JP2012016964A - Steering control apparatus for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering control apparatus for a vehicle that avoids a steering operation which is not intended by a driver and that does not give a sense of incongruity to the driver.SOLUTION: The steering control apparatus for the vehicle includes: a turning device for turning a steering control wheel according to a steering state of a steering wheel steered by the driver; and a reaction-force giving device for giving a steering reaction force to the steering wheel. When the apparatus detects the state that the steering operation which is not intended by the driver occurs, the steering reaction force is given so that a variation of a steering angle is controlled.

Description

  The present invention relates to a vehicle steering control device that steers a steered wheel by an actuator in accordance with a steering operation of a driver.

  Conventionally, Patent Document 1 discloses a steering that is steered by a driver, a steering mechanism that drives a steered wheel according to a steering state such as a steering angle and a steering direction of the steering, and steering with respect to the steering. 2. Description of the Related Art A vehicle steering control device including a reaction force applying unit that applies a reaction force is known.

JP 2006-205953 A

However, in the technique described in Patent Document 1, even when unintended steering steering is performed due to driver's carelessness or the like, the steering mechanism steers the steered wheels according to the steering. Therefore, there has been a problem that unintended vehicle behavior changes occur and give the driver a sense of incongruity.
The present invention has been made paying attention to the above problems, and an object thereof is to provide a vehicle steering control device that avoids a steering operation unintended by the driver and does not give the driver a sense of incongruity.

  In order to achieve the above object, in the present invention, a steering means for turning a steered wheel according to a steering state of a steering steered by a driver, a reaction force applying means for applying a steering reaction force to the steering, When a situation in which a steering operation unintended by the driver occurs is detected in the vehicle steering control device having the above, a steering reaction force is applied so as to suppress a change in the steering angle.

  Therefore, it is possible to suppress a change in the steering angle that is not intended by the driver, and it is possible to suppress a driver's uncomfortable feeling by suppressing a change in vehicle behavior that is not intended by the driver.

1 is a configuration diagram of a steer-by-wire system to which a vehicle steering control device of Embodiment 1 is applied. It is a block diagram showing the outline | summary of the control structure of the steering control apparatus for vehicles of Example 1. FIG. 3 is a flowchart illustrating a steering reaction force control process according to the first embodiment. It is a schematic explanatory drawing showing the structure of the additional steering reaction force of Example 1. FIG. 3 is an additional steering reaction force amount setting map based on the vehicle speed according to the first embodiment. 3 is an additional steering reaction force gradient adjustment map based on a road surface friction coefficient according to the first embodiment. 3 is an additional steering reaction force amount adjustment map based on a turning radius of a travel path according to the first embodiment. 6 is an additional steering reaction force amount adjustment map based on the contact time according to the first embodiment. It is a characteristic view which performs contact possibility determination and contact determination based on the relationship between relative speed and contact time. It is a characteristic view showing the additional steering reaction force grant state when the contact time of Example 1 becomes less than predetermined time. It is explanatory drawing showing the additional steering reaction force characteristic based on the relative position with the obstruction of Example 1. FIG. It is an additional steering reaction force amount adjustment map based on a relative position with the obstacle of Example 1. It is an additional steering reaction force amount adjustment map based on the lateral displacement with the obstacle of Example 1. It is the schematic showing the structure of the hydraulic power steering system of Example 2. FIG. FIG. 6 is a schematic diagram illustrating a configuration of an electric power steering system according to a third embodiment. FIG. 6 is a schematic diagram illustrating a configuration of an electric power steering system according to a third embodiment. FIG. 6 is a schematic diagram illustrating a configuration of a reaction force applying unit according to a fourth embodiment. It is the schematic showing the structure of the reaction force provision means of Example 5.

  FIG. 1 is a configuration diagram of a steer-by-wire system to which the vehicle steering control device of the first embodiment is applied. The vehicle steering control device is a steering mechanism 3 (corresponding to a steering means) that steers the steering mechanism 1 and tires 2a and 2b (hereinafter referred to as steered wheels 2) according to the operation state of the steering 7. ), A clutch mechanism 50 that mechanically connects the steering mechanism 1 and the steering mechanism 3 according to the situation, and a controller 4 (electrically controlling the steering mechanism 1, the steering mechanism 3, and the clutch mechanism 50). A steering reaction force controller 4a, a steering controller 4b, and a clutch controller 4c). During the steer-by-wire control, the steering mechanism 1 and the steering mechanism 3 are electrically connected via the controller 4 while being mechanically separated. On the other hand, the system is mechanically connected by the clutch mechanism 50 during a system failure or the like.

  The steering mechanism 1 has a steering reaction force motor 5 (corresponding to a reaction force applying means) that generates a steering reaction force, and an output shaft of the steering reaction force motor 5 is connected to a handle shaft. The steering mechanism 1 also includes a steering angle sensor 8 that detects the steering angle (operation angle) of the steering 7, and a steering reaction force motor current sensor 18 that detects the load current of the steering reaction force motor 5 (the steering reaction force controller 4a). Built-in), a steering reaction force motor angle sensor 21a for detecting the motor rotation angle of the steering reaction force motor 5, and a torque sensor 22 for detecting the steering torque of the driver.

  The steered mechanism 3 includes a steered motor 9 that steers the steered wheels 2. The rotational motion of the steered motor 9 is converted into the axial motion of the rack shaft 11 via the gear mechanism 10. Further, tie rods 12a and 12b are provided on both sides of the rack shaft 11, and the steered wheels 2 are steered through knuckle arms 13a and 13b connected to the tie rods 12a and 12b. The steered motor 9 includes a steered motor angle sensor 21 b that detects the motor rotation angle of the steered motor 9.

  The steered mechanism 3 includes a steered angle sensor 15 that detects the rotation angle of the pinion shaft 14 of the rack and pinion mechanism 17. The detected turning angle corresponds to the axial displacement amount of the rack shaft 11 and also corresponds to the turning amount (steering actual angle) of the steered wheels 2. The steered mechanism 3 directly detects the steered motor current sensor 16 that detects the load current (steered actual current) of the steered motor 9 and the tire lateral force (road reaction force) input from the steered wheels 2. Possible axial force sensors 19a, 19b.

