JP2008207775A - Steering device, automobile, and steering control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and quickly decide a change of a traveling environment on a single-sided flow of a vehicle. <P>SOLUTION: First smoothing torque Ts1 that the history of steering torque Tt is smoothed by a short time constant and second smoothing torque Ts2 that the history is smoothed by a long time constant are calculated (step S102). When a straight traveling state on a flat road is continued, the smoothing torque Ts1 and Ts2 substantially coincide with each other and a difference ¾Ts1-Ts2¾ becomes less than prescribed amount Tα ("No" in step S103), and thereby it is decided that the vehicle continues to travel on the flat road (step S104). When the vehicle transfers to a cant road, the first smoothing torque Ts1 is immediately increased and the second smoothing torque Ts2 is gradually increased, and thereby the difference ¾Ts1-Ts2¾ gradually becomes large. When the difference ¾Ts1-Ts2¾ exceeds the prescribed amount Tα ("Yes" in step S103), it is decided that the vehicle transfers to the cant road (step S105). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering apparatus, an automobile equipped with the steering apparatus, and a steering control method.

In the electric power steering, it is desired to control the assist torque so as to compensate for a situation in which the vehicle is unilaterally (deflected) due to a disturbance such as a road surface cant. For example, an average value of the steering angle when maintaining the straight traveling state is calculated, and the assist torque is controlled while detecting a neutral point necessary for maintaining the straight traveling state based on the average value. (See Patent Document 1).
JP 2006-103390 A

However, when the neutral point is detected by simple statistical processing of the steering angle as in the conventional example described in Patent Document 1 above, for example, when the traveling environment changes due to a transition from a flat road to a cant road, for example. In addition, since statistical processing including the history of the steering angle when traveling on a flat road until then is performed, it takes time until the detected neutral point approximates an accurate neutral point. It is difficult to respond smoothly to changes in the environment.
An object of the present invention is to quickly and accurately determine a change in traveling environment related to a single flow of a vehicle.

  In order to solve the above-described problem, the steering device according to the present invention detects a steering force when the vehicle is traveling straight, and the history of the detected steering force is at least longer than the first period and the first period. The transition of the traveling environment is determined according to the difference between the first steering force smoothed in the second period and the second steering force smoothed in the second period. It is characterized by that.

  In the steering device according to the present invention, the history of the steering force when traveling straight ahead is smoothed between the first period and the second period that is longer than the first period. By calculating the first steering force with high responsiveness and the second steering force with low responsiveness and determining the transition of the driving environment according to these differences, the change in the driving environment can be accurately and quickly performed. Can be determined. In other words, the first steering force alone is weak against noise, and the second steering force alone is low in follow-up performance, but the transition of the driving environment is determined according to either one of the steering forces by paying attention to the difference between the two. It is possible to make a precise and prompt determination rather than to do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< First Embodiment >>
"Constitution"
FIG. 1 is a schematic configuration of a vehicle. The front wheels 2FL and 2FR of the automobile 1 are connected to a steering wheel (hereinafter referred to as a steering wheel) 6 through a tie rod 3, a rack and pinion 4 and a steering shaft 5 in this order. 4, the front wheels 2FL and 2FR are steered around the kingpin axis.

As an electric power steering, an electric motor 8 is connected to the steering shaft 5 via a speed reducer 7 such as a worm gear, for example. The optimal assist torque is generated.
The controller 9 includes a driver torque Td detected by the torque sensor 11, a steering angle θ of the steering shaft 5 detected by the encoder 12, a vehicle speed V detected by the vehicle speed sensor 14, a yaw rate γ detected by the yaw rate sensor 15, Is entered. Although the steering angle θ of the steering shaft 5 is detected, the present invention is not limited to this, and the steering angle θ may be detected from the rotation angle of the electric motor 8. Further, the yaw rate γ is detected, but the present invention is not limited to this, and may be estimated from the wheel speed difference between the left and right wheels, or may be estimated from the vehicle speed and the steering angle by a vehicle model.

  Normally, the controller 9 has a large road reaction force, that is, a resistance when operating the handle 6 at low speeds, so the assist torque Ta is increased at this time, and the assist torque Ta is decreased at high speeds to prevent wobbling. Since this type of vehicle speed-sensitive power steering control process (hereinafter referred to as EPS control process) is a known technique, a detailed description thereof will be omitted.

Next, a driving environment determination process according to the first embodiment that is executed separately from the above-described EPS control process will be described with reference to the flowchart of FIG.
Here, it is assumed that the vehicle is traveling on a flat road as an initial state, and only the transition of the traveling environment is determined. However, the relationship with the EPS control processing is described in the fourth embodiment and later. explain.
First, in step S101, the sum of the driver torque Td and the assist torque Ta during straight traveling is calculated as the steering torque Tt, and the history is stored. Whether or not the vehicle is traveling straight ahead is determined based on whether or not the absolute value of the yaw rate (including a value corresponding to the yaw rate) γ is equal to or less than a predetermined value. For example, it is about | γ | ≦ 10 [deg / s]. Further, the assist torque Ta may be calculated from a command value by the EPS control process or a current value flowing through the electric motor 8.

