JP2017181026A - Fault diagnosis device, rotational angle sensor, failure diagnosis method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an angular nonlinearity error of a rotational angle sensor while operating a rotational angle sensor.SOLUTION: There are provided a failure diagnosis device, a failure diagnosis method, and a program, including an acquisition part for acquiring the output of a rotational angle sensor outputting an angular signal and an amplitude signal of a rotating body according to the result of detecting the magnetic fields of a first shaft and a second shaft; a correlation signal calculation part for calculating a correlation signal between a predetermined periodic function corresponding to a failure mode of the rotational angle sensor and a measured signal based on the amplitude signal; and a failure determination part for determining whether the rotational angle sensor has a failure based on the correlation signal.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a failure diagnosis device, a rotation angle sensor, a failure diagnosis method, and a program.

Conventionally, a non-contact rotation angle sensor that detects a change in a magnetic field in the X direction and the Y direction and detects a rotation position of a rotating magnet or the like based on the detection result has been known. And since such a rotation angle sensor has an angle nonlinearity error, adjustment and calibration of an error, etc. were performed (for example, refer to patent documents 1-9).
Patent Document 1 JP 2002-71381 A Patent Document 2 JP 2011-158488 A Patent Document 3 US Patent Application Publication No. 2006/0290545 Patent Document 4 JP 9-196699 A Patent Document 5 JP 2010 JP-A-217151 Patent Document 6 JP 2010-164449 JP Patent Document 7 US Pat. No. 6,426,712 Patent Document 8 JP 2010-217150 JP Patent Document 9 JP 2012-181188 Non-patent Document 1 RS Popovic "Hall Effect Devices", Inst of Physics Pub Inc, May 1991 Non-Patent Document 2 Bilotti et al., "Monolithic Magnetic Hall Sensor Using Dynamic Quadrature Offset Cancellation", IEEE Journal of Solid-State Circuits, Vol. 32, No. 6, 1997, P. 829-836
Non-Patent Document 3 Udo Ausserlechner, “Limits of offset cancellation by the principle of spinning current Hall probe”, Proceedings of IEEE Sensors 2004, Vol. 3, P. 1117-1120
Non-Patent Document 4 Shin Ichimatsu, “Numerical calculation of elementary functions”, Education Publishing, January 1974

  However, since the angle non-linearity error fluctuates according to a change in temperature, etc., even if the sensor is adjusted at the shipping stage, an error may occur according to a change in the ambient temperature or the like if the sensor continues to operate. . In addition, the rotation angle sensor sometimes fails due to such an angle nonlinearity error, but it is difficult to determine the failure during the operation of the sensor.

  In the first aspect of the present invention, the acquisition of obtaining the output of the rotation angle sensor that outputs the angle signal and the amplitude signal of the rotating body according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis. A correlation signal calculation unit that calculates a correlation signal between a predetermined periodic function corresponding to a failure mode of the rotation angle sensor and a signal under measurement based on the amplitude signal, and based on the correlation signal, A failure diagnosis device, a failure diagnosis method, and a program are provided.

  In the second aspect of the present invention, the failure diagnosis apparatus according to the first aspect is provided, and the angle signal of the rotating body and the rotation angle are determined according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis. A rotation angle sensor that outputs a sensor failure signal is provided.

  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 rotation angle sensor 100 which concerns on this embodiment is shown. An example in which the first Hall element pair 110 according to the present embodiment detects a magnetic field in the first direction is shown. The structural example of the angle detection circuit 200 which concerns on this embodiment is shown. The structural example of the failure diagnosis apparatus 300 which concerns on this embodiment is shown. The operation | movement flow of the failure diagnosis apparatus 300 which concerns on this embodiment is shown. An example of the calculation circuit which the correlation signal calculation part 330 which concerns on this embodiment has is shown. An example of Hall electromotive force signals (V _X , V _Y ) is shown. An example of the amplitude of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of the angle nonlinearity error of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of Hall electromotive force signals (V _X , V _Y ) is shown. An example of the amplitude of the Hall electromotive force signal (V _X , V _Y ) is shown. An example of the angle nonlinearity error of the Hall electromotive force signal (V _X , V _Y ) is shown. The modification of the failure diagnosis apparatus 300 which concerns on this embodiment is shown. An example of the system concerning this embodiment is shown. An example of a hardware configuration of a computer 1900 functioning as the failure diagnosis apparatus 300 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 a rotation angle sensor 100 according to the present embodiment. The rotation angle sensor 100 detects, for example, the rotation angle of a rotating magnet that rotates around the rotation axis in the vicinity of the sensor without contact. The rotation angle sensor 100 includes a substrate 10, a first Hall element pair 110, a second Hall element pair 120, 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 includes a terminal and is electrically connected to an external substrate, circuit, wiring, and the like. In FIG. 1, one surface of the substrate 10 is an XY plane having an X axis and a Y axis, and an axis perpendicular to the XY plane is a Z axis. That is, the X, Y, and Z axes are coordinate systems orthogonal to each other.

  The first Hall element pair 110 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. As an example, the first Hall element pair 110 is arranged in the first direction. Here, the first direction in the present embodiment is the X-axis direction (first axis) in FIG. The first Hall element pair 110 includes a first Hall element 112 and a second Hall element 114, and the two Hall elements are arranged in parallel to the X axis (for example, on the X axis).

  As an example, the first Hall element 112 and the second Hall element 114 are elements that generate an electromotive force (Hall effect) in the Y-axis direction corresponding to a magnetic field input in the Z-axis direction when a current flows in the X-axis direction. . The first hall element 112 and the second hall element 114 may be formed of a semiconductor or the like.

  As an example, the first Hall element 112 and the second Hall element 114 are arranged line-symmetrically with respect to the Y axis on the substrate 10. Alternatively, the first Hall element 112 and the second Hall element 114 may be arranged point-symmetrically with respect to the origin on the substrate 10. In the present embodiment, an example in which the first Hall element 112 and the second Hall element 114 are arranged symmetrically with respect to the Y axis will be described.

  Similar to the first Hall element pair 110, the second Hall element pair 120 is formed on the substrate 10 and connected to a circuit or the like formed on the substrate 10. For example, the second Hall element pair 120 is arranged in the second direction. Here, the second direction in the present embodiment is the Y-axis direction (second axis) in FIG. The third direction is the Z-axis direction (third axis) in FIG. The second Hall element pair 120 includes a third Hall element 122 and a fourth Hall element 124, and the two Hall elements are arranged in parallel to the Y axis (for example, on the Y axis).

  As an example, the third Hall element 122 and the fourth Hall element 124 are elements that generate an electromotive force (Hall effect) in the X-axis direction corresponding to a magnetic field input in the Z-axis direction when a current flows in the Y-axis direction. . As an example, the third Hall element 122 and the fourth Hall element 124 are arranged symmetrically with respect to the X axis on the substrate 10. Alternatively, the third Hall element 122 and the fourth Hall element 124 may be arranged point-symmetrically with respect to the origin on the substrate 10. In the present embodiment, an example in which the third Hall element 122 and the fourth Hall element 124 are arranged symmetrically with respect to the X axis will be described.

  The first Hall element pair 110 and the second Hall element pair 120 may be alternately energized in the X-axis direction and in the Y-axis direction in order to cancel the offset output. Such an offset canceling method is known as a Spinning Current method as described in Non-Patent Document 5.

  The magnetic flux concentrating plate 130 is disposed above the first Hall element pair 110 and the second Hall element pair 120 and bends the magnetic field input to the rotation angle sensor 100. The magnetic converging plate 130 is formed of a magnetic material or the like, and for example, a first hole having a sensitivity in the Z-axis direction by bending a magnetic field in the X-axis direction and / or the Y-axis direction so as to generate a component in the Z-axis direction. Input is made to the element pair 110 and the second Hall element pair 120. 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.

