Method ANF system for operating a detection device

Abstract

Method and system (1) for operating a detection device (4) fixed on an inner surface (5) of a tyre (3) to acquire a signal (S) representative of a motion of a portion (30) of the tyre (3), the system (1) comprising the detection device (4) and a processing unit (8) operatively connected to the detection device (4) and programmed to perform the method comprising the following steps: determining a parameter (w) representative of an angular velocity of the tyre (3); determining, based on a previous passage of the detection device (4) in correspondence with a footprint (60) of the tyre (3), a reference angular position θ0 belonging to the footprint (60); determining an initial acquisition time instant (Ti) and a final acquisition time instant (Tf) of the signal (S) as a function of the parameter (w) and of respectively a predetermined initial angular acquisition position 0i included in a neighbourhood of θ0 +3 / 2π and a predetermined final angular acquisition position θf included in a neighbourhood of θ0 + 5 / 2π; starting, and subsequently stopping, acquisition of the signal (S) in an acquisition time window (TA) defined by the initial acquisition time instant (Ti) and the final acquisition time instant (Tf).

Description

[0001] DESCRIPTION

[0002] Title: METHOD ANF SYSTEM FOR OPERATING A DETECTION DEVICE

[0003] Technical field of the invention

[0004] The present invention relates to a method, and to a corresponding system, for operating a detection device fixed on an inner surface of a tyre to acquire a signal representative of a motion of a portion of the tyre.

[0005] State of the art

[0006] It is known to fix at least one detection device on an inner surface of at least one tyre to be mounted on a vehicle, in order to acquire a signal representative of the motion of a portion of the tyre during rolling.

[0007] Typically, a tyre has a substantially toroidal structure around a rotation axis thereof during operation, and comprises an equatorial plane orthogonal to the rotation axis, said equatorial plane being typically a plane of (substantial) geometrical symmetry (for example, neglecting possible minor asymmetries, such as the tread pattern and / or writings on the sidewalls and / or the internal structure).

[0008] The expression "crown portion” means a portion of the tyre arranged in correspondence with a tread band. The term "radial” is used with reference to a direction perpendicular to the rotation axis of the tyre.

[0009] The term "footprint” means the portion of the outer surface of the tread band which, during rolling of the mounted tyre subjected to a load (for example due to mounting under a vehicle), at each instant is in contact with the rolling surface.

[0010] The footprint typically has a substantially null curvature (or a substantially infinite radius of curvature), or in any case substantially assumes the conformation of the rolling surface.

[0011] The expression "footprint area” means a respective crown portion instantaneously corresponding to the footprint. The expression "passage internally to the footprint portion”, referred to the tyre portion, means an interval, expressed for example in units of time or in degrees of rotation (for example with respect to a complete rotation), in which the tyre portion, due to rotation of the tyre, is continuously located within the footprint portion of the tyre. Document US 8,424,375 B2 discloses a method for operating a sensor, on or in a tyre of a vehicle, with a first sampling frequency in a first time interval and with a second sampling frequency in a second time interval. Document EP 3 741 588 B1 discloses a method and a system for acquiring data from a sensor mounted in a tyre. Document US 8,096, 172 B2 discloses a method for wireless communication, wherein a transmission angle along a circumference of a revolution is determined, wherein a transmission time of the transmission angle is determined at least partly based on the time required to complete a revolution, and wherein a signal is transmitted wirelessly at the transmission angle and at the transmission time.

[0012] Summary of the invention

[0013] During rolling of a tyre of a vehicle caused by advancement of the vehicle, it is advantageous to acquire over time at least one signal representative of a motion of a portion of the tyre, for example an accelerometric signal, a straingauge signal, or a velocity signal. Indeed, from such signal it is possible to derive a plurality of information relating to motion conditions of the tyre, such as for example grip, slip, presence of an aquaplaning condition, etc., which are useful for safety purposes. In particular, the Applicant has observed that, within a complete rotation of the tyre, it is important to acquire said signal at least during passage of the tyre portion in correspondence with a footprint of the tyre. Indeed, it is this portion of the signal that contains the greatest amount of information extractable for the above-mentioned purposes. At the same time, technological limitations impose strict constraints on the actual possibilities of acquisition of such signal. For example, an ideal intention to acquire the signal with a desired sampling frequency (in order to acquire also the most rapid variations of motion of the tyre portion) for extended portions of the wheel rotation, ideally for the entire wheel rotation, conflicts with the need to limit consumption of electrical energy stored in accumulators or converters, for example a battery and / or an energy harvesting element, with which the detection device is typically equipped, having limited capacity, the charge or, more generally, the energy consumption of which must be preserved as much as possible over time.

[0014] In this framework, the Applicant has further observed that, although the solution of acquiring the signal substantially only during passage of the tyre portion in correspondence with the footprint, as for example described in the above- mentioned document US 8,424,375 B2, appears ideally optimal to limit battery energy consumption without precluding the possibility of acquiring the signal where desired, such acquisition localized at the passage in correspondence with the footprint entails some important issues.

[0015] Indeed, during advancement of the vehicle, a plurality of driving factors can influence the trend and therefore the speed of the vehicle, with a consequent variation, also abrupt, during acceleration or braking, of the rotation speed of the tyre, and / or with the simultaneous presence of different rotation speeds among the tyres. This leads to a high variability in the sequence of entry times of the tyre portion in correspondence with the footprint (that is, the time interval between two consecutive passages of the portion through the footprint), as well as an equally high variability in the transit times of the portion in correspondence with the footprint itself, with a consequent difficulty in managing acquisition times and pause times of the detection device.