  In subsequent step S102, the steering force history is smoothed with a short time constant, that is, smoothed in a short period (first period) to calculate the first smoothing torque Ts1, and the steering force history is The second smoothing torque Ts2 is calculated by performing smoothing with a long time constant, that is, smoothing with a long period (second period). This smoothing means calculating an average value or statistical processing value of the history, and the number of history to be referred to varies depending on the length of the smoothing period.

  In a succeeding step S103, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is larger than a predetermined amount Tα. The predetermined amount Tα is set to be smaller as the difference between the first period and the second period is smaller. If the determination result is | Ts1-Ts2 | ≦ Tα, the process proceeds to step S104, and it is determined that the vehicle continues to travel on a flat road, and then returns to a predetermined main program. On the other hand, if the determination result is | Ts1-Ts2 |> Tα, the process proceeds to step S105, where it is determined that the vehicle has entered the cant road, and then returns to the predetermined main program.

<Action>
Next, the operation of the first embodiment will be described with reference to the time chart of FIG.
Now, assume that the vehicle is traveling straight on a flat road. At this time, the history of the steering torque Tt is accumulated (step S101), and the history is smoothed with a short time constant, the first smoothing torque Ts1, and the second smoothing torque Ts2 with a long time constant. Are calculated (step S102).

Since the first smoothing torque Ts1 is smoothed in a short period of time, the first smoothing torque Ts1 is highly responsive to a change in torque necessary to maintain a straight traveling state and has excellent followability. On the other hand, since the second smoothing torque Ts2 is smoothed over a long period of time, it has low responsiveness to torque changes necessary to maintain a straight traveling state and is excellent in noise resistance.
If the vehicle is running straight on the flat road, the smoothing torques Ts1 and Ts2 are substantially the same, and the difference | Ts1−Ts2 | is less than the predetermined amount Tα (in step S103, “ No ”), it is determined that the vehicle continues to travel on a flat road (step S104).

When shifting from this state to a straight cant road, the torque required to maintain the straight traveling state increases. Therefore, the first smoothing torque Ts1 immediately increases, but the second smoothing torque Ts2 gradually increases, so that the difference | Ts1−Ts2 | gradually increases.
Then, when the difference | Ts1−Ts2 | exceeds a predetermined amount Tα (“Yes” in step S103), it is determined that the vehicle has shifted to a cant road (step S105).

As described above, the first smoothing torque Ts1 alone is weak against noise, and the second smoothing torque Ts2 alone is low in followability, but by focusing on the difference between the two, the road surface transitions according to one of them. Can be determined more accurately and promptly than the determination.
However, when the initial state continues to travel on a steady cant road, the determination is reversed.
That is, if the vehicle continues straight running on a flat road, the smoothing torques Ts1 and Ts2 substantially coincide with each other, and the difference | Ts1-Ts2 | is less than a predetermined amount Tα. It is determined that it continues.

When shifting from this state to a flat road, the torque required to maintain the straight traveling state decreases. Therefore, the first smoothing torque Ts1 immediately decreases, but the second smoothing torque Ts2 gradually decreases, so the difference | Ts1-Ts2 | gradually increases.
When the difference | Ts1−Ts2 | exceeds a predetermined amount Tα, it is determined that the road has returned to a flat road.

《Application example》
In the present embodiment, the history of the steering torque Tt is smoothed in two different periods, but may be smoothed in three or more different periods.
For example, processing in the case where the history of the steering torque Tt is smoothed in the first to third periods (first period <second period <third period) will be described with reference to the flowchart of FIG. FIG. 5 is a time chart thereof.

Step S111 is the same as step S101.
In subsequent step S112, the first smoothed torque Ts1 smoothed in the first period, the second smoothed torque Ts2 smoothed in the second period, and the third smoothed torque in the third period. A smoothing torque Ts3 is calculated.
In the subsequent step S113, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is greater than a predetermined amount Tβ. The predetermined amount Tβ is set to be smaller as the difference between the first period and the second period is smaller. If the determination result is | Ts1-Ts2 | ≦ Tβ, the process shifts to step S104 to determine that the vehicle continues to travel on a flat road, and then returns to a predetermined main program. On the other hand, if the determination result is | Ts1-Ts2 |> Tβ, the process proceeds to step S115.

  In step S115, it is determined whether or not the difference between the smoothing torques Ts2 and Ts3 is greater than a predetermined amount Tβ. The predetermined amount Tβ is set to be smaller as the difference between the second period and the third period is smaller. If the determination result is | Ts2-Ts3 | ≦ Tβ, the process proceeds to step S104, and it is determined that the vehicle continues to travel on a flat road, and then returns to a predetermined main program. On the other hand, if the determination result is | Ts2-Ts3 |> Tβ, the process proceeds to step S116, where it is determined that the vehicle has entered the cant road, and then returns to the predetermined main program.

