Target wheel cylinder pressure calibration method and device, electronic equipment and storage medium

Abstract

The invention provides a target wheel cylinder pressure calibration method and device, electronic equipment and a storage medium, the method is applied to a vehicle, the vehicle comprises a wheel cylinder, the wheel cylinder is used for braking the vehicle, and the method comprises the steps that firstly, the theoretical wheel cylinder pressure that the vehicle can be parked on a target ramp is determined; and then the theoretical wheel cylinder pressure is compensated according to the attenuation value of the wheel cylinder pressure, and the target wheel cylinder pressure with the automatic parking function is obtained. When the automatic parking function is activated, the vehicle is braked through the target wheel cylinder pressure, and the risk that the vehicle slides on a slope can be reduced.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a target wheel cylinder pressure calibration method, device, electronic device and storage medium. Background Art

[0002] The vehicle's automatic parking function can keep the vehicle stopped on flat ground or slopes without the driver having to keep the brake pedal depressed or use the handbrake to keep the vehicle stopped.

[0003] The basic principle of the automatic parking function is: the brake pressure received by the brake master cylinder is converted into liquid pressure by the hydraulic control unit and transmitted to the wheel cylinder. The piston in the wheel cylinder moves due to the liquid pressure, pushing the brake pad to stop the vehicle.

[0004] When the electronic stability control system detects that the brake pressure reaches the target pressure (normally, when the brake pressure reaches the target pressure, the vehicle can obtain the tire circumferential braking force required to stop), the hydraulic control unit in the brake system will close the pressure-maintaining valve, closing the hydraulic circuit between the brake master cylinder and the wheel cylinder, so that the liquid pressure in the wheel cylinder remains unchanged, thereby achieving vehicle stationary parking.

[0005] However, due to problems such as the production process of the pressure-maintaining valve, the fluid in the hydraulic circuit may leak. The fluid leakage in the hydraulic circuit will cause the fluid pressure in the hydraulic circuit to decay. When the automatic parking function is used, due to the decay of the fluid pressure, when the brake pressure reaches the target pressure, the tire circumference braking force obtained by the vehicle may not be enough to stop the vehicle, causing the vehicle to slide down the slope.

[0006] It should be pointed out that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0007] The present application provides a target wheel cylinder pressure calibration method, device, electronic device and storage medium, so as to solve the problem that a vehicle may roll down a slope due to leakage of a pressure-maintaining valve when using an automatic parking function.

[0008] In a first aspect, an embodiment of the present application provides a method for calibrating a target wheel cylinder pressure of an automatic parking function, comprising:

[0009] Applied to a vehicle, the vehicle includes a wheel cylinder, the wheel cylinder is used to brake the vehicle, the method includes:

[0010] At a first moment, obtaining a theoretical wheel cylinder pressure of the wheel cylinder, wherein the theoretical wheel cylinder pressure is a critical value for enabling the vehicle to stop on a target slope;

[0011] Determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force;

[0012] At a second moment, the vehicle is braked using the theoretical wheel cylinder pressure, and a target tire peripheral driving force is obtained, where the target tire peripheral driving force is a critical value applied to the tire periphery to allow the vehicle to move;

[0013] determining an attenuation value of the tire peripheral braking force according to a difference between the tire peripheral braking force and the target tire peripheral driving force;

[0014] Determining a first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and a mapping relationship between the wheel cylinder pressure and the tire peripheral braking force;

[0015] A target wheel cylinder pressure for an automatic parking function is determined based on the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

[0016] In a possible implementation, the vehicle maintains a braking state during the period from the first moment to the second moment.

[0017] In a possible implementation, during the period from the first moment to the second moment, the vehicle maintains a braking state under the theoretical wheel cylinder pressure.

[0018] In a possible implementation, determining a target wheel cylinder pressure of an automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure includes:

[0019] determining a decay rate of the wheel cylinder pressure according to a first decay value and a first time duration of the wheel cylinder pressure, wherein the first time duration is a time duration from the first moment to the second moment;

[0020] determining a second attenuation value of the wheel cylinder pressure according to the attenuation rate of the wheel cylinder pressure and a second time period, wherein the second time period is a time period from the first moment to the current moment;

[0021] A target wheel cylinder pressure for an automatic parking function is determined based on the second attenuation value of the wheel cylinder pressure and the theoretical wheel cylinder pressure.

