JP6940817B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device, and more particularly to a vehicle control device provided with a braking device capable of applying different braking forces to the left and right wheels.

Conventionally, there are known devices (such as electronic stability control) that control the behavior of a vehicle in a safe direction when the behavior of the vehicle becomes unstable due to slipping or the like. Specifically, it is known that when the vehicle is cornering or the like, it is detected that the vehicle has understeer or oversteer behavior, and an appropriate deceleration is applied to the wheels so as to suppress them. ing.

In addition, unlike the control for improving safety in a driving state where the behavior of the vehicle becomes unstable as described above, acceleration / deceleration linked to the steering wheel operation that operates from the daily driving area is automatically performed, and the limit is reached. A vehicle motion control device that reduces skidding in the driving region is known (see, for example, Patent Document 1). In particular, Patent Document 1 discloses a vehicle motion control device including a first mode for controlling acceleration / deceleration in the front-rear direction of the vehicle and a second mode for controlling the yaw moment of the vehicle. There is.

Japanese Patent No. 5143103

As described above, in the technique disclosed in Patent Document 1, in the second mode, control is performed to apply the yaw moment to the vehicle. The control for applying this yaw moment is not particularly problematic when the lateral acceleration of the vehicle is large, but when the lateral acceleration of the vehicle is small, the driver can easily feel that this control is intervening. It tends to give the driver a sense of discomfort (a relatively strong sense of control intervention). In particular, in the technique disclosed in Patent Document 1, a yaw moment corresponding to the size of the lateral jerk (corresponding to the steering speed) of the vehicle is applied to the vehicle, but the lateral jerk is large even when the lateral acceleration is small. In that case, the yaw moment becomes large, giving the driver a strong sense of control intervention.

The present invention has been made to solve the above-mentioned problems of the prior art, and in consideration of the magnitude of lateral acceleration in a vehicle control device that controls a brake device to apply a yaw moment to the vehicle. The purpose is to suppress giving a strong sense of intervention or discomfort to the driver by controlling the yaw moment.

In order to achieve the above object, the present invention is a vehicle control device including a steering device, a brake device capable of applying different braking forces to the left and right wheels, and a processor, wherein the processor is a vehicle. When the value corresponding to the turning state of is equal to or higher than the threshold value, the yaw moment in the opposite direction to the yaw rate generated in the vehicle is set, and the brake device is controlled so that the set yaw moment is generated in the vehicle. However, when the lateral acceleration generated in the vehicle is small, the threshold value is made larger than when it is not.
According to the present invention configured as described above, when the lateral acceleration generated in the vehicle is small, it is possible to make it difficult to execute the control for generating the yaw moment in the vehicle by increasing the threshold value. That is, the execution of the control can be suppressed. As a result, when the lateral acceleration is small, it is possible to appropriately suppress giving the driver a sense of discomfort due to the control that causes the yaw moment in the vehicle, specifically, a strong sense of control intervention. On the other hand, when the lateral acceleration is large, it is possible to execute a control for generating a yaw moment in the vehicle and appropriately secure the effect of this control.

Further, in the present invention, preferably, the processor is a braking device so as to generate a set yaw moment in the vehicle when the value corresponding to the turning state is equal to or higher than the threshold value and the steering angle of the steering device is decreasing. Is configured to control.
According to the present invention configured as described above, it is possible to appropriately execute the control for generating the yaw moment in the vehicle at the time of the turning back operation of the steering device. Therefore, the vehicle in the turning state can be quickly turned in the straight direction.

Further, in the present invention, preferably, the processor uses the steering speed acquired based on the detection value of the steering angle sensor that detects the steering angle of the steering device as the value according to the turning state, and the steering speed becomes equal to or higher than the threshold value. At that time, the target lateral jerk is set based on the steering speed and the vehicle speed, and the yaw moment is set based on the target lateral jerk.
According to the present invention configured as described above, a yaw moment having a magnitude corresponding to the speed of the steering operation of the driver can be applied in a direction of suppressing the turning of the vehicle, and the vehicle can be quickly operated according to the steering operation of the driver. The behavior can be stabilized.

Further, in the present invention, preferably, the processor is set as a value according to the turning state based on the actual yaw rate actually generated in the vehicle and the detection value of the steering angle sensor that detects the steering angle of the steering device. It is configured to use the rate of change of the difference from the target yaw rate and set the yaw moment based on the rate of change when the rate of change exceeds the threshold value.
According to the present invention configured in this way, when the steering wheel is operated on a low μ road such as a snow-packed road, the steering wheel is immediately changed in response to a sudden change in the yaw rate difference due to the response delay of the actual yaw rate. It is possible to apply a yaw moment in the direction of suppressing turning to the vehicle, and it is possible to quickly stabilize the vehicle behavior in response to the steering operation of the driver in a situation before the vehicle behavior becomes unstable.

