Method for determining a steering angle, and control device

Abstract

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

Description

[0001] This application is a divisional application of the parent application with the applicant of "ZETTA GEAR CO., LTD.", the title of "Steering device", the filing date of "June 11, 2021", and the application number of "202110656609.4". TECHNICAL FIELD

[0002] The present application relates to a method for determining a steering angle, and a controller. BACKGROUND

[0003] A so-called steer-by-wire type steering device is provided in which a steering wheel and a steered 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 that includes a reaction force mechanism having a reaction force motor that serves as a source of generation of a steering reaction force to be applied to a steering shaft, and a steering mechanism having a steering motor that serves as a source of generation of a steering force for steering a steered wheel. When a vehicle is running, a controller for the steering device controls generation of the steering reaction force by power supply to the reaction force motor, and controls steering of the steered wheel by power supply to the steering motor. SUMMARY

[0004] In the steering device according to JP 2013-252804 A, the steering motor is controlled based on a steering angle of the steering wheel. The steering device also has a stopper member for providing a limit to the steering angle of the steering wheel. Therefore, in order to maintain a positional relationship between the steering wheel and the steered wheel to match a predetermined steering angle ratio, the steering wheel and the steered wheel must be operated with the neutral position of the steering wheel and the neutral position of the steered wheel coinciding with each other.

[0005] For example, when the steering device is assembled, steering angle midpoint information corresponding to the neutral position of the steering wheel is stored in the controller. For example, in the case where a battery is removed from the vehicle when a battery replacement work is performed, the steering angle midpoint information stored in the controller is sometimes erased. In this case, after the battery replacement work is completed, it is necessary to store the steering angle midpoint information in the controller again.

[0006] The present application allows the neutral position of the steering wheel to be obtained.

[0007] An aspect of the present application provides a steering device including: a steering shaft configured to rotate together with operation of a steering wheel, the steering shaft being separate from a steered wheel of a vehicle in terms of power transmission; a motor configured to generate a steering reaction force that is a torque applied to the steering shaft in a direction opposite to a steering direction; a stop mechanism configured to limit rotation of the steering wheel; and a controller configured to control supply of electric power to the motor. The controller is configured to execute first processing and second processing when a determined condition is established. The first processing includes causing the steering wheel to be operated to a first operation end point and thereafter reversely operated to a second operation end point by control of the motor. The second processing includes calculating a neutral position of the steering wheel based on a rotation angle of the motor at a time point when the reverse operation of the steering wheel is started and at a time point when the reverse operation of the steering wheel is terminated.

[0008] With the above configuration, the neutral position of the steering wheel can be obtained when the determined condition is established.

[0009] In the above steering device, the determined condition can include: transition from a state where power of the vehicle is lost to a state where power of the vehicle is supplied; and first switching of a power switch of the vehicle from off to on after the power of the vehicle is supplied.

[0010] With the above configuration, the neutral position of the steering wheel can be obtained before operation of the vehicle is started in a case where the state where the power of the vehicle is lost is transitioned to the state where the power of the vehicle is supplied.

[0011] In the above steering device, the controller can be configured to set a target steering angle that is a target value of a steering angle of the steering wheel to an angle equal to or greater than an operation range limit value of the steering wheel determined by the stop mechanism for a predetermined time when the first processing is executed, and the controller can be configured to control the motor so that a steering angle calculated based on a rotation angle of the motor follows the target steering angle. The predetermined time can be a time when the steering wheel is operated to the first operation end point and a time when the steering wheel is reversely operated to the second operation end point from the first operation end point.

[0012] With the above configuration, the steering wheel can be more reliably operated to the first operation end point and the second operation end point when the first processing is executed.

[0013] In the above steering device, the controller can be configured to indicate start of execution of the first processing by an in-vehicle notification device before start of execution of the first processing when the determined condition is established.

[0014] With the above configuration, the driver is notified of the start of execution of the first processing before the start of execution of the first processing. Therefore, even if the steering wheel is rotated by the execution of the first processing, discomfort given to the driver can be reduced.

