Braking force strategy determination method and control method in vehicle starting process

Abstract

The embodiment of the invention discloses a method for determining a braking force strategy in a vehicle starting process and a method for controlling the braking force strategy in the vehicle starting process, noise performance in the starting process is determined by conducting noise testing on the vehicle starting process according to an initial starting strategy, and the braking force strategy is determined according to the noise performance in the starting process. And increasing the change speed of the braking force under at least part of pedal angles in the initial starting strategy to suppress noise, and obtaining a braking force strategy. Therefore, when the vehicle is started according to the obtained braking force strategy, in the lifting process of the brake pedal, the vehicle can quickly pass through a braking force point with poor noise performance, the sound pressure of the noise is reduced or the duration of the noise is shortened, and then starting wriggling noise is restrained.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a method for determining and controlling the braking force strategy during vehicle start-up. Background Technology

[0002] With the development of vehicle technology, the issue of starting noise during vehicle start-up is increasingly attracting users' attention.

[0003] The mechanism of starting creep noise is due to the stick-slip motion generated by the friction pair on the sliding surface, resulting in obvious vibration noise. During vehicle start-up, the brake pedal is gradually lifted, and the starting creep noise is usually more obvious when the brake pedal is at a certain pedal angle.

[0004] Therefore, how to suppress start-up creep noise has become an urgent problem to be solved. Summary of the Invention

[0005] This invention provides a method for determining and controlling the braking force strategy during vehicle start-up, in order to suppress noise during vehicle start-up and improve user experience.

[0006] According to one aspect of the present invention, a method for determining braking force strategy during vehicle start-up is provided, comprising:

[0007] The noise performance of the vehicle during the starting process is determined by conducting noise tests based on the initial starting strategy; the initial starting strategy includes the first correspondence between the vehicle's braking force and the brake pedal angle.

[0008] Based on the noise performance during the start-up process, the rate of change of braking force at at least a portion of the pedal angle in the initial start-up strategy is increased to suppress noise, resulting in a braking force strategy; the braking force strategy includes a second correspondence between the vehicle's braking force and the pedal angle of the brake pedal.

[0009] Optionally, the first correspondence is a linear relationship; based on the noise performance during the start-up process, the rate of change of braking force at at least a portion of the pedal angles in the initial start-up strategy is increased to suppress noise, resulting in a braking force strategy, including:

[0010] Based on the noise performance during the start-up process, determine the critical points of braking force for dynamic and static friction between the friction pads and the brake disc;

[0011] By increasing the absolute value of the slope of the first correspondence between the pedal angle and the braking force at the critical point of the initial start-up strategy, the braking force strategy is obtained.

[0012] Optionally, based on the noise performance during start-up, determine the critical points of braking force at which dynamic and static friction occurs between the friction pads and the brake disc, including:

[0013] Based on the noise performance during the start-up process, the noise mutation point is determined. The noise mutation point is the time point when the noise sound pressure increases beyond a set threshold.

[0014] The braking force corresponding to the noise mutation point is determined as the braking force critical point.

[0015] Optionally, by increasing the absolute value of the slope of the relationship between the pedal angle and braking force at the critical point of braking force in the initial start-up strategy, a braking force strategy can be obtained, including:

[0016] The absolute value of the slope of the first correspondence between pedal angle and braking force under the increased set pedal angle range, wherein the set pedal angle range includes the pedal angle corresponding to the critical point of braking force in the initial start strategy;

[0017] Maintain the slope of the first correspondence between pedal angle and braking force within the first pedal angle range, and maintain or reduce the slope of the first correspondence between pedal angle and braking force within the second pedal angle range.

[0018] Wherein, the maximum value of the pedal angle in the first pedal angle range is equal to the minimum value of the pedal angle in the set pedal angle range; the minimum value of the pedal angle in the second pedal angle range is greater than or equal to the maximum value of the pedal angle in the set pedal angle range.

