JP5458051B2 - Vehicle driving support device - Google Patents

Description

  The present invention relates to a vehicle driving support device that performs travel control through throttle control or brake intervention control.

  Conventionally, various proposals for driving support devices that recognize the environment outside the vehicle using a millimeter wave radar, infrared laser radar, stereo camera, monocular camera, etc., and control the driving of the vehicle based on the recognized environment outside the vehicle As one of the functions of such traveling control, a function of performing tracking traveling control on a detected preceding vehicle when a preceding vehicle is detected (captured) in front of the host vehicle is widely known. In general, such follow-up control is widely put into practical use as part of ACC (Adaptive Cruise Control) with inter-vehicle distance control. In ACC, follow-up is detected when a preceding vehicle is detected in front of the host vehicle. When the control is performed and the preceding vehicle is not detected, the constant speed traveling control at the vehicle speed set by the driver is performed.

  This type of driving support device sets a target acceleration (acceleration / deceleration) according to, for example, the relative speed between the preceding vehicle and the own vehicle or the speed deviation between the set vehicle speed and the own vehicle speed during the execution of ACC. Then, acceleration corresponding to the target acceleration is generated by opening control of the electronically controlled throttle valve (engine output control). Furthermore, when the driving support device determines that sufficient acceleration (deceleration) cannot be obtained by only the engine output control during downhill, etc., the driving support device is used in accordance with the target acceleration by using automatic braking control together. Generate acceleration (deceleration).

  By the way, during the execution of such ACC, the shift control for the automatic transmission is basically performed based on the relationship between the vehicle speed and the throttle opening, etc., but there is insufficient driving torque when climbing or engine braking when descending. In order to suppress fluctuations in the vehicle speed due to insufficient braking force due to braking, a number of techniques have been proposed for driving down down the gear ratio of an automatic transmission forcibly when a road gradient exceeding a predetermined level is detected. (For example, refer to Patent Document 1). For example, by performing such downshift control during deceleration on a downhill road, it is possible to suitably suppress the automatic intervention frequency of the brake, the intervention time, and the like.

JP 11-34689 A

  However, for example, when a road gradient is detected using an acceleration sensor, a gradient sensor, or the like, these sensors are susceptible to errors due to the influence of temperature changes. Further, the road gradient can be estimated based on, for example, the relationship between the running resistance of the own vehicle and the wheel driving force, but the road gradient estimated in this way is also the vehicle weight, road surface condition, etc. It is easy to be affected by the disturbances and errors.

  Therefore, a relatively gentle slope road may not be recognized by the driving support device. For example, if the vehicle is not recognized while traveling on a relatively gentle downward slope, the forced down As a result, the shift is not performed, and as a result, the intervention of the automatic brake is performed for a long time, and the brake force may fade.

  The present invention has been made in view of the above circumstances, and a vehicle capable of performing good vehicle speed control without increasing the automatic intervention time of the brake even when the downshift of the transmission on the slope road is not performed. An object of the present invention is to provide a driving support apparatus.

  A vehicle driving support apparatus according to an aspect of the present invention calculates a basic target acceleration based on a relationship between an actual vehicle speed and a target vehicle speed, and sets a target acceleration based on the basic target acceleration, Engine control means for controlling engine output through throttle valve opening control based on target acceleration, and braking when sufficient deceleration cannot be obtained by only engine output control for the target acceleration set to the negative side And a brake control means for generating braking force by automatic intervention control of the vehicle, wherein when it is determined that the automatic intervention control of the brake has continued for a preset time or longer, the target A rate of maintaining the target deceleration until the basic target acceleration exceeds the positive set value by changing the acceleration to a preset negative value. Those comprising an interrupt control means for performing control.

  According to the vehicle driving support device of the present invention, it is possible to perform good vehicle speed control without increasing the automatic intervention time of the brake even when the transmission is not downshifted on a gradient road.

