JP6486605B2 - Steering control device - Google Patents

Description

  The present invention relates to a steering control device that performs steering control of a vehicle.

  Conventionally, there is a steering control device that performs steering control of a vehicle (see, for example, Patent Document 1). This steering control device calculates a target position based on image data of a road surface in front of the vehicle imaged by a camera installed at the front end of the vehicle, calculates a predicted position based on the current vehicle speed and yaw rate, The difference between the target position and the predicted position is calculated. Then, steering control is performed based on the calculated target steering angle.

JP 2013-023051 A

  By the way, one vehicle manufacturer manufactures not only a single vehicle type vehicle but also a different vehicle type vehicle. In such a case, the same steering control device may be mounted on vehicles of different vehicle types from the viewpoint of cost reduction.

  However, if the wheelbase is different depending on the vehicle type, the turning angle of the vehicle varies depending on the Ackermann geometry while the curve is in progress. The Ackermann geometry means that when the vehicle turns at a low vehicle speed at which centrifugal force can be ignored, the wheels must turn around a common point so that the wheels do not slip. When the turning angle of the vehicle is different, since the imaging direction of the camera is different, the target position calculated based on the image data captured by the camera is also different. On the other hand, the vehicle speed and the yaw rate generated in the vehicle are the same even if the turning angle of the vehicle is different. For this reason, when the same steering control device is installed in vehicles with different wheel bases, there is a problem that a difference occurs between the target position and the estimated position, and the same position cannot be traveled.

  Patent Document 1 describes that the target steering angle is calculated in consideration of the vehicle weight and the cornering power of the front wheels in order to stably travel to the target position even when the dynamic characteristics of the vehicle fluctuate. ing. However, since the thing of patent document 1 does not respond | correspond to the vehicle from which a vehicle type differs, it cannot drive the same position to the vehicle from which a vehicle type differs.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steering control device that can run the same position even in vehicles of different vehicle types.

  A steering control device according to the present invention is a steering control device that performs steering control of a vehicle, and is installed in a vehicle and acquires lane information in front of the traveling direction of the vehicle, and acquires vehicle motion information. A motion information acquisition unit, a target position calculation unit that calculates a target position of a future vehicle based on the lane information acquired by the lane information acquisition unit, and a current vehicle motion information acquired by the motion information acquisition unit An estimated position calculation unit that calculates an estimated position of a future vehicle, a correction unit that corrects the target position calculated by the target position calculation unit, and steering control that performs vehicle steering control based on the difference between the target position and the estimated position A section.

  In the steering control device according to the present invention, the steering control unit performs the steering control based on the difference between the target position and the estimated position, but the target position can be corrected by the correction unit. Thereby, even if the target position differs depending on the vehicle type, the target position can be corrected according to the vehicle type, so that the same position can be traveled even in vehicles of different vehicle types.

  In one embodiment, the correction unit may correct the target position calculated by the target position calculation unit according to the wheelbase of the vehicle. Since the target position varies depending on the wheel base of the vehicle, the correction accuracy of the target position can be improved by correcting the target position according to the wheel base of the vehicle.

  In one embodiment, the motion information acquisition unit may acquire speed and yaw rate as vehicle motion information. Since the estimated position can be calculated based on the speed and the yaw rate, the estimated position can be appropriately calculated by acquiring the speed and yaw rate as the motion information of the vehicle.

  According to the present invention, the same position can be traveled even by vehicles of different vehicle types.

It is a block diagram which shows schematic structure of the steering control apparatus which concerns on embodiment. It is the schematic which shows an example of a vehicle of a different vehicle type. It is a figure which shows the imaging direction of the imaging device mounted in each vehicle shown in FIG. It is a figure for demonstrating the deviation | shift amount of the target position in a vehicle of a different vehicle type. It is a figure which shows the control logic for calculating a target steering angle. It is a flowchart which shows the processing operation of a steering control apparatus.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected about the element which is the same or it corresponds in each figure, and the overlapping description is abbreviate | omitted.

  The steering control device according to the present embodiment performs vehicle steering control on behalf of the driver or as driving assistance for the driver when the driver becomes unable to drive due to illness or the like. Examples of the vehicle steering control include lane keeping that holds the vehicle in the lane so as not to deviate from the currently traveling lane, and lane change from the currently traveling lane to the lane on the shoulder side. . In the following description, a case where lane keeping is performed as vehicle steering control will be described.

