JP2019035629A - Calibration device, calibration method, rotational angle detector, and program - Google Patents

Abstract

To reduce an error in a detection angle because of an error in a mounting position.SOLUTION: In a calibration device of a rotational angle detector for calculating a magnetic field in an X-axis direction and a magnetic field in a Y-axis direction in an XY plane, and detecting a rotational angle in the XY plane of a magnetic field generation source rotating around a rotation axis, the rotational angle detector includes an XY magnetic field detection part for detecting the magnetic field in an X-axis direction and the magnetic field in a Y-axis direction, and a Z magnetic field detection part including two pairs of sensor elements that are disposed while sandwiching the XY magnetic field detection part in the XY plane, and each detect a magnetic field in a Z-axis direction vertical to the XY plane. The calibration device includes: an acquisition part for acquiring an output signal corresponding to magnetic field detection results in the XY magnetic field detection part and the Z magnetic field detection part when the magnetic field generation source is rotated; and a calibration parameter calculation part for calculating calibration parameters for calibrating a rotational angle detected by the rotational angle detector, based on an output signal acquired by the acquisition part.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a calibration device, a calibration method, a rotation angle detection device, and a program.

2. Description of the Related Art Conventionally, a rotation angle detection device that detects a rotation angle of a rotating body in an XY plane by detecting a rotating magnetic field generated by a magnet or the like attached to the rotating body rotating in the XY plane is known (for example, Patent Documents). 1). In the rotation angle detection device, the rotation angle is detected using a magnetic field detection sensor that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction.
Patent Document 1 JP 2017-3312 A Non-Patent Document 1 S. Popovic, "Hall Effect Devices", Inst of Physics Pub Inc, May 1991.

  If an error occurs in the mounting position of each member in the rotation angle detection device, such as a positional deviation between the rotation axis of the magnet and the magnetic field detection sensor, an error also occurs in the detected angle.

  In the first aspect of the present invention, rotation angle detection is performed to calculate the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction on the XY plane, and detect the rotation angle in the XY plane of the magnetic field generation source rotating around the rotation axis. An apparatus calibration apparatus is provided. The rotation angle detection device is arranged with an XY magnetic field detection unit that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction, and an XY magnetic field detection unit sandwiched between the XY planes, each in the Z-axis direction perpendicular to the XY plane. And a Z magnetic field detection unit including two pairs of sensor elements for detecting a magnetic field. The calibration apparatus may include an acquisition unit that acquires an output signal corresponding to a magnetic field detection result in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated. The calibration device may include a calibration parameter calculation unit that calculates a calibration parameter for calibrating the rotation angle detected by the rotation angle detection device based on the output signal acquired by the acquisition unit.

  The rotation angle of the magnetic field generation source is θ, the output signals of one pair of sensor elements in the Z magnetic field detection unit are z1 and z3, the output signals of the other pair of sensor elements are z2 and z4, and Bz (θ) = z1−z2 + z3. It may be −z4. The calibration parameter calculation unit may calculate a calibration parameter based on a component of a single angle of the Fourier series of Bz (θ).

The magnetic field in the X-axis direction detected by the XY magnetic field detection unit may be Vx, the magnetic field in the Y-axis direction may be Vy, and the amplitude signal MAG may be MAG (θ) = sqrt (Vx ² + Vy ² ). The calibration parameter calculation unit may calculate a Fourier series corresponding to Bz (θ) based on a value obtained by normalizing Bz (θ) using the amplitude signal.

  The calibration parameter calculation unit may calculate a calibration parameter further based on a double angle component of the Fourier series of the amplitude signal. The calibration parameter calculation unit calculates the position of the XY magnetic field detection unit and the magnetic field generation source in the X-axis direction based on a component of a single angle of the Fourier series of Bz (θ) and a component of a double angle of the Fourier series of the amplitude signal. Calibration parameter Dx for correcting the rotation angle detection error caused by the deviation, calibration parameter Dy for correcting the rotation angle detection error caused by the positional deviation between the XY magnetic field detector and the magnetic field generation source, and the rotation axis of the magnetic field generation source Four calibration parameters: calibration parameter Ed for correcting rotation angle detection error caused by eccentricity in the d-axis direction, and calibration parameter Eq for correcting rotation angle detection error caused by eccentricity in the q-axis direction with respect to the rotation axis of the magnetic field generation source At least one of the calibration parameters may be calculated. Here, the eccentricity includes the inclination of the magnetic field generation source with respect to the rotation axis.

  The calibration parameter calculation unit may calculate all four calibration parameters of the calibration parameter Dx, the calibration parameter Dy, the calibration parameter Ed, and the calibration parameter Eq.

  The calibration parameter calculation unit calculates the calibration parameter when the absolute value of the 1 × square component of the Fourier series of Bz (θ) and the absolute value of the 2 × square component of the Fourier series of the amplitude signal are smaller than a predetermined value. It is not necessary to calculate.

  In the second aspect of the present invention, rotation angle detection is performed for detecting the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction on the XY plane, and calculating the rotation angle in the XY plane of the magnetic field generation source rotating around the rotation axis. An apparatus calibration method is provided. The rotation angle detection device is arranged with an XY magnetic field detection unit that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction, and an XY magnetic field detection unit sandwiched between the XY planes, each in the Z-axis direction perpendicular to the XY plane. And a Z magnetic field detection unit including two pairs of sensor elements for detecting a magnetic field. The calibration method includes an acquisition step of acquiring an output signal corresponding to a detection result in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated, and a rotation angle based on the output signal acquired in the acquisition step. A parameter calculation step of calculating a calibration parameter for calibrating the rotation angle detected by the detection device.

  In the third aspect of the present invention, rotation angle detection is performed in which a magnetic field in the XY plane is detected by detecting a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction on the XY plane. Providing equipment. The rotation angle detection device is arranged with an XY magnetic field detection unit that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction, and an XY magnetic field detection unit sandwiched between the XY planes, each in the Z-axis direction perpendicular to the XY plane. And a Z magnetic field detection unit including two pairs of sensor elements for detecting a magnetic field. The rotation angle detection apparatus includes a calibration parameter storage unit that stores calibration parameters generated based on output signals corresponding to detection results in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated. Good. The rotation angle detection device may include an angle calculation unit that calculates the rotation angle of the magnetic field generation source based on the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction detected by the XY magnetic field detection unit, and the calibration parameter.

  The rotation angle detection device may include the calibration device according to the first aspect.

  The XY magnetic field detection unit and the Z magnetic field detection unit may output a signal indicating each of the magnetic field in the X-axis direction, the magnetic field in the Y-axis direction, and the magnetic field in the Z-axis direction to an external calibration device. The calibration parameter storage unit may store calibration parameters calculated by an external calibration device.

