Steering control apparatus

Abstract

A steering control apparatus (1) comprises a learning unit (61, 62), an absolute angle calculating unit (66), and a detection unit (68). While a vehicle is driving straight ahead, the learning unit learns a steering neutral point (θ01, θ02) to obtain a learned value. The absolute angle calculating unit calculates a steering angle (θs) on the basis of a current value (θ0) of the steering neutral point, and transmits the calculated steering angle to an external apparatus (52). When the vehicle power is turned on, the detection unit detects an abnormality that affects the learning of the steering neutral point learning and the calculation of the steering angle, and when an abnormality is detected, the detection unit executes a process for initializing the current value and the learned value of the steering neutral point. Upon completion of the process for initializing the current value and the learned value of the steering neutral point, the absolute angle calculating unit transmits, to the external apparatus, an electric signal (F16) indicating the completion of the process.

Description

Steering control system

[0001] This disclosure relates to a steering control device.

[0002] For example, the steering control device described in Patent Document 1 controls the steering device of a vehicle. The steering device is, for example, an electric power steering device and has a motor. The motor generates assist torque to assist in steering the steering wheel. The steering control device has two control units. The control units calculate the steering angle based on the number of rotations and rotation angle of the motor obtained from a rotation angle sensor and the steering angle midpoint corresponding to the neutral position of the steering wheel.

[0003] For example, if a malfunction occurs in one of the two control systems, it may become impossible to continue calculating the motor's rotation count. In this case, when the vehicle power is turned on, the control system of the malfunctioning system obtains the motor's rotation count and the midpoint of the steering angle from the control system of the normal system. This allows the control system of the malfunctioning system to properly calculate the steering angle even if a malfunction occurs in one of the two control systems.

[0004] Japanese Patent Publication No. 2018-177099

[0005] The steering angle midpoint or steering angle calculated by the steering control device may be used by the vehicle control device installed in the vehicle. However, in the steering control device of Patent Document 1, there may be a period after the vehicle power is turned on in which abnormal and normal steering angle midpoints coexist. Therefore, there is a concern that the vehicle control device may use an incorrect steering angle midpoint or steering angle to control the vehicle.

[0006] A steering control device according to one aspect of the present disclosure is configured to control the steering of a vehicle using the steering angle midpoint of a steering wheel. The steering control device comprises a learning unit, an absolute angle calculation unit, and a detection unit. The learning unit is configured to learn the steering angle midpoint when the vehicle is moving in a straight line and to obtain a learned value. The absolute angle calculation unit is configured to calculate the steering angle of the steering wheel as an absolute steering angle based on the current value of the steering angle midpoint and to transmit the calculated steering angle to an external device mounted on the vehicle. The detection unit is configured to detect any abnormalities that affect the learning of the steering angle midpoint and the calculation of the steering angle when the vehicle power is turned on, and to execute a process to initialize the current value and the learned value of the steering angle midpoint when such abnormalities are detected. The absolute angle calculation unit is configured to transmit an electrical signal to the external device indicating that the process of initializing the current value and the learned value of the steering angle midpoint has been completed.

[0007] Figure 1 is a configuration diagram of a steering device equipped with one embodiment of the steering control device. Figure 2 is a block diagram of the steering control device of Figure 1. Figure 3 is a block diagram of the calculation circuit of Figure 2. Figure 4 is a flowchart showing the procedure of the abnormality detection process performed by the detection unit of Figure 3.

[0008] A steering control device according to one embodiment will be described. As shown in Figure 1, the steering control device 1 controls the vehicle's steering device 2. The steering device 2 is, for example, an electric power steering device. The electric power steering device assists in steering the steering wheel 3. The steering wheel 3 and the vehicle's steering wheels 4 are mechanically connected to enable mechanical power transmission. The steering wheels 4 are steered in accordance with the steering of the steering wheel 3.

[0009] The steering system 2 includes a steering shaft 20, a pinion shaft 21, a steering shaft 22, and a housing 23. The first end of the steering shaft 20 is connected to the steering wheel 3. The second end of the steering shaft 20 is connected to the pinion shaft 21 via a universal joint. The pinion shaft 21 is rotatably supported in the housing 23.

[0010] The housing 23 houses the steering shaft 22 so that it can reciprocate. The steering shaft 22 extends in a direction intersecting the pinion shaft 21. The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Steering wheels 4 are connected to both ends of the steering shaft 22 via rack ends 24 and tie rods 25, which are ball joints.

[0011] The steering shaft 20, pinion shaft 21, and steering shaft 22 constitute the vehicle's steering mechanism. The steering device 2 includes a motor 31, a transmission mechanism 32, and a conversion mechanism 33. The motor 31 is, for example, a three-phase brushless motor and functions as an assist motor that generates assist force. The assist force is the torque of the motor 31 that assists in steering the steering wheel 3. The transmission mechanism 32 is a belt transmission mechanism that transmits the rotation of the motor 31 to the conversion mechanism 33. The conversion mechanism 33 is a ball screw mechanism that converts the rotation transmitted via the transmission mechanism 32 into axial motion of the steering shaft 22.

[0012] When the steering shaft 22 moves axially, the steering angle θ of the steering wheel 4 changes. ｗ This changes. The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Therefore, the pinion shaft 21 rotates in conjunction with the movement of the steering shaft 22. The pinion shaft 21 is a shaft that rotates in conjunction with the steering action of the steering wheel 4.

[0013] The steering wheel 3, steering shaft 20, and pinion shaft 21 rotate as a single unit. Therefore, the pinion angle θ, which is the rotation angle of the pinion shaft 21, is used. ｐ This is the steering angle θ, which is the rotation angle of the steering wheel 3. ｓ This is equal to:

[0014] The steering control device 1 has a processing circuit that includes one of the following three configurations A1, A2, and A3: A1. One or more processors that operate according to a computer program which is software. The processor includes a CPU (Central Processing Unit) and memory.

[0015] A2. One or more dedicated circuits, such as application-specific integrated circuits (ASICs), that perform at least some of the various processes. The ASIC may include a CPU and memory. A3. A circuit that combines configurations A1 and A2.

[0016] Memory is a medium readable by a computer that stores programs describing processes or instructions for the computer. In this embodiment, the computer is the CPU. Memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU performs various controls by executing the programs stored in memory at predetermined calculation cycles.

[0017] The steering control device 1 acquires detection results from on-board sensors. The sensors include a vehicle speed sensor 41, a torque sensor 42, and a rotation angle sensor 43. The vehicle speed sensor 41 detects the vehicle speed V. The vehicle speed V is a state variable that reflects the driving state of the vehicle.