  FIG. 1 is a block diagram illustrating a schematic configuration of the steering control device according to the embodiment. As shown in FIG. 1, a steering control device 1 according to the embodiment is a device that performs vehicle steering control by performing rotational drive control of a steering system 2, and includes a lane information acquisition unit 3 and a motion information acquisition unit 4. And a control unit 5.

  In the steering system 2, a steering wheel 23 on which a driver performs a steering operation is connected to a steering shaft 22 connected to a gear box 21 connected to a steering wheel. The steering shaft 22 can be rotationally driven by the rotational drive device 24. The rotation drive device 24 is configured by an electric motor such as a motor. The rotational drive device 24 and the steering shaft 22 are connected by a gear mechanism such as a planetary gear, and the steering shaft 22 can be rotationally driven by the rotational drive device 24.

  The lane information acquisition unit 3 is mounted on the vehicle and acquires lane information ahead of the vehicle in the traveling direction. The lane information is information on left and right lane lines that divide the lane, and is information on left and right lane lines that divide the lane in which the host vehicle travels and the lane adjacent to the lane. The lane line information can be expressed by, for example, the lane line coordinate information on the coordinate axis centered on the host vehicle. Although the mounting position of the lane information acquisition part 3 is not specifically limited, By mounting in the front-end part of a vehicle, the lane information ahead of the advancing direction of a vehicle can be acquired appropriately. As the lane information acquisition unit 3, an imaging device such as a camera or various radars can be used. When an imaging device is used as the lane information acquisition unit 3, the lane information acquisition unit 3 performs image analysis on image data captured by the imaging device, for example, extracts a lane line, and the vehicle progresses from the extracted lane line. Lane information ahead in the direction can be acquired. When a radar is used as the lane information acquisition unit 3, the lane information acquisition unit 3 can detect, for example, a lane line by the radar and acquire lane information ahead of the vehicle in the traveling direction from the extracted lane line. . In the following description, a case where an imaging device is used as the lane information acquisition unit 3 will be described. Then, the lane information acquisition unit 3 transmits the acquired lane information to the control unit 5.

  The exercise information acquisition unit 4 acquires vehicle exercise information. The motion information acquisition unit 4 acquires speed and yaw rate generated in the vehicle as motion information. The exercise information acquisition unit 4 may acquire information other than speed and yaw rate as exercise information. The vehicle speed can be obtained, for example, by detecting the rotational speed of each wheel and calculating the vehicle speed from the rotational speed of each wheel. As the yaw rate, the yaw rate generated in the vehicle can be obtained by the yaw rate sensor. Then, the exercise information acquisition unit 4 transmits the acquired exercise information to the control unit 5.

  The control unit 5 performs rotation drive control of the rotation drive device 24 of the steering system 2 based on information transmitted from the lane information acquisition unit 3 and the movement information acquisition unit 4. Therefore, the control unit 5 includes functions of an automatic steering necessity determination unit 51, a target position calculation unit 52, an estimated position calculation unit 53, a correction unit 54, and a steering control unit 55. The control unit 5 is mainly configured by an arithmetic device such as a CPU and a storage device such as a memory, and performs various controls according to various programs stored in advance.

  The automatic steering necessity determination unit 51 has a function of determining whether or not to perform vehicle steering control on behalf of the driver or as driving assistance for the driver. For example, when the driver becomes unable to drive due to a sudden illness or the like, it is determined that the steering control of the vehicle is performed. Whether or not the driver is unable to drive due to sudden illness or the like may be determined based on, for example, the operation of an emergency button installed in the driver's seat or passenger's seat, and the driver imaged by a camera installed in the passenger compartment The determination may be made based on the analysis result of the face image.

  The target position calculation unit 52 has a function of calculating a target position of a future vehicle based on the lane information acquired by the lane information acquisition unit 3. The future target position of the vehicle is the target position of the vehicle after a predetermined time (after τ time), and can be, for example, the target position of the vehicle after 5 seconds. When the lane keeping steering control is performed, the target position calculation unit 52 sets the center in the width direction of the currently traveling lane as the target position. When steering control for lane change is performed, the center in the width direction of the lane adjacent to the shoulder side of the currently traveling lane is set as the target position. Note that the target position does not necessarily need to be in the center in the width direction of the lane, and may be a position close to the left lane line side or a position close to the right lane line side.

