BRAKE CONTROL DEVICE

Abstract

Enabling stable braking regardless of influences from aging or similar factors of a braking device. A brake ECU 30 is provided for a vehicle 1 with a brake device 11, which can adjust a braking force depending on the supplied hydraulic pressure, wherein the vehicle 1 comprises: a main pressure sensor 17 configured to measure the hydraulic pressure supplied to the brake device 11; and a G-sensor 44 and a wheel speed sensor 12 configured to detect acceleration of the vehicle 1 and to measure acceleration information, wherein the brake ECU 30 is configured to include: a pressure command value calculation section 36 configured to determine a hydraulic pressure to be supplied to the brake device 11 at a time of deceleration of the vehicle 1 based on a preset coefficient and to cause the determined hydraulic pressure to be supplied to the brake device 11;and a calculation section 31 for the brake torque coefficient, which is configured to learn a coefficient candidate that is a candidate for changing the coefficient, and to change the coefficient based on a relationship between the hydraulic pressure and the acceleration in the coefficient candidate.

Description

Technical field

[0001] The present invention relates to a brake control device for controlling the brake of a vehicle. State of the art

[0002] Traditionally, a braking control device was used that automatically brakes a vehicle to prevent a collision. A braking control device designed to prevent such a collision is focused on emergency braking, and therefore the sensation conveyed to a vehicle occupant during braking is not particularly significant.

[0003] In recent years, a brake control device has been used for situations where a vehicle is automatically parked or when following a vehicle in front in a traffic jam. In such cases, whether the vehicle is parked or following a vehicle in front in a traffic jam, an occupant of the vehicle becomes sensitive to the vehicle's behavior during braking due to the relatively low speed. Therefore, in such cases, it has been required that an occupant not experience a sensation of sudden braking (indicating excessively hard braking), a sensation of insufficient deceleration (indicating inadequate deceleration), a sensation of erratic braking (indicating a drastic change in vehicle speed), and the like.

[0004] A brake control device generally performs a regulation to control the target speed or the target stopping distance.

[0005] For example, a technology relating to the braking of a vehicle at the time of parking assistance is known, a technology which can eliminate a driver’s feeling of discomfort in relation to the speed of the vehicle at the time of parking assistance or the strain of braking in order to eliminate discomfort (see PTL 1).

[0006] Furthermore, a technology for reducing a vehicle's shock by controlling the pressure applied to a brake when the vehicle comes to a stop is known (see PTL 2). List of patent literature PTL 1: JP 2013-82376 A PTL 2: JP 2007-55355 A

[0007] DE 10 2015 224 601 A1 describes a brake control system in which a target brake pressure can be adjusted if the deceleration characteristic is missing.

[0008] JP 2007 283 882 A describes a device for determining road inclination. This device evaluates the relationship between braking force and the resulting deceleration. TECHNICAL PROBLEM

[0009] For example, a braking device that slows a vehicle uses a friction element, such as a brake pad or brake shoe. The coefficient of friction of this element varies with operating conditions, aging, and other factors. Therefore, the braking torque generated by the braking device will vary, even if the same hydraulic pressure is applied to the device to perform the braking action.

[0010] Accordingly, if hydraulic pressure is fed into the brake device from the brake control unit with the same control, the behavior at the time of braking differs completely from the initial behavior at the time of braking (ideally corresponding to the design behavior at the time of braking), depending on the state of the brake device (basically the state of the friction element), and there is a possibility that the occupant will experience a feeling of discomfort.

[0011] Furthermore, in the case of automatic parking or similar systems where a braking distance with an accuracy in units of several centimeters is to be ensured, when hydraulic pressure is applied to a braking device by a brake control device, there is a possibility that the accuracy of the braking distance cannot be sufficiently guaranteed depending on the conditions, e.g., of the friction element. Summary of the invention

[0012] The object of the present invention is to provide a brake control device that can achieve stable braking independently of influences due to aging or the like of a brake device. Solution to the problem

