Steering

Abstract

A steering device (10) includes a steering shaft (21), a motor (22), a stopper mechanism (40), and a controller (27). The controller (27) is configured to execute a first process and a second process when a certain condition is satisfied. The first process includes operating a steering wheel (11) to a first operation end point and then operating it in reverse to a second operation end point by controlling the motor (22). The second process includes calculating a neutral position of the steering wheel (11) based on the rotation angle of the motor at the time point when the reverse operation of the steering wheel (11) is started and at the time point when the reverse operation of the steering wheel (11) is terminated.

Description

Technical Field

[0001] The invention relates to a steer-by-wire steering device. Background Art

[0002] A so-called steer-by-wire steering device is provided in which a steering wheel and a steering wheel are separated in terms of power transmission. Japanese Unexamined Patent Application Publication No. 2013-252804 (JP 2013-252804 A), for example, provides a steering device including: a reaction force mechanism having a reaction force motor as a source for generating a steering reaction force to be applied to a steering shaft; and a steering mechanism having a steering motor as a source for generating a steering force for steering the steering wheel. When the vehicle is traveling, a controller for the steering device generates a steering reaction force by controlling the power supply to the reaction force motor, and steers the steering wheel by controlling the power supply to the steering motor. Summary of the Invention

[0003] In the steering device according to JP 2013-252804A, a steering motor is controlled based on the steering angle of the steering wheel. The steering device also includes a stopper member for limiting the steering angle of the steering wheel. Therefore, to maintain the positional relationship between the steering wheel and the steering wheels to match a predetermined steering angle ratio, the steering wheel and the steering wheels must be operated with the neutral position of the steering wheel and the neutral position of the steering wheels aligned.

[0004] For example, during steering assembly, information about the steering wheel's neutral position is stored in the controller. This information can be erased when the battery is removed from the vehicle, such as during battery replacement. In such cases, it is necessary to restore this information to the controller after the battery replacement is complete.

[0005] The invention allows a neutral position of the steering wheel to be obtained.

[0006] One aspect of the present invention provides a steering device, comprising: a steering shaft configured to rotate in conjunction with operation of a steering wheel, the steering shaft being separate from the steering wheels of a vehicle in terms of power transmission; a motor configured to generate a steering reaction force, which is a torque applied to the steering shaft in a direction opposite to the steering direction; a stop mechanism configured to limit rotation of the steering wheel; and a controller configured to control the power supply to the motor. The controller is configured to execute a first process and a second process when a certain condition is met. The first process includes operating the steering wheel to a first operation end point and then reversing the operation to a second operation end point by controlling the motor. The second process includes calculating a neutral position of the steering wheel based on the rotation angle of the motor at the time when the reverse operation of the steering wheel begins and at the time when the reverse operation of the steering wheel ends.

[0007] With the above configuration, the neutral position of the steering wheel can be obtained when a certain condition is met.

[0008] In the above steering device, the determined condition may include: transitioning from a state where vehicle power is lost to a state where vehicle power is supplied; and a power switch of the vehicle being switched from off to on for the first time after vehicle power is supplied.

[0009] With the above configuration, the neutral position of the steering wheel can be obtained before the operation of the vehicle starts in the case of shifting from a state where the vehicle power supply is lost to a state where the vehicle power supply is supplied.

[0010] In the steering device described above, the controller may be configured to set a target steering angle, which is a target value of the steering wheel steering angle, to an angle equal to or greater than an operating range limit of the steering wheel determined by the detent mechanism for a predetermined time when executing the first process, and to control the motor so that a steering angle calculated based on the rotation angle of the motor follows the target steering angle. The predetermined time may be a time when the steering wheel is operated to a first operation end point and a time when the steering wheel is reversely operated from the first operation end point to a second operation end point.

[0011] With the above configuration, when the first process is executed, the steering wheel can be operated more reliably to the first operation end point and the second operation end point.

[0012] In the above-described steering device, the controller may be configured to instruct the start of execution of the first process through the in-vehicle notification device before the start of execution of the first process when the determined condition is satisfied.

[0013] With the above configuration, the driver is notified of the start of the first process before the first process is started. Therefore, even if the steering wheel rotates due to the execution of the first process, the driver's discomfort can be reduced.

