may be mounted on the back door, or close to the top of the back door or on the rear side wall near the back door of the truck trailer <NUM>. This is shown, for example, with asset tracking device <NUM> in the embodiment of <FIG>.

The location of asset tracking device <NUM> near the rear of the trailer is however only one option for asset tracking. In some embodiments it may be useful to have a plurality of such asset tracking devices within the trailer <NUM>.

The asset tracking devices within trailer <NUM> may be used alone in some embodiments or may be combined into sets of two or more asset tracking devices and/or external sensors for asset tracking.

Further, in the embodiments of the present disclosure, a trailer <NUM> is merely used as an example. In other cases, the asset tracking device may be associated with a container capable of being loaded onto a trailer. Thus the use of the term trailer will include containers that are removable from a trailer bed.

One asset tracking device for a vehicle or container is shown with regard to <FIG>. The asset tracking device of <FIG> is however merely an example and other sensing devices could equally be used in accordance with the embodiments of the present disclosure.

Reference is now made to <FIG>, which shows an example asset tracking device <NUM>. Asset tracking device <NUM> can be any computing device or network node. Such sensor apparatus or network node may include any type of electronic device, including but not limited to, mobile devices such as smartphones or cellular telephones. Examples can further include fixed or mobile devices, such as internet of things (IoT) devices, endpoints, home automation devices, medical equipment in hospital or home environments, inventory tracking devices, environmental monitoring devices, energy management devices, infrastructure management devices, vehicles or devices for vehicles, fixed electronic devices, among others.

Asset tracking device <NUM> comprises a processor <NUM> and at least one communications subsystem <NUM>, where the processor <NUM> and communications subsystem <NUM> cooperate to perform the methods of the embodiments described herein. Communications subsystem <NUM> may, in some embodiments, comprise multiple subsystems, for example for different radio technologies.

Communications subsystem <NUM> allows asset tracking device <NUM> to communicate with other devices or network elements. Communications subsystem <NUM> may use one or more of a variety of communications types, including but not limited to cellular, satellite, Bluetooth™, Bluetooth™ Low Energy, Wi-Fi, wireless local area network (WLAN), sub-giga hertz radios, near field communications (NFC), IEEE <NUM>, wired connections such as Ethernet or fiber, among other options.

As such, a communications subsystem <NUM> for wireless communications will typically have one or more receivers and transmitters, as well as associated components such as one or more antenna elements, local oscillators (LOs), and may include a processing module such as a digital signal processor (DSP) or System on Chip (SOC). As will be apparent to those skilled in the field of communications, the particular design of the communication subsystem <NUM> will be dependent upon the communication network or communication technology on which the sensor apparatus is intended to operate.

Processor <NUM> generally controls the overall operation of the asset tracking device <NUM> and is configured to execute programmable logic, which may be stored, along with data, using memory <NUM>. Memory <NUM> can be any tangible, non-transitory computer readable storage medium, including DRAM, Flash, optical (e.g., CD, DVD, etc.), magnetic (e.g., tape), flash drive, hard drive, or other memory known in the art.

Alternatively, or in addition to memory <NUM>, asset tracking device <NUM> may access data or programmable logic from an external storage medium (not shown), for example through communications subsystem <NUM>.

In the embodiment of <FIG>, asset tracking device <NUM> may utilize a plurality of sensors, which may either be part of asset tracking device <NUM> in some embodiments or may communicate with asset tracking device <NUM> in other embodiments. For sensors within asset tracking device <NUM>, processor <NUM> may receive input from a sensor subsystem <NUM>.

Examples of sensors in the embodiment of <FIG> include a positioning sensor <NUM>, a vibration sensor <NUM>, a temperature sensor <NUM>, one or more image sensors / cameras <NUM>, accelerometer <NUM>, light sensors <NUM>, gyroscopic sensors <NUM>, a door sensor <NUM>, and other sensors <NUM>. Other sensors may be any sensor that is capable of reading or obtaining data that may be useful for the asset tracking device <NUM>. However, the sensors shown in the embodiment of <FIG> are merely examples, and in other embodiments, different sensors or a subset of sensors shown in <FIG> may be used. For example, in some cases the only sensor may be a position sensor.

For example, the position sensor may include a Global Navigation Satellite System (GNSS) receiver, for example a Global Positioning System (GPS) receiver (e.g. in the form of a chip or chipset) for receiving GNSS radio signals transmitted from one or more orbiting GNSS satellites. Although the present disclosure refers expressly to the Global Positioning System, it should be understood that this term and its abbreviation "GPS" are being used expansively to include any GNSS or satellite-based navigation-signal broadcast system, and would therefore include other systems used around the world including the Beidou (COMPASS) system being developed by China, the multi-national Galileo system being developed by the European Union, in collaboration with China, Israel, India, Morocco, Saudi Arabia and South Korea, Russia's GLONASS system, India's proposed Regional Navigational Satellite System (IRNSS), and Japan's proposed QZSS regional system, among others.

Communications between the various elements of asset tracking device <NUM> may be through an internal bus <NUM> in one embodiment. However, other forms of communication are possible.

Asset tracking device <NUM> may be affixed to any fixed or portable platform. For example, asset tracking device <NUM> may be affixed to shipping containers or truck trailers in one embodiment, as for example described above with regard to <FIG>.

Such an asset tracking device <NUM> may be a power limited device. For example, asset tracking device <NUM> could be a battery-operated device that can be affixed to a shipping container or trailer in some embodiments. Other limited power sources could include any limited power supply, such as a small generator or dynamo, a fuel cell, solar power, energy harvesting, among other options.

In other embodiments, asset tracking device <NUM> may utilize external power, for example from the battery or power system of a tractor pulling the trailer, via a wiring harness connected to a <NUM>-pin plug, from a land power source for example on a plugged-in recreational vehicle or from a building power supply, among other options. Thus, the asset tracking device <NUM> may also be connected to a power cord that receives its power from a power source.

External power may further allow for recharging of batteries to allow the asset tracking device <NUM> to then operate in a power limited mode again. Recharging methods may also include other power sources, such as, but not limited to, solar, electromagnetic, acoustic or vibration charging.

