JP2019167038A - Vehicle control device - Google Patents

Abstract

To provide a vehicle control device for performing vehicle yaw control for adding a yaw moment to a vehicle, in which taking a slope of a road surface on which a vehicle travels into consideration, vehicle yaw controls is so executed as to be suitable for the slope.SOLUTION: A vehicle control device comprises: a steering gear including a steering wheel 6 and so on; a brake control system 16 which can give different brake forces to left and right wheels; and a PCM 14 including a processor and so on. The PCM 14 executes vehicle yaw control for controlling the brake control system 16 so as to add a yaw moment in a direction opposite to a yaw rate generated in a vehicle 1 to the vehicle 1, on the basis of an operation for switching back the steering wheel 6. When the vehicle 1 travels on a downhill road at the time of switching back operation for the steering wheel 6, vehicle yaw control is suppressed compared to the case other than the afore-said case.SELECTED DRAWING: Figure 6

Description

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

  2. Description of the Related Art Conventionally, there are known devices that control the behavior of a vehicle in a safe direction when the behavior of the vehicle becomes unstable due to slip or the like (such as a skid prevention device). Specifically, it is known to detect that understeer or oversteer behavior has occurred in the vehicle during cornering of the vehicle, and to impart appropriate deceleration to the wheels to suppress them. ing.

  In addition, unlike the control for improving the safety in the driving state where the behavior of the vehicle becomes unstable as described above, the acceleration / deceleration automatically linked with the steering operation operated from the daily driving range is automatically performed. 2. Description of the Related Art A vehicle motion control device that reduces skid in a driving region is known (see, for example, Patent Document 1). In particular, this Patent Document 1 discloses a vehicle motion control device including a first mode for controlling acceleration / deceleration in the longitudinal direction of the vehicle and a second mode for controlling the yaw moment of the vehicle. Yes.

Japanese Patent No. 5143103

  As described above, in the technique disclosed in Patent Document 1, the yaw moment is applied to the vehicle in the second mode. The control for applying the yaw moment to the vehicle is typically executed when a steering wheel (hereinafter simply referred to as “steering”) is switched back. That is, when the steering is turned back, a yaw moment reverse to the yaw rate generated in the vehicle is added to suppress the turning of the vehicle, in other words, to promote the return of the vehicle in the straight direction. As described above, a braking force is applied to the turning outer wheel by the brake device. Hereinafter, the control for adding such a yaw moment to the vehicle is appropriately referred to as “vehicle yaw control”.

  By the way, when the vehicle is traveling on a downhill road, the load applied to the front wheels (turning wheels) is larger than when the vehicle is traveling on a flat road or an uphill road. Therefore, the vehicle in a turning state tends to be promoted to return straight. This is because the load applied to the front wheel when traveling on a downhill road is relatively large, and therefore the front wheel has a large restoring force of the tire according to the longitudinal force (acceleration force) of the tire. Therefore, when a yaw moment similar to that when traveling on a flat road or the like is applied by vehicle yaw control when traveling on a downhill road, an excessive state of control intervention may occur, and the driver may feel uncomfortable.

  On the other hand, when the vehicle is traveling on an uphill road, the load applied to the front wheels (turning wheels) is smaller than when the vehicle is traveling on a flat road or downhill road. Vehicle responsiveness tends to deteriorate. This is because the load applied to the front wheel when traveling on an uphill road is relatively small, and therefore the restoring force of the tire according to the longitudinal force of the tire is small at the front wheel. Therefore, even if a yaw moment similar to that on flat roads is applied during uphill travel by vehicle yaw control, vehicle responsiveness improvement function by vehicle yaw control, that is, rapid vehicle behavior stabilization according to steering operation There is a tendency that functions cannot be obtained sufficiently.

  The present invention has been made to solve the above-described problems of the prior art, and in a vehicle control apparatus that performs vehicle yaw control that adds a yaw moment to a vehicle, considers the gradient of the road surface on which the vehicle travels. The purpose is to perform vehicle yaw control suitable for this.

In order to achieve the above object, the present invention provides a vehicle control device including a steering device, a brake device capable of applying different braking forces to left and right wheels, and a controller. Based on the return operation of the steering device, vehicle yaw control is performed to control the brake device so that a yaw moment that is reverse to the yaw rate generated in the vehicle is applied to the vehicle. When traveling on a slope, the vehicle yaw control is suppressed more than when it is not.
According to the present invention configured as described above, since the vehicle yaw control is suppressed when the vehicle is traveling on the downhill road during the return operation of the steering device, the control intervention is performed by executing the vehicle yaw control at this time. Can be appropriately suppressed from becoming excessive. That is, when traveling downhill, because the load applied to the front wheels (turning wheels) is relatively large and the restoring moment of the front wheels is large, the return of the vehicle in a turning state tends to be accelerated. In the present invention, by suppressing the vehicle yaw control when traveling on a downhill road, it is possible to appropriately suppress the vehicle from returning excessively in the straight direction due to the addition of the yaw moment by the control.

