JP2012006487A - Steer-by-wire system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To instantly enable ordinary steering after restarting a system, and to control a consumption electric current, by putting a steering lock mechanism in a lock state when stopping a steer-by-wire system.SOLUTION: The steer-by-wire system includes a reaction generating motor for generating reaction corresponding to road surface reaction in a steering wheel, by mechanically separating the steering wheel and a steered wheel. The steer-by-wire system includes the steering lock mechanism for making turning operation of the steering wheel impossible in the lock state and allowing the turning operation of the steering wheel in a lock release state, and rotates a steering shaft until the steering lock mechanism becomes the lock state by driving the reaction generating motor when stopping the steer-by-wire system.

Description

  The present invention relates to a steer-by-wire system, and more particularly to a steer-by-wire system that keeps the steering lock mechanism locked when the steer-by-wire system is stopped, and allows normal steering immediately after system restart, while suppressing current consumption. is there.

Some vehicles are equipped with a steer-by-wire steering system, that is, a steer-by-wire system.
This steer-by-wire system operates a steering wheel in a desired steering state in consideration of a steering wheel (also referred to as a “steering handle” or “handle”) that is artificially operated by a driver and an operation state of the steering wheel. A steering mechanism, a plurality of actuators that are used for steering control in the operation of the steering wheel or the operation of the steering mechanism, and that consumes electric power, and a plurality of control devices that supply power to these actuators to control the operation state.

JP 2006-62627 A JP 2006-306141 A JP 2007-153109 A

By the way, in the conventional steer-by-wire system, when the steering wheel is turned off while the power is turned off, the above-mentioned Patent Document 1 starts the system and drives the steering wheel reaction force generation motor to turn the steering wheel to the middle point. A technique for returning is disclosed.
Further, in Patent Document 3 described above, when there is a difference between the steering wheel angle and the tire cutting angle while the system is stopped, the steering wheel angle is set to be positive and control is performed so that the tire cutting angle matches this, thereby achieving harmony. There is disclosed a policy or a policy for making the tire turning angle positive and controlling the steering wheel turning angle so as to match the tire turning angle.
In the prior art disclosed in Patent Document 1 described above, the steering wheel and tires (also referred to as “steering wheels”) are automatically turned off after the system is restarted. There is an inconvenience that the driver waits until this time, or an unusual steering feeling occurs.
For this reason, when the steer-by-wire system stops, a tire turning angle corresponding to the turning angle of the steering wheel is guaranteed, and an improvement that can eliminate the waiting time and uncomfortable feeling at the time of restart has been desired.
Further, the above-described Patent Document 3 monitors the state of the steering wheel while the steer-by-wire system is stopped, and controls to start the system and return the steering wheel to the neutral position when rotation of the steering wheel is detected. Therefore, there is an inconvenience that current consumption increases.
For reference, the above-described Patent Document 2 discloses a technique for detecting a lock groove or a distance to a detection groove using a lock groove position detection sensor.
In Patent Document 2, it is described that the locked state and the unlocked state of the steering lock mechanism are determined based on the detected distance.
The lock groove position detection sensor detects a distance using laser light or ultrasonic waves. The steering lock detection sensor of the present invention can be considered to be similar to the lock groove position detection sensor of Patent Document 2 as an example.

  It is an object of the present invention to lock the steering lock mechanism when stopping the steer-by-wire system, to enable normal steering immediately after the system is restarted, and to suppress current consumption.

  Accordingly, in order to eliminate the above-described disadvantage, the present invention is a steer-by-wire equipped with a reaction force generation motor that mechanically separates the steering wheel and the steering wheel and generates a reaction force corresponding to the road surface reaction force on the steering wheel. The system includes a steering lock mechanism that disables the turning operation of the steering wheel in the locked state and allows the turning operation of the steering wheel in the unlocked state, and when the steer-by-wire system is stopped, The reaction force generating motor is driven to rotate the steering shaft until the steering lock mechanism is locked.

