A robust predictive control method and device for wheel cylinder pressure in an automobile braking system

Abstract

The present invention relates to a robust predictive control method for wheel cylinder pressure of an automobile brake system, comprising: a hydraulic control unit controlling a high-pressure supply unit to establish a stable high-pressure source; the hydraulic control unit calculating a target hydraulic pressure of a brake wheel cylinder; the hydraulic control unit obtaining the hydraulic pressure of the brake wheel cylinder in a current sampling period; the hydraulic control unit obtaining a pre-stored discretized wheel cylinder hydraulic pressure model; the hydraulic control unit solving the lumped disturbance based on historical data of the hydraulic pressure of the brake wheel cylinder and control commands of a liquid inlet valve and a liquid outlet valve; the hydraulic control unit establishing a prediction equation for the wheel cylinder hydraulic pressure and predicting all possible values ​​of the hydraulic pressure of the brake wheel cylinder in a sampling period; evaluating all possible values ​​based on a preset evaluation method according to the target hydraulic pressure, determining an optimal prediction value and corresponding control commands for the liquid inlet valve and the liquid outlet valve; and controlling the liquid inlet valve and the liquid outlet valve according to the control commands for the liquid inlet valve and the liquid outlet valve corresponding to the optimal prediction value.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile braking, and in particular to a method and device for robust predictive control of wheel cylinder pressure in an automobile braking system. Background Art

[0002] The hydraulic brake system is a key component for ensuring vehicle safety. The implementation of active safety features such as anti-lock braking, anti-skid control, and electronic stability control depends largely on the control performance of the brake system's wheel cylinder hydraulic pressure.

[0003] Compared to linear solenoid valves, high-speed on-off valves are widely used in automotive hydraulic brake systems due to their low cost, fast response, and strong robustness. Given the discrete operating characteristics of high-speed on-off valves, which operate in full-open and full-close states, pulse-width modulation (PWM) control is typically used to control the average brake fluid flow through the on-off valve, thereby controlling the wheel cylinder hydraulic pressure. However, existing PWM control methods have the following major drawbacks: First, wheel cylinder hydraulic pressure control is essentially based on the relationship between the calibrated average flow rate of the on-off valve and the PWM duty cycle, and cannot directly quantify the relationship between the solenoid valve switching state and the wheel cylinder hydraulic pressure. Second, PWM control requires a PWM generator, increasing the cost of the hydraulic brake system and the complexity of the control algorithm. Third, factors such as model uncertainty, environmental changes, and uncertain disturbances in the hydraulic brake system can affect the control performance of the wheel cylinder hydraulic pressure. Parameter calibration is often used in engineering to address this issue, but it is labor-intensive and inefficient. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to provide a robust predictive control method and device for the wheel cylinder pressure of an automobile brake system. From the perspective of discrete switching of the solenoid valve, a direct quantitative relationship between the switching state of the inlet valve and the outlet valve and the wheel cylinder hydraulic pressure is established, and the control commands of the inlet valve and the outlet valve can be directly optimized, avoiding the use of a PWM generator; at the same time, the wheel cylinder hydraulic pressure model is identified online based on historical operating data, which can reduce the calibration workload, shorten the development cycle, and improve robustness.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present application provides a method for robust predictive control of wheel cylinder pressure in an automobile brake system, which is applied to an automobile brake system comprising: a hydraulic control unit, a high-pressure supply unit, a brake wheel cylinder, a low-pressure oil return unit, a liquid inlet valve, and a liquid outlet valve. The method comprises:

[0007] S1, the hydraulic control unit controls the high-pressure supply unit to establish a stable high-pressure source;

[0008] S2, the hydraulic control unit obtains a braking demand of the vehicle and calculates a target hydraulic pressure of the wheel brake cylinder according to the braking demand;

[0009] S3, the hydraulic control unit obtains the hydraulic pressure of the brake wheel cylinder in the current sampling period;

[0010] S4, the hydraulic control unit obtains a pre-stored discretized wheel cylinder hydraulic pressure model; wherein the discretized wheel cylinder hydraulic pressure model is used to solve the hydraulic pressure in the next sampling period based on the hydraulic pressure, lumped disturbance, and brake fluid flow rate of the brake wheel cylinder in the current sampling period, wherein the brake fluid flow rate is solved based on the correlation between a finite flow rate set and an effective control set of the inlet valve and the outlet valve in the current sampling period; the effective control set is a combination of effective control commands for the inlet valve and the outlet valve;

