JP4842347B2 - Inter-vehicle distance control device - Google Patents

Description

  The present invention relates to an inter-vehicle distance control device that performs follow-up traveling control while maintaining an inter-vehicle distance with respect to a preceding vehicle.

  2. Description of the Related Art In recent years, in vehicles such as automobiles, techniques for recognizing the external environment of the own vehicle using a laser radar or the like and ensuring safety, running control, and the like have been developed. In particular, with regard to running control, an automatic cruise control (ACC) system that automatically controls the speed of the vehicle and the distance from the preceding vehicle based on road conditions recognized by laser radar, etc. is a typical technology. It has been put into practical use.

  In such an ACC control system, the preceding vehicle may not be supplemented (lost) for some reason. In order to deal with such a situation, for example, Patent Document 1 discloses a technique for controlling the host vehicle by holding the immediately preceding acceleration / deceleration target value within a predetermined time when the preceding vehicle is not detected during follow-up traveling. Is disclosed.

  Patent Document 2 discloses a technique for optimizing lost determination by changing the time from when it becomes impossible to detect the preceding vehicle until it is determined to be lost depending on the cause of the loss of the preceding vehicle. .

JP-A-6-320983 JP 2007-69728 A

  However, in the technique disclosed in Patent Document 1, when the preceding vehicle is lost, the previous acceleration / deceleration target value is maintained and the vehicle is controlled so that the brake control can be performed even if the preceding vehicle changes from deceleration to acceleration. There is a possibility of continuing, and there is a possibility that the driver feels uncomfortable.

  Further, in the technique disclosed in Patent Document 2, the current inter-vehicle distance is complemented based on the inter-vehicle distance and the relative speed when the preceding vehicle can no longer be captured until it is determined that the preceding vehicle is lost and the follow-up running control is canceled. The estimation is performed, and the control is continued by using the estimated data. For this reason, even in a situation where the preceding vehicle really disappears, the control based on the estimated data is performed, and similarly, there is a possibility that the driver feels uncomfortable.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an inter-vehicle distance control device that can perform appropriate control with little discomfort for a driver even when a preceding vehicle is lost.

In order to achieve the above object, an inter-vehicle distance control apparatus according to the present invention is an inter-vehicle distance control apparatus that captures a preceding vehicle ahead of the host vehicle and performs follow-up running control while maintaining the inter-vehicle distance with respect to the preceding vehicle. In a low-speed traveling area where the vehicle speed and the vehicle speed of the own vehicle are each less than or equal to a predetermined value, a lost determination unit that determines that the preceding vehicle has been lost, and the deceleration of the own vehicle is equal to or greater than a threshold value and the brake continues for a set time or more. A nose dive determination unit for determining that the vehicle has made a nose dive when the vehicle speed of the host vehicle is equal to or lower than the vehicle speed when the lost of the preceding vehicle is determined, and a lost determination result by the lost determination unit, and from the nose dive determination result by the nose dive determination unit, determines whether to continue the following cruise control to the preceding vehicle, be determined to have lost the preceding vehicle, the vehicle is not nose dive The Most When it is determined, while releasing the following distance control to the preceding vehicle, is determined to be lost the preceding vehicle and the host vehicle is in when it is determined that the nose dive, the travel control of the vehicle Based on the control continuation determination unit for instructing continuation and the control continuation instruction from the control continuation determination unit, the distance and vehicle speed of the preceding vehicle are estimated from the values immediately before the lost vehicle, and the traveling control of the host vehicle is continued based on the estimated values. And a control continuation unit.

  According to the present invention, it is possible to perform appropriate control with less discomfort even when the preceding vehicle is lost.

Overall configuration diagram of cruise control system Functional block diagram for lost processing during deceleration Flow chart of lost processing during deceleration

Embodiments of the present invention will be described below with reference to the drawings.
The inter-vehicle distance control device in the present embodiment is configured as a cruise control system using a laser radar as a detection device for an object existing outside the host vehicle such as a preceding vehicle, and follows in accordance with the result of capturing the preceding vehicle by the laser radar. Various functions related to ACC control (Adaptive Cruise Control) that automatically switches between running and constant speed running are realized. Specifically, as shown in FIG. 1, the cruise control system 1 according to the present embodiment includes a plurality of control units connected via a network by a CAN (Controller Area Network) communication bus 100.

  The unit that is the center of the system is an ACC control unit 10 that is integrally provided with a laser radar 10a, and is attached to, for example, a front bumper structure material of the host vehicle. The laser light emitted from the laser radar 10a is two-dimensionally scanned in a predetermined range in the horizontal direction and the vertical direction, and is based on the time difference between the transmitted wave and the received wave reflected and received by an external target. Distance information for each of the points inside is acquired. From this distance information, the distance between the preceding vehicle and the host vehicle, the vehicle speed (relative vehicle speed) of the preceding vehicle, and the like are calculated.

