JP2010221805A - Driving supporting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving supporting device 1 for controlling a vehicle C to hardly deviate from an adequate course without giving a sense of incongruity to a driver when there is the possibility of the contact of the vehicle C with an obstacle even in the case a road surface friction coefficient (a road surface μ) is low. <P>SOLUTION: The driving supporting device 1 supports driving while calculating the controlled variable of steering control or brake control to support the avoidance of an obstacle and executing the steering control or the brake control at a predetermined control starting timing in accordance with the controlled variable. It gives vibration to a steering wheel 3, determines whether the road surface μ is low, depending on the behavior of the vehicle or a variation of a steering angle resulting from the vibration, and corrects the controlled variable or the control starting timing when determining that the road surface μ is low. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a driving support device that supports driving in a direction in which an obstacle should be avoided.

  Detects and recognizes obstacles using radar mounted on the vehicle, determines whether there is a possibility of contact between the obstacle and the vehicle, and if it is determined that there is a possibility of contact, such as warning or steering An apparatus that supports driving to avoid contact between an obstacle and a vehicle by driving (driving support) has been proposed by the present applicant (see, for example, Patent Document 1).

JP 2006-131072 A

  In the conventional driving support device, when there is a possibility of contact between the obstacle and the vehicle, the vehicle is controlled so that it is difficult for the vehicle to deviate from the appropriate course. However, in a scene where the friction coefficient (road surface μ) of the road surface is low, When the control is performed, the driver may feel uncomfortable.

  Therefore, the present invention provides a vehicle that does not give a driver a sense of incongruity or gives a sense of incongruity when there is a possibility of contact between an obstacle and a vehicle even in a scene where the friction coefficient of the road surface (road surface μ) is low. An object of the present invention is to provide a driving support device capable of controlling the vehicle so that it is difficult to deviate from the appropriate course.

  The present invention calculates a control amount of steering control or brake control that supports avoidance of an obstacle, and performs driving support by supporting the driving by executing the steering control or brake control from the predetermined control start time with the control amount. The apparatus is characterized in that a steering wheel is vibrated, and the control amount or the control start time is corrected in accordance with a change amount of a vehicle behavior or a steering angle caused by the vibration.

  Not only will the driver be warned that the vehicle may come into contact with obstacles due to vibration of the steering wheel, but the wheel will steer as the steering wheel vibrates, resulting in vehicle behavior or steering angle. It is possible to measure and grasp the size of the road surface μ by utilizing the change of the road surface. For example, when the steering wheel is vibrated at a constant torque (control amount), the higher the road surface μ is, for example, the dry the road surface is, the smaller the amount of change in the wheel turning angle becomes. The amount of change in the steering angle (vehicle behavior) becomes smaller. Conversely, the lower the road surface μ, for example, the wetter the road surface, the greater the change amount of the wheel turning angle and the greater the change amount of the steering angle (vehicle behavior) of the steering wheel. By using these relationships, when the amount of change in the steering angle (vehicle behavior) corresponding to the case where the road surface μ is small is acquired from the vibration of the steering wheel, the control amount or the control start time is corrected. Thus, it is possible to control the vehicle so that it is difficult for the vehicle to deviate from the appropriate course without giving the passenger a sense of incongruity, or with less discomfort.

  Further, when the amount of change in the vehicle behavior or the steering angle is larger than a threshold value, it is preferable to make a correction to reduce the control amount or to advance the control start timing. When the change amount of the vehicle behavior or the steering angle is larger than the threshold value, the road surface μ is small, and the slip ratio of the wheel tends to increase. Accordingly, the control surface is reduced so as to suppress an increase in the slip ratio, or the control start time is advanced so that the target control can be performed even if the slip ratio is large, thereby increasing the road surface. Even when μ is small, it is possible to perform control that makes it difficult for the vehicle to deviate from an appropriate course.

  Further, when the amount of change in the vehicle behavior or the steering angle is larger than a threshold value, it is preferable to perform correction to moderate the change that rises from the control start timing and increases to the control amount. When the change amount of the vehicle behavior or the steering angle is larger than the threshold value, the road surface μ is small, and the slip ratio of the wheel tends to increase. Therefore, in order to suppress an increase in the slip ratio, the increase in the control amount is moderated so that even when the road surface μ is small, the control that makes it difficult for the vehicle to deviate from the appropriate course can be continued.

