JP2006029937A - Compensation method for rotation angle of rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compensation method for angle of rotation of an angle of rotation detector with high precision in which mechanical error of gears and electric error of an absolute angle of rotation detector are compensated with fewer compensation angle data. <P>SOLUTION: In the angle of rotation detector for steering of multiple rotation used for a car body control system of a car, a motor 15 for rotating a rotary shaft to be tested 7, a motor controller 14 for controlling the absolute angle of rotation of the motor 15 and an encoder 16 for detecting the absolute angle of rotation of the motor 15 are combined. The difference between the absolute angle of rotation of the rotary shaft to be tested 7 actually rotated by the motor 15 and a calculated absolute angle of rotation at every specific interval of the rotary shaft to be tested 7 obtained from absolute angle of rotation detectors 4 and 5 of a second and a third gears 2 and 3 is stored in a non-volatile memory 11 as a compensation angle. In the specific calculated absolute angles of rotation, the calculated absolute angle of rotation of the rotary shaft to be teste 7 is compensated with the difference between a straight line of the calculated absolute angle of rotation obtained using the compensation angle for the before and after the calculated absolute angle of rotation and a straight line of an ideal absolute angle of rotation not including a rotation detection error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle correction method for a rotation angle detection device for a multi-turn steering wheel used in a vehicle body control system of an automobile.

  Conventionally, as an apparatus for detecting the absolute rotation angle of a rotating body that rotates multiple times, such as an absolute encoder, a rotation angle that detects the absolute rotation angle of a rotating shaft to be detected from the absolute rotation angles of a plurality of rotating bodies having phase differences. Measurement methods and devices exist.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 63-118614 A

  However, the above-described apparatus has a problem that the detection accuracy of the absolute rotation angle of the rotation shaft to be detected is deteriorated due to the alignment accuracy of the gears, the center deflection, and the detection error in the absolute rotation angle detection unit.

  The present invention is for solving this problem, and an object of the present invention is to provide a highly accurate rotation angle correction method for a rotation angle detector that corrects mechanical errors of gears and electrical errors of an absolute rotation angle detector. It is what.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, the second and third gears, which are sequentially engaged with the first gear fitted to the rotation shaft to be tested and have different numbers of teeth, respectively, An absolute rotation angle detecting unit for detecting the absolute rotation angle of each gear, and based on the detected combination of the absolute rotation angles of the second and third gears, the absolute rotation in multiple rotations of the rotation shaft to be tested In the rotation angle detection device for detecting an angle, a motor for rotating the rotation shaft to be tested, a motor controller for controlling the absolute rotation angle of the motor, and an encoder for detecting the absolute rotation angle of the motor, An absolute rotation angle of the test rotation shaft actually rotated by a motor and a calculated absolute rotation angle for each predetermined interval of the test rotation shaft obtained from the absolute rotation angle detection unit of the second and third gears. Non-volatile with difference as correction angle The difference between the calculated absolute rotation angle line calculated from the correction angle for the calculated absolute rotation angle before and after the predetermined absolute rotation angle and the ideal absolute rotation angle line not including the rotation detection error is stored between the predetermined calculated absolute rotation angles. The calculated absolute rotation angle of the test rotation shaft is corrected.

  The invention according to claim 2 of the present invention stores the hysteresis angle calculated by rotating the test rotation shaft in the reverse direction after rotating the test rotation shaft in one direction, and storing the hysteresis angle in the nonvolatile memory, The calculated absolute rotation angle is corrected by this hysteresis angle every time the rotation axis of the test rotates in the reverse direction.

  According to a third aspect of the present invention, the correction angle calculated over the necessary detection range of the test rotation axis is stored in a nonvolatile memory, and the calculated absolute rotation angle of the test rotation axis is corrected.

  According to a fourth aspect of the present invention, the correction angle calculated over one cycle of the first gear fitted to the test rotation shaft is stored in the nonvolatile memory, and the calculated absolute rotation angle of the test rotation shaft is stored. It is to correct.

  The invention according to claim 5 of the present invention is calculated over one cycle of any one of the second gear and the third gear sequentially engaged with the first gear fitted to the test rotating shaft. The corrected angle is stored in a nonvolatile memory, and the calculated absolute rotation angle of the rotation axis to be detected is corrected.

