JP2002200985A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device for a vehicle capable of appropriately switching an operation mode in response to the will of a driver. SOLUTION: When a turning angle of an output shaft 2B is changed prior to a turning angle of an input shaft 2A and the quantity of a change of the turning angle of the input shaft 2A within a constant time is a predetermined value or less, a determination that the driver removes hands from a steering wheel 1 is done, and the operation mode is changed to an automatic operation mode for automatically steering a steering mechanism 3 so that a vehicle travels along a lane on a road. When the turning angle of the input shat 2A is changed prior to the turning angle of the output shaft 2B, a determination that the driver operates the steering wheel 1 is done, and an electric motor 4 is driven on the basis of the operation of the steering wheel 1 by the driver, and torque generated from the electric motor 4 is given to the steering mechanism 3 to switch the operation mode to an assist mode for conducting an auxiliary steering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, a camera for capturing an image in front of a vehicle is mounted on the vehicle, and steering is performed so that the vehicle travels along a lane on a road based on an image signal output from the camera. There has been proposed an automatic steering device for automatically steering a mechanism. Further, it has been proposed to use an actuator provided in a power steering device as an actuator for generating torque for automatic steering. That is, since the power steering device is provided with an actuator such as an electric motor or a hydraulic cylinder incorporated in the steering mechanism, by controlling this actuator based on the image signal output from the vehicle-mounted camera, Such automatic steering of the steering mechanism can be achieved.

[0003] By the way, it is assumed that the driver wants to change lanes on his own in the course of automatic steering. Therefore, the automatic steering device is provided with an automatic steering mode and a manual steering mode in which steering according to the steering operation is performed, and it is desired that these operation modes are appropriately switched according to the driver's intention. I have.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to provide a vehicle steering apparatus whose operation mode can be appropriately switched according to the driver's intention. It is to be.

[0005]

According to the first aspect of the present invention, an input shaft (2A) coupled to an operating member (1) operated by a driver and a steering wheel are provided. A vehicle steering system including a steering shaft (2) configured so as to be rotatably connected to an output shaft (2B) coupled to a mechanism (3), wherein a driving force to be applied to the steering mechanism is provided. A driving force generating means for generating the driving force; and an automatic steering control means for controlling the driving force generating means so that the vehicle runs autonomously.
An assist control means (73) for controlling the driving force generating means based on an operation of the operating member; an input-side rotation angle detection means (61) for detecting a rotation angle of the input shaft; An output-side rotation angle detecting means (62) for detecting the input shaft rotation angle detected by the input-side rotation angle detection means and a rotation angle of the output shaft detected by the output-side rotation angle detection means; Release determination means (75) for determining whether the driver's hand has been released from the operating member
And mode switching means (76) for switching an operation mode between an automatic steering mode by the automatic steering control means and an assist mode by the assist control means based on a result of the judgment by the release judgment means. Vehicle steering system.

[0006] Alphanumeric characters in parentheses indicate corresponding components in the embodiment described later. Hereinafter, the same applies in this section. According to the present invention, the operation mode is switched between the automatic steering mode by the automatic steering control means and the assist mode by the assist control means based on whether or not the driver's hand is released from the operating member. That is, the operation mode can be switched depending on whether or not the driver releases the operating member. Therefore, appropriate switching of the operation mode according to the driver's intention can be achieved.

Whether the driver's hand has been released from the operating member is determined based on the rotation angles of the input shaft and the output shaft. Specifically, for example, in the automatic steering mode, the rotation angle of the output shaft detected by the output-side rotation angle detection means is detected by the input-side rotation angle detection means. If the change amount of the rotation angle of the input shaft detected by the input-side rotation angle detection means within a certain time is equal to or less than a predetermined value, the operation member is changed. It can be determined that the driver has released his hand. Further, for example, in the assist mode, the rotation angle of the input shaft detected by the input-side rotation angle detecting means is determined by the output-side rotation angle detecting means. If the rotation angle changes before the rotation angle, it can be determined that the operation member is operated by the driver's hand.

The mode switching means switches the automatic steering mode to the assist mode from the automatic steering mode when the release judgment means determines that the operating member is being operated by the driver's hand. Switching condition 1
It is preferable to include one of them. According to a fifth aspect of the present invention, one of the conditions for switching from the assist mode to the automatic steering mode includes that the release of the driver's hand has been released from the operating member by the release determination means. preferable.

