JP2008068783A - Steering support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering support device capable of avoiding a risk of stopping steering support even at a steep curve due to the low speed of a car when the device can perform steering support or in similar cases. <P>SOLUTION: The steering support device 10 refers to a map indicating that steering support can be executed based on a relationship between the car speed V of its own vehicle and a curve curvature 1/R. When it is determined that the steering support can be executed, the steering support device 10 calculates a required steering torque Tn and a steering support torque Ta, and causes the steering support torque Ta to be generated and a steering wheel to be steered. In this stage, the slower the car speed V of its own vehicle is, the more likely the map indicating that steering support can be executed to make it possible to execute steering support even if the curve curvature 1/R is high. Further, when the curve curvature 1/R is low, the map makes it possible to execute steering support even though the car speed V is fast. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering assist device that applies an appropriate steering torque to assist a host vehicle traveling along a traveling path.

Conventionally, by acquiring the shape of the traveling path of the host vehicle, acquiring steering torque that allows the host vehicle to travel along the traveling path, and applying the acquired steering torque to the host vehicle, A steering assist device that reduces driving load is known. Among such conventional steering assist devices, there is one in which the steering assist is interrupted in accordance with the value of the curve curvature or the curve curvature change rate (for example, clothoid coefficient) which is a parameter representing the shape of the curve. . (For example, see Patent Document 1.)
JP 2006-31553 A

  According to such a conventional steering assist device, it is determined whether or not the steering assist is possible when the host vehicle enters a sharp curve based on the curve curvature or the change rate of the curve curvature. When it is determined that the vehicle can be operated, the steering support is interrupted, an appropriate warning is given to the driver and the steering is urged so that the vehicle can travel appropriately. However, such a conventional steering assist device determines whether or not the steering assist is possible even when the vehicle is steep and the steering speed is possible because the vehicle speed of the host vehicle is low. Since the determination is based only on the rate of change of the curve curvature, the steering support is stopped and the convenience may be reduced.

The steering assist device of the present invention is made to cope with the above problem,
Vehicle speed acquisition means for acquiring the vehicle speed of the host vehicle;
Traveling road shape acquisition means for acquiring the shape of the traveling road on which the host vehicle travels;
Steering torque acquisition means for acquiring a steering torque that allows the host vehicle to travel along the travel path;
Steering assisting means for assisting traveling along a lane by applying the steering torque acquired by the steering torque acquiring means to the host vehicle;
A steering assist device comprising:
The vehicle speed of the host vehicle;
The shape of the travel path acquired by the travel path shape acquisition means;
Steering assist execution determining means for determining whether or not the steering assist means can be executed based on
The steering support execution determination means is
When the vehicle speed of the host vehicle is low, the steering assist can be executed even when the curve curvature or the shape of the travel path has a larger curve curvature change rate than when the vehicle speed is high.

  According to this, the vehicle speed of the host vehicle is acquired by the vehicle speed acquisition means, and the curve curvature or the rate of change of the curve curvature is acquired by the traveling road shape acquisition means. At this time, for example, when the acquired shape of the traveling road is a curve shape, it is necessary to apply a steering force to the own vehicle in order for the own vehicle to travel along the traveling path. Power is acquired. Here, it is determined whether or not to apply the steering torque based on the acquired vehicle speed and the shape of the travel path. If it is determined that the execution is possible, the calculated steering torque is applied. The

  Therefore, according to the above configuration, whether or not to apply the steering torque is determined based not only on the shape of the traveling road but also on the vehicle speed. When the steering assist is low and the steering assist is possible, the steering assist is executed without being stopped, and the steering assist can be performed to appropriately reduce the driver's load. Similarly, even when the vehicle speed of the host vehicle is higher than a predetermined value, if the steering support is possible because the curve is gentle, the steering support is executed without being stopped, and the driver's load is appropriately set. It is possible to provide steering assistance that can be reduced to a minimum.

in this case,
Departure possibility acquisition means for acquiring the possibility of departure that is the possibility that the host vehicle deviates from the traveling path;
The departure warning means for issuing a warning when the possibility of departure is a predetermined value or more,
With
It is preferable that the type or timing of warning by the departure warning means is changed according to whether or not the steering support means is determined as determined by the steering support execution determination means.

