Braking control device

Abstract

To provide a braking control device capable of preventing excess and deficiency of braking force output by a brake device with respect to a request of brake request deceleration gradient information, and realizing vehicle braking intended by the brake request deceleration gradient information.SOLUTION: A braking control device 20 commands a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information indicating a time transition characteristic of deceleration of a vehicle requested from vehicle side control devices 11, 12 to a brake device 30. The braking control device 20 calculates a deceleration command value obtained by correcting a reference deceleration as a deceleration requested by the brake request deceleration gradient information such that a difference between a total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of the braking control to the current calculation timing and a total amount of braking force output by the brake device 30 according to the deceleration command value instructed during that time is compensated after the current calculation timing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a braking control device. [Background technology]

[0002] Conventionally, automatic braking systems are known that detect the vehicle's driving state and objects around the vehicle and automatically apply the brakes to the vehicle. The automatic braking system described in Patent Document 1 calculates a "brake-requested deceleration gradient" that indicates the time transition characteristics of the host vehicle's deceleration based on the driving state of the host vehicle and the driving state of a vehicle ahead of the host vehicle. Then, a braking control device calculates a "deceleration command value" that generates a braking force that corresponds to the brake-requested deceleration gradient, and issues the command to a brake actuator. Note that in Patent Document 1, the "brake-requested deceleration gradient" is referred to as a "target deceleration," and the "deceleration command value" is referred to as a "control signal." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2715798 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a braking control device typically calculates a deceleration command value based on the brake request deceleration gradient at each calculation timing from the start of braking control and issues the command to the brake device. Therefore, the deceleration command value is updated at each calculation timing, and the deceleration command value calculated at the immediately preceding calculation timing is maintained between calculation timings (hereinafter referred to as the "calculation interval"). Therefore, if the brake request deceleration gradient increases deceleration over time, the braking force output by the brake device may be insufficient with time between calculation timings compared to the braking force based on the deceleration requested by the brake request deceleration gradient. Note that "deceleration" refers to negative acceleration, and "deceleration increasing" refers to an increase in the absolute value of acceleration on the negative side.

[0005] However, if the braking request deceleration gradient increases over time, changing the braking request deceleration gradient to a steeper gradient would cause the vehicle to stop more quickly. However, this would result in the braking force output by the brake device being greater than the braking force based on the deceleration requested by the original braking request deceleration gradient, resulting in sudden braking. Therefore, changing the braking request deceleration gradient to a steeper gradient is not desirable.

[0006] In consideration of the above points, the present disclosure aims to provide a braking control device that can prevent the braking force output by the brake device from being excessive or insufficient in response to the request of the brake request deceleration gradient information, and can achieve the vehicle braking intended by the brake request deceleration gradient information. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a braking control device that issues a deceleration command value to a braking device (30) at each calculation timing based on brake-requested deceleration gradient information indicating a time transition characteristic of a deceleration of a vehicle requested from a vehicle-side control device (11, 12) includes: A deceleration command value is calculated by correcting the reference deceleration as the deceleration required by the brake request deceleration gradient information so as to compensate for the difference between the total amount of braking force based on the deceleration required by the brake request deceleration gradient information from the start of braking control to the current calculation timing and the total amount of braking force output by the brake device based on the deceleration command value issued from the start of braking control to the current calculation timing onwards.

[0008] This allows the calculation of a deceleration command value that can compensate for the excess or deficiency of the braking force output by the brake device relative to the braking force based on the deceleration requested by the brake request deceleration gradient information. This makes it possible to bring the braking force output by the brake device closer to the braking force based on the deceleration requested by the brake request deceleration gradient information. Therefore, this brake control device can achieve vehicle braking as intended by the brake request deceleration gradient information. Furthermore, as described above, if the braking request deceleration gradient increases deceleration over time, changing the braking request deceleration gradient to a steeper gradient will cause the vehicle to stop sooner but will result in sudden braking. In contrast, this braking control device can prevent sudden braking by issuing to the brake device a deceleration command value that can achieve the vehicle braking intended by the braking request deceleration gradient information, without changing the braking request deceleration gradient to a steeper gradient.

[0009] The reference symbols in parentheses attached to each component etc. indicate an example of the correspondence between the component etc. and the specific components etc. described in the embodiments described later. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a schematic configuration of a braking control device according to a first embodiment. [Figure 2] 4 is a graph showing a deceleration command value calculated at each calculation timing by the braking control device of the first comparative example based on brake request deceleration gradient information. [Figure 3]4 is a graph showing a deceleration command value calculated at each calculation timing by the braking control device according to the first embodiment based on brake request deceleration gradient information. [Figure 4] 4 is a graph for explaining a method in which the brake control device according to the first embodiment calculates a deceleration command value at the current calculation timing. [Figure 5] 5 is a graph illustrating, together with FIG. 4, a method for the brake control device according to the first embodiment to calculate a deceleration command value at the current calculation timing. [Figure 6] 4 is a flowchart for explaining a process in which the brake control device according to the first embodiment calculates a deceleration command value. [Figure 7] 4 is a flowchart for explaining in more detail the process of calculating a deceleration command value by the brake control device according to the first embodiment. [Figure 8] FIG. 6 is a block diagram showing a schematic configuration of a braking control device according to a second embodiment. [Figure 9] FIG. 10 is a block diagram showing a schematic configuration of a braking control device according to a third embodiment. [Figure 10] FIG. 10 is a block diagram showing a schematic configuration of a braking control device according to a fourth embodiment. [Figure 11] 10 is a graph showing deceleration command values ​​calculated at each calculation timing based on brake request deceleration gradient information by the braking control devices of the first and second comparative examples. [Figure 12] 10 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to a fifth embodiment. [Figure 13] 10 is a flowchart illustrating a process for calculating a deceleration command value by a braking control device according to a fifth embodiment. [Figure 14] 13 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to a sixth embodiment. [Figure 15] 13 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to a seventh embodiment. [Figure 16] 10 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device of a third comparative example. [Figure 17] 13 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to a ninth embodiment. [Figure 18] 10 is a graph showing deceleration command values ​​calculated at each calculation timing based on brake request deceleration gradient information by braking control devices of a third comparative example and a fourth comparative example. [Figure 19] 13 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to a tenth embodiment. [Figure 20] 19 is a graph showing a deceleration command value calculated at each calculation timing based on brake request deceleration gradient information by a braking control device according to an eleventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals, and description thereof will be omitted.

[0012] (First embodiment) A first embodiment will be described. The braking control device of the first embodiment constitutes a part of an automatic braking system. The automatic braking system detects the running state of a vehicle and objects around the vehicle, and automatically brakes the vehicle. This system can automatically brake the vehicle when the vehicle suddenly accelerates due to, for example, mistaking the brake pedal for the accelerator pedal.

[0013] 1, the automatic braking system is made up of various sensors mounted on a vehicle, an electronic control unit 10 (hereinafter referred to as "ECU 10"), a braking device 30, etc. ECU is an abbreviation for Electronic Control Unit.

