JP3725090B2 - Vehicle steering control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering control device that recognizes a traveling lane and performs steering control of the vehicle.
[0002]
[Prior art]
Conventionally, many inventions have been filed for detecting steering lanes by detecting lane markings in front of a vehicle and performing steering control so that the vehicle can travel along the traveling lane. Several applications have also been filed regarding a method of setting a vehicle front gazing distance that is used as an input and obtains vehicle relative position information with respect to a target lane. For example, in Japanese Patent Laid-Open No. 03-192500, the position of the lane marking is detected by image processing, the gaze distance is reset according to the detection reliability of the image processing, and steering control becomes unstable due to erroneous recognition or the like. To prevent that.
[0003]
Further, in Japanese Patent Laid-Open No. 10-167100, by detecting the curvature radius in front of the vehicle and changing the forward gaze distance in accordance with the curvature radius, the detection point deviates from the detection visual field, and the steering control amount cannot be obtained. The case is avoided.
[0004]
[Problems to be solved by the invention]
However, in Japanese Patent Laid-Open No. 03-192500 and Japanese Patent Laid-Open No. 10-167100, the forward gaze distance is changed for convenience of the sensor side for recognizing the traveling lane so that the original steering control is optimized. It is not set. Therefore, when the method for setting the forward gaze distance as described above is performed, for example, the lateral deviation with respect to the target lane becomes larger than when the front gaze distance is set for optimal steering control. It was. Note that the optimum steering control mentioned here is control that minimizes a control deviation such as a lateral deviation with respect to the target lane.
[0005]
The present invention has been made to solve the above-described problems, and the forward gaze distance is set so that the front gaze distance is set so as to achieve optimum steering control to reduce the lateral deviation with respect to the target lane. It is what.
[0006]
[Means for Solving the Problems]
A vehicle steering control device according to the present invention includes a relative position information acquisition unit that acquires relative position information of a vehicle with respect to a traveling lane at a set forward gazing distance, and vehicle steering control using the acquired relative position information. In the vehicle steering control device including the steering control means for performing the above, the forward gaze distance is changed and set according to the delay of the steering control system .
[0007]
The vehicle comprises in ahead distance is set, and the relative position information obtaining means for obtaining relative positional information of the vehicle with respect to the travel lane, the steering control means for steering control of the vehicle using the acquired relative position information In the steering control device for a vehicle, the forward gaze distance is set by changing the vehicle speed of the host vehicle and the delay of the steering control system.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a vehicle steering control apparatus according to Embodiment 1 of the present invention. Reference numeral 1 denotes relative position information acquisition means for acquiring relative position information with respect to the traveling lane. In this relative position information acquisition means 1, the lateral deviation in the lane and the lane inclination calculation means 1a calculate the lateral deviation of the center of gravity of the vehicle with respect to the target lane and the inclination of the vehicle center axis with respect to the target lane.
[0009]
Here, the “lateral deviation with respect to the target lane” and the “inclination of the vehicle center axis with respect to the target lane” will be described with reference to FIG. FIG. 2 is a diagram illustrating “lateral deviation with respect to the target lane” and “inclination of the vehicle center axis with respect to the target lane” at the forward gaze distance. In the figure, reference numeral 5 denotes the host vehicle, where the forward direction of the host vehicle at that position is represented by the x axis and the direction perpendicular thereto is represented by the y axis. Reference numeral 6 denotes a lane marking representing a traveling lane, and reference numeral 7 denotes a target lane to be traced by the host vehicle. The forward gaze distance is represented here by 8, the “lateral deviation with respect to the target lane” at this forward gaze distance is represented by 9, and the “tilt of the vehicle center axis with respect to the target lane” is represented by 10. In the first embodiment, these two pieces of information are used as control inputs for steering control.
[0010]
The front gaze distance for calculating the lateral deviation with respect to the target lane and the inclination of the vehicle center axis with respect to the target lane described above is set by the front gaze distance setting means 1b. This front gaze distance is determined by the steering control system. And the vehicle speed of the host vehicle obtained by the vehicle speed detection means 2 is set. A detailed setting method will be described later. The steering control means 3 uses the lateral deviation with respect to the target lane acquired by the relative position information acquisition means 1 and the inclination of the vehicle center axis with respect to the target lane so that the host vehicle travels along the traveling lane, Alternatively, the steering angle is calculated, and the steering actuator 4 is controlled using the calculated steering torque or steering angle.
[0011]
A method for calculating the forward gaze distance according to the vehicle speed of the host vehicle and the delay of the steering control system will be described in detail. First, the relationship between the forward gaze distance and the steering performance when the steering control system delay or the vehicle speed changes is shown. However, the steering performance here refers to a lateral deviation at the center of gravity of the vehicle with respect to the target lane. FIG. 3 shows the relationship between the forward gaze distance and the steering performance when the delay of the steering control system is changed, and FIG. 4 shows the relationship between the front gaze distance and the steering performance when the vehicle speed is changed. Regardless of whether the delay of the steering control system is changed or the vehicle speed is changed, the relationship between the forward gaze distance and the steering performance is a downwardly convex graph.