In the present invention, preferably, the controller executes the vehicle yaw control when a value corresponding to the return operation of the steering device is equal to or greater than a predetermined threshold, and when the road slope of the downhill road is large, than when it is not. Is also configured to increase the threshold.
According to the present invention configured as described above, when the road slope (downhill slope) of the downhill road is large, the threshold value for determining whether to execute the vehicle yaw control is increased, so the road surface of the downhill road Vehicle yaw control can be effectively suppressed when the gradient is relatively large.

In the present invention, preferably, the controller is configured to reduce the yaw moment to be applied by the vehicle yaw control when the road slope of the downhill road is large than when it is not.
According to the present invention configured as described above, when the road gradient (downhill gradient) of the downhill road is large, the yaw moment applied by the vehicle yaw control is reduced, so that the road gradient of the downhill road is relatively large. Vehicle yaw control can be effectively suppressed.

In another aspect, 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 left and right wheels, and a controller. The controller executes vehicle yaw control for controlling the brake device so as to add a yaw moment reverse to the yaw rate generated in the vehicle to the vehicle based on the return operation of the steering device. When the vehicle is traveling on an uphill road during operation, the vehicle yaw control is promoted more than when it is not.
According to the present invention configured as described above, since the vehicle yaw control is promoted when the vehicle is traveling on the uphill road during the return operation of the steering device, the vehicle responsiveness improving function by the vehicle yaw control at this time That is, it is possible to appropriately ensure a quick vehicle behavior stabilization function according to the steering operation. That is, when traveling on an uphill road, the load applied to the front wheels (turning wheels) is relatively small and the restoring moment of the front wheels is small. Since there is a tendency that the effect of the control cannot be obtained sufficiently, in the present invention, the vehicle yaw control can be appropriately ensured by the vehicle yaw control by promoting the vehicle yaw control when traveling on the uphill road. .

In the present invention, preferably, the controller executes the vehicle yaw control when a value corresponding to the return operation of the steering device is equal to or greater than a predetermined threshold, and when the road surface gradient of the uphill road is large, than when it is not. Is also configured to reduce the threshold.
According to the present invention configured as described above, when the road slope (uphill slope) of the uphill road is large, the threshold value for determining whether or not to execute the vehicle yaw control is reduced, so the road surface of the uphill road Vehicle yaw control can be effectively promoted when the gradient is relatively large.

In the present invention, preferably, the controller is configured to increase the yaw moment to be applied by the vehicle yaw control when the road surface gradient of the uphill road is large than when it is not.
According to the present invention configured as described above, when the road slope (uphill slope) of the uphill road is large, the yaw moment added by the vehicle yaw control is increased. Therefore, when the road slope of the uphill road is relatively large Vehicle yaw control can be effectively promoted.

In the present invention, it is preferable that the controller sets a yaw moment based on a target lateral jerk corresponding to the steering speed and the vehicle speed when the steering speed of the steering device becomes a predetermined threshold value or more, and The vehicle yaw control is executed so as to apply a moment to the vehicle.
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 to suppress the turning of the vehicle, and the vehicle can be quickly responsive to the steering operation of the driver. The behavior can be stabilized.

In the present invention, it is preferable that the controller has a change speed of a difference between a target yaw rate corresponding to a steering angle and a vehicle speed of the steering device and an actual yaw rate actually generated in the vehicle equal to or higher than a predetermined threshold value. In addition, the yaw moment is set based on the change speed, and the vehicle yaw control is executed so as to add the yaw moment to the vehicle.
According to the present invention configured as described above, when the steering wheel is operated on a low μ road such as a snow-capped road, for example, immediately in response to a sudden change in the yaw rate difference due to the response delay of the actual yaw rate. A yaw moment in a direction that suppresses turning can be applied to the vehicle, and the vehicle behavior can be quickly stabilized in accordance with the driver's steering operation in a situation before the vehicle behavior becomes unstable.

  ADVANTAGE OF THE INVENTION According to this invention, in the vehicle control apparatus which performs the vehicle yaw control which adds a yaw moment to a vehicle, the vehicle yaw control suitable for it can be performed appropriately in consideration of the gradient of the road surface where a vehicle drive | works.

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. It is a block diagram which shows the electric constitution of the control apparatus of the vehicle by embodiment of this invention. It is a flowchart of the attitude | position control process by embodiment of this invention. It is a flowchart of the additional deceleration setting process by embodiment of this invention. 6 is a map showing the relationship between additional deceleration and steering speed according to an embodiment of the present invention. It is a flowchart of the target yaw moment setting process by embodiment of this invention. It is the map which showed the threshold value used in the target yaw moment setting process by embodiment of this invention. It is the map which showed the gain used in the target yaw moment setting process by embodiment of this invention.

