JP7290529B2 - steering controller - Google Patents

Description

The present invention relates to a steering control device.

2. Description of the Related Art Conventionally, as a vehicle steering system, an electric power steering system (EPS) having an actuator using a motor as a driving source is known. Such an EPS acquires the steering angle of the steering wheel as an absolute angle including a range exceeding 360°, and performs various controls based on the steering angle. As an example of such control, for example, Japanese Patent Laid-Open No. 2004-100001 discloses a control that performs end contact mitigation control for reducing the impact of so-called end contact, in which the rack end, which is the end of the rack shaft, hits the rack housing. .

In the EPS of Patent Document 1, the rack end position where the movement of the rack shaft is physically restricted by the end contact is associated with the steering angle, and the same angle is stored as the end position correspondence angle. In the same EPS, by reducing the target value of the motor torque output by the motor according to the distance of the steering angle from the angle corresponding to the end position, the impact of the end contact is alleviated.

JP 2016-155519 A

By the way, depending on the specifications of the vehicle, for example, when the ignition is turned off or when the battery is replaced, the end position corresponding angle may disappear. If the end position correspondence angle disappears in this manner, for example, end contact mitigation control cannot be executed. Therefore, it is necessary to learn the end position correspondence angle, and at this time, it is required to accurately correspond the end position correspondence angle to the actual end angle at which the end contact actually occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering control device capable of learning an end position correspondence angle that accurately corresponds to an actual end angle.

A steering control device that solves the above problems includes a housing, a steering shaft that is reciprocatingly accommodated in the housing, and an actuator that uses a motor as a drive source to apply motor torque for reciprocating the steering shaft. An absolute steering angle represented by an absolute angle including a range exceeding 360°, which is a rotation angle of a rotating shaft that can be converted into a steering angle of a steerable wheel connected to the steering shaft, with the steering device provided as a control target. and an absolute steering angle detection unit for detecting the a restriction position determination angle acquisition unit that acquires a restriction position determination angle corresponding to an absolute steering angle; an end position corresponding angle setting unit that sets an end position corresponding angle associated with the absolute steering angle, and the restriction position determination angle acquisition unit obtains one of the restriction position determination angles, The other regulation position determination angles are not acquired until the surrounding environment change determination is established as to whether or not the environment has changed.

Here, for example, when the movement of the steered shaft is restricted because the steered wheels hit a curbstone, the restricted position determination angle acquired at this time is an angle that deviates from the actual end angle. Therefore, if the end position corresponding angle is set based only on the single regulation position determination angle, the end position corresponding angle tends to deviate from the actual end angle. Therefore, it is conceivable to set the end position correspondence angle based on a plurality of regulation position determination angles. As a result, for example, even if one of the plurality of regulation position determination angles is obtained when hitting a curbstone, if the other regulation position determination angles are obtained when hitting the end, the end position corresponding angle is the actual end. It is possible to prevent the angle from deviating from the corner. However, for example, when a plurality of end position corresponding angles are obtained when hitting a curbstone, even if the end position corresponding angle is set based on a plurality of regulation position determination angles, the end position corresponding angle is not the actual end position. There is a possibility that the angle deviates from the corner.

In this respect, according to the above configuration, another regulation position determination angle is acquired after the surrounding environment of the vehicle changes after setting one regulation position determination angle. Therefore, it is possible to prevent all of the plurality of restriction position determination angles from becoming data acquired when the movement of the steering shaft is restricted due to hitting a curb or the like. As a result, it is possible to set the end position correspondence angle that accurately corresponds to the actual end angle.

In the steering control device described above, it is preferable that the conditions under which the surrounding environment change determination is established include that the steering amount to be returned to the steering wheel is equal to or greater than the threshold value for determination of the return to steering.
According to the above configuration, the condition for determining whether the surrounding environment has changed includes that the steering back is performed, so it is possible to suitably determine whether or not the surrounding environment has changed.

In the above steering control device, it is preferable that the conditions under which the surrounding environment change determination is established include that the vehicle speed is equal to or higher than a running threshold value indicating that the vehicle is in a non-stop state.
According to the above configuration, since the vehicle is running in the conditions for determining the change in the surrounding environment, it is possible to suitably determine whether or not the surrounding environment has changed.

In the steering control device described above, the regulation position determination angle acquisition unit determines whether the vehicle speed is equal to or lower than a low speed threshold indicating that the vehicle is traveling at a low speed, regardless of whether or not the signal indicating the vehicle speed input from the vehicle speed sensor is normal. In the case of (1), it is determined whether or not the movement of the steering shaft is restricted. When the signal indicating the vehicle speed is abnormal, the condition for determining the change in the surrounding environment is met. It is preferable not to include the vehicle speed being greater than the running threshold.

According to the above configuration, even if there is an abnormality in the signal indicating the vehicle speed input from the vehicle speed sensor, the regulation position determination angle can be acquired, so the end position corresponding angle can be set early. Further, when the signal indicating the vehicle speed is abnormal, the comparison of the vehicle speed and the driving threshold is not included in the determination of the change in the surrounding environment. can be prevented.

In the above steering control device, the restriction position determination angle acquisition unit performs dynamic restriction determination and static restriction determination, and when either one of the dynamic restriction determination and the static restriction determination is established, It is determined that the movement of the steering shaft is restricted, and the sign of the steering torque for moving the steering shaft in one direction and the sign of the rotation direction of the motor are positive, and the direction opposite to the one direction. When the sign of the steering torque for moving the steering shaft and the sign of the rotation direction of the motor are negative, the condition for the dynamic regulation determination to be satisfied is that the absolute value of the steering torque is the first steering and the sign of the angular velocity change amount, which is the amount of change in the angular velocity of the motor, is opposite to the sign of the steering torque, and the absolute value of the angular velocity change amount is greater than the first angular velocity change amount threshold. The conditions for the static regulation determination to be satisfied include that the absolute value of the steering torque is equal to or greater than a second steering torque threshold that is larger than the first steering torque threshold, and that the absolute value of the angular velocity change amount It is preferable that the value is less than or equal to a second angular velocity variation threshold that is smaller than the first angular velocity variation threshold.

According to the above configuration, when the movement of the steering shaft is restricted in various manners, it is possible to acquire the restriction position determination angle and quickly set the end position correspondence angle. Here, for example, it is assumed that the turning steering is performed quickly, and after the steered wheels hit a curb or the like and the movement of the steering shaft is restricted, the turning steering is continued. In this case, both the dynamic restriction determination and the static restriction determination can be established. Therefore, if the restriction position determination angle is acquired when each determination is satisfied, both of the two restriction position determination angles are the same. This is the data when the movement of the rudder shaft is restricted by hitting the curb. Therefore, in the configuration for performing dynamic restriction determination and static restriction determination, after one restriction position determination angle is set as in the above configuration, another restriction position determination angle is set after the surrounding environment of the vehicle changes. The effect obtained is large.

According to the present invention, it is possible to learn the end position corresponding angle that accurately corresponds to the actual end angle.

1 is a schematic configuration diagram of an electric power steering device; FIG. FIG. 2 is a block diagram of a steering control device; FIG. 2 is a block diagram of a limit value setting unit; FIG. 4 is a block diagram of an end position correspondence angle management unit; FIG. 4 is a schematic diagram showing the relationship between the absolute steering angle and the pinion shaft torque; 4 is a flowchart showing a processing procedure for obtaining a regulation position determination angle by a regulation position determination angle acquisition unit; 4 is a flowchart showing a processing procedure of dynamic restriction determination by a restriction position determination angle acquisition unit; 4 is a flowchart showing a processing procedure of static restriction determination by a restriction position determination angle acquisition unit; 4 is a flow chart showing a processing procedure for determining a change in the surrounding environment by a regulation position determination angle acquisition unit;

An embodiment of a steering control device will be described below with reference to the drawings.
As shown in FIG. 1, an electric power steering system (EPS) 2 serving as a steering system to be controlled by a steering control system 1 is a steering mechanism that turns steerable wheels 4 based on the operation of a steering wheel 3 by a driver. 5. The EPS 2 also includes an EPS actuator 6 as an actuator that applies an assist force to the steering mechanism 5 to assist the steering operation.

