JP2021049940A - Steering control device - Google Patents

Abstract

To provide a steering control device capable of learning an end position corresponding angle which accurately corresponds to an actual end angle.SOLUTION: An end position corresponding angle management unit 65 includes a limit position determination angle acquisition unit 92 for determining whether the movement of a rack shaft to one of left and right sides is limited, and for acquiring a limit position determination angle θi corresponding to an absolute steering angle when determining that the movement of the rack shaft is limited. In addition, the end position corresponding angle management unit 65 includes an end position corresponding angle setting unit 93 for setting end position corresponding angles θs_le and θs_re on the basis of the plurality of limit position determination angles θi. After acquiring one limit position determination angle θi, the limit position determination angle acquisition unit 92 does not acquire another limit position determination angle θi until surrounding environment change determination on whether a surrounding environment around a vehicle has changed is established.SELECTED DRAWING: Figure 4

Description

The present invention relates to a steering control device.

Conventionally, as a vehicle steering device, an electric power steering device (EPS) including an actuator whose drive source is a motor is known. Some such EPS acquire the steering angle of the steering wheel as an absolute angle including a range exceeding 360 °, and perform various controls based on the steering angle. As an example of such control, for example, Patent Document 1 discloses a device that executes end contact relaxation control for alleviating 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 axis is physically restricted by the end contact is associated with the steering angle, and the same angle is stored as the end position corresponding angle. Then, in the EPS, the impact of the end contact is mitigated by reducing the target value of the motor torque output by the motor according to the distance from the end position corresponding angle of the steering angle.

Japanese Unexamined Patent Publication No. 2016-155519

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

An object of the present invention is to provide a steering control device capable of learning an end position corresponding angle that corresponds accurately to an actual end angle.

The steering control device that solves the above problems includes a housing, a steering shaft that is reciprocally housed in the housing, and an actuator that applies motor torque that reciprocates the steering shaft using a motor as a drive source. An absolute steering angle represented by an absolute angle including a range exceeding 360 °, which is a rotation angle of a rotation shaft that can be converted into a steering angle of a steering wheel connected to the steering shaft, with a steering device provided as a control target. The absolute steering angle detection unit that detects the above, and the above-mentioned when it is determined whether or not the movement of the steering shaft to the left or right is restricted, and it is determined that the movement of the steering shaft is restricted. An angle indicating that the steering axis is at the end position based on the regulated position determination angle acquisition unit that acquires the regulated position determination angle according to the absolute steering angle and the plurality of the regulated position determination angles. The end position corresponding angle setting unit for setting the end position corresponding angle associated with the absolute steering angle is provided, and the regulated position determination angle acquisition unit acquires one of the regulated position determination angles and then surrounds the vehicle. Until the determination of the change in the surrounding environment as to whether or not the environment has changed is established, the other restricted position determination angle is not acquired.

Here, for example, when the movement of the steering shaft is restricted by the steering wheel hitting the curb, the regulated position determination angle acquired at this time is an angle deviating from the actual end angle. Therefore, if the end position corresponding angle is set based on only a single regulated 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 corresponding angle based on a plurality of regulated position determination angles. As a result, for example, even if one of the plurality of regulated position determination angles is acquired at the time of curb hitting, if the other regulated position determination angles are acquired at the time of end hitting, the end position corresponding angle is the actual end. It is possible to suppress the angle deviating from the angle. However, for example, when a plurality of end position corresponding angles are acquired at the time of curb hitting, even if the end position corresponding angles are set based on a plurality of regulated position determination angles, the end position corresponding angles are the actual ends. The angle may deviate from the angle.

In this respect, according to the above configuration, the other regulated position determination angle is acquired after the surrounding environment of the vehicle changes after setting one regulated position determination angle. Therefore, it is possible to prevent any of the plurality of regulated position determination angles from becoming data acquired when the movement of the steering shaft is regulated by hitting a curb or the like. As a result, it is possible to set an end position corresponding angle that accurately corresponds to the actual end angle.

In the steering control device, it is preferable that the condition for establishing the peripheral environment change determination includes that the turning back steering amount is equal to or larger than the turning back determination threshold value.
According to the above configuration, since the condition for determining the change in the surrounding environment includes the turning back steering, it is possible to preferably determine whether or not the surrounding environment has changed.

In the steering control device, it is preferable that the condition for establishing the peripheral environment change determination includes that the vehicle speed is equal to or higher than the traveling threshold value indicating the non-stop state of the vehicle.
According to the above configuration, since the condition for establishing the surrounding environment change determination includes the traveling of the vehicle, it is possible to preferably determine whether or not the surrounding environment has changed.

In the steering control device, the regulated position determination angle acquisition unit has the vehicle speed equal to or lower than the low speed threshold value indicating the low speed running of the vehicle regardless of whether or not the signal indicating the vehicle speed input from the vehicle speed sensor is normal. In the case of, it is determined whether or not the movement of the steering shaft is restricted, and when the signal indicating the vehicle speed is abnormal, the condition for establishing the peripheral environment change determination is satisfied. It is preferable not to include that the vehicle speed is larger than the traveling threshold value.

According to the above configuration, even if an abnormality occurs in the signal indicating the vehicle speed input from the vehicle speed sensor, the regulated position determination angle can be acquired, so that the end position corresponding angle can be set at an early stage. In addition, when the signal indicating the vehicle speed is abnormal, the judgment of the change in the surrounding environment is not established due to the abnormality of the signal indicating the vehicle speed because the magnitude comparison between the vehicle speed and the traveling threshold value is not included in the judgment of the change in the surrounding environment. Can be prevented.

In the steering control device, the regulated position determination angle acquisition unit makes a dynamic regulation determination and a static regulation determination, and when either the dynamic regulation determination or the static regulation determination is established, the 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 code of the rotation direction of the motor are positive and opposite to the one direction, respectively. 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 absolute value of the steering torque is the first steering under the condition that the dynamic regulation determination is established. It is equal to or greater than the torque threshold, and the sign of the angular speed change amount, which is the amount of change in the angular speed of the motor, is opposite to the sign of the steering torque, and the absolute value of the angular speed change amount is larger than the first angular speed change amount 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 the second steering torque threshold larger than the first steering torque threshold, and the absolute amount of change in angular velocity is absolute. It is preferable that the value is equal to or less than the second angular velocity change amount threshold, which is smaller than the first angular velocity change amount threshold.

