JP2007168641A - Variable steering angle steering device, method thereof, and automobile mounting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a steering angle control matched to an emergency avoidance intention when an emergency avoidance operation is performed. <P>SOLUTION: Since an emergency avoidance operation detection means detects the emergency avoidance operation of a driver from the steering state of a steering wheel, and the variable steering angle control means controls to the steering output corresponding to the emergency avoidance operation, the variable steering angle steering device can perform the steering angle control matched to the emergency avoidance intention of the driver when the emergency avoidance operation is performed. Since the emergency avoidance operation of the driver is automatically assisted by only changing control contents of the steered wheel relative to the steering wheel of the driver, the driver can attain the avoidance without the need of special operation or control intervention in operating the emergency avoidance, and without being conscious of the control of the steered wheel executed in operating the emergency avoidance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable steering angle steering apparatus and method for controlling a steering gear ratio, and an automobile equipped with the variable steering angle steering apparatus.

Some conventional variable rudder angle steering devices use a gear mechanism as a speed reducer (see, for example, Patent Document 1 and Patent Document 2). These variable rudder angle steering devices control the steering angle of the steered wheels according to the vehicle speed so that the traveling state is stabilized with respect to the steering wheel steering angle.
Patent Document 3 discloses a technique for assisting emergency avoidance by using a rear wheel steering device in addition to steering the front wheels. In the technique disclosed in Patent Document 3, the driver's emergency avoidance operation is recognized by using an external sensor and the rear wheel steering angle is controlled during the emergency avoidance operation, thereby improving the turning performance of the vehicle, It stabilizes the running state of the car.

Japanese Patent No. 56-45824 Japanese Patent Laid-Open No. 2001-200666 JP-A-5-238403

  In the conventional variable steering angle steering device as shown in Patent Document 1 or Patent Document 2, in order to improve the straight traveling performance of the vehicle during high-speed traveling, the steering gear ratio is normally set so that the change in the steering angle of the steering wheel with respect to the steering wheel is small. Since it is made larger, there is a possibility that the steering amount of the steering wheel is insufficient when urgently avoiding at high speed. In order to improve the turning ability of the vehicle during low-speed driving, the steering gear ratio is set smaller than usual so that the steering angle change of the steering wheel with respect to steering is increased. There is a possibility that the steering amount becomes excessive.

Further, in Patent Document 3, in order to steer the rear wheel based on the steering angle of the front wheel, the steering angle of the rear wheel is calculated in correspondence with the steering angle of the front wheel. If the steering angle of the front wheels is inappropriate, the steering angle of the rear wheels also becomes inappropriate.
As described above, in the conventional technology, when the driver avoids the steering wheel with the intention of emergency avoidance, the steering angle output via the steering angle control may not be suitable for the intention of emergency avoidance. was there.
An object of the present invention is to perform rudder angle control suitable for avoidance intention when an emergency avoidance operation is performed.

In order to solve the above problems, the present invention provides:
A variable steering angle steering device in which a steering angle ratio of a steering output of a steered wheel with respect to a steering input from a steering wheel is variable, and the steering corresponding to an emergency avoidance operation when the steering state of the steering wheel is an emergency avoidance operation An emergency rudder angle control means for performing angle control is provided.

The present invention also provides:
A variable steering angle steering method in a variable steering angle steering apparatus in which a steering angle ratio of a steering output of a steered wheel with respect to a steering input from a steering wheel is variable, wherein whether or not the steering state of the steering wheel is an emergency avoidance operation is determined. An emergency avoidance operation detecting step for detecting, and an emergency steering angle control step for performing steering angle control corresponding to the emergency avoidance operation when an emergency avoidance operation is detected in the emergency avoidance operation detecting step. It is said.

Furthermore, the present invention provides
An automobile equipped with a variable steering angle steering device in which a steering angle ratio of an output angle of a steered wheel with respect to a steering input is variable, is installed at a driver seat front position, and is connected to a steering input portion of the variable steering angle steering device. A steering wheel connected to the vehicle body via a suspension mechanism and connected to a steering output portion of the variable steering angle steering device. A steering angle ratio variable mechanism that outputs a steering output obtained by adding a steering input from the steering wheel and an auxiliary steering input from the steering angle assist motor to the steering output unit, and drive-controlling the steering angle assist motor Thus, a variable steering angle control means for controlling the steering output, a vehicle speed detection means for detecting the own vehicle speed, and a steering state of the steering wheel are detected. A steering state detection unit; and an emergency avoidance operation determination unit that determines a driver's emergency avoidance operation based on a vehicle speed detected by the vehicle speed detection unit and a detection result of the steering state detection unit. The steering angle control means controls the output angle corresponding to the emergency avoidance operation when the emergency avoidance operation determination means determines that the emergency avoidance operation is performed by the driver.

According to the present invention, the emergency steering angle control means performs the steering angle control corresponding to the emergency avoidance operation when the steering state of the steering wheel is the emergency avoidance operation. Therefore, when the emergency avoidance operation is performed, Thus, the variable steering angle steering device that performs the steering angle control suitable for the intention to avoid can be provided.
Further, according to the present invention, whether or not the steering state of the steering wheel is an emergency avoidance operation is detected, and when the emergency avoidance operation is detected, the steering angle control corresponding to the emergency avoidance operation is performed. When the emergency avoidance operation is performed, the variable steering angle steering method can be used to perform the steering angle control suitable for the intention to avoid.