[0011] S5, the hydraulic control unit solves the lumped disturbance based on the historical data of the hydraulic pressure of the brake wheel cylinder and the control commands of the liquid inlet valve and the liquid outlet valve;

[0012] S6, the hydraulic control unit establishes a prediction equation for the wheel cylinder hydraulic pressure, and predicts all possible values ​​of the hydraulic pressure of the brake wheel cylinder in the following sampling period;

[0013] S7, the hydraulic control unit evaluates all possible values ​​according to the target hydraulic pressure based on a preset evaluation method, and determines an optimal predicted value and corresponding control commands for the liquid inlet valve and the liquid outlet valve;

[0014] S8, the hydraulic control unit controls the liquid inlet valve and the liquid outlet valve to open or close according to the control commands of the liquid inlet valve and the liquid outlet valve corresponding to the optimal predicted value.

[0015] In one implementation of the present application, the switch states of the liquid inlet valve and the liquid outlet valve are defined as:

[0016]

[0017] Where S v Indicates the switch state of the solenoid valve, subscript v=I indicates the liquid inlet valve, and v=O indicates the liquid outlet valve;

[0018] The control combination of the inlet valve and the outlet valve is defined as follows:

[0019] S=(S I ,S O )

[0020] The effective control set of the inlet valve and the outlet valve is:

[0021] S={S0,S1,S2}

[0022] Where S represents the effective control set of the inlet valve and the outlet valve, where S0 = (0, 0), S1 = (1, 0), and S2 = (0, 1).

[0023] In one implementation of the present application, the limited flow set is defined as:

[0024] U={Q0,Q1,Q2}

[0025] Where U represents the finite flow set of the brake wheel cylinder, Q0, Q1 and Q2 are the flow rates of the brake wheel cylinder corresponding to S0, S1 and S2 respectively, and are calculated using the following formula:

[0026]

[0027] Where C d is the solenoid valve flow coefficient, A v is the cross-sectional area of ​​the solenoid valve port, ρ is the brake fluid density, P s is the hydraulic pressure of the high-pressure supply unit, P0 is the hydraulic pressure of the low-pressure return unit, P w is the hydraulic pressure of the brake wheel cylinder.

[0028] In one implementation of the present application, the wheel cylinder hydraulic pressure model is:

[0029] Q w ∈U

[0030] Where β is the bulk modulus of the brake fluid, V0 is the initial volume of the wheel cylinder, and d w is the lumped disturbance, Q w is the brake fluid flow entering or out of the wheel cylinder;

[0031] Let y = P w , F=d w ,α=β / V0,u=Q w , the discretized wheel cylinder hydraulic pressure model is obtained as:

[0032] y(k+1)=y(k)+T s [F(k)+αu(k)],u(k)∈U

[0033] Where T s is the sampling period, y(k), F(k) and u(k) represent the values ​​of y, F and u at the kth sampling period respectively.

[0034] In one implementation of the present application, the lumped disturbance is solved using an algebraic parameter identification method based on historical data of the hydraulic pressure of the wheel brake cylinder and control commands of the fluid inlet valve and the fluid outlet valve.

[0035] In one implementation of the present application, the formula for solving the lumped disturbance is:

[0036]

[0037] In the formula is the estimated value of F, T F is the width of the historical data time window, T F =n F T s , n F is the number of sampling periods, and τ is the integral variable.

[0038] In one implementation of the present application, the prediction equation for the wheel cylinder hydraulic pressure is specifically:

[0039] u i =Q i ,(i=0,1,2)

[0040] Where subscript i=0, 1, 2 corresponds to different control combinations respectively. represents the predicted value of the wheel cylinder hydraulic pressure in the k+1th sampling period corresponding to the i-th control combination.

[0041] In one implementation of the present application, all possible values ​​are evaluated based on a PID-type cost function.

