JP2015093523A - Travel control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a travel control device which is capable of reducing deterioration of collision avoidance capability even when a brake lamp does not light up.SOLUTION: A travel control device includes a sensor for detecting an obstacle in the vicinity of an own vehicle and a control device which generates a brake force on the basis of a detection result by the sensor and lights a brake lamp while the brake force is generated. If a non-lighting state, in which the brake lamp does not light up, is detected while the brake force is generated, the control device reduces the brake force in comparison with when the non-lighting state is not detected and maintains the state in which the brake force is generated.

Description

  The present disclosure relates to a travel control device.

  2. Description of the Related Art Conventionally, a brake control unit that receives a brake operation signal from a collision prediction unit and operates a brake mechanism, and a lamp lighting circuit that receives a lamp lighting instruction signal from the collision prediction unit and lights a brake lamp, the brake control unit There is known a travel control device that exerts a vehicle braking force by a brake mechanism on condition that a brake lamp is lit when a brake operation signal is received (see, for example, Patent Document 1).

JP 2011-140265 A

  However, in the configuration described in Patent Document 1 described above, when the brake lamp is not turned on at the time of the brake operation based on the collision prediction, the brake control is released, so that the collision avoidance performance may be deteriorated.

  Accordingly, an object of the present disclosure is to provide a travel control device that can reduce a decrease in collision avoidance performance even when a brake lamp is not lit.

According to one aspect of the present disclosure, a sensor that detects an obstacle around the host vehicle;
A control device for generating a braking force based on a detection result of the sensor and lighting a brake lamp during the generation of the braking force;
When the control device detects a non-lighting state in which the brake lamp does not light during the generation of the braking force, the control device reduces the braking force compared to a case in which the non-lighting state is not detected. A travel control device is provided that maintains the generated state.

  According to the present disclosure, it is possible to obtain a travel control device that can reduce a decrease in collision avoidance performance even when the brake lamp is not lit.

It is a block diagram which shows schematic structure of the traveling control apparatus 1 by one Example. It is a flowchart which shows an example of the determination process of target deceleration. It is a figure which shows an example of a 1st map and a 2nd map. It is a flowchart which shows an example of the determination process of the target deceleration at the time of using the 1st map and 2nd map which are shown in FIG. 6 is a flowchart showing a modification of the target deceleration determination process shown in FIG. 2.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram illustrating a schematic configuration of a travel control device 1 according to an embodiment. The travel control device 1 includes a collision determination ECU (Electronic Control Unit) 10. The collision determination ECU 10 may be configured by a microcomputer or the like as with other ECUs. Note that the function of the collision determination ECU 10 may be realized by arbitrary hardware, software, firmware, or a combination thereof. For example, any part or all of the functions of the collision determination ECU 10 may be realized by an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a digital signal processor (DSP). Further, the function of the collision determination ECU 10 may be realized in cooperation with a plurality of ECUs.

  A forward radar sensor 12 is connected to the collision determination ECU 10. The front radar sensor 12 detects the state of a front obstacle (typically, the front vehicle) in front of the vehicle using radio waves (for example, millimeter waves), light waves (for example, lasers), or ultrasonic waves as detection waves. The front radar sensor 12 detects information indicating a relationship between the front obstacle and the own vehicle, for example, a relative speed, a relative distance, and an azimuth (lateral position) of the front obstacle based on the own vehicle at a predetermined cycle. When the front radar sensor 12 is a millimeter wave radar sensor, the millimeter wave radar sensor may be, for example, an electronic scan type millimeter wave radar. In this case, the front obstacle is detected using the Doppler frequency (frequency shift) of the radio wave. The relative speed of the front obstacle is detected using the delay time of the reflected wave, and the direction of the front obstacle is detected based on the phase difference of the received wave among the plurality of receiving antennas. These detection data are transmitted to the collision determination ECU 10 at a predetermined cycle. The function of the front radar sensor 12 (for example, the position calculation function of the front obstacle) may be realized by the collision determination ECU 10.

