Vehicle brake control device

Abstract

To suppress a deviation between actual deceleration and a calculated value in a brake controller that calculates deceleration of a vehicle from a deceleration based on a wheel speed and a G sensor value.SOLUTION: A controller 10 being a brake controller of a vehicle includes a low-pass processing unit 15 for calculating a first filter deceleration by applying low-pass filtering to a deceleration based on a detection signal from a wheel speed sensor 91. The controller 10 includes a high-pass processing unit 16 for calculating a second filter deceleration by applying high-pass filtering to a deceleration based on a detection signal from a longitudinal acceleration sensor 92. The controller 10 includes a third calculation unit 17 for acquiring a deceleration calculation value on the basis of the first filter deceleration and the second filter deceleration. If at least one condition of the acceleration / deceleration of the wheels being smaller than a determination value, and an amount of change in deceleration of the wheels being equal to or smaller than a determination value is established, the low-pass processing unit 15 and the high-pass processing unit 16 make a cutoff frequency high.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a braking control device for a vehicle. [Background technology]

[0002] In a vehicle braking control device, braking force is controlled based on the deceleration of the vehicle. The following two methods are generally known as a method for detecting the deceleration of the vehicle. One is a method for obtaining a wheel reference deceleration, which is the deceleration of the vehicle calculated based on the wheel speed. The other is a method for obtaining a G sensor deceleration, which is the deceleration of the vehicle based on the acceleration acting in the longitudinal direction of the vehicle detected by a longitudinal acceleration sensor.

[0003] Patent Document 1 discloses a method in which low-pass filtering is performed on the wheel reference deceleration and high-pass filtering is performed on the G sensor deceleration, and a deceleration calculation value to be used for control is obtained based on the two decelerations after filtering. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-52964 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the road surface on which the vehicle is traveling changes from an uphill or downhill to a horizontal road surface, the G sensor deceleration may change even though the deceleration of the vehicle does not actually change. In such a case, if the vehicle deceleration calculation value is obtained based on the wheel reference deceleration and the G sensor deceleration as disclosed in Patent Document 1, there is a problem that the deviation between the calculated deceleration value and the actual deceleration of the vehicle becomes large. [Means for solving the problem]

[0006] A vehicle braking control device for solving the above problem includes a first calculation unit that calculates a first deceleration as a deceleration of the vehicle based on a detection signal from a wheel speed sensor, a second calculation unit that calculates a second deceleration as a deceleration of the vehicle based on a detection signal from a longitudinal acceleration sensor, a low-pass processing unit that applies low-pass filter processing to the first deceleration to calculate a first filtered deceleration, a high-pass processing unit that applies high-pass filter processing to the second deceleration to calculate a second filtered deceleration, a third calculation unit that obtains a deceleration calculation value based on the first filtered deceleration and the second filtered deceleration, and a control unit that controls the braking device of the vehicle in accordance with the deceleration calculation value.The gist of the device is that when at least one of the following conditions is satisfied: the acceleration / deceleration of a wheel is smaller than a specified judgment value, and the amount of change per unit time in the deceleration of the wheel is equal to or less than a specified judgment value, the low-pass processing unit and the high-pass processing unit set a cut-off frequency higher when the switching condition is satisfied than when the switching condition is not satisfied.

[0007] When the cutoff frequency in the high-pass filter process is increased, low-frequency noise components are easily removed from the deceleration based on the longitudinal acceleration sensor. Therefore, when the actual deceleration and the deceleration based on the longitudinal acceleration sensor deviate from each other, the high cutoff frequency makes it easier to eliminate the deviation. In other words, the responsiveness of the deceleration calculated with respect to the actual deceleration is improved. However, the detection value from the wheel speed sensor contains high-frequency noise components. In order to remove high-frequency noise components from the deceleration based on the wheel speed sensor, it is preferable to set an extremely small value to the cutoff frequency in the low-pass filter process. Therefore, while the responsiveness is improved when the cutoff frequency is increased, there is a problem that the noise components that cause errors cannot be completely removed from the deceleration based on the wheel speed sensor.

