Patent Publication Number: US-2023145707-A1

Title: Electronic brake for vehicle and control method therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0152594, filed on Nov. 8, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to an electronic brake for a vehicle and a control method therefor. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     An electronic brake forms a braking force for a wheel brake mechanism using a motor. A brake device including a motor pressurizes a working fluid within a hydraulic circuit of the electronic brake. The pressurized working fluid is selectively carried to a plurality of wheel brake mechanisms through a flow pathway which is formed by opening and closing a plurality of valves on the hydraulic circuit of the electronic brake. The plurality of wheel brake mechanisms slows down or stops wheels by using a hydraulic pressure of the carried working fluid. 
     An auxiliary brake device was proposed which is configured to generate a braking pressure by serving as a backup for a main brake device of a vehicle when a failure occurs to the main brake device. As a backup for a main controller for controlling the main brake device, an auxiliary controller for controlling the auxiliary brake device may be mounted along with the auxiliary brake device. The auxiliary brake system is configured to go into cooperative control, if the power output of the main brake device does not meet a set condition. Here, the phrase “the power output of the main brake device does not meet a set condition” may mean that something is wrong with the main brake device. 
     However, even with an auxiliary brake device, a brake device for a vehicle is not able to generate a braking force required to safely run the vehicle, if something is wrong with the auxiliary brake device. 
     SUMMARY 
     According to at least one aspect, the present disclosure provides a control method for an electronic brake for a vehicle, the electronic brake comprising a first brake device including a first pressurizer, that is configured to supply hydraulic pressure to a plurality of wheel brakes, a second brake device including a second pressurizer, that is connected between a first wheel brake group including at least part of the plurality of wheel brakes and configured to supply hydraulic pressure to the first wheel brake group, and a control unit including a first controller for controlling the first brake device and a second controller for controlling the second brake device, the method comprising: determining, by the control unit, whether the first brake device is operating normally; determining, by the control unit, whether a connecting flow path connecting an outlet of the first pressurizer and an outlet of the second pressurizer is closed; calculating, by the control unit, a first required braking force which the first wheel brake group needs to apply to the vehicle; and a pressure increasing step in which, based on a determination that the first brake device is operating normally and the connecting flow path is closed, the second controller controls the second brake device so that the second pressure device pressurizes fluid, based on the first required braking force being greater than a braking force applied to the vehicle by the first wheel brake group. 
     According to another aspect, the present disclosure provides an electronic brake for a vehicle, the electronic brake comprising: a first brake device including a first pressurizer, that is configured to supply hydraulic pressure to a plurality of wheel brakes; a second brake device including a second pressurizer, that is connected between a first wheel brake group including at least part of the plurality of wheel brakes and configured to supply hydraulic pressure to the first wheel brake group; and a control unit including a receiver for receiving at least one of a stroke signal of a brake pedal or a brake signal generated by an autonomous driving system, a first controller for controlling the first brake device, a second controller for controlling the second brake device, a device status determination unit for determining whether the first brake device is operating normally, a connection status determination unit for determining whether a connecting flow path connecting an outlet of the first pressurizer and an outlet of the second pressurizer is closed, and a required braking force calculator for calculating a first required braking force which the first wheel brake group needs to apply to the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a hydraulic circuit diagram of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
         FIG.  2    is a sequence diagram of a control method according to an embodiment of the present disclosure. 
         FIG.  3    is a block diagram schematically showing a configuration of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure are able to stably generate a required braking force by controlling an auxiliary brake device by an auxiliary controller, if a flow path on the auxiliary brake device that connects a main brake device and a wheel brake is unintentionally closed. 
     The aspects of the present disclosure are not limited to the foregoing, and other aspects not mentioned herein will be able to be clearly understood by those skilled in the art from the following description. 
     Hereinafter, some exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, like reference numerals preferably designate like elements, although the elements are shown in different drawings. Further, in the following description of some embodiments, a detailed description of known functions and configurations incorporated therein will be omitted for the purpose of clarity and for brevity. 
