JP5379614B2 - Vehicle steering assist control device - Google Patents

Description

  The present invention relates to a steering assist control device for a vehicle that assists steering so as to travel on a set optimum traveling path.

  In recent years, various technologies for improving safety and comfort have been developed and put into practical use in vehicles.

  For example, in Japanese Patent Application Laid-Open No. 2006-264624, the assist torque is set so that the magnitude is changed by changing the map according to the driver's attention reduction degree, and the waveform and / or frequency does not affect the vehicle motion. A technique for outputting a lane keeping assist device is disclosed.

JP 2006-264624 A

  However, in the control that outputs the assist torque with a waveform and / or frequency that does not affect the vehicle motion as in the above-mentioned Patent Document 1, an alarm is given according to the degree of the driver's attention reduction. Is not properly transmitted to the driver, there is a problem that it is difficult for the vehicle to properly maintain the lane. Moreover, even if the warning is transmitted to the driver, there is a problem that it is not possible to appropriately cope with the case where the vehicle cannot maintain lane driving due to the steering of the driver. Therefore, it is conceivable that the steering control is automatically performed along the set target traveling path. However, the steering is performed by the driver to the last, and the steering control cannot be appropriately involved in the steering by the driver. In contrast, there is a risk that the control may be inconvenient for the driver.

  The present invention has been made in view of the above circumstances, and provides a steering assist control device for a vehicle that supports steering while guiding a driver so as to maintain a traveling path while appropriately participating in the driver according to a driver state. It is intended to provide.

The present invention includes a forward information detecting means for detecting traveling road information ahead of the host vehicle, a driving state detecting means for detecting a driving state of the own vehicle, and a target progress of the own vehicle based on the traveling path information ahead of the own vehicle. Target traveling path setting means for setting a road, estimated traveling path setting means for setting an estimated traveling path that the host vehicle is predicted to travel based on the current driving state of the host vehicle, and a state in which the driver has released the steering wheel The control gain can be varied according to either the hand-off state or the driver's driving consciousness reduction degree, the driver's driving consciousness degree detecting means for detecting the driver's driving consciousness reduction degree, or the driver's driving consciousness reduction degree detecting means. Based on the control gain setting means to be set, the driving state of the host vehicle, the target traveling path, the estimated traveling path, and the control gain, an operation for the host vehicle to travel on the target traveling path is performed. A steering control amount calculating means for calculating a control amount, and a steering means for steering based on the steering control amount, the control gain setting means, when detecting the hands-off state, a long time of the hand-release state As described above, the control gain is set in a direction in which the settling time until the own vehicle converges on the target travel path is shortened .

  According to the steering assist control device for a vehicle according to the present invention, it is possible to control and assist steering while guiding the driver so as to maintain the traveling path while appropriately participating in the driver according to the driver state.

1 is a configuration explanatory diagram of a vehicle steering system according to an embodiment of the present invention. FIG. It is a functional block diagram of the steering control part which concerns on one Embodiment of this invention. It is a flowchart of the steering assistance control program which concerns on one Embodiment of this invention. It is explanatory drawing of the target traveling path, estimated traveling path, and front gaze distance which concerns on one Embodiment of this invention. It is explanatory drawing of the map of the control gain set according to the arousal level according to one Embodiment of this invention, a muzziness level, and hand-off time. It is explanatory drawing of the settling time defined by the control gain which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an electric power steering apparatus. In the electric power steering apparatus 1, a steering shaft 2 is rotatably supported on a vehicle body frame (not shown) via a steering column 3, and one end thereof is It extends to the driver's seat side, and the other end extends to the engine room side. A steering wheel 4 is fixed to an end portion of the steering shaft 2 on the driver's seat side, and a pinion shaft 5 is connected to an end portion extending to the engine room side.

  A steering gear box 6 extending in the vehicle width direction is disposed in the engine room, and a rack shaft 7 is inserted into and supported by the steering gear box 6 so as to be reciprocally movable. A rack (not shown) formed on the rack shaft 7 is engaged with a pinion formed on the pinion shaft 5 to form a rack and pinion type steering gear mechanism. The left and right ends of the rack shaft 7 protrude from the end of the steering gear box 6, and a front knuckle 9 is connected to the end via a tie rod 8. The front knuckle 9 rotatably supports left and right wheels 10L and 10R as steering wheels, and is supported by a vehicle body frame via a king pin (not shown) so as to be steerable. Accordingly, when the steering wheel 4 is operated and the steering shaft 2 and the pinion shaft 5 are rotated, the rack shaft 7 is moved in the left-right direction by the rotation of the pinion shaft 5, and the front knuckle 9 is moved to the king pin (not shown). ) And the left and right wheels 10L, 10R are steered in the left-right direction.

