Steering control device

Abstract

This steering control device (1) comprises learning units (61, 62), an arbitration unit (65), and a detection unit (68). The learning units learn the steering angle midpoint of a steering wheel (3) to obtain learned values. The arbitration unit determines whether there is a deviation between the current value of the steering angle midpoint (θ0) and the learned values (θ01, θ02). When the vehicle power supply is turned on, the detection unit detects, on the basis of the determination result of the arbitration unit, whether a deviation has occurred between the current value of the steering angle midpoint and the learned values during a period from the last time the vehicle power supply was turned on until the vehicle power supply was turned off. The detection unit executes processing for initializing the current value and the learned values of the steering angle midpoint when the vehicle power supply is turned on and the determination result (Fd) of the arbitration unit indicates the occurrence of a deviation between the current value and the learned values of the steering angle midpoint.

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 system of a vehicle. When the vehicle is traveling in a straight line, the steering control device learns the steering angle midpoint. The steering angle midpoint is the steering angle that indicates the steering neutral position of the steering wheel, and serves as the reference for calculating the steering angle in absolute angle. The steering control device sequentially updates the old steering angle midpoint with the newly learned steering angle midpoint. This makes it possible to appropriately control the steering system using a highly accurate steering angle midpoint.

[0003] Japanese Patent Publication No. 2010-36868

[0004] The steering control system is required to prevent the steering angle midpoint from disappearing, even temporarily, while the vehicle is in motion.

[0005] 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 arbitration 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 arbitration unit is configured to determine whether a discrepancy has occurred between the current value of the steering angle midpoint and the learned value of the steering angle midpoint. The detection unit is configured to detect, when the vehicle power is turned on, whether the discrepancy occurred during the period from when the vehicle power was last turned on until when it was turned off, based on the determination result of the arbitration unit. When the vehicle power is turned on, the detection unit is configured to perform a process to initialize the current value and the learned value of the steering angle midpoint if the determination result of the arbitration unit indicates the occurrence of the discrepancy.

[0006] 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 deviation detection process performed by the detection unit of Figure 3.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] When the steering shaft 22 moves axially, the steering angle θ of the steering wheel 4 changes. ｗThis 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.

[0012] 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:

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] The torque sensor 42 is provided on the steering shaft 20. The torque sensor 42 detects the steering torque T applied to the steering shaft 20. ｈ The steering torque T ｈ is calculated based on the amount of torsion of a torsion bar 42a provided on the steering shaft 20. The steering torque T ｈ is a state variable that reflects the steering state of the steering wheel 3.

[0018] The rotation angle sensor 43 is provided on the motor 31. The rotation angle sensor 43 detects the rotation angle θ of the motor 31. ｍ The rotation angle θ ｍ is a relative angle and is in 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). [[ID=1,5]]

[0019] 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 controls the operation of the motor 31 using, for example, the vehicle speed V detected by the vehicle speed sensor 4, 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 [[ID=,20]]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.

[0020] The steering control device 1 uses the steering angle θ of the steering wheel 3 ｓ 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.

[0021] <Configuration of the Steering Control Device> Next, the configuration of the steering control device 1 will be described in detail. As shown in Figure 2, the steering control device 1 has an arithmetic circuit 51, a drive circuit 52, and a processing circuit 53.

[0022] The calculation circuit 51 calculates the rotation angle θ of the motor 31 detected by the rotation angle sensor 43. ｍ The calculation circuit 51 takes in the rotation angle θ of the motor 31. ｍ Using the steering angle θ ｓ The steering angle θ is calculated. ｓ This is an absolute angle and can exceed 360°. The calculation circuit 51 receives the steering angle θ via the in-vehicle network. ｓ The data may also be transmitted to an external device 54. The in-vehicle network is, for example, a CAN (Controller Area Network).

[0023] 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).

[0024] 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.

[0025] The processing circuit 53 controls the steering torque T. ｈThe 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.

[0026] 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 ｃ A 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.

[0027] <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.

[0028] 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.

[0029] 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.

[0030] 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 θ of the first rudder angle 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.

[0031] 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.

[0032] 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.

