Automobile speed display method and automobile speed display device

Abstract

The present application discloses a vehicle speed display method and a vehicle speed display device, which relate to the technical field of vehicle-mounted equipment, including setting a filter coefficient according to the cruise control accuracy, wherein the cruise control accuracy is inversely proportional to the filter coefficient; filtering the filter coefficient, the displayed speed at the previous moment, and the unfiltered converted speed at the current moment to obtain the filtered converted speed at the current moment; rounding the filtered converted speed at the current moment to obtain the displayed speed at the current moment, and displaying it. The present application can set the filter coefficient according to the cruise control accuracy, calculate the converted speed after filtering out fluctuations according to the filter coefficient, the current displayed speed, and the current converted speed, and obtain the displayed speed by rounding out the converted speed after filtering out fluctuations. When the actual speed exceeds a certain threshold, the current converted speed will be used to cause the current displayed speed to change, and the actual speed change can be captured in time to improve the display accuracy and stability.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle-mounted equipment, and in particular to a vehicle speed display method and a vehicle speed display device. Background Art

[0002] During vehicle driving, speed display and control are very important, especially for autonomous vehicles, which are strongly related to speed. Most control functions are based on speed as a condition for opening and exiting functions. At the same time, the stability and reliability of speed determine the safety performance of the vehicle. With the demand for intelligent driving functional safety, the functional safety method is used to derive the safety requirement that the vehicle speed must reach asild (automotive safety integration level, usually divided into four levels from a to d, with a lowest level and a highest level). At present, the vehicle speed is generally calculated by ESC (Electronic Stability Controller, the abbreviation of the electronic stability control system of the vehicle body). The conventional calculation method uses the wheel speed sensor pulses of the two front wheels. When turning or one wheel slips, the vehicle speed value will deviate. If it is necessary to further meet the level requirements of asild, an intelligent wheel speed sensor is required, and the ESC hardware and software need to be redesigned and developed for the safety level (currently, the vehicle speed measured by ESC can only reach asilb).

[0003] The speed displayed on the car instrument is generally derived from the actual speed calculated by the ESC based on the wheel speed sensor. The displayed speed is converted based on the actual speed on the bus based on certain conversion rules. However, although the actual speed calculated by the ESC is highly accurate, the instrument only needs to display an integer value when displaying the speed. Therefore, in general, when the instrument displays the speed, the converted speed needs to be rounded off to obtain the displayed speed for display on the instrument. The specific rounding method is rounding down, rounding up, or rounding up.

[0004] The displayed speed after rounding can also ensure that the speed value changes within 1kph remain stable, but no matter which rounding method is used, when it fluctuates near the rounding critical value, it will cause a rapid jump in the speed. Taking the speed rounded down as an example, when the instrument converted speed (in kph) is 59.7, 59.8, 59.9, 60.0, and 59.9 over time, the corresponding displayed speed (in kph) is 59, 59, 59, 60, and 59 over time. From the above example, it can be seen that when the converted value fluctuates between 59.9 and 60.0, the displayed speed will jump rapidly between 59 and 60. When the vehicle is driven manually, the impact will not be particularly obvious, but when the automatic driving mode is turned on, such as when the vehicle is controlled by the cruise function, the speed is prone to rapid jumps, causing discomfort to the driver.

[0005] In response to the above technical problems, the prior art proposes a vehicle speed display method and a vehicle speed display device, the vehicle speed display method comprising: obtaining a first bus vehicle speed signal value at a first time and a second bus vehicle speed signal value at a second time, wherein the second time is earlier than the first time and is adjacent to the first time; in response to the vehicle speed change value between the first bus vehicle speed signal value and the second bus vehicle speed signal value being greater than a predetermined change threshold, displaying the first bus vehicle speed signal value; in response to the vehicle speed change value being less than or equal to the predetermined change threshold, increasing the time accumulation variable; and in response to the time accumulation variable being greater than the time accumulation threshold, displaying the first bus vehicle speed signal value. In this way, the problem of too fast speed jump displayed by the vehicle display terminal or the vehicle instrument can be solved, and the user's experience of the display function of the vehicle-mounted device can be improved.

