Turning control device

Abstract

To provide a turning control device configured to shorten a time required for determining whether an abnormality occurs.SOLUTION: A PU 72 maximally displaces a turning wheel 50 in a clockwise-turning direction. The PU 72 calculates a neutral position, in accordance with a turning corresponding angle at the time when the wheel is maximally displaced and a rack stroke length. The PU 72 controls the turning corresponding angle to the neutral position. The PU 72 determines whether an abnormality occurs in control, in accordance with whether an absolute value of an absolute angle θa detected by an absolute angle sensor 84 at the neutral position is equal to or less than threshold.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a steering control device.

Background Art

[0002] The following Patent Document 1 describes a system in which the power transmission between the steering wheel and the steered wheels is interrupted. The vehicle steering device in this system calculates the midpoint position of the steering angle. This device controls the steering motor to steer the steered wheels in the right direction to obtain the maximum right steering angle. Also, this device controls the steering motor to steer the steered wheels in the left direction to obtain the maximum left steering angle. And this device sets the midpoint between the maximum right steering angle and the maximum left steering angle as the neutral position of the steered wheels.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in the above processing, shortening the time required for the processing to ensure normal control of the steered wheels is required.

Means for Solving the Problems

[0005] Hereinafter, the means for solving the above problems and their effects will be described. 1. A steering control device in which a steering wheel is a control target and a motor for steering the steering wheel is an operation target, configured to execute a turning operation process, an end determination process, a maximum displacement variable acquisition process, and a determination process, wherein the turning operation process is a process of displacing the steering wheel to the maximum extent to either the right-turn side or the left-turn side by operating the motor, the end determination process is a process of determining whether the steering wheel has been displaced to the maximum extent, the maximum displacement variable acquisition process is a process of acquiring a value of a maximum displacement variable, the maximum displacement variable is a variable obtained based on being determined to have been displaced to the maximum extent by the end determination process, and the determination process is a process of determining the presence or absence of an abnormality in the control of the steering wheel based on the value of the maximum displacement variable.

[0006] The steering angle when the steering wheel is displaced to the maximum extent can be grasped in advance. Therefore, in the above configuration, based on the value of the maximum displacement variable obtained when displaced to the maximum extent, the presence or absence of an abnormality in the control of the steering wheel can be determined. Therefore, compared with the case of executing a process of displacing the steering wheel to the maximum extent to both the right-turn side and the left-turn side, the time required to determine the presence or absence of an abnormality can be shortened.

[0007] 2. The steering control device according to the above 1, wherein the value of the maximum displacement variable is an integrated value of the rotation angle of the motor when it is determined by the end determination process that the maximum displacement has occurred. According to the above configuration, the presence or absence of an abnormality can be determined according to the deviation between the steering angle when displaced to the maximum extent and the steering angle indicated by the integrated value.

[0008] 3. Configured to execute initial value acquisition processing, the turning operation processing includes processing for controlling the rotational speed of the motor to a target rotational speed. The maximum displacement variable is a variable indicating the elapsed time until it is determined by the end determination processing that the maximum displacement has occurred. The initial value acquisition processing is processing for acquiring the rudder equivalent angle at the start of counting the elapsed time. The rudder equivalent angle is a variable indicating the rudder angle of the rudder wheel. The determination processing is processing for determining the presence or absence of an abnormality in the control of the rudder wheel according to whether the elapsed time falls within a normal range determined from the target rotational speed and the value acquired by the initial value acquisition processing. The steering control device according to 1 above.

[0009] According to the value acquired by the above initial value acquisition processing and the rudder angle at the time of maximum displacement, it is possible to grasp the time required until maximum displacement when the motor is rotated at the target rotational speed. Therefore, a normal range for the above elapsed time can be determined. Therefore, with the above configuration, the presence or absence of an abnormality can be determined based on the elapsed time.

[0010] 4. Configured to execute midpoint variable calculation processing and midpoint movement processing, the midpoint variable calculation processing is processing for calculating the value of a midpoint variable, which is a variable indicating that the rudder wheel is in the neutral position, based on the value of the maximum displacement variable. The midpoint movement processing is processing for displacing the rudder wheel to the neutral position based on the value of the midpoint variable as an input variable. The steering control device according to any one of 1 to 3 above.

