Friction plate modeling method of brake system and related device

Abstract

The invention discloses a friction plate modeling method of a braking system and a related device, and relates to the technical field of vehicle dynamics, the first braking state of the braking system at the current moment is determined; and under the condition that the first braking state is the locked state, based on the assumption that the connection relation is the spring damping system, the first friction torque between the friction plate model and the wheel model is calculated, and the first friction torque is the first braking torque of the braking system in the locked state. When the wheel is locked, the static friction force of the friction plate is approximately equal to the rolling resistance of the wheel, and the friction plate and the wheel are not absolutely rigid, so that the friction plate slightly deforms under stress, and the static friction force of the friction plate fluctuates up and down under the resistance of the wheel but does not suddenly change; according to the application, during modeling, a spring damping system is used between the friction plate model and the wheel model to achieve a similar effect, so that the brake torque under a vehicle locking state can be accurately simulated, and great help can be provided for a brake control system algorithm simulation test.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle dynamics, and in particular to a friction plate modeling method and related devices for a braking system. Background Art

[0002] At present, the friction plate modeling method of the vehicle braking system generally calculates the friction torque (often referred to as braking torque) between the friction plate model and the wheel model through empirical formulas or test data lookup tables.

[0003] The above method is only applicable when the wheel model is not locked. This is because the friction plate model and the wheel model are in a sliding state at this time, and there is dynamic friction between the two, so the braking torque can be approximately simulated. Once the wheel model is locked, there is no relative sliding between the friction plate model and the wheel model, so the braking torque cannot be accurately simulated. Summary of the invention

[0004] In view of the above problems, the present application provides a friction plate modeling method and related devices for a brake system to achieve the purpose of accurately simulating the braking torque under different braking conditions. The specific scheme is as follows:

[0005] A first aspect of the present application provides a friction plate modeling method for a brake system, the friction plate modeling method for a brake system comprising:

[0006] Determine a first braking state of the braking system at a current moment;

[0007] When the first braking state is a locked state, a first friction torque between the friction plate model and the wheel model is calculated based on the assumption that the connection relationship is a spring damping system, and the first friction torque is the first braking torque of the braking system in the locked state.

[0008] In a possible implementation, the friction plate modeling method of the brake system further includes:

[0009] When the first braking state is a sliding state, obtaining a first friction plate temperature of the friction plate model at a current moment and a first wheel cylinder pressure of the braking system at a current moment;

[0010] A second friction torque between the friction plate model and the wheel model is calculated according to the first friction plate temperature and the first wheel cylinder pressure, where the second friction torque is a second braking torque of the brake system in a slip state.

[0011] In a possible implementation, determining the first braking state of the braking system at a current moment includes:

[0012] Retrieving the second braking state of the braking system at the last moment;

[0013] When the second braking state is empty or the second braking state is a slipping state, determining an equivalent wheel speed of the wheel model at a current moment;

[0014] Determining whether the equivalent wheel speed is zero;

[0015] If so, determining that the first braking state is a locking state;

[0016] If not, it is determined that the first braking state is a sliding wear state.

[0017] In a possible implementation, determining the equivalent wheel speed of the wheel model at the current moment includes:

[0018] Obtaining a first wheel speed of the wheel model at a previous moment and a second wheel speed at a current moment;

[0019] calculating the product of the first wheel speed and the second wheel speed;

[0020] When the product is greater than zero, determining the equivalent wheel speed to be the second wheel speed;

[0021] When the product is less than or equal to zero, the equivalent wheel speed is determined to be zero.

[0022] In a possible implementation, determining the first braking state of the braking system at the current moment further includes:

[0023] When the second braking state is a locking state, obtaining a third braking torque of the braking system at a previous moment;

[0024] Acquire a second friction plate temperature of the friction plate model at the current moment and a second wheel cylinder pressure of the brake system at the current moment;

[0025] calculating the maximum static friction force between the friction plate model and the wheel model according to the second friction plate temperature and the second wheel cylinder pressure;

[0026] When the third braking torque is greater than the maximum static friction force, determining that the first braking state is a sliding friction state;

[0027] When the third braking torque is less than or equal to the maximum static friction force, it is determined that the first braking state is a locking state.