  Further, according to the present invention, the steering wheel installed at the front position of the driver's seat is connected to the steering input unit of the variable steering angle steering device, and the steering angle assist motor assists the steering input from the steering wheel. Make input. In addition, the steering wheel is connected to the vehicle body via a suspension mechanism and connected to the steering output portion of the variable steering angle steering device. The steering angle ratio variable mechanism includes a steering input from the steering wheel and a steering angle assist motor. The steering output obtained by adding the auxiliary steering input is output to the steering output unit. Further, the variable steering angle control means controls the steering output by driving and controlling the steering angle assist motor. Further, based on the vehicle speed detecting means for detecting the own vehicle speed, the steering state detecting means for detecting the steering state of the steering wheel, the own vehicle speed detected by the vehicle speed detecting means and the detection result of the steering state detecting means, Emergency avoidance operation determining means for determining an emergency avoidance operation, and when the variable steering angle control means determines that the emergency avoidance operation determination means is the driver's emergency avoidance operation, the emergency avoidance operation corresponds to the emergency avoidance operation Control the output angle. Therefore, when the driver performs an emergency avoidance operation on the steering wheel, the vehicle can perform a steering angle control that conforms to the driver's intention to avoid.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
(Constitution)
FIG. 1 is a diagram showing a configuration of a vehicle equipped with a variable steering angle steering device according to an embodiment of the present invention.
In FIG. 1, a vehicle has a vehicle speed sensor 1 that detects a vehicle speed from wheel speeds, a yaw rate sensor 2 that measures a yaw rate generated in the vehicle, and a lateral acceleration (lateral G) and a longitudinal acceleration (longitudinal G) generated in the vehicle. An acceleration sensor 3 for measuring, a driving environment detecting unit 4 configured to detect a driving environment in front of the host vehicle, an accelerator pedal sensor 5 for measuring an operation state of an accelerator pedal, and an operation of a brake pedal. Based on inputs from the brake pedal sensor 6 for measuring the state, the steering angle sensor 8 for measuring the steering angle of the steering wheel (steering wheel) 7, the planetary gear mechanism 20, the vehicle speed sensor 1, etc., the planetary gear mechanism 20 ( Detects the steering angle (front wheel steering angle) of the steering wheel (front wheels) 10FL and 10FR and the variable steering angle ratio calculation unit 9 that controls the steering angle assist motor 40). And a front wheel steering angle sensor 11 that.
Among these, the planetary gear mechanism 20 is constituted by a planetary gear mechanism.

FIG. 2 shows a schematic diagram of the planetary gear mechanism 20.
As shown in FIG. 2, the planetary gear mechanism 20 includes a first planetary gear mechanism A and a second planetary gear mechanism B.
A column upper (not shown) connected to the handle 7 is connected to the input shaft 21 of the first planetary gear mechanism A, and a column lower (not shown) connected to the steering wheel is connected to the output shaft 32 side of the second planetary gear mechanism A. The output shaft 22 of the first planetary gear mechanism A and the input shaft 31 of the second planetary gear mechanism A are connected.

  The first planetary gear mechanism A is a planetary gear mechanism having a sun gear 23, a planetary gear 24, a carrier 25 that supports the planetary gear 24, and a ring gear 26. In the first planetary gear mechanism A, the ring gear 26 is a fixed element. The second planetary gear mechanism B is composed of the same elements as the first planetary gear mechanism A, and includes a sun gear 33, a planetary gear 34, a carrier 35 that supports the planetary gear 34, and a ring gear 36. Mechanism. In the second planetary gear mechanism B, a worm wheel 38 that meshes with a worm gear 39 provided on the output shaft of the rudder angle assist motor 40 is provided on the outer periphery of the ring gear 34.

The planetary gear mechanism 20 adds the input angle θh of the input shaft 21 of the first planetary gear mechanism A and the input angle θm from the rudder angle assist motor 40 as shown in the following equation (1), The output angle θout is output from the output shaft 32 of the planetary gear mechanism B.
θout = Kh × θh + Km × θm (1)
Here, Kh is an angle transmission ratio between the input shaft 21 of the first planetary gear mechanism A and the output shaft 32 of the second planetary gear mechanism B, and Km is the output of the rudder angle assist motor 40 and the second It is an angle transmission ratio with the output shaft 32 of the planetary gear mechanism B.
The planetary gear mechanism 20 can set the steering gear ratio to an arbitrary value by controlling the rotation amount of the rudder angle assist motor 40. The amount of rotation of the steering angle assist motor 40 is controlled by the variable steering angle ratio calculation unit 9.

FIG. 3 is a diagram for explaining the operation of the planetary gear mechanism 20.
FIG. 3 (b) shows the steering with respect to steering when the steering angle assist motor 40 is driven (when the steering gear ratio is reduced) with respect to the steering state of the steering wheels 10FL and 10FR with respect to the steering shown in FIG. 3 (a). The steering state of the steering wheels 10FL and 10FR is shown.
In the state of FIG. 3B, as can be seen from the state of FIG. 3A, the steering gear angle θin of the steering wheel (or the input of the input shaft 21 of the first planetary gear mechanism A) is input by the planetary gear mechanism 20. Even if the angle θh is the same, the steering angle assist motor 40 is driven to increase the output angle θm. Therefore, the steering angle of the steered wheels 10FL and 10FR (or the output shaft 32 of the second planetary gear mechanism B) is increased. The input angle θout) increases.

FIG. 4 shows a specific configuration of the planetary gear mechanism 20.
In FIG. 4, A is the first planetary gear mechanism, B is the second planetary gear mechanism, 21 is the input shaft of the first planetary gear mechanism, specifically the column upper, 32 is the output shaft of the second planetary gear mechanism, Specifically, a column lower, 23 and 33 are sun gears of each planetary gear mechanism, 24 and 34 are planetary gears of each planetary gear mechanism, 25 and 35 are carriers of each planetary gear mechanism, and 26 and 36 are ring gears of each planetary gear mechanism. , 41 is a shaft that functions as an output shaft of the first planetary gear mechanism and an input shaft of the second planetary gear mechanism, 38 is a worm wheel, and 39 is a worm gear.

The planetary gear mechanism 20 shown in FIG. 4 has a configuration in which rollers are arranged in parallel with the respective gears to transmit torque.
The traveling environment detection unit 4 is an imaging device or a laser radar that is mounted on the front part of the vehicle body and configured by a CCD (Charge Coupled Device) or the like that detects the traveling environment in front of the host vehicle.
Under such a configuration, the variable steering angle ratio calculation unit 9 performs control processing based on the following flowchart.

