GB2565431A

GB2565431A - A controller for a control system of a brake system

Info

Publication number: GB2565431A
Application number: GB1812096.4A
Authority: GB
Inventors: Tam Louis
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-08-11
Filing date: 2018-07-25
Publication date: 2019-02-13
Anticipated expiration: 2038-07-25
Also published as: GB2565431B; GB201712899D0; DE102018212367A1; GB201812096D0

Abstract

A controller for a control system of a brake system is configured to calculate a temperature TB of a brake system of a vehicle by determining whether air flow across the brake system is such that convective heat loss is in a higher heat transfer mode or a lower heat transfer mode; and calculating a temperature of the brake system using the determined heat transfer mode. A signal indicative of the calculated temperature of the brake system is output. Determining whether air flow across the brake system is such that convective heat loss is in a higher heat transfer mode or a lower heat transfer mode may comprise a determination of the turbulence of the air flow using one or both of vehicle speed and an air pressure acting on the vehicle. The heat transfer mode may be looked up using the vehicle speed - fig. 4. A Reynolds number may be calculated for the air flow across the brake system. The Reynolds number may be compared to a threshold to determine the heat transfer mode – fig. 7. A heat transfer number (heat transfer coefficient) may be calculated for convective heat loss using a Reynolds number equation rearranged with the Nusselt number equation S124 fig. 6 / fig. 7. The determined heat transfer mode determines the values of constants used in the calculation S124 fig. 7. The heat transfer coefficient / number is then used to determine convection heat loss from the brake system. The temperature TB of the brake system is determined by calculating a temperature increase due to thermal energy transferred to the brake system deltaT1 149, calculating a temperature decrease due to thermal energy loss from the brake system deltaT2 146, and then subtracting the temperature decrease from the temperature increase and the previous temperature to determine current temperature TB, S180, 151.

Description

A CONTROLLER FOR A CONTROL SYSTEM OF A BRAKE SYSTEM

TECHNICAL FIELD

The present disclosure relates to a controller for a control system of a brake system, Particularly, but not exclusively, the disclosure relates to a controller for a control system of a brake system for a vehicle. Aspects of the invention relate to a controller, a computer readable medium, a method, a brake system and a vehicle.

BACKGROUND

There is a need to monitor a capability of a brake system of a vehicle in order to determine whether the brake system is able to reduce the speed of the vehicle sufficiently when a user of the vehicle applies the brake system.

In conventional vehicles the monitoring of the capability of the brake system involves using a temperature model that calculates a temperature of the brake system. However, such known temperature models highly overestimate how much cooling of the brake system will occur in certain conditions.

It is an aim of the present invention to mitigate a problem of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a controller, a computer readable medium, a brake system, and a vehicle as claimed in the appended claims.

According to an aspect of the invention, there is provided a controller for a control system of a brake system, wherein the controller is configured to calculate a temperature of a brake system of a vehicle, the controller configured to; determine whether air flow across a brake system of a vehicle is in a higher heat transfer mode or a lower heat transfer mode; and calculate a temperature of the brake system using the determined heat transfer mode; and output a signal indicative of the calculated temperature of the brake system.

Advantageously, by the controller determining the heat transfer mode of air flow across the brake system, it provides an improved temperature calculation that does not assume a constant heat transfer mode and, thus, does not overestimate the cooling of the brake system in particular regimes. Consequently, a more accurate brake system temperature model is provided which allows for a better prediction of the behaviour of the brake system.

Optionally, the controller is configured to determine whether air flow across a brake system is in a higher heat transfer mode or a lower heat transfer mode based on a determination of the turbulence of the air flow. Optionally, the controller is configured to determine whether air flow is more turbulent in the higher heat transfer mode and is less turbulent in the lower heat transfer mode. Optionally, the controller is configured to determine the turbulence of the air flow using one or both of: a speed of the vehicle; and an air pressure acting on of the vehicle.

Advantageously, determining the turbulence of the air flow provides a more accurate brake temperature model that avoids overestimation of the cooling of the brake system.

Optionally, the controller compares a Reynolds number for the air flow across the brake system to a threshold representing a transition point between the higher heat transfer mode and the lower heat transfer mode. Optionally, the threshold is a specific Reynolds number. The specific Reynolds number may be selected as a result of experimentation, and may be calibrated for a particular vehicle type or model.