As described above, the difference between the smoothing torques Ts1 and Ts2 and the difference between Ts2 and Ts3 each determine the transition of the road surface according to whether or not a predetermined condition is satisfied. can do.
Further, as shown in FIGS. 6 and 7, the same applies to the case where the history of the steering torque Tt is smoothed in the first to n-th periods, the difference between the smoothing torques Ts1 and Ts2, the difference between Ts2 and Ts3, ... The difference between Ts (n-1) and Ts (n) can be determined accurately and promptly by determining the transition of the road surface according to whether or not each satisfies a predetermined condition.

  Moreover, in said embodiment, although it is determined whether it is a flat road or a road surface cant as a transition of driving environment, it is not limited to this. In short, since it is only necessary to determine the transition of the disturbance that causes the vehicle to flow unidirectionally, any disturbance can be applied as long as it is a disturbance that acts constantly to some extent. For example, the present invention can be applied to a case where a steady cross wind is generated or a split μ road having different road surface friction coefficients between the left and right wheels continues over a long section.

"effect"
As described above, the processing in step S101 corresponds to “detection means”, the processing in step S102 corresponds to “smoothing means”, and the processing in steps S103 to S105 corresponds to “determination means”. Further, the assist torque Ta corresponds to the “auxiliary steering force”, the first smoothing torque Ts1 corresponds to the “first steering force”, and the second smoothing torque Ts2 corresponds to the “second steering force”. It corresponds.

(1) Detection means for detecting a steering force when traveling straight ahead, and a history of the steering force detected by the detection means in at least a first period and a second period longer than the first period The transition of the driving environment according to the difference between the smoothing means for smoothing and the first steering force smoothed by the smoothing means in the first period and the second steering force smoothed in the second period Determination means for determining whether or not.
Thereby, the change of the driving environment related to the single flow of the vehicle can be determined quickly and accurately.
(2) The determination means determines that the traveling environment is in a steady state when the difference is less than a predetermined amount, and the traveling environment is changed when the difference is greater than the predetermined amount.
Thereby, it can be easily determined whether the traveling environment is in a steady state or changes.

<< Second Embodiment >>
"Constitution"
First, a travel environment determination process according to the second embodiment that is executed separately from the EPS control process will be described with reference to the flowchart of FIG.
Steps S201 and S202 are the same as steps S101 and S102.
In a succeeding step S203, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is larger than a predetermined amount Tα. If the determination result is | Ts1-Ts2 | ≦ Tα, the process proceeds to step S204, and if the determination result is | Ts1-Ts2 |> Tα, the process proceeds to step S206 described later.
In step S204, it is determined that the vehicle is traveling on a flat road or a cant road and is in a steady state.

In the subsequent step S205, the second smoothing torque Ts2 is stored in the memory B, and then the process returns to the predetermined main program.
In step S206, the second smoothing torque Ts2 is stored in the memory A.
In a succeeding step S207, it is determined whether or not Ts2 stored in the memory A is larger than Ts2 stored in the memory B. When the determination result is memory A> memory B, that is, when the second smoothing torque Ts2 is increasing, the process proceeds to step S208, and it is determined that the flat road has shifted to the cant path, and then the predetermined main program Return to. On the other hand, when the determination result is memory A ≦ memory B, that is, when the second smoothing torque Ts2 is decreasing, the process proceeds to step S209, and it is determined that the transition from the cant road to the flat road is performed. Return to the main program.

<Action>
Next, the operation of the second embodiment will be described with reference to the time chart of FIG.
Now, assume that the vehicle is traveling straight on a flat road. At this time, the history of the steering torque Tt is accumulated (step S201), and the history is smoothed with a short time constant, the first smoothing torque Ts1, and the second smoothing torque Ts2 with a long time constant. Are calculated (step S202).

If the vehicle is running straight on the flat road, the smoothing torques Ts1 and Ts2 substantially coincide with each other, and the difference | Ts1−Ts2 | is equal to or less than the predetermined amount Tα (in step S203, “ No "), it is determined that the traveling environment is in a steady state regardless of the presence or absence of disturbance (step S204).
When shifting from this state to a straight cant road, the torque required to maintain the straight traveling state increases. Therefore, the first smoothing torque Ts1 immediately increases, but the second smoothing torque Ts2 gradually increases, so that the difference | Ts1−Ts2 | gradually increases.

When the difference | Ts1−Ts2 | exceeds a predetermined amount Tα (“Yes” in step S203), it is determined that the traveling environment has changed. It is determined how the road surface has changed according to the increase / decrease in the smoothing torque Ts2 at this time.
That is, when the memory A is larger than the memory B (“Yes” in step S207), the second smoothing torque Ts2 increases after the difference exceeds the predetermined amount Tα than before the predetermined amount Tα. Therefore, it is determined that the disturbance that causes the vehicle to flow in one direction has increased, that is, the vehicle has shifted from a flat road to a cant road (step S208).