The asset tracking device from <FIG> may be used in a variety of environments. One example environment in which the asset tracking device may be used is shown with regard to <FIG>.

Referring to <FIG>, three asset tracking devices, namely asset tracking device <NUM>, asset tracking device <NUM>, and asset tracking device <NUM> are provided.

In the example of <FIG>, asset tracking device <NUM> may communicate through a cellular base station <NUM> or through an access point <NUM>. Access point <NUM> may be any wireless communication access point, including, but not limited to a wireless access network such as Wi-Fi.

Further, in some embodiments, asset tracking device <NUM> could communicate through a wired access point such as Ethernet or fiber, among other options.

The communication may then proceed over a wide area network such as Internet <NUM> and proceed to servers <NUM> or <NUM>.

Similarly, asset tracking device <NUM> and asset tracking device <NUM> may communicate with servers <NUM> or server <NUM> through one or both of the base station <NUM> or access point <NUM>, among other options for such communication.

In other embodiments, any one of asset tracking devices <NUM>, <NUM> or <NUM> may communicate through satellite communication technology. This, for example, may be useful if the asset tracking device is travelling to areas that are outside of cellular coverage or access point coverage.

In other embodiments, asset tracking device <NUM> may be out of range of access point <NUM> and may communicate with asset tracking device <NUM> to allow asset tracking device <NUM> to act as a relay for communications.

Communication between asset tracking device <NUM> and server <NUM> may be one directional or bidirectional. Thus, in one embodiment asset tracking device <NUM> may provide information to server <NUM> but server <NUM> does not respond. In other cases, server <NUM> may issue commands to asset tracking device <NUM> but data may be stored internally on asset tracking device <NUM> until the asset tracking device arrives at a particular location, possibly during a particular time window. In other cases, two-way communication may exist between asset tracking device <NUM> and server <NUM>.

A server, central server, processing service, endpoint, Uniform Resource Identifier (URI), Uniform Resource Locator (URL), back-end, and/or processing system may be used interchangeably in the descriptions herein. The server functionality typically represents data processing/reporting that are not performed at a location that is closely tied to the location of asset tracking devices <NUM>, <NUM>, <NUM>, etc. For example, the server may be located essentially anywhere so long as it has network access to communicate with asset tracking devices <NUM>, <NUM>, <NUM>, etc..

Server <NUM> may, for example, be a fleet management centralized monitoring station. In this case, server <NUM> may receive information from an asset tracking device associated with various trailers or cargo containers, providing information such as the location of such cargo containers, the temperature within such cargo containers, any unusual events including sudden decelerations, temperature warnings when the temperature is either too high or too low, cargo loading within the trailer, the mass of the trailer, among other data. The server <NUM> may compile such information and store it for future reference. Further, in some cases server <NUM> may include an association between a tractor and a trailer, where the association is either a current pairing or a future time or geographic location pairing.

Other examples of functionality for server <NUM> are possible.

In the embodiment of <FIG>, servers <NUM> and <NUM> may further have access to third-party information or information from other servers within the network. For example, a data services provider <NUM> may provide information to server <NUM>. Similarly, a data repository or database <NUM> may also provide information to server <NUM>.

For example, data services provider <NUM> may be a subscription-based service used by server <NUM> to obtain current road and weather conditions or may be an inventory control system in some cases.

Data repository or database <NUM> may for example provide information such as image data associated with a particular location, aerial maps, detailed street maps, or other such information.

The types of information provided by data service provider <NUM> or the data repository or database <NUM> is not limited to the above examples and the information provided could be any data useful to server <NUM>.

In some embodiments, information from data service provider <NUM> or the data repository from database <NUM> can be provided to one or more of asset tracking devices <NUM>, <NUM>, or <NUM> for processing at those asset tracking devices.

Intelligent Transportation System software and communication systems are designed to, for example, enhance road safety and road traffic efficiency. Such systems include vehicle to/from vehicle (V2V) communications, vehicle to/from infrastructure (V2I) communications, vehicle to/from network (V2N) communications, vehicle to/from the pedestrian or portable (V2P) communications, and vehicle to network to vehicle (V2N2V). The communications from a vehicle to/from any of the above may be generally referred to as V2X.

Further, other elements in a system may communicate with each other. Thus, systems may include portable to/from infrastructure (P2I) communications, infrastructure to infrastructure (I2I) communications, portable to portable (P2P) communications (also known as peer to peer communications), among others. As used herein, V2X thus includes any communication between an ITS station and another ITS station, where the station may be associated with a vehicle, road side unit, network element, pedestrian, cyclist, animal, among other options. For example, vehicles on a highway may communicate with each other, allowing a first vehicle to send a message to one or more other vehicles to indicate that it is braking, thereby allowing vehicles to follow each other more closely.

Communications between elements of an ITS may further allow for potential collision detection and allow a vehicle with such a device to take action to avoid a collision, such as braking or swerving. For example, an active safety system on a vehicle may take input from sensors such as cameras, RADAR, LIDAR, and V2X, and may act on them by steering or braking, overriding or augmenting the actions of the human driver or facilitating autonomous driving where a human is not involved at all. Another type of advanced driver assistance system (ADAS) is a passive safety system that provides warning signals to a human driver to take actions. Both active and passive safety ADAS systems may take input from V2X and ITS systems.

In other cases, fixed infrastructure may give an alert to approaching vehicles that they are about to enter a dangerous intersection or alert vehicles to other vehicles or pedestrians approaching the intersection. This alert can include the state of signals at the intersection (signal phase and timing (SPaT)) as well as position of vehicles or pedestrians or hazards in the intersection. Other examples of ITS communications would be known to those skilled in the art.

Reference is now made to <FIG>, which shows one example of an ITS station, as described in the European Telecommunications Standards Institute (ETSI) European Standard (EN) <NUM>, "Intelligent Transport Systems (ITS); communications architecture", as for example provided for in version <NUM>. <NUM>, September <NUM>.

