JP2024030402A - Steering control device - Google Patents

Abstract

To provide a steering control device capable of suppressing steering of a steering wheel by a driver, while notifying that the processing for increasing the output of a steering motor is being executed.SOLUTION: A steering control device includes: a steering control section 36 which calculates a torque command value Tp* to a steering motor according to a steering state of a steering wheel; and a reaction control section 27 which calculates a steering reaction command value to a reaction motor. The reaction control section 36 executes boost-increase processing for increasing the torque command value Tp* to a value larger than an original value according to a steering state of the steering wheel under a circumstance in which a steering force is easy to lack. During the period at which the boost-increase processing is being executed, the reaction control section 27 executes the processing for increasing the steering reaction command value to a value larger than an original value according to a steering state of the steering wheel.SELECTED DRAWING: Figure 3

Description

The present invention relates to a steering control device.

Conventionally, there is a so-called steer-by-wire type steering device in which power transmission between a steering wheel and steered wheels is separated. The steering device includes a reaction force motor that is a source of a steering reaction force applied to a steering shaft, and a steering motor that is a source of a steering force that turns steered wheels. When the vehicle is running, the control device of the steering device generates a steering reaction force by controlling the power supply to the reaction force motor, and steers the steered wheels by controlling the power supply to the steering motor.

In steer-by-wire type steering devices, excessive axial force may be generated in the steered shaft due to high friction on the road surface. Depending on the magnitude of the axial force generated on the steering shaft, there is a possibility that the steering force, which is the output of the steering motor, may be insufficient. In this case, since it becomes difficult to sufficiently turn the steered wheels in response to the steering wheel, the driver may feel uncomfortable.

Therefore, for example, the control device disclosed in Patent Document 1 increases the output of the steering motor when an excessive axial force is likely to be generated on the steering shaft. Specifically, the control device increases the command value for the steering motor to a value larger than the original command value according to the steering state of the steering wheel. Therefore, the steering motor generates a steering force larger than a normal steering force according to a command value calculated according to the steering state of the steering wheel.

Japanese Patent Application Publication No. 2022-49969

According to the control device of Patent Document 1, the steered wheels can be smoothly steered without running out of steering force. However, for example, if the output of the steering motor continues to increase, there is a risk that the steering motor or the inverter that supplies electric power to the steering motor may become overheated.

A steering control device that can solve the above problem is a steering shaft that steers steered wheels of a vehicle, and includes a steering shaft configured to separate power transmission from the steering wheel, and a steering shaft that steers steered wheels of a vehicle. a reaction force motor that generates a steering reaction force applied to a wheel, and a steering motor that generates a steering force that is a torque applied to the steering shaft to steer the steered wheels. The steering device provided is the control target. The steering control device includes a control unit configured to calculate a first command value for the steering motor and a second command value for the reaction force motor according to a steering state of the steering wheel. ing. The control unit performs a first process for increasing the first command value to a value larger than an original value according to a steering state of the steering wheel when the steering force is likely to be insufficient. and a second process for increasing the second command value to a value larger than the original value according to the steering state of the steering wheel during the period when the first process is executed. It is configured as follows.

According to this configuration, in preparation for a situation where the steering force is insufficient, in a situation where the steering force is likely to be insufficient, the first command value for the steering motor is set to the original value according to the steering state of the steering wheel. A first process is performed to increase the value to a value greater than . Therefore, through execution of the first process, the steering motor generates a steering force larger than the normal steering force according to the first command value calculated according to the steering state of the steering wheel. By increasing the steering force generated by the steering motor in advance in preparation for a situation where the steering force is insufficient, even if a large axial force is generated on the steering shaft, the steering force will not be insufficient. The steered wheels can be turned smoothly without any problems.

Furthermore, during the period in which the first process is executed, a second process is executed to increase the third command value for the reaction force motor to a value larger than the original value according to the steering state of the steering wheel. . Therefore, through execution of the second process, the reaction force motor generates a steering reaction force that is larger than the normal steering reaction force according to the second command value calculated according to the steering state of the steering wheel. By feeling a response through the steering wheel, the driver of the vehicle can recognize that the first process is being executed, that is, that the steering force has increased compared to normal. becomes. Further, since a steering reaction force larger than a normal steering reaction force is applied to the steering wheel, active steering of the steering wheel by the driver is suppressed. Therefore, overheating of the steering motor and the like can be suppressed.

In the above steering control device, the control unit is configured to determine that the steering force is likely to be insufficient when the vehicle speed is in an extremely low speed range and the steering wheel is being steered. Good too.

When the steering wheel is steered while the vehicle is running at an extremely low speed range, excessive axial force is likely to be generated on the steering shaft. Therefore, by configuring the control unit to determine that when the vehicle speed is in an extremely low speed range and the steering wheel 11 is being steered, the steering force is likely to be insufficient, the control unit can execute the first process at an appropriate timing.

In the above steering control device, as the second process, the control unit multiplies the original second command value according to the steering state of the steering wheel by a gain or adds an additional value. It may be configured to do so.

According to this configuration, the second command value is adjusted to the steering state of the steering wheel by multiplying the original second command value corresponding to the steering state of the steering wheel by a gain or adding an additional value. It can be increased to a value larger than the original value depending on the value.

In the above steering control device, when executing the first process, the control unit determines the degree of increase in the first command value when the steering wheel is turned back. It may be configured to increase the degree of increase in the first command value when steering is performed.

The steering force required when the cut-in steering is performed is larger than the steering force required when the cut-back steering is performed. This is because, for example, when reverse steering is performed, self-aligning torque is applied. For this reason, it can be said that when turning steering is performed, the steering force is more likely to be insufficient than when turning back steering is performed. Therefore, when executing the first process, the degree of increase in the first command value when the steering wheel is turned in is compared to the degree of increase in the first command value when the steering wheel is turned back. It is preferable to make it larger than the degree.

In the above steering control device, as the first process, the control unit multiplies the original first command value according to the steering state of the steering wheel by a gain or adds an additional value. It may be configured to do so.

According to this configuration, the first command value is adjusted to the steering state of the steering wheel by multiplying the gain or adding an additional value to the original first command value corresponding to the steering state of the steering wheel. It can be increased to a value larger than the original value depending on the value.

In the above steering control device, the control unit, as the first process, multiplies a limit value that limits a range of change of the first command value by a gain or adds an additional value. , the change range of the first command value may be expanded.

According to this configuration, when the steering force is likely to be insufficient, the range of change of the first command value for the steering motor is expanded beyond the limit value through execution of the first process. be done. Therefore, even if a first command value exceeding the original limit value is calculated due to generation of excessive axial force, for example, this first command value is allowed. The steering motor generates a larger steering force in response to the first command value that exceeds the original limit value. By expanding the range of change of the first command value in advance in preparation for a situation where the steering force is insufficient, even if a large axial force is generated on the steering shaft, the steering force will not be insufficient. The steered wheels can be smoothly steered.

According to the steering control device of the present invention, it is possible to suppress steering of the steering wheel by the driver while notifying that the process for increasing the output of the steering motor is being executed.

FIG. 1 is a configuration diagram of a steering device equipped with a steering control device according to a first embodiment. FIG. 1 is a block diagram of a steering control device according to a first embodiment. (a) is a block diagram showing a part of the steering control section according to the first embodiment, and (b) is a block diagram showing a part of the steering control section according to the second embodiment. (a) is a timing chart showing an example of a change in the turning angle over time according to the first embodiment, (b) is a timing chart showing an example of a change in the turning angular velocity over time, and (c) is a timing chart showing an example of a change in the turning angle over time. A timing chart showing an example of a change over time; (d) is a timing chart showing an example of a change over time in a boost-up state. (a) is a block diagram showing a part of a steering control section according to a third embodiment, and (b) is a block diagram showing a part of a steering control section according to a fourth embodiment.

<First embodiment>
A first embodiment of a steering control device will be described below. The steering control device is mounted on a steer-by-wire type steering device.

