Yaw Rate Calibrator

Abstract

To easily calibrate a zero point of a yaw rate sensor.SOLUTION: A yaw rate calibration device 1 includes: a lateral position acquisition unit 12 that acquires a lateral position LP of a vehicle 2 relative to a target traveling position TP of a traveling lane TL in which the vehicle 2 travels; a driver steering torque acquisition unit 13 that acquires driver steering torque input by a driver; and a zero-point calibration unit 15 that calibrates a zero point of a yaw rate sensor 3. The zero-point calibration unit 15 calibrates the zero point of the yaw rate sensor 3, based on the lateral position LP acquired by the lateral position acquisition unit 12 and the driver steering torque acquired by the driver steering torque acquisition unit 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a yaw rate calibration device. [Background technology]

[0002] Patent Document 1 describes a steering control device that prevents a vehicle from running off the road by applying a steering assist torque to a steering means according to the deviation between an actual yaw rate and a reference yaw rate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-263794 Summary of the Invention [Problem to be solved by the invention]

[0004] In the steering control device described in Patent Document 1, the actual yaw rate is detected by a yaw rate sensor. The yaw rate sensor has a tendency to have its zero point drift due to temperature changes, the passage of time, etc. For this reason, the zero point of the yaw rate sensor has conventionally been calibrated using the value of the yaw rate sensor when the vehicle is stopped as a reference.

[0005] However, since the vehicle needs to be stopped to calibrate the zero point, this method is not necessarily convenient.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a yaw rate calibration device that can easily calibrate the zero point of a yaw rate sensor. [Means for solving the problem]

[0007] The yaw rate calibration device according to the present invention includes a lateral position acquisition unit that acquires the lateral position of the vehicle relative to a target driving position of the driving lane in which the vehicle is traveling, a driver steering torque acquisition unit that acquires a driver steering torque input by the driver, and a zero point calibration unit that calibrates the zero point of the yaw rate sensor, and the zero point calibration unit calibrates the zero point of the yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit.

[0008] The relationship between the lateral position of the vehicle and the driver's steering torque is different when the zero point of the yaw rate sensor is drifting compared to when the zero point of the yaw rate sensor is not drifting. Therefore, this yaw rate calibration device calibrates the zero point of the yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver's steering torque acquired by the driver steering torque acquisition unit. This eliminates the need to stop the vehicle to calibrate the zero point of the yaw rate sensor, and also allows the zero point of the yaw rate sensor to be calibrated automatically, making it possible to easily calibrate the zero point of the yaw rate sensor.

[0009] The yaw rate calibration device may further include a steering control unit that controls the steering of the vehicle so that the vehicle travels along the target travel position. In this yaw rate calibration device, the steering control unit controls the steering of the vehicle so that the vehicle travels along the target travel position, so that the zero point of the yaw rate sensor can be appropriately calibrated.

[0010] When the relationship between the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit differs from the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift, the zero point calibration unit may calibrate the zero point of the yaw rate sensor so that the relationship between the lateral position and the driver steering torque approaches the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift. When the zero point of the yaw rate sensor does not drift, the relationship between the lateral position of the vehicle and the driver steering torque becomes a predetermined relationship. Therefore, in this yaw rate calibration device, when the relationship between the lateral position and the driver steering torque differs from the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift, the zero point of the yaw rate sensor is calibrated so that the relationship between the lateral position and the driver steering torque approaches the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift. This allows the zero point of the yaw rate sensor to be appropriately calibrated.

[0011] The zero point calibration unit may calibrate the zero point of the yaw rate sensor in the direction of the driver's steering torque when the direction of the lateral position relative to the target driving position differs from the direction of the driver's steering torque. When the direction of the lateral position relative to the target driving position differs from the direction of the driver's steering torque, it is considered that the vehicle is traveling at a position offset from the target driving position due to drift of the zero point of the yaw rate sensor, and the driver is trying to return it to the target driving position. Therefore, with this yaw rate calibration device, when the direction of the lateral position relative to the target driving position differs from the direction of the driver's steering torque, the zero point of the yaw rate sensor can be calibrated appropriately.

[0012] The zero point calibration unit may calibrate the zero point of the yaw rate sensor in the direction of the driver's steering torque when the lateral position exceeds either the left or right threshold distance and the driver's steering torque exceeds either the left or right threshold torque. When the lateral position exceeds either the left or right threshold distance and the driver's steering torque exceeds either the left or right threshold torque, it is considered that the vehicle is traveling at a position offset from the target traveling position due to drift of the zero point of the yaw rate sensor, and the driver is trying to return the vehicle to the target traveling position. Therefore, with this yaw rate calibration device, when the lateral position exceeds either the left or right threshold distance and the driver's steering torque exceeds the other left or right threshold torque, the zero point of the yaw rate sensor is calibrated in the direction of the driver's steering torque, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor.

