JP4283550B2 - Steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering device for a vehicle, and more particularly to a steer-by-wire steering device in which a driving operation device and a steering device mechanism are mechanically separated.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an automatic driving system for a vehicle that performs automatic driving by controlling the speed and steering angle of the vehicle based on information from various sensors has been proposed. Examples of the automatic driving system include an automatic driving system such as a lane keeping support for driving a vehicle along a guideway on a road, and an automatic tracking system for causing a preceding vehicle to follow another vehicle (see, for example, Patent Document 1). ).
On the other hand, a steering device using a steering wheel is known as a driving operation device that steers a steered wheel of a vehicle. A general steering device converts a rotating motion of a steering wheel into a linear motion of a rack shaft in a steering gear box, and drives a link mechanism connected to the rack shaft to steer the steered wheels. However, recently, in a steering device, a driving operation device and a steering device mechanism are mechanically disconnected, and a steering motor provided in the steering device mechanism is electrically controlled from the driving operation device, so-called steer-by-wire (Steer). (By Wire, hereinafter referred to as SBW).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-10078 (see paragraphs [0053] to [0064], [FIG. 4], [FIG. 5], etc.)
[0004]
[Problems to be solved by the invention]
However, in the conventional SBW type steering device, the driving operation device and the steering device mechanism operate one-on-one in a steady state. For this reason, when a conventional SBW-type steering device is mounted on a vehicle equipped with an automatic driving system, the steering wheel operates regardless of the driver's intention, which causes the driver to feel uncomfortable. is there.
[0005]
Therefore, in view of the above problems, the main object of the present invention is to provide a steering operation method during automatic driving that does not give the driver an uncomfortable feeling in the SBW steering device.
[0006]
[Means for Solving the Problems]
Of the present invention that solves the above problems, the invention according to claim 1 is: A steer-by-wire steering device in which a vehicle driving operation device and a steering device mechanism are mechanically separated, and outputs a target turning angle. When mounted on a vehicle equipped with an automatic driving system and the automatic driving system is operating, While turning the steered wheels of the vehicle by controlling the steering device mechanism based on the target turning angle, A steer-by-wire steering device comprising means for changing a rotation ratio between a steering angle in a driving operation device and a turning angle in a steering device mechanism. In an embodiment described later, the automatic driving system will be described as an “automatic tracking system”. In this configuration, the automatic tracking system outputs a signal indicating that the automatic tracking system is operating to a control device interposed between the driving operation device and the steering device mechanism. When the control device inputs the signal, the rotation ratio between the steering angle and the turning angle can be changed by using a predetermined ratio when calculating based on the steering angle and the turning angle. And
[0007]
According to a second aspect of the present invention, when the automatic driving system is operating, when at least one of a steering operation of a predetermined angle or more or a steering operation of a predetermined torque or more is performed from the steering wheel, A steer-by-wire steering device that performs steering according to a steering operation with priority over an automatic driving system. In an embodiment to be described later, in this configuration, even when the automatic tracking system is operating, when at least one of the steering operation angle or torque is equal to or greater than a predetermined threshold value, the target rotation by the steering operation is performed. By selecting the steering angle as an actual target value, steering according to the steering operation is performed.
[0008]
The present invention can also be configured as a steer-by-wire type steering apparatus that moves a steering wheel in accordance with a steering operation when an automatic driving system is operating. In an embodiment to be described later, this configuration is configured such that when the automatic tracking system is prioritized, the target turning angle by the steering operation from the steering wheel is ignored, and the target turning angle by the automatic tracking system is set as the actual target value. Realized by being selected. That is, since the steering operation from the steering wheel becomes invalid, even if the steering wheel is moved, the steered wheels can be prevented from being affected.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
≪Steering system configuration and operation outline≫
First, the overall configuration and operation outline of the steering apparatus will be described. FIG. 1 shows a configuration of a steering apparatus according to an embodiment of the present invention. This steering device realizes SBW, and the operation unit 1 which is a driving operation device includes a steering handle 11 as a steering wheel operated by the driver, and the operation amount of the steering handle 11 is processed by the control device 4. And based on this process result, the steering motor 5 of the steering part 2 which is a steering device mechanism is driven, and the steered wheels W and W are steered.