<Configuration of steering device 10>
First, the configuration of the steering device 10 will be explained.
As shown in FIG. 1, the vehicle steering device 10 includes a reaction force unit 20 that applies a steering reaction force to the steering wheel 11 of the vehicle, and a steering unit 30 that turns the steered wheels 12 of the vehicle. . The steering reaction force refers to a torque that acts in a direction opposite to the direction in which the steering wheel 11 is operated by the driver. By applying a steering reaction force to the steering wheel 11, it is possible to give the driver an appropriate feeling of response.

The reaction force unit 20 includes a steering shaft 21 to which the steering wheel 11 is connected, a reaction motor 22, a speed reduction mechanism 23, a rotation angle sensor 24, a torque sensor 25, and a reaction force control section 27.

The reaction force motor 22 is a source of steering reaction force. As the reaction motor 22, for example, a three-phase brushless motor is employed. The reaction motor 22 is connected to the steering shaft 21 via a speed reduction mechanism 23. The torque generated by the reaction force motor 22 is applied to the steering shaft 21 as a steering reaction force.

The rotation angle sensor 24 is provided on the reaction force motor 22. The rotation angle sensor 24 detects the rotation angle _θa of the reaction force motor 22.
Torque sensor 25 is provided at a portion of steering shaft 21 between deceleration mechanism 23 and steering wheel 11 . The torque sensor 25 detects the steering torque T _h applied to the steering shaft 21 through a rotational operation of the steering wheel 11 .

The reaction force control section 27 has a processing circuit including any one of the following three configurations C1, C2, and C3.
C1. One or more processors that operate according to a computer program that is software. The processor includes a CPU (central processing unit) and memory.

C2. One or more specialized hardware circuits, such as an application specific integrated circuit (ASIC), that perform at least some of the various processes. ASIC includes a CPU and memory.

C3. A hardware circuit that combines configurations C1 and C2.
Memory is a medium readable by a computer (in this case, a CPU), and stores a program that describes processing or instructions for the computer. Memory includes RAM (random access memory) and ROM (read only memory). The CPU executes various types of control by executing programs stored in the memory at predetermined calculation cycles.

The reaction force control unit 27 calculates a steering angle _{θ s} that is the rotation angle of the steering shaft 21 based on the rotation angle θ _a of the reaction force motor 22 detected through the rotation angle sensor 24 . The reaction force control unit 27 counts the number of revolutions with the motor center point as a reference. The motor midpoint is the rotation angle _θa of the reaction force motor 22 corresponding to the steering neutral position of the steering wheel 11, and is stored in the reaction force control unit 27 as steering angle midpoint information. The reaction force control unit 27 calculates an integrated angle that is an angle obtained by integrating the rotation angle θ _a with the motor center point as the origin, and multiplies the calculated integrated angle by a conversion coefficient based on the reduction ratio of the speed reduction mechanism 23. Thus, the steering angle θ _s of the steering wheel 11 is calculated.

The reaction force control unit 27 executes reaction force control to generate a steering reaction force according to the steering torque _Th through drive control of the reaction force motor 22. The reaction force control unit 27 calculates a target steering reaction force based on the steering torque _Th detected through the torque sensor 25, and adjusts the target steering angle of the steering wheel ₁₁ based on the calculated target steering reaction force and steering torque Th. Calculate. The reaction force control unit 27 determines the difference between the steering angle θ _s calculated based on the rotation angle θ _a of the reaction force motor 22 and the target steering angle, and controls the power supply to the reaction force motor 22 so as to eliminate the difference. . The reaction force control unit 27 vector-controls the reaction force motor 22 using the rotation angle θ _a of the reaction force motor 22 detected through the rotation angle sensor 24 .

The steering unit 30 includes a steering shaft 31 , a steering motor 32 , a speed reduction mechanism 33 , a pinion shaft 34 , a rotation angle sensor 35 , and a steering control section 36 .
The steering shaft 31 extends along the vehicle width direction (left-right direction in FIG. 1). Left and right steered wheels 12 are connected to both ends of the steered shaft 31 via tie rods 13, 13, respectively.

The steering motor 32 is a source of steering force. As the steering motor 32, for example, a three-phase brushless motor is employed. The steering motor 32 is connected to a pinion shaft 34 via a speed reduction mechanism 33. The pinion teeth 34a of the pinion shaft 34 are engaged with the rack teeth 31a of the steered shaft 31. The torque generated by the steering motor 32 is applied to the steering shaft 31 via the pinion shaft 34 as a steering force. In accordance with the rotation of the steering motor 32, the steering shaft 31 moves along the vehicle width direction (left-right direction in FIG. 1). By moving the steered shaft 31, the steered angle θ _w of the steered wheels 12 is changed.

The rotation angle sensor 35 is provided on the steering motor 32. The rotation angle sensor 35 detects the rotation angle θ _b of the steering motor 32 .
The steering control section 36, like the reaction force control section 27, has a processing circuit including any one of the above three configurations C1, C2, and C3.

The steering control unit 36 performs steering control to steer the steered wheels 12 according to the steering state through drive control of the steered motor 32. The steering control unit 36 calculates a pinion angle θ _p that is a rotation angle of the pinion shaft 34 based on the rotation angle θ _b of the steering motor 32 detected through the rotation angle sensor 35 . Further, the steering control unit 36 uses the target steering angle calculated by the reaction force control unit 27 to calculate a target pinion angle that is a target rotation angle of the pinion shaft 34 . However, the target rotation angle of the pinion shaft 34 is calculated based on the viewpoint of realizing a predetermined steering angle ratio. The steering control unit 36 determines the difference between the target pinion angle of the pinion shaft 34 and the actual pinion angle θ _p , and controls power supply to the steering motor 32 so as to eliminate the difference. The steering control unit 36 performs vector control on the steering motor 32 using the rotation angle θ _b of the steering motor 32 detected through the rotation angle sensor 35 .

Note that the reaction force control unit 27 and the steering control unit 36 constitute a steering control device that controls the steering device 10.
<Configuration of reaction force control section 27>
Next, the configuration of the reaction force control section 27 will be explained in detail.

As shown in FIG. 2, the reaction force control section 27 includes a steering angle calculation section 51, a steering reaction force command value calculation section 52, and an energization control section 53.
The steering angle calculating section 51 calculates the steering angle θ _s of the steering wheel 11 based on the rotation angle _{θ a} of the reaction force motor 22 detected through the rotation angle sensor 24 .

The steering reaction force command value calculating section 52 calculates a steering reaction force command value T ^* based on the steering torque T _h and the vehicle speed V. The steering reaction force command value calculating section 52 calculates a steering reaction force command value T ^* having a larger absolute value as the absolute value of the steering torque T _h is larger and as the vehicle speed V is lower. The steering reaction force command value T ^* corresponds to a second command value for the reaction force motor 22.

The energization control unit 53 supplies the reaction force motor 22 with electric power according to the steering reaction force command value T ^* . Specifically, the energization control unit 53 calculates a current command value for the reaction force motor 22 based on the steering reaction force command value T ^* . Further, the energization control unit 53 detects, through a current sensor 54 provided in the power supply path to the reaction force motor 22, the value of the actual current _Ia generated in the power supply path. The value of this current _Ia is the actual value of the current supplied to the reaction force motor 22. Then, the energization control unit 53 determines the deviation between the current command value and the actual value of the current _Ia , and controls the power supply to the reaction force motor 22 so as to eliminate the deviation. Thereby, the reaction force motor 22 generates torque according to the steering reaction force command value T ^* . It is possible to provide the driver with an appropriate feeling of response depending on the road reaction force.

<Configuration of steering control section 36>
Next, the configuration of the steering control section 36 will be explained in detail.
As shown in FIG. 2, the steering control section 36 includes a pinion angle calculation section 61, a target pinion angle calculation section 62, a pinion angle feedback control section 63, and an energization control section 64.

