阅读说明：本技术 一种三维超声探头标定装置及标定三维超声探头的方法 (three-dimensional ultrasonic probe calibration device and method ) 是由 杨敏 么娆 于 2019-08-16 设计创作，主要内容包括：本发明涉及一种三维超声探头标定装置及标定三维超声探头的方法,其中,三维探头标定装置包括光学定位仪、光学定位探针、超声无损探伤仪、标定模板、计算机和机械臂,光学定位仪和超声无损探伤仪分别与计算机连接,光学定位探针固定在超声无损探伤仪上,标定模板为内底部设有多个圆台的水槽,且多个圆台的顶面中心均开设有沉孔。与现有技术相比,本发明基于光学定位,提出了一种改进的标定模板,通过跟踪获取光学定位探针的姿态和位姿信息、采用机械臂夹持超声无损探伤仪进行超声图像扫描,以及直接由光学定位探针接触点目标获取点目标位置信息,减小了标定过程的操作难度,避免了对模板点目标位置信息的额外标定,提高了标定精度和效率。(The invention relates to a three-dimensional ultrasonic probe calibration device and a method for calibrating a three-dimensional ultrasonic probe, wherein the three-dimensional probe calibration device comprises an optical position finder, an optical positioning probe, an ultrasonic nondestructive flaw detector, a calibration template, a computer and a mechanical arm, wherein the optical position finder and the ultrasonic nondestructive flaw detector are respectively connected with the computer, the optical positioning probe is fixed on the ultrasonic nondestructive flaw detector, the calibration template is a water tank with a plurality of round tables at the inner bottom, and counter bores are formed in the centers of the top surfaces of the round tables. Compared with the prior art, the invention provides an improved calibration template based on optical positioning, and the invention obtains the attitude and pose information of an optical positioning probe by tracking, adopts a mechanical arm to clamp an ultrasonic nondestructive inspection instrument for ultrasonic image scanning, and directly obtains the point target position information by the optical positioning probe contact point target, thereby reducing the operation difficulty in the calibration process, avoiding the additional calibration of the template point target position information and improving the calibration precision and efficiency.)

1. a three-dimensional ultrasonic probe calibration device is characterized by comprising an optical position finder, an optical positioning probe, an ultrasonic nondestructive flaw detector, a calibration template, a computer and a mechanical arm, wherein the optical position finder and the ultrasonic nondestructive flaw detector are respectively connected with the computer, the optical positioning probe is fixed on the ultrasonic nondestructive flaw detector, the calibration template is a water tank with a plurality of round tables at the inner bottom, counter bores are formed in the centers of the top surfaces of the round tables, and the optical position finder is used for tracking and acquiring the position and posture information of the optical positioning probe;

The ultrasonic nondestructive flaw detector is used for scanning the calibration template to obtain an ultrasonic image;

The computer is used for processing the position and posture information of the ultrasonic image and the optical positioning probe so as to obtain a conversion relation between an ultrasonic image coordinate system and an optical positioning probe coordinate system;

The mechanical arm is used for clamping the ultrasonic nondestructive flaw detector to enable the ultrasonic nondestructive flaw detector to move according to the position of the preset track.

2. The three-dimensional ultrasonic probe calibration device according to claim 1, wherein the axes of the plurality of circular truncated cones are located on the same vertical plane and in an equidistant parallel relationship, and the plurality of circular truncated cones have the same size.

3. the three-dimensional ultrasonic probe calibration device according to claim 1, wherein the diameter of the counter bore is equal to the diameter of the needle of the optical positioning probe, and the depth of the counter bore is equal to the length of the needle of the optical positioning probe.

4. The three-dimensional ultrasonic probe calibration device according to claim 1, wherein the optical positioning probe is provided with an infrared reflection ball, and the optical position finder transmits infrared light to the optical positioning probe, and uses reflection information of the infrared reflection ball to track and acquire position and posture information of the optical positioning probe.

5. The calibration device of the three-dimensional ultrasonic probe according to claim 1, wherein the optical position finder is connected with the computer through a signal transmission line, and the ultrasonic nondestructive flaw detector is connected with the computer through a signal transmission line and an image acquisition card.

