JP2019190850A - Device and method for correction of acceleration sensor - Google Patents

Abstract

To provide a device for correcting acceleration in two axial directions detected by a biaxial acceleration sensor to acceleration in a vehicle traveling direction and a vertical direction.SOLUTION: A device 10 includes a processing section 11. The processing section corrects the influence of the pitch angle from the Xs axis and the Zs axis acceleration based on the Xs axis acceleration value output by an acceleration sensor 1 in a reference state in which the vehicle is stationary on a plane perpendicular to the vertical direction, thereby obtaining the first correction Xs axis and the Zs axis acceleration. The processing section calculates the second correction Zs axis acceleration by correcting the influence of the roll angle from the first correction Zs axis acceleration based on the value of the Zs axis acceleration output from the acceleration sensor 1 in the reference state. The processing section corrects the influence of the yaw angle from the first correction Xs axis acceleration based on the reference acceleration in the Xc axis direction which is output from the acceleration sensor 2 and corrected, thereby obtaining the second correction Xs axis acceleration.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an apparatus and method for correcting an acceleration sensor.

  In recent years, an auto leveling mechanism that automatically adjusts the direction of the optical axis of a headlight of a vehicle according to the attitude of the vehicle is mounted on the vehicle.

  As shown in FIG. 1A, normally, the direction of the optical axis of the headlamp of the vehicle 100 is adjusted downward so that the driver's seat of the vehicle 101 facing the headlamp is not irradiated in the low beam state. ing.

  As shown in FIG. 1B, when a load is loaded on the rear trunk of the vehicle 100, the optical axis of the headlamp of the vehicle 100 faces upward due to a change in the posture of the vehicle, and the vehicle facing the headlamp. The driver's seat 101 may be illuminated.

  Therefore, as shown in FIG. 1C, a change in the posture of the vehicle when a load is loaded on the rear trunk of the vehicle 100 is detected and automatically adjusted so that the optical axis of the headlamp is directed downward. An automatic leveling mechanism has been proposed. By adjusting the optical axis of the headlamp of the vehicle 100 so as to face downward, the headlamp is prevented from illuminating the driver's seat of the vehicle 101 facing the headlamp.

  In the auto-leveling mechanism, for example, a vehicle height sensor is arranged on the suspension of the vehicle, and the posture of the vehicle is detected based on the detected change in the vehicle height.

  Patent Document 1 proposes an auto-leveling mechanism that automatically adjusts the direction of the optical axis of the headlamp by detecting a change in the attitude of the vehicle using an acceleration sensor that detects acceleration in three axis directions. Yes.

  The change in the posture of the vehicle can be detected based on the acceleration in the biaxial direction of the vehicle traveling direction and the vertical direction of the vehicle, but between the biaxial direction detected by the acceleration sensor and the vehicle traveling direction and the vertical direction of the vehicle. Deviation usually occurs. This is because when the acceleration sensor is mounted on the vehicle, a deviation occurs between the vehicle traveling direction and the vertical direction of the vehicle and the axial direction of the acceleration detected by the acceleration sensor. In Patent Document 1, an acceleration sensor that detects acceleration in three axial directions is used to correct this deviation.

JP 2014-108639 A

  In Patent Document 1, a process for correcting a deviation between the vehicle traveling direction and the vertical direction of the vehicle and the biaxial direction of the acceleration detected by the acceleration sensor is performed at a predetermined angle with respect to a plane orthogonal to the vertical direction. It is performed in a state where it is placed stationary on the surface that has been rotated.

  However, it is difficult to accurately set the state inclined by the predetermined angle described above. If the accuracy of the set inclination angle is not good, there is a possibility that the deviation between the vehicle traveling direction and the vertical direction of the vehicle and the biaxial direction of the acceleration detected by the acceleration sensor cannot be corrected correctly.

  In addition, when detecting a change in the posture of a vehicle using an acceleration sensor that detects acceleration in three axes, from the viewpoint of accurately detecting the acceleration in the vertical direction of the vehicle, for example, acceleration with a small detection range and high accuracy. A sensor is used.

  However, the acceleration sensor that detects the acceleration in the triaxial direction with a small detection range and high accuracy has a problem that the price is high.

  On the other hand, an acceleration sensor that detects biaxial acceleration is cheaper than an acceleration sensor that detects triaxial acceleration, even if the detection range is small and the accuracy is high.

  Therefore, an object of the present specification is to provide an apparatus and a method for correcting the biaxial acceleration detected by the biaxial acceleration sensor into the vehicle traveling direction and the vertical direction acceleration of the vehicle.

  According to the device disclosed in the present specification, the device corrects the output value of the first acceleration sensor mounted on the vehicle using a second acceleration sensor different from the first acceleration sensor mounted on the vehicle. The first acceleration sensor has a first axis facing the traveling direction of the vehicle and a second axis orthogonal to the first axis and facing the vertical direction, and outputs the first axial acceleration and the second axial acceleration. From the first axial acceleration and the second axial acceleration, the first acceleration sensor rotates around the third axis that faces the vehicle width direction orthogonal to the first and second axes, It has a processing unit that corrects the influence of the roll angle that rotates about one axis and the yaw angle that rotates about the second axis, and the processing unit is orthogonal to the vertical direction of the vehicle. The pitch output by the first acceleration sensor in the reference state placed stationary on the surface The first corrected first axial acceleration and the first corrected second axial direction in which the influence of the pitch angle is corrected from the first axial acceleration and the second axial acceleration based on the value of the first axial acceleration including the information of The acceleration is obtained, and in the reference state, the effect of the roll angle is further corrected from the first corrected second axial acceleration based on the value of the second axial acceleration including the roll angle information output by the first acceleration sensor. (2) Obtain the corrected second axis direction acceleration, and correct the influence of the yaw angle from the first corrected first axis direction acceleration based on the reference acceleration that is output from the second acceleration sensor and corrected to the acceleration directed in the first axis direction. Then, the second corrected first axial acceleration is obtained.