  The clutch mechanism 50 includes an upper-side engagement element 53 integral with the upper shaft 51 coupled to the steering mechanism 1, a lower-side engagement element 54 integral with the lower shaft 52 coupled to the steering mechanism 3, and an upper-side engagement element. 53 and an engagement actuator 55 that controls the engagement state between the lower side engagement element 54 and the lower side engagement element 54 by electromagnetic force. When the upper-side engagement element 53 and the lower-side engagement element 54 are engaged by the engagement actuator 55, the rack shaft 11 is moved by the operation of the steering 7 and can be steered. When the steering reaction torque motor 5 or the steering motor 9 can assist the steering torque when the clutch mechanism 50 is engaged, the electric motor that performs torque assist according to the steering torque detected by the torque sensor 22. Operates as a power steering system. Further, in order to apply a reaction force to the steering 7, an additional steering reaction force may be applied by controlling the fastening torque capacity of the clutch mechanism 50.

  The vehicle steering control device images a vehicle speed sensor 61 that detects a vehicle speed, a yaw rate sensor 62 that detects a yaw rate generated in the vehicle, a lateral acceleration sensor 63 that detects a lateral acceleration of the vehicle, and an image of a driver's line of sight. Operation information for detecting operation information of a driver camera 64, a seat surface pressure sensor 65 for detecting a surface pressure distribution of a seating surface of a driver's seat, and switches for operating each system such as a navigation system, an audio system, or an air conditioner system. And a detector 66.

  The controller 4 controls the steering reaction force controller 4 a that controls the operation state of the steering reaction force motor 5, the steering controller 4 b that controls the steering state of the steering motor 9, and the engagement state of the clutch mechanism 50. And a clutch controller 4c. Each controller is connected to the bidirectional communication line 20 and configured to be able to transmit and receive each other's control state and sensor signals. In addition, various sensors are connected to the bidirectional communication line 20, and each controller receives the control state of the other controller and the sensor signal as necessary to control each actuator.

  FIG. 2 is a block diagram illustrating an outline of a control configuration of the vehicle steering control device according to the first embodiment. The steering reaction force controller 4a calculates the steering command angle of the steered wheels 2 based on the steering angle detected by the steering angle sensor 8, the vehicle speed detected by the vehicle speed sensor 61, and the yaw rate detected by the yaw rate sensor 62. And transmitted to the steering controller 4b.

Further, the steering reaction force controller 4a includes a steering reaction force calculation unit 40a that calculates a steering reaction force according to road surface conditions and vehicle behavior based on the road surface reaction force detected by the axial force sensor 19 and various sensor signals. Have.
It also monitors the driving state (vehicle speed, yaw rate, lateral acceleration, etc.), steering state and driver state (gaze direction, posture, switch operation state, etc.), etc. It includes a situation detection unit 40b that detects a situation that has a high possibility even if it does not actually occur) (hereinafter referred to as unintentional steering).
Moreover, when the unintentional steering is detected by the situation detection unit 40b, the unintentional steering restriction unit 40c that calculates an additional steering reaction force that suppresses the change in the steering angle is provided. The unintended steering restricting unit 40c calculates an additional steering reaction force to be added to the steering reaction force calculated by the steering reaction force calculating unit 40a according to the detected situation. Details of unintentional steering will be described later.

  When the unintentional steering is detected by the situation detection unit 40b, the steering reaction force controller 4a is calculated by the unintentional steering restriction unit 40c to the normal steering reaction force calculated by the steering reaction force calculation unit 40a. The additional steering reaction force is added and output to the steering reaction force motor 5. On the other hand, when unintentional steering is not detected, the steering reaction force calculated by the steering reaction force calculator 40 a is output to the steering reaction force motor 5. The steering reaction force motor 5 is driven to control the steering reaction force based on the steering reaction force motor angle signal of the steering reaction force motor angle sensor 21a and the steering reaction force motor current of the steering reaction force motor current sensor 18.

  Further, the steering reaction force controller 4a constantly diagnoses whether or not the steer-by-wire control is executed. When the steer-by-wire control is executed, a clutch release command is issued to the clutch controller 4c. Output. On the other hand, when the steer-by-wire control is stopped or when there is a clutch engagement request based on another signal, a clutch engagement command (including variable engagement torque capacity control) is output to the clutch controller 4c.

  In the turning controller 4b, the turning motor angle signal of the turning motor angle sensor 21b and the turning motor current of the turning motor current sensor 16 are obtained so that the turning command angle calculated in the steering reaction force controller 4a can be obtained. The steering motor 9 is driven on the basis of the steering wheel 2 to control the steering wheel 2. The clutch controller 4c controls the engagement state of the engagement actuator 55 based on the clutch control signal received from the steering reaction force controller 4a. In the first embodiment, various calculations and determination processes are performed by the steering reaction force controller 4a, but may be performed by other controllers.

FIG. 3 is a flowchart illustrating the steering reaction force control process according to the first embodiment.
In step S101, driver information measured by various sensors is read into the memory. Specifically, the driver's line-of-sight direction detected by the driver camera 64 and the seat surface pressure difference detected by the seat surface pressure sensor 65 are read. Here, the seat surface pressure sensor 65 monitors, for example, the surface pressure distribution in the front, rear, left, and right, and detects the difference in surface pressure between the front, back, left, and right. At the same time, in step S110, vehicle information is read. Specifically, operation information on longitudinal acceleration, lateral acceleration, yaw rate, vehicle speed, and switches detected by various sensors is read into a memory.

  In step S102, the driver's intention, that is, unintentional steering is detected (corresponding to the situation detection unit 40b). Specifically, the probability of unintentional steering is calculated from the driver's line-of-sight direction, the seat surface pressure difference, and the current and past states. If the probability is higher than a predetermined probability, it is determined that the possibility of unintentional steering is high. To do. Hereinafter, examples of determination of unintended steering will be listed.

