CN100571606C - A kind of microrobot and external guidance system thereof - Google Patents

Abstract

A kind of microrobot and external guidance system thereof, fuselage [1a] internal placement has permanent magnet block [1b], micromotor [1f], radio frequency receiver [1d], minicell [1e], afterbody rotating mechanism [1h] forms a fixed connection by the swingle that stretches out in the through hole of fuselage [1a] rear end with afterbody [1i], and swingle and fuselage [1a] adopt the sealing of high resiliency diaphragm seal.The external alignment control system of microrobot, treat search coverage by imaging subsystems [6] and carry out continuous sweep, the gained raw image data is admitted to computer control subsystem [7] and carries out image reconstruction, magnetic orientation subsystem [5] carries out magnetic orientation to the inner permanent magnet block [1b] of microrobot [1], the gained original position-information is admitted to computer control subsystem [5] and carries out the position reconstruction, computer control subsystem [5] produces the guiding control information and also is passed to magnetic steering subsystem [4], and magnetic steering subsystem [4] is to microrobot [1] control of leading.

Description

A kind of micro-robot and its external guidance system

technical field

The invention relates to the technical field of bionic micro-robots, in particular to a micro-robot and an in vitro guidance system thereof.

Background technique

With the development of robot technology and micro-electro-mechanical systems, micro-robots have become a research hotspot at home and abroad, especially the development and application of wireless endoscopes that enter the human body, vascular robots, and micro-robots for the detection of small pipelines in industrial equipment. are especially valued. Due to the special working environment, this type of micro-robot cannot be a simple miniaturization of ordinary robots, especially in the way of driving will be very different from ordinary robots. At present, the driving methods of micro-robots can be roughly divided into two categories: one is driven by the actuator of the robot body; The actuator realizes wireless drive through external field excitation.

For the driving mode of body actuators, most of them adopt bionic driving mode. For example, D.Reynaerts imitated the inchworm to make a robot model for digestive tract inspection, S.Hirose designed a snake-like robot, and Zhou Yinsheng of Zhejiang University proposed a snail-like and bionic robot. Tadpole robot, Mei Tao, Hefei Institute of Intelligent Machinery, Chinese Academy of Sciences, etc. proposed a gecko-like crawling robot, and Yan Guozheng, Shanghai Jiaotong University, etc. developed a miniature hexapod bionic robot. Because the working environment has strict requirements on the size of the robot, these bionic micro-robots currently have less controllable degrees of freedom. Generally speaking, there is no special attitude control, but it is realized by the natural constraints of pipelines or contact surfaces. Therefore, there will be certain damage to the contact surface, which is unfavorable for medical robots, and may even cause blockage in some places with large curvature. The research on external field driving methods is also relatively active. For example, T. Yasuda et al. have developed miniature ants driven by ultrasonic field, T. Fukuda et al. have made pipeline micro-robots driven by alternating magnetic field with giant magnetostrictive materials, K. Ishyama et al. made a micro-robot driven by a rotating magnetic field with a permanent magnet material wound with a helical metal wire. Mei Tao et al. studied a capsule endoscopic robot driven by an external magnetic field and the Institute of Electrical Engineering, Chinese Academy of Sciences. Wang Qiuliang and others have developed a magnetic navigation surgery model system with a permanent magnetic block driven by a uniform gradient magnetic field. The body of these robots does not require motors, nor does it require internal energy supply, so the size can be made very small, and some have achieved a diameter of less than 1.5mm, but they lack attitude control and poor flexibility. In many applications, it may be a better solution to combine the two driving methods. The movement form of magnetotactic bacteria in nature uses a similar method.

Magnetotactic bacteria are a type of bacteria with magnetotropic behavior. They contain single magnetic domain particles (magnetosomes) arranged in chains in their bodies, and spiral flagella driven by flagellar motors grow at the ends. In the natural environment, the geomagnetic field acts on the magnetosome chains to generate magnetic torque, forcing magnetotactic bacteria to orient along the geomagnetic field. The chemotaxis sensor in bacteria is a receptor complex protein responsible for sensing environmental changes—methyl chemoattractant protein, which can activate the flagellar motor to rotate the flagella counterclockwise and drive the bacteria to swim in a straight line along the direction of the geomagnetic field. The microaerobic environment in which it grows. In this way, magnetotactic bacteria use the geomagnetic field to simplify the search task in three-dimensional space to one-dimensional space search task. Studies have shown that this method greatly improves their search speed and search efficiency.

