JP6539307B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a control device of a vehicle and a travel control system of the vehicle.

    BACKGROUND ART Conventionally, there has been developed a system for operating a braking actuator to avoid a collision when it is determined that an obstacle in front of the vehicle is recognized by an external world recognition device such as a stereo camera and the vehicle collides. Patent Document 1 discloses a technique for obtaining a realized course collision probability from the predicted course of another vehicle and the realized course of the host vehicle, and calculating the degree of risk of the driver based on the realized course collision probability.

JP 2008-250492 A

     For example, when an obstacle such as a pedestrian or another vehicle jumps into the traveling path of the own vehicle, it is difficult to detect a collision sufficiently in advance, and the future position is estimated from the movement of the obstacle and the collision Predict the possibility of However, since it is prediction to the last, when the braking control is performed based on the prediction information, the braking control is executed even though the obstacle does not arrive on the traveling road of the vehicle by actually stopping immediately before etc. If such an operation is repeated frequently, the driver may feel uncomfortable. On the other hand, if the braking control start timing is delayed or the braking control start determination criterion is changed in order not to give a sense of incongruity to the driver, the effect may be lowered even when the braking control is truly necessary.

  The present invention has been made in view of the above-described point, and an object thereof is to obtain a control device of a vehicle capable of more highly safe traveling control without giving a sense of discomfort to a driver. .

    A control device of a vehicle according to the present invention for solving the above problems includes: collision risk calculation means for calculating a collision risk that the vehicle collides with an obstacle based on the external world recognition information of the external world recognition device; And driving characteristics changing means for changing the driving characteristics of the driving device accordingly.

    According to the present invention, since the drive characteristic of the drive device is changed when the collision risk is high, for example, when there is a danger of a collision, when the driver depresses the accelerator, the driving force is changed. By lowering it, the vehicle can be controlled in the safe direction. The problems, configurations, and effects other than those described above will be clarified by the following description of the embodiment.

The functional block diagram of a traveling control system. The figure which shows an example of a structure of a control apparatus. The figure which shows an example of a structure of a control apparatus. FIG. 2 is a functional block diagram of a control device. The flowchart explaining an example of the traveling control method. The figure which shows the control content performed according to the time change of collision risk. The figure which shows the change of the vehicle speed by drive characteristic change control. The figure which shows the relationship between collision danger degree and the gain of a torque command value. The figure which shows an example of the relationship between the accelerator opening in a certain motor rotation speed, and a torque command value. The figure which shows an example of the relationship between the accelerator opening in a certain motor rotation speed, and a torque command value. The figure explaining the relationship between the motor rotation speed for every throttle opening, and a torque command value. The figure which shows presence probability distribution in which an obstacle (pedestrian) exists on the advancing path of the own vehicle. The flowchart explaining the method to calculate the position after fixed time progress of an obstacle. The schematic diagram in case a pedestrian and other vehicles exist ahead of self-vehicles.

    Next, embodiments of the present invention will be described in detail with reference to the drawings. In the traveling control system 1 of the present embodiment, for example, as shown in FIG. 14, an obstacle 301 such as a pedestrian 301 b or another vehicle 301 a may jump out to a predicted traveling path 202 of the own vehicle 201 and collide with the own vehicle 201. In the predicted situation, the collision risk with the obstacle 301 is calculated based on the external world recognition information from the external world recognition sensor. Then, compared with the first threshold and the second threshold, drive characteristic change control is performed when the collision risk is greater than the first threshold, and braking control is performed when the collision risk is greater than or equal to the second threshold.

    FIG. 1 is a functional block diagram of a traveling control system. The traveling control system 1 is a system that controls traveling of the host vehicle 201 (see FIG. 14), and includes a control device 101, a driving device 102, and a braking device 103. The host vehicle 201 is an electric car. The control device 101 has a motor controller, and the drive device 102 has a motor for traveling the vehicle. The braking device 103 has a braking actuator.

