JP2015047045A - Drive support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive support device which can properly perform automatic stop of a vehicle in a constitution using an ultrasonic sensor.SOLUTION: When an obstacle present in detection regions of ultrasonic sensors SO1, SO2, SO3 and SO4 is detected and there is a possibility of collision between the obstacle and a vehicle 1, control for actuating automatic brake and regeneration brake is started. Brake force of the automatic brake is brake force from the operation of a brake 15 and generated with hydraulic pressure. Therefore, time lag is generated between the output of an operation request of the automatic brake and rise-up of the brake force of the automatic brake to target brake force. On the other hand, brake force of the regeneration brake is raised quickly since it is generated from electrical control of a motor 11. Therefore, shortage of the brake force of the automatic brake can be compensated by the brake force of the regeneration brake.

Description

  The present invention relates to a driving support device mounted on a vehicle.

  2. Description of the Related Art Conventionally, a driving assistance device that is mounted on a vehicle such as an automobile and automatically stops the vehicle before an obstacle with a possibility of collision is known. In the driving assistance device, for example, the distance from the vehicle to the obstacle is detected by a millimeter wave radar, a laser radar, or a camera, and based on this distance and the relative speed between the vehicle and the obstacle, a collision prediction time (TTC: Time To Collision) is calculated. When the collision prediction time reaches a predetermined time and the possibility of collision between the vehicle and the obstacle increases, an automatic brake operation request is generated and the automatic brake is operated.

  On the other hand, as an obstacle detection device mounted on a vehicle, there is one using a plurality of ultrasonic sensors (sonar). In this obstacle detection device, for example, a plurality of ultrasonic sensors are turned on in a predetermined order, and ultrasonic waves are transmitted from the turned-on ultrasonic sensors. If there is an obstacle within the reach of ultrasonic waves from each ultrasonic sensor, the ultrasonic wave hits the obstacle and is reflected, and the reflected ultrasonic wave (reflected wave) is received by the ultrasonic sensor. When the ultrasonic sensor receives the reflected wave, the distance from the vehicle to the obstacle is calculated based on the time from transmission of the ultrasonic wave to reception.

JP 2012-131312 A JP 2004-45320 A

  Ultrasonic sensors are less expensive than millimeter wave radars, laser radars, and cameras. Therefore, the inventors of the present application have considered reducing the cost of the driving support device by adopting an obstacle detection device using an ultrasonic sensor in the driving support device.

  However, the ultrasonic sensor has an extremely short distance at which an obstacle can be detected as compared with a millimeter wave radar, a laser radar, and a camera. Therefore, when an obstacle is detected by an obstacle detection device using an ultrasonic sensor, if the distance between the vehicle and the obstacle is short and the start of the braking force by the automatic brake is delayed, the vehicle is more likely to be an obstacle. It approaches.

  An object of the present invention is to provide a driving support device that can automatically and successfully stop a vehicle in a configuration using an ultrasonic sensor.

  In order to achieve the above object, a driving support apparatus according to the present invention is a driving support apparatus mounted on a vehicle, and operates an ultrasonic sensor to detect a detection area (an obstacle can be detected) of the ultrasonic sensor. The vehicle's service brake (service brake) is activated when there is a possibility that the vehicle will collide with an obstacle detected by the obstacle detection means. A request output means for outputting a request, an automatic brake means for operating a service brake in response to a request output by the request output means, and from a request output by the request output means until the braking force of the service brake rises to a target braking force And a regenerative brake means for operating a regenerative brake by operating a vehicle driving motor as a generator.

  According to this configuration, when an obstacle existing in the detection area of the ultrasonic sensor is detected and there is a possibility that the obstacle and the vehicle collide, a request for operating the service brake of the vehicle is output. In response to the output of this request, control for operating the service brake and the regenerative brake is started.

  Since the braking force of the service brake is generated by hydraulic pressure (hydraulic pressure) or pneumatic pressure, a time lag occurs from the output of the service brake operation request until the braking force of the service brake rises to the target braking force. On the other hand, the braking force of the regenerative brake is generated by electrical control of the traveling motor, so that its rise is quick. Therefore, the shortage of the braking force of the service brake can be compensated by the braking force of the regenerative brake until the braking force of the service brake rises to the target braking force after the output of the service brake operation request. As a result, since a sufficient braking force can be applied to the vehicle immediately after the service brake operation request is output, the vehicle can be automatically stopped as expected.