[0013] The above problem is solved by the features of claim 1. A brake control device has the features of claim 1. A brake control device for a vehicle with a brake device that can adjust a braking force depending on the supplied hydraulic pressure comprises: a hydraulic pressure sensor configured to measure the hydraulic pressure supplied to the brake device; and an acceleration information sensor configured to detect acceleration of the vehicle and measure acceleration information, wherein the brake control device comprises: a hydraulic pressure supply control section configured to determine a hydraulic pressure supplied to the brake device at a time of deceleration of the vehicle based on a preset coefficient and to cause the determined hydraulic pressure to be supplied to the brake device;and a coefficient change section configured to learn a coefficient candidate that is a candidate for changing the coefficient, and to change the coefficient based on a relationship between the hydraulic pressure and the acceleration in the coefficient candidate. Claim 1 further specifies features. Advantageous effects of the invention

[0014] According to the present invention, it is possible to achieve stable braking regardless of influences caused by aging or the like of a braking device. Brief description of the drawings Fig. Figure 1 is an overall configuration diagram of a vehicle according to one embodiment. Fig. Figure 2 is a configuration diagram of a brake ECU and a functional section relating to the brake ECU according to an embodiment. Fig. Figure 3 is a graph illustrating the detection of a braking torque coefficient according to one embodiment. Fig. Figure 4 is a diagram illustrating the brake control according to one embodiment. Fig. Figure 5 is a flowchart of a learning change processing of the braking torque coefficient according to one embodiment. Description of embodiments

[0015] One embodiment is described with reference to the drawings. It should be noted that the embodiment described below does not limit the invention according to the claims, and elements and all combinations thereof described in the embodiment are not necessarily essential for the solution of the invention.

[0016] Fig. Figure 1 is an overall configuration diagram of a vehicle according to one embodiment.

[0017] A vehicle 1 containing a brake control device comprises several (in Fig. 1 four) wheels 10, a brake device 11 provided for each wheel 10, a wheel speed sensor 12, which is an example of an acceleration information sensor, a master cylinder 13, an electrically controlled amplifier (electronic control amplifier) ​​unit 14, an ABS (anti-lock braking system) / ESC (electronic stability control) unit 15, a pipe 16, a main pressure sensor 17, which is an example of a hydraulic pressure sensor, a CAN (control area network) 18, a power steering unit 19, an engine ECU (electronic control unit) 20, a brake ECU (electronic control unit) 30, which is an example of a brake control device, a transmission unit 40, a camera 42, a sonar 43, an acceleration sensor (G-sensor) 44, which is an example of an acceleration information sensor, and a yaw rate sensor 45.

[0018] The steering support unit 19, the sonar 43, the electrically controlled amplification unit 14, the ABS / ESC unit 15, the engine ECU 20, the brake ECU 30 and the transmission unit 40 are interconnected via the CAN 18 in such a way that detection values ​​from various sensors, which are detected by any unit or the like, can be received by another unit or the like.

[0019] The main cylinder 13 and the brake device 11 are connected via the pipe 16.

[0020] The brake device 11, for example, is a disc brake device that includes a brake rotor, which rotates as one unit with the wheel 10, and a brake pad, which is a friction element, to generate a braking force that slows the rotation of the wheel 10. The braking force generated when the brake pad clamps the brake rotor is adjusted by the pressure (hydraulic pressure) of a brake fluid supplied to the brake device 11.

[0021] The wheel speed sensor 12 outputs a pulse waveform based on indentations and protrusions on a sensor rotor that rotates as one unit with the wheel 10 to the ABS / ESC unit 15.

[0022] The main pressure sensor 17 detects the pressure (main pressure) of the brake fluid supplied to the master cylinder 13 and outputs it to the electrically controlled amplifier unit 14.

[0023] For example, camera 42 is positioned to face the front and rear of vehicle 1 and captures an image (or video) of the front and rear compartments of vehicle 1. Camera 42 outputs the captured image (or video) to the brake ECU 30.

[0024] The sonar 43 is arranged around the vehicle 1, generates an ultrasonic wave to the circumference of the vehicle 1 and indicates the distance to an obstacle around the vehicle 1 based on the reflection conditions of the ultrasonic wave.

[0025] The G-sensor 44 detects the front and rear acceleration of the vehicle 1 and transmits it to the ABS / ESC unit 15. The yaw rate sensor 45 detects the angular velocity (yaw rate) around the vertical axis of the vehicle 1 and transmits it to the ABS / ESC unit 15.