The steering mechanism 5 includes a steering shaft 11 to which the steering wheel 3 is fixed, a rack shaft 12 as a steering shaft connected to the steering shaft 11, and a rack housing as a housing through which the rack shaft 12 is reciprocally inserted. 13 and a rack and pinion mechanism 14 that converts the rotation of the steering shaft 11 to the rack shaft 12 . The steering shaft 11 is constructed by connecting a column shaft 15, an intermediate shaft 16, and a pinion shaft 17 in order from the side where the steering wheel 3 is located.

The rack shaft 12 and the pinion shaft 17 are arranged in the rack housing 13 with a predetermined crossing angle. The rack-and-pinion mechanism 14 is configured by engaging rack teeth 12 a formed on the rack shaft 12 and pinion teeth 17 a formed on the pinion shaft 17 . Further, tie rods 19 are rotatably connected to both ends of the rack shaft 12 through rack ends 18 formed of ball joints provided at the ends of the shaft. The tip of the tie rod 19 is connected to a knuckle (not shown) to which the steered wheels 4 are assembled. Therefore, in the EPS 2, rotation of the steering shaft 11 accompanying steering operation is converted into axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckles via the tie rods 19. The steered angle of the steered wheels 4, that is, the traveling direction of the vehicle is changed.

The position of the rack shaft 12 where the rack end 18 abuts the left end of the rack housing 13 is the maximum rightward steering position, and this position corresponds to the rack end position as the right end position. The position of the rack shaft 12 where the rack end 18 abuts the right end of the rack housing 13 is the position at which the leftward steering can be maximized, and this position corresponds to the rack end position as the left end position.

The EPS actuator 6 includes a motor 21 as a drive source and a speed reduction mechanism 22 such as a worm and wheel. A motor 21 is connected to the column shaft 15 via a speed reduction mechanism 22 . The EPS actuator 6 decelerates the rotation of the motor 21 by the deceleration mechanism 22 and transmits it to the column shaft 15 , thereby applying the motor torque to the steering mechanism 5 as an assist force. A three-phase brushless motor is adopted as the motor 21 of this embodiment.

The steering control device 1 is connected to a motor 21 and controls its operation. The steering control device 1 includes a central processing unit (CPU) and a memory (not shown), and the CPU executes a program stored in the memory at predetermined calculation cycles. As a result, various controls are executed.

The steering control device 1 is connected to a vehicle speed sensor 31 for detecting the vehicle speed SPD of the vehicle and a torque sensor 32 for detecting the steering torque Th applied to the steering shaft 11 by steering by the driver. Further, the steering control device 1 is connected with a rotation sensor 33 for detecting the rotation angle .theta.m of the motor 21 as a relative angle within the range of 360.degree. The steering torque Th and the rotation angle .theta.m are detected as positive values when the vehicle is steered to the right, and as negative values when the vehicle is steered to the left. That is, in the present embodiment, the sign of the steering torque Th for moving the rack shaft 12 in the right direction corresponding to one direction and the sign of the rotation direction of the motor 21 are both positive, and the left direction corresponding to the opposite direction to the one direction. The sign of the steering torque Th for moving the rack shaft 12 and the sign of the rotational direction of the motor 21 are both negative. The steering control device 1 supplies driving power to the motor 21 based on the signals indicating the state quantities input from these sensors, thereby operating the EPS actuator 6 , that is, the steering mechanism 5 and the rack shaft 12 . controls the assist force applied to reciprocate the .

Next, the configuration of the steering control device 1 will be described.
As shown in FIG. 2, the steering control device 1 includes a microcomputer 41 that outputs a motor control signal Sm, and a drive circuit 42 that supplies drive power to the motor 21 based on the motor control signal Sm. A well-known PWM inverter having a plurality of switching elements such as FETs is employed in the drive circuit 42 of the present embodiment. A motor control signal Sm output from the microcomputer 41 defines the ON/OFF state of each switching element. As a result, each switching element is turned on and off in response to the motor control signal Sm, and the energization pattern to the motor coil of each phase is switched. output to

Each control block shown below is realized by a computer program executed by the microcomputer 41, detects each state quantity at a predetermined sampling period, and indicates each control block below at each predetermined calculation period. Each calculation process is executed.

The vehicle speed SPD, the steering torque Th, and the rotation angle .theta.m of the motor 21 are inputted to the microcomputer 41. FIG. Further, the microcomputer 41 receives the phase current values Iu, Iv, Iw of the motor 21 detected by the current sensor 44 and the power supply voltage Vb of the vehicle power supply 43 detected by the voltage sensor 45 . The current sensors 44 are provided on connection lines 46 between the drive circuit 42 and the motor coils of each phase. The voltage sensor 45 is provided on a connection line 47 between the vehicle-mounted power source 43 and the drive circuit 42 . In addition, in FIG. 2, for convenience of explanation, the current sensors 44 of each phase and the connection lines 46 of each phase are shown together as one. Then, the microcomputer 41 outputs a motor control signal Sm based on these state quantities.

Specifically, the microcomputer 41 includes a current command value calculator 51 that calculates current command values Id* and Iq*, and a motor control signal generator 52 that outputs a motor control signal Sm based on the current command values Id* and Iq*. and an absolute steering angle detector 53 for detecting the absolute steering angle θs.

The steering torque Th, the vehicle speed SPD, and the absolute steering angle θs are input to the current command value calculator 51 . The current command value calculator 51 calculates current command values Id* and Iq* based on these state quantities. Current command values Id* and Iq* are target values of the current to be supplied to the motor 21, and indicate current command values on the d-axis and q-axis in the d/q coordinate system, respectively. Of these, the q-axis current command value Iq* indicates the target value of the motor torque that the motor 21 outputs. In this embodiment, the d-axis current command value Id* is basically fixed at zero. The current command values Id* and Iq* are, for example, positive values when assisting rightward steering, and negative values when assisting leftward steering.

The current command values Id*, Iq*, the phase current values Iu, Iv, Iw, and the rotation angle θm of the motor 21 are input to the motor control signal generator 52 . The motor control signal generator 52 generates the motor control signal Sm by executing current feedback control in the d/q coordinate system based on these state quantities.

Specifically, the motor control signal generator 52 maps the phase current values Iu, Iv, and Iw onto the d/q coordinate system based on the rotation angle θm, thereby determining the actual state of the motor 21 in the d/q coordinate system. A d-axis current value Id and a q-axis current value Iq, which are current values, are calculated. Then, the motor control signal generator 52 performs current feedback so that the d-axis current value Id follows the d-axis current command value Id* and the q-axis current value Iq follows the q-axis current command value Iq*. A motor control signal Sm is generated by performing control. Note that the q-axis current value Iq calculated in the process of generating the motor control signal Sm is output to the current command value calculator 51 .

The motor control signal generator 52 outputs the motor control signal Sm thus generated to the drive circuit 42 . As a result, the motor 21 is supplied with drive power corresponding to the motor control signal Sm, and motor torque corresponding to the q-axis current command value Iq* is output from the motor 21, thereby providing an assist force to the steering mechanism 5. Granted.

The rotation angle θm is input to the absolute steering angle detection unit 53 . The absolute steering angle detection unit 53 detects the motor absolute angle represented by an absolute angle including a range exceeding 360° based on the rotation angle θm. The absolute steering angle detection unit 53 of the present embodiment integrates the number of rotations of the motor 21 with the rotation angle θm when the start switch such as the ignition switch is turned on for the first time after the replacement of the vehicle power supply 43, for example, as the origin. The motor absolute angle is detected based on the number and the rotation angle θm. The absolute steering angle detector 53 multiplies the motor absolute angle by a conversion factor based on the speed reduction ratio of the speed reduction mechanism 22 to detect the absolute steering angle θs indicating the steering angle of the steering shaft 11 . In the steering control device 1 of the present embodiment, the presence or absence of rotation of the motor 21 is monitored even when the start switch is turned off, and the number of rotations of the motor 21 is constantly integrated. As a result, even when the start switch is turned on for the second time after the onboard power source 43 is replaced, the origin of the absolute steering angle θs becomes the same as the origin set when the start switch is turned on for the first time.

