Vehicle control device, vehicle control program, and vehicle control method

Abstract

To improve safety by reducing an idle running distance of a vehicle.SOLUTION: A vehicle 10 comprises a traveling motor 23 and a brake device 27 which are braking force generation devices capable of generating braking force without requiring brake operation by a driver, and also comprises a driving support ECU 20 for supporting driving of the vehicle 10. The driving support ECU 20 determines that sudden steering is performed by the driver, and on the basis of a result of the determination, controls the traveling motor 23 into a regenerative state and issues instructions for actuation of the brake device 27 so as to cause braking force to be generated by using the traveling motor 23 and the brake device 27.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] When an obstacle such as a small animal suddenly appears in front of a traveling vehicle, it is desirable for the vehicle to take appropriate action in response to the obstacle. For example, Patent Document 1 proposes a technology that determines whether a collision with the obstacle can be avoided based on the result of obstacle detection by an obstacle sensor and the state of braking operation by the driver, and if it determines that the collision cannot be avoided by braking operation by the driver, controls the braking device on the vehicle side in accordance with the vehicle deceleration required to assist in avoiding the obstacle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5166883 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, while a vehicle is traveling, the driver may suddenly operate the steering wheel (sudden steering) in response to the above-mentioned sudden jumping out. In this case, it is thought that the driver's braking operation may be delayed in relation to the steering operation, and in that case, it is assumed that the free-running distance, which is the distance until the brakes actually start to apply, will be longer. There is concern that a longer free-running distance will make it more difficult to avoid obstacles, etc. As such, there is still room for technological improvement in order to shorten the free-running distance of a vehicle and improve safety.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its main object is to provide a vehicle control device, a vehicle control program, and a vehicle control method that can shorten the vehicle's free-running distance and improve safety. [Means for solving the problem]

[0006] The following describes means for solving the above problems.

[0007] The present invention is applied to a vehicle equipped with a braking force generating device capable of generating braking force without the driver's brake operation, and is equipped with a sudden steering judgment unit that judges whether sudden steering has occurred in the vehicle, and a brake control unit that generates braking force by controlling the braking force generating device based on the judgment result that sudden steering has occurred.

[0008] According to the present invention, when the driver performs sudden steering, the braking force generating device is controlled so as to generate braking force in response to the sudden steering. This configuration, which generates braking force quickly without waiting for the driver to brake, can shorten the free-running distance of the vehicle compared to a configuration in which braking force is generated in response to, for example, the brake operation after sudden steering. In other words, it is possible to prevent a delay in the driver's brake operation from directly leading to a delay in braking. This can contribute to improving the safety of the vehicle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a driving assistance system according to an embodiment; [Figure 2] 4 is a flowchart showing an automatic braking process. [Figure 3] 10 is a flowchart showing a state transition process. [Figure 4] 10 is a flowchart showing a charging restriction process. [Figure 5] 4 is a timing chart illustrating an example of automatic braking processing when the first upper limit has not been reached. [Figure 6] 4 is a timing chart illustrating an example of automatic braking processing when a first upper limit is exceeded. [Figure 7] FIG. 2 is a diagram illustrating an example of vehicle braking. [Figure 8] 10 is a flowchart showing a state transition process in another example. [Figure 9] 10 is a timing chart illustrating a change in braking force in another example. [Figure 10] 10 is a timing chart illustrating a change in braking force in another example. [Figure 11] 10 is a flowchart showing a process for raising an upper limit of an SOC in another example. [Figure 12] 10 is a flowchart showing an automatic braking process according to another example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle control device according to an embodiment of the present invention will now be described with reference to the accompanying drawings. This embodiment is embodied as a driving assistance system for an electric vehicle. First, a schematic configuration of the driving assistance system will be described with reference to FIG.

[0011] The vehicle 10 is an EV vehicle that travels by supplying power stored in a battery 21 to a traction motor 23 (rotating electric machine) via an inverter 22. A motor ECU 24 is connected to the inverter 22, and the traction motor 23 is switched between a power running state and a regenerative state by inverter control of the motor ECU 24. The motor ECU 24 controls the power supplied from the battery 21 to the traction motor 23 in the power running state, and controls the power supplied from the traction motor 23 to the battery 21 in the regenerative state.

[0012] The vehicle 10 is also provided with a hydraulic brake device 27 that generates a braking force on each wheel 11 of the vehicle 10. The brake device 27 is a friction brake device that includes brake members 28, such as brake pads and calipers, provided on each wheel 11, and a drive module 29 that drives the brake members 28. The drive module 29 has a well-known hydraulic mechanism. The brake device 27 generates a braking force by friction on each wheel 11 when the driver depresses a brake pedal (not shown).