As a result, the steer-by-wire system can be stopped after the steering angle and the tire angle are reliably matched. Therefore, normal steering can be performed immediately after the system is restarted.
In the prior art, the state of the steering wheel is monitored while the steer-by-wire system is stopped, and if the rotation of the steering wheel is detected, the steer-by-wire system is activated to control the steering wheel to return to the neutral position. There is a problem that becomes larger.
In the present invention, since the steering lock state is set when the steer-by-wire system is stopped, the steering wheel does not rotate thereafter. Therefore, current consumption can be suppressed.
Further, in the prior art, when the ignition switch is turned on, normal steering cannot be performed until the steering wheel is returned to the neutral position.
In the present invention, since the steering lock state is set, the steering wheel does not rotate. Therefore, normal steering can be performed immediately after the system is restarted.

FIG. 1 is a flowchart for a stop logic of a steer-by-wire system showing an embodiment of the present invention. (Example) FIG. 2 is a flowchart for activation logic of the steer-by-wire system. (Example) FIG. 3 is a schematic configuration diagram of a steer-by-wire system. (Example)

  Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention.
In FIG. 3, 1 is a steer-by-wire system of a vehicle (not shown).
This steer-by-wire system 1 employs a so-called steer-by-wire system, and takes the steering wheel 2 that is artificially operated and the steered wheels 3 and 4 into a desired steering state in consideration of the operation state of the steering wheel 2. A steering mechanism 5 that operates, and a plurality of actuators that are used for steering control in the operation of the steering wheel 2 or the operation of the steering mechanism 5, such as a steering motor 6 and first and second steering motors 7, 8, A plurality of first to third control devices 9 to 11 for supplying power to the motors 6 to 8 to control the operation state, a generator (not shown) for generating electric power, storing the generated electric power and And a plurality of power supplies (not shown) that can be supplied to other devices.

The steering wheel 2 is attached to one end of a steering shaft 13 that is rotatably supported by a steering column 12.
The steering column 12 is provided with the steering motor 6 as an actuator for assisting (assisting) the reaction force or the rotation with respect to the rotation when the driver operates the steering wheel 2.
The driving force of the steering motor 6 is transmitted to the steering shaft 13 via a steering motor gear (not shown) built in the steering column 12.
The steering column 12 is provided with steering wheel rotation detecting means 14 for detecting the rotation angle of the steering wheel 2.
The steering wheel rotation detection means 14 includes first and second rotation angle sensors 14 a and 14 b that detect the rotation angle of the steering shaft 13 as the rotation angle of the steering wheel 2.
Between the first and second rotation angle sensors 14a and 14b, a torque sensor 15 that detects the rotation torque of the steering shaft 13 as the rotation torque of the steering wheel 2 is provided.

The steering mechanism 5 includes a pinion shaft 16 that is rotated in consideration of the operation state of the steering wheel 2, and the rotational motion of the pinion shaft 16 is converted into a linear motion by a steering gear (not shown). The left and right tie rods 18 are provided with a steering gear box 17 that transmits to a rack shaft (not shown), and transmits linear motion to the left and right steering wheels 3 and 4 at both ends of the rack shaft (not shown). 19 is provided.
The steering gear box 17 is provided with a steering motor gear box 20 that supports the pinion shaft 16.
The steering motor gear box 20 is rotatably supported with one end of the pinion shaft 16 exposed to the outside, and the other end of the pinion shaft 16 is connected to the rack shaft by a steering gear in the steering gear box 17.
At this time, the steer-by-wire system 1 moves the steering wheels 3 and 4 based on the rotation angle of the steering wheel 2 detected by the first and second rotation angle sensors 14a and 14b of the steering wheel rotation detection means 14. The first and second steering motors 7 and 8 for steering are provided.
That is, the steering motor gear box 20 is provided with the first and second steering motors 7 and 8 as a plurality of actuators that rotate the pinion shaft 16 to operate the steering wheels 3 and 4 in a desired steering state. ing.
The driving forces of the first and second steering motors 7 and 8 are transmitted to the pinion shaft 16 by a steering motor gear built in the steering motor gear box 20.

