Steering control device and steering control method

Abstract

The present application relates to a steering control device and a steering control method. A steering control device (1) includes a target steering response value calculation unit configured to calculate a target value, i.e., a target steering response value, which is a value that can be converted into a value of a steering angle (θi) of a steering wheel (3); and a control signal generation unit configured to generate a control signal for operating a steering unit (5) based on the target steering response value. The target steering response value calculation unit is configured to perform a low sensitivity determination process for determining whether a low sensitivity condition, in which a change amount of the steering angle with respect to a change amount of an operation amount (θl) of an operation lever (11) is reduced, is established; a normal calculation process for calculating the target steering response value based on the operation amount when the low sensitivity condition is not established; and a low sensitivity calculation process for calculating the target steering response value having an absolute value smaller than the target steering response value calculated by the normal calculation process based on the operation amount when the low sensitivity condition is established.

Description

Technical Field

[0001] This invention relates to a steering control device and a steering control method. Background Technology

[0002] Conventionally, there are electric steering systems where the power transmission path between the operating unit connected to the steering wheel and the steering unit that steers the steering wheels is separated. For example, as described in Patent Document 1, a steering control device that controls such a steering system changes the angle ratio of the steering wheel's steering angle to the steering wheel's steering angle according to the vehicle's driving conditions.

[0003] Patent document 2 discloses a control component used by the driver, which employs a lever instead of a steering wheel. When the lever is the control component, compared to when the steering wheel is the control component, the amount of operation required to turn the steering wheel can be reduced, thus improving driver convenience.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2021-30837

[0005] Patent Document 2: Japanese Patent Application Publication No. 8-34353

[0006] As described above, when the control lever is the operating component, reducing the amount of operation required to turn the steering wheel results in a larger change in the steering angle relative to the change in the amount of operation. That is, even reducing the amount of operation on the control lever results in a significant change in the steering angle of the steering wheel. Therefore, it is difficult to perform fine adjustments to the steering angle of the steering wheel. Summary of the Invention

[0007] In one embodiment of the present invention, a steering control device for controlling a vehicle steering mechanism is provided. The steering mechanism has a structure that separates the power transmission path between an operating unit having a lever and a steering unit configured to steer the steering wheels. The steering control device includes: a target steering correspondence value calculation unit configured to calculate a target value, i.e., a target steering correspondence value, that can be converted into a convertible value of the steering angle of the steering wheels; and a control signal generation unit configured to generate a control signal for actuating the steering unit based on the target steering correspondence value. The target steering correspondence value calculation unit is configured to perform the following processes: a low-sensitivity determination process that determines whether a low-sensitivity condition that reduces the change in steering angle relative to a change in the amount of operation of the lever is met; a normal calculation process that, if the low-sensitivity condition is not met, calculates the target steering correspondence value based on the amount of operation; and a low-sensitivity calculation process that, if the low-sensitivity condition is met, calculates a target steering correspondence value having an absolute value smaller than the target steering correspondence value calculated by the normal calculation process, based on the amount of operation.

[0008] In other embodiments of the present invention, a steering control method for controlling a vehicle steering control device is provided. The steering control device has a configuration that separates the power transmission path between an operating unit having an operating lever and a steering unit configured to steer the steering wheels. The steering control method includes: a step of calculating a target value, i.e., a target steering correspondence value, that can be converted into a convertible value of the steering angle of the steering wheels; and a step of generating a control signal that actuates the steering unit based on the target steering correspondence value. The step of calculating the target steering correspondence value includes performing the following processes: a low-sensitivity determination process that determines whether a low-sensitivity condition that reduces the change in the steering angle relative to a change in the amount of operation of the operating lever is met; a normal calculation process that calculates the target steering correspondence value based on the operating amount when the low-sensitivity condition is not met; and a low-sensitivity calculation process that calculates a target steering correspondence value based on the operating amount whose absolute value is smaller than the target steering correspondence value calculated by the normal calculation process when the low-sensitivity condition is met. Attached Figure Description

[0009] Figure 1 This is a simplified structural diagram of a steering control device according to one embodiment and a steering control device for controlling the steering control device.

[0010] Figure 2 It means Figure 1 A block diagram of the steering control device.

[0011] Figure 3A It means Figure 1 A diagram showing an example of a typical mapping table for a steering control device. Figure 3B It means Figure 1 A diagram illustrating an example of a low-sensitivity mapping table in a steering control device.

[0012] Figure 4 It means by Figure 1 A flowchart illustrating an example of the processing sequence of the target steering angle calculation performed by the target steering angle calculation unit of the steering control device.

[0013] Figure 5 It means by Figure 1 A flowchart illustrating an example of the processing sequence of the protection processing unit performed by the steering control device.

[0014] Figure 6 It means by Figure 1 A flowchart illustrating an example of the processing sequence for calculating the upper limit speed performed by the protection processing unit of the steering control device. Detailed Implementation

[0015] The following describes one embodiment of the steering control device with reference to the accompanying drawings.

[0016] (Overall structure)

[0017] like Figure 1 As shown, the steering control device 1 controls the electric steering device 2. The steering device 2 changes the vehicle's direction of travel by turning the steering wheels 3 according to the driver's operation. The steering device 2 includes an operating unit 4 operated by the driver and a steering unit 5 that turns the steering wheels 3. The steering device 2 has a structure that mechanically separates the power transmission path between the operating unit 4 and the steering unit 5.

[0018] The operating unit 4 includes a control lever 11 operated by the driver and a base 12 supporting the control lever 11 so that it can tilt. In this embodiment, the base 12 supports the control lever 11 so that it can tilt laterally, i.e., in the left-right direction of the vehicle, and the control lever 11 tilts laterally by the driver's operation. That is, the amount of operation by the driver is represented by the tilt angle of the control lever 11 (hereinafter referred to as the lever tilt angle θl). In other embodiments, the base 12 may also support the control lever 11 so that it can tilt in the longitudinal direction of the vehicle.

[0019] In the illustrated example, the operating unit 4 includes a tilt angle sensor 13 that detects the tilt angle θl of the lever. Although the lever tilt angle θl detects a positive value for tilting the operating lever 11 to the right and a negative value for tilting the operating lever 11 to the left, it can also be the other way around.

[0020] Furthermore, the operation unit 4 includes a sensitivity switch 14 operated by the driver. As described later, the sensitivity switch 14 is used to change the angle ratio α of the steering angle θi of the steering wheel 3 relative to the lever inclination angle θl of the operating lever 11, according to the driver's intention. The angle ratio α is a value obtained by dividing the steering angle θi by the lever inclination angle θl (α = θi / θl). A switch signal Ss indicating the on or off state of the sensitivity switch 14 is output from the sensitivity switch 14 to the steering control device 1. In this embodiment, the sensitivity switch 14 is a type of switch that continuously switches between on and off states by the driver pressing it once. The sensitivity switch 14 is provided, for example, on the operating lever 11, but is not limited thereto, and can also be provided at any position that the driver can operate, such as the base 12 or near the driver's seat.