  Further, according to the method disclosed in the present specification, the first axis facing the traveling direction of the vehicle and the second axis orthogonal to the first axis and facing the vertical direction, and the first axial acceleration and the first axis A method for outputting biaxial acceleration and correcting an output value of a first acceleration sensor mounted on a vehicle by using a second acceleration sensor different from the first acceleration sensor mounted on the vehicle. Is a pitch in which the first acceleration sensor rotates about an axis facing the vehicle width direction orthogonal to the first axis and the second axis in a reference state in which is fixedly placed on a plane orthogonal to the vertical direction First corrected first axial direction in which the influence of the pitch angle is corrected from the first axial acceleration and the second axial acceleration based on the value of the first axial acceleration output by the first acceleration sensor including angular information. Obtaining acceleration and first corrected second axis acceleration, and reference state The first corrected second axial acceleration is based on the second axial acceleration value output by the first acceleration sensor including information on the roll angle at which the first acceleration sensor rotates about the first axis. The second correction second axis direction acceleration obtained by further correcting the influence of the roll angle from the first correction, and the first correction based on the reference acceleration that is output from the second acceleration sensor and corrected to the acceleration directed in the first axis direction And further correcting the influence of the yaw angle that the first acceleration sensor rotates about the second axis from the first axis direction acceleration to obtain the second corrected first axis direction acceleration.

  According to the apparatus disclosed in the present specification described above, the acceleration in the biaxial direction detected by the biaxial acceleration sensor can be corrected to the acceleration in the vehicle traveling direction and the vertical direction of the vehicle.

  Further, according to the method disclosed in the present specification, the biaxial acceleration detected by the biaxial acceleration sensor can be corrected to the vehicle traveling direction and vertical acceleration of the vehicle.

(A)-(C) is a figure explaining the automatic leveling which adjusts direction of the optical axis of the headlamp of a vehicle. It is a figure which shows the structure of one Embodiment of the system which correct | amends the acceleration sensor disclosed in this specification. It is a figure which shows the structure of an optical axis control apparatus. It is a figure which shows the coordinate system of a vehicle coordinate system and an acceleration sensor. (A) is a figure which shows the state in which a sensor coordinate system corresponds with a vehicle coordinate system, (B) is the state which the sensor coordinate system is rotating with respect to the vehicle coordinate system centering on the Xc axis | shaft. FIG. (C) is a view showing a state in which the sensor coordinate system is rotating with respect to the vehicle coordinate system about the Yc axis, and (D) is a vehicle coordinate system about the Zc axis. It is a figure which shows the state currently rotated with respect to. It is a flowchart (the 1) explaining operation | movement of the system which correct | amends an acceleration sensor. It is a flowchart (the 2) explaining operation | movement of the system which correct | amends an acceleration sensor. It is FIG. (1) explaining operation | movement of the system which correct | amends an acceleration sensor. It is FIG. (2) explaining operation | movement of the system which correct | amends an acceleration sensor. It is FIG. (3) explaining operation | movement of the system which correct | amends an acceleration sensor. It is FIG. (4) explaining operation | movement of the system which correct | amends an acceleration sensor. It is a flowchart explaining operation | movement of an optical axis control apparatus.

  Hereinafter, a preferred embodiment of a system for correcting an acceleration sensor disclosed in the present specification will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  FIG. 2 is a diagram illustrating a configuration of an embodiment of a system for correcting an acceleration sensor disclosed in the present specification. FIG. 3 is a diagram illustrating a configuration of the optical axis control device.

  As shown in FIG. 2, the system 1 of this embodiment includes an optical axis control device 10 and a skid prevention device 30 and is mounted on a vehicle 40.

  The optical axis control device 10 and the skid prevention device 30 are communicably connected via a network N such as CAN.

  The vehicle 40 includes a headlamp unit 20 whose optical axis is controlled by the optical axis control device 10. The headlamp unit 20 includes a headlamp 21 and a headlamp drive unit 22 that drives the headlamp 21 to adjust the direction of the optical axis.

  The skid prevention device 30 includes an acceleration sensor 31 that outputs acceleration of the vehicle 40 in the vehicle traveling direction and the vehicle width direction. The skid prevention device 30 determines the traveling direction of the vehicle based on the rotation difference of each wheel (not shown) of the vehicle 40 and the biaxial acceleration output from the acceleration sensor 31. Further, the skid prevention device 30 determines that the vehicle 40 is skidding when the determined traveling direction of the vehicle does not coincide with the traveling direction of the vehicle determined based on the operation position of the steering (not shown). The vehicle 40 is controlled so as to prevent skidding by determining the output of the engine (not shown) and controlling the braking unit (not shown).

  As illustrated in FIG. 3, the optical axis control device 10 includes a processing unit 11, a storage unit 12, an acceleration sensor 13, and a communication unit 14.

  In the system 1, the acceleration in the vehicle traveling direction and the vertical direction detected by the acceleration sensor 13 of the optical axis control device 10 are determined based on the acceleration in the vehicle traveling direction detected by the acceleration sensor 31 of the skid prevention device 30. A relationship for correcting the acceleration in the vehicle traveling direction and the vertical direction is obtained.

  Then, the optical axis control device 10 corrects the biaxial acceleration output from the acceleration sensor 13 based on the above-described relationship, and obtains the vehicle traveling direction and vertical acceleration of the traveling vehicle 40 to obtain the acceleration. Based on the measured acceleration, the pitch angle rotating around the axis of the vehicle 40 in the vehicle width direction is obtained. The optical axis control device 10 generates control information for controlling the direction of the optical axis of the headlamp 21 based on the obtained pitch angle, and transmits the control information to the headlamp drive unit 22.

  The headlamp driving unit 22 drives the headlamp 21 based on the control information received from the optical axis control device 10 to adjust the direction of the optical axis.

  Next, the optical axis control device 10 will be further described below.

  The processing unit 11 includes one or a plurality of processors and peripheral circuits. The processing unit 11 performs control and various processing of each hardware component of the optical axis control device 10 according to a computer program stored in advance in the storage unit 12, and temporarily stores data generated during the processing. The storage unit 12 is used. Note that the functions of the processing unit 11 may be implemented in the optical axis control device 10 as a circuit.

  The storage unit 12 may include a semiconductor memory such as a random access memory (RAM) or a read only memory (ROM), a magnetic disk, or a flash memory. The storage unit 12 may have a drive that can read a storage medium that stores a predetermined computer program in a non-temporary manner.

  The acceleration sensor 13 detects acceleration in two axial directions orthogonal to each other. When the optical axis control device 10 is disposed on the vehicle 40, the acceleration sensor 13 is preferably disposed on the vehicle 40 such that the first axis direction is in the vehicle traveling direction and the second axis direction is in the vertical direction. . As the acceleration sensor 13, for example, a MEMS sensor can be used.

  The communication unit 14 transmits / receives information to / from the skid prevention device 30 via the network N. The communication unit 14 transmits and receives information to and from the headlamp unit 20. The communication unit 14 may have a communication circuit and a communication line that perform wired transmission / reception.

