JP2021191136A - Correction method of rotation angle arithmetic device, rotation angle arithmetic device, motor control device, electric actuator product and electric power steering device - Google Patents

Abstract

To correct a linearity error of a rotation angle, measured by a rotation angle arithmetic device with a simple method without using external measurement means.SOLUTION: A rotation angle arithmetic device comprises: a sensor 20 that outputs a detection signal in accordance with a rotation of a rotating body; a rotation angle arithmetic unit 51 that performs arithmetic operation of a rotation angle of the rotating body on the basis of the detection signal; an angular speed arithmetic unit 72 that performs arithmetic operation of an angular speed of the rotating body on the basis of the rotational angle arithmetically operated at a plurality of times in a period when the rotating body is rotated in inertia; a theoretical value arithmetic unit 73 that performs arithmetic operation of a theoretical value of the rotation angle on the basis of the arithmetically operated angular speed; and an angle correction unit 52 that corrects the rotation angle arithmetically operated by the rotation angle arithmetic unit 51 on the basis of a difference between the rotation angle arithmetically operated by the rotation angle arithmetic unit 51 and the theoretical value arithmetically operated by the theoretical value arithmetic unit 73.SELECTED DRAWING: Figure 7

Description

The present invention relates to a correction method for a rotation angle calculation device, a rotation angle calculation device, a motor control device, an electric actuator product, and an electric power steering device.

A rotation angle calculation device for calculating the rotation angle of a rotating body is known. For example, Patent Document 1 below describes a rotation angle sensor that outputs the rotation angle of a motor.

Japanese Unexamined Patent Publication No. 2009-204479

The rotation angle measured by the rotation angle calculation device is required to change linearly with respect to a change in the actual rotation angle of the rotating body. However, the actual rotation angle calculation device has an error that the measured rotation angle deviates from the ideal straight line, that is, a linearity error (linearity error).
The linearity error can be removed by calibrating the calculation result of the rotation angle arithmetic unit based on the known rotation angle measured separately.

However, in this case, an external measuring means for separately measuring the rotation angle of the rotating body is required.
The present invention has been made in view of such a problem, and an object of the present invention is to correct a linearity error of a rotation angle measured by a rotation angle calculation device by a simple method without using an external measuring means. And.

According to one aspect of the present invention, there is provided a correction method of a rotation angle calculation device that calculates the rotation angle of the rotating body based on the detection signal output from the sensor according to the rotation of the rotating body. In this correction method, the rotation angle is calculated based on the detection signal output from the sensor at a plurality of times during the period during which the rotating body is coasting, and the rotation angle is calculated based on the calculated rotation angle. The angular velocity of the rotating body is calculated, the theoretical value of the rotation angle is calculated based on the calculated angular velocity, and the detection signal is based on the difference between the rotation angle calculated based on the detection signal and the theoretical value. The rotation angle calculated based on the above is corrected.

The rotation angle calculation device according to another aspect of the present invention includes a sensor that outputs a detection signal according to the rotation of the rotating body, a rotation angle calculation unit that calculates the rotation angle of the rotating body based on the detection signal, and rotation. An angular speed calculation unit and an angular speed calculation unit that calculate the angular speed of the rotating body based on the rotation angle calculated based on the detection signal output from the sensor at a plurality of times during the period in which the body is coasting. The difference between the theoretical value calculation unit that calculates the theoretical value of the rotation angle based on the angular velocity calculated by the unit, the rotation angle calculated by the rotation angle calculation unit, and the theoretical value calculated by the theoretical value calculation unit. Based on the above, an angle correction unit for correcting the rotation angle calculated by the rotation angle calculation unit is provided.

According to still another embodiment of the present invention, the rotation angle calculation device for calculating the rotation angle of the rotation axis of the motor as a rotating body and the motor according to the rotation angle of the rotation axis corrected by the angle correction unit. A motor control device comprising a drive unit for driving the
According to still another embodiment of the present invention, there is provided an electric actuator product comprising the motor control device described above and a motor controlled by the motor control device.
According to still another aspect of the present invention, the motor control device and the motor controlled by the motor control device are provided, and the steering assist force is applied to the steering system of the vehicle by the motor. Given an electric power steering device.

According to the present invention, the linearity error of the rotation angle measured by the rotation angle calculation device can be corrected by a simple method without using an external measuring means.

It is an exploded view which shows the outline of the example of the rotation angle calculation device of an embodiment. It is a schematic block diagram of the rotation angle arithmetic unit of embodiment. It is explanatory drawing of an example of the functional structure of the control device shown in FIG. It is explanatory drawing of an example of the functional structure of the detection signal correction part shown in FIG. (A) to (c) are explanatory diagrams of offset error, amplitude error, and phase error of a sine signal and a cosine signal, respectively. It is explanatory drawing of the angle correction data Ca. It is explanatory drawing of an example of the functional structure of the angle correction part shown in FIG. (A) is a diagram showing an example of an angle error included in the measurement angle, and (b) is a diagram showing an example of a measurement angle including the angle error of (a). (A) is an explanatory diagram of the calculation method of the angle linearity error, and (b) is an explanatory diagram of a time interval in which the measurement angle changes by 360 degrees. It is a flowchart of an example of the rotation angle calculation method of an embodiment. It is explanatory drawing of an example of the functional structure of the control device of a modification. (A) is an explanatory diagram of an example of an angular velocity change during inertial rotation, (b) is an explanatory diagram of an example of an angular velocity change during inertial rotation, and (c) is a theoretical value angle used in the first embodiment. It is explanatory drawing of an example of an error. (A) is a diagram showing an example of an angular velocity and an average angular velocity calculated from a measurement angle, and (b) is a diagram showing an example of an estimated angle and a measurement angle calculated from the average angular velocity. It is explanatory drawing of an example of the calculation method of an angular linearity error. It is a flowchart of an example of the calculation method of the angle linearity error. It is a schematic block diagram of an example of the electric power steering apparatus provided with the rotation angle calculation apparatus of embodiment.

