Tyre behaviour modelling

Abstract

A method of determining a set of temperature-dependent scaling factors for correcting a calculated force or moment acting on the tread surface of a tyre during running, comprises the steps of: measuring values of the actual force or moment acting on the tread surface in the contact patch of a tyre during running; measuring values of a temperature associated with the tyre, or estimating values of a temperature associated with the tyre based on values of one or more measured parameters associated with the tyre; calculating values of the theoretical force or moment acting on the tread surface of the tyre during running using a mathematical model; and determining a set of temperature-dependent scaling factors for correcting the calculated theoretical force or moment by comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated temperature values.

Description

[0001] Tyre Behaviour Modelling

[0002] The invention relates to tyre behaviour modelling, and in particular to a thermomechanical model for predicting tyre behaviour while taking into account the effect temperature has on the tyre’s behaviour during rolling conditions.

[0003] Various different ways of modelling tyre behaviour during running have been used over the years, but some of the most widely used models are the Pacejka “Magic Formula” tyre models. These models allow forces or moments at the contact patch such as lateral force, longitudinal force and aligning moment to be calculated. These forces are typically plotted against varying slip angle or slip ratio of the tyre.

[0004] However, the tyre models used up to now do not take account of many real-world conditions which affect the tyre’s performance.

[0005] The invention aims to mitigate at least one the problems associated with the prior art.

[0006] A first aspect of the invention provides a method of determining a set of temperaturedependent scaling factors for correcting a calculated force or moment acting on the tread surface of a tyre during running, comprising the steps of: measuring values of the actual force or moment acting on the tread surface in the contact patch of a tyre during running; measuring values of a temperature associated with the tyre, or estimating values of a temperature associated with the tyre based on values of one or more measured parameters associated with the tyre; calculating values of the theoretical force or moment acting on the tread surface of the tyre during running using a mathematical model; and determining a set of temperature-dependent scaling factors for correcting the calculated theoretical force or moment by comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated temperature values. In this way, the force or moment acting normal to the tyre radial direction in the contact patch can be corrected to take account of tyre temperatures and obtain a tyre model which has greater accuracy than a typical tyre model.

[0007] The tread surface tyre temperatures may be measured on the outer radial tread surface of the tread elements; the inner temperatures may be measured at different points of inner liner.

[0008] Alternatively, instead of being a method of determining a set of temperature-dependent scaling factors, the method may be a method of determining a set of wear-dependent scaling factors. In such a method, instead of the step of measuring a temperature associated with the tyre, or estimating a temperature associated with the tyre, the method may comprise the step of measuring values of tread depth reduction of the tyre (tread loss), or estimating values of tread loss of the tyre based on values of one or more measured parameters associated with the tyre. Furthermore, instead of the step of determining the set of temperature-dependent scaling factors, the method may comprise the step of determining a set of wear-dependent scaling factors for correcting the calculated theoretical force or moment by comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated tread loss values.

[0009] Preferably, in the method, the comparing is done by calculating the ratio between the calculated theoretical force or moment values and the measured actual force or moment values, and determining the relationship between the calculated ratio and the measured or estimated temperature values.

[0010] Preferably, in the force or moment measuring step and in the temperature measuring or estimating step, the actual force or moment and the temperature or one or more parameters associated with the tyre are measured on a forces and moments tyre test rig, but other ways of measuring or estimating may be possible. For example, it may be possible to measure or estimate these values during a road testing step.

[0011] Preferably, the method further comprises a road testing step of measuring values of the temperature associated with the tyre while the tyre is installed on a vehicle which is driven on a road, for example on a test track. Preferably, in the temperature measuring or estimating step, at least one temperature value is measured or estimated which is the same as a temperature value obtained in the road testing step. In this way, it can be ensured that the scaling factors are determined at temperatures that a tyre would experience during road use.