The pinion angle calculating section 61 calculates a pinion angle θ _p which is the actual rotation angle of the pinion shaft 34 based on the rotation angle θ _b of the steered motor 32 detected through the rotation angle sensor 35 . The steering motor 32 and pinion shaft 34 are interlocked via a speed reduction mechanism 33. Therefore, there is a correlation between the rotation angle θ _b of the steering motor 32 and the pinion angle θ _p . Using this correlation, the pinion angle θ _p can be determined from the rotation angle θ _b of the steering motor 32. Further, the pinion shaft 34 is meshed with the steered shaft 31. Therefore, there is also a correlation between the pinion angle θ _p and the amount of movement of the steered shaft 31. That is, the pinion angle θ _p is a value that reflects the steered angle θ _w of the steered wheels 12 .

The target pinion angle calculation unit 62 calculates a target pinion angle θ _p ^* based on the steering angle θ _s calculated by the steering angle calculation unit 51 . In this embodiment, the target pinion angle calculation unit 62 sets the target pinion angle θ _p ^* to the same value as the steering angle θ _s . That is, the steering angle ratio, which is the ratio between the steering angle θ _s and the turning angle θ _w, is “1:1”.

Incidentally, the target pinion angle calculation unit 62 may set the target pinion angle θ _p ^* to a value different from the steering angle θ _s . That is, the target pinion angle calculation unit 62 sets a steering angle ratio, which is the ratio of the steering angle θ _w to the steering angle θ _s , according to the running state of the vehicle, such as the vehicle speed V, and the set steering angle ratio The target pinion angle θ _p ^* is calculated according to. The target pinion angle calculation unit 62 is configured such that the slower the vehicle speed V, the larger the turning angle θ _w with respect to the steering angle θ _s , and the faster the vehicle speed V, the smaller the turning angle θ _w with respect to the steering angle θ _s . The target pinion angle θ _p ^* is calculated as follows. The target pinion angle calculation unit 62 calculates a correction angle for the steering angle θ _s in order to realize a steering angle ratio set according to the driving state of the vehicle, and applies the calculated correction angle to the steering angle θ _s. By adding them, a target pinion angle θ _p ^* corresponding to the steering angle ratio is calculated.

The pinion angle feedback control unit 63 takes in the target pinion angle θ _p ^* calculated by the target pinion angle calculation unit 62 and the actual pinion angle θ _p calculated by the pinion angle calculation unit 61 . The pinion angle feedback control unit 63 sets a torque command value T _{p *} for the torque generated by the steering motor 32 through feedback control of the pinion angle θ _p so that the actual pinion angle θ _p follows the target pinion angle θ p ^{* .} calculate. The torque command value T _p ^* corresponds to a first command value for the steering motor 32 .

The energization control unit 64 supplies the steering motor 32 with electric power according to the torque command value T _p ^* . Specifically, the energization control unit 64 calculates a current command value for the steering motor 32 based on the torque command value T _p ^* . Further, the energization control unit 64 detects, through a current sensor 65 provided in the power supply path to the steering motor 32, the value of the actual current _Ib generated in the power supply path. The value of this current _Ib is the actual value of the current supplied to the steering motor 32. Then, the energization control unit 64 determines the deviation between the current command value and the actual value of the current _Ib , and controls the power supply to the steering motor 32 so as to eliminate the deviation. As a result, the steering motor 32 rotates by an angle corresponding to the torque command value T _p ^* .

In the steer-by-wire steering system 10, when the steering wheel 11 is operated by the driver, the steering force generated by the steering motor 32 and the axial force acting on the steering shaft 31 are balanced while maintaining force balance. The steered wheels 12 are steered. However, for example, when the friction of the road surface is large, an excessive axial force is generated on the steering shaft 31, so that the steering force, which is the output of the steering motor, may be insufficient. In this case, it may be difficult to smoothly steer the steered wheels 12.

Therefore, in this embodiment, in order to more smoothly steer the steered wheels 12 even when an excessive axial force is generated on the steered shaft 31, the following configuration is adopted as the steering control section 36. There is.

<Supplementary explanation of the steering control unit 36>
As shown in FIG. 3A, the steering control section 36 includes a pinion angle calculation section 61 (not shown), a target pinion angle calculation section 62 (not shown), a pinion angle feedback control section 63, and an energization control section. In addition to 64, it has a determination section 71 and an arbitration processing section 72.

The determination unit 71 sets the value of the classification F depending on the turning state of the steerable wheels 12 and the running state of the vehicle. Classification F is information indicating whether the state of the vehicle is such that an excessive axial force is likely to be generated on the steering shaft 31, that is, whether the state is such that the steering force is likely to be insufficient. The determination unit 71 executes a first determination process, a second determination process, a third determination process, and a fourth determination process.

<DP1. First determination process>
As a first determination process, the determination unit 71 determines whether both of the following two relational expressions (A1) and (A2) hold true.

A1. "θ _w >0" and "ω _w > ω _wth "
A2.0≦V≦V _th
However, “θ _w ” is the steering angle of the steered wheels 12. The steering angle θ _w is calculated based on the pinion angle θ _p calculated by the pinion angle calculation unit 61, for example. The sign of the steering angle θ _w is, for example, positive when the steered wheels 12 are steered to the left with respect to the steered neutral position, and negative when the steered wheels 12 are steered to the right. . The steered neutral position is a position of the steered wheels 12 that corresponds to the straight-ahead state of the vehicle. “ω _w ” is the steering angular velocity. The steering angular velocity ω _w is obtained, for example, by differentiating the steering angle θ _w . “ω _wth ” is a steering angular velocity threshold. The steering angular velocity threshold ω _wth is set to a value near “0”, for example. "V" is the vehicle speed detected through the vehicle speed sensor. “V _th ” is the vehicle speed threshold. The vehicle speed threshold V _th is set based on an extremely low speed (for example, 5 km/h). This is because a situation where the vehicle is stopped or a situation where the vehicle is running at an extremely low speed can be said to be a situation where a larger axial force is likely to be generated due to the operation of the steering wheel 11.

The determination unit 71 determines that the steering wheel 11 is being steered to the left when the relational expression (A1) is satisfied, with reference to the neutral steering position. The cutting steering is an operation of the steering wheel 11 that attempts to steer the steered wheels 12 in a direction in which the absolute value of the steered angle θ _w increases with reference to the neutral steering position. The neutral steering position is a position of the steering wheel 11 that corresponds to a straight-ahead state of the vehicle. Further, when the relational expression (A2) is satisfied, the determination unit 71 determines that the vehicle is in a stopped state or a state in which the vehicle is running at an extremely low speed. The determination unit 71 sets the value of the division F to the second boost-up state S _b2 when both of the two relational expressions (A1) and (A2) are satisfied.

<DP2. Second determination process>
As a second determination process, the determination unit 71 determines whether both of the following two relational expressions (A3) and (A4) hold true.

A3. “θ _w <0” and “ω _w <-ω _wth ”
A4.0≦V≦V _th
The determination unit 71 determines that the steering wheel 11 is being steered to the right when relational expression (A3) is satisfied, with the steering neutral position as a reference. Further, when the relational expression (A4) is satisfied, the determination unit 71 determines that the vehicle is in a stopped state or a state in which the vehicle is running at an extremely low speed. The determination unit 71 sets the value of the division F to the second boost-up state S _b2 when both of the two relational expressions (A3) and (A4) are satisfied.

<DP3. Third determination process>
As a third determination process, the determination unit 71 determines whether both of the following two relational expressions (A5) and (A6) hold true.

A5. "θ _w >0" and "ω _w < ω _wth "
A6.0≦V≦V _th
The determination unit 71 determines that the steering wheel 11 is being steered back from left to right when relational expression (A5) is satisfied. The return steering is an operation of the steering wheel 11 that attempts to turn the steered wheels 12 in a direction that returns them to the neutral steering position. Further, when the relational expression (A6) is satisfied, the determination unit 71 determines that the vehicle is in a stopped state or a state in which the vehicle is running at an extremely low speed. The determination unit 71 sets the value of the division F to the first boost-up state S _b1 when both of the two relational expressions (A5) and (A6) are satisfied.

<DP4. Fourth determination process>
As a fourth determination process, the determination unit 71 determines whether both of the following two relational expressions (A7) and (A8) hold true.

