Search

EP-4446180-B1 - PRELIMINARY BRAKING DEVICE AND PRELIMINARY BRAKING METHOD

EP4446180B1EP 4446180 B1EP4446180 B1EP 4446180B1EP-4446180-B1

Inventors

  • AOSHIMA, Hidemichi

Dates

Publication Date
20260506
Application Date
20240205

Claims (11)

  1. A preliminary braking device (10) comprising: a following vehicle detection unit (12) configured to detect vehicle speed of a following vehicle (300) following a vehicle (100) and an inter-vehicle distance (D) to the following vehicle (300); a deceleration area detection unit (14) configured to detect a deceleration area (30) provided for deceleration of the vehicle (100) in a traveling lane (31) ahead of the vehicle (100); and a braking activation unit (17) configured to, when the inter-vehicle distance (D) to the following vehicle (300) is smaller than a predetermined value when the vehicle (100) passes through a position before the deceleration area (30) by a predetermined distance, cause a brake system (21) to activate preliminary braking for generating deceleration smaller than or equal to a predetermined value.
  2. The preliminary braking device (10) according to claim 1, wherein the predetermined value of the inter-vehicle distance (D) is defined by a time-to-collision (TTC).
  3. The preliminary braking device (10) according to claim 1, wherein the predetermined value of the inter-vehicle distance (D) is defined by a physical distance between the vehicle (100) and the following vehicle (300).
  4. The preliminary braking device (10) according to claim 1, further comprising a deceleration possibility determination unit (16) configured to estimate a possibility that the brake system (21) is operated by a driver of the vehicle (10) in the deceleration area (30), wherein when the possibility is higher than or equal to a predetermined value, the braking activation unit (17) causes the brake system (21) to activate the preliminary braking.
  5. The preliminary braking device (10) according to claim 4, wherein the deceleration possibility determination unit (16) is configured to determine that the deceleration possibility of the vehicle (100) is higher than or equal to the predetermined value in at least one of an event in which a preceding vehicle (200) ahead of the vehicle (100) is decelerated within the predetermined distance from the vehicle (100), an event in which a traffic signal (33) installed on the traveling lane (31) of the vehicle (100) in the deceleration area (30) indicates vehicle's traveling prohibition, an event of estimating switching of the traffic signal (33), an event in which a traffic signal for pedestrians (34) in a crosswalk (30b) laid on the traveling lane (31) in the deceleration area (30) indicates pedestrian's crossing caution, and an event in which a direction indicator (23) is operated in the vehicle (100).
  6. The preliminary braking device (10) according to claim 1, wherein, upon determining that the following vehicle (300) is accelerated, the braking activation unit (17) is configured to activate the preliminary braking at an earlier timing than a timing to be determined when the following vehicle (300) travels at constant speed.
  7. The preliminary braking device (10) according to claim 1, wherein upon determining that the following vehicle (300) is accelerated, the braking activation unit (17) is configured to moderate a deceleration gradient in the preliminary braking in comparison with a deceleration gradient to be determined when the following vehicle (300) travels at constant speed.
  8. The preliminary braking device (10) according to claim 1, wherein upon determining that the following vehicle (300) is decelerated, the preliminary braking unit (17) is configured to activate the preliminary braking at a later timing than a timing to be determined when the following vehicle (300) travels at constant speed.
  9. The preliminary braking device (10) according to claim 1, wherein upon determining a high acceleration frequency of the following vehicle (300), the braking activation unit (17) is configured to activate the preliminary braking at an earlier timing than a timing to be determined when the following vehicle (300) travels at constant speed.
  10. The preliminary braking device (10) according to claim 1, wherein upon determining a high relative speed of the following vehicle (300) to the vehicle (100), the braking activation unit (17) is configured to activate the preliminary braking at an earlier timing than a timing to be determined when the vehicle (100) and the following vehicle (300) travel at equal speed.
