JP2020157901A - Steering assist device - Google Patents

Abstract

To reduce discomfort with respect to steering by a driver, in a case where there is steering input by the driver during travel in automatic operation.SOLUTION: Based on peripheral information and map information, own vehicle position correction torque is calculated such that the vehicle is located close to a preset target runway. During automatic operation control for controlling a power steering device according to the own vehicle position correction torque, if there is steering input by a vehicle's driver, another vehicle traveling in an adjacent traffic lane is detected, and the direction of steering torque by the driver's steering input and the direction of the own vehicle position correction torque are the same, the own vehicle position correction torque is reduced.SELECTED DRAWING: Figure 6

Description

The present invention relates to a steering assist device that assists steering of a vehicle.

In recent years, various technologies related to steering assist control have been proposed to assist and assist steering so that the vehicle travels along a set target track. Patent Document 1 discloses a steering assist device for a steer-by-wire vehicle. The steering assist device executes lane keep control that assists steering so that the vehicle travels based on a set target course. More specifically, in this lane keep control, a feedback control amount based on the traveling state of the vehicle and a feedback control amount based on the traveling path shape are calculated. Then, when the driver inputs steering during lane keep control, which feedback control amount is used is selected based on the steering torque by the driver's steering, and the steering torque to the steering motor is applied using the selected feedback control amount. It is calculated and the steering torque is controlled.

JP-A-2014-234111 JP-A-2009-205358

When there is a driver's steering input (hereinafter referred to as "override") while driving in automatic driving, the steering torque due to automatic driving interferes with the steering torque due to the driver's steering input, and as a result, the driver cuts out the steering wheel. You may feel a sense of discomfort, such as a feeling of sticking to the time or a feeling of steering when turning back.

Then, when the driver needs to pay particular attention to steering and is in a situation where tension is required, for example, in a situation where another vehicle is traveling in an adjacent lane, when the driver overrides the steering, the driver steers. It is not preferable that a feeling of strangeness such as the above occurs because it causes discomfort or anxiety about steering. In this respect, the control of Patent Document 1 may still cause a sense of discomfort such as a feeling of steering, and there remains room for improvement.

One object of the present invention is to provide a technique capable of performing steering assist control so as to reduce a sense of discomfort for the driver's steering when there is a steering input by the driver during traveling in automatic driving. There is.

In one aspect of the present invention, a steering assist device mounted on a vehicle is provided. The steering assist device includes a power steering device for steering the wheels of the vehicle and a control device. The control device includes another vehicle detection unit and an automatic driving control unit. The other vehicle detection unit acquires the surrounding information of the vehicle and the map information, and detects another vehicle traveling in the adjacent lane of the vehicle. Based on the surrounding information and map information, the autonomous driving control unit calculates the vehicle position correction torque so that the vehicle approaches the preset target track, and sets the power steering device according to the vehicle position correction torque. Execute automatic operation control to be controlled.

Further, the automatic driving control unit has a steering input by the driver of the vehicle during execution of the automatic driving control, detects another vehicle traveling in the adjacent lane, and determines the direction of the steering torque by the steering input of the driver. When the direction of the own vehicle position correction torque is the same, the own vehicle position correction torque is reduced.

According to the present invention, when another vehicle traveling in the adjacent lane of the vehicle is detected, the own vehicle position correction torque input by the automatic driving control is reduced. As a result, it is possible to reduce the discomfort of the steering operation that the driver feels when the driver inputs the steering during the automatic driving control.

It is a conceptual diagram for demonstrating an example of the situation which the driver input steering during the target track follow-up control. It is a schematic diagram for demonstrating the structure of the steering assist device mounted on the vehicle which concerns on this Embodiment of this invention. It is a flowchart which shows the processing example by the control device which concerns on embodiment of this invention. It is a figure which shows the example of the case which corresponds to the situation which wants to prevent the steering wheel slipping feeling in the embodiment of this invention. In the embodiment of the present invention, it is a figure for demonstrating the switching of the driver cooperation sensitivity when it is determined that it is the situation which wants to loosen the own vehicle position correction of steering assist control. In the embodiment of the present invention, it is a timing chart for explaining the switching of the driver cooperation sensitivity when it is determined that the situation is such that the steering wheel steering feeling is to be prevented.

Embodiments of the present invention will be described with reference to the accompanying drawings.

1. 1. Outline The vehicle 1 according to the present embodiment has a steering assist function that assists the steering of the vehicle 1. For example, the steering assist function includes general EPS (Electric Power Steering) control.