6. A method for calibrating a three-dimensional ultrasonic probe by using the three-dimensional ultrasonic probe calibration device of any one of claims 1 to 5, which is characterized by comprising the following steps:

s1, clamping the ultrasonic nondestructive inspection instrument fixed with the optical positioning probe above the calibration template by the mechanical arm, acquiring ultrasonic images of all round tables in the calibration template, tracking and acquiring the position and posture information of the optical positioning probe by the optical positioning instrument, and transmitting the ultrasonic images and the position and posture information of the optical positioning probe to a computer;

S2, the computer performs feature extraction and image segmentation on the ultrasonic image to obtain the position information of all the circular truncated cones under the ultrasonic image coordinate system, and meanwhile, the computer performs calculation processing on the position and posture information of the optical positioning probe to obtain a conversion matrix of the optical positioning probe coordinate system and the optical positioning instrument coordinate system;

s3, according to the preset track, the mechanical arm clamps the ultrasonic nondestructive flaw detector to sequentially raise by a preset distance for N times, and the distance is raised by one time per liter, and then the steps S1 and S2 are repeated to obtain the position information of all circular truncated cones of the ultrasonic nondestructive flaw detector under the ultrasonic image coordinate system at the height, and the conversion matrix of the optical positioning probe coordinate system and the optical position finder coordinate system;

s4, independently and sequentially inserting the optical positioning probes into the counter bores of all round tables in the calibration template, tracking the optical positioning probes through the optical positioning instrument, and acquiring the position information of all round tables under the coordinate system of the optical positioning instrument;

And S5, combining the position information of all the circular tables under the coordinate system of the optical positioning instrument and the position information of all the circular tables under the coordinate system of the ultrasonic image of the ultrasonic nondestructive flaw detector under the N +1 heights, and the conversion matrix of the coordinate system of the optical positioning probe and the coordinate system of the optical positioning instrument, and calculating to obtain the conversion matrix of the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe, namely the conversion relation between the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe.

7. a method of calibrating a three-dimensional ultrasound probe according to claim 6, wherein the optical position finder coordinate system is a three-dimensional world coordinate system, the optical positioning probe coordinate system is a three-dimensional coordinate system, the ultrasound image coordinate system is a two-dimensional coordinate system, and the transformation matrix of the optical positioning probe coordinate system and the optical position finder coordinate system is:

wherein, alpha _p, beta _p and gamma _p are attitude information of the optical positioning probe, and p _x, p _y and p _z are position information of the optical positioning probe.

8. the method of claim 7, wherein the transformation matrix of the ultrasound image coordinate system and the optical positioning probe coordinate system is:

the method comprises the following steps that P ^I is position information of all circular tables under N +1 heights in an ultrasonic image coordinate system, P ^W is position information of all the circular tables under an optical locator coordinate system, alpha _i, beta _i and gamma _i are rotation parameters of a conversion matrix T _P←I, and i _x, i _y and i _z are translation parameters of a conversion matrix T _P←I.

Technical Field

the invention relates to the technical field of ultrasonic probe positioning, in particular to a three-dimensional ultrasonic probe calibration device and a method for calibrating a three-dimensional ultrasonic probe.

Background

three-dimensional ultrasound imaging, which is a safe, inexpensive, and easy-to-operate non-destructive inspection technique, scans and records images of an object using a three-dimensional ultrasound probe, and then reconstructs and visualizes a 3D volume of the object. The calibration of the three-dimensional ultrasound probe is a key step for realizing 3D visualization of an ultrasound image, the spatial accuracy of an ultrasound system mainly depends on the accuracy of an ultrasound scanning plane relative to a probe marking coordinate system, the three-dimensional ultrasound imaging system usually needs to use the ultrasound probe to image on a template, and identify the characteristics of the ultrasound image, so as to minimize residual errors between characteristic sets identified in the image and on the template to optimize unknown spatial transformation parameters, and then obtain the corresponding 3D spatial geometric position.

