Method and device for synchronous measurement of instantaneous angle and angular velocity of rotating shaft

Abstract

This invention discloses a method and apparatus for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, belonging to the field of optical measurement. The invention involves fixing an inclined plane mirror to the end face of the rotating shaft under test, and setting three measurement points on the mirror to form two mutually orthogonal measurement baselines. A laser beam is split into three probe beams to illuminate each measurement point, and the echoes are coupled to form a mixed interference signal. One optical path is equipped with an optical attenuator to generate identifiable interference components. The mixed interference signal is acquired, and multiple instantaneous frequency observations are extracted. Combining baseline parameters, mirror tilt angle, initial installation phase, and laser wavelength parameters, the instantaneous rotation angle and angular velocity at the current moment are synchronously calculated. This invention provides two sets of independent frequency observations through orthogonal dual baselines, achieving synchronous calculation at a single moment without the need for external initial values ​​or phase integration. It has advantages such as non-contact operation, high dynamics, and resistance to cumulative errors, and is suitable for non-contact dynamic measurement of rotating shafts, precision turntables, robot joints, and high-speed spindles.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement technology, specifically relating to a method and device for synchronous measurement of instantaneous angle and angular velocity of a rotating axis based on three-point orthogonal hybrid interference. It is applicable to non-contact, high-precision dynamic measurement of rotating components in precision turntables, robot joints, aerospace inertial components, and high-end CNC equipment. Background Technology

[0002] In applications such as high-end CNC machine tools, robot joints, aerospace inertial navigation, precision rotary tables, and high-speed spindle control, the accurate acquisition of instantaneous angles and angular velocities of rotating axes is a key foundation for achieving high-performance closed-loop control, fault diagnosis, and attitude perception. As equipment develops towards higher speeds, higher precision, and higher dynamic response, higher requirements are placed on the real-time performance, resolution, stability, and engineering adaptability of rotating component state measurements.

[0003] Existing methods for measuring the condition of rotating shafts mainly fall into two categories: mechanical contact and non-contact. Contact-based methods, such as encoders and tachogenerators, require direct connection to the shaft being measured, which presents challenges such as friction and wear, additional loads, high requirements for installation alignment, and limited lifespan under high-speed conditions. In non-contact methods, visual measurement is limited by camera frame rate, image processing speed, and ambient light interference, making it difficult to balance high dynamic response and high accuracy. Laser Doppler velocimetry typically outputs linear velocity information directly, requiring further conversion to angular velocity, and is prone to introducing additional errors in complex geometric scenarios.

[0004] Optical interferometry has attracted attention due to its high resolution and fast dynamic response. Constructing an interference signal by placing a tilted mirror on the end face of a rotating shaft and using the change in optical path difference from multiple measurement points is a promising non-contact measurement approach. However, in a two-point interferometry scheme, as the tilted mirror rotates with the workpiece, the rate of change of the optical path difference formed by the two measurement points depends not only on the instantaneous angular velocity of the measured shaft but also on its current rotation angle. This results in a single set of interferometric frequency observations being simultaneously affected by the coupling effect of the instantaneous rotation angle and instantaneous angular velocity, making it impossible to uniquely calculate the instantaneous state of the rotating shaft at a single moment. Such schemes typically rely on external initial values, historical phase integration, or additional reference sensors, which can easily lead to problems such as accumulated errors, unstable direction determination, and insufficient dynamic robustness.

[0005] Therefore, there is an urgent need for an optical interferometric measurement scheme that can provide two sets of independent observations at the same time to achieve synchronous measurement of the instantaneous rotation angle and instantaneous angular velocity of the rotating axis. Summary of the Invention

[0006] The purpose of this invention is to provide a method and device for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, so as to solve the technical problem that the rate of change of a single optical path difference in a dual-point interference scheme is simultaneously affected by the coupling effect of the instantaneous rotation angle and the instantaneous angular velocity, and the instantaneous rotation angle and the instantaneous angular velocity cannot be uniquely calculated.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, comprising the following steps:

[0008] S1. Fix a plane mirror on the end face of the rotating shaft to be measured, and make a preset angle between the normal of the plane mirror and the axis of the rotating shaft;

[0009] S2. Determine the first measuring point, the second measuring point, and the third measuring point on the plane mirror. The line connecting the first measuring point and the second measuring point forms the first measurement baseline, and the line connecting the second measuring point and the third measuring point forms the second measurement baseline. The first measurement baseline and the second measurement baseline are orthogonal to each other.