[0014] The various sensors include, for example, a vehicle speed sensor 1, an acceleration sensor 2, a steering angle sensor 3, a yaw rate sensor 4, and a sonar sensor 5. The vehicle speed sensor 1, the acceleration sensor 2, the steering angle sensor 3, and the yaw rate sensor 4 output detection signals corresponding to the vehicle's speed, acceleration, steering angle, and yaw rate, respectively. The sonar sensor 5 emits ultrasonic waves around the vehicle and receives and analyzes the waves reflected by objects around the vehicle, thereby obtaining information such as the direction of the objects and the distance to the objects. The signals output by the various sensors are input to the ECU 10.

[0015] The ECU 10 is composed of a microcomputer including a processor that performs control processing and arithmetic processing, and memories such as ROM and RAM that store programs, data, etc., and its peripheral circuits. The processor of the ECU 10 performs various control processing and arithmetic processing based on the programs stored in the memory. The processor executes the programs stored in the memory, allowing the ECU 10 to function as an object selection unit 11, a deceleration calculation unit 12, a brake control processing unit 20, etc., which will be described later.

[0016] In the first embodiment, the object selection unit 11 and the deceleration calculation unit 12 correspond to an example of a “vehicle-side control device,” and the brake control processing unit 20 corresponds to an example of a “brake control device.” Therefore, in the first embodiment, the vehicle-side control device and the brake control device are configured by one ECU 10.

[0017] Based on signals input from various sensors, the object selection unit 11 selects an object that the vehicle may approach excessively or reach from among objects present around the vehicle. The deceleration calculation unit 12 determines whether the vehicle will reach the object, the distance between the vehicle and the object, the time required for the vehicle to reach the object, etc. The deceleration calculation unit 12 then calculates a brake request deceleration gradient that indicates the time transition characteristics of the vehicle deceleration requested of the brake device 30 to avoid reaching the object, and transmits this information to the brake control processing unit 20.

[0018] The brake control processing unit 20 calculates a deceleration command value at each calculation timing based on the brake required deceleration gradient information requested from the deceleration calculation unit 12, and issues the deceleration command value to the brake device 30. The calculation method of the deceleration command value calculated by the brake control processing unit 20 will be described later.

[0019] The brake device 30 operates based on a deceleration command value received from the brake control processor 20 and outputs a braking force to brake the vehicle. Various mechanisms can be used for the brake device 30. For example, the brake device 30 may be configured to increase the hydraulic pressure of the brake fluid by operating a master cylinder or a hydraulic pump based on a deceleration command value transmitted from the brake control processor 20, thereby driving wheel cylinders arranged on each wheel and operating the brake pads. Alternatively, for example, the brake device 30 may be configured as an electric brake that drives an electric motor based on the deceleration command value to press brake pads against disc brake rotors, thereby braking each wheel.

[0020] Before explaining the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first embodiment, the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first comparative example will be explained with reference to the graph in Figure 2.

[0021] The vertical axis of Figure 2 represents deceleration, and the horizontal axis represents time. Note that "deceleration" refers to negative acceleration, and "large deceleration" refers to a large absolute value of acceleration on the negative side. 2, the brake request deceleration gradient information is indicated by a dashed dotted line A, and the deceleration command value of the first comparative example is indicated by a thick solid line B. In the first comparative example, the brake request deceleration gradient information increases the deceleration over time, that is, increases the absolute value of the acceleration on the negative side over time.

[0022] As shown in FIG. 2, when braking control is initiated at time T0, the brake control processor 20 of the first comparative example calculates a deceleration command value as indicated by the brake request deceleration gradient information at each of the calculation timings T1, T2, T3, and T4. Because the deceleration command value is updated at each calculation timing, the deceleration command value calculated at the immediately preceding calculation timing is maintained between calculation timings (hereinafter referred to as the "calculation interval"). Therefore, over time between calculation timings, the braking force output by the brake device 30 falls short of the braking force based on the deceleration requested by the brake request deceleration gradient information. In FIG. 2, hatched areas F1 to F4 indicate the amount by which the braking force output by the brake device 30 falls short of the braking force based on the deceleration requested by the brake request deceleration gradient information. Therefore, the brake control processor 20 of the first comparative example has difficulty achieving the vehicle braking intended by the brake request deceleration gradient information.

[0023] A method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first embodiment will be described with reference to the graph of FIG. 3, in comparison with a first comparative example.

[0024] 3, the brake request deceleration gradient information is indicated by a dashed dotted line A, and the deceleration command value of the first embodiment is indicated by a thick solid line C. In the first embodiment, the brake request deceleration gradient information also increases the deceleration over time.

[0025] 3, when braking control is started at time T0, the brake control processor 20 of the first embodiment calculates a deceleration command value at each of calculation timings T1, T2, T3, and T4. At this time, the brake control processor 20 calculates a difference between the total amount of braking force based on the deceleration requested by the brake-requested deceleration gradient information from the start of braking control until the current calculation timing and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time. The brake control processor 20 then calculates a deceleration command value obtained by correcting the reference deceleration as the deceleration requested by the brake-requested deceleration gradient information so as to compensate for the difference from the current calculation timing onward.

[0026] For example, in FIG. 3 , the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control to the calculation timing of time T1 is indicated by the hatched area F1. Because no deceleration command value is calculated from the start of braking control to the calculation timing of time T1, the total amount of braking force output by the brake device 30 during that time is zero. Therefore, the difference between the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control to the calculation timing of time T1 and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time is indicated by area F1. The brake control processor 20 calculates a correction value that can compensate for the difference indicated by area F1 (i.e., the braking force shortage) after the calculation timing of time T1 (specifically, between time T1 and time T2). The brake control processor 20 then sets the value obtained by adding the correction value to the reference deceleration as the deceleration command value at the calculation timing of time T1. In Fig. 3, the reference deceleration calculated by the brake control processor 20 at the calculation timing of time T1 is indicated by arrow α1, the correction value is indicated by arrow α2, and the deceleration command value is indicated by arrow α3. As a result, the braking force deficiency F1 between time T0 and time T1 is compensated for between time T1 and time T2. In Fig. 3, the braking force compensated for between time T1 and time T2 is indicated by area C1.

[0027] Similarly, the braking force deficiency between time T1 and time T2 is compensated for between time T2 and time T3. The braking force deficiency between time T2 and time T3 is compensated for between time T3 and time T4. The braking force compensated for between time T2 and time T3 is indicated by area C2. The braking force compensated for between time T3 and time T4 is indicated by area C3. In this way, the braking control device of the first embodiment can achieve vehicle braking as intended by the brake required deceleration gradient information.

[0028] A method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first embodiment will be specifically described with reference to the graphs of FIGS.

[0029] 4 and 5, the brake request deceleration gradient information is indicated by a dashed line A, and the deceleration command value of the first embodiment is indicated by a thick solid line C. Furthermore, the deceleration command value calculated according to the brake request deceleration gradient information at each calculation timing as in the first comparative example is indicated by a dashed line B.

[0030] In this explanation, it is assumed that when braking control is started at time T0, the brake control processor 20 calculates a deceleration command value at each of the calculation timings of times T2, T4, and T6. In this explanation, the calculation method for the deceleration command value at the calculation timing of time T4 will be explained as an example. That is, time T4 is the current calculation timing, and time T2 is the previous calculation timing.

