Workload acquisition device

Abstract

The present invention addresses the problem of satisfactorily acquiring an amount of work in an amount of work acquisition device for acquiring the amount of work of an actuator. In this workload acquisition device, when a vehicle travels in a predetermined setting state in a state in which an actuator is controlled on the basis of a workload detected by a workload detection device, the workload acquisition device acquires a workload on the basis of a first physical quantity detected by a first physical quantity detection device. A change in the first physical quantity is greater than a change in the amount of work. Therefore, on the basis of the first physical quantity when the vehicle travels in the set state, it is possible to satisfactorily obtain the suitability of the workload detected by the workload detection device.

Description

Technical Field

[0001] The present invention relates to a workload acquisition device for acquiring the workload of an actuator. Background Art

[0002] In the steering system described in Patent Document 1, when the difference between the actual yaw rate and the front wheel yaw rate is less than a set value, or when the difference between the actual yaw rate and the rear wheel yaw rate is less than a set value, it is determined that the vehicle is in a neutral position. In addition, the deviation between the estimated steering angle estimated based on the yaw rate and the detected steering angle detected by the steering angle sensor when the vehicle is in a neutral position is stored. The set value is a value obtained by subtracting the error of the yaw rate sensor from the threshold value. The steering angle is the operating angle of the steering wheel.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-197073 Summary of the invention

[0004] An object of the present invention is to satisfactorily acquire the workload in a workload acquisition device for acquiring the workload of an actuator.

[0005] In the workload acquisition device involved in the present invention, when the actuator is controlled based on the workload detected by the workload detection device, and when the vehicle is traveling in a predetermined setting state, the workload is acquired based on the first physical quantity detected by the first physical quantity detection device.

[0006] The change in the first physical quantity is larger than the change in the workload. Therefore, if the workload detected by the workload detection device is based on the first physical quantity when the vehicle is running in a set state, the appropriateness of the workload can be well obtained. Thus, by setting the workload to be obtained based on the first physical quantity when the vehicle is running in a set state, the workload can be well obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram schematically showing the entirety of a workload acquisition device according to an embodiment of the present invention.

[0008] Figure 2 1 is a diagram schematically showing a rear-wheel steering system including a vehicle-mounted device as a constituent element of the above-mentioned workload acquisition device.

[0009] Figure 3 This is a diagram schematically showing the relationship between the number of rotations of the actuator and the change in the position of the steering rod in the vehicle-mounted device of the rear-wheel steering system.

[0010] Figure 4The figure schematically shows the relationship between the steering angles of the right rear wheel and the left rear wheel and the operation amount of the steering operation member when the vehicle is traveling straight in the above-mentioned rear-wheel steering system.

[0011] Figure 5 1 is a flowchart showing a rear wheel steering angle control program stored in a storage unit of the rear wheel steering system.

[0012] Figure 6 This is a flowchart schematically showing a calibration adjustment program stored in the storage unit of the workload acquisition device.

[0013] Figure 7 This is a flowchart showing a part of a workload acquisition program stored in a storage unit of the workload acquisition device.

[0014] Figure 8 2 is a flowchart showing another part of the workload acquisition procedure.

[0015] Fig. 9 This is a flowchart showing a forward operation amount acquisition program stored in the storage unit of the above-mentioned workload acquisition device.

[0016] Fig.10 10A and 10B are diagrams showing an aspect of the case where the position of the steering rod is adjusted during the rear wheel steering angle control in the above-mentioned rear wheel steering system.

[0017] Fig.11 11A and 11B represent Fig.10 A diagram showing a different form of the situation.

[0018] Fig.12 It is a diagram showing adjustment of the position of the steering rod when the vehicle is stopped.

[0019] Description of Reference Numerals

[0020] 4…Rear-wheel steering system; 6…EPS system; 22…Steering rod; 24…Moving force imparting device; 30…Actuator; 32…Nut; 34…Motion conversion mechanism; 50…Rear-wheel steering ECU; 52…Resolver; 54…Absolute angle sensor; 56…Database; 60…EPSECU; 64…Steering rod; 86…Yaw angular velocity sensor; 70…Steering operating component; 72…Operation state detection device; 92…Automatic driving assistance ECU; 94…Driving control ECU; 100…Main switch; 102…Surrounding environment acquisition device. DETAILED DESCRIPTION

[0021] Hereinafter, an operation amount acquisition device according to an embodiment of the present invention will be described with reference to the drawings. The operation amount acquisition device acquires the operation amount of an actuator included in a rear wheel steering system provided in a vehicle.

[0022] [Example]

[0023] like Figure 1 , 2 As shown, the vehicle includes a rear-wheel steering (Dynamic rear steering) system 4, an electric power steering (EPS) system 6, etc. The rear-wheel steering system 4 steers the left rear wheel 10L and the right rear wheel 10R, and the electric power steering system 6 steers the left front wheel 12L and the right front wheel 12R.

[0024] Hereinafter, the left rear wheel 10L and the right rear wheel 10R are simply referred to as left and right rear wheels 10L, 10R. The left front wheel 12L and the right front wheel 12R are simply referred to as left and right front wheels 12L, 12R. The electric power steering system 6 is simply referred to as the EPS system 6.

[0025] The rear-wheel steering system 4 includes a housing 20, a steering rod 22, a moving force imparting device 24, etc. The housing 20 extends in the width direction of the vehicle and is held by a vehicle body side member not shown. The steering rod 22 extends in a direction parallel to the axis L. Tie rods 26L and 26R are connected to both ends of the steering rod 22. The left and right rear wheels 10L and 10R are connected to the tie rods 26L and 26R, respectively. The axis L extends in the width direction of the vehicle. Hereinafter, the direction parallel to the axis L is referred to as the axis direction.

[0026] The steering rod 22 is held by the housing 20 so as to be relatively movable in the axial direction and relatively non-rotatable about the axis L. The steering rod 22 is held by the housing 20 by spline fitting or the like. A male thread portion 22s is provided at a middle portion of the steering rod 22.

[0027] The moving force imparting device 24 imparts a moving force as a force in the axial direction to the steering rod 22. The moving force imparting device 24 includes an actuator 30, a nut member 32, a motion conversion mechanism 34, etc. The actuator 30 includes an electric motor 36, etc. The electric motor 36 includes a stator 36a and a rotating shaft portion 36b. The nut member 32 is provided so as to be rotatable integrally with the rotating shaft portion 36b.

[0028] The stator 36a is fixedly arranged on the housing 20. A pair of bearings 38 and 39 are arranged between the rotating shaft portion 36b and the housing 20, and a bearing 44 is arranged between the nut member 32 and the housing 20. As a result, the rotating shaft portion 36b and the nut member 32 are held on the housing 20 in a manner that they cannot move relative to each other in the axial direction and can rotate relative to each other around the axis L. The rotating shaft portion 36b is arranged on the inner circumference side of the stator 36a so as to extend in the axial direction. The rotating shaft portion 36b is formed into a hollow shape, and the steering rod 22 passes through the central portion. The external thread portion 22s of the steering rod 22 is twisted into the internal thread portion 32s arranged on the inner circumferential surface of the nut member 32.