[0012] Preferably: during the road testing step, values of another parameter associated with the tyre are measured, and while the tyre is installed on the tyre testing rig, the values of the temperature associated with the tyre are measured, and values of the other parameter associated with the tyre are measured, and the method further comprising the step of determining the relationship between the temperature measured during the road testing step and the other parameter measured during the road testing step using the values of the temperature measured on the tyre test rig and the other parameter measured on the tyre test rig, and using the result to determine the set of temperature-dependent scaling factors. In this way, the scaling factors can be made dependent on the temperature during the road testing step which is estimated from the other parameter measured during the road testing step. Therefore, when using the scaling factors, it may not be necessary to measure the temperature directly. The other parameter may be, for example, roadway speed or vertical load on the tyre.

[0013] The method may include the step of determining the relationship between the measured temperature associated with the tyre and another measured parameter associated with the tyre. In this way, the temperature associated with the tyre can be estimated based on the other measured parameter.

[0014] The temperature associated with the tyre may be estimated based on at least one of the following parameters: the measured roadway speed, the measured lateral force on the tyre, the measured longitudinal force on the tyre, the slip angle, brake temperature, and tyre ambient air temperature.

[0015] Preferably, the method further comprises the step of measuring values of tread loss of the tyre, or estimating values of tread loss of the tyre based on values of one or more measured parameters associated with the tyre, wherein the step of determining the set of temperature-dependent scaling factors includes comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated tread loss values.

[0016] The tread loss of the tyre may be estimated based on at least one of the following parameters: the measured lateral force on the tyre, the measured longitudinal force on the tyre, the slip amount or angle, and the usage history of the tyre. When based on the usage history of the tyre, there may be a starting point of tread loss (which may be zero tread loss) to which additional wear amount (tread depth reduction) is added based on measured time histories of forces and slippages.

[0017] In the step of estimating tread loss of the tyre, the tread loss may be estimated based on the tyre compound.

[0018] A second aspect of the invention provides a computer-implemented method of calculating the force or moment acting on the tread surface of a tyre during running, comprising the steps of: calculating the force or moment acting on the tread surface of a tyre during running using a mathematical tyre model; calculating a set of scaling factors based on at least one temperature associated with the tyre; and correcting the calculated force or moment using the set of scaling factors.

[0019] The preferable features of the first aspect are equally applicable to the second aspect and vice versa.

[0020] The step of calculating the set of scaling factors can be carried out before the step of calculating the force or moment.

[0021] Alternatively, instead of calculating a set of scaling factors based on at least one temperature associated with the tyre, the method may comprise the step of calculating a set of scaling factors based on the wear amount (tread loss) of the tyre.

[0022] The method may be carried out in the ECU of a vehicle on which the tyre is mounted, or in a vehicle simulator. Alternatively, the method may be carried out in the cloud and the corrected calculated force or moment may be transmitted back to a vehicle on which the tyre is mounted.

[0023] The set of scaling factors represents how the force or moment acting on the tyre varies with temperature, and allows the calculated force or moment to be corrected according to the temperature of the tyre.

[0024] Preferably, the force or moment acting on the tyre is the lateral or longitudinal force or aligning moment. The longitudinal force may be braking force or traction force. The lateral or longitudinal force or aligning moment acting on the tread surface of the tyre may be calculated in terms of a force such as the vertical load.

[0025] The lateral force may be calculated based on the vertical load on the tyre and slip angle and camber angle.

[0026] The longitudinal force may be calculated based on the vertical load on the tyre and slip ratio.

[0027] The aligning moment may be calculated based on the vertical load on the tyre and slip angle, and optionally tyre camber angle.

[0028] The method may comprise the step of estimating the vertical load on the tyre based on the output of a vehicle body accelerometer and by vehicle static payload distribution on the four wheels.

[0029] The method may comprise the step of estimating the slip angle of the tyre based on the output of an inertial measurement unit and lateral velocity unit. The inertial measurement unit may measure yaw angle, while a vehicle speeds unit may measure longitudinal body speed and / or lateral body speed.

[0030] The method may comprise the step of estimating the slip ratio of the tyre based on the output of a wheel angular velocity unit. The wheel angular velocity unit may measure wheel angular speeds.

[0031] Preferably, the force or moment acting on a tyre is calculated using a Pacejka Magic Formula tyre model. Preferably, the at least one temperature comprises an outer surface temperature of the tyre.

