METHOD AND RELATED SYSTEM FOR ESTIMATING THE INTERNATIONAL ROUGHNESS INDEX OF A ROAD SEGMENT

Abstract

The invention concerns a method for estimating an International Roughness Index (IRI) of a road or road segment. comprising a preliminary step (1) and an International Roughness Index estimation step (10). The preliminary step (1) comprises collecting (2) values of vehicle tire damping and stiffness coefficients (C.sub.t, K.sub.t) and collecting (3) vehicle vertical acceleration values (Az.sub.vehicle) measured on vehicles driven at a constant speed along road segments to which known international roughness index values or known road profiles (profile.sub.r) are associated, as well as vehicle geo-referencing data and speed data indicative of the given constant speed associated with the measured vertical acceleration values (Az.sub.vehicle).

Claims

1-13. (canceled)

14. A method for estimating an International Roughness Index (IRI) of a road or road segment, the method comprising: in a preliminary stage: collecting values of vehicle tire damping and stiffness coefficients of one or more tires; collecting: first vehicle vertical acceleration values measured on one or more motor vehicles driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or known first road profiles are associated; first vehicle geo-referencing data associated with the measured first vertical acceleration values; and first vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values; determining second road profiles based on the values of vehicle tire damping and stiffness coefficients, the first vehicle geo-referencing data, the first vehicle speed data, and the first vehicle vertical acceleration values; determining second vehicle vertical acceleration values based on the second road profiles, second vehicle geo-referencing data of the second vertical acceleration values, second vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values, and the values of vehicle tire damping and stiffness coefficients; determining values of vehicle suspension damping and stiffness coefficients of one or more suspensions of one or more vehicles; determining first and second root mean square values of the first and second vehicle vertical acceleration values, respectively; determining, based on the known IRI values or the first road profiles on the second root mean square values of the second vehicle vertical acceleration values, on the second vehicle geo-referencing data and on second vehicle speed data, one or more vehicle transfer functions mathematically relating the second root mean square values of the second vehicle vertical acceleration values and the IRI values at the one or more given constant speeds; and in an IRI estimation stage: acquiring third vehicle vertical acceleration values measured on a given motor vehicle driven at a driving speed on a given road or road segment, third vehicle geo-referencing data associated with the third vehicle vertical acceleration values, and third vehicle speed data indicative of the given driving speed of the motor vehicle; computing third root mean square values of the third vehicle vertical acceleration values; and estimating an IRI value of the given road or road segment based on one or more vehicle transfer functions determined in the preliminary stage and on the third root mean square values of the third vehicle vertical acceleration values and the associated third vehicle geo-referencing data and the third vehicle speed data.

15. The method of claim 14, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to one or more motor vehicles of one and the same given vehicle type and/or of one and the same given vehicle model driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or the first road profiles are associated; and the second road profiles are specific to the given vehicle type and/or given vehicle model.

16. The method of claim 15, wherein the IRI value is estimated by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary stage.

17. The method of claim 14, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to each of one or more motor vehicles of different given vehicle types and/or of different given vehicle models; and the second road profiles are specific to each one of the given vehicle types and/or given vehicle models.

18. The method of claim 17, wherein the IRI value is estimated by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary stage.

19. The method of claim 14, wherein: the step of determining the values of vehicle suspension damping and stiffness coefficients of the one or more suspensions of the one or more vehicles comprises: determining, for test vehicle suspension damping and stiffness coefficients values of the suspensions of the vehicle inputted in the second road profiles, corresponding second vehicle vertical acceleration values; verifying if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with first acceleration profiles generated from the first vehicle vertical acceleration values; and if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining that the test vehicle damping and stiffness coefficients values of the suspensions of the vehicle are the vehicle suspension damping and stiffness coefficients; or if the second acceleration profiles generated from the second vehicle vertical acceleration values do not fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining new values for the test vehicle suspension damping and stiffness coefficients values.

20. The method of claim 14, wherein the step of determining the first and second root mean square values of the first and second vehicle vertical acceleration values, respectively comprises: computing first root mean square values of the first vehicle vertical acceleration values based on the first road profiles and with respect to a motor vehicle driven on a known road at known different speeds; determining second root mean square values of the second vehicle vertical acceleration values based on the second road profiles, the vehicle suspension damping and stiffness coefficients values and with respect to a motor vehicle driven on the same known road and at the same known different speeds; and plotting the first root mean square values of the first vehicle vertical acceleration values with respect to the second root mean square values of the second vehicle vertical acceleration values, thereby verifying if the second road profiles has been fitted well enough to match the results of the first road profiles.