In the embodiment of <FIG>, a vehicle <NUM> includes a vehicle ITS sub-system <NUM>. For example, such subsystem may be found within tractor <NUM>, as shown by reference numeral <NUM> in the embodiment of <FIG>. Vehicle ITS sub-system <NUM> may, in some cases, communicate with an in-vehicle network <NUM>. The in-vehicle network <NUM> may receive inputs from various electronic control unit (ECUs) <NUM> or <NUM> in the environment of <FIG>.

Vehicle ITS sub-system <NUM> may include a vehicle ITS gateway <NUM> which provides functionality to connect to the in-vehicle network <NUM>.

Vehicle ITS sub-system <NUM> may further have an ITS-S host <NUM> which contains ITS applications and functionality needed for such ITS applications.

Further, an ITS-S router <NUM> provides the functionality to interconnect different ITS protocol stacks, for example at layer <NUM>. ITS-S router <NUM> may be capable of converting protocols, for example for the ITS-S host <NUM>.

Further, the ITS system of <FIG> may include a personal ITS sub-system <NUM>, which may provide application and communication functionalities of ITS communications (ITSC) in handheld or portable devices, such as personal digital assistants (PDAs), mobile phones, user equipment, among other such devices.

A further component of the ITS system shown in the example of <FIG> includes a roadside ITS sub-system <NUM>, which may contain roadside ITS stations which may be deployed on bridges, traffic lights, among other options.

The roadside ITS sub-system <NUM> includes a roadside ITS station <NUM> which includes a roadside ITS gateway <NUM>. Such gateway may connect the roadside ITS station <NUM> with one or more roadside networks <NUM>.

A roadside ITS station <NUM> may further include an ITS-S host <NUM> which may contain ITS-S applications and the functionalities needed for such applications.

The roadside ITS station <NUM> may further include an ITS-S router <NUM>, which provides the interconnection of different ITS protocol stacks, for example at layer <NUM>.

The roadside ITS station <NUM> may further include an ITS-S border router <NUM>, which may provide for one or both of the interconnection of two protocol stacks and the interconnection to an external network.

A further component of the ITS system in the example of <FIG> includes a central ITS sub-system <NUM> which includes a central ITS station internal network <NUM>.

Central ITS station internal network <NUM> includes a central ITS gateway <NUM>, a central ITS-S host <NUM> and an ITS-S border router <NUM>. Central ITS gateway <NUM>, central ITS-S host <NUM> and ITS-S border router <NUM> have similar functionality to the Roadside ITS gateway <NUM>, ITS-S host <NUM> and ITS-S border router <NUM> of the roadside ITS station <NUM>.

Communications between the various components may occur through an ITS peer-to-peer communications network or via network infrastructure <NUM>.

From <FIG> above, V2X communications may be used for both road safety and for improving efficiency of road transportation, including movement of vehicles, reduced fuel consumption, among other factors.

V2X messages are defined by the European Telecommunications Standards Institute (ETSI) fall into two categories, namely Cooperative Awareness Message (CAM) and Decentralized Environmental Notification Message (DENM). A CAM message is a periodic, time triggered message that may provide status information to neighboring ITS stations. The broadcast is typically over a single hop and the status information may include a station type, position, speed, heading, among other options. Optional fields in a CAM message may include information to indicate whether the ITS station is associated with roadworks, rescue vehicles, or a vehicle transporting dangerous goods, among other such information.

Typically, a CAM message is transmitted between <NUM> and <NUM> times per second.

A DENM message is an event triggered message that is sent only when a trigger condition is met. For example, such trigger may be a road hazard or an abnormal traffic condition. A DENM message is broadcast to an assigned relevance area via geo-networking. It may be transported over several wireless hops and event information may include details about the causing event, detection time, event position, event speed, heading, among other factors. DENM messages may be sent, for example, up to <NUM> times per second over a duration of several seconds.

Similar concepts apply to the Dedicated Short-Range Communications (DSRC)/Wireless Access in Vehicular Environments (WAVE) system in which a Basic Safety Message (BSM) is specified instead of the CAM/DENM messaging from ETSI.

For ETSI, the Cooperative Awareness basic service stores at least the following information for the CAM originated ITS-S operation: CAM generation time; ITS-S position as included in the CAM; ITS-S speed as included in the CAM; ITS-S heading as included in the CAM.

CAM messages that are received at an asset tracking device generally are in a particular format. For example, a CAM message includes a header, which is for example described in Appendix B. <NUM> in ETSI EN <NUM><NUM>-<NUM> V1. <NUM>, September <NUM>. <NUM> header is described in Table <NUM> below.

The station type is described in CAM messages in Appendix B. <NUM>, which is shown in Table <NUM> below.

The reference position is described in CAM messages in Appendix B. <NUM>, which is shown in Table <NUM> below.

In the messaging of Table <NUM> above, when the tractor gives its position it will be that of the very front of the tractor. This reported geolocation reference position is the location of the antenna plus an offset, which may be configured at the time the vehicle is manufactured or the system is installed, among other options. In particular, according to Table <NUM>, a position may be included when there is a <NUM>% confidence level that the true location of the middle of the front of the tractor is within a given ellipse drawn around the pinpoint broadcast location. As defined, for example in <NPL>, a "confidence level" is the probability of the accumulated error of a measurement being within the stated range of uncertainty of measurement. Here the stated range is <NUM>%. A <NUM>% confidence level is further defined in ETSI TBR <NUM>, March <NUM> as <NUM> times the total standard deviation, based on the Student t factor, where the Student t factor is a continuous probability distribution that arises when estimating the mean of a normally distributed population in situations where the sample size is small and the population standard deviation is unknown.

When an asset tracking device is at the back of a trailer then the computation of combined tractor/trailer length can be done by subtracting the position of the front of the tractor from the position of the back of the trailer when it is determined that the tractor and trailer are aligned in the same direction. For example, reference is now made to <FIG>, which shows a diagram from section <NUM> of <NPL>).

In accordance with the embodiment of <FIG>, a truck or tractor <NUM> includes a GNSS antenna position <NUM>. However, the reported geolocation reference position <NUM> corresponds with the front side, relative to a driving direction, middle point of a rectangular box <NUM> enclosing the truck.

