JPH06336169A - Control method for automatic steering device - Google Patents

Abstract

PURPOSE:To accurately steer a vehicle in the case of the quick steering for avoiding a collision or the like in automatic steering control. CONSTITUTION:A gear ratio changing mechanism 25 having a steering control motor 36 and a torque control motor 38 is provided on the steering device 10 of a vehicle 1. In the automatic steering mode, the steering control motor 36 is rotatively controlled, the torque control motor 38 is torque-controlled, and the vehicle 1 is automatically steered along the white line or the like on a road with a steering wheel kept intact. For quick steering in the automatic steering mode, both the steering control motor 36 and the torque control motor 38 are controlled, the vehicle 1 is automatically steered by them, the vehicle 1 is accurately steered while the load of the steering control motor 36 is reduced, and a collision with an obstacle is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an automatic steering device which is used in a driving assistance system (ADA) of a vehicle such as an automobile and automatically electronically steers the vehicle. The present invention relates to automatic steering control when performing.

[0002]

2. Description of the Related Art In recent years, as a measure to drastically improve the safety of a vehicle, a technique for avoiding a collision against a collision damage reducing technique such as an airbag, that is, a driving operation system is actively assisted for safety. A comprehensive Active Drive Assist system (ADA) that automatically controls the side has been developed. This ADA system has cameras mounted in front of and behind the vehicle to recognize a road condition, another vehicle, and an external environment such as an obstacle three-dimensionally by a control unit.
The driver is provided with the same autonomous running capability as the driver, and the autonomous running capability is configured to automatically and properly operate various devices in the operation system such as the brake, throttle, and steering. Then, as functions aimed at by the ADA system, a collision prevention function and a limited automatic traveling function are considered. The collision prevention function is to automatically brake when there is a risk of a rear-end collision due to an error in driving operation or to correct the steering wheel in case of cross wind. The limited automatic traveling function is to perform automatic steering on behalf of the driver for lane following traveling, avoid obstacles automatically, and maintain a safe inter-vehicle distance.

The above ADA system will be described more specifically. For example, Japanese Patent Application No. 4-653 filed by the present applicant.
As shown in the application No. 47, the front scene and traffic environment are captured by a plurality of cameras mounted on the vehicle, the image is divided into small areas, and the distance is calculated by triangulation for each, and the entire screen is cubic. Obtain an image of the original distance distribution. Then, lanes, vehicles in front, obstacles, etc. are separated and detected from the distance image. Left and right white lines, road shapes, etc. are recognized from the lane. For a forward vehicle or an obstacle, what kind of object the object is, the relative distance to the obstacle, the speed, and the like are recognized to obtain various image data.

As a system for automatically steering using the above-mentioned image data, as shown in the application of Japanese Patent Laid-Open No. 3-238809, a planetary gear type system having a steering control motor and a torque control motor in a steering system of a steering device is used. A gear ratio variable mechanism is provided. Then, the steering angle along the white lane of the lane is calculated from the image data, etc., and a current corresponding to this steering angle is supplied to the steering control motor to operate the gear ratio variable mechanism to automatically steer the tire side. However, it is considered that the vehicle autonomously follows the lane. This system has been made more concrete by the development of the most important image recognition technology, and it is necessary to further develop the technology in various points in order to put it into practical use.

Conventionally, as for the above-mentioned automatic steering device, for example, there is a prior art disclosed in Japanese Patent Laid-Open No. 3-276310. In this prior art, an unmanned moving vehicle is targeted, a predicted position and a target position of the own vehicle after a predetermined time are set, and a control amount is calculated from a deviation between the two. It is also shown that traveling control is performed by correcting the control amount based on the distance between the current vehicle position and the predicted position and outputting the corrected amount to the actuator.

[0006]

By the way, in the above-mentioned prior art, traveling control is performed by outputting a signal of a control amount due to a deviation between the predicted position of the vehicle and the target position to a single actuator such as a motor. However, there are the following problems. That is, when traveling on an actual road adapted to a vehicle such as a passenger car, an obstacle may exist in front of the vehicle. In this case, steer the steered vehicle to avoid a collision with the obstacle. Controlled by. In such a situation, when a single actuator such as a motor is used as in the prior art, the load on the motor increases and a high output motor is required. Also, due to insufficient rudder force, it may not be possible to accurately steer.

