BRAKE CONTROL DEVICE AND METHOD FOR A VEHICLE

Abstract

Brake control device for a vehicle which includes: a pedal travel sensing unit (10) designed to sens the pedal travel of a brake pedal; a pedal simulator pressure sensing unit (20) configured to sensing a pressure from a pedal simulator that provides a reaction force in response to the force applied to the brake pedal; and a control unit (30) configured to apply different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit (10) and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) at a plurality of stages defined while the brake pedal is pressed and released, and which determines a required brake pressure P necessary to brake the vehicle, wherein the plurality of stages includes a first stage where the pedal travel is equal to or shorter than a preset reference pedal travel STR_A and wherein the plurality of stages further includes a second stage where the pedal travel is longer than the reference pedal travel STR_A characterized by that in the second stage the control unit (30) determines the required brake pressure P taking into account the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as a pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX.

Description

CROSS-REFERENCES TO RELATED REGISTRATIONS BACKGROUND OF THE INVENTION

[0001] The present invention relates to a brake control device and method for a vehicle and in particular to a brake control device and method for a vehicle with which the required brake pressure necessary for braking a vehicle can be determined.

[0002] Recently, environmentally friendly vehicles, such as EVs (Electric Vehicles), PHEVs (Plug-in Hybrid Electric Vehicles) and HEVs (Hybrid Electric Vehicles), have become increasingly popular, and research is continuously being conducted on a regenerative braking system that can be used in environmentally friendly vehicles.

[0003] In such an environmentally friendly vehicle, the required brake pressure needed to brake the vehicle (that is, the hydraulic brake pressure generated by a master cylinder and applied to a wheel cylinder) is determined by means of a brake pedal travel sensed by a pedal travel sensor, and controls a brake ECU (Electronic Control Unit) used in the vehicle, an actuator, such as an electric amplifier (motor), to generate the required brake pressure through the master cylinder, thereby braking the vehicle.

[0004] Furthermore, when a driver presses the brake pedal, the driver is given a pedal feel by a reaction force generated by a rubber damper or spring of a pedal simulator.

[0005] In the current state of the art, the required brake pressure is determined by a method that applies a pedal travel sensed by the pedal position sensor to predetermined characteristic map information. Therefore, the adjustment of pedal feel and the degree of design freedom are inevitably limited, and the force with which the driver presses the brake pedal cannot be taken into account when generating the required brake pressure.

[0006] The prior art is described in Korean patent application publication no. KR 10 2014 0 142 478 A, published on December 12, 2014. DE 10 2017 202 361 A1 discloses a brake control device with the features of the preamble of claim 1. Further brake control devices are known from DE 600 36 269 T2 and DE 10 2008 051 452 A1. OVERVIEW OF THE INVENTION

[0007] Embodiments of the present invention relate to a brake control device and method for a vehicle, which solve the problem encountered in the prior art that the adjustment of pedal feel and the degree of design freedom are limited, and that the force with which a driver applies the brake pedal is not taken into account when generating the required brake pressure, since the required brake pressure is determined based on the pedal travel. Starting from the prior art, the invention thus aims to solve the aforementioned problem of the prior art. This problem is achieved according to the invention with a brake control device according to claim 1 and a brake control method according to claim 8.

[0008] In one embodiment, a brake control device for a vehicle comprises: a pedal travel sensing unit configured to sensing a pedal travel of a brake pedal; a pedal simulator pressure sensing unit configured to sensing a pressure of a pedal simulator that provides a reaction force in response to the force applied to the brake pedal; and a control unit configured to apply different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit at a plurality of stages defined while the brake pedal is pressed and released, and which determines the required brake pressure P necessary to brake the vehicle.

[0009] According to the invention, the plurality of stages comprises a first stage in which the pedal travel is equal to or shorter than a preset reference pedal travel STR_A.

[0010] In the first stage, the control unit can determine the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit to the preset travel-pressure relationship information.

[0011] According to the invention, the plurality of stages further comprises a second stage in which the pedal travel is longer than the reference pedal travel STR_A. In the second stage, the control unit determines the required brake pressure P, taking into account the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX, as a pedal simulator pressure that corresponds to the maximum required brake pressure P_MAX.