[0021] The steering unit 5 includes: a pinion shaft 21, a rack shaft 22 connected to the pinion shaft 21, a rack housing 23 that houses the rack shaft 22 in a reciprocating manner, and a rack and pinion mechanism 24 having the pinion shaft 21 and the rack shaft 22. The rack and pinion mechanism 24 is configured by meshing the pinion teeth 21a formed on the pinion shaft 21 and the rack teeth 22a formed on the rack shaft 22. Thus, the pinion shaft 21 rotates according to the reciprocating movement of the rack shaft 22. Connecting rods 26 are attached to both ends of the rack shaft 22 via ball joints 25. The front end of the connecting rod 26 is connected to a steering knuckle (not shown) on which the steering wheel 3 is assembled.

[0022] Additionally, the steering unit 5 includes a steering actuator 31 that applies a force, i.e., a steering force, to the rack shaft 22 to turn the steering wheel 3. In the illustrated example, the steering actuator 31 includes a steering motor 32 and a power transmission mechanism 33 that transmits the torque of the steering motor 32 to the rack shaft 22. The power transmission mechanism 33 includes a belt mechanism 34 and a ball screw mechanism 35. The steering actuator 31 transmits the rotation of the steering motor 32 to the ball screw mechanism 35 via the belt mechanism 34, which is then converted into reciprocating movement of the rack shaft 22 by the ball screw mechanism 35, thereby applying a steering force to the steering wheel 3.

[0023] In this steering control device 2, a steering force is applied from the steering actuator 31 according to the driver's operation of the control lever 11. This causes the rack shaft 22 to reciprocate, changing the steering angle θi of the steering wheel 3. In other words, the steering actuator 31 turns the steering wheel 3 according to the driver's operation.

[0024] The steering control device 1 is connected to the steering motor 32 and controls the operation of the steering motor 32. Additionally, the steering control device 1 is connected to the transmitter 37 and controls the operation of the transmitter 37. The transmitter 37 can be any device that outputs physical quantities that the driver can perceive through his five senses, such as a display panel or a speaker.

[0025] The detection results from various sensors are input to the steering control unit 1. These sensors include, for example, the tilt angle sensor 13, vehicle speed sensor 41, rotation angle sensor 42, and acceleration sensor 43. The vehicle speed sensor 41 detects the vehicle speed V, which is the vehicle's travel speed. The rotation angle sensor 42 detects the rotation angle θt of the steering motor 32's rotation axis within a 360° range. In this embodiment, the acceleration sensor 43 detects the vehicle's lateral acceleration GY and vertical acceleration GZ. While vertical acceleration GZ is detected as positive for upward acceleration and negative for downward acceleration, the opposite can also be true. In other embodiments, the acceleration sensor can detect not only lateral acceleration GY and vertical acceleration GZ, but also the vehicle's front-to-back acceleration. Furthermore, in other embodiments, the lateral acceleration sensor detecting lateral acceleration GY and the vertical acceleration sensor detecting vertical acceleration GZ can be connected to the steering control unit 1 independently.

[0026] The switching signal Ss of the aforementioned sensitivity switch 14 is input to the steering control device 1. Furthermore, a position signal Sp is input to the steering control device 1 from a position sensor 44 (not shown) that detects the gear position of the gear lever. Gear positions include, for example, the parking position P when the vehicle is stopped, the reverse position R when the vehicle is reversed, and the driving position D when the vehicle is forward. Moreover, the steering control device 1 controls the operation of the steering motor 32 based on the input state variables.

[0027] (Steering control device 1)

[0028] The structure of the steering control device 1 will be described in detail below.

[0029] like Figure 2 As shown, the steering control device 1 includes a microcomputer 51 that outputs a control signal Mt, and a drive circuit 52 that supplies power to the steering motor 32 based on the control signal Mt.

[0030] The microcomputer 51, as a processing circuit, can be constructed from (1) one or more processors that operate according to a computer program (software), (2) one or more dedicated hardware circuits such as an application-specific integrated circuit (ASIC) that executes at least a portion of various processes, or (3) a combination thereof. The processor includes a CPU and memories such as RAM and ROM, which store program codes or instructions configured to cause the CPU to execute processes. Memory, or non-transitory computer-readable medium, includes all available media accessible by a general-purpose or special-purpose computer. Various controls performed by the microcomputer 51 are executed by the CPU executing programs stored in memory at predetermined operating cycles.

[0031] The drive circuit 52 employs, for example, a typical PWM inverter with multiple switching elements such as FETs or IGBTs. The control signal Mt is a gate on / off signal that specifies the on or off state of each switching element.

[0032] The microcomputer 51 outputs a control signal Mt to the drive circuit 52, thereby supplying power corresponding to the control signal Mt from the vehicle power supply to the steering motor 32. As a result, the steering motor 32 rotates, applying steering force to the steering wheel 3 as described above. Thus, the steering control device 1 controls the motor torque generated by the steering motor 32 by supplying power to it, thereby turning the steering wheel 3.

[0033] (Microcomputer 51)

[0034] The following details the structure of the microcomputer 51.

[0035] The microcomputer 51 performs calculations through the following control blocks at a predetermined calculation cycle, and outputs a control signal Mt. The microcomputer 51 is input with the vehicle speed V, lever tilt angle θl, rotation angle θt, lateral acceleration GY, vertical acceleration GZ, switch signal Ss, and position signal Sp. Based on these state variables, the microcomputer 51 generates and outputs the control signal Mt.

[0036] In detail, the microcomputer 51 includes a steering angle calculation unit 61 for calculating the steering angle θp, a target steering angle calculation unit 62 for calculating the target value of the steering angle θp, i.e., the target steering angle θp*, and a control signal generation unit 63 for generating the control signal Mt.

[0037] The rotation angle θt of the steering motor 32 is input to the steering angle calculation unit 61. The steering angle calculation unit 61 calculates, for example, the rotational speed of the steering motor 32 starting from the midpoint, and accumulates the rotation angle θt with the midpoint as zero degrees, thereby calculating the accumulated angle. Furthermore, the steering angle calculation unit 61 multiplies this accumulated angle by a conversion factor based on the reduction ratio of the belt mechanism 34, the lead of the ball screw mechanism 35, and the rotational speed ratio of the rack and pinion mechanism 24, thereby calculating the steering angle θp. That is, the steering angle θp corresponds to the rotation angle of the pinion shaft 21, i.e., the pinion angle, where the midpoint is the rotation angle of the pinion shaft 21 when the vehicle is moving forward. As described above, the pinion shaft 21 rotates according to the reciprocating movement of the rack shaft 22, so the rotation angle of the pinion shaft 21, i.e., the steering angle θp, corresponds to the actual value that can be converted into the steering angle θi of the steering wheel 3, i.e., the steering angle value. The steering angle calculation unit 61 is equivalent to the steering angle value calculation unit. The steering angle θp calculated by the steering angle calculation unit 61 is output to the control signal generation unit 63.

[0038] The vehicle speed V, lever tilt angle θl, lateral acceleration GY, vertical acceleration GZ, switch signal Ss, and position signal Sp are input to the target steering angle calculation unit 62. Based on the above state variables, the target steering angle calculation unit 62 calculates the target value of the steering angle θp, which is also the target steering angle θp*. That is, the target steering angle θp* is equivalent to the target value that can be converted into the steering angle θi of the steering wheel 3, which is also the target steering angle value. The target steering angle calculation unit 62 is equivalent to the target steering angle value calculation unit. The calculation process of the target steering angle θp* performed by the target steering angle calculation unit 62 will be described later. The target steering angle θp* is output to the control signal generation unit 63.