[0031] At the current calculation timing (i.e., time T4), the brake control processing unit 20 first calculates the braking force shortage in the previous cycle from the previous calculation timing to the current calculation timing, i.e., the previous cycle braking force shortage, based on the following (Equation 1). Braking force shortage in previous cycle = Brake request deceleration gradient (i.e., gradient of dashed dotted line A) × previous cycle × previous cycle ÷ 2 (Equation 1) In FIG. 4, the previous periodic braking force deficiency is indicated by an area F2.

[0032] Next, the brake control processing unit 20 calculates the amount of braking force compensated for in the previous cycle, that is, the previous cycle braking force compensation amount, based on the following (Equation 2). Previous cycle braking force compensation amount = Previous correction value × Previous cycle (Equation 2) In FIG. 5, the previous periodic braking force compensation amount is indicated by an area C1, and the previous correction value is indicated by an arrow α2.

[0033] Next, the brake control processing unit 20 calculates the total amount of braking force deficiency at the current calculation timing, that is, the current value of the total amount of braking force deficiency, based on the following (Equation 3). Current braking force deficit total amount = Previous braking force deficit total amount + Previous period braking force deficit amount - Previous period braking force compensation amount (Equation 3) The current value of the total braking force deficiency corresponds to the difference between the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control to the current calculation timing, and the total amount of braking force output by the brake device 30 based on the deceleration command value commanded during that time.

[0034] Next, the brake control processing unit 20 calculates a correction value at the current calculation timing, that is, a current correction value, based on the following (Equation 4). Current correction value = Current braking force deficiency total value ÷ Previous cycle (Equation 4) In Fig. 5, the current correction value is indicated by an arrow α12. In the above equation 4, the brake control processor 20 assumes that the next cycle from the current calculation timing to the next calculation timing is approximately the same time as the previous cycle, and uses the previous cycle to calculate the current correction value. This makes it possible to calculate a more appropriate correction value even if there is a possibility of fluctuation in the cycle between calculation timings.

[0035] Next, the brake control processing unit 20 calculates the deceleration command value at the current calculation timing based on the following (Equation 5). Deceleration command value = Reference deceleration + Current correction value (Equation 5) In FIG. 5, the deceleration command value at the current calculation timing is indicated by an arrow α13, and the reference deceleration is indicated by an arrow α11.

[0036] Finally, the brake control processor 20 stores the "current correction value" in memory as the "previous correction value" to be used at the next calculation timing. Also, the brake control processor 20 stores the "current braking force deficit total amount" in memory as the "previous braking force deficit total amount"

[0037] Next, a method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first embodiment will be described with reference to the flowchart of FIG. This control process is repeatedly executed at a predetermined control period when the main switch of the vehicle is turned on.

[0038] First, in step S10, the brake control processor 20 determines whether or not there is a brake control request. If there is no brake control request, the process proceeds to step S60, where the brake control processor 20 sets the deceleration command value to 0 and temporarily ends the process. On the other hand, if there is a brake control request, the process proceeds to step S20. In step S20, the brake control processor 20 calculates a reference deceleration based on the brake request deceleration gradient information at the current calculation timing.

[0039] Next, in step S30, the brake control processor 20 calculates the difference between the total amount of braking force based on the deceleration requested by the brake requested deceleration gradient information from the start of braking control to the current calculation timing, and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time. This difference can be calculated, for example, using the above-mentioned formulas 1 to 3. The difference corresponds to the "current value of total braking force shortage" in formula 3.

[0040] Next, in step S40, the brake control processor 20 calculates a correction value (i.e., a current correction value) that can compensate for the difference calculated in step S30 from the current calculation timing onward. The current correction value can be calculated, for example, using the above formula 4. That is, the current correction value is the value obtained by dividing the difference (i.e., the current value of the total braking force shortage amount) by the time of the previous cycle.

[0041] Next, in step S50, the brake control processor 20 corrects the reference deceleration calculated in step S20 with the current correction value calculated in step S40 to calculate a deceleration command value. The deceleration command value can be calculated, for example, using the above-mentioned equation 5. Then, the brake control processor 20 issues the deceleration command value to the brake device 30. The brake control processor 20 repeatedly executes the processes of steps S10 to S60 at a predetermined control cycle while the main switch of the vehicle is turned on.

[0042] Next, the control process described in steps S10 to S60 above will be described in more detail with reference to the flowchart of FIG.

[0043] In the flowchart of Fig. 7, the processes of steps S10, S20, and S60 are the same as those explained in Fig. 6. The processes of steps S31 to S33 in Fig. 7 are a detailed explanation of the process of step S30 in Fig. 6.

[0044] In step S31 following step S20, the brake control processor 20 calculates the previous period braking force shortage amount using the above-mentioned formula 1. In step S32, the brake control processor 20 calculates the previous-period braking force compensation amount using the above-mentioned formula 2. In step S33, the brake control processor 20 calculates the current total braking force shortage value using the above-mentioned formula 3.

[0045] Next, in step S41, the brake control processor 20 calculates, by the above-mentioned formula 4, a current correction value that can compensate for the current value of the total braking force shortage (ie, the difference amount) calculated in step S33 after the current calculation timing. Subsequently, in step S51, the brake control processor 20 corrects the reference deceleration calculated in step S20 with the current correction value calculated in step S41 to calculate a deceleration command value.

[0046] Thereafter, in step S52, the brake control processor 20 stores the "current braking force deficit total amount value" in memory as the "previous braking force deficit total amount value" and stores the "current correction value" in memory as the "previous correction value."

[0047] When performing the above-described calculations, the brake control processing unit 20 functions as a reference deceleration calculation unit, a difference amount calculation unit, a correction value calculation unit, and a command value calculation unit by having the processor execute a program stored in the memory. Therefore, it can be said that the brake control processing unit 20 has a reference deceleration calculation unit, a difference amount calculation unit, a correction value calculation unit, and a command value calculation unit as functional units. Specifically, step S20 corresponds to the processing by the reference deceleration calculation unit. Steps S30 to S33 correspond to the processing by the difference amount calculation unit. Steps S40 and S41 correspond to the processing by the correction value calculation unit. Steps S50 and S51 correspond to the processing by the command value calculation unit.

[0048] The braking control device (that is, the brake control processing unit 20) of the first embodiment described above provides the following operational effects.

[0049] (1) The braking control device of the first embodiment calculates the difference between the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control to the current calculation timing and the total amount of braking force output by the braking device 30 based on the deceleration command value issued during that time.The braking control device then calculates a deceleration command value obtained by correcting the reference deceleration requested by the brake request deceleration gradient information so as to compensate for the difference from the current calculation timing onwards. This allows a deceleration command value to be calculated that can compensate for the excess or deficiency of the braking force output by the brake device 30 relative to the braking force based on the deceleration requested by the brake request deceleration gradient information. Therefore, it is possible to make the braking force output by the brake device 30 closer to the braking force based on the deceleration requested by the brake request deceleration gradient information. Therefore, this brake control device can achieve vehicle braking as intended by the brake request deceleration gradient information. In addition, the braking control device can prevent sudden braking by instructing the braking device 30 to use a deceleration command value that can achieve the vehicle braking intended by the braking request deceleration gradient information, without making a steep change to the braking request deceleration gradient.