5 and 6 are flowcharts showing the processing contents of the variable steering angle ratio calculation unit 9.
When the process is started, the process of step S1 in FIG. 5 is started, and the variable steering angle ratio calculation unit 9 receives the vehicle speed measured by the vehicle speed sensor 1 and the steering wheel steering angle measured by the steering angle sensor 8. Is done.
Subsequently, in step S2, the variable steering angle ratio calculation unit 9 determines whether or not the steering by the driver is a normal operation based on the vehicle speed and the steering angle input in step S1. Specifically, based on a diagram as shown in FIG. 7, it is determined whether or not the steering wheel steering by the driver is a normal operation (normal steering). Since this determination is performed based on the steering speed, the variable steering angle ratio calculation unit 9 calculates the steering speed from the change in the steering angle of the steering wheel input from the steering angle sensor 2.

As shown in FIG. 7, in the diagram, the horizontal axis is the vehicle speed, and the vertical axis is the steering speed. This diagram shows the maximum normal steering speed (solid line) in which the rate of decrease in steering speed increases with increasing vehicle speed in the region where steering speed is low, and the increase in vehicle speed in regions where steering speed is high. The maximum steering speed at the time of emergency avoidance (dotted line) in which the decrease rate of the steering speed becomes small is shown.
Here, the steering characteristic of the driver at the time of the driver's emergency avoidance operation (emergency avoidance steering), which is a premise for determining the diagram of FIG. 7, will be described. Here, the steering characteristics of the driver when the host vehicle is prevented from coming into contact with the preceding vehicle existing in front of the host vehicle will be described.

  FIG. 8 shows a scene in which the driver avoids the host vehicle 100 from coming into contact with the forward vehicle 101 existing in front of the host vehicle by an emergency avoidance operation. This scene is a scene in which the driver avoids the host vehicle 100 on the right side of the forward vehicle 101. FIG. 9 shows the steering state of the steering wheel during such an emergency avoidance operation. FIG. 9A shows a steering state of the steering wheel at each representative vehicle position, and FIG. 9B shows a history of steering speed of the steering wheel.

  In such a scene, when the host vehicle 100 approaches the forward vehicle 101 (when the traveling position of the host vehicle 100 changes from the point A to the point B shown in FIG. 8), as shown in FIG. The person steers the steering wheel greatly from the unsteered state (state A in FIG. 9A) to the right side (clockwise direction) in order to avoid contact with the front vehicle 101 (FIG. 9A). After that, when the host vehicle 100 passes by the side of the forward vehicle 101 (when the traveling position of the host vehicle 100 is a point C shown in FIG. 8), in order to reset the vehicle posture of the host vehicle 100, The steering wheel is greatly steered to the left (counterclockwise direction) by the amount steered for avoidance immediately before (state B in FIG. 9A).

In this series of steering operations, the steering speed history of the steering wheel suddenly increases from a substantially zero state as shown by a solid line in FIG. 8B, shows a peak, and then rapidly increases to the opposite side. , Again showing a peak and returning to a substantially zero state.
A dotted line shown in FIG. 9B shows a history of the steering speed of the steering wheel during a normal operation such as a lane change. Compared with the normal operation, the emergency avoidance operation as described above has a higher steering speed peak value (maximum steering speed), and further, from the urgency of avoiding contact with the forward vehicle 101. A series of steering wheel steering operations are completed in a short time. That is, the steering speed of the steering wheel rises and the steering acceleration increases.

Such characteristics of the steering speed differ depending on the host vehicle speed. Specifically, the peak value (maximum value) of the steering speed decreases as the host vehicle speed increases. Then, the tendency is stronger in the normal operation than in the emergency avoidance operation, and the rate of decrease in the peak value (maximum value) of the steering speed with respect to the increase in the host vehicle speed is increased.
Therefore, during the emergency avoidance operation, the driver's steering characteristics are unique. Based on the driver's steering characteristics, if the detected steering speed is greater than the maximum steering speed during normal operation, It can be said that the steering is likely to be caused by an emergency avoidance operation by the driver.

  For this reason, the diagram of FIG. 7 is determined by reflecting the steering characteristics of the driver at the time of the emergency avoidance operation as described above, that is, the maximum steering speed at the time of emergency avoidance of the diagram shown in FIG. Is the maximum value of the steering speed during the emergency avoidance operation as shown by the solid line in FIG. 9B, and the normal maximum steering speed of the diagram shown in FIG. 7 is as shown by the dotted line in FIG. 9B. This is the maximum steering speed during normal operation. In the diagram of FIG. 7, the region surrounded by the normal maximum steering speed line, the vehicle speed axis, and the steering speed axis is defined as the normal operation region, and the steering speed is higher than the normal maximum steering speed line (solid line). The area with a large is the emergency avoidance operation area.

  The variable rudder angle ratio calculation unit 9 has such a diagram as a table, for example, and using this diagram, the region corresponding to the vehicle speed and the steering speed input in step S1 (normal operation region or emergency operation region). Select the avoidance operation area. If the selected region is a normal operation region, it is determined that the steering by the driver is a normal operation, and if the selected region is an emergency avoidance operation region, it is determined that the steering by the driver is an emergency avoidance operation. To do. For example, when the steering speed at a certain vehicle speed is higher than the normal maximum steering speed (first predetermined value) corresponding to the vehicle speed, it is determined that steering by the driver is an emergency avoidance operation.

If the driver's steering is determined to be a normal operation, the process proceeds to step S3. If the driver's steering is not a normal operation, that is, the driver's steering is determined to be an emergency avoidance operation, the process proceeds to step S4.
Further, in place of the determination based on the steering speed of the steering wheel, or together with the determination based on the steering speed of the steering wheel, it is determined whether or not the driver's steering is an emergency avoidance operation based on a steering acceleration (steering angular acceleration) indicating the rising of the steering speed. Can do. In this case, if the detected steering acceleration of the steering wheel is greater than the maximum steering acceleration (second predetermined value) obtained during normal operation, it is determined that the driver's steering is an emergency avoidance operation.

  Further, it is possible to determine whether or not the driver's steering is an emergency avoidance operation based on the steering state history of the steering wheel. For example, when there is a change in steering, for example, when a steering speed occurs (when the steering speed rises or steering acceleration occurs), the steering speed is acquired from the time of occurrence, and so on. Whether or not the driver's steering is an emergency avoidance operation is determined from the steering speed history as the steering state history acquired in this manner. For example, the history of the steering speed within a predetermined time from the occurrence of the steering speed is compared with the history of the steering speed of the driver at the time of normal steering acquired previously, and based on the comparison result, the driver It is determined whether or not the steering is an emergency avoidance operation. For example, the steering speed history obtained within a predetermined time from the occurrence of the steering speed is somewhat deviated from the steering speed history during normal steering (the steering speed obtained during the predetermined time from the occurrence of the steering speed). If the driver's steering is an emergency avoidance operation, it is determined that the driver's steering is an emergency avoidance operation.

