A brake-by-wire smooth transition control method and system

Abstract

The application provides a kind of brake-by-wire smooth transition control method and system.A kind of brake-by-wire smooth transition control method, the method comprises the following steps: brake system state information is judged based on the working mode of brake system;When system is not normally powered on or there is a fault, select mechanical backup mode;When system is normally powered on, there is no fault and is not in pedal down power-on state, select normal brake-by-wire mode;When system is normally powered on, there is no fault and is in pedal down power-on state, select brake system working mode based on the comparison result of human cylinder pressure and first preset pressure threshold;Wherein, when human cylinder pressure is greater than first preset pressure threshold, select special power-on mode, when human cylinder pressure is not greater than first preset pressure threshold, select normal brake-by-wire mode;The valve group state in hydraulic circuit is controlled to realize brake system smooth transition control.The application improves driving experience and improves safety.

Description

Technical Field

[0001] The present invention relates to a brake-by-wire control method and system, and in particular to a brake-by-wire smooth transition control method and system, belonging to the technical field of brake-by-wire. Background Art

[0002] With the advancement of automotive electronics, brake-by-wire systems have become an essential feature of modern vehicles. Fully decoupled brake-by-wire systems completely separate pedal input from the execution circuit, enabling more flexible braking control and providing essential underlying support for advanced driver assistance systems and autonomous driving technologies. However, during system mode switching (especially in scenarios like power-on and fault switching), brake fluid pressure imbalance can cause the pedal to suddenly sink when the pedal is pressed, severely impacting the driver experience. Braking force is discontinuous when switching between different braking modes, potentially leading to sudden changes in braking effectiveness. Increased system parameter uncertainty during mode switching makes it difficult to ensure control accuracy. Furthermore, safety issues arise during the coordinated operation of the electronic parking and service brake systems. These issues not only impact driving comfort but can also pose safety risks in specific scenarios, such as hill starts. Summary of the Invention

[0003] Based on the above background, the object of the present invention is to provide a brake-by-wire smooth transition control method to achieve smooth transition between various modes of a fully decoupled brake-by-wire system, thereby improving driving experience and enhancing safety.

[0004] Another object of the present invention is to provide a brake-by-wire smooth transition control system.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A brake-by-wire smooth transition control method, the method comprising the following steps:

[0007] Acquiring brake system status information, wherein the brake system status information includes system power status, system fault status, brake pedal operation status, and manual cylinder pressure status;

[0008] Based on the brake system status information, determining a brake system operating mode, wherein the brake system operating mode includes a normal wire control mode, a special power-on mode, and a mechanical backup mode;

[0009] When the system is not powered on normally or there is a fault, the mechanical backup mode is selected;

[0010] When the system is powered on normally, there is no fault and it is not in the pedal-down power-on state, the normal wire control mode is selected;

[0011] When the system is normally powered on, no fault exists, and is in the pedal depression power-on state, the brake system working mode is selected based on the comparison result of the human power cylinder pressure and the first preset pressure threshold value; wherein when the human power cylinder pressure is greater than the first preset pressure threshold value, the special power-on mode is selected, and when the human power cylinder pressure is not greater than the first preset pressure threshold value, the normal drive-by-wire mode is selected;

[0012] Based on the selected brake system working mode, the valve group state in the hydraulic circuit is controlled to realize smooth transition control of the brake system.

[0013] As a preferred, the control step in the normal drive-by-wire mode includes:

[0014] The isolation valve corresponding to the human power cylinder hydraulic circuit is controlled to change to a closed state;

[0015] The isolation valves corresponding to the analog cylinder hydraulic circuit and the servo cylinder hydraulic circuit are controlled to change to an open state;

[0016] The mapping relationship between the brake pedal stroke and the target brake pressure is established;

[0017] The servo actuator is controlled to output a brake force corresponding to the target brake pressure.

[0018] As a preferred, the control step in the special power-on mode includes:

[0019] The isolation valve corresponding to the analog cylinder hydraulic circuit is maintained in a closed state;

[0020] The isolation valve corresponding to the human power cylinder hydraulic circuit is controlled to change to a closed state;

[0021] A double-source target pressure value is generated, which includes a first target pressure value generated based on brake pedal stroke information, and a second target pressure value generated based on human power cylinder pressure information;

[0022] The larger one of the first target pressure value and the second target pressure value is selected as the final target brake pressure;

[0023] The servo actuator is controlled to output a brake force corresponding to the final target brake pressure.

