JP2011000963A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform highly reliable steer-by-wire steering operation while reducing the cost of a device.SOLUTION: In the steering device, a relative rudder angle is obtained by a resolver for controlling rotation of a steering reaction motor and/or a resolver for controlling rotation of a turning motor, a reference value deciding part decides on a reference value of the obtained relative rudder angle when a straight moving state determining part determines that the vehicle is in a straight driving state, and an absolute rudder angle calculating part calculates an absolute rudder angle by accumulating a relative rudder angle obtained with the decided reference value as a start point.

Description

  The present invention relates to a steer-by-wire type steering apparatus including a steering reaction force motor that applies a steering reaction force to a steering wheel and a steering motor that steers a steered wheel, and in particular, reduces the apparatus cost. The present invention also relates to a steering apparatus that can perform highly reliable steer-bye steering.

  Conventionally, a steer-by-wire system that eliminates mechanical coupling between a steering wheel and a steered wheel such as a front wheel has been proposed as a steering system for vehicles such as automobiles (see, for example, Patent Document 1 and Patent Document 2).

  This steer-by-wire system eliminates the need for a power transmission shaft or the like that connects the steering handle and the steered wheels, increasing the degree of freedom in arranging the steering member, and the steering angle input to the steering handle and the actual steering angle. The ratio to the turning angle can be set freely.

  By the way, in the steer-by-wire system, the steering-side member and the steering-side member are mechanically separated, so the steering-side steering angle that is input to the steering handle and the steering-side steering that steers the steered wheels. It is necessary to detect each corner individually.

  For this reason, an absolute steering angle sensor for detecting the absolute steering angle on the steering side is provided on the steering side, and an absolute steering angle sensor for detecting the absolute steering angle on the steering side is provided on the steering side. It is generally performed to individually detect the angle and the absolute steering angle on the steered side.

JP 2006-290136 A JP 2006-193083 A

  However, since the absolute rudder angle sensor is expensive, if the absolute rudder angle sensor is provided on each of the steering side and the steered side, there is a problem that the cost of the steering device is increased. There is also a problem that the steer-by-wire steering cannot be continued when the absolute steering angle sensor fails.

  For these reasons, it has become a major issue how to realize a steering device that can perform highly reliable steer-bye steering while reducing the device cost.

  The present invention has been made to solve the above-described problems caused by the prior art, and an object of the present invention is to provide a steering device capable of performing a reliable steer-bye steering while reducing the device cost. And

  In order to solve the above-described problems and achieve the object, the present invention provides a steer including a steering reaction force motor that applies a steering reaction force to a steering handle and a steering motor that steers a steered wheel. It is a by-wire steering device, and includes a straight-running state determining means for determining whether or not the vehicle is in a straight-running state, a resolver for controlling the rotation of the steering reaction force motor, and / or the rotation of the steering motor. Relative rudder angle obtaining means for obtaining a relative rudder angle from a resolver to be controlled, and the relative rudder angle obtained by the relative rudder angle obtaining means when the straight traveling state determining means determines that the vehicle is in a straight traveling state. An absolute steering angle is calculated by integrating a reference value determination means for determining a reference value and a relative steering angle acquired by the relative steering angle acquisition means starting from the reference value determined by the reference value determination means. Characterized by comprising the absolute steering angle calculating means.

  According to the present invention, it is determined whether or not the vehicle is traveling straight, and a relative steering angle is acquired from a resolver that controls the rotation of the steering reaction force motor and / or a resolver that controls the rotation of the steering motor. When it is determined that the vehicle is traveling straight, the reference value of the acquired relative rudder angle is determined and then the absolute rudder angle is integrated by integrating the acquired relative rudder angle with the determined reference value as the starting point. Since the angle is calculated, the absolute rudder angle is calculated by integrating the relative rudder angle with the relative rudder angle in the straight running state as the reference value, so use the absolute rudder angle sensor. And a highly accurate absolute rudder angle can be obtained. Therefore, it is possible to perform steer-bye steering with high reliability while reducing the device cost.