Since the steering angle of the steerable wheels 4 is changed by the rotation of the steering shaft 11 as described above, the absolute steering angle θs indicates the rotation angle of the rotary shaft that can be converted into the steering angle of the steerable wheels 4. . Also, the motor absolute angle and the absolute steering angle .theta.s are assumed to have a positive value when the rotation angle is in the right direction from the origin, and a negative value when the rotation angle is in the left direction.

Next, the configuration of the current command value calculator 51 will be described in detail.
A current command value calculator 51 includes an assist command value calculator 61 that calculates an assist command value Ias*, which is a basic component of the q-axis current command value Iq*, and an assist command value calculator 61 that calculates the upper limit of the absolute value of the q-axis current command value Iq*. A limit value setting unit 62 for setting the limit value Ig and a guard processing unit 63 for limiting the absolute value of the assist command value Ias* to the limit value Ig or less are provided. The current command value calculation unit 51 also includes an end position corresponding angle management unit 65 that manages the end position corresponding angles θs_le and θs_re that are the absolute steering angles θs corresponding to the left and right rack end positions stored in the memory 64 . there is

The steering torque Th and the vehicle speed SPD are input to the assist command value calculator 61 . The assist command value calculator 61 calculates an assist command value Ias* based on the steering torque Th and the vehicle speed SPD. Specifically, the assist command value calculation unit 61 calculates the assist command value Ias* having a larger absolute value as the absolute value of the steering torque Th increases and as the vehicle speed SPD decreases. The assist command value Ias* calculated in this manner is output to the guard processing unit 63 .

In addition to the assist command value Ias*, the limit value Ig set by the limit value setting unit 62 as described later is input to the guard processing unit 63 . When the absolute value of the input assist command value Ias* is equal to or less than the limit value Ig, the guard processing unit 63 uses the value of the assist command value Ias* as it is as the q-axis current command value Iq*, and the motor control signal generating unit 52 output to On the other hand, when the absolute value of the input assist command value Ias* is larger than the limit value Ig, the q-axis current command value Iq* is obtained by limiting the absolute value of the assist command value Ias* to the value of the limit value Ig. is output to the motor control signal generator 52 as.

The memory 64 stores the rated current Ir as the maximum current corresponding to the torque preset as the motor torque that the motor 21 can output, the end position corresponding angles θs_le, θs_re, and the like. The left end position corresponding angle θs_le is the absolute steering angle θs corresponding to the left rack end position, and the right end position corresponding angle θs_re is the absolute steering angle θs corresponding to the right rack end position. The settings of the end position corresponding angles θs_le and θs_re are managed by the end position corresponding angle management unit 65 as described later. It should be noted that the memory 64 of this embodiment is of a type that retains the end position corresponding angles θs_le and θs_re unless the onboard power supply 43 is removed, for example.

Next, the configuration of the limit value setting unit 62 will be described.
The absolute steering angle θs, vehicle speed SPD, power supply voltage Vb, rated current Ir, and end position corresponding angles θs_le and θs_re are input to the limit value setting unit 62 . Then, the limit value setting unit 62 sets the limit value Ig based on these state quantities.

Specifically, as shown in FIG. 3, the limit value setting unit 62 includes a steering angle limit value calculation unit 71 that calculates a steering angle limit value Ien based on the absolute steering angle θs, and another limit value based on the power supply voltage Vb. and a minimum value selection unit 73 for selecting the smaller one of the steering angle limit value Ien and the voltage limit value Ivb.

The absolute steering angle θs, the vehicle speed SPD, the rated current Ir, and the end position corresponding angles θs_le and θs_re are input to the steering angle limit value calculator 71 . Based on these state quantities, the steering angle limit value calculation unit 71 determines that the end separation angle Δθ indicating the minimum distance from the left and right end position corresponding angles θs_le and θs_re of the absolute steering angle θs is equal to or less than a predetermined angle θ1, as will be described later. , the steering angle limit value Ien is calculated which decreases as the end separation angle .DELTA..theta. decreases. The steering angle limit value Ien calculated in this manner is output to the minimum value selection section 73 . Note that the steering angle limit value calculation unit 71 does not calculate the steering angle limit value Ien when none of the left and right end position corresponding angles θs_le and θs_re are set in the memory 64 .

A power supply voltage Vb is input to the voltage limit value calculator 72 . The voltage limit value calculator 72 calculates a voltage limit value Ivb smaller than the rated voltage for supplying the rated current Ir when the absolute value of the power supply voltage Vb becomes equal to or less than a preset voltage threshold Vth. Specifically, when the absolute value of the power supply voltage Vb becomes equal to or less than the voltage threshold value Vth, the voltage limit value calculation unit 72 calculates the voltage limit value having a smaller absolute value based on the decrease in the absolute value of the power supply voltage Vb. Compute Ivb. The voltage limit value Ivb calculated in this manner is output to the minimum value selection unit 73 .

The minimum value selection unit 73 selects the smaller one of the input steering angle limit value Ien and voltage limit value Ivb as the limit value Ig and outputs it to the guard processing unit 63 .
The absolute value of the q-axis current command value Iq* is limited to the steering angle limit value Ien by outputting the steering angle limit value Ien to the guard processing unit 63 as the limit value Ig. As a result, when the end separation angle Δθ is equal to or less than the predetermined angle θ1, the absolute value of the q-axis current command value Iq* is decreased based on the decrease in the end separation angle Δθ, so that the rack end 18 is shifted to the rack housing 13. End contact mitigation control is executed to reduce the impact of the end contact that hits. As will be described later, when both the left and right end position corresponding angles θs_le and θs_re are stored in the memory 64, normal end contact relaxation control is performed, and either the left or right end position corresponding angles θs_le and θs_re are stored in the memory 64. The case in which it is stored is provisional end contact mitigation control.

Also, the absolute value of the q-axis current command value Iq* is limited to the voltage limit value Ivb by outputting the voltage limit value Ivb to the guard processing unit 63 as the limit value Ig. As a result, when the absolute value of the power supply voltage Vb becomes equal to or lower than the voltage threshold Vth, power supply protection control is executed to reduce the absolute value of the q-axis current command value Iq* based on the decrease in the absolute value of the power supply voltage Vb. be.

Next, the configuration of the steering angle limit value calculator 71 will be described.
The steering angle limit value calculation unit 71 includes an end separation angle calculation unit 81 that calculates an end separation angle Δθ, and an angle limit component calculation unit 82 that calculates an angle limit component Iga that is a current limit amount determined according to the end separation angle Δθ. and Then, the steering angle limit value calculator 71 calculates the steering angle limit value Ien by subtracting the angle limit component Iga from the rated current Ir.

Specifically, the end separation angle calculator 81 receives the absolute steering angle θs and the end position corresponding angles θs_le and θs_re. When both the left and right end position corresponding angles θs_le and θs_re are stored in the memory 64, the end separation angle calculator 81 calculates the absolute steering angle θs and the left end position corresponding angle θs_le in the latest calculation cycle. and the difference between the absolute steering angle θs and the right end position corresponding angle θs_re at the latest calculation cycle. Then, the end separation angle calculator 81 outputs the smaller absolute value of the calculated differences to the angle limit component calculation unit 82 as the end separation angle Δθ. On the other hand, when the memory 64 stores only one of the left and right end position corresponding angles θs_le and θs_re, the end separation angle calculator 81 calculates the absolute steering angle θs and the end position corresponding angle Calculate the difference between θs_le or the end position corresponding angle θs_re. Then, the end separation angle calculation section 81 outputs this difference to the angle limit component calculation section 82 as the end separation angle Δθ.

