JP3622329B2 - Vehicle steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus, and more particularly to a vehicle steering apparatus used for a vehicle having an automatic driving function.
[0002]
[Prior art]
The automatic steering device is a device in which a hydraulic or electric power source is attached to a manual steering device and is forcibly moved by a machine. An example of conventional automatic steering is disclosed in, for example, Japanese Patent Laid-Open No. 7-156818. This recognizes a road situation and performs automatic steering based on the deflection angle found by the road situation recognition process.
[0003]
In addition, based on the ASV (advanced safety vehicle) concept proposed by the Ministry of Transport, research and development of passenger cars that take their own risk-avoidance behavior and vehicles that are partially autonomously driven on highways and the like have been conducted.
[0004]
Auto-steering is an element in such self-driving vehicle technology, and cannot be established with an auto-steering device alone. In addition, there are two types of automatic driving: fully automatic and semi-automatic (ASV). Here, semi-automatic automatic driving will be described on the premise that it is applied to an automobile.
[0005]
As semi-automatic automatic driving, it recognizes the white line and the preceding vehicle imaged by the CCD camera, and follows this white line and the preceding vehicle, and reads the magnetic tape embedded in the road in a non-contact manner, A device for operating a steering mechanism has been proposed.
[0006]
Furthermore, a method of steering the steering mechanism by an external sensor group only in an emergency, such as when a collision risk is assumed, has been proposed. For example, a method has been developed in which the degree of danger is calculated based on the inter-vehicle distance measuring device, the vehicle speed of the host vehicle, and the state of the brake, and processing such as alarm and automatic steering is performed based on the degree of danger. Yes.
[0007]
FIG. 12 shows a block diagram of a control device that performs automatic operation. As shown in FIG. 12, the automatic driving control device includes a traveling state sensor unit 71 that detects the traveling state of the vehicle, a tuner 72 that receives position information such as GPS signals, VICS, FM multiplex broadcasting, and road state information. An equipment controller 73 for controlling the operation of various equipment equipped on the vehicle, a vehicle body controller 74 for controlling the operation of each part of the vehicle body, and a main controller 75 are provided.
[0008]
The traveling state sensor unit 71 includes an external sensor 76 that captures an external state of the vehicle, and a vehicle sensor 77 that captures a vehicle body or a state inside the vehicle. As the external sensor 76, a CCD camera 76A that captures the traveling direction or the rear, a laser radar 76B that measures a distance from a front obstacle, an ultrasonic sensor that captures a distance from a running road, and the like. 76C, a white line in front of the vehicle, obstacles, and a stereo camera 76D for calculating the distance from the vehicle traveling ahead by the principle of triangulation.
[0009]
The vehicle sensor 77 includes a vehicle speed sensor, an engine speed sensor that detects the engine speed, a throttle opening sensor that captures the throttle opening, a gear position sensor that captures the gear position, a steering angle of the vehicle, It consists of various sensors that capture posture (gyro), vehicle interior temperature, water temperature, oil temperature, and the like.
[0010]
As the equipment controller 73, a monitor controller 73A for controlling a display for displaying map information, a door lock controller 73B for performing drive control such as releasing a door lock at the time of a collision by an actuator, or when a rear vehicle is confirmed. There are a signal lamp controller 73C that performs control such as displaying an alarm lamp indicating the presence of the host vehicle, and an air bag controller 73D that controls the air bag.
[0011]
The vehicle body controller includes a transmission controller 74A for controlling transmission such as A / T, an engine controller 74B for controlling EPI and valve, a throttle controller 74C for controlling throttle, and a brake controller 74D for controlling brake such as ABS. In addition, there is a steering controller 74E for controlling the steering.
[0012]
The main controller 75 adjusts between various controls based on outputs from various sensors that detect the running state and various information received by the tuner 72. The main controller 75 is also provided with a database 78 such as a CD-ROM.
[0013]
With the configuration shown in FIG. 12, the automatic driving control device captures the driving state and controls the driving of the equipment and the vehicle body based on the database such as GPS, other public broadcasts, and map data. is there.
[0014]
Conventionally, an electric power steering has been used. The power steering mechanism urges and suppresses the steering force applied to the steering wheel. As a power steering device for electronically controlling the steering assist amount, there is one disclosed in Japanese Patent Laid-Open No. 7-186992. In this method, the target assist amount is calculated from the vehicle speed and a coefficient corresponding to the steering angle.
[0015]
FIG. 13 is a graph showing an outline of the steering force and the steering angle diagram. During the operation of the power steering mechanism, the assist amount is determined from the operation amount applied to the steering wheel and the necessary amount necessary for steering. The assist amount has a relationship as illustrated with respect to the steering angle. Further, in FIG. 13, the value of x [degree] is a so-called assist amount at the time of switching.
