FIELD OF THE INVENTION

The present invention relates to driving assistance systems and relates in particular to a speed variation monitoring system for a plurality of road vehicles and a communication method carried out in such a system.

BACKGROUND OF THE INVENTION

It is known in the prior art, for example from KR20100069960, to detect a particular braking condition in a road vehicle and to wirelessly transmit such a condition directly to following vehicles in order to notify the following vehicles with a possible hazardous situation.

However, the range of such a wireless communication is limited, and the transmission of such a condition is made irrespective of the vehicles geolocation leading to irrelevant warnings over space and time.

The goal of the present invention is to improve such communication systems and methods of sensing and distributing the relevant information, thereby improving the safety of the road traffic.

SUMMARY OF THE DISCLOSURE

According to the disclosure, there is provided a method carried out by a system adapted to collect and distribute traffic information, in a system comprising:

- a plurality of reporting mobile devices, each located in a vehicle, wherein each of the reporting mobile device comprises geolocating means to determine a current location and means to determine a deceleration of said vehicle,

- at least a target mobile device, located in a target vehicle, having an output,

- at least a host server,

wherein each of the plurality of reporting mobile devices is arranged to wirelessly send information to the host server, wherein the host server is arranged to wirelessly send information to the target mobile device,

wherein the method comprises the steps of:

/a/ a deceleration identification step, in which a reporting mobile device determines a deceleration condition in which the deceleration of the vehicle exceeds a predetermined threshold condition,

/b/ an uploading step in which the reporting mobile device transmits to the host server a deceleration message comprising the deceleration condition information associated with the corresponding current location,

/c/ a gathering step, in which the host server gathers various deceleration messages from various reporting mobile devices, received over a certain time,

/d/ a filtering step, in which the host server eliminates deceleration messages resulting from normal traffic condition like crossroads, tolls or speed limit changes, and in which the host server defines, from the geolocations received in the remaining deceleration messages, a filtered list of deceleration areas,

/e/ a downloading step in which the host server transmits to the target mobile device at least a portion of the filtered list of deceleration areas,

/f/ the target mobile device delivers deceleration areas to the output.

Thanks to these dispositions, the user of the vehicle in which a target mobile device is installed is informed of relevant deceleration areas in the vicinity, or ahead in the itinerary, which is beneficial for the traffic overall safety .

The deceleration areas may be a roadwork area, a sudden speed decrease area, a poor road quality area with potholes, a usual traffic jam area, an inadvertent event occurred on the road, a dangerous curve, etc.

In various embodiments of the invention, one may possibly have recourse in addition to one and/or other of the following arrangements:

- the reporting mobile devices may comprise an accelerometer and in the deceleration identification step (/a/), the vehicle deceleration is computed from the information delivered by the accelerometer; whereby the actual knowledge of the speed is not necessary;

- in the deceleration identification step (/a/), the vehicle deceleration may be computed with a time derivation of the geolocation of the vehicle; whereby an accelerometer is not necessarily required;

- the target mobile device comprises an audio or display user interface and the target mobile device outputs deceleration areas to the user interface; whereby it is provided an autonomous target mobile device to notify deceleration areas to the user;

- the target mobile device comprises geolocating means to determine a current location and a cartographic database, and the target mobile device filters the list of deceleration areas to keep only the deceleration areas located on the traveled road segment and in vicinity of the traveled road segment; whereby only relevant deceleration areas are notified to the user;

- the target mobile device comprises geolocating means to determine a current location, a cartographic database, and a planned itinerary, and the target mobile device filters the list of deceleration areas to keep only the deceleration areas located on a corridor around the planned itinerary; whereby only very relevant deceleration areas are notified to the user;

- the predetermined threshold condition comprises a braking condition, and/or a user prompted action; thereby improving the relevance of the notified deceleration areas;

- the host server accumulates the deceleration messages over a predetermined period of time; whereby the reliability of the determination of the deceleration areas is improved;

- the deceleration message comprises a rating parameter representative of the intensity of the deceleration; whereby improving the relevance of the information supplied to the user.

The present invention is also directed to a communication system adapted to collect and distribute traffic information, said system comprising

- a plurality of reporting mobile devices, each located in a vehicle, wherein each of the reporting mobile device comprises geolocating means to determine a current location and a means to determine a deceleration of said vehicle,

- at least a target mobile device, located in a target vehicle, having an output,

- at least a host server,

wherein each of the plurality of reporting mobile devices is arranged to determine a deceleration condition in which the speed of the vehicle decreases more than a predetermined threshold condition, and to wirelessly transmit to the host server a deceleration message comprising the deceleration condition information associated with the corresponding current location,

wherein the host server is arranged to gathers various deceleration messages from various reporting mobile devices, and to eliminate deceleration messages resulting from normal traffic condition like crossroads, tolls or speed limit changes, and in which the host server is arranged to define a filtered list of deceleration areas, and to wirelessly transmit to the target mobile device a filtered list of deceleration areas.