  An electric motor 13 is connected to the pinion shaft 5 via an assist transmission mechanism 11, and the electric motor 13 assists the steering torque applied to the steering wheel 4. The electric motor 13 is driven via the motor drive unit 21 so as to have a steering torque (control amount) Tc set by a steering control unit 20 described later. In the present embodiment, the motor drive unit 21 and the electric motor 13 constitute a steering means.

  The steering control unit 20 includes a vehicle speed sensor 31 that detects the vehicle speed V of the vehicle, a yaw rate sensor 32 that detects the yaw rate γ, a road shape ahead, and a front information detection unit that detects the yaw angle θca with respect to the traveling path of the host vehicle. Forward recognition device 33, release state detection device 34 as a release state detection means for detecting the release state of the driver, awakening as a driving awareness reduction degree detection means for detecting a driver's arousal level DA as a driver's driving awareness reduction degree A degree detection device 35 is connected to a degree-of-driving degree detection device 36 as a degree of driving awareness reduction degree detecting means for detecting the degree of driver's degree of depression DL as the degree of reduction in driving awareness of the driver.

  The forward recognition device 33 extracts, for example, white lines and curbs from image information captured by a stereo camera (CCD camera) disposed in the vehicle interior facing forward, and the traveling path ahead of the host vehicle is shown in FIG. Such an XZ coordinate plane (the coordinate plane having the width direction of the host vehicle as the X axis and the front and rear direction as the Z axis) is detected. In addition, the inclination with respect to the travel path at the current position of the host vehicle (the origin on the XZ coordinate plane) is calculated as the yaw angle θca and output to the steering control unit 20. For example, a central portion is calculated as a target travel path from the front travel path, this target travel path is approximated by a quadratic curve, and a value obtained by differentiating the approximate expression of the approximate target travel path at Z = 0 ( (Slope with respect to Z axis).

  For example, the hand-off state detection device 34 determines that the hand is released when the value from a steering torque sensor (not shown) is substantially zero.

  The arousal level detection device 35 detects the degree of decrease in driver's driving consciousness as a gradual level of wakefulness DA (three stages are exemplified in the present embodiment). It indicates that the degree of driving awareness is low, and conversely, the lower the alertness DA, the higher the degree of driving awareness of the driver. As a technique for detecting the awakening level DA, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 2005-71185 is employed. In this technique, the amount of high frequency component obtained by frequency-converting the amount of displacement of the vehicle in the vehicle width direction detected in time series and the yield are calculated from the ratio of the component amount to the estimated value of arousal level. ing. Moreover, the technique disclosed by Unexamined-Japanese-Patent No. 2007-312905 can also be employ | adopted as another detection technique of the arousal level DA. In this technique, the arousal level is detected from the pattern of movement of the heel.

  The illusion degree detection device 36 detects the degree of decrease in driver's driving consciousness as a gradual degree degree DL (three examples are exemplified in the present embodiment). It shows that the degree of decrease in driving awareness is high, and conversely, the lower the mean DL is, the lower the degree of reduction in driving awareness of the driver is. For example, a technique disclosed in Japanese Patent Application Laid-Open No. 8-178712 is employed as the technique for detecting the degree of complexity DL. In this technique, the degree of ambiguity is detected on the basis of the stop time of the driver's line of sight and the number of confirmations within a predetermined time of the rearview mirror and side mirror.

  The steering control unit 20 calculates the X coordinate xc of the target passing point Pc at the forward gazing distance zt based on the traveling path information ahead of the host vehicle based on each input signal described above, and the estimated passing point at the forward gazing distance zt. An X coordinate xe of Pe is calculated based on the current driving state of the host vehicle, a calculation term obtained by multiplying the deviation of these coordinates xc and xe by the first control gain Gl, and the yaw angle θca and the second control gain. The steering torque (control amount) Tc is calculated by adding the calculation term multiplied by Gy and output to the motor drive unit 21. Here, the first and second control gains Gl and Gy described above are directions in which the settling time of the steering control in which the host vehicle travels on the target travel path is shorter as the continuous time (hand-off time) Tso in the hand-off state is longer. (Gl and Gy are respectively large values) On the other hand, when the hand-off state is not detected, the steering in which the host vehicle travels on the target traveling path, as the awakening level DA is lower or the indiscriminate degree DL is higher. The control settling time is set to be shorter (Gl and Gy are larger values).

