JP6012832B1 - Vehicle steering system - Google Patents

Abstract

It is possible to effectively alert a driver of a lane departure. When the steering torque of a driver is detected and a lane departure is determined, if the steering torque is large, the vibration torque for the lane departure warning is increased, and if the steering torque is small, the lane departure warning is detected. By reducing the vibration torque for the driver and superimposing the vibration torque on the assist torque for assisting the driver's steering torque, the driver can effectively lane departure regardless of the driver's steering state. Can be notified. [Selection] Figure 2

Description

  The present invention relates to a vehicle steering device, and more particularly to a vehicle steering device for notifying a driver of a lane departure state when the vehicle departs from a lane.

  In recent years, vehicles equipped with a camera for monitoring the front have been developed. In such a vehicle, it is possible to recognize a traveling lane using a camera and determine whether or not the host vehicle deviates from the traveling lane. Further, when the host vehicle deviates from the traveling lane, it is possible to notify the driver of the lane departure.

  As a method of notifying the driver of a lane departure, generally, a method of visually, audibly, or tactilely informing is conceivable. However, visual notification is not effective in a state where the driver loses attention, for example, a doze state. In addition, there is a problem that auditory notification may give a passenger discomfort. On the other hand, the contact notification is suitable as a means for notifying the driver of the lane departure state because an effect of awakening the driver can be expected.

  Against such a background, for example, Patent Document 1 describes a method of vibrating the steering wheel when departing from the lane. In Patent Document 1, a vibration motor is incorporated in the steering wheel, and the vibration motor is energized when the vehicle departs from the lane to vibrate the steering wheel to notify the driver of the lane departure.

  As simpler methods, there are methods described in Patent Document 2 and Patent Document 3, for example. In Patent Document 2 and Patent Document 3, vibration is generated using an existing motor mounted in advance in a vehicle, and the driver is informed of the abnormality.

  In Patent Document 2, the rear wheel of the vehicle is a steering wheel. Therefore, an electric motor is provided as an actuator for steering the rear wheels. When the vehicle is likely to deviate from the road, the rear wheels are vibrated by the electric motor. Thereby, since the vehicle vibrates, the driver can recognize the lane departure as the experience information.

  In Patent Document 3, the vehicle includes an electric power steering device. In Patent Document 3, there is no description regarding lane departure. In Patent Document 3, when a danger due to the approach of an obstacle is predicted, the steering wheel is vibrated to give a warning to the driver.

Special Table 2000-530220 JP-A-10-167099 JP-A-8-175413

  In Patent Document 1, a vibration motor is incorporated in the handle. However, when a vibration motor is incorporated in the handle, there is a problem that the handle becomes large. Further, when the driver himself replaces the steering wheel with a different type, the vibration motor is lost, and therefore, there is a problem that a lane departure warning cannot be notified to the driver.

  Moreover, in patent document 2, the deviation of a lane is alert | reported to a driver | operator by vibrating the rear wheel of a vehicle. However, the vehicle vibrates depending on the road surface condition. Further, how the vibration is transmitted from the road surface to the vehicle changes according to the vehicle speed. Therefore, depending on the traveling state of the vehicle, it is assumed that the warning vibration is relatively small with respect to the vibration from the road surface state. In that case, the driver may not be aware of the vibration of the vehicle. Therefore, the method of Patent Document 2 may not be able to effectively notify the driver.

  In Patent Document 3, when the approach of an obstacle can be predicted, the handle is vibrated using the assist motor of the electric power steering apparatus. However, depending on the steering state of the driver, the assist torque for assisting the steering torque by the driver may increase. When the assist torque is large, the vibration torque for the lane departure warning with respect to the assist torque is relatively small. Therefore, there is a possibility that the driver does not notice the vibration of the steering wheel and cannot effectively notify the driver.

  Patent Document 3 describes that the amount of vibration when not steering is made larger than the amount of vibration during steering. That is, Patent Document 3 describes changing the amount of vibration depending on whether or not steering is in progress. However, there is no description about changing the vibration amount according to the steering state of the driver. As described above, the assist torque may increase depending on the steering state of the driver. When the assist torque is large, the vibration torque becomes relatively small, and the driver is not effectively notified. There is a problem that there is a possibility.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a vehicle steering apparatus capable of effectively warning a driver of a lane departure.