[0024] As a preferred, the control step in the mechanical backup mode includes:

[0025] The isolation valve corresponding to the human power cylinder hydraulic circuit is maintained in an open state;

[0026] The isolation valves corresponding to the analog cylinder hydraulic circuit and the servo cylinder hydraulic circuit are maintained in a closed state;

[0027] The human power cylinder is directly communicated with the wheel cylinder hydraulic circuit.

[0028] As preferred, the brake-by-wire smooth transition control method further comprises the following steps:

[0029] In the special power-up mode, the human cylinder pressure change is monitored;

[0030] When the human cylinder pressure is reduced to below the second preset pressure threshold, the brake system is switched from the special power-up mode to the normal brake-by-wire mode;

[0031] Wherein, the second preset pressure threshold is less than the first preset pressure threshold.

[0032] As preferred, the brake-by-wire smooth transition control method further comprises the following steps:

[0033] The validity of multiple pressure sensor signals including the human cylinder pressure sensor and the electronic stability control system pressure sensor is detected;

[0034] When the human cylinder pressure sensor signal is invalid, the system enters the mechanical backup mode;

[0035] When the electronic stability control system pressure sensor signal is invalid, its measurement value is set to zero;

[0036] When both pressure sensor signals are valid, the measurement values of the two pressure sensors are compared and analyzed;

[0037] When the measurement value difference of the two pressure sensors exceeds the preset difference threshold, and the measurement value of the human cylinder pressure sensor is less than that of the electronic stability control system pressure sensor, the system enters the mechanical backup mode.

[0038] As preferred, the brake-by-wire smooth transition control method further comprises the following steps:

[0039] The state of the electronic parking brake system and its state change history are monitored;

[0040] When the electronic parking brake system is in the pull-up state and the state has not been switched after power-up, the system enters the mechanical backup mode;

[0041] When the electronic parking brake system is in the release state or the state has been switched, the system operating mode is determined according to other state information.

[0042] As preferred, the brake-by-wire smooth transition control method further comprises the following steps:

[0043] In the special power-up mode, the vehicle motion state parameters are monitored in real time;

[0044] When the vehicle is detected to have a tendency to roll, the target brake pressure is gradually increased according to a preset increment;

[0045] When the rolling state is eliminated, if the increased target brake pressure exceeds the maximum pressure limit value before the rolling state, the target brake pressure is gradually reduced according to the preset decrement to within the limit value;

[0046] When the pressure of the manual cylinder meets the conditions, it smoothly transitions from the special power-on mode to the normal wire control mode.

[0047] A brake-by-wire smooth transition control system comprising:

[0048] A state monitoring module is used to obtain brake system state information, including system power supply state, system fault state, brake pedal operation state and manual cylinder pressure state;

[0049] a mode determination module, configured to determine a braking system operating mode based on the braking system state information, wherein the braking system operating modes include a normal drive-by-wire mode, a special power-on mode, and a mechanical backup mode;

[0050] A transition control module is used to control the valve group state in the hydraulic circuit based on the selected braking system operating mode to achieve smooth transition control between different braking system modes;

[0051] A target pressure generation module is used to generate a final target brake pressure based on brake pedal travel information and manual cylinder pressure information in a special power-on mode;

[0052] The roll-off protection module is used to monitor the vehicle's motion status in a special power-on mode and dynamically adjust the target brake pressure when a roll-off trend is detected.

[0053] Preferably, the brake-by-wire smooth transition control system further comprises:

[0054] A hydraulic adjustment module, comprising a manual cylinder, a simulation cylinder, a servo cylinder and corresponding isolation valve groups;

[0055] A sensor module, the sensor module including a travel sensor for detecting a brake pedal travel and a pressure sensor for detecting a manual cylinder pressure;

[0056] An execution control module includes a servo motor and a transmission system thereof for driving a servo cylinder.

