JP2013241147A - Braking force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking force control device capable of improving the operability of a vehicle.SOLUTION: A braking force control device 1 includes a braking device 8 capable of individually imparting a braking force to each wheel 3 of a vehicle 2, and a controller 9 for imparting a braking force to the right and left wheels 3 of the vehicle 2 by controlling the braking device 8 during the K-turn steering of the vehicle 2. The controller 9 changes a braking force imparted to the right and left wheels 3 during the K-turn steering of the vehicle 2 on the basis of the possibility of contact between the vehicle 2 and an object around the vehicle 2 and a deviation between the target yaw rate of the vehicle 2 and the actual yaw rate of the vehicle 2. Consequently, the braking force control device 1 can improve the operability of the vehicle 2.

Description

  The present invention relates to a braking force control device.

  As a conventional braking force control device mounted on a vehicle, for example, Patent Document 1 discloses a behavior of a vehicle in which a braking force is applied to a turning inner front wheel of the vehicle when a steering wheel is returned in a counter-steer state. A control device is disclosed. This vehicle behavior control apparatus determines whether or not the counter steer has been performed according to the magnitude relationship between the target yaw rate and the actual yaw rate.

JP 2001-088672 A

  By the way, the vehicle behavior control device described in Patent Document 1 described above has room for further improvement in consideration of vehicle operability at the time of turnback steering (counter steering), for example.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a braking force control device capable of improving the operability of a vehicle.

  In order to achieve the above object, a braking force control device according to the present invention controls a braking device capable of individually applying a braking force to each wheel of the vehicle, and the braking device at the time of turnback steering of the vehicle, A control device that applies braking force to the left and right wheels of the vehicle, the control device being capable of contacting the vehicle with an object around the vehicle, the target yaw rate of the vehicle, and the actual vehicle Based on the deviation from the yaw rate, the braking force applied to the left and right wheels at the time of turnback steering of the vehicle is changed.

  Further, in the braking force control device, the control device is an index indicating that the vehicle is in an understeer state, which is determined according to a deviation between the target yaw rate and the actual yaw rate. When the drift state is greater than a preset drift state determination threshold, the vehicle is turned back compared to the case where there is no possibility of contact or the drift state is equal to or less than the drift state determination threshold. The braking force applied to the left and right wheels during steering can be made relatively small.

  Further, in the braking force control device, the drift state converts a deviation between the target yaw rate and the actual yaw rate into a steering angle, and a negative value and an understeer during oversteering regardless of the turning direction of the vehicle. The time can be calculated to be a positive value.

  Further, in the braking force control device, the control device changes the end determination threshold value for determining the end of the control for applying the braking force to the left and right wheels when the vehicle is turned back and forth. It is possible to change the braking force applied to the wheels.

  In the braking force control device, the control device changes the control amount of the control for applying the braking force to the left and right wheels at the time of turnback steering of the vehicle, thereby applying the braking force to the left and right wheels. Can be changed.

  The braking force control device according to the present invention has an effect that the operability of the vehicle can be improved.

FIG. 1 is a schematic configuration diagram of a vehicle to which a braking force control device according to an embodiment is applied. FIG. 2 is a flowchart illustrating an example of time threshold setting control by the ECU of the braking force control apparatus according to the embodiment. FIG. 3 is a schematic block diagram illustrating control amount calculation by the ECU of the braking force control apparatus according to the embodiment. FIG. 4 is a schematic diagram illustrating an example of control by the ECU of the braking force control apparatus according to the embodiment.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

[Embodiment]
1 is a schematic configuration diagram of a vehicle to which a braking force control device according to an embodiment is applied, FIG. 2 is a flowchart for explaining an example of time threshold setting control by an ECU of the braking force control device according to the embodiment, and FIG. FIG. 4 is a schematic block diagram for explaining control amount calculation by the ECU of the braking force control apparatus according to the embodiment, and FIG. 4 is a schematic diagram for explaining an example of control by the ECU of the braking force control apparatus according to the embodiment. .

The present embodiment is typically applied to a vehicle and has the following components.
(1) Sensors (for example, a wheel speed sensor, a rudder angle sensor, a yaw rate sensor, a lateral acceleration sensor, etc.) necessary for the turning steering specific control.
(2) Sensors necessary for contact determination (for example, millimeter wave radar, wheel speed sensor, etc.).
(3) An arithmetic device (for example, ECU) that performs contact determination.
(4) A required hydraulic pressure calculation device (for example, ECU) for turn-back steering specific control.
(5) A device that realizes the required hydraulic pressure (for example, a brake actuator).

  And this embodiment can improve the operativity of a vehicle according to a condition by reflecting contact possibility in switchback steering specific control by said component.

  A braking force control apparatus 1 according to the present embodiment is a braking control system that is mounted on a vehicle 2 and brakes the vehicle 2 as shown in FIG. The braking force control apparatus 1 is typically a system that stabilizes the behavior of the vehicle 2 by controlling the braking force generated on the wheels 3 of the vehicle 2. The vehicle 2 includes, as wheels 3, a left front wheel (left front wheel 3) 3FL, a right front wheel (right front wheel 3) 3FR, a left rear wheel (left rear wheel 3) 3RL, and a right rear wheel (right rear side). The wheel 3) is provided with 3RR, but these are simply referred to as the wheel 3 when it is not necessary to separate them.

