Control device and control method

Abstract

To enhance the reliability of preventing a vehicle from sliding down.SOLUTION: A control device 17 comprises a control unit that executes braking force increase control to automatically increase a braking force of a vehicle 10. The control unit is configured to: perform a first process that compares the braking force with a threshold value during a stationary period of the vehicle 10; upon determining that the braking force is below the threshold value, execute the braking force increase control; and upon detecting that the vehicle 10 is sliding down despite the braking force being increased by the first process, executes a second process that further executes the braking force increase control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device and a control method. [Background technology]

[0002] When a vehicle is stopped on a slope, gravity acting on the vehicle may cause the vehicle to roll downhill. Therefore, as disclosed in Patent Document 1, for example, a technology has been proposed that automatically controls the braking force of the vehicle while the vehicle is stopped to prevent the vehicle from rolling downhill. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-032794 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, although several techniques have been proposed for preventing a vehicle from sliding down, new proposals are desired for improving the reliability of preventing a vehicle from sliding down.

[0005] In view of the above, an object of the present invention is to provide a control device and a control method that can improve the reliability of preventing a vehicle from sliding downhill. [Means for solving the problem]

[0006] In order to solve the above problem, the control device includes a control unit that executes braking force increase control to automatically increase the braking force of the vehicle, and the control unit performs a first process that compares the braking force with a threshold value while the vehicle is stopped, and executes braking force increase control if the braking force is equal to or less than the threshold value, and executes a second process that further executes braking force increase control if it detects that the vehicle is rolling down despite the braking force being increased by the first process.

[0007] In order to solve the above problem, the control method is a vehicle control method in which a control unit of a control device performs braking force increase control to automatically increase the braking force of the vehicle, and the control unit performs a first process of comparing the braking force with a threshold value while the vehicle is stopped and performing braking force increase control if the braking force is equal to or less than the threshold value, and a second process of further performing braking force increase control if it detects that the vehicle is rolling down despite the braking force being increased by the first process. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve the reliability of preventing a vehicle from sliding downhill. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a general configuration of a vehicle according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram showing a general configuration of a brake system for a vehicle according to an embodiment of the present invention; [Figure 3] FIG. 2 is a block diagram showing an example of a functional configuration of a control device according to an embodiment of the present invention. [Figure 4] 4 is a flowchart illustrating an example of a flow of processing performed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0011] <Vehicle configuration> The configuration of a vehicle 10 according to an embodiment of the present invention will be described with reference to FIGS.

[0012] 1 is a schematic diagram showing the general configuration of a vehicle 10. As shown in FIG. 1, the vehicle 10 includes a steering mechanism 11, a drive source 12, a hydraulic control unit 13, a plurality of ambient environment sensors 14, a plurality of wheel speed sensors 15, an inertial measurement unit (IMU) 16, and a control device 17.

[0013] The steering mechanism 11 is a mechanism that changes the steering angle of the vehicle 10. The steering angle of the vehicle 10 means the turning angle of the tires of the vehicle 10. The steering mechanism 11 includes a steering wheel 11a. The driver of the vehicle 10 can change the steering angle by performing a steering operation using the steering wheel 11a.

[0014] The drive source 12 outputs a drive force that is transmitted to the drive wheels of the vehicle 10. Examples of the drive source 12 include an engine and an electric motor.

[0015] The hydraulic pressure control unit 13 controls the braking force of the vehicle 10. The hydraulic pressure control unit 13 controls the braking force applied to the wheels by controlling the wheel cylinder pressure, which is the hydraulic pressure of the brake fluid in the wheel cylinder. Details of the hydraulic pressure control unit 13 will be described later.

[0016] The ambient environment sensors 14 detect ambient environment information relating to the environment around the vehicle 10. In the example of FIG. 1 , four ambient environment sensors 14 are provided at the left front, right front, left rear, and right rear of the vehicle 10, respectively. The left front ambient environment sensor 14 detects ambient environment information on the left front of the vehicle 10. The right front ambient environment sensor 14 detects ambient environment information on the right front of the vehicle 10. The left rear ambient environment sensor 14 detects ambient environment information on the left rear of the vehicle 10. The right rear ambient environment sensor 14 detects ambient environment information on the right rear of the vehicle 10.

[0017] The ambient environment information detected by the ambient environment sensor 14 may be information related to the distance or direction to an object located around the vehicle 10 (e.g., relative position, relative distance, relative speed, relative acceleration, etc.), or may be characteristics of the object located around the vehicle 10 (e.g., type of object, shape of the object itself, markings on the object, etc.). The ambient environment sensor 14 may be, for example, a radar, a lidar sensor, an ultrasonic sensor, etc.

[0018] The wheel speed sensor 15 is provided on each wheel and detects the wheel speed of each wheel.