Further, the steering assist function according to the present embodiment also includes automatic steering in which the vehicle 1 is steered so as to follow the target track. The steering assist control that assists the steering of the vehicle 1 so as to follow the target track is hereinafter referred to as "target track tracking control". The target track is typically calculated by an automated driving system mounted on the vehicle 1. For the sake of simplification of the description, the steering torque due to the steering input of the driver will also be referred to as "driver torque", and the steering torque given by steering assist control will also be referred to as "own vehicle position correction torque".

By the way, when the driver performs steering input (hereinafter, also referred to as "override") during the target track tracking control, the driver torque and the vehicle position correction torque may interfere with each other. When the driver torque and the vehicle position correction torque work in opposite directions, the driver feels the steering wheel operation heavy, and when the driver torque works in the same direction, the steering wheel operation feels light. Then, depending on the timing at which the torques are in the same direction, the driver may feel that the steering is off.

FIG. 1 is a conceptual diagram for explaining an example of a situation in which the driver inputs steering input during target track tracking control. In the situation shown in FIG. 1, at the timing a, the driver of the vehicle 1 has started to cut the steering wheel. On the other hand, in the sections a to c, the automatic driving system outputs the own vehicle position correction torque so as to return the vehicle 1 to the center of the lane. Therefore, in the sections a to b, the own vehicle position correction torque becomes a reaction force with respect to the steering of the driver. On the other hand, in the sections b to c, the driver torque decreases, while the vehicle position correction torque increases. In the sections c to e, the vehicle position correction torque and the driver torque are in the same direction, and the vehicle 1 is returned to the lane center (target runway) direction.

Then, under the situation where the driver overrides, when the driver torque decreases while the vehicle position correction torque in the reverse direction increases, the driver feels the steering wheel operation heavy. In addition, when the directions of the driver torque and the vehicle position correction torque are the same, in the region where the driver torque is small, the steering wheel returns more than the driver's image, and the steering angle of the steering wheel with respect to the driver torque becomes large, and depending on the timing, the driver May feel a sense of steering.

In the automatic driving control of the present embodiment, the following steering assist control is performed in order to eliminate the discomfort of the steering wheel operation at the time of overriding by the driver. Hereinafter, the steering assist control according to the present embodiment will be described in more detail.

2. 2. Steering Assist Device FIG. 2 is a schematic diagram for explaining the configuration of the steering assist device mounted on the vehicle 1 according to the present embodiment.

Although not shown, the vehicle 1 includes a steering wheel (steering wheel), a steering shaft, pinion gears, a rack bar, and wheels. The steering wheel is an operating member used by the driver to perform a steering operation. One end of the steering shaft is connected to the steering wheel and the other end is connected to the pinion gear. The pinion gear meshes with the rack bar. Both ends of the rack bar are connected to the left and right wheels via tie rods. The rotation of the steering wheel is transmitted to the pinion gear via the steering shaft. The rotational motion of the pinion gear is converted into the linear motion of the rack bar, which changes the steering angle of the wheels.

The steering assist device 2 is mounted on the vehicle 1 and assists the steering (wheel steering) of the vehicle 1. The steering assist device 2 includes an EPS device, a steering angle sensor, a steering torque sensor, a touch sensor, a driving environment information acquisition device, and a control device 10.

The EPS device is a power steering device that mechanically steers the wheels. More specifically, the EPS device includes an electric motor, and the rotation of the electric motor generates an assist torque. For example, the electric motor is connected to the rack bar via a conversion mechanism. When the rotor of the electric motor rotates, the conversion mechanism converts the rotational motion into the linear motion of the rack bar. In this way, the assist torque is generated and the steering of the wheels is assisted.

The steering angle sensor detects the steering angle of the steering wheel. The steering torque sensor detects the driver torque, which is the steering torque applied to the steering shaft. Detection information indicating the steering angle and steering torque is input to the control device 10.

The touch sensor detects information related to steering by the driver of the vehicle 1 as steering operation information. The steering operation information detected by the touch sensor is input to the control device 10.

The driving environment information acquisition device acquires driving environment information indicating the driving environment of the vehicle 1 necessary for carrying out steering assist control in automatic driving including target track tracking control. The driving environment information includes position information indicating the position of the vehicle 1, map information, surrounding condition information indicating the surrounding condition of the vehicle 1, vehicle condition information indicating the condition of the vehicle 1, and the like. The position information can be obtained by using, for example, GPS (Global Positioning System). Map information is obtained from the map database. Surrounding condition information can be obtained by using external sensors such as cameras, riders, and radars. For example, the surrounding situation information includes information on surrounding vehicles. The vehicle state information is obtained based on the detection results of various sensors mounted on the vehicle 1. For example, the vehicle state information includes information on the speed, yaw rate, and winker state of the vehicle 1.

