Midpoint correction device, method, and program for steering torque sensor

Abstract

A midpoint correction device is applied to a vehicle provided with: an EPS device that applies a control torque to a steering transmission system between a steering wheel and a steering wheel; and a steering torque sensor provided in the steering transmission system, the midpoint correction device performing midpoint correction of the steering torque sensor, the midpoint correction device including a control unit including a non-volatile storage device and performing remote driving control of the vehicle, the control unit stores the steering torque detected by the steering torque sensor as a midpoint offset amount in the storage device when remote driving control is being performed, reads the midpoint offset amount from the storage device while the vehicle is traveling, and corrects the steering torque detected by the steering torque sensor using the midpoint offset amount. Therefore, midpoint correction is performed.

Description

Technical Field

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

[0002] Steering torque sensors installed in vehicles such as automobiles detect torque acting on the steering shaft of the steering transmission system between the steering wheel and the steering wheels as steering torque. Steering torque is used not only to control the assist torque of the electric power steering system but also to coordinate the driver's steering with the driver assistance system. Therefore, it is essential for a steering torque sensor to accurately detect steering torque.

[0003] When there is no torque acting on the steering shaft, the steering torque sensor outputs 0, indicating that the steering torque is 0. When there is torque acting on the steering shaft, the output is 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 (zero-point) offset. Therefore, the output of the steering torque sensor, presumably when no torque is acting on the steering shaft, is calculated as the midpoint offset. Subsequently, a midpoint correction of the steering torque sensor is performed, which uses the midpoint offset to correct the output of the steering torque sensor. This is well known.

[0005] For example, Japanese Patent Application Laid-Open No. 2009-137514 describes the following: The reliability of midpoint detection is confirmed based on fluctuations in the steering torque sensor's detection value when the ignition switch is off. Midpoint correction is then performed using the steering torque sensor's detection value as a midpoint offset. Summary of the Invention

[0006] However, when the ignition switch is off, there is not necessarily no torque acting on the steering shaft. In addition, although it is known to detect the absence of torque on the steering shaft and perform mid-point correction, detecting the absence of torque on the steering shaft requires special equipment such as a camera that captures the driver's image.

[0007] In vehicles capable of autonomous driving, remote driving, such as remote parking, is sometimes performed while the driver is out of the vehicle. Therefore, during remote driving, the driver does not operate the steering, so no torque is applied to the steering axis.

[0008] The present invention focuses on the fact that no torque acts on the steering shaft during long-distance driving, and provides a center point correction device, method and program that can perform center point correction under the condition that no torque acts on the steering shaft without requiring special devices. According to the present invention, a midpoint correction device (100) for a steering torque sensor is provided, which is suitable for a vehicle (102) comprising: a torque application device (EPS device 12) for applying a control torque to a steering transmission system (34) between a steering wheel (14) and steering wheels (front wheels 16FL, 16FR); and a steering torque sensor (38) provided in the steering transmission system between the steering wheel and the torque application device, wherein the midpoint correction device is configured to perform midpoint correction of the steering torque sensor.

[0009] The midpoint correction device includes a control unit (driving assistance ECU 50) for remote driving control of a vehicle by communicating with a terminal device (96), the control unit including a non-volatile storage device (50A) and configured to store the steering torque (Ts) detected by the steering torque sensor as the midpoint offset (Tsoff) of the steering torque sensor in the storage device when the remote driving control is being performed, read the midpoint offset from the storage device when the vehicle is traveling, and use the midpoint offset to correct the steering torque detected by the steering torque sensor, thereby performing midpoint correction.

[0010] In addition, according to the present invention, a midpoint correction method for a steering torque sensor is provided, which is applicable to the following vehicle (102), wherein the vehicle (102) comprises: a torque application device (EPS device 12) which applies a control torque to a steering transmission system (34) between a steering wheel (14) and steering wheels (front wheels 16FL, 16FR); and a steering torque sensor (38) which is arranged in the steering transmission system between the steering wheel and the torque application device. In the midpoint correction method, midpoint correction of the steering torque sensor is performed.