[0028] In a possible implementation, the calculating the first friction torque between the friction plate model and the wheel model based on the assumption that the connection relationship is a spring damping system includes:

[0029] Obtaining the driving torque, road load torque and wheel rotational inertia of the wheel model at the current moment;

[0030] constructing a first expression for characterizing the angular acceleration of the wheel model relative to the friction plate model according to the driving torque, the road load torque, the wheel moment of inertia and the first friction torque;

[0031] By performing an integration operation on the first expression, a second expression for characterizing the angular velocity of the wheel model relative to the friction plate model is constructed;

[0032] Determine the equivalent spring stiffness and equivalent damping coefficient;

[0033] Acquire a fourth braking torque of the braking system in a last slipping state, and calculate a ratio of the fourth braking torque to the equivalent spring stiffness;

[0034] By integrating the second expression and superimposing it with the ratio, a third expression for characterizing the angle of the wheel model relative to the friction plate model is constructed;

[0035] Using the equivalent spring stiffness and the third expression, construct a fourth expression for characterizing the spring torque;

[0036] Using the equivalent damping coefficient and the second expression, construct a fifth expression for characterizing the damping torque;

[0037] The first friction torque is set equal to the sum of the spring torque and the damping torque, and the fourth expression and the fifth expression are solved to obtain the first friction torque.

[0038] A second aspect of the present application provides a friction plate modeling device for a brake system, the friction plate modeling device for a brake system comprising:

[0039] A determination module, used to determine a first braking state of the braking system at a current moment;

[0040] A calculation module is used to calculate a first friction torque between a friction plate model and a wheel model when the first braking state is a locked state based on the assumption that the connection relationship is a spring damping system, wherein the first friction torque is a first braking torque of the braking system in a locked state.

[0041] A third aspect of the present application provides a computer program product, comprising computer-readable instructions, which, when executed on an electronic device, enables the electronic device to implement the friction plate modeling method for a brake system according to the first aspect or any implementation of the first aspect.

[0042] A fourth aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0043] The memory is used to store computer programs;

[0044] The processor is used to execute the computer program so that the electronic device can implement the friction plate modeling method of the brake system according to the above-mentioned first aspect or any implementation method of the first aspect.

[0045] The fifth aspect of the present application provides a computer storage medium, which carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement the friction plate modeling method of the brake system of the above-mentioned first aspect or any implementation method of the first aspect.

[0046] By means of the above technical solution, the present application provides a friction plate modeling method and related devices for a braking system, which determine the first braking state of the braking system at the current moment; when the first braking state is a locked state, based on the assumption that the connection relationship is a spring damping system, the first friction torque between the friction plate model and the wheel model is calculated, and the first friction torque is the first braking torque of the braking system in the locked state. When the wheel is locked, the static friction force of the friction plate is approximately equal to the rolling resistance of the wheel. Since the friction plate and the wheel are not absolutely rigid and will be slightly deformed by force, the static friction force of the friction plate will fluctuate up and down due to the wheel resistance, but will not change suddenly. For this reason, the present application uses a spring damping system between the friction plate model and the wheel model during modeling to achieve a similar effect, so that the braking torque of the vehicle in the locked state can be accurately simulated, which can provide great help for the simulation test of the braking control system algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0048] Figure 1 A schematic diagram of a flow chart of a friction plate modeling method for a brake system provided in an embodiment of the present application;

[0049] Figure 2 This is an equivalent schematic diagram of the connection relationship between the friction plate model and the wheel model in a locked state in an embodiment of the present application;

[0050] Figure 3A partial flow chart of a friction plate modeling method for a brake system provided in an embodiment of the present application;

[0051] Figure 4 Another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application;

[0052] Figure 5 Another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application;

[0053] Figure 6 Another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application;

[0054] Figure 7 A schematic diagram of the structure of a friction plate modeling device for a brake system provided in an embodiment of the present application;

[0055] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0056] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0057] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0058] The terms "first", "second" etc. in the specification of the application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable in appropriate circumstances, and this is only to describe the distinction mode adopted by the objects of the same attributes when describing in the embodiments of the application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0059] The existing friction plate modeling method of the vehicle brake system generally calculates the braking torque between the friction plate model and the wheel model by using an empirical formula or a test data table lookup method, as shown in the following formula (1):

[0060] T brk1 =f1(T,p) (1)

[0061] Among them, T brk1 is the friction torque between the friction plate model and the wheel model (i.e., braking torque), T is the friction plate temperature of the friction plate model, and p is the wheel cylinder pressure of the braking system.

[0062] When the wheel model is not locked, the friction plate model and the wheel model are in a sliding state, and there is dynamic friction between the two. The above formula (1) can approximately simulate the braking torque. When the wheel model is locked, there is no relative sliding between the friction plate model and the wheel model, and the above formula (1) cannot accurately simulate the braking torque.

