JP2005332192A - Steering support system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering support system capable of accurately performing steering support. <P>SOLUTION: The steering support system sets up a running target point, determines a target running track so as to pass through the running target point, and performs the steering support so that an actual yaw rate is coincided with a target yaw rate when a vehicle runs on the target running track. When a preceding vehicle is in the distance, running road observation points are set up from running road information because the running road is clearly seen. When the preceding vehicle is near, the position of the preceding vehicle is set up as preceding vehicle observation points because there are lots of unseen zones on the running road. Based on selected observation points, the target running track can be set up. Further, observation points can be set up as the target points to be scheduled to run, and the target running track can be set up for passing through the target points as well as minor compensation on the target points. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steering assist system.

  Conventional steering assist systems are described in Patent Literature 1 and Patent Literature 2 below. In these patent documents, a travel target point is set, a target travel locus is determined so as to pass over the travel target point, and the actual yaw rate matches the target yaw rate when the vehicle travels on the target travel locus. Steering control is performed.

JP-A-2-27688

JP-A-5-197423

  However, in the conventional steering assist system, when the travel path information is obtained from the output of the video camera and the travel target point is set on the travel path, the forward travel information is displayed when the preceding vehicle is very close. There is a problem that image processing cannot be performed because the image cannot be acquired, and therefore accurate steering assistance cannot be performed.

  The present invention has been made in view of such a problem, and an object thereof is to provide a steering support system capable of performing accurate steering support.

  In order to solve the above-described problem, the steering support system according to claim 1 detects the position of a preceding vehicle positioned in front of the host vehicle in the steering support system that steers the host vehicle along the target travel locus. The vehicle position detection means, the preceding vehicle gazing point setting means for setting the position of the preceding vehicle as the preceding vehicle gazing point, and the distance from the own vehicle to the predetermined traveling path gazing point is the distance from the own vehicle to the preceding vehicle gazing point. A gazing point selecting means characterized in that a target driving locus is set based on the driving path gazing point when the driving angle is smaller than the gazing point, and a target driving locus is set based on the preceding vehicle gazing point when it is larger. Features.

  In this case, if the preceding vehicle is sufficiently far away, the road will not be blocked, so the road gaze point obtained from the road information will be used. Because there are many, the target vehicle locus is set based on the selected vehicle gazing point using the vehicle gazing point for the preceding vehicle. Note that the gazing point can be set as a target point to be traveled by the vehicle, and a target travel locus passing through the target point can be set.

  Further, the steering assist system according to claim 2 includes an imaging unit that captures an image of the traveling road, and a traveling road gazing point setting unit that sets a traveling road gazing point on the traveling road from an image of the traveling road photographed by the imaging unit. Is further provided. That is, if a travel route is imaged by the imaging means, a travel route gazing point can be set on the travel route by image processing.

  The steering assist system according to claim 3 calculates a turning radius of the preceding vehicle from a temporal change of the preceding vehicle gazing point, and sets a target traveling locus passing through the preceding vehicle gazing point along the turning radius. It further comprises a target travel locus setting means for following the vehicle.

  The preceding vehicle gazing point that changes with time can be approximated on a certain circle. That is, the radius that satisfies this circle equation is the approximate turning radius of the travel path. The target travel locus can pass through the preceding vehicle gazing point along the turning radius. In this case, when the host vehicle passes through the target travel locus, the target vehicle will follow the preceding vehicle.

  According to the steering assist system of the present invention, it is possible to recognize the traveling path according to the approaching preceding vehicle and to perform accurate and accurate steering support.

  Hereinafter, the driving support system according to the embodiment will be described. The same reference numerals are used for the same elements, and duplicate descriptions are omitted.

  FIG. 1 is a block diagram of the driving support system.

  The vehicle body BDY is provided with wheels W, and the front wheels of the wheels W are steered by the steering device 1. The wheel W is driven by the power engine 2, and the rotation speed is detected by the wheel speed sensor 3. The rotation of the wheel W is braked by the braking device 4. This vehicle is equipped with an imaging device 5 such as a video camera, and images the road ahead of the vehicle. Further, the vehicle is equipped with a radar 6 such as a millimeter wave radar, and detects the position and relative velocity of the object from the reflected wave from the object in front of the vehicle.