  The above rotation angle sensor 100 outputs output signals (Hall electromotive force) from the first Hall element pair 110 and the second Hall element pair 120 to the outside. Here, output signals from the first Hall element pair 110 and the second Hall element pair 120 are output according to the rotation angle of the rotating magnet. The output signal will be described with reference to FIG.

  FIG. 2 shows an example in which the first Hall element pair 110 according to the present embodiment detects a magnetic field in the first direction. In FIG. 2, the horizontal direction (the horizontal direction of the paper surface) is the X axis, and the vertical direction (the vertical direction of the paper surface) is the Z axis direction.

Here, the magnetic field vector H (H _X , H _Y , H _Z ) input to the rotation angle sensor 100 is bent by the magnetic converging plate 130 and input to the first Hall element 112, the magnetic flux density vector B (Hall, X 1). Is expressed by the following equation using the magnetic permeability Mu (Hall, X1) at the position of the first Hall element 112. Here, the magnetic permeability Mu (Hall, X1) is a second-order tensor (matrix with 3 rows and 3 columns).

Similarly, the magnetic flux density vector B (Hall, X2) input to the second Hall element 114 is expressed by the following equation using the magnetic permeability Mu (Hall, X2) at the position of the second Hall element 114.

The first hall element 112 and the second hall element 114 detect a magnetic field in the Z-axis direction. Therefore, the first Hall element 112 and the second Hall element 114, as shown in the following equation, thereby to detect the magnetic flux density B _Z of the Z-axis direction that is bent by the magnetic flux concentrator 130.

Here, as shown in FIG. 2, an example in which a magnetic field vector H _in (H _X , 0, 0) _{in the} + X-axis direction is input above the rotation angle sensor 100 will be described. As an example, the magnetic converging plate 130 bends the input magnetic field as shown by a magnetic flux density vector B in the drawing, and causes the first Hall element 112 to input a magnetic flux in the + Z-axis direction.

Further, since the magnetic permeability of the magnetic flux concentrating plate 130 made of a magnetic material or the like is higher than the magnetic permeability of air, the magnetic flux in the magnetic converging plate 130 is compared with the magnetic flux density in the air. Density increases. For example, the magnetic flux density in the Z-axis direction at the position of the first Hall element 112 is approximately 1. as compared with the magnetic flux density obtained by multiplying the input magnetic field _HZ by the air permeability μ, as shown by the following equation. About 4 times higher.

Similarly, as an example, the magnetic flux concentrating plate 130 causes the second Hall element 114 to generate a magnetic flux in the −Z-axis direction, and the magnetic flux density in the Z-axis direction at the position of the second Hall element 114 is expressed by the following equation.

  The first Hall element 112 and the second Hall element 114 thus generate Hall electromotive force according to the magnetic flux density input in the Z-axis direction. Here, when the 1st Hall element 112 and the 2nd Hall element 114 are formed with substantially the same shape and the substantially same material, each magnetic sensitivity becomes substantially equal. Further, since the magnetic flux densities input to the first Hall element 112 and the second Hall element 114 are opposite to each other, the generated hall electromotive forces have different signs.

Therefore, when the magnetic sensitivity is S, the Hall electromotive force signal V _X of the first Hall element pair 110 is converted into the Hall electromotive force V _sig (Hall, X1) of the first Hall element 112 and the Hall electromotive force of the second Hall element 114. It can be defined as the following equation, which is the difference between the power V _sig (Hall, X2).

Thus, the rotation angle sensor 100 outputs the Hall electromotive force according to the magnetic field vector H _in (H _X , 0, 0) input in the X-axis direction by calculating the Hall electromotive force signal V _X. be able to. Further, since the Hall electromotive force signal V _X is the difference between the Hall electromotive forces of the Hall elements, the first Hall element 112 and the second Hall element 114 are in the same direction (+ Z axis direction or −Z axis direction), and The Hall electromotive force generated by the magnetic field having substantially the same absolute value is canceled out and becomes substantially zero.

That is, the rotation angle sensor 100 calculates the Hall electromotive force signal V _X , so that even if a magnetic field vector H _XZ (H _X , 0, H _Z ) in a direction parallel to the XZ plane is input, The Hall electromotive force corresponding to the magnetic field vector component H _X (H _X , 0, 0) can be calculated. The first Hall element 112 and the second Hall element 114 are insensitive to the magnetic field in the Y-axis direction, and the magnetic focusing plate 130 ideally converts the magnetic field in the Y-axis direction into the Z-axis direction. do not do. Therefore, the rotation angle sensor 100 calculates the Hall electromotive force signal V _X so that the three orthogonal components are not zero (in any direction) magnetic field vectors H _XYZ (H _X , H _Y , H _Z ). Is input, it is possible to detect the Hall electromotive force according to the component H _X (H _X , 0, 0) of the magnetic field vector in the X-axis direction.

Similarly, the second Hall element pair 120 arranged in the Y-axis direction can calculate the magnetic field in the Y-axis direction. In other words, the rotation angle sensor 100 uses the second Hall element pair 120 to calculate the Hall electromotive force signal V _Y of the following equation, so that the magnetic field vector H _XYZ (H _X , H _Y , H _Z ) is input. However, it is possible to calculate the Hall electromotive force according to the component H _Y (0, H _Y , 0) of the magnetic field vector in the Y-axis direction.

Similarly, the first Hall element 112 and the second Hall element 114 generate Hall electromotive force according to the magnetic flux density input in the Z-axis direction. Then, the Hall electromotive force signal _{V Z} of the first hall element pair 110, Hall electromotive force _V sig of the first Hall element 112 (Hall, X1) and Hall electromotive force _V sig of the second Hall element 114 (Hall, X2) May be calculated as the sum of. The rotation angle sensor 100 of the present embodiment will describe an example in which the Hall electromotive force signals V _X and V _Y are output, and the Hall electromotive force signal V _Z will be omitted, but the rotation angle sensor 100 is not related to the Hall electromotive force signal. for even V _Z, it may be output like the Hall electromotive force signal _{V X} and _{V Y.}

As described above, the rotation angle sensor 100 is based on the output signals of the first Hall element pair 110 and the second Hall element pair 120, and the X-axis component of the input magnetic field vector H _XYZ (H _X , H _Y , H _Z ). Hall electromotive force signals V _X and V _Y corresponding to H _X (H _X , 0,0) and Y axis component H _Y (0, H _Y , 0) are output. That is, the rotation angle sensor 100 can calculate the Hall electromotive force corresponding to the magnetic field in the direction parallel to the XY plane by decomposing it into an X-axis component and a Y-axis component.

The rotation angle sensor 100 can detect, for example, a magnetic field caused by rotation of a rotating magnet whose rotation axis is parallel to the Z axis in a plane parallel to the XY plane, and output a Hall electromotive force signal corresponding to the rotation angle. it can. Here, as an example, the rotation angle sensor 100 outputs a Hall electromotive force signal (V _X , V _Y ) represented by the following equation. Here, A _x and A _y are amplitude values of each signal, θ is a rotation angle of the rotating magnet, α is a non-orthogonality error between signals, and V _{os_x} and V _{os_y} are offsets of each signal.
(Equation 8)
V _X (θ) = A _x · cos (θ) + V _os — _x
V _Y (θ) = A _y · sin (θ + α) + V _{os_y}

Using the Hall electromotive force signals (V _X , V _Y ) as described above, an angle signal φ (θ) corresponding to the rotation angle θ of the rotating magnet can be calculated by the following equation as an example.
(Equation 9)
φ (θ) = tan ⁻¹ {V _Y (θ) / V _X (θ)}

  Here, it has been described that the rotation angle sensor 100 detects a magnetic field in a plane parallel to the XY plane, but a change in a magnetic field in another plane may be detected. The rotation angle sensor 100 can also detect a magnetic field in the Z-axis direction. For example, the rotation angle sensor 100 detects a magnetic field generated by rotation of a rotating magnet whose rotation axis is parallel to the Y-axis in a plane parallel to the XZ plane. A Hall electromotive force signal corresponding to the angle θ can be output. Similarly, the rotation angle sensor 100 detects a magnetic field generated by rotation of a rotating magnet whose rotation axis is parallel to the X axis in a plane parallel to the YZ plane, and outputs a Hall electromotive force signal corresponding to the rotation angle θ. You can also.