[0013] The zero point calibration unit may calibrate the zero point of the yaw rate sensor in the direction of the driver's steering torque when the lateral position is located in a central region not exceeding the left and right threshold distances and the driver's steering torque exceeds the left and right threshold torques. When the lateral position is located in a central region not exceeding the left and right threshold distances and the driver's steering torque exceeds the left and right threshold torques, it is considered that the vehicle is attempting to travel at a position offset from the target traveling position due to drift of the zero point of the yaw rate sensor, and the driver is returning the vehicle to the target traveling position. Therefore, with this yaw rate calibration device, when the lateral position is located in a central region not exceeding the left and right threshold distances and the driver's steering torque exceeds the left and right threshold torques, the zero point of the yaw rate sensor is calibrated in the direction of the driver's steering torque, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor.

[0014] The zero point calibration unit may calibrate the zero point of the yaw rate sensor in the direction of the lateral position relative to the target driving position when the lateral position exceeds either the left or right threshold distance and the driver steering torque does not exceed the left or right threshold torque. When the lateral position exceeds either the left or right threshold distance and the driver steering torque does not exceed the left or right threshold torque, it is considered that the vehicle is traveling at a position offset from the target driving position due to drift of the zero point of the yaw rate sensor, but the driver is unaware that the vehicle is traveling at a position offset from the target driving position. Therefore, with this yaw rate calibration device, when the lateral position exceeds either the left or right threshold distance and the driver steering torque does not exceed the left or right threshold torque, the zero point of the yaw rate sensor is calibrated in the direction of the lateral position relative to the target driving position, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor.

[0015] The zero point calibration unit may calibrate the zero point of the yaw rate sensor based on an average value of multiple lateral positions acquired by the lateral position acquisition unit at a first set time and an average value of multiple driver steering torques acquired by the driver steering torque acquisition unit at a second set time. In this yaw rate calibration device, the zero point of the yaw rate sensor is calibrated based on the average value of the lateral positions at the first set time and the average value of the driver steering torque at the second set time, so that even if a sudden disturbance is input to the lateral position acquisition unit and the driver steering torque acquisition unit, a decrease in calibration accuracy can be suppressed.

[0016] The zero point calibration unit may calibrate the zero point of the yaw rate sensor in stages. In this yaw rate calibration device, by calibrating the zero point of the yaw rate sensor in stages, it is possible to make the change in vehicle behavior due to the calibration gentle.

[0017] The yaw rate calibration device may further include a curvature acquisition unit that acquires the curvature of the driving lane, and the zero point calibration unit may change a calibration value for calibrating the zero point of the yaw rate sensor according to the curvature acquired by the curvature acquisition unit. This yaw rate calibration device can calculate a target driving position with high accuracy by acquiring the curvature of the driving lane with the curvature acquisition unit. However, the curvature acquisition unit may erroneously recognize the curvature due to an error in the installation position on the vehicle, etc. Furthermore, such erroneous recognition may vary significantly depending on the curvature of the driving lane. Therefore, this yaw rate calibration device can suppress a decrease in calibration accuracy due to erroneous recognition by the curvature acquisition unit by changing a calibration value for calibrating the zero point of the yaw rate sensor according to the curvature acquired by the curvature acquisition unit.

[0018] The zero-point calibration unit may set the calibration value to a first calibration value when the curvature is in a linear region between a first right threshold curvature and a first left threshold curvature, change the calibration value from the first calibration value to a second calibration value when the curvature in the linear region exceeds the first right threshold curvature, change the calibration value from the second calibration value to the first calibration value when the curvature subsequently exceeds a second right threshold curvature that is closer to zero than the first right threshold curvature, change the calibration value from the first calibration value to a third calibration value when the curvature in the linear region exceeds the second right threshold curvature, and change the calibration value from the third calibration value to the first calibration value when the curvature subsequently exceeds a second left threshold curvature that is closer to zero than the first left threshold curvature. In this yaw rate calibration device, frequent changes in the calibration value can be suppressed by providing hysteresis characteristics to the relationship between the curvature and the calibration value.

[0019] The zero point calibration unit does not need to calibrate the zero point of the yaw rate sensor until a set time has elapsed since the zero point of the yaw rate sensor was calibrated. It takes a certain amount of time for the vehicle to reach the target driving position after calibrating the zero point of the yaw rate sensor. Therefore, if the zero point of the yaw rate sensor is further calibrated between the time when the zero point of the yaw rate sensor was calibrated and the time when the vehicle reaches the target driving position, the zero point of the yaw rate sensor may not be properly calibrated. Therefore, this yaw rate calibration device does not calibrate the zero point of the yaw rate sensor until the set time has elapsed since the zero point of the yaw rate sensor was calibrated, so that the zero point of the yaw rate sensor can be properly calibrated. [Effects of the Invention]

[0020] According to the present invention, the zero point of the yaw rate sensor can be easily calibrated. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram illustrating a yaw rate calibration device according to an embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a situation in which a vehicle is traveling in a traffic lane. [Figure 3] FIG. 2 is a schematic diagram for explaining an example of the direction of a driver steering torque input to a steering wheel. [Figure 4] FIG. 1 is a schematic diagram showing an example of a situation in which a vehicle is traveling in a curved driving lane. [Figure 5] 10 is a table showing an example of the relationship between lateral position and driver steering torque. [Figure 6] 10 is a graph showing an example of the relationship between time and a calibration amount. [Figure 7] 10 is a table showing an example of the relationship between the curvature of a driving lane and a calibration value. [Figure 8] 10 is a flowchart showing an example of a processing operation of the yaw rate calibration device. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted.

