Steering control device and steering control method

Abstract

To provide a steering control device and a steering control method that are able to prevent deterioration of operability.SOLUTION: A control device calculates an electric current command value for operating a steering unit, based on an operation of a lever. The control device is configured to execute processing of step 103 of calculating a longitudinal change amount indicating a behavior of a vehicle, processing of steps 104, 106 of calculating a correction operation amount for correcting an operation of the steering unit, based on the longitudinal change amount, and processing of step 105 of reflecting the correction operation amount when calculating a correction inclination angle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a steering control device and a steering control method. [Background technology]

[0002] Conventionally, there has been a so-called steer-by-wire steering device in which the power transmission path between the steering wheel and the steered wheels is separated. The steering device has an operation unit having a steering wheel, and a steering unit that generates a force for steering the steered wheels. The steering wheel is an operation member that is operated by the driver. In recent years, various types of operation members other than the steering wheel have been proposed, taking advantage of the separation of the power transmission path between the steering wheel and the steered wheels. For example, Patent Documents 1 and 2 describe steering devices that use a joystick as an operation member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,086,870 [Patent Document 2] Japanese Patent Application Publication No. 8-34353 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the tilt angle range, which is the operational range of a joystick, is smaller than the rotation angle range, which is the operational range of a steering wheel. This means that the resolution of joystick operation is lower than the resolution of steering wheel operation. In other words, the resolution of joystick operation is lower than the resolution of steering the steered wheels. For this reason, a steering control device that controls a steering device using a joystick as described above controls the joystick operation amount required to steer the steered wheels by the same steering amount so that it is smaller than the steering wheel operation amount.

[0005] The use of a joystick can improve convenience for the operator. However, the change in steering amount relative to the joystick operation amount is larger than the change in steering amount relative to the steering wheel operation amount. For example, even a small movement of the joystick due to a change in vehicle behavior can result in a large change in the steering angle. This can result in a decrease in operability. This problem is not limited to the use of a joystick, but can occur in any steering device in which the resolution of the operation amount of the operating member is lower than the resolution of the steering amount of the steered wheels. [Means for solving the problem]

[0006] A steering control device that can solve the above problems controls a steering device of a vehicle. The steering device has a structure in which power transmission paths between an operation unit having an operation member and a steering unit configured to steer steered wheels are separated, and a resolution of the operation amount of the operation member is lower than a resolution of the steering amount of the steered wheels. The steering control device has a steering control unit that calculates an operation signal for actuating the steering unit based on the operation of the operation member, and the steering control unit is configured to execute a vehicle state quantity calculation process that calculates a vehicle state quantity indicative of the behavior of the vehicle, a correction operation amount calculation process that calculates a correction operation amount for correcting the operation of the operation member based on the vehicle state quantity, and a correction process that reflects the correction operation amount when calculating the operation signal.

[0007] An operation control method that can solve the above problem controls a steering device of a vehicle. The steering device has a structure in which a power transmission path between an operation unit having an operation member and a steering unit configured to steer steered wheels is separated, and a resolution of the operation amount of the operation member is lower than a resolution of the steering amount of the steered wheels. The steering control method includes calculating an operation signal for actuating the steering unit based on the operation of the operation member, and calculating the operation signal includes performing a vehicle state quantity calculation process that calculates a vehicle state quantity indicative of the behavior of the vehicle, a correction operation amount calculation process that calculates a correction operation amount for correcting the operation of the operation member based on the vehicle state quantity, and a correction process that reflects the correction operation amount when calculating the operation signal.

[0008] According to the above configuration and method, the vehicle behavior can be estimated based on the vehicle state quantity. The corrective operation amount can be obtained by estimating the vehicle behavior. For example, the vehicle behavior changes depending on the condition of the road surface on which the vehicle is traveling. Even if the operating member moves due to such a change in the vehicle behavior depending on the condition of the road surface on which the vehicle is traveling, the influence of the change can be reflected in the operation signal as the corrective operation amount. Therefore, control can be performed to suppress deterioration of operability.

[0009] In the steering control device, it is preferable that the correction operation amount calculation process is a process of calculating the correction operation amount corresponding to an amount of change of the operation member with respect to the vehicle state amount. According to the above configuration, it is possible to effectively prevent the steering of the steered wheels regardless of the operator's intention, which would otherwise occur due to movement of the operating member caused by changes in the vehicle's behavior in response to the road surface conditions on which the vehicle is traveling. This is effective in optimizing operability for the vehicle's traveling conditions.

[0010] In the above steering control device, it is preferable that the operating member is a two-axis lever capable of detecting operation in two different directions, and the vehicle state quantity calculation process includes a process of calculating the vehicle state quantity based on the operation amount in a specific direction among the operation amounts of the two-axis lever.

[0011] According to the above configuration, by using a two-axis lever as the operating member, it is possible to suitably estimate the vehicle behavior without using any vehicle information other than the amount of operation in one specific direction. This simplifies the configuration for detecting situations in which the lever moves due to changes in the vehicle behavior depending on the road conditions. This is effective in optimizing operability for the vehicle's driving state.

[0012] In the above steering control device, it is preferable that the vehicle state quantity calculation process includes a process of calculating the vehicle state quantity based on vehicle information other than the operation amount of the operating member, and the vehicle information is a sensor value detected by a sensor mounted on the vehicle.

[0013] According to the above configuration, the vehicle behavior can be suitably estimated regardless of the configuration of the operating member. This makes it possible to suitably detect situations in which the lever moves due to changes in the vehicle behavior depending on the road conditions. This is effective in optimizing operability for the vehicle's driving state.

[0014] In the above steering control device, it is preferable that the steering control section includes an operation amount calculation section which calculates an operation amount of the operation member based on operation of the operation member, a target steering operation amount calculation section which calculates a target steering operation amount which is a target value of the steering operation amount based on the operation amount of the operation member, and an operation signal calculation section which calculates the operation signal based on the target steering operation amount, the steering operation amount being information obtained from the steering unit, the operation amount calculation section including the vehicle state amount calculation processing, the corrected operation amount calculation processing and the correction processing, and the correction processing is processing which reflects the corrected operation amount in the operation amount of the operation member.

[0015] According to the above configuration, even if the operating member moves due to a change in vehicle behavior, it is possible to prevent such movement from being reflected in the operation of the steering unit. This makes it possible to preferably prevent the steered wheels from being steered regardless of the operator's intention, which would be caused by the operating member moving due to a change in vehicle behavior in response to the road conditions on which the vehicle is traveling. This is effective in optimizing operability according to the vehicle's traveling conditions. [Effects of the Invention]

[0016] According to the present invention, it is possible to suppress a decrease in operability. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a steering device of a first embodiment and a control device that controls the steering device. [Figure 2] FIG. 2 is a block diagram of the control device of FIG. [Figure 3] 3 is a flowchart showing an example of a processing procedure for calculating corrected left and right tilt angles by a lever tilt angle calculation unit shown in FIG. 2 according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing an example of a correction gain map provided in the control device of FIG. 1 according to the first embodiment. [Figure 5] In the first embodiment, (a) is a diagram showing how the left and right inclination angles change when the vehicle travels on a smooth road surface, and (b) is a diagram showing how the left and right inclination angles change when the vehicle travels on a rough road surface. [Figure 6] In the first embodiment, (a) is a diagram showing how the inclination angle changes before and after when the vehicle runs on a smooth road surface, and (b) is a diagram showing how the inclination angle changes before and after when the vehicle runs on a rough road surface. [Figure 7] 7A and 7B are diagrams showing how the left and right tilt angles change when the amount of correction operation is reflected in FIG. 6B. [Figure 8]10 is a flowchart illustrating an example of a processing procedure for calculating corrected left and right tilt angles by a lever tilt angle calculation unit in FIG. 2 according to the second embodiment. [Figure 9] 11 is a flowchart illustrating an example of a processing procedure for calculating corrected left and right tilt angles by a lever tilt angle calculation unit in FIG. 2 according to the third embodiment. [Figure 10] FIG. 10 is a block diagram of the control device of FIG. 1 according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Embodiment 1> A first embodiment of the steering control device will be described below with reference to the drawings. <Overall structure> As shown in FIG. 1, steering device 1 is a steer-by-wire type steering device for a vehicle. Steering device 1 has an operation unit 2, a steering unit 3, and a control device 4. Operation unit 2 is a mechanical part that is operated by the driver when changing the direction of travel of the vehicle. Steering unit 3 is a mechanical part for steering steered wheels 5 of the vehicle. The power transmission paths between operation unit 2 and steering unit 3 are mechanically separated. Control device 4 controls the operation of steering unit 3 according to the operation state of operation unit 2.