Here, for turning the steered wheels W, W, the rotation of the steering motor 5 is converted into a linear motion of the rack shaft 7 by the ball screw mechanism 9, and this is converted to the turning of the steered wheels W, W via the tie rods 8, 8. This is performed by the steering unit 2 that converts the rudder motion. That is, the linear movement of the rack shaft 7 is performed by the steering motor 5 and the ball screw mechanism 9 which are substituted for the conventional rack and pinion mechanism. Note that the position of the rack shaft 7 during linear motion is detected by a turning angle (steering amount) sensor 10 and fed back to the control device 4.
The operation unit 1 includes a steering handle 11 operated by a driver, a steering shaft 14 that transmits an operation amount of the steering handle 11, an operation amount detection unit 12 that detects an operation amount of the steering handle 11, and an operation of the steering handle 11. And an operation reaction force motor 19 for improving the performance. An operation torque sensor 15 and an operation angle sensor 16 (see FIGS. 2 and 3), which are the operation amount detection means 12, are arranged along the longitudinal direction of the steering shaft 14. Among them, the operation torque sensor 15 is a known sensor using a strain gauge or the like, and detects the amount of torque input from the steering handle 11 to start operation or change the direction of the steered wheels W and W ( Responsiveness at the time of switching). On the other hand, the operation angle sensor 16 is composed of a potentiometer that detects the rotational position of the steering shaft 14 by the operation of the steering handle 11, and outputs the operation angle of the steering handle 11 as a voltage value (detected value θs). The output (detection value θs) from the operation angle sensor 16 is used by the control device 4 to set the actual turning angle (rack position) of the steered wheels W and W. Further, the other end portion of the steering shaft 14 is connected to a rotation shaft of the operation reaction force motor 19. The operation reaction force motor 19 receives a signal from the control device 4, and has a direction different from the operation direction of the steering handle 11 (movement of the steering handle 11) according to the position and operation direction of the steering handle 11 and a predetermined direction. By generating a reaction force of a magnitude (operation reaction force), it has a function of improving the operability and accuracy of the turning operation.
The vehicle speed sensor 22 has a function of outputting the detected vehicle speed detection value to the control device 4. The automatic tracking system 70 is connected to the operation unit 1 and the control device 4 and outputs a target turning angle calculated for performing automatic tracking to the control device 4, and at the time of automatic tracking, the steering handle 11. Has a function of controlling the operation unit 1 in order to fix.
[0011]
FIG. 2 shows a block configuration of the control device according to the embodiment of the present invention. The control device 4 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an ECU (Electronic Control Device) having a predetermined electric circuit, as shown in FIG. The operation unit 1 and the steering unit 2 are electrically connected via a harness that is a signal transmission cable.
The control device 4 receives the detected values from the operation angle sensor 16, the operation torque sensor 15, and the vehicle speed sensor 22 of the operation unit 1, and the steering control unit 31 that drives the steering motor 5, and the operation reaction force of the operation unit 1. An operation reaction force control unit 32 that controls the motor 19 is configured. The operation angle sensor 16 Or The operation torque sensor 15 constitutes the operation amount detection means 12 (see FIG. 1).
[0012]
The turning control unit 31 sets a target turning angle setting unit 34 for setting the turning angle target value θt of the steered wheels W, and the turning angle target value θt and the current value detected by the turning angle sensor 10. A deviation calculating section 35 for calculating a deviation value of the turning angle from the actual turning angle θr, and a control output signal Ds (direction signal + PWM signal) for driving the steering motor 5 corresponding to the deviation amount (deviation amount signal Drs). ), A steering motor drive circuit 37 that generates a drive signal Ss for driving the steering motor 5 based on the control output signal Ds, and a torque detection value Ts of the operation torque sensor 15. The FF control unit 38 performs FF control by outputting a control signal Fcs to the steering motor control signal output unit 36 on the basis thereof. The target turning angle setting unit 34 determines a target turning angle, determines a target turning angle signal θm based on the target turning angle, further performs processing according to the vehicle speed V on the target turning angle signal θm, and corrects the target turning angle. The steering angle θt is output.
