JP5007167B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicle travel control device. In particular, the present invention relates to a braking control system for reducing collisions between vehicles.

  As a braking control system for reducing collisions between vehicles, means for detecting the relative relationship between the host vehicle and the preceding vehicle (distance sensor), and collision with the preceding vehicle by the driver's braking operation based on the detection signal Is disclosed that includes means for determining whether or not the vehicle can be avoided, and means for automatically applying braking when this determination cannot be avoided (Patent Document 1).

In the means for determining whether or not the collision with the preceding vehicle can be avoided by the driver's braking operation, the deceleration and the own vehicle speed assumed to be generated by the driver when the collision with the preceding vehicle is avoided. From the amount of change, the collision determination distance (braking avoidance limit distance), which is the limit distance that can avoid a collision with the preceding vehicle by braking operation, is calculated, and the distance to the preceding vehicle (measured value of the distance measurement sensor) is determined as the collision. When the distance is less than or equal to the distance, it is determined that a collision with the preceding vehicle cannot be avoided.
JP 2003-182544 A

  In such a control system, the distance measurement sensor also has a relationship with the mounting position on the vehicle, and a minimum detection distance capable of detecting the distance to the preceding vehicle is generated. The minimum detection distance means the limit distance that makes it impossible to measure correctly if the distance to the vehicle ahead is less than that, and the road surface is likely to be mistaken for the vehicle ahead, or the vehicle ahead is likely to be out of the measurement (detection) range. To do. Therefore, in the area where the collision determination distance is less than the minimum detection distance, it is not possible to determine whether or not the collision with the preceding vehicle can be avoided by the driver's operation, and the function of the system (by automatically applying the brake) It is conceivable that there is a problem that it is not possible to secure a collision with the vehicle ahead.

  The present invention has been made paying attention to such a problem, and an object thereof is to provide means for ensuring the function of the system even in a region where the collision determination distance is less than the minimum detection distance. .

  According to a first aspect of the present invention, in the vehicle travel control device, a means for measuring an inter-vehicle distance and a relative speed with a preceding vehicle, a means for setting a minimum detection distance at which the inter-vehicle distance can be measured by the measuring means, and the relative speed Based on a comparison between the collision determination distance and the minimum detection distance, a means for setting the collision determination distance as a limit distance that can avoid a collision with the vehicle ahead by the driver's operation, and whether the collision determination distance ≧ the minimum detection distance Based on the result of this determination, the instruction deceleration 1 is set when the collision determination distance is equal to or smaller than the minimum detection distance, and the instruction deceleration 1 is generated when the inter-vehicle distance is equal to or less than the collision determination distance. Means for automatically applying braking, and when the collision determination distance is not greater than the minimum detection distance based on the determination result, the command deceleration 2 corresponding to the relative speed is calculated and the inter-vehicle distance There characterized in that it comprises becomes less than the minimum detection distance and means for applying an instruction deceleration 2 automatically braked in order to generate at that time, the.

  According to a second aspect of the present invention, in the vehicle travel control apparatus according to the first aspect of the invention, the command deceleration 2 is calculated from the relative speed, the maximum deceleration that can be generated by the vehicle brake device, and the command deceleration 1. It is characterized by that.

  According to a third aspect of the present invention, in the vehicle travel control apparatus according to the first or second aspect of the present invention, the means for setting the collision determination distance is a limit distance that can avoid a collision with a preceding vehicle by braking. Means for calculating the braking avoidance limit distance from the relative speed and the maximum deceleration that the vehicle can produce by the operation of the driver, the time required for steering to avoid a collision as a limit distance that can avoid a collision with a preceding vehicle by steering, and A means for calculating a steering avoidance limit distance from the relative speed, and a means for selectively setting a smaller value of these calculated values as a collision determination distance are provided.