  Note that an image sensor may be used instead of or in addition to the front radar sensor 12. The image sensor includes a camera and an image processing device including an image sensor such as a charge-coupled device (CCD) and a complementary metal oxide semiconductor (CMOS), and recognizes the state of a front obstacle. The camera of the image sensor may be a stereo camera. Based on the image recognition result, the image sensor detects information indicating a relationship between the front obstacle and the own vehicle, for example, speed and position information of the front obstacle based on the own vehicle at a predetermined cycle. The position information of the front obstacle may include information on the position (distance) of the front obstacle in the front-rear direction of the host vehicle and information on the lateral position of the front obstacle in the lateral direction (width direction). The lateral position of the front obstacle may be calculated based on the lateral center position of the pixel set related to the forward obstacle, or may be calculated as a range between the leftmost lateral position and the rightmost lateral position. Good. Information (detection result) acquired by the image sensor may be transmitted to the collision determination ECU 10 at a predetermined frame period, for example. Note that the image processing function of the image processing apparatus (for example, the position calculation function of the front obstacle) may be realized by the collision determination ECU 10.

  Various electronic components in the vehicle may be connected to the collision determination ECU 10 via an appropriate bus such as a CAN (controller area network). In the example shown in FIG. 1, the collision determination ECU 10 is connected to a brake ECU 20 that controls a brake device (not shown), an engine ECU 22 that controls an engine (not shown), a meter ECU 24, and the like. A part of the function of the brake ECU 20 may be realized by the collision determination ECU 10.

  Various sensors such as an acceleration sensor 16, a wheel speed sensor 18, and a rudder angle sensor (not shown) may be connected to the collision determination ECU 10. As shown in FIG. 1, the acceleration sensor 16 and the wheel speed sensor 18 may be directly connected to the collision determination ECU 10 or may be connected via another ECU. The collision determination ECU 10 detects acceleration generated in the vehicle based on information from the acceleration sensor 16. The acceleration sensor 16 may be a sensor that detects acceleration in three axis directions. The collision determination ECU 10 detects the vehicle speed based on information from the wheel speed sensor. The vehicle speed may be calculated based on other information (for example, the rotational speed of the output shaft of the transmission) instead of or in addition to the information from the wheel speed sensor.

  A brake lamp 30 and a brake actuator 40 are connected to the brake ECU 20.

  The brake lamp 30 is provided at the rear part of the vehicle. The brake lamp 30 may include a high-mount brake lamp in addition to the two brake lamps provided on the left and right sides of the rear portion of the vehicle. The lighting of the brake lamp 30 may be controlled by the brake ECU 20. For example, the brake ECU 20 may control the lighting state of the brake lamp 30 by turning on / off a relay 32 provided between the power source and the brake lamp 30.

  The brake actuator 40 may include a pump that generates high-pressure oil (and a motor that drives the pump), various valves (such as a solenoid valve for controlling wheel cylinder pressure and the like), and the like. The hydraulic circuit configuration of the braking device is arbitrary. The hydraulic circuit of the braking device may be any configuration that can increase the wheel cylinder pressure regardless of the amount of depression of the brake pedal by the driver (that is, a configuration that can realize automatic braking control). The high-pressure hydraulic source (pump or accumulator that generates high-pressure oil) may be provided. Further, a circuit configuration typically used in a brake-by-wire system represented by ECB (Electric Control Braking system) may be adopted.

  Next, an example of automatic braking control that may be executed by the collision determination ECU 10 and the brake ECU 20 will be described.

