A multi-point synchronous vibration measurement method and device based on laser triangulation principle

Abstract

The present invention discloses a multi-point synchronous vibration measurement method and device based on the principle of laser triangulation. The present invention is based on the principle of laser triangulation displacement measurement. By emitting a laser to illuminate the vibrating object, and then using a linear array photoelectric sensor to perform real-time spot position detection, the high-speed displacement is calculated to measure and achieve distance measurement. The method uses an external unified synchronous clock signal source to achieve scalable and low-cost multi-point synchronous vibration measurement, providing an effective means to solve the multi-point synchronous vibration measurement requirements in scenarios such as aircraft engine vibration detection. The purpose of the present invention is to provide a low-cost multi-point, synchronous, non-contact vibration measurement method. The method is based on the principle of laser triangulation to achieve distance measurement. It adopts a modular design and can easily increase the number of measurement positions by adding probes. It has good scalability and integration and can achieve synchronous measurement of multi-point vibration.

Description

Technical Field

[0001] The present invention relates to the field of vibration measurement technology, and in particular to a multi-point synchronous vibration measurement method and device based on the laser triangulation principle. Background Art

[0002] Vibration frequency is an important parameter that reflects the structural and defect characteristics of an object. Taking aircraft engines as an example, during their development, manufacturing, and service, it is necessary to ensure that the engine can operate reliably under harsh operating conditions such as high temperature, high pressure, and high speed. However, due to the coupling of multiple fields such as aerodynamic fields, inertial force fields, and mechanical vibration fields, the engine's blades, casings, pipes, gears, and other structural components are at risk of affecting the efficiency of the power equipment due to excessive vibration. In severe cases, the aircraft engine may experience rotor-stator rubbing, excessive instantaneous bearing loads, and excessive component vibration stress, endangering flight safety and even leading to catastrophic accidents. Therefore, to ensure the safe operation of aircraft engines, vibration measurement and vibration fatigue testing of key engine parts are required, such as high- and low-frequency vibration fatigue testing of engine blades in high-temperature environments.

[0003] Currently, non-contact vibration measurement mostly uses laser Doppler vibrometer technology, such as Polytec's laser vibrometers. These instruments offer high measurement accuracy, but their high cost and bulk limit their application in multi-point vibration measurement scenarios. Furthermore, multi-point vibration measurement requires high synchronization performance, and synchronization between multiple independent vibrometers is also a key issue that needs to be addressed. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-cost multi-point, synchronous non-contact vibration measurement method. The method realizes distance measurement based on the principle of laser triangulation and adopts a modular design. The number of measurement positions can be easily increased by adding probes. It has good scalability and integration and can realize synchronous measurement of multi-point vibration.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-point synchronous vibration measuring device based on the laser triangulation principle comprises a vibration measuring probe housing (1), a microcontroller (2), a laser emitter (3), a measuring laser (4), a vibration range of a measured object (5), an actual displacement waveform (6), a vibration limit position I (7), a measured object (8), a vibration limit position II (9), a return laser (10), a focusing lens group (11), a linear array photoelectric sensor (12), a focus light point movement range (13), a voltage signal waveform (14), a synchronous clock signal source (15), a probe I microcontroller (16), Vibration measuring probe I (17), measuring laser I (18), return laser I (19), probe II microcontroller (20), vibration measuring probe II (21), measuring laser II (22), return laser II (23), multi-point measured object (24), probe III microcontroller (25), vibration measuring probe III (26), measuring laser III (27), return laser III (28), data acquisition card (29), amplitude-frequency analysis algorithm module (30), amplitude-frequency information (31), vibration measuring point I (32), vibration measuring point II (33), vibration measuring point III (34).

[0007] The microcontroller (2), laser emitter (3), focusing lens group (11), and linear array photoelectric sensor (12) are all fixed in the vibration measuring probe housing (1). The microcontroller (2) controls the laser emitter (3) to emit a measuring laser (4) to irradiate the surface of the object to be measured (8). After diffuse reflection, a return laser (10) is formed and focused on the linear array photoelectric sensor (12) through the focusing lens group (11). The linear array photoelectric sensor (12) converts the return laser (10) into a voltage signal, which is then output by the microcontroller (2) to achieve position measurement. When the object to be measured (8) vibrates between the vibration limit position I (7) and the vibration limit position II (9) with an actual displacement waveform (6), the return laser (10) forms a focused light spot moving interval (13) on the linear array photoelectric sensor (12) and generates a voltage signal waveform (14) which is output to the data acquisition card (29). After passing through the amplitude-frequency analysis algorithm module (30), the amplitude-frequency information (31) is obtained, thereby completing the measurement.

