JP2021091354A - Turning device - Google Patents

Abstract

To provide a stand-alone type turning device with high practicability.SOLUTION: A turning device 34, which is deployed in a vehicle equipped with a plurality of wheels 12 which can be turned and turns one of the plurality of wheels independently, is configured to comprise an actuator 36 having an electric motor 36a as a driving source and a controller that controls supply electric currents to the electric motor so that turning of the wheels in accordance with an operation amount of the electric motor can be achieved, and further is configured to enable the controller to detect a turning impossible phenomenon that the wheels cannot be turned although the electric motor is in operation, on the basis of the operation amount of the electric motor and a condition of variation of the supply electric currents to the electric motor. The turning device can detect the turning impossible phenomenon without detecting turning amounts of the wheels and deal with the detected turning impossible phenomenon.SELECTED DRAWING: Figure 1

Description

The present invention relates to a steering device that is deployed in a vehicle and steers wheels.

Recently, a steering device that is deployed in a vehicle having a plurality of wheels that can be steered and steers one of the plurality of wheels independently (hereinafter, may be referred to as a "stand-alone steering device"). ) Is being considered. For example, in the stand-alone steering device described in the following patent document, actuators having an electric motor as a drive source are provided for each of the left and right wheels so that the left and right wheels can be steered independently. Has been done. Then, in the stand-alone steering device described in the following patent document, when an abnormality occurs in one of the left and right actuators, the steering force due to the other is mechanically transmitted to the one in which the abnormality occurs. A fail-safe mechanism is provided.

Japanese Unexamined Patent Publication No. 2011-131777

In a stand-alone steering device, it is meaningful to detect its own malfunction. On the other hand, there are many types of defects, and by detecting a certain type of defect, the defect can be dealt with. That is, the practicality of the stand-alone steering device is improved by making it possible to detect a specific defect. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly practical stand-alone steering device.

In order to solve the above problems, the steering device of the present invention
A steering device that is deployed in a vehicle, each of which has a plurality of wheels that can be steered, and that steers one of the plurality of wheels independently.
It is equipped with an actuator having an electric motor as a drive source and a controller that controls the supply current to the electric motor to steer the wheels according to the operating amount of the electric motor.
The controller detects a non-steering phenomenon in which the wheels cannot be steered even though the electric motor is operating, based on the amount of operation of the electric motor and the state of change in the supply current to the electric motor. It is configured to do.

The unsteering phenomenon is, for example, a force acting on the wheels from the road surface in the direction in which the vehicle is going to go straight due to slippage between the components of the motion transmission mechanism between the electric motor and the steering knuckle, that is, self. This corresponds to a phenomenon in which the wheels cannot be steered by overcoming the alignment torque. The self-alignment torque increases as the amount of wheel steering increases, and the force required to overcome the self-alignment torque is proportional to the current (strictly speaking, electric power) supplied to the electric motor. Therefore, simply put, even if the electric motor is operated in an attempt to steer a wheel exceeding a certain steering amount due to the occurrence of the above-mentioned unsteering phenomenon, the wheel steering is maintained at that steering amount. At the same time, the supply current to the electric motor is maintained at a certain value. In other words, due to the occurrence of the unsteering phenomenon, a deviation occurs between the amount of steering of the wheels and the amount of operation of the electric motor. In the steering device of the present invention, the steering amount of the wheels is determined by the operating amount of such an electric motor and the state of change in the supply current to the electric motor (a concept including the fact that the supply current does not change). The above-mentioned non-steering phenomenon can be detected without detecting it. When the controller detects the non-steering phenomenon, for example, the controller can deal with the non-steering phenomenon, and the steering device of the present invention becomes highly practical.

Aspects of the invention

In the case where the non-steering phenomenon occurs when the steering amount of the wheel exceeds a certain steering amount as described above, in the steering device of the present invention, the steering non-steering phenomenon is caused by the controller. It can be configured to detect the phenomenon occurrence operation amount, which is the operation amount of the electric motor when it occurs.