  According to a fourth aspect of the present invention, there is provided a program for causing a computer to function as the calibration device according to the first aspect.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The structural example of the magnetic sensor 100 is shown. An example in which the first sensor pair 110 detects a magnetic field in the X-axis direction is shown. The structural example of the rotation angle detection apparatus 300 which concerns on one Embodiment of this invention is shown. An example in which the center of the rotation axis 412 is shifted from the center of the XY magnetic field detection unit is shown. An example in which the center of the rotation axis 412 is shifted in the X-axis direction and an example in which the center is shifted in the Y-axis direction with respect to the center of the XY magnetic field detection unit is shown. An example in which the center of the rotating shaft 412 is shifted from the center of the magnetic field generation source 410 is shown. An example in which the center of the rotating shaft 412 is shifted in the d-axis direction with respect to the center of the magnetic field generation source 410 is shown. An example in which the center of the rotation axis 412 is shifted in the q-axis direction with respect to the center of the magnetic field generation source 410 is shown. It is a block diagram which shows the structural example of the signal processing apparatus 200 and the calibration apparatus 250 which calculates a calibration parameter. It is a flowchart which shows the operation example of the rotation angle detection apparatus 300 in the case of calculating a calibration parameter. It is a flowchart which shows an example of the calculation method of a calibration parameter. It is a figure which shows an example of the detection magnetic field Bz ((theta)) when X shift | offset | difference and d eccentricity arise. The magnitude of the angle error between the detection angle Φ and the actual rotation angle θ is shown before and after calibration. An example in which a sensor is arranged at the center of the magnetic field generation source 410 is shown. It is a figure which shows ^Hmag (z) * _ei ( ^theta ). It is a figure explaining the case where position shift and eccentricity have arisen. It is a figure which shows the other structural example of the signal processing apparatus. An example of a hardware configuration of a computer 1900 functioning as the calibration apparatus 250 according to the present embodiment is shown.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration example of the magnetic sensor 100. The magnetic sensor 100 detects magnetism input to the magnetic sensor 100. Further, the magnetic sensor 100 may detect a change in magnetism input to the magnetic sensor 100. As an example, the magnetic sensor 100 detects a magnetic field generated by a magnetic field generation source such as a rotating magnet that rotates about a rotation axis perpendicular to the XY plane. Based on the magnetic field detected by the magnetic sensor 100, the rotation angle of the magnetic field generation source in the XY plane can be calculated.

  The magnetic sensor 100 of this example includes a substrate 10, a first sensor pair 110, a second sensor pair 120, a third sensor pair 140, a fourth sensor pair 150, and a magnetic convergence plate 130. The substrate 10 is formed of a semiconductor such as silicon and includes a semiconductor circuit and a semiconductor element. The substrate 10 may be an IC chip. In this case, the substrate 10 may include terminals that are electrically connected to an external substrate, circuit, wiring, and the like. In FIG. 1, one surface (surface) of the substrate 10 is an XY plane indicated by an X axis and a Y axis, and an axis substantially perpendicular to the XY plane is a Z axis. That is, the X, Y, and Z axes indicate examples of coordinate systems that are orthogonal to each other.

  The first sensor pair 110 and the second sensor pair 120 are an example of an XY magnetic field detection unit that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction. The first sensor pair 110 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. The first sensor pair 110 may be formed on the surface of the substrate 10. Alternatively, at least a part of the first sensor pair 110 may be embedded in the substrate 10. The first sensor pair 110 includes a first sensor element 112 and a second sensor element 114. As an example, the two sensor elements of the first sensor pair 110 are arranged along the X-axis direction. A direction from the first sensor element 112 toward the second sensor element 114 is a positive direction on the X axis.

  The first sensor element 112 and the second sensor element 114 have a function of detecting a magnetic field that is input to the sensor element in the Z-axis direction. The first sensor element 112 and the second sensor element 114 are, for example, elements that generate an electromotive force in the Y-axis direction corresponding to a magnetic field input in the Z-axis direction when a current is passed in the X-axis direction. The first sensor element 112 and the second sensor element 114 may be Hall elements that generate a Hall effect. The first sensor element 112 and the second sensor element 114 may be formed of a semiconductor or the like.

  Similar to the first sensor pair 110, the second sensor pair 120 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. The second sensor pair 120 includes a third sensor element 122 and a fourth sensor element 124. As an example, the two sensor elements of the second sensor pair 120 are arranged along the Y-axis direction. A direction from the third sensor element 122 toward the fourth sensor element 124 is a positive direction on the Y axis.

  Similar to the first sensor pair 110, the third sensor element 122 and the fourth sensor element 124 have a function of detecting a magnetic field input to the sensor element in the Z-axis direction. The third sensor element 122 and the fourth sensor element 124 are, for example, elements that generate an electromotive force in the X-axis direction corresponding to a magnetic field input in the Z-axis direction when a current is passed in the Y-axis direction. The third sensor element 122 and the fourth sensor element 124 may be Hall elements that generate a Hall effect.

  In the example of FIG. 1, a straight line connecting the first sensor element 112 and the second sensor element 114 is defined as an X axis, and a straight line connecting the third sensor element 122 and the fourth sensor element 124 is defined as a Y axis. The first sensor element 112 and the second sensor element 114 of this example are arranged symmetrically with respect to the Y axis. The third sensor element 122 and the fourth sensor element 124 of this example are arranged symmetrically with respect to the X axis. The first sensor element 112, the second sensor element 114, the third sensor element 122, and the fourth sensor element 124 in this example have the same distance to the intersection of the X axis and the Y axis (that is, the origin of the XY coordinate system). Has been placed.

  The first sensor pair 110 and the second sensor pair 120 described above may be alternately switched between energization in the X-axis direction and energization in the Y-axis direction in order to cancel the offset output. Such an offset cancellation method is known as a Spinning Current method as described in Non-Patent Document 1.

  The magnetic converging plate 130 bends the magnetic field input to the magnetic sensor 100. The magnetic flux concentrating plate 130 of this example converts the magnetic field components in the X-axis direction and the Y-axis direction input to the magnetic sensor 100 into magnetic field components in the Z-axis direction and converts them into the first sensor pair 110 and the second sensor pair 120. Let it be detected. The magnetic converging plate 130 may be formed of a magnetic material or the like. As an example, the magnetic flux concentrating plate 130 is formed of a soft magnetic material including an FeNi alloy or the like.

  The magnetic convergence plate 130 may be formed in a cylindrical shape. Each sensor element is provided at a position covered by the magnetic convergence plate 130. The magnetic flux concentrating plate 130 may be formed on the upper surface of the substrate 10, or alternatively, may be formed above the substrate 10 via an insulating layer or the like. Instead of or in addition to this, the magnetic flux concentrating plate 130 may be formed on the lower surface side of the substrate 10.

  The third sensor pair 140 and the fourth sensor pair 150 are an example of a Z magnetic field detection unit that detects a magnetic field in the Z-axis direction. Each of the third sensor pair 140 and the fourth sensor pair 150 includes two sensor elements. The two sensor elements are arranged with a magnetic converging plate 130 (or a magnetic field generation source 410 to be described later) interposed therebetween in the XY plane. Each sensor element detects a magnetic field in the Z-axis direction.

  Similar to the first sensor pair 110, the third sensor pair 140 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. The two sensor elements of the third sensor pair 140 are arranged point-symmetrically with respect to the origin of the XY coordinate system. The third sensor pair 140 includes a fifth sensor element 142 and a sixth sensor element 144. The two sensor elements of the third sensor pair 140 in the example of FIG. 1 are arranged along a straight line having an inclination of 45 degrees with respect to each of the X axis and the Y axis.

  Similar to the third sensor pair 140, the fourth sensor pair 150 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. The two sensor elements of the fourth sensor pair 150 are arranged point-symmetrically with respect to the origin of the XY coordinate system. The straight line connecting the two sensor elements of the fourth sensor pair 150 is preferably orthogonal to the straight line connecting the two sensor elements of the third sensor pair 140. The fourth sensor pair 150 includes a seventh sensor element 152 and an eighth sensor element 154. The two sensor elements of the fourth sensor pair 150 in the example of FIG. 1 have an inclination of 45 degrees with respect to the X axis and the Y axis, respectively, and are straight lines connecting the two sensor elements of the third sensor pair 140. Are arranged along a straight line having an inclination of 90 degrees.

  Similar to the first sensor pair 110, the fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 have a function of detecting a magnetic field input in the Z-axis direction. The fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 are, for example, Y corresponding to a magnetic field input in the Z-axis direction when a current is passed in the X-axis direction or the Y-axis direction. It is an element that generates an electromotive force in the axial direction or the X-axis direction. The fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 may be Hall elements that generate a Hall effect.

  The fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 are arranged so that the distances to the intersection of the X axis and the Y axis (that is, the origin of the XY coordinate system) are equal. It is preferable. Further, the fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 are sensitive to the magnetic field components in the X-axis direction and the Y-axis direction that are input to the magnetic sensor 100. It is sufficiently smaller than the sensitivity to the magnetic field component in the direction. Preferably, the sensitivity to the magnetic field components in the X-axis direction and the Y-axis direction in the fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 is zero.

