JP4675176B2 - Vehicle behavior control device - Google Patents

Description

  The present invention relates to a vehicle behavior control device that controls a skid state suppression control by controlling a braking force generated by each wheel.

Conventionally, in a vehicle behavior control apparatus having behavior control means for estimating a side slip state of a vehicle based on the detected side acceleration and yaw rate, and executing a side slip state suppression control when the side slip state is estimated, a steering angle Detecting means, means for determining a friction coefficient of the road surface, means for determining a first parameter corresponding to a deviation between the slip angle of the front wheel and the slip angle of the rear wheel based on the steering angle and the yaw rate, and the first Grip state determination means for determining whether or not the vehicle is in a grip state with respect to the road surface based on the parameter and the friction coefficient of the road surface, and when the vehicle is determined to be in the grip state, side slip state suppression control by the behavior control means 2. Description of the Related Art A vehicle behavior control apparatus having a means for prohibiting the movement is known (see, for example, Patent Document 1).
JP 09-123888 A

  By the way, in this type of vehicle behavior control device, as a precondition for performing the skid state suppression control, a non-grip state in which the grip state of the wheel with respect to the road surface does not satisfy a predetermined standard is detected as in the prior art described above. By permitting the skid state suppression control only when the grip state is detected, the skid state suppression control is prevented from being executed in an unnecessary scene.

  Here, the ideal non-grip state detection condition is a condition that is robust against noise and the like, and the non-grip state is surely detected in a scene that requires side slip state suppression control (for example, during an emergency avoidance operation). While detected (a control permission state is formed), a relatively large actual lateral acceleration occurs when a side slip state suppression control is unnecessary (for example, not only during normal driving but also during high-speed driving on a circuit road) In the scene), the non-grip state is not detected.

  Therefore, an object of the present invention is to provide a vehicle behavior control device that can realize appropriate skid state suppression control by optimally setting the non-grip state detection condition.

In order to achieve the above object, a first aspect of the present invention provides a vehicle behavior control device that performs a skid state suppression control to suppress an undesirable skid state of a vehicle.
A lateral acceleration converted value calculating means for calculating a lateral acceleration converted value by converting the detected vehicle state quantity;
An actual lateral acceleration detecting means for detecting the actual lateral acceleration;
A non-grip state detecting means for detecting a non-grip state of the vehicle with respect to the road surface, and performing switching from the execution prohibited state to the execution permitted state of the skid state suppression control when the non-grip state is detected;
The non-grip state is a positive or negative sign representing the vehicle turning direction in which the lateral acceleration converted value and the actual lateral acceleration obtained from each means are the same, and the magnitude of the lateral acceleration converted value and the actual lateral acceleration are respectively It is characterized in that it is detected as one condition when it is larger than the threshold value.

A second invention, in the vehicle behavior control device according to the invention the first, the lateral acceleration conversion value, the first lateral acceleration conversion value is calculated on the basis of the output value and the output value of the vehicle speed sensor of the steering angle sensor And a second lateral acceleration conversion value calculated based on the output value of the yaw rate sensor and the output value of the vehicle speed sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle behavior control apparatus which can implement | achieve appropriate skid state suppression control can be obtained by setting a non-grip state detection condition optimally.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a main configuration of a vehicle behavior control device according to the present invention. The vehicle behavior control device 10 is mainly configured with an ECU 20 that controls the brake device 40 disposed on each wheel of the vehicle, and controls a braking force generated by each wheel to perform a skid state suppression control. Do. For example, in the case of oversteer (vehicle spin), the skid state suppression control generates an outward moment by generating braking force on the front outer wheel and reduces the cornering force. This is a control to reduce. In addition, for understeer caused by slipping of the front wheels (drive wheels), control is performed to reduce the moment in the spin direction by, for example, generating an inward moment by generating a braking force on the front inner wheel as well as reducing the engine torque. is there. Note that the present invention is not limited to such a skid state suppression control method, and can be applied to any appropriate skid state suppression control. Further, the braking force does not necessarily have to be generated by the mechanical braking force (braking force by hydraulic control) by the brake device 40, and can be replaced as long as the braking force can be adjusted individually for each wheel. Alternatively or additionally, regenerative braking force (in the case of a hybrid vehicle) or the like may be used. Further, the skid state suppression control is not limited to that realized by controlling the braking force, but can be realized by controlling the driving force of an engine or the like or the driving force of an electric motor in addition to or instead of those. Further, it may be realized by controlling the steering amount (intervening steering).