  According to a fourth aspect of the present invention, in the vehicle travel control apparatus according to any one of the first to third aspects of the invention, when the collision determination distance is equal to or greater than the minimum detection distance, an alarm is given to the following vehicle based on the collision determination distance. A means for setting a distance to be generated and a means for generating an alarm for the following vehicle when the distance between the preceding vehicle by the measuring means is equal to or less than a distance for generating the alarm, and a minimum when the collision determination distance is not greater than the minimum detection distance A means for setting a distance at which an alarm for the following vehicle is to be generated based on the detected distance and generating an alarm for the following vehicle when the inter-vehicle distance from the preceding vehicle by the measuring means is less than the distance at which the alarm is to be generated; It is characterized by providing.

  In the first invention, the collision determination distance is set as a limit distance that can avoid a collision with the preceding vehicle by a driver's operation from the relative speed with the preceding vehicle, and based on a comparison between the collision determination distance and the minimum detection distance. Then, it is determined whether or not the collision determination distance ≧ the minimum detection distance. When the collision determination distance is equal to or smaller than the minimum detection distance, when the distance between the vehicle and the vehicle ahead is equal to or less than the collision determination distance, braking is automatically applied, and the host vehicle decelerates with an instruction deceleration 1 (set value). When the collision determination distance is not greater than or equal to the minimum detection distance, when the inter-vehicle distance from the preceding vehicle becomes equal to or less than the minimum detection distance, braking is automatically applied, and the host vehicle decelerates with an instruction deceleration 2 (calculated value). In other words, even in a region where the collision determination distance is less than the minimum detection distance, the function of the system is ensured and the vehicle is decelerated with the command deceleration 2 by the automatically applied braking, so that the collision between the own vehicle and the preceding vehicle can be reduced. it can.

  In the second invention, when the collision determination distance is not greater than the minimum detection distance, the instruction deceleration 2 is calculated according to the relative speed with the preceding vehicle, and when the inter-vehicle distance with the preceding vehicle is equal to or less than the minimum detection distance, Braking is automatically applied to generate the commanded deceleration 2 (calculated value) at the time. For this reason, the own vehicle decelerates with an appropriate instruction deceleration 2 according to the relative speed with the preceding vehicle when the inter-vehicle distance with the preceding vehicle is equal to or less than the minimum detection distance.

  In the third invention, since the smaller one of the steering avoidance limit distance and the braking avoidance limit distance is set as the collision determination distance, the braking force is not generated prior to the driver's avoidance operation. Braking is automatically applied at an appropriate timing that does not interfere with the avoidance operation, and the collision between the host vehicle and the preceding vehicle can be reduced.

  In the fourth invention, it is possible to warn the driver of the following vehicle of the relative relationship (risk of collision) between the own vehicle and the preceding vehicle.

  An embodiment of the present invention will be described based on the drawings.

  FIG. 1 is a schematic diagram showing a configuration of a vehicle travel control apparatus, and includes a means 11 for measuring an inter-vehicle distance and a relative speed with respect to a preceding vehicle. As the means 11 for measuring the inter-vehicle distance and the relative speed with the preceding vehicle, a millimeter wave radar device is used, and the inter-vehicle distance is calculated from the time from when the millimeter wave is transmitted until the reflected wave arrives. Also, the amount of change in the inter-vehicle distance per unit time (difference between the previous measurement value and the current measurement value) is calculated as a relative speed.

  Reference numeral 10 denotes a control unit (collision damage reduction device) that controls the buzzer 16 as well as the buzzer 16 in the cab and the stop lamp 17 at the rear of the vehicle body as described later. The buzzer 16 in the driver's cab constitutes a means for warning the driver of the own vehicle of the relative relationship (approaching state) with the preceding vehicle. The stop lamp 17 at the rear of the vehicle body is also used as means for warning the driver of the following vehicle of the relative relationship (approaching state) between the host vehicle and the preceding vehicle. Note that the relative speed with respect to the preceding vehicle may be obtained from the measured value of the own vehicle speed (detected value of the vehicle speed sensor 19) and the measured value of the inter-vehicle distance.

