Parking assistance device

Abstract

To increase the possibility of bringing a steering angle close to a target steering angle.SOLUTION: A parking assist device 100 includes: a driving device 12 that automatically steers steering wheels 16FL, 16FR; and a control unit 50 that controls the driving device. The control unit controls the driving device so that a vehicle 102 moves to a target parking position when receiving a parking assist command. The control unit stores a magnitude θr0 of an initial value of an amount of prospective return of a steering angle after completion of parking; and performs first steering-angle-correction-control that controls the driving device so as to change by a first amount of correction of target steering angle to a side opposite to a current steering angle with respect to a magnitude of a current steering angle θs0 and a magnitude ° of the amount of prospective return.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a parking assistance system for a vehicle such as an automobile. [Background technology]

[0002] One type of parking assistance device for vehicles such as automobiles is known, which is configured to set a target parking position and a target route from the current location to the target parking position, and to move the vehicle to the target parking position and park it by automatically steering the steering wheels.

[0003] In parking assistance using a parking assistance device, when the vehicle starts from a parking position, it is preferable to control the steering angle to 0° or nearby so that the steering wheels are kept in a straight-ahead position or nearby so that the vehicle does not move in a direction not intended by the driver.

[0004] For example, paragraph

[0083] of the following Patent Document 1 describes a parking assistance device configured to set the steering angle to 0° when parking is complete by setting a target path consisting of an arc-clothoid curve-arc-straight line or an arc-clothoid curve-straight line. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-60223 Summary of the Invention

[0006] [Problem to be solved by the invention] When the road width or the space around the target parking position is limited, it is not possible to set a complex target route as with the parking assistance device described in Patent Document 1. To address this, it is conceivable to correct the steering angle to 0° or near 0° by automatically steering the steering wheels to a straight ahead position or near that position after parking is complete.

[0007] However, when the steering wheel is driven by automatic steering to a straight-ahead position or near that position after parking is completed and the steering force is released, the steering angle of the steering wheel changes to return to the direction opposite to the automatic steering direction due to the release of elastic deformation of the tires of the steering wheel and the steering member. Therefore, since the steering angle changes to return to the direction opposite to the automatic steering direction, the steering angle cannot be controlled to 0° or near it.

[0008] The present invention provides an improved steering assist device that increases the likelihood of bringing the steering angle closer to a target steering angle of 0° or close to that, by performing steering angle correction control that drives the steered wheels by automatic steering in anticipation of a return change in the steering angle.

[0009] [Means for solving the problems and effects of the invention] According to the present invention, a steering device (10) provided between a steering wheel (14) and steered wheels (front wheels 16FL, 16FR), a drive device (EPS device 12) that automatically steers the steered wheels by driving the steering device, and a control unit (drive assist ECU 50) that controls the drive device. And When a parking assistance command is received, the driving device is controlled so that the vehicle (102) moves to the target parking position. and a control unit, wherein the control unit (driving assistance ECU 50) includes a storage device (50A) that stores an initial value (θrp) of an expected return amount of the steering angle, and when parking is completed, performs a first steering angle correction control (S50) that controls the drive device (EPS device 12) so that the steering angle changes by the first target steering angle correction amount in the opposite direction from the target steering angle (0°) to the current steering angle, using the sum of the magnitude of the current steering angle (θs0) and the initial value (θrp) of the expected return amount as a first target steering angle correction amount (θc1). , a parking assist system (100) is provided.

[0011] According to the above configuration, when parking is completed, a first steering angle correction control is performed to control the drive device so that the steering angle changes in the opposite direction from the current steering angle with respect to the target steering angle by a first target steering angle correction amount, which is the sum of the magnitude of the current steering angle and the initial value of the expected return amount.

[0012] Therefore, the possibility of bringing the steering angle closer to the target steering angle can be increased compared to when the initial value of the expected return amount is not taken into consideration and the drive device is controlled so that the steering angle changes only by the magnitude of the current steering angle.