  The detection area of the ultrasonic sensor is a relatively short distance area. Therefore, when an obstacle is detected, the vehicle and the obstacle are close to each other. However, according to the present invention, the vehicle can be automatically stopped well, so that the vehicle can be compared with the millimeter wave radar, the laser radar, and the camera. By using an inexpensive ultrasonic sensor, it is possible to avoid the collision between the vehicle and the obstacle or reduce the damage caused by the collision while reducing the cost.

1 is a schematic plan view of a vehicle equipped with a driving support apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure for control of each part of a vehicle. It is a flowchart which shows the flow of automatic brake control. It is a figure which shows the time change of the braking force of a regenerative brake, the braking force of an automatic brake, and the resultant force of those braking forces.

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

  FIG. 1 is a schematic plan view of a vehicle 1 equipped with a driving support apparatus according to an embodiment of the present invention.

  The vehicle 1 is a small electric vehicle, and is, for example, a city commuter used for traveling in an urban area such as moving in a city or commuting from a nearby area.

  The vehicle 1 includes a vehicle body 2. A vehicle compartment 3 is formed in the vehicle body 2. In the passenger compartment 3, a front seat (driver's seat) 4 and a rear seat 5 are provided side by side.

  Front wheels 6 </ b> L and 6 </ b> R are provided on the left front portion and the right front portion of the vehicle body 2, respectively. The front wheels 6 </ b> L and 6 </ b> R are steering wheels that are steered to change the traveling direction of the vehicle 1.

  Rear wheels 7L and 7R are provided at the left rear portion and the right rear portion of the vehicle body 2, respectively. The rear wheels 7L and 7R are driving wheels to which driving force for traveling the vehicle 1 is input.

  In addition, ultrasonic sensors (sonar) SO1, SO2, SO3, SO4 are disposed on the right front portion, left front portion, left rear portion, and right rear portion of the vehicle body 2, respectively. The ultrasonic sensors SO1 and SO2 transmit ultrasonic waves toward the front of the vehicle 1 and receive an ultrasonic wave (reflected wave) reflected by the obstacle when there is an obstacle in the detection area ahead of the vehicle. . The ultrasonic sensors SO3 and SO4 transmit ultrasonic waves toward the rear of the vehicle 1 and receive an ultrasonic wave (reflected wave) reflected by the obstacle when there is an obstacle in the detection area behind the vehicle. .

  FIG. 2 is a block diagram showing a configuration for controlling each part of the vehicle 1.

  The vehicle 1 is provided with a motor 11 that generates a driving force for traveling. The motor 11 is disposed, for example, at the rear end portion of the vehicle body 2. The driving force generated by the motor 11 is transmitted to the left and right rear wheels 7L and 7R via a differential (not shown) and drive shafts 12L and 12R, respectively.

  An inverter 13 is connected to the motor 11. A drive battery 14 that can be charged with power supplied from an external power source is connected to the inverter 13, and DC power is supplied from the drive battery 14. The inverter 13 converts the DC power from the driving battery 14 into AC power and supplies the AC power to the motor 11.

  Brakes 15 are provided on the front wheels 6L and 6R and the rear wheels 7L and 7R, respectively. A brake pedal 16 that is operated by a driver's foot is provided in the passenger compartment 3. The brake pedal 16 is connected to a brake booster 18 provided integrally with the master cylinder 17.

  When the brake pedal 16 is depressed, the pedaling force input to the brake pedal 16 is transmitted to the brake booster 18. The pedaling force transmitted to the brake booster 18 is amplified (boosted) by the negative pressure of the brake booster 18 and input from the brake booster 18 to the master cylinder 17. In the master cylinder 17, a hydraulic pressure corresponding to the force input from the brake booster 18 is generated.

  The hydraulic pressure of the master cylinder 17 is transmitted to the brake actuator 19. The brake actuator 19 incorporates a valve for controlling the hydraulic pressure of the wheel cylinder provided in each brake 15, a pump for returning the brake fluid to the master cylinder 17, and the like. The hydraulic pressure transmitted from the master cylinder 17 to the brake actuator 19 is distributed and transmitted to the wheel cylinder of each brake 15. A braking force is applied from the brake 15 to the front wheels 6L and 6R and the rear wheels 7L and 7R by the hydraulic pressure of the wheel cylinder.