According to the above configuration, when the movement of the steering shaft is restricted in various modes, the regulated position determination angle can be acquired, and the end position corresponding angle can be set at an early stage. Here, for example, it is assumed that the turning steering is performed quickly, and after the steering wheel hits a curb or the like and the movement of the steering shaft is restricted, the turning steering is continuously performed as it is. In this case, since each of the dynamic regulation determination and the static regulation determination can be established, if the regulation position determination angle is acquired when each determination is established, both of the two regulation position determination angles are the same. It is the data when the movement of the steering shaft is regulated by hitting the curb. Therefore, in the configuration in which each judgment of the dynamic regulation judgment and the static regulation judgment is performed, after setting one regulation position judgment angle as in the above configuration, the other regulation position judgment angle is set after the surrounding environment of the vehicle changes. The effect to acquire is great.

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

Schematic diagram of the electric power steering device. Block diagram of the steering control device. Block diagram of the limit value setting section. Block diagram of the end position corresponding angle management unit. The schematic diagram which shows the relationship between the absolute rudder angle and the pinion shaft torque. The flowchart which shows the processing procedure which concerns on the acquisition of the regulation position determination angle by the regulation position determination angle acquisition part. The flowchart which shows the processing procedure of the dynamic regulation determination by the regulation position determination angle acquisition part. The flowchart which shows the processing procedure of the static regulation judgment by the regulation position judgment angle acquisition part. The flowchart which shows the processing procedure of the surrounding environment change judgment by the regulation position judgment angle acquisition part.

Hereinafter, an embodiment of the steering control device will be described with reference to the drawings.
As shown in FIG. 1, the electric power steering device (EPS) 2 as a steering device to be controlled by the steering control device 1 is a steering mechanism that steers the steering wheel 4 based on the operation of the steering wheel 3 by the driver. It has 5. Further, the EPS 2 includes an EPS actuator 6 as an actuator that applies an assist force for assisting the steering operation to the steering mechanism 5.

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. A rack and pinion mechanism 14 that converts the rotation of the steering shaft 11 into a rack shaft 12 is provided. The steering shaft 11 is configured by connecting the column shaft 15, the intermediate shaft 16, and the 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 at a predetermined crossing angle. The rack and pinion mechanism 14 is configured such that the rack teeth 12a formed on the rack shaft 12 and the pinion teeth 17a formed on the pinion shaft 17 are meshed with each other. Further, tie rods 19 are rotatably connected to both ends of the rack shaft 12 via rack ends 18 formed of ball joints provided at the shaft end portions. The tip of the tie rod 19 is connected to a knuckle (not shown) to which the steering wheel 4 is assembled. Therefore, in EPS2, the rotation of the steering shaft 11 accompanying the steering operation is converted into the axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckle via the tie rod 19. The steering angle of the steering wheel 4, that is, the traveling direction of the vehicle is changed.

The position of the rack shaft 12 in which the rack end 18 abuts on the left end of the rack housing 13 is a position where the maximum steering is possible in the right direction, and the same position corresponds to the rack end position as the right end position. Further, the position of the rack shaft 12 in which the rack end 18 abuts on the right end of the rack housing 13 is a position where the maximum steering is possible in the left direction, and the same 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 reduction mechanism 22 such as a worm and wheel. The motor 21 is connected to the column shaft 15 via the reduction mechanism 22. Then, the EPS actuator 6 decelerates the rotation of the motor 21 by the reduction 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 used for the motor 21 of the present embodiment.

The steering control device 1 is connected to the 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 that detects the vehicle speed SPD of the vehicle and a torque sensor 32 that detects the steering torque Th applied to the steering shaft 11 by the driver's steering. Further, the steering control device 1 is connected to a rotation sensor 33 that detects the rotation angle θm of the motor 21 at a relative angle within a range of 360 °. The steering torque Th and the rotation angle θm are detected as positive values when the vehicle is steered to the right and negative values when the vehicle is steered to the left, for example. That is, in the present embodiment, the sign of the steering torque Th for moving the rack shaft 12 to the right corresponding to one direction and the sign of the rotation direction of the motor 21 are positive, respectively, and the left direction corresponding to the opposite direction to one direction. The sign of the steering torque Th that moves the rack shaft 12 and the sign of the rotation direction of the motor 21 are negative. Then, the steering control device 1 supplies driving power to the motor 21 based on the signals indicating each state quantity input from each of these sensors, thereby operating the EPS actuator 6, that is, the rack shaft 12 to the steering mechanism 5. Controls the assist force applied to reciprocate.

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. The drive circuit 42 of the present embodiment employs a well-known PWM inverter having a plurality of switching elements such as FETs. The motor control signal Sm output by 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 for the motor coil of each phase is switched, so that the DC power of the vehicle-mounted power supply 43 is converted into the three-phase drive power of the motor 21. Is output to.

Each control block shown below is realized by a computer program executed by the microcomputer 41, detects each state quantity in a predetermined sampling cycle, and is shown in each of the following control blocks at a predetermined calculation cycle. Each arithmetic processing is executed.

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

Specifically, the microcomputer 41 has a current command value calculation unit 51 that calculates current command values Id * and Iq *, and a motor control signal generation unit 52 that outputs a motor control signal Sm based on the current command values Id * and Iq *. And an absolute steering angle detecting unit 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 calculation unit 51. The current command value calculation unit 51 calculates the current command values Id * and Iq * based on these state quantities. The current command values Id * and Iq * are target values of the current to be supplied to the motor 21, and indicate the current command value on the d-axis and the current command value on the 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 output by the motor 21. In this embodiment, the d-axis current command value Id * is basically fixed to zero. The current command values Id * and Iq * are, for example, positive values when assisting steering to the right and negative values when assisting steering to the left.