The operation reaction force control unit 32 acquires a target operation reaction force setting unit 39 that determines a target reaction force to be applied to the steering handle 11, and a target reaction force signal Tms output from the target operation reaction force setting unit 39. An operation reaction force motor control signal output unit 40 that outputs a control signal Mcs for driving the reaction force motor 19 and an operation reaction that outputs a drive signal Ms for driving the operation reaction force motor 19 based on the control signal Mcs. And a force motor drive circuit 41.
[0013]
FIG. 3 shows a block configuration of the target turning angle setting unit according to the embodiment of the present invention. The target turning angle setting unit 34 includes a target turning angle calculation unit 51, a target turning angle selection unit 52, and a vehicle speed correspondence correction unit 53. The target turning angle calculation unit 51 searches the map using the detected value θs input from the operation angle sensor 16 as an address, determines the target turning angle, and determines the target turning angle signal θh based on this. The target turning angle selection unit 52 selects either the target turning angle signal θj input from the automatic tracking system 70 or the target turning angle signal θh input from the target turning angle calculation unit 51, and finally Is output as a target turning angle signal θm. Details will be described later. The vehicle speed correction unit 53 corrects the target turning angle signal θm input from the target turning angle selection unit 52 by performing a predetermined calculation process according to the vehicle speed V input from the vehicle speed sensor 22 and the correction result. The corrected target turning angle θt is output to the deviation calculator 35.
The automatic tracking system 70 outputs the target turning angle θj and the operating signal to the target turning angle selection unit 52 and outputs the operating signal to the deviation calculation unit 35.
[0014]
FIG. 4 shows a block configuration of the automatic tracking system according to the embodiment of the present invention. The automatic tracking system 70 includes a preceding vehicle recognition unit 71 and an automatic tracking control unit 72. Whether or not the preceding vehicle recognition unit 71 recognizes the preceding vehicle traveling in front of the vehicle by an image processing function or the like and recognizes the preceding vehicle to the driver through the preceding vehicle recognition display unit 81. Notify The contents are also output to the automatic tracking control unit 72. The automatic tracking control unit 72 determines whether or not to perform automatic tracking based on information from the preceding vehicle recognition unit 71 and the automatic tracking switch 82, and performs an automatic tracking operation based on the determination result. The driver refers to the preceding vehicle recognition display unit 81 and activates the automatic tracking system 70 by setting the automatic tracking switch 82 in accordance with the driver's intention if the vehicle is in the “front vehicle recognition” state. Can do. If it is not in the “front vehicle recognition” state, the automatic tracking system 70 does not operate even if the automatic tracking switch 82 is set. Further, the driver can release the automatic tracking system 70 once activated by resetting the automatic tracking switch 82. The automatic follow-up switch 82 is a change-over switch that can be set and reset at any time.
[0015]
≪Operation of automatic tracking system≫
Next, the operation of the automatic tracking system connected to the steering device will be described. FIG. 5 is a flowchart showing the operation of the automatic tracking control unit 72. Hereinafter, the description will be made with reference to FIGS. 4 and 5 (see FIG. 1 and the like as appropriate). In the automatic tracking system 70, the automatic tracking control unit 72 operates automatically based on the acquired information while acquiring output information from the preceding vehicle recognition unit 71 and the automatic tracking switch 82 at a predetermined cycle. Follow-up is achieved. First, the automatic tracking control unit 72 checks whether or not the preceding vehicle recognition unit 71 has “recognition of the preceding vehicle” (step S101). If there is “recognition of the preceding vehicle” (Yes in step S101), it is checked whether or not the preceding vehicle has been recognized (step S102). If the recognition is completed (Yes in step S102), the preparation for the automatic follow-up system operation is completed, and the preceding vehicle recognition display unit 81 displays “ By displaying "preceding vehicle recognition" (step S103), the driver is informed that "preceding vehicle recognition is complete". The driver determines whether or not to activate the automatic tracking system 70 when “previous vehicle recognition” is displayed on the preceding vehicle recognition display unit 81, and determines that the automatic tracking system 70 should be activated. 82 is set. The driver resets the automatic tracking switch 82 when releasing the automatic tracking system 70 once activated.