[0063] In order to solve the above problems, the embodiment of the present application provides a friction plate modeling method and related devices for a brake system, which can calculate the braking torque between the friction plate model and the wheel model under different braking states. The friction plate modeling method for a brake system in the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0064] See also Figure 1 , Figure 1 The following is a flow chart of a friction plate modeling method for a brake system provided in an embodiment of the present application. Figure 1 As shown, a friction plate modeling method for a brake system provided in an embodiment of the present application may include steps S10 to S20, and these steps are described in detail below.

[0065] S10, determining a first braking state of the braking system at a current moment.

[0066] In the embodiment of the present application, during the simulation modeling process, different moments for calculating the braking torque can be determined according to the simulation step length. For this, at each moment, the braking state of the braking system at the current moment, i.e., the first braking state, is determined. The first braking state can be divided into a locking state and a sliding state, i.e., determining whether the friction plate model and the wheel model are in a locking state or a sliding state at the current moment.

[0067] In this regard, it can be divided into a simulation start stage and a simulation ongoing stage. In the simulation start stage, if the wheel speed at the current moment is not equal to zero, it can be determined that the first braking state is a sliding state. On the contrary, if the wheel speed at the current moment is equal to zero, it can be determined that the first braking state is a locking state. In the simulation ongoing stage, it can be determined in combination with the braking state of the previous moment. Specifically, if the previous moment was a sliding state and the wheel speed at the current moment is equal to zero, the first braking state is determined to be a locking state. On the contrary, if the previous moment was a locking state and the braking torque at the previous moment was greater than the maximum static friction between the friction plate model and the wheel model, the first braking state is determined to be a sliding state.

[0068] S20, when the first braking state is a locked state, based on the assumption that the connection relationship is a spring damping system, calculate the first friction torque between the friction plate model and the wheel model, the first friction torque being the first braking torque of the braking system in the locked state.

[0069] When the wheel is locked, the static friction of the friction plate is approximately equal to the rolling resistance of the wheel. Since the friction plate and the wheel are not absolutely rigid and will deform slightly when subjected to force, the static friction of the friction plate will fluctuate up and down due to the wheel resistance, but will not change suddenly. In this regard, the present application uses a spring damping system between the friction plate model and the wheel model to achieve a similar effect when modeling. Figure 2 , Figure 2 FIG. 1 is an equivalent schematic diagram of the connection relationship between the friction plate model and the wheel model in a locked state in an embodiment of the present application. Figure 2 As shown, in an embodiment of the present application, when the first braking state is a locked state, it can be assumed that the connection relationship between the friction plate model and the wheel model is a spring damping system, so as to calculate the friction torque between the friction plate model and the wheel model (i.e., the first friction torque), and the first friction torque is used as the braking torque of the braking system in the locked state at the current moment (i.e., the first braking torque).

[0070] In steady state, the static friction of the friction plate and the rolling resistance of the wheel work together to produce a fixed angle difference between the friction plate and the wheel. The product of the angle difference and the spring stiffness is exactly equal to the static friction of the friction plate (or the rolling resistance of the wheel). The damping is used to stabilize the system. Since the damping is very small, the impact on the accuracy is also very small and can be ignored. The spring damping system can make the static friction of the friction plate smooth and continuous, avoid sudden changes, and enhance the stability of the model. It should be noted that in the embodiment of the present application, the spring and damping are real components. It is only an equivalent assumption that the connection relationship between the friction plate model and the wheel model is made, and the braking torque at this time is assumed to be the combined force of the spring torque and the damping torque.

[0071] On this basis, when the first braking state is a sliding state, the existing method can be used to calculate the braking torque at this time. In this regard, a friction plate modeling method for a braking system provided in an embodiment of the present application also includes the following steps:

[0072] When the first braking state is a slipping state, the first friction plate temperature of the friction plate model at the current moment and the first wheel cylinder pressure of the braking system at the current moment are obtained; the second friction torque between the friction plate model and the wheel model is calculated according to the first friction plate temperature and the first wheel cylinder pressure, and the second friction torque is the second braking torque of the braking system in the slipping state.

[0073] In the embodiment of the present application, when the first braking state is the sliding state, the friction plate temperature of the friction plate model at the current moment (i.e., the first friction plate temperature) and the wheel cylinder pressure of the brake system at the current moment (i.e., the first wheel cylinder pressure) are obtained. The first friction plate temperature is output by the friction plate model, and the first wheel cylinder pressure is output by the brake system and is related to the brake pedal, the master cylinder pressure, the vehicle controller, etc.

