WO2016148112A1

WO2016148112A1 - Rear wheel steering control system

Info

Publication number: WO2016148112A1
Application number: PCT/JP2016/058032
Authority: WO
Inventors: 幸宏西尾; 康寛松永; 元広内山
Original assignee: Ntn株式会社
Priority date: 2015-03-16
Filing date: 2016-03-14
Publication date: 2016-09-22
Also published as: JP6523720B2; JP2016172471A

Abstract

In the present invention, a rear wheel steering control device which performs independent steering of left and right rear wheels controls a rear wheel steering device for independently steering the left and right rear wheels and has a pair of electronic control devices (13L, 13R) for respectively controlling a pair of left and right actuators (14L, 14R) of the rear wheel steering device (12). The rear wheel steering control system is provided with: the rear wheel steering control device; a connection switching unit (31) for alternately switching the connections of the steering motors (25L, 25R), rotation angle sensors (26L, 26R), and absolute position detectors (27L, 27R) of the pair of actuators (14L, 14R) to the pair of electronic control devices (13L, 13R); an abnormality determination part (32) for detecting an occurrence of abnormality in either one of the pair of electronic control devices (13L, 13R); and an abnormality handling control part (33) which, when the occurrence of an abnormality is detected, causes the connection switching unit (31) to perform the switching operation.

Description

Rear wheel steering control system

Related applications

This application claims the priority of Japanese Patent Application No. 2015-052439 filed on March 16, 2015, and is incorporated herein by reference in its entirety.

This invention relates to a rear wheel steering control system equipped in a vehicle such as an automobile.

Conventionally, a rear wheel steering device that steers rear wheels in addition to front wheel steering is known for the purpose of achieving stable running performance of a vehicle. The control device or control system of the rear wheel steering device has a built-in microcomputer, determines the control amount of the appropriate steering angle and toe angle from the detection values of various sensor groups for constantly monitoring the state of the vehicle, The actuator for turning is driven. The rear wheel steering device has an important function that affects the running performance of the vehicle, and estimates the optimum steering angle in accordance with the state of the vehicle and the road surface condition and performs vehicle stabilization control. Therefore, when an abnormality occurs in the system including the rear wheel steering device, it is desired to detect the abnormality reliably and maintain the safety performance as much as possible.

The following technology has been proposed as a countermeasure for avoiding unstable behavior of the vehicle in the event of an abnormality caused by a system related to a control device that independently controls the left and right of the rear wheels. For example, there is a vehicle equipped with a rear wheel steering mechanism that includes a vehicle behavior stabilization control system for stabilizing the behavior of the vehicle in order to prevent a decrease in vehicle running stability when the rear wheel steering system is abnormal. In this vehicle, when an abnormality occurs in the rear wheel steering control (toe angle cannot be changed, cannot be detected, etc.), particularly in the toe-out state, an abnormality of the rear wheel steering device is detected to control vehicle behavior stabilization. The vehicle behavior is stabilized by turning on the system (Patent Document 1).

Japanese Patent No. 5320286

In Patent Document 1, it is limited to the occurrence of an abnormality on the system side. For example, when an abnormality occurs in a toe-out state, control is performed to stabilize the behavior of the vehicle, and unstable behavior can be avoided. it can. However, the stability of the behavior of the vehicle is greatly reduced compared to the normal time.

An object of the present invention is that in a rear-wheel steering control device that independently steers left and right rear wheels of a vehicle, either the left or right steering control is disabled due to an abnormality of an electronic control device that controls an actuator In some cases, a rear wheel steering control system that prevents the behavior of the vehicle from becoming unstable is provided.

Hereinafter, in order to facilitate understanding, the present invention will be described with reference to the reference numerals of the embodiments for convenience.