According to a sixth aspect of the present invention, the running locus of the vehicle at a predetermined time until the release of the driver's hand from the operating member by the release determination means crosses the lane on the road. Lane intersection detection means (8, 9, T3) for detecting whether or not the driver's hand has been released from the operating member by the release determination means; 6. The vehicle steering apparatus according to claim 5, wherein the mode is switched from the assist mode to the automatic steering mode on condition that the detection means detects that the traveling locus of the vehicle does not cross the lane.

If the traveling locus of the vehicle at a predetermined time intersects with the lane, it is considered that the traveling lane (lane) of the vehicle has been changed (lane change) within the predetermined time. In such a case, when the mode is switched from the assist mode to the automatic steering mode, if the automatic steering control means controls the driving force generating means so that the vehicle travels along the lane, before the lane change is performed. May be returned to the traveling lane.

According to the invention of claim 6, it is possible to prevent the driver from returning to the original lane due to the switch from the assist mode to the automatic steering mode despite the driver's intention to change lanes. Can prevent the occurrence of danger due to the switching of the operation mode that is not desired.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a vehicle steering system according to one embodiment of the present invention. The steering torque applied to the steering wheel 1 is transmitted to the steering mechanism 3 via the steering shaft 2. Also, the steering mechanism 3
, A driving force generated from the electric motor 4 is transmitted.

The steering shaft 2 is divided into an input shaft 2A connected to the steering wheel 1 side and an output shaft 2B connected to the steering mechanism 3 side.
The input shaft 2A and the output shaft 2B are connected to each other by a torsion bar 5. Torsion bar 5
The torsion bar 5 is twisted in response to the steering torque, and the torsion bar 5 causes the input shaft 2A and the output shaft 2B to relatively elastically rotate about the same coaxial center.

In connection with the input shaft 2A, an input resolver 61 for detecting the rotation angle of the input shaft 2A is provided. An output resolver 62 for detecting the rotation angle of the output shaft 2B is provided in relation to the output shaft 2B.
The input-side resolver 61 and the output-side resolver 62 output sine-wave signals whose phases change in accordance with changes in the rotation angles of the input shaft 2A and the output shaft 2B, respectively. It is input to a controller (ECU) 7 including a computer.

The controller 7 includes an input resolver 61.
In addition to the output signal of the output-side resolver 62, an image signal from the vehicle-mounted camera 8 that captures an image in front of the vehicle equipped with the steering device, and a vehicle speed sensor 9 that detects the traveling speed (vehicle speed) of the vehicle. An output signal and an output signal of a motor current sensor 10 that detects a motor current flowing through the electric motor 4 are input. The controller 7
The drive of the electric motor 4 is controlled based on input signals from the above-mentioned sensors and the like.

FIG. 2 is a block diagram showing the configuration of the controller 7. The controller 7 has a plurality of function processing units realized by the microcomputer executing the program processing. These function processing units include an automatic control unit 72 that controls a motor driver 71 for driving the electric motor 4 in the automatic steering mode, an assist control unit 73 that controls the motor driver 71 in the assist mode, an input resolver 61, Output resolver 6
2, a steering torque calculating unit 74 for calculating the steering torque from the output signal, a release judgment unit 75 for judging whether or not the driver has released the steering wheel 1, and an automatic operation according to the judgment result of the release judgment unit 75. A mode switching unit 76 for switching between the steering mode and the assist mode is included.

The automatic steering mode is a mode in which the steering mechanism 3 is automatically steered so that the vehicle travels along a lane on the road. The automatic control unit 72 calculates the target steering angle of the steering wheel such that the vehicle travels along the lane based on, for example, an image in front of the vehicle captured by the vehicle-mounted camera 8 and a vehicle speed detected by the vehicle speed sensor 9. Is determined. Then, a motor instruction current is set based on a deviation between the target steering angle and the actual steering angle (actual steering angle) of the steering wheel obtained from the output signal of the output resolver 62, and the set motor instruction current is set. The motor driver 71 is controlled based on the current.

On the other hand, the assist mode is based on the operation of the steering wheel 1 by the driver.
In this mode, the torque generated by the electric motor 4 is given to the steering mechanism 3 to assist the steering. The assist control unit 73 determines a motor command current according to the vehicle speed and the steering torque, and performs feedback control of the electric motor 4 based on the motor command current. More specifically, a plurality of assist tables defining steering torque-motor instruction current characteristics that are different for each vehicle speed range are stored in a memory (not shown), and an assist table corresponding to the vehicle speed is selected from the plurality of assist tables. Is selected, and a motor instruction current corresponding to the steering torque calculated by the steering torque calculation unit 74 is determined according to the selected assist table. Then, the motor instruction current and the motor current sensor 1
The motor driver 71 is controlled based on the deviation from the motor current detected by 0.