Then, in the steering device of the present invention, when the controller reduces the steering amount of the wheels from the state in which the steering impossible phenomenon occurs, the reduction is performed based on the detected phenomenon occurrence operation amount. Is possible. Based on the amount of motion that occurs, the steering position during straight-ahead (hereinafter referred to as "the steering position") is eliminated while eliminating the discrepancy between the amount of steering of the wheels and the amount of operation of the electric motor that occur when the phenomenon of inability to steer occurs. It is possible to position the wheels at the "straight-ahead position").

Further, in the steering device of the present invention, the controller can be configured to prohibit the operation of the electric motor exceeding the amount of operation in which the phenomenon occurs. That is, the controller can be configured to prohibit the steering of the wheels beyond the position where the unsteering phenomenon occurs. When the non-steering phenomenon depends on the slip between the components of the motion transmission mechanism, the continuation of the non-steering phenomenon leads to the wear of these components to each other, and the amount of motion generated by the phenomenon gradually decreases. Eventually, it becomes almost impossible to steer the wheels. In other words, it will cause great damage to the steering device. Therefore, when the steering impossible phenomenon is detected, it is possible to avoid receiving a large damage to the steering device by limiting the steering of the wheels so that the steering impossible phenomenon does not occur thereafter.

Further, a steering system is constructed by providing the steering device of the present invention for each of a plurality of wheels, and the steering system is installed in the steering device provided for one of the plurality of wheels. When an unsteerable phenomenon occurs, a steering device provided for one or more of the other wheels in order to alleviate the shortage of the turning amount of the vehicle due to the unsteerable phenomenon. It may be configured to increase the operating amount of the electric motor included in the actuator of the above. According to this steering system, the insufficient turning amount of the vehicle caused by the unsteering phenomenon in the steering device provided on one wheel can be alleviated by increasing the steering amount of the other wheels. Is possible.

It is a perspective view which shows the wheel arrangement module for a vehicle which was configured including the steering device of an Example. It is a schematic diagram which shows the vehicle which the wheel arrangement module shown in FIG. 1 is mounted on each wheel. It is a schematic diagram for demonstrating the mechanism of the steering inability phenomenon which occurs in the steering apparatus of an Example. It is a graph which shows the relationship between the steering amount of a wheel, and the motor rotation amount of a steering motor, in order to explain the unsteering phenomenon. It is a schematic diagram for demonstrating the steering support which performs by increasing the steering amount of another wheel when the steering inability phenomenon occurs for one wheel. It is a flowchart of the wheel steering program executed in the steering apparatus of an Example. It is a flowchart of the subroutine executed in the wheel steering program of FIG.

Hereinafter, as a mode for carrying out the present invention, a steering device according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition to the following examples, the present invention will be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art, including the forms described in the section of [Aspects of the Invention]. be able to.

[A] Hard Configuration of Steering Device and Vehicle Wheel Arrangement Module The steering device of the embodiment is the vehicle wheel arrangement module 10 shown in FIG. 1 (hereinafter, may be simply referred to as “module 10”). It has been incorporated. The module 10 is a module for arranging the wheel 12b on which the tire 12a is mounted on the vehicle body. The wheel 12b itself can be considered as a wheel, but in the present embodiment, the wheel 12b on which the tire 12a is mounted is referred to as a wheel 12.

The module 10 has a wheel drive unit 14 as a wheel rotation drive device. The wheel drive unit 14 includes a housing 14a, an electric motor as a drive source built in the housing 14a, a speed reducer for reducing the rotation of the electric motor (both not shown), and an axle hub to which the wheels 12b are attached (FIG. Then it is hidden and cannot be seen). The wheel drive unit 14 is arranged inside the rim of the wheel 12b, and is a so-called in-wheel motor unit. Since it has a well-known structure, the description here is omitted.

The module 10 includes a MacPherson type suspension device (also referred to as a "MacPherson strut type"). In this suspension device, the housing 14a of the wheel drive unit 14 functions as a carrier that rotatably holds the wheels, in other words, the housing 14a functions as a steering knuckle in the steering device described later. Therefore, the suspension device includes a lower arm 16 which is a suspension arm, a housing 14a of the wheel drive unit 14, a shock absorber 18, and a suspension spring 20.