If the vehicle continues straight on this steady cant road, the first smoothing torque Ts1 stops increasing first, and after a while, the second smoothing torque Ts2 stops increasing, so the difference | Ts1-Ts2 | Get smaller.
When the difference | Ts1−Ts2 | becomes equal to or less than the predetermined amount Tα (“No” in step S203), it is determined that the vehicle continues to travel on a steady cant road, that is, the traveling environment has returned to the steady state. (Step S204).

When returning from this state to the flat road again, the torque required to maintain the straight traveling state decreases. Therefore, the first smoothing torque Ts1 immediately decreases, but the second smoothing torque Ts2 gradually decreases, so the difference | Ts1-Ts2 | gradually increases.
When the difference | Ts1−Ts2 | exceeds a predetermined amount Tα (“Yes” in step S203), it is determined that the traveling environment has changed. Also at this time, it is determined how the road surface has changed in accordance with the increase / decrease in the smoothing torque Ts2.
That is, when the memory A is smaller than the memory B (“No” in step S207), the second smoothing torque Ts2 decreases after the difference exceeds the predetermined amount Tα than before the predetermined amount Tα. Therefore, it is determined that the disturbance that causes the vehicle to flow in one direction has weakened, that is, the vehicle has shifted from a cant road to a flat road (step S209).

《Application example》
In the above embodiment, the second smoothing torque Ts2 before and after the difference exceeds the predetermined amount Tα is compared, and the flat road is changed to the cant road, or the cant road is changed to the flat road. However, the present invention is not limited to this. The reason why the second smoothing torque Ts2 is selected is that it is excellent in noise resistance, and is merely a representative value. Therefore, even if the difference between the first smoothing torque Ts1 before and after the difference exceeds the predetermined amount Tα is compared, it is determined whether the flat road is changed to the canted road, or whether the cant road is changed to the flat road. Good.

In the above embodiment, the smoothing torque is compared before and after the difference exceeds the predetermined amount Tα, and the road surface transition is determined according to the increase or decrease. However, the present invention is not limited to this. .
That is, when the difference exceeds a predetermined amount Tα, the first smoothing torque Ts1 is greater than the second smoothing torque Ts2 as shown in FIG. Conversely, if the transition is from a cant road to a flat road, the first smoothing torque Ts1 is smaller than the second smoothing torque Ts2.

  Therefore, when the difference exceeds the predetermined amount Tα, if the first smoothing torque | Ts1 | is greater than the second smoothing torque | Ts2 | In other words, if the first smoothing torque | Ts1 | is smaller than the second smoothing torque | Ts2 |, it is determined that the vehicle has shifted from a flat road to a cant road. May be determined as having been weakened, that is, from a cant road to a flat road.

  In the above embodiment, it is determined that the traveling environment changes when the difference exceeds the predetermined value α, but the present invention is not limited to this. That is, even if it is determined that the traveling environment changes when the difference exceeds the predetermined value α and the amount of change in one or both of the first smoothing torque Ts1 and the second smoothing torque Ts2 exceeds the threshold value. Good. This threshold value is set so as to become smaller as the smoothing period (time constant) becomes longer.

"effect"
From the above, the processing in step S201 corresponds to “detection means”, the processing in step S202 corresponds to “smoothing means”, and the processing in steps S203 to S209 corresponds to “determination means”.
(1) The determination means compares before and after the difference exceeds a predetermined amount. If at least one of the absolute value of the first steering force and the absolute value of the second steering force is large, the determination means It is determined that the disturbance that causes the vehicle to flow unilaterally due to environmental changes has increased.
Thereby, the transition of the driving environment can be easily and accurately determined.
(2) The determination means compares before and after the difference exceeds a predetermined amount, and travels if at least one of the absolute value of the first steering force and the absolute value of the second steering force is small. It is determined that the disturbance that causes the vehicle to flow away due to environmental changes has weakened.
Thereby, the transition of the driving environment can be easily and accurately determined.

(3) When the difference exceeds a predetermined amount and the absolute value of the first steering force is greater than the absolute value of the second steering force, the determination means determines that there is a disturbance that causes the vehicle to unilaterally flow due to a change in the travel environment. Judge that it has strengthened.
Thereby, the transition of the driving environment can be easily and accurately determined.
(4) When the difference exceeds a predetermined amount and the absolute value of the first steering force is smaller than the absolute value of the second steering force, the determination means detects a disturbance that causes the vehicle to unilaterally flow due to a change in the travel environment. Judged as weakened.
Thereby, the transition of the driving environment can be easily and accurately determined.

<< Third Embodiment >>
"Constitution"
First, a travel environment determination process according to the third embodiment that is executed separately from the EPS control process will be described with reference to the flowchart of FIG.
Steps S301 and S302 are the same as steps S101 and S102.
In a succeeding step S303, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is larger than a predetermined amount Tα. If the determination result is | Ts1-Ts2 | ≦ Tα, the process proceeds to step S304. If the determination result is | Ts1-Ts2 |> Tα, the process proceeds to step S308 described later.