[0029] Furthermore, the actuator 30 may include a speed reducer that reduces the rotation speed of the electric motor 36 by a certain number of degrees.

[0030] In the present embodiment, the motion conversion mechanism 34 is constituted by the internal thread portion 32 s of the nut member 32 , the external thread portion 22 s of the steering rod 22 , and the like.

[0031] In the steering system, the nut component 32 is rotated by the actuator 30, thereby moving the steering rod 22 in the axial direction, and the left and right rear wheels 10L and 10R are steered via the tie rods 26L and 26R. In addition, in the present embodiment, for example, when the steering rod 22 is in the neutral position, the actuator 30 is in the neutral position. In addition, the steering angle of the left and right rear wheels 10L and 10R in this case is set to 0°. In addition, in the neutral position of the steering rod 22, the accumulated number of rotations of the actuator 30 is 0, and the displacement of the steering rod 22 from the neutral position is 0. Hereinafter, the steering angle of the left and right rear wheels 10L and 10R is sometimes referred to as the rear wheel steering angle. Similarly, the steering angle of the left and right front wheels 12L and 12R is sometimes referred to as the front wheel steering angle.

[0032] In this embodiment, the cumulative number of rotations of the actuator 30 from the neutral position and the displacement (movement amount) of the steering rod 22 from the neutral position correspond to the rear wheel steering angle on a one-to-one basis. For example, the rear wheel steering system 4 according to this embodiment is a system in which the steering rod 22 moves 0.1 mm and the left and right rear wheels 10L, 10R turn 0.1° with one rotation of the actuator 30 (nut member 32).

[0033] The rear-wheel steering system 4 is provided with a rear-wheel steering ECU (Electronic Control Unit) 50 mainly composed of a computer. The rear-wheel steering ECU 50 includes an execution unit 50c, a storage unit 50m, an input-output unit 50f, etc. The input-output unit 50f is connected to a resolver 52, an absolute angle sensor 54, a database 56, a lateral acceleration sensor 58, etc.

[0034] The resolver 52 is an example of a rotation number detection device that detects the rotation number of the actuator 30. In the present embodiment, the rotation numbers detected by the resolver 52 are accumulated to obtain the cumulative rotation number Nc. The resolver 52 can detect the rotation number of the actuator 30 with high accuracy. The tolerance of the resolver 52 is less than one rotation of the actuator 30. The tolerance refers to the allowed deviation of the value detected by the sensor.

[0035] The absolute angle sensor 54 detects the relative position of the steering rod 22 with respect to the housing 20. In the present embodiment, the absolute angle sensor 54 detects the displacement of the steering rod 22 from the neutral position. The neutral position of the steering rod 22 is acquired in advance before the vehicle is shipped from the factory, but it can also be acquired and learned after driving. The displacement of the steering rod 22 from the neutral position is sometimes referred to as the position of the steering rod 22 or the rod position.

[0036] like Figure 3 As shown, the absolute angle sensor 54 has a low detection accuracy of the displacement of the steering rod 22 from the neutral position. The tolerance of the absolute angle sensor 54 is ±0.15 mm. Therefore, it is difficult to detect the difference in the position of the steering rod 22 corresponding to the difference in the number of rotations of the actuator 30 by one rotation by the absolute angle sensor 54.

[0037] The database 56 can be connected to the rear-wheel steering ECU 50 (externally mounted) or built into the rear-wheel steering ECU 50. The database 56 stores the cumulative rotation number Ne when disconnected, the lever position Pe when disconnected, the operation amount d when moving forward, etc. The cumulative rotation number Ne when disconnected is the cumulative rotation number when the main switch 100 is switched from on to off. The lever position Pe when disconnected is the lever position when the main switch 100 is switched from on to off, and is obtained based on the cumulative rotation number Ne when disconnected. The operation amount d when moving forward is the operation amount of the steering operating member 70 from the neutral position when the vehicle is moving straight.

[0038] The lateral acceleration sensor 58 detects the lateral acceleration acting on the vehicle. When the vehicle is traveling straight on a flat road, the lateral acceleration is less than a set value, while when the vehicle is traveling straight but on an inclined road (slope), the lateral acceleration is greater than the set value. In addition, when the vehicle body is in a roll position, the lateral acceleration is also greater than the set value.

[0039] The EPS system 6 assists the operating force applied to the steering operating component 70 to steer the left and right front wheels 12L, 12R. The EPS system 6 applies an assist force corresponding to the operating amount θ of the steering operating component 70 from the neutral position. The operating amount θ of the steering operating component 70 from the neutral position is detected by the operating state detection device 72. The steering operating component 70 can be operated by the driver. The steering operating component 70 can be, for example, a steering wheel, but is not limited thereto. In addition, when the steering operating component 70 is a steering wheel, the operating amount can be referred to as an operating angle.

[0040] The EPS system 6 can include, for example, an electric power steering ECU 60, a housing 62, a steering rod 64, a moving force imparting device (not shown), etc. A steering operating member 70 is connected to a steering shaft 76 and a gear box 78. A rack portion (not shown) is provided on the steering rod 64. The steering operating member 70 is engaged with the rack portion of the steering rod 64 in the gear box 78. Hereinafter, the electric power steering ECU 60 is referred to as EPSECU 60.

[0041] The EPSECU 60 is mainly composed of a computer, and the input and output parts of the EPSECU 60 are connected to the operation state detection device 72, the resolver 82, the absolute angle sensor 84, the yaw rate sensor 86, etc. The yaw rate sensor 86 detects the yaw rate. The yaw rate is the number of degrees of rotation around the vertical axis of the vehicle. When the yaw rate detected by the yaw rate sensor 86 is less than the set value, it can be inferred that the vehicle is in a straight state.

[0042] In this embodiment, when the steering operating member 70 is in the neutral position, the steering rod 64 is considered to be in the neutral position and the front wheel steering angle is 0. In addition, when the operation amount of the steering operating member 70 is 1.5°, the front wheel steering angle is considered to be almost 0.1°.

[0043] In this embodiment, when the detection value γ of the yaw angular velocity sensor 86 is less than the set value γth for a set time or more, it is determined that the vehicle is in a straight-moving state. The straight-moving state is an example of a set state. In addition, when the vehicle is in a straight-moving state, the operation amount θ of the steering operating member 70 is detected by the operation state detection device 72, and the forward operation amount d is obtained. The forward operation amount d is appropriately updated and learned.