[0057] Compared with the prior art, the present invention has the following advantages:

[0058] The present invention provides a brake-by-wire smooth transition control method and system, which achieves a smooth and seamless transition between different braking modes while ensuring braking safety, effectively solving the pedal sinking problem when the pedal is pressed to power on, while taking into account the safety requirements of special scenarios, thereby improving the performance and user experience of the fully decoupled brake-by-wire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention 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, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0060] Figure 1 is a schematic structural diagram of a fully decoupled brake-by-wire system according to an embodiment of the present invention;

[0061] Figure 2 1 is a flow chart of a brake-by-wire smooth transition control method according to the present invention;

[0062] In the figure: 1. Brake pedal; 2. Mechanical push rod; 3. Travel sensor; 4. Fluid storage tank; 5. Manual cylinder; 6. Manual cylinder pressure sensor; 7. Manual cylinder circuit isolation valve; 8. Simulation cylinder circuit isolation valve; 9. Simulation cylinder; 10. Servo cylinder circuit isolation valve; 11. Servo cylinder pressure sensor; 12. Servo cylinder body; 13. Servo cylinder piston; 14. Ball screw transmission mechanism; 15. Servo motor. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0064] In the present invention, unless otherwise specified, all parts and percentages are by weight. The equipment and raw materials used are commercially available or commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are all universal standard parts or components known to those skilled in the art. Their structures and principles are known to those skilled in the art through technical manuals or routine experimental methods.

[0065] The following detailed description of the embodiments of the present invention is made in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be implemented by those skilled in the art without these specific details.

[0066] The embodiment of the present invention discloses a brake-by-wire smooth transition control method, which is applied to Figure 1 The fully decoupled brake-by-wire system shown in the figure includes a brake pedal 1, a mechanical push rod 2, a travel sensor 3, a fluid reservoir 4, a manual cylinder 5 (including a first piston, a second piston, and corresponding springs), a manual cylinder pressure sensor 6, a manual cylinder circuit isolation valve 7, a simulation cylinder circuit isolation valve 8, a simulation cylinder 9, a servo cylinder circuit isolation valve 10, a servo cylinder pressure sensor 11, a servo cylinder body 12, a servo cylinder piston 13, a ball screw transmission mechanism 14, and a servo motor 15. The manual cylinder circuit isolation valve 7 is a normally open valve, while the simulation cylinder circuit isolation valve 8 and the servo cylinder circuit isolation valve 10 are both normally closed valves.

[0067] The brake-by-wire smooth transition control method comprises the following steps:

[0068] Obtaining brake system status information, including system power status, system fault status, brake pedal operation status, and manual cylinder pressure status;

[0069] Based on the brake system status information, determine the brake system working mode, which includes normal wire control mode, special power-on mode and mechanical backup mode;

[0070] When the system is not powered on normally or there is a fault, select the mechanical backup mode;

[0071] When the system is powered on normally, there is no fault and the system is not in the pedal-down power-on state, select the normal wire control mode;

[0072] When the system is powered on normally, has no faults, and is in the pedal-pressed power-on state, a braking system operating mode is selected based on a comparison result of the manual cylinder pressure and a first preset pressure threshold; wherein, when the manual cylinder pressure is greater than the first preset pressure threshold, the special power-on mode is selected, and when the manual cylinder pressure is not greater than the first preset pressure threshold, the normal wire control mode is selected;

[0073] Based on the selected braking system operating mode, the valve group state in the hydraulic circuit is controlled to achieve smooth transition control of the braking system.

[0074] like Figure 2 As shown, the brake-by-wire smooth transition control method specifically includes the following steps.

[0075] Step S100: Detect whether the brake-by-wire system is powered on normally.

[0076] If the brake-by-wire system is not powered on normally, step S110 is executed; if the brake-by-wire system is powered on normally, step S120 is executed.

[0077] Step S110: Entering the mechanical backup braking mode.

[0078] In the mechanical backup braking mode, the manual cylinder circuit isolation valve 7 is controlled to remain in the open state, and the simulation cylinder circuit isolation valve 8 and the servo cylinder circuit isolation valve 10 are controlled to remain in the closed state. At this time, the brake pedal 1 is pressed, and at the same time, the mechanical push rod 2 is pushed to the left, the piston in the manual cylinder 5 moves to the left, and the brake fluid in the two piston chambers of the manual cylinder is sealed and compressed. Since the manual cylinder circuit isolation valve 7 is in the open state, the two piston chambers of the manual cylinder 5 are connected to the electronic stability control system (ESC) and the wheel side brake circuit. When the brake pedal 1 is pressed to build pressure, the pressure of the connected brake circuit is built up normally, and the pressure is greater than 0, while the circuit pressure from the simulation cylinder circuit isolation valve 8 to the simulation cylinder 9 is 0, and the pressure before the servo cylinder circuit isolation valve 10 and in the servo cylinder is also 0.