[0011] The midpoint correction method includes: steps (S10 to S50) of storing the steering torque (Ts) detected by the steering torque sensor as the midpoint offset (Tsoff) of the steering torque sensor in a non-volatile storage device (50A) while the vehicle is being remotely controlled by communicating with a terminal device (96); and a step (S130) of reading the midpoint offset (S110, S120) from the storage device while the vehicle is traveling and correcting the steering torque detected by the steering torque sensor using the midpoint offset.

[0012] Furthermore, according to the present invention, a midpoint correction program for a steering torque sensor is provided, which is applicable to the following vehicle (102), wherein the vehicle (102) comprises: a torque applying device (EPS device 12) which applies a control torque to a steering transmission system (34) between a steering wheel (14) and steering wheels (front wheels 16FL, 16FR); and a steering torque sensor (38) which is arranged in the steering transmission system between the steering wheel and the torque applying device, wherein the midpoint correction program causes an electronic control unit (driving assistance ECU 50) mounted on the vehicle to perform midpoint correction of the steering torque sensor.

[0013] The midpoint correction program causes the electronic control device to execute the following steps: when the vehicle is being remotely controlled by communicating with a terminal device (96), the steering torque (Ts) detected by the steering torque sensor is stored as the midpoint offset (Tsoff) of the steering torque sensor in a non-volatile storage device (50A) (S10 to S50); and when the vehicle is traveling, the midpoint offset (S110, S120) is read from the storage device and the steering torque detected by the steering torque sensor is corrected using the midpoint offset (S130).

[0014] According to the aforementioned steering torque sensor midpoint correction device, method, and program, while remote control of the vehicle is in progress, the steering torque detected by the steering torque sensor is stored in a non-volatile storage device as the midpoint offset of the steering torque sensor. Since the driver has exited the vehicle while remote control is in progress, no torque is applied to the steering transmission system or the steering torque sensor. Therefore, the steering torque detected by the steering torque sensor can be stored in the non-volatile storage device as the accurate midpoint offset of the steering torque sensor, even when no torque is applied to the steering torque sensor.

[0015] Furthermore, the midpoint offset is read from the storage device while the vehicle is running and is used to correct the steering torque detected by the steering torque sensor.

[0016] Furthermore, the vehicle only needs to be a vehicle capable of remote driving control, and no special device for detecting a situation where no torque is acting on the steering shaft, such as a camera for photographing the driver, is required.

[0017] In one embodiment of the present invention, a control unit (driving assistance ECU 50) is configured to store a steering torque (Ts) detected by a steering torque sensor (38) as a midpoint offset (Tsoff) of the steering torque sensor in a storage device (50A) (S20, S50) after a vibration torque is applied to a steering transmission system (34) by a torque application device (EPS device 12).

[0018] According to the above embodiment, by applying a vibration torque to the steering transmission system, the torque remaining in the steering transmission system is released. The steering torque subsequently detected by the steering torque sensor is stored in the storage device as the midpoint offset of the steering torque sensor. Therefore, compared to a case where no vibration torque is applied to the steering transmission system, the possibility of the midpoint offset being adversely affected by the torque remaining in the steering transmission system is reduced, allowing the midpoint offset to be determined more accurately.

[0019] In another embodiment of the present invention, the remote driving control includes at least one of remote parking control, automatic valet parking control, and smart summon control.

[0020] 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. Therefore, the accurate midpoint offset of the steering torque sensor can be obtained while the at least one control is in progress.