[0019] Optionally, the minimum value of the pedal angle within the set pedal angle range is less than or equal to the pedal angle corresponding to the braking force critical point in the initial start-up strategy, and the maximum value of the pedal angle within the set pedal angle range is greater than the pedal angle corresponding to the braking force critical point in the initial start-up strategy.

[0020] Optionally, based on the noise performance during the start-up process, the rate of change of braking force at at least a portion of the pedal angles in the initial start-up strategy is increased to suppress noise, resulting in a braking force strategy, including:

[0021] Based on the noise performance during the start-up process, the noise mutation point is determined. The noise mutation point is the time point when the noise sound pressure increases beyond a set threshold.

[0022] By increasing the absolute value of the slope of the relationship between the pedal angle and braking force corresponding to the noise mutation point in the initial start-up strategy, the braking force strategy is obtained.

[0023] Optionally, noise testing is performed on the vehicle's starting process based on the initial starting strategy to determine the noise performance during the starting process, including:

[0024] Perform at least two noise tests on the vehicle start-up process based on the initial start-up strategy;

[0025] The noise performance during vehicle start-up is scored based on the noise intensity and duration during the brake pedal release process.

[0026] Before obtaining the braking force strategy, which involves adjusting the initial start-up strategy based on noise performance during the start-up process and increasing the rate of change of braking force at at least a portion of the pedal angle to suppress noise, the following steps are also included:

[0027] Determine whether the noise performance score meets the requirements;

[0028] If not, continue to execute the initial start-up strategy based on the noise performance during the start-up process, increase the rate of change of braking force at at least part of the pedal angle to suppress noise, and obtain the braking force strategy.

[0029] Optionally, before conducting at least two noise tests on the vehicle start-up process according to the initial start-up strategy, the following may also be included:

[0030] Controls the closing of the vehicle's windows and the shutdown of the vehicle's onboard systems.

[0031] Optionally, after adjusting the initial start-up strategy based on noise performance during start-up, and increasing the rate of change of braking force at at least a portion of the pedal angle to suppress noise, the braking force strategy includes:

[0032] Based on the received adjustment instructions, the rate of change of braking force at at least some pedal angles in the braking force strategy is adjusted to suppress noise or increase the smoothness of the vehicle's start-up process, resulting in an updated braking force strategy.

[0033] According to another aspect of the present invention, a control method for a vehicle starting process is provided, comprising: starting the vehicle using a braking force strategy determined by a braking force strategy determination method for a vehicle starting process according to any embodiment of the present invention.

[0034] The braking force strategy determination and control method for vehicle starting process according to embodiments of the present invention determines the noise performance during the starting process by conducting noise tests on the vehicle based on an initial starting strategy. Based on the noise performance during starting, the rate of change of braking force at at least a portion of the pedal angles in the initial starting strategy is increased to suppress noise, thus obtaining a braking force strategy. Therefore, when starting the vehicle according to the obtained braking force strategy, the brake pedal can quickly pass through braking points with poor noise performance during the release process, reducing the sound pressure level or shortening the duration of the noise, thereby suppressing starting creep noise.

[0035] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of a method for determining braking force strategy during vehicle start-up provided by an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the first correspondence;

[0039] Figure 3 This is a flowchart of another method for determining the braking force strategy during vehicle start-up provided in an embodiment of the present invention;

[0040] Figure 4 These are curves showing the three scenarios of starting creep noise;

[0041] Figure 5 This is a schematic diagram of the second and first correspondence relationships;

[0042] Figure 6 This is a flowchart of another method for determining the braking force strategy during vehicle start-up provided by an embodiment of the present invention;

[0043] Figure 7 This is a flowchart of another method for determining the braking force strategy during vehicle start-up provided by an embodiment of the present invention. Detailed Implementation

[0044] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0046] Figure 1 This is a flowchart illustrating a method for determining a braking force strategy during vehicle start-up, provided by an embodiment of the present invention. This method can be executed by a braking force strategy determination device, which can be implemented through software and / or hardware. The method can be used to determine the braking force strategy during vehicle start-up, including the relationship between braking force and the brake pedal angle, to suppress creep noise during vehicle start-up. (Reference) Figure 1 The method for determining the braking force strategy during the vehicle's start-up process includes:

[0047] S110. Conduct noise tests on the vehicle's starting process according to the initial starting strategy to determine the noise performance during the starting process.