The current command values Id *, Iq *, each phase current value Iu, Iv, Iw, and the rotation angle θm of the motor 21 are input to the motor control signal generation unit 52. The motor control signal generation unit 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 generation unit 52 maps the current values Iu, Iv, and Iw of each phase on the d / q coordinates based on the rotation angle θm, so that the actual motor 21 in the d / q coordinate system is actually generated. The d-axis current value Id and the q-axis current value Iq, which are the current values, are calculated. Then, the motor control signal generation unit 52 causes 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 *. The motor control signal Sm is generated by performing the control. The q-axis current value Iq calculated in the process of generating the motor control signal Sm is output to the current command value calculation unit 51.

The motor control signal generation unit 52 outputs the motor control signal Sm thus generated to the drive circuit 42. As a result, the driving power corresponding to the motor control signal Sm is supplied to the motor 21, and the motor torque corresponding to the q-axis current command value Iq * is output from the motor 21, so that the steering mechanism 5 is assisted. Granted.

The rotation angle θm is input to the absolute steering angle detection unit 53. The absolute steering angle detection unit 53 detects the absolute motor angle represented by the absolute angle including the range exceeding 360 ° based on the rotation angle θm. The absolute steering angle detection unit 53 of the present embodiment integrates the rotation speed 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 replacing the in-vehicle power supply 43, and integrates the rotation speed. The absolute angle of the motor is detected based on the number and the angle of rotation θm. Then, the absolute steering angle detection unit 53 detects the absolute steering angle θs indicating the steering angle of the steering shaft 11 by multiplying the absolute steering angle of the motor by a conversion coefficient based on the reduction ratio of the reduction mechanism 22. 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 rotation speed of the motor 21 is constantly integrated. As a result, 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, even when the start switch is turned on for the second time or later after the vehicle power supply 43 is replaced.

Since the steering angle of the steering wheel 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 rotation shaft that can be converted into the steering angle of the steering wheel 4. .. Further, the absolute motor angle and the absolute steering angle θs are, for example, positive values when the rotation angle is in the right direction from the origin, and negative values when the rotation angle is in the left direction.

Next, the configuration of the current command value calculation unit 51 will be described in detail.
The current command value calculation unit 51 is an upper limit of the absolute value of the assist command value calculation unit 61 that calculates the assist command value Ias *, which is the basic component of the q-axis current command value Iq *, and the q-axis current command value Iq *. It includes 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. Further, the current command value calculation unit 51 includes an end position correspondence angle management unit 65 that manages end position correspondence angles θs_le and θs_re, which are 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 calculation unit 61. The assist command value calculation unit 61 calculates the 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 the vehicle speed SPD becomes slower. The assist command value Ias * calculated in this way is output to the guard processing unit 63.

In addition to the assist command value Ias *, the limit value Ig set in the limit value setting unit 62 is input to the guard processing unit 63 as will be described later. 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 sets the value of the assist command value Ias * as it is as the q-axis current command value Iq * and sets the motor control signal generation 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 value obtained by limiting the absolute value of the assist command value Ias * to the value of the limit value Ig is the q-axis current command value Iq *. Is output to the motor control signal generation unit 52.

The memory 64 stores the rated current Ir as the maximum current corresponding to the torque preset as the motor torque that can be output by the motor 21, 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. The memory 64 of the present embodiment is of a type that holds the end position corresponding angles θs_le and θs_re unless, for example, the in-vehicle power supply 43 is removed.

Next, the configuration of the limit value setting unit 62 will be described.
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 other limit values based on the power supply voltage Vb. It is provided with a voltage limit value calculation unit 72 for calculating the voltage limit value Ivb of the above, and a minimum value selection unit 73 for selecting whichever of the steering angle limit value Ien and the voltage limit value Ivb is smaller.

Absolute steering angle θs, vehicle speed SPD, rated current Ir, and end position corresponding angles θs_le and θs_re are input to the steering angle limit value calculation unit 71. Based on these state quantities, the rudder angle limit value calculation unit 71 has an 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 rudder angle θs as a predetermined angle θ1 or less, as will be described later. In the case of, the steering angle limit value Ien that becomes smaller is calculated based on the decrease of the end separation angle Δθ. The steering angle limit value Ien calculated in this way is output to the minimum value selection unit 73. The steering angle limit value calculation unit 71 does not calculate the steering angle limit value Ien when neither the left and right end position corresponding angles θs_le and θs_re are set in the memory 64.

The power supply voltage Vb is input to the voltage limit value calculation unit 72. The voltage limit value calculation unit 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 the preset voltage threshold Vth. Specifically, when the absolute value of the power supply voltage Vb becomes equal to or less than the voltage threshold Vth, the voltage limit value calculation unit 72 has a voltage limit value having a smaller absolute value based on the decrease in the absolute value of the power supply voltage Vb. Calculate Ivb. The voltage limit value Ivb calculated in this way is output to the minimum value selection unit 73.

The minimum value selection unit 73 selects the smaller of the input steering angle limit value Ien and the voltage limit value Ivb as the limit value Ig, and outputs the limit value Ig to the guard processing unit 63.
Then, the steering angle limit value Ien is output as the limit value Ig to the guard processing unit 63, so that the absolute value of the q-axis current command value Iq * is limited to the steering angle limit value Ien. As a result, when the end separation angle Δθ is equal to or less than the predetermined angle θ1, the rack end 18 becomes the rack housing 13 by reducing the absolute value of the q-axis current command value Iq * based on the decrease in the end separation angle Δθ. The end contact mitigation control that alleviates the impact of the end contact that hits is executed. 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, the normal end guess 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. When it is memorized, it becomes a provisional end guess relaxation control.

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

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

Specifically, the absolute steering angle θs and the end position corresponding angles θs_le and θs_re are input to the end separation angle calculation unit 81. 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 calculation unit 81 sets the absolute steering angle θs in the latest calculation cycle and the left end position corresponding angle θs_le. The difference between them and the difference between the absolute steering angle θs in the latest calculation cycle and the right end position corresponding angle θs_re are calculated. Then, the end separation angle calculation unit 81 outputs the smaller absolute value of the calculated differences to the angle limiting component calculation unit 82 as the end separation angle Δθ. On the other hand, the end separation angle calculation unit 81 stores the absolute steering angle θs and the end position correspondence angle in the latest calculation cycle when only one of the left and right end position correspondence angles θs_le and θs_re is stored in the memory 64. Calculate the difference between θs_le or the end position correspondence angle θs_re. Then, the end separation angle calculation unit 81 outputs this difference as the end separation angle Δθ to the angle limiting component calculation unit 82.

