Rotation measurement system, rotation sensor calibration system, and rotation measurement method

Abstract

To detect angular acceleration from tangential acceleration without needing a distance to an acceleration detection point.SOLUTION: A rotor shaft 11 has: a second shaft part 112; and a third shaft part 113 that has a radial difference rd between the second shaft part 112 and the third shaft part. A rotor measuring system is configured to: arrange, in a position line symmetric with respect to a rotor center shaft C on an outer peripheral surface of the second shaft part 112, an acceleration sensor A1 and acceleration sensor B1 detecting acceleration in a tangential direction; arrange, in a position line symmetric with respect to the rotor center shaft C on an outer peripheral surface of the third shaft part 113, an acceleration sensor A2 and acceleration sensor B2 detecting acceleration in the tangential direction; and calculate angular acceleration from tangential acceleration obtained from the acceleration detected by the acceleration sensor A1 and acceleration sensor B1, tangential acceleration obtained from the acceleration detected by the acceleration sensor A2 and acceleration sensor B2, and the radial difference rd.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention mainly relates to a rotation measurement system that measures angular acceleration and calibration of a rotation sensor using the rotation measurement system. [Background technology]

[0002] A known technique for detecting angular acceleration is to detect tangential acceleration using two acceleration sensors positioned symmetrically about the central axis of rotation, and calculate angular acceleration from the detected tangential acceleration by utilizing the fact that tangential acceleration is proportional to angular acceleration (for example, Patent Documents 1 and 2).

[0003] Furthermore, a known technique for calibrating a rotation sensor involves rotating an examination table equipped with a rotation sensor that detects angular velocity by a reference angle, and calibrating the rotation sensor from the difference between the integrated value of the angular velocity detected by the rotation sensor for that rotation and the reference angle (for example, Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-79885 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-116274 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-139561 [Patent Document 4] Japanese Patent Application Publication No. 6-331365 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technique for calculating angular acceleration from tangential acceleration detected using the acceleration sensor described above, the tangential acceleration is also proportional to the distance from the central axis of rotation of the rotating body. Therefore, unless the exact distance from the central axis of rotation to the acceleration detection point of the sensor is known, accurate angular acceleration cannot be detected.

[0006] Furthermore, with the technique of mounting the rotation sensor that detects angular velocity on an inspection table and calibrating the rotation sensor by rotating the inspection table, it is difficult to calibrate a rotation sensor that has already been incorporated into a rotating body to be measured and has begun actual operation. For example, the work of removing the rotation sensor from the rotating body, calibrating it using the inspection table, and then re-installing the rotation sensor into the rotating body after calibration is a heavy burden. Furthermore, there are cases where it is simply not possible to remove the rotation sensor from the rotating body.

[0007] Furthermore, according to this technique, for example, calibration of a rotation sensor used to detect the rotation of a rotating shaft cannot be performed in a state similar to that of the rotation sensor during actual operation. It is also conceivable to detect angular acceleration by differentiating the angular velocity detected by a rotation sensor calibrated using this technology, but in this case, errors from integration during calibration and differentiation during angular acceleration detection will be superimposed on the detected angular acceleration, preventing accurate detection of angular acceleration. Therefore, an object of the present invention is to accurately detect angular acceleration without requiring an accurate distance from the rotation center axis to the acceleration detection point of the acceleration sensor. Another object of the present invention is to calibrate a rotation sensor that is used to detect the rotation of a rotating shaft in an actual operating state or in a state similar to that in the actual operating state. [Means for solving the problem]

[0008] To achieve the above object, the present invention provides a rotation measurement system for measuring the angular acceleration of a rotating shaft having a cylindrical or columnar shape centered around a central axis of rotation and a first portion and a second portion having different radii. The rotation measurement system includes a first acceleration sensor and a second acceleration sensor fixed on the outer circumferential surface of the first portion at positions line-symmetrical with respect to the central axis of rotation, a third acceleration sensor and a fourth acceleration sensor fixed on the outer circumferential surface of the second portion at positions line-symmetrical with respect to the central axis of rotation, and angular acceleration measuring means. The first acceleration sensor and the second acceleration sensor detect acceleration in a tangential direction of a first circle centered around the central axis of rotation, and the third acceleration sensor and the fourth acceleration sensor detect acceleration in a tangential direction of a second circle centered around the central axis of rotation. The angular acceleration measuring means includes first tangential acceleration calculating means for calculating a first tangential acceleration, which is the tangential acceleration at a position on the first circle, from the accelerations detected by the first acceleration sensor and the second acceleration sensor; second tangential acceleration calculating means for calculating a second tangential acceleration, which is the tangential acceleration at a position on the second circle, from the accelerations detected by the third acceleration sensor and the fourth acceleration sensor; and angular acceleration calculating means for calculating the angular acceleration of the rotating shaft from the difference in radii between the first portion and the second portion and the first tangential acceleration and the second tangential acceleration, by assuming that the difference between the first tangential acceleration and the second tangential acceleration is caused by the difference in radii.