[0050] (2) In the first embodiment, when the total amount of braking force output by the brake device 30 based on the deceleration command value commanded during the period from the start of braking control to the current calculation timing is smaller than the total amount of braking force based on the deceleration requested by the brake required deceleration gradient information, the brake control device calculates a deceleration command value that is larger than the reference deceleration at the current calculation timing in accordance with the difference amount. According to this, when the brake request deceleration gradient information indicates that the deceleration increases over time, if the reference deceleration calculated at each calculation timing is used as the deceleration command value, there is a risk that the braking force output by the brake device 30 between the calculation timings will be insufficient. Therefore, by calculating a deceleration command value that increases the reference deceleration at the calculation timing in accordance with the difference amount, it is possible to compensate for the insufficiency of the braking force output by the brake device 30 in response to the request from the brake request deceleration gradient information, and it is possible to achieve the vehicle braking intended by the brake request deceleration gradient information.

[0051] (3) The braking control device of the first embodiment has, as its functional units, a reference deceleration calculation unit, a difference calculation unit, a correction value calculation unit, and a command value calculation unit. The reference deceleration calculation unit calculates a reference deceleration as the deceleration required by the brake-requested deceleration gradient information for each calculation timing. The difference calculation unit calculates a difference between the total amount of braking force based on the deceleration required by the brake-requested deceleration gradient information from the start of braking control to the current calculation timing and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time. The correction value calculation unit calculates a correction value that makes it possible to compensate for the difference calculated by the difference calculation unit after the current calculation timing. The command value calculation unit corrects the reference deceleration calculated by the reference deceleration calculation unit at the current calculation timing with the correction value, and calculates a deceleration command value. According to this, the brake control device functions as a reference deceleration calculation section, a difference amount calculation section, a correction value calculation section, and a command value calculation section by the processor executing the program stored in the memory.

[0052] (4) In the first embodiment, the correction value calculation unit included in the braking control device divides the difference amount calculated by the difference amount calculation unit by the time of the previous cycle to obtain the current correction value. According to this, by assuming that the next period is approximately the same length as the previous period and using the previous period to calculate the current correction value, a more appropriate correction value can be calculated even if there may be fluctuations in the period between calculation timings.

[0053] (Second to fourth embodiments) The second to fourth embodiments are modifications to the first embodiment in the configuration of an automatic braking system in which a braking control device is used, but the rest is the same as the first embodiment, so only the parts that differ from the first embodiment will be described.

[0054] (Second embodiment) As shown in FIG. 8, in the second embodiment, a camera 6, a millimeter wave radar 7, and a LIDAR 8 are exemplified as detection sensors in addition to the sonar sensor 5 described in the first embodiment.

[0055] The camera 6 is an imaging device that periodically or irregularly captures and outputs image data of the area around the vehicle. The millimeter-wave radar 7 emits millimeter-wave radio waves and receives and analyzes the reflected waves from objects around the vehicle to acquire various information, such as the direction of the object, the distance to the object, and the relative speed to the object. The LIDAR 8 emits laser light and receives and analyzes the reflected light from objects around the vehicle to acquire various information, such as the direction of the object, the distance to the object, the relative speed to the object, and the shape of the object. LIDAR stands for Light Detection and Ranging or Laser Imaging Detection and Ranging. Output signals from each detection sensor are transmitted to the driving assistance ECU 10. The driving assistance ECU 10 can function as an object selection unit 11, a deceleration calculation unit 12, a brake control processing unit 20, and the like.

[0056] The second embodiment described above can also achieve the same effects as the first embodiment, etc. In addition, in the second embodiment, the driving assistance ECU 10 can perform brake control processing.

[0057] (Third embodiment) As shown in FIG. 9 , in the third embodiment, a brake control processor 20 serving as a braking control device is provided on the brake device 30 side. Specifically, the brake control processor 20 is incorporated into an ECU provided in the brake device 30. Therefore, in the example of the third embodiment, the vehicle-side control device and the braking control device are configured as different ECUs. Brake request deceleration gradient information is transmitted from the driving assistance ECU 10 to the ECU provided in the brake device 30 (i.e., the brake control processor 20). The brake control processor 20 calculates a deceleration command value and drives the brake device 30.

[0058] The third embodiment described above can also achieve the same effects as the first embodiment, etc. Furthermore, in the third embodiment, the brake control process can be performed within the brake device 30.

[0059] (Fourth embodiment) As shown in Fig. 10, in the fourth embodiment, a brake control processing unit 20 serving as a brake control device is provided in an application ECU 40. Brake request deceleration gradient information is transmitted to the application ECU 40 from the driving assistance ECU 10. The application ECU 40 calculates a deceleration command value and transmits it to the brake device 30. In the example of the fourth embodiment as well, the vehicle-side control device and the brake control device are configured as different ECUs.

[0060] The fourth embodiment described above can also achieve the same effects as the first embodiment, etc. Furthermore, in the fourth embodiment, the application ECU 40 can perform brake control processing.

[0061] (Fifth embodiment) The fifth embodiment will be described. The fifth embodiment is different from the first embodiment in that the method of calculating the deceleration command value calculated by the brake control processing unit 20 is partially changed, but the rest is the same as the first embodiment, so only the differences from the first embodiment will be described.

[0062] Before explaining the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the fifth embodiment, the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the first and second comparative examples will be explained with reference to the graph in Figure 11.

[0063] In Fig. 11, the brake request deceleration gradient information is indicated by a dashed line A. The deceleration command value calculated by the brake control processing unit 20 of the first comparative example is indicated by a broken line B. The deceleration command value calculated by the brake control processing unit 20 of the second comparative example is indicated by a solid line D.

[0064] The brake control processing unit 20 of the first comparative example calculates a deceleration command value as indicated in the brake required deceleration gradient information. In contrast, the brake control processing unit 20 of the second comparative example calculates a deceleration command value using the same calculation method as the brake control processing unit 20 of the first embodiment. However, the brake control processing units 20 of both the first and second comparative examples have larger fluctuations in the cycle between calculation timings compared to the first embodiment.

[0065] 11, the brake control processor 20 of both the first and second comparative examples calculates a deceleration command value at each of the calculation timings of times T5, T6, and T11. In the following description, time T5 will be referred to as the first calculation timing, time T6 as the second calculation timing, and time T11 as the third calculation timing, as appropriate.

[0066] Specifically, as shown by solid line D, the brake control processing unit 20 of the second comparative example first calculates the current braking force shortage total amount value at the first calculation timing (i.e., time T5) using the above equations 1 to 3. At the first calculation timing, the current braking force shortage total amount value matches the total amount of braking force based on the deceleration requested by the brake requested deceleration gradient information between time T0 and time T5. Next, the brake control processing unit 20 uses the above equation 4 to divide the current braking force shortage total amount value by the previous cycle (i.e., time T0 to time T5) to obtain a current correction value. Then, the brake control processing unit 20 uses the above equation 5 to add the current correction value to the reference deceleration to calculate the deceleration command value.