[0021] In the above description, to facilitate understanding of the present invention, the names and / or reference numerals used in the embodiments described below are added in parentheses to the components of the invention corresponding to the embodiments described below. However, the components of the present invention are not limited to the components of the embodiments corresponding to the names and / or reference numerals added in parentheses. Other objects, other features, and additional advantages of the present invention should be readily understood from the description of the embodiments of the present invention described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which: Figure 1 1 is a schematic diagram showing the configuration of a mid-point correction device for a steering torque sensor according to an embodiment; Figure 2 is a flowchart showing a routine of midpoint shift amount detection control in the first embodiment; Figure 3 is a flowchart showing a routine of midpoint correction control in the first embodiment; Figure 4is a flowchart showing a routine of midpoint shift amount detection control in the second embodiment; and Figure 5 1 is a flowchart showing a routine of midpoint shift amount detection control in the third embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a steering torque sensor midpoint correction device 100 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. Vehicle 102 may be a vehicle capable of autonomous driving and includes a drive ECU 60, a brake ECU 70, and an instrument ECU 80. In this specification, electric power steering is referred to as EPS (Electric Power Steering), as needed.

[0025] Each ECU, such as the EPS·ECU 40 and the driving assistance ECU 50, is an Electronic Control Unit (ECU), which has a microcomputer as its main component. Each ECU, such as the EPS·ECU 40 and the driving assistance ECU 50, is connected via a CAN (Controller Area Network) 104 so as to be able to send and receive information to each other. Each microcomputer includes a CPU, ROM, RAM, and an interface. The CPU implements various functions by executing commands (programs, routines) stored in the ROM. These ECUs can also be integrated into one ECU. In particular, the driving assistance ECU 50 includes a non-volatile storage device that can be read and written.

[0026] like Figure 1 As shown, the steering system 10 includes an EPS device 12 connected to an EPS ECU 40. The EPS device 12 is a rack-and-pinion type EPS device that is driven in response to the driver's operation of a steering wheel 14. The rack 18 of the EPS device 12 is connected to the knuckle arms (not shown) of the front wheels 16FL and 16FR, which serve as steering wheels, via tie rods 20L and 20R. The steering wheel 14 is connected to the pinion shaft 26 of the EPS device 12 via a steering shaft 22 and a universal joint 24.

[0027] In the illustrated embodiment, the EPS device 12 is a rack-assisted electric power steering device. The EPS device 12 includes a motor 28 and a conversion mechanism 30. The conversion mechanism 30 converts the rotation and torque of the motor 28 into displacement and force in the reciprocating direction and transmits the displacement and force to the rack 18. The conversion mechanism 30 is, for example, a belt-type. The EPS device 12 generates control torque by driving the rack 18 relative to the housing 32.

[0028] Thus, the steering shaft 22, universal joint 24, pinion shaft 26, EPS device 12, and tie rods 20L and 20R constitute a steering transmission system 34. The steering transmission system 34 transmits steering displacement and torque between the steering wheel 14 and the front wheels 16FL and 16FR. The EPS device 12 functions as a torque applying device that applies control torque to the steering shaft 22 of the steering transmission system 34.

[0029] A steering angle sensor 36 is provided on the steering shaft 22 to detect the steering angle θs, and a steering torque sensor 38 is provided on the pinion shaft 26 to detect the steering torque Ts. The steering angle θs and the steering torque Ts are set to take positive values when the vehicle 102 turns right due to the driver's steering operation. Therefore, when the relative rotation of the components on the steering wheel 14 side and the components on the EPS device 12 side relative to the torsion bar (not shown) of the steering torque sensor 38 corresponds to the vehicle's right turn, the steering torque Ts takes a positive value.

[0030] Furthermore, the EPS device 12 may be a pinion-assisted or column-assisted EPS device as long as it can apply control torque to the steering transmission system 34. Furthermore, the steering torque sensor 38 may be located at any position in the steering transmission system 34 as long as it is located closer to the steering wheel 14 than the EPS device 12.