[0012]
First, the relationship between the forward gaze distance Ld and the steering performance when the delay Td of the steering control system is changed will be described. When the vehicle speed is constant and the delay time Td of the steering control system is set to a certain value T1, T2, T3 (T1 <T2 <T3), the steering performance is the best, that is, the lateral deviation e with respect to the target lane is the smallest There is a forward gaze distance Ld. The minimum value of the lateral deviation increases as the delay time of the steering control system increases (T1 <T2 <T3). 11 is a characteristic curve showing the relationship between the forward gaze distance Ld and the lateral deviation e with respect to the target lane when Td = T1, 12 when Td = T2, and 13 when Td = T3. It shows that there is a forward gaze distance Ld that minimizes the lateral deviation e with respect to the lane. Using the relationship between the delay time Td of the steering control system in FIG. 3 and the optimum forward gaze distance Ld (the forward gaze distance Ld with respect to the downwardly convex vertex), the front gaze distance Ld is set according to the delay time Td of the steering control system. By changing it, the lateral deviation e with respect to the target lane can be minimized.
[0013]
On the other hand, the relationship between the forward gaze distance Ld and the steering performance when the vehicle speed is changed will be described. When the delay of the steering control system is constant and the vehicle speed V is determined to a certain value V1, V2, V3 (V1 <V2 <V3), the steering performance is the best, that is, the lateral deviation e with respect to the target lane is minimum. There is a forward gaze distance Ld. The minimum value of the lateral deviation increases as the vehicle speed increases. 21 is a characteristic curve showing the relationship between the forward gaze distance Ld and the lateral deviation e with respect to the target lane when V = V1, 22 is V = V2, and 23 is V = V3. It shows that there is a forward gaze distance Ld that minimizes the lateral deviation e with respect to the lane.
[0014]
That is, when the steering control system is designed and the delay of the control system is obtained, the relationship between the forward gaze distance Ld and the lateral deviation e with respect to the target lane when the vehicle speed V is changed as shown in FIG. A set is required. Using the relationship between the obtained forward gaze distance Ld and the lateral deviation e with respect to the target lane, the relationship between the optimum forward gaze distance Ld with respect to each vehicle speed V is obtained. This relationship is shown in the graph (characteristic curve) of FIG. FIG. 5 is a diagram showing a characteristic curve 31 showing the relationship between the vehicle speed V and the optimum forward gaze distance Ld when the delay of the steering control system is fixed (when the vehicle type is fixed). When actually performing the steering control of the vehicle with the vehicle steering control device of FIG. 1, a characteristic curve indicating the relationship between the vehicle speed V and the optimum forward gaze distance Ld of FIG. By using the curve and changing the forward gaze distance Ld according to the vehicle speed V of the host vehicle, the lateral deviation e with respect to the target lane can be minimized.
[0015]
The delay value of the steering control system is almost determined by the vehicle type. In FIG. 5 showing the relationship between the vehicle speed V and the optimum forward gazing distance Ld, when the delay of the steering control system increases, the downwardly convex portion shifts to the right side as it increases. Furthermore, the entire characteristic curve is shifted upward. Therefore, it is necessary to obtain this characteristic curve for each vehicle type. If the characteristic curve of FIG. 5 is held for each vehicle type, the vehicle steering control device of the present invention can be mounted on any vehicle type.
[0016]
Embodiment 2. FIG.
In the first embodiment, the front gaze distance is set according to the characteristic curve of “vehicle speed−optimal front gaze distance”, and the relative position information at the front gaze distance is directly obtained to perform the steering control. However, within the relative position information acquisition means, a plurality of candidate lane marking points are detected, a road model represented by a polynomial is identified using the detected plurality of lane markings, and the relative position information at the forward gaze distance is obtained. You may obtain | require from the formula of this road model.
[0017]
The configuration and operation of the second embodiment will be described. FIG. 6 is a block diagram showing a vehicle steering control apparatus according to Embodiment 2 of the present invention. Reference numeral 41 denotes relative position information acquisition means for acquiring relative position information of the host vehicle with respect to the traveling lane. In the relative position information acquisition unit 41, first, a lane marking candidate point in a preset search line is detected by a search line candidate point detection unit 41a. The road model identification unit 41b identifies the parameters of the road model described by a polynomial based on the detected lane marking candidate points. On the other hand, the forward gaze distance setting unit 41c uses the vehicle speed V acquired by the vehicle speed detection unit 42 to set the optimum front gaze distance Ld that minimizes the lateral deviation e with respect to the target lane, as in the first embodiment. Ask. Based on the road model identified by the road model identification unit 41b and the front gaze distance Ld obtained by the front gaze distance setting unit 41c, the control input value calculation unit 41d determines the lateral deviation with respect to the target lane at the front gaze distance and the vehicle. The inclination of the central axis with respect to the target lane is calculated, and the steering control means 43 obtains the steering torque or steering angle, which is the operation amount, using the obtained control input, and actually controls the steering actuator 44.