[0023] FIG. 1 is a schematic diagram showing a yaw rate calibration device 1 according to an embodiment. As shown in FIG. 1, the yaw rate calibration device 1 according to this embodiment is mounted on a vehicle 2 and calibrates the zero point of a yaw rate sensor 3 mounted on the vehicle 2. The yaw rate calibration device 1 is, for example, an electronic control unit (ECU) having a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), etc. The yaw rate calibration device 1 performs various controls by, for example, loading a program stored in the ROM into the RAM and executing the program on the CPU. The yaw rate calibration device 1 may be configured by a single electronic control unit or multiple electronic control units.

[0024] The yaw rate calibration device 1 includes a steering control unit 11, a lateral position acquisition unit 12, a driver steering torque acquisition unit 13, a curvature acquisition unit 14, and a zero point calibration unit 15.

[0025] FIG. 2 is a schematic diagram showing an example of a situation in which the vehicle 2 is traveling on a traveling lane TL. As shown in FIGS. 1 and 2, the steering control unit 11 performs steering control of the vehicle 2 so that the vehicle 2 travels at a target traveling position TP. The steering control unit 11 performs steering control of the vehicle 2 by driving and controlling a steering actuator (not shown) that applies steering torque to the steering wheel 4 (see FIG. 3). In other words, the steering control of the vehicle 2 is performed by driving and controlling the steering actuator. Then, the steering control unit 11 performs steering control of the vehicle 2 so that the vehicle 2 travels at a target traveling position TP on the traveling lane TL. The target traveling position TP is a position in the lane width direction of the traveling lane TL, for example, the center of the lane width direction of the traveling lane TL. The method of steering control of the vehicle 2 is not particularly limited. For example, the steering control unit 11 may perform steering control of the vehicle 2 by calculating the steering torque to be applied to the steering wheel 4 based on the difference between a target yaw rate required for the vehicle 2 to travel to a predetermined position in the travel lane TL and the current yaw rate of the vehicle 2, and driving and controlling the steering actuator with a drive amount corresponding to this calculated steering torque.

[0026] The lateral position acquisition unit 12 acquires the lateral position LP of the vehicle 2 relative to a target driving position TP of the driving lane TL on which the vehicle 2 is traveling. The lateral position LP of the vehicle 2 is the position of the vehicle 2 relative to the target driving position TP in the lane width direction of the driving lane TL. The position of the vehicle 2 can be, for example, the position of the center of gravity of the vehicle 2. The lateral position acquisition unit 12, for example, extracts a dividing line (white line) of the driving lane TL from an image captured by a camera (not shown), and acquires the position of the vehicle 2 based on the positional relationship between the extracted dividing line and the vehicle 2. The lateral position acquisition unit 12 also acquires the target driving position TP, which serves as a reference for steering control of the vehicle 2, from the steering control unit 11. The lateral position acquisition unit 12 then acquires the lateral position LP of the vehicle 2 based on the position of the vehicle 2 and the target driving position TP. For example, the lateral position acquisition unit 12 considers a lateral position LP on the right side relative to the target driving position TP to be negative, and a lateral position LP on the left side relative to the target driving position TP to be positive.

[0027] The driver steering torque acquisition unit 13 acquires the driver steering torque input by the driver. A steering torque obtained by combining the control steering torque input by the steering actuator and the driver steering torque input to the steering 4 by the driver to steer the vehicle 2 is input to the steering 4. The control steering torque is a torque input to the steering 4 by the steering actuator whose drive is controlled by the steering control unit 11. The control steering torque can be calculated from the control value of the steering control unit 11. The steering torque can be calculated by a torque sensor directly or indirectly connected to the steering 4. Therefore, the driver steering torque acquisition unit 13 acquires, as the driver steering torque, a torque obtained by subtracting the control steering torque from the steering torque. In other words, the driver steering torque acquired by the driver steering torque acquisition unit 13 is not the actual torque input to the steering 4 by the driver to steer the vehicle 2, but is a torque estimated to have been input to the steering 4 by the driver to steer the vehicle 2 (an estimated value of the driver steering torque). However, if it is possible to directly acquire the driver steering torque, the driver steering torque may be acquired directly rather than as an estimated value. Fig. 3 is a schematic diagram for explaining an example of the direction of the driver steering torque input to the steering wheel 4. As shown in Fig. 3, the driver steering torque acquisition unit 13, for example, regards the driver steering torque in the right steering direction (right turning direction) as positive and the driver steering torque in the left steering direction (left turning direction) as negative.

[0028] 1 and 2, the curvature acquisition unit 14 acquires the curvature of the driving lane TL. For example, the curvature acquisition unit 14 extracts the dividing lines (white lines) of the driving lane TL from an image captured by a camera, calculates a reference line that passes through the center of the driving lane TL in the lane width direction from the extracted dividing lines, and calculates the curvature of the calculated reference line to acquire the curvature of the driving lane TL. The curvature of the driving lane TL is used, for example, to calculate a target yaw rate that serves as a reference for steering control of the vehicle 2 by the steering control unit 11. For example, the curvature acquisition unit 14 sets the curvature of the driving lane TL on a right curve to be negative and the curvature of the driving lane TL on a left curve to be positive.

