JPH11180326A - Steering device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To release the steering restraint only by the resistance of a driver to the steering restraint, by reducing the restraint of the steering to the extent to increase the resistance corresponding value corresponding to the extent that the resistance of the driver to the steering restraint is increased, and making the same zero when the resistance corresponding value becomes a set value. SOLUTION: When it is judged that the steering is for the change of a lane, the restraint of the steering is performed (S11). Then the existence of the resistance of a driver to the steering restraint is judged (S12). When the resistance of the driver to the steering restraint exists, a value corresponding to the time integral value from the start of the steering restraint of the resistance force of the driver is determined as a value corresponding to the degree of the resistance of the driver to the steering restraint (S13). The restraint of the steering is reduced to the extent to increase the resistance corresponding value (S14). Then whether the resistance corresponding value becomes a set value Y or not is judged (S15). When the resistance corresponding value is higher than the set value Y, the steering restraint is made zero (S16).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system capable of preventing a running vehicle from colliding with an obstacle.

[0002]

2. Description of the Related Art In order to prevent a vehicle from colliding with an obstacle such as a guardrail or another vehicle on the side or rear side when changing lanes, an obstacle on the side or rear side is provided. There has been proposed a steering device which is provided with a sensor for detecting a steering angle and performs steering suppression based on the possibility of collision between the vehicle and an obstacle.

[0003] By setting the steering restraining force so that a torque having the same magnitude as the steering input torque given by the driver and having a direction opposite to that of the steering input torque is generated, steering in a direction in which a collision with an obstacle may occur is performed. Can be suppressed.

[0004]

When steering becomes necessary to avoid collision with a forward obstacle that appears during steering suppression, the steering suppression must be released.

However, if a sensor for detecting such a forward obstacle is separately provided, the system becomes complicated.

Therefore, a value corresponding to a time integrated value of the driver's resistance from the start of steering suppression is obtained as a resistance corresponding value corresponding to the degree of the driver's resistance to the steering suppression, and the resistance corresponding value is equal to or greater than a set value. In such a case, it is considered that the steering suppression is released.

[0007] However, if such cancellation of the steering suppression is suddenly performed, the force required for the steering is sharply reduced, so that there is a problem that the behavior of the vehicle becomes unstable and the steering feeling is deteriorated.

Therefore, when canceling the steering suppression after the resistance corresponding value becomes equal to or more than the set value, it is conceivable to gradually reduce the steering suppression force.

However, since the resistance-corresponding value corresponds to the time integral value from the start of steering suppression, if the steering-suppressing force is gradually reduced after the resistance-corresponding value becomes equal to or more than the set value, the steering suppression is not performed. If the necessity of steering suddenly increases during this time, there is a problem that a delay in steering occurs because the time required for the resistance corresponding value to reach the set value is insufficient.

[0010] The priority of steering to the braking operation when changing the direction of the vehicle is different for each driver. For example, the lower the deceleration of the vehicle and the smaller the depression force of the brake pedal, the higher the steering priority. In such a driver with a small deceleration of the vehicle and a small depression force of the brake pedal, if the steering suppression force is gradually reduced after the resistance corresponding value has exceeded the set value, it is possible to avoid the obstacle in front of the driver There is a delay in the steering operation. For example, FIG.
By arranging the pylons P as shown in Fig. 7, a traveling path having a width of 3.5 m was formed. The traveling path has a width such that only one vehicle 10 can travel, as indicated by a broken line arrow in the figure, and steering is required on the way to change the course.
The distance that the course can be changed is set to 10 m. If the course change is delayed or the course change is too early, the vehicle 10 will collide with the pylon P. A vehicle 10 at a speed of 50 km / h by a plurality of drivers on the traveling path.
A running test was performed. In this case, the steering suppression force is applied, and the steering suppression force is released when the urgency of the steering is equal to or more than a certain level. FIGS. 20 and 21 show the results of the running test. In the figures, the mark △ indicates that the vehicle 10 can pass without falling down the pylon P, the mark ○ indicates that the vehicle 10 has stopped, This is the case where 10 collided. The horizontal axis in FIG. 20 is the maximum steering input torque corresponding to the steering priority, and the vertical axis is the average deceleration corresponding to the braking operation priority. The horizontal axis in FIG. 21 is the maximum steering angle corresponding to the steering priority, and the vertical axis is the average deceleration corresponding to the braking operation priority. From this running test, it was confirmed that the higher the priority of the steering operation with respect to the braking operation when changing the direction of the vehicle, the more the vehicle 10 tends to collide with the pylon P.

An object of the present invention is to provide a vehicle steering apparatus that can solve the above-mentioned problems.

[0012]

A first feature of the present invention is as follows.
In a vehicle steering device capable of suppressing steering based on the possibility of collision with an obstacle, a time integration from the start of steering suppression of the driver's resistance force as a resistance corresponding value corresponding to the degree of resistance of the driver to the steering suppression. Means for obtaining a value corresponding to the value, and means for decreasing the steering suppression force as the resistance corresponding value increases, and the steering suppression force is reduced when the resistance corresponding value reaches a set value. It is at the point where it becomes zero. According to this configuration, the steering suppression can be released only by the driver resisting the steering suppression without separately providing a sensor or the like for detecting the forward obstacle. When the resistance corresponding value reaches the set value, the steering suppression can be released, and the time required to reach the set value is shorter as the resistance corresponding value is larger, so if the necessity of steering during steering suppression increases, the steering suppression will be Can be shortened. Further, since the steering suppression force can be reduced as the resistance corresponding value increases, the steering can be suppressed with a sufficient force at the beginning of the steering suppression, and the steering suppression can be prevented from being rapidly released. As a result, it is possible to surely suppress the steering and prevent the vehicle behavior from becoming unstable or the steering feeling from being degraded. Furthermore, since the steering suppression force can be reduced to zero when the resistance corresponding value reaches the set value, even when the necessity of steering is suddenly increased during steering suppression or when the priority of steering to braking operation is high. In addition, since the driver's resistance to the steering suppression increases, the steering suppression can be quickly released, and a delay in steering can be prevented.

