Field of the invention

The present invention relates to adaptive cruise control systems and methods for a motor vehicle.

Specifically, the invention relates to a system of the type comprising:

- an electronic horizon system, including a position sensor for determining the current position of the motor vehicle, a memory containing map-like data on a road network, and an electronic processing unit, configured to generate predictive information on the characteristics of the road that the motor vehicle must travel, based on the position detected by said position sensor and on the road network data made available by said memory,

- a communication device for communicating with a remote server, configured to provide said electronic processing unit with further data on the characteristics and/or conditions of the road that the motor vehicle must travel, and

- additional sensors carried by the motor vehicle and configured to perceive the environment surrounding the motor vehicle and to send corresponding data to said electronic processing unit.

Prior art

Systems of the type indicated above have already been proposed. Specifically, electronic horizon systems of the aforementioned type, configured to provide the driver with information on the road in front of the motor vehicle even beyond the horizon actually visible to the driver, have already been proposed and developed.

A system of the type described above is known for example from document EP 1 775 552 A2.

The present invention starts from the idea of exploiting an electronic horizon system of the type indicated above to provide an adaptive cruise control, that does not require the intervention of the driver and can be implemented both on conventional vehicles and on self-driving vehicles.

Document US2021/009128A1 discloses an adaptive cruise control system for a motor vehicle corresponding to the pre-characterizing part of claim 1. Another document relating to the technological background is represented by the article: “Design of look-ahead control for road vehicles using traffic information”, 22nd Mediterranean Conference on Control and Automation, IEEE, 16 June 2014 (2014-06-16), pages 201 -206, XP032687217.

Object of the invention

It is therefore an object of the present invention to provide an adaptive cruise control system and method for a motor vehicle, that have high efficiency and precision properties, enable the driver to obtain predictive information on the road that the motor vehicle is intended to meet and nevertheless can be implemented with simple and low-cost means.

A further object of the invention is to provide a system and a method of the type specified above that ensure control of the motor vehicle based on an “eco-type” driving criterion, i.e. such as to keep energy consumption to a minimum, both in the case of conventional motor vehicles with internal combustion engines, and in the case of hybrid vehicles and electric vehicles.

Summary of the invention

In view of achieving one or more of the aforementioned objects, the invention relates to an adaptive cruise control system for a motor vehicle having the features of claim 1 .

As indicated, on the basis of the order of importance associated with each critical point and each critical condition, on the basis of the reference speed associated with each of said critical points and said critical conditions, i.e. on the basis of the predetermined speed value with which the motor vehicle must meet these critical points or critical conditions, and on the basis of the distance that separates the motor vehicle from each of the critical points or critical conditions, the electronic processing unit associates a weight to each critical point and each critical condition and is therefore able to select the critical point or critical condition with the highest weight. The electronic processing unit then controls the motor vehicle so as to bring the motor vehicle speed from the current value to the reference value associated with the selected critical point or the selected critical condition. In making this, the electronic processing unit takes into account an “eco” driving criterion aimed at reducing energy consumption as much as possible. For example, if the critical point selected is a roundabout and if the motor vehicle is at a predetermined distance from this roundabout and has a predetermined current speed, the electronic processing unit will cause the motor vehicle speed to decrease from the current value to the reference speed according to a speed profile that ensures the minimum energy consumption.

In a preferred embodiment, said electronic processing unit is configured to process different speed profiles according to different predetermined logics and to select, among said profiles, the speed profile that requires the lowest energy consumption and to control the motor vehicle according to said selected speed profile.

Preferably, the predetermined criterion of importance with which the identified critical points are classified is chosen in such a way as to give primary importance to critical points that have greater relevance for the safety of the motor vehicle and its occupants, for example as they involve a complete stop of the motor vehicle, such as road stops, traffic lights, interruptions and queues due to road accidents or road works.

The invention also relates to the control method implemented through the system described above.

Detailed description of the invention

Further features and advantages of the invention will appear from the following description with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

- figure 1 is a schematic view of a motor vehicle equipped with a system according to the invention,

- figure 2 is a block diagram illustrating the operating principle of the system according to the invention, and

-figures 3, 4 illustrate examples of road routes including critical points (a dangerous curve and a climb with subsequent descent) and the speed profiles that are selected by the system according to the invention.

Figure 1 schematically illustrates an embodiment of the system according to the invention. In this example, a motor vehicle 1 includes an electronic processing unit E which receives data from a position sensor 2 able to determine the current position of the motor vehicle (for example a GPS sensor), from a memory M containing map-like data on a road network, from a communication device 3 configured to communicate with a remote server, and to supply the electronic processing unit E with further data on the characteristics and/or conditions of the road that the motor vehicle must travel, and from a plurality of additional sensors S1 , S2, ..., Si (for example radar sensors, LiDAR, video cameras) configured to perceive the environment surrounding the motor vehicle and to send corresponding data to the electronic processing unit E. The memory M, containing the map-like data on a road network, can be located on board the motor vehicle or can be located in a remote server, with which the electronic processing unit E communicates through the communication device 3.

