Method and system for measuring gradient of road where fuel vehicle is located

Abstract

The method for measuring the slope of the road where the fuel vehicle is located comprises the steps that the volume of urea in a urea box of denitration equipment of the fuel vehicle is obtained; based on the volume of the urea in the urea box, the horizontal liquid level height of the urea when the fuel vehicle is located on the horizontal road is obtained; the distance between a set point located at the bottom of the urea box and the liquid level of the urea in the direction perpendicular to the bottom of the urea box is obtained, and the distance serves as the inclined liquid level height of the urea; the height difference between the inclined liquid level height and the horizontal liquid level height is calculated, and the road gradient is obtained based on the height difference and the volume of urea in the urea box. Also proposed is a system for measuring the grade of a road on which a fuel vehicle is located, comprising a denitration device comprising a urea tank provided with a sensor and a pump, and a processor configured to execute the method according to the invention.

Description

Technical Field

[0001] This invention relates to the field of fuel-powered vehicles. Specifically, it relates to a method and system for measuring the road gradient of a fuel-powered vehicle. Background Technology

[0002] For gasoline-powered vehicles, it is typically necessary to measure the road gradient for driving safety and stability. In response to different road gradients, vehicles need to adaptively adjust their driving parameters to improve power performance and reduce fuel consumption. To measure road gradient, some existing vehicles use mathematical formulas for calculation, but the results are usually inaccurate and lack real-time performance. Other vehicles are equipped with additional sensors, such as accelerometers, to measure road gradient. However, some accelerometers, such as those using analog signals, suffer from low accuracy and reliability in measuring road gradient, for example, the results are sensitive to factors such as temperature and voltage. MEMS-based accelerometers have also emerged, offering high accuracy and reliability, but they are relatively expensive and therefore unsuitable for widespread use in measuring road gradient in gasoline-powered vehicles.

[0003] Therefore, there is a need for a method and system that is low-cost, accurate, and reliable for measuring the road gradient of fuel-powered vehicles. Summary of the Invention

[0004] To address the above problems, this invention proposes a method and system for measuring the road gradient of a fuel-powered vehicle.

[0005] The method for measuring the road gradient of a fuel-powered vehicle according to the present invention includes:

[0006] Obtain the volume of urea in the urea tank of the denitrification equipment in fuel-powered vehicles;

[0007] The horizontal liquid level of urea is obtained based on the volume of urea in the urea tank when the fuel vehicle is on a level road.

[0008] Obtain the distance from a set point located at the bottom of the urea tank to the urea surface in a direction perpendicular to the bottom of the urea tank, and use this distance as the tilted urea surface height; and

[0009] Calculate the height difference between the inclined liquid surface and the horizontal liquid surface, and obtain the road slope based on this height difference and the volume of urea in the urea tank.

[0010] The volume of urea in the urea tank is calculated by subtracting the volume of urea that has been removed from the urea tank from the total volume when the urea tank is full of urea.

[0011] Optionally, the height difference between the inclined liquid surface height and the horizontal liquid surface height is calculated only when the range of change of the inclined liquid surface height within a set time period is less than a set threshold range, and the road slope is obtained based on the height difference and the volume of urea in the urea tank.

[0012] Alternatively or additionally, the height of the urea inclined liquid level is obtained multiple times consecutively, and the height difference is calculated as the difference between the average of the heights of the urea inclined liquid level obtained multiple times consecutively and the height of the horizontal liquid level.

[0013] The method according to the invention may further include pre-establishing and storing a mapping relationship between the road slope where the fuel vehicle is located and the volume and height difference of urea in the urea tank, and obtaining the road slope by retrieving the mapping relationship after obtaining the volume and height difference of urea in the urea tank.

[0014] The system for measuring the road gradient of a fuel-powered vehicle according to the present invention includes:

[0015] A denitrification device including a urea tank, wherein the urea tank includes a sensor and a pump mounted thereto, the sensor being configured to measure the distance from a setpoint located at the bottom of the urea tank to the surface of the urea in a direction perpendicular to the bottom of the urea tank, and the pump being configured to draw urea from the urea tank; and

[0016] The processor, which communicates with the sensors and pump, is configured to:

[0017] Obtain the volume of urea in the urea tank;

[0018] The horizontal liquid level of urea is obtained based on the volume of urea in the urea tank when the fuel vehicle is on a level road.