[0014] With the above configuration, a neutral position of the steering wheel can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0016] Figure 1 illustrates a configuration of a steering device according to an embodiment;

[0017] Figure 2 is a rear view of a steering wheel according to an embodiment;

[0018] Figure 3 is a flowchart illustrating a procedure of a steering wheel reference point detection process according to an embodiment;

[0019] Figure 4A is a rear view illustrating a rotational position of a steering wheel during execution of a steering wheel reference point detection process according to an embodiment;

[0020] Figure 4B is a rear view illustrating a rotational position of a steering wheel during execution of a steering wheel reference point detection process according to an embodiment; and

[0021] Figure 4C is a rear view illustrating a rotational position of a steering wheel during execution of a steering wheel reference point detection process according to an embodiment. DETAILED DESCRIPTION

[0022] The steering device according to the embodiment will be described below. Figure 1 As shown, the vehicle steering system 10 includes a reaction force unit 20 that applies a steering reaction force to the vehicle's steering wheel 11, and a steering unit 30 that steers the vehicle's steering wheels 12, 12. The steering reaction force refers to a torque that acts in a direction opposite to the direction of the driver's operation of the steering wheel 11. Applying the steering reaction force to the steering wheel 11 allows for a suitable response to the driver.

[0023] The reaction force unit 20 includes a steering shaft 21 coupled to the steering wheel 11 , a reaction force motor 22 , a speed reduction mechanism 23 , a rotation angle sensor 24 , a torque sensor 25 , and a reaction force control unit 27 .

[0024] The reaction motor 22 is a source of steering reaction force. For example, the reaction motor 22 may be a three-phase brushless motor. The reaction motor 22 is coupled to the steering shaft 21 via a speed reduction mechanism 23. The torque generated by the reaction motor 22 is applied to the steering shaft 21 as a steering reaction force.

[0025] The reaction force motor 22 is provided with a rotation angle sensor 24. The rotation angle sensor 24 detects the rotation angle θ of the reaction force motor 22. a The torque sensor 25 is provided on a portion of the steering shaft 21 between the speed reduction mechanism 23 and the steering wheel 11. The torque sensor 25 senses the steering torque T applied to the steering shaft 21 by rotating the steering wheel 11. h Conduct testing.

[0026] The reaction force control unit 27 determines the rotation angle θ of the reaction force motor 22 based on the rotation angle θ detected by the rotation angle sensor 24. a To calculate the steering angle θ s , the steering angle θ s is the rotation angle of the steering shaft 21. The reaction force control unit 27 refers to the rotation angle θ of the reaction force motor 22 corresponding to the steering neutral position of the steering wheel 11. a The reaction force control unit 27 calculates the steering angle θ of the steering wheel 11 in the following manner. s : Calculates the integral angle by using the motor midpoint as the origin for the rotation angle θ a The angle obtained by integration is calculated and the calculated integrated angle is multiplied by a conversion coefficient based on the rotation speed ratio of the speed reduction mechanism 23. The motor midpoint is stored in the reaction force control unit 27 as steering angle midpoint information.

[0027] When the power switch of the vehicle is turned off, the reaction force control unit 27 stores the steering angle θ immediately before that. s In addition, the reaction force control unit 27 detects the rotation amount (number of revolutions) of the reaction force motor 22 when the battery is connected during the period when the power switch of the vehicle is off. When the switched power source is switched from off to on, the reaction force control unit 27 uses the rotation amount of the reaction force motor 22 detected during the period when the power switch is off to calculate the steering angle θ immediately before the power supply to the reaction force control unit 27 is blocked. s Correction is performed to calculate the correct steering angle θ s .

[0028] The reaction force control unit 27 performs reaction force control to generate a steering torque T h The reaction force control unit 27 is based on the steering torque T detected by the torque sensor 25. h To calculate the target steering reaction force, and based on the calculated target steering reaction force and steering torque T hThe target steering angle of the steering wheel 11 is calculated. The reaction force control unit 27 calculates the rotation angle θ based on the reaction force motor 22. a The calculated steering angle θ s The reaction force control unit 27 uses the rotation angle θ of the reaction force motor 22 detected by the rotation angle sensor 24 to determine the difference between the reaction force motor 22 and the target steering angle, and controls the power supply to the reaction force motor 22 to eliminate the difference. a The reaction force motor 22 is vector controlled.