[0006] However, there are still some problems with the above technical solution. For example, when the collection cycle is 1s, the predetermined change threshold is 0.5kph, and the time accumulation threshold is 5s, when the first bus speed signal value and the second bus speed signal value change with the deviation value of the comparison limit as shown in Table 1 below, the difference between the two bus values ​​collected in each collection cycle does not exceed the predetermined change threshold. As the accumulated variable increases over time, after accumulating five collection cycles, that is, 5s, the displayed value is directly updated from 59 in the first 4s to 61 in the 5th second. The speed display jumps and shows nonlinear changes.

[0007] Second bus value First bus value Difference Display value 59.9 - - 59 59.9 60.3 0.4 Display value not updated: 59 60.3 60.7 0.4 Display value not updated: 59 60.7 61.1 0.4 Display value not updated: 59 61.1 61.5 0.4 Display value updated: 61

[0008] Table 1 Example of changes in the displayed value of the vehicle speed from 0s to 5s Summary of the invention

[0009] In view of the defects existing in the prior art, the purpose of the present application is to provide a vehicle speed display method and a vehicle speed display device, which can convert the current vehicle speed only when the actual vehicle speed exceeds a certain threshold, causing the current displayed vehicle speed to change, and can capture the actual vehicle speed change in time to improve the display accuracy.

[0010] In order to achieve the above objectives, the technical solutions adopted are:

[0011] A method for displaying vehicle speed, comprising:

[0012] Setting a filter coefficient according to cruise control accuracy, wherein the cruise control accuracy is proportional to the filter coefficient;

[0013] Perform filtering processing based on the filter coefficient, the displayed vehicle speed of the previous sampling period, and the unfiltered converted vehicle speed of the current sampling period to obtain the filtered converted vehicle speed of the current sampling period;

[0014] The filtered converted vehicle speed of the current sampling period is rounded to obtain the displayed vehicle speed of the current sampling period, and then displayed.

[0015] In some embodiments, the filtered converted vehicle speed is calculated using the following filtering formula:

[0016]

[0017] in,

[0018] n is used to indicate the acquisition period for converting vehicle speed;

[0019] Used to indicate the filtered converted vehicle speed of the current acquisition cycle;

[0020] α is used to represent the filter coefficient;

[0021] X(n) is used to represent the unfiltered converted vehicle speed of the current acquisition period;

[0022] Y(n-1) is used to represent the displayed vehicle speed in the previous acquisition cycle.

[0023] In some embodiments, the setting of the filter coefficient according to the cruise control accuracy further includes:

[0024] Setting a vehicle speed hysteresis zone according to the cruise control accuracy, wherein the cruise control accuracy is proportional to the vehicle speed hysteresis zone;

[0025] Add 1 to the speed hysteresis zone to get the speed fluctuation range;

[0026] The lower limit and upper limit of the vehicle speed fluctuation range are respectively substituted into the filtering formula, and the value of the filtering coefficient is adjusted until the difference between the filtered converted vehicle speed of the current acquisition cycle and the displayed vehicle speed of the previous acquisition cycle is no more than 1, thereby obtaining the set value of the filtering coefficient.

[0027] In some embodiments, the filter coefficient has a value range of (0, 1].

[0028] In some embodiments, the rounding process is performed by rounding up, rounding down, or rounding off.

[0029] A vehicle speed display device, comprising:

[0030] A collection and setting module, which is used to set a filter coefficient according to a cruise control accuracy, wherein the cruise control accuracy is proportional to the filter coefficient;

[0031] The conversion and rounding module is used to perform filtering processing on the filter coefficient, the displayed vehicle speed at the previous moment, and the unfiltered converted vehicle speed at the current moment to obtain the filtered converted vehicle speed at the current moment; it is also used to round the filtered converted vehicle speed at the current moment to obtain the displayed vehicle speed at the current moment, and display it.

[0032] In some embodiments, the filtered converted vehicle speed is calculated using the following filtering formula:

[0033]

[0034] in,

[0035] n is used to indicate the acquisition period for converting vehicle speed;

[0036] Used to indicate the filtered converted vehicle speed of the current acquisition cycle;

[0037] α is used to represent the filter coefficient;

[0038] X(n) is used to represent the unfiltered converted vehicle speed of the current acquisition period;

[0039] Y(n-1) is used to represent the displayed vehicle speed in the previous acquisition cycle.