  Further, since the rotation angle sensor 100 can detect a three-dimensional magnetic field of the XYZ axes, it detects a magnetic field due to rotation in a plane that can be expressed by the XYZ axes, and outputs a Hall electromotive force signal corresponding to the rotation angle θ. can do. An example in which the rotation angle sensor 100 according to the present embodiment outputs a Hall electromotive force signal expressed by Equation (8) will be described.

In the formula (8), for example, when A _x is approximately equal to A _y , α is approximately zero, and A _x is approximately equal to A _y , that is, ideal Hall electromotive force signals (V _X , V _Y ) Is obtained, the angle signal φ (θ) in the equation (9) substantially coincides with the rotation angle θ. However, if the amplitude value difference (A _x −A _y ), the non-orthogonality error α, and the offset difference (V _{os_x} −V _{os_y} ) are not substantially zero, φ (θ) and θ do not match and φ ( The difference between θ) and θ (φ (θ) −θ) is an angle nonlinearity error of the rotation angle sensor 100.

FIG. 3 shows a configuration example of the angle detection circuit 200 according to the present embodiment. The angle detection circuit 200 performs a closed loop process so as to reduce the angle error signal ε (= φ (θ) −θ), and detects the angle signal φ (θ) of the rotation angle sensor 100. That is, the angle detecting circuit 200 includes a first pair of Hall effect devices 110 and the second Hall electromotive force signal from the Hall element pair 120 _(V X, V _Y) receives, according to the Hall electromotive force signal _(V X, V _Y) An angle signal φ (θ) is output. The angle detection circuit 200 outputs an amplitude signal A (φ) corresponding to the Hall electromotive force signal (V _X , V _Y ).

The angle detection circuit 200 includes an amplification unit 210, an amplification unit 212, an AD conversion unit 220, an AD conversion unit 222, a multiplication unit 230, a multiplication unit 232, an accumulation unit 240, an accumulation unit 242, an accumulation unit 244, a phase compensation unit 250, and A storage unit 260 is provided. Amplifying unit 210 is connected to the first Hall element pair 110 receives the Hall electromotive force signal V _X, amplified by a predetermined amplification degree. The amplification unit 210 supplies the amplified Hall electromotive force signal V _X to the AD conversion unit 220. AD conversion unit 220 is connected to the amplifying section 210, converts the Hall electromotive force signal _{V X} received into a digital signal. The AD conversion unit 220 supplies the converted digital signal V _X to the multiplication unit 230.

Similarly, the amplifier 212 is connected to a second pair of Hall effect devices 120, receives Hall electromotive force signal V _Y, amplified by a predetermined amplification degree. The amplification unit 212 supplies the amplified Hall electromotive force signal _VY to the AD conversion unit 222. The AD conversion unit 222 is connected to the amplification unit 212 and converts the received Hall electromotive force signal _VY into a digital signal. The AD conversion unit 222 supplies the converted digital signal V _Y to the multiplication unit 230.

Multiplying unit 230 multiplies the sine wave signal sin (phi) into a digital signal _{V X.} Further, the multiplier 230 multiplies the digital signal _VY by the cosine wave signal cos (φ). The multiplier 230 outputs the difference between the two multiplication results as an angle error signal ε, as shown by the following equation. Here, the amplification degree of the amplification unit 210 and the amplification unit 212 is set to 1.
(Equation 10)
ε = −sin (φ) · V _X + cos (φ) · V _Y

When the Hall electromotive force signals (V _X , V _Y ) are ideal signals, the angle error signal ε is expressed as follows. Here, the amplitude signal A = A _x = A _y .
(Equation 11)
ε = −A · sin (φ) · cos (θ) + A · cos (φ) · sin (θ)
= A · sin (θ−φ)

  The multiplier 230 supplies the calculated angle error signal ε to the integrator 240. The integrating unit 240 is connected to the multiplying unit 230, integrates the received angle error signal ε, and supplies the integrated angle error signal ε to the phase compensating unit 250.

  The phase compensation unit 250 is connected to the integration unit 240 and performs phase compensation so as to ensure the phase stability of the closed loop circuit. As an example, the angle detection circuit 200 shown in FIG. 3 is a so-called type 2 servo circuit including two integration units (time integration) in a closed loop circuit. Is an angular velocity signal that is a time derivative of the angle φ. The phase compensation unit 250 supplies the angular velocity signal to the integrating unit 242.

  The accumulator 242 is connected to the phase compensator 250 and accumulates the received angular velocity signals to generate an angle signal φ. For example, the integration unit 242 may be a circuit configured by a DCO (Digitally Controlled Oscillator) circuit and an up / down counter that performs an up / down count operation on an output signal of the DCO.

  The storage unit 260 previously stores a sine wave signal sin (φ) and a cosine wave signal cos (φ) corresponding to the plurality of angle signals φ. The storage unit 260 is connected to the integration unit 242 and supplies the multiplication unit 230 with a sine wave signal sin (φ) and a cosine wave signal cos (φ) corresponding to the received angle signal φ. That is, the storage unit 260 feeds back the corresponding sine wave signal sin (φ) and cosine wave signal cos (φ) to the multiplication unit 230 in accordance with the acquired angle signal φ.

  The angle detection circuit 200 of the present embodiment described above causes the integrating unit 242 to output the angle signal φ that is closer to θ by the feedback loop that has passed from the multiplying unit 230 to the phase compensating unit 250 and the storage unit 260. Further, the angle detection circuit 200 outputs an amplitude signal A (φ) of the angle error signal ε based on the angle signal φ.

In this case, the AD conversion unit 220 supplies the digital signal V _X converted from the Hall electromotive force signal V _X to the multiplication unit 230 and also to the multiplication unit 232. Similarly, the AD conversion unit 222 supplies the digital signal V _Y converted from the Hall electromotive force signal V _Y to the multiplication unit 230 and also to the multiplication unit 232.

Multiplying unit 232 multiplies the cosine wave signal cos (phi) into a digital signal _{V X.} Further, the multiplier 232 multiplies the digital signal _VY by the sine wave signal sin (φ). The multiplier 232 outputs the sum of two multiplication results as an amplitude signal A (φ) via the integrator 244 as shown in the following equation. Here, the amplification degree of the amplification unit 210 and the amplification unit 212 is set to 1.
(Equation 12)
A (φ) = cos (φ) · V _X + sin (φ) · V _Y

When the Hall electromotive force signals (V _X , V _Y ) are ideal signals and the angle signal φ is substantially equal to θ, the amplitude signal A (φ) is expressed as follows. Here, the amplitude signal A = A _x = A _y .
(Equation 13)
A (φ) = [A _x ² · {cos (φ)} ² + A _y ² · {sin (φ)} ² ] ^1/2 = A

As described above, the angle detection circuit 200 according to the present embodiment outputs the angle signal φ (θ) and the amplitude signal A (φ) according to the input Hall electromotive force signals (V _X , V _Y ). Then, when the Hall electromotive force signal (V _X , V _Y ) is an ideal signal, the angle detection circuit 200 can output an angle signal φ (θ) that is substantially the same as the rotation angle θ of the rotating magnet. Further, when the Hall electromotive force signal (V _X , V _Y ) is deviated from the ideal, the angle detection circuit 200 outputs an angle signal φ (θ) different from the rotation angle θ (that is, the angle nonlinearity error). (Φ (θ) −θ) becomes non-zero).