The steering torque calculation unit 74 calculates the steering torque based on the output signals of the input resolver 61 and the output resolver 62.
The steering torque input to the steering wheel 1 by the driver is calculated. That is, the input shaft 2A
The output shaft 2B and the output shaft 2B rotate relative to each other around the coaxial center by the torsion bar 5 being elastically twisted in accordance with the steering torque input to the steering wheel 1. Therefore, the rotation angle of the input shaft 2A and the output shaft The difference from the rotation angle of 2B corresponds to the steering torque input to the steering wheel 1. The steering torque calculator 74 calculates the rotation angles of the input shaft 2A and the output shaft 2B from the output signals of the input resolver 61 and the output resolver 62, and calculates the difference between the obtained rotation angle of the input shaft 2A and the output shaft 2B and the torsion. The steering torque is detected based on the elastic constant (spring constant) of the bar 5.

FIG. 3 shows the controller 7 (the release judgment unit 7).
5 is a flowchart for describing a mode determination process executed by the mode switching unit 5 and the mode switching unit 76). This mode determination process is repeatedly executed until the ignition switch of the vehicle is turned on after being turned on. First, the hand release determination unit 75 detects the rotation angles of the input shaft 2A and the output shaft 2B based on the output signals of the input resolver 61 and the output resolver 62 (step S1).

Subsequently, it is determined whether or not the automatic steering flag has been reset to "0" (step S2).
The automatic steering flag is a flag that indicates whether the current operation mode of the vehicle steering system is the automatic steering mode or the assist mode. Mode, and the state reset to “0” indicates the assist mode. The automatic steering flag is reset to “0” immediately after the ignition switch of the vehicle is turned on.

If the automatic steering flag has been reset to "0", then, in the release judgment section 75, the output shaft 2B
Of the input shaft 2A changes before the rotation angle of the input shaft 2A, and the rotation angle of the input shaft 2 within a certain time (for example, 2 seconds).
It is determined whether or not the change amount of the rotation angle of A is equal to or smaller than a predetermined value (for example, ± 1 degree) (step S3). When the steering wheel 1 is actively operated by the driver, the input shaft 2A rotates before the output shaft 2B,
The amount of change in the rotation angle of the input shaft 2A should also be large.
Therefore, the rotation angle of the output shaft 2B changes before the rotation angle of the input shaft 2A, and the rotation angle of the input shaft 2
When the change amount of the rotation angle of A is equal to or smaller than the predetermined value, it can be determined that the driver has released the steering wheel 1. On the other hand, when the rotation angle of the output shaft 2B changes later than the rotation angle of the input shaft 2A, or when the change amount of the rotation angle of the input shaft 2A within a certain time is larger than a predetermined value, It can be determined that the driver is holding the steering wheel 1.

If the release determination section 75 determines that the driver has released the hand from the steering wheel 1 (YES in step S3), the mode switching section 76
As a result, "1" is set to the automatic steering flag (step S4). Then, the operation mode of the vehicle steering system is switched to the automatic steering mode (step S5), and the control of the motor driver 71 by the above-described automatic control unit 72 is performed. Thereafter, when this mode determination processing is returned, after the detection of the rotation angles of the new input shaft 2A and the output shaft 2B (step S1), whether the automatic steering flag has been reset to "0" following this. The determination as to whether or not it is negative is made (step S2). In this case, the hand release determination unit 75 repeatedly checks whether the rotation angle of the input shaft 2A has changed before the rotation angle of the output shaft 2B (step S).
6). That is, while the automatic steering flag is set to “1” (while the control by the automatic control unit 72 is being performed), the release angle determination unit 75 sets the rotation angle of the input shaft 2A to the rotation angle of the output shaft 2B. It is repeatedly checked whether or not it has changed earlier.

If the rotation angle of the input shaft 2A changes later than the rotation angle of the output shaft 2B, it is determined that the steering wheel 1 has not been gripped yet, and the automatic steering mode is continued. On the other hand, if the rotation angle of the input shaft 2A changes before the rotation angle of the output shaft 2B, it is determined that the steering wheel 1 has been operated by the driver, and the automatic steering flag is reset to “0” (step S).
7) The mode is switched from the automatic steering mode to the assist mode by the mode switching unit 76 (step S8). Then, the control of the motor driver 71 by the assist control unit 73 is started.