[0029] The steering unit 30 includes a steered shaft 31, a steering motor 32, a speed reduction mechanism 33, a pinion shaft 34, a rotation angle sensor 35, and a steering control unit 36. The steered shaft 31 extends in the vehicle-width direction ( Figure 1 The right and left steering wheels 12 and 12 are connected to both ends of the steered shaft 31 via corresponding tie rods 13 and 13.

[0030] The steering motor 32 is a source of steering force. For example, the steering motor 32 may be a three-phase brushless motor. The steering motor 32 is coupled to a pinion shaft 34 via a reduction gear mechanism 33. The pinion teeth 34a of the pinion shaft 34 mesh with the rack teeth 31a of the steered shaft 31. The torque generated by the steering motor 32 is applied to the steered shaft 31 as steering force via the pinion shaft 34. The steered shaft 31 is rotated in the vehicle-width direction ( Figure 1 The steering angle θ of the steering wheels 12, 12 is w It changes with the movement of the steered shaft 31 .

[0031] The rotation angle sensor 35 is provided to the steering motor 32. The rotation angle sensor 35 detects the rotation angle θ of the steering motor 32. b The steering control unit 36 performs steering control to steer the steerable wheels 12, 12 according to the steering state by driving control of the steering motor 32. The steering control unit 36 is based on the rotation angle θ of the steering motor 32 detected by the rotation angle sensor 35. b To calculate the rotation angle θ of the pinion shaft 34 p In addition, the steering control unit 36 calculates the target rotation angle of the pinion shaft 34 using the target steering angle calculated by the reaction force control unit 27. The target rotation angle of the pinion shaft 34 is calculated based on the viewpoint of achieving a predetermined steering angle ratio. The steering control unit 36 calculates the target rotation angle of the pinion shaft 34 and the actual rotation angle θ p The steering control unit 36 uses the rotation angle θ of the steering motor 32 detected by the rotation angle sensor 35 to determine the difference between the two and controls the power supply to the steering motor 32 to eliminate the difference.b The steering motor 32 is vector controlled.

[0032] Stop mechanism

[0033] like Figure 2 As shown, the reaction force unit 20 has a stopper mechanism 40. The stopper mechanism 40 provides a control for the steering angle θ of the steering wheel 11. s The stop mechanism 40 limits the rotation of the steering wheel 11 to more than one circle (360°). Figure 2 The steering wheel 11 is illustrated when viewed from the rear side.

[0034] The stopper mechanism 40 has a first limiting member 41 and a second limiting member 42. The first limiting member 41 is fixed to a steering column 43 that supports the steering shaft 21 on the vehicle body. The first limiting member 41 extends in the radial direction of the steering shaft 21. The first limiting member 41 has a first limiting surface 41a and a second limiting surface 41b positioned on opposite sides of each other in the rotation direction of the steering shaft 21. The first limiting surface 41a and the second limiting surface 41b are inclined so as to approach each other toward the steering shaft 21 in the radial direction of the steering shaft 21. The first limiting member 41 is provided with respect to the neutral position (steering angle θ) of the steering wheel 11. s =0°).

[0035] The second restricting member 42 is fixed to the outer peripheral surface of the steering shaft 21. The second restricting member 42 is positioned near the end portion of the steering shaft 21 on the steering wheel 11 side. The second restricting member 42 extends in a direction orthogonal to the central rotation axis of the steering shaft 21. The second restricting member 42 can abut against the first restricting member 41 in the rotational direction of the steering shaft 21. Therefore, the steering wheel 11 moves between a first restricting position in which the second restricting member 42 abuts against the first restricting surface 41a of the first restricting member 41 and a second restricting position in which the second restricting member 42 abuts against the second restricting surface 41b of the first restricting member 41.

[0036] For example, when the angle between the first restriction surface 41a and the second restriction surface 41b is set to 20°, when the steering wheel 11 is turned in the left steering direction ( Figure 2 At the moment when the steering wheel 11 is rotated 170° in the clockwise direction (in the right direction), the second restricting member 42 abuts against the first restricting surface 41a of the first restricting member 41. Figure 2 At the moment of rotation 170° (counterclockwise in FIG), the second restricting member 42 abuts against the second restricting surface 41b of the first restricting member 41. That is, the operating range of the steering wheel 11 is restricted to within a range of ±170° about the neutral position of the steering wheel 11, or a total of 340°.