  According to this, when the possibility of departure of the host vehicle is acquired by the departure possibility acquisition means and the departure possibility is determined to be greater than or equal to a predetermined value, that is, when the steering assist device according to the present invention determines that the departure possibility is high. A warning is given to the driver. The type or timing of the alarm at this time is determined according to the determination result as to whether or not to apply the steering torque based on the vehicle speed and the shape of the travel path. Therefore, when there is a high possibility that the host vehicle will depart from the travel path, it is possible to avoid the host vehicle from deviating from the travel path by prompting the driver to steer by an alarm.

  Hereinafter, an embodiment of a steering assist device according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a steering assist device 10 according to this embodiment.

  This steering assist device 10 is mounted on a vehicle (the own vehicle which is an automobile). The steering support device 10 includes a steering support electronic control device (hereinafter referred to as a steering support ECU) 12, a steering support switch 14, a CCD camera 16, and an image processing electronic control device (hereinafter referred to as an image processing ECU) 18. A vehicle speed sensor 20, a yaw rate sensor 22, a meter device 24, an alarm device 26, a steering torque sensor 28, a steering electronic control device (hereinafter referred to as a steering ECU) 30, and a steering motor 32. .

  The steering assist ECU 12 is a CPU that controls each device and processes / calculates various data, a ROM that stores a program executed by the CPU, a map (lookup table), and the like, and a CPU that temporarily stores data as necessary. A general configuration including a RAM that stores data, a back-up RAM that stores data while the power is turned on, and holds the stored data while the power is shut off, and an interface including an AD converter It is a microcomputer, and provides steering assistance to the driver as necessary.

  The steering assist switch 14 is attached in the vicinity of the driver's seat in the host vehicle, and when the driver operates the steering assist switch 14, the operation content is transmitted to the ECU 12. Specifically, when the steering assist switch 14 is “ON”, steering assist control by the steering assist device 10 is executed, and when the steering assist switch 14 is “OFF”, the steering assist device 10 performs control. The steering assist control is not executed.

  The CCD camera 16 is attached to the front of the host vehicle, images the traveling road ahead of the vehicle, acquires the captured image, and transmits the acquired image to the image processing ECU 18. The image processing ECU 18 is a microcomputer having a general configuration similar to that of the steering assistance ECU 12, processes an image captured by the CCD camera 16, and transmits a processing result to the steering assistance ECU 12. Specifically, the image processing ECU 18 recognizes the lane in which the host vehicle travels based on the acquired image based on the white line of the travel path on which the host vehicle travels, and the position, curve curvature, offset angle, etc. in the lane of the vehicle. Can be obtained by calculation.

  The vehicle speed sensor 20 includes wheel speed sensors attached to the respective wheels of the host vehicle (not shown), detects the speed and stop state of the host vehicle, and transmits the detection result to the steering assist ECU 12. The yaw rate sensor 22 is attached under the center console of the host vehicle (not shown), detects the yaw rate of the host vehicle, and transmits the detection result to the steering assist ECU 12.

  The meter device 24 is attached in front of the driver's seat of the host vehicle, and turns on a notification lamp (not shown) that is a part of the configuration of the meter device 24 in response to a command to the steering assist ECU 12 to indicate to the driver the state of the host vehicle. You can be notified. Specifically, it is notified whether or not the steering assistance can be executed, the steering assistance execution state, the driver needing steering, and the like. The warning device 26 is attached in the host vehicle and outputs a buzzer sound as a warning to the driver in response to a command to the steering assist ECU 12.

  The steering torque sensor 28 detects a steering torque and a steering angle of a steering wheel (not shown) by a driver, and transmits a detection result to the steering ECU 30. The steering ECU 30 is a microcomputer having a general configuration similar to that of the steering assist ECU 12, determines the assist amount of the steering torque based on the command of the steering assist ECU 12 and the detection result by the steering torque sensor, and is driven by the steering motor 32. A signal is transmitted. The steering motor 32 generates a steering assist torque for assisting the steering operation by the driver based on a command from the steering ECU 30, and steers a steering wheel (not shown).