[0022] In a possible implementation, the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force is as follows:

[0023]

[0024] Among them, F b is the braking force around the tire, F is the wheel cylinder pressure, BF is the braking efficiency factor, r is the brake action radius, and R is the tire static radius.

[0025] In a possible implementation, obtaining the theoretical wheel cylinder pressure of the wheel cylinder includes:

[0026] On the target slope, the automatic parking function is turned off, and the wheel cylinder pressure is controlled to be gradually reduced until the wheel movement is detected, and the current wheel cylinder pressure of the wheel cylinder is determined to be the theoretical wheel cylinder pressure.

[0027] In a possible implementation, obtaining the target tire peripheral driving force includes:

[0028] The tire peripheral driving force is controlled to gradually increase until the wheel movement is detected, and the current tire peripheral driving force is determined to be the target tire peripheral driving force.

[0029] In a second aspect, an embodiment of the present application provides a target wheel cylinder pressure calibration device for an automatic parking function, which is applied to a vehicle, wherein the vehicle includes a wheel cylinder, and the wheel cylinder is used to brake the vehicle, and the device includes:

[0030] a theoretical wheel cylinder pressure acquisition module, configured to acquire a theoretical wheel cylinder pressure of the wheel cylinder at a first moment, wherein the theoretical wheel cylinder pressure is a critical value for enabling the vehicle to stop on a target slope;

[0031] A tire peripheral braking force determination module, used to determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force;

[0032] a target tire peripheral driving force acquisition module, configured to brake the vehicle at a second moment using the theoretical wheel cylinder pressure and acquire a target tire peripheral driving force, wherein the target tire peripheral driving force is a critical value applied to the tire periphery to enable the vehicle to move;

[0033] a tire peripheral braking force attenuation value determination module, used for determining the tire peripheral braking force attenuation value according to the difference between the tire peripheral braking force and the target tire peripheral driving force;

[0034] a first attenuation value determination module for wheel cylinder pressure, configured to determine the first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and a mapping relationship between the wheel cylinder pressure and the tire peripheral braking force;

[0035] The target wheel cylinder pressure determination module is used to determine a target wheel cylinder pressure of an automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

[0036] In a third aspect, an embodiment of the present application provides an electronic device, including:

[0037] processor;

[0038] Memory;

[0039] A communication unit, used for establishing a communication channel;

[0040] And a computer program, wherein the computer program is stored in the memory, and the computer program includes instructions, and when the instructions are executed by the processor, the electronic device executes any one of the methods described in the first aspect.

[0041] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the methods described in the first aspect.

[0042] In the embodiment of the present application, the theoretical wheel cylinder pressure at which the vehicle can be parked on the target slope is first determined, and then the theoretical wheel cylinder pressure is compensated according to the attenuation value of the wheel cylinder pressure to obtain the target wheel cylinder pressure of the automatic parking function. When the automatic parking function is activated, the vehicle uses the target wheel cylinder pressure for braking, which can reduce the risk of the vehicle rolling down the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0044] Figure 1 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application.

[0045] Figure 2 A schematic flow chart of a target wheel cylinder pressure calibration method provided in an embodiment of the present application.

[0046] Figure 3 A schematic diagram of vehicle forces provided in an embodiment of the present application.

[0047] Figure 4 A schematic diagram of torque and force provided in an embodiment of the present application.

[0048] Figure 5 Another schematic diagram of vehicle forces provided in an embodiment of the present application.

[0049] Figure 6A schematic flow chart of another target wheel cylinder pressure calibration method provided in an embodiment of the present application.

[0050] Figure 7 A schematic structural diagram of a target wheel cylinder pressure calibration device provided in an embodiment of the present application.

[0051] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0053] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0054] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0055] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0056] The vehicle's automatic parking function can keep the vehicle stopped on flat ground or slopes without the driver having to keep the brake pedal depressed or use the handbrake to keep the vehicle stopped.

[0057] The basic principle of the automatic parking function is: the hydraulic control unit converts the brake pressure received by the brake master cylinder into liquid pressure and transmits it to the wheel cylinder. The piston in the wheel cylinder moves under the liquid pressure, pushing the brake pad to stop the vehicle. For easy understanding, it is explained in detail below with reference to the accompanying drawings.