[0037] The positional relationship between the steering wheel 11 and the steering wheels 12, 12 is maintained to match the determined steering angle ratio. For example, when the steering wheel 11 is operated throughout its entire operating range, the steering wheels 12, 12 are also steered throughout their entire steering range. Here, the operating range of the steering wheel 11 is limited to less than 360°, and therefore, the steering wheels 12, 12 can be steered throughout their entire steering range without having to rotate the steering wheel 11 completely. In other words, there is no need to change the gripping force on the steering wheel 11.

[0038] Here, for example, when the battery is removed from the vehicle during battery replacement work, power is not supplied to the reaction force control unit 27. Therefore, the steering angle midpoint information stored in the reaction force control unit 27 is lost. Therefore, the reaction force control unit 27 resets the steering angle midpoint information when the power switch is turned on for the first time after the new battery is attached.

[0039] Next, we will refer to Figure 3 The flowchart in FIG. 1 describes the steering angle midpoint setting process performed by the reaction force control unit 27. The process in the flowchart begins when certain execution start conditions are met. These include: a transition from a state in which vehicle power is lost to a state in which vehicle power is supplied, such as when battery replacement is complete; and the first switching of the power switch from off to on after vehicle power is supplied.

[0040] When the steering wheel 11 is rotated in the left steering direction about the neutral position, the steering angle θ s is a negative value, and when the steering wheel 11 rotates in the right steering direction, the steering angle θ s The operating range of the steering wheel 11 is limited by the stopper mechanism 40 to within a range of ±170° about the neutral position.

[0041] like Figure 3 As indicated in the flowchart of FIG, the reaction force control unit 27 sets a first target steering angle θ s1 * The reaction force control unit 27 rotates the steering wheel 11 to the left based on the rotation angle θ of the reaction force motor 22 when the power switch is turned on. a Calculate the current steering angle θ as the initial position of the steering wheel 11 s , and the steering angle θ calculated from s The value obtained by subtracting 360° corresponding to one rotation of the steering wheel 11 from the first target steering angle θ is set as the first target steering angle θ. s1 * In addition, the reaction force control unit 27 sets the steering angle θ as the initial position of the steering wheel 11s The value is temporarily stored.

[0042] For example, when the steering angle θ is the initial position s When the value is "-10°", the first target steering angle θ s1 * is "-370°." In step S101, regardless of the initial position of the steering wheel 11, the angle to be subtracted from the initial position of the steering wheel 11 is set from the viewpoint of causing the movable second restricting member 42 to reach the fixed first restricting member 41. For example, the second restricting member 42 may be caused to move from the second restricting position P2 where the second restricting member 42 abuts the second restricting surface 41b to the first restricting position P1 where the second restricting member 42 abuts the first restricting surface 41a of the first restricting member 41. Therefore, the angle to be subtracted from the initial position of the steering wheel 11 may not be 360°, and may be an angle equal to or greater than the operating range of the steering wheel 11 determined by the stop mechanism 40.

[0043] Next, the reaction force control unit 27 calculates the steering angle θ s Feedback control is performed so that the steering angle θ s Follow the first target steering angle θ s1 * (Step S102 ) The reaction force control unit 27 determines whether the second restricting member 42 rotating together with the steering wheel 11 has reached the first restricting position P1 where the second restricting member 42 abuts against the first restricting surface 41 a of the first restricting member 41 (Step S103 ).

[0044] When all four conditions A1 to A4 are satisfied, the reaction force control unit 27 determines that the second restricting member 42 has reached the first restricting position P1 .

[0045] I a ≥I th ···(A1)

[0046] “I a "I is the absolute value of the current supplied to the reaction force motor 22. th " is the current threshold. The current threshold I th The setting is based on the viewpoint that an increase in the current of the reaction force motor 22 accompanying an increase in the load on the reaction force motor 22 is detected after the second restricting member 42 reaches the first restricting position P1 .