[0016]
In the conventional power steering mechanism, a torque sensor is provided to capture the operation amount applied to the steering wheel. FIG. 14 is a graph showing the relationship between the torque sensor output and the assist amount. The vertical axis represents the voltage output of the torque sensor for the straight line indicating the torque sensor output, and the assist amount (motor output) for the dotted line indicating the motor output.
[0017]
Conventionally, the assist amount is controlled by changing the assist amount according to the vehicle speed. In the example shown in FIG. 14, the assist amount is increased as shown in the figure when it is determined that the vehicle is steered at low speed. . On the other hand, the amount of assist is reduced during high-speed driving. The assist amount calculation process is performed according to a predetermined assist amount determination map.
[0018]
In addition, a dead zone is provided for the torque sensor output, and when the voltage output of the torque sensor exceeds the threshold value A, the motor output is first made.
[0019]
FIG. 15 is an explanatory diagram showing an example of a running state. Further examination of the dead zone in FIG. 14 reveals that the conventional power steering mechanism adopts a configuration in which the power steering region 74a and the non-power assist region 74b are switched according to the threshold value A that defines the dead zone.
[0020]
FIG. 16 is an explanatory diagram showing an example of power steering control according to FIGS. 13 and 14. As shown in the figure, the assist amount is large during acceleration, and the assist amount is small during traveling at a constant speed.
[0021]
[Problems to be solved by the invention]
In the conventional example in which automatic driving is performed, a switch or the like is required for switching between “automatic” and “manual” of a passenger car that can be automatically driven. Because there is a possibility that the response will be delayed in an emergency such as a machine malfunction, etc., and switching from `` manual '' to `` automatic '' with a switch etc., the switch operation itself must be performed during driving steering, Not desirable.
[0022]
A conventional example for switching between the power steering mode and the automatic steering mode is disclosed in Japanese Patent Laid-Open No. 7-205831. This is to provide stable automatic steering even immediately after switching by providing a predetermined time lag at the time of switching.
[0023]
In some cases, automatic steering may be prioritized, but automatic steering priority control cannot be performed with a switch. Furthermore, there is no known proposal to use a motor for performing automatic steering as a motor for driving a power steering mechanism during manual steering.
[0024]
OBJECT OF THE INVENTION
The present invention improves the inconvenience of such a conventional example, and in particular, to provide a vehicle steering apparatus that can accurately capture the driver's intention and switch between automatic driving and manual driving without using a switch. For that purpose.
[0025]
[Means for Solving the Problems]
Therefore, in the present invention, a steering mechanism that changes the direction of the steering wheel, a steering force transmission means that transmits a steering force from the driver to the steering mechanism, and a traveling state sensor that captures a traveling state such as the vehicle speed of the host vehicle. And an automatic steering control unit for calculating a target steering amount based on the traveling state of the host vehicle captured by the traveling state sensor unit when a predetermined automatic steering mode is set, and the automatic steering control unit. And a motor for driving the steering mechanism in accordance with the target steering amount. Moreover, the running state sensor unit includes a torque sensor that detects the magnitude of the steering force from the driver.
Further, the automatic steering control unit switches the control to set the automatic steering mode when the torque sensor output is less than a predetermined threshold and to set the power steering mode when the output from the torque sensor is equal to or higher than the predetermined threshold. A threshold value changing unit that changes the threshold value according to the vehicle speed captured by the driving state sensor unit, and when the power steering mode is set by the switching control unit, depending on the driving state of the host vehicle A power steering control unit that calculates a target steering amount for energizing or suppressing the steering force from the driver is also provided.
Further, the motor drive for controlling the motor based on the target steering amount calculated by the automatic steering control unit or the target steering amount calculated by the power steering control unit according to each mode set by the switching control unit. It adopts the configuration of having a control unit.
[0026]
With the above configuration, the threshold value changing unit changes the threshold value according to the vehicle speed captured by the traveling state sensor unit. Then, calculating the switching control unit sets the automatic steering mode when the torque sensor output is less than the threshold, the automatic steering control unit, a target steering amount in accordance with the running state of the during the automatic steering mode the vehicle and, on the other hand, the switching control unit is set to the power steering mode when the output from the torque sensor is equal to or greater than the threshold value, the power steering control unit, in the power steering mode on the vehicle running state such as a vehicle speed Accordingly, in order to calculate the target steering amount that adds or suppresses the steering force from the driver, automatic steering and manual operation are switched according to the steering force from the driver to the steering wheel. Performs a power steering operation by a motor used for automatic steering.
