A METHOD FOR PROVIDING A POSITIVE DECISION SIGNAL FOR A VEHICLE

Abstract

A method for providing a positive decision signal for a vehicle which is about to perform a traffic scenario action. The method includes receiving information about at least one surrounding road user, which information is indicative of distance to the surrounding road user with respect to the vehicle and at least one of speed and acceleration of the surrounding road user; calculating a value based on the received information; providing the positive decision signal to perform the traffic scenario action when the calculated value is fulfilling a predetermined condition. The value is calculated based on an assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration.

Claims

1. A method for providing a positive decision signal for a vehicle which is about to perform a traffic scenario action, such as entering a crossing, entering a highway and/or changing lanes, the method comprising: receiving information about at least one surrounding road user, which information is indicative of distance to the surrounding road user with respect to the vehicle and at least one of speed and acceleration of the surrounding road user; calculating a value based on the received information; providing the positive decision signal to perform the traffic scenario action when the calculated value is fulfilling a predetermined condition, wherein the value is calculated based on an assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration, characterized in that, the surrounding road user is a predefined virtual surrounding road user and the predetermined condition is defined by a threshold value which is indicative of an acceleration limit for the surrounding road user.

2. The method according to claim 1, wherein the value is further calculated based on the assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration after a reaction time.

3. The method according to claim 1, wherein the value is further calculated based on the assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration to an acceleration profile having a constant acceleration.

4. The method according to claim 1, wherein the value is further calculated based on the assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration to an acceleration profile having a variable acceleration.

5. The method according to claim 1, further comprising providing a negative decision signal not to perform the traffic scenario action when the calculated value is not fulfilling the predetermined condition.

6. The method according to claim 1, wherein the threshold value is variable depending on at least one factor, such as any one of speed of the surrounding road user, type of surrounding road user, ambient weather conditions with respect to the vehicle and a state of the surrounding road user, such as a state where a turning indicator is active.

7. The method according to claim 1, wherein the information about the at least one surrounding road user is received by any one of a perception sensor of the vehicle, a V2X communication interface and a remote perception sensor which is in communicative contact with the vehicle.

8. The method according to claim 1, wherein the method is used as a safety control method for an autonomous vehicle, wherein the autonomous vehicle is primarily performing traffic scenario actions by use of a primary autonomous vehicle control method, and wherein a traffic scenario action permitted to be performed by the primary autonomous vehicle control method is allowed to be performed if also the positive decision signal is provided.

9. The method according to claim 1, wherein the calculated value is further based on auxiliary information relating to the traffic scenario action, such as any one of shape and/or dimension(s) of a crossing, a road lane and a neighboring road lane.

10. A method for automatically performing a traffic scenario action of a vehicle, comprising: providing a positive decision signal to perform the traffic scenario action, which positive decision signal has been provided according to the method of claim 1; and automatically performing the traffic scenario action.

11. A method for automatically avoiding performing a traffic scenario action of a vehicle, comprising: providing a negative decision signal not to perform the traffic scenario action, which negative decision signal has been provided according to the method of claim 5; and automatically avoiding performing the traffic scenario action.

12. A control unit for a vehicle which is configured to perform the steps of claim 1.

13. A vehicle comprising the control unit according to claim 12.

14. The vehicle according to claim 13, wherein the vehicle is a fully autonomous or semiautonomous vehicle.

15. The vehicle according to claim 13, wherein the vehicle is a road vehicle, such as a public road vehicle, for example a truck, a bus and a construction equipment vehicle adapted to be driven on a road.

16. The vehicle according to claim 13, wherein the vehicle is a heavy-duty vehicle which has a minimum weight of at least 5000 kg, such as 30.000 kg.

17. A computer program comprising program code means for performing the steps of claim 1, when said program is run on a computer.