[0044] When the vehicle is in a running state, the EPSECU 60 executes the following operation at each set time. Fig. 9 The forward operation amount acquisition procedure is shown in the flowchart of FIG.

[0045] In step 201 (hereinafter referred to as S201, the same applies to other steps), it is determined whether the vehicle is in a straight-moving state. If the determination is yes, in S202, the operation amount θ of the steering operating member 70 is detected by the operation state detection device 72, and in S203, the forward operation amount d is acquired and stored through learning.

[0046] Multiple ECUs such as the rear-wheel steering ECU 50 and the EPSECU 60 are connected via a CAN (Controller area network) 90. A drive ECU 91, an automatic driving assistance (ADAS: Advanced Driver-Assistance System) ECU 92, a driving control ECU 94, etc. are connected to the CAN 90. These rear-wheel steering ECU 50, EPSECU 60, drive ECU 91, automatic driving assistance ECU 92, driving control ECU 94, etc. can communicate with each other.

[0047] The driving ECU 91 controls a driving device of the vehicle (not shown). A main switch 100 of the vehicle is connected to the driving ECU 91. Information indicating the on / off state of the main switch 100 is supplied to the rear wheel steering ECU 50 via the CAN 90. The main switch 100 may be, for example, an ignition switch.

[0048] The automatic driving assistance ECU92 assists the driving of the vehicle. The assistance of the driving of the vehicle includes the assistance of the driving of the vehicle. The automatic driving assistance ECU92 is connected to the surrounding environment acquisition device 102 and the like. The surrounding environment acquisition device 102 acquires objects located around the vehicle as a vehicle, that is, surrounding objects, etc., and acquires the relative position relationship between the vehicle and the surrounding objects, etc. The surrounding environment acquisition device 102 includes a camera, etc. Information indicating the relative position relationship between the vehicle and the surrounding objects, etc. is supplied to the rear wheel steering ECU50 and the like via the CAN90.

[0049] The driving control ECU 94 realizes the stabilization of the driving of the vehicle. Therefore, the driving control ECU 94 can be called a posture stabilization control (Vehicle Stability Control) ECU. The driving control ECU 94 is connected to a wheel speed sensor 104 and the like. The wheel speed sensor 104 is respectively provided on each of the left and right front wheels 12L, 12R, and the left and right rear wheels 10L, 10R. The wheel speed sensor 104 detects the rotation degrees of the left and right front wheels 12L, 12R, and the left and right rear wheels 10L, 10R, respectively. Based on the detection value of the wheel speed sensor 104, the driving speed v of the vehicle can be detected. Information indicating the driving speed v of the vehicle is supplied to the rear wheel steering ECU 50 and the like via the CAN 90.

[0050] The operation of the vehicle configured as above will be described.

[0051] The rear wheel steering ECU 50 determines the rear wheel target steering angle as the target steering angle of the left and right rear wheels 10L and 10R. The rear wheel target steering angle may be determined based on the relative positional relationship between the surrounding objects and the vehicle, or may be determined based on the operation amount θ of the steering operation member 70 and the vehicle's running speed v, etc. The rear wheel target steering angle may be determined in phase with the front wheel target steering angle, or in reverse phase with the front wheel target steering angle.

[0052] In the rear-wheel steering ECU 50, while the main switch 100 is turned on, the resolver 52 detects the rotation number of the actuator 30, and obtains the cumulative rotation number of the actuator 30. The position of the steering rod 22 is obtained based on the cumulative rotation number of the actuator 30, and the rear-wheel steering angle is obtained. Then, the actuator 30 is controlled so that the obtained rear-wheel steering angle approaches the rear-wheel target steering angle.

[0053] On the other hand, during the period when the main switch 100 is off, the resolver 52 does not detect the number of revolutions of the actuator 30. Therefore, for example, the cumulative number of revolutions when the main switch 100 is switched from on to off, that is, the cumulative number of revolutions when off Ne is stored in the database 56. In addition, as described above, the lever position when off Pe is also stored in the database 56. And then, when the main switch 100 is switched from off to on, the cumulative number of revolutions when off Ne can be considered to be the count start value Ncf to start counting the cumulative number of revolutions of the actuator 30.

[0054] Ne→Ncf

[0055] However, when the main switch 100 is turned off and the actuator 30 is stopped, for example, when an external force is applied to the vehicle body, the steering rod 22 may move in the rear-wheel steering system 4. This may be referred to as the steering rod 22 "moving" or "moving".

[0056] For example, when a large force is applied to the rear part of the vehicle body, it is conceivable that vibration is generated due to the vehicle being transported by a trailer, and the operation of the steering operating member 70 is locked. In these cases, the steering rod 64 is hardly moved in the EPS system 6, and the steering rod 22 is moved in the rear wheel steering system 4.

[0057] Thus, when "movement" occurs, the actual cumulative rotation number of the actuator 30 at the time when the main switch 100 is turned on is different from the cumulative rotation number Ne when it is turned off. Therefore, when the cumulative rotation number Ne when it is turned off is the count starting value Ncf, the cumulative rotation number of the actuator 30 is different from the actual cumulative rotation number. It is impossible to accurately obtain the rear wheel steering angle, and it is difficult to control the rear wheel steering angle with high accuracy.

[0058] Therefore, when the main switch 100 is changed from off to on, the position of the steering rod 22 is detected by the absolute angle sensor 54, and the detected rod position is set as the on-time rod position Ps. In addition, it is determined whether the absolute value of the difference between the off-time rod position Pe and the on-time rod position Ps |Pe-Ps| is greater than the determination threshold ΔPth. When the absolute value of the difference between the above values ​​|Pe-Ps| is greater than the determination threshold ΔPth, it is determined that "movement" has occurred during the period when the main switch 100 is off. The determination threshold ΔPth can be a size that is considered to cause the steering rod 22 to move due to an external force. The determination threshold ΔPth is one form of the second threshold.

[0059] If "movement" occurs while the main switch 100 is off, when the main switch 100 is switched from off to on, it can be considered that the steering lever 22 is in the on-time lever position Ps. Therefore, the cumulative rotation number Ns is obtained based on the on-time lever position Ps and is set as the on-time cumulative rotation number Ns. In addition, the on-time cumulative rotation number Ns is set as the count start value Ncf.

[0060] Ns→Ncf

[0061] Then, the cumulative number of rotations of the actuator 30 is counted from the count start value Ncf. This can be considered as the cumulative number of rotations Nc of the actuator 30 being corrected based on the detection value of the absolute angle sensor 54.

[0062] The rear wheel steering ECU 50 executes the operation at each predetermined set time. Figure 5 The rear wheel steering angle control program is shown in the flowchart.

[0063] In S101, it is determined whether the main switch 100 is switched from OFF to ON. If the determination is YES, S102 to S108 are executed.