     The control device 101 controls the drive device 102 and the braking device 103 based on the vehicle speed, the accelerator opening degree, the external world recognition information, and the like. The vehicle speed information is acquired from the vehicle speed sensor, and the information on the accelerator opening degree is acquired from the accelerator opening degree sensor provided on the accelerator pedal. The external world recognition information is acquired from the external world recognition sensor mounted on the host vehicle 201, the operation state of an on-vehicle device such as a wiper device, a headlight, and the like. The external world recognition information includes relative position with respect to the obstacle 301 located in front of the host vehicle 201 and a relative velocity vector, and further includes information such as light and dark around the vehicle, weather, road surface condition and the like. May be

  The external world recognition sensor has a stereo camera. The stereo camera captures the front of the host vehicle 201 with the left and right cameras, calculates the relative position of the obstacle 301 and the relative velocity vector from the parallax of the left and right images, and outputs it to the control device 101 as external world recognition information. By using a stereo camera as the external world recognition sensor, accurate external world recognition information can be acquired with a simple configuration. A combination of a monocular camera and a millimeter wave radar may be used instead of the stereo camera. 2 and 3 show an example of the configuration of the control device, and FIG. 4 is a functional block diagram of the control device.

    As shown in FIG. 2, the control device 101 may be configured by two modules of an advanced data assistance system (ADAS) 111 and a VCM (vehicle control module) 121, and as shown in FIG. 3. , And may be configured by one module of the VCM 121. The ADAS 111 has a torque command value calculation means 112 and a collision risk degree calculation means 113, and the VCM 121 has a motor control means 122.

    The torque command value calculation means 112 calculates a torque command value (requested driving force) based on the information of the vehicle speed and the accelerator opening as shown in FIG. The collision risk calculation means 113 calculates the collision risk and outputs a gain according to the collision risk. Then, the final torque command value (target driving force) calculated using the torque command value and the gain is output to the motor control means 122. The motor control means 122 outputs a current command value corresponding to the final torque command value to the drive device 102. The drive device 102 drives the motor by the current command value.

    FIG. 5 is a flowchart illustrating a travel control method by the travel control system. First, in step S101, processing for acquiring external world recognition information is performed, and then, in step S102, processing for calculating a collision risk is performed. The collision risk (%) is a value indicating the possibility that the obstacle 301 collides with the host vehicle 201, and is calculated based on the predicted travel path 202 of the host vehicle 201 and the external world recognition information. It may be corrected according to the external environment such as the road surface condition. The collision risk can be calculated, for example, using a known method described in JP-A-2010-250501. A specific calculation method of the collision risk in the present embodiment will be described later.

  Then, in step S103, it is determined whether the collision risk is greater than a preset first threshold (D1), and in the case where the first threshold (D1) or less (no), the obstacle 301 is the host vehicle. It is determined that the risk of colliding with 201 is low, and the process is ended (End). Therefore, drive characteristic change control is not performed, and normal control is performed. In normal control, the value of the gain for adjusting the torque command value is 1.0, and the torque command value calculated by the torque command value calculation means 112 is output to the motor control means 122 as the final torque command value as it is. . Thereby, the torque according to the accelerator opening is output from the motor.

    On the other hand, if the collision risk is greater than the first threshold (D1) (Yes), it is determined that the risk of the obstacle 301 colliding with the host vehicle 201 is high, and the process proceeds to step S104. In step S104, it is determined whether the collision risk is larger than a second threshold (D2) set in advance, in order to select which of the braking control and the drive characteristic change control is to be performed according to the collision risk. Be done. The second threshold (D2) has a value larger than the first threshold (D1) (D2> D1).

    When the collision risk is smaller than the second threshold (D2) (no), the process shifts to step S105 to perform drive characteristic change control. In the drive characteristic change control, processing for changing the drive characteristic is performed by changing the target drive force to be transmitted to the drive device 102 (drive characteristic change means). Specifically, control is performed to weaken the acceleration response by reducing the final torque command value (target driving force) according to the degree of accelerator opening than in normal times.