[0018] The torque sensor 42 is installed on the steering shaft 20. The torque sensor 42 measures the steering torque T applied to the steering shaft 20. ｈ It detects steering torque T. ｈ This is calculated based on the amount of twist of the torsion bar 42a provided on the steering shaft 20. Steering torque T ｈ This is a state variable that reflects the steering state of the steering wheel 3.

[0019] The rotation angle sensor 43 is provided on the motor 31. The rotation angle sensor 43 measures the rotation angle θ of the motor 31. ｍ It detects the rotation angle θ. ｍis a relative angle within the range from 0° to 360°. The rotation angle sensor 43 is, for example, a magnetic sensor or a resolver. The magnetic sensor includes a Hall sensor or an MR sensor (magnetoresistive effect sensor).

[0020] The steering control device 1 executes assist control. The assist control is control for generating an assist force in the motor 31 according to the steering state of the steering wheel 3. The steering control device 1 uses, for example, the vehicle speed V detected by the vehicle speed sensor 41, the steering torque T detected by the torque sensor 42 ｈ , and the rotation angle θ of the motor 31 detected by the rotation angle sensor 43 ｍ to control the operation of the motor 31. The steering control device 1 controls the power supply to the motor 31 so as to generate an assist force corresponding to the steering torque T ｈ and the vehicle speed V in the motor 31.

[0021] The steering control device 1 uses the steering angle θ ｓ of the steering wheel 3 to execute various compensation controls, thereby realizing a better steering feeling. The compensation control includes, for example, steering return control. The steering return control is control for appropriately returning the steering wheel 3 to the steering neutral position based on the steering angle θ ｓ . The steering neutral position is the rotational position of the steering wheel 3 corresponding to the straight-ahead state of the vehicle.

[0022] <Configuration of the Steering Control Device> Next, the configuration of the steering control device 1 will be described in detail. As shown in FIG. 2, the steering control device 1 includes an arithmetic circuit 51, a drive circuit 52, and a processing circuit 53.

[0023] The arithmetic circuit 51 takes in the rotation angle θ ｍ of the motor 31 detected by the rotation angle sensor 43. The arithmetic circuit 51 calculates the steering angle θ ｍ using the rotation angle θ ｓ of the motor 31. The steering angle θ ｓ is an absolute angle and may exceed 360°. The arithmetic circuit 51 transmits the steering angle θ ｓThe data may also be transmitted to an external device 54. The in-vehicle network is, for example, a CAN (Controller Area Network).

[0024] The external device 54 is, for example, a vehicle control device. The vehicle control device controls various devices mounted on the vehicle. These devices include, for example, a drive source for driving, a braking system, and a steering system 2. When an automated driving system is installed in the vehicle, the vehicle control device comprehensively controls various in-vehicle systems. The automated driving system includes driver assistance systems such as ADAS (Advanced Driving Assistant System).

[0025] The drive circuit 52 is a PWM (Pulse Width Modulation) inverter in which three legs, each corresponding to one of the three phases (U-phase, V-phase, W-phase), are connected in parallel, with each leg being a basic unit consisting of two switching elements connected in series. The switching elements are, for example, FETs (Field Effect Transistors). The drive circuit 52 receives control signals S generated by the processing circuit 53. ｃ Based on this, the DC power supplied from the battery mounted on the vehicle is converted into three-phase AC power. The three-phase AC power is supplied to the motor 31 via power supply paths corresponding to each of the three phases.

[0026] The processing circuit 53 controls the steering torque T. ｈ The system calculates a target assist force based on the vehicle speed V, and calculates a current command value according to the calculated target assist force. The current command value is the target value of the current required for the motor 31 to generate the target assist force. The processing circuit 53 issues a control signal S to the drive circuit 52 by performing current feedback control. ｃ Generates.

[0027] Current feedback control is a control method that makes the value of the current actually supplied to the motor 31 follow the current command value. Control signal S ｃ This defines the duty cycle of each switching element in the drive circuit 52. Each switching element in the drive circuit 52 controls the control signal S ｃA switching operation is performed based on this. As a result, a current corresponding to the current command value is supplied to the motor 31. The motor 31 generates a rotational force corresponding to the target assist force.

[0028] <Configuration of the arithmetic circuit 51> Next, the configuration of the arithmetic circuit 51 will be described in detail. As shown in Figure 3, the arithmetic circuit 51 includes a relative angle calculation unit 60, a first straight-line driving learning unit 61, a second straight-line driving learning unit 62, a factory learning unit 63, a service learning unit 64, a steering angle midpoint arbitration unit 65, an absolute angle calculation unit 66, a storage medium 67, and a detection unit 68.

[0029] The storage medium 67 has a volatile memory area and a non-volatile memory area. The volatile memory area is an area of ​​the storage medium 67 that retains information only while power is supplied, and the information is erased when the power is cut off. The non-volatile memory area is an area of ​​the storage medium 67 that retains information even when the power is cut off. Both the volatile memory area and the non-volatile memory area are rewritable. Cutting off the power includes removing the battery and battery depletion. When the vehicle is equipped with a battery with a normal voltage, power is always supplied to the volatile memory area to retain information. That is, the volatile memory area retains information even when the vehicle power is turned off.

[0030] The relative angle calculation unit 60 calculates the rotation angle θ of the motor 31 detected by the rotation angle sensor 43. ｍ The rotation angle θ is captured and imported. ｍ Based on this, the relative rotation angle θ of the steering wheel 3 ｒ The relative angle calculation unit 60 has a turn counter function that counts the number of rotations of the motor 31. The relative angle calculation unit 60 uses the number of rotations of the motor 31 to calculate the rotation angle θ of the motor 31. ｍ The integral is calculated. The relative angle calculation unit 60 calculates the rotation angle θ. ｍ Based on the integrated value, the reduction ratio from the motor 31 to the steering wheel 3 is used to determine the relative rotation angle θ of the steering wheel 3. ｒ Perform the calculation.

[0031] The first straight-line driving learning unit 61 calculates the relative rotation angle θ of the steering wheel 3, which is calculated by the relative angle calculation unit 60. ｒ The first straight-line driving learning unit 61 incorporates the relative rotation angle θ of the steering wheel 3. ｒ Based on this, the midpoint of the first rudder angle θ ０１ Learn the data and obtain the learned value. The midpoint of the first rudder angle is θ. ０１ This is the steering angle θ when the steering wheel 3 is in the steering neutral position. ｓ The steering neutral position is the rotational position of the steering wheel 3 that corresponds to the vehicle's straight-ahead state.

[0032] When the first straight-line driving learning unit 61 satisfies the first learning condition, it determines the first steering angle midpoint θ according to the learning algorithm stored in the non-volatile memory area of ​​the storage medium 67. ０１ The calculation is performed. The first learning condition is also a condition for determining whether the vehicle is traveling in a straight line. The first learning condition includes, for example, the following conditions B1 to B4.