21. A system for estimating an International Roughness Index (IRI) of a road or road segment, the system comprising: a respective first acquisition device installed on board and coupled to a respective vehicle bus for each of a first set of one or more first motor vehicles; a respective second acquisition device installed on board and coupled to a respective vehicle bus for each of a second set of one or more second motor vehicles; a cloud computing system remotely connected to the first and second acquisition devices and configured, in a preliminary stage, to: collect values of vehicle tire damping and stiffness coefficients of one or more tires; collect, via the one or more first acquisition devices: first vehicle vertical acceleration values measured on one or more of the first set of motor vehicles driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or known first road profiles are associated; first vehicle geo-referencing data associated with the measured first vertical acceleration values; and first vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values; determine second road profiles based on the values of vehicle tire damping and stiffness coefficients, the first vehicle geo-referencing data, the first vehicle speed data, and the first vehicle vertical acceleration values; determine second vehicle vertical acceleration values based on the second road profiles, second vehicle geo-referencing data of the second vertical acceleration values, second vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values, and the values of vehicle tire damping and stiffness coefficients; determine values of vehicle suspension damping and stiffness coefficients of one or more suspensions of one or more vehicles; determine first and second root mean square values of the first and second vehicle vertical acceleration values, respectively; and determine, based on the known IRI values or the first road profiles on the second root mean square values of the second vehicle vertical acceleration values, on the second vehicle geo-referencing data and on second vehicle speed data, one or more vehicle transfer functions mathematically relating the second root mean square values of the second vehicle vertical acceleration values and the IRI values at the one or more given constant speeds; the cloud computing system further configured, in an IRI estimation stage, to: acquire, via the one or more second acquisition devices, third vehicle vertical acceleration values measured on a given motor vehicle driven at a driving speed on a given road or road segment, third vehicle geo-referencing data associated with the third vehicle vertical acceleration values, and third vehicle speed data indicative of the given driving speed of the motor vehicle; compute third root mean square values of the third vehicle vertical acceleration values; and estimate an IRI value of the given road or road segment based on one or more vehicle transfer functions determined in the preliminary stage and on the third root mean square values of the third vehicle vertical acceleration values and the associated third vehicle geo-referencing data and the third vehicle speed data.

22. The system of claim 21, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to one or more motor vehicles of one and the same given vehicle type and/or of one and the same given vehicle model driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or the first road profiles are associated; and the second road profiles are specific to the given vehicle type and/or given vehicle model.

23. The system of claim 22, wherein the IRI value is estimated by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary stage.

24. The system of claim 21, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to each of one or more motor vehicles of different given vehicle types and/or of different given vehicle models; and the second road profiles are specific to each one of the given vehicle types and/or given vehicle models.

25. The system of claim 24, wherein the IRI value is estimated by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary stage.

26. The system of claim 21, wherein: the cloud computing system is configured to determine the values of vehicle suspension damping and stiffness coefficients of the one or more suspensions of the one or more vehicles by: determining, for test vehicle suspension damping and stiffness coefficients values of the suspensions of the vehicle inputted in the second road profiles, corresponding second vehicle vertical acceleration values; verifying if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with first acceleration profiles generated from the first vehicle vertical acceleration values; and if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining that the test vehicle damping and stiffness coefficients values of the suspensions of the vehicle are the vehicle suspension damping and stiffness coefficients; or if the second acceleration profiles generated from the second vehicle vertical acceleration values do not fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining new values for the test vehicle suspension damping and stiffness coefficients values.

27. The system of claim 21, wherein the cloud computing system is configured to determine the first and second root mean square values of the first and second vehicle vertical acceleration values, respectively, by: computing first root mean square values of the first vehicle vertical acceleration values based on the first road profiles and with respect to a motor vehicle driven on a known road at known different speeds; determining second root mean square values of the second vehicle vertical acceleration values based on the second road profiles, the vehicle suspension damping and stiffness coefficients values and with respect to a motor vehicle driven on the same known road and at the same known different speeds; and plotting the first root mean square values of the first vehicle vertical acceleration values with respect to the second root mean square values of the second vehicle vertical acceleration values, thereby verifying if the second road profiles has been fitted well enough to match the results of the first road profiles.