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

The end separation angle Δθ and the vehicle speed SPD are input to the angle limiting component calculation unit 82. The angle limiting component calculation unit 82 includes a map that defines the relationship between the end separation angle Δθ and the vehicle speed SPD and the angle limiting component Iga, and by referring to the map, the angle according to the end separation angle Δθ and the vehicle speed SPD. Calculate the limiting component Iga.

In this map, the angle limiting component Iga decreases in proportion to the increase from the state where the end separation angle Δθ is zero, the end separation angle Δθ reaches zero at a predetermined angle θ1, and the end separation angle Δθ is from the predetermined angle θ1. Is set to zero as it grows. In this map, a region where the end separation angle Δθ is negative is also set, and the angle limiting component Iga increases in proportion to the decrease when the end separation angle Δθ becomes smaller than zero, and becomes the rated current Ir. After reaching the same value, it becomes constant. The negative region in the map assumes that the EPS 2 is elastically deformed and the motor 21 is rotated by further cutting and steering from the state where the rack end 18 is in contact with the rack housing 13. The predetermined angle θ1 is set to a small angle indicating a range in the vicinity of the end position corresponding angles θs_le and θs_re. That is, the angle limiting component Iga becomes smaller as the absolute steering angle θs decreases from the end position corresponding angles θs_le and θs_re toward the steering neutral side, and when the absolute steering angle θs is closer to the steering neutral position than near the end position corresponding angles θs_le and θs_re, It is set to zero.

Further, this map is set so that the angle limiting component Iga becomes smaller in the region where the end separation angle Δθ is equal to or less than the predetermined angle θ1 based on the increase in the vehicle speed SPD. Specifically, the angle limiting component Iga is set to be larger than zero when the vehicle speed SPD is in the low speed range, but the angle limiting component Iga is set to be zero when the vehicle speed SPD is in the medium and high speed range. .. The angle limiting component Iga calculated in this way is output to the subtractor 83.

In addition to the angle limiting component Iga, the rated current Ir is input to the subtractor 83. The steering angle limit value calculation unit 71 outputs to the minimum value selection unit 73 the value obtained by subtracting the angle limiting component Iga from the rated current Ir in the subtractor 83 as the steering angle limiting value Ien.

Next, the configuration of the end position corresponding angle management unit 65 will be described.
As shown in FIG. 2, the end position corresponding angle management unit 65 is input with 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. Will be done. The end position corresponding angle management unit 65 determines whether or not the movement of the rack shaft 12 to the left or right is restricted based on these state quantities, and determines that the movement of the rack shaft 12 is restricted. Acquire a plurality of regulated position determination angles θi according to the absolute steering angle θs at the time of determination. Then, the end position corresponding angle management unit 65 stores the end position corresponding angles θs_le and θs_re in the memory 64 based on the plurality of regulated position determination angles θi. After the end position corresponding angles θs_le and θs_re are temporarily stored in the memory 64, the end position corresponding angle management unit 65 does not execute the process related to the setting of the end position corresponding angles θs_le and θs_re until they 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 regulated 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 change amount calculation unit 91. The angular velocity change amount calculation unit 91 calculates the 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 unit 91 outputs the angular velocity change amount Δωm to the regulation position determination angle acquisition unit 92. The angular velocity change amount calculation unit 91 of the present embodiment outputs a low-pass filter process applied to the angular velocity change amount Δωm to the regulation position determination angle acquisition unit 92.

The vehicle speed SPD, steering torque Th, q-axis current value Iq, motor angular velocity ωm, angular velocity change amount Δωm, and absolute steering angle θs are input to the regulated position determination angle acquisition unit 92. As will be described later, the regulation position determination angle acquisition unit 92 determines whether or not the movement of the rack shaft 12 to the left or right is restricted based on these state quantities, and the movement of the rack shaft 12 is restricted. Acquires the regulated position determination angle θi according to the absolute steering angle θs when it is determined that the steering angle is set.

A plurality of regulated position determination angles θi are input from the regulated position determination angle acquisition unit 92 to the end position corresponding angle setting unit 93. When the left side and right side regulation position determination angles θi are acquired, the end position correspondence angle setting unit 93 sets the end position correspondence angles θs_le and θs_re based on the regulation position determination angles θi on both the left and right sides. The end position corresponding angle setting unit 93 determines whether the regulated position determination angle θi is on either the left side or the right side based on the code of the regulated position determination angle θi.

Specifically, when the end position corresponding angle setting unit 93 acquires the regulation position determination angles θi on both the left and right sides, the absolute value of the regulation position determination angle θi on the left side and the absolute value of the regulation position determination angle θi on the right side are first obtained. The stroke width Wma, which is the sum, is calculated. Then, when the stroke width Wma is larger than the stroke threshold value Wth, the end position corresponding angle setting unit 93 sets the acquired left and right restricted position determination angles θi as the end position corresponding angles θs_le and θs_re, respectively. The stroke threshold value Wth is an angle range indicated by the absolute steering angle θs, and is set to a range slightly smaller than the angle 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 corresponding angle setting unit 93 does not set the end position corresponding angles θs_le and θs_re, discards the input restricted position determination angle θi, and regulates both the left and right sides. When the position determination angle θi is acquired again, the same processing is performed.

