A method for measuring the synchronization phase difference of a multi-machine drive system by using a high-speed camera

Abstract

The application discloses a kind of high-speed camera detection multi-machine drive system synchronous phase difference measurement method, it is related to vibrating screen synchronous detection technical field, and the device used includes vibrating screen prototype, high-speed camera, camera support, data processing software and positioning sheet etc..First, high-speed camera is installed with the plane parallel of vibrating screen motor rotor, and image sequence in the rotating process of rotor is collected;Second, the pixel coordinates of positioning sheet and rotating center are obtained by image recognition technology, and relative position vector is constructed. Through interpolation noise reduction processing to vector coordinates, project to preset reference vector, generate projection coordinate-time curve, and extract image phase difference. Finally, according to the rotating direction of motor, image phase difference is converted into motor phase difference using unified formula, and accurate measurement under multiple working conditions is realized. The method solves the industry pain point that positive and negative phase difference measurement standards are not unified, and the measurement precision is high, which can be popularized to multiple working condition detection scenes of multi-machine drive rotating equipment.

Description

Technical Field

[0001] This invention relates to the field of synchronous detection technology for vibrating screens, and in particular to a method for measuring the phase difference of a multi-machine drive system. Background Technology

[0002] Vibrating screens are core equipment for material screening in industries such as petroleum, metallurgy, and chemicals. Especially in oil extraction, drilling fluid vibrating screens serve as primary solids control equipment in drilling mud purification systems. Their main function is to remove rock cuttings and other harmful solid particles from drilling fluid. This requires both a large processing capacity to recover as much of the costly drilling fluid as possible, and the removal of as many solid particles as possible to ensure downhole safety, increase drilling speed, and shorten drilling cycles. The vibrating motion of the drilling fluid vibrating screen is driven by the periodic rotation of an excitation motor, exhibiting periodic characteristics. The vibration and motor shaft system form a bidirectional coupling, maintaining dynamic balance through mechanical connections and inducing self-synchronization. This synchronization directly determines the system's screening capacity and solid particle conveying efficiency. The performance of a drilling fluid vibrating screen depends not only on the rheological properties of the drilling fluid and the physical characteristics of the particles in the mud, but also on the synchronization performance parameters of the vibrating screen. Currently, the industry primarily relies on high-speed cameras to capture images of the eccentric block of the excitation motor at different times on one side of the drive motor, and then calculates the synchronization phase difference of the drive motor through image analysis. However, existing measurement methods based on high-speed cameras have key technical limitations: the lack of a unified calculation standard for phase difference under forward and reverse rotation conditions leads to ambiguity in phase difference measurement results, making direct comparison and reuse of data under forward and reverse conditions impossible; furthermore, the phase difference measurement process is mostly done manually, which affects the accuracy and reliability of determining the synchronization status of the vibrating screen and makes it difficult to meet the precise detection needs under multiple operating conditions in actual engineering. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention aims to provide a method for measuring the phase difference between co-rotating and counter-rotating excitation motors, thereby solving problems such as the instability caused by the inaccurate measurement of the phase difference between excitation motors and the reduction of errors caused by manual phase difference measurement using traditional high-speed cameras.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a high-speed camera measurement method for detecting the synchronization phase difference of a multi-camera drive system (see flowchart for details). Figure 1 ), including the following steps: S1. Attach positioning pieces to the same position on each motor eccentric wheel. These positioning pieces are circular, highly reflective marking pieces (see...). Figure 2 ); S2. Place a high-speed camera parallel to the front of the eccentric block rotor of the excitation motor, so that the positioning plates on all motor rotors can be positioned at a frame rate. It was filmed in its entirety (see Figure 2 ); S3 drives the motor, and during the rotor rotation, the high-speed camera transmits the acquired image signals to the MATLAB software on the PC. S4. Identify the positioning patches in each frame of the image using software. , and the center of rotation , The coordinate position in the image coordinate system is denoted as a vector. , , , The coordinate system used is the default coordinate system in MATLAB's image processing, denoted as the image coordinate system. (See) Figure 3 ); S5. Obtain the relative position vectors of the two positioning plates with respect to their respective rotation centers through vector operations. , The coordinate components were denoised according to a time series, and the noise mainly came from the failure to accurately identify the positioning piece or the rotation center (see [link]). Figure 4 The time-series noise reduction mentioned above refers to obtaining vector data for each frame of the image. , After converting their coordinate components into coordinate-frame-number or coordinate-time curves, interpolation is performed on outliers in the curves to achieve image noise reduction (see [link]). Figure 5 ); S6, the first Frame images according to formula Converted to time And plot the projection coordinates-time curve. , The projected coordinates refer to the coordinates of a vector. , Projected onto the corresponding reference vector , Projection value on; , respectively with , The unit vector starting from, , and x The included angles of the axes are denoted as follows: , (See) Figure 6 ); , The reference vector needs to be fixed before measurement. The selection of the reference vector is arbitrary; for convenience, the coordinate base vector can be directly used as the reference vector. The specific formula for projection is: ; S7, Reading Curve , Image phase difference The image phase difference refers to the curve , Phase difference read from the same coordinate system (see Figure 7 and Figure 8 The specific method for obtaining image phase difference is as follows: Method 1: [The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full and Data projected onto reference vector , Two sine curves are obtained, and respectively... , according to By performing nonlinear function fitting, the fitted curve will be obtained. , initial phase , The resulting image phase difference is ; Method 2: Select curves separately , By performing a polynomial fitting on points near the peak and taking the derivative, the time corresponding to the peak can be found. Use this method to find the times of two adjacent wave peaks. and The phase difference of the image is indirectly obtained through the time difference. , The expected rotational speed is the speed value input to the motor before the test. Method two involves less computation than method one, and when high precision is not required, it can even directly read points near the peak value to estimate the peak time and quickly calculate the time difference. S8, through formula Image phase difference Converted to motor phase difference When the two motors rotate in the same direction k Take 1, when the two motors rotate in opposite directions. k Take 0. It is worth noting that for two exciter motors rotating in the same direction, and when... The phase difference of the motor in the same direction is the phase difference of the image. For two resonant motors rotating in opposite directions, if and only if The reverse phase difference of the motor is equal to the phase difference of the image. ,in It is the definition of the reverse phase difference. , These represent the initial phases of the reverse rotation; the positive and negative signs of the in-phase and reverse phase differences of the motor have the following meanings: express To compare First, it passes through the reference vector. express To compare Then it passes through the reference vector.