  Other control units that form the cruise control system 1 include a brake control unit 20 for brake control, an EPB control unit 30 for controlling the activation / release of an EPB (Electrical Parking Brake), and display control for various displays. There are a meter control unit 40, a body control unit 50 for body system control such as a power window, a seat belt, and a door, a transmission control unit 60 for transmission control, and an engine control unit 70 for engine control. The ACCC control unit 10 is connected to the network.

  In addition, a relay coil of a brake lamp relay 3 is connected to the ACC control unit 10 in order to turn on the brake lamp 2 when an automatic brake is activated during ACC control. The brake lamp relay 3 has a brake terminal 2 connected to its common terminal, a normally closed contact terminal connected to the battery power source (+ B) 5 via the brake lamp switch 4, and a normally open contact terminal connected to the battery power source 5. It is connected. The brake lamp switch 4 is a switch that is connected to a brake pedal (not shown) and whose contact is closed when the brake pedal is depressed.

  That is, in the ACC non-operating state, when the driver depresses the brake pedal, the brake lamp switch 4 is turned ON, and a voltage is applied from the battery power source 5 to the brake lamp 2 via the normally closed contact of the brake lamp relay 3. 2 lights up. On the other hand, during the ACC operation, even if the brake lamp switch 4 remains off, the lighting / non-lighting of the brake lamp 2 is controlled by the ACC control unit 10, and the normally open contact of the brake lamp relay 3 is closed during the automatic braking operation. Thus, a voltage is applied from the battery power source 5 to the brake lamp 2, and the brake lamp 2 is lit.

  In addition to the brake lamp switch 4, a brake lamp switch 6 that opens a contact point when the brake pedal is depressed is connected to the brake pedal. The brake lamp switch 6 has one terminal connected to an ignition (IGN) switch 7 and the other terminal connected to the input side of the engine control unit 70.

  The vehicle speed and the inter-vehicle distance in the cruise control are set by the user manually operating the command switch 80 connected to the engine control unit 70. The command switch 80 is an operation switch including a push switch and a toggle switch arranged on the steering wheel, and is a cruise switch (indicated as “CRUISE” in FIG. 1) 80a that is a main switch for turning on / off the operation of the ACC control system. A cancel switch for canceling the ACC control (displayed as “CANCEL” in FIG. 1) 80b, a set / coast switch (in FIG. 1) for setting the ACC or changing the vehicle speed at the constant speed to the lower side. "SET /-" is displayed) 80c, an inter-vehicle distance setting switch 80d for setting the inter-vehicle distance between the preceding vehicle and the host vehicle, resetting at the set vehicle speed memorized last time, or changing the set vehicle speed Vset to the increasing side Resume / Accelerate switch (displayed as “RES / +” in FIG. 1) 80e

  When the cruise switch 80a is turned on, the switch-on information is transmitted from the engine control unit 70 to the other control unit via the CAN communication bus 100, and the system is activated. At this time, the meter control unit 40 turns on the “CRUISE” indication on the display provided in the instrument panel and presents the state of the ACC control system to the driver.

  The display indicating the status of the ACC control system includes “CRUISE”, “READY” indicating a standby state for ACC control, and “SET” indicating that the vehicle speed is set via the command switch 80. ", A graphic display showing the capture state of the preceding vehicle and the set inter-vehicle distance, a numerical display of the set vehicle speed, and the like.

  The ACC control unit 10 and each control unit 20, 30, 40, 50, 70 transmit / receive information via the CAN communication bus 100, and mainly control the throttle control and transmission control unit 60 via the engine control unit 70. The vehicle speed and the inter-vehicle distance set by the driver are maintained by shift control via the brake and brake control via the brake control unit 20.

  That is, the ACC control unit 10 performs constant speed traveling at the set vehicle speed set by the driver and follow-up traveling to the preceding vehicle with the set vehicle speed as the upper limit in accordance with the presence or absence of the preceding vehicle detected by the laser radar 10a. Switch automatically. In the follow-up traveling to the preceding vehicle, the target vehicle speed in the ACC control is calculated based on the inter-vehicle distance between the host vehicle and the preceding vehicle, the relative speed, and the acceleration of the preceding vehicle, and the target vehicle speed is transmitted to the engine control unit 70. . The engine control unit 70 executes throttle control in accordance with the deviation between the target vehicle speed and the current vehicle speed, and performs control so that the vehicle speed of the host vehicle becomes the target vehicle speed.