[0019] The distance acquired by the sensor is used as the height of the tilted urea liquid surface; and

[0020] Calculate the height difference between the inclined liquid surface and the horizontal liquid surface, and obtain the road slope based on this height difference and the volume of urea in the urea tank.

[0021] Overall, the processor can acquire the status parameters of the sensors and pumps and is configured to execute the method according to the invention.

[0022] The system for measuring the road gradient of a fuel vehicle according to the present invention may further include a memory storing a pre-established mapping relationship between the road gradient of the fuel vehicle and the volume and height difference of urea in the urea tank, and the processor is further configured to obtain the road gradient by retrieving the mapping relationship after obtaining the volume and height difference of urea in the urea tank.

[0023] The present invention also proposes a computer program product comprising computer instructions that, when executed by a processor, implement the method according to the present invention. Attached Figure Description

[0024] The method and system for measuring the road gradient of a fuel-powered vehicle according to the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0025] Figure 1A A schematic cross-sectional view of the urea tank of the denitrification equipment is shown when the fuel-powered vehicle is on a level road;

[0026] Figure 1B A schematic cross-sectional view of the urea tank of the denitrification equipment is shown when a fuel-powered vehicle is on an inclined road;

[0027] Figure 2 A flowchart illustrating a method for measuring road gradient for fuel-powered vehicles according to the present invention; and

[0028] Figure 3 A schematic block diagram of a system for measuring road gradient for fuel-powered vehicles according to the present invention is shown. Detailed Implementation

[0029] Today, emission standards for gasoline-powered vehicles are becoming increasingly stringent. Therefore, existing gasoline-powered vehicles are typically equipped with denitrification (DENOX) systems to reduce nitrogen oxide emissions in exhaust gases. Denitrification systems include a urea tank containing DEF (diesel exhaust fluid, also known as automotive urea). The urea in the tank is pumped to the vehicle's exhaust system to reduce nitrogen oxides in the exhaust. Sensors, such as ultrasonic sensors, are usually installed at the bottom of the urea tank to measure the level of remaining urea, and the driver can view the remaining urea level in real time on the dashboard. A pump is also usually installed in the urea tank, for example at the bottom, to draw urea from the tank to other external devices.

[0030] Figure 1A A schematic cross-sectional view of the urea tank of the denitrification system is shown when the fuel-powered vehicle is on a level road. Figure 1B A schematic cross-sectional view of the urea tank of the denitrification system is shown when a fuel-powered vehicle is on an inclined road. Among them, Figure 1A and Figure 1B The diagram schematically shows a sensor 110, such as an ultrasonic sensor, installed at a set point at the bottom of the urea tank 100. The sensor 110 is configured to measure the distance from the set point to the surface of the urea liquid in a direction perpendicular to the bottom of the urea tank 100. Figure 1A and Figure 1BThe diagram also schematically shows a pump 120 installed in the urea tank 100, for example located at the center of the bottom of the urea tank 100, which is configured to draw urea from the urea tank 100 to pump the urea to react with the vehicle's exhaust gas to reduce the emission of nitrogen oxides in the exhaust gas.

[0031] It should be noted that Figure 1A and Figure 1B The arrangement of sensor 110 and pump 120 in urea tank 100 is only simplified and illustrated, but their arrangement in urea tank 100 is not limited to this. Since existing denitrification equipment urea tanks are equipped with such sensors and pumps, a detailed description of their specific construction is omitted in this document.

[0032] It should also be noted that Figure 1A and Figure 1B The sensor 110 is shown to have a certain thickness, i.e., it protrudes upward from the bottom of the urea tank 100. However, the distance measured by the sensor 110 can be considered or converted to the distance from a set point at the bottom of the urea tank 100 (e.g., the centroid of the sensor projected onto the bottom of the urea tank 100) to the liquid surface of the urea in a direction perpendicular to the bottom of the urea tank 100.

[0033] During the process of the vehicle going uphill or downhill, the urea level in the urea tank 100 tilts, and the height of the remaining urea level measured by the sensor 110 may not accurately reflect the amount of remaining urea. Therefore, the information on the amount of remaining urea obtained by the driver from the instrument panel may be inaccurate.