[0016]
The automatic tracking control unit 72 displays “recognition of preceding vehicle” (step S103), and then checks whether or not the automatic tracking switch 82 is turned on (step S104). If it is on (Yes in step S104), it operates to perform automatic tracking. Specifically, first, the target turning angle θj is calculated and output to the target turning angle setting unit 34 of the control device 4 (step S105). This target turning angle θj means the angle of the steered wheels W and W that are optimal at that time in order to follow the preceding vehicle recognized by the preceding vehicle recognition unit 71. Next, an “active signal” indicating that the automatic tracking system 70 is operating is set (step S106). This signal is also output to the target turning angle setting unit 34 of the control device 4. Then, the rotation ratio between the steering angle of the steering handle 11 in the operation unit 1 and the steered wheels W and W in the steered unit 2 can be changed (step S107). Specifically, the automatic follow-up control unit 72 outputs an operating signal to the deviation calculation unit 35 of the steering control unit 31. The deviation calculating unit 35 having received the operating signal processes the value obtained by dividing the turning angle θr by P as the new turning angle θr when the turning angle θr is input from the turning angle sensor 10. . P indicates a ratio between a value at the time of automatic driving and a normal value (= value at the time of automatic driving / normal value) of the rotation ratio of the turning angle to the steering angle. It is assumed that P is a value larger than 1, and the larger the value is, the larger the operation of the turning angle with respect to the steering angle is compared to the normal time. In other words, as P becomes larger, the change in the steering angle due to the reaction force with respect to the turning angle becomes smaller as compared with the normal time. By such control, the reaction force transmitted to the steering handle 11 by the operation of the steered wheels W, W is reduced during the operation of the automatic tracking system 70, so that the movement of the steering handle 11 during automatic driving is reduced. Can do. It is assumed that the value of the ratio P is given in advance to the deviation calculator 35. Another specific example of step S107 will be described in << Operation of target turning angle selection unit >> described later.
[0017]
When the preceding vehicle recognition unit 71 does not recognize the preceding vehicle (No in step S101) or when the preceding vehicle recognition is not completed (No in step S102), the automatic tracking system is activated. This means that preparation is not completed, and “preceding vehicle recognition” is not displayed on the preceding vehicle recognition display unit 81 via the preceding vehicle recognition unit 71 (step S108). Here, if the “recognition of preceding vehicle” is displayed, the display is turned off. Next, the automatic tracking switch 82 is reset (step S109). Further, the signal during operation of the automatic tracking system is reset (step S110), and the operation reaction force motor 19 is controlled so that the steering handle 11 is brought into a normal state (step S111). In step S104, if the automatic tracking switch 82 is not on (No in step S104), the driver does not operate the automatic tracking system even when the preceding vehicle recognition unit 71 is in the “front vehicle recognition” state. Therefore, the operation signal is reset (step S110) and the rotation ratio between the steering angle and the turning angle is normalized (step S111). The contents of normalization of the rotation ratio will be described in << Operation of target turning angle selection unit >> described later.
As described above, the automatic follow-up system 70 is realized by the automatic follow-up control unit 72 periodically repeating the operation shown in the flowchart of FIG.