  In the above description, in the diagram of FIG. 7, the region where the steering speed is larger than the normal maximum steering speed is the emergency avoidance operation region. However, the normal maximum steering speed and the emergency avoidance maximum steering speed are The sandwiched area can be an emergency avoidance operation area. In this case, if the detected steering speed is greater than the maximum steering speed during emergency avoidance, the detection is treated as erroneous detection, and it is determined that the steering at that time is due to normal operation.

  In step S3, the variable steering angle ratio calculation unit 9 performs normal variable steering angle control. For example, during high speed traveling, in order to improve the straight traveling performance of the vehicle, the steering gear ratio is controlled to be larger than usual so that the change in the steering angle of the steered wheels with respect to the steering wheel is reduced. That is, the input steering angle θm from the steering angle assist motor 40 is suppressed, and the output angle θout is suppressed. Further, during low-speed traveling, in order to improve the turning ability of the vehicle, the steering gear ratio is controlled to be smaller than usual so that the steering angle change of the steered wheels with respect to the steering wheel is increased. That is, the input steering angle θm from the steering angle assist motor 40 is increased, and the output angle θout is increased.

In step S4, emergency avoidance operation control is performed. FIG. 6 is a flowchart showing the contents of the emergency avoidance operation control.
When the processing shown in FIG. 6 is started, first, in step S11, the variable steering angle ratio calculation unit 9 includes the vehicle speed measured by the vehicle speed sensor 1, the yaw rate measured by the yaw rate sensor 2, and the lateral acceleration measured by the acceleration sensor 3. (Horizontal G) is input.

  Subsequently, in step S12, the variable steering angle ratio calculation unit 9 determines that the traveling state of the host vehicle when the steered wheels are steered (especially increased steering) based on the vehicle speed, yaw rate, and lateral acceleration input in step S11. It is determined whether or not (vehicle behavior) is destabilized. That is, whether or not the traveling state of the host vehicle becomes unstable when steering by the driver determined to be the emergency avoiding operation in step S2 is permitted and the steering wheel is steered is determined. The determination is made based on the vehicle speed, yaw rate, and lateral acceleration, which are state information. For example, when the steering wheel is steered and the running state of the host vehicle exceeds the stable running limit, it is determined that the running state of the host vehicle becomes unstable.

Here, when it is determined that the traveling state of the host vehicle becomes unstable when the steering wheel is steered, the process proceeds to step S13, and it is determined that the traveling state of the host vehicle does not become unstable even when the steering wheel is steered. If so, the process proceeds to step S15.
In step S12, it is determined whether or not the traveling state of the host vehicle becomes unstable based on the vehicle speed, the yaw rate, and the lateral acceleration. However, the information indicating the vehicle state other than the vehicle speed, the yaw rate, and the lateral acceleration. Based on the above, it can be determined whether or not the traveling state of the host vehicle becomes unstable.

  In step S13, the variable rudder angle ratio calculation unit 9 suppresses steering of the steered wheels within a range in which the traveling state of the host vehicle maintains a stable state. For example, the variable rudder angle ratio calculation unit 9 controls the rudder angle assist motor 40 so as not to steer the steered wheels even when the driver steers the steering wheel. For example, it is conceivable to maintain the steering angle of the steered wheels. In this case, the variable steering angle ratio calculation unit 9 controls the input steering angle θm from the steering angle assist motor 40 to control the steering angle of the steering wheel (the first steering angle). Regardless of the input angle θh of the input shaft 21 of the one planetary gear mechanism A, the output angle θout is maintained. Then, the process proceeds to step S14. The process of step S14 will be described later.

  On the other hand, in step S <b> 15, data is input from the various sensors to the variable steering angle ratio calculation unit 9. Specifically, as data input from various sensors, the vehicle speed measured by the vehicle speed sensor 1, the yaw rate measured by the yaw rate sensor 2, the lateral acceleration (lateral G) and the longitudinal acceleration (longitudinal G) measured by the acceleration sensor 3, traveling Information on the driving environment in front of the host vehicle from the environment detection unit 4, for example, a captured image, a radar detection result, information on the operation state of the accelerator pedal measured by the accelerator pedal sensor 5, and an operation state of the brake pedal measured by the brake pedal sensor 6 And the steering angle of the steered wheel measured by the front wheel steering angle sensor 11 is input.

  Subsequently, in step S16, the variable steering angle ratio calculation unit 9 calculates the control content of the output angle θout of the output shaft 32 of the planetary gear mechanism 20 with respect to steering of the steering wheel, that is, the control content (steering control amount) of the steered wheels. The control content of the steering angle of the steered wheel with respect to the steering wheel here is different from that during normal operation (the control content of the steered wheel in step S3). Specifically, the vehicle speed, lateral acceleration, longitudinal acceleration, accelerator pedal operation state information (especially the pedal effort), brake pedal operation state information (especially the pedal effort), and steering wheel steering input in step S15. The angle is applied to the vehicle model to estimate the road surface condition (specifically, the road surface μ) of the traveling road of the own vehicle, and within the steering angle range in which the own vehicle does not cause skidding under the estimated road surface condition. The control details of the steered wheels are calculated so that That is, the variable steering angle ratio calculation unit 9 calculates the steering angle range (control content) of the steered wheels within a range in which the traveling state of the host vehicle maintains a stable state based on the current traveling state of the host vehicle.

On the other hand, when the driver is performing an emergency avoidance operation by steering on an obstacle ahead of the host vehicle, the steering angle of the steered wheels for avoiding steering with respect to the obstacle is calculated with priority. This calculation is performed according to the following procedure.
First, based on the information on the traveling environment in front of the host vehicle input in step S15, an obstacle (avoidance target) in front of the host vehicle to be avoided by the emergency avoidance operation, for example, a stopped vehicle is specified. . Then, the variable steering angle ratio calculation unit 9 refers to the identified obstacle and the steering angle of the steering wheel measured by the steering angle sensor 8, and calculates the avoidance path as the control content of the steering wheel.