Embodiments of the present invention will be described in detail with reference to the drawings.
It should be noted that the embodiments of the present invention shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the configuration, arrangement, etc. of components. Is not specified as the following. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims described in the claims.

(First Embodiment)
(composition)
See FIG. The rotation angle calculation device of the embodiment calculates the rotation angle of the rotation shaft 11 of the motor 10. The object of the present invention is not limited to the rotation angle calculation device that calculates the rotation angle of the rotation shaft 11 of the motor 10. The present invention can also be applied to a rotation angle calculation device that calculates the rotation angles of various rotating bodies other than the rotation shaft 11 of the motor 10.
The rotation angle calculation device includes a sensor unit 20 and a control device 30.
The sensor unit 20 outputs a detection signal corresponding to the rotation of the rotating shaft 11 to the control device 30. The sensor unit 20 includes a magnet 21, a circuit board 22, and a support member 23.

The magnet 21 is fixed to an end portion 14 opposite to the output end 12 of the rotating shaft 11 of the motor 10 and has different magnetic poles (S pole and N pole) arranged along the circumferential direction of the rotating shaft 11. There is.
An MR (Magnetic Resistance) sensor element (Integrated Circuit) 24 for detecting magnetic flux is mounted on the circuit board 22. A plurality of MR sensor elements may be mounted on the circuit board 22 to form a redundant system in which the rotation axis 11 is calculated separately based on the detection signal of each MR sensor element.

The circuit board 22 is fixed to the support member 23 by fixing means such as a fastening screw or caulking (not shown). Further, the support member 23 is also fixed to the motor 10 by a fixing means (not shown).
The position where the circuit board 22 is fixed to the support member 23 and the position where the support member 23 is fixed to the motor 10 are when the circuit board 22 is fixed to the support member 23 and the support member 23 is fixed to the motor 10. The circuit board 22 is arranged between the support member 23 and the motor 10, and the MR sensor element 24 is determined to be close to the magnet 21.

As a result, the MR sensor element 24 detects the change in the magnetic flux of the magnet 21 according to the rotation angle when the magnet 21 rotates with the rotation of the rotation shaft 11 of the motor 10, and responds to the rotation of the rotation shaft 11 of the motor 10. Output the detection signal.
For example, the MR sensor element 24 outputs a sine signal sin θ and a cosine signal cos θ corresponding to the rotation angle θ of the rotation shaft 11 of the motor 10 as detection signals corresponding to the rotation of the rotation shaft 11 of the motor 10.
The sensor used by the rotation angle calculation device of the present invention is not limited to the MR sensor. The rotation angle calculation device of the present invention may detect the rotation angle θ of the rotation shaft 11 of the motor 10 by a sensor of a method other than the MR sensor.

The support member 23 is, for example, a cover that covers the circuit board 22. The support member 23 has, for example, a recess that opens downward in FIG. 1, and the circuit board 22 is fixed in the recess of the support member 23. When the support member 23 is fixed to the motor 10, the opening of the recess of the support member 23 is shielded by the motor 10, and the circuit board 22 is housed in the recess of the support member 23 and the internal space defined by the motor 10. As a result, the circuit board 22 is protected from external impacts and foreign matter.
The support member 23 may be formed of a metal having good thermal conductivity such as an aluminum alloy and may serve as a heat sink. Further, the support member 23 may be the heat sink itself.

The control device 30, which is an electronic control unit (ECU) separate from the sensor unit 20, is connected to the sensor unit 20 by a harness 25. The detection signal output from the MR sensor element 24 in response to the rotation of the rotating shaft 11 of the motor 10 is transmitted to the control device 30 via the harness 25.
The control device 30 calculates the rotation angle θ of the rotation shaft 11 of the motor 10 based on the detection signal by the MR sensor element 24, controls the power semiconductor switching element according to the calculated rotation angle θ, and drives the motor 10. do.

See FIG. The control device 30 includes a processor 31 such as a CPU (Central Processing Unit) and an MPU (Micro-Processing Unit), a storage device 32 such as a memory, and analog digital converters (ADCs) 33 and 34. , And a drive circuit 35.
The function of the control device 30 described below is realized, for example, by the processor 31 executing a computer program stored in the storage device 32.

The control device 30 may be formed by, in addition to or in place of the processor 31, dedicated hardware for executing each information processing described below.
For example, the control device 30 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the control device 30 may have a programmable logic device (PLD: Programmable Logic Device) such as a field-programmable gate array (FPGA).