  Such angular non-linearity errors are due to mismatch in amplitude of the two Hall electromotive force signals (ie, mismatch in magnetic detection sensitivity of the first Hall element pair 110 and the second Hall element pair 120), non-orthogonality, and offset. to cause. Since these factors have temperature dependence, the angle nonlinearity error also varies according to the ambient temperature. Such temperature fluctuation of the angular non-linearity error can be measured at the manufacturing stage and the shipping stage of the rotation angle sensor 100, so that it can be measured in advance before being mounted on a system or the like, and calibration and correction can be executed. preferable. However, for example, when the rotation angle sensor 100 is deteriorated, the temperature fluctuation of such an angle nonlinearity error may exceed an error range required for a system or the like on which the rotation angle sensor 100 is mounted. It may affect the operation.

  Such deterioration of the rotation angle sensor 100, change with time, and the like are difficult to predict at the manufacturing stage and at the shipping stage. Therefore, even if the rotation angle sensor 100 is mounted on the system or the like, the angle nonlinearity It is desirable to be able to detect variations in sex errors. Therefore, the failure diagnosis apparatus according to the present embodiment detects an angle nonlinearity error based on the detection result of the rotation angle sensor 100 mounted on the system or the like, and causes deterioration, abnormal operation, failure, etc. of the rotation angle sensor 100. Diagnose.

FIG. 4 shows a configuration example of the failure diagnosis apparatus 300 according to the present embodiment. The failure diagnosis apparatus 300 detects an angle nonlinearity error based on the angle signal φ and the amplitude signal A (φ) output according to the Hall electromotive force signals (V _X , V _Y ). The failure diagnosis apparatus 300 includes an acquisition unit 310, a storage unit 320, a correlation signal calculation unit 330, and a failure determination unit 340.

  The acquisition unit 310 outputs the rotation angle sensor 100 that outputs the angle signal φ (θ) and the amplitude signal A (φ) of the rotating body according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis. To get. The acquisition unit 310 may acquire the angle signal φ and the amplitude signal A (φ) corresponding to the output of the rotation angle sensor 100 via the angle detection circuit 200 described with reference to FIG. Further, when the rotation angle sensor 100 includes the angle detection circuit 200 described with reference to FIG. 3, the acquisition unit 310 may acquire the angle signal φ and the amplitude signal A (φ) from the rotation angle sensor 100. Here, the acquisition unit 310 may acquire the output of the non-contact rotation angle sensor.

  The acquisition unit 310 may be connected to the rotation angle sensor 100, the angle detection circuit 200, or the like by wire, wireless, or a network, and may acquire the angle signal φ and the amplitude signal A (φ). The acquisition unit 310 may be connected to a storage device or the like, and may acquire the output of the rotation angle sensor 100 stored in the storage device or the like. The acquisition unit 310 supplies the acquired angle signal φ and amplitude signal A (φ) to the correlation signal calculation unit 330. In addition, the acquisition unit 310 may supply the acquired angle signal φ and amplitude signal A (φ) to the storage unit 320.

  The storage unit 320 stores a predetermined periodic function corresponding to the failure mode of the rotation angle sensor. The storage unit 320 stores a sine function and a cosine function as a periodic function. The periodic function will be described later. The storage unit 320 may store data generated by the failure diagnosis apparatus 300 and the like. The storage unit 320 may store intermediate data to be processed in the process of generating the data. Further, the storage unit 320 may supply the stored data to the request source in response to a request from each unit in the failure diagnosis apparatus 300.

  For example, when the storage unit 320 is connected to the acquisition unit 310 and receives the angle signal φ and the amplitude signal A (φ) from the acquisition unit 310, the storage unit 320 stores the angle signal φ and the amplitude signal A (φ). Then, the storage unit 320 supplies the angle signal φ and the amplitude signal A (φ) stored in response to the request from the correlation signal calculation unit 330 to the correlation signal calculation unit 330.

  Correlation signal calculation unit 330 is connected to acquisition unit 310 and storage unit 320, respectively, and a predetermined periodic function corresponding to the failure mode of rotation angle sensor 100 and a signal under measurement based on amplitude signal A (φ). A correlation signal is calculated. The correlation signal calculation unit 330 applies the value of the angle signal φ acquired by the acquisition unit 310 to the periodic function, and calculates a correlation signal using the applied periodic function and the amplitude signal A (φ).

  The correlation signal calculation unit 330 calculates the Nth power signal of the amplitude signal (N is a natural number of 1 or more) as the signal under measurement. For example, the correlation signal calculation unit 330 uses the amplitude signal A (φ) as a signal under measurement. Instead, the correlation signal calculation unit 330 may use the square of the amplitude signal A (φ) as the signal under measurement. The correlation signal calculation unit 330 supplies the calculated correlation function to the failure determination unit 340.

  The failure determination unit 340 determines failure of the rotation angle sensor 100 based on the correlation signal. For example, the failure determination unit 340 determines that the rotation angle sensor 100 has failed when the absolute value of the correlation signal exceeds a predetermined threshold. Moreover, the failure determination unit 340 may determine that the rotation angle sensor 100 has not failed when the absolute value of the correlation signal is equal to or less than a threshold value.

  The operation of the failure diagnosis apparatus 300 according to this embodiment will be described with reference to FIG. FIG. 5 shows an operation flow of the failure diagnosis apparatus 300 according to the present embodiment. The failure diagnosis apparatus 300 executes the operation flow shown in FIG. 5 and diagnoses whether or not the rotation angle sensor 100 has failed.

First, the acquisition unit 310 acquires the amplitude signal A (φ) (S400). For example, the acquisition unit 310 is connected to the integration unit 244 of the angle detection circuit 200 described with reference to FIG. 3 and acquires the amplitude signal A (φ) output from the integration unit 244. Here, the amplitude signal A (φ) acquired by the acquisition unit 310 can be approximated by the following equation.
(Equation 14)
A (φ) ≈A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= [{A _x · cos (θ) + V _{os — x} } ²
+ {A _y · sin (θ + α) + V _{os — y} } ² ] ^1/2

Next, the failure diagnosis apparatus 300 determines whether or not the offset V _{os_x} of the X axis that is the first axis is an abnormal value (S410). In this case, the correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to the failure mode of the X-axis offset and the amplitude signal.

Here, the failure diagnosis apparatus 300 sets the failure mode as a first mode in which the rotation angle sensor 100 includes an offset component of a signal corresponding to the first axial direction. When the rotation angle sensor 100 has such a failure in the first mode, the X-axis offset V _{os_x} becomes large. Therefore, the Hall electromotive force signal (V _X , V _Y ) in the equation (8) is It can be handled like an expression. Here, A _avg was an average value of A _x and A _y .
(Equation 15)
V _X (θ) = A _avg · cos (θ) + V _{os — x}
V _Y (θ) = A _avg · sin (θ)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation. Here, C _X represents a constant.
(Equation 16)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= {A _avg ² + V _{os — x} ² + 2 · A _avg · V _os — _x · cos (θ)} ^1/2
≒ C _X + V _{os_x} · cos (θ)

As described above, the amplitude signal A (θ) has a component that varies like a cosine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the cosine function cos (θ), the offset V _{os_x} of the X axis is _obtained. It is possible to detect a signal corresponding to. That is, when the failure mode is the first mode, the correlation signal calculation unit 330 calculates the correlation signal with the signal under measurement using the periodic function as a cosine of 1 × square.

More specifically, the rotation angle θ is a 360 ° (2π) cycle, and when the correlation signal calculation unit 330 discretizes the cycle by M, the correlation signal is expressed by the following equation.

  Such calculation of the correlation signal can be executed by the circuit shown in FIG. 6 as an example. FIG. 6 shows an example of a calculation circuit included in the correlation signal calculation unit 330 according to the present embodiment. The correlation signal calculation unit 330 includes a buffer memory 332, a multiplication unit 334, and an addition unit 336.