[0033] 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 ０１The latest learned value is stored in the volatile memory area of ​​the storage medium 67. The first straight-line driving learning unit 61 stores the first steering angle midpoint θ each time the first learning condition is met. 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.

[0034] The first straight-line driving learning unit 61 determines the first steering angle midpoint θ ０１ The 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".

[0035] 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.

[0036] 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.

[0037] 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 ｒThe 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.

[0038] 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.

[0039] 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 second steering angle midpoint θ as the latest learned value in the volatile memory area of ​​the storage medium 67. 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.

[0040] 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 determines 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".

[0041] 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 θ０１ Therefore, because the learning time is shorter, the second rudder angle midpoint θ ０２ It is calculated faster than that.

[0042] 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. ０３ The 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The factory learning unit 63 calculates the midpoint θ of the third rudder angle. ０３ The value is stored 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 before the vehicle is shipped. The factory learning unit 63 stores the third steering angle midpoint θ ０３ Depending 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".

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The learning unit 64 for service captures the rotation angle θ of the motor 31 detected by the rotation angle sensor 43. ｍ The learning unit 64 for service calculates a fourth rudder angle midpoint θ based on the rotation angle θ of the motor 31 at the start point and the end point of the reverse operation of the steering shaft 22. ｍ ０４ The fourth rudder angle midpoint θ is the steering angle θ when the steering wheel 4 is at the steering neutral position, that is, when the steering wheel 3 is at the steering neutral position. ｓ

[0051] The learning unit 64 for service stores the calculated fourth rudder angle midpoint θ as an initial learning value in the volatile memory area of the storage medium 67. The initial learning value is the value of the rudder angle midpoint that is learned for the first time after the vehicle maintenance and the like are completed. The learning unit 64 for service sets the value of the fourth learning completion flag F4 according to whether the learning of the fourth rudder angle midpoint θ is completed. When it is determined that the learning of the fourth rudder angle midpoint θ is not completed, the learning unit 64 for service sets the value of the fourth learning completion flag F4 to "0". When it is determined that the learning of the fourth rudder angle midpoint θ is completed, the learning unit 64 for service sets the value of the fourth learning completion flag F4 to "1". ０４ ０４ ０４ ０４

[0052] The rudder angle midpoint arbitration unit 65 captures the first rudder angle midpoint θ calculated by the first straight-ahead driving learning unit 61 and the second rudder angle midpoint θ calculated by the second straight-ahead driving learning unit 62. Also, the rudder angle midpoint arbitration unit 65 captures the third rudder angle midpoint θ calculated by the learning unit 63 for factory and the fourth rudder angle midpoint θ calculated by the learning unit 64 for service. The rudder angle midpoint arbitration unit 65 arbitrates the first rudder angle midpoint θ, the second rudder angle midpoint θ, the third rudder angle midpoint θ, and the fourth rudder angle midpoint θ. ０１ ０２ ０３ ０４ ０１ ０２ ０３ ０４

[0053] ​​​​​​​​​​​​​​​​The rudder angle midpoint adjustment unit 65 sets, for example, the third rudder angle midpoint θ ０３ or the fourth rudder angle midpoint θ ０４ as the initial value of the final rudder angle midpoint θ ０ . "Initial" means, for example, the period from the start of vehicle use until the learning of the first rudder angle midpoint θ ０１ and the second rudder angle midpoint θ ０２ by the first straight - running learning unit 61 and the second straight - running learning unit 62 is completed. The final rudder angle midpoint θ ０ is the final rudder angle midpoint used for controlling the steering device 2 or the vehicle. The third rudder angle midpoint θ ０３ and the fourth rudder angle midpoint θ ０４ are the initial learning values of the rudder angle midpoints obtained by a learning process different from that of the first straight - running learning unit 61 and the second straight - running learning unit 62.

