JP4918815B2 - Collision avoidance system - Google Patents

Description

  The present invention relates to a collision avoidance system that avoids a collision or reduces an impact when the host vehicle is predicted to abnormally approach an obstacle, and in particular, can avoid a collision or reduce an impact during fail-safe control. The present invention relates to a collision avoidance system.

  Based on the relative speed between the preceding vehicle and the host vehicle and the distance between the vehicles, if the vehicle is expected to be abnormally close to the preceding vehicle, the pretensioner motor that winds up the seat belt is driven to alert the driver and impact A vehicle seat belt device is known (see, for example, Patent Document 1).

Further, in such a vehicle seat belt device, if the sensor for detecting an abnormal approach of an obstacle or the like is out of order, the pretensional motor may not be driven normally. In that case, fail-safe control for prohibiting output to the pretentive motor has been proposed (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2002-2450 JP 2004-149048 A

  However, if output to the actuator is prohibited as in Patent Document 2, driving assistance for collision avoidance or impact reduction becomes difficult when an abnormal approach of an obstacle is detected. In the collision avoidance system, the pretensioner motor and the wheel pressure control motor of the ABS (Antilock Brake System) are controlled so that the output to these actuators is not limited for collision avoidance or impact mitigation. May be preferred.

  In view of the above-described problems, the present invention provides a collision avoidance system capable of assisting the driver in avoiding operation without limiting the output of the actuator even in a fail-safe state in a collision avoidance system that reduces collision avoidance and impact. The purpose is to do.

To solve the above problems, the present invention provides a collision avoidance system for controlling a vehicle device so as to avoid or impact mitigation of the collision, the obstacle detection means to detect an obstacle approaching the vehicle, the vehicle device due to the component temperature and a control unit comprising a fail-safe state for limiting the output to the onboard device, wherein, if the obstacle abnormally close by the obstacle detecting means is detected Even in the fail-safe state, the output restriction to the in-vehicle device is temporarily released, and collision avoidance or impact reduction control is performed .

In one aspect of the present invention, when the component temperature exceeds the second threshold, the control means does not output to the in-vehicle device, and the component temperature is equal to or higher than the first threshold and equal to or lower than the second threshold. When an obstacle that is abnormally approached is detected by the obstacle detection means, the component temperature is equal to or higher than the first threshold value and the second threshold is set in a fail-safe state that restricts the output to the in-vehicle device according to the component temperature. Even if it is below the threshold value, the output restriction to the in-vehicle device is temporarily released, and collision avoidance or impact reduction control is performed .

In one embodiment of the present invention, the control means temporarily sets the output to the in-vehicle device to a maximum value when an obstacle that is abnormally approached is detected by the obstacle detection means .

  In a collision avoidance system that reduces collision and reduces impact, it is possible to provide a collision avoidance system that can assist the driver in avoiding operation without limiting the output of the actuator even in a fail-safe state.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The collision avoidance system according to the present embodiment is determined to have a high possibility of abnormally approaching an obstacle even in a state where the output to the actuator is restricted due to overheating of parts or a drop in battery voltage. First, by canceling the output restriction to the actuator, the collision avoidance with the obstacle and the impact reduction control are performed.

  FIG. 1 shows a schematic functional block diagram of a collision avoidance system 1. The collision avoidance system 1 includes a pre-crash ECU 17 that controls the pre-crash safety system, a brake ECU 18 that controls the pressure in the wheel cylinder of each wheel, a steering control ECU 19 that forcibly steers or assists steering, and the suspension of each wheel. An electronic control suspension ECU for controlling the damping force. Each ECU controls a connected actuator to avoid collision or reduce impact. The collision avoidance system 1 does not require all of them, and means for detecting the approach of an obstacle, and when an abnormal approach of the obstacle is detected, controls the actuator to avoid the collision and reduce the impact. Any control can be used as long as it executes the above control.

  Each ECU is a microcomputer in which a CPU, a ROM, a RAM, an NV-RAM (Non-Volatile RAM), a communication unit, and the like are connected by a bus. The CPU executes a program stored in the ROM, and performs control described later. Execute.

  In addition to being supplied as a drive source for the pre-crash ECU 17, the voltage supplied from the battery 15 is supplied to the brake ECU 18, the steering control ECU 19 and the electronic control suspension ECU 27 after being stabilized by a power circuit or the like. The battery 15 supplies power to various actuators that drive the in-vehicle device.