[0016] In this context, the Applicant has therefore addressed the problem of acquiring a signal representative of the motion of a portion of a tyre in a desired manner, for example in terms of acquisition intervals with respect to the rotation of the tyre, in order to collect useful information, and at the same time in a manner robust to variations in rolling dynamics of the tyre, as well as energetically efficient.

[0017] According to the Applicant, the above-mentioned problem is solved by a method, and a corresponding system, for operating a detection device to acquire a signal representative of the motion of a portion of the tyre, capable of predicting a temporal evolution of an angular position of the detection device in order to acquire said signal during a transit of the detection device (due to rolling of the tyre) from a predetermined initial angular acquisition position, belonging to a neighbourhood of a reference angular position 90+ 3 / 2TT, to a predetermined final angular acquisition position, belonging to a neighbourhood of the reference angular position 90+ 5 / 2TT, wherein the reference angular position 90belongs to a footprint of the tyre and is determined based on a previous passage of the detection device in correspondence with the footprint.

[0018] According to one aspect, the invention relates to a method for operating a detection device fixed on an inner surface of a tyre to acquire, by means of said detection device, a signal representative of a motion of a portion of the tyre. Preferably, operating said detection device comprises, in a current time cycle, determining a parameter representative of an angular velocity of said tyre.

[0019] Preferably, operating said detection device comprises, in said current time cycle, determining, based on a previous passage of said detection device at a footprint of said tyre, a reference angular position 90belonging to said footprint of said tyre.

[0020] Preferably, operating said detection device comprises, in said current time cycle, determining an initial acquisition time instant of the signal as a function of said parameter representative of the angular velocity and of a predetermined initial angular acquisition position 0i included in a neighbourhood of 90+ 3 / 2TT.

[0021] Preferably, operating said detection device comprises, in said current time cycle, determining a final acquisition time instant of the signal as a function of said parameter representative of the angular velocity and of a predetermined final angular acquisition position 9f included in a neighbourhood of 90+ 5 / 2TT.

[0022] Preferably, operating said detection device comprises, in said current time cycle, starting, and subsequently stopping, an acquisition of said signal in an acquisition time window defined by said initial acquisition time instant and said final acquisition time instant.

[0023] According to another aspect, the invention relates to a system for operating a detection device fixed on an inner surface of a tyre to acquire, by means of said detection device, a signal representative of a motion of a portion of the tyre.

[0024] Preferably, said system comprises said detection device structured to acquire said signal.

[0025] Preferably, said system comprises a processing unit, operatively connected to said detection device, and programmed to operate said detection device in a current time cycle.

[0026] Preferably, said processing unit is programmed to, in said current time cycle, determine a parameter representative of an angular velocity of said tyre.

[0027] Preferably, said processing unit is programmed to, in said current time cycle, determine, based on a previous passage of said detection device at a footprint of said tyre, a reference angular position 90belonging to said footprint of said tyre.

[0028] Preferably, said processing unit is programmed to, in said current time cycle, determine an initial acquisition time instant of the signal as a function of said parameter representative of the angular velocity and of a predetermined initial angular acquisition position 9i included in a neighbourhood of 90+ 3 / 2TT.

[0029] Preferably, said processing unit is programmed to, in said current time cycle, determine a final acquisition time instant of the signal as a function of said parameter representative of the angular velocity and of a predetermined final angular acquisition position 9f included in a neighbourhood of 90+ 5 / 2TT.

[0030] Preferably, said processing unit is programmed to, in said current time cycle, start, and subsequently stop, an acquisition of said signal in an acquisition time window defined by said initial acquisition time instant and said final acquisition time instant.

[0031] According to the Applicant, by predetermining the initial and final angular acquisition positions in the above- mentioned respective neighbourhoods of the reference angular position plus respectively 3 / 2TT and 5 / 2TT, with the reference angular position belonging to the footprint of the tyre during a previous wheel rotation, it is possible to determine, for the subsequent wheel rotation, an acquisition time window which angularly includes, and therefore with a high degree of certainty, at least an entire passage of the detection device in correspondence with the subsequent footprint. This also applies in an autonomously adaptive manner for each wheel rotation, as a function of the respective preceding wheel rotation, thanks to the dependence of the initial and final acquisition time instants on the parameter representative of the angular velocity (which therefore allows taking into account possible variations in rotation speed) and to the belonging of the reference angular position to the footprint of the preceding wheel rotation (which therefore allows centring, from time to time, the acquisition time window predicted for a wheel rotation on the footprint of the respectively preceding wheel rotation).

[0032] In other words, the present method therefore allows synchronizing acquisition of the signal with rotation of the tyre in order to acquire the portion of the signal of interest, namely the portion comprising passage of the detection device through the footprint, in each wheel rotation based on rotation parameters of the respective preceding wheel rotation.

[0033] Without wishing to be bound by any theory, the Applicant believes that in this way it is possible to limit acquisition to the portion of the signal of interest for each wheel rotation, therefore without renouncing useful information contained in the signal, while at the same time limiting energy consumption and in an autonomously adaptive manner with respect to possible variations in rotation of the tyre.

[0034] Furthermore, the Applicant has also realized that, by setting the acquisition time window as a function of the above- mentioned predetermined initial and final angular acquisition positions, the risk of losing the above-mentioned synchronization is strongly reduced, since the identified acquisition time window is sufficiently wide to substantially necessarily include the entire passage of the detection device in correspondence with the footprint of the tyre (and therefore allowing both acquisition of the portion of the signal of interest and determination of the reference angular position belonging to the current footprint), without excessively extending acquisition outside the area of interest. The present invention, in one or more of the above-mentioned aspects, may present one or more of the following preferred features.

[0035] Preferably, said processing unit is programmed to perform any embodiment of the method of the present invention. Preferably, said method comprises starting said acquisition at said initial acquisition time instant.