  In addition, it is preferable that the amplitude of the vibration increases as the possibility of contact between the vehicle and the obstacle increases, and the threshold increases as the amplitude of the vibration increases. The driver is warned that the vehicle may come into contact with the obstacle due to the vibration of the steering wheel. Then, as the possibility of the obstacle approaching the vehicle increases, the vibration amplitude is increased as the possibility increases, so that the driver can be surely alerted to the obstacle. Even if the vibration amplitude of the steering wheel is increased, the torque (control amount) that vibrates the steering wheel is increased, the turning angle of the wheel is increased, and the change amount of the steering angle (vehicle behavior) of the steering wheel is increased. Therefore, in order to determine whether or not the road surface μ is small in absolute value, it is preferable that the threshold value of the change amount of the vehicle behavior or the steering angle is also increased corresponding to the amplitude or the change amount.

  The threshold value is preferably smaller as the vehicle speed is higher. The higher the vehicle speed, the smaller the amplitude and the smaller the amount of change in the steering angle (vehicle behavior) of the steering wheel, even if an attempt is made to vibrate the steering wheel with the same torque. It is preferable that the threshold value is also reduced corresponding to the amplitude.

  Moreover, it is preferable that the said threshold value becomes so large that the said vehicle behavior or steering angle before the said vibration is large. As the vehicle behavior or the steering angle before the vibration increases, the amplitude tends to increase when the steering wheel is vibrated with the same torque, and the amount of change in the steering angle (vehicle behavior) of the steering wheel increases. It is preferable that the threshold value of the change amount of the vehicle behavior or the steering angle is also increased corresponding to the amplitude.

  According to the present invention, even in a scene where the friction coefficient (road surface μ) of the road surface is low, if there is a possibility of contact between the obstacle and the vehicle, the occupant is not discomforted or given less discomfort. It is possible to provide a driving support device that can be controlled so that it is difficult to deviate from an appropriate course.

It is a lineblock diagram of vehicles provided with a driving support device concerning an embodiment of the present invention. It is a flowchart of the driving assistance method implemented in the driving assistance apparatus which concerns on embodiment of this invention. It is a graph which shows threshold value a1, a2, a3 which determines whether it is a low micro road area | region set with respect to the vehicle behavior change (output amount) of the turning direction according to a steering warning control amount (input amount). Threshold values b1, b2, b3 for determining whether or not the vehicle is in a low μ road region, which is set with respect to a steering control angle change (slip rate change) (output amount) according to a steering (brake) alarm control amount (input amount). It is a graph which shows. (A) is a graph showing the steering control amount with respect to time, and (b) is a graph with respect to time when the normal case without correction and when the correction is made to make the control amount smaller than normal using the threshold values a1 and b1. It is a graph which shows a brake control amount. (A) is a graph showing the steering control amount with respect to time when the normal case without correction and the case where the threshold value a2 and b2 are used to correct the control amount so that the rise and fall of the control amount are more gradual than normal. ) Is a graph showing the brake control amount with respect to time. (A) is a graph showing the amount of steering control with respect to time, and (b) is the time when the correction is made to make the control start timing earlier than normal using the threshold values a3 and b3. It is a graph which shows the brake control amount with respect to.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 1, the driving support apparatus 1 according to the embodiment of the present invention is mounted on a vehicle C as an electronic control unit. The electronic control unit (driving support device) 1 includes obstacle contact possibility determination means 1a, obstacle warning means 1b, and obstacle avoidance support means 1c.
The obstacle contact possibility determination means 1a detects an obstacle based on information around the vehicle C from the radar 7, the camera 8, and the like, estimates the course of the vehicle C, and contacts the obstacle with the vehicle C. Determine and determine the level of possibility. The contact possibility level can be determined and determined in multiple stages. The level where there is no contact possibility, the level where there is a contact possibility, the level where the contact possibility is low, the level where the contact possibility is high, etc. Can be determined and determined.

