JP6662189B2 - Driving support method and driving support device - Google Patents

Description

  The present invention relates to a driving support method and a driving support device.

  A driving support device that sets a following target trajectory so that a vehicle equipped with an electric power steering (EPS) system follows a preceding vehicle, and controls a steering angle so that the vehicle passes on the following target trajectory. Has been proposed (for example, Patent Document 1).

JP 2015-209143 A

When the steered angle is controlled so as to follow the following target trajectory so as to follow the preceding vehicle, the steered angle changes in accordance with a change in the lateral position of the preceding vehicle. In a vehicle that employs an EPS system in which the steered wheels and the steering wheel are mechanically connected, a change in the steering angle is transmitted to the steering wheel. Changes may give the driver a sense of discomfort.
SUMMARY OF THE INVENTION It is an object of the present invention to suppress a driver's uncomfortable feeling by reducing a change in a steering angle and a change in a steering torque when a vehicle performs a steering control so as to follow a preceding vehicle.

  In a driving support method according to one aspect of the present invention, a steering reaction force is controlled in accordance with a steering operation of a steering wheel or a steering angle of a steered wheel of a vehicle including a steer-by-wire steering mechanism. Further, a first deviation between the lateral position of the vehicle and the lateral position of the preceding vehicle is detected. The first steering control for controlling the steered angle of the steered wheels so as to reduce the first deviation is executed. When the first steering control is being performed, a first steering reaction force that encourages the vehicle to follow the preceding vehicle is applied to the steering wheel based on the steering angle of the steered wheels and the turning curvature of the preceding vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, when steering control is performed so that a vehicle follows a preceding vehicle, a driver's uncomfortable feeling can be suppressed by reducing a change in the steering angle of the steering and a change in the steering torque.

FIG. 2 is a block diagram illustrating a configuration example of a steering system of a vehicle equipped with the driving support device. It is explanatory drawing of an example of the lateral position deviation Dv1 of a vehicle and a preceding vehicle. FIG. 9 is an explanatory diagram of an example of a lateral position deviation Dv2 between a traveling locus of a preceding vehicle and a lateral position of the vehicle. FIG. 3 is a block diagram illustrating a configuration example of a steering control unit. It is a block diagram showing an example of composition of a lane keep (LK) command turning angle calculation part. It is a block diagram showing the example of a structure of a repulsion calculation part. It is a block diagram showing the example of a structure of a reaction force control part. FIG. 9 is an explanatory diagram of an example of a steering reaction force characteristic curve that determines a steering reaction force applied according to a steering angle. FIG. 3 is a block diagram illustrating a configuration example of an offset amount calculation unit. FIG. 4 is a block diagram illustrating a configuration example of a reaction torque correction value calculation unit. It is explanatory drawing of an example of the lateral position deviation-reaction map used for calculation of the reaction force N_THW according to a lateral position deviation. 4 is a flowchart illustrating an example of a driving support method according to the first embodiment. FIG. 7 is an explanatory diagram of an example of a lateral position deviation Dv1 between a vehicle and a preceding vehicle and a lateral position deviation Dr between a vehicle and a reference traveling track. FIG. 7 is an explanatory diagram of a setting example of a steering reaction force mixture ratio K according to a lateral position deviation Dv1 between a vehicle and a preceding vehicle. It is a block diagram showing the example of composition of the 1st deviation operation part in a 2nd embodiment. It is a flowchart showing an example of the driving support method of the second embodiment. 9 is a flowchart illustrating an example of a first control calculation process. 9 is a flowchart illustrating an example of a second control calculation process. 13 is a flowchart illustrating an example of a third control calculation process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1st Embodiment)
(Constitution)
Please refer to FIG. A vehicle equipped with the driving support device according to the first embodiment includes a steering unit 1, a steering unit 2, a backup clutch 3, and an SBW controller 4. The vehicle includes an SBW steering mechanism in which a steering unit 1 that receives a driver's steering input and a steering unit 2 that steers left and right front wheels 5FL and 5FR, which are steered wheels, are mechanically separated.

The steering unit 1 includes a steering wheel 1a, a column shaft 1b, a steering torque sensor 1c, a reaction motor 1d, a reaction motor drive circuit 1e, a steering angle sensor 1f, and a current sensor 1g.
The steering wheel 1a rotates in response to a driver's steering input.
The column shaft 1b rotates integrally with the steering wheel 1a.
The steering torque sensor 1c detects a steering torque transmitted from the steering wheel 1a to the column shaft 1b. This steering torque sensor 1c detects a steering torque by detecting, for example, a torsional angle displacement of a torsion bar with a potentiometer. The steering torque sensor 1c outputs the detected steering torque to the SBW controller 4.

The reaction force motor 1d has an output shaft arranged coaxially with the column shaft 1b. The reaction motor 1d outputs a steering reaction torque to be applied to the steering wheel 1a to the column shaft 1b in accordance with a command current output from the reaction motor driving circuit 1e.
The reaction motor driving circuit 1e is a torque for matching the actual steering reaction torque estimated from the current value of the reaction motor 1d detected by the current sensor 1g with the command steering reaction torque output from the SBW controller 4. The feedback controls the command current output to the reaction motor 1d.
The steering angle sensor 1f detects the rotation angle of the column shaft 1b, that is, the steering angle (handle angle) of the steering wheel 1a. Then, the steering angle sensor 1f outputs the detected steering angle to the SBW controller 4.

The turning section 2 includes a pinion shaft 2a, a steering gear 2b, a turning motor 2c, a turning motor drive circuit 2d, a turning angle sensor 2e, a rack gear 2f, and a steering rack 2g.
The steering gear 2b steers the left and right front wheels 5FL and 5FR in accordance with the rotation of the pinion shaft 2a. As the steering gear 2b, for example, a rack and pinion type steering gear or the like may be adopted.

The steering motor 2c has an output shaft connected to the rack gear 2f via a speed reducer. The turning motor 2c outputs a turning torque for turning the left and right front wheels 5FL, 5FR to the steering rack 2g according to a command current output from the turning motor drive circuit 2d. For example, the steering motor 2c may be a brushless motor or the like.
The turning angle sensor 2e detects the turning angle of the turning motor 2c, and detects the turning angles of the left and right front wheels 5FL and 5FR based on the detected turning angle.
The turning motor drive circuit 2d controls the command current to the turning motor 2c by angle feedback that matches the actual turning angle detected by the turning angle sensor 2e with the command turning angle from the SBW controller 4. I do.

The backup clutch 3 is provided between the column shaft 1b and the pinion shaft 2a. The backup clutch 3 mechanically disconnects the steering unit 1 and the steering unit 2 when the backup clutch 3 is released, and mechanically connects the steering unit 1 and the steering unit 2 when the backup clutch 3 is engaged.
Further, the vehicle includes an external recognition sensor 6 and a vehicle speed sensor 7.
The outside world recognition sensor 6 detects a preceding vehicle traveling ahead of the vehicle. Further, the outside world recognition sensor 6 detects an image of a traveling path ahead of the vehicle. The external recognition sensor 6 may include a laser distance meter and a camera. The external world recognition sensor 6 outputs a detection result and an image of the preceding vehicle to the SBW controller 4.
The vehicle speed sensor 7 detects the vehicle speed of the vehicle. The vehicle speed sensor 7 outputs the detected vehicle speed to the SBW controller 4.

The SBW controller 4 includes a steering angle sensor 1f, a steering torque sensor 1c, a current sensor 1g, an external field recognition sensor 6, and a steering angle output from the vehicle speed sensor 7, a steering torque, a current value of the reaction motor 1d, and detection of a preceding vehicle. As a result, the image of the traveling road ahead of the vehicle and the vehicle speed are received. For example, the SBW controller 4 is an electronic control unit (ECU: Electronic Control Unit) including a CPU (Central Processing Unit) and CPU peripheral components such as a ROM (Read Only Memory) and a RAM (Random Access Memory). Good.
The SBW controller 4 may receive the steering angle, the steering torque, the current value of the reaction motor 1d, the image of the traveling road, and the vehicle speed via a controller area network (CAN) bus.

The SBW controller 4 includes an image processing unit 11, a vehicle state setting unit 12, a control state setting unit 13, a turning control unit 14, and a reaction force control unit 15. The CPU of the SBW controller 4 executes a computer program stored in a storage medium to execute an image processing unit 11, a vehicle state setting unit 12, a control state setting unit 13, a steering control unit 14, and a reaction force control unit. Then, the following processing performed by step 15 is executed.
The image processing unit 11, the vehicle state setting unit 12, the control state setting unit 13, the turning control unit 14, and the reaction force control unit 15 may be independent circuits or devices.

The image processing unit 11 performs image processing such as edge extraction on the image of the traveling road ahead of the vehicle acquired from the external recognition sensor 6, so that the left and right traveling road dividing lines of the traveling lane in which the vehicle travels, that is, Detect white lines. In practice, the road segmentation line may be a yellow line or a broken line.
In addition, when there is no road white line or it is difficult to detect it, road shoulders, curbs, gutters, guard rails, protective fences, soundproof walls, retaining walls, median strips, etc. are detected as travel road division lines instead of road white lines. You may make it.
The image processing unit 11 outputs the detection results of the lane markings on the left and right sides of the traveling lane to the vehicle state setting unit 12. Hereinafter, the detection results of the lane markings on the left and right of the traveling lane may be referred to as “white line information”.