SUMMARY OF THE INVENTION In view of the above points, the present invention has an object to appropriately steer in the case of sudden turning such as collision avoidance in automatic steering control.

[0008]

To achieve this object, the present invention is directed to a vehicle steering system provided with a steering control motor and a torque control motor for providing a variable gear ratio mechanism for automatic steering. In the case of, the steering control motor is rotationally controlled by the image data in front of the vehicle, the vehicle speed, and the signal of the actual steering angle, and the torque control motor is torque-controlled so that the running vehicle follows the white line of the road without operating the steering wheel. In the automatic steering device that automatically steers the vehicle, it is determined whether the steering angle speed of the actual steering angle is larger than the set value in the automatic steering mode. It is characterized in that the rotation is controlled in the same turning direction in conjunction with the steering control motor.

[0009]

In the present invention based on the above control method, when the automatic steering mode is set while the vehicle is traveling, image data in front of the vehicle,
The commanded steering angle is calculated based on the relationship between the vehicle white line and the vehicle, for example, the relationship between the white line on the road and the vehicle, and the steering control motor of the gear ratio variable mechanism rotates in accordance with this commanded steering angle. Torque assist is provided to cancel the steering torque. Therefore, even if the driver does not operate the steering wheel, the front wheels automatically steer and safely follow the lane along the white line. In the automatic steering mode, the steering state is further determined by the steering angle speed of the actual steering angle, and in order to avoid a collision with an obstacle, when the steered steering speed is increased and steered steered, the torque control motor is also steered. The rotation is controlled in the direction. Therefore, both the steering control motor and the torque control motor are automatically steered to increase the steering force and the like, and the steering control motor is appropriately steered while avoiding a collision while reducing the load on the steering control motor.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. An outline of the ADA system will be described with reference to FIG. First, the throttle valve 3 of the engine 2 of the vehicle 1 is provided with an actuator 11 that opens and closes by an electric signal,
An automatic brake hydraulic unit 12 that increases or decreases the brake pressure by an electric signal is provided in a brake device 8 that applies brake pressure to the wheel cylinders 7 of the front wheels 5 and the rear wheels 6 by operating the brake pedal 4 to perform braking. A CCD camera 13 for picking up a predetermined range in front of the vehicle 1 is arranged on the left and right sides of the vehicle 1, and an automatic steering power unit 1 for steering an electric signal to a steering device 10 having a steering wheel 9 is provided.
4 are provided.

As a control system, an image recognition control unit 15 to which the image pickup signal of the CCD camera 13 is input is provided, and the distance is calculated by the triangulation method based on the image pickup signal, and an image with a three-dimensional distance distribution is displayed on the entire screen. obtain. Then, lanes, vehicles in front, obstacles, etc. are separately detected from the distance image, and left and right white lines, road shapes, etc. are recognized from the lanes. For a forward vehicle or an obstacle, what kind of object the object is, the relative distance to the obstacle, the speed, and the like are recognized to obtain various image data. This image data is input to the inter-vehicle distance control unit 16 and the automatic steering control unit 17.

The inter-vehicle distance control unit 16 calculates the acceleration / deceleration so as to maintain a safe distance with respect to the preceding vehicle and obstacles on the road based on the image data and various other sensor signals, and an appropriate acceleration / deceleration based on this acceleration / deceleration is calculated. A throttle signal indicating the throttle opening is output to the actuator 11 for throttle control. Further, a brake signal having an appropriate brake pressure based on the acceleration / deceleration is output to the automatic brake hydraulic unit 12 for brake control. Even if the driver's brake operation is not sufficient, it is possible to keep a safe distance and to drive safely. The automatic steering control unit 17 calculates the deviation between the white line on the road and the vehicle based on the image data and various other sensor signals, and outputs a steering signal based on this deviation to the automatic steering power unit 14 to perform steering control. Even if the driver does not operate the steering wheel, it is possible to safely follow the lane.

In FIG. 3, the automatic steering power unit 14
The configuration of will be described. First, the steering device 10
The steering shaft 20 is divided into an input shaft 21 and an output shaft 22, a handle 9 is provided at the end of the input shaft 21, and the output shaft 22 is connected to the front wheels 5 via a hydraulic power steering mechanism 23. The variable gear ratio mechanism 25 is connected between 21 and 22 by bypass. Gear ratio variable mechanism 25
Is constituted by combining two sets of gears 26 and 27 and one set of planetary gear 30 with the input and output shafts 21 and 22 and the motor shaft 24 arranged in parallel therewith.

