Method for controlling the braking of a following vehicle of a string comprising a plurality of platooning vehicles

1. A method for a string comprising a plurality of vehicles platooning by means of vehicle-to-vehicle (V2V) communication, comprising: collecting from a plurality of sources values of operational parameters related to the operation of a first of the vehicles, determining based on the operational parameter values a plurality of values of an acceleration parameter indicative of an acceleration of the first vehicle, selecting from the acceleration parameter values an extreme value indicative of the lowest acceleration of the first vehicle, and a second of the vehicles following behind the first vehicle determining, or receiving by means of the V2V communication, the extreme value, and initiating in dependence on the extreme value a control of brakes for a braking action of the second vehicle, wherein determining the acceleration parameter values is done by the first vehicle, where the second vehicle is provided with a movement sensor for determining the distance to, velocity of and/or acceleration of a vehicle in front of the second vehicle, wherein the second vehicle, subsequently to the initiation of the control of the brakes, determining at least partly based on signals from the movement sensor whether to adjust the control of the brakes, and wherein, as soon as the first vehicle brakes hard, or is predicted to brake hard, sending the extreme value to the second vehicle, and the second vehicle immediately initiating activation of its brakes based on the received extreme value, wherein during a time lag from the braking control initiation to the resulting acceleration of the second vehicle, the second vehicle compares the acceleration of the first vehicle indicated by the extreme value, determined, or received over the V2V communication, by the second vehicle, to information based on the signals from the movement sensor, and when the information based on the signals from the movement sensor substantially agree with the extreme value, the braking is continued, and when the information based on the signals from the movement sensor disagrees with the extreme value, the braking is discontinued.

2. The method according to claim 1 , characterized in that at least one of the acceleration parameter values is indicative of a predicted acceleration of the first vehicle.

3. The method according to claim 1 , characterized in that selecting the extreme value is done by the first vehicle.

4. The method according to claim 3 , characterized by sending the extreme value by the V2V communication to the second of the vehicles following behind the first vehicle.

5. The method according to claim 1 , characterized by sending by the V2V communication the acceleration parameter values to the second of the vehicles following behind the first vehicle.

6. The method according to claim 1 , characterized in that selecting the extreme value is done by the second vehicle.

7. The method according to claim 1 , characterized in that initiating the control of the brakes comprises controlling the brakes for providing a braking force of the second vehicle which is proportional to the extreme value, or controlling the brakes for providing a braking force of the second vehicle which is at a maximum level.

8. The method according to claim 1 , characterized in that adjusting the control of the brakes comprises controlling the brakes to abort the braking action.

9. The method according claim 1 , characterized in that determining whether to adjust the control of the brakes comprises determining based on the signals from the movement sensor a further value of the acceleration parameter indicative of the acceleration of a vehicle in front of the second vehicle, and comparing the further acceleration parameter value with the extreme value.

10. The method according to claim 9 , characterized by adjusting the control of the brakes when the further acceleration parameter value is above the extreme value by more than a tolerance amount.

11. The method according to claim 10 , characterized by determining the tolerance amount at least partly based on the extreme value.

12. The method according to claim 10 , characterized in that the tolerance amount is predetermined.

13. The method according to claim 9 , characterized in that the determination whether to adjust the control of the brakes is partly based on a lapse of time from the collection of the operational parameter value based on which the extreme value is determined, to the comparison of the further acceleration parameter value with the extreme value.

14. The method according to claim 1 , where the second vehicle follows immediately behind the first vehicle.

15. The method according to claim 1 , where a third vehicle is travelling between the first and second vehicles.

16. A non-transitory computer readable medium carrying a computer program comprising program code for performing the steps of claim 1 when said program code is run on a computer.

17. A method for a string comprising a plurality of vehicles platooning by means of vehicle-to-vehicle (V2V) communication, where a primary of the vehicles is provided with a movement sensor for determining the distance to, velocity of and/or acceleration of a vehicle in front of the primary vehicle, the primary vehicle determining, or receiving by means of the V2V communication, a communicated value of an acceleration parameter indicative of an acceleration of a secondary of the vehicles, in front of the primary vehicle, and initiating in dependence on the communicated value a control of brakes for a braking action of the primary vehicle, wherein the primary vehicle, subsequently to the initiation of the control of the brakes, determining at least partly based on signals from the movement sensor whether to adjust the control of the brakes, wherein initiating the control of the brakes comprises controlling the brakes for providing a braking force of the primary vehicle which is proportional to the communicated value, or controlling the brakes for providing a braking force of the primary vehicle which is at a maximum level, wherein the primary vehicle, subsequently to the initiation of the control of the brakes, determining at least partly based on signals from the movement sensor whether to adjust the control of the brakes, and wherein, as soon as the secondary vehicle brakes hard, or is predicted to brake hard, sending the extreme value to the primary vehicle, and the primary vehicle immediately initiating activation of its brakes based on the received extreme value, wherein during a time lag from the braking control initiation to the resulting acceleration of the primary vehicle, the primary vehicle compares the acceleration of the secondary vehicle indicated by the extreme value, determined, or received over the V2V communication, by the primary vehicle, to information based on the signals from the movement sensor, and when the information based on the signals from the movement sensor substantially agree with the extreme value, the braking is continued, and when the information based on the signals from the movement sensor disagrees with the extreme value, the braking is discontinued.

18. The method according to claim 17 , characterized in that adjusting the control of the brakes comprises controlling the braking means to abort the braking action.

19. The method according to claim 17 , characterized in that determining whether to adjust the control of the brakes comprises determining based on the signals from the movement sensor a further value of the acceleration parameter indicative of the acceleration of a vehicle in front of the primary vehicle, and comparing the further acceleration parameter value with the communicated value.

20. The method according to claim 19 , characterized by adjusting the control of the brakes when the further acceleration parameter value is above the communicated value by more than a tolerance amount.

21. The method according to claim 20 , characterized by determining the tolerance amount at least partly based on the communicated value.

22. The method according to claim 20 , characterized in that the tolerance amount is predetermined.

23. The method according to any one of claim 19 , characterized in that the determination whether to adjust the control of the brakes is partly based on a lapse of time from a collection of an operational parameter value based on which the communicated value is determined, to the comparison of the further acceleration parameter value with the communicated value.

24. The method according to claim 17 , where the primary vehicle follows immediately behind the secondary vehicle.

25. The method according to claim 17 , where a third vehicle is travelling between the primary and secondary vehicles.