[0009] In this rotation measurement system, the accelerations detected by the first acceleration sensor and the second acceleration sensor may be equally positive and negative in the same circumferential direction, and the accelerations detected by the third acceleration sensor and the fourth acceleration sensor may be equally positive and negative in the same circumferential direction. In this case, the difference in radius between the first portion and the second portion may be rd, the acceleration detected by the first acceleration sensor may be SA1, the acceleration detected by the second acceleration sensor may be SB1, the acceleration detected by the third acceleration sensor may be SA2, and the acceleration detected by the fourth acceleration sensor may be SB2, and the first tangential acceleration calculation means calculates the first tangential acceleration Ta1 as follows: Ta1=(SA1+SB1) / 2 Calculate according to The second tangential acceleration calculation means calculates the second tangential acceleration Ta2 as follows: Ta2=(SA2+SB2) / 2 The angular acceleration calculation means calculates the angular acceleration α of the rotating shaft according to the following formula: α={(Ta1×Ta2)-Ta1 2} / (Ta1×rd) It can be calculated according to:

[0010] The above rotation measurement system may further include a first adjustment means, a second adjustment means, and an adjustment amount setting means. The first adjustment means adjusts at least one of the acceleration detected by the first acceleration sensor and the acceleration detected by the second acceleration sensor by a set first adjustment amount, and the second adjustment means adjusts at least one of the acceleration detected by the third acceleration sensor and the acceleration detected by the fourth acceleration sensor by a set second adjustment amount. Furthermore, the accelerations detected by the first acceleration sensor and the second acceleration sensor are made equal in positive and negative sign in the same circumferential direction, and the accelerations detected by the third acceleration sensor and the fourth acceleration sensor are made equal in positive and negative sign in the same circumferential direction, and the adjustment amount setting means sets the first adjustment amount so that the sum of the accelerations detected by the first acceleration sensor and the second acceleration sensor after adjustment by the first adjustment means becomes zero when the angular acceleration of the rotating shaft is zero, and sets the second adjustment amount so that the sum of the accelerations detected by the third acceleration sensor and the fourth acceleration sensor after adjustment by the second adjustment means becomes zero when the angular acceleration of the rotating shaft is zero.

[0011] To achieve the above object, the present invention provides a rotation measurement system for measuring the angular acceleration of a rotating shaft having a cylindrical or columnar shape with a central axis of rotation and three or more sections with different radii. The rotation measurement system includes a sensor set corresponding to each of the three or more sections and angular acceleration measurement means. Each sensor set has a first acceleration sensor and a second acceleration sensor fixed on the outer circumferential surface of the corresponding section at positions that are line-symmetrical with respect to the central axis of rotation, and the first acceleration sensor and the second acceleration sensor of each sensor set detect acceleration in the tangential direction of a circle that is centered around the central axis of rotation and corresponds to the sensor set. The angular acceleration measuring means includes: a tangential acceleration calculating means for calculating, for each sensor set, a tangential acceleration at a position on a circle corresponding to the sensor set from the accelerations detected by the first acceleration sensor and the second acceleration sensor of the sensor set; an angular acceleration calculating means for calculating, for each of two or more combinations of two sensor sets, a virtual angular acceleration of the rotating shaft from the two tangential accelerations calculated by the tangential acceleration calculating means for the two sensor sets included in the combination and the difference in radii of the portions corresponding to the two sensor sets included in the combination, assuming that the difference between the two tangential accelerations is caused by the difference in radii; and an angular acceleration determining means for statistically calculating the angular acceleration of the rotating shaft from the two or more virtual angular accelerations calculated by the angular acceleration calculating means for each of the two or more combinations.

[0012] In this rotation measurement system, the accelerations detected by the first acceleration sensor and the second acceleration sensor of each sensor set are set to be equal in sign in the same circumferential direction, and the tangential acceleration calculation means calculates the tangential acceleration Ta for each sensor set by defining the acceleration detected by the first acceleration sensor of the sensor set as SA and the acceleration detected by the second acceleration sensor as SB, as follows: Ta=(SA+SB) / 2 In this case, the angular acceleration calculation means may calculate the accelerations Ta according to the following formula: For each of two or more combinations of two sensor sets, the two tangential accelerations Ta calculated by the tangential acceleration calculation means for the two sensor sets included in the combination are defined as Ta1 and Ta2, and the difference between the radii of the portions corresponding to the two sensor sets included in the combination is defined as rd. The virtual angular acceleration α is α={(Ta1×Ta2)-Ta1 2} / (Ta1×rd) It may be found according to

[0013] According to the rotation measurement system described above, it is possible to accurately detect angular acceleration using the difference in radius between the portions of the rotating shaft to which the acceleration sensor is fixed, without needing to accurately measure the distance from the central axis of rotation to the acceleration detection point of the acceleration sensor. The present invention also provides a calibration system for a rotation sensor that measures the angular acceleration or angular velocity of the rotating shaft, the calibration system including a rotation measurement system, wherein the calibration system for a rotation sensor includes calibration means that calibrates the rotation sensor so that the measurement value of the rotation sensor matches the angular acceleration calculated by the rotation measurement system.