Therefore, for example, in a situation where the collision risk is between the first threshold (D1) and the second threshold (D2), the driving force decreases even if the driver continues to depress the accelerator pedal, and the acceleration of the host vehicle 201 is suppressed. Therefore, when the collision risk is further increased after that and the braking control is carried out exceeding the second threshold (D2), the effect of collision avoidance and collision damage reduction is obtained (because the vehicle speed is suppressed low). It will be easier.
Further, even if the collision risk level subsequently decreases, the driver is less likely to feel discomfort compared to the case where the braking control is performed at this stage. In particular, since the motor used in drive device 102 of host vehicle 201 in the present embodiment can adjust the output torque linearly as compared with the internal combustion engine, the final torque command according to the accelerator opening ( It is possible to control to reduce the target driving force smoothly and to weaken the acceleration response smoothly, and to control in the safe direction without giving a sense of discomfort to the driver.

    On the other hand, if the collision risk is greater than the second threshold (D2) (Yes) in step S104, it is determined that the collision risk is particularly high, and the process proceeds to step S106 to perform braking control. The braking control can be performed in the same manner as in the prior art. First, an alarm or the like is blown into the passenger compartment to warn the driver (alarm sounding), and then the braking actuator 103 of the braking device 103 is controlled. .

    FIG. 6 is a view showing control contents executed according to a time change of collision risk, and FIG. 7 is a view showing change of vehicle speed when drive characteristic change control is performed and when it is not performed. .

    For example, when the driver depresses the accelerator pedal, the vehicle speed rises with a constant inclination, and as shown in FIG. 14, another vehicle 301a is in front of the host vehicle 201, and as shown in FIG. Conventionally, when the degree rises with the passage of time, the vehicle speed rises with the same inclination as shown by a two-dot chain line in FIG. On the other hand, according to the vehicle travel control system of the present invention, when the collision risk exceeds the first threshold (D1), the drive characteristic change control is executed, and as shown by the solid line in FIG. It becomes loose (it becomes difficult to accelerate). Then, when the collision risk exceeds the second threshold (D2), the braking control is performed, and the deceleration is performed at a predetermined deceleration. Therefore, collision damage can be reduced and safety can be controlled.

  FIG. 8 is a diagram showing the relationship between the collision risk and the gain of the torque command value. As shown by the broken line L1 in FIG. 8, the collision risk and gain are gradually graded with a constant slope as the collision risk increases between the first threshold (D1) and the second threshold (D2). It may be set to decrease, and as shown by the solid line L2 in FIG. 8, when the collision risk is low, the degree of decrease in gain is small, but as the degree of collision risk becomes high, the degree of gain decrease It may be set to decrease exponentially so that increases rapidly.

    In the case where the gain is set to gradually decrease at a constant slope (L1), the torque command value is linearly decreased, which makes it possible to control the vehicle more safely. On the other hand, in the case where the gain decreases with a quadratic slope (L2), when the collision risk is close to the first threshold (D1), the possibility of collision is not so high either, so the torque command value The amount of adjustment by the gain of is very small, and the same torque as normal is output. Therefore, it is possible to prevent the torque command from being greatly reduced and giving the driver a sense of discomfort. Then, when the collision risk is close to the second threshold (D2), the possibility of a collision is high, so the adjustment amount by the gain of the torque command value is made extremely large, and the final torque command value (target The driving force is greatly reduced to weaken the acceleration response.

     FIGS. 9 and 10 are diagrams showing the relationship between the torque command value and the accelerator opening degree at a certain motor rotational speed, and FIG. 11 is a diagram showing the relationship between the motor torque and the motor rotational speed for each accelerator opening.

    In the drive characteristic change control according to the present embodiment, as shown in FIGS. 9 and 10, the collision danger is achieved by adjusting the gain of the torque command as described above at the same accelerator opening P1 at a certain motor rotational speed. The drive characteristic is changed so as to decrease the final torque command value (target driving force) as compared with the smaller one.

    The collision risk is divided into a plurality of stages according to the size, and in this embodiment, it is divided into small, medium, and large. The drive characteristics may be changed so as to gradually increase the amount by which the torque command value is reduced as the collision risk increases, and may also be changed so as to increase quadratically.

    As shown in FIG. 11, for example, when the accelerator opening degree P1 and the motor rotational speed ω1 are used, the torque command value is usually To, but in the present embodiment, the value differs depending on the collision risk. It is adjusted to Ts when the degree of risk is small, Tm when it is medium, and Tb when it is large (however, Ts> Tm> Tb).