[0058] See also Figure 1 , is a schematic diagram of the structure of a vehicle provided in an embodiment of the present application. Figure 1As shown, the vehicle includes an electronic stability control system 101, a braking system 102 and a tire 103. The braking system 102 includes a brake master cylinder 1021, a hydraulic control unit 1022 and a wheel cylinder 1023. The brake master cylinder 1021 is used to convert the brake pressure received into liquid pressure, and transmit the liquid pressure to the wheel cylinder 1023 through the hydraulic control unit 1022, so that the wheel cylinder 1023 generates wheel cylinder pressure. Under the action of the wheel cylinder pressure, the braking system generates a tire peripheral braking force that stops the tire 103 from rotating, and keeps the vehicle stopped.

[0059] In addition, a pressure-maintaining valve is configured in the hydraulic control unit 1022. The hydraulic control unit 1022 is used to adjust the pressure-maintaining valve to control the liquid pressure in the hydraulic circuit. When the electronic stability control system 101 detects that the brake pressure reaches the target pressure (usually, when the brake pressure reaches the target pressure, the vehicle can obtain the tire rim braking force required to stop), the hydraulic control unit 1022 in the brake system 102 will close the pressure-maintaining valve, close the hydraulic circuit between the brake master cylinder 1021 and the wheel cylinder 1023, so that the liquid pressure in the wheel cylinder 1023 remains unchanged, and the vehicle is parked.

[0060] However, due to problems such as the production process of the pressure-maintaining valve, the fluid in the hydraulic circuit may leak. It is understandable that fluid leakage in the hydraulic circuit will cause the fluid pressure in the hydraulic circuit to decay. When the automatic parking function is used, due to the decay of the fluid pressure, when the brake pressure reaches the target pressure, the tire rim braking force obtained by the vehicle may not be enough to stop the vehicle, thereby causing the vehicle to slide down the slope.

[0061] In view of the above problem, in the embodiment of the present application, the theoretical wheel cylinder pressure at which the vehicle can be parked on the target slope is first determined, and then the theoretical wheel cylinder pressure is compensated according to the attenuation value of the wheel cylinder pressure to obtain the target wheel cylinder pressure of the automatic parking function. When the automatic parking function is activated, the vehicle uses the target wheel cylinder pressure for braking, which can reduce the risk of the vehicle rolling down the slope. Specifically, it is described in detail below in conjunction with a specific implementation method.

[0062] See also Figure 2 , is a flow chart of a method for calibrating a target wheel cylinder pressure provided in an embodiment of the present application. The method is applied to a vehicle. The vehicle includes a wheel cylinder, which is used to brake the vehicle. Specifically, the method includes the following steps.

[0063] Step S201: At a first moment, obtaining a theoretical wheel cylinder pressure of a wheel cylinder.

[0064] In the embodiment of the present application, the theoretical wheel cylinder pressure is a critical value that allows the vehicle to stop on the target slope. It can be understood that when the actual wheel cylinder pressure of the wheel cylinder is less than the theoretical wheel cylinder pressure, the vehicle cannot stop on the target slope.

[0065] The target ramp may be a ramp with a preset slope of α. For example, the slope may be 15°, 20°, 25°, 30°, etc., and the present application embodiment does not make any specific limitation thereto.

[0066] In order to determine the critical value at which the vehicle can stop on the target slope, in a possible implementation, the automatic parking function can be turned off, and brake pressure is applied to the vehicle so that the vehicle remains stationary on the target slope.

[0067] For easier understanding, see Figure 3 , is a schematic diagram of a vehicle force provided in an embodiment of the present application. Figure 3 As shown, the vehicle is on the target ramp and is subject to the gravity G perpendicular to the target ramp and the braking pressure F parallel to the target ramp. 制动 . Braking pressure F 制动 The direction is A→B, and the braking pressure F 制动 Under the action of the control, the vehicle remains stationary on the target slope.

[0068] In the embodiment of the present application, after applying brake pressure to the vehicle so that the vehicle remains stationary on the target slope, in a possible implementation, the wheel cylinder pressure is controlled to gradually decrease. When the tire (i.e., wheel) movement is detected, the current wheel cylinder pressure of the wheel cylinder is determined to be the theoretical wheel cylinder pressure.