[0013] The driving assistance ECU 20 is connected to the motor ECU 24 and the brake device 27, and motor control and brake control can be performed as driving assistance control by the driving assistance ECU 20. The driving assistance ECU 20 is connected to an object detection device 31 that detects objects present around the vehicle 10, a brake sensor 32 that detects the amount of brake pedal operation, a steering sensor 33 that detects the amount of steering operation (steering angle), a wheel speed sensor 34 that detects the rotation speed of each wheel 11, a yaw rate sensor 35 that detects the yaw rate of the vehicle 10, and a driver camera 36 that monitors the state of the driver in the vehicle cabin. The object detection device 31 is a camera that captures images of the vehicle's surroundings, a distance measurement sensor that measures the distance to an object, etc. The driver camera 36 is an in-vehicle camera that acquires information such as the driver's posture, line of sight, blinking, and facial direction.

[0014] The driving assistance ECU 20 calculates command values related to the drive of the traction motor 23 and command values related to the drive of the brake device 27 based on the detection results of the above-mentioned sensors, etc., and outputs these command values to the motor ECU 24 and the brake device 27 as appropriate. This enables the driving assistance ECU 20 to control the traction motor 23 and the brake device 27. In particular, in this embodiment, the braking control by the driving assistance ECU 20 can implement regenerative braking, which generates braking force (regenerative braking force) by putting the traction motor 23 into a regenerative state, and friction braking, which generates braking force (friction braking force) by driving the brake device 27. The driving assistance ECU 20 corresponds to the "braking force generation device," and the driving assistance ECU 20 corresponds to the "vehicle control device."

[0015] Furthermore, when the driver is in a state of loss of consciousness due to drowsiness, illness, or the like, the driving assistance ECU 20 determines that the driver is in a state of loss of consciousness based on the analysis results of the image from the driver camera 36.

[0016] The motor ECU 24 has a function of calculating the SOC (remaining capacity) of the battery 21, and the SOC calculated by the motor ECU 24 is output to the driving assistance ECU 20. As is well known, the SOC is updated successively by adding or subtracting the charging current and discharging current flowing through the battery 21 and calculating an integrated current value. The motor ECU 24 also controls the charging and discharging of the battery 21 so that the SOC of the battery 21 is maintained within a range defined between a predetermined SOC lower limit value and a predetermined SOC upper limit value. For example, the SOC lower limit value is 20%, and the SOC upper limit value is 80%.

[0017] When an obstacle such as a small animal suddenly appears in front of the vehicle 10 while it is in motion, the driver may suddenly operate the steering wheel in response to the sudden appearance of the obstacle before operating the brake pedal. Such a sudden steering operation may also occur if the driver loses consciousness while driving the vehicle and leans their body. If the sudden steering operation precedes the sudden operation of the brake pedal, the free-running distance until braking force is generated becomes longer. In other words, the delay in operating the brake pedal delays the timing at which braking force is generated. The driving assistance system in this embodiment is characterized by initiating automatic brake control when the driver suddenly operates the steering wheel, thereby shortening the free-running distance.

[0018] Hereinafter, a configuration for realizing automatic brake control, specifically, automatic brake processing executed as periodic processing at a predetermined interval in the driving assistance ECU 20, will be described with reference to the flowchart of FIG.

[0019] In the automatic braking process, first, in step S101, it is determined whether or not a braking flag is set. The braking flag is set when automatic braking control is initiated in response to a sudden steering operation (sudden steering), and is cleared when the automatic braking control is terminated. If the braking flag is not set, the process proceeds to step S102, where it is determined whether or not sudden steering has occurred. Specifically, the driving assistance ECU 20 calculates the jerk of the steering angle from the detection information of the steering sensor 33, and determines that sudden steering has occurred if the jerk of the steering angle exceeds a predetermined threshold. The jerk of the steering angle may be calculated as the rate of change of acceleration per unit time.

[0020] If it is determined that no sudden steering has been performed, the automatic braking process is terminated. On the other hand, if it is determined that sudden steering has been performed, the process proceeds to step S103. In step S103, it is determined whether or not the brake pedal has been operated (manually operated) by the driver based on the detection information from the brake sensor 32. If it is determined that the brake pedal has been operated, the automatic braking process is terminated. If it is determined that the brake pedal has not been operated, the automatic braking start process of steps S104 to S110 is executed.

[0021] In the automatic brake initiation process, first, the state of the road surface on which the vehicle 10 is traveling and the turning state of the vehicle 10 are grasped (step S104). For example, the road surface μ may be calculated based on the rotational speed of each wheel 11 detected by the wheel speed sensor 34 and the vehicle speed, and the road surface μ may be grasped as the road surface state. In addition, the turning state of the vehicle 10 may be calculated based on the yaw rate detected by the yaw rate sensor 35 and the vehicle speed.

[0022] Then, in step S105, a required braking force PX for the automatic brake control is set. This required braking force PX is the total amount of braking to be applied to the vehicle 10, and at the start of the automatic brake control, it is the braking force that is the sum of the regenerative braking force realized by the regeneration of the traction motor 23 and the friction braking force realized by the drive of the brake device 27. At this time, the required braking force PX is preferably set based on the road surface condition and turning state grasped in step S104 and the vehicle speed of the vehicle 10. For example, when the road surface μ is low due to rain or the like, or when the vehicle is turning (when the turning radius is large), the required braking force PX is kept low to prevent tires from locking due to the automatic brake control. In other words, the required braking force PX is set to be the maximum braking force within a range that can avoid tires from locking due to the automatic brake control.