  The collision determination ECU 10 determines an automatic braking control start condition based on information from the front radar sensor 12. The automatic braking control start condition is arbitrary. For example, in the collision avoidance control with the front obstacle, the time until the collision with the front obstacle: TTC (Time to Collision) is calculated, which is satisfied when the calculated TTC falls below a predetermined value (for example, 1 second). It may be. In this case, the collision determination ECU 10 calculates TTC for a front obstacle in a predetermined direction (lateral position) based on the detection result from the front radar sensor 12, and the calculated TTC has a predetermined value (for example, 1 second). When it falls below, an automatic braking control request is output. Note that the TTC may be derived by dividing the relative distance to the front obstacle by the relative speed with respect to the front obstacle. In addition, in automatic driving control (for example, ACC: Adaptive Cruise Control), for example, it is satisfied when the magnitude of deceleration necessary to maintain a predetermined lower distance between the vehicle ahead and a predetermined vehicle exceeds a predetermined value. It may be.

The automatic braking control start condition may be satisfied when it is determined that a collision with a front obstacle (including a vehicle ahead) is unavoidable. That is, it may be satisfied when the possibility of a collision with a front obstacle is a predetermined level (in this case, 100%) or more. A method for determining whether or not a collision with a front obstacle is unavoidable is widely known in the field of pre-crash safety, and various methods may be adopted. For example, for each automatic braking control start timing (TTC), a collision avoidance relative speed may be calculated in advance, and a collision unavoidable determination map may be created based on the calculated relative speed. In this case, the collision determination ECU 10 may determine whether or not the collision with the front obstacle is unavoidable by referring to the collision unavoidable determination map based on the relative speed with the front obstacle and the TTC. . Specifically, the deceleration G (m / s ² ) and the deceleration speed V (m / s) t seconds after the start of the automatic braking control are the maximum speed G _MAX (m / s ² ) and the decrease. When the velocity gradient J (m / s ³ ) is established, the following relationship is established.
When _{t ≦ G MAX / J, G} = Jt, V = J × t 2/2
When G _MAX / J <t, G = G _MAX , V = G _MAX ² / (2J) + G _MAX (t−G _MAX / J)
In this case, a collision unavoidable determination map may be created by regarding a relative speed larger than the deceleration speed V after t seconds as a collision unavoidable relative speed. Alternatively, the collision inevitable determination map using the relative distance as a parameter may be created by obtaining the relative distance by integrating the deceleration speed V. Alternatively, as a more complicated algorithm, acceleration of a front obstacle may be considered.

  When the automatic braking control start condition is satisfied, the collision determination ECU 10 may continue to supply the automatic braking control request to the brake ECU 20 until the automatic braking control end condition is satisfied. The automatic braking control end condition is arbitrary. For example, when a collision is detected, the vehicle speed becomes 0 km / h, or when TTC exceeds 1.5 [seconds], an automatic braking control request is issued. It may be satisfied when it continues for a predetermined time (for example, 3 seconds) or more.

  The collision determination ECU 10 calculates a target control value at the time of automatic braking control, and supplies the target control value to the brake ECU 20 together with an automatic braking control request. The target control value may be supplied to the brake ECU 20 in a manner included in the automatic braking control request. For example, the state where the target control value is larger than 0 may be a state where an automatic braking control request is generated. Here, the automatic braking control is, for example, control that generates a braking force (that is, increases the wheel cylinder pressure of the wheel cylinder) in a situation where the driver does not operate the brake pedal. Therefore, the target control value during automatic braking control is a value determined based on factors other than the operation amount of the brake pedal. A method for determining the target control value will be described later. The target control value may be an arbitrary physical quantity, and may be, for example, a deceleration, a hydraulic pressure, a pressure increase gradient, or the like. Hereinafter, as an example, it is assumed that the target control value is a target deceleration.

  The brake ECU 20 controls the brake actuator 40 in response to an automatic braking control request from the collision determination ECU 10, and generates a braking force so that the target control value is realized (that is, executes automatic braking control). In this case, feedback control (for example, PID control) may be used as the automatic braking control. The brake ECU 20 lights the brake lamp 30 during execution of automatic braking control. For example, the brake ECU 20 maintains the relay 32 provided between the power source and the brake lamp 30 during the execution of the automatic braking control (while receiving the automatic braking control request), so that the brake lamp 30 Maintain lighting status.