  The control unit 10 sets a minimum detection distance (S1 in FIG. 2) that can be measured by the millimeter wave radar device 11 so that the distance between the vehicle and the preceding vehicle can be measured. Means for setting a collision determination distance as a limit distance that can avoid a collision (S2 to S4 in FIG. 2), and based on a comparison between the collision determination distance and the minimum detection distance, it is determined whether or not collision determination distance ≧ minimum detection distance Means (S5 in FIG. 2), based on the determination result, when the collision determination distance is equal to or smaller than the minimum detection distance, the instruction deceleration 1 is set, and the instruction reduction is performed when the inter-vehicle distance with the preceding vehicle is equal to or less than the collision determination distance. Means for automatically braking to generate the speed 1 (S6 to S8 in FIG. 2). When the collision determination distance is not greater than the minimum detection distance based on the determination result, the instruction deceleration 2 is calculated and the vehicle ahead When Means for inter-vehicle distance is multiplied by automatically braking to the generating instructions deceleration 2 at that time becomes less than the minimum detection distance (S9 to S11 in FIG. 2), comprising a.

  The command deceleration 1 is set to an optimum value from the experimental result. The command deceleration 2 is calculated using the relative speed with the preceding vehicle as a variable as will be described later.

  The means (S2 to S4 in FIG. 2) for setting the collision determination distance from the relative speed with the preceding vehicle is based on the relative speed with the preceding vehicle and the driver's operation as a limit distance that can avoid a collision with the preceding vehicle by braking. Means for calculating the braking avoidance limit distance from the maximum deceleration that the vehicle can emit (S2, S3 in FIG. 2), the time required for steering to avoid the collision as the limit distance by which the collision with the preceding vehicle can be avoided by steering, and the preceding vehicle From the means for calculating the steering avoidance limit distance from the relative speed (S2, S3 in FIG. 2), the means for selectively setting the smaller one of these calculated values as the collision determination distance (S4 in FIG. 2), Composed.

  FIG. 2 is a flowchart for explaining the control contents of the control unit, which is activated when the engine key is turned on. In S1, constants necessary for control are set. The time required to avoid a collision with the vehicle ahead by the driver's steering (steering operation) (steering avoidance time), the minimum detection distance at which the distance between the vehicle and the vehicle ahead can be measured (detected) by the millimeter wave radar device 11; The maximum deceleration that can be output by the vehicle by the driver's braking operation and the command deceleration 1 are set.

  In S2, the inter-vehicle distance and relative speed with the preceding vehicle measured by the millimeter wave radar device 11 are read. In S3, the steering avoidance limit distance = steering avoidance time × the relative speed with the preceding vehicle is calculated as a limit distance that can avoid a collision with the preceding vehicle by steering (steering operation). Further, the braking avoidance limit distance = (relative speed with the preceding car × relative speed with the preceding car) / (2 × maximum deceleration) is calculated as a limit distance by which a collision with the preceding car can be avoided by the braking operation. . In S4, a distance for automatically applying braking (collision determination distance) = MIN (steering avoidance limit distance, braking avoidance limit distance) is set.

  The steering avoidance limit distance will be described with reference to FIG. In FIG. 3, A is the own vehicle and B is the front vehicle. L4 is the steering avoidance limit distance. From the time (steering avoidance time) required to steer and move the vehicle as indicated by the arrow and the relative speed with the preceding vehicle, L4 = steering avoidance time × relative speed Calculated. The steering avoidance time is set to a standard value from the experimental result.

  The braking avoidance limit distance will be described with reference to FIG. In FIG. 4, A is the own vehicle, and B is a preceding vehicle (front vehicle). When the relative relationship with the preceding vehicle B is as shown in the figure, the time T required for the host vehicle A to decelerate to the same speed as the preceding vehicle B by the braking operation is from V1−α1 · T = V2. T = (V1−V2) / α1.