    As shown in FIG. 9, when adjusting the final torque command at equal intervals in the order of small to large collision risks, the gain is set as shown by a broken line L1 in FIG. Further, as shown in FIG. 10, when adjusting the final torque command so that the intervals become gradually larger in the order from small to large as shown in FIG. 10, the gain is set as shown by solid line L2 in FIG.

Next, a specific example of calculating the collision risk in the present embodiment will be described. The collision risk can be calculated based on, for example, the predicted travel path of the host vehicle 201, the current position of the obstacle, and the position of the obstacle after a predetermined time has elapsed. In this embodiment, the action prediction of the obstacle is performed based on the current position of the obstacle and the position after a predetermined time, and the obstacle existence probability is calculated from the action prediction and the predicted traveling path of the vehicle 201. . Then, the collision risk is calculated by dividing the obstacle existence probability by TTC (collision prediction time) .

    The collision risk degree calculation means 113 calculates means for calculating a predicted traveling path of the host vehicle 201, means for detecting the current position of an obstacle such as a pedestrian or another vehicle, and the position of the obstacle after a predetermined time has elapsed. Means for

    The predicted travel path of the host vehicle 201 can be predicted by a stereo camera that is an external world recognition sensor. The stereo camera can recognize the white line of the traveling lane based on the image obtained by imaging the front of the host vehicle 201. Therefore, usually, the trajectory along the traveling lane is predicted, and the traveling route is predicted based on the trajectory. Also, if there is no white line in the traveling lane, or if the host vehicle 201 clearly deviates from the lane, the trajectory is predicted by calculating the behavior of the host vehicle from the vehicle speed, yaw rate and steering angle of the host vehicle 201, The traveling route is predicted based on the locus.

    The determination of the current position of the obstacle, and whether the obstacle is a pedestrian or a vehicle can be detected by a stereo camera that is an external world recognition sensor. Various detection methods are known, and these techniques can be used.

    FIG. 12 is a diagram showing an existing probability distribution in which an obstacle (pedestrian) is present on the traveling path of the vehicle. The driver, as shown in FIG. 12, determines that the pedestrian 301b moving toward the traveling path of the host vehicle 201 from the sideways may be jumping out on the traveling path if the speed is high, and traveling is slow if it is late We are predicting behavior to judge that it will stop in front of the road (cognitive judgment). The collision risk calculation means 113 performs the same process as the driver's action prediction by obtaining an existing probability that an obstacle is estimated to be present after t seconds.

    When the driver determines that the collision risk is higher than a certain level as a result of the above-described recognition determination, the driver first releases the accelerator or releases the foot from the accelerator pedal and places the foot on the brake pedal. Then, when the obstacle really pops out, the brake pedal is depressed to perform braking. That is, the accelerator response is changed according to the collision risk degree, the state is observed, and then the brake operation is performed. The traveling control system 1 performs the same processing as the operation of the driver by the drive characteristic change control and the braking control.

    FIG. 13 is a flowchart illustrating a method of calculating the position of an obstacle after a predetermined time has elapsed, and FIG. 14 is a diagram illustrating a method of calculating a state amount.

    In step S121, first, an obstacle to be controlled is detected from the captured image, and the relative position, velocity, and acceleration of the obstacle are calculated.

    In step S122, estimation processing of the current state quantity by the Kalman filter is performed. This makes it possible to estimate the current state quantities of pedestrians and other vehicles (obstacles) in consideration of errors in detection results. The state quantities include the relative position, velocity, and acceleration of the obstacle.

    In step S123, the movement of the obstacle follows the equation of motion (considering acceleration), and processing for predicting the position after TTC is performed. Since the current state quantity is stabilized by the Kalman filter, it is possible to estimate the future state quantity more stably.

    Then, in step S124, position information of the past n frames is stored, and in step S125, a process of generating a presence probability distribution after TTC from the future future position estimation information is performed.

    Then, in step S126, processing is performed to represent the distribution as a normal distribution having the variance of the past future position estimation positions. More flexible control is possible by determining the existence probability. Then, erroneous estimation suppression processing is performed using various conditions. For example, if there is a guardrail between the vehicle and a pedestrian, it is difficult for the pedestrian to jump out on the road, or if it has a high speed in the front-rear direction (the direction of travel of the vehicle) The process of suppressing erroneous estimation is performed using the condition that it is difficult to make such movements.

