JP2012071692A - Steer-by-wire system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an operation angle of a steering wheel and a steering angle of a steering wheel not adjusted during a vehicle running, and to adjust the operation angle of the steering wheel and the steering angle of the steering wheel under stopping.SOLUTION: A steer-by-wire system which includes: an operation angle detector which mechanically separates the steering wheel and the steering wheel, and detects the operation angle of the steering wheel; a steering angle detector which detects the steering angle of the steering wheel; and a controller which adjusts the operation angle and the steering angle when a gap arises between the operation angle detected by the operation angle detector and the steering angle detected by the steering angle detector, when starting the steer-by-wire system, includes a vehicle speed detector which detects vehicle speed. The controller adjusts the operation angle and the steering angle, when the vehicle speed detected by the vehicle speed detector becomes nearly zero, after starting the steer-by-wire system.

Description

  The present invention relates to a steer-by-wire system, and in particular, when the steering wheel operating angle and the steering wheel steering angle are matched, the steering wheel operating angle and the steering wheel steering angle are not matched during vehicle travel. The present invention relates to a steer-by-wire system that aligns an operation angle of a steering wheel and a steering angle of a steered wheel while the vehicle is stopped.

In a steer-by-wire system, when the system is stopped, the operation angle, which is the turning angle of the steering wheel (also referred to as “handle”), cannot be matched with the steering angle, which is the turning angle of the steering wheel (also referred to as “tire”). The following two methods are considered as methods for achieving alignment so that the vehicle can go straight.
(1) The steering wheel side is moved so as to match the current steering wheel operating angle.
(2) Move the steering wheel side so that it matches the steering angle of the current steering wheel.
Then, one or both of the above-mentioned two methods of the above method are carried out, and the driver is informed of the alignment using a display means or the like.
Further, in Patent Document 1 described later, there is disclosed a method for aligning the steering wheel and the steering wheel at the midpoint of the deviation between the steering wheel and the steering wheel.

JP 2007-153109 A

By the way, in the conventional steer-by-wire system, the method of matching the steering wheel side with the current steering wheel operating angle has the following disadvantages, so it is better not to implement it: .
(A) When the system is started during driving due to system failure or power interruption, if the steered wheels are arbitrarily cut from the final position, the driving direction of the vehicle unintended by the driver will change. End up.
(A) The current consumption is smaller when the steering wheel side is aligned than when the steering wheel side is aligned.
Therefore, when the vehicle is started while the vehicle is stopped, it is better to control the steering wheel side so as to match the steering angle on the steering wheel side.
Also, if the system is started in an inconsistent state while the vehicle is running, it is better not to use any logic.

  An object of the present invention is to match the steering wheel operation angle and the steering wheel steering angle while the vehicle is stopped without matching the steering wheel operation angle and the steering wheel steering angle.

  Accordingly, in order to eliminate the above-described disadvantages, the present invention mechanically separates the steering wheel and the steering wheel, detects the steering angle of the steering wheel, and detects the steering angle of the steering wheel. A steering angle detection means for operating the steering angle when the steer-by-wire system is activated and there is a deviation between the operation angle detected by the operation angle detection means and the steering angle detected by the steering angle detection means. In a steer-by-wire system comprising control means for matching the steering angle, vehicle speed detection means for detecting vehicle speed is provided, and the control means has a vehicle speed detected by the vehicle speed detection means of approximately 0 after the steer-by-wire system is activated. In this case, the operation angle and the steering angle are matched.

According to the present invention, since the operation angle of the steering wheel and the steering angle of the steered wheel are not matched while the vehicle is traveling, it is possible to avoid a change in the traveling direction of the vehicle that is not intended by the driver.
In addition, since the steering wheel operating angle and the steering wheel steering angle are matched when the vehicle is stopped, the steering wheel operating angle and the steering wheel steering angle can be matched without causing the driver to feel uneasy. .