  The vehicle 1 is provided with a hydraulic control valve 20. By opening and closing the hydraulic control valve 20, the hydraulic pressure can be transmitted / interrupted to the brake actuator 19 in a system different from the hydraulic pressure generated by the master cylinder 17.

  The vehicle 1 includes a VCU (vehicle control unit) 21, a brake ECU (electronic control unit) 22, and a PCS (Pre-Crash Safety) ECU 23. The VCU 21, the brake ECU 22 and the PCSECU 23 can communicate with each other using a CAN (Controller Area Network) communication protocol.

  The inverter 13 is connected to the VCU 21 as a control target. The VCU 21 sets a torque command value corresponding to the target value of torque output from the motor 11, and controls the inverter 13 so that a current corresponding to the torque command value is supplied from the inverter 13 to the motor 11. The VCU 21 controls the inverter 13 to operate the motor 11 as a generator.

  A brake actuator 19 and a hydraulic control valve 20 are connected to the brake ECU 22 as control targets. The brake ECU 22 controls the brake actuator 19 based on a command given from the VCU 21 when the brake pedal 16 is depressed. Under the control of the brake actuator 19, the hydraulic pressure transmitted from the master cylinder 17 to the brake actuator 19 is distributed to the wheel cylinders of each brake 15, so that the braking force is applied from the brake 15 to the front wheels 6L, 6R and the rear wheels 7L, 7R. Is granted. Also, the brake ECU 22 controls the brake actuator 19 and the hydraulic control valve 20 based on the automatic brake operation request given from the PCSECU 23. By this control, regardless of the operation of the brake pedal 16, the hydraulic control valve 20 is opened and the hydraulic pressure is transmitted to the brake actuator 19 via the hydraulic control valve 20, and the hydraulic pressure is transmitted from the brake actuator 19 to the wheel of each brake 15. By distributing to the cylinders, braking force is automatically applied from the brake 15 to the front wheels 6L and 6R and the rear wheels 7L and 7R (automatic braking).

  Ultrasonic sensors SO1, SO2, SO3 and SO4 are connected to the PCSECU 23. The PCSECU 23 controls on / off of the ultrasonic sensors SO1, SO2, SO3, SO4. By this control, the ultrasonic sensors SO1, SO2, SO3, SO4 are turned on in a certain time (for example, 90 msec) in this order. Each ultrasonic sensor SO1, SO2, SO3, SO4 is switched from off to on when a certain off time (for example, 270 msec) elapses after being switched from on to off. Specifically, when the ultrasonic sensor SO1 at the right front portion of the vehicle body 2 is turned on for a certain time, the ultrasonic sensor SO1 is switched from on to off and the ultrasonic sensor SO2 at the left front portion of the vehicle body 2 is turned off. When the predetermined time elapses, the ultrasonic sensor SO2 is switched from ON to OFF, and the ultrasonic sensor SO3 at the left rear portion of the vehicle body 2 is switched from OFF to ON. The ultrasonic sensor SO3 is switched from on to off, and the ultrasonic sensor SO4 at the right rear portion of the vehicle body 2 is switched from off to on. When a certain time further elapses, the ultrasonic sensor SO4 is switched from on to off. The operation that the ultrasonic sensor SO1 is switched from OFF to ON is repeated.

  FIG. 3 is a flowchart showing the flow of automatic brake control.

  While each of the ultrasonic sensors SO1, SO2, SO3, SO4 is on, the PCSECU 23 repeatedly executes the automatic brake control shown in FIG.

  Hereinafter, the automatic brake control will be described by taking as an example a case where the ultrasonic sensor SO1 is turned on.

  In the automatic brake control, the PCSECU 23 detects whether an obstacle is detected in the detection area of the ultrasonic sensor SO1 based on whether the ultrasonic sensor SO1 has received an ultrasonic wave (reflected wave) reflected by the obstacle. Is determined (step S1).

  When the ultrasonic sensor SO1 does not receive the reflected wave, the PCSECU 23 determines that no obstacle is detected in the detection area of the ultrasonic sensor SO1 (NO in step S1), and ends the automatic brake control.