In step S304, the number of continuous passes of this process is counted.
In a succeeding step S305, it is determined whether or not the number of continuous passes exceeds a predetermined number.
This predetermined number corresponds to a time of 1 second or more and 1.6 times or less of the second period. First, if one second or more elapses, it will not be affected by sudden disturbance. In the experiment, the period of the steering torque during straight traveling is about 5 to 10 seconds, and it is set to 1 second on the assumption that a quarter period is required from the start of disturbance to the stabilization. In addition, 1.6 times the second period corresponds to the time required to match the target value with the low-pass filter. If the road surface takes longer than that, normal statistical processing is also supported. Because it can.

If the number of continuous passes is less than or equal to the predetermined number, the process proceeds to step S306, where the determination is suspended and the process returns to the predetermined main program. On the other hand, if the number of continuous passes exceeds the predetermined number, the process proceeds to step S307.
In step S307, the vehicle is traveling on either a flat road or a cant road, and after determining that the vehicle is in a steady state, the process returns to a predetermined main program. At this time, whether the road is a flat road or a cant road may be determined according to the magnitude of the smoothing torque. That is, if the absolute value of one of the first and second smoothing torques is equal to or less than a predetermined value (for example, 1 Nm), it is determined that the vehicle is traveling on a steady flat road, and exceeds the predetermined value. It can be determined that the vehicle is traveling on a steady cant road.

In step S308, the number of continuous passes of this process is counted.
In a succeeding step S309, it is determined whether or not the number of continuous passes exceeds a predetermined number. This predetermined number is the same as the predetermined number in step S305. If the number of continuous passes is less than or equal to the predetermined number, the process proceeds to step S306, where the determination is suspended and the process returns to the predetermined main program. On the other hand, if the number of continuous passes exceeds the predetermined number, the process proceeds to step S310.

  In step S310, after determining from the flat road to the cant road or from the cant road to the flat road, the process returns to the predetermined main program. At this time, whether the road is a flat road or a cant road may be determined according to the magnitude of the smoothing torque. That is, if the absolute value of one of the first and second smoothing torques exceeds a predetermined value (for example, 1 Nm), it is determined that the road has shifted from a flat road to a cant road. What is necessary is just to determine with having shifted from the cant road to the flat road.

<Action>
Next, the operation of the third embodiment will be described with reference to the time chart of FIG.
Now, assuming that the vehicle has shifted from a flat road to a cant road, the difference | Ts1−Ts2 | gradually increases and eventually exceeds the predetermined amount Tα (“Yes” in step S203). At this time, instead of determining that the traveling environment has changed immediately, in order to improve accuracy, the determination result is put on hold until a predetermined time has elapsed (“No” in step S309) (step S306).
Then, when a predetermined time has elapsed in this state (“Yes” in step S309), it is determined that the traveling environment has changed. At this time, it is determined how the road surface has changed according to the magnitude of the smoothing torque (step S310). That is, if the absolute value of the smooth torque is large, it is determined that the road has shifted from a flat road to a cant road.

If the vehicle continues straight on this cant road, the difference | Ts1−Ts2 | gradually decreases and eventually becomes equal to or less than the predetermined amount Tα (“No” in step S303). Also at this time, instead of immediately determining that the traveling environment is in a steady state, in order to improve accuracy, the determination result is put on hold until a predetermined time has elapsed (“No” in step S305) (step S306). ). When a predetermined time has elapsed in this state (“Yes” in step S305), it is determined that the road is a steady cant road.
After that, when shifting from a cant road to a flat road, the above is the same as the above except that the determination is reversed.

"effect"
As described above, the processing in step S301 corresponds to “detection means”, the processing in step S302 corresponds to “smoothing means”, and the processing in steps S303 to S310 corresponds to “determination means”.
(1) When the predetermined time has elapsed when the difference is less than the predetermined amount, the determination unit is in a steady state, and when the predetermined time has elapsed with the difference being greater than the predetermined amount It is determined that the driving environment has changed.
Thereby, it can be accurately determined whether the traveling environment is in a steady state or changes.

<< 4th Embodiment >>
"Constitution"
First, a travel environment determination process according to the fourth embodiment, which is executed separately from the EPS control process, will be described with reference to the flowchart of FIG. FIG. 13 is a block diagram thereof.
Steps S401 and S402 are the same as steps S101 and S102.
In a succeeding step S403, it is determined whether or not the correction flag F is reset to “0”. If the determination result is F = 0, the process proceeds to step S404. On the other hand, if a determination result is F = 1, it will transfer to step S409 mentioned later.

  In the subsequent step S404, it is determined whether or not the state of “| Ts1-Ts2 |> Tα” is continued during a predetermined period. This determination is equivalent to the processing in steps S303 to S305, S308, and S309. If the state of “| Ts1-Ts2 |> Tα” is not continued, the process proceeds to step S405. If the state of “| Ts1-Ts2 |> Tα” is continued, the process proceeds to step S407 described later. Transition.

In step S405, it is determined that the traveling environment is in a steady state, and the assist torque Ta of the EPS control process is corrected to the second smoothing torque Ts2.
In the subsequent step S406, the correction flag F is reset to “0” and then the process returns to the predetermined main program.
In step S407, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is corrected to the first smoothing torque Ts1.
In the subsequent step S408, the correction flag F is set to “1”, and then the process returns to the predetermined main program.