the template based on the point model is one of the widely used models at present due to the advantages of simplicity, easiness in construction, accuracy in imaging and the like, but the defect is that an ultrasonic plane and a target point need to be coplanar, so that the existing probe calibration process based on the point model is generally monotonous and time-consuming, and has higher requirements on operators. The traditional point model generally uses round beads or cross lines to form a single-point or multi-point target, so the position of the point target cannot be directly known, the point target needs to be scanned at a plurality of angles, the number of required imaging images is large, an operator needs to hold an ultrasonic flaw detector by hand and repeatedly image a cross point, then the transformation parameter from an ultrasonic image coordinate system to a probe coordinate system is iteratively solved, otherwise the transformation parameter is not accurate due to high constraint of an optimization process, however, the ultrasonic image scanning is carried out by depending on the ultrasonic flaw detector by hand, the operation stability and the imaging definition cannot be ensured, in addition, the iteration method is adopted to solve the coordinate transformation parameter, the position information of a template needs to be calibrated in advance, and the introduction of errors is caused.

Therefore, it is an urgent need to solve the problem in the current three-dimensional ultrasound probe positioning technology to improve the existing template based on the point model, and design a calibration device and a calibration method that do not depend on manual repeated operation, can conveniently and rapidly complete calibration, and do not need to image at multiple viewing angles, so as to improve the precision and efficiency of the three-dimensional ultrasound probe calibration.

disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a three-dimensional ultrasonic probe calibration device and a method for calibrating a three-dimensional ultrasonic probe.

The purpose of the invention can be realized by the following technical scheme: a three-dimensional ultrasonic probe calibration device comprises an optical position finder, an optical positioning probe, an ultrasonic nondestructive flaw detector, a calibration template, a computer and a mechanical arm, wherein the optical position finder and the ultrasonic nondestructive flaw detector are respectively connected with the computer, the optical positioning probe is fixed on the ultrasonic nondestructive flaw detector, the calibration template is a water tank with a plurality of round tables at the inner bottom, counter bores are formed in the centers of the top surfaces of the round tables, and the optical position finder is used for tracking and acquiring the position and posture information of the optical positioning probe;

the ultrasonic nondestructive flaw detector is used for scanning the calibration template to obtain an ultrasonic image;

The computer is used for processing the position and posture information of the ultrasonic image and the optical positioning probe so as to obtain a conversion relation between an ultrasonic image coordinate system and an optical positioning probe coordinate system;

The mechanical arm is used for clamping the ultrasonic nondestructive flaw detector to enable the ultrasonic nondestructive flaw detector to move according to the position of the preset track.

Preferably, the axes of the plurality of circular truncated cones are located on the same vertical plane and in an equidistant parallel relationship, and the plurality of circular truncated cones have the same size.

preferably, the diameter of the counter bore is equal to the diameter of the needle head of the optical positioning probe, and the depth of the counter bore is equal to the length of the needle head of the optical positioning probe.

preferably, the optical positioning probe is provided with an infrared reflection ball, the optical positioning instrument transmits infrared light to the optical positioning probe, and the position and posture information of the optical positioning probe is tracked and acquired by using the reflection information of the infrared reflection ball.

Preferably, the optical position finder is connected with the computer through a signal transmission line, and the ultrasonic nondestructive flaw detector is connected with the computer through a signal transmission line and an image acquisition card.

A method for calibrating a three-dimensional ultrasonic probe by using a three-dimensional ultrasonic probe calibration device comprises the following steps:

S1, clamping the ultrasonic nondestructive inspection instrument fixed with the optical positioning probe above the calibration template by the mechanical arm, acquiring ultrasonic images of all round tables in the calibration template, tracking and acquiring the position and posture information of the optical positioning probe by the optical positioning instrument, and transmitting the ultrasonic images and the position and posture information of the optical positioning probe to a computer;