[0064] In S102 and S103, the OFF-time cumulative rotation number Ne and the OFF-time lever position Pe are read from the database 56, and the ON-time lever position Ps is detected by the absolute angle sensor 54. In S104, it is determined whether the absolute value of the difference |Pe-Ps| between them is greater than the determination threshold ΔPth. If the determination is negative, in S105 and S106, the OFF-time cumulative rotation number Ne is set as the count starting value Ncf, and the counting of the cumulative rotation number Nc is started from the count starting value Ncf.

[0065] On the other hand, if the determination in S104 is YES, in S107, the key-on cumulative rotation number Ns is determined based on the key-on lever position Ps, and the key-on cumulative rotation number Ns is set as the count start value Ncf. In S108, the counting of the cumulative rotation number of the actuator 30 is started from the count start value Ncf.

[0066] On the other hand, if the determination in S101 is No, it is determined in S109 whether the main switch 100 is in the ON state. If the determination in S101 is No and the determination in S109 is Yes, S102 to S108 are not executed, and the processing after S110 is executed.

[0067] Next, in S110, it is determined whether the vehicle has started to travel. If it is determined to be yes, in S111, the rear wheel steering angle is controlled. The position of the steering rod 22 is obtained based on the cumulative number of rotations Nc, and the rear wheel steering angle is obtained. Then, the actuator 30 is controlled in such a way that the rear wheel steering angle approaches the rear wheel target steering angle.

[0068] In S112, it is determined whether the vehicle has finished traveling, and in S113, it is determined whether the main switch 100 has been turned off. If the determination in S112 is negative, S111 is repeatedly executed, and if the determination in S113 is negative, S110 to S113 are repeatedly executed. If the determinations in S112 and S113 are positive, S114 to S116 are executed.

[0069] In S114 , the counting of the cumulative number of revolutions Nc is ended. In S115 , the OFF-time cumulative number of revolutions Ne and the OFF-time lever position Pe are acquired. In S116 , the acquired values ​​are stored in the database 56 .

[0070] However, as described above, since the tolerance of the absolute angle sensor 54 is large, it is difficult to accurately detect a displacement of the steering rod 22 of less than 0.15 mm. Even if the cumulative rotation number is corrected based on the detection value of the absolute angle sensor 54, the corrected cumulative rotation number may be different from the actual cumulative rotation number. It is difficult to control the rear wheel steering angle with high accuracy.

[0071] For example, even if the rear wheel steering angle is controlled to be 0° and the front wheel steering angle is controlled to be 0°, there is a case where the rear wheel steering angle is not 0° even if the front wheel steering angle is controlled to be 0°. In this case, when it is desired to go straight, the steering operation member 70 is operated to turn the left and right front wheels 12L and 12R.

[0072] Moreover, when the front wheel steering angle is the same as the rear wheel steering angle, Figure 4 As shown in , the vehicle is swerving. Figure 4As shown, the yaw running refers to straight running in a state where the axis Lf extending in the front-rear direction of the vehicle body is inclined relative to the vehicle's traveling direction F. The vehicle runs straight toward the wheels 10L, 10R, 12L, 12R, so the vehicle's traveling direction becomes F. In contrast, the axis Lf extending in the front-rear direction of the vehicle body is inclined relative to the traveling direction F. The axis Lf extending in the front-rear direction of the vehicle body is referred to as a front-rear direction axis.

[0073] As can be seen from the above, when the rear wheel steering angle is large, the forward operation amount d, which is the operation amount of the steering operation member 70, becomes larger than when it is small. In addition, if the forward operation amount d is used, the front wheel steering angle can be obtained, and similarly, the rear wheel steering angle can be obtained.

[0074] In this embodiment, the rear wheel steering angle is obtained based on the operation amount of the steering operation member 70 in a state where the rear wheel steering angle is controlled so that the vehicle moves straight (the forward operation amount d). In addition, the actual cumulative rotation number of the actuator 30 is obtained based on the rear wheel steering angle, and the cumulative rotation number is corrected. In this embodiment, the cumulative rotation number Nc of the actuator 30 is corrected based on the forward operation amount d.

[0075] When the steering operating member 70 is a steering wheel, the steering wheel 70 can be rotated from the neutral position to one side by about 360° to 540°. In addition, even when the steering operating member 70 is not a steering wheel, the maximum operation amount of the steering operating member 70 to one side is generally greater than the maximum steering angle of the left and right rear wheels 10L, 10R to one direction. The operation state detection device 72 can detect the operation amount of the steering operating member 70 up to 1.5° with high accuracy. The tolerance of the operation state detection device 72 is less than ±1.5°.

[0076] Thus, for example, when the operation amount d is ±1.5° during forward movement, it can be estimated that the left and right front wheels 12L, 12R and the left and right rear wheels 10L, 10R are turned by ±0.1°. This is a difference of ±1 rotation of the cumulative number of rotations Nc of the actuator 30 in the rear-wheel steering system 4. Therefore, when the operation amount d is ±1.5° during forward movement, the cumulative number of rotations Nc is corrected by ±1.

[0077] In addition, the numerical values ​​such as 0.1°, 1.5°, and 0.1 mm described in this specification are merely examples and are not limited thereto. These numerical values ​​may also be changed by changing the specifications of the rear wheel steering system 4 and the EPS system 6 .

[0078] In the present embodiment, the absolute value |d-dm| of the difference between the forward operation amount d detected when the main switch 100 is turned on this time and the forward operation amount dm stored in the database 56 when the main switch 100 was turned on last time is obtained. Then, it is determined whether the absolute value |d-dm| of the difference in the forward operation amount is greater than the first threshold value dth, and whether the movement amount conversion value ΔPd, which is a value obtained by converting the absolute value |d-dm| of the difference in the forward operation amount into the movement amount of the steering rod 22, is less than the third threshold value δ.

[0079] When the absolute value of the difference in the forward movement operation amount |d−dm| is larger than the first threshold value dth and the movement amount conversion value ΔPd is smaller than the third threshold value δ, the cumulative rotation number Nc is corrected based on the forward movement operation amount dm.

[0080] |d-dm|>dth

[0081] ΔPd<δ

[0082] The first threshold dth is set to a value that indicates that the vehicle is in a yaw driving state. The forward operation amount dm stored in the database 56 can be considered to be almost 0°. This is because, in contrast, when the vehicle is in a yaw driving state this time, the absolute value of the forward operation amount d becomes larger. The third threshold δ is set to a value determined based on the tolerance of the absolute angle sensor 54. This is because, when the main switch 100 is switched from off to on, the difference above the tolerance of the absolute angle sensor 54 has been corrected, so when the difference above the tolerance of the absolute angle sensor 54 is generated again, it can be considered that the reliability of the value of the forward operation amount d is low.