  The pre-crash ECU 17 is provided with a CAN (Controller Area Network) I / F 9 and a temperature sensor 17a for inputting signals from each sensor such as a battery 15, a vehicle speed signal from the vehicle speed sensor 11, a detection signal from the radar sensor 12 through a power supply circuit. And are connected.

  The pre-crash ECU 17 outputs a control signal for driving the motor M24 that winds up the seat belt 31 provided on the occupant's seat via the bridge 21 that switches the rotation direction of the motor M24. The rotational speed of the motor M24 is controlled by the duty ratio controlled by the pre-crash ECU 17.

  The vehicle speed sensor 11 measures, for example, a change in magnetic flux as a pulse when a convex portion provided at regular intervals passes on the circumference of a rotor provided in each wheel, and based on the number of pulses per unit time. The vehicle speed is measured for each wheel.

  The laser sensor 12 includes a transmitter circuit that transmits a pulsed laser, a receiver circuit that receives a pulse laser reflected back from an obstacle, a timer circuit that measures the time from transmission to reception, and a measurement It consists of a microcomputer that calculates the distance to the obstacle based on the time. The radar sensor 12 continuously transmits laser pulses while changing the laser pulse transmission direction so that the laser scans a predetermined range in the vehicle traveling direction. Therefore, the direction and shape of the obstacle can be recognized from the reflection direction of the laser pulse.

  The pre-crash ECU 17 calculates the distance and relative speed to the obstacle ahead based on the detection signal of the radar sensor 12, judges the possibility of abnormal approach to the obstacle, and judges that the possibility of abnormal approach is high. If so, the current flowing through the motor M24 is controlled at a predetermined duty ratio to wind up the seat belt 31. An obstacle in the vehicle traveling direction may be detected by a camera.

  The brake ECU 18 is connected to the battery 15, a CAN I / F 9 for inputting signals from each sensor, a master cylinder (hereinafter referred to as M / C) 16, a brake pedal stroke sensor 8, a temperature sensor 18 a, and a brake pressure control device 22. Has been. The braking force of each wheel is obtained by supplying the hydraulic pressure generated in the M / C 16 to the wheel cylinder 32 of each wheel via the hydraulic circuit according to the amount of operation of the brake pedal by the driver. In addition, the brake which supplies the braking pressure controlled to the wheel cylinder 32 by opening and closing the valve of a hydraulic circuit with an actuator according to the stroke amount of a brake pedal from a high pressure accumulator generated and accumulated separately from the M / C 16 It may be a device.

  When the vehicle speed of each wheel is input to the brake ECU 18 and it is determined that the wheel is slipping, ABS (Antilock Brake System) control is performed to control the wheel cylinder pressure of the wheel. For example, the ratio of the wheel speeds of the other wheels to the wheel speed having the highest rotational speed among the wheel speeds of each wheel is obtained as a slip ratio, and the slip ratio of any wheel is larger than the reference value for starting ABS control. Then (when the ABS control start condition is satisfied), the brake pressure control device 22 operates the pressure valve of the hydraulic circuit so that the brake slip ratio is within a predetermined range for the wheel until the ABS control end condition is satisfied. To increase or decrease the pressure in the wheel cylinder.

  The brake ECU 21 controls the wheel cylinder pressure of each wheel and the opening of the engine throttle as needed when the drive wheel slips during transmission or acceleration, thereby reducing the drive wheel slip during starting or acceleration. Perform traction control control.

  The brake ECU 18 performs brake assist control. The brake ECU 18 detects the speed at which the brake pedal is depressed by monitoring the stroke amount of the stroke sensor 8. If the brake ECU 18 determines that the brake is an emergency brake, the brake ECU 18 drives an actuator provided in the vacuum booster. To increase the braking force.

  The brake ECU 18 performs stability control control. The brake ECU 18 is connected to a lateral G sensor 13 that detects acceleration in the vehicle width direction of the vehicle and a steering angle sensor 14 that detects the steering angle of the driver. When the brake ECU 18 determines that the direction of the vehicle body is oversteered compared to the steering angle based on the steering angle detected by the steering angle sensor 14 and the lateral G value detected by the lateral G sensor 13, the wheel cylinder of the front wheel outside the corner If the pressure is increased and it is determined that the engine is understeering, the engine output is reduced and the wheel cylinder pressure on the rear wheel inside the corner is increased. The engine output control is requested to communicate with the engine ECU to control the throttle opening.