Since the suspension device itself has a general structure, the lower arm 16 has a so-called L-arm shape, and the base end portion is divided into two parts in the front-rear direction of the vehicle. At its base end, it is rotatably supported by a side member (not shown) of the vehicle body via the first bush 22 and the second bush 24 so as to be rotatable around the arm rotation axis L. The tip of the lower arm 16 can be rotated to the lower part of the housing 14a of the wheel drive unit 14 via a ball joint 26 for connecting an arm (hereinafter, may be referred to as “first joint 26”) which is a first joint. It is connected.

The lower end of the shock absorber 18 is fixedly supported by the housing 14a of the wheel drive unit 14, and the upper end is supported by the upper portion of the tire housing of the vehicle body via the upper support 28. The upper end of the suspension spring 20 is also supported by the upper part of the tire housing of the vehicle body via the upper support 28, and the lower end of the suspension spring 20 is supported by the lower support 18a provided in a flange shape on the shock absorber 18. ing. That is, the suspension spring 20 and the shock absorber 18 are arranged in parallel with each other between the lower arm 16 and the vehicle body.

The module 10 has a brake device, and the brake device is attached to the axle hub together with the wheel 12b and rotates together with the wheel 12, and the disc rotor 30 and the wheel drive unit 14 straddle the disc rotor 30. It is configured to include a brake caliper 32 held in the housing 14a. Although detailed description is omitted, the brake caliper 32 has a brake pad as a friction member and an electric motor, and the brake pad is pressed against the disc rotor 30 by the force of the electric motor to stop the rotation of the wheel 12. The brake device is an electric brake device that generates a braking force depending on a force generated by a so-called electric motor.

Further, the present module 10 has a steering device 34 which is an embodiment of the present invention. The steering device 34 is a single-wheel steering device for steering only one of the pair of left and right wheels 12, and is generally a housing 14a of the wheel drive unit 14 that functions as a steering knuckle as described above. (Hereinafter, when it is treated as a component of the steering device 34, it may be referred to as "steering knuckle 14a".) And the steering actuator 36 arranged on the lower arm 16 at a position close to the base end portion of the lower arm 16. And a tie rod 38 that connects the steering actuator 36 and the steering knuckle 14a.

The steering actuator 36 is rotated by rotation via a steering motor 36a, which is an electric motor as a drive source, a reduction gear 36b that reduces the rotation of the steering motor 36a, and a reduction gear 36b of the steering motor 36a. It is configured to include an actuator arm 36c that functions as a pitman arm. The base end portion of the tie rod 38 is connected to the actuator arm 36c via a ball joint 40 for connecting the base end portion of the rod, which is a second joint (hereinafter, may be referred to as “second joint 40”), and the tie rod 38 is connected. The tip portion is connected to the knuckle arm 14b of the steering knuckle 14a via a rod tip portion ball joint 42 (hereinafter, may be referred to as “third joint 42”) which is a third joint.

The suspension device is a McPherson type suspension device, and the line connecting the center of the upper support 28 and the center of the first joint 26 is the kingpin axis KP. By controlling the operation of the steering motor 36a, the steering actuator 36 rotates the steering knuckle 14a around the kingpin axis KP. That is, the wheels 12 are steered.

In the steering device 34, the steering actuator 36 is arranged on the lower arm 16. Therefore, the work of assembling the module 10 to the vehicle body can be easily performed. In short, the module 10 can be mounted on the vehicle by attaching the base end portion of the lower arm 16 to the side member of the vehicle body and attaching the upper support 28 to the upper part of the tire housing of the vehicle body. That is, the module 10 is considered to be a module having excellent mountability on a vehicle.