Travel distance L1 of the vehicle A at time T, L1 = V1 · T-α1 · T 2/2 = (V1 2 -V2 2) / (2 · α1) next, the travel distance L2 of the preceding vehicle at time T L2 = V2 · T = V2 · (V1−V2) / α1.

The limit distance L0 (braking avoidance limit distance) that can avoid a collision with the preceding vehicle B is L0 = L1−L2 = (V1 ² −V2 ² ) / (2.α1) −V2 · (V1−V2) / α1 = (V1−V2) ² / (2 · α1). If V1−V2 = Vr (relative speed) is set, L0 = Vr ² /(2.α1), and the braking avoidance limit distance L0 is calculated as (relative speed Vr × relative speed Vr) / (2 × α1). It is done. α1 is the maximum deceleration of the vehicle.

  In S5, it is determined whether or not the collision determination distance ≧ the minimum detection distance. When the determination of S5 is yes, the process proceeds to S6, while when the determination of S5 is no, the process proceeds to S9.

  In S6, the braking force corresponding to the command deceleration 1 is set. In S7, it is determined whether or not the collision determination distance is equal to or greater than the inter-vehicle distance with the preceding vehicle. If the determination in S7 is yes, the process proceeds to S8, while if the determination in S7 is no, the process returns to S2. In S8, the brake is automatically applied to generate the command deceleration 1, and the buzzer 16 in the cab and the stop lamp 17 at the rear of the vehicle body are operated.

  In S9, the braking force corresponding to the command deceleration 2 = (relative speed with the preceding vehicle × relative speed with the preceding vehicle × commanded deceleration 1) / (2 × minimum detection distance × maximum deceleration) is calculated. In S10, it is determined whether or not the minimum detection distance ≧ the inter-vehicle distance from the preceding vehicle. If the determination in S10 is yes, the process proceeds to S11. If the determination in S10 is no, the process returns to S2. In S11, the brake is automatically applied to generate the command deceleration 2, and the buzzer 16 in the cab and the stop lamp 17 at the rear of the vehicle body are operated.

  With such a configuration, the collision determination distance is set as a limit distance that can avoid a collision with the preceding vehicle by the driver's operation from the relative speed with the preceding vehicle, and based on the comparison between the collision determination distance and the minimum detection distance It is determined whether or not the collision determination distance ≧ the minimum detection distance. When the collision determination distance is equal to or smaller than the minimum detection distance, when the distance between the vehicle and the vehicle ahead is equal to or less than the collision determination distance, braking is automatically applied, and the host vehicle decelerates with an instruction deceleration 1 (set value). When the collision determination distance is not greater than or equal to the minimum detection distance, when the inter-vehicle distance with the preceding vehicle is equal to or less than the minimum detection distance, the vehicle is automatically braked and the host vehicle decelerates with the command deceleration 2 (calculated value).

  FIG. 5 is a characteristic diagram of the collision determination distance (distance where braking is automatically applied). The millimeter wave radar device 11 also has a relationship with the mounting position on the vehicle, and a minimum detection distance capable of detecting the distance to the obstacle occurs. In FIG. 5, in a region where the minimum detection distance is set and the collision determination distance is less than the minimum detection distance, the collision determination distance (thin line) is expanded to the minimum detection distance (thick line). That is, the minimum detection distance (thick line) is the collision determination distance, and it can be determined whether or not the collision with the preceding vehicle can be avoided by the driver's operation. For this reason, even in a region where the collision determination distance is less than the minimum detection distance, the function of the system is ensured, and the collision between the own vehicle and the preceding vehicle can be reduced by the automatic braking.

  In FIG. 2, when only S1 to S4 → S6 to S8 are set (there is no S5 and S9 to S11), the collision determination distance has the characteristics as shown in FIG. 7, and the region where the collision determination distance is less than the minimum detection distance. Because it is not possible to determine whether or not the collision with the vehicle ahead can be avoided by the driver's operation, the system function (reducing the collision with the vehicle ahead by automatically braking) cannot be obtained. is there.