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

Next, acquisition of the regulated position determination angle θi by the regulated 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 larger than the low speed threshold value Slo, the regulated position determination angle acquisition unit 92 is restricted from moving the rack shaft 12. No judgment is made. This is because when the vehicle speed SPD is high to some extent, when the steering wheel 3 is steered to the rack end position, the vehicle spins or the like and the end contact does not occur. The regulated position determination angle acquisition unit 92 has an abnormal signal indicating the vehicle speed SPD, for example, when the vehicle speed SPD becomes an impossible value or when the amount of change from the previous value exceeds a preset threshold value. Is determined. 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 regulation position determination angle acquisition unit 92 performs a dynamic regulation determination when the signal indicating the vehicle speed SPD is abnormal or the vehicle speed SPD is equal to or less than the low speed threshold value Slo. Then, the regulation position determination angle acquisition unit 92 regulates according to the absolute steering angle θs when the dynamic regulation determination is continuously established for the first predetermined time and the determination is continuously established for the first predetermined time. Acquire the position determination angle θi. On the other hand, the regulation position determination angle acquisition unit 92 makes a static regulation determination when the dynamic regulation determination is not established. Then, the regulation position determination angle acquisition unit 92 regulates according to the absolute steering angle θs when the static regulation determination is continuously established for the second predetermined time and the determination is continuously established for the second predetermined time. Acquire the position determination angle θi.

The static regulation determination is a determination to detect a state in which the movement of the rack shaft 12 is restricted and the rudder is held, and a state in which the movement of the rack shaft 12 is restricted by slowly turning in and out. is there. The dynamic regulation determination is a determination to detect a state in which the turning steering is performed at a relatively high speed and the turning steering is performed immediately after the movement of the rack shaft 12 is restricted.

The regulation position determination angle acquisition unit 92 of the present embodiment sets the EPS 2 to the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted as a result of the dynamic regulation determination or the static regulation determination. Rigidity compensation that corrects based on the mechanical elastic deformation of EPS2 caused by the applied torque is performed, and the angle after the rigidity compensation is acquired as the regulation position determination angle θi.

Further, the regulated position determination angle acquisition unit 92 determines another regulated position from the acquisition of one regulated position determination angle θi until the peripheral environment change determination of whether or not the surrounding environment of the vehicle has changed is established. Do not get the angle θi.

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

(A1) The absolute value of the steering torque Th is equal to or greater than the first steering torque threshold value 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 larger than the first angular velocity threshold ωth1.

(A3) The sign of the angular velocity change amount Δωm is opposite to the sign of the steering torque Th, and the absolute value of the angular velocity change amount Δωm is larger than the first angular velocity change amount threshold Δωth1.
The first steering torque threshold value Tth1 is a steering torque when turning back steering is performed immediately after the rack end 18 comes into contact with the rack housing 13, and is set to an appropriate value larger than zero. The first angular velocity threshold value 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)
The regulation position determination angle acquisition unit 92 determines that the static regulation determination is satisfied and the movement of the rack shaft 12 is restricted when the following three conditions are satisfied.

(B1) The absolute value of the steering torque Th is equal to or greater than the second steering torque threshold value 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 larger than the first angular velocity threshold value ωth1 and equal to or less than the second angular velocity threshold value ωth2.

(B3) The absolute value of the angular velocity change amount Δωm is less than the second angular velocity change amount threshold value Δωth2.
The second steering torque threshold value Tth2 is the steering torque required to hold the steering wheel 3 when the vehicle is turned 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 value Tth1. The second angular velocity threshold value ωth2 is an angular velocity indicating that the motor 21 is rotating at a low speed, and is set to an appropriate value larger than zero. The second angular velocity change amount threshold value 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 value Δωth1 and slightly larger than zero. There is.

(Rigidity compensation)
The regulated position determination angle acquisition unit 92 subtracts the mechanical elastic deformation occurring in EPS2 from the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted, and subtracts the regulated position determination angle θi. Get as.

Specifically, the regulated position determination angle acquisition unit 92 calculates the pinion shaft torque Tp, which is the total value of the torques 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 regulated position determination angle acquisition unit 92 of the present embodiment has the steering torque Th applied to the driver, the motor torque based on the q-axis current value Iq, and the angular velocity change of the motor 21. The pinion shaft torque Tp is calculated using the inertial torque based on the quantity Δωm.

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

Here, as shown in FIG. 5, when the driver normally performs the steering operation, the steering wheel 4 steers according to the pinion shaft torque Tp applied to the EPS 2, and the absolute steering angle θs increases. Then, since the absolute steering angle θs corresponding to the actual rack end position is slightly exceeded, the absolute steering angle θs 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 contact, and the pinion shaft torque Tp increases, resulting in mechanical elastic deformation such as twisting of the steering shaft 11 constituting EPS2 and compression of the rack shaft 12. This is because the motor 21 rotates only 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 EPS2, the absolute steering angle θs at the position where the pinion shaft torque Tp becomes zero according to the inclination with the absolute steering angle θs as the base point. However, it almost matches the actual rack end position.

Based on this, the regulated position determination angle acquisition unit 92 calculates the rotation angle of the motor 21 based on the amount of elastic deformation of EPS2 by multiplying the elastic modulus Ke of EPS2 by the pinion shaft torque Tp. Then, the regulated position determination angle acquisition unit 92 acquires 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 as the regulated position determination angle θi.

(Judgment of changes in the surrounding environment)
When the following two conditions are satisfied, the regulated position determination angle acquisition unit 92 determines that the surrounding environment change determination is satisfied and that the surrounding environment of the vehicle has changed. However, when the signal indicating the vehicle speed SPD is abnormal, the regulated position determination angle acquisition unit 92 does not determine whether or not the condition (c2) is satisfied, and when the condition (c1) is satisfied. , Judge that the surrounding environment change judgment is established.

(C1) The cutback steering amount θba is equal to or greater than the cutback 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 equal to or greater than the traveling threshold value Smin.

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

(flowchart)
Next, an example of the processing procedure by the regulated position determination angle acquisition unit 92 will be described with reference to the flowcharts shown in FIGS. 6 to 9. In the following, for convenience of explanation, a case where the rack shaft 12 moves to the right and acquires the regulation position determination angle θi on the right side will be described. However, the rack shaft 12 moves to the left and the regulation position determination angle on the left side is obtained. The same process is performed when θi is acquired.