[0040] In some embodiments, the acquisition setting module is also used to set a vehicle speed hysteresis zone according to the cruise control accuracy, and the cruise control accuracy is proportional to the vehicle speed hysteresis zone; the vehicle speed hysteresis zone is added by 1 to obtain a vehicle speed fluctuation range; the lower limit value and the upper limit value of the vehicle speed fluctuation range are respectively substituted into the filtering formula, and the value of the filtering coefficient is adjusted until the difference between the filtered converted vehicle speed of the current acquisition cycle and the displayed vehicle speed of the previous acquisition cycle is no more than 1, thereby obtaining a set value of the filtering coefficient.

[0041] In some embodiments, the filter coefficient has a value range of (0, 1].

[0042] In some embodiments, the rounding process is performed by rounding up, rounding down, or rounding off.

[0043] The beneficial effects of the technical solution provided by this application include:

[0044] According to the actual vehicle speed in the CAN bus signal received in this acquisition cycle, the unfiltered converted vehicle speed of this acquisition cycle is converted, and the filter coefficient is used as the weight of the unfiltered converted vehicle speed of this acquisition cycle, and the complement of the filter coefficient is used as the weight of the displayed vehicle speed of the previous acquisition cycle to calculate the converted vehicle speed after filtering in the current cycle, and the displayed vehicle speed of this acquisition cycle is obtained by rounding the converted vehicle speed. Compared with the existing solution, which takes two CAN values ​​for comparison or filtering, this patent is more stable for the speed display under precise control.

[0045] The filter coefficient can adjust relevant parameters according to different steady-state control accuracy requirements. When the steady-state control accuracy of the cruise function is poor, the value of the filter coefficient can be relatively small. It is suitable for all project development, with more flexible application and wider scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The figure is a flow chart of a method for displaying vehicle speed in an embodiment of the present invention.

[0047] Figure 2 Schematic diagram of the functional modules of the vehicle speed display device in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0049] like Figure 1 As shown, an embodiment of the present invention provides a method for displaying the speed of an automobile, including setting a filter coefficient according to the accuracy of cruise control, the cruise control accuracy being proportional to the filter coefficient; filtering the filter coefficient, the displayed speed at the previous moment, and the unfiltered converted speed at the current moment to obtain the filtered converted speed at the current moment; rounding the filtered converted speed at the current moment to obtain the displayed speed at the current moment, and displaying it. The present invention can set the filter coefficient in combination with the accuracy of cruise control, calculate the converted speed after filtering out fluctuations in combination with the filter coefficient, the current displayed speed, and the current converted speed, and round the converted speed after filtering out fluctuations to obtain the displayed speed, which can only pass through the current converted speed when the actual speed exceeds a certain threshold, resulting in a change in the current displayed speed, and can timely capture the actual speed change, thereby improving display accuracy and stability.

[0050] In a specific embodiment, the above-mentioned vehicle speed display method includes:

[0051] Step S1, setting a filter coefficient according to cruise control accuracy, wherein the cruise control accuracy is proportional to the filter coefficient.

[0052] Step S2, filtering is performed based on the filter coefficient, the displayed vehicle speed at the previous moment, and the unfiltered converted vehicle speed at the current moment to obtain the filtered converted vehicle speed at the current moment.

[0053] Step S3: rounding the filtered converted vehicle speed at the current moment to obtain the displayed vehicle speed at the current moment, and displaying it.

[0054] In this embodiment, the unfiltered converted speed of this acquisition cycle is obtained according to the actual speed in the CAN bus signal received in this acquisition cycle, and the converted speed after filtering out fluctuations is calculated by combining the filter coefficient, the current displayed speed and the current converted speed. The displayed speed is obtained by rounding the converted speed after filtering out fluctuations. When the actual speed exceeds a certain threshold, the current converted speed will cause the current displayed speed to change, and the actual speed change can be captured in time. Compared with the existing solution, which takes two CAN values ​​for comparison or filtering, this patent is more stable for the speed display under precise control.