[0013] systemThe control unit (driver assistance ECU 50) calculates the steering angle (θsn) after the n-th steering angle correction control is completed, where n is a positive integer. Pre-set When the non-control range is exceeded, the control unit 100 calculates the magnitude (θrn) of the return amount of the n-th steering angle after the completion of the n-th steering angle correction control based on the magnitude (θrn-1) of the return amount of the steering angle after the completion of the n-th steering angle correction control and the magnitude of the steering angle (θsn) after the completion of the n-th steering angle correction control, calculates the (n+1)th target steering angle correction amount (θcn+1) based on the steering angle (θsn) after the completion of the n-th steering angle correction control and the magnitude (θrn) of the return amount of the n-th steering angle correction control, and performs (n+1)th steering angle correction control (S50) to control the drive device so that the steering angle changes by the (n+1)th target steering angle correction amount in the opposite direction from the steering angle (θsn) after the completion of the n-th steering angle correction control with respect to the target steering angle (0°) by the (n+1)th target steering angle correction amount.

[0014] The above composition According to In the nth or subsequent steering angle correction control, The magnitude of the steering angle return amount is calculated for each steering angle correction control, and the steering angle correction control can be repeatedly performed so that the steering angle approaches the target steering angle based on the steering angle after the steering angle correction control is completed and the magnitude of the steering angle return amount.

[0015] [Mode of the Invention] Furthermore, the present invention One In one aspect, the control unit (driving assistance ECU50) is configured not to perform the (n+1)th steering angle correction control (S50) when the steering angle (θsn) after the nth steering angle correction control is completed is within the non-control range (greater than -θe and less than θe) (S60), or when the steering angle (θsn) after the nth steering angle correction control is completed is outside the non-control range and n is greater than or equal to a reference value (ne) (S60, S70).

[0016] According to the above aspect, it is possible to prevent the steering angle correction control from being performed unnecessarily repeatedly.

[0017] Furthermore, in another aspect of the present invention, the memory device (50A) is a non-volatile readable and writable memory device, and the control unit (driving assistance ECU 50) is configured to update (S110) the initial value (θrp) of the expected return amount with the magnitude (θrn) of the return amount of the nth steering angle when the steering angle (θsn) after the nth steering angle correction control is completed is within the non-control range.

[0018] According to the above aspect, the initial value of the expected return amount can be updated based on the magnitude of the return amount of the steering angle when the steering angle correction control is performed, so that the steering angle correction control can be performed in accordance with the actual return change of the steering angle compared to when the initial value of the expected return amount is constant.

[0019] Furthermore, in another aspect of the present invention, the memory device (50A) stores the initial value (θrp) of the steering angle return amount for multiple outside air temperature categories, and the control unit (driving assistance ECU50) is configured to acquire information on the outside air temperature (Tout) when the steering angle (θsn) after the nth steering angle correction control is completed is within the non-control range, and update (S110) the initial value (θrp) of the expected return amount for the category to which the outside air temperature (Tout) belongs with the magnitude (θrn) of the nth steering angle return amount.

[0020] According to the above aspect, for each outside temperature range, the initial value of the expected return amount can be updated based on the magnitude of the return amount of the steering angle when the steering angle modification control is performed. Therefore, compared to when the initial value of the expected return amount for each outside temperature range is constant, it is possible to perform steering angle modification control in accordance with the actual return change of the steering angle.

[0021] Other objects, other features and attendant advantages of the present invention will be readily apparent from the following description of the preferred embodiments of the present invention, which is given with reference to the accompanying drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic configuration diagram showing a parking assistance device according to an embodiment. [Figure 2] 5 is a flowchart showing a routine for steering angle control after parking is completed in the first embodiment. [Figure 3] FIG. 4 is an explanatory diagram showing the operation of the first embodiment. [Figure 4] 10 is a flowchart showing a routine for steering angle control after parking is completed in a second embodiment. [Figure 5] 10 is a flowchart showing a main part of a routine for steering angle control after parking is completed in a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0024] 1, a parking assistance device 100 according to the embodiment is applied to a vehicle 102, and includes a steering device 10, an electric power steering ECU 40, and a driving assistance ECU 50. The vehicle 102 may be an autonomous vehicle, and includes a drive ECU 60, a braking ECU 70, and a meter ECU 80. In this specification, the electric power steering will be referred to as EPS (short for Electric Power Steering) as necessary.