[0008] Therefore, in the above configuration, the cutoff frequency is increased when at least one of the following conditions is satisfied: the acceleration / deceleration of the wheel is smaller than a prescribed judgment value, and the amount of change per unit time in the deceleration of the wheel is equal to or smaller than a prescribed judgment amount. If the acceleration / deceleration of the wheel is smaller than the prescribed judgment value, it can be estimated that the vehicle is not accelerating or decelerating rapidly. Also, if the amount of change per unit time in the deceleration of the wheel is equal to or smaller than the prescribed judgment amount, it can be estimated that the variation in the deceleration of the wheel is small. The cases where the vehicle is not accelerating rapidly, where the vehicle is not decelerating rapidly, and where the variation in the deceleration of the wheel is small are examples of situations where the deceleration based on the wheel speed sensor is not easily affected by noise components. That is, in the above configuration, the cutoff frequency is increased when the deceleration based on the wheel speed sensor is not easily affected by noise components. This makes it possible to improve the responsiveness of the deceleration calculation value while minimizing the influence of noise components on the deceleration based on the wheel speed sensor. The improved responsiveness makes it easier to eliminate the discrepancy between the deceleration calculation value and the actual deceleration of the vehicle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an embodiment of a vehicle braking control device and a vehicle equipped with the same; [Diagram 2] 3 is a flowchart showing a flow of processing executed by the brake control device. [Diagram 3] 5 is a timing chart showing the transition of deceleration when a vehicle moves from a downhill road surface to a level road surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a vehicle braking control device will be described with reference to Figs. 1 shows a control device 10 which is a braking control device for a vehicle, and a vehicle 90 equipped with the control device 10. The control device 10 controls a braking device 20 of the vehicle 90.

[0011] <vehicle> A motorcycle is an example of the vehicle 90. The vehicle 90 is not limited to a motorcycle, and may be, for example, a four-wheeled automobile.

[0012] An example of the braking device 20 is a friction braking device that applies a friction braking force to the wheels. As the friction braking device, for example, a hydraulic braking device can be adopted. The braking device 20 is not limited to a friction braking device, and may be a regenerative braking device that applies a regenerative braking force to the wheels. As the braking device 20, a braking device that can perform cooperative control of the friction braking force and the regenerative braking force by a friction braking device and a regenerative braking device can also be adopted.

[0013] The vehicle 90 is equipped with various sensors. FIG. 1 shows a wheel speed sensor 91 and a longitudinal acceleration sensor 92 as examples of the various sensors. Detection signals from the various sensors are input to the control device 10. The wheel speed sensor 91 can detect the speed of the wheels of the vehicle 90. For example, the wheel speed sensor 91 is composed of a gear-shaped rotor that rotates together with the wheels, and an electromagnetic pickup arranged in close proximity to the teeth of the rotor. The wheel speed sensor 91 is provided on each wheel of the vehicle 90. The longitudinal acceleration sensor 92 can detect the acceleration in the longitudinal direction of the vehicle 90. For example, the longitudinal acceleration sensor 92 is provided on the body of the vehicle 90. An example of a location where the longitudinal acceleration sensor 92 is installed is near the center of the vehicle body in the longitudinal direction.

[0014] Control Device The control device 10 will be described. The control device 10 is composed of a plurality of functional units that realize various functions. Fig. 1 shows an acquisition unit 11, a control unit 12, a first calculation unit 13, a second calculation unit 14, a low-pass processing unit 15, a high-pass processing unit 16, and a third calculation unit 17 as examples of the functional units. Each functional unit can transmit and receive information to and from one another.

[0015] The control device 10 may have any of the following configurations [a] to [c]. [a] It has one or more processors that execute various processes according to a computer program. The processor has a processing device. Examples of the processing device include a CPU, a DSP, and a GPU. The processor has a memory. Examples of the memory include a RAM, a ROM, and a flash memory. The memory stores program codes or instructions configured to cause the processing device to execute the processes. The memory, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. [b] It has one or more hardware circuits that execute various processes. Examples of the hardware circuits include an ASIC (Application Specific Integrated Circuit), a CPLD (Complex Programmable Logic Device), and an FPGA (Field Programmable Gate Array). [c] It has a processor that executes some of the various processes according to a computer program, and a hardware circuit that executes the remaining processes of the various processes.

[0016] Detection signals from various sensors are input to the acquisition unit 11. The acquisition unit 11 can calculate a wheel speed VW as the speed of each wheel based on the detection signal from the wheel speed sensor 91. The acquisition unit 11 can acquire a detection signal from the longitudinal acceleration sensor 92 as G-sensor raw data Gx. The G-sensor raw data Gx indicates the acceleration of the vehicle 90 in the longitudinal direction.

[0017] The control unit 12 can control the braking device 20. The control unit 12 can execute various types of control for adjusting the braking force applied to each wheel. For example, the control unit 12 may execute rear lift suppression control.