  The side slip state suppression control is executed on the precondition that a flag representing a non-grip state is set, as will be described in detail below. Accordingly, in a state where the flag indicating the non-grip state is not set, the skid state suppression control is prohibited, and the vehicle state (for example, the slip angle and the slip speed equal to or higher than a predetermined threshold at which the skid state suppression control is to be started). Etc.), the skid state suppression control is not executed.

  As will be described in detail below, the present invention has a main feature in a setting mode of a flag indicating a non-grip state (execution prohibition condition or execution permission condition setting condition of skid state suppression control). Hereinafter, the characteristic configuration of the present invention will be described in several embodiments.

  FIG. 2 is a block diagram illustrating a main configuration of the ECU 20 according to the first embodiment. The ECU 20 is configured as a microcomputer including a CPU, a ROM, a RAM, and the like connected to each other via a bus (not shown). The ECU 20 includes a steering angle lateral acceleration converted value calculation unit 90, a yaw rate lateral acceleration converted value calculation unit 92, a non-grip state detection unit 94, and a control unit 96.

The ECU 20 includes a signal indicating the steering angle from the steering angle sensor 30 (steering angle signal), a signal indicating the vehicle speed based on the output value of the wheel speed sensor 32 disposed on each wheel (vehicle speed signal), and a vehicle body from the yaw rate sensor 34. A signal indicating the yaw rate γ (yaw rate signal) and a signal indicating the lateral acceleration (actual lateral acceleration) Gy [m / s ² ] of the vehicle body are input from the lateral acceleration sensor 36 provided substantially at the center of gravity of the vehicle body. The

In the steering angle lateral acceleration converted value calculation unit 90 (hereinafter referred to as “first lateral acceleration conversion unit 90”), the first lateral acceleration converted value StrG [m / s ² ] is calculated based on the steering angle signal and the vehicle speed signal. Calculated. The first lateral acceleration converted value StrG may be calculated by a map in consideration of, for example, the minimum turning radius of the vehicle.

Further, the yaw rate lateral acceleration converted value calculation unit 92 (hereinafter referred to as “second lateral acceleration conversion unit 92”) calculates the second lateral acceleration converted value YawG [m / s ² ] based on the yaw rate signal and the vehicle speed signal. Calculated. The second lateral acceleration converted value YawG may be derived, for example, by multiplying the yaw rate γ by the vehicle speed V (that is, YawG = γ × V). Note that the various signals input to the first lateral acceleration conversion unit 90 and the second lateral acceleration conversion unit 92 may have been subjected to appropriate preprocessing (filter processing or the like).

  These converted values StrG and YawG are calculated with the left turning direction of the vehicle as positive, like the polarity of the output value of the lateral acceleration sensor 36. The first and second lateral acceleration converted values StrG and YawG are input to the non-grip state detection unit 94 together with the lateral acceleration Gy for each predetermined period. Note that the lateral acceleration Gy input to the non-grip state detection unit 94 may be subjected to appropriate preprocessing (filter processing or the like).

  In the non-grip state detection unit 94, the first lateral acceleration conversion value StrG from the first lateral acceleration conversion unit 90, the second lateral acceleration conversion value YawG from the second lateral acceleration conversion unit 92, and the lateral acceleration Gy are 3 in total. A non-grip state is detected using two parameters. When the non-grip state is detected, a flag indicating the non-grip state is set to 1, and the skid state suppression control using the brake device 40 by the control unit 96 can be executed until the flag is reset to zero. become. The non-grip state is a state in which the grip state of the vehicle with respect to the road surface is lost, and the detection method will be described below with reference to FIG.