  According to these inventions, by using a small amount of correction angle data and storing it in a nonvolatile memory with a smaller capacity, it is possible to detect a mechanical rotation angle detection error of the gear and an electrical rotation angle of the absolute rotation angle detection unit. The detection error can be corrected with a simple configuration, and the effect of greatly improving the detection accuracy of the absolute rotation angle calculated by the rotation axis to be detected can be obtained.

  According to the present invention, the absolute rotation angle detection error caused by the mechanical error of the gear and the electrical error of the absolute rotation angle detection unit is corrected with a correction angle obtained in advance with a nonvolatile memory having a smaller capacity. Thus, the rotation angle correction method of the rotation angle detection device that detects the multiple rotations of the rotation shaft to be detected with high accuracy can be provided in a simple form.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9 and (Table 1).

  1A and 1B are a front view and a side view showing a configuration of a rotation angle detection device according to an embodiment of the present invention, and FIG. 2 is an absolute rotation angle detection of the second and third gears shown in FIG. FIG. 3 is a system configuration diagram of the rotation angle correction method of the rotation angle detector, and FIG. 4 is a multiple rotation of the first gear 1 based on the absolute rotation angles of the second gear 2 and the third gear 3. FIG. 5 is a diagram showing the principle of correction of linearity, FIG. 6 is a diagram showing the principle of correction of hysteresis, and FIGS. 7 to 9 are errors included in the calculated absolute rotation angle and the test. It is a figure which shows the relationship with the absolute rotation angle of the rotating shaft. Table 1 shows a specific method for correcting linearity.

  FIGS. 1A and 1B show the configuration of a rotation angle detection device 6 that detects multiple rotations of the rotation shaft 7 to be tested. The first gear 1 is fitted to the test rotating shaft 7, the second gear 2 is engaged with the first gear 1, and the third gear 3 is sequentially engaged with the second gear 2. A first magnet 8 and a second magnet 9 are disposed in the central portions of the second gear 2 and the third gear 3, respectively.

  In FIG. 2, a first absolute rotation angle detection unit 4 that detects an absolute rotation angle at a position that faces the first magnet 8 and a first rotation angle that detects an absolute rotation angle at a position that faces the second magnet 9. Two absolute rotation angle detectors 5 are arranged. The first and second absolute rotation angle detectors 4 and 5 are respectively arranged on the printed circuit board 10, and the first absolute rotation angle detector 4 is fixed to the center of the second gear 2. The second absolute rotation angle detection unit 5 detects the magnetic field direction of the second magnet 9 fixed to the center of the third gear 3.

  In FIG. 3, a non-volatile memory (EEPROM) 11 is for storing correction angles and the like. The CPU 12 is connected to the nonvolatile memory (EEPROM) 11 and the first and second absolute rotation angle detectors 4 and 5 and calculates the absolute rotation angle. The CPU 12 and the motor controller 14 are connected by a serial communication line 13 that transmits and receives an angle signal and a command signal so that signals can be transmitted and received. A motor 15 is attached to the rotating shaft 7 to be tested, and the motor controller 14 drives and controls the rotation with high accuracy. The absolute rotation angle of the rotation shaft 7 to be detected is detected with high accuracy by the encoder 16 and is transmitted to the motor controller 14.

  Next, a method for detecting the absolute rotation angle of the test rotating shaft 7 will be described.

  In FIG. 1, when the test rotating shaft 7 rotates, the first gear 1 fitted to the test rotating shaft 7 rotates. When the first gear 1 is rotated, the second gear 2 engaged with the first gear 1 and the third gear 3 engaged with the second gear 2 are rotated in conjunction with the rotation. Since the second gear 2 and the third gear 3 have different numbers of teeth, the second gear 2 and the third gear 3 rotate at different speeds with respect to the rotation shaft 7 to be tested. A signal for calculating the absolute rotation angle of the second gear 2 is output from the first absolute rotation angle detection unit 4, and similarly, an absolute rotation angle of the third gear 3 is output from the second absolute rotation angle detection unit 5. A signal for calculating is obtained.