[0032] Preferably, the outer surface temperature of the tyre is a tread surface temperature of the tyre.

[0033] Preferably, the outer surface temperature of the tyre is estimated based on at least one of: the roadway speed, the lateral force on the tyre, the longitudinal force on the tyre, the slip angle, brake temperature, and tyre ambient air temperature.

[0034] Tire forces and slippages (slip angles, slip ratios) allow friction power to be computed which in turn is representative of tyre temperature.

[0035] Alternatively, the outer surface temperature of the tyre may be measured using a thermal sensor which may be installed on a vehicle body.

[0036] Preferably, the at least one temperature comprises an inner liner temperature of the tyre, and preferably the at least one temperature comprises at least one of a brake temperature and a tyre ambient air temperature.

[0037] Preferably, at least one of the inner liner temperature of the tyre, the brake temperature and the tyre ambient air temperature is measured using a thermal sensor which may be installed on a vehicle body.

[0038] Preferably, the set of scaling factors is calculated based on the wear of the tyre.

[0039] The wear of the tyre may be the tread loss (wear amount) of the tyre. The tread loss may be calculated based on the wear energy and / or ease of wear of the tyre tread compound. The wear energy may be calculated from the slip amount (for example, slip angle times vehicle speed) times shear stress or total force (for example, lateral force) in the contact patch.

[0040] The wear of the tyre may be estimated based on the usage history of the tyre. For example, the usage history may include at least one of the following: distance travelled by the tyre, and wear energy experienced by the tyre over time. The tread depth of the tyre may be measured using an optical sensor. From this, the tread loss of the tyre may be calculated.

[0041] The wear of the tyre may be estimated based on the tyre compound.

[0042] A third aspect of the invention provides a device configured to carry out the method of the first or second aspects.

[0043] The device may include a memory. The memory may store information for calculating the set of scaling factors based on the at least one temperature associated with the tyre. The memory may be configured to store information on the usage history of the tyre. Alternatively, the information on the usage history may be stored in a memory in a cloud server.

[0044] A fourth aspect of the invention provides a system including the device of the third aspect and at least one sensor configured to measure vehicle body acceleration, body speeds, roadway speed, brake temperature or ambient air temperature.

[0045] The at least one sensor may be an accelerometer which may be installed on a vehicle body, or may be a thermal sensor which may be installed on a vehicle body.

[0046] The at least one sensor may be provided in an inertial measurement unit.

[0047] Preferably, the at least one temperature associated with the tyre is calculated based on the output of the at least one sensor, and preferably the force or moment acting on the tyre is calculated based on the output of the at least one sensor.

[0048] For example, vertical load, slip angle and / or slip ratio may be calculated based on the output of the at least one sensor, and the force or moment acting on the tyre may be calculated based on that.

[0049] A fifth aspect of the invention provides a method of calculating the force or moment acting on the tread surface of a tyre during running, comprising: determining a set of scaling factors using the method of the first aspect, and calculating the force or moment acting on the tread surface of a tyre during running using the method of the second aspect.

[0050] The method is preferably carried out in the ECU of a vehicle, or in a vehicle simulator.

[0051] A sixth aspect of the invention provides a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of the first or second aspects.

[0052] A seventh aspect of the invention provides a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method of the first or second aspects.

[0053] The preferable features of any of the first and seventh aspects are equally applicable to any other of the first to seventh aspects.

[0054] Preferred embodiments of the invention will now be described, purely by way of example, with reference to the drawings in which:

[0055] Fig. 1 is a graph showing lateral (cornering) force plotted against slip angle;

[0056] Fig. 2 is a flow chart showing the procedure for determining a set of scaling factors according to an embodiment of the invention;

[0057] Fig. 3 is a block diagram showing a technical architecture of a server X; and

[0058] Fig. 4 is a block diagram showing a technical architecture of a communication device 1.

[0059] An example of a Pacejka Magic Formula tyre model (“MF tyre model”) for lateral force or cornering force is given below as Equation 1.