Schematic configuration diagram of a vehicle driving support device Flow chart showing target acceleration calculation routine Explanatory drawing showing the relationship between target acceleration and basic target acceleration by interrupt control

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a vehicle driving support device, FIG. 2 is a flowchart showing a target acceleration calculation routine, and FIG. 3 is a graph showing the target acceleration and basic target acceleration by interrupt control. It is explanatory drawing which shows a relationship.

  In FIG. 1, reference numeral 1 denotes a vehicle such as an automobile (own vehicle). The vehicle 1 has a driving support device 2 having an ACC (Adaptive Cruise Control) function as a travel control function. Is installed.

  For example, the driving support device 2 includes a stereo camera 3, a stereo image recognition device 4, and a travel control unit 5. In the traveling control unit 5 of the stereo camera assembly 2a, various in-vehicle control units such as an engine control unit (E / G_ECU) 7, a brake control unit (BRK_ECU) 8, and a transmission control unit (T / M_ECU) 9 are mutually connected. It is connected so that it can communicate.

  The stereo camera 3 is composed of a pair of left and right CCD cameras using a solid-state imaging device such as a charge coupled device (CCD) as a stereo optical system. Each of these sets of CCD cameras is attached to the front of the ceiling in the vehicle interior with a fixed interval, and subjects the object outside the vehicle to stereo imaging from different viewpoints, and outputs the captured image information to the stereo image recognition device 4.

  The stereo image recognition device 4 receives image information from the stereo camera 3 and, for example, the vehicle speed V from the T / M_ECU 9. The stereo image recognition device 4 recognizes forward information such as three-dimensional object data and white line data ahead of the host vehicle 1 based on image information from the stereo camera 3, and estimates the host vehicle traveling path based on the recognition information and the like. To do. Furthermore, the stereo image recognition device 4 performs detection of a preceding vehicle on the own vehicle traveling path based on the recognized three-dimensional object data or the like.

  Here, the stereo image recognition device 4 performs processing of image information from the stereo camera 3 as follows, for example. First, distance information is generated on the basis of the principle of triangulation from a corresponding positional shift amount for a pair of stereo images obtained by capturing the traveling direction of the host vehicle with the stereo camera 3. Then, a well-known grouping process is performed on the distance information, and the distance information subjected to the grouping process is compared with previously stored three-dimensional road shape data, solid object data, etc. Sidewall data such as guardrails and curbs, and three-dimensional object data such as vehicles are extracted along the way. Furthermore, the stereo image recognition device 4 estimates the host vehicle travel path based on the white line data, the side wall data, and the like, and is a three-dimensional object existing on the host vehicle travel path, and has a predetermined speed in substantially the same direction as the host vehicle 1. A vehicle moving at (for example, 0 km / h or more) is extracted (detected) as a preceding vehicle. When a preceding vehicle is detected, as preceding vehicle information, the preceding vehicle distance D (= inter-vehicle distance), the preceding vehicle speed Vf (= (change ratio of the inter-vehicle distance D) + (own vehicle speed V)), The preceding vehicle acceleration af (= differential value of the preceding vehicle speed Vf) and the like are calculated. Of the preceding vehicles, in particular, a vehicle whose speed Vf is not more than a predetermined value (for example, 4 km / h or less) and is not accelerated is recognized as a preceding vehicle in a substantially stopped state.

  The travel control unit 5 receives, for example, various recognition information regarding the front outside the vehicle from the stereo image recognition device 4 and the own vehicle speed V from the T / M_ECU 9.

  Further, for example, various setting information of the driver set through the cruise control switch 15 is input to the traveling control unit 5 via the E / G_ECU 7. In the present embodiment, the cruise control switch 15 is, for example, an operation switch including a push switch and a toggle switch disposed on the steering wheel, and a cruise switch “CRUISE” which is a main switch for turning on / off the operation of the ACC. A cancel switch “CANCEL” for canceling ACC, a set switch “SET / −” for setting the speed of the host vehicle at that time as the set vehicle speed Vset, and a mode of the inter-vehicle distance between the preceding vehicle and the host vehicle. And a resume switch “RES / +” for resetting the previously stored set vehicle speed Vset. In the present embodiment, any one of “long”, “medium”, and “short” is set as the inter-vehicle distance mode, and the traveling control unit 5 varies depending on the mode, for example, according to the own vehicle speed V. The target tracking distance Dtrg is set.