[0018]
≪Operation of target turning angle selection part≫
Next, details of the operation of the target turning angle selection unit will be described. FIG. 6 is a flowchart showing the operation of the target turning angle selection unit. Hereinafter, description will be made with reference to FIGS. 3 and 6 (see FIG. 1 and the like as appropriate). The target turning angle selection unit 52 is in the target turning angle setting unit 34 of the control device 4 and performs a process of selecting the target turning angle θm at that time, and the process is performed at a predetermined cycle. Done every time. Thereby, it switches to the driving | running | working by an automatic follow-up system or a steering handle operation according to an occasional state. First, the target turning angle selection unit 52 looks at the operating signal from the automatic tracking system 70 (step S201). Here, if the operating signal is on (Yes in step S201), it is checked whether or not the operation torque Ts from the operation torque sensor 15 is equal to or higher than a threshold value giving priority to the operation of the steering wheel 11 (step). S202). If the operation torque Ts is not equal to or greater than the threshold value (No in step S202), it is checked whether the operation angle θs from the operation angle sensor 16 is equal to or greater than the threshold value (step S203). If the operation angle θs is not equal to or greater than the threshold value (No in step S203), the automatic tracking system 70 is prioritized, and the final target turning angle θm is input from the automatic tracking system 70. The steering angle θj is set (step S204).
On the other hand, when the automatic tracking system 70 is not operating (No in Step S201), the final target turning angle θm is set as the target turning angle θh input from the target turning angle calculation unit 51 (Step S206). . The operation in step S206 corresponds to normalization of the rotation ratio between the steering angle and the turning angle in step S111 in FIG.
Further, when the operation torque Ts is equal to or greater than the threshold value (Yes in step S202) or the operation angle θs is equal to or greater than the threshold value (Yes in step S203), the automatic tracking system 70 is in operation. Will give priority to the operation of the steering wheel 11, and the final target turning angle θm is set to a value obtained by multiplying the target turning angle θh input from the target turning angle calculation unit 51 by P (step S205). ). That is, θm = θh × P. Here, P indicates a ratio between a value at the time of automatic driving and a normal value (= value at the time of automatic driving / normal value) among the rotation ratio of the turning angle to the steering angle. It is assumed that P is a value larger than 1, and the larger the value is, the larger the operation of the turning angle with respect to the steering angle is compared to the normal time. By performing such control, when the automatic operation by the automatic follow-up system 70 is switched to the normal operation by the steering handle 11, a small number of steering handles 11 are obtained when the difference between the positions of the steering handle 11 and the steered wheels W and W is large. The position difference can be eliminated by the operation of. In this case, when the position of the steering handle 11 and the positions of the steered wheels W and W coincide, the ratio P may be set to 1, that is, the normal ratio may be restored. The operation in step S205 is a specific example of changing the rotation ratio between the steering angle and the turning angle in step S107 in FIG.
During normal steering wheel operation, the ratio P = 1, and θm = θh as shown in step S206. Further, the threshold value of the operating torque used in step S202, the threshold value of the operating angle used in step S203, and the value of P used in step S206 are given in advance to the target turning angle selector 34. And
[0019]
<< Other Embodiments >>
An example of the preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, the following embodiments can be considered.
(1) In the embodiment described above, both the operation angle and the operation torque are described so as to check the magnitude relationship with the threshold value, but either one may be checked.
(2) In the above embodiment, the automatic tracking system is reset when the preceding vehicle cannot be recognized, or when the driver performs a reset operation of the automatic tracking switch. It may be reset when the target steering angle is set to the target value by the steering wheel operation. That is, the automatic tracking system may be canceled when the steering wheel operation becomes valid during automatic tracking. (In the above-described embodiment, during the operation of the automatic tracking system, even if the steering wheel operation is given priority once the recognition of the preceding vehicle is continued and the automatic tracking switch is not reset by the driver, the predetermined range If you return to the steering wheel operation, the automatic tracking system will be given priority again.)