[0029] The zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3. The yaw rate sensor 3 is a sensor that detects the yaw rate of the vehicle 2. The yaw rate detected by the yaw rate sensor 3 is used, for example, for steering control by the steering control unit 11. The zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 based on the lateral position LP acquired by the lateral position acquisition unit 12 and the driver steering torque acquired by the driver steering torque acquisition unit 13.

[0030] 4 is a schematic diagram showing an example of a situation in which the vehicle 2 is traveling on a curved driving lane TL. As shown in FIG. 4, when the steering control unit 11 performs steering control of the vehicle 2 so that the vehicle 2 travels to the target traveling position TP, if the zero point of the yaw rate sensor 3 has not drifted, the vehicle 2 travels along the target traveling position TP. However, if the zero point of the yaw rate sensor 3 has drifted, the vehicle 2 travels at a position offset from the target traveling position TP. For example, if the zero point of the yaw rate sensor 3 has drifted to the left turning side, the vehicle 2 travels at a position to the left of the target traveling position TP, and if the zero point of the yaw rate sensor 3 has drifted to the right turning side, the vehicle 2 travels at a position to the right of the target traveling position TP.

[0031] If the relationship between the lateral position LP acquired by the lateral position acquisition unit 12, the driver steering torque acquired by the driver steering torque acquisition unit 13, and DT differs from the relationship between the lateral position LP and the driver steering torque when the zero point of the yaw rate sensor 3 has not drifted, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 in a direction in which the relationship between the lateral position LP and the driver steering torque approaches the relationship between the lateral position LP and the driver steering torque when the zero point of the yaw rate sensor 3 has not drifted.

[0032] For example, if the direction of the lateral position LP relative to the target traveling position TP differs from the direction of the driver's steering torque, it is considered that the vehicle 2 is traveling at a position offset from the target traveling position TP due to drift of the zero point of the yaw rate sensor 3, and the driver is trying to return it to the target traveling position TP. Therefore, when the direction of the lateral position LP relative to the target traveling position TP differs from the direction of the driver's steering torque, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 in the direction of the driver's steering torque. The calibration direction of the zero point of the yaw rate sensor 3 is the turning direction corresponding to the direction of the driver's steering torque. For example, if the driver's steering torque is in the right steering direction, the zero point of the yaw rate sensor 3 is calibrated to the right turning direction.

[0033] Furthermore, for example, when the lateral position LP exceeds either the left or right threshold distance and the driver steering torque exceeds either the left or right threshold torque, it is considered that the vehicle 2 is traveling at a position offset from the target traveling position TP due to drift of the zero point of the yaw rate sensor 3, and the driver is trying to return it to the target traveling position TP. Therefore, when the lateral position LP exceeds either the left or right threshold distance and the driver steering torque exceeds either the left or right threshold torque, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 in the direction of the driver steering torque. The calibration direction of the zero point of the yaw rate sensor 3 is the turning direction corresponding to the direction of the driver steering torque. For example, when the driver steering torque is in the right steering direction, the zero point of the yaw rate sensor 3 is calibrated in the right turning direction.

[0034] Furthermore, for example, if the lateral position LP exceeds either the left or right threshold distance and the driver steering torque exceeds either the left or right threshold torque, it is considered that the vehicle 2 is traveling at a position offset from the target traveling position TP due to drift of the zero point of the yaw rate sensor 3, and the driver is trying to return it to the target traveling position TP. Therefore, when the lateral position LP is located in a central region that does not exceed the left or right threshold distance and the driver steering torque exceeds the left or right threshold torque, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 in the direction of the driver steering torque. The calibration direction of the zero point of the yaw rate sensor 3 is the turning direction corresponding to the direction of the driver steering torque. For example, when the driver steering torque is in the right steering direction, the zero point of the yaw rate sensor 3 is calibrated to the right turning direction.

[0035] Furthermore, for example, if the lateral position LP exceeds either the left or right threshold distance and the driver's steering torque does not exceed the left or right threshold torque, it is considered that the vehicle 2 is traveling at a position offset from the target traveling position TP due to drift of the zero point of the yaw rate sensor 3, but the driver is unaware that the vehicle 2 is traveling at a position offset from the target traveling position TP. Therefore, when the lateral position LP exceeds either the left or right threshold distance and the driver's steering torque does not exceed the left or right threshold torque, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 to the direction of the lateral position LP relative to the target traveling position TP. The calibration direction of the zero point of the yaw rate sensor 3 is the turning direction corresponding to the lateral position LP relative to the target traveling position TP. For example, if the lateral position LP is located to the right of the target traveling position TP, the zero point of the yaw rate sensor 3 is calibrated to the right turning direction.