Specifically, the variable steering angle ratio calculation unit 9 determines the avoidance direction based on the steering angle of the steering wheel measured by the steering angle sensor 8. That is, if it is determined that the driver is steering to the right based on the steering angle of the steering wheel, the avoidance direction is determined to the right, and the driver is steering to the left based on the steering angle of the steering wheel. If it is determined, the avoidance direction is determined on the left side.
Furthermore, the variable steering angle ratio calculation unit 9 calculates the relative position and relative speed between the host vehicle and the obstacle as the relative relationship between the host vehicle and the avoidance target. Based on the calculated relative position and relative speed and the determined avoidance direction, the variable steering angle ratio calculation unit 9 calculates an avoidance route appropriate for the host vehicle to avoid an obstacle. For example, based on information such as relative position, relative speed, and vehicle width of the host vehicle, an avoidance route that can be avoided without causing the host vehicle to contact at least an obstacle is calculated.

  Then, the variable steering angle ratio calculation unit 9 finally sets the avoidance route within a range in which the traveling state of the host vehicle maintains a stable state based on the traveling state of the host vehicle based on the avoidance route thus determined. decide. That is, the variable steering angle ratio calculation unit 9 performs the vehicle speed, lateral acceleration, longitudinal acceleration, accelerator pedal operation state input in step S15 in the same manner as described above when there is no obstacle ahead of the host vehicle. Information (especially the pedal effort), brake pedal operation state information (especially the pedal effort), and the steering angle of the steered wheels are applied to the vehicle model to estimate the road surface condition of the vehicle's running road, and the estimated road surface The range of the steering angle of the steered wheels in which the vehicle does not skid under the state is calculated. That is, the variable steering angle ratio calculation unit 9 calculates the range of the steering angle of the steered wheels within a range in which the traveling state of the host vehicle maintains a stable state based on the current traveling state of the host vehicle. Then, with reference to the avoidance route, an avoidance route that satisfies the calculated steering angle range of the steered wheels is finally calculated.

  The control details of the steered wheels when the driver is performing an emergency avoidance operation on the obstacle described above assists the driver's steering until the own vehicle completes the obstacle avoidance (so-called Some assistance may be used, or assistance provided when the driver is not performing steering for avoidance (so-called complete assistance). In the latter case, the control details of the steered wheels are calculated (control of the steered wheels is started) with at least the driver starting the emergency avoidance operation as a trigger. In this case, the avoidance direction for the obstacle is determined based on at least the steering direction (right side or left side) in which the driver has started the emergency avoidance operation, and the avoidance route is calculated based on the direction.

In addition, since the technology for estimating the road surface state of the traveling road of the host vehicle has already been implemented in functions such as four-wheel braking force control and four-wheel steering control, the road surface state already implemented in this embodiment as well. Estimation techniques can be used.
Moreover, although the obstruction is detected as a driving environment ahead of the own vehicle, it is not limited to this. For example, the road shape (for example, a curved road) and the number of lanes can be detected as the traveling environment in front of the host vehicle. For example, in this case, the avoidance route is calculated based on the road shape and the number of driving lanes.

  Subsequently, in step S17, the variable steering angle ratio calculation unit 9 becomes the steered wheel control content calculated in step S16 (including the steered wheel control content for passing through the finally calculated avoidance route). Thus, the steered wheel is controlled. That is, the variable steering angle ratio calculation unit 9 controls the steering angle assist motor 40 by outputting a control signal so that the control content calculated in step S16 is obtained.

For example, when the driver's emergency avoidance operation is not performed on an obstacle ahead of the host vehicle, the variable steering angle ratio calculation unit 9 has a greater change in the steering angle of the steered wheels with respect to steering the steering wheel than during normal operation. In other words, the steering angle assist motor 40 is controlled so that the steering gear ratio becomes small.
Further, the variable steering angle ratio calculation unit 9 changes the steering angle of the steered wheels with respect to the steering wheel depending on the case when the driver is performing an emergency avoidance operation on an obstacle ahead of the host vehicle even when traveling at high speed. The steering angle assist motor 40 is controlled so as to be larger than that during normal control, that is, so that the steering gear ratio is reduced. That is, the variable rudder angle ratio calculation unit 9 increases the input rudder angle θm from the rudder angle assist motor 40 compared to that during normal control to increase the output angle θout.

  The variable steering angle ratio calculation unit 9 also changes the steering angle of the steered wheels relative to the steering wheel when the driver is performing an emergency avoidance operation on an obstacle ahead of the host vehicle, even during low-speed driving. The steering angle assist motor 40 is controlled so as to be smaller than that during normal control, that is, so that the steering gear ratio is increased. That is, the variable steering angle ratio calculation unit 9 suppresses the output steering angle θout by suppressing the input steering angle θm from the steering angle assist motor 40 as compared with the normal control. In this way, at the time of emergency avoidance operation, the control content of the steering wheel at the time of normal steering is changed to the control content corresponding to the emergency avoidance operation. Reduce the amount of ring cutting. Then, the process proceeds to step S14.

In step S14, the variable steering angle ratio calculation unit 9 determines whether or not the emergency avoidance operation by the driver has ended. For example, the variable rudder angle ratio calculation unit 9 determines that if the steering speed is equal to or lower than the normal maximum steering speed for a certain time, if the traveling environment detection unit 4 stops detecting an obstacle for a certain time, the yaw rate is When it becomes 0, or when the steering wheel is not steered for a certain period of time, it is determined that the driver's emergency avoidance operation has ended.
Here, when it is determined that the driver's emergency avoidance operation has ended, the process returns to the process shown in FIG. 4 and the processes from step S1 are performed again. Moreover, when it determines with the driver | operator's emergency avoidance operation having not been complete | finished, the process from step S11 is implemented again.