In another aspect, in order to achieve the above object, the present invention is a vehicle control device including a steering device, a braking device capable of applying different braking forces to the left and right wheels, and a processor. , The processor sets the yaw moment in the opposite direction to the yaw rate generated in the vehicle based on the turning state of the vehicle, controls the braking device so as to generate the set yaw moment in the vehicle, and generates the yaw moment in the vehicle. When the lateral acceleration is the first value, the control to generate the set yaw moment in the vehicle is executed, while when the lateral acceleration is the second value smaller than the first value, the set yaw is executed. It is characterized in that it is configured to prohibit the execution of control that causes a moment in the vehicle.
According to the present invention configured in this way, when the lateral acceleration is relatively small, the control that causes the yaw moment in the vehicle is prohibited, so that the driver is appropriately suppressed from giving a sense of discomfort due to the execution of the control. can do.

According to the present invention, in a vehicle control device that controls a braking device to apply a yaw moment to a vehicle, a strong sense of control intervention can be achieved by performing control that applies the yaw moment in consideration of the magnitude of lateral acceleration. It is possible to appropriately suppress giving a feeling of strangeness to the driver.

It is a block diagram which shows the whole structure of the vehicle which mounted the control device of the vehicle according to the Embodiment of this invention. It is a block diagram which shows the electric structure of the control device of the vehicle by embodiment of this invention. It is a flowchart of attitude control processing by embodiment of this invention. It is a flowchart of the addition deceleration setting process by embodiment of this invention. It is a map which showed the relationship between the additional deceleration and the steering speed by embodiment of this invention. It is a flowchart of the target yaw moment setting process by embodiment of this invention. It is a map which defines the threshold value used for setting the target yaw moment in the embodiment of this invention. It is a time chart which showed the time change of the parameter about the vehicle attitude control when the vehicle equipped with the vehicle control device according to the embodiment of the present invention makes a turn. It is a flowchart of the target yaw moment setting process by the modification of embodiment of this invention. It is a map which defines the threshold value used for setting the target yaw moment in the modification of the embodiment of this invention.

Hereinafter, a vehicle control device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

<System configuration>
First, the system configuration of the vehicle equipped with the vehicle control device according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an overall configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 indicates a vehicle equipped with a vehicle control device according to the present embodiment. An engine 4 is mounted on the front portion of the vehicle body of the vehicle 1 as a drive source for driving the drive wheels (the left and right front wheels 2 in the example of FIG. 1). The engine 4 is an internal combustion engine such as a gasoline engine or a diesel engine, and in the present embodiment, it is a gasoline engine having a spark plug.

Further, the vehicle 1 has a steering angle that detects the rotation angle of a steering device (steering wheel 6 or the like) for steering the vehicle 1 and a steering column (not shown) connected to the steering wheel 6 in this steering device. It includes a sensor 8, a vehicle speed sensor 10 that detects vehicle speed, a yaw rate sensor 12 that detects yaw rate, and a lateral acceleration sensor 13 that detects lateral acceleration. Each of these sensors outputs the detected value to the PCM (Power-train Control Module) 14.

Further, the vehicle 1 is provided with a brake control system 18 that supplies brake fluid pressure to the wheel cylinders and brake calipers of the brake device 16 provided on each wheel. The brake control system 18 includes a hydraulic pump 20 that generates the brake hydraulic pressure required to generate a braking force in the brake device 16 provided on each wheel. The hydraulic pump 20 is driven by, for example, the electric power supplied from the battery, and generates the brake hydraulic pressure required to generate the braking force in each brake device 16 even when the brake pedal is not depressed. It is possible. Further, the brake control system 18 is a valve unit 22 for controlling the hydraulic pressure supplied from the hydraulic pump 20 to the brake device 16 of each wheel, which is provided in the hydraulic pressure supply line to the brake device 16 of each wheel. (Specifically, it is equipped with a solenoid valve). For example, the opening degree of the valve unit 22 is changed by adjusting the amount of electric power supplied from the battery to the valve unit 22. Further, the brake control system 18 includes a hydraulic pressure sensor 24 that detects the hydraulic pressure supplied from the hydraulic pressure pump 20 to the brake device 16 of each wheel. The hydraulic pressure sensor 24 is arranged, for example, at a connection portion between each valve unit 22 and a hydraulic pressure supply line on the downstream side thereof, detects the hydraulic pressure on the downstream side of each valve unit 22, and determines the detected value by PCM (Power-train). Output to Control Module) 14.

The brake control system 18 calculates the hydraulic pressure independently supplied to the wheel cylinders and brake calipers of each wheel based on the braking force command value input from the PCM 14 and the detection value of the hydraulic pressure sensor 24, and calculates the hydraulic pressures thereof. The rotation speed of the hydraulic pump 20 and the opening degree of the valve unit 22 are controlled according to the hydraulic pressure.

Next, with reference to FIG. 2, the electrical configuration of the vehicle control device according to the embodiment of the present invention will be described. FIG. 2 is a block diagram showing an electrical configuration of a vehicle control device according to an embodiment of the present invention.