A7. “θ _w <0” and “ω _w >−ω _wth ”
A8.0≦V≦V _th
The determining unit 71 determines that the steering wheel 11 is being steered back from the right to the left when the relational expression (A7) is satisfied. Further, when the relational expression (A8) is satisfied, the determination unit 71 determines that the vehicle is in a stopped state or a state in which the vehicle is running at an extremely low speed. The determination unit 71 sets the value of the division F to the first boost-up state S _b1 when both of the two relational expressions (A7) and (A8) are satisfied.

The determination unit 71 determines that none of the relational expressions (A1), (A2), the relational expressions (A3), (A4), the relational expressions (A5), (A6), and the relational expressions (A7), (A8) hold true. At this time, the value of section F is set to the non-boost-up state S _b0 .

The arbitration processing unit 72 executes boost-up processing according to the value of the classification F set by the determination unit 71. The boost-up process is a process for increasing the torque command value T _p ^* calculated by the pinion angle feedback control unit 63, and corresponds to the first process. The arbitration processing unit 72 executes, for example, the following process as the boost-up process.

That is, the arbitration processing unit 72 multiplies the torque command value T _p ^* calculated by the pinion angle feedback control unit 63 by the gain G _en as expressed by the following equation (1) to obtain the final result. Calculate torque command value T _p ^* .

T _p ^* (final) = T _p ^*・G _en … (1)
However, the value of the gain _Gen is set based on the viewpoint of maintaining a balance between the axial force generated on the steered shaft 31 and the steering force generated by the steered motor 32. The value of the gain G _en is set, for example, through simulation based on driving conditions.

The value of gain _Gen differs depending on the value of division F. The magnitude relationship of the gain G _en according to the value of the division F is as shown in the following equation (2).
_Gen0 < _Gen1 < _Gen2 ...(2)
However, “G _en0 ” is the value of the gain G _en used when the value of the division F is the non-boost-up state S _b0 , and is set to, for example, “1.0”. “G _en1 ” is the value of the gain G _en used when the value of the division F is the first boost-up state S _b1 , and is set to, for example, “1.1”. “G _en2 ” is the value of the gain G _en used when the value of the division F is the second boost-up state S _b2 , and is set to, for example, “1.2”.

The reason why the gain G _en2 for the second boost-up state S _b2 is set to a larger value than the value of the gain G _en1 for the first boost-up state S _b1 is as follows, for example.

That is, the steering force required when the cut-in steering is performed is larger than the steering force required when the cut-back steering is performed. This is because, for example, when reverse steering is performed, self-aligning torque is applied. For this reason, it can be said that when turning steering is performed, the steering force is more likely to be insufficient than when turning back steering is performed. Therefore, the gain G _en2 for the second boost-up state S _b2 is set to a larger value than the value of the gain G _en1 for the first boost-up state S _b1 .

When the value of the division F is the non-boost-up state S _b0 , the boost-up process is not executed. When the value of division F is the non-boost-up state S _b0 , the final torque command value T _p ^* becomes the same value as the torque command value T _p ^* calculated by the pinion angle feedback control section 63. That is, the torque command value T _p ^* calculated by the pinion angle feedback control section 63 is used as the final torque command value T _p ^* . The energization control unit 64 supplies electric power to the steering motor 32 according to the final torque command value T _p ^* .

When the value of division F is the first boost-up state S _b1 and the second boost-up state S _b2 , the boost-up process is executed. When the value of division F is the first boost-up state S _b1 and the second boost-up state S _b2 , the final torque command value T _p ^* is the torque command value T _p calculated by the pinion angle feedback control unit 63 The value will be larger than ^* . Therefore, the amount of current supplied to the steering motor 32 becomes larger than the normal amount of current according to the torque command value T _p ^* calculated by the pinion angle feedback control section 63. Therefore, as the amount of current supplied to the steering motor 32 increases, the steering force generated by the steering motor 32 also increases.

Incidentally, the arbitration processing unit 72 calculates the final value by adding the additional value T _se to the torque command value T _p ^* calculated by the pinion angle feedback control unit 63, as expressed by the following equation (3). The torque command value T _p ^* may be calculated.

T _p ^* (final) = T _p ^* + T _se ... (3)
However, the additional value _Tse is set based on the viewpoint of maintaining a balance between the axial force generated on the steered shaft 31 and the steering force generated by the steered motor 32. The additional value T _se is set, for example, through simulation based on driving conditions.

The value of the additional value T _se differs depending on the value of the classification F. The magnitude relationship of the additional value T _se according to the value of the division F is as shown in the following equation (4).
T _se0 <T _se1 <T _se2 (4)
However, “T _se0 ” is the value of the addition value T _se used when the value of the division F is the non-boost-up state S _b0 , and is set to, for example, “0”. "T _se1 " is the value of the addition value T _se used when the value of the division F is the first boost-up state S _b1 , and is set to an absolute value larger than "0". “T _se2 ” is the value of the addition value T _se used when the value of the division F is the second boost-up state S _b2 , and is set to an absolute value larger than “0”.

Even in this case, when the steering force is likely to be insufficient, that is, when the value of division F is the first boost-up state S _b1 and the second boost-up state S _b2 , the boost-up process is executed. . Therefore, the final torque command value T _p ^* becomes a value larger than the torque command value T _p ^* calculated by the pinion angle feedback control section 63. As a result, the steering force generated by the steering motor 32 can be increased to a force greater than the steering force corresponding to the normal torque command value T _p ^* calculated by the pinion angle feedback control unit 63.

<Change in the value of category F over time>
Next, an example of a change over time in the value of division F depending on the steering state of the steering wheel 11 and the driving state of the vehicle will be described.

As shown in the graph of FIG. 4A, for example, when the steering wheel 11 is steered to the left with respect to the neutral steering position, the turning angle θ _w takes a positive value. The value of the steering angle θ _w corresponding to the neutral steering position is, for example, “0”. As the amount of operation of the steering wheel 11 increases, the steered angle θ _w increases in the positive direction, and eventually reaches the maximum positive steered angle θ _we which is the limit position of the physical movable range of the steered wheels 12 ( time t1). At this time, as shown in FIG. 4(b), the turning angular velocity ω _w is a positive value, for example, a value greater in the positive direction than the positive turning angular velocity threshold ω _wth . As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", both of the previous two relational expressions (A1) and (A2) are satisfied. Therefore, as shown in FIG. 4(d), the value of section F is set to the second boost-up state S _b2 .

As shown in the graphs of FIGS. 4(a) and 4(b), the value of the turning angular velocity ω _w is "0" during the period when the turning angle θ _w is maintained at the positive maximum turning angle θ _we . . As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", the above relational expressions (A1), (A2), relational expressions (A3), (A4), Neither relational expressions (A5) and (A6), nor relational expressions (A7) and (A8) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 .

As shown in the graph of FIG. 4(a), when the steering wheel 11 is steered back to the right while the steering angle θ _w is maintained at the positive maximum steering angle θ _we (time t2), As the steering wheel 11 is steered, the turning angle θ _w gradually decreases toward "0", which is a value corresponding to the neutral steering position, and eventually reaches "0" (time t3). At this time, as shown in FIG. 4(b), the turning angular velocity ω _w is a negative value, and is larger in the negative direction than, for example, the negative turning angular velocity threshold ω _wth . That is, the turning angular velocity ω _w has a value smaller than the positive turning angular velocity threshold ω _wth . As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", both of the previous two relational expressions (A5) and (A6) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the first boost-up state S _b1 .

As shown in the graph of FIG. 4(a), after the steering wheel 11 reaches the neutral steering position, when the steering wheel 11 is subsequently turned to the right and steered, the turning angle θ _w becomes a negative value. As the amount of operation of the steering wheel 11 increases, the steered angle θ _w increases in the negative direction, and eventually reaches the negative maximum steered angle −θ _we which is the limit position of the physical movable range of the steered wheels 12. (Time t4). At this time, as shown in FIG. 4(b), the turning angular velocity ω _w is a negative value, and is larger in the negative direction than the negative turning angular velocity threshold ω _wth . As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", both of the previous two relational expressions (A3) and (A4) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the second boost-up state S _b2 .