  The present invention is a vehicle steering apparatus mounted on a vehicle, and the vehicle includes a steering state detection unit that detects a steering state of a driver and a traveling state detection unit that detects a traveling state of the vehicle. The vehicle steering apparatus is configured to provide a target for the assist motor based on an assist motor that generates an assist torque for assisting the driver's steering and the steering state detected by the steering state detection unit. A motor drive control unit that calculates assist torque and drives the assist motor; a lane departure determination unit that determines whether the vehicle is in a lane departure state based on the traveling state detected by the traveling state detection unit; Vibration torque for calculating vibration torque to be superimposed on the assist torque when the lane departure determination unit determines that the vehicle is in a lane departure state A calculation unit, and when the vibration torque calculation unit calculates the vibration torque, the motor drive control unit uses the value obtained by adding the target assist torque and the vibration torque as the target assist torque. The motor is driven, and the vibration torque calculation unit is a vehicle steering device that changes the magnitude of the vibration torque according to the steering state detected by the steering state detection unit.

  According to the vehicle operating device of the present invention, the magnitude of the lane departure warning vibration torque to be superimposed on the assist torque of the assist motor that assists the driver's steering torque can be varied according to the steering torque. By doing so, it is possible to effectively warn the driver of a lane departure.

It is a figure which shows the structure of the steering apparatus for vehicles which concerns on Embodiment 1 of this invention. It is a block diagram which shows the internal structure of the steering apparatus for vehicles which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the steering apparatus for vehicles which concerns on Embodiment 1 of this invention.

Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a vehicle steering apparatus according to Embodiment 1 of the present invention. The vehicle steering apparatus shown in FIG. 1 is one of the preferred embodiments according to the present invention.

  The vehicle steering apparatus 1 according to the present embodiment is mounted on a vehicle such as an automobile. As shown in FIG. 1, the vehicle steering apparatus 1 includes a steering wheel 2, a steering shaft 3, a pinion gear 4, a steering angle detection unit 5, a torque sensor 6, an assist motor 7, a motor gear 8, a rack shaft 9, a tire 10, an electric motor. A power steering control device 15 and a lane departure determination unit 16 are included. The tire 10 is a front wheel of the vehicle and a steering wheel. Of course, the vehicle is also provided with a rear wheel, but in FIG. 1, the rear wheel is not shown because it is not related to the present invention.

A traveling vehicle speed detector 11, a camera unit 12, a yaw rate detector 13, and a lateral acceleration detector 14 are connected to the vehicle steering device 1. All of these devices are mounted on the vehicle.
A traveling vehicle speed detection unit 11 is connected to the electric power steering control device 15 of the vehicle steering device 1.
A traveling vehicle speed detection unit 11, a camera unit 12, a yaw rate detection unit 13, and a lateral acceleration detection unit 14 are connected to the lane departure determination unit 16 of the vehicle steering apparatus 1.

The traveling vehicle speed detection unit 11 detects the vehicle speed of the vehicle and outputs a vehicle speed signal Vs.
The camera unit 12 images the front of the vehicle and outputs a video signal Ms.
The yaw rate detector 13 detects the yaw rate of the vehicle and outputs a yaw rate signal γs. Here, the yaw rate is the rate of change of the rotation angle in the turning direction of the vehicle.
The lateral acceleration detection unit 14 detects lateral acceleration of the vehicle and outputs a lateral acceleration signal Gs.