[0026] The master cylinder 13 adjusts the pressure of the brake fluid in response to the pressing of a brake pedal, which is not shown, by the driver of the vehicle 1 or the operation of the electrically controlled booster unit 14 and supplies it to the brake device 11 via the pipe 16.

[0027] The electrically controlled amplifier unit 14 controls the adjustment of the hydraulic pressure by the main cylinder 13.

[0028] The ABS / ESC unit 15 is connected, for example, to the wheel speed sensor 12, the G-sensor 44, and the yaw rate sensor 45, and receives detection values ​​(detection signals) from the wheel speed sensor 12, the G-sensor 44, and the yaw rate sensor 45. The ABS / ESC unit 15 can independently control the supply of brake fluid between the master cylinder 13 and the brake devices 11. In particular, based on a signal from the wheel speed sensor 12 of each wheel 10, the ABS / ESC unit 15 controls the hydraulic pressure of the brake fluid supplied to the brake device 11 by the master cylinder 13, so that the wheel 10 does not lock up. In particular, the ABS / ESC unit 15, based on a signal from the wheel speed sensor 12 of each wheel 10, controls a detection value of the yaw rate sensor 45 and controls the hydraulic pressure of the brake fluid supplied to the brake device 45 by the master cylinder 13, so that the wheel 1 does not slip.

[0029] The steering support unit 19 assists the steering of the vehicle 1. For example, the steering support unit 19 controls the steering in such a way that the vehicle 1 moves into a predetermined parking position at the time of the automatic parking control for the vehicle 1, i.e., at the time of the control in which the vehicle 1 automatically moves into a predetermined parking position and is stopped.

[0030] The motor ECU 20 controls the operation of the motor based on various sensor values ​​transmitted via CAN 18 or the like.

[0031] The brake ECU 30 detects the distance to an obstacle or similar object (vehicle, stationary obstacle, moving body, or the like) around the vehicle 1, based on the image (or video) from camera 42. Furthermore, based on the distance to the surrounding obstacle or similar object detected by sonar 43, the brake ECU 30 specifies the presence or position of each obstacle or similar object around the vehicle 1. Additionally, the brake ECU 30 performs processing related to the brake control of the vehicle 1. Note that this processing related to brake control will be described later.

[0032] The transmission unit 40 changes the speed of the power output from the motor based on various sensor values ​​transmitted via CAN 18 or the like.

[0033] Next, the brake ECU and the functional section relating to the brake ECU will be described in detail.

[0034] Fig. Figure 2 is a configuration diagram of a brake ECU and a functional section relating to the brake ECU according to an embodiment.

[0035] The brake ECU 30 includes a calculation section 32 for target speed / target distance, a calculation section 33 for vehicle body acceleration, a calculation section 34 for estimated acceleration, a calculation section 35 for estimated speed, a pressure command value calculation section 36, which is an example of a hydraulic pressure supply control section, an initial value storage section 37, and a calculation section 31 for the brake torque coefficient, which is an example of a coefficient change section.The calculation section 31 for the brake torque coefficient, the calculation section 32 for target speed / target distance, the calculation section 33 for vehicle body acceleration, the calculation section 34 for estimated acceleration, the calculation section 35 for estimated speed, and the pressure command value calculation section 36 are configured when, for example, a processor (not shown) executes a program in the brake ECU 30. The initial value memory section 37 contains a memory (not shown) in the brake ECU 30.

[0036] The calculation section 32 for target speed / target distance determines a speed profile based on the image (or video) input from camera 42 and the distance to the surrounding obstacle or the like from the sonar 43. This speed profile includes a target speed and a target distance relative to a predetermined stopping position (e.g., parking position in the case of automatic parking control). It should be noted that the predetermined parking position can be determined based on the image or by an instruction from the driver displayed on the image.

[0037] Calculation section 33 for vehicle body acceleration calculates the front and rear acceleration of vehicle 1 (vehicle body acceleration: first acceleration) based on the detection signal from the G-sensor 44. Calculation section 34 for estimated acceleration calculates (estimates) the front and rear acceleration of vehicle 1 (estimated acceleration: second acceleration) based on a pulse signal from the wheel speed sensor 12. Calculation section 35 for estimated speed calculates (estimates) the speed (estimated speed) of vehicle 1 based on a pulse signal from the wheel speed sensor 12.