[0025] Each ECU, such as the EPS ECU 40 and the driving assistance ECU 50, is an electronic control unit (ECU) that includes a microcomputer as its main component, and is connected to each other via a controller area network (CAN) 104 so that they can send and receive information. Each microcomputer includes a CPU, ROM, RAM, non-volatile memory, an interface, and the like. The CPU performs various functions by executing instructions (programs, routines) stored in the ROM. These ECUs may be integrated into a single ECU.

[0026] 1, the steering device 10 includes an EPS device 12 connected to an EPS ECU 40. The EPS device 12 is configured as a rack-and-pinion EPS device that is driven in response to the driver's operation of a steering wheel 14. A rack bar 18 of the EPS device 12 is connected to knuckle arms (not shown) of front wheels 16FL and 16FR, which are steered wheels, via tie rods 20L and 20R. The steering wheel 14 is connected to a pinion shaft 26 of the EPS device 12 via a steering shaft 22 and a universal joint 24.

[0027] In the illustrated embodiment, the EPS device 12 is a rack-assist type electric power steering device, and includes an electric motor 28 and a conversion mechanism 30, such as a belt type, that converts the rotation and torque of the electric motor 28 into a displacement and force in a reciprocating direction and transmits the displacement and force to the rack bar 18. The EPS device 12 generates a control torque by driving the rack bar 18 relative to a housing 32.

[0028] Therefore, the steering shaft 22, universal joint 24, pinion shaft 26, EPS device 12, and tie rods 20L, 20R constitute a steering transmission system 34 that transmits steering displacement and torque between the steering wheel 14 and the front wheels 16FL, 16FR. The EPS device 12 functions as a torque applying device that applies a control torque to the steering transmission system 34.

[0029] The steering shaft 22 is provided with a steering angle sensor 36 that detects the steering angle θs, and the pinion shaft 26 is provided with a steering torque sensor 38 that detects the steering torque Ts.

[0030] It is assumed that the steering angle θs and the steering torque Ts become positive values ​​when the vehicle 102 turns right due to the driver's steering operation. Therefore, the steering torque Ts becomes positive when the relative rotation of the member on the steering wheel 14 side and the member on the EPS device 12 side with respect to the torsion bar (not shown) of the steering torque sensor 38 corresponds to the direction in which the vehicle is turning right. In addition, the EPS device 12 may be a pinion assist type or a column assist type EPS device as long as it applies a control torque to the steering transmission system 34.

[0031] The EPS-ECU 40 controls the steering assist torque and reduces the driver's steering burden by controlling the EPS device 12 in a manner known in the art based on the steering torque Ts and vehicle speed V detected by a driving operation sensor 90 and a vehicle state sensor 92 (described later). The EPS-ECU 40 also controls the EPS device 12 to steer the front wheels 16FL and 16FR as needed. Thus, the EPS-ECU 40 and the EPS device 12 function as an automatic steering device 42 that automatically steers the front wheels as needed.

[0032] A camera sensor 52 and a radar sensor 54 are connected to the driving assistance ECU 50. The camera sensor 52 and the radar sensor 54 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 52 and the radar sensor 54 function as a target information acquisition device 56 that acquires information about targets at least ahead of the vehicle 102. Note that a LiDAR (Light Detection and Ranging) may be used instead of or in addition to the radar sensor 54.

[0033] Furthermore, a setting operator 58 is connected to the driving assistance ECU 50, and the setting operator 58 is provided in a position where it can be operated by the driver. Although not shown in Fig. 1, in this embodiment, the setting operator 58 includes a parking assistance switch, and the driving assistance ECU 50 executes parking assistance control when the parking assistance switch is on, and further executes steering angle control after parking is completed.

[0034] A drive unit 62 that accelerates the vehicle 102 by applying drive force to drive wheels not shown in Fig. 1 is connected to the drive ECU 60. Under normal circumstances, the drive ECU 60 controls the drive unit 62 so that the drive force generated by the drive unit 62 varies in response to the driving operation by the driver, and when a command signal is received from the driving assistance ECU 50, the drive ECU 60 controls the drive unit 62 based on the command signal.