The heading of the sending vehicle found in CAM messages is described in Appendix B. <NUM> and is shown in Table <NUM> below.

The speed of the sending vehicle found in CAM messages is described in Appendix B. <NUM> and is shown in Table <NUM> below.

The vehicle length of the sending vehicle is found in CAM messages and is described Appendix B. <NUM>, as shown in Table <NUM> below.

The length of the vehicle may, in some cases, be determined and reported based on a geolocation reference position for the vehicle, as for example described in Section <NUM> of<NPL>.

The vehicle width of the sending vehicle in CAM messages is described in Appendix B. <NUM>, as shown in Table <NUM> below.

From Tables <NUM> to <NUM> above, various information with regard to a vehicle may be determined based on the CAM messages transmitted from such vehicle.

In accordance with the embodiments of the present disclosure, an asset tracking device connected to a trailer can be used as part of a length calculation of the tractor and trailer combination, thus allowing for more accurate V2X reporting.

In a first embodiment, an ITS tractor unit may provide V2X messages. The asset tracking device on the trailer may identify the tractor unit that the trailer is attached to and may then determine its own location.

The asset tracking device may report its position to the ITS tractor unit, which may then use the position to calculate the trailer length and therefore the entire length of the tractor and trailer unit. The ITS tractor unit may thereafter use the corrected length in V2X reporting.

The asset tracking device in this case would be part of the ITS system through its capability to receive V2X messages. Further, in some cases the asset tracking device could also transmit V2X messages.

In particular, reference is now made to <FIG>. In the embodiment of <FIG>, a tractor ITS unit <NUM> communicates with a trailer asset tracking device <NUM>. As indicated above, the trailer asset tracking device <NUM> and the tractor ITS unit <NUM> may communicate with one or more network servers <NUM>.

In accordance with the embodiments described herein, in some cases one or more network servers communicate with the asset tracking device <NUM>. The one or more network servers that communicate with trailer ITS unit <NUM> and asset tracking device <NUM> may be the same server or different servers. If different, the servers may communicate, either directly or indirectly with each other to allow communication between the trailer asset tracking device <NUM> and the tractor ITS unit <NUM>.

The tractor ITS unit <NUM> transmits V2X messages <NUM> pursuant to ITS requirements. Such V2X messages <NUM> generally include a vehicle length, heading, and speed for the vehicle, among other information.

The trailer asset tracking device <NUM> may rely on a trigger condition <NUM> to begin a process to transmit its length. For example, a trigger condition may be that the trailer has been stationary for a threshold time period. In other cases, the trigger may be the detection of movement after the trailer has been stationary for a certain amount of time. In other cases, the trigger may be the entering or exiting of the geofenced area. For example, the geofenced area may indicate a trailer yard where the trailer is loaded, unloaded, or stored, which may indicate that the trailer could be unhooked and hooked to a different tractor.

In other cases the trigger at block <NUM> may be that the V2X message provides that the vehicle LengthConfidenceIndication indicates that the tractor doesn't know the length of the trailer.

Other examples of trigger conditions would be apparent to those skilled in the art having regard to the present disclosure.

Once the trigger condition has been met, the process proceeds to block <NUM> in which the trailer asset tracking device identifies the tractor that it is connected to. This could be done in several ways.

In a first embodiment, the tractor unit may be identified at the asset tracking device through manual input. For example, an administration may input the association at a central database. Thereafter, the tractor unit connected to the trailer may be identified through provisioning by the asset tracking service. Such provisioning may, for example, provide an identifier or set of identifiers for the tractor unit towing the trailer to the asset tracking device.

In other cases, the tractor ITS unit <NUM> may communicate directly with the asset tracking device <NUM>.

In other cases, the asset tracking device may activate its ITS receiver, for example upon matching the trigger condition. The ITS receiver on the asset tracking device obtains an ITS message (for example a BSM/CAM) from the strongest source. In many cases, the strongest source may be from the vehicle that is associated with the asset tracking device. However, in other cases, the strongest signal may be from a vehicle that is trailing the vehicle associated with the device, from a roadside unit, or from other devices. In this case, the connected tractor may be identified over a period of time where the strongest signal or a consistently strong signal originates from the tractor, and whereas other vehicles or Road side units may move away from the trailer.

In some cases, in addition to position information, heading information, speed information, station type information, among other information may be obtained from the BSM/CAM message. This information could further be used to identify the tractor based on readings obtained at the asset tracking device.

For example, a compass on the asset tracking device may be compared with the direction information found in the received V2X message.

In other cases, rather than a compass, the asset tracking device may filter out messages in which the acceleration is different or inconsistent. This may be achieved by use of an accelerometer sensor in the asset tracking device and by comparison of the acceleration computed using this sensor with the differential of velocity obtained from multiple V2X messages having the same certificate identifier.

In some cases, the asset tracking device may obtain a location, direction and/or speed using the GPS location from a GPS receiver. The comparison of the position fix/direction/speed from the GPS location with the ITS message may be used for a variety of purposes. In one case, it may help to associate the ITS station that is pulling the trailer with the asset tracking device. The asset tracking device can improve its confidence that, or even infer that, messages containing a certain certificate identifier are produced by a tractor ITS unit vehicle towing the trailer if the absolute difference in distance between the GPS position of the asset tracking device and the position reported by the ITS station remains the same over multiple observation periods, or if the heading reported in the CAM/BSM message is the same as the heading that the asset tracking device records, or if the velocity reported in in the CAM/BSM message is the same as the velocity that the asset tracking device records, or if the station type in the CAM/BSM message corresponds to the expected station type of a towing vehicle where that expected station type is pre-stored in the asset tracking device. Confidence that the source of CAM/BSM messages with a given certificate identifier are coming from a tractor unit, with the above methods, increases if the asset tracking device is moving or as the count of the number of times that the same correlations are observed increases.

In other cases, multiple BSM/CAM messages may be received from multiple sources and a search made amongst these messages for the certificate identifier that has been received most frequently in the past, and which is therefore most likely to have been included in a message generated by a tractor ITS unit.