A handle 2 that is steered by a driver is connected to one end of a steering shaft 3. A pinion gear 4 is connected to the other end of the steering shaft 3.
A steering angle detector 5 is attached to the handle 2. The steering angle detector 5 detects the steering angle of the handle 2 and outputs a steering angle signal θs.
A torque sensor 6 is attached to the steering shaft 3. The torque sensor 6 detects a steering torque Td by the driver's steering and outputs a steering torque signal Ts. The torque sensor 6 constitutes a steering torque detector.
An electric assist motor 7 is attached to the steering shaft 3 via a motor gear 8. The assist motor 7 generates a motor torque Tm for assisting the driver's steering torque Td.
The assist motor 7 is provided with a motor voltage detector (not shown) that detects the motor voltage of the assist motor 7 and outputs a motor voltage detection signal Es.
Further, the assist motor 7 is provided with a motor current detector (not shown) that detects the motor current of the assist motor 7 and outputs a motor current detection signal Is. Hereinafter, this motor current is referred to as an assist current.

The other end of the steering shaft 3 is connected to the center of the pinion gear 4. A rack shaft 9 is attached to the pinion gear 4 in a state where the rack shaft 9 is penetrated. Both ends of the rack shaft 9 are connected to the tire 10. Thus, the tire 10 is connected to the pinion gear 4 via the rack shaft 9.
The pinion gear 4 converts the rotational motion of the steering shaft 3 into linear motion of the rack shaft 9. More specifically, first, the steering shaft 3 rotates based on a combined torque (= Td + Tm) obtained by adding the steering torque Td and the motor torque Tm by the driver. The pinion gear 4 converts the rotational motion of the steering shaft 3 into linear motion of the rack shaft 9 in a direction corresponding to the rotational direction.

A steering torque signal Ts, a vehicle speed signal Vs, a motor current detection signal Is, and a motor voltage detection signal Es are input to the electric power steering control device 15. The electric power steering control device 15 further receives a lane departure determination flag from the lane departure determination unit 16. Based on these inputs, the electric power steering control device 15 calculates a target current value for driving the assist motor 7 and outputs an applied voltage E generated from the target current value to the assist motor 7. The assist motor 7 generates a motor torque Tm corresponding to the applied voltage E.
Here, in the above description, it has been described that the steering torque signal Ts, the vehicle speed signal Vs, the motor current detection signal Is, and the motor voltage detection signal Es are input to the electric power steering control device 15. It is not always necessary to input all these inputs.

A steering angle signal θs, a vehicle speed signal Vs, a video signal Ms, a yaw rate signal γs, and a lateral acceleration signal Gs are input to the lane departure determination unit 16.
The lane departure determination unit 16 determines whether or not the vehicle departs from the lane based on the above inputs, generates a lane departure determination flag, and outputs the lane departure determination flag to the electric power steering control device 15.
The lane departure state flag is, for example, 0 when the vehicle is not in a lane departure state or is not likely to depart, and is 1 when the vehicle is in a lane departure state or is likely to deviate.
For the sake of simplicity, in the following, “when the vehicle is not in a lane departure state or is not likely to deviate” is collectively referred to as “not in a lane departure state”, and “the possibility of departure from a lane” "When there is" is collectively referred to as "lane departure state".
The method for determining whether the vehicle is in a lane departure state is, for example, as follows.
First, an offset amount of the vehicle from the center line of the road is obtained from the steering angle signal θs, the video signal Ms, and the yaw rate signal γs. Next, it is determined whether or not the offset amount is larger than a preset threshold value. When the offset amount is larger than the threshold value, it is determined that the vehicle is in a lane departure state.
Further, since the current traveling direction and traveling speed of the vehicle can be calculated from the vehicle speed signal Vs and the lateral acceleration signal Gs, whether the vehicle is moving in a direction deviating from the lane or recovering from the lane deviation is calculated from these values. It is possible to determine whether the vehicle is moving in the direction of Therefore, when the offset amount is larger than the threshold value and the traveling direction of the vehicle is a lane departure direction, it may be determined that the vehicle is in a lane departure state.
Note that these methods are merely examples, and the present invention is not limited to these methods. In the present invention, any method may be used as long as it can be determined whether or not the vehicle is in a lane departure state. Therefore, the present invention is not limited to the above method, and any of the existing conventional determination methods currently proposed may be used. I will do it.

  Here, in the above description, it has been described that the steering angle signal θs, the vehicle speed signal Vs, the video signal Ms, the yaw rate signal γs, and the lateral acceleration signal Gs are input to the lane departure determination unit 16. However, it is not always necessary to input all of these inputs, and at least one of these inputs may be input.