  As an example, the buffer memory 332 shows an example in which the acquired amplitude signal A (φ) is stored as data of 8 points every 45 ° corresponding to a period discretized with M = 8. That is, FIG. 6 shows an example when M in the equation (17) is set to 8.

  The multiplier 334 includes a number of multipliers corresponding to the number of buffer memories 332 (that is, a number corresponding to the resolution of the rotation angle sensor 100). The multiplier 334 is preferably connected to the storage unit 320 and the buffer memory 332 and includes at least the same number of multipliers as the number of the buffer memories 332. Each of the multipliers corresponds to a periodic function value obtained by substituting eight angle signals φ at 45 ° intervals into the periodic function received from the storage unit 320 (in the case of the first mode, a cosine function of a single angle). The value of the amplitude signal A (φ) is multiplied and the multiplication result is supplied to the adder 336.

  Here, when the storage unit 320 receives and stores the angle signal φ from the acquisition unit 310, the storage unit 320 substitutes the angle signal φ into a corresponding periodic function, and supplies the calculated periodic function value to the multiplication unit 334. May be. In the example of FIG. 6, for example, the storage unit 320 receives and stores eight angle signals φ at 45 ° intervals from the acquisition unit 310 and then substitutes them into cos (θ) that is a periodic function. These eight values are supplied to the corresponding eight multipliers of the multiplier 334, respectively.

The adder 336 is connected to the multiplier 334 and calculates the sum of the received multiplication results. The adder 336 outputs the sum of the multiplication results as a correlation signal calculation result. As described above, the correlation signal calculation unit 330 according to the present embodiment calculates the correlation signal of the amplitude signal A (φ) and the cosine function when detecting the failure mode of the first mode. It has been described using the equations (16) and (17) that such a correlation signal becomes a signal corresponding to the offset V _{os_x of the} X axis. In addition, the angle nonlinearity error in this case will be described with reference to FIGS.

FIG. 7 shows an example of the Hall electromotive force signal (V _X , V _Y ). 7, the horizontal axis shows the Hall electromotive force signal V _X of the X-axis direction, the vertical axis represents the Hall electromotive force signal V _Y of the Y-axis direction. A signal indicated by a dotted line is an ideal Hall electromotive force signal, and has a substantially circular shape on the XY plane. A signal indicated by a solid line is a Hall electromotive force signal having an X-axis offset V _{os_x} , and shows an example in which a substantially circular shape is translated in the V _X direction by a distance corresponding to the offset V _{os_x} . Next, the amplitude of the Hall electromotive force signal (V _X , V _Y ) in the example shown in FIG. 7 will be described.

FIG. 8 shows an example of the amplitude of the Hall electromotive force signal (V _X , V _Y ). In response to the rotation of the rotating magnet by 360 °, the rotation angle sensor 100 outputs a Hall electromotive force signal (V _X , V _Y ) having a period of 360 °. FIG. 8 shows Hall electromotive force signals (V _X , V _Y ) in this case, where the horizontal axis is the angular position θ of the rotating magnet and the vertical axis is the amplitude.

In the case of an ideal Hall electromotive force signal, the amplitude A is constant. However, as the Hall electromotive force signal V _X indicated by the dotted line, one of the Hall electromotive force signal V _X may include an offset V _{Os_x,} the amplitude A will vary depending on θ as indicated by one-dot chain lines. As shown in the example of FIG. 8, the fluctuation is generated by the sum of the cosine wave signal having an offset and the sine wave signal. Therefore, the fluctuation is synchronized with the cosine signal having a period of 360 °, and the fluctuation with the cosine signal having a period of 360 °. Correlation becomes stronger.

FIG. 9 shows an example of the angle nonlinearity error of the Hall electromotive force signals (V _X , V _Y ) shown in FIGS. The horizontal axis represents the angular position θ of the rotating magnet, and the vertical axis represents the angle nonlinearity error (φ−θ). For example, when the angle position θ is 0 °, the angle signal φ (0 °) calculated according to the Hall electromotive force signal (V _X = A + V _{os — x} , V _Y = 0) is also 0 °, and the angle nonlinearity error is 0 °. When the angle position θ is 90 °, the angle signal φ (90 °) calculated according to the Hall electromotive force signal (V _X = V _os — _x , V _Y = A) is smaller than 90 °, and the angle nonlinearity The error is a value smaller than 0 °.

When the angular position θ is 180 °, the angle signal φ (180 °) calculated according to the Hall electromotive force signal (V _X = −A + V _os — _x , V _Y = 0) is also 180 °, and the angle nonlinearity error Becomes 0 °. When the angular position θ is 270 °, the angle signal φ (270 °) calculated according to the Hall electromotive force signal (V _X = V _os — _x , V _Y = −A) is larger than 270 °, and the angle nonlinearity The sex error is a value greater than 0 °. Thus, the angle nonlinearity error fluctuates so as to indicate −sin (θ) with respect to the angle position θ. Since the fluctuation of the angle nonlinearity error shown in FIG. 9 and the fluctuation of the amplitude A shown in FIG. 8 are caused by the offset V _{os_x} of the Hall electromotive force signal, it is impossible to detect the fluctuation of the amplitude A from the correlation signal. This corresponds to detecting a variation in angular nonlinearity error.

  Therefore, the correlation signal calculation unit 330 calculates the correlation signal and supplies the calculation result to the failure determination unit 340 as described with reference to FIG. Then, the failure determination unit 340 can determine whether or not the magnitude of the angle nonlinearity error is abnormal by comparing the magnitude of the correlation signal with a predetermined threshold (that is, the rotation angle sensor). 100 faults can be determined).

When the determination result of the failure determination unit 340 is a failure of the rotation angle sensor 100 (S410: Yes), the failure determination unit 340 transmits a failure signal notifying that the X-axis offset V _{os_x} is abnormal to the outside ( S420). Instead of or in addition to this, the failure determination unit 340 may issue an alarm. The alarm is executed by, for example, emitting sound, light, and / or vibration. Accordingly, a system or the like equipped with the rotation angle sensor 100 or a user of the system can sense a failure during the operation of the rotation angle sensor 100.

When the determination result of the failure determination unit 340 is normal (S410: No), the failure diagnosis apparatus 300 determines whether or not the offset V _{os_y} of the Y axis that is the second axis is an abnormal value ( S430). Further, the failure diagnosis apparatus 300 may determine the offset of the Y axis after transmitting that the X axis offset V _{os_x} is abnormal.

The correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to the failure mode of the Y-axis offset and the amplitude signal. The failure diagnosis apparatus 300 sets the failure mode as a second mode in which the rotation angle sensor 100 includes a second axial offset component. When the rotation angle sensor 100 has such a failure in the second mode, the Hall electromotive force signal (V _X , V _Y ) in Equation (8) is expressed by the following equation as in the failure in the first mode: Can be handled as follows.
(Equation 18)
V _X (θ) = A _avg · cos (θ)
V _Y (θ) = A _avg · sin (θ) + V _{os_y}

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation. Here, _CY represents a constant.
(Equation 19)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= {A _avg ² + V _{os — y} ² + 2 · A _avg · V _os — _y · sin (θ)} ^1/2
≒ C _Y + V _{os_y} · sin (θ)

As described above, the amplitude signal A (θ) has a component that varies like a sine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the sine function sin (θ), the offset V _{os_y} of the Y axis is _obtained. It is possible to detect a signal corresponding to. That is, when the failure mode is the second mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement using the periodic function as a sine of 1 × square.

More specifically, the correlation signal is expressed by the following equation.

  . In the circuit shown in FIG. 6, the correlation signal is calculated by changing the coefficient corresponding to the angle every 45 ° (that is, the periodic function received from the storage unit 320) from cos (θ) to sin (θ). Can be executed. The correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the failure determination unit 340. Then, the failure determination unit 340 can determine whether or not the magnitude of the angle nonlinearity error is abnormal by comparing the magnitude of the correlation signal with a predetermined threshold (that is, the rotation angle sensor). 100 faults can be determined).