Based on the above, the asset tracking device on the trailer first may find the trailer is attached to a tractor (producer of V2X messages) and then that the identity of this associated tractor is recorded (could be through pseudonyms, or any other hard coded identity provided in the V2X message). After this, the asset tracking device may provide this identity either to asset tracking server, so asset tracking server can forward the information to the correct tractor. In other cases, the asset tracking device may send a direct mode message to the tractor with an identifier, and the appropriate tractor knows whether or not the message is meant to be interpreted by itself or by another tractor.

In some cases, an ITS station may have a plurality of certificates. For example, the use of a plurality of certificates has been proposed in order to protect privacy and prevent an ITS station from being tracked. In this case, a vehicle may be pre-provisioned with a plurality of certificates, which may then be cycled through when providing ITS messages.

In order to help identify an ITS station associated with an asset tracking device, the asset tracking device may in some cases store a list of the certificate identifiers for the tractor unit.

The list of certificate identifiers for the tractor unit may, in some cases, be provisioned to the asset tracking device. In this case, the asset tracking device may receive and populate its list with the received information and may thereafter use this information to identify BSM/CAM messages from the tractor unit associated with the asset tracking device.

In other cases, the asset tracking device may build a list of certificate identifiers observed over time and may then reference this list to find the V2X signal from the tractor ITS unit.

Once the tractor ITS unit for the tractor towing the trailer is identified at block <NUM>, the process proceeds to block <NUM> in which the asset tracking device may determine its GPS location. The determination of the GPS location may be done periodically, for example every <NUM>, and then reported to the tractor ITS unit <NUM>. For example, the reporting may be done directly between the trailer asset tracking device <NUM> in the tractor ITS unit <NUM>, as shown by message <NUM>. This direct communication may, for example, utilize an IP connection between the two units. In other cases, the reporting may be done by sending a V2X signal. In some cases, direct communication will introduce a lag and therefore the reported position may include a timestamp for the reported position which may then be compared with positioning taken at the tractor ITS unit at the same time. In practice, the "same time" would be within a threshold time period between the two readings, for example <NUM> or less.

However, if direct communication is not possible, then the position may be reported utilizing network service <NUM>. For example, the GPS location may be reported in message <NUM> to network servers <NUM> which may then provide the reported position in message <NUM> to the tractor ITS unit <NUM>.

Message <NUM> or message <NUM> could also include an indication that the location measurement is made from an asset tracking device that is at the very back of the trailer. Futher, the indication may be provided with <NUM>% confidence level that the true location of the middle of the back of the trailer is within a given ellipse drawn around the pinpoint broadcast location. In other cases, the asset tracking device could perform an adjustment in reported location so that position corresponds to the back of the trailer even if the asset tracking device is not mounted on the very back. In particular, the reported geolocation reference position is the location of the GNSS antenna plus an offset, which may be configured at the time the system is installed, among other options.

Further message <NUM> or message <NUM> could also include the width of the trailer (if available), and an indication that the trailer is of symmetrical proportions about the towing point (if available). The location measurement might also need to include some confidence ellipse, pursuant to ETSI-ITS specifications.

As will be appreciated by those skilled in the art, the reporting through a network service will introduce a lag and therefore the reported position will typically include a timestamp for the reported position which may then be compared with positioning taken at the tractor ITS unit at the same time. In practice, the "same time" would be within a threshold time period between the two readings, for example <NUM> or less.

Specifically, the tractor ITS unit <NUM> may determine its position at block <NUM> and store such position with time stamps. In some cases, the GPS location at the tractor ITS unit and the GPS location at the asset tracking device may be compared based on the timing of the two GPS position fixes. In one method the asset tracking device could determine from multiple V2X messages <NUM>, absolute times at which the tractor ITS unit is making its position fixes, and also the period with which repeated position fixes are being reported in V2X messages <NUM>. This enables the asset tracking device to determine a future time, for example, that occurs in a few reporting periods hence, at which the asset tracking device should make its position fix, such that the making of the asset tracking device's position fix is synchronised with the expected time that the ITS tractor unit will be making its position fix. In another method the making of position fixes in the tractor's ITS unit and in the asset tracking device are not synchronised, however, the asset tracking device makes multiple periodic measurements and an interpolation is performed either at the asset tracking device or at the tractor ITS unit to determine the position that the asset tracking device was expected to have been in at the time instant corresponding to that at which the location fix was made by the tractor ITS unit. In other cases, the two position fixes may be taken while the vehicle is stationary, in which case the timing between the GPS position fixes on the tractor ITS unit and the trailer do not need to be strictly coordinated. For example, when hooking together, an accelerometer or bump sensor within the trailer may detect the bump from the hookup and start reporting the position of the trailer. Using these methods, providing that the tractor and trailer are spatially arranged in a straight line then the two location fixes, which either actually were made at the same time or which were computationally determined to have occurred at the same time, can be vector subtracted from one another so that the length of the vector can be used to give the length of the vehicle.

In some cases, however, the tractor and the trailer may not be positioned linearly when being connected. For example, if the tractor is at an angle to the trailer when being connected, the distance between the asset tracking device and the tractor ITS unit may be different than when the tractor starts pulling the trailer in a straight direction. In this case, a plurality of measurements may be taken and used to find the most common length or the longest length.

In some cases, the vehicle length may be calculated when the vehicle stops, for example at a stop sign or a traffic light.

Further, in some cases the asset tracking device or the trailer ITS unit may have velocity vectors which may indicate that that the vehicle is turning a corner. These velocity vectors made indicate to the asset tracking device or ITS unit not to perform calculations until the vehicle is straightened out.

Other parameters for when to take readings or when to avoid readings will be known by those skilled in the art having regard to the above.

Such calculation of the length may be done, for example, in block <NUM> and may involve using one or a plurality of differences between the position at the tractor ITS unit <NUM> and trailer asset tracking device <NUM>.