[0010] S3. The laser is divided into three detection optical paths, which are respectively irradiated to the first measurement point, the second measurement point and the third measurement point, and the echo signals of the three measurement points are coupled to form a mixed interference signal; wherein, an optical attenuator is set in the detection optical path corresponding to the second measurement point to generate an interference component with a distinguishable amplitude in the mixed interference signal;

[0011] S4. Acquire the mixed interference signal and perform time-frequency analysis on it to extract multiple instantaneous frequency observations of the mixed interference signal;

[0012] S5. Based on the extracted multiple instantaneous frequency observations, as well as the preset or calibrated baseline parameters, reflector tilt angle, initial installation phase, and laser wavelength parameters, simultaneously calculate the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current moment.

[0013] Furthermore, in step S1, the preset included angle is 0.2°~2°.

[0014] Further, in step S2, the length of the first measurement baseline The length of the second measurement baseline Determined based on measurement range, sensitivity, and installation space requirements.

[0015] Furthermore, in step S3, the echo signals from the three measuring points interfere with each other in pairs, and are coupled into a mixed beam by an optical fiber coupler, which is then received by a photodetector to obtain a mixed interference signal.

[0016] Furthermore, in step S3, the attenuation of the optical attenuator is 60%~90%.

[0017] Furthermore, in step S4, a short-time Fourier transform is used to perform frequency decomposition on the mixed interference signal to extract the first instantaneous frequency. Second instantaneous frequency and the third instantaneous frequency .

[0018] Furthermore, in step S5, the instantaneous angular velocity of the measured rotating shaft at the current moment is calculated by simultaneously solving the following equations. and instantaneous turning angle :

[0019]

[0020]

[0021] in, and The extracted first and second instantaneous frequencies, The length of the first measurement baseline, The length of the second measurement baseline, The wavelength of the laser. The preset tilt angle of the plane mirror. To install the initial phase.

[0022] The present invention also provides a device for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, for implementing the above method, comprising:

[0023] A plane mirror is used to fix the end face of the rotating shaft being measured, and the normal of its mirror surface forms a preset angle with the axis of the rotating shaft;

[0024] A laser source, used to emit laser light;

[0025] A 2*3 fiber optic coupler is connected to the laser source to split the laser into three detection optical paths and couple the echo signals from the three measurement points to form a mixed interference signal.

[0026] Three probe arms are connected to 2*3 fiber optic couplers respectively, and are used to illuminate the first, second and third measurement points on the plane mirror with three probe beams, and to receive the echo signals from the three measurement points; wherein, the probe arm corresponding to the second measurement point is equipped with an optical attenuator at the front end, which is used to generate an interference component with identifiable amplitude in the mixed interference signal;

[0027] The probe arm fixing assembly is used to position and fix the three probe arms according to the three determined measuring points, so that the three probe arms are facing the three measuring points.

[0028] A photodetector, connected to a 2x3 fiber optic coupler, is used to acquire mixed interference signals;

[0029] A computer, connected to a photodetector, is used to perform time-frequency analysis on the received mixed interference signal, extract multiple instantaneous frequency observations of the mixed interference signal, and simultaneously calculate the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current moment based on the extracted multiple instantaneous frequency observations and the preset or calibrated baseline parameters, reflector tilt angle, initial installation phase and laser wavelength parameters.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention constructs three measuring points on a reflector and forms two sets of independent interference frequency observations by two mutually orthogonal measurement baselines. This transforms the problem in the dual-measuring-point scheme where a single set of observations is simultaneously affected by the coupling of instantaneous rotation angle and instantaneous angular velocity and cannot be uniquely calculated at a single moment into a problem where instantaneous rotation angle and instantaneous angular velocity can be calculated simultaneously, thereby improving the identifiability and reliability of the measurement results.