The rear wheel steering control system 100 of the present invention includes a rear wheel steering control device 13 that controls a rear wheel steering device 12 that can control the steering angle and the toe angle of the

rear wheels

10 and 11 of the vehicle,
The rear wheel steering device 12 includes a pair of

actuators

14L and 14R that independently steer the left and right

rear wheels

10 and 11, respectively. The

actuators

14L and 14R include

steering motors

25L and 25R, Absolute position detection capable of detecting the absolute positions of the

rotation angle detectors

26L, 26R for detecting the rotation angle of the

steering motors

25L, 25R and the output portions of the

actuators

14L, 14R driven by the

steering motors

25L, 25R. 27L, 27R,
The rear wheel steering control device 13 has a pair of

electronic control devices

13L and 13R for controlling the pair of

actuators

14L and 14R, respectively.
The rear wheel steering control system
The

steering motors

25L and 25R, the

rotation angle detectors

26L and 26R, and the

absolute position detectors

27L and 27R that constitute the pair of

actuators

14L and 14R, respectively, and the pair of

electronic control devices

13L and 13R are connected. A connection switching unit 31 that switches alternately;
An abnormality determination unit 32 that detects that an abnormality that prevents the

actuators

14L and 14R from being normally driven occurs in any one of the pair of

electronic control apparatuses

13L and 13R;
When the abnormality determination unit 32 detects that the abnormality has occurred in one of the

electronic control devices

13L and 13R, the actuator 14L that is normally connected to the

electronic control devices

13L and 13R in which the abnormality has been detected. , 14R, switching operation to the connection switching unit 31 so that the

steering motors

25L, 25R,

rotation angle detectors

26L, 26R, and

absolute position detectors

27L, 27R are connected to the other

electronic control devices

13L, 13R. And an abnormality handling control unit 33 that performs the above.

According to this configuration, when one of the corresponding left and right actuators cannot be steered due to an abnormality in one of the

electronic controllers

13L and 13R that control the

actuators

14L and 14R, the other

electronic controller

13L , 13R and the left and

right actuators

14L or 14R are connected to each other. Therefore, it is possible to control the steering of the

actuators

14L and 14R on the side where the steering control is disabled, and to prevent the behavior of the vehicle from becoming unstable.

In this invention, the abnormality response control unit 33 switches to the connection switching unit 31 when the abnormality determination unit 32 detects that the abnormality has occurred in any one of the

electronic control devices

13L and 13R. The operation command and the steering command to each of the

actuators

14L and 14R may be performed according to a predetermined rule. When switching is made so that the other normal

electronic control device

13L or 13R and both the left and

right actuators

14L and 14R are connected when an abnormality occurs, the left and right

rear wheels

10 and 11 perform the same turning operation. However, when the connection is switched as described above, by giving a predetermined steering command, the appropriate

rear wheels

10, 11 can be steered, and the behavior of the vehicle is Instability can be prevented even better.

The abnormality response control unit 33 instructs the connection switching unit 31 to perform a predetermined switching operation when the abnormality determination unit 32 detects that the abnormality has occurred in any one of the

electronic control devices

13L and 13R. And a command for driving the

actuators

14L and 14R on both sides to return to the neutral position of the steering may be given. When one of the left and right steering control is disabled due to an abnormality in one of the

electronic control devices

13L and 13R, the other

electronic control device

13L and 13R and the left and

right actuators

14L and 14R are connected. When switched, the steering control can be performed for the

actuators

14L and 14R that are disabled to perform the steering control. However, since the time for connection with the

electronic control devices

13L and 13R is limited, the sufficient rear wheel steering control cannot be performed. There is a case. If the left and

right steering actuators

14L and 14R are steered to the neutral position, free rear wheel steering cannot be performed, but it is possible to safely prevent the behavior of the vehicle from becoming unstable. In this specification, the “predetermined switching operation command” may be an arbitrarily determined switching operation command. For example, the switching operation command may be switched alternately at regular intervals, or temporarily switched. Thereafter, the original connection state may be restored.

The abnormality response control unit 33 performs a predetermined switching operation to the connection switching unit 31 when the abnormality determination unit 32 detects that the abnormality has occurred in any one of the

electronic control devices

13L and 13R. The

rear wheels

10 and 11 on the inner wheel side of the vehicle turning are kept in a neutral position, and only the

rear wheels

10 and 11 on the outer wheel side of the turning drive are steered. The structure which gives the instruction | command to perform may be sufficient. Thus, when only the

rear wheels

10 and 11 on the outer wheel side are steered while the

rear wheels

10 and 11 on the inner wheel side are held in the neutral position, Under the condition that an abnormality has occurred in one of the

electronic control devices

13L and 13R, the function of rear wheel steering can be kept as much as possible. Particularly, by turning the rear wheel outer wheel side, the vehicle behavior stability can be improved as compared with the case where the rear wheel outer wheel is in the neutral position. In this way, it is possible to prevent the behavior of the vehicle from becoming unstable and to further improve the vehicle behavior stability.