[0012] In the second stage, the control unit can determine the required brake pressure P by means of a procedure for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit to a slope that is determined on the basis of the pedal simulator pressure P_SIM_A, which is determined by the pedal simulator sensing unit at the reference pedal travel STR_A, the required brake pressure P_A, which is determined at the reference pedal travel STR_A, the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX.

[0013] The multitude of stages can further include a third stage from a pedal travel STR_B sensed by the pedal travel sensing unit at the time when the required brake pressure, which is determined while the brake pedal is released in the second stage, reaches the required brake pressure P_A, to a reference pedal travel STR_C which is preset to a lower value than the reference pedal travel STR_A.

[0014] In the third stage, the control unit can determine the required brake pressure P by means of a procedure for applying the pedal travel STR sensed by the pedal travel sensing unit to a gradient that is determined on the basis of the pedal travel STR_B, the required brake pressure P_A, the reference pedal travel STR_C and the required brake pressure P_B, which is determined using the relationship information at the reference pedal travel STR_C.

[0015] The multitude of stages can further include a fourth stage, ranging from the pedal simulator pressure P_SIM_B sensed by the pedal travel sensing unit at the time when the brake pedal is pressed again while the brake pedal is released at the third stage, to the maximum pedal simulator pressure P_SIM_MAX.

[0016] In the fourth stage, the control unit can determine the required brake pressure P by means of a procedure for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit to a slope that is determined on the basis of the pedal simulator pressure P_SIM_B, the required brake pressure P_C, which is determined at the time when pressure is applied to the brake pedal again, the maximum pedal simulator pressure P_SIM_MAX and the maximum required brake pressure P_MAX.

[0017] In a further embodiment, a brake control method for a vehicle comprises: sensing, by means of a pedal travel sensing unit, a pedal travel of a brake pedal; sensing, by means of a pedal simulator pressure sensing unit, a pressure of a pedal simulator that provides a reaction force in response to a force applied when the brake pedal is depressed; and applying, by means of a control unit, different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit at a plurality of stages defined while the brake pedal is depressed and released, and determining the required brake pressure P necessary to brake the vehicle.The multiple stages include a first stage where the pedal travel is equal to or shorter than a preset reference pedal travel STR_A, and a second stage where the pedal travel is longer than the reference pedal travel STR_A. When determining the required brake pressure in the second stage, the control unit calculates the required brake pressure P, taking into account the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX, as a pedal simulator pressure that corresponds to the maximum required brake pressure P_MAX.

[0018] In the present embodiments, the required brake pressure can be determined using the brake control device and method by selectively utilizing the pedal travel and pedal simulator pressure, thereby adjusting the brake feel and ensuring a degree of design freedom. Furthermore, the brake control device and method can take into account an additional braking intention based on the force applied by the driver when pressing the brake pedal in generating the required brake pressure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram illustrating a brake control device for a vehicle according to an embodiment of the present invention. Fig. Figures 2 to 5 are diagrams describing a process in which the brake control device for a vehicle according to the embodiment of the present invention determines the required brake pressure at each stage. Fig. Figure 6 is a flowchart for describing a brake control procedure for a vehicle according to an embodiment of the present invention. DESCRIPTION OF SPECIFIC EXECUTION FORMS

[0019] A brake control device and method for a vehicle according to an embodiment of the present invention are described in more detail below with reference to the accompanying drawings. It should be noted that the drawings are not precisely to scale and may be exaggerated with regard to line thickness or the size of components; this is done solely for the sake of clarity and comprehensibility. Furthermore, the terms used here have been chosen with consideration for the functions of the invention and may be modified according to the custom or intention of the users or operators. Therefore, the definitions of the terms are to be understood in accordance with the entirety of the disclosures presented herein.

[0020] Fig. 1 is a block diagram illustrating a brake control device for a vehicle according to an embodiment of the present invention, and Fig. Figures 2 to 5 are diagrams describing a process in which the brake control device for a vehicle according to the embodiment of the present invention determines the required brake pressure at each stage.

[0021] According to Fig. 1 The brake control device for a vehicle according to the embodiment of the present invention can comprise a pedal travel sensing unit 10, a pedal simulator pressure sensing unit 20, a control unit 30 and a brake actuator 40.