  On the other hand, in step S409, it is determined whether or not the state of “| Ts1-Ts2 | <Tα ′” is continued during a predetermined period. This determination is equivalent to the processing in steps S303 to S305, S308, and S309. The predetermined amount Tα ′ is a value smaller than Tα (Tα ′ <Tα), and is intended to prevent hunting. If the state of “| Ts1-Ts2 | <Tα ′” is not continued, the process proceeds to step S410. If the state of “| Ts1-Ts2 | <Tα” is continued, step S412 to be described later is performed. Migrate to

In step S410, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is corrected to the first smoothing torque Ts1.
In the subsequent step S411, the correction flag F is set to “1” and then the process returns to a predetermined main program.
In step S412, it is determined that the traveling environment is in a steady state, and the assist torque Ta of the EPS control process is corrected to the second smoothing torque Ts2.
In the subsequent step S413, the correction flag F is reset to “0” and then the process returns to the predetermined main program.

<Action>
Next, the operation of the fourth embodiment will be described with reference to the time chart of FIG.
Now, assume that the vehicle is traveling straight on a flat road, and the correction flag is reset to F = 0 (“Yes” in step S403). At this time, the smoothing torques Ts1 and Ts2 are substantially the same, and the difference | Ts1−Ts2 | is equal to or less than the predetermined amount Tα (“No” in step S404), so that the traveling environment is steady regardless of the presence or absence of disturbance. It determines with it being in a state, and outputs 2nd smoothing torque Ts2 with low responsiveness as new assist torque Ta (step S405). Therefore, the assist torque Ta having excellent noise resistance can be generated.

  When shifting from this state to a straight cant road, the difference | Ts1−Ts2 | gradually increases, and when the state exceeding the predetermined amount Tα is continued (“Yes” in step S404), the traveling environment has changed. The first smoothing torque Ts1 having high responsiveness is output as the new assist torque Ta (step S407). Therefore, it is possible to generate the assist torque Ta having excellent followability.

  At this time, since the correction flag is set to F = 1 (step S408), the difference | Ts1-Ts2 | is compared with the predetermined amount Tα ′ from the next time to determine the transition of the driving environment. The reason for switching from the predetermined amount Tα to Tα ′ is to prevent hunting, that is, to make it difficult for the correction flag set to F = 1 to be reset to F = 0, or for the correction flag to be reset to F = 0. This is to make it difficult to set F = 1.

If the vehicle continues straight on the cant road, the difference | Ts1−Ts2 | gradually decreases, and when the state of less than the predetermined amount Tα ′ is continued (“Yes” in step S409), the traveling environment returns to the steady state. And the second smoothing torque Ts2 excellent in noise resistance is output as a new assist torque Ta (step S412).
After that, when shifting from a cant road to a flat road, the above is the same as the above except that the determination is reversed.

"effect"
From the above, the processing in step S401 corresponds to “detection means”, the processing in step S402 corresponds to “smoothing means”, and the processing in steps S403 to S404, S406, S408, S409, S411, and S413 is “determination means”. ”And the processes in steps S405, S407, S410, and S412 correspond to“ control means ”.
(1) Provided with a control unit that applies an auxiliary steering force to the steering mechanism, and the control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the traveling environment is in a steady state; When the determination means determines that the traveling environment has changed, the auxiliary steering force is corrected to the first steering force.
As a result, noise resistance can be improved when the vehicle is in a steady state, and trackability can be improved when the driving environment changes.

<< 5th Embodiment >>
"Constitution"
First, a travel environment determination process according to the fifth embodiment, which is executed separately from the EPS control process, will be described with reference to the flowchart of FIG.
FIG. 15 is a diagram in which the processes in steps S407 and S410 are changed to new processes in steps S507 and S510.
In step S507, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is corrected to the average value of the smoothing torques Ts1 and Ts2.
Also in step S510, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is corrected to the average value of the smoothing torques Ts1 and Ts2.

<Action>
Next, the operation of the fifth embodiment will be described with reference to the time chart of FIG.
When the vehicle travels from a flat road to a straight cant road, the difference | Ts1−Ts2 | gradually increases, and when the state exceeding the predetermined amount Tα is continued (“Yes” in step S404), It is determined that the traveling environment has changed, and the average value of the smoothing torques Ts1 and Ts2 is output as a new assist torque Ta (step S507). Therefore, it is possible to generate the assist torque Ta that is superior in noise resistance as compared to the fourth embodiment described above.
After that, when shifting from a cant road to a flat road, the above is the same as the above except that the determination is reversed.

《Application example》
In the above embodiment, the assist torque Ta when it is determined that the traveling environment has changed is simply corrected to the average value of the smoothing torques Ts1 and Ts2. However, the present invention is not limited to this, and the smoothing torque You may correct | amend to the weighted average value of Ts1 and Ts2. According to this, both weights can be arbitrarily adjusted.