  The fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 152, and the eighth sensor element 154 of this example are arranged at positions that do not overlap the magnetic convergence plate 130. The fifth sensor element 142, the sixth sensor element 144, the seventh sensor element 142, the sixth sensor element 144, the seventh sensor element 152, the eighth sensor element 154, and the fifth sensor element 142, the seventh sensor element 154, the seventh sensor element 154 are maximized. The sensor element 152 and the eighth sensor element 154 may be disposed at corners on the surface of the substrate 10.

  FIG. 2 shows an example when the first sensor pair 110 detects a magnetic field in the X-axis direction. In this example, the magnetic field in the X-axis direction input to the magnetic sensor 100 is Hx, the magnetic field in the Y-axis direction is Hy, and the magnetic field in the Z-axis direction is Hz. In FIG. 2, only the magnetic field Hx is shown. As an example, as shown by a broken line in FIG. 2, the magnetic flux concentrating plate 130 bends the magnetic flux in the X-axis direction due to the magnetic field Hx, and generates and inputs the magnetic flux in the + Z-axis direction to the first sensor element 112. Similarly, the magnetic flux concentrating plate 130 bends the input magnetic flux in the X-axis direction and causes the second sensor element 114 to generate and input a magnetic flux in the −Z-axis direction. The direction of the magnetic flux input to the first sensor element 112 and the second sensor element 114 is determined by the arrangement of the magnetic flux converging plate 130 and the input direction and position of the input magnetic field Hx vector.

  The magnetic flux concentrating plate 130, the first sensor element 112, and the second sensor element 114 are configured such that the magnetic flux generated by the magnetic field Hx is opposite to each other in the direction in which the magnetic flux is input to the first sensor element 112 and the second sensor element 114. It is desirable to arrange them so that the magnitudes of the absolute values are substantially equal. In this example, it is assumed that the magnitudes of the magnetic fluxes generated by the magnetic field Hx in the X-axis direction input to the first sensor element 112 and the second sensor element 114 are equal.

  Note that the first sensor element 112 and the second sensor element 114 also receive magnetic flux components due to the magnetic field Hy and the magnetic field Hz in the Y-axis direction and the Z-axis direction. However, the direction of the magnetic flux by the magnetic field Hy in the Y-axis direction input to the first sensor element 112 and the second sensor element 114 is the same, and the direction of the magnetic flux by the magnetic field Hz in the Z-axis direction is also the same. In this example, it is assumed that the magnitudes of the magnetic fluxes generated by the magnetic field Hy in the Y-axis direction input to the first sensor element 112 and the second sensor element 114 are equal, and the magnetic fluxes generated by the magnetic field Hz in the Z-axis direction are the first sensor element 112 and the second sensor element. It is assumed that the magnitudes input to the sensor elements 114 are equal.

In this case, the output signals x1 and x2 output from the first sensor element 112 and the second sensor element 114 are expressed by the following equations, respectively.
(Equation 1)
x1 = kx · Hx + ky · Hy + kz · Hz
x2 = −kx · Hx + ky · Hy + kz · Hz
Here, kx, ky, and kx are coefficients when Hx, Hy, and Hz are detected by the sensor elements, respectively, and are, for example, amplification factors by the magnetic convergence plate 130. The sensitivity of each sensor element is the same.

Therefore, an output signal Vx that is a difference between outputs of the first sensor element 112 and the second sensor element 114 is expressed by the following equation.
(Equation 2)
Vx = x1-x2 = 2kx · Hx

  As described above, the magnetic sensor 100 bends the input magnetic field in the X direction with the magnetic converging plate 130 and supplies the magnetic field to the first sensor element 112 and the second sensor element 114 as opposite Z direction magnetic fields. Therefore, the magnetic sensor 100 calculates the difference between the output signals of the first sensor element 112 and the second sensor element 114, thereby detecting the magnetic field component in the Z direction and determining the magnitude of the corresponding input magnetic field in the X direction. Can be acquired.

Although the first sensor pair 110 has been described with reference to FIG. 2, the same applies to the second sensor pair 120. However, since the second sensor pair 120 is arranged along the Y-axis direction, the magnetic field components in the X-axis direction and the Z-axis direction are canceled by using the difference between the outputs of the two sensor elements as an output signal. Thus, the component of the input magnetic field in the Y-axis direction can be acquired. That is, the output signal Vy that is the difference between the output signals y1 and y2 output from the third sensor element 122 and the fourth sensor element 124 is expressed by the following equation.
(Equation 3)
Vy = y1-y2 = 2ky · Hy

  The third sensor pair 140 and the fourth sensor pair 150 have sensitivity in the Z-axis direction and are arranged away from the magnetic flux concentrating plate 130. For this reason, the magnetic flux according to the magnetic field Hz in the Z-axis direction is detected without detecting the magnetic fields Hx and Hy in the X-axis direction and the Y-axis direction.

  FIG. 3 shows a configuration example of the rotation angle detection device 300 according to one embodiment of the present invention. The rotation angle detection device 300 detects the rotation angle of the detection target 400 in the XY plane. In this example, the detection target 400 is a rotating shaft 412 that is rotated by a motor 420. The rotating shaft 412 in this example is a rod-shaped shaft that is disposed substantially parallel to the Z-axis direction. The rotation shaft 412 rotates without changing its position on the XY plane.

  A magnetic field generation source 410 is fixed to the end of the rotating shaft 412. The magnetic field generation source 410 of this example is a magnet in which N and S poles are arranged side by side on the XY plane. As the rotation shaft 412 rotates, the N pole and S pole of the magnetic field generation source 410 rotate in the XY plane. As an example, the magnetic field generation source 410 has a disk-shaped outer shape in the XY plane. In the XY plane, one region obtained by equally dividing the magnetic field generation source 410 into two is the N pole, and the other region is the S pole.

  The rotation angle detection device 300 detects the rotation angle of the detection target 400 based on the magnetic field generated by the magnetic field generation source 410. In this specification, the actual rotation angle of the detection target 400 may be referred to as a rotation angle θ, and the rotation angle detected by the rotation angle detection device 300 may be referred to as a detection angle Φ.

  The rotation angle detection device 300 includes a magnetic sensor 100 and a signal processing device 200. The magnetic sensor 100 has the same configuration as the magnetic sensor 100 described with reference to FIGS. 1 and 2 and detects the magnetic field generated by the magnetic field generation source 410. The magnetic sensor 100 of this example is disposed below the magnetic field generation source 410 in the Z axis.

  The signal processing device 200 processes a signal output from each sensor element of the magnetic sensor 100. The signal processing device 200 calculates the detection angle Φ of the detection target 400 based on the output of the sensor element. At least a part of the configuration of the signal processing device 200 may be provided in the same chip as the magnetic sensor 100 or may be provided outside the chip on which the magnetic sensor 100 is provided. At least a part of the configuration of the signal processing device 200 may be formed on the same substrate 10 as the magnetic sensor 100, or may be formed on a different substrate.

When the rotation axis 412 is disposed so as to overlap the origin of the XY coordinate system, and the rotation axis 412 is connected to the center of the magnetic field generation source 410, the magnetic field generation source 410 rotates in the XY plane and The output signals Vx and Vy expressed by Equation 3 change according to the rotation angle θ. In this example, since the arrangement direction of the first sensor pair 110 and the arrangement direction of the second sensor pair 120 are shifted by 90 degrees, the output signals Vx and Vy when the magnetic field generation source 410 rotates are ideally set. Is a relationship between cos and sin. Therefore, the detection angle Φ can be calculated by the following equation.
(Equation 4)
Φ = arctan (Vy / Vx)

The output signal of the fifth sensor element 142 included in the third sensor pair 140 is z1, and the output signal of the sixth sensor element 144 is z3. The output signal of the seventh sensor element 152 included in the fourth sensor pair 150 is z2, and the output signal of the eighth sensor element 154 is z4. The signs of z1 and z3 are opposite to each other, and the signs of z2 and z4 are also opposite to each other. As an example, the output signals z1, z2, z3, and z4 are simply expressed by the following equations.
(Equation 5)
z1 = a
z2 = a
z3 = -a
z4 = -a

  The signal processing device 200 calculates the detection angle Φ of the magnetic field generation source 410 based on the output signal of each sensor element of the magnetic sensor 100. Here, when there is no error in the mounting positions of the rotation axis 412, the magnetic field generation source 410, and the magnetic sensor 100 on the XY plane, the detection angle Φ calculated using Equation 4 coincides with the actual rotation angle θ. However, if an error occurs in the mounting position, the detection angle Φ calculated by Equation 4 has an error with respect to the actual rotation angle θ.