[0014] According to such a rotation sensor calibration system, the rotation sensor can be calibrated in an actual operation state or in a state similar to the actual operation state, in which the rotation sensor measures the angular acceleration or angular velocity of a rotating shaft. [Effects of the Invention]

[0015] As described above, according to the present invention, it is possible to detect accurate angular acceleration without needing to know the exact distance from the rotation center axis to the acceleration detection point of the acceleration sensor. Furthermore, according to the present invention, a rotation sensor applied to detect the rotation of a rotating shaft can be calibrated in an actual operating state or in a state similar to that in actual operation. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a configuration of a calibration system according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing the arrangement of an acceleration sensor according to an embodiment of the present invention; [Figure 3] FIG. 2 is a diagram showing the configuration of a first tangential acceleration measuring unit according to the embodiment of the present invention. [Figure 4] 3A and 3B are diagrams illustrating accelerations detected by an acceleration sensor according to an embodiment of the present invention. [Figure 5] 5A and 5B are diagrams illustrating an example of a mechanism for fixing an acceleration sensor according to an embodiment of the present invention. [Figure 6] FIG. 10 is a diagram illustrating another exemplary configuration of a calibration system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] A calibration system according to an embodiment of the present invention will be described below. Figure 1 shows the configuration of the calibration system. This calibration system is a system for calibrating a rotation sensor 100 that detects the angular acceleration of a rotating shaft 11 in a rotation mechanism that includes a rotating shaft 11, a rotational power 12, and a bearing 13 that supports the rotating shaft 11. Here, this rotation mechanism may be provided as equipment for calibrating various types of rotation sensors 100, or may be equipment that is actually used on-site in a form in which the rotation sensor 100 is applied. Furthermore, the rotation sensor 100 to be calibrated may be a sensor that detects angular acceleration and may use any detection method. For example, the rotation sensor 100 may be a mechanical, optical, or vibration type angular acceleration sensor. In the rotation mechanism, rotational power 12, such as a motor or a manual flywheel, rotates and drives rotating shaft 11. Rotating shaft 11 has a shape in which first shaft portion 111, second shaft portion 112, third shaft portion 113, and fourth shaft portion 114, each of which is cylindrical or cylindrical, are arranged coaxially around the central axis of rotation of rotating shaft 11, and at least second shaft portion 112 and third shaft portion 113 have different radii.

[0018] Furthermore, although FIG. 1 illustrates rotation sensor 100 as detecting the angular acceleration of first shaft portion 111, rotation sensor 100 may detect the angular acceleration of any shaft portion. The calibration system also includes a first sensor set 2 consisting of acceleration sensors A1 and B1 fixed to the second shaft portion 112, a second sensor set 3 consisting of acceleration sensors A2 and B2 fixed to the third shaft portion 113, and a calibration processing device 4.

[0019] The calibration processing device 4 also includes a calibration target sensor angular acceleration measurement unit 41, a first tangential acceleration measurement unit 42, a second tangential acceleration measurement unit 43, a reference angular acceleration calculation unit 44, a calibration unit 45, and a control unit 46 that controls each of the above units. Next, FIG. 2a shows the arrangement of acceleration sensors A1 and B1 of first sensor set 2 and acceleration sensors A2 and B2 of second sensor set 3 as viewed in the axial direction of the central axis of rotation of rotating shaft 11. As shown in the figure, acceleration sensor A1 and acceleration sensor B1 of the first sensor set 2 are fixed on the outer surface of the second shaft portion 112 at positions that are symmetrical with respect to the rotational center axis C of the rotating shaft 11 (positions in the opposite direction when viewed from the rotational center axis C). In addition, acceleration sensor A2 and acceleration sensor B2 of the second sensor set 3 are fixed at positions on the outer surface of the third shaft portion 113 that are symmetrical with respect to the rotation center axis C of the rotating shaft 11 (positions in the opposite direction when viewed from the rotation center axis C). Acceleration sensors A1, B1, A2, and B2 are uniaxial acceleration sensors, and capacitance-type MEMS sensors can be used as such uniaxial acceleration sensors. Generally, capacitance-type acceleration sensors can detect DC components of acceleration, so there is no lower frequency limit for their response. However, other types of acceleration sensors may be used depending on the measurement application. For example, piezoelectric acceleration sensors may be used in applications requiring high resolution of the acceleration magnitude.

[0020] Acceleration sensors A1, B1, A2, and B2 are all of the same specification (same model number), so the relative position / distance of the acceleration detection point of each acceleration sensor to the fixed point of the acceleration sensor (the outer surface of the shaft) is the same.