[0019] The operation unit 2 has a base 2A and a lever 2B. The base 2A supports the lever 2B so that it can tilt. The lever 2B is an operating member operated by an operator. The operator includes the driver of the vehicle. The lever 2B is, for example, a lever that can tilt in all directions. The lever 2B is a two-axis lever that can detect tilting, which is operation in two different directions. The two different directions are an X-axis direction (indicated as "X" in FIG. 1) and a Y-axis direction (indicated as "Y" in FIG. 1) that are perpendicular to each other. The X-axis direction is the left-right direction that coincides with the width direction that is perpendicular to the traveling direction of the vehicle. The Y-axis direction is the front-rear direction that coincides with the traveling direction of the vehicle. When no operating force is applied to the lever 2B, the lever 2B is maintained in a neutral position. The neutral position is a position of the lever 2B that corresponds to the straight-ahead state of the vehicle. In this embodiment, the neutral position corresponds to the intersection of the midpoints of the tilting range of the lever 2B in each of the X-axis and Y-axis directions, i.e., the origin. When the operator turns the vehicle left relative to the traveling direction, the operator tilts the lever 2B to the left, which is one side of the X-axis direction. When the operator turns the vehicle right relative to the traveling direction, the operator tilts the lever 2B to the right, which is one side of the X-axis direction. When the operating force applied to the lever 2B is released, the lever 2B automatically returns to the neutral position, which is the original position. In this embodiment, the lever 2B is an example of an operating member.

[0020] The operation unit 2 has a tilt angle sensor 2C. The tilt angle sensor 2C detects the tilt angle θlr(X) and tilt angle θlr(Y) of the lever 2B. The tilt angle sensor 2C generates an electrical signal corresponding to the tilt angles θlr(X) and (Y) of the lever 2B. The tilt angle θlr(X) is the tilt angle in the X-axis direction relative to the neutral position of the lever 2B and indicates the amount of left and right operation of the lever 2B. When the lever 2B is tilted to the right relative to the neutral position, the tilt angle θlr(X) is a positive value. When the lever 2B is tilted to the left relative to the neutral position, the tilt angle θlr(X) is a negative value. The tilt angle θlr(Y) is the tilt angle in the Y-axis direction relative to the neutral position of the lever 2B and indicates the amount of forward and backward operation of the lever 2B. When the lever 2B is tilted forward relative to the neutral position, the tilt angle θlr(Y) is a positive value. When the lever 2B is tilted rearward relative to the neutral position, the tilt angle θlr(Y) takes a negative value. However, the correspondence between the tilt direction of the lever 2B and the positive or negative sign may be reversed.

[0021] The operation unit 2 is connected to the control device 4, for example, via a harness, which is an electric wire. The inclination angles θlr(X), (Y) detected by the inclination angle sensor 2C are transmitted to the control device 4, for example, via the harness. Note that the operation unit 2 may transmit the inclination angles θlr(X), (Y) to the control device 4 via wireless communication. In this case, a communication circuit is provided in the operation unit 2 and the control device 4. The communication circuit includes a transmitting circuit that transmits a wireless signal and a receiving circuit that receives the wireless signal.

[0022] The steering unit 3 has a pinion shaft 21, a steering shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. The housing 23 also accommodates the steering shaft 22 so that it can reciprocate. The pinion shaft 21 is arranged to intersect with the steering shaft 22. A rack-and-pinion mechanism is formed by the engagement of pinion teeth 21a of the pinion shaft 21 with rack teeth 22a of the steering shaft 22. Tie rods 25 are connected to both ends of the steering shaft 22 via rack ends 24 made up of ball joints. The ends of the tie rods 25 are connected to knuckles (not shown) to which the steered wheels 5 are assembled.

[0023] Furthermore, steering unit 3 includes steering motor 31, transmission mechanism 32, and conversion mechanism 33. Steering motor 31 is a source of steering force applied to steering shaft 22. The steering force is a force for steering steered wheels 5. Steering motor 31 is, for example, a three-phase brushless motor. Transmission mechanism 32 is, for example, a belt transmission mechanism. Transmission mechanism 32 transmits the rotation of steering motor 31 to conversion mechanism 33. Conversion mechanism 33 is, for example, a ball screw mechanism. Conversion mechanism 33 converts the rotation transmitted via transmission mechanism 32 into axial movement of steered shaft 22.

[0024] The steered angle θw of the steered wheels 5 is changed by the axial movement of the steered shaft 22. Pinion teeth 21a of the pinion shaft 21 mesh with rack teeth 22a of the steered shaft 22. Therefore, the pinion shaft 21 rotates in conjunction with the movement of the steered shaft 22. The pinion shaft 21 is a shaft that rotates in conjunction with the steering operation of the steered wheels 5. The steered wheels 5 are steered left or right relative to the traveling direction of the vehicle, based on a rack neutral position, which is a position corresponding to the vehicle's straight-ahead traveling state. The sign of the steered angle θw is, for example, negative in the left steering direction based on the rack neutral position, and positive in the right steering direction.

[0025] The control device 4 is an example of a steering control device that controls the steering device 1. More specifically, the control device 4 controls the operation of the steering motor 31. The control device 4 has a processing circuit that includes any one of the following three configurations (A1), (A2), and (A3).

[0026] (A1) One or more processors that operate according to a computer program that is software. The processor includes a CPU (Central Processing Unit) and memory. (A2) One or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that execute at least some of the various processes. The ASIC includes a CPU and a memory.

[0027] (A3) A hardware circuit that combines configurations A1 and A2. The memory is a computer-readable medium that stores a program that describes processes or instructions for the computer. In this embodiment, the computer is a CPU. The memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU executes various controls by executing the program stored in the memory at a predetermined calculation cycle.

[0028] Control device 4 refers to the detection results of sensors mounted on the vehicle. The sensors include a vehicle speed sensor 41 and a rotation angle sensor 42. Control device 4 refers to vehicle speed V detected by vehicle speed sensor 41. Control device 4 refers to rotation angle θb of steering motor 31 detected by rotation angle sensor 42. Control device 4 refers to the operation state of operation unit 2 and the detection results of various sensors, and controls the operation of steering motor 31. Control device 4 controls the supply of power to steering motor 31 so that steered wheels 5 are steered in accordance with the operation state of operation unit 2. In this embodiment, vehicle speed V is an example of a driving parameter that indicates the driving state of the vehicle.

[0029] When lever 2B is in the neutral position, control device 4 controls steering motor 31 so that steered wheels 5 are maintained in the rack neutral position. When lever 2B is tilted to the left, control device 4 controls steering motor 31 so that steered wheels 5 are steered to the left relative to the traveling direction of the vehicle. When lever 2B is tilted to the right, control device 4 controls steering motor 31 so that steered wheels 5 are steered to the right relative to the traveling direction of the vehicle. In this embodiment, when lever 2B is tilted to the left or operated to the left, it means tilting to the left in the X-axis direction. When lever 2B is tilted to the right or operated to the right, it means tilting to the right in the X-axis direction. Furthermore, operating lever 2B left and right means tilting to the left and right in the X-axis direction. Similarly, operating lever 2B up and down means tilting to the up and down in the Y-axis direction.

[0030] In this embodiment, the tilt angle range, which is the left and right operation range of lever 2B, is smaller than the rotation angle range, which is the operation range of the steering wheel. This means that the resolution of the left and right operation of lever 2B is lower than the resolution of the operation of the steering wheel. In other words, the resolution of the operation of lever 2B is lower than the resolution of the steering of steered wheels 5. For this reason, the control device 4, which controls the steering device 1 using lever 2B as in this embodiment, controls so that the left and right operation amount of lever 2B required to steer steered wheels 5 by the same steering amount is smaller than the operation amount of the steering wheel.

[0031] <Configuration of control device 4> Next, the configuration of the control device 4 will be described. 2, the control device 4 has a pinion angle calculation unit 61, a correction inclination angle calculation unit 62, a target pinion angle calculation unit 63, a pinion angle feedback control unit ("pinion angle F / B control unit" in the figure) 64, and an energization control unit 65. In the present embodiment, the control device 4 is an example of a steering control unit.

