CN112842520B - Device and method for planning self-adaptive path of welding seam of in-vitro laser biological tissue welding - Google Patents

Abstract

The invention relates to a self-adaptive path planning device and a self-adaptive path planning method for a laser biological tissue welding seam. The device comprises a laser emitting device, an optical filter and an optical sensing device. The laser emitting device can emit multiple parallel beams simultaneously and comprises a laser generator and a laser beam splitter, wherein the laser beam splitter divides one laser beam into multiple beams. The optical filter device is of a multi-channel structure, and each channel is provided with an optical filter. The optical sensing device is internally provided with a CCD camera and has a real-time visual function; and the laser scans the welding seam in a segmented way, and then images of all positions of the welding seam are overlapped, so that the identifiability of the welding seam under the natural light condition is enhanced. By utilizing the device to weld biological tissues, path planning can be carried out on various track incision weld joints so as to realize self-adaptive welding, the device is suitable for welding and sewing skin tissues and muscle tissues, and the weld joint has strong adaptability, high recognition capability and quick response, and can accurately recognize the fine weld joint which is tightly attached.

Description

An in vitro laser biological tissue welding seam adaptive path planning device and its method

Technical field

The invention relates to an in vitro laser biological tissue welding seam adaptive path planning device and a method thereof, and belongs to the field of in vitro laser biological tissue welding, especially the field of laser surgery and laser-assisted suturing.

Background technique

Generally, humans or animals are accidentally injured or wounds are produced on the body during surgical operations. Small wounds recover quickly through the body's self-healing ability, while larger wounds require treatment to heal. Otherwise, it will take time to close and repair the wound. Excessive length increases the possibility of bacterial infection in the environment. Therefore, a treatment method that can effectively close the wound immediately and make the wound water-tight is of great significance to reduce the risk of infection and accelerate wound healing. So far, larger wounds are still closed and sealed with needles and threads. However, needles and threads only mechanically pull and squeeze the tissues together, causing kinks in the healing tissue, and unclosed cracks between the suture pins are prone to occur, causing infection. ; In addition, the suturing process is a process that introduces new trauma and increases the formation of scar tissue. In view of the serious shortcomings of needle and thread suturing, laser-assisted suturing of biological tissue is a technology that has been proposed in the surgical field to overcome some problems that may occur in the traditional needle and thread suturing process. It has been widely proven that in laser welded wounds, there is no rejection reaction, a better and faster healing process, and the process of reorganization of tissue structure results in a scarless, instant watertight closure of the wound, thereby reducing the risk of infection. There are two different methods of laser tissue suturing: 1. Laser tissue welding (LTW), in which laser energy is applied to the edges of the tissue; 2. Laser tissue brazing (LTS), in which laser tissue is added to the near edges of the tissue before laser processing. Substances (such as solder). Despite significant experimental results in recent years, the application of laser welding technology is limited by the degree of automation and the complexity of matching different parameters to different tissues, as well as the lack of high reproducibility of results.

Looking for relevant reports on existing biological tissue laser welding technology, laser biological tissue welding equipment can generally only complete the suturing of straight line welds, but does not perform adaptive welding of irregular curved welds. The application scenario of a single straight weld seam means that its application scope is limited, that is, the product has low flexibility, low intelligence and low adaptability.

Contents of the invention

The purpose of the present invention is to provide an in vitro laser biological tissue welding seam adaptive path planning device and a method thereof, which have the functions of beam adjustment-spacing adjustment weld tracking-parameter adaptation-intelligent discrimination of welding quality, and are suitable for medical lasers For suture welding of soft tissues such as surgical skin tissue, it can realize real-time seam tracking function and process parameter adaptation during in vitro laser biological tissue welding, and self-judge the welding quality compliance characteristics. It is suitable for suture welding of soft tissues such as medical laser surgical skin tissue.

