JP2009096349A - Vehicle driving support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability vehicle driving support device for efficiently avoiding collision with an obstacle. <P>SOLUTION: The obstacle is detected by a camera 2 for detecting an obstacle, and a distance to the obstacle B and a lateral movement amount necessary for the collision avoidance are calculated. A steering avoidance limit and a braking avoidance limit are obtained from maximum deceleration and maximum lateral acceleration calculated based on the above values and by using a tire state sensor 3, a road surface μ sensor 4, a brake stepping amount sensor 10, a steering angle sensor 11, and a yaw rate sensor 12. Start timing of a braking assist and a steering assist is calculated based on the steering avoidance limit and the braking avoidance limit, and an automatic brake actuator 7 and a steering assist actuator 6 are efficiently combined for control. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle driving support device that assists braking and steering to avoid a collision with an obstacle ahead in the traveling direction.

With regard to the present invention, for example, the risk of a collision with an obstacle ahead of the vehicle is estimated from the vehicle speed and the yaw rate, and when it is determined that there is a risk, the adjustment of the steering gear ratio and the left and right braking force during turning A travel control device that performs control and changes the magnitude of turning according to the size of an obstacle is known (Patent Document 1).
JP 2005-254835 A

  However, since the travel control device determines the possibility of a collision with an obstacle based only on the vehicle speed and the yaw rate, the estimation accuracy is not sufficient. If the vehicle speed increases, the magnitude of the turn is changed. It is difficult to avoid a collision by itself, and it may be dangerous.

  Therefore, an object of the present invention is to obtain a highly reliable vehicle driving support device that can efficiently avoid a collision with an obstacle.

  In order to achieve the above object, in the present invention, the maximum deceleration and the maximum lateral acceleration of the vehicle are calculated to obtain the steering avoidance limit and the braking avoidance limit, and the braking assist and the braking avoidance limit are determined based on the steering avoidance limit and the braking avoidance limit. The start timing of steering assist was calculated.

  Specifically, it is a vehicle driving support device for avoiding a collision with an obstacle in front of a course, and is a control that controls a combination of a braking assist for assisting a brake operation and a steering assist for assisting a steering operation. Means, obstacle detection means for detecting the obstacle, distance calculation means for calculating the distance to the obstacle, and lateral movement amount calculation means for calculating the lateral movement amount necessary for avoiding a collision with the obstacle Vehicle performance calculation means for calculating the maximum deceleration and maximum lateral acceleration of the vehicle, and the steering avoidance limit and the braking avoidance limit from the maximum deceleration, maximum lateral acceleration, distance to the obstacle, and lateral movement amount, Timing calculating means for calculating the start timing of the braking assist and steering assist based on the steering avoidance limit and the braking avoidance limit.

  According to this configuration, first, the possibility of a collision with an obstacle including the maximum deceleration and the maximum lateral acceleration is determined, so the possibility of a collision can be determined with high accuracy. Then, the steering avoidance limit and the braking avoidance limit are obtained from these, and the brake assist and the steering assist start timing are calculated according to both limits, so that the combination control of each assist can be optimized, and the collision can be efficiently performed. Can be avoided.

  More specifically, it is preferable that the timing calculation means calculates the start timing based on the running state of the vehicle when the control for avoiding the collision with the obstacle is started.

  By doing so, the calculation processing of the steering avoidance limit, the braking avoidance limit, and the start timing is executed at an appropriate timing when the vehicle approaches the obstacle, so that stable and highly accurate collision avoidance is possible.

  The control gain of at least one of the braking assist and the steering assist is changed according to, for example, the state of the tire, the distance to the obstacle or the time until the vehicle collides with the obstacle, the road surface condition, and the driving skill of the driver. By doing so, collision can be avoided with higher accuracy.

  Also, the maximum deceleration and maximum lateral acceleration of the vehicle vary depending on various conditions during traveling.The maximum deceleration and maximum lateral acceleration can be learned and corrected based on the braking characteristics and steering characteristics during normal traveling. Therefore, the maximum deceleration and the maximum lateral acceleration that are always in accordance with the actual situation can be calculated, and the accuracy is improved.