・ Judgment examples based on gaze direction
(i) When the driver's line-of-sight direction is in the direction of the passenger compartment continuously for a predetermined time (that is, the driver's line-of-sight direction is looking aside in the passenger compartment determined by experiments or the like) If the vehicle is in the direction of the passenger compartment for a predetermined period of time
(ii) The driver's line-of-sight direction is in the direction of the passenger compartment other than the direction of the meter, driving operation equipment (operation equipment related to driving operations such as steering and shift knobs), and mirrors related to driving operations (room mirrors and side mirrors). When there is
(iii) When the driver's line-of-sight change cycle is short and the frequency of saccades (rapid eye movements) is extremely high within a given time period (that is, when the driver's mental state seems unstable)
・ Judgment example based on surface pressure difference (driver's center of gravity position)
(iv) When the driver's seat surface pressure difference is large (for example, when the driver is leaning to try to pick something that has fallen on his / her feet etc.) When moving forward from the normal driving posture.)
(v) When the driver's seat surface pressure is large in front and back and left / right difference, for example, when the surface pressure is high only on the left rear side (the driver is twisting his body while trying to pick up the load placed in the rear seat) (I.e., when the driver's center of gravity moves in the front-rear direction and the left-right direction with respect to the normal driving posture)
・ Judgment examples based on gaze direction and surface pressure difference
(vi) When the driver ’s line-of-sight direction is outside the vehicle, but the left-right difference in the driver's seat pressure is large (for example, when the center of gravity moves while trying to pick up some luggage in the passenger seat, When the load movement is generated by operating the navigation switches while driving)
・ Judgment examples regardless of gaze direction or surface pressure difference
(vii) Immediately before the vehicle and obstacles come into contact with each other regardless of the driver's line of sight (that is, when the driver is likely to shake and perform unnecessary steering operations)
(viii) When the driver is performing an operation for adjusting the seat position (for example, when a switch for adjusting the seat position is operated)
(ix) When the driver is operating a switch of a device that is not related to the driving operation (for example, when the navigation system or audio switch is operated)

  That is, the driver's line-of-sight direction information obtained from the moving image captured by the driver camera 64, the driver's center-of-gravity position information obtained from the seat surface pressure sensor 65, operation system switch operation information, and the like correspond to any of the above. When it is determined, the past history information and the like are searched. Then, after a situation constituted by a combination of these detection signals, the probability of occurrence of unintentional steering with an unstable steering angle is calculated, and when the probability is high, there is a high possibility that unintentional steering will occur. When the probability is low, it is determined that unintentional steering does not occur. The probability may be set not only based on the past history but also based on a combination of detection signals set in advance or within the region.

  In step S103, when it is determined that unintentional steering occurs, automatic adjustment of the additional reaction force by the steering reaction force motor 5 is executed based on the vehicle information read in step S110 (unintentional). Equivalent to the steering restricting portion 40c). Additional reaction force control during unintentional steering will be described later.

In step S104, an actuator for applying an additional reaction force is automatically selected. This automatic selection is for identifying the type of actuator capable of generating a reaction force mounted on the vehicle and generating a reaction force corresponding to that type. In the first embodiment, the steering reaction force motor 5 is identified as an actuator capable of generating a reaction force. As will be described in other embodiments, it goes without saying that any steering device capable of controlling the steering reaction force, such as a hydraulic power steering system or an electric power steering system, can be mounted.
In step S105, an additional reaction force is applied to the steering 7 for a predetermined time set in advance, and after the applied steering reaction force is held for a predetermined time, the reaction force is automatically released. Note that the time (predetermined time) for which the applied steering reaction force is held is a time determined in advance by experiments or the like, and is a time that can be appropriately changed in design.

[Unintentional steering restriction processing]
Next, the unintended steering restriction process performed in step S103 will be described. In the vehicle steering control device according to the first embodiment, when the unintentional steering of the driver is detected, the additional steering reaction force is added to the normal steering reaction force to suppress the change in the steering angle. Hereinafter, how to apply the additional steering reaction force and the calculation of the amount of additional steering reaction force will be described.

(How to apply additional steering reaction force due to unintended steering regulation)
In Example 1, the structure which provides a steering reaction force with the steering reaction force motor 5 which is an electric motor is employ | adopted. FIG. 4 is a schematic explanatory diagram illustrating the configuration of the additional steering reaction force according to the first embodiment. FIG. 4A shows the case where the steering angle is 0 (neutral position), and FIG. 4B shows the case where the steering angle is θ1. As shown by the thin solid line in FIG. 4 (a), generally, during normal steering, the road reaction force increases as the steering angle increases, so the steering reaction force increases, and near the maximum value of the steering angle. In order to give a sense of abutment, a larger steering reaction force is produced. It should be noted that a hysteresis characteristic is provided for applying the steering reaction force.
Here, when a command for giving an additional steering reaction force is output when the steering angle is neutral, a command for alternately repeating the reaction force on the right side and the reaction force on the left side in a short time (for example, 5 msec) is output. (See thick solid line in FIG. 4 (a)). If the reaction force is applied to the left and right in such a short time that the frequency becomes higher than the steering frequency of the driver in this way, the steering 7 does not move, and the driver tries to steer left or right. A reaction force can be felt, and a change in the steering angle is suppressed.
Similarly, as shown in FIG. 4B, when a command for applying an additional steering reaction force is output in a state where the steering angle θ1 is maintained, a reaction force on the right side and a reaction force on the left side are output in a short time. A command for alternately repeating the force is output (see the thick solid line in FIG. 4B). Therefore, the change in the steering angle from the steering angle θ1 is suppressed as in the operation at the neutral position.

(Additional steering reaction force based on vehicle speed)
FIG. 5 is an additional steering reaction force amount setting map based on the vehicle speed of the first embodiment. As shown in FIG. 5A, when the vehicle speed is high, the maximum steerable value decreases as the vehicle speed increases. This is because if the turning angle of the steered wheel 2 is increased at a high vehicle speed and a large cornering force is generated, the lateral acceleration increases, the cornering force on the rear wheel side tends to reach its limit, and the vehicle behavior becomes unstable. Because it becomes. In other words, as the vehicle speed increases, the range of the steering angle that can achieve stable vehicle behavior and the range of the steering angle change are limited, and the change in the steering angle that changes due to the steering input torque of the driver is suppressed. Is desirable. Therefore, as shown in FIG. 4B, the amount of additional steering reaction force is set to increase as the vehicle speed increases. As a result, even if a steering torque unintended by the driver is applied to the steering wheel 7, the steering angle change inevitably becomes small at high vehicle speeds, so that steering over-rotation due to unintentional steering is suppressed and vehicle behavior is stabilized. Can be achieved.