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

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

  In FIG. 1, the code | symbol 1 shows the vehicle carrying the vehicle control apparatus by this embodiment. An engine 4 is mounted on the vehicle body front portion of the vehicle 1 as a drive source for driving drive wheels (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. In the present embodiment, the engine 4 is a gasoline engine having a spark plug.

  The vehicle 1 mainly serves as a 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 the steering device. A steering angle sensor 8 that detects a steering angle, a vehicle speed sensor 10 that detects a vehicle speed, a yaw rate sensor 12 that detects a yaw rate, and a gradient sensor 11 that detects a road surface gradient (road surface inclination) on which the vehicle 1 travels. A vehicle longitudinal acceleration sensor 13 for detecting the longitudinal acceleration (longitudinal acceleration) of the vehicle 1. Each of these sensors outputs a detected value to a PCM (Power-train Control Module) 14.

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

  The brake control system 18 calculates the hydraulic pressure supplied independently to each wheel cylinder and brake caliper 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, The rotational speed of the hydraulic pump 20 and the opening degree of the valve unit 22 are controlled in accordance with the hydraulic pressure.

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

  The PCM 14 according to the present embodiment is configured so that each part of the engine 4 is based on detection signals output from various sensors that detect the operating state of the engine 4 in addition to the detection signals of the sensors 8, 10, 11, 12, 13, and 24 described above. (Typically, spark plug 26. In addition, control is performed to control the throttle valve, turbocharger, variable valve mechanism, fuel injection valve, EGR device, etc.) and brake control system 18. Output a signal.

  Each of the PCM 14 and the brake control system 18 includes one or more processors, various programs interpreted and executed on the processors (a basic control program such as an OS, and an application program that is activated on the OS and realizes a specific function. ), And a computer having 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 a “controller” in the present invention.

<Vehicle attitude control>
Next, specific control contents executed by the vehicle control device will be described. First, an overall flow of the attitude control process performed by the vehicle control apparatus in the embodiment of the present invention will be described with reference to FIG. 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 started when the ignition of the vehicle 1 is turned on and the PCM 14 is powered on, 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 S <b> 1, the PCM 14 acquires various information 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 road surface gradient detected by the gradient sensor 11, and the vehicle longitudinal acceleration sensor 13 detected. The detection signals output by the various sensors of the vehicle 1 are acquired, including the longitudinal acceleration and the like.

Next, in step S <b> 2, the PCM 14 executes an additional deceleration setting process and sets an additional deceleration to be added to the vehicle 1.
Subsequently, in step S <b> 3, the PCM 14 executes a target yaw moment setting process and sets a target yaw moment to be applied to the vehicle 1.

  Next, in step S4, the PCM 14 controls the engine 2 so as to add the additional deceleration set in step S2 to the vehicle 1. In this case, the PCM 14 decreases the output torque of the engine 2 so as to add the set additional deceleration to the vehicle 1. Typically, the PCM 14 controls the spark plug 26 so as to retard the ignition timing in the engine 4 to reduce the output torque of the engine 2.

  In step S4, the brake control system 18 controls the brake device 16 so that the target yaw moment set in step S3 is applied 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 rotational speed of the hydraulic pump 20, and is set in the target yaw moment setting process in step S3 by referring to this map. The hydraulic pump 20 is operated at the rotational speed corresponding to the commanded yaw moment command value (for example, by increasing the power supplied to the hydraulic pump 20 to the rotational speed corresponding to the braking force command value, the hydraulic pump 20 Increase the number of revolutions).

  In addition, the brake control system 18 stores, for example, a map that prescribes the relationship between the yaw moment command value and the opening degree of the valve unit 22 in advance, 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 (for example, by increasing the power supplied to the solenoid valve, the opening of the solenoid valve is increased to the opening corresponding to the braking force command value). Adjust the braking force of the wheels. The brake control system 18 does not perform the control in step S4 when the target yaw moment is not set in step S3.

  After step S4 described above, 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. 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.

  As shown in FIG. 4, when the additional deceleration setting process is started, in step S11, the PCM 14 calculates a steering speed based on the steering angle acquired in step S1 of the behavior control process of FIG.

Next, in step S12, PCM 14 determines in turning operation of the steering wheel 6 (i.e. the steering angle (absolute value) in the increase) of and the steering speed whether a predetermined threshold value S ₁ or more.
As a result, when the operation in and steering speed cut is the threshold value S ₁ or more, the process proceeds to step S13, PCM 14 sets the deceleration with based on the steering speed. This additional deceleration is a deceleration to be added to the vehicle 1 in accordance with the steering operation in order to accurately realize the vehicle behavior intended by the driver.

