Method for controlling an electro-hydraulic brake

Abstract

According to at least one embodiment, this disclosure provides a control method for an electro-hydraulic brake, which includes an auxiliary braking system that generates braking force in a vehicle when a main braking system fails. The control method includes: determining whether the main braking system has failed; when the main braking system has failed, opening a rear wheel high-pressure switching valve (HSV) connecting the rear wheel of the main braking system and the low-pressure accumulator (LPA) of the auxiliary braking system; determining whether the driver has intervened in braking; and controlling the auxiliary braking system to generate braking force in the vehicle. According to this disclosure, the control method for the electro-hydraulic brake has the effect of reducing manufacturing costs and increasing assembly convenience by controlling the auxiliary braking system, which can perform 2-channel pressurization control and 1-channel depressurization control.

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2021-0152022, filed on November 8, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a control method for an electro-hydraulic brake. Background Technology

[0004] The description in this section provides only background information for this disclosure and does not include any configuration related technologies.

[0005] An autonomous vehicle that, in the event of a failure in the main braking system, uses an auxiliary braking system positioned between the main braking system and multiple wheel braking devices to ensure redundancy.

[0006] The auxiliary braking system of the related technology performs 2-channel pressurization / depressurization control and 2-channel depressurization control. It performs the functions of pressurizing / depressurizing the front wheels and depressurizing the rear wheels. For this purpose, four input lines and four output lines, a total of eight lines, should be connected to the auxiliary braking system. Therefore, there are problems of increased manufacturing costs and assembly complexity for the braking system.

[0007] When a driver intervenes in braking while using redundancy, the vehicle's brakes may disengage due to difficulty in adjusting the pedal stroke. As a result, braking force may not be properly transmitted to the vehicle, potentially leading to an accident. Summary of the Invention

[0008] According to at least one embodiment, this disclosure provides a control method for an electro-hydraulic brake, the electro-hydraulic brake including an auxiliary braking system that generates braking force in a vehicle when a main braking system fails. The control method includes: determining whether the main braking system has failed; when the main braking system has failed, opening a high-pressure switching valve (HSV) connecting the rear wheel of the main braking system and the low-pressure accumulator (LPA) of the auxiliary braking system; determining whether the driver has intervened in braking; and controlling the auxiliary braking system to generate braking force in the vehicle. Attached Figure Description

[0009] Figure 1 This is a hydraulic circuit diagram of an electro-hydraulic brake according to an embodiment of the present disclosure.

[0010] Figure 2 This is a flowchart of a method for controlling an auxiliary braking system of an electro-hydraulic brake according to an embodiment of the present disclosure.

[0011] Figure 3 This is a flowchart of a method for controlling an auxiliary braking system of an electro-hydraulic brake according to another embodiment of the present disclosure. Detailed Implementation

[0012] The control method for an electro-hydraulic brake according to the embodiment can generate braking force in a vehicle by controlling an auxiliary braking system that can perform 2-channel pressurization / depressurization control and 1-channel depressurization control.

[0013] According to one embodiment, the control method for an electro-hydraulic brake can use a front wheel-auxiliary braking system and a rear wheel electric parking brake in a redundant situation when the driver interferes with braking.

[0014] The purpose of this disclosure is not limited to the above-described purposes, and other purposes will be clearly understood by those skilled in the art from the following description.

[0015] In the following description, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description below, similar reference numerals preferably denote similar elements, even though these elements are shown in different drawings. Furthermore, in the following description of some embodiments, for the purpose of clarity and brevity, detailed descriptions of relevant known components and functions will be omitted where they are considered to obscure the subject matter of the present disclosure.

[0016] Furthermore, alphanumeric codes, such as first, second, i), ii), a), b), etc., in component numbering are used only for the purpose of distinguishing one component from another, and do not imply or suggest the substance, order, or sequence of the components. Throughout the specification, when a component is described as "comprising" or "containing," that component means that it further includes other components, without excluding their presence, unless specifically described to the contrary. Terms such as "unit" or "module" refer to one or more units for performing at least one function or operation, which may be implemented by hardware, software, or a combination thereof.

[0017] Regarding the terms "forward" or "backward" related to the relative position of the centerline in this disclosure, the portion closer to the reservoir 10 is described as "forward" when brake fluid flows, while the portion farther from the reservoir is described as "backward." However, this does not only mean that the forward or backward lines are directly continuous, but also that the lines are relatively far apart, even if they are spaced apart.