The technical solution to achieve the purpose of the present invention is:

An in vitro laser biological tissue welding seam tracking device, including:

A multi-beam laser parallel scanning emission device; a laser generator, a laser beam splitter and a laser galvanometer; the laser beam splitter divides a laser into multiple beams;

The laser beam splitting device is equipped with a photonic crystal fiber beam splitter and a focusing mirror, and the beams of each channel are emitted in parallel; the beam splitting mirror can be adjusted according to the number of laser beams, and the distance between the beams can be adjusted;

The laser beam splitter contains a beam number adjusting device to adjust the number n of beams.

The n is 1 to 3.

Optical filters include brackets and filters; among them, the filters are used to filter interference light, improve imaging quality and accuracy, and thereby improve recognition capabilities.

Optical sensing device; including a visual sensing system consisting of a CCD camera.

The above-mentioned in vitro laser biological tissue welding seam tracking device and laser beam splitter can change the distance between the beams obtained after splitting by adjusting the laser beam splitter; the laser beam splitter is equipped with a light shielding plate. Unnecessary beams can be blocked and the number of beams can be adjusted.

As described above, in an in vitro laser biological tissue welding seam tracking device, the filter in the optical filter is a broadband filter, and the transmittance of ultraviolet rays in the wavelength band of 200-380nm and infrared rays greater than 700nm is less than 3 *10 ^-4 .

As described above, in an in vitro laser biological tissue welding seam tracking device, the optical sensing device is connected to a computer, and through software image processing, the welding laser position is automatically corrected in real time, and the welding point position change information is programmed and transmitted to the robotic arm.

As described above, in an in vitro laser biological tissue welding seam tracking device, during the laser scanning process, the moving interval is 2mm to leave enough space to identify the distortion of the laser imaging and avoid mutual interference due to the small interval; if the distance is too large, If it is large, the imaging will not be precise enough and the weld recognition accuracy will be reduced.

As described above, in an in vitro laser biological tissue welding seam tracking device, the optical sensing device is connected to a computer. According to the acquired original image information, it is superimposed with the laser-scanned welding seam image. By finding the third laser line segment in the image, A distortion point is used as a feature point to identify the starting point of the weld. When the imaging laser moves along the weld, the image is transmitted in real time as the weld changes. The gray value of the image is extracted. The shadow formed by the weld under natural light conditions is used as the Feature value, extract the welding seam contour, identify the welding seam position, and program and transmit the welding point position adjustment information to the robot arm. At the same time, the welding structure is modeled in three-dimensional space, the coordinate points of the weld are positioned, and the welding scan path is planned according to the size and shape of the weld area. The scan path includes linear, zigzag, and segmented types.

An in vitro laser biological tissue welding seam tracking method includes the following steps:

Step 1: Set the corresponding emissivity according to the physical and optical characteristics of the target biological tissue, and determine the required number of laser beams n according to the length of the weld;

Step 2: Select the appropriate laser beam spacing s according to the shape and length of the welded cut, 1mm≤s≤3mm, and 3≤n×s≤5;

Step 3: Start the optical sensing device, open the weld tracking software, and obtain the optical image; leave enough space to identify the distortion of the laser imaging and avoid mutual interference and superposition because the distance is less than 600 μm; if the distance is greater than 2 mm, the imaging is not precise enough. The accuracy of weld seam identification is reduced;

Step 4: Based on the optical characteristics of the biological tissue obtained by the optical sensor, the software automatically matches the corresponding welding process parameters in the database, and turns on the welding light source for welding;

Step 5: Based on the real-time image obtained by the optical sensing device, the software uses an image recognition algorithm to find the characteristic points of the weld, thereby identifying the starting point of the weld, and adjusts the position information of the corresponding solder point according to the change in the shape of the weld during the welding process. It is transmitted to the robotic arm to achieve real-time feedback adjustment. When the characteristics of the welding end point are extracted from the image, the laser is turned off and the welding is completed.

The adaptive welding parameters as mentioned above are determined according to the optical properties of the target biological tissue, such as reflection coefficient and transmission coefficient.