[0011] Since the value of the maximum displacement variable indicates the rudder angle when the rudder wheel is displaced to the maximum on the right turn side or the left turn side, the neutral position of the rudder wheel can be grasped according to the same value. Therefore, with the above configuration, the rudder wheel can be controlled to the neutral position.

[0012] 5. The end determination processing is processing for determining that the rudder wheel has been displaced to the maximum based on the logical product of the fact that the rudder angle of the rudder wheel does not change and the absolute value of the current of the motor being greater than or equal to a predetermined value. The steering control device according to any one of 1 to 4 above.

[0013] When the steering wheel is displaced to the maximum, the steering angle no longer changes. Moreover, if the motor is being driven at that time, the absolute value of the current of the motor becomes a predetermined value or more. Therefore, in the above configuration, when the above logical product is true, it can be determined that the maximum displacement has occurred.

[0014] 6. A steering control device comprising a storage device and configured to execute mode setting processing, wherein the mode setting processing includes processing for setting an operation mode to an inspection mode when the determination result of the determination processing is not stored in the storage device, and the turning operation processing, the end determination processing, the maximum displacement variable acquisition processing, and the determination processing are configured to be executed in the inspection mode. The steering control device according to any one of 1 to 5 above.

[0015] In the above configuration, by shifting to the inspection mode when the determination result is not stored, it is possible to suppress the execution of normal control without performing the determination processing.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0017] <First Embodiment> Hereinafter, the first embodiment will be described with reference to the drawings. "Configuration of Steering System" FIG. 1 shows the configuration of a vehicle steering system 10. The steering system 10 includes a steering device 20, a steering gear 30, a reaction force control device 60, and a steering control device 70.

[0018] The steering device 20 includes a steering wheel 12 and a steering shaft 14 mechanically connected to the steering wheel 12. A reaction force motor 16 is mechanically connected to the steering shaft 14. The reaction force motor 16 is used to apply a reaction force that resists the operation of the steering wheel 12 by the driver. The output voltage of an inverter 18 is applied to the terminals of the reaction force motor 16.

[0019] The steering gear 30 includes a rack shaft 32 and a pinion shaft 34. Rack teeth 32a are formed on the rack shaft 32. Pinion teeth 34a are formed on the pinion shaft 34. A rack and pinion mechanism 36 is configured by engaging the rack teeth 32a and the pinion teeth 34a.

[0020] The steering gear 30 includes a steering actuator ACT. The steering actuator ACT includes a steering motor 40, an inverter 42, a transmission mechanism 44, and a conversion mechanism 46. The transmission mechanism 44 transmits the rotation of the steering motor 40 to the conversion mechanism 46 via, for example, a belt. The conversion mechanism 46 includes, as an example, a ball screw mechanism. The conversion mechanism 46 converts the rotational displacement from the transmission mechanism 44 into the axial displacement of the rack shaft 32. The transmission mechanism 44 and the conversion mechanism 46 are conversion devices that convert the rotational power of the steering motor 40 into the axial displacement power of the rack shaft 32.

[0021] The steering wheel 50 is steered by the axial displacement of the rack shaft 32. The range within which the rack shaft 32 can be axially displaced is determined by the rack housing 48. In other words, the maximum value on the right turn side and the maximum value on the left turn side of the steering angle of the steering wheel 50 are determined by the positions where the stoppers 32b provided on the rack shaft 32 contact the rack housing 48.

[0022] The reaction force control device 60 includes a PU 62 and a storage device 64. The control target of the reaction force control device 60 is the steering device 20, and the operation target is the reaction force motor 16. The reaction force control device 60 controls the control amount of the control target by the PU 62 executing the program stored in the storage device 64.