Specifically, the PCM 14 sets an additional deceleration corresponding to the steering speed calculated in step S11 based on the relationship between the steering speed and the additional deceleration shown in the map of FIG.
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 zero. That is, when the steering speed is less than the threshold value S _1, PCM 14 does not perform the control for adding the deceleration of the vehicle 1 based on the steering operation (specifically, reduction of the output torque of the engine 4).
On the other hand, when the steering speed is the threshold value S ₁ or more, according to the steering speed increases, additional deceleration corresponding to the steering speed is asymptotic to a predetermined upper limit value D _max. That is, the additional deceleration increases as the steering speed increases, and the increase rate of the increase amount decreases. This upper limit value D _max is set to such a deceleration that the driver does not feel that there is a control intervention even if a 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 larger than the threshold value S ₁ , the additional deceleration is maintained at the upper limit value D _max .
After step S13, the PCM 14 ends the additional deceleration setting process and returns to the main routine.

Also, not in turning operation of the steering wheel 6 (i.e. steering angle in a constant or decreases) in step S12 or if the steering speed is less than the threshold value S _1, PCM 14 will terminate the addition deceleration setting process, the main routine Return to.

  The PCM 14 reduces the output torque of the engine 4 in step S4 of the attitude control process of FIG. 3 so as to realize the additional deceleration set based on the increase speed of the steering angle in the additional deceleration setting process described above. As described above, when the steering wheel 6 is cut, the output torque of the engine 4 is decreased based on the steering speed to increase the vertical load of the front wheel 2, which is favorable for the cutting operation by the driver. The behavior of the vehicle 1 can be controlled with responsiveness.

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

  6 is a flowchart of the target yaw moment setting process according to the embodiment of the present invention, FIG. 7 is a map showing threshold values used in the target yaw moment setting process according to the embodiment of the present invention, and FIG. It is the map which showed the gain used in the target yaw moment setting process by embodiment of invention.

  As shown in FIG. 6, when the target yaw moment setting process is started, in step S31, the PCM 14 determines the target yaw rate and the target lateral jerk based on the steering angle and the 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 a target lateral jerk based on the steering speed and the vehicle speed.

  Next, in step S32, the PCM 14 sets a 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 process according to the road gradient acquired in step S1, and sets the target yaw moment in the following process. The gain used for this is set.

First, the setting of threshold values Y ₁ and S ₃ will be specifically described with reference to FIG. These threshold values Y ₁ and S ₃ are used in different determinations in step S34 (including S36) and step S37, which will be described later. Basically, the threshold values Y ₁ and S ₃ are predetermined values corresponding to the switchback operation of the steering wheel 6. If the parameter is the threshold value Y ₁ and S ₃ above, the target yaw when used to set the target yaw moment to be given to the vehicle (i.e. a predetermined parameter is less than the threshold value Y ₁ and S ₃ Moment is not set). In the description of FIG. 7, “threshold value Y ₁ ” and “threshold value S ₃ ” may be simply referred to as “threshold value”.

  FIG. 7 is a map that defines threshold values used to set the target yaw moment in the 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 indicates the road surface gradient, and the vertical axis indicates the threshold value. In the road surface gradient shown on the horizontal axis in FIG. 7, “0” indicates a flat road, and the right side of “0” indicates a road surface gradient (uphill) on an uphill road (uphill). The left side shows the road gradient (downhill) on the downhill road (downhill). Specifically, on an uphill road, the road surface gradient increases as it goes to the right side of the figure, that is, the degree of the upward gradient increases. On the other hand, on a downhill road, the road surface gradient (absolute value) increases as it goes to the left in the figure, that is, the degree of the downward gradient increases. In principle, the road surface gradient is expressed by an angle (°) of the road surface with respect to a horizontal plane, or by a ratio (%) of a vertical distance to a predetermined horizontal distance.

  As shown in FIG. 7, the map is basically defined so that the threshold is larger on the downhill road than on the flat road and the uphill road. By applying such a threshold value, when traveling on a downhill road, a predetermined parameter (in other words, depending on the turning state of the vehicle 1) than when traveling on a flat road or traveling on an uphill road. The predetermined parameter) is not more than a threshold value. As a result, it is less likely that the target yaw moment is set in the following processing. That is, when traveling on a downhill road, the control (vehicle yaw control) that applies the yaw moment reverse to the actual yaw rate to the vehicle 1 by the brake device 16 is suppressed, in other words, the vehicle yaw control becomes difficult to execute. . Thereby, it becomes possible to appropriately suppress the control intervention from being excessive by executing the vehicle yaw control when traveling on the downhill road.

