Method for estimating vehicle distributed load generated by occupant in vehicle

Abstract

Disclosed is a method for estimating a change in load of a tire wheel assembly on a vehicle caused by boarding of an occupant, the method comprising the steps of: boarding the occupant; recording an internal pressure P in a fluid chamber of the tire wheel assembly equipped with the pressure sensor; determining an internal temperature T in the fluid chamber of the tire wheel assembly equipped with the pressure sensor using the specified variation rule; evaluating the change in volume, [Delta] V, of the tire-wheel assembly equipped with the pressure sensor by means of the determined internal temperature T and the recorded internal pressure P and using a model of adiabatically shifted fluids having a desired gas performance; and estimating the change [delta] Z in the load borne by the n tire wheel assemblies equipped with pressure sensors using a second function including, as parameters, the intermediate change [delta] V in the evaluated volume and the flattening stiffness KP per unit volume of the tires of the tire wheel assemblies.

Description

Technical Field

[0001] This invention relates to the field of determining in real time the changes in load caused by occupants boarding a vehicle, particularly when the vehicle is not moving, enabling the identification of the number of occupants on the vehicle and their location in the vehicle's passenger compartment. Background Technology

[0002] Obtaining the change in static load applied to a stationary vehicle allows for the determination of whether someone is on board. Specifically, determining the change in load applied to an inflation system (such as a tire-wheel assembly) typically requires a balanced weighbridge, which is not easily determined when far from a very specific loading location. To assess the change in load borne by a vehicle outside these specific locations, the load borne by each tire-wheel assembly of the vehicle can be assessed by observing the indentation left by the tires on the ground. While this can be done using systems that quantify static pressure by inserting a measuring system between the tire-wheel assembly and the ground, this is not a straightforward task, and the accuracy of the measurement depends on the correct positioning of the measuring system. An alternative approach is to assess the size of the contact area under driving conditions by measuring the tire deformation as the wheel rotates. By mathematically modeling the tire type, inflation pressure, and the external dimensions of the ground indentation, the change in load applied to the tire can be obtained. Unfortunately, this measurement is performed under driving conditions. Furthermore, achieving accuracy in these measurements becomes exceptionally difficult under very heavy loads. Under such loads, tire deformation, which determines load variations, tends to stabilize in the circumferential direction, and the changes in tire deformation measurements typically fall within this circumferential direction. Therefore, the number of occupants or their positioning within the vehicle cannot be determined before the vehicle is put on the road. In short, it is impossible to verify that each occupant's seatbelt is properly fastened or that the seatbelt restraint force is adapted to the type of occupant, i.e., whether they are an adult or a child.

[0003] The present invention aims to solve the problem of measuring changes in load borne by a vehicle when occupants board without the need for an external measurement system, i.e., it can be used at any time without a specific measuring device. Furthermore, the assessment is performed in a stationary state, allowing the number of occupants and their positions within the vehicle to be announced even before the vehicle begins to move. Summary of the Invention

[0004] This invention relates to a method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, the method comprising the following steps: • In the preparation phase, that is, before at least one passenger has boarded the vehicle, • Each tire wheel assembly of the vehicle is equipped with at least one pressure sensor, which is capable of measuring the internal pressure of the fluid cavity of the tire wheel assembly defined by the tire outer tube and the wheel; • Determine the initial load Z1 applied to at least one tire-wheel assembly equipped with a pressure sensor on the vehicle; • Determine the initial inflation pressure P1 of at least one tire wheel assembly of the vehicle equipped with a pressure sensor; • Determine the initial internal temperature T1 of at least one tire wheel assembly of the vehicle equipped with a pressure sensor; • The initial volume V1 of each tire-wheel assembly equipped with a pressure sensor is evaluated using a first function, the parameters of which include the volume V0 of the fluid cavity of the tire-wheel assembly when unloaded and inflated to an initial pressure P1, and the flattening stiffness K of the tire per unit volume of the tire-wheel assembly. P ; • The number of moles of fluid n in the fluid chamber of each tire wheel assembly equipped with a pressure sensor is evaluated using a model that considers inflation pressure P1, initial volume V1, and temperature T1. • Determine the evolution of the internal temperature T of the fluid cavity based on the internal pressure P during the adiabatic transformation of at least one tire wheel assembly that is inflated, subjected to a load Z1, and equipped with at least one pressure sensor. • During the main phase: • Ensure that at least one occupant is in the vehicle; • Record the internal pressure P of the fluid chamber of each tire wheel assembly equipped with a pressure sensor at a sampling frequency F1; • The internal temperature T of the fluid cavity of each tire wheel assembly equipped with a pressure sensor is determined by utilizing the evolution law determined in the preparatory stage; • Using a determined internal temperature T and recorded internal pressure P, and employing a model of a fluid undergoing an adiabatic transformation, the intermediate volume change ΔV of each tire-wheel assembly equipped with a pressure sensor is evaluated, where the fluid behaves as an ideal gas; and • A second function is used to estimate the load variation ΔZ borne by each tire-wheel assembly equipped with a pressure sensor. The parameters of this second function include the intermediate volume variation ΔV and the flattening stiffness K per unit volume of the tire. P .

[0005] According to a preferred embodiment, in the preparatory stage, each tire wheel assembly equipped with a pressure sensor in the vehicle includes a temperature sensor capable of measuring the temperature of a fluid cavity. The method includes, in the main stage, a step of recording the internal temperature T of the fluid cavity of each tire wheel assembly equipped with a pressure sensor at a sampling frequency F2. The method includes a second step of taking into account the recorded internal temperature T and using a model of a fluid that behaves as an ideal gas and is in thermal equilibrium with the environment outside the fluid cavity to evaluate an intermediate change ΔV2 in the volume of each tire wheel assembly equipped with a pressure sensor.

[0006] The method for determining changes in applied load comprises two consecutive stages. The first stage involves identifying inherent parameters of the tire-wheel assembly before the occupants have boarded the vehicle. This is configured by installing a measurement system onto the vehicle's tire-wheel assembly and identifying initial parameters of the assembly, such as the volume of the fluid chamber, the amount of fluid contained within the enclosed volume defined by the fluid chamber, the load initially applied to the tire-wheel assembly by the vehicle, the internal temperature of the fluid chamber, and the inflation pressure of the fluid chamber in each tire-wheel assembly. Intuitively, when estimating the amount of fluid enclosed in the fluid chamber, it is assumed that the properties of the fluid are known. It is also necessary to have an evolutionary pattern relating the changes in the internal temperature T of the pressure-sensor-equipped tire-wheel assembly to changes in the inflation pressure P when the tire-wheel assembly equipped with the pressure sensor is in operation (specifically, under load Z1, near inflation pressure P1 and temperature T1). This evolutionary pattern can be a default pattern or derived from experimental characterization or numerical simulation of the relevant tire-wheel assembly.

[0007] The second phase represents the step of assessing the change in load applied to each tire-wheel assembly equipped with electronics due to the occupant boarding the vehicle. Electronic devices, including pressure sensors, manage and regulate the recording of pressure measurements. Therefore, when an occupant boards the vehicle, the inflation pressure of the fluid chamber in each tire-wheel assembly equipped with electronics is recorded. In the transient phase, the temporal evolution of physical quantities related to the fluid chamber is important. The occupant's boarding results in a first transformation corresponding to the work generated by this additional load, which can be likened to an adiabatic transformation, i.e., a rapid transformation, and is significant compared to the second transformation. Following the rapid transformation is a slower transformation corresponding to the fluid chamber establishing thermal equilibrium with the external environment through the tire and wheel. This equilibrium is necessary after the change in the internal temperature of the fluid chamber related to the work generated by the occupant boarding. This thermal equilibrium is established slowly due to the thermal inertia of the tire and wheel. Furthermore, the effect of thermal equilibrium on the volume change of the fluid chamber is less than that of the work-related transformation. Therefore, different sampling frequencies can be used for the physical quantities (temperature and pressure). However, it is also possible to use the same sampling frequency for both sensors. Preferably, the electronic device is fixed to the inner wall of the tire. This is because the tire actually deforms the most during adiabatic transformation. If the method uses a temperature sensor, the relative change in temperature measured is greater than the absolute temperature because the temperature sensor is further away from the wheel, since the tire outer layer has lower thermal inertia, and the wheel, especially, being made of metal, inherently has greater inertia than the tire. This improves the accuracy of temperature measurement, thereby enhancing the quality of the method used to measure load changes.

