TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates in general to driver-assistance systems for motor vehicles. In particular, the invention regards a driverassistance system that can be used both in a conventional motor vehicle and in an autonomous-driving motor vehicle, of the type comprising means for determining the distance of the vehicle from an object in front of the vehicle, for example from another vehicle that precedes it or from an obstacle.

Prior art

Stereovision is a known technique used for determining the distance of a vehicle from an object in front of it with the aid of two or more video cameras that detect the scene in front of the vehicle and that are provided in the front part of the vehicle or inside the passenger compartment adjacent to the windscreen of the vehicle. This solution is already used in vehicles equipped with ADAS (Advanced Driver- Assistance Systems). Such systems are, for example, used for activating a warning signal for the driver when the distance from a vehicle that precedes his own vehicle drops below a threshold value, taking into account the current speed of the vehicle and the consequent braking space, and/or for activating automatic braking of the vehicle.

Figure 1 of the annexed drawings is a schematic top plan view of a vehicle 1 of the known type mentioned above, provided with two video cameras 2 that detect the scene in front of the vehicle, with a view to enabling an electronic control unit on board the vehicle to receive the signals at output from the video cameras 2 and calculate the distance of the vehicle from an object X in front of it (which may, for example, be another vehicle or else an obstacle of any type). In comparison with more sophisticated systems, as for example the LIDAR systems, a stereovision system only involves the use of video cameras operating in the range of visible light and consequently represents a simple and relatively inexpensive solution. The advantage of such systems moreover lies in the fact that they cover the entire field of vision in front of the vehicle. The distance is calculated as a function of the focal length of the lens of each video camera, as a function of the length of the baseline b corresponding to the distance between the two video cameras, and as a function of the “disparity” between the images of the two video cameras, i.e., of the difference in position of one and the same point of the scene in front of the vehicle in the two images formed by the video cameras 2.

However, there remains the fact that, in solutions of this type, the error in the measurement of the distance of the vehicle from the object in front of the vehicle increases with the square of the distance and is inversely proportional to the length of the baseline b. This poses a major limit to the precision of the system in so far as in any application of practical interest the distance between the two video cameras of the vehicle cannot be greater than the width of the vehicle.

Object of the invention

The object of the present invention is to provide a vehicle equipped with a system for detecting the distance of an object in front of the vehicle on the basis of a communication of a V2X type with other vehicles and on the basis of a detection of position.

A further object is to implement a detection system that will be simple and of low cost, but that at the same time will increase considerably the precision of detection as compared to known systems.

Summary of the invention

According to a first aspect, the subject of the invention is a vehicle comprising:

- a video camera for forming an image of the scene in front of the vehicle;

- an electronic control unit configured for receiving a signal from the video camera and processing first image data on the basis of said signal; - a location module configured for sending to said electronic control unit first position data of the vehicle; and

- a communication module configured for receiving from a communication module of another adjacent vehicle:

- second image data obtained on the basis of the signal of a video camera provided on the adjacent vehicle for forming an image of the scene in front of the adjacent vehicle, and

- second position data of the adjacent vehicle;

- said electronic control unit moreover being configured for:

- determining the distance between the vehicle and the adjacent vehicle on the basis of said first position data and said second position data; and

- processing stereoscopic-image data on the basis of the first image data, of the second image data, and of said distance determined between the vehicle and the adjacent vehicle, and for calculating, as a function of said stereoscopic-image data, the distance of the vehicle from an object in front of the vehicle.

As will emerge in greater detail from the ensuing description, the fundamental idea underlying the present invention is to increase considerably the precision of detection of the distance of the vehicle from an object in front of it thanks to a drastic increase in the length of the baseline mentioned above, i.e., of the distance between the two video cameras that are used for detection. This is obtained in practice using two video cameras provided on two different vehicles. The vehicle according to the invention is for this reason provided with a communication module configured for receiving from a communication module of an adjacent vehicle the image data obtained on the basis of the signal of a video camera provided on the adjacent vehicle.

At the same time, the electronic control unit of the vehicle according to the invention is configured for calculating the distance between the video camera on board the vehicle and the video camera on board the adjacent vehicle using a location module of any known type on board the vehicle and configuring the aforesaid communication module of the vehicle for receiving from the communication module of the adjacent vehicle also position data of the adjacent vehicle. On the basis of the data detected by the systems on board the vehicle and on the basis of the data transmitted to the communication module of the vehicle by the communication module of the adjacent vehicle, the electronic control unit of the vehicle according to the invention is consequently able to determine the distance between the two vehicles and to process stereoscopic-image data on the basis of the image data generated by the two video cameras, and calculate, as a function of said stereoscopic-image data, the distance of the vehicle from an object in front of it.