[0018] Figure 1 This is a hydraulic circuit diagram of an electro-hydraulic brake according to an embodiment of the present invention.

[0019] Figure 1 The hydraulic circuit diagram shown is only a conceptual representation of a configuration for ease of description, and the actual positions of the hydraulic blocks and the lines formed within them may differ. Figure 1 In the diagram, inlet pipelines are represented by thick lines, outlet pipelines by medium lines, and circulation pipelines by thin lines.

[0020] refer to Figure 1 The electro-hydraulic brake 1 may include some or all of the following: reservoir 10, brake pedal 11, main braking system 20, and auxiliary braking system 100.

[0021] The reservoir 10 is configured to store brake fluid. The brake pedal 11 can be used by the driver to stroke a piston located in the master cylinder or main brake system 20.

[0022] Multiple wheel brakes FR, FL, and RL can generate braking force at multiple wheels using the pressure of brake fluid discharged from reservoir 10. When the driver depresses brake pedal 11, the control unit can sense the driver's braking request using a Pedal Stroke Sensor (PSS). The control unit that senses the driver's braking request can generate a braking signal. In this case, the braking signal is an electrical signal, which is transmitted to cause braking systems 20 and 100 to generate braking force corresponding to the driver's depressing of brake pedal 11.

[0023] The main braking system 20 is disposed between the reservoir 10 and a plurality of wheel brakes FR, FL, and RL, and can be configured to transmit brake fluid discharged from the reservoir 10 to the plurality of wheel brakes FR, FL, and RL, and control the hydraulic pressure of the brake fluid. When at least some components of the main braking system 20 fail, the control unit can send an auxiliary braking signal to the auxiliary braking system 100. When the auxiliary braking signal is transmitted to the auxiliary braking system 100 by the control unit, all or some components of the auxiliary braking system 100 can be actuated. Therefore, the electro-hydraulic brake according to this disclosure can perform a fault protection function.

[0024] The auxiliary braking system 100 is disposed between the main braking system 20 and the multiple wheel brakes FR, FL, and RL. The auxiliary braking system 100 can be operated when the main braking system 20 fails during automatic driving or when the main braking system 20 fails due to driver intervention.

[0025] The auxiliary braking system 100 may include hydraulic input units 101, 102 and 103, hydraulic output units 104, 105 and 106, inlet lines 111, 112 and 113, actuator 150, traction control valves TCV1 and TCV2, inlet valves FRIV and FLIV, output lines 121, 122 and 123, outlet valves FROV and FLOV, accumulators A1 and A2, oil chambers 131 and 132, circulation lines 141 and 142, and some or all of the high-pressure switching valves HSV1, HSV2 and HSV3.

[0026] One or more hydraulic input units 101, 102, and 103 are provided along the lines through which brake fluid discharged from the main braking system 20 flows into the auxiliary braking system 100. Inlet lines 111, 112, and 113 can be in fluid communication with the main braking system 20 via hydraulic input units 101, 102, and 103.

[0027] One or more hydraulic output units 104, 105, and 106 are provided along the lines through which brake fluid discharged from the main braking system 20 flows to the multiple wheel brakes FR, FL, and RL. Inlet lines 111, 112, and 113 can be in fluid communication with the multiple wheel brakes FR, FL, and RL via hydraulic output units 104, 105, and 106.

[0028] Inlet lines 111, 112 and 113 are formed between hydraulic input units 101, 102 and 103 and hydraulic output units 104, 105 and 106, and can transmit brake fluid discharged from the main braking system 20 to multiple wheel brakes FR, FL and RL.

[0029] The first inlet line 111 is configured to transfer some or all of the brake fluid discharged from the main braking system 20 to the first wheel brake FR. The second inlet line 112 is configured to transfer some or all of the brake fluid discharged from the main braking system 20 to the second wheel brake FL.

[0030] Actuator 150 can increase the pressure of fluid flowing through the first inlet line 111 and the second inlet line 112. Actuator 150 may include some or all of a first pump SP1, a second pump SP2, and an electric motor configured to drive pumps SP1 and SP2. The outlet of the first pump SP1 is connected to a point on the first inlet line 111, and the outlet of the second pump SP2 is connected to a point on the second inlet line 112. When one or more of the first pump SP1 and the second pump SP2 are driven, the internal hydraulic pressure of one or more of the inlet lines 111 and 112, respectively, connected to pumps SP1 and SP2, can be increased.