  Specifically, the braking force control device 1 may be referred to as a steering device 4, an accelerator pedal 5, a power source 6, a brake pedal 7, a braking device 8, and an electronic control device (hereinafter referred to as “ECU”) as a control device. ) 9 and the like. In the vehicle 2, the power source 6 generates power (torque) according to the operation of the accelerator pedal 5 by the driver, and this power is transmitted to the wheels 3 through a power transmission device (not shown). Generate driving force. In addition, the vehicle 2 generates a braking force on the wheels 3 by operating the braking device 8 according to the operation of the brake pedal 7 by the driver.

  The steering device 4 steers the left front wheel 3FL and the right front wheel 3FR as steering wheels. The steering device 4 includes a steering wheel 10 that is a steering operator by a driver, and a turning angle imparting mechanism 11 that is driven by a steering operation of the steering wheel 10. For example, a so-called rack and pinion mechanism including a rack gear and a pinion gear can be used as the turning angle imparting mechanism 11, but the present invention is not limited thereto.

  The power source 6 is a driving power source such as an internal combustion engine or an electric motor. The vehicle 2 may be any of a hybrid vehicle having both an internal combustion engine and an electric motor as a driving power source, a combined vehicle having an internal combustion engine but no electric motor, and an EV vehicle having an electric motor and no internal combustion engine. The vehicle of the form may be sufficient. The braking device 8 can individually adjust the braking force generated on each wheel 3 of the vehicle 2.

  The braking device 8 is a variety of hydraulic brake devices in which brake oil, which is a working fluid, is filled in a hydraulic path connected from the master cylinder 12 to the wheel cylinder 14 via the brake actuator 13. In the braking device 8, the hydraulic braking unit 15 operates according to the braking pressure supplied to the wheel cylinder 14 to generate a pressure braking force on the wheel 3. The brake device 8 basically has the master cylinder 12 (operating pressure) applied to the brake oil by the master cylinder 12 according to the pedal depression force (operating force) acting on the brake pedal 7 when the driver operates the brake pedal 7. Is granted. In the braking device 8, the hydraulic braking unit 15 is activated by a pressure corresponding to the master cylinder pressure acting as a wheel cylinder pressure (braking pressure) in each wheel cylinder 14. Each hydraulic braking unit 15 has a brake pad abutting against and pressed against the disk rotor, whereby a predetermined rotational resistance force according to the wheel cylinder pressure acts on the disk rotor rotating together with the wheel 3. A braking force can be applied to the wheel 3 rotating integrally therewith. During this time, in the braking device 8, the wheel cylinder pressure is appropriately adjusted by the brake actuator 13 according to the driving state.

  Here, the brake actuator 13 individually adjusts the braking force generated in each wheel 3 by individually increasing, reducing, and maintaining the wheel cylinder pressure independently of the four wheels. The brake actuator 13 is provided on the hydraulic path of the brake oil that connects the master cylinder 12 and the wheel cylinder 14, and increases or decreases the hydraulic pressure in each wheel cylinder 14 by control by the ECU 9 separately from the brake operation of the brake pedal 7. The braking force applied to each wheel 3 is controlled. The brake actuator 13 includes, for example, a plurality of pipes, an oil reservoir, an oil pump, each hydraulic pipe connected to each wheel cylinder 14 provided on each wheel 3, and the hydraulic pressure of each hydraulic pipe is increased, reduced, and held, respectively. This is configured to include a plurality of solenoid valves and the like, and is controlled by the ECU 9. The brake actuator 13 functions as a working fluid pressure adjusting unit that transmits the hydraulic pressure (master cylinder pressure) in the hydraulic piping as it is, or pressurizes and depressurizes it to each wheel cylinder 14 to be described later in accordance with a control command of the ECU 9.

  During normal operation, the brake actuator 13 is driven by, for example, an oil pump or a predetermined electromagnetic valve in accordance with a control command from the ECU 9, so that the wheel cylinder 14 is operated according to the amount of operation (depression amount) of the brake pedal 7 by the driver. It is possible to regulate the wheel cylinder pressure acting on the cylinder. Further, the brake actuator 13 is configured so that, for example, an oil pump or a predetermined electromagnetic valve is driven in accordance with a control command of the ECU 9 in order to execute control or the like for stabilizing the behavior of the vehicle 2 as will be described later. It is possible to operate in a pressure increasing mode in which the wheel cylinder pressure acting on the cylinder 14 is increased, a holding mode in which the wheel cylinder pressure is maintained substantially constant, a pressure reducing mode in which pressure is reduced. The brake actuator 13 can set the mode individually for each wheel cylinder 14 of each wheel 3 according to the traveling state of the vehicle 2 under the control of the ECU 9. That is, the brake actuator 13 can individually adjust the braking force acting on each wheel 3 according to the traveling state of the vehicle 2 regardless of the operation of the brake pedal 7 by the driver. Thereby, the braking device 8 can apply a braking force to each wheel 3 individually.