[0079] Step S120: Detect whether there is any fault in the brake-by-wire system.

[0080] In this embodiment, whether the brake-by-wire system has a fault is determined by detecting whether the servo motor 15, the manual cylinder circuit isolation valve 7, and the servo cylinder circuit isolation valve 10 are faulty. If none of the servo motor 15, the manual cylinder circuit isolation valve 7, and the servo cylinder circuit isolation valve 10 are faulty, the brake-by-wire system is determined to have no fault. If at least one of the servo motor 15, the manual cylinder circuit isolation valve 7, and the servo cylinder circuit isolation valve 10 is faulty, the brake-by-wire system is determined to have a fault.

[0081] If there is a fault in the brake-by-wire system, step S110 is executed; if there is no fault in the brake-by-wire system, step S130 is executed.

[0082] Step S130: Detect whether the brake-by-wire system is in a pedal-powered state.

[0083] The "pedal-on" state refers to the state in which the brake pedal 1 is detected as being depressed at the moment of power-on. This means that the controller recognizes that the brake pedal 1 is depressed at the moment of power-on. As long as the brake-by-wire system is identified as in the "pedal-on" state at the moment of power-on, and the exit conditions are not met, the system remains in the "pedal-on" state. While the brake-by-wire system is in the "pedal-on" state, it exits the "pedal-on" state only when it detects that the brake pedal has been fully released.

[0084] If the brake-by-wire system is not in the pedal-on-power state, step S140 is executed; if the brake-by-wire system is in the pedal-on-power state, step S150 is executed.

[0085] Step S140: Enter normal brake-by-wire mode.

[0086] After entering the normal brake-by-wire mode, all solenoid valves are energized, i.e., the control manual cylinder circuit isolation valve 7 is switched from the open state to the closed state, and the control analog cylinder circuit isolation valve 8 and the servo cylinder circuit isolation valve 10 are switched from the closed state to the open state. The pressure in the manual cylinder 5 and the analog cylinder 9 can be measured by the manual cylinder pressure sensor 6, and the pressure in the servo cylinder body 12, the hydraulic circuit before and after the servo cylinder circuit isolation valve 10, the electronic stability control system, and the wheel can be measured by the servo cylinder pressure sensor 11.

[0087] Step S150: Determine whether the pressure in the manual cylinder at the power-on moment is greater than a first pressure threshold.

[0088] The pressure in the manual cylinder at the power-on moment of the brake pedal is related to the change in pedal force, the change in mechanical push rod stroke, the change in manual cylinder pressure, and the change in mechanical push rod stroke. The greater the pressure in the manual cylinder when the brake pedal is powered on, the more obvious the pedal sinking. In this embodiment, the first pressure threshold is set to P1. When the pressure in the manual cylinder is greater than P1, the analog cylinder balance will cause a significant pedal sinking feeling, and special measures need to be taken.

[0089] If the pressure in the manual cylinder is less than or equal to the first pressure threshold, step S140 is executed; if the pressure in the manual cylinder is greater than the first pressure threshold, step S160 is executed.

[0090] Step S160: Enter pedal-on-power braking mode.

[0091] In the pedal-on-power braking mode, the control analog cylinder circuit isolation valve 8 remains in the closed state, and the control manual cylinder circuit isolation valve 7 is energized and switched from the open state to the closed state. In this way, the brake fluid in the manual cylinder 5 after the analog cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 7 is cut off, thereby avoiding sudden pedal sinking when the brake pedal is deeply pressed and powered on.

[0092] Step S170: Determine the target brake pressure and control the brake output.

[0093] In the pedal-on-power braking mode, the following operations are performed:

[0094] Determine the first target brake pressure according to the stroke of the mechanical push rod 2;

[0095] Determine the second target brake pressure according to the pressure detected by the manual cylinder pressure sensor 6;

[0096] The greater one of the first target brake pressure and the second target brake pressure is selected as the target brake pressure.