[0035] The braking ECU 70 is connected to a braking device 72 that applies braking force to wheels not shown in Fig. 1 to decelerate the vehicle 102. Under normal circumstances, the braking ECU 70 controls the braking device so that the braking force generated by the braking device 72 changes in response to the braking operation by the driver, and when a command signal is received from the steering assist ECU 50, the braking ECU 70 performs automatic braking by controlling the braking device 72 based on the command signal.

[0036] The driving operation sensor 90 and the vehicle state sensor 92 are connected to the CAN 104. Information detected by the driving operation sensor 90 and the vehicle state sensor 92 (referred to as sensor information) is transmitted to the CAN 104. The driving operation sensor 90 includes a driving operation amount sensor and a braking operation amount sensor. The vehicle state sensor 92 includes a vehicle speed sensor, a longitudinal acceleration sensor, a lateral acceleration sensor, a yaw rate sensor, etc.

[0037] The driving assistance ECU 50 is a central control device that performs driving assistance control such as parking assistance control, steering angle control after parking is completed, and lane keeping control. In this embodiment, upon receiving a driving assistance command, the driving assistance ECU 50 cooperates with other ECUs to execute parking assistance control, which controls the automatic steering device 42 so that the vehicle 102 moves to a target parking position. Note that parking assistance control does not constitute the gist of the present invention and may be performed in any manner known in the technical field. Parking using parking assistance control may be parking performed with an occupant in the vehicle, or remote parking in which the driver gets out of the vehicle and the driver or another user operates a remote terminal.

[0038] Furthermore, when the vehicle 102 moves to the target parking position and stops there, completing the parking assist control, the driving assist ECU 50 executes steering angle control after parking is completed. As will be described in detail later, the steering angle control is Pre-set When the non-control range is exceeded, the steering angle correction control corrects the steering angle so that the steering angle approaches the target steering angle and falls within the non-control range. Note that the target steering angle in each embodiment described below is 0°.

[0039] [First embodiment] In the first embodiment, the microcomputer of the driving assistance ECU 50 includes a storage device 50A, which stores an initial value θr0 (positive constant) of the magnitude of the expected return amount of the steering angle used for steering angle control after parking is completed. Note that the initial value θr0 of the magnitude of the expected return amount may be, for example, a value obtained experimentally.

[0040] In the first embodiment, the ROM of the driving assistance ECU 50 stores a program for steering angle control after parking is completed, which program corresponds to the flowchart shown in Fig. 2. The CPU executes steering angle control after parking is completed in accordance with this program.

[0041] <Steering Angle Control Routine After Parking Completion in the First Embodiment> The steering angle control according to the flowchart shown in Fig. 2 is repeatedly executed at predetermined time intervals by the CPU of the driving assist ECU 50 when a parking assist switch (not shown in Fig. 1) of the setting operation device 58 is on and parking by the parking assist control is completed. Furthermore, when the steering angle control is started, n (a positive integer) indicating the number of times that steering angle correction control (described later) is to be executed is set to an initial value of 1. Note that the same applies to the steering angle control after parking is completed in other embodiments (described later).

[0042] First, in step S10, the CPU determines whether the absolute value of the steering angle θ is equal to or less than a non-control reference value θe (positive constant), i.e., whether steering angle modification control is unnecessary. If the CPU makes a positive determination, it terminates this control, and if the CPU makes a negative determination, it proceeds to step S20.

[0043] In step S20, the CPU sets the steering angle θs1 at the start of the first (n=1) steering angle modification control as the current steering angle θ.

[0044] In step S30, the CPU sets the magnitude θrn-1 of the return amount of the previous steering angle, which is used in the first steering angle modification control, to the initial value θr0 stored in the storage device 50A.

[0045] In step S40, the CPU calculates the target correction amount θcn for the n-th steering angle correction control according to the following equation (1): In the following equation (1), θsn-1 is the steering angle after the (n-1)th steering angle correction control has been performed, i.e., the steering angle when the steering angle returns due to the release of elastic deformation of the tires, etc. after the (n-1)th steering angle correction control, and signθsn-1 is the sign of the steering angle θsn-1. θrn-1 is the magnitude of the return amount of the steering angle after the (n-1)th steering angle correction control has been performed, and is the value calculated in the previous step 90. θcn=-(θsn-1+signθsn-1×θrn-1) …(1)