FIG. 1 is a flowchart for controlling the steer-by-wire system. (Example) FIG. 2 is a schematic configuration diagram of the steer-by-wire system. (Example)

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

1 and 2 show an embodiment of the present invention.
In FIG. 2, 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 includes a steering wheel 2 that is artificially operated, and a steered wheel (“front wheel” or “tire”) that is mechanically separated from the steering wheel 2. 3), 4 and 4 are used for the steering mechanism 5 which operates in a desired steering state in consideration of the operation state of the steering wheel 2, and the power used for the steering control of the steering wheel 2 or the operation of the steering mechanism 5 is consumed. A plurality of actuators, for example, a steering motor 6 and first and second steering motors 7 and 8, first to third control devices 9 to 11 for supplying electric power to these motors 6 to 8 to control their operation states, and electric power Generators (not shown) that generate electricity and multiple power sources that can store the generated power and supply it to other devices And a not shown) and.

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 6 is provided with the steering motor 6 as an actuator that outputs a reaction force against the rotation when the driver operates the steering wheel 2 or a force that assists (assistes) the rotation.
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.
Further, the steering column 12 is provided with operation angle detection means 14 for detecting the operation angle of the steering wheel 2.
The operation angle detection unit 14 includes first and second operation angle detection units 14 a and 14 b that detect the rotation angle of the steering shaft 13 as the operation angle of the steering wheel 2.
Between these first and second operation angle detecting means 14a and 14b, a torque sensor 15 for detecting the rotational torque of the steering shaft 13 as the operation torque of the steering wheel 2 is provided.

As shown in FIG. 2, the steering mechanism 5 includes a pinion shaft 16 that is rotated in consideration of the operation state of the steering wheel 2, and a steering gear (not shown) that incorporates the rotational motion of the pinion shaft 16. A steering gear box 17 is provided for converting into linear motion and transmitting it to a rack shaft (not shown). At both ends of the rack shaft (not shown), linear motion is transmitted to the left and right steering wheels 3 and 4 for steering. Left and right tie rods 18 and 19 are 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 operation angle of the steering wheel 2 detected by the first and second operation angle detection means 14a and 14b of the operation angle 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 plurality of 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 includes the second and third control devices. The control devices 10 and 11 include first and second steering motor control devices that control the operation state by supplying power to the first and second steering motors 7 and 8.
At this time, the steering motor 6 is connected to the first control device 9 including a steering motor control device.
The first and second steering motors 7 and 8 are connected to the second and third control devices 10 and 11, respectively, which are the first and second steering motor control devices.
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.

The steering wheel 2 is connected to the steering wheel 22 via the steering shaft 13 from the steering wheel 22 side, the first operation angle detection means 14a of the operation angle detection means 14, the steering column 12, the torque sensor 15, and the operation. The second operation angle detection means 14b of the angle detection means 14 is sequentially provided, and the reaction force generation mechanism 24 and the rotation stopper mechanism 25 are provided in the second operation angle detection means 14b portion.
At this time, the rotation stopper mechanism 25 is a mechanism that limits the number of rotations of the steering wheel 2.

  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 used for emergency when the steering motor 6 fails. Since it operates, energizing force such as a spring is assumed when a reaction force is applied to the steering wheel 2.

Further, the steering motor gear box 20 is provided with pinion shaft rotation detection means for detecting the rotation angle of the pinion shaft 16, that is, steering angle detection means 26.
As shown in FIG. 2, the steering angle detection means 26 includes two rotation angle sensors disposed between the pinion shaft 16 and the steering gear box 17, that is, first and second steering angle detection means 26a, 26b.