  The lane departure determination unit 16 can also perform lane departure determination using only information from the camera unit 12. In that case, there is an effect that it can be realized by a simpler system. In that case, the lane departure determination unit 16 obtains the video signal Ms from the camera unit 12, performs image processing on the video signal Ms, and determines a lane on the road such as a white line or a yellow overtaking lane at the center of the road or on the road side. recognize. Next, the traveling lane of the host vehicle is recognized based on those lanes. Then, the distance between the traveling lane and the right end of the host vehicle or the distance between the traveling lane and the left end of the host vehicle is obtained, and the shorter one of the distances is equal to or less than a preset threshold value. In this case, it is determined that the vehicle is in a lane departure state. Alternatively, when the distance between the center line of the traveling lane and the center position of the head of the host vehicle is equal to or greater than a preset threshold value, the departure state may be determined. Further, by analyzing the video signal Ms, for example, it is possible to determine whether the vehicle is traveling and the lane is the opposite lane based on the characteristics of characters written on the road of the lane. It is determined that the vehicle is in a lane departure state.

  In the present embodiment, an example in which the lane departure determination unit 16 is provided separately from the electric power steering control device 15 and the camera unit 12 has been described for the sake of easy understanding. However, the present invention is not limited to this, and the electric power steering control device 15 or the camera unit 12 may have the function of the lane departure determination unit 16.

  Next, a specific operation of the vehicle steering apparatus according to the first embodiment will be described with reference to a system block diagram of the vehicle control apparatus shown in FIG.

As shown in FIG. 2, in the present embodiment, in the electric power steering control device 15, a vibration torque calculation unit 17, an assist torque calculation unit 18 based on the steering torque, an adder 19, and a current control unit 20. And are provided.
The assist torque calculator 18 based on the steering torque, the adder 19 and the current controller 20 calculate a target assist torque for the assist motor 7 based on the steering state detected by the steering state detector, A motor drive control unit for driving the assist motor 7 is configured.

  As described above, the lane departure determination unit 16 is connected to the steering angle detection unit 5, the lateral acceleration detection unit 14, the yaw rate detection unit 13, the camera unit 12, and the traveling vehicle speed detection unit 11. Each of these parts constitutes a traveling state detection unit that detects the traveling state of the vehicle, but it is not always necessary to provide all of these parts, and at least one of these parts is provided as necessary. You can do it. A steering angle signal θs, a lateral acceleration signal Gs, a yaw rate signal γs, a video signal Ms, and a vehicle speed signal Vs are input to the lane departure determination unit 16 from these units. The lane departure determination unit 16 determines whether or not the host vehicle is in a lane departure state based on these input signals. The lane departure determination unit 16 sets the lane departure state flag to “1” if the vehicle is in the lane departure state as a result of the determination, and sets the lane departure state flag to “0” otherwise. In this way, the lane departure determination unit 16 generates and outputs a lane departure state flag.