As described above, the MR sensor element 24 detects the magnetic flux of the magnet 21 that rotates together with the rotating shaft 11 of the motor 10, so that the sinusoidal signal SIN = sinθ and the cosine signal corresponding to the rotation angle θ of the rotating shaft 11 of the motor 10 COS = cosθ is output.
The control device 30 reads the sinusoidal signal SIN and the cosine signal COS converted into digital signals by the ADC 33 and the ADC 34.

The control device 30 has at least two operation modes, a "normal mode" for controlling the motor 10 and a "correction mode" for calculating various correction data used for calculating the rotation angle θ of the rotation shaft 11.
In the normal mode, the control device 30 calculates a measured value of the rotation angle θ of the rotation shaft 11 of the motor 10 (hereinafter referred to as “measurement angle θm”) based on the sine signal SIN and the cosine signal COS. Further, the control device 30 calculates the corrected measurement angle θc by correcting the measurement angle θm, controls the drive circuit 35 (for example, an inverter or the like) according to the corrected measurement angle θc, and drives the motor 10.

On the other hand, in the correction mode, the control device 30 collects the sinusoidal signal SIN, the cosine signal COS, and the measurement angle θm in order to calculate the correction data.
First, the control device 30 drives the motor 10 to rotate the rotating shaft 11. The control device 30 stores the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 in the storage device 32 while the motor 10 is rotating.
Then, the control device 30 corrects the detection signal correction data Cs1 to Cs4 for correcting the sine signal SIN and the cosine signal COS output by the MR sensor element 24 based on the sine signal SIN and the cosine signal COS stored in the storage device 32. Is calculated.

Further, the control device 30 drives the motor 10 until the rotation speed of the rotation shaft 11 of the motor 10 reaches a constant speed. When the rotation speed reaches a constant speed, the control of the motor 10 is released and the rotation shaft 11 is inertially rotated. In order to increase the moment of inertia of the rotating shaft 11 and stabilize the inertial rotation, in the correction mode, the rotating mass body 40 for generating the moment of inertia as shown in FIG. 1 may be fastened to the rotating shaft 11.

The control device 30 calculates the measurement angle θm according to the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 during the period of inertial rotation, and stores the measurement angle θm in the storage device 32.
Then, the control device 30 calculates the angle correction data Ca for correcting the measurement angle θm based on the measurement angle θm stored in the storage device 32.

An example of the functional configuration of the control device 30 will be described with reference to FIG. The control device 30 includes a detection signal correction unit 50, a rotation angle calculation unit 51, an angle correction unit 52, a drive signal generation unit 53, a data acquisition unit 54, and a correction value calculation unit 55.
The detection signal correction unit 50 corrects the sinusoidal signal SIN and the cosine signal COS based on the detection signal correction data Cs1 to Cs4 calculated in the correction mode. The detection signal correction data Cs1 to Cs4 are calculated by the correction value calculation unit 55 as described later.

See FIG. The detection signal correction unit 50 includes a SIN offset correction unit 60, a COS offset correction unit 61, a COS gain correction unit 62, an adder 63, a subtractor 64, and a phase error correction unit 65.
The SIN offset correction unit 60 and the COS offset correction unit 61 subtract the detection signal correction data Cs1 and Cs2 from the sine signal SIN and the cosine signal COS to obtain the offset error of the sine signal SIN and the cosine signal COS ((a) in FIG. 5). )) Is corrected.

The COS gain correction unit 62 corrects the amplitude error between the sinusoidal signal SIN and the cosine signal COS (see (b) in FIG. 5) by multiplying the cosine signal COS by the detection signal correction data Cs3.
The adder 63 calculates the sum signal (COS + SIN) of the sine signal SIN and the cosine signal COS, and the subtractor 64 calculates the difference signal (COS-SIN) between the sine signal SIN and the cosine signal COS.

The phase error correction unit 65 multiplies the difference signal (COS-SIN) by the detection signal correction data Cs4 to obtain the sine signal SIN and the cosine signal COS from the sum signal (COS + SIN) and the difference signal (COS-SIN). The effect of the phase error between them (see (c) in FIG. 5) is removed.
See FIG. The rotation angle calculation unit 51 measures the measurement angle θm (θm = 0) in an angle range in which the rotation axis 11 of the motor 10 rotates once from 0 degree to 360 degrees based on the sum signal (COS + SIN) and the difference signal (COS-SIN). Degree ~ 360 degrees) is calculated.

The angle correction unit 52 calculates and outputs the corrected measurement angle θc by correcting the measurement angle θm based on the angle correction data Ca calculated in the correction mode. The angle correction data Ca is calculated by the correction value calculation unit 55 as described later.
The angle correction data Ca will be described with reference to FIG. The solid line shows the measurement angle θm during one rotation of the rotation shaft 11 of the motor 10, and the alternate long and short dash line shows the desired calculation result (detection result) of the rotation angle. The correction value calculation unit 55 uses the difference between the desired calculation result θd and the measurement angle θm _i as the angle correction data Ca for _{each value θm i} of the measurement angle θm during one rotation of the rotation shaft 11 of the motor 10. calculate.

See FIG. The drive signal generation unit 53 generates a drive signal for controlling the drive circuit 35 based on the corrected measurement angle θc and the drive command Ref from the drive command generation unit 56 executed in the normal mode, and outputs the drive signal to the drive circuit 35. do. For example, the drive signal generation unit 53 outputs a gate signal for turning on / off the switching element mounted on the drive circuit 35.
As described above, in the normal mode, the control device 30 drives the motor 10 according to the rotation angle θ of the rotation shaft 11 of the motor 10.