  The ECU 9 controls driving of each part of the vehicle 2 and includes an electronic circuit mainly composed of a known microcomputer including a CPU, a ROM, a RAM, and an interface. The ECU 9 includes, for example, each wheel speed sensor 16 that detects the rotational speed of each wheel 3, a yaw rate sensor 17 that detects the yaw rate of the vehicle 2, a steering angle sensor 18 that detects the steering angle of the steering device 4, and the vehicle body of the vehicle 2. Various sensors and detection devices attached to various parts of the vehicle 2 such as a lateral acceleration sensor 19 for detecting the generated lateral acceleration (direction intersecting (orthogonal) with the traveling direction) are electrically connected to respond to the detection result. The electrical signal is input. The ECU 9 drives each part of the vehicle 2 such as the power source 6 and the brake actuator 13 of the braking device 8 by executing a stored control program based on various input signals and various maps input from various sensors. A signal is output to control these driving operations.

  Then, the ECU 9 of this embodiment controls the brake actuator 13 according to the traveling state of the vehicle 2 and individually increases or decreases the wheel cylinder pressures of the wheel cylinders 14 provided on the wheels 3, respectively. By controlling the power individually, the behavior stabilization function of the vehicle 2 can be realized.

  For example, as a control for stabilizing the behavior of the vehicle 2, the ECU 9 controls the braking device 8 when the vehicle 2 is turned back (counter steer) and applies a turning force to the left and right wheels 3 of the vehicle 2. Control etc. can be executed. Thereby, the braking force control apparatus 1 can control the behavior of the vehicle 2 at the time of turnback steering.

  Here, the ECU 9 controls the braking device 8 in order to stabilize the vehicle behavior after the turn-back steering during the steering operation in which the turning direction is switched in a short time, that is, the turn-back steering. A predetermined braking torque (braking force) is applied to the vehicle 2 so as to decelerate the vehicle 2. That is, the turning-back steering specific control referred to here is deceleration control that applies a predetermined braking force to both the left and right wheels 3 during turning-back when the turning-back steering by the driver is detected and specified.

  By the way, in such a vehicle 2, for example, when there is a possibility that contact with an obstacle ahead in the traveling direction of the vehicle 2 cannot be avoided by the first steering, the driver turns back to avoid the obstacle. Steering (counter steer) may be performed. In such a case, the braking force control device 1 causes the ECU 9 to execute the switching steering specific control (hereinafter, simply referred to as “deceleration control”) and apply braking torque to both the left and right wheels 3. As a result, the steering performance of the vehicle 2 may be reduced, and there is room for further improvement in vehicle operability in this respect.

  In view of this, the ECU 9 of the present embodiment determines the possibility of contact between the vehicle 2 and an object around the vehicle 2 (hereinafter, also referred to as “peripheral object”), and the target yaw rate (hereinafter referred to as “target”). ) ”And the actual yaw rate of the vehicle 2 (hereinafter, also referred to as“ actual yaw rate ”), the control applied to the left and right wheels 3 when the vehicle 2 is turned back and forth. Change the power (braking torque). As a result, the braking force control device 1 improves the operability of the vehicle 2.

  Here, the ECU 9 changes the end determination threshold value for determining the end of the reverse steering specific control for applying the braking force to the left and right wheels 3 at the time of the reverse steering of the vehicle 2, for example. Change the braking force to be applied. For example, the ECU 9 may change the braking force applied to the left and right wheels 3 by changing the deceleration control amount itself of the turning steering specific control when the vehicle 2 is turned back.

  Specifically, as shown in FIG. 1, the braking force control device 1 of the present embodiment includes a millimeter wave radar 20 as a peripheral object detection device. In addition, the ECU 9 of the braking force control apparatus 1 according to the present embodiment is functionally conceptually configured with a switchback steering determination unit 21, a drift state calculation unit 22, a contact possibility determination unit 23, a control amount calculation unit 24, and a control. A start / end determination unit 25 and a braking force control unit 26 are provided.

The millimeter wave radar 20 is a detection device that detects a peripheral object of the vehicle 2 that is the host vehicle, and detects a relative physical quantity indicating a relative positional relationship between the detected vehicle 2 and the peripheral object. The peripheral objects detected by the millimeter wave radar 20 include obstacles ahead of the vehicle 2 in the traveling direction. The millimeter wave radar 20 is a peripheral object, for example, a preceding vehicle in the vicinity of the vehicle 2, a succeeding vehicle, a side vehicle, a passerby (pedestrian or bicycle) passing near the traveling path of the vehicle 2, or a vicinity of the traveling path of the vehicle 2. Detects a stationary object located in The millimeter wave radar 20 detects surrounding objects within a predetermined detection range with the vehicle 2 as the center. Here, for example, the millimeter wave radar 20 uses, as the relative physical quantity, at least the relative speed (m / s), the relative distance (m), the relative deceleration (m / s ² ), TTC ( It has a function of detecting at least one of Time-To-Collision: contact margin time (s) and the like. Here, TTC (hereinafter sometimes referred to as “relative time”) corresponds to the time until the vehicle 2 reaches the surrounding object, and the relative distance between the vehicle 2 and the surrounding object is converted according to the relative speed. It corresponds to the time. The millimeter wave radar 20 transmits an electromagnetic wave such as a millimeter wave, receives a reflected wave reflected by an object, and detects the relative physical quantity based on a time until the electromagnetic wave is transmitted and received. The millimeter wave radar 20 outputs the detected relative physical quantity to the ECU 9.

