Rotor measuring system, rotor sensor calibration system, and rotor measuring 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 for measuring angular acceleration and calibration of a rotation sensor using the rotation measurement system.

Background Art

[0002] As a technique for detecting angular acceleration, tangential acceleration is detected using two acceleration sensors provided at positions symmetric with respect to the rotation center axis, and angular acceleration is calculated from the detected tangential acceleration by utilizing the fact that the tangential acceleration is proportional to the angular acceleration (for example, Patent Documents 1 and 2).

[0003] Also, as a technique for calibrating a rotation sensor, a test bench equipped with a rotation sensor for detecting angular velocity is rotated by a reference angle, and the rotation sensor is calibrated from the difference between the integrated value of the angular velocity detected by the rotation sensor with respect to the rotation and the reference angle (for example, Patent Documents 3 and 4).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

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

[0006] Also, according to the technique of mounting the rotation sensor for detecting the angular velocity described above on the inspection table and rotating the inspection table to calibrate the rotation sensor, it is difficult to calibrate the rotation sensor that has already been incorporated into the rotating body to be measured and whose actual operation has started. For example, the burden of removing the rotation sensor from the rotating body, calibrating it using the inspection table, and then re-incorporating the rotation sensor into the rotating body is large. Also, there may be cases where the rotation sensor itself cannot be removed from the rotating body.

[0007] Also, according to this technique, for example, the calibration of the rotation sensor applied to the detection of the rotation of the rotating shaft cannot be performed with the rotation sensor in the same state as during actual operation. Also, it is conceivable to detect the angular acceleration by differentiating the angular velocity detected by the rotation sensor calibrated by this technique. However, in this case, the error between the integration during calibration and the differentiation during angular acceleration detection is superimposed on the detected angular acceleration, which hinders the accurate detection of the angular acceleration. Therefore, an object of the present invention is to accurately detect the angular acceleration without requiring the exact distance from the rotation center axis to the acceleration detection point of the acceleration sensor. Also, concomitantly, an object of the present invention is to calibrate the rotation sensor applied to the detection of the rotation of the rotating shaft in the actual operation state or a state similar to that during actual operation.

Means for Solving the Problems

[0008] To achieve the above object, the present invention provides a rotational measurement system for measuring the angular acceleration of a rotating shaft having a cylindrical or cylindrical shape with a central axis of rotation, and having a first portion and a second portion that are different in radius from each other. This rotational measurement system includes a first acceleration sensor and a second acceleration sensor fixed at positions on the outer peripheral surface of the first portion that are line-symmetric with respect to the rotation central axis, a third acceleration sensor and a fourth acceleration sensor fixed at positions on the outer peripheral surface of the second portion that are line-symmetric with respect to the rotation central axis, and an angular acceleration measurement means. Further, the first acceleration sensor and the second acceleration sensor detect the acceleration in the tangential direction of a first circle having the rotation central axis as its central axis, and the third acceleration sensor and the fourth acceleration sensor detect the acceleration in the tangential direction of a second circle having the rotation central axis as its central axis. Then, the angular acceleration measurement means includes a first tangential acceleration calculation 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, a second tangential acceleration calculation 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 an angular acceleration calculation means for calculating the angular acceleration of the rotating shaft by assuming that the difference between the first tangential acceleration and the second tangential acceleration is caused by the difference in radius between the first portion and the second portion.

[0009] Here, in this rotational measurement system, the positive and negative of the accelerations detected by the first acceleration sensor and the second acceleration sensor in the same circumferential direction may be made equal, and the positive and negative of the accelerations detected by the third acceleration sensor and the fourth acceleration sensor in the same circumferential direction may be made equal. And in this case, assuming that the difference in radius between the first portion and the second portion is rd, the acceleration detected by the first acceleration sensor is SA1, the acceleration detected by the second acceleration sensor is SB1, the acceleration detected by the third acceleration sensor is SA2, and the acceleration detected by the fourth acceleration sensor is SB2, the first tangential acceleration calculation means calculates the first tangential acceleration Ta1 as Ta1 = (SA1 + SB1) / 2 is calculated according to The second tangential acceleration calculating means calculates the second tangential acceleration Ta2 as Ta2 = (SA2 + SB2) / 2 and can be calculated according to. Further, the angular acceleration calculating means calculates the angular acceleration α of the rotating shaft as α = {(Ta1 × Ta2) - Ta1 2} / (Ta1 × rd) and can be calculated according to.