  Then, the cruise switch of the cruise control switch 15 is turned on, the set vehicle speed Vset desired by the driver is set through a set switch or the like, and a mode for setting the tracking target distance Dtrg is set through the inter-vehicle distance setting switch. And the traveling control unit 5 performs ACC.

  As this ACC, when the preceding vehicle is not detected by the stereo image recognition device 4, the traveling control unit 5 performs constant speed traveling control for converging the own vehicle speed V to the set vehicle speed Vset. Further, when the stereo image recognition device 4 recognizes the preceding vehicle during the constant speed traveling control, the traveling control unit 5 follows the following traveling control (the tracking distance control for converging the inter-vehicle distance D to the following target distance Dtrg). (Including tracking stop and tracking start).

  That is, when the constant speed traveling control is started, the traveling control unit 5 calculates the target acceleration a1 for converging the host vehicle speed V to the set vehicle speed Vset.

  More specifically, the travel control unit 5 calculates a vehicle speed deviation Vsrel (= Vset−V) between the host vehicle speed V and the set vehicle speed Vset, and refers to a preset map or the like, for example, to thereby calculate the vehicle speed deviation. A target acceleration a1 corresponding to Vsrel and the vehicle speed V is calculated. For example, when the vehicle speed deviation Vsrel is a positive value, the target acceleration a1 is set to a larger value as the vehicle speed deviation Vsrel increases within the range of the upper limit value according to the host vehicle speed V. On the other hand, for example, when the vehicle speed deviation Vsrel is a negative value, the target acceleration a1 is set to a smaller value within the range of the lower limit value corresponding to the host vehicle speed V (the vehicle speed deviation Vsrel is negative). The larger the value is, the larger the value is set on the deceleration side).

  Further, when shifting from the constant speed traveling control to the following traveling control, the traveling control unit 5 calculates a target acceleration a2 for converging the inter-vehicle distance D to the following target distance Dtrg in addition to the above target acceleration a1.

  More specifically, the travel control unit 5 stores, for example, a map for setting the target tracking distance Dtrg corresponding to the modes “short” and “long” of the inter-vehicle distance. Then, when the mode is “short” or “long”, the traveling control unit 5 sets the target tracking distance Dtrg according to the vehicle speed V using the corresponding map, and when the mode is “medium”. Sets an intermediate value between values calculated when the mode is “short” and “long” as the tracking target distance Dtrg. The travel control unit 5 calculates, for example, a distance deviation ΔD (= Dtrg−D) between the follow target distance Dtrg and the inter-vehicle distance D, and a relative speed Vfrel (= Vf) between the preceding vehicle speed Vf and the own vehicle speed V. -V) is calculated, and the target acceleration a2 is calculated with reference to a map or the like set in advance using these as parameters.

  The traveling control unit 5 sets the target acceleration a1 as a basic target acceleration (hereinafter referred to as a basic target acceleration) a0 during constant speed traveling control, and out of the target accelerations a1 and a2 during follow-up traveling control. Is set as the basic target acceleration a0, that is, the travel control unit 5 is based on the relationship between the actual vehicle speed (own vehicle speed V) and the target vehicle speed (set vehicle speed Vset or preceding vehicle speed Vf). The target acceleration a0 is calculated. The traveling control unit 5 basically sets the calculated basic target acceleration a0 as the final target acceleration a.