  The peripheral object detection device uses a radar using laser or infrared rays, a short-range radar such as an UWB (Ultra Wide Band) radar, an audible sound wave or an ultrasonic wave instead of the millimeter wave radar 20. You may use the image recognition apparatus etc. which calculate the said relative physical quantity etc. by analyzing the image data which imaged the running direction front of the own vehicle with imaging devices, such as a sonar and a CCD camera.

  The switchback steering determination unit 21 determines switchback steering that is a steering operation in which the turning direction is switched in a short time. The switchback steering determination unit 21 determines that the switchback steering has been performed based on, for example, the yaw rate of the vehicle 2 detected by the yaw rate sensor 17, the steering angle and the steering angular velocity detected by the steering angle sensor 18, and the like. As an example, the turn-back steering determination unit 21 determines that the turn-back steering is performed when any one, preferably all, of the following conditions (1) to (3) are satisfied.

(1) When the yaw rate generated when the vehicle 2 turns left is positive, the actual yaw rate is greater than a preset positive yaw rate setting value during the left turn of the vehicle 2, or the actual yaw rate is increased during the right turn. It is either smaller than a preset negative yaw rate set value.
(2) When the steering angle is STR, the steering angular speed is dSTR, and K is a positive correction coefficient, the correction steering angle represented by STR + K · dSTR is opposite to the actual turning direction of the vehicle 2.
(3) The absolute value of the difference between the target yaw rate and the actual yaw rate is smaller than a preset setting difference.

  The condition (1) is a condition indicating that a sudden turn is being performed. The condition (2) is used to determine the execution of the turn-back steering based on the steering angle using the fact that the operation of the steering wheel 10 is earlier than the actual yaw rate. Here, the detection timing of the turn-back steering is advanced by making a determination using the corrected steering angle in which the components of the steering angular velocity are taken in at an appropriate ratio. The condition (3) is that when the absolute value of the actual yaw rate is relatively large, the absolute value of the target yaw rate is decreased, and the absolute value of the difference between the target yaw rate and the actual yaw rate is reduced to some extent, the turn-back steering is performed. Is to be detected. If the absolute value of the target yaw rate decreases, the target yaw rate and the actual yaw rate will eventually be reversed. However, based on the above condition (3), the steering is switched back earlier than the case based on the reversal of the size. Can be detected.

  The ECU 9 sets the target yaw rate using various methods when the vehicle 2 is turning. The target yaw rate is calculated based on, for example, the steering angle of the vehicle 2 and the vehicle body speed (hereinafter sometimes referred to as “vehicle speed”). The steering angle of the vehicle 2 may be detected by the steering angle sensor 18. What is necessary is just to use what is estimated from the wheel speed of each wheel 3 which each wheel speed sensor 16 detects, but using what was detected by the vehicle speed sensor provided separately from each wheel speed sensor 16 is used. Also good. For example, the ECU 9 is generated in the vehicle 2 when it is assumed that the vehicle 2 is performing a predetermined circular turning motion from the steering angle and the vehicle speed based on detection results by the wheel speed sensors 16 and the steering angle sensor 18. The yaw rate is calculated and set as the target yaw rate.

  Further, the turnback steering determination unit 21 may determine that the turnback steering is performed by determining various conditions in addition to the above conditions (1) to (3).

  The drift state calculation unit 22 calculates a drift state. The drift state is typically an index indicating that the vehicle 2 is in an understeer state. The drift state is a parameter determined according to the deviation between the target yaw rate and the actual yaw rate. More specifically, in the drift state, the deviation between the target yaw rate and the actual yaw rate is converted into a steering angle, and regardless of the turning direction of the vehicle (own vehicle) 2, a negative value is obtained when oversteering, and a positive value when understeering. Is a parameter calculated to be The drift state calculation unit 22 is based on the target yaw rate calculated as described above according to the detection results by the wheel speed sensors 16 and the steering angle sensor 18 and the actual yaw rate according to the detection results by the yaw rate sensor 17. Calculate the drift state.