[0031] The EPS·ECU 40 controls the EPS device 12 based on the steering torque Ts and vehicle speed V detected by the driving operation sensor 90 and the vehicle state sensor 92 (described later), thereby controlling the steering assist torque. This reduces the driver's steering burden. In addition, by controlling the EPS device 12, the EPS·ECU 40 can steer the front wheels 16FL and 16FR as needed. Therefore, the EPS·ECU 40 and the EPS device 12 function as an automatic steering device 42 that automatically steers the front wheels as needed.

[0032] The driving assistance ECU 50 is connected to a camera sensor 52 and a radar sensor 54. The camera sensor 52 and the radar sensor 54 include multiple camera devices and multiple radar devices, respectively. The camera sensor 52 and the radar sensor 54 function as a target information acquisition device 56 that acquires information about at least a target in front of the vehicle 102. Alternatively, a LiDAR (Light Detection and Ranging) system may be used in place of the radar sensor 54, or in addition to the radar sensor 54.

[0033] Furthermore, a setting operator 58 is connected to the driving support ECU 50, and the setting operator 58 is provided at a position where it is operated by the driver. Figure 1 Not shown, but in an embodiment, the setting operator 58 includes a remote steering switch.

[0034] The drive ECU 60 is connected to the Figure 1 The drive device 62 applies driving force to the drive wheels (not shown) to accelerate the vehicle 102. The drive ECU 60 normally controls the drive device 62 so that the driving force generated by the drive device 62 varies according to the driving operation performed by the driver. When receiving a command signal from the driving assistance ECU 50, the drive device 62 is controlled based on the command signal.

[0035] The brake ECU 70 is connected to the Figure 1 The brake ECU 70 applies braking force to the wheels (not shown) to decelerate the vehicle 102. The brake ECU 70 normally controls the brake ECU 72 so that the braking force generated by the brake ECU 72 varies according to the driver's braking operation. Upon receiving a command signal from the steering assist ECU 50, the brake ECU 70 controls the brake ECU 72 based on the command signal, thereby performing automatic braking.

[0036] 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, and a yaw rate sensor.

[0037] Furthermore, the transceiver 94 is connected to the CAN 104. The transceiver 94 communicates with a terminal device 96, such as a smartphone, via wireless communication such as Bluetooth (registered trademark) or Internet-based communication. Based on commands input from the terminal device 96 via the transceiver 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 and driving forces, thereby performing remote driving control.

[0038] The driving assistance ECU 50 is a central control device that performs driving assistance controls such as remote driving control, steering torque sensor midpoint offset detection control, steering torque sensor midpoint correction control, and lane keeping control. In the embodiment, when the remote driving switch is turned on and the remote driving control application on the terminal device 96 is activated, the driving assistance ECU 50 cooperates with the transceiver 94, the terminal device 96, and other ECUs to execute remote driving control.

[0039] In addition, 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 other users operate the terminal device 96 to remotely operate the vehicle. Remote parking control is a control that parks the vehicle at a specified parking position and unloads the vehicle from the parking position through remote operation when the driver has gotten off the vehicle. Automatic valet parking control is a control that performs vehicle handovers and round-trips to parking positions, parking, and unloading in parking lots of large facilities, etc., through unmanned automatic driving, except when users get on and off the vehicle at entrances and exits. Smart summon control is a control that summons the vehicle to the driver's position or a designated position through automatic driving without the driver getting on the vehicle. Remote driving control does not constitute the main purpose of the present invention and can be performed in any manner known in the technical field.