[0032] 2. This invention does not require external initial values, long-term phase integration, or additional reference sensors. It can directly calculate the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current sampling moment based on multiple instantaneous frequency observations and system calibration parameters. Therefore, it has good real-time performance and is suitable for dynamic state perception and closed-loop control scenarios.

[0033] 3. This invention uses laser interferometry and photoelectric detection, which involves no mechanical contact and no wear. The dynamic response of the system is mainly limited by the photoelectric detection bandwidth and signal processing speed, making it suitable for high-speed rotating scenarios.

[0034] 4. This invention solves the problem by combining two sets of independent observations, which can reduce the impact of single-channel integral drift, phase unwrapping jump, and unstable direction discrimination on the final result, and has strong resistance to cumulative error.

[0035] 5. This invention, by setting an optical attenuator in the optical path of the set measurement point, makes the target frequency component in the mixed interference signal have identifiable differences in amplitude, thereby facilitating the corresponding identification of multiple instantaneous frequency observations and improving the stability and engineering usability of subsequent synchronous calculations. Attached Figure Description

[0036] Figure 1 A schematic diagram of the overall structure of the synchronous measurement device for instantaneous angle and angular velocity of a rotating shaft provided in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the principle of tilting the plane mirror and orthogonally arranging the three measuring points and double baselines in an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the time-domain waveform of the hybrid interference signal in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the instantaneous frequency calculation results of the hybrid interference signal in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram illustrating the instantaneous frequency change of the hybrid interference signal over time in an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the instantaneous rotation angle measurement results in an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the instantaneous angular velocity measurement results in an embodiment of the present invention.

[0043] In the diagram: 1-Base; 2-Probe arm holder; 3-Probe arm 1; 4-Probe arm 2; 5-Probe arm 3; 6-2*3 fiber optic coupler; 7-Photodetector; 8-Laser source; 9-Plane mirror; 10-Adhesive; 11-Measured rotating shaft; 12-Optical attenuator; 13-Computer. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] like Figure 1 As shown, this embodiment provides a device for synchronously measuring the instantaneous angle and angular velocity of a rotating axis, including a plane mirror 9, a laser source 8, a 2*3 fiber optic coupler 6, three probe arms 3~5, a probe arm fixing assembly, a photodetector 7, and a computer 13.

[0048] The planar reflector 9 is fixed to the end face of the rotating shaft 11 under test by adhesive 10, and its mirror normal forms a preset angle with the axis of the rotating shaft. A laser source 8 emits laser light. A 2*3 fiber optic coupler 6 is connected to the laser source 8 to split the laser into three probe light paths and couple the echo signals from the three measurement points to form a mixed interference signal. Three probe arms 3, 4, and 5 are connected to the 2*3 fiber optic coupler 6 to illuminate the three probe lights onto the first, second, and third measurement points on the planar reflector and to receive the echo signals from the three measurement points. The probe arm corresponding to the second measurement point has an optical attenuator 12 at its front end to generate an interference component with identifiable amplitude in the mixed interference signal, assisting in the identification of instantaneous frequency measurements. The probe arm fixing assembly consists of a base 1 and a probe arm fixing frame 2, used to position and fix the three probe arms according to the determined three measurement points, ensuring that the three probe arms are directly facing the three measurement points. The photodetector 7 is connected to the 2*3 fiber optic coupler 6 for acquiring the mixed interference signal. The computer 13 is connected to the photodetector 7 for performing time-frequency analysis on the received mixed interference signal, extracting multiple instantaneous frequency observations of the mixed interference signal, and simultaneously calculating the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current moment based on the extracted multiple instantaneous frequency observations and the preset or calibrated baseline parameters, reflector tilt angle, initial installation phase, and laser wavelength parameters.

[0049] Based on the above-mentioned device, this embodiment provides a method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, the implementation steps of which are as follows.

[0050] S1. Fix a plane mirror on the end face of the rotating shaft to be measured, and make the normal of the plane mirror form a preset angle with the axis of the rotating shaft.