[0039] The vehicle speed V, lever tilt angle θl, steering angle θp, target steering angle θp*, and mode signal Sm (described later) are input to the control signal generation unit 63. Based on the above state variables, the control signal generation unit 63 generates a control signal Mt.

[0040] In detail, the control signal generation unit 63 includes a subtractor 71, a protection processing unit 72, and a feedback control unit 73. Furthermore, hereinafter, the term "feedback" will sometimes be referred to as "F / B".

[0041] The subtractor 71 is input with the steering angle θp and the target steering angle θp*. The subtractor 71 calculates the difference Δθp by subtracting the steering angle θp from the target steering angle θp*. The difference Δθp is output to the protection processing unit 72.

[0042] In addition to the differential Δθp, the protection processing unit 72 also receives the vehicle speed V, the pole tilt angle θl, and the mode signal Sm. Based on these state variables, the protection processing unit 72 calculates a differential Δθpg that limits the differential Δθp to below the upper limit value Δθlim. The upper limit value Δθlim is a value set based on the upper limit speed of the steering wheel 3. The protection processing of the differential Δθp performed by the protection processing unit 72 will be described later. The differential Δθpg after protection processing is output to the F / B control unit 73.

[0043] The differential value Δθpg after protection processing is input to the F / B control unit 73. The F / B control unit 73 calculates the target steering torque by performing F / B calculation based on the differential value Δθpg. As an example, the F / B calculation uses PID control, but it is not limited to this and can also be PI control, etc. Moreover, the F / B control unit 73 uses any known technique to generate a control signal Mt such that the steering motor 32 generates the target steering torque.

[0044] As described above, the difference Δθpg used for F / B calculation is limited to a difference upper limit value Δθlim corresponding to the upper limit speed. Therefore, if power is supplied from the drive circuit 52 to the steering motor 32 according to the control signal Mt, the steering wheel 3 is turned in such a way that the steering speed below the upper limit speed becomes the steering angle θi corresponding to the target steering angle θp*. That is, the control signal generation unit 63 generates the control signal Mt so as to set the steering speed of the steering wheel 3 to be below the upper limit speed.

[0045] (Target turning corresponding angle calculation unit 62)

[0046] Next, the calculation and processing of the target turning corresponding angle θp* performed by the target turning corresponding angle calculation unit 62 will be explained in detail.

[0047] The target steering angle calculation unit 62 performs low-sensitivity determination processing to determine whether a low-sensitivity condition is met, and prohibition determination processing to determine whether a prohibition condition is met. As described later, the low-sensitivity condition is used to determine whether the vehicle should reduce the change in steering angle θi relative to the change in pole tilt angle θl, i.e., whether the angle ratio α should be reduced. The prohibition condition is used to determine whether the vehicle should prohibit reducing the change in steering angle θi relative to pole tilt angle θl, i.e., whether reducing the angle ratio α should be prohibited.

[0048] When the low-sensitivity condition is not met or the prohibition condition is met, the target steering angle calculation unit 62 performs normal calculation processing to calculate the target steering angle θp* based on the pole tilt angle θl and the vehicle speed V. On the other hand, when the low-sensitivity condition is met and the prohibition condition is not met, the target steering angle calculation unit 62 performs low-sensitivity calculation processing to calculate the target steering angle θp*, which is smaller than the absolute value of the target steering angle θp* calculated by the normal calculation processing, based on the pole tilt angle θl and the vehicle speed V. That is, when the prohibition condition is met, the target steering angle calculation unit 62 does not perform low-sensitivity calculation processing, even when the low-sensitivity condition is met, but performs normal calculation processing to calculate the target steering angle θp*. Furthermore, the following will sometimes refer to the state where the target steering angle calculation unit 62 calculates the target steering angle θp* through normal calculation processing as a normal mode reference, and the state where the target steering angle θp* is calculated through low-sensitivity calculation processing as a low-sensitivity mode reference.

[0049] In detail, the target turning angle calculation unit 62 includes a memory 62a. The memory 62a stores a normal mapping table 81 for normal calculation information and a low-sensitivity mapping table 82 for low-sensitivity calculation information.

[0050] like Figure 3A as well as Figure 3B As shown, the normal mapping table 81 and the low-sensitivity mapping table 82 represent the relationship between the pole tilt angle θl, the vehicle speed V, and the target steering angle θp*. That is, the normal mapping table 81 and the low-sensitivity mapping table 82 are three-dimensional mapping tables representing the relationship between the target steering angle θp* and the pole tilt angle θl and the vehicle speed V. In the illustrated example, the target steering angle θp* is zero degrees when either the normal mapping table 81 or the low-sensitivity mapping table 82 is zero. Furthermore, both the normal mapping table 81 and the low-sensitivity mapping table 82 are set such that the larger the absolute value of the pole tilt angle θl, the larger the absolute value of the target steering angle θp*. Additionally, both the normal mapping table 81 and the low-sensitivity mapping table 82 are set such that the smaller the vehicle speed V, the larger the absolute value of the target steering angle θp*. Furthermore, the change in the absolute value of the target steering angle θp* relative to the change in pole tilt angle θl and vehicle speed V in the low-sensitivity mapping table 82 is set to be smaller than the change in the absolute value of the target steering angle θp* relative to the change in pole tilt angle θl and vehicle speed V in the normal mapping table 81. Therefore, except when the absolute value of the target steering angle θp* in the normal mapping table 81 is zero, the absolute value of the target steering angle θp* in the low-sensitivity mapping table 82 is smaller than the absolute value of the target steering angle θp* in the normal mapping table 81 for any pole tilt angle θl and vehicle speed V.

[0051] In normal operation, the target steering angle calculation unit 62 calculates the target steering angle θp* corresponding to the pole tilt angle θl and vehicle speed V by referring to the normal mapping table 81. Conversely, in low-sensitivity operation, the target steering angle calculation unit 62 calculates the target steering angle θp* corresponding to the pole tilt angle θl and vehicle speed V by referring to the low-sensitivity mapping table 82. In other words, the target steering angle calculation unit 62 switches between the mapping tables used in normal operation and low-sensitivity operation. Therefore, in low-sensitivity operation, the target steering angle calculation unit 62 calculates a target steering angle θp* with an absolute value smaller than the target steering angle θp* calculated by the normal operation.

[0052] When the prohibition condition is not met but the low sensitivity condition is met, the target steering angle calculation unit 62 outputs a mode signal Sm, indicating a low sensitivity mode, to the protection processing unit 72 and the aforementioned reporter 37. That is, the target steering angle calculation unit 62 performs report processing. This mode signal Sm is configured so that the target steering angle calculation unit 62 causes the reporter 37 to perform a report operation indicating a low sensitivity mode. On the other hand, when the prohibition condition is met or the low sensitivity condition is not met, the target steering angle calculation unit 62 outputs a mode signal Sm, indicating a normal mode, to the protection processing unit 72 and the aforementioned reporter 37. This mode signal Sm is configured so that the target steering angle calculation unit 62 causes the reporter 37 to perform a report operation indicating a normal mode. That is, the target steering angle calculation unit 62 acts as a report control unit.

[0053] Next, we will explain the low sensitivity conditions and the prohibited conditions.