[0048] The initial start-up strategy includes the first correspondence between the vehicle's braking force and the brake pedal angle.

[0049] The initial start-up strategy can be preset. Optionally, the first correspondence between the vehicle's braking force and the pedal angle in the initial start-up strategy is a linear relationship. Figure 2 This is a schematic diagram of the first correspondence, with Figure 2 Taking the illustrated example, the relationship between the pedal angle and the vehicle's braking force can be a straight line. In other optional embodiments of the present invention, the first correspondence can also be a piecewise linear relationship. Because the brake pedal is depressed to the floor and then lifted during vehicle start-up, in this embodiment of the present invention, the state where the brake pedal is depressed to the floor can be defined as 0 degrees of pedal angle, and as the brake pedal is lifted, the pedal angle gradually increases.

[0050] Specifically, in this step, a noise test can be performed on the vehicle's starting process. This noise test may include, but is not limited to, noise, vibration, and sound roughness tests, collectively referred to as NVH testing. During the noise test, the vehicle is first driven to the test position, then the brake pedal is fully depressed and slowly released. The noise level during this release process is recorded, providing the noise performance during the starting process. This noise performance can include the noise levels at multiple pedal angles. Noise can be acquired by installing a sound pressure sensor, which accurately obtains the specific sound pressure value. Alternatively, noise can be acquired through the tester's perception. While this doesn't provide an accurate sound pressure value, the relative sound pressure level can be obtained based on human perception. For example, the noise sound pressure levels at different brake pedal angles can be ranked to determine the relative magnitudes of the noise sound pressure at different brake pedal angles. In some optional embodiments of this invention, the noise performance may include the noise performance of the front axle and / or rear axle of the vehicle.

[0051] S120. Based on the noise performance during the start-up process, increase the rate of change of braking force at at least part of the pedal angle in the initial start-up strategy to suppress noise, thus obtaining the braking force strategy.

[0052] Among them, the braking force strategy includes a second correspondence between the vehicle's braking force and the pedal angle of the brake pedal.

[0053] In this step, based on the noise performance during the initial start-up process under the initial start-up strategy, the initial start-up strategy can be adjusted, resulting in the braking force strategy. Specifically, based on the noise performance during the start-up process under the initial start-up strategy, the relationship between the pedal angle and braking force at the pedal angle with poor noise performance can be adjusted so that the brake pedal can quickly pass through the braking force point with poor noise performance during the release process. Specifically, based on the noise performance during the start-up process, the rate of change of braking force at the pedal angle with poor noise performance in the initial start-up strategy is increased to suppress noise, obtaining a second correspondence between the vehicle's braking force and the brake pedal angle, i.e., obtaining the braking force strategy.

[0054] Poor noise performance includes noise sound pressure exceeding a sound pressure threshold and / or a sudden increase in noise sound pressure. A sudden increase in noise sound pressure occurs when the difference between the noise sound pressure measured in two consecutive measurements exceeds a set threshold. By increasing the rate of change of braking force at the pedal angle where noise performance is poor, the braking force point corresponding to the pedal angle with poor noise performance under the initial start-up strategy can be quickly passed, reducing the noise sound pressure or shortening the duration of the noise, thereby suppressing start-up creep noise.

[0055] The braking force strategy determination method for vehicle starting process in this embodiment involves conducting noise tests on the vehicle's starting process based on an initial starting strategy to determine the noise performance during starting. Based on this noise performance, the method increases the rate of change of braking force at at least a portion of the pedal angles in the initial starting strategy to suppress noise, thus obtaining the braking force strategy. Therefore, when starting the vehicle according to the obtained braking force strategy, the brake pedal can quickly pass through braking points with poor noise performance during the release process, reducing the sound pressure level or shortening the duration of the noise, thereby suppressing starting creep noise.