  Next, a vehicle coordinate system fixed to the vehicle 40 and a sensor coordinate system fixed to the acceleration sensor 13 will be described below with reference to FIG.

  The vehicle coordinate system fixed to the vehicle 40 includes an Xc axis that faces the vehicle traveling direction in which the vehicle goes straight, a Zc axis that faces the vertical direction of the gravity direction, and a Yc axis that faces the vehicle width direction orthogonal to the Xc axis and the Zc axis. And have. The vehicle coordinate system is a rectangular coordinate system in which the Xc axis, the Yc axis, and the Zc axis are orthogonal to each other.

  The sensor coordinate system fixed to the acceleration sensor 13 is a rectangular coordinate system having an Xs axis, a Ys axis, and a Zs axis that are orthogonal to each other. The acceleration sensor 13 detects and outputs accelerations in the biaxial directions of the Xs axis direction and the Zs axis direction. The acceleration sensor 13 is preferably arranged on the vehicle 40 so that the Xs axis coincides with the direction of the Xc axis of the vehicle coordinate system and the Zs axis coincides with the direction of the Zc axis of the vehicle coordinate system. When the axis control device 10 is fixed to the vehicle 40, there may be a difference between the directions of the Xs axis and the Zs axis of the acceleration sensor 13 and the directions of the Xc axis and the Zc axis of the vehicle coordinate system. The acceleration sensor 13 is disposed on the vehicle 40 such that the Xs axis faces the Xc axis direction of the vehicle coordinate system and the Zs axis faces the Zc axis direction of the vehicle coordinate system. However, the Xs axis is not necessarily the vehicle coordinate system. The Xc axis direction is coincident with the Zs axis and the Zc axis direction of the vehicle coordinate system is not necessarily coincident.

  Next, the difference between the sensor coordinate system fixed to the acceleration sensor 13 and the vehicle coordinate system fixed to the vehicle 40 will be described below with reference to FIGS. 5 and 6.

  FIG. 5A shows a reference state in which the vehicle 40 is placed stationary on a plane P1 orthogonal to the vertical direction, and the directions of the three axes of the sensor coordinate system fixed to the acceleration sensor 13 are as follows. This is a case where the directions of the three axes of the vehicle coordinate system fixed at 40 coincide with the directions of the two coordinate systems.

  The acceleration value Gx0s in the Xs-axis direction detected by the acceleration sensor 13 is zero, and the acceleration value Gz0s in the Zs-axis direction is 1 (G).

  FIG. 5B shows a state in which the vehicle 40 is in the reference state, and the sensor coordinate system fixed to the acceleration sensor 13 matches the Xs axis with the Xc axis of the vehicle coordinate system fixed to the vehicle 40. It is rotated by a predetermined angle around the axis. This predetermined angle is called a roll angle.

  The acceleration value Gx0s in the Xs-axis direction detected by the acceleration sensor 13 is zero, and the acceleration value Gz0s in the Zs-axis direction is a value smaller than 1 (G) because a component in the Ys direction is generated.

  FIG. 6C shows that the vehicle coordinate system fixed to the acceleration sensor 13 is in the reference state, and the Ys axis matches the Yc axis of the vehicle coordinate system fixed to the vehicle 40. It is rotated by a predetermined angle around the axis. This predetermined angle is called a pitch angle.

  The acceleration value Gx0s in the Xs axis direction detected by the acceleration sensor 13 is a positive or negative value ax corresponding to the rotation angle, and the acceleration value Gz0s in the Zs axis direction is 1 (G) because a component in the Xs direction is generated. ) Is a smaller value.

  FIG. 6D shows a state in which the vehicle 40 is in the reference state, and the sensor coordinate system fixed to the acceleration sensor 13 matches the Zs axis with the Zc axis of the vehicle coordinate system fixed to the vehicle 40. It is rotated by a predetermined angle around the axis. This predetermined angle is called a yaw angle.

  The acceleration value Gx0s in the Xs-axis direction detected by the acceleration sensor 13 is zero, and the acceleration value Gz0s in the Zs-axis direction is 1 (G).

  The direction of the three axes of the sensor coordinate system of the acceleration sensor 13 included in the optical axis control device 10 is one with respect to the direction of the three axes of the vehicle coordinate system according to the posture of the optical axis control device 10 fixed to the vehicle. It can be in a state of not doing it.

  When the orientation of the three axes of the sensor coordinate system of the acceleration sensor 13 does not coincide with the orientation of the three axes of the vehicle coordinate system, one or more of a roll angle, a pitch angle, and a yaw angle are generated.

  When the acceleration value Gx0s detected by the acceleration sensor 13 in the Xs-axis direction is zero, the pitch angle is zero. In other words, when the acceleration value Gx0s detected by the acceleration sensor 13 in the Xs-axis direction is not zero, a non-zero pitch angle (state in FIG. 6A) is generated. Therefore, based on the acceleration value Gx0s detected by the acceleration sensor 13 in the Xs-axis direction, it is possible to identify the occurrence of a non-zero pitch angle.

  When the acceleration value Gz0s detected by the acceleration sensor 13 is smaller than 1 (G), the roll angle is not zero (the state in FIG. 5B) and / or the pitch angle (FIG. 6). (State (A)) has occurred.

  However, when the direction of the three axes of the sensor coordinate system of the acceleration sensor 13 is coincident with the direction of the three axes of the vehicle coordinate system (the state shown in FIG. 5A), and when the yaw angle is generated. (The state in FIG. 6B) is the same as the Xs-axis direction acceleration value detected by the acceleration sensor 13 and the Zs-axis direction acceleration value. The occurrence of a non-zero yaw angle cannot be identified based on the acceleration value in the Zs-axis direction.

  As will be described below, the system 1 determines the Xs-axis direction detected by the acceleration sensor 13 based on the deviation between the three-axis direction of the sensor coordinate system of the acceleration sensor 13 and the three-axis direction of the vehicle coordinate system. A relationship for correcting the acceleration and the acceleration in the Zs-axis direction to the vehicle traveling direction and vertical acceleration of the vehicle 40 is obtained. Based on this relationship, the optical axis control device 10 can obtain the acceleration in the vehicle traveling direction and the acceleration in the vertical direction of the vehicle based on the acceleration in the Xs axis direction and the acceleration in the Zs axis direction detected by the acceleration sensor 13. become. Then, the optical axis control device 10 generates control information for controlling the direction of the optical axis of the headlamp 21 based on the acceleration in the vehicle traveling direction and the acceleration in the vertical direction of the vehicle. Adjust the direction of the axis.