[0097] Based on the target brake pressure, the servo motor 15 is controlled to output a corresponding brake force.

[0098] Although the manual cylinder circuit isolation valve 7 and the simulation cylinder circuit isolation valve 8 are closed, the brake pedal 1 cannot be stepped on any more, but if the driver continues to increase the force of stepping on the brake pedal 1, the measured value of the manual cylinder pressure sensor 6 will be further increased, and the target pressure of the brake system is increased based on the increase of the value, so that a greater brake pressure is generated at the wheel, and the brake demand is met.

[0099] Step S180: In the step-on power braking mode, the pressure in the manual cylinder is detected, and if the pressure in the manual cylinder is less than a second pressure threshold, the normal brake-by-wire mode is entered, wherein the first pressure threshold is greater than the second pressure threshold.

[0100] In this embodiment, the second pressure threshold P2 is set to be less than the first pressure threshold P1. This design avoids frequent mode switching of the system near the threshold by introducing hysteresis. When the driver slightly releases the brake pedal 1 to reduce the pressure in the manual cylinder to below P2, the system switches from the step-on power braking mode to the normal brake-by-wire mode.

[0101] Step S190: In the step-on power braking mode, it is detected whether the vehicle is rolling.

[0102] In this embodiment, the speed, acceleration and slope information of the vehicle are monitored to determine whether the vehicle is rolling. If it is detected that the vehicle is rolling, the system will increase the target brake pressure according to the set increase gradient according to the rolling state, wherein the increased target brake pressure is not greater than the maximum allowable working pressure of the brake-by-wire system.

[0103] After detecting that the rolling stops, if the increased target brake pressure is greater than the maximum brake pressure limit value of the vehicle in the stationary state before rolling, the increased target brake pressure is decreased to the maximum brake pressure limit value according to the set decrease gradient, and the normal brake-by-wire mode is entered when the pressure in the manual cylinder is less than the second pressure threshold.

[0104] Step S200: It is detected whether the brake-by-wire system is powered off.

[0105] If it is detected that the brake-by-wire system is not powered off, the process returns to step S120; if it is detected that the brake-by-wire system is powered off, the process ends.

[0106] This embodiment further provides a signal verification mechanism in the pedal-powered state. Before determining whether the pressure in the manual cylinder is greater than the first pressure threshold at the moment of power-on, the method further includes the following steps:

[0107] If the brake-by-wire system is in the pedal-powered state, a signal check is performed on the pressure sensor of the electronic stability control system itself to determine whether the first pressure measurement value is valid; a signal check is performed on the manual cylinder pressure sensor to determine whether the second pressure measurement value is valid.

[0108] If the first pressure measurement value is invalid, the first pressure measurement value is set to 0; if the second pressure measurement value is invalid, the mechanical backup braking mode is entered.

[0109] If both the first pressure measurement value and the second pressure measurement value are valid, determining whether there is an abnormality in the pressure within the brake-by-wire system by comparing the first pressure measurement value and the second pressure measurement value:

[0110] If the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to the pressure difference threshold, determining that there is no abnormality in the pressure within the brake-by-wire system;

[0111] If a difference between the first pressure measurement value and the second pressure measurement value is greater than a pressure difference threshold, determining that there is an abnormality in the pressure within the brake-by-wire system;

[0112] If the difference between the second pressure measurement and the first pressure measurement is greater than the pressure difference threshold, it is determined that there is no abnormality in the pressure within the brake-by-wire system.

[0113] If there is no abnormality in the pressure within the wire control brake system, the step of determining whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold is executed; if there is an abnormality in the pressure within the wire control brake system, the mechanical backup braking mode is entered.

[0114] This embodiment further provides a control strategy that takes into account the state of the electronic parking brake system. Before detecting whether the brake-by-wire system is in the pedal-on state, the method further includes the following steps:

[0115] In the case that the vehicle is equipped with an electronic parking brake system, it is detected whether the electronic parking brake system is in a pulled-up state and whether the state of the electronic parking brake system has never been switched after power-on.

[0116] 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, a step of detecting whether the brake-by-wire system is in the pedal-on state is performed.

[0117] 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.