The module 10 can be arranged, for example, for each of the four front, rear, left, and right wheels 12 of the vehicle, as schematically shown in FIG. In this vehicle, when it comes to steering the wheels 12, each steering device 34 of the four modules 10 may be individually abbreviated as a steering electronic control unit (hereinafter, "steering ECU") which is a controller. , In the figure, it is shown as "S-ECU".) It is controlled by 50. Specifically, the steering ECU 50 controls the steering motor 36a of the steering device 34 of each module 10. Therefore, it can be considered that the steering device 34 is configured including the steering ECU 50. Incidentally, the steering ECU 50 is configured to include a computer having a CPU, ROM, RAM, etc., a drive circuit of the steering motor 36a, and the like.

It can be considered that the vehicle is equipped with a steering system including four steering devices 34 corresponding to the four wheels 12. The steering system is a so-called steer-by-wire type steering system, and has an operating device 52 for receiving a driver's steering operation as a component thereof. The operating device 52 has a steering wheel 54 as a steering operating member, a steering sensor 56 for detecting an operating angle which is a rotation angle of the steering wheel 54 as an operating amount of the steering operating member, and an operating reaction force on the steering wheel 54. And an operation electronic control unit which is a controller of the operation device 52 (hereinafter, may be abbreviated as "operation ECU", and is shown as "O-ECU" in the figure). Has 60 and. The steering ECU 50 and the operation ECU 60 are connected to a CAN (car area network or controllble area network) 62, and can communicate with each other via the CAN 62.

[B] Control of steering device
i) Basic control The steering ECU 50 of each steering device 34 obtains the operation angle of the steering wheel 54 based on the detection of the steering sensor 56, that is, the operation amount δ, from the operation ECU 60 via the CAN 62, and obtains the operation angle δ. Based on the operation amount δ, the target steering amount, which is the steering amount to be realized in the wheel 12 that is steered by itself, is determined. Since the steering amount of the wheels 12 and the operating amount of the steering motor 36a, that is, the motor rotation amount θ which is the rotation amount of the steering motor 36a, are in a predetermined ratio, they are actually set as the target steering amount. To determine the ^{target motor rotation amount θ *} , which is the motor rotation amount θ to be realized. Incidentally, the motor rotation amount θ is acquired by using a motor rotation angle sensor (for example, a resolver or the like) provided in the steering motor 36a for switching the energizing phase. The steering amount of the wheel 12 means a steering angle based on the position when the vehicle is in a straight-ahead state (hereinafter, may be referred to as a “reference position”), and the motor rotation amount θ is the wheel 12 Means the rotation angle of the steering motor 36a with reference to the rotation position when is the reference position (hereinafter, may be referred to as "reference rotation position").

In addition, this steering system also rolls two wheels 12 on the rear side (hereinafter, may be referred to as "rear wheel 12", and similarly, the two wheels 12 on the front side may be referred to as "front wheel 12"). In order to steer, in addition to steering the front wheels 12, the rear wheels 12 are also steered. That is, this steering system is a so-called four-wheel steering system. The target steering amount of the rear wheels 12 in this steering system may be determined in the same manner as a general four-wheel steering system based on, for example, the vehicle traveling speed v, the operating amount δ of the steering wheel 54, and the like. The detailed explanation in is omitted. The steering ECU 50 of each steering device 34 depends on which of the front, rear, left and right wheels 12 is the wheel 12 (hereinafter, may be referred to as "corresponding wheel 12") that itself controls steering. Based on the set determination rule, the target steering amount of the corresponding wheel 12, that is, the steering motor 36a that is controlled to steer the corresponding wheel 12 (hereinafter, may be referred to as "corresponding steering motor 36a"). Determine the target motor rotation amount θ ^* of.

The steering ECU 50 of each steering device 34 acquires the actual motor rotation amount θ, which is the actual motor rotation amount θ at the present time, based on the detection of the motor rotation angle sensor, and the actual motor with respect to the target motor rotation amount θ ^* . The motor rotation amount deviation Δθ, which is the deviation of the rotation amount θ, is calculated. Then, the supply current i, which is the current supplied to the steering motor 36a, is determined according to the feedback control method based on the motor rotation amount deviation Δθ, and the current i is supplied to the steering motor 36a. Since this method is general, the description of the method here is omitted.