  Referring to FIG. 3, in the non-grip state detection unit 94, the magnitude (absolute value) of the first lateral acceleration converted value StrG is larger than the predetermined threshold Thr1 (YES in Step 100), and the magnitude of the lateral acceleration Gy ( (Absolute value) is larger than the predetermined threshold value Thr0 (YES in step 110), and the magnitude (absolute value) of the second lateral acceleration converted value YawG is larger than the value obtained by adding the magnitude of the lateral acceleration Gy to the predetermined threshold value Thr2. If it is larger (YES in step 120), a non-grip state is detected (step 130). As a result, the flag is set to a value 1 indicating a non-grip state.

  On the other hand, if any of the above three conditions is denied, the non-grip state is not detected, that is, it is determined that the grip state is set (step 140). As a result, the flag is maintained at a value 0 indicating the grip state, and the state in which the skid state suppression control is prohibited is maintained.

  By the way, as described above, the ideal non-grip state detection condition is a condition that is robust against noise and the like, and the non-grip state is reliably detected in a scene that requires side slip state suppression control. Thus, the non-grip state is not detected in a scene where the skid state suppression control is unnecessary.

  In the present embodiment, as described above, the non-grip state is detected only when each of the three conditions is satisfied, so that a robust determination against noise or the like can be realized. In this embodiment, the threshold values are compared for each of the three parameters (StrG, YawG, Gy), and the non-grip state is not detected, but the two parameters (StrG, Gy) are detected. The respective threshold values are compared, and the parameter YawG is determined using a threshold value corresponding to the magnitude of the lateral acceleration Gy. This is because, in a situation where side slip state suppression control is required, the equivalent amount of rotation acceleration (YawG) of the vehicle with respect to the vehicle center is significantly larger than the equivalent amount of rotation acceleration (Gy) of the vehicle with respect to the turning center. Is based on the findings found by (see FIG. 4A). Therefore, in this embodiment, by setting a threshold value Thr2 having an appropriate value for the difference between the vehicle's rotational acceleration equivalent amount (YawG) and the vehicle's revolution acceleration equivalent amount (Gy), each of the three parameters (StrG , YawG, Gy) compared to the case where each threshold value is compared, it is possible to judge a scene that requires skid state suppression control with high accuracy, and as a result, an appropriate non-grip state that should allow skid state suppression control. Can be detected.

  FIG. 4 is a diagram showing how the parameters (StrG, YawG, Gy) change when the vehicle turns left, then turns right, and then goes straight. FIG. 4 (A) shows a skid condition. Fig. 4 (B) shows typical changes in parameters (StrG, YawG, Gy) that appear in scenes that require restraint control. Figure 4 (B) shows scenes that do not require skid state restraint control (relatively large lateral acceleration occurs. Shows the same change mode appearing in a scene where the grip state is maintained and the non-grip state should not be detected.

  As shown in FIG. 4B, the grip state is maintained in a scene where the side slip state suppression control is unnecessary, and the second lateral acceleration conversion value YawG (two-dot chain line) substantially coincides with the lateral acceleration Gy. It varies in the manner. Therefore, in the configuration in which the threshold value is compared for each of the three parameters (StrG, YawG, Gy) and the non-grip state is detected, the non-grip state is not detected even for such a waveform. As shown in FIG. 4B, relatively large threshold values Thr1 ′, Thr0 ′, Thr2 ′ (shown with the same value for convenience in this example, but may be different values) must be set. . However, with such threshold values Thr1 ′, Thr0 ′, and Thr2 ′, there is a possibility that the non-grip state may not be detected in a scene where the skid state suppression control as shown in FIG. Since StrG and Gy do not exceed the threshold values Thr1 ′ and Thr0 ′, the non-grip state is not detected.