[0046] The target correction amount θc1 of the first steering angle correction control is calculated according to the following equation (2) because n is 1. θs0 is the steering angle when the parking assist control is completed, and therefore the steering angle at the start of the first steering angle correction control. θc1=-(θs0+signθs0×θrp) …(2)

[0047] In step S50, the CPU executes steering angle modification control by outputting a command signal to the EPS-ECU 40 so that the modification amount of the steering angle modification control becomes the target modification amount θcn. When the target modification amount θcn is a negative value, the EPS device 12 is controlled so that the steering angle θ changes in the left turning direction by θsn-1+signθsn-1×θrn-1. Conversely, when the target modification amount θcn is a positive value, the EPS device 12 is controlled so that the steering angle θ changes in the right turning direction by θsn-1+signθsn-1×θrn-1.

[0048] In step S60, the CPU waits a predetermined time (e.g., 100 msec) required for the steering angle to return after the steering angle modification control is completed, and then, similar to step S10, determines whether the absolute value of the steering angle θ (= θsn) is equal to or less than the non-control reference value θe. If the CPU makes a positive determination, it determines that the steering angle modification control is no longer necessary and terminates this control, but if the CPU makes a negative determination, it proceeds to step S70. The reference value in step S60 may be a value smaller than the reference value in step S10.

[0049] In step S70, the CPU determines whether n, which indicates the number of times the steering angle modification control has been executed, is equal to or greater than a reference value ne (a fixed positive integer such as 4). If the CPU makes a positive determination, it terminates this control, and if the CPU makes a negative determination, it proceeds to step S80.

[0050] In step S80, the CPU calculates the magnitude θrn of the steering angle return amount after the n-th steering angle modification control has been performed according to the following equation (3): When the CPU has completed the calculation of the steering angle return amount θrn, in step S90, the CPU increments n, which indicates the number of times the steering angle modification control has been performed, by 1, and then returns the control to step S40. θrn=θrn-1+|θsn| …(3)

[0051] <Example of operation of the first embodiment> Next, an example of the operation of the first embodiment will be described with reference to Fig. 3. Note that the time axis in Fig. 3 is intended to show the order of events, and does not indicate the exact elapsed time.

[0052] It is assumed that the parking assist control is completed when the vehicle 102 moves to the target parking position and stops there, and the steering angle control after parking is started. It is assumed that the steering angle θ at time t11, which is the start of the first steering angle correction control, is θs0, which is larger than the non-control reference value θe.

[0053] At time t12, as shown by the thick solid arrow, the EPS device 12 is controlled by the first steering angle correction control so that the steering angle θ changes by θs1+θr0 in the left turning direction. However, as the elastic deformation of the tires and the like is released, the steering angle θ returns beyond the vehicle's straight-ahead position (θ=0) as shown by the thick dashed arrow, and at time t13, it becomes θs1, which is larger than the non-controlled reference value θe.

[0054] Since the steering angle at the start of the second steering angle modification control is θs1, the magnitude of the return amount θr1 of the steering angle after the first steering angle modification control is θs1+θr0. As a result of the second steering angle modification control, as shown by the thick solid arrow, at time t21, the EPS device 12 is controlled so that the steering angle θ changes in the left turning direction by θs1+θr1=2θs1+θrp. As a result of the release of elastic deformation of the tires, etc., the steering angle θ becomes θs2 at time t22, as shown by the thick dashed arrow.

[0055] When the absolute value of θs2 is equal to or less than the non-control reference value θe, a positive determination is made in step S60, and the steering angle control after parking is terminated. On the other hand, when the absolute value of θs2 exceeds the non-control reference value θe, a negative determination is made in step S60, and steps S40 and S50 are executed. That is, the same steering angle correction control as the steering angle correction control at time t21 described above is executed.

[0056] Even if the steering angle modification control is repeatedly executed ne times, if the absolute value of the steering angle θsn after returning exceeds the non-control reference value θe, a positive determination is made in step S70, and the steering angle control after parking is terminated.

[0057] In the above example, the steering angle at the start of the first steering angle modification control is the steering angle in the right steering direction. If the steering angle at the start of the first steering angle modification control is the steering angle in the left steering direction, the steering angle modification control is performed in the same manner as in the above example, except that the direction of change of the steering angle by the steering angle modification control is reversed.