[0010] Moreover, the above rotation measurement system may be provided with 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. 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. Also, the positive and negative of the acceleration detected by the first acceleration sensor and the second acceleration sensor in the same circumferential direction are made equal, and the positive and negative of the acceleration detected by the third acceleration sensor and the fourth acceleration sensor in the same circumferential direction are made equal. In the adjustment amount setting means, when the angular acceleration of the rotating shaft is 0, the first adjustment amount is set 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 0. When the angular acceleration of the rotating shaft is 0, the second adjustment amount is set 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 0.

[0011] Also, 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 cylindrical shape with three or more portions having different radii about a rotation center axis. This rotation measurement system includes a sensor set corresponding to each of the three or more portions and an angular acceleration measurement means. Each of the sensor sets is fixed at positions on the outer peripheral surface of the corresponding portion that are line-symmetric with respect to the rotation center axis, and has a first acceleration sensor and a second acceleration sensor. The first acceleration sensor and the second acceleration sensor of each sensor set detect the acceleration in the tangential direction of the circle corresponding to the sensor set about the rotation center axis. Then, the angular acceleration measurement means includes, for each sensor set, a tangential acceleration calculation means for calculating the tangential acceleration at the position on the circle corresponding to the sensor set from the accelerations detected by the first acceleration sensor and the second acceleration sensor of the sensor set, and for each of two or more combinations of two of the sensor sets, an angular acceleration calculation means for obtaining a provisional angular acceleration of the rotating shaft by regarding that the difference between the two tangential accelerations is caused by the difference in the radii of the portions corresponding to the two sensor sets included in the combination, based on the two tangential accelerations calculated by the tangential acceleration calculation means for the two sensor sets included in the combination and the difference in the radii of the portions corresponding to the two sensor sets included in the combination, and an angular acceleration determination means for statistically calculating the angular acceleration of the rotating shaft from the two or more provisional angular accelerations calculated by the angular acceleration calculation means for each of the two or more combinations.

[0012] Further, in this rotation measurement system, the positive and negative of the accelerations detected by the first acceleration sensor and the second acceleration sensor of each sensor set in the same circumferential direction are made equal, and in the tangential acceleration calculation means, for each sensor set, when the acceleration detected by the first acceleration sensor of the sensor set is SA and the acceleration detected by the second acceleration sensor is SB, the tangential acceleration Ta is Ta=(SA+SB) / 2 It may be calculated according to this. Also, in this case, in the angular acceleration calculation means, for each of two or more combinations of the two sensor sets, regarding the two sensor sets included in the combination, the two tangential accelerations Ta calculated by the tangential acceleration calculation means are defined as Ta1 and Ta2, and regarding the difference in radius of the portions corresponding to the two sensor sets included in the combination as rd, the provisional angular acceleration α is α = {(Ta1 × Ta2) - Ta1 2} / (Ta1 × rd) and may be obtained according to this.

[0013] According to the rotation measurement system as described above, without requiring the exact distance from the rotation center axis to the acceleration detection point of the acceleration sensor, the angular acceleration can be accurately detected using the difference in radius between the portions of the rotating shaft where the acceleration sensors are fixed. Further, the present invention also provides a calibration system for a rotation sensor that measures the angular acceleration or angular velocity of the rotating shaft and includes the rotation measurement system. Here, the calibration system for this rotation sensor includes calibration means for calibrating the rotation sensor so that the measured value of the rotation sensor matches the angular acceleration calculated by the rotation measurement system.