As shown in the graphs of FIGS. 4(a) and 4(b), during the period when the turning angle θ _w is maintained at the negative maximum turning angle −θ _we , the value of the turning angular velocity ω _w is “0”. be. As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", the above relational expressions (A1), (A2), relational expressions (A3), (A4), Neither relational expressions (A5) and (A6), nor relational expressions (A7) and (A8) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 .

As shown in the graph of FIG. 4(a), when the steering wheel 11 is steered back to the left while the steering angle θ _w is maintained at the negative maximum steering angle −θ _we (time t5) As the steering wheel 11 is steered, the turning angle θ _w gradually increases toward "0", which is a value corresponding to the neutral steering position, and eventually reaches "0" (time t6). During this period, as shown in FIG. 4(b), the turning angular velocity ω _w is a positive value, for example, a value greater in the positive direction than the negative turning angular velocity threshold −ω _wth . As shown in the graph of FIG. 4(c), in this state, when the value of the vehicle speed V is "0", both of the previous two relational expressions (A7) and (A8) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the first boost-up state S _b1 . Incidentally, the vehicle speed V starts to increase at time t6.

As shown in the graph of FIG. 4(a), when the steering wheel 11 is subsequently turned to the left after reaching the neutral steering position, the turning angle θ _w becomes a positive value. As the amount of operation of the steering wheel 11 increases, the steered angle θ _w increases in the positive direction, and eventually reaches the maximum positive steered angle θ _we which is the limit position of the physical movable range of the steered wheels 12 ( time t7). Within this period, as shown in FIG. 4(b), the turning angular velocity ω _w has a positive value, and is larger in the positive direction than the positive turning angular velocity threshold ω _wth . . As shown in the graph of FIG. 4(c), for example, during the period (time t8) from when the value of the vehicle speed V starts to increase from "0" until it reaches the vehicle speed threshold value V _th , the above two relational expressions (A1 ) and (A2) both hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the second boost-up state S _b2 . Furthermore, after the value of the vehicle speed V exceeds the vehicle speed threshold value V _th , the above relational expressions (A1), (A2), relational expressions (A3), (A4), relational expressions (A5), (A6), And neither of the relational expressions (A7) and (A8) holds true. Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 .

As shown in the graphs of FIGS. 4(a) and 4(b), the value of the turning angular velocity ω _w is "0" during the period when the turning angle θ _w is maintained at the positive maximum turning angle θ _we . . Therefore, none of the above relational expressions (A1), (A2), relational expressions (A3), (A4), relational expressions (A5), (A6), and relational expressions (A7), (A8) hold. . Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 . Incidentally, as shown in the graph of FIG. 4(c), during the period in which the turning angle θ _w is maintained at the positive maximum turning angle θ _we , the value of the vehicle speed V is, for example, equal to the vehicle speed threshold value V _th The vehicle speed changes from a value exceeding _Vth to a value below the vehicle speed threshold Vth.

As shown in the graph of FIG. 4(a), when the steering wheel 11 is turned back to the right while the steering angle θ _w is maintained at the positive maximum steering angle θ _we (time t9), As the steering wheel 11 is steered, the turning angle θ _w gradually decreases toward "0", which is a value corresponding to the neutral steering position, and eventually reaches "0" (time t10). Within this period, as shown in FIG. 4(b), the turning angular velocity ω _w has a negative value, and is larger in the negative direction than the negative turning angular velocity threshold ω _wth . . That is, the turning angular velocity ω _w has a value smaller than the positive turning angular velocity threshold ω _wth . Therefore, both of the previous two relational expressions (A5) and (A6) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the first boost-up state S _b1 . Incidentally, as shown in the graph of FIG. 4(c), in the middle of the period in which the steering angle θ _w decreases from the positive maximum steering angle θ _we to "0", which is the value corresponding to the neutral steering position. , the value of the vehicle speed V increases from a value less than the vehicle speed threshold V _th toward the vehicle speed threshold V _th . The value of the vehicle speed V reaches the vehicle speed threshold value V _th at the timing when the steering angle θ _w reaches "0".

As shown in the graph of FIG. 4(a), after the steering angle θ _w decreases from the positive maximum steering angle θ _we and reaches "0", when the steering wheel 11 is turned to the right and steered ( At time t10), as the steering wheel 11 is steered, the turning angle θ _w increases in the negative direction, and eventually reaches the negative maximum turning angle −θ _we , which is the limit position of the physical movable range of the steering wheel 12. (time t11). At this time, as shown in FIG. 4(b), the turning angular velocity ω _w is a negative value, and is larger in the negative direction than, for example, the negative turning angular velocity threshold ω _wth . However, as shown in the graph of FIG. 4(c), for example, the value of the vehicle speed V exceeds the vehicle speed threshold V _th . Therefore, although the above relational expression (A3) holds true, the relational expression (A4) does not hold. Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 .

As shown in the graphs of FIGS. 4(a) and 4(b), during the period when the turning angle θ _w is maintained at the negative maximum turning angle −θ _we , the value of the turning angular velocity ω _w is “0”. be. Further, as shown in the graph of FIG. 4(c), the value of the vehicle speed V is maintained in a state exceeding, for example, the vehicle speed threshold value V _th . Therefore, none of the above relational expressions (A1), (A2), relational expressions (A3), (A4), relational expressions (A5), (A6), and relational expressions (A7), (A8) hold. . Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 .

As shown in the graph of FIG. 4(a), when the steering wheel 11 is steered back to the left while the steering angle θ _w is maintained at the negative maximum steering angle −θ _we (time t12) As the steering wheel 11 is steered, the turning angle θ _w gradually increases toward "0", which is a value corresponding to the neutral steering position, and eventually reaches "0" (time t13). During this period, as shown in FIG. 4(b), the turning angular velocity ω _w is a positive value, for example, a value greater in the positive direction than the negative turning angular velocity threshold −ω _wth . As shown in the graph of FIG. 4(c), during the period until the steering angle θ _w changes from the negative maximum steering angle -θ _we to "0", the vehicle speed V is, for example, the vehicle speed threshold value V It gradually decreases from a value exceeding _th toward "0" and reaches "0" at the timing when the steering angle θ _w reaches "0". Therefore, when the vehicle speed V exceeds the vehicle speed threshold value V _th , the above relational expression (A7) holds, but the relational expression (A8) does not hold. Therefore, as shown in FIG. 4(d), the value of section F is set to the non-boost-up state S _b0 . After the vehicle speed V decreases to a value equal to or less than the vehicle speed threshold V _th (time t14), both of the above relational expressions (A7) and (A8) hold true. Therefore, as shown in FIG. 4(d), the value of section F is set to the first boost-up state S _b1 .

As described above, when the steering wheel 11 is steered and the vehicle speed V is "0" or a value equal to or lower than the vehicle speed threshold V _th , the value of the classification F is the second boost-up state. Set to S _b2 . Further, when the steering wheel 11 is steered back and the vehicle speed V is "0" or a value equal to or lower than the vehicle speed threshold value V _th , the value of the classification F is the first boost-up state S _b1 is set to In addition, when the steering wheel 11 is kept steered or when the value of the vehicle speed V exceeds the vehicle speed threshold value V _th , the value of the division F is set to the non-boost-up state S _b0 .

<Notification processing for the driver>
As the output of the steering motor 32 continues to increase through execution of the boost-up process, there is a possibility that the steering motor 32 or the inverter that supplies power to the steering motor 32 may reach an overheating state. Therefore, in the present embodiment, during the period when the boost-up process is executed, a notification process is executed to notify the driver that the boost-up process is being executed. The notification process corresponds to the second process. Specifically, it is as follows.

As shown in FIG. 3A, the reaction force control section 27 takes in the value of the division F set by the determination section 71 of the steering control section 36. When the steering control unit 36 is in a situation where boost-up processing is to be executed, the reaction force control unit 27 executes a notification process that is a process for notifying the driver of the vehicle of this fact. The reaction force control unit 27 determines that when the value of the division F is the first boost-up state S _b1 or the second boost-up state S _b2 , the steering control unit 36 is in a situation where the boost-up process is executed. recognize.