The output of the imaging device 5 is input to the image processing device 7, which performs edge processing (approximate curve processing) on the white line (lane) of the traveling road, and turns the curvature of the white line on the image into the actual traveling road. Convert to radius R _(load) and output. That is, the input image to the imaging device 5 is an image obtained by projecting a white line drawn in the horizontal direction onto the imaging surface of the image processing device 7 extending in the vertical direction. Therefore, the obtained vertical image is inverted on the horizontal plane. Calculate the equation of the circle that satisfies the position of at least three points in the arc of the white line that is formed by projective transformation and reverse transformation, and if there are two white lines, take the average of the radii of both circles and calculate this average The radius is the turning radius R _{(load) of the} travel path. If a white line on the road cannot be detected, the road shoulder may be regarded as a white line by edge processing.

  That is, the imaging device 5 captures the travel road, but the image processing device 7 together with the control device 9 sets a travel route gazing point, which will be described later, on the travel road from the image of the travel path captured by the imaging device 5. It also functions as a gaze point setting means. If the travel route is photographed by the imaging device 5, the travel route gazing point can be set on the travel route by image processing.

  This vehicle is equipped with a yaw rate sensor 8 and outputs the yaw rate γ of the vehicle. Further, the steering angle sensor 10 outputs the steering angle θ of the front wheels.

The control device 9 includes at least the output of the wheel speed sensor 3 (vehicle speed Vs), the output of the radar 6 (preceding vehicle position, relative distance: L, relative speed, etc.), the output of the image processing device 7 (R _(load) ), The output of the yaw rate sensor 8 (yaw rate γ) and the output of the steering angle sensor 10 (steering angle θ) are input. The control device 9 outputs a control signal E for the power engine 2, a control signal B for the braking device 4, and a control signal for the steering device 1 based on the input data.

  FIG. 2 is a flowchart of control in the control device 9.

When the steering assist mode is executed, first, the _gaze point distance P _αn and the turning radius R _n are calculated (S1), and then parameters for controlling the vehicle so that the actual parameters match these calculated values. Is calculated (S2). The parameters for controlling the vehicle include, in addition to the steering angle θ, the power rotational speed included in the control signal E to the power engine 2 and the braking force included in the control signal B to the braking device 4.

That is, in step S2, a target point to the fixation point P _.alpha.n, sets a target travel trajectory of the turning radius R _n therethrough, obtains a target yaw rate gamma _t when the target running locus vehicle travels at a speed Vs , if the actual yaw rate gamma is smaller than the target yaw rate gamma _t is basically to control the steering apparatus 1 as the steering angle θ increases, the greater the steering as the steering angle θ is reduced The apparatus 1 is controlled. In such control, the travel route of the vehicle traveling along the target travel locus may be controlled by controlling the power rotational speed and the braking force. Note that the target yaw rate γ _t in the case of the speed V _s and the turning radius R _n can be uniquely determined as long as it is a simple expression. As a result, the vehicle travels along the target travel locus.

  If it is in the steering assist control execution mode, the process returns to step S1 to continue the calculation, and if not, the control is terminated (S3).

  Next, a subroutine for executing step S1 will be described.

  FIG. 3 is a flowchart of subroutine control in the control device 9. It is assumed that the count number of data sampling is n, and n = 0, 1, 2, 3, 4...

  FIG. 4 is a diagram for explaining the traveling locus of the vehicle. The position of the host vehicle s is the origin On, the front of the host vehicle s is the y axis, and the width direction is the x axis.

In the subroutine control, first, n + 1 is substituted for the data sampling count number n (initial value n = 0) (S11), and the detection data is read (S12). The radar output L as detection data has a preceding vehicle position (Ax _n , Ay _n ), a relative speed (ΔV _n ) from the own vehicle s to the preceding vehicle b, and the wheel speed sensor output Vs is the own vehicle speed Vs _n , A traveling path turning radius R _{n (load)} which is an output of the image processing device 7 is provided.

  Next, it is determined whether or not the count number is 2 or more (S13). If n is 1, in order to obtain a differential value in a subsequent step, the process returns to step S11 and n + 1 is substituted for n, and the detection is performed again. Data is read (S12). If n is 2 or more, the process proceeds to the next step.

In the next step, the turning radius Rn _(vehicle) of the preceding vehicle is calculated (S14). In addition to the data of n = 1, when the data of n = 2, which is a sampling timing later in time, is obtained, the turning radius R _{n (vehicle)} of the preceding vehicle base is calculated. When the speed of the preceding vehicle is V _n , the timing of data sampling is dt, and the angle of the preceding vehicle displaced during this period dt is θ _n , the turning radius R _{n (vehicle)} is given by the following equation.