[0023] The steering control device 70 includes a PU 72 and a storage device 74. The control target of the steering control device 70 is the steering wheel 50, and the operation target is the steering actuator ACT. The steering control device 70 controls the control amount of the control target by the PU 72 executing the program stored in the storage device 74. The steering control device 70 refers to the rotation angle θt of the steering motor 40 detected by the rotation angle sensor 82 for controlling the control amount. The steering control device 70 refers to the absolute angle θa detected by the absolute angle sensor 84 for controlling the control amount. The absolute angle θa is the rotation angle of the pinion shaft 34. The absolute angle θa is a variable having a one-to-one correspondence with the steering angle. As an example, the absolute angle θa has a positive value in the case of the right turn side and a negative value in the case of the left turn side value. For example, when the maximum value on the right turn side of the steering angle has a value greater than one rotation of the pinion shaft 34, the absolute angle θa can take an angle exceeding 360°. The steering control device 70 refers to the currents iut, ivt, iwt flowing through the steering motor 40. Note that the currents iut, ivt, iwt may be detected as the voltage drop amounts of the shunt resistors provided in each leg of the inverter 42.

[0024] The reaction force control device 60 and the steering control device 70 are communicable with each other. "Processing of the Steering Control Device" Fig. 2 shows the procedure of the process executed triggered by the activation of the steering control device 70. The process shown in Fig. 2 is realized by the PU72 repeatedly executing the program stored in the storage device 74, for example, at a predetermined period. Hereinafter, the step numbers of each process are represented by the numbers preceded by "S".

[0025] In the series of processes shown in Fig. 2, the PU72 first determines whether or not the power of the steering control device 70 has been switched from off to on (S10). When the PU72 determines that it has been switched (S10: YES), it determines whether or not the normal determination history data 74a is stored in the storage device 74 (S12). The normal determination history data 74a is data indicating that there is a history of a determination that it is normal in the inspection mode. When the PU72 determines that the normal determination history data 74a is stored (S12: YES), it sets the operation mode to the normal control mode (S14). The normal control mode is a mode that executes normal control in which the steering angle is the control amount. On the other hand, when the PU72 determines that the normal determination history data 74a is not stored (S12: NO), it sets the operation mode to the inspection mode (S16). The inspection mode is a mode that executes processes such as inspecting whether or not the control by the steering control device 70 is performed normally.

[0026] Note that when the processes of S14 and S16 are completed and when a negative determination is made in the process of S10, the PU72 temporarily ends the series of processes shown in Fig. 2. "Process in Inspection Mode" The inspection in the inspection mode is executed before the steering device 30 is mounted on the vehicle.

[0027] Fig. 3 shows the hardware configuration during inspection. As shown in Fig. 3, the steering control device 70 is connected to the equipment-side terminal 90. The equipment-side terminal 90 includes a PU92 and a storage device 94. The equipment-side terminal 90 causes the steering control device 70 to execute an inspection by the PU92 executing the program stored in the storage device 94.

[0028] Figure 4 shows the procedure of the inspection process. The process shown in Figure 4 is realized by the PU 72 repeatedly executing the program stored in the storage device 74, for example, at a predetermined cycle.

[0029] In the series of processes shown in Figure 4, the PU 72 first determines whether the operation mode is the inspection mode (S20). When the PU 72 determines that the operation mode is the inspection mode (S20: YES), it determines whether the end fitting process is being executed (S22). When the PU 72 determines that the end fitting process is not being executed (S22: NO), it determines whether an end fitting command has been input from the equipment side terminal 90 to the steering control device 70 (S24). When the PU 72 determines that the command has been input (S24: YES), it receives the data indicating the guard values Δ1 to Δ3 output by the equipment side terminal 90 (S26). Also, the PU 72 receives the change angles θp1 and θp2 output by the equipment side terminal 90 (S28). Then the PU 72 starts the end fitting process (S30).

[0030] Next, the PU 72 calculates a steering equivalent angle θp based on the rotation angle θt as an input variable (S32). The steering equivalent angle θp is a variable indicating the steering angle of the steering wheel 50. In this embodiment, as an example, the steering equivalent angle θp is the rotation angle of the pinion shaft 34. Then the PU 72 calculates a target steering equivalent angle θp* which is the target value of the steering equivalent angle θp (S34). Next, the PU 72 calculates a target torque Tt* corresponding to the operation amount by feedback control in which the steering equivalent angle θp is the control amount and the target steering equivalent angle θp* is the target value of the control amount (S36). The target torque Tt* is the torque of the steering motor 40.