[0042] In one implementation of the present application, the PID cost function is specifically:

[0043] J i =[w1P i (k)+w2I i (k)+w3D i (k)] 2 +h i ,(i=0,1,2)

[0044] Where Ji is the cost function corresponding to the i-th control combination, w1, w2 and w3 are weight coefficients, P i (k), I i (k) and D i (k) are proportional term, integral term and differential term respectively, hi is the additional term;

[0045] The proportional term, integral term, and differential term are defined as:

[0046]

[0047] I(0)=0.

[0048]

[0049] The additional terms are defined as:

[0050]

[0051] Where ∞ represents positive infinity.

[0052] In a second aspect, the present application provides a robust predictive control device for wheel cylinder pressure in an automobile brake system, comprising: a target hydraulic pressure calculation module, a data processing and storage module, a wheel cylinder hydraulic pressure model module, an online parameter identification module, a wheel cylinder hydraulic pressure prediction module, and a cost function evaluation module;

[0053] The target hydraulic pressure calculation module is used to convert the braking demand obtained in the chassis domain and the autonomous driving domain into the target hydraulic pressure of the corresponding wheel cylinder based on the analysis of the current vehicle state;

[0054] The data processing and storage module is used to obtain the hydraulic pressure of the high-pressure supply unit, the hydraulic pressure of the low-pressure return unit, and the hydraulic pressure of the brake wheel cylinder; and store historical data of the wheel cylinder hydraulic pressure and historical control commands of the liquid inlet valve and the liquid outlet valve;

[0055] The wheel cylinder hydraulic pressure model module is used to construct an effective control combination of the inlet valve and the outlet valve, establish a finite flow set wheel cylinder hydraulic pressure model, and quantitatively characterize the relationship between the solenoid valve switch state and the wheel cylinder hydraulic pressure;

[0056] The online parameter identification module uses an algebraic parameter identification method to estimate the lumped disturbance of the wheel cylinder hydraulic pressure model in real time, and is used to correct the hydraulic pressure prediction equation of the wheel cylinder hydraulic pressure prediction model module;

[0057] The wheel cylinder hydraulic pressure prediction module applies a finite flow set of the wheel cylinder to a prediction equation to obtain a predicted value of the wheel cylinder hydraulic pressure at the next moment;

[0058] The cost function evaluation module is used to evaluate the predicted value of the wheel cylinder hydraulic pressure obtained by the hydraulic pressure prediction model module based on the target value of the brake wheel cylinder hydraulic pressure using a PID type cost function; obtain the optimal predicted value of the wheel cylinder hydraulic pressure and the corresponding optimal control combination of the inlet valve and the outlet valve by solving the optimization problem; and output it directly to the drive device of the inlet valve and the outlet valve to control the opening and closing of the inlet valve and the outlet valve, thereby realizing the control of the wheel cylinder hydraulic pressure.

[0059] The present invention has the following advantages due to the adoption of the above technical solution:

[0060] (1) Based on the discrete operating characteristics of the high-speed switching valve when fully open and fully closed, the present invention defines the effective control combination of the inlet valve and the outlet valve and the corresponding finite flow set of the wheel cylinder, establishes a finite flow set wheel cylinder hydraulic pressure model, and quantitatively characterizes the relationship between the switching state of the solenoid valve and the wheel cylinder hydraulic pressure.

[0061] (2) The present invention uses a PID-type cost function to optimize and evaluate the deviation between the predicted value and the target value of the wheel cylinder hydraulic pressure, selects the optimal predicted value of the wheel cylinder hydraulic pressure and the corresponding optimal control combination of the inlet valve and the outlet valve, and directly outputs them to the drive device of the inlet valve and the outlet valve, eliminating the PWM generator in the PWM wheel cylinder hydraulic pressure control method, reducing system cost and algorithm complexity.