  If the ratio between the braking assist and the steering assist is changed according to the steering avoidance limit and the braking avoidance limit, it is possible to efficiently avoid the collision and to substantially reduce the distance to the collision.

  As described above, according to the present invention, it is possible to avoid a collision with an obstacle with high accuracy and to provide a highly reliable driving support device for a vehicle.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows an example in which the vehicle driving support apparatus of the present invention is applied to an automobile (vehicle) A. As shown there, the vehicle driving support apparatus according to the present embodiment includes, for example, a vehicle speed sensor 1 that measures the vehicle speed of the automobile A and an obstacle detection camera 2 that detects an obstacle B that exists in front of the course. It is composed of a camera and an image analysis device, such as a tire condition detection sensor 3 that detects the tire condition, specifically the degree of wear on the tire surface, and a road surface μ sensor 4 that detects a sliding friction coefficient of the road surface. For example, an alarm device 5 including a head-up display (HUD) that projects an alarm display on the front windshield in front of the driver's seat, an alarm buzzer that emits an alarm sound, a steering assist actuator 6, an automatic brake actuator 7, etc. An output device; and a control unit 8 that processes various information input from the input device and controls the output device. There.

  Here, the steering assist actuator 6 is interposed between a handle S (steering wheel) and a wheel steered by the handle S, and a steering gain value (a control signal output from the control unit 8) ( The wheel steering angle is changed based on the control gain (steering assist).

  On the other hand, the automatic brake actuator 7 changes the braking strength based on a brake gain value (control gain) that is a control signal output from the control unit 8, and also automatically operates the brake for braking. Control is executed (braking assist).

  In the vehicle driving support device of this embodiment, when the vehicle A approaches the obstacle B and the control (avoidance assist) for avoiding the obstacle B is started, the steering assist actuator 6 and the automatic brake actuator 7 are appropriately set by the control unit 8. Combined and controlled.

  That is, the control unit 8 is a device that is the main component of a vehicle driving support device that is configured by an electronic member such as a CPU and a memory. In this embodiment, the control unit 8 is a known ECU (electronic control unit) 9 that controls the automobile A. It is constructed integrally. As shown in FIG. 2, the ECU 9 detects a brake pedal stroke sensor 10 that detects the brake pedal stroke, a steering angle sensor 11 that detects the steering angle of the steering wheel S, and a yaw rate of the vehicle. The ECU 9 also constitutes a part of a vehicle driving support device as an input device.

  FIG. 2 shows the configuration of the control unit 8. The control unit 8 includes a lateral movement amount calculation unit 81, an obstacle distance calculation unit 82, a brake capability database 83, a maximum deceleration calculation unit 84, Maximum deceleration correction amount calculation unit 85, maximum lateral acceleration calculation unit 86, maximum lateral acceleration correction amount calculation unit 87, braking avoidance limit calculation unit 88, steering avoidance limit calculation unit 89, start timing calculation unit 90, steering gain calculation unit 91 Various programs such as a brake gain calculation unit 92 and a database are installed.

  Based on the image information input from the obstacle detection camera 2, the lateral movement amount calculation unit 81 moves the host vehicle A in the lateral direction perpendicular to the traveling direction when the obstacle B is dodged by a handle operation. Then, a lateral movement amount (necessary lateral movement amount) for avoiding the front obstacle B is calculated, and the result is output to the steering avoidance limit calculation unit 89.

  The obstacle distance calculation unit 82 calculates the distance from the host vehicle A to the obstacle B ahead based on the image information input from the obstacle detection camera 2, and the distance is within a predetermined range. It is determined whether or not there is, and the results are output to the start timing calculation unit 90.

  The brake capacity database 83 stores map data representing the brake capacity of the brake system mounted on the automobile A, and outputs the map data to the maximum deceleration calculation unit 84.

  The maximum deceleration calculation unit 84 calculates the maximum deceleration that the vehicle A can currently exhibit using the map data, the tire condition, the sliding friction coefficient of the road surface, and the like, and the result is sent to the braking avoidance limit calculation unit 88. Output.