[0027]
Further, the threshold value changing unit is configured to increase the threshold value during high-speed driving and decrease the threshold value during low-speed driving according to the vehicle speed captured by the driving state sensor unit. Control that does not simply switch between the automatic steering mode and the power steering mode during traveling is realized .
[0028]
The present invention intends to achieve the above-described object by each of these means.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
FIG. 1 is a block diagram showing the configuration of a vehicle steering apparatus according to the present invention. The vehicle steering apparatus includes a steering mechanism 4 that changes the direction of the steering wheel, a steering force transmission means 6 that transmits a steering force from the driver to the steering mechanism, and a traveling state that captures a traveling state such as the vehicle speed of the host vehicle. A sensor unit 10; an automatic steering control unit 12 for calculating a target steering amount based on the traveling state of the host vehicle captured by the traveling state sensor unit 10 when the automatic steering mode is set in response to a predetermined switching signal; The motor 2 that drives the steering mechanism 4 according to the target steering amount calculated by the automatic steering control unit 12 is provided.
[0031]
Moreover, the traveling state sensor unit 10 includes a torque sensor 11 that detects the magnitude of the steering force from the driver. The traveling state sensor unit 10 is the same as the conventional traveling state sensor unit 71 shown in FIG.
[0032]
Further, when the torque sensor output is less than a predetermined threshold value, the automatic steering control unit 12 outputs a switching signal to the automatic steering control unit 12, and when the output from the torque sensor 11 is equal to or higher than the predetermined threshold value, the power is output. A switching control unit 18 for setting the steering mode, and a target steering amount for energizing or suppressing the steering force from the driver according to the traveling state of the vehicle when the power steering mode is set by the switching control unit 18 are calculated. A power steering control unit 14 is also provided.
[0033]
Further, the motor 2 is connected to the motor 2 based on the target steering amount calculated by the automatic steering control unit 12 or the target steering amount calculated by the power steering control unit 14 according to each mode set in the switching control unit 18. A motor drive control unit 16 for drive control is also provided.
[0034]
Further, the switching control unit 18 is provided with a threshold value changing unit 20 that changes the threshold value according to the vehicle speed captured by the traveling state sensor unit 10.
[0035]
This will be described in detail.
[0036]
In this embodiment, the motor 2 is also used as a power source for automatic steering and an auxiliary power source (power assist) during manual steering. Furthermore, a torque sensor attached to the electric power steering is used as a switch for switching between the automatic steering mode and the power steering mode. This eliminates the switch switching operation and improves operability.
[0037]
FIG. 2A is a perspective view showing the configuration of the steering force transmission means 6, and FIG. 2B is a schematic view thereof. As shown in the figure, the steering force transmission means 6 includes a steering wheel (handle) 61, a rotating shaft (steering column) 64, a torque sensor 11 for detecting a steering force applied to the steering wheel, and a steering wheel. And a steering angle sensor 63 that captures the rotation of the steering column due to the applied steering force and the driving force applied by the motor 2. The rudder angle sensor 63 is constituted by, for example, a potentiometer or a rotary encoder.
[0038]
Since the motor performs automatic steering, the output is increased as compared with the conventional motor. The rotational force of this motor is transmitted to the rotating shaft 64 via the worm wheel gear 65.
[0039]
In this embodiment, the ASV controller 12 is employed as the automatic steering control unit. Further, the power steering control unit 14, the motor drive control unit 16 and the switching control unit 18 are realized as functions of the steering controller 22.
[0040]
As shown in FIG. 3, a vehicle speed sensor 31, an engine speed sensor 32, and an ignition switch 33 are connected to the steering controller 22. Further, the steering angle sensor (potentiometer) 63 and the torque sensor 11 are connected to the steering controller 22. Further, the motor 2 described above and a current sensor 64 for driving control of the motor 2 are connected.
[0041]
FIG. 4 is an explanatory diagram showing an example of switching between the power steering mode and the automatic steering mode. Based on a predetermined threshold value A, the switching control unit 18 stops automatic steering when the torque sensor output exceeds the threshold value A, and switches to manual operation. Further, when the manual operation is switched, the power steering control unit 14 calculates an assist amount (target steering amount) corresponding to the torque output based on the power steering map. Then, the motor drive control unit 16 performs control for energizing or suppressing the steering force applied to the handle 61 based on the target steering amount.
[0042]
Further, in this embodiment, the threshold value A is variable. The threshold value changing unit 20 first changes the threshold value according to the vehicle speed output from the traveling state sensor unit 10. Specifically, the threshold value is increased during high-speed traveling, and the threshold value is decreased during low-speed traveling. This is a control that does not easily switch between the automatic steering mode and the power steering mode during high-speed traveling.