     Additionally, various terms such as first, second, A, B, (a), (b), etc., are used solely to differentiate one component from the other but not to imply or suggest the substances, order, or sequence of the components. Throughout this specification, when a part ‘includes’ or ‘comprises’ a component, the part is meant to further include other components, not to exclude thereof unless specifically stated to the contrary. The terms such as ‘unit’, ‘module’, and the like refer to one or more units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof. 
       FIG.  1    is a hydraulic circuit diagram of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     Referring to  FIG.  1   , an electronic brake for a vehicle that is controlled by a control method according to an embodiment of the present disclosure includes a first brake device  110 , a second brake device  120 , and a control unit  150 . 
     A plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  is configured to restrict the rotation of the wheels by using a hydraulic pressure generated by the brake devices. The plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  may be mounted to different wheels and apply a braking force to the mounted wheels. The wheel brakes w 1 , w 2 , w 3 , and w 4  may be caliper-type brakes or drum-type brakes. In this disclosure, wheel brakes w 1  and w 2  mounted to front wheels are referred to as front wheel brakes w 1  and w 2 , and wheel brakes w 3 , and w 4  mounted to rear wheels are referred to as rear wheel brakes w 3  and w 4 . The plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  is configured to receive a hydraulic pressure from the first brake device  110  and/or the second brake device  120  and apply a required braking force to the vehicle. The required braking force is a target braking force which the electronic brake of the vehicle needs to apply to the vehicle, which may be calculated based on a stroke signal generated by a pedal stroke sensor  112   a  mounted on a brake pedal  112  or a brake signal generated by an autonomous driving system ( 310  of  FIG.  3   ). 
     The first brake device  110  is configured to supply hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . The first brake device  110  includes a first pressurizer  111  configured to pressurize fluid, and the entire or part of a first valve group configured to selectively supply hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . 
     The first pressurizer  111  includes all or part of a first motor  111   a , a piston  111   b , and a hydraulic chamber  111   c  and  111   d . The first pressurizer  111  may be driven by the first motor  111   a . The first pressurizer  111  may include a power train (not shown) that converts a torque of the first motor  111   a  into a translational force on the piston  111   b . The power train is a mechanism that converts rotary motion into translational motion, for example, by using a ball screw and a screw nut. The piston  111   b  may be configured to move forward or backward depending on the direction of rotation of the first motor  111   a . In this disclosure, the opposite side of the first motor  111   a  is referred to as “front side”, and the side of the first motor  111   a  is referred to as “rear side”. A hydraulic chamber  111   c  and  111   d , which is a space where fluid is pressurized, may be divided into two by the piston  111   b . A hydraulic chamber  111   c  and  111   d  positioned at the rear of the piston  111   b  is referred to as a first hydraulic chamber  111   c , and a hydraulic chamber  111   c  and  111   d  positioned at the front of the piston  111   b  is referred to as a second hydraulic chamber  111   d . When the piston  111   b  moves backward, a fluid in the first hydraulic chamber  111   c  may be pressurized, and the fluid may be supplied into the second hydraulic chamber  111   d . When the piston  111   b  moves forward, a fluid in the second hydraulic chamber  111   d  may be pressurized, and the fluid may be supplied into the first hydraulic chamber  111   c . However, the pressurizer of this disclosure is not limited to such a double-acting pressurizer. The pressurizer may be a single-acting pressurizer, for example, which is configured such that fluid is not pressurized in the hydraulic chamber  111   c  and fluid is supplied to the second hydraulic chamber  111   d . The first pressurizer  111  may include a cylinder whose inner periphery adjoins the outer periphery of the piston  111   b . The piston  111   b  may slide to the front or rear of the cylinder depending on the direction of rotation of the first motor  111   a.    
     The first valve group may include a plurality of solenoid valves that are configured such that their open and closed states vary with applied current. A fluid flow pathway in the first brake device  110  may vary depending on the open and closed states of the first valve group, that is, whether they are open or closed or how much they are open or closed. 