  The contact possibility determination unit 23 determines the contact possibility between the vehicle 2 and a surrounding object in the traveling direction. The contact possibility determination unit 23 determines the possibility of contact between the surrounding object in the traveling direction and the vehicle 2 based on the relative physical quantity indicating the relative positional relationship between the surrounding object and the vehicle 2 detected by the millimeter wave radar 20. To do. The contact possibility determination unit 23 determines “possibility of contact” as the relative physical quantity, for example, when the relative distance between the vehicle 2 and the surrounding object is equal to or less than a preset relative distance threshold. Further, the contact possibility determination unit 23 determines “possibility of contact” when, for example, the TTC (relative time) is equal to or less than a preset TTC threshold as the relative physical quantity. The contact possibility determination unit 23 performs the contact determination when the first steering operation is performed by the driver, for example. The relative distance threshold and the TTC threshold are set in advance based on actual vehicle evaluation and the like, and are stored in the storage unit of the ECU 9.

  The control amount calculation unit 24 calculates the deceleration control amount of the turn-back steering specific control (deceleration control). The control amount calculation unit 24 has a predetermined magnitude of braking force (braking torque) applied to the left and right wheels 3, typically the left front wheel 3FL and the right front wheel 3FR, which are steering wheels, during the turning steering specific control. The deceleration control amount for realizing is calculated. Here, the control amount calculation unit 24 calculates a wheel cylinder pressure required for the wheel 3 (hereinafter sometimes simply referred to as “required hydraulic pressure”) as the deceleration control amount.

  For example, the control amount calculation unit 24 calculates the required oil pressure to be relatively large so that the braking force applied during the turn-back steering specific control becomes relatively larger as the turning and the turn-back steering become steeper, for example. To do. Based on at least one of the target yaw rate, the actual yaw rate generated along with the turn, the steering angle of the turning-back steering, the steering angular speed of the turning-back steering, the control amount calculation unit 24, for example, The required oil pressure is increased as the local maximum value increases. It should be noted that the control amount calculation unit 24 can also make the magnitude of the braking force applied during the turning-back steering specific control constant, that is, make the required oil pressure during the turning-back steering specific control constant.

  The control start / end determination unit 25 performs the start determination and the end determination of the turn-back steering specific control. Here, the control start / end determination unit 25 first performs permission determination of the turn-back steering specific control before the start determination of the turn-back steering specific control.

  The permission determination of the return steering specific control is to determine whether or not the current state of the braking force control device 1 is a state in which the return steering specific control can be executed. For example, the control start / end determination unit 25 performs permission determination for the turning-back steering specific control based on whether or not various sensors are operating normally, whether or not the vehicle speed is equal to or higher than a predetermined value, and the like. For example, when the various sensors are operating normally and the vehicle speed is determined to be greater than or equal to a predetermined value, the control start / end determination unit 25 can execute the steering specific control by switching back the current state of the braking force control device 1. Is determined to be in the correct state, and the execution of the turning-back steering specific control is permitted.

  The control start / end determination unit 25 permits the start of the turnback steering specific control and then determines the start of the turnback steering specific control. For example, the control start / end determination unit 25 determines the start of the switchback steering specific control based on the determination result by the switchback steering determination unit 21. The control start / end determination unit 25 determines to start the reverse steering specific control when the reverse steering determination unit 21 determines that the reverse steering is performed.

  Then, the control start / end determination unit 25 performs the end determination of the reverse steering specific control after the reverse steering specific control is started. For example, the control start / end determination unit 25 determines the end of the turnback steering specific control based on the elapsed time since the turnback steering determination unit 21 determines that the turnback steering is performed. For example, when the control start / end determination unit 25 determines that the elapsed time from the determination that the reverse steering is performed by the reverse steering determination unit 21 exceeds a preset time threshold (end determination threshold), It is determined that the return steering specific control is to be ended. The end determination threshold value is set in advance based on actual vehicle evaluation and the like, and is stored in the storage unit of the ECU 9.

  The braking force control unit 26 controls the braking device 8 to control the braking force applied to the wheels 3. The braking force control unit 26 controls the braking force (braking torque) of each wheel 3 by controlling the brake actuator 13 of the braking device 8 and adjusting the wheel cylinder pressure of each wheel 3. The braking force control unit 26 controls the brake actuator 13 based on the required hydraulic pressure calculated by the control amount calculation unit 24 when the control start / end determination unit 25 determines the start of the turnback steering specific control. As a result, the braking force control unit 26 converges the actual wheel cylinder pressures of the left front wheel 3FL and the right front wheel 3FR to the required oil pressure, and a braking force (braking torque) having the same magnitude as the left front wheel 3FL and the right front wheel 3FR. Is granted. When the control start / end determination unit 25 determines the end of the return steering specific control, the braking force control unit 26 controls the brake actuator 13 and ends the reverse steering specific control.

  Then, the control start / end determination unit 25 of the present embodiment uses the contact possibility determined by the contact possibility determination unit 23 and the drift state calculated by the drift state calculation unit 22 when the vehicle 2 is turned back and forth. Based on this, the braking force applied to the left and right wheels 3 is changed by changing the time threshold value (end determination threshold value) for determining the end of the turn-back steering specific control. For example, when it is determined that there is a possibility of contact and it is determined that the drift state is greater than a preset drift state determination threshold, the control start / end determination unit 25 relatively shortens the time threshold. The drift state determination threshold is set in advance based on actual vehicle evaluation or the like, and is stored in the storage unit of the ECU 9.