  The sensor coordinate system fixed to the acceleration sensor 31 of the skid prevention device 30 may also be displaced from the vehicle coordinate system, similar to the sensor coordinate system fixed to the acceleration sensor 13 described above.

  In the skid prevention device 30, the acceleration sensor 31 rotates about the Yc axis and the acceleration sensor 31 about the Xc axis with respect to the acceleration in the vehicle traveling direction and the vehicle width direction detected by the acceleration sensor 31. A correction relationship for correcting the influence of the rotating roll angle and the yaw angle at which the acceleration sensor 31 is rotating around the Zc axis has already been obtained. As a method for correcting the acceleration detected by the acceleration sensor 31, a known technique can be used. Normally, it is not necessary to correct the influence of the roll angle at which the acceleration sensor 31 rotates about the Xc axis with respect to the acceleration in the vehicle traveling direction detected by the acceleration sensor 31.

  The skid prevention device 30 corrects the biaxial acceleration detected by the acceleration sensor 31 in the vehicle traveling direction and the vehicle width direction of the vehicle coordinate system, and then performs processing to prevent skidding.

  Further, the skid prevention device 30 transmits an acceleration obtained by correcting the acceleration in the vehicle traveling direction detected by the acceleration sensor 31 (hereinafter also referred to as a reference acceleration Gxe) to the optical axis control device 10 via the network N.

  The optical axis control device 10 determines the vehicle travel of the vehicle 40 based on the acceleration in the vehicle travel direction corrected by the acceleration sensor 31 of the skid prevention device 30 with respect to the biaxial acceleration detected by the acceleration sensor 31. The relationship for correcting the acceleration in the direction and the vertical direction is obtained.

  Hereinafter, the operation of the system 1 described above will be described with reference to the flowcharts shown in FIGS. 7 and 8.

  First, in step S701, the vehicle 40 in which the optical axis control device 10 is fixedly placed is in a reference state in which it is placed stationary on a plane P1 perpendicular to the vertical direction. The allowable range of deviation from the angle at which the plane P1 is orthogonal to the vertical direction is appropriately determined based on the accuracy of acceleration necessary for the optical axis control device 10 to generate control information for controlling the optical axis. Can be done. First, the process of step S701 will be described below with reference to FIG.

  FIG. 9 shows the Xs axis and Zs axis of the sensor coordinate system fixed to the acceleration sensor 13 and the Xc axis and Zc axis of the vehicle coordinate system with the origins O and the Ys axis and Yc axis aligned. .

  The sensor coordinate system rotates about the Yc axis by a pitch angle α with the direction of the Ys axis coinciding with the Yc axis of the vehicle coordinate system. Here, 0 = <α = <π.

  The acceleration value in the Xs axis direction detected by the acceleration sensor 13 in the reference state is Gx0s, and the acceleration value in the Zs axis direction is Gz0s.

  As shown in FIG. 9, since the acceleration value Gx0s in the Xs-axis direction is a projection component of the gravitational acceleration 1 (G) in the Xs-axis direction, it is expressed by Expression (1).

  That is, the sine of the pitch angle α is represented by an acceleration value Gx0s in the Xs axis direction. The acceleration represented by Expression (1) is a value that is always measured by the acceleration sensor 13 while the vehicle 40 is stationary and running.

  In step S701, the processing unit 11 of the optical axis control device 10 determines whether or not the absolute value of the Xs-axis direction acceleration value Gx0s detected by the acceleration sensor 13 is smaller than a predetermined threshold Th1. Here, when the absolute value of the acceleration value Gx0s is smaller than the predetermined threshold Th1, the pitch angle α is considered to be zero. The predetermined threshold Th1 can be set to 0.05 G, for example, although it depends on the accuracy of the acceleration sensor 13.

  When the absolute value of the acceleration value Gx0s is smaller than the predetermined threshold Th1 (step S701—Yes), the processing unit 11 determines that the pitch angle α = 0. Then, the processing unit 11 determines that sin α = 0 and cos α = 1 (step S703).

  On the other hand, when the absolute value of the acceleration value Gx0s is not smaller than the predetermined threshold Th1 (step S701-No), a non-zero pitch angle α is generated. The processing (step S705) of the processing unit 11 in this case will be described below with reference to FIG.

  As described above with reference to FIG. 9, the acceleration value Gx0s in the Xs-axis direction is a projection component of the gravitational acceleration 1 (G) in the Xs-axis direction, and is expressed by Expression (1).

  That is, since the sine of the pitch angle α is represented by the acceleration value Gx0s in the Xs-axis direction, the processing unit 11 determines sin α = Gx0s.

  Further, the relationship between the cosine of the pitch angle α and the acceleration value Gx0s in the Xs-axis direction is expressed by equation (2) using sin α or Gx0s. The processing unit 11 obtains cos α using Expression (2).

  The above is the description of step S705.

  Next, the process of step S707 will be described below with reference to FIG.

  The acceleration Gx1 in which the pitch angle α is corrected with respect to the acceleration Gx0 in the Xs axis direction detected by the acceleration sensor 13 is expressed by Expression (3) using sin α and cos α or Gx0s.

  The acceleration Gx1 with the corrected pitch angle α is obtained by subtracting the acceleration value Gx0s detected even when the vehicle 40 is stationary from the Xs-axis direction acceleration Gx0 detected by the acceleration sensor 13, as shown in FIG. It is obtained as a component projected in the Xc-axis direction of the vehicle coordinate system.

  When the pitch angle α is zero, sin α = 0 and cos α = 1, and the relationship of Gx1 = Gx0 is obtained from the equation (3), so the equation (3) also includes the relationship shown in step S703.

  As shown in FIG. 9, the acceleration value Gz0s detected in the reference state by the acceleration sensor 13 in the Zs-axis direction is a projection component of the gravitational acceleration 1 (G) in the Zs-axis direction. expressed.

  Similarly, with respect to the acceleration Gz0 detected by the acceleration sensor 13 in the Zs-axis direction, the relationship between the acceleration Gz1 whose pitch angle α is corrected and the acceleration Gz0 detected by the acceleration sensor 13 in the Zs-axis direction is It is represented by Formula (5).

  When equation (5) is solved for acceleration Gz1, acceleration Gz1 is expressed by equation (6) using cos α or Gx0s.