[0018]
The above-described “search line” and “road model” will be briefly described. Assuming that the search line is an image obtained when the front of the vehicle is imaged as shown in FIG. 7, the search line is set as 51, for example. Candidate points for lane marking are detected on the search line 51 indicated by the search line 51, and the detected candidate points are shown as 52a and 52b in FIG. 8, for example. A road model is a polynomial representing a road shape, and is represented by, for example, etc. The parameters a, b, and c are identified by a least square method using a plurality of lane marking candidate points. 53 shows this road model, and FIG. 9 shows this road model in a top view. By obtaining the road model and the forward gaze distance Ld (indicated by 57), the lateral deviation 55 on the line 54 indicating the straight line x = Ld and the angle 56 formed by the vehicle center axis with respect to the target lane are obtained. The relative positional relationship of the traveling lane with respect to the vehicle, that is, the relative positional relationship of the host vehicle with respect to the traveling lane is obtained.
[0019]
As described above, since the plurality of lane marking candidate points are detected and the relative position information at the forward gaze distance is calculated from the road model identified using the plurality of lane marking candidate points, as in the first embodiment. The accuracy is higher than the relative position information acquired at a single point, and thus steering control can be performed more accurately.
[0020]
【The invention's effect】
As described above, according to the vehicle steering control device of the present invention, the relative position information acquisition means for acquiring the relative position information of the vehicle with respect to the traveling lane at the set forward gaze distance, and the acquired relative position information In the vehicle steering control device including the steering control means for performing steering control of the vehicle using the steering wheel, the forward gaze distance is changed and set according to the delay of the steering control system. Since the forward gaze distance is changed according to the distance, the lateral deviation with respect to the target lane can be kept small, and the driver can perform comfortable steering control.
[0021]
The vehicle comprises in ahead distance is set, and the relative position information obtaining means for obtaining relative positional information of the vehicle with respect to the travel lane, the steering control means for steering control of the vehicle using the acquired relative position information In the steering control device for a vehicle, the forward gaze distance is changed and set according to the vehicle speed of the own vehicle and the delay of the steering control system, so that the delay of the steering control system is considered in addition to the vehicle speed of the own vehicle. Thus, the forward gaze distance becomes more appropriate, and the lateral deviation with respect to the target lane can be further reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a vehicle steering control apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram illustrating a lateral deviation with respect to a target lane and an angle formed by a vehicle center axis with respect to the target lane at a forward gaze distance.
FIG. 3 is a curve diagram showing a relationship between a forward gaze distance Ld and a lateral deviation e with respect to a target lane when the delay of the steering control system is changed.
FIG. 4 is a curve diagram showing a relationship between a forward gaze distance Ld and a lateral deviation e with respect to a target lane when the vehicle speed is changed.
FIG. 5 shows the relationship between the vehicle speed V and the optimum forward gaze distance Ld when the delay of the steering control system is fixed.
FIG. 6 is a block diagram showing a vehicle steering control apparatus according to Embodiment 2 of the present invention.
FIG. 7 is a diagram showing search lines for searching for lane marking candidate points with respect to an image ahead of the vehicle.
FIG. 8 is a diagram illustrating a road model identified as a detected lane marking candidate point.
FIG. 9 is a diagram when a road model is viewed from above.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Relative position information acquisition means 1a Lateral position in lane and lane inclination calculation means 1b Forward gaze distance setting means 2 Vehicle speed detection means 3 Steering control means 4 Steering actuator 5 Self-vehicle 6 Lane marking indicating driving lane 7 Self-vehicle should be traced Target lane 8 Forward gaze distance 9 Lateral deviation with respect to target lane 10 Angle formed by vehicle center axis with respect to target lane 41 Relative position information acquisition means 41a Search line candidate point detection means 41b Road model identification means 41c Forward gaze distance setting means 41d control input calculating means 42 vehicle speed detecting means 43 steering control means 44 steering actuator 51 search line 52a, 52b lane marking candidate point 53 road model 54 straight line x = Ld
55 The lateral deviation of the vehicle at the forward gaze distance using the road model 56 The angle 57 made by the vehicle center axis with respect to the target lane using the road model 57 The forward gaze distance.

Claims (2)

  Steering for a vehicle comprising: relative position information acquisition means for acquiring relative position information of the vehicle with respect to the traveling lane at a set forward gaze distance; and steering control means for performing steering control of the vehicle using the acquired relative position information In the control device, the vehicle steering control device is characterized in that the forward gaze distance is set in accordance with a delay of a steering control system.   Steering for a vehicle comprising: relative position information acquisition means for acquiring relative position information of the vehicle with respect to the traveling lane at a set forward gaze distance; and steering control means for performing steering control of the vehicle using the acquired relative position information In the control device, the vehicle steering control device is characterized in that the forward gaze distance is set by changing according to the vehicle speed of the host vehicle and the delay of the steering control system.

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