[0060] Where:

[0061] F is the lateral force in N; B, C, D, E are dimensionless coefficients, some of which are dependent on vertical force in kN, camber angle in degrees, and / or slip angle in degrees; a is dependent on slip angle in degrees; and

[0062] S is vertical shift.

[0063] Using this equation, the lateral force can be predicted and plotted against varying slip angle, for example. However, in real-world conditions, when the temperature of the tyre increases and the tyre becomes hot, the lateral force curve changes and the maximum lateral force that can be achieved by the tyre becomes lower.

[0064] Fig. 1 is a graph showing lateral (cornering) force plotted against slip angle. Fig. 1 shows an upper curve for when the tyre is in nominal conditions, and a lower curve for when the tyre is in decayed conditions, when the temperature has increased. The data for both curves was obtained from an indoor test bench, with the lower curve for decayed conditions being obtained by increasing the temperature of the tread compound. The arrows in the graph show the direction in which the curve gradient, or peak force slip angle, moves as temperature increases. In particular, the arrow on the left shows the drop in curve gradient at high slip angles. The middle arrow shows how the peak force slip angle moves from around -6 or -7 degrees for the nominal conditions curve to around -5 degrees for the decayed conditions curve. The arrow on the right shows the direction in which the curve gradient moves as temperature increases for low slip angles.

[0065] Using a typical MF tyre model will give a curve which is a close approximation to the upper (nominal conditions) curve. However, the curve from a typical MF tyre model will not be a close approximation to the lower (decayed conditions) curve (at least for slip angles above -5 degrees). On the other hand, the temperature-corrected MF tyre model can give a curve which is a closer approximation to the lower (decayed conditions) curve for the particular increased temperature. The curve from the temperature-corrected MF tyre model would be a closer model of the real-world behaviour of the tyre because it takes into account temperature changes of the tyre under real-world conditions.

[0066] Fig. 2 is a flow chart showing a full procedure for determining a set of scaling factors for correcting a calculated force or moment (in this case, a lateral force) acting on the tread surface of a tyre during running. However, the procedure is explanatory and not all the steps of the procedure are essential. The procedure involves outdoor track testing, indoor testing on a tyre testing machine and data processing of the data obtained during the outdoor and indoor testing. The data processing produces a set of scaling factors which depends on temperature (in the example, several temperatures associated with the tyre) which can be used to correct the Pacejka Magic Formula tyre model to obtain a more accurate representation of the tyre’s behaviour under real-world conditions.

[0067] Referring to Fig. 2, 101 refers to the outdoor testing part of the procedure. During outdoor testing, various temperatures associated with the tyre are measured as a vehicle (passenger car) is driven around a test track or a road. Data on how the temperatures vary with time is recorded. The temperatures measured are tread surface temperature of the tyre, inner liner temperature of the tyre, brake temperature and ambient air temperature (respectively, TSUrf, Tinner, Tbrakes, Tamb). The tyre wear level and appearance is also evaluated. Furthermore, values of the tyre inputs such as the tyre vertical load (Fz e) slip angles, slip ratios and roadway speed (Vxve) are estimated.

[0068] Next, in 102, indoor testing on a tyre testing machine or rig is conducted. The following are measured and how they vary with time is recorded: the tread surface temperature of the tyre, inner liner temperature of the tyre (TSUrf, Tinner) , and tyre inputs such as vertical force or load (FZFT), lateral force (Fy), longitudinal force (Fx) , and roadway speed (VXFT During indoor testing, specific procedures are implemented to reproduce tyre temperatures and wear levels aligned with those experienced during outdoor testing.

[0069] It should be noted that it would in principle be possible to undertake the procedure without the outdoor testing part 101 and obtain sufficient data to produce a set of temperature-dependent scaling factors based on indoor testing alone. However, it is preferred to involve some outdoor testing, because the temperatures in the indoor testing environment are not necessarily closely representative of real-world outdoor driving conditions. Therefore, in the present embodiment, both outdoor and indoor testing are conducted, and a transfer function is produced to convert indoor data into an outdoor prediction, as described below.