When the abnormality determination unit 32 detects that the abnormality has occurred in any of the

electronic control devices

13L and 13R, the abnormality response control unit 33 uses the connection switching unit 31 to detect the abnormality at the initial stage. While switching the connection between the

actuators

14L and 14R and the

electronic control units

13L and 13R at predetermined time intervals, the rear wheel on the inner wheel side of the turning traveling of the vehicle is gradually moved to the neutral position, and at the same time the turning traveling is performed. You may make it perform control which moves the rear wheel which becomes an outer ring | wheel side to a predetermined angle. In this manner, the inner ring side is gradually moved to the neutral position while the connection between the

actuators

14L, 14R and the

electronic control units

13L, 13R is switched every predetermined time, and at the same time, the outer ring side is moved to a predetermined angle. In this case, the function of the rear wheel steering can be left as safely as possible under the condition that an abnormality has occurred in one of the

electronic control units

13L and 13R while preventing the behavior of the vehicle from becoming unstable. Also in this case, in particular, by turning the rear wheel outer wheel side, the vehicle behavior stability can be enhanced as compared with the case where the rear wheel is in the neutral position. In this way, it is possible to prevent the behavior of the vehicle from becoming unstable and to further improve the vehicle behavior stability.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the invention.

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.

It is a schematic explanatory drawing of the motor vehicle carrying the rear-wheel steering apparatus which applies the rear-wheel steering control system which concerns on one Embodiment of this invention. It is a block diagram of a conceptual composition of the same rear wheel steering control system.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory diagram of a vehicle equipped with a rear wheel steering device and a rear wheel steering control device to which a rear wheel steering control system 100 according to an embodiment is applied. The left and right

front wheels

2 and 3 of the vehicle 1 that is an automobile are steered left and right by transmitting the turning angle of the steering wheel 4 to the front wheel turning device 5 that is a main turning device. The front wheel steering device 5 includes, for example, a rack and pinion. The outputs of the steering angle sensor 6, the vehicle speed sensor 7, and the yaw rate sensor 8 provided for the steered shaft of the steering wheel 4 are input to the electronic control unit 9. This electronic control unit 9 is a main control unit that performs overall control and overall control of the automobile 1 and is generally abbreviated as ECU (Electronic Control Unit).

The left and right

rear wheels

10 and 11 are connected to a rear wheel steering device 12 fixed to a chassis (vehicle body) (not shown) via knuckle arms Na and Nb corresponding to the tie rods connected to the rear wheel steering device 12. Steered. The rear wheel steering device 12 can steer the left and right

rear wheels

10 and 11 independently by a pair of steering motor (left) 25L and steering motor (right) 25R. Regarding the turning angles of the

rear wheels

10 and 11, the target turning angles determined by the electronic control unit 9 according to the input of travel information of the automobile 1 such as the steering angle sensor 6, the vehicle speed sensor 7, and the yaw rate sensor 8 are the same. And received by the rear wheel steering control device 13. The rear wheel steering control device 13 controls the left and right

rear wheels

10 and 11 independently of each other.

The rear wheel turning device 12 is provided with an actuator for turning the

rear wheels

10 and 11 in the same phase or in the opposite phase with respect to the front wheel turning angle. For example, this actuator is a linear motion actuator composed of a slide screw without reverse input or a ball screw with a reverse input prevention mechanism, and a nut to be screwed to the nut is connected to the turning motor 25L via a speed reducer. , 25R, and this rotation is converted into a linear motion of the output part of the actuator. This direct acting actuator is composed of a first actuator 14L and a second actuator 14R in order to drive the left and right

rear wheels

10, 11 independently. The first actuator 14L is a drive mechanism that steers the left rear wheel 10, and the second actuator 14R is a drive mechanism that steers the right rear wheel 11. In the following, since the first and

second actuators

14L and 14R have the same configuration, only one of the

actuators

14L or 14R will be described and the description of the other one may be omitted unless particularly necessary. .

FIG. 2 is a block diagram of a conceptual configuration of a rear wheel steering control system 100 including a rear wheel steering control device 13 that controls the rear wheel steering device 12 (FIG. 1) having the above-described configuration. The rear wheel steering control device 13 is a pair of electronic control devices that independently control the first and

second actuators

14L and 14R that respectively steer the left and right rear wheels 10 and 11 (FIG. 1). 13L, 13R. These

electronic control devices

13L and 13R are control devices having the same configuration. For this reason, in the following description, only the first electronic control device 13L will be described, and description of the second electronic control device 13R may be omitted. In addition, for the steering motor (left) 25L, the rotation angle detector 26L, and the absolute position detector 27L, which are the components of the first actuator 14L, the second actuator 14R has similar components, The reference numerals for the corresponding components are the same in the numerals, but the last L and R are changed.