[0054] The target turning angle calculation unit 62 determines that the low sensitivity condition is met if at least one of the following conditions is met.

[0055] (a1) The vehicle speed V is above the high speed determination threshold Vth, and the absolute value of the pole tilt angle θl is below the forward determination threshold θlth.

[0056] (a2) The vehicle speed V is above the high speed determination threshold Vth, and the absolute value of the lateral acceleration GY is below the turning determination threshold GYth.

[0057] (a3) The vehicle speed V is above the high speed determination threshold Vth, and the vertical acceleration GZ is below the tilt determination threshold GZth.

[0058] (a4) Sensitivity switch 14 is in the ON state.

[0059] (a5) The gear lever is in reverse position R.

[0060] In addition, the high-speed determination threshold Vth is the vehicle speed V that can be determined as the vehicle traveling at high speed, and is preset. The forward determination threshold θlth is the lever tilt angle θl that can be determined as the control lever 11 not tilting, and is preset. The turning determination threshold GYth is the lateral acceleration GY that can be determined as the vehicle not turning significantly, and is preset. The tilt determination threshold GZth is the vertical acceleration GZ that can be determined as the vehicle traveling on an uneven road, and is preset to a negative value.

[0061] As in (a1) to (a3), the low sensitivity condition includes a condition based on a comparison with a threshold value representing the vehicle's driving state. In (a1) to (a3), vehicle speed V, lateral acceleration GY, and vertical acceleration GZ are driving parameters. As in (a4), the low sensitivity condition includes a condition based on the on or off state of sensitivity switch 14. As in (a5), the low sensitivity condition includes a condition such as the vehicle being in reverse.

[0062] The target turning angle calculation unit 62 determines that the prohibition condition is met if the following conditions are met.

[0063] (b1) The operating speed ωl of the control lever 11 is above the emergency operation judgment threshold ωlth.

[0064] The emergency operation determination threshold ωlth is the operating speed ωl at which the driver can determine that they have performed an emergency operation on the control lever 11, and it is preset. In this embodiment, the target steering angle calculation unit 62 calculates the operating speed ωl by differentiating the lever tilt angle θl. In other embodiments, a speed sensor may be provided in the operation unit 4, and the operating speed ωl may be input from the speed sensor.

[0065] Next, combined Figure 4 The flowchart shown illustrates an example of the processing order of the target steering angle calculation unit 62 in calculating the target steering angle θp*.

[0066] As shown in the figure, if the target steering angle calculation unit 62 acquires various state variables (step 101), it calculates the operating speed ωl of the control stick 11 (step 102). Next, the target steering angle calculation unit 62 determines whether the operating speed ωl is above the emergency operation judgment threshold ωlth (step 103). If the operating speed ωl is above the emergency operation judgment threshold ωlth (step 103: yes), the target steering angle θp* is calculated using the normal mapping table 81 (step 104). Then, the mode signal Sm, which indicates the normal mode, is output (step 105), and the process ends. The process in step 103 is equivalent to the prohibition judgment process, the process in step 104 is equivalent to the normal operation process, and the process in step 105 is equivalent to the report process.

[0067] On the other hand, if the operating speed ωl is less than the emergency operation determination threshold ωlth (step 103: No), the target turning angle calculation unit 62 determines whether the sensitivity switch 14 is in the on state (step 106). If the sensitivity switch 14 is in the on state (step 106: Yes), the target turning angle θp* is calculated using the low sensitivity mapping table 82 (step 107). Then, the mode signal Sm, which indicates the low sensitivity mode, is output (step 108), and the process ends. The process in step 107 is equivalent to the low sensitivity calculation process, and the process in step 108 is equivalent to the report process.

[0068] When the sensitivity switch 14 is off (step 106: No), the target steering angle calculation unit 62 determines whether the position signal Sp indicates the reverse gear position R (step 109). If the position signal Sp indicates the reverse gear position R (step 109: Yes), proceed to steps 107 and 108 for corresponding processing.

[0069] If the position signal Sp is not in reverse gear position R (step 109: No), the target steering angle calculation unit 62 determines whether the vehicle speed V is above the high-speed determination threshold Vth (step 110). If the vehicle speed V is above the high-speed determination threshold Vth (step 110: Yes), it determines whether the absolute value of the lever tilt angle θl is below the forward determination threshold θlth (step 111). If the absolute value of the lever tilt angle θl is greater than the forward determination threshold θlth (step 111: No), it determines whether the absolute value of the lateral acceleration GY is below the turning determination threshold GYth (step 112). If the absolute value of the lateral acceleration GY is greater than the turning determination threshold GYth (step 112: No), it determines whether the vertical acceleration GZ is below the negative tilt determination threshold GZth (step 113). If the vertical acceleration GZ is greater than the negative tilt determination threshold GZth (step 113: No), it proceeds to steps 104 and 105 for corresponding processing. In addition, if the vehicle speed V is less than the high-speed determination threshold Vth (step 110: No), the process moves to steps 104 and 105 for corresponding processing.

[0070] If the absolute value of the pole tilt angle θl is below the forward determination threshold θlth (step 111: Yes), the target steering angle calculation unit 62 moves to steps 107 and 108 for corresponding processing. Similarly, if the absolute value of the lateral acceleration GY is below the turning determination threshold GYth (step 112: Yes), or if the vertical acceleration GZ is below the negative tilt determination threshold GZth (step 113: Yes), the unit also moves to steps 107 and 108 for corresponding processing. The processing in steps 109 to 113 is equivalent to low-sensitivity determination processing.

[0071] (Protection and Treatment Department 72)

[0072] Next, the protection processing of the differential Δθp performed by the protection processing unit 72 will be explained.

[0073] like Figure 2 As shown, the protection processing unit 72 performs upper limit speed calculation processing to set the upper limit speed of the steering wheel 3. In addition, the protection processing unit 72 performs difference upper limit value calculation processing to calculate the difference upper limit value Δθlim corresponding to the upper limit speed, and performs protection processing to limit the difference Δθp based on the comparison between the difference Δθp and the difference upper limit value Δθlim.

[0074] In this embodiment, the protection processing unit 72 calculates the upper limit speed based on the vehicle's driving state and the operating state of the control lever 11 during the upper limit speed calculation process.

[0075] In detail, even if the lever tilt angle θl remains constant, sometimes the mode of the target steering angle calculation unit 62 changes, thus changing the target steering angle θp*. Based on this situation, the protection processing unit 72 calculates the upper limit speed (transition limit speed) when migrating from the normal mode to the low-sensitivity mode, and the upper limit speed (recovery limit speed) when returning from the low-sensitivity mode to the normal mode, based on the vehicle speed V. That is, the transition limit speed and the recovery limit speed are set separately. The protection processing unit 72 determines whether it is switching from the normal mode to the low-sensitivity mode or vice versa based on the mode signal Sm.

[0076] The protection processing unit 72 calculates the upper limit speed for steering input (i.e., the steering upper limit speed) and the upper limit speed for return input (i.e., the return upper limit speed) based on the vehicle speed V. That is, the steering upper limit speed and the return upper limit speed are set separately. Steering input is an operation that increases the absolute value of the lever angle θl, and return input is an operation that decreases the absolute value of the lever angle θl. In this embodiment, the protection processing unit 72 determines whether to perform a steering input or a return input based on the change in the absolute value of the lever angle θl. In other embodiments, the protection processing unit 72 may also determine whether to perform a steering input or a return input based on the change in the absolute value of the steering angle θp.