  The signal processing device 200 corrects the error using a calibration parameter generated based on the output signals of the third sensor pair 140 and the fourth sensor pair 150. The calibration parameter may be calculated by a calibration device provided inside the signal processing device 200, or may be calculated by a calibration device provided outside the signal processing device 200.

  As an example, the calibration apparatus responds to magnetic field detection results in the first sensor pair 110, the second sensor pair 120, the third sensor pair 140, and the fourth sensor pair 150 when the magnetic field generation source 410 is rotated in the XY plane. Based on the output signal, a calibration parameter for correcting the detection angle Φ is calculated. The calibration apparatus may calculate a calibration parameter using each output signal when the magnetic field generation source 410 is rotated once in the XY plane. The calibration device may sample each output signal at a constant period while the magnetic field generation source 410 makes one round in the XY plane. In addition, the calibration apparatus may acquire the output signal by rotating the magnetic field generation source 410 a plurality of times in the XY plane.

  When there is no mounting position error as described above, the output of each sensor element of the third sensor pair 140 and the fourth sensor pair 150 is expressed by Equation 5. Therefore, the sum z1 + z3 of the outputs of the sensor elements in the third sensor pair 140 is zero regardless of the rotation angle θ, and the sum z2 + z4 of the outputs of the sensor elements in the fourth sensor pair 150 is also zero. On the other hand, when an error occurs in the mounting position, z1 + z3 does not become zero, and z2 + z4 does not become zero. More specifically, when there is no error in the mounting position, Bz (θ) = z1−z2 + z3−z4 becomes zero regardless of the rotation angle θ, but when an error occurs in the mounting position, Bz (θ) is a period. Signal.

  FIG. 4 shows an example in which the center of the rotating shaft 412 is shifted from the center of the XY magnetic field detection unit. The center of the XY magnetic field detection unit is, for example, the origin of the XY coordinate system shown in FIG. In this case, the signal Bz (θ) does not become zero, and a periodic error component is generated.

  FIG. 5 shows an example in which the center of the rotating shaft 412 is shifted in the X-axis direction and an example in which the center is shifted in the Y-axis direction with respect to the center of the XY magnetic field detection unit. In this specification, a case where the center of the rotating shaft 412 is shifted in the X-axis direction with respect to the center of the XY magnetic field detection unit may be referred to as X-shift, and a case where the center is shifted in the Y-axis direction may be referred to as Y-shift. As a result of estimating the error component by simulation, it was found that an error component appears in the component of sin θ in the Fourier series of the signal Bz (θ) when the center of the rotating shaft 412 is shifted in the X-axis direction. Similarly, it has been found that when the center of the rotating shaft 412 is shifted in the Y-axis direction, an error component appears in the component of cos θ in the Fourier series of the signal Bz (θ).

  FIG. 6 shows an example in which the center of the rotating shaft 412 is deviated from the center of the magnetic field generation source 410. That is, the rotating shaft 412 is arranged eccentrically with respect to the magnetic field generation source 410. Also in this case, the signal Bz (θ) does not become zero, and a periodic error component occurs.

  7 and 8 show an example in which the center of the rotating shaft 412 is shifted in a predetermined direction with respect to the center of the magnetic field generation source 410. FIG. In the present specification, in the magnetic field generation source 410, when θ = 0, the direction in which the S pole and the N pole are aligned (in the example of FIG. 7, coincides with the X axis direction) is the d axis and the axis orthogonal to the d axis (FIG. 7 In this example, the same as the Y-axis direction) may be referred to as the q-axis. Further, as shown in FIG. 7, when the center of the rotating shaft 412 is deviated in the d-axis direction with respect to the center of the magnetic field generation source 410, d is decentered, and when deviated in the q-axis direction as shown in FIG. May be called.

  As a result of estimating the error component by simulation, it was found that when the center of the rotating shaft 412 is decentered, an error component appears in the sin 2θ component in the Fourier series of the signal Bz (θ). Similarly, it has been found that when the rotating shaft 412 is decentered by q, an error component appears in the component of cos 2θ in the Fourier series of the signal Bz (θ).

A coefficient indicating the X shift amount is Dx, a coefficient indicating the Y shift amount is Dy, a coefficient indicating the d eccentricity amount is Ed, and a coefficient indicating the q eccentricity amount is Eq. A Fourier series Bz (FT) obtained by Fourier transforming the signal Bz (θ) is expressed as the following equation. Here, h is a coefficient corresponding to the gradient of the magnetic field.
(Equation 6)
Bz (FT) = h (Dx · sin θ + Dy · cos θ−Ed · sin 2θ
−Eq · cos 2θ)

  By detecting each component of Bz (FT) as shown in Equation 6, it is possible to estimate what mounting position deviation has occurred. The calibration device detects a mounting position shift in the rotation angle detection device 300 based on each component of the Fourier series Bz (FT) of the signal Bz (θ), and detects the detection angle detected by the rotation angle detection device 300. Calibration may be based on misalignment.

  As will be described later, the calibration device calculates each calibration parameter for calibrating the detection angle by comparing each component of the Fourier series of the amplitude signal MAG (θ) with each component of the Fourier series of the signal Bz (θ). You can do it. However, the method of calibrating the detection angle is not limited to the above example.

  Note that the magnitude of the error component appearing in the signal Bz (θ) depends on the magnetic field strength in addition to the mounting position shift amount. For this reason, when the magnetic field strength is high, the signal Bz (θ) may increase even if the amount of mounting position shift is small. For this reason, it is preferable to calculate the Fourier series Bz (FT) after the signal Bz (θ) is normalized by the magnetic field strength.

The amplitude signal MAG (θ) is defined as follows:
(Equation 7)
MAG (θ) = (Vx ² + Vy ² ) ^1/2
The calibration apparatus preferably calculates Bz (FT) by performing a Fourier transform on Bz (θ) / MAG (θ). As a result, the influence of the magnetic field strength can be eliminated, and the error component due to the mounting position shift can be detected with high accuracy.

  FIG. 9 is a block diagram illustrating a configuration example of the signal processing device 200 and the calibration device 250 that calculates the calibration parameters. In this example, the calibration device 250 is not included in the signal processing device 200, but the calibration device 250 may be included in the signal processing device 200.

  The signal processing device 200 includes an acquisition unit 210, a first signal calculation unit 220, a second signal calculation unit 230, a third signal calculation unit 232, an angle calculation unit 240, and a calibration parameter storage unit 242. The acquisition unit 210 acquires an output signal corresponding to the magnetic field detection result detected by each sensor element of the magnetic sensor 100.

  The acquisition unit 210 may be connected to the magnetic sensor 100 by wire, wireless, or a network. The acquisition unit 210 may be connected to a storage device or the like, and may acquire an output signal of the magnetic sensor 100 stored in the storage device or the like. The acquisition unit 210 supplies the acquired output signal of the magnetic sensor 100 to the first signal calculation unit 220, the second signal calculation unit 230, and the third signal calculation unit 232.