  The estimated position calculation unit 53 has a function of calculating an estimated position of a future vehicle based on the current vehicle movement information acquired by the movement information acquisition unit 4. The estimated position of the future vehicle is the estimated position of the vehicle after a predetermined time (after τ time), like the target position of the future vehicle, and may be the estimated position of the vehicle after 5 seconds, for example. it can.

Here, a coordinate axis in which the longitudinal direction of the vehicle is the x axis and the direction orthogonal to the x axis (the lateral direction of the vehicle) is the y axis is considered. Further, the vehicle speed V, the yaw rate gamma, the estimated position of the vehicle after τ seconds in the y-axis direction and y _t, the estimated position of the vehicle after τ seconds in the x-axis direction l _t. Then, when the estimated position calculation unit 53 acquires the vehicle speed and the yaw rate as the vehicle motion information from the motion information acquisition unit 4, the estimated position calculation unit 53 calculates the following equations (1) and (2) to calculate the vehicle position after τ seconds. and it calculates the estimated position _{y t} and the estimated position _{l t.} Incidentally, the calculated estimated position y _t and the estimated position l _t is the estimated position of the vehicle after τ seconds.
y _t = τ ² · V · γ / 2 (1)
l _t = τ · V (2)

  The correction unit 54 has a function of correcting the target position calculated by the target position calculation unit 52. In other words, since the target position calculated by the target position calculation unit 52 differs depending on the vehicle type, the correction unit 54 sets a correction coefficient for the target position according to the vehicle type, and the target position calculation unit 52 uses the set correction coefficient. The target position calculated by is corrected.

  Here, the correction of the target position by the correction unit 54 will be described with reference to FIGS. FIG. 2 is a schematic diagram illustrating an example of a vehicle of a different vehicle type. FIG. 3 is a diagram showing the imaging direction of the imaging device mounted on each vehicle shown in FIG. FIG. 4 is a diagram for explaining a deviation amount of a target position in vehicles of different vehicle types.

  First, consider the vehicle A shown in FIG. 2A and the vehicle B shown in FIG. 2B. Vehicle A and vehicle B have the same overall length, but vehicle A is a front 1 axle x rear 2 axle triax vehicle (FR), and vehicle B is a front 2 axle x rear biax 4 axle vehicle (FW). Thus, the wheel base WB2 of the vehicle B is longer than the wheel base WB1 of the vehicle A.

  3, since the turning angle is different between the vehicle A and the vehicle B as shown in FIG. 3, the imaging direction a1 of the imaging device mounted on the vehicle A and the imaging of the imaging device mounted on the vehicle B are illustrated. Unlike the direction b1, the imaging direction b1 faces the outside of the curve more than the imaging direction a1. Then, when the center in the width direction of the lane is set as the target position, a distance a2 from the imaging direction a1 of the imaging device of the vehicle A to the target position after a predetermined time and a predetermined time after the imaging direction b1 of the imaging device of the vehicle B The distance b2 to the target position at is different, and as a result, the target position calculated by the target position calculation unit 52 is different between the vehicle A and the vehicle B.

  On the other hand, since the vehicle speed and the yaw rate do not change even if the turning angle of the vehicle is different, the estimated position calculated by the estimated position calculating unit 53 of the vehicle A and the estimated position calculated by the estimated position calculating unit 53 of the vehicle B are the same. Become.

  Therefore, as shown in FIG. 4, the amount of deviation ε between the target position calculated by the target position calculation unit 52 and the estimated position calculated by the estimated position calculation unit 53 varies depending on the vehicle type (particularly the wheel base). .

  Therefore, the correction unit 54 sets a correction coefficient for the target position in accordance with the vehicle type so that the deviation amount ε is constant regardless of the vehicle type. This correction coefficient can be obtained in advance by experiments or the like. Then, the correction unit 54 corrects the target position calculated by the target position calculation unit 52 with the correction coefficient set in this way.