  The maximum deceleration correction amount calculation unit 85 supplements the learning function of the maximum deceleration calculation unit 84, and when the automobile A is driving normally, the brake depression amount and the vehicle speed relative to the depression amount Are periodically compared, and if there is a change in the relationship between the two, the maximum deceleration correction amount is calculated from the change and output to the maximum deceleration calculation unit 84, and always the maximum according to the actual situation It is configured so that the deceleration can be calculated.

  The maximum lateral acceleration calculation unit 86 stores map data representing the maximum lateral acceleration of the car A, and presents the car A currently using the map data, the vehicle speed, the tire condition, the sliding friction coefficient of the road surface, and the like. The maximum lateral acceleration to be obtained is calculated, and the result is output to the steering avoidance limit calculation unit 89.

  The maximum lateral acceleration correction amount calculation unit 87 complements the learning function of the maximum lateral acceleration calculation unit 86, and when the automobile A is driving normally, the steering angle and the rotational angular velocity with respect to the steering angle are periodically set. If there is a change in the relationship between the two, the correction amount of the maximum lateral acceleration is calculated from the change and output to the maximum lateral acceleration calculation unit 86, and the maximum lateral acceleration according to the actual situation is always calculated. It is configured to be able to.

  The braking avoidance limit calculation unit 88 calculates a minimum distance (braking avoidance limit) from the own vehicle A to the obstacle B, which is necessary until the brake is activated and the vehicle A stops, from the maximum deceleration and the vehicle speed. The result is output to the start timing calculation unit 90.

  The steering avoidance limit calculation unit 89 determines the minimum distance from the own vehicle A to the obstacle B (steering avoidance limit) required to move the required lateral movement amount from the maximum lateral acceleration, the vehicle speed, and the necessary lateral movement amount. And the result is output to the start timing calculation unit 90.

  Although the details will be described later, the start timing calculation unit 90 determines the vehicle speed, the braking avoidance limit, and the steering avoidance limit so that optimal control can be executed when the vehicle A approaches the obstacle B and starts avoidance assist. The start timing of braking assist and steering assist is calculated, and output to the alarm device 5, the steering gain calculating unit 91, and the brake gain calculating unit 92 based on the results.

  The steering gain calculation unit 91 calculates a steering gain value based on the output from the start timing calculation unit 90, and outputs the calculated steering gain value to the steering assist actuator 6. On the other hand, the brake gain calculation unit 92 calculates a brake gain value based on the output from the start timing calculation unit 90, and outputs the calculated brake gain value to the automatic brake actuator 7.

  In the present embodiment, the steering gain calculation unit 91 and the brake gain calculation unit 92 mainly constitute control means, the obstacle detection camera 2 constitutes obstacle detection means, and the distance between obstacles in this embodiment. The calculation unit 82 constitutes a distance calculation unit, the lateral movement amount calculation unit 81 constitutes a lateral movement amount calculation unit, a brake capability database 83, a maximum deceleration calculation unit 84, a maximum deceleration correction amount calculation unit 85, a maximum lateral displacement The acceleration calculation unit 86 and the maximum lateral acceleration correction amount calculation unit 87 constitute a vehicle performance calculation unit, and the braking avoidance limit calculation unit 88, the steering avoidance limit calculation unit 89, and the start timing calculation unit 90 constitute a timing calculation unit. .

  Next, the flow of control by the vehicle driving support apparatus having the above configuration will be described with reference to the flowchart of FIG.

  First, when the automobile A starts running and this apparatus operates, various data are input to the control unit 8 from each input device such as the vehicle speed sensor 1 and the obstacle detection camera 2 (step S1). ).

  Then, during normal driving, whether or not learning correction can be performed is periodically determined (step S2). When learning correction is performed, the maximum deceleration correction amount calculation unit 85 of the control unit 8 and the maximum The lateral acceleration correction amount calculation unit 87 performs a process of calculating the maximum deceleration and the maximum lateral acceleration correction amounts (steps S3a and S3b).