  When the pitch angle α is zero, cos α = 1, and the relationship of Gz1 = Gz0 is obtained from the equation (6). Therefore, the equation (6) also includes the relationship shown in step S703.

  In step S707, the processing unit 11 obtains an expression (3) representing the acceleration Gx1 in which the pitch angle α is corrected with respect to the acceleration Gx0 in the Xs axis direction detected by the acceleration sensor 13. Specifically, the processing unit 11 obtains Expression (3) by substituting the value of the acceleration in the Xs axis direction detected by the acceleration sensor 13 in the reference state as Gx0s in Expression (3). Further, the processing unit 11 obtains Expression (6) representing the acceleration Gz1 in which the pitch angle α is corrected with respect to the acceleration Gz0 in the Zs-axis direction detected by the acceleration sensor 13. Specifically, the processing unit 11 obtains Expression (6) by substituting the value of acceleration in the Zs-axis direction detected by the acceleration sensor 13 in the reference state as Gz0s in Expression (6).

  Thereby, the pitch angle α is corrected with respect to the acceleration in the Xs axis direction and the acceleration in the Zs axis direction detected by the acceleration sensor. The accelerations Gx1 and Gz1 in which the pitch angle α is corrected mean accelerations detected when the acceleration sensor 13 is attached to the vehicle 40 with the pitch angle α being zero.

  The above is the description of step S707.

  Next, the process of step S709 will be described below with reference to FIG.

  FIG. 10 shows the Ys axis and Zs axis of the sensor coordinate system fixed to the acceleration sensor 13 and the Yc axis and Zc axis of the vehicle coordinate system with the origins O and the Xs axis and Xc axis being matched. .

  The sensor coordinate system is rotated by a roll angle β around the Xc axis with the Xs axis direction aligned with the Xc axis of the vehicle coordinate system. Here, 0 = <β = <π.

  Here, the acceleration value in which the pitch angle α in the Zs-axis direction detected by the acceleration sensor 13 in the reference state is corrected is defined as Gz1s. The processing unit 11 substitutes the acceleration value Gz1s for the Xs-axis direction detected by the acceleration sensor 13 and the acceleration value Gz0s for the Zs-axis direction detected by the acceleration sensor 13 in the reference state into the equation (6). You may ask for it.

  As shown in FIG. 10, since the acceleration value Gz1s corrected for the pitch angle α in the Zs-axis direction is a projection component of the gravitational acceleration 1 (G) in the Zs-axis direction, the roll angle β is used to obtain equation (7). It is represented by

  In step S709, the processing unit 11 determines whether or not the absolute value of the difference between the acceleration value Gz1s with the corrected pitch angle α and 1 is smaller than a predetermined threshold Th2. Here, when the absolute value of the difference between the acceleration values Gz1s and 1 is smaller than the predetermined threshold Th2, the roll angle is considered to be zero. The predetermined threshold Th2 can be set to 0.05 G, for example, although it depends on the accuracy of the acceleration sensor 13.

  When the absolute value of the difference between the acceleration value Gz1s and 1 with the corrected pitch angle α is smaller than the predetermined threshold Th2 (step S711—Yes), the processing unit 11 determines that the roll angle β = 0. Then, the processing unit 11 determines that cos β = 1 (step S711).

  On the other hand, if the absolute value of the difference between the acceleration value Gz1s and 1 with the corrected pitch angle α is not smaller than the predetermined threshold Th2 (No in step S711), a non-zero roll angle β is generated. It will be. The processing (step S713) of the processing unit 11 in this case will be described below with reference to FIG.

  As described with reference to FIG. 10, the acceleration value Gz1s in which the pitch angle α in the Zs-axis direction is corrected is a projection component of the gravitational acceleration 1 (G) in the Zs-axis direction. Is done.

  The relationship between the right side in equation (7) and the acceleration value Gz1s is derived using the relationship in equation (6). The processing unit 11 obtains the value of cos β based on the acceleration value Gz0s in the Zs axis direction detected by the acceleration sensor 13 in the reference state and cos α.

  The above is the description of step S713.

  Next, the process of step S715 will be described below with reference to FIG.

  In the same manner as the expression (7) is derived, the acceleration Gz1 with the corrected pitch angle α detected by the acceleration sensor 13 and the acceleration Gz2 with the corrected roll angle β are detected by the acceleration sensor 13. The relationship with the acceleration Gz1 in which the pitch angle α is corrected is expressed by Expression (8).

  When equation (8) is solved for acceleration Gz2, equation (9) is obtained.

  When the roll angle β is zero, cos β = 1, and the relationship of Gz2 = Gz1 is obtained from the equation (9), so the equation (9) also includes the relationship shown in step S711.

  In step S715, the processing unit 11 obtains an expression (9) representing the acceleration Gz2 with the roll angle β corrected with respect to the acceleration Gz1 with the pitch angle α detected by the acceleration sensor 13 corrected. Specifically, the processing unit 11 substitutes the acceleration value in the Xs axis direction and the acceleration value in the Zs axis direction detected by the acceleration sensor 13 in the reference state as Gx0s and Gz0s in the equation (9). Equation (9) is obtained.

  Further, the acceleration Gz2 in which the pitch angle α and the roll angle β are corrected is the acceleration Gzsen detected by the acceleration sensor 13 in the Zs-axis direction and the acceleration value Gz0s detected in the reference state by the acceleration sensor 13 in the Zs-axis direction. And can be expressed as shown in Equation (10). The acceleration Gz2 in which the pitch angle α and the roll angle β are corrected means an acceleration detected when the acceleration sensor 13 is attached to the vehicle 40 with the pitch angle α and the roll angle β being zero.

  The processing unit 11 uses the relationship shown in Expression (10) to calculate the acceleration Gzsens in the Zs-axis direction of the sensor coordinate system detected by the acceleration sensor 13 of the traveling vehicle 40 as the acceleration in the Zc-axis direction of the vehicle coordinate system. Correct to match.

  Next, processing in steps S801 to S813 will be described below.

  In the processing of steps S801 to S813, correction for correcting the acceleration Gx1 so that the acceleration Gx1 represented by the equation (6) matches the reference acceleration Gxe based on the reference acceleration Gxe received from the skid prevention device 30. By determining the coefficient, the influence of the yaw angle is corrected. Since the processes of steps S801 to S813 are performed when the road surface on which the vehicle is located is inclined at a predetermined inclination angle with respect to the plane orthogonal to the vertical direction, the process is normally executed while the vehicle 40 is traveling. Since the road surface on which the vehicle is located has only to be inclined at a predetermined inclination angle with respect to the plane orthogonal to the vertical direction, the vehicle 40 may be stopped.