[0019] The inertial measurement unit 16 includes a three-axis gyro sensor and a three-directional acceleration sensor, and detects the angular velocity and acceleration of the vehicle 10. Note that the inertial measurement unit 16 may include only a portion of the three-axis gyro sensor and the three-directional acceleration sensor.

[0020] The control device 17 controls the operation of the vehicle 10. The control device 17 includes a CPU (Central Processing Unit) which is an arithmetic processing device, a ROM (Read Only Memory) which is a storage element that stores programs used by the CPU, calculation parameters, etc., and a RAM (Random Access Memory) which is a storage element that temporarily stores parameters, etc. that change as appropriate during execution of the CPU. Details of the control device 17 will be described later.

[0021] Fig. 2 is a schematic diagram showing the general configuration of a brake system 20 of a vehicle 10. The brake system 20 is mounted on the vehicle 10 and controls the braking force acting on the vehicle 10. As shown in Fig. 2, the brake system 20 includes a hydraulic control unit 13, a brake pedal 21, a brake booster 22, a master cylinder 23, a reservoir 24, wheel cylinders 25, and wheels 26.

[0022] The vehicle 10 has, for example, four wheels 26. The brake system 20 controls the braking force acting on each wheel 26 by controlling the hydraulic pressure (i.e., wheel cylinder pressure) of the wheel cylinders 25 provided in each of these wheels 26. In FIG. 2, for ease of understanding, only the parts related to two of the four wheels 26 (e.g., the left front wheel and the right rear wheel) are shown, and the parts related to the other two wheels 26 (e.g., the right front wheel and the left rear wheel) are not shown. Note that the number of wheels 26 may be other than four.

[0023] The brake pedal 21 is used by the driver to apply the brakes. When applying the brakes, the driver depresses the brake pedal 21. The booster 22 is connected to the brake pedal 21 and works in conjunction with the brake pedal 21 to amplify the force applied to the brake pedal 21. Specifically, the booster 22 incorporates a piston that reciprocates in conjunction with the brake pedal 21 and is connected to a master cylinder 23. As the piston moves in response to the brake application, the master cylinder pressure, which is the hydraulic pressure in the master cylinder 23, is increased. In this way, the booster 22 can generate master cylinder pressure in accordance with the amount of brake application. The reservoir 24 is attached to the master cylinder 23 and stores brake fluid.

[0024] The hydraulic pressure control unit 13 includes a base 13a in which a flow path for brake fluid is formed. The master cylinder 23 and each wheel cylinder 25 are connected to the base 13a of the hydraulic pressure control unit 13. When the wheel cylinder pressure, which is the hydraulic pressure in the wheel cylinder 25, increases, the brake pads (not shown) operate to press against the brake discs (not shown), thereby applying a braking force corresponding to the wheel cylinder pressure to the wheels 26.

[0025] The base body 13a of the hydraulic control unit 13 is formed with brake fluid flow paths, including a main flow path 31, a sub-flow path 32, and a supply flow path 33. The main flow path 31 distributes the brake fluid in the master cylinder 23 to the wheel cylinders 25. The sub-flow path 32 releases the brake fluid in the wheel cylinders 25. The supply flow path 33 supplies the brake fluid in the master cylinder 23 to the sub-flow path 32.

[0026] In addition, the base 13a of the hydraulic control unit 13 is provided with components for controlling the braking force generated on each wheel 26, including an inlet valve (EV) 41, a release valve (AV) 42, a first valve (USV) 43, a second valve (HSV) 44, an accumulator 45, a pump 46, and a motor 47.

[0027] The main flow path 31 connects the master cylinder 23 and the wheel cylinders 25. The main flow path 31 includes one first main flow path 31a and two second main flow paths 31b. The first main flow path 31a is connected to the master cylinder 23. The two second main flow paths 31b branch off from the first main flow path 31a and are connected to the wheel cylinders 25, respectively. A first valve 43 is provided in the first main flow path 31a. An inlet valve 41 is provided in the second main flow path 31b.

[0028] The sub-path 32 communicates the wheel cylinder 25 side of the main path 31 relative to the inlet valve 41 with the master cylinder 23 side of the main path 31 relative to the inlet valve 41 and the wheel cylinder 25 side of the first valve 43. The sub-path 32 includes two first sub-paths 32a and one second sub-path 32b. Each first sub-path 32a is connected to the wheel cylinder 25 side of the main path 31 relative to the inlet valve 41. The second sub-path 32b connects the junction of the two first sub-paths 32a with the master cylinder 23 side of the main path 31 relative to the inlet valve 41 and the wheel cylinder 25 side of the first valve 43. A release valve 42 is provided in the first sub-path 32a. An accumulator 45 and a pump 46 are provided in the second sub-path 32b, in this order from the first sub-path 32a side.