The vehicle state setting unit 12 receives the detection result of the preceding vehicle, the steering torque, the current value of the reaction force motor 1d, the vehicle speed, and the turn signal via the CAN bus. Further, the vehicle state setting unit 12 receives white line information from the image processing unit 11.
The vehicle state setting unit 12 performs a steering control by the steering control unit 14 and a reaction force control unit 15 based on the detection result of the preceding vehicle, the steering torque, the current value of the reaction force motor 1d, the vehicle speed, the blinker operation signal, and the white line information. The following variables used for steering reaction force control and lane keeping (lane keep (LK: Lane Keep)) support control are calculated.

In the steering control, the steering angle is controlled according to the steering angle and the steering angular speed of the steering wheel 1a that is steered by the driver.
In the steering reaction force control, the steering reaction force applied to the steering wheel 1a is controlled according to the steering angle or the turning angle.
In the LK support control, the turning control unit 14 controls the turning angle according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle, in addition to the steering angle and the steering angular speed of the steering wheel 1a steered by the driver. Then, the steered wheels are steered in a direction in which the vehicle follows the preceding vehicle.

  Please refer to FIG. Reference numeral 90 denotes a vehicle whose turning angle is controlled by the LK support control, and reference numeral 91 denotes a lateral position of the vehicle 90, that is, a lateral position (ie, a width direction) in a traveling lane. Reference numeral 92 indicates a preceding vehicle of the vehicle 90, and reference numeral 93 indicates a lateral position of the preceding vehicle 92. The lateral position deviation Dv1 is a difference between the lateral position 91 of the vehicle 90 and the lateral position 93 of the preceding vehicle 92.

Here, as the lateral position of the vehicle 90, a lateral position of a scheduled position to be reached when the vehicle 90 travels forward from the current position for a predetermined delay time (for example, 0.5 seconds) may be used.
In the following description, the travel distance when the vehicle travels forward by a predetermined delay time may be referred to as “scheduled travel distance”. In addition, a scheduled position reached when the vehicle travels forward from the current position by a predetermined delay time, that is, when the vehicle travels from the current position for a predetermined travel distance, may be referred to as a “scheduled arrival position”.

Please refer to FIG. In the LK support control, the reaction force control unit 15 applies a steering reaction force to the steering wheel 1a in a direction in which the vehicle follows the preceding vehicle. Here, in a vehicle equipped with an SBW-type steering mechanism, since the left and right front wheels 5FL and 5FR, which are steered wheels, are separated from the steering wheel 1a, the steering angle and the steering reaction force applied to the steering wheel 1a are individually determined. Can be controlled.
Therefore, the turning curvature of the preceding vehicle is calculated, and the steering reaction force applied to the steering wheel 1a is controlled based on the steering angle or the turning angle and the turning curvature of the preceding vehicle.

  As described above, by controlling the steering reaction force based on the turning curvature, which changes less frequently, instead of the lateral position of the preceding vehicle that fluctuates relatively frequently, the steering angle and the steering due to the lateral position of the preceding vehicle are controlled. The change in torque can be reduced. As a result, it is possible to cause the steering wheel 1a to perform an operation that is more calm than the turning angle, thereby preventing the driver from feeling uncomfortable. Hereinafter, the steering reaction force controlled based on the steering angle or the turning angle and the turning curvature may be referred to as “steering reaction force according to the turning curvature”.

When the steering reaction force is applied based on the turning curvature in this way, even if there is a deviation in the lateral position between the preceding vehicle and the vehicle, the steering reaction force for reducing the deviation cannot be applied unless the preceding vehicle is turning. Therefore, in the LK support control, the reaction force control unit 15 calculates an approximate curve of the traveling locus of the preceding vehicle and calculates the steering reaction force in the direction of decreasing the lateral position deviation Dv2 between the approximate curve of the traveling locus and the vehicle by the steering wheel 1a. Add to
Please refer to FIG. A dashed line 94 indicates the actual traveling locus of the preceding vehicle 92, reference numeral 95 indicates a history of detection positions of the preceding vehicle 92 sequentially detected in a predetermined cycle, and a dashed line 96 indicates a position 95 of the preceding vehicle 92. 9 shows an approximate curve of a traveling locus of the preceding vehicle 92 calculated by complementation. Further, reference numeral 97 indicates a scheduled arrival position reached when the vehicle 90 has traveled from the current position by a scheduled travel distance.

The lateral position deviation Dv2 is a difference in lateral position between the scheduled arrival position 97 and the approximate curve 92 of the traveling locus. The lateral position difference between the current position of the vehicle 90 and the approximate curve 92 may be used as the lateral position deviation Dv2. Hereinafter, these are collectively referred to as “lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle”.
As is apparent from FIG. 3, if the period for detecting the position 95 of the preceding vehicle 92 is appropriately set, the detection position of the preceding vehicle 92 often deviates from the actual peak position P of the traveling locus 94. Therefore, the lateral variation of the approximate curve 92 of the traveling locus is smaller than the lateral variation of the actual traveling locus 94, that is, the lateral position of the preceding vehicle. That is, the approximate curve 92 of the traveling locus becomes slower than the actual traveling locus 94.
In this way, by controlling the steering reaction force based on the approximate curve 92 of the traveling locus with less change instead of the lateral position of the preceding vehicle, it is possible to reduce the change in the steering angle and the steering torque. As a result, it is possible to cause the steering wheel 1a to perform an operation that is more calm than the turning angle, thereby preventing the driver from feeling uncomfortable. Hereinafter, the steering reaction force controlled based on the approximate curve 92 of the traveling locus may be referred to as “steering reaction force according to the traveling locus”.

Please refer to FIG. The vehicle state setting unit 12 includes a gain calculation unit 12a, a travel path calculation unit 12b, a curvature calculation unit 12c, a first deviation calculation unit 12d, a second deviation calculation unit 12e, and a steering intention determination unit 12f.
The gain calculating unit 12a calculates a first vehicle speed sensitive gain, a second vehicle speed sensitive gain, a third vehicle speed sensitive gain, a gain according to a turn signal operation, a first vehicle speed sensitive rate limiter, and a second vehicle speed sensitive rate limiter.
The first vehicle speed sensitive gain is a gain that increases or decreases the amount of change in the turning angle that is changed according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle in the LK support control according to the vehicle speed.

The second vehicle speed sensitive gain is a gain that increases or decreases the amount of change in the turning angle that changes according to the steering angular speed of the steering wheel 1a according to the vehicle speed.
The third vehicle speed sensitive gain increases or decreases the steering reaction force corresponding to the traveling locus applied to the steering wheel 1a in accordance with the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle in the LK support control according to the vehicle speed. Gain.
The gain calculation unit 12a calculates the first to third vehicle speed-sensitive gains based on a vehicle speed-sensitive gain map that determines a relationship between a predetermined vehicle speed and the first to third vehicle speed-sensitive gains, respectively. For example, in the vehicle speed sensitive gain map, the gain becomes the maximum value between the vehicle speed of zero and the first vehicle speed threshold, decreases as the vehicle speed increases from the first vehicle speed threshold to the second vehicle speed threshold, and the vehicle speed becomes the minimum at the second vehicle speed threshold. The map may be a value (for example, 0).

The gain according to the turn signal operation suppresses the amount of change in the turning angle changed according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle in the LK support control, and the steering reaction force according to the traveling locus during the turn signal operation. Gain.
The gain according to the turn signal operation becomes 0, for example, after a lapse of a fixed time (for example, 3 seconds) from the start of the turn signal operation.

The first vehicle speed-sensitive rate limiter is an upper limit value for limiting the change speed of the turning angle changed in the LK support control, and the second vehicle speed-sensitive rate limiter limits the change speed of the steering reaction force changed in the LK support control. Is the upper limit. The vehicle state setting unit 12 sets these upper limits smaller when the vehicle speed is higher than when the vehicle speed is lower.
The gain calculating unit 12a outputs the first vehicle speed sensitive gain, the second vehicle speed sensitive gain, the gain according to the turn signal operation, and the first vehicle speed sensitive rate limiter to the steering control unit 14.
The gain calculation unit 12a outputs the third vehicle speed sensitive gain, the gain according to the turn signal operation, and the second vehicle speed sensitive rate limiter to the reaction force control unit 15.

The travel locus calculation unit 12b calculates the absolute position of the preceding vehicle based on the relative position of the preceding vehicle to the vehicle detected by the external recognition sensor 6, travel distance information of the vehicle, and turning state information indicating the turning state of the vehicle. . The running locus calculation unit 12b calculates an approximate curve of the running locus of the preceding vehicle by supplementing the history of the absolute position of the preceding vehicle that has been sequentially calculated at predetermined intervals. The travel locus calculation unit 12b outputs information on the approximate curve of the travel locus of the preceding vehicle to the curvature calculation unit 12c and the second deviation calculation unit 12e.
The curvature calculating unit 12c calculates the turning curvature Rv of the preceding vehicle based on the information on the approximate curve of the traveling locus output by the traveling locus computing unit 12b. The curvature calculation unit 12c outputs the turning curvature Rv to the reaction force control unit 15.