[0083] When the vehicle leaves the factory or undergoes a vehicle inspection, Figure 6 The calibration adjustment procedure is shown in the flowchart of FIG. The calibration adjustment is performed on both the left and right front wheels 12L, 12R and the left and right rear wheels 10L, 10R.

[0084] In S1, the calibration adjustment mode is set in the rear wheel steering system 4. In S2, the data such as the forward operation amount d stored in the database 56 are deleted. In S3, the counting of the cumulative number of rotations of the actuator 30 is started, and in S4, the calibration adjustment is performed.

[0085] Furthermore, in S5, it is determined whether the vehicle has started traveling. In S6 and 7, based on the lateral acceleration detected by the lateral acceleration sensor 58, it is determined whether the road surface is a special road surface such as an inclined surface, and whether the vehicle is in a roll posture or other conditions. This is because, even if the vehicle is in a straight-moving state, when the lateral acceleration is greater than the set value, there is a high possibility that the operation amount θ of the steering operating component 70 in the straight-moving state of the vehicle does not accurately reflect the rear wheel steering angle. In the case where the road surface on which the vehicle is traveling is not a special road surface and the lateral slope of the vehicle is small, the determination in S6 and 7 is no. In the case where the determination in S6 and 7 is no, in S8 and 9, the operation amount d when moving forward is received and stored in the database 56.

[0086] As described above, in the present embodiment, when the vehicle is traveling straight and is not tilted, information indicating the forward movement operation amount d supplied from the EPSECU 60 is received, stored in the database 56 , and updated.

[0087] In S10, it is determined whether the vehicle has finished traveling, and in S11, it is determined whether the main switch 100 has been turned off. When the forward operation amount d is acquired once from the start of traveling to the end of traveling, S10 and S11 are repeatedly executed until the determination of S10 and S11 becomes yes. On the other hand, when the forward operation amount d is acquired multiple times, S5 to S11 can be repeatedly executed while the determination of S10 and S11 is no.

[0088] If the determination in S10 and S11 is YES, the counting of the number of revolutions is terminated in S12, the OFF cumulative number of revolutions Ne and the OFF lever position Pe are acquired in S13, and stored in the database 56 in S14. Thereafter, the calibration adjustment mode is canceled in S15.

[0089] The rear wheel steering ECU 50 executes the operation at each predetermined set time. Figure 7 , 8 The workload acquisition procedure is shown in the flowchart.

[0090] In S21, it is determined whether the main switch 100 is switched from off to on. If the determination is yes, in S22, the cumulative rotation number Ne when off and the lever position Pe when off are read, and in S23, the lever position Ps when on is detected by the absolute angle sensor 54. In S24, it is determined whether the absolute value of the difference between the lever position Pe when off and the lever position Ps when on is greater than the determination threshold value ΔPth. If the determination is yes, the processing after S51 is executed. If the determination in S24 is no, in S25, the cumulative rotation number Ne when off is set to the count start value Ncf to start counting the rotation number of the actuator 30.

[0091] If the determination in S21 is NO, it is determined in S26 whether the main switch 100 is turned on. If the determination is YES, S22 to S25 are not executed, and the processing after S27 is executed.

[0092] In S27 to S36, S5 to S14 of the calibration adjustment program are executed in the same manner. Figure 5 The rear wheel steering angle control routine shown in the flowchart of FIG. 2 is executed while steps S27 to S31 are executed. After the start of traveling, when the vehicle is not tilted, the forward operation amount d supplied from the EPSECU 60 is stored in the database 56 .

[0093] When the driving is finished and the main switch 100 is turned off, the counting of the number of revolutions is terminated in S34. In this step, the rear wheel steering control is also terminated. In S35, the cumulative number of revolutions Ne and the lever position Pe when the vehicle is turned off are obtained and stored in the database 56 in S36.

[0094] On the other hand, if the determination in S24 is YES, in S51, the cumulative rotation number Ns at the time of connection is acquired based on the lever position Ps at the time of connection, and the cumulative rotation number Ns at the time of connection is set as the count start value Ncf. Furthermore, in S52, the counting of the cumulative rotation number of the actuator 30 is started from the count start value Ncf. When the vehicle starts traveling and the determination in S53 becomes YES, the rear wheel steering ECU 50 controls the rear wheel steering angle based on the cumulative rotation number Nc counted in S52, and executes the processing after S54.

[0095] In S54 and 55, it is determined whether the vehicle is tilted based on the lateral acceleration. If the above determination is negative, in S56, the forward operation amount d obtained when the main switch 100 is turned on this time is supplied to the EPS system 6 via CAN90. In S57, it is determined whether the absolute value |d-dm| of the difference between the forward operation amount d and the forward operation amount (the previous value of the forward operation amount) dm stored in the database 56 is greater than the first threshold dth. If the determination is negative, in S58 and 59, it is determined whether the state in which the absolute value |d-dm| of the difference is less than the first threshold dth has continued for more than a set time. When S59 is initially executed, the determination result is negative, but if S54 to 59 are repeatedly executed and a set time has passed, there is a case where the determination of S59 becomes positive. When the determination of S59 becomes positive, it is determined that the correction based on the lever position Ps at the time of turning on is appropriate, and the process returns to Figure 7 Then, the current forward movement operation amount d is obtained and stored in the database 56 .

[0096] On the other hand, if the determination in S57 is yes, in S60, the absolute value of the difference |d-dm| is converted into a value ΔPd of the movement amount of the steering rod 22. In S61, it is determined whether the converted value ΔPd is less than or equal to the third threshold value δ. If the determination is yes, in S62, the cumulative rotation number Nc is corrected based on the forward operation amount d. In this embodiment, the cumulative rotation number Nc is often corrected by ±1.

[0097] In S62, the actual position of the steering lever 22 is also changed along with the correction of the cumulative number of revolutions Nc. The steering lever 22 is moved so that the lever position corresponding to the corrected cumulative number of revolutions Nc and the lever position detected by the absolute angle sensor 54 coincide with each other.

[0098] In the control of the rear wheel steering angle, it is assumed that the range determined by the control value and the set value of the rear wheel steering angle at the time of the correction start instruction. Fig.10 As shown in FIG. 1 , the control value of the rear wheel steering angle can be changed from a value within the range to a value outside the range as a starting condition to slowly move the steering rod 22. Fig.11 As shown, the steering column 22 can be slowly moved by setting the control value of the rear wheel steering angle from a value outside the range to a value within the range as a starting condition.

[0099] This can reduce the driver's sense of discomfort and move the steering rod 22. In addition, the relationship between the detection value of the absolute angle sensor 54 and the cumulative number of rotations Nc can be well maintained.

[0100] After S62 is executed, the processing after S32 is executed.