A second feature of the present invention is that in a vehicle steering apparatus capable of suppressing steering based on the possibility of collision with an obstacle, when a change speed of a driver's resistance to the suppression of steering is equal to or higher than a set value. Means for canceling steering suppression, means for obtaining a value corresponding to a time integral value of the driver's resistance from the start of steering suppression as a resistance corresponding value corresponding to the degree of resistance of the driver to the steering suppression, Means for gradually releasing the steering suppression when the value is equal to or greater than the set value. According to this configuration, the steering suppression can be released only by the driver resisting the steering suppression without separately providing a sensor or the like for detecting the forward obstacle. When the resistance corresponding value reaches the set value, the steering suppression can be released, and the time required to reach the set value is shorter as the resistance corresponding value is larger, so if the necessity of steering during steering suppression increases, the steering suppression will be Can be shortened. Further, since the steering suppression is gradually released when the resistance corresponding value is equal to or larger than the set value, it is possible to prevent the vehicle behavior from becoming unstable and the steering feeling from deteriorating. Since the steering suppression can be released when the changing speed of the driver's resistance to the steering suppression is equal to or higher than the set value, even when the necessity of steering increases during steering suppression or when the priority of steering to braking operation is high, By increasing the rate of change of the resistance, the suppression of steering is quickly released, and a delay in steering can be prevented.

[0014]

The first embodiment of the present invention will be described below with reference to the drawings.

First, when a vehicle is equipped with an electric power steering apparatus to which the present invention is applied and a lane change is performed, the urgency level of steering and the amount of change in steering output torque described later within a set time from the start of steering. Was determined by experiment. FIG. 1 shows the results of the experiment. In the present specification, the change acceleration of the steering output torque refers to a second-order differential value of the steering output torque with respect to time, and the change speed of the change acceleration of the steering output torque is the change acceleration of the steering output torque. It refers to the derivative over time.

The horizontal axis in FIG. 1 indicates a vehicle speed of 50 km /
The time (seconds) required to move the first 1 m when changing lanes 3.5 m in the horizontal direction at the time. The shorter the time, the higher the urgency level.

The vertical axis in FIG. 1 shows the amount of change (N · m) in the steering output torque during a set time (0.1 seconds) from the start of steering. The steering output torque changes before the turning angle of the wheel actually changes. The set time is, as described later, when standard steering is performed,
It is preferable to set as short as possible as long as the change amount of the steering output torque within the set time from the start of the steering can be associated with the urgency level of the steering.

In FIG. 1, the data of the experimental results are plotted with "●" and "△". Data a to v indicated by “●” indicate results of standard steering. Data [alpha] to [epsilon] indicated by "[Delta]" indicate the results of irregular steering. Here, the standard steering refers to steering that is performed naturally without intentionally changing the steering speed from the start to the end of the lane change. In addition, irregular steering refers to steering performed by intentionally changing the steering speed at the beginning of the lane change.

From the standard steering data a to v shown in FIG. 1, when standard steering is performed at the time of lane change, the amount of change in steering output torque within a set time from the start of steering and the urgency of steering You can see that there is a correspondence with the level. In this experiment, the steering urgency levels are classified into four levels. That is, the data a to g are “urgent” having the highest urgency level, the data h and i are “quick” having the second highest urgency level, and the data j to s are “urgent” having the third highest urgency level. "Normal", data tv
Is classified as a boundary between “normal” and “slow” having the lowest urgency level.

On the other hand, irregular steering data α to ε shown in FIG.
Thus, when irregular steering is performed at the time of lane change, it can be confirmed that there is no correspondence between the emergency level of steering and the amount of change in steering output torque within a set time from the start of steering. That is, the data α is to be classified as “quick” from the urgency level corresponding to the time required for the lane change, but since the steering is intentionally performed only immediately after the start of the lane change, It is classified as "urgent" based on the amount of change in the steering output torque within a set time from the start of steering. The data β should be classified as “quick” from the urgency level corresponding to the time required for the lane change, but the steering at normal speed is intentionally performed only immediately after the start of the lane change. Therefore, the steering output torque is classified as “normal” from the amount of change in the steering output torque within the set time from the start of steering. Although the data γ and δ should be classified as “normal” from the urgency level corresponding to the time required for the lane change, relatively quick steering is intentionally performed only immediately after the start of the lane change. Therefore, it is classified as “quick” from the amount of change in the steering output torque within a set time from the start of steering. Also, the data ε should be classified as “normal” from the urgency level corresponding to the time required for the lane change, but intentionally perform relatively gentle steering only immediately after the start of the lane change. Therefore, the steering output torque is classified into the boundary between “normal” and “slow” based on the amount of change in the steering output torque within the set time from the start of steering.

Next, when changing lanes, the urgency level of steering and the set time (0.1
The relationship between the steering output torque and the change acceleration of the steering output torque at the elapse of the second) was obtained by an experiment using a vehicle equipped with the same electric power steering device. FIG. 2 shows the results of the experiment.
Each data of the experimental result of FIG. 2 corresponds to each data of the experimental result of FIG.