[0031] The first traction control valve TCV1 is located at a point on the first inlet line 111 and can adjust the opening / closing of the first inlet line 111. The first traction control valve TCV1 can be positioned upstream of the point where the first inlet line 111 and the outlet of the first pump SP1 are connected. The first traction control valve TCV1 can be configured as a normally open type. Therefore, in the non-powered mode where no auxiliary braking signal is applied, the first traction control valve TCV1 is open. When the first traction control valve TCV1 is closed, a portion of the brake fluid pressurized by the first pump SP1 cannot flow back to the main braking system 20.

[0032] The first inlet valve FRIV is located at another point on the first inlet line 111 and can adjust the opening / closing of the first inlet line 111. The first inlet valve FRIV can be located after the point where the first inlet line 111 and the outlet of the first pump SP1 are connected. The first inlet valve FRIV can be configured to be normally open. Therefore, in the non-powered mode where the auxiliary braking signal is not applied, the first inlet valve FRIV is open. When the first inlet valve FRIV is closed, a portion of the brake fluid pressurized by the first pump SP1 is not transmitted to the wheel brakes FR.

[0033] The descriptions of the second inlet line 112, the second traction control valve TCV2, and the second inlet valve FLIV are respectively referred to the descriptions of the first inlet line 111, the first traction control valve TCV1, and the first inlet valve FRIV.

[0034] The third inlet line 113 is not pressurized by the actuator 150; only the first inlet line 111 and the second inlet line 112 are pressurized by the actuator 150. Therefore, according to the control method of the auxiliary braking system 100 of this disclosure, two-channel pressurization control can be performed.

[0035] Output lines 121, 122, and 123 can be connected to points on inlet lines 111, 112, and 113, such that at least a portion of the brake fluid inlet lines 111, 112, and 113 is diverted. Output lines 121, 122, and 123 may include a first output line 121, a second output line 122, and a third output line 123.

[0036] One end of the first output line 121 can be connected to a branch on the first inlet line 111 formed after the first inlet valve FRIV, and the other end can be connected to the inlet of the first pump SP1.

[0037] The first outlet valve FROV is located at a point on the first output line 121, and the first outlet valve FROV can regulate the opening / closing of the first output line 121. The first outlet valve FROV can be configured to be normally closed. Therefore, in the non-powered mode where the auxiliary braking signal is not applied, the first outlet valve FROV is closed. When the first outlet valve FROV is open, at least a portion of the brake fluid that has been pressurized and flows through the first inlet line 111 can be discharged into the first output line 121. That is, the hydraulic pressure transmitted to the first wheel brake FR can be reduced.

[0038] The first accumulator A1 may be further disposed at another point on the first output line 121 formed after the first outlet valve FROV. The first accumulator A1 may temporarily contain part or all of the brake fluid transmitted from the first output line 121. Therefore, damage to the first output line 121 due to fluctuations in brake fluid can be minimized. In this case, damage to the first output line 121 may include fatigue, deformation, wear, etc., occurring in at least a portion of the line when the line is exposed to continuous fluctuations for an extended period.

[0039] The descriptions of the second output line 122, the second outlet valve FLOV, and the second accumulator A2 are respectively referred to the descriptions of the first output line 121, the first outlet valve FLOV, and the first accumulator A1.

[0040] One end of the third output line 123 can be connected to a point on the third inlet line 113, and the other end can be connected to the first output line 121. The third output line 123 and the first output line 121 can be formed at a point after the first outlet valve FROV. Therefore, the brake fluid transmitted by the third output line 123 can merge with the brake fluid flowing through the first output line 121.

[0041] The third output line 123 may be connected to one or more of the first output line 121 and the second output line 122. The brake fluid transmitted by the third output line 123 may accumulate in at least one of the first accumulator A1 and the second accumulator A2.

[0042] When driver intervention is present, the auxiliary braking system 100 according to this disclosure can generate the maximum braking force of the vehicle by controlling the rear wheel high-pressure switching valve HSV3 connected to the third wheel brake RL and accumulators A1 and A2.

[0043] The rear wheel high-pressure switching valve HSV3 is located at a point on the third output line 123, and the opening / closing of the third output line 123 can be adjusted. The rear wheel high-pressure switching valve HSV3 is normally closed. Therefore, in non-powered mode, the rear wheel high-pressure switching valve HSV3 is closed.

