JP2013121751A - Driving support apparatus - Google Patents

Abstract

A driving support device capable of operating an electric power steering device when an engine stall occurs due to automatic braking.
An obstacle detection means for detecting an obstacle in a traveling direction, an arrival time evaluation means for evaluating an arrival time to the obstacle, and a vehicle braking means for braking a vehicle according to the arrival time. And a steering assist device 200 for assisting steering by detecting steering of the steering wheel of the driver while the engine is operating, wherein the vehicle braking device brakes the vehicle. When the engine speed decreases and an engine stall occurs, the steering assisting means continues to assist the steering.
[Selection] Figure 2

Description

  The present invention relates to a driving support device that detects steering of a steering wheel of a driver and assists a steering force.

  A technology that detects obstacles ahead and performs automatic braking has been put into practical use. For example, in ACC (Adaptive Cruise Control), automatic braking is performed in accordance with TTC (Time To Collision) with a front obstacle, and in PCS (Precrash Safety), it is determined that a collision is unavoidable based on TTC. Sudden braking can be applied.

  By the way, an electric power steering device (EPS) is often mounted on one of the in-vehicle devices. The EPS detects the driver's steering operation and rotates the steering shaft with an electric motor to assist the driver's steering operation. Accordingly, the driver can steer the steering with a relatively weak steering force.

  A technique for avoiding obstacles using this EPS is also known (see, for example, Patent Document 1). In Patent Document 1, when the target three-dimensional object is not in a moving state, it is avoided by automatic steering. A support device is disclosed.

JP 2008-126957 A

  However, when the EPS is deactivated, the driver feels uncomfortable that the necessary steering torque suddenly increases. Such a sense of incongruity may occur not only when the control unit consciously deactivates EPS as in Patent Document 1, but also when PCS or ACC is activated.

  FIG. 1 is an example of a diagram illustrating the inconvenience of EPS during PCS operation. The control unit of the PCS detects TTC or the like for an object (a front parked vehicle) with a millimeter wave radar or the like. When the TTC falls below the first threshold value (time t1), the control unit gives a feeling of deceleration and alerts the driver. As a result, the vehicle speed gradually decreases. In addition, the engine speed gradually decreases.

  When the driver does not perform the avoidance operation and TTC becomes equal to or smaller than the second threshold (time t2), the control unit determines that the collision is unavoidable and rapidly increases the target deceleration. As a result, the vehicle speed and the engine speed rapidly decrease.

  Here, even if the torque converter is locked up, the AT vehicle and the CVT vehicle release the lockup when the vehicle speed and the accelerator opening satisfy a predetermined condition. On the other hand, the MT vehicle remains connected to the transmission and the engine unless the driver operates the clutch. Therefore, when the vehicle speed and the engine speed decrease and the wheel cannot rotate the engine, the engine stall (hereinafter referred to as the engine stall) is established. ).

  When the engine stops, the alternator also stops, so the vehicle does not generate electricity. Even if the alternator stops, power can be supplied from the battery, but generally, the power supply from the battery to the EPS is stopped when the engine is stopped. This is because when the power is supplied from the battery when the alternator is not generating power, the battery is likely to deteriorate.When the engine is stopped, the auxiliary equipment required for running is not required in the first place. The reason is that there is not enough power.

  However, as described above, if power is not supplied to the EPS due to the operation of the PCS → engine stop, there is a possibility that the driving operation of the driver may be affected.

  In view of the above problems, an object of the present invention is to provide a driving support device capable of operating an electric power steering device when an engine stall occurs due to automatic braking.

  The present invention includes an obstacle detection means for detecting an obstacle in a traveling direction, an arrival time evaluation means for evaluating an arrival time to the obstacle, a vehicle braking means for braking a vehicle according to the arrival time, an engine Driving assistance device for detecting steering of the steering wheel of the driver and assisting steering while the vehicle braking means brakes the vehicle so that the engine speed is reduced. When the engine stall occurs due to a decrease, the steering assisting means continues to assist the steering.

  When an engine stall occurs due to automatic braking, it is possible to provide a driving support device capable of operating the electric power steering device.