  Here, an example of the time threshold setting control by the control start / end determination unit 25 will be described with reference to the flowchart of FIG. Note that these control routines are repeatedly executed at a control cycle of several ms to several tens of ms.

  The control start / end determination unit 25 includes the contact possibility determined by the contact possibility determination unit 23 and the drift state calculated by the drift state calculation unit 22 in a state where the turning steering specific control is started and continued. Based on the above, it is determined whether there is a possibility of contact (front contact unavoidable) and the drift state is larger than the drift state determination threshold DSth (ST1).

  When it is determined that there is no possibility of contact or the drift state is equal to or less than the drift state determination threshold value DSth (ST1: No), the control start / end determination unit 25 sets the time threshold value Tth to the normal value Tth (ST2). The process proceeds to ST4.

  On the other hand, when the control start / end determination unit 25 determines that there is a possibility of contact and the drift state is larger than the drift state determination threshold DSth (ST1: Yes), the time threshold Tth is smaller than the normal value Tth. The value Tth_c is set (ST3), and the process proceeds to ST4.

  The control start / end determination unit 25 determines whether or not the elapsed time from the determination that the reverse steering is performed by the reverse steering determination unit 21 has exceeded the time threshold Tth set in ST2 or ST3 (ST4). ). When it is determined that the elapsed time does not exceed the time threshold Tth (ST4: No), the control start / end determination unit 25 returns to ST1 and repeatedly executes the subsequent processing.

  When it is determined that the elapsed time has exceeded the time threshold value Tth (ST4: Yes), the control start / end determination unit 25 ends the return steering specific control (ST5), ends the current control cycle, and then continues to the next control cycle. Migrate to

  As a result, the control start / end determination unit 25 switches back when there is a possibility of contact and when the drift state is larger than the drift state determination threshold, that is, there is a possibility of contact and the vehicle 2 is in an understeer tendency. Steering specific control can be terminated early, and the braking force during turning-back steering of the vehicle 2 can be reduced. That is, the control start / end determination unit 25 can adjust the end timing of the turn-back steering specific control by changing the time threshold value used for the end determination of the turn-back steering specific control during the turn-back steering of the vehicle 2. In particular, the braking force applied to the left and right wheels 3 can be changed.

  Thereby, the ECU 9 has a possibility of contact, and when the drift state is larger than a preset drift state determination threshold, there is no possibility of contact, or when the drift state is equal to or less than the drift state determination threshold. As compared with the above, the braking force applied to the left and right wheels 3 when the vehicle 2 is steered back can be relatively reduced. Therefore, the ECU 9 has a possibility of contact, and when the drift state is larger than the drift state determination threshold, that is, there is a possibility of contact, and there is a possibility that the steering performance of the vehicle 2 is deteriorated by the turnback steering specific control. In this case, it is possible to end the turning-back steering specific control at an early stage and reduce the braking force at the time of turning-back steering of the vehicle 2. As a result, the braking force control device 1 can prioritize the vehicle operability over the deceleration performance by the turn-back steering specific control (deceleration control) when there is a possibility of contact between the vehicle 2 and the surrounding object.

  Further, the control amount calculation unit 24 of the present embodiment is based on the contact possibility determined by the contact possibility determination unit 23 and the drift state calculated by the drift state calculation unit 22 when the vehicle 2 is turned back. The braking force applied to the left and right wheels is changed by changing the required hydraulic pressure that is the control amount of the turning-back steering specific control. For example, the control amount calculation unit 24 reduces the required oil pressure when there is a possibility of contact and the drift state is relatively large.

  Here, an example of calculation of the required oil pressure by the control amount calculation unit 24 will be described with reference to the block diagram of FIG. The control amount calculation unit 24 includes, for example, a gain setting unit 24a and a multiplier 24b.

  The gain setting unit 24a receives the contact possibility information determined by the contact possibility determination unit 23 and the drift state calculated and created from the deviation between the target yaw rate and the actual yaw rate by the drift state calculation unit 22. . The gain setting unit 24a sets a control gain based on the input contact possibility information and the drift state.

  The gain setting unit 24a sets the control gain based on, for example, the control gain map m illustrated in FIG. In the control gain map m, the horizontal axis represents the drift state, and the vertical axis represents the control gain. The control gain map m describes the relationship among the drift state, contact possibility, and control gain. The control gain map m is stored in the storage unit of the ECU 9 after the relationship between the drift state, the contact possibility, and the control gain is set in advance based on actual vehicle evaluation and the like. In the control gain map m, when the drift state is relatively large, the control gain L2 when there is a contact possibility is relatively smaller than the control gain L1 when there is no contact possibility. Is set to Based on the control gain map m, the gain setting unit 24a calculates a control gain from the input contact possibility information and the drift state. As a result, for example, when there is a possibility of contact and the drift state is relatively large, the gain setting unit 24a can set the control gain relatively small. The gain setting unit 24a inputs the set control gain to the multiplier 24b.

  In the present embodiment, the gain setting unit 24a has been described as calculating and setting the control gain using the control gain map m, but the present embodiment is not limited to this. For example, the gain setting unit 24a may calculate and set the control gain based on a mathematical model corresponding to the control gain map m.