[0018] The rear lift suppression control is a control for suppressing the occurrence of rear lift. Rear lift is a phenomenon in which the rear wheels lift off the ground when the deceleration of the vehicle 90 is large and the load on the rear wheels is significantly reduced due to the pitching moment caused by the deceleration of the vehicle 90. The rear lift suppression control suppresses an increase in braking force when the deceleration reaches or exceeds a predetermined value, for example. This makes it possible to suppress the occurrence of rear lift.

[0019] The first calculation unit 13 can calculate a first deceleration Gxw as the deceleration of the vehicle 90. The first calculation unit 13 calculates the first deceleration Gxw by time-differentiating the speed of the vehicle 90. The speed of the vehicle 90 can be calculated based on the wheel speed VW of each wheel calculated by the acquisition unit 11.

[0020] The second calculation unit 14 can calculate the second deceleration Gxg as the deceleration of the vehicle 90. The second calculation unit 14 calculates the second deceleration Gxg based on the G-sensor raw data Gx calculated by the acquisition unit 11. For example, the second calculation unit 14 calculates the second deceleration Gxg by performing pre-processing on the G-sensor raw data Gx. One example of the pre-processing is pitch angle correction for removing a component caused by the inclination of the vehicle 90 from the G-sensor raw data Gx.

[0021] The low-pass processing unit 15 can perform low-pass filtering on the first deceleration Gxw. The low-pass processing unit 15 can perform low-pass filtering on the first deceleration Gxw using a cutoff frequency fc, and calculate the processed value as the first filter deceleration Gxwlp. The first filter deceleration Gxwlp is a value from which frequency components higher than the cutoff frequency fc have been removed. As will be described in detail later, the cutoff frequency fc can be changed.

[0022] The high-pass processing unit 16 can perform high-pass filtering on the second deceleration Gxg. The high-pass processing unit 16 can perform high-pass filtering on the second deceleration Gxg using a cutoff frequency fc, and calculate the processed value as the second filtered deceleration Gxghp. The second filtered deceleration Gxghp is a value from which components of frequencies lower than the cutoff frequency fc have been removed. The cutoff frequency fc can be changed. As an example, the cutoff frequency fc in the high-pass filtering uses a frequency that is the same as the cutoff frequency fc in the low-pass filtering.

[0023] The third calculation unit 17 can calculate the deceleration calculation value Gxf as the deceleration of the vehicle 90. The third calculation unit 17 calculates the deceleration calculation value Gxf based on the first filter deceleration Gxwlp and the second filter deceleration Gxghp. For example, the third calculation unit 17 acquires an average value of the first filter deceleration Gxwlp and the second filter deceleration Gxghp as the deceleration calculation value Gxf. The third calculation unit 17 can also calculate the deceleration calculation value Gxf by adjusting a gain for the first filter deceleration Gxwlp and a gain for the second filter deceleration Gxghp. More specifically, a description will be given using a predetermined coefficient KG. The coefficient KG is set to a value equal to or less than "1". The deceleration calculation value Gxf can be calculated as the sum of the first filter deceleration Gxwlp multiplied by the coefficient KG and the second filter deceleration Gxghp multiplied by (1-KG). When the cutoff frequency fc in the high-pass filtering process and the cutoff frequency fc in the low-pass filtering process are different frequencies, the third calculation unit 17 may adjust the gain.

[0024] The calculated deceleration value Gxf can be used by the control unit 12 to control the braking device 20. The calculated deceleration value Gxf is repeatedly calculated while the vehicle 90 is in operation. The greater the calculated deceleration value Gxf is than "0", the more the vehicle 90 is decelerating. On the other hand, the smaller the calculated deceleration value Gxf is than "0", the more the vehicle 90 is accelerating.

[0025] <Cutoff frequency switching process> The switching process will be described with reference to Fig. 2. The switching process is a process for changing the cutoff frequency fc used when calculating the deceleration calculation value Gxf. The switching process can switch the cutoff frequency fc to a first frequency fc1 or a second frequency fc2. The first frequency fc1 and the second frequency fc2 have a relationship in which the second frequency fc2 is higher than the first frequency fc1.

[0026] An example of the first frequency fc1 is 0.1 Hz. The first frequency fc1 may be a value other than 0.1 Hz, but is preferably 0.5 Hz or less. More preferably, the first frequency fc1 is 0.2 Hz or less.