28. A system for estimating an International Roughness Index (IRI) of a road or road segment, the system comprising: a respective first acquisition device installed on board and coupled to a respective vehicle bus for each of a first set of one or more first motor vehicles; a respective second acquisition device installed on board and coupled to a respective vehicle bus for each of a second set of one or more second motor vehicles; a cloud computing system remotely connected to the first acquisition devices and configured, in a preliminary stage, to: collect values of vehicle tire damping and stiffness coefficients of one or more tires; collect, via the one or more first acquisition devices: first vehicle vertical acceleration values measured on one or more of the first set of motor vehicles driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or known first road profiles are associated; first vehicle geo-referencing data associated with the measured first vertical acceleration values; and first vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values; determine second road profiles based on the values of vehicle tire damping and stiffness coefficients, the first vehicle geo-referencing data, the first vehicle speed data, and the first vehicle vertical acceleration values; determine second vehicle vertical acceleration values based on the second road profiles, second vehicle geo-referencing data of the second vertical acceleration values, second vehicle speed data indicative of the one or more given constant speeds associated with the measured first vertical acceleration values, and the values of vehicle tire damping and stiffness coefficients; determine values of vehicle suspension damping and stiffness coefficients of one or more suspensions of one or more vehicles; determine first and second root mean square values of the first and second vehicle vertical acceleration values, respectively; and determine, based on the known IRI values or the first road profiles on the second root mean square values of the second vehicle vertical acceleration values, on the second vehicle geo-referencing data and on second vehicle speed data, one or more vehicle transfer functions mathematically relating the second root mean square values of the second vehicle vertical acceleration values and the IRI values at the one or more given constant speeds; for each of the one or more second motor vehicles, a respective electronic control unit installed on board thereof and connected to the respective second acquisition device, wherein each respective electronic control unit is configured, in an IRI estimation stage, to: acquire, via the respective second acquisition device, third vehicle vertical acceleration values measured on a given motor vehicle driven at a driving speed on a given road or road segment, third vehicle geo-referencing data associated with the third vehicle vertical acceleration values, and third vehicle speed data indicative of the given driving speed of the motor vehicle; compute third root mean square values of the third vehicle vertical acceleration values; and estimate an IRI value of the given road or road segment based on one or more vehicle transfer functions determined in the preliminary stage and on the third root mean square values of the third vehicle vertical acceleration values and the associated third vehicle geo-referencing data and the third vehicle speed data.

29. The system of claim 28, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to one or more motor vehicles of one and the same given vehicle type and/or of one and the same given vehicle model driven at one or more given constant speeds along one or more roads or road segments to which known IRI values or the first road profiles are associated; and the second road profiles are specific to the given vehicle type and/or given vehicle model.

30. The system of claim 29, wherein the IRI value is estimated by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary stage.

31. The system of claim 28, wherein: the first vehicle vertical acceleration values, the first vehicle geo-referencing data, and the first vehicle speed data are collected with respect to each of one or more motor vehicles of different given vehicle types and/or of different given vehicle models; and the second road profiles are specific to each one of the given vehicle types and/or given vehicle models.

32. The system of claim 28, wherein: the cloud computing system is configured to determine the values of vehicle suspension damping and stiffness coefficients of the one or more suspensions of the one or more vehicles by: determining, for test vehicle suspension damping and stiffness coefficients values of the suspensions of the vehicle inputted in the second road profiles, corresponding second vehicle vertical acceleration values; verifying if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with first acceleration profiles generated from the first vehicle vertical acceleration values; and if the second acceleration profiles generated from the second vehicle vertical acceleration values fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining that the test vehicle damping and stiffness coefficients values of the suspensions of the vehicle are the vehicle suspension damping and stiffness coefficients; or if the second acceleration profiles generated from the second vehicle vertical acceleration values do not fit with the first acceleration profiles generated from the first vehicle vertical acceleration values, determining new values for the test vehicle suspension damping and stiffness coefficients values.