The connection switching unit 31 indicates the connection relationship between the

motor driving units

20L and 20R and the steered motor (left) 25L and the steered motor (right) 25R, and further includes input I /

F units

18L and 18R and a rotation angle detector. 26L, 26R, and

absolute position detectors

27L, 27R are connected to each other. The connection switching unit 31 normally connects the motor drive unit 20L to the steered motor (left) 25L, and connects the input I / F unit 18L to the rotation angle detection unit 26L and the absolute position detector 27L. The motor drive unit 20R is normally connected to a turning motor (right) 25R, and the input I / F unit 18R is connected to the rotation angle detection unit 26R and the absolute position detector 27R.

The connection switching unit 31 can switch the connection between the electronic control device 13L and the first actuator 14L and the connection between the electronic control device 13R and the second actuator 14R according to a command from the electronic control unit 9. Therefore, if necessary, the motor drive unit 20L is connected to the steering motor (right) 25R, the input I / F unit 18L is connected to the rotation angle detection unit 26R and the absolute position detector 27R, and the motor drive unit 20R is rotated. The connection switching unit 31 can be switched to connect to the rudder motor (left) 25L and connect the input I / F unit 18R to the rotation angle detection unit 26L and the absolute position detector 27L.

The electronic control unit 13L includes a microprocessor 16L, an input interface unit 17L for command-side input signals obtained from the electronic control unit 9, which is a higher-level control unit, and a detection-side input signal obtained from the first actuator 14L. It has an input interface unit 18L, an output interface unit 19L, and a motor drive unit 20L. The command-side and detection-side

input interface units

17L and 18L may be electronic elements in different packages or separate electronic elements in one package.

The target value of the rear wheel turning angle determined by the electronic control unit 9 is transmitted to the microprocessor 16L via the input interface unit 17L on the command side, and is input to the motor control target value calculation unit 22L in the microprocessor 16L. . In the microprocessor 16L, in order to execute the control of the steering motor (left) 25L, the result calculated by the motor control target value calculation unit 22L (in this embodiment, for example, the steering motor calculated from the steering angle ( Left) A motor drive command based on 25L) is transmitted to the motor drive unit 20L via the output interface unit 19L. Specifically, the motor control target value calculation unit 22L is a predetermined conversion function stored in an LUT (Look Up Table) realized by software or hardware, or a software library (Library) or an equivalent thereof. Hardware that uses hardware etc. (hereinafter referred to as “realization model”), receives the input of the target value of the aforementioned rear wheel turning angle, and calculates and outputs the command value that is the source of the motor drive command It is composed of software functions on a circuit or a processor (not shown).

For example, when a brushless motor is used as the steering motor (left) 25L, control is based on torque (current), speed, and position, and the control target of this control system is the position (steering angle). A control system (not shown) mounted on the microprocessor 16L is a composite control system that constitutes a speed control system and a position control system above the current control system. Therefore, the motor drive command value is determined based on the calculation result calculated by the command from the electronic control unit 9 and the feedback value such as the motor current detection value and the rotation angle detection value obtained from the motor current detection unit 24L. Controlled to reach the corner.

The absolute position detector 27L monitors the absolute position of the first actuator 14L. The absolute position corresponds to the turning angle of the

wheels

10 and 11, and is detected when the power is turned on, for example, when an ignition (not shown) of the vehicle is turned on. After that, the position is controlled with the rotation angle obtained from the rotation angle detector 26L with the detected absolute position as a reference (reference position). These control systems are mounted on the microprocessor 16 so as to be controlled by, for example, software calculation.

Next, problems that can be solved with the above configuration and countermeasures for them will be described. For example, if a problem occurs in any of the motor drive unit 20L, the output I / F unit 19L, the motor control target value calculation unit 22L, the input I / F unit 18L, and the like inside the electronic control device 13L while the vehicle is running, There is a possibility that the rear wheel 10 steers to an unintended angle or does not steer. As a result, the vehicle heads in a direction not intended by the driver.