[0118] For vehicles equipped with an electronic parking brake system, if the system is in the applied state and has not previously switched to another state when the brake pedal is pressed, the mechanical backup brake mode logic can be maintained. This prevents sudden pedal depression and possible vehicle rollaway due to insufficient brake pressure.

[0119] This method selects a mode based on the manual cylinder pressure threshold, fully leveraging the characteristics of the hydraulic system. When the manual cylinder pressure exceeds the first pressure threshold, the hydraulic flow path between the manual cylinder and the simulated cylinder is effectively blocked by maintaining the closed isolation valve in the simulated cylinder circuit and closing the manual cylinder circuit isolation valve, fundamentally avoiding the pedal sinking phenomenon during the hydraulic balancing process. Secondly, by introducing a dual-target pressure generation mechanism (based on the mechanical push rod stroke and manual cylinder pressure) and adopting a maximum value strategy, sufficient braking force is ensured in all circumstances to ensure driving safety. In addition, different pressure thresholds are designed for mode entry and exit judgment (the first pressure threshold is greater than the second pressure threshold), cleverly utilizing hysteresis characteristics to prevent the system from frequently switching modes near the thresholds.

[0120] The following significant effects are achieved through the method provided by the present invention. The pedal sinking phenomenon when the pedal is pressed to power on is effectively eliminated, making the brake pedal operation feel more natural and coherent, greatly improving the driver's experience. For special working conditions such as starting on a slope, through the slip detection and anti-slip control strategy, the system can intelligently increase the brake pressure to deal with the risk of slipping, and steadily reduce the pressure after the risk is eliminated, ensuring safety while maintaining a good driving experience. Through measures such as multiple sensor signal verification, abnormality judgment mechanism, and electronic parking brake system status inspection, the system can respond to various abnormal situations and switch to a safe backup mode in time, effectively preventing braking risks caused by sensor abnormalities, system failures, etc.

[0121] An embodiment of the present invention further discloses a brake-by-wire smooth transition control system, comprising:

[0122] The status monitoring module is used to obtain the brake system status information, including the system power status, system fault status, brake pedal operation status and manual cylinder pressure status;

[0123] A mode determination module is used to determine the operating mode of the brake system based on the brake system status information. The brake system operating modes include normal wire control mode, special power-on mode, and mechanical backup mode.

[0124] A transition control module is used to control the valve group state in the hydraulic circuit based on the selected braking system operating mode to achieve smooth transition control between different braking system modes;

[0125] A target pressure generation module is used to generate a final target brake pressure based on brake pedal travel information and manual cylinder pressure information in a special power-on mode;

[0126] The roll-off protection module is used to monitor the vehicle's motion status and dynamically adjust the target brake pressure when a roll-off trend is detected in a special power-on mode;

[0127] Hydraulic adjustment module, which includes a manual cylinder, a simulation cylinder, a servo cylinder and corresponding isolation valve groups;

[0128] A sensor module includes a travel sensor for detecting the travel of the brake pedal and a pressure sensor for detecting the pressure of the manual cylinder;

[0129] The execution control module includes a servo motor and a transmission system for driving the servo cylinder.