[0058] [Second embodiment] In the second embodiment and a third embodiment described later, the vehicle state sensor 92 includes an outside air temperature sensor that detects the outside air temperature Tout. The memory device 50A is a readable / writable nonvolatile memory device that stores an initial value θr0 of the magnitude of the expected return amount of the steering angle for a plurality of outside air temperature categories. As will be described later, the initial value θr0 of the magnitude of the expected return amount of the steering angle is updated as appropriate when steering angle control ends after parking is completed. [Table 1]

[0059] In the second embodiment, the ROM of the driving assistance ECU 50 stores a program for steering angle control after parking is completed, which program corresponds to the flowchart shown in Fig. 4. The CPU executes steering angle control after parking is completed in accordance with this program.

[0060] <Steering Angle Control Routine After Parking Completion in the Second Embodiment> As can be seen from a comparison between FIG. 4 and FIG. 2, steps other than steps S30, S60 and S110 are executed in the same manner as the corresponding steps in the first embodiment.

[0061] In step S30, the CPU reads information on the outside air temperature Tout detected by the outside air temperature sensor. Furthermore, by referring to Table 1 based on the outside air temperature Tout, the CPU identifies the expected steering angle return amount θrp for the temperature section to which the outside air temperature Tout belongs, and sets the steering angle return amount θr0 in the first steering angle correction control to the identified expected steering angle return amount θrp.

[0062] In step S60, the CPU determines whether the absolute value of the steering angle θ (= θsn) is equal to or less than the non-control reference value θe. If the CPU determines negative, it proceeds to step S70, as in the first steering angle correction control, but if the CPU determines positive, it proceeds to step S110.

[0063] In step S110, the CPU calculates the magnitude θrn of the steering angle return amount after the n-th steering angle modification control has been performed, as in step S80. Furthermore, the CPU reads information on the outside air temperature Tout detected by the outside air temperature sensor, and updates the initial value θr0 of the magnitude of the expected steering angle return amount for the temperature category to which the outside air temperature Tout belongs in Table 1 with the magnitude θrn of the steering angle return amount, and stores the updated value. Note that when step S110 is completed, this control ends.

[0064] In the above update, the initial value θr0 of the magnitude of the expected steering angle return amount for the temperature range to which the outside air temperature Tout belongs may be rewritten to the magnitude θrn of the steering angle return amount, or may be rewritten to the average value of the value stored in Table 1 and the magnitude θrn of the steering angle return amount.

[0065] [Third embodiment] In the third embodiment, the ROM of the driving assistance ECU 50 stores a program for steering angle control after parking is completed, which program corresponds to the flowchart shown in Fig. 5. The CPU executes steering angle control after parking is completed in accordance with this program.

[0066] <Steering Angle Control Routine After Parking Completion in Third Embodiment> As can be seen from a comparison between FIG. 5 and FIG. 4, steps other than steps S60, S100 and S120 are executed in the same manner as the corresponding steps in the second embodiment.

[0067] In step S60, the CPU determines whether the absolute value of the steering angle θ (= θsn) is equal to or less than the non-control reference value θe. If the CPU determines negative, it proceeds to step S70, as in the first steering angle correction control, but if the CPU determines positive, it proceeds to step S100.

[0068] In step S100, the CPU determines whether the steering angle θsn is on the same side as the previous steering angle θsn-1 with respect to the target steering angle of 0°. If the CPU makes a positive determination, it proceeds to step S110, as in the second steering angle correction control, and if the CPU makes a negative determination, it proceeds to step S120.

[0069] In step S120, the CPU reads information on the outside air temperature Tout detected by the outside air temperature sensor, updates the initial value θr0 of the magnitude of the expected return amount of the steering angle for the temperature category to which the outside air temperature Tout belongs in Table 1 with the magnitude θrn-1 of the return amount of the steering angle from the previous time, and stores the updated value. Note that the magnitude θrn of the return amount of the steering angle after the n-th steering angle correction control is performed is not calculated, and when step S120 is completed, this control ends.

[0070] In the above update, the initial value θr0 of the magnitude of the expected steering angle return amount for the temperature range to which the outside air temperature Tout belongs may be rewritten to the magnitude θrn-1 of the steering angle return amount, or may be rewritten to the average value of the value stored in Table 1 and the magnitude θrn-1 of the steering angle return amount.