[0036] Preferably, said method comprises stopping said acquisition at said final acquisition time instant.

[0037] In this way, the entire available acquisition time window is exploited.

[0038] Preferably, said neighbourhood of 90+ 3 / 2TT is a symmetric neighbourhood centred at 90+ 3 / 2TT.

[0039] Preferably, said neighbourhood of 90+ 3 / 2TT has an angular width less than or equal to TT radians, more preferably less than or equal to 2 / 3TT radians.

[0040] Preferably, said neighbourhood of 90+ 5 / 2TT is a symmetric neighbourhood centred at 90+ 5 / 2TT.

[0041] Preferably, said neighbourhood of 90+ 5 / 2TT has an angular width less than or equal to TT radians, more preferably less than or equal to 2 / 3TT radians.

[0042] According to the Applicant, one or more of the above-mentioned symmetry and width features referred to the neighbourhoods contribute to improving the probability of acquiring the signal in correspondence with the footprint and / or reduce the risk of loss of synchronization of the acquisition with rotation of the tyre.

[0043] Preferably, said initial angular acquisition position coincides with 90+ 3 / 2TT.

[0044] Preferably, said final angular acquisition position coincides with 90+ 5 / 2TT.

[0045] The Applicant has realized that such angular positions coinciding with the above-mentioned values are particularly suitable for identifying an angular rotation portion within which to perform acquisition of the signal for the purpose of improving the probability of acquiring, at each wheel rotation, the signal at least during passage of the detection device in correspondence with the footprint and / or for the purpose of reducing the risk of loss of synchronization between acquisition and rotation.

[0046] Preferably, said detection device is fixed to said inner surface in correspondence of a crown portion of said tyre. Preferably, said portion of said tyre coincides with said crown portion of the tyre. In other words, said signal is representative of a motion of said crown portion. In other words, the tyre portion is preferably a crown portion of the tyre. In this way, the acquired signal is particularly useful for the purposes described above.

[0047] Preferably, said reference angular position coincides with an angular position of a centre, more preferably a geometrical centre, of a footprint area of said tyre. In this way, definition of the angular acquisition region (from which the acquisition time window derives) is particularly rational and advantageous for the purpose of a simple subdivision of the wheel rotation into the acquisition time window (and into other time windows as described below). Preferably, said signal is an accelerometric signal representative of at least one component of an acceleration, more preferably linear, experienced by said portion of said tyre.

[0048] In one embodiment, said signal is a velocity signal (or a displacement / deformation signal) representative of at least one component (axial, radial and / or tangential) of a linear velocity (or of a displacement / deformation) of said portion (of crown) of said tyre.

[0049] Preferably, said detection device comprises at least one sensor suitable to detect an accelerometric signal (or a velocity or displacement / deformation signal) representative of at least one component (up to three components) of an acceleration (or of a velocity or of a displacement / deformation), more preferably linear, experienced by said crown portion of said tyre.

[0050] Preferably, said at least one acceleration component is selected from the group: axial component, radial component, and tangential component.

[0051] Preferably, said at least one acceleration component is the radial component. The Applicant has ascertained that such acceleration component is particularly suitable for identifying passage in correspondence with the footprint of the detection device, to the advantage of precision and / or reliability of operation of the detection device in synchrony with rotation of the tyre. Moreover, such acceleration component has proven to be the most significant in terms of information content relating to rolling conditions of the tyre.

[0052] Preferably, operating said detection device comprises determining a further parameter representative of an angular acceleration of said tyre as a function of said parameter representative of the angular velocity, more preferably as a function of a variation over time of said parameter. Preferably, determining said initial acquisition time instant and determining said final acquisition time instant are performed also as a function of said further parameter. In this way, precision and / or reliability are increased.

[0053] Preferably, determining said initial acquisition time instant and determining said final acquisition time instant are performed as a function of a time law of a motion imparted to said detection device by rolling of the tyre. For example, said time law identifies a uniformly accelerated circular motion. Use of such time law has proven to be particularly suitable for the present invention for the purposes of increased precision and / or reliability in determining the time instants at which the detection device is expected to assume the given predetermined angular position. Preferably, said parameter representative of the angular velocity coincides with said angular velocity of said tyre. Alternatively, the parameter representative of the angular velocity may comprise a rotation period of said tyre.

[0054] Preferably, said further parameter representative of the angular acceleration coincides with said angular acceleration of said tyre.

[0055] In this way, determination of the time instants is simplified.

[0056] Preferably, operating said detection device is repeated cyclically over time, more preferably with a period substantially equal to a rotation period of said tyre. In this way, at each rotation of the tyre there corresponds at least one acquisition of the signal, to the advantage of synchronization between acquisition and rotation and of promptness and / or continuous updating of information obtainable from the acquired signal.

[0057] Preferably, provision is made to determine said rotation period of said tyre, for example as a function of said parameter.

[0058] Preferably, determining said parameter representative of the angular velocity is performed based on said previous passage of said detection device in correspondence with said footprint of said tyre.

[0059] Preferably, operating said detection device comprises detecting said previous passage of said detection device in correspondence with said footprint as a function of said signal representative of the motion of the tyre portion acquired during a previous time cycle, more preferably immediately preceding, said current time cycle. In this way, it is possible to determine, in turn, both the parameter representative of the angular velocity and the reference angular position, from which the acquisition time window derives, as a function of the signal in a feedback manner with the last acquisition of the signal performed, to the advantage of increased precision and / or reliability and / or synchronization capability of the acquisition with rotation of the tyre.