Note that the end separation angle calculator 81 does not calculate the end separation angle Δθ when neither of the left and right end position corresponding angles θs_le and θs_re are stored in the memory 64 . As a result, the angle limit component Iga is not calculated and the steering angle limit value Ien is not calculated in the angle limit component calculator 82, which will be described later.

The end separation angle Δθ and the vehicle speed SPD are input to the angle limit component calculator 82 . The angle limit component calculator 82 has a map that defines the relationship between the end separation angle Δθ and the vehicle speed SPD and the angle limit component Iga. Calculate the limiting component Iga.

In this map, the angle limiting component Iga decreases in proportion to the increase in the end separation angle Δθ from the zero state, reaches zero at the predetermined angle θ1, and increases from the predetermined angle θ1. is set to zero when the In addition, in this map, a region where the end separation angle Δθ is negative is also set. After reaching the same value, it becomes constant. The negative area in the map assumes that the EPS 2 is elastically deformed and the motor 21 rotates due to further cutting steering from the state in which the rack end 18 is in contact with the rack housing 13 . The predetermined angle θ1 is set to a small angle that indicates a range near the end position corresponding angles θs_le and θs_re. That is, the angle limiting component Iga decreases as the absolute steering angle θs moves from the end position corresponding angles θs_le and θs_re toward the steering neutral side. set to zero.

Further, this map is set so that the angle limiting component Iga becomes smaller as the vehicle speed SPD increases in a region where the end separation angle Δθ is equal to or less than the predetermined angle θ1. Specifically, when the vehicle speed SPD is in the low speed range, the angle limiting component Iga is greater than zero, but when the vehicle speed SPD is in the middle to high speed range, the angle limiting component Iga is set to zero. . The angle limiting component Iga calculated in this way is output to the subtractor 83 .

The subtractor 83 receives the rated current Ir in addition to the angle limiting component Iga. The steering angle limit value calculator 71 outputs a value obtained by subtracting the angle limit component Iga from the rated current Ir in the subtractor 83 to the minimum value selector 73 as the steering angle limit value Ien.

Next, the configuration of the end position correspondence angle management unit 65 will be described.
As shown in FIG. 2, the vehicle speed SPD, the steering torque Th, the absolute steering angle θs, the q-axis current value Iq, and the motor angular velocity ωm obtained by differentiating the rotation angle θm are input to the end position corresponding angle management section 65. be done. Based on these state quantities, the end position correspondence angle management unit 65 determines whether the movement of the rack shaft 12 to either the left or right is restricted, and determines that the movement of the rack shaft 12 is restricted. A plurality of regulation position determination angles θi corresponding to the absolute steering angle θs at the time of determination are acquired. Then, the end position correspondence angle management unit 65 stores the end position correspondence angles θs_le and θs_re in the memory 64 based on the plurality of regulation position determination angles θi. After temporarily storing the end position corresponding angles θs_le and θs_re in the memory 64, the end position corresponding angle managing unit 65 does not execute the processing related to the setting of the end position corresponding angles θs_le and θs_re until these disappear. .

Specifically, as shown in FIG. 4 , the end position corresponding angle management unit 65 includes an angular velocity change amount calculation unit 91 , a regulation position determination angle acquisition unit 92 , and an end position corresponding angle setting unit 93 .
The motor angular velocity ωm is input to the angular velocity variation calculator 91 . The angular velocity change amount calculator 91 calculates an angular velocity change amount Δωm, which is the amount of change, based on the input motor angular velocity ωm. Then, the angular velocity change amount calculation section 91 outputs the angular velocity change amount Δωm to the restriction position determination angle acquisition section 92 . Note that the angular velocity change amount calculator 91 of the present embodiment outputs the angular velocity change amount Δωm subjected to low-pass filter processing to the regulation position determination angle acquisition unit 92 .

The vehicle speed SPD, the steering torque Th, the q-axis current value Iq, the motor angular velocity ωm, the angular velocity change amount Δωm, and the absolute steering angle θs are input to the regulation position determination angle acquisition unit 92 . As will be described later, the restriction position determination angle acquisition unit 92 determines whether the movement of the rack shaft 12 to either the left or the right is restricted based on these state quantities, and determines whether the movement of the rack shaft 12 is restricted. A regulation position determination angle θi corresponding to the absolute steering angle θs when it is determined that the steering angle is determined to be obtained.

A plurality of restriction position determination angles θi are input from the restriction position determination angle acquisition unit 92 to the end position corresponding angle setting unit 93 . When the end position correspondence angle setting unit 93 acquires the left and right regulation position determination angles θi, it sets the end position correspondence angles θs_le and θs_re based on these left and right regulation position judgment angles θi. Based on the sign of the regulation position determination angle θi, the end position corresponding angle setting unit 93 determines whether the regulation position determination angle θi is one of the left side and the right side.

Specifically, when the end position correspondence angle setting unit 93 acquires the left and right restriction position determination angles θi, first, the absolute value of the left restriction position determination angle θi and the absolute value of the right restriction position determination angle θi are calculated. Calculate the stroke width Wma, which is the sum. Then, when the stroke width Wma is larger than the stroke threshold value Wth, the end position corresponding angle setting unit 93 sets the obtained left and right regulation position determination angles θi as they are as the end position corresponding angles θs_le and θs_re, respectively. It should be noted that the stroke threshold value Wth is set within the angular range indicated by the absolute steering angle θs, which is slightly smaller than the angular range corresponding to the entire stroke range of the rack shaft 12 . When the stroke width Wma is equal to or less than the stroke threshold value Wth, the end position correspondence angle setting unit 93 does not set the end position correspondence angles θs_le and θs_re, discards the input restriction position determination angle θi, and sets both left and right restriction angles. Similar processing is performed when the position determination angle θi is acquired again.

On the other hand, when the end position corresponding angle setting unit 93 acquires a plurality of restriction position determination angles θi for only one of the left side and the right side, the end position corresponding angle θs_le, Set only θs_re. Specifically, the end position correspondence angle setting unit 93 sets the average value of the plurality of regulation position determination angles θi as the left end position correspondence angle θs_le or the right end position correspondence angle θs_re.

Next, acquisition of the restriction position determination angle θi by the restriction position determination angle acquisition unit 92 will be described.
If the signal indicating the vehicle speed SPD input from the vehicle speed sensor 31 is normal and the vehicle speed SPD is greater than the low speed threshold value Slo, the restriction position determination angle acquisition unit 92 determines whether the movement of the rack shaft 12 is restricted. No decision is made. This is because when the vehicle speed SPD is relatively high, when the steering wheel 3 is steered to the rack end position, the vehicle spins or the like, and the end hit does not occur. For example, when the vehicle speed SPD becomes an unacceptable value, or when the amount of change from the previous value exceeds a preset threshold value, the regulation position determination angle acquisition unit 92 determines that the signal indicating the vehicle speed SPD is abnormal. I judge. The low speed threshold Slo is a vehicle speed indicating that the vehicle is traveling at a low speed, and is set in advance.

The restriction position determination angle acquisition unit 92 performs dynamic restriction determination when the signal indicating the vehicle speed SPD is abnormal or when the vehicle speed SPD is equal to or lower than the low speed threshold value Slo. Then, the restriction position determination angle acquisition unit 92 determines whether the dynamic restriction determination is performed continuously for the first predetermined time period, and when the dynamic restriction determination is continuously satisfied for the first predetermined time period, the restriction position determination angle obtaining unit 92 determines whether the restriction position is determined according to the absolute steering angle θs when the dynamic restriction determination is continuously satisfied for the first predetermined time period. Acquire the position determination angle θi. On the other hand, when the dynamic restriction determination is not established, the restriction position determination angle acquisition section 92 performs static restriction determination. Then, when the static regulation determination is continuously established for the second predetermined period of time, the regulation position determination angle obtaining section 92 determines whether or not the static regulation determination is established according to the absolute steering angle θs when the static regulation determination is continuously established for the second predetermined period of time. Acquire the position determination angle θi.