  For example, FIG. 4 is a conceptual diagram of the maximum deceleration correction amount calculation process, and detects a change in braking capacity from the relationship between the brake stepping amount and deceleration during normal driving indicated by a black circle in the figure. The maximum deceleration correction amount indicated by the white circle is calculated from the degree of the change.

  When the vehicle A approaches the obstacle B ahead and the distance calculation unit 82 determines that the distance to the obstacle B is within a predetermined range (step S4), a series of avoidance assists. Is started (step S5).

  When the avoidance assist is started, first, the alarm device 5 is actuated by an instruction from the start timing calculation unit 90, and the driver is warned that the vehicle is approaching the obstacle B by HUD or an alarm buzzer (step). S6).

  On the other hand, in the control unit 8, the maximum deceleration calculation unit 84 calculates the current maximum deceleration (step S7). That is, the maximum deceleration is calculated based on the braking ability when starting avoidance assist control (hereinafter referred to as control start), the tire condition, the sliding friction coefficient of the road surface, and the correction amount.

  Subsequently, the braking avoidance limit calculation unit 88 calculates the braking avoidance limit based on the maximum deceleration and the vehicle speed at the start of control (step S8).

  Further, the necessary lateral movement amount is calculated by the lateral movement amount calculating unit 81 (step S9), and the steering avoidance limit calculating unit 89 is based on the necessary lateral movement amount and the maximum lateral acceleration, vehicle speed, and correction amount at the start of control. A steering avoidance limit is calculated (step S10).

  Note that the processing for calculating the braking avoidance limit (steps S7 and S8) and the processing for calculating the steering avoidance limit (steps S9 and S10) may be in reverse order or in parallel.

  Based on the braking avoidance limit and the steering avoidance limit obtained in this way, and the vehicle speed at the start of control, the start timing calculation unit 90 determines a plurality of start points that serve as starting points (start timings) for the control of the brake assist and the steering assist. Calculation is performed (step S11), and an avoidance control process in which braking assist and steering assist are efficiently combined is executed according to the start point (step S12).

  This avoidance control process will be described in detail with reference to FIGS.

  FIG. 5 illustrates the contents of the avoidance control process for each vehicle speed. On the other hand, FIG. 6 illustrates the relationship between each process in FIG. 5 and the braking avoidance limit and the steering avoidance limit. The horizontal axis indicates the vehicle speed, and the vertical axis indicates the distance from the vehicle A to the obstacle B. Is shown. FIG. 7 shows changes with time in each control gain of braking assist and steering assist. In FIG. 7, the solid line is the steering gain value, and the broken line is the brake gain value.

  As shown in FIG. 6, the braking avoidance limit and the steering avoidance limit cross each other, and the steering avoidance limit is larger than the braking avoidance limit in the range of the vehicle speed (Va) lower than the intersection. In the range of the vehicle speed (Vb) higher than the intersection, the braking avoidance limit is larger than the steering avoidance limit. 5 and 7A show the former, FIG. 5B shows the latter, and FIG. 6 shows the processing corresponding to this by a broken line. The white circles in the figure are the starting points, and LA1 and the like are the symbols.

  As shown in FIG. 5A, when the vehicle speed is relatively low, when the vehicle A approaches the obstacle B and avoidance assist is started (LA1), the following control is performed following the previous series of processing. Processing is executed.

  That is, the steering assist is started first, and the steering gain value is controlled to gradually increase as shown in FIG. In addition, a braking assist is also started after the steering assist, and a weak braking force is forcibly applied to the automobile A in the present embodiment.

  Then, the steering angle of the wheel with respect to the steering wheel operation gradually increases due to the steering assist, and the automobile A turns more rapidly. During this time, as indicated by an imaginary line T1 in FIG. The obstacle B can be avoided by the operation. Note that the amount of change in the steering gain value is not necessarily a constant value, and can be changed according to the state of the tire, the state of the road surface, and the skill of the driver, as will be described in detail later.