[0029] The pump 46 is driven by the motor 47 and sucks brake fluid from the first sub-channel 32a and discharges it to the main channel 31. The pump 46 is a reciprocating plunger pump. Specifically, the plunger of the pump 46 is intermittently pressed by an eccentric cam provided on the output shaft of the motor 47, thereby causing the pump 46 to pump and deliver brake fluid.

[0030] The supply flow path 33 communicates the master cylinder 23 side of the first valve 43 in the main flow path 31 with the suction side of the pump 46 in the sub-flow path 32. A second valve 44 is provided in the supply flow path 33.

[0031] The inlet valve 41 is, for example, a solenoid valve that is open in a de-energized state and closed in a powered state. The release valve 42 is, for example, a solenoid valve that is closed in a de-energized state and open in a powered state. The first valve 43 is, for example, a solenoid valve that is open in a de-energized state and closed in a powered state. The second valve 44 is, for example, a solenoid valve that is closed in a de-energized state and open in a powered state. By controlling the operation of these valves and the motor 47, the braking force acting on each wheel 26 is controlled.

[0032] The hydraulic control unit 13 is provided with wheel cylinder pressure sensors 48. The wheel cylinder pressure sensors 48 are provided for the respective wheel cylinders 25 and detect the hydraulic pressure (i.e., wheel cylinder pressure) of the respective wheel cylinders 25. The wheel cylinder pressure sensors 48 detect, for example, the hydraulic pressure near the confluence of the first sub-path 32a and the second main path 31b as the wheel cylinder pressure.

[0033] For example, during normal operation when antilock brake control (described later) or the like is not being executed, inlet valve 41 is open, release valve 42 is closed, first valve 43 is open, and second valve 44 is closed. This allows brake fluid to flow from master cylinder 23 to wheel cylinders 25 only through main flow path 31, without passing through sub-flow path 32 and supply flow path 33. When brake pedal 21 is depressed in this state, the master cylinder pressure is increased, which in turn increases wheel cylinder pressure, thereby applying braking force to wheels 26.

[0034] Furthermore, for example, when anti-lock brake control, which is a control for preventing the wheels 26 from locking, is executed, first, the inlet valve 41 is closed, the release valve 42 is opened, the first valve 43 is opened, and the second valve 44 is closed. This stops the flow of brake fluid between the main flow path 31 and the wheel cylinders 25, allowing brake fluid to flow from the wheel cylinders 25 to the secondary flow path 32. Therefore, brake fluid flows from the wheel cylinders 25 to the accumulator 45, reducing the wheel cylinder pressure and the braking force applied to the wheels 26. The brake fluid that has flowed into the accumulator 45 is returned to the main flow path 31 via the secondary flow path 32 by driving the pump 46.

[0035] Then, from the above state, both the inlet valve 41 and the release valve 42 are closed, stopping the flow of brake fluid between the main flow path 31 and the sub-flow path 32 and the wheel cylinders 25, maintaining the wheel cylinder pressure and maintaining the braking force applied to the wheels 26. Thereafter, the inlet valve 41 is opened and the release valve 42 is closed, restarting the flow of brake fluid between the main flow path 31 and the wheel cylinders 25, increasing the wheel cylinder pressure and increasing the braking force applied to the wheels 26.

[0036] Here, the hydraulic control unit 13 can also automatically increase the wheel cylinder pressure without requiring a brake operation. For example, when automatically increasing the wheel cylinder pressure without requiring a brake operation, the inlet valve 41 is opened, the release valve 42 is closed, the first valve 43 is closed, and the second valve 44 is opened. This allows brake fluid to flow from the master cylinder 23 to the wheel cylinder 25 via the supply flow path 33 and the sub-flow path 32. In this state, the pump 46 is driven to increase the wheel cylinder pressure, generating a braking force that brakes the wheel 26.

[0037] 3 is a block diagram showing an example of the functional configuration of control device 17. Control device 17 may be, for example, a single device or may be divided into multiple devices. When control device 17 is divided into multiple devices, the various functions described below are shared among the multiple devices, so that, for example, some functions of control unit 17b described below and other functions may be shared by different devices.

[0038] As shown in FIG. 3, the control device 17 includes, for example, an acquisition unit 17a and a control unit 17b.

[0039] The acquisition unit 17a acquires information from each device in the vehicle 10. For example, the acquisition unit 17a acquires information from the ambient environment sensor 14, the wheel speed sensor 15, the inertial measurement unit 16, and the wheel cylinder pressure sensor 48. In this specification, the acquisition of information may include the extraction or generation (e.g., calculation) of information.

[0040] The control unit 17b controls the operation of each device in the vehicle 10. For example, the control unit 17b controls the operation of the steering mechanism 11, the drive source 12, and the hydraulic control unit 13.