[0022] The pedal travel sensing unit 10 can sense the pedal travel of a brake pedal generated when a driver presses the brake pedal and transmit the sensed pedal travel to the control unit 30, as described below. The pedal travel sensing unit 10 can be implemented as a pedal travel sensor that senses pedal travel by detecting a rotation angle of a pedal arm based on a zero point.

[0023] The pedal simulator pressure sensing unit 20 can sense the pressure of a pedal simulator, which provides a reaction force in response to a force applied by the driver when the brake pedal is depressed, and transmit the sensed pressure to the control unit 30. The pedal simulator pressure sensing unit 20 can be implemented as a pressure sensor located in a flow path between the pedal simulator and a reservoir (not shown) and can sense the pedal simulator pressure.

[0024] The control unit 30 can apply different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit 10 and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 at a variety of defined levels while the brake pedal is pressed and released. This determines the required brake pressure P needed to brake the vehicle (that is, the hydraulic brake pressure generated by a master cylinder and applied to a wheel cylinder). The control unit 30 can be implemented as a brake ECU (electronic control unit) for controlling the vehicle's braking.

[0025] First, the multitude of stages that are defined while the brake pedal is pressed and released will be discussed in relation to Fig. 2 comprehensively described.

[0026] In a first stage, where the pedal travel is equal to or shorter than a preset reference pedal travel STR_A, the pedal travel STR sensed by the pedal travel sensing unit 10 can be used to determine the required brake pressure P.

[0027] In a second stage, where the pedal travel is longer than the reference pedal travel STR_A, the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 can be used to determine the required brake pressure P.

[0028] In a third stage, which corresponds to a process in which the second stage switches to the first stage when the brake pedal is released, the pedal travel STR sensed by the pedal travel sensing unit 10 can be used to determine the required brake pressure P.

[0029] In a fourth stage, where the brake pedal is pressed again while being released in the third stage, the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 can be used to determine the required brake pressure P.

[0030] Based on the preceding comprehensive descriptions of the first through fourth stages, a process for calculating the required brake pressure at each stage is described, with the first through fourth stages being specifically defined. It should be noted that below, expressions are uniquely identified by reference symbols. For reference purposes, the horizontal axes of the Fig. 2 and Fig. The diagrams shown in 4 indicate the pedal travel such that, in the first and third stages, the pedal travel STR sensed by the pedal travel sensor unit 10 is used to determine the required brake pressure P, and the horizontal axes of the diagrams shown in Fig. 3 and Fig. The diagrams shown in Figure 5 indicate the pedal simulator pressure in such a way that, in the second and fourth stages, the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 is used to determine the required brake pressure P.

[0031] First, the process for calculating the required brake pressure at the first stage is described.

[0032] In the first stage, where the pedal travel is equal to or shorter than the preset reference pedal travel STR_A, the pedal travel STR sensed by the pedal travel sensing unit 10 can be used to determine the required brake pressure P.

[0033] The reference pedal travel STR_A, which serves as a reference value to distinguish between the first and second stages, can be selected in various ways according to the designer's intent and preset in control unit 30. For example, a driver may intend to brake based on a reaction force provided by the pedal simulator when the amount of pressure applied to the brake pedal is increased. Therefore, if the pedal travel exceeds a predetermined value, a parameter used to generate the required brake pressure can be converted from the pedal travel to a pedal simulator pressure to indicate the driver's braking intent.Taking such an aspect into account, the predetermined value can be selected based on the intention of a designer and a test result and set in advance as the reference pedal travel STR_A in the control unit 30.

[0034] Therefore, in the first stage, the control unit 30 can determine the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit 10 with preset “travel-pressure relationship information”. Fig. Figure 2 shows the “displacement-pressure relationship information” as a diagram showing the required brake pressure as a function of the pedal travel, and the “displacement-pressure relationship information” can be preset in various ways (a characteristic map, a lookup table or a function of the required brake pressure for the pedal travel) based on test results of the designer.