[0021] 2a, acceleration sensor A1 is oriented to detect acceleration SA1 acting in the tangential direction of a circle that is centered on rotation axis C and passes through the acceleration detection point of acceleration sensor A1, and acceleration sensor B1 is oriented to detect acceleration SB1 acting in the tangential direction of a circle that is centered on rotation axis C and passes through the acceleration detection point of acceleration sensor B1. As the positive direction is indicated by "+", the positive direction of acceleration SA1 detected by acceleration sensor A1 and the positive direction of acceleration SB1 detected by acceleration sensor B1 are set in the tangential direction facing the same rotation direction, but are opposite directions when viewed from a fixed system that does not rotate with rotating shaft 11 and is fixed relative to the Earth.

[0022] Similarly, acceleration sensor A2 is oriented to detect acceleration SA2 acting in the tangential direction of a circle centered on rotation axis C and passing through the acceleration detection point of acceleration sensor A2, and acceleration sensor B2 is oriented to detect acceleration SB2 acting in the tangential direction of a circle centered on rotation axis C and passing through the acceleration detection point of acceleration sensor B2. As the positive direction is indicated by "+", the positive direction of acceleration SA2 detected by acceleration sensor A2 and the positive direction of acceleration SB2 detected by acceleration sensor B2 are set in the tangential direction facing the same rotation direction, and are opposite directions when viewed from a fixed system that does not rotate with rotating shaft 11 and is fixed relative to the Earth.

[0023] Hereinafter, as shown in Figure 2b, the distance from the rotation center axis C to the acceleration detection point of acceleration sensor A1 and the distance to the acceleration detection point of acceleration sensor B1 will be represented by r1, and the distance from the rotation center axis C to the acceleration detection point of acceleration sensor A2 and the distance to the acceleration detection point of acceleration sensor B2 will be represented by r2.

[0024] However, it is difficult to accurately determine r1 and r2, and in this embodiment, they are treated as unknown values. In the following, the difference in radius between the second shaft portion 112 and the third shaft portion 113 will be represented by rd. This difference in radius rd can be easily and accurately measured by directly measuring the difference or by measuring the diameters of the second shaft portion 112 and the third shaft portion 113, and in this embodiment, it is assumed to be a known value measured in advance.

[0025] Returning to FIG. 1, the calibration target sensor angular acceleration measuring unit 41 of the calibration processing device 4 measures the angular acceleration α 0 of the rotating shaft 11 from the output of the rotation sensor 100 using default measurement parameters and outputs the result to the calibration unit 45 . The first tangential acceleration measuring unit 42 calculates a first tangential acceleration Ta1 at a position radially away from the rotation center axis C by a distance r1 from the accelerations SA1 and SB1 detected by the acceleration sensors A1 and B2 of the first sensor set 2. In addition, the second tangential acceleration measuring unit 43 calculates the second tangential acceleration Ta2 at a position radially away from the rotation center axis C by a distance r2 from the accelerations SA2 and SB2 detected by the acceleration sensors A2 and B2 of the second sensor set 3. The calculation of the first tangential acceleration Ta1 by the first tangential acceleration measuring unit 42 and the calculation of the second tangential acceleration Ta2 by the second tangential acceleration measuring unit 43 will be described below. First, the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measuring unit 42 will be described. FIG. 3 shows the configuration of the first tangential acceleration measuring unit 42. As shown in the figure, the first tangential acceleration measuring unit 42 includes a wireless interface 421 that receives the acceleration SA1 wirelessly transmitted by the acceleration sensor A1 of the first sensor set 2 and the acceleration SB2 wirelessly transmitted by the acceleration sensor b1 of the first sensor set 2, a gain / offset adjustment unit 422, an addition unit 423, and an arithmetic processing unit 424.

[0026] The gain / offset adjustment unit 422 adjusts the gain and offset of the acceleration SA1 received by the wireless interface 421 so that they are equal to the gain and offset of the acceleration SB1 received by the wireless interface 421, and outputs the result to the addition unit 423. The addition unit 423 adds the output of the gain / offset adjustment unit 422 and the acceleration SB1 received by the wireless interface 421, and sends the result to the calculation processing unit 424.

[0027] The calculation processing unit 424 multiplies the output of the adding unit 423 by 1 / 2 to obtain a value as the first tangential acceleration Ta1, and sends the result to the reference angular acceleration calculation unit 44. As shown in FIG. 4, let Ta1 denote the tangential acceleration applied to acceleration sensors A1 and B1 due to the angular acceleration α of rotating shaft 11, g denote the acceleration of gravity, b denote the acceleration applied to rotating shaft 11 in a direction perpendicular to the central axis C of rotation of rotating shaft 11 due to a disturbance, and let gx denote the positive component of the gravitational acceleration g on the detection axis of acceleration sensor A1, and bx denote the positive component of the acceleration b due to the disturbance on the detection axis of acceleration sensor A1. When rotating shaft 11 has rotated by θ from the angle at which acceleration sensor A1 is located at the top of second shaft portion 112 as viewed from the fixed system, the acceleration SA1 detected by acceleration sensor A1 and the acceleration SB1 detected by acceleration sensor B1 can be expressed by the following equations when the gains and offsets of the first acceleration sensor and the second acceleration sensor are equal.