[0101] On the other hand, if the determination of S61 is negative, it is determined that the reliability of the forward operation amount d is low, and the process returns to S54. The forward operation amount d is acquired again. If the determination of S61 becomes positive by repeatedly executing S54 to 60, S62 is executed, and S32 to 36 are executed.

[0102] Thus, in this embodiment, the presence or absence of "movement" of the steering rod 22 during the period when the main switch 100 is off is determined based on the detection value of the absolute angle sensor 54. Then, if it is determined that "movement" has occurred, the cumulative number of rotations is corrected based on the on-time rod position detected by the absolute angle sensor 54 when the main switch 100 is turned on. As a result, even if "movement" occurs, a decrease in the control accuracy of the rear wheel steering angle can be suppressed.

[0103] In addition, in the control of the rear wheel steering angle, the cumulative rotation number Nc is corrected based on the forward operation amount d when the rear wheel steering angle is not 0° and the vehicle is in a yaw driving state. Therefore, for the part where the cumulative rotation number cannot be corrected based on the detection value of the absolute angle sensor 54, the cumulative rotation number Nc of the actuator 30 can also be corrected. As a result, the reduction in the control accuracy of the rear wheel steering angle can be well suppressed.

[0104] Furthermore, the position correction of the steering rod 22 can be performed during the stop. Fig.12 As shown, the steering rod 22 is forcibly moved while the vehicle is stopped. It is considered that even if the steering rod 22 is forcibly moved while the vehicle is stopped, the driver's sense of discomfort is small.

[0105] In addition, in the above-mentioned embodiment, the case where the forward operation amount d is supplied from the EPSECU 60 to the rear-wheel steering ECU 50 is described, but it is not limited to this. For example, when the rear-wheel steering system 4 and the EPS system 6 are combined into a vehicle steering system, both the learning of the forward operation amount d and the correction of the accumulated rotation number Nc are performed in the vehicle steering system.

[0106] Furthermore, the forward-moving operation amount d is also acquired by the automatic driving assist ECU 92 and the traveling control ECU 94. Therefore, the forward-moving operation amount d can be supplied from the automatic driving assist ECU 92 and the traveling control ECU 94 to the rear-wheel steering ECU 50.

[0107] In addition, the fact that the vehicle is in a yawed driving state can be obtained using a camera included in the surrounding environment acquisition device 102. For example, it can be obtained based on changes in the captured image on the axis of the camera. The camera is installed in the front center of the vehicle facing forward.

[0108] When the vehicle is in a straight-moving state and the vehicle's traveling direction F coincides with the longitudinal axis Lf, the captured image of the same object should always be located on the camera's reference area. In contrast, when the vehicle is in a yawed driving state and the longitudinal axis Lf is inclined relative to the traveling direction F, the captured image of the same object is located in a portion separated from the camera's reference area. Based on this, the vehicle can be obtained when the vehicle is in a yawed driving state and the longitudinal axis Lf of the vehicle is inclined relative to the traveling direction F of the vehicle.

[0109] Furthermore, it is possible to obtain the fact that the vehicle is in a yawed driving state based on each position detected by each of two position detection devices (for example, GPS receivers) spaced apart in the width direction of the vehicle, or each movement trajectory based on changes in each position.

[0110] In addition, the actuator 30 may include a speed reducer. Furthermore, the vehicle-mounted device is not limited to the rear-wheel steering system or the components of the rear-wheel steering system. Furthermore, the set state is not limited to the straight driving state, and may also be a turning driving state or the like.

[0111] As described above, in this embodiment, the workload acquisition device is composed of the rear wheel steering ECU 50, the resolver 52, the absolute angle sensor 54, the lateral acceleration sensor 58, the EPSECU 60, the operation state detection device 72, the yaw angular velocity sensor 86, etc.

[0112] The forward operation amount d of the steering operating member 70 is an example of a slope-related value as the slope of the front-rear axis Lf relative to the vehicle's traveling direction F. In addition, the moving force imparting device 24 or the rear-wheel steering system 4 corresponds to the vehicle-mounted device. The cumulative number of revolutions of the actuator 30 corresponds to the workload, and the workload detection device is composed of the resolver 52 and the like. In addition, the forward operation amount d of the steering operating member 70 corresponds to the first physical quantity, and the operation state detection device 72 corresponds to the first physical quantity detection device and the slope-related value detection unit. The position of the steering rod 22 corresponds to the second physical quantity, and the absolute angle sensor 54 corresponds to the second physical quantity detection device and the rod position detection unit. The rod position Pe when disconnected corresponds to the second physical quantity when disconnected, and the rod position Ps when connected corresponds to the second physical quantity when connected and the detection rod position. In addition, the detection slope-related value corresponds to the current value d of the forward operation amount, and the reference slope-related value corresponds to the forward operation amount dm stored in the database 56.

[0113] The rear wheel steering ECU 50 and the like constitute a control device, and the portion storing S21 to 62 and the portion executing S21 to 62 and the like constitute a workload correction portion. The portion storing S24 and the portion executing S24 and the like constitute a movement determination portion.

[0114] Furthermore, the present invention can be implemented in various forms after various changes and improvements are made based on the knowledge of those skilled in the art.

[0115] [Patentable inventions]

[0116] The inventions for which patents can be applied are described in the following items.

[0117] (1) A workload acquisition device, in a rear-wheel steering system, acquires the workload of an actuator, the rear-wheel steering system comprising: a steering rod extended in the width direction of the vehicle; and the actuator capable of moving the steering rod in the width direction, the rear-wheel steering system moves the steering rod in the width direction by the actuator, thereby steering at least one of the left rear wheel and the right rear wheel of the vehicle connected to the steering rod, wherein the rear-wheel steering system comprises a control device that controls the steering angle of at least one of the left rear wheel and the right rear wheel based on the workload of the actuator, and the workload acquisition device comprises The invention comprises: a workload detection device for detecting the workload of the actuator; a slope-related value detection unit for detecting a slope-related value associated with the slope of the front-rear axis of the vehicle relative to the traveling direction of the vehicle; and a workload correction unit for correcting the workload of the actuator detected by the workload detection device based on the slope-related value detected by the slope-related value detection unit, i.e., the detected slope-related value, when the control unit controls the steering angle of at least one of the left rear wheel and the right rear wheel in such a manner that the vehicle goes straight based on the workload of the actuator detected by the workload detection device.

[0118] The slope-related value is the slope of the longitudinal axis of the vehicle relative to the vehicle's traveling direction, or a value that corresponds 1:1 to the tilt. When the rear wheel steering angle is controlled so that the vehicle goes straight, the rear wheel target steering angle is often set to 0°.

[0119] (2) A workload acquisition device according to item (1), wherein when the absolute value of the difference between the detected slope associated value and the slope associated value of the vehicle in a straight-moving state obtained and stored in advance, i.e., a reference slope associated value, is greater than a first threshold value, the workload correction unit corrects the workload of the actuator based on the detected slope associated value.