[0067] Next, the brake control processing unit 20 of the second comparative example calculates the current total braking force shortage value using the above formulas 1 to 3 at the second calculation timing (i.e., time T6). The period between the first calculation timing and the second calculation timing (i.e., time T5 to time T6) is shorter (specifically, approximately one-fifth) than the period between the start of brake control and the first calculation timing (i.e., time T0 to time T5). Therefore, at the time of the second calculation timing, the total braking force shortage value from time T0 to time T5 has not been fully compensated for, so the current total braking force shortage value at the second calculation timing is large. Next, the brake control processing unit 20 uses the above formula 4 to divide the current total braking force shortage value by the previous period (i.e., time T5 to time T6) to obtain the current correction value. At this time, because the current total braking force shortage value is large and the previous period is short, the current correction value is very large. Then, when the brake control processing unit 20 calculates the deceleration command value by adding the current correction value to the reference deceleration using the above equation 5, the deceleration command value at two calculation timings becomes much larger than the deceleration command value at one calculation timing.

[0068] Next, at the third calculation timing (i.e., time T11), the brake control processing unit 20 of the second comparative example calculates the current total braking force shortage value using the above-mentioned formulas 1 to 3. The period between the second calculation timing and the third calculation timing (i.e., time T6 to time T11) is longer (specifically, approximately five times longer) than the period between the first calculation timing and the second calculation timing (i.e., time T5 to time T6). Therefore, at the third calculation timing, the total amount of braking force output by the brake device 30 during the period from time T0 to time T11 is greater than the total amount of braking force based on the deceleration requested by the brake requested deceleration gradient information. Therefore, the current total braking force shortage value is a negative value (i.e., a value indicating that the braking force is excessive). Next, the brake control processor 20 divides the current braking force shortage total amount by the previous cycle (i.e., time T6 to time T11) using the above-mentioned formula 4 to obtain a current correction value, which becomes a negative deceleration (in other words, the current correction value is a positive acceleration).Then, when the brake control processor 20 calculates a deceleration command value by adding the current correction value to the reference deceleration using the above-mentioned formula 5, the deceleration command values ​​at the three calculation timings become much smaller than the deceleration command values ​​at the two calculation timings.

[0069] In this way, in the second comparative example, when there is a large variation in the cycle between calculation timings, the correction value fluctuates greatly. When the deceleration command value increases sharply, as at the second calculation timing (i.e., time T6), the vehicle is suddenly braked, and the vehicle behavior becomes unstable. On the other hand, when the deceleration command value decreases sharply, as at the third calculation timing (i.e., time T11), the vehicle braking weakens, resulting in so-called brake slippage.

[0070] The method of calculating the deceleration command value calculated by the brake control processing unit 20 of the fifth embodiment will be described with reference to the graph of FIG. 12, in comparison with the second comparative example.

[0071] In Fig. 12, the deceleration command value calculated by the brake control processing unit 20 of the fifth embodiment is indicated by a thick solid line E. The brake control processing unit 20 of the fifth embodiment also calculates a deceleration command value at each of the calculation timings of times T5, T6, and T11. Note that in Fig. 12 as well, the brake required deceleration gradient information is indicated by a dashed line A, the deceleration command value calculated by the brake control processing unit 20 of the first comparative example is indicated by a dashed line B, and the deceleration command value calculated by the brake control processing unit 20 of the second comparative example is indicated by a solid line D.

[0072] The brake control processor 20 of the fifth embodiment is configured to be capable of calculating an upper limit guard value and a lower limit guard value for the correction value, in contrast to the brake control processor 20 of the first embodiment. Specifically, when calculating the current correction value using Equation 4, if the value obtained by dividing the current braking force deficit total amount by the previous cycle falls outside the range between the upper limit guard value and the lower limit guard value, the brake control processor 20 changes the current correction value to a value within that range. For example, if the value obtained by dividing the current braking force deficit total amount by the previous cycle is greater in absolute value than the upper limit guard value, the brake control processor 20 sets the upper limit guard value as the current correction value. Furthermore, for example, if the value obtained by dividing the current braking force deficit total amount by the previous cycle is smaller in absolute value than the lower limit guard value, the brake control processor 20 sets the lower limit guard value as the current correction value.

[0073] In the fifth embodiment, the upper and lower limit guard values ​​are set as follows. Upper limit guard value = Brake request acceleration gradient x Ideal cycle Lower limit guard value = 0 The ideal period can be the shortest period in design.

[0074] By setting the upper limit guard as described above, it is possible to prevent the corrected deceleration command value from becoming too high compared to the reference deceleration. If the period between time T5 and time T6 in Fig. 12 is considered to be an ideal period, it is possible to make the corrected deceleration command value at the current calculation timing (e.g., time T5) ≦ the reference deceleration at the next calculation timing (e.g., time T6). Furthermore, by setting the lower limit guard to 0, the occurrence of so-called brake failure can be suppressed.

[0075] Next, a method for calculating the deceleration command value calculated by the brake control processing unit 20 of the fifth embodiment will be described with reference to the flowchart of FIG.

[0076] In the flowchart of FIG. 13, the processes in steps S10, S20, S31, S32, S33, S41, S51, S52, and S60 are the same as those described in FIG.

[0077] In step S42 following step S41, the brake control processor 20 executes guard processing of the current correction value. That is, in step S42, if the value calculated in step S41 falls outside the range from the upper guard value to the lower guard value, the brake control processor 20 changes the value to fall within that range and sets the current correction value as such. In the processing of steps S41 and S42, the brake control processor 20 functions as a correction value calculation unit.

[0078] The braking control device (i.e., brake control processing unit 20) of the fifth embodiment described above is configured to store or be able to calculate upper and lower limit guard values ​​for the correction value in advance. If the value calculated using the above formula 4 falls outside the range from the upper limit guard value to the lower limit guard value, the correction value calculation unit sets a value within the range from the upper limit guard value to the lower limit guard value. Note that the value calculated using the above formula 4 corresponds to the value obtained by dividing the difference amount calculated by the difference amount calculation unit (i.e., the current value of the total braking force shortage amount) by the time of the previous cycle. According to this, even if there is a large fluctuation in the cycle between calculation timings, by limiting the correction value to a value within the range from the upper limit guard value to the lower limit guard value, it is possible to prevent a sudden increase or decrease in the deceleration command value, thereby preventing the vehicle's behavior from becoming unstable due to sudden braking and preventing so-called brake slippage due to slack in vehicle braking.

[0079] (Sixth embodiment) The sixth embodiment will be described. The sixth embodiment differs from the fifth embodiment in that the method for setting the upper and lower limit guard values ​​is changed, but the rest is the same as the fifth embodiment, so only the differences from the fifth embodiment will be described.

[0080] A calculation method of the deceleration command value calculated by the brake control processing unit 20 of the sixth embodiment will be described with reference to the graph in Fig. 14. In Fig. 14, the deceleration command value calculated by the brake control processing unit 20 of the sixth embodiment is indicated by a thick solid line F. Note that in Fig. 14 as well, the brake required deceleration gradient information is indicated by a dashed line A, the deceleration command value calculated by the brake control processing unit 20 of the first comparative example is indicated by a dashed line B, and the deceleration command value calculated by the brake control processing unit 20 of the second comparative example is indicated by a solid line D.