  The obstacle warning means 1b issues a warning to the driver when there is a possibility of contact between the obstacle and the vehicle C. As an alarm method, the obstacle alarm means 1b transmits to the EPS (electric power steering) 2 a steering alarm control amount (input amount) ds that increases or decreases in accordance with the level of the possibility of contact. The steering wheel 3 is vibrated with an amplitude corresponding to the steering warning control amount (input amount) ds. The driver can feel the vibration from the hand holding the steering wheel 3 and know that there is a possibility that the obstacle and the vehicle C may come into contact with each other.

  As another alarm method, the obstacle alarm means 1b transmits to the brake hydraulic unit 5 a brake alarm control amount (input amount) db that increases or decreases in accordance with the level of contact possibility, and the brake hydraulic unit 5 applies a hydraulic pressure corresponding to the brake warning control amount (input amount) db to the brake 6 to brake the front wheel TF. The driver can feel this braking with his / her body and know that there is a possibility that the obstacle and the vehicle C may come into contact with each other.

  The obstacle avoidance support means 1c provides assistance for obstacle avoidance to the driver after warning by the obstacle warning means 1b when there is a possibility of contact between the obstacle and the vehicle C. Specifically, the EPS 2 and the brake hydraulic pressure are obtained so that the vehicle C obtains an appropriate route to be traveled in the future by calculation or the like, proceeds along the appropriate route (including stop), and does not easily deviate from the appropriate route. The brake 6 via the unit 5 is controlled. For this control, the obstacle avoidance support unit 1c transmits the steering control amount to the EPS 2, thereby controlling the EPS 2 and turning the front wheel TF. Further, the obstacle avoidance support unit 1c transmits a brake control amount to the brake hydraulic unit 5, thereby controlling the brake 6 to brake the front wheel TF.

  Obstacle avoidance assisting means 1c makes it difficult for the vehicle to deviate from the appropriate course so as to correct the steering control amount and the brake control amount in a scene where the friction coefficient (road surface μ) of the road surface is low and to prevent the driver from feeling uncomfortable. Can be controlled. For this control, the obstacle avoidance assisting means 1c can determine whether the friction coefficient (road surface μ) of the currently traveling road surface is low enough to be corrected. Can be distinguished.

  In order to determine whether the road surface μ is high or low, an alarm operation by the obstacle alarm means 1b is used. For example, when the alarm is a vibration of the steering wheel 3, when the obstacle alarm unit 1b inputs the steering alarm control amount (input amount) ds to the EPS 2, the EPS 2 causes the steering wheel 3 to vibrate and the front wheel TF. To steer. The turning angle of the front wheel TF changes depending on the height of the road surface μ. Since the steered angle of the front wheel TF and the steering angle of the steering wheel change in conjunction with each other and have a proportional relationship, the steering angle of the steering wheel also changes depending on the level of the road surface μ. Conversely, by measuring the steering angle of the front wheel TF and the steering angle of the steering wheel 3, the value of the road surface μ can be acquired, and the level of the road surface μ can be determined. That is, for a road surface environment (so-called black box) affected by the height of the road surface μ, the steering warning control amount ds is used as an input amount, and the steering angle of the steering wheel 3 measured and output by the steering angle sensor 4 is output. From this input amount (steering warning control amount ds) and output amount (steering angle), the level of the road surface μ is determined.

  The output amount is not limited to the steering angle of the rudder angle sensor 4, and a physical quantity representing vehicle behavior can be used. The yaw rate measured by the yaw rate sensor 9 or the lateral G measured by the lateral G sensor 10 can be used. It may be.

  Further, the alarm operation by the obstacle alarm means 1b used for determining whether the road surface μ is high or low may be braking of the front wheels TF by the brake hydraulic unit 5 and the brake 6. When the obstacle warning means 1 b inputs a brake warning control amount (input amount) db to the brake hydraulic unit 5, the brake hydraulic unit 5 brakes the front wheel TF via the brake 6. The slip ratio of the front wheel TF varies depending on the road surface μ. Conversely, by measuring the slip ratio, the value of the road surface μ can be acquired, and the level of the road surface μ can be determined. The slip ratio can be calculated from the wheel speed of the front wheel TF and the wheel speed of the rear wheel TR that is a driven wheel. The wheel speed of the front wheel TF is measured by the wheel speed sensor SF, and the wheel speed of the rear wheel TR is measured by the wheel speed sensor SR. For a road surface environment (so-called black box) that is affected by the height of the road surface μ, the brake alarm control amount db is an input amount, the slip ratio is an output amount, and this input amount (brake alarm control amount db) and output amount ( From the slip ratio), the level of the road surface μ is determined.