(Unintentional steering regulation based on road surface friction coefficient)
FIG. 6 is an additional steering reaction force gradient adjustment map based on the road surface friction coefficient of the first embodiment. First, the road surface friction coefficient μ is estimated in the unintentional steering restricting section 40c (corresponding to a road surface friction coefficient detecting means). For example, the road surface friction coefficient μ is estimated based on the relationship between the turning angle and the actual yaw rate or the relationship between the wheel speed change and the actual acceleration. When the road surface friction coefficient μ is low, vehicle behavior tends to become unstable due to unintended steering. Therefore, as shown in FIG. 6A, the increase gradient ΔF of the additional steering reaction force is increased as the road surface friction coefficient μ is lower. In other words, as shown in the additional reaction force characteristic enlarged view of FIG. 6B, at the time of low μ, the rising gradient when increasing the additional steering reaction force is steeper than at the time of high μ. As a result, at low μ, the additional reaction force quickly acts on the steering wheel 7. Therefore, the steering angle change can be further suppressed, and the vehicle behavior can be stabilized.

(Unintentional steering regulation based on the turning radius of the road in the direction of travel)
FIG. 7 is an additional steering reaction force amount adjustment map based on the turning radius of the travel path of the first embodiment. First, the unintentional steering restricting section 40c calculates the turning radius R of the travel path in the vehicle traveling direction (corresponding to turning radius detecting means). The calculation of the turning radius R may be based on image analysis of the imaging camera, or may be based on information from the navigation system, information notified from the roadside by the ITS system, or the like. When the turning radius R is small, it is a sharp curve or the like, and it is considered that the driver can turn by operating the steering 7 relatively large. Therefore, at this time, the amount of additional steering reaction force is set small so as not to obstruct the steering operation. On the other hand, when the turning radius R is large, it is very close to a straight road, and it is considered that the driver hardly operates the steering wheel 7. Therefore, at this time, the amount of additional steering reaction force is increased so as to hold the steering 7 firmly. In other words, by restricting the steering angle range that the driver can operate as the turning radius R increases, unintentional steering can be restricted while avoiding the effect on normal steering.

(Unintentional steering regulation based on contact with obstacles, etc.)
(A) Relationship Between Contact Time with Obstacle and Additional Steering Reaction Force Amount FIG. 8 is an additional steering reaction force amount adjustment map based on the contact time according to the first embodiment. First, the unintentional steering restricting unit 40c detects a contact time with an obstacle positioned ahead in the vehicle traveling direction. Specifically, the presence of an obstacle ahead of the vehicle, the distance to the obstacle, the size of the obstacle in the lane width direction, and the like are measured using a laser radar, a millimeter wave radar, an imaging camera, or the like. Next, the relative vehicle speed between the host vehicle and the obstacle is measured, and the time for the host vehicle to reach the obstacle, that is, the contact time is calculated by dividing the distance to the obstacle by the relative vehicle speed.

  FIG. 9 is a characteristic diagram for performing contact possibility determination and contact determination based on the relationship between the relative speed and the contact time. When the relative speed is low and the contact time is long, the contact can be avoided by normal steering, and can be avoided by normal braking. However, the lower limit that can be avoided by normal steering regardless of the relative speed is the contact time T1. Further, the limit that can avoid contact regardless of the relative speed by emergency steering or emergency braking is the contact time T2. Considering the normal braking avoidance lower limit and the braking avoidance limit, there are areas that can be avoided even if the contact time is short depending on the relative speed, but when avoiding by steering, the determination is based on the contact times T1 and T2. It can be seen that it is preferable.

Therefore, when the contact time is longer than the predetermined time T1, which is set in advance, it is determined that a sufficient avoidance time is ensured until the contact, and the driver can avoid the contact, and the additional steering reaction force is applied. Do not do. Next, when the unintentional steering restriction unit 40c detects a situation where the contact time is less than the predetermined time T1, it is determined that there is a high possibility of contact between the obstacle and the host vehicle, and unintentional steering is performed. to decide.
In general, when a driver perceives contact with an obstacle, he / she tends to put more effort into the arm with a defense reaction than to think about the next action (contact avoidance action, etc.). It is difficult to stabilize the vehicle behavior by causing unintentional steering. Therefore, when the contact time is less than the predetermined time T1, an additional steering reaction force is applied. Further, the shorter the contact time, the larger the additional steering reaction force amount. As a result, unintentional steering does not occur even when a force is applied to the steering wheel 7 unconsciously, and generation of unnecessary vehicle behavior can be suppressed.

If the contact time is less than the predetermined time T2, it is determined that it is extremely difficult to avoid contact, and the amount of additional steering reaction force is further increased. This makes it easier for the driver to hold onto the steering wheel 7 and keep his posture during contact. In addition, even if an unintended force is applied to the steering wheel 7, the steering wheel 7 can be firmly held, so that unnecessary vehicle behavior can be further suppressed.
FIG. 10 is a characteristic diagram showing an additional steering reaction force application state when the contact time is less than the predetermined time T2. When the additional steering reaction force is applied, in the above-described example, at a certain steering angle, the additional steering reaction force applied in the right steering direction and the additional steering reaction force applied in the left steering direction have the same magnitude. In contrast, when it is determined that it is extremely difficult to avoid contact, the additional steering reaction force is applied so that the maximum steering reaction force can be obtained both in the right steering direction and in the left steering direction.

  Specifically, as shown in FIG. 10A, when the steering angle θ1 is to be steered to the right from θ1, depending on the difference between the maximum steering reaction force Frmax during right steering and the normal steering reaction force Fr. When an additional steering reaction force is applied and an attempt is made to steer leftward from θ1, an additional steering reaction force corresponding to the difference between the maximum steering reaction force Flmax during left steering and the normal steering reaction force Fl is applied. FIG. 10B is a characteristic diagram showing the relationship of the absolute value of the additional steering reaction force with respect to the steering angle. Thus, by generating the maximum steering reaction force so as to maintain a certain steering angle, the steering angle change of the steering 7 is suppressed as much as possible.