[0028] SA1=Ta1+gx+bx SB1=Ta1-gx-bx Therefore, SA1 + SB1 = 2Ta1, and the first tangential acceleration Ta1 is This can be calculated as Ta1=(SA1+SB1) / 2.

[0029] Therefore, the addition unit 423 adds the acceleration SA1, whose gain and offset have been adjusted by the gain / offset adjustment unit 422, to the acceleration SB1, and the calculation processing unit 424 multiplies the output of the addition unit 423 by 1 / 2, thereby calculating the first tangential acceleration Ta1. Here, the amounts of gain and offset adjustment performed by gain / offset adjustment section 422 will be described. Prior to starting the measurement, the operator instructs the control unit 46 to perform calibration while the angular velocity of the rotating shaft 11 is kept constant, preferably while the rotating shaft 11 is stationary. Upon receiving the instruction to perform calibration, the control unit 46 instructs the gain / offset adjustment unit 422 to perform a calibration operation for adjusting the gain and offset. Upon receiving the instruction, the gain / offset adjustment unit 422 performs a calibration operation and sets the gain and offset adjustment values ​​to be applied to the acceleration SA1 so that the output of the addition unit 423, which is the sum signal of the output of the gain / offset adjustment unit 422 and the acceleration SB1, becomes 0.

[0030] Here, when the angular velocity of the rotating shaft 11 is constant or the rotating shaft 11 is stationary, the angular acceleration α of the rotating shaft 11 is 0, and the first tangential acceleration Ta1 applied to the acceleration sensors A1 and B1 is 0. If the gains and offsets of the accelerations SA1 and SB1 are equal, the sum signal SA1+SB1 is expressed as follows: SA1+SB1=(gx+bx)+(-gx-bx)=0.

[0031] Alternatively, when there is no disturbance b, SA1+SB1=(gx)+(-gx)=0. Therefore, by setting the amount of gain and offset adjustment applied to acceleration SA1 so that the sum signal output by addition unit 423 becomes 0, the output of gain / offset adjustment unit 422 can be adjusted to the signal that acceleration sensor A1 would output if the acceleration detection gain and offset characteristics of acceleration sensor A1 were equal to those of acceleration sensor B1.As a result, with the output of gain / offset adjustment unit 422 as SA1 and the output of the second acceleration sensor as SB1, the above-mentioned SA1+SB1=2Ta1 and Ta1=(SA1+SB1) / 2 hold.

[0032] The calculation of the first tangential acceleration Ta1 has been described above. Next, the calculation of the second tangential acceleration Ta2 in the second tangential acceleration measuring unit 43 is performed using the same configuration and operation as the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measuring unit 42, and the explanation thereof is the same as the explanation of the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measuring unit 42 above, except that acceleration sensor A1 is replaced with acceleration sensor A2, acceleration sensor B1 is replaced with acceleration sensor B2, acceleration SA1 is replaced with acceleration SA2, acceleration SB1 is replaced with acceleration SB2, and first tangential acceleration Ta1 is replaced with second tangential acceleration Ta2.

[0033] Returning to FIG. 1, the reference angular acceleration calculation unit 44 calculates the angular acceleration α of the rotating shaft 11 from the first tangential acceleration Ta1 sent from the first tangential acceleration measurement unit 42, the second tangential acceleration Ta2 sent from the second tangential acceleration measurement unit 43, and the known difference rd between the radii of the second shaft portion 112 and the third shaft portion 113, and sends it to the calibration unit 45 as the reference angular acceleration α.

[0034] That is, as shown in Figure 2b, (Formula 1) r2=r1+rd where tangential acceleration = radius × angular acceleration, angular acceleration = tangential acceleration / radius. The angular acceleration of the second shaft portion 112 and the angular acceleration of the third shaft portion 113 are the same angular acceleration α of the rotating shaft 11 and are therefore equal. Therefore, the difference between the first tangential acceleration Ta1 and the second tangential acceleration Ta2 can be considered to be caused by the difference in radius. (Formula 2) Ta1 / r1=Ta2 / r2 Substituting Equation 1 into Equation 2, we get (Equation 3) Ta1 / r1=Ta2 / (r1+rd).

[0035] Solving equation 3 for r1 gives (Equation 4) r1 = (Ta1 × rd) / (Ta2 - Ta1), α=Ta1 / r1 Substituting into (Formula 5) Ta1×(Ta2-Ta1) / (Ta1×rd)={(Ta1×Ta2)-Ta1 2} / (Ta1×rd).