[0071] As can be seen from the above explanation, according to each embodiment, when parking is completed, a first target steering angle correction amount θc1 is calculated, which is the sum of the magnitude of the current steering angle θs0 and the initial value θr0 of the magnitude of the expected return amount (S40). A first steering angle correction control is performed to control EPS device 12, which is a drive device, so that the steering angle θ changes by the first target steering angle correction amount in the direction opposite to the current steering angle with respect to the target steering angle of 0° (S50).

[0072] Therefore, the possibility of bringing the steering angle closer to the target steering angle can be increased compared to when the magnitude θr0 of the initial value of the expected return amount is not taken into consideration and the EPS device 12 is controlled so that the steering angle changes only by the magnitude of the current steering angle.

[0073] Furthermore, according to each embodiment, the magnitude θrn of the steering angle return amount after the nth steering angle modification control is completed is calculated based on the steering angle return amount θrn-1 after the (n-1)th steering angle modification control is completed and the magnitude of the steering angle θsn after the nth steering angle modification control is completed (S80). Furthermore, the (n+1)th target steering angle modification amount θcn+1 is calculated based on the steering angle θsn after the nth steering angle modification control is completed and the magnitude θrn of the steering angle return amount after the nth steering angle modification control is completed (S40). Furthermore, the EPS device 12 is controlled so that the steering angle changes by the (n+1)th target steering angle modification amount in the direction opposite to the steering angle θsn after the nth steering angle modification control is completed with respect to the target steering angle (S50).

[0074] Therefore, In the nth or subsequent steering angle correction control, The magnitude θrn of the steering angle return is calculated for each steering angle correction control, and the steering angle correction control (S50) can be repeatedly performed so that the steering angle approaches the target steering angle based on the steering angle θsn and the magnitude θrn of the steering angle return after the steering angle correction control is completed.

[0075] According to each embodiment, the steering angle θsn after the n-th steering angle correction control is completed is Pre-setIf the steering angle is within the non-control range (-θe or more and θe or less) (S60), the (n+1)th steering angle correction control is not performed, thereby preventing the steering angle correction control from being performed unnecessarily repeatedly.

[0076] Furthermore, even if the steering angle θsn after the n-th steering angle modification control is completed is outside the non-control range (S60), or even if n is equal to or greater than the reference value ne (S70), the (n+1)-th steering angle modification control is not performed. This makes it possible to prevent the steering angle modification control from being performed unnecessarily repeatedly in a situation where the steering angle cannot be brought close to the target steering angle due to an obstacle such as a curb.

[0077] In particular, according to the second and third embodiments, when the steering angle θsn after the n-th steering angle modification control is completed is within the non-control range (S60), the initial value of the anticipated return amount is updated by the magnitude of the return amount of the n-th steering angle (S110). Therefore, since the initial value of the anticipated return amount can be updated by the magnitude of the return amount of the steering angle when the steering angle modification control is performed, it is possible to perform steering angle modification control in accordance with the actual return change of the steering angle, compared to when the initial value of the anticipated return amount is constant.

[0078] Furthermore, according to the second and third embodiments, when the steering angle θsn after the n-th steering angle modification control is completed is within the non-control range (S60), information on the outside air temperature Tout is acquired, and the initial value of the expected return amount for the category to which that outside air temperature belongs is updated with the magnitude of the return amount of the n-th steering angle (S110). Thus, for each category of outside air temperature, the initial value of the expected return amount can be updated with the magnitude of the return amount of the steering angle when the steering angle modification control is performed. Because the elastic coefficient of tires and the like varies depending on the outside air temperature, steering angle modification control can be performed in accordance with the actual change in return of the steering angle, compared to when the initial value of the expected return amount for each category of outside air temperature is constant.

[0079] Furthermore, according to the third embodiment, when the steering angle θsn after the n-th steering angle modification control is completed is within the non-control range (S60) and the steering angle θsn is a value on the opposite side of the target steering angle of 0° from the previous steering angle θsn-1 (S100), the initial value of the expected return amount is updated with the magnitude of the return amount of the (n-1)th steering angle (S120). Therefore, in a situation where the return amount of the steering angle has become smaller than the correction amount of the steering angle due to the steering angle modification control, it is possible to prevent the initial value of the expected return amount from being updated with the smaller return amount of the steering angle.

