Middle point correction device of steering torque sensor, method, and program

Abstract

To provide a middle point correction device, a method, and a program which can perform middle point correction without requiring any special device when no torque is applied to a steering shaft.SOLUTION: A middle point correction device 100 performs middle point correction of a steering torque sensor in a vehicle 102 including: an EPS device 12 for applying control torque to a steering transfer system 34 between a steering wheel 14 and steered wheels 16FL, 16FR; and a steering torque sensor 38 arranged in the steering transfer system. The middle point correction device includes: a non-volatile storage unit 50A; and a control unit 50 for performing a remote operation control of the vehicle. The control unit stores, when performing the remote operation control, steering torque Ts detected by the steering torque sensor as middle point offset amount Tsoff into the storage unit, reads out the middle point offset amount from the storage unit during traveling of the vehicle, and corrects the steering torque detected by the steering torque sensor by the middle point offset amount to perform the middle point correction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device, method, and program for correcting the midpoint of a steering torque sensor mounted on a vehicle such as an automobile. [Background technology]

[0002] A steering torque sensor mounted on a vehicle such as an automobile detects, as steering torque, torque acting on a steering shaft or the like of a steering transmission system between a steering wheel and steered wheels. The steering torque is used not only to control the assist torque of a power steering device but also for cooperative control between the driver's steering and driving assistance control. Therefore, it is necessary for the steering torque sensor to accurately detect the steering torque.

[0003] When no torque is acting on the steering shaft, the steering torque sensor outputs 0, indicating that the steering torque is 0, and when torque is acting on the steering shaft, it outputs a positive or negative value depending on the direction and magnitude of the torque.

[0004] However, due to various external factors, the output of the steering torque sensor may not be zero even when no torque is acting on the steering shaft, resulting in a so-called midpoint (0-point) offset. For this reason, it is known to perform midpoint correction of the steering torque sensor, in which the output of the steering torque sensor in a situation where it is estimated that no torque is acting on the steering shaft is calculated as a midpoint offset amount, and the output of the steering torque sensor is corrected with the midpoint offset amount.

[0005] For example, Patent Document 1 listed below describes a method of checking the accuracy of midpoint detection based on the variation in the detection value of the steering torque sensor when the ignition switch is turned off, and then performing midpoint correction using the detection value of the steering torque sensor as the midpoint offset amount. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-137514 Summary of the Invention

[0007] [Problem to be solved by the invention] However, when the ignition switch is turned off, it does not necessarily mean that no torque is acting on the steering shaft. Also, while it is known to detect a situation in which no torque is acting on the steering shaft and perform midpoint correction, detecting a situation in which no torque is acting on the steering shaft requires a special device such as a camera that captures an image of the driver.

[0008] In an autonomous vehicle, remote driving such as remote parking is sometimes performed, and the driver does not steer the vehicle during remote driving, so no torque acts on the steering shaft.

[0009] The present invention focuses on the fact that no torque acts on the steering shaft during remote driving, and provides a midpoint correction device, method, and program that can perform midpoint correction when no torque acts on the steering shaft without requiring any special device. [Means for solving the problems and effects of the invention] According to the present invention, there is provided a steering torque sensor midpoint correction device (100) that is applied to a vehicle (102) that includes a torque imparting device (EPS device 12) that imparts a control torque to a steering transmission system (34) between a steering wheel (14) and steered wheels (front wheels 16FL, 16FR), and a steering torque sensor (38) that is provided in the steering transmission system between the steering wheel and the torque imparting device, and that is configured to perform midpoint correction of the steering torque sensor.

[0010] The midpoint correction device includes a control unit (driving assistance ECU 50) that performs remote driving control of the vehicle by communicating with a terminal device (96). The control unit includes a nonvolatile storage device (50A) and is configured to store the steering torque (Ts) detected by the steering torque sensor in the storage device while the remote driving control is being performed as a midpoint offset amount (Tsoff) of the steering torque sensor, read the midpoint offset amount from the storage device while the vehicle is traveling, and perform midpoint correction by correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

[0011] Furthermore, according to the present invention, there is provided a method for correcting the midpoint of a steering torque sensor, which is applied to a vehicle (102) including a torque applying device (EPS device 12) that applies a control torque to a steering transmission system (34) between the steering wheel (14) and steered wheels (front wheels 16FL, 16FR), and a steering torque sensor (38) that is provided in the steering transmission system between the steering wheel and the torque applying device, and which performs midpoint correction of the steering torque sensor.