[0060] More in detail, determining said parameter representative of the angular velocity is preferably performed as a function of two (directly) previous passages of said detection device in correspondence with said footprint, which are temporally consecutive to each other.

[0061] For example, determining said parameter comprises detecting, for each previous passage, a respective transit of said detection device through a same angular position in correspondence with said footprint and detecting a time elapsed between said respective transits. In this way, from the ratio between the rotation angle and the elapsed time, said parameter is obtained in a simple manner. Moreover, in this way, the rotation period is kept updated with rotation of the tyre.

[0062] Preferably, operating said detection device comprises, in said current time cycle, transmitting, in a transmission time window, said signal representative of the motion of the tyre portion acquired during a time cycle preceding said current time cycle, more preferably immediately preceding, and / or at least one processed data obtained as a function of said signal acquired during said preceding time cycle, more preferably immediately preceding. In this way, the acquired signal data (that is, for example, both the raw signal and / or the at least one processed data) are transmitted promptly. Moreover, in this way, at each time cycle the signal data acquired preferably in the immediately preceding time cycle are transmitted, making available to the processing unit the most recent data, for example for the purpose of determining a new parameter representative of the angular velocity and / or a new reference angular position, and / or determining with high promptness one or more rolling conditions of the tyre from the last acquired in-footprint signal, for example an occurred aquaplaning condition. In this way, sharing of the acquired data with control systems is achieved with the lowest possible temporal granularity, to the advantage of quality of processing data, promptness of computation and reliability of results.

[0063] Typically, said transmitting is performed toward a receiving unit distinct and separate from said detection device. Preferably, said transmission time window is temporally disjoint from said acquisition time window.

[0064] Preferably, said transmission time window is temporally prior to said acquisition time window.

[0065] Preferably, determining said parameter representative of said angular velocity, determining said reference angular position and determining said initial acquisition time instant and said final acquisition time instant are performed in a computation time window.

[0066] Preferably, said computation time window is temporally disjoint from said acquisition time window.

[0067] Preferably, said computation time window is temporally prior to said acquisition time window.

[0068] Preferably, said computation time window is temporally disjoint from said transmission time window.

[0069] Preferably, said computation time window is temporally prior to said transmission time window.

[0070] Preferably, said transmission time window is directly consecutive to said computation time window.

[0071] According to the Applicant, one or more of, more preferably all of, the above-mentioned features relating to temporal arrangement of at least two among the acquisition, computation and transmission time windows allow, in combination with each other, subdivision of the time of a wheel rotation in a highly precise and performant manner in order to perform all desired operations, without temporal overlap, to the advantage of higher precision and lower energy consumption (for example since, by arranging the time windows to be temporally disjoint from each other, it is possible to use less complex processors).

[0072] Preferably, said computation time window is directly consecutive to the acquisition time window of a time cycle (immediately) preceding said current time cycle. In this way, the time cycle restarts immediately after the preceding one.

[0073] Preferably, operating said detection device is performed entirely within said rotation period of said tyre. In this way, the operational cycle of the detection device is consistent with the physical rotation of the tyre, contributing to maintaining the above-mentioned synchronization and / or desired subdivision among the time windows.

[0074] Brief description of the figures

[0075] Figure 1 schematically shows a vehicle provided with a system for operating a detection device according to the present invention;

[0076] Figure 2 schematically shows a detail of Figure 1 ;

[0077] Figure 3 shows a partial section of Figure 2;

[0078] Figure 3b schematically shows a system for operating a detection device according to the present invention;

[0079] Figure 4 conceptually shows a subdivision of a wheel rotation into time phases according to the present invention; Figure 5 shows a logical block diagram of a method according to the present invention;

[0080] Figure 6 shows an example of a signal acquired in the method according to the present invention.

[0081] Detailed description of some embodiments of the invention

[0082] The features and advantages of the present invention will be further clarified by the following detailed description of some embodiments, provided by way of non-limiting example of the present invention, with reference to the accompanying drawings.

[0083] Figure 1 schematically shows a vehicle 99 provided with a system 1 for operating a detection device 4 fixed to an inner surface 5 of a tyre 3 of the vehicle 99, to acquire a signal S representative of a motion of a portion 30 of the tyre 3, according to the present invention. The vehicle 99 may be a vehicle with an internal combustion engine and / or an electric motor, with two or more driving wheels.

[0084] Exemplarily, the vehicle 99 comprises four wheels 7 (distributed on two axles), each provided with a respective tyre 3 (also partially shown in Figure 2) rolling on a surface (not shown). In one embodiment (not shown), the vehicle may have three or more axles.

[0085] The system 1 exemplarily comprises one detection device 4 for each tyre 3 (Figures 1 , 2 and 3). For example, the detection device 4 may be of the type described in one of the following documents in the name of the same Applicant: WO 2018 / 065846 A1 , WO 2019 / 123118 A1 , WO 2020 / 026281 A1 , WO 2020 / 026282 A1.

[0086] Exemplarily, each detection device 4 is fixed on the inner surface 5 of the respective tyre 3, in correspondence with a crown portion of the respective tyre 3 (Figures 2 and 3). In particular, the detection device 4 may be fixed to a liner of the tyre 3, typically by bonding (for example by means of a structural adhesive or by means of a pressuresensitive adhesive - PSA). Preferably, the detection device 4 may be fixed substantially in correspondence with an equatorial plane 200 of the tyre 3. Further detection devices (not shown) may be arranged in a more lateral position on the inner surface of the tyre 3, and / or in different angular positions along the inner circumference of the tyre 3. Exemplarily, the tyre portion 30 therefore coincides with the crown portion arranged in correspondence with the tread band and, substantially, subtended by a base surface of the detection device (that is, the surface by which the device is fixed to the inner surface 5, Figure 3).