  In S5 and S9 to S11 of FIG. 2, when the collision determination distance is not greater than the minimum detection distance, the command deceleration 2 is calculated according to the relative speed with the preceding vehicle, and the inter-vehicle distance with the preceding vehicle is less than the minimum detection distance. Then, braking is automatically applied to generate the command deceleration 2 (calculated value) at that time. For this reason, when the own vehicle has a minimum detection distance ≧ an inter-vehicle distance from the preceding vehicle, an instruction deceleration 2 corresponding to the relative speed with the preceding vehicle 2 = (relative speed with the preceding vehicle × relative speed with the preceding vehicle) X Deceleration with the indicated deceleration 1) / (2 x minimum detection distance x maximum deceleration). That is, the command deceleration 2 is adjusted according to the relative speed with the preceding vehicle, and the host vehicle can be decelerated without excess or deficiency at the minimum detection distance ≧ the inter-vehicle distance with the preceding vehicle.

  The automatic braking distance is set to the collision judgment distance = MIN (steering avoidance limit distance, braking avoidance limit distance), so that the braking force is not generated prior to the driver's avoidance operation. The brakes are automatically applied at appropriate timing, and the collision between the own vehicle and the preceding vehicle can be reduced. If the collision determination distance is set to MAX (steering avoidance limit distance, braking avoidance limit distance), there is a possibility that the automatically applied braking may interfere with the driver's avoidance operation and normal avoidance operation cannot be performed.

  Buzzer 16 in the driver's cab (means for alarming the relative relationship with the vehicle ahead of the driver of the vehicle) and stop lamp 17 at the rear of the vehicle body (relative relationship between the vehicle and the vehicle ahead of the driver of the following vehicle) The alarming means) is activated at the same time as the automatically applied braking, but may be set to operate at a timing different from the automatically applied braking. Therefore, in FIG. 2, when the collision determination distance is equal to or smaller than the minimum detection distance, a distance to generate an alarm for the own vehicle and the following vehicle is set based on the collision determination distance and the distance between the vehicle and the preceding vehicle generates the alarm. A means for generating an alarm for the host vehicle and the following vehicle when the distance is less than the target distance. When the collision determination distance is not equal to or greater than the minimum detection distance, a distance for generating an alarm for the host vehicle and the following vehicle is set based on the minimum detection distance. At the same time, it is conceivable to add means for generating an alarm for the host vehicle and the following vehicle when the distance between the vehicle and the preceding vehicle is equal to or less than the distance to generate the alarm.

FIG. 6 exemplifies the driving situation, and based on this, the control contents of the control unit 10 will be specifically described. In FIG. 6, A is the own vehicle, B is the front vehicle, and both approach at a relative speed of 20 km / h from an inter-vehicle distance of 80 m. Steering avoidance time 0.8s, the maximum deceleration 5.88m / s ² instructs deceleration 1 4.9 m / s ^2, the minimum detection distance is set 3.3 m, and.

At a point where the distance between the vehicles is 80 m (upper side in FIG. 6), the steering avoidance limit distance = steering avoidance time × relative speed = 0.8 s × 20 km / h = 4.4 m, braking avoidance limit distance = (relative speed × relative speed) / ( 2 × maximum deceleration) = (20km / h × 20km / h) / (2 × 5.88m / s 2) = 2.6m, the collision determination distance = MIN (steering avoidable limit distance, the braking avoidable limit distance) = MIN (4.4 m, 2.6 m) = 2.6 m. Collision judgment distance 2.6m <minimum detection distance 3.3m, command deceleration 2 = (relative speed x relative speed x command deceleration 1) / (2 x minimum detection distance x maximum deceleration) = (20km / h x 20km / h × 4.9 m / s ² ) / (2 × 3.3 m × 5.88 m / s ² ) = 3.90 m / s ² . Here, since the minimum detection distance is 3.3 m <the distance between the vehicles is 80 m, braking is not automatically applied.