[0012] The midpoint correction method includes steps (S10 to S50) of storing the steering torque (Ts) detected by the steering torque sensor as a midpoint offset amount (Tsoff) of the steering torque sensor in a non-volatile storage device (50A) in a situation where remote driving control of the vehicle is being performed by communicating with a terminal device (96), and a step (S110, S120) of reading the midpoint offset amount from the storage device while the vehicle is traveling and correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

[0013] Furthermore, according to the present invention, there is provided a steering torque sensor midpoint correction program that is applied to a vehicle (102) that includes a torque applying device (EPS device 12) that applies a control torque to a steering transmission system (34) between the steering wheel (14) and steered wheels (front wheels 16FL, 16FR), and a steering torque sensor (38) that is provided in the steering transmission system between the steering wheel and the torque applying device, and that causes an electronic control device (driving assistance ECU 50) mounted on the vehicle to perform midpoint correction of the steering torque sensor.

[0014] The midpoint correction program includes steps (S10 to S50) of storing the steering torque (Ts) detected by the steering torque sensor as a midpoint offset amount (Tsoff) of the steering torque sensor in a non-volatile storage device (50A) when remote driving control of the vehicle is being performed by communicating with a terminal device (96), and a step (S110, S120) of reading the midpoint offset amount from the storage device while the vehicle is traveling and correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

[0015] According to the above-described device, method, and program for correcting the midpoint of a steering torque sensor, when remote driving control of a vehicle is being performed, the steering torque detected by the steering torque sensor is stored in a non-volatile storage device as a midpoint offset amount of the steering torque sensor. When remote driving control of a vehicle is being performed, the driver is out of the vehicle, so no torque acts on the steering transmission system or the steering torque sensor. Therefore, the steering torque detected by the steering torque sensor when no torque is acting on the steering torque sensor can be stored in a non-volatile storage device as an accurate midpoint offset amount of the steering torque sensor.

[0016] Furthermore, the midpoint offset amount is read from the storage device while the vehicle is running, and the steering torque detected by the steering torque sensor is corrected with the midpoint offset amount. Therefore, while the vehicle is running, the steering torque detected by the steering torque sensor can be corrected with an accurate midpoint offset amount.

[0017] Furthermore, the vehicle only needs to be one that can be remotely controlled, and there is no need for a special device to detect when no torque is acting on the steering shaft, such as a camera that photographs the driver. [Mode of the Invention]

[0018] In one aspect of the present invention, the control unit (driving assistance ECU 50) is configured to store (S20, S50) in the storage device (50A) the steering torque (Ts) detected by the steering torque sensor (38) as a midpoint offset amount (Tsoff) of the steering torque sensor after the torque applying device (EPS device 12) applies a vibration torque to the steering transmission system (34).

[0019] According to the above aspect, by applying a vibration torque to the steering transmission system, the torque remaining in the steering transmission system is released, and the steering torque detected by the steering torque sensor thereafter is stored in the storage device as the midpoint offset amount of the steering torque sensor. Therefore, compared to the case where a vibration torque is not applied to the steering transmission system, the risk that the midpoint offset amount will be adversely affected by the torque remaining in the steering transmission system is reduced, and the midpoint offset amount can be determined more accurately.

[0020] In another aspect of the present invention, the remote driving control includes at least one of remote parking control, automatic valet parking control, and smart summon control.

[0021] According to the above aspect, the remote driving control includes at least one of remote parking control, automatic valet parking control, and smart summon control, so that an accurate midpoint offset amount of the steering torque sensor can be obtained when at least one of these controls is being performed.

[0022] In the above description, to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses for the configurations of the invention corresponding to those embodiments. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and / or symbols enclosed in parentheses. Other objects, features, and attendant advantages of the present invention will be easily understood from the following description of the embodiments of the present invention, which will be given with reference to the drawings. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram illustrating a configuration of a midpoint correction device for a steering torque sensor according to an embodiment. [Figure 2] 5 is a flowchart showing a routine for midpoint offset amount detection control in the first embodiment. [Figure 3] 4 is a flowchart showing a routine for midpoint correction control in the first embodiment. [Figure 4] 10 is a flowchart showing a routine for midpoint offset amount detection control in a second embodiment. [Figure 5] 10 is a flowchart showing a routine for midpoint offset amount detection control in a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0025] 1, a midpoint correction device 100 for a steering torque sensor according to an embodiment is applied to a vehicle 102, and includes a steering device 10, an electric power steering ECU 40, and a driving assistance ECU 50. The vehicle 102 may be an autonomously driven vehicle, and includes a drive ECU 60, a braking ECU 70, and a meter ECU 80. In this specification, the electric power steering will be referred to as EPS (short for Electric Power Steering) as necessary.