The static restriction determination is a determination for detecting a state in which the rack shaft 12 is held while movement is restricted, and a state in which the movement of the rack shaft 12 is restricted by slow turning steering. be. The dynamic restriction determination is a determination for detecting a state in which steering is performed at a relatively high speed and steering is performed in reverse immediately after movement of the rack shaft 12 is restricted.

The restriction position determination angle acquisition unit 92 of the present embodiment obtains the absolute steering angle θs when determining that the movement of the rack shaft 12 is restricted as a result of dynamic restriction determination or static restriction determination. Rigidity compensation is performed based on the mechanical elastic deformation of the EPS 2 caused by the applied torque, and the angle after the stiffness compensation is acquired as the regulation position determination angle θi.

In addition, the restriction position determination angle acquisition unit 92 acquires one restriction position determination angle θi until it is determined whether or not the surrounding environment of the vehicle has changed. Do not get the angle θi.

The processing performed by the restriction position determination angle acquisition unit 92 will be described in detail below in the order of dynamic restriction determination, static restriction determination, stiffness compensation, and ambient environment change determination.
(Dynamic regulation decision)
When the following three conditions are satisfied, the restriction position determination angle acquisition unit 92 determines that the dynamic restriction determination is satisfied and the movement of the rack shaft 12 is restricted.

(a1) The absolute value of the steering torque Th is greater than or equal to the first steering torque threshold Tth1.
(a2) The sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1.

(a3) The sign of the angular velocity variation Δωm is opposite to the sign of the steering torque Th, and the absolute value of the angular velocity variation Δωm is greater than the first angular velocity variation threshold Δωth1.
Note that the first steering torque threshold Tth1 is a steering torque when the steering is reversed immediately after the rack end 18 comes into contact with the rack housing 13, and is set to an appropriate value greater than zero. The first angular velocity threshold ωth1 is an angular velocity indicating that the motor 21 is stopped, and is set to substantially zero. The first angular velocity change amount threshold value Δωth1 is an angular velocity change amount indicating that the motor 21 is rapidly decelerating, and is set to a relatively large value.

(Static regulation judgment)
When the following three conditions are satisfied, the restriction position determination angle acquisition section 92 determines that the static restriction determination is satisfied and the movement of the rack shaft 12 is restricted.

(b1) The absolute value of the steering torque Th is equal to or greater than the second steering torque threshold Tth2.
(b2) The sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and less than or equal to the second angular velocity threshold ωth2.

(b3) The absolute value of the angular velocity variation Δωm is less than the second angular velocity variation threshold Δωth2.
The second steering torque threshold value Tth2 is the steering torque required to hold the steering wheel 3 when the vehicle turns while the rack end 18 is in contact with the rack housing 13, and is the first steering torque. It is set to an appropriate value larger than the threshold Tth1. The second angular velocity threshold ωth2 is an angular velocity indicating that the motor 21 is rotating at a low speed, and is set to an appropriate value greater than zero. The second angular velocity change amount threshold Δωth2 is an angular velocity change amount indicating that the motor 21 is not substantially accelerating or decelerating, and is set to a value smaller than the first angular velocity change amount threshold Δωth1 and slightly larger than zero. there is

(stiffness compensation)
The restriction position determination angle acquisition unit 92 obtains a value obtained by subtracting the mechanical elastic deformation occurring in the EPS 2 from the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted, as the restriction position determination angle θi. to get as

Specifically, the restriction position determination angle acquisition unit 92 calculates the pinion shaft torque Tp, which is the total torque applied to the EPS 2 when it is determined that the movement of the rack shaft 12 is restricted. The pinion shaft torque Tp corresponds to the axial force acting on the rack shaft 12 . As shown in the following equation (1), the regulation position determination angle acquisition unit 92 of the present embodiment obtains the steering torque Th applied to the driver, the motor torque based on the q-axis current value Iq, and the change in the angular velocity of the motor 21. The pinion shaft torque Tp is calculated using the inertia torque based on the quantity Δωm.

Tp=Th+Iq×Km+Δωm×Kω (1)
"Km" indicates a coefficient determined by the motor constant of the motor 21, the reduction ratio and efficiency of the speed reduction mechanism 22, and the like. "Kω" indicates a coefficient determined by the moment of inertia of the motor 21, the reduction ratio and efficiency of the speed reduction mechanism 22, and the like.

Here, as shown in FIG. 5, when the driver normally performs a steering operation, the steerable wheels 4 are steered according to the pinion shaft torque Tp applied to the EPS 2, and the absolute steering angle .theta.s increases. When the absolute steering angle .theta.s corresponding to the actual rack end position is slightly exceeded, the absolute steering angle .theta.s hardly increases even if the pinion shaft torque Tp increases. This is because the movement of the rack shaft 12 is restricted by the end abutment, and the pinion shaft torque Tp increases. This is because the motor 21 only rotates slightly. Since the inclination of the pinion shaft torque Tp with respect to the absolute steering angle θs is proportional to the elastic coefficient Ke of the EPS 2, the absolute steering angle θs substantially coincides with the actual rack end position.

Based on this fact, the regulation position determination angle acquisition unit 92 calculates the rotation angle of the motor 21 based on the elastic deformation amount of the EPS2 by multiplying the elastic coefficient Ke of the EPS2 by the pinion shaft torque Tp. Then, the regulation position determination angle acquisition unit 92 acquires, as the regulation position determination angle θi, a value obtained by subtracting the rotation angle from the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted.

(surrounding environment change determination)
When the following two conditions are satisfied, the regulation position determination angle acquisition unit 92 determines that the surrounding environment change determination is established and that the surrounding environment of the vehicle has changed. However, if the signal indicating the vehicle speed SPD is abnormal, the regulation position determination angle acquisition unit 92 does not determine whether the condition (c2) is satisfied, and if the condition (c1) is satisfied, , it is determined that the surrounding environment change determination is established.

(c1) The return steering amount θba is greater than or equal to the return determination threshold value θth.
(c2) When the signal indicating the vehicle speed SPD input from the vehicle speed sensor 31 is normal, the vehicle speed SPD is greater than or equal to the travel threshold Smin.

Note that the steering-back steering amount θba is the difference between the latest regulation position determination angle θi and the absolute steering angle θs. The steering-back determination threshold value θth is an angle at which the driver is considered to have performed the steering-back steering, and is set in advance to a relatively large value such as about 100°, for example. The running threshold Smin is the minimum vehicle speed indicating that the vehicle is running without stopping, and is preset to a value greater than zero and smaller than the low speed threshold Slo.

(flowchart)
Next, an example of a processing procedure performed by the regulation position determination angle acquisition unit 92 will be described with reference to flowcharts shown in FIGS. 6 to 9. FIG. For convenience of explanation, the case where the rack shaft 12 moves to the right and the right regulation position determination angle θi is obtained will be described below. Similar processing is performed when obtaining θi.

As shown in FIG. 6, when obtaining the restriction position determination angle θi, the restriction position determination angle acquisition unit 92 acquires various state quantities (step 101), and is permitted to acquire the restriction position determination angle θi. It is determined whether or not a permission flag indicating that is set (step 102). Note that the permission flag is set in the initial state, and is reset when the regulation position determination angle θi is obtained. The permission flag is set again when the peripheral environment change determination is established in the reset state.

If the permission flag is not set (step 102: NO), the regulation position determination angle acquisition section 92 does not execute subsequent processing and does not acquire the regulation position determination angle θi in the same calculation cycle. On the other hand, if the permission flag is set (step 102: YES), it is determined whether or not the signal indicating the vehicle speed SPD is normal (step 103). If the signal indicating the vehicle speed SPD is normal (step 103: YES), it is determined whether the vehicle speed SPD is greater than the low speed threshold value Slo (step 104). If the vehicle speed SPD is greater than the low speed threshold value Slo (step 104: YES), the subsequent processing is not executed and the restriction position determination angle θi is not acquired in the same calculation cycle. On the other hand, if the signal indicating the vehicle speed SPD is not normal (step 103: NO) and if the vehicle speed SPD is equal to or lower than the low speed threshold value Slo (step 104: NO), dynamic regulation determination is performed (step 105).