[0027] An example of the second frequency fc2 is 1 Hz. The second frequency fc2 may be a value other than 1 Hz, but is preferably greater than 0.5 Hz. The second frequency fc2 is preferably equal to or less than 2 Hz.

[0028] The switching process is executed by, for example, the low-pass processing unit 15 and the high-pass processing unit 16. The switching process may be executed by another functional unit in the control device 10. The result of the switching process, which is to select either the first frequency fc1 or the second frequency fc2, may be shared between the functional units. For example, the switching process may be executed by the high-pass processing unit 16, and the result may be shared with the low-pass processing unit 15.

[0029] In the low-pass processing unit 15, the cutoff frequency fc in the low-pass filtering process is changed based on the result of the switching process. In the high-pass processing unit 16, the cutoff frequency fc in the high-pass filtering process is changed based on the result of the switching process.

[0030] In the switching process, a condition for switching between selecting the first frequency fc1 or the second frequency fc2 as the cutoff frequency fc is defined as a switching condition. When the switching condition is not satisfied, the first frequency fc1 is selected. When the switching condition is satisfied, the second frequency fc2 is selected. For example, the switching condition is satisfied when both conditions are satisfied: the acceleration / deceleration of the wheel is smaller than a prescribed judgment value, and the amount of change in the deceleration of the wheel per unit time is equal to or less than the prescribed judgment amount.

[0031] 2 shows the flow of the switching process. This processing routine is repeatedly executed at a predetermined cycle. In the following, as an example, a case where the switching process is executed by the low-pass processing unit 15 and the high-pass processing unit 16 will be described. The low-pass processing unit 15 and the high-pass processing unit 16 are collectively referred to as a filter processing unit.

[0032] When this processing routine is started, first, in step S101, the filter processing unit obtains a deceleration for judgment Gx(w) to be used for judgment. As the deceleration for judgment Gx(w), a deceleration based on the wheel speed VW is used.

[0033] The determination deceleration Gx(w) will be described. For example, the filter processing unit acquires the first deceleration Gxw as the determination deceleration Gx(w). The filter processing unit can also use the first filter deceleration Gxwlp, which is a value obtained by performing low-pass filtering with a cutoff frequency fc set to the second frequency fc2, as the determination deceleration Gx(w). For example, the first filter deceleration Gxwlp, which is a value obtained by performing low-pass filtering with a cutoff frequency fc set to 1 Hz, may be used as the determination deceleration Gx(w). In some cases, it may be better to use a value from which noise components have been removed by low-pass filtering as the determination deceleration Gx(w).

[0034] When the determination deceleration Gx(w) is acquired in the process of step S101, the filter processing unit shifts the process to step S102. In step S102, the filter processing unit determines whether the acceleration / deceleration of the wheel is smaller than a prescribed determination value. For example, when the absolute value of the determination deceleration Gx(w) is smaller than the determination value GTh1, the filter processing unit determines that the acceleration / deceleration of the wheel is smaller than the prescribed determination value. On the other hand, when the absolute value of the determination deceleration Gx(w) is equal to or larger than the determination value GTh1, the filter processing unit determines that the acceleration / deceleration of the wheel is equal to or larger than the prescribed determination value. The determination value GTh1 corresponds to the prescribed determination value. The filter processing unit may determine that the acceleration / deceleration of the wheel is smaller than the prescribed determination value when the state in which the absolute value of the determination deceleration Gx(w) is smaller than the determination value GTh1 continues for a prescribed determination time or more.

[0035] The judgment value GTh1 will be described. The judgment value GTh1 is set to a value that allows estimation that the vehicle 90 is not rapidly decelerating or accelerating if the absolute value of the judgment deceleration Gx(w) is smaller than the judgment value GTh1. The judgment value GTh1 is set to a value calculated in advance by experiments or the like. It is desirable that the judgment value GTh1 be 0.5G or less. It is also desirable that the judgment value GTh1 be 0.1G or more. An example of the judgment value GTh1 is 0.3G.

[0036] In the process of step S102, if the acceleration / deceleration of the wheels is equal to or greater than a specified judgment value, that is, if the absolute value of the judgment deceleration Gx(w) is equal to or greater than the judgment value GTh1 (S102: NO), the filter processing unit transitions to step S105.

[0037] In step S105, the filter processor selects the first frequency fc1 as the cutoff frequency fc. As a result, the first filter deceleration Gxwlp and the second filter deceleration Gxghp are calculated by the cutoff frequency fc set to the first frequency fc1. When the filter processor selects the first frequency fc1 as the cutoff frequency fc, it ends this processing routine.