[0041] The control unit 17b can perform various controls to automatically control the running of the vehicle 10 by taking over part or all of the driving operation by the driver, for example, by controlling the steering mechanism 11, the drive source 12, and the hydraulic control unit 13. For example, such controls include adaptive cruise control.

[0042] In adaptive cruise control, control unit 17b automatically controls the speed of vehicle 10 so that vehicle 10 follows a preceding vehicle. For example, control unit 17b identifies the inter-vehicle distance between vehicle 10 and the preceding vehicle using the detection results of ambient environment sensor 14, and automatically controls the speed of vehicle 10 so that the inter-vehicle distance is maintained at a target distance. In controlling the speed of vehicle 10, control unit 17b controls the operation of drive source 12 to control the driving force acting on vehicle 10, and controls the operation of hydraulic control unit 13 to control the braking force acting on vehicle 10, for example.

[0043] Note that the control unit 17b may automatically control the steering angle of the vehicle 10 by controlling the operation of the steering mechanism 11 in addition to or instead of the adaptive cruise control.

[0044] <Control device operation> The operation of the control device 17 according to the embodiment of the present invention will be described with reference to FIG.

[0045] As described above, the control unit 17b of the control device 17 can execute adaptive cruise control. In adaptive cruise control, the control unit 17b automatically controls the speed of the vehicle 10 so that the inter-vehicle distance between the vehicle 10 and a preceding vehicle is maintained at a target distance. Therefore, in adaptive cruise control, the speed of the vehicle 10 is controlled according to the behavior of the preceding vehicle. For example, if the preceding vehicle decelerates and stops, the control unit 17b automatically decelerates and stops the vehicle 10. Also, for example, if the stopped preceding vehicle starts moving, the control unit 17b automatically accelerates and starts the vehicle 10.

[0046] As described above, with adaptive cruise control, most of the driving operations by the driver are left to the control device 17, even when stopping and starting the vehicle 10. However, when the vehicle 10 is stopped on a slope, the vehicle 10 may slide down due to gravity acting on the vehicle 10. The slide down of the vehicle 10 refers to a phenomenon in which the vehicle 10 moves vertically downward along the road surface due to gravity. Here, the control unit 17b can execute braking force increase control to automatically increase the braking force of the vehicle 10 as control to suppress the vehicle 10 from sliding down.

[0047] For example, during braking force increase control, control unit 17b controls hydraulic control unit 13 to a state in which inlet valve 41 is open, release valve 42 is closed, first valve 43 is closed, and second valve 44 is open. This allows brake fluid to flow from master cylinder 23 to wheel cylinder 25 via supply flow path 33 and sub-flow path 32. In this state, control unit 17b uses electric power to operate motor 47, thereby driving pump 46. This automatically increases the wheel cylinder pressure, and the braking force of vehicle 10 is automatically increased.

[0048] In this embodiment, by improving the processing by the control unit 17b using braking force increase control, it is possible to improve the reliability of suppressing the vehicle 10 from rolling downhill. An example of such processing performed by the control device 17 will be described in detail below.

[0049] Fig. 4 is a flowchart showing an example of the flow of processing performed by the control device 17. Step S101 in Fig. 4 corresponds to the start of the processing flow shown in Fig. 4. Step S110 in Fig. 4 corresponds to the end of the processing flow shown in Fig. 4.

[0050] The process flow shown in Fig. 4 starts, for example, while adaptive cruise control is being executed. If the process flow shown in Fig. 4 ends while adaptive cruise control is being executed, the process flow shown in Fig. 4 is resumed after a predetermined time interval.

[0051] As will be described later, the processing from step S103 onwards in the processing flow shown in Fig. 4 is performed while the vehicle 10 is stopped. Specifically, as will be described later, the processing from step S104 onwards in the processing flow shown in Fig. 4 is repeated while the vehicle 10 is stopped. However, as will be described later, if the vehicle 10 starts moving while the processing from step S103 onwards is being executed, the processing flow shown in Fig. 4 ends.

[0052] When the processing flow shown in FIG. 4 starts, in step S102, the control unit 17b determines whether or not the execution conditions for braking force maintenance control are satisfied.

[0053] Braking force maintenance control is control that automatically maintains the braking force of the vehicle 10. Basically, the control unit 17b executes the braking force maintenance control when the vehicle 10 is stopped. Specifically, the control unit 17b executes the braking force maintenance control when the vehicle 10 is stopped in a state where it can start moving. This maintains the braking force of the vehicle 10, and suppresses the vehicle 10 from rolling downhill.