[0077] Furthermore, the protection processing unit 72 calculates the upper limit speed in cases other than those described above, which is the general upper limit speed.

[0078] If the protection processing unit 72 determines that it has switched from the normal mode to the low-sensitivity mode, it calculates the upper limit migration speed based on the vehicle speed V. Although the protection processing unit 72 of this embodiment performs the calculation in a manner that the higher the vehicle speed V, the lower the upper limit migration speed, it can also perform the calculation in a manner that the higher the vehicle speed V, the higher the upper limit migration speed. For example, the protection processing unit 72 has a mapping table or function that represents the relationship between the vehicle speed V and the upper limit migration speed, and calculates the upper limit migration speed corresponding to the vehicle speed V by referring to the mapping table or function.

[0079] If the protection processing unit 72 determines that it has switched from low-sensitivity mode to normal mode, it calculates the recovery upper limit speed based on the vehicle speed V. While the protection processing unit 72 in this embodiment calculates the recovery upper limit speed in a manner where a higher vehicle speed V results in a lower recovery upper limit speed, it can also calculate it in a manner where a higher vehicle speed V results in a higher recovery upper limit speed. Furthermore, when the vehicle speed V is the same, the protection processing unit 72 can set the recovery upper limit speed to a value greater than the migration upper limit speed, or it can set the recovery upper limit speed to a value less than the migration upper limit speed. Moreover, similar to the calculation of the migration upper limit speed, the protection processing unit 72 uses a mapping table or a function to calculate the recovery upper limit speed.

[0080] If the protection processing unit 72 determines that a steering wheel operation has been performed, it calculates the upper limit speed for steering wheel operation based on the vehicle speed V. While the protection processing unit 72 in this embodiment calculates the upper limit speed for steering wheel operation in a manner where a higher vehicle speed V results in a lower upper limit speed, it can also calculate it in a manner where a higher vehicle speed V results in a higher upper limit speed for steering wheel operation. Similar to the case of calculating the upper limit speed, the protection processing unit 72 uses a mapping table or a function to calculate the upper limit speed for steering wheel operation.

[0081] If the protection processing unit 72 determines that a wheel return operation has been performed, it calculates the upper limit speed for wheel return based on the vehicle speed V. While the protection processing unit 72 in this embodiment calculates the upper limit speed for wheel return as the vehicle speed V increases, it can also calculate it as the upper limit speed for wheel return increases as the vehicle speed V increases. Furthermore, when the vehicle speed V is the same, the protection processing unit 72 can set the upper limit speed for wheel return to a value greater than the upper limit speed for steering, or it can set the upper limit speed for wheel return to a value less than the upper limit speed for steering. Similar to the calculation of the upper limit speed for steering shift, the protection processing unit 72 calculates the upper limit speed for wheel return.

[0082] If the protection processing unit 72 determines that the mode of the target steering angle calculation unit 62 is maintained and neither a steering wheel turn nor a steering wheel return operation is performed, then it calculates the general upper limit speed based on the vehicle speed V. While the protection processing unit 72 in this embodiment sets the general upper limit speed lower as the vehicle speed V increases, it can also set the general upper limit speed higher as the vehicle speed V increases. Similar to the case of calculating the migration upper limit speed, the protection processing unit 72 calculates the general upper limit speed.

[0083] Furthermore, in the differential upper limit value calculation process, the protection processing unit 72 calculates the differential upper limit value Δθlim corresponding to the calculated upper limit speed, namely the migration upper limit speed, recovery upper limit speed, steering upper limit speed, return upper limit speed, or general upper limit speed. For example, the protection processing unit 72 has a mapping table or function that represents the relationship between the upper limit speed and the differential upper limit value Δθlim, and by referring to the same mapping table or function, it calculates the differential upper limit value Δθlim corresponding to the calculated upper limit speed.

[0084] In the protection processing, the protection processing unit 72 compares the absolute value of the input difference Δθp with the calculated upper limit value of the difference Δθlim. If the absolute value of the difference Δθp is less than or equal to the upper limit value Δθlim, the protection processing unit 72 maintains the input difference Δθp and outputs it to the F / B control unit 73 as the processed difference Δθpg. On the other hand, if the absolute value of the difference Δθp is greater than the upper limit value Δθlim, the protection processing unit 72 maintains the sign of the input difference Δθp and outputs the value whose absolute value is equal to the upper limit value Δθlim as the processed difference Δθpg to the F / B control unit 73.

[0085] In this embodiment, the protection processing unit 72 performs protection processing using a difference upper limit value Δθlim corresponding to the upper limit of the migration speed when switching from a normal mode to a low sensitivity mode during a rotary or return operation. However, in other embodiments, the difference upper limit value Δθlim corresponding to the upper limit of the rotary or return speed may also be used for protection processing in such cases. Furthermore, in this embodiment, the protection processing unit 72 performs protection processing using a difference upper limit value Δθlim corresponding to the upper limit of the recovery speed when switching from a low sensitivity mode to a normal mode during a rotary or return operation. However, in other embodiments, the difference upper limit value Δθlim corresponding to the upper limit of the rotary or return speed may also be used for protection processing in such cases.

[0086] Next, according to Figure 5 as well as Figure 6 The flowchart shown illustrates an example of the processing sequence in which the protection processing unit 72 performs protection processing on the difference Δθp.

[0087] like Figure 5 As shown, if the protection processing unit 72 acquires various state variables (step 201), it calculates the upper limit speed (step 202). The calculation of the upper limit speed is based on... Figure 6 The process is performed according to the flowchart shown. Step 202 is equivalent to the upper limit speed calculation process.

[0088] like Figure 6 As shown, the protection processing unit 72 determines whether the mode has changed from the normal mode to the low sensitivity mode based on the mode signal Sm (step 301). If the mode has changed from the normal mode to the low sensitivity mode (step 301: Yes), the upper limit speed for migration is calculated based on the vehicle speed V (step 302).

[0089] If there is no change from the normal mode to the low-sensitivity mode (step 301: No), the protection processing unit 72 determines whether to change from the low-sensitivity mode to the normal mode (step 303). If there is a change from the low-sensitivity mode to the normal mode (step 303: Yes), the upper limit speed is calculated based on the vehicle speed V (step 304).

[0090] If the system does not change from low-sensitivity mode to normal mode (step 303: No), the protection processing unit 72 determines whether a steering operation has been performed based on the change in the absolute value of the lever tilt angle θl (step 305). If a steering operation has been performed (step 305: Yes), the upper limit speed for steering is calculated based on the vehicle speed V (step 306).

[0091] If no wheel-turning operation was performed (step 305: No), the protection processing unit 72 determines whether a wheel-returning operation was performed (step 307). If a wheel-returning operation was performed (step 307: Yes), the upper limit speed for wheel-returning is calculated based on the vehicle speed V (step 308). On the other hand, if no wheel-returning operation was performed (step 307: No), the general upper limit speed is calculated based on the vehicle speed V (step 309).