[0055] The filter coefficient can adjust relevant parameters according to different steady-state control accuracy requirements. When the steady-state control accuracy of the cruise function is poor, the value of the filter coefficient can be relatively small. It is suitable for all project development, with more flexible application and wider scope of application.

[0056] In a preferred embodiment, the converted vehicle speed after filtering is calculated using the following filtering formula (1):

[0057]

[0058] Among them, n is used to represent the acquisition period of the converted vehicle speed; It is used to indicate the converted vehicle speed after filtering in the current acquisition cycle; α is used to indicate the filtering coefficient; X(n) is used to indicate the converted vehicle speed without filtering in the current acquisition cycle; and Y(n-1) is used to indicate the displayed vehicle speed in the previous acquisition cycle.

[0059] In this embodiment, the setting of the filter coefficient α can be determined according to the control accuracy of the cruise control function on the actual vehicle. When the cruise control accuracy is lower and the vehicle speed stabilization effect is worse, the value of α needs to be smaller.

[0060] When α takes the value 1, The filtering function fails. If the current displayed speed is 59, and the converted speed after filtering (i.e. the instrument converted speed) is between 59 and 59.99, the displayed speed will not change; when the converted speed after filtering reaches 60, the displayed speed changes to 60; the converted speed after filtering changes between 59.9 and 60, which will cause the displayed speed to jump between 59 and 60. The actual speed hysteresis zone of the displayed speed change is 0, that is, as long as the converted speed after filtering exceeds 60 (the current displayed speed is 59), the displayed speed will immediately change to 60, and there is no hysteresis in the change of the displayed speed.

[0061] When α is 0.75, The filtering effect takes effect. If the current displayed speed is 59, when the converted speed after filtering is between 59 and 60.33, the displayed speed will not change; when the converted speed after filtering reaches 60.33, the displayed speed changes to 60, and when the converted speed after filtering is between 60 and 61.33, the displayed speed is 60; therefore, 60 to 60.33 is the hysteresis interval of the displayed speed, and the displayed speed will maintain the previous value within this interval.

[0062] When α is 0.5, The filtering effect takes effect. If the current displayed vehicle speed is 59, when the converted vehicle speed after filtering is between 59 and 60.99, the displayed vehicle speed will not change; when the converted vehicle speed after filtering reaches 61 and the displayed vehicle speed changes to 60, when the converted vehicle speed after filtering is between 60 and 61.99, the displayed vehicle speed is 60; therefore, 60 to 60.99 is the hysteresis interval of the displayed vehicle speed, and the displayed vehicle speed will maintain the previous value within this interval.

[0063] When functions such as fixed speed or adaptive cruise control accurately and stably control the vehicle speed, the actual vehicle speed will still fluctuate to a certain extent, so it is very important to allow a certain hysteresis interval for the actual vehicle speed change. When the actual vehicle speed fluctuates within the hysteresis interval, the unfiltered converted vehicle speed obtained by converting the actual vehicle speed is substituted into the filtering formula to obtain the filtered converted vehicle speed, which is only less than 1 higher than the existing instrument display speed. When the vehicle speed growth value is less than 1, even after rounding, the displayed vehicle speed will not increase, but continue to maintain the current display value. This method allows the actual vehicle speed to not exceed the hysteresis interval, and the actual vehicle speed change will not be immediately reflected on the instrument side. It has a certain tolerance for actual vehicle speed fluctuations. Compared with the existing solution, the processing method of taking two CAN values ​​for comparison or filtering, this patent is more stable for the speed display under precise control.

[0064] Furthermore, this solution does not adopt a processing method of comparing or filtering two CAN values, but based on a filtering formula, combines the filtering coefficient, the current displayed vehicle speed and the current converted vehicle speed to calculate the converted vehicle speed after filtering out the fluctuations. The displayed vehicle speed is rounded off according to the converted vehicle speed after filtering out the fluctuations. The change in the displayed vehicle speed is always linear without any jumps, so the change in the actual vehicle speed can be accurately reflected on this side of the instrument.