As this countermeasure, the rear wheel steering control system 100 of this embodiment is provided with the connection switching unit 31 and an abnormality coping unit 34. The abnormality handling unit 34 is provided in the electronic control unit 9, for example. The abnormality handling unit 34 includes an abnormality determination unit 32 and an abnormality handling control unit 33. The abnormality determination unit 32 detects that an abnormality that prevents the

corresponding actuators

14L and 14R from being normally driven occurs in any one of the pair of

electronic control devices

13L and 13R. Specifically, the abnormality determination unit 32 uses the above-described realization model or comparison function or hardware equivalent thereto, signals at predetermined locations of the

electronic control devices

13L and 13R, and the

electronic control devices

13L and 13R. Software on a hardware circuit or processor (not shown) that can make an abnormality determination by comparing with other portions or predetermined signals in the electronic control unit 9 or the

actuators

14L and 14R and output the determination result It consists of wear functions.

When the abnormality determination control unit 32 detects that the abnormality cannot be normally driven in any one of the

electronic control devices

13L and 13R, the abnormality determination control unit 33 generates the abnormality as described above. The

steering motor

25L or 25R, the

rotation angle sensor

26L or 26R, and the

absolute position detector

27L or 27R in the

actuator

14L or 14R normally connected to the

electronic control device

13L or 13R in which It is means for causing the connection switching unit 31 to perform a switching operation so as to be connected to the

electronic control device

13L or 13R. Specifically, the abnormality handling control unit 33 is provided with a switching operation command to the connection switching unit 31 and a steering command to each of the

actuators

14L and 14R using the above-described embodiment model. A hardware circuit or a software function on a processor (not shown) is performed as follows according to the rules. The defined rules may be arbitrarily defined regardless of the contents thereof, but a plurality of examples will be described later.

Specifically, the abnormality response control unit 33 determines whether or not the first actuator 14L is normal when the abnormality determination unit 32 detects, for example, the abnormality that cannot be normally driven by the electronic control unit 13L. For example, the abnormality determination unit 32 instructs the connection switching unit 31 to connect the electronic control device 13R to the first actuator 14L. Thereby, the connection switching unit 31 connects the motor drive unit 20L to the steered motor (right) 25R, and connects the input I / F unit 18L to the rotation angle detection unit 26R and the absolute position detector 27R. In addition, the motor drive unit 20R is connected to the steering motor (left) 25L, and the input I / F unit 18R is connected to the rotation angle detection unit 26L and the absolute position detector 27L. At this time, the function of the electronic control unit 13L is invalidated by turning off the power to one electronic control unit 13L. If the first actuator 14L is driven from the electronic control unit 13R after the connection is switched, it can be determined whether the actuator 14L is normal from the position of the first actuator 14L, the current value of the steering motor (left) 25L, and the like. If an abnormality of the electronic control device 13R opposite to the above is detected, it is determined whether the same control as described above is reversed left or right, that is, whether the second actuator 14R is normal.

When the first actuator 14L is normal, the abnormality response control unit 33 determines that the rear wheel steering control method is based on the control of steering both the inner and outer wheels at normal times to the respective target steering angles, and maintains the rear wheel inner side at the neutral position. Then, the control is switched to “control for turning to the target rudder angle only on the rear wheel outer side”. Here, the inner ring side and the outer ring side refer to the inner side and the outer side with respect to the turning direction.

This “control for keeping the inner side of the rear wheel in a neutral position and turning the rear wheel only to the target rudder angle” will be described. The abnormality response control unit 33 can determine from the turning angle of the steering wheel 4 which of the first actuator 14L and the second actuator 14R drives the inner wheel in turning. Here, at the time of occurrence of abnormality, the first actuator 14L is set to the inner wheel side (that is, the steering direction to the left front), and the first actuator 14L is not in the neutral position of the rear wheel steering device 12. The abnormality response control unit 33 instructs the connection switching unit 31 to switch the connection, and switches the connection between the electronic control device 13R and the first actuator 14L or the second actuator 14R via the electronic control device 13R. Both

actuators

14L and 14R are controlled.

In an initial stage where an abnormality has occurred during turning, the abnormality response control unit 33 first moves the first actuator 14L to the neutral position when the electronic control device 13R is connected to the first actuator 14L side which is the inner ring side. Control to move. The abnormality response control unit 33 controls the electronic control device 13R to move to a predetermined turning position (that is, to the target steering angle) when the electronic control device 13R is connected to the second actuator 14R on the outer wheel side.