The steering control ECU 19 receives the battery 15 and a signal from each sensor CAN.
It is connected to the I / F 9, the temperature sensor 19a, and the steering motor 23 that rotates the steering shaft.

  The steering shaft is connected to a pinion of a rack and pinion mechanism provided in the gear box, and a rack shaft that reciprocates by engagement of the rack and pinion is connected to the left and right front wheels via tie rods. The steering motor 23 is disposed coaxially with the rack shaft and assists the driver's steering by applying rotational torque to the rack shaft.

  The gear box or the steering shaft is provided with a steering torque sensor 29 for detecting the steering torque, and the vehicle speed is input to the steering control ECU 19 together with the steering torque. The steering control ECU 19 calculates a target value of torque to be supported based on the driver's steering torque and vehicle speed, and outputs it to the steering motor 23. This reduces the force required for steering during normal driving.

  The electronically controlled suspension will be described. The electronically controlled suspension is a suspension device in which a vehicle body is suspended by a spring and a damper, and a motor 25 that switches and controls a damping force is provided on an upper portion of the damper.

  The rotary valve integrally connected to the motor 25 has a plurality of large and small orifices. When the motor 25 is driven, the rotary valve rotates to open and close the orifice, thereby changing the flow rate of the oil passing through the damper 26. The damping force can be switched in multiple stages.

  The electronic control suspension ECU 27 that controls the electronically controlled suspension is connected to a battery 15, a CAN I / F 9 that inputs a signal from each sensor, a temperature sensor 27 a, and a motor 25 that rotates a rotary valve of the damper 26. Further, a road surface sensor 28 that detects a road surface state and a vertical G sensor 30 that detects acceleration in the vertical direction of the vehicle body are connected. The electronic control suspension ECU 27 controls the motor 25 of each wheel suspension according to the road surface unevenness detected by the road surface sensor 28 and independently controls the damping force of each damper 26.

  In the electronically controlled suspension, an air spring may be used instead of the spring. By dividing the air chamber of the air spring into two main and sub, and letting air in and out through the air sealing port, the spring force can be divided into two stages, and the vehicle height against changes in the number of passengers and vehicle weight Can be kept constant. Air in / out is controlled by switching the air passage by an air valve driven by an actuator.

  The pre-crash ECU 17, the brake ECU 18, the steering control ECU 19, and the electronic control suspension ECU 27 are connected to each other. When the pre-crash ECU 17 detects an abnormal approach with an obstacle, it outputs a collision prediction signal to each ECU.

  The brake ECU 18 performs brake assist control and starts braking when an abnormal approach to an obstacle is predicted, and performs ABS control when the driver starts sudden braking and the wheel slips. . In the case of a brake device that supplies braking pressure from a high-pressure accumulator, braking can be started without the driver's braking operation. In addition, when the driver suddenly steers the brake or steering and the vehicle slips, stability control is performed.

  Further, when an abnormal approach to an obstacle is predicted, the steering control ECU 19 detects the approach direction by the laser sensor 12 and controls the steering motor 23 to steer in the direction opposite to the approach direction.

  In addition, when an abnormal approach to an obstacle is predicted, the electronic control suspension ECU 27 controls the damping force of the suspension so as to reduce the nose dive in which the front suspension sinks more than the rear suspension due to braking. That is, the electronic control suspension ECU 27 controls the motor 25 of the damper 26 of each wheel to set the front contraction side harder than the normal control value and set the rear extension side harder than the normal control value. To do.

[Fail-safe control]
As shown in FIG. 1, various sensors are connected to each ECU, and appropriate control as described above is performed based on these detected values. However, if there is an abnormality in the in-vehicle device that cannot obtain the detection value of the sensor required for control, there is a possibility that appropriate control may not be performed, so each ECU performs fail-safe control if there is an abnormality in the in-vehicle device To do. The logic of fail-safe control differs for each ECU. For example, the motor 24, the brake pressure control device 22, the steering motor 23, or the motor 25 (hereinafter collectively referred to simply as actuators) according to sensor failure conditions. Control to stop or limit output to.