In the steer-by-wire system 1, the steering wheel 2 and the steering wheels 3, 4 are mechanically separated, and the operation angle detection means 14 that detects the operation angle of the steering wheel 2 and the steering wheels 3, 4 The steering angle detector 26 detects the steering angle of the steering angle, and the controller 21 detects the operation angle detected by the operation angle detector 14 and the steering angle detector 26 when the steer-by-wire system is activated. When there is a deviation from the steering angle, the operation angle and the steering angle are matched.
Further, the steer-by-wire system 1 includes the vehicle speed detecting means 23 for detecting a vehicle speed (also simply referred to as “vehicle speed”), and the control means 21 is detected by the vehicle speed detecting means 23 after the steer-by-wire system is activated. When the vehicle speed is approximately zero, the operation angle and the steering angle are matched.
More specifically, since there is no mechanical connection between the steering column 12 and the steering gear box 17, the steering wheel 2 can be freely moved within the range where the steering lock is not applied while the steer-by-wire system 1 is stopped. Can be cut.
For this reason, it is possible that the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are shifted while the steer-by-wire system 1 is stopped.
In order to eliminate such problems, the control means 21 activates the steer-by-wire system 1 in a state where the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are not aligned. After that, the steering motor 6 is controlled by the first control device 9 so that the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are matched.
At this time, if the steering wheel 2 is suddenly rotated, the driver may feel uneasy. Therefore, the control means 21 controls the steering motor 6 with the first control device 9 to control the steering wheel. When the steering reaction force to 2 is generated, it is rotated at a low angular velocity, for example, 10 deg / s in the direction of alignment.
Therefore, since the operation angle of the steering wheel 2 and the steering angle of the steered wheels 3 and 4 are not matched while the vehicle is traveling, it is possible to avoid a change in the traveling direction of the vehicle that is not intended by the driver.
Further, since the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are matched while the vehicle is stopped, the operation angle of the steering wheel 2 and the steering wheels 3 and 4 are steered without feeling uneasy by the driver. The corners can be aligned.

The control means 21 detects the operation angle detected by the operation angle detection means 14 and the steering angle detection means 26 when the steer-by-wire system is activated and the vehicle speed detected by the vehicle speed detection means 23 is not substantially zero. The operation angle of the steering wheel 2 is corrected using the difference from the operation angle corresponding to the steering angle as a correction amount.
That is, the control means 21 turns off the steering wheel 2 when the steer-by-wire system 1 is started in a state where the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are not aligned. The amount of deviation between the angle (also referred to as “steering angle”) and the turning angle of steering wheels 3 and 4 (also referred to as “tire angle”) is stored as a correction amount θdiff of the steering angle of the steering wheel 2, and the vehicle During traveling, the turning angle of the steering wheels 3 and 4 is controlled by the turning angle of the steering wheel 2 with the correction amount θdiff corrected.
Then, when the vehicle is subsequently stopped, the turning angle of the steering wheel 2 is set to the steering wheel by using the control for matching the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 described above. Adjustment is made so that the cut angles of 3 and 4 can be matched.
When the vehicle starts to travel again during the alignment, the correction is continued using the latest correction amount θdiff.
Therefore, even if the steer-by-wire system 1 is restarted while the vehicle is running, the relationship between the steering angle of the steering wheels 3 and 4 with respect to the operation angle of the steering wheel 2 does not change, so the driver operates the steering wheel 2. In this case, the operational feeling of the steering wheel 2 can be kept unchanged from that before the steer-by-wire system 1 is restarted.

The steering motor 6 that applies a steering reaction force to the steering wheel 2 is provided, and the steering motor 6 is driven to rotate the steering shaft 13 so that the operation angle and the steering angle are matched.
In other words, the control means 21 drives the steering motor 6 to rotate the steering shaft 13 when the steering motor 6 is controlled by the first control device 9 to apply a steering reaction force to the steering wheel 2. Thus, the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are controlled to be matched.
As a result, the steering angle of the steering wheels 3 and 4 is not adjusted to the operation angle of the steering wheel 2, but the operation angle of the steering wheel 2 is adjusted to the steering angle of the steering wheels 3 and 4, thereby reducing power consumption. Can do.
Further, when the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are matched, the operation angle of the steering wheel 2 changes, so that the driver can recognize that the matching is in progress.