  That is, as shown in FIG. 2, the steering control unit 20 mainly includes a forward gaze distance calculation unit 20a, a target passage point calculation unit 20b, an estimated passage point calculation unit 20c, a control gain setting unit 20d, and a control amount calculation unit 20e. It is configured.

  The forward gaze distance calculation unit 20 a receives the vehicle speed V from the vehicle speed sensor 31. Then, for example, the forward gaze distance zt is calculated based on a preset forward gaze time (for example, 1.2 seconds), and is output to the target passing point calculation unit 20b and the estimated passing point calculation unit 20c. . Note that the forward gaze distance zt is not limited to this example, but may be set from a map corresponding to the vehicle speed V set in advance through experiments or the like.

  The target passing point calculation unit 20b receives the forward travel path information from the front recognition device 34, and receives the front gaze distance zt from the front gaze distance calculation unit 20a. Then, for example, as shown in FIG. 4, the center portion of the front travel path is set as the target travel path, and the center portion of the left end and the right end of the front travel path at the front gaze distance zt is set as the target passing point Pc. The X coordinate xc of the target passing point Pc is calculated. The X coordinate xc of the target passing point Pc is output to the target handle angle calculation unit 20d. Thus, the target passing point calculation unit 20b is provided as target traveling path setting means.

The estimated passing point calculation unit 20c receives the vehicle speed V from the vehicle speed sensor 31, the yaw rate γ from the yaw rate sensor 33, and the front gaze distance zt from the front gaze distance calculation unit 20a. And, for example, according to the following equation (1), the passing point at the forward gaze distance zt of the estimated traveling path predicted to travel by the host vehicle based on the current driving state of the host vehicle is set as the estimated passing point Pe. The X coordinate xe of the estimated passing point Pe is calculated and output to the target handle angle calculation unit 20d. Thus, the estimated passing point calculation unit 20c is provided as estimated traveling path setting means.
xe = (zt ² · γ) / (2 · V) (1)

Note that the X coordinate xe of the estimated passing point Pe may be obtained by the following equation (2) based on the handle angle θH.
xe = (θH · zt ² ) / (2 · (1 + A · V ² ) · lw · n) (2)
Here, lw is a wheel base, and n is a steering gear ratio. A is a stability factor of the vehicle, and is calculated by the following equation (3), for example.
A = − (m / (2 · (lf + lr) ² ))
(Lf · Kf−lr · Kr) / (Kf · Kr) (3)
Here, m is the vehicle mass, lf is the distance between the front axle and the center of gravity, lr is the distance between the rear axle and the center of gravity, Kf is the equivalent cornering power of the front wheels, and Kr is the equivalent cornering power of the rear wheels.

  The control gain setting unit 20 d receives the detection result of the released state from the released state detection device 34, receives the awakening level DA from the awakening level detection device 35, and receives the abusiveness level DL from the abusiveness level detection device 36. First, when it is determined that the hand-off state is detected with reference to the detection result of the hand-off state, the continuous time (hand-off time) Tso of the hand-off state is counted, and according to the hand-off time Tso, For example, referring to a control gain map as shown in FIG. 5A, the first control gain Gl and the second control gain Gy are set and output to the control amount calculation unit 20e. If the state is not let go, the degree of arousal DA and the degree of DL are compared, and the larger one (the one where the driver's driving consciousness state appears more clearly) is selected as the driver's driving consciousness. Then, with reference to the selected driving consciousness map (FIG. 5B), the first control gain Gl and the second control gain Gy are set and output to the control amount calculation unit 20e. That is, when the arousal level DA is larger than the illness level DL, the first control gain Gl and the second control gain Gy are set according to the map of the left side of FIG. On the other hand, when the degree DL is greater than the arousal level DA, the first control gain Gl and the second control gain Gy are set according to the map of the right side of FIG. It outputs to the quantity calculation part 20e. The meanings of the first control gain Gl and the second control gain Gy and the characteristics shown in FIGS. 5A and 5B will be described later. Thus, the control gain setting unit 20d is provided as control gain setting means.

The control amount calculation unit 20e receives the yaw angle θca from the forward recognition device 33, the X coordinate xc of the target passage point Pc from the target passage point calculation unit 20b, and the estimated passage point Pe from the estimated passage point calculation unit 20c. The X coordinate xe is input, and the first control gain Gl and the second control gain Gy are input from the control gain setting unit 20d. Then, the steering torque (control amount) Tc is calculated by the following equation (4) and output to the motor drive unit 21. As described above, the control amount calculation unit 20e is provided as a steering control amount calculation unit.
Tc = Gl · (xc−xe) + Gy · θca (4)

  As is apparent from the equation (4), the first control gain Gl is (multiplied) with respect to the deviation between the X coordinate xc of the target passing point Pc and the X coordinate xe of the estimated passing point Pe at the forward gaze distance zt. The calculation term “Gl · (xc−xe)” is a calculation term representing a control amount for controlling the lateral position of the vehicle in the traveling lane at the forward gaze distance zt.