FIG. 1 is a diagram showing an outline of a steering method according to the present invention. FIG. 2 is a block diagram illustrating a configuration of the steering device according to the present embodiment. FIG. 3 is a diagram for explaining the absolute steering angle calculation process. FIG. 4 is a diagram illustrating an example of a straight traveling state determination condition. FIG. 5 is a flowchart showing a processing procedure executed by the steering device. FIG. 6 is a view showing a modified example of a combination of a motor resolver or an absolute steering angle sensor. FIG. 7 is a flowchart showing a processing procedure when the sensor value of the absolute steering angle sensor is monitored.

  Embodiments of a steering apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In the following, an outline of the steering method according to the present invention will be described with reference to FIG. 1, and then an embodiment of a steering apparatus to which the steering method according to the present invention is applied will be described.

  First, the outline of the steering method according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an outline of a steering method according to the present invention. As shown in the figure, the steer-by-wire steering system includes a clutch 1c that mechanically separates a steering-side unit including the steering handle 1a and a steered-side unit including the steered wheels 1b. It is normal.

  Specifically, in a state where the clutch 1c is disengaged, the steering side unit and the steered side unit are mechanically separated, and a steer-by-wire state in which each operates independently is set. On the other hand, in a state where the clutch 1c is connected, the steering side unit and the steered side unit are mechanically connected, and therefore, it can operate as a normal power steering state. The power steering state serves as a backup for the steer-by-wire state.

  Hereinafter, a state where the clutch 1c is disengaged, that is, a case where the steering device operates in the steer-by-wire state will be described. A steering side motor 2 for applying a reaction force to the steering handle 1a is provided on the steering side, and a steering side motor 3 for operating the steered wheels 1b is provided on the steering side. Yes.

  Here, conventionally, in order to detect the steering side steering angle input to the steering handle 1a, a steering side absolute steering angle sensor is provided on the steering side, and the steering side absolute steering angle is provided on the steering side. A sensor was provided. However, since these absolute steering angle sensors are expensive, they have been a factor that increases the cost of the steer-by-wire steering device.

  Therefore, in the steering method according to the present invention, instead of providing an absolute steering angle sensor, a resolver (hereinafter referred to as “motor resolver”) used for rotation control of a motor (steering side motor 2 or steered side motor 3) is described. ) To calculate the absolute rudder angle.

  Here, since the motor resolver is used for rotation control of the multiphase motor, the steering angle can be detected with high accuracy. However, since the detected steering angle is a relative angle, the steering angle cannot be used as it is for steer-by-wire steering.

  For example, in the case of a four-phase motor, the motor resolver performs control over 90 degrees for each of the four phases while the motor shaft rotates once (360 degrees). In this case, the steering angle that can be acquired from the motor resolver is in the range of 0 to 90 degrees.

  Therefore, in the steering method according to the present invention, after obtaining the relative rudder angle from the motor resolver (see (A) in the figure), the straight traveling state of the vehicle is detected and the reference value of the relative rudder angle is determined. (See (B) of the figure).

  Then, the absolute rudder angle was calculated based on the determined reference value (see (C) in the figure). Specifically, the absolute rudder angle is calculated by integrating the relative rudder angles acquired from the motor resolver with reference to the reference value determined in FIG.

  In FIG. 1, the absolute steering angle on the steering side is calculated using the motor resolver of the steering side motor 2, and the absolute steering angle on the steering side is obtained with the steering side absolute steering angle sensor. Yes.

  However, the present invention is not limited to this, and the absolute rudder angle on the steered side may be calculated using the motor resolver of the steered side motor 3 after omitting the steered side absolute rudder angle sensor on the steered side. . By doing so, steer-by-wire steering can be performed without using an expensive absolute steering angle sensor.

  Moreover, it is good also as using together the absolute rudder angle sensor and the absolute rudder angle calculation by a motor resolver. In this way, it is possible to monitor the presence or absence of a failure of the absolute rudder angle sensor. When the absolute rudder angle sensor breaks down, steer-by-wire steering is performed using the absolute rudder angle based on the motor resolver. It is possible to continue. Details of this point will be described later with reference to FIG.

  Below, the Example about the steering device to which this steering method is applied is described in detail. In the following, a case where the absolute steering angle on the steering side is calculated using a motor resolver that performs rotation control of the steering side motor 2 will be described.