  When the target acceleration a is set, the traveling control unit 5 performs an opening control (engine output control) of the electronic control throttle valve 17 through the E / G_ECU 7, thereby generating an acceleration corresponding to the target acceleration a. That is, for example, the current gear ratio i is input from the T / M_ECU 9 and the road gradient θ detected by the gradient sensor 21 is input to the E / G_ECU 7. Then, for example, the E / G_ECU 7 corrects the target acceleration a with the road gradient θ, and refers to a preset map or the like based on the corrected target acceleration a and the current gear ratio i, etc. Is calculated. Then, the E / G_ECU 7 performs engine output control through opening control of the throttle valve 17 based on the calculated target throttle opening.

  Further, when the traveling control unit 5 determines that sufficient acceleration (deceleration) cannot be obtained only by engine output control, the traveling control unit 5 performs output hydraulic pressure control (automatic brake control) from the brake booster 18 through the BRK_ECU 8. By doing so, a braking force is generated.

  Further, during the execution of such ACC, the T / M_ECU 9 basically performs automatic gear shifting with reference to a preset basic shift map or the like based on, for example, the vehicle speed V and the throttle opening of the engine. The gear ratio i of the machine (not shown) is controlled. On the other hand, the T / M_ECU 9 stores a shift map and the like for traveling on a slope road in advance, and the T / M_ECU 9 detects the vehicle based on the road slope θ detected by the slope sensor 21 or the like, for example. When it is determined that the traveling road is a slope road (an uphill slope or a downward slope road) that is equal to or greater than a predetermined road, a speed change ratio i is appropriately set to a basic speed map or the like with reference to a speed change map for the slope road or the like. Forcibly downshift to a speed ratio lower than the set speed ratio.

  Here, for example, as a countermeasure against a case where the forced downshift control on the gradient road is not performed due to a decrease in the detection accuracy of the gradient sensor 21, the traveling control unit 5 performs automatic braking intervention via the BRK_ECU 8. When it is determined that the control has continued for a preset time t0 (for example, t0 = 5 s), interrupt control for setting the target acceleration a is performed. That is, in the present embodiment, the traveling control unit 5 changes the target acceleration a to a preset negative side set value B (for example, B = −0.03 G). Then, the traveling control unit 5 maintains the changed target acceleration a until the basic target acceleration a0 exceeds a positive set value a0th (for example, a0th = 0.015G) by deceleration based on the target acceleration a.

  Then, when the host vehicle speed V decreases according to the target acceleration a set by the interrupt control and the basic target acceleration a0 exceeds the set value a0th, the traveling control unit 5 thereafter sets the preset time t1 (for example, , T1 = 3 s) or more, the execution of the engine output control and the automatic intervention control of the brake is prohibited. In this period, the self-control after the interrupt control is performed especially by the active acceleration by the engine output control. A sudden change in the vehicle speed V is suppressed. However, the traveling control unit 5 determines that the basic target acceleration a0 is out of a preset range due to a change in the road gradient θ or acceleration / deceleration of the preceding vehicle (for example, a range of −0.04G ≦ a0 ≦ 0.025G). ), Cancel the prohibition of engine output control and brake automatic intervention control.

  Thus, in this embodiment, the traveling control unit 5 implements each function as a target acceleration setting unit and an interrupt control unit. Moreover, the traveling control unit 5 realizes a function as an engine control means together with the E / G_ECU 7 and realizes a function as a brake control means together with the BRK_ECU 8.

  Next, calculation of the target acceleration executed in the traveling control unit 5 during execution of ACC will be described according to the flowchart of the target acceleration calculation routine shown in FIG. This routine is repeatedly executed every set time. When the routine starts, the traveling control unit 5 first calculates the basic target acceleration a0 in step S101. That is, the traveling control unit 5 calculates a target acceleration a1 according to the vehicle speed deviation Vsrel between the host vehicle speed V and the set vehicle speed Vset and the host vehicle speed V during constant speed traveling without capturing the preceding vehicle, and this target acceleration. a1 is set as the basic target acceleration a0. On the other hand, during the follow-up traveling while capturing the preceding vehicle, the traveling control unit 5 calculates the target acceleration a1 as described above, the distance deviation ΔD between the inter-vehicle distance D with the preceding vehicle and the following target distance Dtrg, and the preceding vehicle. A target acceleration a2 is calculated based on the speed Vf and the relative speed Vfrel of the host vehicle speed V, and any one of these target accelerations a1 and a2 is set as the basic target acceleration a0.