[0051] S2. Determine a first measuring point, a second measuring point, and a third measuring point on the plane mirror. The line connecting the first measuring point and the second measuring point forms a first measurement baseline, and the line connecting the second measuring point and the third measuring point forms a second measurement baseline. The first measurement baseline and the second measurement baseline are orthogonal to each other.

[0052] S3. The laser is split into three detection optical paths, which are respectively irradiated to the first, second, and third measurement points. The echo signals from the three measurement points are coupled to form a mixed interference signal. An optical attenuator is placed in the detection optical path corresponding to the second measurement point to generate an interference component with a distinguishable amplitude in the mixed interference signal.

[0053] S4. Acquire the mixed interference signal and perform time-frequency analysis on it to extract multiple instantaneous frequency observations of the mixed interference signal.

[0054] S5. Based on the extracted multiple instantaneous frequency observations (first instantaneous frequency) Second instantaneous frequency Third instantaneous frequency The system simultaneously calculates the instantaneous rotation angle of the measured rotating shaft at the current moment, along with preset or calibrated baseline parameters, mirror tilt angle, initial installation phase, and laser wavelength parameters. and instantaneous angular velocity .

[0055] In this embodiment, the object being measured is a rotating shaft. A plane mirror is fixed to the end face of the rotating shaft. The plane mirror can be a metal mirror or a plane mirror with a reflective coating, and a preset angle α is set between the mirror surface normal and the axis of the rotating shaft. Preferably, the preset angle is 0.2°~2°. In this embodiment, we take... The purpose of setting this preset angle is that, as the rotation axis rotates, the optical path length of different measuring points on the surface of the reflector relative to the probe optical path changes periodically with the rotation angle, thus providing a basis for the formation of subsequent interference signals.

[0056] like Figure 2 As shown, a first measuring point P1, a second measuring point P2, and a third measuring point P3 are set on the surface of the reflector. The first measuring point P1 and the second measuring point P2 form a first measurement baseline, and the second measuring point P2 and the third measuring point P3 form a second measurement baseline. The first and second measurement baselines are orthogonal to each other. The length of the first measurement baseline is denoted as […]. The length of the second measurement baseline is denoted as The baseline length can be preset according to the measurement range, sensitivity, and installation space requirements. From the perspective of measurement range and sensitivity, the longer the baseline length, the better; from the perspective of installation space, a baseline that is too long may cause the light spot at the measuring point to fall outside the plane mirror, resulting in measurement failure, while a baseline that is too short may prevent the probe arm barrel from being installed. Therefore, the baseline length should preferably be 0.8 to 1.2 times the radius of the mirror. In this embodiment, the diameter of the plane mirror is approximately 25 mm, so the baseline length is... , .

[0057] The three detection components correspond to three measurement points P1, P2, and P3, respectively. Each detection component can employ a fiber optic probe with a collimating lens or a spherical lens to ensure stable illumination of the corresponding measurement point by the detection light and improve echo coupling efficiency. The laser source is preferably a narrow-linewidth single-frequency laser. In this embodiment, the laser wavelength is 1550 nm. The echo signals from the three measurement points interfere pairwise and are coupled into a single mixed interference signal via fiber optic coupler 6, which is then acquired by a single high-speed photodetector 7. In this embodiment, the sampling rate of the photodetector is 10 MHz. Using a single detector simplifies the system structure and improves system compactness.

[0058] Short-time Fourier transform is used to perform frequency decomposition on the mixed interference signal, extracting multiple instantaneous frequency observations of the mixed interference signal, including the first instantaneous frequency. Second instantaneous frequency and the third instantaneous frequency .

[0059] Since the mixed interference signal is a real signal, it is difficult to directly distinguish the correspondence between the instantaneous frequency components based solely on frequency values. To facilitate the differentiation of different frequency components in the mixed interference signal, this method sets an optical attenuator in the probe optical path corresponding to the second measurement point P2 to change the amplitude distribution of the relevant interference components, thereby determining the second measurement point. The method then uses the spectral amplitude characteristics to determine the first instantaneous frequency... Second instantaneous frequency and the third instantaneous frequency The attenuation of the optical attenuator is preferably 60% to 90%. By setting the optical attenuator, a specific combination of frequency components can be made to have a significant difference in spectral amplitude relative to other frequency components, thereby facilitating the subsequent data processing unit to identify the corresponding instantaneous frequency observations.