  In particular, on downhill roads, the map is defined so that the threshold value increases as the road surface gradient (absolute value) increases as an overall tendency. More specifically, on a downhill road, if the road surface gradient (absolute value) is less than a first predetermined value (about 0.5 to 2%), the same threshold value as that for a flat road is applied, and the road surface gradient (absolute value) is the first. When the road surface gradient (absolute value) is greater than a predetermined value and less than the second predetermined value (about 5 to 10%), the threshold value increases. When the road surface gradient (absolute value) is greater than or equal to the second predetermined value, a relatively large threshold value is obtained. It is designed to be applied uniformly. As a result, when traveling downhill, the vehicle yaw control is ensured to be executed when the road surface gradient (absolute value) is small, and the degree of suppression of the vehicle yaw control is increased as the road surface gradient (absolute value) increases. Can do.

  On the other hand, the map shown in FIG. 7 is defined such that the threshold is smaller on the uphill road than on the flat road and the downhill road. By applying such a threshold value, a condition that the predetermined parameter corresponding to the switch-back operation of the steering wheel 6 is equal to or greater than the threshold value when traveling on an uphill road or traveling on a downhill road is satisfied. It becomes easy. As a result, there is a high possibility that the target yaw moment is set in the following processing. That is, when traveling on an uphill road, the vehicle yaw control is promoted, in other words, the vehicle yaw control is easily performed. As a result, when traveling on an uphill road, it is possible to appropriately ensure the function of improving the responsiveness of the vehicle 1 by the vehicle yaw control, that is, the function of quickly stabilizing the vehicle behavior according to the steering operation.

  In particular, on an uphill road, as a general tendency, a map is defined such that the threshold value decreases as the road surface gradient increases. More specifically, on an uphill road, when the road surface gradient is less than a third predetermined value (about 0.5 to 2%), the same threshold value as that for a flat road is applied, and the road surface gradient is equal to or greater than a third predetermined value and is a fourth predetermined value. If it is less than (about 5 to 10%), the threshold value decreases as the road surface gradient increases, and a relatively small threshold value is uniformly applied when the road surface gradient is equal to or greater than a fourth predetermined value. Accordingly, when traveling on an uphill road, the degree of promoting vehicle yaw control can be increased as the road surface gradient increases.

FIG. 7 schematically shows the tendency of both the threshold values Y ₁ and S ₃ according to the road surface gradient. Actually, according to such a tendency, the threshold values Y ₁ and Y according to the road surface gradient are shown. each S ₃ are set separately. That is, for each of the threshold value Y ₁ and the threshold value S ₃ used in different determinations in step S34 (including S36) and step S37, a map corresponding to the road gradient is defined. In principle, the threshold value Y ₁ and the threshold value S ₃ are defined. Is set to a different value. Further, these threshold values Y ₁ and S ₃ are set by adaptation according to the characteristics of the vehicle 1 to which the vehicle yaw control is applied by conducting simulations and experiments in advance (the same applies to the gain described later). is there).

  Next, with reference to FIG. 8, the gain used for setting the target yaw moment in the embodiment of the present invention will be specifically described. FIG. 8 is a map defining the gain according to the embodiment of the present invention. This map is created in advance and stored in a memory or the like. In FIG. 8, the horizontal axis indicates the road surface gradient, and the vertical axis indicates the gain. This gain is set to a value corresponding to the road surface gradient, and is used to multiply a target yaw moment calculated by a method described later. That is, the value obtained by multiplying the gain is used as the target yaw moment to be finally applied.

  As shown in FIG. 8, basically, the map is defined so that the gain is smaller on the downhill road than on the flat road and the uphill road (in particular, the gain is 1 or less). By applying such a gain, the target yaw moment becomes smaller when traveling on a downhill road than when traveling on a flat road or traveling on an uphill road. As a result, vehicle yaw control is substantially suppressed when traveling downhill. This also makes it possible to appropriately suppress an excessive control intervention by executing the vehicle yaw control when traveling downhill.

  In particular, on downhill roads, the map is defined so that the gain decreases from 1 as the road surface gradient (absolute value) increases as an overall tendency. More specifically, on a downhill road, when the road surface gradient (absolute value) is less than a first predetermined value, the same gain as that of a flat road is applied, and the road surface gradient (absolute value) is greater than or equal to a first predetermined value and less than a second predetermined value. Then, as the road surface gradient (absolute value) increases, the gain decreases. When the road surface gradient (absolute value) exceeds the second predetermined value, a relatively small gain is uniformly applied. As a result, when traveling on a downhill road, it is possible to increase the degree of suppressing the vehicle yaw control as the road surface gradient (absolute value) increases while securing the vehicle yaw control when the road surface gradient (absolute value) is small. .

  On the other hand, the map shown in FIG. 8 is defined so that the gain is larger on the uphill road than on the flat road and the downhill road (in particular, the gain is 1 or more). By applying such a gain, the target yaw moment becomes larger when traveling on an uphill road than when traveling on a flat road or traveling on a downhill road. As a result, vehicle yaw control is substantially promoted when traveling on an uphill road. This also makes it possible to appropriately ensure a quick vehicle behavior stabilization function according to a steering operation by vehicle yaw control when traveling on an uphill road.