The reaction force control unit 27 executes a process for increasing the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, for example, as the notification process. The reaction force control unit 27 increases the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, for example, by executing the same process as the arbitration processing unit 72 of the steering control unit 36.

That is, the reaction force control unit 27 multiplies the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 by the gain G _rf , as expressed by the following equation (5). Accordingly, the final steering reaction force command value T ^* is calculated.

T ^* (final)=T ^*・G _rf …(5)
However, the value of the gain G _rf is determined from the viewpoint of notifying the driver that the boost-up process is to be executed through the feeling of response through the steering wheel 11, and from the viewpoint of suppressing the steering of the steering wheel 11 by the driver. is set to a value greater than "1" based on . Therefore, the final steering reaction force command value T ^* becomes a value larger than the steering reaction force command value T ^* calculated by the steering reaction force command value calculating section 52.

Incidentally, the reaction force control unit 27 adds the additional value T _rf to the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, as expressed by the following equation (6). , the final steering reaction force command value T ^* may be calculated.

T ^* (final)=T ^* +T _rf …(6)
However, the additional value _Tse is set based on the viewpoint of visually informing the driver that the boost-up process is to be executed through the steering wheel 11 through the steering wheel 11. The final steering reaction force command value T ^* is a value larger than the steering reaction force command value T ^* calculated by the steering reaction force command value calculating section 52.

Therefore, when the boost-up process is executed, the final steering reaction force command value T ^* becomes a value larger than the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52. . Therefore, the steering reaction force generated by the reaction force motor 22 increases to a force larger than the steering reaction force corresponding to the normal steering reaction force command value T ^* calculated by the steering reaction force command value calculating section 52. By feeling a response through the steering wheel 11, the driver of the vehicle can intuitively recognize that the boost-up process is to be executed.

<Effects of the first embodiment>
The first embodiment has the following effects.
(1-1) When the steering force is likely to be insufficient, the torque command value T _p ^* is increased to a value larger than the normal torque command value T _p ^* calculated by the pinion angle feedback control section 63. Ru. Thereby, the steering motor 32 generates a steering force larger than the steering force according to the normal torque command value T _p ^* calculated by the pinion angle feedback control unit 63. In this way, by increasing the steering force generated by the steering motor 32 in advance in preparation for a situation where the steering force is insufficient, even if a large axial force is actually generated on the steering shaft, The steered wheels 12 can be smoothly steered without insufficient steering force.

(1-2) The reaction force control unit 27 recognizes the execution status of the boost-up process based on the value of the division F set by the steering control unit 36. The reaction force control unit 27 executes a process for increasing the value of the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 during the period when the boost up process is executed. Therefore, the reaction force motor 22 generates a steering reaction force that is larger than the normal steering reaction force according to the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52. By feeling a response through the steering wheel 11, the driver of the vehicle can recognize that the boost-up process is being executed, that is, that the steering force has increased compared to normal. Further, since a steering reaction force larger than a normal steering reaction force is applied to the steering wheel 11, active steering of the steering wheel 11 by the driver is suppressed. Therefore, overheating of the steering motor 32 or the inverter that supplies power to the steering motor 32 can be suppressed.

(1-3) When the steering wheel 11 is steered while the vehicle is running at an extremely low speed range, excessive axial force is likely to be generated on the steering shaft 31. Therefore, by configuring the steering control unit 36 to determine that when the vehicle speed is in an extremely low speed range and the steering wheel 11 is being steered, the steering force is likely to be insufficient, The rudder control unit 36 can perform boost-up processing at appropriate timing.

(1-4) The reaction force control unit 27 multiplies the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 by a gain _Gen during the period when the boost up process is executed. Alternatively, the value of the steering reaction force command value ^T* _can be easily increased by adding the additional value Tse.

(1-5) The steering force required when the cut-in steering is performed is larger than the steering force required when the cut-back steering is performed. That is, it can be said that when turning steering is performed, the steering force is more likely to be insufficient than when turning back steering is performed. For this reason, when executing the boost-up process, the steering control unit 36 controls the degree of increase in the torque command value T _p * when the steering wheel 11 is turned back to the degree of increase in the torque command value T p ^* when the steering wheel 11 is turned back. The degree of increase in torque command value T _p ^* should be greater than the degree of increase. Therefore, the steered wheels 12 can be smoothly steered without insufficient steering force, whether the steering wheel 11 is steered by the steering wheel 11 or the steering wheel 11 is steered back.

(1-6) As boost-up processing, the steering control unit 36 multiplies the original torque command value T _p ^* according to the steering state of the steering wheel 11 by a gain G _rf , or adds an additional value T _rf . By adding, the value of the torque command value T _p ^* can be easily increased.

<Second embodiment>
Next, a second embodiment embodying a steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in FIGS. 1 and 2 above. This embodiment differs from the first embodiment in that the energization control section 64 has the same processing function as the arbitration processing section 72 described above. In this embodiment, a configuration in which the above-mentioned arbitration processing section 72 is omitted is adopted as the steering control section 36. Therefore, the same members and configurations as in the first embodiment are given the same reference numerals as in the first embodiment, and detailed description thereof will be omitted.

As shown in FIG. 3(b), the energization control section 64 takes in the value of category F set by the determination section 71. Further, the energization control section 64 takes in the torque command value T _p ^* calculated by the pinion angle feedback control section 63 as the final torque command value T _p ^* .

The energization control unit 64 applies a current command value I ^* to the steering motor 32 calculated based on the torque command value T _p ^* calculated by the pinion angle feedback control unit 63, as expressed by the following equation (7). The final current command value I ^* is calculated by multiplying by the gain G _en .

I ^* (final) = I ^*・G _en … (7)
However, the value of gain _Gen differs depending on the value of division F. The magnitude relationship of the gain G _en according to the value of the division F is as shown in equation (2) in the first embodiment.

In this way, when the steering force is likely to be insufficient, the final current command value I ^* can be converted into a current command according to the normal torque command value T _p ^* calculated by the pinion angle feedback control section 63. It can be greater than the value I ^* . As a result, the steering force generated by the steering motor 32 can be increased to a force greater than the steering force corresponding to the normal torque command value T _p ^* calculated by the pinion angle feedback control unit 63.

Incidentally, when the energization control section 64 is provided with the same processing function as the arbitration processing section 72, the energization control section 64 adjusts the torque calculated by the pinion angle feedback control section 63 as expressed by the following equation (8). The final current command value I ^* may be calculated by adding the additional value _Ise to the current command value I ^* for the steering motor 32 calculated based on the command value _Tp ^* .

I ^* (final) = I ^* + I _se ... (8)
However, the additional value _Ise is set based on the viewpoint of maintaining a balance between the axial force generated on the steered shaft 31 and the steering force generated by the steered motor 32. The additional value _Ise is set, for example, through a simulation based on the driving situation.

The value of the additional value I _se differs depending on the value of the classification F. The magnitude relationship of the additional value I _se according to the value of the division F is as shown in the following equation (4).
I _se0 <I _se1 <I _se2 (9)
However, “I _se0 ” is the value of the addition value I _se that is used when the value of the division F is the non-boost-up state S _b0 , and is set to, for example, “0”. "I _se1 " is the value of the addition value T _se used when the value of the division F is the first boost-up state S _b1 , and is set to an absolute value larger than "0". "I _se2 " is the value of the addition value T _se used when the value of the division F is the second boost-up state S _b2 , and is set to an absolute value larger than "0".

Even in this case, when the steering force is likely to be insufficient, the final current command value I ^* is changed to the current command value I according to the torque command value T _p ^* calculated by the pinion angle feedback control section 63. It can be set to a value larger than ^* . As a result, the steering force generated by the steering motor 32 can be increased to a force greater than the steering force corresponding to the normal torque command value T _p ^* calculated by the pinion angle feedback control unit 63.