[0074] Furthermore, the second friction torque between the friction plate model and the wheel model is calculated according to the first friction plate temperature and the first wheel cylinder pressure, as shown in the following formula (2):

[0075] T1 static_friction =f2(T1,p1) (2)

[0076] Among them, T1 static_friction is the second friction torque, T1 is the first friction plate temperature, and p1 is the first wheel cylinder pressure. The second friction torque is the braking torque (ie, the second braking torque) of the braking system in the slip state at the current moment.

[0077] However, in the discrete solution process of actual simulation, there may not be a moment when the wheel speed is equal to zero according to the simulation step size. For example, under the wheel deceleration condition, the wheel speed at the previous moment may be positive and the wheel speed at the next moment may be negative. In this regard, in the embodiment of the present application, the equivalent wheel speed at the current moment can be determined according to the change direction of the wheel speed at the previous moment and the wheel speed at the current moment.

[0078] See also Figure 3 , Figure 3 This is a partial flow chart of a friction plate modeling method for a brake system provided in an embodiment of the present application. Figure 3 As shown, an embodiment of the present application provides a friction plate modeling method for a braking system, wherein step S10 "determines the first braking state of the braking system at the current moment" may include the following steps S101 to S105, which are described in detail below.

[0079] S101, retrieve the second braking state of the braking system at the last moment.

[0080] In the embodiment of the present application, the braking state of the braking system at the last moment is retrieved, that is, the second braking state. At the beginning of the simulation, the second braking state is empty; during the simulation, the second braking state is a locking state or a sliding state.

[0081] S102, when the second braking state is empty or the second braking state is a slipping state, determine the equivalent wheel speed of the wheel model at the current moment.

[0082] In the embodiment of the present application, when the second braking state is empty or the second braking state is a slipping state, the equivalent wheel speed at the current moment can be determined according to the wheel speed of the wheel model at the previous moment and the wheel speed at the current moment. Specifically, if the wheel speed at the previous moment is greater than zero and the wheel speed at the current moment is less than zero, or the wheel speed at the previous moment is less than zero and the wheel speed at the current moment is greater than zero, or one of the wheel speed at the previous moment and the wheel speed at the current moment is equal to zero, then the equivalent wheel speed is determined to be zero, otherwise, then the equivalent wheel speed is determined to be non-zero.

[0083] See also Figure 4 , Figure 4 This is another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application. Figure 4 As shown, an embodiment of the present application provides a friction plate modeling method for a braking system, wherein "determining the equivalent wheel speed of the wheel model at the current moment" in step S102 may include the following steps S1021 to S1024, and these steps are described in detail below.

[0084] S1021, obtaining the first wheel speed of the wheel model at the previous moment and the second wheel speed at the current moment.

[0085] S1022, calculating the product of the first wheel speed and the second wheel speed.

[0086] S1023: When the product is greater than zero, determine the equivalent wheel speed as the second wheel speed.

[0087] S1024: When the product is less than or equal to zero, determine that the equivalent wheel speed is zero.

[0088] In the embodiment of the present application, the wheel speed is output by the wheel model, and the wheel speed of the wheel model at different times can be collected, including the wheel speed of the wheel model at the previous moment (i.e., the first wheel speed) and the wheel speed at the current moment (i.e., the second wheel speed). Further, the product of the first wheel speed and the second wheel speed is calculated. If the product is greater than zero, that is, the first wheel speed and the second wheel speed are both positive or negative, the second wheel speed is used as the equivalent wheel speed. Otherwise, if the product is less than or equal to zero, the equivalent wheel speed is determined to be zero.

[0089] S103, determine whether the equivalent wheel speed is zero; if so, execute step S104; if not, execute step S105.

[0090] S104: Determine that the first braking state is a locking state.

[0091] S105, determining that the first braking state is a sliding wear state.

[0092] In the embodiment of the present application, if the equivalent wheel speed is equal to zero, the first braking state is determined to be a locked state. Specifically, at the beginning of the simulation, that is, when the simulation modeling starts, the friction plate model and the wheel model are in a locked state, and during the simulation stage, the friction plate model and the wheel model are switched from a sliding state to a locked state.

[0093] In addition, if the equivalent wheel speed is not equal to zero, the first braking state is determined to be a sliding state. Specifically, at the beginning of the simulation, that is, when the simulation modeling starts, the friction plate model and the wheel model are in a sliding state, and during the simulation stage, the friction plate model and the wheel model are continuously in a sliding state.