[0033] B1. The vehicle speed V exceeds the first vehicle speed threshold. B2. Relative rotation angle θ ｒ The amount of change is less than or equal to the first threshold amount. B3. Steering torque T ｈ The absolute value of must be less than or equal to the first steering torque threshold.

[0034] B4. The state in which all conditions B1 to B3 are met continues for a period exceeding the first time threshold. The first straight-line driving learning unit 61 calculates the first steering angle midpoint θ ０１ The first straight-line driving learning unit 61 stores the first steering angle midpoint θ as the latest learned value in the volatile memory area of ​​the storage medium 67. ０１ The first straight-line driving learning unit 61 calculates the first steering angle midpoint θ. ０１ Each time the calculation is performed, the first midpoint of the rudder angle θ stored in the volatile memory area of ​​the storage medium 67 ０１ Update the latest learned values.

[0035] The first straight-line driving learning unit 61 determines the first steering angle midpoint θ ０１The value of the first learning completion flag F1 is set depending on whether the learning is complete. The first straight-line driving learning unit 61 sets the value of the first steering angle midpoint θ ０１ When it is determined that the learning is not complete, the value of the first learning completion flag F1 is set to "0". The first straight-line driving learning unit 61 determines the first steering angle midpoint θ ０１ When it is determined that the learning process is complete, the value of the first learning completion flag F1 is set to "1".

[0036] The second straight-line driving learning unit 62 has basically the same configuration as the first straight-line driving learning unit 61. The second straight-line driving learning unit 62 controls the relative rotation angle θ of the steering wheel 3. ｒ Based on this, the midpoint of the second rudder angle θ ０２ Learn the data and obtain the learned value. The midpoint of the second rudder angle θ ０２ This is the steering angle θ when the steering wheel 3 is in the steering neutral position. ｓ That is the case.

[0037] When the second learning condition is met, the second straight-line driving learning unit 62 determines the second steering angle midpoint θ according to the learning algorithm stored in the non-volatile memory area of ​​the storage medium 67. ０２ The calculation is performed. The second learning condition is also a condition for determining whether the vehicle is traveling in a straight line. The second learning condition includes, for example, the following conditions C1 to C4.

[0038] C1. The vehicle speed V exceeds the second vehicle speed threshold. However, the second vehicle speed threshold may be the same as the first vehicle speed threshold. C2. Relative rotation angle θ ｒ The amount of change is less than or equal to the second threshold of change. However, the second threshold of change may be the same as the first threshold of change.

[0039] C3. Steering Torque T ｈ The absolute value of is less than or equal to the second steering torque threshold. However, the second steering torque threshold may be the same as the first steering torque threshold. C4. The state in which all conditions D to B3 are met continues for a period exceeding the second time threshold. However, the second time threshold is greater than the first time threshold.

[0040] The second straight-line driving learning unit 62 calculates the second steering angle midpoint θ ０２ The second straight-line driving learning unit 62 stores the latest learned value in the volatile memory area of ​​the storage medium 67. Each time the second learning condition is met, the second steering angle midpoint θ ０２ The second straight-line driving learning unit 62 calculates the second steering angle midpoint θ. ０２ Each time the calculation is performed, the second midpoint of the rudder angle θ stored in the volatile memory area of ​​the storage medium 67 ０２ Update the latest learned values.

[0041] The second straight-line driving learning unit 62 is the second steering angle midpoint θ ０２ Depending on whether the learning is complete, the value of the second learning completion flag F2 is set. The second straight-line driving learning unit 62 sets the second steering angle midpoint θ ０２ When it is determined that the learning is not complete, the value of the second learning completion flag F2 is set to "0". The second straight-line driving learning unit 62 sets the second steering angle midpoint θ ０２ When it is determined that the learning process is complete, the value of the second learning completion flag F2 is set to "1".

[0042] Furthermore, the second time threshold is greater than the first time threshold. That is, the learning time of the second straight-line driving learning unit 62 is longer than the learning time of the first straight-line driving learning unit 61. For this reason, the second steering angle midpoint θ ０２ The accuracy is the midpoint θ of the first rudder angle. ０１ This is higher than the accuracy of the first straight-line driving learning unit 61. However, since the learning time of the first straight-line driving learning unit 61 is shorter than the learning time of the second straight-line driving learning unit 62, the first steering angle midpoint θ ０１ Therefore, because the learning time is shorter, the second rudder angle midpoint θ ０２ It is calculated faster than that.

[0043] The factory learning unit 63 is used in a vehicle manufacturing plant when shipping a vehicle. The factory learning unit 63 determines, for example, the third steering angle midpoint θ based on a command from an external tool. ０３The system learns and obtains learned values. The external tool is, for example, a portable terminal carried by a worker assembling or maintaining a vehicle. The external tool can connect to the in-vehicle network. The external tool may also be a notebook personal computer.

[0044] When the factory learning unit 63 receives a command from an external tool, it determines the third midpoint of the rudder angle θ ０３ Learning begins. The processing circuit 53 controls the motor 31 based on commands from an external tool. The processing circuit 53 controls the motor 31 to move the steering shaft 22 to a first operating end, and then reverses it to a second operating end. The first operating end is the position where the first end of the steering shaft 22 abuts against the first end of the housing 23 that houses the steering shaft 22. The second operating end is the position where the second end of the steering shaft 22 abuts against the second end of the housing 23 that houses the steering shaft 22.

[0045] Furthermore, the midpoint θ of the third rudder angle ０３ When learning this, instead of controlling the motor 31, the operator may manually steer the steering wheel 3 to move the steering shaft 22 to the first operating end, and then reverse it to the second operating end.

[0046] The factory learning unit 63 uses the rotation angle θ of the motor 31 detected by the rotation angle sensor 43. ｍ The factory learning unit 63 incorporates the rotation angle θ of the motor 31 at the start and end of the reversal operation of the steering shaft 22. ｍ Based on this, the midpoint of the third rudder angle θ ０３ The calculation is performed. The midpoint θ of the third rudder angle. ０３ This is the steering angle θ when the steering wheel 4 is in the steering neutral position, that is, when the steering wheel 3 is in the steering neutral position. ｓ That is the case.

[0047] The factory learning unit 63 calculates the midpoint θ of the third rudder angle. ０３ This is stored as the initial learning value in the volatile memory area of ​​the storage medium 67. The initial learning value is the value of the steering angle midpoint that is learned for the first time before the vehicle is shipped. The factory learning unit 63 stores the third steering angle midpoint θ ０３Depending on whether the learning is complete, the value of the third learning completion flag F3 is set. The factory learning unit 63 sets the value of the third rudder angle midpoint θ ０３ When it is determined that the learning is not complete, the value of the third learning completion flag F3 is set to "0". The factory learning unit 63 determines the third rudder angle midpoint θ ０３ When it is determined that the learning process is complete, the value of the third learning completion flag F3 is set to "1".

