JP2002333922A - Automatic steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic steering device capable of automatically steering a vehicle based on an electric steering instruction, which can enhance the safety of steering control at the time of a high speed traveling, and enhance the safety of the steering control according to the situation of a road. SOLUTION: When defining the changing amounts of the real steering position of steering wheels (6) or a steering actuator (4) per unit time as a steering speed, and defining a difference between the neutral position and real steering position of the steering wheels (6) or the steering actuator (4) as steering amounts, the allowable upper limit value of the steering speed and/or the steering amounts is preliminarily made correspond to the speed as an upper limit steering speed and/or upper limit steering amounts in a memory (24) so as to be made smaller according as the speed is made higher. Then, a steering control means (2) corrects the upper limit steering amounts and/or the upper limit steering amounts calculated by referring to the memory from the speed detected by a speed sensor (3) according to the detected result of a friction coefficient deterioration sensor (7), and controls the steering speed and/or the steering amounts based on a steering instruction to not more than the corrected upper limit steering speed and/or upper limit steering amounts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering system, and more particularly to an automatic steering system for steering a vehicle based on an electric steering command.

[0002]

2. Description of the Related Art In recent years, a steering device has been developed in which a vehicle is steered using hydraulic pressure or a motor as power. In such a steering device, an arbitrary steering amount can be obtained by an electric steering command. Conventionally, the driver can operate the steering wheel to automate the steering.

[0003] Examples of automatic steering include lane tracing on a highway and automatic parking at a low speed. In such automatic steering, a steering command is given to a steering device based on information from a lane detection sensor, a vehicle attitude sensor, and the like.

[0004]

In automatic steering, when a sensor abnormality is detected or a sensor failure occurs, an excessive steering command may be issued. In particular, when such an excessive steering command is given to the steering device during high-speed traveling,
It is dangerous because it causes vehicle spin and rollover.

Further, there is a problem that the risk of vehicle spin or rollover increases due to a decrease in the coefficient of friction due to road surface conditions such as wetness or freezing. Therefore, the present invention relates to an automatic steering device that automatically performs steering of a vehicle based on an electric steering command, and in particular, to enhance the safety of steering control during high-speed running, and to improve the safety of steering control according to road surface conditions. The purpose is to increase.

[0006]

SUMMARY OF THE INVENTION [1] Accordingly, an automatic steering apparatus according to the present invention includes a friction coefficient reduction sensor that detects a decrease in road surface friction coefficient, a vehicle speed sensor that detects a vehicle speed,
An actual steering position sensor that detects an actual steering position of the steered wheel or the steering actuator; and, when an amount of change in the actual steering position per unit time is used as a steering speed, an allowable steering speed as the vehicle speed increases. A memory in which the vehicle speed and the upper limit steering speed are previously associated with each other so that the upper limit steering speed, which is the upper limit value, is smaller; and the upper limit steering speed obtained by referring to the memory from the vehicle speed is determined by the friction coefficient lowering sensor. And a steering control means for performing correction in accordance with the detection result and controlling the steering speed based on the steering command to be equal to or less than the corrected upper limit steering speed.

That is, assuming that the amount of change per unit time of the actual position of the steered wheel or the steering actuator detected by the actual steering position sensor is the steering speed, the upper limit of the allowable steering speed according to the vehicle speed is set to the upper limit steering speed. Can be determined as In consideration of safety, the upper limit steering speed decreases as the vehicle speed increases. Therefore, the vehicle speed and the upper limit steering speed are associated in advance in the memory.

The steering control means obtains an upper limit steering speed by referring to a memory from the vehicle speed detected by the vehicle speed sensor.
The upper limit steering speed is corrected according to the detection result of the friction coefficient lowering sensor, and control is performed so that the steering speed based on the steering command does not exceed the corrected upper limit steering speed.

[0009] Thus, particularly during high-speed running, the steering is performed at a steering speed that is high enough to cause a danger of vehicle spin or rollover due to abnormality detection of various sensors for detecting information on which a steering command is based or sensor failure. When a steering command for steering a wheel is issued, control can be performed such that the steering speed is equal to or lower than the upper limit steering speed.