  First, in step S801, the processing unit 11 sets 1 as an initial value as the correction coefficient Cx. The product of the correction coefficient Cx and the acceleration Gx1 expressed by the equation (6) corrects the yaw angle with respect to the acceleration in the vehicle traveling direction detected by the acceleration sensor 13, and the vehicle traveling direction in the vehicle coordinate system is corrected. Acceleration is required.

  Next, in step S803, the processing unit 11 determines whether or not the first correction coefficient has already been obtained. The processing unit 11 determines whether or not the first correction coefficient has already been obtained based on the flag. The first correction coefficient and the flag will be described later.

  If the first correction coefficient has already been obtained (step S803—Yes), the process proceeds to step S809. On the other hand, when the first correction coefficient has not been obtained (step S803—No), the process proceeds to step S805.

  Next, in step S805, the processing unit 11 determines whether or not the road surface on which the vehicle 40 is located is inclined at a first inclination angle with respect to a plane orthogonal to the vertical direction. In the system 1, the processing unit 11 determines whether or not the vehicle 40 is inclined at the first inclination angle with respect to the road surface based on the acceleration Gx1 represented by the equation (6) and the reference acceleration Gxe. .

  The process of step S805 will be described below with reference to FIG.

  In FIG. 11, the vehicle 40 is placed in a stationary state on a plane P <b> 2 obtained by rotating the plane P <b> 1 by a predetermined angle θ around an axis that faces the Yc axis direction of the vehicle coordinate system. This corresponds to a state in which the vehicle 40 is traveling on a road surface that is inclined with respect to a plane orthogonal to the vertical direction.

  FIG. 11 shows the Xc axis and the Zc axis of the vehicle coordinate system of the vehicle 40 together with the vertical direction.

  As shown in FIG. 11, the component obtained by projecting the gravitational acceleration 1 (G) in the vertical direction in the Xc-axis direction of the vehicle coordinate system is the reference acceleration Gxe transmitted by the skid prevention device 30, and is expressed by the equation (11). expressed.

  When the road surface on which the vehicle 40 is located is not inclined with respect to the plane orthogonal to the vertical direction, the inclination angle θ is zero, so the reference acceleration Gxe is zero. When the reference acceleration Gxe is zero, the value of the acceleration Gx1 expressed by the equation (6) is also small. Therefore, even if the influence of the yaw angle is not corrected, the acceleration Gx1 has a small difference from the reference acceleration Gxe. Conceivable.

  On the other hand, when the road surface on which the vehicle 40 is located is inclined with respect to a plane orthogonal to the vertical direction, the reference acceleration Gxe increases according to the inclination angle θ. As the tilt angle θ increases, the difference between the acceleration Gx1 that is not corrected for the influence of the yaw angle and the reference acceleration Gxe is considered to increase.

  It is preferable to obtain the correction coefficient Cx when the difference between the acceleration Gz1 and the reference acceleration Gxe is large from the viewpoint of improving the accuracy of the correction coefficient Cx. Therefore, in step S805, the processing unit 11 determines whether or not the road surface on which the vehicle 40 is located is inclined at the first inclination angle with respect to the plane orthogonal to the vertical direction.

  Specifically, the processing unit 11 has a case where the absolute value of the reference acceleration Gxe is within the first predetermined range and the absolute value of the difference between the acceleration Gx1 and the reference acceleration Gxe is less than or equal to a predetermined threshold Th3. The vehicle 40 is determined to be inclined at the first inclination angle with respect to the road surface. The first predetermined range is an angle corresponding to the first inclination angle. The first predetermined range can be determined, for example, based on the value of the reference acceleration Gxe detected while the vehicle 40 is traveling on a road surface inclined at the first inclination angle. The first tilt angle can be set to, for example, 5 degrees to 10 degrees. The predetermined threshold Th3 can be set to 0.05 G, for example, although it depends on the accuracy of the acceleration sensor 13. That is, the processing unit 11 determines whether or not the vehicle 40 is located on a road surface that is inclined at an angle within a predetermined range with the first inclination angle as a reference. Here, it may be determined based on a difference between the reference acceleration Gxe and the acceleration before correcting the influence of the pitch angle output from the acceleration sensor 13. Since the reference acceleration Gxe is also corrected for the influence of the pitch angle, it is not preferable to use the difference from the acceleration output by the acceleration sensor 13 before correcting the influence of the pitch angle because the influence of the pitch angle is included.

  When the road surface on which the vehicle 40 is located is not inclined at the first inclination angle with respect to the plane orthogonal to the vertical direction (step S805—No), the process proceeds to step S809. On the other hand, the process (step S807) in the case where the road surface on which the vehicle 40 is located is inclined at the first inclination angle with respect to the plane orthogonal to the vertical direction (step S805-Yes) is described with reference to FIG. This will be described below.

  FIG. 12 shows the Xs axis and Ys axis of the sensor coordinate system fixed to the acceleration sensor 13 and the Xc axis and Yc axis of the vehicle coordinate system, with the origins O and the Zs axis and Zc axis aligned. .

  The sensor coordinate system is rotated by the yaw angle δ around the Zc axis with the direction of the Zs axis made coincident with the Zc axis of the vehicle coordinate system. Here, 0 = <δ = <π.

  The acceleration Gx1 expressed by the equation (6) detected by the acceleration sensor 13 and the pitch angle is corrected corresponds to the magnitude of the acceleration in the Xs-axis direction of the sensor coordinate system. The reference acceleration Gxe corresponds to the magnitude of acceleration in the Xc axis direction of the vehicle coordinate system.

  A component obtained by projecting the acceleration Gx1 in the Xc-axis direction of the vehicle coordinate system is a reference acceleration Gxe. Therefore, the reference acceleration Gxe is expressed by Expression (12) using the acceleration Gx1 and the cosine of the yaw angle δ.

  The processing unit 11 obtains a first correction coefficient Cx1 that is a quotient obtained by dividing the reference acceleration Gxe by the acceleration Gx1, using Expression (13).

  For example, the processing unit 11 may obtain the first correction coefficient Cx1 as an average value of 50 to 100 quotients obtained by dividing the reference acceleration Gxe by the acceleration Gx1.