  When the process proceeds from step S101 to step S102, the traveling control unit 5 determines whether or not the interrupt flag F1 indicating that the start of the interrupt control for the calculation of the final target acceleration a has been determined is “1”. If it is set to “1”, the process proceeds to step S103, and if it is reset to “0”, the process proceeds to step S105.

  When the process proceeds from step S102 to step S103, the traveling control unit 5 checks whether or not the brake automatic intervention control through the BRK_ECU 8 continues for a set time t0 (for example, t0 = 5 s).

  If it is determined in step S103 that the brake automatic intervention control has not continued for the set time t0 or longer, the traveling control unit 5 proceeds to step S104.

  On the other hand, when it is determined in step S103 that the automatic intervention control of the brake has continued for the set time t0 or longer, the traveling control unit 5 proceeds to step S104, sets the interrupt flag F1 to “1”, and then proceeds to step S104. The process proceeds to S107.

  When the process proceeds from step S102 to step S105, the traveling control unit 5 checks whether or not a prohibition flag F2 for prohibiting engine output control and brake automatic intervention control is set to "1", and prohibition flag F2 When “1” is set to “1”, the process proceeds to step S109, and when the prohibition flag F2 is reset to “0”, the process proceeds to step S106.

  When the process proceeds from step S105 to step S106, the traveling control unit 5 checks whether or not the basic target acceleration a0 is greater than or equal to the set value a0th. If it is less than the set value a0th, the process proceeds to step S107.

  And if it progresses to step S107 from step S104 or step S106, the traveling control unit 5 will calculate the target acceleration a by interruption control, and will progress to step S112. That is, in step S107, the traveling control unit 5 sets, for example, a preset negative side set value B (for example, B = −0.03G) as a final value, and uses a known filter process or the like. An operation for converging the target acceleration a to the final value B is performed (see FIG. 3).

  On the other hand, when it is determined in step S106 that the basic target acceleration a0 is equal to or greater than the set value a0th, the traveling control unit 5 determines the end of the interrupt control, proceeds to step S108, and sets the prohibition flag F2 to “1”. After setting, the process proceeds to step S109.

  If it progresses to step S109 from step S105 or step S108, the traveling control unit 5 will check whether the elapsed time after complete | finishing interruption control is more than the setting time t2.

  If the traveling control unit 5 determines in step S109 that the elapsed time since the end of the interrupt control is equal to or longer than the set time t2, the travel control unit 5 proceeds to step S111, and the elapsed time is less than the set time t2. If it is determined, the process proceeds to step S110.

  When the process proceeds from step S109 to step S110, the traveling control unit 5 determines whether or not the current basic target acceleration a0 is within a preset range (for example, within a range of −0.04G ≦ a0 ≦ 0.025G). If it is determined that the current value is within the set range, the process proceeds to step S112. If it is determined that the current value is outside the set range, the process proceeds to step S111.

  Then, when the process proceeds from step S109 or step S110 to step S111, the traveling control unit 5 resets the interrupt flag F1 to “0”, resets the prohibition flag F2 to “0”, and then proceeds to step S112.

  When the process proceeds from step S103, step S107, step S110, or step S111 to step S112, the traveling control unit 5 checks whether or not the target acceleration a by the interrupt control is currently calculated, and is currently performing the interrupt control. If it is determined in step S107 that the target acceleration a has been calculated, the routine is directly exited.

  On the other hand, when it is determined in step S112 that the current interruption control is not being performed and the target acceleration a is not calculated, the traveling control unit 5 proceeds to step S113, and the previous target acceleration a (n-1) and the basic acceleration are calculated. It is checked whether or not the target acceleration a (n-1) matches.