[0120] The reference slope-related value may be, for example, a slope-related value obtained when the main switch was turned on in the past. The reference slope-related value is a value when the vehicle is not in a yaw state. Therefore, the first threshold may be a value that indicates that the vehicle is yawing.

[0121] (3) A workload acquisition device according to item (1) or (2), wherein the rear-wheel steering system includes a rod position detection unit for detecting the position of the steering rod, i.e., the displacement from the neutral position, and when the absolute value of the difference between the position of the steering rod obtained based on the workload of the actuator detected by the workload detection device when the main switch of the vehicle is switched from on to off, i.e., the rod position when off, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, i.e., the rod position when on, is greater than a second threshold value, the workload correction unit corrects the workload of the actuator based on the rod position when on.

[0122] The second threshold value may be a value that can be determined as a steering lever movement. In addition, the second threshold value is preferably a value greater than a tolerance of the lever position detection unit.

[0123] (4) A workload acquisition device according to item (3), wherein, in a state where the steering angle of at least one of the left rear wheel and the right rear wheel is controlled by the control device based on the workload of the actuator corrected according to the lever position when the vehicle is turned into the driving state, i.e., the corrected workload, when the absolute value of the difference between the detected slope-related value detected by the slope-related value detection unit and the slope-related value of the vehicle in the straight-ahead state obtained and stored in advance, i.e., the reference slope-related value, is greater than a first threshold value, and when the absolute value of the difference between the detected slope-related value and the reference slope-related value converted into a value of the movement of the steering rod is less than a third threshold value, the workload correction unit corrects the corrected workload based on the detected slope-related value.

[0124] The third threshold value may be a value determined based on the tolerance of the lever position detection unit. The corrected workload corresponds to the cumulative number of rotations counted by the execution of S107 and S108 in the above-described embodiment.

[0125] (5) A workload acquisition device according to any one of items (1) to (4), wherein the rear-wheel steering system includes a rod position detection unit that detects the position of the steering rod, i.e., the displacement from the neutral position, and the workload acquisition device includes a movement determination unit, wherein when the absolute value of the difference between the position of the steering rod obtained based on the workload of the actuator detected by the workload detection device when the main switch of the vehicle is switched from on to off, i.e., the rod position when off, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, i.e., the rod position when on, is greater than a second threshold value, the movement determination unit determines that the steering rod has been moved by an external force while the main switch is off.

[0126] (6) A workload acquisition device according to any one of items (1) to (5), wherein the actuator includes a motor, and the workload detection device detects the number of rotations of the actuator to obtain the cumulative number of rotations of the actuator from a neutral position.

[0127] (7) The workload acquisition device according to any one of items (1) to (6), wherein:

[0128] The slope-related value detection unit detects, as the slope-related value detection unit, at least one of (a) the amount of operation of a steering operating component provided on the vehicle from a neutral position, and (b) the slope of an axis of a camera mounted in a manner capable of photographing the front of the vehicle relative to a direction of travel of the vehicle.

[0129] (8) A workload acquisition device according to any one of items (1) to (7), wherein the rear-wheel steering system includes a rod position detection unit that detects the position of the steering rod, i.e., the displacement from the neutral position, and the change in the slope-related value that changes with the change in the set workload change of the actuator is greater than the tolerance of the slope-related value detection unit, and the movement of the steering rod that changes with the change in the set workload change is less than the tolerance of the rod position detection unit.

[0130] The above-mentioned form is a basic requirement for expressing the performance of each detection unit. The set operation variation can be, for example, the set rotation number of the actuator. In the above-mentioned embodiment, the set rotation number is 1.

[0131] (9) A steering system, wherein the steering system includes: a steering rod extending in the width direction of the vehicle and connected to the wheels; an actuator capable of moving the steering rod in the width direction; a workload detection device for detecting the workload of the actuator; a rod position detection unit for detecting the position of the steering rod, i.e., the displacement from the neutral position of the steering rod; and a workload correction unit for correcting the workload based on the on-time rod position when the absolute value of the difference between the position of the steering rod obtained based on the workload when a main switch of the vehicle is switched from on to off, i.e., the off-time rod position, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, i.e., the on-time rod position, is greater than a second threshold value.

[0132] The steering system described in this item can adopt the features described in any one of items (1) to (8).

[0133] (10) A steering system, wherein the steering system includes: a steering rod extending in the width direction of the vehicle and connected to the wheels; an actuator capable of moving the steering rod in the width direction; a workload detection device for detecting the workload of the actuator; a rod position detection unit for detecting the position of the steering rod, i.e., the displacement from the neutral position of the steering rod; and a movement determination unit for determining that the steering rod has been moved in the width direction by an external force while the main switch is off, when the absolute value of the difference between the position of the steering rod obtained based on the workload when a main switch of the vehicle is switched from on to off, i.e., the rod position when off, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, i.e., the rod position when on, is greater than a second threshold value.

[0134] The steering system described in this item can adopt the features described in any one of items (1) to (9).

[0135] (11) A workload acquisition device, comprising: a workload detection device for detecting the workload of an actuator of a vehicle-mounted device mounted on a vehicle; a first physical quantity detection device for detecting a first physical quantity which is a physical quantity corresponding to the workload on a one-to-one basis; and a workload correction unit for correcting the workload based on the first physical quantity detected by the first physical quantity detection device, wherein, when the actuator is controlled based on the workload detected by the workload detection device and the vehicle is traveling in a predetermined setting state, the workload correction unit corrects the workload of the actuator based on the value detected by the first physical quantity detection device.

[0136] An example of the first physical quantity detection device is a slope-related value detection unit, and an example of the set state of the vehicle is the forward state of the vehicle. In addition, an example of the vehicle-mounted device is a rear-wheel steering system or a component of the rear-wheel steering system. The first physical quantity detection device and the vehicle-mounted device are not limited to the above-mentioned embodiments.

[0137] The workload acquisition device described in this item can adopt the technical features described in any one of items (1) to (10).

[0138] (12) A workload acquisition device according to item (11), wherein the workload acquisition device includes a second physical quantity detection device, the second physical quantity detection device detects a second physical quantity and is different from the first physical quantity detection device, the second physical quantity is a physical quantity different from the first physical quantity and corresponds to the workload on a one-to-one basis, and when the absolute value of the difference between the value obtained by converting the workload detected by the workload detection device into the second physical quantity, i.e., the second conversion value, and the value detected by the second physical quantity detection device, i.e., the second detection value, is less than a fourth threshold value, the workload correction unit does not correct the workload based on the second detection value, and when the workload is greater than the fourth threshold value, the workload is corrected based on the second detection value.

[0139] In the above embodiment, the second detection value corresponds to the on-time lever position Ps, and the second conversion value corresponds to the off-time lever position Pe. The fourth threshold value corresponds to the second threshold value.