In various embodiments of the invention, one may possibly have recourse in addition to one and/or other of the following arrangements:

- the target mobile device may have an audio or display user interface, and the target mobile device may be arranged to output deceleration areas to the user interface; thereby providing an autonomous device;

- the target mobile device may comprise geolocating means to determine a current location and a cartographic database; thereby enabling to notify to the user only relevant deceleration areas;

- the reporting mobile device may further comprise a brake input to sense a braking condition; thereby the reliability of the deceleration detection is improved;

- the reporting mobile device may further comprise further comprises an accelerometer arranged to sense a deceleration; thereby the reliability of the deceleration detection is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention appear from the following detailed description of one of its embodiment, given by way of non-limiting example, and with reference to the accompanying drawings.

In the drawings:

- Figure 1 is a general view of the system according to the invention,

- Figure 2 illustrates road segments on which vehicles are travelling,

- Figure 3 is a diagram illustrating the method,

- Figure 4 illustrates the deceleration condition determination,

- Figure 5 and 6 show block diagrams of respectively a target mobile device and a reporting mobile device.

MORE DETAILLED DESCRIPTION OF THE INVENTION

In the figures, the same references denote identical or similar elements.

Figure 1 shows a general view of the system according to an embodiment of the invention. The system comprises a plurality of road vehicles 90,91,92 like automobiles, trucks, motorcycles, commercial vehicles. Although three vehicles are shown on the figure, the number of vehicles involved in the proposed system is not limited to three, and as it will be explained later, a high number of vehicles may be involved in the system.

Further, there is provided a plurality of mobile devices 1,2, installed on vehicles (vehicles denoted 90,91 in the shown example) . More precisely, some mobile devices are called reporting mobile devices 1, and other ones, at least one, is called target mobile device 2 whose purpose and functions will be detailed later.

Each of the reporting mobile device 1 comprises geolocating means to determine the current location of the vehicle in which the reporting mobile device is installed.

Said geolocating means may be a device receiving satellites signals (from satellites 7) like a GPS receiver, a Glonass receiver, a Galileo receiver or the like, enabling to determine the current geolocation.

According to one aspect of the invention, the reporting mobile device 1 may comprise an accelerometer 29 able to sense the deceleration and acceleration of the vehicle, in particular the longitudinal deceleration.

Alternatively, a time derivation of the geolocation computed by the mobile device may further provide a speed information representative of the speed of the vehicle. From the vehicle speed information, a deviation monitoring can be performed, as explained below in reference to Figure 4. According to another manner, a time derivation of the speed information leads to a deceleration information, which can be used to determine the condition of step /a/ of the method which is explained below.

It is to be noted that the speed information provided by the original electronic equipment of the vehicle.

The system further comprises a host server 3, adapted to exchange information with the mobile devices 1,2. Using several servers instead of one is of course possible.

More particularly, the reporting mobile device 1 is arranged to wirelessly send information to the host server 3, via messages 18.

The messages 18, also called uplink messages 18, can be supported by any type of known wireless infrastructure like GSM, GPRS, CDMA UMTS, WiFi, 802. llx or any other wireless system in the art. Such wireless systems are known in the art, so they are not detailed in the present specification .

It should be understood that said mobile device 1 may be for example a Personal Navigation Device ('PND'), a smart phone, a data collector unit (also known as 'black box') or a device integrated in the vehicle original equipment .

As shown in Figure 6, the reporting mobile device 1 comprises a wireless communication interface 21, geolocating means 22, a processing unit 23. Further, it may comprise a memory unit 24, and/or the already mentioned accelerometer 29.

Regarding the target mobile device 2, it can also be for example a Personal Navigation Device, a smart phone, or a device integrated in the vehicle original equipment. In the shown example, it is installed in the vehicle with reference numeral 92.

The target mobile device 2 may be a device which is integrated into the vehicle original equipment, or the target mobile device 2 may be a separate device having a simple output adapted to transmit data to an original equipment user interface already provided in the vehicle.

The target mobile device 2 may also be an autonomous device with an audio or display user interface, like in the case of a smart phone or a PND .