[0038] The braking torque coefficient calculation section 31 outputs a braking torque coefficient to the pressure command value calculation section 36 based on the target speed and target distance and the vehicle body acceleration or the estimated acceleration.

[0039] The braking torque coefficient is described here.

[0040] The following shows a view illustrating a braking torque coefficient according to one embodiment. Fig. Figure 3 is a graph illustrating the detection of a braking torque coefficient according to one embodiment. Ma=Ff+Fr Ff+Fr=2(2⋅μf⋅Af⋅RrotfRtiref⋅P+2⋅μf⋅Af⋅RrotrRtiref⋅P) (2) =2(Bf+Br)P (3) P=M2(Bf+Br)a TT=M2(Bf+Br) M VEHICLE MASS F BRAKING FORCE FRONT AND REAR ACCELERATION R tire TIRE MOTION RADIUS P rot EFFECTIVE RADIUS OF THE ROTOR B BRAKING TORQUE COEFFICIENT PER WHEEL µ COEFFICIENT (coating friction coefficient) A CROSS-SECTIONAL AREA OF THE BRAKE PISTON P MAIN PRESSURE T BRAKING TORQUE COEFFICIENT

[0041] When vehicle 1 is braked, the relationship given in formula (1) above is derived from Newton's equation of motion. Here, the subscript f denotes the front and r the back in the formulas above.

[0042] Furthermore, the braking force Ff + Fr of vehicle 1 is the sum of the braking forces of the brake devices 11 provided at the wheels 10 and is therefore expressed as given in formula (2). If, in formula (2), a coefficient relating to the braking forces of the wheels is expressed in terms of the main pressure P (referred to as the braking torque coefficient per wheel) by B, it is obtained as given in formula (3).

[0043] Here, according to the relationships of formula (1) and formula (3), the principal pressure P is expressed as given in formula (4).

[0044] Formula (4) states that the main pressure P is proportional to the front and rear acceleration a of vehicle 1. The proportionality coefficient of the main pressure P and the front and rear acceleration a of vehicle 1 in formula (4) is called the braking torque coefficient T, as given in formula (5).

[0045] As described above, the braking torque coefficient T can be calculated from the main pressure P and the front and rear accelerations a, since the main pressure P is proportional to the front and rear accelerations a of vehicle 1. In particular, as in Fig. Figure 3 shows where the horizontal axis is the front and rear acceleration a and the vertical axis is the main pressure P, and the braking torque coefficient T is a gradient of a graph.

[0046] The braking torque coefficient T varies with the friction coefficient µ of the brake pad. Therefore, a value that differs from the initial value (design value) in a state where the brake pad is not worn is calculated depending on the operating condition of the brake pad, taking into account aging changes and the like.

[0047] With renewed reference to Fig. 2. In calculation section 31, a candidate brake torque coefficient (brake torque coefficient candidate) is calculated for the braking torque coefficient at the time of braking based on at least one of the vehicle body acceleration or the estimated acceleration and the main pressure. In the present embodiment, the brake torque coefficient candidate is calculated based on at least one of the vehicle body acceleration or the estimated acceleration and the main pressure at the time of braking in a case where a predetermined driving condition (calculation condition) is met.

[0048] The predetermined driving condition can be at least one or more of the following conditions 1 to 4.

[0049] Condition 1: The speed of vehicle 1 is a predetermined value or less.

[0050] Condition 2: The acceleration of vehicle 1 (vehicle body acceleration, estimated acceleration) is a predetermined value or less.

[0051] Condition 3: The main pressure is a predetermined value or less.

[0052] Condition 4: The difference between the vehicle body acceleration and the estimated acceleration is a predetermined value or less.

[0053] In condition 1, the predetermined value can be an upper limit speed of a speed range assumed in the braking control of vehicle 1 (e.g., the upper limit speed of vehicle 1 at the time of automatic parking control (e.g., 10 km / h)). This makes it possible to correctly calculate a braking torque coefficient in the same driving condition as in the assumed speed range, and the use of this braking torque coefficient enables precise control of braking in the driving condition within the assumed speed range.