On the other hand, when the control device 30 shifts to the correction mode, the data acquisition unit 54 controls the drive signal generation unit 53 to drive the motor 10 and rotate the rotation shaft 11.
Then, the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 while the motor 10 is rotating are stored in the storage device 32. In order to detect the offset error, amplitude error and phase error of the sine signal SIN and the cosine signal COS, the sine signal SIN and the cosine signal COS may be collected over a period of one rotation of the motor 10.

Further, the data acquisition unit 54 controls the drive signal generation unit 53 to drive the motor 10 until the rotation speed of the rotation shaft 11 of the motor 10 reaches a constant speed. When the rotation speed reaches a constant speed, the control of the motor 10 is released and the rotation shaft 11 is inertially rotated.
Then, the sum signal (COS + SIN) obtained by correcting the offset error, the amplitude error and the phase error of the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 during the period of inertial rotation by the detection signal correction unit 50. ) And the measurement angle θm calculated by the rotation angle calculation unit 51 based on the difference signal (COS-SIN), the storage device 32 stores the measurement angle θm.

The data collecting unit 54 collects the measurement angle θm over at least one rotation of the rotating shaft 11 in order to calculate the angle correction data Ca over one rotation of the rotating shaft 11 as shown in FIG.
Further, the data collection unit 54 may collect the measurement angle θm in the storage device 32 over a plurality of rotations of the rotation shaft 11. In this case, the data collection unit 54 calculates the rotation number nr of the rotation shaft 11 based on the change in the measurement angle θm, and accumulates the angles of one rotation or more of the rotation shaft 11 to obtain a continuous rotation angle (360). Degree x nr + measurement angle θm) may be stored in the storage device 32 as the measurement angle θm. Hereinafter, the continuous rotation angle (360 degrees × nr + measurement angle θm) obtained by accumulating the angles of one rotation or more of the rotation angle 11 may be referred to as the measurement angle θm in the multi-turn angle range.

The correction value calculation unit 55 calculates the detection signal correction data Cs1 to Cs4 based on the sinusoidal signal SIN and the cosine signal COS stored in the storage device 32. Further, the correction value calculation unit 55 calculates the angle correction data Ca based on the measurement angle θm stored in the storage device 32.
See FIG. 7. The correction value calculation unit 55 corrects the detection signal correction value calculation unit 70 and the angle correction value calculation unit 71.

The detection signal correction value calculation unit 70 calculates the offset error of the sine signal SIN and the cosine signal COS as the detection signal correction data Cs1 and Cs2 based on the sine signal SIN and the cosine signal COS stored in the storage device 32. For example, the average between n periods (n is a natural number) of the sinusoidal signal SIN and the cosine signal COS may be calculated as an offset error.
Further, the detection signal correction value calculation unit 70 calculates the ratio (As / Ac) of the amplitude As of the sinusoidal signal SIN and the amplitude Ac of the cosine signal COS as the detection signal correction data Cs3.
Further, the detection signal correction value calculation unit 70 calculates the ratio (Aa / Ad) of the amplitude Aa of the sum signal (COS + SIN) and the amplitude Ad of the difference signal (COS-SIN) as the detection signal correction data Cs4.

The angle correction value calculation unit 71 calculates the angle correction data Ca based on the measurement angle θm stored in the storage device 32.
An example of the measurement angle θm stored in the storage device 32 will be described with reference to (a) of FIG. 8 and (b) of FIG.

Now, it is assumed that the angle error shown in FIG. 8A is included in the measurement angle θm in the angle range from 0 degree to 360 degrees (that is, one rotation) of the rotation axis 11 of the motor 10. Further, it is assumed that the storage device 32 stores the measurement angle θm in the multi-turn angle range shown in FIG. 8 (b). The horizontal axis indicates the acquisition time (that is, the calculation time) of the measurement angle θm.
Since the measurement angle θm includes an angle error, the waveform of the measurement angle θm has pulsation as shown in FIG. 8B even if the rotation of the motor 10 is smooth.

See FIG. 7. The angle correction value calculation unit 71 includes an angular velocity calculation unit 72, a theoretical value calculation unit 73, and a linearity error calculation unit 74.
The angular velocity calculation unit 72 calculates the angular velocity ω of the rotation shaft 11 during the period of inertial rotation by the rotation shaft 11 based on the measurement angle θm stored in the storage device 32.
Refer to (b) of FIG. For example, the angular velocity calculation unit 72 may calculate the angular velocity ω1 of the head data unit of the measurement angle θm stored in the storage device 32 as the angular velocity ω during the inertial rotation period.

Further, for example, the angular velocity calculation unit 72 may calculate the average of the angular velocity ω1 of the head data unit and the angular velocity ω2 of the tail data unit stored in the storage device 32 as the angular velocity ω during the inertial rotation period.
For example, the angular velocity calculation unit 72 may set the average value of the angular velocities calculated based on the measurement angles θm acquired at a plurality of times in the head data unit as the angular velocity ω1, and the measurement angles acquired at the plurality of times in the tail data unit. The average value of the angular velocities calculated based on θm may be the angular velocity ω2. The length of the head data unit and the tail data unit may be, for example, one rotation cycle of the rotation shaft 11.