[0023] In the next step S106, the required braking force PX is divided into a regenerative braking force realized by regeneration of the traction motor 23 and a frictional braking force realized by driving the brake device 27. At this time, the torque characteristics of the traction motor 23, which define the relationship between the motor rotation speed (vehicle speed) and torque, are used to set the regenerative braking force based on the motor rotation speed at each time. This regenerative braking force is the upper limit of the regenerative braking force of the traction motor 23, which is determined based on the torque characteristics. The regenerative braking force (upper limit of the regenerative braking force) may be set based on the road surface condition and the turning condition. For example, the lower the road surface condition, the smaller the regenerative braking force, and the smaller the turning radius, the smaller the regenerative braking force. The regenerative braking force may be set based on either the road surface condition or the turning condition. Furthermore, the frictional braking force is calculated by subtracting the regenerative braking force from the required braking force PX to compensate for the shortfall of the regenerative braking force relative to the required braking force PX, at least at the start of automatic brake control.

[0024] In the next step S107, the SOC upper limit of the battery 21 is increased. Specifically, the SOC upper limit of the battery 21 is increased from upper limit L1, which is the normal SOC upper limit, to upper limit L2, which is the emergency SOC upper limit, and charging beyond upper limit L1 is permitted. This prevents regenerative braking force from being lost due to regeneration lapse, even when automatic brake control is executed under conditions in which the actual SOC of the battery 21 is close to upper limit L1. Note that upper limit L2 can be any value greater than upper limit L1.

[0025] Thereafter, in steps S108 and S109, automatic brake control is started. Specifically, in step S108, a regeneration command is output to put the travel motor 23 into a regenerative state (regenerative brake ON), and in step S109, an operation command is output to operate the brake device 27 (friction brake ON). This starts the regenerative operation of the travel motor 23 and starts hydraulic operation of the brake device 27. Although the regenerative command for the travel motor 23 and the operation command for the brake device 27 are output simultaneously, there is a difference in the time until the regenerative braking force and the friction braking force are actually generated. Specifically, the friction braking force is generated later than the regenerative braking force.

[0026] Thereafter, the braking flag is set in step S110, and the process is temporarily terminated.

[0027] After automatic brake control is initiated due to sudden steering, that is, if a positive determination is made in step S101 due to the setting of the braking flag, the process proceeds to step S111. In step S111, it is determined whether or not the brake pedal has been operated (manually operated) by the driver based on detection information from the brake sensor 32. If no manual operation is being performed, a negative determination is made in step S111 and the process proceeds to step S112. In step S112, it is determined whether or not the vehicle speed has become 0 and the vehicle has stopped. If the vehicle has not stopped, state transition processing is executed in step S113, and then this processing is temporarily terminated. Hereinafter, the state transition processing will be described with reference to FIG. 3.

[0028] The state transition process is a process for transitioning from a state (first state) in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state (second state) in which the required braking force PX is generated by the frictional braking force after the frictional braking force by the brake device 27 starts to be applied after the start of automatic brake control. In this state transition process, first, in step S201, it is determined whether or not the state is before transition. If the determination in step S201 is affirmative, the actual SOC of the battery 21 is acquired in step S202.

[0029] In the following step S203, it is determined whether the actual SOC is less than the upper limit L1. If the actual SOC is less than the upper limit L1, the process proceeds to step S204, where it is determined whether the brake device 27 is currently capable of generating a frictional braking force equivalent to the required braking force PX. Specifically, for example, the brake device 27 is determined to be capable of generating a frictional braking force equivalent to PX on the condition that a predetermined time has elapsed since the activation command to the brake device 27 was issued. This predetermined time may be, for example, a predetermined fixed time or a time that is variably set depending on the required braking force PX. For example, the predetermined time may be set to a longer time as the required braking force PX increases. Alternatively, in step S204, the brake hydraulic pressure of the brake device 27 may be detected, and based on the detected information, it may be determined whether the brake device 27 is capable of generating a frictional braking force equivalent to PX.

[0030] If the brake device 27 is in a state where it can generate a frictional braking force equivalent to PX, it is determined that a state transition is possible, and the process proceeds to step S205. In step S205, a transition is made from a state in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state in which the required braking force PX is generated by the frictional braking force. At this time, the regenerative command for the travel motor 23 is turned off, and the frictional braking force of the brake device 27 is increased to the required braking force PX. Note that when the frictional braking force is increased to the required braking force PX, it is also possible to gradually reduce the regenerative braking force so that the required braking force PX does not temporarily decrease.

[0031] On the other hand, if the actual SOC exceeds the upper limit L1 in step S203, the process proceeds to step S206, where an SOC flag indicating that the actual SOC has exceeded the upper limit L1 is set.