A lane departure state flag from the lane departure determination unit 16 and a steering torque signal Ts from the torque sensor 6 are input to the vibration torque calculation unit 17. The steering torque signal Ts indicates the magnitude of the driver's steering torque Td.
The vibration torque calculation unit 17 first determines whether or not the host vehicle is in a lane departure state based on the lane departure state flag.
As a result of the determination, if the vehicle is in a lane departure state, the vibration torque calculator 17 calculates the vibration torque based on the steering torque signal Ts. That is, the vibration torque calculation unit 17 increases the vibration torque value as the steering torque Td increases, and decreases according to the value of the steering torque signal Ts so that the vibration torque value decreases as the steering torque Td decreases. Determine the value of. Specifically, the vibration torque calculation unit 17 stores in advance a map that stores the relationship between the steering torque signal Ts and the peak value of the vibration torque, and obtains the vibration torque using the map. For example, when the steering torque signal Ts is 0 Nm, the vibration torque peak value is 0.5 Nm, when the steering torque signal Ts is 1 Nm, it is 5 Nm, and when the steering torque signal Ts is 2 Nm, it has a numerical map. And good. In addition, what is necessary is just to obtain | require suitably the value which is not memorize | stored in a numerical map by an interpolation process. Alternatively, when the steering torque signal Ts is 0 to 0.1 Nm, the peak value of the vibration torque is constant at 0.5 Nm, and thereafter, as a proportional relationship, (steering torque signal Ts (Nm)) × 5 = (vibration torque (Nm)), the steering torque may be calculated by a function of the steering torque signal Ts.
At the same time, the vibration torque calculator 17 also calculates the vibration frequency. Specifically, the vibration frequency may be set within a range of 10 Hz to 50 Hz. The vibration frequency may be a fixed value, but the vibration frequency may be changed as appropriate according to the value of the steering torque. In that case, the vibration torque calculator 17 prepares a numerical map in advance so that the vibration frequency value increases as the steering torque increases, and the vibration frequency value decreases as the steering torque decreases. The value of the vibration frequency may be calculated according to the value of the torque signal Ts.
Note that the numerical values of the vibration torque and the vibration frequency stored in the numerical map are appropriately set according to the relationship with the assist torque and the specifications of the vehicle. Here, the specifications of the vehicle are specifications and data of individual elements constituting the vehicle, such as the shape, dimensions, weight, performance, properties, form, shape, material, and material of the vehicle.

  The assist torque calculation unit 18 based on the steering torque calculates a target assist torque for reducing the driver's steering load based on the steering torque signal Ts of the torque sensor 6. Note that, since it is not directly related to the present invention, only the assist torque based on the steering torque signal is shown here, but the assist torque for reducing the load on the driver naturally has many compensation torque calculation units. To do.

  The adder 19 adds the vibration torque calculated by the vibration torque calculation unit 17 and the target assist torque calculated by the assist torque calculation unit 18 based on the steering torque to obtain the target torque. The target torque is input to the current control unit 20.

  In the current control unit 20, a target current value indicating a current flowing to the assist motor 7 is determined based on the input target torque. Further, the current control unit 20 outputs the applied voltage E generated from the target current value to the assist motor 7. The assist motor 7 generates a motor torque Tm corresponding to the applied voltage E.

  Next, based on the flowchart of FIG. 3, the specific operation | movement regarding the steering apparatus for vehicles regarding this invention is demonstrated.

  The flow of FIG. 3 includes steps S101 to S106 between “START” and “END”.

  First, in step S101, the lane departure determination unit 16 reads the video signal Ms from the camera unit 12 and stores it in a memory (not shown). The memory may be provided in the lane departure determination unit 16, but may be provided outside the lane departure determination unit 16 as long as it is in the vehicle steering apparatus 1.

  Next, in step S102, the lane departure determination unit 16 determines a lane departure state based on the video signal Ms as to whether or not the vehicle has deviated from the lane. At this time, as described above, the lane departure determination unit 16 uses at least one of the steering angle signal θs, the vehicle speed signal Vs, the yaw rate signal γs, and the lateral acceleration signal Gs as necessary. The state may be detected, and the lane departure state may be determined using the traveling state and the video signal Ms. If it is determined in step S102 that the vehicle is not in the lane departure state, the vibration torque for the lane departure warning is not generated, so that the process proceeds to “END” and the process is terminated.

  On the other hand, if it is determined in step S102 that the vehicle is in a lane departure state, the process proceeds to the next step S103. In step S103, the vibration torque calculator 17 reads the steering torque signal Ts from the torque sensor 6 and stores it in the memory. The memory may be provided in the vibration torque calculation unit 17, but may be provided outside the vibration torque calculation unit 17 as long as it is in the vehicle steering apparatus 1. Further, the vibration torque calculation unit 17 and the lane departure determination unit 16 may share the same memory.

  In the next step S104, the vibration torque calculator 17 calculates the vibration torque for the lane departure warning according to the steering torque signal Ts. At this time, as described above, the vibration torque calculation unit 17 uses the numerical map to increase the value of the vibration torque as the steering torque increases, and to decrease the value of the vibration torque as the steering torque decreases. The value of the vibration torque is calculated according to the value of the torque signal Ts.