Advantageously, using a Reynolds number for the air flow provides an accurate way of determining whether the air flow is in a higher or lower heat mode by taking into account the speed and size of the braking means and the density and viscosity of the air flow.

Optionally, the controller determines that air flow across a brake system of a vehicle is in the higher heat transfer mode when the Reynolds number is above the threshold. Optionally, the controller determines that air flow across a brake system of a vehicle is in the lower heat transfer mode when the Reynolds number is below the threshold.

Optionally, the controller retrieves the Reynolds number from a storage means before the comparing. Alternatively, the controller calculates the Reynolds number before the comparing.

Optionally the controller may determine the difference between a value of thermal energy loss from the brake system and a value of thermal energy transferred to the brake system. It is to be appreciated that a value of thermal energy may be converted to a temperature.

Optionally, the controller may determine a value of thermal energy loss from the brake system based on the determined heat transfer mode and calculating the temperature of the brake system by subtracting the value of thermal energy loss from a value of thermal energy transferred to the brake system to determine the change in temperature, and then adding the change in temperature to a previous temperature of the brake system.

Optionally, the controller may determine the heat transfer number, when the heat transfer number may be in dependence on the heat transfer mode.

Optionally, the controller may calculates a brake system temperature. The brake system temperature may be the temperature of at least one of: a brake disc, a brake pad, a brake caliper or a brake fluid.

The controller may further comprise controlling a vehicle system in accordance with the signal indicative of the brake system temperature.

Controlling a vehicle system may comprise managing a speed of the vehicle.

Controlling a vehicle system may comprise operating a brake system of the vehicle.

According to another aspect of the invention, there is provided a method for calculating a temperature of a brake system of a vehicle, the method may comprise: determining whether air flow across a brake system of a vehicle is in a higher heat transfer mode or a lower heat transfer mode; and calculating a temperature of the brake system using the determined heat transfer mode; and outputting a signal indicative of the calculated temperature of the brake system.

According to a further aspect of the invention, there is provided a computer readable medium comprising instructions that, when executed, cause a computer to execute a method for calculating a temperature of a brake system of a vehicle, the method may comprise: determining whether air flow across a brake system of a vehicle is in a higher heat transfer mode or a lower heat transfer mode; and calculating a temperature of the brake system using the determined heat transfer mode; and outputting a signal indicative of the calculated temperature of the brake system.

According to a further aspect of the invention, there is provided a vehicle comprising a brake system and the controller.

Optionally, the brake system comprises at least one of: a brake disc; a brake pad, a brake caliper and a brake fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic illustration of a control system of a brake system of a vehicle of Figure 8, in accordance with an embodiment of the invention.

Figure 2 is a schematic illustration of a control system of a brake system of a vehicle of Figure 8, in accordance with an embodiment of the invention.

Figure 3 is a flow chart of a method used by the controller, in accordance with an embodiment of the invention.

Figure 4 is a flow chart of the method used by the controller of Figure 3, showing more detail.

Figure 5 is a flow chart of a method used by the controller, in accordance with an alternate embodiment of the invention of Figure 3.

Figure 6 is a logic flow chart used by the controller, in accordance with the embodiment of the invention of Figure 5.

Figure 7 is a logic flow chart used by the controller, in accordance with the embodiment of the invention of Figure 6.

Figure 8 is a schematic illustration of a vehicle with a control system of a vehicle brake system in accordance with an embodiment of the invention.

Figure 9 is a plot of the temperature profiles of a brake disc for a vehicle cruising at 90kph, comparing data from measured data, a previous model and a proposed model as calculated by the controller in an embodiment of the invention.

Figure 10 is a plot of the temperature profiles of a brake disc for a vehicle cruising at 30kph, comparing data from measured data, a previous model and a proposed model as calculated by the controller in an embodiment of the invention.

DETAILED DESCRIPTION

Figure 1 is a schematic illustration of a control system 350 (of a brake system 200 of a vehicle 400 shown in Figure 8). The control system 350 comprises a controller 300, a storage means 340. The controller 300 comprises a processor 320. The processor 320 is coupled to the storage means 340. The storage means 340 has a computer readable medium 250 storing instructions, that when executed, causes the controller 300 to determine whether the air flow across a brake system 200 is in a higher heat transfer mode or a lower heat transfer mode, the controller calculates a temperature of the brake system 200 using the determined heat transfer mode. The controller 300 outputs a signal 380 indicative of a determined brake system temperature TB 151 available to any other vehicle system or controller as needed, for example to a powertrain controller to derate the engine or implement other measures to manage the speed of the vehicle in accordance with the available brake capacity.