[0056] Figure 3 This is a flowchart of another method for determining braking force strategy during vehicle start-up provided by an embodiment of the present invention, referred to [reference]. Figure 3 The method for determining the braking force strategy during the vehicle's start-up process includes:

[0057] S210. Conduct noise tests on the vehicle's starting process according to the initial starting strategy to determine the noise performance during the starting process.

[0058] The initial starting strategy includes a first correspondence between the vehicle's braking force and the brake pedal angle.

[0059] S220. Based on the noise performance during the starting process, determine the critical points of braking force for dynamic and static friction between the friction pads and the brake disc.

[0060] The mechanism of creep noise during start-up is due to the stick-slip motion generated by the friction pair on the sliding surface, which leads to significant vibration noise. This stick-slip motion is caused by the excessive difference between the dynamic and static friction coefficients of the friction pair. The friction pads and brake disc continuously switch between dynamic and static friction, and this switching process introduces fluctuations in dynamic and static friction forces, thus triggering creep noise. Therefore, determining the critical braking force points corresponding to the dynamic and static friction of the friction pads and brake disc, and quickly passing through these critical braking force points, helps to suppress creep noise.

[0061] In some optional embodiments of the present invention, the noise mutation point can be determined based on the noise performance during the start-up process, wherein the noise mutation point is the time point when the noise sound pressure increases beyond a set threshold; and the braking force corresponding to the noise mutation point is determined as the braking force critical point.

[0062] Specifically, during vehicle start-up, as the brake pedal is released, noise pressure can be collected in real time using a sound pressure sensor. The change in noise pressure is calculated by comparing the noise pressure detected by the sensor with the previously collected noise pressure. In this step, the point at which the noise pressure increases beyond a set threshold is defined as the noise abrupt change point; that is, the point at which the difference between the collected and previously collected noise pressure exceeds the set threshold is defined as the noise abrupt change point. The braking force corresponding to the noise abrupt change point is then determined, and this braking force is defined as the braking force critical point. During noise testing, the relationship between time, noise pressure, pedal angle, and braking force can be acquired and stored. Each noise abrupt change point corresponds to a specific time point; once the noise abrupt change point is determined, the corresponding pedal angle and braking force can be determined based on this time point.

[0063] Figure 4 These are graphs showing the noise levels during startup for three different scenarios. (Reference) Figure 4 The curve for the first time period t1 corresponds to a single starting creep noise, the curve for the second time period t2 corresponds to a continuous starting creep noise over a short period of time, and the curve for the third time period t3 corresponds to the resonant starting creep noise caused by the vehicle system. According to Figure 4 As can be seen, since the sound pressure level corresponding to the initial creep noise is relatively high, in this step, determining the braking force corresponding to the noise abrupt change point as the braking force critical point can ensure the accuracy of the determined braking force critical point. It should be noted that... Figure 4 The sound pressure waveforms of the initial creep noise are illustrated for only three scenarios. Figure 4 The three curves may not all exist in a single start-up process.

[0064] In other alternative embodiments of the present invention, during the NVH test of a vehicle, the tester can also find the critical point of braking force for dynamic friction and static friction based on actual testing experience.

[0065] S230. In the initial starting strategy, the absolute value of the slope of the first correspondence between the pedal angle at the critical point of braking force and the braking force is increased to obtain the braking force strategy.

[0066] Specifically, in the initial start-up strategy, the relationship between the vehicle's braking force and the pedal angle is linear, meaning it can be represented by a straight line or a segmented straight line. By increasing the slope of the straight line at the braking force critical point in the first linear relationship between the vehicle's braking force and the pedal angle in the initial start-up strategy, the speed at which the braking force critical point is passed during the brake pedal release process can be increased. This allows for a faster passage through the braking force critical point, thereby suppressing start-up creep noise. For example, in the initial start-up strategy, the slope corresponding to the braking force critical point in the first linear relationship is k1; in the braking force strategy obtained from the initial start-up strategy, the slope corresponding to the braking force critical point in the second linear relationship is k2, where |k2|>|k1|.

