Control method of electronic hydraulic brake system

Abstract

The invention relates to the technical field of electronic hydraulic brake system control, in particular to an electronic hydraulic brake system control method. The method comprises the following steps that firstly, according to the operation principle of the electronic hydraulic braking system, a simplified model of the electronic hydraulic braking system under external interference is established, and an expected state is set; secondly, obtaining an error function according to the simplified model and the expected state; obtaining a sliding mode surface function according to the error function; then, according to the error function and the sliding mode surface function, a cascade sliding mode law of the electronic hydraulic braking system is obtained; and finally, estimating the external interference by using a composite interference observer to obtain an estimated value of the external interference, and compensating the estimated value to the cascade sliding mode law to obtain an anti-interference cascade sliding mode law. By means of the method, the anti-interference capacity and control precision of the electronic hydraulic braking system can be effectively improved, and therefore the stability and safety of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic hydraulic brake system control, and in particular to an electronic hydraulic brake system control method. Background Art

[0002] With the rapid development of the automobile industry, the safety performance requirements of vehicles are getting higher and higher. As an important part of vehicle safety, the performance of the braking system is directly related to the driving safety of the vehicle and the safety of life and property of passengers. In recent years, the electronic hydraulic braking system has gradually become a hot spot in the research of automobile braking systems. The electronic hydraulic braking system accurately controls the hydraulic braking pressure through the electronic control unit, which can not only achieve faster and more accurate braking response, but also effectively improve the overall braking performance of the vehicle.

[0003] In practical applications, electronic hydraulic brake systems often face various external interferences and uncertainties, such as changes in road conditions, changes in brake friction coefficients, and hysteresis and nonlinear characteristics of the hydraulic system. These factors will affect the response speed and control accuracy of the brake system, and may even cause system failure. Therefore, studying an electronic hydraulic brake system control method with strong anti-interference ability and high control accuracy is of great significance for improving vehicle braking safety and reliability.

[0004] The present invention proposes a control method for an electronic hydraulic brake system, aiming to improve the adaptability and control accuracy of the electronic hydraulic brake system under complex working conditions. By introducing the anti-interference sliding mode control technology, the uncertainty and nonlinear problems of the system can be effectively overcome, and the robustness of the system can be improved. In addition, the cascade control structure can realize the coordinated control of multiple control variables in the system, further enhancing the stability and response speed of the system. The control method can not only maintain the high performance of the system under various complex working conditions, but also significantly improve the braking safety and ride comfort of the vehicle. Summary of the invention

[0005] The present invention provides an electronic hydraulic brake system control method for solving the above technical problems. First, according to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and an expected state is set; the simplified model includes a simplified speed loop model and a simplified pressure loop model; secondly, according to the simplified speed loop model, the simplified pressure loop model and the expected state, an error function is obtained; according to the error function, a sliding surface function is obtained; then, according to the error function and the sliding surface function, a cascade sliding mode law of the electronic hydraulic brake system is obtained; finally, a composite disturbance observer is used to estimate the external interference, an estimated value of the external interference is obtained, and the estimated value is compensated to the cascade sliding mode law to obtain an anti-interference cascade sliding mode law.

[0006] A method for controlling an electronic hydraulic brake system comprises the following steps:

[0007] S1. According to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and an expected state is set; the simplified model includes a simplified speed loop model and a simplified pressure loop model;

[0008] S2, obtaining an error function according to the simplified model of the velocity loop, the simplified model of the pressure loop and the desired state; obtaining a sliding surface function according to the error function;

[0009] S3, obtaining a speed loop cascade sliding mode control law and a pressure loop cascade sliding mode control law of the electronic hydraulic brake system according to the error function and the sliding surface function;

[0010] S4. Use the first composite disturbance observer and the second composite disturbance observer to estimate the external disturbance to obtain an external disturbance estimation value, and compensate the external disturbance estimation value to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law.

[0011] Furthermore, according to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and the simplified model includes the simplified model of the speed loop and the simplified model of the pressure loop; the speed loop is the part from the motor torque to the push rod displacement, and the simplified model of the speed loop is:

[0012]

[0013] Among them, m is the equivalent mass of the master cylinder push rod, c is the equivalent damping of the master cylinder push rod, k is the equivalent stiffness of the master cylinder push rod, and x is the displacement of the master cylinder push rod. is the first derivative of x, is the second-order derivative of x, T is the motor output torque, k1 is the ratio of the speed mechanism transmission ratio to the pinion radius, d x for the external interference;

[0014] The pressure ring is the part where the push rod moves to the push rod liquid pressure. The simplified model of the pressure ring is:

[0015]

[0016] in, is the first-order derivative of the actual hydraulic pressure P of the master cylinder, A is the piston area of ​​the brake chamber, V is the volume of the liquid in the brake chamber, K e is the bulk modulus, d P is the external interference.