[0038] On the other hand, in the processing of step S102, if the acceleration / deceleration of the wheels is smaller than the specified judgment value, i.e., if the absolute value of the judgment deceleration Gx(w) is smaller than the judgment value GTh1 (S102: YES), the filter processing unit transitions to step S103.

[0039] In step S103, the filter processor determines whether the amount of change per unit time in the deceleration of the wheel is equal to or less than a prescribed judgment amount. For example, the filter processor obtains the amount of change per unit time in the deceleration of the wheel based on the difference between the previous value of the deceleration for judgment Gx(w) and the current deceleration for judgment Gx(w), and uses the amount of change per unit time for the judgment. Specifically, the filter processor determines whether the absolute value of the amount of change for judgment ΔGx(w) is equal to or less than the judgment amount ΔGTh2, using the difference between the previous value of the deceleration for judgment Gx(w) and the current deceleration for judgment Gx(w). If the absolute value of the amount of change for judgment ΔGx(w) is greater than the judgment amount ΔGTh2, the filter processor determines that the amount of change per unit time in the deceleration of the wheel is greater than the prescribed judgment amount. On the other hand, when the absolute value of the determination amount of change ΔGx(w) is equal to or smaller than the determination amount ΔGTh2, the filter processing unit determines that the amount of change per unit time in the deceleration of the wheel is equal to or smaller than a prescribed determination amount. The determination amount ΔGTh2 corresponds to the prescribed determination amount. The filter processing unit may determine that the amount of change per unit time in the deceleration of the wheel is equal to or smaller than the prescribed determination amount when the state in which the absolute value of the determination amount of change ΔGx(w) is equal to or smaller than the determination amount ΔGTh2 continues for a prescribed determination time or more.

[0040] The judgment amount ΔGTh2 will be described. The judgment amount ΔGTh2 is set to a value that can be used to judge that the variation in deceleration of the wheel is small if the absolute value of the judgment change amount ΔGx(w) is equal to or less than the judgment amount ΔGTh2. The judgment amount ΔGTh2 is set to a value calculated in advance by experiments or the like. It is desirable that the judgment amount ΔGTh2 is equal to or less than 0.02G / 6ms. An example of the judgment amount ΔGTh2 is 0.002G / 6ms.

[0041] In the process of step S103, if the absolute value of the judgment change amount ΔGx(w) is greater than the judgment amount ΔGTh2 (S103: NO), the filter processing unit shifts the process to step S105. That is, if the change amount per unit time in the deceleration of the wheel is greater than a specified judgment amount, the filter processing unit shifts the process to step S105. When the filter processing unit selects the first frequency fc1 as the cutoff frequency fc in step S105, it ends this processing routine.

[0042] On the other hand, in the process of step S103, if the absolute value of the judgment change amount ΔGx(w) is equal to or smaller than the judgment amount ΔGTh2 (S103: YES), the filter processing unit shifts the process to step S104. That is, if the change amount per unit time in the wheel deceleration is equal to or smaller than the specified judgment amount, the filter processing unit shifts the process to step S104.

[0043] In step S104, the filter processor selects the second frequency fc2 as the cutoff frequency fc. As a result, the first filter deceleration Gxwlp and the second filter deceleration Gxghp are calculated by the cutoff frequency fc set to the second frequency fc2 higher than the first frequency fc1. When the filter processor selects the second frequency fc2 as the cutoff frequency fc, it ends this processing routine.

[0044] <Action and Effects> The operation and effects of this embodiment will be described. According to the control device 10, when the absolute value of the deceleration for judgment Gx(w) is equal to or greater than the judgment value GTh1 (S102: NO), the first frequency fc1 is selected as the cutoff frequency fc (S105). Also, when the absolute value of the change amount for judgment ΔGx(w) is greater than the judgment amount ΔGTh2 (S103: NO), the first frequency fc1 is selected as the cutoff frequency fc (S105). On the other hand, when the absolute value of the deceleration for judgment Gx(w) is smaller than the judgment value GTh1 (S102: YES) and the absolute value of the change amount for judgment ΔGx(w) is equal to or less than the judgment amount ΔGTh2 (S103: YES), the second frequency fc2 is selected as the cutoff frequency fc (S104). That is, according to the control device 10, when the switching condition is satisfied, the cutoff frequency fc is set higher than when the switching condition is not satisfied.