The heat transfer mode may be determined from non-dimensional speed based on the geometric set up of the brake system, this may include the air speed across the brake disc, the measured air temperature, air pressure, the brake disc diameter and looking up the previously stored temperature state,

In an alternative embodiment the air pressure may be an estimation based on the altitude of the vehicle or the altitude of the vehicle and the measured air temperature.

Figure 2 is a schematic illustration of an alternative embodiment of a control system 350 to that shown in figure 1. The embodiment of figure 2 differs from figure 1 with respect that the controller 300 of figure 2 is shown separately coupled to processor 320 of figure 2. It is to be appreciated that the controller 300 of figure 2 is considered to comprise processor 320.

Figure 3 is a flow chart of a method 100 used by the controller 300 for calculating a temperature of a brake system 200 of a vehicle 400 (as shown in Figure 8). The method 100 determines at block S120 whether air flow across a brake system 200 of a vehicle 400 is in a higher heat transfer mode or a lower heat transfer mode and calculates at block S180 a temperature of the brake system 200 using the determined heat transfer mode. At block s190 the controller outputs a generated signal of the determined brake system temperature.

In more detail, at block S120, the method 100 determines whether air flow across a brake system 200 is in a higher heat transfer mode or a lower heat transfer mode based on a determination of the turbulence of the air flow. When the air flow is determined to be more turbulent then the air flow across the brake system 200 is determined to be in the higher heat transfer mode, and when the air flow is less turbulent, in the lower heat transfer mode.

The method 100 determines the turbulence of the air flow using a speed of the vehicle 400 and an air pressure acting on the vehicle 400, but only the speed of the vehicle 400 may be used. Optionally the air pressure may be determined on the altitude of the vehicle 400, or the altitude of the vehicle 400 and air temperature.

Figure 4 is a flow chart illustrating the method 100 of Figure 3 used by the controller 300.

The determining at block S120 of Figure 3 occurs at blocks S122 and S123 of Figure 4. At block S122 the speed of the vehicle 400 is determined.

After the speed is determined, a corresponding heat transfer mode is retrieved, at block S123, from a storage means (illustrated in Figures 1 and 2, 340). The storage means 340 is a lookup table that stores different speeds of vehicle 400 and the corresponding heat transfer mode. As an alternative, the storage means may be any other type of random access memory.

The retrieved heat transfer mode is then used in determining, at block S125, a value of thermal energy loss from the brake system 200. The temperature of the brake system 200, is then calculated at block S180 by subtracting the determined value of thermal energy loss from the brake system 200 from a value of energy transferred to the brake system 200. A signal of the determined brake system temperature is then output s190.

The brake system 200 is a brake disc. The temperature of each brake disc of vehicle 400 is calculated. Alternatively, the brake system may be at least one of a brake disc, a brake pad, a brake caliper or a brake fluid of vehicle 400.

Figure 5 is a flow chart illustrating an embodiment of the method 100 of Figure 3 used by the controller of figures 1 or 2. Figure 5 is an alternative to Figure 4.

The determining at block S120 of Figure 3 is further defined by blocks S122 and S124. At block S122 comparing a Reynolds number for the air flow across the brake system 200 to a threshold representing a transition point between the higher heat transfer mode and the lower heat transfer mode. The threshold is a specific Reynolds number that represents the transition point between the higher heat transfer mode of turbulent air flow and the lower heat transfer mode of laminar air flow.

After the comparing at block S122 the method determines at block S124 that air flow across the brake system 200 of a vehicle 400 is more turbulent and in the higher heat transfer mode when the Reynolds number is above the threshold and determining, at block S124 that air flow across a brake system 200 of a vehicle 400 is less turbulent and in the lower heat transfer mode when the Reynolds number is below the threshold.

The Reynolds number is calculated (block S130 of Figure 7) before the comparing S122.

As an alternative, the Reynolds number may be retrieved from a storage means 340 before the comparing S122. The stored Reynolds numbers are each associated with a different air pressure acting on the vehicle 400. In a slight variation, the stored Reynolds number may also be associated with different speeds of the vehicle 400.