When the determination result of the failure determination unit 340 is a failure of the rotation angle sensor 100 (S430: Yes), the failure determination unit 340 transmits a failure signal that notifies the outside that the Y-axis offset V _{os_y} is abnormal ( S440). When the determination result of the failure determination unit 340 is normal (S430: No), the failure diagnosis apparatus 300 determines a difference in amplitude values (A) indicating a magnetic sensitivity mismatch between the first Hall element pair 110 and the second Hall element pair 120. It is determined whether or not _x− A _y ) is an abnormal value (S450). Moreover, the failure diagnosis apparatus 300 may determine a magnetic sensitivity mismatch after transmitting that the Y-axis offset V _{os_y} is abnormal.

The correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to the magnetic sensitivity mismatch failure mode and the amplitude signal. The failure diagnosis apparatus 300 sets the failure mode as a third mode including a magnetic sensitivity mismatch between a signal corresponding to the first axis and a signal corresponding to the second axis of the rotation angle sensor. When the rotation angle sensor 100 becomes such a failure in the third mode, the Hall electromotive force signal (V _X , V _Y ) of the equation (8) can be handled as the following equation.
(Equation 21)
V _X (θ) = {A _avg + (A _x −A _y ) / 2} · cos (θ)
V _Y (θ) = {A _avg + (A _x + A _y ) / 2} · sin (θ)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation.
(Equation 22)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
≒ A _avg + {(A _x -A _y ) / 2} · cos (2θ)

As described above, the amplitude signal A (θ) has a component that varies like a double angle cosine function in accordance with the rotation angle θ. Therefore, by taking a correlation with the double angle cosine function cos (2θ), A signal corresponding to the magnetic sensitivity mismatch (A _x -A _y ) can be detected. In other words, when the failure mode is the third mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement using the period function as a double cosine.

More specifically, the correlation signal is expressed by the following equation.

  Such correlation signal calculation can be executed by changing the coefficient corresponding to the angle of every 45 ° from cos (θ) to cos (2θ) in the circuit shown in FIG. Here, the angle nonlinearity error in this case will be described with reference to FIGS.

FIG. 10 shows an example of the Hall electromotive force signal (V _X , V _Y ). Figure 10 is similar to FIG. 7, the horizontal axis represents the Hall electromotive force signal V _X of the X-axis direction, the vertical axis represents the Hall electromotive force signal V _Y of the Y-axis direction. A signal indicated by a dotted line is an ideal Hall electromotive force signal, and has a substantially circular shape on the XY plane. A signal indicated by a solid line is a Hall electromotive force signal having a magnetic sensitivity mismatch, and shows an example in which (A _x −A _y ) / A _y is 0.1. Next, the amplitude of the Hall electromotive force signal (V _X , V _Y ) in the example shown in FIG. 10 will be described.

FIG. 11 shows an example of the amplitude of the Hall electromotive force signal (V _X , V _Y ). In response to the rotation of the rotating magnet by 360 °, the rotation angle sensor 100 outputs a Hall electromotive force signal (V _X , V _Y ) having a period of 360 °. FIG. 11 shows the Hall electromotive force signals (V _X , V _Y ) with the horizontal axis representing the angular position θ of the rotating magnet and the vertical axis representing the amplitude, as in FIG.

In the case of an ideal Hall electromotive force signal, the amplitude A is constant. However, the amplitude of the Hall electromotive force signal V _X indicated by a dotted line, when about 10% greater than the amplitude of the Hall electromotive force signal V _Y, amplitude A varies depending on θ as indicated by one-dot chain lines. As shown in the example of FIG. 11, the fluctuation is caused by the sum of a sine wave signal and a cosine wave signal having different amplitude values, so that the fluctuation is synchronized with the cosine signal having a period of 180 ° and is correlated with the double angle cosine signal. Becomes stronger.

FIG. 12 shows an example of the angular nonlinearity error of the Hall electromotive force signals (V _X , V _Y ) shown in FIGS. In FIG. 12, as in FIG. 9, the horizontal axis indicates the angular position θ of the rotating magnet, and the vertical axis indicates the angle nonlinearity error (φ−θ). For example, when the angular position θ is 0 °, the angle signal φ (0 °) calculated according to the Hall electromotive force signal (V _X = 1.1A, V _Y = 0) is also 0 °, and the angle nonlinearity error Becomes 0 °. Similarly, when the angular position θ is 90 °, 180 °, or 270 °, the angle signal φ (θ) calculated according to the Hall electromotive force signal is also 0 °, and the angle nonlinearity error is 0 °.

When the angular position θ is 45 °, the angle signal φ (45 °) calculated according to the Hall electromotive force signal (V _X = 1.1 · 2 ^−1/2 , V _Y = 2 ^−1/2 ). ) Is smaller than 45 °, and the angle nonlinearity error is smaller than 0 °. When the angular position θ is 135 °, the angle signal φ (135 calculated based on the Hall electromotive force signal (V _X = −1.1 · 2 ^−1/2 , V _Y = 2 ^−1/2 ). °) is greater than 135 °, and the angle nonlinearity error is greater than 0 °. Thus, the angle nonlinearity error fluctuates so as to indicate −sin (2θ) with respect to the angle position θ. The fluctuation of the angle nonlinearity error shown in FIG. 12 and the fluctuation of the amplitude A shown in FIG. 11 are caused by the magnetic sensitivity mismatch (A _x −A _y ) of the Hall electromotive force signal. Is detected from the correlation signal is equivalent to detecting a magnetic sensitivity mismatch (A _x -A _y ) component in the angular nonlinearity error.

  Therefore, the correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the failure determination unit 340. Then, the failure determination unit 340 can determine whether or not the magnitude of the angle nonlinearity error is abnormal by comparing the magnitude of the correlation signal with a predetermined threshold (that is, the rotation angle sensor). 100 faults can be determined).

If the determination result of the failure determination unit 340 is a failure of the rotation angle sensor 100 (S450: Yes), the failure determination unit 340 generates a failure signal that notifies that the magnetic sensitivity mismatch (A _x −A _y ) is abnormal. It transmits to the outside (S460). When the determination result of the failure determination unit 340 is normal (S450: No), the failure diagnosis apparatus 300 determines that the non-orthogonal error α between the Hall electromotive force signals (V _X , V _Y ) is an abnormal value. It is determined whether or not (S470). Moreover, the failure diagnosis apparatus 300 may determine the non-orthogonality error α after transmitting that the magnetic sensitivity mismatch is abnormal.

The correlation signal calculation unit 330 calculates a correlation signal between a predetermined periodic function corresponding to the failure mode of the non-orthogonal error and the amplitude signal. The failure diagnosis apparatus 300 sets the failure mode as a fourth mode including a non-orthogonal error between the signal corresponding to the first axis and the signal corresponding to the second axis by the rotation angle sensor 100. When the rotation angle sensor 100 becomes such a failure in the fourth mode, the Hall electromotive force signal (V _X , V _Y ) of the equation (8) can be handled as the following equation.
(Equation 24)
V _X (θ) = A _avg · cos (θ)
V _Y (θ) = A _avg · sin (θ + α)

Therefore, the amplitude signal A (θ) in the equation (14) is calculated as the following equation.
(Equation 25)
A (θ) = {V _X (θ) ² + V _Y (θ) ² } ^1/2
= A _avg · {cos ² (θ) + sin ² (θ + α)} ^1/2
≈ A _avg · [1 + α · {sin (2θ)} / 2]

  Thus, since the amplitude signal A (θ) has a component that varies like a double angle sine function in accordance with the rotation angle θ, by taking a correlation with the double angle sine function sin (2θ), A signal corresponding to the non-orthogonal error α can be detected. That is, when the failure mode is the fourth mode, the correlation signal calculation unit 330 calculates a correlation signal with the signal under measurement with the periodic function as a double angle sine.

More specifically, the correlation signal is expressed by the following equation.