[0081] 14, the upper limit guard value of the correction value is indicated by a two-dot chain line G. In the brake control processing unit 20 of the sixth embodiment, as indicated by the two-dot chain line G, the upper limit guard value of the correction value is set to a line obtained by adding a predetermined gradient θ to the brake request deceleration gradient information.

[0082] By setting the upper limit guard as described above, it is possible to prevent the corrected deceleration command value from becoming too high relative to the reference deceleration. That is, as shown at times T5, T6, and T11 in Fig. 14, it is possible to make the corrected deceleration command value ≦ the two-dot chain line G at each calculation timing.

[0083] The correction value for the lower limit guard value may be set to 0. By setting the lower limit guard, it is possible to prevent the occurrence of so-called brake failure.

[0084] The sixth embodiment described above can also achieve the same effects as the fifth embodiment and the like.

[0085] (Seventh embodiment) The seventh embodiment will be described. The seventh embodiment differs from the fifth embodiment in that the method for setting the upper and lower limit guard values ​​is changed, but the rest of the seventh embodiment is the same as the fifth embodiment, so only the differences from the fifth embodiment will be described.

[0086] A calculation method of the deceleration command value calculated by the brake control processing unit 20 of the seventh embodiment will be described with reference to the graph in Fig. 15. In Fig. 15, the deceleration command value calculated by the brake control processing unit 20 of the seventh embodiment is indicated by a thick solid line H. Note that in Fig. 15 as well, the brake required deceleration gradient information is indicated by a dashed line A, the deceleration command value calculated by the brake control processing unit 20 of the first comparative example is indicated by a dashed line B, and the deceleration command value calculated by the brake control processing unit 20 of the second comparative example is indicated by a solid line D.

[0087] In the seventh embodiment, the upper and lower limit guard values ​​are set as follows. Upper limit guard value = Brake request acceleration gradient x Ideal period x Constant In the example of FIG. 15, the constant is set to 4. The upper limit is set to the correction value.

[0088] On the other hand, the lower limit guard value is set to the deceleration command value, not the correction value. Specifically, the lower limit guard value is set as follows: the deceleration command value corrected at the current calculation timing is equal to or greater than the deceleration command value corrected at the previous calculation timing.

[0089] In the seventh embodiment, by setting the upper limit guard as described above, the deceleration command value can be made larger than in the fifth and sixth embodiments, and a shortage of braking force can be dealt with more appropriately. Furthermore, by setting the lower limit guard as described above, even if the braking force becomes excessive, the deceleration command value corrected at the current calculation timing will maintain the deceleration command value corrected at the previous calculation timing, thereby preventing the occurrence of so-called brake slippage.

[0090] (Eighth embodiment) An eighth embodiment will be described. The eighth embodiment is similar to the fifth embodiment in other respects except for the method of setting the upper and lower limit guard values, and therefore only the differences from the fifth embodiment will be described.

[0091] In the eighth embodiment, the brake control processor 20 may store in advance in its own memory upper and lower limit guard values ​​of the correction value as predetermined values. That is, the correction value is set to fall within the range from the lower limit guard value to the upper limit guard value. This prevents a sudden increase or decrease in the deceleration command value even if there is a large fluctuation in the cycle between calculation timings, thereby preventing the vehicle's behavior from becoming unstable due to sudden braking and preventing so-called brake slippage due to slack in vehicle braking.

[0092] (Ninth embodiment) A ninth embodiment will be described. An automatic braking system using the braking control device of the ninth embodiment is a system that can detect the driving state of the host vehicle and the driving state of a vehicle ahead of the host vehicle and automatically apply the brakes to the host vehicle, for example, during driving control in a traffic jam.

[0093] Before explaining the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the ninth embodiment, the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the third comparative example will be explained with reference to the graph in Figure 16.

[0094] 16, the brake request deceleration gradient information is indicated by a dashed dotted line A, and the deceleration command value of the third comparative example is indicated by a thick solid line I. In the third comparative example, the brake request deceleration gradient information decreases the deceleration over time, that is, brings the absolute value of the acceleration on the negative side closer to 0 over time.

[0095] As shown in FIG. 16, the brake control processor 20 of the third comparative example calculates a deceleration command value as indicated by the brake request deceleration gradient information at each of the calculation timings T0, T1, T2, T3, and T4. Therefore, as time passes between the calculation timings, the braking force output by the brake device 30 becomes excessive relative to the braking force based on the deceleration requested by the brake request deceleration gradient information. In FIG. 16, the hatched areas F5 to F8 indicate the amount by which the braking force output by the brake device 30 becomes excessive relative to the braking force based on the deceleration requested by the brake request deceleration gradient information. Therefore, the brake control processor 20 of the third comparative example has difficulty achieving the vehicle braking intended by the brake request deceleration gradient information.

[0096] The method of calculating the deceleration command value calculated by the brake control processing unit 20 of the ninth embodiment will be described with reference to the graph of FIG. 17, in comparison with the third comparative example.

[0097] 17, the brake request deceleration gradient information is indicated by a dashed dotted line A, and the deceleration command value of the ninth embodiment is indicated by a thick solid line J. In the ninth embodiment, the brake request deceleration gradient information also reduces the deceleration over time.

[0098] 17, the brake control processor 20 of the ninth embodiment also calculates a deceleration command value at each calculation timing of times T0, T1, T2, T3, and T4. At that time, the brake control processor 20 of the ninth embodiment calculates a difference between the total amount of braking force based on the deceleration requested by the brake required deceleration gradient information from the start of braking control to the current calculation timing and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time. Then, the brake control processor 20 calculates a deceleration command value obtained by correcting the reference deceleration as the deceleration requested by the brake required deceleration gradient information so as to compensate for the difference from the current calculation timing onwards.

[0099] For example, in FIG. 17 , the hatched area F5 indicates the amount of braking force output by the brake device 30 that is excessive relative to the braking force based on the deceleration requested by the brake request deceleration gradient information from time T0 to the calculation timing of time T1. It is assumed that the difference between the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control (not shown) until time T0 and the total amount of braking force output by the brake device 30 based on the deceleration command value issued during that time is zero. The brake control processor 20 calculates a correction value that can reduce the difference indicated by area F5 (i.e., the excessive amount of braking force) after the calculation timing of time T1 (specifically, between time T1 and time T2). The brake control processor 20 then sets the deceleration command value obtained by reducing the reference deceleration by the correction value as the deceleration command value at the calculation timing of time T1. In Fig. 17, the reference deceleration calculated by the brake control processor 20 at the calculation timing of time T1 is indicated by arrow α21, the correction value is indicated by arrow α22, and the deceleration command value is indicated by arrow α23. As a result, the excess braking force F5 between time T0 and time T1 is reduced between time T1 and time T2. In Fig. 17, the braking force reduced between time T1 and time T2 is indicated by area C4.

[0100] Similarly, the excess braking force between time T1 and time T2 is reduced between time T2 and time T3. The excess braking force between time T2 and time T3 is reduced between time T3 and time T4. The braking force reduced between time T2 and time T3 is indicated by area C5. The braking force reduced between time T3 and time T4 is indicated by area C6. In this way, the brake control device of the ninth embodiment can achieve vehicle braking as intended by the brake request deceleration gradient information.