[0092] return Figure 5 If the protection processing unit 72 calculates the upper limit speed in step 202, it calculates the difference upper limit value Δθlim corresponding to the calculated upper limit speed (step 203). The processing in step 203 is equivalent to the difference upper limit value calculation processing.

[0093] Next, it is determined whether the absolute value of the difference Δθp obtained in step 201 is below the upper limit of the difference Δθlim (step 204). If the absolute value of the difference Δθp is below the upper limit of the difference Δθlim (step 204: Yes), the difference Δθp is maintained and output as the difference Δθpg after protection processing (step 205), and the process ends. On the other hand, if the absolute value of the difference Δθp is greater than the upper limit of the difference Δθlim (step 204: No), the sign of the obtained difference Δθp is maintained, and the value whose absolute value is equal to the upper limit of the difference Δθlim is output as the difference Δθpg after protection processing (step 206), and the process ends. The processing in steps 205 and 206 is equivalent to protection processing.

[0094] Next, the function and effects of this implementation method will be explained.

[0095] (1) When the low-sensitivity condition is met, the target steering angle calculation unit 62 performs low-sensitivity calculation processing based on the lever tilt angle θl to calculate the target steering angle θp*, which is smaller in absolute value than the target steering angle θp* calculated by normal calculation processing. Therefore, when the low-sensitivity condition is met, the calculation is performed in a way that the target steering angle θp* is smaller than usual. As a result, the angle ratio α becomes smaller, so it is easier to fine-tune the steering angle θi of the steering wheel 3. Since it is easier to fine-tune the steering angle θi, it is easier to perform operations such as preventing the vehicle from leaving the lane while moving forward, and operations when driving on a gentle, bumpy road.

[0096] (2) The target steering angle calculation unit 62 determines whether the low sensitivity condition is met based on the comparison between the driving parameters representing the vehicle's driving state and the threshold value. Therefore, the angle ratio α can be appropriately reduced according to the vehicle's driving state.

[0097] (3) The steering control device 2 has a sensitivity switch 14 operated by the driver. The target steering angle calculation unit 62 determines whether a low sensitivity condition is met based on the on or off state of the sensitivity switch 14. Therefore, the angle ratio α can be reduced according to the driver's intention.

[0098] (4) The target steering angle calculation unit 62 determines that the low sensitivity condition is met when the vehicle is in reverse. As a result, the angle is smaller than α when the vehicle is in reverse, so the vehicle's movement is less likely to be disordered when it is in reverse.

[0099] (5) The target steering angle calculation unit 62 also performs prohibition determination processing to determine whether the prohibition condition is met. If the prohibition condition is met, even if the low sensitivity condition is met, the low sensitivity calculation processing is not performed, and the normal calculation processing is performed instead. Therefore, if the prohibition condition is met, the angle ratio α will not become smaller, and the steering wheel 3 can be turned more significantly. Thus, for example, when avoiding obstacles in front of the vehicle, the steering wheel 3 can be turned smoothly.

[0100] (6) The target turning angle calculation unit 62 determines whether the prohibition condition is met based on whether the operating speed ωl of the control stick 11 is above the emergency operation determination threshold ωlth. In most cases, the operation is performed as quickly as possible when avoiding obstacles. Therefore, for example, when avoiding obstacles, the prohibition angle can be appropriately smaller than α.

[0101] (7) The target steering angle calculation unit 62 includes a memory 62a. The memory 62a stores a normal mapping table 81 and a low-sensitivity mapping table 82 that represent the relationship between the lever tilt angle θl and the target steering angle θp*. The absolute value of the change in the target steering angle θp* relative to the change in lever tilt angle θl and vehicle speed V in the low-sensitivity mapping table 82 is set to be smaller than that in the normal mapping table 81. The normal calculation process uses the normal mapping table 81 to calculate the target steering angle θp* based on the lever tilt angle θl. The low-sensitivity calculation process uses the low-sensitivity mapping table 82 to calculate the target steering angle θp* based on the lever tilt angle θl. That is, the target steering angle calculation unit 62 switches between the mapping tables used in the normal calculation process and the low-sensitivity calculation process. As a result, the target steering angle calculation unit 62 can easily calculate the target steering angle θp* with an absolute value smaller than that calculated by the normal calculation process in the low-sensitivity mode.

[0102] (8) The control signal generation unit 63 generates a control signal Mt that controls the steering speed of the steering wheel 3 to be below the upper limit speed. As a result, since the sudden change in steering angle θi is suppressed, the erratic behavior of the vehicle can be suppressed.

[0103] (9) The control signal generation unit 63 includes: a subtractor 71 that calculates the difference between the corresponding steering angle θp and the target corresponding steering angle θp*; a protection processing unit 72 that limits the absolute value of the difference Δθp to below the upper limit value Δθlim corresponding to the upper limit speed; and an F / B control unit 73 that generates a control signal Mt based on the difference after protection processing. According to the above structure, as long as the absolute value of the difference Δθp is limited to below the upper limit value Δθlim, for example, compared with the case of performing speed F / B control, the computational load for setting the steering speed of the steering wheel 3 to below the upper limit speed can be reduced.

[0104] (10) The protection processing unit 72 performs upper limit speed calculation processing based on the vehicle speed V. Here, even if the steering speed is the same, the degree of erratic behavior of the vehicle will vary depending on the vehicle speed V. That is, the higher the vehicle speed V, the more erratic the vehicle's behavior. In this regard, according to the above structure, an appropriate upper limit speed can be set based on the vehicle speed V.

[0105] (11) The protection processing unit 72 sets the migration upper limit speed and the recovery upper limit speed respectively. Therefore, the target steering angle calculation unit 62 can turn the steering wheel 3 caused by switching to normal mode or low sensitivity mode at an appropriate steering speed.

[0106] (12) The protection processing unit 72 sets the upper limit speed for turning the wheel and the upper limit speed for returning the wheel. Therefore, the steering wheel 3 can be turned at an appropriate steering speed according to the turning or returning wheel operation.

[0107] (13) A report unit 37 is connected to the steering control device 1. When the target steering angle calculation unit 62 is in low sensitivity mode, it reports the intention through the report unit 37. Therefore, the driver can easily identify whether it is in low sensitivity mode, that is, whether the angle ratio α has become smaller.

[0108] This embodiment can be modified as follows. This embodiment and the following variations can be combined with each other to the extent that they are not technically contradictory.

[0109] Although the protection processing unit 72 calculates the upper limit speed for turning the wheel and the upper limit speed for returning the wheel separately, it can also calculate a single upper limit speed as the upper limit speed during operation of the control lever 11, without distinguishing between turning and returning the wheel. Furthermore, although the protection processing unit 72 sets separate upper limit speeds for shifting and returning, it can also calculate a single upper limit speed as the upper limit speed during mode changes. Moreover, it can also calculate only the general upper limit speed, regardless of the vehicle's driving state or the operating state of the control lever 11.

[0110] Alternatively, any one of the following speed limits—the migration limit speed, the recovery limit speed, the steering limit speed, the return limit speed, and the general limit speed—can be set as a fixed value that is not calculated by the protection processing unit 72 based on the vehicle speed V, but is instead set as a preset value.