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

Effects of the Invention

[0015] As described above, according to the present invention, an accurate angular acceleration can be detected without requiring the exact distance from the rotation center axis to the acceleration detection point of the acceleration sensor. Also, according to the present invention, a rotation sensor applied to the detection of the rotation of a rotating shaft can be calibrated in an actual operation state or a state similar to the actual operation.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0017] Hereinafter, a calibration system according to an embodiment of the present invention will be described. FIG. 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 rotation shaft 11 in a rotation mechanism including the rotation shaft 11, a rotation power 12, and a bearing 13 that pivotally supports the rotation shaft 11. Here, this rotation mechanism may be provided as a facility for calibrating various rotation sensors 100, or may be a facility that is actually operated in the form in which the rotation sensor 100 is applied at the site. In addition, as long as the rotation sensor 100 to be calibrated is a sensor that detects angular acceleration, the detection method thereof may be arbitrary. For example, the rotation sensor 100 may be a mechanical, optical, or vibration type angular acceleration sensor. In a rotating mechanism, the rotational power 12 is, for example, a motor or a manual flywheel, etc., and rotates the rotating shaft 11. Further, the rotating shaft 11 has a shape in which a first shaft portion 111, a second shaft portion 112, a third shaft portion 113, and a fourth shaft portion 114, each having a cylindrical or tubular shape, are arranged coaxially with the rotation center axis of the rotating shaft 11 as the center axis, and at least the second shaft portion 112 and the third shaft portion 113 have different radii.

[0018] Also, in FIG. 1, the rotation sensor 100 is shown as detecting the angular acceleration of the first shaft portion 111, but the rotation sensor 100 may detect the angular acceleration of any shaft portion. Further, the calibration system includes a first sensor set 2 including an acceleration sensor A1 and an acceleration sensor B1 fixed to the second shaft portion 112, a second sensor set 3 including an acceleration sensor A2 and an acceleration sensor B2 fixed to the third shaft portion 113, and a calibration processing device 4.

[0019] The calibration processing device 4 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 the acceleration sensor A1 and the acceleration sensor B1 of the first sensor set 2 and the acceleration sensor A2 and the acceleration sensor B2 of the second sensor set 3 as viewed in the axial direction of the rotation center axis of the rotating shaft 11. As shown in the figure, the acceleration sensor A1 and the acceleration sensor B1 of the first sensor set 2 are fixed at positions on the outer peripheral surface of the second shaft portion 112 that are line-symmetrical with respect to the rotation center axis C of the rotating shaft 11 (positions in opposite directions when viewed from the rotation center axis C). Also, the acceleration sensor A2 and the acceleration sensor B2 of the second sensor set 3 are fixed at positions on the outer peripheral surface of the third shaft portion 113 that are line-symmetrical with respect to the rotation center axis C of the rotating shaft 11 (positions in opposite directions when viewed from the rotation center axis C). Acceleration sensors A1, B1, A2, and B2 are uniaxial acceleration sensors, and as such uniaxial acceleration sensors, a capacitive MEMS sensor can be used. Here, generally, since a capacitive acceleration sensor can detect acceleration with a DC component, there is no limit to the lower limit frequency of the response. However, other types of acceleration sensors according to the measurement application may be used. For example, in applications that require the resolution of the magnitude of acceleration, a piezoelectric acceleration sensor may be used.

[0020] Also, as acceleration sensors A1, B1, A2, and B2, acceleration sensors of the same specification (same model number) are used. Therefore, the relative position / distance of the acceleration detection points of each acceleration sensor with respect to the fixed point of the acceleration sensor (the outer peripheral surface of the shaft portion) is equal.

[0021] Now, as shown in Fig. 2a, acceleration sensor A1 is arranged in a direction to detect acceleration SA1 applied in the tangential direction of a circle passing through the acceleration detection point of acceleration sensor A1 around the rotation center axis C, and acceleration sensor B1 is arranged in a direction to detect acceleration SB1 applied in the tangential direction of a circle passing through the acceleration detection point of acceleration sensor B1 around the rotation center axis C. Also, as shown by "+" for the positive direction, 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 direction of the tangent going in the same rotation direction, and they are opposite to each other when viewed from a fixed system that is fixed to the earth and does not rotate with the rotating shaft 11.