  When the vehicle A gets closer to the obstacle B and exceeds the steering avoidance limit (LA2), the steering gain value is controlled to gradually decrease as shown in FIG. It is controlled to gradually increase. During this time, the obstacle B can no longer be avoided only by operating the steering wheel, but as shown by the imaginary line T2 in FIG. 5A, the obstacle B can be stopped before the obstacle B by a combination with the brake operation. it can.

  When the braking avoidance limit is exceeded (LA3), collision avoidance cannot be performed, so that the steering assist is terminated, the steering gain value is returned to the initial state, and sudden braking is performed.

  Finally, the crash brake is activated so that the driver cannot steer even if the steering wheel is operated to generate the maximum deceleration, thereby reducing the vehicle speed at the time of the collision as much as possible.

  On the other hand, when the vehicle speed is relatively high as shown in FIG. 5B, when the avoidance assist is started (LB1), the steering assist is started in the same manner as in FIG. As shown in 7 (b), the steering gain value is controlled to gradually increase. However, the amount of change is smaller than that in (a) because the vehicle speed is high. In addition, a braking assist is also started after the steering assist, and a weak braking force is forcibly applied to the automobile A in the present embodiment.

  When the vehicle speed is high, the braking avoidance limit is reached first. Therefore, when this limit is exceeded (LB2), the steering gain is further increased, that is, the amount of change is changed. By doing so, the obstacle B can be avoided and avoided by the driver's steering operation as shown by an imaginary line S1 in FIG. 5B before the steering avoidance limit.

  When the steering avoidance limit is exceeded (LB3), for example, the cooperative control of the braking assist and the steering assist is performed such that the steering gain value is gradually decreased and the brake gain value is gradually increased. During this time, for example, as shown by an imaginary line S2 in FIG. 5B, the obstacle B can be avoided by avoiding the driver's steering operation.

  Then, when the avoidance limit by the brake steering cooperative control is exceeded (LB4), the collision avoidance cannot be performed. Therefore, the steering assist is finished, the steering gain value is returned to the initial state, and sudden braking is performed.

  Finally, the crash brake is actuated so that the driver cannot steer even if the steering wheel is operated to generate the maximum deceleration, thereby reducing the vehicle speed at the time of collision as much as possible (LB5).

  The steering gain value (control gain) up to the steering avoidance limit in the above-mentioned steering assist control is used in the steering assist control so that the accuracy of the steering assist control can be improved and the collision with the obstacle B can be avoided more reliably. It can be changed according to each influencing factor.

  For example, FIG. 8 illustrates the setting of the steering gain value for each factor, and FIG. 8A illustrates the steering gain values from LA1 to LA2 in the above-described embodiment serving as the reference. The steering gain value continuously increases as the distance to the object B decreases.

  (B) shows a case where the steering gain value is shifted and changed by a predetermined amount in accordance with the state of the road surface, that is, the change of the sliding friction coefficient detected by the road surface μ sensor 4. For example, when the road surface is wet, it is more slippery than when it is dry, so slipping or spinning is less likely to occur by reducing the steering gain value.

  (C) is a case where the steering gain value is shifted and changed by a predetermined amount in accordance with the tire state, that is, the degree of wear on the tire surface detected by the tire state detection sensor 3. For example, when the degree of wear on the tire surface is large and slippery, the steering gain value may be reduced.

  (D) is a case where the steering gain value is shifted and changed by a predetermined amount according to the driving skill of the driver. For example, if the driver's driving skill is inferior, the steering wheel S can be easily turned more than necessary, and thus the influence can be reduced by reducing the steering gain value. The driver's driving skill is monitored by comparing the driving state in a normal driving state using, for example, the vehicle speed sensor 1, the steering angle sensor 1, the yaw rate sensor 12, and the like, and compared with predetermined driving skill data set in advance. do it.

  As described above, according to the vehicle driving support device of the present invention, the steering avoidance limit and the braking avoidance limit are obtained from the maximum deceleration and the maximum lateral acceleration calculated based on the current data, and braking is performed based on these. Since each start timing and ratio of assist and steering assist, control gain, and the like are set efficiently, collision with an obstacle can be avoided with high accuracy, and the driver can drive more safely.