[0026] Each ECU, such as the EPS ECU 40 and the driving assistance ECU 50, is an electronic control unit (Electronic Control Unit) that includes a microcomputer as its main component, and is connected to each other via a CAN (Controller Area Network) 104 so that they can send and receive information. Each microcomputer includes a CPU, ROM, RAM, and an interface. The CPU performs various functions by executing instructions (programs, routines) stored in the ROM. These ECUs may be integrated into a single ECU. In particular, the driving assistance ECU 50 includes a readable / writable nonvolatile storage device.

[0027] 1, the steering device 10 includes an EPS device 12 connected to an EPS ECU 40. The EPS device 12 is configured as a rack-and-pinion EPS device that is driven in response to the driver's operation of a steering wheel 14. A rack bar 18 of the EPS device 12 is connected to knuckle arms (not shown) of front wheels 16FL and 16FR, which are steered wheels, via tie rods 20L and 20R. The steering wheel 14 is connected to a pinion shaft 26 of the EPS device 12 via a steering shaft 22 and a universal joint 24.

[0028] In the illustrated embodiment, the EPS device 12 is a rack-assist type electric power steering device, and includes an electric motor 28 and a conversion mechanism 30, such as a belt type, that converts the rotation and torque of the electric motor 28 into a displacement and force in a reciprocating direction and transmits the displacement and force to the rack bar 18. The EPS device 12 generates a control torque by driving the rack bar 18 relative to a housing 32.

[0029] Therefore, the steering shaft 22, universal joint 24, pinion shaft 26, EPS device 12, and tie rods 20L, 20R constitute a steering transmission system 34 that transmits steering displacement and torque between the steering wheel 14 and the front wheels 16FL, 16FR. The EPS device 12 functions as a torque applying device that applies a control torque to the steering shaft 22 of the steering transmission system 34.

[0030] A steering angle sensor 36 that detects the steering angle θs is provided on the steering shaft 22, and a steering torque sensor 38 that detects the steering torque Ts is provided on the pinion shaft 26. The steering angle θs and the steering torque Ts are assumed to be positive values when the vehicle 102 turns right due to the driver's steering operation. Therefore, the steering torque Ts is positive when the relative rotation of the member on the steering wheel 14 side and the member on the EPS device 12 side with respect to the torsion bar (not shown) of the steering torque sensor 38 corresponds to the relative rotation in the direction in which the vehicle is turning right.

[0031] The EPS device 12 may be a pinion-assist or column-assist EPS device as long as it can apply a control torque to the steering transmission system 34. The steering torque sensor 38 may be provided at any position in the steering transmission system 34 as long as it is provided closer to the steering wheel 14 than the EPS device 12.

[0032] The EPS-ECU 40 controls the steering assist torque and reduces the driver's steering burden by controlling the EPS device 12 in a manner known in the art based on the steering torque Ts and vehicle speed V detected by a driving operation sensor 90 and a vehicle state sensor 92 (described later). The EPS-ECU 40 also controls the EPS device 12 to steer the front wheels 16FL and 16FR as needed. Thus, the EPS-ECU 40 and the EPS device 12 function as an automatic steering device 42 that automatically steers the front wheels as needed.

[0033] A camera sensor 52 and a radar sensor 54 are connected to the driving assistance ECU 50. The camera sensor 52 and the radar sensor 54 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 52 and the radar sensor 54 function as a target information acquisition device 56 that acquires information about targets at least ahead of the vehicle 102. Note that a LiDAR (Light Detection and Ranging) may be used instead of or in addition to the radar sensor 54.

[0034] Furthermore, a setting operator 58 is connected to the driving assistance ECU 50, and the setting operator 58 is provided at a position where it can be operated by the driver. Although not shown in Fig. 1, in this embodiment, the setting operator 58 includes a remote driving switch.

