JP2010042717A - Vehicular electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular electric power steering device capable of further stabilizing behavior of the vehicle when a night vision device recognizes a pedestrian. <P>SOLUTION: The vehicular electric power steering device 1 for controlling a steering assist amount by an electric assist motor 16 according to at least steering torque is provided with a correction part (reaction force control part 22 and correction gain calculation part 23) for correcting the steering assist amount according to behavior of the vehicle. The correction part increases a correction amount relative to the steering assist amount than when the night vision device 2 does not recognize the pedestrian when the night vision device 2 for assisting recognition of a driver relative to a living body at the outside of the vehicle recognizes the pedestrian. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric power steering device for a vehicle.

Some vehicle electric power steering devices that reduce the driver's steering force during vehicle steering control the steering assist amount in accordance with the steering torque. In this electric power steering apparatus, generally, the assist torque (steering assist amount) generated by the electric assist motor is increased as the steering torque is increased, and the assist torque is decreased as the steering torque is decreased.
In addition, there is also known an electric power steering device that corrects the assist torque in accordance with the vehicle behavior and stabilizes the vehicle behavior (see, for example, Patent Document 1).

On the other hand, in situations where it is difficult for a driver to recognize a living body such as a pedestrian at night, the living body is detected based on an image obtained by an infrared camera or the like and displayed as a silhouette on a display device. A biological recognition support apparatus that supports recognition of a biological body is known (see, for example, Patent Document 2).
JP 2007-168618 A JP 2006-153777 A

  In a vehicle equipped with the biometric recognition support device, there is a desire to further stabilize the vehicle behavior in preparation for an unexpected situation when the biometric recognition support device recognizes a living body.

  Therefore, the present invention provides an electric power steering device for a vehicle that can further stabilize the vehicle behavior when the biological recognition assisting device recognizes the living body.

The vehicle electric power steering apparatus according to the present invention employs the following means in order to solve the above problems.
The invention according to claim 1 is an electric power steering apparatus for a vehicle (for example, an embodiment to be described later) that controls a steering assist amount by an electric assist motor (for example, an electric assist motor 16 in an embodiment to be described later) according to at least a steering torque. The electric power steering apparatus 1) includes a correction unit (for example, a reaction force control unit 22 and a correction gain calculation unit 23 in an embodiment described later) that corrects the steering assist amount in accordance with vehicle behavior. The vehicle is characterized in that the amount of correction for the steering assist amount is increased when the biometric recognition assisting device that assists the driver in recognizing the living body outside the vehicle recognizes the living body than when the living body is not recognized. This is an electric power steering device.
When the living body recognition support means recognizes the living body, it can be estimated that the driving environment is when the visibility is poor. When the living body recognition support apparatus recognizes a living body, by increasing the correction amount for the steering assist amount more than when the living body is not recognized, when dealing with an unexpected situation at the time of poor visibility such as at night The vehicle behavior can be further stabilized.

  According to the first aspect of the invention, while the living body recognition support means recognizes the living body, the amount of correction with respect to the steering assist amount is increased more than when the living body is not recognized. Since the behavior of the vehicle can be further stabilized when dealing with unforeseen circumstances, stable running is possible even when visibility is poor such as at night.

Hereinafter, an embodiment of an electric power steering apparatus for a vehicle according to the present invention will be described with reference to the drawings of FIGS.
As shown in the configuration diagram of FIG. 1, the vehicle includes an electric power steering device 1 and a night vision device (biological recognition support device) 2.

  First, the night vision device 2 will be described. The night vision device 2 includes a pair of left and right infrared cameras 31 and 32 that are installed at the lower part of the front bumper of the vehicle and are directed to the front of the vehicle, a head-up display device (hereinafter abbreviated as HUD) 33 that displays a detection result image, The alarm device 34 which consists of a speaker etc. and the night vision control part 30 are provided.

The left and right infrared cameras 31 and 32 detect far-infrared rays to capture an infrared image that becomes brighter as the temperature increases, and output the infrared image to the night vision control unit 30.
The HUD 33 is provided so as not to obstruct the driver's front view at the front position of the driver's seat above the instrument panel of the vehicle. The video display section of the HUD 33 is composed of a concave mirror, and reflects and projects an image from the inside of the instrument panel.

  The night vision control unit 30 detects the heat source object from the parallax of both images based on the stereo infrared images obtained from the left and right infrared cameras 31 and 32, and displays the detected white silhouette on the HUD 33. Furthermore, when a pedestrian (living body) is specified from among the heat source objects, the alarm device 34 is activated for alerting, and at the same time, the pedestrian projected on the HUD 33 is highlighted with a conspicuous color frame. This alerting function predicts the time required to reach the position of the pedestrian in a predetermined speed range, and alerts at a timing at which a sufficient avoidance operation can be performed.