[0036] FIG. 5 is a table showing an example of the relationship between the lateral position LP and the driver steering torque. In FIG. 5, the lateral position LP is divided into three regions: a left region, a center region, and a right region. The left region is a region where the lateral position LP exceeds the left threshold distance, i.e., a region where the lateral position LP is located to the left of the left threshold distance. The center region is a region where the lateral position LP does not exceed the left or right threshold distance. The right region is a region where the lateral position LP exceeds the right threshold distance, i.e., a region where the lateral position LP is located to the right of the right threshold distance. The left threshold distance is a predetermined distance located to the left of the target traveling position TP, and can be, for example, +0.2 m. The right threshold distance is a predetermined distance located to the right of the target traveling position TP, and can be, for example, -0.2 m.

[0037] In addition, in FIG. 5, the driver steering torque is divided into three regions: a left steering region, a no-steering region, and a right steering region. The left steering region is a region where the driver steering torque exceeds a left threshold torque, that is, a region where the driver steering torque is larger in the left steering direction than the left threshold torque. The no-steering region is a region where the driver steering torque does not exceed the left or right threshold torque. The right steering region is a region where the driver steering torque exceeds a right threshold torque, that is, a region where the driver steering torque is larger in the right steering direction than the right threshold torque. The left threshold torque is a torque where the driver steering torque is in the left steering direction and can be set to, for example, −0.2 Nm. The right threshold torque is a torque where the driver steering torque is in the right steering direction and can be set to, for example, +0.2 Nm.

[0038] As shown in FIG. 5, when the zero point of the yaw rate sensor 3 does not drift, the relationship between the lateral position LP and the target traveling position TP is one of the relationships indicated by the crosses in FIG. 5: "left side area-left steering area," "center area-no steering area," and "right side area-right steering area."

[0039] When the relationship is "left side area-left steering area", the driver wants to drive the vehicle 2 to the left of the target driving position TP, and therefore it is considered that the driver is inputting driver steering torque in the left steering direction to the steering wheel 4. When the relationship is "center area-no steering area", the driver wants to drive the vehicle 2 at or near the target driving position TP, and therefore it is considered that the driver is not inputting driver steering torque or is inputting very little driver steering torque to the steering wheel 4. When the relationship is "right side area-right steering area", the driver wants to drive the vehicle 2 to the right of the target driving position TP, and therefore it is considered that the driver is inputting driver steering torque in the right steering direction to the steering wheel 4.

[0040] On the other hand, when the zero point of the yaw rate sensor 3 is drifting, the relationship between the lateral position LP and the target driving position TP becomes one of the relationships indicated by circles in FIG. 5, namely, "right side area-left steering area," "left side area-right steering area," "center area-left steering area," "center area-right steering area," "right side area-no steering area," and "left side area-no steering area."

[0041] When the relationship is "right side area - left steering area", the vehicle 2 has been traveling significantly to the right of the target traveling position TP, and therefore it is considered that the driver is inputting driver steering torque in the left steering direction to the steering wheel 4 to return the vehicle 2 to the target traveling position TP. When the relationship is "left side area - right steering area", the vehicle 2 has been traveling significantly to the left of the target traveling position TP, and therefore it is considered that the driver is inputting driver steering torque in the right steering direction to the steering wheel 4 to return the vehicle 2 to the target traveling position TP.

[0042] When the relationship is "center area-left steering area", the vehicle 2 is attempting to travel to the right of the target driving position TP, and therefore it is considered that the driver is inputting driver steering torque in the left steering direction to the steering wheel 4 to return the vehicle 2 to the target driving position TP. When the relationship is "center area-right steering area", the vehicle 2 is attempting to travel to the left of the target driving position TP, and therefore it is considered that the driver is inputting driver steering torque in the right steering direction to the steering wheel 4 to return the vehicle 2 to the target driving position TP.

[0043] When the relationship is "right side area-no steering area", it is considered that the vehicle 2 is traveling to the right of the target traveling position TP, but the driver is unaware that the vehicle 2 is traveling to the right of the target traveling position TP, or the driver wants the vehicle 2 to travel to the right of the target traveling position TP, and so the driver is not inputting or is barely inputting driver steering torque to the steering wheel 4. When the relationship is "left side area-no steering area", it is considered that the driver is unaware that the vehicle 2 is traveling to the left of the target traveling position TP, or the driver is traveling to the left of the target traveling position TP, but the driver wants the vehicle 2 to travel to the left of the target traveling position TP, and so the driver is not inputting or is barely inputting driver steering torque to the steering wheel 4.

[0044] Therefore, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 when the relationship between the lateral position LP and the target driving position TP is any one of the relationships indicated by circles in FIG. 5: "right side area-left steering area," "left side area-right steering area," "center area-left steering area," "center area-right steering area," "right side area-no steering area," and "left side area-no steering area."

[0045] When the relationship between the lateral position LP and the target driving position TP is "right side area-left steering area," the zero point of the yaw rate sensor 3 is calibrated to the left turning direction corresponding to the direction of the driver's steering torque. When the relationship between the lateral position LP and the target driving position TP is "left side area-right steering area," the zero point of the yaw rate sensor 3 is calibrated to the right turning direction corresponding to the direction of the driver's steering torque.