[0017] Furthermore, we set the expected state Pd , where P d is the expected value of the actual hydraulic pressure of the master cylinder; according to the expected state, the error function is obtained as follows:

[0018] e1=PP d ;

[0019]

[0020] Among them, e1 is the actual hydraulic pressure error of the main cylinder, and e2 is the displacement speed error of the main cylinder push rod. The expected value of the master cylinder push rod displacement speed.

[0021] Furthermore, according to the error function, the sliding surface function is obtained as follows:

[0022] s1=e1+λ 11 ∫e1dt;

[0023] s2=e2+λ 21 ∫e2dt;

[0024] Among them, s1 is the actual hydraulic pressure sliding surface of the main cylinder, s2 is the displacement speed sliding surface of the main cylinder push rod, and λ 11 and λ 21 are the controller parameters to be designed, and are all positive numbers, and t is the time.

[0025] Further, according to the error function and the sliding surface function, the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law of the electronic hydraulic brake system are obtained; the speed loop cascade sliding mode control law is:

[0026]

[0027] The pressure loop cascade sliding mode control law is:

[0028]

[0029] Among them, λ 12 and λ 22 are the controller parameters to be designed, and they are all positive numbers.

[0030] Furthermore, the external disturbance is estimated by using the speed loop composite disturbance observer and the pressure loop composite disturbance observer to obtain the external disturbance estimation value; the speed loop composite disturbance observer is:

[0031]

[0032] The pressure loop composite disturbance observer is:

[0033]

[0034] Among them, ζ1, ζ2, η1, η2, z1, z2, z3 and z4 are intermediate variables. are the first-order derivatives of z1, z2, z3, and z4 respectively, are the error function estimates of e1 and e2 respectively, They are The first-order derivative of , κ1, κ2, κ3, κ4, γ1, γ2, γ3 and γ4 are the parameters of the composite disturbance observer to be designed, and is the estimated value of the external interference.

[0035] Further, the external disturbance estimation value is compensated to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law; the speed loop anti-interference cascade sliding mode control law is:

[0036]

[0037] The anti-interference cascade sliding mode control law of the pressure loop is:

[0038]

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. By introducing a cascade control structure, the present invention realizes coordinated control of multiple control variables in an electronic hydraulic brake system. Cascade control not only improves the stability of the system, but also effectively manages and adjusts the mutual influence between different variables under complex working conditions, ensuring the overall coordination and efficiency of the brake system.

[0041] 2. Sliding mode control technology significantly improves the control accuracy and response speed of the electronic hydraulic brake system. Sliding mode control can effectively deal with the nonlinearity and uncertainty of the system, making the adjustment of brake pressure faster and more accurate, thereby improving the braking performance of the vehicle and enhancing driving safety.

[0042] 3. The composite disturbance observer can observe and estimate the external disturbance in the system in real time. By timely acquiring and analyzing the disturbance information, the system can quickly adjust the control strategy, significantly improving the anti-interference ability of the electronic hydraulic brake system under complex working conditions and ensuring the stability of the braking performance.

[0043] 4. An error prediction mechanism is added to the composite disturbance observer, which can predict and compensate for the impact of disturbances on the system in advance. This mechanism enables the system to respond before the disturbance occurs, significantly improving control accuracy and response speed. Error prediction enables the control system to quickly and accurately adjust the brake pressure, improving the safety and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the process of the present invention;

[0045] Figure 2 It is a simplified model of the electronic hydraulic system;