[0094] On this basis, if the second braking state is a locking state, the maximum static friction between the friction plate model and the wheel model can be used to determine whether the sliding state has been entered. Figure 5 , Figure 5 This is another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application. Figure 5 As shown, an embodiment of the present application provides a friction plate modeling method for a braking system, wherein step S10 "determines the first braking state of the braking system at the current moment" may also include the following steps S106 to S110, which are described in detail below.

[0095] S106, when the second braking state is a locking state, obtaining a third braking torque of the braking system at a previous moment.

[0096] S107, obtaining a second friction plate temperature of the friction plate model at the current moment, and a second wheel cylinder pressure of the brake system at the current moment.

[0097] S108, calculating the maximum static friction force between the friction plate model and the wheel model according to the second friction plate temperature and the second wheel cylinder pressure.

[0098] S109: When the third braking torque is greater than the maximum static friction force, determining that the first braking state is a sliding friction state.

[0099] S110: When the third braking torque is less than or equal to the maximum static friction force, determine that the first braking state is a locking state.

[0100] In the embodiment of the present application, when the second braking state is a locked state, the braking torque (i.e., the third braking torque) of the braking system in the locked state at the previous moment is obtained. In addition, the friction plate temperature (i.e., the second friction plate temperature) of the friction plate model at the current moment and the wheel cylinder pressure (i.e., the second wheel cylinder pressure) of the braking system at the current moment are obtained. The second friction plate temperature is output by the friction plate model, and the second wheel cylinder pressure is output by the braking system and is related to the brake pedal, the master cylinder pressure, the vehicle-mounted controller, etc.

[0101] Furthermore, the maximum static friction force between the friction plate model and the wheel model is calculated according to the second friction plate temperature and the second wheel cylinder pressure, as shown in the following formula (3):

[0102] T static_friction =f2(T2,p2) (3)

[0103] Among them, T static_friction is the maximum static friction force, T2 is the second friction plate temperature, and p2 is the second wheel cylinder pressure.

[0104] Further, the third braking torque is compared with the maximum static friction force. If the third braking torque is greater than the maximum static friction force, it means that the braking system enters the sliding state from the locked state, that is, the first braking state is the sliding state, and conversely, if the third braking torque is less than or equal to the maximum static friction force, it means that the braking system is continuously in the locked state, that is, the first braking state is the locked state.

[0105] See also Figure 6 , Figure 6 This is another partial flow chart of a method for modeling a friction plate of a brake system provided in an embodiment of the present application. Figure 6 As shown, an embodiment of the present application provides a friction plate modeling method for a braking system, wherein step S20 "calculates the first friction torque between the friction plate model and the wheel model based on the assumption that the connection relationship is a spring damping system" may include the following steps S201 to S209, which are described in detail below.

[0106] S201, obtaining the driving torque, road load torque and wheel rotational inertia of the wheel model at the current moment.

[0107] In the embodiment of the present application, the driving torque refers to the driving torque received by the wheel model, which is output by the drive system; the road load torque refers to the road load torque received by the wheel model, which is output by the wheel model; and the wheel rotational inertia is related to the wheel model.

[0108] S202: construct a first expression for characterizing the angular acceleration of the wheel model relative to the friction plate model according to the driving torque, the road load torque, the wheel rotational inertia and the first friction torque.

[0109] In the embodiment of the present application, for the angular acceleration of the wheel model relative to the friction plate model, a corresponding expression (i.e., a first expression) can be constructed based on Newton's second law. The first expression is shown in the following formula (4):

[0110] whl_acc=(T brk1 +T dri +T load ) / J whl (4)

[0111] Where whl_acc is the angular acceleration, T brk1 is the first friction torque, T dri is the driving torque, T load is the road load torque, J whl is the wheel moment of inertia.

[0112] S203: construct a second expression for characterizing the angular velocity of the wheel model relative to the friction plate model by performing an integration operation on the first expression.

[0113] In the embodiment of the present application, for the angular velocity of the wheel model relative to the friction plate model, a corresponding expression (i.e., a second expression) is constructed. The second expression is shown in the following formula (5), where the integration start time is the time when the brake system starts to enter the locked state this time:

[0114] whl_spd=∫whl_acc (5)

[0115] Where whl_spd is the angular velocity.

[0116] S204, determining an equivalent spring stiffness and an equivalent damping coefficient.