In this case, since the upper limit steering speed is corrected in accordance with the detection result of the friction coefficient lowering sensor, the safety of automatic steering is improved in accordance with the road surface condition (wet or frozen state indicated by the friction coefficient). It becomes possible. [2] Also, in the automatic steering device according to the present invention [1], when the difference between the neutral position of the steered wheel or the steering actuator and the actual steering position is used as the steering amount, However, instead of the upper limit steering speed, the vehicle speed and the upper limit steering amount are associated in advance so that the upper limit steering amount, which is the upper limit of the allowable steering amount, becomes smaller as the vehicle speed increases. The control means corrects the upper limit steering amount obtained by referring to the memory from the vehicle speed according to the detection result of the friction coefficient lowering sensor, and the steering amount based on the steering command is equal to or less than the corrected upper limit steering amount. May be controlled so that

That is, assuming that the difference between the neutral position and the actual steering position of the steered wheel or the steering actuator is the steering amount, the allowable upper limit of the steering amount can be determined as the upper limit steering amount according to the vehicle speed. In consideration of safety, the upper limit steering amount decreases as the vehicle speed increases, so the memory contains
The vehicle speed and the upper limit steering amount are associated in advance.

The steering control means obtains an upper limit steering amount from the vehicle speed detected by the vehicle speed sensor with reference to a memory, further corrects the upper limit steering amount according to the detection result of the friction coefficient reduction sensor, and performs steering based on a steering command. Control is performed so that the amount does not exceed the corrected upper limit steering amount. In steering a vehicle, at low speeds, there is a case where the entire range of the left and right steering amount of the vehicle is used,
When driving at high speeds, considering that it is used within the range of the tire grip circle, a small amount of left and right steering around the neutral position of the steering wheel is sufficient, and steering with an excessive steering amount is There is a risk of spinning or rolling over.

[0013] Therefore, a steering command is issued such that the steering is performed with an amount of danger such as vehicle spin or rollover due to abnormality detection of various sensors for detecting information on which the steering command is based or sensor failure. In this case, if the steering amount is controlled to be within the upper limit steering amount, it is possible to enhance the safety of the steering control particularly during high-speed running.

In this case, the upper limit steering amount is corrected according to the detection result of the friction coefficient lowering sensor, so that the safety of automatic steering can be further improved according to the road surface condition. [3] Also, in the automatic steering device according to the above-mentioned present invention [1], when the difference between the neutral position of the steered wheel or the steering actuator and the actual steering position is used as the steering amount, However, in addition to the upper limit steering speed, the vehicle speed and the upper limit steering amount are associated in advance so that the upper limit steering amount which is the upper limit of the allowable steering amount decreases as the vehicle speed increases. The control means corrects the upper limit steering speed and the upper limit steering amount obtained by referring to the memory from the vehicle speed according to the detection result of the friction coefficient reduction sensor, and the steering speed and the steering amount based on the steering command are adjusted. Control may be performed so as to be equal to or less than the corrected upper limit steering speed and upper limit steering amount.

That is, assuming that the difference between the neutral position and the actual steering position of the steered wheel or the steering actuator is the steering amount, the allowable upper limit of the steering amount can be determined as the upper limit steering amount according to the vehicle speed. In consideration of safety, the upper limit steering amount decreases as the vehicle speed increases, so the memory contains
The upper limit steering amount and the upper limit steering amount are associated with the vehicle speed in advance.

The steering control means obtains the upper limit steering speed and the upper limit steering amount by referring to the memory from the vehicle speed detected by the vehicle speed sensor, and further calculates the upper limit steering speed and the upper limit steering amount according to the detection result of the friction coefficient reduction sensor. The correction is performed so that the steering speed and the steering amount based on the steering command do not exceed the corrected upper limit steering speed and the corrected upper limit steering amount.

As described above, the steering speed and the steering amount are both limited to the upper limit or less, and the upper limit steering speed and the upper limit steering amount are respectively corrected according to the detection result of the friction coefficient reduction sensor. It is possible to enhance the safety of the steering control at the time of and the safety of the automatic steering according to the road surface condition.

[4] Also, in the automatic steering apparatus according to the present invention, in the above inventions [1] to [3], the friction coefficient reduction sensor may detect the reduction of the friction coefficient by mounting the wiper apparatus on a vehicle. May be detected. That is, the friction coefficient decrease sensor detects a decrease in the friction coefficient by the operation of the wiper device mounted on the vehicle. This is because, since the operation of the wiper device is accompanied by rainfall, it can be estimated that the higher the operation speed of the wiper device, the higher the degree of wetness of the road surface and the lower the friction coefficient.