It is an example of the figure explaining the inconvenience of EPS at the time of PCS action | operation. It is an example of the block diagram of a driving assistance device. It is an example of the figure explaining the electric power supplied to an electric power steering device. It is an example of the flowchart figure which shows the operation | movement procedure of a driving assistance device. It is an example of the figure explaining the effect of a driving assistance device. It is an example of the flowchart figure which shows the other example of an operation | movement procedure. It is an example of the flowchart figure which shows the other example of an operation | movement procedure.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

When the engine support is detected, the driving support device 100 according to the present embodiment continues the power supply without stopping the power supply from the battery to the electric power steering device 200. By doing this,
(i) In M / T (manual transmission) vehicles,
(ii) The engine braking speed decreased due to the operation of automatic braking systems such as PCS (Precrash Safety) and ACC (Adaptive Cruise Control).
(iii) Even if the driver stops because the clutch is not operated,
(iv) The electric power steering device can continue assisting the steering torque.

  In addition, it is not so many that automatic braking systems, such as PCS and ACC, are mounted in an M / T vehicle now. However, it is expected that the need for preventive safety functions will continue to increase, and if the cost reduction by mass production proceeds, it will be prevalent in M / T cars and small cars.

[Configuration example]
FIG. 2 shows an example of a block diagram of the driving support device 100. The driving support device 100 is mainly realized by a driving support computer 12, a power steering computer 14, a power management control computer 15, and a skid control computer 16 communicating via an in-vehicle network such as CAN. The driving support computer 12, the power steering computer 14, the power management control computer 15, and the skid control computer 16 may be referred to as an ECU (Electronic Control Unit). Since all are forms of a computer, they have general microcomputer configurations such as a CPU, RAM, ROM, input / output I / F, A / D converter, and the like.

  A millimeter wave radar sensor 11 is connected to the driving support computer 12 via a CAN network. The millimeter wave radar sensor 11 is disposed in the center of the front of the vehicle, such as the front grille of the vehicle, and emits millimeter waves at a predetermined angle (for example, 10 degrees left and right with the front as the center). The millimeter wave reflected by the object existing in is received. The millimeter wave radar sensor 11 has a plurality of receiving antennas, and each receiving antenna receives millimeter waves by switching the receiving antennas that can be received in a time-sharing manner with a switch. Specifically, the beat signal is generated by mixing the millimeter wave to be transmitted and the received millimeter wave. The beat signal includes a phase difference between the transmission wave and the reception wave that is proportional to the distance of the obstacle, and a frequency difference that is proportional to the relative speed with the obstacle. The millimeter wave radar sensor 11 detects the distance from the obstacle and the relative speed by performing FFT conversion on the beat signal. Further, the lateral position of the obstacle is detected by utilizing the fact that a phase difference appears in the millimeter wave received by each receiving antenna according to the horizontal position (lateral position) of the obstacle viewed from the host vehicle. In a simple manner, the lateral position of the obstacle can be acquired based on the receiving antenna that has received the strongest millimeter wave. An obstacle may be detected by a camera sensor instead of the millimeter wave radar sensor 11 or in addition to the millimeter wave radar sensor 11.

  The driving support computer 12 determines whether the collision is inevitable based on the distance to the obstacle, the relative speed, and the lateral position of the obstacle. For example, when the lateral position is within a predetermined value (the amount of overlap with the host vehicle is large) and the TTC (Time To Collision) obtained from the relative speed and distance is within a threshold value, it is determined that the collision is inevitable. If it is determined that the collision is unavoidable, the driving support computer 12 transmits a PCS operation request to other computers including the brake control computer 16.

  The yaw rate sensor 13 detects a rotational speed when a center line perpendicular to the axle and passing through the center of the vehicle rotates horizontally with respect to the road surface, and longitudinal and lateral accelerations. That is, it is possible to detect the change speed in the traveling direction and the spin.