[0008] By utilizing the change in the inflation pressure of the fluid cavity, the change in the internal temperature of the fluid within the cavity can be determined. For these purposes, this change in internal temperature is defined by an evolutionary law previously determined in the preparatory stage. Therefore, this law transforms the measurement of the internal pressure of the fluid in the cavity into an assessment of the internal fluid temperature resulting solely from adiabatic transformation.

[0009] The intermediate volume change of the first volume can then be evaluated using a model of the fluid undergoing an adiabatic transformation. The term adiabatic here means that the transformation experienced by the fluid due to the occupant's entry occurs without external heat exchange between the fluid cavity and the outside of the tire-wheel assembly, assuming this transformation is rapid. Therefore, the first volume change of the fluid cavity caused by the occupant's entry, during an adiabatic transformation, can be estimated solely using the measured change in inflation pressure and the change in internal temperature determined by the evolution of the pressure change within the fluid cavity. It will be assumed, and this is a perfectly reasonable assumption for air or nitrogen, that the gaseous fluid in the fluid cavity of the tire-wheel assembly equipped with a pressure sensor is an ideal gas.

[0010] Preferably, a second fluid transformation is used to evaluate the intermediate change in the second volume. This second transformation relates to the thermal equilibrium between the fluid and the components of the tire-wheel assembly (primarily the tire casing) and the outside. The second volume change experienced by the tire-wheel assembly during this second transformation is then evaluated using the change in internal temperature recorded in the fluid cavity during the transient phase associated with occupant entry, but after the first fluid transformation—that is, when the inflation pressure reaches a steady state. Considering this second volume change ensures better accuracy in evaluating the volume change of the fluid cavity, thereby improving the accuracy of measuring load changes at each tire-wheel assembly equipped with a pressure sensor. However, the intermediate change in the first volume is sufficient to estimate the overload applied to the tire-wheel assembly on the order of first order.

[0011] Of course, considering the temperature change outside the tire-wheel assembly caused by the thermal balance of the tire-wheel assembly also allows for more detailed measurement of the second volume change caused by occupant boarding at each tire-wheel assembly equipped with a pressure sensor. However, in a simpler approach, since the tire-wheel assembly is preferably in a thermomechanically stable state, the initial internal temperature T1 of the fluid in the fluid cavity of the tire-wheel assembly can be considered from the external temperature.

[0012] These two transformations can occur at each time increment, or one after another over a period of measurement. These assessments of intermediate volumetric changes require measurements of the time it takes for the vehicle's load to reach mechanical and, possibly, thermal equilibrium at the tire-wheel assembly. Once these forms of equilibrium are established, the temperature and pressure changes in the fluid cavity are very small, leading to a further thermomechanical steady state.

[0013] Once the intermediate volume variation of each tire-wheel assembly equipped with a pressure sensor has been assessed, it is necessary to evaluate the relevant changes in static load caused by occupant entry into each tire-wheel assembly of the vehicle equipped with a pressure sensor. This requires converting the intermediate volume variation of each tire-wheel assembly into an equivalent load variation. For this purpose, it is appropriate to consider the characteristics of the tire-wheel assembly (especially the tire), referred to as the flattened stiffness K per unit volume. PThis quantity provides the correlation between the load borne by the tire-wheel assembly and the change in volume of the fluid cavity caused by the load, which is flattened on a ground perpendicular to the applied load. This characteristic can, of course, be a default quantity, or it can be obtained through experimental characterization of the tire-wheel assembly, or derived through numerical simulation activities of the same tire-wheel assembly. The tire-wheel assembly needs to be under operating conditions close to those observed in the preparatory phase (i.e., near the internal temperature T1 and inflation pressure P1). Typically, this flattening stiffness of the tire-wheel assembly is a quantity locally defined near the initial operating point of the tire-wheel assembly in a reference frame related to the internal pressure P, internal temperature T, and volume V of the fluid cavity.

[0014] Preferably, prior to the main steps, at least one tire-wheel assembly equipped with a pressure sensor is in a thermomechanically stable state.

[0015] Preferably, the transient phenomena recorded at the sensors of the electronic device are attributed solely to disturbances to the vehicle's balance caused by the occupant's entry. Therefore, other disturbances do not affect the sensor response, and this improves the accuracy of load variations assessed using this method. However, the method remains perfectly relevant if the disturbance to the vehicle's balance occurs on a different timescale than the disturbance related to the occupant's entry, or if the disturbance is expressed in a small magnitude in the sensor response of the electronic device.

[0016] Advantageously, the pressure sensor and / or temperature sensor are disposed in a subspace of a closed fluid cavity defined by the tire outer tube and the wheel.

[0017] Advantageously, sensors measuring low-amplitude transient phenomena are positioned close to the location where these transient phenomena occur, so that the response is not drowned out by measurement noise. Therefore, for example, when a centralized inflation pressure system for the tire-wheel assembly is present, it is advantageous to place the sensor at the tire-wheel assembly rather than at the centralized system. Similarly, measurements will be more accurate if the sensor is positioned on the tire surface inside the tire than if the sensor is mounted on the rim, because the measurement location is farther from the location where the physical phenomenon occurs, which, due to its transient nature, affects the deformation of the tire outer layer. Finally, preferably, sensors, especially temperature sensors, are positioned such that they are far from the wheel, which has a higher thermal inertia than the tire.

[0018] Advantageously, the pressure sensor operates with a resolution of less than 1 millibar.

[0019] Therefore, smaller changes in volume can be evaluated, and thus smaller changes in load can be evaluated.

[0020] Preferably, the sampling frequency F1 is between 0.1 Hz and 10 Hz.

[0021] Optionally, the sampling frequency F2 is lower than the sampling frequency F1.

[0022] A higher acquisition frequency F1 is beneficial in order to capture the rapid first transformation of the fluid. Since frequency F2 is correlated with the recording from the second sensor, such a high frequency is unnecessary because the second transformation of the fluid is inherently slower. However, it is entirely possible to use the same acquisition frequency for both sensors when using frequency F1 as a reference.

[0023] According to a particular implementation, the determination of the initial volume V0 takes into account the geometry of the rim and the geometry of the unloaded tire mounted on the rim and inflated to a reference pressure P0, preferably, the reference pressure P0 is the initial pressure P1.

[0024] Advantageously, the geometry of the tire and / or the wheel is determined using the tire and / or wheel identifiers of the tire and / or wheel assembly equipped with pressure sensors. Preferably, the tire and / or wheel identifiers are obtained by radio frequency interrogation of electronics located on the tire and wheel assembly.

[0025] In order to initialize the measurement system and, in particular, determine the initial volume V1 of the fluid cavity, it is appropriate to determine the volume V0 of the fluid cavity, which corresponds to the volume defined by the unloaded tire wheel assembly (i.e., the tire mounted on the rim) at a reference inflation pressure P0, preferably the initial pressure P1.