  If it is determined that the distance between the vehicles cannot be maintained (too close) by the throttle-off braking force (engine brake) at the current gear position when the gradient is downhill, the target gear position is shifted from the ACC control unit 10. To the machine control unit 60. The transmission control unit 60 performs downshift control to the target gear position and maintains the inter-vehicle distance.

  Further, the ACC control unit 10 calculates the required deceleration of the host vehicle based on the inter-vehicle distance between the host vehicle and the preceding vehicle, the relative speed, and the deceleration of the preceding vehicle, and generates the requested deceleration. A necessary brake fluid pressure is calculated and transmitted to the brake control unit 20 as a required fluid pressure. The brake control unit 20 controls the hydraulic pressure of the brake system according to the required hydraulic pressure, and generates the necessary deceleration to decelerate the host vehicle.

  During such ACC control, if the laser radar 10a becomes unable to capture (lost) the preceding vehicle while the host vehicle is decelerating with the deceleration of the preceding vehicle, the vehicle speed and distance of the preceding vehicle are estimated. Then, the ACC control is continued by interpolating the vehicle speed and distance of the preceding vehicle based on the estimated data for a predetermined time. However, if the host vehicle is about to stop and the preceding vehicle is lost, if the control is continued with the interpolation processing of the estimated data uniquely, the ACC control is continued in a state where the inter-vehicle distance is close, so the preceding vehicle accelerates. Even if the situation starts, the brake control is unexpectedly applied, which gives the driver a feeling of strangeness.

  For this reason, in this system, when the preceding vehicle is lost during follow-up running in the low speed range, it is determined whether a certain degree of strong brake operation has continued in the low speed range, and interpolation processing is limited only to such a situation. The above-mentioned problem is addressed by continuing the ACC control according to. In other words, if the brake operation continues to a certain extent, it can be determined that the preceding vehicle decelerates and stops. In such a situation, the preceding vehicle is in a state where the inter-vehicle distance is short. The possibility of acceleration is low, and the driver's uncomfortable feeling due to unexpected brake control can be avoided.

  As a function relating to such lost processing during deceleration, the system includes functional units such as a lost determination unit 11, a nose dive determination unit 12, a control continuation determination unit 13, and a control continuation unit 14, as shown in FIG. ing. In the present embodiment, these functional units are provided in the ACC control unit 10, but each control unit connected via a network, for example, the ACC control unit 10, the brake control unit 20, and the engine The functions may be distributed by the control unit 70.

The lost determination unit 11 determines that the preceding vehicle has been lost during low-speed traveling when all of the following conditions (1-1), (1-2), and (1-3) are satisfied.
(1-1) A low-speed traveling area where the vehicle speed V1 of the preceding vehicle is equal to or lower than the threshold K1 (1-2) A low-speed traveling area where the vehicle speed V2 of the own vehicle is equal to or lower than the threshold K2 (1-3) The preceding radar can be detected by the laser radar 10a. The lost time continues for a predetermined time

  The laser radar 10a in the present embodiment mainly receives the reflected light of the laser beam from the reflector of the preceding vehicle and measures the vehicle speed and distance of the preceding vehicle. Therefore, there are cases where the reflected light of the laser cannot be received normally and the preceding vehicle cannot be detected due to factors such as the rear shape of the preceding vehicle or dirt. In particular, when traveling at a low speed, a nose dive may occur due to deceleration of the host vehicle, and the irradiation direction of the laser light may be directed downward from the preceding vehicle, and the preceding vehicle may not be detected. Therefore, the lost at the time of low speed traveling (for example, the preceding vehicle and the own vehicle are 10 km / m or less) is determined according to the conditions (1-1) to (1-3).

The nose dive determination unit 12 determines that the host vehicle has nose dive due to deceleration when the following conditions (2-1) to (2-3) are both satisfied. The threshold value for each parameter of the nose dive determination is a measured value in a state in which a certain degree of deceleration is continued for a predetermined time (for example, 2 G or more at 0.2 G) in consideration of the specifications such as the vehicle weight and pitch. Is a value determined based on
(2-1) The vehicle speed of the host vehicle is equal to or less than a threshold value K3 (K3 ≦ K1)
(2-2) The deceleration of the vehicle is greater than or equal to a preset threshold value (2-3) The brake is continuously operated for a set time or more.

  The control continuation determination unit 13 determines whether or not to continue the ACC control from the lost determination result by the lost determination unit 11 and the nose dive determination result by the nose dive determination unit 12. Even if it is determined that the preceding vehicle has been lost, if it is determined that the host vehicle has not been nose dive, it is determined that the ACC control has been released, the preceding vehicle has been lost, and the host vehicle has been nose dive. If determined, the control continuation unit 14 is instructed to continue the ACC control.