(Overview of operation)
Next, the outline | summary of an action | operation of the steering assistance apparatus 10 which concerns on a present Example comprised as mentioned above is demonstrated. FIG. 2 shows the area of the portion where steering assistance is possible from the relationship between the vehicle speed V of the host vehicle and the curve curvature 1 / R which is the reciprocal of the curve radius in the conventional steering assistance device. The conventional steering assist device can perform the steering assist when the vehicle speed V resulting from the braking / driving force operation or the like of the driver of the host vehicle is within the predetermined range v2 to v1 shown in FIG. Further, if the curve curvature 1 / R does not exceed the predetermined value r1, steering assistance can be performed. Thereby, it is determined based on the curve curvature 1 / R whether or not the vehicle speed V of the host vehicle, which is the operating condition, is within a predetermined range, and the steering assist is possible when the host vehicle enters the curve. When the curve curvature 1 / R exceeds r1, that is, when it is determined that the steering support is difficult, the steering support is interrupted. However, such a conventional steering assist device stops the steering assist even when the steering assist is possible because the vehicle speed V is low even if the curve curvature 1 / R exceeds r1.

  On the other hand, when the steering assist device 10 according to the embodiment of the present invention is capable of steering assist even if one of the values of the vehicle speed V and the curve curvature 1 / R is not within the predetermined range. Steering assistance can be executed. Specifically, whether or not the steering support can be executed is determined by referring to a map indicating whether or not the steering support can be executed based on the relationship between the vehicle speed V of the host vehicle and the curve curvature 1 / R as shown in FIG. Judgment was made and operation support was made when it was possible to execute. The shaded area in FIG. 3 is an area where steering assistance can be executed. At this time, the map of FIG. 3 shows that the steering assistance can be executed even when the curve curvature 1 / R is large when the vehicle speed V of the host vehicle is low, compared to when the vehicle speed V of the host vehicle is high. It is what. As shown in FIG. 3, steering assistance may be possible even if the vehicle speed V is not within the predetermined range v2 to v1, but the vehicle speed V is set to v3 determined based on the road speed limit. If it exceeds, steering assistance cannot be executed.

  According to the present invention, in the case where the conventional steering assist device cannot perform the steering assist, the vehicle speed V is higher than the predetermined value but the curve curvature 1 / R is small, and thus the steering assist is possible. Although 1 / R is larger than a predetermined value but the vehicle speed V is low, steering assistance can be performed even when steering assistance is possible. Therefore, as can be seen by comparing the hatched portions in FIG. 2 and FIG. 3, it is possible to perform steering support in more scenes than in the conventional steering support device, and reduce the driving load on the driver. be able to.

(Actual operation)
Next, the actual operation of the steering assist device 10 according to the present embodiment will be described. The steering assist ECU 12 of the steering assist device 10 according to the embodiment of the present invention is for assisting the traveling along the traveling path shown in the flowchart of FIG. 4 when the steering assist switch 14 is “ON”. A routine (steering support routine) is executed every elapse of a predetermined time.

  When the steering assist device 10 according to the present embodiment reaches a predetermined timing, the steering assist ECU 12 starts the process from step 401 of the steering assist routine, proceeds to step 402, and the vehicle speed sensor 20 determines the vehicle speed V of the host vehicle. The yaw rate W of the host vehicle is acquired by the yaw rate sensor 22, and the steering torque Tu by the driver is acquired by the steering torque sensor 28.

  Next, the steering assist ECU 12 proceeds to step 403, where the CCD camera 16 captures the traveling road and transmits the acquired image to the image processing ECU 18. Next, the steering assist ECU 12 proceeds to step 404, transmits a command to the image processing ECU 18, and extracts a pair of white lines on the travel path.