[0069] It can be understood that the braking pressure is applied to the vehicle and the braking pressure is controlled to gradually decrease. When the braking pressure gradually decreases, the wheel cylinder pressure will also gradually decrease. When the tire starts to rotate, the current moment can be determined as the first moment, and the current wheel cylinder pressure of the wheel cylinder can be determined as the theoretical wheel cylinder pressure.

[0070] Step S202: Determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force.

[0071] As described above, under the action of the braking system, the wheel cylinder pressure can be converted into tire peripheral braking force acting on the tire, so that the vehicle stops.

[0072] In a possible implementation, the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force is as follows:

[0073]

[0074] Among them, F b is the braking force around the tire, F is the wheel cylinder pressure, BF is the braking efficiency factor, r is the brake action radius, and R is the tire static radius.

[0075] For easier understanding, see Figure 4, is a schematic diagram of a torque and force provided in an embodiment of the present application. Figure 4 As shown, point O is the rotation axis of the vehicle's brake drum and tire, so the braking torque generated by the brake and the torque that stops the tire from rotating are the same.

[0076] like Figure 4 As shown in (a), the brake includes: a piston, a wheel cylinder, a brake drum, a brake pad and a friction pad. Under the action of the wheel cylinder pressure F, the piston movement can push the brake pad to move to both sides and press the friction pad against the brake drum. At this time, the brake generates a braking torque Tb, that is, F×BF×r. The braking efficiency factor BF can be considered as the braking capacity of the brake. It can be understood that the larger the braking efficiency factor, the stronger the braking capacity of the brake. The brake action radius r refers to the effective action distance from the rotation axis point O to the friction pad during the braking process. It can be understood that when the piston movement pushes the brake pad to move to both sides and presses the friction pad against the brake drum, the brake action radius r is the vertical distance from point O to the brake drum.

[0077] The tire rim braking force is generated under the braking torque of the brake. Figure 4 As shown in (b), under the action of braking torque Tb, a tire peripheral braking force F acting on the tire is generated. b The tire static radius R is the vertical distance between the position of the tire's rotation axis O and the ground under the braking torque.

[0078] In the embodiment of the present application, after the theoretical wheel cylinder pressure that enables the vehicle to stop is obtained, the tire peripheral braking force can be calculated according to the above mapping relationship.

[0079] Exemplarily, the theoretical wheel cylinder pressure is F1, and the tire peripheral braking force is F1×BF×r / R; the theoretical wheel cylinder pressure is F2, and the tire peripheral braking force is F2×BF×r / R; and so on, and the embodiments of the present application are not described in detail here.

[0080] Step S203: At the second moment, the vehicle is braked using the theoretical wheel cylinder pressure, and a target tire peripheral driving force is obtained.

[0081] In the embodiment of the present application, the target tire periphery driving force is a critical value applied to the tire periphery to enable the vehicle to move.

[0082] As described above, the theoretical wheel cylinder pressure is a critical value that allows the vehicle to stop on the target slope, that is, under the effect of the theoretical wheel cylinder pressure, the tire peripheral braking force generated by the brake can stop the vehicle.

[0083] After the vehicle is braked using the theoretical wheel cylinder pressure, the actual wheel cylinder pressure of the wheel cylinder will gradually decay due to the decay of the fluid pressure in the hydraulic circuit. Therefore, the tire circumferential braking force obtained by the vehicle will also gradually decay.

[0084] In order to determine the attenuated tire peripheral braking force, in a possible implementation, a tire peripheral driving force may be applied to the vehicle.

[0085] For easier understanding, see Figure 5 , is another schematic diagram of vehicle stress provided by an embodiment of the present application. Figure 5 As shown in the figure, the vehicle on flat ground is subjected to the gravity G perpendicular to the ground and the tire peripheral braking force F parallel to the ground. 轮制 and the tire rim driving force F 轮驱 Among them, the tire peripheral braking force F 轮制 The tire rim driving force F 轮驱 The direction of the tire rim braking force F 轮制 The direction is B→A, and the tire peripheral driving force is F 轮驱 The direction is A→B.

[0086] In the embodiment of the present application, after applying a tire peripheral driving force in the opposite direction to the attenuated tire peripheral braking force to the vehicle, in a possible implementation, the tire peripheral driving force is controlled to gradually increase. When tire movement is detected, the current tire peripheral driving force is determined to be the target tire peripheral driving force.