[0043]
Further, even when the automatic steering control unit 12 determines that the degree of risk is large, the threshold A for switching from the automatic steering mode to the power steering mode is increased. As a result, when the degree of danger is high, control is performed such that automatic steering is prioritized.
[0044]
The setting control of the threshold value A will be described with reference to FIGS.
[0045]
FIG. 5 is an explanatory diagram showing the relationship between the torque sensor output and the motor output when the vehicle speed is 10 [km / h] or less and there is no danger data. The threshold value in the state shown in FIG. Here, since it is considered that the vehicle is stopped or in the garage, it is determined that the steering is for steering, and the assist amount (motor output) is increased.
[0046]
FIG. 6 is an explanatory diagram showing a case where the vehicle speed is 50 [km / h] or less and there is no danger data. In the state shown in FIG. 6, the threshold value A1 is shifted to A2. As shown in FIG. 6, when the torque output is increased in the automatic steering mode, the mode is switched to the power steering mode when the threshold value A2 is exceeded instead of the threshold value A1. For this reason, the control is performed by switching the torque output so that it can be determined that the driver operates the steering wheel more clearly without switching between automatic steering and manual steering with a small force applied to the steering wheel.
[0047]
FIG. 7 is an explanatory diagram showing a case where there is further danger data in the state shown in FIG. In the state shown in FIG. 7, the automatic steering area 12a is further expanded and the threshold value is changed to A3. For this reason, when the degree of danger is greater than a certain value, such as when an obstacle is recognized, an active danger avoiding operation (automatic steering) can be performed by changing the threshold value. Further, when there is danger data, automatic steering is prioritized, and when a strong steering force is applied from the driver, the steering wheel direction can be changed by the steering.
[0048]
FIG. 8 is an explanatory diagram showing the case of high-speed traveling, and shows a case where the vehicle speed is 80 km / h or more and there is no danger data. In the example shown in the figure, the threshold value is further increased to A4 so that the automatic steering mode and the power steering mode are not easily switched during high-speed driving.
[0049]
FIG. 9 is a time chart showing motor drive control timing according to the configuration shown in FIGS. FIG. 10 is a flowchart showing an example of the drive control process of the motor 2.
[0050]
The main switch is turned on (step S1), and first, various sensor data captured by the traveling state sensor unit 10 is captured (step S2). For example, the vehicle speed, the steering angle, the torque sensor value, and the like. Based on these values, the automatic steering control unit 12 generates automatic steering data, and also generates inter-vehicle distance data and danger data.
[0051]
Next, the presence / absence of an abnormality is confirmed (step S3). If there is an abnormality, a warning is issued and the motor clutch 62 is turned off (step S4).
[0052]
If there is no abnormality, the threshold value A is determined from the values of various data such as the vehicle speed (step S5), and the threshold value A is compared with the torque value (step S6). As shown in FIG. 5 to FIG. 8, the threshold value A is determined by first determining the vehicle speed and further adjusting it according to the danger data.
[0053]
From this comparison result, whether automatic steering or power steering is determined (steps S7 and S8), the target steering amount from the automatic steering control unit 12 or the power steering control unit 14 is calculated. Next, the motor drive control unit (motor driver) 16 drives the motor 2.
[0054]
The control cycle shown in FIG. 9 is 1 [msec] or less, but is variable depending on the running state.
[0055]
FIG. 11 is an explanatory diagram showing an example of traveling by the drive control shown in FIG.
[0056]
When the engine is started and the steering force by the driver is not detected, automatic steering is applied, and the engine operates based on a command from the automatic steering control unit 12. When a vehicle speed or the like is detected, the automatic steering control unit 12 determines a necessary steering angle from data of various sensors 10 and gives a target steering amount to the motor drive control unit 16.
[0057]
When the steering force of the steering wheel (steering wheel) is detected by the torque sensor 63, the switching control unit 18 switches to the power steering operation.
[0058]
The threshold value changing unit 20 sets a threshold value A for switching control based on torque sensor output according to the vehicle speed and the degree of danger. For this reason, automatic steering is continued when the torque sensor output is equal to or less than the threshold value set in accordance with the running state.