  FIG. 2 is a flowchart illustrating an example of a target deceleration determination process that may be executed by the collision determination ECU 10. The process shown in FIG. 2 may be repeatedly executed at predetermined intervals in order to determine a target deceleration for automatic braking control during execution of automatic braking control.

  In step 200, it is determined whether or not the brake lamp 30 is in a non-lighting state. Normally, during execution of automatic braking control, the brake lamp 30 is turned on as described above. The non-lighting state of the brake lamp 30 occurs due to a failure (for example, open fixation) of the relay 32 or the like. In addition, when the relay 32 fails, the whole brake lamp 30 will be in a non-lighting state. That is, in the configuration in which the brake lamp 30 includes a high-mount brake lamp in addition to the two brake lamps provided on the left and right sides of the rear part of the vehicle, when the relay 32 fails, all of these lamps are not lit. It becomes. Hereinafter, as an example, the unlit state of the brake lamp 30 means the unlit state of the brake lamp 30 as a whole. Whether or not the brake lamp 30 is not lit may be determined based on a current value between the relay 32 and the brake lamp 30. The unlit state of the brake lamp 30 may be detected by the brake ECU 20. In this case, the collision determination ECU 10 determines whether or not the brake lamp 30 is unlit based on information from the brake ECU 20. May be determined. When the brake lamp 30 is in the non-lighting state, the process proceeds to step 202. In other cases (that is, when the brake lamp 30 is in the lighting state), the process proceeds to step 204.

  In step 202, a target deceleration is calculated based on the first map. The first map has a characteristic that the target deceleration under the same condition is calculated lower than that of the second map described later. That is, the first map has a smaller target deceleration that can be calculated than the second map described later. For example, the first map may be a map that defines an upper limit value of the target deceleration (hereinafter referred to as “upper limit target deceleration”). In this case, the first map has a lower upper limit target deceleration under the same conditions as compared to the second map. However, the upper limit target deceleration is set to a value significantly larger than 0. The upper limit target deceleration may always be constant. In this case, the first map itself is not necessary, and the collision determination ECU 10 may calculate the target deceleration based on information from the front radar sensor 12 so as not to exceed a predetermined upper limit target deceleration. A specific example of the first map will be described later.

  In step 204, a target deceleration is calculated based on the second map. The second map has a characteristic that the target deceleration under the same condition is calculated higher than that of the first map. A specific example of the second map will be described later.

  According to the example shown in FIG. 2, the braking force generated by the automatic braking control when it is detected that the brake lamp 30 is not lit during execution of the automatic braking control, compared to the case where it is not detected. (For example, the braking force is set to a value significantly larger than 0). That is, according to the example shown in FIG. 2, even if it is detected that the brake lamp 30 is in the non-lighting state during execution of the automatic braking control, the braking force is smaller than that in the case where it is not detected. Braking control is continued. Thereby, even when the brake lamp 30 is not turned on during the automatic braking control, it is possible to reduce a decrease in collision avoidance performance (including collision damage reduction performance).

  In the example shown in FIG. 2, the determination in step 200 is performed after a predetermined time corresponding to the time required for the operation of the relay 32 (from the start of the automatic braking control) in consideration of the delay for the time required for the operation of the relay 32. It may be executed after a predetermined time. In this case, the determination in step 200 may always be a negative determination from the start of automatic braking control to a predetermined time.

  FIG. 3 is a diagram illustrating an example of the first map and the second map, where (A) illustrates an example of the first map, and (B) illustrates an example of the second map. As described above, the first map is used when the unlit state of the brake lamp 30 is detected, and the second map is used when the unlit state of the brake lamp 30 is not detected.