In the first to third control devices 9 to 11, the first control device 9 includes a steering motor control device that supplies power to the steering motor 6 to control the operation state, and the second control device 10 includes The first steering motor 7 includes a first steering motor control device that controls the operation state by supplying power to the first steering motor 7, and the third control device 11 supplies power to the second steering motor 8 to control the operation state. Control device.
At this time, the steering motor 6 is connected to the first control device 9 including a steering motor control device.
The first steering motor 7 is connected to the second control device 10 including the first steering motor control device.
The second steering motor 8 is connected to the third control device 11 including the second steering motor control device.
The first control device 9 including the steering motor control device and the second and third control devices 10 and 11 including the first and second steering motor control devices are control means of the steer-by-wire system 1. 21 is constituted.
A display alarm device 22 and vehicle information detection means, for example, vehicle speed detection means 23 are connected to the control means 21.
At this time, the display warning device 22 performs notification by displaying a buzzer or the like such as a vehicle alarm.
The vehicle information detection means includes a vehicle speed detection means for detecting the vehicle speed, an engine speed detection means for detecting the engine speed, a switch state detection means for detecting the ignition switch state, and a shift for detecting the shift position of the transmission. This embodiment comprises position detecting means, and in this embodiment, the vehicle speed detecting means 23 will be described.

In the steer-by-wire system 1, the steering wheel 2 and the steering wheels 3 and 4 are mechanically separated, and the steering wheel 2 operates as a reaction force generation motor that generates a reaction force corresponding to a road surface reaction force. A motor 6 is provided.
In addition, the steer-by-wire system 1 drives the first and second steering motors 7 and 8 according to the rotation angle of the steering wheel 2 detected by the first and second rotation angle sensors 14a and 14b, thereby the steering wheel. Control to turn 3, 4 left and right.
At this time, the road surface reaction force to the steering wheel 2 is applied by the first control device 9 controlling the steering motor 6.

The steering wheel 2 is connected to the first rotation angle sensor 14a of the steering wheel rotation detecting means 14, the steering column 12, the torque sensor 15, and the steering wheel 2 from the steering wheel 2 side via the steering shaft 13. A second rotation angle sensor 14b of the steering wheel rotation detection means 14 is sequentially provided, and the reaction force generation mechanism 24 and the rotation stopper mechanism 25 are provided in the second rotation angle sensor 14b portion.
At this time, the rotation stopper mechanism 25 is a mechanism that limits the number of rotations of the steering wheel 2.

  For reference, the reaction force generation mechanism 24 applies a reaction force to the steering wheel 2 in the same manner as the steering motor 6. The reaction force generation mechanism 24 is a failure of the steering motor 6. Since it is sometimes operated for emergency use, an energizing force such as a spring is assumed when a reaction force is applied to the steering wheel 2. In the steering motor 6 of the present invention, when a certain condition is satisfied, Since the reaction force is increased, it cannot be realized even if a reaction force generation mechanism is used.

Furthermore, the steering motor gear box 20 is provided with pinion shaft rotation detecting means 26 for detecting the rotation angle of the pinion shaft 16.
As shown in FIG. 3, the pinion shaft rotation detection means 26 includes two rotation angle sensors disposed between the pinion shaft 16 and the steering gear box 17, that is, third and fourth rotation angle sensors 14c, 14d.