  In particular, on an uphill road, as a general trend, a map is defined such that the gain increases from 1 as the road surface gradient increases. More specifically, on an uphill road, the same gain as that of a flat road is applied when the road surface gradient is less than a third predetermined value, and the gain is increased as the road surface gradient increases when the road surface gradient is greater than or equal to a third predetermined value and less than a fourth predetermined value. When the road surface gradient is equal to or greater than the fourth predetermined value, a relatively large gain is uniformly applied. Accordingly, when traveling on an uphill road, the degree of promoting vehicle yaw control can be increased as the road surface gradient increases.

  In the processing described later, target yaw moments are set separately in different steps S35 and S38, but different values of gain are used in setting the target yaw moments in these different steps S35 and S38. Also good.

  In addition, the magnitude of the road surface gradient may change during the steering wheel 6 return operation. Preferably, the threshold value and the gain to be applied are not changed in accordance with the road surface gradient that changes. It is good. That is, after the predetermined parameter according to the switchback operation of the steering wheel 6 exceeds the threshold value and the vehicle yaw control is started, the threshold value and gain are not changed without changing the threshold value and gain according to the change in the road surface gradient. It is better to apply a fixed value as In particular, the threshold value and the gain are set based on the road surface gradient when the steering wheel 6 switching operation is started, and the threshold value and the gain are changed according to the change of the road surface gradient during the vehicle yaw control. Instead, the threshold and gain set in this way should be applied consistently.

Returning to FIG. 6, the description of the processing after step S <b> 34 is resumed. In step S34, the PCM 14 is in the operation of turning back the steering wheel 6 (ie, the steering angle is decreasing), and the change rate Δγ ′ of the yaw rate difference obtained by time differentiation of the yaw rate difference Δγ is the threshold value Y _1. It is determined whether it is above. PCM14 as the threshold Y _1, using the value set in step S33.

As a result, 'when is the threshold value Y ₁ or more, the process proceeds to step S35, PCM 14 is change rate Δγ in the yaw rate difference' change rate Δγ in and yaw rate difference in the returning operation and, on the gain set in step S33 Based on this, a yaw moment reverse to the actual yaw rate of the vehicle 1 is set as the target yaw moment. Specifically, the PCM 14 calculates the magnitude of the reference target yaw moment by multiplying a predetermined coefficient by the change rate Δγ ′ of the yaw rate difference, and further increases the gain with respect to the reference target yaw moment. By multiplying, the magnitude of the target yaw moment to be applied to the vehicle 1 is calculated.

On the other hand, if it is determined in step S34 that the steering wheel 6 is not being switched back (that is, the steering angle is constant or increasing), the process proceeds to step S36 where the PCM 14 sets the actual yaw rate as the target yaw rate change rate Δγ ′. It is determined whether or not the direction is greater than the yaw rate (that is, the direction in which the behavior of the vehicle 1 is oversteered) and the change rate Δγ ′ of the yaw rate difference is equal to or greater than the threshold Y ₁ . Specifically, when the yaw rate difference is decreasing under a situation where the target yaw rate is equal to or higher than the actual yaw rate, or when the yaw rate difference is increasing under a situation where the target yaw rate is less than the actual yaw rate, The change rate Δγ ′ of the yaw rate difference is determined to be a direction in which the actual yaw rate is greater than the target yaw rate.

As a result, when the change rate Δγ in the yaw rate difference is 'change rate Δγ of it and the yaw rate difference in the direction of the actual yaw rate is greater than the target yaw rate' is the threshold value Y ₁ or more, the process proceeds to step S35, PCM 14, similarly to the above Thus, based on the change rate Δγ ′ of the yaw rate difference and the gain set in step S33, the yaw moment that is the reverse of the actual yaw rate of the vehicle 1 is set as the target yaw moment.

After step S35, or if the change rate Δγ in the yaw rate difference 'change rate Δγ if yaw rate difference actual yaw rate is not larger direction than the target yaw rate' is less than the threshold value Y ₁ at step S36, 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. PCM14 as the threshold S _3, using the value set in step S33.

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 includes a target lateral jerk calculated in step S31, based on the gain set in step S33, the vehicle 1 A yaw moment reverse to the actual yaw rate is set as the second target yaw moment. Specifically, the PCM 14 calculates the magnitude of the second target yaw moment serving as a reference by multiplying the target lateral jerk by a predetermined coefficient, and gains relative to the second target yaw moment serving as the reference. Is further multiplied to calculate the magnitude of the second target yaw moment to be applied to the vehicle 1.

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 one 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 step S35 and step S38 (that is, if both the processes in 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.

