Galvanometer correction device and method based on laser ultrasound

Abstract

The invention discloses a galvanometer correction device based on laser ultrasound, which comprises a correction plate and a control system, the correction plate comprises a circular substrate and at least three ultrasonic probes arranged on the circular substrate, a galvanometer is arranged above the circular substrate, and the control system comprises a galvanometer control card, a computer, an acquisition card and a signal amplifier. The signal amplifier is respectively connected with the at least three ultrasonic probes and is used for amplifying original ultrasonic signals and then transmitting the amplified ultrasonic signals to the acquisition card, and the acquisition card is used for digitalizing the amplified ultrasonic signals and then transmitting the digitalized ultrasonic signals to the computer; the galvanometer control card controls the pulse laser to enable the galvanometer to emit pulse laser at a specified position and excite ultrasonic waves on the circular substrate; the invention further discloses a galvanometer correction method based on laser ultrasound. According to the galvanometer correction method based on laser ultrasound, pattern marking and image measurement are not needed.

Description

Technical Field

[0001] The invention relates to the technical field of galvanometer correction, and in particular to a galvanometer correction device and method based on laser ultrasound. Background Art

[0002] Laser scanning technology is widely used in the industrial field, among which galvanometer scanning is the most widely used scanning method. The galvanometer motor has a small inertia, so the acceleration and deceleration are extremely fast, and the processing efficiency is extremely high. However, the galvanometer system will introduce various errors. First, the structure of the galvanometer motor layout determines that the motor angle and the position of the end spot present a nonlinear mapping relationship, and the linearity of the motor body also has a certain deviation. In addition, the design, manufacturing and installation errors of optical components also seriously affect the pointing accuracy of the laser beam. In summary, the galvanometer must be calibrated before it can be used normally.

[0003] The existing technology usually adopts the method of marking first and then measuring, that is, marking the standard pattern on the thin plate with a galvanometer, and then using an image measuring instrument to measure the deviation of the pattern and generate an error compensation table. This method has three disadvantages: 1. It relies on expensive image measuring instruments, and the measurement of image measuring instruments is very time-consuming; 2. If there is no image measuring instrument at some industrial sites, calibration is almost impossible. When there is a problem with the accuracy of the galvanometer at the industrial site, it is even necessary to transport the image measuring instrument weighing hundreds of kilograms or even tons to the site; 3. Each calibration consumes several sheets of thin plates for laser marking, resulting in material waste. Summary of the invention

[0004] In order to solve the shortcomings of existing calibration technology, especially the long calibration time, expensive calibration reliance and bulky image measuring instrument, and the need to consume a lot of marking consumables during the calibration process, the present invention proposes a galvanometer calibration device and method that does not require pattern marking or image measurement.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a galvanometer correction device based on laser ultrasound, comprising: a correction plate and a control system, wherein the correction plate comprises a circular substrate and at least three ultrasonic probes arranged on the circular substrate, a galvanometer is arranged above the circular substrate, the control system comprises a galvanometer control card, a computer, an acquisition card and a signal amplifier, the signal amplifier is respectively connected to at least three of the ultrasonic probes, and is used to amplify the original ultrasonic signal and transmit it to the acquisition card, the acquisition card is used to digitize the amplified ultrasonic signal and transmit it to the computer, and the galvanometer control card controls the pulse laser to make the galvanometer emit a pulse laser at a specified position and excite ultrasonic waves on the circular substrate.

[0006] As a further improvement of the present invention, it also includes a marking system, which includes a lifting platform and a mounting plate arranged on the lifting platform, and the pulse laser and the galvanometer are both arranged on the mounting plate.

[0007] As a further improvement of the present invention, the number of the ultrasonic probes is three, and the three ultrasonic probes are respectively bonded to a circular substrate using paraffin and are evenly distributed on a measuring circle.

[0008] As a further improvement of the present invention, the diameter of the circular substrate is greater than twice the diameter of the measuring circle.

[0009] As a further improvement of the present invention, the galvanometer control card also transmits the light output signal to the acquisition card for triggering the acquisition of the ultrasonic signal.

[0010] The present invention also provides a galvanometer correction method based on laser ultrasound, which is implemented by using the galvanometer correction device based on laser ultrasound as described above. The correction method comprises the following steps:

[0011] Step 1: Place the correction plate directly under the galvanometer, adjust the lifting platform so that the focus of the galvanometer is located on the correction plate, and adjust the position of the correction plate to ensure that the processing range of the galvanometer does not exceed the measurement circle formed by the three ultrasonic probes;

[0012] Step 2: The computer sends a correction position instruction to the galvanometer through the galvanometer control card. After the position is stable, the galvanometer control card sends a light emission instruction to the pulse laser and triggers the acquisition card to start collecting data.