On the other hand, if it is determined that the automatic steering flag has been reset to "0" (YES in step S2), and if the release determination unit 75 determines that the driver is holding the steering wheel 1, ( (NO in step S3), the operation mode of the vehicle steering system remains in the assist mode (step S9), and the control of the motor driver 71 by the assist control unit 73 described above is continued. As described above, according to this embodiment, the output shaft 2B
When the rotation angle of the input shaft 2A changes before the rotation angle of the input shaft 2A and the amount of change in the rotation angle of the input shaft 2A within a predetermined time is equal to or less than a predetermined value, the driver releases the steering wheel 1. Is determined, the automatic steering mode is set to automatically steer the steering mechanism 3 so that the vehicle travels along the lane on the road. If the rotation angle of the input shaft 2A changes before the rotation angle of the output shaft 2B while the automatic steering is being performed, it is determined that the steering wheel 1 has been operated by the driver. Mode. Thereby, appropriate operation mode switching according to the driver's intention can be achieved.

FIG. 4 is a flowchart for explaining another example of the mode determination processing. The mode determination process shown in FIG. 4 is also executed repeatedly from the time when the ignition switch of the vehicle is turned on until it is turned off, similarly to the mode determination process shown in FIG. First, it is determined whether or not the automatic steering flag has been reset to "0" (step T1). If the automatic steering flag has been reset to "0", it is next determined whether or not the driver has released the steering wheel 1 (step T2). This determination is the same as that in step S3 shown in FIG. That is, whether the rotation angle of the output shaft 2B changes earlier than the rotation angle of the input shaft 2A and the change amount of the rotation angle of the input shaft 2A within a predetermined time is equal to or less than a predetermined value in the release judgment unit 75. It is determined whether or not.

If it is determined that the driver has released his / her hand from the steering wheel 1, the relationship between the traveling locus of the vehicle and the lane is determined (step T3), and based on the determined relationship, In the mode switching section 76, it is determined whether the mode can be switched from the assist mode to the automatic steering mode (step T4). Specifically, a predetermined time (for example, 3 hours) until the driver determines that the driver has released the steering wheel 1 is released.
If the traveling locus of the vehicle (in seconds) does not intersect the lane, it is determined that the mode may be switched from the assist mode to the automatic steering mode, and the driver may operate the steering wheel 1.
If the traveling locus of the vehicle at a predetermined time until it is determined that the hand has been released intersects with the lane, the hand is released from the steering wheel 1, but the mode should be switched from the assist mode to the automatic steering mode. It is determined that there is not. When the traveling locus of the vehicle at a predetermined time intersects with the lane, it is considered that the traveling lane (lane) of the vehicle has been changed (lane change) within the predetermined time. If the mode is switched to the automatic steering mode in this case, the vehicle may be forced to return to the traveling lane before the lane change due to the characteristics of the automatic steering mode in which the vehicle travels along the lane.

If it is determined that the mode can be switched from the assist mode to the automatic steering mode, an automatic steering start notification sound is output to notify the driver that the vehicle is going into the automatic steering mode (step T5). Then, the automatic steering flag is set to "1" by the mode switching unit 76 (step T6), and the operation mode of the vehicle steering system is switched to the automatic steering mode (step T7). The control of the driver 71 is performed.

Thereafter, when the mode determination process is returned, the determination as to whether or not the automatic steering flag has been reset to "0" is denied (NO in step T1). Then, the release determination section 75 determines whether or not the driver has released the hand from the steering wheel 1 (step T8). This determination is the same as that in step S6 shown in FIG. That is, the hand release determination unit 75 repeatedly checks whether the rotation angle of the input shaft 2A has changed before the rotation angle of the output shaft 2B.

If the rotation angle of the input shaft 2A changes later than the rotation angle of the output shaft 2B, it is determined that the hand is still released from the steering wheel 1 (YES in step T8), and the automatic steering is performed as it is. The mode continues. On the other hand, if the rotation angle of the input shaft 2A changes before the rotation angle of the output shaft 2B, it is determined that the steering wheel 1 has been operated by the driver (NO in step T8), and
An automatic steering cancellation notification sound for notifying the driver that the automatic steering mode is canceled and the vehicle enters the assist mode is output (step T9). Then, the automatic steering flag is reset to "0" (step T10), and the mode switching unit 76 switches from the automatic steering mode to the assist mode (step T11).