As shown in FIG. 6, when the regulated position determination angle acquisition unit 92 acquires various state quantities when acquiring the regulated position determination angle θi (step 101), the acquisition of the regulated position determination angle θi is permitted. It is determined whether or not the permission flag indicating that is set (step 102). The permission flag is set in the initial state, and is reset when the regulation position determination angle θi is acquired. The permission flag is set again when the surrounding 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 unit 92 does not execute the subsequent processing and does not acquire the regulation position determination angle θi in the same calculation cycle. On the other hand, when 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). When the signal indicating the vehicle speed SPD is normal (step 103: YES), it is determined whether or not the vehicle speed SPD is larger than the low speed threshold value Slo (step 104). Then, when the vehicle speed SPD is larger than the low speed threshold value Slo (step 104: YES), the subsequent processing is not executed, and the regulated position determination angle θi is not acquired in the same calculation cycle. On the other hand, when the signal indicating the vehicle speed SPD is not normal (step 103: NO) and when the vehicle speed SPD is equal to or less than the low speed threshold value Slo (step 104: NO), the dynamic regulation determination is performed (step 105).

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

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

As shown in FIG. 6, the regulation position determination angle acquisition unit 92 determines whether or not the determination is established after performing the dynamic regulation determination in step 105 (step 106). When the dynamic regulation determination is established (step 106: YES), the count value Cdy of the dynamic counter indicating the number of times the dynamic regulation determination is established is incremented (step 107), and the number of times the static regulation determination is established. Clear the count value Cst of the static counter indicating (step 108). Subsequently, it is determined whether or not the count value Cdy of the dynamic counter is equal to or greater than the predetermined count value Cth1 corresponding to the first predetermined time (step 109), and if the count value Cdy is less than the predetermined count value Cth1. (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 unit 92 clears the count value Cdy of the dynamic counter (step 110). Then, the rigidity is compensated for the absolute steering angle θs acquired in the same calculation cycle to acquire the regulated position determination angle θi (step 111), and the acquisition of the regulated position determination angle θi is stopped until the surrounding environment change determination is established. Set the stop flag (step 112).

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

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

As shown in FIG. 6, the regulation position determination angle acquisition unit 92 determines whether or not the determination is established after performing the static regulation determination in step 113 (step 114). When the static regulation 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 the 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, it is determined. (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 unit 92 clears the count value Cst of the static counter (step 118). Then, the absolute steering angle θs acquired in the same calculation cycle is subjected to rigidity compensation to acquire the regulated position determination angle θi (step 119), and the stop flag is set (step 120).

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

As shown in FIG. 9, in the surrounding environment change determination, when the regulation position determination angle acquisition unit 92 acquires various state quantities (step 401), it 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 regulated position determination angle θi has not been acquired and it is not necessary to determine whether or not the surrounding environment of the vehicle changes, then thereafter. Do not execute the processing of.

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

When 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 turn-back steering amount θba is equal to or less than the turn-back determination threshold value θth (step 404: NO), and when the vehicle speed SPD is less than the travel threshold value Smin (step 406: NO), the permission flag is reset (step). 409).

Next, the operation and effect of this embodiment will be described.
(1) For example, when the movement of the rack shaft 12 is restricted by the steering wheel 4 hitting the curb, the regulated position determination angle θi acquired at this time is the actual rack end as the actual end angle at which the end contact actually occurs. The angle deviates from the angle. Therefore, if the corresponding end position corresponding angles θs_le and θs_re are set based on only a single regulation position determination angle θi, the end position corresponding angles θs_le and θs_re tend to deviate from the actual rack end angle. Therefore, it is conceivable to set the end position corresponding angles θs_le and θs_re on the corresponding side based on the plurality of regulated position determination angles θi on either the left side or the right side. As a result, for example, even if one of the plurality of regulated position determination angles θi is acquired at the time of curb hitting, if the other regulated position determination angle θi is acquired at the time of end hitting, the set end position is set. It is possible to suppress that the corresponding angles θs_le and θs_re deviate from the actual rack end angle. However, for example, when a plurality of regulated position determination angles θi are obtained at the time of curb hitting, the end position corresponding to the corresponding side is supported based on the plurality of regulated position determination angles θi on either the left side or the right side. Even if the angles θs_le and θs_re are set, the corresponding end position angles θs_le and θs_re may deviate from the actual rack end angle.

In this regard, the regulation position determination angle acquisition unit 92 acquires the other regulation position determination angle θi after the surrounding environment of the vehicle changes after setting one regulation position determination angle θi. Therefore, it is possible to prevent any of the plurality of restricted position determination angles θi from becoming data acquired when the movement of the rack shaft 12 is restricted by hitting a curb or the like. This makes it possible to set the end position corresponding angles θs_le and θs_re that accurately correspond to the actual rack end angle.

(2) The conditions under which the ambient environment change determination is established include that the switchback steering amount θba is equal to or greater than the switchback determination threshold value θth and that the vehicle speed SPD is equal to or greater than the travel threshold value Smin. 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 regulated position determination angle acquisition unit 92 determines the rack shaft 12 when the vehicle speed SPD is equal to or less than the low speed threshold value Slo. Judge whether or not the movement of is restricted. Therefore, even if an abnormality occurs in the signal indicating the vehicle speed SPD, the regulated position determination angle θi can be acquired, so that the end position corresponding angles θs_le and θs_re can be set at an early stage. Further, when the signal indicating the vehicle speed SPD is abnormal, the regulated position determination angle acquisition unit 92 does not include the magnitude comparison between the vehicle speed SPD and the traveling threshold value Smin in the determination of the change in the surrounding environment. It is possible to prevent the surrounding environment change determination from being established due to an abnormality.

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

Here, for example, when the rack shaft 12 is swiftly moved to the right by the steering of the driver and the end contact occurs while the motor 21 is rotating quickly, the motor 21 tries to stop suddenly. Therefore, when the movement of the rack shaft 12 is restricted in such an embodiment, for example, in a state where a positive steering torque Th of the first steering torque threshold Tth1 or more is input, the angular velocity change amount Δωm of the motor 21 is a negative th. The angular velocity change threshold value is less than Δωth1. That is, when a momentary end guess occurs, a dynamic regulation judgment can be established. Therefore, in the present embodiment, it can be determined that the movement of the rack shaft 12 is restricted when, for example, quick turning is performed and momentary end contact occurs, and the regulated position determination angle θi is acquired to obtain the end position corresponding angle θs_le, θs_re can be set.