[0080] Although the present invention has been described in detail above with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the above-described embodiments, and that various other embodiments are possible within the scope of the present invention.

[0081] For example, in each of the above-described embodiments, the target steering angle is 0°, but it may be any value or any range within the non-control range.

[0082] In addition, in the first embodiment, the initial value θr0 of the magnitude of the expected return amount is one regardless of the outside air temperature Tout, but as shown in Table 1, the initial value θr0 of the magnitude of the expected return amount of the steering angle may be set for multiple outside air temperature categories.

[0083] Furthermore, in the first embodiment, the initial value θr0 of the magnitude of the expected return amount is not updated, but as in the second and third embodiments, the magnitude θrn of the return amount of the steering angle after the steering angle correction control is performed may be calculated, and the initial value θr0 of the magnitude of the expected return amount may be updated with the magnitude θrn of the return amount of the steering angle.

[0084] In step 110 of the second and third embodiments, the initial value θr0 of the magnitude of the expected return amount of the steering angle for the temperature category to which the outside air temperature Tout belongs in Table 1 is updated with the return amount θrn of the steering angle and stored. When setting the initial value θr0 of the magnitude of the expected return amount of the steering angle in step 30 and updating the initial value θr0 in step 110, the type of tire, the age of tire use, the friction coefficient of the road surface, etc. may be taken into consideration. [Explanation of symbols]

[0085] 10...Steering device, 12...EPS device, 14...Steering wheel, 16FL, 16FR...Front wheels, 40...EPS ECU, 50...Driver assistance ECU, 50A...Storage device, 60...Drive ECU, 70...Braking ECU, 100...Steering assistance device, 102...Vehicle

Claims

1. a steering device provided between a steering wheel and steering wheels; a drive device that automatically steers the steering wheels by driving the steering device; and a control unit that controls the drive device, the control unit being configured to control the drive device so that the vehicle moves to a target parking position when a parking assistance command is received; a parking assist device configured such that, when parking is completed, the control unit includes a storage device that stores an expected return amount of the steering angle, and performs a first steering angle correction control that controls the drive device so that the steering angle changes by the first target steering angle correction amount in a direction opposite to the current steering angle with respect to the target steering angle, using a sum of the magnitude of the current steering angle and the expected return amount as a first target steering angle correction amount; the control unit, where n is a positive integer, calculates a magnitude of a return amount of the steering angle for an nth time after the completion of the n-1th steering angle correction control based on a magnitude of a return amount of the steering angle for an nth time after the completion of the n-1th steering angle correction control and a magnitude of the steering angle for an nth time after the completion of the n-1th steering angle correction control, and calculates a target steering angle correction amount for an n+1th time based on the steering angle for an nth time after the completion of the nth steering angle correction control and the magnitude of the return amount of the steering angle for an nth time, and performs an n+1th steering angle correction control to control the drive device so that the steering angle changes by the n+1th target steering angle correction amount in a direction opposite to the steering angle for an nth time after the completion of the nth steering angle correction control.

2. 2. The parking assistance device according to claim 1, wherein the control unit: When the steering angle after the n-th steering angle correction control is completed is within the non-control range, or When the steering angle after the n-th steering angle modification control is completed is outside the non-control range and n is equal to or greater than a reference value, The parking assistance device is configured not to perform the (n+1)th steering angle correction control.

3. 2. The parking assistance device according to claim 1, wherein the storage device is a non-volatile readable and writable storage device, and the control unit is configured to update the initial value of the expected return amount with the magnitude of the return amount of the n-th steering angle correction control when the steering angle after the n-th steering angle correction control is completed is within the non-control range.

4. 4. The parking assistance device according to claim 3, wherein the storage device stores initial values ​​of the return amount of the steering angle for a plurality of outside air temperature categories, and the control unit is configured to acquire outside air temperature information and update the initial value of the return amount of the steering angle for the category to which the outside air temperature belongs with the magnitude of the return amount of the steering angle for the nth time when the steering angle after the nth steering angle modification control is completed is within the non-control range.

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