[0046] Figure 3 It is a block diagram of the cascade control structure. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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 embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the modern automobile industry, electronic hydraulic brake systems are gaining more and more attention. Electronic hydraulic brake systems precisely control hydraulic brake pressure through electronic control units, which can not only provide faster braking response and higher braking accuracy, but also significantly improve the overall braking performance and safety of vehicles. However, in complex driving environments and variable working conditions, the control accuracy and reliability of electronic hydraulic brake systems face severe challenges. Electronic hydraulic brake systems need to maintain stable and efficient braking performance under various driving conditions. For example, in cases of slippery roads, emergency braking, and continuous braking, the brake system must respond quickly and maintain precise control to ensure vehicle safety. Traditional control methods often find it difficult to ensure sufficient control accuracy and response speed when faced with system nonlinearity and external interference, thereby affecting the braking effect and safety of the vehicle. To this end, the present invention provides a control method for an electronic hydraulic brake system, which aims to improve the adaptability and control accuracy of the electronic hydraulic brake system under complex working conditions. By introducing anti-interference sliding mode control technology, the uncertainty and nonlinear problems of the system can be effectively overcome, and the robustness of the system can be improved. In addition, the cascade control structure can realize coordinated control of multiple control variables in the system, further enhancing the stability and response speed of the system. The control method can not only maintain the high performance of the system under various complex working conditions, but also significantly improve the braking safety and riding comfort of the vehicle. In order to illustrate the feasibility of the present invention, two specific embodiments will be described below.

[0049] Embodiment 1

[0050] In the embodiment of the present application, an electronic hydraulic brake system control method is adopted; the specific implementation process is as follows Figure 1 As shown, first, according to the operating principle of the electronic hydraulic braking system, a simplified model of the electronic hydraulic braking system under external interference is established, and an expected state is set; the simplified model includes a simplified speed loop model and a simplified pressure loop model; secondly, according to the simplified speed loop model, the simplified pressure loop model and the expected state, an error function is obtained; according to the error function, a sliding surface function is obtained; then, according to the error function and the sliding surface function, the cascade sliding mode law of the electronic hydraulic braking system is obtained; finally, a composite interference observer is used to estimate the external interference to obtain an estimated value of the external interference, and the estimated value is compensated to the cascade sliding mode law to obtain an anti-interference cascade sliding mode law; through the method of the present invention, the anti-interference ability and control accuracy of the electronic hydraulic braking system can be effectively improved, thereby improving the stability and safety of the system.

[0051] Furthermore, the specific implementation process of the embodiment of the present application is as follows:

[0052] The electronic hydraulic brake system is mainly divided into the motor torque to push rod displacement part and the push rod displacement to push rod hydraulic pressure part. First, the electronic control unit generates a target torque signal according to the braking demand and drives the motor to output the corresponding torque. The reduction mechanism receives the torque output by the motor and amplifies it and transmits it to the brake master cylinder push rod, thereby generating push rod displacement. Then, the push rod displacement is converted into actual hydraulic pressure through the brake master cylinder and the hydraulic part, acting on the brake system, and finally achieving the braking effect.

[0053] According to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and the simplified model includes the simplified model of the speed loop and the simplified model of the pressure loop; the simplified model is as follows: Figure 2 Here, the parameters of the electronic hydraulic brake system can be selected and adjusted according to specific usage requirements. The speed loop is the part from the motor torque to the push rod displacement. The simplified model of the speed loop is:

[0054]

[0055] Among them, m is the equivalent mass of the master cylinder push rod, c is the equivalent damping of the master cylinder push rod, k is the equivalent stiffness of the master cylinder push rod, and x is the displacement of the master cylinder push rod. is the first derivative of x, is the second-order derivative of x, T is the motor output torque, k1 is the ratio of the speed mechanism transmission ratio to the pinion radius, d x for the external interference;

[0056] The pressure ring is the part where the push rod moves to the push rod liquid pressure. The simplified model of the pressure ring is:

[0057]

[0058] in, is the first-order derivative of the actual hydraulic pressure P of the master cylinder, A is the piston area of ​​the brake chamber, V is the volume of the liquid in the brake chamber, K e is the bulk modulus, d P is the external interference.

[0059] In the embodiment of the present application, by simplifying the operating principle of the electronic hydraulic brake system under external interference into the motor torque to push rod displacement part and the push rod displacement to push rod hydraulic pressure part, and establishing the corresponding mathematical model, through the model establishment and parameter analysis of these two parts, it is possible to fully understand and predict the behavior of the electronic hydraulic brake system under external interference and unknown dynamics. This not only helps to optimize the control strategy, improve the response speed and accuracy of the system, but also enhances the anti-interference ability and stability of the system, and ensures the reliable operation of the brake system under complex working conditions. In addition, the established model provides a reliable theoretical basis for the subsequent control algorithm design and performance optimization, which helps to further improve the overall performance of the electronic hydraulic brake system and improve the braking safety and driving comfort of the vehicle.