  The second control gain Gy is a gain for (multiplying) the yaw angle θca, and the calculation term “Gy · θca” is a calculation that represents a control amount that maintains translation of the target traveling path of the vehicle. It is a term.

  Therefore, as shown in FIG. 6A, the larger the first and second control gains Gl and Gy are set to larger values, the larger the control amount Tc becomes, and the settling until the control value converges to the target value. The time is faster, and the settling time until convergence to the target value is earlier than the characteristic 2 in FIG. Similarly, as shown in the characteristic 3 in FIG. 6B, the settling time until convergence to the target traveling path is earlier than the characteristic 2 in FIG.

  That is, in the present embodiment, when the hand-off state is detected, the first and second control gains Gl, according to the map of FIG. 5A, according to the continuous time (hand-off time) Tso of the hand-off state, Gy is set, and as the hand release time Tso is longer, the first and second control gains Gl and Gy are set to larger values, and the steering control in which the host vehicle travels on the target travel path is set. Control is performed in a direction that shortens the time, and steering control is actively involved in order to maintain traveling along the traveling path, and appropriate steering control can be involved.

  Further, when the hand-off state is not detected, the first and second control gains Gl and Gy are determined according to the map of FIG. 5B according to the driver's driving consciousness (awakening level DA or ambiguity level DL). The first and second control gains Gl and Gy become larger values when the driving awareness of the driver is low (when the arousal level DA is low or when the ambiguity level DL is high). Set and controlled in a direction that shortens the settling time of the steering control in which the host vehicle travels on the target traveling path, and appropriate steering control is actively involved in order to maintain traveling along the traveling path. Can be involved. On the contrary, the first and second control gains Gl and Gy are set to a smaller value when the driver's driving consciousness is high (when the arousal level DA is high or when the maneuverability DL is low), and the own vehicle Is controlled in a direction in which the settling time of the steering control traveling on the target traveling path becomes longer, so that excessive interference with the driver's steering can be prevented.

Next, the steering assist control executed by the steering control unit 20 will be described with reference to the flowchart of FIG.
First, in step (hereinafter abbreviated as “S”) 101, necessary parameters, that is, the vehicle speed V, the yaw rate γ, the road shape ahead, the yaw angle θca with respect to the traveling path of the own vehicle, the detection result of the hand-off state, the arousal level DA, Mandom DL is read.

  Next, in S102, the forward gaze distance calculation unit 20a calculates the forward gaze distance zt according to the vehicle speed V and the like as described above.

  Next, proceeding to S103, the target passing point calculation unit 20b calculates the X coordinate xc of the target passing point based on the forward travel path information and the forward gaze distance zt.

  Next, the process proceeds to S104, and the estimated passing point calculation unit 20c calculates the X coordinate xe of the estimated passing point by the above-described equation (1) or (2).

  Hereinafter, the processes according to S105 to S110 are processes executed by the control gain setting unit 20d. First, in S105, it is determined whether or not the hand is released from the steering wheel.

  If the result of this determination is that the hand is released, the process proceeds to S106, the continuous time (hands-off time) Tso in the hand-off state is counted, the process proceeds to S107, and, for example, as shown in FIG. The first control gain Gl and the second control gain Gy are set with reference to the control gain map.

  On the other hand, if it is determined in step S105 that the state is not the hand-off state, the process proceeds to step S108, and the magnitude of the arousal level DA is compared with the level of the casualness DL. As a result of the comparison, if the arousal level DA is greater than or equal to DL, the process proceeds to S109, and the first control gain Gl and the second control are performed based on the awakening level map on the left side of the map shown in FIG. The gain Gy is set. Conversely, if the arousal level DA is smaller than the illness level DL, the process proceeds to S110, and the first control gain Gl and the second control gain Gy are based on the ambiguity level map on the right side of the map shown in FIG. And set.

  After the first control gain Gl and the second control gain Gy are set in any one of S107, S109, and S110, the process proceeds to S111, and the control amount calculation unit 20e performs steering using the above-described equation (4). Torque (control amount) Tc is calculated and output to the motor drive unit 21 to exit the program.