[0032] Pinion angle calculation unit 61 receives rotation angle θb as an input and calculates pinion angle θp. Pinion angle calculation unit 61 includes a process for counting the number of rotations of steering motor 31 from the rack neutral position and converting the counted number of rotations into an integrated angle that includes a range exceeding 360°. Pinion angle calculation unit 61 also includes a process for multiplying the converted integrated angle by a conversion coefficient to calculate pinion angle θp, which is the actual rotation angle of pinion shaft 21. The conversion coefficient is a value obtained based on the reduction ratio of power transmission mechanism 32, the lead of conversion mechanism 33, and the rotational speed ratio of the rack-and-pinion mechanism. Pinion angle θp is positive when the angle is to the right of the rack neutral position, which is the straight-ahead steering position, and negative when the angle is to the left. Steering motor 31 and pinion shaft 21 are linked via power transmission mechanism 32, conversion mechanism 33, and steering shaft 22. Therefore, there is a correlation between rotation angle θb of steering motor 31 and pinion angle θp. Using this correlation, pinion angle θp can be found from rotation angle θb of steering motor 31. Pinion shaft 21 meshes with steered shaft 22. Therefore, there is also a correlation between pinion angle θp and the amount of movement of steered shaft 22. In other words, pinion angle θp is a value that reflects the turning angle θw of steered wheels 5. Rotation angle sensor 42 is also a sensor for detecting pinion angle θp.

[0033] The correction inclination angle calculation unit 62 is a process that calculates the correction inclination angle θlr using the inclination angles θlr(X), (Y) and the pinion angle θp as inputs. The correction inclination angle θlr is the amount of operation of the lever 2B that is used to reflect the steering of the steered wheels 5, i.e., the amount of left and right operation of the lever 2B. In this embodiment, the correction inclination angle calculation unit 62 is an example of an operation amount calculation unit.

[0034] Target pinion angle calculation unit 63 is a process that calculates target pinion angle θp*, which is the target steering operation amount, using corrected inclination angle θlr and vehicle speed V as input. Target pinion angle θp* is a target value for pinion angle θp, which is the steering operation amount. Target pinion angle θp* corresponds to the target rotation angle of a shaft that rotates in conjunction with the operation, which is the turning angle θw of steered wheels 5. In the present embodiment, target pinion angle calculation unit 63 is an example of a target steering operation amount calculation unit.

[0035] Pinion angle feedback control unit 64 is a process that calculates a turning torque command value Tp* so as to control pinion angle θp to final target pinion angle θp* by feedback control. Turning torque command value Tp* is a command value for the torque of turning motor 31. Note that pinion angle feedback control unit 64 includes a process that calculates pinion angle deviation Δθp obtained by subtracting pinion angle θp from final target pinion angle θp*. Pinion angle feedback control unit 64 also includes a process that calculates turning torque command value Tp* by executing proportional, integral, and derivative operations on pinion angle deviation Δθp. In other words, turning torque command value Tp* is the sum of the output value of a proportional element, the output value of an integral element, and the output value of a derivative element that have pinion angle deviation Δθp as an input.

[0036] Energization control unit 65 processes to supply electric power to steering motor 31 according to steering torque command value Tp*. More specifically, energization control unit 65 includes a process of calculating a current command value, which is an operation signal for steering motor 31, using steering torque command value Tp*, rotation angle θb, and current Ib as inputs. Energization control unit 65 includes a process of detecting the value of current Ib generated in the power supply path to steering motor 31, using current sensor 66 provided in the power supply path. The value of current Ib is the value of the current supplied to steering motor 31. Energization control unit 65 includes a process of determining the deviation between the current command value and the value of current Ib, and controlling the power supply to steering motor 31 so as to eliminate this deviation. As a result, steering motor 31 generates torque according to steering torque command value Tp*. In the present embodiment, energization control unit 65 is an example of an operation signal calculation unit.

[0037] <Processing procedure for calculating the correction tilt angle> Next, an example of a processing procedure in which the control device 4 calculates the corrected inclination angle θlr through the corrected inclination angle calculation unit 62 will be described with reference to the flowchart shown in FIG.

[0038] As shown in the figure, the control device 4 inputs the inclination angles θlr(X), (Y) (step 101) and the pinion angle θp (step 102). Next, the control device 4 determines whether the absolute value of the longitudinal change amount Δθlr(Y) is greater than the change threshold value Δθth (step 103). In step 103, the control device 4 calculates the longitudinal change amount Δθlr(Y), which is the amount of change in the inclination angle θlr(Y) input in step 101 over a predetermined detection period. The longitudinal change amount Δθlr(Y) is, for example, a value obtained as the maximum amount of change over a single detection period. If the longitudinal change amount Δθlr(Y) is a value other than zero, it indicates that the lever 2B has been tilted forward or backward. Operation of the lever 2B basically involves left and right operation.

[0039] However, the left and right operation of lever 2B may also move up and down due to changes in the vehicle's behavior. The vehicle's behavior changes depending on the condition of the road surface on which it is traveling. For example, when a vehicle travels on a rough road surface with an uneven surface, changes in the vehicle's behavior appear as an unintended forward and backward operation of lever 2B by the driver. When such unintended forward and backward operation of lever 2B appears, it can be considered that this also appears as an unintended left and right operation of lever 2B by the driver.

[0040] In this embodiment, the process of step 103 is a process of detecting the behavior of the vehicle while traveling on a rough road surface by estimating the behavior of the vehicle. That is, the process of step 103 is a process of detecting the left / right operation of the lever 2B unintentionally by the driver. Note that, if the absolute value of the longitudinal change amount Δθlr(Y) is greater than the change threshold value Δθth, the control device 4 determines that the lever 2B has moved left / right due to a change in the behavior of the vehicle while traveling on a rough road surface. Also, if the absolute value of the longitudinal change amount Δθlr(Y) is equal to or less than the change threshold value Δθth, the control device 4 determines that the lever 2B has not moved left / right due to a change in the behavior of the vehicle while traveling on a rough road surface. The change threshold value Δθth is a value within a range that can determine that the behavior of the vehicle while traveling on a rough road surface is the behavior of the vehicle. In this embodiment, the process of step 103 is an example of a vehicle state quantity calculation process. Also, the longitudinal change amount Δθlr(Y) is an example of a vehicle state quantity that indicates the behavior of the vehicle.

[0041] Next, if the absolute value of the longitudinal change amount Δθlr(Y) is greater than the change threshold value Δθth (step 103: YES), the control device 4 calculates the corrective operation amount θc (step 104). In step 104, the control device 4 calculates the corrective operation amount θc by multiplying the longitudinal change amount Δθlr(Y) calculated in step 103 by a correction gain K. The process of calculating the corrective operation amount θc in step 104 is a process of detecting the left and right operation amounts of the lever 2B that appear as unintended operations by the driver. In this embodiment, the process of step 104 is an example of a corrective operation amount calculation process.

[0042] The processing of step 104 can be realized, for example, by having the CPU calculate the correction gain K through map calculation using a correction gain map M1, which is map data stored in advance in the memory of the control device 4. This correction gain map M1 is data that uses the pinion angle θp as an input variable and the correction gain K as an output variable.

[0043] Map data is a set of data consisting of discrete values ​​of input variables and values ​​of output variables corresponding to each of the input variable values. Furthermore, the map calculation may be a process in which, when the value of an input variable matches one of the input variable values ​​in the map data, the value of the corresponding output variable in the map data is used as the calculation result. Furthermore, when the value of an input variable does not match any of the input variable values ​​in the map data, the map calculation may be a process in which the value obtained by interpolating the values ​​of multiple output variables included in the map data is used as the calculation result. Alternatively, when the value of an input variable does not match any of the input variable values ​​in the map data, the map calculation may be a process in which the value of the output variable in the map data that corresponds to the closest value among the multiple output variable values ​​included in the map data is used as the calculation result.

[0044] As shown in FIG. 4, the correction gain map M1 used in step 104 has the following characteristics. That is, for example, the value of the correction gain K is constant when the value of the pinion angle θp is equal to or less than the first threshold value θp1 and equal to or greater than the second threshold value θp2. However, the value of the correction gain K differs between when the value of the pinion angle θp is equal to or less than the first threshold value θp1 and when the value of the pinion angle θp is equal to or greater than the second threshold value θp2. Furthermore, when the value of the correction gain K is greater than the first threshold value θp1 and less than the second threshold value θp2, the value of the correction gain K monotonically decreases according to the value of the pinion angle θp. This is because it is considered that the impact of vehicle sway on operation is greater when the pinion angle θp is close to the rack neutral position equal to or less than the first threshold value θp1 than when it is far from the rack neutral position equal to or greater than the second threshold value. Note that when the value of the pinion angle θp is close to the rack neutral position equal to or less than the first threshold value θp1, it can be assumed that the vehicle speed V is high, for example, when the vehicle is traveling at a high speed. Furthermore, when the value of the pinion angle θp is away from the rack neutral position by a distance equal to or greater than the second threshold value, it can be assumed that the vehicle speed V is low, for example, that the vehicle is traveling at a low speed.