[0065] Furthermore, the filter coefficient can adjust relevant parameters according to different steady-state control accuracy requirements. When the steady-state control accuracy of the cruise function is poor, the value of the filter coefficient can be relatively small, which is suitable for all project development, more flexible in application, and has a wider range of applicability.

[0066] Specifically, when the steady-state control accuracy of the cruise function is poor, the larger the required speed hysteresis interval, the smaller the value of α can be. However, the smaller the value of α, the displayed speed will remain unchanged within a larger range of actual speed fluctuations, resulting in a greater deviation between the displayed speed and the actual speed. Therefore, when determining the value of α, we cannot simply ensure that the speed display is stable, but also need to consider the speed display effect during driving.

[0067] In a specific embodiment, after the filtering and rounding process is performed through the filtering formula, the speed display value of the instrument will jump only when the actual speed changes by more than a certain threshold. When the value of α is smaller, the threshold requirement for causing the displayed speed to change is greater. For example, when α is 0.75, examples of the unfiltered converted speed, the filtered converted speed, and the displayed speed are shown in Table 2 below:

[0068]

[0069]

[0070] Table 2: Examples of unfiltered converted speed, filtered converted speed, and displayed speed when α is 0.75

[0071] It can be seen from the changes in the displayed vehicle speed in Table 2 above that the unfiltered converted vehicle speed X(n) jumps within a certain range of the critical value, which will not cause a rapid jump in the displayed vehicle speed Y(n), and there will be no large deviation value and delay between the displayed vehicle speed Y(n) and the unfiltered converted vehicle speed X(n).

[0072] In a preferred embodiment, the above rounding process is performed by rounding up, rounding down or rounding to the nearest integer.

[0073] Specifically, the following rounding formula (2) is used to round the converted vehicle speed after filtering to obtain the displayed vehicle speed:

[0074]

[0075] Among them, Y(n) is used to represent the displayed vehicle speed in the current sampling period. Used to indicate the filtered converted vehicle speed of the current sampling period.

[0076] In this embodiment, rounding up means ignoring the rounding rule, and adding 1 to the integer in front as long as there is a decimal behind. Rounding down means ignoring the decimal as long as there is a decimal behind. For example: 4.9, calling the floor function will get 4. Calling the ceiling function will get 5.

[0077] Rounding means that if the decimal point is less than 5, it will be discarded, and if it is greater than or equal to 5, it will be rounded up. And all decimal places will be rounded up without any decimal places. For example, 99.2 will be rounded up to 99.

[0078] In summary, when functions such as fixed speed or adaptive cruise control accurately and stably control the vehicle speed, the actual vehicle speed will still fluctuate to a certain extent, so it is very important to allow a certain hysteresis interval for the actual vehicle speed change. When the actual vehicle speed fluctuates within the hysteresis interval, the unfiltered converted vehicle speed obtained by converting the actual vehicle speed is substituted into the filtering formula to obtain the filtered converted vehicle speed, which is only less than 1 higher than the existing instrument display speed. When the vehicle speed increase value is less than 1, even after rounding, the displayed vehicle speed will not increase, but continue to maintain the current display value, which can solve the rapid jump of the displayed vehicle speed value at the critical value. It can also ensure the basic consistency between the displayed vehicle speed and the actual vehicle speed, and avoid the situation where the displayed vehicle speed changes discontinuously.

[0079] like Figure 2 As shown, the present invention also provides a vehicle speed display device, including a collection setting module 1 and a conversion and rounding module 2. The cruise control accuracy is collected by the collection setting module 1, and the filter coefficient is set according to the cruise control accuracy. The cruise control accuracy is proportional to the filter coefficient. The filter coefficient, the displayed speed at the previous moment, and the unfiltered converted speed at the current moment are combined by the conversion and rounding module 2 to perform filtering processing to obtain the converted speed after filtering at the current moment; the filtered converted speed at the current moment is rounded to obtain the displayed speed at the current moment, and then displayed. The present invention can set the filter coefficient in combination with the cruise control accuracy, and calculate the converted speed after filtering the fluctuations by combining the filter coefficient, the current displayed speed, and the current converted speed. The displayed speed is obtained by rounding the converted speed after filtering the fluctuations. When the actual speed exceeds a certain threshold, the current converted speed is used to cause the current displayed speed to change, and the actual speed change can be captured in time to improve the display accuracy and stability.