  In the next step S105, the assist torque calculator 18 based on the steering torque calculates a target assist torque according to the steering torque signal Ts.

  In the next step S106, the adder 19 outputs a value obtained by adding the target assist torque obtained in step S105 and the vibration torque obtained in step S104 to the current control unit 20 as a target torque. The current control unit 20 calculates a target current value for driving the assist motor 7 based on the target torque, and outputs an applied voltage E generated from the target current value to the assist motor 7. The assist motor 7 generates a motor torque Tm corresponding to the applied voltage E.

  As described above, according to the first embodiment of the present invention, the electric power steering control device 15 detects the steering torque of the driver. At this time, when the lane departure determining unit 16 determines that the vehicle is in a lane departure state, the vibration torque for the lane departure warning is determined according to the steering torque. Specifically, the vibration torque calculation unit 17 increases the vibration torque when the steering torque is large, and decreases the vibration torque when the steering torque is small. By doing so, it is possible to prevent the vibration torque for the lane departure warning from becoming relatively smaller than the assist torque. Therefore, an appropriate warning can be notified to the driver through the handle 2.

  In the first embodiment, the magnitude of the vibration torque for the lane departure warning is changed according to the steering torque. However, the present invention is not limited to this, and the vibration torque calculation unit 17 vibrates based on the assist current of the assist motor 7. The magnitude of the torque may be changed. Specifically, the vibration torque calculation unit 17 increases the vibration torque as the assist current increases, and decreases the vibration torque as the assist current decreases. In that case, since the magnitude of the vibration torque takes into account the assist current other than the steering torque, the notification based on the steering wheel vibration torque when leaving the lane is more preferable. The magnitude of the vibration torque may be changed based on both the steering torque and the assist current, or the magnitude of the vibration torque is changed by either the steering torque or the assist current. You may make it do.

In the first embodiment, the vibration torque for the lane departure warning is changed according to the driver's steering torque. However, the present invention is not limited to this, and the magnitude of the vibration torque is changed according to the driver's steering state. You may do it. Specifically, the steering state detection unit further includes a recovery state determination unit (not shown) for determining whether or not the current steering direction of the driver is a method for recovering the vehicle from the lane departure state. In the recovery state, the magnitude of the vibration torque is reduced or made zero. At this time, the vibration torque is reduced by a preset amount. Specifically, for example, the magnitude of the calculated vibration torque is multiplied by a value smaller than 1 such as 0.8, and the value is reduced accordingly, or a preset value is subtracted from the calculated vibration torque. Then, just make it smaller.
An example of the determination operation of the recovery state determination unit will be briefly described.
When the traveling state detection unit includes the camera unit 12, the recovery state determination unit detects a change in the relative position between the vehicle and the road lane based on the video signal Ms captured by the camera unit 12. Detect that the vehicle's position is changing in the opposite direction of the lane that is about to deviate and is about to return to its proper position, or is changing toward the direction of the lane that is about to deviate, By determining whether there is a high possibility that the vehicle has deviated from the lane or whether the vehicle has already deviated, it is possible to determine whether or not the vehicle is proceeding in a direction to recover from the lane departure state.
In addition, when the steering state detection unit has the torque sensor 6 that is a steering torque detection unit, the recovery state determination unit determines whether the steering state is detected from the lane departure state based on the sign of the steering torque detected by the torque sensor 6. It can be determined whether the driver is about to recover. In other words, depending on the steering direction of the driver, it can be determined whether the vehicle is going in a direction opposite to the lane where it is likely to deviate and is returning to an appropriate position or not. Whether the vehicle is moving in a direction to recover from the lane departure state can be determined based on the positive and negative signs.
As described above, the recovery state determination unit determines whether or not the driver is recovering from the lane departure state based on the video signal Ms from the camera unit 12 or the steering torque from the torque sensor 6 and tries to recover. When it is detected that the vibration torque is in a state (not shown), the vibration torque calculator 17 may reduce the vibration torque to zero or zero. As described above, in the first embodiment, if the driver's steering state and the vehicle relationship are taken into account, a more accurate lane departure warning can be notified to the driver.