  Next, the steering assist ECU 12 proceeds to step 405 and transmits a command to the image processing ECU 18 to acquire the curve curvature 1 / R, the offset angle Δθ, and the offset amount ΔD. Specifically, the curve curvature 1 / R is the reciprocal of the curve radius of the road, and the image processing ECU 18 calculates the center line from the pair of white lines extracted in step 405, and calculates the curve radius R of the center line. And by taking the reciprocal thereof. The offset angle Δθ is a deviation angle between the traveling direction of the host vehicle and the direction of the traveling path, and the image processing ECU 18 determines the direction of the host vehicle calculated from the yaw rate W of the host vehicle and the predetermined center line of the lane in step 405. It is obtained by taking the difference between the direction of the tangent at the point of. The offset amount ΔD is the amount of deviation of the host vehicle from the center line, and the image processing ECU 18 calculates the distance between a predetermined point of the host vehicle and a tangent at a predetermined point of the center line of the lane in step 405. Get by.

  Next, the steering assist ECU 12 proceeds to step 406 and determines whether or not steering assist can be executed. Specifically, the determination is made by referring to a map indicating whether or not the steering assistance can be executed from the relationship between the vehicle speed V of the host vehicle and the curve curvature 1 / R as shown in FIG. Steering support is feasible when the vehicle speed V and the curve curvature 1 / R of the host vehicle are within the shaded area of the map of FIG. 3, and steering assistance is performed when the vehicle speed is outside the shaded area. It becomes impossible. In the map of FIG. 3, steering support can be executed even when the curve curvature is high as the vehicle speed of the host vehicle is low, and conversely, steering support can be executed even when the vehicle speed is high when the curve curvature is low. It has become.

If “Yes” in step 406, that is, if it is determined that execution of steering assistance is possible, the steering assistance ECU 12 proceeds to step 407 so that the host vehicle travels along the traveling path. A necessary steering torque Tn, which is a necessary torque, is calculated by the following equation (1).
Tn = k1 * (V * V / R) + k2 * Δθ + k3 * ΔD (1)
The coefficients k1, k2, and k3 are predetermined values.

  Next, the steering assist ECU 12 proceeds to step 408, and the steering ECU 30 calculates the steering assist torque Ta so as to achieve the necessary steering torque Tn (by the driver obtained from the necessary steering torque Tn by the steering torque sensor 28). The steering torque Tu is reduced), and a driving signal is transmitted to the steering motor 32 so that the steering assist torque is applied, whereby the steering assist torque Ta is generated and the steering wheel is steered so that the vehicle travels along the travel path. It can be performed.

  Next, the steering assist ECU 12 proceeds to step 409 to determine the possibility of departure. Specifically, based on the current position and traveling state of the host vehicle (for example, the vehicle speed V acquired by the vehicle speed sensor 20 and the steering torque Tu by the driver acquired by the steering torque sensor 28), a predetermined expected departure time t1. A subsequent expected arrival position is obtained, and from this and the position of the pair of white lines acquired by the image processing ECU 18, it is determined whether or not the host vehicle is located within the range of the pair of white lines at the estimated departure time.

  When it is determined “Yes” in step 409, that is, when it is determined that there is a possibility of departure, the steering assist ECU 12 proceeds to step 410 so that the driver recognizes that there is a possibility of departure and prompts steering. Then, the notification lamp of the meter device 26 is turned on, the alarm buzzer is sounded by the alarm device 28, the process proceeds to step 413, and this routine is once terminated.

If “No” in step 406, that is, if it is determined that the execution of the steering support is not possible, the steering support ECU 12 proceeds to step 411 and determines the possibility of departure.
Specifically, based on the current position and traveling state of the host vehicle, an expected arrival position after a predetermined expected departure time t2 is obtained, and the host vehicle is determined from this and the position of the pair of white lines acquired by the image processing ECU 18. It is determined whether or not is located within the range of a pair of white lines at the estimated departure time. Note that t2 is larger than t1. As a result, when steering assistance is not performed as compared with the case where steering assistance is performed, a warning is issued to recognize that the driver is more likely to avoid departure earlier, that is, when the estimated departure time is longer. be able to.