<Effect>
Next, functions and effects of the vehicle control apparatus according to the embodiment of the present invention will be described.

  According to the present embodiment, the PCM 14 suppresses the vehicle yaw control when the vehicle 1 is traveling on the downhill road when the steering wheel 6 is switched back, than when it is not. Thereby, it can suppress appropriately that control intervention will be in an excessive state by performing vehicle yaw control at the time of downhill road driving. That is, when traveling on a downhill road, the load applied to the front wheel 2 (turning wheel) is relatively large and the restoring moment of the front wheel 2 is large, so that the vehicle in a turning state tends to be returned in the straight direction. Therefore, in this embodiment, by suppressing the vehicle yaw control when traveling downhill, it is possible to appropriately suppress the vehicle 1 from returning excessively in the straight direction due to the addition of the yaw moment by the control.

Further, according to the present embodiment, the PCM 14 has a value (yaw rate difference change speed Δγ ′ or steering speed) corresponding to the switching back operation of the steering wheel 6 equal to or greater than a predetermined threshold (threshold Y ₁ or S ₃ ). Vehicle yaw control is executed when the road slope is high, and the threshold value is increased when the road slope (down slope) of the downhill road is large. Therefore, the vehicle yaw control is effectively suppressed when the road slope of the downhill road is relatively large. be able to.

  Further, according to the present embodiment, when the road slope (down slope) of the downhill road is large, the PCM 14 reduces the yaw moment added by the vehicle yaw control by the gain, so that the road slope of the downhill road is relatively large. Sometimes vehicle yaw control can be effectively suppressed.

  On the other hand, according to the present embodiment, the PCM 14 promotes the vehicle yaw control when the vehicle 1 is traveling on the uphill road when the steering wheel 6 is switched back, than when it is not. As a result, when traveling on an uphill road, it is possible to appropriately ensure the function of improving the responsiveness of the vehicle 1 by the vehicle yaw control, that is, the function of quickly stabilizing the vehicle behavior according to the steering operation. That is, when traveling on an uphill road, since the load applied to the front wheel 2 (turning wheel) is relatively small and the restoring moment of the front wheel 2 is small, a yaw moment similar to that when traveling on a flat road is applied by vehicle yaw control. However, in the present embodiment, the vehicle yaw control is promoted when traveling on an uphill road, so that the response improvement function of the vehicle 1 by the vehicle yaw control is improved. Can be secured appropriately.

Further, according to the present embodiment, the PCM 14 has a value (yaw rate difference change speed Δγ ′ or steering speed) corresponding to the switching back operation of the steering wheel 6 equal to or greater than a predetermined threshold (threshold Y ₁ or S ₃ ). The vehicle yaw control is executed when the road slope is high, and the threshold value is reduced when the road slope (uphill slope) of the uphill road is large. Therefore, the vehicle yaw control is effectively promoted when the road slope of the uphill road is relatively large. be able to.

  According to the present embodiment, the PCM 14 increases the yaw moment added by the vehicle yaw control by the gain when the road slope (uphill slope) of the uphill road is large. Therefore, the road slope of the uphill road is relatively large. Sometimes vehicle yaw control can be effectively promoted.

On the other hand, according to the present embodiment, PCM 14, when the acquired steering speed on the basis of the detected value of the steering angle sensor 8 becomes the threshold S ₃ above, sets the target lateral jerk based on the steering speed and the vehicle speed, A yaw moment to be applied in the vehicle yaw control is set based on the target lateral jerk. Thereby, a yaw moment having a magnitude corresponding to the speed of the steering operation of the driver can be applied in a direction to suppress the turning of the vehicle 1, and the vehicle behavior can be quickly stabilized according to the steering operation of the driver. .

In addition, according to the present embodiment, the PCM 14 determines that the change rate of the difference between the actual yaw rate actually generated in the vehicle 1 and the target yaw rate set based on the detected value of the steering angle sensor 8 is equal to or greater than the threshold Y _1. Then, the yaw moment to be applied in the vehicle yaw control is set based on the change speed. As a result, when the steering wheel is operated on a low-μ road such as a snowy road, the vehicle can immediately control the yaw moment in a direction that suppresses turning in response to a sudden change in the yaw rate difference caused by the response delay of the actual yaw rate. 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>
Next, a modification of this embodiment will be described. A plurality of modifications shown below can be implemented in combination with each other as appropriate.

(Modification 1)
In the above-described embodiment, the threshold value and the gain are changed stepwise according to the magnitude of the road surface gradient (see FIGS. 7 and 8). However, in the modification, the threshold value and the gain are continuously applied over the entire area of the road surface gradient. May be changed. In this modified example, on downhill roads, the threshold value is increased and the gain is reduced as the road surface gradient (absolute value) increases over the entire road surface gradient, and on the uphill road, the road surface gradient is extended over the entire region. As the road surface gradient increases, the threshold value is decreased and the gain is increased.