  The power management control computer 15 detects ON / OFF of the IG-SW and controls ON / OFF of the IG relay and the ACC relay. For example, when the driver turns on the IG-SW, the engine control computer (not shown) is requested to start the engine. The engine control computer turns on the starter relay and starts the engine. The power management control computer 15 turns on the IG relay when it receives the engine start notification. As a result, electric power is supplied from the battery to the electric power steering apparatus 200 and auxiliary devices (injectors, igniters, actuators such as a fuel pump, sensors) necessary for traveling. When the ACC relay is turned on, power is supplied from the battery to the navigation, AV device, air conditioner (air blower), and the like.

  When the engine control computer detects an engine stall, the power management control computer 15 turns off the IG relay. The OFF of the IG relay is also notified to other computers. Conventionally, the power steering computer 14 detects that the IG relay is turned off, and the electric power steering apparatus 200 is also stopped. The power steering computer 14 of the present embodiment does not stop the electric power steering device 200 even if the IG relay is turned off if a power steering control continuation flag 36 described later is turned on.

  The skid control computer 16 is connected to a brake actuator 18, and the brake actuator 18 is connected to a brake (for example, a wheel cylinder of each wheel) 19. When the brake actuator 18 receives the PCS operation request, the brake actuator 18 controls the opening of the on-off valve of the brake actuator 18 to supply the brake hydraulic pressure to the wheel cylinder. As a result, the vehicle can be automatically braked without the driver depressing the brake pedal. During automatic braking, the skid control computer 16 monitors the rotational speed of each wheel and performs ABS (Anti-locked Braking System) control to reduce the wheel cylinder pressure of the wheel when there is a locked wheel.

  The electric power steering apparatus 200 includes a power steering computer 14 and a steering column ASSY 17. Further, the steering column ASSY 17 has a torque sensor 21, a rotation angle sensor 22, and a motor 23. The torque sensor 21 detects the steering torque of the steering wheel by the driver and outputs it to the power steering computer 14. The rotation angle sensor 22 is a sensor called a resolver, for example, and detects the rotation angle of the motor 23 and outputs it to the power steering computer 14. The motor 23 is, for example, a three-phase AC DC brushless motor, and rotates the steering shaft via a speed reduction mechanism. The power steering computer 14 determines the assist direction based on the torque detected by the torque sensor 21, and calculates the assist torque generated by the motor 23 based on the torque and the vehicle speed detected by a vehicle speed sensor (not shown). In order to obtain this assist torque, the motor current is feedback controlled based on the motor rotation angle and the motor current to generate a PWM signal to control the inverter. As a result, a three-phase current that generates assist torque is supplied from the inverter to the motor 23. And the electric power supplied to this motor 23 is supplied from a battery.

  FIG. 3 is an example of a diagram for explaining the electric power supplied to the electric power steering apparatus 200. It should be noted that the configuration of FIG. 3 has no changes from the conventional configuration. However, the control of the power steering relay 32 by the power steering computer 14 is different. As described above, the power management control computer 15 detects ON / OFF of the IG-SW 37. When the engine is started by turning on the IG-SW 37, the IG relay 35 is controlled to be turned on. Thereby, the battery power is supplied to the power management control computer 15 and the power steering computer 14 via the IG relay 35.

  When the power steering computer 14 is activated by the supply of electric power, it controls the power steering relay 32 to be ON. Accordingly, when the power steering relay 32 is turned on, power is supplied to the power steering computer 14 from two systems. Electric power via the power steering relay 32 is supplied to the motor 23 via the inverter 32.

  The power steering computer 14 detects the voltage of power supplied via the IG relay 35 by the sensor 31. Since the power management control computer 15 controls the IG relay 35 to be turned off by IG-OFF or engine stall, the power steering computer 14 conventionally determines whether or not the motor 23 needs to be controlled based on the voltage value detected by the sensor 31. It was. In other words, when the voltage value detected by the sensor 31 is equal to or less than the threshold value, the power steering computer 14 determines that steering assist is no longer necessary and stops the operation. For this reason, when the IG relay 35 is turned off, the power steering relay 32 is controlled to be turned off.