That is, in the first gear 26, a small-diameter drive gear 26a is integrally connected to the input shaft 21, and a large-diameter driven gear 26b is rotatably provided on the motor shaft 24. In the second gear 27, the large-diameter drive gear 27a is the motor shaft 2
4, the driven gear 27b having a small diameter is integrally coupled to the output shaft 22. In the planetary gear 30, the sun gear 31 is integrally coupled to the motor shaft 24, the ring gear 32 is formed inside the drive gear 27 a of the second gear 27, and the pinion 33 that meshes with the sun gear 31 and the ring gear 32 is the driven gear of the first gear 26. It is supported by a carrier 34 integral with 26b. A steering control motor 36 is connected to one end of the motor shaft 24 via a reversibly rotatable worm gear 35, and a torque control motor 38 is connected to the input shaft 21 via a similar worm gear 37. Further, between the input shaft 21 and the output shaft 22, there is provided a stopper 39 which is directly connected when the tire collides with a curb or the like and a large steering torque is input and both shafts 21 and 22 rotate by a predetermined angle or more.

When the driver steers the handle 9 while the sun gear 31 of the motor shaft 24 is fixed, the carrier 34 of the planetary gear 30 is rotated by the input shaft 21 and the first gear 26, and the pinion 33 is planet-rotated. The ring gear 32 and the second gear 27 rotate the output shaft 22 in the same direction as the steering wheel 9 to steer the output shaft 22. In this case, the rotations of the input and output shafts 22 are made substantially the same by selecting the number of gear teeth. Further, in a state where the torque control motor 38 fixes the input shaft 21 to perform torque assist so as to cancel the steering reaction force, the steering control motor 36 causes the sun gear 3 to rotate.
When 1 is rotated, the ring gear 32 is rotated by the rotation of the pinion 33.
And the output shaft 22 is rotated in the same direction via the second gear 27 and electrically steered.

As a control system, the input shaft 21 has a steering angle Qh.
Is provided with a steering angle sensor 40 for detecting the steering torque Th, and a steering angle sensor 42 for detecting the actual steering angle Qp is provided on the output shaft 22. Further, the motor shaft 24 of the gear ratio variable mechanism 25 is provided with a phase angle sensor 43 for detecting the phase angle Qs. Then, the image data of the image recognition control unit 15, the vehicle speed V of the vehicle speed sensor 44, and the signals of the sensors 40 to 43 are input to the automatic steering control unit 17 and electrically processed, and the steering signal is transmitted in the automatic steering mode. Output to the steering control motor 36,
It is configured to output a torque signal to the torque control motor 38.

In FIG. 1, the automatic steering control unit 17
Will be described. First, it has a distance calculation unit 50 to which the image data from the image recognition control unit 15 is input,
As described above, the predetermined distance position D on the image is set. The target trajectory setting unit 51 sets the target trajectory L1 by the white line at the predetermined distance position D based on the image data. Further, the vehicle has a predicted trajectory calculation unit 52 for inputting the vehicle speed V and the actual steering angle Qp, and calculates a predicted trajectory L2 of the vehicle 1 when traveling at a predetermined distance position D with the current position, direction, and traveling state of the vehicle. To do. Furthermore,
It has a mode setting unit 53 for setting, for example, an automatic steering mode in which the power of the control system is turned on and a manual steering mode in which the power is turned off by turning the selection switch 45 on and off.

The target trajectory L1, the predicted trajectory L2 and the mode signal described above are input to the deviation width calculator 54 to calculate the deviation width e between the target trajectory L1 and the predicted trajectory L2 in the automatic steering mode. The deviation width e is input to the steering angle calculation unit 55, and the indicated steering angle φ is calculated from the deviation width e and the proportional constant k. The instructed steering angle φ and the actual steering angle Qp are input to the control amount calculation unit 56, the control amount is calculated from the deviation between the two, and the drive unit 57 supplies the steering control motor 36 with a current Ip according to the control amount.
In the manual steering mode, the steering control motor 36 is supplied with a predetermined current Ip necessary for fixing the sun gear. The steering torque Th of the steering torque sensor 41 is input to the assist torque calculation unit 58, the steering torque Th corresponding to the steering reaction force acting on the steering wheel 9 side is detected in the automatic steering mode, and the steering reaction force is offset. Such an assist torque Ta is calculated. Then, the drive unit 59 is configured to supply the current Is according to the torque Ta to the torque control motor 38.