  In the example shown in FIG. 3, the first map and the second map represent the relationship between the duration of the automatic braking control and the upper limit target deceleration. The duration of automatic braking control is the time from the start of automatic braking control to the current time, and is hereinafter referred to as “automatic braking duration”. In FIG. 3, the upper limit target deceleration is shown in magnitude (ie, the sign of the deceleration is positive). The minimum relationship of the upper limit target deceleration is based on the magnitude (absolute value).

  FIG. 3 shows a curve dividing the region P and the region Q. This curve represents the upper limit target deceleration according to the automatic braking duration. A region Q exceeding the upper limit target deceleration is a region where the risk of the following vehicle (risk of the following vehicle due to the automatic braking control of the own vehicle) is higher than a predetermined reference. The predetermined standard may be based on, for example, functional safety ISO 26262. In ISO26262, the risk for failure is classified by ASIL (Automotive Safety Integrity Level). QM (Quality Management) <A <B <C <D is required in order of high level safety measures. In this case, the region P may correspond to the QM region. Alternatively, the area P may correspond to an area including both QM and A, or may be another area.

  The region Q in the first map is wider than the region Q in the second map. This is because when the brake lamp 30 is not lit, the response time of the driver of the succeeding vehicle with respect to the automatic braking of the host vehicle is likely to be delayed, and the risk of rear-end collision of the succeeding vehicle is increased accordingly. In the example shown in FIG. 3, the region Q in the first map is a mode that completely includes the region Q in the second map, and is wider than the region Q in the second map. More specifically, the region Q in the first map starts from the automatic braking duration time t1, and the region Q in the second map starts from the automatic braking duration time t2, where t2> t1. That is, the upper limit target deceleration (finite value) is generated earlier in the first map than in the second map. In the example shown in FIG. 3, in the first map, when the automatic braking duration exceeds a predetermined value, the upper limit target deceleration is settled to the minimum value G1 (> 0), and in the second map, the automatic braking duration is a predetermined value. If it exceeds, the upper limit target deceleration settles to the minimum value G2, but the minimum value G2 is larger than the minimum value G1 (ie, G2> G1> 0).

  Note that the characteristics of the first map and the second map shown in FIG. 3 are merely examples, and various changes can be made. For example, the QM area itself is determined based on criteria such as degree of harm (severity), exposure rate / exposure level (exposure), avoidability (controllability), and the like, and there are a variety of determination methods.

  FIG. 4 is a flowchart showing an example of target deceleration determination processing when the first map and the second map shown in FIG. 3 are used. The process shown in FIG. 4 may be employed as the process of step 202 and step 204 in FIG.

  In step 400, a target deceleration is calculated based on information from the front radar sensor 12. A method of calculating the target deceleration based on information from the front radar sensor 12 is widely known, for example, in the field of pre-crash safety, and is various, and any method may be used. For example, the target deceleration may be calculated in a pattern that increases from the start of automatic braking control to a predetermined target deceleration (for example, a maximum realizable deceleration). In this case, the information from the front radar sensor 12 is not directly used for calculating the target deceleration, but is used for detecting a collision inevitable state. Alternatively, the target deceleration may be calculated based on TTC, current vehicle speed, automatic braking duration, and the like.

  In step 402, the automatic braking duration time is calculated. The automatic braking duration time may be calculated (timed) using a timer started at the start of automatic braking control.

  In step 404, an upper limit target deceleration corresponding to the automatic braking duration calculated in step 402 is calculated. At this time, the upper limit target deceleration is calculated based on the first map or the second map. That is, when the non-lighting state of the brake lamp 30 is detected, the upper limit target deceleration corresponding to the automatic braking duration calculated in step 402 is calculated based on the first map, while the brake lamp 30 When the unlighted state is not detected, the upper limit target deceleration corresponding to the automatic braking duration calculated in step 402 is calculated based on the second map.

  In step 406, it is determined whether or not the target deceleration calculated in step 400 is equal to or less than the upper limit target deceleration calculated in step 404. If the target deceleration is less than or equal to the upper limit target deceleration, the processing of the current cycle is terminated as it is. In this case, the target deceleration calculated in step 400 is used as it is for automatic braking control. On the other hand, if the target deceleration is not less than or equal to the upper limit target deceleration, the process proceeds to step 408.