[0032] In the next step S207, it is determined whether or not the brake device 27 is generating a frictional braking force. This determination may be made, for example, based on the elapsed time since the activation command to the brake device 27. If the frictional braking force is being generated, the process proceeds to step S205, where a transition is made from a state in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state in which the required braking force PX is generated by the frictional braking force. If the frictional braking force is not being generated, the process proceeds to the subsequent step S208.

[0033] In step S208, it is determined whether the actual SOC exceeds the upper limit L2. If the actual SOC exceeds the upper limit L2, the process proceeds to step S205, where a transition is made from a state in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state in which the required braking force PX is generated by the frictional braking force. If the actual SOC does not exceed the upper limit L2, the process is terminated.

[0034] Returning to the description of the automatic braking process in FIG. 2, if a positive determination is made in either step S111 or S112, the process proceeds to step S114. In step S114, the automatic braking control is released, and the braking control is shifted to normal braking control corresponding to manual braking by the driver. In the following step S115, the SOC upper limit value of the battery 21 is returned to the normal upper limit value L1. In addition, in step S116, the braking flag is cleared, and this process ends. Note that after the vehicle is stopped, a process to maintain the vehicle stopped state (for example, turning on the electric parking brake) may be executed.

[0035] 2, the actual SOC of the battery 21 may exceed the upper limit L1 during regeneration by the traction motor 23. In this case, the driving assistance ECU 20 may limit the regenerative operation of the traction motor 23 when the actual SOC exceeds the upper limit L1. Specifically, the driving assistance ECU 20 executes the charge limiting process shown in FIG. 4 at predetermined intervals.

[0036] In Fig. 4, in step S301, it is determined whether or not the SOC flag is set. This SOC flag is a flag that is set in accordance with the determination result of step S203 in Fig. 3. If the SOC flag is set, the process proceeds to step S302, where it is determined whether or not the actual SOC currently exceeds the upper limit value L1.

[0037] If it is determined in step S302 that the actual SOC exceeds the upper limit L1, the process proceeds to step S303, where a charge-restricted state is established in which charging of the battery 21 is restricted. Specifically, even if the vehicle is decelerating while traveling, regenerative charging of the traction motor 23 is prohibited or the regenerative power is set to a predetermined level or less. If it is determined that the actual SOC does not exceed the upper limit L1, the process proceeds to step S304, where the SOC flag is cleared. Note that if the SOC flag is set, it is also possible to consume battery power by actively using the on-board electrical loads (using the load in excess of the original drive demand).

[0038] The flow of the automatic braking process will be described below with reference to the timing charts in Figures 5 and 6. The automatic braking process differs depending on whether the actual SOC of the battery 21 does not exceed the upper limit value L1 or not. First, the flow of the automatic braking process when the actual SOC of the battery 21 does not exceed the upper limit value L1 will be described with reference to Figure 5. Note that Figures 5 and 6 illustrate an example in which, when a vehicle suddenly jumps out into the road while the vehicle 10 is traveling, the driver suddenly operates the steering wheel but does not operate the brake pedal.

[0039] At timing ta1, the driving assistance ECU 20 determines that sudden steering has been performed. Based on this determination result, a braking flag is set, and automatic brake control by the driving assistance system is initiated. In the automatic brake control, the SOC upper limit value of the battery 21 is raised from upper limit value L1 to upper limit value L2, and charging beyond upper limit value L1 is permitted. Then, a regeneration command for the driving motor 23 is output, and an operation command for the brake device 27 is output.

[0040] At timing ta1, the traction motor 23 is switched to a regenerative state. Regenerative braking by the traction motor 23 has better response than friction braking, and the regenerative state allows regenerative braking force to be generated quickly. This allows the vehicle 10 to quickly begin decelerating after sudden steering. Thereafter, while the regenerative braking is operating, the battery 21 is charged by the regenerative power of the traction motor 23, and the actual SOC of the battery 21 gradually increases.

[0041] The frictional braking force generated by the brake device 27 starts to take effect later than the regenerative braking force, so the frictional braking force is applied at timing ta2, which is later than timing ta1. In other words, from timing ta2 onwards, both the regenerative braking force and the frictional braking force are generated. After the regenerative braking force reaches its upper limit, it is maintained at that upper limit. The regenerative braking force and the frictional braking force then generate a braking force equivalent to the required braking force PX on the vehicle 10.

[0042] Then, at timing ta3, the brake device 27 is deemed to be in a state capable of generating a frictional braking force equivalent to PX, and a transition is made from a state in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state in which the required braking force PX is generated by the frictional braking force. At this time, the regeneration of the traction motor 23 is stopped, and the increase in the actual SOC stops. In the example shown in FIG. 5, although the actual SOC increases during the operation of the regenerative brake, the actual SOC remains below the upper limit value L1 throughout. After ta3, the brake device 27 generates a frictional braking force equivalent to PX.