S2, the computer performs feature extraction and image segmentation on the ultrasonic image to obtain the position information of all the circular truncated cones under the ultrasonic image coordinate system, and meanwhile, the computer performs calculation processing on the position and posture information of the optical positioning probe to obtain a conversion matrix of the optical positioning probe coordinate system and the optical positioning instrument coordinate system;

s3, according to the preset track, the mechanical arm clamps the ultrasonic nondestructive flaw detector to sequentially raise by a preset distance for N times, and the distance is raised by one time per liter, and then the steps S1 and S2 are repeated to obtain the position information of all circular truncated cones of the ultrasonic nondestructive flaw detector under the ultrasonic image coordinate system at the height, and the conversion matrix of the optical positioning probe coordinate system and the optical position finder coordinate system;

S4, independently and sequentially inserting the optical positioning probes into the counter bores of all round tables in the calibration template, tracking the optical positioning probes through the optical positioning instrument, and acquiring the position information of all round tables under the coordinate system of the optical positioning instrument;

And S5, combining the position information of all the circular tables under the coordinate system of the optical positioning instrument and the position information of all the circular tables under the coordinate system of the ultrasonic image of the ultrasonic nondestructive flaw detector under the N +1 heights, and the conversion matrix of the coordinate system of the optical positioning probe and the coordinate system of the optical positioning instrument, and calculating to obtain the conversion matrix of the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe, namely the conversion relation between the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe.

preferably, the optical positioning instrument coordinate system is a three-dimensional world coordinate system, the optical positioning probe coordinate system is a three-dimensional coordinate system, the ultrasonic image coordinate system is a two-dimensional coordinate system, and a transformation matrix between the optical positioning probe coordinate system and the optical positioning instrument coordinate system is:

wherein, alpha _p, beta _p and gamma _p are attitude information of the optical positioning probe, and p _x, p _y and p _z are position information of the optical positioning probe.

Preferably, the transformation matrix of the ultrasound image coordinate system and the optical positioning probe coordinate system is:

the method comprises the following steps that P ^I is position information of all circular tables under N +1 heights in an ultrasonic image coordinate system, P ^W is position information of all the circular tables under an optical locator coordinate system, alpha _i, beta _i and gamma _i are rotation parameters of a conversion matrix T _P←I, and i _x, i _y and i _z are translation parameters of a conversion matrix T _P←I.

compared with the prior art, the invention has the following advantages:

The invention provides an improved calibration template, a plurality of point targets with the same size are arranged on the same straight line, the structure is simple, the operation difficulty is reduced, multi-angle scanning imaging is not needed, in addition, an ultrasonic nondestructive flaw detector is clamped by a mechanical arm to carry out ultrasonic image scanning, compared with the traditional handheld scanning method, the stability and imaging definition during scanning are ensured, and the calibration efficiency and accuracy can be effectively improved.

The optical positioning probe is directly contacted with the point target, and the position information of the point target under the world coordinate system is sequentially obtained, so that the additional calibration of the position information of the template point target is avoided, and the error introduction in the iterative solution process is reduced.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic structural diagram of a calibration template in the embodiment;

FIG. 3 is a flow chart of a method of the present invention;

the notation in the figure is: 1. the system comprises an optical locator, 2, an ultrasonic nondestructive flaw detector, 3, an optical positioning probe, 4, a computer, 5 and a calibration template.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

As shown in fig. 1 and 2, a three-dimensional ultrasonic probe calibration device includes an optical locator 1, an optical positioning probe 3, an ultrasonic nondestructive flaw detector 2, a calibration template 5, a computer 4 and a mechanical arm 6, wherein the optical locator 1 and the ultrasonic nondestructive flaw detector 2 are respectively connected with the computer 4, the optical positioning probe 3 is fixed on the ultrasonic nondestructive flaw detector 2, the calibration template 5 is a water tank with a plurality of circular truncated cones at the inner bottom, and the optical locator 1 is used for tracking and acquiring position and posture information of the optical positioning probe 3;

The ultrasonic nondestructive flaw detector 2 is used for scanning the calibration template 5 to obtain an ultrasonic image;

The computer 4 is used for processing the ultrasonic image and the position and posture information of the optical positioning probe 3 to obtain a conversion relation between an ultrasonic image coordinate system and an optical positioning probe coordinate system;

The mechanical arm 6 is used for clamping the ultrasonic nondestructive inspection instrument 2, so that the ultrasonic nondestructive inspection instrument 2 moves according to a preset track.