  If the amount of additional steering reaction force is not given, unintentional steering may occur due to the acceleration change accompanying the contact with the first obstacle. Secondary contact can also occur. Further, when the power steering control is executed by engaging the clutch mechanism 50, the steered wheel 2 and the steering 7 operate integrally. Therefore, unintended turning occurs on the steered wheel 2 side when the vehicle behavior changes due to contact, and this steered force may cause the steering 7 to rotate. At this time, if the driver is holding onto the steering wheel 7, there is a risk that a rotational force is applied from the steering wheel 7 to the driver. However, since unintentional steering is suppressed at the stage before contact, secondary contact can also be suppressed, and rotation of the steering wheel 7 by force from the steering wheel 2 can be suppressed.

  In addition, the unintentional steering restricting unit 40c detects when the vehicle is in contact as an unintentional steering occurrence state. Specifically, when the acceleration detected by the acceleration sensor 67 is equal to or greater than a predetermined value, it is determined that the contact is being made. In the case of a vehicle equipped with an airbag, this determination may be made at the time of contact by detecting an operation signal of the airbag. This is because the airbag monitors information on the host vehicle (contact with an obstacle based on the acceleration of the host vehicle) and determines the ignition timing (operation signal). When it is determined that the vehicle is in contact, an additional steering reaction force is applied for a predetermined time from the time of contact to hold the steering wheel 7.

(B) Relationship between Relative Position with Obstacle and Amount of Additional Steering Reaction Force FIG. 11 is an explanatory diagram showing the additional steering reaction force characteristic based on the relative position with the obstacle in the first embodiment, and FIG. 12 shows the obstacle in the first embodiment. It is an additional steering reaction force amount adjustment map based on a relative position with an object. As shown to Fig.11 (a), a progress prediction locus | trajectory is set based on the steering angle etc. of the steering wheel of the own vehicle. At the steering angle 0, that is, at the neutral position, the travel prediction trajectory is a straight line, and when the steering angle θ is a predetermined value, it turns and becomes a curved line. In this progress prediction trajectory, it is determined whether an obstacle ahead is present on the right side or on the left side.
For example, as shown in FIG. 11A, when the host vehicle is turning to the right, it is assumed that there is an obstacle (preceding vehicle) on the right side of the predicted travel trajectory. If there is a high possibility that the vehicle will come into contact with an obstacle over the course of the contact time, if the driver is unable to steer properly and the steering wheel 7 is steered further to the right, the possibility of contact with the obstacle is Further increase. Further, when the driver is holding the steering wheel 7 immediately before contact, there is a possibility that the driver may steer further to the right side by unintentional steering, and the possibility of contact with an obstacle is also increased.

Thus, as shown in FIG. 11B, when there is an obstacle on the right side of the progress prediction trajectory, the steering angle change to the right side is suppressed. Specifically, the additional steering reaction force is applied so as to be the maximum steering reaction force during right steering, and a small additional steering reaction force is applied so as to allow a change in the steering angle to the left. The dotted line in FIG. 12 represents the absolute value of the additional steering reaction force when an obstacle is present on the right side of the progress prediction trajectory during right steering, and the solid line in FIG. 12 is an obstacle on the left side of the progress prediction trajectory during left steering. Represents the absolute value of the additional steering reaction force. Also, the alternate long and short dash line in FIG. 12 indicates the absolute value of the additional steering reaction force with respect to the side where the obstacle is not present in the progress prediction locus.
As a result, even if the driver is caught by the steering wheel 7 immediately before contact or the like, the posture is not disturbed toward the side where the obstacle exists, and on the other hand, the side where the obstacle does not exist can be quickly avoided. Thus, unintended steering can be suppressed.

(C) Relationship Between Lateral Displacement with Obstacle and Additional Steering Reaction Force Amount FIG. 13 is an additional steering reaction force amount adjustment map based on the lateral displacement with an obstacle according to the first embodiment. First, as shown in FIG. 13A, the unintentional steering restricting unit 40c estimates a vehicle width direction distance δ between the predicted travel path of the host vehicle and the obstacle. And as shown in FIG.13 (b), the gain K according to the vehicle width direction distance (delta) is set. This gain K acts on the additional steering reaction force applied to the side where there is no obstacle. Since the possibility of contact is high when the distance δ is small, it is added to prepare for the acceleration change at the time of contact. Increase steering reaction force. On the other hand, when the distance δ is large, the possibility of contact is low and the change in acceleration at the time of contact is predicted to be small, so the additional steering reaction force is reduced.

  In other words, a larger steering reaction force is applied as the distance in the vehicle width direction between the predicted travel path of the host vehicle and the obstacle becomes smaller. Note that the gain K is set to 0 when the distance δ does not come into contact with an obstacle even if the vehicle width and safety factor of the host vehicle are taken into consideration. Thereby, when the possibility of contact is low, an unnecessary reaction force is not added, so that the driver does not feel uncomfortable. When applied to the above (b), the additional steering reaction force applied to the side where the obstacle is present is set to the maximum steering reaction force. When the reaction force amount is set, the additional steering reaction force amount may be variably controlled by applying the gain K.

(Unintentional steering regulation based on body vibration)
Next, unintended steering regulation based on vehicle body vibration will be described. First, the unintentional steering restriction unit 40c detects vertical acceleration, longitudinal acceleration, and lateral acceleration generated in the vehicle body based on the acceleration sensor 67 and the like. These acceleration changes represent vehicle body pitching vibration, bounce vibration, roll vibration, and the like. If the magnitude of these vibrations exceeds a predetermined level, acceleration may act on the driver's body and cause unintentional steering, and unintentional steering may occur due to resonance of the steering system. There is a fear. Therefore, when the change in acceleration is greater than or equal to a predetermined value, an additional steering reaction force is applied so as to hold the steering 7 firmly. Thereby, unintended steering is restricted.