"effect"
As described above, the processes in steps S507 and S510 are included in the “determination unit”.
(1) Provided with a control unit that applies an auxiliary steering force to the steering mechanism, and the control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the traveling environment is in a steady state; When the determination means determines that the traveling environment has changed, the auxiliary steering force is corrected to an average value or a weighted average value of the first steering force and the second steering force.
Thereby, when it is a steady state, noise resistance can be improved, and when a steering environment changes, followability can be improved while maintaining noise resistance.

<< 6th Embodiment >>
"Constitution"
First, a travel environment determination process according to the sixth embodiment, which is executed separately from the EPS control process, will be described with reference to the flowchart of FIG.
In FIG. 17, the processing in steps S407 and S410 is changed to new processing in steps S607 and S610.
In step S607, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is smoothed after the content rate of the new steering torque Tt is increased in the second period in the history of the steering torque Tt. Correct to the normalized value.

In the normal moving average, as shown in FIG. 18A, the oldest data is erased every sampling period in accordance with the matrix, and new data is stored. Increasing the content rate of new data in the second period is, for example, by erasing the oldest data and the next oldest data and storing as many new data as the number erased, as shown in FIG. is there. Thus, the influence (weight) of the new data can be increased by smoothing after increasing the content rate of the new data.
Even in step S610, it is determined that the traveling environment has changed, and the assist torque Ta of the EPS control process is increased by increasing the content of the new steering torque Tt in the second period in the history of the steering torque Tt. To the smoothed value.

<Action>
Next, the operation of the sixth embodiment will be described with reference to the time chart of FIG.
When the vehicle travels from a flat road to a straight cant road, the difference | Ts1−Ts2 | gradually increases, and when the state exceeding the predetermined amount Tα is continued (“Yes” in step S404), It is determined that the traveling environment has changed, and the value smoothed after increasing the content rate of the new data in the second period is output as the new assist torque Ta (step S607). Therefore, it is possible to generate the assist torque Ta that is superior in noise resistance as compared to the fourth embodiment described above.
After that, when shifting from a cant road to a flat road, the above is the same as the above except that the determination is reversed.

"effect"
As described above, the processes of steps S607 and S610 are included in the “determination unit”.
(1) Provided with a control unit that applies an auxiliary steering force to the steering mechanism, and the control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the traveling environment is in a steady state; When the judging means judges that the driving environment has changed, the auxiliary steering force is smoothed after increasing the content ratio of the new steering force in the second period of the history of the steering force detected by the detecting means. Correct the value.
Thereby, when it is a steady state, noise resistance can be improved, and when a steering environment changes, followability can be improved while maintaining noise resistance.

<< 7th Embodiment >>
"Constitution"
First, a travel environment determination process according to the seventh embodiment, which is executed separately from the EPS control process, will be described with reference to the flowchart of FIG.
In FIG. 20, the processing in steps S404 and S409 is changed to new processing in steps S704 and S709.
In step S704, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is greater than a predetermined amount Tα. If the determination result is | Ts1-Ts2 | ≦ Tα, the process proceeds to step S405. If | Ts1-Ts2 |> Tα, the process proceeds to step S407.
In step S709, it is determined whether or not the difference between the smoothing torques Ts1 and Ts2 is smaller than a predetermined amount Tα ′. If the determination result is | Ts1-Ts2 | ≧ Tα ′, the process proceeds to step S410. If | Ts1-Ts2 | <Tα ′, the process proceeds to step S412.

<Action>
Next, the operation of the seventh embodiment will be described. FIG. 21 shows experimental data.
When the vehicle travels from a flat road to a straight cant road, the difference | Ts1-Ts2 | gradually increases and eventually exceeds the predetermined amount Tα (“Yes” in step S704). The first smoothing torque Ts1 having high responsiveness is output as the new assist torque Ta (step S407). Therefore, it is possible to generate the assist torque Ta having excellent followability.

When the second smoothing torque Ts2 having low responsiveness is used, the time required to follow the road surface change is about 4.4 seconds, but by using the first smoothing torque Ts1 having high responsiveness, The time required was shortened to about 2.5 seconds. That is, the followability to the road surface change was improved by about 43%.
After that, when shifting from a cant road to a flat road, the above is the same as the above except that the determination is reversed.

"effect"
As described above, the processes of steps S704 and S709 are included in the “determination unit”.
(1) The determination means determines that the traveling environment is in a steady state when the difference is less than a predetermined amount, and the traveling environment is changed when the difference is greater than the predetermined amount.
Thereby, it can be easily determined whether the traveling environment is in a steady state or changes.