[0031] Then, the PU 72 outputs an operation signal MSt of the inverter 42 to the inverter 42 to bring the torque of the steering motor 40 closer to the target torque Tt* (S38). On the other hand, when determining that the end fitting process is being executed (S22: YES), PU72 determines whether or not the end fitting process has been completed (S40). When determining that the end fitting process has not been completed yet (S40: NO), PU72 proceeds to the process of S32.

[0032] On the other hand, when determining that the end fitting process has been completed (S40: YES), when making a negative determination in the processes of S20 and S24, and when completing the process of S38, PU72 temporarily ends the series of processes shown in FIG. 4.

[0033] FIG. 5 shows the details of the process of S34. In the series of processes shown in FIG. 5, PU72 determines whether or not the control mode of the steering wheel 50 in the end fitting process is the right turn mode (S50). The right turn mode is a mode for executing a process of steering the steering wheel 50 to the right turn side. As an example, PU72 sets the right turn mode at the start of the end fitting process.

[0034] When determining that it is the right turn mode (S50: YES), PU72 determines whether or not the target steering equivalent angle θp* is greater than or equal to the change angle θp1 (S52). When determining that the target steering equivalent angle θp* is less than the change angle θp1 (S52: NO), PU72 substitutes the guard value Δ1 into the change amount Δ (S54). The change amount Δ defines the change amount of the target steering equivalent angle θp* per predetermined time. In other words, the change amount Δ defines the change speed of the target steering equivalent angle θp*. On the other hand, when determining that the target steering equivalent angle θp* is greater than or equal to the change angle θp1 (S52: YES), PU72 substitutes the guard value Δ2 into the change amount Δ (S56). The guard values Δ1 and Δ2 are positive values, and the guard value Δ1 is set to a value larger than the guard value Δ2.

[0035] When completing the processes of S54 and S56, PU72 substitutes the value obtained by adding the change amount Δ to the target steering equivalent angle θp* into the target steering equivalent angle θp* (S58). Then, PU72 determines whether or not the logical product of the following conditions (A) and (B) has been true for a certain period of time (S60).

[0036] Condition (A) is a condition that the previous value "θp(n - 1)" and the current value "θp(n)" of the rudder equivalent angle θp are the same. Condition (B) is a condition that the absolute value of the q-axis current iqt flowing through the steering motor 40 is equal to or greater than the threshold value Ith. The threshold value Ith is set to a value greater than the value assumed as the absolute value of the q-axis current iqt when steering the steering wheel 50 when the steering angle is in the intermediate region between the upper limit values on the right turn side and the left turn side. For example, when the feedback control in the process of S38 includes a proportional term, the threshold value Ith may be set to be equal to or greater than the output value of the proportional term when the absolute value of the difference between the target rudder equivalent angle θp* and the rudder equivalent angle θp becomes the guard value Δ2. Further, when the feedback control in the process of S38 includes an integral term, the threshold value Ith may be a value for determining that the integral term windup phenomenon has occurred. Note that the q-axis current iqt is calculated by the PU72 based on the rotation angle θt and the currents iut, ivt, iwt as input variables.

[0037] The above conditions (A) and (B) are conditions for specifying that the steering angle has reached the upper limit value on the right turn side. When the PU72 determines that the state in which the logical product of conditions (A) and (B) is true continues for a certain period of time (S60: YES), the current value "θp(n)" of the rudder equivalent angle θp is substituted into the target rudder equivalent angle θp* (S62). Then, the current value "θp(n)" is substituted into the right upper limit value θpR, and the control mode is set to the midpoint movement mode (S64).

[0038] PU72 substitutes, into the left upper limit value θpL, the value obtained by subtracting the rack stroke length θLR from the right upper limit value θpR (S66). The rack stroke length θLR indicates the magnitude of the displaceable angular range of the equivalent steering angle θp. This angular range is the length of the region from the state where the stopper 32b contacts the rack housing 48 when the rack shaft 32 is displaced maximally to the right, to the state where the stopper 32b contacts the rack housing 48 when the rack shaft 32 is displaced maximally to the left. Note that the rack stroke length θLR is acquired by PU72 reading out the stroke length data 74b stored in the storage device 74.