[0022] Similarly, the acceleration sensor A2 is arranged to detect the acceleration SA2 applied in the tangential direction of the circle passing through the acceleration detection point of the acceleration sensor A2 around the rotation center axis C, and the acceleration sensor B2 is arranged to detect the acceleration SB2 applied in the tangential direction of the circle passing through the acceleration detection point of the acceleration sensor B2 around the rotation center axis C. Also, as shown by "+" indicating the positive direction, the positive direction of the acceleration SA2 detected by the acceleration sensor A2 and the positive direction of the acceleration SB2 detected by the acceleration sensor B2 are set to the direction of the tangent going in the same rotation direction, and they are opposite to each other when viewed from a fixed system that is fixed to the Earth and does not rotate with the rotating shaft 11.

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

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

[0025] Now, returning to FIG. 1, the calibration target sensor angular acceleration measurement unit 41 of the calibration processing device 4 measures the angular acceleration α0 of the rotating shaft 11 with default measurement parameters from the output of the rotation sensor 100 and outputs it to the calibration unit 45. The first tangential acceleration measurement unit 42 calculates the first tangential acceleration Ta1 at a position radially distant from the rotation center axis C by a distance r1 from the accelerations SA1 and SB1 detected by the acceleration sensor A1 and the acceleration sensor B2 of the first sensor set 2. Further, the second tangential acceleration measurement unit 43 calculates a second tangential acceleration Ta2 at a position that is at a distance r2 in the radial direction from the rotation center axis C, from the accelerations SA2 and SB2 detected by the acceleration sensors A2 and B2 of the second sensor set 3. Hereinafter, the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measurement unit 42 and the calculation of the second tangential acceleration Ta2 in the second tangential acceleration measurement unit 43 will be described. First, the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measurement unit 42 will be described. FIG. 3 shows the configuration of the first tangential acceleration measurement unit 42. As shown in the figure, the first tangential acceleration measurement 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 to be equal to the gain and offset of the acceleration SB1 received by the wireless interface 421, and outputs the adjusted values 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 arithmetic processing unit 424.

[0027] The arithmetic processing unit 424 multiplies the output of the addition unit 423 by 1 / 2, and sends the result as the first tangential acceleration Ta1 to the reference angular acceleration calculation unit 44. Now, as shown in FIG. 4, let the tangential acceleration applied to acceleration sensor A1 and acceleration sensor B1 due to the angular acceleration α of the rotating shaft 11 be represented by Ta1, the gravitational acceleration be represented by g, the acceleration in the direction perpendicular to the rotation center axis C of the rotating shaft 11 applied to the rotating shaft 11 due to disturbance be represented by b, the component of the gravitational acceleration g in the positive direction of the detection axis of acceleration sensor A1 be gx, and the component of the acceleration b due to disturbance in the positive direction of the detection axis of acceleration sensor A1 be bx. Then, when viewed from the fixed system, in the state where the rotating shaft 11 has rotated by θ from the angle at which acceleration sensor A1 is located at the apex of the second shaft portion 112, the acceleration SA1 detected by acceleration sensor A1 and the acceleration SB1 detected by acceleration sensor B1 can be expressed by the following formula 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 Ta1 = (SA1 + SB1) / 2, which can be obtained.

[0029] Therefore, in the adder 423, the acceleration SA1 whose gain and offset are adjusted by the gain / offset adjustment unit 422 and the acceleration SB1 are added, and the first tangential acceleration Ta1 can be calculated by multiplying the output of the adder 423 by 1 / 2 in the arithmetic processing unit 424. Here, the adjustment amounts of the gain and offset performed by the gain / offset adjustment unit 422 will be described. Prior to the start of measurement, the operator instructs the control unit 46 to execute calibration when the angular velocity of the rotating shaft 11 is constant, preferably when the rotating shaft 11 is stationary. The control unit 46 instructed to execute calibration instructs the gain / offset adjustment unit 422 to execute the calibration operation for adjusting the gain and offset. Upon receiving the instruction, the gain / offset adjustment unit 422 executes a calibration operation and sets the adjustment values of the gain and offset applied to the acceleration SA1 such that the output of the gain / offset adjustment unit 422 and the output 0 of the adder 423, which is the addition signal of the acceleration SB1, become equal to the output of the adder 423.