As described above, the effects listed below can be obtained in the first embodiment.
(1) A steering wheel 7 steered by the driver, a steering mechanism 3 (steering means) for steering the steered wheels 2 according to the steering state of the steering wheel 7, and a steering reaction force to the steering wheel 7 A steering reaction force motor 5 (reaction force applying means) and a situation detection unit 40b (situation detection means) for detecting a situation in which a steering operation unintended by the driver occurs are provided. When the situation where a steering operation unintended by the driver occurs is detected by the unit 40b, a steering reaction force is applied so as to suppress a change in the steering angle. Therefore, by suppressing unintentional steering, it is possible to suppress changes in vehicle behavior that are not intended by the driver, and to prevent the driver from feeling uncomfortable.

  (2) The situation detection unit 40b detects a posture in which the driver leans forward or a posture in which the body is twisted. Specifically, by detecting the driver's situation based on the driver's line-of-sight direction, seat surface pressure difference, etc., it is possible to quickly detect whether or not unintended steering is likely to occur, and to suppress changes in steering angle Can be implemented immediately.

  (3) The situation detection unit 40b calculates the probability of occurrence of an unintended steering operation, and detects a situation where the probability is equal to or higher than a predetermined probability. Specifically, the probability of occurrence of unintentional steering is calculated from past history information recorded in the situation detection unit 40b, and it is determined that the combination is a combination of various sensor signals whose probability is equal to or greater than a predetermined probability. In addition to the history information, when the display or operation system switch is operated at the present time, and the situation where the steering state is unstable due to these operations is detected, the probability is more than a predetermined probability. Judge. Therefore, the occurrence of unintended steering can be stably detected in advance based on various information of the driver.

  (4) A steering reaction force is applied by a steering reaction force motor 5 (load application mechanism) disposed on the steering column. Therefore, the additional steering reaction force can be applied with high responsiveness using the existing structure of steer-by-wire control without providing a new mechanism.

  (5) A vehicle speed sensor 61 (vehicle speed detection means) for detecting the vehicle speed is provided, and a larger steering reaction force is applied as the detected vehicle speed is higher. That is, even if a steering torque unintended by the driver is applied to the steering wheel 7, the change in the steering angle is inevitably small at high vehicle speeds. Therefore, the steering over-rotation due to unintentional steering is suppressed, and the vehicle behavior is stabilized. Can be planned.

  (6) An unintended steering restricting section 40c (road surface friction coefficient detecting means) for detecting the road surface friction coefficient μ is provided, and a steering reaction force having a larger increasing gradient is applied as the detected road surface friction coefficient μ is lower. As a result, at low μ, an additional reaction force is quickly applied to the steering wheel 7, so that a change in the steering angle can be further suppressed, and the vehicle behavior can be stabilized.

  (7) An unintentional steering restricting section 40c (turning radius detecting means) that detects the turning radius R of the traveling road surface is provided, and the steering angle range that can be operated by the driver is limited as the detected turning radius R increases. A steering reaction force is applied. Therefore, unintentional steering can be regulated while avoiding the influence on normal steering.

  (8) The situation detection unit 40b detects a situation where the contact time until contact with the obstacle is less than the predetermined time T1. Therefore, when the contact can be sufficiently avoided, an uncomfortable feeling given to the driver can be suppressed by not applying an unnecessary steering reaction force.

  (9) A larger steering reaction force is applied as the time until contact with an obstacle is shorter. As a result, unintentional steering does not occur even when a force is applied to the steering wheel 7 unconsciously, and generation of unnecessary vehicle behavior can be suppressed. Further, since it is easy for the driver to hold the steering wheel 7 and maintain his / her posture at the time of contact, his / her posture can be quickly reestablished after the contact and the vehicle can be returned to driving at an early stage. Further, even if an unintended force is applied to the steering wheel 7, the steering wheel 7 can be kept in a state of hardly moving, so that the occurrence of unnecessary vehicle behavior can be further suppressed.

  (10) A larger steering reaction force is applied as the distance in the vehicle width direction between the predicted travel path of the host vehicle and the obstacle becomes smaller. Thereby, when the vehicle width direction distance is small, since the possibility of contact is high, it is possible to prepare for acceleration change at the time of contact. On the other hand, when the vehicle width direction distance is large, the possibility of contact is low. In this case, since an unnecessary reaction force is not added, the driver does not feel uncomfortable.

  (11) The situation detection unit 40b detects when the vehicle is in contact. Therefore, it is possible to avoid unnecessary steering force being transmitted to the driver via the steering wheel 7 due to unintended steering by the driver accompanying the contact and the force transmitted from the steered wheel side accompanying the contact.

  (12) An acceleration sensor 67 (acceleration detection means) for detecting the acceleration of the vehicle body is provided, and the situation detection unit 40b determines that the contact is being made when the detected acceleration is equal to or greater than a predetermined value. Therefore, it is possible to avoid unnecessary steering force from being transmitted to the driver via the steering wheel 7 due to unintentional steering by the driver accompanying the change in acceleration and the force transmitted from the steered wheel side.

  (13) The situation detection unit 40b determines that the airbag operation signal is output as a contact. Therefore, the additional steering reaction force can be immediately applied according to the operation signal of the airbag.

  (14) The situation detection unit 40b detects a situation in which the change in acceleration due to vehicle body vibration is greater than or equal to a predetermined value. That is, when the change in acceleration is greater than or equal to a predetermined value, unintentional steering due to acceleration acting on the driver's body or unintentional steering due to resonance of the steering system may occur. By applying the additional steering reaction force so as to hold 7 firmly, unintentional steering can be regulated.

  (15) After the steering reaction force is applied, the applied steering reaction force is held for a predetermined time. In other words, after the additional steering reaction force is applied for a predetermined time, the applied additional steering reaction force is released. Therefore, it is possible to avoid unnecessary steering force being transmitted to the driver via the steering wheel 7 due to unintended steering by the driver accompanying the contact and the force transmitted from the steered wheel side accompanying the contact.