[0140] (13) A workload acquisition device according to item (11) or (12), wherein the workload correction unit is configured as follows: when the vehicle is traveling in a set state while the vehicle-mounted device is controlled based on the corrected workload corrected according to the second detection value, when the absolute value of the difference between the value detected by the first physical quantity detection device, i.e., the first detection value, and the first physical quantity obtained and stored in advance when the vehicle is traveling in the set state, i.e., the first reference value, is converted into a value after converting the second physical quantity, i.e., the differential second conversion value, is greater than a fifth threshold value, it is determined that the first detection value is abnormal; when it is less than the fifth threshold value, the corrected workload is corrected based on the first detection value.

[0141] The fifth threshold value corresponds to the third threshold value.

Claims

1. A workload acquisition device for acquiring the workload of an actuator in a rear-wheel steering system, the rear-wheel steering system comprising: A steering rod is arranged to extend in the width direction of the vehicle; and The actuator is capable of moving the steering rod in the width direction, The rear wheel steering system moves the steering rod in the width direction by the actuator, thereby steering at least one of the left rear wheel and the right rear wheel of the vehicle connected to the steering rod. in, The rear-wheel steering system includes a control device for controlling a steering angle of at least one of the left rear wheel and the right rear wheel based on an amount of work of the actuator. The workload acquisition device comprises: A workload detection device for detecting the workload of the actuator; a slope-related value detection unit that detects a slope-related value associated with a slope of a front-rear axis of the vehicle relative to a traveling direction of the vehicle; and The workload correction unit corrects the workload of the actuator detected by the workload detection device based on the slope-related value detected by the slope-related value detection unit, that is, the detected slope-related value, when the control device controls the steering angle of at least one of the left rear wheel and the right rear wheel in such a way that the vehicle becomes a straight-moving state based on the workload of the actuator detected by the workload detection device.

2. The workload acquisition device according to claim 1, wherein: When the absolute value of the difference between the detected slope-related value and a previously acquired and stored reference slope-related value of the vehicle in a straight-moving state is greater than a first threshold, the workload correction unit corrects the workload of the actuator based on the detected slope-related value.

3. The workload acquisition device according to claim 1 or 2, wherein: The rear wheel steering system includes a lever position detection unit for detecting the position of the steering lever, that is, the displacement from the neutral position. When the absolute value of the difference between the position of the steering rod obtained based on the workload of the actuator detected by the workload detection device when the main switch of the vehicle is switched from on to off, that is, the rod position when off, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, that is, the rod position when on, is greater than a second threshold, the workload correction unit corrects the workload of the actuator based on the rod position when on.

4. The workload acquisition device according to claim 3, wherein: In a state where the control device controls the steering angle of at least one of the left rear wheel and the right rear wheel in such a way that the vehicle becomes in a straight-ahead state based on the workload of the actuator corrected according to the lever position when it is turned on, i.e., the corrected workload, and when the absolute value of the difference between the detected slope-related value detected by the slope-related value detection unit and the slope-related value of the vehicle in the straight-ahead state obtained and stored in advance, i.e., the reference slope-related value, is greater than a first threshold value, and when the absolute value of the difference between the detected slope-related value and the reference slope-related value converted into a value of the movement of the steering rod is less than a third threshold value, the workload correction unit corrects the corrected workload based on the detected slope-related value.

5. The workload acquisition device according to any one of claims 1 to 4, wherein: The rear wheel steering system includes a lever position detection unit for detecting the position of the steering lever, that is, the displacement from the neutral position. The workload acquisition device includes a movement determination unit. When the absolute value of the difference between the position of the steering rod obtained based on the workload of the actuator detected by the workload detection device when the main switch of the vehicle is switched from on to off, that is, the rod position when off, and the position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, that is, the rod position when on, is greater than a second threshold, the movement determination unit determines that the steering rod was moved by external force during the period when the main switch was off.

6. The workload acquisition device according to any one of claims 1 to 5, wherein: The slope-related value detection unit detects at least one of the following a and b as the slope-related value, wherein: a is the amount of operation of the steering operating member provided on the vehicle from the neutral position, b is the slope of the axis of the camera mounted so as to be able to capture an image of the front of the vehicle, with respect to the traveling direction of the vehicle.

7. A workload acquisition device, comprising: a workload detection device for detecting a workload of an actuator of an onboard device mounted on a vehicle; a first physical quantity detection device for detecting a first physical quantity which is a physical quantity corresponding one-to-one to the workload; as well as a workload correction unit that corrects the workload based on the first physical quantity detected by the first physical quantity detection device, in, In a state where the actuator is controlled based on the workload detected by the workload detection device, when the vehicle travels in a predetermined setting state, the workload correction unit corrects the workload of the actuator based on the value detected by the first physical quantity detection device.

8. The workload acquisition device according to claim 7, wherein: The workload acquisition device includes a second physical quantity detection device different from the first physical quantity detection device, the second physical quantity detection device detects a second physical quantity, the second physical quantity is a physical quantity different from the first physical quantity, and has a one-to-one correspondence with the workload, When the absolute value of the difference between the value obtained by converting the workload detected by the workload detection device into the second physical quantity, i.e., the second conversion value, and the value detected by the second physical quantity detection device, i.e., the second detection value, is less than a fourth threshold, the workload correction unit does not correct the workload based on the second detection value; when it is above the fourth threshold, it corrects the workload based on the second detection value.

9. A steering system, wherein: The steering system comprises: A steering rod is arranged to extend in the width direction of the vehicle and is connected to the wheels; an actuator capable of moving the steering rod in the width direction; A workload detection device for detecting the workload of the actuator; a lever position detection unit that detects the position of the steering lever, that is, the displacement of the steering lever from a neutral position; and A workload correction unit corrects the workload based on the on-time lever position when the absolute value of the difference between the position of the steering rod obtained based on the workload when the main switch of the vehicle is switched from on to off, i.e., the off-time lever position, and the position of the steering rod detected by the lever position detection unit when the main switch is switched from off to on, i.e., the on-time lever position, is greater than a second threshold value.

10. A steering system, wherein: The steering system comprises: A steering rod is arranged to extend in the width direction of the vehicle and is connected to the wheels; an actuator capable of moving the steering rod in the width direction; A workload detection device for detecting the workload of the actuator; a lever position detection unit that detects the position of the steering lever, that is, the displacement of the steering lever from a neutral position; and The movement determination unit determines that the steering rod has been moved in the width direction by an external force while the main switch is off, when an absolute value of a difference between a position of the steering rod obtained based on the workload when a main switch of the vehicle is switched from on to off, i.e., a rod position when off, and a position of the steering rod detected by the rod position detection unit when the main switch is switched from off to on, i.e., a rod position when on, is greater than a second threshold value.

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