[0062] (3) The present invention estimates the lumped disturbance in the wheel cylinder hydraulic pressure model online through an algebraic parameter identification method, and compensates the prediction model based on this, which not only improves the robustness of the wheel cylinder hydraulic pressure control algorithm but also reduces the calibration workload of the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Schematic diagram of a single-wheel hydraulic brake system for an automobile involved in the present invention;

[0064] Figure 2 This is a flow chart of a robust predictive control method for wheel cylinder hydraulic pressure of an automobile brake system in the present invention;

[0065] Figure 3 The diagram is a schematic diagram of a robust predictive control device for wheel cylinder hydraulic pressure in an automobile brake system according to the present invention. DETAILED DESCRIPTION

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0067] In one embodiment of the present application, Figure 1 , provides a vehicle (single wheel) hydraulic brake system. Figure 1As shown, it includes a high-pressure supply unit 1, a first pressure sensor 2, a liquid inlet valve 3, a brake wheel cylinder 4, a second pressure sensor 5, a liquid outlet valve 6, a low-pressure oil return unit 7 and a hydraulic pressure control unit 8. The high-pressure supply unit 1 is used to provide a stable and reliable high-pressure source; the first pressure sensor 2 is used to measure the hydraulic pressure of the high-pressure supply unit 1; the inlet valve 3 is a high-speed on-off valve, which is controlled to open and close to control the flow of brake fluid from the high-pressure supply unit 1 to the wheel cylinder 4, thereby achieving pressure increase control of the wheel cylinder 4; the outlet valve 6 is a high-speed on-off valve, which is controlled to open and close to control the flow of brake fluid from the wheel cylinder 4 to the low-pressure return unit 7, thereby achieving pressure reduction control of the wheel cylinder 4; the inlet valve 3 and the outlet valve 6 cooperate to achieve pressure increase and pressure reduction control of the wheel cylinder 4; the second pressure sensor 5 is used to measure the hydraulic pressure of the wheel cylinder 4; the low-pressure return unit 7 is used to recover brake fluid discharged from the wheel cylinder 4; the hydraulic pressure control unit 8 is used to obtain braking demand, calculate the target value of the wheel cylinder hydraulic pressure, collect signals from the first pressure sensor 2 and the second pressure sensor 5, run the proposed hydraulic pressure control algorithm, and control the switching states of the inlet valve 3 and the outlet valve 6.

[0068] like Figure 2 The robust predictive control method for wheel cylinder pressure of an automobile brake system in the embodiment of the present application is applied to a hydraulic control unit and mainly includes the following steps:

[0069] S1, the hydraulic control unit controls the high-pressure supply unit to establish a stable high-pressure source;

[0070] Specifically, the pressure supply unit includes but is not limited to a high-pressure accumulator type high-pressure supply unit and an electric power-assisted master cylinder type high-pressure supply unit.

[0071] S2, the hydraulic control unit obtains a braking demand of the vehicle and calculates a target hydraulic pressure of the wheel brake cylinder according to the braking demand;

[0072] Specifically, the hydraulic control unit obtains the braking requirements of the chassis domain and the autonomous driving domain, and combines the analysis of the current vehicle status to convert this braking demand into the target hydraulic pressure of the brake wheel cylinder.

[0073] S3, the hydraulic control unit obtains the hydraulic pressure of the brake wheel cylinder in the current sampling period;

[0074] Specifically, the hydraulic pressure acquisition method includes but is not limited to measurement through a pressure sensor and estimation through a hydraulic pressure estimation algorithm.

[0075] S4, the hydraulic control unit obtains a pre-stored discretized wheel cylinder hydraulic pressure model; wherein the discretized wheel cylinder hydraulic pressure model is used to solve the hydraulic pressure in the next sampling period based on the hydraulic pressure, lumped disturbance, and brake fluid flow rate of the brake wheel cylinder in the current sampling period, wherein the brake fluid flow rate is solved based on the correlation between a finite flow rate set and an effective control set of the inlet valve and the outlet valve in the current sampling period; the effective control set is a combination of effective control commands for the inlet valve and the outlet valve;

[0076] Specifically, in the embodiment of the present application, the switch states of the liquid inlet valve and the liquid outlet valve are defined as:

[0077]

[0078] Where S v Indicates the switch state of the solenoid valve, subscript v=I indicates the liquid inlet valve, and v=O indicates the liquid outlet valve;

[0079] The control combination of the inlet valve and the outlet valve is defined as follows:

[0080] S=(S I ,S O )

[0081] Consider the following three control combinations: (1) the inlet valve and the outlet valve are closed at the same time; (2) the inlet valve is open and the outlet valve is closed; (3) the inlet valve is closed and the outlet valve is open. Accordingly, the effective control set of the inlet valve and the outlet valve is:

[0082] S={S0,S1,S2}

[0083] Where S represents the effective control set of the inlet valve and the outlet valve, where S0 = (0, 0), S1 = (1, 0), and S2 = (0, 1).