The theoretical value calculation unit 73 assumes that the rotating shaft 11 during the coasting rotation period moves at an equal angular velocity at an angular velocity ω (that is, assuming that the angular velocity of the rotating shaft 11 during the inertial rotation period is a constant angular velocity ω). ), The theoretical value θt of the rotation angle of the rotation axis 11 during the inertial rotation period is calculated.
Specifically, an ideal straight line showing a rotation angle that passes through the origin (time t = 0, rotation angle = 0) and changes at a constant angular velocity ω, as shown by the one-point chain line in FIG. Calculated as the theoretical value θt of the rotation angle inside.

See FIG. 7. The linearity error calculation unit 74 calculates the difference (θm−θt) between the measurement angle θm stored in the storage device 32 and the theoretical value θt as the angular linearity error θer.
Refer to (a) of FIG. The linearity error calculation unit 74 measures the angular linearity error θer, which is the difference (θm−θt) between the measurement angle θm and the theoretical value θt, over the angle range (0 degrees to 360 degrees) of one rotation of the measurement angle θm. And calculate.

Refer to (b) of FIG. When the measurement angle θm in the multi-turn angle range is stored in the storage device 32, the linearity error calculation unit 74 has the angular linearity for each of the time intervals T1, T2, ... Tn in which the measurement angle θm changes by 360 degrees. The errors θer1, θer2, ... θern may be calculated, and the average of these may be used as the angular linearity error θer.
The linearity error calculation unit 74 determines whether or not the calculated angular linearity error θer is within a predetermined allowable error range.

When the angle linearity error θer is within the permissible error range, the linearity error calculation unit 74 corrects the angle linearity error θer calculated for _{each value θm i} of the measurement angle θm with respect _{to the measurement angle θm i.} Store as data Ca. For example, the linearity error calculation unit 74 may store the angle correction data Ca in a predetermined storage area secured in the storage device 32. In the normal mode, the angle correction unit 52 reads the angle correction data Ca from the correction value calculation unit 55 and corrects the measurement angle θm.
When the angle linearity error θer is not within the permissible error range, the data acquisition unit 54 and the correction value calculation unit 55 coast the rotation axis 11 of the motor 10 again to redo the calculation of the angle correction data Ca.

At this time, the data acquisition unit 54 controls the drive signal generation unit 53 to drive the motor 10, and shifts to inertial rotation after the rotation speed of the rotation shaft 11 increases to some extent. In order to make it possible to more accurately determine the rotation speed at the time of shifting to inertial rotation, the angle correction data Ca calculated this time may be reflected in the driving of the motor 10 before shifting to inertial rotation. That is, the motor 10 may be driven by controlling the drive circuit 35 (for example, an inverter or the like) according to the rotation angle θc corrected by the angle correction data Ca calculated this time.

(motion)
Next, the operation of the control device 30 will be described.
In step S1, when the control device 30 enters the correction mode, the data acquisition unit 54 controls the drive signal generation unit 53 to drive the motor 10 and rotate the rotation shaft 11.
In step S2, the data acquisition unit 54 determines whether or not the rotation speed of the rotation shaft 11 is within a predetermined range. When the rotation speed is within the predetermined range (step S2: Y), the process proceeds to step S3. If the rotation speed is not within the predetermined range (step S2: N), the process returns to step S2.

In step S3, the data acquisition unit 54 stores the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 in the storage device 32. The correction value calculation unit 55 calculates the detection signal correction data Cs1 to Cs4 based on the sinusoidal signal SIN and the cosine signal COS stored in the storage device 32.
In step S4, the data acquisition unit 54 controls the drive signal generation unit 53 to drive the motor 10 until the rotation speed of the rotation shaft 11 of the motor 10 reaches a constant speed.

In step S5, the data acquisition unit 54 determines whether or not the rotation speed of the rotation shaft 11 is within a predetermined range. When the rotation speed is within the predetermined range (step S5: Y), the process proceeds to step S6. If the rotation speed is not within the predetermined range (step S5: N), the process returns to step S5.
In step S6, the data acquisition unit 54 releases the control of the motor 10 and coasts the rotating shaft 11.

In step S7, the data collection unit 54 stores the measurement angle θm calculated by the rotation angle calculation unit 51 in the storage device 32. The correction value calculation unit 55 calculates the angle correction data Ca based on the measurement angle θm stored in the storage device 32.
In step S8, the linearity error calculation unit 74 of the correction value calculation unit 55 determines whether or not the angle linearity error θer obtained during the calculation of the angle correction data Ca is within the permissible error range.

When the angular linearity error θer is within the permissible error range (step S8: Y), the process proceeds to step S10.
On the other hand, when the angle linearity error θer is not within the permissible error range (step S8: N), the calculation of the angle correction data Ca is repeated. In this case, in step S9, the angle correction data Ca calculated this time is reflected for driving the motor 10 in the subsequent step S4. After that, the process proceeds to step S4.
In step S10, the correction value calculation unit 55 stores the angle correction data Ca calculated this time for use by the angle correction unit 52 for correction of the measurement angle θm in the normal mode. After that, the process ends.