[0059]
【The invention's effect】
Since the present invention is configured and functions as described above, according to this, the torque sensor detects the magnitude of the steering force from the driver, and the switching control unit detects that the torque sensor output is less than a predetermined threshold value. Sometimes the automatic steering mode is set, and the automatic steering control unit can accurately detect the steering force applied to the steering wheel in order to calculate the target steering amount according to the traveling state of the vehicle during the automatic steering mode. In addition, when a steering force is not applied to the steering wheel, for example, when the vehicle is running in a straight line, it is possible to switch from manual steering to automatic steering. Further, the switching control unit outputs an output from the torque sensor to a predetermined threshold value. In this case, the power steering mode is set. Therefore, when the driver operates the steering wheel during automatic steering, the automatic steering is stopped when the steering force exceeds a certain value. It is possible to switch to the dynamic steering. Furthermore, since the power steering control unit calculates a target steering amount that energizes or suppresses the steering force from the driver according to the traveling state of the host vehicle such as the vehicle speed during the power steering mode, the motor drive control unit The motor for automatic steering can be used for power steering operation during manual steering, which improves operability. In this way, the switching control unit switches between automatic steering and manual steering by comparing the torque sensor output and the threshold value set by the threshold value changing unit, so the driver's intention is accurately captured regardless of the switch. Thus, it is possible to provide an unprecedented excellent vehicle steering device capable of switching between automatic driving and manual driving.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.
2 is an explanatory diagram showing a configuration of the steering force transmission means shown in FIG. 1, FIG. 2 (A) is a diagram showing an external configuration, and FIG. 2 (B) is a schematic diagram thereof.
3 is a block diagram showing a configuration of hardware resources of a control system of the vehicle steering apparatus shown in FIG. 1. FIG.
4 is an explanatory diagram showing an example of switching between an automatic steering mode and a power steering mode by a switching control unit shown in FIG. 1. FIG.
FIG. 5 is a graph showing a relationship between a torque sensor output and a motor output based on a threshold value A1 at a low speed.
FIG. 6 is a graph showing a relationship between a torque sensor output and a motor output based on a threshold value A2 at medium speed.
FIG. 7 is a graph showing the relationship between the torque sensor output and the motor output based on the threshold value A3 when there is danger data at medium speed.
FIG. 8 is a graph showing a relationship between a torque sensor output and a motor output based on a threshold value A4 at high speed.
FIG. 9 is a time chart showing the timing of motor drive control in the configuration shown in FIG. 1;
10 is a flowchart showing processing steps of motor drive control in the configuration shown in FIG. 1. FIG.
11 is an explanatory diagram showing an example of vehicle travel according to the flowchart shown in FIG.
FIG. 12 is a block diagram showing a configuration of a conventional automatic driving apparatus.
FIG. 13 is a graph showing an assist amount of a conventional power steering mechanism.
FIG. 14 is an explanatory diagram showing motor output according to vehicle speed of a conventional power steering mechanism.
FIG. 15 is an explanatory view showing a dead zone of a conventional power steering mechanism.
FIG. 16 is an explanatory diagram showing an operation example of a conventional power steering mechanism.
[Explanation of symbols]
2 Motor 4 Steering mechanism 6 Steering force transmission means 10 Traveling state sensor unit 12 Automatic steering control unit 14 Power steering control unit 16 Motor drive control unit 18 Switching control unit 20 Threshold change unit

Claims (2)

A steering mechanism that changes the direction of the steering wheel, a steering force transmission means that transmits a steering force from the driver to the steering mechanism, a traveling state sensor unit that captures a traveling state such as the vehicle speed of the host vehicle, and a predetermined automatic When the steering mode is set, an automatic steering control unit that calculates a target steering amount based on the traveling state of the host vehicle captured by the traveling state sensor unit, and a target steering amount calculated by the automatic steering control unit. In response to this, the vehicle steering apparatus includes a motor that drives the steering mechanism.
The running state sensor unit includes a torque sensor that detects the magnitude of the steering force from the driver,
When the output from the torque sensor is less than a predetermined threshold, the automatic steering control unit is set to the automatic steering mode, and when the output from the torque sensor is equal to or higher than the predetermined threshold, the power steering mode is set. A switching control unit, a threshold value changing unit that changes the threshold value according to the vehicle speed captured by the traveling state sensor unit , and the traveling of the host vehicle when a power steering mode is set by the switching control unit. A power steering control unit for calculating a target steering amount for energizing or suppressing the steering force from the driver according to the state;
Drive control of the motor based on the target steering amount calculated by the automatic steering control unit or the target steering amount calculated by the power steering control unit according to each mode set by the switching control unit A vehicle steering apparatus characterized in that a motor drive control unit is provided. The threshold value changing unit changes the threshold value so as to increase the threshold value during high speed driving and to decrease the threshold value during low speed driving according to the vehicle speed captured by the driving state sensor unit. The vehicle steering apparatus according to claim 1, wherein:

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