The horizontal axis in FIG. 2 indicates a vehicle speed of 50 km /
In the case where a lane change of 3.5 m is made in the lateral direction, the time required to move the first 1 m is shown. The vertical axis in FIG. 2 indicates the change acceleration (N · m / s ² ) of the steering output torque at the time when 0.1 second has elapsed from the start of steering.

In FIG. 2, the data of the experimental results are shown by the results of standard steering as in FIG.
Then, the results of the irregular steering are plotted with “△”, and the data symbols a to v and α to ε correspond to the data symbols of FIG.

From the standard steering data a to v shown in FIG. 2, when the standard steering is performed at the time of lane change, the urgency level of the steering and the change acceleration of the steering output torque are associated. You can see that there is. That is, the data a to g are “urgent” having the highest urgency level, the data h and i are “quick” having the second highest urgency level,
Data j to s are "normal" with the third highest urgency level
In addition, the data t to v are classified into a boundary between “normal” and “slow” having the lowest urgency level. The change acceleration at the boundary between the urgency level “normal” and “slow” is set to zero.

On the other hand, the irregular steering data α to ε shown in FIG.
From this, it can be confirmed that when irregular steering is performed when changing lanes, the urgency level of steering does not necessarily correspond to the change acceleration of the steering output torque. That is, the data α is to be classified as “quick” from the urgency level corresponding to the time required for the lane change, but since the steering is intentionally performed only immediately after the start of the lane change, The urgency level corresponding to the change acceleration is classified into a boundary between “quick” and “normal”. In the data α, the urgency level corresponding to the amount of change in the steering output torque within the set time from the start of steering is classified as “urgent,” and the degree of the urgency level is determined by the change acceleration of the steering output torque. The urgency level corresponding to is lower. The data β should be classified as “quick” from the urgency level corresponding to the time required for the lane change, and the steering is intentionally performed at a normal speed only immediately after the start of the lane change. However, the urgency level corresponding to the change acceleration of the steering output torque is classified as “quick”. This data β
Since the urgency level corresponding to the amount of change in the steering output torque within the set time from the start of steering is classified as “normal”, the degree of the urgency level corresponds to the change acceleration of the steering output torque. The urgency level is higher. Although the data γ and δ should be classified as “normal” from the urgency level corresponding to the time required for the lane change, relatively quick steering is intentionally performed only immediately after the start of the lane change. Therefore, the urgency level corresponding to the change acceleration of the steering output torque is “normal”
And “quick” boundaries. The data γ and δ indicate that the urgency level corresponding to the change amount of the steering output torque within the set time from the start of the steering is “quick”.
The urgency level corresponding to the change acceleration of the steering output torque is lower than the urgency level. The data ε should be classified as “normal” from the urgency level corresponding to the time required for the lane change, and relatively gentle steering is intentionally performed only immediately after the start of the lane change. However, the urgency level corresponding to the change acceleration of the steering output torque is also classified as “normal”. In the data ε, the urgency level corresponding to the change amount of the steering output torque within the set time from the start of steering is classified into a boundary between “normal” and “slow”. The urgency level corresponding to the change acceleration of the steering output torque is higher.

Next, the data k, o, n, ε, r, t, u and v whose urgency level corresponding to the change acceleration of the steering output torque is close to the boundary between “normal” and “slow”. In consideration of the change speed of the change acceleration, the steering output torque at the time when the set time (0.1 second) has elapsed since the start of the steering and at the time when the set time (0.4 second) has further elapsed is calculated. The further set time is determined for each data k, o, n,
It is preferable to set as short as possible as long as the differences in the urgency levels of ε, r, t, u, and v can be identified as follows. Comparing the calculation result with the steering output torque at the lapse of 0.1 seconds from the start of steering, data k, o, and k having high urgency level corresponding to the time required for lane change
As for n and ε, as shown by arrows in FIG. 2, the steering output torque increases, and data r, t, u, and v with low urgency levels corresponding to the time required for lane change are:
As shown by the arrow in FIG. 2, the steering output torque decreases. That is, when the steering urgency level is at or near the boundary between the two urgency levels, the steering output torque at the elapse of the set time from the start of the steering increases when the steering output torque decreases, rather than decreases. Is high. The area near the boundary of the steering urgency level where this relationship holds,
In the present specification, the vicinity of the boundary of the urgency level is set, and the range from the specific boundary can be obtained by experiments.

Next, when entering a curve,
The relationship between the change amount of the steering output torque within a set time from the start of steering and the change acceleration of the steering output torque at the elapse of the set time was obtained by an experiment using a vehicle equipped with an electric power steering device. FIG. 3 shows the results of the experiment.

The horizontal axis in FIG. 3 indicates a vehicle speed of 50 km / km.
Change in steering output torque in 0.1 second from the start of steering for entering the curve when passing through a curve with a constant turning radius without deceleration (Nm)
Is shown. The vertical axis indicates the set time (0.
1 second), the change acceleration of the steering output torque (10N
· M / s ² ).

In FIG. 3, the data of the experimental results at the time of entering the curve are plotted with "●" and "□". The data indicated by “●” indicates the result of performing standard steering. Data indicated by “□” indicates the result of irregular steering. Here, the standard steering refers to steering that is performed naturally without intentionally changing the steering speed when entering a curve. In addition, irregular steering refers to steering that intentionally speeds up steering when entering a curve.

FIG. 3 also shows the relationship between the amount of change in steering output torque within a set time from the start of steering and the acceleration of change in steering output torque at the elapse of the set time when the lane is changed. Shown. As the data when the lane change is performed, data indicating that the urgency level of the steering is classified as “normal” is “○”, and data classified at the boundary between “normal” and “slow” is “△”. ".