[0084] Furthermore, the finite flow set is defined as:

[0085] U={Q0,Q1,Q2}

[0086] Where U represents the finite flow set of the brake wheel cylinder, Q0, Q1 and Q2 are the flow rates of the brake wheel cylinder corresponding to S0, S1 and S2 respectively, and are calculated using the following formula:

[0087]

[0088] Where C d is the solenoid valve flow coefficient, A v is the cross-sectional area of ​​the solenoid valve port, ρ is the brake fluid density, P s is the hydraulic pressure of the high-pressure supply unit, P0 is the hydraulic pressure of the low-pressure return unit, P w is the hydraulic pressure of the brake wheel cylinder.

[0089] In the embodiment of the present application, the wheel cylinder hydraulic pressure model of the finite flow set is defined as follows:

[0090] Q w ∈U

[0091] Where β is the bulk modulus of the brake fluid, V0 is the initial volume of the wheel cylinder, and d w is the lumped disturbance, Q w is the brake fluid flow entering or out of the wheel cylinder;

[0092] Let y = P w , F=d w ,α=β / V0,u=Q w , rewrite the wheel cylinder hydraulic pressure model of the finite flow set into the following form:

[0093] u∈U

[0094] The discretized wheel cylinder hydraulic pressure model is obtained as:

[0095] y(k+1)=y(k)+T s [F(k)+αu(k)],u(k)∈U

[0096] Where T s is the sampling period, y(k), F(k) and u(k) represent the values ​​of y, F and u at the kth sampling period respectively.

[0097] S5, the hydraulic control unit solves the lumped disturbance based on the historical data of the hydraulic pressure of the brake wheel cylinder and the control commands of the liquid inlet valve and the liquid outlet valve;

[0098] Specifically, based on the historical data of the hydraulic pressure of the wheel cylinder and the historical control command data of the inlet valve and the outlet valve, an algebraic parameter identification method is used to online identify the wheel cylinder hydraulic pressure model. The specific formula is as follows:

[0099]

[0100] In the formula is the estimated value of F, T F is the width of the historical data time window, T F =n F T s , n F is the number of sampling periods, and τ is the integral variable.

[0101] The methods for calculating the above integral include but are not limited to the complex trapezoidal formula and the complex Simpson formula. The present invention provides an example of using the complex trapezoidal formula to calculate the above integral, namely

[0102]

[0103] Where f(k)=(n F -2k)y(k)+αkT s (n F -k)u(k).

[0104] S6, the hydraulic control unit establishes a prediction equation for the wheel cylinder hydraulic pressure, and predicts all possible values ​​of the hydraulic pressure of the brake wheel cylinder in the following sampling period;

[0105] The prediction equation for the wheel cylinder hydraulic pressure is as follows:

[0106] u i =Q i ,(i=0,1,2)

[0107] Where subscript i=0, 1, 2 corresponds to different control combinations respectively. represents the predicted value of the wheel cylinder hydraulic pressure in the k+1th sampling period corresponding to the i-th control combination.

[0108] S7, the hydraulic control unit evaluates all possible values ​​according to the target hydraulic pressure based on a preset evaluation method, and determines an optimal predicted value and corresponding control commands for the liquid inlet valve and the liquid outlet valve;

[0109] Specifically, the specific formula of the proportional-integral-derivative (PID) cost function is as follows:

[0110] J i =[w1P i (k)+w2I i (k)+w3D i (k)] 2 +h i ,(i=0,1,2)

[0111] Where Ji is the cost function corresponding to the i-th control combination, w1, w2 and w3 are weight coefficients, P i (k), I i (k) and D i (k) are the proportional term, integral term and differential term respectively, and hi is an additional term used to limit the range of the predicted value of the wheel cylinder hydraulic pressure.

[0112] The proportional term, integral term, and differential term are defined as:

[0113]

[0114] I(0)=0.