[0034] This invention proposes a method for measuring the road slope of a fuel-powered vehicle. It utilizes the existing denitrification equipment in the fuel-powered vehicle, which not only achieves low-cost, high-accuracy and high-reliability measurement of road slope, but also avoids misjudgment of the amount of residual urea in the urea tank of the denitrification equipment.

[0035] See Figure 2 The method according to the present invention generally includes the following steps:

[0036] S101: Obtain the volume of urea in the urea tank 100 of the denitrification equipment of a fuel-powered vehicle;

[0037] S201: Based on the volume of urea in the urea tank 100, obtain the horizontal liquid level height H1 of urea when the fuel vehicle is driving on a level road;

[0038] S301: Obtain the distance from the urea liquid surface measured perpendicularly to the bottom of the urea tank 100 at a set point located at the bottom of the urea tank 100, and use this distance as the urea tilting liquid surface height H2; and

[0039] S401: Calculate the height difference between the inclined liquid surface height H2 and the horizontal liquid surface height H1, and obtain the road slope based on this height difference and the volume of urea in the urea tank 100.

[0040] The volume of urea obtained in step S101 is the volume of the remaining urea in the urea tank 100 of the denitrification equipment. It can be obtained by subtracting the volume of urea consumed during vehicle operation, i.e. the volume of urea that has been extracted from the urea tank 100, from the initial urea volume in the urea tank 100 (i.e., the total volume when the urea tank 100 is filled with urea).

[0041] As mentioned earlier, the urea tank 100 of the denitrification equipment is typically equipped with a pump 120 for drawing urea from the urea tank 100, for example... Figure 1A and Figure 1B The pump 120 is installed at the center of the bottom of the urea tank 100. Therefore, the volume of urea drawn by the pump 120 can be detected as the volume of urea consumed. That is, the volume of urea obtained in step S101 can be calculated by subtracting the volume of urea drawn by the pump 120 used to draw urea from the urea tank 100 from the total volume when the urea tank 100 is filled with urea.

[0042] Since the structure and dimensions of the urea tank 100 are known in advance, after obtaining the volume of urea in the urea tank 100 of the denitrification equipment of the fuel vehicle in step S101, the horizontal liquid level height H1 of urea when the fuel vehicle is driving on a level road can be obtained in step S201 based on the volume of urea in the urea tank 100. Figure 1A As shown. The height H1 of the horizontal liquid level is the distance from the horizontal liquid level to the bottom of the urea tank 100 in the direction perpendicular to the bottom of the urea tank 100 (vertical direction).

[0043] The horizontal urea level height H1 obtained in step S201 assumes the fuel vehicle is on a level road (the urea level is horizontal and stationary). However, in actual driving, the fuel vehicle is not always on a level road, but may be driving on a slope. The method of the present invention includes step S301 to obtain the inclined urea level height in the urea tank 100 when the fuel vehicle is driving on a slope: obtaining the distance from the urea level measured from a set point located at the bottom of the urea tank 100 in a direction perpendicular to the bottom of the urea tank 100, and using this distance as the inclined urea level height H2, as shown. Figure 1BAs shown. The set point at the bottom of the urea tank 100 can be the position of the sensor 110 at the bottom of the urea tank 100, such as the centroid of the projection of the sensor 110 on the bottom of the urea tank 100 or the position where the sensor 110 emits an ultrasonic signal. The height H2 of the inclined liquid surface of the urea can be the distance from the liquid surface of the urea measured by the sensor 110, for example, an ultrasonic sensor, perpendicular to the bottom of the urea tank 100.

[0044] During vehicle operation, the urea level in the urea tank 100 may fluctuate due to road conditions or driver operation, thus the urea tilt level height H2 obtained by sensor 110 may be unstable. To eliminate this instability, the method according to the present invention may include filtering the measured urea tilt level height.

[0045] Specifically, step S301 may include sub-step S302, which involves calculating the height difference between the inclined liquid level and the horizontal liquid level only when the variation range of the urea inclined liquid level height H2 obtained within a set time period is less than a set threshold range, and obtaining the road slope based on this height difference and the volume of urea in the urea tank. In other words, the urea inclined liquid level height H2 obtained in step S301 is filtered to remove unstable driving situations. These unstable driving situations include, for example, vehicles driving on uneven roads, where the road itself may be horizontal or inclined, but its uneven surface causes instability in the urea inclined liquid level height H2 obtained by sensor 110, or sudden changes in vehicle speed caused by driver operation, etc. The aforementioned set time period and the set threshold range for the variation of the inclined liquid level height H2 can be adaptively adjusted. The filtering operation of this invention can be Gaussian filtering, but other filtering methods can also be used, as long as they can filter out abnormal fluctuations in the urea tilted liquid level height H2.