     The second brake device  120  may produce a hydraulic pressure equivalent to the required braking force by serving as a backup for the first brake device  110 . When the first brake device  110  is operating normally, the first brake device  110  may generate a hydraulic pressure equivalent to the required braking force, and when the first brake device  110  is not operating normally, the second brake device  120  may generate a braking force by serving as a backup for the first brake device  110 . The second brake device  120  is configured to supply hydraulic pressure to a first wheel brake group w 1  and w 2 . The first wheel brake group w 1  and w 2  includes at least part of the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . In this disclosure, part of the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 , exclusive of the first wheel brake group w 3  and w 4 , is referred to as a second wheel brake group w 3  and w 4 . The first wheel brake group w 1  and w 2  according to an embodiment of the present disclosure includes front wheel brakes w 1  and w 2 , and the second wheel brake group w 3  and w 4  includes rear wheel brakes w 3  and w 4 . The first hydraulic chamber  111   c  may communicate fluid to the front wheel brakes w 1  and w 2 , and the second hydraulic chamber  111   d  may communicate fluid to the rear wheel brakes w 3  and w 4 . The second brake device  120  includes a second pressurizer  121  configured to pressurize fluid, and the entire or part of a second valve group configured to selectively supply hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4 . The second brake device  120  is connected between the first wheel brake group w 1  and w 2  and the first brake device  110 . 
     The second pressurizer  121  includes all or part of a second motor  121   a  and the hydraulic chamber  111   c  and  111   d . The second pressurizer  121  may include a first pump and a second pump that are configured to alternately pressurize fluid as an eccentric shaft of the second motor  121   a  rotates. The second pressurizer  121  may pressurize a fluid supplied from an oil reservoir  140  and discharge it to the wheel brakes w 1 , w 2 , w 3 , and w 4 . An inlet flow path valve portion  126  may be disposed on a flow path connecting the second pressurizer  121  and the oil reservoir  140 . When the inlet flow path valve unit  126  is opened, fluid may be supplied from the oil reservoir  140  to the second pressurizer  121 . 
     In this disclosure, a flow path connecting an outlet of the first pressurizer  111  and an outlet of the second pressurizer  121  is referred to as a connecting flow path  130 . The second valve group may include a block valve unit  125  disposed on the connecting flow path  130 . The block valve unit  125  may include a check valve that allows fluid to flow from the outlet of the first pressurizer  111  to the first wheel brake group w 1  and w 2  and stops the fluid from flowing from the first wheel brake group w 1  and w 2  to the first pressurizer  111 . When the block valve unit  125  is closed, a high-pressure fluid pressurized by the second pressurizer  121  may be supplied to the first wheel brake group w 1  and w 2  without leaking to the first brake device  110 . When the second brake device  120  forms a braking pressure by serving as a backup for the first brake device  110 , the control unit  150  may close the block valve unit  125  and drive the second motor  121   a  of the second pressurizer  121 , in order to increase the braking force. Moreover, the first controller  151  may control the first pressurizer  111  so that the first pressurizer  111  pressurizes fluid. In this way, the fluid pressurized by the second pressurizer  121  and the fluid pressurized by the first pressurizer  111  may be delivered to the first wheel brake group w 1  and w 2  past the check valve. The block valve unit  125  may be a normal open-type solenoid valve which is open at normal times. The “normal times” refer to times during which the current applied to the block valve unit  125  is no higher than a predetermined value, for example. When the first brake device  110  is not operating normally, the control unit  150  may apply a current to the block valve unit  125  to close the block valve unit  125  and control the second pressurizer  121  and/or the second valve group. 
     A split valve  114  may be disposed on a flow path connecting the second wheel brake group w 3  and w 4  and the outlet of the first pressurizer  111  on the side of the first wheel brake group w 1  and w 2 . The split valve  114  may be disposed on a flow path connecting the first hydraulic chamber  111   c  and the rear wheel brakes w 3  and w 4 . When the split valve  114  is opened, a hydraulic pressure formed in the first hydraulic chamber  111   c  may be delivered to the rear wheel brakes w 3  and w 4 , and a hydraulic pressure formed in the second hydraulic chamber  111   d  may be delivered to the front wheel brakes w 1  and w 2 . On the contrary, when the split valve  114  is closed, the hydraulic pressure formed in the first hydraulic chamber  111   c  is not delivered to the rear wheel brakes w 3  and w 4 , and the hydraulic pressure formed in the second hydraulic chamber  111   d  is not delivered to the front wheel brakes w 1  and w 2 . 