[0046] When the relationship between the lateral position LP and the target driving position TP is "center area-left steering area," the zero point of the yaw rate sensor 3 is calibrated to the left turning direction corresponding to the direction of the driver's steering torque. When the relationship between the lateral position LP and the target driving position TP is "center area-right steering area," the zero point of the yaw rate sensor 3 is calibrated to the right turning direction corresponding to the direction of the driver's steering torque.

[0047] When the relationship between the lateral position LP and the target traveling position TP is "right side area-no steering area," the zero point of the yaw rate sensor 3 is calibrated to the right turning direction corresponding to the direction of the lateral position LP relative to the target traveling position TP. When the relationship between the lateral position LP and the target traveling position TP is "left side area-no steering area," the zero point of the yaw rate sensor 3 is calibrated to the left turning direction corresponding to the direction of the lateral position LP relative to the target traveling position TP.

[0048] The zero point calibration unit 15 may calibrate the zero point of the yaw rate sensor based on one lateral position LP most recently acquired by the lateral position acquisition unit 12 and one driver steering torque most recently acquired by the driver steering torque acquisition unit 13. However, it is preferable to calibrate the zero point of the yaw rate sensor based on an average value of multiple lateral positions LP acquired by the lateral position acquisition unit 12 at a first set time and an average value of multiple driver steering torques acquired by the driver steering torque acquisition unit 13 at a second set time. That is, it is preferable that the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 by setting the average value of the multiple lateral positions LP acquired by the lateral position acquisition unit 12 at the first set time as the lateral position LP acquired by the lateral position acquisition unit 12 and setting the average value of multiple driver steering torques acquired by the driver steering torque acquisition unit 13 at the second set time as the driver steering torque acquired by the driver steering torque acquisition unit 13. The first set time and the second set time are not particularly limited, but are preferably the first set time and the second set time immediately before the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor. The first and second set times may be the same or different. For example, the first and second set times may each be 10 seconds.

[0049] Fig. 6 is a graph showing an example of the relationship between time and the calibration amount. The calibration amount is an integrated value obtained by accumulating the calibration values ​​used to calibrate the zero point of the yaw rate sensor 3 from the start of calibration of the zero point of the yaw rate sensor 3 to the end of calibration of the zero point of the yaw rate sensor 3. When calibrating the zero point of the yaw rate sensor 3, the zero point calibration unit 15 may perform the calibration all at once, but it is preferable to calibrate the zero point of the yaw rate sensor 3 in stages, as shown in Fig. 6. In other words, it is preferable for the zero point calibration unit 15 to calibrate the zero point of the yaw rate sensor 3 for each predetermined calibration value.

[0050] The calibration value for gradually calibrating the zero point of the yaw rate sensor 3 is not particularly limited, and may be a fixed value or a variable value. When the calibration value is a fixed value, the fixed value may be, for example, 0.002 [rad / s]. When the calibration value is a variable value, the calibration value may be varied depending on, for example, the curvature of the traveling lane TL. In other words, the zero point calibration unit 15 may calibrate the zero point of the yaw rate sensor 3 using a calibration value that varies depending on the curvature of the traveling lane TL. The curvature of the traveling lane TL can be acquired by the curvature acquisition unit 14.

[0051] When varying the calibration value according to the curvature of the driving lane TL, the curvature and the calibration value may correspond one-to-one, or a hysteresis characteristic may be provided, as shown in FIG. 7. FIG. 7 is a table showing an example of the relationship between the curvature of the driving lane TL and the calibration value. In FIG. 7, when the curvature of the driving lane TL is in a linear region between a first right threshold curvature and a first left threshold curvature, the calibration value is set to a first calibration value. Then, when the curvature of the driving lane TL, which was in the linear region, exceeds the first right threshold curvature, the calibration value is varied from the first calibration value to a second calibration value. Thereafter, when the curvature of the driving lane TL exceeds a second right threshold curvature, which is closer to zero than the first right threshold curvature, the calibration value is varied from the second calibration value to the first calibration value. Furthermore, when the curvature of the driving lane TL, which was in the straight region, exceeds a second right threshold curvature, the calibration value is changed from the first calibration value to a third calibration value, and thereafter, when the curvature of the driving lane TL exceeds a second left threshold curvature, which is closer to zero than the first left threshold curvature, the calibration value is changed from the third calibration value to the first calibration value. The first right threshold curvature, the second right threshold curvature, the first left threshold curvature, and the second left threshold curvature are not particularly limited. The first calibration value, the second calibration value, and the third calibration value are not particularly limited.

[0052] Furthermore, the zero point calibration unit 15 may continuously calibrate the zero point of the yaw rate sensor 3, but it takes a certain amount of time from when the zero point of the yaw rate sensor 3 is calibrated until the vehicle 2 reaches the target traveling position TP. For this reason, as shown in FIG. 6, it is preferable not to calibrate the zero point of the yaw rate sensor 3 until a set time has elapsed since the zero point of the yaw rate sensor 3 was calibrated. In other words, the zero point calibration unit 15 calibrates the zero point of the yaw rate sensor 3 at set time intervals. The set time is not particularly limited and can be, for example, 10 seconds.

[0053] Next, an example of the processing operation of the yaw rate calibration device 1 will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of the processing operation of the yaw rate calibration device 1.