[0080] In a specific embodiment, the above-mentioned vehicle speed display device includes:

[0081] The acquisition setting module 1 sets the filter coefficient according to the cruise control accuracy, and the cruise control accuracy is proportional to the filter coefficient;

[0082] The conversion and integer module 2 performs filtering processing on the filter coefficient, the displayed vehicle speed at the previous moment, and the unfiltered converted vehicle speed at the current moment to obtain the filtered converted vehicle speed at the current moment; the conversion and integer module 2 performs integer processing on the filtered converted vehicle speed at the current moment to obtain the displayed vehicle speed at the current moment, and displays it.

[0083] In this embodiment, the unfiltered converted speed of this acquisition cycle is obtained according to the actual speed in the CAN bus signal received in this acquisition cycle, and the converted speed after filtering out fluctuations is calculated by combining the filter coefficient, the current displayed speed and the current converted speed. The displayed speed is obtained by rounding the converted speed after filtering out fluctuations. When the actual speed exceeds a certain threshold, the current converted speed will cause the current displayed speed to change, and the actual speed change can be captured in time. Compared with the existing solution, which takes two CAN values ​​for comparison or filtering, this patent is more stable for the speed display under precise control.

[0084] The filter coefficient can adjust relevant parameters according to different steady-state control accuracy requirements. When the steady-state control accuracy of the cruise function is poor, the value of the filter coefficient can be relatively small. It is suitable for all project development, with more flexible application and wider scope of application.

[0085] In a preferred embodiment, the conversion and rounding module 2 uses a filtering formula to obtain the filtered converted vehicle speed at the current moment.

[0086] In this embodiment, the setting of the filter coefficient α can be determined according to the control accuracy of the cruise control function on the actual vehicle. When the cruise control accuracy is lower and the vehicle speed stabilization effect is worse, the value of α needs to be smaller.

[0087] When α takes the value 1, The filtering function fails. If the current displayed speed is 59, and the converted speed after filtering (i.e. the instrument converted speed) is between 59 and 59.99, the displayed speed will not change; when the converted speed after filtering reaches 60, the displayed speed changes to 60; the converted speed after filtering changes between 59.9 and 60, which will cause the displayed speed to jump between 59 and 60. The actual speed hysteresis zone of the displayed speed change is 0, that is, as long as the converted speed after filtering exceeds 60 (the current displayed speed is 59), the displayed speed will immediately change to 60, and there is no hysteresis in the change of the displayed speed.

[0088] When α is 0.75, The filtering effect takes effect. If the current displayed speed is 59, when the converted speed after filtering is between 59 and 60.33, the displayed speed will not change; when the converted speed after filtering reaches 60.33, the displayed speed changes to 60, and when the converted speed after filtering is between 60 and 61.33, the displayed speed is 60; therefore, 60 to 60.33 is the hysteresis interval of the displayed speed, and the displayed speed will maintain the previous value within this interval.

[0089] When α is 0.5, The filtering effect takes effect. If the current displayed vehicle speed is 59, when the converted vehicle speed after filtering is between 59 and 60.99, the displayed vehicle speed will not change; when the converted vehicle speed after filtering reaches 61 and the displayed vehicle speed changes to 60, when the converted vehicle speed after filtering is between 60 and 61.99, the displayed vehicle speed is 60; therefore, 60 to 60.99 is the hysteresis interval of the displayed vehicle speed, and the displayed vehicle speed will maintain the previous value within this interval.

[0090] When functions such as fixed speed or adaptive cruise control accurately and stably control the vehicle speed, the actual vehicle speed will still fluctuate to a certain extent, so it is very important to allow a certain hysteresis interval for the actual vehicle speed change. When the actual vehicle speed fluctuates within the hysteresis interval, the unfiltered converted vehicle speed obtained by converting the actual vehicle speed is substituted into the filtering formula to obtain the filtered converted vehicle speed, which is only less than 1 higher than the existing instrument display speed. When the vehicle speed growth value is less than 1, even after rounding, the displayed vehicle speed will not increase, but continue to maintain the current display value. This method allows the actual vehicle speed to not exceed the hysteresis interval, and the actual vehicle speed change will not be immediately reflected on the instrument side. It has a certain tolerance for actual vehicle speed fluctuations. Compared with the existing solution, the processing method of taking two CAN values ​​for comparison or filtering, this patent is more stable for the speed display under precise control.

