Fully decoupled brake-by-wire method and system

Abstract

The present application relates to a fully decoupled brake-by-wire method and system, which is applied to the field of brake-by-wire technology. The method includes: detecting whether the brake-by-wire system is powered on normally; if it is not powered on normally or there is a fault after normal power-on, entering a mechanical backup braking mode; if it is powered on normally and there is no fault, detecting whether the brake-by-wire system is in a pedal-powered state; if not, entering a normal brake-by-wire mode; if so, determining whether the stroke of a mechanical push rod at the moment of power-on is greater than a first stroke value; if not, entering a normal brake-by-wire mode; if so, entering a pedal-powered braking mode, controlling the analog cylinder circuit isolation valve to remain closed, controlling the manual cylinder circuit isolation valve to change from an open state to a closed state after power is applied, and determining a target brake pressure based on the stroke of the mechanical push rod and the pressure detected by the manual cylinder pressure sensor. This ensures the output of brake pressure while taking into account brake pedal feel.

Description

Technical Field

[0001] The present application relates to the technical field of wire-controlled braking, and in particular to a fully decoupled wire-controlled braking method and system. Background Art

[0002] In vehicles equipped with a brake-by-wire system, when the driver presses the brake pedal and powers on, the brake-by-wire system switches from mechanical backup braking mode to normal brake-by-wire mode. For a fully decoupled brake-by-wire system, if normal brake-by-wire mode is entered directly upon pressing the brake pedal and powering on, the simulated cylinder circuit isolation valve, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve will be energized. Because the simulated cylinder is pressure-free before the simulated cylinder circuit isolation valve opens, while the manual cylinder chamber contains hydraulic pressure, a significant portion of the fluid volume in the manual cylinder chamber is transferred to the simulated cylinder at the moment the simulated cylinder circuit isolation valve opens to balance the hydraulic pressure. This can cause the brake pedal to momentarily sink. Furthermore, the deeper the brake pedal is pressed when power is applied, the more pronounced the sinking, and the worse the brake pedal feel for the driver. Summary of the Invention

[0003] In order to solve the above technical problems, the present application provides a fully decoupled wire-controlled braking method, system and storage medium.

[0004] According to a first aspect of the present application, a fully decoupled brake-by-wire method is provided, which is applied to a brake-by-wire system. The method comprises:

[0005] Check whether the brake-by-wire system is powered on normally;

[0006] If the wire control brake system is not powered on normally, the system enters the mechanical backup brake mode;

[0007] If the brake-by-wire system is powered on normally, detecting whether the brake-by-wire system has a fault;

[0008] If there is a fault in the brake-by-wire system, a mechanical backup braking mode is entered;

[0009] If there is no fault in the brake-by-wire system, detecting whether the brake-by-wire system is in a pedal-powered state;

[0010] If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered;

[0011] If the brake-by-wire system is in a pedal-powered state, determining whether the stroke of the mechanical push rod at the moment of power-on is greater than a first stroke value;

[0012] If the stroke of the mechanical push rod is less than or equal to the first stroke value, entering the normal wire control brake mode;

[0013] If the stroke of the mechanical push rod is greater than the first stroke value, entering the pedal-powered braking mode;

[0014] In the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is applied, and a first target brake pressure is determined according to the stroke of the mechanical push rod; a second target brake pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target brake pressure and the second target brake pressure is selected as the target brake pressure, and the target brake pressure is output;

[0015] detecting whether the brake-by-wire system is powered off;

[0016] If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault;

[0017] If it is detected that the brake-by-wire system is powered off, the process ends.

[0018] Optionally, the method further includes:

[0019] When the wire control brake system is in the pedal-operated electric braking mode, the stroke of the mechanical push rod is detected. If the stroke of the mechanical push rod is less than a second stroke value, the normal wire control brake mode is entered, wherein the second stroke value is less than the first stroke value.

[0020] Optionally, before detecting whether the brake-by-wire system is in a pedaling power-on state, the method further includes:

[0021] If the vehicle is equipped with an electronic parking brake system, check whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched since power was applied;

[0022] If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched, then executing the step of detecting whether the brake-by-wire system is in the pedal-on state;

[0023] If the electronic parking brake system is in the applied state and its state has not been switched before, it enters the mechanical backup brake mode.

[0024] Optionally, the method further includes:

[0025] If the vehicle is detected to be slipping in the pedal-operated power-on braking mode, the target brake pressure is increased according to the set gradient control based on the slipping state, wherein the increased target brake pressure is not greater than the maximum brake pressure limit value when the vehicle is in motion;

[0026] After detecting that the vehicle has stopped slipping, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is stationary before slipping, the increased target brake pressure will be reduced to the maximum brake pressure limit value according to the set descent gradient, and when the stroke of the mechanical push rod is less than the second stroke value, the normal wire control braking mode will be entered.