18. A computer readable medium carrying a computer program comprising program code means for performing the steps of claim 1, when said program product is run on a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. In the drawings:

[0042] FIG. 1 shows a side view of a heavy-duty truck according to an example embodiment of the present invention;

[0043] FIG. 2 shows a schematic view of a traffic scenario according to an example embodiment of the present invention;

[0044] FIG. 3 shows another schematic view of a traffic scenario according to an example embodiment of the present invention;

[0045] FIG. 4 shows a graph-diagram for illustrating an embodiment of the present invention;

[0046] FIG. 5 shows another graph-based diagram for illustrating an embodiment of the present invention; and

[0047] FIGS. 6a-c show flowcharts of methods according to example embodiments of the present invention

[0048] The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0049] FIG. 1 shows a heavy-duty truck 1, which here is a vehicle combination including the truck 1 and a connected trailer. Even though the following embodiments of the invention will be described with respect to this type of vehicle, it shall be understood that the invention may also be used for other vehicles, such as a bus, a working machine, such as a wheel loader or any other construction equipment vehicle. The invention may also be used for lighter vehicles, such as passenger cars. The heavy-duty truck 1 is in the shown embodiment an autonomous vehicle. The vehicle 1 comprises a control unit 10, which preferably is an electronic control unit, for performing any one of the embodiments of the methods as disclosed herein.

[0050] Now, with respect to FIG. 2, FIG. 4 and FIG. 6a, an example embodiment of the present invention will be described. FIG. 2 shows a schematic view from above of a traffic scenario where a vehicle 1, which may be the truck as shown in FIG. 1, is about to enter a crossing and enter a main road section from a side road section. This is indicated by the arrow bending towards the left in FIG. 2, indicative of that the vehicle 1 is about to make a left-turn and drive in on the main road section. A surrounding road user 2 which is driving on the main road section is also approaching the crossing at a speed v, indicated by the arrow proximate the surrounding road user 2 which is pointing in the direction towards the crossing, so that the vehicle 1 and the surrounding road user 2 risk colliding if the vehicle 1 makes the left-turn. The left-turn is thus in this embodiment a traffic scenario action which the vehicle 1 is about to perform.

[0051] By use of e.g. a perception sensor provided on the vehicle 1 (not shown), the distance d to the surrounding road user 2 with respect to the vehicle 1 may be determined. Further, the perception sensor may also determine the speed v and/or the acceleration of the surrounding road user 2. As mentioned hereinabove, the speed and/or the distance may be determined also by other means, or by a combination of different means, such as by the perception sensor and by V2X information. For example, the V2X information may be V2V (vehicle-to-vehicle) information, wherein the vehicle 1 and the surrounding road user 2 are able to communicate wirelessly and share information between each other.

[0052] According to an example embodiment, also auxiliary information relating to the traffic scenario action may be obtained, such as a dimension of the crossing d.sub.c as shown in FIG. 2. The dimension of the crossing d.sub.c is here indicative of a width of the crossing.

[0053] The vehicle 1 is thus about to perform a traffic scenario action, i.e. entering the crossing by making a left-turn. The traffic scenario action will be performed when a positive decision signal has been provided, wherein the positive decision signal is provided by the following method: [0054] S1: receiving information about at least one surrounding road user 2, which information is indicative of distance d to the surrounding road user with respect to the vehicle 1 and at least one of speed v and acceleration of the surrounding road user 2; [0055] S2: calculating a value based on the received information; [0056] S3: providing the positive decision signal to perform the traffic scenario action when the calculated value is fulfilling a predetermined condition, wherein the value is calculated based on an assumption that the surrounding road user 2 will react on the traffic scenario action by changing its acceleration.

[0057] In the embodiment shown in FIG. 2, the value is further calculated based on the assumption that the surrounding road user will react on the traffic scenario action by changing its acceleration after a reaction time t.sub.r. This is indicated in FIG. 2 by the distance d.sub.r which corresponds to the distance the surrounding road user 2 will move towards the crossing until it starts to brake in order to avoid e.g. a collision with the vehicle 1. The distance d.sub.b in FIG. 2 defines the braking distance for stopping before the crossing.

[0058] By use of the above mentioned method, it can be calculated how hard the surrounding road user would have to brake to stop before the crossing. If it is desired for the surrounding road user 2 to stop before the crossing, the surrounding road user 2 may have approximately the distance d-d.sub.c to stop. A correction may be performed for example in order to compensate for that the vehicle 1 is located a certain distance within the crossing, and/or compensate for that the vehicle 1 has a certain width.