On the other hand, the power steering computer 14 of this embodiment controls the power steering relay 32 as follows, for example.
I. When the engine speed is equal to or lower than the threshold during PCS operation, the power steering control continuation flag 36 is turned ON.
II. When the voltage value detected by the sensor 31 is equal to or lower than the threshold value, if the power steering control continuation flag 36 is ON, the power steering relay 32 is kept ON. If the power steering control continuation flag 36 is OFF, the power steering relay 32 is turned OFF.
III. When the PCS is released after the PCS is activated, the power steering control continuation flag 36 is turned OFF.

  By such control, even when the IG relay 35 is turned off, the power steering computer 14 can control the motor 23, so that the driver can steer the steering without any sense of incongruity.

[Operation procedure 1]
FIG. 4 is an example of a flowchart illustrating an operation procedure of the driving support device 100. The procedure in FIG. 4 starts when the IG-SW 37 is turned on and the driving support device 100 is activated. The PCS is also activated.

  The engine control computer periodically detects the engine speed from a Ne sensor or the like, and transmits it to another computer via the CAN (S10).

  The driving support computer 12 determines whether or not one or more of the operation conditions of PB, PBA, and FPB are satisfied (S20). PB, PBA, and FPB are specific control names of the PCS and are a kind of PCS. PB is an abbreviation for pre-crash braking (intervention braking), which is a control that alerts the driver with an alarm sound and a warning display, and performs automatic braking if no avoidance operation is detected. PBA is an abbreviation for pre-crash brake assist. When the driver performs a brake operation after alerting the driver with an alarm sound and warning display, pressure assistance is provided even if the brake pedal is not fully depressed. Braking control. FPB means preliminary braking, and is braking control that performs light braking on an object as a preliminary preparation in order to speed up the start of deceleration of PB. In either case, the operating conditions are slightly different, but the present embodiment is characterized by the control at the time of the stall, so any operating conditions may be satisfied.

  When one or more of the operating conditions of PB, PBA, and FPB are satisfied (Yes in S20), the power steering computer 14 determines whether or not the engine speed is equal to or less than a threshold value (S30). This threshold value is higher than the engine speed at which engine stall may occur. That is, before the engine stall occurs, the possibility of engine stall is detected.

  If the engine speed is less than or equal to the threshold value (Yes in S30), the PCS is operating and there is a risk of engine stall. Therefore, the power steering computer 14 sets the power steering control continuation flag 36 so that engine stall may occur. Turn on (S40). As a result, the power steering computer 14 continues the steering support even if an engine stall occurs and the IG relay is turned off.

  Next, the power steering computer 14 determines whether or not all the operating conditions of PB, PBA, and FPB have been satisfied (S50). For example, there is no obstacle in the traveling direction and the accelerator opening exceeds the threshold value (in consideration of the driver's intention to operate), or there is no obstacle in the traveling direction and a predetermined time from the stop. It detects that it has passed. There is a possibility that the vehicle is stalled, but when it is stalled, it may be determined after the engine is restarted.

  When the PCS control is completed (Yes in S50), it is not necessary to forcibly continue the power steering control, so the power steering computer 14 turns off the power steering control continuation flag 36 (S60). Thereafter, the electric power steering device 200 is stopped by turning off the IG relay as in the conventional case.

  Thus, even if an engine stall occurs in S40 and S50, the electric power steering apparatus 200 is not stopped, so that the driver can steer the steering wheel without a sense of incongruity.

FIG. 5 is an example of a diagram illustrating the effect of the driving support device 100 of the present embodiment.
(1) At time t1, the host vehicle is traveling while detecting an obstacle in the traveling direction. The power control of the electric power steering device 200 at this time is in a normal state.
(2) At time t2, the driving support computer 12 determines that the PCS operating conditions are satisfied, and the skid control computer 16 starts braking. After time t2, the power steering computer 14 starts determining whether or not the engine speed has become equal to or less than a threshold value.
(3) When the engine speed becomes equal to or lower than the threshold value at time t3, the power steering computer 14 turns on the power steering control continuation flag 36. Conventionally, if the engine speed decreases as it is, engine stall occurs, power is not supplied to the motor 23, and steering becomes heavy. In this case, even if the driver tries to avoid the obstacle by steering, the steering force is required more than before the engine stall occurs. In this embodiment, an obstacle can be avoided in a state where the driver is assisting steering.
(4) When the PCS control ends at time t4, the power steering computer 14 turns off the power steering control continuation flag 36. Thereafter, the power steering computer 14 can turn off the power steering relay 32 by turning off the IG relay and turn off the power supply from the battery, so that power is not wasted.