[0013] Step 3: The pulsed laser excites ultrasonic waves at the landing point of the circular substrate, and the accurate coordinates of the laser landing point and the propagation speed of the ultrasonic waves in the substrate are calculated according to the coordinates of the three ultrasonic probes and the time of the received ultrasonic signals;

[0014] Step 4: The computer sends other correction position instructions to the galvanometer through the galvanometer control card, and repeats steps 2 and 3 to obtain the real laser landing point coordinates corresponding to other correction positions, and generates a correction table to complete the correction.

[0015] As a further improvement of the present invention, the step 3 is specifically as follows:

[0016] The exact coordinates of the laser landing point and the propagation speed of the ultrasonic wave in the substrate are solved by the following formula:

[0017] (T a v) 2 =(xx a ) 2 +(cy a ) 2

[0018] (T b v) 2 =(xx b )2 +(yy b ) 2

[0019] (T c v) 2 =(xx c ) 2 +(yy c ) 2

[0020] Among them, (x, y) is the coordinate of the point where the pulse laser lands on the circular substrate, (x a ,y a )、(x b ,y b ) and (x c ,y c ) is the coordinate system origin of the circular substrate center, the coordinates of the three ultrasonic probes, T a , T b and T c is the time of receiving the ultrasonic signal, and v is the propagation speed of the ultrasonic wave in the circular substrate.

[0021] The beneficial effects of the present invention are:

[0022] The present invention proposes a galvanometer correction device and method based on laser ultrasound. The method does not require marking during the correction process, so it does not consume marking consumables and does not rely on image measuring instruments. In addition, the device is small in size and light in weight, and is suitable for carrying and using at any time in industrial sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of a galvanometer correction device based on laser ultrasound in an embodiment of the present invention;

[0024] Figure 2 is a timing diagram of a signal waveform in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the circular substrate size and probe position in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] Example

[0028] like Figure 1 As shown, a galvanometer correction device based on laser ultrasound includes a correction plate, a control system and a marking system:

[0029] The correction plate includes an ultrasonic probe A 8, an ultrasonic probe B 9, an ultrasonic probe C10 and a circular substrate 11. The ultrasonic probe A 8, the ultrasonic probe B 9, and the ultrasonic probe C10 are respectively bonded to the circular substrate 11 with paraffin and are evenly distributed on a measuring circle. The size of the measuring circle can cover the galvanometer marking range. The diameter of the circular substrate 11 is slightly larger than twice the diameter of the measuring circle.

[0030] The control system includes a galvanometer control card 1, a computer 2, an acquisition card 3, and a signal amplifier 4 which are arranged in sequence. The signal amplifier 4 is connected to an ultrasonic probe A 8, an ultrasonic probe B 9, and an ultrasonic probe C10, and amplifies the original weak ultrasonic signal and transmits it to the acquisition card 3. The acquisition card 3 digitizes the amplified ultrasonic signal and transmits it to the computer 2. The galvanometer control card 1 can control the pulse laser 6 and the galvanometer 12 to emit a pulse laser at a specified position and excite ultrasonic waves on a circular substrate 11. The galvanometer control card 1 also transmits the light output signal to the acquisition card 3 for triggering the acquisition of ultrasonic signals.

[0031] The marking system comprises a lifting platform 5, a pulse laser 6, a mounting plate 7 and a galvanometer 12 which are arranged in sequence.

[0032] This embodiment also provides a galvanometer correction method based on laser ultrasound, which adopts the following method:

[0033] Step 1: Place the correction plate directly below the galvanometer 12, adjust the lifting platform 5 so that the focus of the galvanometer 12 is located on the correction plate, and adjust the position of the correction plate to ensure that the processing range of the galvanometer 12 does not exceed the measurement circle formed by the three ultrasonic probes;

[0034] Step 2, the computer 2 sends a correction position instruction to the galvanometer 12 through the galvanometer control card 1. After the position is stable, the galvanometer control card 1 sends a light emission instruction to the pulse laser 6, and at the same time triggers the acquisition card 3 to start collecting data;

[0035] Step 4: The pulse laser excites ultrasonic waves at the landing point P (x, y) of the circular substrate 11. Since the three ultrasonic probes (with the center of the substrate as the origin of the coordinate system, the positions of the three probes are (x a ,y a )、(x b ,y b ) and (x c ,y c )) are at different distances from the laser landing point P(x, y), so the time of receiving the ultrasonic signal is different, and they are T a , T b and T c , assuming that the propagation speed of ultrasound in the substrate is v, the data of the three ultrasonic probes are analyzed on computer 2 to solve the following equations:

[0036]

[0037] The accurate coordinates of the laser landing point position P (x, y) and the sound speed v can be obtained;

[0038] Each time the laser landing point is calculated, three ultrasonic probes are used to obtain three sets of equations to solve the laser landing point position P (x, y) and the sound speed v, avoiding the change of sound speed caused by factors such as temperature and material stress release, and ensuring the calculation accuracy.

[0039] Step 4, the computer 2 sends other correction position instructions to the galvanometer 12 through the galvanometer control card 1, and repeats steps 2 and 33 to obtain the real laser landing point coordinates corresponding to other correction positions, and generates a correction table to complete the correction.