[0060] When the rotating shaft rotates, the reflector has a preset tilt angle relative to the axis. The optical path lengths of the three measuring points P1, P2, and P3 relative to their respective probe optical paths change with the rotation angle of the axis. When the first and second measuring baselines are arranged along two orthogonal directions of the mirror coordinate system, and the initial phase is... The optical path difference between the three measurement points satisfies the following relationship:

[0061]

[0062]

[0063]

[0064] in, This represents the optical path difference corresponding to the first measurement baseline. This indicates the optical path difference corresponding to the second measurement baseline. Indicates the combined optical path difference. Indicates the rotation axis at time [time]. The instantaneous turning angle.

[0065] Based on the aforementioned optical path difference relationship, the mixed interference signal formed by the echoes from the three measurement points can be expressed as the superposition of three sets of interference terms. Its time-domain signal is as follows: Figure 3 As shown. Figure 3The mixed interference waveform that varies with time is shown. It can be seen that the signal contains multiple modulation components of different frequencies, indicating that multiple sets of effective interference information are formed between the echoes from the three measurement points.

[0066] The time-domain expression for the hybrid interference signal is:

[0067]

[0068] in, , , These represent the light intensities corresponding to the three detection optical paths. is the laser wavelength.

[0069] Furthermore, on Figure 3 The time-domain interferometric signal shown can be analyzed in time and frequency to obtain its frequency domain characteristics, such as... Figure 4 As shown. Preferably, the data processing unit uses short-time Fourier transform to process the acquired mixed interference signal to extract three main instantaneous frequency components, denoted as follows: , and Since the mixed interference signal is a real signal, it is difficult to directly determine the correspondence between each frequency component and each optical path difference based solely on the frequency value. Therefore, this embodiment utilizes an optical attenuator placed in the optical path corresponding to the second measurement point P2 to make one of the combined frequency components significantly different in amplitude from the other two frequency components, thereby completing the... , and The identification results are as follows Figure 5 As shown.

[0070] Three instantaneous frequency components (first instantaneous frequency) Second instantaneous frequency and the third instantaneous frequency The following relationship is satisfied:

[0071]

[0072]

[0073]

[0074] And there are:

[0075]

[0076] Due to the parameters already installed in the system , , All are known, and the initial phase of installation is... This can be obtained through calibration after rotating the axis one revolution; therefore, it can be obtained from... and Solve simultaneously for the instantaneous angular velocity of the axis of rotation at the current moment. and instantaneous turning angle Specifically, the following relationship can be used for calculation:

[0077]

[0078]

[0079] in, and The extracted first and second instantaneous frequencies, The length of the first measurement baseline, The length of the second measurement baseline, The wavelength of the laser. The preset tilt angle of the plane mirror. To install the initial phase.

[0080] The above calculation method can simultaneously obtain the instantaneous rotation angle and instantaneous angular velocity of the rotation axis at a single sampling moment, without relying on long-term integration of a single frequency observation, external reference angle sensor, or historical trajectory extrapolation.

[0081] Figure 6 The measurement results of the instantaneous rotation angle in this embodiment are shown. From Figure 5 It can be seen that the instantaneous rotation angle results obtained by the method of the present invention can continuously reflect the angular position changes of the rotation axis, and have good real-time performance and stability. Figure 7 The measurement results of the instantaneous angular velocity in this embodiment are shown. From Figure 6 It can be seen that the measured instantaneous angular velocity can accurately track the speed change process of the measured rotating shaft, and is suitable for dynamic measurement under conditions such as steady speed, speed change and reversal.