  If it is determined in step S113 that the previous target acceleration a (n-1) and the basic target acceleration a (n-1) do not match due to the intervention of interrupt control, the traveling control unit 5 Proceeding to step S114, for example, using a known filter process or the like to perform an operation for converging the target acceleration a to the basic target acceleration a0, and then exits the routine.

  On the other hand, when it is determined in step S113 that the previous target acceleration a (n-1) and the basic target acceleration a (n-1) match, the traveling control unit 5 proceeds to step S115, and the basic target acceleration a (n-1) is determined. After setting the acceleration a0 as the target acceleration a, the routine is exited.

  According to such an embodiment, when it is determined that the automatic intervention control of the brake has continued for the set time t0 or more during execution of the ACC, the target acceleration a is changed to the preset negative value B, and the change is made. By performing the interrupt control for maintaining the target acceleration a until the basic target acceleration a0 exceeds the positive set value a0th, it is relatively caused by the detection error of the road gradient θ by the gradient sensor 21 and the like. Even when a forced downshift of the transmission on a gentle slope road is not performed, automatic braking intervention with a weak braking force (for example, a braking force weaker than −0.03G) is continued for a long time. Therefore, it is possible to perform good vehicle speed control without performing it automatically. For example, when the host vehicle 1 is controlled at a vehicle speed of 60 Km / h, the vehicle speed V on the low speed side that does not cause the driver to feel uncomfortable by calculating the target acceleration a by interrupt control (for example, To 55 km / h), the automatic intervention time of the brake and the intervention frequency can be reduced accordingly.

  In this case, the execution of engine output control through the E / G_ECU 7 and the automatic intervention control of the brake through the BRK_ECU 8 are prohibited until a set time t1 (for example, t1 = 3 s) after execution of the interrupt control elapses. As a result, aggressive acceleration due to engine output control can be suppressed, and the brake non-intervention time can be ensured accurately. On the other hand, even if the elapsed time after the interrupt control is less than the set time t1, the basic target acceleration a0 is outside the preset range (for example, outside the range of −0.04G ≦ a ≦ 0.025G). Then, by canceling the prohibition of the engine output control and the automatic intervention control of the brake, it is possible to realize the vehicle speed control that accurately copes with the change in the road gradient and the acceleration / deceleration of the preceding vehicle.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention.

1 ... Vehicle (own vehicle)
2 ... Driving support device 2a ... Stereo camera assembly 3 ... Stereo camera 4 ... Stereo image recognition device 5 ... Travel control unit (target acceleration setting means, engine control means, brake control means, interrupt control means)
7 ... Engine control unit (engine control means)
8 ... Brake control unit (brake control means)
DESCRIPTION OF SYMBOLS 9 ... Transmission control unit 15 ... Cruise control switch 17 ... Electronically controlled throttle valve 18 ... Brake booster 21 ... Gradient sensor

Claims (3)

A target acceleration setting means for calculating a basic target acceleration based on the relationship between the actual vehicle speed and the target vehicle speed, and setting the target acceleration based on the basic target acceleration;
Engine control means for performing engine output control through throttle valve opening control based on the target acceleration;
Brake control means for generating a braking force by automatic intervention control of a brake when the engine output control alone cannot obtain sufficient deceleration with respect to the target acceleration set to the negative side, A device,
When it is determined that the automatic intervention control of the brake has continued for a preset time or longer, the target acceleration is changed to a preset negative value, and the target deceleration is set to the positive target acceleration. A vehicle driving support device comprising an interrupt control means for performing an interrupt control that is maintained until a set value is exceeded.   The interrupt control means prohibits engine output control by the engine control means and automatic brake control by the brake control means until a set time elapses after execution of the interrupt control. The vehicle driving support device according to claim 1.   Even if the set time after execution of the interrupt control does not elapse, the interrupt control means is configured to control engine output and brake by the engine control means when the basic target acceleration is outside the set range. 3. The vehicle driving support apparatus according to claim 2, wherein the prohibition of the automatic intervention control of the brake by the control means is canceled.

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