[0045] Next, the control device 4 calculates the corrected inclination angle θlr (step 105). In step 105, the control device 4 calculates the corrected inclination angle θlr by subtracting the corrective operation amount θc calculated in step 104 from the inclination angle θlr(X) input in step 101, as shown in the following equation (1).

[0046] θlr=θlr(X)-θc …(1) Here, "θc" is "K·Δθlr(Y)", where "·" indicates multiplication. When detecting an unintended left / right operation of the lever 2B by the driver, the control device 4 subtracts the correction operation amount θc based on the above formula (1) to reflect the unintended left / right operation of the lever 2B so as to eliminate the unintended left / right operation of the lever 2B by the driver. As a result, the control device 4 reflects the correction operation amount θc in the current command value calculated by the corrected inclination angle θlr, i.e., the operation signal. In this embodiment, the processing of step 105 is an example of a correction reflection processing.

[0047] On the other hand, if the absolute value of the longitudinal change amount Δθlr(Y) is equal to or less than the change threshold value Δθth (step 103: NO), the control device 4 calculates a value of zero as the correction operation amount θc (step 106). In step 106, the control device 4 calculates a value of zero as the correction operation amount θc regardless of the longitudinal change amount Δθlr calculated in step 103. In this embodiment, the value of zero is a value within a range that does not affect the target pinion angle θp* when reflected in the left and right operation amounts of the lever 2B. Note that the processing of step 106 can be implemented, for example, by calculating a value of zero as the correction gain K. In this case, the control device 4 reflects the left and right operation of the lever 2B by the driver as is, based on the fact that no unintended operation of the lever 2B by the driver is detected. In this embodiment, the processing of step 106 is an example of a correction reflection processing.

[0048] This completes the process of calculating the correction inclination angle θlr. <Processing procedure for calculating target pinion angle> As shown in FIG. 2, the target pinion angle calculation unit 63 includes an inclination angle conversion calculation unit 71, a vehicle speed gain calculation unit 72, and a multiplier 73.

[0049] The inclination angle conversion calculation unit 71 is a process that calculates the target pinion angle base value θpb* using the corrected inclination angle θlr as an input. The inclination angle conversion calculation unit 71 can be realized, for example, by having the CPU calculate the target pinion angle base value θpb* through map calculations using a conversion map M2, which is map data pre-stored in the memory of the control device 4. This conversion map M2 is data that uses the corrected inclination angle θlr as an input variable and the target pinion angle base value θpb* as an output variable.

[0050] As shown in FIG. 2, the conversion map M2 has the following characteristics. That is, the greater the absolute value of the corrected inclination angle θlr, the greater the absolute value of the target pinion angle base value θpb*. The absolute value of the target pinion angle base value θpb* changes, for example, linearly with respect to changes in the absolute value of the corrected inclination angle θlr. Furthermore, when the corrected inclination angle θlr is a positive value, the target pinion angle base value θpb* is calculated as a positive value. Furthermore, when the corrected inclination angle θlr is a negative value, the target pinion angle base value θpb* is calculated as a negative value.

[0051] The vehicle speed gain calculation unit 72 is a process that calculates the vehicle speed gain G using the vehicle speed V as an input. The vehicle speed gain calculation unit 72 can be realized, for example, by having the CPU calculate the vehicle speed gain G through map calculation using a vehicle speed gain map M3 that is map data pre-stored in the memory of the control device 4. This vehicle speed gain map M3 is data that uses the vehicle speed V as an input variable and the vehicle speed gain G as an output variable.

[0052] 2, the vehicle speed gain map M3 has the following characteristics: The value of the vehicle speed gain G is constant when the value of the vehicle speed V is equal to or less than the threshold value Vth. When the value of the vehicle speed V is greater than the threshold value Vth, the value of the vehicle speed gain G decreases as the value of the vehicle speed V increases. However, the value of the vehicle speed gain G changes, for example, nonlinearly with changes in the value of the vehicle speed V.

[0053] The multiplier 73 multiplies the target pinion angle base value θpb* by the vehicle speed gain G to calculate the target pinion angle θp*. <Actions and Effects of the First Embodiment> For example, Figures 5(a) and 5(b) show how the inclination angle θlr(X) changes over time when the lever 2B is tilted leftward from the neutral position and then maintained in that tilted position. Figures 6(a) and 6(b) show how the inclination angle θlr(Y) changes over time under the same conditions as Figures 5(a) and 5(b).

[0054] As shown in Figure 5(a), when the vehicle is traveling on a leveled road surface, the inclination angle θlr(X) changes linearly, without any nonlinear changes. In this case, the inclination angle θlr(X) remains zero while the lever 2B is in the neutral position, i.e., while the vehicle is traveling straight. The inclination angle θlr(X) increases to the left as the lever 2B is tilted left from the neutral position and the steered wheels 5 are turned left, i.e., while the vehicle is turning left.

[0055] On the other hand, as shown in FIG. 5(b), when the vehicle is traveling on a rough road surface with an uneven surface, the inclination angle θlr(X) changes nonlinearly. In this case, the inclination angle θlr(X) fluctuates left and right so as to cross zero during period t1 when the lever 2B is in the neutral position, i.e., while the vehicle is traveling straight. The inclination angle θlr(X) fluctuates left and right as the value to the left increases during period t2 when the lever 2B is tilted left from the neutral position and the steered wheels 5 are turned left, i.e., while the vehicle is turning left. Note that the change in the inclination angle θlr(X) changes linearly except when the vehicle is traveling on a rough road surface.

[0056] As shown in FIG. 6(a), when the vehicle is traveling on a level road surface, the inclination angle θlr(Y) changes linearly with a relatively small value. In this case, the inclination angle θlr(Y) remains zero while the lever 2B is in the neutral position, i.e., while the vehicle is traveling straight. When the lever 2B is tilted left from the neutral position and the steered wheels 5 are turned to the left, i.e., while the vehicle is turning left, the inclination angle θlr(Y) becomes slightly larger, for example, upward out of the up and down directions. This change is due to the driver's characteristics and habits when operating the lever 2B left or right.

[0057] On the other hand, as shown in FIG. 6(b), when the vehicle is traveling on a rough road surface, the inclination angle θlr(Y) changes nonlinearly. In this case, the inclination angle θlr(Y) fluctuates up and down, crossing zero, during period t1 when the lever 2B is in the neutral position, i.e., while the vehicle is traveling straight. The inclination angle θlr(X) fluctuates up and down, with the upward value becoming slightly larger, during period t2 when the lever 2B is tilted left from the neutral position and the steered wheels 5 are turned left, i.e., while the vehicle is turning left. Note that the change in the inclination angle θlr(Y) is linear except when the vehicle is traveling on a rough road surface.

[0058] In response to this, the corrected inclination angle calculation unit 62 performs the process of step 103, which estimates the behavior of the vehicle while traveling on a rough road surface based on the inclination angle θlr(Y) to detect the behavior of the vehicle while traveling on a rough road surface, i.e., detects unintended left / right operation of the lever 2B by the driver. The process of step 103 detects changes in the inclination angle θlr(Y) in FIG. 6(b) that are equal to or greater than the change threshold value Δθth. For example, if the amount of change in the nonlinear change in the inclination angle θlr(Y) in FIG. 6(b) is equal to or greater than the change threshold value Δθth, the behavior of the vehicle while traveling on a rough road surface is detected during the corresponding periods t1 and t2.

[0059] Furthermore, the correction inclination angle calculation unit 62 executes the process of step 104 to calculate the correction operation amount θc based on the longitudinal change amount Δθlr(Y). In the process of step 104, the correction operation amount θc is calculated as the left and right operation amounts of the lever 2B unintentionally performed by the driver during periods t1 and t2 in FIG. 6(b).

[0060] Furthermore, the corrected inclination angle calculation unit 62 executes the process of step 105, which calculates the corrected inclination angle θlr by reflecting the corrected operation amount θc on the inclination angle θlr(X). The process of step 105 reflects the corrected operation amount θc so as to remove the left and right operation amounts of the lever 2B unintended by the driver.

[0061] For example, as shown in Fig. 7, when the vehicle is traveling on a rough road surface, the nonlinear changes in the correction inclination angle θlr during periods t1 and t2 are removed. In this case, the change in the correction inclination angle θlr is corrected from the state when the vehicle is traveling on a rough road surface to the state when the vehicle is traveling on a smooth road surface.