[0054] For example, in braking force maintenance control, control unit 17b controls hydraulic pressure control unit 13 to close all of the electromagnetic valves, namely, inlet valve 41, release valve 42, first valve 43, and second valve 44. This stops the flow of brake fluid between main flow path 31 and sub-flow path 32 and wheel cylinder 25, maintains wheel cylinder pressure, and maintains the braking force applied to wheel 26.

[0055] As will be described later, the control unit 17b executes the braking force maintenance control when the execution conditions for the braking force maintenance control of step S102 are satisfied. Examples of the execution conditions for the braking force maintenance control of step S102 include a condition that the speed of the vehicle 10 is below a speed threshold that is a predetermined value close to 0 km / h, a condition that the yaw rate of the vehicle 10 is below a yaw rate threshold that is a predetermined value close to 0 deg / s, a condition that the drive source 12 is in a standby state in a state where it can output drive force, and a condition that the current braking force of the vehicle 10 is sufficiently large to suppress rolling over.

[0056] If all of the above conditions are met, the control unit 17b determines that the execution conditions for the braking force maintenance control are met. On the other hand, if at least one of the above conditions is not met, the control unit 17b determines that the execution conditions for the braking force maintenance control are not met. By using the above execution conditions, it is possible to suppress the vehicle 10 from rolling downhill by the braking force maintenance control when the vehicle 10 is stopped in a state where it can start moving.

[0057] The acquisition unit 17a can acquire information about the speed of the vehicle 10 based on the detection results of the wheel speed sensors 15. The acquisition unit 17a can also acquire information about the yaw rate of the vehicle 10 based on the detection results of the inertial measurement unit 16.

[0058] If it is determined that the execution condition for braking force maintenance control is satisfied (step S102 / YES), the process proceeds to step S103. In step S103, the control unit 17b starts braking force maintenance control. On the other hand, if it is determined that the execution condition for braking force maintenance control is not satisfied (step S102 / NO), the process flow shown in FIG. 4 ends.

[0059] After step S103, in step S104, the control unit 17b determines whether the reliability of the wheel cylinder pressure sensor 48 is higher than a reference value.

[0060] As will be described later, the wheel cylinder pressure detected by the wheel cylinder pressure sensor 48 is used as an index of the braking force actually acting on the vehicle 10. Then, braking force increase control is executed based on the comparison result between the wheel cylinder pressure and the target hydraulic pressure. However, depending on the reliability of the wheel cylinder pressure sensor 48, it is not always appropriate to use the detection result of the wheel cylinder pressure sensor 48 to determine whether or not to execute braking force increase control.

[0061] When the reliability of the wheel cylinder pressure sensor 48 is higher than the standard, it corresponds to a case where it is appropriate to determine whether or not to execute braking force increase control using the detection result of the wheel cylinder pressure sensor 48. On the other hand, when the reliability of the wheel cylinder pressure sensor 48 is lower than the standard, it corresponds to a case where it is not appropriate to determine whether or not to execute braking force increase control using the detection result of the wheel cylinder pressure sensor 48.

[0062] For example, the control unit 17b determines that the reliability of the wheel cylinder pressure sensor 48 is lower than the standard when an abnormality is detected in the communication between the wheel cylinder pressure sensor 48 and the control device 17. Also, for example, the control unit 17b determines that the reliability of the wheel cylinder pressure sensor 48 is lower than the standard when a signal indicating an abnormality is received from the wheel cylinder pressure sensor 48.

[0063] If it is determined that the reliability of the wheel cylinder pressure sensor 48 is higher than the standard (step S104 / YES), the process proceeds to step S105. On the other hand, if it is determined that the reliability of the wheel cylinder pressure sensor 48 is lower than the standard (step S104 / NO), the process proceeds to step S108. The process from step S108 onwards will be described later.

[0064] If the judgment in step S104 is YES (i.e., if the reliability of the wheel cylinder pressure sensor 48 is judged to be higher than the standard), in step S105, the control unit 17b judges whether the wheel cylinder pressure detected by the wheel cylinder pressure sensor 48 is lower than the target hydraulic pressure.

[0065] As described above, the wheel cylinder pressure detected by the wheel cylinder pressure sensor 48 is used as an index showing the braking force actually acting on the vehicle 10. Here, the target hydraulic pressure is a target value of the wheel cylinder pressure for preventing the vehicle 10 from rolling downhill. In other words, the target hydraulic pressure is used as an index showing a target value of the braking force for preventing the vehicle 10 from rolling downhill.

[0066] For example, the control unit 17b sets the target hydraulic pressure based on the weight of the vehicle 10 and the gradient of the road surface on which the vehicle 10 is stopped. Specifically, the control unit 17b sets a higher value as the target hydraulic pressure as the weight of the vehicle 10 increases. Furthermore, the control unit 17b sets a higher value as the gradient of the road surface on which the vehicle 10 is stopped increases. The acquisition unit 17a can acquire information about the gradient of the road surface on which the vehicle 10 is stopped based on the detection results of the inertial measurement unit 16.