At this time, the connection switching unit 31 switches the connection between the electronic control device 13R and the first actuator 14L or the second actuator 14R alternately at predetermined time intervals, thereby gradually targeting the rear wheels that are the inner ring and the outer ring. Turn to position. The predetermined time for alternately switching may be set arbitrarily, but for example, is a short time in milliseconds. When the first actuator 14L on the inner ring side reaches the neutral position, the switching control of the alternate switching of the inner ring and outer ring at every predetermined time by the connection switching unit 31 is stopped, and the electronic control unit 13R is turned to the second actuator 14R on the outer ring side. To control the steering of the outer wheel. When the mechanism for continuously holding the first actuator 14L in the neutral position is not provided, the alternate switching drive control is continued, and the electronic control unit 13R is changed to the first actuator 14L. You may perform control which continues hold | maintaining in the said neutral position.

Further, when the driver turns the steering wheel 4 in the reverse direction and the first actuator 14L is switched to the outer wheel side (that is, the steering direction to the right front), the electronic control unit 13R connects to the first actuator 14L. Thus, the connection switching unit 31 switches the connection, and the electronic control unit 13R steers the first actuator 14L on the outer wheel side. As described above, the electronic control device 13R is connected to the outer wheel side actuator in both the case of the left front steering and the right front steering, and the connection switching unit 31 performs the above-described alternate switching. When the steering angle of the steering wheel 4 is neutral, the connection switching unit 31 connects the electronic control device 13R to either one of the

actuators

14L and 14R.

The above-mentioned “control to turn the rear wheel to the target rudder angle only while keeping the rear wheel inside in the neutral position” steers the outer wheel that can further contribute to the steering, while reducing the computational load of the electronic control unit. From the above aspect, the inner ring is aimed to be held in a neutral position. Here, since the total cornering force of the rear wheels is smaller than in the case of steering with both normal wheels, the steering amount of the outer wheels may be made larger than usual in order to improve vehicle behavior stability.

The above method can prevent the behavior of the vehicle from becoming unstable when an abnormality occurs, and can improve the stability of the vehicle behavior as compared with the case where the rear wheel is in the neutral position. Even when a trouble occurs in the electronic control device 13R reversed to the left and right, the first and

second actuators

14L and 14R are controlled by the electronic control device 13L in the same manner as described above, except that the left and right are reversed. Take measures by

The connection switching unit 31 is connected to the electronic control device 13L and the first and

second actuators

14L and 14R when an abnormality occurs in the electronic control device 13L. It is not necessary to connect the two

actuators

14L and 14R. Similarly, while the electronic control device 13R is connected to the first and

second actuators

14L and 14R and controlled by the occurrence of an abnormality in the electronic control device 13R, the electronic control device 13R and the first and

second actuators

14L and 14R are controlled. It is not necessary to connect to. In other words, the connection switching unit 31 may not perform the alternate switching. Further, switching between the steered motor (left) 25L, the steered motor (right) 25R, and the

motor drive units

20L and 20R is based on the state in which the motor drive unit current is OFF (current value is zero) or the current value during normal operation. Is switched after setting the current value to a small predetermined value.

Next, another example of the rules of control performed by the abnormality response control unit 33 will be described. In this example, as in the above example, a case will be described in which an abnormality has occurred where the first electronic control unit 13L cannot be driven normally. First, similarly to the above example, it is determined whether the actuator 14L is normal. Thereafter, the abnormality handling control unit 33 controls as follows.

When the first actuator 14L is normal, the abnormality response control unit 33 of the electronic control unit 9 shifts to control for turning both the first actuator 14L and the second actuator 14R to the neutral position. That is, substantially the two rear wheels are not used for rear wheel steering.

The abnormality response control unit 33 instructs the connection switching unit 31 to switch the connection, and switches both the actuators via the electronic control unit 13R while switching between the electronic control unit 13R and the first actuator 14L or the second actuator 14R. 14L and 14R are steered to the neutral position. At this time, the connection switching unit 31 moves the inner ring and the outer ring little by little almost simultaneously by alternately switching the connection between the electronic control unit 13R and the first actuator 14L or the second actuator 14R at each predetermined time. To the neutral position. Regarding the movement of the first actuator 14L and the second actuator 14R to the neutral position, for example, the outer ring side, which is heavily loaded during turning, is first steered to the neutral position and then the inner ring side is steered to the neutral position. Both actuators may be moved in order.