[0117] In the embodiment of the present application, the equivalent spring stiffness and the equivalent damping coefficient are pre-set and are related to factors such as the material properties and temperature of the friction plate model and the wheel model.

[0118] S205, obtaining a fourth braking torque of the braking system in a last slipping state, and calculating a ratio of the fourth braking torque to an equivalent spring stiffness.

[0119] In the embodiment of the present application, the braking torque (ie, the fourth braking torque) T of the braking system in the most recent sliding state is retrieved. brk2 , and calculate the fourth braking torque T brk1 Ratio T to the equivalent spring stiffness K brk2 / K.

[0120] S206: Construct a third expression for characterizing the angle of the wheel model relative to the friction plate model by integrating the second expression and superimposing the second expression with the ratio.

[0121] In the embodiment of the present application, for the angle of the wheel model relative to the friction plate model, a corresponding expression (i.e., a third expression) is constructed. The third expression is shown in the following formula (6), where the integration start time is the time when the brake system starts to enter the locked state this time:

[0122] whl_ang=∫whl_spd+T brk2 / K (6)

[0123] Where whl_ang is the angle. In order to make the braking torque continuous when the braking system switches from the sliding state to the locking state, the initial value of the angle is T brk2 / K.

[0124] S207, constructing a fourth expression for characterizing the spring torque using the equivalent spring stiffness and the third expression.

[0125] In the embodiment of the present application, for the spring torque, a corresponding expression (i.e., a fourth expression) is constructed, and the fourth expression is shown in the following formula (7):

[0126] T brk1-1 =K*whl_ang (7)

[0127] Among them, T brk1-1 is the spring torque.

[0128] S208: construct a fifth expression for characterizing the damping torque using the equivalent damping coefficient and the second expression.

[0129] In the embodiment of the present application, for the damping torque, a corresponding expression (i.e., the fifth expression) is constructed, and the fifth expression is shown in the following formula (8):

[0130] T brk1-2 =C*whl_spd (8)

[0131] Among them, T brk1-2 is the damping torque, and C is the equivalent damping coefficient.

[0132] S209, setting the first friction torque equal to the sum of the spring torque and the damping torque, and solving the fourth expression and the fifth expression to obtain the first friction torque.

[0133] In the embodiment of the present application, let the first friction torque T brk1 = Spring torque T brk1-1 + Damping torque T brk1-2 , that is, Tbrk1 =K*whl_ang+C*whl_spd, where the first friction torque T brk1 As the unknown quantity, the first friction torque T can be obtained by solving brk1 .

[0134] Through the above description, the friction plate modeling method of a brake system provided by the embodiment of the present application proposes a connection relationship between the friction plate model and the wheel model when the spring damping system is equivalent to the locked state, and uses this physical relationship to solve the solution of the braking torque in the locked state. It can continuously switch from the sliding state to the locked state, and can accurately and stably simulate the vehicle running characteristics when the vehicle is braked, which provides great help for the simulation test of the brake control system algorithm. Compared with the traditional modeling method, it has the following advantages:

[0135] 1) It can accurately simulate the braking torque of the vehicle in a locked state. By adjusting the stiffness and damping, the braking torque in the locked state can be infinitely close to the actual vehicle data;

[0136] 2) When the braking system switches from the sliding state to the locking state, the torque changes continuously, and when the locking state switches from the sliding state to the sliding state, the static friction force switches to the dynamic friction force, which is also consistent with the real physical laws;

[0137] 3) This modeling method has few assumptions, and the torque calculation function is continuous when the sliding state switches to the locking state, which makes the model extremely stable.

[0138] A method for modeling a friction plate of a brake system provided in an embodiment of the present application is introduced above, and a device for executing the above-mentioned method for modeling a friction plate of a brake system will be introduced below.

[0139] See also Figure 7 , Figure 7 A schematic structural diagram of a friction plate modeling device for a brake system provided in an embodiment of the present application.

[0140] like Figure 7 As shown, a friction plate modeling device for a brake system provided in an embodiment of the present application includes:

[0141] A determination module 10, used to determine a first braking state of the braking system at a current moment;

[0142] The calculation module 20 is used to calculate the first friction torque between the friction plate model and the wheel model when the first braking state is a locked state based on the assumption that the connection relationship is a spring damping system. The first friction torque is the first braking torque of the braking system in the locked state.