[0111] The control signal generation unit 63 generates a control signal Mt that sets the steering speed of the steering wheel 3 to below the upper limit speed by limiting the absolute value of the difference Δθp to below the upper limit value Δθlim. However, it is not limited to this; it can also generate a control signal Mt that sets the steering speed of the steering wheel 3 to below the upper limit speed by performing speed feedback control. Alternatively, the control signal generation unit 63 can also generate the control signal Mt without considering the steering speed of the steering wheel 3.

[0112] The microcomputer 51 may also lack a steering angle calculation unit 61. In this case, for example, the rotation angle, i.e., the steering angle θp, can be input from a sensor that detects the rotation angle of the pinion shaft 21. This sensor can also detect the rotation angle of the pinion shaft 21 in an absolute angle range exceeding 360°.

[0113] The target steering angle calculation unit 62 calculates a target steering angle θp* with an absolute value smaller than that calculated by the normal calculation process by switching the mapping table used in the normal calculation process and the low-sensitivity calculation process, when the low-sensitivity condition is met. However, it is not limited to this. For example, the target steering angle θp* can be calculated using the normal mapping table 81 in the normal calculation process, and the target steering angle θp* calculated using the normal mapping table 81 can be corrected in the low-sensitivity calculation process, thereby calculating a target steering angle θp* with an absolute value smaller than that target steering angle θp*. As a correction method, for example, a predetermined value can be subtracted from the target steering angle θp* calculated using the normal mapping table 81, or the target steering angle θp* calculated using the normal mapping table 81 can be multiplied by a gain less than "1".

[0114] While the target steering angle calculation unit 62 has a single low-sensitivity mapping table 82, it is not limited to this and may have two or more low-sensitivity mapping tables. For example, when both a first low-sensitivity mapping table and a second low-sensitivity mapping table are provided, the second low-sensitivity mapping table may be set such that the absolute value of the target steering angle θp* relative to the pole tilt angle θl is less than that of the first low-sensitivity mapping table. The target steering angle calculation unit 62 may also be configured such that, for example, when only one of (a1) to (a5) is true, the first low-sensitivity mapping table is used to calculate the target steering angle θp*, and when any two or more of (a1) to (a5) are true, the second low-sensitivity mapping table is used to calculate the target steering angle θp*.

[0115] Blind zones can also be set in the normal mapping table 81 and the low-sensitivity mapping table 82. Specifically, a range is set near zero degrees of the stick tilt angle θl, within which the target steering angle θp* remains zero even as the absolute value of the stick tilt angle θl increases. Furthermore, the normal mapping table 81 and the low-sensitivity mapping table 82 can also be two-dimensional mapping tables representing the relationship between the target steering angle θp* and the stick tilt angle θl. That is, the normal calculation processing and the low-sensitivity calculation processing can also be processes that calculate the target steering angle θp* based solely on the stick tilt angle θl. Additionally, the normal calculation information and the low-sensitivity calculation information do not necessarily have to be mapping tables; for example, they can be functions.

[0116] The target turning angle calculation unit 62 determines whether the low sensitivity condition is true or false by judging conditions (a1) to (a5), but it may also judge only at least one of them. Alternatively, other conditions may be used to determine whether the low sensitivity condition is true or false.

[0117] The conditions (a1) to (a5) can be appropriately changed. For example, in condition (a2), in addition to determining whether the absolute value of the lateral acceleration GY is below the turning threshold GYth, it is also possible to determine whether the absolute value of the vehicle's yaw rate is below the turning threshold GYth. Furthermore, the high-speed thresholds Vth in (a1) to (a3) ​​can also be different values.

[0118] In order to determine whether the prohibition condition is met, the target steering angle calculation unit 62 determines the condition (b1), but it can also use other conditions to make the determination, either in addition to or in place of the condition. Such other conditions could be, for example, the input of a signal indicating that the driver has performed a sudden braking operation. Alternatively, the target steering angle calculation unit 62 may not determine whether the prohibition condition is met.

[0119] The processing order performed by the target-to-corresponding angle calculation unit 62 is not limited to Figure 4 The order shown can be changed appropriately. For example, after obtaining various state variables (step 101), the target turning angle θp* can be calculated immediately using the normal mapping table 81 (step 104), and if the low sensitivity condition is met, the calculated target turning angle θp* can be changed to a value based on the low sensitivity mapping table 82. Similarly, the processing order of the protection processing unit 72 is not limited to... Figure 5 as well as Figure 6 The order shown can also be changed appropriately.

[0120] In the above embodiment, the convertible value that can be converted into the steering angle θi of the steering wheel 3 is the rotation angle of the pinion shaft 21, but it is not limited to this. For example, the stroke of the rack shaft 22 or the steering angle θi itself can also be convertible values.

[0121] The sensitivity switch 14 can also be a type of switch that only switches to the on state during the driver's pressing. Alternatively, the sensitivity switch 14 can also be a dial-type multi-stage switch capable of switching between three or more states. Such a multi-stage switch is suitable for situations where the target steering angle calculation unit 62 has multiple low-sensitivity mapping tables. Furthermore, the steering control device 2 may not include the sensitivity switch 14.

[0122] The microcomputer 51 may also have a separate report control unit that performs the same determination of low sensitivity conditions and prohibition conditions as the target turning angle calculation unit 62, and this report control unit reports the intention of the low sensitivity mode through the reporter 37. Alternatively, the microcomputer 51 may choose not to report the intention of the low sensitivity mode.

[0123] Although the control lever 11 is supported by the base 12 and can tilt, it is not limited to this; for example, it can also be supported by the base 12 and can slide. In this case, the amount of operation performed by the driver is represented by the amount of sliding of the control lever 11. In addition to controlling the steering angle θi of the steering wheel 3, the control lever 11 can also be used to control the vehicle's drive / brake.

[0124] The operating unit 4 may also include a motor and / or a spring that applies a reaction force to the control lever 11 in response to the driver's operation. In the structure where the reaction force is applied by a motor, the lever tilt angle θl can be detected based on the rotation angle of the motor. Furthermore, in addition to the control lever 11, the operating unit 4 may also include a steering wheel operated by the driver. Although the steering control device 2 is a non-linked structure that separates the power transmission between the operating unit 4 and the steering unit 5, it is not limited to this. When a steering wheel is included, the steering control device 2 may also be a structure that can separate the power transmission between the operating unit 4 and the steering unit 5 via a clutch.

[0125] While the steering actuator 31 transmits the rotation of the steering motor 32 to the ball screw mechanism 35 via the belt mechanism 34, it is not limited to this. For example, the steering actuator 31 may also be configured to transmit the rotation of the steering motor 32 to the ball screw mechanism 35 via a gear mechanism. Alternatively, the steering actuator 31 may be configured such that the steering motor 32 directly rotates the ball screw mechanism 35. Furthermore, the steering unit 5 may be configured to have a structure with a second rack and pinion mechanism, so that the steering actuator 31 applies steering force to the steering unit 5 by converting the rotation of the steering motor 32 into the reciprocating movement of the rack shaft 22 through the second rack and pinion mechanism.

[0126] Next, the technical concepts that can be grasped based on the above implementation methods and variations are supplemented as follows.

[0127] (a) The aforementioned low sensitivity condition may also include a forward condition, which includes the vehicle speed, which is the aforementioned driving parameter, being above the high speed determination threshold, and the absolute value of the aforementioned operation amount being below the forward determination operation amount.