The reaction force control unit 27 executes a process for increasing the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, for example, as the notification process. The reaction force control section 27 increases the steering reaction force command value T ^* calculated by the steering reaction force command value calculation section 52 in the same manner as in the first embodiment. That is, the reaction force control unit 27 multiplies the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 by the gain G _rf , as expressed by the above equation (5). By doing so, the final steering reaction force command value T ^* is calculated.

Incidentally, similarly to the first embodiment, the reaction force control section 27 performs the notification process by calculating the steering reaction force calculated by the steering reaction force command value calculation section 52, as expressed by the above equation (6). The final steering reaction force command value T ^* may be calculated by adding the additional value T _rf to the force command value T ^* .

<Effects of the second embodiment>
The second embodiment has the following effects.
(2-1) When the steering force is likely to be insufficient, the current command value I ^* is larger than the normal current command value corresponding to the torque command value T _p ^* calculated by the pinion angle feedback control unit 63 value is increased. Thereby, the steering motor 32 generates a steering force larger than the steering force according to the normal torque command value T _p ^* calculated by the pinion angle feedback control unit 63. In this way, by increasing the steering force generated by the steering motor 32 in advance in preparation for a situation where the steering force is insufficient, even if a large axial force is actually generated, the steering force will be insufficient. The steered wheels 12 can be smoothly steered without having to do so.

(2-2) Furthermore, effects similar to those in columns (1-2) to (1-5) of the first embodiment can be obtained.
<Third embodiment>
Next, a third embodiment that embodies a steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in FIGS. 1 and 2 above. Therefore, the same members and configurations as in the first embodiment are given the same reference numerals, and detailed explanations thereof will be omitted.

In the steering device 10, a situation is assumed in which, for example, it is difficult to steer the steered wheels 12 toward the additional steering side or the reverse steering side, such as when the steered wheels collide with a curb during stationary steering. At this time, the steering control unit 36 attempts to cause the steering _angle of the steered wheels 12 to follow the steering angle θ s of the steering wheel 11. Therefore, there is a possibility that an excessive current is supplied to the steering motor 32. Therefore, in this embodiment, the steering control section 36 has the following configuration.

As shown in FIG. 5A, the steering control section 36 includes a pinion angle calculation section 61 (not shown), a target pinion angle calculation section 62 (not shown), a pinion angle feedback control section 63, and an energization control section. 64, a limit value setting section 73 in addition to the determination section 71 and the arbitration processing section 72.

The limit value setting section 73 sets a limit value T _L for limiting the range of change of the torque command value T _p ^* calculated by the pinion angle feedback control section 63 . The limit value T _L is also a limit value of an allowable range in which a change in the torque command value T _p ^* is allowed. The limit value T _L is such that even if an excessive torque command value T _p ^* is calculated for some reason, an excessive current is supplied to the steering motor 32 based on this excessive torque command value T _p ^* ; Furthermore, it is set based on the viewpoint of suppressing the steering motor 32 from generating excessive torque. In this embodiment, the limit value T _L is set as a fixed value stored in the storage device of the steering control section 36 . The limit value T _L is set, for example, to a value of about 80% of the maximum value (100%) of the torque command value T _p ^* corresponding to the maximum torque that the steering motor 32 can generate.

The arbitration processing section 72 limits the change range of the torque command value T _p ^* calculated by the pinion angle feedback control section 63 based on the limit value T _L set by the limit value setting section 73 . When the absolute value of the torque command value T _p ^* exceeds the limit value _TL , the torque command value T _p ^* is limited to the limit value _TL . For example, when the torque command value T _p ^* is a positive value and the value of the torque command value T _p ^* exceeds the positive limit value T _L , the torque command value T _p ^* is limited to the positive limit value T _L be done. When the torque command value T _p ^* is a negative value, ^the torque command value T _p ^* is limited to the negative limit value T _L when the torque command value T _p * exceeds the negative limit value T _L. Therefore, the steering motor 32 is prevented from generating excessive torque based on the excessive torque command value T _p ^* that exceeds the limit value of the allowable range.

The arbitration processing unit 72 increases the absolute value of the limit value T _L when the steering force is likely to be insufficient, for example, when an excessive axial force is likely to be generated.
The arbitration processing unit 72 determines the final limit value T _L by multiplying the limit value T _L set by the limit value setting unit 73 by the gain _Gen , as expressed by the following equation (10), for example. calculate.

T _L (final) = T _L・G _en … (10)
However, the value of gain _Gen differs depending on the value of division F. The magnitude relationship of the gain G _en according to the value of the division F is as shown in equation (2) in the first embodiment.

In this way, when the steering force is likely to be insufficient, the final limit value T _L can be made larger than the normally used limit value T _L stored in the storage device. That is, the variation range of the torque command value T _p ^* is expanded according to the value of the gain G _en .

Incidentally, the arbitration processing unit 72 determines the final limit value T by adding the additional value T _se to the limit value T _L set by the limit value setting unit 73, as expressed by the following equation (11). Alternatively, _L may be calculated.

T _L (final) = T _L + T _se ... (11)
However, the value of the additional value T _se differs depending on the value of the classification F. The magnitude relationship of the additional value T _se according to the value of the division F is as shown in equation (4) in the first embodiment.

Even in this case, when the steering force is likely to be insufficient, the final limit value T _L can be made larger than the normally used limit value T _L stored in the storage device. That is, the variation range of the torque command value T _p ^* is expanded by the additional value T _se .

For example, if an excessive axial force is generated in the steering device 10, it becomes difficult to steer the steered wheels 12, as in the case where the steered wheels 12 hit a curb during stationary steering. At this time, the steering control unit 36 attempts to cause the steering _angle of the steered wheels 12 to follow the steering angle θ s of the steering wheel 11. Therefore, in order to supply a larger current to the steering motor 32, the steering control unit 36 calculates a larger torque command value T _p ^* that exceeds the limit value T _L stored in the storage device. There is a risk that

In this regard, in the present embodiment, when an excessive axial force is generated, the limit value T _L to be finally used is changed to a value larger than the limit value T _L stored in the storage device. The range of change in torque command value T _p ^* is expanded. This allows the torque command value T _p ^* to exceed the limit value T _L stored in the storage device. Therefore, the amount of current supplied to the steering motor 32 becomes larger than when the torque command value T _p ^* is limited to the limit value T _L stored in the storage device. Therefore, as the amount of current supplied to the steering motor 32 increases, the steering force generated by the steering motor 32 increases.

The reaction force control unit 27 executes a process for increasing the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, for example, as the notification process. The reaction force control section 27 increases the steering reaction force command value T ^* calculated by the steering reaction force command value calculation section 52 in the same manner as in the first embodiment. That is, the reaction force control unit 27 multiplies the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 by the gain G _rf , as expressed by the above equation (5). By doing so, the final steering reaction force command value T ^* is calculated.

Incidentally, similarly to the first embodiment, the reaction force control section 27 calculates the steering reaction force command value T calculated by the steering reaction force command value calculation section 52, as expressed by the above equation (6). The final steering reaction force command value T ^* may be calculated by adding the additional value T _rf to ^* .

<Effects of the third embodiment>
The third embodiment has the following effects.
(3-1) When the steering force is likely to be insufficient, the range of change of the torque command value T _p ^* calculated by the pinion angle feedback control unit 63 exceeds the limit value T _L that is its limit value. Expanded. Therefore, even if the torque command value T _p ^* exceeding the limit value T _L set by the limit value setting section 73 is calculated due to the generation of excessive axial force, for example, this torque command value T _p ^* is allowed. The steering motor 32 generates a larger steering force in accordance with the torque command value T _p ^* that exceeds the limit value _TL . In this way, by expanding the variation range of the torque command value T _p ^* in advance in preparation for a situation where an excessive axial force is generated, even if a large axial force is actually generated on the steered shaft 31, The steered wheels 12 can be smoothly steered without insufficient steering force.

(3-2) Furthermore, effects similar to those in columns (1-2) to (1-5) of the first embodiment can be obtained.
<Fourth embodiment>
Next, a fourth embodiment that embodies a steering device will be described. This embodiment differs from the third embodiment in that the energization control section 64 has the same processing function as the arbitration processing section 72 described above. In this embodiment, a configuration in which the above-mentioned arbitration processing section 72 is omitted is adopted as the steering control section 36.