[0039] PU72 substitutes "1 / 2" of the sum of the right upper limit value θpR and the left upper limit value θpL into the midpoint θpmd (S68). Thereafter, PU72 determines whether or not the equivalent steering angle θp coincides with the midpoint θpmd by making a negative determination in the process of S50 (S70). When PU72 determines that the equivalent steering angle θp does not coincide with the midpoint θpmd (S70: NO), it substitutes the guard value Δ3 into the change amount Δ (S72). The guard value Δ3 is a positive value and is set to a value larger than the guard value Δ2. The guard value Δ3 may be equal to the guard value Δ1. Then, PU72 substitutes the value obtained by subtracting the change amount Δ from the target equivalent steering angle θp* into the target equivalent steering angle θp* (S74).

[0040] On the other hand, when PU72 determines that the equivalent steering angle θp coincides with the midpoint θpmd (S70: YES), it acquires the latest absolute angle θa detected by the absolute angle sensor 84 (S76). Next, PU72 determines whether or not the absolute value of the absolute angle θa is less than or equal to the threshold value θath (S80). The process of S80 is a process for determining whether or not the absolute angle θa has been acquired normally. That is, in the state where an affirmative determination has been made in the process of S70, it is considered that the absolute angle θa is a value close to zero. Therefore, when the absolute angle θa deviates greatly from zero, it is considered that there is some abnormality.

[0041] When PU72 determines that the absolute value is less than or equal to the threshold value θath (S80: YES), it determines that the software process executed by PU72 is normal and stores normal determination history data 74a in the storage device 74 (S82). Then, PU72 completes the end fitting process (S84). On the other hand, when PU72 determines that the absolute value is greater than the threshold value θath (S80: NO), it determines that there is an abnormality in the software process (S86).

[0042] Note that when PU72 completes the processes of S68, S74, S84, and S86, and when a negative determination is made in the process of S60, the series of processes shown in FIG. 5 are temporarily terminated. <Operations and Effects of the Present Embodiment> FIG. 6 illustrates an end fitting process.

[0043] As shown in FIG. 6, when an end fitting command from the facility-side terminal 90 is input to the steering control device 70, after time t1, PU72 increases the target steering equivalent angle θp* at a speed defined by the guard value Δ1. Thereby, the steering equivalent angle θp indicating the steering angle of the steering wheel 50 is controlled to follow the target steering equivalent angle θp*. At the time t2 when the target steering equivalent angle θp* reaches the change angle θp1, PU72 changes the change speed of the target steering equivalent angle θp* to the speed defined by the guard value Δ2. Thereafter, when the target steering equivalent angle θp* reaches the right upper limit value θpR at time t3, the steering equivalent angle θp no longer increases. Therefore, at time t4, PU72 decreases the target steering equivalent angle θp* to the steering equivalent angle θp.

[0044] Then, PU72 decreases the target steering equivalent angle θp* at a speed defined by the guard value Δ3. When the steering equivalent angle θp reaches the midpoint θpmd at time t5, PU72 acquires the absolute angle θa. When the absolute value of the absolute angle θa is less than or equal to the threshold value θath, PU72 stores the normal determination history data 74a in the storage device 74.

[0045] In this way, PU72 obtains the right upper limit value θpR by turning the steering wheel 50 to the right to the maximum extent. Then, based on the rack stroke length θLR as the input variable and the right upper limit value θpR, PU72 calculates the midpoint θpmd. PU72 displaces the equivalent steering angle θp to the midpoint θpmd. The equivalent steering angle θp at this time should be zero. Therefore, the absolute angle θa should also be zero. So, when the absolute value of the absolute angle θa is less than or equal to the threshold value θath, PU72 determines that the control is normal. That is, PU72 determines that the equivalent steering angle θp calculated by integrating the rotation angle θt is an appropriate value for use in control and that the steering wheel 50 can be steered normally.

[0046] This determination is achieved without executing the process of turning the steering wheel to the left to the maximum extent. Therefore, compared with the case of executing the process of turning the steering wheel to the left to the maximum extent, the time required for the above determination can be shortened.