[0008] The specific implementation process of the multi-point synchronous vibration measurement method based on the laser triangulation principle is as follows:

[0009] When the object to be measured (8) is at any position between the vibration limit displacement I (7) and the vibration limit position II (9), the return laser (10) will form a unique focused light spot on the photosensitive belt of the linear array photoelectric sensor (12) after passing through the focusing lens group (11). The position of the focused light spot is in a one-to-one mapping relationship with the position of the object to be measured (8), which can be described by the following high-order polynomial:

[0010]

[0011] Among them, Ptarget is the position of the object being measured (8), P sensor is the position of the focused spot formed by the reflected laser (10) on the linear array photoelectric sensor (12), k is the highest order of the polynomial, which can usually be 10 to 15, and A i In actual measurement, the microcontroller (2) can calculate the position P of the light spot formed by the returning laser (10) on the surface of the linear array photoelectric sensor (12) based on the polynomial. sensor When the object (8) is measured, its actual spatial position is obtained to achieve real-time position calculation.

[0012] The multi-point synchronous vibration measurement method based on the laser triangulation principle can be used to arrange vibration measuring probes at different points of the multi-point object (24) where vibration measurement is required. Without loss of generality, a three-point measurement is taken as an example. On the surface of the multi-point object (24), there are three positions where synchronous vibration measurement is required, namely, vibration measuring point I (32), vibration measuring point II (33), and vibration measuring point III (34). The vibration measuring head I (17) emits a measuring laser I (18) which is irradiated to the vibration measuring point I (32) and forms a return laser I (19) after diffuse reflection for measurement. The vibration measuring head II (21) emits a measuring laser II (22) which is irradiated to the vibration measuring point II (33) and forms a return laser II (23) after diffuse reflection for measurement. The vibration measuring head III (26) emits a measuring laser III (27) which is irradiated to the vibration measuring point III (34) and forms a return laser III (28) after diffuse reflection for measurement. During the measurement process, the synchronous clock signal source (15) sends a synchronous acquisition signal in real time to the probe I microcontroller (16), the probe II microcontroller (20), and the probe III microcontroller (25) for synchronous measurement, and synchronously outputs an analog voltage signal to the data acquisition card (29) for acquisition, thereby achieving synchronous vibration measurement at three points. Similarly, for synchronous vibration measurement at more points, it is only necessary to add probes at the required measurement locations.

[0013] The multi-point synchronous vibration measurement method based on the triangular laser principle is specifically that the synchronous acquisition signal output by the synchronous clock signal source (15) has a fixed frequency f s The signals include but are not limited to discrete pulse sequences, rising and falling edges of square waves, etc. Each time the vibration probe I (17), vibration probe II (21) and vibration probe III (26) receive a synchronous acquisition signal, they collect a set of data and transmit it to the data acquisition card (29). Therefore, the effective sampling frequency of the data acquisition card (29) is also f s The sampling frequency f s It should be at least twice the vibration frequency f of the multi-point measured object (24) that needs to be measured.

[0014] The amplitude-frequency analysis algorithm module accepts input displacement data represented as a discrete time sequence X[t]. The module includes a sliding buffer of selectable length n. Whenever new data is collected, it is sequentially added to the sliding buffer. When the sliding buffer is full, each new data entry clears the oldest data in the buffer, ensuring that the maximum number of sliding buffers is n.

[0015] The amplitude-frequency analysis algorithm module will rapidly change all the data in the sliding buffer in real time to extract spectrum information. The specific transformation equation is as follows:

[0016]

[0017] Through the above transformation, the spectrum information of the measured displacement sequence is extracted and the spectrum measurement is completed.

[0018] The beneficial effects of the present invention are as follows:

[0019] This method, based on the principle of laser triangulation displacement measurement, irradiates a vibrating object with laser light and uses a linear array photoelectric sensor to detect the spot position in real time, calculating high-speed displacement for distance measurement. This method utilizes an external, unified, synchronous clock signal source to achieve scalable, low-cost, multi-point synchronous vibration measurement, providing an effective means for addressing multi-point synchronous vibration measurement requirements in scenarios such as aircraft engine vibration testing.

[0020] The purpose of the present invention is to provide a low-cost multi-point, synchronous non-contact vibration measurement method. The method realizes distance measurement based on the principle of laser triangulation and adopts a modular design. The number of measurement positions can be easily increased by adding probes. It has good scalability and integration and can realize synchronous measurement of multi-point vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a vibration measurement principle based on the laser triangulation principle;

[0022] Figure 2 This is a schematic diagram of a multi-point synchronous vibration measurement method and device;

[0023] Figure 3 The overall process of vibration measurement;

[0024] Figure 4 The workflow of the spectrum analysis algorithm module;