(Effect of the first embodiment)
(1) The rotation angle calculation device includes a sensor unit 20 that outputs a detection signal according to the rotation of the rotating body, a rotation angle calculation unit 51 that calculates the rotation angle of the rotating body based on the detection signal, and the rotating body coasting. The angular velocity calculation unit 72 and the angular velocity calculation unit 72 calculate the angular velocity of the rotating body based on the rotation angles calculated based on the detection signals output from the sensor unit 20 at a plurality of times during the period of rotation in. Based on the difference between the theoretical value calculation unit 73 that calculates the theoretical value of the rotation angle based on the calculated angular velocity, the rotation angle calculated by the rotation angle calculation unit 51, and the theoretical value calculated by the theoretical value calculation unit 73. It includes an angle correction unit 52 that corrects the rotation angle calculated by the rotation angle calculation unit 51.
Thereby, the linearity error of the rotation angle measured by the rotation angle calculation device can be corrected by a simple method without using an external measuring means.

(2) The theoretical value calculation unit 73 calculates the theoretical value of the rotation angle when the angular velocity of the rotating body is constant. As a result, a theoretical value that serves as a reference when correcting the rotation angle calculated by the rotation angle calculation unit 51 can be obtained by a simple method.

(Modification example)
The correction value calculation unit 55 of the first embodiment described above calculates the detection signal correction data Cs1 to Cs4 in the correction mode, but the present invention is not limited to such a form. The correction value calculation unit 55 of the modification may dynamically calculate the detection signal correction data Cs1 to Cs4 even in the normal mode.

FIG. 11 shows an example of the functional configuration of the control device 30 of the modified example. The data acquisition unit 54 collects the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 in the normal mode and the correction mode, and outputs them to the correction value calculation unit 55.
The correction value calculation unit 55 calculates the detection signal correction data Cs1 to Cs4 based on the sinusoidal signal SIN and the cosine signal COS while the motor 10 is rotating in the normal mode and the correction mode.
The detection signal correction unit 50 dynamically corrects the sinusoidal signal SIN and the cosine signal COS based on the detection signal correction data Cs1 to Cs4 calculated in the normal mode and the correction mode.

Further, the data collection unit 54 outputs the sinusoidal signal SIN and the cosine signal COS output by the MR sensor element 24 to the correction value calculation unit 55 when the measurement angle θm during coastal rotation in the correction mode is stored in the storage device 32. You may.
The correction value calculation unit 55 may dynamically calculate the detection signal correction data Cs1 to Cs4 while storing the measurement angle θm in the storage device 32 in the correction mode and the normal mode.
The data acquisition unit 54 stores in the storage device 32 the measurement angle θm calculated based on the sinusoidal signal SIN and the cosine signal COS corrected by the detection signal correction data Cs1 to Cs4 dynamically calculated by the correction value calculation unit 55. You can do it.

(Second Embodiment)
In the first embodiment, the theoretical value θt of the rotation angle is calculated on the assumption that the rotation axis 11 during the inertial rotation period moves at an angular velocity ω.
However, as shown in FIG. 12A, the actual angular velocity ω changes due to disturbance such as friction.

When the angular velocity ω changes, as shown in FIG. 12 (b), a dissociation occurs between the ideal theoretical value θt and the actual rotation angle. Therefore, when one rotation is performed, some angle error occurs in the theoretical value θt (see (c) in FIG. 12).
Therefore, in the second embodiment, the theoretical value θt of the rotation angle is calculated on the assumption that the rotation axis 11 during the inertial rotation period moves at an equal angular acceleration.
That is, the angular acceleration α of the rotating body is calculated based on the calculated value of the angular velocity ω at a plurality of times, and it is assumed that the angular acceleration of the rotating shaft 11 during the inertial rotation period is a constant value α, and the angular acceleration α is assumed to be a constant value α during the inertial rotation period. The theoretical value θt of the rotation angle of the rotation axis 11 is calculated.

Specifically, the theoretical value calculation unit 73 has an inertial rotation period based on the angular velocities ω1 and ω2 of the head data unit and the tail data unit shown in FIG. 8B and the time difference between the head data unit and the tail data unit. Calculate the angular acceleration α inside. Then, at the start time (time t = 0 seconds), the rotation angle is θ0 degrees, and the ideal curve of the quadratic function indicating the rotation angle that changes with the constant angular acceleration α is set as the theoretical value θt of the rotation angle during the inertial rotation period. Calculate as. Subsequent processing is the same as in the first embodiment.

(Effect of the second embodiment)
The theoretical value calculation unit 73 calculates the angular acceleration α of the rotating body based on the angular velocity ω calculated by the angular velocity calculation unit 72 at a plurality of times, and the theoretical value θt of the rotation angle when the angular acceleration α of the rotating body is constant. Is calculated.
As a result, even if the angular velocity ω changes due to a disturbance such as friction, the theoretical value θt of the rotation angle can be calculated accurately.

(Third Embodiment)
In the third embodiment, the angular velocity at each time is calculated, and the theoretical value of the rotation angle is calculated with higher accuracy by integrating these.
In the third embodiment, the data acquisition unit 54 (see FIG. 3) has a sampling timing t = 1, 2, ... k, k + 1, ... During the inertial rotation period of the rotating shaft 11, a measurement angle θm _(t) and a time. Information data T _(t) is acquired and stored in the storage device 32.

The angular velocity calculation unit 72 (see FIG. 7) sets the angular velocity ω _(k) at each of the sampling timings t = 1, 2, ..., The measurement angle θm _{(k), the} measurement angle θm _{(k + 1),} and the time information data T _(k). And the calculation is performed based on the time information data T _{(k + 1).} For example, the angular speed calculation unit 72 calculates the angular speed omega a _(k) based on the arithmetic expression _{ω (k) = (θm (} k + 1) -θm (k)) / (T (k + 1) -T (k)).