[0059] By use of the above mentioned information, the following equation may be provided:

$d-d_c>d_b+d_r$

$d>d_c+\frac{v^2}{-2a}+v{t}_r$

$a<-\frac{v^2}{2\left(d-d_c-v{t}_r\right)}$

[0060] Consequently, the distance d-d.sub.c should be larger than the distance d.sub.b + d.sub.r. Further, the distance d.sub.r may be calculated as the speed v times the reaction time t.sub.r. The braking distance d.sub.b may be calculated as the speed v in square divided by the braking acceleration a times 2. By use of this equation, a value a can thus be calculated which corresponds to the required acceleration for the surrounding road user 2 to be able to stop before the crossing. This means that the surrounding road user 2 would have to brake with at least an acceleration a to stop before the crossing. This required acceleration a can then be compared to a threshold value to decide if the positive decision signal should be provided to allow the traffic scenario action to be performed by the vehicle 1, i.e. to make the left-turn. FIG. 4 shows a graph showing the needed acceleration value, i.e. threshold values, for different distances d for a few speeds v of the surrounding road user 2 and with d.sub.c= 10 m and a reaction time t.sub.r = 1 second. More specifically, the three curves show speeds v being 50, 60 or 70 km/h. The threshold values Acc.sub.lim1 and Acc.sub.lim2 correspond to two different example threshold values, either approximately -1 m/s.sup.2 or -2 m/s.sup.2. If Acc.sub.lim1 is used, an approaching surrounding road user 2 at 50 km/h would have to be at a distance d of about 120 m or more from the vehicle 1 in order for the vehicle 1 to start driving into the main road section, i.e. perform the left-turn. Corresponding distances for 60 km/h and 70 km/h are about 165 m and more than 200 m. If Acc.sub.lim2 is used instead as the threshold value, i.e. a less conservative decision making, the distances needed for 50, 60 and 70 km/h are about 72, 95 and 123 m respectively. The above example shows when it is assumed that the surrounding road user 2 reacts on the traffic scenario action by changing its acceleration to an acceleration profile having a constant acceleration. A different calculation would be required if it instead was assumed that the surrounding road user 2 will react on the traffic scenario action by changing its acceleration to an acceleration profile having a variable acceleration. Such calculation may not be more complicated, but may increase the complexity of the calculation, and may require more calculations, which may take longer time to perform.

[0061] The predetermined condition is in the above thus defined by the threshold values Acc.sub.lim1 and/or Acc.sub.lim2 which are acceleration limits for the surrounding road user 2. Also other threshold values may be used for defining the predetermined condition, as long as the threshold values are indicative of an acceleration limit for the surrounding road user 2. As an example, the predetermined condition may be defined by a threshold value which corresponds to a time for the surrounding road user to stop before the crossing.

[0062] The method may further comprise an optional step S4 (indicated by the box with dashed lines in FIG. 6a) of providing a negative decision signal not to perform the traffic scenario action when the calculated value is not fulfilling the predetermined condition.

[0063] With respect to FIG. 3, FIG. 5 and FIG. 6a, another example embodiment of the present invention will be described. FIG. 3 shows a schematic view from above of a traffic scenario where a vehicle 1, which may be the truck as shown in FIG. 1, is about to change lanes and drive in to a neighbouring lane. This is indicated by the arrow pointing from the vehicle 1 into the neighbouring lane in FIG. 3, indicative of that the vehicle 1 is about to change lanes. A surrounding road user 2 which is driving in the neighbouring lane is located behind the vehicle 1 at a distance d′ and driving at a speed v.sub.t, indicated by the arrow proximate the surrounding road user 2 which is pointing in the direction towards the right in the figure. Another surrounding road user 2' is also driving in the neighbouring lane, but in front of the vehicle 1. When performing a lane change, it is assumed that the surrounding road user 2 will react on the traffic scenario action by changing its acceleration. In this embodiment, it is assumed that the surrounding road user 2 will react by changing the acceleration after a reaction time t.sub.r. The acceleration corresponds to the surrounding road user 2 braking in order not to risk colliding or coming too close to the vehicle 1. The vehicle 1 is driving at speed v.sub.e. After the braking phase of the surrounding road user 2, it is desired that a minimum gap distance is not exceeded. This gap may be based on a minimum desired time gap t.sub.g and may be calculated as v.sub.e times t.sub.g. It is in this example further assumed that the vehicle 1 will drive at constant speed through the lane change.