[0040] Furthermore, when remote driving control is in effect, the driving assistance ECU 50 performs steering torque sensor midpoint offset detection control, thereby storing the steering torque Ts detected by the steering torque sensor 38 as the steering torque sensor midpoint offset Tsoff in the storage device 50A. Furthermore, while the vehicle 102 is traveling, the driving assistance ECU 50 performs steering torque sensor midpoint correction control, thereby performing midpoint correction to correct the steering torque Ts detected by the steering torque sensor 38 using the midpoint offset Tsoff. First embodiment

[0041] In the first embodiment, the ROM of the steering assist ECU 50 stores the Figure 2 and Figure 3The flowchart shown corresponds to a program for detecting and controlling the center point offset of the steering torque sensor and a program for controlling the center point correction of the steering torque sensor. The CPU executes the center point offset detection and control of the steering torque sensor and the center point correction control of the steering torque sensor according to these programs. Midpoint shift amount detection control routine of the first embodiment

[0042] based on Figure 2 The midpoint offset detection control in the flowchart shown in FIG. 1 is performed by setting the operator 58. Figure 1 When the remote driving switch (not shown) is turned on, the CPU of the driving assistance ECU 50 repeatedly executes the control at predetermined intervals. Furthermore, at the start of the midpoint offset detection control, a count value N (an integer greater than or equal to 0) indicating the number of midpoint offset detections, described later, is reset to an initial value of 0. These aspects also apply to the midpoint offset detection control in other embodiments described later.

[0043] First, in S10, the CPU determines whether remote driving control is in effect, that is, whether remote driving control is being executed, in which automatic steering and braking / driving force control are performed based on commands input from the terminal device 96 via the transceiver 94. The vehicle 102 may be in either a driving state or a stationary state. If a negative determination is made, S10 is executed again. If an affirmative determination is made, the control proceeds to S30.

[0044] In S30 , the CPU reads the steering torque Ts detected by the steering torque sensor 38 from the EPS·ECU 40 via the CAN 104 .

[0045] In S40, the CPU determines whether the steering torque sensor's midpoint offset Tsoff needs to be updated. Specifically, the CPU sets α to a positive constant and determines whether 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 Tsoff stored in the storage device 50A, or is larger than the sum of the absolute value of the midpoint offset Tsoff and α. If a negative determination is made, control proceeds to S60; if an affirmative determination is made, control proceeds to S50.

[0046] In S50 , the CPU stores the steering torque Ts in the storage device 50A as the midpoint offset Tsoff of the steering torque sensor.

[0047] In S60 , the CPU increments by 1 the count value N indicating the number of times the midpoint shift amount has been detected.

[0048] In S70 , the CPU determines whether the count value N is greater than or equal to a reference value Nc (for example, a positive constant integer such as 3). If the CPU makes a negative determination, the control returns to S10 , and if the CPU makes an affirmative determination, the control ends. Midpoint Correction Control Routine of the First Embodiment

[0049] based on Figure 3 The midpoint correction control shown in the flowchart is Figure 1 When the ignition switch (not shown) is turned on, the CPU of the driving assistance ECU 50 repeatedly executes the control at predetermined intervals. Figure 3 The midpoint correction control in the flowchart shown may be repeatedly executed by the CPU of the EPS·ECU 40 at predetermined time intervals.

[0050] First, in S110, similar to S10, the CPU determines whether remote driving control is in progress. Furthermore, the vehicle 102 may be in either a driving state or a stationary state. If a positive determination is made, this control is temporarily terminated. If a negative determination is made, this control proceeds to S120.

[0051] In 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 Tsoff from the storage device 50A.

[0052] In S130 , the CPU outputs the value Ts-Tsoff obtained by subtracting the midpoint offset Tsoff from the steering torque Ts as the corrected steering torque Ts. The corrected steering torque Ts can be used in various driving assistance controls of the vehicle 102 in addition to the control of the steering assist torque. Second embodiment

[0053] In the second embodiment, the ROM of the steering assist ECU 50 stores the Figure 4 and Figure 3 The flowcharts shown correspond to a program for detecting and controlling the center point offset of the steering torque sensor and a program for controlling the center point correction of the steering torque sensor. The CPU executes the center point offset detection and control of the steering torque sensor and the center point correction control of the steering torque sensor according to these programs. The center point correction control of the steering torque sensor is similar to the center point correction control of the steering torque sensor in the first embodiment, so a description of this control is omitted. Midpoint shift amount detection control routine of the second embodiment

[0054] In the second embodiment, when an affirmative determination is made in S10, the control proceeds to S20. Figure 4 and Figure 2 As can be seen from the comparison, steps other than S20 are performed in the same manner as in the first embodiment.