[0087] It can be understood that the tire peripheral driving force is controlled to increase gradually. When the applied tire peripheral driving force is equal to the tire peripheral braking force, the vehicle remains stationary. If the tire peripheral driving force continues to increase, when the tire peripheral driving force is greater than the attenuated tire peripheral braking force, the tire will rotate. Therefore, when the tire movement is detected, the current tire peripheral driving force can be determined to be the target tire peripheral driving force (i.e., the attenuated tire peripheral braking force), and the current moment can be determined to be the second moment.

[0088] Step S204: Determine the attenuation value of the tire peripheral braking force according to the difference between the tire peripheral braking force and the target tire peripheral driving force.

[0089] In the embodiment of the present application, the tire peripheral braking force (i.e., the tire peripheral braking force corresponding to the theoretical wheel cylinder pressure) is first obtained; then the attenuated tire peripheral braking force (i.e., the target tire peripheral driving force) is obtained; finally, the tire peripheral braking force is subtracted from the target tire peripheral driving force, so that the attenuation value of the tire peripheral braking force can be quickly determined.

[0090] Step S205: determining a first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and a mapping relationship between the wheel cylinder pressure and the tire peripheral braking force.

[0091] The first attenuation value of the wheel cylinder pressure may be considered to be a attenuation value of the wheel cylinder pressure during a period from the first time to the second time.

[0092] After the attenuation value of the tire peripheral braking force is determined, the first attenuation value of the wheel cylinder pressure can be determined according to the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force as described above.

[0093] Exemplarily, the attenuation value of the tire peripheral braking force is N1, and the first attenuation value of the wheel cylinder pressure is N1×R / (BF×r); the attenuation value of the tire peripheral braking force is N2, and the first attenuation value of the wheel cylinder pressure is N2×R / (BF×r); and so on, and the embodiments of the present application are not described in detail here.

[0094] Step S206: Determine a target wheel cylinder pressure for the automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

[0095] The target wheel cylinder pressure of the automatic parking function is the wheel cylinder pressure after the theoretical wheel cylinder pressure is compensated by the attenuation value of the wheel cylinder pressure, so that the vehicle can remain stationary at the target wheel cylinder pressure.

[0096] In the embodiment of the present application, the theoretical wheel cylinder pressure is first obtained; then the first attenuation value of the wheel cylinder pressure is obtained; finally, the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure are added, so that the target wheel cylinder pressure at the first time length can be quickly determined.

[0097] In a possible implementation, after the target wheel cylinder pressure of the automatic parking function is determined, the target wheel cylinder pressure may be corrected according to the release coefficient of the automatic parking function.

[0098] The automatic parking function release coefficient can be considered as the ability and efficiency of the automatic parking function to release the brakes when the vehicle starts.

[0099] That is, by correcting the target wheel cylinder pressure according to the automatic parking function release coefficient, the automatic parking function can be easily released while ensuring that the vehicle has no risk of rolling down a slope, that is, the vehicle can be easily started.

[0100] In the embodiment of the present application, the target wheel cylinder pressure required for the vehicle to maintain a stationary state from the first moment to the second moment (i.e., the wheel cylinder pressure after the theoretical wheel cylinder pressure is compensated by the first attenuation value of the wheel cylinder pressure) can be determined according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure. When the automatic parking function is activated, the vehicle is braked using the target wheel cylinder pressure corresponding to the first duration, which can reduce the risk of the vehicle rolling down the slope from the first moment to the second moment.

[0101] However, in actual applications, it may be necessary to compensate the theoretical wheel cylinder pressure according to the attenuation values ​​of the wheel cylinder pressure at different time lengths to determine the target wheel cylinder pressure required for the vehicle to remain stationary at different attenuation values ​​of the wheel cylinder pressure.

[0102] For easier understanding, see Figure 6 , is a flow chart of another target wheel cylinder pressure calibration method provided in an embodiment of the present application. Figure 6 As shown, this method Figure 2 On the basis of, step S206 specifically includes the following steps.

[0103] Step S2061: Determine the attenuation rate of the wheel cylinder pressure according to the first attenuation value and the first duration of the wheel cylinder pressure.