From the standard steering data shown in FIG. 3, it can be confirmed that when standard steering is performed at the time of entering a curve, the change acceleration of the steering output torque becomes substantially zero or less. This is because the driver tries to keep the steering speed constant when trying to faithfully follow the lane at the beginning of the curve, or performs corrective steering to reduce the steering angle when the steering angle becomes excessive. Therefore, the substantially zero value of the change acceleration of the steering output torque becomes a threshold value for determining whether or not the steering purpose is going into a curve, and the threshold value can be experimentally set in advance.

The curve entry data by the standard steering is based on the change amount of the steering output torque and the change acceleration of the steering output torque, and indicates that the steering is a lane change and the urgency level is “normal”. It is smaller than the boundary with "slow" and cannot be distinguished from data whose change acceleration is equal to or less than a threshold value of substantially zero. Then, when the value of the change acceleration of the steering output torque after a set time (0.1 second) elapses is obtained, the value decreases monotonically in the case of a lane change, while it decreases or increases monotonically in the case of entering a curve. Met. The set time is set as short as possible as long as it is possible to distinguish between entering a curve and changing lanes.

On the other hand, based on the irregular steering data shown in FIG. 3, when the irregular steering is performed at the time of entering the curve, that is, when the steering wheel is intentionally sharply turned at the beginning of the steering, the steering is performed. It can be confirmed that the change acceleration of the output torque becomes larger than the substantially zero threshold value.

The curve entry data due to the irregular steering is based on the amount of change of the steering output torque and the acceleration of the change of the steering output torque. Therefore, it cannot be distinguished from those in which the change acceleration exceeds a substantially zero threshold value. Then, when the increase or decrease of the change acceleration of the steering output torque within the subsequent set time is obtained, it does not decrease when changing lanes, but decreases when entering a curve. This is because if the steering wheel is intentionally sharply turned in the case of entering a curve, the course correction steering is required thereafter. The set time is set as short as possible as long as it is possible to distinguish between entering a curve and changing lanes.

From the above, the amount of change in the steering output torque within a set time from the start of steering, the change acceleration of the steering output torque at the time when the set time has elapsed, and the subsequent setting of the steering output torque at the time when the set time has elapsed since the start of steering. The urgency level of the steering can be determined based on the increase / decrease in the time and the increase / decrease of the change acceleration of the steering output torque in the subsequent set time, and further, the purpose of the steering can be determined.

The rack and pinion type electric power steering device 1 shown in FIG.
And an output shaft 4 connected to the input shaft 2 via a torque sensor 3. The steering input torque transmitted from the input shaft 2 to the output shaft 4 is detected in time series by the torque sensor 3. Its output shaft 4
Is connected to a pinion 6, and a wheel 8 is connected to a rack 7 that meshes with the pinion 6. Thus, the steering input torque is transmitted to the rack 7 via the steering wheel H, the input shaft 2, the torque sensor 3, the output shaft 4, and the pinion 6, and the vehicle A is steered by the movement of the rack 7.

A part of the rack 7 is a ball screw 2
A gear is formed on the outer periphery of a ball nut 22 that meshes with the ball screw 21, and a drive gear 25 meshes with a gear 24 that meshes with the gear. The drive gear 25 is rotationally driven by a DC servo motor 13 which is an actuator for steering assistance and steering suppression. Thereby, the additional torque generated by the motor 13 is transmitted to the rack 7.

From the steering wheel H to the rack 7
The sum of a value obtained by multiplying the gear ratio up to the steering input torque and a value obtained by multiplying the reduction ratio from the output shaft of the motor 13 to the rack 7 by the output torque of the motor 13 corresponds to the steering output torque. In the present embodiment, the steering input torque applied by the driver is detected by the torque sensor 3 as described above as a value corresponding to the steering output torque.
The relationship between the steering input torque and the steering output torque is stored in a controller 50 described below, so that the steering input torque is associated with the steering output torque.

The torque sensor 3 is connected to a controller 50 constituted by a computer. The controller 50 includes the motor 13 and the vehicle speed detection sensor 5.
1. A plurality of obstacle detection sensors 5 attached to the vehicle A
3, 54, 55, 56 and voice alarm 52 are connected. These obstacle detection sensors 53, 54, 55,
56, for example, to detect obstacles on the left and right sides and rear left and right sides of the vehicle A, a transmitter that emits radar waves such as lasers and ultrasonic waves from the vehicle, and a receiver of the radar waves, And an amplifier for the received radar wave, and the controller 50 detects the time difference between the transmission and reception of the radar wave.
, Which can calculate the distance to the obstacle.

The controller 50 stores, as a part of a control program, a predetermined correspondence relationship between the amount of change in the steering output torque and the urgency level of the steering within a set time from the start of the steering. And a predetermined correspondence between the steering urgency level and the steering urgency level are stored. In the present embodiment, the urgency levels in the stored correspondence are four levels of “urgent”, “quick”, “normal”, and “slow” as described above.

The controller 50 performs the following steering control according to the stored control program. Less than,
The control procedure will be described with reference to flowcharts shown in FIGS.

First, the torque sensor 3 and the vehicle speed detection sensor 5
1. Start reading signals from the obstacle detection sensors 53, 54, 55, 56 in time series (step 1).