At a distance of 3.3m between vehicles (lower side of Fig. 6), steering avoidance limit distance = steering avoidance time x relative speed = 0.8s x 20km / h = 4.4m, braking avoidance limit distance = (relative speed x relative speed) / (2 × maximum deceleration) = (20km / h × 20km / h) / (2 × 5.88m / s 2) = 2.6m, the collision determination distance = MIN (steering avoidable limit distance, the braking avoidable limit distance) = MIN (4.4m, 2.6m) = 2.6m. Collision judgment distance 2.6m <minimum detection distance 3.3m, command deceleration 2 = (relative speed x relative speed x command deceleration 1) / (2 x minimum detection distance x maximum deceleration) = (20km / h x 20km / h × 4.9 m / s ² ) / (2 × 3.3 m × 5.88 m / s ² ) = 3.90 m / s ² . Here, since the minimum detection distance is 3.3 m = the inter-vehicle distance is 3.3 m, braking is automatically applied, and the own vehicle decelerates at 3.90 m / s ² (indicated deceleration 2).

It is a schematic diagram of the control system which concerns on embodiment of this invention. It is a flowchart explaining the content of control similarly. It is explanatory drawing of a steering avoidance limit distance similarly. It is explanatory drawing of a braking avoidance limit distance similarly. It is the characteristic view of collision judgment distance similarly. It is a driving | running | working condition figure explaining a control content similarly. It is a characteristic view of another collision judgment distance.

Explanation of symbols

10 Control unit 11 Millimeter wave radar device 15 Brake device 16 Buzzer 17 Stop lamp

Claims (4)

  Means for measuring the inter-vehicle distance and relative speed with the preceding vehicle, means for setting a minimum detection distance at which the inter-vehicle distance can be measured by the measuring means, and avoiding a collision with the preceding vehicle by the driver's operation from the relative speed A means for setting a collision determination distance as a limit distance, a means for determining whether or not a collision determination distance ≧ minimum detection distance based on a comparison between the collision determination distance and the minimum detection distance, and based on the determination result When the collision determination distance is equal to or greater than the minimum detection distance, a command deceleration 1 is set, and the brake is automatically applied to generate the command deceleration 1 when the inter-vehicle distance is equal to or less than the collision determination distance. If the collision determination distance is not greater than or equal to the minimum detection distance, the instruction deceleration 2 corresponding to the relative speed is calculated, and when the inter-vehicle distance is less than the minimum detection distance, Travel control device for a vehicle, characterized in that it comprises means for applying an automatic brake to generate a rate of 2, a.   2. The vehicle travel control device according to claim 1, wherein the command deceleration 2 is calculated from the relative speed, a maximum deceleration that can be output by a vehicle brake device, and the command deceleration 1.   The means for setting the collision determination distance is a means for calculating a braking avoidance limit distance from the relative speed and the maximum deceleration that can be generated by the driver's operation as a limit distance at which a collision with a preceding vehicle can be avoided by braking. And means for calculating the steering avoidance limit distance from the relative speed and the time required for steering to avoid the collision as the limit distance that can avoid the collision with the preceding vehicle by steering, and the smaller value of these calculated values The vehicle travel control device according to claim 1, further comprising: a unit that selectively sets the determination distance.   When the collision determination distance is equal to or greater than the minimum detection distance, the distance to generate an alarm for the following vehicle is set based on the collision determination distance, and the inter-vehicle distance from the preceding vehicle by the measuring unit is equal to or less than the distance to generate the alarm. A means for generating a warning for the following vehicle and a distance for generating a warning for the following vehicle are set based on the minimum detection distance when the collision determination distance is not greater than the minimum detection distance, and the inter-vehicle distance from the preceding vehicle by the measurement means is The vehicle travel control device according to any one of claims 1 to 3, further comprising means for generating an alarm for a succeeding vehicle when the alarm is less than a distance to be generated.