The PCM14 (vehicle control device) according to the present embodiment generates the engine 4 based on the detection signals of the sensors 8 to 13 and 24 described above and the detection signals output by various sensors for detecting the operating state of the engine 4. A control signal is sent to control each part of the engine 4 that functions as a torque control mechanism (for example, a throttle valve, a turbo supercharger, a variable valve mechanism, an ignition device, a fuel injection valve, an EGR device, etc.) and a brake control system 18. Output.

The PCM 14 and the brake control system 18 each include one or more processors and various programs (basic control programs such as an OS) that are interpreted and executed on the processors, and application programs that are started on the OS and realize specific functions. ), And a computer equipped with an internal memory such as a ROM or RAM for storing programs and various data. Although details will be described later, the PCM 14 and the brake control system 18 correspond to the vehicle control device in the present invention.

<Vehicle attitude control>
Next, the specific control contents executed by the vehicle control device will be described. First, with reference to FIG. 3, the overall flow of the attitude control process performed by the vehicle control device in the embodiment of the present invention will be described. FIG. 3 is a flowchart of the attitude control process according to the embodiment of the present invention.

The attitude control process of FIG. 3 is activated when the ignition of the vehicle 1 is turned on and the power is turned on to the control device of the vehicle, and is repeatedly executed at a predetermined cycle (for example, 50 ms).
When the attitude control process is started, as shown in FIG. 3, in step S1, the PCM 14 acquires various sensor information regarding the driving state of the vehicle 1. Specifically, the PCM 14 detects the steering angle detected by the steering angle sensor 8, the vehicle speed detected by the vehicle speed sensor 10, the yaw rate detected by the yaw rate sensor 12, the lateral acceleration detected by the lateral acceleration sensor 13, and the hydraulic pressure sensor 24. The detection signals output by the various sensors described above, including the hydraulic pressure and the gear stage currently set in the transmission of the vehicle 1, are acquired as information on the operating state.

Next, in step S2, the PCM 14 sets the target acceleration based on the operating state of the vehicle 1 including the operation of the accelerator pedal acquired in step S1. Specifically, the PCM14 has an acceleration corresponding to the current vehicle speed and gear stage from an acceleration characteristic map (created in advance and stored in a memory or the like) defined for various vehicle speeds and various gear stages. Select a characteristic map and refer to the selected acceleration characteristic map to determine the target acceleration corresponding to the current accelerator opening.

Next, in step S3, the PCM 14 determines the basic target torque of the engine 4 for achieving the target acceleration determined in step S2. In this case, the PCM 14 determines the basic target torque within the range of torque that can be output by the engine 4 based on the current vehicle speed, gear stage, road surface gradient, road surface μ, and the like.

Further, in parallel with the processes of steps S2 and S3, in step S4, the PCM 14 executes the additional deceleration setting process, and generates deceleration in the vehicle 1 based on the value related to the steering angle (steering angle related value). The torque reduction amount required to control the vehicle attitude is determined. In the present embodiment, a case where the steering angle is used as the steering angle-related value will be described. The details of the additional deceleration setting process will be described later.

Next, in step S5, the PCM 14 executes the target yaw moment setting process and sets the target yaw moment to be given to the vehicle 1 in order to control the vehicle posture based on the turning state of the vehicle 1. In the present embodiment, the case where the steering speed is used as the turning state will be described. The details of the target yaw moment setting process will be described later.

After the processing of steps S3 and S5, the process proceeds to step S9, and the PCM 14 determines the final target torque based on the basic target torque determined in step S3 and the torque reduction amount determined in step S4. Specifically, the PCM 14 uses a value obtained by subtracting the torque reduction amount from the basic target torque as the final target torque. If the torque reduction amount is not determined in step S4 (that is, when the torque reduction amount is 0), the PCM 14 applies the basic target torque as it is as the final target torque.

After step S9, the process proceeds to step S10, and the PCM 14 controls the engine 4 so as to output the final target torque set in step S9. Specifically, the PCM 14 has various state quantities (for example, air filling amount, fuel injection amount, etc.) required to realize the final target torque based on the final target torque set in step S9 and the engine speed. Intake air temperature, oxygen concentration, etc.) are determined, and each actuator that drives each component of the engine 4 is controlled based on the state quantities thereof. In this case, the PCM 14 sets a limit value or a limit range according to the state amount, sets a control amount of each actuator such that the state value complies with the limit value or the limit by the limit range, and executes control.
More specifically, when the engine 4 is a gasoline engine, the PCM 14 determines the ignition timing of the spark plug 24 and the basic target torque when the final target torque is determined by subtracting the torque reduction amount from the basic target torque. The generated torque of the engine 4 is reduced by retarding (retarding) the ignition timing when the final target torque is used as it is.
Further, when the engine 4 is a diesel engine, when the final target torque is determined by subtracting the torque reduction amount from the basic target torque, the PCM14 uses the fuel injection amount as the basic target torque as it is as the final target torque. The generated torque of the engine 4 is reduced by reducing the fuel injection amount at that time.