  A method for calculating the absolute rotation angle of the test rotating shaft 7 in multiple rotations will be described with reference to FIG. In the upper part of FIG. 4, when the number of teeth of the first gear 1 is a, the number of teeth of the second gear 2 is b, and the number of teeth of the third gear 3 is c, the second gear 2 is rotated under test. The first gear 1 fitted on the shaft 7 rotates at a gear ratio (a / b) with respect to the rotation of the first gear 1, and the third gear 3 is fitted on the rotation shaft 7 to be tested. The gear rotates at the speed of the gear ratio (a / c) with respect to the rotation of the first gear 1, but since b ≠ c, the phase difference between the absolute rotation angles of the second gear 2 and the third gear 3. Fluctuates with a certain regularity. 4, the difference between the absolute rotation angle value 17 of the second gear 2 and the absolute rotation angle value 18 of the third gear 3 is rotated with respect to the absolute rotation angle 19 in the multiple rotation of the rotation shaft 7 to be tested. It shows that it is determined on a straight line in the detection range and one-to-one.

  Next, a correction method for improving the detection accuracy of the absolute rotation angle of the test rotating shaft 7 will be described.

  In the lower part of FIG. 4, an ideal absolute rotation angle 20 (hereinafter referred to as an ideal absolute angle) 20 of the test rotation shaft 7 is on a straight line shown here with respect to the absolute rotation angle 19 of the test rotation shaft 7 in multiple rotations. The absolute rotation angle (hereinafter referred to as a calculated absolute angle) 21 calculated from the signals of the first absolute rotation angle detection unit 4 and the second absolute rotation angle detection unit 5 is the first gear 1 and the second gear. Mechanical detection errors such as tooth arrangement accuracy of the gear 2 and center runout, and electrical detection errors in the first absolute rotation angle detection unit 4 and the second absolute rotation angle detection unit 5 are included. This does not coincide with the ideal absolute angle 20 of the rotation axis 7 to be examined. Therefore, the difference between the calculated absolute angle 21 and the ideal absolute angle 20 is stored in the nonvolatile memory (EEPROM) 11 as a correction angle with respect to the absolute rotation angle 19 of the rotation shaft 7 to be tested, and the calculated absolute angle 21 is calculated with this correction angle. By correcting it, the detection accuracy of the absolute rotation angle of the rotation shaft 7 to be detected can be raised close to the ideal absolute angle 20.

  With reference to FIGS. 5 to 9 and (Table 1), the detection accuracy of the absolute rotation angle of the rotation shaft 7 to be detected, particularly the method for correcting the linearity will be described in more detail.

  In FIG. 5, the horizontal axis represents the absolute rotation angle of the test rotation shaft 7 calculated by the rotation angle detection device 6, and the vertical axis represents the absolute rotation angle obtained by actually rotating the test rotation shaft 7. The motor 15 is controlled by the motor controller 14 so that the calculated absolute angle transmitted from the serial communication line 13 changes every 1 °. The absolute rotation angle of the rotation shaft 7 to be detected at that time is detected by the encoder 16. The correction angle for the calculated absolute angle every 1 ° is obtained by the following equation.

(Correction angle for calculated absolute angle every 1 °) = (Absolute rotational angle of rotation shaft 7 to be measured) − (Absolute calculated angle every 1 °) (1)
Since the correction angle for the calculated absolute angle smaller than 1 ° (for example, the calculated absolute angle every 0.1 °) is not stored in the nonvolatile memory (EEPROM) 11, the correction angle for every 0.1 ° is smaller than the correction angle for every 1 °. Estimate the calculated absolute angle. Let x be the calculated absolute angle every 0.1 °, and c be the closest calculated absolute angle every 1 ° smaller than x. That is, c <x <c + 1. When m is a correction angle in (c + 1), n is a correction angle in c, and the calculated absolute angle of the rotation shaft 7 to be linearly approximated based on these correction angles, the calculated absolute angle Y1 is expressed by the following equation.

Y1 = (m−n + 1) · (x−c) + n (2)
Since the ideal calculated absolute angle can be defined as being coincident with the actual absolute rotation angle of the rotation axis 7 to be examined, assuming that the ideal calculated absolute angle is Y2, Y2 = x−c (3)
It is expressed. That is, the difference between Y1 and Y2 is the correction angle. This can be obtained as follows from equations (2) and (3).