[0054] In condition 2, the predetermined value can be equal to or less than an upper limit of the acceleration of vehicle 1 at the time of automatic parking. In this way, at the time of automatic parking, brake control can be performed using the braking torque coefficient in the same driving condition, and the use of this drive torque coefficient enables precise control of braking in the assumed driving condition.

[0055] The predetermined value in condition 3 can be a value that is less than the pressure value at which the anti-lock brake is activated by the ABS / ESC unit 15. In this way, it is possible to calculate a drive torque coefficient while avoiding the state in which control of the anti-lock brake by the ABS / ESC unit 15 is performed, and braking can be precisely controlled in a state in which the anti-lock brake is not used.

[0056] According to condition 4, it is possible that a brake torque candidate will not be calculated, as in a case where the estimated acceleration is greater than the vehicle body acceleration, indicating that the vehicle 1 is traveling on a low-friction road surface, or where the vehicle body acceleration differs significantly from the estimated acceleration, indicating that the vehicle 1 is traveling on an inclined surface, if the acceleration (here the deceleration) of the vehicle 1 is influenced by something other than braking by the brake device 11 and a suitable brake torque coefficient cannot be calculated.

[0057] Furthermore, calculation section 31 for the brake torque coefficient determines whether the condition falls under a predetermined change condition, in which the brake torque coefficient is modified based on a multitude of brake torque coefficient candidates obtained at the time of different braking. If it is determined that the condition falls under the change condition, a new brake torque coefficient is calculated, and pressure command value calculation section 36 is notified accordingly, based on the multiple brake torque coefficient candidates. The change condition might, for example, be that the multitude of brake torque coefficient candidates falls within a range of relatively narrow values ​​with a predetermined probability or more (e.g.,seven or more out of ten) or that an average value of the multitude of candidates for the braking torque coefficient differs from the braking torque coefficient by a predetermined value or more at that time. Here, a new braking torque coefficient determined by calculation section 31 for the braking torque coefficient may be an average of braking torque coefficient candidates several times or may be any one of braking torque coefficient candidates several times.

[0058] The calculation section 31 for the brake torque coefficient notifies the pressure command value calculation section 36 of an initial value (setting value) of the brake torque coefficient stored in the initial value memory section 37, for example, when an initial setting instruction is accepted indicating that a brake pad of the brake device 11 has been changed. Thus, if the brake pad of the brake device 11 is changed, it is possible to restore the brake torque coefficient to a suitable initial value.

[0059] The pressure command value calculation section 36 calculates a command value (pressure command value) with respect to the main pressure of the master cylinder 13, which is set by the electrically controlled amplifier unit 14, on the basis of the brake torque coefficient, the estimated speed of the vehicle 1, which is estimated by the calculation section 35 for estimated speed, and the target speed, and outputs the pressure command value to the amplifier ECU 14B to control the supply of brake fluid to the brake device 11.For example, the pressure command value calculation section 36, using the braking torque coefficient, calculates a pressure command value (target main pressure) equal to the target deceleration calculated from the velocity profile previously determined by calculation section 35 for estimated velocity, and calculates a pressure command value setting to eliminate any difference between the estimated vehicle speed 1, estimated by calculation section 35 for estimated velocity, and the target velocity, and outputs an integral pressure command value. If the relationship between the front and rear acceleration and the main pressure force, which is in . Fig. As shown in Figure 3, which has been largely shifted and determined to require correction, the pressure command value calculation section 36 overwrites as the next pressure command value a value of the term (Bf + Br) of the braking torque coefficient in the formula (4) above into a value determined by the calculation section 31 for the braking torque coefficient, and formula (4) is used to calculate and output the pressure command value.

[0060] The initial value storage section 37 stores a braking torque coefficient (initial coefficient) in the case where the brake pad of the brake device 11 is in an initial state.

[0061] The electrically controlled amplifier unit 14 comprises an electrically controlled amplifier 14A and an amplifier ECU (electronic control unit) 14B. The electrically controlled amplifier 14A drives the master cylinder 13. The amplifier ECU 14B controls the electrically controlled amplifier 14A such that the main pressure through the master cylinder 13 is the pressure command value based on the main pressure detected by the main pressure sensor 17 and the pressure command value output by the pressure command value calculation section 36.