[0054] 8, the yaw rate calibration device 1 acquires the lateral position LP and the driver steering torque (step S1). In step S1, the curvature of the driving lane TL may also be acquired.

[0055] Next, the yaw rate calibration device 1 determines whether it is necessary to calibrate the zero point of the yaw rate sensor 3 (step S2). In step S2, for example, by referring to the table in Fig. 5, if the relationship between the lateral position LP and the driver steering torque is different from the relationship between the lateral position LP and the driver steering torque when the zero point of the yaw rate sensor 3 has not drifted, it determines that it is necessary to calibrate the zero point of the yaw rate sensor 3. If it is determined that it is not necessary to calibrate the zero point of the yaw rate sensor 3 (step S2: NO), the yaw rate calibration device 1 ends the process once and repeats the process from step S1 again after a set time has elapsed.

[0056] On the other hand, when it is determined that the zero point of the yaw rate sensor 3 needs to be calibrated (step S2: YES), the yaw rate calibration device 1 calibrates the zero point of the yaw rate sensor 3 based on the lateral position LP and the driver steering torque acquired in step S1 (step S3). In step S3, for example, by referring to the table in Fig. 5, the zero point of the yaw rate sensor 3 is calibrated in a direction in which the relationship between the lateral position LP and the driver steering torque approaches the relationship between the lateral position LP and the driver steering torque when the zero point of the yaw rate sensor 3 has not drifted. Thereafter, the yaw rate calibration device 1 temporarily ends the processing, and after a set time has elapsed, repeats the processing from step S1 again.

[0057] As described above, in the yaw rate calibration device 1 according to this embodiment, since the relationship between the lateral position of the vehicle and the driver steering torque differs when the zero point of the yaw rate sensor is drifting and when the zero point of the yaw rate sensor is not drifting, the zero point of the yaw rate sensor 3 is calibrated based on the lateral position LP acquired by the lateral position acquisition unit 12 and the driver steering torque acquired by the driver steering torque acquisition unit 13. This eliminates the need to stop the vehicle 2 in order to calibrate the zero point of the yaw rate sensor 3, and also makes it possible to automatically calibrate the zero point of the yaw rate sensor 3, making it possible to easily calibrate the zero point of the yaw rate sensor 3.

[0058] Furthermore, in this yaw rate calibration device 1, the steering control unit 11 controls the steering of the vehicle 2 so that the vehicle 2 travels at the target traveling position TP, so that the zero point of the yaw rate sensor 3 can be calibrated appropriately.

[0059] Furthermore, in this yaw rate calibration device 1, when the relationship between the lateral position and the driver's steering torque differs from the relationship between the lateral position LP and the driver's steering torque when the zero point of the yaw rate sensor 3 does not drift, the zero point of the yaw rate sensor 3 is calibrated in a direction in which the relationship between the lateral position LP and the driver's steering torque approaches the relationship between the lateral position LP and the driver's steering torque when the zero point of the yaw rate sensor 3 does not drift. This makes it possible to appropriately calibrate the zero point of the yaw rate sensor 3.

[0060] Furthermore, in this yaw rate calibration device 1, when the direction of the lateral position LP relative to the target driving position TP differs from the direction of the driver's steering torque, the zero point of the yaw rate sensor 3 can be appropriately calibrated by calibrating the zero point of the yaw rate sensor 3 to the direction of the driver's steering torque.

[0061] Furthermore, in this yaw rate calibration device 1, when the lateral position LP exceeds either the left or right threshold distance and the driver steering torque exceeds either the left or right threshold torque, the zero point of the yaw rate sensor 3 is calibrated in the direction of the driver steering torque, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor 3.

[0062] Furthermore, in this yaw rate calibration device 1, when the lateral position LP is located in a central region that does not exceed the left and right threshold distances and the driver steering torque exceeds the left and right threshold torques, the zero point of the yaw rate sensor 3 is calibrated in the direction of the driver steering torque, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor 3.

[0063] Furthermore, in this yaw rate calibration device 1, when the lateral position LP exceeds either the left or right threshold distance and the driver steering torque does not exceed the left or right threshold torque, the zero point of the yaw rate sensor 3 is calibrated in the direction of the lateral position LP relative to the target driving position TP, thereby making it possible to appropriately calibrate the zero point of the yaw rate sensor 3.

[0064] Furthermore, in this yaw rate calibration device 1, the zero point of the yaw rate sensor 3 is calibrated based on the average value of the lateral position LP at a first set time and the average value of the driver steering torque at a second set time, so that even if a sudden disturbance is input to the lateral position acquisition unit 12 and the driver steering torque acquisition unit 13, it is possible to prevent a decrease in calibration accuracy.

[0065] Furthermore, in this yaw rate calibration device 1, by calibrating the zero point of the yaw rate sensor 3 in stages, it is possible to make the change in behavior of the vehicle 2 due to the calibration gentle.