[0067] Optionally, S230 includes: increasing the absolute value of the slope of the first correspondence between pedal angle and braking force within a set pedal angle range, wherein the set pedal angle range includes the pedal angle corresponding to the braking force critical point in the initial start-up strategy; maintaining the slope of the first correspondence between pedal angle and braking force within the first pedal angle range, and maintaining or decreasing the slope of the first correspondence between pedal angle and braking force within a second pedal angle range; wherein the maximum value of the pedal angle in the first pedal angle range is equal to the minimum value of the pedal angle in the set pedal angle range; and the minimum value of the pedal angle in the second pedal angle range is greater than or equal to the maximum value of the pedal angle in the set pedal angle range. Figure 5 This is a schematic diagram of the second and first correspondence relationships, as shown below. Figure 5 As shown, at the critical point of dynamic and static friction, the absolute value of the slope of the second correspondence line 12 corresponding to the second correspondence is greater than the absolute value of the slope of the first correspondence line 11.

[0068] By maintaining the slope of the first correspondence between pedal angle and braking force within the first pedal angle range, and increasing the absolute value of the slope in this first correspondence, the braking force change at the critical point can be increased relative to the initial starting strategy's first correspondence, allowing for a faster passage through the braking force critical point and suppressing starting creep noise. By maintaining the slope of the first correspondence between pedal angle and braking force within the first pedal angle range, and maintaining or decreasing the slope of the first correspondence between pedal angle and braking force within the second pedal angle range, the rate of change of braking force with pedal angle within both ranges can be prevented from being too rapid. This helps ensure smoothness during starting and further improves the user experience.

[0069] Optionally, the minimum pedal angle within the set pedal angle range is less than or equal to the pedal angle corresponding to the braking force critical point in the initial start-up strategy, and the maximum pedal angle within the set pedal angle range is greater than the pedal angle corresponding to the braking force critical point in the initial start-up strategy. This ensures that when the braking force critical point is not reached or has just been reached, the rate at which the braking force changes with the pedal angle is accelerated, and that the rate at which the braking force changes with the pedal angle only slows down after the braking force critical point. This ensures that within a braking force range including the braking force critical point, the rate at which the braking force changes with the pedal angle is accelerated, allowing the braking force range, including the braking force critical point, to be quickly passed during the brake pedal release process, which helps to further suppress creep noise.

[0070] In some alternative embodiments of the present invention, S120 includes determining a noise abrupt change point based on the noise performance during the start-up process, wherein the noise abrupt change point is the time point at which the noise sound pressure increases beyond a set threshold; increasing the absolute value of the slope of the relationship between the pedal angle and braking force corresponding to the noise abrupt change point in the initial start-up strategy to obtain a braking force strategy. That is, compared to the above embodiments, in this embodiment, the braking force critical point is not determined, and the absolute value of the slope of the relationship between the pedal angle and braking force corresponding to the noise abrupt change point in the initial start-up strategy is directly increased, so that the braking force point corresponding to the noise abrupt change point passes quickly during the lifting of the vehicle's start-up brake pedal, which is beneficial for suppressing start-up creep noise.

[0071] Figure 6 This is a flowchart of another method for determining the braking force strategy during vehicle start-up provided by an embodiment of the present invention, referred to [reference]. Figure 6 The method for determining the braking force strategy during the vehicle's start-up process includes:

[0072] S310. Perform at least two noise tests on the vehicle start-up process according to the initial start-up strategy.

[0073] In some optional embodiments of the present invention, at least five noise tests are performed on the vehicle starting process based on the initial starting profile to avoid the braking force strategy being unable to suppress creep noise due to inaccurate results of a single noise test.

[0074] S320. The noise performance during vehicle start-up is scored based on the noise intensity and duration during the brake pedal release process.