The target mobile device 2 is adapted to receive messages 28 from the host server, in other words, the host server 3 is arranged to wirelessly send information to mobile devices in general and particularly to the target mobile device 2.

The messages 28, also called downlink messages 28, sent from the host server 3, can be supported by any type of known wireless infrastructure, the same or a different one with regard to the uplink messages 18.

As shown in Figure 5, the target mobile device 2 comprises a wireless communication interface 21, a processing unit 23 and a memory unit 24. The target mobile device 2 may optionally comprise a geolocating means 22 to determine a current location, analogous or similar to geolocating means already described for the reporting mobile device 1.

The target mobile device 2 may optionally comprise a cartographic database and a display device 27, arranged to display to the user a current map and additional information related to the traffic.

Referring now to Figure 2, reference 4 denotes a road network with a main road 42 and smaller roads 43,44 connected to said main road 42, vehicle normally circulating on the right side of the road.

The method carried out in the system is now described below, referring to Figures 1-4.

At each reporting mobile device 1, there is performed a deceleration identification step (/a/), in which the reporting mobile device 1 determines a deceleration condition. Said deceleration condition is determined whenever the speed of the deceleration of the vehicle exceeds a predetermined threshold condition.

When using the accelerometer 29, the processing unit 23 computes in real time the deceleration given by the accelerometer, and the predetermined threshold condition may be verified if the sum of deceleration over a certain time is exceeded. When using the speed computed from a time derivation from the geolocation, the threshold condition can be verified for example, as illustrated in Figure 4 which shows a vehicle speed profile 61 over time, if the vehicle speed decreases more than 'DeltaV over a period of ^y DT' seconds (corresponding to line 60); in the shown case, the speed decrease rate 62 exceeds the threshold rate 60.

Another possible solution is to analyze in real time the deceleration of the vehicle through time derivation of speed, and determine the deceleration condition whenever the deceleration is greater than a predetermined threshold.

Optionally, the threshold condition can also comprise a brake information 17 (cf . Figure 6) available from the vehicle braking system.

Optionally, the threshold condition can also comprise a user prompted action like turning on the hazard lights, or actuating any push button.

Of course, the threshold condition may comprise a logical combination with 'AND' and ^y OR' relative to the different possibilities explained above, for instance according to a parameterization decided by a system administrator and transferred wirelessly to the reporting mobile device 1.

Additionally, the reporting mobile device 1 may evaluate a rating parameter representative of the intensity of the deceleration. This parameter could be for example a number proportional to the deceleration ratio.

Whenever a deceleration condition is detected, the current geolocation of the vehicle is memorized and is associated with the deceleration condition.

At each reporting mobile device 1, there is performed an uploading step (/b/) in which the reporting mobile device 1 transmits to the host server 3 a deceleration message 18 comprising the deceleration condition information associated with the corresponding current location of the concerned vehicle, and possibly the rating parameter .

It should be noted that the deceleration messages 18 may be transmitted in an asynchronous mode without being stored on the reporting mobile device, or the deceleration messages may be stored in a local memory and transmitted on periodic time base, to decrease wireless network load or to cope with temporary unavailability of the wireless infrastructure .

Turning now to the host server 3, there is performed a gathering step {Id), in which the host server 3 gathers various or all deceleration messages 18 from various reporting mobile devices 1, received over a certain time, for example the latest three-day period. Regarding the filtering over a particular geographical area, the host server 3 may manage a partition of a whole country into different geographical areas.

In the example shown in Figure 2, there are five vehicles 90-91,93-95 having each a reporting mobile device 1 onboard. More precisely, vehicle 95 is decelerating when arriving at a crossroad 40, and therefore the deceleration condition is verified and a deceleration 18 is sent toward the server 3 from vehicle 95. Vehicle 94 is also decelerating, for any reason, for example its driver has identified a relevant reason to decelerate or brake; therefore a deceleration message 18 is sent toward the server 3 from vehicle 94. Some time later, the vehicle 91 will reach a sharp curve 41, and the driver will brake, therefore triggering another deceleration message 18 to be sent toward the server 3 from vehicle 91 having a geolocation in the deceleration area 53. Some time later, vehicle 93 will also brake arriving at area 50, thereby triggering the sending of another deceleration message 18.

Also, some time before the situation shown in Figure 2, vehicle 90 has also passed in the area 50 and had possibly braked, thereby triggering a deceleration message 18 from vehicle 90.