The steer-by-wire system 1 includes a steering lock mechanism 27 that disables the turning operation of the steering wheel 2 in the locked state and allows the turning operation of the steering wheel 2 in the unlocked state. When the steer-by-wire system 1 is stopped, the steering motor 6 that is the reaction force generation motor is driven to rotate the steering shaft 13 until the steering lock mechanism 27 is locked.
More specifically, the steer-by-wire system 1 includes the first and second steering motors 7 and 7 according to the rotation angle detected by the pinion shaft rotation detection unit 26 including the third and fourth rotation angle sensors 14c and 14d. 8 is driven to control the steering wheels 3 and 4 to turn left and right.
At this time, the road surface reaction force to the steering wheel 2 is applied when the control means 21 drives and controls the steering motor 6 which is the reaction force generation motor.
The steering shaft 13 is fixed so as not to rotate by operating the steering lock mechanism 27.
At this time, the steering lock mechanism 27 is provided with a steering lock detection sensor 28 for detecting whether or not the steering lock is applied, as shown in FIG.
As a result, the steer-by-wire system 1 can be stopped after ensuring that the steering wheel angle and the tire cutting angle are consistent. Therefore, normal steering can be performed immediately after the system is restarted.
In the prior art, the state of the steering wheel 2 is monitored while the steer-by-wire system 1 is stopped, and when the rotation of the steering wheel is detected, the steer-by-wire system 1 is activated to control the steering wheel 2 to return to the neutral position. Therefore, there is a problem that current consumption increases.
In the present invention, since the steering lock state is set when the steer-by-wire system 1 is stopped, the steering wheel 2 does not rotate thereafter. Therefore, current consumption can be suppressed.
Further, in the prior art, when the ignition switch is turned on, normal steering cannot be performed until the steering wheel 2 is returned to the neutral position.
In the present invention, since the steering lock state is set, the steering wheel 2 does not rotate. Therefore, normal steering can be performed immediately after the system is restarted.

The steer-by-wire system 1 is used as a system stop condition.
(1) Turn off the ignition switch (IG OFF),
And,
(2) Vehicle speed = 0 km / h,
And,
(3) The steering wheel 2 is in a locked state.
In addition, the steer-by-wire system 1 is a system start condition,
(1) Turn on the ignition switch (IG ON),
Or
(2) The steering wheel 2 is in an unlocked state.
In addition, when the steering wheel 2 is unlocked, the steer-by-wire system 1 is restarted. Then, the steering wheel 2 is controlled again to be in a locked state. Therefore, the steering angle and the tire cutting angle can be reliably matched.
Furthermore, the steer-by-wire system 1 is
(1) Turn off the ignition switch (IG OFF),
And,
(2) Vehicle speed = 0 km / h,
And,
(3) When the steering wheel 2 is in the unlocked state, the steering motor 6 that is the reaction force generating motor is driven so that the system can be stopped, and the locking position of the steering lock mechanism 27 is about 10 deg / s. The steering wheel 2 is rotated at a low speed. At this time, the torque on the steering shaft 13 generated by the steering motor 6 is measured by the torque sensor 15 and is 0.5 Nm or less. If the steering wheel 2 is suddenly rotated, the steering wheel 2 may hit the driver's hand when the driver is touching the steering wheel 2. Therefore, the steering wheel 2 is rotated at a low speed and with a low torque.
At the same time, the steered wheels 3 and 4 are controlled so that the steered wheels 3 and 4 also have a tire turning angle corresponding to the steering wheel angle.
Further, the steering wheel 2 is turned to the left / right when it is turned to the right / left so that the final steering angle becomes small.
Then, the steering shaft 13 is rotated to the steering lock position, and when the state where the steering lock is detected by the steering lock detection sensor 28, the steer-by-wire system 1 is stopped.

  Next, the operation will be described along the flowchart for the stop logic of the steer-by-wire system 1 in FIG.