  The first signal calculation unit 220 calculates a signal Vx = x1−x2 that is a difference between output signals of the sensor elements of the first sensor pair 110. The second signal calculation unit 230 calculates a signal Vy = y1−y2 that is a difference between output signals of the sensor elements of the second sensor pair 120. The third signal calculation unit 232 calculates a signal Bz (θ) = z1−z2 + z3−z4 based on the output signals of the sensor elements of the third sensor pair 140 and the fourth sensor pair 150.

  The angle calculation unit 240 calculates the detection angle Φ of the magnetic field generation source 410 in the XY plane based on the calculation results of the first signal calculation unit 220 and the second signal calculation unit 230. The angle calculation unit 240 may calculate the detection angle Φ based on Equation 4. However, the angle calculation unit 240 calibrates the detection error of the detection angle Φ caused by the mounting position deviation based on the calibration parameter calculated by the calibration device 250. The calibration parameter may be determined for each detection angle Φ. The angle calculation unit 240 may output the calculation result to the outside.

  The calibration parameter storage unit 242 stores in advance the calibration parameters calculated by the calibration device 250. The calibration parameter storage unit 242 may store a calibration parameter indicated by a function of the detection angle Φ, and may store a table indicating the relationship between the detection angle Φ and the calibration parameter. The angle calculation unit 240 calibrates the detection angle Φ based on the calibration parameters stored in the calibration parameter storage unit 242.

  The calibration device 250 includes an acquisition unit 254 and a calibration parameter calculation unit 252. The acquisition unit 254 acquires an output signal corresponding to the magnetic field detection result in each sensor element of the magnetic sensor 100 when the magnetic field generation source 410 is rotated. The acquisition unit 254 of this example acquires Vx, Vy, and Bz (θ) calculated by the first signal calculation unit 220, the second signal calculation unit 230, and the third signal calculation unit 232 as output signals. Note that the third signal calculation unit 232 may be provided in the calibration device 250. In another example, the acquisition unit 254 may acquire the output of each sensor element of the magnetic sensor 100 as an output signal, and the signal processing device 200 performs a predetermined calculation using the output of each sensor element of the magnetic sensor 100. The calculated result may be obtained as an output signal.

  The calibration parameter calculation unit 252 calculates a calibration parameter for calibrating the detection angle Φ calculated by the angle calculation unit 240 based on the output signal acquired by the acquisition unit 254. The calibration parameter calculation unit 252 stores the calculated calibration parameter in the calibration parameter storage unit 242.

  FIG. 10 is a flowchart illustrating an operation example of the rotation angle detection device 300 when the calibration parameter is calculated. First, the magnetic field generation source 410 is rotated in the XY plane, and a rotating magnetic field is applied to the magnetic sensor 100 (S1010). In S1010, the signal processing apparatus 200 may rotate the magnetic field generation source 410 by controlling the motor 420 and the like.

  The magnetic sensor 100 detects the applied magnetic field, and the acquisition unit 254 of the calibration device 250 acquires an output signal corresponding to the detection result in the magnetic sensor 100 (S1020). Next, the calibration parameter calculation unit 252 calculates the amplitude signal MAG (θ) and the detection angle Φ based on Equation 7 and Equation 4 (S1030).

  Next, the calibration parameter calculation unit 252 calculates a calibration parameter based on the signal Bz (θ), the amplitude signal MAG (θ), and the detection angle Φ (S1040). A method for calculating the calibration parameter will be described later. Next, the calibration parameter calculation unit 252 stores the calculated calibration parameter in the calibration parameter storage unit 242 (S1050).

  FIG. 11 is a flowchart illustrating an example of a calibration parameter calculation method. Each process in the flowchart of FIG. 11 may be performed by the calibration device 250. However, part of the processing may be performed by the signal processing device 200.

  In step S1110, the magnetic field generation source 410 is rotated on the XY plane, and a rotating magnetic field is applied to the magnetic sensor 100. The calibration device 250 acquires the output signal of each sensor element for a plurality of rotation angles θ. The plurality of rotation angles θ may be rotation angles obtained by dividing one rotation (360 degrees) of the magnetic field generation source 410 at equal intervals.

  In S1112, the calibration device 250 calculates the amplitude signal MAG (θ) and the detection angle Φ using Equations 4 and 7. The calibration device 250 calculates the amplitude signal MAG and the detection angle Φ for each rotation angle θ.

  In S1114, the calibration device 250 performs a fast Fourier transform on the amplitude signal MAG (θ) using the detection angle Φ. Using the detection angle Φ means substituting Φ into θ in the amplitude signal MAG (θ). In this case, the amplitude signal MAG (θ) can be approximately Fourier transformed without using the rotation angle θ. Alternatively, the calibration device 250 may perform Fourier transform on the amplitude signal MAG (θ) without using the detection angle Φ. In this case, the calibration device 250 may acquire the rotation angle θ from a control signal of the motor 420 or the like.

In S1118, the calibration device 250 calculates the signal Bz (θ) based on the following equation. The calibration device 250 calculates a signal Bz (θ) for a plurality of rotation angles θ.
(Equation 8)
Bz (θ) = z1-z2 + z3-z4

  In S1120, the calibration device 250 normalizes the signal Bz (θ) with the amplitude signal MAG (θ). As an example, normalization refers to dividing the signal Bz (θ) by the amplitude signal MAG (θ).

  In S1122, the calibration apparatus 250 performs a fast Fourier transform on the normalized signal Bz (θ) to calculate a Fourier series Bz (FT) of the signal Bz (θ). Also in S1122, the calibration apparatus 250 may substitute Φ for θ, and may not use Φ.

Bz (FT) calculated from the output of the magnetic sensor 100 is expressed by the following equation.
(Equation 9)
Bz (FT) = α · sin θ + β · cos θ + γ · sin 2θ + δ · cos 2θ
On the other hand, the theoretical formula of Bz (FT) when an error occurs in the mounting position is given by the following formula.
(Equation 10)
Bz (FT) = h (Dx · sin θ + Dy · cos θ−Ed · sin 2θ
−Eq · cos 2θ)

Further, the Fourier series MAG (FT) of the amplitude signal MAG (θ) calculated in S1114 is expressed by the following equation.
(Equation 11)
MAG (FT) = A · cos θ + B · sin θ + C · cos 2θ + D · sin 2θ
On the other hand, the theoretical formula of MAG (FT) when an error occurs in the mounting position is given by the following formula.
(Equation 12)
MAG (FT) = − 2 (3Dx · Ed + Dy · Eq) cos θ
+2 (Dx · Eq-3Dy · Ed) sinθ
− (Dx ² −Dy ² ) cos 2θ
+ 2Dx · Dy · sin2θ
The theoretical formulas of Formula 10 and Formula 12 are examples, and other theoretical formulas can be used. For example, the theoretical formula may change depending on the relationship between the X axis and the Y axis and the d axis and the q axis. Also, the theoretical formula can change depending on the method of deriving the theoretical formula. A method for deriving the theoretical expressions of Equations 10 and 12 in this example will be described later.

The coefficients of the components of Equations 9 and 10 are equal, and the coefficients of the components of Equations 11 and 12 are equal. For this reason, the following relationship is obtained.
(Equation 13)
A = -2 (3Dx · Ed + Dy · Eq) (1)
B = 2 (Dx · Eq−3Dy · Ed) (2)
C = − (Dx ² −Dy ² ) (3)
D = 2Dx · Dy (4)
α = h · Dx (5)
β = h · Dy (6)
γ = −h · Ed (7)
δ = −h · Eq (8)

From the equations (5) and (6), the following equation is obtained.
α · β = h ² · Dx · Dy (9)
Substituting equation (4) into equation (9) yields:
α ・ β = h ²・ D / 2
h = (2α · β / D) ^1/2 (10)
Since α, β, and D are all values obtained from the measured values, the coefficient h can be calculated from Equation (10). The calibration parameter calculation unit 252 includes a Bz (FT) single-angle component (in this example, a sin θ component α and a cos θ component β) and a MAG (FT) double-angle component (in this example, a sin 2θ component). D) and the calibration parameters may be calculated on the basis of

  The calibration parameter calculation unit 252 may calculate at least a part of the calibration parameters Dx, Dy, Ed, and Eq based on the coefficient h and equations (5) to (8). The calibration parameter calculation unit 252 of this example calculates all of the calibration parameters Dx, Dy, Ed, and Eq. The calibration parameter Dx is a parameter for correcting a rotation angle detection error caused by X deviation, the calibration parameter Dy is a parameter for correcting a rotation angle detection error caused by Y deviation, and the calibration parameter Ed is obtained by d eccentricity. The calibration angle Eq is a parameter for correcting the rotation angle detection error caused by the q eccentricity.