Angular velocity calculating section 72 averages the angular velocity omega _(k) the time over x-number of sampling timings before and after and calculates the angular velocity average value ω _{(k) Ave.}
The broken line in FIG. 13A shows an example of the angular velocity ω, and the solid line shows an example of the angular velocity average value ω _Ave of the angular velocity ω.

The theoretical value calculation unit 73 estimates the theoretical value of the rotation angle of the rotation axis 11 during the inertial rotation period by time-integrating the angular velocity ω or the angular velocity average value ω _Ave. The estimated theoretical value is expressed as "estimated angle θe".
For example, the theoretical value calculating section 73, the estimated angle θe at time _{T (k + 1)} of the _{(k + 1)} is calculated by the following arithmetic expression (1).
θe _{(k + 1)} = θe _(k) + ω _{(k) Ave} × (T _{(k + 1)} −T _(k) )… (1)

The theoretical value calculation unit 73, estimated angle θe at time _{T (k + 1)} of the _{(k + 1)} may be computed by the following arithmetic expression (2).
θe _{(k + 1)} = θe _(k) + ω _(k) × (T _{(k + 1)} −T _(k) )… (2)
_{The theoretical value calculation unit 73 obtains an estimated angle θe (k + 1)} at each of the sampling timings t = 1, 2, ..., And calculates the estimated angle θe during the inertial rotation period of the rotation axis 11.
The solid line in FIG. 13B shows an example of the measurement angle θm, and the broken line in FIG. 13B shows an example of the estimated angle θe.

The linearity error calculation unit 74 calculates the difference (θm−θe) between the measurement angle θm and the estimated angle θe as the angular linearity error θer.
See FIG. 14. The linearity error calculation unit 74 measures the angular linearity error θer, which is the difference (θm−θe) between the measurement angle θm and the estimated angle θe, over the angle range (0 degrees to 360 degrees) of one rotation of the measurement angle θm. And calculate.
Specifically, the angular linearity error θer _(t) = θm _(t) −θe _(t) between the measurement angle θm _(t) and the estimated angle θe _{(t) at} each sampling timing is calculated.

When the measurement angle θm in the multi-turn angle range is stored in the storage device 32 (see (b) in FIG. 9), the linearity error calculation unit 74 has a measurement angle θm of 360 as in the first embodiment. The angular linearity error θer1, θer2, ... θern may be calculated for each time interval T1, T2, ... Tn that changes in degree, and the average of these may be used as the angular linearity error θer.
See FIG. 14. The linearity error calculation unit 74 outputs the angle linearity error θer calculated for _{each value θm i} of the measurement angle θm as the angle correction data Ca for _{the measurement angle θm i.}

(motion)
An example of the calculation method of the angle linearity error θer in the third embodiment will be described with reference to FIG.
In step S10, the data collecting unit 54 acquires the _{measurement angle θm (t)} and the time information data T _(t) at the sampling timings t = 1, 2, ... k, k + 1, ... During the inertial rotation period of the rotating shaft 11. do.

In step S11, the angular velocity calculation unit 72 sets the angular velocity ω _(k) at each of the sampling timings t = 1, 2, ..., The measurement angle θm _{(k), the} measurement angle θm _{(k + 1)} , the time information data T _(k), and the time. The calculation is performed based on the information data T _{(k + 1).}
Angular velocity calculating unit 72 in step S12, the average angular speed omega _(k) time, and calculates the angular velocity average value ω _{(k) Ave.}

In step S13, the theoretical value calculation unit 73 calculates _{the estimated angle θe (k)} of the rotation angle of the rotation axis 11 during the inertial rotation period by time-integrating the _{angular velocity average value ω (k) Ave.}
In step S14, the linearity error calculation unit 74 calculates _{the difference between the measurement angle θm (k)} and the estimated angle θe _(k) as the angular linearity error θer.

(Effect of the third embodiment)
(1) The theoretical value calculation unit 73 integrates the angular velocity ω calculated by the angular velocity calculation unit 72 to calculate the estimated angle θe, which is the theoretical value of the rotation angle. As a result, the angular linearity error θer can be calculated accurately according to the change in the angular velocity ω generated during the inertial rotation period.
(2) The angular velocity calculation unit 72 calculates the time average value ω _Ave of the angular velocity ω, and the theoretical value calculation unit 73 _{integrates the time average value ω Ave} to calculate the estimated angle θe. This makes it possible to accurately calculate the estimated angle θe by suppressing the influence of noise.

(Application of rotation angle arithmetic unit)
Next, with reference to FIG. 16, a configuration example will be described when the rotation angle calculation device of the present embodiment is applied to an electric power steering device that controls a steering assist force applied to the steering system of the vehicle.
The column shaft 102 of the steering handle 101 is connected to the tie rod 106 of the steering wheel via the reduction gear 103, the universal joints 104A and 104B, and the pinion rack mechanism 105. The column shaft 102 is provided with a torque sensor 110 that detects the steering torque Th of the steering handle 101, and a motor 10 that assists the steering force of the steering handle 101 is connected to the column shaft 102 via the reduction gear 103. Has been done.