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

When the control program of the steer-by-wire system 1 starts (101), the angle difference between the operation angle detected by the operation angle detection means 14 and the operation angle corresponding to the steering angle detected by the steering angle detection means 26 Then, the process proceeds to the processing (102) for calculating the correction amount θdiff as follows.
Correction amount θdiff = steering wheel angle−pinion angle At this time, the “pinion angle” is a tire turning angle obtained by converting the turning angle of the steerable wheels 3 and 4 that is a tire turning angle into a steering wheel angle.
Then, after the processing (102), whether the correction amount θdiff exceeds 10 deg, that is, θdiff> 10 deg.
It shifts to judgment (103) of whether it is.
If the determination (103) is NO in this determination (103), the process proceeds to the end (112) of the control program of the steer-by-wire system 1.
If the determination (103) is YES, the process proceeds to the process (104) for setting the correction necessary flag for the correction amount θdiff to “F = 1”.
After the processing (104) for setting the correction necessary flag of the correction amount θdiff to “F = 1”, whether “F = 1”, that is, the operation angle of the steering wheel 2 and the steering wheels 3, 4 The process proceeds to judgment (105) on whether or not matching with the steering angle is necessary.
If the determination (105) is NO in this determination (105), the process proceeds to the end (112) of the control program of the steer-by-wire system 1.
If the determination (105) is YES, the process proceeds to determination (106) as to whether or not the vehicle speed is “0”.
In this determination (106), when the determination (106) is NO,
Steering control steering wheel angle = steering wheel angle-θdiff
The process (107) is performed, and after this process (107), whether "F = 1" described above, that is, the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3, 4 The process returns to the determination (105) of whether or not matching is necessary.
At this time, it is assumed that the “steering control steering wheel angle” controls the turning angle of the steered wheels 3 and 4 that are tire turning angles so as to match the steering wheel angle.
Further, if the determination (106) as to whether or not the vehicle speed is “0” is YES, the steering motor 6 is controlled by the first control device 9 of the control means 21 to counter this steering motor 6. The process proceeds to a process (108) of generating a force and rotating the steering wheel 2 at a low angular velocity, for example, 10 deg / s in a direction in which the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are aligned.
After this processing (108), the processing shifts to processing (109) for calculating the correction amount θdiff, which is an angle difference, by the following equation.
Correction amount θdiff = handle angle−pinion angle After the process (109) for calculating the correction amount θdiff, the process proceeds to determination (110) as to whether or not the correction amount θdiff is “0”.
In the determination (110) of whether or not the correction amount θdiff is “0”, if the determination (110) is NO, “F = 1”, that is, the operation angle of the steering wheel 2 and The process returns to the determination (105) as to whether or not it is necessary to match the steering angle of the steerable wheels 3 and 4.
If the determination (110) is YES, the correction required flag of the correction amount θdiff is set to “F = 0”, that is, the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4 are matched. Shift to the processing (111) for completing the control, and then, is “F = 1”, that is, is it necessary to match the operation angle of the steering wheel 2 and the steering angle of the steering wheels 3 and 4? It returns to judgment (105) of no.

1 Steer-by-wire system 2 Steering wheel 3, 4 Steering wheel (also referred to as “front wheel” or “tire”)
DESCRIPTION OF SYMBOLS 5 Steering mechanism 6 Steering motor 7, 8 1st, 2nd steering motor 9-11 1st-3rd control apparatus 12 Steering column 13 Steering shaft 14 Operating angle detection means 14a, 14b 1st, 2nd operating angle detection means 15 Torque sensor 16 Pinion shaft 17 Steering gear box 18, 19 Tie rod 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 Steering angle detection means 26a, 26b First and second 2 Steering angle detection means

Claims (3)

  When the steer-by-wire system is activated, the steering wheel and the steered wheel are mechanically separated from each other, and an operation angle detection unit that detects an operation angle of the steering wheel and a steering angle detection unit that detects a steering angle of the steering wheel are provided. In a steer-by-wire system comprising control means for aligning the operation angle and the steering angle when there is a deviation between the operation angle detected by the operation angle detection means and the steering angle detected by the steering angle detection means Vehicle speed detecting means for detecting the vehicle speed, and the control means, when the steer-by-wire system is activated, when the vehicle speed detected by the vehicle speed detecting means falls below a preset value, the operation angle and the steering angle A steer-by-wire system characterized by   The control means detects the operation angle detected by the operation angle detection means and the steering angle detection means when the steer-by-wire system is activated and the vehicle speed detected by the vehicle speed detection means is greater than a preset value. The steer-by-wire system according to claim 1, wherein the operation angle of the steering wheel is corrected using a difference from an operation angle corresponding to the steering angle as a correction amount.   3. A steering motor for applying a steering reaction force to the steering wheel is provided, and the steering angle is adjusted by driving the steering motor to rotate the steering shaft. Steer-by-wire system as described in.

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