  Such correlation signal calculation can be executed by changing the coefficient corresponding to the angle of every 45 ° from cos (θ) to sin (2θ) in the circuit shown in FIG. The correlation signal calculation unit 330 calculates a correlation signal and supplies the calculation result to the failure determination unit 340. Then, the failure determination unit 340 can determine whether or not the magnitude of the angle nonlinearity error is abnormal by comparing the magnitude of the correlation signal with a predetermined threshold (that is, the rotation angle sensor). 100 faults can be determined).

  When the determination result of the failure determination unit 340 is a failure of the rotation angle sensor 100 (S470: Yes), the failure determination unit 340 transmits a failure signal notifying that the non-orthogonal error α is abnormal (S480). ). When the determination result of the failure determination unit 340 is normal (S470: No), or after the failure determination unit 340 transmits that the non-orthogonal error α is abnormal, the failure diagnosis apparatus 300 determines that the angle nonlinearity error It is determined whether or not to end the determination (S490).

  When diagnosing the angle nonlinearity error continues (S490: No), the failure diagnosis apparatus 300 returns to the amplitude signal acquisition stage (S400) and continues the determination of the angle nonlinearity error. The failure diagnosis apparatus 300 stops the determination of the angle non-linearity error when the determination of the angle non-linearity error is terminated by an input from the user or the like (S490: Yes).

  As described above, the failure diagnosis apparatus 300 according to the present embodiment detects an angle nonlinearity error caused by an X-axis offset, a Y-axis offset, a magnetic detection sensitivity mismatch, and a non-orthogonality error, and is in operation. The presence or absence of a failure of the rotation angle sensor 100 can be diagnosed. Therefore, even when the rotation angle sensor 100 is mounted on the system or the like, the failure diagnosis apparatus 300 can diagnose the presence or absence of the failure, and immediately notifies the system or the like when a failure occurs and affects the system. Can be reduced.

  In the failure diagnosis apparatus 300 of the present embodiment described above, the example in which the correlation signal calculation unit 330 uses the first signal of the amplitude signal A (φ) (that is, the amplitude signal itself) as the signal to be measured has been described. Instead, the correlation signal calculation unit 330 may use a square signal of the amplitude signal A (φ) as the signal under measurement.

In this case, the signal under measurement shown by the equation (16) is calculated as the following equation.
(Equation 27)
A ² (θ) = V _X (θ) ² + V _Y (θ) ²
= A _avg ² + V _{os_x} ² + 2 · A _avg · V _{os_x} · cos (θ)

Since the signal under measurement A ² (θ) has a component that varies like a cosine function in accordance with the rotation angle θ, by taking a correlation with the cosine function cos (θ), it corresponds to the X-axis offset V _{os_x} . Signal can be detected. A specific correlation signal is expressed by the following equation.

Similarly, the signal under measurement shown by the equation (19) is calculated as the following equation.
(Equation 29)
A ² (θ) = V _X (θ) ² + V _Y (θ) ²
= A _avg ² + V _{os_y} ² + 2 · A _avg · V _{os_y} · sin (θ)

Since the signal under measurement A ² (θ) has a component that varies like a sine function in accordance with the rotation angle θ, by taking a correlation with the sine function sin (θ), the signal under measurement A ² (θ) corresponds to the offset V _{os_y} of the Y axis. Signal can be detected. A specific correlation signal is expressed by the following equation.

Similar to the failure modes of the first mode and the second mode described above, in the third mode and the fourth mode, the signal under measurement A ² (θ) may be the signal under measurement. In this case, the periodic function corresponding to the failure mode may be a periodic function when the signal under measurement is A (θ). In this case, the correlation signal of the third mode shown in (Expression 23) is expressed by (Expression 31), and the correlation signal of the fourth mode shown in (Expression 26) is expressed by (Expression 32). As shown.

  As described above, the correlation signal calculation unit 330 can calculate the periodic function corresponding to the signal under measurement and the failure mode for each mode. Therefore, the correlation signal calculator 330 can also calculate the Nth power signal of the amplitude signal A (φ) as the signal under measurement.

  In addition, the failure diagnosis apparatus 300 according to the present embodiment has been described as having the failure modes from the first mode to the fourth mode. Instead, the failure diagnosis apparatus 300 may have at least one of the failure modes from the first mode to the fourth mode, and diagnose a failure in at least one mode.

  In addition, the failure diagnosis apparatus 300 according to the present embodiment has been described as being connected to the rotation angle sensor 100 via the angle detection circuit 200. Instead of this, the failure diagnosis apparatus 300 may be provided in the rotation angle sensor 100. In this case, it is desirable that the failure diagnosis apparatus 300 is provided in the rotation angle sensor 100 together with the angle detection circuit 200. That is, the rotation angle sensor 100 includes the failure diagnosis apparatus 300, and according to the detection results of the magnetic field of the first axis and the magnetic field of the second axis, the angle signal of the rotating body, the amplitude signal, and the rotation angle sensor 100 Output a fault signal.

  Further, the failure diagnosis apparatus 300 according to the present embodiment is connected to the angle detection circuit 200 shown in FIG. Since failure diagnosis apparatus 300 can diagnose a failure if angle signal φ and amplitude signal A (φ) can be acquired, angle detection circuit 200 is not limited to the example of FIG. For example, the angle detection circuit 200 may be a calculation circuit based on a trigonometric function calculation model.

  FIG. 13 shows a modification of the failure diagnosis apparatus 300 according to the present embodiment. The failure diagnosis apparatus 300 of the present modification obtains the angle signal φ and the amplitude signal A (φ) from the angle calculation circuit 500. The angle calculation circuit 500 includes an amplification unit 510, an amplification unit 512, an AD conversion unit 520, an AD conversion unit 522, and a CORDIC circuit unit 530. The amplification unit 510, amplification unit 512, AD conversion unit 520, and AD conversion unit 522 perform substantially the same operations as the amplification unit 210, amplification unit 212, AD conversion unit 220, and AD conversion unit 222 described in FIG. Therefore, the description is omitted here.

  A CORDIC (Coordinating Rotation Digital Computing) circuit unit 530 generates an angle signal φ and an amplitude signal A (φ) from a Hall electromotive force signal, which is an input signal, based on an algorithm that performs various operations such as trigonometric functions, multiplication, and division. calculate. The CORDIC circuit unit 530 may be an integrated circuit such as a field-programmable gate array (FPGA) on which the CORDIC algorithm is mounted, and an application specific integrated circuit (ASIC).

  The CORDIC circuit unit 530 executes a predetermined CORDIC algorithm to calculate the angle signal φ and the amplitude signal A (φ). Here, it is known that the CORDIC circuit unit 530 outputs an amplitude signal that is about 1.6 times larger than the amplitude signal output by the angle detection circuit 200 shown in FIG.

  However, since the correlation signal calculation unit 330 according to the present embodiment calculates the correlation between the signal under measurement based on the amplitude signal and a predetermined periodic function corresponding to the failure mode, the amplitude signal is (1.6 times). Correlation signals that have almost no effect even if they become a constant multiple (about) are calculated. Therefore, the failure diagnosis apparatus 300 according to this modification can diagnose a failure of the rotation angle sensor 100 with substantially the same operation as the failure diagnosis apparatus 300 described with reference to FIGS.

  It has been described that the failure diagnosis apparatus 300 of the present embodiment described above may be a device independent of the rotation angle sensor 100 and may be a part of the rotation angle sensor 100 instead. Instead of this, the failure diagnosis apparatus 300 may be a part of a system or the like in which the rotation angle sensor 100 is mounted. Moreover, the failure diagnosis apparatus 300 may be a part of a control circuit that controls the system or the like.

  FIG. 14 shows an example of a system according to the present embodiment. The system controls other devices and the like according to the operation of the rotating body while stably controlling the rotating body such as a rotating magnet. The system is, for example, a motor control system used for electric power steering of a passenger car, a steering angle sensing system that detects the rotation angle of the steering of the passenger car, and the like. The system includes a sensor IC 140, a control unit 600, and a system unit 610.