[0047] In addition, according to the above embodiment, the following operations and effects can be further obtained. (1) While reducing the steering angular velocity midway, the equivalent steering angle is made to reach the right upper limit value θpR. Therefore, it is possible to preferably achieve both shortening the time required for the equivalent steering angle θp to reach the midpoint θpmd and suppressing an impact from being applied to the steering device 30. That is, when the target equivalent steering angle θp* is changed by PU72 at a speed defined by the guard value Δ1, a large impact occurs when the equivalent steering angle θp reaches the right upper limit value θpR. In contrast, when the target equivalent steering angle θp* is changed by PU72 at a speed defined by the guard value Δ2, the impact when the equivalent steering angle θp reaches the right upper limit value θpR can be alleviated. However, in that case, the time required for the equivalent steering angle θp to reach the midpoint θpmd becomes longer.

[0048] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the drawings, centering on the differences from the first embodiment.

[0049] Figure 7 shows the details of the process of S34. In Figure 7, for the processes corresponding to the processes shown in Figure 5, the same step numbers are given for convenience. In the series of processes shown in Figure 7, when PU72 makes an affirmative determination in the process of S50, it determines whether it is the start time of the right turn mode (S90). When PU72 determines that it is the start time (S90: YES), it substitutes the rudder equivalent angle θp at that time into the initial value θp0 (S92). When PU72 completes the process of S92 and when it makes a negative determination in the process of S90, it executes the processes of S54 and S58 and adds the cycle Tc to the counter T (S94). The cycle Tc is the execution cycle of the series of processes shown in Figure 7. The counter T is a variable that measures the period during which the processes of S32 to S38 are executed according to the processes of S54 and S58. Then PU72 proceeds to the process of S60.

[0050] When PU72 makes an affirmative determination in the process of S60, it determines whether the following equation holds (S80a). |2·[Δ·{T - (constant time)} / Tc + θp0] - θLR| ≦ θath Here, "T - (constant time)" can be regarded as the time during which the rudder equivalent angle θp has changed. It is desirable that the "constant time" here be a constant time from the point in time when condition (A) is satisfied instead of the constant time as the duration of the state in which conditions (A) and (B) are satisfied. Also, "Δ / Tc" indicates the change rate of the rudder equivalent angle θp. Therefore, "Δ·{T - (constant time)} / Tc" is the amount by which the rudder equivalent angle θp has turned to the right. Also, "Δ·{T - (constant time)} / Tc + θp0" indicates the right upper limit value θpR. Therefore, "2·[Δ·{T - (constant time)} / Tc]" should be an amount equivalent to the rack stroke length θLR. Therefore, the process of S80a is a process of determining whether the rudder equivalent angle θp calculated by integrating the rotation angle θt is an appropriate value for control. Also, the process of S80a is a process of determining whether the rudder wheel 50 can be steered normally.

[0051] When making an affirmative determination in the process of S80a, PU72 executes the process of S82 and switches to the midpoint movement mode (S64a). Then, PU72 substitutes "1 / 2" of "2·[Δ·{T - (constant time)} / Tc + θp0] - θLR" into the midpoint θpmd (S68a). On the other hand, when making a negative determination in the process of S80a, after executing the process of S86, PU72 temporarily ends the series of processes shown in FIG. 7.

[0052] On the other hand, when making an affirmative determination in the process of S70, PU72 proceeds to the process of S84. <Corresponding relationship> The corresponding relationship between the matters in the above embodiment and the matters described in the column of "Means for Solving the Problems" is as follows. Hereinafter, the corresponding relationship is shown for each number of the solution means described in the column of "Means for Solving the Problems". [1,5] The turning operation process corresponds to the processes of S36 and S38 in FIG. 4 corresponding to the processes of S50 to S58 in FIG. 5, and the processes of S36 and S38 in FIG. 4 corresponding to the processes of S50, S54, and S58 in FIG. 7. The end determination process corresponds to the process of S60. The maximum displacement variable acquisition process corresponds to the process of S64 in FIG. 5 and the process of S94 at the time when an affirmative determination is made in the process of S60 in FIG. 7. The determination process corresponds to the processes of S66 to S82 and S86 in FIG. 5, and the processes of S80a, S82, and S84 in FIG. 7. [2] The maximum displacement variable corresponds to the right upper limit value θpR. [3] The turning operation process corresponds to the processes of S36 and S38 in FIG. 4 corresponding to the processes of S50, S54, and S58 in FIG. 7. The target rotation speed corresponds to "Δ / T". The maximum displacement variable corresponds to the counter T at the time when an affirmative determination is made in the process of S60. The initial value acquisition process corresponds to the process of S92. [4] The midpoint variable calculation process corresponds to the processes of S68 and S68a. The midpoint movement process corresponds to the processes of S36 and S38 when the processes of S72 and S74 are being executed. [6] The mode setting process corresponds to the processes of S12 to S16.