Any deceleration message 18 comprises the current location of the concerned vehicle, so the message of vehicle 90 takes place before the message of vehicle 94, but they both contain similar geolocations , i.e. the beginning of area 50. Therefore, the host server 3, by aggregating the various messages 18 received from reporting mobile devices 1, is able to define a deceleration area, i.e. a rather small road area from where several deceleration messages 18 emanate.

The deceleration area 50 encompasses all the locations from where neighboring deceleration messages 18 were received .

In order to optimize the size of the deceleration area 50, additional uplink message are considered when vehicle 94 is accelerating again. If vehicle accelerated more than a predetermined value over a certain time, then an acceleration message is transmitted to the host server. This message can help the server to define the forward end 50a of the deceleration area 50.

At the host server 3, there is also performed a filtering step (/d/), in which the host server 3 eliminates deceleration messages resulting from normal traffic condition like crossroads, tolls or speed limit changes, and in which the host server 3 defines a filtered list of deceleration areas.

More precisely, in the area 52 comprising a stop signal instruction, the deceleration of all vehicles are expected, and therefore the deceleration message 18a sent from this area do not give valuable information, whereas in area 50, which is straight, the deceleration of vehicles are not particularly expected, therefore deceleration messages 18 sent from this area 50 give valuable information, and the following vehicles (like vehicle 92) can warned of such an unexpected situation.

Regarding now areas 53,54, the elimination of the deceleration message coming from these areas may depend upon parameterization. Upon parameterization, deceleration messages preceding a tight curve may or may not be eliminated in the filtering operation.

Further, at the host server 3, there is performed a downloading step (/e/) in which the host server 3 broadcast through the wireless infrastructure a filtered list of deceleration areas. More particularly, the host server 3 transmits to the target mobile device 2 located in the vehicle 92 a filtered list of deceleration areas 50,53,54.

As explained above, the host server 3 may manage a partition of a country into different geographical areas, and in such a case, the content of the broadcasted information depends upon respective antennas belonging to the wireless infrastructure, thereby having relevant notifications of deceleration areas omitting to notify deceleration areas which are far away from the vehicle in which target mobile device 2 is installed.

Therefore, in the shown example, the user of vehicle 92, via the operation of the target mobile device 2, can be notified about various deceleration areas, and in particular relevant deceleration areas 50,53.

Further, in step referenced /f/, the target mobile device delivers deceleration areas to the output, this output being either adapted to transmit data to an original equipment user interface already provided in the vehicle as already explained, or this output being the audio or display of the target mobile device 2 itself.

The target mobile device 2 may eliminate area 54 which is in opposite direction with regard to the direction in which the vehicle 92 travels.

According to an optional feature of the embodiment, the target mobile device 2 may comprise a cartographic database 26 and a display device and in this case the target mobile device filters the list of deceleration areas to keep only the deceleration areas located ahead on the traveled road segment. This filtered list preferably also includes the deceleration areas located in vicinity of the traveled road segment, for example in roads segments located within a predetermined distance from the traveled segment.

It should be noted that the way by which the notice of the deceleration areas is given will preferably exhibit a hierarchy based on the distance of each deceleration area from the current location of vehicle 92, for example the smaller the distance is, the higher is the notice in the list. If a map display is used the priority is given to the notices of deceleration areas located ahead in the traveled segment .

According to a further optional feature of the embodiment, the target mobile device 2 comprises a planned itinerary 8, and the target mobile device filters the list of deceleration areas to keep only the deceleration areas located on a corridor around the planned itinerary, said corridor being for example defined by road segments located within a predetermined distance from the itinerary.

According to another aspect of the invention, there are provided additional fixed sensing devices, like road video surveillance for instance, which may result in additional deceleration areas, for example in tunnels or in areas where the wireless infrastructure and/or GPS is not available or out of order.

According to another aspect of the invention, the deceleration message may comprise a rating parameter representative of the intensity of the deceleration. For instance, an emergency braking would be allocated with a high rating. This rating could also be provided consequently to corresponding deceleration areas, for instance by having different displayed colors representative of the possible dangerousness of the various deceleration areas.

The deceleration areas may be ranked according to different parameters like the number of messages, the intensity of deceleration, the time lapsed since the last messages, etc...

It shall be understood that the reliability of the information gathered from various vehicles having a reporting mobile device is improved if the number of such vehicles is high. A high number of reporting mobile devices is beneficial to the host server filtering step (/d/), and statistical computation can take place.

Also, it will be apparent for the person skilled in the art that certain type of mobile devices can support both the functions of the reporting mobile device and the target mobile device, and in such a case there may be a single type of mobile device 1,2.