[0075] Optionally, a base score for noise performance is first determined based on noise intensity. Points are then deducted based on the duration of the noise. Table 1 shows the scoring table corresponding to the base score. For example, noise intensity corresponds to noise perception, which can be categorized into unacceptable, borderline, and acceptable levels. The unacceptable level corresponds to three levels of noise perception: extremely loud, very loud, and loud. Extremely loud corresponds to a score of 1 or 2 points, very loud corresponds to a score of 3, 4, or 5 points, and loud corresponds to a score of 6 points. Borderline noise perception is just acceptable, with a score of 7 points. Acceptable noise perception is light, very light, or absent, with corresponding scores of 8, 9, or 10 points, respectively.

[0076] Table 1

[0077]

[0078] Table 2 shows the deductions based on the duration of the noise. If the noise is continuous, 1.5 to 2 points are deducted. If the noise is likely to continue, 1 to 1.5 points are deducted; if the noise is not likely to continue, 0.5 to 1 point are deducted; if the noise is not sustainable, no points are deducted.

[0079] Table 2

[0080] Sustainable Easy to sustain Not easy to sustain Unable to continue Deduct 1.5 to 2 points Deduct 1 to 1.5 points. Deduct 0.5 to 1 point. No points deducted

[0081] In addition, if the starting creep noise continues and causes vibrations in the steering wheel or dashboard, points can be deducted from the final score.

[0082] It should be noted that the above scoring method can be based on the subjective feelings of the tester during the testing process. In other optional embodiments of the present invention, noise intensity can be characterized by noise sound pressure. By dividing the noise sound pressure into at least two levels and the noise duration into at least two levels, and acquiring the noise sound pressure through a sound pressure sensor, a quantitative score is performed based on the sound pressure level to which the noise intensity belongs during the vehicle brake pedal release process and the duration level to which the noise duration belongs.

[0083] S330. Determine whether the noise performance score meets the requirements.

[0084] If not, continue with S340, adjust the initial start strategy based on the noise performance during the start-up process, increase the rate of change of braking force at at least part of the pedal angle to reduce noise, and obtain the braking force strategy.

[0085] If so, then the noise test is considered passed.

[0086] Specifically, a scoring threshold can be set, and if the noise performance score is greater than or equal to the scoring threshold, the noise performance score is determined to meet the requirements.

[0087] Optionally, before and during noise testing, the process may also include: controlling the closing of vehicle windows and the shutdown of the vehicle's onboard systems. This can prevent external noise or onboard system noise from affecting the noise test and improve its accuracy.

[0088] Based on the above embodiments, after S120, S230 and S340, the method further includes: adjusting the rate of change of braking force at at least a portion of the pedal angles in the braking force strategy according to the received adjustment instructions to reduce noise or increase the smoothness of the vehicle start-up process, thereby obtaining an updated braking force strategy.

[0089] Specifically, during vehicle start-up, the comfort of the driver and passengers must also be considered. If the rate of change of braking force with pedal angle is too large, the driver and passengers will experience a jerking sensation, resulting in poor comfort. Furthermore, the start-up process may also introduce or exacerbate other noises. If either of these situations occurs, the tester can issue an adjustment command to the braking force strategy determination device. Upon receiving the adjustment command, the device can adjust the rate of change of braking force at at least a portion of the pedal angles in the braking force strategy, for example, by reducing the rate of change of braking force at at least a portion of the pedal angles, to reduce noise or increase the smoothness of the vehicle start-up process, thus obtaining an updated braking force strategy.

[0090] Figure 7 This is a flowchart of another method for determining the braking force strategy during vehicle start-up provided by an embodiment of the present invention, referred to [reference]. Figure 7 The method for determining the braking force strategy during the vehicle's start-up process includes:

[0091] S410. Perform a full vehicle NVH test on the vehicle's starting process according to the initial starting strategy to determine whether there is a starting creep noise problem.

[0092] If yes, execute S420. If no, end the braking force strategy determination process and determine the initial start-up strategy as the braking force strategy.