[0104] The first time length is the time length from the first moment to the second moment. In the embodiment of the present application, the first attenuation value of the wheel cylinder pressure is first determined; then the first time length is determined; finally, the first attenuation value of the wheel cylinder pressure and the first time length can be divided to quickly and accurately calculate the attenuation rate of the wheel cylinder pressure.

[0105] Exemplarily, the first attenuation value of the wheel cylinder pressure is N11, the first time length is T11, and the attenuation rate of the wheel cylinder pressure is N11 / T11; the first attenuation value of the wheel cylinder pressure is N12, the first time length is T12, and the attenuation rate of the wheel cylinder pressure is N12 / T12; and so on, which will not be repeated in this application.

[0106] However, if no braking pressure is applied to the vehicle during a certain period between the first moment and the second moment, the decay value of the wheel cylinder pressure during this period may be zero, resulting in inaccurate decay rate determined at the first time length.

[0107] Therefore, in a possible implementation, the vehicle maintains a braking state during the period from the first moment to the second moment. It is understandable that during the period from the first moment to the second moment, braking pressure may be continuously applied to the vehicle to ensure that the wheel cylinder pressure during the period from the first moment to the second moment continuously decays.

[0108] It should be noted that the same brake pressure needs to be applied to the vehicle during the period from the first moment to the second moment. It is understandable that when different brake pressures are applied to the vehicle during the first time period and the second time period during the period from the first moment to the second moment, the leakage speed of the liquid in the liquid circuit during the first time period and the second time period is different, which may cause a deviation in the calculated decay rate of the wheel cylinder pressure.

[0109] In a possible implementation, the vehicle maintains a braking state at the theoretical wheel cylinder pressure during the period from the first moment to the second moment. In other words, during the period from the first moment to the second moment, a braking pressure corresponding to the theoretical wheel cylinder pressure is applied to the vehicle, so that the leakage rate of the liquid in the liquid circuit during the period from the first moment to the second moment can be the same, and a more accurate attenuation rate of the wheel cylinder pressure can be obtained.

[0110] Step S2062: Determine a second attenuation value of the wheel cylinder pressure according to the attenuation rate of the wheel cylinder pressure and the second time duration.

[0111] In the embodiment of the present application, the second time period is the time period from the first moment to the current moment. The second attenuation value of the wheel cylinder pressure can be considered as the attenuation value of the wheel cylinder pressure from the first moment to the current moment.

[0112] In a possible implementation, the decay rate of the wheel cylinder pressure may be multiplied by the second time duration to quickly and accurately calculate the second decay value of the wheel cylinder pressure.

[0113] Exemplarily, the attenuation rate of the wheel cylinder pressure is K1, the second time duration is T21, and the second attenuation value of the wheel cylinder pressure is K1×T21; the attenuation rate of the wheel cylinder pressure is K2, the second time duration is T22, and the second attenuation value of the wheel cylinder pressure is K2×T22; and so on, which will not be repeated in this application.

[0114] Step S2063: Determine the target wheel cylinder pressure of the automatic parking function according to the second attenuation value of the wheel cylinder pressure and the theoretical wheel cylinder pressure.

[0115] In the embodiment of the present application, the second attenuation value of the wheel cylinder pressure is first obtained; then the theoretical wheel cylinder pressure is obtained; finally, the second attenuation value of the wheel cylinder pressure is added to the theoretical wheel cylinder pressure, so that the target wheel cylinder pressure at the second time length can be quickly determined.

[0116] It can be understood that the target wheel cylinder pressure required for the vehicle to maintain a stationary state from the first moment to the current moment (i.e., the wheel cylinder pressure after the second attenuation value of the wheel cylinder pressure compensates the theoretical wheel cylinder pressure) can be determined based on the second attenuation value of the wheel cylinder pressure and the theoretical wheel cylinder pressure. When the automatic parking function is activated, the vehicle is braked using the target wheel cylinder pressure corresponding to the second duration, which can reduce the risk of the vehicle rolling down a slope from the first moment to the current moment.

[0117] In the embodiment of the present application, the theoretical wheel cylinder pressure at which the vehicle can be parked on the target slope is first determined, and then the theoretical wheel cylinder pressure is compensated according to the attenuation value of the wheel cylinder pressure to obtain the target wheel cylinder pressure of the automatic parking function. When the automatic parking function is activated, the vehicle uses the target wheel cylinder pressure for braking, which can reduce the risk of the vehicle rolling down the slope.