[0082] Compared with existing dual-point interferometry schemes, this invention constructs two mutually orthogonal measurement baselines through three measurement points and extracts two sets of independent frequency observations from the mixed interferometric signal, realizing the synchronous calculation of the instantaneous rotation angle and instantaneous angular velocity of the rotating shaft. This avoids the problem that a single set of observations cannot be uniquely calculated due to the simultaneous coupling effect of instantaneous rotation angle and instantaneous angular velocity. It has better identifiability, resistance to cumulative error, and engineering application value.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, characterized in that, Includes the following steps: S1. Fix a plane mirror on the end face of the rotating shaft to be measured, and make a preset angle between the normal of the plane mirror and the axis of the rotating shaft; S2. Determine the first measuring point, the second measuring point, and the third measuring point on the plane mirror. The line connecting the first measuring point and the second measuring point forms the first measurement baseline, and the line connecting the second measuring point and the third measuring point forms the second measurement baseline. The first measurement baseline and the second measurement baseline are orthogonal to each other. S3. The laser is divided into three detection optical paths, which are respectively irradiated to the first measurement point, the second measurement point and the third measurement point, and the echo signals of the three measurement points are coupled to form a mixed interference signal; wherein, an optical attenuator is set in the detection optical path corresponding to the second measurement point to generate an interference component with a distinguishable amplitude in the mixed interference signal; S4. Acquire the mixed interference signal and perform time-frequency analysis on it to extract multiple instantaneous frequency observations of the mixed interference signal; S5. Based on the extracted multiple instantaneous frequency observations, as well as the preset or calibrated baseline parameters, reflector tilt angle, initial installation phase, and laser wavelength parameters, simultaneously calculate the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current moment.

2. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S1, the preset included angle is 0.2°~2°.

3. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S2, the length of the first measurement baseline The length of the second measurement baseline Determined based on measurement range, sensitivity, and installation space requirements.

4. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S3, the echo signals from the three measuring points interfere with each other in pairs, and are coupled into a mixed beam by an optical fiber coupler, which is then received by a photodetector to obtain a mixed interference signal.

5. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S3, the attenuation of the optical attenuator is 60%~90%.

6. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S4, the short-time Fourier transform is used to perform frequency decomposition on the mixed interference signal to extract the first instantaneous frequency. Second instantaneous frequency and the third instantaneous frequency .

7. The method for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft according to claim 1, characterized in that, In step S5, the instantaneous angular velocity of the measured rotating shaft at the current moment is calculated by simultaneously solving the following equations. and instantaneous turning angle : in, and The extracted first and second instantaneous frequencies, The length of the first measurement baseline, The length of the second measurement baseline, The wavelength of the laser. The preset tilt angle of the plane mirror. To install the initial phase.

8. A device for synchronously measuring the instantaneous angle and angular velocity of a rotating shaft, used to implement the method as described in any one of claims 1-7, characterized in that, include: A plane mirror is used to fix the end face of the rotating shaft being measured, and the normal of its mirror surface forms a preset angle with the axis of the rotating shaft; A laser source, used to emit laser light; A 2*3 fiber optic coupler is connected to the laser source to split the laser into three detection optical paths and couple the echo signals from the three measurement points to form a mixed interference signal. Three probe arms are connected to 2*3 fiber optic couplers respectively, and are used to illuminate the first, second and third measurement points on the plane mirror with three probe beams, and to receive the echo signals from the three measurement points; wherein, the probe arm corresponding to the second measurement point is equipped with an optical attenuator at the front end, which is used to generate an interference component with identifiable amplitude in the mixed interference signal; The probe arm fixing assembly is used to position and fix the three probe arms according to the three determined measuring points, so that the three probe arms are facing the three measuring points. A photodetector, connected to a 2x3 fiber optic coupler, is used to acquire mixed interference signals; A computer, connected to a photodetector, is used to perform time-frequency analysis on the received mixed interference signal, extract multiple instantaneous frequency observations of the mixed interference signal, and simultaneously calculate the instantaneous rotation angle and instantaneous angular velocity of the measured rotating shaft at the current moment based on the extracted multiple instantaneous frequency observations and the preset or calibrated baseline parameters, reflector tilt angle, initial installation phase and laser wavelength parameters.

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