[0060] Furthermore, we set the expected state P d =3Mpa, where P d is the expected value of the actual hydraulic pressure of the master cylinder; according to the expected state, the error function is obtained as follows:

[0061] e1=P-3;

[0062]

[0063] Among them, e1 is the actual hydraulic pressure error of the main cylinder, and e2 is the displacement speed error of the main cylinder push rod. The expected value of the master cylinder push rod displacement speed.

[0064] In the embodiment of the present application, by introducing the error function, the deviation between the current operating state and the expected state can be accurately evaluated, so that the control system can make targeted adjustments and compensations. This not only improves the control accuracy and response speed of the system, but also enhances the stability and reliability of the system under complex working conditions, ensuring the efficient and safe operation of the electronic hydraulic brake system.

[0065] Furthermore, according to the error function, the sliding surface function is obtained as follows:

[0066] s1=e1+λ 11 ∫e1dt;

[0067] s2=e2+λ 21 ∫e2dt;

[0068] Among them, s1 is the actual hydraulic pressure sliding surface of the main cylinder, s2 is the displacement speed sliding surface of the main cylinder push rod, and λ 11 and λ 21 are the controller parameters to be designed, and are all positive numbers, and t is the time.

[0069] In the embodiment of the present application, by designing the sliding surface function, the system state can be effectively guided to the sliding surface, thereby achieving rapid convergence of the error. This not only improves the dynamic response performance and anti-interference ability of the system, but also significantly improves the control accuracy and stability of the electronic hydraulic brake system, ensuring its reliable operation under various working conditions.

[0070] Further, according to the error function and the sliding surface function, the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law of the electronic hydraulic brake system are obtained; the speed loop cascade sliding mode control law is:

[0071]

[0072] The pressure loop cascade sliding mode control law is:

[0073]

[0074] Among them, λ 12 and λ 22 are the controller parameters to be designed, and they are all positive numbers.

[0075] In the embodiment of the present application, by introducing a cascade control structure, the present invention realizes coordinated control of multiple control variables in an electronic hydraulic brake system. Cascade control not only improves the stability of the system, but also effectively manages and adjusts the mutual influence between different variables under complex working conditions, ensuring the overall coordination and efficiency of the brake system. In addition, the sliding mode control technology significantly improves the control accuracy and response speed of the electronic hydraulic brake system. Sliding mode control can effectively deal with the nonlinearity and uncertainty problems of the system, making the adjustment of brake pressure faster and more accurate, thereby improving the braking performance of the vehicle and enhancing driving safety.

[0076] Furthermore, the external disturbance is estimated by using the speed loop composite disturbance observer and the pressure loop composite disturbance observer to obtain the external disturbance estimation value; the speed loop composite disturbance observer is:

[0077]

[0078] The pressure loop composite disturbance observer is:

[0079]

[0080] Among them, ζ1, ζ2, η1, η2, z1, z2, z3 and z4 are intermediate variables. are the first-order derivatives of z1, z2, z3, and z4 respectively, are the error function estimates of e1 and e2 respectively, They are The first-order derivative of , κ1, κ2, κ3, κ4, γ1, γ2, γ3 and γ4 are the parameters of the composite disturbance observer to be designed, and is the estimated value of the external interference.

[0081] In an embodiment of the present application, the composite disturbance observer can observe and estimate external disturbances in the system in real time. By timely acquiring and analyzing disturbance information, the system can quickly adjust the control strategy, significantly improving the anti-interference ability of the electronic hydraulic brake system under complex working conditions and ensuring the stability of the braking performance. In addition, an error prediction mechanism is added to the composite disturbance observer, which can predict and compensate for the impact of disturbances on the system in advance. This mechanism enables the system to respond before the disturbance occurs, significantly improving the control accuracy and response speed. Error prediction enables the control system to quickly and accurately adjust the brake pressure, improving the safety and stability of the system.

[0082] Further, the external disturbance estimation value is compensated to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law; the speed loop anti-interference cascade sliding mode control law is:

[0083]

[0084] The anti-interference cascade sliding mode control law of the pressure loop is:

[0085]

[0086] In the embodiment of the present application, by introducing an anti-interference compensation mechanism, the impact of external interference and unknown dynamics on the system can be effectively offset, which significantly improves the robustness and anti-interference ability of the system, thereby ensuring the stability and reliability of the electronic hydraulic braking system under various complex working conditions, and improving the overall control effect and safety performance of the system.