A force for returning the wheel 12 to the reference position, that is, a self-alignment torque Tq, acts on the wheel 12 from the road surface, and the steering device 34, specifically, the speed reducer 36b of the steering device 34. The reverse efficiency is lower than the positive efficiency. From these facts, even when the same steering amount is realized, the process of increasing the steering amount of the wheel 12, the process of maintaining the steering amount, and the process of decreasing the steering amount. The supply current i is different from the above. By the way, in the process of increasing the steering amount of the wheel 12, the steering motor 36a needs to generate a torque sufficient to overcome the self-alignment torque Tq, while the self-alignment torque Tq is the self-alignment torque Tq of the wheel 12. It is a size that depends on the actual steering amount and the vehicle traveling speed v. Therefore, roughly speaking, in the process of increasing the steering amount of the wheel 12, a current i having a magnitude corresponding to the self-alignment torque Tq is supplied to the steering motor 36a.

ii) Unable to steer and control to deal with it In the steering device 34 of this embodiment, the wheel 12 cannot be steered even though the steering motor 36a is operating. Control is performed to deal with the unsteerable phenomenon. The non-steering phenomenon appears, for example, when slippage occurs between the components of the steering actuator 36. More specifically with reference to FIG. 3, for example, the steering actuator 36 has a structure in which the output shaft 36b1 of the speed reducer 36b is fitted into the hole 36c1 of the actuator arm 36c. In this structure, the rotation of the output shaft 36b1 is transmitted as the rotation of the actuator arm 36c by the frictional force between the outer peripheral surface 36b2 of the output shaft 36b1 and the inner peripheral surface of the hole 36c1. When the fitting of the output shaft 36b1 and the hole 36c1 becomes loose, when the self-alignment torque Tq increases to some extent due to the decrease in frictional force, the wheels are rotated even though the steering motor 36a is rotating. A phenomenon occurs in which the 12 cannot be steered.

As can be seen from the graph of FIG. 4A, assuming that the steering device 34 is normal and the vehicle traveling speed v is constant, the motor rotation amount θ is increased from the state of 0, which is the reference rotation position. By operating the steering motor 36a, the steering amount of the wheels 12 is increased from the reference position of 0, and then the motor rotation amount θ is decreased to 0 from the state where the steering amount is increased. By operating the steering motor 36a in this way, it is possible to return the steering amount to zero.

On the other hand, as can be seen from the graph of FIG. 4B, when the steering device 34 has a failure that causes the unsteering phenomenon, for example, the motor rotation amount θ is the phenomenon occurrence operation amount. From the time when the motor rotation amount θ _S is reached, the steering amount is maintained at a constant amount even if the motor rotation amount θ is continuously increased. When the motor rotation amount θ is reduced to 0 from the state where the steering motor 36a is operated to some extent beyond the motor rotation amount θ _{S, the wheels 12 are steered in the opposite direction beyond the reference position.} Will end up. The occurrence of the unsteerable phenomenon causes such a problem.

Further, if the state in which the steering failure phenomenon continues for a long time, the sliding between the hole 36c1 of the actuator arm 36c and the output shaft 36b1 of the speed reducer 36b is maintained, and the slack between them is maintained. Finally, the wheel 12 can hardly be steered. Therefore, once the unsteerable phenomenon occurs, it is desirable not to cause the unsteerable phenomenon thereafter.

Therefore, the steering device 34 is designed to detect the unsteering phenomenon. More specifically, as described above, in the process of increasing the steering amount of the wheel 12, a current i having a magnitude corresponding to the self-alignment torque Tq is supplied to the steering motor 36a. Therefore, when the steering impossibility phenomenon occurs, the supply current i to the steering motor 36a does not increase even if the motor rotation amount θ increases. That is, in this steering device 34, the steering impossible phenomenon occurs when the supply current i to the steering motor 36a does not increase even though the motor rotation amount θ increases. Recognize that it has occurred. In other words, the steering impossibility phenomenon is detected based on the operating amount of the steering motor 36a and the state of change in the supply current i to the steering motor 36a.