[0062] As described above, even if the lever 2B moves due to a change in the behavior of the vehicle while traveling on a rough road, the effect of this movement can be reflected in the target pinion angle θp* as the correction operation amount θc. Therefore, control can be performed to prevent a decrease in operability.

[0063] According to the present embodiment described above, the following actions and effects can be further obtained. (1-1) The processing of step 104 is processing for calculating a correction operation amount θc corresponding to the left / right operation amount of the lever 2B with respect to the longitudinal change amount Δθlr(Y). This makes it possible to suitably prevent the steered wheels 5 from being steered regardless of the driver's intention, which would otherwise occur if the lever 2B were to move due to a change in the behavior of the vehicle depending on the condition of the road surface on which the vehicle is traveling. This is effective in optimizing operability for the vehicle's traveling state.

[0064] (1-2) By adopting a two-axis lever as the lever 2B, it is possible to appropriately estimate the vehicle behavior without using any vehicle information other than the tilt angle θlr(Y), which is the amount of operation in the up and down directions. This simplifies the configuration for detecting situations in which the lever 2B moves due to changes in the vehicle behavior depending on the road conditions. This is effective in optimizing operability for the vehicle's driving state.

[0065] (1-3) The control device 4 includes a correction inclination angle calculation unit 62, a target pinion angle calculation unit 63, and an energization control unit 65. The correction inclination angle calculation unit 62 includes the processes of step 103, which is a vehicle state quantity calculation process, step 104, which is a correction operation quantity calculation process, and step 105, which is a correction process. Step 105 is a process of reflecting the correction operation quantity θc in the inclination angle θlr(X) of the lever 2B. In this case, even if the lever 2B moves due to a change in the vehicle behavior, it is possible to prevent such movement from being reflected in the operation of the steering unit 3. This makes it possible to preferably prevent the steered wheels 5 from being turned regardless of the operator's intention, which would be caused by movement of the lever 2B due to a change in the vehicle behavior in response to the road surface conditions on which the vehicle is traveling. This is effective in optimizing operability for the vehicle's traveling state.

[0066] <Second embodiment> Next, a second embodiment of the steering control device will be described. This embodiment basically has the same configuration as the first embodiment. Therefore, detailed descriptions of the same members and configurations as the first embodiment will be omitted. This embodiment differs from the first embodiment in the processing procedure for calculating the correction operation amount θc.

[0067] As indicated by the two-dot chain line in FIG. 1 , the control device 4 according to this embodiment refers to the detection results of the gyro sensor 43 mounted on the vehicle. The gyro sensor 43 detects a roll rate Rr, which is the amount of change in the roll angle generated in the vehicle, as a sensor value. For example, the gyro sensor 43 has one or more detection axes. In this embodiment, the roll rate Rr is an example of vehicle information. Note that the control device 4 may refer to the detection results of an acceleration sensor instead of the gyro sensor 43.

[0068] <Processing procedure for calculating the correction tilt angle> Next, an example of a processing procedure in which the control device 4 calculates the corrected inclination angle θlr through the corrected inclination angle calculation unit 62 will be described with reference to the flowchart shown in FIG.

[0069] As shown in the figure, the control device 4 inputs the inclination angle θlr(X) (step 201) and the pinion angle θp (step 202). Next, the control device 4 inputs the roll rate Rr (step 203) and determines whether the absolute value of the roll rate Rr is greater than a roll rate threshold Rrth (step 204). The behavior of the vehicle changes depending on the condition of the road surface on which the vehicle is traveling. For example, when the vehicle is traveling on a rough road surface, the change in the behavior of the vehicle appears as a large change in the roll rate Rr. When such a large change in the roll rate Rr appears, it can be considered that it also appears as an unintended left / right operation of the lever 2B by the driver.

[0070] In this embodiment, the processing of step 204 is processing to detect the behavior of the vehicle while traveling on a rough road surface by estimating the behavior of the vehicle. That is, the processing of step 204 is processing to detect the left / right operation of the lever 2B unintentionally by the driver. Note that, if the absolute value of the roll rate Rr is greater than the roll rate threshold Rrth, the control device 4 determines that the lever 2B has moved both left and right due to a change in the behavior of the vehicle while traveling on a rough road surface. Also, if the absolute value of the roll rate Rr is equal to or less than the roll rate threshold Rrth, the control device 4 determines that the lever 2B has not moved left or right due to a change in the behavior of the vehicle while traveling on a rough road surface. The roll rate threshold Rrth is a value within a range that can determine that the behavior of the vehicle while traveling on a rough road surface is occurring. In this embodiment, the processing of step 204 is an example of a vehicle state quantity calculation processing. Also, the roll rate Rr is an example of a vehicle state quantity that indicates the behavior of the vehicle.

[0071] Next, if the absolute value of the roll rate Rr is greater than the roll rate threshold Rrth (step 204: YES), the control device 4 calculates the corrective operation amount θc (step 205). In step 205, the control device 4 calculates the corrective operation amount θc by multiplying the roll rate Rr input in step 203 by a correction gain K. The process of calculating the corrective operation amount θc in step 205 is a process of detecting the left and right operation amounts of the lever 2B that appear as an operation unintended by the driver. In this embodiment, the process of step 205 is an example of a process of calculating the corrective operation amount.

[0072] The processing of step 205 can be realized, for example, by using a correction gain map M1 to calculate the correction gain K through map calculations by the CPU, similar to step 104 above. This correction gain map M1 is data that uses the pinion angle θp as an input variable and the correction gain K as an output variable. The correction gain K in this embodiment is calculated in the same manner as step 104 above, except that it serves to change the dimension of the roll rate Rr into the dimension of the inclination angle θlr(X) of the lever 2B.

[0073] Next, the control device 4 calculates the corrected inclination angle θlr (step 206). In step 206, the control device 4 calculates the corrected inclination angle θlr by adding the corrective operation amount θc calculated in step 205 to the inclination angle θlr(X) input in step 201, as shown in the following equation (2).

[0074] θlr=θlr(X)+θc …(2) Here, "θc" is "K·Rr", where "·" indicates multiplication. When the control device 4 detects an unintended left / right operation of the lever 2B by the driver, the control device 4 adds the correction operation amount θc based on the above equation (2) to reflect the unintended left / right operation of the lever 2B by the driver so as to cancel out the unintended left / right operation of the lever 2B. This is because the roll rate Rr appears as a change in the opposite direction to the sway of the vehicle. In other words, the roll rate Rr appears as a change in the opposite direction to the unintended left / right operation of the lever 2B by the driver. Note that when a negative value is set as the correction gain K, the correction operation amount θc may be subtracted, as in the above equation (1). In this embodiment, the processing of step 206 is an example of a correction reflection processing.

[0075] On the other hand, if the absolute value of the roll rate Rr is equal to or less than the roll rate threshold value Rrth (step 204: NO), the control device 4 calculates a value of zero as the corrective manipulated variable θc (step 207), in the same manner as in step 106. In this embodiment, the processing of step 207 is an example of a correction reflection processing.

[0076] This completes the process of calculating the correction inclination angle θlr. According to the second embodiment described above, the same actions and effects as those of the first embodiment can be obtained, and also the same effects as those of (1-3) of the first embodiment can be obtained. Furthermore, according to the second embodiment, the following actions and effects can be further obtained.

[0077] (2-1) The processing in step 205 is processing for calculating a correction operation amount θc corresponding to the left / right operation amount of the lever 2B relative to the roll rate Rr. This makes it possible to suitably prevent the steered wheels 5 from being steered regardless of the driver's intention, which would otherwise occur if the lever 2B were to move due to a change in the behavior of the vehicle depending on the condition of the road surface on which the vehicle is traveling. This is effective in optimizing operability for the vehicle's traveling state.

[0078] (2-2) The process of step 204 is a process for estimating vehicle behavior without using information about the operation of lever 2B. In this case, vehicle behavior can be suitably estimated regardless of the configuration of lever 2B. This makes it possible to suitably detect situations in which lever 2B moves due to changes in vehicle behavior depending on the road conditions. This is effective in optimizing operability for the vehicle's driving state.

[0079] (2-3) According to this embodiment, the lever 2B may be a single-axis lever capable of detecting tilting, which is an operation in one direction. The one direction is the X-axis direction. In other words, the lever 2B can suitably estimate the behavior of the vehicle even if it is not a two-axis lever. This allows for a wider range of design options for the operation unit 2. Therefore, the versatility of the operation unit 2, i.e., the steering device 1, can be improved.