Communication between the communication modules of the two vehicles may be obtained according to any known technique and may be periodic (for example, with broadcast messages filtered at a frequency of from 1 Hz to 10 Hz, like a radio beacon) according to techniques in themselves known in the field of safety systems for autonomous-driving vehicles. The periodicity of the communication may be selected in relation to the speed of the vehicles to enable the stereovision system to know how to calculate the distances. Alternatively, it is possible to envisage generation of a communication only in the case of a specific event, i.e., when the communication is necessary and when there arise the proper conditions, for example when on-board systems of the vehicle detect the presence of an adjacent vehicle.

In the preferred embodiment, the communication module of the vehicle according to the invention is moreover configured for receiving, from the communication module of the adjacent vehicle, data of direction and speed of movement of the adjacent vehicle, and said electronic control unit is configured for processing the stereoscopic-image data and for calculating the distance of the vehicle from an object in front of the vehicle also on the basis of said data of direction and speed of movement of the adjacent vehicle.

According to a further important characteristic, the communication module of the vehicle according to the invention is moreover configured for receiving, from the communication module of the adjacent vehicle, data indicating the optical characteristics of the video camera of the adjacent vehicle, and said electronic control unit is configured for processing said stereoscopic-image data and for calculating the distance of the vehicle from an object in front of the vehicle also on the basis of said data indicating the optical characteristics of the video camera of the adjacent vehicle.

Preferably, the vehicle according to the invention has its own communication module configured for transmitting, in turn, to the communication module of an adjacent vehicle the aforesaid first image data processed on the basis of the signal of the video camera on board the vehicle, the aforesaid first position data of the vehicle obtained via the location module on board the vehicle, preferably also the data of direction and speed of movement of the vehicle, and preferably also the data indicating the optical characteristics of the video camera on board the vehicle. In this way, an adjacent vehicle, itself built in conformance with the teachings of the present invention, will be able to detect, in turn, the distance of an obstacle in front of the adjacent vehicle.

According to another aspect, the subject of the invention is a fleet of vehicles, wherein each vehicle comprises the characteristics referred to above, as well as a driver-assistance method for a plurality of vehicles, which comprises providing a plurality of vehicles, wherein, when two or more vehicles are adjacent to one another, the communication modules of any two vehicles exchange with one another the aforesaid image data, the aforesaid position data, and preferably also the data of direction and speed of movement, and likewise preferably the data regarding the optical characteristics of the video cameras in such a way as to enable detection, on board each vehicle, of the distance from an object in front of it.

In the method according to the invention it is also possible to envisage that the communication modules of the vehicles will be configured for exchanging identification codes that enable activation of the operations necessary for detecting, on board each vehicle, when a vehicle according to the invention detects the presence of another vehicle according to the invention adjacent thereto.

Detailed description of the invention

Further characteristics and advantages of the invention will emerge from the ensuing description, with reference to the annexed drawings, which are provided purely by way of non-limiting example and in which: - Figure 1 is a schematic top plan view of a vehicle equipped with a stereovision system according to the prior art;

- Figure 2 is a top plan view that shows the principle underlying the present invention, with reference to an example with two vehicles according to the invention that travel alongside one another in two parallel directions;

- Figure 3 is a schematic view that shows the two images of the scene in front formed by the two video cameras associated to the two vehicles of Figure 2;

- Figure 4 is a schematic top plan view that shows the operating principle of the present invention with reference to an example in which two vehicles according to the invention travel in two parallel directions, but with one vehicle slightly ahead of the other vehicle; and

- Figure 5 is a schematic top plan view of two vehicles built in conformance with the present invention, schematically illustrated in which are the components of the system provided on board each vehicle.

In Figures 2-5 the parts corresponding to those of Figure 1 are designated by the same reference numbers.

With reference to Figure 2, a vehicle 1 built in conformance with the present invention is equipped with a single front video camera 2, for example provided on the front part of the vehicle or in the passenger compartment of the vehicle in a position adjacent to the windscreen and configured for forming an image of the scene in front of the vehicle. With reference also to Figure 5, the vehicle 1 comprises an electronic control unit E configured for receiving a signal from the video camera 2 and processing first image data on the basis of said signal. Again with reference to Figure 5, the vehicle 1 is moreover equipped with a location module L of any known type, configured for sending to the electronic control unit E first position data of the vehicle.

Once again with reference to Figure 5, the vehicle 1 further comprises a communication module M configured for communicating with a communication module M of a vehicle 10 that is adjacent to the vehicle 1 and that likewise is built in conformance with the present invention.

In the situation illustrated in Figures 2 and 5, the two vehicles 1 , 10 are moving in two mutually parallel directions and are substantially alongside one another.

