Galvanometer performance parameter acquisition method

Abstract

The invention discloses a galvanometer performance parameter acquisition method. A main control board sends a starting signal, an image acquisition signal and a rotation signal to a line laser, a camera and a driving mechanism in a galvanometer; the camera collects a laser strip image; the laser strip image and the sending time of the image acquisition signal are stored in an associated mode; the galvanometer is reset, the main control board delays the image acquisition signal for multiple times, and multiple images are repeatedly acquired; sorting the plurality of images according to image acquisition signal emission moments and extracting characteristic lines of laser strips; calculating a pixel distance Si between the feature lines in two adjacent images; obtaining a response time parameter, a rotation parameter and a deflection precision parameter of the galvanometer according to Si; according to the method, images are acquired for multiple times in a camera delay image acquisition mode, and after all the images are sequenced according to time, laser stripes in all the images can reflect moving tracks of the laser stripes; the method has the characteristics of being high in automation degree and accurate in calculation.

Description

Technical Field

[0001] This invention relates to the field of performance testing, and more specifically to a method for obtaining galvanometer performance parameters. Background Technology

[0002] A laser galvanometer vision inspection sensor mainly consists of a galvanometer, a laser, and a camera. Typically, the drive mechanism within the galvanometer is required to rotate continuously at a uniform speed. The thickness of the stripes and the spacing between black and white stripes are adjusted by controlling the on / off time of the laser. The camera acquires stripe coding information and processes the surface information of the object under test. To obtain accurate stripe surface information, precise timing coordination between the galvanometer and the laser is required to ensure accurate projection of the stripe coding information. Therefore, the following performance parameters need to be obtained before the galvanometer is put into use:

[0003] 1. Response Time: There is a certain delay in the control and execution of the galvanometer, namely, the time difference (response time) between the galvanometer receiving the rotation signal from the main control board and the drive mechanism actually starting to drive the lens to rotate continuously; therefore, the response time needs to be obtained before the galvanometer is put into use so that time compensation can be performed later.

[0004] II. Rotation Parameters: From the start to the end of rotation, the drive mechanism undergoes three processes: acceleration, uniform rotation, and deceleration. The acceleration and deceleration processes of the galvanometer can easily lead to uneven light stripes, increasing uncontrollable factors. Therefore, it is necessary to obtain the time period of the uniform rotation process of the galvanometer.

[0005] III. Deflection accuracy parameters: In precision measurement scenarios, the accuracy requirements for the projection of fringe positions are extremely high. Therefore, it is necessary to verify whether the deflection accuracy of the galvanometer meets the usage requirements. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for obtaining galvanometer performance parameters. By using a time-lapse camera to acquire multiple images, the laser stripes in each image reflect the deflection trajectory of the galvanometer; thereby obtaining the galvanometer's performance parameters. This method requires no manual intervention, significantly reducing the quality control workload for production personnel and ensuring that the galvanometer's performance parameters meet requirements.

[0007] The technical solution is as follows:

[0008] A method for obtaining the performance parameters of a galvanometer, wherein the galvanometer includes a driving mechanism and a lens that rotates with the driving mechanism, and the driving mechanism is controlled by a main control board;

[0009] A line laser and a camera are positioned around the lens, both controlled by a main control board; a planar plate is positioned in front of the galvanometer; the performance parameters of the galvanometer are obtained using the following steps:

[0010] 1) The main control board controls the timer to keep a continuous count and sends start signal, image acquisition signal and rotation signal to the line laser, camera and drive mechanism respectively;

[0011] The line laser continuously projects laser light onto the lens according to the activation signal sent by the main control board;

[0012] The drive mechanism drives the lens to rotate continuously from a preset starting angle to a preset ending angle according to the rotation signal sent by the main control board, so as to continuously reflect the laser onto the flat plate.

[0013] The camera acquires the laser strip image projected onto the flat panel based on the image acquisition signal emitted by the main control board;

[0014] The main control board associates and stores the laser bar image with the time of the acquisition signal emission;

[0015] Among them, the moment when the main control board sends the start signal and the moment when it first sends the image acquisition signal are no later than the moment when the rotation signal is sent;

[0016] 2) The timer is reset, the mirror in the galvanometer is reset, and the main control board delays the transmission time of the current image acquisition signal. Continue with step 1). This is the preset delay step size;

[0017] 3) Repeat step 2) multiple times to store multiple images;

[0018] Multiple images are sorted according to the order in which the image acquisition signals were transmitted;

[0019] Feature lines of the laser stripe are extracted from multiple images, where the feature lines are center lines or single-sided edge lines, and the positions of the feature lines in the images are recorded.