Next, in step S11, the brake control system 18 controls the brake device 16 so as to apply the target yaw moment set in step S5 to the vehicle 1. The brake control system 18 stores in advance a map that defines the relationship between the yaw moment command value and the rotation speed of the hydraulic pump 20, and by referring to this map, it is set in the target yaw moment setting process in step S5. The hydraulic pump 20 is operated at the rotation speed corresponding to the yaw moment command value (for example, by increasing the power supply to the hydraulic pump 20, the hydraulic pump 20 reaches the rotation speed corresponding to the braking force command value. (Increase the number of revolutions).

Further, the brake control system 18 stores in advance a map that defines the relationship between the yaw moment command value and the opening degree of the valve unit 22, for example, and corresponds to the yaw moment command value by referring to this map. The valve unit 22 is individually controlled so as to have an opening degree (for example, by increasing the power supplied to the solenoid valve, the opening degree of the solenoid valve is increased to the opening degree corresponding to the braking force command value). Adjust the braking force of the wheels. If the target yaw moment is not set in step S5, the brake control system 18 does not control step S11.
After step S11, the PCM 14 ends the attitude control process.

Next, the additional deceleration setting process according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 is a flowchart of the additional deceleration setting process according to the embodiment of the present invention, and FIG. 5 is a map showing the relationship between the additional deceleration and the steering speed according to the embodiment of the present invention.

When the additional deceleration setting process is started, in step S21, the PCM 14 determines whether or not the turning operation of the steering wheel 6 is in progress (that is, the steering angle (absolute value) is increasing).
As a result, when the cutting operation is in progress, the process proceeds to step S22, and the PCM 14 calculates the steering speed based on the steering angle acquired from the steering angle sensor 8 in step S1 of the attitude control process of FIG.

Next, in step S23, the PCM 14 determines whether or not _{the steering speed is equal to or higher than a predetermined threshold value S 1.} As a result, when the steering speed is equal to _{or higher than the threshold value S 1} , the process proceeds to step S24, and the PCM 14 sets the additional deceleration based on the steering speed. This additional deceleration is a deceleration that should be added to the vehicle in response to the steering operation in order to control the vehicle attitude according to the driver's intention.

Specifically, the PCM 14 sets the additional deceleration corresponding to the steering speed calculated in step S22 based on the relationship between the additional deceleration shown in the map of FIG. 5 and the steering speed. The horizontal axis in FIG. 5 indicates the steering speed, and the vertical axis indicates the additional deceleration. As shown in FIG. 5, when the steering speed is _{less than the threshold value S 1} , the corresponding additional deceleration is 0. That is, when the steering speed is _{less than the threshold value S 1} , the PCM 14 does not perform control for adding deceleration to the vehicle 1 based on the steering operation (specifically, reduction of the generated torque of the engine 4).

On the other hand, when the steering speed _{is equal to or higher than the threshold value S 1} , the additional deceleration corresponding to the steering speed gradually approaches a _{predetermined upper limit value D max as the steering speed increases.} That is, as the steering speed increases, the additional deceleration increases, and the rate of increase in the amount of increase decreases. This upper limit value D _max is set to such a deceleration that the driver does not feel that there is control intervention even if the deceleration is added to the vehicle 1 according to the steering operation (for example, 0.5 m / s ² ≈ 0). .05G). Further, when the steering speed is equal to or higher than the _{threshold value S 2} which is larger than the _{threshold value S 1} , the additional deceleration is maintained at the _{upper limit value D max.}

Next, in step S25, the PCM 14 determines the torque reduction amount based on the additional deceleration set in step S24. Specifically, the PCM 14 determines the amount of torque reduction required to realize the additional deceleration due to the decrease in the generated torque of the engine 4 based on the current vehicle speed, gear stage, road surface gradient, etc. acquired in step S1. decide. After step S25, the PCM 14 ends the additional deceleration setting process and returns to the main routine.

Further, in step S21, if not in turning operation of the steering wheel 6, or, in step S23, if the steering speed is less than the threshold value S _1, PCM 14, the additional deceleration setting without configuring additional deceleration Finish the process and return to the main routine. In this case, the torque reduction amount becomes 0.

Next, the target yaw moment setting process according to the embodiment of the present invention will be described with reference to FIGS. 6 and 7.

FIG. 6 is a flowchart of the target yaw moment setting process according to the embodiment of the present invention, and FIG. 7 is a map showing a threshold value used in the target yaw moment setting process according to the embodiment of the present invention.

As shown in FIG. 6, when the target yaw moment setting process is started, in step S31, the PCM 14 sets the target yaw rate and the target lateral jerk based on the steering angle and vehicle speed acquired in step S1 of the attitude control process of FIG. calculate. Specifically, the PCM 14 calculates the target yaw rate by multiplying the steering angle by a coefficient corresponding to the vehicle speed. Further, the PCM 14 calculates the target lateral jerk based on the steering speed and the vehicle speed.