  The steering control unit 55 has a function of performing steering control of the vehicle based on a deviation amount (difference) between the target position and the estimated position. That is, the steering control unit 55 performs steering control of the vehicle based on the amount of deviation between the target position corrected by the correction unit 54 and the estimated position calculated by the estimated position calculation unit 53.

  FIG. 5 is a diagram illustrating a control logic for performing steering control of the vehicle. As shown in FIG. 5, the steering control unit 55 includes a PI control unit 56 that performs PI (Proportional Integral) control, and a drive command unit 57 that performs rotation drive control of the rotation drive device 24 of the steering system 2. Yes.

  The PI control unit 56 includes a P term 56a that performs proportional control (P control) and an I term 56b that performs integral control (I control). The PI control unit 56 calculates a target steering angle that is a target steering angle by PI control based on the amount of deviation between the target position and the estimated position, and when the amount of deviation is equal to or greater than a predetermined threshold, the drive command unit A command for rotating the rotation drive device 24 is output from 57. As the PI control unit 56, a known control device that performs PI control can be used.

  Here, the rotation drive control of the rotation drive device 24 includes a case where a rotation angle is commanded and a torque is commanded. In either case, a command is output when the amount of deviation is equal to or greater than a predetermined threshold value. However, when the rotation angle is commanded, the threshold value can be made smaller than when torque is commanded. For example, when commanding the rotation angle, the threshold value of the deviation amount is ± 100 mm, and when commanding the torque, the threshold value of the deviation amount is ± 200 mm.

  When a command is output from the drive command unit 57 to the rotational drive device 24, the rotational drive device 24 is rotationally driven to rotate the steering shaft 22 and perform automatic steering. The estimated position calculation unit 53 performs τ seconds. A later estimated position is calculated.

  Next, the processing operation of the steering control device 1 will be described with reference to FIG. FIG. 6 is a flowchart showing the processing operation of the steering control device.

  The processing operation of the steering control device 1 shown in FIG. 6 is started when the automatic steering necessity determination unit 51 determines that the vehicle steering control is performed, and until an end condition for ending the vehicle steering control is satisfied. Is repeated at predetermined time intervals. Examples of the case where the end condition is satisfied include a case where the automatic steering necessity determination unit 51 determines to end the steering control of the vehicle, and a case where the engine switch of the vehicle is turned off.

  As shown in FIG. 6, in the steering control device 1, first, the lane information acquisition unit 3 acquires lane information ahead of the traveling direction of the vehicle (step S <b> 1), and the motion information acquisition unit 4 acquires the motion information of the vehicle. Is acquired (step S2). Note that either step S1 or step S2 may be processed first or in parallel.

  Next, the target position calculation unit 52 of the control unit 5 calculates the target position of the future vehicle based on the lane information acquired in step S1 (step S3), and the estimated position calculation unit 53 of the control unit 5 An estimated position of the future vehicle is calculated based on the vehicle motion information acquired in step S2 (step S4).

  Next, the correction unit 54 of the control unit 5 corrects the target position calculated in step S3 (step S5). In step S5, the target position calculated in step S3 is corrected by a target position correction coefficient corresponding to the vehicle type.

  Next, the steering control unit 55 of the control unit 5 calculates a deviation amount between the target position corrected in step S5 and the estimated position calculated in step S4, and calculates a target steering angle by PI control based on the deviation amount. (Step S6).

  Next, the steering control unit 55 of the control unit 5 determines whether or not the deviation amount calculated in step S6 is greater than or equal to a predetermined threshold (step S7).

  When it is determined that the amount of deviation is greater than or equal to the predetermined threshold (step S7: YES), the steering control unit 55 drives the rotation drive device 24 to rotate (step S8). Then, the processing operation of the steering control device 1 is once terminated and repeated from step S1 again.

  On the other hand, when it is determined that the amount of deviation is less than the predetermined threshold (step S7: NO), the steering control unit 55 temporarily ends the processing operation of the steering control device 1 without driving the rotational drive device 24 to rotate, Repeat from step S1 again.