[0043] Thereafter, for example, at timing ta4 when the vehicle speed becomes 0, the braking flag is cleared and the automatic brake control is released. At this time, the operation command from the driving assistance ECU 20 to the brake device 27 is stopped and normal brake control is restored. Also, the SOC upper limit value of the battery 21 is returned from upper limit value L2 to upper limit value L1.

[0044] Next, the flow of automatic braking when the actual SOC of the battery 21 exceeds the upper limit value L1 will be described with reference to the timing chart of FIG.

[0045] At timing tb1, based on the determination that sudden steering has occurred, the braking flag is set, the upper limit of the SOC is raised, and a regeneration command for the driving motor 23 and an operation command for the brake device 27 are output. This is similar to timing ta1 in FIG. 5. However, compared to the example shown in FIG. 5, the difference between the actual SOC at the start of automatic brake control and the upper limit L1 is smaller. Therefore, at timing tb2, the actual SOC exceeds the upper limit L1 due to regeneration by the driving motor 23.

[0046] After that, at timing tb3, it is determined that the actual SOC exceeds the upper limit value L1 and that the brake device 27 is generating a frictional braking force, so a transition is made from a state in which the required braking force PX is generated by the regenerative braking force and the frictional braking force to a state in which the required braking force PX is generated by the frictional braking force. After tb3, the brake device 27 generates a frictional braking force equivalent to PX.

[0047] Thereafter, for example, at timing tb4 when the vehicle speed becomes 0, the braking flag is cleared, the automatic brake control is released, and normal brake control is restored.

[0048] 6, during automatic braking control, the actual SOC of the battery 21 exceeds the upper limit L1, and the SOC is exceeded at the end of the automatic braking control. In such a case, charging of the battery 21 is limited while the vehicle is running after the automatic braking control is released.

[0049] That is, after the automatic brake control is released, the vehicle 10 resumes traveling at timing tb5. While the vehicle is traveling, battery power is consumed as the traction motor 23 is powered, and the actual SOC of the battery 21 gradually decreases. Thereafter, at timing tb6, the accelerator is released and the vehicle 10 enters a deceleration state. However, because the actual SOC exceeds upper limit value L1, regenerative power generation by the traction motor 23 is limited, and an increase in the actual SOC is suppressed. Note that if the driver applies the brakes while the vehicle is decelerating, a braking force is generated by the friction brake as shown in the figure.

[0050] As described above in detail, in this embodiment, automatic brake control is initiated when sudden steering is performed. Therefore, compared to a conventional vehicle (see FIG. 7(a)) that does not have a function for executing this automatic brake control, the free running distance when the brake pedal is operated with a delay after sudden steering can be shortened (see FIG. 7(b)). This makes it possible to shorten the distance (stopping distance) from the position where sudden steering occurs to the position where the vehicle 10 stops. In other words, it is possible to prevent a delay in the driver's brake operation from directly leading to a delay in braking. This can contribute to improving the safety of the vehicle.

[0051] With the brake device 27, it is necessary to increase the brake hydraulic pressure to generate braking force, and there is a slight delay before the braking force is generated. In contrast, the time it takes for the regenerative brake of the travel motor 23 to generate braking force is shorter than with the brake device 27. In the automatic brake control of this embodiment, by simultaneously turning on the regenerative brake and the friction brake, it is possible to shorten the time from the occurrence of sudden steering until the generation of braking force. Furthermore, while the regenerative brake has excellent responsiveness, the friction brake is superior in terms of sustainability, etc. Therefore, by turning on both brakes in an emergency, the regenerative brake first shortens the free-running distance, and then the friction brake, which operates with a delay, compensates for the subsequent braking force, thereby suitably eliminating concerns about the sustainability of the regenerative brake.

[0052] By waiting for the friction brake to operate before stopping the regenerative brake, it is possible to prevent an excessive drop in braking force during automatic brake control. In addition, stopping the regenerative brake is also preferable in terms of preventing excessive charging.

[0053] In the automatic brake control shown in this embodiment, the regenerative braking force is set according to the detected road surface conditions, etc. Because regenerative braking has high responsiveness, the braking force can increase suddenly when the automatic brake control starts. When a sudden steering operation is performed under slippery conditions such as when driving on a low μ road or turning, it is possible to suppress a rapid increase in braking force when generating braking force by automatic braking, and it is possible to effectively suppress disturbances in the behavior of the vehicle 10 during automatic braking.

[0054] <Other embodiments> The state transition process of Fig. 3 may be replaced by the state transition process of Fig. 8. Fig. 8 is a partial modification of Fig. 3, and the same processes as Fig. 3 are given the same step numbers and will not be described again.

[0055] 8, when the actual SOC is less than the upper limit value L1 and the brake device 27 is in a state where it can generate a frictional braking force equivalent to the required braking force PX (when both steps S203 and S204 are YES), it is determined in step S401 whether the vehicle speed is less than a predetermined threshold value Th. The threshold value Th is, for example, 10 km / h. If the vehicle speed is equal to or greater than the predetermined threshold value Th, the process is temporarily terminated. If the vehicle speed is less than the predetermined threshold value Th, the process proceeds to step S205, where a transition is made from a state in which the required braking force PX is generated by regenerative braking force and frictional braking force to a state in which the required braking force PX is generated by frictional braking force.