The first deviation calculator 12d calculates a lateral position deviation Dv1 between the vehicle and the preceding vehicle based on the relative position of the preceding vehicle detected by the external recognition sensor 6. The first deviation calculating unit 12d outputs the lateral position deviation Dv1 to the steering control unit 14.
The second deviation calculating unit 12e calculates a lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle based on the information on the approximate curve of the traveling locus output by the traveling locus computing unit 12b. The second deviation calculating unit 12e outputs the lateral position deviation Dv2 to the reaction force control unit 15.
The steering intention determination unit 12f determines the presence or absence of the driver's steering intention according to the steering torque detected by the steering torque sensor 1c. For example, the steering intention determination unit 12f determines that there is a steering intention when the steering torque is equal to or greater than the threshold, and determines that there is no steering intention when the steering torque is less than the threshold. The steering intention determination unit 12f outputs the determination result of the steering intention to the control state setting unit 13.

  The control state setting unit 13 receives the vehicle speed, the turn signal, the lateral acceleration detection signal, the SBW system abnormality detection signal, the brake lamp lighting signal, the lane keep switch on / off signal, and the detection result of the preceding vehicle via the CAN bus. Receive. In addition, the control state setting unit 13 receives a vehicle dynamics control (VDC) activation signal and an antilock brake system (ABS) activation signal via a CAN bus. Further, the control state setting unit 13 receives the result of the determination of the driver's steering intention from the steering intention determination unit 12f.

The control state setting unit 13 sets the LK support control flag to ON when all of the following LK support control permission conditions (A1) to (A10) are satisfied. The control state setting unit 13 turns off the LK support control flag when any of the following LK support control permission conditions (A1) to (A10) is not satisfied.
(A1) The lane keep switch is on.
(A2) A preceding vehicle is detected.
(A3) The vehicle speed is equal to or higher than the threshold.
(A4) The turn signal is not operating.
(A5) No abnormality of the SBW system is detected.
(A6) The road curvature is larger than the threshold.
(A7) The lateral acceleration is smaller than the threshold.
(A8) Neither VDC nor ABS is operating.
(A9) The brake lamp is not lit.
(A10) There is a driver's steering intention.
The control state setting unit 13 outputs an LK support control flag to the steering control unit 14 and the reaction force control unit 15.

The turning control unit 14 receives a steering angle and a vehicle speed via a CAN bus. Further, the turning control unit 14 receives the first vehicle speed sensitive gain, the third vehicle speed sensitive gain, the gain according to the turn signal operation, and the first vehicle speed sensitive rate limiter from the gain calculating unit 12a. Further, the turning control unit 14 receives the lateral position deviation Dv1 between the vehicle and the preceding vehicle from the first deviation calculating unit 12d.
The turning control unit 14 calculates a command for controlling the turning angles of the left and right front wheels 5FL, 5FR based on the received information.

When the LK support control flag is off, the turning control unit 14 outputs the basic command turning angle calculated based on the steering angle and the steering angular velocity to the turning motor drive circuit 2d as the command turning angle. That is, the steering control unit 14 steers the left and right front wheels 5FL and 5FR, which are steered wheels, in accordance with the steering operation of the steering wheel 1a by the driver.
When the LK support control flag is on, the turning control unit 14 turns the left and right front wheels 5FL and 5FR so as to decrease the lateral position deviation Dv1 according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle. The command steering angle is calculated. The turning control unit 14 outputs a command turning angle obtained by adding the LK command turning angle to the basic command turning angle to the turning motor drive circuit 2d.
That is, the turning control unit 14 turns the left and right front wheels 5FL and 5FR in accordance with the steering operation of the steering wheel 1a by the driver, and turns the left and right front wheels 5FL and 5FR so that the vehicle follows the preceding vehicle. .

The reaction force control unit 15 receives a steering angle and a vehicle speed via a CAN bus. Further, the reaction force control unit 15 receives the third vehicle speed sensitive gain, the gain according to the turn signal operation, and the second vehicle speed sensitive rate limiter from the gain calculating unit 12a. Further, the turning control unit 14 receives the turning curvature Rv of the preceding vehicle and the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle from the curvature calculating unit 12c and the second deviation calculating unit 12e, respectively.
The reaction force control unit 15 calculates a command steering reaction torque for controlling the steering reaction torque applied to the column shaft 1b based on the received information.

  When the LK support control flag is off, the reaction force control unit 15 estimates the steering rack axial force according to the steering angle or the turning angle, and instructs the target reaction force torque calculated based on the steering rack axial force to the command steering. It is output to the reaction motor drive circuit 1e as a reaction torque. The steering rack axial force is an axial force applied to the steering rack 2g according to a steering angle corresponding to the steering angle in a conventional steering device in which the steering unit and the steering unit are mechanically connected. Hereinafter, the steering rack axial force is simply referred to as “rack axial force”.

When the LK support control flag is on, the reaction force control unit 15 offsets the rack axial force estimated according to the steering angle or the turning angle according to the turning curvature Rv of the preceding vehicle. By offsetting the rack axial force in this manner, a steering reaction force for maintaining a steering angle for following the preceding vehicle and turning the vehicle (that is, a steering reaction force for promoting steering for following the preceding vehicle and turning the vehicle). ) Is generated as a steering reaction force corresponding to the steering angle or the turning angle and the turning curvature. The reaction force control unit 15 calculates a target reaction force torque based on the rack axial force after the offset.
Further, the reaction force control unit 15 corrects the target reaction torque in accordance with the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle, so that the approximate curve of the traveling locus and the lateral position deviation Dv2 between the vehicle and the vehicle. Is generated as a steering reaction force corresponding to the traveling locus.
The reaction force control unit 15 outputs the corrected target reaction torque to the reaction motor drive circuit 1e as a command steering reaction torque.

Please refer to FIG. The turning control section 14 includes a gain multiplying section 20, a steering angular velocity calculating section 21, a differential steer gain multiplying section 22, an LK command turning angle calculating section 23, a multiplier 24, and an adder 25.
The gain multiplication unit 20 multiplies the steering angle detected by the steering angle sensor 1f by a gain and outputs the result to the adder 25.
The steering angular velocity calculator 21 calculates the steering angular velocity of the steering wheel 1a based on the steering angle detected by the steering angle sensor 1f, and outputs the result to the differential steer gain multiplier 22. The differential steer gain multiplying unit 22 multiplies the steering angular velocity by the differential steer gain and outputs the result to the multiplier 24. The multiplier 24 multiplies the operation result of the differential steer gain multiplying unit 22 by the second vehicle speed sensitive gain and outputs the result to the adder 25.

The LK command turning angle calculation unit 23 receives the first vehicle speed sensitive gain, the gain according to the turn signal operation, the first vehicle speed sensitive rate limiter, the lateral position deviation Dv1 between the vehicle and the preceding vehicle, and the vehicle speed. The LK command turning angle calculation unit 23 calculates an LK command turning angle for turning in the returning direction to reduce the lateral position deviation Dv1 between the vehicle and the preceding vehicle based on the received information. The LK command turning angle calculation unit 23 outputs the LK command turning angle to the adder 25.
When the LK support control flag is off, the adder 25 calculates the basic command turning angle by adding the calculation result of the gain multiplying unit 20 and the calculation result of the multiplier 24, and gives the calculated basic command turning angle to the command. The steering angle is output to the steering motor drive circuit 2d as a steering angle.
When the LK support control flag is on, the adder 25 calculates the command turning angle by adding the calculation result of the gain multiplying unit 20, the calculation result of the multiplier 24, and the LK command turning angle, and Output to the circuit 2d.

Please refer to FIG. The LK command steering angle calculator 23 includes a repulsive force calculator 40, a target yaw moment calculator 43, a target yaw acceleration calculator 44, a target yaw rate calculator 45, a command steer angle calculator 46, and a limiter. A processing unit 47 is provided.
The repulsive force calculation unit 40 receives the first vehicle speed sensitive gain, the gain according to the turn signal operation, and the lateral position deviation Dv1 between the vehicle and the preceding vehicle. The repulsive force calculator 40 performs the lateral position deviation feedback control based on the received information.

In the lateral position deviation feedback control, a vehicle repulsion force for reducing a change in the lateral position deviation Dv1 caused by disturbance or movement of a preceding vehicle is calculated. Hereinafter, this repulsion may be referred to as “repulsion according to the lateral position deviation”. Thus, in the lateral position deviation feedback control, the turning angles of the left and right front wheels 5FL and 5FR are controlled in a direction in which the lateral position deviation Dv1 decreases based on the lateral position deviation Dv1.
Please refer to FIG. The repulsive force calculator 40 includes a gain multiplier 40a and a multiplier 40b. The gain multiplication unit 40a multiplies the lateral position deviation Dv1 by a basic gain and outputs a calculation result to the multiplier 40b.
The multiplier 40b multiplies the calculation result of the gain multiplication unit 40a, the first vehicle speed-sensitive gain, and the gain according to the turn signal operation to calculate a repulsive force according to the lateral position deviation.