  As described above, according to the present embodiment, the steering control unit 55 performs the steering control based on the difference between the target position and the estimated position, but the target position can be corrected by the correction unit 54. Thereby, even if the target position differs depending on the vehicle type, the target position can be corrected according to the vehicle type, so that the same position can be traveled even in vehicles of different vehicle types. In addition, since the target position is corrected by the correction unit 54, even if a general steering control logic is used as the portion α in FIG. 5, the same position can be caused to travel on vehicles of different vehicle types.

  In addition, since the target position varies depending on the wheel base of the vehicle, the correction accuracy of the target position can be improved by correcting the target position according to the wheel base of the vehicle.

  Further, since the estimated position can be calculated based on the speed and the yaw rate, the estimated position can be appropriately calculated by acquiring the speed and the yaw rate as the vehicle motion information.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, the specific configurations of the lane information acquisition unit and the exercise information acquisition unit have been described. However, the lane information acquisition unit and the exercise information acquisition unit may have any configuration as long as they can acquire the lane information and the exercise information, respectively. May be.

  In the above embodiment, the specific control mode of the steering control unit has been described. However, the steering control unit may be any control mode as long as the vehicle can perform steering control based on the difference between the target position and the estimated position. May be.

  In the above embodiment, the description has been made assuming that all functions are realized by one control device. However, these functions may be realized by a plurality of control devices, and one function is realized by a plurality of control devices. May be.

  In the above embodiment, the processing operation of the steering control device has been specifically described. However, the processing order of each step can be changed as appropriate, and for example, the processing order of each step may be changed as appropriate. These steps may be performed in parallel.

  DESCRIPTION OF SYMBOLS 1 ... Steering control apparatus, 2 ... Steering system, 21 ... Gear box, 22 ... Steering shaft, 23 ... Steering wheel, 24 ... Rotation drive device, 3 ... Lane information acquisition part, 4 ... Movement information acquisition part, 5 ... Control part 51 ... Automatic steering necessity determination unit, 52 ... Target position calculation unit, 53 ... Estimated position calculation unit, 54 ... Correction unit, 55 ... Steering control unit, 56 ... PI control unit, 56a ... P term, 56b ... I term 57 ... Drive command section, A ... vehicle, B ... vehicle.

Claims (8)

A steering control device that performs steering control of a vehicle,
A lane information acquisition unit mounted on the vehicle for acquiring lane information ahead of the vehicle in the traveling direction;
An exercise information acquisition unit for acquiring exercise information of the vehicle;
A target position calculation unit that calculates a future target position of the vehicle based on the lane information acquired by the lane information acquisition unit;
An estimated position calculation unit that calculates an estimated position of the vehicle in the future based on the current movement information of the vehicle acquired by the movement information acquisition unit;
A correction unit that corrects the target position calculated by the target position calculation unit;
A steering control unit that performs steering control of the vehicle based on a difference between the target position and the estimated position;
Equipped with a,
The correction unit corrects the target position calculated by the target position calculation unit so that the difference between the target position and the estimated position becomes smaller as the wheelbase of the vehicle becomes longer.
Steering control device. The motion information acquisition unit acquires speed and yaw rate as vehicle motion information.
The steering control device according to claim 1 . The correction unit corrects the target position calculated by the target position calculation unit so as to travel in the same position even in vehicles of different vehicle types.
The steering control device according to claim 1 or 2 . The correction unit calculates the target position so that a deviation amount between the target position calculated by the target position calculation unit and the estimated position calculated by the estimated position calculation unit is constant regardless of a vehicle type. Correcting the target position calculated by the unit,
The steering control device according to any one of claims 1 to 3 . The lane information acquisition unit acquires the lane information from image data captured by an imaging device.
The steering control device according to any one of claims 1 to 4 . The steering control unit performs steering control of the vehicle based on the difference between the target position and the estimated position only when the difference between the target position and the estimated position is greater than or equal to a threshold value.
The steering control device according to any one of claims 1 to 5 . An automatic steering necessity determination unit that determines whether to perform steering control of the vehicle;
The automatic steering necessity determination unit performs steering control of the vehicle when the driver cannot drive.
The steering control device according to any one of claims 1 to 6 . The automatic steering necessity determination unit drives the driver based on an operation of an emergency button installed in the vehicle or based on an analysis result of a driver's face image captured by a camera installed in a vehicle interior. To determine if it is not possible,
The steering control device according to claim 7 .

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