Next, in step S32, the PCM 14 calculates the difference (yaw rate difference) Δγ between the yaw rate (actual yaw rate) detected by the yaw rate sensor 12 acquired in step S1 of the attitude control process of FIG. 3 and the target yaw rate calculated in step S31. calculate.

_{Next, in step S33, the PCM 14 sets the threshold values Y 1} and S ₃ used in the determination in the following processing according to the lateral acceleration detected by the lateral acceleration sensor 13. The threshold Y ₁ and S ₃ are in principle if a predetermined parameter according to the turning state of the vehicle 1 is the threshold value Y ₁ and S ₃ above, to set the target yaw moment to be applied to the vehicle (The target yaw moment is not set if the predetermined parameters are _{less than the thresholds Y 1} and S _3). The setting of the _{threshold values Y 1} and S ₃ will be specifically described with reference to FIG. 7. In the description of FIG. 7, for convenience of explanation, "threshold value Y ₁ " and "threshold value S ₃ " may be simply referred to as "threshold value".

FIG. 7 is a map defining a threshold value used to set a target yaw moment in an embodiment of the present invention. This map is created in advance and stored in a memory or the like. In FIG. 7, the horizontal axis shows the lateral acceleration, and the vertical axis shows the threshold value. As shown in FIG. 7, as the lateral acceleration becomes smaller, the threshold value becomes larger, specifically, the values of both the _{threshold value Y 1} and the threshold value S _{3 become larger.}

By applying such a threshold value, when the lateral acceleration becomes small, it becomes difficult to satisfy the condition that the predetermined parameter according to the turning state of the vehicle 1 is equal to or more than the threshold value. As a result, the possibility that the target yaw moment is set in the following processing is reduced. That is, when the lateral acceleration becomes small, it becomes difficult to execute the control of applying the target yaw moment in the direction opposite to the actual yaw rate to the vehicle 1 by the brake device 16. By doing so, when the lateral acceleration generated in the vehicle 1 is small, it is possible to appropriately suppress giving the driver a sense of discomfort due to the control of applying the yaw moment to the vehicle 1, specifically, a strong sense of control intervention. ..

Note that FIG. 7 _{schematically shows the trends of both the threshold values Y 1} and S ₃ according to the lateral acceleration, and in reality, the threshold values Y ₁ and the threshold values Y 1 and S 3 according to the lateral acceleration are actually shown according to such a tendency. Each of S ₃ is set separately (the same applies to FIG. 10 shown later). That is, _{for each of the threshold values Y 1} and S ₃ , a map corresponding to the lateral acceleration is defined, and in principle, the threshold _{values Y 1} and the threshold value S ₃ are set to different values.

Further, although the lateral acceleration generated in the vehicle 1 changes from moment to moment, the threshold value applied may be changed according to such a changing lateral acceleration, or the threshold value applied may be changed according to the lateral acceleration. You may not let it. In the latter case, the threshold value may not be changed after the predetermined parameter becomes equal to or higher than the threshold value and the control for applying the target yaw moment to the vehicle 1 is started. That is, during the execution of the control for applying the target yaw moment to the vehicle 1, the threshold value according to the lateral acceleration at the start of the control is consistently used during the control without changing the threshold value according to the change in the lateral acceleration. Just do it.

Returning to FIG. 6, the description of the processes after step S34 will be resumed. In step S34, the PCM14 is in the turning back operation of the steering wheel 6 (that is, the steering angle is decreasing), and the change speed Δγ ′ of the yaw rate difference obtained by time-differentiating the yaw rate difference Δγ is the threshold value Y _1. It is determined whether or not it is the above. The PCM 14 uses the value set in step S33 as the _{threshold value Y 1.}

As a result, when the switchback operation is performed and the yaw rate difference change rate Δγ ′ _{is equal to or greater than the threshold value Y 1} , the process proceeds to step S35, and the PCM 14 is opposite to the actual yaw rate of the vehicle 1 based on the yaw rate difference change rate Δγ ′. Set the surrounding yaw moment as the target yaw moment. Specifically, the PCM 14 calculates the magnitude of the target yaw moment by multiplying a predetermined coefficient by the change rate Δγ ′ of the yaw rate difference.

On the other hand, in step S34, when the steering wheel 6 is not being turned back (that is, the steering angle is constant or increasing), the process proceeds to step S36, and the PCM14 targets the actual yaw rate at the change speed Δγ ′ of the yaw rate difference. It is determined whether or not the direction is larger than the yaw rate (that is, the direction in which the behavior of the vehicle 1 becomes oversteer) and the change speed Δγ ′ of the yaw rate difference is equal to _{or more than the threshold value Y 1.} Specifically, the PCM14 is used when the yaw rate difference is decreasing when the target yaw rate is equal to or higher than the actual yaw rate, or when the yaw rate difference is increasing when the target yaw rate is less than the actual yaw rate. The rate of change Δγ ′ of the yaw rate difference is determined to be the direction in which the actual yaw rate becomes larger than the target yaw rate.