  In the first embodiment, the magnitude of the vibration torque for the lane departure warning is changed according to the steering torque of the driver. However, since the way of transmission of vibration from the road surface to the handle 2 changes according to the vehicle speed, the vibration torque calculator 17 changes the magnitude of the vibration torque according to the vehicle speed detected by the traveling vehicle speed detector 11. May be. Further, the frequency component transmitted to the steering wheel 2 is limited by the tire diameter, the spring constant of the suspension, and the rigidity of the steering system. From such a background, the frequency of the vibration torque for the lane departure warning may be changed according to the vehicle speed detected by the traveling vehicle speed detection unit 11. In this way, by changing the magnitude and frequency of the vibration torque according to the vehicle speed, it is possible to notify the driver of a suitable lane departure warning at any vehicle speed.

  In the first embodiment, when the lane departure state is detected, an example in which the vibration torque is continuously superimposed until recovery from the lane departure state is described. However, the overlapping time may be considered. Specifically, the vibration torque calculation unit 17 may calculate the vibration torque so that the vibration of 15 Hz is intermittently superimposed, such as three times at 1 second intervals. In this way, not only a constant vibration torque component is applied at the time of lane departure determination, but also by intermittent operation, it is possible to enhance the notification function as a warning tactilely to the driver. Note that the time interval and the number of times of the intermittent operation may be arbitrarily determined as appropriate.

  In the first embodiment, the application of vibration torque on the assumption that the assist motor 7 is in a normal state is described. However, when the assist motor 7 has two operation modes of the normal mode and the overheat protection mode, and the output is limited by the overheat protection mode state for some reason, the vibration torque calculation unit 17 The magnitude of the torque may be changed to a value smaller than that in the normal mode. That is, the electric power steering control device has a mode detector (not shown) that detects whether the assist motor 7 is in the normal mode or the overheat protection mode, and the vibration torque calculator 17 detects the detection result of the mode detector. Accordingly, when the assist motor 7 is under overheat protection, the assist motor 7 can be protected from a failure due to overheating by reducing the vibration torque.

  In the first embodiment, the vibration torque is calculated according to the lane departure state flag. However, the lane departure state flag may be always turned on depending on the traveling state. In such a case, if a vibration torque that continuously vibrates the steering wheel is generated as a lane departure warning, the driver becomes uncomfortable. In addition, the driver gets used to the vibration torque, and the effect of the lane departure warning may be reduced. Therefore, the vibration torque calculation unit 17 has a timer for measuring the elapsed time, measures the elapsed time from the generation of the vibration torque, and when the elapsed time from the generation reaches the first threshold, It is preferable to temporarily stop the generation of torque and stop the generation of vibration torque until the elapsed time from the stop reaches the second threshold. Thus, when vibration torque continues to be generated for a certain period of time, the generation of vibration torque is temporarily stopped, and after a while, the generation of vibration torque is resumed. . As described above, when the generation of the vibration torque continues for a certain period of time, it is possible to prevent the driver from becoming uncomfortable by stopping the operation once and generating the vibration torque again. It becomes possible to prevent a reduction in the effect due to familiarity, and it is possible to enhance the warning effect to the driver more tactilely.

  Although not described in the first embodiment, the vibration torque calculation unit 17 may set upper and lower limit values for the vibration torque calculation. The vibration torque calculator 17 corrects the magnitude of the vibration torque so that the calculated magnitude of the vibration torque falls within the range from the upper limit value to the lower limit value. That is, when the magnitude of the calculated vibration torque exceeds the upper limit value, the vibration torque calculation unit 17 changes the magnitude of the vibration torque to the upper limit value, while the calculated magnitude of the vibration torque is lower limit value. If the value is lower than the value, the magnitude of the vibration torque is changed to the lower limit value. In this way, by setting the upper and lower limit values for the magnitude of the vibration torque, it becomes possible to prevent the vibration torque from becoming excessive due to some calculation failure or the like, resulting in an unstable vehicle state.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design changes can be made.