[0044] When the rear wheel high-pressure switching valve HSV3 is opened, at least a portion of the brake fluid flowing through the third inlet line 113 is diverted to the third outlet line 123. Therefore, the hydraulic pressure transmitted to the third wheel brake RL can be reduced.

[0045] When there is no driver intervention, the hydraulic pressure supplied from the reservoir 10 to the auxiliary braking system 100 is blocked. Therefore, the auxiliary braking system 100 according to this disclosure can use an electric parking brake to replace the braking force of the third wheel brake RL, and can transfer the brake fluid transmitted to the third wheel brake RL to the first wheel brake FR and the second wheel brake FL.

[0046] When the rear wheel high-pressure switching valve HSV3 opens, at least a portion of the brake fluid flowing through the third inlet line 113 can be diverted to the third outlet line 123 and merge with the brake fluid flowing through the first outlet line 121 and the second outlet line 122. The first accumulator A1 and the second accumulator A2 can temporarily hold part or all of the brake fluid transmitted from the first outlet line 121 and the second outlet line 122. Therefore, the actuator 150 can increase the pressure of the brake fluid transmitted to the first wheel brake FR and the second wheel brake FL by receiving the brake fluid transmitted to the third wheel brake RL.

[0047] The first oil chamber 131 may be further disposed on the first inlet line 111. In this case, the first oil chamber 131 is disposed before the first traction control valve TCV1. The first oil chamber 131 may temporarily contain at least a portion of the brake fluid discharged from the main braking system 20. Since the hydraulic pressure supplied from the reservoir 10 to the auxiliary braking system 100 is blocked when there is no driver braking interference, at least a portion of the brake fluid contained in the oil chambers 131 and 132 may be supplied to the actuator 150.

[0048] One end of circulation lines 141 and 142 is connected to oil chambers 131 and 132, and the other end is connected to output lines 121 and 122 adjacent to the inlets of pumps SP1 and SP2. In this case, the point where the other end of circulation lines 141 and 142 connects to output lines 121 and 122 can preferably be formed after accumulators A1 and A2. Therefore, brake fluid discharged from accumulators A1 and A2 and oil chambers 131 and 132 is supplied to actuator 150, thus providing a sufficient amount of brake fluid for driving actuator 150.

[0049] The first high-pressure switching valve HSV1 is located at a point on the first circulation line 141 and can adjust the opening / closing of the first circulation line 141. The first high-pressure switching valve HSV1 can be configured to be normally closed. Therefore, in non-powered mode, the first high-pressure switching valve HSV1 is closed. When the first high-pressure switching valve HSV1 is open, at least a portion of the brake fluid contained in the first oil chamber 131 can be supplied to the actuator 150.

[0050] The description of the second circulation line 142 and the second high-pressure switching valve HSV2 refers to the description of the first circulation line 141 and the first high-pressure switching valve HSV1.

[0051] Figure 2 This is a flowchart of a method for controlling an auxiliary braking system of an electro-hydraulic brake according to an embodiment of the present invention.

[0052] refer to Figure 2 When the main braking system 20 fails during automatic driving, or when the main braking system 20 fails when the driver manually intervenes in braking, the auxiliary braking system 100 can be operated.

[0053] The control unit can determine whether at least some components of the main braking system 20 have failed (S201). When the control unit determines that the main braking system 20 has failed, the control unit can send an auxiliary braking signal to the auxiliary braking system 100.

[0054] The auxiliary braking system 100 can control the opening of the rear wheel high pressure switching valve HSV3 (S203). By opening the rear wheel high pressure switching valve HSV3, the braking force of the vehicle can be increased after the hydraulic pressure of the third wheel brake RL has been removed and brake fluid has been delivered to the front wheels.

[0055] Regarding the timing of the opening of the rear wheel high-pressure switching valve HSV3, when the auxiliary braking system 100 is activated, the rear wheel high-pressure switching valve HSV3 can be controlled to always be open. In this case, even if the driver does not interfere with braking, no pressure will be generated at the third wheel brake RL. When the driver interferes with braking, the responsiveness of the auxiliary braking system 100 can be improved because accumulators A1 and A2 are immediately charged. However, since the rear wheel high-pressure switching valve HSV3 is always controlled, the current consumption may increase.