[0027] Optionally, detecting whether the brake-by-wire system is in a pedal-powered state includes:

[0028] If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state;

[0029] When the brake-by-wire system is in a pedal-on state, and only when it is detected that the brake pedal is fully released, exiting the pedal-on state;

[0030] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0031] Optionally, after entering the mechanical backup braking mode, the method further includes:

[0032] The manual cylinder circuit isolation valve is kept open, while the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are kept closed. This ensures communication between the two piston chambers of the manual cylinder and the electronic stability control system and the wheel-mounted brake circuit. When the brake pedal is depressed and pressure is built up, the pressure in the connected brake circuits builds normally and remains above zero. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is zero, and the pressure before the servo cylinder circuit isolation valve and within the servo cylinder is also zero.

[0033] Optionally, after entering the normal brake-by-wire mode, the method further includes:

[0034] The manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state, and the pressure in the manual cylinder and the simulation cylinder is measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side are measured by the servo cylinder pressure sensor.

[0035] According to a second aspect of the present application, a fully decoupled brake-by-wire system is provided, comprising: a controller, a brake pedal, a mechanical push rod, a travel sensor, a fluid reservoir, a manual cylinder including a piston and a spring, a manual cylinder pressure sensor, a manual cylinder circuit isolation valve, a simulation cylinder circuit isolation valve, a simulation cylinder, a servo cylinder circuit isolation valve, a servo cylinder pressure sensor, a servo cylinder body, a servo cylinder piston, a ball screw transmission mechanism, and a servo motor;

[0036] The controller is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system has a fault; if the brake-by-wire system has a fault, enter a mechanical backup braking mode; if the brake-by-wire system has no fault, detect whether the brake-by-wire system is in a pedal-powered state; and,

[0037] If the brake-by-wire system is not in the pedal-powered state, it enters the normal brake-by-wire mode; if the brake-by-wire system is in the pedal-powered state, it determines whether the stroke of the mechanical push rod at the moment of power-on is greater than the first stroke value; if the stroke of the mechanical push rod is less than or equal to the first stroke value, it enters the normal brake-by-wire mode; if the stroke of the mechanical push rod is greater than the first stroke value, it enters the pedal-powered braking mode; in the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in the closed state, and the manual cylinder circuit isolation valve is controlled to change from the open state to the closed state after power is applied.

[0038] Determining a first target brake pressure according to the stroke of the mechanical push rod; determining a second target brake pressure according to the pressure detected by the manual cylinder pressure sensor, selecting the larger value of the first target brake pressure and the second target brake pressure as the target brake pressure, and outputting the target brake pressure;

[0039] detecting whether the brake-by-wire system is powered off;

[0040] If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault;

[0041] If it is detected that the brake-by-wire system is powered off, the process ends.

[0042] Optionally, the controller is further used to detect the stroke of the mechanical push rod when the wire control braking system is in the pedal-operated electric braking mode, and enter the normal wire control braking mode if the stroke of the mechanical push rod is less than a second stroke value, wherein the second stroke value is less than the first stroke value.

[0043] Optionally, the controller is further used to detect whether the electronic parking brake system is in the powered-on state before detecting whether the electronic parking brake system is in the powered-on state with the pedal pressed, if the vehicle is equipped with an electronic parking brake system; if the electronic parking brake system is in the unpowered state, or the electronic parking brake system is in the powered-on state and its state has been switched, then the step of detecting whether the electronic parking brake system is in the powered-on state with the pedal pressed is performed; if the electronic parking brake system is in the powered-on state and its state has not been switched, then the mechanical backup braking mode is entered.

[0044] Optionally, the controller is also used to detect whether slipping occurs. If slipping is detected in the pedal-operated electric braking mode, the target brake pressure is increased according to the slipping state according to a set increasing gradient control, wherein the increased target brake pressure is not greater than the maximum allowable working pressure of the wire control brake system; after detecting that the slipping stops, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is stationary before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to a set decreasing gradient, and when the stroke of the mechanical push rod is less than the second stroke value, the normal wire control brake mode is entered.

[0045] Optionally, the controller detects whether the brake-by-wire system is in a pedal-powered state by the following steps:

[0046] If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state;

[0047] When the brake-by-wire system is in a pedal-on state, the pedal-on state is exited only when the brake pedal is fully released;

[0048] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0049] Optionally, the controller is also used to control the manual cylinder circuit isolation valve to remain open, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain closed after entering the mechanical backup braking mode, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side braking circuit. When the brake pedal is stepped on to build pressure, the connected brake circuit pressure is established normally, and the pressure is greater than 0, the circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0050] Optionally, the controller is also used to control the manual cylinder circuit isolation valve to change from an open state to a closed state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to change from a closed state to an open state after entering the normal wire control braking mode, and measure the pressure in the manual cylinder and the simulation cylinder through the manual cylinder pressure sensor, and measure the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side through the servo cylinder pressure sensor.

[0051] According to a third aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method described in the first aspect is implemented.

[0052] According to a fourth aspect of the present application, a computer program product is provided. When the computer program product is run on a computer, the computer is caused to execute the method described in the first aspect.