Preferably, the number n of laser beams is selected to be 1 to 3.

Compared with the prior art, the significant advantages of the present invention are:

1. The device provided by the present invention performs laser welding of biological tissue without strict requirements on the straightness of the incision of biological tissue. It can adapt to welding seams of various shapes such as curves and non-planar incisions, and has high adaptability to wounds;

2. The laser generating device provided by the invention has an adjustable number of laser beams and an adjustable laser beam interval, which helps to improve the efficiency of optical sensors in identifying weld seams and reduce welding preparation time;

3. The optical sensing device described in the device provided by the present invention is a visual sensing recognition system, and can identify the optical characteristics of biological tissue on the images obtained by the recognition system, and automatically match the welding process parameters;

4. The device provided by the present invention can realize real-time adjustment of the position of the solder joint based on real-time optical sensing. The device can be used to weld biological tissue, and the welding quality can be controlled. During the implementation process, the position of the solder joint can be automatically adjusted in real time based on deformation feedback. , broadening the application prospects of automated laser biological tissue welding in vitro.

Description of the drawings

Figure 1 shows the intensity histogram obtained by ordinary linear laser scanning welding and path planning adaptive welding.

Figure 2 shows the comparison of the morphology effects of ordinary linear laser scanning welding and path planning adaptive welding (1a) Front surface morphology of linear scanning welding; (1b) Back surface morphology of linear scanning welding; (1c) Side surface morphology of linear scanning welding (2a) Adaptive welding front morphology; (2b) Adaptive welding back morphology; (2c) Adaptive welding side morphology.

Figure 3 is a schematic diagram of the weld seam tracking laser arrangement.

Figure 4 is a schematic diagram of the weld tracking device system for in vitro laser biological tissue welding according to the present invention.

Figure 5 is a schematic diagram of the optical signal transmission path of the present invention.

Figure 6 shows the curved cut weld and the characteristic image extracted by the corresponding optical sensor.

Figure 7 is a schematic diagram and characteristic changes of the tracking imaging laser at the corresponding position of the biological tissue weld.

Figure 8 shows the path planning laser scanning path modes, (a) linear type, (b) zigzag type, (c) segmented type.

Detailed ways

An in vitro laser biological tissue welding seam tracking device and method thereof according to the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

Write an example based on the shape of the weld path

As shown in Figure 3, the present invention uses an in vitro laser biological tissue welding seam tracking device, which includes:

A multi-beam laser parallel scanning emission device; a laser generator and a laser beam splitter; the laser beam splitter divides a laser into multiple beams;

The laser beam splitting device is equipped with a photonic crystal fiber beam splitter and a focusing mirror, and the beams of each channel are emitted in parallel; the beam splitting mirror can be adjusted according to the number of laser beams, and the distance between the beams can be adjusted;

The laser beam splitter contains a beam number adjusting device to adjust the number n of beams.

The n is 1 to 3.

Optical filters include brackets and filters; among them, the filters are used to filter interference light, improve imaging quality and accuracy, and thereby improve recognition capabilities.

Optical sensing device; mainly includes a visual sensing system composed of CCD cameras.

The above-mentioned in vitro laser biological tissue welding seam tracking device and laser beam splitter can change the distance between the beams obtained after splitting by adjusting the laser beam splitter; the laser beam splitter is equipped with a light shielding plate. Can block unnecessary beams and adjust the number of beams;

As described above, in an in vitro laser biological tissue welding seam tracking device, the filter in the optical filter is a broadband filter, and the transmittance of ultraviolet rays in the wavelength band of 200-380nm and infrared rays greater than 700nm is less than 3 *10 ^-4 .

The present invention adopts the imaging laser arrangement as shown in Figure 1, and the device system structure is shown in Figure 2, in which the optical signal transmission path required for welding seam tracking is shown in Figure 3.