[0056] Regarding the timing of the opening of the rear wheel high-pressure switching valve HSV3, HSV3 can be controlled to selectively open only when the driver intervenes with braking. Driver intervention can be determined using the pedal depressor or a pressure sensor in the main braking system 20. In this case, since HSV3 opens after driver intervention with braking, the responsiveness in removing pressure generated at the third wheel brake RL may be worse. However, since HSV3 is controlled when necessary, current consumption can be reduced.

[0057] The auxiliary braking system 100 can determine whether there is driver interference during rapid braking (S205). When driver interference is present, the auxiliary braking system 100 can control the first traction control valve TCV1 and the second traction control valve TCV2 to close, and can drive the actuator 150 (S207).

[0058] The auxiliary braking system 100 can control the opening of the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2. That is, the auxiliary braking system 100 of this disclosure can generate maximum braking force in the vehicle by opening all of the plurality of high-pressure switching valves HSV1, HSV2 and HSV3 and closing all of the plurality of traction control valves TCV1 and TCV2.

[0059] When multiple high-pressure switching valves HSV1, HSV2, and HSV3 remain open during rapid braking, accumulators A1 and A2 may not be emptied, depending on the master cylinder pressure. Since the inlets of pumps SP1 and SP2 are connected to circulation lines 141 and 142, the hydraulic pressure at the inlets of pumps SP1 and SP2 increases when the brake pedal is depressed. Therefore, it is impossible to obtain brake fluid from accumulators A1 and A2, thus potentially resulting in accumulators A1 and A2 not being emptied.

[0060] The following process typically occurs in the early stages of driver braking intervention: by opening the rear wheel high pressure switching valve HSV3, the hydraulic pressure of the vehicle that has removed the third wheel brake RL can be increased and brake fluid can be delivered to the front wheels.

[0061] The auxiliary braking system 100 of this disclosure can control a first high-pressure switching valve HSV1 and a second high-pressure switching valve HSV2 using the pressure of the master cylinder and the driver's braking intervention time to effectively generate braking force in the vehicle. The auxiliary braking system 100 can determine a first condition (defined as the master cylinder pressure being greater than a preset pressure) and a second condition (defined as the driver's braking intervention time being less than a preset time) (S209). For example, when the master cylinder pressure exceeds 2 to 5 bar, the first condition can be set to be met, and when the driver's braking intervention time is less than 100 to 300 ms, the second condition can be set to be met. In this document, the intervention time is the duration of the driver's braking intervention.

[0062] When one or more of the first and second conditions are met, the auxiliary braking system 100 can perform pattern control or sequential control (S211) on the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2. This can resolve the issue of accumulators A1 and A2 not being emptied, alleviate the instability of the rear wheels caused by the residual pressure in accumulators A1 and A2, and effectively generate braking force in the vehicle.

[0063] Mode control involves opening and closing high-pressure switching valves HSV1, HSV2, and HSV3 at predetermined intervals. For example, they can be repeatedly opened and closed by applying a 50% duty cycle to HSV1, HSV2, and HSV3. Sequential control involves opening and closing high-pressure switching valves HSV1, HSV2, and HSV3 sequentially.

[0064] When neither the first condition nor the second condition is met, the auxiliary braking system 100 can open the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2 (S213).

[0065] Figure 3 This is a flowchart of a method for controlling an auxiliary braking system of an electro-hydraulic brake according to another embodiment of the present invention.

[0066] Figure 3 This is a control method for the auxiliary braking system 100 that intervenes in braking when the driver is braking slowly rather than braking rapidly.

[0067] The descriptions of the processes for determining a fault in the main braking system 20 (S301), controlling the opening of the rear wheel high-pressure switching valve HSV3 (S303), determining whether there is driver interference during braking (S305), and controlling the closing of the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2 and driving the actuator 150 (S307) are provided below. Figure 2 The corresponding processes are S201 to S207.

[0068] When the auxiliary braking system 100 controls the high-pressure switching valves HSV1, HSV2 and HSV3, a disconnection may occur in the pedal feel due to the opening of the high-pressure switching valves HSV1, HSV2 and HSV3 and the movement of the brake fluid.

[0069] To address this issue, the auxiliary braking system 100 can control the closure of the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2. That is, by closing the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2, opening the rear wheel high-pressure switching valve HSV3, and closing all multiple traction control valves TCV1 and TCV2, the auxiliary braking system 100 can ensure smooth pedaling during slow braking. Subsequently, based on changes in master cylinder pressure, the pedal feel can be adjusted by opening or executing mode control of the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2.