[0045] When the cutoff frequency fc in the high-pass filter process is increased, low-frequency noise components are easily removed from the second deceleration Gxg based on the longitudinal acceleration sensor 92. That is, the second filter deceleration Gxghp from which low-frequency noise components are removed is easily calculated. For this reason, when the actual deceleration of the vehicle 90 and the G-sensor raw data Gx diverge, the divergence is easily eliminated if the cutoff frequency fc is high. In other words, the responsiveness of the deceleration calculation value Gxf to the actual deceleration is improved. However, the detection value from the wheel speed sensor 91 contains high-frequency noise components. The high-frequency noise components include, for example, noise components caused by the eccentricity of the rotor. That is, the high-frequency noise components also include periodic noise components synchronized with the period of one rotation of the wheel. In order to remove high-frequency noise components from the first deceleration Gxw, which is the deceleration based on the wheel speed sensor 91, it is preferable to set an extremely small value to the cutoff frequency fc in the low-pass filter process. Therefore, while increasing the cutoff frequency fc improves responsiveness, there is a problem in that noise components that cause errors cannot be completely removed from the first deceleration Gxw.

[0046] In this regard, according to the control device 10, when the switching condition is satisfied, the cutoff frequency fc is increased. If the absolute value of the deceleration for judgment Gx(w) is smaller than the judgment value GTh1, that is, the acceleration / deceleration of the wheel is smaller than a prescribed judgment value, it can be estimated that the vehicle 90 is not accelerating or decelerating suddenly. If the absolute value of the change amount for judgment ΔGx(w) is equal to or smaller than the judgment amount ΔGTh2, that is, the change amount per unit time in the deceleration of the wheel is equal to or smaller than a prescribed judgment amount, it can be estimated that the fluctuation in the deceleration of the wheel is small. For example, when the vehicle 90 is traveling at a constant speed on a smooth road surface, the fluctuation in the deceleration of the wheel is small. The fluctuation in the deceleration of the wheel is likely to be small in a situation where there is little disturbance, such as the condition of the road surface. On the other hand, when the road surface is rough, the deceleration of the wheel may fluctuate greatly even if the speed of the vehicle 90 is close to "0". Examples of situations in which the first deceleration Gxw is less susceptible to noise components include when the vehicle 90 is not accelerating suddenly, when the vehicle 90 is not decelerating suddenly, and when the variation in the deceleration of the wheels is small. Therefore, when both conditions are satisfied, that is, the acceleration / deceleration of the wheels is smaller than a prescribed judgment value, and the amount of change per unit time in the deceleration of the wheels is equal to or less than the prescribed judgment value, the first deceleration Gxw is less susceptible to noise components. That is, in the control device 10, if the first deceleration Gxw is less susceptible to noise components, the cutoff frequency fc is set to be high. This makes it possible to improve the responsiveness of the deceleration calculation value Gxf while minimizing the influence of the noise components on the first deceleration Gxw. The improved responsiveness makes it easier to eliminate the discrepancy between the deceleration calculation value Gxf and the actual deceleration of the vehicle 90.

[0047] The effect of changing the cutoff frequency fc will now be specifically described. If the cutoff frequency fc in the low-pass filter process is set to 0.5 Hz, noise components may not be removed from the first deceleration Gxw. Therefore, the first frequency fc1 selected in a situation where the first deceleration Gxw is easily affected by noise components is preferably 0.5 Hz or less. If the cutoff frequency fc in the high-pass filter process is set to 0.5 Hz, the G sensor raw data Gx may be easily affected for a long time by deviations, and responsiveness may decrease. Therefore, the second frequency fc2 is preferably higher than 0.5 Hz.

[0048] If the cutoff frequency fc in the low-pass filter process is set higher than 2 Hz, the noise components contained in the first filter deceleration Gxwlp may increase even in a situation where the first deceleration Gxw is not easily affected by noise components. For this reason, the second frequency fc2 selected in a situation where the first deceleration Gxw is not easily affected by noise components is preferably 2 Hz or less.

[0049] In a situation where the first deceleration Gxw is easily affected by noise components, if the cutoff frequency fc in the low-pass filter processing is higher than 0.2 Hz, the noise components contained in the first filter deceleration Gxwlp may increase. For this reason, it is preferable that the first frequency fc1 is 0.2 Hz or less.