Example 1

Using the above device, the biological tissue is welded using the in vitro laser biological tissue welding seam tracking method. Pig skin is selected as the sample. Its size is 30mm × 30mm × 4mm. It is composed of epidermal layer and dermal layer, and contains 0.5mm thick subcutaneous layer. Fat layer, incision shape is straight line. The laser welding process parameters corresponding to pigskin are shown in Table 1.

Table 1 Pigskin laser welding process parameters

Wavelength/nm Power/W Spot diameter/μm Welding speed mm/s Welding time/s 1064 4 35.5 100 1200

The in vitro laser biological tissue welding seam tracking method is used for incision welding. At the same time, the camera senses the optical properties of the biological tissue and automatically matches the appropriate welding process parameters. By controlling the parameter matching of the laser process, different types of biological tissues can be welded. The imaging laser irradiates the incision and uses image feature recognition to monitor the weld formation in real time during the welding process, and collects temperature data through a thermal imager. If the temperature exceeds the protein denaturation temperature of 60°C, feedback adjustment will automatically reduce the laser power and control thermal damage. Achieve high-quality welding.

Using an in vitro laser biological tissue welding seam tracking method according to the present invention, the specific steps are:

Step 1: Set the corresponding emissivity according to the physical and optical characteristics of the target biological tissue, and determine the required number of laser beams n=2 according to the length of the weld;

Step 2: Select the appropriate laser beam spacing s = 2.5mm according to the shape, trajectory and length of the welded cut;

Step 3: Start the optical sensing device, open the welding seam tracking software, and obtain optical images;

Step 4: Based on the optical characteristics of the biological tissue obtained by the optical sensor, the software automatically matches the corresponding welding process parameters in the database, and turns on the welding light source for welding;

Step 5: Based on the real-time image obtained by the optical sensing device, the software uses an image recognition algorithm to find the characteristic points of the weld, thereby identifying the starting point of the weld, and adjusts the position information of the corresponding solder point according to the change in the shape of the weld during the welding process. It is transmitted to the robotic arm to achieve real-time feedback adjustment. When the characteristics of the welding end point are extracted from the image, the laser is turned off and the welding is completed. The adaptive welding parameters as mentioned above are determined according to the optical properties of the target biological tissue, such as reflection coefficient and transmission coefficient.

Example 2

Using the above device, the biological tissue is welded using the in vitro laser biological tissue welding seam tracking method. The shape of the biological tissue incision is shown in Figure 5. The incision is an irregular curve and is welded with appropriate process parameters.

Using an in vitro laser biological tissue welding seam tracking method according to the present invention, the specific steps are:

Step 1, turn on the tracking laser, select the required number of laser beams n = 3 according to the length and shape of the welding seam, and select the appropriate laser beam spacing s = 1.5mm according to the shape, trajectory and length of the welded incision;

Step 2: Turn on the optical sensor and match the process parameters. Based on the obtained image information, when the continuous straight line changes into an image with a breakpoint offset in the middle, the software will give the welding laser a signal to start welding, and at the same time transmit the breakpoint position information. The robot arm can modify the laser welding position according to the image information in real time to achieve weld tracking; and because there are multiple imaging lasers, the position information obtained by the front-end laser imaging will be processed in advance, reducing the impact on the system due to drastic changes in the shape of the weld. The reaction time brought about; when the deformation and shrinkage caused by tissue dehydration and protein denaturation during the welding process changes the shape and position of the weld, the laser tracking system will correct it in real time.

Step 3: When the software in the industrial computer recognizes the characteristic points of the weld seam, it continues to be in the welding state. When it recognizes that the image changes from a breakpoint straight line to a continuous straight line, it is regarded as the welding end feature point, and the laser is turned off to stop welding.