[0067] As described above, when the vehicle 10 is stopped, braking force maintenance control is executed to prevent the vehicle 10 from rolling downhill. However, even when the solenoid valve is closed, some brake fluid may leak through the flow path of the hydraulic control unit 13. This causes the wheel cylinder pressure to gradually decrease over time. This may result in the wheel cylinder pressure falling below the target hydraulic pressure.

[0068] If it is determined that the wheel cylinder pressure is lower than the target hydraulic pressure (step S105 / YES), the process proceeds to step S106. On the other hand, if it is determined that the wheel cylinder pressure is higher than the target hydraulic pressure (step S105 / NO), the process proceeds to step S108. The process from step S108 onwards will be described later.

[0069] If the determination in step S105 is YES (that is, if it is determined that the wheel cylinder pressure is lower than the target hydraulic pressure), the control section 17b executes braking force increase control in step S106.

[0070] Next, in step S107, the control unit 17b determines whether or not the vehicle 10 has started moving. For example, if the vehicle 10 has started moving automatically due to adaptive cruise control, the determination in step S107 is YES.

[0071] If it is determined that the vehicle 10 has not started moving (step S107 / NO), the process returns to step S104. On the other hand, if it is determined that the vehicle 10 has started moving (step S107 / YES), the process flow shown in FIG. 4 ends.

[0072] As described above, after the braking force maintenance control is initiated, the wheel cylinder pressure may fall below the target hydraulic pressure. In such a case, the determination in step S105 is YES, and the braking force increase control is executed in step S106. This increases the wheel cylinder pressure, and the wheel cylinder pressure returns to a state higher than the target hydraulic pressure. Therefore, even if the wheel cylinder pressure falls below the target hydraulic pressure, it is possible to prevent the vehicle 10 from rolling downhill.

[0073] Here, even if the process of executing braking force increase control when the wheel cylinder pressure is lower than the target hydraulic pressure (i.e., the process of steps S105 and S106) is performed, there may be cases where the vehicle 10 rolls over. For example, due to the detection accuracy or responsiveness of the wheel cylinder pressure sensor 48, a discrepancy occurs between the actual wheel cylinder pressure and the wheel cylinder pressure detected by the wheel cylinder pressure sensor 48, and the situation where the wheel cylinder pressure is lower than the target hydraulic pressure cannot be quickly resolved, resulting in the vehicle rolling over. Therefore, even in such cases, the processes of steps S108 and S109 described below are performed as processes to prevent the vehicle 10 from rolling over.

[0074] As described above, for example, if the determination in step S105 is NO (i.e., if it is determined that the wheel cylinder pressure is higher than the target hydraulic pressure), the process proceeds to step S108. In step S108, the control unit 17b determines whether or not the occurrence of the vehicle 10 rolling downhill has been detected.

[0075] For example, the control unit 17b can detect the occurrence of a skid of the vehicle 10 based on the detection results of each wheel speed sensor 15. Specifically, the control unit 17b can determine that a skid of the vehicle 10 has occurred when each wheel speed sensor 15 indicates a predetermined wheel speed or higher.

[0076] If it is determined that the occurrence of rolling down of the vehicle 10 has been detected (step S108 / YES), the process proceeds to step S109. In step S109, the control unit 17b executes braking force increase control, and the process proceeds to step S107. On the other hand, if it is determined that the occurrence of rolling down of the vehicle 10 has not been detected (step S108 / NO), the braking force increase control is not executed, and the process proceeds to step S107.

[0077] As described above, when the wheel cylinder pressure is higher than the target hydraulic pressure and the control unit 17b detects that the vehicle 10 is about to roll, the control unit 17b further executes braking force increase control. In other words, when the control unit 17b detects that the vehicle 10 is about to roll despite the braking force of the vehicle 10 being increased by braking force increase control that is performed based on the comparison result between the wheel cylinder pressure and the target hydraulic pressure, the control unit 17b further executes braking force increase control. This makes it possible to suppress rolling of the vehicle 10 even if the process of executing braking force increase control is performed when the wheel cylinder pressure is lower than the target hydraulic pressure.

[0078] As described above, if the determination in step S104 is NO (i.e., if the reliability of the wheel cylinder pressure sensor 48 is determined to be lower than the standard), the process also proceeds to step S108. In this way, if the reliability of the wheel cylinder pressure sensor 48 is lower than the standard, the control unit 17b prohibits the process of executing the braking force increase control when the wheel cylinder pressure is lower than the target hydraulic pressure (i.e., the processes of steps S105 and S106). Then, if the control unit 17b detects the occurrence of a rollover of the vehicle 10 in a state in which the process of executing the braking force increase control when the wheel cylinder pressure is lower than the target hydraulic pressure is prohibited (step S108 / YES), the control unit 17b executes the braking force increase control (step S109).