[0053] The technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0054] When the brake-by-wire system is powered on normally, presents no faults, and is in the pedal-powered state, the system determines whether to enter pedal-powered braking mode or normal brake-by-wire mode by determining the stroke of the mechanical push rod. If the stroke of the mechanical push rod is greater than a first stroke value, the system enters pedal-powered braking mode. In pedal-powered braking mode, the analog cylinder circuit isolation valve remains closed, while the manual cylinder circuit isolation valve switches from an open state to a closed state upon powering on. This isolates the brake fluid in the manual cylinder from the analog cylinder circuit isolation valve and the manual cylinder circuit isolation valve, preventing the pedal from suddenly sinking when the brake pedal is deeply depressed. Furthermore, if the brake pedal cannot be depressed further, the target pressure is determined based on the stroke of the mechanical push rod and the pressure detected by the manual cylinder pressure sensor to ensure brake pressure output and prevent the vehicle from rolling after the brake pedal is depressed and released from parking on a slope. If the stroke of the mechanical push rod is less than or equal to the first stroke value, the vehicle directly enters normal brake-by-wire mode. At this point, there will be no noticeable pedal sinking that the driver will notice. Furthermore, because the vehicle is in normal brake-by-wire mode, subsequent braking with the brake pedal will not experience any abnormal brake pedal feel. This shows that the embodiment of the present application prioritizes brake pressure output, ensuring both safety and a good brake pedal feel, thus ensuring a positive driver experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0056] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0057] Figure 1 A schematic diagram of a fully decoupled brake-by-wire system in an embodiment of the present application;

[0058] Figure 2 A flow chart of a fully decoupled brake-by-wire method in an embodiment of the present application;

[0059] Figure 3 A schematic diagram of a fully decoupled brake-by-wire system in mechanical backup braking mode;

[0060] Figure 4 A schematic diagram of a fully decoupled brake-by-wire system in normal brake-by-wire mode;

[0061] Figure 5 This is an illustration of the data results after switching from mechanical backup braking mode to normal wire control braking mode;

[0062] Figure 6 This is another flow chart of the fully decoupled brake-by-wire method in the embodiment of the present application;

[0063] Figure 7 This is another flow chart of the fully decoupled brake-by-wire method in the embodiment of the present application;

[0064] Figure 8 Schematic diagram of the structure of a fully decoupled wire-controlled brake system in an embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to more clearly understand the above-mentioned objectives, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0066] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application can also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, not all of the embodiments.

[0067] The brake-by-wire system of the embodiment of the present application is a fully decoupled brake-by-wire system (DBS, Decoupled Brake System). Because of the isolation of the solenoid valve, it can achieve a fully decoupled state, that is, the pedal feel will not be affected by the execution circuit at all, and the pedal depression depth and the final output hydraulic pressure can be completely decoupled in the corresponding relationship. Therefore, it is convenient to perform many complex and intelligent control logics.

[0068] See also Figure 1 , Figure 1 This is a schematic diagram of the principle of a fully decoupled, wire-controlled brake system in an embodiment of the present application. The wire-controlled brake system includes: a brake pedal 1, a mechanical push rod 2, a travel sensor 3, a fluid reservoir 4, a first piston and spring 5 in the manual cylinder, a second piston and spring 6 in the manual cylinder, a manual cylinder pressure sensor 7, a manual cylinder circuit isolation valve 8, a manual cylinder circuit isolation valve 9, a simulation cylinder circuit isolation valve 10, a simulation cylinder 11, a servo cylinder circuit isolation valve 12, a servo cylinder circuit isolation valve 13, a servo cylinder pressure sensor 14, a servo cylinder body 15, a servo cylinder piston 16, a ball screw drive mechanism 17, and a servo motor 18. The remaining components are the brake fluid circuit and the associated filter and one-way valve. The circuit is filled with brake fluid, and the fluid level in the fluid reservoir 4 is between the minimum and maximum positions. The manual cylinder circuit isolation valves 8 and 9 are both normally open valves, while the simulation cylinder circuit isolation valves 10, the servo cylinder circuit isolation valves 12, and the servo cylinder circuit isolation valves 13 are all normally closed valves.

[0069] Figure 1 In the car, the Electronic Stability Control (ESC) connects to the two circuits of the DBS and to the four wheel brakes. The symbols FL, FR, RL, and RR in the figure represent the four wheel brakes, respectively.

[0070] See also Figure 2 , Figure 2 This is a flow chart of a fully decoupled brake-by-wire method according to an embodiment of the present application, which is applied to a brake-by-wire system and may include the following steps:

[0071] Step S202 , detecting whether the brake-by-wire system is powered on normally.

[0072] If the brake-by-wire system is not powered on normally, step S204 is executed; if the brake-by-wire system is powered on normally, step S206 is executed.

[0073] Step S204: Entering the mechanical backup braking mode.

[0074] In mechanical backup braking mode, no control strategy is involved. If the brake-by-wire system is not powered on properly, manual cylinder circuit isolation valves 8 and 9 are controlled to remain open, while analog cylinder circuit isolation valves 10, servo cylinder circuit isolation valves 12, and servo cylinder circuit isolation valves 13 are controlled to remain closed.

[0075] Combine Figure 3 In the mechanical backup braking mode, the brake pedal 1 is depressed, pushing the mechanical push rod 2 to the left. At this time, the piston in the manual cylinder moves to the left, and the piston spring is compressed. After the piston in the manual cylinder moves to the left, it passes the brake fluid circuit inlet of the two piston chambers in the manual cylinder. The brake fluid in the two piston chambers of the manual cylinder is sealed and compressed, and the further the piston is pushed to the left, the higher the pressure in the sealed circuit. At this time, since the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are in the open state, the brake circuit from the two piston chambers of the manual cylinder to the electronic stability control system and the wheel side is connected. When the brake pedal is depressed to build pressure, the pressure of the connected brake circuit is built up normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0076] Step S206 , detecting whether there is a fault in the brake-by-wire system.