[0030] Here, when the angular velocity of the rotating shaft 11 is constant or the rotating shaft 11 is in a stationary state, the angular acceleration α of the rotating shaft 11 becomes 0, the first tangential acceleration Ta1 applied to the acceleration sensor A1 and the acceleration sensor B1 becomes 0, and when the gains and offsets of the accelerations SA1 and SB1 are equal, the addition signal SA1 + SB1 is SA1 + SB1=(gx + bx)+(-gx - bx)=0.

[0031] Or, even when there is no disturbance b, SA1 + SB1=(gx)+(-gx)=0 still holds. Therefore, by setting the adjustment amounts of the gain and offset applied to the acceleration SA1 such that the addition signal output by the adder 423 becomes 0, the output of the gain / offset adjustment unit 422 can be adjusted to the signal output by the acceleration sensor A1 when the gain and offset characteristics of the acceleration sensor A1 and the acceleration detection are equal to those of the acceleration sensor B1. As a result, with the output of the gain / offset adjustment unit 422 being SA1 and the output of the second acceleration sensor being 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 measurement unit 43 is performed with the same configuration and operation as the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measurement unit 42. The description thereof is obtained by replacing the acceleration sensor A1 with the acceleration sensor A2, the acceleration sensor B1 with the acceleration sensor B2, the acceleration SA1 with the acceleration SA2, the acceleration SB1 with the acceleration SB2, and the first tangential acceleration Ta1 with the second tangential acceleration Ta2 in the description of the calculation of the first tangential acceleration Ta1 in the first tangential acceleration measurement unit 42 above.

[0033] Now, 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 difference rd in radius between the known 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 FIG. 2b, (Equation 1) r2 = r1 + rd Since the tangential acceleration = radius × angular acceleration and angular acceleration = tangential acceleration / radius, and the angular accelerations of the second shaft portion 112 and the third shaft portion 113 are the angular acceleration α of the same rotating shaft 11 and are equal, the difference between the first tangential acceleration Ta1 and the second tangential acceleration Ta2 can be regarded as being caused by the difference in radius. (Equation 2) Ta1 / r1 = Ta2 / r2 holds. Substituting Equation 1 into Equation 2, (Equation 3) Ta1 / r1 = Ta2 / (r1 + rd) is obtained.

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

[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, and correction parameters that, when applied to the angular acceleration α0, cause the corrected angular acceleration α0 to match the reference angular acceleration α. And when the rotation sensor 100 has a function of receiving the setting of the correction parameter and correcting the output according to the set correction parameter, the correction parameter calculated as the calibration information is set in the rotation sensor 100. Alternatively, when the angular acceleration measurement unit 41 of the sensor to be calibrated is also shared for angular acceleration detection using the rotation sensor 100 during actual operation, the correction parameter calculated as the calibration information is set in the angular acceleration measurement unit 41 of the sensor to be calibrated, and during actual operation, in the angular acceleration measurement unit 41 of the sensor to be calibrated, the output of the rotation sensor 100 may be corrected and used according to the set correction parameter.

[0037] Or, the calibration information may be transferred and set in a measuring device that performs angular acceleration detection using the rotation sensor 100 during actual operation, and in the measuring device, the output of the rotation sensor 100 may be corrected and used according to the correction parameter represented by the set calibration information. Now, next, the fixing of the acceleration sensors A1 and B1 to the second shaft portion 112 and the fixing of the acceleration sensors A2 and B2 to the third shaft portion 113 may be performed in any manner such as screwing, adhesion, magnetic force, winding an acceleration sensor fixing band around the shaft portion, or using other fixing tools. However, for reasons such as calibration of tangential acceleration detection, it is preferable that the acceleration sensors A1, B1, A2, and B2 are fixed in a detachable manner.