33. The system of claim 28, wherein the cloud computing system is configured to determine the first and second root mean square values of the first and second vehicle vertical acceleration values, respectively, by: computing first root mean square values of the first vehicle vertical acceleration values based on the first road profiles and with respect to a motor vehicle driven on a known road at known different speeds; determining second root mean square values of the second vehicle vertical acceleration values based on the second road profiles, the vehicle suspension damping and stiffness coefficients values and with respect to a motor vehicle driven on the same known road and at the same known different speeds; and plotting the first root mean square values of the first vehicle vertical acceleration values with respect to the second root mean square values of the second vehicle vertical acceleration values, thereby verifying if the second road profiles has been fitted well enough to match the results of the first road profiles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] For a better understanding of the present invention, preferred embodiments, which are intended purely by way of non-limiting examples, will now be described with reference to the attached drawings (all not to scale), where:

[0036] FIGS. 1 and 2 schematically and respectively illustrate a preliminary step and an IRI estimation step of an IRI estimation method according to a preferred embodiment of the present invention.

[0037] FIG. 3 schematically illustrates a step of a preliminary step for determining parameters relative to a vehicle;

[0038] FIG. 4 schematically shows trends for vertical acceleration values according to different road profiles;

[0039] FIG. 5 schematically illustrates a step of a preliminary step for validating parameters relative to a vehicle;

[0040] FIG. 6 schematically shows a plot correlating root mean square values of respective vehicle vertical acceleration values obtained according to a real and a digitized road profiles;

[0041] FIG. 7 schematically shows plots correlating IRI values with root mean square values of vehicle vertical acceleration values at different constant vehicle speeds; and

[0042] FIGS. 8-10 schematically illustrate preferred embodiments of an IRI estimation system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0043] The present invention will now be described in detail with reference to the attached figures to allow a skilled person to make and use it. Various modifications to the embodiments described will be immediately apparent to a skilled person and the generic principles described can be applied to other embodiments and applications without thereby departing from the scope of the present invention, as defined in the attached claims. Therefore, the present invention should not be considered limited to the embodiments described and illustrated herein, but should be accorded the broadest scope of protection consistent with the described and claimed features.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning commonly used by persons of ordinary experience in the field pertaining to the present invention. In the event of a conflict, this description, including the definitions provided, will be binding. Furthermore, the examples are provided for illustrative purposes only and as such should not be regarded as limiting.

[0045] In particular, the block diagrams included in the attached figures and described below are not intended as a representation of the structural characteristics, or constructive limitations, but must be interpreted as a representation of functional characteristics, i.e. intrinsic properties of the devices and defined by the effects obtained or functional limitations and which can be implemented in different ways, therefore in order to protect the functionality of the same (possibility of functioning).

[0046] In order to facilitate the understanding of the embodiments described herein, reference will be made to some specific embodiments and a specific language will be used to describe them. The terminology used herein has the purpose of describing only particular embodiments, and is not intended to limit the scope of the present invention.

[0047] The present invention concerns a method for estimating the International Roughness Index (IRI), in particular as a function of physical quantities relating to the motion of a vehicle, for instance the vertical accelerations, and to the vehicle itself, for instance the damping and stiffness coefficients of the suspensions of the vehicle and the tires mounted on the vehicle.

[0048] With reference to FIGS. 1 and 2, the method according to the present invention comprises a preliminary step 1 and an IRI estimation step 10. Furthermore, hereinafter reference to a motor vehicle such as one or more cars and/or buses and/or trucks and/or motorbikes, etcetera, fitted with internal combustion engines and/or of the hybrid and/or electric type(s), will be made.

[0049] In particular, FIG. 1 schematically illustrates the preliminary step 1 of the method for estimating the IRI according to the present invention. In detail, the preliminary step 1 comprises: [0050] collecting (block 2) values of vehicle tire damping and stiffness coefficients C.sub.t, K.sub.t of one or more tires (not shown) of one or more motor vehicles; [0051] collecting (block 3): [0052] a) first vehicle vertical acceleration values Az.sub.vehicle measured on one or more motor vehicles driven at one or more given constant speeds along one or more roads or road segments to which known international roughness index values or known first road profiles profile.sub.r are associated; [0053] b) first vehicle geo-referencing data associated with the measured first vertical acceleration values Az.sub.vehicle; and [0054] c) first vehicle speed data indicative of the given constant speed (s) associated with the measured first vertical acceleration values Az.sub.vehicle; and [0055] determining (block 4) second road profiles profile.sub.d based on the first values of vehicle tire damping and stiffness coefficients C.sub.t, K.sub.t, the first vehicle geo-referencing data, the first vehicle speed data, and the first vehicle vertical acceleration values Az.sub.vehicle,