[0054] After the learning of the first rudder angle midpoint θ ０１ and the second rudder angle midpoint θ ０２ by the first straight - running learning unit 61 and the second straight - running learning unit 62 is completed, the rudder angle midpoint adjustment unit 65 sets the first rudder angle midpoint θ ０１ or the second rudder angle midpoint θ ０２ as the final rudder angle midpoint θ ０ . The rudder angle midpoint adjustment unit 65 may set the latest first rudder angle midpoint θ ０１ or the second rudder angle midpoint θ ０２ as the final rudder angle midpoint θ ０１ or the second rudder angle midpoint θ ０２ as the final rudder angle midpoint θ ０ each time the first rudder angle midpoint θ ０１ and the second rudder angle midpoint θ ０２ are learned. The rudder angle midpoint adjustment unit 65 stores the set final rudder angle midpoint θ ０ in the volatile memory area of the storage medium 67.

[0055] The absolute angle calculation unit 66 takes in the relative rotation angle θ ｒ of the steering wheel 3 calculated by the steering angle calculation unit 60 and the final rudder angle midpoint θ ０ set by the rudder angle midpoint adjustment unit 65. The absolute angle calculation unit 66 calculates from the relative rotation angle θ ｒ of the steering wheel 3 to the final rudder angle midpoint θ ０By 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.

[0056] The steering angle midpoint adjustment unit 65 has a determination unit 65A. The determination unit 65A determines the final steering angle midpoint θ ０ The 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.

[0057] 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.

[0058] 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.

[0059] 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 ｄ The 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] The detection unit 68 performs deviation detection processing. The deviation detection processing is performed during the period from when the vehicle power was last turned on until when it was turned off, determining the midpoint of the final steering angle θ ０ This process detects whether a discrepancy has occurred between the learned value of the rudder angle midpoint and the learned value of the first rudder angle midpoint θ. ０１ and the midpoint θ of the second rudder angle ０２ This includes.

[0064] 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 system determines whether the vehicle power supply is on or off. If the detection unit 68 determines that the vehicle power supply has switched from off to on, it retrieves the discrepancy information F stored in the non-volatile memory area of ​​the storage medium 67. ｄ The detection unit 68 takes in the deviation information F. ｄ Based on this, 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.

[0065] 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. ｒ The 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.

[0066] 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 θ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ This includes.

[0067] The detection unit 68 detects the deviation information F ｄ If the value is "0", the initialization signal S ｒ Turn it off. Discrepancy 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. The detection unit 68 receives discrepancy information F ｄ If the value is "1", the initialization signal S ｒ Turn it on. Discrepancy 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] <Procedure for deviation detection processing by detection unit 68> Next, the procedure for deviation detection processing by detection unit 68 will be described. As shown in Figure 4, when the vehicle power is turned on, the detection unit 68 determines whether the deviation detection process has not been processed (step S101). The detection unit 68 determines whether the deviation detection process has not been processed based on, for example, the processing completion flag. If the deviation detection process has not been completed, the detection unit 68 sets the value of the processing completion flag to "0". If the deviation detection process has been completed, the detection unit 68 sets the value of the processing completion flag to "1".

[0074] If the deviation detection process has not been processed (YES in step S101), the detection unit 68 will process the deviation information F ｄ Based on this, it is determined whether there is a discrepancy (step S102). The discrepancy is 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 is the discrepancy between the learned value and the midpoint of the rudder angle.

[0075] If the detection unit 68 determines that there is a discrepancy (YES in step S102), that is, if the discrepancy information F ｄ If the value is "1", it is determined whether the initialization of the rudder angle midpoint has not been performed (step S103). The detection unit 68 determines whether the initialization of the rudder angle midpoint has not been performed, for example, based on whether the initialization determination condition is met. The rudder angle midpoint is the first to fourth rudder angle midpoint θ ０１ ~θ ０４ And the midpoint of the final steering angle θ ０ This includes.

[0076] The initialization determination conditions include, for example, the following two conditions D1 and D2. The detection unit 68 determines that the initialization of the rudder angle midpoint has not been performed if the initialization determination conditions are met, that is, if both conditions D1 and D2 are satisfied. The detection unit 68 determines that the initialization of the rudder angle midpoint has been performed if the initialization determination conditions are not met, that is, if at least one of the two conditions D1 and D2 is not satisfied.

[0077] D1. Learning by the first straight-line driving learning unit 61, the second straight-line driving learning unit 62, the factory learning unit 63, and the service learning unit 64 is incomplete. D2. The values ​​of the first to fourth learning completion flags F1 to F4 are all "0".