[0118] Corresponding to the above method embodiment, the present application also provides a target wheel cylinder pressure calibration device for an automatic parking function. Figure 7 , is a schematic diagram of the structure of a target wheel cylinder pressure calibration device provided in an embodiment of the present application. Figure 7 As shown, the target wheel cylinder pressure calibration device 300 is applied to a vehicle, the vehicle includes a wheel cylinder, and the wheel cylinder is used to brake the vehicle, including: a theoretical wheel cylinder pressure acquisition module 301, a tire peripheral braking force determination module 302, a target tire peripheral driving force acquisition module 303, a tire peripheral braking force attenuation value determination module 304, a first attenuation value determination module 305 of the wheel cylinder pressure and a target wheel cylinder pressure determination module 306.

[0119] Specifically, the theoretical wheel cylinder pressure acquisition module 301 is used to acquire the theoretical wheel cylinder pressure of the wheel cylinder at the first moment, and the theoretical wheel cylinder pressure is a critical value that allows the vehicle to stop on the target slope; the tire peripheral braking force determination module 302 is used to determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; the target tire peripheral driving force acquisition module 303 is used to brake the vehicle at the second moment using the theoretical wheel cylinder pressure and acquire the target tire peripheral driving force, and the target tire peripheral driving force is the pressure applied to the tire periphery. , which is a critical value that allows the vehicle to move; a tire peripheral braking force attenuation value determination module 304, which is used to determine the attenuation value of the tire peripheral braking force according to the difference between the tire peripheral braking force and the target tire peripheral driving force; a wheel cylinder pressure first attenuation value determination module 305, which is used to determine the first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; a target wheel cylinder pressure determination module 306, which is used to determine the target wheel cylinder pressure of the automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

[0120] The specific contents involved in the embodiments of the present application can be found in the description of the above method embodiments. For the sake of brevity, they will not be elaborated on here.

[0121] Corresponding to the above method embodiments, the present application also provides an electronic device, which is configured to execute the above method embodiments.

[0122] See also Figure 8, is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 8 As shown, the electronic device 400 may include: a processor 401, a memory 402 and a communication unit 403. These components communicate via one or more buses. Those skilled in the art will appreciate that the structure of the electronic device shown in the figure does not limit the embodiments of the present application, and it may be a bus structure or a star structure, and may include more or fewer components than shown in the figure, or combine certain components, or arrange components differently.

[0123] The communication unit 403 is used to establish a communication channel so that the electronic device can communicate with other devices, receive user data sent by other devices or send user data to other devices.

[0124] The processor 401 is the control center of the electronic device. It uses various interfaces and lines to connect various parts of the entire electronic device. It runs or executes software programs, instructions, and / or modules stored in the memory 402, and calls data stored in the memory to perform various functions of the electronic device and / or process data. The processor can be composed of an integrated circuit (IC), for example, it can be composed of a single packaged IC, or it can be composed of multiple packaged ICs with the same or different functions. For example, the processor 401 can include only a central processing unit (CPU). In the embodiment of the present application, the CPU can be a single computing core or multiple computing cores.

[0125] Memory 402 is used to store execution instructions of processor 401. Memory 402 can be implemented by any type of volatile or non-volatile storage device or a combination of them, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0126] When the execution instruction in the memory 402 is executed by the processor 401, the electronic device 400 can execute Figure 2 Some or all of the steps in the illustrated embodiments.

[0127] The specific contents involved in the embodiments of the present application can be found in the description of the above method embodiments. For the sake of brevity, they will not be elaborated on here.

[0128] Corresponding to the above embodiment, the embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium may store a program, wherein when the program is running, the device where the computer-readable storage medium is located may be controlled to perform some or all of the steps in the above method embodiment. In a specific implementation, the computer-readable storage medium may be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM).

[0129] Corresponding to the above-mentioned embodiment, the embodiment of the present application further provides a computer program product, which includes executable instructions. When the executable instructions are executed on a computer, the computer executes some or all of the steps in the above-mentioned method embodiment.

[0130] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0131] Those of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0132] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0133] In several embodiments provided in the present application, any function can be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as an independent product. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., and other media that can store program codes.