As shown in FIG. 7, in the dynamic restriction determination, the restriction position determination angle obtaining section 92 determines whether or not the steering torque Th is equal to or greater than the first steering torque threshold Tth1 (step 201). If the steering torque Th is greater than or equal to the first steering torque threshold Tth1 (step 201: YES), it is determined whether or not the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 (step 202). That is, at step 202, it is determined whether or not the sign of the motor angular velocity ωm is the same as the sign of the steering torque Th and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1. If the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 (step 202: YES), it is determined whether or not the angular velocity variation Δωm is less than the negative first angular velocity variation threshold Δωth1 (step 203). That is, at step 203, it is determined whether or not the sign of the angular velocity variation Δωm is opposite to the sign of the steering torque Th and the absolute value of the angular velocity variation Δωm is greater than the first angular velocity variation threshold Δωth1. When the angular velocity change amount Δωm is less than the negative first angular velocity change amount threshold value Δωth1 (step 203: YES), it is determined that the dynamic restriction determination is established and the movement of the rack shaft 12 is restricted. (Step 204).

On the other hand, if the steering torque Th is less than the first steering torque threshold Tth1 (step 201: NO), if the motor angular velocity ωm is equal to or less than the first angular velocity threshold ωth1 (step 202: NO), the angular velocity variation Δωm is negative If it is equal to or greater than the single angular velocity variation threshold value Δωth1 (step 203: NO), subsequent processing is not executed.

As shown in FIG. 6, after performing the dynamic restriction determination in step 105, the restriction position determination angle acquisition unit 92 determines whether or not the determination is established (step 106). When the dynamic restriction determination is established (step 106: YES), the count value Cdy of the dynamic counter indicating the number of times the dynamic restriction determination is established is incremented (step 107), and the number of times the static restriction determination is established. is cleared (step 108). Subsequently, it is determined whether or not the count value Cdy of the dynamic counter is equal to or greater than a predetermined count value Cth1 corresponding to the first predetermined time (step 109). (Step 109: NO), the subsequent processing is not executed.

On the other hand, when the count value Cdy is equal to or greater than the predetermined count value Cth1 (step 109: YES), the regulation position determination angle acquisition section 92 clears the count value Cdy of the dynamic counter (step 110). Then, the absolute steering angle θs obtained in the same calculation period is subjected to rigidity compensation to obtain the restriction position determination angle θi (step 111), and the acquisition of the restriction position determination angle θi is stopped until the ambient environment change determination is established. A stop flag is set (step 112).

When the dynamic restriction determination is not established (step 106: NO), the restriction position determination angle acquisition unit 92 performs static restriction determination (step 113).
As shown in FIG. 8, in the static restriction determination, the restriction position determination angle obtaining section 92 determines whether or not the steering torque Th is equal to or greater than the second steering torque threshold Tth2 (step 301). If the steering torque Th is equal to or greater than the second steering torque threshold Tth2 (step 301: YES), it is determined whether the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and equal to or less than the second angular velocity threshold ωth2. (step 302). That is, in step 302, it is determined whether or not the sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and is equal to or less than the second angular velocity threshold ωth2. determine whether When the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and equal to or less than the second angular velocity threshold ωth2, that is, when the motor 21 is rotating at an extremely low speed (step 302: YES), the angular velocity variation Δωm It is determined whether or not the absolute value is less than the second angular velocity variation threshold Δωth2 (step 303). Then, when the absolute value of the angular velocity change amount Δωm is less than the second angular velocity change amount threshold value Δωth2 (step 303: YES), the static restriction determination is established, and it is determined that the movement of the rack shaft 12 is restricted. (step 304).

On the other hand, if the steering torque Th is less than the second steering torque threshold Tth2 (step 301: NO), if the motor angular velocity ωm is equal to or less than the first angular velocity threshold ωth1 or greater than the second angular velocity threshold ωth2 (step 302: NO), and if the absolute value of the angular velocity variation Δωm is greater than or equal to the second angular velocity variation threshold Δωth2 (step 303: NO), the subsequent processing is not executed.

As shown in FIG. 6, after performing the static restriction determination in step 113, the restriction position determination angle obtaining section 92 determines whether or not the determination is established (step 114). If the static restriction determination is established (step 114: YES), the count value Cst of the static counter is incremented (step 115), and the count value Cdy of the dynamic counter is cleared (step 116). Subsequently, it is determined whether or not the count value Cst of the static counter is equal to or greater than a predetermined count value Cth2 corresponding to the second predetermined time (step 117), and if the count value Cst is less than the predetermined count value Cth2 (Step 117: NO), the subsequent processing is not executed.

On the other hand, when the count value Cst is equal to or greater than the predetermined count value Cth2 (step 117: YES), the regulation position determination angle acquisition section 92 clears the count value Cst of the static counter (step 118). Then, the absolute steering angle .theta.s obtained in the same calculation cycle is subjected to stiffness compensation to obtain the regulation position determination angle .theta.i (step 119), and the stop flag is set (step 120).

When the static restriction determination is not established (step 114: NO), that is, when the movement of the rack shaft 12 is not restricted, the restriction position determination angle acquisition unit 92 counts the dynamic counter and the static counter. The values Cdy and Cst are cleared (steps 121 and 122).

As shown in FIG. 9, when determining a change in the surrounding environment, the restriction position determination angle acquisition unit 92 acquires various state quantities (step 401), and determines whether or not the stop flag is set (step 402). If the stop flag is not set (step 402: NO), that is, if the regulation position determination angle θi has not been acquired and it is not necessary to determine whether the surrounding environment of the vehicle changes, then do not process.

On the other hand, when the stop flag is set (step 402: YES), the restriction position determination angle acquisition unit 92 calculates the steering amount θba (step 403), and the steering amount θba determines the steering return. It is determined whether or not it is greater than the threshold θth (step 404). When the return steering amount θba is greater than the return determination threshold value θth (step 404: YES), it is determined whether or not the signal indicating the vehicle speed SPD is normal (step 405). If the signal indicating the vehicle speed SPD is normal (step 405: YES), it is determined whether the vehicle speed SPD is equal to or higher than the travel threshold Smin (step 406). Then, when the vehicle speed SPD is equal to or higher than the running threshold Smin (step 406: YES), the permission flag is set (step 407) and the stop flag is reset (step 408).

If the vehicle speed SPD is not normal (step 405: NO), the regulation position determination angle acquisition unit 92 skips step 406 and proceeds to steps 407 and 408 to set the permission flag and reset the stop flag. Further, when the steering amount θba for steering back is equal to or less than the threshold θth for determining steering back (step 404: NO) and when the vehicle speed SPD is less than the running threshold Smin (step 406: NO), the permission flag is reset (step 409).

Next, the operation and effects of this embodiment will be described.
(1) For example, when the movement of the rack shaft 12 is restricted due to the steered wheels 4 coming into contact with a curbstone, the restriction position determination angle θi acquired at this time is the actual rack end angle, which is the actual end angle at which end contact actually occurs. It becomes an angle diverging from the angle. Therefore, if the end position corresponding angles θs_le and θs_re on the corresponding side are set based on only the single regulation position determination angle θi, the end position corresponding angles θs_le and θs_re are likely to deviate from the actual rack end angle. Therefore, it is conceivable to set the end position correspondence angles θs_le and θs_re on the corresponding side based on a plurality of regulation position determination angles θi on either one of the left side and the right side. As a result, for example, even if one of the plurality of regulation position determination angles θi is obtained when hitting a curbstone, if the other regulation position determination angles θi are obtained when hitting the end, the set end position It is possible to prevent the corresponding angles θs_le and θs_re from deviating from the actual rack end angle. However, for example, when a plurality of regulation position determination angles θi are obtained when hitting a curbstone, the end position corresponding to the left or right side of the regulation position judgment angles θi is determined. Even if the angles θs_le and θs_re are set, there is a possibility that the end position corresponding angles θs_le and θs_re deviate from the actual rack end angles.