The retrieved heat transfer mode is then used in determining, at block S125, a value of thermal energy loss from the brake system 200. The temperature of the brake system 200, is then calculated at block S180 by subtracting the determined value of thermal energy loss from a value of thermal energy transferred to the brake system 200 to determine the change in temperature, and then adding the change in temperature to a previous temperature system of the brake system 200. A signal of the determined brake system temperature is then output s190.

Figure 6 is a logic flow chart that illustrates the data and processes used to calculate a temperature of a brake system 200 and provides detail on the blocks underlying the embodiment of method 100 of Figure 5 used by the controller of figures 1 or 2. A temperature, Tb, of a brake system 200 is calculated at block S180 by determining a temperature increase, ΔΤι, experienced by the brake system 200 due to heat energy in, 148, to the brake system 200 and a temperature decrease, ΔΤ2, experienced by the brake system 200 due to overall heat loss 145 out of the brake system 200.

In more detail, brake system variables 147 are input into a first thermal energy equation at block S131 to determine heat energy in, 148, to the brake system 200. The first thermal energy equation of block S131 is:

Heat in = Product of the brake system variables 147 (Equation 1)

The brake system variables 147 include the following: brake torque of brake system 200; rotational rate of wheel associated with brake system 200; and heat partition coefficient of the brake system 200.

The heat energy in 148 is input, at block S132, to a first temperature equation with a heat capacity energy coefficient that represents a value of heat energy needed to raise 1 Kg of the brake system 200 by 1 °C and the mass of the brake system 200 to determine an increase in temperature of the brake system 200, ΔΤι, 149.

The first temperature equation of block S132 is:

(Equation 2)

Overall heat loss 145 represents the heat energy lost from the brake system 200 due to cooling.

In calculating the overall heat loss 145, convection heat loss 143 and other heat loss 144 are summed together at block S126:

Overall heat loss = convection heat loss + other heat loss (Equation 3)

The process to arrive at the convection heat loss 143 is now explained. A Reynolds number 140 is input to a heat transfer equation at S124. In doing so, the Reynolds number 140 is rearranged with respect to heat transfer constants to determine a heat transfer number 141 that defines the heat transfer mode of air flow across a brake system 200.

In more detail, at block S124, the Reynolds number equation is rearranged with the Nusselt number equation to give a heat transfer equation that produces a heat transfer number 141.

The heat transfer equation at S124 is: heat transfer number 141 X(Re)Y; (Equation 4) where K is the thermal conductivity of air and D is a characteristic length of the brake system 200, such as a diameter. Re is the Reynolds number 140 and X and Y are constants that are defined by the magnitude of the Reynolds number 140. X and Y may be determined experimentally and may be stored in the storage means 340 (as shown in figures 1 and 2). This is explained in more detail in relation to Figure 7.

At block S125, the determined heat transfer number 141 is used with other variables 142 in a second thermal energy equation to calculate the convection heat loss 143.

The second thermal energy equation of S125 is: convection heat loss = heat transfer number x A x (Tcurrent - Tambient); (Equation 5) where, the heat transfer number is heat transfer number 141 and the other variables 142 are: surface area of the brake system, A; the previous temperature 150 of the brake system, Tcurrent; and the ambient temperature of the air, Tambient.

To calculate the overall heat loss 145, the convection heat loss 143 is summed, S126, with other heat loss amounts 144. The other heat loss amounts at 144 may be due to heat loss through radiation, conduction, and natural convection. However, natural convection is caused by variations in density of the air flow, and is not a result of the behaviour of the air flow as the air flows across the brake system 200, so may be negligible at any significant speed of the brake system, for example, at speeds where the behaviour of the air flow is no longer fully laminar.

The overall heat loss 145 is then input into a second temperature equation at block S127 to calculate the decrease in temperature, ΔΤΖ, 146, of the brake system 200 due to the overall heat loss 145. The second temperature equation is the same equation as the first temperature equation of block S132 is: ΔΤ2 = mass x heat in x energy coefficient. (Equation 6)

At block S180, the increase in temperature 149 is summed with the previous temperature 150 of the brake system. The calculated temperature decrease 146 is subtracted from the sum of the increase in temperature 149 and the previous temperature 150 to give the temperature, TB 151, of the brake system 200.