[0143] In a possible implementation, the computing module 20 is further configured to:

[0144] When the first braking state is a slipping state, the first friction plate temperature of the friction plate model at the current moment and the first wheel cylinder pressure of the braking system at the current moment are obtained; the second friction torque between the friction plate model and the wheel model is calculated according to the first friction plate temperature and the first wheel cylinder pressure, and the second friction torque is the second braking torque of the braking system in the slipping state.

[0145] In a possible implementation, the determination module 10 is specifically configured to:

[0146] Retrieve the second braking state of the braking system at the previous moment; when the second braking state is empty or the second braking state is a slipping state, determine the equivalent wheel speed of the wheel model at the current moment; determine whether the equivalent wheel speed is zero; if so, determine that the first braking state is a locked state; if not, determine that the first braking state is a slipping state.

[0147] In a possible implementation, the determination module 10 for determining the equivalent wheel speed of the wheel model at the current moment is specifically used to:

[0148] Obtain the first wheel speed of the wheel model at the previous moment and the second wheel speed at the current moment; calculate the product of the first wheel speed and the second wheel speed; when the product is greater than zero, determine the equivalent wheel speed to be the second wheel speed; when the product is less than or equal to zero, determine the equivalent wheel speed to be zero.

[0149] In a possible implementation, the determination module 10 is further configured to:

[0150] When the second braking state is a locking state, the third braking torque of the braking system at the previous moment is obtained; the second friction plate temperature of the friction plate model at the current moment, and the second wheel cylinder pressure of the braking system at the current moment are obtained; the maximum static friction force between the friction plate model and the wheel model is calculated according to the second friction plate temperature and the second wheel cylinder pressure; when the third braking torque is greater than the maximum static friction force, the first braking state is determined to be a slipping state; when the third braking torque is less than or equal to the maximum static friction force, the first braking state is determined to be a locking state.

[0151] In a possible implementation, the calculation module 20 for calculating the first friction torque between the friction plate model and the wheel model based on the assumption that the connection relationship is a spring damping system is specifically configured to:

[0152] Obtain the driving torque, road load torque and wheel moment of inertia of the wheel model at the current moment; construct a first expression for characterizing the angular acceleration of the wheel model relative to the friction plate model according to the driving torque, road load torque, wheel moment of inertia and the first friction torque; construct a second expression for characterizing the angular velocity of the wheel model relative to the friction plate model by integrating the first expression; determine the equivalent spring stiffness and the equivalent damping coefficient; obtain the fourth braking torque of the braking system in the last slipping state, and calculate the ratio of the fourth braking torque to the equivalent spring stiffness; construct a third expression for characterizing the angle of the wheel model relative to the friction plate model by integrating the second expression and superimposing it with the ratio; construct a fourth expression for characterizing the spring torque using the equivalent spring stiffness and the third expression; construct a fifth expression for characterizing the damping torque using the equivalent damping coefficient and the second expression; let the first friction torque be equal to the sum of the spring torque and the damping torque, and solve the fourth expression and the fifth expression to obtain the first friction torque.

[0153] It should be noted that the detailed functions of each module in the embodiment of the present application can be found in the corresponding disclosed part of the embodiment of the friction plate modeling method of the above-mentioned braking system, and will not be repeated here.

[0154] The present application also provides an electronic device. Figure 8 , Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device in the embodiment of the present application may include but is not limited to fixed terminals such as mobile phones, notebook computers, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Figure 8 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0155] like Figure 8 As shown, the electronic device may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage device 808 to a random access memory (RAM) 803. When the electronic device is powered on, various programs and data required for the operation of the electronic device are also stored in the RAM 803. The processing device 801, the ROM 802, and the RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0156] Typically, the following devices may be connected to the I / O interface 805: input devices 806 including, for example, a touch screen, a touch pad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; output devices 807 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; storage devices 808 including, for example, a memory card, a hard disk, etc.; and communication devices 809. The communication device 809 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although Figure 8 An electronic device having various devices is shown, but it should be understood that it is not required to implement or possess all the devices shown. More or fewer devices may be implemented or possessed instead.

[0157] Also provided in an embodiment of the present application is a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any friction plate modeling method for a braking system provided in an embodiment of the present application.

[0158] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When one or more computer programs are executed by an electronic device, the electronic device can implement any friction plate modeling method of a braking system provided in an embodiment of the present application.

[0159] It should also be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the device embodiments provided by the present application, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines.