[0036] Therefore, the reference angular acceleration calculation unit 44 calculates the angular acceleration α according to Equation 5 and sends it to the calibration unit 45 as the reference angular acceleration α. The calibration unit 45 calibrates the rotation sensor 100 using the angular acceleration α0 of the rotating shaft 11 measured by the calibration target sensor angular acceleration measurement unit 41 from the output of the rotation sensor 100 and the reference angular acceleration α sent from the reference angular acceleration calculation unit 44. That is, the calibration unit 45 calculates, as calibration information, correction parameters such as gain and offset, which, when applied to the angular acceleration α0, will cause the corrected angular acceleration α0 to match the reference angular acceleration α. If the rotation sensor 100 has a function of accepting the setting of the correction parameters and correcting the output in accordance with the set correction parameters, the correction parameters calculated as calibration information are set in the rotation sensor 100. Alternatively, if the calibration target sensor angular acceleration measuring unit 41 is also used to detect angular acceleration using the rotation sensor 100 during actual operation, correction parameters calculated as calibration information may be set in the calibration target sensor angular acceleration measuring unit 41, and during actual operation, the calibration target sensor angular acceleration measuring unit 41 may correct the output of the rotation sensor 100 according to the set correction parameters.

[0037] Alternatively, the calibration information may be transferred to and set in a measurement device that detects angular acceleration using the rotation sensor 100 during actual operation, and the output of the rotation sensor 100 may be corrected and used in the measurement device according to the correction parameters represented by the set calibration information. Next, acceleration sensors A1 and B1 may be fixed to the second shaft portion 112, and acceleration sensors A2 and B2 to the third shaft portion 113, in any manner, such as by screwing, gluing, magnetic force, wrapping a band for fixing the acceleration sensors around the shaft portions, or using other fixing devices. However, for reasons such as calibration of tangential acceleration detection, it is preferable that acceleration sensors A1, B1, A2, and B2 be fixed in a detachable manner.

[0038] For example, a sensor set consisting of acceleration sensor A and acceleration sensor B can be fixed to shaft portion P using the fixing tool shown in FIG. 5a shows the state as seen from a direction perpendicular to the central axis of rotation C, FIG. 5b shows the state as seen from the axial direction of the central axis of rotation C, and FIG. 5c shows the state as seen obliquely. As shown in the figure, this device has a structure in which a first base 501 and a second base 502 each having roughly the shape of a cylinder divided into upper and lower halves with a hollow section penetrating through the center in the vertical and horizontal directions in the front-to-back direction, are connected vertically by a bolt 503. Furthermore, as shown in Figure 5d, this device is used by arranging the separated first base 501 and second base 502 so that the shaft portion P is located between them, and then fastening the first base 501 and the second base 502 with bolts 503 to sandwich the shaft portion P and thereby fixing it to the shaft portion P so that it rotates together with the shaft portion P.

[0039] Furthermore, the hollow portion of this device has a shape such that, when fixed to the shaft portion P, a predetermined portion on the hollow portion side of the first base 501 and a predetermined portion on the hollow portion side of the second base 502 contact each other at opposing positions on the outer surface of the shaft portion P. An acceleration sensor A is fixed to a portion of the first base 501 that contacts the outer circumferential surface of the shaft portion P, and an acceleration sensor B is fixed to a portion of the second base 502 that contacts the outer circumferential surface of the shaft portion P. The embodiments of the present invention have been described above. In the above-described Figures 1, 2, and 4, acceleration sensors A1 and A2, and acceleration sensors B1 and B2 are arranged in positions where the direction seen from the central axis of rotation C is the same (positions where the rotation phase is the same), but they may also be arranged in positions where the direction seen from the central axis of rotation C is different, as shown in Figure 6a, for example.

[0040] In addition, in the above, sensor sets (first sensor set 2 and second sensor set 3) are provided on two shaft portions having different diameters, the second shaft portion 112 and the third shaft portion 113, but sensor sets SS1-SS3 may also be provided on each of three or more shaft portions having different diameters, as shown in Figure 6b, for example.

[0041] In this case, a combination of any two sensor sets may be defined as a sensor set, and for two or more sensor sets, angular acceleration α may be measured in the same manner as in the above embodiment using the first sensor set 2 and the second sensor set 3, and the final angular acceleration α may be calculated by statistical processing from the angular acceleration α measured for each sensor set. The statistical processing may, for example, involve calculating the average value of the angular acceleration α measured for each sensor set as the final angular acceleration α. ​​Alternatively, the statistical processing may involve calculating the median, mode, or other representative value as the final angular acceleration α.