[0077] In this embodiment of the present application, a fault in the brake-by-wire system can be determined by detecting whether the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve are faulty. If none of the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve are faulty, the brake-by-wire system is determined to be faulty. If at least one of the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve is faulty, the brake-by-wire system is determined to be faulty.

[0078] If there is a fault in the wire control braking system, step S204 is executed. At this time, the motor and all solenoid valves (manual cylinder circuit isolation valve 8, manual cylinder circuit isolation valve 9, simulation cylinder circuit isolation valve 10, servo cylinder circuit isolation valve 12 and servo cylinder circuit isolation valve 13) are not controlled; if there is no fault in the wire control braking system, step S208 is executed.

[0079] Step S208 , detecting whether the brake-by-wire system is in a pedal-powered state.

[0080] After the brake pedal is pressed and the system is powered on, as long as the driver has not completely released the brake pedal, the brake-by-wire system is considered to be in the pedal-on state. In other words, if the controller detects that the brake pedal is pressed at the moment the brake-by-wire system is powered on, the brake-by-wire system is determined to be in the pedal-on state. Conversely, if the controller detects that the brake pedal is not pressed at the moment the brake-by-wire system is powered on, the brake-by-wire system is determined to be not in the pedal-on state.

[0081] As long as the brake-by-wire system is identified as being in the pedal-on state at the moment it is powered on, if the exit condition is never met, the system is still considered to be in the pedal-on state.

[0082] If the brake-by-wire system is not in the pedal-on state, step S210 is executed, i.e., the system enters the normal brake-by-wire mode. All subsequent braking operations are in the normal brake-by-wire mode. If the brake-by-wire system is in the pedal-on state, step S212 is executed.

[0083] Step S210, entering normal brake-by-wire mode.

[0084] Combine Figure 4 After entering the normal wire control braking mode, all solenoid valves are energized and activated, that is, the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state. The pressure in the manual cylinder and the simulation cylinder can be measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side can be measured by the servo cylinder pressure sensor.

[0085] When the brake pedal is depressed, human-generated hydraulic pressure builds up before the manual cylinder circuit isolation valves 8 and 9. At this point, the pressure measured by the manual cylinder pressure sensor 7 represents the pressure in the manual cylinder and the simulated cylinder. Furthermore, the pressure generated by the servo motor 18 driving the ball screw drive mechanism 17 forward to compress the brake fluid in the servo cylinder piston 16 builds up in the fluid circuit after the manual cylinder circuit isolation valves 8 and 9. At this point, the pressure measured by the servo cylinder pressure sensor 14 represents the pressure in the hydraulic circuits before and after the servo cylinder body 15, the servo cylinder circuit isolation valves 12 and 13, and the pressure in the ESC and wheel side.

[0086] Step S212: determining whether the stroke of the mechanical push rod at the moment of power-on is greater than a first stroke value.

[0087] In the embodiment of the present application, the brake-by-wire system is tested on a bench when switching from the mechanical backup braking mode to the normal brake-by-wire mode. The data results obtained can be seen in Figure 5The horizontal axis represents the stroke value of the mechanical push rod at the moment the pedal is pressed and the power is turned on, that is, the value collected by the stroke sensor 3.

[0088] The manual cylinder pressure in the curve refers to the value collected by the manual cylinder pressure sensor 7 at the moment the pedal is stepped on and the power is turned on.

[0089] The pedal force change value in the curve refers to the difference calculated based on the values ​​collected at different times by the external pedal force sensor. That is, the value obtained by collecting the pedal force value at the moment the brake pedal 1 is powered on and the lowest value within 0.5 seconds thereafter is calculated. The difference between the two values ​​can be used to intuitively reflect the change in pedal force after the brake pedal is powered on.

[0090] The manual cylinder pressure change value in the curve refers to the difference calculated based on the values ​​collected by the manual cylinder pressure sensor 7 at different times, that is, the pressure value at the moment the brake pedal 1 is powered on and the lowest pressure value within 0.5s thereafter. The value obtained by taking the difference between the two can reflect the manual cylinder pressure changes at the moment the brake pedal is powered on and thereafter.

[0091] The mechanical push rod stroke change value in the curve refers to the difference calculated from the values ​​collected by the stroke sensor 3 at different times, that is, the stroke value at the moment the brake pedal 1 is powered on and the lowest stroke value within 0.5 seconds thereafter. The value obtained by taking the difference between the two can intuitively reflect the severity of the pedal sinking when the brake pedal is powered on.

[0092] It can be seen that when the brake pedal is powered on, the shallower the brake pedal is depressed (for example, less than or equal to S2), the smaller the pedal force and the mechanical push rod stroke (or pedal stroke) will change, and the smaller the instantaneous pressure drop when simulating the cylinder balance pressure (that is, the smaller the change value of the manual cylinder pressure is), which will hardly cause the pedal to sink, or the sinking caused will be very small, not enough to cause the driver to feel uncomfortable.