  DESCRIPTION OF SYMBOLS 1 Steering device for vehicles, 2 Handle, 3 Steering shaft, 4 Pinion gear, 5 Steering angle detection part, 6 Torque sensor, 7 Assist motor, 8 Motor gear, 9 Rack shaft, 10 Tire, 11 Traveling vehicle speed detection part, 12 Camera unit , 13 Yaw rate detection unit, 14 Lateral acceleration detection unit, 15 Electric power steering control device, 16 Lane deviation determination unit, 17 Vibration torque calculation unit, 18 Assist torque calculation unit based on steering torque, 19 Adder, 20 Current control unit.

Claims (9)

A vehicle steering device mounted on a vehicle,
The vehicle is
A steering state detector for detecting the steering state of the driver;
A driving state detection unit for detecting the driving state of the vehicle,
The vehicle steering device includes:
An assist motor for generating an assist torque for assisting the driver's steering;
A motor drive control unit that calculates a target assist torque for the assist motor based on the steering state detected by the steering state detection unit, and drives the assist motor;
A lane departure determination unit that determines whether the vehicle is in a lane departure state based on the traveling state detected by the traveling state detection unit;
A vibration torque calculation unit that calculates a vibration torque to be superimposed on the assist torque when the lane departure determination unit determines that the vehicle is in a lane departure state;
When the vibration torque calculation unit calculates the vibration torque, the motor drive control unit drives the assist motor with the target assist torque as a value obtained by adding the target assist torque and the vibration torque,
The vibration torque calculation unit changes the magnitude of the vibration torque according to the steering state detected by the steering state detection unit.
Vehicle steering system. The steering state detection unit
A steering torque detector for detecting the steering torque of the driver;
A motor current detector for detecting an assist current flowing through the assist motor,
The vibration torque calculation unit calculates the vibration torque using at least one of the steering torque detected by the steering torque detection unit and the assist current detected by the assist current detection unit as the steering state. The vehicle steering apparatus according to claim 1. The traveling state detection unit
A camera unit for photographing the front of the vehicle and outputting a video signal obtained by photographing as the running state;
The vehicle steering apparatus according to claim 1 or 2. The steering state detection unit
A recovery state determination unit that determines whether or not the current steering direction of the driver is a direction in which the vehicle recovers from a lane departure state based on the detected steering state;
When it is determined that the recovery state determination unit is in the recovery direction, the vibration torque calculation unit corrects the magnitude of the vibration torque to a smaller value by a preset amount or makes it zero.
The vehicle steering device according to any one of claims 1 to 3. The traveling state detection unit includes a traveling vehicle speed detection unit that detects a vehicle speed of the vehicle,
The vibration torque calculation unit changes the magnitude and frequency of the vibration torque according to the vehicle speed value detected by the traveling vehicle speed detection unit.
The vehicle steering apparatus according to any one of claims 1 to 4. The vehicle steering apparatus according to any one of claims 1 to 5, wherein the vibration torque calculation unit calculates the vibration torque so that the vibration torque is intermittently superimposed on the assist torque. The assist motor has a normal mode and an overheat protection mode,
The motor drive control unit includes a mode detection unit that detects whether the assist motor is in the normal mode or the overheat protection mode,
The vibration torque calculation unit is based on the detection result of the mode detection unit so that the vibration torque when the assist motor is in the overheat protection mode is smaller than the vibration torque when the assist motor is in the normal mode. Change the magnitude of vibration torque,
The vehicle steering apparatus according to any one of claims 1 to 6. The vibration torque calculation unit measures an elapsed time from the generation of the vibration torque, and interrupts the generation of the vibration torque when the elapsed time from the generation reaches a first threshold, and the elapsed time from the interruption The generation of the vibration torque is stopped until the time reaches the second threshold.
The vehicle steering apparatus according to any one of claims 1 to 7. The vibration torque calculation unit sets an upper limit value and a lower limit value for the vibration torque, limits the magnitude of the vibration torque within a range from the upper limit value to the lower limit value, and calculates the vibration torque. The vehicle steering apparatus according to any one of claims 1 to 8.

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