[0080] <Third embodiment> Next, a third embodiment of the steering control device will be described. This embodiment basically has the same configuration as the second embodiment. Therefore, detailed descriptions of the same members and configurations as the second embodiment will be omitted. This embodiment differs from the second embodiment in the processing of step 204 above.

[0081] As shown in FIG. 9, instead of the processing of step 204, the control device 4 according to this embodiment determines whether the absolute value of the roll angular acceleration ARr is greater than the roll angular acceleration threshold value ARrth (step 208). In step 208, the control device 4 calculates the first-order time differential value of the roll rate Rr as the roll angular acceleration ARr. The behavior of the vehicle changes depending on the condition of the road surface on which the vehicle is traveling. For example, when the vehicle is traveling on a rough road surface, the change in the behavior of the vehicle appears as a large change in the roll angular acceleration ARr. When such a large change in the roll angular acceleration ARr appears, it can be considered that it also appears as an unintended left / right operation of the lever 2B by the driver.

[0082] In this embodiment, the processing of step 208 is processing to detect the behavior of the vehicle while traveling on a rough road surface by estimating the behavior of the vehicle. That is, the processing of step 208 is processing to detect the left / right operation of the lever 2B unintentionally by the driver. Note that, if the absolute value of the roll angular acceleration ARr is greater than the roll angular acceleration threshold ARrth, the control device 4 determines that the lever 2B has moved both left and right due to a change in the behavior of the vehicle while traveling on a rough road surface. Also, if the absolute value of the roll angular acceleration ARr is equal to or less than the roll angular acceleration threshold ARrth, the control device 4 determines that the lever 2B has not moved left or right due to a change in the behavior of the vehicle while traveling on a rough road surface. The roll angular acceleration threshold ARrth is a value within a range that can determine the behavior of the vehicle while traveling on a rough road surface. In this embodiment, the processing of step 208 is an example of a vehicle state quantity calculation processing. Also, the roll angular acceleration ARr is an example of a vehicle state quantity that indicates the behavior of the vehicle.

[0083] Next, if the absolute value of the roll angular acceleration ARr is greater than the roll angular acceleration threshold ARrth (step 208: YES), the control device 4 executes the process of step 205. Note that in step 205, the control device 4 may calculate the correction operation amount θc based on the roll angular acceleration ARr. In this case, the correction gain K only needs to play a role in changing the dimension of the roll angular acceleration ARr to the dimension of the tilt angle θlr(X) of the lever 2B. On the other hand, if the absolute value of the roll angular acceleration ARr is equal to or less than the roll angular acceleration threshold ARrth (step 208: NO), the control device 4 executes the process of step 207.

[0084] According to the third embodiment described above, the same actions and effects as those of the second embodiment can be obtained, and also the same effects as those of (2-1) to (2-3) of the second embodiment can be obtained.

[0085] <Fourth embodiment> Next, a fourth embodiment of the steering control device will be described. This embodiment basically has the same configuration as the first embodiment. Therefore, detailed descriptions of the same members and configurations as the first embodiment will be omitted. This embodiment differs from the first embodiment in the configuration of the control device 4.

[0086] As indicated by the two-dot chain line in FIG. 1, the control device 4 according to this embodiment refers to the detection result of the gyro sensor 43 mounted on the vehicle, similarly to the second embodiment. <Configuration of control device 4> As shown in Fig. 10, the control device 4 according to this embodiment has a disturbance observer 80 and a subtractor 90 instead of the correction inclination angle calculation unit 62. The disturbance observer 80 is a process that calculates a correction operation amount θc using the vehicle speed V, the pinion angle θp, and the roll rate Rr as inputs. The disturbance observer 80 estimates the behavior of the vehicle, thereby estimating the operation amount that affects the left and right operation of the lever 2B as the disturbance operation amount, and sets this as the correction operation amount θc. In other words, the disturbance observer 80 is a process that detects the behavior of the vehicle while traveling on a rough road surface, and also a process that detects unintended left and right operation of the lever 2B by the driver.

[0087] In detail, the disturbance observer 80 has a roll angle estimation calculation unit 81 , a roll angle calculation unit 82 , a subtractor 83 , a tilt angle inverse calculation unit 84 , and a tuning calculation unit 85 . The roll angle estimation calculation unit 81 receives the vehicle speed V and the pinion angle θp as inputs and calculates the estimated roll angle Rat. The roll angle estimation calculation unit 81 calculates the estimated roll angle Rat, for example, based on a model that correlates the vehicle speed V, the pinion angle θp, and the estimated roll angle Rat. The model may be optimized according to vehicle characteristics that vary depending on the type of vehicle on which the steering device 1 is mounted, etc. Note that the estimated roll angle Rat can also be calculated by the CPU through map calculation using map data stored in advance in the memory of the control device 4.

[0088] The roll angle calculation unit 82 receives the roll rate Rr as an input and calculates the roll angle Ra. The roll angle calculation unit 82 calculates the roll angle Ra by integrating the roll rate Rr.

[0089] The subtractor 83 calculates the roll deviation ΔRa by subtracting the roll angle Ra from the estimated roll angle Rat. In this embodiment, the roll angle estimation calculation unit 81, the roll angle calculation unit 82, and the subtractor 83 are an example of a vehicle state quantity calculation process.

[0090] The tilt angle inverse calculation unit 84 is a process that receives the roll deviation ΔRa as an input and calculates the corrective manipulated variable θc. The tilt angle inverse calculation unit 84 can be realized, for example, by receiving the roll deviation ΔRa as an input and using an inverse conversion map, which is map data pre-stored in the memory of the control device 4, to calculate the corrective manipulated variable θc through map calculation by the CPU. This inverse conversion map may be data that inverts the relationship between the input variables and the output variables of the conversion map M2. In this embodiment, the tilt angle inverse calculation unit 84 is an example of a corrective manipulated variable calculation process.

[0091] The tuning calculation unit 85 is a process that receives the corrective manipulated variable θc as an input and calculates the final corrective manipulated variable θc. The tuning calculation unit 85 may include, for example, at least one of the processes (A) to (D) described below.

[0092] The process (A) is a process for calculating the final correction operation amount θc by multiplying the correction operation amount θc by a gain corresponding to the vehicle speed V. Process (B) is a process for calculating the final corrective operation amount θc based on the value of the roll deviation ΔRa when the absolute value of the estimated roll angle Rat, the roll angle Ra, or the roll deviation ΔRa is greater than a threshold value. Note that process (B) is a process for calculating a value of zero as the final corrective operation amount θc regardless of the value of the roll deviation ΔRa when the absolute value of the estimated roll angle Rat, the roll angle Ra, or the roll deviation ΔRa is equal to or less than a threshold value.

[0093] The process (C) is a process for calculating the final corrective manipulated variable θc by multiplying the corrective manipulated variable θc by a gain according to the pinion angle θp. Process (D) is a process for calculating the final corrective operation amount θc based on the value of the roll deviation ΔRa when the value of the inclination angle θlr(X) is greater than a threshold value. Note that process (D) is a process for calculating a value of zero as the final corrective operation amount θc regardless of the value of the roll deviation ΔRa when the absolute value of the inclination angle θlr(X) is equal to or less than a threshold value.

[0094] The final corrective manipulated variable θc obtained by the calculation of the disturbance observer 80 is output to a subtractor 90. The subtractor 90 calculates the corrected inclination angle θlr by subtracting the final corrective manipulated variable θc from the inclination angle θlr(X).

[0095] When the control device 4 detects an unintended left or right operation of the lever 2B by the driver, the control device 4 reflects the unintended left or right operation of the lever 2B by subtracting the correction operation amount θc through the subtractor 90, thereby eliminating the unintended left or right operation of the lever 2B by the driver. As a result, the control device 4 reflects the correction operation amount θc in the current command value calculated by the correction inclination angle θlr that reflects the correction operation amount θc, i.e., the operation signal. In this embodiment, the subtractor 90 is an example of a correction reflection process. Also, in this embodiment, the disturbance observer 80 and the subtractor 90 are an example of an operation amount calculation unit.

[0096] According to the fourth embodiment described above, the same actions and effects as those of the first embodiment can be obtained, and further the following actions and effects can be obtained. (4-1) When the disturbance observer 80 is employed, the behavior of the vehicle can be estimated to improve the accuracy of detecting the behavior of the vehicle while traveling on a rough road, i.e., detecting unintentional left / right operation of the lever 2B by the driver. This is effective in optimizing the operability according to the traveling state of the vehicle.