Please refer to FIG. The repulsive force calculation unit 40 outputs the calculation result to the target yaw moment calculation unit 43.
The target yaw moment calculating section 43 calculates a target yaw moment based on the repulsive force according to the lateral position deviation output from the repulsive force calculating section 40. Specifically, the target yaw moment calculating section 43 calculates the target yaw moment M * according to the following equation (1) based on the repulsion force according to the lateral position deviation, the wheelbase WHEELBASE, the rear wheel axle weight, and the front wheel axle weight. Is calculated. Then, the target yaw moment calculator 43 outputs the calculation result to the target yaw acceleration calculator 44.
M * = (repulsive force according to lateral position deviation) × (rear wheel axle weight / (front wheel axle weight + rear wheel axle weight)) × WHEELBASE (1)

The target yaw acceleration calculator 44 calculates a target yaw acceleration based on the target yaw moment M * output from the target yaw moment calculator 43. Specifically, the target yaw acceleration calculating section 44 multiplies the target yaw moment by a predetermined yaw inertia moment coefficient. Then, the target yaw acceleration calculator 44 outputs the multiplication result to the target yaw rate calculator 45 as the target yaw acceleration.
The target yaw rate calculator 45 calculates a target yaw rate, which is a change speed of the yaw angle, based on the target yaw acceleration output from the target yaw acceleration calculator 44. Specifically, the target yaw rate calculator 45 multiplies the target yaw acceleration by a predetermined delay time. Then, the target yaw rate calculator 45 outputs the multiplication result to the command steering angle calculator 46 as a target yaw rate.

The command steering angle calculation unit 46 calculates the LK command steering angle based on the target yaw rate and the vehicle speed output by the target yaw rate calculation unit 45. Specifically, the command turning angle calculation unit 46 calculates the LK command turning angle δst * according to the following equation (2) based on the target yaw rate φ *, the vehicle speed V, the wheel base WHEELBASE, and the characteristic speed Vch of the vehicle. calculate. Here, the characteristic speed Vch may be, for example, a parameter representing a self-steering characteristic of the vehicle in a known Ackerman equation. Then, the command turning angle calculation unit 46 outputs the calculation result to the limiter processing unit 47.
δst * = (φ * × WHEELBASE × (1+ (V / Vch) 2) × 180) / (V × MPI) (2)
MPI is a predetermined coefficient.

  The limiter processing unit 47 limits the upper limit of the change speed of the LK command turning angle δst * by the first vehicle speed sensitive rate limiter. In addition, the limiter 47 limits the maximum value of the LK command steering angle δst *. The maximum value of the LK command steering angle δst * is within a play range when the steering angle of the steering wheel 1a is near the neutral position in a conventional steering device in which the steering unit and the steering unit are mechanically connected. The steering angle ranges of the corresponding left and right front wheels 5FL, 5FR may be used. Then, limiter processing section 47 outputs the LK command steering angle δst * after the restriction to adder 25 (see FIG. 4).

Please refer to FIG. The reaction force control unit 15 includes a rack axial force calculation unit 60, an offset amount calculation unit 61, a subtractor 62, a target reaction force torque calculation unit 63, a reaction force torque correction value calculation unit 64, and an adder 65. Prepare.
The rack axial force calculating unit 60 estimates the rack axial force based on the steering angle and the vehicle speed with reference to a steering angle-axial force conversion map (MAP). That is, the rack axial force calculation unit 60 estimates the rack axial force based on the steering angle and the vehicle speed and the steering angle-axial force conversion map. The rack axial force calculation unit 60 may receive the steered angles of the steered angles of the left and right front wheels 5FL, 5FR from the steered angle sensor 2e, and estimate the rack axial force based on the steered angle and the vehicle speed.
For example, the steering angle-axial force conversion map is a map representing the relationship between the steering angle for each vehicle speed and the rack axial force in a conventional steering device calculated in advance through experiments or the like. The rack axial force calculator 60 outputs the calculation result to the subtractor 62.

The offset calculation unit 61 calculates the axial force offset based on the turning curvature Rv of the preceding vehicle, and outputs the calculated axial force offset to the subtractor 62. The target reaction torque calculation unit 63 calculates the steering reaction torque based on the rack axial force after being offset by the axial force offset amount, that is, a difference obtained by subtracting the axial force offset amount from the rack axial force.
The amount of axial force offset is set so that a steering reaction force for maintaining a steering angle for turning the vehicle following the preceding vehicle (that is, a steering reaction force for encouraging steering for turning the vehicle following the preceding vehicle) is generated. , The offset amount for offsetting the rack axial force.
By offsetting the rack axial force, a steering reaction force characteristic curve indicating the relationship between the steering angle of the steering wheel 1a and the steering reaction force to be applied to the steering wheel 1a in accordance with the steering angle is offset.

Referring to FIG. The horizontal axis indicates the steering angle of the steering wheel 1a, and the vertical axis indicates the steering reaction force corresponding to the steering reaction torque calculated by the target reaction torque calculation unit 63. Here, the sign of the steering angle turning right, that is, the clockwise steering angle is plus, and the sign of the steering angle turning left, that is, the counterclockwise steering angle is minus. Further, the sign of the steering reaction force in the counterclockwise direction is plus, and the sign of the steering reaction force in the clockwise direction is minus.
A dotted line 66 indicates a steering reaction force characteristic curve in a state where the rack axial force is not offset, that is, in a state where the axial force offset amount is zero. In the steering reaction force characteristic curve 66, the steering reaction force becomes zero when the steering angle is zero, so that no steering reaction force that maintains the steering angle for turning the vehicle, that is, that encourages the steering to turn the vehicle, is generated. .

On the other hand, the solid line 67 indicates a steering reaction force characteristic curve in a state where the rack axial force is offset, that is, a state where the axial force offset amount is a positive non-zero value. Here, the sign of the axial force offset amount when the preceding vehicle is turning right is plus, and the sign of the axial force offset amount when the preceding vehicle is turning left is minus.
When the axial force offset amount is a positive non-zero value, the steering reaction force characteristic curve 67 is offset in a positive direction. As a result, the steering angle θ1 at which the steering reaction force becomes zero moves in the positive direction, so that the steering reaction force for maintaining the steering angle for turning the vehicle to the right (that is, the steering for urging the steering to turn the vehicle to the right). Reaction force) is generated.

  In the steering reaction force characteristic curve 67, the absolute value of the steering reaction force generated when the steering reaction force is shifted clockwise and counterclockwise by the same angle from the steering angle θ1 at which the steering reaction force becomes zero becomes the same. Therefore, when the vehicle is deviated clockwise and counterclockwise from the steering angle at which the vehicle turns following the preceding vehicle, a steering reaction force is generated evenly in the direction of returning the deviation. The steering angle at which the vehicle turns can be maintained without discomfort.

Please refer to FIG. The offset amount calculating section 61 includes an upper / lower limiter 61a, a self-aligning torque (SAT) gain calculating section 61b, a multiplier 61c, and a limiter processing section 61d.
The upper / lower limiter 61a performs an upper / lower limiter process on the vehicle speed output from the vehicle speed sensor 7. In the upper / lower limiter processing, for example, the vehicle speed increases as the vehicle speed increases in a range of 0 to V (> 0), and reaches a maximum value in a range of the vehicle speed of V or higher. Then, the upper / lower limiter 61a outputs the vehicle speed after the upper / lower limiter processing to the SAT gain calculator 61b.

  The SAT gain calculation unit 61b calculates an SAT gain according to the vehicle speed based on the vehicle speed after the limiter output from the upper and lower limiter 61a. The SAT gain according to the vehicle speed increases, for example, as the vehicle speed increases in a range of 0 to 70 km / h, and reaches a maximum value in a range of 70 km / h or more. Further, when the vehicle speed is high, the change amount of the SAT gain with respect to the vehicle speed change amount is larger than when the vehicle speed is low. Then, the SAT gain calculator 61b outputs the calculation result to the multiplier 61c.

The multiplier 61c multiplies the turning curvature Rv of the preceding vehicle by the SAT gain output by the SAT gain calculator 61b. Then, the multiplier 61c outputs the multiplication result to the limiter processing unit 61d as an axial force offset amount.
The limiter processing unit 61d limits the maximum value of the axial force offset amount output from the multiplier 61c and the upper limit of the rate of change. The maximum value of the axial force offset amount is 1000N. In addition, the upper limit of the rate of change of the axial force offset amount is set to 600 N / s. Then, the limiter processing unit 61d outputs the limited axial force offset amount to the subtractor 62.

Please refer to FIG. The subtracter 62 outputs to the target reaction force torque calculation unit 63 a difference obtained by subtracting the axial force offset amount output from the offset amount calculation unit 61 from the rack axial force output from the rack axial force calculation unit 60.
The target reaction torque calculation unit 63 calculates a steering reaction torque generated by the rack axial force after the offset with reference to the axial force-steering reaction force conversion map based on the calculation result output by the subtractor 62. That is, the target reaction torque calculator 63 calculates the steering reaction torque generated by the offset rack axial force based on the offset rack axial force and the axial force-steering reaction force conversion map.