[0087] Optionally, the tyre portion 30 may have an extension greater than the base surface of the detection device.

[0088] Exemplarily, each detection device 4 is configured to acquire, typically during rolling of the respective tyre 3, the signal S representative of the motion of the tyre portion. In detail, each detection device 4 exemplarily comprises a respective sensor 41 (schematically shown in Figure 3b) suitable to detect the signal S.

[0089] Exemplarily, each detection device 4 further comprises an electronic unit 40 and an electric energy supply 47, for example a button battery, for supplying electrical power to the electrical and electronic components of the electronic unit and / or of the device 4. The electronic unit comprises, for example, a printed circuit board ("Printed Circuit Board” or "PCB”) on which the electrical and electronic components of the electronic unit are mounted, including the sensor 41 and any further sensors, and on which electrically conductive tracks for electrical interconnection among the various electrical and electronic components of the electronic unit are formed (for example by known abrasion or etching techniques).

[0090] Exemplarily, the electronic unit 40 may comprise, in addition to the sensor 41 , also one or more further sensors, for detecting one or more operating parameters of the tyre and / or further physical quantities. By way of non-limiting example, the operating parameters and / or the further physical quantities detectable may comprise: temperature, tyre deformations, pressure, velocity. Examples of sensors suitable for the above purposes may comprise temperature sensors, pressure sensors, strain gauges, accelerometers, optical sensors, magneto-resistive sensors, inertial sensors, gyroscopes, etc.

[0091] With reference to Figure 3b, by way of example only, the electronic unit 40 may further comprise a processing and transmission system 43 operatively associated with at least the sensor 41 , and typically also with each further sensor, for processing and transmitting one or more data detected by the sensor; for example, the processing and transmission system 43 is configured for transmission to instrumentation available on board the vehicle 99 on which the tyre is mounted. The processing and transmission system may comprise, for example, a microprocessor or an integrated circuit (for example of the ASIC type - "Application Specific Integrated Circuit”) to perform processing and / or analysis of data coming from the sensor 41 , in order to make such data suitable for transmission from the detection device 4 to a receiver external to the tyre, and an antenna to transmit such data and / or receive further data, for example to and from the instrumentation on board the vehicle.

[0092] Exemplarily, the detection device 4 further comprises a casing configured to contain the electronic unit and the electric energy supply. More in detail, the casing comprises a base 45 and a housing body 42 having a plan extension included within the plan extension of the base. Typically, the casing further comprises at least one opening or through-hole in communication with an internal volume of the device in which the electronic unit 40 is housed, in order to allow pressure detection by at least one sensor of the electronic unit 40.

[0093] The system 1 exemplarily further comprises a processing unit 8 (shown only schematically in Figures 1 and 3b by means of a dashed box) operatively connected to the detection device 4, for example by radio signal and / or wired connection, and programmed to operate the detection device 4.

[0094] More in detail, exemplarily, the processing unit 8 is connected to each detection device 4 with which the vehicle is provided, and is programmed to operate each detection device.

[0095] In the example shown, the processing unit 8 exemplarily comprises a remote unit 81 installed on board the vehicle, and (at least) a part (for example the microprocessor or integrated circuit) of the processing and transmission system 43 of each of the detection devices 4 (Figure 3b).

[0096] In general, the present invention contemplates any arrangement and / or logical and / or physical distribution of the processing unit, which may for example be a single physical and / or logical unit or be composed of a plurality of distinct and cooperating physical and / or logical units (as in the case described and shown herein), such units being locatable, wholly or in part, in one or more of the following: the detection device, in particular in one or more of the sensors and / or in the processing and transmission system 43, the tyre (external to the detection device), the rim, on board the vehicle, a remote station in communication with the vehicle.

[0097] In use, the system 1 may perform a method for operating the detection device 4 to acquire the signal S, for example by means of one or more hardware devices programmed by one or more software modules resident and / or loaded on suitable memories.

[0098] An embodiment of the method according to the present invention will now be described with reference to Figures 4-6. The following description refers to a given tyre 3 provided with the respective detection device 4, but may be conceptually extended to each of the tyres 3 of the vehicle 99.

[0099] Exemplarily, operating the detection device 4 is performed cyclically over time with a period substantially equal to a rotation period of the tyre, and entirely within such rotation period. In other words, operating the detection device 4 is therefore, exemplarily performed in consecutive time cycles CY, wherein each time cycle CY corresponds, exemplarily, to a complete rotation (also referred to as a wheel rotation in the context of the present invention) of the tyre about its axis, and is completed within the rotation period of the tyre. Exemplarily, therefore, all operations conceptually included in operating the detection device described below are performed entirely within the respective time cycle CY.

[0100] In the following description, reference will be made to a single time cycle CY of operation of the tyre.

[0101] In general, each time cycle of operation of the detection device exemplarily comprises at least one computation phase of factors (for example at least the parameter representative of the angular velocity and the reference angular position) useful to determine a respective acquisition time window of the signal S for the current time cycle, and at least one acquisition phase of the signal S within such respective acquisition time window, as will now be described in greater detail.

[0102] First of all, given the above-mentioned positioning of the detection device 4 in correspondence with the crown portion, the signal S is exemplarily representative of the motion of such crown portion of the tyre, and coincides with an accelerometric signal representative of at least the radial component of the linear acceleration of the crown portion.

[0103] In one embodiment, the signal S is a velocity signal (or a displacement / deformation signal) representative of at least one component (axial, radial and / or tangential) of a linear velocity (or of a displacement / deformation) of the (crown) portion of the tyre.