  FIG. 2 is a block diagram illustrating a configuration of the steering apparatus 10 according to the present embodiment. As shown in the figure, the steering apparatus 10 includes a vehicle sensor 11, a motor resolver 12, a backup mechanism 13, a control unit 14, and a storage unit 15.

  In addition, the control unit 14 includes a startup processing unit 14a, a straight traveling state determination unit 14b, a reference value determination unit 14c, an absolute steering angle calculation unit 14d, a steer-by-wire processing unit 14e, and an end-time processing unit 14f. It has more. And the memory | storage part 15 memorize | stores the reference value 15a and the end time relative steering angle 15b.

  The vehicle sensor 11 is a vehicle motion detection sensor such as a vehicle speed sensor, a yaw rate sensor, or a lateral G (G) sensor, and passes each acquired sensor value to the straight traveling state determination unit 14 b of the control unit 14. Each sensor value is used when the straight traveling state determination unit 14b determines whether or not the vehicle is in a straight traveling state. The vehicle sensor 11 may include a GPS (Global Positioning System) sensor or an acceleration sensor.

  The motor resolver 12 is a resolver for controlling the rotation of the steering side motor 2 shown in FIG. 1 and performs a process of passing the detected relative steering angle to the control unit 14. In this embodiment, the resolver of the steering side motor 2 is used as the motor resolver 12, but the resolver of the steered side motor 3 may be used as the motor resolver 12.

  The backup mechanism 13 is a mechanism for mechanically connecting the steering side unit shown in FIG. 1 and the steered side unit, and includes, for example, the clutch 1c shown in FIG. In this case, the backup mechanism 13 is activated by performing the control for connecting the clutch 1c, and the backup mechanism 13 is deactivated by performing the control for disengaging the clutch.

  The control unit 14 receives the relative rudder angle from the motor resolver 12, determines the reference value of the relative rudder angle when the straight traveling state of the vehicle is detected, and integrates the relative rudder angle with respect to the determined reference value. It is a process part which performs the process which calculates a steering angle. The control unit 14 is also a processing unit that performs a startup process and an end process of the steering device 10.

  The startup processing unit 14 a is a processing unit that operates when the steering device 10 is started up, and compares the relative steering angle received from the motor resolver 12 with the end relative steering angle 15 b read from the storage unit 15. Then, a process of determining whether the straight-ahead state is determined to determine a new reference value 15a or to use the reference value 15a of the storage unit 15 as it is is performed.

  Specifically, when the difference between the startup relative steering angle received from the motor resolver 12 or the end relative steering angle 15b is less than a predetermined value, the startup processing unit 14a stores the storage unit 15. The absolute steering angle calculation unit 14d is instructed to calculate the absolute steering angle using the reference value 15a stored in the above. On the other hand, when the difference is greater than or equal to a predetermined value, the directing state determination unit 14b is instructed to perform the straight traveling state determination.

  When the difference from the end relative steering angle 15b is greater than or equal to a predetermined value, the steering handle 1a is operated after the steering device 10 is ended, or the steering angle of the steered wheels 1b is changed due to an external factor. Refers to the case. In such a case, if the reference value 15a at the end is used, the steering-side steering angle and the steering-side steering angle are relatively shifted from each other. Therefore, it is necessary to newly determine the reference value 15a.

  The straight traveling state determination unit 14b is a processing unit that determines whether or not the vehicle is in a straight traveling state based on the vehicle speed, yaw rate, lateral G, and the like received from the vehicle sensor 11. Further, when it is determined that the vehicle is in the straight traveling state, the straight traveling state determination unit 14b notifies the reference value determination unit 14c to that effect.

  In addition, although the figure has illustrated the case where the straight traveling state determination unit 14b operates based on an instruction from the activation processing unit 14a, the timing at which the straight traveling state determination unit 14b determines the straight traveling state is other than at the time of activation. Any timing may be used. The straight-running state determination condition used by the straight-running state determination unit 14b will be described later with reference to FIG.

  The reference value determination unit 14c performs a process of storing the relative steering angle from the motor resolver 12 at the timing when the notification that the vehicle is in the straight traveling state is received from the straight traveling state determination unit 14b in the storage unit 15 as the reference value 15a. It is a processing unit. The reference value 15a includes a relative steering angle from the motor resolver 12 and a steered side absolute steering angle corresponding to the relative steering angle.