[0062] The ABS / ESC unit 15 comprises an ABS / ESC mechanism section 15A and an ABS / ESC ECU (electronic control unit) 15B. The ABS / ESC mechanism section 15A is a mechanism that can regulate the supply of brake fluid from the master cylinder 13 to the brake device 11. Based on detection values ​​from the wheel speed sensor 12, the G-sensor 44, and the yaw rate sensor 45, the ABS / ESC ECU 15B controls the supply of brake fluid (e.g., hydraulic pressure) from the master cylinder 13 to the brake device 11 via the ABS / ESC mechanism section 15A in such a way that the wheel 10 does not lock up. In particular, the ABS / ESC unit 15B, based on a signal from the wheel speed sensor 12 of each wheel 10, controls a detection value from the yaw rate sensor 45 or the like and controls the supply of brake fluid from the master cylinder 13 to each brake device 11 through the ABS / ECU mechanism section 15A, so that the vehicle does not slip.

[0063] Next, the brake control at the time of braking of vehicle 1 is described.

[0064] Fig. Figure 4 is a diagram illustrating the brake control according to one embodiment.

[0065] The calculation section 31 for the brake torque coefficient learns the brake torque coefficient using the main pressure, the front and rear G and the wheel speed as inputs in the learning change processing for the brake torque coefficient (see Fig. 5) and outputs a learned braking torque coefficient to the pressure command value calculation section 36.

[0066] The pressure command value calculation section 36 determines the pressure command value based on the braking torque coefficient, using the difference between the target vehicle speed and the estimated speed as input. The pressure command value calculation section 36 calculates a target deceleration to eliminate the difference between the target vehicle speed and the estimated speed and determines the pressure command value, which is a target value of the main pressure, using the calculated target deceleration and the braking torque coefficient. The pressure command value calculation section 35 transmits the determined pressure command value to the electrically controlled amplifier unit 14 to perform control such that the brake fluid is supplied to the brake device 11 at the corresponding hydraulic pressure.The electrically controlled amplifier unit 14 operates in such a way that the brake fluid of the main pressure is supplied to the brake device 11 from the master cylinder 13 according to the pressure command value.

[0067] As a result, the main pressure brake fluid is supplied to the brake devices 11 of the wheels 10, the vehicle 1 is braked by the brake devices 11 and the actual speed of the vehicle 1 is controlled so that it is the target speed.

[0068] In this case, the wheel speed sensor 12 outputs a pulse waveform corresponding to the speed of the wheel 10, and the estimation calculation section 35 calculates and outputs the estimated speed of the vehicle 1 based on the pulse waveform.

[0069] Next, the learning change processing for the braking torque coefficient is described in the braking torque coefficient calculation section 31.

[0070] Fig. Figure 5 is a flowchart of a learning change processing of the braking torque coefficient according to one embodiment.

[0071] The learning change processing for the braking torque coefficient is performed, for example, at the time of braking of vehicle 1.

[0072] The calculation section 31 for the braking torque coefficient determines whether a predetermined driving condition (calculation condition) is met (step S11), and if the calculation condition is not met (step S11: NO), which means that no suitable braking torque coefficient can be calculated, the processing returns to the top.

[0073] If the calculation condition is met (step S11: YES), the brake torque coefficient calculation section 31 calculates the candidate for the brake torque coefficient (step S12) based on at least one of the vehicle body acceleration or the estimated acceleration and main pressure.

[0074] Next, calculation section 31 for the braking torque coefficient determines whether the multitude of braking torque coefficient candidates calculated at the time of a multitude of braking operations satisfy the change condition (step S13).

[0075] Consequently, if the change condition is not met (step S13: NO), it is not necessary to change the current braking torque coefficient, and the processing returns to the top.

[0076] However, if the change condition is met (step S13: YES), the brake torque coefficient calculation section 31 determines a new brake torque coefficient based on the multiple brake torque coefficient candidates and sends a message to the pressure command value calculation section 36 to change the determined brake torque coefficient (step S14), and the processing returns to the top. As a result, the pressure command value calculation section 36, which has been notified of the new brake torque coefficient, calculates a pressure command value using the brake torque coefficient adapted to the state of vehicle 1 in the subsequent processing, so that the braking of vehicle 1 can be controlled with high precision.