  When the ultrasonic sensor SO1 receives the reflected wave, the PCSECU 23 determines that an obstacle has been detected in the detection area of the ultrasonic sensor SO1 (YES in step S1). In this case, the PCSECU 23 determines the distance from the vehicle 1 to the obstacle and the vehicle 1 based on the time required for the ultrasonic sensor SO1 to receive the reflected wave after the ultrasonic wave is transmitted from the ultrasonic sensor SO1 and the vehicle speed. Find the relative speed of the obstacle. Then, by dividing the distance from the vehicle 1 to the obstacle by the relative speed between the vehicle 1 and the obstacle, a predicted collision time (TTC: Time To Collision) is calculated (step S2).

  The vehicle speed is input from the brake ECU 22, for example. As shown in FIG. 2, the brake ECU 22 is connected to a wheel speed sensor 31 for detecting the rotational speeds (wheel speeds) of the front wheels 6L and 6R and the rear wheels 7L and 7R. The brake ECU 22 calculates the wheel speeds of the front wheels 6L and 6R and the rear wheels 7L and 7R based on the detection signal input from the wheel speed sensor 31, and acquires the average value of the wheel speeds as the vehicle speed (body speed). To do.

  Further, the PCSECU 23 calculates a required stop time required for the vehicle 1 to stop, assuming that the vehicle 1 decelerates from the current vehicle speed at a target deceleration (for example, 0.6 G) (step S3).

  Then, the PCSECU 23 determines whether or not the predicted collision time matches the required stop time (step S4). The timing at which the predicted collision time coincides with the required stop time is a timing (collision unavoidable timing) at which the collision between the vehicle 1 and the obstacle cannot be avoided even if the automatic brake is operated after that.

  In addition, since ON / OFF of the ultrasonic sensor SO1 is repeated at a constant period, not only when the predicted collision time completely coincides with the required stop time, but also the predicted predicted time is set as the OFF required time of the ultrasonic sensor SO1 ( For example, even when the time is within a range of 270 msec), it may be included when the predicted collision time coincides with the required stop time.

  If the predicted collision time does not match the required stop time (NO in step S4), that is, if the predicted collision time is longer than the required stop time, the PCSECU 23 determines whether the predicted collision time matches the predetermined warning time. Is determined (step S5). The warning time is set to a value larger than the required stop time. The timing at which the predicted collision time coincides with the warning time is a timing at which there is a high possibility of a collision between the vehicle 1 and an obstacle and a brake operation by the driver is required immediately.

  If the predicted collision time does not coincide with the warning time (NO in step S5), the PCSECU 23 ends the automatic brake control.

  When the predicted collision time coincides with the warning time (YES in step S5), the PCSECU 23 outputs a weak regenerative brake operation request to the VCU 21 (step S6). Upon receiving this operation request, the VCU 21 controls the inverter 13 to operate the motor 11 as a generator. Thereby, in the motor 11, the motive power of the rear wheels 7L and 7R is regenerated into electric power. At this time, the electric power regenerated by the motor 11 is small, and a relatively weak braking force due to the regeneration acts on the vehicle 1 (weak regenerative braking operation).

  After outputting the operation request for the weak regenerative brake, the PCSECU 23 ends the automatic brake control. Thereafter, the PCSECU 23 executes the automatic brake control again, and determines whether or not an obstacle is detected in the detection area of the ultrasonic sensor SO1 (step S1).

  If there is still an obstacle in the detection area of the ultrasonic sensor SO1 (YES in step S1), the PCSECU 23 calculates the predicted collision time and the required stop time again (steps S2 and S3).

  Then, the PCSECU 23 determines whether or not the predicted collision time matches the required stop time (step S4).

  When the vehicle 1 approaches the obstacle and the predicted collision time coincides with the required stop time (YES in step S4), the PCSECU 23 outputs an automatic brake operation request to the brake ECU 22 (step S7). ). In response to this operation request, the brake ECU 22 controls the brake actuator 19 and the hydraulic control valve 20 to operate the automatic brake. By the operation of the automatic brake, a braking force is applied from the brake 15 to the front wheels 6L and 6R and the rear wheels 7L and 7R.

  When the predicted collision time coincides with the required stop time, the PCSECU 23 outputs a regenerative brake operation request to the VCU 21 (step S8). Upon receiving this operation request, the VCU 21 controls the inverter 13 to increase the amount of regeneration by the motor 11. As a result, the braking force of the regenerative brake increases.