[0053] <Other embodiments> Note that this embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

[0054] "Regarding the determination process" · In the process of FIG. 5, instead of the process of S80, after the execution of the process of S68, a process of determining whether or not the absolute value of the midpoint θpmd is less than or equal to the threshold value θath may be executed. In other words, it is not essential for the input variable of the determination process for the presence or absence of an abnormality to include the absolute angle θa when the steering equivalent angle θp is made to coincide with the midpoint θpmd.

[0055] · In the process of FIG. 7, instead of the process of S80a, a process of S80 may be provided in the same manner as the process of FIG. 5. In that case, the process of S80 also serves as a process of indirectly determining whether or not the elapsed time required until the maximum displacement falls within the normal range determined from the initial value θp0 and the guard value Δ1.

[0056] · For performing the determination of the presence or absence of an abnormality based on the elapsed time required until the maximum displacement, it is not essential for the change speed of the target steering equivalent angle θp* until the maximum displacement to be constant. For example, as shown in FIG. 5, the change speed of the target steering equivalent angle θp* may be changed. Even in that case, the normal range of the elapsed time can be set based on the initial value θp0 and the timing at which the target steering equivalent angle θp* is changed.

[0057] "Regarding the turning operation process" · In the turning operation process, the number of times the turning speed is changed does not have to be 1, and may be 2 or more.

[0058] ·The condition for determining that PU72 has reached the right upper limit value θpR is not limited to the condition where the logical product of the above conditions (A) and (B) is true for a certain period of time. The condition for determining that PU72 has reached the right upper limit value θpR may be, for example, the condition that the above condition (A) holds for a certain period of time. Also, for example, when the threshold value Ith is set as the value for determining that the windup phenomenon of the integral term has occurred, the condition for determining that PU72 has reached the right upper limit value θpR may be the condition that the above condition (B) holds.

[0059] ·When it is determined that PU72 has reached the right upper limit value θpR, it is not essential to execute the process of substituting the steering equivalent angle θp into the target steering equivalent angle θp*. For example, when it is determined that PU72 has reached the right upper limit value θpR, PU72 may gradually decrease the target steering equivalent angle θp* according to the guard value Δ1.

[0060] ·It is not essential that the control amount of the feedback control in the right turn operation process is the steering equivalent angle θp. For example, the control amount of the feedback control in the right turn operation process may be the change speed of the steering equivalent angle θp. Also, for example, the control amount of the feedback control in the right turn operation process may be the absolute angle θa.

[0061] ·It is not essential that the turning operation process is a process of turning the steering wheel 50 to the right. For example, the turning operation process may be a process of turning the steering wheel 50 to the left. "Regarding the end fitting process" ·It is not essential that the end fitting process is executed before the steering device 30 is mounted on the vehicle. For example, the end fitting process may be executed immediately after the steering device 30 is mounted on the vehicle. In that case, for example, if the steering control device 70 is mounted on the vehicle and the steering control device 70 can communicate with the equipment side terminal 90, the end fitting process can be executed in the same manner as in the above embodiment.

[0062] "Regarding the absolute angle sensor" · The absolute angle sensor, which is a sensor that detects an amount corresponding one-to-one to the steering angle of the steering wheel 50, is not limited to the sensors exemplified in the above embodiment. For example, it may be a linear stroke sensor that directly detects the amount of displacement of the rack shaft 32 in the axial direction.

[0063] "Regarding the Steering Control Device" · It is not essential that the guard values Δ1, Δ2, Δ3 be input from the facility-side terminal 90 to the steering control device 70. For example, the guard values Δ1, Δ2, Δ3 may be stored in advance in the storage device 74 of the steering control device 70.