(5) As described above, for example, the rack shaft 12 is moved to the right by the steering of the driver, and the motor 21 moves the rack shaft 12 from the momentary end contact to the sudden stop of the motor 21. Rotate in the direction to move to the right. Therefore, as in the present embodiment, the condition for establishing the dynamic regulation determination includes that the motor angular velocity ωm is larger than the first angular velocity threshold value ωth1 having the same sign as the steering torque Th, so that the end can be momentarily guessed. Can be accurately determined whether or not has occurred.

(6) The regulation position determination angle acquisition unit 92 makes a static regulation determination, and when the static regulation determination is established, it is determined that the movement of the rack shaft 12 is restricted. The conditions under which the static regulation judgment is established are that the absolute value of the steering torque Th is greater than or equal to the 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 the first angular velocity. It is included that the second angular velocity change amount threshold is smaller than the change amount threshold value Δωth1 and is equal to or less than the second angular velocity change amount threshold value Δωth2.

Here, for example, when the rack shaft 12 moves to the right due to steering by the driver and end contact occurs, the motor 21 hardly rotates even if the incision steering is continued. Therefore, when the movement of the rack shaft 12 is restricted in such an embodiment, for example, in a state where a positive steering torque of the second steering torque threshold value Tth2 or more is input, the absolute value of the angular velocity change amount Δωm of the motor 21 is the second. The amount of change in angular velocity is Δωth2 or less. That is, if the steering is performed so as to hold the rudder after the end contact occurs, the static regulation determination can be established. Therefore, in the present embodiment, for example, when steering is performed such that the steering is held after the end contact occurs, it can be determined that the movement of the rack shaft 12 is restricted, and the regulated position determination angle θi is acquired to correspond to the end position. The angles θs_le and θs_re can be set.

(7) As described above, if the incision steering is continued even after the end contact occurs, the motor 21 rotates slightly due to the elastic deformation of the EPS2. Therefore, as in the above configuration, the condition that the static regulation determination is established 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 less than the second angular velocity threshold ωth2. By including it, it is possible to accurately determine whether or not continuous end hitting has occurred.

(8) The regulation position determination angle acquisition unit 92 makes a dynamic regulation determination and a static regulation determination, and moves the rack shaft 12 when either the dynamic regulation determination or the static regulation determination is established. Is regulated. Therefore, when the movement of the rack shaft 12 is restricted in various aspects, the regulated position determination angle θi can be acquired, and the end position corresponding angles θs_le and θs_re can be set at an early stage.

Here, for example, it is assumed that the turning steering is performed quickly, and after the steering wheel 4 hits a curb or the like and the movement of the rack shaft 12 is restricted, the turning steering is continuously performed as it is. In this case, since each of the dynamic regulation determination and the static regulation determination can be established, assuming that the regulation position determination angle θi is acquired when each determination is established, any of the two regulation position determination angles θi This is the data when the movement of the rack shaft 12 is restricted by hitting the same curb. Therefore, in the configuration in which each determination of the dynamic regulation determination and the static regulation determination is performed, the other regulation position determination is performed after the surrounding environment of the vehicle changes after setting one regulation position determination angle θi as in the present embodiment. The effect of acquiring the angle θi is great.

(9) The regulated position determination angle acquisition unit 92 mechanically generates EPS2 by the pinion shaft torque Tp applied to EPS2 with respect to the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted. The value obtained by performing rigidity compensation based on the elastic deformation is acquired as the regulation position determination angle θi. Therefore, an accurate regulation position determination angle θi can be obtained in consideration of the elastic deformation of EPS2 when it is determined that the movement of the rack shaft 12 is restricted.

(10) Since the regulated position determination angle acquisition unit 92 calculates the pinion shaft torque Tp based on the steering torque Th, the motor torque, and the inertial torque, the elasticity of the EPS 2 when it is determined that the movement of the rack shaft 12 is restricted. The amount of deformation can be calculated accurately, and a more accurate regulation position determination angle θi can be set. In particular, in the dynamic regulation determination, the inertia torque increases due to the sudden stop of the motor 21, and the effect is great.

This embodiment can be modified and implemented as follows. The present embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
-In the above embodiment, even when the signal indicating the vehicle speed SPD is normal and the vehicle speed SPD is larger than the low speed threshold value Slo, it may be determined whether or not the movement of the rack shaft 12 is restricted. 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 or not the movement of the rack shaft 12 is restricted.

-In the above embodiment, even when the signal indicating the vehicle speed SPD is abnormal, the magnitude comparison between the vehicle speed SPD and the traveling threshold value Smin may be included in the determination of the change in the surrounding environment.
-In the above embodiment, the regulation position determination angle acquisition unit 92 determines whether or not the movement of the rack shaft 12 is restricted by performing the dynamic regulation determination and the static regulation determination, but the present invention is not limited to this. It may be determined whether or not the movement of the rack shaft 12 is restricted by performing only one of the dynamic regulation determination and the static regulation determination.

-In the above embodiment, the conditions for determining the change in the surrounding environment are set to satisfy the above (c1) and (c2), but the present invention is not limited to this, and it is sufficient if it can be determined that the surrounding environment of the vehicle has changed. It is not necessary to determine the condition of c1). 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, a positioning signal from an artificial satellite for GPS (Global Positioning System) may be received, and it may be determined whether or not the position of the vehicle has changed by a predetermined distance or more based on the received positioning signal. Furthermore, for example, it may be determined that the surrounding environment of the vehicle has changed after a lapse of about several minutes, and the determination conditions for determining the change in the surrounding environment can be changed as appropriate.

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

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

-In the above embodiment, the pinion shaft torque Tp is calculated based on the steering torque Th, the motor torque, and the inertial torque, but the present invention is not limited to this, and is based on, for example, the steering torque Th and the motor torque for the purpose of reducing the calculation load. The pinion shaft torque Tp may be calculated. In addition, it is used for the pinion shaft torque Tp used for the rigidity compensation performed for the absolute steering angle θs acquired as a result of the dynamic regulation judgment, and for the rigidity compensation performed for the absolute steering angle θs acquired as a result of the static regulation judgment. The pinion shaft torque Tp may be different.