  Further, the night vision control unit 30 uses pedestrian recognition flag NIGHT_F = 1 when recognizing a pedestrian and pedestrian recognition flag NIGHT_F = 0 when recognizing a pedestrian as electric power. Output to the EPS control device 20 of the steering device 1.

Next, the electric power steering apparatus 1 will be described. The electric power steering apparatus 1 includes an electric assist motor (hereinafter abbreviated as an assist motor) 16 that generates steering assist torque, a motor rotation speed sensor 12 that detects the rotation speed of the assist motor 16, and steering applied to a steering shaft. Steering torque sensor 11 that detects torque, vehicle speed sensor 13 that detects the current speed (vehicle speed) of the vehicle, yaw rate sensor 14 that detects the yaw rate generated in the vehicle, and illuminance sensor 15 that detects the illuminance around the vehicle The motor drive circuit 17 that drives the assist motor 16 and the EPS control device 20 are provided.
The steering torque sensor 11, the motor rotation number sensor 12, the vehicle speed sensor 13, the yaw rate sensor 14, and the illuminance sensor 15 each output an output signal corresponding to the detected value to the EPS control device 20.

The EPS control device 20 includes an EPS basic control unit 21, a reaction force control unit (correction unit) 22, and a correction gain calculation unit (correction unit) 23.
The EPS basic control unit 21 calculates the EPS basic control amount EPS_VALUE of the assist motor 16 based on the output signals of the steering torque sensor 11, the motor rotation number sensor 12, and the vehicle speed sensor 13. The calculation method of the EPS basic control amount EPS_VALUE is the same as that of a known electric power steering apparatus, and thus detailed description thereof will be omitted. However, generally, as the rotational speed of the assist motor 16 increases (in other words, as the steering angular velocity increases). The EPS basic control amount EPS_VALUE is set to be small, the EPS basic control amount EPS_VALUE is increased as the steering torque is increased, and the EPS basic control amount EPS_VALUE is decreased as the vehicle speed is increased.

  The reaction force control unit 22 calculates a reaction force correction amount CNT_VALUE based on the output signal of the yaw rate sensor 14. The reaction force correction amount CNT_VALUE is a reaction force component that generates torque in a direction to cancel the yaw rate when the yaw rate is generated, for example, when the vehicle is turning, and the reaction force correction amount CNT_VALUE is increased as the yaw rate increases. It is set to be large.

  The correction gain calculating unit 23 corrects the correction gain Night_Gain for the reaction force correction amount CNT_VALUE based on the outputs of the vehicle speed sensor 13 and the illuminance sensor 15 and the night vision information (pedestrian recognition flag NIGHT_F) input from the night vision device 2. Is calculated.

The correction gain calculation process executed in the correction gain calculation unit 23 will be described with reference to FIG.
First, the value of the vehicle speed flag F_V is set based on the vehicle speed detected by the vehicle speed sensor 13. In this embodiment, when the vehicle speed is less than a predetermined value (low / medium speed), the vehicle speed flag F_V = 0 is set, and when the vehicle speed is higher than the predetermined value (high speed), the vehicle speed flag F_V = 1 is set.
Further, the value of the illuminance flag F_Lux is set based on the illuminance detected by the illuminance sensor 15. In this embodiment, the illuminance flag F_Lux = 1 is set when the illuminance is below a predetermined value (nighttime), and the illuminance flag F_Lux = 0 is set when the illuminance exceeds a predetermined value (daytime).

  Then, the values of the vehicle speed flag F_V and the illuminance flag F_Lux and the value of the pedestrian recognition flag NIGHT_F output from the night vision control unit 30 are input to the AND circuit 24. The AND circuit 24 outputs the value of the correction flag F_HOSEI = 1 to the switch 25 when the vehicle speed flag F_V = 1, the illuminance flag F_Lux = 1, and the pedestrian recognition flag NIGHT_F = 1, and the vehicle speed flag F_V and the illuminance When at least one of the flag F_Lux and the pedestrian recognition flag NIGHT_F is 0, the value of the correction flag F_HOSEI = 0 is output to the switch 25.

  The switch 25 operates to output “1.0” as the correction gain Night_Gain with respect to the reaction force correction amount CNT_VALUE when the correction flag F_HOSEI = 0 is input, and when the correction flag F_HOSEI = 1 is input It operates to output “1.5” as the correction gain Night_Gain for the force correction amount CNT_VALUE.

  That is, when the night vision device 2 does not recognize a pedestrian, or when the night vision device 2 recognizes a pedestrian but the vehicle speed is less than a predetermined value (medium / low speed), or the night vision device 2 Recognizes a pedestrian but the illuminance exceeds a predetermined value (in the daytime), the correction flag F_HOSEI = 0 is input to the switch 25. At this time, the correction gain calculation unit 23 sets the correction gain as Night_Gain. “1.0” is calculated.

  Further, when the night vision device 2 recognizes a pedestrian, the vehicle speed is equal to or higher than a predetermined value (high speed), and the illuminance is equal to or lower than a predetermined value (nighttime or the like), the correction flag F_HOSEI = 1 Is input to the switch 25. At this time, the correction gain calculation unit 23 calculates “1.5” as the correction gain Night_Gain.