U.S. patents 5,337,732, 5,662,587, and 5,906,591 "snake or inchworm-like endoscopic robot" and Chinese patent 01126965.0 "hexapod bionic micro-robot" all adopt the drive method based on the body actuator. The above-mentioned U.S. patent "snake-like or inchworm endoscopic robot", the main body actuator is a multi-section interconnected joints in the robot body, including traction joints and excitation joints. By orderly controlling the movements of each joint, the robot can do things similar to The movement of snakes or inchworms. The above-mentioned Chinese patent "hexapod bionic micro-robot" mainly includes a frame, a micro-motor, a worm gear device, a belt drive, a four-bar mechanism, and a forefoot, a middle foot, and a rear foot. Electric motor, worm gear device, belt transmission device, four-bar mechanism and two forefoot, middle foot and rear foot are arranged outside the frame, the micro motor is connected with the worm gear device, and connected with the belt transmission device through the belt, the belt transmission device The axes of the four-bar mechanism are respectively connected with the four-bar mechanism, and the power is transmitted to the four-bar mechanism respectively, and the four-bar mechanism is respectively connected with the front foot, the middle foot and the rear foot, and drives the hexapod to walk. In the present invention, the robot body contains a micro battery, a radio frequency receiver, a micro motor, a tail rotation mechanism and a tail, and the computer controls the movement of the micro motor through a radio frequency transmitter to drive the tail rotation mechanism to make the robot move forward or backward.

Another type of patent involves external field-driven micro-robot technology, such as Chinese patent 200510040887.8 "In vivo detection of external magnetic field driving device and method" and Chinese patents 200410009485.7 and 200410009528.1. The external magnetic field driving technology involved in the above patents is to use the combined coil system to construct a relatively uniform gradient magnetic field (generated by normal or superconducting coils) in the space, and jointly control the magnitude of the loading current and the movement of some coils relative to the human body. The magnitude and direction of the gradient, the gradient magnetic field acts on the built-in magnetic body of the magnetic micro-robot to obtain the desired space vector force, and then realize the desired movement. In the present invention, the external guiding coil produces a uniform guiding magnetic field, forcing the built-in magnet of the magnetic micro-robot to deflect along the direction of the guiding magnetic field. From the perspective of the entire movement process, the micro-robot tends to move along the tangential direction of the pipeline extension, driving the micro-robot to move Energy is provided by devices such as micro-motors inside the micro-robot.

At present, medical robot technology is getting more and more attention. Due to the characteristics of the internal environment, it is difficult for traditional robots to play a role. Therefore, various bionic micro-robots have emerged as the times require. It has a shortpart.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of poor attitude control and movement flexibility in the existing micro-robot drive technology, learn from the movement mode of magnetotactic bacteria, and propose a bionic micro-robot with active helical propulsion combined with external magnetic field attitude control. its in vitro guidance system. To a certain extent, the invention solves the contradiction between the miniaturization of the volume of the robot and the flexibility of movement, and can play an important role in in vivo diagnosis and treatment and detection of non-magnetic small pipelines.

1. The function and structure of the micro-robot of the present invention are described as follows:

Driven by the external guiding magnetic field and the internal micro-motor, the micro-robot of the present invention deflects along the direction of the guiding magnetic field, and advances to a given target along the tangential direction of the pipeline extension, and can adjust the micro-motor through the radio frequency transmitting receiver under the control of the computer , to make the robot move forward and backward.

The micro-robot includes the following components: fuselage, permanent magnet block, micro-motor, radio-frequency receiver, micro-battery, tail rotating mechanism and tail.

The casing of the micro-robot is made into a capsule shape, with smooth ends and no protrusions or grooves in the middle. The surface is covered with smooth, tough and flexible medical materials to reduce friction with the inner wall of the pipeline. The interior of the fuselage is hollowed out. There is a spiral groove on the inner peripheral surface of the front end for fixing the permanent magnet block, and an axial through hole is opened on the bottom. The fuselage is made of two symmetrical materials. Two for one paste into one. The shape of the micro-motor is a cuboid, arranged in the fuselage. The tail rotation mechanism of the robot is used to drive the tail with a shape similar to the flagella of magnetotactic bacteria. The tail is made of medical materials with good flexibility. The tail is fixedly connected with the rotating rod protruding from the through hole of the fuselage, and a high elastic sealing film is used. Seal the swivel rod to the body. The radio frequency receiver is installed on the inner peripheral surface of the fuselage, and both the micro motor and the radio frequency receiver are powered by a micro battery installed in the fuselage.