[0026] To determine the volume V0, the axisymmetric geometry of the unloaded tire at a reference inflation pressure P0 is required. In reality, it is assumed that the rim geometry is unaffected by the tire-wheel assembly inflation pressure. These geometries can be accessed via a tire database. Knowing the tire and / or rim identification allows the correct geometry to be identified from this database. Tire identification can be obtained by optically reading regulatory markings affixed to the tire sidewall. Identification can also be transmitted via radio frequency interrogation of electronic devices present on the tire-wheel assembly, such as Radio Frequency Identification (RFID) tags, tire-mounted sensors (TMS) mounted on the tire liner, or tire pressure monitoring systems (TPMS) mounted on the rim.

[0027] Preferably, the load Z on each tire-wheel assembly equipped with a pressure sensor is estimated using the first relationship of the following formula: [Mathematical Expression 1] , Among them, K PP It is the aerodynamic flattening stiffness per unit volume of the tire in the tire-wheel assembly.

[0028] This is a simple and basic model that correlates the load applied to the tire with the volume change of the fluid cavity of the tire-wheel assembly between a first state of volume V0 (e.g., unloaded) and a second state of volume V1, the inflation pressure P of the fluid cavity, and the aerodynamic stiffness of the tire-wheel assembly corresponding to its flattening in a plane. This model assumes that the structural stiffness of the tire-wheel assembly is negligible compared to its aerodynamic stiffness, an assumption that is realistic for the tire outer casing of a particular vehicle. However, the structural stiffness of the tire can be fully accounted for in the preceding formulas by multiplying the tire's structural stiffness by the product of its aerodynamic stiffness and the inflation pressure.

[0029] According to a favorable implementation, the volume change ΔV of each tire-wheel assembly equipped with a pressure sensor is estimated by solving the following differential equation: [Mathematical Expression 2] ,and [Mathematical Expression 3] , Where P is the internal pressure of the fluid cavity, V is the internal volume of the fluid cavity, and T is the internal temperature of the fluid cavity.

[0030] This differential equation represents the relationship between parameters of the fluid in the fluid cavity of the tire wheel assembly, which are first controlled by the adiabatic transformation of the fluid and secondly by the fact that the fluid is an ideal gas.

[0031] The present invention also relates to a method for estimating the number and location of occupants in a vehicle, the method comprising estimating the change in load on the tire and wheel assembly of the vehicle caused by at least one occupant boarding a stationary vehicle, wherein the vehicle's track width V and wheelbase E, as well as the average load point of the occupant in each seat of the vehicle, are determined, the method comprising the following steps: • The total load P generated by at least one occupant is determined by summing the load variation ΔZ borne by each tire wheel assembly equipped with a pressure sensor in the vehicle; • Determine the center of gravity G of the total load P generated by at least one occupant, and obtain the coordinates of the center of gravity G in the vehicle-related reference frame R; • The average number of occupants N is determined as the ratio between the total load Z generated by at least one occupant and a reference value REF, wherein the reference value REF preferably represents the average weight of an adult; • Identify the combination of positioning and occupant type on each seat of a vehicle that matches the average number of occupants N; • For each identified combination of occupants, determine the coordinates of the center of gravity J of all occupants in reference frame R; and • Identify the best possible combination that minimizes the distance between the centroid G and the centroid J.

[0032] Advantageously, passenger types are included in groups containing adult males, adult females, adolescents, and children.

[0033] The method used to estimate the number of occupants in a vehicle and their positions within the vehicle is based on estimating the variation in load across all loaded tire and wheel assemblies of the vehicle. The estimated load variation is caused by the occupants' expected positions in the vehicle (e.g., seats or multiple rows of seats) upon boarding.

[0034] The estimated load changes are summed to obtain the total load on the vehicle occupants. This corresponds to the first step. Furthermore, since the vehicle's track width V and wheelbase E are known, the center of gravity G of this total occupant load can be easily determined. This center of gravity G corresponds to the center of mass of the wheel centers of the tire-wheel assemblies equipped with pressure sensors, each wheel center being weighted by the load changes observed on the corresponding tire-wheel assemblies equipped with pressure sensors.

[0035] Next, the total load P is divided by a reference value REF to obtain the quantity, which is analogous to the mass of a specific occupant type. Preferably, this is an adult occupant of any gender. The quantity obtained by this division is close to an integer or an odd multiple of 0.5. Then, odd multiples of 0.5 correspond to the mass of a child, which is equivalent to half the mass of an adult.

[0036] Based on the obtained quantity, various combinations of the number of different types of occupants can be identified. Since the number of occupants in passenger vehicles is relatively small, there are only a few possible combinations. For example, the quantity 2.4 is rounded up to 2.5. This value 2.5 corresponds to several combinations of the possible number of various types of occupants in the adult and child groups. Therefore, in the case where the average weight of a child is half that of an adult, it could be one adult and three children, or two adults and one child. For such combinations of possible occupant numbers, it is necessary to multiply them by the various possibilities of the occupants' positions in the various seats and bench seats of the vehicle. This yields all possible combinations of occupants and their positions in the vehicle.

[0037] Next, for each identified possible combination i, the center of gravity Ji is evaluated, which corresponds to the center of mass of the average bearing point of the occupant in each seat of the vehicle, each point being weighted by the mass of the occupant present in the relevant seat. Where possible, the location of each center of gravity Ji for each combination i is represented in the same vehicle reference frame as the location of the center of gravity G representing the load variation.

[0038] Finally, the optimal possible combination i is identified, which minimizes the distance between the center of gravity G, which relates to the change in load borne by the tire-wheel assembly, and the center of gravity Ji, which relates to the number of occupants and their positioning in the vehicle. Choosing the center of gravity as the measurement allows the identification to focus on a few parameters, thus benefiting the identification in terms of resource and time costs. Furthermore, in cases involving the measurement of changes in load on the tire-wheel assembly, this will be reflected in the deviation between the center of gravity G and the possible point Ji.

[0039] The present invention also relates to a method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle and / or a system for estimating the number and location of occupants of a vehicle, the system comprising: • A vehicle capable of accommodating at least one occupant in a seat, wherein each tire wheel assembly of the vehicle is equipped with electronic devices; • An electronic device comprising at least one pressure sensor, at least one electronic chip, at least one storage space capable of recording signals from the sensor, and at least one first radio frequency communication device capable of transmitting, the electronic device preferably being fixed to the inner wall of the tire, more preferably being fixed to the tread of the tire. • At least one computing device; and • At least one display device, which includes at least one second radio frequency communication device capable of receiving signals.

[0040] As described in this method, it is suitable that the pressure sensor is located at the tire-wheel assembly, which has rotational motion relative to the vehicle. To distance the electronics from those components of the tire-wheel assembly with the greatest thermal inertia, the electronics are fixed to the inner wall of the tire at the tire crown, especially if the device includes a temperature sensor. Therefore, for the electronics that at least regulate the signal from the pressure sensor, it is suitable that the electronics are provided with a transmission (e.g., radio frequency) communication device to easily send data to outside the tire-wheel assembly where at least the display device is located. Specifically, an alternative is to integrate a computing device that calculates the volume change of the inner cavity of the tire-wheel assembly into the tire-wheel assembly. This computing device can be integrated into the electronics or communicate with the electronics via a wired connection. The radio frequency communication device of the electronics then facilitates the transmission of the calculation results outside the tire-wheel assembly. The radio frequency communication from the electronics of the tire-wheel assembly can be directed to the vehicle or to a vehicle-external device such as a mobile phone, tablet, or computer. These three elements can then represent the display device. However, the display device can also be a graphical interface of the vehicle, such as on a dashboard.

[0041] Therefore, the proposed structural form can be adapted to many possible technical configurations while having the functionality to implement the method.

[0042] Preferably, the system includes an analysis device capable of analyzing results output by at least one computing device.