[0046] Alternatively or additionally, step S301 may include sub-step S303, which involves continuously acquiring the urea tilted liquid level height H2 using sensor 110, and calculating the aforementioned height difference as the difference between the average of the continuously acquired tilted liquid level heights and the aforementioned horizontal liquid level height. During actual vehicle operation, even without uneven road surfaces or sudden speed changes, the urea in the urea tank 100 may not always be stationary, but may fluctuate slightly. Therefore, using the average of the continuously acquired tilted liquid level height H2 to calculate the height difference can minimize the impact of such slight fluctuations in urea on the measurement results. The number of times the tilted liquid level height is continuously acquired to calculate the average tilted liquid level height H2 can be adaptively adjusted.

[0047] Figure 2 Neutron steps S302 and S303 are shown in dashed boxes, indicating that they are optional steps in the method according to the invention. However, steps S302 and S303 can improve the accuracy of the results obtained by the method of the invention.

[0048] Preferably, sub-steps S302 and S303 can be combined. That is, sub-step S302 first filters the urea tilted liquid level height H2 to filter out unstable driving conditions. Then, sub-step S303 calculates the height difference using the average of multiple consecutively acquired urea tilted liquid level heights to minimize the impact of small fluctuations in urea levels on the measurement results. This method ensures high accuracy in obtaining the urea tilted liquid level height.

[0049] The applicant discovered a correlation between the road slope where the fuel vehicle is located and the volume of urea in the urea tank, as well as the height difference between the inclined and horizontal urea levels in the urea tank. Therefore, according to the method of the present invention, after obtaining the horizontal urea level in step S201 and the inclined urea level in step S301, or optionally in sub-steps S302 and S303, the method may further include step S401: calculating the height difference between the inclined and horizontal urea levels, and obtaining the road slope based on this height difference and the volume of urea in the urea tank.

[0050] Since there is a correlation between the road slope where the fuel vehicle is located and the volume of urea in the urea tank, as well as the height difference between the inclined and horizontal urea levels in the urea tank, a mapping relationship between the road slope where the fuel vehicle is located and the volume of urea in the urea tank, as well as the height difference between the inclined and horizontal urea levels in the urea tank, can be pre-established and stored. Therefore, after obtaining the volume of urea in the urea tank and the height difference between the inclined and horizontal urea levels in the urea tank, the road slope where the fuel vehicle is located can be quickly obtained by retrieving this mapping relationship.

[0051] It should be noted that the road slope of the fuel vehicle obtained by the method according to the present invention includes not only the magnitude (degrees) of the slope, but also the direction of the slope (whether it is uphill or downhill for the vehicle). For example, Figure 1BThe diagram illustrates a vehicle traveling downhill. In this case, the height H2 of the inclined liquid surface, measured by sensor 110, is greater than the height H1 of the horizontal liquid surface; therefore, the calculated height difference is positive. In other words, using the method according to the present invention, a positive calculated height difference indicates the vehicle is traveling downhill. Although not shown in the diagram, it is easy to understand that a negative calculated height difference indicates the vehicle is traveling uphill, and a zero calculated height difference indicates the vehicle is traveling on a level road. Furthermore, the magnitude of the road gradient (degrees) is positively correlated with the absolute value of the height difference. That is, given the known volume of urea in the urea tank 100, a larger absolute value of the height difference indicates a larger road gradient (degrees), and vice versa.

[0052] The present invention also proposes a system for measuring the road gradient where a fuel-powered vehicle is located. Figure 3 A schematic block diagram of a system 10 according to the present invention is shown. The system 10 includes:

[0053] A denitrification device including a urea tank 100, wherein the urea tank 100 includes a sensor 110 and a pump 120 mounted thereto, the sensor 110 being configured to measure the distance from a set point located at the bottom of the urea tank 100 to the surface of the urea in a direction perpendicular to the bottom of the urea tank 100, and the pump 120 being configured to draw urea from the urea tank 100; and

[0054] Processor 200, which is communicatively connected to sensor 110 and pump 120, is configured to:

[0055] Obtain the volume of urea in urea tank 100;

[0056] The horizontal liquid level of urea is obtained when the fuel vehicle is on a level road, based on the volume of urea in the urea tank 100.