[0056] The preliminary step 1 further comprises: [0057] determining (block 5) second vehicle vertical acceleration values Az.sub.output?f (c, k) based on the second road profiles profile.sub.d, second vehicle geo-referencing data of the second vertical acceleration values Az.sub.output?f(c, k), second vehicle speed data indicative of the given constant speed (s) associated with the measured first vertical acceleration values Az.sub.vehicle, and the values of vehicle tire damping and stiffness coefficients C.sub.t, K.sub.t; [0058] determining (block 6) values of vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s of one or more suspensions of one or more vehicles; [0059] determining (block 7) first and second root mean square values of the first and second vehicle vertical acceleration values Az.sub.vehicle, Az.sub.output?f(c, k), respectively; and [0060] determining (block 8), based on the known International Roughness Index values or the first road profiles profile.sub.r, on the second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f (c, k), on the second vehicle geo-referencing data and on second vehicle speed data, one or more vehicle transfer functions mathematically relating the second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f(c, k) and the International Roughness Index values at the given constant speed (s),

[0061] FIG. 2 schematically illustrates the IRI estimation step 10 of the method for estimating the IRI according to the present invention. In particular, the IRI estimation step 10 comprises: [0062] acquiring (block 11) third vehicle vertical acceleration values Az measured on a given motor vehicle driven at a driving speed on a given road or road segment, third vehicle geo-referencing data associated with the third vehicle vertical acceleration values Az and third vehicle speed data indicative of the given driving speed of the motor vehicle; [0063] computing (block 12) third root mean square values of the third vehicle vertical acceleration values Az; and [0064] estimating an International Roughness Index (IRI) value (block 13) of the given road or road segment based on one or more vehicle transfer functions determined in the preliminary step 1 and on the third root mean square values of the third vehicle vertical acceleration values Az and the associated third vehicle geo-referencing data and the third vehicle speed data.

[0065] According to an aspect of the present invention, the third vehicle geo-referencing data of the given motor vehicle are namely data indicative of 2D/3D position, e.g. GPS position, of the given motor vehicle.

[0066] According to an aspect of the present invention, the first vehicle vertical acceleration values Az.sub.vehicle, the first vehicle geo-referencing data, and the first vehicle speed data are collected in steps a), b) and c) in respect of one or more motor vehicles of one and the same given vehicle type and/or of one and the same given vehicle model driven at one or more given constant speeds along one or more roads or road segments for which International Roughness Index values or the first road profiles profile.sub.r are known; furthermore, the second road profiles profile.sub.d are specific to said given vehicle type and/or model.

[0067] According to another aspect of the present invention, the first vehicle vertical acceleration values Az.sub.vehicle, the first vehicle geo-referencing data, and the first vehicle speed data are collected in steps a), b) and c) in respect of each one of one or more motor vehicles of different given vehicle types and/or of different given vehicle models; furthermore, the second road profiles profile.sub.d are specific to each one of said given vehicle types and/or models.

[0068] Therefore, according to an aspect of the present invention, the International Roughness Index values is estimated (block 13) by using a vehicle transfer function specific to vehicle type/model of the given motor vehicle determined in the preliminary step 1.

[0069] Once again with reference to FIG. 1, in the preliminary step 1, the vehicle tire damping and stiffness coefficients C.sub.t, K.sub.t are determined through tire tests, such as, for example, dedicated deflection tests.