[0015] By the above configuration, the neutral position of the steering wheel can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0016] Features, advantages, and technical and industrial significance of exemplary embodiments of the application will be described below with reference to the accompanying drawings, wherein the same reference numerals in different drawings denote the same element, and wherein:

[0017] Figure 1 illustrates a configuration of a steering apparatus according to an embodiment;

[0018] Figure 2 is a rear view of a steering wheel according to an embodiment;

[0019] Figure 3 is a flowchart illustrating a procedure of a steering wheel reference point detection process according to an embodiment;

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

[0021] Figure 4B is a rear view of a steering wheel illustrating a rotational position of the steering wheel during execution of a steering wheel reference point detection process according to an embodiment; and

[0022] Figure 4C is a rear view of a steering wheel illustrating a rotational position of the steering wheel during execution of a steering wheel reference point detection process according to an embodiment. DETAILED DESCRIPTION

[0023] A steering apparatus according to an embodiment will be described below. As Figure 1 illustrated, a steering apparatus 10 of a vehicle has a reaction force unit 20 that applies a steering reaction force to a steering wheel 11 of the vehicle, and a steering unit 30 that steers steered wheels 12, 12 of the vehicle. The steering reaction force refers to a torque that acts in a direction opposite to an operation direction of the steering wheel 11 performed by a driver. A driver can be given a moderate response by applying the steering reaction force to the steering wheel 11.

[0024] The reaction force unit 20 has a steering shaft 21 coupled to the steering wheel 11, a reaction force motor 22, a reduction mechanism 23, a rotation angle sensor 24, a torque sensor 25, and a reaction force control unit 27.

[0025] The reaction force motor 22 is a source of generation of the steering reaction force. For example, the reaction force motor 22 can be a three-phase brushless motor. The reaction force motor 22 is coupled to the steering shaft 21 via the reduction mechanism 23. A torque generated by the reaction force motor 22 is applied to the steering shaft 21 as the steering reaction force.

[0026] A rotation angle sensor 24 is provided to the reaction force motor 22. The rotation angle sensor 24 detects a rotation angle θ a of the reaction force motor 22. h A torque sensor 25 is provided to a portion of the steering shaft 21 between the reduction mechanism 23 and the steering wheel 11. The torque sensor 25 detects a steering torque T a applied to the steering shaft 21 by an operation of rotating the steering wheel 11.

[0027] A reaction force control unit 27 calculates a steering angle θ s based on the rotation angle θ s of the reaction force motor 22 detected by the rotation angle sensor 24, which is a rotation angle of the steering shaft 21. The reaction force control unit 27 counts the number of rotations with reference to a rotation angle θ a of the reaction force motor 22 corresponding to a neutral position of the steering wheel 11 (hereinafter referred to as "motor midpoint"). The reaction force control unit 27 calculates a steering angle θ s of the steering wheel 11 in the following manner: calculates an integrated angle that is an angle obtained by integrating the rotation angle θ a using the motor midpoint as an origin, and multiplies the calculated integrated angle by a conversion factor based on a speed ratio of the reduction mechanism 23. The motor midpoint is stored in the reaction force control unit 27 as steering angle midpoint information.

[0028] When the power switch of the vehicle is turned off, the reaction force control unit 27 stores a value of the steering angle θ s immediately before this. In addition, the reaction force control unit 27 detects the amount of rotation (number of rotations) of the reaction force motor 22 when the battery is connected during the period when the power switch of the vehicle is turned off. When the power supply that has been switched from off to on, the reaction force control unit 27 calculates a correct steering angle θ s by correcting the steering angle θ s immediately before the power supply of the reaction force control unit 27 is blocked immediately before this using the amount of rotation of the reaction force motor 22 detected during the period when the power switch is turned off.

[0029] The reaction force control unit 27 performs reaction force control to generate a steering reaction force matching the steering torque T h by drive control of the reaction force motor 22. The reaction force control unit 27 calculates a target steering reaction force based on the steering torque T h detected by the torque sensor 25, and performs the reaction force control based on the calculated target steering reaction force and the 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.

[0030] 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.

[0031] 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 .

[0032] 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.

[0033] Stop mechanism

[0034] 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.

[0035] 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°).

[0036] 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.

[0037] 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°.

[0038] 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 over the entire operation range, the steering wheels 12, 12 are also steered over the entire steering range. Here, the operation range of the steering wheel 11 is limited to a range smaller than 360°, and therefore, the steering wheels 12, 12 can be steered over the entire steering range without rotating the steering wheel 11 by one revolution. That is, it is not necessary to change the grip force on the steering wheel 11.

[0039] Here, for example, when the battery is removed from the vehicle in the battery replacement work, no electric power is 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, when the power switch is turned on for the first time after the new battery is attached, the reaction force control unit 27 sets the steering angle midpoint information again.