[0093] Based on the above embodiments, if the noise performance score does not meet the requirements, it is determined that there is a start-up creep noise problem; if the noise performance score meets the requirements, it is determined that there is no start-up creep noise problem.

[0094] S420. Determine the critical point of braking force when dynamic and static friction occurs between the friction pads and the brake disc.

[0095] S430, Adjust braking force strategy.

[0096] The braking force strategy adjusted in this step includes the initial start-up strategy and the braking force strategy after adjusting the initial start-up strategy.

[0097] Specifically, when adjusting the initial start-up strategy, the rate of change of braking force at the pedal angle at the critical braking force point can be increased. This means increasing the absolute value of the slope of the first correspondence between the pedal angle and braking force at the critical braking force point in the initial start-up strategy, thus obtaining the braking force strategy. When adjusting the braking force strategy obtained after adjusting the initial start-up strategy, the rate of change of braking force at certain pedal angles can be increased or decreased.

[0098] S440: Control the vehicle's starting process according to the braking force strategy to determine whether the driver and passengers' comfort during the starting process meets the requirements.

[0099] If yes, proceed to S450. If no, return to S430.

[0100] Whether the comfort of the driver and passengers during the start-up process meets the requirements can be determined by installing vibration sensors in the vehicle and measuring the relationship between the vibration values ​​and the preset vibration threshold; alternatively, it can be determined based on the subjective feelings of the driver and passengers.

[0101] S450: Determine whether the starting process generates or aggravates noise other than starting creep noise. If yes, return to execute S430. If no, the method for determining the braking force strategy during vehicle starting ends, and the final braking force strategy is obtained.

[0102] Specifically, sound pressure sensors can be installed at different locations on the vehicle to detect noise at different locations. Then, based on the sound pressure detected by the sound pressure sensors, it can be determined whether the starting process generates or aggravates other noises besides the starting creep noise. Alternatively, it can be determined based on the subjective feeling of the test personnel whether other noises besides the starting creep noise are generated or aggravated. This embodiment of the invention does not make specific limitations here.

[0103] The braking force strategy determination method for vehicle start-up in this embodiment can not only suppress start-up creep noise, but also further ensure the comfort of the driver and passengers, and ensure that other noises during the start-up process are relatively low, thereby further improving the user experience.

[0104] This invention also provides a control method for a vehicle starting process. The control method for a vehicle starting process includes: starting the vehicle according to a braking force strategy, wherein the braking force strategy is determined according to the braking force strategy determination method for the vehicle starting process of any of the above embodiments of this invention, and has the beneficial effects of the braking force strategy determination method for the vehicle starting process of any of the above embodiments of this invention, which will not be elaborated here.

[0105] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0106] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for determining braking force strategy during vehicle start-up, characterized in that, include: The noise performance of the vehicle during the starting process is determined by conducting a noise test based on the initial starting strategy; wherein the initial starting strategy includes a first correspondence between the vehicle's braking force and the brake pedal angle. Based on the noise performance during the start-up process, the rate of change of braking force at at least a portion of the pedal angles in the initial start-up strategy is increased to suppress noise, thereby obtaining the braking force strategy; the braking force strategy includes a second correspondence between the vehicle's braking force and the pedal angle of the brake pedal.

2. The method for determining braking force strategy during vehicle start-up as described in claim 1, characterized in that, The first correspondence is a linear relationship; the step of increasing the rate of change of braking force at at least a portion of the pedal angles in the initial start-up strategy to suppress noise, based on the noise performance during the start-up process, to obtain the braking force strategy, includes: Based on the noise performance during the starting process, the critical points of braking force for dynamic and static friction between the friction pads and the brake disc are determined. The braking force strategy is obtained by increasing the absolute value of the slope of the first correspondence between the pedal angle and the braking force at the critical point of the braking force in the initial start-up strategy.