  11. A preliminary braking method comprising: detecting vehicle speed of a following vehicle (300) following a vehicle (100) and an inter-vehicle distance (D) to the following vehicle (300); detecting a deceleration area (30) provided for deceleration of the vehicle (100) in a traveling lane (31) ahead of the vehicle (100); and when the inter-vehicle distance (D) to the following vehicle (300) is smaller than a predetermined value when the vehicle (100) passes through a first position before the deceleration area (30) by a first distance, causing a brake system (21) to activate preliminary braking for generating deceleration smaller than or equal to a predetermined value at a second position before the deceleration area by a second distance smaller than the first distance.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a preliminary braking technique for a vehicle traveling in a deceleration area such as an area before an intersection installed on a road. Description of the Related Art According to the Road Traffic Act in Japan, a driver of a vehicle approaching an intersection at a crossroad or a T junction is required to reduce the speed of the vehicle, except for a predetermined case in which the vehicle travels on a priority road. In recent years, a technique for preventing or reducing the rear-end collision by a following vehicle immediately before an intersection on a road has been developed. For example, Japanese Patent Application Publication No. 2018-203252 discloses a technique relating to the operation at an intersection among three vehicles for performing adaptive cruise control in tandem in which a host vehicle is traveling between other two vehicles. To prepare for collision, the technique is designed to pressurize the brake line by a minimum amount of brake pressure necessary to place brake pads on brake disks, in place of a reduction in the inter-vehicle distance to a front vehicle at the intersection. As a result, when a driver of the host vehicle applies the brake, the brake line can react quickly to prevent the host vehicle from colliding with the front vehicle. In the above-described technique, however, when the inter-vehicle distance to a rear vehicle following the host vehicle is short, the rear vehicle may collide with the host vehicle. This is because the host vehicle has high responsiveness in the brake line, which may cause a fear that slightly braking the host vehicle may lead to sudden braking. Therefore, it is desirable to provide a control method enabling a vehicle to safely enter a deceleration area at an intersection on a road. Another example of prior art describing a vehicle braking based on external object communications can be found in US 2014/067220 A1. SUMMARY OF THE INVENTION The present invention is made in consideration of such circumstances and aims to provide a preliminary braking device and a preliminary braking method for performing preliminary braking under a predetermined condition to enable a vehicle to safely enter a deceleration area on a road. A preliminary braking device according to the present embodiment is defined in claim 1. A preliminary braking method according to the present embodiment is defined in claim 11. EFFECT OF THE INVENTION According to the present invention, preliminary braking is performed under the predetermined condition to enable the vehicle to safely enter a deceleration area on a road. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the configuration of a vehicle equipped with a preliminary braking device according to the embodiment of the present invention.Fig. 2 is a schematic view showing a deceleration area on a road to which the vehicle is going to enter.Fig. 3 is a flowchart showing the operation of the preliminary braking device according to the embodiment of the present invention. DETAILED DESCRIPTION A preliminary braking device and a preliminary braking method according to the present invention will be described in detail below with reference to the accompanying drawings. In the following description, "front side" and "rear side" are defined in a direction viewed from a driver sitting on a driver seat of a vehicle. Fig. 1 is a block diagram showing the configuration of a vehicle 100 equipped with a preliminary braking device 10 according to the embodiment of the present invention. In Fig. 1, in the configuration of the vehicle 100, some configuration having low relevancy with the preliminary braking device 10 such as an engine is omitted in illustration. As shown in Fig. 1, the preliminary braking device 10 according to the present embodiment includes a surrounding situation detection unit 11 and a braking activation unit 17 (e.g., a brake ECU 18). The function of the braking activation unit 17 is exerted as the function of the brake ECU (Electronic Control Unit) 18 for electronically controlling, for example, a brake system 21 (e.g., a brake pedal 21a). As shown in Fig. 1, the preliminary braking device 10 is connected to peripheral devices such as the brake system 21, a display unit 22, a blinker (or a direction indicator) 23, and a wheel speed sensor 24 through an in-vehicle network 25 in an information-exchangeable manner. The in-vehicle network 25 is configured by, for example, a bus of CAN-FD (i.e., a controller area network with flexible data rate). In the following, the configurations 11 and 17 of the preliminary braking device 10, and the relationship between the configurations 11, 17 and the peripheral devices 21-24 connected to the preliminary braking device 10 will be described in detail. The surrounding situation detection unit 11 is configured to acquire the arrangement information of objects and markings outside the vehic