[0042] In the above embodiment, the sensor set may be provided on the shaft portion where the rotation sensor 100 is disposed. Furthermore, the reference angular acceleration calculation unit 44 of the calibration system of the above embodiment may also measure the angular velocity ω of the rotating shaft 11 by integrating the measured angular acceleration α. ​​In this case, the rotation sensor 100 to be calibrated may be an angular velocity sensor that detects the angular velocity of the rotating shaft 11, and the rotation sensor 100 may be calibrated so that the angular velocity measured by the rotation sensor 100 coincides with the angular velocity ω calculated from the angular acceleration α. Furthermore, the calibration system shown in the above embodiment may be configured as a rotation measurement system that measures angular acceleration α using sensor sets arranged on shaft portions with different diameters, excluding the calibration target sensor angular acceleration measurement unit 41 and the calibration unit 45. In this case, the rotation measurement system may also measure angular velocity ω of the rotating shaft 11 by integrating the measured angular acceleration α.

[0043] As described above, according to this embodiment, it is possible to accurately detect angular acceleration and the angular velocity based thereon from the difference in radius between the portions of the rotating shaft 11 where the sensor sets are fixed, without needing to know the exact distance from the rotation center axis C to the acceleration detection point of the acceleration sensor. Furthermore, according to this embodiment, the rotation sensor 100 can be calibrated in an actual operation state where the rotation sensor 100 measures the angular acceleration and angular velocity of the rotating shaft 11, or in a state similar to that during actual operation. [Explanation of symbols]

[0044] 2...first sensor set, 3...second sensor set, 4...calibration processing device, 11...rotating shaft, 12...rotational power, 13...bearing, 41...calibration target sensor angular acceleration measurement unit, 42...first tangential acceleration measurement unit, 43...second tangential acceleration measurement unit, 44...reference angular acceleration calculation unit, 45...calibration unit, 46...control unit, 100...rotation sensor, 111...first shaft portion, 112...second shaft portion, 113...third shaft portion, 114...fourth shaft portion, 421...wireless interface, 422...gain / offset adjustment unit, 423...addition unit, 424...arithmetic processing unit, 501...first base, 502...second base, 503...bolt.

Claims

1. A rotation measurement system for measuring angular acceleration of a rotating shaft having a columnar or cylindrical shape with a central axis of rotation and a first portion and a second portion having different radii, a first acceleration sensor and a second acceleration sensor fixed on an outer peripheral surface of the first portion at positions that are symmetrical with respect to the rotation center axis; a third acceleration sensor and a fourth acceleration sensor fixed on an outer peripheral surface of the second portion at positions that are symmetrical with respect to the rotation center axis; and angular acceleration measuring means; the first acceleration sensor and the second acceleration sensor detect acceleration in a tangential direction of a first circle having the rotation central axis as a central axis, and the third acceleration sensor and the fourth acceleration sensor detect acceleration in a tangential direction of a second circle having the rotation central axis as a central axis, The angular acceleration measuring means a first tangential acceleration calculation means for calculating a first tangential acceleration, which is a tangential acceleration at a position on the first circle, from the accelerations detected by the first acceleration sensor and the second acceleration sensor; second tangential acceleration calculation means for calculating a second tangential acceleration, which is a tangential acceleration at a position on the second circle, from the accelerations detected by the third acceleration sensor and the fourth acceleration sensor; and angular acceleration calculation means for calculating the angular acceleration of the rotating shaft from a difference in radius between the first portion and the second portion and the first tangential acceleration and the second tangential acceleration, by assuming that the difference between the first tangential acceleration and the second tangential acceleration is caused by the difference in radius.

2. 2. The rotation measurement system according to claim 1, the accelerations detected by the first acceleration sensor and the second acceleration sensor are equal in sign to the positive and negative signs in the same circumferential direction, and the accelerations detected by the third acceleration sensor and the fourth acceleration sensor are equal in sign to the positive and negative signs in the same circumferential direction, The difference in radius between the first portion and the second portion is defined as rd, the acceleration detected by the first acceleration sensor is defined as SA1, the acceleration detected by the second acceleration sensor is defined as SB1, the acceleration detected by the third acceleration sensor is defined as SA2, and the acceleration detected by the fourth acceleration sensor is defined as SB2, The first tangential acceleration calculation means calculates the first tangential acceleration Ta1 as follows: Ta1=(SA1+SB1) / 2 Calculated according to The second tangential acceleration calculation means calculates the second tangential acceleration Ta2 as follows: Ta2=(SA2+SB2) / 2 Calculated according to The angular acceleration calculation means calculates the angular acceleration α of the rotating shaft as α={(Ta1×Ta2)-Ta1 2 } / (Ta1×rd) A rotation measurement system characterized by calculating the rotation speed according to the following formula.