[5] Further, in the automatic steering apparatus according to the present invention, in the above-mentioned inventions [1] to [3], the friction coefficient decrease sensor detects the decrease in the friction coefficient by the outside air temperature mounted on the vehicle. It may be detected by a sensor. That is, the friction coefficient decrease sensor detects a decrease in the friction coefficient by the outside air temperature sensor mounted on the vehicle. This is because when the outside air temperature detected by the outside air temperature sensor is lower than zero, a decrease in the friction coefficient due to the freezing of the road surface can be estimated.

[6] In the automatic steering device according to the present invention, in the above inventions [1] to [3], the friction coefficient reduction sensor is provided by a road surface information providing device installed on the road side. Communication means for receiving the road surface information, and the decrease in the friction coefficient may be detected based on the road surface information.

That is, when the road surface information providing device is installed on the road side, the friction coefficient reduction sensor has a means for receiving the provided road surface information (wet or frozen state, etc.), so that the friction coefficient is reduced from the received road surface information. Detects a decrease in coefficient. [7] Also, in the automatic steering device according to the present invention [1] or [3], when the steering speed based on the steering command exceeds the corrected upper limit steering speed, the steering control means may be used. However, control may be performed so as to maintain the current actual steering position.

That is, when the steering speed based on the steering command exceeds the corrected upper limit steering speed, the steering control means does not perform the steering according to the steering command, and holds the current actual steering position (the actual steering position is not changed). Lock). This makes it possible to enhance safety by maintaining the current state when a dangerous steering speed steering command is given.

[8] In the automatic steering device according to the present invention [1] or [3], when the steering speed based on the steering command exceeds the corrected upper limit steering speed, The steering means may be controlled to steer at the corrected upper limit steering speed. That is, the steering control means
When the steering speed based on the steering command exceeds the corrected upper steering speed, the steering is performed using the corrected upper steering speed instead of the steering speed based on the steering command (the steering speed is locked at the upper steering speed). Control.

Thus, when a dangerous steering speed steering command is given, it is possible to perform steering within a safe steering speed range. [9] Further, in the automatic steering device according to the present invention [2] or [3], when the steering amount based on the steering command exceeds the corrected upper limit steering amount, the steering control is performed. The means may be controlled to maintain the current actual steering position.

That is, when the steering amount based on the steering command exceeds the upper limit steering amount, the steering control means does not perform the steering according to the steering command and holds the current actual steering position (locks the actual steering position). Control. This makes it possible to enhance safety by maintaining the current state when a dangerous steering amount steering command is given.

[10] In the automatic steering device according to the present invention [2] or [3], when the steering amount based on the steering command exceeds the corrected upper limit steering amount, The steering means may be controlled so as to steer at the upper limit steering amount. That is, when the steering amount based on the steering command exceeds the corrected upper limit steering amount, the steering control means performs steering using the upper limit steering amount instead of the steering amount based on the steering command (the steering amount is locked to the upper limit steering amount). Control).

Thus, when a dangerous steering amount steering command is given, it is possible to perform steering within a safe steering amount range.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment (1): FIG. 1 FIG . 1 shows an embodiment (1) of an automatic steering apparatus according to the present invention, and a steering command comprising a final target steering position and a target steering speed. Steering position to be calculated and given to the steering control device 2 /
A steering speed calculating unit 1, a vehicle speed sensor 3 for detecting a vehicle speed, a steering actuator 4 for steering a steered wheel 6 under the control of a steering control device 2, an actual steering position sensor for detecting an actual steering position of the steered wheel 6 or the steering actuator 4. 5 and a vehicle wiper switch 7.

The steering position / steering speed calculation section 1 includes a traveling path detecting section 11 for detecting a traveling path (a lane or the like) on which the vehicle travels, and a self-vehicle state detecting section for detecting a traveling state (such as a traveling direction) of the own vehicle. 12,
A traveling pattern determining unit 13 that determines a steering pattern (maintaining in a lane, etc.) of the own vehicle according to a driver instruction, a target traveling locus calculation unit 14 that calculates a traveling locus of the own vehicle, and a steering command that calculates a value of a steering command. It comprises a value calculation unit 15.

The steering control device 2 includes an input unit 21 for inputting signals necessary for steering control, a CPU 22 for performing calculations and determinations regarding steering control, a RAM 23, a ROM 24 storing control programs and control parameters, and a steering actuator 4. The vehicle includes an output unit 25 that outputs a signal for driving, and a power supply unit 26 that generates and supplies power required for each unit in the steering control device 2 from a vehicle power supply.