  The sensor IC 140 includes the rotation angle sensor 100. The sensor IC 140 may further include an angle detection circuit 200 or an angle calculation circuit 500. The sensor IC 140 supplies the control unit 600 with an angle signal φ and an amplitude signal A (φ) of a rotor such as a motor rotor, steering wheel, and wheels.

  The control unit 600 is connected to the sensor IC 140 and controls a rotating system including a rotating mechanism in accordance with the angle signal φ and the amplitude signal A (φ). The control unit 600 may be an integrated circuit such as a microcomputer and a microprocessor, and has a function of executing an input program. As part of the program, the controller 600 calculates a signal under measurement based on the amplitude signal A (φ), calculates a correlation signal between the signal under measurement and a predetermined periodic function, and based on the correlation signal And a program for judging a failure of the rotation angle sensor 100.

  That is, the control unit 600 determines a failure of the rotation angle sensor 100 while controlling the rotation system. The control unit 600 supplies failure information to the system unit 610 when the determination result is failure. The system unit 610 is connected to the control unit 600 and controls system stop, interruption, alarm generation, and the like in response to receiving failure information. As a result, even if a failure occurs in the rotation angle sensor 100, the system according to the present embodiment can quickly stop or interrupt the system before seriously affecting the system operation.

  In the failure diagnosis apparatus 300 of the present embodiment described above, the example in which the rotation angle sensor 100 includes the first Hall element pair 110 and the second Hall element pair 120 has been described. Here, the failure diagnosis apparatus 300 diagnoses the failure of the rotation angle sensor that outputs the angle signal and the amplitude signal of the rotating body according to the detection result of the magnetic field of the first axis and the magnetic field of the second axis. The magnetic field detection element is not limited to a Hall element. For example, the rotation angle sensor 100 may include a plurality of GMR (Giant Magneto-Resistance) elements and / or TMR (Tunnel Magneto-Resistance) elements that detect the magnetic field of the first axis and the magnetic field of the second axis. Good.

  FIG. 15 shows an example of a hardware configuration of a computer 1900 that functions as the failure diagnosis apparatus 300 according to the present embodiment. 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 the acquisition unit 310, the storage unit 320, the correlation signal calculation unit 330, and the failure determination unit 340.

  The information processing described in the program is read into the computer 1900, whereby the acquisition unit 310, the storage unit 320, and the correlation signal calculation unit 330 are specific means in which the software and the various hardware resources described above cooperate. And function as a failure determination unit 340. And by this specific means, the calculation or processing of information according to the purpose of use of the computer 1900 in the present embodiment is realized, so that a specific failure diagnosis apparatus 300 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 Rotation angle sensor, 110 1st Hall element pair, 112 1st Hall element, 114 2nd Hall element, 120 2nd Hall element pair, 122 3rd Hall element, 124 4th Hall element, 130 Magnetic convergence plate , 140 sensor IC, 200 angle detection circuit, 210 amplification unit, 212 amplification unit, 220 AD conversion unit, 222 AD conversion unit, 230 multiplication unit, 232 multiplication unit, 240 accumulation unit, 242 accumulation unit, 244 accumulation unit, 250 phase Compensation unit, 260 storage unit, 300 failure diagnosis device, 310 acquisition unit, 320 storage unit, 330 correlation signal calculation unit, 332 buffer memory, 334 multiplication unit, 336 addition unit, 340 failure determination unit, 500 angle calculation circuit, 510 amplification , 512 amplifier, 520 AD converter, 522 AD converter, 530 ORDIC circuit section, 600 control section, 610 system section, 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 graphics Controller, 2080 Display device, 2082 Host controller, 2084 I / O controller, 2090 Flexible disk, 2095 DVD-ROM

Claims (15)

An acquisition unit that acquires an output of a rotation angle sensor that outputs an angle signal and an amplitude signal of a rotating body according to detection results of a magnetic field of a first axis and a magnetic field of a second axis;
A correlation signal calculation unit for calculating a correlation signal between a predetermined periodic function corresponding to a failure mode of the rotation angle sensor and a signal under measurement based on the amplitude signal;
A failure determination unit for determining failure of the rotation angle sensor based on the correlation signal;
A failure diagnosis apparatus comprising:   The failure diagnosis apparatus according to claim 1, wherein the failure determination unit determines that the rotation angle sensor has failed when an absolute value of the correlation signal exceeds a predetermined threshold.   The failure diagnosis apparatus according to claim 2, wherein the failure determination unit determines that the rotation angle sensor has not failed when the absolute value of the correlation signal is equal to or less than the threshold value. The failure mode is
A first mode in which the rotation angle sensor includes an offset component of a signal corresponding to the first axial direction;
A second mode in which the rotation angle sensor includes an offset component in the second axial direction;
A third mode in which the rotational angle sensor includes a magnetic sensitivity mismatch between a signal corresponding to the first axis and a signal corresponding to the second axis;
A fourth mode in which the rotation angle sensor includes a non-orthogonal error between a signal corresponding to the first axis and a signal corresponding to the second axis;
The fault diagnosis apparatus according to claim 1, wherein the fault diagnosis apparatus has at least one mode. The correlation signal calculation unit
When the failure mode is the first mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of 1 × square,
When the failure mode is the second mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of 1 ×
When the failure mode is the third mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of a double angle,
The failure diagnosis apparatus according to claim 4, wherein when the failure mode is the fourth mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of a double angle.   6. The fault diagnosis apparatus according to claim 1, wherein the correlation signal calculation unit calculates an N-th power signal (N is a natural number of 1 or more) of the amplitude signal as the signal under measurement.   The fault diagnosis apparatus according to claim 1, wherein the acquisition unit acquires an output of a non-contact rotation angle sensor. A failure diagnosis apparatus according to any one of claims 1 to 7,
According to the detection results of the magnetic field of the first axis and the magnetic field of the second axis, an angle signal of the rotating body and a failure signal of the rotation angle sensor are output.
Rotation angle sensor. A rotation angle sensor failure diagnosis method for outputting an angle signal and an amplitude signal of a rotating body according to detection results of a magnetic field of a first axis and a magnetic field of a second axis,
Obtaining the output of the rotation angle sensor;
Calculating a correlation signal between a predetermined periodic function corresponding to a failure mode of the rotation angle sensor and a signal under measurement based on the amplitude signal;
A failure of the rotation angle sensor is determined based on the correlation signal.
Fault diagnosis method. Determining the failure includes
The failure diagnosis method according to claim 9, further comprising: determining that the rotation angle sensor has failed when an absolute value of the correlation signal exceeds a predetermined threshold value. Determining the failure includes
The fault diagnosis method according to claim 10, further comprising: determining that the rotation angle sensor is not faulty when an absolute value of the correlation signal is equal to or less than the threshold value. The failure mode is
A first mode in which the rotation angle sensor includes an offset component in the first axial direction;
A second mode in which the rotation angle sensor includes an offset component in the second axial direction;
A third mode in which the rotational angle sensor includes a magnetic sensitivity mismatch between the first axis and the second axis;
A fourth mode in which the rotation angle sensor includes a non-orthogonal error;
The fault diagnosis method according to any one of claims 9 to 11, which has at least one mode. Calculating the correlation signal is
When the failure mode is the first mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of 1 × square,
When the failure mode is the second mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of 1 ×
When the failure mode is the third mode, a correlation signal with the signal under measurement is calculated using the periodic function as a cosine of a double angle,
The failure diagnosis method according to claim 12, wherein when the failure mode is the fourth mode, a correlation signal with the signal under measurement is calculated using the periodic function as a sine of a double angle.   A program for causing a computer to execute the failure diagnosis method according to any one of claims 9 to 13.   A medium for storing the program according to claim 14.

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