Y1-Y2 = (mn). (Xc) + n (4)
(Table 1) shows a method of calculating the correction angle every 0.1 ° from the correction angle every 1 ° using the equation (4). When the calculated absolute angle of the rotation angle detection device 6 is 0 ° at the initial setting, the absolute rotation angle of the rotation shaft 7 to be detected is also 0 °. First, the motor 15 is rotated by the motor controller 14 and the serial communication line 13 is monitored. When the calculated absolute angle becomes 1 °, the absolute rotation angle of the rotating shaft 7 to be detected is determined by the encoder 16. In this (Table 1), it is 0.8 °. That is, the correction angle with respect to the calculated absolute angle 1 ° of the rotation angle detection device 6 is −0.2 ° from the equation (1). From these correction angles every 1 °, correction angles every 0.1 ° in the range of 0 ° to 1 ° are obtained from the equation (4). Since m is a correction angle at (c + 1), that is, a calculated absolute angle of 1 °, it is −0.2 °. On the other hand, since n is a correction angle at c, that is, a correction angle at 0 °, it is 0 °. The equation for calculating the correction angle every 0.1 ° from 0 ° to 1 ° is obtained by substituting these values into the equation (4). Y1−Y2 = (− 0.2−0) · (x−0) +0
= −0.2 · x (5)
It becomes. For example, the correction angle when the calculated absolute angle x is 0.1 ° is −0.02 ° from the equation (5). This assumes that even if the calculated absolute angle is 0.1 °, the rotation axis 7 to be tested will only rotate 0.08 ° (0.1-0.02). When the calculated absolute angle x is 0.5 °, the correction angle is −0.1 ° from the equation (5), and the calculated absolute angle 0.5 ° is 0.4 ° (0.5−0.1). Will be corrected.

  Subsequently, the motor 15 is rotated by the motor controller 14 until the calculated absolute angle of the rotation angle detection device 6 becomes 2 °. The absolute rotation angle of the rotation shaft 7 to be detected at this time is detected by the encoder 16. In Table 1, it is 2.2 °. That is, the correction angle for the calculated absolute angle of 2 ° is + 0.2 ° from the equation (1). From these correction angles every 1 °, correction angles every 0.1 ° in the range of 1 ° to 2 ° are obtained from the equation (4) as follows.

Since m is a correction angle at (c + 1), that is, the calculated absolute angle 2 ° of the rotation angle detection device 6, it is + 0.2 °. On the other hand, since n is a correction angle at c, that is, a correction angle at 1 °, it is −0.2 °. The equation for obtaining the correction angle every 0.1 ° from 1 ° to 2 ° is obtained by substituting these values into the equation (4). Y1-Y2 = (0.2 − (− 0.2) · (x -1) -0.2
= 0.4 · (x−1) −0.2 (6)
It becomes. For example, the correction angle when the calculated absolute angle x is 1.1 ° is −0.16 ° from the equation (6). This assumes that even if the calculated absolute angle is 1.1 °, the rotation axis 7 to be tested will only rotate 0.94 ° (1.1-0.16). When the calculated absolute angle x is 1.5 °, the correction angle is 0 ° from the equation (6), and the calculated absolute angle 1.5 ° is estimated to be on the straight line of the ideal absolute angle without correction. ing.

  Next, the motor 15 is rotated by the motor controller 14 until the calculated absolute angle of the rotation angle detection device 6 becomes 3 °. The absolute rotation angle of the rotation shaft 7 to be detected at this time is similarly detected by the encoder 16. In Table 1, it is 3.2 °. In other words, the correction angle for the calculated absolute angle of 3 ° is + 0.2 ° from the equation (1). From these correction angles every 1 °, correction angles every 0.1 ° in 2 ° to 3 ° are obtained from the equation (4) as follows.

Since m is a correction angle at (c + 1), that is, a calculated absolute angle of 3 °, it is + 0.2 °. On the other hand, since n is a correction angle at c, that is, a correction angle at 2 °, it is + 0.2 °. The equation for obtaining the correction angle every 0.1 ° from 2 ° to 3 ° is obtained by substituting these values into the equation (4). Y1−Y2 = (0.2−0.2) · (x−2) ) +0.2
= 0.2 ... (7)
It becomes. For example, the correction angle when the calculated absolute angle x is 2.1 ° is 0.2 ° from the equation (7). This estimates that even if the calculated absolute angle is 2.1 °, the rotation axis 7 to be tested will rotate 2.3 ° (2.1 + 0.2). Also, the correction angle when the calculated absolute angle x is 2.5 ° is 0.2 ° from the equation (7), and the calculated absolute angle 2.5 ° is corrected to 2.7 ° (2.5 + 0.2). .

  Next, the detection accuracy of the absolute rotation angle of the rotation shaft 7 to be tested, particularly the method for correcting the hysteresis will be described with reference to FIG.