(Operation)
Next, the operation of the variable steering angle steering device will be described.
When the steering operation of the driver is a normal operation, normal variable steering angle control is performed according to the vehicle speed. For example, during high-speed traveling, the steering angle assist motor 40 is controlled so that the change in the steering angle of the steered wheels with respect to the steering wheel is small. Thereby, the straight traveling property of the vehicle is enhanced. Further, during low-speed traveling, the steering angle assist motor 40 is controlled so that the steering angle change of the steered wheels with respect to the steering wheel is increased. As a result, the turning ability of the vehicle is improved.

When the steering speed of the driver's steering wheel increases to some extent, that is, when the steering speed of the steering wheel exceeds the normal maximum steering speed, it is determined that the steering operation is an emergency avoidance operation (steps S2 and S4). .
When it is determined that the operation is an emergency avoidance operation, if the steering wheel is further steered based on the vehicle speed, the yaw rate, and the lateral acceleration, it is determined that the traveling state of the host vehicle becomes unstable. (Steps S11 to S13).

On the other hand, when it is determined that the operation is an emergency avoidance operation, if it is determined that the traveling state of the host vehicle does not become unstable based on the vehicle speed, the yaw rate, and the lateral acceleration, even if steering of the steering wheel is permitted, various sensor inputs Based on the above, the control details of the steered wheels are calculated (step S12, step S14 to step S17).
Specifically, when the driver's emergency avoidance operation is not performed on an obstacle ahead of the host vehicle, a range in which the traveling state of the host vehicle maintains a stable state, such as preventing a side slip of the host vehicle ( The control details of the steered wheels are calculated within the limit of stable travel, and the steering angle assist motor 40 is controlled so as to be the control details of the steered wheels.

  In addition, when the driver is performing an emergency avoidance operation on an obstacle in front of the host vehicle, an optimum avoidance route is calculated for the obstacle, while the host vehicle is prevented from slipping. The steering angle range of the steered wheels is calculated within a range in which the traveling state of the vehicle maintains a stable state, and an optimum avoidance route is finally calculated based on the calculated steering angle range. At this time, if there is a driver's steering until the avoidance of the obstacle is completed, an avoidance route for assisting the steering is calculated, or if the driver's steering disappears before the avoidance is completed, An avoidance route that can complete the avoidance is calculated. Then, the steering angle assist motor 40 is controlled so that the calculated avoidance route (control details of the steered wheels) is obtained.

(Function)
Next, the operation of the variable steering angle steering device will be described.
If the driver steers the steering wheel and the steering speed is higher than the normal maximum steering speed corresponding to the vehicle speed at that time, it is determined that the steering of the steering wheel is an emergency avoidance operation, and the vehicle does not skid. The control details of the steered wheels are calculated within the range in which the stable running state is maintained, and the steered wheels are controlled with respect to the steering wheel.
Further, even if it is determined that the steering operation is an emergency avoidance operation, if it is predicted that the traveling state of the host vehicle will become unstable if the steering wheel is further steered, steering of the steering wheel is suppressed. . For example, even if the driver steers the steering wheel, the steering wheel is not steered.
In addition, even when driving at high speeds, if necessary, the change in the steering angle of the steered wheels with respect to the steering wheel is larger than that during normal control. Make it smaller than during normal control.

  FIG. 10 shows a relative relationship between the host vehicle 100 and the stopped vehicle (obstacle) 101 when the driver steers the steering wheel and performs an emergency avoidance operation. FIG. 10A is a case where the host vehicle 100 is traveling at a low speed, and FIG. 10B is a case where the host vehicle 100 is traveling at a high speed. 10 (a) and 10 (b), the travel locus of the vehicle 100 to which the present invention is applied is indicated by a solid line, and the travel locus of the conventional vehicle 100 is indicated by a dotted line.

  As shown by a dotted line in FIG. 10A, the change in the steering angle of the steered wheel with respect to the steering wheel is increased in order to improve the turning ability of the vehicle 100 during low-speed driving as usual. Is permitted, the traveling state of the vehicle 100 becomes unstable, and the vehicle 100 may come into contact with the stopped vehicle 101. On the other hand, by applying the present invention, as shown by a solid line in FIG. 10A, the host vehicle 100 contacts the stopped vehicle 101 so that the traveling state of the host vehicle 100 can be maintained in a stable state. By controlling the steered wheel based on the avoidance route (control content for suppressing the steering angle change of the steered wheel with respect to the steering wheel), the vehicle 100 does not become unstable even during low speed travel. It is possible to avoid contact with the stopped vehicle 101.

  In addition, as shown by a dotted line in FIG. 10B, in order to improve the straight traveling performance of the vehicle 100 at the time of high speed driving as usual, the change in the steering angle of the steered wheel with respect to the steering wheel is reduced, so that the driver can avoid emergency Even if the operation is performed, the vehicle 100 may come into contact with the stopped vehicle 101 because a large turnability cannot be obtained. On the other hand, by applying the present invention, as shown by a solid line in FIG. 10B, the host vehicle 100 does not contact the stopped vehicle 101 so that the traveling state of the host vehicle can be maintained in a stable state. By controlling the steered wheel based on such an avoidance route (the control content that increases the steering angle change of the steered wheel with respect to the steering wheel), the vehicle 100 does not become unstable even during high-speed travel. Contact with the stopped vehicle 101 can be avoided.

In the description of the embodiment, the planetary gear mechanism 20 realizes a steering angle ratio variable mechanism, the variable steering angle ratio calculation unit 9 realizes variable steering angle control means, the vehicle speed sensor 1, the steering angle. The process of step S2 of the sensor 8 and the variable steering angle ratio calculation unit 9 realizes an emergency avoidance operation detection means. Further, the vehicle speed sensor 1 realizes a vehicle speed detection means, the steering angle sensor 8 realizes a steering state detection means, and the process of step S2 of the variable steering angle ratio calculation unit 9 realizes an emergency avoidance operation determination means. is doing. The vehicle speed sensor 1, the yaw rate sensor 2, and the acceleration sensor 3 realize vehicle traveling state detection means, the traveling environment detection unit 4 realizes traveling environment detection means, and the step of the variable steering angle ratio calculation unit 9. The process of S16 realizes an avoidance route determination unit. Further, the vehicle speed sensor 1, the steering angle sensor 8, and the variable steering angle ratio calculation unit 9 realize an emergency steering angle control means.
The input unit to which the steering wheel is connected is the input shaft (column upper) 21 or the carrier 25 of the first planetary gear mechanism A, and the input unit to which the steering angle assist motor is connected is the worm wheel 38, The output unit connected to the steered wheels is the output shaft (column lower) 32 or the carrier 35 of the second planetary gear mechanism B.