[0070] Furthermore, according to an aspect of the present invention, the step of collecting (block 3) first vehicle vertical acceleration values AZ.sub.vehicle, first vehicle geo-referencing data and first vehicle speed data include a vehicle telemetry data acquisition, wherein vehicles are conveniently equipped with a data logger unit acquiring the first vehicle vertical accelerations Az.sub.vehicle and the first vehicle geo-referencing data as GPS positions of the vehicles with predefined acquisition frequencies. Furthermore, the telemetry data are automatically transmitted to a remote computing system (e.g., a cloud computing system) via a wireless connection (e.g., based on 2G, 3G, 4G or 5G cellular technology). In particular, the acquisition frequency for the first vehicle geo-referencing data is for instance greater than 1 Hz. Furthermore, in order to determine the first vehicle vertical acceleration values Az.sub.vehicle, the vehicle is driven through bumps of known geometry (i.e., according, for instance, to the first road profile profile.sub.r) at low speed (e.g., up to 40 km/h); in further detail the acquisition frequency of the first vehicle vertical acceleration values Az.sub.vehicle is higher than or equal to 10 Hz. Additionally, a predefined time period (e.g., of three months) can be conveniently considered for the vehicle telemetry data acquisition, wherein said predefined time period preferably includes the date of measurement of the IRI values.

[0071] According to an aspect of the invention, in the preliminary step 1, here the IRI values related to a road are determined according to a corresponding first road profile profile.sub.r, the latter being determined according to standardized procedures; for example, the first road profile profile.sub.r is determined by interpolating previously measured values of vertical accelerations, determined according to certain conditions (e.g., low speed and with a predetermined acquisition frequency) specific to vehicle type/model of given motor vehicle.

[0072] According to a further aspect of the present invention, GPS is used for positioning the vehicles on the road where the measurements are carried out either in the preliminary step 1and in the IRI estimation step 10.

[0073] With reference to FIG. 1, in the preliminary step 1, the step of determining (block 5) the second vehicle vertical acceleration values Az.sub.output?f(c, k) comprises determining: [0074] fourth vehicle vertical acceleration values Az.sub.output which are the acceleration values outputted by the second road profiles profile.sub.d when inputted with the values of vehicle tire damping and stiffness coefficients C.sub.t, K.sub.t; and [0075] a vehicle vertical acceleration function f(c, k) depending on parameters c and k.

[0076] In particular, parameters c and k are vehicle suspension damping and stiffness coefficients values of one or more suspensions (not shown) of the considered vehicle. Thus, the output of the second road profiles profile.sub.d (which are values of vehicle vertical accelerations) directly depends on the values of the vehicle suspension damping and stiffness coefficients c, k of the one or more suspensions of the considered motor vehicle.

[0077] With reference to FIG. 3, the step of determining (block 6) the values of vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s of the one or more suspensions of the one or more vehicles comprises: [0078] determining (block 21), for test vehicle suspension damping and stiffness coefficients values c.sub.0, k.sub.0 of the suspensions of the vehicle inputted in the second road profiles profile.sub.d, corresponding second vehicle vertical acceleration values Az.sub.output?f(c, k), also referred to as Az.sub.output?f (c.sub.0, k.sub.0); and [0079] verifying (block 22) if the second acceleration profiles generated from the second vehicle vertical acceleration values Az.sub.output?f (c.sub.0, k.sub.0) fit with first acceleration profiles generated from the first vehicle vertical acceleration values Az.sub.vehicle,

[0080] Furthermore, the step of determining (block 6) the values of vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s of the one or more suspensions of the one or more vehicles further comprises: [0081] if the second acceleration profiles generated from the second vehicle vertical acceleration values Az.sub.output?f (c.sub.0, k.sub.0) fit with the first acceleration profiles generated from the first vehicle vertical acceleration values Az.sub.vehicle, determining (block 23) that the test vehicle damping and stiffness coefficients values c.sub.0, k.sub.0 of the suspensions of the vehicle are the vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s; or [0082] if the second acceleration profiles generated from the second vehicle vertical acceleration values Az.sub.output?f(c.sub.0, k.sub.0) do not fit with the first acceleration profiles generated from the first vehicle vertical acceleration values Az.sub.vehicle, determining (block 24) new values for the test vehicle suspension damping and stiffness coefficients values c.sub.0, k.sub.0.

[0083] Thus, according to an aspect of the present invention, the steps of determining (block 21) and verifying (block 22) are repeated until the test vehicle damping and stiffness coefficients values c.sub.0, k.sub.0 of the suspensions of the vehicle fulfil the requirement of the step of verifying (block 22) and, thus, can be defined as the vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s.