  In FIG. 6, the horizontal axis represents the absolute rotation angle calculated by the rotation angle detection device 6, and the vertical axis represents the absolute rotation angle of the test rotation shaft 7. The motor 15 is rotated while the calculated absolute angle transmitted from the serial communication line 13 is monitored by the motor controller 14. First, the motor 15 is rotated in the direction in which the calculated absolute angle increases. Next, the motor 15 is rotated in the reverse direction. At this time, the absolute rotation angle of the rotation shaft 7 to be tested until the calculated absolute angle fluctuates is obtained from the encoder 16. This value is stored in the nonvolatile memory (EEPROM) 11 as a hysteresis correction angle. As a factor of this hysteresis, backlash of a gear or the like can be considered, and this correction angle varies depending on the rotational position of the rotation shaft 7 to be tested. Therefore, the average value of hysteresis at a plurality of rotational positions may be used as the correction angle.

  In the rotation angle detection device 6, when the calculated absolute angle decreases, the correction angle of this hysteresis is added to the calculated absolute angle to correct a decrease in accuracy due to the hysteresis. Next, when the rotation axis 7 to be tested is inverted and the calculated absolute angle increases, the hysteresis is not corrected.

  Next, a method for further reducing the capacity of the nonvolatile memory (EEPROM) 11 storing the linearity correction angle for correcting the error included in the calculated absolute angle will be described with reference to FIGS.

  In the graphs shown in the lower part of FIGS. 7 to 9, the horizontal axis represents the absolute rotation angle of the rotation shaft 7 to be tested, and the vertical axis represents the error of the calculated absolute angle 21 of the rotation angle detection device 6. When the calculated absolute angle 21 coincides with the ideal absolute angle 20 as shown in the middle stage of FIGS. 7 to 9, the error of the calculated absolute angle 21 shown in the lower stage becomes zero, and a highly accurate rotation angle detection device can be realized. It is shown that. In FIG. 7, since there is no correlation between the absolute rotation angle of the test rotating shaft 7 and the error of the calculated absolute angle 21, all the correction angles of linearity in the detection range are stored in the nonvolatile memory (EEPROM) 11 and calculated. The absolute angle 21 needs to be close to the ideal absolute angle 20. Therefore, a large-capacity nonvolatile memory (EEPROM) 11 is required. On the other hand, in FIG. 8, the error curve of the calculated absolute angle has a cycle of the absolute rotation angle 360 ° of the rotation axis 7 to be tested. This indicates that the error of the calculated absolute rotation angle is dominant due to the first gear 1 shown in FIG. In this case, unlike the case of FIG. 7, only the linearity correction angle in the range of the absolute rotation angle 0 to 360 ° of the rotation shaft 7 to be tested is stored in the nonvolatile memory (EEPROM) 11, so that the calculated absolute angle 21 is ideal. The absolute angle 20 can be approached. Therefore, the error of the calculated absolute angle can be reduced with less nonvolatile memory (EEPROM) 11 than in the case of FIG.

  On the other hand, in FIG. 9, the calculated absolute angle error curve has the rotation period of the second gear 2. This indicates that the error of the calculated absolute angle is dominant due to the second gear 2 shown in FIG. In this case, unlike FIGS. 7 and 8, if the number of teeth of the first gear 1 is a and the number of teeth of the second gear 2 is b (here, a> b), the rotation shaft to be tested The calculated absolute angle can be brought close to the ideal absolute angle 20 by storing only the linearity correction angle in the range of 0 to 360 · b / a ° of the absolute rotation angle 7 in the nonvolatile memory (EEPROM) 11. Therefore, the error of the calculated absolute angle can be reduced with less nonvolatile memory (EEPROM) 11 than in the case of FIG.

  As described above, in the rotation angle correction method of the rotation angle detection device 6 in the present embodiment, over the range where the first gear 1 in the entire detection range rotates once or over the range where the second gear 2 rotates once. By storing a correction angle for the calculated absolute angle of the rotation axis 7 to be tested in a nonvolatile memory (EEPROM) 11, a detection error of the absolute rotation angle due to a mechanical error of the gear and an electrical error of the absolute rotation angle detector is also obtained. The operational effect is obtained that it can be corrected and the accuracy of the calculated absolute angle of the rotation axis to be tested can be improved. In addition, since the correction angle is stored at every certain absolute rotation angle, there is an effect that the detection accuracy of the rotation axis 7 to be detected can be increased with the nonvolatile memory 11 having a smaller capacity.