[0093] The specific analysis process is as follows: in the mechanical backup braking mode, when the brake pedal is depressed shallowly (for example, less than or equal to S2), there is a certain small pressure in the braking system. When the power is turned on at this time, the simulation cylinder circuit isolation valve 10 is opened, and the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed. The simulation cylinder 11 part needs to balance the pressure, but because the pressure of the braking system itself is small, the piston of the simulation cylinder 11 does not need to move too much, so the pressure changes transmitted to the manual cylinder, the changes in the stroke transmitted to the mechanical push rod and the changes in the pedal force will be very small, so it will not cause discomfort to the driver.

[0094] When the brake pedal is powered on, the deeper the pedal is depressed (for example, greater than S2), the greater the change in pedal force and mechanical push rod stroke (or pedal stroke), the greater the instantaneous pressure drop when simulating cylinder balance pressure (that is, the greater the change in manual cylinder pressure), causing greater pedal sinking and a worse experience.

[0095] The specific analysis process is as follows: when the brake pedal is depressed deeper in the mechanical backup braking mode (for example, greater than S2), there is a large pressure in the braking system. When the power is turned on at this time, the simulation cylinder circuit isolation valve 10 opens, and the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed. The simulation cylinder 11 part needs to balance the pressure, but because the braking system pressure itself is relatively high, the simulation cylinder 11 piston needs to move a large stroke in a short time, so the pressure changes transmitted to the manual cylinder, the stroke changes transmitted to the mechanical push rod and the changes in the pedal force will be large, which will cause discomfort to the driver.

[0096] Based on the above analysis, the present embodiment can determine whether the vehicle is in pedal-operated braking mode or normal brake-by-wire mode by determining the stroke of the mechanical push rod. If the stroke of the mechanical push rod is less than or equal to the first stroke value (i.e., S2), step S210 is executed, directly entering normal brake-by-wire mode. At this time, there will be no obvious pedal sinking that the driver will notice. Because the vehicle is in normal brake-by-wire mode, subsequent braking with pedal operation will not produce any abnormal brake pedal feel. If the stroke of the mechanical push rod is greater than the first stroke value, step S214 is executed.

[0097] Step S214, entering the pedal-powered braking mode.

[0098] In the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in the closed state, and the manual cylinder circuit isolation valve is controlled to change from the open state to the closed state after power is applied. The first target braking pressure is determined according to the stroke of the mechanical push rod; the second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the target braking pressure is output.

[0099] In this mode, the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed at the moment the brake pedal is powered on, and the simulation cylinder circuit isolation valve 10 is kept closed. In this way, the brake fluid in the manual cylinder will be isolated from the circuits after the simulation cylinder circuit isolation valve 10 and after the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9, thereby preventing the pedal from suddenly sinking when the brake pedal is powered on when it is deeply depressed.

[0100] Although the brake pedal cannot be depressed any further after the manual cylinder circuit isolation valve 8, the manual cylinder circuit isolation valve 9 and the simulation cylinder circuit isolation valve 10 are closed, if the force of pressing the brake pedal 1 is further increased, the measurement value of the manual cylinder pressure sensor 7 will increase further. The increase in this value will be used as a control basis to increase the target pressure of the braking system, thereby generating a greater braking pressure at the wheel side to meet the braking requirements.

[0101] For example, when the driver applies power by pressing the brake pedal deeply (i.e., the stroke of the mechanical push rod is much greater than S2), the system enters the pedal-on-power-brake mode. At this point, the target brake pressure is already high enough to prevent the vehicle from rolling down a slope after pressing the pedal and releasing the parking brake. When the driver applies power by pressing the brake pedal lightly (i.e., the stroke of the mechanical push rod is slightly greater than S2), the system enters the pedal-on-power-brake mode. Further increasing the force applied to the brake pedal increases the target pressure of the brake system based on the value measured by the manual cylinder pressure sensor 7, ensuring that the vehicle does not roll down a slope after pressing the pedal and releasing the parking brake on a slope.

[0102] Step S216 , detecting whether the brake-by-wire system is powered off.

[0103] If it is detected that the brake-by-wire system is not powered off, the process returns to step S206 , ie, the above process is executed in a loop; if it is detected that the brake-by-wire system is powered off, the process ends.

[0104] The fully decoupled brake-by-wire method of the present application, when power is applied by stepping on the brake pedal, determines whether to enter pedal-powered braking mode or normal brake-by-wire mode by determining the stroke of the mechanical push rod. If the stroke of the mechanical push rod is greater than a first stroke value, the brake-powered braking mode is entered. In pedal-powered braking mode, the analog cylinder circuit isolation valve remains closed, while the manual cylinder circuit isolation valve changes from an open state to a closed state after power is applied. This isolates the brake fluid in the manual cylinder from the circuits after the analog cylinder circuit isolation valve and the manual cylinder circuit isolation valve, thereby preventing the pedal from suddenly sinking when power is applied by deeply pressing the brake pedal. Furthermore, if the brake pedal cannot be further pressed, the target brake pressure is determined based on the stroke of the mechanical push rod and the pressure measured by the manual cylinder pressure sensor to adjust the brake pressure and ensure the output of the brake pressure. This prevents the vehicle from rolling after powering on and releasing the parking brake on a slope. If the stroke of the mechanical push rod is less than or equal to the first stroke value, the vehicle directly enters normal brake-by-wire mode. At this point, there will be no noticeable pedal sinking that the driver will notice. Furthermore, because the vehicle is in normal brake-by-wire mode, subsequent braking with the brake pedal will not experience any abnormal brake pedal feel. This shows that the embodiment of the present application prioritizes brake pressure output, ensuring both safety and a good brake pedal feel, thus ensuring a superior driver experience.