(3) In the above-described embodiment, the rotation ratio between the steering angle and the turning angle can be changed in step S107 in the flowchart of FIG. 5, but the position of the steering handle 11 may be fixed instead. Good. In this case, specifically, the automatic follow-up control unit 72 issues an instruction “fix steering handle” to the operation reaction force motor 19 of the operation unit 1. The operation reaction force motor 19 that has received the instruction controls the steering handle 11 so that it does not rotate unless the steering handle 11 is operated above the threshold value as described above. The fixed position of the steering handle 11 may be a neutral position or a position at the time when the automatic tracking system 70 starts to operate. Thereby, the steering wheel does not move during the automatic driving system operation regardless of the driver's intention, and the driver's uncomfortable feeling can be reduced.
(4) In the above-described embodiment, the automatic tracking system that directly recognizes the preceding vehicle is described as the automatic driving system. However, another automatic tracking system or another automatic driving system may be used.
(5) In the embodiment, the threshold value is set by software. However, the threshold value may be set mechanically by using, for example, a spring. The threshold value is set to a value that prevents the steering wheel from moving due to, for example, a road bump.
(6) Although the steering wheel is shown as a round steering handle in the embodiment, it may be a joystick.
[0020]
【The invention's effect】
According to the first aspect of the present invention, when the automatic driving system is in operation, the change in the steering angle due to the reaction force with respect to the turning angle can be reduced, so it is not related to the driver's intention. The movement of the steering wheel is reduced, and the driver's uncomfortable feeling can be reduced.
[0021]
According to the second aspect of the present invention, when the automatic driving system is operating, when at least one of a steering operation at a predetermined angle or more or a steering operation at a predetermined torque or more is performed from the steering wheel, Since the steering according to the steering operation is performed with priority over the driving system, the steering operation by the driver can be made effective when an obstacle or an emergency situation is encountered. In other words, if there is a steering operation less than a predetermined angle or less than a predetermined torque, the automatic driving system has priority, so even if there is an erroneous steering operation by the driver, automatic driving is not canceled It will be.
[0022]
Further, according to the above invention, by increasing the movement of the steering angle with respect to the steering angle, the steering can be performed with a small steering operation, so that the transition from the automatic operation to the normal operation by the steering operation can be smoothly performed. Therefore, it is possible to reduce the driver's uncomfortable feeling.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a steering apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control device according to an embodiment of the present invention.
FIG. 3 is a diagram showing a block configuration of the automatic tracking system according to the embodiment of the present invention.
FIG. 4 is a diagram showing a block configuration of a target turning angle setting unit according to the embodiment of the present invention.
FIG. 5 is a flowchart showing the operation of the automatic tracking control unit according to the embodiment of the present invention.
FIG. 6 is a flowchart showing an operation of a target turning angle setting unit according to the embodiment of the present invention.
[Explanation of symbols]
1 ... operation part
2 ... Steering part
4. Control device
5 ... Steering motor
7 ... Rack shaft
8, 8 ... Tie rod
9 ... Ball screw mechanism
10 ... Steering angle sensor
11 ... Steering handle
12 ... Manipulation amount detection means
14 ... Steering shaft
19 ... Operation reaction motor
22 ... Vehicle speed sensor
31 ... Steering control unit
32. Operation reaction force control unit
34 ... Target turning angle setting section
51. Target turning angle calculation unit
52 ... Target turning angle selection section
70 ... Automatic tracking system
P: The ratio between the value at the time of automatic operation and the normal value in the rotation ratio of the turning angle to the steering angle
W, W ... steered wheel

Claims (2)

A steer-by-wire steering device in which a vehicle driving operation device and a steering device mechanism are mechanically separated,
It is mounted on a vehicle equipped with an automatic driving system that outputs the target turning angle ,
When the automatic driving system is in operation, the steering wheel mechanism of the vehicle is steered by controlling the steering device mechanism based on the target turning angle, and the steering angle and the steering in the driving operation device are controlled. A steer-by-wire type steering apparatus comprising means for changing a rotation ratio with a turning angle in the apparatus mechanism. When the automatic driving system is operating,
When at least one of a steering operation over a predetermined angle or a steering operation over a predetermined torque is performed from the steering wheel,
The steer-by-wire type steering apparatus according to claim 1, wherein steering is performed according to a steering operation with priority over the automatic driving system.

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