[0056] 5, when the brake device 27 is in a state where it can generate a frictional braking force equivalent to PX at timing ta3, if the actual SOC is less than upper limit L1 and the vehicle speed is equal to or greater than threshold Th, the state where the required braking force PX is generated by regenerative braking force and frictional braking force is maintained because the actual SOC has a margin up to the SOC upper limit and the vehicle speed is still high. Then, when the vehicle speed subsequently drops to threshold Th, a transition is made from the state where the required braking force PX is generated by regenerative braking force and frictional braking force to a state where the required braking force PX is generated by frictional braking force.

[0057] At the beginning of automatic brake control, the regenerative braking force of the traction motor 23 may be temporarily increased above its upper limit. Specifically, as shown in FIG. 9, when a braking force corresponding to the required braking force PX is generated by outputting a regenerative brake command and a friction brake command, the regenerative braking force is set to exceed the upper limit before the friction braking force begins to take effect. In this case, the upper limit of the regenerative braking force may be set using, for example, the torque characteristics of the traction motor 23, which define the relationship between the motor rotation speed (vehicle speed) and torque. The period during which the regenerative braking force exceeding the upper limit is generated may be a predetermined time.

[0058] This configuration allows the braking force equivalent to the required braking force PX to be generated as soon as possible after the start of automatic brake control. Also, by limiting the period during which the regenerative braking force exceeds the upper limit to a short period, an excessive increase in the SOC can be suppressed.

[0059] When automatic brake control is implemented, the magnitude of the required braking force PX may be changed between an initial period including the start of the automatic brake control and a subsequent period. Specifically, as shown in Fig. 10, during a first period T1 at the start of the automatic brake control, the required braking force PX of the automatic brake control is set to a forced braking force (e.g., 0.5 G) that is greater than the normal braking force (e.g., 0.3 G), and during a subsequent second period T2, the required braking force PX of the automatic brake control is reduced to the normal braking force. In this case, the first period T1 may be transitioned to the second period T2, for example, when the vehicle speed falls below a predetermined value.

[0060] In the above embodiment, when it is determined that sudden steering has occurred, the SOC upper limit value is increased from the normal upper limit value L1 to the upper limit value L2. However, if the sudden steering is caused by the driver losing consciousness, charging of the battery 21 that exceeds the upper limit value L2 may be permitted.

[0061] Specifically, in step S107 of FIG. 2, the process of raising the SOC upper limit shown in FIG. 11 may be performed. In step S501 of FIG. 11, it is determined whether the driver has lost consciousness. At this time, an image of the driver captured by the driver camera 36 is analyzed, and it is determined from the analysis result whether the driver has lost consciousness. If the driver has not lost consciousness, the process proceeds to step S502, where the upper limit L2 is increased to "L21." If the driver has lost consciousness, the process proceeds to step S503, where the upper limit L2 is increased to "L22." Here, the upper limit L22 when the driver has lost consciousness is greater than the upper limit L21 when the driver has not lost consciousness (L22>L21).

[0062] When sudden steering is performed while the driver is unconscious, the driver cannot be expected to perform any operation (steering or braking), which can be said to be a situation of even greater urgency. In this regard, the above-described configuration makes it possible to implement appropriate automatic brake control when sudden steering is performed while the driver is unconscious.

[0063] After the automatic brake control due to sudden steering has started, the automatic brake control may be terminated or the braking force of the automatic brake control may be reduced if the driver performs a return operation to return the steering wheel in the opposite direction to the sudden steering. Specifically, the driving assistance ECU 20 may execute the automatic brake process shown in Figure 12. Figure 12 is a partial modification of Figure 2, and the same steps as in Figure 2 are assigned the same step numbers and their description will be omitted.

[0064] In Fig. 12, after the braking flag is set with the start of automatic brake control, it is determined in step S601 whether or not a corrective steering operation (returning operation) has been performed. Specifically, it is determined whether or not a corrective steering operation has been performed in the direction opposite to the steering direction of the sudden steering, based on detection information from the steering sensor 33. If it is determined in step S601 that a corrective steering operation has been performed, the process proceeds to step S114. In this case, the automatic brake control is released, the SOC upper limit value is returned, and the braking flag is cleared (steps S114 to S116).

[0065] When the process proceeds to step S114 due to a corrective steering operation of the steering wheel, the required braking force PX may be changed so as to reduce the braking force of the automatic brake control in step S114, instead of canceling the automatic brake control. In this case, the automatic brake control continues, so the braking flag may be maintained in the set state.

[0066] In the above embodiment, when it is determined that sudden steering has been performed, the automatic brake control is performed by performing regenerative control of the travel motor 23 and operation control of the brake device 27. However, the automatic brake control may be performed by performing only one of the regenerative control of the travel motor 23 and operation control of the brake device 27. However, in view of the fact that regenerative braking by the travel motor 23 has higher responsiveness than friction braking by the brake device 27, it is preferable to perform regenerative control of the travel motor 23.