[0048] The service learning unit 64 is used, for example, when performing vehicle maintenance at a vehicle sales company. For example, when the battery is removed from the vehicle for battery replacement, power is no longer supplied to the steering control device 1, and the steering angle midpoint stored in the volatile memory area of ​​the storage medium 67 is lost. Therefore, it is necessary to relearn the steering angle midpoint.

[0049] The service learning unit 64 performs the same processing as the factory learning unit 63. The service learning unit 64, for example, determines the fourth rudder angle midpoint θ based on a command from an external tool. ０４ The learning unit 64 learns and obtains learned values. When the service learning unit 64 receives a command from an external tool, it learns the fourth midpoint of the rudder angle θ ０４ The learning process begins. The processing circuit 53 controls the motor 31 based on commands from an external tool. The processing circuit 53 controls the motor 31 to move the steering shaft 22 to a first operating end, and then reverses it to a second operating end.

[0050] Furthermore, the midpoint θ of the fourth rudder angle ０４ When learning this, instead of controlling the motor 31, the operator may manually steer the steering wheel 3 to move the steering shaft 22 to the first operating end, and then reverse it to the second operating end.

[0051] The service learning unit 64 receives the rotation angle θ of the motor 31 detected by the rotation angle sensor 43. ｍ The service learning unit 64 incorporates the rotation angle θ of the motor 31 at the start and end of the reversal operation of the steering shaft 22. ｍ Based on this, the midpoint of the fourth rudder angle θ ０４ The calculation is performed. The midpoint θ of the fourth rudder angle. ０４is the steering angle θ when the steering wheel 4 is in the neutral position, that is, when the steering wheel 3 is in the neutral position. ｓ It is.

[0052] The service learning unit 64 stores the calculated fourth steering angle midpoint θ ０４ in the volatile memory area of the storage medium 67 as the initial learning value. The initial learning value is the value of the steering angle midpoint that is learned for the first time after the vehicle maintenance and the like are completed. The service learning unit 64 sets the value of the fourth learning completion flag F4 according to whether the learning of the fourth steering angle midpoint θ ０４ is completed. When it is determined that the learning of the fourth steering angle midpoint θ ０４ is not completed, the service learning unit 64 sets the value of the fourth learning completion flag F4 to "0". When it is determined that the learning of the fourth steering angle midpoint θ ０４ is completed, the service learning unit 64 sets the value of the fourth learning completion flag F4 to "1".

[0053] The steering angle midpoint arbitration unit 65 captures the first steering angle midpoint θ ０１ calculated by the first straight-ahead driving learning unit 61 and the second steering angle midpoint θ ０２ calculated by the second straight-ahead driving learning unit 62. Also, the steering angle midpoint arbitration unit 65 captures the third steering angle midpoint θ ０３ calculated by the factory learning unit 63 and the fourth steering angle midpoint θ ０４ calculated by the service learning unit 64. The steering angle midpoint arbitration unit 65 arbitrates the first steering angle midpoint θ ０１ and the second steering angle midpoint θ ０２ and the third steering angle midpoint θ ０３ and the fourth steering angle midpoint θ ０４ and performs arbitration.

[0054] The steering angle midpoint arbitration unit 65, for example, sets the third steering angle midpoint θ ０３ or the fourth steering angle midpoint θ ０４ as the initial value of the final steering angle midpoint θ ０ . Initial means, for example, after the vehicle starts to be used, the first steering angle midpoint θ ０１ and the second steering angle midpoint θ ０２This is the period until the learning process is complete. The midpoint of the final rudder angle is θ. ０ θ is the final midpoint of the steering angle used for steering device 2 or vehicle control. ０３ and the midpoint θ of the fourth rudder angle ０４ This is the initial learned value of the steering angle midpoint, learned by a learning process different from that of the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62.

[0055] The steering angle midpoint adjustment unit 65 adjusts the first steering angle midpoint θ by the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62. ０１ and the midpoint θ of the second rudder angle ０２ After the learning is complete, the first rudder angle midpoint θ ０１ or the midpoint θ of the second rudder angle ０２ The midpoint of the final rudder angle θ ０ The steering angle midpoint arbitration unit 65 sets the first steering angle midpoint θ by the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62. ０１ and the midpoint θ of the second rudder angle ０２ Each time it is learned, the latest first rudder angle midpoint θ ０１ or the midpoint θ of the second rudder angle ０２ The midpoint of the final rudder angle θ ０ It may also be set as follows. The steering angle midpoint arbitration unit 65 adjusts the set final steering angle midpoint θ ０ This is stored in the volatile memory area of ​​the storage medium 67.

[0056] The absolute angle calculation unit 66 calculates the relative rotation angle θ of the steering wheel 3, which is calculated by the steering angle calculation unit 60. ｒ The final steering angle midpoint θ is set by the steering angle midpoint adjustment unit 65. ０ The absolute angle calculation unit 66 calculates the relative rotation angle θ of the steering wheel 3. ｒ From the midpoint of the final steering angle θ ０ By subtracting this, the steering angle θ ｓ The calculation is performed using the absolute angle θ. ｓ This represents the net amount of steering input by the vehicle driver relative to the steering neutral position of the steering wheel 3.

[0057] The steering angle midpoint adjustment unit 65 has a determination unit 65A. The determination unit 65A determines the final steering angle midpoint θ ０The final midpoint of the rudder angle is determined by comparing it with the learned value of the midpoint of the rudder angle θ. ０ Determine whether there is a discrepancy between the learned value and the final rudder angle midpoint θ. ０ This is the current value of the midpoint of the steering angle used for controlling the steering device 2 or the vehicle. The learned value of the midpoint of the steering angle is the first midpoint of the steering angle θ learned by the first straight-line driving learning unit 61. ０１ The second steering angle midpoint θ is learned by the second straight-line driving learning unit 62. ０２ This includes.

[0058] The determination unit 65A determines the midpoint of the final rudder angle θ. ０ When the difference between the learned value of the midpoint of the rudder angle and the final midpoint of the rudder angle is less than or equal to the deviation threshold, the final midpoint of the rudder angle θ ０ The determination unit 65A determines that there is no discrepancy between the learned value of the final rudder angle midpoint θ. ０ When the difference between the learned value of the midpoint of the rudder angle exceeds the deviation threshold, the final midpoint of the rudder angle θ ０ It is determined that a discrepancy has occurred between the learned value of the midpoint of the rudder angle and the actual value.