[0055] In S20, the CPU outputs a command signal to the EPS / ECU 40, 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 such a magnitude that it does not steer the front wheels 16FL and 16FR, and is capable of relieving 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. Third embodiment

[0056] In the third embodiment, although Figure 1 Although not shown in FIG, the camera sensor 52 includes a driver monitoring camera that captures the driver's seat from the front to the rear, in addition to the camera that captures the surroundings of the vehicle 102. Figure 1 Although not shown in the figure, 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 held by the driver's hands.

[0057] Furthermore, in the third embodiment, the ROM of the steering assist ECU 50 stores the Figure 5 and Figure 3 The flowcharts shown correspond to a program for detecting and controlling the center point offset of the steering torque sensor and a program for controlling the center point correction of the steering torque sensor. The CPU executes the center point offset detection and control of the steering torque sensor and the center point correction control of the steering torque sensor according to these programs. The center point correction control of the steering torque sensor is similar to the center point correction control of the steering torque sensor in the first embodiment, so a description of this control is omitted. Midpoint shift amount detection control routine of the third embodiment

[0058] In the third embodiment, when an affirmative determination is made in S10, the control proceeds to S12. Figure 5 and Figure 2 As can be seen from the comparison, steps other than S12 and S14 are performed in the same manner as in the first embodiment.

[0059] In S12, the CPU determines whether the driver is sitting in the driver's seat in the vehicle 102 based on the result of analyzing the image captured by the driver monitoring camera. If a negative determination is made, the control proceeds to S30, and if a positive determination is made, the control proceeds to S14.

[0060] In S14, the CPU determines based on the detection result of the touch sensor whether the driver's hand is holding the steering wheel 14. If the determination is affirmative, the control returns to S10, and if the determination is negative, the control proceeds to S30.

[0061] As will be apparent from the above description, according to each embodiment, while remote control of the vehicle is in progress (S10), the steering torque Ts detected by the steering torque sensor 38 is stored in the non-volatile storage device 50A as the steering torque sensor's midpoint offset Tsoff. While remote control of the vehicle is in progress, the driver has exited the vehicle, so no torque is acting on the steering transmission system 34 or the steering torque sensor 38. Therefore, even when no torque is acting on the steering torque sensor, the steering torque detected by the steering torque sensor can be stored in the non-volatile storage device as the accurate midpoint offset of the steering torque sensor.

[0062] Furthermore, the midpoint offset is read from the storage device while the vehicle is traveling, and the steering torque Ts detected by the steering torque sensor is corrected using the midpoint offset Tsoff. Therefore, the steering torque detected by the steering torque sensor can be corrected using the accurate midpoint offset while the vehicle is traveling.

[0063] In addition, according to each embodiment, the remote driving control includes at least one of the remote parking control, the automatic valet parking control, and the smart summon control, so the accurate midpoint offset of the steering torque sensor 38 can be obtained while the control of at least one of them is in progress.

[0064] In particular, according to the first and second embodiments, the vehicle only needs to be remotely controlled, and no special device such as a camera that captures the driver's image in order to detect a situation where no torque is acting on the steering shaft 22 is required.

[0065] 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 the steering torque Ts detected by the steering torque sensor 38 is then stored in the storage device 50A as the midpoint offset Tsoff of the steering torque sensor. Therefore, compared to a case where no vibration torque is applied to the steering transmission system, the possibility of the midpoint offset being adversely affected by the torque remaining in the steering transmission system is reduced, and the midpoint offset can be determined more accurately.

[0066] The present invention has been described in detail above with reference to specific embodiments. However, the present invention is not limited to the above-described embodiments, and it is obvious to those skilled in the art that various other embodiments can be implemented within the scope of the present invention.