The control device 10 is a microcomputer including a processor, a storage device, and an input / output interface. The control device 10 is also called an ECU (Electronic Control Unit). The control device 10 receives various information through the input / output interface. Then, the control device 10 controls the operation of the vehicle 1 based on the received information. In particular, in the present embodiment, the control device 10 performs steering assist control by controlling the operation of the EPS device.

More specifically, the control device 10 includes an automatic operation target generation unit 100 and an EPS assist calculation unit 200 as functional blocks. The automatic driving target generation unit 100 further includes a target track generation unit 102 and a vehicle position correction calculation unit 104. The own vehicle position correction calculation unit 104 further includes a driver cooperation sensitivity adjustment unit 106. These functional blocks are realized by the processor of the control device 10 executing the control program stored in the storage device. The control program may be stored on a computer-readable recording medium.

3. 3. Steering Assist Control The EPS Assist Calculation Unit 200 performs general EPS control. More specifically, the EPS assist calculation unit 200 calculates the assist control amount for controlling the operation of the EPS device based on the input steering angle and steering torque (driver torque) detection information. The EPS assist calculation unit 200 outputs the assist control amount to the EPS device. The EPS device drives the electric motor according to the assist control amount to generate the assist torque.

The automatic driving target generation unit 100 generates a travel plan in the target track tracking control for automatic driving, and determines a control target value in the target track tracking control of the vehicle 1 based on the travel plan. Specifically, the target track generation unit 102 calculates the target track of the vehicle 1 based on the driving environment information acquired by the driving environment information acquisition device, and steers the torque so that the vehicle 1 travels along the target track. The feed forward control term (FF term) of is calculated.

The own vehicle position correction calculation unit 104 detects the deviation between the vehicle 1 and the target runway, and calculates a feedback control term (FB term) for correcting the position of the vehicle 1 accordingly.

The automatic driving target generation unit 100 determines the control amount of the EPS device from the FF term and the FB term, and controls the EPS device based on the control amount, so that the vehicle 1 travels following the target runway.

Further, the driver cooperation sensitivity adjusting unit 106 of the own vehicle position correction calculation unit 104 corrects the FB term calculated by the own vehicle position correction calculation unit 104 according to the input information such as the traveling scene and the steering operation information. As a result, the cooperative sensitivity to the driver's steering wheel operation in automatic driving can be switched.

For example, when there is a steering input of the driver during the target track tracking control, the control device 10 includes an FB term corrected by the driver coordination sensitivity adjusting unit 106 and an FF term calculated by the target track generation unit 102. The control amount of the EPS device is determined from the assist torque calculated by the EPS assist calculation unit 200, and is output to the EPS device. The EPS device drives the electric motor according to this control amount to generate steering torque.

Here, the control in the driver cooperation sensitivity adjusting unit 106 will be described. FIG. 3 is a flowchart showing a control routine in the driver cooperation sensitivity adjusting unit 106. In the routine shown in FIG. 3, first, in step S2, it is determined whether or not overriding is currently in progress. That is, it is determined whether or not the steering input is made by the driver during the target track tracking control.

If it is determined in step S2 that the override is not in progress, the current process ends as it is.
On the other hand, if it is determined in step S2 that the override is in progress, then the situation is determined. Here, it is a situation in which the vehicle position correction in the steering assist control is desired to be relaxed (hereinafter referred to as "first situation"), or a situation in which it is desired to prevent a feeling of steering slippage (hereinafter referred to as "second situation"). Is determined.

The first situation corresponds to the following (1) and corresponds to any one or more of (2) to (4).
(1) The driver's steering operation is in the direction of approaching the target track in the target track tracking control (2) The timing is close to the timing of passing the oncoming vehicle (3) There are parallel vehicles (4) Other than the national expressway or the motorway Running

However, even if it corresponds to the above first situation, if it further corresponds to the following (5), it shall correspond to the second situation.
(5) The differential value of the driver torque generated by the steering wheel operation by the driver and the own vehicle position correction target angle have the same sign.

That is, when the above (1) and (5) are applicable and any of (2) to (4) is applicable, it is determined that the situation corresponds to the second situation, not the first situation.