In operation, the target travel trajectory calculation section 14 of the steering position / steering speed calculation section 1 performs the target travel trajectory calculation based on information from the travel path detection section 11, the own vehicle situation detection section 12, and the travel pattern determination section 13. Is calculated and given to the steering command value calculation unit 15. In addition, the steering command value calculation unit 15 includes a target travel locus calculation unit.
The final target steering position and the target steering speed are calculated as the steering command value based on the calculation result in 14, and are given to the steering control device 2.

The input section 21 of the steering control device 2 has a steering position /
The steering command value from the steering speed calculation unit 1, the vehicle speed information from the vehicle speed sensor 3, the actual steering position information from the actual steering position sensor 5, and the wiper operation information from the vehicle wiper switch 7 are read and given to the CPU 22. The CPU 22 performs calculations and determinations regarding steering control using the RAM 23 and the ROM 24.
The steering actuator 4 is driven according to the output of U22.

Embodiment (2): FIG. 1 Embodiment (2) has an outside temperature sensor 8 instead of or in addition to the vehicle wiper switch 7 shown in FIG. This can be performed in the same manner as in the embodiment (1). In this case, the input unit 21 of the steering control device 2 includes:
Outside temperature information from the outside temperature sensor 8 is input.

Embodiment (3): FIG. 2 FIG . 2 shows an embodiment (3) of the automatic steering system according to the present invention, wherein road surface information is used instead of the vehicle wiper switch 7 in the embodiment (1). There is provided a receiver 9 connected to an antenna 10 for receiving the signal, and the other configuration is the same as that of the embodiment (1). The road surface information is provided by a road surface information providing device (not shown) installed on the road side.

In the embodiment (3), the input unit 21 of the steering control device 2
, The road surface information received by the receiver 9 via the antenna 10 is input. Operation Example: FIGS. 3 to 5 Hereinafter, a steering control operation by the steering control device 2 in FIGS. 1 and 2 will be described with reference to flowcharts shown in FIGS. FIG. 5 shows a process common to all the embodiments (1) to (3), and corresponds to FIGS. 3 and 5 corresponding to the embodiments (1) and (2). 5 shows a process executed subsequent to the corresponding process shown in FIG.

It is assumed that the processing shown in the flowchart is executed in a predetermined time (for example, 100 msec) cycle. In addition, the actual steering position, the final target steering position, and the target steering position are represented by "0" for a neutral state, "+" for right turning, and "-" for left turning. Further, the target steering speed is a change amount of the actual steering position per unit time (for example, 100 msec), and the target steering speed is set to ≧ 0.

Operation corresponding to the embodiment (1) : FIG. 3 In the embodiment (1), when the processing of FIG. 3 is started, the actual steering position, the vehicle speed, the final target steering position, The target steering speed and the vehicle wiper operation information are read. These signals are input from the actual steering position sensor 5, the vehicle speed sensor 3, the steering position / steering speed calculator 1, and the vehicle wiper switch 7.

Next, in step S2, an upper limit steering amount which is an upper limit value of the steering amount allowable in the automatic steering is calculated.
The upper limit steering amount is a basic value, and a range in which the vehicle does not lose stability is obtained in advance by experiments or the like using the vehicle speed as a parameter, and is stored in advance in the ROM 24 shown in FIG.

The portion shown in black in the graph outside the frame of step S2 is the control range of the steering amount, and the control range is widened in proportion to the vehicle speed. This means that the upper limit steering amount in right and left steering is inversely proportional to the vehicle speed. In step S3, the basic value of the upper limit steering amount obtained in step S2 is
The upper limit steering amount is corrected by multiplying by a correction coefficient K1 according to the vehicle wiper operation status.

The correction coefficient K1 is obtained by an experiment or the like as a value equal to or less than "1". As shown in the graph outside the frame of step S3, the state of the wiper switch is set to "OFF".
And the value becomes smaller as the wiper operation speeds up in the order of "INT", "LO", and "HI". Note that the correction coefficient K1 is stored in advance in the ROM 24 shown in FIG.

In step S4, it is determined whether or not the final target steering position input in step S1 is within the regulation range. In this case, since the upper limit steering amount is multiplied by the correction coefficient K1, the restricted range after correction is wider than the restricted range based on the basic value of the upper limit steering amount. If not, the process proceeds to step S5, but if it is, the final target steering position is changed in step S5.