Also by the above method, by turning the first actuator 14L and the second actuator 14R to the neutral position, it is possible to prevent the behavior of the vehicle 1 from becoming unstable when an abnormality occurs. In the example of this method, similarly to the first example, even when a malfunction occurs in the electronic control device 13R that is reversed to the left and right, the first operation from the electronic control device 13L is the same as described above, except that the left and right are reversed. Then, the

second actuators

14L and 14R are controlled to take countermeasures in the same manner.

The preferred embodiments for carrying out the present invention have been described based on the embodiments with reference to the drawings. However, those skilled in the art will understand various changes and modifications within the obvious scope by looking at the present specification. Would be easily assumed. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims, or equivalent meaning and scope.

DESCRIPTION OF SYMBOLS 1 ... Vehicle 5 ... Front wheel steering device 6 ... Steering angle sensor 9 ...

Electronic control unit

10, 11 ... Rear wheel 12 ... Rear wheel steering device 13 ... Rear wheel

steering control device

13L, 13R ...

Electronic control device

14L, 14R ...

Actuators

20L, 20R ...

motor drive units

24L, 24R ... motor

current detection units

25L, 25R ... steered

motors

26L, 26R ...

rotation angle detectors

27L, 27R ... absolute position detectors 31 ... connection switching unit 32 ... abnormality determination unit 33 ... Abnormality response control unit 34 ... Abnormality response unit 100 ... Rear wheel steering control system

Claims

A rear wheel steering control system including a rear wheel steering control device for controlling a rear wheel steering device capable of controlling a steering angle and a toe angle of a rear wheel of a vehicle,
The rear wheel steering device has a pair of actuators that respectively steer left and right rear wheels independently, and each of the actuators includes a steering motor and a rotation angle detector that detects a rotation angle of the steering motor. And an absolute position detector capable of detecting the absolute position of the output part of the actuator driven by the steering motor,
The rear wheel steering control device has a pair of electronic control devices that control the pair of actuators, respectively.
The rear wheel steering control system
A connection switching unit that alternately switches the connection between the steering motor, the rotation angle detector, and the absolute position detector that constitute each of the pair of actuators, and the pair of electronic control devices;
An abnormality determination unit that detects that an abnormality that prevents the actuator from being normally driven in any one of the pair of electronic control devices has occurred,
When the abnormality determination unit detects that the abnormality has occurred in any one of the electronic control devices, the steering motor and the rotation angle in the actuator that is normally connected to the electronic control device in which the abnormality has been detected. A rear wheel steering control system comprising: a detector; and an abnormality response control unit that causes the connection switching unit to perform a switching operation so that the absolute position detector is connected to the other electronic control unit.
2. The rear wheel steering control system according to claim 1, wherein when the abnormality determination unit detects that the abnormality has occurred in any one of the electronic control devices, the abnormality switching control unit A rear wheel steering control system that issues a command for switching to and a command for turning to each of the actuators according to a predetermined rule.
3. The rear wheel steering control system according to claim 2, wherein when the abnormality determination unit detects that the abnormality has occurred in any of the electronic control devices, the abnormality switching control unit A rear-wheel steering control system that gives a command to drive a predetermined switching operation to drive the actuators on both sides to return to the neutral position of the steering.
3. The rear wheel steering control system according to claim 2, wherein when the abnormality determination unit detects that the abnormality has occurred in any of the electronic control devices, the abnormality switching control unit A command to perform a predetermined switching operation is given to the vehicle, and the rear wheel on the inner wheel side of the turning traveling of the vehicle is kept in the neutral position, and only the rear wheel on the outer wheel side of the turning traveling is driven to be steered. Rear wheel steering control system that gives commands.
3. The rear wheel steering control system according to claim 2, wherein when the abnormality determination unit detects that the abnormality has occurred in any of the electronic control units, the abnormality occurrence initial stage is While the connection switching unit switches the connection between the actuator and the electronic control device at predetermined time intervals, the rear wheel on the inner wheel side of the turning traveling of the vehicle is gradually moved to the neutral position, and the turning traveling is performed at the same time. A rear-wheel steering control system that performs control to move the rear wheel on the outer wheel side to a predetermined angle.