Then, the EPS control device 20 calculates the EPS correction control amount EPS_HOSEI_VALUE by multiplying the reaction force correction amount CNT_VALUE calculated by the reaction force control unit 22 by the value of the correction gain Night_Gain calculated by the correction gain calculation unit 23, The EPS correction control amount EPS_HOSEI_VALUE is subtracted from the EPS basic control amount EPS_VALUE calculated by the EPS basic control unit 21 to obtain the target current Io of the assist motor 16, and this target current Io is output to the motor drive circuit 17. That is, in this embodiment, the vehicle behavior is estimated based on the yaw rate, and the control amount for the assist motor 16 is corrected in a direction that stabilizes the vehicle behavior.
In the motor drive circuit 17, feedback control is performed so that the actual current of the assist motor 16 matches the target current Io.

  According to the electric power steering device 1 configured as described above, the night vision device 2 recognizes a pedestrian, the vehicle speed is equal to or higher than a predetermined value (high speed), and the illuminance is equal to or lower than a predetermined value. In some cases (such as at night), the correction gain Night_Gain is set to 1.5, and the night vision apparatus 2 is set to a value larger than the correction gain Night_Gain = 1.0 when the pedestrian is not recognized. The EPS correction control amount EPS_HOSEI_VALUE becomes a larger value than when the vision device 2 does not recognize a pedestrian, and steering assist with more stable vehicle behavior can be performed.

  Here, when the night vision device 2 recognizes a pedestrian, it can be inferred that the driving environment is when the visibility is poor. Therefore, according to the electric power steering device 1, when the visibility is poor at night or the like, The vehicle behavior can be further stabilized when dealing with the situation. Therefore, stable running is possible even when visibility is poor at night.

  In particular, in this embodiment, even if the night vision device 2 recognizes a pedestrian, the EPS correction control amount EPS_HOSEI_VALUE is set to a normal value when driving at low and medium speeds, and the EPS correction control amount EPS_HOSEI_VALUE is set to normal only during high speed driving. Since the value is increased from the value, the vehicle behavior can be further stabilized at a high speed.

  Further, in this embodiment, the EPS correction control amount EPS_HOSEI_VALUE is increased from the normal value only when the ambient illuminance is less than or equal to a predetermined value, so that the vehicle behavior is further stabilized when the pedestrian's behavior prediction is difficult. be able to.

[Other Examples]
The present invention is not limited to the embodiment described above.
For example, in the above-described embodiments, the living body is a pedestrian, but the living body is not limited to a human being and may be an animal such as a dog, a deer, or a bear.

  In the above-described embodiment, as conditions for increasing the correction amount for the steering assist amount from the normal value, (1) recognition of the living body by the living body recognition support device, and (2) the vehicle speed is equal to or higher than a predetermined value. (3) When all three conditions are satisfied, that is, the ambient illuminance is less than or equal to a predetermined value, the correction amount for the steering assist amount is less than the normal value when the condition (1) is satisfied. May be increased, or when the conditions (1) and (2) are satisfied, the correction amount for the steering assist amount may be increased from the normal value, or (1) and (3 ), The correction amount for the steering assist amount may be increased from the normal value.

  Further, the value “1.5” of the correction gain Night_Gain when the EPS correction control amount EPS_HOSEI_VALUE is increased from the normal value is merely an example. If the value is larger than “1” of the normal correction gain Night_Gain, the value is appropriately set. Can be set to

  In the above-described embodiment, the vehicle behavior is estimated from the yaw rate detected by the yaw rate sensor, and the correction amount for the steering assist amount is obtained according to the detected yaw rate. However, the estimation of the vehicle behavior is not limited to this. Absent. For example, the vehicle behavior is estimated based on a deviation between the standard yaw rate calculated based on the steering angle and the vehicle speed and the detected yaw rate detected by the yaw rate sensor (hereinafter abbreviated as yaw rate deviation), and the steering assist is performed according to the yaw rate deviation. A correction amount for the amount may be obtained. Alternatively, these may be combined.

It is a block diagram in the Example of the electric power steering device for vehicles which concerns on this invention. It is a block diagram of the correction gain calculation part in an Example.

Explanation of symbols

1 Electric Power Steering Device 16 Electric Assist Motor 22 Reaction Force Control Unit (Correction Unit)
23 Correction gain calculation unit (correction unit)

Claims (1)

In the vehicle electric power steering device for controlling the steering assist amount by the electric assist motor according to at least the steering torque,
A correction unit for correcting the steering assist amount according to the vehicle behavior;
The correction unit increases the correction amount with respect to the steering assist amount when the biometric recognition support apparatus that supports the driver's recognition of the living body outside the vehicle recognizes the living body than when the living body is not recognized. An electric power steering device for vehicles.

Images