  Next, Example 2 will be described. FIG. 14 is a schematic diagram illustrating the configuration of the hydraulic power steering system according to the second embodiment. A rotary valve mechanism 71 is connected to the steering shaft 7 a to which the steering 7 is connected, and the rotary valve mechanism 71 is connected to a power cylinder 74 via pipe lines 72 and 73. When the hydraulic pressure discharged from the oil pump 70 is supplied, the oil path is switched by the rotary valve mechanism 71 according to the steering torque, and the hydraulic pressure is supplied into the power cylinder to assist the movement of the rack shaft 11. At this time, the conduits 72 and 73 are provided with electromagnetic valves 72a and 73a whose orifice diameter can be changed by electromagnetic force. In the controller 400, a situation detection unit 40b and an unintentional steering restriction unit 40c similar to those in the first embodiment are provided. In the first embodiment, the normal steering reaction force is also processed by calculation. However, in the second embodiment, the normal steering reaction force is transmitted through the mechanical configuration, and is not particularly calculated. Only the additional steering reaction force is calculated. . The controller 400 includes the same sensors as in the first embodiment.

When the possibility of unintentional steering is detected by the situation detection unit 40b, an unintentional steering restriction unit 40c outputs a command for applying an additional steering reaction force. Accordingly, the orifice diameters of the electromagnetic valves 72a and 73a are controlled to be small, the oil in the power cylinder becomes difficult to flow, and the movement of the rack shaft 11 is restricted, thereby suppressing the change in the steering angle of the steering wheel 7. To do.
(16-1) The reaction force imparting means imparts the steering reaction force by the power cylinder 74 (addition imparting mechanism) arranged in parallel with the rack shaft 11 (tire axis). Thereby, the same effect as Example 1 is acquired. Further, unintentional steering can be suppressed only by adding an electromagnetic valve to a vehicle having a general hydraulic power steering system.

  Next, Example 3 will be described. 15 and 16 are schematic views showing the configuration of the electric power steering system. An electric power steering mechanism 80 is attached to the steering column 7 a connected to the steering 7. In the controller 401, a situation detection unit 40b and an unintentional steering restriction unit 40c similar to those in the first embodiment are provided. Further, an assist force calculation unit that outputs a steering assist command to the electric power steering mechanism 80 based on the torque detected by the torque sensor is provided. Further, as the reaction force applying means, a friction brake 81 for restricting the rotation of the steering column 7a is provided in the example shown in FIG. 15, while the axial movement of the rack shaft 11 (tire axis) is restricted in the example shown in FIG. A friction brake 82 is provided.

  When the possibility of unintentional steering is detected by the situation detection unit 40b, an unintentional steering restriction unit 40c outputs a command for applying an additional steering reaction force. As a result, the friction brake 81 or the friction brake 82 is operated to restrict the rotation of the steering shaft 7a or the axial movement of the rack shaft 11. Thereby, it becomes possible to suppress the change of the steering angle of the steering wheel 7, and the same effect as the first embodiment can be obtained.

(16-2) The reaction force applying means applies the steering reaction force by the friction brakes 81 and 82 (addition applying mechanism) arranged in parallel with the steering column 7a or the rack shaft 11 (tire shaft). Therefore, unintentional steering can be suppressed only by adding a simple configuration to a vehicle having a general electric power steering system.
Note that the reaction force applying means may be realized by an electric motor provided in the electric power steering mechanism 80 without providing the friction brakes 81 and 82. For example, unintentional steering can be regulated by causing the electric motor to output a torque obtained by subtracting the additional steering reaction force from the assist force calculated by the assist force calculation unit. In this case, since the existing electric power steering mechanism can be used as it is as the load applying mechanism, it can be realized at low cost.

  Next, Example 4 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 17 is a schematic diagram illustrating a configuration of a reaction force applying unit according to the fourth embodiment. In the first embodiment, an example in which the steering reaction force motor 5 is used to restrict the change in the steering angle of the steering 7 has been described. On the other hand, in the fourth embodiment, as shown in FIG. 17, the rear side of the steering wheel 7, that is, the drive side friction plate 91 provided at a position facing the instrument panel 100 (vehicle body) and the instrument panel 100 side. The driven side friction plate 92 is provided at a position facing the drive side friction plate 91, and the reaction force is applied by the frictional contact of these friction plates.

  A spline is formed at the end 7b1 of the upper side steering shaft 7b, and a connecting portion 7c1 that can be splined with the end 7b1 is formed at the lower side steering shaft 7c. The axial length of the end portion 7b1 is set shorter than the axial length of the hollow portion in the connecting portion 7c1. A stroke actuator 90 that can stroke the upper side steering shaft 7b in the axial direction is attached to the upper side steering shaft 7b. During normal steering, the end 7b1 and the connecting portion 7c1 are connected so that the drive-side friction plate 91 and the driven-side friction plate 92 are spaced apart in the axial direction.

  When the possibility of unintentional steering is detected by the situation detection unit 40b, an unintentional steering restriction unit 40c outputs a command for applying an additional steering reaction force. As a result, the stroke actuator 90 is actuated, and the operation of pulling the upper side steering shaft 7b into the instrument panel 100 is performed. As a result, the drive-side friction plate 91 and the driven-side friction plate 92 are brought into frictional contact, and the change in the steering angle of the steering 7 is suppressed.

  (17) The reaction force applying means applies the steering reaction force by increasing the frictional force between the steering 7 and the vehicle body. Therefore, a change in the steering angle of the steering 7 can be effectively suppressed. Note that the magnitude of the additional steering reaction force can be appropriately controlled by controlling the pulling force of the stroke actuator 90. Thereby, the same effect as Example 1 is acquired. In the fourth embodiment, the frictional force is generated by the operation of the stroke actuator 90. However, when the possibility of contact increases, the driver may manually push the steering 7 to generate the frictional force. Good. That is, when the possibility of contact is high, the driver often applies a force to the steering wheel 7 in the direction in which the steering wheel 7 is pushed. The frictional force may be generated.

  Next, Example 5 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 18 is a schematic diagram illustrating a configuration of a reaction force applying unit according to the fifth embodiment. In the first embodiment, an example in which the steering reaction force motor 5 is used to restrict the change in the steering angle of the steering 7 has been described. On the other hand, in Example 5, as shown in FIG. 18, a reaction force is applied by a mechanical engagement portion installed in the steering column. The steering shaft 7a has an engaging gear portion 7a1 having an uneven surface. Further, an engagement actuator 95 fixed to the vehicle body side and an engagement lever 96 that is operated by the engagement actuator 95 are provided. During normal steering, the engaging gear portion 7a1 and the engaging lever 96 are in a disengaged state.