Next, a drive control current value of the motor 13 is calculated (step 2). The drive control current value of the motor 13 corresponds to the additional torque generated by the motor 13. FIG.
As shown in the relationship between the steering input torque Ti and the steering output torque To, during the steering assist, the drive control is performed such that the steering output torque To increases as the detected steering input torque Ti increases. The current value is determined. Further, the drive control current value of the motor changes depending on the detected vehicle speed. That is, in the low-speed V1 state, the steering output torque To is increased to improve the turning performance of the vehicle, and in the high-speed V2 state, the steering output torque To is reduced to improve the stability during high-speed running. The steering input torque T
The relationship between i and the steering output torque To is predetermined and stored in the controller 50.

Next, the obstacle detection sensors 53, 54,
Based on the obstacle detection signals from 55 and 56, it is determined whether an obstacle such as a nearby vehicle has been detected within a predetermined distance from the vehicle A (step 3).

If an obstacle is detected in step 3, whether or not the change in the steering output torque To corresponding to the detected steering input torque Ti within the set time exceeds the set value indicates whether or not the vehicle is traveling in a steady state. That is, it is determined whether the vehicle is traveling at a substantially constant steering angle (step 4). The set time and set value are predetermined and stored in the controller 50. Note that the steering output torque To slightly fluctuates even in a steady state due to the influence of disturbance due to irregularities on the road surface and the like and the influence of electric noise on the torque sensor 3.
Has.

When steering is started after it is determined in step 4 that the vehicle is traveling normally, the steering input torque Ti
, The change in the steering output torque To within the set time exceeds the set value. In this case, based on the sign of the steering output torque To, it is determined whether the steering start direction is the direction of the detected obstacle, that is, the vehicle A
It is determined whether there is a possibility of collision with the obstacle (step 5).

In step 5, when the steering direction is the direction of the detected obstacle, that is, when there is a possibility of collision, the steering urgency level is determined as the steering state based on the steering output torque corresponding to the detected steering input torque. A determination is made (step 6).

FIG. 7 shows a procedure for determining the urgency level of the steering.
Is shown in the flowchart of FIG. First, an urgency level corresponding to the amount of change in the steering output torque To within a set time from the start of steering, and the steering output torque T at the time when the set time has elapsed.
It is determined whether or not the urgency level corresponding to the change acceleration o matches (step 101). For this judgment,
When the set time has elapsed, the controller 50 calculates the steering output torque To at the start of steering and the steering output torque T at the elapse of the set time from the steering input torque Ti read in time series.
By calculating the difference from o, the amount of change in the steering output torque To is obtained, and the change acceleration corresponding to the second derivative of the steering output torque To at the time when the set time has elapsed is calculated.

As a result of the judgment, when the two urgency levels match, the urgency level is used as a provisional judgment result (step 102). When the two urgency levels do not match, the emergency corresponding to the change acceleration is determined. The degree level is set as a provisional determination result (step 103).

Next, it is determined whether or not the urgency level based on each provisional determination result is at or near the boundary between the two urgency levels (step 104).

As a result of the judgment, if the urgency level based on the provisional judgment result is not at or near the boundary between the two urgency levels, the urgency level based on the provisional judgment result is used as the judgment result (step 105). .

As a result of the determination, if the urgent level based on the provisional determination result is at or near the boundary between the two urgency levels, the steering output torque at the elapse of a set time (for example, 0.1 second) from the start of steering. It is determined whether To decreases within a set time (for example, 0.4 seconds) thereafter (step 106). For this determination, the controller 50
When a set time (for example, 0.1 second) has elapsed since the start of steering,
From the steering input torque Ti read in chronological order, a steering output torque To at the time when a set time (for example, 0.1 seconds) has elapsed from the start of steering is obtained. Based on the change speed of the change acceleration of the steering output torque To, the steering output torque To at the time when a set time (for example, 0.4 seconds) has elapsed thereafter is calculated.

As a result of the judgment, if the steering output torque To does not decrease within the set time thereafter, the higher urgency level of the two urgency levels is determined as the judgment result (step 107), and the subsequent setting time is set. Steering output torque To within time
Decreases, the lower urgency level of the two urgency levels is determined as the determination result (step 108).

If no obstacle within a certain distance is detected in step 3 or if the steering direction is not the direction of the detected obstacle in step 5, there is no possibility of collision with the obstacle, so there is no need to suppress steering. When the result of the determination of the steering urgency level in step 6 is “Urgent”, there is a possibility of collision with a forward obstacle, so that it is not necessary to suppress steering. In these cases, step 2
The drive control current value of the motor calculated in
To assist the steering (step 7). Thereafter, the process returns to step 1.

If it is determined in step 4 that the vehicle is not in a steady running state, that is, if the vehicle is being steered,
From the sign of the steering output torque To, it is determined whether or not the steering direction is the direction of the detected obstacle, that is, whether or not there is a possibility of collision between the vehicle A and the obstacle (step 8).

In step 8, if the steering direction is the direction of the detected obstacle, that is, if there is a possibility of collision, the steering output torque T corresponding to the detected steering input torque Ti
Based on o, it is determined whether or not a course correction steering is performed (step 9). For example, after a change due to steering to one of left and right within a set time of the steering output torque To exceeds a set value,
If the change in the steering output torque To due to steering to the other side within the set time exceeds the set value, it is determined that the steering is the course correction steering. Alternatively, the steering output torque To is integrated at predetermined time intervals by the controller 50, and the integrated value is changed after a change due to steering to one of the left and right sides within the set time exceeds the set value. If the change due to the steering to the left or right within the set time exceeds the set value, it is determined that the steering is the course correction steering. this is,
Based on the fact that it is possible to determine whether or not the purpose of the steering is the course correction steering based on the time change pattern of the steering output torque. For example, (1) of FIG. 10 shows a time change pattern of the steering output torque To when changing lanes, and the pattern is a substantially sinusoidal curve. In this case, the time point P1 at which the steering output torque To starts decreasing after steering to the left after the lane is changed to the right is the start time of the course correction steering. (2) of FIG. 10 shows a time change pattern of the steering output torque To when passing through the curve. In this case, the time point P2 at which the steering output torque To starts decreasing by steering to the left after entering the right turn curve is the start time point of the course correction steering. In any case, after the change in the steering output torque for steering to the left or right occurs, the time P at which the change in the steering output torque for steering to the left or right occurs.
1, P2 is the start point of the course correction steering. The above determination is based on recognition of the start time of the course correction steering.