[0064] · It is not essential that the change angles θp1, θp2 be input from the facility-side terminal 90 to the steering control device 70. For example, the change angles θp1, θp2 may be stored in advance in the storage device 74 of the steering control device 70.

[0065] · The steering control device is not limited to one that executes software processing. For example, at least a part of the processing executed in the above embodiment may be executed by hardware processing, and a dedicated hardware circuit such as an ASIC may be provided. That is, the steering control device may include a processing circuit having any of the following configurations (a) to (c). (a) A processing circuit including a processing device that executes all of the above processing according to a program and a program storage device such as a storage device that stores the program. (b) A processing circuit including a processing device and a program storage device that execute a part of the above processing according to a program and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit including a dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices including a processing device and a program storage device. Also, there may be a plurality of dedicated hardware circuits.

[0066] "Regarding the Steering Control System" ·When the equipment-side terminal 90 does not input the guard values Δ1, Δ2, Δ3 and the change angles θp1, θp2 to the steering control device 70, the equipment-side terminal 90 may only have the function of outputting a command for executing the end contact process to the steering control device 70.

Explanation of Signs

[0067] 10…Steering system 12…Steering wheel 14…Steering shaft 16…Reaction motor 18…Inverter 20…Steering device 30…Steering gear 32…Rack shaft 32a…Rack teeth 32b…Stopper 34…Pinion shaft 34a…Pinion teeth 36…Rack and pinion mechanism 40…Steering motor 42…Inverter 44…Transmission mechanism 46…Conversion mechanism 48…Rack housing 50…Steering wheel 60…Reaction control device 70…Steering control device 90…Equipment-side terminal

Claims

1. A steering control device in which a steering wheel is a control target and a motor for steering the steering wheel is an operation target, configured to execute a turning operation process, an end determination process, a maximum displacement variable acquisition process, and a determination process, wherein the turning operation process is a process of displacing the steering wheel to the maximum extent to either the right turning side or the left turning side by operating the motor, the end determination process is a process of determining whether or not the steering wheel has been displaced to the maximum extent, the maximum displacement variable acquisition process is a process of acquiring a value of a maximum displacement variable, the maximum displacement variable is a variable obtained based on being determined to have been displaced to the maximum extent by the end determination process, and the determination process is a process of determining the presence or absence of an abnormality in the control of the steering wheel based on the value of the maximum displacement variable.

2. The steering control device according to claim 1, wherein the value of the maximum displacement variable is an integrated value of the rotation angle of the motor when it is determined by the end determination process that the maximum displacement has occurred.

3. configured to execute an initial value acquisition process, wherein the turning operation process includes a process of controlling the rotation speed of the motor to a target rotation speed, the maximum displacement variable is a variable indicating the elapsed time until it is determined by the end determination process that the maximum displacement has occurred, the initial value acquisition process is a process of acquiring a steering equivalent angle at the start of the measurement of the elapsed time, the steering equivalent angle is a variable indicating the steering angle of the steering wheel, and the determination process is a process of determining the presence or absence of an abnormality in the control of the steering wheel according to whether or not the elapsed time falls within a normal range determined from the target rotation speed and the value acquired by the initial value acquisition process.

4. configured to execute a midpoint variable calculation process and a midpoint movement process, wherein the midpoint variable calculation process is a process of calculating a value of a midpoint variable, which is a variable indicating that the steering wheel is in a neutral position, based on the value of the maximum displacement variable, and the midpoint movement process is a process of displacing the steering wheel to the neutral position based on the value of the midpoint variable as an input variable.

5. The end determination process according to claim 1, wherein the end determination process determines that the steering wheel has been displaced to the maximum based on the logical product of the fact that the steering angle of the steering wheel does not change and the absolute value of the current of the motor being equal to or greater than a predetermined value.

6. Comprising a storage device, configured to execute mode setting processing, the mode setting processing includes processing for setting the operation mode to an inspection mode when the determination result of the determination processing is not stored in the storage device, The steering control device according to claim 1, wherein the turning operation process, the end determination process, the maximum displacement variable acquisition process, and the determination process are configured to be executed in the inspection mode.

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