  When the possibility of unintentional steering is detected by the situation detection unit 40b, an unintentional steering restriction unit 40c outputs a command for applying an additional steering reaction force. As a result, the engagement actuator 90 is operated, and the engagement lever 96 is engaged with the engagement gear portion 7a1. Thereby, the steering shaft 7a is fixed to the vehicle body side, and a change in the steering angle of the steering 7 is suppressed. Thereby, the same effect as Example 1 is acquired. In the case of the fifth embodiment, the magnitude of the additional steering reaction force is not variable.

  (18) The reaction force applying means applies a steering reaction force by engagement between the engagement lever 96 and the engagement gear portion 7a1 (mechanical engagement portion) that are normally released. Therefore, the steering reaction force can be applied by operating the engagement actuator 90 only during the engagement operation, and the power consumption can be suppressed.

  As mentioned above, although this invention was demonstrated based on Examples 1-5, if it is the structure which suppresses the change of a steering steering angle, even if it is another structure, when an unintentional steering is detected, it is contained in this invention. . For example, in the embodiment, the time for applying the additional steering reaction force is set to a predetermined time, but the predetermined time may be changed according to the driver's intention. Further, in the embodiment, the steering angle at the present time is suppressed so as not to be changed by unintentional steering, but the steering angle for applying the additional steering reaction force, the vehicle speed region, and the like may be set by the driver. For example, the driver may set a steering angle region where an additional steering reaction force is applied by a dial operation.

1 Steering mechanism 2 Steering wheel 3 Steering mechanism (steering means)
4a Steering reaction force controller 4b Steering controller 4c Clutch controller 5 Steering reaction force motor (reaction force applying means)
7 Steering 9 Steering motor (steering means)
40a Steering reaction force calculation unit 40b Situation detection unit (situation detection means)
40c Unintentional steering restriction unit 50 Clutch mechanism 61 Vehicle speed sensor 62 Yaw rate sensor 63 Lateral acceleration sensor 64 Driver camera 65 Seat pressure sensor 66 Operation information detector 67 Acceleration sensor

Claims (18)

A steering wheel steered by the driver;
Steering means for steering the steered wheels according to the steering state of the steering;
Reaction force applying means for applying a steering reaction force to the steering;
Situation detection means for detecting a situation in which a steering operation unintended by the driver occurs;
With
The reaction force applying means applies a steering reaction force so as to suppress a change in a steering angle when a situation in which a steering operation unintended by a driver occurs is detected by the situation detecting means. Vehicle steering control device. The vehicle steering control device according to claim 1,
The vehicle steering control device, wherein the situation detecting means detects a posture in which the driver leans forward or twists the body. The vehicle steering control device according to claim 1,
The situation detection means is such that the driver's line-of-sight direction is continuously in the direction of the passenger compartment for a predetermined time or more, and the driver's line-of-sight direction is a vehicle other than the direction of the driving operation device and the mirror related to the driving operation. Vehicle steering control characterized by detecting at least one of being in a room direction and having a short period of change in the driver's line-of-sight direction and a very high frequency of saccades within a predetermined time apparatus. The vehicle steering control device according to any one of claims 1 to 3,
The vehicle state control means calculates a probability that an unintended steering operation will occur, and detects a situation where the probability is a predetermined probability or more. The vehicle steering control device according to any one of claims 1 to 4,
The vehicle steering control device, wherein the reaction force applying means applies a steering reaction force by a load applying mechanism arranged in parallel with a steering column or a tire shaft. The vehicle steering control device according to any one of claims 1 to 4,
The vehicle steering control device, wherein the reaction force applying means applies a steering reaction force by increasing a frictional force between the steering and a vehicle body. The vehicle steering control device according to any one of claims 1 to 4,
The vehicle steering control device, wherein the reaction force applying means applies a steering reaction force by engagement of a mechanical engagement portion that is normally released. The vehicle steering control device according to any one of claims 1 to 7,
Vehicle speed detecting means for detecting the vehicle speed is provided;
The vehicle steering control device, wherein the reaction force applying means applies a larger steering reaction force as the detected vehicle speed is higher. The vehicle steering control device according to any one of claims 1 to 8,
A road surface friction coefficient detecting means for detecting a road surface friction coefficient is provided,
The vehicle steering control device, wherein the reaction force applying means applies a steering reaction force having a larger increasing gradient as the detected road friction coefficient is lower. The vehicle steering control device according to any one of claims 1 to 9,
Provide turning radius detection means for detecting the turning radius of the road surface,
The vehicle steering control device, wherein the reaction force applying means applies a steering reaction force so as to limit a steering angle range that can be operated by the driver as the detected turning radius increases. The vehicle steering control device according to any one of claims 1 to 10,
The vehicle steering control device, wherein the situation detection means detects a situation where a contact time until contact with an obstacle is less than a predetermined time. The vehicle steering control device according to claim 11,
The vehicle steering control device, wherein the reaction force applying means applies a larger steering reaction force as the time until contact with the obstacle is shorter. The vehicle steering control device according to any one of claims 1 to 12,
The vehicle steering control device characterized in that the reaction force applying means applies a larger steering reaction force as the distance in the vehicle width direction between the predicted travel path of the host vehicle and the obstacle becomes smaller. The vehicle steering control device according to any one of claims 1 to 13,
The vehicle steering control device, wherein the situation detection means detects when the vehicle is in contact. The vehicle steering control device according to claim 14,
An acceleration detection means for detecting the acceleration of the vehicle body is provided,
The vehicle steering control device according to claim 1, wherein the situation detecting means determines that the vehicle is in contact when the detected acceleration is equal to or greater than a predetermined value. The vehicle steering control device according to claim 14,
The vehicle steering control device, wherein the situation detecting means determines that the airbag operation signal is output as a contact. The vehicle steering control device according to any one of claims 1 to 16,
The vehicle steering control device, wherein the situation detection means detects a situation where a change in acceleration due to body vibration is a predetermined value or more. The vehicle steering control device according to any one of claims 14 to 17,
The vehicle steering control device, wherein the reaction force applying means holds the applied steering reaction force for a predetermined time after applying the steering reaction force.

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