[0035] A drive unit 62 that accelerates the vehicle 102 by applying drive force to drive wheels not shown in Fig. 1 is connected to the drive ECU 60. Under normal circumstances, the drive ECU 60 controls the drive unit 62 so that the drive force generated by the drive unit 62 varies in response to the driving operation by the driver, and when a command signal is received from the driving assistance ECU 50, the drive ECU 60 controls the drive unit 62 based on the command signal.

[0036] The braking ECU 70 is connected to a braking device 72 that applies braking force to wheels not shown in Fig. 1 to decelerate the vehicle 102. Under normal circumstances, the braking ECU 70 controls the braking device so that the braking force generated by the braking device 72 changes in response to the braking operation by the driver, and when a command signal is received from the steering assist ECU 50, the braking ECU 70 performs automatic braking by controlling the braking device 72 based on the command signal.

[0037] The driving operation sensor 90 and the vehicle state sensor 92 are connected to the CAN 104. Information detected by the driving operation sensor 90 and the vehicle state sensor 92 (referred to as sensor information) is transmitted to the CAN 104. The driving operation sensor 90 includes a driving operation amount sensor and a braking operation amount sensor. The vehicle state sensor 92 includes a vehicle speed sensor, a longitudinal acceleration sensor, a lateral acceleration sensor, a yaw rate sensor, etc.

[0038] Furthermore, a transmitter / receiver 94 is connected to the CAN 104. The transmitter / receiver 94 communicates with a terminal device 96, such as a smartphone, by wireless communication such as Bluetooth (registered trademark) or communication via the Internet. Based on commands input from the terminal device 96 via the transmitter / receiver 94, the driving assistance ECU 50 controls the automatic steering device 42 to automatically steer the front wheels 16FL and 16FR, and controls the drive device 62 and the brake device 72 to control the braking / driving force, thereby performing remote driving control.

[0039] The driving assistance ECU 50 is a central control device that performs driving assistance control such as remote driving control, midpoint offset amount detection control of the steering torque sensor, midpoint correction control of the steering torque sensor, lane keeping control, etc. In this embodiment, when the remote driving switch is on and the remote driving control application of the terminal device 96 is running, the driving assistance ECU 50 executes remote driving control in cooperation with the transceiver device 94, the terminal device 96, and other ECUs.

[0040] The remote driving control may be at least one of remote parking control, automatic valet parking control, and smart summon control, in which the driver or another user remotely controls the vehicle by operating the terminal device 96. Remote parking control is control in which the vehicle is parked in a predetermined parking position by remote operation while the driver is out of the vehicle, and the vehicle is then removed from the parking position. Automatic valet parking control is control in which, in parking lots at large facilities, the vehicle is handed over, driven to and from the parking position, parked, and removed by unmanned automatic driving, except when the user gets in or out at the entrance / exit. Smart summon control is control in which the vehicle is automatically driven to the driver's position or a specified position without the driver being in the vehicle. Remote driving control is not a gist of the present invention and may be performed in any manner known in the technical field.

[0041] Furthermore, in a situation where remote driving control is being performed, the driving assistance ECU 50 performs control to detect a midpoint offset amount of the steering torque sensor, thereby storing the steering torque Ts detected by the steering torque sensor 38 as a midpoint offset amount Tsoff of the steering torque sensor in the storage device 50A. Furthermore, while the vehicle 102 is traveling, the driving assistance ECU 50 performs control to correct the midpoint of the steering torque sensor, thereby performing midpoint correction to correct the steering torque Ts detected by the steering torque sensor 38 with the midpoint offset amount Tsoff.

[0042] [First embodiment] In the first embodiment, the ROM of the steering assist ECU 50 stores a program for detecting a midpoint offset amount of the steering torque sensor and a program for correcting a midpoint of the steering torque sensor, which programs correspond to the flowcharts shown in Figures 2 and 3. The CPU executes the control for detecting a midpoint offset amount of the steering torque sensor and the control for correcting a midpoint of the steering torque sensor in accordance with these programs. <Midpoint Offset Amount Detection Control Routine of the First Embodiment>

[0043] The midpoint offset amount detection control according to the flowchart shown in Fig. 2 is repeatedly executed at predetermined time intervals by the CPU of the driving assistance ECU 50 when a remote operation switch (not shown in Fig. 1) of the setting operation device 58 is on. Furthermore, at the start of the midpoint offset amount detection control, a count value N (an integer equal to or greater than 0) indicating the number of times a midpoint offset amount, which will be described later, has been detected is reset to an initial value of 0. Note that these also apply to midpoint offset amount detection control in other embodiments, which will be described later.