The previous temperature 150 is, effectively, the temperature of the previous state of the brake system and is fed back into (1) the SUM of S180, and (2) the other variables 142 of the second energy equation at S125, so that the calculated temperature 151 of the brake system 200 is an accurate reflection of the real time temperature of the brake system 200. The outputted temperature 151 may be calculated after a delay in the sum S180 so that the calculated temperature 151 is based on the temperature of the previous state, previous temperature 150, to avoid instantaneous feedback which would be detrimental to the logic flow. Alternatively, the delay may occur in another process of the logic flow that would results in avoidance of instantaneous feedback.

Figure 7 is also a logic flow chart and illustrates, in more detail, the calculation of the Reynolds number 140.

Variables 139 of the brake system 200 and air flow are input into a Reynolds number equation, at block S130. The variables of the brake system and air flow 139 include the following: density of the air; dynamic viscosity of the air; speed of the brake system; and size of the brake system. At S130 the Reynolds number equation is carried out.

The Reynolds number equation is:

(Equation 7) where p = density of the air, v = speed of the brake system 200, D = size of the brake system 200, and μ = dynamic viscosity of the air. The dynamic viscosity and density of the air may be determined from an air pressure estimation of the vehicle associated with the brake system 200.

The calculated Reynolds number 140 is then compared with a threshold at block S122. The threshold represents a transition point between the higher heat transfer mode and the lower heat transfer mode. The threshold is a specific Reynolds number.

After the comparison at block S122, a calculation for the heat transfer number is carried out at block S124 using the calculated Reynolds number 140 and the heat constants, where the heat constants are chosen depending on whether the Reynolds number 140 is above or below the threshold of block S122. This is the same heat transfer equation as described in relation to S124 in Figure 6.

If the Reynolds number 140 is above the threshold, it is determined that the air flow is in a higher heat transfer mode and corresponding heat constants are used in the calculation of block S124.

If it is determined that Reynolds number 140 is below the threshold in the comparison of block S122, it is determined that the air flow is in a lower heat transfer mode and corresponding heat constants are used in the calculation of block S124.

As an example, the threshold may be the specific Reynolds number of 150 000. If the determined Reynolds number 140 is below 150 000 the air flow is in the lower heat transfer mode and in Equation 4 constant X = 0.4, and constant Y = 0.55. If the determined Reynolds number 140 is above 150 000 the air flow is in the lower heat transfer mode and in Equation 4 constant X = 0.7, and constant Y = 0.8. Any or all of the threshold and constant values may be calibrated for a particular vehicle type or model.

As the Reynolds number 140 is calculated on the basis of a linear relationship with the brake air flow speed, it may alternatively be envisaged that the brake air flow speed is compared

with a threshold speed to determine the heat transfer mode. In this alternative the threshold speed may be calculated or retrieved from a lookup table based on the dynamic viscosity and density of the air as determined from an air pressure estimation of the vehicle as discussed above.

Following the calculation at block S124, a heat transfer number is calculated: heat transfer number 141A when the Reynolds number 140 is above the threshold, and heat transfer number 141B if the Reynolds number 140 is below the threshold. The calculated heat transfer number can then be used in a temperature model that calculates the temperature of the brake system. The heat transfer number is in dependence on the heat transfer mode. Since the heat transfer number is different, depending on whether the air flow is in a lower heat transfer mode or a higher heat transfer mode, the temperature model is more accurate and overestimation of cooling of the brake system is avoided.

Figure 8 is a side view of a vehicle 400. The vehicle 400 has a brake system 200 coupled to the control system 350 of Figure 1 or figure 2. The control system 350 may use the determined brake temperature TB when controlling the brake system 200.

Figure 9 compares the temperature profiles of a disc brake during two braking events followed by periods of 90kph cruising of the vehicle. The temperature of the brake disc increases during the braking events and then decreases as the vehicle maintains its speed with no brake application. 90kph may be seen to be within the higher heat transfer mode, and the embodiment of the invention can be seen to provide slightly improved accuracy with respect to the measured data when compared to existing models.