Turning radius R _{n (vehicle)} = V _n · dt / θ _n

It should be noted that the speed of the preceding vehicle V n = the vehicle speed Vs n + the relative speed ΔV n . Angle theta n is the sampling time of the velocity vector of V n-1 of n-1 V n-1 *, when the velocity vector of V n at the sampling time n and V n *, is given by the following equation. Note that these vectors can be obtained from a minute period differential value at each position if the relative speed and position of the preceding vehicle are known.

Angle θ _n = cos ⁻¹ (V _n−1 ^* × V _n ^* ) / (| V _n−1 ^* || V _n ^* |)

That is, the steering assist system calculates a turning radius R _{n (vehicle)} of the preceding vehicle from the temporal change of the preceding vehicle gazing point An, and passes through the preceding vehicle gazing point An along the turning radius R _{n (vehicle).} A target travel locus is set, and a target travel locus setting means for following the preceding vehicle is provided. The preceding vehicle gazing point An that changes with time (which becomes a speed vector in a minute period) can be placed on a certain circle. That is, the radius that satisfies this circle equation is the turning radius of the preceding vehicle. The target travel locus can pass through the preceding vehicle gazing point along the turning radius. In this case, when the host vehicle passes through the target travel locus, the target vehicle will follow the preceding vehicle.

Incidentally, the center of rotation that gives the turning radius R _{n (vehicle)} is indicated by AOn in FIG.

Next, the travel path gazing point distance L _αn is read (S15). The travel path gazing point distance L _αn is a value determined by the steering assist control logic, and as a simple example, is given by L _αn = A + B × Vs _n where A and B are constants. For example, the traveling road gazing point distance L _αn can be set to 50 m if the _host vehicle speed Vs is 50 km / h. A position α (d _αn , L _αn ) that is separated from the _host vehicle s by the travel path gazing point distance L _αn along the turning radius R _{n (load)} based on the travel path image is set as the travel path gazing point. The position An (Ax _n , Ay _n ) of the preceding vehicle b is set as the preceding vehicle gazing point.

Next, the traveling path gazing point distance L _αn and the preceding vehicle gazing point distance Ay _n are compared (S16). If L _αn > Ay _n , the preceding vehicle b is close, so that the preceding vehicle follows the movement of the preceding vehicle. performs vehicle following mode control (S17), in the case of L αn ≦ Ay _n, in accordance with the travel path detection information, the travel path following mode control (S18).

In the preceding vehicle follow-up mode control, the gazing point distance P _αn is set as the preceding vehicle gazing point distance Ay _n , and the turning radius R _n is a turning radius R _{n (vehicle)} based on the preceding vehicle.

In the traveling path follow-up mode control, the gazing point distance P _αn is set as the traveling path gazing point distance L _αn , and the turning radius R _n is a turning radius R _{n (load)} based on the traveling path.

In this way, the turning radius R _n selected according to the _gazing point distance P _αn is output (S19).

As described above, in step S2, a target point to the fixation point P _.alpha.n, sets a target travel trajectory of the turning radius R _n therethrough, target yaw rate γ when the target running locus vehicle travels at a speed Vs _When the actual yaw rate γ is smaller than the target yaw rate γ _t , the steering device 1 is controlled so that the steering angle θ (or torque) increases, and when it is larger, the steering angle θ decreases. The steering device 1 is controlled.

That is, the steering assist system described above detects the position An (Ax _n , Ay _n ) of the preceding vehicle b located in front of the host vehicle s in the steering support system that steers the host vehicle s along the target travel locus. Radar (vehicle position detecting means) 6, leading vehicle gazing point setting means (step S 12) for setting the position of the preceding vehicle b as the preceding vehicle gazing point An, and a distance from the host vehicle s to a predetermined traveling path gazing point α. When the distance L _αn is smaller than the distance Ay _n from the host vehicle s to the preceding vehicle gazing point An, a target traveling locus is set based on the traveling path gazing point An (turning radius R _{n (load)} and vehicle speed Vs _). determine a target yaw rate γ from _n), obtains a target yaw rate γ to set a target travel trajectory based on the preceding vehicle fixation point (the turning radius R _{n (vehicle)} from the vehicle speed Vs _n is greater) that And a fixation point selecting means, wherein (step S16 to S19).

  FIG. 5 is a diagram for explaining steering assistance.

The own vehicle s is provided with an imaging device 5, and an image within a certain angle of view directed forward can be obtained. When the preceding vehicle b exists and the preceding vehicle a does not exist, the preceding vehicle b is far away, so that the traveling road ROAD can be accurately imaged by the imaging device 5. A target gaze point P _αn is assumed.