For example, the axial force-steering reaction force conversion map is a map representing the relationship between the rack axial force and the steering reaction force torque in a conventional steering device calculated in advance through experiments or the like. That is, the axial force-steering reaction force conversion map may be a map that simulates a steering reaction force characteristic representing a steering reaction torque corresponding to a self-aligning torque generated by a rack axial force in a conventional steering device. In the axial force-steering reaction force conversion map, the larger the rack axial force, the larger the steering reaction torque. In the axial force-steering reaction force conversion map, the change amount of the steering reaction force torque with respect to the change amount of the rack axial force is larger when the absolute value of the rack axial force is smaller than when it is larger. Further, in the axial force-steering reaction force conversion map, the higher the vehicle speed, the smaller the steering reaction torque.
The target reaction torque calculator 63 outputs the steering reaction torque to the adder 65.

The reaction torque correction value calculation unit 64 calculates a reaction torque based on the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle, a third vehicle speed sensitive gain, a gain according to the turn signal operation, and a second vehicle speed sensitive rate limiter. The force torque correction value is calculated and output to the adder 65.
The reaction torque correction value is a correction value that generates a steering reaction force according to a traveling locus acting in a direction that reduces the lateral position deviation Dv2.

Please refer to FIG. The reaction torque correction value calculation unit 64 includes a reaction force calculation unit 64a, a multiplier 64b, and a limiter processing unit 64c.
The reaction force calculator 64a calculates a reaction force N_THW according to the lateral position deviation by referring to the lateral position deviation-reaction force map 64d based on the lateral position output by the second deviation calculator 12e. That is, the reaction force calculating unit 64a calculates the reaction force N_THW according to the lateral position deviation based on the lateral position output by the second deviation computing unit 12e and the lateral position deviation-reaction force map 64d.

FIG. 11 shows an example of the lateral position deviation-reaction force map 64d. Here, the sign of the lateral position deviation Dv2 is determined so that the sign becomes positive when the vehicle deviates to the right of the traveling locus of the preceding vehicle and becomes negative when the vehicle deviates to the left. Also, the sign of the reaction force applied in the direction of turning to the left (ie, in the counterclockwise direction) is determined to be positive, and the sign of the reaction force applied in the direction of turning to the right (ie, in the clockwise direction) becomes negative. Stipulated.
As illustrated, the reaction force N_THW corresponding to the lateral position deviation becomes positive when the sign of the lateral position deviation Dv2 is positive, and becomes negative when the sign of the lateral position deviation Dv2 is negative. Therefore, the reaction force N_THW according to the lateral position deviation is a reaction force acting in a direction to decrease the lateral position deviation Dv2.

In addition, the absolute value of the reaction force N_THW according to the lateral position deviation is larger when the absolute value of the lateral position deviation Dv2 is large than when it is small.
Further, when the absolute value of the lateral position deviation Dv2 is large, the change amount of the reaction force N_THW according to the lateral position deviation with respect to the change amount of the lateral position deviation Dv2 is made larger than when the absolute value is small.
Therefore, the reaction force N_THW according to the lateral position deviation increases as the deviation amount of the vehicle from the traveling locus of the preceding vehicle increases.
Please refer to FIG. The reaction force calculator 64a outputs the reaction force N_THW corresponding to the lateral position deviation to the multiplier 64b as a reaction force command value.

The multiplier 64b calculates a reaction force torque command value by multiplying the reaction force command value by a third vehicle speed sensitive gain and a gain corresponding to the turn signal operation, and outputs the calculated reaction force command value to the limiter processing unit 64c.
The limiter processing section 64c limits the upper limit of the changing speed of the reaction torque command value by the second vehicle speed sensitive rate limiter. In addition, the limiter processing section 64c limits the maximum value of the reaction torque command value. The limiter processing unit 64c outputs the restricted reaction torque command value to the adder 65 (see FIG. 7) as a reaction torque correction value.

Please refer to FIG. The adder 65 calculates the command steering reaction torque by adding the reaction torque correction value calculated by the reaction torque correction value calculation unit 64 to the steering reaction torque calculated by the target reaction torque calculation unit 63, Output to the motor drive circuit 1e.
The outside world recognition sensor 6 is an example of a sensor that detects a lateral position of a preceding vehicle. The lateral position deviation Dv1 between the vehicle and the preceding vehicle is an example of a first deviation between the lateral position of the preceding vehicle and the lateral position of the vehicle. The steering reaction force according to the turning curvature is an example of a first steering reaction force that prompts the vehicle to follow the preceding vehicle based on the turning angle of the steered wheels and the turning curvature of the preceding vehicle.

(motion)
Next, a driving support method according to the first embodiment will be described. Referring to FIG.
In step S1, the first deviation calculating unit 12d calculates a lateral position deviation Dv1 between the vehicle and the preceding vehicle based on the relative position of the preceding vehicle detected by the external environment recognition sensor 6. In step S2, the traveling trajectory calculating unit 12b sets The absolute position of the preceding vehicle is calculated based on the relative position of the preceding vehicle with respect to the vehicle detected by the recognition sensor 6, travel distance information of the vehicle, and turning state information indicating the turning state of the vehicle. The running locus calculation unit 12b calculates an approximate curve of the running locus of the preceding vehicle based on the history of the absolute position of the preceding vehicle that has been sequentially calculated at predetermined intervals.
The second deviation calculator 12e calculates the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle based on the approximate curve of the traveling locus.

In step S3, the curvature calculation unit 12c calculates the turning curvature Rv of the preceding vehicle based on the approximate curve of the traveling locus output by the traveling locus computing unit 12b.
In step S4, the turning control unit 14 calculates an LK command turning angle based on the lateral position deviation Dv1 between the vehicle and the preceding vehicle. The turning control unit 14 calculates a basic command turning angle calculated based on the steering angle and the steering angular velocity. The turning control unit 14 calculates a turning angle command value by adding the LK command turning angle to the basic command turning angle.
In step S5, the reaction torque correction value calculation unit 64 calculates a reaction torque correction value based on the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle.
In step S6, the offset amount calculation unit 61 calculates the axial force offset amount based on the turning curvature Rv of the preceding vehicle.

In step S7, the rack axial force calculator 60 calculates the rack axial force according to the steering angle or the turning angle. The target reaction torque calculator 63 calculates a target reaction torque based on the rack axial force offset by the axial force offset amount. The adder 65 calculates the command steering reaction torque by correcting the reaction torque correction value by adding the reaction torque correction value to the target reaction torque.
In step S8, the turning control unit 14 outputs the command turning angle to the turning motor drive circuit 2d to perform turning control. Further, the reaction force control unit 15 outputs the command steering reaction force torque to the reaction force motor drive circuit 1e to perform the reaction force control. Thereafter, the process ends.

(Effects of the embodiment)
(1) In a vehicle provided with an SBW-type steering mechanism, the steering control unit 14 steers the steered wheels in accordance with the steering operation of the steering wheel 1a by the driver. The reaction force control unit 15 controls the steering reaction force according to the steering operation of the steering wheel 1a or the turning angle of the steered wheels. The first deviation calculator 12d detects a lateral position deviation Dv1 between the preceding vehicle and the vehicle. The turning control unit 14 executes first turning control for controlling the turning angle of the steered wheels so that the lateral position deviation Dv1 decreases. The curvature calculator 12c detects a turning curvature Rv of the preceding vehicle. When executing the first steering control, the reaction force control unit 15 applies a steering reaction force to the steering wheel 1a to encourage the vehicle to follow the preceding vehicle based on the turning curvature Rv.
Accordingly, when the vehicle performs the steering control so as to follow the preceding vehicle, a change in the steering angle and a change in the steering torque of the steering can be reduced to suppress the driver's discomfort.

That is, in a vehicle including an SBW type steering mechanism in which the left and right front wheels 5FL and 5FR, which are steered wheels, and the steering wheel 1a are mechanically separated, the steering angle and the steering reaction force applied to the steering wheel 1a are determined. Can be controlled individually. Therefore, the steering angle of the steered wheels is controlled according to the lateral position deviation Dv1 between the preceding vehicle and the vehicle, while the steering reaction force applied to the steering wheel 1a is controlled based on the turning curvature Rv of the preceding vehicle. .
As described above, the change in the steering angle and the steering torque is reduced by controlling the steering reaction force based on the turning curvature that changes less frequently, instead of the lateral position of the preceding vehicle that changes relatively frequently. Can be. As a result, it is possible to cause the steering wheel 1a to perform an operation that is more calm than the turning angle, thereby preventing the driver from feeling uncomfortable.

  (2) The rack axial force calculator 60 estimates the steering rack axial force applied to the steering rack 2g according to the steering angle of the steering wheel 1a detected by the steering angle sensor 1f. The estimated steering rack axial force is offset according to the turning curvature Rv, and the target reaction torque calculating unit 63 calculates the steering reaction torque applied to the reaction motor driving circuit 1e based on the offset steering rack axial force. This generates a steering reaction force that encourages the vehicle to follow the preceding vehicle.