[0066] Furthermore, in this yaw rate calibration device 1, the curvature of the driving lane TL is acquired by the curvature acquisition unit 14, thereby enabling the target driving position TP to be calculated with high accuracy. However, the curvature acquisition unit 14 may erroneously recognize the curvature due to an error in its installation position on the vehicle 2, etc. Furthermore, such erroneous recognition may vary significantly depending on the curvature of the driving lane TL. Therefore, in this yaw rate calibration device 1, a decrease in calibration accuracy due to erroneous recognition by the curvature acquisition unit 14 can be suppressed by changing the calibration value used to calibrate the zero point of the yaw rate sensor 3 in accordance with the curvature acquired by the curvature acquisition unit 14.

[0067] Furthermore, in this yaw rate calibrating device 1, by providing a hysteresis characteristic to the relationship between the curvature and the calibration value, it is possible to suppress frequent fluctuations in the calibration value.

[0068] Furthermore, in this yaw rate calibration device 1, the zero point of the yaw rate sensor 3 is not calibrated again until a set time has elapsed since the zero point of the yaw rate sensor 3 was calibrated, so that the zero point of the yaw rate sensor 3 can be calibrated appropriately.

[0069] The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and may be modified or applied to other things within the scope that does not change the gist described in each claim. [Explanation of symbols]

[0070] 1...yaw rate calibration device, 2...vehicle, 3...yaw rate sensor, 4...steering, 11...steering control unit, 12...lateral position acquisition unit, 13...driver steering torque acquisition unit, 14...curvature acquisition unit, 15...zero point calibration unit, LP...lateral position, TL...driving lane, TP...target driving position.

Claims

1. A lateral position acquisition unit that acquires a lateral position of a vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit, the zero point calibration unit calibrates the zero point of the yaw rate sensor to the direction of the driver steering torque when the direction of the lateral position with respect to the target traveling position differs from the direction of the driver steering torque. Yaw rate calibration device.

2. A lateral position acquisition unit that acquires a lateral position of the vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit, the zero point calibration unit calibrates the zero point of the yaw rate sensor in a direction of the driver steering torque when the lateral position exceeds one of the left and right threshold distances and the driver steering torque exceeds the other of the left and right threshold torques. Yaw rate calibration device.

3. A lateral position acquisition unit that acquires a lateral position of the vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit, the zero point calibration unit calibrates the zero point of the yaw rate sensor in a direction of the driver steering torque when the lateral position is located in a central region not exceeding a left or right threshold distance and the driver steering torque exceeds a left or right threshold torque; Yaw rate calibration device.

4. A lateral position acquisition unit that acquires a lateral position of the vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit, the zero point calibration unit calibrates the zero point of the yaw rate sensor in a direction of the lateral position relative to the target traveling position when the lateral position exceeds one of the left and right threshold distances and the driver steering torque does not exceed the left and right threshold torques. Yaw rate calibration device.

5. A lateral position acquisition unit that acquires a lateral position of the vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit, the zero point calibration unit calibrates the zero point of the yaw rate sensor in stages; Yaw rate calibration device.

6. A lateral position acquisition unit that acquires a lateral position of the vehicle relative to a target driving position of a driving lane in which the vehicle is traveling; a driver steering torque acquisition unit that acquires a driver steering torque input by a driver; a zero point calibration unit that calibrates a zero point of a yaw rate sensor based on the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit; a curvature acquisition unit that acquires the curvature of the driving lane, the zero point calibration unit changes a calibration value used to calibrate the zero point of the yaw rate sensor in accordance with the curvature acquired by the curvature acquisition unit. Yaw rate calibration device.

7. The zero point calibration unit if the curvature is in a linear region between a first right threshold curvature and a first left threshold curvature, the calibration value is a first calibration value; varying the calibration value from the first calibration value to a second calibration value when the curvature in the linear region exceeds the first right threshold curvature, and subsequently varying the calibration value from the second calibration value to the first calibration value when the curvature exceeds a second right threshold curvature that is closer to zero than the first right threshold curvature; changing the calibration value from the first calibration value to a third calibration value when the curvature in the linear region exceeds the second right threshold curvature, and thereafter changing the calibration value from the third calibration value to the first calibration value when the curvature exceeds a second left threshold curvature that is closer to zero than the first left threshold curvature; 7. The yaw rate calibration device according to claim 6.

8. a steering control unit that controls the steering of the vehicle so that the vehicle travels to a target travel position; The yaw rate calibration device according to any one of claims 1 to 7.

9. When the relationship between the lateral position acquired by the lateral position acquisition unit and the driver steering torque acquired by the driver steering torque acquisition unit differs from the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift, the zero point calibration unit calibrates the zero point of the yaw rate sensor in a direction in which the relationship between the lateral position and the driver steering torque approaches the relationship between the lateral position and the driver steering torque when the zero point of the yaw rate sensor does not drift. The yaw rate calibration device according to any one of claims 1 to 8.

10. the zero point calibration unit calibrates the zero point of the yaw rate sensor based on an average value of the plurality of lateral positions acquired by the lateral position acquisition unit at a first set time and an average value of the plurality of driver steering torques acquired by the driver steering torque acquisition unit at a second set time. The yaw rate calibration device according to any one of claims 1 to 9.

11. the zero point calibration unit does not calibrate the zero point of the yaw rate sensor again until a set time has elapsed since the zero point of the yaw rate sensor was calibrated; The yaw rate calibration device according to any one of claims 1 to 10.

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