In the above control system, the automatic steering control for sudden turning will be described. In the gear ratio variable mechanism 25, the steering wheel side is fixedly controlled by assisting the torque control motor 38 in the same direction as the steering control motor 36 in the case of automatic steering. When the torque control motor 38 is positively rotated in the same direction as the steering control motor 36, the ring gear 32 on the tire side is rotated and steered by the sun gear 31 and the pinion 33, and the carrier 34 having a larger diameter than that is rotated. However, the steering amount and the steering force can be increased while receiving the steering reaction force by rotating in the same direction.

Therefore, the steering angular velocity detecting section 60 to which the actual steering angle Qp is input is provided to detect the steering angular velocity ωp. The steering angular velocity ωp and the mode signal are input to the rapid turning determination unit 61, and the steering state is determined based on the steering angular velocity ωp in the automatic steering mode. Then, when the steering angular velocity ωp is larger than the set value a, it is determined that the steering wheel is steered in the case of collision avoidance or the like. This rapid turning signal is input to the rotation control unit 62, and the torque control motor 38
Is configured to rotate in the same direction in conjunction with the steering control motor 36.

Next, the operation of this embodiment will be described. First, when the driver turns off the selection switch 45 while the vehicle is traveling, the automatic steering control unit 17 enters the manual steering mode, a predetermined current flows through the steering control motor 36, and the motor shaft 24 of the gear ratio variable mechanism 25 of the automatic steering power unit 14 is changed. And the sun gear 31 is fixed. Further, the torque control motor 38 does not operate and the input shaft 21 of the handle 9 becomes free. Then, when the driver grips the steering wheel 9 to steer as shown in FIG. 5A, the planetary gear 30 is operated with respect to the input shaft 21, the first and second gears 26 and 27 of the gear ratio variable mechanism 25, and the fixed sun gear 31. The output shaft 22 rotates in the same direction, and the front wheel 5 is freely steered left and right by the operation of the hydraulic power steering mechanism 23.

When the selection switch 45 is turned on, the automatic steering mode is selected. Therefore, in the automatic steering control unit 17, the target trajectory L1 such as the white line at the predetermined distance position D is set by the image data from the image recognition control unit 15, and the predetermined distance position D of the vehicle 1 is set by the vehicle speed V and the actual steering angle Qp.
The predicted trajectory L2 at is calculated. Then, the instructed steering angle φ is calculated according to the deviation width e between the target trajectory L1 and the predicted trajectory L2, and the steering control motor 36 is supplied with a current Ip of a control amount based on the instructed steering angle φ and the actual steering angle Qp. Therefore, in the gear ratio variable mechanism 25, the steering control motor 36 operates to rotate the worm gear 35, the motor shaft 24, and the sun gear 31, but at this time, since the ring gear 32 is heavily loaded on the tire side, the carrier 34 Etc. are reversed and the steering reaction force in this case acts on the steering wheel 9 side.

Then, the steering torque sensor 41 detects the steering reaction force in this case, the assist torque Ta for canceling the steering reaction force is calculated, and the current Is corresponding to the torque Ta flows into the torque control motor 38. Then, the torque control motor 38 and the worm gear 37 are operated, and torque assist is performed to fix the input shaft 21, the first gear 26, the carrier 34, and the like. Therefore, the steering control motor 3
When the sun gear 31 rotates by 6, the ring gear 32, the second gear 27, and the output shaft 22 rotate against the load on the tire side, and the front wheel 5 is released with the steering wheel released as shown in FIG. 5B.
Is automatically steered according to the steering signal. In this way, even if the driver does not operate the steering wheel 9, the front wheels 5 of the vehicle 1 are steered so as to follow the white line of the road, and the vehicle 1 safely follows the lane.

The control in the case of sudden turning will be described with reference to the flowchart of FIG. First, when the automatic steering mode is determined in step S1, the process proceeds to step S2, the steering control motor 36 is rotationally controlled, and in step S3, the torque control motor 38 is torque-controlled to operate. After that, the process proceeds to step S4, the steering angular velocity ωp is compared with the set value a,
In the case of normal gentle steering with the set value a or less, step S
Return to 2.