[0091] Furthermore, this solution does not adopt a processing method of comparing or filtering two CAN values, but based on a filtering formula, combines the filtering coefficient, the current displayed vehicle speed and the current converted vehicle speed to calculate the converted vehicle speed after filtering out the fluctuations. The displayed vehicle speed is rounded off according to the converted vehicle speed after filtering out the fluctuations. The change in the displayed vehicle speed is always linear without any jumps, so the change in the actual vehicle speed can be accurately reflected on this side of the instrument.

[0092] Furthermore, the filter coefficient can adjust relevant parameters according to different steady-state control accuracy requirements. When the steady-state control accuracy of the cruise function is poor, the value of the filter coefficient can be relatively small, which is suitable for all project development, more flexible in application, and has a wider range of applicability.

[0093] Specifically, when the steady-state control accuracy of the cruise function is poor, the larger the required speed hysteresis interval, the smaller the value of α can be. However, the smaller the value of α, the displayed speed will remain unchanged within a larger range of actual speed fluctuations, resulting in a greater deviation between the displayed speed and the actual speed. Therefore, when determining the value of α, we cannot simply ensure that the speed display is stable, but also need to consider the speed display effect during driving.

[0094] In a preferred embodiment, the above-mentioned acquisition setting module 1 is also used to set the vehicle speed hysteresis zone according to the above-mentioned cruise control accuracy, and the above-mentioned cruise control accuracy is proportional to the above-mentioned vehicle speed hysteresis zone; the vehicle speed hysteresis zone is added by 1 to obtain the vehicle speed fluctuation range; the lower limit value and the upper limit value of the vehicle speed fluctuation range are respectively substituted into the above-mentioned filtering formula, and the value of the above-mentioned filtering coefficient is adjusted until the difference between the filtered converted vehicle speed of the current acquisition cycle and the displayed vehicle speed of the previous acquisition cycle is not greater than 1, thereby obtaining the set value of the filtering coefficient.

[0095] In a preferred embodiment, the value range of the above-mentioned filter coefficient is (0, 1].

[0096] In this embodiment, after the above filtering and rounding processing are performed through the filtering formula, the speed display value of the instrument will not jump until the actual speed changes by more than a certain threshold. The smaller the value of α, the greater the threshold requirement for causing the displayed speed to change.

[0097] The unfiltered converted vehicle speed X(n) jumps within a certain range of the critical value, which will not cause a rapid jump in the displayed vehicle speed Y(n), and there will be no large deviation or delay between the displayed vehicle speed Y(n) and the unfiltered converted vehicle speed X(n).

[0098] In a preferred embodiment, the above rounding process is performed by rounding up, rounding down or rounding to the nearest integer.

[0099] In this embodiment, rounding up means ignoring the rounding rule, and adding 1 to the integer in front as long as there is a decimal behind. Rounding down means ignoring the decimal as long as there is a decimal behind. For example: 4.9, calling the floor function will get 4. Calling the ceiling function will get 5.

[0100] Rounding means that if the decimal point is less than 5, it will be discarded, and if it is greater than or equal to 5, it will be rounded up. And all decimal places will be rounded up without any decimal places. For example, 99.2 will be rounded up to 99.

[0101] In summary, when functions such as fixed speed or adaptive cruise control accurately and stably control the vehicle speed, the actual vehicle speed will still fluctuate to a certain extent, so it is very important to allow a certain hysteresis interval for the actual vehicle speed change. When the actual vehicle speed fluctuates within the hysteresis interval, the unfiltered converted vehicle speed obtained by converting the actual vehicle speed is substituted into the filtering formula to obtain the filtered converted vehicle speed, which is only less than 1 higher than the existing instrument display speed. When the vehicle speed increase value is less than 1, even after rounding, the displayed vehicle speed will not increase, but continue to maintain the current display value, which can solve the rapid jump of the displayed vehicle speed value at the critical value. It can also ensure the basic consistency between the displayed vehicle speed and the actual vehicle speed, and avoid the situation where the displayed vehicle speed changes discontinuously.