[0025] Figure 5 This is a schematic diagram of the working principle of the sliding buffer zone. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] like Figure 1 As shown, the microcontroller (2), laser emitter (3), focusing lens group (11), and linear array photoelectric sensor (12) are all fixed in the vibration measuring probe housing (1). The microcontroller (2) controls the laser emitter (3) to emit a measuring laser (4) to irradiate the surface of the object to be measured (8). After diffuse reflection, the returning laser (10) is formed and focused on the linear array photoelectric sensor (12) through the focusing lens group (11). The linear array photoelectric sensor (12) converts the returning laser (10) into a voltage signal, which is then output by the microcontroller (2) to achieve position measurement. When the object to be measured (8) vibrates between the vibration limit position I (7) and the vibration limit position II (9) with the actual displacement waveform (6), the returning laser (10) forms a focused light spot moving interval (13) on the linear array photoelectric sensor (12) and generates a voltage signal waveform (14).

[0028] like Figure 2 As shown, on the surface of the multi-point measured object (24), there are three locations that need synchronous vibration measurement, namely vibration measurement point I (32), vibration measurement point II (33) and vibration measurement point III (34). The vibration probe I (17) emits measurement laser I (18) to irradiate the vibration measurement point I (32). After diffuse reflection, it forms return laser I (19) for measurement. The vibration probe II (21) emits measurement laser II (22) to irradiate the vibration measurement point II (33). After diffuse reflection, it forms return laser II (23) for measurement. The vibration probe III (26) emits measurement laser III (27) to irradiate the vibration measurement point III (34). After diffuse reflection, it forms return laser III (28) for measurement. During the measurement process, the synchronous clock signal source (15) sends a synchronous acquisition signal in real time to the probe I microcontroller (16), the probe II microcontroller (20) and the probe III microcontroller (25) for synchronous measurement, and synchronously outputs an analog voltage signal to the data acquisition card (29) for acquisition, thereby realizing synchronous vibration measurement of the three points. Similarly, for synchronous vibration measurement of more points, it is only necessary to add probes at the required measurement locations.

[0029] like Figure 3 As shown, a multi-point synchronous vibration measurement method based on the laser triangulation principle specifically includes the following steps:

[0030] Step 1. The vibration probe emits a measuring laser onto the surface of the object being measured. After diffuse reflection from the surface of the object, the return laser carrying position information is returned to the linear array photoelectric sensor.

[0031] Step 2. The linear array photoelectric sensor extracts the spot position formed by the returning laser and linearizes it using a high-order polynomial model. The position information is converted into an analog voltage signal and transmitted to the data acquisition card.

[0032] Step 3. The data acquisition card converts the analog voltage signal into a digital displacement signal through high-speed analog-to-digital conversion to obtain the vibration amplitude information of the original displacement, and transmits the converted digital displacement signal to the amplitude-frequency analysis algorithm module;

[0033] Step 4. The amplitude-frequency analysis algorithm module converts the displacement data into spectrum data through a fast spectrum analysis algorithm, extracts the vibration spectrum of the object under test, and obtains spectrum information;

[0034] Step 5. Integrate the vibration amplitude information and vibration spectrum information of the object under test to obtain the final amplitude-frequency spectrum information, and complete the multi-point vibration amplitude-frequency synchronous measurement.

[0035] like Figure 4 As shown, the amplitude-frequency analysis algorithm module includes the following steps:

[0036] Step (1). The original data is input into the data buffer for caching;

[0037] Step (2) determines whether filtering is required. If filtering is required, the data in the buffer is input into the filter, and after passing through a low-pass, high-pass, band-pass or band-stop filter, the filtered data is filled into the calculation buffer; if filtering is not required, the data in the data buffer is directly filled into the calculation buffer;

[0038] Step (3). Determine whether the calculation buffer is full. If not, it indicates that the spectrum is not ready and waits. When the calculation buffer is full, perform fast Fourier transform and calculate the spectrum amplitude, filter out the DC component, and finally obtain the output spectrum information to complete the spectrum processing.

[0039] like Figure 5 As shown, the sliding buffer adopts the form of a sliding window, and the window width of the sliding window is a power of 2. Without loss of generality, taking a sliding window with a window width of 8 as an example, when the sliding window of the previous frame is filled with the 2nd to 9th data in the figure, when new data 10 enters, the first-entered data 2 will be moved out of the sliding window and the new data 10 will be added to the sliding window. In this way, first-in-first-out sliding data extraction can be achieved. Whenever new data enters, the sliding window will be updated and the data in the sliding window will be transformed to achieve the extraction and solution of spectral information.