Further, in the steering apparatus 34, the motor rotation amount of time the supply current i is no longer increased theta is detected as a phenomenon generating motor rotation amount theta _S described above, beyond the phenomenon generating motor rotation amount theta _S steered Even if the motor 36a is rotated, the motor rotation amount θ is set to the phenomenon occurrence motor rotation amount θ _S. By performing such a measure, when the wheel 12 is returned to the reference position from the state where the steering impossible phenomenon occurs, the steering motor 36a is simply operated until the motor rotation amount θ becomes 0. It will be done.

Further, in the steering device 34, once the unsteering phenomenon is detected, the subsequent steering of the wheels 12 is restricted. More specifically, in this steering device 34, the self-alignment torque Tq at the present time is estimated based on the motor rotation amount θ and the vehicle traveling speed v, and when the steering impossible phenomenon occurs, at that time. The self-alignment torque Tq minus the margin torque Tq _M is certified as the limit torque Tq _0. After that, steering of the wheel 12 in a state where the self-alignment torque Tq _{exceeds the limit torque Tq 0 is prohibited.} Specifically, when the self-alignment torque Tq _{exceeds the limit torque Tq 0} , the target motor rotation amount θ ^* is set to the current motor rotation amount θ. Incidentally, the margin torque Tq _M is set so that the limit torque Tq ₀ has a certain margin.

When no steering restriction is applied to any of the four wheels 12, the vehicle is appropriately steered according to the operation amount δ of the steering wheel 54. For example, FIG. 5A shows a state in which each wheel 12 is steered when the vehicle turns with an operation amount δ facing to the right. By the way, the rear wheels 12 are steered in the opposite direction to the front wheels 12. On the other hand, when the steering is restricted to any of the four wheels 12, the turning amount of the vehicle is reduced. For example, FIG. 5B shows a case where the right front wheel 10 is restricted from steering, but the vehicle turns to the right, but the amount of steering of the right front wheel 10 is not sufficient. , It is steering of a vehicle with a slight understeer.

In this steering system, when steering restriction is applied to any one of the front, rear, left, and right wheels 12, the steering amount of one or more of the other wheels 12 is increased in order to alleviate the shortage of the turning amount. It is configured as follows. That is, when the steering impossibility phenomenon occurs, the support process for steering the vehicle is executed. ^{More specifically, the target motor rotation amount θ *} of the steering motor 36a of the steering device 34 provided for each of one or more of the other wheels 12 is changed by a certain change dθ ^* (hereinafter, “support motor rotation”). It is designed to change only the quantity dθ ^{* ”).} For example, as shown in FIG. 5C, when steering is restricted to the right front wheel 12 when turning right, the left front wheel 12, the right rear wheel 12, and the left rear wheel 12 are turned respectively. The amount of rudder is increased. By the way, how much the steering amount of the other wheels 12 is increased or decreased based on the turning direction of the vehicle and the wheels 12 subject to the steering restriction, that is, the support motor for the other wheels 12. The rotation amount dθ ^* may be arbitrarily set based on the concept of the vehicle or the like.

iii) Control flow The steering control of the wheels 12 in the steering device 34, specifically, the steering control including the detection of the steering impossible phenomenon and the processing for coping with the steering impossible phenomenon is shown in FIG. The wheel steering program shown in the flowchart is repeatedly executed by the computer of the steering ECU 50 at a short time pitch (for example, several meters to several tens of msec). The flow of processing according to the program will be briefly described below. Regarding the direction of steering of the wheel 12, there is no difference in processing on either the left or right side, and it can be considered that the magnitude of the self-alignment Tq is the same on both the left and right sides. The direction of steering of the wheels 12 is not limited. Further, it is assumed that the non-steering phenomenon does not occur for two or more wheels, and the following description will be given.