[0078] If the initialization of the midpoint of the rudder angle has not been performed (YES in step S103), the detection unit 68 will detect the initialization signal S ｒ The value is set to "1" (step S104). At this point, the detection unit 68 determines that the deviation detection process is complete, sets the value of the processing completion flag to "1", and terminates the process.

[0079] Furthermore, if it is determined in step S103 that the initialization of the midpoint of the rudder angle has been completed (NO in step S103), and if it is determined in step S102 that there is no discrepancy (NO in step S102), the detection unit 68 will receive the initialization signal S ｒ The value is set to "0" (step S105). At this point, the detection unit 68 determines that the deviation detection process is complete, sets the value of the processing completion flag to "1", and terminates the process.

[0080] Furthermore, if it is determined in step S101 that the deviation detection process is not incomplete (NO in step S101), that is, if it is determined that the deviation detection process is complete, the detection unit 68 terminates the process.

[0081] <Effects of this embodiment> This embodiment provides the following effects: (1) The steering control device controls the vehicle's steering device 2 using the steering angle midpoint of the steering wheel. The steering control device 1 comprises a learning unit, an arbitration unit, 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 steering angle midpoint of the steering wheel 3 when the vehicle is driving straight and obtains a learned value. The steering angle midpoint arbitration unit 65 corresponds to the arbitration unit. The arbitration unit determines whether a discrepancy occurs between the current value of the steering angle midpoint and the learned value of the steering angle midpoint. Final steering angle midpoint 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.

[0082] When the vehicle power is turned on, the detection unit 68 detects, based on the determination result of the arbitration unit, whether a discrepancy has occurred between the current value and the learned value of the steering angle midpoint during the period from when the vehicle power was last turned on until when it was turned off. When the vehicle power is turned on, if the determination result of the arbitration unit indicates that a discrepancy has occurred between the current value and the learned value of the steering angle midpoint, the detection unit 68 executes a process to initialize the current value and the learned value of the steering angle midpoint. The process of initializing the current value and the learned value of the steering angle midpoint is, for example, performed by an initialization signal S ｒ This is the process of turning it on.

[0083] In this configuration, the process of initializing the current value and learned value of the steering angle midpoint is executed when the vehicle power is turned on. In other words, the process of initializing the steering angle midpoint is not performed while the vehicle is in motion. Therefore, for example, the loss of the steering angle midpoint while the vehicle is in motion is suppressed. Unlike the case where the process of initializing the current value and learned value of the steering angle midpoint is executed immediately when a discrepancy occurs between the current value and learned value of the steering angle midpoint while the vehicle is in motion, the steering angle midpoint will not be lost while the vehicle is in motion. Therefore, the impact on the control of the steering device 2 can be reduced. In addition, the steering of the steering wheel 3 can be appropriately assisted.

[0084] (2) The steering control device 1 further includes a non-volatile memory unit. The non-volatile memory area of ​​the storage medium 67 corresponds to the non-volatile memory unit. The non-volatile memory unit stores the judgment result of the arbitration unit when the vehicle power is turned off. When the vehicle power is turned on, if the judgment result of the arbitration unit stored in the non-volatile memory unit indicates that there is a discrepancy between the current value of the steering angle midpoint and the learned value, the detection unit 68 executes a process to initialize the current value of the steering angle midpoint and the learned value.

[0085] With this configuration, when the vehicle power is turned on, the detection unit 68 can detect whether a discrepancy has occurred between the current value and the learned value of the steering angle midpoint during the period from when the vehicle power was last turned on until when the vehicle power is turned off, based on the determination result of the arbitration unit stored in the non-volatile memory unit. Therefore, the process of initializing the current value and the learned value of the steering angle midpoint can be appropriately executed when the vehicle power is turned on. In addition, the non-volatile memory unit retains information even when the operating power is cut off. Therefore, for example, even after the battery has been replaced, the detection unit 68 can obtain the determination result of the arbitration unit from the non-volatile memory unit.