3. The method for determining braking force strategy during vehicle start-up according to claim 2, characterized in that, The determination of the critical points of braking force for dynamic and static friction between the friction pads and the brake disc based on the noise performance during the starting process includes: Based on the noise performance during the start-up process, the noise mutation point is determined, wherein the noise mutation point is the time point when the noise sound pressure increases beyond a set threshold. The braking force corresponding to the noise mutation point is determined as the braking force critical point.

4. The method for determining braking force strategy during vehicle start-up according to claim 2, characterized in that, The method of increasing the absolute value of the slope of the relationship between the pedal angle and the braking force at the critical point of the braking force in the initial start-up strategy to obtain the braking force strategy includes: The absolute value of the slope of the first correspondence between the pedal angle and the braking force under the increased set pedal angle range, wherein the set pedal angle range includes the pedal angle corresponding to the critical point of the braking force in the initial start strategy; Maintain the slope of the first correspondence between the pedal angle and the braking force within the first pedal angle range, and maintain or reduce the slope of the first correspondence between the pedal angle and the braking force within the second pedal angle range; Wherein, the maximum value of the pedal angle in the first pedal angle range is equal to the minimum value of the pedal angle in the set pedal angle range; the minimum value of the pedal angle in the second pedal angle range is greater than or equal to the maximum value of the pedal angle in the set pedal angle range.

5. The method for determining braking force strategy during vehicle start-up according to claim 4, characterized in that, The minimum value of the pedal angle within the set pedal angle range is less than or equal to the pedal angle corresponding to the braking force critical point in the initial start-up strategy, and the maximum value of the pedal angle within the set pedal angle range is greater than the pedal angle corresponding to the braking force critical point in the initial start-up strategy.

6. The method for determining braking force strategy during vehicle start-up according to claim 1, characterized in that, The method of increasing the rate of change of braking force at at least a portion of the pedal angles in the initial start-up strategy to suppress noise, based on the noise performance during the start-up process, to obtain the braking force strategy, includes: Based on the noise performance during the start-up process, the noise mutation point is determined, wherein the noise mutation point is the time point when the noise sound pressure increases beyond a set threshold. Increasing the absolute value of the slope of the relationship between the pedal angle and the braking force corresponding to the noise mutation point in the initial start-up strategy yields the braking force strategy.

7. The method for determining the braking force strategy during vehicle start-up according to claim 1, characterized in that, The step of conducting noise testing on the vehicle's starting process based on the initial starting strategy to determine the noise performance during the starting process includes: Perform at least two noise tests on the vehicle start-up process according to the initial start-up strategy; The noise performance during vehicle start-up is scored based on the noise intensity and duration during the brake pedal release process. Before adjusting the initial start-up strategy based on the noise performance during the start-up process, and increasing the rate of change of braking force at at least a portion of the pedal angle to suppress noise, to obtain the braking force strategy, the method further includes: Determine whether the score for the noise performance meets the requirements; If not, then continue to execute the initial start strategy based on the noise performance during the start-up process, increase the rate of change of braking force at at least part of the pedal angle to suppress noise, and obtain the braking force strategy.

8. The method for determining braking force strategy during vehicle start-up according to claim 7, characterized in that, Before conducting at least two noise tests on the vehicle start-up process according to the initial start-up strategy, the method further includes: Control the closing of the vehicle's windows and control the shutdown of the vehicle's onboard systems.

9. The method for determining braking force strategy during vehicle start-up according to claim 1, characterized in that, After adjusting the initial start-up strategy based on the noise performance during the start-up process, and increasing the rate of change of braking force at at least a portion of the pedal angle to suppress noise, and obtaining the braking force strategy, the process includes: Based on the received adjustment instructions, the rate of change of braking force at at least a portion of the pedal angles in the braking force strategy is adjusted to suppress noise or increase the smoothness of the vehicle's start-up process, resulting in an updated braking force strategy.

10. A control method for the vehicle starting process, characterized in that, include: The braking force strategy determined by the method for determining the braking force strategy during the vehicle starting process according to any one of claims 1-9 is used to start the vehicle.

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