[0101] The braking control device of the ninth embodiment described above calculates a deceleration command value that is smaller than the reference deceleration at the current calculation timing in accordance with the difference amount when the total amount of braking force output by the braking device 30 based on the deceleration command value commanded during the period from the start of braking control to the current calculation timing is greater than the total amount of braking force based on the deceleration requested by the brake required deceleration gradient information. According to this, when the brake request deceleration gradient information indicates that the deceleration decreases over time, if the reference deceleration calculated at each calculation timing is used as the deceleration command value, there is a risk that the braking force output by the brake device 30 between the calculation timings will be excessive. Therefore, by calculating a deceleration command value that reduces the reference deceleration at the calculation timing in accordance with the difference amount, it is possible to eliminate excessive braking force output by the brake device 30 in response to the request of the brake request deceleration gradient information, and to achieve vehicle braking as intended by the brake request deceleration gradient information.

[0102] (Tenth embodiment) The tenth embodiment will be described. The tenth embodiment is different from the ninth embodiment in that the method of calculating the deceleration command value calculated by the brake control processing unit 20 is partially changed, but the rest is the same as the ninth embodiment, so only the differences from the ninth embodiment will be described.

[0103] Before explaining the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the tenth embodiment, the method for calculating the deceleration command value calculated by the brake control processing unit 20 of the third and fourth comparative examples will be explained with reference to the graph in Figure 18.

[0104] 18, the brake request deceleration gradient information is indicated by a dashed line A. The deceleration command value calculated by the brake control processing unit 20 of the third comparative example is indicated by a broken line K. The deceleration command value calculated by the brake control processing unit 20 of the fourth comparative example is indicated by a solid line L.

[0105] The brake control processing unit 20 of the third comparative example calculates the deceleration command value as indicated in the brake required deceleration gradient information. In contrast, the brake control processing unit 20 of the fourth comparative example calculates the deceleration command value using the same calculation method as the brake control processing unit 20 of the ninth embodiment.

[0106] However, the brake control processing unit 20 of the third and fourth comparative examples both have larger fluctuations in the cycle between calculation timings compared to the ninth embodiment. Specifically, as shown in Fig. 18, the brake control processing unit 20 of the third and fourth comparative examples both calculates deceleration command values ​​at calculation timings of times T0, T5, T6, and T11. In the following description, time T5 will be referred to as the first calculation timing, time T6 as the second calculation timing, and time T11 as the third calculation timing, as appropriate.

[0107] In addition, the difference between the total amount of braking force based on the deceleration requested by the brake request deceleration gradient information from the start of braking control (not shown) to time T0 and the total amount of braking force output by the brake device 30 based on the deceleration command value commanded during that time is assumed to be 0.

[0108] In the following explanation, the difference between the total amount of braking force based on the deceleration requested by the brake required deceleration gradient information within a specified time period and the total amount of braking force output by the brake device 30 based on the deceleration command value commanded during that time period will be referred to as the "difference in braking force," "excess braking force," or "deficient braking force."

[0109] As shown by the solid line L, the brake control processing unit 20 of the fourth comparative example calculates the excess amount of braking force from the start of braking control until time T5 at the first calculation timing (i.e., time T5).The brake control processing unit 20 then divides the excess amount of braking force by the previous cycle (i.e., time T0 to time T5) to obtain a current correction value, and corrects the reference deceleration using the current correction value to calculate a deceleration command value.

[0110] Next, at the second calculation timing (i.e., time T6), the brake control processing unit 20 of the fourth comparative example calculates the excess amount of braking force from the start of braking control to time T6. Because time T5 to time T6 is shorter than time T0 to time T5, the excess amount of braking force from time T0 to time T5 has not been sufficiently reduced at the time of the second calculation timing. Therefore, the excess amount of braking force at the second calculation timing is large. The brake control processing unit 20 divides the excess amount of braking force by the previous cycle (i.e., time T5 to time T6) to obtain a current correction value, and corrects the reference deceleration using this current correction value to calculate the deceleration. At this time, because the excess amount of braking force is large and the previous cycle is short, the deceleration command value at the second calculation timing is much smaller (i.e., close to 0) than the deceleration command value at the first calculation timing.

[0111] Next, at the third calculation timing (i.e., time T11), the brake control processor 20 of the fourth comparative example calculates the difference in braking force from the start of braking control to time T11. Because the period from time T6 to time T11 is longer than the period from time T5 to time T6, at the third calculation timing, the total braking force output by the brake device 30 based on the deceleration command value issued during that period is significantly insufficient compared to the total amount of braking force based on the deceleration requested by the brake required deceleration gradient information from the start of braking control to time T11. The brake control processor 20 divides the braking force shortage by the previous period (i.e., time T6 to time T11) to obtain a current correction value, and corrects the reference deceleration using this current correction value to calculate the deceleration. Therefore, the deceleration command values ​​at the three calculation timings are significantly larger than the deceleration command values ​​at the two calculation timings.

[0112] Thus, in the fourth comparative example, when there is a large variation in the cycle between calculation timings, the correction value fluctuates greatly. When the deceleration command value suddenly decreases, as at the second calculation timing (i.e., time T6), the vehicle braking weakens, resulting in so-called brake slippage. On the other hand, when the deceleration command value suddenly increases, as at the third calculation timing (i.e., time T11), the vehicle is suddenly braked, causing the vehicle behavior to become unstable.

[0113] The method of calculating the deceleration command value calculated by the brake control processing unit 20 of the tenth embodiment will be described with reference to the graph of FIG. 19, in comparison with the fourth comparative example.

[0114] In Fig. 19, the deceleration command value calculated by the brake control processing unit 20 of the tenth embodiment is indicated by a thick solid line M. The brake control processing unit 20 of the tenth embodiment also calculates a deceleration command value at each of the calculation timings of times T0 to T5, T6, and T11. Note that in Fig. 19 as well, the brake required deceleration gradient information is indicated by a dashed line A, the deceleration command value calculated by the brake control processing unit 20 of the third comparative example is indicated by a dashed line K, and the deceleration command value calculated by the brake control processing unit 20 of the fourth comparative example is indicated by a solid line L.

[0115] The brake control processor 20 of the tenth embodiment is configured to be able to calculate an upper limit guard value and a lower limit guard value for the correction value. More specifically, when calculating the current correction value at each calculation timing, if the value obtained by dividing the braking force difference amount by the previous cycle falls outside the range between the upper limit guard value and the lower limit guard value, the brake control processor 20 changes the value to fall within that range and sets the current correction value as such. For example, if the value obtained by dividing the braking force difference amount by the previous cycle is greater in absolute value than the upper limit guard value, the brake control processor 20 sets the upper limit guard value as the current correction value. Also, for example, if the value obtained by dividing the braking force difference amount by the previous cycle is smaller in absolute value than the lower limit guard value, the brake control processor 20 sets the lower limit guard value as the current correction value.

[0116] In the tenth embodiment, the upper and lower limit guard values ​​are set as follows. Lower limit guard value = Brake request acceleration gradient x Ideal cycle Upper limit guard value = 0 The ideal period can be the shortest period in design.