In some cases, once the length has been calculated, in order to save battery power on the asset tracking device, the tractor ITS unit <NUM> may signal the asset tracking device <NUM> to enter a sleep mode. In this case, the sleep mode turns off an ITS unit at the asset tracking device. If direct communication exists between tractor ITS unit <NUM> and trailer asset tracking device <NUM>, the signaling to enter the sleep mode may be done directly, as for example shown with message <NUM>. In other cases, the signaling to enter the sleep mode may be done through one or more network servers <NUM>, as for example shown with messages <NUM> and <NUM>.

If an ITS unit at the asset tracking device <NUM> enters a sleep mode, the tractor ITS unit <NUM> or network server <NUM> may, in some cases, signal at a future time to awaken to perform the process of <FIG> again to verify the vehicle length. In other cases, a trigger at the asset tracking device <NUM> may occasionally wake the ITS radio at the asset tracking device to perform the process of <FIG> again. For example, such trigger may be a timer, or may be based on sensor readings at the asset tracking device <NUM>.

While the embodiment of <FIG> includes an identification of the tractor connected to the trailer asset tracking device at block <NUM>, in some cases this step may be omitted. For example, if the position is being reported through network service, the network service may know the association between the tractor ITS unit and the trailer asset tracking device. In this case, it may not be necessary to identify the connected tractor at the asset tracking device but rather the association between the tractor and the trailer may be done through knowledge at the network servers.

Based on the above, the embodiment of <FIG> includes an asset tracking device reporting its position and the tractor ITS unit calculating a total vehicle length based on the reported position of the asset tracking device. Once the vehicle length is calculated, the tractor ITS unit may then use that length in future V2X messages.

In a further embodiment, if a trailer is connected to a tractor, the asset tracking device in the trailer receives V2X messages from the ITS unit within the tractor. The asset tracking device can then determine its own relative location to that of the tractor unit and calculate whether the broadcast message "vehicle length" is correct or not. If not, the asset tracking device may facilitate a correction. Conversely, if the transmitted ITS message contains the correct vehicle length, the asset tracking device may thereafter deactivate its V2X capability.

Again, the asset tracking device in this case would be part of the ITS system through its capability to receive V2X messages. Further, in some cases the asset tracking device could also transmit V2X messages.

In particular, reference is now made to <FIG>. In the embodiment of <FIG>, a tractor ITS unit <NUM> may communicate, either directly or indirectly with a trailer asset tracking device <NUM>. Indirect communication may involve one or a plurality of network servers <NUM>.

A tractor ITS unit <NUM> may be transmitting V2X messages, as shown by message <NUM> in the embodiment of <FIG>.

Upon a trigger event <NUM>, the trailer asset tracking device <NUM> may begin to listen for the V2X messages <NUM>. Either utilizing information within the V2X message <NUM> or through some other means as described above with regard to block <NUM>, the asset tracking device <NUM> may identify the trailer that it is connected with, as shown at block <NUM>. For example, the tractor may be identified through a pseudonym identifier or permanent identifier if available, for example as provisioned on the asset tracking device <NUM> or received through a connection with a network server. In other cases, orientation and signal strength of the V2X signal may be used to identify the tractor. In other cases, other identifiers within parameters provided in the V2X message, such as speed, acceleration, location, among others, may show a correlation over time with sensor measurements at the asset tracking device <NUM>.

The process at the asset tracking device <NUM> then proceeds to block <NUM> in which the relative location of the asset tracking device with regard to the tractor is determined. This may be done in several ways. In one embodiment, the timing of the positioning updates may be synchronized between the asset and the tractor. For example, if the V2X message includes a timestamp at which the location measurement was made, then the asset tracking device can then take a position fix and compare its position at a similar timestamp to that associated with the position reported in the V2X message. The similar timestamp may be within a threshold time difference between the time of position fix and the time reported in the V2X message. In one method the asset tracking device could determine from multiple V2X messages <NUM>, absolute times at which the tractor ITS unit is making its position fixes, and also the period with which repeated position fixes are being reported in V2X messages <NUM>. This enables the asset tracking device to determine a future time, for example, that occurs in a few reporting periods hence, at which the asset tracking device should make its position fix, such that the making of the asset tracking device's position fix is synchronised with the expected time that the ITS tractor unit will be making its position fix.

In another method the making of position fixes in the tractor's ITS unit and in the asset tracking device are not synchronised, however, the asset tracking device makes multiple periodic measurements and an interpolation may be performed to determine the position that the asset tracking device was expected to have been in at the time instant corresponding to that at which the location fix was made by the tractor ITS unit.

In other cases, the position update may be taken while the vehicle is stationary. For example, the trigger at block <NUM> may be a bump sensor or an accelerometer indicating that the trailer has been connected to a tractor. At this point, the asset tracking device may take a position fix and compare the position with that reported in the V2X message being transmitted by the tractor ITS unit <NUM>.

In other cases, the position fix may be taken while, for example, the vehicle is stationary. For example, a vehicle leaving a trailer yard may encounter stop signs or traffic lights and the position fix may be taken while the vehicle is stopped at those stop signs or traffic lights.

In the cases where the vehicle is stationary, the timing between the GPS position fixes on the tractor ITS unit and the trailer do not need to be strictly coordinated.

Other ways to synchronize the timing for the position fix would be apparent to those skilled in the art having regard to the present disclosure.

Using these methods, providing that the tractor and trailer are spatially arranged in a straight line then the two location fixes, which either actually were made at the same time or which were computationally determined to have occurred at the same time, can be vector subtracted from one another so that the length of the vector can be used to give the length of the vehicle.

From block <NUM>, the process at the asset tracking device <NUM> proceeds to block <NUM> in which the relative location as determined at block <NUM> is compared against the reported length in the V2X message received from the tractor ITS unit <NUM>. The asset tracking device can, for example, determine its estimate of the length of the vehicle by determining the length of the vector between the position reported in the V2X message, which corresponds to the very front of the vehicle, and the time synchronized measurement of position determined at the asset tracking device, which corresponds to the very back of the trailer or container.

The process then proceeds to block <NUM> where a check is made to determine whether the reported length is correct. If yes, then the ITS receiver may proceed into a sleep state, shown at block <NUM>.

Conversely, if the reported length is not correct, then the asset tracking device <NUM> may attempt to correct the length reported by the tractor ITS unit <NUM>.