[0020] 4) Calculate the pixel distance S between feature lines in two adjacent images sequentially. i i = 1, 2 ... N-1, where N represents the total number of images; according to S i The response time parameter of the galvanometer is obtained by measuring the time difference from zero to non-zero.

[0021] Based on adjacent S i The difference between the values ​​is used to obtain the rotation parameters of the galvanometer, which include the acceleration rotation time, the uniform rotation time, and the deceleration rotation time.

[0022] During the time interval of uniform rotation of the galvanometer, according to S i Calculate the angle between two adjacent laser stripes i Based on the included angle i and The theoretical angle value of the galvanometer deflection within a time period The difference between the values ​​is used to obtain the deflection accuracy parameters of the galvanometer.

[0023] Preferably, step 1) also includes an indicator light, which is installed within the field of view of the camera and controlled by the main control board. The indicator light is turned on when the main control board sends a rotation signal.

[0024] Before or during step 2), the main control board control indicator light is turned off;

[0025] In step 4), after obtaining the response time parameter of the galvanometer, an additional compensation time t is applied to the response time parameter, where time t is the difference between time T and the time when the rotation signal is emitted, and time T is the image acquisition time corresponding to the first acquisition of the image of the indicator light illuminating.

[0026] further, Where H is the vertical distance from the lens to the flat plate.

[0027] Preferably, the width of the laser stripe in the laser stripe image is between 1 and 5 pixels.

[0028] Furthermore, in step 1), the main control board sends M image acquisition signals to the camera; M ≥ 1, and when M > 1, the time interval between the M image acquisition signals is the same and greater than 1. ;

[0029] In step 2), the main control board delays the transmission time of the M image acquisition signals. ;

[0030] In step 3), the number of times step 2) is repeated is ≥ Where G1 represents the time interval between the moment the first image acquisition signal is issued and the moment the rotation signal is issued; G2 represents the time required for the lens to rotate continuously from the preset starting angle to the preset ending angle.

[0031] This method solves the problem of obtaining galvanometer performance parameters. By using a time-lapse camera to acquire images multiple times, each image contains only one laser stripe. After sorting the images by time, the laser stripe in each image can reflect the deflection trajectory of the galvanometer. Thus, the acceleration, constant speed, deceleration, response time, and deflection accuracy of the galvanometer at various times can be obtained.

[0032] This method requires no manual intervention, greatly reducing the quality inspection workload of production personnel and ensuring that the performance parameters of the galvanometer meet the requirements. Attached Figure Description

[0033] Figure 1 This is a schematic diagram showing the positional relationship between the galvanometer, line laser, camera, and planar plate.

[0034] Figure 2 This is a diagram showing the comparison of the emission times of each signal when step 1) is executed multiple times;

[0035] Figure 3 This is a schematic diagram illustrating the changes in the position of feature lines after multiple images are sorted sequentially according to their acquisition time. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0037] A method for obtaining galvanometer performance parameters, such as Figure 1 As shown, there is a drive mechanism and a lens that rotates with the drive mechanism, the drive mechanism being controlled by the main control board;

[0038] A line laser and a camera are positioned around the lens, both controlled by a main control board; a planar plate is positioned in front of the galvanometer; the performance parameters of the galvanometer are obtained using the following steps:

[0039] 1) The main control board controls the timer to keep a continuous count and sends start signal, image acquisition signal and rotation signal to the line laser, camera and drive mechanism respectively;

[0040] The line laser continuously projects laser light onto the lens according to the activation signal sent by the main control board;

[0041] The drive mechanism drives the lens to rotate continuously from a preset starting angle to a preset ending angle according to the rotation signal sent by the main control board, so as to continuously reflect the laser onto the flat plate.

[0042] The camera acquires the laser strip image projected onto the flat panel based on the image acquisition signal emitted by the main control board;

[0043] The main control board associates and stores the laser bar image with the time of the acquisition signal emission;

[0044] Among them, such as Figure 2 The moment when the main control board sends the start signal and the moment when it first sends the image acquisition signal shall not be later than the moment when the rotation signal is sent.