     The control unit  150  includes a first controller  151  for controlling the first brake device  110  and a second controller  152  for controlling the second brake device  120 . The first controller  151  may control the open and closed states of the first valve group by adjusting the current applied to the first valve group. The first controller  151  may control the rotation of the first motor  111   a  by adjusting the phase or intensity of the current supplied to the first motor  111   a . Likewise, the second controller  152  may control the open and closed states of the second valve group and the rotation of the second motor  121   a.    
     The first controller  151  and the second controller  152  of the control unit  150  according to an exemplary embodiment of the present disclosure may be a processor (e.g., computer, microprocessor, CPU, ASIC, circuitry, logic circuits, etc.). Each controller may be implemented by a non-transitory memory storing, e.g., a program(s), software instructions reproducing algorithms, etc., which, when executed, performs various functions described hereinafter, and a processor configured to execute the program(s), software instructions reproducing algorithms, etc. Herein, the memory and the processor may be implemented as separate semiconductor circuits. Alternatively, the memory and the processor may be implemented as a single integrated semiconductor circuit. The processor may embody one or more processor(s). 
       FIG.  2    is a sequence diagram of a control method according to an embodiment of the present disclosure. 
     Referring to  FIG.  2   , the control unit  150  may determine whether the first brake device  110  is operating normally (S 210 ). For example, the control unit  150  may receive a pedal stroke signal and a pressure measurement from a pressure sensor disposed on the first brake device  110 , and determine the state of the first brake device  110  by comparing whether the pressure measurement has a value equivalent to a required braking force calculated based on the pedal stroke signal. When the first brake device  110  is not operating normally, the second controller  152  controls the second brake device  120  so that the second brake device  120  supplies hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  by serving as a backup for the first brake device  110  (S 215 ). When the first brake device  110  is operating normally, the control unit  150  determines whether the connecting flow path  130  is closed (S 220 ). For example, if a pressure measured at the connecting flow path  130  is lower than a pressure corresponding to the current applied to the first motor  111   a  by the first controller  151 , the control unit  150  may determine that the connecting flow path  130  is closed. If it is determined that the connecting flow path  130  is not closed, the first controller  151  controls the first brake device  110  so that the first brake device  110  supplies hydraulic pressure to the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  (S 225 ). If the connecting flow path  130 , which is a flow path connecting the first brake device  110  and the first wheel brake group w 1  and w 2 , is closed, the hydraulic pressure formed in the first brake device  110  is not delivered to the first wheel brake group w 1  and w 2 . In this case, even if the first brake device  110  is operating normally, the second brake device  120  needs to deliver hydraulic pressure to the first wheel brake group w 1  and w 2  by serving as a backup for the first brake device  110 . The connecting flow path  130  may be closed when a plunger (not shown) of the block valve unit  125  gets stuck, for example. This stucking may occur when the second controller  152  does not apply a proper amount of current to the block valve unit  125  due to foreign substances clogging the inside of the block valve unit  125  or a failure in the circuit of the second controller  152 . 
     The control unit  150  calculates a first required braking force which the first wheel brake group w 1  and w 2  needs to apply to the vehicle (S 240 ). If it is determined that the first brake device  110  is operating normally and the connecting flow path  130  is closed, the control unit  150  determines whether the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  needs to be increased (S 261 ). If the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  is greater than the first required braking force, the control unit  150  may determine that the braking force needs to be increased. Once it is determined that the braking force needs to be increased, the second controller  152  controls the second brake device  120  so that the inlet flow path valve unit  126  is opened (S 272 ). As the inlet flow path valve unit  126  is opened, fluid may be supplied from the oil reservoir  140  to the second pressurizer  121 . The second controller  152  controls the second brake device  120  so that the second pressurizer  121  pressurizes fluid (S 273 ). The second controller  152  may drive the second motor  121   a  so that second pressurizer  121  pressurizes fluid. In this way, the fluid pressure formed in the second pressurizer  121  may be delivered to the wheel brakes w 1 , w 2 , w 3 , and w 4 . 