When the control continuation unit 14 receives a ACC control continuation instruction from the control continuation determination unit 13, for example, as shown in the following equation (1), the inter-vehicle distance and vehicle speed (relative speed) when the preceding vehicle is lost: The current inter-vehicle distance Ln is estimated by linear interpolation. Then, ACC control is continued based on the estimated inter-vehicle distance.
Ln = L0 + ΔV · t (1)
L0: Distance between vehicles when lost
ΔV: Vehicle speed (relative speed) of the preceding vehicle when lost
t: Lost time

  Next, the program processing related to the above-mentioned lost at deceleration will be described with reference to the flowchart of FIG.

  In the lost processing during deceleration, first, in first steps S1 and S2, it is checked whether the vehicle speed V1 of the preceding vehicle is lower than the threshold value K1 and whether the vehicle speed V2 of the own vehicle is lower than the threshold value K2, respectively. As a result, when the vehicle is in a low speed traveling state where the conditions of V1 <K1 and V2 <V2 are satisfied, the process proceeds to step S3, and when the condition is not satisfied, the present process is exited.

  In step S3, it is checked whether or not the state in which the preceding vehicle cannot be detected by the laser radar continues for a set time and it is determined that the preceding vehicle is lost. And when the time when the preceding vehicle cannot be detected is less than or equal to the set time, it is determined that the lost vehicle is temporarily lost and this process is skipped, and it is determined that the preceding vehicle has been lost continuously for more than the set time. The process proceeds from step S3 to step S4 to determine whether or not a nose dive of the vehicle has occurred.

  If it is determined in step S4 that the host vehicle is not nose dive, then the follow-up traveling to the preceding vehicle is canceled in step S5 and the process is exited. If it is determined that the host vehicle is nose dive, the process proceeds from step S4 to step S6, and the current inter-vehicle distance is estimated based on the inter-vehicle distance between the preceding vehicle just before the lost vehicle and the own vehicle and the vehicle speed of the preceding vehicle. .

  Thereafter, the process proceeds to step S7, and an engine throttle control command value and a brake fluid pressure control command value are calculated based on the deviation between the target inter-vehicle distance and the estimated value of the current inter-vehicle distance. In step S8, the control command values are output to the engine control unit 70 and the brake control unit 20 to execute acceleration / deceleration control.

  As described above, in the present embodiment, when the preceding vehicle is lost in the low speed range, the ACC control by the interpolation process is continued only in a situation where the brake operation to some extent continues for a predetermined time, otherwise the ACC control is performed. Is released. Therefore, ACC control is not continued and the brake is applied unexpectedly and strongly in situations where the preceding vehicle starts accelerating immediately before it stops and the preceding vehicle is lost. The situation can be avoided and the driver's uncomfortable feeling can be avoided.

  Moreover, if the brake operation continues to some extent, it can be determined that the preceding vehicle is decelerated and stopped, and the ACC control (brake control) is continued by interpolating the data of the preceding vehicle. , Can ensure safety. Further, in a situation where the preceding vehicle really disappears, it is possible to cancel the ACC control so as not to continue the control based on the estimated data, so that the driver is not bothered.

DESCRIPTION OF SYMBOLS 1 Cruise control system 10 ACC control unit 10a Laser radar 11 Lost determination part 12 Nose dive determination part 13 Control continuation determination part 14 Control continuation part

Claims (1)

An inter-vehicle distance control device that captures a preceding vehicle ahead of the host vehicle and maintains the inter-vehicle distance with respect to the preceding vehicle and performs follow-up running control,
A lost determination unit that determines that the preceding vehicle has been lost in a low-speed traveling range in which the vehicle speed of the preceding vehicle and the vehicle speed of the own vehicle are each equal to or less than a predetermined value;
It is determined that the vehicle has made a nose dive when the deceleration of the vehicle is equal to or greater than the threshold value, the brake is continuously operated for the set time or more , and the vehicle speed is equal to or less than the vehicle speed at which the preceding vehicle lost is determined. A nose dive determination unit to perform,
Even if it is determined from the lost determination result by the lost determination unit and the nose dive determination result by the nose dive determination unit whether to continue the follow-up control to the preceding vehicle, it is determined that the preceding vehicle has been lost, If the vehicle is determined not to nose dive, while releasing the following distance control to the preceding vehicle, is determined to be lost the preceding vehicle, and when the host vehicle is determined to have a nose dive Is a control continuation determination unit that instructs continuation of traveling control of the own vehicle;
A control continuation unit that estimates a distance and a vehicle speed of a preceding vehicle from a value just before the lost by a control continuation instruction from the control continuation determination unit, and that continues traveling control of the host vehicle based on the estimated value. The inter-vehicle distance control device.

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