As a result, when the change rate Δγ ′ of the yaw rate difference is in the direction in which the actual yaw rate is larger than the target yaw rate and the change rate Δγ ′ of the yaw rate difference is the threshold value Y ₁ or more, the process proceeds to step S35, and the PCM 14 is set to the yaw rate difference. Based on the change speed Δγ', the yaw moment in the opposite direction to the actual yaw rate of the vehicle 1 is set as the target yaw moment.

After step S35, or in step S36, if the change rate Δγ ′ of the yaw rate difference is in the direction in which the actual yaw rate is larger than the target yaw rate or the change rate Δγ ′ of the yaw rate difference _{is less than the threshold value Y 1} , the process proceeds to step S37. , PCM 14 is cut back during operation of the steering wheel 6 (i.e. in the steering angle is decreased), and the steering speed is determined whether a predetermined threshold S ₃ or more. The PCM 14 uses the value set in step S33 as the _{threshold value S 3.}

As a result, if and steering speed in the switch-back is the threshold value S ₃ or more, the process proceeds to step S38, PCM 14, based on the target lateral jerk calculated in step S31, the actual yaw rate of the vehicle 1 the yaw moment opposite direction Set as the second target yaw moment. Specifically, the PCM 14 calculates the magnitude of the second target yaw moment by multiplying the target lateral jerk by a predetermined coefficient.

After step S38, the or when cut is not being returning operation (i.e. the steering angle is in constant or increased) or steering speed of the steering wheel 6 is less than the threshold value S ₃ in step S37, the process proceeds to step S39, PCM 14 Sets the larger of the target yaw moment set in step S35 and the second target yaw moment set in step S38 as the yaw moment command value. If the target yaw moment is not set in both steps S35 and S38 (that is, if the processes of steps S35 and S38 are not executed), the PCM 14 does not set the yaw moment command value in step S39. .. After step S39, the PCM 14 ends the target yaw moment setting process and returns to the main routine.

Next, the operation of the vehicle control device according to the embodiment of the present invention will be described with reference to FIG. FIG. 8 is a time chart showing time changes of various parameters related to attitude control when the vehicle 1 equipped with the vehicle control device according to the embodiment of the present invention is turned and traveled.

In FIG. 8, chart (a) shows the steering angle, chart (b) shows the steering speed, chart (c) shows the target lateral jerk used to set the target yaw moment, and chart (d) shows the target lateral jerk. The target yaw moment (corresponding to the yaw moment command value input from the PCM 14 to the brake control system 18) is shown. In the chart (b), reference numeral S31 is a threshold S ₃ lateral acceleration is applied to the determination of the steering speed when relatively large (hereinafter referred to as "threshold S31".) Indicates, reference numeral step S32, horizontal acceleration is relatively small threshold S ₃ is applied to the determination of the steering speed when (hereinafter to. denoted as "threshold S32" hereinafter). According to the map of FIG. 7, the higher the threshold S ₃ lateral acceleration is small becomes large, the threshold value S32 in the time lateral acceleration is relatively small, is larger than the threshold value S31 in the time lateral acceleration is relatively large (absolute value Compare with).

As shown in FIG. 8, the steering operation is switched from the turning operation to the turning back operation (see chart (a)), and the absolute value of the steering speed increases at this switching timing (see chart (b)). When the lateral acceleration is relatively large, the steering speed (absolute value) becomes the threshold value S31 or more at time t1. In particular, at time t1, a steering operation switching back operation, and the steering speed (absolute value) the condition that is the threshold value S31 (S ₃₎ or more (see step S37 in FIG. 6) is established. As a result, when the lateral acceleration is relatively large, the target yaw moment to be applied to the vehicle 1 is set from the time t1 (see the solid line in the chart (d)), and the control to apply the yaw moment to the vehicle 1 is executed. NS. Then, at time t2, when the turning back operation of the steering wheel 6 is completed (see chart (a)), the target yaw moment is set to 0, and the control for applying the yaw moment to the vehicle 1 is terminated.

On the other hand, when the lateral acceleration is relatively small, the steering speed (absolute value) exceeds the threshold value S32 from the start to the end of the turning back operation of the steering wheel 6 (between time t1 and time t2). Nothing (see chart (b)). Thus, a steering operation switching back operation, and, provided that the steering speed (absolute value) is the threshold value S32 (S ₃₎ or more (see step S37 in FIG. 6) is not satisfied. Therefore, when the lateral acceleration is relatively small, the target yaw moment to be applied to the vehicle 1 is maintained at 0 (see the broken line in the chart (d)), and the control for applying the yaw moment to the vehicle 1 is not executed. Therefore, according to the present embodiment, when the lateral acceleration is small, it is possible to appropriately suppress the execution of the control for applying the yaw moment to the vehicle 1.