[0047] T h ≤T th ···(A2)

[0048] “T h " is the steering torque. "T th” is a torque threshold value, which is set based on the viewpoint of detecting a state in which the steering wheel 11 is not operated by the driver.

[0049] ω≤ω th ···(A3)

[0050] “ω” is the steering angular velocity. th ” is an angular velocity threshold value, which is set based on the viewpoint of detecting a state in which the steering wheel 11 is not operated by the driver.

[0051] t≥t th ···(A4)

[0052] “t” is the time when the three conditions A1 to A3 are met. th ” is a time threshold value that is set based on the viewpoint of preventing erroneous determination that the second restricting member 42 has reached the first restricting position P1 when, for example, the three conditions A1 to A3 are instantaneously satisfied.

[0053] When it is determined that the second restricting member 42 has not yet reached the first restricting position P1 ("No" in step S103), the reaction force control unit 27 proceeds to the processing in the above-mentioned step S102. When it is determined that the second restricting member 42 has reached the first restricting position P1 ("Yes" in step S103), the reaction force control unit 27 sets the steering angle θ at this time to s The amount of increase or decrease (or the initial position and the steering angle θ s The difference between the two) is temporarily stored as the first end angle θ end1 (Step S104).

[0054] like Figure 4A As shown in the figure, for example, when the steering angle θ is the initial position s When the value is "-10°", the first end angle θ end1 is "-160°". This is because the operating range of the steering wheel 11 is limited by the stop mechanism 40 to the neutral position (θ s At this time, the steering wheel 11 rotates to a position reaching "-170°" from "-10°" as the starting point (i.e., 0°), and therefore, the reaction force control unit 27 recognizes the position where the rotation of the steering wheel 11 is restricted by the stopper mechanism 40 as "-160°".

[0055] Next, the reaction force control unit 27 sets the second target steering angle θ s2 *The reaction force control unit 27 compares 360° corresponding to one rotation of the steering wheel 11 with the steering angle θ stored as the initial position of the steering wheel 11. s The value obtained by adding is set as the second target steering angle θ s2 * .

[0056] For example, when the steering angle θ is the initial position s When the value is "-10°", the second target steering angle θ s2 * is "350°." Just like the angle to be subtracted from the initial position of the steering wheel 11 in step S101 described above, the angle to be added to the initial position of the steering wheel 11 in step S105 may not be 360°, and may be an angle equal to or greater than the operating range of the steering wheel 11 determined by the detent mechanism 40.

[0057] Next, the reaction force control unit 27 calculates the steering angle θ s Feedback control is performed so that the steering angle θ s Follow the second target steering angle θ s2 * (Step S106 ) Next, the reaction force control unit 27 determines whether the second restricting member 42 rotating together with the steering wheel 11 has reached the second restricting position P2 where the second restricting member 42 abuts against the second restricting surface 41 b of the first restricting member 41 (Step S107 ).

[0058] When it is determined that the second restricting member 42 has not yet reached the second restricting position P2 ("No" in step S107), the reaction force control unit 27 proceeds to the processing in the above-mentioned step S106. When it is determined that the second restricting member 42 has reached the second restricting position P2 ("Yes" in step S107), the reaction force control unit 27 sets the steering angle θ at this time to s The amount of increase or decrease (or the initial position and the steering angle θ s The difference between the two) is temporarily stored as the second end angle θ end2 (Step S108).

[0059] like Figure 4B As shown in the figure, for example, when the steering angle θ is the initial position s When the value is "-10°", the second end angle θ end2At this time, the steering wheel 11 rotates from -170° to -10°, and thus, from -10°, which is the starting point (i.e., 0°), to the position where it reaches 170°. Therefore, the reaction force control unit 27 recognizes the position where the rotation of the steering wheel 11 is restricted by the stopper mechanism 40 as 180°, which is the actual rotation amount of the steering wheel 11.

[0060] Next, the reaction force control unit 27 calculates the reaction force based on the first end angle θ stored in the above steps S104 and S108. end1 and the second termination angle θ end2 Calculate the steering angle θ s The midpoint θ s0 (Step S109) The reaction force control unit 27 calculates the first end angle θ end1 and the second termination angle θ end2 The value of half of the sum is taken as the steering angle θ s The midpoint θ s0 , as indicated by formula (B) below.