[0040] like Figure 2 As shown in the figure, when the pulse laser emits light, the acquisition card is synchronously triggered to collect the signals of the three ultrasonic probes. The laser propagates at the speed of light in the air and the distance from the laser to the substrate is very short, so the time for light propagation can be ignored. However, compared with the speed of light, the time T for the ultrasonic wave emitted from the laser landing point to propagate to the three probes is a , T b and T c There is a clear difference. The substrate is made of aluminum or iron, and its sound speed is about 4000-6000m / s. Calculated at a sound speed of 5000m / s, it is converted to a microscopic scale of 5μm / ns. The acquisition card under the existing technical level can achieve a sampling rate of 5GHz (sampling period of 0.2ns), and the calculable resolution is 1 micron. Therefore, the time difference between the three probes receiving the ultrasonic wave and the laser emitting light can fully achieve micron-level laser landing point position measurement accuracy.

[0041] like Figure 3 As shown, the black dots correspond to three ultrasonic probes, the circle where the three ultrasonic probes are located is the measuring circle, and the inscribed square is the galvanometer marking area. When the laser falls within the galvanometer marking area, the solution of the equation group is unique. Since an echo will be generated when the ultrasonic wave propagates to the boundary of the circular substrate 11, in order to avoid the influence of the echo on the ultrasonic probe, it is necessary to ensure that the echo arrives later than the ultrasonic wave. According to the size in the figure, it can be calculated that as long as e is greater than f / 2, the above purpose can be achieved.

[0042] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A galvanometer correction device based on laser ultrasound, characterized in that: include: A correction plate and a control system, wherein the correction plate comprises a circular substrate and at least three ultrasonic probes arranged on the circular substrate, a galvanometer is arranged above the circular substrate, and the control system comprises a galvanometer control card, a computer, an acquisition card and a signal amplifier, wherein the signal amplifier is respectively connected to the at least three ultrasonic probes and is used to amplify the original ultrasonic signal and transmit it to the acquisition card, and the acquisition card is used to digitize the amplified ultrasonic signal and transmit it to the computer, and the galvanometer control card controls the pulse laser to make the galvanometer emit a pulse laser at a specified position and excite ultrasonic waves on the circular substrate.

2. The laser ultrasound-based galvanometer correction device according to claim 1, characterized in that: It also includes a marking system, which includes a lifting platform and a mounting plate arranged on the lifting platform, and the pulse laser and the galvanometer are both arranged on the mounting plate.

3. The laser ultrasound-based galvanometer correction device according to claim 2, characterized in that: There are three ultrasonic probes, and the three ultrasonic probes are respectively bonded to a circular substrate using paraffin and are evenly distributed on a measuring circle.

4. The laser ultrasound-based galvanometer correction device according to claim 3, characterized in that: The diameter of the circular substrate is greater than twice the diameter of the measuring circle.

5. The laser ultrasound-based galvanometer correction device according to claim 4, characterized in that: The galvanometer control card also transmits the light output signal to the acquisition card for triggering the acquisition of ultrasonic signals.

6. A galvanometer correction method based on laser ultrasound, characterized in that: The correction method is implemented by using the laser ultrasound-based galvanometer correction device as claimed in claim 5, and the correction method comprises the following steps: Step 1: Place the correction plate directly under the galvanometer, adjust the lifting platform so that the focus of the galvanometer is located on the correction plate, and adjust the position of the correction plate to ensure that the processing range of the galvanometer does not exceed the measurement circle formed by the three ultrasonic probes; Step 2: The computer sends a correction position instruction to the galvanometer through the galvanometer control card. After the position is stable, the galvanometer control card sends a light-emitting instruction to the pulse laser and triggers the acquisition card to start collecting data. Step 3: The pulsed laser excites ultrasonic waves at the landing point of the circular substrate, and the accurate coordinates of the laser landing point and the propagation speed of the ultrasonic waves in the substrate are calculated according to the coordinates of the three ultrasonic probes and the time of the received ultrasonic signals; Step 4: The computer sends other correction position instructions to the galvanometer through the galvanometer control card, and repeats steps 2 and 3 to obtain the real laser landing point coordinates corresponding to other correction positions, and generates a correction table to complete the correction.

7. The laser ultrasound-based galvanometer correction method according to claim 6, characterized in that: The step 3 is as follows: The exact coordinates of the laser landing point and the propagation speed of the ultrasonic wave in the substrate are solved by the following formula: (T a ·v) 2 =(x-x a ) 2 +(y-y a ) 2 (T b ·v) 2 =(x-x b ) 2 +(y-y b ) 2 (T c ·v) 2 =(x-x c ) 2 +(y-y c ) 2 Among them, (x, y) is the coordinate of the point where the pulse laser lands on the circular substrate, (x a ,y a )、(x b ,y b ) and (x c ,y c ) is the coordinate system origin of the circular substrate center, the coordinates of the three ultrasonic probes, T a 、T b and T c is the time of receiving the ultrasonic signal, and v is the propagation speed of the ultrasonic wave in the circular substrate.

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