  The absolute rudder angle calculation unit 14d is a processing unit that performs processing for calculating the absolute rudder angle by integrating the relative rudder angle from the motor resolver 12 with the reference value 15a read from the storage unit 15 as a reference. The absolute rudder angle calculation unit 14d also performs a process of notifying the steer-by-wire processing unit 14e of the calculated absolute rudder angle as needed. The details of the absolute steering angle calculation process performed by the absolute steering angle calculation unit 14d will be described later with reference to FIG.

  The steer-by-wire processing unit 14e is a processing unit that performs steer-by-wire steering based on the absolute steering angle received from the absolute steering angle calculation unit 14d. The steer-by-wire processing unit 14e also performs a process of separating the backup mechanism 13 when steer-by-wire steering is started.

  When the steering device 10 receives an end instruction, for example, when the ignition switch is turned off, the end-time processing unit 14f is a processing unit that performs a matching process between the steering-side steering angle and the steering-side steering angle. . In addition, after the coincidence process, the end-time processing unit 14f also performs a process of storing the relative steering angle from the motor resolver 12 in the storage unit 15 as the end-time relative steering angle 15b.

  Then, the processing unit 14f at the end performs a process of connecting the backup mechanism 13 following the process of matching the steering-side steering angle and the steering-side steering angle and the storage process of the end-side relative steering angle 15b. Note that the connection processing of the backup mechanism 13 may be performed by the startup processing unit 14a.

  The memory | storage part 15 is a memory | storage part comprised with memory | storage devices, such as a hard disk drive and a non-volatile memory, and memorize | stores the reference value 15a and the end time relative steering angle 15b. Since reference value 15a and end relative steering angle 15b have already been described, description thereof will be omitted here.

  Next, the detailed content of the absolute steering angle calculation process performed by the absolute steering angle calculation unit 14d will be described with reference to FIG. FIG. 3 is a diagram for explaining the absolute steering angle calculation process. Note that (A) in the figure shows the detection angle (relative rudder angle) by the motor resolver 12, (B) in the figure shows a counter used for integrating the relative rudder angle, and (C) in the figure. Shows the calculated absolute steering angle.

  As shown in FIG. 3A, the detected angle (relative steering angle) by the motor resolver 12 takes a maximum value at point A4 and takes a value of 0 at point A1. And it changes linearly toward the point A2, takes the maximum value again at the point A2, and takes the value 0 again at the point A5. For example, when the motor is a four-phase motor, the detection angle (relative rudder angle) linearly increases or decreases in the range of 0 degrees to 90 degrees.

  Here, as shown in FIG. 3A, when the point A3 is the reference value detection position, as shown in FIG. 3B, the counter in the section from the point A1 to the point A2 is used. Is “0”. The counter for the section including the point A5 is “+1”, and the counter for the section including the point A4 is “−1”. The counter changes as “+1” and “+2” in the positive direction and “−1” and “−2” in the negative direction.

  By doing so, the absolute steering angle shown in FIG. 3C is calculated. That is, the absolute rudder angle of the point C3 corresponding to the point A3 is set to 0, and “the maximum value of the relative rudder angle × the counter value” is added to each line segment (for example, the line shown in FIG. 3A). By connecting the minutes A1A2), the absolute steering angle can be calculated.

  For example, a point C1 shown in FIG. 3C is a point A1 and a point A4 shown in FIG. 3A, and a point C2 shown in FIG. 3C is a point A in FIG. Correspond to point A2 and point A5 shown in FIG.

  Next, an example of the straight traveling state determination condition used by the straight traveling state determination unit 14b will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a straight traveling state determination condition. Hereinafter, each condition is described as a condition A and a condition B using A to D shown in FIG.

  Condition A is a condition that the vehicle speed is greater than a predetermined threshold. Thus, the condition for the vehicle speed is provided because when the vehicle speed is low, the straight traveling state and the non-linear state are easily interchanged and it is difficult to accurately detect the straight traveling state.