(Effect of embodiment)
(1) The emergency avoidance operation detecting means detects the driver's emergency avoidance operation from the steering state of the steering wheel, and the variable steering angle control means controls the steering output corresponding to the emergency avoidance operation. The steering angle control suitable for the driver's intention to avoid can be performed. In addition, since the driver's emergency avoidance operation is automatically assisted only by changing the control details of the steering wheel for the steering of the driver's steering wheel, the driver can perform special operations and control intervention during the emergency avoidance operation. However, the avoidance can be achieved without being aware of the control of the steered wheels that is being performed during the emergency avoidance operation.

(2) The vehicle speed detection means detects the vehicle speed, the steering state detection means detects the steering state of the steering wheel, and based on the detection results, whether or not the emergency avoidance operation determination means is the driver's emergency avoidance Therefore, the driver's emergency avoidance operation is detected from information generally detected in the automobile (especially, the steering state of the steering wheel directly related to the avoidance operation and the vehicle speed that has a strong influence on the steering state). Steering angle control suitable for the intention to avoid this can be performed.

(3) The vehicle traveling state detection means detects the traveling state of the host vehicle, and based on the detection result, the variable steering angle control unit responds to the emergency avoidance operation within a range where the traveling state of the host vehicle is maintained in a stable state. Therefore, appropriate control can be performed without destabilizing the traveling state of the host vehicle by the control of the steering wheel with respect to the steering wheel during the emergency avoidance operation by the driver.

(4) The variable steering angle control means increases the steering angle of the steered wheels within a range in which the host vehicle can maintain a stable traveling state. Therefore, the turning ability of the vehicle at the time of avoidance can be improved while ensuring stable traveling of the host vehicle.
(5) Steering wheels are controlled within a range in which the traveling state of the host vehicle can maintain a stable state using the side slip state of the host vehicle as an index. Thus, it is possible to control the steering output corresponding to the emergency avoidance operation while referring to the side skid state of the vehicle, which is a main factor that destabilizes the vehicle in the avoidance operation.

(6) The travel environment detection means detects the travel environment in front of the host vehicle (for example, an obstacle that is a target of the driver's emergency avoidance operation), and the avoidance route determination means responds to the driver's emergency avoidance operation. The avoidance route is determined based on the traveling environment, and the variable steering angle control means controls the steered wheels so as to follow the determined avoidance route. As a result, even when the driver cannot perform an appropriate emergency avoidance operation, obstacles can be avoided at a higher rate. In addition, even if the driver's steering input disappears before the avoidance is completed, the steering angle is controlled along the determined avoidance route, so there is no psychological margin for emergency avoidance, etc. Even if the driver cannot steer, obstacles can be avoided more reliably.

(7) The travel environment detection means detects an obstacle as the travel environment, and the avoidance route determination means determines the avoidance route based on the distance and relative speed between the obstacle and the host vehicle. Thereby, an avoidance route can be set more appropriately, for example, considering the driver's feeling.
(8) Since the emergency avoidance operation detecting means detects the emergency avoidance operation based on the first predetermined value set for the steering speed (angular speed) of the steering wheel, it is clearly determined depending on the difference in the steering speed from the normal time. Emergency avoidance steering can be detected.

(9) The emergency avoidance operation detecting means detects the emergency avoidance operation based on the first predetermined value set for the steering speed of the steering wheel, and decreases the predetermined value as the host vehicle speed increases. The emergency avoidance operation can be detected more accurately based on the criteria adapted to the traveling state.
(10) Since the emergency avoidance operation detecting means detects the emergency avoidance operation based on the second predetermined value set for the steering angular acceleration of the steering wheel, the emergency avoidance operation can be detected at the rising of the steering input. The steering output corresponding to emergency avoidance can be controlled.

(11) Since the emergency steering angle control means performs the steering angle control corresponding to the emergency avoidance operation when the steering state of the steering wheel is the emergency avoidance operation, the intention of avoiding when the emergency avoidance operation is performed Can be controlled.
(12) It is detected whether or not the steering state of the steering wheel is an emergency avoidance operation. When the emergency avoidance operation is detected, the steering angle control corresponding to the emergency avoidance operation is performed. When performed, a variable steering angle steering method that performs steering angle control suitable for avoidance intention can be achieved.

(13) In the automobile according to the present invention, the steering wheel installed at the front position of the driver's seat is connected to the steering input unit of the variable steering angle steering device, and the steering angle assist motor is operated by the steering input from the steering wheel. Auxiliary steering input is performed. In addition, the steering wheel is connected to the vehicle body via a suspension mechanism and connected to the steering output portion of the variable steering angle steering device. The steering angle ratio variable mechanism includes a steering input from the steering wheel and a steering angle assist motor. The steering output obtained by adding the auxiliary steering input is output to the steering output unit. Further, the variable steering angle control means controls the steering output by driving and controlling the steering angle assist motor. The vehicle according to the present invention includes a vehicle speed detecting means for detecting the own vehicle speed, a steering state detecting means for detecting the steering state of the steering wheel, the own vehicle speed detected by the vehicle speed detecting means, and a detection result of the steering state detecting means. And an emergency avoidance operation determination means for determining the driver's emergency avoidance operation, and the variable steering angle control means determines that the emergency avoidance operation determination means is the driver's emergency avoidance operation, The output angle corresponding to the emergency avoidance operation is controlled. Therefore, when the driver performs an emergency avoidance operation on the steering wheel, the vehicle can perform a steering angle control that conforms to the driver's intention to avoid.