[0104] Exemplarily, operating the detection device 4 therefore comprises determining, based on a previous passage of the detection device 4 in correspondence with a footprint 60 of the tyre 3, a parameter w representative of an angular velocity of the tyre 3, xxemplarily coinciding with the angular velocity of the tyre, and determining, based on said previous passage of the detection device 4, also a reference angular position 90belonging to the footprint 60 of the tyre 3.

[0105] More in detail, operating the detection device 4 comprises detecting said previous passage of the detection device 4 in correspondence with the footprint 60 as a function of the signal S representative of the motion of the tyre portion 30 acquired during a time cycle CY immediately preceding the current time cycle CY.

[0106] More in detail, determining the parameter w representative of the angular velocity is performed as a function of two directly preceding passages of the detection device 4 in correspondence with the footprint 60 which are temporally consecutive to each other, each passage being detected as a function of the signal S acquired in the time cycle corresponding to the passage. Exemplarily, determining the parameter comprises detecting, for each previous passage, a respective transit of the detection device through a same angular position in correspondence with the footprint and detecting a time elapsed between the respective transits.

[0107] For example, each of the two above-mentioned passages of the detection device may be detected, for the above purposes, by recognizing within the respective acquired signal S the presence of at least one respective peak. Indeed, particularly when the signal S is representative of the radial component of the linear acceleration of the crown portion, as in the present embodiment, the signal S comprises at least one peak PK within the acquisition time window, as for example shown in Figure 6. Such peak typically corresponds to passage of the device through the footprint and is due to the fact that, during such passage, the radial component of the acceleration undergoes a sudden shift toward values around zero, due to the fact that in the footprint area the curvature of the tyre is substantially null, or, in other words, the radius of curvature of such portion tends toward infinity, causing a substantially abrupt cancellation of the radial acceleration detected by the device (from which the above-mentioned peak originates).

[0108] In this way, thanks for example to peak recognition algorithms, for example based on one or more thresholds, it is possible to determine presence of the peak and therefore recognize passage through the footprint area. Moreover, by taking as a reference a predetermined point of the signal S belonging to the peak, for example the maximum value or a median value, it is possible to detect a temporal coordinate of the peak. Assuming that occurrence of the peak marks passage of the device in correspondence with the footprint, it is therefore possible to derive, from the time elapsed between two directly consecutive passages, the parameter w as well as the rotation period. Moreover, at each subsequent new passage it is possible to update the parameter w by comparing the temporal coordinate of the new passage with the passage directly preceding in time.

[0109] Exemplarily, the reference angular position coincides with an angular position of a geometrical centre of the footprint area 60 of the tyre 3. For example, from the above-mentioned signal S it is possible to determine the spatial extension of the footprint area and therefore the respective geometrical centre.

[0110] Exemplarily, operating the detection device therefore comprises determining an initial acquisition time instant Ti of the signal S as a function of the parameter w representative of the angular velocity and of a predetermined initial angular acquisition position 91 included in a neighbourhood of 90+ 3 / 2TT, and further comprises determining a final acquisition time instant Tf of the signal S as a function of said parameter w representative of the angular velocity and of a predetermined final angular acquisition position Of included in a neighbourhood of 90+ 5 / 2TT.

[0111] For example, said neighbourhoods are preferably symmetric neighbourhoods centred respectively at the values 90+ 3 / 2TT and 90+ 5 / 2TT, having an angular width less than or equal to TT radians, more preferably less than or equal to 2 / 3TT radians. In a particularly preferred embodiment, the initial angular acquisition position coincides with 90+ 3 / 2TT and the final angular acquisition position coincides with 90+ 5 / 2TT.

[0112] Exemplarily, operating the detection device 4 comprises starting, and subsequently stopping, acquisition of the signal S in an acquisition time window TA defined by the initial acquisition time instant Ti and the final acquisition time instant Tf. More in detail, acquisition is exemplarily started at the initial acquisition time instant Ti and stopped at the final acquisition time instant Tf, thus exploiting the entire acquisition time window.

[0113] Exemplarily, therefore, as for example shown in Figure 4, acquisition is performed only during, and for the entire, rotation of the detection device 4 from the initial angular acquisition position to the final angular acquisition position, that is, during movement of the detection device 4 along the trajectory defined by the lower half (which indeed contains passage of the detection device through the footprint area 69) of an entire wheel rotation, said lower half being moreover centred, for each operational time cycle, on the geometrical centre of the footprint portion detected in the preceding time cycle.

[0114] Exemplarily, operating the detection device 4 further comprises determining a further parameter A representative of an angular acceleration of the tyre 3 as a function of the parameter w representative of the angular velocity, more in detail the further parameter A exemplarily coincides with the angular acceleration of the tyre 3.

[0115] Exemplarily, determining the initial acquisition time instant Ti and the final acquisition time instant Tf are further performed as a function also of the further parameter A.

[0116] For example, the further parameter A may be determined as a function of a variation over time of the parameter w. More specifically, in a preferred embodiment, determining the initial acquisition time instant Ti and determining the final acquisition time instant Tf are performed as a function of a time law of a motion imparted to the detection device 4 by rolling of the tyre 3. For example, the time law may be of the following type (approximated to the second- order temporal term and exemplarily describing a uniformly accelerated rotational motion):

[0117] 1,

[0118] 0(t) = 90+ wt + — At2where 90is the above-mentioned reference angular position, w is the parameter representative of the angular velocity, and A is the further parameter representative of the angular acceleration.

[0119] For the time variable t, by imposing 90= 9, the following formula applies for the roots of the above equation: from which Ti and Tf can be obtained by replacing the generic angle 9 respectively with the above-mentioned predetermined initial and final angular acquisition positions 9i and 9f (in the example described herein equal respectively to 3 / 2TT and 5 / 2TT, since 90= 9 has been assumed).