  The rotation angle correction method of the rotation angle detection device according to the present invention has the effect of being able to detect multiple rotations of the rotation axis to be detected with high accuracy with a simple configuration using a nonvolatile memory with a smaller capacity. It is suitable for use as a rotation angle correction method of a rotation angle detection device used for power steering of a vehicle.

(A) The front view which shows the structure of the rotation angle detection apparatus in embodiment of this invention, (b) The side view The enlarged view of the absolute rotation angle detection part of the 2nd and 3rd gearwheel shown in FIG. System configuration diagram of the rotation angle correction method of the rotation angle detector Principle diagram for calculating the absolute rotation angle of the first gear 1 in multiple rotations from the absolute rotation angles of the second gear 2 and the third gear 3 Principle diagram showing how to correct linearity Principle diagram showing how to correct hysteresis The figure which shows the relationship between the error contained in a calculation absolute angle, and the absolute rotation angle of the rotating shaft 7 to be tested. The figure which shows the relationship between the error contained in a calculation absolute angle, and the absolute rotation angle of the rotating shaft 7 to be tested. The figure which shows the relationship between the error contained in a calculation absolute angle, and the absolute rotation angle of the rotating shaft 7 to be tested.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st gear 2 2nd gear 3 3rd gear 4 1st absolute rotation angle detection part 5 2nd absolute rotation angle detection part 6 Rotation angle detection apparatus 7 Rotating shaft 8 to be tested 8 1st magnet 9 1st Magnet of 2 10 Printed circuit board 11 Non-volatile memory (EEPROM)
12 CPU
13 Serial communication line 14 Motor controller 15 Motor 16 Encoder 17 Absolute rotation angle value of gear 2 18 Absolute rotation angle value of gear 3 19 Absolute rotation angle of rotation shaft 7 to be tested 20 Straight line of ideal absolute angle of rotation shaft 7 to be tested 21 Calculated absolute angle 22 of the test rotary shaft 22 Straight line of ideal absolute angle of the test rotary shaft 23 Straight line of calculated absolute angle 24 of the test rotary shaft 7 calculated from the correction angle 24, 25, 26 Error curve of the calculated absolute angle

Claims (5)

Second and third gears that are sequentially engaged with the first gear fitted to the rotation shaft to be tested and have different numbers of teeth, and absolute rotation angles that detect the absolute rotation angles of the second and third gears, respectively. A rotation angle detecting device for detecting an absolute rotation angle in multiple rotations of the rotation shaft to be detected based on a combination of the detected absolute rotation angles of the second and third gears. Using the motor that rotates the test rotation shaft, the motor controller that controls the absolute rotation angle of the motor, and the encoder that detects the absolute rotation angle of the motor, the test rotation shaft that is actually rotated by the motor And the difference between the absolute rotation angle of the second and third gears calculated from the absolute rotation angle detection unit of the second and third gears at a predetermined interval of the rotation axis to be tested is stored in a nonvolatile memory as a correction angle, The predetermined calculation limit Between the rotation angles, the calculated absolute rotation angle of the rotation axis to be tested is the difference between the calculated absolute rotation angle straight line calculated from the correction angle for the calculated absolute rotation angle before and after that and the ideal absolute rotation angle straight line not including the rotation detection error. A rotation angle correction method for a rotation angle detection device that corrects the rotation angle. After rotating the test rotation shaft in one direction, the hysteresis angle calculated by rotating the test rotation shaft in the reverse direction is stored in the nonvolatile memory, and the calculation is performed every time the test rotation shaft rotates in the reverse direction. The rotation angle correction method of the rotation angle detection device according to claim 1, wherein the absolute rotation angle is corrected by the hysteresis angle. The rotation angle correction method of the rotation angle detection device according to claim 1, wherein the correction angle calculated over a necessary detection range of the rotation axis to be detected is stored in a nonvolatile memory. The rotation angle correction method of the rotation angle detection device according to claim 1, wherein the correction angle calculated over one cycle of the first gear fitted to the rotation shaft to be tested is stored in the nonvolatile memory. The correction angle calculated over one cycle of any one of the second and third gears sequentially engaged with the first gear fitted to the test rotating shaft is stored in the nonvolatile memory. The rotation angle correction method for the rotation angle detection device according to claim 1.

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