[0005] In summary, the present invention has the following beneficial effects: (1) High and stable measurement accuracy: high frame rate image capture and interpolation noise reduction result in small errors in the phase difference and angular velocity of the motors, and reliable data. (2) Low cost and easy to implement: conventional high-speed cameras are sufficient, no equipment modification is required, and non-contact operation reduces maintenance costs. (3) Strong adaptability: it covers forward and reverse rotation conditions and can be extended to multi-machine driven rotating equipment, with a wide range of applications. Attached Figure Description

[0006] Figure 1 This is a flowchart of a method for measuring the synchronous phase difference of a multi-camera drive system using a high-speed camera, according to the present invention.

[0007] Figure 2 This is a schematic diagram of a three-dimensional model of a test system for a high-speed camera detection multi-camera drive system synchronous phase difference measurement method according to the present invention.

[0008] Figure 3 This invention uses a MATLAB program to obtain points. The pixel coordinates, and by point The pixel coordinates of the point on the image Mark it. Coordinate system as follows: Figure 3 As shown in the upper left corner, this coordinate system is the default coordinate system used by MATLAB when processing images.

[0009] Figure 4 This is a schematic diagram illustrating noise generated due to identification errors.

[0010] Figure 5 For vectors A comparison chart showing the difference between before and after noise reduction. The two curves represent the x-axis and y-axis coordinates versus frame rate, respectively, with the ordinate being... The pixel coordinates of the component, with the horizontal axis representing the image frame number.

[0011] Figure 6 For vectors , Geometric representation of the projected coordinates.

[0012] Figure 7This is the projection coordinate-time curve obtained from a portion of the images (frames 1 to 200, a total of 5000 frames) during the same-direction rotation process processed by this invention, with reference vector... , All selected x Axis Parameters below the title in the image. , , , It is the angular velocity and initial phase obtained from nonlinear fitting.

[0013] Figure 8 The projection coordinate-time curve obtained by reversing the image of the portion processed by this invention (frames 1 to 200, a total of 5000 frames), with the reference vector being... .

[0014] Figure 9 An image used to measure the phase difference between two counter-rotating motors. By observing... When passing through the x-axis The angle between the x-axis and the x-axis.

[0015] Figure 10 An image used to measure the phase difference between two co-rotating motors. In engineering, the phase difference between motors rotating in the same direction is usually measured directly. and The angle between them. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the embodiments.

[0017] This invention discloses a method for measuring the synchronous phase difference of a multi-machine drive system using a high-speed camera. This method is applied to a dual-machine driven vibrating screen to measure the synchronous phase difference between two excitation motors. The system mainly consists of a vibrating screen prototype, a high-speed camera, MATLAB software, and positioning plates. The vibrating screen prototype primarily comprises a screen box, motor base, base, support springs, and two drive motors. The two motors rotate in the same or opposite directions, causing the screen box to vibrate along different trajectories.