  The ignition switch IG is connected to the electronic control unit 1 and can be turned on and off by the driver. The electronic control unit 1 is activated when the ignition switch IG is turned on, and the electronic control unit 1 is turned on when the ignition switch IG is turned off. Stops.

  FIG. 2 shows a flowchart of a driving support method implemented in the electronic control unit (driving support device) 1. The driving support method starts when the ignition switch IG is turned on. In step S1, the driving assistance device 1 determines whether or not the ignition switch IG is turned off. When the ignition switch IG is turned off (step S1, Yes), the driving support method is stopped, and when the ignition switch IG is not turned off (step S1, No), the process proceeds to step S2.

  In step S <b> 2, the obstacle contact possibility determination unit 1 a of the driving support device 1 acquires information around the vehicle C from the radar 7 and the camera 8.

  In step S3, the obstacle contact possibility determination unit 1a detects and recognizes the obstacle based on information acquired from the radar 7 and the camera 8.

In step S4, the obstacle contact possibility determination means 1a detects and recognizes the road on which the vehicle C is traveling and the traveling direction of the vehicle C based on the information acquired from the radar 7 and the camera 8, and Estimate the course of the vehicle.

  In step S5, the obstacle contact possibility determination means 1a determines whether there is a possibility of contact between the vehicle C and the obstacle based on the detected obstacle and the estimated own vehicle course, and further determines the level of contact possibility. Judgment / determination of When it is determined that there is no possibility of contact between the vehicle C and the obstacle (step S5, none), the process returns to step S1. If it is determined that there is a possibility of contact (Yes in step S5), the process proceeds to step S6.

In step S6, the obstacle avoidance support unit 1c receives the vehicle behavior value (output amount) before the alarm control, for example, the steering angle, from the steering angle sensor 4, and stores it. As the output amount, a yaw rate, a lateral G, a slip ratio, etc. can be used in addition to the steering angle.

  In step S7, the obstacle alarm means 1b performs alarm control. When the alarm control is the steering control, the obstacle alarm means 1b transmits to the EPS 2 an alarm control signal for changing to the alarm mode and a steering alarm control amount (input amount) ds corresponding to the alarm level. To do. In EPS2, the steering wheel 3 and the front wheel TF vibrate based on the steering warning control amount (input amount) ds. When the alarm control is a brake control, the obstacle alarm means 1b sends an alarm control signal for changing to the alarm mode to the brake hydraulic unit 5 and a brake alarm control amount (input) according to the alarm level. Amount) db is transmitted. The brake hydraulic unit 5 brakes the front wheel TF by the brake 6 based on the brake alarm control amount (input amount) db. The obstacle alarm means 1b increases the steering alarm control amount (input amount) ds and the brake alarm control amount (input amount) db as the determined alarm level is higher.

  In step S <b> 8, the obstacle avoidance support unit 1 c receives a vehicle behavior value (output amount) after alarm control, for example, a steering angle, from the steering angle sensor 4.

  In step S9, the obstacle avoidance support unit 1c calculates the amount of change in the vehicle behavior value (output amount) before and after the alarm control. The amount of change in the vehicle behavior value (output amount) is calculated from the difference between the vehicle behavior value (output amount) after alarm control and the vehicle behavior value (output amount) before alarm control.

  In step S10, the obstacle avoidance support unit 1c calculates a control amount for normal obstacle avoidance support based on the alarm level, the vehicle speed (wheel speed), and the like. In the case of steering control, this control amount is a control amount for controlling obstacle avoidance assistance that is input to the EPS 2 in the same manner as the steering warning control amount (input amount) ds. If this control amount is brake control, it is a control amount that is input to the brake hydraulic unit 5 and performs obstacle avoidance support control, similarly to the brake alarm control amount (input amount) db.