  If the absolute values of the coefficient α = h · Dx, the coefficient β = h · Dy, and the coefficient D = 2Dx · Dy are smaller than predetermined values, it is difficult to calculate the coefficient h. . The predetermined value is a substantially zero value. In S1122, the calibration parameter calculation unit 252 determines whether the coefficient α = h · Dx, the coefficient β = h · Dy, and the coefficient D = 2Dx · Dy are substantially zero.

  When all the absolute values of the coefficient α = h · Dx, the coefficient β = h · Dy, and the coefficient D = 2Dx · Dy are substantially zero, the error of the mounting position is substantially zero. Therefore, the calibration parameter calculation unit 252 Do not calculate calibration parameters. When the absolute value of at least one of the coefficient α = h · Dx and the coefficient β = h · Dy is not substantially zero, the calibration parameter calculation unit 252 calculates Bz (FT as described in the equations (1) to (10). ) And MAG (FT) are compared to calculate the shape parameter h.

  When one absolute value of coefficient α = h · Dx and coefficient β = h · Dy is substantially zero, calibration parameter calculation unit 252 may calculate Dx or Dy based on equation (3). In this case, the calibration parameter calculation unit 252 may calculate the shape parameter h using Expression (5) or Expression (6). When the absolute values of the coefficient α = h · Dx and the coefficient β = h · Dy are not substantially zero, the calibration parameter calculation unit 252 calculates the shape parameter h based on Expression (10).

  The calibration parameter calculation unit 252 calculates calibration parameters Dx, Dy, Ed, and Eq based on the calculated shape parameter h and equations (5) to (8) (S1128). The calibration parameter calculation unit 252 may store the calculated calibration parameter in the calibration parameter storage unit 242. The calibration parameter calculation unit 252 may calculate a correction coefficient for correcting the detection angle Φ based on the calibration parameters Dx, Dy, Ed, and Eq and store the correction coefficient in the calibration parameter storage unit 242.

The correction coefficient INL (θ) of the detection angle Φ can be calculated by the following equation as an example.
(Equation 14)
INL (θ) = − 2 (Dx · Ed−Dy · Eq) sinθ
-2 (Dx · Eq + Dy · Ed) cosθ
− (Dx ² −Dy ² ) sin 2θ + 2Dx · Dy · cos 2θ
A method for deriving the correction coefficient INL (θ) will be described later.

  After the calibration parameters are stored in the calibration parameter storage unit 242, the rotation angle detection device 300 detects the rotation angle of the detection target 400 during actual operation. Specifically, the acquisition unit 210 acquires an output signal of each sensor element of the magnetic sensor 100. When detecting the rotation angle during actual operation, the output signals of the third sensor pair 140 and the fourth sensor pair 150 do not have to be acquired.

The angle calculation unit 240 detects the detection angle Φ of the detection target 400 based on the output signals Vx and Vy of the first signal calculation unit 220 and the second signal calculation unit 230. At this time, the angle calculation unit 240 may calculate the detection angle Φ based on the following equation.
(Equation 15)
Φ = arctan (Vy / Vx) −INL (θ)
Thereby, the angle detection error due to the mounting position shift can be reduced.

  FIG. 12 is a diagram illustrating an example of the detected magnetic field Bz (θ) when X deviation and d eccentricity occur. As shown in FIG. 12, when an X shift occurs, a sin θ component appears in Bz (θ). When d eccentricity occurs, a component of −sin 2θ appears in Bz (θ). When both X deviation and d eccentricity occur, a sin θ component and a −sin 2θ component are superimposed on Bz (θ). When a Y shift occurs, a cos θ component appears in Bz (θ). When q eccentricity occurs, a −cos 2θ component appears in Bz (θ).

  As described above, calibration parameters Dx, Dy, Ed, and Eq corresponding to the magnitudes of X deviation, Y deviation, d eccentricity, and q eccentricity can be extracted from each component of Bz (θ). The correction coefficient INL (θ) for the detection angle Φ can be estimated from the calibration parameters Dx, Dy, Ed, Eq.

  The third sensor pair 140 and the fourth sensor pair 150 detect a magnetic field in the Z-axis direction, whereas the first sensor pair 110 and the second sensor pair 120 detect a magnetic field in the X-axis direction and the Y-axis direction. . For this reason, the magnitude of the influence of the X deviation etc. on the detection results of the third sensor pair 140 and the fourth sensor pair 150 and the influence of the X deviation etc. on the detection results of the first sensor pair 110 and the second sensor pair 120. The sizes do not necessarily match. In this example, by comparing the components of Bz (FT) and MAG (FT), the shape parameter h indicating the relationship of the magnitude of the influence is calculated. By using the shape parameter h, the detection angle Φ can be accurately corrected based on the calibration parameters Dx, Dy, Ed, and Eq extracted based on Bz (θ).

  FIG. 13 shows the magnitude of the angle error between the detection angle Φ and the actual rotation angle θ before and after calibration. As shown in FIG. 13, by calibrating the detection angle Φ using the calibration parameters, the angle error with respect to the rotation angle θ can be made very small.

  FIGS. 14 to 16 are diagrams for explaining an example of a method for deriving theoretical expressions of MAG (θ) and INL (θ). FIG. 14 shows an example in which a sensor is arranged at the center of the magnetic field generation source 410. In FIG. 14, the two magnetic poles of the magnetic field generation source 410 are indicated by two bar magnets. The magnetic moments at both ends of each bar magnet are + m and -m, and the length is 2a. Also, let A be the distance between each bar magnet and the sensor.

磁場発生源４１０が回転した場合にセンサに入力される磁場は、次式のようにＨ_ｍａｇ（ｚ）にｅ^ｉθを乗算したものになる。
（数１７）

In this case, the magnetic field given to the sensor position (z = 0) by the two magnetic poles is expressed by the following equation.
(Equation 16)

The magnetic field input to the sensor when the magnetic field generation source 410 rotates is obtained by multiplying H _mag (z) by e ^iθ as shown in the following equation.
(Equation 17)

FIG. 15 is a diagram illustrating H _mag (z) · e ^iθ . As shown in FIG. 15, H _mag (z) · e ^iθ draws a perfect circle having a radius of 4a / A ^{2 in} the complex plane. In other words, if there is no error in the mounting position, the magnetic field vector input to the sensor draws a perfect circle according to the rotation angle θ.

なお数１９においては、実装位置の誤差がある程度小さいと仮定して、３乗までのマクローリン展開で近似している。
数１９に示すように、センサ位置における磁場には、ｅ^ｉθおよびｅ^ｉ２θの項の誤差成分が含まれている。 FIG. 16 is a diagram for explaining a case where positional deviation and eccentricity occur. The positional deviation amount D and the eccentricity amount E are expressed by the following equations.
(Equation 18)
D = Dx + iDy
E = Ed + iEq
In this case, the relative position of the sensor based on the magnetic moment appears to move by E + De− ^iθ with respect to the example of FIG. The magnetic field given to the sensor position by the two magnetic poles is expressed by the following equation.
(Equation 19)

In Equation 19, assuming that the error of the mounting position is small to some extent, the approximation is performed by Macrolin expansion up to the third power.
As shown in ^Expression 19, the magnetic field at the sensor position includes an error component in terms of e ^iθ and e ^i2θ .