Also the vehicle 10 is equipped according to the teachings of the present invention. Consequently, also the vehicle 10 has a front video camera, which in this case is designated by the reference number 20, set in the front part of the vehicle or in the passenger compartment of the vehicle in a position adjacent to the windscreen. Also the vehicle 10 has an electronic control unit E configured for receiving a signal from the video camera 20 and processing image data on the basis of said signal. Also the vehicle 10 is provided with a location module L configured for sending to the electronic control unit E position data of the vehicle. Also in this case, the location unit may be of any known type, but for example is constituted by a GPS satellite-location module. Finally, also the vehicle 10 is equipped with a communication module M.

Each communication module M is configured for enabling a communication of a V2X type exploiting any known technique. For instance, the communication between the two modules M may be a periodic communication based upon broadcast messages that are filtered by the receiver module at a given frequency, for example between 1 Hz and 10 Hz, like a radio beacon. Systems of this type are known and used in safety systems for autonomous-driving vehicles. The periodicity of the communication may be selected in relation to the speed of the vehicles to enable the stereovision system to know how to calculate the distances. Alternatively, the communication between the communication modules M may be activated only when a specific event occurs and when there arise the necessary conditions, for example when sensor systems on board a vehicle detect the presence of an adjacent vehicle.

Of course, the communication systems may envisage transmission of reference codes that confirm the presence of an adjacent vehicle equipped with the system according to the invention and that consequently enable activation of the method for detecting the distance of an object in front of each vehicle.

In the condition illustrated in Figures 2 and 5, the communication module M of the vehicle 1 is consequently able to receive from the communication module M of the vehicle 10 both the image data generated on the basis of the signal of the video camera 20 and the position data of the vehicle 10 detected by the location module L of the vehicle 10. The electronic unit E of the vehicle 1 is configured for determining the distance b between the vehicle 1 and the vehicle 10 (see Figure 2) on the basis of the position data detected by the location modules L of the two vehicles and is moreover able to process stereoscopic-image data on the basis of the image data of the video camera 2, of the image data of the video camera 20, and of the distance b between the two vehicles, and for calculating, as a function of the stereoscopic-image data, the distance of the vehicle 1 from an object X in front of it. Of course, the vehicle 10 may operate in an altogether similar way.

In principle, the stereoscopic-image data may be of any type. In a preferred example, these data in particular include the value of disparity, i.e. , the distance between the positions of one and the same point of the scene in the two images generated by the two video cameras 2, 20.

Figure 3 is a schematic illustration, provided by way of example, of the image IS generated by the video camera 2 of the vehicle 1 and the image ID generated by the video camera 20 of the vehicle 10. In the two images, the obstacle X, represented for example by a lorry that is travelling in front of the two vehicles 1 , 10, is positioned differently, for example at distances X1 , X2, respectively along a reference axis. In this case, the stereoscopic-image data include the difference X2 - X1 .

According to a further preferred characteristic, the communication module M of the vehicle according to the invention is moreover configured for receiving, from the communication module of the adjacent vehicle, also the data of direction and speed of movement of the adjacent vehicle. These data are available in the electronic control unit on board the adjacent vehicle. The data regarding the direction and speed of movement of the adjacent vehicle 10 are used by the electronic control unit E of the vehicle 1 , together with the data on the direction and speed of movement of the vehicle 1 (which likewise are available in the on-board electronic control unit) for carrying out calculation of the distance of the vehicle 1 from the object X in front of the vehicle.

According to a further preferred characteristic, the communication module of the vehicle 1 is moreover configured for receiving, from the communication module of the vehicle 10, data indicating the optical characteristics of the video camera of the vehicle 10, and the electronic control unit E of the vehicle 1 is configured for processing the aforesaid stereoscopic-image data and for calculating the distance of the vehicle 1 from an object in front of the vehicle 1 also on the basis of the aforesaid data indicating the optical characteristics of the video camera 20 of the adjacent vehicle 10. The vehicle 10 is itself configured also in the way referred to above, according to the teachings of the present invention.

Consequently, the communication module of each vehicle according to the present invention may be configured both for receiving data from the communication module of an adjacent vehicle and for transmitting data to the communication module of an adjacent vehicle.

Figure 4 illustrates a situation similar to the one of Figure 2, with the difference that, in this case, the two vehicles 2, 20 are one further ahead of the other in the direction of travel.

As emerges clearly from the foregoing description, the invention makes use of a stereovision system that is extremely simple and of low cost and, notwithstanding this, enables more precise detection of the distance of an object in front of a vehicle, thanks to a greater distancing of the two video cameras used for stereovision.

It is possible to envisage equipping a fleet of vehicles each configured according to the teachings of the present invention. Communication between the communication modules of different vehicles may be obtained so as to include exchange, for example, of recognition codes that enable activation of the operations of detection of the distance of each vehicle from an object in front of the vehicle.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what has been described and illustrated herein purely by way of example, without thereby departing from the scope of the present invention, as defined in the annexed claims.