[0044] First, in step S10, the CPU determines whether remote driving control is in progress, i.e., whether remote driving control is being executed to control automatic steering and braking / driving force based on commands input from the terminal device 96 via the transceiver device 94. The vehicle 102 may be in either a moving state or a stationary state. If a negative determination is made, step S10 is executed again, and if a positive determination is made, the control proceeds to step S30.

[0045] In step S30, the CPU reads the steering torque Ts detected by the steering torque sensor 38 from the EPS·ECU 40 via the CAN 104.

[0046] In step S40, the CPU determines whether or not the midpoint offset amount Tsoff of the steering torque sensor needs to be updated. Specifically, where α is a positive constant, it is determined whether or not the absolute value of the steering torque Ts is smaller than the value obtained by subtracting α from the absolute value of the midpoint offset amount Tsoff stored in the storage device 50A, or greater than the sum of the absolute value of the midpoint offset amount Tsoff and α. If a negative determination is made, the control proceeds to step S60, and if a positive determination is made, the control proceeds to step S50.

[0047] In step S50, the CPU stores the steering torque Ts in the storage device 50A as the midpoint offset amount Tsoff of the steering torque sensor.

[0048] In step S60, the CPU increments by one the count value N, which indicates the number of times the midpoint offset amount has been detected.

[0049] In step S70, the CPU determines whether the count value N is equal to or greater than a reference value Nc (a fixed positive integer such as 3). If the CPU determines that the count value N is not equal to or greater than a reference value Nc (a fixed positive integer such as 3), the control returns to step S10, and if the CPU determines that the count value N is not equal to or greater than a reference value Nc, the control ends. <Midpoint Correction Control Routine of the First Embodiment>

[0050] The midpoint correction control according to the flowchart shown in Fig. 3 is repeatedly executed at predetermined time intervals by the CPU of the driving assistance ECU 50 when an ignition switch not shown in Fig. 1 is on. Note that the midpoint correction control according to the flowchart shown in Fig. 3 may also be repeatedly executed at predetermined time intervals by the CPU of the EPS-ECU 40.

[0051] First, in step S110, the CPU determines whether or not the vehicle 102 is under remote driving control, similar to step S10. Note that the vehicle 102 may be in either a moving or stationary state. If a positive determination is made, this control is temporarily terminated, and if a negative determination is made, this control proceeds to step S120.

[0052] In step S120, the CPU reads the steering torque Ts detected by the steering torque sensor 38 from the EPS·ECU 40 via the CAN 104. Furthermore, the CPU reads the midpoint offset amount Tsoff from the storage device 50A.

[0053] In step S120, the CPU outputs a value Ts-Tsoff obtained by subtracting the midpoint offset amount Tsoff from the steering torque Ts as the corrected steering torque Ts. The corrected steering torque Ts may be used for various driving assistance controls of the vehicle 102 in addition to the control of the steering assist torque.

[0054] [Second embodiment] In the second embodiment, the ROM of the steering assist ECU 50 stores a program for detecting a midpoint offset amount of the steering torque sensor and a program for correcting a midpoint of the steering torque sensor, which correspond to the flowcharts shown in Figures 4 and 3, respectively. The CPU executes the control for detecting a midpoint offset amount of the steering torque sensor and the control for correcting a midpoint of the steering torque sensor in accordance with these programs. The control for correcting a midpoint of the steering torque sensor is the same as the control for correcting a midpoint of the steering torque sensor in the first embodiment, and therefore a description of this control will be omitted. <Midpoint Offset Amount Detection Control Routine of Second Embodiment>

[0055] In the second embodiment, if a positive determination is made in step S10, the control proceeds to step S20. As can be seen from a comparison between Fig. 4 and Fig. 2, the steps other than step S20 are executed in the same manner as in the first embodiment.

[0056] In step S20, the CPU outputs a command signal to the EPS-ECU 40, thereby causing the EPS device 12 to apply a vibration torque to the steering shaft 22 of the steering transmission system 34. The vibration torque is a vibration torque of a magnitude that can release residual torque in the steering shaft caused by friction between the steering shaft 22 and a support device that rotatably supports the steering shaft 22, and does not steer the front wheels 16FL and 16FR.