  By offsetting the rack axial force, the steering reaction force characteristic curve between the steering angle of the steering wheel 1a and the steering reaction force corresponding to the steering reaction torque calculated by the target reaction torque calculator 63 is offset. You. By offsetting the steering reaction force characteristic curve, the steering angle at which the steering reaction force becomes zero can be set to a value corresponding to the turning curvature Rv. Therefore, a steering reaction force for maintaining a steering angle for turning the vehicle (that is, a steering reaction force for promoting the steering for turning the vehicle) can be generated.

  Here, in the steering reaction force characteristic curve after the offset, the absolute value of the steering reaction force generated when the steering reaction force is shifted clockwise and counterclockwise by the same angle from the steering angle at which the steering reaction force becomes zero becomes the same. . Therefore, when the vehicle is deviated clockwise and counterclockwise from the steering angle at which the vehicle turns following the preceding vehicle, a steering reaction force is generated evenly in the direction of returning the deviation. The steering angle at which the vehicle turns can be maintained without discomfort.

(2nd Embodiment)
Next, a driving assistance device according to a second embodiment will be described. In the driving support device of the second embodiment, it is determined whether or not the traveling lane of the vehicle can be recognized. When the traveling lane can be recognized, in addition to or instead of the lateral position deviation Dv1 between the preceding vehicle and the vehicle, the lateral position deviation Dr between the reference traveling trajectory set in the traveling lane and the vehicle is calculated. Based on this, the steering control is executed to control the steering angle so that the lateral position deviation Dr decreases.
Please refer to FIG. Reference numeral 98 indicates a reference traveling trajectory set in the traveling lane. The reference traveling trajectory 98 may be, for example, a center of the traveling lane or a trajectory separated from the center by a predetermined distance. The lateral position deviation Dr is a difference between the lateral position of the reference traveling track 98 and the lateral position of the vehicle 90.

If the traveling lane can be recognized, a steering reaction force that encourages the vehicle to travel along the traveling lane is applied to the steering wheel based on the road curvature Rr of the traveling lane.
By controlling the steering angle based on the lateral position deviation Dr between the reference traveling trajectory and the vehicle, and controlling the steering reaction force based on the road curvature Rr of the traveling lane, for example, LK support can be performed even when a preceding vehicle cannot be detected. Control can be performed.

  The driving support device of the second embodiment has a configuration similar to the configuration shown in FIG. Further, the turning control unit 14, the LK command turning angle calculation unit 23, the repulsion force calculation unit 40, the reaction force control unit 15, the offset amount calculation unit 61, and the reaction force torque correction value calculation unit 64 of the second embodiment include: Each has a configuration similar to the configuration shown in FIGS. 4, 5, 6, 7, 9, and 10.

Please refer to FIG. The image processing unit 11 determines whether or not the lane marking has been detected. The image processing unit 11 outputs the determination result of the detection possibility to the curvature calculation unit 12c, the first deviation calculation unit 12d, the second deviation calculation unit 12e, and the control state setting unit 13.
The curvature calculating unit 12c, the first deviation calculating unit 12d, the second deviation calculating unit 12e, and the control state setting unit 13 receive the detection result of the preceding vehicle from the external recognition sensor 6 via the CAN bus.

The control state setting unit 13 sets the LK support control flag to ON when all of the following LK support control permission conditions (B1) to (B10) are satisfied. The control state setting unit 13 turns off the LK support control flag when any of the following LK support control permission conditions (B1) to (B10) is not satisfied.
(B1) and (B3) to (B10) are the same as the LK support control permission conditions (A1) and (A3) to (A10).
(B2) A preceding vehicle has been detected or a lane marking has been detected.

(Operation when both the preceding vehicle and the lane marking are detected)
When both the preceding vehicle and the lane marking are detected, the curvature calculation unit 12c determines the road curvature Rr (the predetermined delay) of the road white line at the scheduled arrival position based on the white line information output by the image processing unit 11. The road curvature of the road white line at the position of the vehicle after a lapse of time (0.5 seconds) is calculated.
The curvature calculator 12c outputs the road curvature Rr to the reaction force controller 15 instead of the turning curvature Rv of the preceding vehicle.

  The first deviation calculating unit 12d calculates the lateral position deviation Dv1 between the vehicle and the preceding vehicle and the lateral position deviation Dr between the reference traveling path and the vehicle by using the mixing ratio K and (1-K) according to the distance between the vehicle and the preceding vehicle. ) To calculate the mixed lateral position deviation Dc. The distance between the vehicle and the preceding vehicle may be, for example, a distance between the vehicle and the preceding vehicle, or a time to collision (TTC) of the vehicle with respect to the preceding vehicle. In this example, the mixture ratio K is determined according to the inter-vehicle distance D.

Please refer to FIG. The mixture ratio K of the lateral position deviation Dv1 decreases when the inter-vehicle distance D is longer than when it is short. That is, the mixing ratio K decreases as the inter-vehicle distance D increases. Therefore, the mixture ratio (1-K) of the lateral position deviation Dr increases when the inter-vehicle distance D is longer than when it is short. That is, the mixing ratio K increases as the inter-vehicle distance D increases.
The mixture ratio K is the maximum value when the inter-vehicle distance D is in the range of 0 to D1 (> 0), is the minimum value when the inter-vehicle distance D is longer than D2 (> D1), and is the minimum value in the range of D1 to D2. Decreases as the length becomes longer.
The first deviation calculator 12d calculates the mixed lateral position deviation Dc according to the following equation (3).
Mixed lateral position deviation Dc = K × lateral position deviation Dv1 + (1−K) × lateral position deviation Dr (3)
The maximum value of the mixture ratio K may be, for example, 100%, and the minimum value may be 0%. Therefore, when the inter-vehicle distance D is in the range of 0 to D1, the mixed lateral position deviation Dc is equal to the lateral position deviation Dv1 between the vehicle and the preceding vehicle, and in the range where the inter-vehicle distance D is longer than D2, the lateral position between the reference traveling path and the vehicle. It becomes equal to the deviation Dr.

Referring to FIG. The first deviation calculating unit 12 d receives the detection result of the preceding vehicle output from the external recognition sensor 6 and the white line information output from the image processing unit 11.
The first deviation calculator 12d includes a first lateral position deviation calculator 70, a second lateral position deviation calculator 71, an inter-vehicle distance calculator 72, a mixture ratio determiner 73, multipliers 74 and 76, and subtraction. A device 75 and an adder 77 are provided.
The first lateral position deviation calculator 70 calculates a lateral position deviation Dv1 between the vehicle and the preceding vehicle based on the relative position of the preceding vehicle detected by the external recognition sensor 6. The first lateral position deviation calculator 70 outputs the lateral position deviation Dv1 to the multiplier 74.

The second lateral position deviation calculating unit 71 calculates the expected travel distance by multiplying the predetermined delay time by the vehicle speed. The second lateral position deviation calculating unit 71 calculates a yaw angle between the road white line and the traveling direction of the vehicle based on the white line information output from the image processing unit 11. The lateral position deviation Dr between the reference traveling path and the vehicle is calculated by multiplying the planned traveling distance by the yaw angle and adding the result to the distance from the reference traveling path. The second lateral position deviation calculator 71 outputs the lateral position deviation Dr to the multiplier 74.
The inter-vehicle distance calculation unit 72 calculates an inter-vehicle distance D between the vehicle and the preceding vehicle based on the detection result of the preceding vehicle output from the external recognition sensor 6. The following distance calculation unit 72 outputs the following distance D to the mixture ratio determining unit 73.

The mixture ratio determining unit 73 determines the mixture ratio K according to the inter-vehicle distance D and the mixture ratio K shown in FIG. The mixture ratio determination unit 73 outputs the mixture ratio K to the multiplier 74 and the subtractor 75. The subtractor 75 calculates the mixture ratio (1-K) by subtracting K from the constant “1”. The subtractor 75 outputs the mixture ratio (1-K) to the subtractor 75. The multiplier 74 multiplies the lateral position deviation Dv1 by the mixture ratio K, and outputs an operation result K × the lateral position deviation Dv1 to the adder 77. The multiplier 76 multiplies the lateral position deviation Dr by the mixture ratio (1−K), and outputs the calculation result (1−K) × the lateral position deviation Dr to the adder 77. The adder 77 adds K × lateral position deviation Dv1 and (1−K) × lateral position deviation Dr to output a mixed lateral position deviation Dc.
The first deviation calculating unit 12d outputs the mixed lateral position deviation Dc to the steering control unit 14 instead of the lateral position deviation Dv1 between the vehicle and the preceding vehicle.

Please refer to FIG. The second deviation calculator 12e calculates the lateral position deviation Dv2 between the traveling locus of the preceding vehicle and the vehicle as in the first embodiment. The second deviation calculating unit 12e outputs the lateral position deviation Dv2 to the reaction force control unit 15.
The steering control unit 14 performs an LK command to steer the left and right front wheels 5FL and 5FR so that the mixed lateral position deviation Dc decreases according to the mixed lateral position deviation Dc instead of the lateral position deviation Dv1 between the vehicle and the preceding vehicle. Calculate the steering angle. The operation of the turning control unit 14 is the same as the operation of the turning control unit 14 in the first embodiment except that the mixed lateral position deviation Dc is used instead of the lateral position deviation Dv1.