The determination as to whether or not any of the above (2) to (4) is applicable is performed based on the traveling scene. The driving scene can be acquired from the driving environment information obtained from GPS, a camera, a map database, or the like. Further, whether or not the above (1) is applicable is determined based on the steering operation information input to the control device 10.

FIG. 4 shows an example of the second situation. In the example shown in FIG. 4, the differential value (broken line (b)) of the driver torque (solid line (a) in FIG. 4) generated by the steering wheel operation of the driver in the sections t1 to t2 and the vehicle position correction in the steering assist control. The target angle (solid line (c)) has the same code. In other words, the section t1 to section t2, which is the second situation, is a section from the time when the driver turns the steering wheel to turn back steering and the steering angle returns to the neutral point.

In the second situation, the vehicle position correction target angle at the time when the differential value of the driver torque and the vehicle position correction angle in the steering assist control have the same sign is set as the "reference correction angle" and is used in the processing described later. ..

When the situation determination in step S4 determines that the situation is the first, in step S6, the driver coordination sensitivity is switched to the coordination sensitivity that slows down the vehicle position correction.

FIG. 5 is a diagram for explaining switching of the driver cooperation sensitivity when it is determined to be the first situation. When it is determined to be the first situation, as shown by the arrow in FIG. 5, the time required to close the lateral displacement deviation from the target track is longer than the time set in the normal steering assist control. Try to be long. That is, the own vehicle position correction torque is adjusted so that the steering cycle of the own vehicle position correction is longer than that of the driver operation.

FIG. 6 is a timing chart for explaining the process of switching the driver cooperation sensitivity when it is determined to be the second situation. As described above, when it is determined in the second situation in step S4, the own vehicle position correction target angle at the time t1 is set as the reference correction angle. Then, during the period satisfying the condition of the second situation (between time points t1 and t2), the own vehicle position correction torque in the steering assist control is limited to the own vehicle position correction torque when the reference correction angle is set (time point t1). .. That is, during this period, when the own vehicle position correction target angle exceeds the reference correction angle, the own vehicle position correction torque by steering assist control is taken as the own vehicle position correction torque when the reference correction angle is set.

After that, at the time point t2 in which the driver torque increases again in the turning back direction, the own vehicle position correction torque is set as the upper limit of the own vehicle position correction torque gradient immediately before reaching the time point t1. Is given. That is, the vehicle position correction torque is obtained from t2 when the steering angle returns to the neutral point by performing turn-back steering after turning-steering by the driver and until t3 when turning back in the turning-steering direction is started again. The gradient of is limited to the gradient of the own vehicle position correction torque immediately before reaching the time point t1.

After the cooperative sensitivity switching process in step S6, this process ends.

As described above, according to the present embodiment, when the applicable conditions of the first or second situation are satisfied, the vehicle position correction is relaxed. That is, the sensitivity to the steering operation of the driver is set to be high. As a result, it is possible to reduce the discomfort of the steering wheel operation when the driver overrides the steering assist control.

In the present embodiment, the above conditions (1) to (5) have been exemplified as situations in which the vehicle position correction is desired to be relaxed or the feeling of steering is prevented, but these conditions should be set as appropriate. However, it is not limited to the above (1) to (5).

In addition, there are two situations, one in which you want to loosen the position correction of your vehicle and the other in which you want to prevent the feeling of steering, but only the situation in which you want to loosen the position correction of your vehicle is set. Control may be performed to loosen the position correction.

1 Vehicle 2 Steering assist device 10 Control device 100 Automatic driving target generation unit 102 Target track generation unit 104 Own vehicle position correction calculation unit 106 Driver cooperation sensitivity adjustment unit 200 EPS assist calculation unit

Claims (1)

It is equipped with a power steering device that steers the wheels of the vehicle and a control device.
The control device is
Another vehicle detection unit that acquires other vehicle surrounding information and map information of the vehicle and detects another vehicle traveling in the adjacent lane of the vehicle.
Based on the surrounding information and the map information, the vehicle position correction torque is calculated so as to bring the vehicle closer to the preset target track, and the power steering device is controlled according to the vehicle position correction torque. An automatic operation control unit that executes operation control and
With
The automatic operation control unit
During the execution of the automatic driving control, there is a steering input by the driver of the vehicle, another vehicle traveling in the adjacent lane is detected, and the direction of the steering torque by the steering input of the driver and the position of the own vehicle. When the direction of the correction torque is the same, the vehicle position correction torque is reduced.
A steering assist device characterized in that it is configured as such.

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