  On the other hand, in this embodiment, by setting threshold values Thr1 and Thr0 smaller than threshold values Thr1 ′ and Thr0 ′, non-grip is required in a situation where skid state suppression control as shown in FIG. The state detection is reliably realized. On the other hand, in the scene where the side slip state suppression control is unnecessary as shown in FIG. 4B, the first lateral acceleration converted value StrG and the lateral acceleration G exceed the respective threshold values Thr1 and Thr0 (the two conditions are However, since the difference between the second lateral acceleration converted value YawG and the lateral acceleration G is small and does not exceed the threshold Thr2 (the remaining one condition is not satisfied), the skid state suppression control is unnecessary. It is possible to reliably prevent the non-grip state from being detected. In other words, according to the present embodiment, by newly introducing a threshold determination for the relationship (deviation) between the second lateral acceleration converted value YawG and the lateral acceleration G, the first lateral acceleration converted value StrG and the lateral acceleration G The thresholds Thr1 and Thr0 for each can be reduced, and the non-grip state is reliably detected in a scene where the skid state suppression control is required, while the non-grip state is not detected in a scene where the skid state suppression control is not required. Such a non-grip state detection condition can be established.

  The main configuration of the ECU 20 according to the second embodiment itself (other than the functions described below) may be the same as that in FIG. Hereinafter, the non-grip state detection condition according to the second embodiment will be described with reference to FIG.

  Referring to FIG. 4, in the non-grip state detection unit 94, the first lateral acceleration converted value StrG (not an absolute value, hereinafter the same) is larger than a predetermined positive threshold value Thr1 + (YES in step 200), and the lateral acceleration is detected. When Gy is larger than a predetermined positive threshold value Thr0 + (YES in step 210) and the second lateral acceleration conversion value YawG is larger than a predetermined positive threshold value Thr2 + (YES in step 220), a non-grip state Is detected (step 400). Thereby, the non-grip state in the left turn direction is detected (as a result, the flag is set to a value 1 indicating the non-grip state).

  On the other hand, if any of the above three conditions is denied, the process proceeds to step 300 and subsequent steps.

  As a process after step 300, in the non-grip state detection unit 94, the first lateral acceleration converted value StrG (not an absolute value, hereinafter the same) is smaller than a predetermined negative threshold value Thr1- (YES in step 200). When the acceleration Gy is smaller than a predetermined negative threshold value Thr0− (YES in step 210) and the second lateral acceleration conversion value YawG is smaller than a predetermined negative threshold value Thr2− (YES in step 220), A non-grip state is detected (step 400). Thereby, the non-grip state in the right turn direction is detected (as a result, the flag is set to a value 1 indicating the non-grip state).

  On the other hand, if any of the above three conditions is denied, the non-grip state in the right turn direction is not detected, that is, it is determined that the grip state is set (step 410). As a result, the flag is maintained at a value 0 indicating the grip state, and the state in which the skid state suppression control is prohibited is maintained.

  Here, regarding each threshold Thr * + and Thr * − (where * = 0, 1, 2), the positive sign threshold Thr * + has the same absolute value as the corresponding negative sign threshold Thr * −. It may be. That is, | Thr * + | = | Thr * − |. However, it may be a different value.

  In this example, based on the fact that each of the three parameters (StrG, YawG, Gy) should always indicate the same sign, ie the same turning direction, unless there is a disturbance such as a sensor failure, As described above, a condition in which each of the three parameters (StrG, YawG, Gy) has the same sign is added to the threshold determination for each of the three parameters (StrG, YawG, Gy).

  FIG. 6 is a diagram illustrating how each parameter (StrG, YawG, Gy) changes when the vehicle enters a left turn state, then a right turn state, and then a straight forward state when a yaw rate sensor failure occurs as an example. It is.

  In the example shown in FIG. 6, due to the failure of the yaw rate sensor, the second lateral acceleration converted value YawG (two-dot chain line) is a negative peak when the other parameters (StrG, Gy) become positive peaks. It has become. In this case, in the configuration in which each threshold value (positive threshold value) is compared with the magnitude (absolute value) of each of the three parameters (StrG, YawG, Gy) and the non-grip state is detected, FIG. ), Since each parameter (StrG, YawG, Gy) is sufficiently large, a non-grip state is detected.