In the embodiment, an optical position finder 1 is fixed by a support and is connected to a computer 4 through a signal transmission line, an ultrasonic nondestructive flaw detector 2 is connected to the computer 4 through a signal line and an image acquisition card, an optical positioning probe 3 is fixed on the ultrasonic nondestructive flaw detector 2 through rigid connection, four infrared reflection balls are arranged on the optical positioning probe 3, the optical position finder 1 transmits infrared light to the optical positioning probe 3, and the position and posture information of the optical positioning probe 3 is tracked and acquired by utilizing the reflection information of the infrared reflection balls;

as shown in fig. 2, the calibration template 5 is a water tank with five circular truncated cones arranged at the bottom, in order to clearly image all characteristic points in an ultrasonic imaging plane, the five circular truncated cones have the same size and have axes parallel to each other at equal intervals on the same plane, the interval between each circular truncated cone is fixed to be 22.5mm, the diameter of the lower bottom of each circular truncated cone is 8mm, the diameter of the upper bottom is 1.5mm, and the height is 45mm, a counter bore with the diameter of 0.6mm and the depth of 0.3mm is arranged at the center of the top surface of each circular truncated cone to serve as a point target of the calibration template 5, the size of the counter bore is consistent with the size of the needle head of the optical positioning probe 3, and the function is that before calibration, the needle head of the optical positioning probe 3 directly contacts the counter bore to obtain the position information of the five target characteristic points under the coordinate system of the;

The ultrasonic imaging target characteristic point is a counter bore positioned at the centers of circles of the five circular truncated cones and can be regarded as five collinear point targets, the ultrasonic nondestructive inspection instrument 2 is clamped by the mechanical arm 6 to replace a handheld ultrasonic probe, the mechanical arm 6 is driven to a proper position, so that the five characteristic point targets are clearly imaged in an ultrasonic image, the mechanical arm 6 is adjusted to change the position of the ultrasonic nondestructive inspection instrument 2 so as to acquire the ultrasonic image at different depths, the computer 4 obtains pixel coordinate values of five target points under an ultrasonic image coordinate system through image segmentation and extraction algorithms, meanwhile, the optical locator 1 stores the position information of the ultrasonic nondestructive inspection instrument 2 into the computer 4 and processes the pixel coordinate values to obtain a conversion matrix, then the needle heads of the optical positioning probes 3 are respectively contacted with the counter bores at the centers of the five circular truncated cones, and simultaneously the position information of the optical positioning probes 3 is recorded and stored into the computer 4, calculating to obtain a three-dimensional coordinate value of the characteristic point under a coordinate system (namely a world coordinate system) of the optical position indicator; and finally, the computer 4 constructs an objective function according to all the data and obtains a required calibration matrix by adopting an optimization algorithm.

Fig. 3 shows a method for calibrating a three-dimensional ultrasonic probe by using the device, which comprises the following steps:

s1, clamping the ultrasonic nondestructive inspection instrument 2 fixed with the optical positioning probe 3 above the calibration template 5 by the mechanical arm 6, acquiring ultrasonic images of all round tables in the calibration template 5, tracking and acquiring the position and posture information of the optical positioning probe 3 by the optical positioning instrument 1, and transmitting the ultrasonic images and the position and posture information of the optical positioning probe 3 to the computer 4;

s2, the computer 4 performs feature extraction and image segmentation on the ultrasonic image to obtain the position information of all the circular truncated cones under the ultrasonic image coordinate system, and meanwhile, the computer 4 performs calculation processing on the position and posture information of the optical positioning probe 3 to obtain a conversion matrix of the optical positioning probe coordinate system and the optical positioning instrument coordinate system;

S3, according to the preset track, the mechanical arm 6 clamps the ultrasonic nondestructive flaw detector 2 to sequentially increase by N times according to the preset distance, and if the distance is increased by one preset distance per liter, the steps S1 and S2 are repeated to obtain the position information of all circular truncated cones of the ultrasonic nondestructive flaw detector 2 under the ultrasonic image coordinate system at the height and the conversion matrix of the optical positioning probe coordinate system and the optical position finder coordinate system;