[0077] It should be noted that the present invention is not limited to the aforementioned embodiment, but can be modified and implemented in a suitable manner without deviating from the scope of protection of the present invention.

[0078] For example, in the previously mentioned embodiment, the brake control for controlling the automatic parking of the vehicle 1 is mainly described, but the present invention is not limited to this, but can, for example, be applied to the brake control for movement to follow a vehicle ahead or the brake control in the event of stopping in order to prevent a collision with a vehicle ahead.

[0079] Furthermore, in the aforementioned embodiment, the brake ECU 30 includes the functional section that learns and changes the braking torque coefficient, but at least part of the functional section or the processing performed by the functional section can be achieved by another ECU. Reference symbol list 1 vehicle 10 wheels 11 Brake device 12 Wheel speed sensor 13 main cylinders 17 Main pressure sensor 30 Brake ECU 31 Calculation section for the braking torque coefficient 36 Print command value calculation section 44 G-sensor, accelerometer

Claims

[1] Brake control device for a vehicle (1) comprising a brake device (11) which can adjust a braking force depending on the supplied hydraulic pressure, wherein the vehicle (1) comprises: a hydraulic pressure sensor (17) configured to measure the hydraulic pressure supplied to the brake device (11); and an acceleration information sensor configured to detect vehicle acceleration (1) and measure acceleration information, the brake control device includes: a hydraulic pressure supply control section configured to determine a hydraulic pressure to be supplied to the brake device (11) at a time of deceleration of the vehicle (1) based on a preset coefficient and to cause the hydraulic pressure to be supplied to the brake device (11); and a coefficient change section (31) configured to learn a coefficient candidate that is a candidate for changing the coefficient, and to change the coefficient based on a relationship between the hydraulic pressure and the acceleration based on the acceleration information in the coefficient candidate, wherein the coefficient change section (31) is designed to learn the coefficient candidate based on the relationship between the hydraulic pressure and the acceleration based on the acceleration information in a case where the vehicle (1) meets a predetermined driving condition, wherein the predetermined driving condition includes that the vehicle (1) has a predetermined speed or less and / or that the vehicle (1) has a predetermined acceleration or less, wherein the vehicle (1) comprises, as an acceleration information sensor, an acceleration sensor (44) configured to detect acceleration of the vehicle (1) and a wheel speed sensor (12) configured to detect wheel speed of the vehicle (1), characterized by , that the predetermined driving condition includes that the vehicle (1) is not driving on an inclined surface or that the vehicle (1) is not driving on a road surface with low friction, and the coefficient change section (31) is designed to determine that the vehicle (1) is not driving on an inclined surface or that the vehicle (1) is not driving on a road surface with low friction, based on the fact that a difference between a first acceleration detected by the acceleration sensor (44) and a second acceleration detected based on the wheel speed of the wheel speed sensor (12) is a predetermined value or less. [2] Brake control device according to claim 1, wherein the coefficient change section (31) is designed to calculate a plurality of coefficient candidates based on a relationship between the hydraulic pressure and the acceleration at a time point of a plurality of braking events satisfying the predetermined driving condition, and to determine a coefficient candidate that should change the coefficient based on the plurality of coefficient candidates. [3] Brake control device according to claim 2, wherein the coefficient change section (31) is designed to determine, on the basis of the plurality of coefficient candidates, whether the coefficient should be changed. [4] Brake control device according to claim 3, wherein the coefficient change section (31) is designed to determine to change the coefficient when the probability that a value of the plurality of coefficient candidates falls within a predetermined range is equal to or greater than predetermined. [5] Brake control device according to claim 1, wherein the hydraulic pressure supply control section is designed to determine the hydraulic pressure in a case of automatic parking of the vehicle (1) and when the driving condition includes the predetermined speed or less, which is assumed in a case of automatic parking of the vehicle (1). [6] Brake control device according to any one of claims 1 to 5, comprising: a memory section (37) configured to store an initial coefficient, which is a coefficient in a case where a friction element of the braking device (11) of the vehicle (1) is in an initial state, wherein the coefficient change section (31) is designed to change the coefficient to the initial coefficient stored in the storage section (37) when the friction element of the brake device (11) is changed.

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