[0057] [Third embodiment] In the third embodiment, although not shown in Fig. 1, the camera sensor 52 includes a driver monitor camera that captures images of the driver's seat from the front to the rear, in addition to a camera that captures images of the surroundings of the vehicle 102. Also, although not shown in Fig. 1, the driving operation sensor 90 includes a touch sensor. The touch sensor is provided on the steering wheel 14 and detects that the steering wheel is being held by the driver's hands.

[0058] Furthermore, in the third embodiment, the ROM of the steering assist ECU 50 stores a program for detecting a midpoint offset amount of the steering torque sensor and a program for correcting a midpoint of the steering torque sensor, which correspond to the flowcharts shown in Figures 5 and 3, respectively. The CPU executes the control for detecting a midpoint offset amount of the steering torque sensor and the control for correcting a midpoint of the steering torque sensor in accordance with these programs. The control for correcting a midpoint of the steering torque sensor is the same as the control for correcting a midpoint of the steering torque sensor in the first embodiment, and therefore a description of this control will be omitted. <Midpoint Offset Amount Detection Control Routine of the Third Embodiment>

[0059] In the third embodiment, if a positive determination is made in step S10, the control proceeds to step S12. As can be seen from a comparison between Fig. 5 and Fig. 2, the steps other than steps S12 and S14 are executed in the same manner as in the first embodiment.

[0060] In step S12, the CPU determines whether or not the driver is in the vehicle 102 and sitting in the driver's seat based on the results of analyzing the image captured by the driver monitor camera. If a negative determination is made, the control proceeds to step S30, and if a positive determination is made, the control proceeds to step S14.

[0061] In step S14, the CPU determines, based on the detection result of the touch sensor, whether or not the driver is holding the steering wheel 14. If a positive determination is made, the control returns to step S10, and if a negative determination is made, the control proceeds to step S30.

[0062] As can be seen from the above description, according to each embodiment, when remote driving control of the vehicle is being performed (S10), the steering torque Ts detected by the steering torque sensor 38 is stored in the non-volatile storage device 50A as the midpoint offset amount Tsoff of the steering torque sensor. When remote driving control of the vehicle is being performed, the driver has dismounted from the vehicle, so no torque acts on the steering transmission system 34 and the steering torque sensor 38. Therefore, the steering torque detected by the steering torque sensor when no torque is acting on the steering torque sensor can be stored in the non-volatile storage device as an accurate midpoint offset amount of the steering torque sensor.

[0063] Furthermore, the midpoint offset amount is read from the storage device while the vehicle is running, and the steering torque Ts detected by the steering torque sensor is corrected with the midpoint offset amount Tsoff. Therefore, while the vehicle is running, the steering torque detected by the steering torque sensor can be corrected with an accurate midpoint offset amount.

[0064] Furthermore, according to each embodiment, the remote driving control includes at least one of remote parking control, automatic valet parking control, and smart summon control, so that an accurate midpoint offset amount of the steering torque sensor 38 can be obtained when at least one of these controls is being performed.

[0065] In particular, according to the first and second embodiments, the vehicle only needs to be one that can be remotely driven, and no special device such as a camera that photographs the driver is required to detect a situation where no torque is acting on the steering shaft 22.

[0066] Furthermore, according to the second embodiment, by applying a vibration torque to the steering transmission system 34, the torque remaining in the steering transmission system is released, and thereafter the steering torque Ts detected by the steering torque sensor 38 is stored in the storage device 50A as the midpoint offset amount Tsoff of the steering torque sensor. Therefore, compared to the case where a vibration torque is not applied to the steering transmission system, it is possible to reduce the risk that the midpoint offset amount will be adversely affected by the torque remaining in the steering transmission system, and it is possible to more accurately determine the midpoint offset amount.

[0067] Although the present invention has been described in detail above with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the above-described embodiments, and that various other embodiments are possible within the scope of the present invention.

[0068] For example, in each of the above-described embodiments, it is determined in step S40 whether or not the midpoint offset amount Tsoff of the steering torque sensor needs to be updated based on the steering torque Ts detected by the steering torque sensor 38 and read in step S30. However, the steering torque used for the determination in step S40 may be an average value of the steering torque Ts read in step S30 over a predetermined control cycle.