If a direct connection exists between the asset tracking device <NUM> and the tractor ITS unit <NUM>, then a communication between the asset tracking device <NUM> and tractor ITS unit <NUM> may be made to indicate the correct length, as shown by message <NUM>.

In other cases, message <NUM> may be sent as a V2X communication from the asset tracking device <NUM>. In this case, the tractor ITS unit <NUM> may receive the V2X message <NUM>, may associate the trailer with the tractor unit and therefore determine that a corrected length is being provided in V2X message <NUM>. In this case, the tractor ITS unit <NUM> may use a similar process to that described for block <NUM> to identify the correlation between the asset tracking device and the tractor ITS unit. The asset tracking device may also include within a V2X message a destination address for that V2X message, so that the tractor unit knows whether the length correction is intended for itself. This destination address could, for example comprise or be derived from any identifier that the tractor unit has itself been using in the past, for example a certificate pseudonym identifier or a Layer <NUM> identifier.

Alternatively, the length correction may be sent through network servers <NUM>. This is shown, for example with message <NUM> between the asset tracking device <NUM> and the network servers <NUM>. The network servers <NUM> may then provide the corrected length in message <NUM> to the tractor ITS unit <NUM>.

For example, the network servers <NUM> may include an asset tracking server associated with the asset tracking device <NUM>. Further, such asset tracking server may communicate with a V2X server that can communicate with tractor ITS unit <NUM>.

However other options with regard to servers are within the scope of the present disclosure.

After receiving either message <NUM> or <NUM>, the tractor ITS unit <NUM> may then start using the corrected vehicle length.

If an ITS unit at the asset tracking device <NUM> enters a sleep mode at block <NUM>, a trigger at the asset tracking device <NUM> may occasionally wake the ITS radio at the asset tracking device to perform the process of <FIG> again. For example, such trigger may be a timer, or may be based on sensor readings at the asset tracking device <NUM>. In other cases, a signal from the tractor ITS unit <NUM> or network server <NUM> may cause the ITS receiver at the asset tracking device <NUM> to wake up.

Therefore, in accordance with the embodiment of <FIG>, it is the asset tracking device <NUM> that determines whether the length reporting is correct or not, and if not, the asset tracking device <NUM> attempts to correct the reported length.

With all of the above techniques, the asset tracking device may take into account uncertainty in the location of the mid-front of the vehicle as provided by the tractor. In particular, as described in Table <NUM> above, uncertainty might be specified as a <NUM>% confidence level that the true location of the middle of the front of the tractor is within a given ellipse drawn around the pinpoint broadcast location. For example, if the asset tracking determines that the broadcast length is incorrect for any possible mid-front of vehicle position within this ellipse, then that would trigger the asset tracking device to provide a correction. Otherwise the asset tracking device would not provide a correction.

In a further embodiment, a server may have details of the association between the tractor and the trailer. In this case, an asset tracking device may inform an asset tracking server of a trigger condition being met. The asset tracking server may then perform a lookup of the trailer details associated with the particular asset and supply this to the tractor for use in ITS messaging.

For example, reference is now made to <FIG>. In the embodiment of <FIG>, a tractor ITS unit <NUM> is associated with a trailer asset tracking device <NUM>. One or more network servers <NUM> may communicate with each or both of tractor ITS unit <NUM> and trailer asset tracking device <NUM>.

The trailer asset tracking device <NUM> may monitor for a trigger condition at block <NUM>. For example, the trigger condition may be that the asset is moving. In other cases, the trigger condition may be the entering or leaving of a geofenced area. In other cases, the trigger condition may be a combination of a timer and an accelerometer reading. For example, if the trailer has been sitting idly longer than <NUM> minutes, and then starts moving, this may indicate the trigger condition. Other options for a trigger condition would be apparent to those in the art having regard to the present disclosure.

If a trigger condition is detected at block <NUM>, then a message <NUM> may be provided to a network server <NUM>. Message <NUM> may indicate that the trigger condition has been met and in addition there will be a means by which the server can associate the trailer's identity with the message that it has just received. This association could be achieved, for example, simply by the fact that the message <NUM> was received over an IP connection that has been previously assigned to the asset tracking device of known identity.

Upon receiving the trigger message <NUM>, the network server <NUM> may look up the trailer details at block <NUM> and determine the tractor associated with the trailer at block <NUM>. Once the association is made, then the network server <NUM> may provide a message <NUM> to the tractor ITS unit <NUM> indicating the length of the trailer or the length of the combined vehicle, or the position of the back of the trailer at a given point in time. Other parameters might also be included for example, the width, height or other dimensions of the trailer or container. As will be appreciated by those in the art, message <NUM> may proceed through a plurality of servers before being reported to tractor ITS unit <NUM>.

Once the tractor ITS unit <NUM> receives message <NUM>, it may then use the length that was provided when generating future ITS messages, as shown by block <NUM>.

In other cases, instead of waiting for a trigger message <NUM>, network server <NUM> may include an association between an asset and a tractor. When that association changes then the steps at block <NUM> and <NUM> may be performed and the new length of the trailer may be provided to tractor ITS unit <NUM>. For example, the configuration may be manually updated in an asset tracking system to associate a new trailer with the tractor.

In some cases, the updating may include a time at which the trailer is expected to be associated with that tractor. For example, the manual update may be a scheduling update for the tractor to pick up the trailer. In this case, the asset tracking system may know approximately when the tractor will pick up the trailer and convey this information. In other cases, the sending of the new association information may be delayed until the expected association time. In either case the position or length information is not used by the tractor unit in the generation of the V2X message until after the time at which the association between tractor and trailer is expected to, or is determined to have occurred. This determination may be made using a combination of determination that a coupling has occurred, where that coupling has occurred within a given time window of the a priori communicated expected time of coupling.

For example, reference is now made to <FIG>. In the embodiment of <FIG>, a network server <NUM> communicates with a tractor ITS unit <NUM>.