[0043] The results from the computing device are not only the changes in load borne by each tire wheel assembly equipped with electronic devices, but also some intermediate objects used in the process of identifying the optimal combination, enabling the identification of the number of occupants and their positions within the vehicle. The analytical element enables decision-making, and particularly the identification of the best possible combination. This optional element of the system capable of serving the vehicle's users needs to be located between the computing device and the display device. Structurally, it can be associated with one and / or the other via a wired connection, or physically separated from these elements via radio frequency communication devices.

[0044] According to a first specific embodiment, at least one computing device includes at least one third radio frequency communication device capable of transmitting / receiving.

[0045] In situations where the computing device is physically separated from the electronic and display devices, the computing device needs to be able to communicate with the other two components. This is true, for example, when the computing device is in a vehicle: the computing device collects pressure data from the electronic device via radio frequency communication. Conversely, if the display device is in a mobile phone, the computing device sends calculation results to the display device via the same radio frequency communication.

[0046] According to a second specific embodiment, at least one analysis device includes at least one fourth radio frequency communication device capable of transmitting / receiving.

[0047] In cases where the analysis device is physically separated from both the computing device and the display device, the analysis device needs to be able to communicate with the other two components. This is true, for example, when the analysis device is located on a server located away from the vehicle: the analysis device collects information from the computing device located on the vehicle regarding changes in loads applied to the various tire and wheel assemblies of the vehicle via radio frequency communication. On the other hand, if the display device is on a mobile phone or any other electronic device with a screen, the analysis device sends a message generated based on a comparison between the center of gravity G and the center of gravity Ji by sending the number and location of the occupants to the display device via radio frequency communication.

[0048] According to a third specific embodiment, the system includes at least one reading device capable of reading data contained in at least one storage space of an electronic device, the at least one reading device including at least one fifth radio frequency communication device capable of transmitting / receiving.

[0049] When the communication range of an electronic device is insufficient to provide communication for a display device, it is appropriate to utilize a reading device to collect data from the electronic device. This reading device performs the function of capturing measurement data. It then transmits this data via radio frequency communication to the display device or any other element of the system that requires the data, thus preparing for the remainder of the method. It acts as an information repeater, thereby optimizing communication coverage relative to the electronic device present in the tire-wheel assembly. Specifically, to reduce the mass of the electronic device at the tire, it is appropriate to limit the energy source required for data transmission, which is the energy-consuming function of the electronic device.

[0050] Preferably, a portion of the communication performed by the communication device between itself and an element included in the group comprising an electronic device, at least one computing device, at least one display device, at least one analysis device, and at least one reading device is performed using UHF radio waves, and preferably using Bluetooth Low Energy (BLE).

[0051] The Ultra High Frequency (UHF) band is capable of transmitting data at advantageous bit rates, particularly at higher frequencies within the UHF band (such as the BLE band). It is commonly used in transportation applications, meaning that the system's communication methods can be shared with existing communication methods on vehicles or in roadside infrastructure.

[0052] Advantageously, at least one display device is included in the group comprising a telephone, a computer, and a human-machine interface located on the vehicle, preferably on the vehicle dashboard.

[0053] The display device is used to alert individuals operating in the vehicle to the safety status of their semi-trailer truck, whether that individual is the driver in the cab or another person responsible for the compliance of the semi-trailer truck.

[0054] According to one advantageous embodiment, at least a portion of the reading device is located on the vehicle.

[0055] According to another advantageous embodiment, at least a portion of a computing device and / or at least a portion of an analysis device is located on the vehicle, preferably on the tire-wheel assembly.

[0056] Since the tire and wheel assembly is connected to the vehicle and the process output is destined for the vehicle or its user, the vehicle acts as a natural information relay. Therefore, while it is entirely desirable for the system's structural components to be located on the vehicle, alternatives remain possible. However, unlike communication with a server, the vehicle provides a degree of data confidentiality unless secure communication protocols are in place. Of course, to minimize the system's impact on today's complex and heavily loaded vehicle environment, positioning the functionality on the tire and wheel assembly limits interference with other structural components of the vehicle. Attached Figure Description

[0057] The invention will be better understood by reading the following description, given only by way of non-limiting example and with reference to the accompanying drawings, wherein the same reference numerals always denote the same parts, and in the drawings: • Figure 1 A method for estimating the change in load on the tire and wheel assembly of a vehicle caused by occupants boarding the vehicle, according to a first embodiment of the present invention, is shown. • Figure 2 Another configuration of the system according to a second embodiment of the present invention is shown; • Figure 3 A block diagram is shown of a method according to the invention for estimating the change in load borne by the tire-wheel assembly of a vehicle, the change being caused by occupants boarding the vehicle, and / or a method for estimating the number of occupants and their positions in the vehicle. • Figure 4 The time evolution of the internal pressure of the fluid cavity, output by a pressure sensor, is shown; • Figure 5 The time evolution of the internal temperature of the fluid cavity is shown; • Figure 6 An estimate of the volume change of a fluid cavity relative to time according to the present invention is shown; • Figure 7 An estimate of the load on the vehicle's tire and wheel assembly as a function of time is shown, which is related to the occupants boarding the vehicle. Detailed Implementation

[0058] Figure 1 An example of system 2000 is shown, which implements a method for estimating the change in load on the tire wheel assembly of a vehicle caused by occupants boarding. System 2000 includes a vehicle 2001, which includes four tire wheel assemblies 2006 distributed on two axles of the vehicle, the front axle and the rear axle, in the direction of forward travel of vehicle 2001. Here, the vehicle includes three occupants, only two of whom are shown in the figure. Two adults sit in the front seat, while a child sits in the rear seat directly behind the driver's seat. Therefore, the three occupants exert a force P generated by their respective masses at the occupant's point of contact in vehicle 2001. This force P is applied at the center of gravity G. The presence of the external force P at point G of the vehicle (which corresponds to the center of gravity of the occupants' masses in vehicle 2001) results in additional reaction forces ΔZ1 and ΔZ2 being applied to the tire wheel assembly 2006 of each corresponding axle. These additional reaction forces stabilize when a steady state is reached to balance force P.

[0059] The purpose of this method is to determine the reaction forces on each tire wheel assembly of a vehicle that becomes stable when it reaches a steady state.

[0060] Each tire wheel assembly 2006 of vehicle 2001 is equipped with an electronic device 2007. This electronic device 2007 is located within a fluid chamber of the tire wheel assembly 2006. Here, the electronic device 2007 is disposed on the inner wall of the tire, aligned with the tread of the outer tire, which provides contact between the outer tire and the ground. The electronic device can be mounted on the rim of the tire wheel assembly while remaining within the fluid chamber of the tire wheel assembly 2006. For example, the electronic device can be integrated into the rim valve, similar to some tire pressure monitoring systems (TPMS).

[0061] The electronic device 2007 includes a pressure sensor associated with a microcontroller and at least a radio frequency (RF) device capable of transmission. Therefore, the RF device includes a radio wave generator and a radio communication antenna for transmitting the generated radio waves. The RF device may also optionally include a radio wave receiver for receiving instructions from the outside to, for example, initiate a measurement. The electronic device 2007 also includes storage space for storing measurement data from the pressure sensor before transmitting it in the form of radio waves. The electronic device can transmit raw measurement data or data filtered by the microcontroller. Of course, the pressure sensor is often accompanied by a temperature sensor. In this case, the electronic device 2007 transmits both pressure and temperature data to the outside of the tire wheel assembly 2006. Here, the electronic device 2007 transmits radio waves in the Ultra High Frequency (UHF) band, and more specifically in the Bluetooth Low Energy (BLE) band.