[0079] The above describes an example of the processing performed by the control device 17. However, the processing performed by the control device 17 is not limited to the above example of processing, and may be, for example, a processing obtained by appropriately modifying the above example of processing.

[0080] For example, in the above description, an example has been described in which the processing flow shown in FIG. 4 starts while adaptive cruise control is being executed. In this example, the processing from step S103 onwards is performed when the vehicle 10 stops as a result of decelerating in response to a deceleration command from adaptive cruise control. However, the processing flow shown in FIG. 4 may also be started when adaptive cruise control is not being executed. In this case, the processing from step S103 onwards is performed when the vehicle 10 stops as a result of decelerating in response to a brake operation by the driver. In this case, a condition that the driver has selected a mode that permits braking force maintenance control may be added to the execution conditions for braking force maintenance control in step S102.

[0081] Furthermore, for example, while the braking force maintenance control is being executed (for example, before step S104, before step S105, or before step S106), the control unit 17b may determine whether the vehicle 10 is stopped on a downhill road and the shift position of the vehicle 10 is in the D range, or whether the vehicle 10 is stopped on an uphill road and the shift position of the vehicle 10 is in the R range. Then, when the vehicle 10 is stopped on a downhill road and the shift position of the vehicle 10 is in the D range, or when the vehicle 10 is stopped on an uphill road and the shift position of the vehicle 10 is in the R range, the control unit 17b may proceed to step S108 and execute braking force increase control depending on the result of the determination as to whether or not the occurrence of the vehicle 10 rolling downhill has been detected.

[0082] The D range refers to a shift position where a driving force in a direction to move the vehicle 10 forward is transmitted to the drive wheels in response to an accelerator operation by the driver, and the R range refers to a shift position where a driving force in a direction to move the vehicle 10 backward is transmitted to the drive wheels in response to an accelerator operation by the driver. However, the names of the shift positions corresponding to the D range and the R range may be different from those in the above example. The acquisition unit 17a can acquire information about the shift position from, for example, a sensor provided in the vehicle 10 that detects the shift position. The acquisition unit 17a can also acquire information indicating whether the road surface on which the vehicle 10 is stopped is a downhill road or an uphill road based on the detection result of the inertial measurement unit 16.

[0083] When the vehicle 10 is stopped on a downhill road and the shift position of the vehicle 10 is in D range, or when the vehicle 10 is stopped on an uphill road and the shift position of the vehicle 10 is in R range, even if the wheel cylinder pressure is higher than the target hydraulic pressure, the vehicle 10 may roll over due to the driving force output from the driving source 12. In such a case, by performing a process (steps S108 and S109) to execute braking force increase control in accordance with the determination result of whether or not the occurrence of rolling over of the vehicle 10 has been detected, it is possible to suppress the vehicle 10 from rolling over even if the vehicle 10 does roll over.

[0084] <Effects of the control device> The effects of the control device 17 according to the embodiment of the present invention will be described.

[0085] The control device 17 includes a control unit 17b that executes braking force increase control to automatically increase the braking force of the vehicle 10. The control unit 17b compares the braking force with a threshold value while the vehicle 10 is stopped, and performs a first process to execute braking force increase control (the process of step S106 in the above example) if the braking force is equal to or less than the threshold value (in the above example, if the wheel cylinder pressure is lower than the target hydraulic pressure). The control unit 17b also performs a second process to execute braking force increase control (the process of step S109 in the above example) if it detects that the vehicle 10 is about to roll over despite the braking force being increased by the first process. This prevents the vehicle 10 from rolling over by the first process before the vehicle 10 rolls over, and can also prevent the vehicle 10 from rolling over even if the vehicle 10 does roll over. This improves the reliability of preventing the vehicle 10 from rolling over.

[0086] Preferably, in the control device 17, the control unit 17b compares the braking force with a threshold value (in the above example, compares the wheel cylinder pressure with the target hydraulic pressure) based on the detection result of a sensor for detecting the braking force (in the above example, wheel cylinder pressure sensor 48), and if the reliability of the sensor is lower than a standard, prohibits the first process, and if it detects that the vehicle 10 is about to roll over while the first process is prohibited, performs a third process that executes braking force increase control (in the above example, the process of step S109).Therefore, if it is not appropriate to determine whether or not to execute braking force increase control using the detection result of the sensor, it is possible to inhibit the vehicle 10 from rolling over if the vehicle 10 does start to roll over.

[0087] Note that the control unit 17b may not prohibit the first process depending on the reliability of the sensor for detecting the braking force (in the above example, the wheel cylinder pressure sensor 48). For example, step S104 may be omitted from the process flow shown in FIG.