(Modification 2)
In the above-described embodiment, the vehicle yaw control is suppressed by changing both the threshold for determining whether or not to execute the vehicle yaw control and the yaw moment added by the vehicle yaw control (changed by the gain). However, in the modified example, the vehicle yaw control may be suppressed or promoted by changing only one of the threshold value and the yaw moment.

(Modification 3)
In the above-described embodiment, the road surface gradient is directly acquired using the gradient sensor 11. However, in the modification, the road surface gradient may be obtained using the vehicle longitudinal acceleration sensor 13 instead of the gradient sensor 11. In this case, the road surface gradient can be obtained based on the difference between the target acceleration obtained from the accelerator opening (accelerator pedal depression amount) and the vehicle speed and the longitudinal acceleration (actual acceleration) detected by the vehicle longitudinal acceleration sensor 13. . Specifically, when the actual acceleration is smaller than the target acceleration, it can be determined that the road is an uphill road, and when the actual acceleration is larger than the target acceleration, it can be determined that the road is a downhill road. Based on the difference from the target acceleration, the value of the road slope (uphill / downhill) of the uphill road or downhill road can be obtained.

(Modification 4)
In the embodiment described above, both the target yaw moment setting based on the change rate Δγ ′ of the yaw rate difference (step S35 in FIG. 6) and the target yaw moment setting based on the target lateral jerk (step S38 in FIG. 6) are executed. However, in the modification, only one of these two target yaw moment settings may be executed.

(Modification 5)
In the above-described embodiment, the example in which the rotation angle of the steering column coupled to the steering wheel 6 (the angle detected by the steering angle sensor 8) is used as the steering angle of the vehicle 1 has been described. Instead of the rotation angle or together with the rotation angle of the steering column, various state quantities in the steering system (rotation angle of the motor that applies assist torque, rack displacement in the rack and pinion, etc.) may be used as the steering angle of the vehicle 1. Good.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Front wheel 4 Engine 6 Steering wheel 8 Steering angle sensor 10 Vehicle speed sensor 11 Gradient sensor 12 Yaw rate sensor 13 Vehicle longitudinal acceleration sensor 14 PCM
16 Brake device 18 Brake control system

Claims (8)

A vehicle control device having a steering device, a brake device capable of applying different braking forces to left and right wheels, and a controller,
The controller is
Based on the return operation of the steering device, vehicle yaw control is performed to control the brake device so as to add a yaw moment that is reverse to the yaw rate generated in the vehicle to the vehicle,
A vehicle control device configured to suppress the vehicle yaw control when the vehicle is traveling on a downhill road during a return operation of the steering device than when it is not.   The controller executes the vehicle yaw control when a value corresponding to a return operation of the steering device is equal to or greater than a predetermined threshold, and when the road slope of the downhill road is large, the threshold is higher than when it is not. The vehicle control device according to claim 1, wherein the vehicle control device is configured to increase the size of the vehicle.   3. The vehicle control device according to claim 1, wherein the controller is configured to reduce a yaw moment to be added by the vehicle yaw control when the road slope of the downhill road is large than when it is not. . A vehicle control device having a steering device, a brake device capable of applying different braking forces to left and right wheels, and a controller,
The controller is
Based on the return operation of the steering device, vehicle yaw control is performed to control the brake device so as to add a yaw moment that is reverse to the yaw rate generated in the vehicle to the vehicle,
The vehicle control device is configured to promote the vehicle yaw control when the vehicle is traveling on an uphill road during the return operation of the steering device than when it is not.   The controller executes the vehicle yaw control when a value corresponding to a return operation of the steering device is equal to or greater than a predetermined threshold, and when the road surface gradient of the uphill road is large, the threshold is higher than when it is not. The vehicle control device according to claim 4, wherein the vehicle control device is configured to reduce the size of the vehicle.   6. The vehicle control device according to claim 4, wherein the controller is configured to increase a yaw moment to be added by the vehicle yaw control when the road surface gradient of the uphill road is large than when it is not. .   The controller sets the yaw moment based on the target lateral jerk according to the steering speed and the vehicle speed when the steering speed of the steering device becomes a predetermined threshold or more, and applies the yaw moment to the vehicle. The vehicle control device according to any one of claims 1 to 6, wherein the vehicle yaw control is executed so as to be added.   When the change speed of the difference between the target yaw rate according to the steering angle and the vehicle speed of the steering device and the actual yaw rate actually generated in the vehicle becomes equal to or greater than a predetermined threshold value, the controller The vehicle control device according to any one of claims 1 to 6, wherein the vehicle yaw control is performed so as to set the yaw moment based on the yaw moment and to add the yaw moment to the vehicle. .

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