The improvement that the invention provides over existing models is further seen in Figure 10. This shows the vehicle cruising at 30kph after a single braking event has raised the temperature of the brake disc. The temperature of the brake disc decreases as the vehicle maintains its speed with no brake application. At this speed, the vehicle is within the lower heat transfer mode, and as can be seen from the graph the invention provides much improved accuracy with respect to the measured data when compared to the existing model, which do not distinguish between lower and higher heat transfer modes. Hence, the method described above provides an improved estimate of brake temperature in a manner which is not computationally intensive, suitable for inclusion in an embedded physics model in a controller of the vehicle, and is based on a simple parameter of the vehicle.

Whilst the brake system has been described as either a brake pad or brake disc, the brake system may be a combination of a brake pad, a brake disc, a brake caliper and a brake fluid. In addition, the invention may be practised using only one component or any feasible combination, such as brake disc and brake pad, or brake disc and brake caliper, or brake disc and brake fluid. When more than one component is part of the brake system the temperature of each component is calculated individually and interactions between each component (for example, heat transfer by conduction) are modelled to improve accuracy of the temperature model. In one variation the interactions causing heat transfer between components may be used to contribute to the heat in or heat loss values, discussed in relation to Figure 6.

The threshold has been described as is a specific Reynolds number that represents the transition point between the higher heat transfer mode of turbulent air flow and the lower heat transfer mode of laminar air flow. However, as an alternative, the specific Reynolds number may represent a transition point between a higher heat transfer mode of more turbulent air flow and a lower heat transfer mode of less turbulent air flow.

Claims

1. A controller for a control system of a brake system, wherein the controller is configured to calculate a temperature of a brake system of a vehicle, the controller being configured to; determine whether air flow across a brake system of a vehicle is in a higher heat transfer mode or a lower heat transfer mode; and calculate a temperature of the brake system using the determined heat transfer mode; and output a signal indicative of the calculated temperature of the brake system.

2. The controller of claim 1, wherein the controller is configured to determine whether air flow across a brake system is in a higher heat transfer mode or a lower heat transfer mode based on a determination of the turbulence of the air flow.

3. The controller of claim 2, wherein the controller is configured to determine whether the air flow is more turbulent in the higher heat transfer mode and is less turbulent in the lower heat transfer mode.

4. The controller of claim 2 or 3, wherein the controller is configured to determine the turbulence of the air flow using one or both of: a speed of the vehicle; and an air pressure acting on the vehicle.

5. The controller of any preceding claim, wherein the controller is configured to compare a Reynolds number for the air flow across the brake system to a threshold representing a transition point between the higher heat transfer mode and the lower heat transfer mode.

6. The controller of claim 5, wherein the controller is configured to determine that air flow across a brake system of a vehicle is in the higher heat transfer mode when the Reynolds number is above the threshold or the controller determines that air flow across a brake system of a vehicle is in the lower heat transfer mode when the Reynolds number is below the threshold.

7. The controller of claim 6, wherein the controller is configured to retrieve the Reynolds number from a storage means before the comparing.

8. The controller of claim 6, wherein the controller is configured to calculate the Reynolds number before the comparing.

9. The controller of any preceding claim, wherein the controller is configured to determine the difference between a value of thermal energy loss from the brake system and a value of thermal energy transferred to the brake system.

10. The controller of claims 2 to 9, wherein the controller is configured to determine a heat transfer number in dependence on the heat transfer mode.

11. The controller of any preceding claim, wherein the controller is configured to calculate a brake system temperature of at least one of: a brake disc; a brake pad, a brake caliper and of brake fluid.

12. The controller of claim 11 further configured to control a vehicle system in accordance with the signal indicative of the brake system temperature.

13. The controller of claim 12 wherein controlling a vehicle system comprises managing a speed of the vehicle.

14. The controller of claim 12 wherein controlling a vehicle system comprises operating a brake system of the vehicle.

15. A method for calculating a temperature of a brake system of a vehicle, the method comprising: determining whether air flow across a brake system of a vehicle is in a higher heat transfer mode or a lower heat transfer mode; and calculating a temperature of the brake system using the determined heat transfer mode; and outputting a signal indicative of the calculated temperature of the brake system.

16. A computer readable medium comprising instructions that, when executed, cause a computer to execute the method of claim 15.

17. A vehicle comprising a brake system and the controller of any of claims claim 1 to 14.

18. The vehicle of claim 17, wherein the brake system comprises at least one of: a brake disc; a brake pad; a brake caliper; and brake fluid.