[0086] (3) The steering control device 1 has a processing unit. The processing circuit 53 corresponds to the processing unit. When the vehicle power is turned on, the processing unit executes an initial sequence, which is an initial check at startup. The learning unit has the function of executing an initialization process to initialize the learned value of the steering angle midpoint. The arbitration unit has the function of executing an initialization process to initialize the current value of the steering angle midpoint.

[0087] If the detection unit 68 indicates that the judgment result of the arbitration unit stored in the non-volatile memory unit shows a discrepancy between the current value of the midpoint of the rudder angle and the learned value, it issues an initialization signal S to the learning unit and the arbitration unit requesting them to perform initialization processing. ｒ The learning unit and the arbitration unit generate the initialization signal S. ｒ When the signal is received, initialization is performed during the processing of the initial sequence. With this configuration, the initialization is performed during the processing of the initial sequence. Therefore, the impact of the initialization on the steering system 2 or the vehicle control can be reduced.

[0088] (4) After the detection unit 68 initializes the current value and the learned value of the rudder angle midpoint, the arbitration unit sets the learned value of the rudder angle midpoint as the new current value of the rudder angle midpoint used to control the steering device 2. With this configuration, after the detection unit initializes 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. This makes it possible to suppress the continuation of the initialized state of the rudder angle midpoint value. Initialization includes, for example, erasing the value of the rudder angle midpoint.

[0089] (5) The steering control device 1 includes an absolute angle calculation unit 66. 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 angle is used for the calculation. The absolute angle calculation unit 66 calculates the steering angle θ. ｓ This is transmitted to an external device 54 mounted on the vehicle. With this configuration, the external device 54 mounted on the vehicle receives the steering angle θ calculated by the absolute angle calculation unit 66. ｓ You can use it.

[0090] (6) The arbitration unit sets the initial learned value of the rudder angle midpoint, obtained by a learning process different from that of the learning unit, as the initial value of the rudder 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 rudder angle midpoint θ is learned by the factory learning unit 63. ０３ The fourth midpoint of the rudder angle θ 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 device 2 can be controlled using the initial learned value of the steering angle midpoint before the learning of the first straight-line driving learning unit 61 and the second straight-line driving learning unit 62 is completed.

[0091] <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. ｄIn 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, even after replacing the battery, for example, the current value and learned value of the midpoint of the rudder angle can be retained.

[0092] - 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".

[0093] 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.

[0094] - 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 arbitration unit configured to determine whether a discrepancy has occurred between the current value of the steering angle midpoint and the learned value of the steering angle midpoint; and a detection unit configured to detect, when the vehicle power is turned on, whether the discrepancy occurred during the period from when the vehicle power was last turned on until when it was turned off, based on the determination result of the arbitration unit, wherein the detection unit is configured to perform a process to initialize the current value and the learned value of the steering angle midpoint when the vehicle power is turned on and the determination result of the arbitration unit indicates that the discrepancy has occurred.

2. The steering control device according to claim 1, further comprising a non-volatile storage unit configured to store the determination result of the arbitration unit when the vehicle power is turned off, wherein the detection unit is configured to perform a process to initialize the current value and the learned value of the steering angle midpoint when the vehicle power is turned on and the determination result stored in the non-volatile storage unit indicates the occurrence of the deviation.

3. The steering control device according to claim 1 or 2, further comprising a processing unit configured to execute an initial sequence, which is an initial startup inspection, when the vehicle power is turned on, wherein the learning unit has a function to execute an initialization process to initialize the learned value of the steering angle midpoint, the arbitration unit has a function to execute an initialization process to initialize the current value of the steering angle midpoint, the detection unit is configured to generate an initialization signal requesting the learning unit and the arbitration unit to execute the initialization process when the determination result indicates the occurrence of the deviation, and the learning unit and the arbitration unit are configured to execute the initialization process during the processing of the initial sequence when they receive the initialization signal.

4. The steering control device according to claim 1 or 2, wherein the arbitration unit is 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 claim 1 or 2, further comprising an absolute angle calculation unit configured to calculate the steering angle of the steering wheel as an absolute angle based on the current value of the midpoint of the steering angle, wherein the absolute angle calculation unit is configured to transmit the calculated steering angle to an external device mounted on the vehicle.

6. The steering control device according to claim 1 or 2, wherein the arbitration unit is 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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