When the stop logic program of the steer-by-wire system 1 starts (101), the process proceeds to determination (102) of whether or not the ignition switch is in an OFF state.
If the determination (102) is YES in the determination (102) as to whether or not the ignition switch is in the OFF state, the vehicle speed detected by the vehicle speed detection means 23 is
Vehicle speed = 0km / h
When the determination (102) is NO, the process proceeds to a stop logic program end (110) of the steer-by-wire system 1 described later.
Also,
Vehicle speed = 0km / h
If the determination (103) is YES in the determination (103), the process proceeds to the control start handle angle θ acquisition process (104). If the determination (103) is NO, The process proceeds to the end (110) of the stop logic program of the steer-by-wire system 1.
After the control start handle angle θ acquisition process (104), the process proceeds to determination (105) as to whether or not the steering wheel 2 is locked.
In the determination (105) of whether or not the steering wheel 2 is in the locked state, if the determination (105) is YES, the process proceeds to a process (106) for stopping the steer-by-wire system 1, and thereafter Then, the process proceeds to the stop logic program end (110) of the steer-by-wire system 1.
In the determination (105) of whether or not the steering wheel 2 is in the locked state, if the determination (105) is NO, it is determined whether or not the control start handle angle θ is turned to the right ( 107).
In the determination (107) of whether or not the control start steering wheel angle θ is turned to the right, if the determination (107) is YES, the steering wheel 2 that is the steering wheel is rotated counterclockwise at 10 deg / s. (At this time, the torque of the steering shaft 13 is measured by the torque sensor 15 and regulated to 0.5 Nm or less.) After the process (108), the steering wheel 2 described above is in a locked state. Return to the judgment (105).
Further, in the determination (107) of whether or not the control start steering wheel angle θ is turned to the right, if the determination (107) is NO, the steering wheel 2 that is the steering wheel is rotated to the right at 10 deg / s. (At this time, the torque of the steering shaft 13 is measured by the torque sensor 15 and regulated to 0.5 Nm or less.) After that, the processing shifts to (109), and then the steering wheel 2 is locked. Return to the determination (105) of whether or not there is.

  Moreover, it demonstrates along the flowchart for starting logic of the said steer-by-wire system 1 of FIG.

When the startup logic program of the steer-by-wire system 1 is started (201), the process proceeds to a determination (202) as to whether or not the ignition switch is on.
If the determination (202) is YES in the determination (202) as to whether or not this ignition switch is on, the process proceeds to the process (203) for starting the steer-by-wire system 1, and then The process proceeds to the end (205) of the activation logic program of the steer-by-wire system 1 described later.
If the determination (202) is NO in the determination (202) of whether or not the ignition switch is in the ON state, determination is made as to whether or not the steering wheel 2 is locked off, that is, in the unlocked state ( 204).
If the determination (204) is YES in the determination (204) of whether or not the steering wheel 2 is locked off, that is, the lock is released, the process proceeds to a process (203) for starting the steer-by-wire system 1. Thereafter, the process proceeds to the end (205) of the activation logic program of the steer-by-wire system 1, while if the determination (204) is NO, the end of the activation logic program (205) of the steer-by-wire system 1 is continued. ).

DESCRIPTION OF SYMBOLS 1 Steer-by-wire system 2 Steering wheel 3, 4 Steering wheel 5 Steering mechanism 6 Steering motor (reaction force generation motor)
7, 8 First and second steering motors 9-11 First to third control devices 12 Steering column 13 Steering shaft 14 Steering wheel rotation detecting means 15 Torque sensor 16 Pinion shaft 17 Steering gear box 18, 19 Left and right tie rods 20 Steering Motor gear box 21 Control means 22 Display alarm device 23 Vehicle speed detection means 24 Reaction force generation mechanism 25 Rotation stopper mechanism 26 Pinion shaft rotation detection means 27 Steering lock mechanism 28 Steering lock detection sensor

Claims (1)

  In a steer-by-wire system in which a steering wheel and a steering wheel are mechanically separated and a reaction force generation motor that generates a reaction force corresponding to a road surface reaction force is generated on the steering wheel, the steering wheel is rotated in a locked state. A steering lock mechanism that allows the steering wheel to rotate in an unlocked state, and when the steer-by-wire system is stopped, the reaction force generation motor is driven to A steer-by-wire system that rotates the steering shaft until it is locked.

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