Claims (2)

1. An isolated laser biological tissue welding self-adaptive path planning device, which is characterized by comprising:

the multi-beam laser parallel scanning emission device is provided with a laser generator and a laser beam splitter; the laser beam splitter divides one laser into a plurality of beams;

the laser beam splitter emits the light beam in parallel; the beam splitters can be adjusted according to the number of laser beams, and the distance interval between the laser beams is adjusted;

the laser beam splitter is internally provided with a light beam number adjusting device for adjusting the number n of light beams;

n is 1-3;

the optical filter is also provided with a bracket and an optical filter; the optical filter is used for filtering interference light, so that imaging quality and accuracy are improved, and identification capacity is further improved;

the optical sensing device is a visual sensing system consisting of CCD cameras;

extracting the characteristic value according to the superimposed image by a computer, judging the position of the welding line, drawing a space model according to the three-dimensional coordinates of the biological tissue obtained by laser ranging, and planning a path;

the laser beam splitter changes the distance between the light beams obtained after light splitting by adjusting the photonic crystal fiber; a light shielding plate is arranged in the laser beam splitter, so that unnecessary light beams can be shielded, and the number of the light beams can be regulated;

the optical filter is a broadband filter, and the transmittance of ultraviolet rays with the wavelength of 200-380nm and infrared rays with the wavelength of more than 700nm is less than 3 x 10 ^-4 ；

The optical sensing device is connected with the computer, automatically corrects the welding laser position in real time through software image processing, and transmits the welding spot position change information to the mechanical arm in a programming way;

in the laser scanning process, the moving interval is 2mm.

2. An in-vitro laser biological tissue welding seam self-adaptive path planning method based on the device of claim 1, which is characterized by comprising the following steps:

step 1, setting corresponding emissivity according to physical and optical characteristics of target biological tissues, and determining the number n of required laser beams according to the length of a welding line;

step 2, adjusting a laser beam splitter according to the length of a welded notch to obtain a proper laser beam spacing s, wherein s is more than or equal to 1mm and less than or equal to 3mm, and n multiplied by s is more than or equal to 3 and less than or equal to 5;

step 3, starting an optical sensing device to obtain an optical image; scanning welding lines by laser, wherein the moving interval is 2mm;

step 4, according to the optical characteristics of the biological tissue obtained by the optical sensor, the welding database software automatically searches and matches the corresponding welding process parameters in the database, and a welding indication red light source is turned on to wait for welding;

step 5, searching characteristic points in Matlab through an image recognition algorithm according to the real-time image obtained by the optical sensing device, and identifying a welding starting point: overlapping the acquired laser and natural light images in time and space dimensions, enhancing the identifiable degree of the welding seam in the images, improving the identifying precision of the welding seam, and reducing unnecessary thermal damage caused by overlarge laser scanning area in the biological tissue welding process; the method comprises the following steps:

extracting laser line distortion points from the superimposed images, extracting gray characteristic values of shadows of the welding seam area under natural light conditions, and superimposing the extracted gray characteristic values and the gray characteristic values to generate recognized three-dimensional coordinate data of the welding seam;

scanning and ranging the biological tissue by laser to obtain three-dimensional space coordinate points of each region, generating a biological tissue data model, superposing weld seam data, and carrying out path planning filling on the weld seam data according to the shape of the weld seam, wherein the paths comprise a zigzag path, a straight path and a segmented path;

when the image is recognized to be changed from a breakpoint straight line to a continuous straight line, the image is regarded as a welding end characteristic point, and the laser is turned off to finish welding;

the number n of the laser beams is 1-3;

in the step 1, self-adaptive welding parameters are determined according to optical characteristics of target biological tissues, reflection coefficients and transmission coefficients;

when the continuous straight line is changed into an image with break point offset in the middle, a signal for starting welding by welding laser is given, and meanwhile, the break point position information is transmitted to a mechanical arm, so that the laser welding position is modified in real time according to the image information, and the weld tracking is realized; the position information obtained by imaging the forefront laser can be processed in advance due to the fact that a plurality of imaging lasers are arranged, and reaction time brought to a system due to severe change of the shape of a welding line is reduced; when the welding process is performed, the deformation and shrinkage of the welding seam are caused by the dehydration of tissues and the denaturation of proteins, so that the shape and the position of the welding seam are changed, and the laser tracking system is corrected in real time.