[0061] θ s0 =(θ end1 +θ end2 ) / 2···(B)

[0062] For example, when the steering angle θ is the initial position s When the value is "-10°", the first end angle θ end1 is "-160°", and the second end angle θ end2 is "180°". Therefore, the steering angle θ s The midpoint θ s0 The value of is "10°". The calculated steering angle θ s The midpoint θ s0 The motor midpoint corresponds to the rotation angle θ of the reaction motor 22 corresponding to the steering neutral position of the steering wheel 11. a .

[0063] The reaction force control unit 27 converts the steering angle θ calculated in step S109 into s The midpoint θ s0 and the steering angle θ s The midpoint θ s0 The corresponding motor midpoint is stored as steering angle midpoint information (step S110 ).

[0064] Next, the reaction force control unit 27 calculates the third target steering angle θ s3 * In order to move the steering wheel 11 to the steering angle θ s The midpoint θs0 The reaction force control unit 27 stores the steering angle θ stored in the above step S110. s The midpoint θ s0 The value of is set as the third target steering angle θ s3 * .

[0065] Next, the reaction force control unit 27 calculates the steering angle θ s Feedback control is performed so that the steering angle θ s Follow the third target steering angle θ s3 * (Step S112) Next, the reaction force control unit 27 determines the steering angle θ s Is it consistent with the third target steering angle θ s3 * When the steering angle θ is determined s and the third target steering angle θ s3 * When the steering angle θ is not consistent (No in step S113), the reaction force control unit 27 proceeds to the process in the above-mentioned step S112. s and the third target steering angle θ s3 * If they agree (YES in step S113 ), the reaction force control unit 27 terminates the process.

[0066] like Figure 4C As shown in the figure, the rotation position of the steering wheel 11 reaches the steering angle θ s The true midpoint θ s0 As described above, the steering angle midpoint setting process is completed.

[0067] After the setting of the steering angle midpoint is completed, the reaction force control unit 27 controls the steering angle θ of the steering wheel 12. w Synchronous control is performed. Synchronous control is a control for matching the rotational position of the steering wheel 11 with the steering position of the steering wheel 12. The reaction force control unit 27 obtains the rotation angle θ of the pinion shaft 34 through the steering control unit 36. p , and the reaction force motor 22 is operated so that the steering angle θ of the steering wheel 11 s The rotation angle θ of the pinion shaft 34 that matches the predetermined steering angle ratio is reached. p , that is, the steering angle θ of the steering wheel 12 w Since the positional relationship between the steering wheel 11 and the steered wheels 12 is maintained to match the predetermined steering angle ratio, the driver can steer the steering wheel 11 without feeling uncomfortable.

[0068] Effects of implementation methods

[0069] Therefore, the following effects can be obtained by this embodiment. When the determined condition is met, the reaction force control unit 27 controls the reaction force motor 22 to operate the steering wheel 11 to the first operation end point (the angle θ with respect to the first end point) end1 The corresponding position), and then reverse operation to the second operation end point (with the second end angle θ end2 Then, the neutral position of the steering wheel 11, that is, the steering angle θ s The midpoint θ s0 ——Based on the first end angle θ end1 and the second termination angle θ end2 Calculate the first end angle θ end1 is the rotation angle of the reaction force motor 22 at the start of the reverse operation, and the second end angle θ end2 is the rotation angle of the reaction force motor 22 when the reverse operation is terminated. Therefore, when the determined condition is established, the neutral position of the steering wheel 11 can be obtained.

[0070] The conditions to be determined include: a transition from a state where vehicle power is lost to a state where vehicle power is supplied; and the first time the vehicle power switch is switched from off to on after vehicle power is supplied. Therefore, in the event of a transition from a state where vehicle power is lost to a state where vehicle power is supplied, the neutral position of the steering wheel 11 can be achieved before the vehicle begins operating.

[0071] When the steering wheel 11 is operated to the first operation end point, and when the steering wheel 11 is reversely operated from the first operation end point to the second operation end point, the reaction force control unit 27 sets the target steering angle (θ s1 * ,θ s2 * ) is set to an angle equal to or greater than the limit value (here, ±170°) of the operating range of the steering wheel 11 determined by the stopper mechanism 40. Then, the reaction force control unit 27 controls the reaction force motor 22 so that the reaction force motor 22 rotates at a rotation angle θ of the reaction force motor 22. a The calculated steering angle θ s Follow the target steering angle (θ s1 * ,θ s2 * ). Therefore, the steering wheel 11 can be operated to the first operation end point and the second operation end point more reliably.