     If it is determined that the first brake device  110  is operating normally and the connecting flow path  130  is closed, the control unit  150  determines whether the braking force applied to the vehicle by the wheel brake group w 1  and w 2  needs to be decreased (S 262 ). If the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  is smaller than the first required braking force, the control unit  150  may determine that the braking force needs to be decreased. Once it is determined that the braking force needs to be decreased, the first controller  151  or the second controller  152  controls the second brake device  120  so that fluid is communicated between the first wheel brake group w 1  and w 2  and the oil reservoir  140 . For example, the second controller  152  controls the second brake device  120  so that a first outlet valve unit OV is opened (S 282 ). In this way, the fluid in the first wheel brake group w 1 , w 2 , w 3 , and w 4  is delivered to the oil reservoir  140 , thereby reducing the hydraulic pressure in the first wheel brake group w 1 , w 2 , w 3 , and w 4 . 
     In the control method according to an embodiment of the present disclosure, the control unit  150  may determine whether the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  needs to be urgently increased (S 251 ). The control unit  150  may determine whether the braking force needs to be urgently increased based on a brake signal generated by the autonomous driving system  310  or a pedal stroke signal generated by the pedal stroke sensor  112   a . For example, if the stroke speed of the brake pedal  112  is equal to or higher than a preset value based on the pedal stroke signal, the control unit  150  may determine that the braking force needs to be urgently increased. For example, the brake signal may be an emergency brake signal the autonomous driving system  310  generates when a lidar sensor (not shown) detects a pedestrian near the vehicle. 
     Once it is determined that the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  needs to be urgently increased, the first controller  151  controls the first brake device  110  so that the first brake device  110  supplies hydraulic pressure to the first wheel brake group w 1  and w 2  (S 271 ). Moreover, the steps S 272  and S 273  are performed by the control unit  150 . That is, the control unit  150  controls the second pressurizer  121  and the like so that the second pressurizer  121  pressurizes fluid. In this case, since the first brake device  110  is operating normally, a high-pressure fluid pressurized by the first brake device  110  may be delivered to the first wheel brake group w 1  and w 2  past the check valve on the block valve unit  125 . Along with the hydraulic pressure formed by the second hydraulic device in the steps S 271  and S 273 , the hydraulic pressure formed by the first hydraulic device is delivered to the first wheel brake group w 1  and w 2 . In this way, a high hydraulic pressure may be supplied to the wheel brakes w 1 , w 2 , w 3 , and w 4  when there is a need to urgently increase the braking force. 
     In the control method according to an embodiment of the present disclosure, the control unit  150  may determine whether the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  needs to be urgently decreased (S 252 ). For example, the control unit  150  may determine that the braking force needs to be urgently decreased if the stroke speed of an accelerator pedal is equal to or higher than a preset value. Once it is determined that the braking force applied to the vehicle by the first wheel brake group w 1  and w 2  needs to be urgently decreased, the second controller  152  controls the second brake device  120  so that a first inlet valve unit IV is closed (S 281 ). Once the first inlet valve unit IV is closed, no hydraulic pressure is delivered to the wheel brakes w 1 , w 2 , w 3 , and w 4  from the first pressurizer  111  or the second pressurizer  121 . Also, the step S 282  is performed by the control unit  150 . Since the first inlet valve unit IV is closed and the first outlet valve unit OV is opened, the hydraulic pressure in the first wheel brake group w 1  and w 2  may be rapidly reduced. 
     In the control method according to an embodiment of the present disclosure, if it is determined that the first brake device  110  is operating normally and the connecting flow path  130  is closed, the first controller  151  controls the first brake device  110  so that the split valve  114  is closed (S 231 ). The first controller  151  controls the first brake device  110  so as to deliver hydraulic pressure to the second wheel brake group w 3  and w 4  (S 232 ). Unless there is no failure that causes the flow path connecting the first pressurizer  111  and the second wheel brake group w 3  and w 4  to be unintentionally closed, the first pressurizer  111  may supply hydraulic pressure to the second wheel brake group w 3  and w 4  (S 231  and S 232 ). 