[0067] When automatic braking control is initiated in response to sudden steering, quick charging, which charges the vehicle at a higher rate per unit time than normal charging, may be temporarily permitted to increase the rate of increase (rise) of regenerative braking force. Quick charging also causes a sudden rise in the actual SOC of the battery 21, but by raising the SOC upper limit, it is possible to prevent regeneration from being lost during automatic braking.

[0068] In the above embodiment, the SOC upper limit is increased from L1 to L2 to allow charging of the battery 21 beyond its SOC upper limit (normal upper limit L1) when automatic brake control is performed. However, if charging beyond L1 is permitted, it is also possible to disable the upper limit limiter function and allow charging up to the full capacity of the battery 21. In particular, it is advisable to disable the limiter function in situations of high urgency, such as sudden steering while the driver is unconscious.

[0069] To efficiently recover regenerative power, a configuration is envisioned in which the SOC upper limit of the battery 21 is temporarily increased when the vehicle 10 travels downhill. In this configuration, when automatic braking control is performed in response to sudden steering, charging of the battery 21 may be permitted to a range exceeding the SOC upper limit (downhill upper limit) increased when the vehicle 10 travels downhill. Specifically, in step S107 of FIG. 2 , the driving assistance ECU 20 sets the upper limit L2 to a value higher than the SOC upper limit increased when the vehicle 10 travels downhill. When traveling downhill, charging of the battery beyond the normal SOC upper limit is permitted to increase the amount of regenerative energy recovered. When traveling abruptly, charging of the battery beyond the normal SOC upper limit is permitted to avoid danger to the vehicle 10. The degree of urgency and frequency of occurrence differ between traveling downhill and sudden steering. In light of these circumstances, the configuration shown in this modification is preferable for improving the safety of the vehicle 10 and protecting the battery 21.

[0070] When automatic braking control is performed in response to sudden steering, the vehicle's electrical loads, such as the air conditioner, may be forcibly driven to forcibly consume the power stored in the battery 21. Forcing the power consumption reduces the chance that the actual SOC of the battery 21 exceeds the SOC upper limit. This is also preferable in terms of preventing regeneration from being invalidated during automatic braking control.

[0071] When the SOC upper limit of the battery 21 is increased at the start of automatic brake control, it is preferable to take the temperature of the battery 21 into consideration.

[0072] In the above embodiment, sudden steering is determined based on the steering jerk, but the present invention is not limited to this. It may be possible to determine sudden steering based on the steering speed or acceleration. It is also possible to determine sudden steering based on a change in the behavior of the vehicle 10 (for example, a change in yaw).

[0073] A switch may be provided to switch between a mode in which automatic braking is possible and a mode in which automatic braking is not possible, allowing the driver to select either mode as desired.

[0074] As the friction brake device, instead of the hydraulic brake device 27, an electromagnetically driven brake device can also be used.

[0075] The automatic brake control shown in the above embodiment may be applied to an electric vehicle (HEV, PHEV) that uses both a traction motor and an engine, or may be applied to an internal combustion engine vehicle (ICE).