[0059] The deviation is the midpoint θ of the final rudder angle. ０ The difference between the learned value and the midpoint of the rudder angle exceeds the acceptable range. The deviation judgment threshold is the midpoint of the final rudder angle θ. ０ This is a criterion for determining whether the difference between the learned value and the final rudder angle midpoint is within the acceptable range. The acceptable range is determined by product specifications, etc. Final rudder angle midpoint θ ０ The difference between this value and the learned value of the midpoint of the rudder angle is the final midpoint of the rudder angle θ ０ and the midpoint θ of the first rudder angle ０１ The difference from, and the midpoint of the final steering angle θ ０ and the midpoint θ of the second rudder angle ０２ This includes the difference.

[0060] The determination unit 65A determines whether a discrepancy has occurred between the final steering angle midpoint θ0 and the learned value of the steering angle midpoint, and then generates discrepancy information F. ｄ Generates divergence information F. ｄ This could be, for example, a flag. The determination unit 65A determines if there is no discrepancy between the final rudder angle midpoint θ0 and the learned value of the rudder angle midpoint, and then determines the discrepancy information F ｄThe value of is set to "0". The determination unit 65A determines that if a discrepancy occurs between the final steering angle midpoint θ0 and the learned value of the steering angle midpoint, it provides discrepancy information F ｄ The value of is set to "1". The determination unit 65A determines the deviation information F ｄ This is stored in the volatile memory area of ​​the storage medium 67.

[0061] The storage medium 67 contains deviation information F generated by the determination unit 65A. ｄ And, power status signal S ＩＧ It captures the power status signal S. ＩＧ This is an electrical signal indicating whether the vehicle's power supply is on or off, and is generated, for example, by the vehicle's start switch. Turning the vehicle's power supply on or off also involves turning on or off a start switch, for example, located in the driver's seat. The start switch is operated when starting or stopping the vehicle's drive source, and is, for example, an ignition switch or a power switch.

[0062] When the vehicle power is turned off, the storage medium 67 stores the discrepancy information F ｄ The data is moved from the volatile memory area of ​​the storage medium 67 to the non-volatile memory area. Therefore, even if the operating power supply to the storage medium 67 is cut off, the discrepancy information F ｄ It is possible to hold it.

[0063] Incidentally, the steering control device 1 has a power latch function. The power latch function is a function that maintains the operating power of the steering control device 1 for a predetermined period of time even when the start switch is turned off. Therefore, even after the start switch is turned off, the steering control device 1 can operate for a predetermined period of time.

[0064] The detection unit 68 performs anomaly detection processing. Among various anomalies, the anomaly detection processing particularly focuses on learning the midpoint of the rudder angle and the steering angle θ. ｓ This process detects anomalies that may affect the calculation. The anomalies include, for example, the following first to fourth anomalies D1 to D4.

[0065] D1. Abnormality of the storage medium 67. D2. Abnormality of the rotation angle sensor 43. D3. Battery removal / insertion, or abnormality of the turn counter function.

[0066] D4. During the period from when the vehicle power was last turned on until it was turned off, the midpoint of the final steering angle θ ０ A discrepancy occurred between the learned value and the midpoint of the steering angle. The detection unit 68 detects the power status signal S generated by the vehicle's start switch. ＩＧ The detection unit 68 captures the power status signal S. ＩＧ Based on this, the detection unit 68 determines whether the vehicle power supply has been turned on. If the detection unit 68 determines that the vehicle power supply has switched from off to on, it executes an abnormality detection process. Based on the result of the abnormality detection, the detection unit 68 issues an initialization signal S ｒ Generates the initialization signal S. ｒ This includes switching the on and off of the initialization signal S. ｒ This can also be a flag.

[0067] If none of the first to fourth abnormalities D1 to D4 are detected, the detection unit 68 will issue an initialization signal S ｒ Turn it off. Initialization signal S ｒ Turning this off means not requesting the first straight-line driving learning unit 61, the second straight-line driving learning unit 62, the factory learning unit 63, the service learning unit 64, and the steering angle midpoint arbitration unit 65 to initialize the steering angle midpoint stored in the volatile memory area of ​​the storage medium 67. The steering angle midpoint is the first to fourth steering angle midpoint θ ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ This includes.

[0068] If the detection unit 68 detects at least one of the first to fourth abnormalities D1 to D4, it will issue an initialization signal S ｒ Turn it on. Initialization signal S ｒ Turning this on means requesting the first straight-line driving learning unit 61, the second straight-line driving learning unit 62, the factory learning unit 63, the service learning unit 64, and the steering angle midpoint arbitration unit 65 to initialize the steering angle midpoints stored in the volatile memory area of ​​the storage medium 67. The steering angle midpoints are the first to fourth steering angle midpoints θ ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ This includes the initialization signal S. ｒThe process of switching from off to on is a process for initializing the midpoint of the rudder angle stored in the volatile memory area of ​​the storage medium 67.

[0069] The first straight-line driving learning unit 61 has a first initialization processing unit 61A. The second straight-line driving learning unit 62 has a second initialization processing unit 62A. The factory learning unit 63 has a third initialization processing unit 63A. The service learning unit 64 has a fourth initialization processing unit 64A. The steering angle midpoint arbitration unit 65 has a fifth initialization processing unit 65B.

[0070] The first to fifth initialization processing units 61A to 64A and 65B receive an initialization signal S from the detection unit 68. ｒ Receives initialization signal S. ｒ When this is ON, the first to fifth initialization processing units 61A to 64A and 65B execute initialization processing. Initialization processing is the process of initializing the rudder angle midpoints stored in the volatile memory area of ​​the storage medium 67. The rudder angle midpoints are the first to fourth rudder angle midpoints θ ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ This includes the following. Initialization includes erasing the midpoint of the rudder angle stored in the volatile memory of the storage medium 67.

[0071] However, the first to fifth initialization processing units 61A to 64A and 65B initialize the steering angle midpoint during the processing of the initial sequence. The initial sequence is a series of processes required for the steering system to operate. The initial sequence includes, for example, hardware checks, CPU initialization, and initialization of variables or flags. When the vehicle power is turned on, the steering control device 1 executes the initial sequence and then transitions to a state of normal control. Normal control is a control that generates assist force to the motor 31 according to the steering state of the steering wheel 3. By initializing the steering angle midpoint during the processing of the initial sequence, the steering angle θ is controlled. ｓ The impact of initialization on the external device 54 that uses this is suppressed.

[0072] If the steering angle midpoint disappears from the volatile memory area of ​​the storage medium 67 due to the execution of the initialization process, the steering angle midpoint arbitration unit 65 will learn the first steering angle midpoint θ as the vehicle is running. ０１ or the midpoint θ of the second rudder angle ０２ This is a new final steering angle midpoint θ used for steering device 2 or vehicle control. ０ The steering angle midpoint adjustment unit 65 is set to the newly set final steering angle midpoint θ. ０ This is stored in the volatile memory area of ​​the storage medium 67.