[0038] For example, as for fixing a sensor set including the acceleration sensors A and B to the shaft portion P, this fixing can be performed using the fixing tool shown in FIG. 5. FIG. 5a shows the view seen from the direction perpendicular to the rotation center axis C, FIG. 5b shows the view seen from the axial direction of the rotation center axis C, and FIG. 5c shows the perspective view. As shown in the figure, this instrument has a structure in which a first base 501 and a second base 502, each having a shape obtained by vertically dividing a cylinder with a hollow portion penetrating in the front-rear direction at the center in the vertical, horizontal, and left-right directions, are connected vertically by bolts 503. Also, as shown in Fig. 5d, this instrument arranges the separated first base 501 and second base 502 with the shaft portion P positioned therebetween, and then fastens the first base 501 and the second base 502 with bolts 503 to sandwich the shaft portion P, thereby fixing it to the shaft portion P so as to rotate together with the shaft portion P for use.

[0039] Further, when fixed to the shaft portion P, the hollow portion of this instrument has a shape in which 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 are in contact with each other at positions facing the outer peripheral surface of the shaft portion P. An acceleration sensor A is fixed to the portion of the first base 501 that contacts the outer peripheral surface of the shaft portion P, and an acceleration sensor B is fixed to the portion of the second base 502 that contacts the outer peripheral surface of the shaft portion P. The embodiments of the present invention have been described above. Here, in FIGS. 1, 2, and 4 above, the acceleration sensor A1, the acceleration sensor A2, the acceleration sensor B1, and the acceleration sensor B2 are arranged at positions where the directions viewed from the rotation center axis C are the same (positions with the same rotation phase), but these may be arranged at positions where the directions viewed from the rotation center axis C are different, for example, as shown in Fig. 6a.

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

[0041] Also, in this case, taking any combination of two sensor sets as a sensor set group, for two or more sensor set groups, perform measurement of the angular acceleration α similar to the measurement performed using the two sensor sets of the first sensor set 2 and the second sensor set 3 in the above embodiments, and obtain the final angular acceleration α by statistical processing from the angular acceleration α measured for each sensor set group. As the statistical processing, for example, a process of setting the average value of the angular acceleration α measured for each sensor set group as the final angular acceleration α can be performed. Also, the statistical processing may be a process of setting the median, the mode, or other representative values as the final angular acceleration α.

[0042] Also, in the above embodiments, the sensor set may be provided on the shaft portion where the rotation sensor 100 is disposed. Also, in the reference angular acceleration calculation unit 44 of the calibration system of the above embodiments, the measured angular acceleration α may be integrated to also measure the angular velocity ω of the rotating shaft 11. Also, in this case, the rotation sensor 100 to be calibrated may be calibrated so that the angular velocity measured by the rotation sensor 100 coincides with the angular velocity ω obtained from the angular acceleration α, with the rotation sensor 100 serving as an angular velocity sensor for detecting the angular velocity of the rotating shaft 11. Also, from the calibration system shown in the above embodiments, excluding the calibration target sensor angular acceleration measurement unit 41 and the calibration unit 45, it may be configured as a rotation measurement system that measures the angular acceleration α using sensor sets respectively arranged on shaft portions having different diameters. Also, in this case, in the rotation measurement system, the measured angular acceleration α may be integrated to also measure the angular velocity ω of the rotating shaft 11.

[0043] As described above, according to the present embodiment, it is possible to accurately detect the angular acceleration and the angular velocity based thereon from the difference in radius between the portions where the sensor set of the rotating shaft 11 is fixed without requiring the exact distance from the rotation center axis C to the acceleration detection point of the acceleration sensor. Moreover, according to the present 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 rotation shaft 11 or in a state similar to that during actual operation.

Description of Reference Numerals

[0044] 2…First sensor set, 3…Second sensor set, 4…Calibration processing device, 11…Rotation 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 rotational measurement system for measuring the angular acceleration of a rotating shaft having a first portion and a second portion, which are cylindrical or tubular shapes with different radii and centered on a rotation center axis, comprising: a first acceleration sensor and a second acceleration sensor fixed at positions on the outer peripheral surface of the first portion that are line-symmetric with respect to the rotation center axis; a third acceleration sensor and a fourth acceleration sensor fixed at positions on the outer peripheral surface of the second portion that are line-symmetric with respect to the rotation center axis; and angular acceleration measuring means; wherein the first acceleration sensor and the second acceleration sensor detect the acceleration in the tangential direction of a first circle centered on the rotation center axis, and the third acceleration sensor and the fourth acceleration sensor detect the acceleration in the tangential direction of a second circle centered on the rotation center axis; 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 by assuming that the difference between the first tangential acceleration and the second tangential acceleration is caused by the difference in the radii between the first portion and the second portion. A rotational measurement system characterized by the above.