1 is a schematic configuration of the present invention. It is a flowchart which shows the driving environment determination process of 1st Embodiment. It is a time chart which shows the effect | action of 1st Embodiment. It is a flowchart which shows a modification. It is a time chart which shows the effect | action of a modification. It is a flowchart which shows a modification. It is a time chart which shows the effect | action of a modification. It is a flowchart which shows the driving | running | working environment determination process of 2nd Embodiment. It is a time chart which shows the effect | action of 2nd Embodiment. It is a flowchart which shows the driving environment determination process of 3rd Embodiment. It is a time chart which shows the effect | action of 3rd Embodiment. It is a flowchart which shows the driving environment determination process of 4th Embodiment. It is a block diagram of a 4th embodiment. It is a time chart which shows the effect | action of 4th Embodiment. It is a flowchart which shows the driving environment determination process of 5th Embodiment. It is a time chart which shows the effect | action of 5th Embodiment. It is a flowchart which shows the driving environment determination process of 6th Embodiment. This is a history matrix. It is a time chart which shows the effect | action of 6th Embodiment. It is a flowchart which shows the driving environment determination process of 7th Embodiment. It is a time chart which shows the effect | action of 7th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car 2FL, 2FR Front wheel 3 Tie rod 4 Rack & pinion 5 Steering shaft 6 Steering wheel 7 Reducer 8 Electric motor 9 Controller 11 Torque sensor 12 Encoder 14 Vehicle speed sensor 15 Yaw rate sensor

Claims (13)

  Detection means for detecting a steering force when traveling straight ahead, and a history of the steering force detected by the detection means is smoothed at least in the first period and in a second period longer than the first period And the transition of the driving environment according to the difference between the smoothing means that performs smoothing in the first period and the second steering force that is smoothed in the second period. And a determination unit for determining the steering device.   2. The determination unit according to claim 1, wherein the determination unit determines that the traveling environment is in a steady state when the difference is less than a predetermined amount, and the traveling environment is changed when the difference is greater than the predetermined amount. Steering device.   When the predetermined time has elapsed with the difference being less than a predetermined amount, the determination means is in a steady state, and when the predetermined time has elapsed with the difference being greater than the predetermined amount The steering apparatus according to claim 1, wherein it is determined that the traveling environment has changed.   The determination means compares before and after the difference exceeds a predetermined amount, and if at least one of the absolute value of the first steering force and the absolute value of the second steering force is large, The steering apparatus according to claim 2 or 3, wherein it is determined that a disturbance that causes the vehicle to flow in one direction is increased due to a change in a traveling environment.   The determination means compares before and after the difference exceeds a predetermined amount, and if at least one of the absolute value of the first steering force and the absolute value of the second steering force is small, The steering apparatus according to any one of claims 2 to 4, wherein it is determined that a disturbance that causes the vehicle to flow in one direction due to a change in a traveling environment is weakened.   When the difference exceeds a predetermined amount and the absolute value of the first steering force is greater than the absolute value of the second steering force, the determination means is a disturbance that causes the vehicle to unilaterally flow due to a change in traveling environment. The steering apparatus according to any one of claims 2 to 5, wherein the steering device is determined to be strengthened.   If the absolute value of the first steering force is smaller than the absolute value of the second steering force when the difference exceeds a predetermined amount, the determination means is a disturbance that causes the vehicle to unilaterally flow due to a change in traveling environment. The steering device according to any one of claims 2 to 6, wherein the steering device is determined to be weakened. A control means for applying an auxiliary steering force to the steering mechanism;
The control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the driving environment is in a steady state, and the determination unit determines that the driving environment has changed. The steering device according to any one of claims 1 to 7, wherein the auxiliary steering force is corrected to the first steering force. A control means for applying an auxiliary steering force to the steering mechanism;
The control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the driving environment is in a steady state, and the determination unit determines that the driving environment has changed. The steering according to any one of claims 1 to 7, wherein the auxiliary steering force is corrected to an average value or a weighted average value of the first steering force and the second steering force. apparatus. A control means for applying an auxiliary steering force to the steering mechanism;
The control unit corrects the auxiliary steering force to the second steering force when the determination unit determines that the driving environment is in a steady state, and the determination unit determines that the driving environment has changed. In addition, the auxiliary steering force is corrected to a smoothed value after increasing the content rate of the new steering force in the second period in the history of the steering force detected by the detecting means. The steering device according to any one of claims 1 to 7.   11. The determination unit according to claim 2, wherein the determination unit changes the predetermined amount when the traveling environment changes from a steady state and when the traveling environment changes and then returns to the steady state. A steering apparatus according to claim 1. In a car equipped with a steering device,
The steering device includes a detection unit that detects a steering force when the vehicle is traveling straight ahead, and a history of the steering force detected by the detection unit at least in a first period and a second period longer than the first period. According to the difference between the smoothing means for smoothing in the period and the first steering force smoothed in the first period by the smoothing means and the second steering force smoothed in the second period, An automobile comprising: a determination unit that determines a transition of a driving environment; and a control unit that applies an auxiliary steering force to the steering mechanism and corrects the auxiliary steering force according to a determination result of the determination unit. .   The history of the steering force when traveling straight ahead is smoothed in at least two different periods, the transition of the traveling environment is determined according to the difference between the two smoothed steering forces, and according to the determined transition of the traveling environment, A steering control method, wherein an auxiliary steering force is applied to a steering mechanism.

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