[0040] Next, the process of the steering angle midpoint setting processing by the reaction force control unit 27 will be described with reference to the flowchart in Figure 3 When the determined execution start condition is satisfied, the processing in the flowchart starts execution. The execution start condition includes: a state transition from a state in which the electric power of the vehicle is lost to a state in which the electric power of the vehicle is supplied, such as a state when the battery replacement work is completed; and a state in which the power switch is switched from off to on for the first time after the electric power of the vehicle is supplied.

[0041] When the steering wheel 11 is rotated about the neutral position in the left steering direction, the steering angle θ s is a negative value, and when the steering wheel 11 is rotated in the right steering direction, the steering angle θ s is a positive value. The operation range of the steering wheel 11 is limited to a range of ±170° about the neutral position by the stop mechanism 40.

[0042] As indicated in the flowchart of Figure 3 , the reaction force control unit 27 sets the first target steering angle θ s1 * so as to rotate the steering wheel 11 to the left (step S101). The reaction force control unit 27 calculates the current steering angle θ a as the initial position of the steering wheel 11 based on the rotation angle θ s of the reaction force motor 22 at the time when the power switch is turned on, and sets a value obtained by subtracting 360° corresponding to one revolution of the steering wheel 11 from the calculated steering angle θ s as the first target steering angle θ s1 * . In addition, the reaction force control unit 27 sets the steering angle θs The value is temporarily stored.

[0043] 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.

[0044] 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 ).

[0045] 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 .

[0046] I a ≥I th ···(A1)

[0047] “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 .

[0048] T h ≤T th ···(A2)

[0049] “T h " is the steering torque. "T this a torque threshold value that is set based on the viewpoint of detecting a state in which the steering wheel 11 is not operated by the driver.

[0050] ω≤ω th (A3)

[0051] "ω" is a steering angular velocity. "ω th is an angular velocity threshold value that is set based on the viewpoint of detecting a state in which the steering wheel 11 is not operated by the driver.

[0052] t≥t th (A4)

[0053] "t" is a time at which the three conditions Al to A3 are established. "t th is a time threshold value that is set based on the viewpoint of preventing erroneous determination that the second restriction member 42 has reached the first restriction position PI, for example, when the three conditions Al to A3 are momentarily established.

[0054] When it is determined that the second restriction member 42 has not reached the first restriction position PI ("No" in step S103), the reaction force control unit 27 proceeds to the processing in step S102 described above. When it is determined that the second restriction member 42 has reached the first restriction position PI ("Yes" in step S103), the reaction force control unit 27 temporarily stores an amount of increase or decrease in the steering angle θ s (or a difference between the initial position and the steering angle θ s ) at that time as the first termination angle θ end1 (step S104).

[0055] As Figure 4A illustrated, for example, when the value of the steering angle θ s as the initial position is "-10°", the first termination angle θ end1 is "-160°". This is because the operating range of the steering wheel 11 is restricted by the stopper mechanism 40 to a range of ±170° about the neutral position (θ s = 0°) of the steering wheel 11. At this time, the steering wheel 11 is rotated to a position from "-10°" as the starting point (i.e., 0°) to "-170°", and therefore, the reaction force control unit 27 recognizes the position at which the rotation of the steering wheel 11 is restricted by the stopper mechanism 40 as "-160°".

[0056] Next, the reaction force control unit 27 sets the second target steering angle θ s2 *so as to rotate the steering wheel 11 to the right (step S105). The reaction force control unit 27 obtains a value by adding 360° corresponding to one rotation of the steering wheel 11 to the steering angle θ s stored as the initial position of the steering wheel 11 s2 * .

[0057] For example, when the value of the steering angle θ s as the initial position 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 the above step S101, the angle to be added to the initial position of the steering wheel 11 in the step S105 can not be 360°, and can be an angle equal to or greater than the operation range of the steering wheel 11 determined by the stop mechanism 40.

[0058] Next, the reaction force control unit 27 performs feedback control on the steering angle θ s so that the steering angle θ s follows the second target steering angle θ s2 * (step S106). Next, the reaction force control unit 27 determines whether the second restriction member 42 that rotates together with the steering wheel 11 has reached the second limit position P2 at which the second restriction member 42 abuts against the second restriction surface 41b of the first restriction member 41 (step S107).

[0059] When it is determined that the second restriction member 42 has not reached the second limit position P2 (NO in step S107), the reaction force control unit 27 proceeds to the processing in the above step S106. When it is determined that the second restriction member 42 has reached the second limit position P2 (YES in step S107), the reaction force control unit 27 temporarily stores the amount of increase or decrease in the steering angle θ s at this time (or the difference between the initial position and the steering angle θ s ) as the second termination angle θ end2 (step S108).