[0128] (b) The aforementioned low sensitivity condition may also include a turning condition, which includes the vehicle speed, which is the aforementioned driving parameter, being above the high speed determination threshold, and the absolute value of the yaw rate or lateral acceleration of the aforementioned vehicle, which is the aforementioned driving parameter, being below the turning determination threshold.

[0129] (c) The above-mentioned vehicle's vertical acceleration can also detect the upward acceleration as a positive value and the downward acceleration as a negative value. The above-mentioned low sensitivity condition can also include the inclined road condition, which includes the vehicle speed, which is the above-mentioned driving parameter, being above the high speed determination threshold and the above-mentioned vertical acceleration, which is the above-mentioned driving parameter, being below the inclination determination threshold.

Claims

1. A steering control device for controlling the steering control of a vehicle, wherein, The aforementioned steering control device has a structure that separates the power transmission path between the operating unit with the operating lever and the steering unit configured to steer the steering wheels. The aforementioned steering control device includes: The target steering correspondence value calculation unit is configured to calculate a target value, i.e., the target steering correspondence value, that can be converted into a convertible value of the steering angle of the aforementioned steering wheel; and The control signal generation unit is configured to generate a control signal that causes the steering unit to operate based on the aforementioned target steering value. The aforementioned target is redirected to the corresponding value arithmetic unit, which is configured to perform the following processing: Low sensitivity determination process for determining whether the low sensitivity condition that reduces the change in steering angle relative to the change in the operation amount of the above-mentioned control lever is met. If the aforementioned low-sensitivity condition is not met, the normal calculation process is performed to calculate the target turning value based on the aforementioned operation amount. as well as When the aforementioned low-sensitivity condition is met, a low-sensitivity calculation process is performed based on the aforementioned operation amount to calculate the target turning value, which has an absolute value smaller than the target turning value calculated by the aforementioned normal calculation process. The above-mentioned target-directed corresponding value calculation unit is configured as follows It also performs a prohibition determination process to determine whether the prohibition condition that would prevent a decrease in the change in the steering angle relative to the change in the aforementioned operational quantity is met. If the above prohibition conditions are met, even if the above low sensitivity conditions are met, the above low sensitivity operation processing will not be performed and the above normal operation processing will be performed instead.

2. The steering control device according to claim 1, wherein, The aforementioned low sensitivity condition includes a condition based on a comparison of the driving parameters representing the driving state of the vehicle with the magnitude of a threshold.

3. The steering control device according to claim 1 or 2, wherein, The aforementioned steering control device has a sensitivity switch configured to be operated by the driver. The aforementioned low sensitivity conditions include conditions based on the on or off state of the aforementioned sensitivity switch.

4. The steering control device according to claim 1 or 2, wherein, The aforementioned low sensitivity condition includes the condition that the vehicle is in reverse.

5. The steering control device according to claim 1 or 2, wherein, The aforementioned prohibition conditions include situations where the operating speed of the aforementioned control lever exceeds the emergency operation determination threshold.

6. The steering control device according to claim 1 or 2, wherein, The aforementioned target-oriented value calculation unit has memory. The aforementioned memory stores general computational information and low-sensitivity computational information representing the relationship between the aforementioned operational quantities and the corresponding values ​​of the aforementioned target orientation. The absolute value change of the target orientation corresponding to the change in the change of the aforementioned operational quantity in the aforementioned low-sensitivity calculation information is set to be smaller than that in the aforementioned normal calculation information. The above-described general computational processing involves using the aforementioned general computational information to calculate the target direction corresponding to the value based on the aforementioned operational quantities. The aforementioned low-sensitivity computation processing uses the aforementioned low-sensitivity computation information to calculate the corresponding value of the target orientation based on the aforementioned operational quantity.

7. The steering control device according to claim 1 or 2, wherein, The control signal generation unit is configured to generate a control signal that controls the steering speed of the steering wheel to be below the upper limit speed.

8. The steering control device according to claim 7, wherein, The aforementioned control signal generation unit includes: The subtractor is configured to calculate the difference between the actual value of the aforementioned convertible value, i.e., the steering corresponding value, and the target steering corresponding value. The protection processing unit is configured to perform protection processing that limits the absolute value of the aforementioned difference to below a difference upper limit value corresponding to the aforementioned upper limit speed; and The feedback control unit is configured to generate the control signal based on the differential signal after the protection processing described above.

9. The steering control device according to claim 8, wherein, The aforementioned protection processing unit is configured to also perform upper limit speed calculation processing based on vehicle speed to calculate the upper limit speed.

10. The steering control device according to claim 7, wherein, The aforementioned target turning value calculation unit includes a normal mode that calculates the target turning value by executing the aforementioned normal calculation process, and a low-sensitivity mode that calculates the target turning value by executing the aforementioned low-sensitivity calculation process. The aforementioned upper limit speed includes the upper limit speed for the transition from the aforementioned normal mode to the aforementioned low sensitivity mode, i.e., the transition upper limit speed, and the upper limit speed for the recovery from the aforementioned low sensitivity mode back to the aforementioned normal mode, i.e., the recovery upper limit speed. The aforementioned migration upper limit speed and the aforementioned recovery upper limit speed are set separately.

11. The steering control device according to claim 7, wherein, The aforementioned upper limit speed includes the upper limit speed for a turn operation when the absolute value of the aforementioned operation amount increases, i.e., the upper limit speed for a turn operation, and the upper limit speed for a return operation when the absolute value of the aforementioned operation amount decreases, i.e., the upper limit speed for a return operation. The upper limit speeds for turning the wheel and returning the wheel are set separately.

12. The steering control device according to claim 1 or 2, wherein, The aforementioned steering control device is connected to a transmitter. The aforementioned steering control device further includes a reporting control unit, which is configured to report, via the reporter, that the target steering corresponding value calculation unit is in a low-sensitivity mode when the target steering corresponding value is calculated by executing the low-sensitivity calculation process.

13. A steering control method for controlling a vehicle's steering mechanism, wherein, The aforementioned steering control device has a structure that separates the power transmission path between the operating unit with the operating lever and the steering unit configured to steer the steering wheels. The above-mentioned steering control method includes: The steps for calculating the target value, i.e., the target steering angle corresponding to the aforementioned steering wheel, that can be converted into a convertible value; and The step of generating a control signal to activate the steering unit based on the aforementioned target steering value. The steps for calculating the target-to-corresponding value mentioned above include performing the following processing: Low sensitivity determination process for determining whether the low sensitivity condition that reduces the change in steering angle relative to the change in the operation amount of the above-mentioned control lever is met. If the aforementioned low-sensitivity condition is not met, the normal calculation process is performed to calculate the target turning value based on the aforementioned operation amount. as well as When the aforementioned low-sensitivity condition is met, a low-sensitivity calculation is performed based on the aforementioned operation amount to calculate the target orientation value, which is smaller in absolute value than the target orientation value calculated through the aforementioned normal calculation process. The steps for calculating the target turning value mentioned above include: It also performs a prohibition determination process to determine whether the prohibition condition that would prevent a decrease in the change in the steering angle relative to the change in the aforementioned operational quantity is met. If the above prohibition conditions are met, even if the above low sensitivity conditions are met, the above low sensitivity operation processing will not be performed and the above normal operation processing will be performed instead.

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