[0105] In the pedal-operated braking mode, if the brake pedal is slightly released but not completely released, the vehicle may slip on a slope due to the reduction in the target pressure of the braking system. At this time, it is necessary to continue to press the pedal to increase the braking pressure. However, because it is in the pedal-operated braking mode, the brake pedal cannot be continued to be pressed after it has been released to the point where it is not completely released, which may cause a poor experience.

[0106] To avoid this problem, in the pedal-powered braking mode, if the conditions for entering the normal wire-controlled braking mode are not met (i.e., the mechanical push rod stroke in the pedal-powered braking mode is not less than S1), the highest target braking pressure in this mode will always be maintained (this highest target braking pressure will be subject to a maximum value limit, i.e., it will not exceed the in-situ maximum braking pressure limit value) until the mechanical push rod stroke is less than S1 and the target braking pressure is released to 0. Subsequent braking will enter the normal wire-controlled braking mode, and the highest target pressure maintenance logic of the pedal-powered braking mode will no longer be executed.

[0107] See also Figure 6 ,exist Figure 2 Based on the embodiment, the following steps may also be included:

[0108] Step S2151 , when the brake-by-wire system is in the pedal-operated power-on braking mode, the stroke of the mechanical push rod is detected.

[0109] Step S2152: Determine whether the stroke of the mechanical push rod is less than a second stroke value, wherein the second stroke value is less than the first stroke value.

[0110] If the stroke of the mechanical push rod is less than the second stroke value (ie, S1), step S210 is executed, that is, the electric braking mode is switched from the pedal-on braking mode to the normal wire control braking mode. If the stroke of the mechanical push rod is greater than or equal to the second stroke value, step S216 is executed.

[0111] Considering that the driver may release the brake pedal slightly (not completely) and then continue to press it quickly in the pedal-powered braking mode, if the corresponding solenoid valve control (manual cylinder circuit isolation valve 8 and manual cylinder circuit isolation valve 9 are energized to close, and analog cylinder circuit isolation valve 10 is energized to open) is not fast enough when switching from the pedal-powered braking mode to the normal wire-controlled braking mode, it will still cause a slight lag when the brake pedal is quickly pressed. By designing the threshold for entering the pedal-powered braking mode to be the first stroke value and the threshold for exiting the pedal-powered braking mode to be the second stroke value, abnormal pedal feel can be avoided and normal wire-controlled braking mode can be entered more quickly.

[0112] Optionally, if slipping is detected in the pedal-operated electric braking mode, the target brake pressure is increased according to the set increase gradient control based on the slipping state. The increased target brake pressure is not limited by the maximum brake pressure of the vehicle in a stationary state before slipping, but is limited by the maximum allowable operating pressure of the DBS system, that is, the increased target brake pressure is not greater than the maximum allowable operating pressure of the brake-by-wire system. After the slipping is detected to stop, if the increased target brake pressure is less than or equal to the maximum brake pressure limit value of the vehicle in a stationary state before slipping, the increased target brake pressure is maintained. If the increased target brake pressure is greater than the maximum brake pressure limit value of the vehicle in a stationary state before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to the set decrease gradient, and when the stroke of the mechanical push rod is less than the second stroke value, the pedal-operated electric braking mode is exited and the normal brake-by-wire mode is entered, which can help the driver prevent the vehicle from slipping when starting on a slope.

[0113] See also Figure 7 , Figure 7 This is another flow chart of the fully decoupled wire control brake method in the embodiment of the present application. Figure 2 Based on the embodiment, the following steps may also be included:

[0114] Step S207 : If the vehicle is equipped with an electronic parking brake system, it is detected whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched after power-on.

[0115] If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched before, execute step S208; if the electronic parking brake system is in the applied state and its state has not been switched before, execute step S204, i.e. enter the mechanical backup brake mode.

[0116] For vehicles equipped with an electronic parking brake system, if the system is in the applied state when the brake pedal is pressed and the power is on, and the system's state has not changed since power was applied, the logic of the mechanical backup braking mode can be maintained. If the system is not applied, or if the system is applied but its state has changed (for example, the system has switched from "applied-released-applied" to "applied" while the brake pedal is pressed and the power is on), the system will switch to the pedal-pressed braking mode. This can avoid the problem of sudden pedal sinking and prevent the vehicle from rolling away due to insufficient brake pressure.