[0073] Note that the midpoints of the rudder angles that disappear from the volatile memory area due to the execution of the initialization process are the first to fourth midpoints of the rudder angles θ. ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ The midpoint of the rudder angle newly stored in the volatile memory area is the newly learned first midpoint of the rudder angle θ. ０１ And the newly learned second midpoint of the rudder angle θ ０２ And the newly set final rudder angle midpoint θ ０ And so it is.

[0074] <Configuration of Detection Unit 68> Next, the configuration of the detection unit 68 will be described in detail. As shown in Figure 4, the detection unit 68 has a first abnormality detection unit 71, a second abnormality detection unit 72, a third abnormality detection unit 73, and a fourth abnormality detection unit 74. When the vehicle power is turned on, the first to fourth abnormality detection units 71 to 74 perform abnormality detection processing according to a predetermined processing order. The processing order is set in order of the shortest calculation cycle. For example, the processing order is the first abnormality detection unit 71, the second abnormality detection unit 72, the third abnormality detection unit 73, and the fourth abnormality detection unit 74.

[0075] The first abnormality detection unit 71 immediately detects the first abnormality D1 when the vehicle power is turned on. The first abnormality D1 is an abnormality of the storage medium 67. If the first abnormality D1 is not detected, the first abnormality detection unit 71 sets the value of the first abnormality judgment flag FG1 to "0". If the first abnormality D1 is detected, the first abnormality detection unit 71 sets the value of the first abnormality judgment flag FG1 to "1".

[0076] Furthermore, if the detection process for the first abnormality D1 has not been completed, the first abnormality detection unit 71 sets the value of the first abnormality detection completion flag FG11 to "0". If the detection process for the first abnormality D1 has been completed, the first abnormality detection unit 71 sets the value of the first abnormality detection completion flag FG11 to "1".

[0077] The second abnormality detection unit 72 determines whether the initialization process of the first initialization processing unit 61A has been completed based on the value of the first abnormality detection completion flag F11. When the abnormality detection process of the first abnormality detection unit 71 is completed, the second abnormality detection unit 72 detects a second abnormality D2. The second abnormality D2 is an abnormality of the rotation angle sensor 43. If the second abnormality D2 is not detected, the second abnormality detection unit 72 sets the value of the second abnormality judgment flag FG2 to "0". If the second abnormality D2 is detected, the second abnormality detection unit 72 sets the value of the second abnormality judgment flag FG2 to "1".

[0078] Furthermore, if the detection process for the second abnormality D2 has not been completed, the second abnormality detection unit 72 sets the value of the second abnormality detection completion flag FG12 to "0". If the detection process for the second abnormality D2 has been completed, the second abnormality detection unit 72 sets the value of the second abnormality detection completion flag FG12 to "1".

[0079] The third abnormality detection unit 73 determines whether the abnormality detection process of the first abnormality detection unit 71 and the abnormality detection process of the second abnormality detection unit 72 have been completed, based on the value of the first abnormality detection completion flag FG11 and the value of the second abnormality detection completion flag FG12. If the abnormality detection process of the first abnormality detection unit 71 and the abnormality detection process of the second abnormality detection unit 72 have been completed, the third abnormality detection unit 73 detects a third abnormality D3. The third abnormality is either battery removal / installation or an abnormality in the turn counter function. If the third abnormality D3 is not detected, the third abnormality detection unit 73 sets the value of the third abnormality determination flag FG3 to "0". If a third abnormality is detected, the third abnormality detection unit 73 sets the value of the third abnormality determination flag FG3 to "1".

[0080] Furthermore, if the detection process for the third abnormality D3 has not been completed, the third abnormality detection unit 73 sets the value of the third abnormality detection completion flag FG13 to "0". If the detection process for the third abnormality D3 has been completed, the third abnormality detection unit 73 sets the value of the third abnormality detection completion flag FG13 to "1".

[0081] The fourth abnormality detection unit 74 determines whether the abnormality detection processing of the first to third abnormality detection units 71 to 73 has been completed, based on the values ​​of the first to third abnormality detection completion flags FG11 to FG13. When the abnormality detection processing of the first to third abnormality detection units 71 to 73 is completed, the fourth abnormality detection unit 74 detects the fourth abnormality D4. The fourth abnormality D4 is the midpoint of the final steering angle θ during the period from when the vehicle power was last turned on until it was turned off. ０ This is a discrepancy that occurs between the learned value of the midpoint of the rudder angle and the learned value of the first midpoint of the rudder angle θ. ０１ and the midpoint θ of the second rudder angle ０２ This includes the following. The fourth abnormality detection unit 74 determines that the vehicle power is on, and the deviation information F stored in the non-volatile memory area of ​​the storage medium 67 ｄ The divergence information F that is taken in is incorporated. ｄ Based on this, the fourth anomaly D4 is determined.

[0082] The fourth anomaly detection unit 74 detects deviation information F ｄ If the value is "0", the value of the fourth abnormality judgment flag FG4 is set to "0". Deviation information F ｄ A value of "0" means that the final steering angle midpoint θ occurred during the period from when the vehicle power was last turned on until when it was turned off. ０ This indicates that there is no discrepancy between the learned value and the midpoint of the rudder angle.

[0083] The fourth anomaly detection unit 74 detects deviation information F ｄ If the value is "1", the value of the fourth abnormality judgment flag FG4 is set to "1". Deviation information F ｄ A value of "1" means that the midpoint of the final steering angle θ during the period from when the vehicle power was last turned on until when it was turned off. ０ This indicates that a discrepancy has occurred between the learned value and the midpoint of the rudder angle.

[0084] The fourth abnormality detection unit 74 initializes the first to fourth abnormality determination flags FG1 to FG4 based on the values ​​of the initialization signal S ｒ Generates the initialization signal S. ｒ This includes switching the on and off. The fourth abnormality detection unit 74 will signal an initialization signal S if all values ​​of the first to fourth abnormality determination flags FG1 to FG4 are "0". ｒ The fourth abnormality detection unit 74 turns off the initialization signal S if at least one of the first to fourth abnormality determination flags FG1 to FG4 is "1", that is, if at least one of the first to fourth abnormalities D1 to D4 has occurred. ｒ Turn it on.

[0085] <Initialization Process Order> Next, the initialization process order by the first to fifth initialization processing units 61A to 64A and 65B will be explained.