  The fail safe control is also executed when the battery voltage is not sufficient. When the battery voltage is low, the actuator cannot exhibit its original performance, or when the battery voltage is low, operating the actuator may cause resource competition such as the headlamp and the room light becoming dark. For this reason, when the battery voltage is low, output to the actuator is limited as fail-safe control.

FIG. 2 is a diagram illustrating an example of output restriction to the actuator when the battery voltage is low. In FIG. 2, the relationship between the battery voltage and the output of the actuator is defined. If the battery voltage is equal to or higher than B [V], 100% power is provided to the actuator. In addition, since the actuator cannot be driven below A [V], no electric power is provided. Battery voltage is A to B
The output is limited at a ratio defined in association with the battery voltage. As described above, when the battery voltage is low, each ECU restricts the output to the actuator such as a duty ratio based on the output restriction as shown in FIG. In addition, since the electric power required for control differs for each actuator, the output restriction can be controlled for each ECU.

  Moreover, fail safe control is performed also when components overheat. If each ECU, switch element, etc. are overheated, the function will be reduced and thermal destruction will occur, so the output to the actuator will be limited by fail-safe control. The temperature sensors 17a, 18a, 19a, and 27a connected to each ECU output the temperature of each ECU and the temperature of the actuator drive circuit.

  FIG. 3 is a diagram showing an example of component temperature and output limitation to the actuator. If the component temperature is C [° C.] or less, 100% electric power is provided to the actuator. Moreover, since there exists a possibility that a function fall and thermal destruction may arise above D [degreeC], electric power is not provided. When the component temperature is between C and D, the output is limited at a ratio defined in association with the component temperature. As described above, when the component temperature is high, each ECU restricts the output to the actuator such as a duty ratio based on the output restriction as shown in FIG. Since the temperature characteristics are different for each part, the output restriction can be controlled for each ECU and each part.

[Release output limit during fail-safe control]
During fail-safe control, the output to the actuator is stopped or the output is limited in this way, but even if it is during fail-safe control, if the cause is a decrease in battery voltage or overheating of parts, It may be possible to drive the actuator. For example, in the case of fail-safe control due to a decrease in battery voltage, it is not necessary to limit the output to the actuator as long as the headlamp and the room lamp are allowed to be dark. Further, in the case of fail-safe control due to an increase in component temperature, there is often no deterioration in function or thermal destruction even if the output to the actuator is not limited if it is temporary. For this reason, when obstacles approach abnormally, even if fail-safe control is performed due to a decrease in battery voltage or overheating of parts, it is easy to avoid collision and reduce impact by releasing the output restriction to the actuator. Therefore, it is preferable. The cancellation of the output restriction at the time of fail safe control will be described.

  FIG. 4 is a flowchart showing a control procedure in which the collision avoidance system performs fail-safe control. The control procedure in FIG. 4 is control that can be executed for each ECU of the collision avoidance system, and parameters such as a threshold value are different for each ECU.

  First, each ECU determines whether or not it is in a fail-safe control state (S1). If it is not in the fail safe state (No in S1), since the collision avoidance system is in a normal state in this case, the output to the actuator is not limited (S6).

  In the fail-safe state (Yes in S1), it is determined whether or not the cause of the fail-safe control is due to the battery voltage or the component temperature (S2).

  When fail-safe control is not performed due to battery voltage or component temperature (No in S2), a factor other than battery voltage or component temperature, for example, a fail-safe state due to a sensor abnormality, output to the actuator by fail-safe control according to the factor (S5).

  In the case of fail-safe control based on battery voltage or component temperature (Yes in S2), the pre-crash ECU 17 determines whether or not there is a high possibility of abnormally approaching an obstacle (S3). When the possibility of abnormal approach is low (No in S3), the output to the actuator is limited by fail-safe control according to the factor (S5).

  When there is a high possibility of abnormally approaching an obstacle (Yes in S3), each ECU temporarily cancels the output limit or increases the limit value (S4).

  FIG. 5A is a diagram illustrating a relationship between the battery voltage and the output restriction when the output restriction due to the battery voltage is released. In addition, a dotted line is an output restriction | limiting when the battery voltage shown in FIG. As shown in FIG. 5A, each ECU temporarily controls the actuator with an output of 100% even if the battery voltage is A to B [V].