[Operation procedure 2]
FIG. 6 is an example of a flowchart showing another example of the operation procedure. The electric power steering device 200 is designed so that the steering assist is stopped (fail-safe control) in order to protect the battery even if the voltage detected by the sensor 31 is lowered and no engine stall occurs. There is something. The voltage detected by the sensor 31 is a battery voltage, but the battery voltage is affected by the amount of power generated by the alternator. Therefore, if the amount of power generated by the alternator decreases due to a decrease in engine speed and the power supply voltage decreases, the steering assist may be stopped before engine stall occurs. Of course, if an engine stall occurs, the power supply voltage is greatly reduced.

  In order to avoid this, in FIG. 6, when the engine speed has decreased below the threshold value in step S30 (Yes in S30), the power steering computer 14 cancels fail-safe control (S32). By doing so, even if the power supply voltage detected by the sensor 31 is lowered, it is possible to avoid the fail safe (stop of steering assist) control.

  Thereafter, the processing up to S60 is the same as that in FIG. 4, but in step S70, the power steering computer 14 returns the fail-safe control (S70). Since the PCS control is completed, the original state can be restored by returning the fail-safe control.

[Operation procedure 3]
FIG. 7 is an example of a flowchart showing another example of the operation procedure. Although the process of FIG. 6 coped with a decrease in the power supply voltage, it is preferable not to decrease the power supply voltage if possible. This is because if the power supply voltage decreases, there is a possibility that sufficient power cannot be supplied to the motor 23.

  Therefore, in the procedure of FIG. 7, the power of comfort equipment such as air conditioning and audio is turned off. By doing so, a decrease in power supply voltage is suppressed. Moreover, the load which an alternator gives to an engine for electric power generation can be reduced, and the decreasing speed of an engine speed falls. Therefore, the occurrence of engine stall can be delayed.

  In step S20, when one or more operating conditions of PB, PBA, and FPB are satisfied (Yes in S20), the driving support computer 12 controls the power supply of the comfort equipment to be turned off (S22). Specifically, for example, the AV device or the air conditioner control computer is requested to turn off the power by CAN communication. As a result, the amount of power generated by the alternator is reduced, the decrease in power supply voltage is suppressed, and the load on the engine is reduced.

  Thereafter, the processing up to S70 is the same as in FIG. 6, but in step S80, the power steering computer 14 controls the power supply of the comfort equipment to be ON (S80). It should be noted that the comfort equipment to be turned on is only required to be turned off in step S22. Since the PCS control is finished, turning on the power of the comfort equipment eliminates the need for the driver to turn on the power and improves operability.

  As described above, in the M / T vehicle equipped with the automatic braking system, the driving support device 100 according to the present embodiment stops the engine because the engine speed decreases due to the automatic braking but the driver does not operate the clutch. However, EPS can continue assisting the steering torque.

11 Millimeter-wave radar sensor 12 Driving support computer 14 Power steering computer 15 Power management control computer 16 Skid control computer 17 Steering column ASSY
100 Driving support device 200 Electric power steering device

Claims (1)

Obstacle detection means for detecting obstacles in the traveling direction;
Arrival time evaluation means for evaluating the arrival time to the obstacle;
Vehicle braking means for braking the vehicle according to the arrival time;
In a driving assistance device having steering steering assisting means for detecting steering of a steering wheel of a driver and assisting steering while the engine is operating,
When the vehicle braking means brakes the vehicle and the engine speed decreases and an engine stall occurs, the steering steering assisting means continues the steering assist,
A driving support device characterized by that.

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