[0134] The above is only a specific implementation of the present application. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for calibrating target wheel cylinder pressure of an automatic parking function, characterized in that: Applied to a vehicle, the vehicle includes a wheel cylinder, the wheel cylinder is used to brake the vehicle, the method includes: At a first moment, obtaining a theoretical wheel cylinder pressure of the wheel cylinder, wherein the theoretical wheel cylinder pressure is a critical value for enabling the vehicle to stop on a target slope; Determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; At a second moment, the vehicle is braked using the theoretical wheel cylinder pressure, and a target tire peripheral driving force is obtained, where the target tire peripheral driving force is a critical value applied to the tire periphery to allow the vehicle to move; determining an attenuation value of the tire peripheral braking force according to a difference between the tire peripheral braking force and the target tire peripheral driving force; Determining a first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and a mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; A target wheel cylinder pressure for an automatic parking function is determined based on the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

2. The method according to claim 1, characterized in that During the period from the first moment to the second moment, the vehicle maintains a braking state.

3. The method according to claim 2, characterized in that During the period from the first time to the second time, the vehicle maintains a braking state at the theoretical wheel cylinder pressure.

4. The method according to claim 2 or 3, characterized in that: The step of determining a target wheel cylinder pressure for an automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure comprises: determining a decay rate of the wheel cylinder pressure according to a first decay value and a first time duration of the wheel cylinder pressure, wherein the first time duration is a time duration from the first moment to the second moment; determining a second attenuation value of the wheel cylinder pressure according to the attenuation rate of the wheel cylinder pressure and a second time period, wherein the second time period is a time period from the first moment to the current moment; A target wheel cylinder pressure for an automatic parking function is determined based on the second attenuation value of the wheel cylinder pressure and the theoretical wheel cylinder pressure.

5. The method according to claim 1, characterized in that The mapping relationship between the wheel cylinder pressure and the tire peripheral braking force is as follows: Among them, F b is the braking force around the tire, F is the wheel cylinder pressure, BF is the braking efficiency factor, r is the brake action radius, and R is the tire static radius.

6. The method according to claim 1, characterized in that The obtaining of the theoretical wheel cylinder pressure of the wheel cylinder comprises: On the target slope, the automatic parking function is turned off, and the wheel cylinder pressure is controlled to be gradually reduced until the wheel movement is detected, and the current wheel cylinder pressure of the wheel cylinder is determined to be the theoretical wheel cylinder pressure.

7. The method according to claim 1, characterized in that The step of obtaining the target tire peripheral driving force comprises: The tire peripheral driving force is controlled to gradually increase until the wheel movement is detected, and the current tire peripheral driving force is determined to be the target tire peripheral driving force.

8. A target wheel cylinder pressure calibration device for an automatic parking function, characterized in that: Applied to a vehicle, the vehicle comprises a wheel cylinder, the wheel cylinder is used to brake the vehicle, the device comprises: a theoretical wheel cylinder pressure acquisition module, configured to acquire a theoretical wheel cylinder pressure of the wheel cylinder at a first moment, wherein the theoretical wheel cylinder pressure is a critical value for enabling the vehicle to stop on a target slope; A tire peripheral braking force determination module, used to determine the tire peripheral braking force according to the theoretical wheel cylinder pressure and the mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; a target tire peripheral driving force acquisition module, configured to brake the vehicle at a second moment using the theoretical wheel cylinder pressure and acquire a target tire peripheral driving force, wherein the target tire peripheral driving force is a critical value applied to the tire periphery to enable the vehicle to move; a tire peripheral braking force attenuation value determination module, used for determining the tire peripheral braking force attenuation value according to the difference between the tire peripheral braking force and the target tire peripheral driving force; a first attenuation value determination module for wheel cylinder pressure, configured to determine the first attenuation value of the wheel cylinder pressure according to the attenuation value of the tire peripheral braking force and a mapping relationship between the wheel cylinder pressure and the tire peripheral braking force; The target wheel cylinder pressure determination module is used to determine a target wheel cylinder pressure of an automatic parking function according to the theoretical wheel cylinder pressure and the first attenuation value of the wheel cylinder pressure.

9. An electronic device, characterized in that: include: processor; Memory; A communication unit, used for establishing a communication channel; And a computer program, wherein the computer program is stored in the memory, and the computer program includes instructions, and when the instructions are executed by the processor, the electronic device executes the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method according to any one of claims 1 to 7.

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