As shown in FIG. 5(b), the energization control section 64 takes in the value of category F set by the determination section 71. Further, the energization control section 64 takes in the torque command value T _p ^* calculated by the pinion angle feedback control section 63 as the final torque command value T _p ^* .

The limit value setting section 73 sets a limit value _IL for limiting the range of change of the current command value I ^* calculated by the energization control section 64. The energization control section 64 takes in the limit value _IL set by the limit value setting section 73.

The energization control unit 64 increases the absolute value of the limit value _IL when the steering force is likely to be insufficient, for example, when an excessive axial force is likely to be generated.
The energization control unit 64 determines the final limit value I _L by multiplying the limit value T _L set by the limit value setting unit 73 by the gain G _en , as expressed by the following equation (11), for example. calculate.

I _L (final) = I _L・G _en … (11)
However, the value of gain _Gen differs depending on the value of division F. The magnitude relationship of the gain G _en according to the value of the division F is as shown in equation (2) in the first embodiment.

In this way, for example, in a situation where excessive axial force is likely to occur, it is possible to set the final limit value _IL to a value larger than the normally used limit value _IL stored in the storage device. can. That is, the change range of the current command value I ^* is expanded according to the value of the gain G _en . This allows the current command value I ^* to exceed the limit value _IL stored in the storage device. Therefore, the amount of current supplied to the steering motor 32 becomes larger than when the current command value I ^* is limited to the limit value _IL stored in the storage device. Therefore, as the amount of current supplied to the steering motor 32 increases, the steering force generated by the steering motor 32 increases.

Incidentally, the energization control unit 64 sets the final limit value I by adding the additional value I _se to the limit value I _L set by the limit value setting unit 73, as expressed by the following equation (12). Alternatively, _L may be calculated.

I _L (final) = I _L + I _se … (12)
However, the value of the additional value I _se differs depending on the value of the classification F. The magnitude relationship of the additional value I _se according to the value of the division F is as shown in equation (9) in the first embodiment.

Even with this method, for example, in a situation where excessive axial force is likely to occur, it is possible to set the final limit value I _L to a value larger than the normally used limit value I _L stored in the storage device. can. That is, the variation range of the current command value I ^* is expanded by the additional value _Ise .

The reaction force control unit 27 executes a process for increasing the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52, for example, as the notification process. The reaction force control section 27 increases the steering reaction force command value T ^* calculated by the steering reaction force command value calculation section 52 in the same manner as in the first embodiment. That is, the reaction force control unit 27 multiplies the steering reaction force command value T ^* calculated by the steering reaction force command value calculation unit 52 by the gain G _rf , as expressed by the above equation (5). By doing so, the final steering reaction force command value T ^* is calculated.

Note that, similarly to the first embodiment, the reaction force control section 27 calculates the steering reaction force command value T calculated by the steering reaction force command value calculation section 52, as expressed by the above equation (6). The final steering reaction force command value T ^* may be calculated by adding the additional value T _rf to ^* .

<Effects of the fourth embodiment>
The fourth embodiment has the following effects.
(4-1) When the steering force is likely to be insufficient, for example, when excessive axial force is likely to occur, the range of change of the current command value I ^* calculated by the energization control section 64 is at its limit value. It is expanded beyond a certain limit value _IL . Therefore, even if the current command value I _p ^* exceeding the limit value I _L set by the limit value setting unit 73 is calculated due to the generation of excessive axial force, for example, this current command value I ^* is allowed. The steering motor 32 generates a larger steering force in accordance with the current command value I ^* exceeding the limit value _IL . In this way, by expanding the change range of the current command value I ^* in advance in preparation for a situation where an excessive axial force is generated, even if a large axial force actually occurs on the steering shaft 31, it is possible to The steered wheels 12 can be smoothly steered without insufficient steering force.

(4-2) Furthermore, effects similar to those in columns (1-2) to (1-5) of the first embodiment can be obtained.
<Other embodiments>
Note that each embodiment may be modified and implemented as follows.

- In the first embodiment, when executing the boost-up process, the steering control unit 36 determines the degree of increase in the torque command value T _p ^* when the steering wheel 11 is steered by turning the steering wheel back. The degree of increase in the torque command value T _p ^* may be the same as when steering is performed.

- In each embodiment, the reaction force control unit 27, like the steering control unit 36 of the second embodiment, uses the steering reaction force command calculated by the steering reaction force command value calculation unit 52 as a notification process. The final current command value may be calculated by multiplying the current command value for the steering motor 32 calculated based on the value T ^* by a gain or by adding an additional value. The reaction force motor 22 controls power supply to the reaction force motor 22 according to the final current command value. Thereby, the steering reaction force during the period when the boost-up process is executed can be increased to a force larger than the steering reaction force during the normal time when the boost-up process is not executed.

- In each embodiment, the reaction force control unit 27 determines the degree of increase in the steering reaction force command value T ^* when the steering wheel 11 is turned back when performing the boost-up process. It may be made to be larger than the degree of increase in the steering reaction force command value T ^* when the steering reaction force command value T* is performed.

- In each embodiment, the reaction force control unit 27 may independently determine whether or not to execute the boost-up process.
- In each embodiment, the reaction force control unit 27 may control the torque generated by the reaction force motor 22 so as to vibrate the steering wheel 11 during the period when the boost-up process is executed.

- In each embodiment, the reaction force control section 27 and the steering control section 36 may constitute a single control section.
- In each embodiment, an example was given in which a so-called linkless structure in which power transmission between the steering shaft 21 and the steered wheels 12 is separated is adopted as the steering device 10 of the vehicle. A structure in which power transmission between the steered wheels 12 and the steered wheels 12 can be separated may be adopted. When the clutch is disconnected, power transmission between the steering wheel 11 and steered wheels 12 is disconnected. When the clutch is connected, power transmission between the steering wheel 11 and the steered wheels 12 is connected.

10... Steering device (control target)
DESCRIPTION OF SYMBOLS 11... Steering wheel 12... Steering wheel 22... Reaction force motor 31... Steering shaft 32... Steering motor 27... Reaction force control part (control part) which comprises a steering control device
36...Steering control unit (control unit) that constitutes the steering control device

Claims (6)

A steering shaft for steering steering wheels of a vehicle, the steering shaft configured to separate power transmission from the steering wheel;
a reaction force motor that generates a steering reaction force applied to the steering wheel;
A steering control device that controls a steering device including a steering motor that generates a torque applied to the steering shaft and a steering force for steering the steered wheels,
a control unit configured to calculate a first command value for the steering motor and a second command value for the reaction force motor according to a steering state of the steering wheel;
The control unit includes:
When the steering force is likely to be insufficient, a first process for increasing the first command value to a value larger than an original value according to a steering state of the steering wheel;
During the period in which the first process is executed, a second process for increasing the second command value to a value larger than an original value according to a steering state of the steering wheel is executed. A steering control device consisting of: The steering according to claim 1, wherein the control unit is configured to determine that the steering force is likely to be insufficient when the vehicle speed is in an extremely low speed range and the steering wheel is being steered. Control device. The control unit is configured to multiply the original second command value according to the steering state of the steering wheel by a gain or add an additional value as the second process. The steering control device according to claim 1 or claim 2. When executing the first process, the control unit determines the degree of increase in the first command value when the steering wheel is turned into the steering wheel, and the degree of increase in the first command value when the steering wheel is turned back into the steering wheel. The steering control device according to claim 1 or 2, configured to increase the degree of increase of the first command value to be greater than the degree of increase of the first command value. The control unit is configured to multiply the original first command value according to the steering state of the steering wheel by a gain or add an additional value as the first process. The steering control device according to claim 1 or claim 2. As the first process, the control unit adjusts the first command value by multiplying a limit value that limits a range of change of the first command value by a gain or by adding an additional value. 3. The steering control device according to claim 1, wherein the steering control device is configured to expand a range of change in the range of change.

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