[0070] Next, in 103, processing of the data obtained in 101 and 102 is conducted to obtain the transfer function. Assuming thermal equivalence of the temperatures measured during outdoor testing and indoor testing, and comparing data for Fzi / eand Fzprand \ / xyeand VXFT, an algorithm is used to obtain a transfer function. Next, in 104, a thermal model is obtained. The thermal model is not essential, but is useful when it is not possible to measure the tread surface temperature of the tyre (TSUrf), for example. The thermal model allows this temperature to be estimated from other parameters which are easier to measure. To obtain the thermal model, TSUrf is taken as a function of tyre inputs such as Fzve, Vxve, Fy, Fx, Tbrakes, Tamb, and the relationship between TSUrf and these other variables is determined to obtain thermal model.

[0071] Next, in 105, a force model is obtained. In this embodiment, it is a lateral force model, but instead it could be a longitudinal force model or an aligning moment model. First, values of theoretical Fyare calculated using the typical MF model. Then, the values of theoretical Fyare divided by the values of Fy measured in 102 to obtain a set of raw scaling factors. This involves dividing plural theoretical Fyvalues by plural measured Fy values for the same slip angle, respectively. (Alternatively, instead of using measured Fy values directly, the Fymay be estimated from those measured in 102, for example by interpolation.) Then, assuming that the set of raw scaling factors is a function of TSUrf, Tinner, Tbrakes, and Tamb, the relationship between the set of raw scaling factors and these other variables is determined to obtain a set of temperature-dependent scaling factors AKY, AMUY, thereby completing the force model which has greater accuracy than the typical MF model.

[0072] It should be noted that the embodiment described above provides a model which takes into account external heat generation in Tbrakes, and Tams as this can provide a more accurate model, but this is not essential. The model could be based on only TSUrf for example, or on TSUrf and Tinner.

[0073] Once the set of temperature-dependent scaling factors has been determined, the force model can be used by i) calculating Fyusing the typical MF model, ii) using TSUrf and the set of temperature-dependent scaling factors to calculate the set of actual scaling factors for correcting the calculated Fy, and iii) multiplying the calculated Fy to obtain a corrected value for Fy. If desired, multiple corrected values can be obtained and plotted against, for example, slip angle, to give a plot of the kind shown in Fig. 1. From here it is easy to see, for instance, the maximum lateral force for the nominal curve is around 8500N at around -6 or -7 degrees, whereas for the decayed curve when temperature effects are considered, the maximum lateral force for the decayed curve is around 8000N at around -5 degrees. During track testing when the car is driven aggressively round a test track, it would be expected that the decayed conditions curve would become lower for every lap that is completed as the temperature of the tyres rises.

[0074] The force model may be enhanced by taking account of the wear of the tyre. In this regard, during indoor testing in 102, the wear of the tyre may be measured (for example, by hand) at various points during the testing procedure when the corresponding tyre inputs are being measured by the tyre testing machine. The testing may be conducted so that forces at different levels of wear are obtained while the tyre temperature is maintained constant. Then, when obtaining the force model in 105, assuming that the set of raw scaling factors is a function of wear in addition to TSUrf, Tinner, Tbrakes, and Tams, the relationship between the set of raw scaling factors and these other variables is determined to obtain a set of scaling factors which is dependent on temperature as well as wear.

[0075] The enhanced-accuracy force model has various potential uses. It can be used, for example in the design of tyres; in the ECU of a vehicle to inform or warn the driver of how the tyres are behaving; or in vehicle simulations to simulate more accurately how the tyres behave under real-world conditions.

[0076] Taking use in the ECU of a vehicle as an example, the ECU may include software which performs a method of calculating the force acting on the tread surface of a tyre during running using the enhanced-accuracy force model. Here, the ECU calculates the force acting on the tyre using an MF equation. Then, rather than directly measure the outer surface temperature of the tyre, the ECU typically will estimate the outer surface temperature of the tyre based on the roadway speed, the lateral force on the tyre, the longitudinal force on the tyre, the slip angle, brake temperature, and tyre ambient air temperature. These parameters are themselves measured or estimated. Then, based on the estimated outer surface temperature of the tyre, a set of scaling factors for that particular temperature will be calculated from the set of temperature-dependent scaling factors. Next, the ECU will correct the calculated force acting on the tyre using the set of scaling factors to obtain a corrected force for the estimated temperature. The ECU may then be configured to warn the driver if, for example, the tyres are providing considerably less lateral force than normal because of their higher temperature, or if the vehicle is being driven in a way that the lateral force required to corner is likely to exceed that which the tyre can produce at its current or a predicted future temperature. Where the model is enhanced by taking account of the wear of the tyre, the wear of the tyre may be estimated using the wear energy and ease of wear of the tyre compound. The wear energy may be calculated from the slip amount and shear stress in the contact patch, with the shear stress being calculated from the force acting on the tread surface in the contact patch.