[0035] As described below, the brake control device can enter the first stage after the pedal travel STR, sensed by the pedal travel sensing unit 10, reaches a preset reference pedal travel STR_C at the third stage, when the brake pedal is released. Thus, the control unit 30 can determine the required brake pressure P by applying the pedal travel STR, sensed by the pedal travel sensing unit 10, to the "travel-pressure relationship information" as described above.

[0036] Next, a process for calculating the required brake pressure at the second stage is described.

[0037] In the second stage, where the pedal travel is longer than the reference pedal travel STR_A, the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 can be used to determine the required brake pressure P.

[0038] According to Fig. 3 In the second stage, the control unit 30 can determine the required brake pressure P by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 to a slope, which is determined on the basis of the pedal simulator pressure P_SIM_A, which is sensed by the pedal simulator pressure sensing unit 20 at the reference pedal travel STR_A, the required brake pressure P_A, which is determined at the reference pedal travel STR_A, the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX.

[0039] The pedal simulator pressure P_SIM_A can display the pedal simulator pressure sensed by the pedal simulator pressure sensing unit 20 at the moment the pedal travel reaches the reference pedal travel STR_A. The required brake pressure P_A, sensed at the reference pedal travel STR_A, can display the required brake pressure determined by applying the reference pedal travel STR_A in the "Travel-Pressure Relationship Information". The maximum required brake pressure P_MAX can display the maximum required brake pressure that can be generated by the master cylinder. The maximum pedal simulator pressure P_SIM_MAX can display the pedal simulator pressure at which the maximum required brake pressure P_MAX is generated.

[0040] According to Fig. 3. Therefore, the required brake pressure P at the second stage can be determined according to equation 1 below. P=P_A+P_MAX−P_AP_SIM_MAX−P_SIM_A(P_SIM−P_SIM_A)

[0041] Next, a process for calculating the required brake pressure at the third stage is described.

[0042] In the third stage, which indicates a step from a pedal travel STR_B sensed by the pedal travel sensing unit 10 at the time at which the required brake pressure P, determined while the brake pedal is released in the second stage, reaches the required brake pressure P_A, to a reference pedal travel STR_C that is preset to be shorter than the reference pedal travel STR_A, the pedal travel STR sensed by the pedal travel sensing unit 10 can be used to determine the required brake pressure P.

[0043] To describe the process for calculating the required brake pressure at the third stage, the hysteresis that occurs at the second stage is first described.

[0044] When the brake pedal is released, the pedal simulator pressure can be lower than when the brake pedal is depressed, even though the same pedal travel is generated. Therefore, when the required brake pressure is determined according to Equation 1 in the second stage, hysteresis can occur between the case where the brake pedal is depressed and the case where it is released, as shown in Fig. Figure 3 illustrates this. Therefore, in the second stage, the required brake pressure can be determined to be lower when the brake pedal is released than when it is depressed. This means that when the brake pedal is released, the pedal travel sensed by the pedal travel sensor unit 10 may be longer than when the brake pedal is depressed, even though the required brake pressure reaches the same level. Therefore, when determining the required brake pressure in the third stage (the stage following the release of the brake pedal in the second stage), the hysteresis occurring in the second stage must be taken into account.

[0045] The process for determining the required brake pressure, taking into account the hysteresis occurring in the second stage, is described with reference to Fig. 4 described in more detail. In the third stage, the control unit 30 can determine the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit 10 to a gradient, which is determined on the basis of the pedal travel STR_B, the required brake pressure P_A, the reference pedal travel STR_C and the required brake pressure P_B, which is determined by means of the “travel-pressure relationship information” at the reference pedal travel STR_C.

[0046] According to Fig. 4. Therefore, the required brake pressure P at the third stage can be determined according to equation 2 below. P=P_B+P_A−P_BSTR_B−STR_C(STR−STR_C)

[0047] If the required brake pressure is determined at the third stage according to equation 2, the required brake pressure that maintains a continuous path with the required brake pressure when the brake pedal is released at the second stage can be determined at the third stage, even though hysteresis occurs at the second stage.

[0048] The reference pedal travel STR_C can be preset in control unit 30 as a value lower than the reference pedal travel STR_A, and the value can be selected in various ways based on the designer's intent and test results.

[0049] Next, a process for calculating the required brake pressure at the fourth stage is described.