  In contrast, in this embodiment, the codes of the three parameters (StrG, YawG, Gy) are taken into consideration, and the codes of the three parameters are the same, and the respective sizes are larger than a predetermined threshold value. By making this a condition, it is possible to prevent the non-grip state from being erroneously detected with respect to the waveform as shown in FIG. Thus, according to the present embodiment, it is possible to establish a non-grip state detection condition that is robust against disturbances such as sensor failure.

  This embodiment can be realized in combination with the first embodiment. In this case, for example, in Example 1, each of the three parameters (StrG, YawG, Gy) may be added under the condition that the signs are the same. Alternatively, in the second embodiment, it is determined in step 120 whether or not the second lateral acceleration conversion value YawG is larger than a positive threshold value (= lateral acceleration Gy + positive predetermined threshold value Thr2). It may be determined whether or not the acceleration conversion value YawG is smaller than a negative threshold (= lateral acceleration Gy + negative predetermined threshold Thr2).

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the most typical sensor mounted on an existing vehicle is disclosed as the detection means for various vehicle states (steering angle, vehicle speed, yaw rate, etc.), but other appropriate means are disclosed. Thus, the same vehicle state can be detected.

  Further, in the above-described embodiment, two lateral acceleration conversion values are used and two threshold values are set for each. However, any one of the lateral acceleration conversion values can be used, and 3 It is also possible to introduce more than one lateral acceleration conversion value.

  In the embodiment described above, it is also possible to add an appropriate condition other than the above-mentioned conditions as one condition when detecting the non-grip state.

  In the above-described embodiment, any appropriate condition may be used for the release condition after the non-grip state is detected, that is, the condition for resetting the flag to zero. For example, for simplicity, the flag may be reset to zero when the non-grip state is no longer detected.

It is a block diagram which shows the principal part structure of the vehicle behavior control apparatus which concerns on this invention. 1 is a block diagram illustrating a configuration of a main part of an ECU 20 according to a first embodiment. 6 is a flowchart illustrating detection conditions for a non-grip state according to the first embodiment. Fig. 4 (A) shows typical waveforms of each of the three parameters (StrG, YawG, Gy) that appear in a scene that requires side slip state suppression control, and Fig. 4 (B) does not require side slip state suppression control. It is a figure which shows the typical same waveform which appears in a various scene. 10 is a flowchart illustrating detection conditions for a non-grip state according to the second embodiment. It is a figure which shows the waveform of each three parameters (StrG, YawG, Gy) which may appear due to the failure of a yaw rate sensor, and FIG. 6 (A) shows the comparative example which determines a threshold value only by the absolute value of each parameter. FIG. 4B is a diagram illustrating the effectiveness of the threshold determination mode according to the second embodiment.

Explanation of symbols

10 Vehicle Behavior Control Device 20 ECU
30 Steering angle sensor 32 Wheel speed sensor 34 Yaw rate sensor 36 Lateral acceleration sensor 40 Brake device 90 Steering angle lateral acceleration conversion value calculation unit 92 Yaw rate lateral acceleration conversion value calculation unit 94 Non-grip state detection unit

Claims (2)

In a vehicle behavior control device that performs a skid state suppression control to suppress an undesirable skid state of a vehicle,
A lateral acceleration converted value calculating means for calculating a lateral acceleration converted value by converting the detected vehicle state quantity;
An actual lateral acceleration detecting means for detecting the actual lateral acceleration;
A non-grip state detecting means for detecting a non-grip state of the vehicle with respect to the road surface, and performing switching from the execution prohibited state to the execution permitted state of the skid state suppression control when the non-grip state is detected;
The non-grip state is a positive or negative sign representing the vehicle turning direction in which the lateral acceleration converted value and the actual lateral acceleration obtained from each means are the same, and the magnitude of the lateral acceleration converted value and the actual lateral acceleration are respectively A vehicle behavior control device, characterized in that the vehicle behavior control device is detected on the condition that it is greater than a threshold value. The lateral acceleration conversion value is calculated based on the first lateral acceleration conversion value calculated based on the output value of the steering angle sensor and the output value of the vehicle speed sensor, the output value of the yaw rate sensor, and the output value of the vehicle speed sensor. The vehicle behavior control device according to claim 1, further comprising: a second lateral acceleration converted value.

Images