In this respect, the restriction position determination angle acquisition unit 92 acquires another restriction position determination angle θi after the surrounding environment of the vehicle changes after setting one restriction position determination angle θi. Therefore, it is possible to prevent any of the plurality of restriction position determination angles θi from becoming data acquired when the movement of the rack shaft 12 is restricted due to hitting a curb or the like. As a result, the end position correspondence angles θs_le and θs_re that accurately correspond to the actual rack end angles can be set.

(2) Since the conditions under which the surrounding environment change determination is satisfied include that the steering amount θba for steering return is equal to or greater than the threshold value θth for steering return determination and that the vehicle speed SPD is equal to or greater than the running threshold Smin, the surrounding environment is preferably It can be determined whether or not has changed.

(3) Regardless of whether or not the signal indicating the vehicle speed SPD input from the vehicle speed sensor 31 is normal, the regulation position determination angle acquisition unit 92 detects the rack shaft 12 when the vehicle speed SPD is equal to or lower than the low speed threshold value Slo. is restricted. Therefore, even if there is an abnormality in the signal indicating the vehicle speed SPD, the regulation position determination angle θi can be obtained, so the end position correspondence angles θs_le and θs_re can be set early. In addition, when the signal indicating the vehicle speed SPD is abnormal, the regulation position determination angle obtaining unit 92 does not include the magnitude comparison between the vehicle speed SPD and the running threshold Smin in the determination of the change in the surrounding environment. It is possible to prevent the surrounding environment change determination from becoming unsatisfactory due to an abnormality.

(4) The restriction position determination angle acquisition unit 92 performs dynamic restriction determination, and determines that movement of the rack shaft 12 is restricted when the dynamic restriction determination is established. The conditions under which the dynamic regulation determination is established are that the absolute value of the steering torque Th is equal to or greater than the first steering torque threshold value Tth1, and that the sign of the angular velocity change amount Δωm is opposite to the sign of the steering torque Th and that the angular velocity The absolute value of the variation Δωm is larger than the first angular velocity variation threshold Δωth1.

Here, for example, when the rack shaft 12 is quickly moved to the right by the driver's steering, and the motor 21 is rapidly rotating and the end hits the motor 21, the motor 21 is about to stop suddenly. Therefore, when the movement of the rack shaft 12 is restricted in this manner, for example, when a positive steering torque Th equal to or greater than the first steering torque threshold value Tth1 is input, the angular velocity change amount Δωm of the motor 21 becomes negative. It is less than one angular velocity variation threshold value Δωth1. In other words, when momentary end contact occurs, the dynamic restriction determination can be established. Therefore, in the present embodiment, for example, when the steering is quickly turned and the end hits instantaneously, it can be determined that the movement of the rack shaft 12 is restricted. θs_re can be set.

(5) As described above, for example, the rack shaft 12 is moved to the right by the driver's steering, and the motor 21 does not move the rack shaft 12 until the motor 21 suddenly stops after momentary end contact occurs. Rotate in the direction that moves it to the right. Therefore, as in the present embodiment, the condition for establishing the dynamic restriction determination includes that the motor angular velocity ωm is larger than the first angular velocity threshold ωth1 having the same sign as the steering torque Th, thereby achieving instantaneous end contact. It is possible to accurately determine whether or not there has occurred.

(6) The restriction position determination angle acquisition unit 92 performs static restriction determination, and determines that movement of the rack shaft 12 is restricted when the static restriction determination is established. The conditions for static regulation determination are that the absolute value of the steering torque Th is equal to or greater than a second steering torque threshold Tth2, which is larger than the first steering torque threshold Tth1, and that the absolute value of the angular velocity change amount Δωm is equal to or greater than the first angular velocity It includes being equal to or less than a second angular velocity variation threshold Δωth2 which is smaller than the variation threshold Δωth1.

Here, for example, when the rack shaft 12 moves to the right due to steering by the driver and the end hits, the motor 21 hardly rotates even if the turning steering is continued. Therefore, when the movement of the rack shaft 12 is restricted in this manner, the absolute value of the angular velocity change amount Δωm of the motor 21 becomes the second It is equal to or less than the two angular velocity variation threshold Δωth2. That is, if the steering is performed so as to maintain the steering after the end hit occurs, the static regulation determination can be established. Therefore, in the present embodiment, for example, when the steering is carried out so as to maintain the steering after the end hit occurs, it can be determined that the movement of the rack shaft 12 is restricted, and the restriction position determination angle θi is acquired to correspond to the end position. Angles θs_le and θs_re can be set.

(7) Strictly speaking, the motor 21 slightly rotates due to the elastic deformation of the EPS 2 when the turning steering is continued even after the end hit occurs as described above. Therefore, as in the above configuration, the condition for establishing the static restriction determination is that the motor angular velocity ωm is larger than the first angular velocity threshold ωth1 having the same sign as the steering torque Th and is equal to or smaller than the second angular velocity threshold ωth2. By including this, it is possible to accurately determine whether or not continuous end contact has occurred.

(8) The restriction position determination angle acquisition unit 92 performs dynamic restriction determination and static restriction determination. is determined to be regulated. Therefore, when the movement of the rack shaft 12 is restricted in various ways, the restricted position determination angle θi can be obtained, and the end position corresponding angles θs_le and θs_re can be set early.

Here, for example, it is assumed that the turning steering is performed quickly, and after the steered wheels 4 hit the curb or the like and the movement of the rack shaft 12 is restricted, the turning steering is continued. In this case, both the dynamic restriction determination and the static restriction determination can be established. Therefore, assuming that the restriction position determination angle θi is obtained when each determination is satisfied, which of the two restriction position determination angles θi This is the data when the movement of the rack shaft 12 is restricted due to the same curb. Therefore, in the configuration for performing dynamic restriction determination and static restriction determination, after one restriction position determination angle θi is set as in the present embodiment, another restriction position determination is performed after the surrounding environment of the vehicle changes. The effect of obtaining the angle θi is great.

(9) The restriction position determination angle acquisition unit 92 determines the mechanical mechanical A value obtained by performing rigidity compensation based on the elastic deformation is acquired as the restriction position determination angle θi. Therefore, it is possible to obtain an accurate restriction position determination angle θi in consideration of the elastic deformation of the EPS 2 when it is determined that the movement of the rack shaft 12 is restricted.

(10) The regulation position determination angle acquisition unit 92 calculates the pinion shaft torque Tp based on the steering torque Th, the motor torque, and the inertia torque. A deformation amount can be calculated accurately, and a more accurate restriction position determination angle θi can be set. Especially in the dynamic restriction determination, the sudden stop of the motor 21 increases the inertia torque, so the effect is great.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
In the above embodiment, it may be determined whether the movement of the rack shaft 12 is restricted even when the signal indicating the vehicle speed SPD is normal and the vehicle speed SPD is greater than the low speed threshold value Slo. Further, when the signal indicating the vehicle speed SPD input from the vehicle speed sensor 31 is abnormal, it is not necessary to determine whether the movement of the rack shaft 12 is restricted.

- In the above-described embodiment, even when the signal indicating the vehicle speed SPD is abnormal, the determination of a change in the surrounding environment may include a comparison between the vehicle speed SPD and the running threshold Smin.
In the above embodiment, the restriction position determination angle acquisition unit 92 performs dynamic restriction determination and static restriction determination to determine whether or not the movement of the rack shaft 12 is restricted. It may be determined whether or not the movement of the rack shaft 12 is restricted by performing either one of the dynamic restriction determination and the static restriction determination.

In the above embodiment, the above (c1) and (c2) are satisfied as the conditions for determining a change in the surrounding environment, but the present invention is not limited to this. The condition c1) may not be determined. Further, for example, in addition to or in place of the above condition (c2), the surroundings of the vehicle may be photographed by a photographing device such as a camera, and whether or not the photographed image has changed may be included. Further, for example, positioning signals from artificial satellites for GPS (Global Positioning System) may be received, and based on the received positioning signals, it may be determined whether or not the position of the vehicle has changed by a predetermined distance or more. Furthermore, it may be determined that the surrounding environment of the vehicle has changed after a period of time of, for example, several minutes has elapsed, and the determination conditions for determining a change in the surrounding environment can be changed as appropriate.