[0050] If the cutoff frequency fc in the low-pass filter process is set to 0.1 Hz, the first filtered deceleration Gxwlp can be calculated with more noise components removed. For example, even if the wheels slip, the effect of the slip is less likely to be reflected in the deceleration calculation value Gxf. For this reason, it is more preferable that the first frequency fc1 is 0.1 Hz.

[0051] If the cutoff frequency fc in the low-pass filter process is set to 1 Hz, for example, even if the rotor of the wheel speed sensor 91 is eccentric, fluctuations in the wheel speed VW due to the eccentricity are less likely to be reflected in the deceleration calculation value Gxf. For this reason, it is more preferable that the second frequency fc2 is 1 Hz.

[0052] Next, an example of the deceleration calculation value Gxf calculated by the control device 10 will be described with reference to FIG. 3. FIG. 3 shows the transition of the deceleration calculation value Gxf and the G-sensor raw data Gx when the vehicle 90 moves from a downhill to a horizontal road surface. The actual deceleration of the vehicle 90 in the range shown in FIG. 3 does not change from "0". FIG. 3 shows the time when the vehicle passes between a downhill and a horizontal road surface as timing t1. That is, timing t1 indicates the time when the road surface gradient changes. The deceleration shown in FIG. 3 is a value that indicates that the vehicle 90 is decelerating as it is larger than "0".

[0053] 3, the deceleration calculation value Gxf calculated when the second frequency fc2 is selected as the cutoff frequency fc is shown by a solid line. As a comparative example, the deceleration calculation value Gxf calculated when the first frequency fc1 is selected is shown by a two-dot chain line. Furthermore, the G-sensor raw data Gx is shown by a dashed line.

[0054] As shown in FIG. 3, the G-sensor raw data Gx fluctuates toward a smaller deceleration even though the actual deceleration does not change near the timing t1 when the road surface gradient changes. As a result, the deceleration calculation value Gxf affected by the fluctuation of the G-sensor raw data Gx deviates from the actual deceleration "0". At this time, if the first frequency fc1 is selected as the cutoff frequency fc, the period during which the deceleration deviates from the actual deceleration tends to become long, as shown by the two-dot chain line in the comparative example. In contrast, if the second frequency fc2 is selected as the cutoff frequency fc, the deviation can be eliminated more quickly, as shown by the solid line, than in the comparative example shown by the two-dot chain line. In this way, according to the control device 10, the responsiveness of the deceleration calculation value Gxf can be improved by increasing the cutoff frequency fc.

[0055] In FIG. 3, a case where the vehicle 90 moves from a downhill to a horizontal road surface has been described as an example. Not limited to this, when the road surface gradient of the road surface on which the vehicle 90 runs changes, the G sensor raw data Gx may fluctuate even though the actual deceleration does not change. For example, when the vehicle 90 moves from an uphill to a horizontal road surface, the G sensor raw data Gx may fluctuate in a direction to increase the deceleration even though the actual deceleration does not change. Even in such a case, the control device 10 can increase the cutoff frequency fc if the switching condition is satisfied. This can improve the responsiveness of the deceleration calculation value Gxf.

[0056] Unlike the example described using FIG. 3, the deceleration based on the detection signal from the wheel speed sensor 91 may vary even if the actual deceleration does not change. For example, when the posture of the vehicle body of the vehicle 90, which is a motorcycle, changes from a banked state to an upright state, the first deceleration Gxw may vary even if the actual deceleration does not change. This variation is due to a change in the distance between the center of the wheel and the ground surface of the wheel before and after the posture of the vehicle body changes. In this way, when the first deceleration Gxw varies even if the actual deceleration does not change, the deceleration calculation value Gxf deviates from the actual deceleration. Here, according to the control device 10, when the amount of change in the deceleration in the wheel is large, the switching condition is not established. For this reason, the first frequency fc1 is selected as the cutoff frequency fc. That is, since the cutoff frequency fc is lowered, the noise components included in the first deceleration Gxw are less likely to be reflected in the deceleration calculation value Gxf. This makes it possible to reduce the influence of the first deceleration Gxw varying even if the actual deceleration does not change.

[0057] As described above, the control device 10 can suppress the deviation between the deceleration calculation value Gxf and the actual deceleration of the vehicle 90. Therefore, the braking force control using the deceleration calculation value Gxf can be performed with high accuracy. For example, deviation in the start timing of the control can be suppressed. As one example, when the control unit 12 of the control device 10 executes the rear lift suppression control, the deceleration calculation value Gxf can be used. This reduces the influence of factors that cause deviation in the calculated deceleration value, such as a change in road surface gradient before deceleration and noise to the wheel speed sensor 91 during braking, and suppresses deviation in the start timing of the rear lift suppression control.