数２０のように、実装位置の誤差が生じている場合、センサ位置に入力される磁場には、１次の回転ベクトル（ｅ^ｉθの項）と、２次の回転ベクトル（ｅ^ｉ２θの項）が含まれる。 When H _mag (z) in the case where there is no mounting position error is 1, and H _mag (z) of Equation 19 is normalized, the following equation is obtained.
(Equation 20)

As shown in ^Equation 20, when a mounting position error has occurred, the magnetic field input to the sensor position includes a primary rotation vector (e ^iθ term) and a secondary rotation vector (e ^i2θ term). Is included.

なお、εは実数である。円柱状の２極磁石の場合、εは磁石とセンサの距離によらずほぼ固定値となり、磁気シミュレーターを用いて推定できる。一例としてεは２程度である。 When the equation (20) is fitted using the magnetic field obtained by the magnetic simulator under the conditions shown in FIG. 16, the equation (20) can be simplified as the following equation.
(Equation 21)

Note that ε is a real number. In the case of a cylindrical dipole magnet, ε is almost a fixed value regardless of the distance between the magnet and the sensor, and can be estimated using a magnetic simulator. As an example, ε is about 2.

  The imaginary term on the right side of Equation 21 corresponds to the angle error INL (θ), and the real term corresponds to the amplitude signal MAG (θ). By substituting ε described above and calculating the imaginary term on the right side of Equation 21, INL (θ) shown in Equation 14 is obtained, and when the real term is calculated, MAG (FT) of Equation 12 is obtained.

  FIG. 17 is a diagram illustrating another configuration example of the signal processing device 200. The signal processing device 200 of this example includes a calibration device 250. The other structure may be the same as that of the signal processing apparatus 200 shown in FIG. In this case, the signal processing device 200 may function as the calibration device 250. That is, the CPU, memory, and the like of the signal processing device 200 may function as the calibration device 250.

  The rotation angle detection device 300 described with reference to FIGS. 1 to 17 can, for example, individually detect and store calibration parameters at the time of factory shipment, and then put them into the market. As a result, it is possible to supply the rotation angle detection device 300 with reduced manufacturing variations and improved accuracy.

  When the calibration device 250 is built in the signal processing device 200, the calibration device 250 may detect a calibration parameter that has changed over time. Further, the rotation angle detection device 300 may store calibration parameters for each ambient temperature. In this case, the rotation angle detection device 300 calibrates the detection angle Φ using the calibration parameter corresponding to the ambient temperature.

  FIG. 18 shows an example of a hardware configuration of a computer 1900 that functions as the calibration device 250 according to the present embodiment. The computer 1900 may function as the signal processing device 200. The computer functioning as the calibration device 250 and the computer functioning as the signal processing device 200 may be the same or different. In addition, a plurality of computers may cooperate to function as the calibration device 250, or a plurality of computers may cooperate to function as the signal processing device 200.

  A computer 1900 according to this embodiment is connected to a CPU peripheral unit having a CPU 2000, a RAM 2020, a graphic controller 2075, and a display device 2080 that are connected to each other by a host controller 2082, and to the host controller 2082 by an input / output controller 2084. An input / output unit having a communication interface 2030, a hard disk drive 2040, and a DVD drive 2060; a legacy input / output unit having a ROM 2010, a flexible disk drive 2050, and an input / output chip 2070 connected to the input / output controller 2084; Is provided.

  The host controller 2082 connects the RAM 2020 to the CPU 2000 and the graphic controller 2075 that access the RAM 2020 at a high transfer rate. The CPU 2000 operates based on programs stored in the ROM 2010 and the RAM 2020 and controls each unit. The graphic controller 2075 acquires image data generated by the CPU 2000 or the like on a frame buffer provided in the RAM 2020 and displays it on the display device 2080. Instead of this, the graphic controller 2075 may include a frame buffer for storing image data generated by the CPU 2000 or the like.

  The input / output controller 2084 connects the host controller 2082 to the communication interface 2030, the hard disk drive 2040, and the DVD drive 2060, which are relatively high-speed input / output devices. The communication interface 2030 communicates with other devices via a network. The hard disk drive 2040 stores programs and data used by the CPU 2000 in the computer 1900. The DVD drive 2060 reads a program or data from the DVD-ROM 2095 and provides it to the hard disk drive 2040 via the RAM 2020.

  The input / output controller 2084 is connected to the ROM 2010, the flexible disk drive 2050, and the relatively low-speed input / output device of the input / output chip 2070. The ROM 2010 stores a boot program that the computer 1900 executes at startup and / or a program that depends on the hardware of the computer 1900. The flexible disk drive 2050 reads a program or data from the flexible disk 2090 and provides it to the hard disk drive 2040 via the RAM 2020. The input / output chip 2070 connects the flexible disk drive 2050 to the input / output controller 2084 and inputs / outputs various input / output devices via, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like. Connect to controller 2084.

  A program provided to the hard disk drive 2040 via the RAM 2020 is stored in a recording medium such as the flexible disk 2090, the DVD-ROM 2095, or an IC card and provided by the user. The program is read from the recording medium, installed in the hard disk drive 2040 in the computer 1900 via the RAM 2020, and executed by the CPU 2000. The program is installed in the computer 1900, and causes the computer 1900 to function as each component of the calibration device 250 or each component of the signal processing device 200.

  The information processing described in the program is read into the computer 1900, whereby the acquisition unit 210, the first signal calculation unit 220, and the second are specific means in which the software and the various hardware resources described above cooperate. It functions as at least part of the signal calculation unit 230, the third signal calculation unit 232, the angle calculation unit 240, the calibration parameter storage unit 242, the calibration parameter calculation unit 252, and the acquisition unit 254. And by this specific means, the calculation or processing of the information according to the purpose of use of the computer 1900 in the present embodiment is realized, so that a specific calibration device 250 or signal processing device 200 according to the purpose of use is constructed. .

  As an example, when communication is performed between the computer 1900 and an external device or the like, the CPU 2000 executes a communication program loaded on the RAM 2020 and executes a communication interface based on the processing content described in the communication program. A communication process is instructed to 2030. Under the control of the CPU 2000, the communication interface 2030 reads transmission data stored in a transmission buffer area or the like provided on a storage device such as the RAM 2020, the hard disk drive 2040, the flexible disk 2090, or the DVD-ROM 2095, and sends it to the network. The reception data transmitted or received from the network is written into a reception buffer area or the like provided on the storage device. As described above, the communication interface 2030 may transfer transmission / reception data to / from the storage device by the DMA (Direct Memory Access) method. Instead, the CPU 2000 transfers the storage device or the communication interface 2030 as the transfer source. The transmission / reception data may be transferred by reading the data from the data and writing the data to the communication interface 2030 or the storage device of the transfer destination.

  In addition, the CPU 2000 includes all or necessary portions of files or databases stored in an external storage device such as the hard disk drive 2040, DVD drive 2060 (DVD-ROM 2095), and flexible disk drive 2050 (flexible disk 2090). Are read into the RAM 2020 by DMA transfer or the like, and various processes are performed on the data on the RAM 2020. Then, CPU 2000 writes the processed data back to the external storage device by DMA transfer or the like. In such processing, since the RAM 2020 can be regarded as temporarily holding the contents of the external storage device, in the present embodiment, the RAM 2020 and the external storage device are collectively referred to as a memory, a storage unit, or a storage device. Various types of information such as various programs, data, tables, and databases in the present embodiment are stored on such a storage device and are subjected to information processing. Note that the CPU 2000 can also store a part of the RAM 2020 in the cache memory and perform reading and writing on the cache memory. Even in such a form, the cache memory bears a part of the function of the RAM 2020. Therefore, in the present embodiment, the cache memory is also included in the RAM 2020, the memory, and / or the storage device unless otherwise indicated. To do.