<Effect>
Next, the operation and effect of the vehicle control device according to the embodiment of the present invention will be described.

According to the present embodiment, the PCM 14 controls the vehicle 1 to generate a yaw moment in the opposite direction to the yaw rate generated in the vehicle 1 when the value corresponding to the turning state of the vehicle becomes equal to or higher than the threshold value. Execute, and make this threshold larger when the lateral acceleration is small than when it is not. As a result, when the lateral acceleration is small, by increasing the threshold value, it is possible to make it difficult to execute the control that causes the yaw moment in the vehicle 1, that is, it is possible to suppress the execution of the control. As a result, when the lateral acceleration is small, it is possible to appropriately suppress giving the driver a sense of discomfort due to the control that causes the yaw moment in the vehicle 1, specifically, a strong sense of control intervention. On the other hand, when the lateral acceleration is large, it is possible to execute a control for generating a yaw moment in the vehicle 1 and appropriately secure the effect of this control.

Further, according to the present embodiment, since the PCM 14 executes the control to generate the yaw moment in the vehicle 1 when the steering angle is decreasing, the control is appropriately executed at the time of the turning back operation of the steering wheel 6. can do. Therefore, the vehicle 1 in the turning state can be quickly turned in the straight-ahead direction.

Further, according to the present embodiment, the PCM 14 sets a target lateral jerk based on the steering speed and the vehicle speed when the steering speed acquired based on the detection value of the steering angle sensor 8 becomes the threshold value S _{3 or more.} Set the yaw moment based on the target lateral jerk. As a result, a yaw moment of a magnitude corresponding to the speed of the driver's steering operation can be applied in the direction of suppressing the turning of the vehicle 1, and the vehicle behavior can be quickly stabilized according to the driver's steering operation. ..

Further, according to the present embodiment, in the PCM 14, the change speed of the difference between the actual yaw rate actually generated in the vehicle 1 and the target yaw rate set based on the detection value of the steering angle sensor 8 is the threshold value Y ₁ or more. At that time, the yaw moment is set based on the rate of change. As a result, when the steering wheel is operated on a low μ road such as a snow-packed road, the yaw moment in the direction of immediately suppressing the turning in response to a sudden change in the yaw rate difference due to the response delay of the actual yaw rate is applied to the vehicle. It can be given to 1, and in the situation before the behavior of the vehicle 1 becomes unstable, the vehicle behavior can be quickly stabilized according to the steering operation of the driver.

<Modification example>
Next, a modified example of this embodiment will be described.

(Modification example 1)
In the above-described embodiment, a threshold value for determining whether or not the control for applying the yaw moment to the vehicle 1 needs to be executed is set according to the lateral acceleration. Specifically, the threshold value is not set when the lateral acceleration is small. By making it larger than the time, the execution of the control for applying the yaw moment to the vehicle 1 when the lateral acceleration is small is suppressed. In the modified example, by performing the determination using the threshold value according to the lateral acceleration in this way, the determination based on the magnitude of the lateral acceleration itself is performed instead of suppressing the execution of the control for applying the yaw moment to the vehicle 1. Therefore, the execution of the control for applying the yaw moment to the vehicle 1 may be suppressed. Specifically, in the modified example, when the lateral acceleration is less than a predetermined value, the control of uniformly applying the yaw moment to the vehicle 1 may be prohibited.

FIG. 9 is a flowchart of a target yaw moment setting process according to a modified example of the embodiment of the present invention. The target yaw moment setting process of FIG. 9 is executed instead of the target yaw moment setting process shown in FIG. In the following, only the configuration different from the target yaw moment setting process of FIG. 6 will be described, and the description of the same configuration as the target yaw moment setting process of FIG. 6 will be omitted.

The target yaw moment setting process of FIG. 9 is different from the target yaw moment setting process of FIG. 6 in that it does not include step S33 but includes step S30. It is the same as the target yaw moment setting process of 6. That is, in the modified example, the PCM 14 does not set the threshold value according to the lateral acceleration using the map of FIG. 7, and instead determines the step S30. In the modified example, the PCM 14 uses constant thresholds Y ₁ and S ₃ that do not depend on the lateral acceleration.

In step S30, the PCM 14 determines whether or not the lateral acceleration detected by the lateral acceleration sensor 13 is equal to or greater than a predetermined value. As a result, when the lateral acceleration is equal to or higher than the predetermined value (step S30: Yes), the process proceeds to step S31, while when the lateral acceleration is less than the predetermined value (step S30: No), the target yaw moment is set. The process ends. That is, the PCM 14 does not set the target yaw moment when the lateral acceleration is less than a predetermined value. By doing so, the PCM 14 prohibits the execution of the control for applying the yaw moment to the vehicle 1 when the lateral acceleration is less than a predetermined value. As a predetermined value for determining the lateral acceleration in step S30, when the lateral acceleration is less than this value, the lateral acceleration is applied so that the discomfort due to the control of applying the yaw moment to the vehicle 1 becomes remarkable. Just do it.