The process in step S5 is performed when the current actual steering position is held as indicated by ALT1 (substituting the actual steering position into the final target steering position) and when the steering is performed to the upper limit steering amount as indicated by ALT2. (The upper limit steering amount is substituted for the final target steering position). Which of ALT1 and ALT2 processing is to be performed can be defined in advance by a program.

In step S6, an upper limit steering speed which is an upper limit value of the steering speed allowable in the automatic steering is calculated. This upper limit steering speed is a basic value, and in the same manner as the upper limit steering amount, a range in which the vehicle does not lose stability is determined in advance by experiments or the like using the vehicle speed as a parameter, and is previously stored in the ROM 24 shown in FIG. Shall be.

The portion shown in black in the graph outside the frame of step S6 is the steering speed regulation region, and the regulation region is widened in proportion to the vehicle speed. This means that the upper limit steering speed is inversely proportional to the vehicle speed. In step S7, the upper limit steering amount is corrected by multiplying the basic value of the upper limit steering speed obtained in step S6 by a correction coefficient K3 according to the vehicle wiper operation status.

The correction coefficient K3 takes a value as shown in the graph outside the frame of step S7.
It is assumed that the information is stored in the ROM 24 in advance in the same manner as described above. Operation corresponding to the embodiment (2) : FIG. 3 In the embodiment (2), the processes of steps S1 to S7 are performed in the above-described embodiment.
This is performed in the same manner as (1). However, outside-vehicle temperature information is read instead of or in addition to the wiper operation information in step S1 of the embodiment (1).

Further, the correction coefficients K2 and K4 used in steps S3 and S7 take values obtained by experiments and the like as values equal to or less than "1" as shown in the graphs outside the frames of steps S3 and S7, respectively. And, like the correction coefficients K1 and K3,
It shall be stored in ROM24. That is, the correction coefficient K
2 and K4 are "1" when the temperature outside the vehicle is zero degree
And below zero the value is less than "1".

When the embodiment (2) has a configuration in which the vehicle temperature sensor 8 is provided instead of the vehicle wiper switch 7 in the embodiment (1), the correction coefficient K1 is set in steps S3 and S7.
Correction coefficients K2 and K4 may be used instead of and K3.
Further, when the embodiment (2) has a configuration in which the vehicle temperature sensor 8 is provided in addition to the vehicle wiper switch 7 in the embodiment (1),
In steps S3 and S7, the correction coefficients K1 and K3 respectively
May be used in combination with the correction coefficients K2 and K4.

Operation corresponding to the embodiment (3): FIG. 4 The processing flow in the case of the embodiment (3) shown in FIG . 2 is the same as that of FIG. 3 for the embodiment (1), as shown in FIG. Steps
S1 to S7 are executed. However, in step S1, road surface information is input instead of vehicle wiper operation information. In step S3, the basic value of the upper limit steering amount calculated in step S2 is multiplied by a correction coefficient K5 based on road surface information. As shown in the drawing, the correction coefficient K5 is "1" when the road surface information is "dry" outside the frame of step S3, and takes a smaller value in the order of "wet" and "freeze".

Further, in step S7, the basic value of the upper limit steering speed calculated in step S6 is multiplied by a correction coefficient K6 based on road surface information. As shown in the figure, the correction coefficient K6 is "1" when the road surface information is "dry", and takes a smaller value in the order of "wet" and "freeze" as shown in the figure outside the frame of step S7. It is.

The correction coefficients K5 and K6 are also the same as those described above.
It is assumed that it is stored in the ROM 24 in FIG. 2 in advance similarly to K1 to K4. Operations Common to Embodiments (1) to (3): FIG. 5 Next, steps S8 to S19, which are processes common to the embodiments (1) to (3), will be described with reference to FIG.

In step S8 of the figure, it is determined whether or not the target steering speed input in step S1 is within the regulation range. Similarly to the case of the steering amount, the regulation range of the steering speed after the correction in step S7 is wider than the regulation range based on the basic value of the steering speed. If the vehicle is not in the restricted area, the process proceeds to step S10. If the vehicle is in the restricted area, the target steering speed is changed in step S9.

The process in step S9 is performed when the current actual steering position is held as indicated by ALT1 (when the target steering speed is set to 0
), And when steering at the upper limit steering speed as indicated by ALT2 (substituting the upper limit steering speed into the target steering speed)
Can be considered. Which of ALT1 and ALT2 is to be performed can be defined in advance by a program as in step S5.