    When the collision risk is greater than the first threshold (D1) and smaller than the second threshold, the traveling control system 1 of the present invention executes drive characteristic change control for changing the responsiveness of the drive device to the accelerator opening degree. Reduce the corresponding torque command (required driving force). Then, braking control is performed when the collision risk is greater than the second threshold (D2). Therefore, first, the acceleration response is weakened, and then the braking control is executed. Therefore, as shown in FIG. 14, the pedestrian 301b jumps out in front of the own vehicle 201, and the other vehicle 301a suddenly If you break in, you can reduce collision damage and control in a safer direction.

    In the embodiment described above, the drive characteristic change control and the braking control are performed using the same reference as the collision risk, but for example, the collision risk is used as a determination criterion for the drive characteristic change control. For control, the conventional TTC may be used as a criterion. In such a configuration, the drive characteristic change control may be simply added to the existing configuration for performing the braking control, and the configuration can be easily introduced.

  In the above embodiment, although the case where the host vehicle 201 is an electric vehicle and control for changing the drive characteristic of a motor is described as an example, the host vehicle 201 is an automobile including an internal combustion engine, and the internal combustion engine The present invention can also be applied to those that change the drive characteristics of

    As mentioned above, although the embodiment of the present invention was explained in full detail, the present invention is not limited to the above-mentioned embodiment, and various designs are possible in the range which does not deviate from the spirit of the present invention described in the claim. It is possible to make changes. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to one having all the described configurations. Further, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, with respect to a part of the configuration of each embodiment, it is possible to add / delete / replace other configurations.

1 · · · Drive control system 101 · · · Control device 102 · · · Drive device 112 · · · torque command value calculation means 113 · · · collision risk degree calculation means 122 · · · motor control means 201 · · · own vehicle 202 ··· Predicted traveling path 301 ··· Obstacle 301 a ··· Other vehicle 301 b ··· Pedestrian

Claims (4)

Collision risk calculation means for calculating the collision risk of the own vehicle colliding with an obstacle based on the external world recognition information acquired from the external world recognition device;
Drive characteristic change means for changing the drive characteristic of the internal combustion engine drive device according to the collision risk;
The driving characteristic changing means is configured to increase a gain of a torque command value according to an accelerator opening degree from a positive first gain to a positive second gain when the collision risk is larger than a preset first threshold. Change to
The second gain is smaller than the first gain,
The drive characteristic is changed such that the amount of reduction of the gain is larger than the smaller one of the larger the collision risk.
The drive characteristic changing means changes the drive characteristic in at least one of a first mode and a second mode,
The first mode is a mode in which the drive characteristic is changed such that the amount by which the gain is reduced gradually increases as the collision risk increases.
Wherein the second mode, the drive characteristics, Oh Ri mode where the amount of reducing the gain in accordance with the collision risk is increased is changed to increase quadratically, further,
A collision risk calculation unit configured to calculate the collision risk by using the obstacle existence probability and the collision prediction time;
The collision risk calculation unit
The present state quantity of the obstacle is estimated, and the presence probability distribution of the obstacle after the collision prediction time has elapsed is obtained from the result of the estimation process,
A control apparatus for a vehicle , comprising performing erroneous estimation suppression processing on the presence probability distribution . In the control device of a vehicle according to claim 1,
The collision risk calculation unit cormorants row the estimation process by using a Kalman filter, that the control device for a vehicle according to claim.   In the control device for a vehicle according to claim 1 or 2,
  The control device for a vehicle according to claim 1, wherein the erroneous estimation suppression process reflects the condition that the pedestrian is unlikely to jump out on a road when there is a guardrail between the pedestrian and the host vehicle.   In the control device for a vehicle according to claim 1 or 2,
  The control device for a vehicle according to claim 1, wherein the erroneous estimation suppression process reflects the condition that the vehicle is unlikely to move in the vehicle width direction when the velocity of the vehicle is faster than a predetermined velocity.

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