[0088] Preferably, in the control device 17, the control unit 17b executes adaptive cruise control that automatically controls the speed of the vehicle 10 so that the vehicle 10 follows a preceding vehicle, and executes the first process and the second process when the vehicle 10 automatically stops while the adaptive cruise control is being executed. This improves the reliability of preventing the vehicle 10 from rolling downhill during the execution of adaptive cruise control, in which most of the driving operations by the driver are left to the control device 17, even with regard to stopping and starting the vehicle 10. This improves the convenience and comfort of adaptive cruise control, which automatically controls the traveling of the vehicle 10 while taking over some or all of the driving operations by the driver.

[0089] As described above, the control unit 17b may perform the first process and the second process when the vehicle 10 stops while the adaptive cruise control is not being executed.

[0090] Preferably, in the control device 17, the control unit 17b starts braking force maintenance control that automatically maintains braking force while the vehicle 10 is stopped, and performs the first process and the second process after starting the braking force maintenance control. As a result, when the vehicle 10 is stopped, the braking force maintenance control can suppress the vehicle 10 from rolling down, and then the first process and the second process can further effectively suppress the vehicle 10 from rolling down. Therefore, the reliability of suppressing the vehicle 10 from rolling down can be more effectively improved.

[0091] Note that the control unit 17b may perform the first process and the second process without starting the braking force maintenance control while the vehicle 10 is stopped. For example, when the process flow shown in Fig. 4 starts when adaptive cruise control is not being executed, step S103 may be omitted from the process flow shown in Fig. 4. In that case, for example, in the braking force increase control of steps S106 and S109, the control unit 17b automatically amplifies the braking force acting on the vehicle 10 relative to the braking force corresponding to the brake operation by the driver.

[0092] The above describes a preferred embodiment of the present invention with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiment, and various modified or altered examples within the scope of the claims also fall within the technical scope of the present invention.

[0093] For example, the processes described herein using flowcharts do not necessarily have to be performed in the order shown in the flowcharts, some process steps may be performed in parallel, additional process steps may be employed, and some process steps may be omitted.

[0094] Furthermore, for example, the series of processes performed by the control device 17 described above may be realized using software, hardware, or a combination of software and hardware. The programs constituting the software are stored in advance in, for example, a storage medium provided inside or outside the information processing device. [Explanation of symbols]

[0095] 10 vehicles 11 Steering mechanism 12 Power source 13 Hydraulic control unit 14 Ambient environment sensor 15 Wheel speed sensor 16 Inertial Measurement Unit 17 Control device 17a Acquisition Department 17b Control section 20 Brake System 21 Brake pedal 22 Booster 23 Master cylinder 24 reservoir 25 Wheel cylinder 26 wheels 31 Main channel 32 Subchannel 33 Supply channel 41 Inlet valve 42 Release valve 43 First Valve 44 Second valve 45 Accumulator 46 Pump 47 Motor 48 Wheel cylinder pressure sensor (sensor)

Claims

1. a control unit (17b) that executes braking force increase control to automatically increase the braking force of the vehicle (10); The control unit (17b) performs the following while the vehicle (10) is stopped: a first process of comparing the braking force with a threshold value and executing the braking force increase control when the braking force is equal to or less than the threshold value; a second process for further executing the braking force increase control when it is detected that the vehicle (10) is sliding down despite the braking force being increased by the first process; Control device.

2. The control unit (17b) comparing the braking force with the threshold value based on a detection result of a sensor (48) for detecting the braking force; If the reliability of the sensor (48) is lower than a standard, prohibiting the first process; a third process for executing the braking force increase control when the occurrence of a rollover of the vehicle (10) is detected while the first process is prohibited; The control device according to claim 1 .

3. The control unit (17b) Executing adaptive cruise control to automatically control the speed of the vehicle (10) so that the vehicle (10) follows a preceding vehicle; When the vehicle (10) automatically stops while the adaptive cruise control is being executed, the first process and the second process are performed. The control device according to claim 1 .

4. The control unit (17b) performs the following while the vehicle (10) is stopped: starting a braking force maintenance control for automatically maintaining the braking force; the first process and the second process are performed after the braking force maintenance control is started. The control device according to any one of claims 1 to 3.

5. A vehicle control method, comprising: a control unit (17b) of the control device (17) executes braking force increase control to automatically increase the braking force of the vehicle (10); The control unit (17b) performs the following while the vehicle (10) is stopped: a first process of comparing the braking force with a threshold value and executing the braking force increase control when the braking force is equal to or less than the threshold value; a second process for further executing the braking force increase control when it is detected that the vehicle (10) is sliding down despite the braking force being increased by the first process; Control method.

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