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

-In the above embodiment, when a plurality of regulated position determination angles θi on only one of the left side and the right side are acquired, 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, among a plurality of regulated position determination angles θi, the regulated position determination angle θi having the largest absolute angle may be set as the corresponding end position corresponding angles θs_le and θs_re.

-In the above embodiment, by monitoring the presence or absence of rotation of the motor 21 even when the ignition switch is turned off, the number of rotations 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 for detecting the steering angle in absolute angle is provided, and the rotation speed of the motor 21 from the origin is determined based on the steering angle detected by the steering sensor and the reduction ratio of the reduction mechanism 22. The absolute motor angle and the absolute steering angle θs may be detected by integrating.

-In the above embodiment, the end contact relaxation control is executed by limiting the assist command value Ias * to the rudder angle limit value Ien, but the present invention is not limited to this, and for example, the assist command value Ias * is set to the rack end position. The end contact relaxation control may be executed by adding a steering reaction force component that increases as the distance approaches, that is, a component whose sign is opposite to that of the assist command value Ias *.

-In the above embodiment, the guard processing is performed on the assist command value Ias *, but the present invention is not limited to this, and the assist command value Ias * is corrected by the compensation amount based on the torque differential value obtained by differentiating the steering torque Th. May be guarded.

In the above embodiment, the limit value setting unit 62 includes a voltage limit value calculation unit 72 that calculates the voltage limit value Ivb based on the power supply voltage Vb, but is not limited to this, and is added to the voltage limit value calculation unit 72. Alternatively, or instead, it may be provided with another calculation unit that calculates another limit value based on another state quantity. Further, 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 as the limit value Ig as it is.

-In the above embodiment, the value obtained by subtracting the angle limiting component Iga from the rated current Ir is set as the steering angle limiting value Ien, but the present invention is not limited to this, and the current determined according to the angle limiting component Iga from the rated current Ir and the motor angular velocity The 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 targets EPS2 in a form in which the EPS actuator 6 applies motor torque to the column shaft 15, but the control target is not limited to this, and the rack shaft 12 is not limited to this, for example, via a ball screw nut. A steering device of a type that applies motor torque to the vehicle may be controlled. Further, not limited to EPS, the steering control device 1 controls a steer-by-wire type steering device in which the power transmission between the steering unit operated by the driver and the steering unit that steers the steering wheel is separated. As for the torque command value or the q-axis current command value of the motor of the steering actuator provided in the steering section, the end contact relaxation control may be executed as in the present embodiment.

1 ... Steering control device, 2 ... Electric power steering device, 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 rudder angle detection unit, 65 ... End position corresponding angle management unit, 92 ... Restricted position determination angle acquisition unit, 93 ... End position corresponding angle setting unit, SPD ... Vehicle speed, Slo ... Low speed threshold, Smin ... Running threshold, Th ... Steering torque, Tth1 ... First steering torque threshold, Tth2 ... Second steering torque threshold, θm ... Rotation angle, θs ... Absolute steering angle, θi ... Restricted position determination angle, θs_le, θs_re ... End position Corresponding angle, θba… turning back steering amount, θth… turning back judgment threshold, ωm… motor angular speed, ωth1… first angular velocity threshold, ωth2… second angular velocity threshold, Δωm… angular velocity change amount, Δωth1… first angular velocity change amount threshold , Δωth2 ... Second angle velocity change amount threshold.

Claims (5)

A steering device including a housing, a steering shaft housed in the housing so as to be reciprocating, and an actuator for applying motor torque for reciprocating the steering shaft using a motor as a drive source is controlled.
Absolute steering angle detection unit that detects the absolute steering angle represented by the absolute angle including the range exceeding 360 °, which is the rotation angle of the rotating shaft that can be converted into the steering angle of the steering wheel connected to the steering shaft. When,
It is determined whether or not the movement of the steering shaft to the left or right is restricted, and the regulated position determination angle according to the absolute steering angle when it is determined that the movement of the steering shaft is restricted. And the regulation position judgment angle acquisition part to acquire
An end position that indicates that the steering axis is at the left or right end position based on the plurality of regulated position determination angles, and sets an end position corresponding angle associated with the absolute steering angle. Equipped with a corresponding angle setting unit
The regulated position determination angle acquisition unit acquires the other regulated position determination angle until the peripheral environment change determination of whether or not the surrounding environment of the vehicle has changed is established. Steering control device that does not get. In the steering control device according to claim 1,
A steering control device in which the condition for determining the change in the surrounding environment includes that the turning back steering amount is equal to or greater than the turning back determination threshold value. In the steering control device according to claim 1 or 2.
A steering control device including that the vehicle speed is equal to or higher than a traveling threshold value indicating a non-stop state of the vehicle, as a condition for establishing the surrounding environment change determination. In the steering control device according to claim 3,
The regulated position determination angle acquisition unit
Regardless of whether the signal indicating the vehicle speed input from the vehicle speed sensor is normal or not, when the vehicle speed is equal to or lower than the low speed threshold value indicating the low speed running of the vehicle, the movement of the steering shaft is restricted. It is to judge whether or not it is
When the signal indicating the vehicle speed is abnormal, the steering control device does not include the condition that the peripheral environment change determination is established that the vehicle speed is larger than the traveling threshold value. In the steering control device according to any one of claims 1 to 4.
The regulation position determination angle acquisition unit makes a dynamic regulation determination and a static regulation determination, and moves the steering axis when either the dynamic regulation determination or the static regulation determination is established. Is determined to be regulated,
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, respectively, and the sign of the steering torque for moving 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 regulation determination is satisfied are that the absolute value of the steering torque is equal to or greater than the first steering torque threshold value, and the sign of the amount of change in the angular velocity, which is the amount of change in the angular velocity of the motor, is the sign of the steering torque. Including that the absolute value of the angular velocity change amount is larger than the first angular velocity change amount threshold value.
The conditions under which the static regulation determination is established are that the absolute value of the steering torque is equal to or greater than the second steering torque threshold larger than the first steering torque threshold, and that the absolute value of the angular velocity change amount is the first. A steering control device including being equal to or less than a second angular velocity change amount threshold smaller than the angular velocity change amount threshold.

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