S4, independently and sequentially inserting the optical positioning probes 3 into the counter bores of all round tables in the calibration template 5, tracking the optical positioning probes 3 through the optical positioning instrument 1, and acquiring the position information of all round tables in the coordinate system of the optical positioning instrument;

And S5, combining the position information of all the circular truncated cones under the coordinate system of the optical positioning instrument and the position information of all the circular truncated cones under the coordinate system of the ultrasonic image and the transformation matrix of the coordinate system of the optical positioning probe and the coordinate system of the optical positioning instrument under the N +1 heights of the ultrasonic nondestructive inspection instrument 2, and calculating to obtain the transformation matrix of the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe, namely the transformation relation between the coordinate system of the ultrasonic image and the coordinate system of the optical positioning probe.

the conversion matrix of the optical positioning probe coordinate system and the optical positioning instrument coordinate system is as follows:

In the formula, alpha _p, beta _p and gamma _p are attitude information of the optical positioning probe, and p _x, p _y and p _z are position information of the optical positioning probe;

The transformation matrix of the ultrasonic image coordinate system and the optical positioning probe coordinate system is as follows:

in the formula, P ^I is the position information of all the circular truncated cones under the N +1 heights in the ultrasound image coordinate system, P ^W is the position information of all the circular truncated cones under the optical locator coordinate system, α _i, β _i and γ _i are the rotation parameters of the transformation matrix T _P←I, and i _x, i _y and i _z are the translation parameters of the transformation matrix T _P←I.

in this embodiment, the preset distance for each time of raising of the ultrasonic nondestructive inspection apparatus 2 is 5mm, and the raising is performed for 5 times in total, and the specific calibration process in the embodiment of the method of the present invention is as follows:

injecting water submerging the surface of a circular truncated cone into a calibration template 5, fixing an optical positioning probe 3 on an ultrasonic nondestructive inspection instrument 2, fixedly placing an optical positioning instrument 1 for tracking the posture and position information of the optical positioning probe 3 by a support, clamping and driving the ultrasonic nondestructive inspection instrument 2 to be above five circular truncated cones through a mechanical arm 6, scanning the calibration template 5 to obtain a clear ultrasonic image containing five characteristic points, simultaneously acquiring and storing the ultrasonic image by a computer 4 and recording the posture and position information of the optical positioning probe 3 at the moment, and processing by the computer 4 to obtain the pixel coordinates of the five characteristic points in the ultrasonic image under an ultrasonic image coordinate system, and a position conversion matrix of the optical positioning probe coordinate system and an optical positioning instrument coordinate system;

^I _W←PThe mechanical arm 6 is driven to enable the ultrasonic nondestructive flaw detector 2 to be lifted by 5mm, imaging is carried out at a new height level, the attitude and the position information of the ultrasonic image and the positioning probe 3 are stored, and the pixel coordinates of five characteristic points at the new height position under an ultrasonic image coordinate system, the position conversion matrix of the optical positioning probe coordinate system and the optical positioning instrument coordinate system are obtained through processing of the computer 4;

Finally, under the condition that the position of the calibration template 5 is fixed, the optical positioning probe 3 is used for respectively contacting the counter bores on the upper surfaces of the five circular truncated cones in the calibration template 5, the position information of the five characteristic points in the coordinate system of the optical positioning instrument is sequentially obtained, namely the position information P ^W of the five characteristic points in the world coordinate system, a calibrated conversion matrix T _P←I can be obtained through calculation by constructing an objective function P ^W which is T _W←P. T _P←I. P ^I, and the conversion calibration of the ultrasonic image coordinate system and the optical positioning probe coordinate system is completed.

In conclusion, compared with the traditional calibration method, the three-dimensional ultrasonic probe calibration device based on optical positioning improves the calibration precision and accuracy, has less scanning times, does not need to generate a plurality of ultrasonic images, simplifies the calibration process, is simple and quick to operate, reduces the introduction of errors, shortens the calibration time, and can lay a reliable data foundation for the subsequent three-dimensional reconstruction.