[0097] (4-2) When the disturbance observer 80 is employed, it is possible to improve the accuracy of calculating the amount of left and right operation of the lever 2B unintentionally performed by the driver. This is effective in optimizing the operability depending on the running state of the vehicle.

[0098] <Other embodiments> The above-described embodiments can be modified as follows: The above-described embodiments and the following modifications can be combined with each other within the scope of technical compatibility.

[0099] In the first embodiment, the control device 4 may be configured to include processing corresponding to steps 204 to 207, which is processing using the roll rate Rr, as in the second embodiment. In this case, the control device 4 may be configured to execute processing corresponding to steps 204 to 207 after processing of step 103: NO. The control device 4 may also be configured to execute processing of steps 103 to 106 after processing corresponding to step 204: NO. The control device 4 may also include processing to calculate the corrective operation amount θc by taking into account the longitudinal change amount Δθlr(Y) and the roll rate Rr. Note that, as in the second embodiment, the control device 4 may be configured to refer to the detection results of the gyro sensor 43 installed in the vehicle.

[0100] In the first embodiment, the correction gain map M1 in Fig. 4 may be data in which the vehicle speed V and the pinion angle θp are input variables and the correction gain K is an output variable. In this case, the processing in step 104 may include processing for changing the relationship of the correction gain K to the vehicle speed V, regardless of the pinion angle θp. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0101] In the first embodiment, the correction gain map M1 in Fig. 4 may be data in which the target pinion angle θp* is used as an input variable instead of the pinion angle θp, and the correction gain K is used as an output variable. In this case, the processing in step 104 may include processing for changing the relationship of the correction gain K with respect to the target pinion angle θp*. The other embodiments described herein can be similarly applied to the processing in step 205 in the second and third embodiments.

[0102] In the first embodiment, the characteristic of the correction gain map M1 in Fig. 4 may be such that the value of the correction gain K changes nonlinearly with changes in the absolute value of the pinion angle θp. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0103] In the first embodiment, the conversion map M2 and the vehicle speed gain map M3 may be data that uses the correction inclination angle θlr and the vehicle speed V as input variables and the target pinion angle θp* as an output variable. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0104] In the first embodiment, the correction gain map M1 may be any type of variable defined as an input variable and an output variable, as long as it has the characteristics described in the first embodiment. For example, the input variable and the output variable may be positive and negative variables, or may be absolute value variables. Note that, when absolute value variables are used, the process of step 104 may include a process of calculating the positive or negative value of the absolute value output variable depending on the positive or negative value of the input variable before processing into the absolute value. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0105] In the first embodiment, the correction gain map M1 may include multiple maps. For example, the multiple maps may include a map to be referenced when the pinion angle θp has a positive value and a table to be referenced when the pinion angle θp has a negative value. For example, the number of multiple maps may be determined according to the combination of positive and negative values ​​of the pinion angle θp.

[0106] In the first embodiment, the processing in step 106 may be processing to calculate a fixed value other than zero as the correction operation amount θc, as long as the value is within a range that does not affect the target pinion angle θp* when reflected in the left and right operation amounts of the lever 2B. Also, the processing in step 106 is not limited to a fixed value, and may be processing to calculate a variable value as the correction operation amount θc. The other embodiments described here can be similarly applied to the processing in step 207 in the second and third embodiments.

[0107] In the first embodiment, the control device 4 may be configured to calculate the inclination angle θlr(X) input in step 101 as the corrected inclination angle θlr without executing the process of step 105 after the process of step 106. The other embodiments described herein can be similarly applied to the process of step 207 in the second and third embodiments.

[0108] In the first embodiment, the processing procedure of the control device 4 is not limited to the procedure shown in Fig. 3 and can be changed as appropriate. For example, the order of steps 101 and 102 shown in Fig. 3 may be changed. The other embodiments described herein can be similarly applied to the processing of the second and third embodiments. That is, the order of steps 201, 202, and 203 shown in Fig. 8 may be changed.

[0109] In the first embodiment, control device 4 may be configured to include a process for reflecting the corrective manipulated variable θc on any of target pinion angle base value θpb*, target pinion angle θp*, and pinion angle θp. Alternatively, control device 4 may be configured to include a process for reflecting the corrective manipulated variable θc on any of steering torque command value Tp* or a current command value. Control device 4 may also be configured to include a process for reflecting the corrective manipulated variable θc on a current command value. In these cases, pinion angle calculation unit 61, target pinion angle calculation unit 63, pinion angle feedback control unit 64, or energization control unit 65 are examples of the corrective manipulated variable calculation process and the correction process. It is sufficient for control device 4 to include a process for calculating the corrective manipulated variable θc so as to correspond to a target on which the corrective manipulated variable θc is reflected. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0110] In the first embodiment, the control device 4 may be configured not to reflect the correction operation amount θc in the inclination angle θlr(X) when the lever 2B is in the neutral position. In this case, the control device 4 may, for example, include a process of calculating a value of zero as the correction operation amount θc, or may not execute the processes of steps 101 to 106. The other embodiments described here can be similarly applied to the second to fourth embodiments.

[0111] In the first embodiment, in the process of step 103, the change threshold value Δθth may be changed depending on the vehicle running conditions such as the vehicle speed V and the pinion angle θp. The other embodiments described herein can be similarly applied to the process of step 204 in the second and third embodiments.

[0112] In the first embodiment, the average value, variance, or first-order time differential value of the tilt angle θlr(Y) may be calculated as the longitudinal change amount Δθlr(Y) in step 103. The other embodiments described herein can be similarly applied to the process of step 204 in the second and third embodiments.

[0113] In the first embodiment, the process of step 103 may be a process of only calculating the longitudinal change amount Δθlr(Y). In other words, the process of comparing the longitudinal change amount Δθlr(Y) with the change threshold value Δθth may be omitted from the process of step 103. In this case, the control device 4 can omit the process of step 106. The other embodiments described herein can also be similarly applied to the process of step 204 in the second and third embodiments. In this case, the control device 4 can omit the process of step 207.

[0114] In the first embodiment, the control device 4 may be configured to include a process for learning the driver's characteristics and habits that change the inclination angle θlr(Y) when operating the lever 2B left or right. In this case, the control device 4 may include a process for calculating the correction operation amount θc so that the results of the learning are reflected. For example, various algorithms such as machine learning can be used for such learning. This makes it possible to more accurately detect situations in which the lever 2B moves due to changes in the vehicle's behavior depending on the road conditions.

[0115] In the second embodiment, the control device 4 may refer to a physical quantity capable of estimating the vehicle behavior, instead of the roll rate Rr. Such physical quantities are vehicle information including, for example, the pitch rate, yaw rate, and lateral acceleration of the vehicle. Other examples of the physical quantities include estimated quantities obtained by estimating from vehicle information including the stroke amount of the suspension related to the steered wheels 5, the ground load, and changes in vehicle height. In these cases, in step 203, the control device 4 may input one of the physical quantities and include processing corresponding to steps 204 to 207 using the input physical quantity. The control device 4 may also include processing for inputting multiple of the physical quantities, or may include processing corresponding to steps 204 to 207 using the multiple physical quantities. The control device 4 may refer to the detection results of the gyro sensor 43, or may refer to the detection results of an on-board acceleration sensor, for example.

[0116] In the second embodiment, when a single-axis lever is used, a dial may be used as the operating member of the operation unit 2 instead of the lever 2B. The dial can be rotated clockwise or counterclockwise from a neutral position. To turn the vehicle to the right relative to the traveling direction, the dial is rotated clockwise. To turn the vehicle to the left relative to the traveling direction, the dial is rotated counterclockwise. In this case, a rotation angle sensor is provided in the operation unit 2. The rotation angle sensor detects the rotation angle of the dial. The control device 4 may perform various processes using the detection result of the rotation angle sensor instead of the inclination angle θlr(X). Alternatively, the operating member may be of a touch sensor type, as long as its position can be changed in multiple steps in two different directions relative to a position corresponding to the neutral position. The other embodiments described herein can be similarly applied to the processes of the third and fourth embodiments.

[0117] In the second embodiment, when a single-axis lever is used, the lever 2B may be supported slidably relative to the base 2A. In this case, the control device 4 may execute various processes using the amount of sliding of the lever 2B instead of the inclination angle θlr(X). The other embodiments described herein can be similarly applied to the processes of the third and fourth embodiments.

[0118] In the third embodiment, the process of step 208 may be implemented as a process using jerk instead of roll rate Rr. Also, in step 205, the control device 4 may calculate the corrective manipulated variable θc based on the jerk. Note that there is a correlation between the roll rate Rr and the jerk. By utilizing this correlation, it is possible to calculate the corrective manipulated variable θc that provides the same actions and effects as those of the third embodiment.