[0115]

[0116] Where y d (k+1) is the target value of the wheel cylinder hydraulic pressure in the k+1th sampling period, and its value can be taken as y d (k) Or it can be obtained by extrapolation based on historical data of the wheel cylinder hydraulic pressure target value.

[0117] The additional term in the cost function is defined as

[0118]

[0119] Where ∞ represents positive infinity.

[0120] Furthermore, the optimal predicted value of the wheel cylinder hydraulic pressure and the corresponding optimal control combination of the inlet valve and outlet valve are solved. The optimization problem is specifically:

[0121]

[0122]

[0123] u i =Q i ,(i=0,1,2)

[0124] Methods for solving the above optimization problem include but are not limited to enumeration methods, etc.

[0125] S8, the hydraulic control unit controls the liquid inlet valve and the liquid outlet valve to open or close according to the control commands of the liquid inlet valve and the liquid outlet valve corresponding to the optimal predicted value.

[0126] like Figure 3 In another aspect of the embodiment of the present application, a corresponding device is also provided, which can be implemented in the hydraulic control unit in the form of hardware or software.

[0127] A robust predictive control device for wheel cylinder hydraulic pressure in an automobile brake system, comprising a target hydraulic pressure calculation module, a data processing and storage module, a wheel cylinder hydraulic pressure model module, an online parameter identification module, a wheel cylinder hydraulic pressure prediction module, and a cost function evaluation module;

[0128] The target hydraulic pressure calculation module is used to convert the braking demand obtained in the chassis domain and the autonomous driving domain into the target hydraulic pressure of the corresponding wheel cylinder based on the analysis of the current vehicle state;

[0129] The data processing and storage module is used to obtain the hydraulic pressure of the high-pressure supply unit, the hydraulic pressure of the low-pressure return unit, and the hydraulic pressure of the brake wheel cylinder; and store historical data of the wheel cylinder hydraulic pressure and historical control commands of the liquid inlet valve and the liquid outlet valve;

[0130] The wheel cylinder hydraulic pressure model module is used to construct an effective control combination of the inlet valve and the outlet valve, establish a finite flow set wheel cylinder hydraulic pressure model, and quantitatively characterize the relationship between the solenoid valve switch state and the wheel cylinder hydraulic pressure;

[0131] The online parameter identification module uses an algebraic parameter identification method to estimate the lumped disturbance of the wheel cylinder hydraulic pressure model in real time, and is used to correct the hydraulic pressure prediction equation of the wheel cylinder hydraulic pressure prediction model module;

[0132] The wheel cylinder hydraulic pressure prediction module applies a finite flow set of the wheel cylinder to a prediction equation to obtain a predicted value of the wheel cylinder hydraulic pressure at the next moment;

[0133] The cost function evaluation module is used to evaluate the predicted value of the wheel cylinder hydraulic pressure obtained by the hydraulic pressure prediction model module based on the target value of the brake wheel cylinder hydraulic pressure using a PID type cost function; obtain the optimal predicted value of the wheel cylinder hydraulic pressure and the corresponding optimal control combination of the inlet valve and the outlet valve by solving the optimization problem; and output it directly to the drive device of the inlet valve and the outlet valve to control the opening and closing of the inlet valve and the outlet valve, thereby realizing the control of the wheel cylinder hydraulic pressure.

[0134] In summary, the method and device in the embodiment of the present application establish a direct quantitative relationship between the switching state of the inlet valve and the outlet valve and the wheel cylinder hydraulic pressure from the perspective of the discrete switch of the solenoid valve, and can then directly optimize the control commands of the inlet valve and the outlet valve, avoiding the use of a PWM generator; at the same time, the wheel cylinder hydraulic pressure model is identified online based on historical operating data, which can reduce the calibration workload, shorten the development cycle, and improve robustness.

[0135] The present application also provides a computer-readable storage medium, which includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the above method. The specific implementation process will not be repeated here.

[0136] The present application also provides a computer device. This embodiment of the computer device includes a processor, a memory, and a computer program stored in the memory and executable by the processor. When the processor executes the computer program, the aforementioned method of the embodiment is implemented. To avoid repetition, a detailed description thereof is omitted here. Alternatively, when the processor executes the computer program, the functions of each model / unit in the apparatus of the embodiment are implemented. To avoid repetition, a detailed description thereof is omitted here.