  Thus, according to the embodiment of the present invention, the X coordinate xc of the target passing point Pc at the forward gaze distance zt is calculated based on the traveling path information ahead of the host vehicle, and the estimated passing point Pe at the front gaze distance zt. X coordinate xe is calculated based on the current driving state of the host vehicle, a calculation term obtained by multiplying the deviation of these coordinates xc and xe by the first control gain Gl, and the yaw angle θca and the second control gain Gy. The steering torque (control amount) Tc is calculated by adding the operation term multiplied by and output to the motor drive unit 21. Here, the first and second control gains Gl and Gy described above are directions in which the settling time of the steering control in which the host vehicle travels on the target travel path is shorter as the continuous time (hand-off time) Tso in the hand-off state is longer. (Gl and Gy are respectively large values), and steering control is actively involved to maintain traveling along the traveling path, and appropriate steering control can be involved. On the other hand, when the let-off state is not detected, the direction in which the settling time of the steering control in which the host vehicle travels on the target traveling path becomes shorter (Gl, Gy, as the awakening level DA is lower or the muffled level DL is higher). Each of which is set to a large value) and is controlled in such a direction that the settling time of the steering control in which the vehicle travels along the target traveling path is shortened, and the steering control is actively involved in order to maintain traveling along the traveling path. Therefore, appropriate steering control can be involved. On the contrary, the first and second control gains Gl and Gy are set to a smaller value when the driver's driving consciousness is high (when the arousal level DA is high or when the maneuverability DL is low), and the own vehicle Is controlled in a direction in which the settling time of the steering control traveling on the target traveling path becomes longer, so that excessive interference with the driver's steering can be prevented. As described above, according to the driver state, it is possible to perform steering assistance while controlling the driver while guiding the driver so as to maintain the traveling path while appropriately participating in the driver.

  In this embodiment, the driver's degree of consciousness reduction is detected by the arousal level DA or the absurdity DL, but only the arousal level detection device 35 or the absurdity detection device 36 is used. You may comprise with the apparatus provided. Further, even if the degree of arousal is lower than the arousal level DA or the illness level DL, the same effect can be produced as long as the degree of decrease in the driver's consciousness can be determined.

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 13 Electric motor (steering means)
20 Steering control unit 20a Forward gaze distance calculating unit 20b Target passing point calculating unit (target traveling path setting means)
20c Estimated passing point calculation unit (estimated traveling path setting means)
20d Control gain setting unit (control gain setting means)
20e Control amount calculation unit (steering control amount calculation means)
21 Motor drive part (steering means)
31 Vehicle speed sensor 32 Yaw rate sensor 33 Forward recognition device (forward information detection means)
34 Release state detection device (hand release state detection means)
35 Arousal level detection device (Driving consciousness degree detection means)
36 Degree detection device (Driving consciousness degree detection means)

Claims (3)

Forward information detecting means for detecting traveling road information ahead of the host vehicle;
Driving state detection means for detecting the driving state of the host vehicle;
Target travel path setting means for setting a target travel path of the host vehicle based on the travel path information ahead of the host vehicle;
An estimated traveling path setting means for setting an estimated traveling path predicted to travel by the host vehicle based on the current driving state of the host vehicle;
A release state detection means for detecting a release state from the steering wheel of the driver;
A driving consciousness reduction degree detecting means for detecting a driving consciousness reduction degree;
Control gain setting means for variably setting the control gain according to one of the hand-off state and the degree of decrease in driving awareness of the driver;
Steering control amount calculating means for calculating a steering control amount for the host vehicle to travel on the target traveling path based on the driving state of the host vehicle, the target traveling path, the estimated traveling path, and the control gain;
And a steering means for steering based on the steering control amount,
The control gain setting means, when detecting the release state, sets the control gain in such a direction that the settling time until the own vehicle converges on the target traveling path is shortened as the time of the release state increases. A steering assist control device for a vehicle. The driving consciousness degree detection means detects the degree of decrease in driving consciousness of the driver as a stepwise awakening level, detects the degree of reduction in driving awareness of the driver as a gradual level of awakening, and of absentminded degree using either be one that detects an operation awareness decrease the degree of the driver, the alertness is high, or when the aimless degree is low, the driver awareness decrease the degree of the driver low intent judgment, the alertness is low, or if the aimless high degree, the steering assist control apparatus for a vehicle according to claim 1, wherein the driving consciousness decline degree of the driver high the Most judges. When the release state is not detected , the control gain setting means controls the control gain direction so that the settling time until the host vehicle converges on the target travel path becomes shorter as the degree of decrease in driving consciousness of the driver is higher. The vehicle steering assist control apparatus according to claim 1 or 2, wherein a gain is set.

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