  As described above, the multiplier 24b receives the base required oil pressure calculated based on the target yaw rate, the actual yaw rate, the steering angle of the turnback steering, the steering angular speed, and the control gain set by the gain setting unit 24a. . The multiplier 24b multiplies the input base required hydraulic pressure by the control gain, thereby calculating the required hydraulic pressure of the control wheel as the final deceleration control amount, and outputs it to the brake actuator 13 or the like.

  As a result, the control amount calculation unit 24 increases the control gain when there is a possibility of contact and the drift state is larger than the drift state determination threshold, that is, when there is a possibility of contact and the vehicle 2 is in an understeer tendency. The required oil pressure can be set relatively low by setting it to be relatively small, and the braking force at the time of turning-back steering of the vehicle 2 can be reduced. That is, the control amount calculation unit 24 can directly change the braking force applied to the left and right wheels 3 by changing the required hydraulic pressure itself that is the deceleration control amount when the vehicle 2 is turned back.

  Thereby, the ECU 9 has a possibility of contact, and when the drift state is larger than a preset drift state determination threshold, there is no possibility of contact, or when the drift state is equal to or less than the drift state determination threshold. As compared with the above, the braking force applied to the left and right wheels 3 when the vehicle 2 is steered back can be relatively reduced. Therefore, the ECU 9 has a possibility of contact, and when the drift state is larger than the drift state determination threshold, that is, there is a possibility of contact, and there is a possibility that the steering performance of the vehicle 2 is deteriorated by the turnback steering specific control. In this case, the braking force when the vehicle 2 is turned back can be reduced. As a result, the braking force control device 1 can prioritize the vehicle operability over the deceleration performance by the turn-back steering specific control (deceleration control) when there is a possibility of contact between the vehicle 2 and the surrounding object.

  In addition, as illustrated in FIG. 4, the ECU 9 performs other vehicle stabilization / anti-overturn control, as an example, target yaw rate follow-up control, in addition to the turning-back steering specific control, as control for stabilizing the behavior of the vehicle 2. May be possible. In this target yaw rate follow-up control, the required hydraulic pressure of each wheel 3 is calculated so that the actual yaw rate approaches the target yaw rate, and the brake actuator 13 is controlled based on the calculated required hydraulic pressure to control the actual wheel cylinder pressure of the wheel 3. Is controlled to cause the actual yaw rate to follow the target yaw rate by adjusting the braking force of each wheel 3 by converging to the required oil pressure.

  In this case, the ECU 9 is based on the rudder angle detected by the rudder angle sensor 18, the yaw rate detected by the yaw rate sensor 17, the lateral acceleration (G) detected by the lateral acceleration sensor 19, the wheel speed detected by each wheel speed sensor 16, and the like. Thus, as described above, the permission determination, start determination, and end determination of the turn-back steering specific control are performed. In addition, the ECU 9 is based on the rudder angle detected by the rudder angle sensor 18, the yaw rate detected by the yaw rate sensor 17, the lateral acceleration (G) detected by the lateral acceleration sensor 19, the wheel speed detected by each wheel speed sensor 16, and the like. The vehicle stabilization / overturn-resistant control permission / start / end determination is also performed. The permission determination for the vehicle stabilization / overturning resistance control is substantially the same as the permission determination for the turn-back steering specific control described above. The start / end determination of the vehicle stabilization / anti-overturn control may be performed based on, for example, the deviation between the target yaw rate and the actual yaw rate. Then, the ECU 9 calculates a required hydraulic pressure (control amount) in the turn-back steering specific control and a required hydraulic pressure (control amount) in the vehicle stabilization / anti-overturn control. For example, the ECU 9 may calculate the required hydraulic pressure in the vehicle stabilization / anti-overturn control based on the deviation between the target yaw rate and the actual yaw rate. Then, the ECU 9 selects, for each wheel 3, the maximum value of the required hydraulic pressure (control amount) for the turning-back steering specific control and the required hydraulic pressure (control amount) for the vehicle stabilization / anti-overturn control, and the brake actuator It may be output to 13 etc.

  The braking force control device 1 configured as described above performs predetermined steering torque (braking force) to both the left and right wheels 3 during the turning by executing the turning steering specific control during the turning turning of the vehicle 2. It is possible to decelerate the vehicle 2 and stabilize the vehicle behavior after the turn-back steering. For example, if the braking force control device 1 applies braking torque to both the left and right wheels 3 (the left front wheel 3FL and the right front wheel 3FR), for example, compared to a case where the braking torque is applied only to the front wheels inside the vehicle turning. Thus, the limit of deceleration due to braking can be increased.