Claims

1. A multi-point synchronous vibration measurement device based on the laser triangulation principle, characterized in that The invention comprises a vibration measuring probe housing (1), a microcontroller (2), a laser transmitter (3), a measuring laser (4), a vibration range of a measured object (5), an actual displacement waveform (6), a vibration limit position I (7), a measured object (8), a vibration limit position II (9), a return laser (10), a focusing lens group (11), a linear array photoelectric sensor (12), a focus light spot moving range (13), a voltage signal waveform (14), a synchronous clock signal source (15), a microcontroller of the probe I (16), a vibration measuring probe I (17), Measuring laser I (18), returning laser I (19), probe II microcontroller (20), vibration measuring probe II (21), measuring laser II (22), returning laser II (23), multi-point measured object (24), probe III microcontroller (25), vibration measuring probe III (26), measuring laser III (27), returning laser III (28), data acquisition card (29), amplitude-frequency analysis algorithm module (30), amplitude-frequency information (31), vibration measuring point I (32), vibration measuring point II (33), vibration measuring point III (34); The microcontroller (2), the laser emitter (3), the focusing lens group (11), and the linear array photoelectric sensor (12) are all fixed in the vibration measuring probe housing (1). The microcontroller (2) controls the laser emitter (3) to emit a measuring laser (4) to irradiate the surface of the object to be measured (8). After diffuse reflection, a return laser (10) is formed and focused on the linear array photoelectric sensor (12) through the focusing lens group (11). The linear array photoelectric sensor (12) converts the return laser (10) into a voltage signal, which is then output by the microcontroller (2) to achieve position measurement. When the object to be measured (8) vibrates with an actual displacement waveform (6) between the vibration limit position I (7) and the vibration limit position II (9), the return laser (10) forms a focused light spot moving interval (13) on the linear array photoelectric sensor (12) and generates a voltage signal waveform (14) which is output to the data acquisition card (29). After passing through the amplitude-frequency analysis algorithm module (30), the amplitude-frequency information (31) is obtained, thereby completing the measurement. When the object to be measured (8) is at any position between the vibration limit position I (7) and the vibration limit position II (9), the return laser (10) will form a unique focused light spot on the photosensitive belt of the linear array photoelectric sensor (12) after passing through the focusing lens group (11). The position of the focused light spot is in a one-to-one mapping relationship with the position of the object to be measured (8), which is described by the following high-order polynomial: Among them, P target is the position of the object being measured (8), P sensor is the focus spot position formed by the reflected laser (10) on the linear array photoelectric sensor (12), k is the highest order of the polynomial, ranging from 10 to 15, A i are the coefficients of the polynomial; in actual measurement, the microcontroller (2) can calculate the position P of the light spot formed by the returning laser (10) on the surface of the linear array photoelectric sensor (12) according to the polynomial. sensor When the object (8) is measured, the actual spatial position of the object (8) is obtained to achieve real-time position calculation; When multi-point vibration measurement is performed based on the device, vibration measuring probes can be arranged at different points of the multi-point object (24) where vibration measurement is required; there are three positions on the surface of the multi-point object (24) where vibration measurement needs to be measured synchronously, namely, vibration measuring point I (32), vibration measuring point II (33) and vibration measuring point III (34); the vibration measuring probe I (17) emits measuring laser I (18) to irradiate the vibration measuring point I (32) and forms return laser I (19) after diffuse reflection for measurement; the vibration measuring probe II (21) emits measuring laser II (22) to irradiate the vibration measuring point II (33) ) forms a return laser II (23) for measurement after diffuse reflection, and the vibration measuring probe III (26) emits a measuring laser III (27) to irradiate the vibration measuring point III (34) and forms a return laser III (28) for measurement after diffuse reflection; during the measurement process, the synchronous clock signal source (15) sends a synchronous acquisition signal in real time to the probe I microcontroller (16), the probe II microcontroller (20), and the probe III microcontroller (25) for synchronous measurement, and synchronously outputs an analog voltage signal to the data acquisition card (29) for acquisition, thereby realizing synchronous vibration measurement of the three points; The synchronous acquisition signal output by the synchronous clock signal source (15) has a fixed frequency f s The vibration measuring head I (17), the vibration measuring head II (21) and the vibration measuring head III (26) collect a set of data and transmit it to the data acquisition card (29) every time they receive a synchronous acquisition signal. Therefore, the effective sampling frequency of the data acquisition card (29) is also f s ; The sampling frequency f used s It should be at least twice the vibration frequency f of the multi-point measured object (24) that needs to be measured; The implementation of the amplitude-frequency analysis algorithm module is as follows: the input displacement data can be expressed as a discrete time sequence X[t], and the module has a sliding buffer with an optional length n; whenever new data is collected, the new data will be added to the sliding buffer in sequence. When the sliding buffer is full, the data that entered the buffer first will be cleared when a new data enters, ensuring that the maximum number of sliding buffers is n; the algorithm analysis module will quickly change all the data in the sliding buffer in real time to extract the spectrum information Y j , the specific transformation equation is as follows: Wherein, j is an integer.

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