[0070] The auxiliary braking system 100 of this disclosure can use the pressure change of the master cylinder and the driver's braking intervention time to control the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2 to smooth the braking pedal. The auxiliary braking system 100 can determine a third condition and a fourth condition, the third condition being defined as the pressure increase of the master cylinder being less than a preset value, and the fourth condition being defined as the driver's braking intervention time being less than a preset time (S309).

[0071] When one or more of the third and fourth conditions are met, the auxiliary braking system 100 can close the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2 (S311).

[0072] When neither the third nor the fourth condition is met, the auxiliary braking system 100 can open or execute mode control of the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2 (S313). That is, when the pressure increase of the master cylinder is large, braking force can be generated in the vehicle by controlling the first high-pressure switching valve HSV1 and the second high-pressure switching valve HSV2.

[0073] According to this disclosure, the control method for the electro-hydraulic brake has the effect of reducing manufacturing costs and increasing assembly convenience by controlling an auxiliary braking system that can perform 2-channel pressurization control and 1-channel depressurization control.

[0074] According to embodiments of this disclosure, when the driver interferes with braking under redundant conditions, the control method for the electro-hydraulic brake can generate braking force in the vehicle by using a front wheel-auxiliary braking system and a rear wheel-electric parking brake.

[0075] Although exemplary embodiments of this disclosure have been described for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions are possible without departing from the spirit and scope of the claimed invention. Therefore, exemplary embodiments of this disclosure have been described for the sake of brevity and clarity. The scope of the technical concept of these embodiments is not limited to the illustrations. Therefore, those skilled in the art will understand that the scope of the claimed invention is not limited to the embodiments explicitly described above, but rather to the technical solutions and their equivalents.

Claims

1. A control method for an electro-hydraulic brake, the electro-hydraulic brake including an auxiliary braking system that generates braking force in a vehicle when the main braking system fails, the control method comprising: Determine whether the main braking system has failed; When the main braking system is determined to have failed, the rear wheel high pressure switching valve HSV is opened, wherein the rear wheel high pressure switching valve HSV is connected to the rear wheel of the main braking system and the low pressure accumulator LPA of the auxiliary braking system. Determine if the driver interfered with the braking; as well as Control the auxiliary braking system to generate braking force in the vehicle. The auxiliary braking system includes: Close multiple traction control valves (TCVs), which regulate the opening and closing of the front wheel inlet lines of the auxiliary braking system; and The actuator that operates the auxiliary braking system.

2. The control method according to claim 1, wherein, The auxiliary braking system also includes controlling multiple HSVs installed on the pipeline connecting the actuator and the oil chamber of the auxiliary braking system when the driver's braking interference time is less than a preset time.

3. The control method according to claim 2, wherein, Controlling the auxiliary braking system also includes determining a first condition and a second condition. The first condition is defined as the pressure of the master cylinder of the main braking system being greater than a preset pressure, and the second condition is defined as the driver's braking intervention time being less than a preset time.

4. The control method according to claim 3, wherein, Controlling multiple HSVs includes turning on the multiple HSVs when neither the first condition nor the second condition is met.

5. The control method according to claim 3, wherein, Controlling multiple HSVs includes performing mode control on the multiple HSVs when one or more of the first condition and the second condition are met.

6. The control method according to claim 2, wherein, Controlling the auxiliary braking system also includes determining a third condition and a fourth condition. The third condition is defined as the situation where the pressure increase of the master cylinder of the main braking system is less than a preset pressure increase, and the fourth condition is defined as the situation where the driver's braking intervention time is less than a preset time.

7. The control method according to claim 6, wherein, Controlling multiple HSVs includes shutting down the multiple HSVs when one or more of the third and fourth conditions are met.

8. The control method according to claim 6, wherein, Controlling multiple HSVs includes turning on the multiple HSVs or performing mode control on the multiple HSVs when neither the third condition nor the fourth condition is met.

9. The control method according to claim 1, wherein, Opening the rear wheel HSV includes keeping the rear wheel HSV open when the main braking system is determined to have failed.

10. The control method according to claim 1, wherein, Deploying the rear wheel HSV includes deploying the rear wheel HSV when the main braking system is determined to have failed and there is driver braking interference.

11. The control method according to claim 1, wherein, The driver's braking interference is determined using one or more of the pedal depressors and pressure sensors of the main braking system.

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