  In step 408, the target deceleration is corrected to the upper limit target deceleration. That is, the upper limit guard for the target deceleration functions, and the upper limit target deceleration is used for the automatic braking control instead of the target deceleration calculated in step 400.

  As described above, according to the example shown in FIG. 4, the upper limit target is selectively used by selectively using the first map or the second map shown in FIG. 3 according to whether or not the unlighted state of the brake lamp 30 is detected. Deceleration can be calculated. Thus, depending on whether or not the non-lighting state of the brake lamp 30 is detected, the automatic braking control can be executed based on an appropriate upper limit target deceleration considering the rear-end collision risk of the following vehicle.

  FIG. 5 is a flowchart showing a modification of the target deceleration determination process shown in FIG.

  The target deceleration determination process shown in FIG. 5 is mainly different from the target deceleration determination process shown in FIG. 2 in that steps 503 and 506 are added. Each process of step 500, step 502, and step 504 shown in FIG. 5 may be the same as each process of step 200, step 202, and step 204 shown in FIG. In the following, a configuration unique to the target deceleration determination process shown in FIG. 5 will be mainly described.

  If a negative determination is made in step 500, the process proceeds to step 503. In step 503, it is determined whether or not the vehicle has returned from the unlighted state. That is, it is determined whether or not the unlit state of the brake lamp 30 was detected before the previous cycle. Note that such a return can be caused by, for example, eliminating mechanical fixation of the relay 32. When it returns from a non-lighting state, it progresses to step 506, and when that is not right (when the non-lighting state of the brake lamp 30 is not detected before the last period), it progresses to step 504.

  In step 506, switching from the first map to the second map is performed gradually. As a result, when the brake lamp 30 subsequently returns from the unlighted state to the lit state, the high collision avoidance performance when the brake lamp 30 is in the lit state is restored while preventing the driver from feeling uncomfortable. Can do. If switching has already been performed before the previous cycle, the switching may be taken over in the current cycle. If the switching that has been performed since the previous cycle has already been completed, the target deceleration is calculated based on the second map in the current cycle as in step 504.

In addition, the switching mode (gradual change mode) from the first map to the second map in step 506 is arbitrary. For example, switching from the first map to the second map may be realized by taking two or more processing cycles, for example. Specifically, it may be as follows.
(Upper target deceleration) = (Tk / T2) × ( _Gup2 - _Gup1 ) + _Gup1 (Tk <T2)
(Upper target deceleration) = G _up2 (Tk ≧ T2)
Here, G _up1 is an upper limit target deceleration according to the first map, G _up2 is an upper limit target deceleration according to the second map, Tk is an elapsed time from the return time point, and T2 is a predetermined value. Time (gradual change period). In this case, switching from the first map to the second map is realized over a predetermined time T2.

  Further, the time used for switching (gradual change period T2) may be varied according to the automatic braking continuation time at the time of return from the non-lighting state to the lighting state. For example, when the first map and the second map shown in FIG. 3 are used, the upper limit target deceleration according to the first map and the second map with respect to the automatic braking duration at the time of return from the non-lighting state to the lighting state It may be varied according to the difference from the upper limit target deceleration. In this case, the gradual change period may be set longer as the difference between the upper limit target deceleration according to the first map and the upper limit target deceleration according to the second map is larger.

In addition, the switching mode (gradual variation mode) from the first map to the second map in step 506 may be realized using not the time but the travel distance as a parameter. For example, it may be as follows.
(Upper limit target deceleration) = (Dk / D2) × ( _Gup2 - _Gup1 ) + _Gup1 (Dk <D2)
(Upper target deceleration) = G _up2 (Dk ≧ D2)
Here, Dk is a travel distance from the time of return, and D2 is a predetermined distance (gradual change distance). In this case, switching from the first map to the second map is realized over the gradual change distance D2.