[0067] For example, in each of the above-described embodiments, whether or not the steering torque sensor midpoint offset Tsoff needs to be updated is determined in S40 based on the steering torque Ts detected by the steering torque sensor 38 and read in S30. However, the steering torque used for the determination in S40 may alternatively be the average value of the steering torque Ts read in S30 during a predetermined control cycle.

[0068] In the above embodiment, in S60, the count value N indicating the number of midpoint offset detections is incremented by 1. In S70, a determination is made as to whether the count value N is greater than or equal to a reference value Nc. If a negative determination is made, control returns to S10. However, S60 and S70 may be omitted, and S30 to S50 may be repeatedly executed while remote driving control is in effect.

[0069] In the second embodiment, in S20, the EPS device 12 applies a vibration torque to the steering shaft 22 of the steering transmission system 34, and then in S30, the steering torque Ts detected by the steering torque sensor 38 is read. However, S20 may be executed when a positive determination is made for the first time in S10, and when a positive determination is made for the second or subsequent times in S10, S20 may be skipped and the control may proceed to S30 without executing S20.

[0070] In the third embodiment, if it is determined in S12 that the driver is seated in the driver's seat, a determination is made in S14 as to whether the driver's hands are holding the steering wheel 14. If this determination is negative, the control proceeds to S30. However, either S12 or S14 may be omitted. Furthermore, if S14 is omitted, if a positive determination is made in S12, the control returns to S10; if a negative determination is made, the control proceeds to S30.

[0071] Furthermore, in the third embodiment, S20 is not performed. However, in the third embodiment, S20 may be performed.

Claims

1. A midpoint correction device for a steering torque sensor, adapted for use in a vehicle comprising: a torque application device for applying a control torque to a steering transmission system between a steering wheel and a steering wheel; and a steering torque sensor disposed in the steering transmission system between the steering wheel and the torque application device, wherein the midpoint correction device is configured to perform midpoint correction of the steering torque sensor, wherein: The midpoint correction device includes a control unit for remote driving control of the vehicle by communicating with a terminal device. The control unit includes a non-volatile storage device and is configured to store the steering torque detected by the steering torque sensor as the midpoint offset of the steering torque sensor in the storage device when the remote driving control is being performed, read the midpoint offset from the storage device when the vehicle is traveling, and use the midpoint offset to correct the steering torque detected by the steering torque sensor, thereby performing the midpoint correction.

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

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

4. A method for midpoint correction of a steering torque sensor, the method being applicable to a vehicle comprising: a torque application device for applying a control torque to a steering transmission system between a steering wheel and a steering wheel; and a steering torque sensor disposed in the steering transmission system between the steering wheel and the torque application device, wherein midpoint correction of the steering torque sensor is performed, The midpoint correction method includes: a step of storing the steering torque detected by the steering torque sensor as the midpoint offset of the steering torque sensor in a non-volatile storage device when remote driving control of the vehicle is being performed through communication with a terminal device; and a step of reading the midpoint offset from the storage device while the vehicle is traveling and using the midpoint offset to correct the steering torque detected by the steering torque sensor.

5. A midpoint calibration program for a steering torque sensor, the program being applicable to a vehicle comprising: a torque application device for applying a control torque to a steering transmission system between a steering wheel and a steering wheel; and a steering torque sensor disposed in the steering transmission system between the steering wheel and the torque application device, the midpoint calibration program causing an electronic control unit mounted on the vehicle to execute midpoint calibration of the steering torque sensor, wherein: The midpoint correction program causes the electronic control device to execute the following steps: storing the steering torque detected by the steering torque sensor as the midpoint offset of the steering torque sensor in a non-volatile storage device when the vehicle is being remotely driven and controlled by communicating with a terminal device; and reading the midpoint offset from the storage device while the vehicle is traveling and using the midpoint offset to correct the steering torque detected by the steering torque sensor.

Images