[0119] In the fourth embodiment, the disturbance observer 80 may be configured to include a process for calculating the estimated lateral acceleration and the lateral acceleration using the vehicle speed V, pinion angle θp, and roll rate Rr, instead of the roll angle estimation calculation unit 81 and the roll angle calculation unit 82. In this case, the disturbance observer 80 may include a process for calculating the corrective manipulated variable θc using the estimated lateral acceleration and a lateral acceleration deviation, which is the deviation between the lateral acceleration, instead of the tilt angle inverse calculation unit 84. Alternatively, the disturbance observer 80 may calculate the lateral acceleration by referring to the lateral acceleration occurring in the vehicle, instead of the roll rate Rr. Note that there is a correlation between the roll angle Ra and the lateral acceleration. Utilizing this correlation, it is possible to calculate the corrective manipulated variable θc that achieves the same functions and effects as those of the fourth embodiment.

[0120] In the fourth embodiment, the disturbance observer 80 may be configured to include a process of referring to the inclination angle θlr(Y) and reflecting the inclination angle θlr(Y) in the correction operation amount θc, as in the first embodiment.

[0121] In the fourth embodiment, the lever 2B may be a single-axis lever capable of detecting tilting, which is an operation in one direction. The one direction is the X-axis direction. The other embodiments described herein can achieve the same functions and effects as the fourth embodiment.

[0122] In the fourth embodiment, the tuning calculation unit 85 may be omitted from the disturbance observer 80. In the fourth embodiment, the subtractor 90 may be implemented as a process of the disturbance observer 80. In this case, the disturbance observer 80 is an example of a corrective manipulated variable calculation process and a correction process.

[0123] In each of the above embodiments, the control device 4 may be configured to refer to the inclination angles θlr(X),(Y) after filtering via a noise reduction filter. The other embodiments described herein can be similarly applied to the roll rate Rr in the second and third embodiments.

[0124] In each of the above embodiments, the control device 4 can also use the tilt angle θlr(X) as a value indicating the proportion of the tilt range in the X-axis direction from the neutral position. The same applies to the tilt angle θlr(Y).

[0125] In each of the above embodiments, the control device 4 may be configured to refer to the coordinates in the X-axis direction and the Y-axis direction as the operation amount of the lever 2B. In each of the above embodiments, the control device 4 steers the steered wheels 5 in accordance with the inclination angle θlr(X). However, the control device 4 may also steer the steered wheels 5 in accordance with the operating force applied to the lever 2B. The operating force is the force required to operate the lever 2B. In this case, a pressure sensor is provided in the operation unit 2. The pressure sensor detects the operating force applied to the lever 2B. The control device 4 may execute processing to calculate the target pinion angle θp* using the detection result of the pressure sensor instead of the inclination angles θlr(X), (Y). The other embodiments described here can be similarly applied to the processing of the second and third embodiments.

[0126] In each of the above embodiments, a mobile terminal incorporating a gyro sensor having multiple detection axes may be used as the operating member instead of the lever 2B. Examples of mobile terminals include smartphones and tablet terminals. In this case, the gyro sensor of the mobile terminal detects the rotation amount of the mobile terminal as the operation amount. The control device 4 may perform various processes using the detection results of the gyro sensor of the mobile terminal instead of the inclination angles θlr(X),(Y).

[0127] In each of the above embodiments, the steering device 1 may have a steering wheel. When the operation unit 2 and the steering wheel coexist, the operation terminal to be used is switched between the operation unit 2 and the steering wheel, for example, by operating a switch provided in the driver's seat. In this case, the steering device 1 may have a reaction force mechanism that applies a steering reaction force to the steering wheel.

[0128] In each of the above embodiments, the steering device 1 can take over driving while the vehicle is traveling, and can also realize autonomous driving by providing various driving assistance functions to further improve the comfort of the vehicle. Examples of driving assistance functions include functions to prevent the vehicle from leaving its lane and to assist in emergency avoidance.

[0129] In each of the above embodiments, the operation unit 2 may include a motor that generates an operation reaction force that resists the operation of the lever 2B. In this case, the inclination angle θlr(X) may be detected based on the rotation angle of the motor.

[0130] In each of the above embodiments, the pinion angle θp may be calculated from, for example, the stroke amount of the steered shaft 22 or the steered angle θw itself, instead of the rotation angle θb. In each of the above embodiments, operation of the lever 2B in the Y-axis direction may be used to control the driving / braking of the vehicle.

[0131] In each of the above embodiments, the steering device 1 has a linkless structure in which the power transmission path between the operation unit 2 and the steering unit 3 is separated, but this is not limited to this. For example, if the steering device 1 is equipped with a steering wheel, it may have a structure in which the power transmission path between the operation unit 2 and the steering unit 3 can be separated by a clutch.

[0132] In each of the above embodiments, steering unit 3 transmits the rotation of steering motor 31 to conversion mechanism 33 via transmission mechanism 32, but this is not limiting. For example, steering unit 3 may be configured so that the rotation of steering motor 31 is transmitted to conversion mechanism 33 via a gear mechanism. Also, steering unit 3 may be configured so that steering motor 31 directly rotates conversion mechanism 33. Furthermore, steering unit 3 may be configured to include a second rack-and-pinion mechanism, and so that the rotation of steering motor 31 is converted into reciprocating motion of steering shaft 22 by the second rack-and-pinion mechanism. [Explanation of symbols]

[0133] 1...Steering device 2...Operation unit 2B...Lever (operating member) 3...Steering unit 4...Control device (steering control device, turning control unit) 5...Steering wheel 43...Gyro sensor (sensor) 62...Correction inclination calculation section (operated amount calculation section) 63...Target pinion angle calculation unit (target steering operation amount calculation unit) 65...Electrification control unit (operation signal calculation unit)

Claims

1. A steering control device that controls a steering device of a vehicle, the steering device has a structure in which a power transmission path between an operation unit having an operation member and a steering unit configured to steer the steered wheels is separated, and a resolution of the operation amount of the operation member is lower than a resolution of the steering amount of the steered wheels, the steering control device includes a steering control unit that calculates an operation signal to operate the steering unit based on the operation of the operation member, The steering control unit is a vehicle state quantity calculation process for calculating a vehicle state quantity indicating a behavior of the vehicle; a correction operation amount calculation process for calculating a correction operation amount for correcting the operation of the operation member based on the vehicle state amount; and a correction process for reflecting the correction operation amount when calculating the operation signal.

2. 2. The steering control device according to claim 1, wherein the correction operation amount calculation process calculates the correction operation amount corresponding to a change amount of the operation member relative to the vehicle state amount.

3. the operating member is a two-axis lever capable of detecting operations in two different directions, 3. The steering control device according to claim 2, wherein the vehicle state quantity calculation process includes a process of calculating the vehicle state quantity based on an operation amount in a specific direction of the operation amounts of the levers of the two axes.

4. the vehicle state quantity calculation process includes a process of calculating the vehicle state quantity based on vehicle information other than the operation amount of the operation member, The steering control device according to claim 2 , wherein the vehicle information is a sensor value detected by a sensor mounted on the vehicle.

5. The steering control unit is an operation amount calculation unit that calculates an operation amount of the operation member based on an operation of the operation member; a target steering operation amount calculation unit that calculates a target steering operation amount, which is a target value of the steering operation amount, based on the operation amount of the operating member; an operation signal calculation unit that calculates the operation signal based on the target steering operation amount, the steering operation amount is information obtained from the steering unit, the operation amount calculation unit includes the vehicle state amount calculation processing, the corrected operation amount calculation processing, and the correction processing, 5. The steering control device according to claim 2, wherein the correction process is a process of reflecting the correction operation amount on the operation amount of the operation member.

6. A steering control method for controlling a steering device of a vehicle, comprising: the steering device has a structure in which a power transmission path between an operation unit having an operation member and a steering unit configured to steer the steered wheels is separated, and a resolution of the operation amount of the operation member is lower than a resolution of the steering amount of the steered wheels, the steering control method includes calculating an operation signal for actuating the steering unit based on an operation of the operation member, The calculating of the operation signal includes: a vehicle state quantity calculation process for calculating a vehicle state quantity indicating a behavior of the vehicle; a correction operation amount calculation process for calculating a correction operation amount for correcting the operation of the operation member based on the vehicle state amount; a correction process for reflecting the correction operation amount when calculating the operation signal.

Images