[0062] Here, the external component includes at least vehicle 2001. Vehicle 2001 first includes a radio data reader 2005, which operates in the UHF band, and its antenna is located near the tire-wheel assembly 2006 to collect measurement data generated by electronic device 2007. The data is then transmitted via a wired connection to a computing device 2002 located within vehicle 2001. Radio frequency transmission using a specific communication device is also possible. The computing device 2002 includes storage space and a processor for performing the following tasks: identifying quantities from the tire-wheel assembly corresponding to an initial state; solving differential equations to determine the volume change of the fluid cavity in each tire-wheel assembly equipped with electronic device 2007; and calculating the load change associated with the volume change, the volume change having previously collected the tire quantity required for this task. Next, the tasks related to estimating the optimal possible combination of occupants and their positions involve: summing the load variations borne by each tire wheel assembly 2006 of vehicle 2001 and locating the centroid G of the wheel center of the tire wheel assembly 2006, each wheel center being weighted by the various load variations borne; estimating the total number of occupants by dividing the total load borne by a reference value REF; identifying all possible combinations of occupants and their positions within the vehicle; and for each possible combination, evaluating the centroid Ji of the seated occupant's position, weighted by the mass of each occupant. Finally, the last step involves identifying the optimal possible combination, which minimizes the distance between point G and point Ji.

[0063] The results, and more specifically, the final data items, are sent to the analysis device 2004. Here, this data is transmitted via wired connection, but radio frequency communication may have been established. Of course, the analysis device 2004 can be integrated into the computing device 2002.

[0064] Finally, various output data from the analysis device 2004 are transmitted to the display device 2003 via the fourth communication device 2104 and the second communication device 2102 present on the display device 2003. In particular, the fourth communication device 2104 is implemented by the radio communication antenna of the vehicle 2001.

[0065] These communication devices 2104 and 2102 transmit their data to a tablet or smartphone 2003 via a communication network in order to signal whether the vehicle's load meets or does not meet the thresholds permitted for use in vehicle 2001 under current regulations.

[0066] The results obtained can determine the dimensions of certain safety components of the vehicle or allow for additional verification, such as ensuring that occupants are properly configured in the vehicle before it is started.

[0067] Figure 2 Another configuration of system 2000 is shown. System 2000 includes vehicle 2001, which includes a four-wheel assembly 2006 distributed on two axles of the vehicle, which are the front axle and the rear axle in the direction in which vehicle 2001 travels forward. The vehicle includes a single occupant who will drive vehicle 2001.

[0068] Each tire wheel assembly 2006 of vehicle 2001 is equipped with an electronic device 2007. This electronic device 2007 is located within a fluid chamber of the tire wheel assembly 2006. Here, the electronic device 2007 is disposed on the inner wall of the tire, aligned with the tread of the outer tire, which provides contact between the outer tire and the ground. The electronic device can be mounted on the rim of the tire wheel assembly while remaining within the fluid chamber of the tire wheel assembly 2006. For example, the electronic device can be integrated into the rim valve, similar to some tire pressure monitoring systems (TPMS).

[0069] The electronic device 2007 includes a pressure sensor associated with a microcontroller and at least a radio frequency (RF) device capable of transmission. Therefore, the RF device includes a radio wave generator and a radio communication antenna for transmitting the generated radio waves. The RF device may also optionally include a radio wave receiver for receiving instructions from the outside to, for example, initiate a measurement. The electronic device 2007 also includes storage space for storing measurement data from the pressure sensor before transmitting it in the form of radio waves. The electronic device can transmit raw measurement data or data filtered by the microcontroller. Of course, the pressure sensor is often accompanied by a temperature sensor. In this case, the electronic device 2007 transmits both pressure and temperature data to the outside of the tire wheel assembly 2006. Here, the electronic device 2007 transmits radio waves in the ultra-high frequency (UHF) band, and more specifically in the Bluetooth Low Energy (BLE) band.

[0070] Here, the external component includes at least vehicle 2001. Vehicle 2001 primarily includes a radio data reader 2005, which operates in the UHF band, and its receiving antenna 2105 is located near the tire-wheel assembly 2006 to collect measurement data generated by electronic device 2007. The data is then transmitted via a wired connection to the transmitting antenna of a communication device 2105 associated with the data reader 2005 located in vehicle 2001. Radio frequency transmission using a specific communication device is also possible between the transmitting communication device 2105 and the data reader 2005.

[0071] The data is then sent to a physical device located away from vehicle 2001.

[0072] The first device is a computing device 2002, which includes transmitting / receiving communication devices 2102. These communication devices 2102 receive radio waves transmitted by transmitting communication devices 2105 to convert them into digital data usable by the computing device 2002. The computing device 2002 includes storage space and a processor for performing its tasks: identifying quantities from the tire-wheel assembly corresponding to an initial state, solving differential equations to determine the volume change of the fluid cavity in each tire-wheel assembly equipped with electronics 2007, and finally calculating the load change associated with the volume change, which has previously been used to collect the tire quantity required for this subsequent task.

[0073] The results, and more specifically, the final data items, are sent to a second device corresponding to the analysis device 2004. Here, this data is transmitted via radio frequency communication. The analysis device 2004 operates based on the results of the computing device 2002 and vehicle characteristics (e.g., the wheelbase V and track width E between the vehicle's tire and wheel assemblies 2006), the results of which are collected by the analysis device 2004 through radio frequency transmission from the computing device 2002 using the receiving communication device 2104. These values ​​may be transmitted by querying a remote database containing data related to the vehicle 2001. Alternatively, according to another embodiment, the analysis device 2004 may be integrated into the computing device 2002.

[0074] Finally, various output data from the analysis device 2004 are transmitted to the display device 2003 via a fourth communication device 2104 and a second communication device 2102 located on the display device 2003. Here, there are two display devices. First, a digital tablet computer 2003, possibly located remotely from the vehicle 2001, and a human-machine interface 2003 within the vehicle 2001, which includes a display screen on the vehicle 2001's instrument panel.

[0075] The purpose of the display device 2003 is to signal to the driver or any control device of the vehicle 2001 the number of occupants on the vehicle and their location in the vehicle 2001.

[0076] Of course, these two embodiments of the system for implementing a method for estimating the changes in load on the vehicle's tire and wheel assembly caused by occupants boarding are merely illustrative examples of the system and are not limited to these two configurations. The first extreme configuration involves integrating all computing and analysis devices into an electronic device mounted on the tire and wheel assembly and sending the results to a display device remote from the vehicle. The other extreme configuration involves transmitting measurement data recorded at the electronic device via radio waves and performing other steps of the method on a device remote from the vehicle, without needing to pass through the vehicle.

[0077] Figure 3 A block diagram is shown of a method for estimating the change in load on the tire and wheel assembly of a vehicle caused by an occupant boarding a stationary vehicle. The method comprises several stages.