  Then, the processing unit 11 changes the flag indicating that the first correction coefficient Cx1 has been obtained from 0 to 1. In step S803 described above, the processing unit 11 determines whether or not the first correction coefficient Cx1 is obtained based on the flag value.

  The above is the description of step S807.

  Next, in step S809, the processing unit 11 determines whether or not the road surface on which the vehicle 40 is located is inclined at a second inclination angle larger than the first inclination angle with respect to a plane orthogonal to the vertical direction. . In the system 1, the processing unit 11 determines whether or not the vehicle 40 is inclined at the second inclination angle with respect to the road surface based on the acceleration Gx1 expressed by the equation (6) and the reference acceleration Gxe. .

  Specifically, when the absolute value of the reference acceleration Gxe is within the second predetermined range and the absolute value of the difference between the acceleration Gx1 and the reference acceleration Gxe is equal to or less than the predetermined threshold Th4, the processing unit 11 The vehicle 40 is determined to be inclined at the second inclination angle with respect to the road surface. The second predetermined range is an angle corresponding to the second inclination angle. The second predetermined range can be determined based on, for example, the value of the reference acceleration Gxe detected while the vehicle 40 is traveling on a road surface inclined at the second inclination angle. The second tilt angle can be set to, for example, 10 degrees to 90 degrees. The predetermined threshold Th4 can be set to 0.05 G, for example, although it depends on the accuracy of the acceleration sensor 13. That is, the processing unit 11 determines whether or not the vehicle 40 is located on a road surface that is inclined at an angle within a predetermined range with the second inclination angle as a reference.

  When the road surface on which the vehicle 40 is located is not inclined at the second inclination angle with respect to the plane orthogonal to the vertical direction (step S809—No), the process returns to step S803. On the other hand, when the road surface on which the vehicle 40 is located is inclined at the second inclination angle with respect to the plane orthogonal to the vertical direction (step S809—Yes), the processing unit 11 divides the reference acceleration Gxe by the acceleration Gx1. A second correction coefficient Cx2 that is a quotient is obtained from equation (14) (step S811).

  For example, the processing unit 11 may obtain the second correction coefficient Cx2 as an average value of 50 to 100 quotients obtained by dividing the reference acceleration Gxe by the acceleration Gx1.

  The above is the description of step S811.

  Next, in step S813, the processing unit 11 obtains a correction coefficient Cx that is an average value of the first correction coefficient Cx1 and the second correction coefficient Cx2 using Expression (15).

  Thus, a highly accurate correction coefficient can be obtained by obtaining the correction coefficient Cx as an average value of the first correction coefficient and the second correction coefficient obtained with different inclination angles of the road surface on which the vehicle 40 is located. it can.

  Further, since the correction coefficient Cx is obtained by performing the processes of steps S805 to S813 described above while the vehicle 40 is traveling, these processes need not be performed before traveling.

  Note that the processing unit 11 may obtain the correction coefficient Cx using one of the first correction coefficient and the second correction coefficient.

  The acceleration Gx2 in which the yaw angle δ is corrected with respect to the acceleration Gx1 can be expressed as shown in Expression (16) using the correction coefficient Cx.

  Similarly, the acceleration Gx2 in which the pitch angle α and the yaw angle δ are corrected with respect to the acceleration Gzsens in the Xs-axis direction detected by the acceleration sensor 13 is expressed by the equation (3) using the correction coefficient Cx and the equation (3). 17). The acceleration Gx2 means an acceleration detected when the acceleration sensor 13 is attached to the vehicle 40 with a pitch angle α and a yaw angle γ being zero.

  Next, the operation in which the optical axis control device 10 controls the optical axis of the headlamp 21 based on the acceleration Gxsen in the Xs axis direction and the acceleration Gzsen in the Zs axis direction detected by the acceleration sensor 13 is shown in FIG. This will be described below with reference to the flowchart shown.

  First, in step S1301, the processing unit 11 of the optical axis control device 10 calculates the acceleration Gx2 in the Xc-axis direction of the vehicle coordinate system based on the acceleration Gxsen in the Xs-axis direction detected by the acceleration sensor 13 (17). Find using.

  Further, the processing unit 11 obtains the acceleration Gz2 in the Zc-axis direction of the vehicle coordinate system based on the acceleration Gzsen in the Zs-axis direction detected by the acceleration sensor 13 using Expression (10).

  Here, when the correction coefficient Cx has not been obtained by the processes in steps S805 to S813 described above, an initial value of 1 is used as the correction coefficient Cx. In this case, the reference acceleration Gxe output from the skid prevention device 30 is used as the acceleration Gx2 in the Xc-axis direction of the vehicle coordinate system. In the optical axis control device 10, between the time when the acceleration sensor 13 detects the acceleration Gzsen in the Zs-axis direction and the time when the reference acceleration Gxe output from the skid prevention device 30 is detected by the acceleration sensor 31. Although a difference of about 10 msec may occur, it is considered that this difference hardly affects the control of the direction of the optical axis of the headlamp 21 during normal vehicle travel. .

  Next, in step S1303, the processing unit 11 rotates the vehicle 40 around an axis that faces the vehicle width direction based on the vehicle traveling direction and vertical accelerations Gx2 and Gz2 of the traveling vehicle 40. Find the pitch angle. And the optical axis control apparatus 10 produces | generates the control information which controls the direction of the optical axis of the headlamp 21 based on the calculated | required pitch angle.

  In step S <b> 1305, the processing unit 11 outputs control information for controlling the direction of the optical axis of the headlamp 21 to the headlamp unit 20 using the communication unit 14.

  Based on the control information received from the optical axis control device 10, the headlamp drive unit 22 of the headlamp unit 20 drives the headlamp 21 to adjust the direction of the optical axis.

  The processing of steps S1301 to S1305 described above is repeatedly executed when the ignition key of the vehicle 40 is turned on, and ends when the ignition key is turned off.

  According to the system of the present embodiment described above, the acceleration in the biaxial direction detected by the biaxial acceleration sensor can be accurately corrected to the acceleration in the vehicle traveling direction and the vertical direction of the vehicle. Thereby, the optical axis control device accurately obtains the acceleration in the vehicle traveling direction and the vertical direction of the vehicle based on the corrected acceleration in the vehicle traveling direction and the vertical direction of the vehicle. The direction of the optical axis of the lighting can be controlled. In addition, the cost can be reduced by using an acceleration sensor that detects acceleration in two axial directions. Furthermore, since the acceleration in the vehicle traveling direction and the vertical direction of the vehicle are obtained based on the values detected by the same acceleration sensor, the timing shift as when using the values detected by different acceleration sensors is also eliminated.