  In step S11, the obstacle avoidance support unit 1c determines whether the road surface μ is high or low. If it is determined that the road surface μ is low (step S11, low), the process proceeds to step S12 to correct the control amount. If it is determined that the road surface μ is high (step S11, high), the process passes step S12. Then, the process proceeds to step S13 without correcting the control amount.

  Specifically, in determining whether the road surface μ is high or low, threshold values a1, a2, and a3 shown in FIG. 3 and threshold values b1, b2, and b3 shown in FIG. 4 are used. Threshold values a1, a2, and a3 shown in FIG. 3 are threshold values set for a vehicle behavior change (output amount) in the turning direction, for example, a yaw rate change amount or a lateral G change amount. When the (output amount) is smaller than the threshold values a1, a2, and a3, it is determined that the road surface μ is high (is a DRY road surface), and when it is greater than or equal to the threshold values a1, a2, and a3, the road surface μ is low (is a low μ road). ). The threshold values a1, a2, and a3 are set so as to increase as the steering warning control amount (input amount) ds increases (that is, as the vibration of the steering wheel 3 for warning increases). However, the present invention is not limited to this, and the threshold values a1, a2, and a3 may be constant regardless of the steering warning control amount (input amount) ds. Further, the threshold values a1, a2, and a3 are set so as to decrease as the vehicle speed increases. Further, the threshold values a1, a2, and a3 are set so as to increase as the vehicle behavior (yaw rate, lateral G, etc.) before the warning steering wheel 3 vibrations or the steering angle increases, respectively.

  Threshold values b1, b2, and b3 shown in FIG. 4 are threshold values set for (steering) steering angle change (output amount) or slip ratio change (output amount), and (steering) steering angle change (output amount) or When the slip ratio change (output amount) is smaller than the threshold values b1, b2, and b3, it is determined that the road surface μ is high (is a DRY road surface), and when the slip ratio is more than the threshold values b1, b2, and b3, the road surface μ is low (low μ). Road). The threshold values b1, b2, and b3 are larger as the steering warning control amount (input amount) ds or the brake warning control amount (input amount) db is larger (that is, as the vibration of the warning steering wheel 3 or the braking by the brake 6 is larger). , Is set to be larger. However, the present invention is not limited to this, and the threshold values b1, b2, and b3 may be constant regardless of the steering warning control amount (input amount) ds and the brake warning control amount (input amount) db. Further, the threshold values b1, b2, and b3 are set so as to decrease as the vehicle speed increases. Further, the threshold values b1, b2, and b3 are set so as to increase as the vehicle behavior (yaw rate, lateral G, etc.) before the warning steering wheel 3 vibrations or the steering angle increases, respectively.

  Using each of a plurality of (for example, six in the embodiment) thresholds a1, a2, a3, b1, b2, and b3, a plurality of times of determination of the road surface μ are made, and even one is a low μ road. When this determination is made, the process proceeds to step S12.

  In step S12, the obstacle avoidance support unit 1c corrects the control amounts of the normal obstacle avoidance support steering control and brake control calculated in step S10.

  5A and 5B show a correction method when it is determined that the road surface μ is low in the determination using the threshold values a1 and b1. That is, this correction method is applied when the amount of change in the vehicle behavior in the turning direction before and after the steering alarm is input is greater than or equal to the threshold a1, or the amount of change in the steering angle or slip ratio is greater than or equal to the threshold b1. Is the case. In this case, as shown in FIG. 5A, in the steering avoidance assist control after the steering (brake) alarm control, the (steering) control amount is changed from the normal control amount c0 to the corrected control amount c1. A correction for reducing the control amount is made. Further, as shown in FIG. 5B, in the brake avoidance support control after the steering (brake) alarm control, the (brake) control amount is changed from the normal control amount d0 to the corrected control amount d1. The correction which makes it small is made. According to these corrections, the uncomfortable feeling given to the driver can be reduced.