  6, 7 and 8 show examples of images taken from the imaging device 5 of the host vehicle s.

As shown in FIG. 5, when the preceding vehicle a is close to the host vehicle s, there are many areas in which the travel road (white line WT) cannot be completely photographed due to the various travel road shapes shown in FIGS. 6 to 8. Become. The travel locus may be set at the center in the width direction of the parallel white lines, but it is difficult to calculate the turning radius R _{n (load)} based on the travel path within the range that can be acquired by the camera.

As described above, when the preceding vehicle “a” exists nearby, the traveling road ROAD has many areas that cannot be accurately imaged by the imaging device 5. In this case, the preceding vehicle position a is set as the preceding vehicle gazing point (An). Based on any selected gazing point P _αn (α or An), a turning radius R _{n (} load ₎ or R _{n (vehicle)} is selected to set a target travel locus.

  Note that the gazing point can be set as a target point to be traveled by the vehicle, and a target travel locus passing through the target point can be set.

  In the above steering assistance system, it is also possible to detect the movement of the following vehicle and obtain travel path information ahead of the preceding vehicle from the turning radius estimated based on the information. Even if the preceding white line is approaching and the front white line is hidden behind the vehicle and cannot be detected, the target travel locus can be set based on the turning radius of the preceding vehicle and is more accurate than the path shape estimated from the range where the white line can be detected. The road shape ahead of the preceding vehicle (the preceding vehicle traveling route) can be estimated well.

  If the gazing distance in front of the steering assist is farther than the inter-vehicle distance to the preceding vehicle, the gazing distance is the distance to the preceding vehicle, and the road information such as the turning radius of the road is used as control information. Thus, even when the front white line is hidden behind the preceding vehicle and cannot be detected, the steering assist control along the actual travel path can be performed. If the forward gazing distance at the time of steering support is closer than the inter-vehicle distance to the preceding vehicle, by using the road information such as the curvature radius calculated from the white line information obtained by image processing etc. as control information, Even when the white line can be detected only in a fragmentary manner due to the influence of the preceding vehicle, accurate curve information can be obtained, thereby enabling steering assistance suited to the actual traveling rod.

  By calculating the turning radius of the preceding vehicle from the time change of the movement vector of the following vehicle, it is possible to perform calculations after taking into account the direction of travel of the vehicle (including tire slip angle). A value approximated to can be calculated. Further, by always setting the front gazing point distance as the preceding vehicle position, it is possible to perform the steering control while following the preceding vehicle without detecting the white line. In this case, it can also be used for fail-safe handling when the white line cannot be detected suddenly due to environmental changes.

  The present invention can be used in a steering assist system.

It is a block diagram of a driving support system. 5 is a flowchart of control in the control device 9. 7 is a flowchart of subroutine control in the control device 9; It is a figure for explaining a run locus. It is a figure for demonstrating steering assistance. The image image | photographed from the imaging device 5 of the own vehicle s is shown. The image image | photographed from the imaging device 5 of the own vehicle s is shown. The image image | photographed from the imaging device 5 of the own vehicle s is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Power engine, 3 ... Wheel speed sensor, 4 ... Braking device, 5 ... Imaging device, 6 ... Radar, 7 ... Image processing device, DESCRIPTION OF SYMBOLS 8 ... Yaw rate sensor, 9 ... Control apparatus, 10 ... Steering angle sensor, a ... A preceding vehicle, BDY ... Vehicle body, ROAD ... Running road, s ... Own vehicle, W ... wheels, WT ... white lines.

Claims (3)

In a steering support system that steers the vehicle along a target travel locus,
Vehicle position detection means for detecting the position of a preceding vehicle located in front of the host vehicle;
Preceding vehicle gazing point setting means for setting the position of the preceding vehicle as a preceding vehicle gazing point;
When the distance from the host vehicle to a predetermined traveling path gazing point is smaller than the distance from the host vehicle to the preceding vehicle gazing point, a target traveling locus is set based on the traveling path gazing point. , A gazing point selection means for setting a target travel locus based on the preceding vehicle gazing point,
A steering assist system comprising: Imaging means for photographing the travel path;
A traveling road gazing point setting means for setting the traveling road gazing point on a traveling road from an image of the traveling road photographed by the imaging means;
The steering assist system according to claim 1, further comprising: A target travel locus setting means for following the preceding vehicle that calculates a turning radius of the preceding vehicle from the temporal change of the preceding vehicle gazing point and sets a target traveling locus that passes through the preceding vehicle gazing point along the turning radius; The steering support system according to claim 1 or 2, further comprising:

Images