[0060] As illustrated in Figure 4B , for example, when the value of the steering angle θ s as the initial position is "-10°", the second termination 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.

[0061] 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.

[0062] θ s0 =(θ end1 +θ end2 ) / 2···(B)

[0063] 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 .

[0064] 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 ).

[0065] 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 * .

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Effects of Embodiments

[0070] Thus, the following effects can be obtained by the present embodiment. When the determined condition is satisfied, the reaction force control unit 27 operates the steering wheel 11 to the first operation end point (a position corresponding to the first termination angle θ end1 ) by control of the reaction force motor 22, and thereafter reversely operates to the second operation end point (a position corresponding to the second termination angle θ end2 ). Thereafter, the neutral position of the steering wheel 11, i.e., the midpoint θ s of the steering angle θ s0 , is calculated based on the first termination angle θ end1 and the second termination angle θ end2 . The first termination angle θ end1 is the rotation angle of the reaction force motor 22 at the start of the reverse operation, and the second termination angle θ end2 is the rotation angle of the reaction force motor 22 at the termination of the reverse operation. Thus, when the determined condition is satisfied, the neutral position of the steering wheel 11 can be obtained.

[0071] The determined condition includes: transition from a state in which the vehicle power supply is lost to a state in which the vehicle power supply is provided; and first switching of the power switch of the vehicle from off to on after the vehicle power supply is provided. Thus, the neutral position of the steering wheel 11 can be obtained before the operation of the vehicle starts in the case of transition from a state in which the vehicle power supply is lost to a state in which the vehicle power supply is provided.

[0072] 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 * ) of the steering wheel 11 to an angle equal to or greater than the limit value of the operation range of the steering wheel 11 determined by the stop mechanism 40 (here, ±170°). Then, the reaction force control unit 27 controls the reaction force motor 22 so that the steering angle θ a calculated based on the rotation angle θ s of the reaction force motor 22 follows the target steering angle (θ s1 * , θ s2 * ). Thus, the steering wheel 11 can be more reliably operated to the first operation end point and the second operation end point.

[0073] 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.

[0074] Other implementations

[0075] 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 .

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Other technical ideas

[0084] Next, the technical idea grasped by the present embodiment is described below. When the steering wheel is rotated by execution of the first process and the second process, the controller maintains the amount of rotation of the steering wheel per unit time to a certain amount. In this way, sudden rotation of the steering wheel is suppressed. Discomfort given to the driver can thus be reduced.

Claims

1. A method for determining a steering angle, wherein the steering angle is a rotation angle of a steering wheel in a steer-by-wire steering system of a vehicle, the method comprising: rotating the steering wheel in a first direction or a second direction; detecting a load on a reaction force motor of the steering device while rotating the steering wheel in the first direction or the second direction; when an increase in load on the reaction force motor is detected, temporarily storing a termination angle as the steering angle at which the increase was detected; as well as The steering angle is determined based on the termination angle, wherein: Temporarily storing the end angle is temporarily storing a first end angle when the steering wheel rotates in the first direction and then temporarily storing a second end angle when the steering wheel rotates in the second direction.

2. A method for determining a steering angle, wherein the steering angle is a rotation angle of a steering wheel in a steer-by-wire steering device of a vehicle, the method for determining the steering angle comprising: rotating the steering wheel in a first direction while detecting a load on a reaction force motor of the steering device, thereby rotating the steering wheel in the first direction until an increase in the load on the reaction force motor is detected; when an increase in load on the reaction force motor is detected while the steering wheel is rotating in the first direction, temporarily storing a first end angle as the steering angle at which the increase was detected; rotating the steering wheel in a second direction opposite to the first direction while detecting a load on the reaction force motor, thereby rotating the steering wheel in the second direction until an increase in the load on the reaction force motor is detected; as well as When an increase in load on the reaction force motor is detected while the steering wheel is rotating in the second direction, a second end angle is temporarily stored as the steering angle at which the increase was detected.

3. The method for determining a steering angle according to claim 1 , comprising matching the rotation angle of the steering wheel with a steering position of a steering wheel of the vehicle after determining the steering angle, the steering position being a position corresponding to a steering axis of the steering device.

4. The method for determining a steering angle according to claim 3, characterized in that A rotational position of the steering wheel corresponding to the steering position of the steering wheel is matched with the steering position so that the rotational positions form an angle according to a predetermined steering angle ratio.