As described above, the mixture ratio K of the lateral position deviation Dv1 between the vehicle and the preceding vehicle included in the mixed lateral position deviation Dc decreases when the inter-vehicle distance D is longer than when the inter-vehicle distance D is short. Further, the mixture ratio (1-K) of the lateral position deviation Dr between the reference traveling path and the vehicle increases when the inter-vehicle distance D is longer than when the inter-vehicle distance D is short.
Therefore, the turning control unit 14 sets the turning amount of the turning control for controlling the turning angles of the left and right front wheels 5FL and 5FR so as to reduce the lateral position deviation Dv1 to the inter-vehicle distance D as compared with the case where the inter-vehicle distance D is short. Is reduced if it is long. That is, it is decreased as the inter-vehicle distance D becomes longer.
Further, the turning control unit 14 sets the turning amount of the turning control for controlling the turning angles of the left and right front wheels 5FL, 5FR so as to reduce the lateral position deviation Dr to the inter-vehicle distance D as compared with the case where the inter-vehicle distance D is short. Increase if it is long. That is, the distance is increased as the inter-vehicle distance D increases.

The offset amount calculation unit 61 of the reaction force control unit 15 calculates the axial force offset amount according to the road curvature Rr instead of the turning curvature Rv of the preceding vehicle. The operation of the offset amount calculation unit 61 is the same as the operation of the offset amount calculation unit 61 in the first embodiment except that the road curvature Rr is used instead of the turning curvature Rv of the preceding vehicle.
The operation of the reaction torque correction value calculator 64 of the reaction controller 15 is the same as the operation of the reaction torque correction value calculator 64 in the first embodiment.

(Operation when the lane marking is detected and the preceding vehicle cannot be detected)
When the traveling lane dividing line is detected and the preceding vehicle cannot be detected, the curvature calculating unit 12c calculates the road curvature Rr of the road white line at the scheduled arrival position based on the white line information output by the image processing unit 11. The curvature calculation unit 12c outputs the road curvature Rr to the reaction force control unit 15.
The first deviation calculating unit 12d calculates the expected travel distance by multiplying the predetermined delay time by the vehicle speed. The first deviation calculator 12d calculates the yaw angle between the road white line and the traveling direction of the vehicle based on the white line information output by the image processor 11. The lateral position deviation Dr between the reference traveling path and the vehicle is calculated by multiplying the planned traveling distance by the yaw angle and adding the result to the distance from the reference traveling path. The first deviation calculating unit 12d outputs the lateral position deviation Dr to the steering control unit 14.

The second deviation calculator 12e calculates the lateral position deviation Dr between the reference traveling trajectory and the vehicle in the same manner as the first deviation calculator 12d. The second deviation calculating unit 12e outputs the lateral position deviation Dr to the reaction control unit 15.
The turning control unit 14 calculates an LK command turning angle for turning the left and right front wheels 5FL and 5FR such that the lateral position deviation Dr decreases in accordance with the lateral position deviation Dr between the reference traveling path and the vehicle. The operation of the turning control unit 14 is the same as the operation of the turning control unit 14 in the first embodiment except that the lateral position deviation Dr is used instead of the lateral position deviation Dv1.

The offset amount calculation unit 61 of the reaction force control unit 15 calculates an axial force offset amount according to the road curvature Rr. The operation of the offset amount calculation unit 61 is the same as the operation of the offset amount calculation unit 61 in the first embodiment except that the road curvature Rr is used instead of the turning curvature Rv of the preceding vehicle.
The reaction torque correction value calculation unit 64 of the reaction control unit 15 calculates a reaction torque correction value according to the lateral position deviation Dr between the reference traveling trajectory and the vehicle. The operation of the reaction torque correction value calculation unit 64 is the first embodiment except that the lateral position deviation Dr between the reference traveling path and the vehicle is used instead of the lateral position deviation Dv2 between the traveling path of the preceding vehicle and the vehicle. The operation is the same as the operation of the reaction torque correction value calculation unit 64 in.

(Operation when the preceding vehicle is detected and the lane marking cannot be detected)
When the preceding vehicle is detected and the lane marking cannot be detected, the operations of the curvature calculator 12c, the first deviation calculator 12d, the second deviation calculator 12e, the turning control unit 14, and the reaction force control unit 15 are as follows. The operation is the same as in the first embodiment.
The lateral position deviation Dr between the reference traveling trajectory and the vehicle is an example of a second deviation of the lateral position between the reference traveling trajectory and the vehicle set in the traveling lane.

The inter-vehicle distance D is an example of an interval between the preceding vehicle and the vehicle.
The mixture ratio K is an example of a coefficient that decreases as the inter-vehicle distance between the preceding vehicle and the vehicle increases. The mixture ratio (1-K) is an example of a coefficient that increases as the inter-vehicle distance between the preceding vehicle and the vehicle increases.
The steering reaction force generated by the axial force offset amount corresponding to the road curvature Rr is an example of a second steering reaction force that prompts the vehicle to travel along a traveling lane based on the road curvature.
The image processing unit 11 is an example of a determination unit that determines whether a road curvature of a traveling road of a vehicle can be detected.

Next, a driving support method according to a second embodiment will be described. Please refer to FIG.
In step S10, the image processing unit 11 determines whether or not the lane marking is detected. When the lane marking is detected (step S10: Y), the process proceeds to step S11. When the lane marking is not detected (step S10: N), the process proceeds to step S14.
In step S11, the vehicle state setting unit 12 determines whether a preceding vehicle has been detected. When a preceding vehicle is detected (step S11: Y), the process proceeds to step S12. If the preceding vehicle is not detected (step S11: N), the process proceeds to step S13.

In step S12, the vehicle state setting unit 12, the turning control unit 14, and the reaction force control unit 15 perform a first control calculation process.
Please refer to FIG. In step S20, the first lateral position deviation calculating unit 70 of the first deviation calculating unit 12d calculates the lateral position deviation Dv1 between the vehicle and the preceding vehicle.
In step S21, the second lateral position deviation calculating unit 71 calculates a lateral position deviation Dr between the reference traveling trajectory and the vehicle.

In step S22, the following distance calculation unit 72 calculates the following distance D between the vehicle and the preceding vehicle.
In step S23, the mixture ratio determining unit 73 determines the mixture ratio K of the lateral position deviation Dv1 according to the inter-vehicle distance D shown in FIG. Multipliers 74 and 76 calculate K × lateral position deviation Dv1 and (1−K) × lateral position deviation Dr, and adder 77 calculates mixed lateral position deviation Dc = (K × lateral position deviation Dv1) + ( (1−K) × lateral position deviation Dr) is calculated.

In step S24, the second deviation calculator 12e calculates the lateral position deviation Dv2 between the vehicle and the vehicle.
In step S25, the curvature calculation unit 12c calculates the road curvature Rr of the road white line at the scheduled arrival position.
In step S26, the turning control unit 14 calculates an LK command turning angle based on the mixed lateral position deviation Dc between the vehicle and the preceding vehicle. The turning control unit 14 calculates a basic command turning angle calculated based on the steering angle and the steering angular velocity. The turning control unit 14 calculates a turning angle command value by adding the LK command turning angle to the basic command turning angle.

In step S27, the reaction torque correction value calculation unit 64 of the reaction control unit 15 calculates a reaction torque correction value based on the lateral position deviation Dv2.
In step S28, the offset amount calculation unit 61 of the reaction force control unit 15 calculates an axial force offset amount based on the road curvature Rr.
The process in step S29 is the same as the process in step S7 in FIG.

Please refer to FIG. Thereafter, the process proceeds to step S17.
In step S13, the vehicle state setting unit 12, the turning control unit 14, and the reaction force control unit 15 perform a second control calculation process.
Referring to FIG. In step S30, the first deviation calculation unit 12d and the second deviation calculation unit 12e of the vehicle state setting unit 12 calculate a lateral position deviation Dr between the reference traveling trajectory and the vehicle.
In step S31, the curvature calculation unit 12c calculates the road curvature Rr of the road white line at the scheduled arrival position.

In step S32, the turning control unit 14 calculates an LK command turning angle based on the lateral position deviation Dr. The turning control unit 14 calculates a basic command turning angle calculated based on the steering angle and the steering angular velocity. The turning control unit 14 calculates a turning angle command value by adding the LK command turning angle to the basic command turning angle.
In step S33, the reaction torque correction value calculator 64 of the reaction controller 15 calculates a reaction torque correction value based on the lateral position deviation Dr.
In step S34, the offset amount calculation unit 61 of the reaction force control unit 15 calculates the axial force offset amount based on the road curvature Rr.
The processing in step S35 is the same as the processing in step S7 in FIG.

Please refer to FIG. Thereafter, the process proceeds to step S17.
In step S14, the vehicle state setting unit 12 determines whether a preceding vehicle has been detected. If a preceding vehicle is detected (step S14: Y), the process proceeds to step S15. When the preceding vehicle is not detected (Step S14: N), the process proceeds to Step S16.
In step S15, the vehicle state setting unit 12, the turning control unit 14, and the reaction force control unit 15 perform a third control calculation process.