  FIG. 5B is a diagram showing the relationship between the component temperature and the output limitation when the output limitation due to the component temperature is released. In addition, a dotted line is an output restriction | limiting when components temperature is between C-D shown in FIG. As shown in FIG. 5B, each ECU temporarily controls the actuator with an output of 100% even if the component temperature is C to D [° C.].

  FIG. 5A or FIG. 5B is an example of canceling the output restriction. In the case of battery voltage, the region on the left side of the dotted line in FIG. The output restriction may be corrected so that the area on the right side of FIG. That is, the output limit value defined in association with the battery voltage or the component temperature of the in-vehicle device may be increased so as to increase the limit value at the time of fail-safe control with respect to the battery voltage or the component temperature.

  Then, each ECU cancels the output restriction (S4), or according to the output restriction according to a factor other than the battery voltage or the component temperature (S5), or without fail-safe control (S6). In order to avoid and reduce the impact, the seat belt 31 is wound up, braking is started, steering is performed in a direction to avoid a collision, and the damping force of the damper is controlled (S7). When the output restriction is temporarily released due to the battery voltage or the component temperature, the output restriction is restored after the control such as shock reduction.

  As described above, the collision avoidance system 1 according to the present embodiment temporarily cancels the output restriction when it is determined that the obstacle approach is abnormally approached at the time of fail-safe control due to a decrease in battery voltage or overheating of parts. Functions for collision avoidance and impact mitigation can be temporarily restored. In the case of battery voltage drop or component overheating, the load on the power system and components can be tolerated even if the output is not limited temporarily, so collision avoidance, impact reduction, ensuring other vehicle functions and component protection Can be compatible.

  In the present embodiment, the collision avoidance system 1 is exemplified by a pre-crash seat belt, brake assist, electronic control steering, electronic control suspension, etc. It can be applied to any system. For example, in an electronically controlled stabilizer in which a swing type actuator is provided on the stabilizer bar, a part of the stabilizer bar is used by the actuator to reduce the roll of the vehicle when the vehicle is suddenly steered to avoid a collision. To control the vehicle height on one side. The collision avoidance system 1 according to the present embodiment is abnormally close to an obstacle during fail-safe control due to a decrease in battery voltage or overheating of a component, such as an electronic control stabilizer, that consumes electric power for collision avoidance. If it is determined, the output restriction can be temporarily released.

It is a schematic functional block diagram of a collision avoidance system. It is a figure which shows an example of the output restriction | limiting to an actuator when a battery voltage is low. It is a figure which shows an example of component temperature and the output restriction | limiting to an actuator. It is a flowchart figure which shows the control procedure in which a collision avoidance system performs fail safe control. It is a figure which shows the relationship between a battery voltage when the output restriction resulting from a battery voltage is cancelled | released, and an output restriction.

Explanation of symbols

1 Collision Avoidance System 8 Stroke Sensor 9 CAN I / F
11 Vehicle speed sensor 12 Radar sensor 13 Lateral G sensor
14 Steering angle sensor 15 Battery 16 M / C
17 Pre-crash ECU
18 Brake ECU
19 Steering control ECU
27 Electronically controlled suspension ECU

Claims (3)

In a collision avoidance system that controls an in-vehicle device to avoid collision or reduce impact,
And the obstacle detection means to detect an obstacle approaching the vehicle,
And a control means comprising a fail-safe state for limiting the output to the vehicle device due to the component temperature of the in-vehicle device,
When the obstacle detecting means detects an obstacle that is abnormally approaching, the control means temporarily cancels the output restriction to the in-vehicle device even in the fail-safe state, and avoids collision or reduces impact. Do control,
A collision avoidance system characterized by that. The control means does not output to the in-vehicle device when the component temperature exceeds the second threshold, and outputs to the in-vehicle device when the component temperature is equal to or higher than the first threshold and equal to or lower than the second threshold. It becomes a fail-safe state that limits depending on the part temperature,
When an obstacle that approaches abnormally is detected by the obstacle detection means,
Even if the component temperature is equal to or higher than the first threshold value and equal to or lower than the second threshold value, the output restriction to the in-vehicle device is temporarily released, and the collision is avoided or the impact is reduced.
The collision avoidance system according to claim 1. The control means, when an obstacle that approaches abnormally is detected by the obstacle detection means,
The collision avoidance system according to claim 2, wherein an output to the in-vehicle device is temporarily maximized .

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