[0086] As shown in Figure 3, the first to fifth initialization processing units 61A to 64A and 65B receive an initialization signal S from the detection unit 68. ｒ Receives initialization signal S. ｒ When this is ON, the first to fifth initialization processing units 61A to 64A and 65B execute initialization processing. However, the first to fifth initialization processing units 61A to 64A and 65B may execute initialization processing according to a predetermined processing order. For example, the processing order is the first initialization processing unit 61A, the second initialization processing unit 62A, the third initialization processing unit 63A, the fourth initialization processing unit 64A, and the fifth initialization processing unit 65B.

[0087] Initialization signal S ｒ When this is ON, the first initialization processing unit 61A determines the first midpoint of the rudder angle θ ０１ The first initialization processing unit 61A initializes the first rudder angle midpoint θ. ０１ If initialization is not complete, the value of the first initialization completion flag F11 is set to "0". The first initialization processing unit 61A sets the first rudder angle midpoint θ ０１ Once the initialization is complete, the value of the first initialization completion flag F11 is set to "1".

[0088] Initialization signal S ｒIf this is ON, the second initialization processing unit 62A will, after the initialization processing of the first initialization processing unit 61A is completed, determine the second rudder angle midpoint θ ０２ The first initialization processing unit 61A initializes the first initialization processing unit 62A determines whether the initialization process of the first initialization processing unit 61A has been completed based on the value of the first initialization completion flag F11. The second initialization processing unit 62A determines the second rudder angle midpoint θ ０２ If the initialization is not complete, the value of the second initialization completion flag F12 is set to "0". The second initialization processing unit 62A sets the second rudder angle midpoint θ ０２ Once the initialization is complete, the value of the second initialization completion flag F12 is set to "1".

[0089] Initialization signal S ｒ If this is ON, the third initialization processing unit 63A will, after the initialization processing of the second initialization processing unit 62A is completed, determine the third rudder angle midpoint θ ０３ The third initialization processing unit 63A initializes the third rudder angle midpoint θ. Based on the value of the second initialization completion flag F12, the third initialization processing unit 63A determines whether the initialization process of the second initialization processing unit 62A has been completed. The third initialization processing unit 63A initializes the third rudder angle midpoint θ. ０３ If the initialization is not complete, the value of the third initialization completion flag F13 is set to "0". The third initialization processing unit 63A sets the third rudder angle midpoint θ ０３ Once the initialization is complete, the value of the third initialization completion flag F13 is set to "1".

[0090] Initialization signal S ｒ If this is ON, the fourth initialization processing unit 64A will, after the initialization processing of the third initialization processing unit 63A is completed, determine the fourth rudder angle midpoint θ ０４ The fourth initialization processing unit 64A initializes the fourth rudder angle midpoint θ. Based on the value of the third initialization completion flag F13, the fourth initialization processing unit 64A determines whether the initialization process of the third initialization processing unit 63A has been completed. ０４ If the initialization is not complete, the value of the fourth initialization completion flag F14 is set to "0". The fourth initialization processing unit 64A sets the fourth rudder angle midpoint θ ０４ Once the initialization is complete, the value of the fourth initialization completion flag F14 is set to "1".

[0091] Initialization signal S ｒ If this is ON, the fifth initialization processing unit 65B will, after the initialization processing of the fourth initialization processing unit 64A is completed, determine the final rudder angle midpoint θ ０ The fifth initialization processing unit 65B initializes the fourth initialization processing unit 64A based on the value of the fourth initialization completion flag F14. The fifth initialization processing unit 65B determines the final rudder angle midpoint θ ０ If initialization is not complete, the value of the fifth initialization completion flag F15 is set to "0". The fifth initialization processing unit 65B determines the final rudder angle midpoint θ ０ Once the initialization is complete, the value of the fifth initialization completion flag F15 is set to "1".

[0092] The absolute angle calculation unit 66 receives the value of the fifth initialization completion flag F15. The absolute angle calculation unit 66 generates initialization completion information F16 according to the value of the fifth initialization completion flag F15. Initialization completion information F16 is information indicating that a series of initialization processes by the first to fifth initialization processing units 61A to 64A and 65B have been completed. Initialization completion information F16 may be a flag. The absolute angle calculation unit 66 turns off initialization completion information F16 when the value of the fifth initialization completion flag F15 is "0". The absolute angle calculation unit 66 turns on initialization completion information F16 when the value of the fifth initialization completion flag F15 is "1".

[0093] As shown in Figure 2, the processing circuit 53 and the external device 54 receive initialization completion information F16. Based on the initialization completion information F16, the processing circuit 53 and the external device 54 determine whether a series of initialization processes have been performed by the first to fifth initialization processing units 61A to 64A and 65B.

[0094] If the initialization completion information F16 is off, the processing circuit 53 and the external device 54 determine that the series of initialization processes by the first to fifth initialization processing units 61A to 64A and 65B have not been performed, and the steering angle θ calculated by the calculation circuit 51 is determined. ｓ Continue using it.

[0095] When the initialization completion information F16 is ON, the processing circuit 53 and the external device 54 determine that a series of initialization processes have been performed by the first to fifth initialization processing units 61A to 64A and 65B, and execute the predetermined process. This process involves, for example, the steering angle θ calculated by the arithmetic circuit 51. ｓ The use of the device is discontinued, and the processing circuit 53 and external device 54 automatically adjust the steering angle θ. ｓ This includes the process of performing calculations.

[0096] <Effects of this embodiment> This embodiment provides the following effects: (1) The steering control device 1 controls the vehicle's steering device 2 using the midpoint of the steering angle of the steering wheel 3. The steering control device 1 comprises a learning unit, an absolute angle calculation unit 66, and a detection unit 68. The first straight-line driving learning unit 61 and the second straight-line driving learning unit 62 correspond to the learning unit. The learning unit learns the midpoint of the steering angle of the steering wheel 3 when the vehicle is driving in a straight line and obtains a learned value. The absolute angle calculation unit 66 calculates the steering angle θ of the steering wheel 3 based on the current value of the midpoint of the steering angle. ｓ The absolute steering angle is used in the calculation, and the calculated steering angle θ is calculated. ｓ This is transmitted to an external device 54 mounted on the vehicle.

[0097] When the vehicle power is turned on, the detection unit 68 learns the midpoint of the steering angle and the steering angle θ. ｓ The system detects anomalies that affect the calculation, and if an anomaly is detected, it performs a process to initialize the current value and learned value of the midpoint of the rudder angle. Final midpoint of rudder angle θ ０ This corresponds to the current value of the midpoint of the rudder angle. The first midpoint of the rudder angle θ ０１ and the midpoint θ of the second rudder angle ０２ This corresponds to the learned value of the midpoint of the rudder angle. The process of initializing the current value and the learned value of the midpoint of the rudder angle is, for example, performed by the initialization signal S. ｒ This is the process of turning it on.