[0137] A computer device may be a desktop computer, laptop, PDA, server, or cloud server, among other computing devices. A computer device may include, but is not limited to, a processor and memory. Those skilled in the art will appreciate that a computer device may include more or fewer components than shown, or a combination of certain components, or different components. For example, a computer device may also include input / output devices, network access devices, and buses.

[0138] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0139] Memory can be an internal storage unit of a computer device, such as a computer device's hard drive or memory. It can also be an external storage device, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, or a flash memory card. Furthermore, memory can include both internal storage units and external storage devices. Memory is used to store computer programs and other programs and data required by the computer device. Memory can also be used to temporarily store data that has been output or is about to be output.

[0140] Those skilled in the art will 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.

[0141] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the above units is merely a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0142] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) or a processor to perform some of the steps of the above-mentioned methods of various embodiments of the present invention. The aforementioned storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., various media that can store program code.

[0143] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A robust predictive control method for wheel cylinder pressure in an automobile braking system, applied to an automobile braking system, the automobile braking system comprising: A hydraulic control unit, a high-pressure supply unit, a brake wheel cylinder, a low-pressure oil return unit, a liquid inlet valve and a liquid outlet valve, wherein the method comprises: S1, the hydraulic control unit controls the high-pressure supply unit to establish a stable high-pressure source; S2, the hydraulic control unit obtains a braking demand of the vehicle and calculates a target hydraulic pressure of the wheel brake cylinder according to the braking demand; S3, the hydraulic control unit obtains the hydraulic pressure of the brake wheel cylinder in the current sampling period; S4, the hydraulic control unit obtains a pre-stored discretized wheel cylinder hydraulic pressure model; wherein the discretized wheel cylinder hydraulic pressure model is used to solve the hydraulic pressure in the next sampling period based on the hydraulic pressure, lumped disturbance, and brake fluid flow rate of the brake wheel cylinder in the current sampling period, wherein the brake fluid flow rate is solved based on the correlation between a finite flow rate set and an effective control set of the inlet valve and the outlet valve in the current sampling period; the effective control set is a combination of effective control commands for the inlet valve and the outlet valve; S5, the hydraulic control unit solves the lumped disturbance based on the historical data of the hydraulic pressure of the brake wheel cylinder and the control commands of the liquid inlet valve and the liquid outlet valve; S6, the hydraulic control unit establishes a prediction equation for the wheel cylinder hydraulic pressure, and predicts all possible values ​​of the hydraulic pressure of the brake wheel cylinder in the following sampling period; S7, the hydraulic control unit evaluates all possible values ​​according to the target hydraulic pressure based on a preset evaluation method, and determines an optimal predicted value and corresponding control commands for the liquid inlet valve and the liquid outlet valve; S8, the hydraulic control unit controls the liquid inlet valve and the liquid outlet valve to open or close according to the control commands of the liquid inlet valve and the liquid outlet valve corresponding to the optimal predicted value.

2. The method for robust predictive control of wheel cylinder pressure in a vehicle brake system according to claim 1, characterized in that: The switch states of the liquid inlet valve and the liquid outlet valve are defined as: Where S v Indicates the switch state of the solenoid valve, subscript v=I indicates the liquid inlet valve, and v=O indicates the liquid outlet valve; The control combination of the inlet valve and the outlet valve is defined as follows: S=(S I ,S O ) The effective control set of the inlet valve and the outlet valve is: S={S0,S1,S2} Where S represents the effective control set of the inlet valve and the outlet valve, where S0 = (0, 0), S1 = (1, 0), and S2 = (0, 1).

3. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 2, characterized in that: The finite flow set is defined as: U={Q0,Q1,Q2} Where U represents the finite flow set of the brake wheel cylinder, Q0, Q1 and Q2 are the flow rates of the brake wheel cylinder corresponding to S0, S1 and S2 respectively, and are calculated using the following formula: Where C d is the solenoid valve flow coefficient, A v is the cross-sectional area of ​​the solenoid valve port, ρ is the brake fluid density, P s is the hydraulic pressure of the high-pressure supply unit, P0 is the hydraulic pressure of the low-pressure return unit, P w is the hydraulic pressure of the brake wheel cylinder.

4. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 3, characterized in that: The wheel cylinder hydraulic pressure model is: Where β is the bulk modulus of the brake fluid, V0 is the initial volume of the wheel cylinder, and d w is the lumped disturbance, Q w is the brake fluid flow entering or out of the wheel cylinder; Let y = P w , F=d w ,α=β / V0,u=Q w , the discretized wheel cylinder hydraulic pressure model is obtained as: y(k+1)=y(k)+T s [F(k)+αu(k)],u(k)∈U Where T s is the sampling period, y(k), F(k) and u(k) represent the values ​​of y, F and u at the kth sampling period respectively.

5. The method for robust predictive control of wheel cylinder pressure in a vehicle brake system according to claim 4, characterized in that: The lumped disturbance is solved by using an algebraic parameter identification method based on historical data of the hydraulic pressure of the brake wheel cylinder and control commands of the fluid inlet valve and the fluid outlet valve.

6. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 5, characterized in that: The formula for solving the lumped disturbance is: In the formula is the estimated value of F, T F is the width of the historical data time window, T F =n F T s , n F is the number of sampling periods, and τ is the integral variable.

7. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 6, characterized in that: The prediction equation of the wheel cylinder hydraulic pressure is specifically: Where subscript i=0, 1, 2 corresponds to different control combinations respectively. represents the predicted value of the wheel cylinder hydraulic pressure in the k+1th sampling period corresponding to the i-th control combination.

8. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 7, characterized in that: All possible values ​​are evaluated based on a PID-type cost function.

9. The method for robust predictive control of wheel cylinder pressure in an automobile brake system according to claim 8, characterized in that: The PID type cost function is specifically: Where Ji is the cost function corresponding to the i-th control combination, w1, w2 and w3 are weight coefficients, P i (k), I i (k) and D i (k) are proportional term, integral term and differential term respectively, hi is the additional term; The proportional term, integral term, and differential term are defined as: The additional terms are defined as: Where ∞ represents positive infinity.

10. A robust predictive control device for wheel cylinder pressure in an automobile braking system, characterized in that: include: Target hydraulic pressure calculation module, data processing and storage module, wheel cylinder hydraulic pressure model module, online parameter identification module, wheel cylinder hydraulic pressure prediction module, cost function evaluation module; The target hydraulic pressure calculation module is used to convert the braking demand obtained in the chassis domain and the autonomous driving domain into the target hydraulic pressure of the corresponding wheel cylinder based on the analysis of the current vehicle state; The data processing and storage module is used to obtain the hydraulic pressure of the high-pressure supply unit, the hydraulic pressure of the low-pressure return unit, and the hydraulic pressure of the brake wheel cylinder; and store historical data of the wheel cylinder hydraulic pressure and historical control commands of the liquid inlet valve and the liquid outlet valve; The wheel cylinder hydraulic pressure model module is used to construct an effective control combination of the inlet valve and the outlet valve, establish a finite flow set wheel cylinder hydraulic pressure model, and quantitatively characterize the relationship between the solenoid valve switch state and the wheel cylinder hydraulic pressure; The online parameter identification module uses an algebraic parameter identification method to estimate the lumped disturbance of the wheel cylinder hydraulic pressure model in real time, and is used to correct the hydraulic pressure prediction equation of the wheel cylinder hydraulic pressure prediction model module; The wheel cylinder hydraulic pressure prediction module applies a finite flow set of the wheel cylinder to a prediction equation to obtain a predicted value of the wheel cylinder hydraulic pressure at the next moment; The cost function evaluation module is used to evaluate the predicted value of the wheel cylinder hydraulic pressure obtained by the hydraulic pressure prediction model module based on the target value of the brake wheel cylinder hydraulic pressure using a PID type cost function; obtain the optimal predicted value of the wheel cylinder hydraulic pressure and the corresponding optimal control combination of the inlet valve and the outlet valve by solving the optimization problem; and output it directly to the drive device of the inlet valve and the outlet valve to control the opening and closing of the inlet valve and the outlet valve, thereby realizing the control of the wheel cylinder hydraulic pressure.

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