[0102] The vehicle speed display device of this embodiment is applicable to the above-mentioned vehicle speed display methods.

[0103] The present application is not limited to the above-mentioned implementation modes. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A method for displaying vehicle speed, characterized in that: include: Setting a filter coefficient according to cruise control accuracy, wherein the cruise control accuracy is proportional to the filter coefficient; Perform filtering processing based on the filter coefficient, the displayed vehicle speed of the previous sampling period, and the unfiltered converted vehicle speed of the current sampling period to obtain the filtered converted vehicle speed of the current sampling period; The filtered converted vehicle speed of the current sampling period is rounded to obtain the displayed vehicle speed of the current sampling period, and then displayed; The filtered converted vehicle speed is calculated using the following filtering formula: in, n is used to indicate the acquisition period for converting vehicle speed; Used to indicate the filtered converted vehicle speed of the current acquisition cycle; α is used to represent the filter coefficient; X(n) is used to represent the unfiltered converted vehicle speed of the current acquisition period; Y(n-1) is used to represent the displayed vehicle speed in the previous acquisition cycle.

2. The method for displaying vehicle speed as claimed in claim 1, characterized in that: The setting of the filter coefficient according to the cruise control accuracy also includes: Setting a vehicle speed hysteresis zone according to the cruise control accuracy, wherein the cruise control accuracy is proportional to the vehicle speed hysteresis zone; Add 1 to the speed hysteresis zone to get the speed fluctuation range; The lower limit and upper limit of the vehicle speed fluctuation range are respectively substituted into the filtering formula, and the value of the filtering coefficient is adjusted until the difference between the filtered converted vehicle speed of the current acquisition cycle and the displayed vehicle speed of the previous acquisition cycle is no more than 1, thereby obtaining the set value of the filtering coefficient.

3. The method for displaying vehicle speed as claimed in claim 1, characterized in that: The value range of the filter coefficient is (0, 1].

4. The method for displaying vehicle speed as claimed in claim 1, characterized in that: The rounding process is to use rounding up, rounding down or rounding to the nearest integer.

5. A vehicle speed display device, characterized in that: include: A collection and setting module, which is used to set a filter coefficient according to a cruise control accuracy, wherein the cruise control accuracy is proportional to the filter coefficient; The conversion and rounding module is used to perform filtering processing on the filter coefficient, the displayed vehicle speed at the previous moment, and the unfiltered converted vehicle speed at the current moment to obtain the filtered converted vehicle speed at the current moment; and is also used to perform rounding processing on the filtered converted vehicle speed at the current moment to obtain the displayed vehicle speed at the current moment, and display it; The filtered converted vehicle speed is calculated using the following filtering formula: in, n is used to indicate the acquisition period for converting vehicle speed; Used to indicate the filtered converted vehicle speed of the current acquisition cycle; α is used to represent the filter coefficient; X(n) is used to represent the unfiltered converted vehicle speed of the current acquisition period; Y(n-1) is used to represent the displayed vehicle speed in the previous acquisition cycle.

6. The vehicle speed display device according to claim 5, characterized in that: The acquisition setting module is also used to set a vehicle speed hysteresis zone according to the cruise control accuracy, and the cruise control accuracy is proportional to the vehicle speed hysteresis zone; add 1 to the vehicle speed hysteresis zone to obtain a vehicle speed fluctuation range; substitute the lower limit value and the upper limit value of the vehicle speed fluctuation range into the filtering formula respectively, and adjust the value of the filtering coefficient until the difference between the filtered converted vehicle speed of the current acquisition cycle and the displayed vehicle speed of the previous acquisition cycle is no more than 1, thereby obtaining a set value of the filtering coefficient.

7. The vehicle speed display device according to claim 6, characterized in that: The value range of the filter coefficient is (0, 1].

8. The vehicle speed display device according to claim 5, characterized in that: The rounding process is to use rounding up, rounding down or rounding to the nearest integer.

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