[0050] In the fourth stage, which represents a step from a pedal simulator pressure P_SIM_B sensed by the pedal simulator pressure sensing unit 20 at the time when the brake pedal is pressed again while the brake pedal is released in the third stage, to the maximum pedal simulator pressure P_SIM_MAX, the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 can be used to determine the required brake pressure P.

[0051] Since the pedal simulator pressure P_SIM_B has a different value than the pedal simulator pressure P_SIM_A described in the preceding process, the slope must be reset, as the slope calculated in the second stage cannot be used.

[0052] According to Fig. 5 For this process, the control unit 30 can determine the required brake pressure P at the fourth stage by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 to a gradient that is determined on the basis of the pedal simulator pressure P_SIM_B, the required brake pressure P_C, which is determined at the time when the brake pedal is pressed again, the maximum pedal simulator pressure P_SIM_MAX and the maximum required brake pressure P_MAX.

[0053] According to Fig. 5. Therefore, the required brake pressure P at the fourth stage can be determined according to equation 3 below. P=P_C+P_MAX−P_CP_SIM_MAX−P_SIM_B(P_SIM−P_SIM_B)

[0054] When the required brake pressures are determined at each of the first to fourth stages, the control unit 30 can control the brake actuator 40, such as an electric amplifier (motor), to generate the required brake pressure through the master cylinder, thereby braking the vehicle.

[0055] As can be seen in the process described above, the brake control device according to the present embodiment can determine the required brake pressure by using the pedal travel when the brake pedal is pressed and released in a region where the amount of pedal travel is relatively small, and determine the required brake pressure by using the pedal simulator pressure when the brake pedal is pressed and released in a region where the amount of pedal travel is relatively large, thus taking into account the driver's braking intention when generating the required brake pressure. Furthermore, the brake control device can define the plurality of stages during the depress and release of the brake pedal and determine the required brake pressure at each stage using different calculation methods, thereby fine-tuning the brake feel and ensuring a degree of design freedom.

[0056] Fig. Figure 6 is a flowchart for describing a brake control procedure for a vehicle according to an embodiment of the present invention.

[0057] Based on Fig. Section 6 describes the brake control method for a vehicle according to the embodiment of the present invention. First, in step S10, the pedal travel sensing unit 10 can determine the pedal travel of the brake pedal, and in step S20, the pedal simulator pressure sensing unit 20 can sense the pressure of the pedal simulator, which provides a reaction force in response to a force applied when the brake pedal is pressed.

[0058] Steps S10 and S20 are parallel steps that are performed by means of independent operations of the pedal travel sensing unit 10 and the pedal simulator pressure sensing unit 20, and the temporal sequence of the operations is not restricted to a specific order.

[0059] The control unit 30 can apply different calculation methods by selectively using the pedal travel STR sensed by the pedal travel sensing unit 10 and the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit 20 at a variety of stages defined while the brake pedal is pressed and released, thereby determining at step S30 the required brake pressure P needed to brake the vehicle.

[0060] The multitude of stages may include a first stage where the pedal travel is equal to or shorter than the preset reference pedal travel STR_A.

[0061] In the first stage of step S30, the control unit 30 can determine the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit 10 to the preset “travel-pressure relationship information”.

[0062] The multitude of stages can also include a second stage where the pedal travel is longer than the reference pedal travel STR_A.

[0063] In the second stage of step S30, the control unit 30 can determine the required brake pressure P by applying the pedal simulator pressure P_SIM, sensed by the pedal simulator pressure sensing unit 20, to a slope determined based on the pedal simulator pressure P_SIM_A, determined by the pedal simulator pressure sensing unit 20 at the reference pedal travel STR_A, the required brake pressure P_A determined at the reference pedal travel STR_A, the preset maximum required brake pressure P_MAX, and the maximum pedal simulator pressure P_SIM_MAX, which is the pedal simulator pressure corresponding to the maximum required brake pressure P_MAX. Since the process for determining the required brake pressure has been described above according to Equation 1, its detailed description is omitted here.