  The condition B is a condition that the yaw rate is smaller than a predetermined threshold, and the condition C is a condition that the lateral G (Gee) is smaller than the predetermined threshold. Further, the condition D is a condition that the amount of change in the steering angle is smaller than a predetermined threshold value. Note that, in the condition D, the relative steering angle acquired from the motor resolver 12 or the absolute steering angle calculated by the absolute steering angle calculation unit 14d is compared with a predetermined threshold value.

  Thus, the straight-running state determination unit 14b can determine that the vehicle is in the straight-running state when all of the conditions A to D are satisfied. In addition, after satisfy | filling the condition A, when satisfy | filling any one or two of the conditions B-condition D, it is good also as determining with the vehicle being in a straight-ahead state.

  In addition, in the determination of the satisfaction of each condition described above, it may be determined that each condition is satisfied when each condition is satisfied over a predetermined elapsed time, or each condition is satisfied when each condition is instantaneously satisfied. It may be determined that is established.

  Next, a processing procedure executed by the steering device 10 will be described with reference to FIG. FIG. 5 is a flowchart showing a processing procedure executed by the steering device 10. As shown in the figure, the startup processing unit 14a calculates a difference between the end relative steering angle 15b and the startup relative steering angle (step S101), and whether or not the calculated difference is smaller than a predetermined threshold value. Is determined (step S102).

  If the difference is smaller than the predetermined threshold (step S102, Yes), the reference value 15a stored in the storage unit 15, that is, the reference value 15a stored when the steering device 10 is ended is used (step S102). S103).

  On the other hand, when the determination condition of step S102 is not satisfied (step S102, No), the straight traveling state determination unit 14b determines whether the straight traveling condition is satisfied (step S104).

  When the straight traveling condition is satisfied (step S104, Yes), the reference value determination unit 14c determines the reference value 15a (step S105). If the determination condition in step S104 is not satisfied (No in step S104), the process in step S104 is repeated.

  Subsequently, the absolute steering angle calculation unit 14d calculates the absolute steering angle by integrating the relative steering angles from the motor resolver 12 based on the reference value 15a (step S106). Then, the steer-by-wire processing unit 14e cuts the backup mechanism 13 (step S107) and starts steer-by-wire steering (step S108).

  Then, the end-time processing unit 14f determines whether or not there is an end request (step S109). If there is an end request (step S109, Yes), the steering-side steering angle and the steering-side steering angle are determined. (Step S110), the end steering angle (end relative steering angle 15b) and the reference value 15a are stored in the storage unit 15 (Step S111).

  Subsequently, the termination time processing unit 14f connects the backup mechanism 13 (step S112), and terminates the processing. If the determination condition in step S109 is not satisfied (step S109, No), the process in step S109 is repeated.

  By the way, although the absolute steering angle sensor on the steering side has been eliminated so far, the steering side absolute steering angle has been described based on the relative steering angle acquired from the motor resolver of the steering side motor 2. A motor resolver of the steered side motor 3 may be used. Moreover, it is good also as coexisting the absolute steering angle acquisition by an absolute steering angle sensor, and the absolute steering angle calculation by a motor resolver.

  Therefore, these modified examples will be described below. FIG. 6 is a view showing a modified example of a combination of a motor resolver or an absolute steering angle sensor. For example, as shown in FIG. 6A, after the steering side absolute steering angle sensor is eliminated, the steering side absolute steering angle is calculated using the motor resolver of the steering side motor 3. Good. Thus, the cost of the steering device 10 can be further reduced by eliminating the steering-side absolute rudder angle sensor.

  Further, as shown in FIG. 6B, in addition to FIG. 6A, a steering side absolute steering angle sensor and a steering side absolute steering angle sensor are provided, respectively, and the absolute steering angle by the absolute steering angle sensor is provided. The calculation and the absolute steering angle calculation by the motor resolver may coexist.

  By doing in this way, it becomes possible to monitor the absolute steering angle acquired by the absolute steering angle sensor with the absolute steering angle calculated based on the motor resolver. For example, if the difference between the absolute rudder angle acquired by the absolute rudder angle sensor and the absolute rudder angle calculated based on the motor resolver exceeds a predetermined threshold, the absolute rudder angle sensor is regarded as a failure and the motor resolver is Steer-by-wire steering can be continued using the absolute rudder angle calculated based on this.