2. The rotational measurement system according to claim 1, wherein the signs of the accelerations detected by the first acceleration sensor and the second acceleration sensor in the same circumferential direction are equal, and the signs of the accelerations detected by the third acceleration sensor and the fourth acceleration sensor in the same circumferential direction are equal; let the difference in the radii between the first portion and the second portion be rd, the acceleration detected by the first acceleration sensor be SA1, the acceleration detected by the second acceleration sensor be SB1, the acceleration detected by the third acceleration sensor be SA2, and the acceleration detected by the fourth acceleration sensor be SB2; the first tangential acceleration calculating means calculates the first tangential acceleration Ta1 as Ta1 = (SA1 + SB1) / 2 according to; the second tangential acceleration calculating means calculates the second tangential acceleration Ta2 as Ta2 = (SA2 + SB2) / 2 according to. The angular acceleration calculating means calculates the angular acceleration α of the rotating shaft α={(Ta1×Ta2)-Ta1 2} / (Ta1×rd) according to the following, and is a rotation measurement system. **Claim 3** The rotation measurement system according to claim 1, comprising a first adjustment means, a second adjustment means, and an adjustment amount setting means, wherein the signs of the accelerations detected by the first acceleration sensor and the second acceleration sensor in the same circumferential direction are equal, and the signs of the accelerations detected by the third acceleration sensor and the fourth acceleration sensor in the same circumferential direction are equal, 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 such 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 0 when the angular acceleration of the rotating shaft is 0, and sets the second adjustment amount such 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 0 when the angular acceleration of the rotating shaft is 0. The rotation measurement system is characterized by this. **Claim 4** A rotation measurement system for measuring the angular acceleration of a rotating shaft having three or more portions with different radii, which are cylindrical or cylindrical with a rotation center axis as the central axis, comprising a sensor set corresponding to each of the three or more portions, and an angular acceleration measuring means, wherein each sensor set is fixed at positions on the outer peripheral surface of the corresponding portion that are line-symmetrical with respect to the rotation center axis, and has a first acceleration sensor and a second acceleration sensor, the first acceleration sensor and the second acceleration sensor of each sensor set detect the acceleration in the tangential direction of the circle corresponding to the sensor set, with the rotation center axis as the central axis, the angular acceleration measuring means for each sensor set, a tangential acceleration calculating means for calculating the tangential acceleration at a position on the circle corresponding to the sensor set from the accelerations detected by the first acceleration sensor and the second acceleration sensor of the sensor set, For each of two or more combinations of the two sensor sets, from the two tangential accelerations calculated by the tangential acceleration calculation means for the two sensor sets included in the combination and the difference in the radii of the portions corresponding to the two sensor sets included in the combination, regarding the difference in the two tangential accelerations as being caused by the difference in the radii, angular acceleration calculation means for obtaining a provisional angular acceleration of the rotating shaft; Angular acceleration determination means for statistically calculating the angular acceleration of the rotating shaft from the two or more provisional angular accelerations calculated by the angular acceleration calculation means for each of the two or more combinations. A rotation measurement system characterized by comprising:

5. The rotation measurement system according to claim 4, The positive and negative of the accelerations detected by the first acceleration sensor and the second acceleration sensor of each sensor set in the same circumferential direction are equal, For each sensor set, the tangential acceleration calculation means designates 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, and calculates the tangential acceleration Ta as Ta = (SA + SB) / 2 According to For each of two or more combinations of the two sensor sets, regarding the two tangential accelerations Ta1 and Ta2 calculated by the tangential acceleration calculation means for the two sensor sets included in the combination as Ta1 and Ta2, and regarding the difference in the radii of the portions corresponding to the two sensor sets included in the combination as rd, the angular acceleration calculation means The provisional angular acceleration α as α={(Ta1×Ta2)-Ta1 2} / (Ta1×rd) A rotation measurement system characterized by obtaining according to.

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

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

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