[0077] The ECU includes a memory on which is stored information for calculating the set of scaling factors. In this embodiment, an equation defining the relationship between the set of scaling factors and the temperature is stored in the memory, which allows the processor of the ECU to calculate a set of scaling factors for any likely temperature. In addition, the uncorrected MF model or equation is stored in the memory, and an equation defining the relationship between the uncorrected MF model and the corrected model using the set of scaling factors is stored in the memory.

[0078] As used in this application, the terms “component,” “module,” “engine,” “system,” “apparatus,” “interface,” or the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and / or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and / or thread of execution and a component may be localized on one computer and / or distributed between two or more computers.

[0079] Furthermore, the claimed subject matter may be implemented as a method, apparatus, or article of manufacture using standard programming and / or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. For instance, the claimed subject matter may be implemented as a computer-readable medium embedded with a computer executable program, which encompasses a computer program accessible from any computer- readable storage device or storage media. For example, computer readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips), optical disks (e.g., compact disk (CD), digital versatile disk (DVD)), smart cards, and flash memory devices (e.g., card, stick, key drive). Fig. 3 is a block diagram showing a technical architecture of a server X.

[0080] The technical architecture includes a processor 222 (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage 224 (such as disk drives), read only memory (ROM) 226, random access memory (RAM) 228. The processor 222 may be implemented as one or more CPU chips. The technical architecture may further comprise input / output (I / O) devices 230, and network connectivity devices 232.

[0081] The secondary storage 224 is typically made up of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM 228 is not large enough to hold all working data. Secondary storage 224 may be used to store programs which are loaded into RAM 228 when such programs are selected for execution.

[0082] In this embodiment, the secondary storage 224 has an order processing component 224a comprising non-transitory instructions operative by the processor 222 to perform various operations of the method of the present disclosure. The ROM 226 is used to store instructions and perhaps data which are read during program execution. The secondary storage 224, the RAM 228, and / or the ROM 226 may be referred to in some contexts as computer readable storage media and / or non-transitory computer readable media.

[0083] I / O devices 230 may include printers, video monitors, liquid crystal displays (LCDs), plasma displays, touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, or other well-known input devices.

[0084] The network connectivity devices 232 may take the form of modems, modem banks, Ethernet cards, universal serial bus (USB) interface cards, serial interfaces, token ring cards, fiber distributed data interface (FDDI) cards, wireless local area network (WLAN) cards, radio transceiver cards that promote radio communications using protocols such as code division multiple access (CDMA), global system for mobile communications (GSM), long-term evolution (LTE), worldwide interoperability for microwave access (WiMAX), near field communications (NFC), radio frequency identity (RFID), and / or other air interface protocol radio transceiver cards, and other well-known network devices. These network connectivity devices 232 may enable the processor 222 to communicate with the Internet or one or more intranets. With such a network connection, it is contemplated that the processor 222 might receive information from the network, or might output information to the network in the course of performing the above-described method operations. Such information, which is often represented as a sequence of instructions to be executed using processor 222, may be received from and outputted to the network, for example, in the form of a computer data signal embodied in a carrier wave.

[0085] The processor 222 executes instructions, codes, computer programs, scripts which it accesses from hard disk, floppy disk, optical disk (these various disk based systems may all be considered secondary storage 224), flash drive, ROM 226, RAM 228, or the network connectivity devices 232. While only one processor 222 is shown, multiple processors may be present. Thus, while instructions may be discussed as executed by a processor, the instructions may be executed simultaneously, serially, or otherwise executed by one or multiple processors.