[0069] In the above embodiment, in step S60, the count value N indicating the number of times the midpoint offset amount has been detected is incremented by 1, and in step S70, it is determined whether the count value N is equal to or greater than the reference value Nc. If a negative determination is made, the control returns to step S10. However, steps S60 and S70 may be omitted, and steps S30 to S50 may be repeatedly executed while the remote operation control is being executed.

[0070] In the second embodiment, in step S20, the EPS device 12 applies a vibration torque to the steering shaft 22 of the steering transmission system 34, and then in step S30, the steering torque Ts detected by the steering torque sensor 38 is read. However, step S20 may be executed when a positive determination is made in step S10 for the first time, and when a positive determination is made in step S10 for the second or subsequent times, step S20 may be skipped and the control may proceed to step S30 without executing step S20.

[0071] In the third embodiment, if it is determined in step S12 that the driver is seated in the driver's seat, it is determined in step S14 whether the steering wheel 14 is being held by the driver's hands. If a negative determination is made, the control proceeds to step S30. However, one of steps S12 and S14 may be omitted. If step S14 is omitted, the control returns to step S10 if a positive determination is made in step S12, and proceeds to step S30 if a negative determination is made.

[0072] Furthermore, in the third embodiment, step S20 is not performed, but step S20 may also be performed in the third embodiment. [Explanation of symbols]

[0073] 10...Steering device, 12...EPS device, 14...Steering wheel, 16FL, 16FR...Front wheels, 40...EPS ECU, 50...Driver assistance ECU, 50A...Storage device, 60...Drive ECU, 70...Braking ECU, 100...Near point correction device for steering torque sensor, 102...Vehicle

Claims

1. A steering torque sensor midpoint correction device is applied to a vehicle equipped with a torque applying device that applies a control torque to a steering transmission system between a steering wheel and steered wheels, and a steering torque sensor that is provided in the steering transmission system between the steering wheel and the torque applying device, and is configured to perform midpoint correction of the steering torque sensor, a control unit that performs remote driving control of a vehicle by communicating with a terminal device, the control unit including a nonvolatile storage device, and configured to store the steering torque detected by the steering torque sensor in the storage device as a midpoint offset amount of the steering torque sensor while the remote driving control is being performed, read the midpoint offset amount from the storage device while the vehicle is running, and perform the midpoint correction by correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

2. 2. The midpoint correction device for a steering torque sensor according to claim 1, wherein the control unit is configured to store in the storage device the steering torque detected by the steering torque sensor after the torque applying device applies a vibration torque to the steering transmission system as a midpoint offset amount of the steering torque sensor.

3. 2. The device for correcting a midpoint of a steering torque sensor according to claim 1, wherein the remote driving control includes at least one of a remote parking control, an automatic valet parking control, and a smart summon control.

4. A method for correcting a midpoint of a steering torque sensor, which is applied to a vehicle including a torque applying device that applies a control torque to a steering transmission system between a steering wheel and steered wheels, and a steering torque sensor that is provided in the steering transmission system between the steering wheel and the torque applying device, and which performs midpoint correction of the steering torque sensor, A method for correcting a midpoint of a steering torque sensor, comprising: a step of storing the steering torque detected by the steering torque sensor in a non-volatile storage device as a midpoint offset amount of the steering torque sensor in a situation where remote driving control of a vehicle is being performed by communicating with a terminal device; and a step of reading the midpoint offset amount from the storage device while the vehicle is traveling and correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

5. A steering torque sensor midpoint correction program is applied to a vehicle equipped with a torque applying device that applies a control torque to a steering transmission system between a steering wheel and steered wheels, and a steering torque sensor that is provided in the steering transmission system between the steering wheel and the torque applying device, and causes an electronic control device mounted on the vehicle to perform midpoint correction of the steering torque sensor, A midpoint correction program for a steering torque sensor, comprising: a step of storing the steering torque detected by the steering torque sensor in a non-volatile storage device as a midpoint offset amount of the steering torque sensor in a situation where remote driving control of the vehicle is being performed by communicating with a terminal device; and a step of reading the midpoint offset amount from the storage device while the vehicle is traveling and correcting the steering torque detected by the steering torque sensor with the midpoint offset amount.

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