[0045] Explanatory: When step 1) is executed for the first time, the three signals are issued simultaneously, or the start signal and the image acquisition signal are issued first, followed by the drive signal;

[0046] 2) The timer is reset, and the mirror in the galvanometer is reset, such as... Figure 2 The main control board delays the transmission time of the current image acquisition signal. Continue with step 1). This is the preset delay step size;

[0047] 3) Repeat step 2) multiple times to store multiple images (e.g. Figure 3 );

[0048] Multiple images are sorted according to the order in which the image acquisition signals were transmitted;

[0049] Feature lines of the laser stripe are extracted from multiple images, where the feature lines are center lines or single-sided edge lines, and the positions of the feature lines in the images are recorded.

[0050] 4) Calculate the pixel distance S between feature lines in two adjacent images sequentially. i i = 1, 2 ... N-1, where N represents the total number of images; according to S i The response time parameter of the galvanometer is obtained by measuring the time difference from zero to non-zero.

[0051] Based on adjacent S i The difference between the values ​​is used to obtain the rotation parameters of the galvanometer, which include the acceleration rotation time, the uniform rotation time, and the deceleration rotation time.

[0052] During the time interval of uniform rotation of the galvanometer, according to S i Calculate the angle between two adjacent laser stripes i Based on the included angle i and The theoretical angle value of the galvanometer deflection within a time period The difference between the values ​​is used to obtain the deflection accuracy parameters of the galvanometer.

[0053] in, This can be achieved through multiple adjustments and experiments; the typical response time is between 0.05 and 0.5 ms. Less than the response time of the galvanometer, typically, Range 0.05~0.5ms.

[0054] Specifically, in this embodiment, the process of obtaining the response time parameter is as follows:

[0055] Record the first S greater than zero i The corresponding image number K, the time when the image acquisition signal of the Kth image is emitted is denoted as time T1, and the difference between the time when the rotation signal is emitted and the image acquisition time T1 is denoted as the response time parameter of the galvanometer.

[0056] The process for obtaining the rotation parameters of the galvanometer (acceleration time, constant velocity time, deceleration time) is as follows:

[0057] Calculate v i =S i / ; and let v i+1 -v iMultiple differences are obtained. The time period when the difference is greater than zero is recorded as the acceleration time, the time period when the speed value is not zero but the difference is equal to zero is recorded as the uniform speed time, and the time period when the difference is less than zero is recorded as the deceleration time.

[0058] Where H is the vertical distance from the lens to the flat plate.

[0059] For ease of understanding, Taking step 1) as an example, which is executed 8 times, the exemplary data is shown in the table below:

[0060]

[0061] From the table above, we can conclude that the first S greater than zero... i The corresponding image number K=3, and the time when the image acquisition signal of the third image is emitted is denoted as time T1=0.2ms. The difference between the time when the rotation signal is emitted (0.1ms) and the image acquisition time T1 is denoted as the response time parameter of the galvanometer.

[0062] The acceleration rotation time range of the galvanometer is 0.1ms~0.3ms, the uniform rotation time range is 0.3~0.4ms, and the deceleration rotation time range is 0.4~0.6ms.

[0063] As a preferred implementation method, such as Figure 1 In step 1) of this embodiment, an indicator light is also included. It is installed within the field of view of the camera and is controlled by the main control board. When the main control board sends a rotation signal, it controls the indicator light to turn on.

[0064] Before or during step 2), the main control board control indicator light is turned off;

[0065] In step 4), after obtaining the response time parameter of the galvanometer, an additional compensation time t is applied to the response time parameter (the response time is increased by t), where time t is the difference between time T and the time when the rotation signal is emitted, and time T is the image acquisition time corresponding to the first acquisition of the image where the indicator light is on. Figure 3 Time T is the acquisition time corresponding to the second image.

[0066] In this solution, the camera uses short exposure (exposure time set in the microsecond range) to ensure that the width of the laser stripes (thin light stripes) in the captured image is between 1 and 5 pixels. In practice, the camera exposure time can be adjusted and tested multiple times to find a suitable value.

[0067] More specifically, in step 1), the main control board sends M image acquisition signals to the camera; M≥1, that is, executing step 1 once can acquire only one image or multiple images (M>1).

[0068] When M > 1, the time interval between the M image acquisition signals is the same and greater than 1. ;

[0069] In step 2), the main control board delays the transmission time of the M image acquisition signals. ;

[0070] In step 3), the number of times step 2) is repeated is ≥ Where G1 represents the time interval between the moment the first image acquisition signal is issued and the moment the rotation signal is issued; G2 represents the time required for the lens to rotate continuously from the preset starting angle to the preset ending angle.