  Note that the vehicle driving support apparatus according to the present invention is not limited to the above-described embodiment, and includes various other configurations. That is, in the above embodiment, the content of the avoidance assist is set based on the distance between the car A and the obstacle B, but is set based on the time until the car A collides with the obstacle B. You can also. Not only the steering gain value but also the brake gain value may be automatically changed according to each factor affecting the braking assist.

It is a conceptual diagram which shows the vehicle to which the driving assistance device for vehicles of this invention is applied. It is a block diagram which shows the structure of the driving assistance device for vehicles of this invention. It is a flowchart which shows the flow of a process. It is a conceptual diagram for demonstrating the correction process of the maximum deceleration. It is a conceptual diagram for demonstrating the content of avoidance assistance. (A) shows a case where the vehicle speed is relatively low, and (b) shows a case where the vehicle speed is relatively high. It is a figure for demonstrating the relationship between each process in FIG. 5, a braking avoidance limit, and a steering avoidance limit. It is a figure for demonstrating the change of a control gain. (A) shows a case where the vehicle speed is relatively low, and (b) shows a case where the vehicle speed is relatively high. It is a figure for demonstrating the setting of a control gain.

Explanation of symbols

A car (vehicle)
B Obstacle 1 Vehicle speed sensor 2 Obstacle detection camera 3 Tire condition detection sensor 4 Road surface μ sensor 5 Alarm device 6 Steering assist actuator 7 Automatic brake actuator 8 Control unit 9 ECU
DESCRIPTION OF SYMBOLS 10 Brake tread sensor 11 Rudder angle sensor 12 Yaw rate sensor 81 Lateral movement amount calculation part 82 Obstacle distance calculation part 83 Brake capability database 84 Maximum deceleration calculation part 85 Maximum deceleration correction amount calculation part 86 Maximum lateral acceleration calculation part 87 Maximum lateral acceleration correction amount calculation unit 88 Brake avoidance limit calculation unit 89 Steering avoidance limit calculation unit 90 Start timing calculation unit 91 Steering gain calculation unit 92 Brake gain calculation unit

Claims (8)

A vehicle driving support device for avoiding a collision with an obstacle in front of a course,
Control means for controlling braking assist and steering assist in combination;
Obstacle detection means for detecting the obstacle;
Distance calculating means for calculating the distance to the obstacle;
Lateral movement amount calculating means for calculating a lateral movement amount necessary for avoiding a collision with the obstacle,
Vehicle performance calculating means for calculating the maximum deceleration and the maximum lateral acceleration of the vehicle;
The steering avoidance limit and the braking avoidance limit are obtained from the maximum deceleration, the maximum lateral acceleration, the distance to the obstacle, and the lateral movement amount, and the start timing of the braking assist and the steering assist based on the steering avoidance limit and the braking avoidance limit. And a timing calculation means for calculating the vehicle driving support device. The vehicle driving support device according to claim 1,
The vehicle driving support device according to claim 1, wherein the timing calculation means calculates a start timing based on a running state of the vehicle when control for avoiding a collision with an obstacle is started. In the vehicle driving assistance device according to claim 1 or 2,
At least one control gain of the braking assist and the steering assist is changed according to a tire state. In the vehicle driving assistance device according to any one of claims 1 to 3,
At least one control gain of the braking assist and the steering assist is changed according to a distance to the obstacle or a time until the vehicle collides with the obstacle. In the vehicle driving assistance device according to any one of claims 1 to 4,
At least one control gain of the braking assist and the steering assist is changed according to a road surface state. In the vehicle driving support device according to any one of claims 1 to 5,
At least one control gain of the braking assist and the steering assist is changed according to the driving skill of the driver. In the vehicle driving assistance device according to any one of claims 1 to 6,
A vehicle driving support apparatus, wherein the maximum deceleration and the maximum lateral acceleration of the vehicle are learned and corrected based on brake characteristics and steering characteristics during normal traveling. In the vehicle driving assistance device according to any one of claims 1 to 7,
A vehicle driving assistance device, wherein a ratio between the braking assist and the steering assist is changed according to a steering avoidance limit and a braking avoidance limit.

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