If “Yes”, that is, it is determined that there is a possibility of departure in step 411, the steering assist ECU 12 proceeds to step 412 to make the driver recognize that there is a possibility of departure and to prompt steering. Then, the notification lamp of the meter device 26 is turned on, the alarm buzzer is sounded by the alarm device 28, the process proceeds to step 413, and this routine is once terminated. The flashing pattern of the notification lamp and the alarm pattern of the alarm buzzer at this time are different from the alarm performed in step 410. For example, alarm 2 in step 412 is a situation where steering assistance is not performed and is more urgent than alarm 1 in step 410, so even if the flashing speed of the notification lamp is increased and the volume of the alarm buzzer is increased. good. Accordingly, an appropriate warning can be given to the driver depending on whether or not steering assistance is possible. If it is determined “No” in step 411, that is, if it is determined that there is no possibility of departure, the process proceeds to step 413 as it is and this routine is once ended.

  As described above, the steering assist device 10 according to the embodiment of the present invention refers to the map indicating whether or not the steering assist can be executed from the relationship between the vehicle speed V of the host vehicle and the curve curvature 1 / R, When it is determined that the steering assist is feasible, the necessary steering torque Tn and the steering assist torque Ta are calculated, the steering assist torque Ta is generated, and the steering wheel is steered so that the vehicle follows the travel path. Makes it possible to carry out running. As a result, the vehicle speed V is higher than a predetermined value, which is a conventional steering assist condition, but the curve curvature 1 / R is small, so that steering assist is possible, and the curve curvature 1 / R is a predetermined value, which is a conventional steering assist condition. However, the vehicle speed V is low, so that the steering support can be performed even when the steering support is possible, and the steering support is stopped even when the steering support is possible. Can be avoided.

  The present invention is not limited to the above-described embodiment, and various modifications as described below can be adopted within the scope of the present invention.

For example, the steering assist device 10 according to the above embodiment uses the curve curvature 1 / R as a parameter representing the traveling road shape. However, if the parameter is based on the traveling road shape, the curve curvature 1 / R is not necessarily required. There is no. For example, the rate of change of curve curvature (eg clothoid coefficient),
May be used. When comparing on the same length of travel road, the greater the rate of change of the curve curvature, the more difficult it is to provide steering assistance. Therefore, the present invention is applied by determining whether or not steering assistance can be executed by referring to a map indicating whether or not steering assistance can be executed from the relationship between the curve curvature change rate and the vehicle speed in consideration of this characteristic. Can do.

  In addition, the steering assist device 10 according to the above embodiment acquires the curve curvature and determines whether or not the steering assist can be performed. However, the curve curvature or the curve curvature change rate may not be directly acquired without acquiring the curve curvature or the curve curvature change rate directly. What is necessary is just to be able to acquire that it is the shape of a running road from which a curve curvature changes. For example, whether or not steering assistance can be executed may be determined from a curve diameter, a curve radius, a lane width, a cant, map information, and the like.

  Further, the steering assist device 10 according to the above-described embodiment refers to whether or not the steering support can be executed by referring to a map indicating whether or not the steering support can be executed from the relationship between the vehicle speed V of the host vehicle and the curve curvature 1 / R. However, it is only necessary to determine whether or not the steering assistance can be performed based on the vehicle speed of the host vehicle and the shape of the travel path, and it is not always necessary to use a map. For example, if the vehicle speed of the own vehicle and the rate of change of the curve curvature are substituted into a predetermined judgment formula including the rate of change of the curve curvature, and the value does not exceed the predetermined value Steering assistance may be performed, and steering assistance may be performed when a predetermined value is exceeded.

  Further, the steering assist device 10 according to the above embodiment captures the shape of the traveling road by photographing the traveling road with the CCD camera 16 and performing data processing with the image processing ECU 18. The travel route on which the host vehicle travels may be obtained using a navigation system or the like, or a plurality of acquisitions such as a travel route acquisition result by the CCD camera 16 and a travel route result using the navigation system may be obtained. The results may be combined. Thereby, the precision of the acquisition result of a travel path can be made high.