[0018] Example 1: Two motors at the expected speed Reverse rotation ( Around Rotate clockwise. Around (Rotate counterclockwise); After the sieve box forms a stable straight trajectory, the high-speed camera rotates at a frame rate. Record continuously for 2.5 seconds, for a total of 5000 frames. Use frames 1-200 as the research focus. Follow steps S1-S8: S1. Attach a circular, highly reflective positioning piece to the central axis of the two motor eccentric wheels; S2. The camera's optical axis is parallel to the rotor's end face, ensuring the positioning plate... , and rotation center , Completely included in the field of view; S3. Start the motor. After it runs stably, start the high-speed camera and transfer the image to the PC. S4. Extract the XOY coordinates of each frame of the image using MATLAB. , , , Pixel coordinates, to obtain vector , , , And calculate the relative vector. , ; S5, to , of x , y The components are interpolated and denoised along the frame sequence to remove outliers. S6. Select reference unit vector , (and x The included angle of the axis is , ),Will , Projected onto the corresponding , Direction, to obtain the projected coordinates-time curve , ,in ; S7. Employing nonlinear fitting Extracting the initial phase , And calculate the image phase difference ; S8. Due to the motor rotating in the opposite direction, take... ,according to Convert the image phase difference into the motor phase difference.

[0019] For 7 different groups , Repeat the above process to obtain the motor reverse phase difference. (See table below for details), compared with manual readings (see...) Figure 9 ) deviation This confirms that the proposed method is unaffected by the selection of the reference vector under reverse operating conditions, and the angular velocity fitting error is only... ; .

[0020] Example 2: Two motors at the expected speed Rotation in the same direction ( Around Rotate clockwise. Around (Rotating clockwise); After the sieve box forms a stable elliptical trajectory, the high-speed camera moves at a frame rate Continuous shooting for 2.5 seconds, totaling 5000 frames, with frames 1-200 used as the research object. Steps S1-S7 are performed identically to those in Example 1, and in S8... For 7 different groups , Repeat the above process to obtain the same-direction phase difference of the motor. (See table below for details), compared with manual readings (see...) Figure 10 ) deviation This confirms that the proposed method is unaffected by the selection of the reference vector under unidirectional operating conditions, and the angular velocity fitting error is only... ; .

[0021] This embodiment verifies the effectiveness of the method based on a dual-motor driven vibrating screen. For other rotating equipment driven by multiple motors (such as vibrating feeders in the coal industry and multi-motor driven roller presses in the building materials field), the test procedure of this embodiment can be referred to. The shooting range of the high-speed camera can be adjusted according to the number of motors and rotor distribution of the equipment (such as using multiple cameras to shoot together). The positioning plate is pasted on the unobstructed and easily identifiable eccentric position of the rotor, so that the phase difference can be accurately measured.

Claims

1. A method for synchronous phase difference measurement in a multi-camera drive system based on a high-speed camera, characterized in that, Includes the following steps: S1. Attach a circular high-reflectivity positioning piece to the same position on each motor eccentric wheel; S2. Place the high-speed camera parallel to the front of the motor rotor so that all positioning plates can be imaged completely at a frame rate of no less than 2000fps. S3: Drive the motor to rotate, use a high-speed camera to capture images and transmit them to the image processing system; S4. Extract the pixel coordinates of each positioning patch and its corresponding rotation center in each frame of the image in the image coordinate system, and construct a relative position vector; S5. Perform interpolation and noise reduction on the coordinate components of the relative position vector according to the time series to remove outliers; S6. Project the noise-reduced relative position vector onto a pre-set reference vector to generate a projection coordinate-time curve; S7. Extract the image phase difference from the projection curve; S8. Based on the motor rotation direction, convert the image phase difference into the motor phase difference to achieve unified measurement under the same or opposite rotation conditions.

2. The method according to claim 1, characterized in that: The reference vector mentioned in step (6) is a fixed unit vector, which can be either a coordinate base vector or a manually set direction vector, used to unify the projection reference under different rotation directions.

3. The method according to claim 2, characterized in that: The methods for extracting the image phase difference in step (7) include: performing nonlinear fitting of the projection curve with a sine function to extract the initial phase and calculate the phase difference, or selecting points near the peak of the curve to perform polynomial fitting, obtaining the peak time difference by taking the derivative, and then calculating the phase difference.

4. The method according to any one of claims 1 to 3, characterized in that: In step (8), the motor phase difference is calculated using the following formula: ； in, For image phase difference, , For reference vector azimuth, This is the rotation direction coefficient; when rotating in the same direction... When rotating in the opposite direction .

5. The method according to any one of claims 1 to 4, characterized in that: The method is applicable to rotating systems driven by dual or multiple motors, including equipment such as vibrating screens, vibrating feeders, and roller presses.

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