  In addition, the braking force control device 1 controls the right and left wheels 3 when the vehicle 2 is turned back and forth based on the possibility of contact between the vehicle 2 and surrounding objects and the deviation between the target yaw rate and the actual yaw rate. By changing the power, the operability of the vehicle 2 can be improved according to the situation. For example, the braking force control device 1 has a possibility of contact, and when the drift state is larger than the drift state determination threshold value, that is, there is a possibility of contact, and the steering performance of the vehicle 2 is deteriorated by the turn-back steering specific control. When there is a possibility, the braking force applied to the left and right wheels 3 when the vehicle 2 is turned back is relatively reduced. Thereby, the braking force control apparatus 1 can give priority to the vehicle operability over the deceleration performance by the turn-back steering specific control (deceleration control) when there is a possibility of contact between the vehicle 2 and the surrounding object. In such a case, the operability of the vehicle 2 can be improved.

  According to the braking force control device 1 according to the embodiment described above, the braking device 8 that can individually apply the braking force to each wheel 3 of the vehicle 2 and the braking device 8 are controlled when the vehicle 2 is turned back. And an ECU 9 that applies braking force to the left and right wheels 3 of the vehicle 2. Based on the possibility of contact between the vehicle 2 and an object around the vehicle 2 and the deviation between the target yaw rate of the vehicle 2 and the actual yaw rate of the vehicle 2, the ECU 9 The braking force applied to the wheel 3 is changed.

  Therefore, the braking force control device 1 optimizes the braking force to be applied to the left and right wheels 3 based on the possibility of contact and the deviation between the target yaw rate and the actual yaw rate when the vehicle 2 is turned back. The operability can be improved, whereby both the deceleration performance and the steering performance can be achieved.

  The braking force control apparatus according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims.

  The braking device 8 described above may be one that applies braking force to each wheel individually using, for example, an engine (engine) brake by an internal combustion engine, or electric braking such as regenerative braking by a rotating electrical machine. The braking force may be individually applied to each wheel by using.

  In the above description, the control device has been described as being shared by the ECU 9, but is not limited thereto. For example, the control device may be configured separately from the ECU 9 and may exchange information such as a detection signal, a drive signal, and a control command with each other.

  Further, the control amount calculation unit 24 described above replaces the control gain with the wheel in the switchback steering specific control based on the contact possibility information and the drift state according to the deviation between the target yaw rate and the actual yaw rate. An initial pressure increase gradient of the cylinder pressure may be calculated and set. Even in this case, the control amount calculation unit 24 changes the initial pressure increase gradient based on the contact possibility and the drift state (deviation between the target yaw rate and the actual yaw rate), so The braking force applied to the wheel 3 can be changed.

  Further, the control start / end determination unit 25 described above is used for the start determination of the reverse steering specific control, in other words, the reverse steering determination when the contact possibility determination unit 23 determines that there is a possibility of contact. You may make it change a threshold value so that switchback steering specific control is hard to start.

  The ECU 9 described above changes the braking force applied to the left and right wheels 3 by changing the end determination threshold value for determining the end of the return steering specific control when the vehicle 2 is turned back. A configuration may be provided that does not include any one of the configuration in which the braking force applied to the left and right wheels 3 is changed by changing the control amount of the turning-back steering specific control.

DESCRIPTION OF SYMBOLS 1 Braking force control apparatus 2 Vehicle 3 Wheel 4 Steering apparatus 5 Accelerator pedal 6 Power source 7 Brake pedal 8 Braking apparatus 9 ECU (control apparatus)
DESCRIPTION OF SYMBOLS 13 Brake actuator 20 Millimeter wave radar 21 Return steering determination part 22 Drift state calculation part 23 Contact possibility determination part 24 Control amount calculation part 25 Control start / end determination part 26 Braking force control part

Claims (5)

A braking device capable of individually applying a braking force to each wheel of the vehicle;
A control device that controls the braking device and applies a braking force to the left and right wheels of the vehicle when the vehicle is turned back and forth;
The control device determines whether the left and right sides of the vehicle are turned back and forth based on a possibility of contact between the vehicle and an object around the vehicle and a deviation between a target yaw rate of the vehicle and an actual yaw rate of the vehicle. The braking force applied to the wheels of the vehicle is changed,
Braking force control device. The control device is preset with a drift state that is the index indicating that the vehicle is in an understeer state and is determined according to a deviation between the target yaw rate and the actual yaw rate. When it is larger than the drift state determination threshold, compared with the case where there is no possibility of contact, or when the drift state is equal to or less than the drift state determination threshold, it is given to the left and right wheels at the time of turnback steering of the vehicle. Make the braking force relatively small,
The braking force control apparatus according to claim 1. In the drift state, a deviation between the target yaw rate and the actual yaw rate is converted into a steering angle so that a negative value is obtained at the time of oversteering and a positive value at the time of understeering regardless of the turning direction of the vehicle. Calculated,
The braking force control apparatus according to claim 1 or 2. The control device changes the braking force applied to the left and right wheels by changing an end determination threshold value for determining the end of control for applying the braking force to the left and right wheels at the time of turning steering of the vehicle. To
The braking force control apparatus according to any one of claims 1 to 3. The control device changes a braking force to be applied to the left and right wheels by changing a control amount of a control to apply a braking force to the left and right wheels at the time of turning steering of the vehicle.
The braking force control apparatus according to any one of claims 1 to 4.

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