In step S10, in order to control the steering actuator 4, the actual steering position is compared with the final target steering position. When step S5 in FIG. 3 or 4 is being executed, the final target steering position is different from the input value in step S1. If the actual steering position is equal to the final target steering position, the steering has already been completed. Therefore, in step S11, the steering actuator 4 is controlled to maintain the actual steering position, and the process ends.

When the actual steering position <the final target steering position,
Right turning is performed according to steps S12 to S15. First, in step S12, the latest target steering position is calculated by adding the target steering speed to the current actual steering position. As described above, since the target steering speed is the amount of change in the actual steering position per unit time, it can be added to the actual steering position.

In step S13, the target steering position calculated in step S12 is compared with the final target steering position. Only when target steering position> final target steering position, step S14 is executed.
Substitutes the final target steering position into the target steering position. In step S15, the steering actuator 4 is controlled so as to turn right so that the actual steering position becomes the target steering position, and the process ends.

If the actual steering position> the final target steering position, the left steering is performed according to steps S16 to S19. First, in step S16, the latest target steering position is calculated by subtracting the target steering speed from the current actual steering position. In step S17, the target steering position calculated in step S16 is compared with the final target steering position, and only when target steering position <final target steering position, the final target steering position is substituted for the target steering position in step S18. In step S19, the steering actuator 4 is controlled so as to turn left so that the actual steering position becomes the target steering position, and the process ends.

The means for realizing the control of steps S2 to S7 shown in FIGS. 3 and 4 are incorporated in the steering position / steering speed calculation unit 1 in FIGS. It is also possible to configure such that a final target steering position equal to or less than the upper limit steering amount and a target steering speed equal to or less than the upper limit steering speed are input.

In the above embodiments (1) and (2), examples in which the vehicle wiper switch 7, the temperature sensor outside the vehicle 8, the receiver 9, and the antenna 10 are used as means for detecting a decrease in friction coefficient are shown. However, the present invention is not limited to this. For example, JP 05-85339, JP 05-86926, JP 05-3
It is also possible to detect the coefficient of friction using the method described in Japanese Patent No. 46394,
It can also be detected by the method described in JP-A-327542.

Further, for road surface information such as rain, snow, freezing, etc., it is possible to use road-vehicle communication described in Japanese Patent Application Laid-Open No. 08-055300.

[0060]

As described above, according to the present invention,
In an automatic steering device that steers a steered wheel of a vehicle via a steering actuator based on an electric steering command, an amount of change in a steered wheel or an actual steering position of the steering actuator per unit time is set as a steering speed, and the steered wheel or the steering wheel is steered. When the difference between the neutral position of the actuator and the actual steering position is used as the steering amount, an allowable steering speed and / or an upper limit value of the steering amount is set to an upper limit steering speed and / or an allowable upper limit of the steering amount in the memory so as to decrease as the vehicle speed increases. The maximum steering amount is previously associated with the vehicle speed,
The steering control means corrects the upper limit steering amount and / or the upper limit steering amount obtained by referring to the memory from the vehicle speed detected by the vehicle speed sensor in accordance with the detection result of the friction coefficient decrease sensor, and based on the steering command. Since the steering speed and / or the steering amount is controlled so as to be equal to or less than the corrected upper limit steering speed and / or upper limit steering amount, the safety of the steering control particularly at the time of high-speed running is improved and the road surface is improved. It is possible to increase the safety of the steering control according to the situation.

[Brief description of the drawings]

FIG. 1 shows embodiments (1) and (2) of an automatic steering device according to the present invention.
FIG.

FIG. 2 is a block diagram showing an embodiment (3) of the automatic steering device according to the present invention.

FIG. 3 is an embodiment (1) and (2) of an automatic steering device according to the present invention.
FIG. 6 is a flowchart illustrating a steering control operation corresponding to FIG.

FIG. 4 is a flowchart illustrating a steering control operation corresponding to the embodiment (3) of the automatic steering device according to the present invention.

FIG. 5 is a flowchart following FIG. 3 and FIG. 4, illustrating a steering control operation of the automatic steering device according to the present invention.