[0057] The distance acquired by sensor 110 is used as the height of the tilted urea liquid surface; and

[0058] Calculate the height difference between the inclined liquid surface height and the horizontal liquid surface height, and obtain the road slope based on the height difference and the volume of urea in the urea tank 100.

[0059] The sensor 110 is, for example, an ultrasonic sensor, and it measures the distance from the point where it emits an ultrasonic signal at the bottom of the urea tank 100 (i.e., the aforementioned set point) to the surface of the urea in a direction perpendicular to the bottom of the urea tank 100. When the vehicle is on a level road, this distance is... Figure 1A The height H1 shown is [height], while the distance is [distance] when the vehicle is on an inclined road. Figure 1B The height H2 is shown.

[0060] Overall, the processor 200 can acquire the status parameters of the sensor 110 and the pump 120 and is configured to execute the method according to the invention.

[0061] Specifically, the processor 200 can be configured to calculate the volume of urea in the urea tank 100 by subtracting the volume of urea drawn by the pump 120 used to draw urea from the urea tank 100 from the total volume when the urea tank 100 is filled with urea.

[0062] The processor 200 can be further configured to compare the range of change of the inclined liquid surface height H2 obtained within a set time period with a set threshold range, and only calculate the height difference between the inclined liquid surface height H2 and the horizontal liquid surface height H1 when the range of change of the inclined liquid surface height H2 obtained within the set time period is less than the set threshold range, and obtain the road slope based on the height difference and the volume of urea in the urea tank 100.

[0063] Alternatively or additionally, the processor 200 may be further configured to acquire the tilted liquid level height H2 of urea multiple times consecutively, and calculate the aforementioned height difference as the difference between the average value of the tilted liquid level height H2 of urea acquired multiple times consecutively and the aforementioned horizontal liquid level height.

[0064] The system 10 according to the invention may further include a memory 300 storing a pre-established mapping relationship between the road slope where the fuel vehicle is located, the volume of urea in the urea tank, and the height difference between the inclined liquid level and the horizontal liquid level. The processor 200 may be further configured to obtain the road slope by retrieving this mapping relationship after acquiring the volume of urea in the urea tank and the height difference. The road slope obtained by the processor 200 through this mapping relationship includes the magnitude (degrees) and direction of the slope.

[0065] The processor 200 can be further configured to communicate with the instrument panel located in the cab and display the acquired road gradient on the instrument panel in real time. This allows the driver to obtain accurate road gradient information in real time and thus adjust driving parameters accordingly to improve power performance and reduce fuel consumption.

[0066] Alternatively, the processor 200 can be configured to communicate with the vehicle's driver assistance system and control the driver assistance system to adjust its operating status based on real-time road gradient information, so as to automatically adjust driving parameters in response to changes in road gradient.

[0067] In summary, the system 10 according to the invention can perform the method according to the invention. Since the hardware utilized by the method and system according to the invention is the sensor and pump of the urea tank of the existing denitrification equipment in existing fuel vehicles, the method and system according to the invention achieves low-cost, high-accuracy and high-reliability measurement of the road slope where the fuel vehicle is located without requiring hardware modification to the fuel vehicle.

[0068] It should also be noted that existing fuel-powered vehicles are typically equipped with accelerometers to measure the road gradient. However, the method and system of this invention employ a completely different principle than that of an accelerometer to measure road gradient. The road gradient measured by the method of this invention can be compared with that measured by an accelerometer, and the reliability of the road gradient measurement results can be increased based on the comparison results. For example, if there is a significant error between the road gradient measured by the method of this invention and that measured by an accelerometer, there may be a malfunction in the accelerometer or components of the urea tank, such as sensors and pumps, which can alert the driver or maintenance personnel to check the relevant components.

[0069] The present invention also proposes a computer program product comprising computer instructions that, when executed by a processor, implement the method according to the invention. The computer instructions may be stored in the aforementioned memory and may be executed by the aforementioned processor.

[0070] The present invention also proposes a machine-readable storage medium, which may be the aforementioned memory, storing computer instructions that, when executed by a processor, implement the method according to the present invention.