  FIGS. 6A and 6B show a correction method when it is determined that the road surface μ is low in the determination using the threshold values a2 and b2. That is, this correction method is applied when the amount of change in vehicle behavior in the turning direction before and after the steering alarm is input is greater than or equal to the threshold a2, or when the amount of change in steering steering angle or slip ratio is greater than or equal to the threshold b2. Is the case. In this case, as shown in FIG. 6A, in the steering avoidance assist control after the steering warning control (not shown, but after the brake warning control), the (steering) control amount control start timing A correction is made to moderate the rising change from rising to constant. Further, a correction is made to moderate the descending change from the end of control of the (steering) control amount until the trailing edge becomes zero. Further, as shown in FIG. 6B, in the brake avoidance support control after the steering warning control (not shown, but after the brake warning control), the constant rise from the control start timing of the (brake) control amount is constant. A correction has been made to moderate the rising change until. In addition, correction is made to moderate the descending change from the end of control of the (brake) control amount until the trailing edge becomes zero. According to these corrections, the uncomfortable feeling given to the driver can be reduced.

  FIGS. 7A and 7B show a correction method when it is determined that the road surface μ is low in the determination using the threshold values a3 and b3. That is, this correction method is applied when the amount of change in the vehicle behavior in the turning direction before and after the steering warning is input is greater than or equal to the threshold a3, or the amount of change in the steering angle or slip ratio is greater than or equal to the threshold b3. Is the case. In this case, as shown in FIG. 7A, in the steering avoidance assist control after the steering warning control (not shown but may be after the brake warning control), from the steering warning control end time t00, Correction is made such that the time until the control start time t11 after correction is shorter than the time until the normal control start time t01. That is, the corrected steering avoidance support control starts earlier than the normal steering avoidance support control. Further, as shown in FIG. 7B, in the brake avoidance support control after the steering warning control (not shown, but after the brake warning control), the normal control is performed from the end time t00 of the steering warning control. Correction is made so that the time until the control start time t12 after the correction is shorter than the time until the start time t02. That is, the corrected brake avoidance support control starts earlier than the normal brake avoidance support control. According to these corrections, the uncomfortable feeling given to the driver can be reduced.

  In step S13, the obstacle avoidance support unit 1c performs steering avoidance support control or brake avoidance support control. In the case of the steering avoidance support control, the obstacle avoidance support means 1c transmits to the EPS 2 an avoidance control signal for changing to the avoidance support control mode and the (steering) control amount determined in steps S10 and S12. To do. The EPS 2 steers the front wheel TF based on the steering control amount and performs obstacle avoidance support control. In the case of the brake avoidance support control, the obstacle avoidance support means 1c determines to the brake hydraulic unit 5 the avoidance control signal for changing to the avoidance support control mode, and the steps S10 and S12 (brake ) Send control amount. Based on the brake control amount, the brake hydraulic unit 5 brakes the front wheel TF via the brake 6 and performs obstacle avoidance support control.

1 Electronic control unit (driving support device)
1a Obstacle contact possibility determination means 1b Obstacle alarm means 1c Obstacle avoidance support means 2 EPS (Electric Power Steering)
3 Steering 4 Steering angle sensor 5 Brake hydraulic unit 6 Brake 7 Radar 8 Camera 9 Yaw rate sensor 10 Lateral G sensor IG Ignition switch

Claims (6)

In a driving support device that supports driving by calculating a control amount of steering control or brake control that supports avoidance of obstacles, and performing the steering control or brake control from the predetermined control start time with the control amount,
Vibrate the steering wheel,
A driving assistance apparatus, wherein the control amount or the control start time is corrected according to a change amount of a vehicle behavior or a steering angle caused by the vibration.   2. The driving support device according to claim 1, wherein when the change amount of the vehicle behavior or the steering angle is larger than a threshold value, correction is performed to reduce the control amount or to advance the control start timing.   3. The correction according to claim 1 or 2, wherein when the change amount of the vehicle behavior or the steering angle is larger than a threshold value, a correction is made to moderate a change that rises from the control start timing and rises to the control amount. The driving support device according to 1. The amplitude of the vibration increases as the possibility of contact between the vehicle and the obstacle increases.
The driving assistance apparatus according to claim 2 or 3, wherein the threshold value increases as the amplitude of the vibration increases.   The driving assistance apparatus according to any one of claims 2 to 4, wherein the threshold value decreases as the vehicle speed increases.   The driving assistance apparatus according to any one of claims 2 to 5, wherein the threshold value increases as the vehicle behavior or the steering angle before the vibration increases.

Images