     According to the above-described control method, even if a failure occurs in which the block valve unit  125  gets stuck while closed, the electronic brake for a vehicle may stably generate a required braking force. 
       FIG.  3    is a block diagram schematically showing a configuration of an electronic brake for a vehicle according to an embodiment of the present disclosure. 
     The above-described control method may be performed by an electronic brake for a vehicle according to an embodiment of the present disclosure. The electronic brake for a vehicle according to the embodiment to be described below may include a configuration of the electronic brake for a vehicle that is controlled by the above-described control method. The configuration and functions of the electronic brake for a vehicle to be described below are identical to the configuration and functions of the electronic brake for a vehicle that is controlled by the above-described control method, so redundant description will be omitted. 
     Referring to  FIG.  3   , an electronic brake for a vehicle according to an embodiment of the present disclosure includes a first brake device  110 , a second brake device  120 , and a control unit  150 . 
     The control unit  150  may include all or part of a receiver  153 , a first controller  151 , a second controller  152 , a device status determination unit  154 , a connection status determination unit  155 , a required braking force calculator  156 , and an emergency determination unit  157 . According to an exemplary embodiment of the present disclosure, the control unit  150  may include a processor (e.g., computer, microprocessor, CPU, ASIC, circuitry, logic circuits, etc.) and an associated non-transitory memory storing software instructions which, when executed by the processor, provides the functionalities of the first controller  151 , the second controller  152 , the device status determination unit  154 , the connection status determination unit  155 , the required braking force calculator  156 , and the emergency determination unit  157 . 
     The receiver  153  receives at least one of a stroke signal of the brake pedal  112  and a brake signal generated by the autonomous driving system  310 . A hydraulic sensor of the first brake device  110  may send information on a pressure value at a predetermined position inside the first brake device  110 . The receiver  153  may receive this information on the pressure value. The required braking force calculator  156  calculates a first required braking force which the first wheel brake group w 1  and w 2  needs to apply to the vehicle. The required braking force calculator  156  may calculate a required braking force based on at least one of the stroke signal and the brake signal. The device status determination unit  154  determines whether the first brake device  110  is operating normally. If a hydraulic pressure at a predetermined position on the first brake device  110  is not equivalent to the first required braking force, determination unit  154  may determine that the first brake device  110  is not operating normally. The hydraulic pressure at the predetermined position on the first brake device  110  equivalent to the first required braking force may be stored in the form of a look-up table (LUT) in a memory (not shown) of the control unit  150 . The connection status determination unit  155  determines whether the connecting flow path  130  is closed or not. For example, if a pressure measured at the connecting flow path  130  is lower than a pressure value corresponding to the current applied to the first motor  111   a  by the controller  151 , the connection status determination unit  155  may determine that the connecting flow path  130  is closed. The control unit  150  may determine whether the braking force applied to the vehicle by the plurality of wheel brakes w 1 , w 2 , w 3 , and w 4  needs to be urgently increased or decreased, based on at least one of the stroke signal and the brake signal. For example, if the stroke speed of the brake pedal  112  is equal to or higher than a preset value based on the stroke signal of the brake pedal  112 , the emergency determination unit  157  may determine that the braking force needs to be urgently increased. The brake signal may be an emergency brake signal the autonomous driving system  310  generates when a lidar sensor detects a pedestrian near the vehicle. If the stroke speed of the accelerator pedal is equal to or higher than a preset value, the control unit  150  may determine that the braking force needs to be urgently decreased. 
     An electronic brake for a vehicle and a control method therefor according to an embodiment of the present disclosure have the effect of stably generating a required braking force by controlling an auxiliary brake device by an auxiliary controller, if a flow path on the auxiliary brake device that connects a main brake device and a wheel brake is unintentionally closed. 
     Although exemplary embodiments of the present disclosure have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the idea and scope of the claimed invention. Therefore, exemplary embodiments of the present disclosure have been described for the sake of brevity and clarity. The scope of the technical idea of the present embodiments is not limited by the illustrations. Accordingly, one of ordinary skill would understand the scope of the claimed invention is not to be limited by the above explicitly described embodiments but by the claims and equivalents thereof.