- In the above embodiment, if the above (a1) and (a3) are established, it may be determined that the dynamic restriction determination is established even if (a2) is not established. Further, the restriction position determination angle θi may be acquired if the dynamic restriction determination is satisfied even for one calculation cycle, regardless of whether or not the dynamic restriction determination is satisfied continuously for the first predetermined time.

- In the above embodiment, if the above (b1) and (b3) are established, it may be determined that the static regulation determination is established even if (b2) is not established. Alternatively, the restriction position determination angle θi may be acquired if the static restriction determination is satisfied even for one calculation cycle, regardless of whether the static restriction determination is satisfied continuously for the second predetermined time.

・In the above embodiment, the pinion shaft torque Tp is calculated based on the steering torque Th, the motor torque and the inertia torque. may be used to calculate the pinion shaft torque Tp. Also, as a result of the dynamic regulation determination, the pinion shaft torque Tp used for stiffness compensation for the acquired absolute steering angle θs, and as a result of the static restriction determination, used for stiffness compensation for the acquired absolute steering angle θs It may differ from the pinion shaft torque Tp.

- In the above-described embodiment, the absolute steering angle θs obtained when it is determined that the movement of the rack shaft 12 is restricted may be obtained as it is as the restricted position determination angle θi, and rigidity compensation may not be performed.

- In the above embodiment, when a plurality of regulation position determination angles θi on only one of the left side and the right side are obtained, the average value of these is set as the end position corresponding angles θs_le and θs_re on the corresponding side. However, the present invention is not limited to this, and for example, the restriction position determination angle θi having the largest absolute angle among the plurality of restriction position determination angles θi may be set as the end position corresponding angles θs_le and θs_re on the corresponding side.

In the above embodiment, by monitoring whether or not the motor 21 is rotating even when the ignition switch is turned off, the number of revolutions of the motor 21 from the origin is constantly integrated, and the absolute motor angle and the absolute steering angle θs are detected. However, the present invention is not limited to this. For example, a steering sensor that detects the steering angle as an absolute angle is provided, and the number of revolutions of the motor 21 from the origin is calculated based on the steering angle detected by the steering sensor and the speed reduction ratio of the speed reduction mechanism 22. The motor absolute angle and the absolute steering angle θs may be detected by integration.

In the above embodiment, the end contact mitigation control is executed by limiting the assist command value Ias* to the steering angle limit value Ien. The end contact mitigation control may be executed by adding a steering reaction force component that increases as it approaches, that is, a component having the opposite sign to the assist command value Ias*.

In the above embodiment, guard processing is performed on the assist command value Ias*, but this is not limitative. may be guarded.

In the above embodiment, the limit value setting unit 62 includes the voltage limit value calculator 72 that calculates the voltage limit value Ivb based on the power supply voltage Vb. Alternatively or alternatively, another computing unit that computes other limit values based on other state quantities may be provided. Alternatively, the limit value setting unit 62 may not include the voltage limit value calculation unit 72, and the steering angle limit value Ien may be set directly as the limit value Ig.

In the above embodiment, the steering angle limit value Ien is obtained by subtracting the angle limit component Iga from the rated current Ir. A value obtained by subtracting the limit amount may be used as the steering angle limit value Ien.

In the above embodiment, the steering control device 1 controls the EPS 2 in which the EPS actuator 6 applies the motor torque to the column shaft 15. However, the steering control device 1 is not limited to this. The control object may be a steering device that applies a motor torque to the . Further, not limited to the EPS, the steering control device 1 controls a steer-by-wire type steering device in which power transmission between a steering unit operated by a driver and a steering unit for steering the steered wheels is separated. As a target, the torque command value or the q-axis current command value of the motor of the steering actuator provided in the steering portion may be subjected to the end contact mitigation control as in the present embodiment.

DESCRIPTION OF SYMBOLS 1... Steering control apparatus 2... Electric power steering apparatus 4... Steering wheel 6... EPS actuator 11... Steering shaft 12... Rack shaft 13... Rack housing 18... Rack end 21... Motor 31... Vehicle speed Sensor 41 Microcomputer 53 Absolute steering angle detection unit 65 End position corresponding angle management unit 92 Regulation position determination angle acquisition unit 93 End position corresponding angle setting unit SPD Vehicle speed Slo Low speed threshold value Smin... Traveling threshold Th... Steering torque Tth1... First steering torque threshold Tth2... Second steering torque threshold ?m... Rotational angle ?s... Absolute steering angle ?i... Regulation position determination angle ?s_le, ?s_re... End position Corresponding angles, θba: steering amount for steering back, θth: threshold for determination of steering back, ωm: motor angular velocity, ωth1: first angular velocity threshold, ωth2: second angular velocity threshold, Δωm: angular velocity change amount, Δωth1: first angular velocity change amount threshold , Δωth2 . . . second angular velocity variation threshold.

Claims (3)

A steering device comprising a housing, a steered shaft reciprocatingly housed in the housing, and an actuator for applying motor torque for reciprocating the steered shaft using a motor as a drive source is controlled,
An absolute steering angle detection unit that detects an absolute steering angle that is a rotation angle of a rotating shaft that can be converted into a steering angle of a steered wheel that is connected to the steering shaft and that is expressed as an absolute angle including a range exceeding 360°. and,
It is determined whether or not the movement of the steering shaft to one of the left and right sides is restricted, and the restricted position determination angle corresponds to the absolute steering angle when it is determined that the movement of the steering shaft is restricted. a regulation position determination angle acquisition unit that acquires
An end position for setting an end position corresponding angle corresponding to the absolute steering angle, which is an angle indicating that the steering shaft is at the left or right end position based on the plurality of the regulation position determination angles. and a corresponding angle setting unit,
The regulation position determination angle acquisition unit acquires the one regulation position determination angle until a surrounding environment change determination is established as to whether or not the surrounding environment of the vehicle has changed. is the one that does not get the
The condition for establishing the surrounding environment change determination includes that the vehicle speed is equal to or higher than a running threshold value indicating a non-stop state of the vehicle,
The regulation position determination angle acquisition unit includes:
Regardless of whether the signal indicating the vehicle speed input from the vehicle speed sensor is normal or not, the movement of the steering shaft is restricted when the vehicle speed is equal to or lower than the low speed threshold indicating that the vehicle is running at a low speed. It determines whether or not there is
A steering control device wherein the condition for establishing the determination of a change in the surrounding environment does not include that the vehicle speed is greater than the running threshold when the signal indicating the vehicle speed is abnormal. The steering control device according to claim 1, wherein
The steering control device, wherein the condition for establishing the surrounding environment change determination includes that the return steering amount is greater than or equal to the return determination threshold value. The steering control device according to claim 1 or 2 ,
The restriction position determination angle acquisition unit performs dynamic restriction determination and static restriction determination, and when either one of the dynamic restriction determination and the static restriction determination is established, the movement of the steering shaft is determined. is determined to be regulated,
The sign of the steering torque that moves the steering shaft in one direction and the sign of the rotation direction of the motor are positive, and the sign of the steering torque that moves the steering shaft in the direction opposite to the one direction and the rotation of the motor. When the sign of each direction is negative,
The conditions under which the dynamic restriction determination is established include that the absolute value of the steering torque is equal to or greater than a first steering torque threshold, and that the sign of the angular velocity change amount, which is the amount of change in the angular velocity of the motor, is the sign of the steering torque. Contrary to, including that the absolute value of the angular velocity variation is greater than the first angular velocity variation threshold,
The conditions under which the static regulation determination is established include that the absolute value of the steering torque is equal to or greater than a second steering torque threshold that is larger than the first steering torque threshold, and that the absolute value of the angular velocity change amount is equal to or greater than the first steering torque threshold. A steering control device including being equal to or less than a second angular velocity variation threshold that is smaller than the angular velocity variation threshold.

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