3. 2. The rotation measurement system according to claim 1, A first adjustment means; A second adjustment means; an adjustment amount setting means; the accelerations detected by the first acceleration sensor and the second acceleration sensor are equal in sign to the positive and negative signs in the same circumferential direction, and the accelerations detected by the third acceleration sensor and the fourth acceleration sensor are equal in sign to the positive and negative signs in the same circumferential direction, the first adjustment means adjusts at least one of the acceleration detected by the first acceleration sensor and the acceleration detected by the second acceleration sensor by a set first adjustment amount; the second adjustment means adjusts at least one of the acceleration detected by the third acceleration sensor and the acceleration detected by the fourth acceleration sensor by a set second adjustment amount; the adjustment amount setting means sets the first adjustment amount so that a sum of the accelerations detected by the first acceleration sensor and the second acceleration sensor after adjustment by the first adjustment means becomes zero when the angular acceleration of the rotating shaft is zero, and sets the second adjustment amount so that a sum of the accelerations detected by the third acceleration sensor and the fourth acceleration sensor after adjustment by the second adjustment means becomes zero when the angular acceleration of the rotating shaft is zero.

4. A rotation measurement system for measuring angular acceleration of a rotating shaft having a cylindrical or columnar shape with a central axis of rotation and having three or more portions with different radii, a sensor set corresponding to each of the three or more portions; and angular acceleration measuring means; each of the sensor sets includes a first acceleration sensor and a second acceleration sensor fixed to an outer peripheral surface of the corresponding portion at positions that are symmetrical with respect to the rotation center axis; the first acceleration sensor and the second acceleration sensor of each sensor set detect acceleration in a tangential direction of a circle corresponding to the sensor set, the circle having the rotation central axis as a central axis; The angular acceleration measuring means tangential acceleration calculation means for calculating, for each sensor set, a tangential acceleration at a position on a circle corresponding to the sensor set from accelerations detected by the first acceleration sensor and the second acceleration sensor of the sensor set; angular acceleration calculation means for calculating a virtual angular acceleration of the rotating shaft for each of two or more combinations of two of the sensor sets, based on two tangential accelerations calculated by the tangential acceleration calculation means for the two sensor sets included in the combination and a difference in radii of the portions corresponding to the two sensor sets included in the combination, by assuming that the difference between the two tangential accelerations is caused by the difference in radii; and angular acceleration determining means for statistically calculating the angular acceleration of the rotating shaft from two or more virtual angular accelerations calculated by the angular acceleration calculating means for each of the two or more combinations.

5. 5. The rotation measurement system according to claim 4, the accelerations detected by the first acceleration sensor and the second acceleration sensor of each sensor set are equal in sign to the positive and negative in the same circumferential direction, The tangential acceleration calculation means calculates the tangential acceleration Ta for each sensor set by defining the acceleration detected by the first acceleration sensor of the sensor set as SA and the acceleration detected by the second acceleration sensor as SB, as follows: Ta = (SA + SB) / 2 Calculated according to The angular acceleration calculation means, for each of two or more combinations of two of the sensor sets, defines two tangential accelerations Ta calculated by the tangential acceleration calculation means for the two sensor sets included in the combination as Ta1 and Ta2, defines a difference in radii of the portions corresponding to the two sensor sets included in the combination as rd, The virtual angular acceleration α is α={(Ta1×Ta2)-Ta1 2 } / (Ta1×rd) A rotation measurement system characterized by determining the rotational speed according to the following:

6. A calibration system for a rotation sensor that measures the angular acceleration or angular acceleration of a rotating shaft, comprising the rotation measurement system according to claim 1, 2, 3, 4 or 5, A calibration system for a rotation sensor, comprising: calibration means for calibrating the rotation sensor so that the measurement value of the rotation sensor matches the angular acceleration calculated by the rotation measurement system.

7. A rotation measurement method for measuring angular acceleration of a rotating shaft, comprising: a step of fixing a first acceleration sensor and a second acceleration sensor to an outer peripheral surface of a first portion of a columnar or cylindrical shape having a central axis of rotation of the rotating shaft, at positions that are line-symmetrical with respect to the central axis of rotation, so as to detect acceleration in a tangential direction of a first circle having a central axis of rotation as the central axis; a step of fixing a third acceleration sensor and a fourth acceleration sensor to positions on an outer peripheral surface of a second portion of the rotating shaft having a cylindrical or columnar shape with the central axis of rotation of the rotating shaft, the second portion having a radius different from that of the first portion, and which are symmetrical with respect to the central axis of rotation, so as to detect acceleration in a tangential direction of a second circle having the central axis of rotation as a central axis; calculating a first tangential acceleration, which is a tangential acceleration at a position on the first circle, from the accelerations detected by the first acceleration sensor and the second acceleration sensor; calculating a second tangential acceleration, which is a tangential acceleration at a position on the second circle, from the accelerations detected by the third acceleration sensor and the fourth acceleration sensor; calculating an angular acceleration of the rotating shaft from a difference in radius between the first portion and the second portion and the first tangential acceleration and the second tangential acceleration, assuming that the difference between the first tangential acceleration and the second tangential acceleration is caused by the difference in radius.

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