[0064] The multitude of stages can further include a third stage from a pedal travel STR_B sensed by the pedal travel sensing unit 10 at the time when the required brake pressure, which is determined while the brake pedal is released in the second stage, reaches the required brake pressure P_A, to a reference pedal travel STR_C which is set to a lower value than the reference pedal travel STR_A.

[0065] In the third stage of step S30, the control unit 30 can determine the required brake pressure P by applying the pedal travel STR, sensed by the pedal travel sensing unit 10, to a slope determined based on the pedal travel STR_B, the required brake pressure P_A, the reference pedal travel STR_C, and the required brake pressure P_B, which is determined using the "travel-pressure relationship information" at the reference pedal travel STR_C. Since the process for determining the required brake pressure has been described above according to Equation 2, its detailed description is omitted here.

[0066] The multitude of stages can further include a fourth stage from the pedal simulator pressure P_SIM_B sensed by the pedal travel pressure sensing unit 20 at the time when the brake pedal is pressed again while the brake pedal is released at the third stage, to the maximum pedal simulator pressure P_SIM_MAX.

[0067] In the fourth stage of step S30, the control unit 30 can determine the required brake pressure P by applying the pedal simulator pressure P_SIM, sensed by the pedal simulator pressure sensing unit 20, to a slope determined based on the pedal simulator pressure P_SIM_B, the required brake pressure P_C, which is determined at the time when the brake pedal is pressed again, the maximum pedal simulator pressure P_SIM_MAX, and the maximum required brake pressure P_MAX. Since the process for determining the required brake pressure has been described above according to Equation 3, its detailed description is omitted here.

[0068] When the required brake pressures are determined at each of the first to fourth stages, the control unit 30 can control the brake actuator 40, such as an electric amplifier (motor), to generate the required brake pressure through the master cylinder, thereby braking the vehicle.

[0069] With the brake control method according to the embodiment of the present invention, the required brake pressure can be determined by using the pedal travel and the pedal simulator pressure, thereby adjusting the brake feel and ensuring a degree of design freedom. Furthermore, the brake control method can take into account an additional braking intention based on the force applied by the driver when pressing the brake pedal in generating the required brake pressure.

[0070] Although preferred embodiments of the invention have been described for illustrative purposes, it will be apparent to those skilled in the art that numerous modifications, additions and substitutions are possible without deviating from the scope and content of the invention as defined in the attached claims.