[0086] Although the technical architecture is described with reference to a computer, it should be appreciated that the technical architecture may be formed by two or more computers in communication with each other that collaborate to perform a task. For example, but not by way of limitation, an application may be partitioned in such a way as to permit concurrent and / or parallel processing of the instructions of the application. Alternatively, the data processed by the application may be partitioned in such a way as to permit concurrent and / or parallel processing of different portions of a data set by the two or more computers. In an embodiment, virtualization software may be employed by the technical architecture 220 to provide the functionality of a number of servers that is not directly bound to the number of computers in the technical architecture 220. In an embodiment, the functionality disclosed above may be provided by executing the application and / or applications in a cloud computing environment. Cloud computing may comprise providing computing services via a network connection using dynamically scalable computing resources. A cloud computing environment may be established by an enterprise and / or may be hired on an as-needed basis from a third party provider.

[0087] It is understood that by programming and / or loading executable instructions onto the technical architecture, at least one of the CPU 222, the RAM 228, and the ROM 226 are changed, transforming the technical architecture in part into a specific purpose machine or apparatus having the novel functionality taught by the present disclosure. It is fundamental to the electrical engineering and software engineering arts that functionality that can be implemented by loading executable software into a computer can be converted to a hardware implementation by well-known design rules.

[0088] Fig. 4 is a block diagram showing a technical architecture of a communication device 1. It is envisaged that in embodiments, the communication device 1 will be a smartphone or tablet device.

[0089] The technical architecture includes a processor 322 (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage 324 (such as disk drives or memory cards), read only memory (ROM) 326, random access memory (RAM) 328. The processor 322 may be implemented as one or more CPU chips. The technical architecture further comprises input / output (I / O) devices 330, and network connectivity devices 332.

[0090] The I / O devices comprise a user interface (Ul) 330a, a camera 330b and a geolocation module 330c. The Ul 330a may comprise a touch screen, keyboard, keypad or other known input device. The camera 330b allows a user to capture images and save the captured images in electronic form. The geolocation module 330c is operable to determine the geolocation of the communication device using signals from, for example global positioning system (GPS) satellites.

[0091] The secondary storage 324 is typically made up of a memory card or other storage device and is used for non-volatile storage of data and as an over-flow data storage device if RAM 328 is not large enough to hold all working data. Secondary storage 324 may be used to store programs which are loaded into RAM 328 when such programs are selected for execution.

[0092] In this embodiment, the secondary storage 324 has an order generation component 324a, comprising non-transitory instructions operative by the processor 322 to perform various operations of the method of the present disclosure. The ROM 326 is used to store instructions and perhaps data which are read during program execution. The secondary storage 324, the RAM 328, and / or the ROM 326 may be referred to in some contexts as computer readable storage media and / or non-transitory computer readable media. The network connectivity devices 332 may take the form of modems, modem banks, Ethernet cards, universal serial bus (USB) interface cards, serial interfaces, token ring cards, fiber distributed data interface (FDDI) cards, wireless local area network (WLAN) cards, radio transceiver cards that promote radio communications using protocols such as code division multiple access (CDMA), global system for mobile communications (GSM), long-term evolution (LTE), worldwide interoperability for microwave access (WiMAX), near field communications (NFC), radio frequency identity (RFID), and / or other air interface protocol radio transceiver cards, and other well-known network devices. These network connectivity devices 332 may enable the processor 322 to communicate with the Internet or one or more intranets. With such a network connection, it is contemplated that the processor 322 might receive information from the network, or might output information to the network in the course of performing the above-described method operations. Such information, which is often represented as a sequence of instructions to be executed using processor 322, may be received from and outputted to the network, for example, in the form of a computer data signal embodied in a carrier wave.

[0093] The processor 322 executes instructions, codes, computer programs, scripts which it accesses from hard disk, floppy disk, optical disk (these various disk based systems may all be considered secondary storage 324), flash drive, ROM 326, RAM 328, or the network connectivity devices 332. While only one processor 322 is shown, multiple processors may be present. Thus, while instructions may be discussed as executed by a processor, the instructions may be executed simultaneously, serially, or otherwise executed by one or multiple processors.