[0072] In a so-called steer-by-wire steering system 10, in which the steering wheel 11 and the steered wheels 12, 12 are separated in terms of power transmission, the neutral position of the steering wheel 11 is calculated by operating the reaction force unit 20. Therefore, the entire vehicle system, including the steered wheels 12, 12, does not need to be operated during the steering angle midpoint setting process, unlike an electric power steering (EPS) system in which the steering wheel 11 and the steered wheels 12, 12 are not separated in terms of power transmission. Therefore, the neutral position of the steering wheel 11 can be calculated by generating a smaller motor torque.

[0073] Other implementations

[0074] This embodiment can be modified as follows. In this embodiment, the rotation angle θ of the reaction force motor 22 is used. a The calculated steering angle θ s However, when the steering device 10 is configured to have a steering angle sensor, the steering angle θ detected by the steering angle sensor may also be used. s .

[0075] In this embodiment, the steering angle ratio is set to an appropriate value according to product specifications, etc. The steering angle ratio can be, for example, "θ s :θ w =1:1", or it can be "θ s :θ w =1:3". For example, when Figure 1 If the notification device 28 indicated by the double-dashed line in the figure is installed in the passenger compartment, the reaction force control unit 27 can use the notification device 28 to indicate the execution status of the steering angle midpoint setting process. For example, when the conditions for starting the steering angle midpoint setting process are met, the reaction force control unit 27 can use the notification device 28 to indicate the start of the steering angle midpoint setting process and then begin executing the steering angle midpoint setting process. Alternatively, the reaction force control unit 27 can use the notification device 28 to indicate that the steering angle midpoint setting process is in progress from the start of the steering angle midpoint setting process until its completion. Furthermore, the reaction force control unit 27 can use the notification device 28 to indicate the completion of the steering angle midpoint setting process upon completion. Examples of notification operations performed by the notification device 28 include displaying a text message and issuing a voice message. In this way, even if the steering wheel 11 rotates independently of the driver's steering operation at the start of the steering angle midpoint setting process, the driver is visually or audibly notified by the notification device 28 that the steering wheel 11 has rotated due to the execution of the steering angle midpoint setting process. This can reduce any discomfort experienced by the driver.

[0076] In the present embodiment, the steering wheel 11 is rotated to the left and then to the right in the steering angle midpoint setting process. However, the steering wheel 11 may be rotated to the right and then to the left.

[0077] When the steering wheel 11 is rotated by executing the steering angle midpoint setting process, the reaction force control unit 27 can maintain a certain amount of rotation per unit time of the steering wheel 11. In this way, sudden rotation of the steering wheel 11 is suppressed, and thus the discomfort given to the driver can be reduced.

[0078] In this embodiment, the operating range of the steering wheel 11 is always limited to less than one rotation by the stopper mechanism 40. However, the stopper mechanism 40 may be activated only when the steering angle midpoint setting process is being executed. In this case, for example, the first stopper member 41 is provided so as to be movable relative to the steering column 43. Furthermore, the first stopper member 41 is provided so as to be movable between an engaged position within the rotational trajectory of the second stopper member 42 and a retracted position outside the rotational trajectory of the second stopper member 42.

[0079] In this embodiment, the steering angle midpoint setting process is executed when the power switch is turned on for the first time after battery replacement. However, for example, the steering angle midpoint setting process may be executed each time the power switch is turned on, regardless of whether the battery replacement work is performed.

[0080] In this embodiment, the steering angle θ corresponding to the neutral position of the steering wheel 11 is s The midpoint θ s0 is used as a reference point for the operation of the reaction force unit 20. However, the steering angle θ corresponding to the position away from the neutral position of the steering wheel 11 s can be used as a reference point for the operation of the reaction force unit 20 as long as the position can be aligned with the steered angle θ of the steered wheel 12. w Just be relevant.