[0071] The foregoing description, with reference to the accompanying drawings, details feasible but non-limiting embodiments of the method and system for measuring the road gradient of a fuel-powered vehicle according to the present invention. Modifications and additions to the technology and structure, as well as recombinations of features in the various embodiments, should be considered within the scope of the invention by those skilled in the art without departing from the scope and spirit of this disclosure as set forth in the following claims. Therefore, such modifications and additions conceivable under the teachings of this invention should be considered part of this disclosure. The scope of this disclosure is defined by the following appended claims and includes equivalent technologies known at the filing date of this disclosure and equivalent technologies not yet foreseen.

Claims

1. Methods for measuring the road gradient where a fuel-powered vehicle is located, including: Obtain the volume of urea in the urea tank of the denitrification equipment of the fuel vehicle; The horizontal liquid level of urea is obtained based on the volume of urea in the urea tank when the fuel vehicle is on a level road. Obtain the distance from a set point located at the bottom of the urea tank to the surface of the urea in a direction perpendicular to the bottom of the urea tank, and use the distance as the height of the tilted urea surface; as well as Calculate the height difference between the inclined liquid level and the horizontal liquid level, and obtain the road slope based on the height difference and the volume of urea in the urea tank.

2. The method according to claim 1, wherein, The volume of urea in the urea tank is calculated by subtracting the volume of urea that has been withdrawn from the urea tank from the total volume of the urea tank when it is full of urea.

3. The method according to claim 1, wherein, The height difference between the inclined liquid surface height and the horizontal liquid surface height is calculated only when the change range of the inclined liquid surface height within a set time period is less than a set threshold range, and the road slope is obtained based on the height difference and the volume of urea in the urea tank.

4. The method of claim 3, further comprising: The height of the urea tilted liquid surface is obtained multiple times consecutively, and the height difference is calculated as the difference between the average value of the height of the urea tilted liquid surface obtained multiple times consecutively and the height of the horizontal liquid surface.

5. The method according to any one of claims 1 to 4, further comprising: A mapping relationship between the road slope where the fuel vehicle is located, the volume of urea in the urea tank, and the height difference is established and stored in advance. After obtaining the volume of urea in the urea tank and the height difference, the road slope is obtained by retrieving the mapping relationship.

6. A system (10) for measuring the road gradient where a fuel-powered vehicle is located, comprising: A denitrification device including a urea tank (100), wherein the urea tank (100) includes a sensor (110) and a pump (120) mounted thereto, the sensor (110) being configured to measure the distance from a set point located at the bottom of the urea tank (100) to the liquid surface of the urea in a direction perpendicular to the bottom of the urea tank (100), and the pump (120) being configured to draw urea from the urea tank (100); as well as A processor (200), which is communicatively connected to the sensor (110) and the pump (120) and is configured to: Obtain the volume of urea in the urea tank (100); The horizontal liquid level of the urea is obtained based on the volume of urea in the urea tank (100) when the fuel vehicle is on a level road; The distance acquired by the sensor (110) is used as the height of the tilted liquid surface of the urea; and Calculate the height difference between the inclined liquid level and the horizontal liquid level, and obtain the road slope based on the height difference and the volume of urea in the urea tank (100).

7. The system (10) according to claim 6, wherein the processor (200) is further configured to compare the range of change of the inclined liquid level height obtained within a set time period with a set threshold range, and calculate the height difference between the inclined liquid level height and the horizontal liquid level height only when the range of change of the inclined liquid level height obtained within the set time period is less than the set threshold range, and obtain the road slope based on the height difference and the volume of urea in the urea tank (100).

8. The system (10) according to claim 7, wherein the processor (200) is further configured to acquire the tilted liquid level height of the urea multiple times consecutively, and calculate the height difference as the difference between the average value of the tilted liquid level height of the urea acquired multiple times consecutively and the horizontal liquid level height.

9. The system (10) according to any one of claims 6 to 8, further comprising a memory (300) storing a pre-established mapping relationship between the road slope where the fuel vehicle is located and the volume of urea in the urea tank and the height difference, and the processor (200) being further configured to obtain the road slope by retrieving the mapping relationship after obtaining the volume of urea in the urea tank and the height difference.

10. A computer program product comprising computer instructions that, when executed by a processor, implement the method according to any one of claims 1 to 4.

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