According to the modification described above, when the lateral acceleration is small, the execution of the control for applying the yaw moment to the vehicle 1 is prohibited, so that the driver is appropriately suppressed from giving a sense of discomfort due to the execution of the control. Can be done.

(Modification 2)
In the above-described embodiment, the threshold value is reduced as the yaw rate increases in the entire region of the yaw rate (see FIG. 7), but the threshold value is not limited to be defined in this way. FIG. 10 is a map defining a threshold value used for setting a target yaw moment in a modified example of the embodiment of the present invention. In one modification, as shown in FIG. 10A, when the lateral acceleration is less than the predetermined value, the threshold value is increased as the lateral acceleration becomes smaller, and when the lateral acceleration is equal to or more than the predetermined value. May set the threshold value to a constant value regardless of the lateral acceleration. As this predetermined value, in the region where the lateral acceleration is less than this value, the lateral acceleration may be applied so that the discomfort due to the control of applying the yaw moment to the vehicle 1 can become remarkable.

In another modification, as shown in FIG. 10B, when the lateral acceleration is less than the predetermined value, the threshold value may be larger than when the lateral acceleration is equal to or more than the predetermined value. In this example, the threshold value is constant regardless of the lateral acceleration in both the case where the lateral acceleration is less than the predetermined value and the case where the lateral acceleration is equal to or more than the predetermined value, but when the yaw rate is less than the predetermined value, The threshold value is larger than when it is equal to or more than a predetermined value. In addition, the same value as in FIG. 10A may be applied to the predetermined value in FIG. 10B.

Even if the threshold values shown in FIGS. 10A and 10B as described above are applied, the execution of the control for applying the yaw moment to the vehicle 1 is suppressed when the lateral acceleration is small, and the execution of the control is performed. It is possible to appropriately suppress giving a feeling of strangeness to the driver.

(Modification example 3)
In the above-described embodiment, the lateral acceleration detected by the lateral acceleration sensor 13 is used, but instead, the lateral acceleration calculated based on the vehicle speed detected by the vehicle speed sensor 10 and the yaw rate detected by the yaw rate sensor 12 is used. May be good.

(Modification example 4)
In the above-described embodiment, the steering speed and the change speed of the difference between the actual yaw rate and the target yaw rate (yaw rate difference) are used as the turning state of the vehicle 1, but in addition to these, yaw acceleration, lateral jerk, etc. are used. You may use it.

(Modification 5)
In the above embodiment, it has been described that the rotation angle of the steering column connected to the steering wheel 6 is used as the steering angle, but various states in the steering system are used instead of the rotation angle of the steering column or together with the rotation angle of the steering column. The amount (rotational angle of the motor that applies the assist torque, rack displacement in the rack and pinion, etc.) may be used as the steering angle.

1 Vehicle 2 Front wheels 4 Engine 6 Steering wheel 8 Steering angle sensor 10 Vehicle speed sensor 12 Yaw rate sensor 13 Lateral acceleration sensor 14 PCM
16 Brake device 18 Brake control system

Claims (5)

A vehicle control device including a steering device, a braking device capable of applying different braking forces to the left and right wheels, and a processor.
The processor
When the value corresponding to the turning state of the vehicle becomes equal to or higher than the threshold value, a yaw moment opposite to the yaw rate generated in the vehicle is set, and the set yaw moment is generated in the vehicle. Control the braking device,
A vehicle control device, characterized in that when the lateral acceleration generated in the vehicle is small, the threshold value is made larger than when it is not. The processor controls the braking device so that the set yaw moment is generated in the vehicle when the value corresponding to the turning state is equal to or higher than the threshold value and the steering angle of the steering device is decreasing. The vehicle control device according to claim 1, wherein the vehicle control device is configured to do so. The processor
As the value corresponding to the turning state, the steering speed acquired based on the detection value of the steering angle sensor that detects the steering angle of the steering device is used.
1. 2. The vehicle control device according to 2. The processor
As a value according to the turning state, the change speed of the difference between the actual yaw rate actually generated in the vehicle and the target yaw rate set based on the detection value of the steering angle sensor that detects the steering angle of the steering device is used. Use,
The vehicle control device according to claim 1 or 2, wherein the yaw moment is set based on the change speed when the change speed becomes equal to or higher than the threshold value. A vehicle control device including a steering device, a braking device capable of applying different braking forces to the left and right wheels, and a processor.
The processor
Based on the turning state of the vehicle, a yaw moment opposite to the yaw rate generated in the vehicle is set, and the brake device is controlled so as to generate the set yaw moment in the vehicle.
When the lateral acceleration generated in the vehicle is the first value, the control for generating the set yaw moment in the vehicle is executed, while the lateral acceleration is smaller than the first value in the second value. When the above is the case, the vehicle control device is configured to prohibit the execution of the control that causes the set yaw moment to be generated in the vehicle.

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