On the other hand, if it is determined that the automatic steering flag has been reset to "0" and it is determined that the automatic steering mode should not be switched (step T4).
NO), an automatic steering switching failure sound is output to warn the driver that the vehicle has not been switched to the automatic steering mode (step T12), and the operation mode of the vehicle steering system remains in the assist mode (step T12). Step T1
3) The control of the motor driver 71 by the assist control unit 73 described above is continued. Also, when it is determined that the automatic steering flag has been reset to “0” and it is determined that the hand has not been released from the steering wheel 1 (NO in step T2), the above-described assist control unit 73 Control of the motor driver 71 is continued.

As described above, in the mode determination process shown in FIG. 4, the driver releases the hand from the steering wheel 1 and the traveling trajectory of the vehicle for a certain period of time until the driver releases the hand from the steering wheel 1. The switching from the assist mode to the automatic steering mode is performed only when the vehicle does not cross the lane. This can prevent the driver from returning to the original lane due to the switch from the assist mode to the automatic steering mode even though the driver intends to change lanes. Occurrence can be prevented.

The driver is notified that the operation mode has been switched, and if the driver has not released the steering wheel 1 but has been switched to the automatic steering mode, the driver is notified of the fact. , The driver can accurately know the current operation mode. Although the two embodiments of the present invention have been described above, the present invention can be embodied in other forms. For example, in the above embodiment, an apparatus using an electric motor as an actuator is taken as an example.
The present invention can also be applied to a device using a hydraulic cylinder as an actuator.

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

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle steering system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a controller provided in the vehicle steering device.

FIG. 3 is a flowchart illustrating a mode determination process executed by a controller.

FIG. 4 is a flowchart for explaining another example of the mode determination process.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering shaft 2A input shaft 2B output shaft 3 steering mechanism 4 electric motor 5 torsion bar 7 controller 8 in-vehicle camera 9 vehicle speed sensor 10 motor current sensor 61 input-side resolver 62 output-side resolver 72 automatic control unit 73 assist control unit 75 Release part 76 Mode switching part

Claims (6)

[Claims] 1. A vehicle steering system comprising a steering shaft having an input shaft connected to an operating member operated by a driver and an output shaft connected to a steering mechanism side rotatably connected to each other. A driving force generating means for generating a driving force to be applied to a steering mechanism; an automatic steering control means for controlling the driving force generating means so that the vehicle runs autonomously; and the driving force based on an operation of an operating member. Assist control means for controlling the generating means, input-side rotation angle detection means for detecting the rotation angle of the input shaft, output-side rotation angle detection means for detecting the rotation angle of the output shaft, and the input-side rotation angle detection means Whether the driver's hand has been released from the operating member based on the detected rotation angle of the input shaft and the rotation angle of the output shaft detected by the output-side rotation angle detecting means Release judgment means for judging the condition, and mode switching means for switching an operation mode between an automatic steering mode by the automatic steering control means and an assist mode by the assist control means based on the judgment result by the release judgment means. A vehicle steering system characterized by the above-mentioned. 2. The release means according to claim 1, wherein the rotation angle of the output shaft detected by the output side rotation angle detecting means changes before the rotation angle of the input shaft detected by the input side rotation angle detecting means. When the change amount of the rotation angle of the input shaft detected by the input-side rotation angle detection means within a predetermined time is equal to or less than a predetermined value, it is determined that the driver's hand has been released from the operation member. The vehicle steering system according to claim 1, wherein: 3. The release determination means, wherein the rotation angle of the input shaft detected by the input rotation angle detection means changes before the rotation angle of the output shaft detected by the output rotation angle detection means. 3. The vehicle steering apparatus according to claim 1, wherein in this case, it is determined that the operating member is operated by a driver's hand. 4. The mode switching means includes, as one of conditions for switching from the automatic steering mode to the assist mode, that the release judgment means has determined that the operating member is being operated by the driver's hand. The vehicle steering system according to any one of claims 1 to 3, wherein: 5. The method according to claim 1, wherein said mode switching means includes, as one of conditions for switching from the assist mode to the automatic steering mode, that the release of the driver's hand is determined by said release determination means. The vehicle steering system according to any one of claims 1 to 4, wherein: 6. A lane for detecting whether or not a traveling locus of a vehicle at a predetermined time until a time when a driver's hand is released from an operating member by said release determination means intersects a lane on a road. The mode switching means further includes intersection detection means, wherein the mode release means determines that the driver's hand has been released from the operating member by the release judgment means, and the lane intersection detection means determines that the traveling locus of the vehicle intersects the lane. 6. The vehicle steering system according to claim 5, wherein the vehicle is switched from the assist mode to the automatic steering mode on condition that it is detected that the vehicle is not present.