[0087] Embodiment 2

[0088] Figure 3The block diagram of the cascade control structure is shown, which includes two parts: the speed loop and the pressure loop. First, the pressure loop controller is responsible for adjusting the pressure of the hydraulic system to meet the preset target value. The control signal of the pressure loop is further transmitted to the motor torque to the push rod position part through the speed loop controller, which converts the motor torque into the displacement of the push rod, thereby adjusting the position of the push rod. The position of the push rod is further converted into hydraulic pressure output to achieve precise control of the system hydraulic pressure. The system is set up with a speed loop composite disturbance observer and a pressure loop composite disturbance observer, which are used to estimate the external disturbances in the speed loop and the pressure loop respectively. The disturbance observer feeds back the estimated disturbance signal to the corresponding controller, and improves the robustness and anti-interference performance of the entire system by compensating for external disturbances. The entire control system controls the movement speed of the push rod through the speed loop to ensure the precise control of the push rod displacement; while the pressure loop controls the final hydraulic pressure output, thereby achieving precise control and stable performance of the electronic hydraulic brake system. The combination of the cascade control structure and the composite disturbance observer can effectively deal with external disturbances and system uncertainties, and improve the control accuracy and stability of the system.

[0089] According to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established. The parameters of the electronic hydraulic brake system can be selected and adjusted according to specific usage requirements. The simplified model includes the simplified model of the speed loop and the simplified model of the pressure loop; the speed loop is the part from the motor torque to the push rod displacement, and the simplified model of the speed loop is:

[0090]

[0091] Among them, m is the equivalent mass of the master cylinder push rod, c is the equivalent damping of the master cylinder push rod, k is the equivalent stiffness of the master cylinder push rod, and x is the displacement of the master cylinder push rod. is the first derivative of x, is the second-order derivative of x, T is the motor output torque, k1 is the ratio of the speed mechanism transmission ratio to the pinion radius, d x for the external interference;

[0092] The pressure ring is the part where the push rod moves to the push rod liquid pressure. The simplified model of the pressure ring is:

[0093]

[0094] in, is the first-order derivative of the actual hydraulic pressure P of the master cylinder, A is the piston area of ​​the brake chamber, V is the volume of the liquid in the brake chamber, K e is the bulk modulus, d P is the external interference.

[0095] Furthermore, we set the expected state P d =3sint Mpa, where Pd is the expected value of the actual hydraulic pressure of the master cylinder; according to the expected state, the error function is obtained as follows:

[0096] e1 = P-3sint;

[0097]

[0098] Among them, e1 is the actual hydraulic pressure error of the main cylinder, and e2 is the displacement speed error of the main cylinder push rod. The expected value of the master cylinder push rod displacement speed.

[0099] Furthermore, according to the error function, the sliding surface function is obtained as follows:

[0100] s1=e1+λ 11 ∫e1dt;

[0101] s2=e2+λ 21 ∫e2dt;

[0102] Among them, s1 is the actual hydraulic pressure sliding surface of the main cylinder, s2 is the displacement speed sliding surface of the main cylinder push rod, and λ 11 and λ 21 are the controller parameters to be designed, and are all positive numbers, and t is the time.

[0103] Further, according to the error function and the sliding surface function, the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law of the electronic hydraulic brake system are obtained; the speed loop cascade sliding mode control law is:

[0104]

[0105] The pressure loop cascade sliding mode control law is:

[0106]

[0107] Among them, λ 12 and λ 22 are the controller parameters to be designed, and they are all positive numbers.

[0108] Furthermore, the external disturbance is estimated by using the speed loop composite disturbance observer and the pressure loop composite disturbance observer to obtain the external disturbance estimation value; the speed loop composite disturbance observer is:

[0109]

[0110] The pressure loop composite disturbance observer is:

[0111]

[0112] Among them, ζ1, ζ2, η1, η2, z1, z2, z3 and z4 are intermediate variables. are the first-order derivatives of z1, z2, z3, and z4 respectively, are the error function estimates of e1 and e2 respectively, They are The first-order derivative of , κ1, κ2, κ3, κ4, γ1, γ2, γ3 and γ4 are the parameters of the composite disturbance observer to be designed, and is the estimated value of the external interference.