Claims

[1] Brake control device for a vehicle, comprising: a pedal travel sensing unit (10) designed to sens the pedal travel of a brake pedal; a pedal simulator pressure sensing unit (20) configured to sensing a pressure from a pedal simulator that provides a reaction force in response to the force applied to the brake pedal; and a control unit (30) configured to apply different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit (10) and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) at a plurality of stages defined while the brake pedal is pressed and released, and which determines a required brake pressure P necessary to brake the vehicle, wherein the plurality of stages includes a first stage where the pedal travel is equal to or shorter than a preset reference pedal travel STR_A and wherein the plurality of stages further includes a second stage where the pedal travel is longer than the reference pedal travel STR_A characterized by , that in the second stage the control unit (30) determines the required brake pressure P taking into account the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as a pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX. [2] Brake control device according to claim 1 in which, in the first stage, the control unit (30) determines the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit (10) with preset travel-pressure relationship information. [3] Brake control device according to claim 1, wherein in the second stage the control unit (30) determines the required brake pressure P by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) to a gradient determined on the basis of the pedal simulator pressure P_SIM_A determined by the pedal simulator pressure sensing unit (20) at the reference pedal travel STR_A, the required brake pressure P_A determined at the reference pedal travel STR_A, the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX. [4] Brake control device according to claim 3, wherein the plurality of stages further comprises a third stage from a pedal travel STR_B sensed by the pedal travel sensing unit (10) at the time when the required brake pressure, which is determined while the brake pedal is released in the second stage, reaches the required brake pressure P_A, to a reference pedal travel STR_C which is set to a lower value than that of the reference pedal travel STR_A. [5] Brake control device according to claim 4, wherein in the third stage the control unit (30) determines the required brake pressure P by means of a method for applying the pedal travel STR sensed by the pedal travel sensing unit (10) to a gradient which is determined on the basis of the pedal travel STR_B, the required brake pressure P_A, the reference pedal travel STR_C and the required brake pressure P_B which is determined by means of the relationship information at the reference pedal travel STR_C. [6] Brake control device according to claim 5, wherein the plurality of stages further comprises a fourth stage from the pedal simulator pressure P_SIM_B sensed by the pedal travel pressure sensing unit (20) at the time when the brake pedal is pressed again while the brake pedal is released at the third stage, to the maximum pedal simulator pressure P_SIM_MAX. [7] Brake control device according to claim 6, wherein at the fourth stage the control unit (30) determines the required brake pressure P by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) to a gradient which is determined on the basis of the pedal simulator pressure P_SIM_B, the required brake pressure P_C which is determined at the time when the brake pedal is pressed again, the maximum pedal simulator pressure P_SIM_MAX and the maximum required brake pressure P_MAX. [8] Brake control procedure for a vehicle comprising: Sensing, by means of a pedal travel sensing unit (10), of a pedal travel of a brake pedal; Sensing, by means of a pedal simulator pressure sensing unit (20), of a pressure of a pedal simulator which provides a reaction force in response to a force when pressing on the brake pedal; and Applying, by means of a control unit (30), different calculation methods by selectively using a pedal travel STR sensed by the pedal travel sensing unit (10) and a pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) at a plurality of stages defined while the brake pedal is pressed and released, and determining the required brake pressure P necessary to brake the vehicle, wherein the plurality of steps includes a first step where the pedal travel is equal to or shorter than a preset reference pedal travel STR_A and wherein the plurality of steps further includes a second step where the pedal travel is longer than the reference pedal travel STR_A characterized by , that when determining the required brake pressure at the second stage, the control unit (30) determines the required brake pressure P taking into account the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as a pedal simulator pressure that corresponds to the maximum required brake pressure P_MAX [9] Brake control method according to claim 8, wherein, when determining the required brake pressure at the first stage, the control unit (30) determines the required brake pressure P by applying the pedal travel STR sensed by the pedal travel sensing unit (10) at the preset travel-pressure relationship information. [10] Brake control method according to claim 8, wherein, when determining the required brake pressure at the second stage, the control unit (30) determines the required brake pressure P by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) to a slope which is determined on the basis of the pedal simulator pressure P_SIM_A, which is determined by the pedal simulator pressure sensing unit (20) at the reference pedal travel STR_A, the required brake pressure P_A, which is determined at the reference pedal travel STR_A, the preset maximum required brake pressure P_MAX and the maximum pedal simulator pressure P_SIM_MAX as pedal simulator pressure which corresponds to the maximum required brake pressure P_MAX. [11] Brake control method according to claim 10, wherein the plurality of stages further comprises a third stage from a pedal travel STR_B sensed by the pedal travel sensing unit (10) at the time when the required brake pressure, which is determined while the brake pedal is released in the second stage, reaches the required brake pressure P_A, to a reference pedal travel STR_C which is set to a lower value than that of the reference pedal travel STR_A. [12] Brake control method according to claim 11, wherein when determining the required brake pressure at the third stage the control unit (30) determines the required brake pressure P by means of a method for applying the pedal travel STR sensed by the pedal travel sensing unit (10) to a slope which is determined on the basis of the pedal travel STR_B, the required brake pressure P_A, the reference pedal travel STR_C and the required brake pressure P_B which is determined by means of the relationship information at the reference pedal travel STR_C. [13] Brake control method according to claim 12, wherein the plurality of stages further comprises a fourth stage from the pedal simulator pressure P_SIM_B sensed by the pedal travel pressure sensing unit (20) at the time when the brake pedal is pressed again while the brake pedal is released at the third stage, to the maximum pedal simulator pressure P_SIM_MAX. [14] Brake control method according to claim 13, wherein, when determining the required brake pressure at the fourth stage, the control unit (30) determines the required brake pressure P by means of a method for applying the pedal simulator pressure P_SIM sensed by the pedal simulator pressure sensing unit (20) to a slope determined on the basis of the pedal simulator pressure P_SIM_B, the required brake pressure P_C determined at the time when the brake pedal is pressed again, the maximum pedal simulator pressure P_SIM_MAX and the maximum required brake pressure P_MAX.

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