It is a figure which shows the structure of the vehicle of embodiment of this invention. It is a figure which shows the structure of the planetary gear mechanism mounted in the said vehicle. It is the figure used for description of operation | movement of the said planetary gear mechanism. It is sectional drawing which shows the specific structure of the said planetary gear mechanism. It is a flowchart which shows the processing content of the variable steering angle ratio calculating unit with which the said vehicle is mounted. It is a flowchart which shows the content of the emergency avoidance operation time control by the said variable steering angle ratio calculating unit. The figure used by determination of emergency avoidance operation is shown. It is a figure which shows the driving | running | working scene at the time of emergency avoidance operation. It is a figure which shows the driver | operator's steering characteristic etc. at the time of emergency avoidance operation. It is the figure used for description of an effect | action of a variable steering angle steering apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Vehicle speed sensor, 2 Yaw rate sensor, 3 Acceleration sensor, 4 Driving environment detection part, 5 Accelerator pedal sensor, 6 Brake pedal sensor, 7 Steering wheel, 8 Steering angle sensor, 9 Variable steering angle ratio calculating unit, 10FL, 10FR Steering wheel ( Front wheel), 11 front wheel rudder angle sensor, 20 planetary gear mechanism, 21 input shaft, 32 output shaft, 38 worm wheel, 40 rudder angle assist motor

Claims (13)

A steering wheel is connected to the steering input unit, a steering angle assist motor is connected to the motor input unit, a steering wheel is connected to the steering output unit, and steering input from the steering wheel and auxiliary steering from the steering angle assist motor are connected. A variable steering angle ratio variable mechanism that outputs a steering output obtained by adding the input to the steering output unit, and a variable steering angle control unit that controls the steering output by driving and controlling the steering angle assist motor. A steering angle steering device,
Based on the steering state of the steering wheel, comprising an emergency avoidance operation detection means for detecting the driver's emergency avoidance operation,
The variable rudder angle control unit controls the steering output corresponding to the emergency avoidance operation when the emergency avoidance operation detection unit detects the driver's emergency avoidance operation. The emergency avoidance operation detection means includes
Vehicle speed detecting means for detecting the own vehicle speed;
Steering state detecting means for detecting the steering state of the steering wheel;
An emergency avoidance operation determination means for determining whether the driver's emergency avoidance operation is based on the own vehicle speed detected by the vehicle speed detection means and the detection result of the steering state detection means;
The variable steering angle steering device according to claim 1, comprising: Vehicle running state detecting means for detecting the running state of the host vehicle,
The variable rudder angle control means controls the steering output corresponding to the emergency avoidance operation within a range in which the running state of the host vehicle maintains a stable state based on the detection result of the vehicle running state detecting unit. The variable steering angle steering apparatus according to claim 1 or 2, characterized in that it is characterized in that:   The variable rudder angle control means, based on the detection result of the vehicle travel state detection means, outputs the steering output within a range in which the travel state of the host vehicle maintains a stable state during the emergency avoidance operation. The variable steering angle steering device according to claim 3, wherein the steering angle steering device is increased.   The variable steering angle steering device according to claim 3 or 4, wherein the vehicle running state detection means detects a side slip state of the host vehicle.   A traveling environment detection unit that detects a traveling environment in front of the host vehicle; and an avoidance route determination unit that determines an avoidance route according to the driver's emergency avoidance operation based on the traveling environment detected by the traveling environment detection unit; The variable rudder angle control means controls the steering output along the avoidance route determined by the avoidance route determination means to the steering output according to any one of claims 1 to 5. Variable steering angle steering device.   The traveling environment detection means detects an obstacle that is an object of a driver's emergency avoidance operation as the traveling environment, and the avoidance route determination means has at least a relative speed or a distance between the obstacle and the host vehicle. The variable steering angle steering apparatus according to claim 6, wherein the avoidance route is determined based on one of them.   8. The emergency avoidance operation detecting means detects a driver's steering as an emergency avoidance operation when the steering speed of the steering wheel is higher than a first predetermined value. 9. The variable steering angle steering device according to item.   The emergency avoidance operation determination means determines that the driver's steering is an emergency avoidance operation when the steering speed of the steering wheel is greater than a first predetermined value, and the vehicle speed detected by the vehicle speed detection means 3. The variable steering angle steering apparatus according to claim 2, wherein the first predetermined value is reduced as the value increases.   10. The emergency avoidance operation detecting means detects a driver's steering as an emergency avoidance operation when a steering angular acceleration of the steering wheel is larger than a second predetermined value. The variable steering angle steering device according to Item 1. A variable steering angle steering device in which a steering angle ratio of a steering output of a steered wheel with respect to a steering input from a steering wheel is variable,
A variable steering angle steering device comprising emergency steering angle control means for performing steering angle control corresponding to an emergency avoidance operation when the steering state of the steering wheel is an emergency avoidance operation. A variable steering angle steering method in a variable steering angle steering device in which a steering angle ratio of a steering output of a steered wheel with respect to a steering input from a steering wheel is variable,
An emergency avoidance operation detecting step for detecting whether or not the steering state of the steering wheel is an emergency avoidance operation;
In the emergency avoidance operation detection step, when an emergency avoidance operation is detected, an emergency rudder angle control step for performing steering angle control corresponding to the emergency avoidance operation;
A variable rudder angle steering method comprising: A vehicle equipped with a variable steering angle steering device in which a steering angle ratio of an output angle of a steering wheel to a steering input is variable,
A steering wheel installed at a driver's seat front position and connected to a steering input portion of the variable steering angle steering device;
A steering angle assist motor that performs auxiliary steering input with respect to steering input from the steering wheel;
Steering wheels connected to the vehicle body via a suspension mechanism and connected to a steering output portion of the variable steering angle steering device;
A steering angle ratio variable mechanism that outputs a steering output obtained by adding a steering input from the steering wheel and an auxiliary steering input from the steering angle assist motor to the steering output unit;
Variable steering angle control means for controlling the steering output by controlling the steering angle assist motor;
Vehicle speed detecting means for detecting the own vehicle speed;
Steering state detecting means for detecting the steering state of the steering wheel;
An emergency avoidance operation determination means for determining an emergency avoidance operation of the driver based on the vehicle speed detected by the vehicle speed detection means and the detection result of the steering state detection means; When the emergency avoidance operation determining means determines that the driver's emergency avoidance operation is performed, the vehicle is controlled to the output angle corresponding to the emergency avoidance operation.

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