At block <NUM>, network server <NUM> finds a new association between a tractor and a trailer. The network server <NUM> may then provide a message <NUM> to the tractor ITS unit <NUM> to report the length of the trailer, or length of combined trailer and tractor, or position of back of trailer at a given point in time. As indicated above, message <NUM> may indicate a time that the expected association is supposed to happen or the sending a message <NUM> may be delayed until the association is expected to happen in some cases.

Once the tractor ITS unit <NUM> receives message <NUM>, it may then use the length in ITS messages, as shown by block <NUM>. If message <NUM> includes an expected time, then the use of the trailer length at block <NUM> may be delayed until such time. The position or length information is not used by the tractor unit in the generation of the V2X message until after the time at which the association between tractor and trailer is expected to, or is determined to have occurred. This determination may be made by the tractor unit using a combination of determination that a coupling event has occurred, where that coupling has occurred within a given time window of the a priori communicated expected time of coupling.

In some cases, a tractor may tow a plurality of trailers. For example, reference is now made to <FIG>. In the embodiment of <FIG>, a tractor <NUM> includes an ITS unit <NUM>.

The tractor <NUM> is towing a first trailer <NUM> having an asset tracking device <NUM>.

Further, a second trailer <NUM> is being towed behind trailer <NUM>. The second trailer <NUM> includes an asset tracking device <NUM>.

The vehicle length in this case should include the total length of the tractor and the two trailers.

Further, the use of ITS communications allows for a platooning. In particular, a platoon is a plurality of vehicles which may have a decreased distance between the vehicles to allow the vehicles to travel together for at least a portion of their journey. The ITS communications allow the following vehicles to know when a vehicle ahead of them is accelerating, breaking, turning, among other actions. The use of a platoon provides an efficient system to use road resources, potentially allow for fully autonomous vehicles, and may save fuel due to less air resistance for following vehicles, among other benefits.

V2X reporting provides the length of the entire platoon rather than the individual vehicle. For example, referencing <FIG>, a platoon <NUM> includes a lead vehicle <NUM> and an end vehicle <NUM>. The length reporting may need to include the length from the front of the tractor of lead vehicle <NUM> to the rear of the trailer of end vehicle <NUM>.

The embodiments of <FIG> above are adapted to include a conflict resolution mechanism to ignore lengths reported by intermediate trailers or vehicles.

In particular, utilizing the embodiment of <FIG>, tractor ITS unit <NUM> receives position reports in messages <NUM> or <NUM> for the two trailers behind the tractor. The determining the combined length at block <NUM> simply ignores the shorter length or closer position reported, and therefore use the longer length.

Similarly, in a platoon, the tractor ITS unit <NUM> may ignore the V2X messages from everything except for the end vehicle when making the length calculation at block <NUM>.

In the embodiment of <FIG>, if a plurality of trailers is being pulled by the tractor, each of the trailers would perform the calculations at blocks <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. In this case, each of the trailers provides a report to the tractor ITS unit <NUM>. For example, the report is found in messages <NUM> or <NUM>. In this case, if trailers are providing their estimates of the length of the platoon then the tractor ITS unit <NUM> may ignore the shorter lengths and use the longest length reported. Trailers are providing position estimates made at given time instants and the tractor unit <NUM> ignores positions that are the least far away and use only that position which is the furthest away. However, in this case, in order to avoid the middle trailer continually providing corrected length messaging, the tractor ITS unit <NUM> may signal to the trailer or asset tracking device <NUM> of the middle trailer to enter a sleep state. This may be done, for example, utilizing similar messaging to message <NUM> or messages <NUM> and <NUM> from the embodiment of <FIG>.

For the embodiment of <FIG> and <FIG>, the network servers <NUM> or <NUM> may determine that the association is to a plurality of trailers and in this case, may provide the combined length in messages <NUM> or <NUM>.

The above therefore provides for the correction of the reported length in ITS messaging to provide a more accurate "vehicle length" and therefore facilitate operation of the ITS system.

A server such as servers <NUM>, <NUM> or <NUM>, or central ITS subsystem <NUM>, roadside ITS subsystem <NUM>, vehicle ITS system <NUM>, personal ITS subsystem <NUM>, tractor ITS unit <NUM>, network server <NUM>, tractor ITS unit <NUM>, network server <NUM>, tractor ITS unit <NUM>, network servers <NUM>, tractor ITS unit <NUM>, and/or network server <NUM>, may be any network node. For example, one simplified network node that may perform the embodiments described above is provided with regards to <FIG>.

In <FIG>, network node <NUM> includes a processor <NUM> and a communications subsystem <NUM>, where the processor <NUM> and communications subsystem <NUM> cooperate to perform the methods of the embodiments described herein.

The processor <NUM> is configured to execute programmable logic, which may be stored, along with data, on the network node <NUM>, and is shown in the example of <FIG> as memory <NUM>. The memory <NUM> can be any tangible, non-transitory computer readable storage medium, such as DRAM, Flash, optical (e.g., CD, DVD, etc.), magnetic (e.g., tape), flash drive, hard drive, or other memory known in the art. In one embodiment, processor <NUM> may also be implemented entirely in hardware and not require any stored program to execute logic functions.

Alternatively, or in addition to the memory <NUM>, the network node <NUM> may access data or programmable logic from an external storage medium, for example through the communications subsystem <NUM>.

The communications subsystem <NUM> allows the network node <NUM> to communicate with other devices or network elements.

Claim 1:
A method at a first computing device within an Intelligent Transportation System for a platoon or vehicle length reporting wherein the first computing device is associated with a lead vehicle (<NUM>) of the platoon, the method comprising:
receiving, at the first computing device, a reported position from a second computing device associated with an end vehicle (<NUM>) of the platoon;
finding position information for the first computing device;
calculating a difference between the position found for the first computing device and the position reported from the second computing device; and
using the difference for a platoon vehicle length reporting;
characterised in that it further comprises:
receiving a position from a third computing device associated with an intermediate vehicle;
calculating a difference between the position found for the first computing device and the reported position of the third computing device; and
ignoring the difference between the position found for the first computing device and the reported position of the third computing device when the difference is shorter than the difference between the position found for the first computing device and the reported position from the second computing device.