In the process according to the wheel steering program, first, in step 1 (hereinafter, abbreviated as “S1”; the same applies to other steps), the operation amount δ of the steering wheel 54 is changed to another based on the detection of the steering sensor 56. The vehicle traveling speed v is acquired from the system (for example, a braking system, etc.), and the current motor rotation amount θ is acquired based on the detection of the motor rotation angle sensor of the steering motor 36a.

Next, in S2, it is determined whether or not the operation amount δ of the steering wheel 54 is 0, that is, whether or not the steering wheel 54 is located at a rotational position where the vehicle is positioned to move straight. When the operation amount δ is 0, it is considered that the steering motor 36a is currently positioned at the reference rotation position in S3, and the calibration of the motor rotation amount θ, that is, the actual motor rotation amount θ is performed. The process of setting to 0 is performed, and one execution of the program is completed. On the other hand, when it is determined in S2 that the operation amount δ is not 0, that is, when it is determined that the steering operation for turning the vehicle is being performed, in S4, the control target of the steering motor 36a is set. The target motor rotation amount θ ^* is determined based on the operation amount δ, and in S5, the self-alignment torque Tq received by the wheel 12 is estimated based on the actual motor rotation amount θ and the vehicle traveling speed v. ..

In the following S6, the value of the flag DF is determined. The flag DF is a flag whose value is set to "1" when the above-mentioned non-steering phenomenon occurs on the wheel 12, and is a value when the above-mentioned non-steering phenomenon has not occurred even once. Is a flag whose initial value is "0". If the value of the flag DF is "1", the steering restriction processing of S7 is executed, and if the value of the flag DF remains "0", the steering restriction processing of S7 is skipped. Will be done. The steering restriction process of S7 will be described later.

After the steering limiting process is executed or after the steering limiting process is skipped, in S8, a steering impossibility phenomenon appears on the wheels 12 other than the wheel 12, and the steering device of the wheel 12 From 34, it is determined whether or not a support request has been made to the steering device 34 of the wheel 12. That is, it is determined whether or not the steering ECU 50 of the steering device 34 has obtained the above-mentioned steering restriction on the wheels 12 other than the wheel 12. When the support request is received, the steering support process of S9 is executed, and when the support request is not received, the steering support process of S9 is skipped. The steering support process of S9 will be described later.

After the steering assist process is executed or the steering assist process is skipped, the target motor rotation amount θ ^* already determined in S10, or the target motor changed by the steering restriction process described later. ^{The motor rotation amount deviation Δθ (= θ *} −θ) is determined based on the target motor rotation amount θ ^* corrected by the rotation amount θ ^* or the steering support process and the acquired actual motor rotation amount θ. , S11, the current i supplied to the steering motor 36a is determined based on the determined motor rotation amount deviation Δθ. Then, in S12, the current meaning i is supplied to the steering motor 36a.

In the following S13, when the value of the flag DF described above is determined again and the value of the flag DF is determined to be "0", the steering impossible phenomenon detection process of S14 is executed, and 1 of the program concerned. The execution of the times is completed. When the value of the flag DF is "1", since the unsteering phenomenon has already been detected, the processing of S14 is skipped and one execution of the program is terminated.

The non-steering phenomenon detection process of S14 is performed by executing the non-steering phenomenon detection subroutine shown in the flowchart in FIG. 7A. In accordance processing the subroutine, first, in S21, the target motor rotation amount is determined theta ^* is determined whether the increase process, if the target motor rotation amount theta ^* is increasing process, step S22 , It is determined whether or not the current i supplied to the steering motor 36a is increasing. If the target motor rotation amount θ ^* is not in the increasing process, or if the target motor rotation amount θ ^* is in the increasing process and the supply current i is increasing, the reset process of the time counter t, which will be described later, is performed in S23. It is executed and the execution of the subroutine is terminated.