[0160] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0161] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0162] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a training device, or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, training device, or data center. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

Claims

1. A friction plate modeling method for a brake system, characterized in that: The friction plate modeling method of the brake system comprises: Determine a first braking state of the braking system at a current moment; When the first braking state is a locked state, a first friction torque between the friction plate model and the wheel model is calculated based on the assumption that the connection relationship is a spring damping system, and the first friction torque is the first braking torque of the braking system in the locked state.

2. The friction plate modeling method of the brake system according to claim 1, characterized in that: The friction plate modeling method of the brake system also includes: When the first braking state is a sliding state, obtaining a first friction plate temperature of the friction plate model at a current moment and a first wheel cylinder pressure of the braking system at a current moment; A second friction torque between the friction plate model and the wheel model is calculated according to the first friction plate temperature and the first wheel cylinder pressure, where the second friction torque is a second braking torque of the brake system in a slip state.

3. The friction plate modeling method of the brake system according to claim 1, characterized in that: The determining of the first braking state of the braking system at the current moment includes: Retrieving the second braking state of the braking system at the last moment; When the second braking state is empty or the second braking state is a slipping state, determining an equivalent wheel speed of the wheel model at a current moment; Determining whether the equivalent wheel speed is zero; If so, determining that the first braking state is a locking state; If not, it is determined that the first braking state is a sliding wear state.

4. The friction plate modeling method of the brake system according to claim 3, characterized in that: The determining the equivalent wheel speed of the wheel model at the current moment includes: Obtaining a first wheel speed of the wheel model at a previous moment and a second wheel speed at a current moment; calculating the product of the first wheel speed and the second wheel speed; When the product is greater than zero, determining the equivalent wheel speed to be the second wheel speed; When the product is less than or equal to zero, the equivalent wheel speed is determined to be zero.

5. The friction plate modeling method of the brake system according to claim 3, characterized in that: The determining of the first braking state of the braking system at the current moment also includes: When the second braking state is a locking state, obtaining a third braking torque of the braking system at a previous moment; Acquire a second friction plate temperature of the friction plate model at the current moment and a second wheel cylinder pressure of the brake system at the current moment; calculating the maximum static friction force between the friction plate model and the wheel model according to the second friction plate temperature and the second wheel cylinder pressure; When the third braking torque is greater than the maximum static friction force, determining that the first braking state is a sliding friction state; When the third braking torque is less than or equal to the maximum static friction force, it is determined that the first braking state is a locking state.

6. The friction plate modeling method of a brake system according to claim 1, characterized in that: The calculating the first friction torque between the friction plate model and the wheel model based on the assumption that the connection relationship is a spring damping system includes: Obtaining the driving torque, road load torque and wheel rotational inertia of the wheel model at the current moment; constructing a first expression for characterizing the angular acceleration of the wheel model relative to the friction plate model according to the driving torque, the road load torque, the wheel moment of inertia and the first friction torque; By performing an integration operation on the first expression, a second expression for characterizing the angular velocity of the wheel model relative to the friction plate model is constructed; Determine the equivalent spring stiffness and equivalent damping coefficient; Acquire a fourth braking torque of the braking system in a last slipping state, and calculate a ratio of the fourth braking torque to the equivalent spring stiffness; By integrating the second expression and superimposing it with the ratio, a third expression for characterizing the angle of the wheel model relative to the friction plate model is constructed; Using the equivalent spring stiffness and the third expression, construct a fourth expression for characterizing the spring torque; Using the equivalent damping coefficient and the second expression, construct a fifth expression for characterizing the damping torque; The first friction torque is set equal to the sum of the spring torque and the damping torque, and the fourth expression and the fifth expression are solved to obtain the first friction torque.

7. A friction plate modeling device for a brake system, characterized in that: The friction plate modeling device of the brake system comprises: A determination module, used to determine a first braking state of the braking system at a current moment; A calculation module is used to calculate a first friction torque between a friction plate model and a wheel model when the first braking state is a locked state based on the assumption that the connection relationship is a spring damping system, wherein the first friction torque is a first braking torque of the braking system in a locked state.

8. A computer program product, characterized in that It comprises computer-readable instructions, and when the computer-readable instructions are executed on an electronic device, the electronic device implements the friction plate modeling method of the brake system as claimed in any one of claims 1 to 6.

9. An electronic device, characterized in that: The method comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the electronic device can implement the friction plate modeling method of the brake system as described in any one of claims 1 to 6.

10. A computer storage medium, characterized in that: The storage medium carries one or more computer programs, which, when executed by an electronic device, enable the electronic device to implement the friction plate modeling method for a brake system as described in any one of claims 1 to 6.

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