  Thereafter, the PCSECU 23 ends the automatic brake control.

  FIG. 4 is a diagram showing temporal changes in the braking force of the regenerative brake, the braking force of the automatic brake, and the resultant force of these braking forces.

  By the automatic brake control described above, a weak regenerative brake operation request is output from the PCSECU 23 to the VCU 21 at the timing T1 when the predicted collision time coincides with the warning time. In response to the operation request, a relatively weak braking force by the weak regenerative brake acts on the vehicle 1. Thereby, it is possible to give the driver a weak feeling of deceleration of the vehicle 1. As a result, the driver can be made aware of the presence of an obstacle present in the traveling direction of the vehicle 1, and a driving operation (for example, a brake operation or a steering operation) for avoiding a collision between the obstacle and the vehicle 1. Can prompt the driver.

  Thereafter, when the vehicle 1 approaches an obstacle, an automatic brake operation request is output from the PCSECU 23 to the brake ECU 22 at a timing T2 at which the predicted collision time coincides with the required stop time. An operation request is output.

  Since the braking force of the automatic brake (braking force by the brake 15) is generated by hydraulic pressure, there is a time lag from the output of the automatic brake operation request until the braking force of the automatic brake rises to the target braking force. On the other hand, since the braking force of the regenerative brake is generated by electrical control, the rise is quick. Therefore, the shortage of the braking force of the automatic brake can be compensated by the braking force of the regenerative brake until the braking force of the automatic brake rises to the target braking force after the output of the operation request for the automatic brake. As a result, since a sufficient braking force can be applied to the vehicle 1 immediately after the output of the automatic brake operation request, the vehicle 1 can be automatically automatically stopped as expected.

  The detection areas of the ultrasonic sensors SO1, SO2, SO3, SO4 are relatively short distance areas. Therefore, when an obstacle is detected, the vehicle 1 and the obstacle are close to each other. However, the vehicle 1 can automatically stop the vehicle 1 better than the millimeter wave radar, the laser radar, and the camera. By using inexpensive ultrasonic sensors SO1, SO2, SO3, and SO4, it is possible to avoid a collision between the vehicle 1 and an obstacle or to reduce damage caused by the collision while reducing costs.

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, as a service brake, a hydraulic brake mechanism that generates a braking force by hydraulic pressure (actuates the brake 15) has been taken up, but not limited to a hydraulic brake mechanism, an air pressure brake mechanism may be employed.

  Further, when the possibility of a collision between the vehicle 1 and an obstacle occurs before the predicted collision time coincides with the warning time, the possibility of the collision is indicated to the driver by the operation of the alarm buzzer or the display on the display. You may be notified. Thereby, it is possible to prompt the driver to perform a driving operation for avoiding a collision between the obstacle and the vehicle 1.

  A city commuter was taken up as vehicle 1. However, the vehicle on which the driving support device is mounted may be a small vehicle such as a light vehicle or a vehicle other than the small vehicle. Further, the driving assistance device can be mounted on various vehicles such as an engine vehicle, a hybrid car, a range extended electric vehicle, and a fuel cell vehicle, without being limited to the electric vehicle.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

1 Vehicle 11 Motor (Motor for traveling)
15 Brake (Service brake)
17 Master cylinder (service brake)
18 Brake booster (service brake)
19 Brake actuator (service brake)
20 Hydraulic control valve (service brake)
21 VCU (regenerative braking means)
22 Brake ECU (automatic brake means)
23 PCSECU (obstacle detection means, request output means)
SO1 ultrasonic sensor SO2 ultrasonic sensor SO3 ultrasonic sensor SO4 ultrasonic sensor

Claims (1)

A driving support device mounted on a vehicle,
Obstacle detection means for operating the ultrasonic sensor to detect an obstacle present in the detection area of the ultrasonic sensor;
Request output means for outputting a request to operate a service brake of the vehicle when there is a possibility that the vehicle collides with an obstacle detected by the obstacle detection means;
Automatic brake means for operating the service brake in response to an output of the request by the request output means;
Regenerative braking means for operating a regenerative brake by operating a motor for traveling of the vehicle as a generator from a request output by the request output means until a braking force of the service brake rises to a target braking force. Including a driving assistance device.

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