If it is determined in step 9 that the steering is not the course correction steering, that is, if there is a possibility of collision, the emergency level is determined in step 6 described above.

If it is determined in step 8 that the steering direction is not the direction of the detected obstacle, or if it is determined in step 9 that the steering is path correction steering, that is, if there is no possibility of collision, steering assistance is performed in step 7.

If the result of the determination of the steering urgency level in step 6 is not the highest "emergency", it is determined whether the steering purpose is to enter a curve or to change lanes as the steering state (step 10).

FIG. 8 is a flowchart showing a procedure for determining whether the steering purpose is to enter a curve or to change lanes.

First, it is determined whether or not the determination result of the steering urgency level in step 6 is equal to or less than the boundary between "normal" and "slow", that is, the change acceleration of the steering output torque To is equal to or less than a threshold value of substantially zero. Is determined (Step 2
01).

If the change acceleration of the steering output torque To is equal to or less than the threshold value, a set time thereafter (for example, 0.1 second)
The change acceleration of the steering output torque To is calculated based on the change speed of the change acceleration of the steering output torque To when a set time (for example, 0.1 second) elapses from the start of the steering, and whether the change acceleration thereafter decreases or not. (Step 20)
2) If it decreases, it is determined that the purpose of steering is lane change (step 203), and if it does not decrease, it is determined that the purpose of steering is to enter a curve (step 204).

If the change acceleration of the steering output torque To is not equal to or smaller than the threshold value, it is determined whether the change acceleration decreases within a subsequent set time (for example, 0.1 second) (step 205). If it decreases, it is determined that the purpose of the steering is to enter the curve. If it does not decrease, it is determined that the purpose of the steering is to change lanes.

If it is determined in step 10 that the purpose of the steering is not to enter the curve but to change lanes, the steering is suppressed (step 11). The steering restraint force is
The additional torque having the opposite sign to the steering input torque Ti is
It is given by generating by. It is assumed that the absolute value of the additional torque for steering suppression changes according to the absolute value of the steering input torque Ti. In the present embodiment, an additional torque that is balanced with the steering input torque Ti is determined so that the steering output torque To becomes zero. Further, during the steering suppression, the driver is warned by voice of the danger of collision by the voice alarm 52.

Next, it is determined whether or not the driver has resistance to the steering suppression (step 12). Since the absolute value of the additional torque for steering suppression changes according to the absolute value of the steering input torque Ti, it is possible to determine the presence or absence of the driver's resistance from the steering input torque Ti and the additional torque. For example, if the steering input torque Ti and the additional torque are balanced, there is no driver resistance, and if the steering input torque Ti is larger than the additional torque, there is a driver resistance.

If there is no driver's resistance to the steering suppression in step 12, the control returns to step 1 without canceling the steering suppression.

In step 12, if there is a driver's resistance to the steering suppression, a value corresponding to the time integral value of the driver's resistance from the start of the steering suppression is obtained as a value corresponding to the degree of the driver's resistance to the steering suppression. (Step 13). In the present embodiment, a time integrated value of the steering input torque Ti from the start of steering suppression is calculated as a value corresponding to the time integrated value of the resistance of the driver.

Next, the steering suppressing force is reduced as the resistance corresponding value increases (step 14). FIG.
Is an example showing the method, the horizontal axis represents the resistance corresponding value, and the vertical axis represents the ratio K (= addition torque absolute value) of the absolute value of the additional torque corresponding to the steering suppression force to the absolute value of the steering input torque Ti. / Steering input torque absolute value). In the present embodiment, the ratio linearly decreases as the resistance corresponding value increases, but the ratio is not limited to the linear decrease, and the ratio K may be reduced as the resistance corresponding value increases.

Next, it is determined whether or not the resistance corresponding value has reached the set value Y (step 15). The set value Y is
What is necessary is just to determine so that the danger of collision with an obstacle does not increase if the release timing of the steering suppression is too early or too late. The set value Y can be changed according to the vehicle speed,
By decreasing the set value Y as the vehicle speed increases, it is possible to prevent the release timing of the steering suppression from being delayed at high speed traveling,
It is possible to prevent the release timing of the steering suppression from becoming too fast in low-speed running. In addition, the set value Y can be changed according to the characteristics of the driver, and is reduced for a driver with a relatively weak force, and increased for a driver with a relatively strong force. It is possible to prevent the timing of canceling the steering suppression from being delayed, and to prevent the timing of canceling the steering suppression from becoming too fast when a driver having a relatively strong force drives. The characteristics of the driver can be determined based on the maximum detected value of the value corresponding to the steering input torque Ti.

If the resistance-corresponding value is less than the set value Y in step 15, the control returns to step 1 without canceling the steering suppression.

If the resistance corresponding value is equal to or larger than the set value Y in step 15, the steering suppression force is set to zero and the warning by the voice alarm 52 is canceled (step 16). Thereafter, in step 7, steering assist is performed.