  Further, the steering assist device 10 according to the above embodiment calculates the steering assist torque Ta by subtracting the steering torque Tu by the driver acquired by the steering torque sensor 28 from the required steering torque Tn. The present invention can also be applied to a vehicle that performs driving. Specifically, when there is no steering torque by the driver, that is, when the steering torque Tu is 0, the steering assist torque Ta is equal to the necessary steering torque Tn, and the steering assist torque Ta is applied to the host vehicle. Even if there is no operation by the driver, it is possible to travel along the traveling path.

  Furthermore, although the steering assist device 10 according to the present embodiment assumes a change in the vehicle speed due to the braking / driving force operation by the driver, the present invention is not limited to this and is also applied to a case where the vehicle speed is changed by another method. be able to. For example, by applying the present invention to a vehicle that obtains information about the surroundings of the host vehicle (road surface condition, weather, distance and speed with a preceding vehicle, etc.) and performs control to change the vehicle speed based on the obtained information. , Avoiding the possibility of stopping the steering support even if the speed, the curve curvature, and the curve curvature change rate at which the steering support control can be originally performed can be avoided, and it is possible to increase the opportunities for executing the steering support control. Become. In addition, this makes it possible to increase the vehicle speed when the curve curvature and the rate of change of the curve curvature are small. Therefore, the upper limit value of the set vehicle speed, which is the vehicle speed region that can be controlled, is increased compared to the conventional case. It can also be made. Therefore, it is possible to simultaneously reduce the load of the driver's vehicle speed changing operation and steering operation in more scenes.

It is the schematic of the steering assistance apparatus 10 which concerns on embodiment of this invention. It is a figure which shows the propriety of execution of steering assistance from the relationship between the vehicle speed V of the own vehicle and the curve curvature 1 / R in the conventional steering assistance apparatus. It is a figure which shows the propriety of execution of steering assistance from the relationship between the vehicle speed V of the own vehicle and the curve curvature 1 / R in the steering assistance apparatus 10 which concerns on embodiment of this invention. It is the flowchart which showed the routine which CPU of the electronic control apparatus 12 for steering assistance of the steering assistance apparatus 10 which concerns on embodiment of this invention performs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Steering assistance apparatus, 12 ... Steering assistance electronic control apparatus (steering assistance ECU), 14 ... Steering assistance switch, 16 ... CCD camera, 18 ... Electronic control apparatus for image processing (image processing ECU), 20 ... Vehicle speed sensor, 22 ... Yaw rate sensor, 24 ... Meter device, 26 ... Alarm device, 28 ... Steering torque sensor, 30 ... Electronic control device for steering (steering ECU), 32 ... Steering motor

Claims (2)

Vehicle speed acquisition means for acquiring the vehicle speed of the host vehicle;
Traveling road shape acquisition means for acquiring the shape of the traveling road on which the host vehicle travels;
Steering torque acquisition means for acquiring a steering torque that allows the host vehicle to travel along the travel path;
Steering assisting means for assisting traveling along a traveling path by applying the steering torque acquired by the steering torque acquiring means to the host vehicle;
A steering assist device comprising:
The vehicle speed of the host vehicle;
The shape of the travel path acquired by the travel path shape acquisition means;
Steering assist execution determining means for determining whether or not the steering assist means can be executed based on
The steering support execution determination means is
Steering characterized in that the steering support can be executed even when the vehicle speed of the host vehicle is low and the shape of the travel path has a larger curve curvature or a change rate of the curve curvature than when the vehicle speed is high. Support device. Departure possibility acquisition means for acquiring the possibility of departure that is the possibility that the host vehicle deviates from the traveling path;
The departure warning means for giving a warning when the possibility of departure is within a predetermined range;
The steering assist device according to claim 1, comprising:
A steering support device, wherein the type or timing of warning by the departure warning means is changed according to whether or not the steering support means is determined as determined by the steering support execution determination means.

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