Referring to FIG. The processing in steps S40 to S46 is the same as the processing in steps S1 to S7 in FIG.
Please refer to FIG. Thereafter, the process proceeds to step S17.
In step S16, the control state setting unit 13 sets the LK support control flag to off. As a result, the turning control unit 14 and the reaction force control unit 15 calculate the turning angle command value and the command steering reaction force torque without performing the LK support control. Thereafter, the processing proceeds to step S17.
The processing in step S17 is the same as the processing in step S18 in FIG.

(Effect of Second Embodiment)
(1) A lateral position deviation Dr between a reference traveling path and the vehicle is detected. The turning control unit 14 controls the turning angle of the steered wheels so that the lateral position deviation Dr decreases. The inter-vehicle distance calculation unit 72 detects an interval between the preceding vehicle and the vehicle. When the distance between the preceding vehicle and the vehicle is longer than when the distance between the preceding vehicle and the vehicle is short, the first deviation calculating unit 12d determines the amount of turning by the turning control according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle. And the amount of turning by turning control according to the lateral position deviation Dr is increased. That is, as the distance between the preceding vehicle and the vehicle increases, the amount of steering by the steering control according to the lateral position deviation Dv1 decreases, and the steering by the steering control according to the lateral position deviation Dr. Increase the amount.
For example, the first deviation calculating unit 12d calculates the product obtained by multiplying the lateral position deviation Dr by a coefficient (1-K) that increases as the inter-vehicle distance D increases and the inter-vehicle distance D increases. A mixed lateral position deviation Dc, which is a sum of products obtained by multiplying the decreasing coefficient K by the lateral position deviation Dv1, is calculated. The turning control unit 14 controls the turning amount of the steered wheels according to the mixed lateral position deviation Dc.

  If the distance between the preceding vehicle and the vehicle is long as compared with the case where the distance between the preceding vehicle is short, the measurement accuracy of the lateral position deviation from the preceding vehicle is relatively reduced. On the other hand, since the traveling lane dividing line is less likely to be blocked by the preceding vehicle, the measurement accuracy of the lateral position deviation Dr between the vehicle and the reference traveling trajectory set on the traveling lane is improved. Therefore, when the distance between the preceding vehicle and the vehicle is long, by increasing the steering amount by the steering control according to the lateral position deviation Dr between the reference traveling trajectory and the vehicle, the lateral accuracy with higher measurement accuracy can be improved. The steering control can be performed according to the position deviation.

  Conversely, when the interval between the preceding vehicle and the vehicle is short, the accuracy of measuring the lateral position deviation from the preceding vehicle is improved when the interval is short. On the other hand, since the lane marking is easily blocked by the preceding vehicle, the measurement accuracy of the lateral position deviation Dr between the reference traveling trajectory and the vehicle is relatively reduced. Therefore, when the distance between the preceding vehicle and the vehicle is short, by increasing the steering amount by the steering control according to the lateral position deviation Dv1 between the vehicle and the preceding vehicle, the lateral position with higher measurement accuracy can be improved. Steering control can be performed according to the deviation.

(2) The image processing unit 11 determines whether or not the road curvature Rr of the traveling road of the vehicle can be detected. If the road curvature Rr cannot be detected, the reaction force control unit 15 controls the steering reaction force that prompts the vehicle to follow the preceding vehicle based on the turning angle of the steered wheels and the turning curvature Rv of the preceding vehicle. Add to wheel 1a. If the road curvature Rr can be detected, a steering reaction force that encourages the vehicle to travel along the traveling lane is applied to the steering wheel 1a based on the steered angle of the steered wheels and the road curvature Rr.
Thus, when the road curvature Rr can be detected, the steering reaction force is controlled according to the road curvature Rr of the traveling lane that does not change with time, so that the steering wheel 1a can perform a calm operation. On the other hand, even if the road curvature Rr cannot be detected, it is possible to apply a steering reaction force to the steering wheel 1a that prompts the driver to turn following the preceding vehicle.

  DESCRIPTION OF SYMBOLS 1 ... Steering part, 1a ... Steering wheel, 1b ... Column shaft, 1c ... Steering torque sensor, 1d ... Reaction force motor, 1e ... Reaction force motor drive circuit, 1f ... Steering angle sensor, 1g ... Current sensor, 2 ... Steering , 2a ... pinion shaft, 2b ... steering gear, 2c ... steering motor, 2d ... steering motor drive circuit, 2e ... steering angle sensor, 2f ... rack gear, 2g ... steering rack, 3 ... backup clutch, 4 ... SBW Controller, 5FL: Left front wheel, 5FR: Right front wheel, 6: External recognition sensor, 7: Vehicle speed sensor, 11: Image processing unit, 12: Vehicle state setting unit, 12a: Gain calculation unit, 12b: Travel locus calculation unit, 12c ··· Curvature calculation unit, 12d ··· first deviation calculation unit, 12e ··· second deviation calculation unit, 12f ··· steering determination unit, 13 ··· control state setting unit, 14 ··· steering control Unit, 15: reaction force control unit, 20: gain multiplication unit, 21: steering angular velocity calculation unit, 22: differential steer gain multiplication unit, 23: LK command steering angle calculation unit, 24: multiplier, 25: adder, Reference numeral 40: repulsive force calculator, 40a: gain multiplier, 40b: multiplier, 43: target yaw moment calculator, 44: target yaw acceleration calculator, 45: target yaw rate calculator, 46: command steering angle calculator, 47: Limiter processing unit, 60: Rack axial force calculation unit, 61: Offset amount calculation unit, 61a: Upper and lower limit limiter, 61b: SAT gain calculation unit, 61c: Multiplier, 61d: Limiter processing unit, 62: Subtractor, 63: target reaction torque calculation unit, 64: reaction torque correction value calculation unit, 64a: reaction force calculation unit, 64b: multiplier, 64c: limiter processing unit, 64d: lateral position deviation-reaction force map, 65: addition vessel, 0: first lateral position deviation calculating section, 71: second lateral position deviation calculating section, 72: inter-vehicle distance calculating section, 73: mixture ratio determining section, 74: multiplier, 75: subtractor, 76: multiplier, 77 … Adder

Claims (6)

A driving support method for a vehicle including a steer-by-wire steering mechanism,
The steered wheels are steered according to the steering operation of the steering wheel,
Controlling the steering reaction force according to the steering operation of the steering wheel or the steering angle of the steered wheels,
Detecting a first deviation between the lateral position of the preceding vehicle and the lateral position of the vehicle,
Executing a first steering control for controlling a steering angle of the steered wheels so that the first deviation decreases;
Detecting the turning curvature of the preceding vehicle,
Applying the first steering reaction force to the steering wheel that prompts the vehicle to follow the preceding vehicle based on the turning curvature when performing the first steering control;
A driving support method characterized by the above-mentioned. Detecting a second deviation between the reference traveling trajectory set in the traveling lane and the lateral position of the vehicle,
Executing a second steering control for controlling a steering angle of the steered wheels such that the second deviation decreases;
Detecting an inter-vehicle distance between the preceding vehicle and the vehicle,
As the inter-vehicle distance increases, the amount of steering of the steered wheels by the first steering control decreases, and the amount of steering of the steered wheels by the second steering control increases.
The driving support method according to claim 1, wherein:   The sum of a product obtained by multiplying the second deviation by a coefficient that increases as the inter-vehicle distance increases and a product obtained by multiplying the first deviation by a coefficient that decreases as the inter-vehicle distance increases. The driving support method according to claim 2, wherein the steering amount of the steered wheels is controlled accordingly. Determine whether the road curvature of the traveling lane of the vehicle can be detected,
When the road curvature cannot be detected, the first steering reaction force is applied to the steering wheel based on the steering angle and the turning curvature,
When the road curvature can be detected, a second steering reaction force that prompts the vehicle to travel along the travel lane based on the turning angle and the road curvature is applied to the steering wheel.
The driving support method according to any one of claims 1 to 3, wherein: Detecting one of the steering angle of the steering wheel and the steering angle,
Estimating the steering rack axial force applied to the steering rack of the vehicle according to the steering angle and the steering angle,
Offset the estimated steering rack axial force according to the turning curvature,
Applying the first steering reaction force to the steering wheel by applying a steering reaction force corresponding to the offset steering rack axial force to the steering;
The driving support method according to any one of claims 1 to 4, wherein: A driving assistance device for a vehicle including a steer-by-wire steering mechanism,
A sensor for detecting a lateral position of a preceding vehicle of the vehicle,
Steering a steered wheel according to a steering operation of a steering wheel, controlling a steering reaction force according to a steering operation of the steering wheel or a steering angle of the steered wheel, and setting a lateral position of the vehicle and the preceding vehicle Executing a first turning control for controlling a turning angle of the steered wheels so as to reduce a first deviation from the lateral position of the vehicle, detecting a turning curvature of the preceding vehicle, and executing the first turning control. When executing, a controller that applies a steering reaction force to the steering wheel that encourages the vehicle to turn to follow the preceding vehicle based on the turning curvature.
A driving assistance device comprising:

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