[0064] For the resulting gap distance to be larger than required the following equation should be fulfilled:

$d^{\prime }-t_r\left(v_t-v_e\right)=\frac{v_t+v_e}{2}\frac{v_t+v_e}{-a}+v_e\frac{v_t+v_e}{-a}>v_e{t}_g$

$d^{\prime }-t_r\left(v_t-v_e\right)-\left(\frac{v_t+v_e}{2}-v_e\right)\frac{v_t-v_e}{-a}>v_e{t}_g$

$d^{\prime }-t_r\left(v_t-v_e\right)-\left(\frac{v_t-v_e}{2}\right)\frac{v_t-v_e}{-a}>v_e{t}_g$

$d^{\prime }-t_r\left(v_t-v_e\right)-\frac{{\left(v_t-v_e\right)}^2}{-2a}>v_e{t}_g$

$d^{\prime }-t_r\left(v_t-v_e\right)-v_e{t}_g>\frac{{\left(v_t-v_e\right)}^2}{-2a}$

$a<-\frac{{\left(v_t-v_e\right)}^2}{2\left(d^{\prime }-t_r\left(v_t-v_e\right)-v_e{t}_g\right)}$

[0065] This equation provides a threshold value defining the predetermined condition, which threshold value is an acceleration limit for the surrounding road user 2. FIG. 5 shows a graph with examples for the case when v.sub.e = 70 km/h, t.sub.r = 1 second and t.sub.g = 1 second for different v.sub.t, i.e. v.sub.t is any one of 90, 110, 130 or 150 km/h.

[0066] In the shown example, two different threshold values are shown for a, Acc.sub.lim3 and Acc.sub.lim4 which are -1 m/s.sup.2 and -2 m/s.sup.2, respectively. As can be seen, the required distance d′ is very big when the relative speed is high. For the case when v.sub.t = 90 km/h, the threshold distances d′ are about 30 and 40 m. For v.sub.t = 110 km/h, the threshold distances d′ are about 60 and 90 m. For v.sub.t = 130 km/h, the threshold distances d′ are about 110 and 175 m. For v.sub.t = 150 km/h, the threshold distances d′ are about 165 and 290 m.

[0067] A similar calculation as in the above may also be performed for the other surrounding road user 2' which is located in front of the vehicle 1. However, in this case the other surrounding road user 2' may rather need to change its acceleration by increasing its speed in order to support the vehicle 1 to perform the lane change.

[0068] With respect to FIG. 6b, a flowchart of an example embodiment of a method according to the second aspect of the invention is shown. The method is a method for automatically performing a traffic scenario action of a vehicle 1, and comprises: S5: receiving a positive decision signal to perform the traffic scenario action, which positive decision signal has been provided according to the method of any one of the embodiments of the first aspect of the invention; and S6: automatically performing the traffic scenario action.

[0069] With respect to FIG. 6c, a flowchart of an example embodiment of a method according to the third aspect of the invention is shown. The method is a method for automatically avoiding performing a traffic scenario action of a vehicle 1, and comprises: S7: receiving a negative decision signal not to perform the traffic scenario action, which negative decision signal has been provided according to an embodiment of the method of the first aspect of the invention; and S8: automatically avoiding performing the traffic scenario action.

[0070] The control unit 10 as mentioned in the above may be used for performing the methods as disclosed herein. With respect to the second aspect of the invention, the control unit 10 may be configured to automatically perform the traffic scenario action by issuing a signal to e.g. a powertrain (not shown) of the vehicle 1. The issued signal to the powertrain may for example activate the powertrain so that the vehicle 1 starts moving and/or accelerates. The issued signal may also trigger a braking system and/or a steering system of the vehicle 1 to perform the traffic scenario action. In a similar manner, with respect to the third aspect of the invention, the control unit 10 may be configured to automatically avoid performing the traffic scenario action by issuing another signal to e.g. the powertrain.

[0071] The control unit 10 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control unit 10 may also, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit 10 includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device. The control unit 10 may comprise embedded hardware, sometimes with integrated software, where the hardware show close physical relationship. Examples of physical relationships are: shared casing and components mounted on one or several circuit boards. It shall be noted that the control unit 10 may be formed by one or more connected sub control units, or equivalent computer resources.

[0072] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.