[0120] Exemplarily, operating the detection device 4 further comprises transmitting, in a transmission time window, the signal S representative of the motion of the tyre portion acquired during a time cycle directly preceding, and / or at least one processed data obtained as a function of the signal S acquired during the time cycle directly preceding. In other words, for each time cycle of operation of the tyre, a transmission phase of the data collected in the immediately preceding time cycle is provided.

[0121] Exemplarily, for each time cycle, the transmission time window is temporally disjoint from the acquisition time window and temporally prior to said acquisition time window.

[0122] Exemplarily, for each time cycle, determining the parameter w, the further parameter A, the reference angular position 0O, and each of the initial acquisition time instant Ti and the final acquisition time instant Tf are performed in a computation time window temporally disjoint from the acquisition time window and temporally prior to the acquisition time window.

[0123] Exemplarily, the computation time window is further temporally disjoint from the transmission time window and temporally prior to the transmission time window.

[0124] Exemplarily, the transmission time window is directly consecutive to the computation time window.

[0125] Moreover exemplarily, the computation time window is directly consecutive to the acquisition time window of the time cycle directly preceding.

[0126] In other words, therefore, each time cycle of operation of the detection device exemplarily comprises three distinct time windows arranged in temporal sequence, as for example shown in Figure 4.

[0127] Conceptually, therefore, each time cycle, immediately after completion of acquisition of the preceding time cycle, begins with the computation time window in which the above-mentioned phases are performed. In particular, in the computation time window, the parameter w and the further parameter A, as well as the reference angular position, are determined, which are useful to define the acquisition time window of the current time cycle. In the computation time window, the initial and final acquisition time instants are therefore also determined by way of example.

[0128] In the computation time window, the signal S acquired in the preceding time cycle may further be processed to obtain the above-mentioned at least one processed data.

[0129] Immediately thereafter, the time cycle exemplarily comprises the transmission time window, in which the signal S and / or the above-mentioned at least one processed data are transmitted.

[0130] Subsequently, but not necessarily consecutively, the time cycle comprises the acquisition time window, in which the signal S of the current time cycle is acquired (which will be transmitted and possibly processed in the temporally subsequent time cycle).

[0131] Exemplarily, the time cycle ends at the final acquisition time instant Tf.

[0132] Preferably, moreover (preferably independently of the exemplary embodiment described so far), it is generally provided not to allocate any activity to a portion of the time available of the time cycle CY, preferably the time interval interposed between the end of the transmission time window and the initial acquisition time instant Ti (for example Figures 4 and 6). Such free time interval, or idle time window ID, may be allocated, when needed, to the transmission time window. Indeed, while the acquisition time window has a variable temporal duration depending on the rotation speed of the tyre, since such duration is defined by the (predicted) instants at which the detection device passes through the initial and final angular acquisition positions, and therefore at higher rotation speeds the temporal duration of the acquisition time window is shorter, the transmission time window, by its own nature as time dedicated to data transmission, occurs at a fixed time, that is, it has a fixed temporal duration independently of the rotation speed of the tyre. Therefore, in the case of high speed, presence of the above-mentioned idle time window ID is particularly advantageous to provide additional time to complete transmission of the signal S and / or of the at least one processed data, necessarily before the initial acquisition time instant Ti of the current time cycle.

[0133] The method according to the present invention therefore allows operating the detection device in such a manner as to enable a cyclic acquisition over time of the signal S only within the acquisition time window, but in any case in such a manner as to acquire, for each time cycle, the respective passage of the device in correspondence with the footprint, and therefore with the region of interest, in an autonomously adaptive manner over time also as rolling variables of the tyre vary, such as for example angular velocity and / or angular acceleration.

[0134] Figure 6 shows an example of the signal S acquired by means of the method described in the present embodiment, wherein each acquisition includes passage of the device through the footprint area of the tyre, characterized by the respective peak (in the exemplary case of a radial acceleration signal S). In detail, Figure 6 shows acquisition of the signal S over time t in three consecutive time cycles. It can be observed that, for each time cycle, acquisition is performed only between the respective initial and final acquisition time instants Ti and Tf.

[0135] As mentioned above, what has been described so far relates to operation of the detection device in a temporally cyclic manner with a period equal to the rotation period of the tyre.

[0136] In one embodiment, exemplarily, before operating the detection device in a temporally cyclic manner, the method comprises a preliminary phase of acquiring the signal S in a continuous manner for at least two or three consecutive wheel rotations, that is, for at least two or three complete rotations of the detection device. This allows preliminarily determining at least two consecutive passages of the detection device in correspondence with the footprint (preferably with the footprint area, given positioning of the detection device 4 on the inner surface 5 of the tyre), from which it is possible to determine a first value assumed by the parameter w representative of the angular velocity.

[0137] In such embodiment, the second passage of the device through the footprint of the tyre further allows determining a first value of the reference angular position in order to start cyclic operation of the detection device.

[0138] Preferably, continuous acquisition is maintained for at least one further complete rotation in order to also determine a first value assumed by the further parameter A as a variation of the parameter w between the second and the third wheel rotations.

[0139] At this point, all data useful to establish the first acquisition time window are exemplarily available, and cyclic operation of the detection device can begin.

[0140] In one embodiment, for example alternative to the preceding one, still before operating the detection device in a temporally cyclic manner, for example in order to determine the first values of the above-mentioned parameters, it is possible to perform the preliminary phase of acquiring the signal S in a continuous manner substantially for a single wheel rotation. Indeed, the parameter representative of the angular velocity can be derived from measurement of the radial acceleration, in particular in regions adjacent to the central peak. Such adjacent regions are in fact representative of centripetal acceleration, from which the angular velocity can be derived. From the single wheel rotation it is also possible to derive the corresponding passage of the detection device through the footprint in order to determine the reference angular position and then be able to start cyclic acquisition.