[0130] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A brake-by-wire smooth transition control method, characterized by: The method comprises the following steps: Acquiring brake system status information, wherein the brake system status information includes system power status, system fault status, brake pedal operation status, and manual cylinder pressure status; Based on the brake system status information, determining a brake system operating mode, wherein the brake system operating mode includes a normal wire control mode, a special power-on mode, and a mechanical backup mode; When the system is not powered on normally or there is a fault, the mechanical backup mode is selected; When the system is powered on normally, there is no fault and it is not in the pedal-down power-on state, the normal wire control mode is selected; When the system is powered on normally, has no faults, and is in the pedal-pressed power-on state, a braking system operating mode is selected based on a comparison result of the manual cylinder pressure and a first preset pressure threshold; wherein, when the manual cylinder pressure is greater than the first preset pressure threshold, the special power-on mode is selected, and when the manual cylinder pressure is not greater than the first preset pressure threshold, the normal drive-by-wire mode is selected; Based on the selected brake system operating mode, control the valve group state in the hydraulic circuit to achieve smooth transition control of the brake system; The control steps in the normal wire control mode include: Control the isolation valve corresponding to the hydraulic circuit of the manual cylinder to change to a closed state; Control the isolation valves corresponding to the hydraulic circuit of the simulation cylinder and the hydraulic circuit of the servo cylinder to be changed to an open state; Establishing a mapping relationship between brake pedal travel and target brake pressure; controlling the servo actuator to output a braking force corresponding to the target braking pressure; The control steps in the special power-on mode include: Keep the isolation valve corresponding to the hydraulic circuit of the simulated cylinder in the closed state; Control the isolation valve corresponding to the hydraulic circuit of the manual cylinder to change to a closed state; generating a dual-source target pressure value, the dual-source target pressure value comprising a first target pressure value generated based on brake pedal stroke information and a second target pressure value generated based on manual cylinder pressure information; selecting the larger of the first target pressure value and the second target pressure value as the final target brake pressure; controlling the servo actuator to output a braking force corresponding to the final target braking pressure; The control steps in the mechanical backup mode include: Keep the isolation valve corresponding to the hydraulic circuit of the manual cylinder open; Keep the isolation valves corresponding to the simulation cylinder hydraulic circuit and the servo cylinder hydraulic circuit closed; Make the manual cylinder and the wheel cylinder hydraulic circuit directly connected; The brake-by-wire smooth transition control method further comprises the following steps: In the special power-on mode, monitoring the pressure change of the manual cylinder; When the pressure of the manual cylinder drops below a second preset pressure threshold, the braking system is switched from the special power-on mode to the normal wire control mode; Wherein, the second preset pressure threshold is less than the first preset pressure threshold; The brake-by-wire smooth transition control method further comprises the following steps: Perform validity checks on multiple pressure sensor signals, including the human cylinder pressure sensor and the electronic stability control system pressure sensor; When the signal from the manual cylinder pressure sensor is invalid, the system enters the mechanical backup mode; When the ESC pressure sensor signal is invalid, its measurement value is set to zero; When the signals of the two pressure sensors are both valid, the measured values ​​of the two pressure sensors are compared and analyzed; When the difference between the measured values ​​of the two pressure sensors exceeds a preset difference threshold, and the measured value of the manual cylinder pressure sensor is less than the measured value of the electronic stability control system pressure sensor, the system enters the mechanical backup mode; The brake-by-wire smooth transition control method further comprises the following steps: Monitor the status of the electronic parking brake system and its status change history; When the electronic parking brake system is in the applied state and has not switched to the same state since power-on, the system enters the mechanical backup mode; When the electronic parking brake system is in the released state or has been switched, the system operating mode is determined based on other state information; The brake-by-wire smooth transition control method further comprises the following steps: In special power-on mode, real-time monitoring of vehicle motion parameters; When the vehicle is detected to be sliding, the target brake pressure is gradually increased according to the preset increments; When the rolling state is eliminated, if the increased target brake pressure exceeds the maximum pressure limit value before the rolling state, the target brake pressure is gradually reduced according to the preset decrement to within the limit value; When the pressure of the manual cylinder meets the conditions, it smoothly transitions from the special power-on mode to the normal wire control mode.

2. A brake-by-wire smooth transition control system using the brake-by-wire smooth transition control method according to claim 1, characterized in that: The system includes: A state monitoring module is used to obtain brake system state information, including system power supply state, system fault state, brake pedal operation state and manual cylinder pressure state; a mode determination module, configured to determine a braking system operating mode based on the braking system state information, wherein the braking system operating modes include a normal drive-by-wire mode, a special power-on mode, and a mechanical backup mode; A transition control module is used to control the valve group state in the hydraulic circuit based on the selected braking system operating mode to achieve smooth transition control between different braking system modes; A target pressure generation module is used to generate a final target brake pressure based on brake pedal travel information and manual cylinder pressure information in a special power-on mode; The roll-off protection module is used to monitor the vehicle's motion status in a special power-on mode and dynamically adjust the target brake pressure when a roll-off trend is detected.

3. The brake-by-wire smooth transition control system according to claim 2, characterized in that: The system also includes: A hydraulic adjustment module, comprising a manual cylinder, a simulation cylinder, a servo cylinder and corresponding isolation valve groups; A sensor module, the sensor module including a travel sensor for detecting a brake pedal travel and a pressure sensor for detecting a manual cylinder pressure; An execution control module includes a servo motor and a transmission system thereof for driving a servo cylinder.

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