According to the above configuration, as shown in FIG. 11A, the time integral value of the steering input torque Ti from the start of the steering suppression, that is, the resistance corresponding value gradually increases. This necessitates steering during the steering suppression, and the driver resists the steering suppression, and the resistance corresponding value is set to the set value Y.
, The steering suppression can be released. That is, the steering suppression can be released only by the driver resisting the steering suppression without separately providing a sensor or the like for detecting a forward obstacle. This can prevent the configuration from becoming complicated. Since the time t1 at which the resistance corresponding value reaches the set value Y is shorter as the resistance corresponding value is larger, if the necessity of steering increases during steering suppression, the time until the cancellation of steering suppression can be shortened. FIG. 11 (2) shows the steering input torque Ti and the additional torque T corresponding to the steering suppression force.
The relationship with a is shown. Since the steering suppression force can be reduced as the resistance corresponding value increases, the steering can be suppressed with a sufficient force at the beginning of the steering suppression, and the steering suppression can be prevented from being rapidly released. As a result, it is possible to surely suppress the steering and prevent the vehicle behavior from becoming unstable or the steering feeling from being degraded. Furthermore, since the steering suppression force can be made zero when the resistance corresponding value reaches the set value Y, the need for steering suddenly increases during steering suppression,
Even when the steering priority for the braking operation is high, the driver's resistance to the steering suppression is increased, so that the steering suppression can be quickly released and a delay in steering can be prevented.

FIG. 13 shows a state in which the other vehicle C follows the right rear of the own vehicle A having the above-described configuration and is traveling rightward in the figure. In this state, steering for changing lanes was performed at an emergency level of "quick" or less at a position where the other vehicle C can be detected by the sensor. In this case, the additional torque Ta corresponding to the steering input torque Ti is generated as the steering suppression torque, and the steering output torque To does not change. Thereafter, the distance between the host vehicle A and the other vehicle C was increased, and steering for changing lanes was performed at an emergency level of "quick" or less at a position where the other vehicle C could not be detected by the sensor. In this case, the additional torque Ta corresponding to the steering input torque Ti is generated as the steering assist torque, and the steering is not suppressed.

FIG. 14 shows a state in which the other vehicle C follows the right rear of the host vehicle A having the above-described configuration and is traveling rightward in the figure. In this state, if the steering for changing lanes is performed at the emergency level of "emergency" in order to avoid the obstacle B ahead at the position where the other vehicle C is detected by the sensor, the steering input torque Ti is corresponded. The additional torque Ta is generated as steering assist torque, and steering is not suppressed. Further, in this state, when the steering for changing lanes is performed at an emergency level of "quick" or less in order to avoid the obstacle B in front at a position where the other vehicle C is detected by the sensor, the steering input is initially performed. An additional torque Ta (= Ti) corresponding to the torque Ti is generated as the steering suppression torque. The additional torque Ta decreases in accordance with the ratio K as the time integral value of the steering input torque Ti from the start of the steering suppression increases, and becomes zero when the time integral value reaches the set value Y, thereby suppressing the steering suppression. It is released.

FIG. 15 shows a state in which steering for entering a curve is performed at a position where the other vehicle C inside the own vehicle A having the above structure can be detected by a sensor (travels rightward in the figure). . In this case, an additional torque Ta corresponding to the steering input torque Ti is generated as a steering assist torque,
No steering suppression is provided.

FIG. 16 shows a state in which the own vehicle A having the above-mentioned structure overtakes the other vehicle C ahead and performs the course correction steering at a position where the vehicle C can be detected by the sensor. In this case, the additional torque Ta corresponding to the steering input torque Ti is generated as the steering assist torque, and the steering is not suppressed.

FIG. 17 and FIG. 18 are flowcharts showing a second embodiment of the present invention. Hereinafter, differences from the first embodiment will be described. The difference lies in the procedure from the determination of the presence or absence of the driver's resistance in the steering control to the release of the steering suppression. That is, the second embodiment is different from steps 1 to 1 in the steering control procedure of the first embodiment.
It has a steering control procedure similar to that of step 12, and includes steps 13 to 16 in the steering control procedure of the first embodiment.
However, in the second embodiment, steps 13 'to 1
6 '.

If there is no driver's resistance to the steering suppression in step 12, the control returns to step 1 without canceling the steering suppression as in the first embodiment.

In step 12, if there is a driver's resistance to the steering suppression, in this embodiment, the changing speed of the steering input torque Ti is determined as the changing speed of the driver's resistance to the steering suppression (step 13 ').

Next, it is determined whether or not the change speed of the steering input torque Ti is equal to or greater than a set value V (step 1).
4 '). The set value V may be determined so that the risk of collision with an obstacle does not increase due to too early or late release timing of the steering suppression. The setting value V can be changed in accordance with the vehicle speed, and the setting value V is reduced as the vehicle speed increases, so that the timing of releasing the steering suppression at high speed traveling can be prevented from being delayed. Can be prevented from becoming too fast. In addition, the set value V can be changed according to the characteristics of the driver, and is set smaller for a driver with a relatively weak force and increased for a driver with a relatively strong force. It is possible to prevent the timing of canceling the steering suppression from being delayed, and to prevent the timing of canceling the steering suppression from becoming too fast when a driver having a relatively strong force drives. The characteristics of the driver can be determined based on the maximum detected value of the value corresponding to the steering input torque Ti.

In step 14 ', the steering input torque T
If the change speed of i is less than the set value V, a value corresponding to a time integrated value from the start of steering suppression of the driver's resistance is obtained as a resistance corresponding value corresponding to the degree of resistance of the driver to the steering suppression, It is determined whether or not the resistance corresponding value is equal to or greater than the set value Y (step 15 '). As the resistance corresponding value, similarly to the first embodiment, the steering input torque Ti
Calculate the time integral value from the start of the steering suppression.