[0117] It should be noted that although the steps of the method of the present application are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0118] The present application also provides a fully decoupled wire-controlled brake system. Figure 8 The brake-by-wire system 800 includes a controller 802, a brake pedal 804, a mechanical push rod 806, a travel sensor 808, a fluid reservoir 810, a manual cylinder 812 including a piston and a spring, a manual cylinder pressure sensor 814, a manual cylinder circuit isolation valve 816, a simulation cylinder circuit isolation valve 818, a simulation cylinder 820, a servo cylinder circuit isolation valve 822, a servo cylinder pressure sensor 824, a servo cylinder body 826, a servo cylinder piston 828, a ball screw transmission mechanism 830, and a servo motor 832.

[0119] Controller 802 is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system is faulty; if the brake-by-wire system is faulty, enter a mechanical backup braking mode; if the brake-by-wire system is not faulty, detect whether the brake-by-wire system is in a pedal-powered state; and,

[0120] If the brake-by-wire system is not in the pedal-powered state, it enters the normal brake-by-wire mode; if the brake-by-wire system is in the pedal-powered state, it determines whether the stroke of the mechanical push rod at the moment of power-on is greater than the first stroke value; if the stroke of the mechanical push rod is less than or equal to the first stroke value, it enters the normal brake-by-wire mode; if the stroke of the mechanical push rod is greater than the first stroke value, it enters the pedal-powered braking mode; in the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in the closed state, and the manual cylinder circuit isolation valve is controlled to change from the open state to the closed state after power is supplied, and the first target braking pressure is determined according to the stroke of the mechanical push rod; the second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the target braking pressure is output; and,

[0121] Checking whether the brake-by-wire system is powered off; if it is detected that the brake-by-wire system is not powered off, returning to the step of checking whether the brake-by-wire system is faulty;

[0122] If it is detected that the brake-by-wire system is powered off, the process ends.

[0123] Optionally, the controller 802 is further used to detect the stroke of the mechanical push rod when the wire control braking system is in the pedal-operated braking mode, and enter the normal wire control braking mode if the stroke of the mechanical push rod is less than a second stroke value, wherein the second stroke value is less than the first stroke value.

[0124] Optionally, the controller 802 is also used to detect whether the electronic parking brake system is in the pedal-powered state before detecting whether the electronic parking brake system is in the pedal-powered state, if the vehicle is equipped with an electronic parking brake system, whether the electronic parking brake system is in the pulled-up state, and whether the state of the electronic parking brake system has switched after power-on; if the electronic parking brake system is in the unpulled state, or the electronic parking brake system is in the pulled-up state and its state has been switched, then the step of detecting whether the electronic parking brake system is in the pedal-powered state is executed; if the electronic parking brake system is in the pulled-up state and its state has not been switched, then the mechanical backup braking mode is entered.

[0125] Optionally, the controller 802 is also used to detect whether slipping occurs. If slipping is detected in the pedal-operated electric braking mode, the target brake pressure is increased according to the slipping state according to a set increasing gradient control, wherein the increased target brake pressure is not greater than the maximum allowable working pressure of the wire control brake system; after detecting that the slipping stops, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is in a stationary state before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to a set decreasing gradient, and when the stroke of the mechanical push rod is less than the second stroke value, the normal wire control brake mode is entered.

[0126] Optionally, the controller 802 detects whether the brake-by-wire system is in the pedal-on state by the following steps:

[0127] If the brake pedal is detected to be depressed at the moment of power-on, it is determined that the brake-by-wire system is in the pedal-on state;

[0128] When the brake-by-wire system is in the pedal-on state, it will exit the pedal-on state only when the brake pedal is fully released;

[0129] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0130] Optionally, after entering the mechanical backup braking mode, the controller 802 is also used to control the manual cylinder circuit isolation valve to remain open, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain closed, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side braking circuit. When the brake pedal is stepped on to build pressure, the connected braking circuit pressure is established normally, and the pressure is greater than 0, the circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0131] Optionally, the controller 802 is also used to control the manual cylinder circuit isolation valve to change from an open state to a closed state, control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to change from a closed state to an open state after entering the normal wire control braking mode, and measure the pressure in the manual cylinder and the simulation cylinder through the manual cylinder pressure sensor, and measure the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side through the servo cylinder pressure sensor.

[0132] The specific details of each module or unit in the above device have been described in detail in the corresponding method, so they will not be repeated here.

[0133] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the application, the features and functions of two or more modules or units described above can be concretized in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be concretized.

[0134] In an embodiment of the present application, a computer-readable storage medium is further provided, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned wire control braking method is implemented.

[0135] It should be noted that the computer-readable storage medium shown in this application can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination thereof. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, device or device. The program code contained on the computer-readable storage medium can be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, radio frequency, etc., or any suitable combination thereof.

[0136] In an embodiment of the present application, a computer program product is further provided. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned wire control braking method.