[Explanation of symbols]

 1 Steering position / steering speed calculation unit 2 Steering control device 3 Vehicle speed sensor 4 Steering actuator 5 Actual steering position sensor 6 Steering wheel 7 Vehicle wiper switch 8 Outside temperature sensor 9 Receiver 10 Antenna 11 Traveling road detecting unit 12 Own vehicle condition detecting unit 13 Travel pattern determination unit 14 Target travel locus calculation unit 15 Steering command value calculation unit 21 Input unit 22 CPU 23 RAM 24 ROM 25 Output unit 26 Power supply unit In the figures, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) B62D 113: 00 B62D 113: 00 117: 00 117: 00 137: 00 137: 00 F-term (Reference) 3D032 CC05 CC20 DA03 DA09 DA23 DA73 DA82 DA88 DB11 DD01 EC34 5H301 AA01 AA10 BB20 GG14 HH01

Claims (10)

[Claims] An automatic steering device for steering a steered wheel of a vehicle via a steering actuator based on an electric steering command, a friction coefficient reduction sensor detecting a decrease in a friction coefficient of a road surface, a vehicle speed detecting a vehicle speed. A sensor, an actual steering position sensor for detecting the actual steering position of the steered wheel or the steering actuator, and, when the amount of change in the actual steering position per unit time is used as the steering speed, it is permissible as the vehicle speed increases. A memory in which the vehicle speed and the upper limit steering speed are associated in advance so that the upper limit steering speed, which is the upper limit value of the steering speed, is reduced; and the upper limit steering speed obtained by referring to the memory from the vehicle speed is determined by the friction coefficient A steering control means for correcting in accordance with the detection result of the lowering sensor, and controlling the steering speed based on the steering command so as to be equal to or less than the corrected upper limit steering speed. apparatus. 2. The vehicle according to claim 1, wherein when the difference between the neutral position of the steered wheel or the steering actuator and the actual steering position is used as the steering amount, the memory stores the vehicle speed instead of the upper limit steering speed. The vehicle speed and the upper limit steering amount are associated in advance so that the upper limit steering amount, which is the upper limit value of the allowable steering amount, becomes smaller, and the steering control means refers to the memory based on the vehicle speed. Automatic steering, wherein the obtained upper limit steering amount is corrected in accordance with the detection result of the friction coefficient lowering sensor, and the steering amount based on the steering command is controlled to be equal to or less than the corrected upper limit steering amount. apparatus. 3. The vehicle according to claim 1, wherein when the difference between the neutral position of the steered wheel or the steering actuator and the actual steering position is used as a steering amount, the memory is configured to increase the vehicle speed in addition to the upper limit steering speed. The vehicle speed and the upper limit steering amount are associated in advance so that the upper limit steering amount, which is the upper limit value of the allowable steering amount, becomes smaller, and the steering control means refers to the memory based on the vehicle speed. The obtained upper limit steering speed and the upper limit steering amount are corrected according to the detection result of the friction coefficient lowering sensor, and the steering speed and the steering amount based on the steering command become equal to or less than the corrected upper limit steering speed and the upper limit steering amount. An automatic steering device characterized by performing control as follows. 4. The automatic steering apparatus according to claim 1, wherein the friction coefficient decrease sensor detects the decrease in the friction coefficient by operating a wiper device mounted on the vehicle. 5. The automatic steering apparatus according to claim 1, wherein the friction coefficient reduction sensor detects the reduction in the friction coefficient by an outside air temperature sensor mounted on a vehicle. 6. The friction coefficient reduction sensor according to claim 1, further comprising a communication unit configured to receive road surface information provided from a road surface information providing device installed on a road side. An automatic steering device, wherein the automatic steering device is detected based on the road surface information. 7. The steering control device according to claim 1, wherein when the steering speed based on the steering command exceeds the corrected upper limit steering speed, the steering control means controls to maintain a current actual steering position. An automatic steering device characterized by the following. 8. The steering system according to claim 1, wherein when the steering speed based on the steering command exceeds the corrected upper limit steering speed, the steering means controls to perform steering at the corrected upper limit steering speed. An automatic steering device characterized by the above-mentioned. 9. The steering control device according to claim 2, wherein when the steering amount based on the steering command exceeds the corrected upper limit steering amount, the steering control means controls to maintain a current actual steering position. An automatic steering device characterized by the following. 10. The method according to claim 2 or 3, wherein when the steering amount based on the steering command exceeds the corrected upper limit steering amount, the steering means controls to perform steering with the upper limit steering amount. An automatic steering device.