[0084] At the end of the step of determining (block 6) the values of vehicle suspension damping and stiffness coefficients C.sub.s, K.sub.s of the one or more suspensions of the one or more vehicles are determined as an output of the second road profile profile.sub.d.

[0085] FIG. 4 schematically shows examples of first and second acceleration profiles generated from the first and the second vehicle vertical acceleration values Az.sub.vehicle, Az.sub.output?f(c, k), wherein c and k are equal to the vehicle suspension damping and stiffness coefficients values C.sub.s, K.sub.s.

[0086] Furthermore, with reference to FIG. 5, in the preliminary step 1, the step of determining (block 7) the first and second root mean square values of the first and second vehicle vertical acceleration values Az.sub.vehicle, Az.sub.output?f(c, k), respectively comprises: [0087] computing (block 31) first root mean square values of the first vehicle vertical acceleration values Az.sub.vehicle based on the first road profiles profile.sub.r and in respect of a motor vehicle driven on a known road at known different speeds; [0088] determining (block 32) second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f(c, k) based on the second road profiles profile.sub.d, the vehicle suspension damping and stiffness coefficients values C.sub.s, K.sub.s and in respect to a motor vehicle driven on the same known road and at the same known different speeds; and [0089] plotting (block 33) the first root mean square values of the first vehicle vertical acceleration values Az.sub.vehicle with respect to the second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f(c, k), hereinafter also referred to as Az.sub.output?f(C.sub.s, K.sub.s), thereby verifying if the second road profiles profile.sub.d has been fitted well enough to match the results of the first road profiles profile.sub.r.

[0090] In particular, the step of plotting (block 33) is carried out by plotting the first RMSVA of the first vehicle vertical acceleration values Az.sub.vehicle with respect to the second RMSVA of the second vehicle vertical acceleration values Az.sub.output?f (C.sub.s, K.sub.s) along with known IRI values of the considered road. FIG. 6 shows the plot obtained through the step of plotting (block 33) carried out by plotting the first RMSVA of the first vehicle vertical acceleration values Az.sub.vehicle, filtered at 1.5 Hz, with respect to the second RMSVA of the second vehicle vertical acceleration values Az.sub.output?f(C.sub.s, K.sub.s). As it can be seen in FIG. 6, different velocities are considered.

[0091] Furthermore, in the preliminary step 1, determining (block 8), based on the known International Roughness Index values or the first road profiles profile.sub.r, on the second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f(c, k), on the second vehicle geo-referencing data and on second vehicle speed data, one or more vehicle transfer functions mathematically relating the second root mean square values of the second vehicle vertical acceleration values Az.sub.output?f(c, k) and the International Roughness Index values at the given constant speed (s) comprises identifying a related mathematical correlation between the IRI values and the second RMSVA of the second vehicle vertical acceleration values Az.sub.output?f(C.sub.s, K.sub.s), whereby a vehicle transfer function IRI=(RMSVA, speed) is determined. In this respect, FIG. 7 shows examples of IRI-RMSVA graphs at different constant vehicle speeds, wherein the IRI values at different constant vehicle speeds are plotted, and the second RMSVA determined from the second vehicle vertical acceleration values Az.sub.output?f(C.sub.s, K.sub.s) are plotted; in particular, an example of a transfer function shown in FIG. 7 is the following:

[00001]$\mathrm{IRI}=1.521+8.152.Math.\mathrm{RMSVA}-0.035.Math.v-0.3403.Math.{\mathrm{RMSVA}}^{{}_{}2}-0.044.Math.\mathrm{RMSVA}.Math.v+1.98.Math.{10}^{-4}.Math.v^{{}_{}2}$

wherein v denotes the vehicle speed.

[0092] Again with reference to FIG. 2, in the IRI estimation step 10 and regarding the third vehicle vertical acceleration values Az, the step of estimating an International Roughness Index value (block 13) of the given road or road segment based on one or more vehicle transfer functions determined in the preliminary step 1 and on the third root mean square values of the third vehicle vertical acceleration values Az and the associated third vehicle geo-referencing data and the third vehicle speed data is carried out by performing an inverse calculation. In fact, once at least one transfer function is determined in the preliminary step 1, the third root mean square values determined from the third vehicle vertical acceleration values Az and the driving speed v of a given vehicle on a generic road are known, it is possible to calculate an estimated IRI value.