The control device 30 described above is used as an electronic control unit that controls the power steering device. Power is supplied to the control device 30 from the battery 114, which is a power source, and an ignition key signal is input from the ignition key 111.
The control device 30 calculates the steering angle θh of the steering handle 101 based on the rotation angle θc of the motor 10 calculated as described above and the reduction ratio N of the reduction gear 103. The control device 30 calculates the steering assist command value of the assist command using the assist map or the like based on the steering angle θh, the steering torque Th, and the vehicle speed Vh detected by the vehicle speed sensor 112, and is calculated. The current I supplied to the motor 10 is controlled based on the steering assist command value.

In the electric power steering device having such a configuration, the torque sensor 110 detects the steering torque Th by the driver's handle operation transmitted from the steering handle 101, and calculates the steering angle θh based on the rotation angle θc of the motor 10. Then, the motor 10 is driven and controlled by the steering assist command value calculated based on the steering torque Th, the steering angle θh, and the vehicle speed Vh, and this drive is applied to the steering system as an assist force (steering assist force) for the driver's steering wheel operation. Granted.

10 ... motor, 11 ... rotating shaft, 12 ... output end, 14 ... end, 20 ... sensor unit, 21 ... magnet, 22 ... circuit board, 23 ... support member, 24 ... MR sensor element, 25 ... harness, 30 ... Control device, 31 ... Processor, 32 ... Storage device, 33, 34 ... Analog digital converter, 35 ... Drive circuit, 40 ... Rotation mass body, 50 ... Detection signal correction unit, 51 ... Rotation angle calculation unit, 52 ... Angle correction Unit, 53 ... Drive signal generation unit, 54 ... Data collection unit, 55 ... Correction value calculation unit, 60 ... SIN offset correction unit, 61 ... COS offset correction unit, 62 ... COS gain correction unit, 63 ... Adder, 64 ... Subtractor, 65 ... Phase error correction unit, 70 ... Detection signal correction value calculation unit, 71 ... Angle correction value calculation unit, 72 ... Angle speed calculation unit, 73 ... Theoretical value calculation unit, 74 ... Linear error calculation unit, 101 ... Steering handle, 102 ... Column shaft, 103 ... Reduction gear, 104A, 104B ... Universal joint, 105 ... Pinion rack mechanism, 106 ... Tie rod, 110 ... Torque sensor, 111 ... Ignition key, 112 ... Vehicle speed sensor, 114 ... Battery

Claims (10)

It is a correction method of a rotation angle calculation device that calculates the rotation angle of the rotating body based on the detection signal output from the sensor according to the rotation of the rotating body.
The rotation angle is calculated based on the detection signal output from the sensor at a plurality of times during the period in which the rotating body is inertially rotating.
Based on the calculated rotation angle, the angular velocity of the rotating body is calculated.
Based on the calculated angular velocity, the theoretical value of the rotation angle is calculated.
The rotation angle calculated based on the detection signal is corrected based on the difference between the rotation angle calculated based on the detection signal and the theoretical value.
A correction method for a rotation angle arithmetic unit. The correction method according to claim 1, wherein the theoretical value of the rotation angle is calculated when the angular velocity of the rotating body is constant. The angular acceleration of the rotating body is calculated based on the calculated values of the angular velocities at a plurality of times.
The theoretical value of the rotation angle when the angular acceleration of the rotating body is constant is calculated.
The amendment method according to claim 1, wherein the amendment method is characterized by the above. Integrate the angular velocity to calculate the theoretical value of the rotation angle.
The amendment method according to claim 1, wherein the amendment method is characterized by the above. Calculate the time average value of the calculated angular velocity,
The theoretical value of the rotation angle is calculated by integrating the calculated time average value.
The amendment method according to claim 4, wherein the amendment method is characterized by the above. A sensor that outputs a detection signal according to the rotation of the rotating body,
A rotation angle calculation unit that calculates the rotation angle of the rotating body based on the detection signal,
An angular velocity calculation unit that calculates the angular velocity of the rotating body based on the rotation angle calculated based on the detection signal output from the sensor at a plurality of times during the period in which the rotating body is rotating by inertia. A theoretical value calculation unit that calculates the theoretical value of the rotation angle based on the angular velocity calculated by the angular velocity calculation unit.
An angle correction unit that corrects the rotation angle calculated by the rotation angle calculation unit based on the difference between the rotation angle calculated by the rotation angle calculation unit and the theoretical value calculated by the theoretical value calculation unit.
A rotation angle arithmetic unit characterized by being provided with. A storage unit that stores the difference between the rotation angle calculated by the rotation angle calculation unit and the theoretical value calculated by the theoretical value calculation unit as a correction value for correcting the rotation angle calculated by the rotation angle calculation unit. The rotation angle calculation device according to claim 6, further comprising. The rotation angle calculation device according to claim 6 or 7, which calculates the rotation angle of the rotation axis of the motor as the rotating body.
A drive unit that drives the motor according to the rotation angle corrected by the angle correction unit, and a drive unit.
A motor control device characterized by being provided with. The motor control device according to claim 8 and
The motor controlled by the motor control device and
An electric actuator product characterized by being equipped with. The motor control device according to claim 8 and
The motor controlled by the motor control device and
An electric power steering device comprising the above, wherein a steering assist force is applied to a steering system of a vehicle by the motor.

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