[0078] The first stage is a preparatory stage, which includes at least actions 1 to 6, performed sequentially by a connecting system depicted as a continuous line. This preparatory stage focuses on the vehicle before the occupants have boarded and obviously includes equipping the vehicle with pressure sensors (ideally at the tire-wheel assembly) capable of measuring the pressure of the fluid cavity defined by the inner surface of the tire and the rim using dedicated electronic devices. The first steps, indicated as 1 and 2, involve determining physical quantities related to the fluid cavity of the tire-wheel assembly equipped with the measuring device, such as inflation pressure P1 and internal temperature T1. Preferably, these determinations can be made as default values ​​or by capturing specific measurements. The step indicated as 3 involves determining the load Z1 borne by the tire-wheel assembly equipped with the vehicle's measuring device. This determination can be made by assuming the total load of the vehicle is distributed among the various axles of the vehicle as a default value. The total load of the vehicle is, for example, a data item from the manufacturer and corresponds to, for example, the unloaded mass of the vehicle specified in the vehicle manufacturer's technical data sheet. Of course, it may also include a fuel tank filled with fuel and luggage in the vehicle's trunk. Step 4 in the attached figure corresponds to obtaining specific quantities from the tire-wheel assembly equipped with measuring devices. One of these quantities is volume V0, which corresponds to the volume occupied by the fluid cavity of the tire-wheel assembly when it is inflated to pressure P1, strictly speaking, at internal temperature T1, but without any load (i.e., not even placed on the ground). The second quantity is the flattening stiffness Kp per unit volume of the tire outer tube of the tire-wheel assembly, which may depend on the inflation pressure P1, internal temperature T1, and the load Z1. Finally, the third set of quantities is related to the laws governing the behavior of ideal gases, which apply to the properties of the gas contained in the fluid cavity of the tire-wheel assembly. Additionally, the penultimate step of the preparatory stage (attached to figure 5) is the step of determining the volume V1 occupied by the fluid cavity of the instrumented tire-wheel assembly under load Z1 and at inflation pressure P1 and temperature T1. Finally, the last step in the preparatory stage (denoted as 6) is to assess the amount of gas contained in the fluid cavity of the instrumented tire-wheel assembly by determining the number of moles n of gas present in volume V1. Here, although the assumptions associated with ideal gas conditions do apply, it is still necessary to determine the compositional properties of the gas, i.e., whether it is a single type of gas or a mixture of gases. Additionally, in this preparatory stage, even though not shown, it is important to determine the evolution of the relationship between the change in internal pressure P and the change in internal temperature T of the fluid in the fluid cavity of the relevant tire-wheel assembly during the adiabatic transformation near the operating point of the tire-wheel assembly (i.e., pressure P1, temperature T1, and load Z1).

[0079] The method then proceeds to the main steps, which begin corresponding to occupant boarding. As needed, the time-varying pressure change P(t) of each instrumented tire wheel assembly of the vehicle is recorded; in the case of a passenger vehicle, this change is on the order of 1 millibar. These records are then stored in storage, allowing the raw data to be filtered using a low-pass filter to eliminate high-frequency phenomena; this corresponds to step 11 in the figure. Next, the time-varying temperature change T(t) of the internal fluid cavity is determined using the evolution law determined in the preliminary steps, based on the time-varying internal pressure P(t); this corresponds to step 12. Optionally, if the vehicle is equipped with temperature sensors, the time-varying temperature change T(t) of the internal temperature of each instrumented tire wheel assembly of the vehicle is recorded; this also corresponds to step 12. In this option, the recorded internal temperature change T(t) is used to assess the isobaric or monobaric transformation of the fluid in the fluid cavity, which corresponds to establishing thermal equilibrium between the fluid cavity and the external environment, necessary due to the adiabatic transformation of the fluid associated with occupant boarding. The connection system between the optional steps and the steps essential to the method is illustrated using lines shown in gray instead of black. However, the connecting lines belonging to the main stages are shown as dotted lines, while those belonging to the preparatory stages are shown as solid lines. Finally, as will be seen below, the secondary stages have a connecting system depicted in dashed (dotted-dashed) form.

[0080] A key step in the main phase is determining the volume change ΔV of the fluid cavity in each instrumented tire-wheel assembly via step 13. This corresponds to at least considering the adiabatic transformation of the fluid in the fluid cavity due to the occupant's entry into the vehicle, which alters the thermomechanical balance of all tire-wheel assemblies and thus the thermomechanical balance of the fluid enclosed in each fluid cavity of the tire-wheel assembly. Furthermore, it is assumed that the fluid behaves as an ideal gas. Based on the change in internal pressure P(t) of each instrumented tire-wheel assembly, the change in internal temperature T(t) can be determined using the evolutionary pattern established during the preparatory phase of the adiabatic transformation of the fluid.

[0081] By utilizing changes in internal pressure and internal temperature, a differential equation considering the aforementioned assumptions can be input. Solving the differential equation in time increments allows estimation of the relevant time change ΔV(t) in the fluid cavity volume. Optionally, this method can be supplemented by measuring the internal temperature T of the fluid cavity to assess a second volume change in the fluid cavity, which is related to the isobaric or monobaric transformation of the fluid resulting from heat exchange between the fluid cavity of the tire-wheel assembly and the external environment via the components of the tire-wheel assembly (i.e., the tire and wheel). This second transformation typically follows an adiabatic transformation, as the temperature change resulting from the adiabatic transformation is the root cause of the lack of thermal equilibrium between the fluid cavity and the external environment.

[0082] Another important step in the main phase is to evaluate the change in load ΔZ, which is only related to the previously evaluated change in volume ΔV, corresponding to step 14. For this, the flattened stiffness K per unit volume of the tire-wheel assembly needs to be considered again. P This stiffness can include both aerodynamic and structural components. Considering only the aerodynamic component K... PP This may be sufficient to provide a reliable estimate of the load variation ΔZ.

[0083] For the method used to estimate the number of occupants and their location within the vehicle, in step 21, the variation ΔZ of the load borne by each tire-wheel assembly needs to be summed to obtain the occupant weight P and the center of mass G of the wheel center of each tire-wheel assembly, each wheel center being weighted by the variation of the load on the tire-wheel assembly. For this purpose, the vehicle's track width V and wheelbase E need to be determined, corresponding to step 20. Thus, the wheel centers can be positioned relative to each other in a vehicle-related reference frame. In step 22, the quantity N is calculated based on the weight P of all occupants by dividing the weight P by a reference value REF. This value REF relates to the mass of the occupant type (e.g., adult).

[0084] Next, based on the identified quantity N, the possible number of occupants is determined according to various occupant types. The difference between different occupant types lies in their mass. Therefore, it is easy to identify at least adult occupants and child occupants. The mass of a child occupant is then approximately half the mass of an adult occupant. Therefore, in this particular case, the quantity N is close to an integer or a multiple of 0.5, allowing for the identification of various combinations of occupant types. These possible combinations of occupant types then need to be multiplied by their possible locations within the vehicle to identify all possible combinations i of occupant types and their locations based on the quantity N from step 22. The identification of these combinations i corresponds to... Figure 3 Step 23 of the flowchart.

[0085] Based on each possible combination i, the centroid of the occupant's accelerator point for each combination i can be determined by weighting the accelerator point with a reference mass associated with the occupant type present at each accelerator point, which corresponds to step 25. For this purpose, it is preferable to determine the location of each occupant's accelerator point in the vehicle reference frame, preferably using the vehicle reference frame with the centroid G already used to locate the wheel center of the tire-wheel assembly. This determination of the occupant's accelerator point location corresponds to step 24.

[0086] Finally, by searching for combination i from step 23, step 26 identifies the exact number of occupants, occupant types, and their locations, which minimizes the distance between the center of mass Ji associated with combination i and the center of mass G associated with the variation in load borne by the tire-wheel assembly. The solution that minimizes the distance to point G is considered the most probable combination i, which allows the identification of the total number of occupants on the vehicle, occupant types, and their locations in predefined positions represented by the vehicle's seats.

[0087] Figure 4 The time evolution of pressure transmitted by a pressure sensor located on the vehicle's tire-wheel assembly is shown. The curve consisting of point 10 is the raw measurement from the pressure sensor, while curve 11 corresponds to the time evolution of pressure after filtering out high-frequency noise. Then... Figure 3 The second curve is used in the block diagram.