[0093] The present invention concerns also a system designed to carry out the above IRI estimation method. In this respect, FIG. 8 schematically illustrates, by means of a block diagram, a functional architecture of an IRI estimation system 50 according to a preferred embodiment of the present invention.

[0094] In particular, the IRI estimation system 50 includes an acquisition device 51 that is: [0095] installed on board a motor vehicle (not shown in FIG. 8), such as a car or bus or truck or motorbike, etc., that is fitted with an internal combustion engine or of the hybrid/electric type; [0096] coupled to a vehicle bus 60 (e.g. based upon a standard Controller Area Network, CAN, bus) of said motor vehicle; and [0097] configured to acquire, from said vehicle bus 60, vehicle vertical accelerations and vehicle geo-referencing and speed data.

[0098] According to a preferred embodiment of the present invention, a respective acquisition device 51 is installed on board: [0099] each motor vehicle used to carry out the preliminary step 1 to acquire, from a respective vehicle bus 60 of said motor vehicle, the first and the second vehicle vertical acceleration values Az.sub.vehicle, Az.sub.output?f(c, k) and the first and second vehicle geo-referencing and the first and second vehicle speed data; and [0100] each given motor vehicle involved in the IRI estimation step 10 to acquire, from a respective vehicle bus 60 of said given motor vehicle, the third vehicle vertical acceleration values Az and the third vehicle geo-referencing and speed data.

[0101] Additionally, the IRI estimation system 50 further includes processing means 52 connected, in a wired or wireless fashion, to the acquisition device (s) 51 to receive therefrom the first, second and third vehicle vertical acceleration values Az.sub.vehicle, Az.sub.output?f (C, k), Az and the first, second and third vehicle geo-referencing and the first, second and third vehicle speed data, and programmed to: [0102] compute the first and the second root mean square values Az.sub.vehicle, Az.sub.output?f(c, k) and determine (block 8) the vehicle transfer function (s); and [0103] compute the third root mean square values and estimate the IRI value (s) (block 13).

[0104] FIGS. 9 and 10 schematically illustrate further preferred embodiments for implementing the processing means 52 of the system 50 of FIG. 8.

[0105] In particular, with reference to FIG. 9, in a first preferred embodiment (denoted as a whole by 70), the processing means 52 are implemented/carried out by means of a cloud computing system 72 that is wirelessly and remotely connected to the acquisition device (s) 51 (e.g., via one or more cellular technologies, such as GSM, GPRS, EDGE, HSPA, UMTS, LTE, LTE Advanced, 5G, etc.), and that is conveniently used to perform both the preliminary step 1 and the IRI estimation step 10.

[0106] Instead, with reference to FIG. 10, in a second preferred embodiment (denoted as a whole by 100), the processing means 52 are implemented/carried out by means of an (automotive) Electronic Control Unit (ECU) 102 installed on board a motor vehicle 110, wherein said ECU 102 may conveniently be an ECU specifically dedicated to IRI estimation, or an ECU dedicated to several tasks including also IRI estimation.

[0107] Preferably, the cloud computing system 72 is used to carry out the preliminary step 1, whereas the ECU 102 is used to perform the IRI estimation step 10. In particular, a respective ECU 102 can be conveniently installed on board each given motor vehicle 110 involved in the IRI estimation step 10 to acquire, from the respective acquisition device 51, the second vehicle vertical acceleration values and the second vehicle geo-referencing and speed data.

[0108] From the foregoing, the technical advantages and the innovative features of the present invention are immediately clear to those skilled in the art.

[0109] In particular, the present method allows to exploit the vehicle vertical acceleration values at given constant speed to measure preliminary IRI values on the driven roads with a frequency higher than the normal common methods used in the roads measuring procedures.

[0110] Furthermore, the present method have a wider and more frequent measuring network that would allow roads management companies to prioritize more accurate measurements in specific road segments.

[0111] Additionally, the present method allows to implement a faster and easier quantification of roughness of road pavements and, in particular, an IRI-like estimation, which are easier to perform and can be carried out more frequently than traditional IRI measurements

[0112] In conclusion, it is clear that numerous modifications and variants can be made to the present invention, which fall within the scope of the invention as defined in the attached claims.