On the basis of the data sent by the position sensor 2, by the memory M, by the sensors S1 , S2, ..., Si, and by the communication device 3, the electronic processing unit E is configured to generate an “electronic horizon”, i.e. predictive information on the characteristics of the road that the motor vehicle must travel. The information is displayed on a manmachine interface HMI 4, arranged for example on the dashboard of the motor vehicle and including a display and an audio communication system.

In the system according to the invention, the electronic processing unit E is configured to carry out the following operations continuously and cyclically, with a predetermined periodicity:

- identifying, in a stretch of road in front of the motor vehicle, a plurality of critical points (that in figure 2 are represented by the corresponding road signs) such as, for example, a dangerous curve 5, a roundabout 6, an area with roadworks 7, a climb 8 with a slope greater than a predetermined threshold value, a traffic light 9, a stretch of road 10 signaled as a generic danger area, a stretch of road 11 with an upper speed limit.

The electronic processing unit E is also configured to associate to each of the critical points 5-11 a corresponding reference value Vref of the motor vehicle speed, corresponding to the speed that the motor vehicle must have when it is at the selected point in order to guarantee a correct and safe operating condition of the motor vehicle. Each critical point identified is also associated with the “d” value of the distance that separates the motor vehicle from each specific critical point or from each specific critical condition.

Still according to the invention, once a speed reference value and a distance have been associated with each identified critical point, the electronic processing unit executes a first loop of operations in block 12 of Figure 2 in order to associate a “weight” to each of the critical points identified.

To this end, the identified critical points are classified on the basis of a predetermined criterion of importance. In a preferred example, greater importance is given to the critical points that have greater relevance for the safety of the motor vehicle and its occupants, as they involve, for example, a complete stop of the motor vehicle, such as for example road stops, traffic lights and interruptions and queues due to road accidents or road works. Whatever the criterion of importance adopted, this criterion is preliminarily programmed in the electronic processing unit E.

The “weight” to be associated with each critical point is therefore determined by the electronic processing unit both on the basis of the aforementioned criterion of importance and on the basis of the value of the corresponding reference speed and the corresponding distance. The operations are performed in block 12, in such a way as to send the result 13 of the weighing operation to logic block 14, that corresponds to the execution of a second loop of operations, the result of which is the selection of the first critical point to be considered, with the indication of the distance that separates it from the current position of the motor vehicle and the speed reference value associated with the selected critical point.

Following the selection made in block 14, in block 15 the electronic processing unit processes a profile of the speed variation with which the motor vehicle must be controlled in order to pass from its current speed to the predetermined reference speed with which the motor vehicle must meet the selected point.

The operations of block 15 are programmed according to a criterion that favors the containment of energy consumption. For example, the electronic processing unit can be programmed to process different speed profiles, to choose, among these profiles, the one that achieves the lowest energy consumption. This means that if, for example, the motor vehicle is currently at a speed V1 and must arrive within a distance d at a speed V2 < V1 , the motor vehicle speed begins to be decreased immediately, or in any case when the distance separating the motor vehicle from the selected point gets below a predetermined threshold value, after which the speed continues to be decreased in a gradual and substantially linear manner, so as to avoid useless waste of energy. Block 15 is therefore dedicated to defining the optimum profile of the speed variation of the motor vehicle.

Figure 3 shows an example of use of the system according to the invention. At time t = 0, the motor vehicle travels at a speed V equal to 130 km/h. On the basis of the method described above, the electronic processing unit E selects a dangerous curve 16 as the critical point of the highest weight which must be traveled at a speed Vref equal to 116 km/h. The system maintains the motor vehicle speed at a value of 130 km/h up to the time t = 32 seconds. Starting from this time, the speed is decreased linearly in a time of about 2 seconds up to the required value of 116 km/h. This value is maintained until time t = 48 seconds, that corresponds to the completion of curve 16, after which the speed is brought back to the cruising value of 130 km/h. In the diagram at the bottom of Figure 3, the line V indicates the actual change in vehicle speed. Line R indicates the variation along the curve of the safety speed value selected by the system through the weight logic explained previously. In this case the curve has a curvature that varies at each point, so the safety speed is calculated for each point of the curve. Among all these speed values, the system considers the minimum value and sets it as the speed to cover the entire curve.

Figure 4 illustrates a similar example, in the case in which the critical point selected is a climb road stretch followed by a descent road stretch (the figure represents the climb and descent in a schematic way, with a curve having the profile that is actually the vertical profile of the road). From time t = 0 to time t = 18 seconds, the speed value of the motor vehicle is 130 km/h. From time t = 18.5 seconds to time t = 19.5 seconds, the speed V of the motor vehicle is increased progressively with steps that simulate a linear variation, up to the speed of 135 Km/h, after which the speed is decreased to a value of 125 km/h at time t = 21 seconds. Also in this case the graph in the lower part of the figure shows the variation V of the motor vehicle speed. Line R in figure 4 represents the “Required Speed”, i.e. the speed selected by the system using the weight logic previously explained. At the time t = 18.5 seconds, the speed requested by the system is 135 km/h and, as illustrated, the control brings the motor vehicle speed to the requested speed with an “eco” profile with consecutive speed variations of 1 km/h. In the same way, when the speed requested by the system through the weight logic lowers to 125 km/h (t = 19.5 seconds), the motor vehicle speed profile decreases with consecutive speed variations of 1 km/h, until it reaches the 125 km/h required.

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