  According to the example shown in FIG. 5, when the brake lamp 30 returns from the non-lighting state to the lighting state afterwards, the brake lamp 30 is switched on from the first map to the lighting state when the brake lamp 30 is in the lighting state. High collision avoidance performance can be restored. At this time, by gradually switching from the first map to the second map, it is possible to reduce a rapid increase in deceleration due to the switching. For example, when the first map and the second map shown in FIG. 3 are used, for example, when the brake lamp 30 returns from the unlit state to the lit state when the automatic braking duration time is t2 (see FIG. 3), When switching to the second map at the time, as shown in FIGS. 3A and 3B, the upper limit target deceleration increases rapidly. Therefore, if the upper limit guard functioning at the upper limit target deceleration is functioning at this point, a large change in braking force occurs due to a sudden increase in the upper limit target deceleration, causing the driver to feel strange (a sudden increase in deceleration). Impact). On the other hand, according to the example shown in FIG. 5, it is possible to reduce the sudden increase in the upper limit target deceleration and to reduce the uncomfortable feeling to the driver.

  In the example shown in FIG. 5, as a preferred embodiment, when the brake lamp 30 later returns from the non-lighting state to the lighting state, the switching from the first map to the second map is gradually performed. The switching from the first map to the second map may be performed immediately.

  Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope described in the claims. It is also possible to combine all or a plurality of the components of the above-described embodiments.

  For example, in the above-described embodiment, when the non-lighting state of the brake lamp 30 is detected, the horn may be automatically sounded in order to accelerate the reaction time of the driver of the following vehicle. In this case, the second map may be used, or a map having a lower limit of the upper limit target deceleration compared to the first map (for example, an intermediate characteristic between the first map and the second map). It is also possible to use a map of At this time, the sound pressure of the horn may be adjusted, and the limit degree of the upper limit target deceleration may be varied according to the sound pressure of the horn. For example, the limit degree of the upper limit target deceleration may be varied according to the sound pressure of the horn in such a manner that the limit degree of the upper limit target deceleration becomes smaller as the sound pressure of the horn becomes higher.

  In the above-described embodiment, when a non-lighting state of the brake lamp 30 is detected, a hazard lamp (not shown) may be automatically turned on in order to speed up the reaction time of the driver of the following vehicle. Good. In this case, the second map may be used, or a map having a lower limit of the upper limit target deceleration compared to the first map (for example, an intermediate characteristic between the first map and the second map). It is also possible to use a map of

  In the above-described embodiment, the upper limit target deceleration is varied depending on whether the brake lamp 30 is in the non-lighting state or in the lighting state. In addition to or in place of it, the brake lamp 30 is in the non-lighting state or in the lighting state. In accordance with this, the increase gradient of the target deceleration may be varied. In this case, the increase gradient of the target deceleration may be reduced when the brake lamp 30 is not lit than when the brake lamp 30 is lit.

  In the above-described embodiment, the upper limit target deceleration is varied depending on whether the brake lamp 30 is in the non-lighting state or in the lighting state. In addition to or in place of it, the brake lamp 30 is in the non-lighting state or in the lighting state. Accordingly, the start timing of the automatic braking control may be varied. In this case, the start timing of the automatic braking control may be delayed when the brake lamp 30 is in the non-lighting state than when the brake lamp 30 is in the lighting state.

  In the above-described embodiment, the upper limit target deceleration is varied depending on whether the brake lamp 30 is in the non-lighting state or the lighting state. However, when the brake lamp 30 is in the non-lighting state, the brake lamp 30 is turned on. It is also possible to correct the target deceleration calculated in the state (correct in the direction of reduction). The correction may be performed at a constant rate, or may be performed at a rate that changes according to the automatic braking duration, for example.