[0058] (Example of change) This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that they are not technically inconsistent.

[0059] The order of the processing in step S102 and the processing in step S103 may be reversed. In this case, the processing proceeds to step S103 after step S101. If the processing in step S103 is judged to be positive, the processing proceeds to step S102. If the processing in step S102 is judged to be positive, the processing proceeds to step S104.

[0060] In the above embodiment, the switching condition is satisfied when both conditions are satisfied: the wheel acceleration / deceleration is smaller than a prescribed judgment value, and the amount of change in the wheel deceleration per unit time is equal to or less than a prescribed judgment amount. Alternatively, the switching condition may be satisfied when at least one of the conditions is satisfied: the wheel acceleration / deceleration is smaller than a prescribed judgment value, and the amount of change in the wheel deceleration per unit time is equal to or less than a prescribed judgment amount.

[0061] For example, the switching condition may be satisfied when at least one of the following conditions is satisfied: the absolute value of the deceleration for judgment Gx(w) is smaller than the judgment value GTh1, and the absolute value of the amount of change for judgment ΔGx(w) is equal to or smaller than the judgment amount ΔGTh2. Specifically, the second frequency fc2 may be selected when the determination in step S102 is affirmative. Even when the determination in step S102 is negative, the second frequency fc2 may be selected as long as the absolute value of the amount of change for judgment ΔGx(w) is equal to or smaller than the judgment amount ΔGTh2. Alternatively, either one of the processes in steps S102 and S103 may be omitted.

[0062] The switching conditions may include other conditions in addition to the wheel acceleration / deceleration being smaller than a specified judgment value and the amount of change in the wheel deceleration per unit time being equal to or less than the specified judgment value.

[0063] In the above embodiment, an example has been shown in which the average value of the first filter deceleration Gxwlp and the second filter deceleration Gxghp is calculated as the deceleration calculated value Gxf. The third calculation unit 17 may calculate the sum of the first filter deceleration Gxwlp and the second filter deceleration Gxghp as the deceleration calculated value Gxf. The value of the deceleration calculated value Gxf obtained by simply adding the first filter deceleration Gxwlp and the second filter deceleration Gxghp is calculated as a value equivalent to twice the actual deceleration of the vehicle. [Explanation of symbols]

[0064] 10...Control device 11…Acquisition part 12...Control section 13...First calculation section 14...Second calculation section 15...Low pass processing section 16...High-pass processing section 17…Third calculation section 20…braking device 90…Vehicle 91...Wheel speed sensor 92...Front and rear acceleration sensor

Claims

1. A vehicle braking control device that controls a braking device provided in a vehicle, comprising: a first calculation unit that calculates a first deceleration as a deceleration of the vehicle based on a detection signal from a wheel speed sensor; a second calculation unit that calculates a second deceleration as a deceleration of the vehicle based on a detection signal from a longitudinal acceleration sensor; a low-pass processing unit that calculates a first filtered deceleration by performing low-pass filtering on the first deceleration; a high-pass processing unit that performs high-pass filtering on the second deceleration to calculate a second filtered deceleration; a third calculation unit that obtains a deceleration calculation value based on the first filter deceleration and the second filter deceleration; a control unit that controls the braking device in accordance with the deceleration calculation value, The switching condition is determined to be satisfied when at least one of the following conditions is satisfied: the acceleration / deceleration of the wheel is smaller than a prescribed judgment value; and the amount of change in the deceleration of the wheel per unit time is equal to or smaller than a prescribed judgment value. When the switching condition is satisfied, the low-pass processing section and the high-pass processing section set a cut-off frequency higher than when the switching condition is not satisfied. A vehicle braking control device.

2. The cutoff frequency when the switching condition is not satisfied is defined as a first frequency, and the cutoff frequency when the switching condition is satisfied is defined as a second frequency, the first frequency is less than or equal to 0.5 Hz; The second frequency is greater than 0.5 Hz. The vehicle brake control device according to claim 1.

3. The second frequency is less than or equal to 2 Hz. The vehicle brake control device according to claim 2.

4. The first frequency is less than or equal to 0.2 Hz.

4. A vehicle brake control device according to claim 2 or 3.

5. the first frequency is 0.1 Hz; The second frequency is 1 Hz. The vehicle brake control device according to claim 2.

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