[0088] This time-based recording of the internal pressure of the fluid cavity in the tire-wheel assembly begins in the preparatory phase before the occupants board the vehicle. The instant the occupants board corresponds to the abscissa value of point 100, marking the start of the main phase. It can then be seen that from point 100, the internal pressure of the fluid cavity rapidly decreases until point 101, where the pressure decrease stops, and then the pressure even rises to a small extent. Point 101 marks the transition between the fluid work and heat exchange with the outside associated with the occupants boarding the vehicle. The fluid work corresponds to the first transformation of the fluid, which can be likened to an adiabatic transformation, and the heat exchange corresponds to the second transformation of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value at point 101 corresponds to the duration T0. Therefore, the preparatory phase 50 ends at the abscissa value of point 100. This phase precedes the main phase, which is divided into two consecutive phases. The first phase 51 can be likened to an adiabatic transformation of the fluid, which corresponds to the work done by the fluid after one or more occupants board the vehicle. The second phase 52 corresponds to the heat exchange between the fluid and the outside.

[0089] Figure 5 The time evolution of the internal temperature of the fluid cavity is shown. Here, this time evolution is transmitted by a temperature sensor of an electronic device located on the tire-wheel assembly of the vehicle, as shown in curve 12. In the absence of a temperature sensor measurement, an alternative is to estimate the internal temperature, as shown in curve 12', based on both the recorded internal pressure and the evolution of the internal temperature relative to the internal pressure during the adiabatic transformation of the fluid, and the temperature outside the tire-wheel assembly, which serves as the basis for heat exchange between the fluid in the fluid cavity and the external environment of the tire-wheel assembly via a heat exchange coefficient. This heat exchange coefficient takes into account the thermal characteristics of the tire-wheel assembly. In this alternative, curve 70 shows the evolution of the temperature outside the tire-wheel assembly.

[0090] These evolutions 12 and 12' of the internal temperature of the fluid cavity in the tire-wheel assembly begin in the preparatory phase before one or more occupants have boarded the vehicle. The instant of boarding corresponds to the abscissa value of point 100, marking the start of the main phase. It can then be seen that from point 100, the internal temperature of the fluid cavity rapidly decreases until point 101, where the temperature decrease stops, and then the temperature rises to a certain level. Point 101 marks the transition between the fluid work and heat exchange with the outside associated with the boarding of one or more occupants, the fluid work corresponding to a first transformation of the fluid that can be likened to an adiabatic transformation, and the heat exchange corresponding to a second transformation of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value at point 101 corresponds to the duration T0. Therefore, the preparatory phase 50 ends at the abscissa value of point 100. This phase precedes the main phase, which is divided into two consecutive phases. The first phase 51 can be likened to an adiabatic transformation of the fluid, which corresponds to the work done by the fluid after the occupants board the vehicle. The second phase 52 corresponds to the heat exchange between the fluid and the outside.

[0091] Here, the difference between the recorded internal temperature curve 12 and the estimated curve 12' can be seen, which illustrates the inertia unique to temperature sensors. On the other hand, the assumption that the evolution of the fluid's internal pressure and internal temperature during the adiabatic transition may be overestimated. However, the trends between these curves 12 and 12' are very similar. Finally, in this case, the temperature outside the tire-wheel assembly is not measured but determined by extrapolating the internal temperature of the fluid cavity during the preparation phase, which is also a potential source of error. This estimation corresponds to... Figure 5 Line 70 in the figure. The heat exchange coefficient of the tire-wheel assembly can initially be approximated solely by the characteristics of the tire outer casing, for example, by estimating the surface area of ​​the tire exchanging heat with the external environment and the heat exchange coefficient λ, where the surface area represents the outer surface of the tire outer casing, and the heat exchange coefficient λ depends on the thermal properties of the tire material and takes into account different types of heat exchange on the tire outer casing, such as radiation, conduction, and convection. This coefficient λ can be estimated by means of, for example, the evolution of the internal temperature of the fluid cavity during a preparatory stage just before the main stage.

[0092] Figure 6 The time evolution of the internal volume of the fluid cavity is shown. In this case, the time evolution represented by the curve is the output obtained by calculating the volume change using the proposed differential equation, which also takes into account the thermal balance with the external environment.

[0093] This evolution of the internal volume of the fluid cavity in the tire-wheel assembly begins in the preparatory phase before one or more occupants have boarded the vehicle. The instant of boarding corresponds to the abscissa value of point 100, marking the start of the main phase. It can then be seen that from point 100, the internal volume of the fluid cavity rapidly increases until the increase stops at point 101, after which the volume decreases to a certain extent. Point 101 marks the transition between the fluid work associated with boarding and the heat exchange with the outside, the fluid work corresponding to a first transformation of the fluid that can be likened to an adiabatic transformation, and the heat exchange corresponding to a second transformation of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value at point 101 corresponds to the duration T0. Therefore, the preparatory phase 50 ends at the abscissa value of point 100. This phase precedes the main phase, which is divided into two consecutive phases. The first phase 51 can be likened to an adiabatic transformation of the fluid, corresponding to the work done by the fluid after boarding. The second phase 52 corresponds to the heat exchange between the fluid and the outside.

[0094] It should be noted that at the end of stage 51, a good estimate of the volume change of the tire-wheel assembly was obtained, which clearly shows that the work generated by the change in load on the tire-wheel assembly mainly occurs during stage 51. The observed changes or oscillations correspond to fluctuations in the transient phase corresponding to the establishment of thermal equilibrium. Therefore, the method described herein produces continuous measurements of the internal volume of the tire-wheel assembly in the time domain.

[0095] Figure 7 The temporal evolution of the load applied to the electronically equipped tire-wheel assembly is shown. Here, this temporal evolution, represented by curve 14, is the output obtained by calculating the volume change using the proposed differential equation and multiplying it by the flattened stiffness of the tire-wheel assembly, a calculation that takes into account thermal equilibrium with the external environment. The stiffness used here is the locally identified stiffness at the initial pressure on the tire-wheel assembly, the initial load applied to the tire-wheel assembly, and corresponding to the initial temperature. The total stiffness, defined by the proposed formula, can be used, which has already given a good order of magnitude.

[0096] The evolution of the applied load 14 in the fluid cavity of the tire-wheel assembly begins in the preparatory phase before the occupant has boarded the vehicle. The instant of boarding corresponds to the abscissa value of point 100, marking the start of the main phase. It can then be seen that from point 100, the load rapidly decreases until it stabilizes at point 101, after which it diminishes to a certain extent. Point 101 marks the transition between the fluid work and heat exchange with the outside associated with the occupant's boarding, the fluid work corresponding to a first transformation of the fluid that can be likened to an adiabatic transformation, and the heat exchange corresponding to a second transformation of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value at point 101 corresponds to the duration T0. Therefore, the preparatory phase 50 ends at the abscissa value of point 100. This phase precedes the main phase, which is divided into two consecutive phases. The first phase 51 can be likened to an adiabatic transformation of the fluid, which corresponds to the work done by the fluid after boarding. The second phase 52 corresponds to the heat exchange between the fluid and the outside.

[0097] It should be noted that at the end of stage 51, a good estimate of the change in load applied to the tire-wheel assembly was obtained, clearly indicating that the work generated by the load change mainly occurred during stage 51. The observed changes or oscillations correspond to fluctuations in the transient phase corresponding to the establishment of thermal equilibrium. Therefore, the method described herein produces a continuous measurement of the temporal change in load applied to the tire-wheel assembly in the time domain. Curve 80 corresponds to the measurement of the overload applied to the tire-wheel assembly of the trailer via a ground-based weighbridge. In summary, the proposed method captures the change in applied load very well.