[0071] This method acquires images multiple times through time-lapse photography using a camera. After sorting the images by time, the laser stripes in each image can reflect the movement trajectory of the laser stripes. This allows us to obtain the acceleration, constant speed, deceleration status, response time, and deflection accuracy of the galvanometer at various moments.

[0072] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the precise forms disclosed; obviously, many changes and variations are possible in accordance with the foregoing teachings. The exemplary embodiments were chosen and described to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to implement and utilize various exemplary embodiments of the invention, as well as their different alternatives and modifications. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A method for obtaining galvanometer performance parameters, wherein the galvanometer includes a driving mechanism and a lens that rotates with the driving mechanism, and the driving mechanism is controlled by a main control board; Its features are, A line laser and a camera are placed around the lens, both controlled by the main control board; a planar plate is placed in front of the galvanometer. The following steps are used to obtain the performance parameters of the galvanometer: 1) The main control board controls the timer to keep a continuous count and sends start signal, image acquisition signal and rotation signal to the line laser, camera and drive mechanism respectively; The line laser continuously projects laser light onto the lens according to the activation signal sent by the main control board; The drive mechanism drives the lens to rotate continuously from a preset starting angle to a preset ending angle according to the rotation signal sent by the main control board, so as to continuously reflect the laser onto the flat plate. The camera acquires the laser strip image projected onto the flat panel based on the image acquisition signal emitted by the main control board; The main control board associates and stores the laser bar image with the time of the acquisition signal emission; Among them, the moment when the main control board sends the start signal and the moment when it first sends the image acquisition signal are no later than the moment when the rotation signal is sent; 2) The timer is reset, the mirror in the galvanometer is reset, and the main control board delays the transmission time of the current image acquisition signal. Continue with step 1). This is the preset delay step size; 3) Repeat step 2) multiple times to store multiple images; Multiple images are sorted according to the order in which the image acquisition signals were transmitted; Feature lines of the laser stripe are extracted from multiple images, where the feature lines are center lines or single-sided edge lines, and the positions of the feature lines in the images are recorded. 4) Calculate the pixel distance S between feature lines in two adjacent images sequentially. i i = 1, 2 ... N-1, where N represents the total number of images; according to S i The response time parameter of the galvanometer is obtained by measuring the time difference from zero to non-zero. Based on adjacent S i The difference between the values ​​is used to obtain the rotation parameters of the galvanometer, which include the acceleration rotation time, the uniform rotation time, and the deceleration rotation time. During the time interval of uniform rotation of the galvanometer, according to S i Calculate the angle between two adjacent laser stripes i Based on the included angle i and The theoretical angle value of the galvanometer deflection within a time period The difference between the values ​​is used to obtain the deflection accuracy parameters of the galvanometer.

2. The method for adjusting the assembly parameters of the galvanometer sensor as described in claim 1, characterized in that: In step 1), an indicator light is also included, which is installed within the field of view of the camera and controlled by the main control board. When the main control board sends a rotation signal, it controls the indicator light to turn on. Before or during step 2), the main control board control indicator light is turned off; In step 4), after obtaining the response time parameter of the galvanometer, an additional compensation time t is applied to the response time parameter, where time t is the difference between time T and the time when the rotation signal is emitted, and time T is the image acquisition time corresponding to the first acquisition of the image of the indicator light illuminating.

3. The method for obtaining galvanometer performance parameters as described in claim 1, characterized in that: Where H is the vertical distance from the lens to the flat plate.

4. The method for obtaining galvanometer performance parameters as described in claim 1, characterized in that: The width of the laser stripe in the laser stripe image is between 1 and 5 pixels.

5. The method for obtaining galvanometer performance parameters as described in claim 1, characterized in that: In step 1), the main control board sends M image acquisition signals to the camera; M ≥ 1. When M > 1, the time interval between the M image acquisition signals is the same and greater than 1. ; In step 2), the main control board delays the transmission time of the M image acquisition signals. ; In step 3), the number of times step 2) is repeated is ≥ Where G1 represents the time interval between the moment the first image acquisition signal is issued and the moment the rotation signal is issued; G2 represents the time required for the lens to rotate continuously from the preset starting angle to the preset ending angle.

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