Claims

CLAIMS1. Method for operating a detection device (4) fixed on an inner surface (5) of a tyre (3) to acquire a signal (S) representative of a motion of a portion (30) of the tyre (3), wherein operating said detection device (4) comprises, in a current time cycle (CY):- determining a parameter (w) representative of an angular velocity of said tyre (3);- determining, based on a previous passage of said detection device (4) at a footprint (60) of said tyre (3), a reference angular position 90belonging to said footprint (60) of said tyre (3);- determining an initial acquisition time instant (Ti) of the signal (S) as a function of said parameter (w) representative of the angular velocity and of a predetermined initial angular acquisition position 0i included in a neighbourhood of 0O+ 3 / 2TT;- determining a final acquisition time instant (Tf) of the signal (S) as a function of said parameter (w) representative of the angular velocity and of a predetermined final angular acquisition position 0f included in a neighbourhood of 0O+ 5 / 2TT;- starting, and subsequently stopping, an acquisition of said signal (S) in an acquisition time window (TA) defined by said initial acquisition time instant (Ti) and said final acquisition time instant (Tf).

2. Method according to claim 1 , comprising starting said acquisition at said initial acquisition time instant (Ti) and stopping said acquisition at said final acquisition time instant (Tf).

3. Method according to any one of the previous claims, wherein said initial acquisition angular position coincides with 0-|O + 3 / 2TT and said final acquisition angular position coincides with 0-|O + 5 / 2TT.

4. Method according to any one of the preceding claims, wherein said portion (30) of said tyre coincides with a crown portion of the tyre (3), and wherein said reference angular position O^O coincides with an angular position of a center of a footprint area of said tyre (3).

5. Method according to any one of the previous claims, wherein said signal (S) is an accelerometric signal representative of at least one component of an acceleration experienced by said portion (30) of said tyre (3), and wherein said at least one component of the acceleration is selected from the group: axial component, radial component, and tangential component.

6. Method according to any one of the previous claims, wherein operating said detection device (4) comprises determining a further parameter (A) representative of an angular acceleration of said tyre (3) as a function of said parameter (w) representative of the angular velocity, and wherein determining said initial acquisition time (Ti) and determining said final acquisition time (Tf) are also performed as a function of said further parameter (A).

7. Method according to any one of the previous claims, wherein determining said initial acquisition time (Ti) and determining said final acquisition time (Tf) are performed as a function of an hourly law of a motion imparted to said detection device (4) by a rolling motion of said tyre (3).

8. Method according to any one of the previous claims, wherein determining said parameter (w) representative of the angular velocity is performed based on said previous passage of said detection device (4) in correspondence with said footprint (60) of said tyre (3).

9. Method according to any one of the previous claims, wherein operating said detection device (4) is repeated cyclically over time with a period substantially equal to a rotation period of said tyre (3) and entirely within said rotation period of said tyre (3).

10. Method according to any one of the previous claims, wherein operating said detection device (4) comprises detecting said previous passage of said detection device (4) at said footprint (60) as a function of said signal (S) representative of the motion of the portion (30) of the tyre (3) acquired during a time cycle (CY) immediately preceding said current time cycle (CY).11 . Method according to any one of the previous claims, wherein operating said detection device (4) comprises, in said current time cycle (CY), transmitting, in a transmission time window (TT) temporally disjoint from and prior to said acquisition time window (TA), said signal (S) representative of the motion of the portion (30) of the tyre (3) acquired during a time cycle (CY) immediately preceding said current time cycle (CY) and / or at least one processed data obtained as a function of said signal (S) acquired during said immediately preceding time cycle (CY).

12. Method according to any one of the previous claims, wherein determining said parameter (w) representative of said angular velocity, determining said reference angular position 0-|O and determining said initial acquisition time (Ti) and said final acquisition time (Tf) are performed in a computation time window (TC) temporally disjoint from and prior to said acquisition time window (TA).

13. Method according to claims 11 and 12, wherein said computation time window (TC) is temporally disjoint from and prior to said transmission time window (TT).

14. System (1) for operating a detection device (4) fixed on an inner surface (5) of a tyre (3) to acquire a signal (S) representative of a motion of a portion (30) of the tyre (3), said system (1) comprising said detection device (4) structured to acquire said signal (S) and a processing unit (8), operatively connected to said detection device (4), and programmed to operate in a current time cycle (CY), said detection device (4) performing the following steps:- determining a parameter (w) representative of an angular velocity of said tyre (3);- determining, based on a previous passage of said detection device (4) at a footprint (60) of said tyre (3), a reference angular position 0obelonging to said footprint (60) of said tyre (3);- determining an initial acquisition time instant (Ti) of the signal (S) as a function of said parameter (w) representative of the angular velocity and of a predetermined initial angular acquisition position 0i included in a neighbourhood of 0o+ 3 / 2TT;- determining a final acquisition time instant (Tf) of the signal (S) as a function of said parameter (w) representative of the angular velocity and of a predetermined final angular acquisition position Of included in a neighbourhood of 90+ 5 / 2TT;- starting, and subsequently stopping, an acquisition of said signal (S) in an acquisition time window (TA) defined by said initial acquisition time instant (Ti) and said final acquisition time instant (Tf).

15. System (1) according to claim 14, wherein said detection device (4) is fixed to said inner surface (5) in correspondence of a crown portion of said tyre (3), and wherein said processing unit (8) is programmed to perform said method for operating said detection device (4) according to one or more of claims 2 to 13.

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