If there is an obstacle in front of the vehicle 1 when traveling on a general road, the steering angle φ is greatly increased / decreased so as to avoid a collision with the obstacle. The rotation of the motor 36 is also greatly increased / decreased and steered, and the steering angular velocity ωp is also increased. Therefore, when the steered angular velocity ωp becomes equal to or greater than the set value a and it is determined that the steered steering is to avoid the collision, the process proceeds from step S4 to step S5, and the torque control motor 38 is controlled to rotate in the same direction in cooperation with the steering control motor 36. .

Therefore, the variable gear ratio mechanism 25 operates as shown in FIG. That is, when the steering control motor 36 rotates the sun gear 31 of the planetary gear 30 to the right, for example as indicated by the arrow, the ring gear 32 rotates to the left by the left rotation of the pinion 33, so that the output shaft 22 rotates to the same right as the motor 36. Steered. At this time, the torque control motor 38 also rotates in the right direction in conjunction with the torque control motor 38.
4 rotates counterclockwise, and the pinion 33 planetarily rotates counterclockwise. Therefore, the left rotation of the ring gear 32 is accelerated, and the rotational force is also increased by the sun gear 31 and the carrier 34 having a larger diameter, so that the steering control motor 36 and the torque control motor 38 both receive the steering reaction force and steer the vehicle firmly. To be done. Therefore, while reducing the load on the steering control motor 36,
The large steering forces of the two motors 36 and 38 steer the vehicle quickly to reliably avoid collision with an obstacle.

Although the embodiment of the present invention has been described above, the invention can be applied to the case where the structure of the variable gear ratio mechanism is different.

[0028]

As described above, according to the present invention,
In an automatic steering device that operates the steering control motor and the torque control motor to perform automatic steering, both the steering control motor and the torque control motor steer in the case of sudden turning with a large steering angular velocity, so the load on the steering control motor must be ensured. It is possible to increase the steering force while reducing the amount, which eliminates the need for a high-output motor, which is advantageous in terms of cost. Further, it is possible to appropriately steer the vehicle by increasing the rudder force to avoid a collision with an obstacle in front of the vehicle. Since this is a method of controlling the rotation of the torque control motor by utilizing the structure of the gear ratio variable mechanism, the steering force and the like can be sufficiently increased while receiving the steering reaction force, and the control is easy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic steering control unit suitable for a control method for an automatic steering device according to the present invention.

FIG. 2 is a configuration diagram showing an overall outline of an ADA system.

FIG. 3 is a configuration diagram showing an automatic steering power unit.

FIG. 4 is a conceptual diagram of automatic steering control.

FIG. 5 is a diagram showing states of manual steering and automatic steering.

FIG. 6 is a flowchart showing automatic steering control in the case of rapid turning.

FIG. 7 is a diagram showing an operating state of a gear ratio variable mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 9 Steering wheel 10 Steering device 14 Automatic steering power unit 15 Image recognition control unit 17 Automatic steering control unit 25 Gear ratio variable mechanism 36 Steering control motor 38 Torque control motor 60 Steering angular velocity detection part 61 Rapid steering determination part 62 Rotation control part

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Claims (2)

[Claims] 1. A steering device for a vehicle is provided with a gear ratio variable mechanism that is equipped with a steering control motor and a torque control motor to automatically steer, and image data, vehicle speed, and actual steering angle in front of the vehicle in the automatic steering mode. The steering control motor is rotationally controlled by the signal of, and the torque control motor is torque controlled,
In an automatic steering device that automatically steers a running vehicle along a white line on the road without operating the steering wheel, determines whether the steering angular velocity of the actual steering angle is greater than the set value in the automatic steering mode, and sets If it is larger than the value, it is judged as a sudden turn,
A method for controlling an automatic steering device, characterized in that a torque control motor is controlled to rotate in the same turning direction in conjunction with a steering control motor. 2. The torque control motor controls the torque so as to offset the steering reaction force by applying an assist torque in the normal automatic steering mode, and rotates in the same direction as the steering control motor in the case of sudden turning. The control method for the automatic steering device according to claim 1, wherein the rotation is controlled so as to increase the steering force.