[0137] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0138] The foregoing description is intended only to provide specific embodiments of the present application, which will enable those skilled in the art to understand and implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments described herein, but is intended to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A fully decoupled wire control brake method, characterized in that: Applied to a brake-by-wire system, the brake-by-wire system, the method comprising: Check whether the brake-by-wire system is powered on normally; If the wire control brake system is not powered on normally, the system enters the mechanical backup brake mode; If the brake-by-wire system is powered on normally, detecting whether the brake-by-wire system has a fault; If there is a fault in the brake-by-wire system, a mechanical backup braking mode is entered; If there is no fault in the brake-by-wire system, detecting whether the brake-by-wire system is in a pedal-powered state; If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered; If the brake-by-wire system is in a pedal-powered state, determining whether the stroke of the mechanical push rod at the moment of power-on is greater than a first stroke value; If the stroke of the mechanical push rod is less than or equal to the first stroke value, entering the normal wire control brake mode; If the stroke of the mechanical push rod is greater than the first stroke value, entering the pedal-powered braking mode; In the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is applied, and a first target brake pressure is determined according to the stroke of the mechanical push rod; a second target brake pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target brake pressure and the second target brake pressure is selected as the target brake pressure, and the target brake pressure is output; detecting whether the brake-by-wire system is powered off; If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault; If it is detected that the brake-by-wire system is powered off, the process ends.

2. The method according to claim 1, characterized in that The method further comprises: When the wire control brake system is in the pedal-operated electric braking mode, the stroke of the mechanical push rod is detected. If the stroke of the mechanical push rod is less than a second stroke value, the normal wire control brake mode is entered, wherein the second stroke value is less than the first stroke value.

3. The method according to claim 1, characterized in that Before detecting whether the brake-by-wire system is in a pedal-powered state, the method further includes: If the vehicle is equipped with an electronic parking brake system, check whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched since power was applied; If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched, then executing the step of detecting whether the brake-by-wire system is in the pedal-on state; If the electronic parking brake system is in the applied state and its state has not been switched before, it enters the mechanical backup brake mode.

4. The method according to claim 1, wherein The method further comprises: If slippage is detected in the pedal-operated power-on braking mode, the target brake pressure is increased according to a set increase gradient control based on the slippage state, wherein the increased target brake pressure is not greater than the maximum allowable operating pressure of the brake-by-wire system; After detecting that the vehicle has stopped slipping, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is stationary before slipping, the increased brake pressure will be reduced to the maximum brake pressure limit value according to the set descent gradient, and when the stroke of the mechanical push rod is less than the second stroke value, the normal wire control braking mode will be entered.

5. The method according to any one of claims 1 to 4, characterized in that The detecting whether the brake-by-wire system is in a pedal-powered state includes: If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state; When the brake-by-wire system is in a pedal-on state, the brake-by-wire system exits the pedal-on state only after detecting that the brake pedal is fully released. If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

6. The method according to any one of claims 1 to 4, characterized in that After entering the mechanical backup braking mode, the method further includes: Control the manual cylinder circuit isolation valve to remain in the open state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain in the closed state, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side brake circuit. When the brake pedal is stepped on to build up pressure, the connected brake circuit pressure is built up normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

7. The method according to any one of claims 1 to 4, characterized in that After entering the normal brake-by-wire mode, the method further includes: The manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state. The pressure in the manual cylinder and the simulation cylinder is measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side are measured by the servo cylinder pressure sensor.

8. A fully decoupled brake-by-wire system, characterized in that: include: Controller, brake pedal, mechanical push rod, travel sensor, fluid reservoir, manual cylinder including piston and spring, manual cylinder pressure sensor, manual cylinder circuit isolation valve, simulation cylinder circuit isolation valve, simulation cylinder, servo cylinder circuit isolation valve, servo cylinder pressure sensor, servo cylinder body, servo cylinder piston, ball screw transmission mechanism and servo motor; The controller is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system is faulty; If the brake-by-wire system has a fault, the system enters a mechanical backup braking mode; if the brake-by-wire system does not have a fault, the system detects whether the brake-by-wire system is in a pedal-powered state; as well as, If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered; if the brake-by-wire system is in the pedal-powered state, whether the stroke of the mechanical push rod at the moment of power-on is greater than a first stroke value is determined; If the stroke of the mechanical push rod is less than or equal to the first stroke value, the normal wire control braking mode is entered; if the stroke of the mechanical push rod is greater than the first stroke value, the pedal-powered braking mode is entered; in the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after being energized, and the first target braking pressure is determined according to the stroke of the mechanical push rod; the second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the target braking pressure is output; it is detected whether the wire control braking system is powered off; if it is detected that the wire control braking system is not powered off, the step of detecting whether the wire control braking system is faulty is returned to; if it is detected that the wire control braking system is powered off, the process ends.

9. The system according to claim 8, characterized in that The controller is further configured to detect the stroke of the mechanical push rod when the brake-by-wire system is in the pedal-operated electric braking mode, and enter a normal brake-by-wire mode if the stroke of the mechanical push rod is less than a second stroke value, wherein the second stroke value is less than the first stroke value.

10. The system according to claim 8, wherein: The controller is further configured to, before detecting whether the brake-by-wire system is in the pedal-powered state, if the vehicle is equipped with an electronic parking brake system, detect whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched after power-on; if the electronic parking brake system is in the unengaged state, or the electronic parking brake system is in the engaged state and its state has ever been switched after power-on, execute the step of detecting whether the brake-by-wire system is in the pedal-powered state; if the electronic parking brake system is in the engaged state and its state has ever been switched after power-on; enter the mechanical backup braking mode.

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