5. The method for determining a steering angle according to claim 3, characterized in that The method for determining a steering angle does not include determining the steering angle by temporarily storing a first end angle when the steering wheel is rotated in the first direction and temporarily storing a second end angle when the steering wheel is rotated in the second direction and then steering the steering wheel until the rotational position of the steering wheel matches the steering position of the steering wheel.

6. The method for determining a steering angle according to claim 1, characterized in that Determining the steering angle includes calculating the steering angle based on an angle range obtained from the first and second end angles under the assumption that the first and second end angles are limited to an operating range of the steering wheel.

7. The method for determining a steering angle according to claim 1, characterized in that The steering wheel is rotated in the first direction or the second direction by controlling the reaction force motor.

8. The method for determining a steering angle according to claim 1, characterized in that While the steering wheel is rotated in the first direction or the second direction by controlling the reaction force motor, detection of a load on the reaction force motor is performed by detecting a current supplied to the reaction force motor.

9. The method for determining a steering angle according to claim 1, characterized in that The method includes commencing rotation of the steering wheel in the first direction after being instructed to do so by a notification device.

10. The method for determining a steering angle according to claim 1, characterized in that The rotation range of the steering wheel is within a range limited by a stop mechanism for providing limitation to the steering angle.

11. The method for determining a steering angle according to claim 1, characterized in that The first end angle and the second end angle are detected by a reaction force control unit for controlling the reaction force motor through a sensor that detects a state variable related to the rotation angle of the steering wheel.

12. The method for determining a steering angle of claim 1, comprising determining the steering angle prior to initiating operation of the vehicle.

13. The method for determining a steering angle according to claim 12, comprising: determining that the operation of the vehicle has not begun when a determined condition is met, wherein The condition includes a power switch of the vehicle being switched from off to on.

14. The method for determining a steering angle according to claim 1, comprising detecting a steering torque applied to a steering shaft by an operation of rotating the steering wheel while the steering wheel is rotated in the first direction or the second direction, wherein Temporary storage of the termination angle includes setting as conditions detection of an increase in load on the reaction force motor and detection, based on the steering torque, that the steering wheel is not being operated by the operator.

15. Method for determining a steering angle according to claim 14, characterized in that Detecting an increase in load on the reaction force motor includes comparing the current to a current threshold to determine that the current supplied to the reaction force motor is equal to or greater than the current threshold, and The detecting of the state in which the steering wheel is not operated by the operator includes comparing the steering torque with a torque threshold and obtaining a result that the steering torque is equal to or smaller than the torque threshold.

16. The method for determining a steering angle according to claim 1, comprising: The steering torque applied to the steering shaft by the operation of rotating the steering wheel is detected while the steering wheel is rotated in the first direction or the second direction, wherein Temporary storage of the termination angle includes setting as conditions detection of an increase in load on the reaction force motor, detection of a state in which the steering wheel is not operated by the operator based on the steering torque, and detection of a state in which the steering wheel is not operated by the operator based on a steering angular velocity indicating a change in the steering angle.

17. The method for determining a steering angle according to claim 16, characterized in that Detecting an increase in load on the reaction force motor includes comparing the current to a current threshold to determine that the current supplied to the reaction force motor is equal to or greater than the current threshold, and The detection of the state in which the steering wheel is not operated by the operator includes obtaining a result that the steering torque is equal to or less than the torque threshold by comparing the steering torque and the torque threshold, and obtaining a result that the steering angular velocity is equal to or less than the angular velocity threshold by comparing the steering angular velocity and the angular velocity threshold.

18. A controller for controlling a steer-by-wire steering device of a vehicle, characterized in that: The steering device has a configuration in which a power transmission path between a reaction force unit to which a steering wheel is coupled and a steering unit configured to steer the steering wheel is separated. The reaction force unit includes a reaction force motor that generates torque for rotating the steering wheel. the controller is configured to execute a steering angle determination process of determining a steering angle as a rotation angle of the steering wheel, The steering angle determination process includes: a process of rotating the steering wheel in a first direction or a second direction; a process of detecting a load on the reaction force motor while rotating the steering wheel in the first direction or the second direction; When an increase in load on the reaction force motor is detected, temporarily storing a termination angle as a process of the steering angle at which the increase was detected; and determining the steering angle based on the termination angle, and The process of temporarily storing the end angle is a process of temporarily storing a first end angle when the steering wheel is rotated in the first direction and then temporarily storing a second end angle when the steering wheel is rotated in the second direction.

Images