[0081] In this embodiment, the reaction force control unit 27 and the steering control unit 36 can be configured as a single controller. In this embodiment, a so-called uncoupled structure is used for the vehicle steering device 10, in which the steering shaft 21 and the steering wheels 12 are separated in terms of power transmission. However, a structure in which the steering shaft 21 and the steering wheels 12 can be separated in terms of power transmission using a clutch can also be adopted. When the clutch is disengaged, power transmission between the steering wheel 11 and the steering wheels 12 is blocked. When the clutch is engaged, power transmission between the steering wheel 11 and the steering wheels 12 is allowed.

[0082] Other technical ideas

[0083] Next, the technical concepts learned from this embodiment are further described below. When the steering wheel rotates through the execution of the first and second processes, the controller maintains the steering wheel's rotation amount per unit time at a constant level. This suppresses sudden steering wheel rotation, thereby reducing driver discomfort.

Claims

1. A steering device (10), characterized in that: The steering device (10) comprises: a steering shaft (21) configured to rotate along with the operation of the steering wheel (11), the steering shaft (21) being separated from the steering wheel (12) of the vehicle in terms of power transmission; a motor (22) configured to generate a steering reaction force, the steering reaction force being a torque applied to the steering shaft (21) in a direction opposite to the steering direction; a stop mechanism (40) configured to limit rotation of the steering wheel (11); and a controller (27) configured to control the supply of power to the motor (22), wherein The controller (27) is configured to execute the first process and the second process when a determined condition is satisfied, The first process includes: operating the steering wheel (11) to a first operation end point and then operating it in reverse to a second operation end point by controlling the motor (22), and The second processing includes calculating a neutral position of the steering wheel (11) based on a rotation angle of the motor at a time point when the reverse operation of the steering wheel (11) starts and a time point when the reverse operation of the steering wheel (11) ends, The controller (27) further performs the following processing: when an operation end point arrival condition is satisfied during the execution of the first processing or the second processing, it is determined that the first operation end point or the second operation end point has been reached, The operation end point arrival condition includes: a current condition, which indicates that the absolute value of the current supplied to the motor (22) is greater than a current threshold; a torque condition, which indicates that the steering torque applied to the steering shaft (21) by the rotation operation of the steering wheel (11) is less than a torque threshold; an angular velocity condition, which indicates that the steering angular velocity is less than an angular velocity threshold; and a time condition, which indicates that the time for which the three conditions of the current condition, the torque condition, and the angular velocity condition are met is greater than a time threshold. The current threshold is set based on the viewpoint that an increase in the current of the motor (22) accompanying an increase in the load on the motor (22) is detected after the steering wheel (11) reaches the first operation end point or the second operation end point, The torque threshold is set based on the viewpoint of detecting a state in which the steering wheel (11) is not operated by the driver. The angular velocity threshold is set based on the viewpoint of detecting a state in which the steering wheel (11) is not operated by the driver. The time threshold is set based on the viewpoint of preventing the steering wheel (11) from being mistakenly determined to have reached the first operation end point or the second operation end point when the three conditions of the current condition, the torque condition, and the angular velocity condition are instantaneously satisfied. When the current condition, the torque condition, the angular velocity condition, and the time condition are all satisfied, the operation end point arrival condition is satisfied.

2. The steering device (10) according to claim 1, characterized in that The determined conditions include: a transition from a state where vehicle power is lost to a state where the vehicle power is supplied; and a power switch of the vehicle being switched from off to on for the first time after the vehicle power is supplied.

3. The steering device (10) according to claim 1 or 2, characterized in that The controller (27) is configured to set a target steering angle, which is a target value of the steering angle of the steering wheel (11), to an angle equal to or greater than an operating range limit value of the steering wheel (11) determined by the stop mechanism (40) within a predetermined time when the first processing is performed, and the controller (27) is configured to control the motor (22) so that the steering angle calculated based on the rotation angle of the motor (22) follows the target steering angle, the predetermined time being the time when the steering wheel (11) is operated to the first operating end point and the time when the steering wheel (11) is reversely operated from the first operating end point to the second operating end point.

4. The steering device (10) according to claim 1 or 2, characterized in that The controller (27) is configured to instruct the start of execution of the first process through an in-vehicle notification device before the start of execution of the first process when the determined condition is satisfied.

Images