  Next, a processing procedure executed by the steering device 10 in the configuration shown in FIG. 6B will be described with reference to FIG. FIG. 7 is a flowchart showing a processing procedure when the sensor value of the absolute steering angle sensor is monitored. As shown in the figure, the absolute rudder angle from the absolute rudder angle sensor is normally used (step S201).

  Then, the absolute steering angle based on the motor resolver is calculated (step S202), and the sensor output is monitored using the absolute steering angle based on the motor resolver (step S203). When the sensor value is abnormal (step S204, Yes), the absolute steering angle based on the motor resolver is used instead of the absolute steering angle from the absolute steering angle sensor (step S205).

  And after performing an alerting | reporting process about abnormality of an absolute steering angle sensor (step S206), a process is complete | finished. In addition, when the determination condition of step S204 is not satisfied (step S204, No), the processing after step S202 is repeated.

  As described above, in this embodiment, a relative steering angle is obtained from a resolver that controls the rotation of the steering reaction force motor and / or a resolver that controls the rotation of the steering motor, and the vehicle is When it is determined that the vehicle is in the straight traveling state, the reference value determination unit determines the reference value of the acquired relative steering angle, and then the absolute steering angle calculation unit is acquired using the determined reference value as a starting point. The steering device was configured to calculate the absolute rudder angle by integrating the relative rudder angle. Therefore, it is possible to perform steer-bye steering with high reliability while reducing the device cost.

  As described above, the steering apparatus according to the present invention is useful when it is desired to perform steer-by-wire steering at a low cost. In particular, the steering side absolute steering angle or the steering side absolute steering angle is detected with high accuracy. It is suitable when you want to perform highly reliable steering.

DESCRIPTION OF SYMBOLS 1a Steering handle 1b Steering wheel 1c Clutch 2 Steering side motor 3 Steering side motor 10 Steering device 11 Vehicle sensor 12 Motor resolver 13 Backup mechanism 14 Control part 14a Starting time process part 14b Straightness state determination part 14c Reference value determination part 14d Absolute steering Angle calculation unit 14e Steer-by-wire processing unit 14f End processing unit 15 Storage unit 15a Reference value 15b End relative steering angle

Claims (5)

A steer-by-wire steering device including a steering reaction force motor for applying a steering reaction force to a steering handle and a steering motor for turning a steered wheel,
Straight-running state determining means for determining whether or not the vehicle is in a straight-running state;
A relative steering angle acquisition means for acquiring a relative steering angle from a resolver that controls the rotation of the steering reaction force motor and / or a resolver that controls the rotation of the steering motor;
A reference value determining means for determining a reference value of the relative steering angle acquired by the relative steering angle acquiring means when it is determined by the straight traveling state determining means that the vehicle is in a straight traveling state;
An absolute rudder angle calculating means for calculating an absolute rudder angle by integrating the relative rudder angles acquired by the relative rudder angle acquiring means starting from the reference value determined by the reference value determining means. Steering device. Before the absolute steering angle was calculated by the absolute steering angle calculation means, a backup mechanism that mechanically connects the steering side and the steering side was enabled, and the absolute steering angle was calculated by the absolute steering angle calculation means. The steering apparatus according to claim 1, further comprising backup control means for disabling the backup mechanism. Storage means for storing the relative steering angle and the reference value when the steering device finishes operation;
The absolute rudder angle calculating means includes
When the difference between the relative steering angle acquired by the relative steering angle acquisition unit and the relative steering angle stored in the storage unit is less than a predetermined value when the steering device is activated, the reference value The steering according to claim 1 or 2, wherein the absolute steering angle is calculated using a reference value stored in the storage means instead of the reference value determined by the determination means as the starting point. apparatus. The backup control means includes
The steering apparatus according to claim 3, wherein when the absolute steering angle calculation means uses the reference value stored in the storage means as the starting point, the backup mechanism is invalidated. When the steering device finishes its operation, the steering reaction force motor or the steering motor is operated to set a ratio between the absolute steering angle on the steering side and the absolute steering angle on the steering side to a predetermined value. A steering angle matching means for matching the value,
The backup control means includes
The steering apparatus according to claim 2, 3 or 4, wherein the backup mechanism is enabled after the ratio is matched with the predetermined value by the rudder angle matching means.

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