[0094] Preferred embodiments of the invention have been described purely by way of example, and various modifications, additions and / or omissions will present themselves to one skilled in the art, all of which form part of the invention.

Claims

AMENDED CLAIMS received by the International Bureau on 25 November 2024 (25.11 .204)1 . A method of determining a set of temperature-dependent scaling factors for correcting a calculated force or moment acting on the tread surface of a tyre during running, comprising the steps of: measuring values of the actual force or moment acting on the tread surface in the contact patch of a tyre during running; measuring values of a temperature associated with the tyre, or estimating values of a temperature associated with the tyre based on values of one or more measured parameters associated with the tyre; calculating values of the theoretical force or moment acting on the tread surface of the tyre during running using a mathematical model; and determining a set of temperature-dependent scaling factors for correcting the calculated theoretical force or moment by comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated temperature values.

2. A method of claim 1 , wherein, in the force or moment measuring step and in the temperature measuring or estimating step, the actual force or moment and the temperature or one or more parameters associated with the tyre are measured on a forces and moments tyre test rig.

3. A method of claim 1 or 2, further comprising a road testing step of measuring values of the temperature associated with the tyre while the tyre is installed on a vehicle which is driven on a road.

4. A method of claim 3 when dependent on claim 2, wherein: during the road testing step, values of another parameter associated with the tyre are measured, and while the tyre is installed on the tyre test rig, the values of the temperature associated with the tyre are measured, and values of the other parameter associated with the tyre are measured, and the method further comprising the step of determining the relationship between the temperature measured during the road testing step and the other parametermeasured during the road testing step using the values of the temperature measured on the tyre test rig and the other parameter measured on the tyre test rig, and using the result to determine the set of temperature-dependent scaling factors.

5. A method of any preceding claim, further comprising the step of measuring values of tread loss of the tyre, or estimating values of tread loss of the tyre based on values of one or more measured parameters associated with the tyre, wherein the step of determining the set of temperature-dependent scaling factors includes comparing the calculated theoretical force or moment values with the measured actual force or moment values or values derived from the measured actual force or moment values, and determining the relationship between the comparison results and the measured or estimated tread loss values.

6. A computer-implemented method of calculating the force or moment acting on the tread surface of a tyre during running, comprising the steps of: calculating the force or moment acting on the tread surface of a tyre during running using a mathematical tyre model; calculating a set of scaling factors based on at least one temperature associated with the tyre; and correcting the calculated force or moment using the set of scaling factors by multiplying the calculated force or moment based on the set of scaling factors.

7. A method of any preceding claim, wherein the force or moment acting on a tyre is calculated using a Pacejka Magic Formula tyre model.

8. A method of claim 6 or 7, wherein the at least one temperature comprises an outer surface temperature of the tyre.

9. A method of claim 8, wherein the outer surface temperature of the tyre is estimated based on at least one of: the roadway speed, the lateral force on the tyre, the longitudinal force on the tyre, the slip angle, brake temperature, and tyre ambient air temperature.

10. A method of any one of claims 6 to 9, wherein the at least one temperature comprises an inner liner temperature of the tyre, and preferably the at least onetemperature comprises at least one of a brake temperature and a tyre ambient air temperature.11 . A method of any one of claims 6 to 10, wherein the set of scaling factors is calculated based on the wear of the tyre.

12. A device configured to carry out the method of any one of claims 6 to 11.

13. A system including the device of claim 12 and at least one sensor configured to measure vehicle body acceleration, body speeds, roadway speed, brake temperature or ambient air temperature.

14. A system according to claim 13, wherein the at least one temperature associated with the tyre is calculated based on the output of the at least one sensor, and preferably the force or moment acting on the tyre is calculated based on the output of the at least one sensor.

15. A method of calculating the force or moment acting on the tread surface of a tyre during running, comprising: determining a set of scaling factors using the method of any one of claims 1 to 5, and calculating the force or moment acting on the tread surface of a tyre during running using the method of any one of claims 6 to 14.

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