Claims

1. A method for estimating the change in load on the tire-wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, the method comprising the steps of: In the preparatory stage - Each tire wheel assembly of the vehicle is equipped with at least one pressure sensor, which is capable of measuring the internal pressure of the fluid cavity of the tire wheel assembly defined by the tire outer tube and the wheel; - Determine the initial load Z1 applied to each tire wheel assembly equipped with a pressure sensor on the vehicle; - Determine the initial inflation pressure P1 of the fluid chamber of each tire wheel assembly equipped with a pressure sensor in the vehicle; - Determine the initial internal temperature T1 of the fluid chamber of each tire wheel assembly equipped with a pressure sensor in the vehicle; - The initial volume V1 of each tire-wheel assembly equipped with a pressure sensor is evaluated using a first function, the parameters of which include the volume V0 of the fluid cavity of the tire-wheel assembly when unloaded and inflated to an initial pressure P1, and the flattening stiffness K of the tire per unit volume of the tire-wheel assembly. P ; - The number of moles of fluid n in the fluid chamber of each tire wheel assembly equipped with a pressure sensor was evaluated using a model that takes into account inflation pressure P1, initial volume V1, and temperature T1. - Determine the evolution of the internal temperature T of the fluid cavity based on the internal pressure P during the adiabatic transformation of each tire wheel assembly that is inflated, subjected to a load Z1, and equipped with at least one pressure sensor. During the main phase: - Ensure that at least one occupant is in the vehicle; - Record the internal pressure P of the fluid chamber of each tire wheel assembly equipped with a pressure sensor at a sampling frequency F1; - The internal temperature T of the fluid cavity of each tire wheel assembly equipped with a pressure sensor is determined by utilizing the evolution law determined in the preparatory stage; - Using a determined internal temperature T and recorded internal pressure P, and employing a model of a fluid undergoing an adiabatic transformation, the intermediate volume change ΔV of each tire-wheel assembly equipped with a pressure sensor is evaluated, where the fluid behaves as an ideal gas; and - A second function is used to estimate the load variation ΔZ experienced by each tire-wheel assembly equipped with a pressure sensor. The parameters of this second function include the intermediate volume variation ΔV and the flattened stiffness K per unit volume of the tire in the tire-wheel assembly. P .

2. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, as described in claim 1, wherein, In the preparation phase, each tire wheel assembly equipped with a pressure sensor in the vehicle includes a temperature sensor capable of measuring the temperature of the fluid cavity. The method includes, in the main phase, a step of recording the internal temperature T of the fluid cavity of each tire wheel assembly equipped with a pressure sensor at a sampling frequency F2. The method includes, taking into account the recorded internal temperature T, a second step of evaluating the intermediate change ΔV2 of the volume of each tire wheel assembly equipped with a pressure sensor using a model of a fluid that behaves as an ideal gas and is in thermal equilibrium with the environment outside the fluid cavity.

3. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 and 2, wherein, Prior to the main steps, each tire wheel assembly equipped with a pressure sensor is in a state of thermomechanical stability.

4. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 to 3, wherein, Pressure and / or temperature sensors are located in a subspace of a closed fluid cavity defined by the tire outer tube and the wheel.

5. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 to 4, wherein, The sampling frequency F1 is between 0.1 Hz and 10 Hz.

6. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 2 to 5, wherein, The sampling frequency F2 is lower than the sampling frequency F1.

7. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 to 6, wherein, The determination of the initial volume V0 takes into account the geometry of the rim and the geometry of the unloaded tire mounted on the rim and inflated to a reference pressure P0. Preferably, the reference pressure P0 is the initial pressure P1.

8. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, as described in claim 7, wherein, The geometry of the tire and / or the rim is determined using the tire and / or wheel identifiers of the tire and / or wheel assembly equipped with pressure sensors. Preferably, the tire and / or wheel identifiers are obtained by radio frequency interrogation of electronics located on the tire and wheel assembly.

9. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 to 8, wherein, The load Z on each tire-wheel assembly equipped with a pressure sensor can be estimated using the following formula: [Mathematical Expression 1] ， Among them, K PP It is the aerodynamic flattening stiffness per unit volume of the tire in the tire-wheel assembly.

10. The method for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 1 to 9, wherein, The volume change ΔV of each tire-wheel assembly equipped with a pressure sensor is estimated by solving the following differential equation: [Mathematical Equation 2] ,and [Mathematical Expression 3] ， Where P is the internal pressure of the fluid cavity, V is the internal volume of the fluid cavity, and T is the internal temperature of the fluid cavity.

11. A method for estimating the number and location of occupants in a vehicle, the method comprising, according to any one of claims 1 to 10, a method for estimating the change in load on the tire-wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, wherein, The method, which determines the vehicle's track width and wheelbase, as well as the average occupant bearing point on each seat, includes the following steps: - The total load P generated by at least one occupant is determined by summing the load variation ΔZ borne by each tire wheel assembly equipped with a pressure sensor in the vehicle; - Determine the center of gravity G of the total load P generated by at least one occupant, and obtain the coordinates of the center of gravity G in the vehicle-related reference frame R; - The average number of occupants N is determined as the ratio between the total load Z generated by at least one occupant and a reference value REF, wherein the reference value REF preferably represents the average weight of an adult; - Identify the combination of positioning and occupant type on each seat of a vehicle that matches the average number of occupants N; - For each identified combination of occupants, determine the coordinates of the center of gravity J of all occupants in reference frame R; and - Identify the best possible combination that minimizes the distance between the center of gravity G and the center of gravity J.

12. The method for estimating the number and location of occupants in a vehicle according to claim 11, wherein, Passenger types are included in groups containing adult males, adult females, adolescents, and children.

13. A method (1000) for implementing the method (1000) for estimating the change in load on the tire-wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle according to any one of claims 1 to 10 and / or a system (2000) for implementing the method (2000) for estimating the number and location of occupants of a vehicle according to any one of claims 11 and 12, the system (2000) comprising: - A vehicle (2001) capable of accommodating at least one occupant in a seat, wherein each tire wheel assembly (2006) of the vehicle is equipped with an electronic device (2007). - The electronic device (2007) includes at least one pressure sensor, at least one electronic chip, at least one storage space capable of recording signals from the sensor, and at least one first radio frequency communication device (2101) capable of transmitting. - At least one computing device (2002); and - At least one display device (2003) includes at least one second radio frequency communication device (2102) capable of receiving.

14. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, as described in claim 13, and / or the system (2000) for implementing a method for estimating the number and location of occupants of a vehicle, wherein, The system (2000) includes an analysis device (2004) capable of analyzing results output by at least one computing device (2002).

15. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 and 14, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, At least one computing device (2002) includes at least one third radio frequency communication device (2103) capable of transmitting / receiving.

16. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, as described in claim 15, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, At least one analysis device (2004) includes at least one fourth radio frequency communication device (2104) capable of transmitting / receiving.

17. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 to 16, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, The system (2000) includes at least one reading device (2005) capable of reading data contained in at least one storage space of an electronic device (2007), and the at least one reading device (2005) includes at least one fifth communication device (2105) capable of receiving data.

18. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 to 17, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, Communication performed by the communication devices (2101, 2102, 2103, 2104, 2105) between a portion of the communication and the elements included in the group comprising the electronic device (2007), the at least one computing device (2002), the at least one display device (2003), the at least one analysis device (2004), and the at least one reading device (2005) is performed using UHF radio waves, preferably using BLE.

19. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 to 18, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, The at least one display device (2003) is included in the group comprising a telephone, a computer, and a human-machine interface located on the vehicle (2001), preferably on the dashboard of the vehicle (2001).

20. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 to 19, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, At least one part of a reading device (2005) is located on the vehicle (2001).

21. The method (1000) for estimating the change in load on the tire and wheel assembly of a vehicle caused by at least one occupant boarding a stationary vehicle, according to any one of claims 13 to 20, and / or the system (2000) for implementing the method for estimating the number and location of occupants of a vehicle, wherein, A portion of at least one computing device (2002) and / or a portion of at least one analysis device (2004) is located on the vehicle (2001), preferably on the tire wheel assembly (2006).

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