[0117] By setting the lower limit guard as described above, it is possible to prevent the corrected deceleration command value from becoming very small compared to the reference deceleration. If the period between time T5 and time T6 in Fig. 19 is taken as an ideal period, it is possible to make the corrected deceleration command value at the current calculation timing (e.g., time T5) ≧ the reference deceleration at the next calculation timing (e.g., time T6).

[0118] The braking control device (i.e., the brake control processing unit 20) of the tenth embodiment described above is configured to be able to calculate an upper guard value and a lower guard value for the correction value. If the value obtained by dividing the braking force difference amount by the previous cycle falls outside the range from the upper guard value to the lower guard value, the correction value calculation unit sets a value in the range from the upper guard value to the lower guard value as the correction value. According to this, even if there is a large fluctuation in the cycle between calculation timings, by limiting the correction value to a value within the range from the upper guard value to the lower guard value, it is possible to prevent a sudden increase or decrease in the deceleration command value, thereby preventing so-called brake slippage due to weak vehicle braking and unstable vehicle behavior due to sudden braking of the vehicle.

[0119] (Eleventh embodiment) An eleventh embodiment will be described. The eleventh embodiment differs from the tenth embodiment in that the method for setting the upper and lower limit guard values ​​is changed, but the rest of the eleventh embodiment is the same as the tenth embodiment, so only the differences from the tenth embodiment will be described.

[0120] A calculation method of the deceleration command value calculated by the brake control processing unit 20 of the eleventh embodiment will be described with reference to the graph in Fig. 20. In Fig. 20, the deceleration command value calculated by the brake control processing unit 20 of the eleventh embodiment is indicated by a thick solid line N. Note that in Fig. 20 as well, the brake required deceleration gradient information is indicated by a dashed line A, the deceleration command value calculated by the brake control processing unit 20 of the third comparative example is indicated by a dashed line K, and the deceleration command value calculated by the brake control processing unit 20 of the fourth comparative example is indicated by a solid line L.

[0121] In the eleventh embodiment, the upper and lower limit guard values ​​are set as follows. Lower limit guard value = Brake request acceleration gradient x Ideal period x Constant In the example of FIG. 20, the constant is set to 4. The lower limit guard is set to the correction value.

[0122] On the other hand, the upper limit guard value is set to the deceleration command value, not the correction value. Specifically, the upper limit guard value is set as follows: the deceleration command value corrected at the current calculation timing≦the deceleration command value corrected at the previous calculation timing.

[0123] In the eleventh embodiment, by setting the lower limit guard as described above, it is possible to deal more appropriately with excess braking force than in the tenth embodiment. However, it is preferable to set the constant to a small value so that the braking force is not insufficient. Furthermore, by setting the upper limit guard as described above, it is possible to prevent the braking force from increasing at the time of calculation from being greater than the previous time, thereby preventing discomfort to the occupants.

[0124] (Other embodiments) In the above embodiments, when calculating the correction value using Equation 4, the braking force difference (i.e., the current total braking force shortage amount) is divided by the previous cycle, but this is not limiting. For example, the braking force difference (i.e., the current total braking force shortage amount) may be divided by an ideal cycle or a fixed value, or may be divided by the average value of the cycles up to that point.

[0125] The present disclosure is not limited to the above-described embodiments and can be modified as appropriate within the scope of the claims. Furthermore, the above-described embodiments and portions thereof are not unrelated to each other and can be combined as appropriate unless the combination is clearly impossible. It goes without saying that, in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless specifically stated as essential or clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of components of the embodiments are mentioned, they are not limited to the specific numbers unless specifically stated as essential or clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shape, positional relationship, etc. of components are mentioned, they are not limited to the shape, positional relationship, etc., unless specifically stated or limited to a specific shape, positional relationship, etc. in principle.

[0126] The controller and the method described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the controller and the method described herein may be implemented by a special-purpose computer configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the controller and the method described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. The memory described above is a non-transitory tangible storage medium. [Explanation of symbols]

[0127] 11 Object selection unit (vehicle-side control device) 12 Deceleration calculation unit (vehicle side control device) 20 Brake control processing unit (braking control device) 30 Brake device

Claims

1. A braking control device that issues a deceleration command value to a brake device (30) calculated at each calculation timing based on brake-requested deceleration gradient information indicating a time transition characteristic of a deceleration of a vehicle requested from a vehicle-side control device (11, 12), a braking control device that calculates the deceleration command value obtained by correcting a reference deceleration as the deceleration required by the brake required deceleration gradient information so as to compensate, from the current calculation timing onwards, for a difference between the total amount of braking force based on the deceleration required by the brake required deceleration gradient information from the start of braking control to the current calculation timing and the total amount of braking force output by the brake device based on the deceleration command value issued from the start of braking control to the current calculation timing.

2. 2. The brake control device according to claim 1, wherein, when a total amount of braking force output by the brake device based on the deceleration command value commanded from the start of braking control to the current calculation timing is smaller than a total amount of braking force based on the deceleration requested by the brake required deceleration gradient information from the start of braking control to the current calculation timing, the deceleration command value is calculated by increasing the reference deceleration at the current calculation timing in accordance with the difference amount.

3. 2. The brake control device according to claim 1, wherein, when a total amount of braking force output by the brake device based on the deceleration command value commanded from the start of braking control to the current calculation timing is greater than a total amount of braking force based on the deceleration requested by the brake required deceleration gradient information from the start of braking control to the current calculation timing, the deceleration command value is calculated by reducing the reference deceleration at the current calculation timing in accordance with the difference amount.

4. a reference deceleration calculation unit (S20) that calculates the reference deceleration as the deceleration required by the brake required deceleration gradient information at each calculation timing; a difference amount calculation unit (S30 to S33) that calculates a difference amount between a total amount of braking force based on the deceleration requested by the brake requested deceleration gradient information from the start of braking control until the current calculation timing and a total amount of braking force output by the brake device based on the deceleration command value commanded from the start of braking control until the current calculation timing; a correction value calculation unit (S40, S41, S42) that calculates a correction value that can compensate for the difference amount calculated by the difference amount calculation unit after the current calculation timing; 4. The braking control device according to claim 1, further comprising: a command value calculation unit (S50, S51) that calculates the deceleration command value by correcting the reference deceleration calculated by the reference deceleration calculation unit at the current calculation timing with the correction value.

5. 5. The brake control device according to claim 4, wherein the correction value calculation unit sets the correction value to a value obtained by dividing the difference calculated by the difference calculation unit by the time of a previous cycle from the previous calculation timing to the current calculation timing.

6. 5. The braking control device according to claim 4, wherein an upper limit guard value and a lower limit guard value of the correction value are stored in advance or are configured to be calculable, and when a value obtained by dividing the difference amount by the time of the previous cycle falls outside the range from the upper limit guard value to the lower limit guard value, a value in the range from the upper limit guard value to the lower limit guard value is set as the correction value.

7. 5. The brake control device according to claim 4, wherein an upper limit guard value and a lower limit guard value of the deceleration command value are stored in advance or are configured to be calculable, and when a value obtained by correcting the reference deceleration so as to compensate for the difference amount at a current calculation timing or later falls outside the range from the upper limit guard value to the lower limit guard value, a value in the range from the upper limit guard value to the lower limit guard value is set as the deceleration command value.

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