  In the present invention, the method and apparatus for correcting the acceleration sensor of the above-described embodiment can be changed as appropriate without departing from the spirit of the present invention.

  For example, in the above-described embodiment, in step S805 and step S809, the processing unit 11 indicates that the road surface is inclined at a predetermined inclination angle by the acceleration Gx1 expressed by the equation (6) and the reference acceleration Gxe. However, the determination may be made using other methods. For example, the processing unit 11 may detect that the road surface is inclined at a predetermined inclination angle based on the biaxial acceleration detected by the acceleration sensor 13. The processing unit 11 may detect that the road surface is inclined at a predetermined inclination angle using a gyro sensor mounted on the vehicle 40.

  In the above-described embodiment, the reference acceleration that is output by the acceleration sensor of the skid prevention device and corrected to the acceleration in the direction of the axis that faces the traveling direction is used, but the detection range is narrow and high-precision acceleration is used. As long as the acceleration sensor outputs, the output value of another acceleration sensor may be used as the reference acceleration. For example, a collision detection sensor or an acceleration sensor of a drive recorder may be used.

DESCRIPTION OF SYMBOLS 1 System 10 Optical axis control apparatus 11 Processing part 12 Storage part 13 Acceleration sensor 14 Communication part 20 Headlamp unit 21 Headlamp 22 Headlamp drive part 30 Side slip prevention apparatus 31 Acceleration sensor 40 Vehicle

Claims (8)

An apparatus for correcting an output value of a first acceleration sensor mounted on a vehicle using a second acceleration sensor different from the first acceleration sensor mounted on the vehicle,
The first acceleration sensor has a first axis that faces the traveling direction of the vehicle and a second axis that is orthogonal to the first axis and faces the vertical direction. The first acceleration sensor also measures the first axial acceleration and the second axial acceleration. Output,
From the first axis direction acceleration and the second axis direction acceleration, the pitch at which the first acceleration sensor rotates about a third axis that faces in the vehicle width direction orthogonal to the first axis and the second axis An angle, a roll angle rotating around the first axis, and a processing unit for correcting the influence of the yaw angle rotating around the second axis,
The processor is
Based on the value of the first axial acceleration including the pitch angle information output by the first acceleration sensor in a reference state in which the vehicle is stationary on a plane orthogonal to the vertical direction, Obtaining a first corrected first axial acceleration and a first corrected second axial acceleration in which the influence of the pitch angle is corrected from the first axial acceleration and the second axial acceleration,
In the reference state, the influence of the roll angle is further corrected from the first corrected second axial acceleration based on the second axial acceleration value including the roll angle information output by the first acceleration sensor. The second corrected second axis direction acceleration is obtained,
Based on the reference acceleration output from the second acceleration sensor and corrected to the acceleration directed in the first axis direction, the influence of the yaw angle is corrected from the first corrected first axis direction acceleration, and the second correction is performed. A device for obtaining the first axial acceleration. The processor is
When a road surface on which the vehicle is located is inclined with respect to a plane perpendicular to the vertical direction, a correction coefficient that is a quotient obtained by dividing the reference acceleration by the first correction first axis direction acceleration is obtained.
The apparatus according to claim 1, wherein the second corrected first axial acceleration is obtained by a product of the correction coefficient and the first corrected first axial acceleration. The processor is
A first correction coefficient that is a quotient obtained by dividing the reference acceleration by the first correction first axial acceleration when the road surface on which the vehicle is located is inclined at a first inclination angle with respect to a plane orthogonal to the vertical direction. Seeking
A second correction coefficient that is a quotient obtained by dividing the reference acceleration by the first correction first axial acceleration when the road surface on which the vehicle is located is inclined at a second inclination angle with respect to a plane orthogonal to the vertical direction. Seeking
The apparatus according to claim 2, wherein an average value of the first correction coefficient and the second correction coefficient is obtained as the correction coefficient.   The apparatus according to claim 2, wherein the processing unit determines that the vehicle is inclined with respect to a road surface based on the first corrected first axial acceleration and the reference acceleration. The processor is
In the reference state, the first axial acceleration Gx0 is corrected based on the first axial acceleration value Gx0s output by the first acceleration sensor, which is the product of gravity acceleration and the sine of the pitch angle. The first corrected first axial acceleration Gx1 is obtained by the following equation (1),

The first corrected second axial acceleration Gz1 obtained by correcting the second axial acceleration Gz0 is obtained by the following equation (2).

Apparatus according to any one of claims 1 to 4. The processor is
In the reference state, the first axis direction acceleration value Gx0s output by the first acceleration sensor and the second axis output by the first acceleration sensor, which is the product of gravity acceleration and the cosine of the roll angle. Based on the direction acceleration value Gz0s, the second corrected second axial acceleration Gz2 obtained by correcting the first corrected second axial acceleration Gz1 is obtained by the following equation (3).

The apparatus according to claim 5.   The device according to claim 1, wherein the second acceleration sensor is an acceleration sensor included in a skid prevention device. A first axis that faces the traveling direction of the vehicle and a second axis that is perpendicular to the first axis and faces the vertical direction, and outputs a first-axis acceleration and a second-axis acceleration, and is mounted on the vehicle. A method of correcting the output value of the first acceleration sensor using a second acceleration sensor different from the first acceleration sensor mounted on the vehicle,
In a reference state in which the vehicle is stationary on a plane orthogonal to the vertical direction, the first acceleration sensor is centered on an axis that faces the vehicle width direction orthogonal to the first axis and the second axis. Based on the value of the first axial acceleration output from the first acceleration sensor including information on the rotating pitch angle, the influence of the pitch angle is determined from the first axial acceleration and the second axial acceleration. Obtaining a corrected first corrected first axial acceleration and a first corrected second axial acceleration;
Based on a value of the second axial acceleration output by the first acceleration sensor including information on a roll angle at which the first acceleration sensor rotates about the first axis in the reference state, Obtaining a second corrected second axial acceleration obtained by further correcting the influence of the roll angle from the first corrected second axial acceleration;
The first acceleration sensor is centered on the second axis from the first corrected first axis direction acceleration based on the reference acceleration that is output by the second acceleration sensor and corrected to the acceleration directed in the first axis direction. Further correcting the influence of the rotating yaw angle to obtain the second corrected first axis direction acceleration,
Including methods.

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