[0113] Further, the external disturbance estimation value is compensated to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law; the speed loop anti-interference cascade sliding mode control law is:

[0114]

[0115] The anti-interference cascade sliding mode control law of the pressure loop is:

[0116]

[0117] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for controlling an electronic hydraulic brake system, characterized in that: The following steps are involved: S1. According to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and an expected state is set; the simplified model includes a simplified speed loop model and a simplified pressure loop model; S2. Obtaining an error function according to the simplified model of the velocity loop, the simplified model of the pressure loop and the desired state; According to the error function, a sliding surface function is obtained; S3, obtaining a speed loop cascade sliding mode control law and a pressure loop cascade sliding mode control law of the electronic hydraulic brake system according to the error function and the sliding surface function; S4. Use the speed loop composite disturbance observer and the pressure loop composite disturbance observer to estimate the external disturbance and obtain an external disturbance estimation value, and compensate the external disturbance estimation value to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law.

2. The electronic hydraulic brake system control method according to claim 1, characterized in that: According to the operating principle of the electronic hydraulic brake system, a simplified model of the electronic hydraulic brake system under external interference is established, and the simplified model includes the simplified model of the speed loop and the simplified model of the pressure loop; the speed loop is the part from the motor torque to the push rod displacement, and the simplified model of the speed loop is: Among them, m is the equivalent mass of the master cylinder push rod, c is the equivalent damping of the master cylinder push rod, k is the equivalent stiffness of the master cylinder push rod, and x is the displacement of the master cylinder push rod. is the first derivative of x, is the second-order derivative of x, T is the motor output torque, k1 is the ratio of the speed mechanism transmission ratio to the pinion radius, d x for the external interference; The pressure ring is the part where the push rod moves to the push rod liquid pressure. The simplified model of the pressure ring is: in, is the first-order derivative of the actual hydraulic pressure P of the master cylinder, A is the piston area of ​​the brake chamber, V is the volume of the liquid in the brake chamber, K e is the bulk modulus, d P is the external interference.

3. The electronic hydraulic brake system control method according to claim 2, characterized in that: Set the desired state P d , where P d is the expected value of the actual hydraulic pressure of the master cylinder; according to the expected state, the error function is obtained as follows: e1=PP d ; Among them, e1 is the actual hydraulic pressure error of the main cylinder, and e2 is the displacement speed error of the main cylinder push rod. The expected value of the master cylinder push rod displacement speed.

4. The electronic hydraulic brake system control method according to claim 3, characterized in that: According to the error function, the sliding surface function is obtained as follows: s1=e1+λ 11 ∫e1dt; s2=e2+λ 21 ∫e2dt; Among them, s1 is the sliding surface of the actual hydraulic pressure of the main cylinder, s2 is the sliding surface of the displacement speed of the main cylinder push rod, and λ 11 and λ 21 are the controller parameters to be designed, and are all positive numbers, and t is the time.

5. The electronic hydraulic brake system control method according to claim 1, characterized in that: According to the error function and the sliding surface function, the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law of the electronic hydraulic brake system are obtained; the speed loop cascade sliding mode control law is: The pressure loop cascade sliding mode control law is: Among them, λ 12 and λ 22 are the controller parameters to be designed, and they are all positive numbers.

6. The electronic hydraulic brake system control method according to claim 1, characterized in that: The external disturbance is estimated by using the speed loop composite disturbance observer and the pressure loop composite disturbance observer to obtain the external disturbance estimation value; the speed loop composite disturbance observer is: The pressure loop composite disturbance observer is: Among them, ζ1, ζ2, η1, η2, z1, z2, z3 and z4 are intermediate variables. are the first-order derivatives of z1, z2, z3, and z4 respectively, are the error function estimates of e1 and e2 respectively, They are The first-order derivative of , κ1, κ2, κ3, κ4, γ1, γ2, γ3 and γ4 are the parameters of the composite disturbance observer to be designed, and is the estimated value of the external interference.

7. The electronic hydraulic brake system control method according to claim 1, characterized in that: The external disturbance estimation value is compensated to the speed loop cascade sliding mode control law and the pressure loop cascade sliding mode control law to obtain the speed loop anti-interference cascade sliding mode control law and the pressure loop anti-interference cascade sliding mode control law; the speed loop anti-interference cascade sliding mode control law is: The anti-interference cascade sliding mode control law of the pressure loop is:

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