[0076] The controller and methods described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the controller and methods described herein may be implemented by a special-purpose computer configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the controller and methods described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0077] The above disclosure corresponds to the following configurations. [Configuration 1] The present invention is applied to a vehicle (10) equipped with a braking force generating device (23, 27) capable of generating braking force without the driver's brake operation, a sudden steering determination unit that determines whether sudden steering has been performed in the vehicle; a brake control unit that generates a braking force by controlling the braking force generating device based on a determination result that the sudden steering has been performed; A vehicle control device (20) comprising: [Configuration 2] the vehicle is an electric vehicle that can travel by being driven by a traction motor (23), The vehicle control device according to configuration 1, wherein when it is determined that the sudden steering has been performed, the brake control unit controls the traction motor to a regenerative state so as to generate braking force using the traction motor as the braking force generating device. [Configuration 3] The vehicle is equipped with a friction brake device (27), The vehicle control device according to configuration 2, wherein when it is determined that the sudden steering has been performed, the brake control unit controls the traction motor to a regenerative state and commands the operation of the friction brake device so as to generate braking force using the traction motor and the friction brake device as the braking force generating device. [Configuration 4] a braking force determination unit that determines a generation state of a friction braking force in the friction brake device after starting control of the travel motor and the friction brake device based on the determination result that the sudden steering has been performed, The vehicle control device according to configuration 3, wherein the brake control unit transitions from a first state in which braking force is generated by the driving motor and the friction brake device to a second state in which braking force is generated by the friction brake device, based on the generation state of the friction braking force determined by the braking force determination unit. [Configuration 5] the vehicle includes a battery (21) that supplies power to the driving motor, and the battery can be charged using regenerative power from the driving motor, while an upper SOC limit value is set as an upper limit of the SOC of the battery; The vehicle control device according to any one of configurations 2 to 4, further comprising a permission unit that permits charging of the battery exceeding the SOC upper limit value when the driving motor is controlled to a regenerative state based on the determination result that the sudden steering has been performed. [Configuration 6] the vehicle includes a friction brake device (27) and a battery (21) that supplies power to the traction motor, and the battery can be charged using regenerative power from the traction motor, while an upper SOC limit value is set as an upper limit of the SOC of the battery; a permission unit that permits charging of the battery exceeding the SOC upper limit value when the driving motor is controlled to a regenerative state based on the determination result that the sudden steering has been performed; The brake control unit When it is determined that the sudden steering has been performed, in order to generate a braking force using the traveling motor and the friction brake device as the braking force generating device, the traveling motor is controlled to a regenerative state and an operation of the friction brake device is commanded; The vehicle control device according to configuration 2 further includes, in a situation where the permission unit permits charging of the battery in excess of the SOC upper limit value, transitioning from a first state in which braking force is generated by the traction motor and the friction brake device to a second state in which braking force is generated by the friction brake device, based on the SOC of the battery exceeding the SOC upper limit value and friction braking force being generated by the friction brake device. [Configuration 7] an SOC exceedance determination unit that determines, when the driving motor is controlled to a regenerative state based on the determination result that the sudden steering has been performed, that the SOC of the battery has exceeded the SOC upper limit due to regeneration of the driving motor; The vehicle control device according to configuration 5 or 6, further comprising a regeneration limiting unit that limits regenerative power generation of the traction motor when the SOC excess determination unit determines that the SOC of the battery has exceeded the SOC upper limit value and the brake control unit cancels operation of the braking force generating device. [Configuration 8] a loss of consciousness determination unit that, when it is determined that the sudden steering has been performed, determines that the driver has lost consciousness as a cause of the sudden steering; The permission unit When it is determined that the sudden steering has been performed, the SOC upper limit value is switched from a first upper limit value under normal conditions to a second upper limit value higher than the first upper limit value, and by this switching, charging of the battery exceeding the first upper limit value is permitted. The vehicle control device according to any one of configurations 5 to 7, further comprising: when the loss of consciousness determination unit determines that the driver has lost consciousness, allowing charging of the battery exceeding the second upper limit value. [Configuration 9] In the vehicle, the SOC upper limit value is temporarily increased when traveling downhill, The vehicle control device according to any one of configurations 5 to 8, wherein the permission unit permits charging of the battery within a range exceeding the SOC upper limit value that is increased when the vehicle is traveling downhill when it is determined that the sudden steering has been performed. [Configuration 10] a regenerative braking force upper limit value is set as the upper limit of the braking force generated when the traction motor is in a regenerative state, The brake control unit When a braking force is to be generated based on the determination result that the sudden steering has been performed, a required braking force is determined as the braking force; The vehicle control device according to any one of configurations 2 to 9, wherein, at the beginning of generating a braking force corresponding to the requested braking force, generation of a regenerative braking force that exceeds the regenerative braking force upper limit value is temporarily permitted. [Configuration 11] The vehicle control device according to any one of configurations 2 to 10, wherein the brake control unit determines the regenerative braking force generated by putting the traction motor into a regenerative state based on at least one of a road surface condition of a road on which the vehicle is traveling and a turning state of the vehicle. [Configuration 12] 12. The vehicle control device according to any one of configurations 1 to 11, wherein the brake control unit terminates the control of the braking force generation device on condition that the driver performs a brake operation after starting control of the braking force generation device based on the determination result that the sudden steering has been performed. [Configuration 13] The vehicle control device according to any one of configurations 1 to 12, wherein the brake control unit terminates control of the braking force generation device or reduces the braking force on the condition that a return operation is performed to return the steering wheel in a direction opposite to the sudden steering after starting control of the braking force generation device based on the determination result that the sudden steering has been performed. [Explanation of symbols]

[0078] 10...vehicle, 20...driving assistance ECU (vehicle control device), 23...travel motor (braking force generating device), 27...brake device (braking force generating device).

Claims

1. The present invention is applied to a vehicle (10) equipped with a braking force generating device (23, 27) capable of generating braking force without the driver's brake operation, a sudden steering determination unit that determines whether sudden steering has been performed in the vehicle; a brake control unit that generates a braking force by controlling the braking force generating device based on a determination result that the sudden steering has been performed; A vehicle control device (20) comprising:

2. The present invention is applied to a vehicle (10) equipped with a braking force generating device (23, 27) capable of generating braking force without the driver's brake operation, The processor abrupt steering determination process for determining whether abrupt steering has been performed on the vehicle; a brake control process for generating a braking force by controlling the braking force generating device based on the determination result that the sudden steering has been performed; A vehicle control program that executes the above.

3. The present invention is applied to a vehicle (10) equipped with a braking force generating device (23, 27) capable of generating braking force without the driver's brake operation, determining that a sudden steering has been performed on the vehicle; a vehicle control method for controlling the braking force generating device to generate braking force, based on the determination result that the sudden steering has been performed;

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