If the resistance corresponding value is smaller than the set value Y in step 15 ', the control returns to step 1 without canceling the steering suppression.

In step 14 ', the steering input torque T
If the change speed of i is equal to or greater than the set value V, or if the resistance corresponding value is equal to or greater than the set value Y in step 15 ', the cancellation of the steering suppression is started and the voice alarm 5
2 is also canceled (step 16 '). On this occasion,
The steering suppression is gradually released by gradually reducing the steering suppression force so that the vehicle behavior does not become unstable and the steering feeling does not deteriorate. Step 7
To assist the steering. Others are the same as the first embodiment.

According to the second embodiment, similarly to the first embodiment, the steering suppression can be released only by the driver resisting the steering suppression without separately providing a sensor for detecting a forward obstacle. When the resistance corresponding value reaches the set value Y, the steering suppression can be released, and the time until reaching the set value Y is shorter as the resistance corresponding value is larger, so if the necessity of steering during the steering suppression becomes higher, The time until the steering suppression is canceled can be shortened. Further, since the steering suppression is gradually released when the resistance corresponding value is equal to or larger than the set value Y, it is possible to prevent the vehicle behavior from becoming unstable or the steering feeling from being degraded. Since the steering suppression can be released when the changing speed of the driver's resistance to the steering suppression is equal to or higher than the set value, even when the necessity of steering increases during steering suppression or when the priority of steering to braking operation is high,
By increasing the rate of change of the resistance, the suppression of steering is quickly released, and a delay in steering can be prevented.

The present invention is not limited to the above embodiment. For example, the method of steering assistance or steering suppression is not particularly limited, and the steering assistance force or steering suppression force may be generated by hydraulic pressure. Further, the steering suppression force may be changed according to the vehicle speed or the characteristics of the driver, and may be set to a larger value as the vehicle speed is higher or the driver's force is stronger.

[0086]

According to the present invention, according to the necessity of steering during steering suppression, the vehicle behavior becomes unstable or the steering feeling becomes stable without complicating the structure, causing no delay in steering. It is possible to provide a vehicle steering apparatus capable of canceling the steering suppression without reducing the steering characteristic without being affected by the steering characteristics of the driver.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the time required to move 1 m when changing lanes and the amount of change in steering output torque during a set time.

FIG. 2 is a diagram showing the relationship between the time required to move 1 m when changing lanes and the change acceleration of the steering output torque at the elapse of a set time.

FIG. 3 shows the amount of change in steering output torque during a set time;
Diagram showing the relationship between the change in the steering output torque and the acceleration after the set time has elapsed

FIG. 4 is a diagram illustrating the configuration of a vehicle according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a steering control procedure according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a steering control procedure according to the first embodiment of the present invention.

FIG. 7 is a flowchart illustrating a steering state determination procedure according to the embodiment of the present invention.

FIG. 8 is a flowchart showing a steering state determination procedure according to the embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between a steering input torque and a steering output torque.

10A is a diagram showing a time change pattern of a steering output torque when changing lanes, and FIG. 10B is a diagram showing a time change pattern of a steering output torque when passing a curve.

11A and 11B are diagrams illustrating a relationship between a resistance corresponding value and time, and FIG. 11B is a diagram illustrating a relationship between a steering input torque, an additional torque, and time in an embodiment of the present invention.

FIG. 12 is a diagram illustrating a relationship between a resistance corresponding value and a ratio of an additional torque corresponding to a steering suppression force to a steering input torque according to the embodiment of the present invention.

FIG. 13 is an operation explanatory diagram when the steering state is determined according to the embodiment of the present invention.

FIG. 14 shows an urgency level of “emergency” in the embodiment of the present invention.
Explanatory diagram when steering state determination of whether or not is performed

FIG. 15 is an operation explanatory diagram in a case where a steering state determination of whether or not to enter a curve according to the embodiment of the present invention is performed.

FIG. 16 is an operation explanatory diagram in the case where a steering state determination of whether or not a course correction steering according to the embodiment of the present invention is performed;

FIG. 17 is a flowchart showing a steering control procedure according to the second embodiment of the present invention.

FIG. 18 is a flowchart showing a steering control procedure according to the second embodiment of the present invention.

FIG. 19 is an explanatory diagram of a running test of a vehicle.

FIG. 20 is a diagram showing the relationship between the maximum steering torque and the average deceleration, showing the results of a vehicle running test.

FIG. 21 is a diagram showing the relationship between the maximum steering angle and the average deceleration indicating the results of a vehicle running test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power steering device 3 Torque sensor 13 Motor 50 Controller

Claims (2)

[Claims] 1. A steering apparatus for a vehicle capable of suppressing steering based on the possibility of collision with an obstacle, wherein a steering resistance of the driver is controlled as a resistance corresponding value corresponding to a degree of resistance of the driver to the steering suppression. Means for obtaining a value corresponding to the time integrated value from the start, and means for reducing the steering suppression force as the resistance corresponding value increases, the steering suppression force being set by the resistance corresponding value A steering device for a vehicle, wherein the value is set to zero when the value becomes a value. 2. A steering apparatus for a vehicle capable of suppressing steering based on a possibility of collision with an obstacle, a means for canceling the steering suppression when a changing speed of a resistance of a driver against the steering suppression is equal to or higher than a set value. Means for obtaining a value corresponding to a time integrated value from the start of steering suppression of the driver's resistance as a resistance corresponding value corresponding to the degree of the driver's resistance to the steering suppression. Means for gradually releasing the steering suppression.