[0098] The absolute angle calculation unit 66 transmits an electrical signal to the external device 54 when it has completed the process of initializing the current value and learned value of the steering angle midpoint. The electrical signal is, for example, initialization completion information F16. With this configuration, if an abnormality occurs after the vehicle power is turned on, such as the steering angle midpoint being initialized, an electrical signal indicating this is transmitted to the external device 54. As a result, the external device 54 may receive an incorrect steering angle midpoint or steering angle θ. ｓ It is possible to suppress the execution of control based on this.

[0099] (2) The detection unit 68 detects multiple different abnormalities in a predetermined order, and after the process of detecting all abnormalities is completed, it executes a process to initialize the current value and learned value of the midpoint of the rudder angle. The abnormalities include, for example, the first to fourth abnormalities D1 to D4 described above. With this configuration, it is possible to suppress the execution of the process of initializing the current value and learned value of the midpoint of the rudder angle each time an abnormality is detected. Furthermore, even if multiple abnormalities are detected at different timings, the process of initializing the current value and learned value of the midpoint of the rudder angle is executed only once. As a result, the number of times the storage medium 67 is accessed in conjunction with the occurrence of an abnormality, i.e., the number of times the storage medium 67 is rewritten, can be reduced.

[0100] (3) The detection unit 68 detects abnormalities in order of the shortest calculation cycle for detecting abnormalities. The calculation cycles become shorter in the order of, for example, the first abnormality detection unit 71, the second abnormality detection unit 72, the third abnormality detection unit 73, and the fourth abnormality detection unit 74. With this configuration, multiple abnormalities can be detected smoothly.

[0101] (4) The rudder angle midpoint arbitration unit 65 corresponds to the arbitration unit. After the detection unit 68 performs a process to initialize the current value and the learned value of the rudder angle midpoint, the arbitration unit sets the learned value of the rudder angle midpoint learned by the learning unit as the new current value of the rudder angle midpoint used to control the steering device 2. With this configuration, after the detection unit performs a process to initialize the current value and the learned value of the rudder angle midpoint, the learned value of the rudder angle midpoint learned by the learning unit is set as the new current value of the rudder angle midpoint used to control the steering device. Therefore, it is possible to suppress the continuation of the state in which the value of the rudder angle midpoint is initialized. Initialization includes, for example, erasing the value of the rudder angle midpoint.

[0102] (5) The steering angle midpoint arbitration unit 65 corresponds to the arbitration unit. The arbitration unit sets the initial learned value of the steering angle midpoint, obtained by a learning process different from that of the learning unit, as the initial value of the steering angle midpoint used for controlling the steering device 2. The first straight-line driving learning unit 61 and the second straight-line driving learning unit 62 correspond to the learning unit. The third steering angle midpoint θ is learned by the factory learning unit 63. ０３ The fourth midpoint θ of the rudder angle is learned by the service learning unit 64. ０４ This corresponds to the initial learned value of the steering angle midpoint obtained by different learning processes for the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62. With this configuration, the steering system can be controlled using the initial learned value of the steering angle midpoint before the learning unit completes its learning of the vehicle when driving straight.

[0103] <Other Embodiments> This embodiment may be implemented with the following modifications: - The storage medium 67 stores deviation information F when the vehicle power is turned off. ｄ In addition, the current value and learned value of the midpoint of the rudder angle may also be moved from the volatile memory area to the non-volatile memory area. The current value of the midpoint of the rudder angle is the final midpoint of the rudder angle θ ０ The learned values ​​for the midpoint of the rudder angle are the midpoints θ of the first to fourth rudder angles. ０１ ~θ ０４ This way, the current value and learned value of the midpoint of the rudder angle can be retained, for example, even after the battery has been replaced.

[0104] - The steering control device 1 may be configured in which one of the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62 is omitted. Alternatively, the steering control device 1 may be configured in which at least one of the factory learning unit 63 and the service learning unit 64 is omitted. However, in this specification, "at least one of A and B" means "A only, B only, or both A and B".

[0105] The motor 31 may be mounted on the steering shaft 20. The motor 31 is connected to the steering shaft 20 via a reduction gear 34. The reduction gear 34 is, for example, a worm gear reduction gear. The reduction gear 34 reduces the rotation of the motor 31 and transmits the reduced rotation to the steering shaft 20. The reduction gear 34 is positioned on the portion of the steering shaft 20 opposite to the steering wheel 3 with respect to the torque sensor 42.

[0106] - The calculation circuit 51 and the processing circuit 53 may be integrated to constitute a single circuit. - The steering control device 1 may be applied to a steer-by-wire type steering system having a steering mechanism and a steering mechanism. Power transmission between the steering mechanism and the steering mechanism is separated. The steering mechanism is a mechanism part that is steered by the driver via the steering wheel 3 and has a reaction motor. The reaction motor generates a steering reaction force to be applied to the steering shaft 20. The steering mechanism is a mechanism part that steers the steering wheels 4 of the vehicle in response to the steering of the steering wheel 3 and has a steering motor. The steering motor generates a steering force to steer the steering wheels of the vehicle. The steering control device 1 controls the reaction motor and the steering motor.

Claims

1. A steering control device configured to control the steering system of a vehicle using the steering angle midpoint of a steering wheel, comprising: a learning unit configured to learn the steering angle midpoint and obtain a learned value when the vehicle is moving straight; an absolute angle calculation unit configured to calculate the steering angle of the steering wheel as an absolute steering angle based on the current value of the steering angle midpoint and to transmit the calculated steering angle to an external device mounted on the vehicle; and a detection unit configured to detect an abnormality that affects the learning of the steering angle midpoint and the calculation of the steering angle when the vehicle power is turned on, and to perform a process to initialize the current value and the learned value of the steering angle midpoint when an abnormality is detected, wherein the absolute angle calculation unit is configured to transmit an electrical signal to the external device indicating that the process of initializing the current value and the learned value of the steering angle midpoint has been completed.

2. The steering control device according to claim 1, wherein the detection unit is configured to detect a plurality of different abnormalities in a predetermined order, and after the process of detecting all the abnormalities is completed, it executes a process of initializing the current value and the learned value of the midpoint of the rudder angle.

3. The steering control device according to claim 2, wherein the detection unit is configured to detect abnormalities in order of the shortest calculation period for detecting the abnormality.

4. The steering control device according to any one of claims 1 to 3, further comprising an arbitration unit configured to set the learned value of the rudder angle midpoint as a new current value of the rudder angle midpoint used for controlling the steering device, after the detection unit has performed a process to initialize the current value and learned value of the rudder angle midpoint.

5. The steering control device according to any one of claims 1 to 3, further comprising an arbitration unit configured to set the initial learned value of the midpoint of the rudder angle, obtained by a learning process different from that of the learning unit, as the initial value of the midpoint of the rudder angle used for controlling the steering device.

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