  In the above-described embodiment, the upper limit target deceleration is varied depending on whether the brake lamp 30 is in the non-lighting state or the lighting state. However, the vehicle speed is reduced depending on whether the brake lamp 30 is in the non-lighting state or the lighting state. The upper limit value for the value may be varied. The vehicle speed reduction value is a vehicle speed reduction value (deceleration speed) obtained by subtracting the current vehicle speed from the vehicle speed at the start of automatic braking control. The collision determination ECU 10 may stop or suppress the automatic braking control when the vehicle speed reduction value exceeds the upper limit value. In this case, the upper limit value for the vehicle speed reduction value may be smaller when the brake lamp 30 is in the non-lighting state than when the brake lamp 30 is in the lighting state.

  In the embodiment described above, the automatic braking control may be canceled (canceled) when the driver operates the brake pedal during the automatic braking control. Alternatively, when the driver operates the brake pedal during the automatic braking control, the automatic braking control is performed until the target control value corresponding to the operation of the brake pedal exceeds the target control value related to the automatic braking control. May be maintained.

  In the embodiment described above, the automatic braking control may include preliminary braking control that is executed prior to the automatic braking control. That is, the automatic braking control may be executed so as to generate a necessary braking force from the beginning, but first, a light and gentle braking force is generated (preliminary braking control), and then a necessary braking force is generated. (This automatic braking control) may be executed. The start condition of this automatic braking control may be the same as the above-described automatic braking control start condition. The start condition of the preliminary braking control may be a condition (a condition that is easily satisfied) that is milder than the starting condition of the automatic braking control. In this case, the automatic braking duration time may be counted from the start time of the preliminary braking control, or may be counted from the start time of the automatic braking control. In this configuration, there is a high possibility that the unlit state of the brake lamp 30 can be detected during the preliminary braking control. When the non-lighting state of the brake lamp 30 is detected during the preliminary braking control, a map (for example, the first map and the first target map) that has a lower limit of the upper limit target deceleration compared to the first map while quickly decelerating. An intermediate property map between the second maps may be used.

  In the above-described embodiment, the present invention relates to a front obstacle (front radar sensor 12), but the same applies to an obstacle other than the front, for example, a side obstacle (for example, detected by a side radar sensor). Applicable.

1 Traveling Control Device 10 Collision Determination ECU
12 Front radar sensor 20 Brake ECU
30 Brake lamp 32 Relay 40 Brake actuator

Claims (6)

A sensor that detects obstacles around the vehicle,
A control device for generating a braking force based on a detection result of the sensor and lighting a brake lamp during the generation of the braking force;
When the control device detects a non-lighting state in which the brake lamp does not light during the generation of the braking force, the control device reduces the braking force compared to a case in which the non-lighting state is not detected. A travel control device that maintains the generation state.   The travel control device according to claim 1, wherein the control device reduces the braking force as the duration of the state in which the braking force is generated increases.   The control device, after detecting the non-lighting state, when detecting lighting of the brake lamp, returns the reduced braking force to the braking force generated when the non-lighting state is not detected, The travel control device according to claim 1 or 2. When the control device detects the non-lighting state, the control device uses the first map that represents the relationship between the duration of the generation state of the braking force and the upper limit value of the braking force that can be generated. When the magnitude of power is determined and the non-lighting state is not detected, using a second map that represents the relationship between the duration of the braking force generation state and the upper limit value of the braking force that can be generated, Decide how much braking force to generate,
The upper limit value of the braking force for a predetermined duration in the first map is lower than the upper limit value of the braking force for the same duration in the second map. The travel control device described.   The first map and the second map have a characteristic that the upper limit value of the braking force decreases as the duration time increases, and the continuation when the upper limit value of the braking force in the first map is generated. The travel control device according to claim 4, wherein the time is shorter than the duration when the upper limit value of the braking force in the second map is generated.   The travel control device according to claim 5, wherein an upper limit value of the braking force for an arbitrary duration in the first map is equal to or less than an upper limit value of the braking force for the same duration in the second map.

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