  In addition, the CPU 2000 performs various operations, such as various operations, information processing, condition determination, information search / replacement, etc., described in the present embodiment, specified for the data read from the RAM 2020 by the instruction sequence of the program. Is written back to the RAM 2020. For example, when performing the condition determination, the CPU 2000 determines whether the various variables shown in the present embodiment satisfy the conditions such as large, small, above, below, equal, etc., compared to other variables or constants. When the condition is satisfied (or not satisfied), the program branches to a different instruction sequence or calls a subroutine.

  Further, the CPU 2000 can search for information stored in a file or database in the storage device. For example, in the case where a plurality of entries in which the attribute value of the second attribute is associated with the attribute value of the first attribute are stored in the storage device, the CPU 2000 displays the plurality of entries stored in the storage device. The entry that matches the condition in which the attribute value of the first attribute is specified is retrieved, and the attribute value of the second attribute that is stored in the entry is read, thereby associating with the first attribute that satisfies the predetermined condition The attribute value of the specified second attribute can be obtained.

  The program or module shown above may be stored in an external recording medium. As a recording medium, in addition to the flexible disk 2090 and the DVD-ROM 2095, an optical recording medium such as a DVD, Blu-ray (registered trademark), or a CD, a magneto-optical recording medium such as an MO, a tape medium, a semiconductor such as an IC card, etc. A memory or the like can be used. Further, a storage device such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1900 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 100 ... Magnetic sensor, 110 ... 1st sensor pair, 112 ... 1st sensor element, 114 ... 2nd sensor element, 120 ... 2nd sensor pair, 122 ... 3rd sensor element, 124 ... 4th sensor element, 130 ... Magnetic convergence plate, 140 ... 3rd sensor pair, 142 ... 5th sensor element, 144 ... 6th sensor 150, fourth sensor pair, 152, seventh sensor element, 154, eighth sensor element, 200, signal processing device, 210, acquisition unit, 220, first. Signal calculation unit, 230 ... second signal calculation unit, 232 ... third signal calculation unit, 240 ... angle calculation unit, 242 ... calibration parameter storage unit, 250 ... calibration device, 252 ..Calibration parameter calculation unit, 254... Acquisition unit, 300 .. Rotation angle detector, 400 ... detection target, 410 ... magnetic field generation source, 412 ... rotating shaft, 420 ... motor, 1900 ... computer, 2000 ... CPU, 2010 ... ROM 2020 ... RAM, 2030 ... communication interface, 2040 ... hard disk drive, 2050 ... flexible disk drive, 2060 ... DVD drive, 2070 ... input / output chip, 2075 ... graphic. -Controller, 2080 ... Display device, 2082 ... Host controller, 2084 ... Input / output controller, 2090 ... Flexible disk, 2095 ... DVD-ROM

Claims (12)

A rotation angle detection device calibration device for calculating a magnetic field in the XY plane and calculating a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction to detect a rotation angle in the XY plane of a magnetic field generation source rotating around the rotation axis,
The rotation angle detection device includes:
An XY magnetic field detector that detects the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction;
A Z magnetic field detection unit that includes two pairs of sensor elements that are arranged across the XY magnetic field detection unit in the XY plane and each detect a magnetic field in the Z-axis direction perpendicular to the XY plane;
With
The calibration device comprises:
An acquisition unit for acquiring an output signal corresponding to a magnetic field detection result in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated;
A calibration device comprising: a calibration parameter calculation unit that calculates a calibration parameter for calibrating the rotation angle detected by the rotation angle detection device based on the output signal acquired by the acquisition unit. The rotation angle of the magnetic field generation source is θ, the output signals of one pair of sensor elements in the Z magnetic field detection unit are z1 and z3, the output signals of the other pair of sensor elements are z2 and z4, and Bz (θ) = z1. -Z2 + z3-z4,
The calibration apparatus according to claim 1, wherein the calibration parameter calculation unit calculates the calibration parameter based on a component of a 1 × angle of the Fourier series of Bz (θ). When the magnetic field in the X-axis direction detected by the XY magnetic field detector is Vx, the magnetic field in the Y-axis direction is Vy, and the amplitude signal MAG is MAG (θ) = sqrt (Vx ² + Vy ² ),
The calibration apparatus according to claim 2, wherein the calibration parameter calculation unit calculates the Fourier series corresponding to the Bz (θ) based on a value obtained by normalizing the Bz (θ) using the amplitude signal. The calibration apparatus according to claim 3, wherein the calibration parameter calculation unit calculates the calibration parameter further based on a double-angle component of a Fourier series of the amplitude signal. The calibration parameter calculation unit is based on a component of a single square of the Fourier series of Bz (θ) and a component of a double square of the Fourier series of the amplitude signal.
A calibration parameter Dx for correcting a rotation angle detection error caused by a positional shift in the X-axis direction between the XY magnetic field detection unit and the magnetic field generation source;
A calibration parameter Dy for correcting a rotation angle detection error caused by a positional shift in the Y-axis direction between the XY magnetic field detection unit and the magnetic field generation source;
A calibration parameter Ed for correcting a rotation angle detection error caused by eccentricity in the d-axis direction with respect to the rotation axis of the magnetic field generation source; and
The calibration apparatus according to claim 4, wherein at least one calibration parameter of four calibration parameters of a calibration parameter Eq for correcting a rotation angle detection error caused by eccentricity in a q-axis direction with respect to a rotation axis of the magnetic field generation source is calculated. . The calibration apparatus according to claim 5, wherein the calibration parameter calculation unit calculates all four calibration parameters of the calibration parameter Dx, the calibration parameter Dy, the calibration parameter Ed, and the calibration parameter Eq. The calibration parameter calculation unit calibrates when the absolute value of a component of a Bx (θ) Fourier series and the component of a double angle of the Fourier series of the amplitude signal is smaller than a predetermined value. The calibration device according to claim 5 or 6, wherein a parameter is not calculated. A method for calibrating a rotation angle detection device that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction on an XY plane, and calculates a rotation angle in the XY plane of a magnetic field generation source that rotates around the rotation axis,
The rotation angle detection device is arranged with an XY magnetic field detection unit that detects the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction, and the XY magnetic field detection unit sandwiched between the XY planes, and each of them is on the XY plane. A Z magnetic field detection unit including two pairs of sensor elements for detecting a magnetic field in the vertical Z-axis direction,
The calibration method includes:
An acquisition step of acquiring an output signal according to a detection result in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated;
A parameter calculation step comprising: calculating a calibration parameter for calibrating the rotation angle detected by the rotation angle detection device based on the output signal acquired in the acquisition step. A rotation angle detector that detects a magnetic field in the X-axis direction and a magnetic field in the Y-axis direction on the XY plane, and calculates a rotation angle in the XY plane of a magnetic field generation source that rotates around the rotation axis,
An XY magnetic field detector that detects the magnetic field in the X-axis direction and the magnetic field in the Y-axis direction;
A Z magnetic field detection unit that includes two pairs of sensor elements that are arranged across the XY magnetic field detection unit in the XY plane and each detect a magnetic field in the Z-axis direction perpendicular to the XY plane;
A calibration parameter storage unit that stores calibration parameters generated based on output signals according to detection results in the XY magnetic field detection unit and the Z magnetic field detection unit when the magnetic field generation source is rotated;
A rotation angle detection device comprising: an angle calculation unit that calculates a rotation angle of the magnetic field generation source based on the magnetic field in the X axis direction and the magnetic field in the Y axis direction detected by the XY magnetic field detection unit, and the calibration parameter. .   The rotation angle detection device according to claim 9, further comprising the calibration device according to any one of claims 1 to 7. The XY magnetic field detection unit and the Z magnetic field detection unit output signals indicating the magnetic field in the X-axis direction, the magnetic field in the Y-axis direction, and the magnetic field in the Z-axis direction to an external calibration device,
The rotation angle detection device according to claim 10, wherein the calibration parameter storage unit stores the calibration parameter calculated by the external calibration device.   The program for functioning a computer as a calibration apparatus as described in any one of Claim 1 to 7.

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