If the supply current i does not increase even though the target motor rotation amount θ ^* is in the process of increasing, it is presumed that a steering failure phenomenon may occur. In S24, the steering failure phenomenon occurs. It is determined whether or not the value of the time counter t for measuring the passage of time since the possibility of occurrence of the above is estimated is "0". When the value of the time counter t is "0", in S25, the phenomenon occurrence motor rotation amount θ _S , which is the motor rotation amount θ at which the steering impossible phenomenon occurs, is set to the actual motor rotation amount θ at the present time. If the value of the time counter t is not "0", the processing of S25 is skipped, and in S26, the value of the time counter t counts up by the count-up value Δt corresponding to the execution pitch of the program. Will be done.

In the next S27, it is determined whether or not the value of the time counter t exceeds the set threshold time t _0. When it is determined that the value of the time counter t _{exceeds the threshold time t 0} , the value of the flag DF is set to "1" in S28 in order to confirm that the steering inability phenomenon has occurred. .. Then, in S29, the actual motor rotation amount θ at the present time is set to the phenomenon occurrence motor rotation amount θ _S , and the limit torque Tq ₀ is obtained by subtracting the _{margin torque Tq M} from the self-alignment torque Tq estimated at the present time. Set to a value. Further, in S30, the instrument panel of the vehicle is displayed with a warning sound indicating that the steering device 34 is unable to steer, and the driver is notified of the information on the inability to steer. Rudder. If it is determined in S27 that the value of the time counter t _{does not exceed the threshold time t 0} , the processes of S28 to S30 are skipped.

When it is determined in S6 that the value of the flag DF is "1", the steering restriction processing performed in S7 is performed by executing the steering restriction subroutine shown in the flowchart in FIG. 7B. In the process according to the steering restriction subroutine, in S31, it is determined whether or not the _{self-alignment torque Tq estimated at the present time exceeds the limit torque Tq 0.} When it is determined that the self-alignment torque Tq _{exceeds the limit torque Tq 0} , the target motor rotation amount θ ^* is set to the current actual motor rotation amount θ in S32, and the motor rotation amount θ increases. Steering of the wheels 12 is prohibited. Then, in S33, the steering device 34 of the other wheel 12 is requested to support the vehicle steering via the CAN 62. If it is determined in S31 that the self-alignment torque Tq _{does not exceed the limit torque Tq 0} , the processes of S32 and S33 are skipped.

The steering support process performed in S9 when it is determined in S8 that a support request has been made to the steering device 34 of the wheel 12 from the steering device 34 of the other wheel 12 is shown in FIG. 7 (c). This is done by executing a steering support subroutine that shows a flowchart. In the process according to this subroutine, in S41, which wheel 12 is set as the target wheel 12 by the steering device 34 requesting support, that is, the support request wheel is specified. ^{In the next S42, the above-mentioned support motor rotation amount dθ *} is determined in order to compensate for the shortage of the turning amount of the vehicle based on the relationship between the specified support request wheel and the target wheel 12 of the steering device 34. , S43, the target motor rotation amount θ ^* is corrected based on the determined support motor rotation amount dθ ^*.

10: Vehicle wheel arrangement module 12: Wheel 14: Wheel drive unit 14a: Housing [Steering knuckle] 14b: Knuckle arm 34: Steering device 36: Steering actuator 36a: Steering motor [Electric motor] [Drive source] 36b: Reducer 36c: Actuator arm 38: Tie rod 40: Ball joint for connecting rod base end 42: Ball joint for connecting rod tip 50: Steering electronic control unit (steering ECU) [Controller] 52: Operating device 54 : Steering wheel [Steering operation member] 56: Steering sensor 58: Reaction force applying device 60: Operation electronic control unit (operation ECU) 62: CAN

Claims (1)

A steering device that is deployed in a vehicle, each of which has a plurality of wheels that can be steered, and that steers one of the plurality of wheels independently.
It is equipped with an actuator having an electric motor as a drive source and a controller that controls the supply current to the electric motor to steer the wheels according to the operating amount of the electric motor.
The controller detects a non-steering phenomenon in which the wheels cannot be steered even though the electric motor is operating, based on the amount of operation of the electric motor and the state of change in the supply current to the electric motor. A steering device configured to do so.

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