The permanent magnet block is equivalent to the magnetosome chain in the magnetotactic bacteria, and has a magnetic moment, which will generate a magnetic torque under the action of an external guiding magnetic field, tending to the direction of the guiding magnetic field.

When the electrodes of the micro-motor are turned on in the forward direction, the micro-motor drives the tail rotating mechanism to rotate forwardly, and then drives the flexible tail to rotate forwardly periodically. Conversely, when the operator reversely connects the electrodes of the micro-motor under the control of the computer, the rotating rod will drive the tail to rotate in the reverse direction, and the environmental liquid will generate a backward axial thrust on the robot, causing the robot to retreat.

In the present invention, the computer generates the radio frequency transmission signal, which is received by the radio frequency receiver in the robot body to control the rotation direction and speed of the micro motor, and then combined with other external control devices to realize the control of the movement of the micro robot.

2. The in vitro guidance system of the miniature robot of the present invention includes a magnetic positioning subsystem, an imaging subsystem, a magnetic guidance subsystem and a computer control subsystem, wherein the computer control subsystem provides a human-computer interaction interface, and controls the magnetic positioning, imaging and magnetic guidance subsystems. The system realizes the control of the movement of the micro-robot. As the central console, the computer control subsystem connects the magnetic positioning subsystem, the imaging subsystem and the magnetic guiding subsystem respectively through the data bus and the control bus to control the working status of other subsystems and exchange data. The functions and working principles of each subsystem are described as follows:

2.1 Magnetic positioning subsystem

Without considering the external disturbance magnetic field, the function of this subsystem is to measure the change of the spatial distribution of the magnetic field of the permanent magnet block, and convert it into a current signal and provide it to the computer. The computer calculates the permanent magnet block through the inverse algorithm, namely The position of the micro-robot can achieve continuous position measurement. At the same time, combined with the relative position between the robot and the pipeline provided by the imaging subsystem in stages, the operator can obtain the relative position of the robot in real time through the computer.

This subsystem is mainly composed of 8 giant magnetoresistance (GMR) sensors, and the sensors are distributed on the 8 vertices of a virtual cuboid covering the outside of the pipeline under test. According to the magnetoresistance effect, the resistivity of the giant magnetoresistance can change with the change of the external magnetic field, and the current flowing in the resistance will change at a given voltage. According to the current change, the computer can use the magnetic positioning inversion algorithm to obtain the coordinates of the permanent magnet block.

The magnetic field excited by the permanent magnet block in its surrounding space has a specific distribution law, so the position of the permanent magnet block can be determined by detecting the change of the magnetic field. When the size of the permanent magnet block is much smaller than the distance between the detection point and the permanent magnet block, the permanent magnet block can be equivalent to a magnetic dipole, and its spatial magnetic field distribution model can be expressed by the following formula:

为磁偶极子的磁矩矢量，

为磁偶极子到检测点的矢径。 The magnetic permeability in

is the magnetic moment vector of the magnetic dipole,

is the vector radius from the magnetic dipole to the detection point.

2.2 Imaging subsystem

This subsystem adopts mature X-ray computed tomography imaging technology to perform three-dimensional imaging of the detection area. Considering that the pipeline may make small random movements, and the speed of obtaining the position information of the robot is quite different from the imaging speed, therefore, the imaging sub-system in this invention The system periodically images the pipeline and the robot, and each image is used to aid in the guidance of the robot's movement during the corresponding period. According to the principle of computerized tomography, the X-rays emitted by the X-ray source pass through the subject and project to the detector. The X-ray detector receives the projection data related to the local X-ray attenuation coefficient and sends it to the computer, and then the computer reconstructs the image The algorithm reconstructs the image of the subject, that is, the image of the pipeline and the robot, and can obtain the three-dimensional extension direction and size information of the pipeline.

This subsystem includes an X-ray source, a circular array of X-ray detectors, an imaging power supply, a moving bed, an interface circuit, and a display, wherein the circular array of X-ray detectors is located in a plane perpendicular to the axial direction of the moving bed, and the X-ray source is on the plane Circumferential scanning can be done inside, the imaging power supply is used to supply power to the X-ray source and the X-ray detector circular array, the interface circuit is used to receive the original image data and perform preprocessing such as filtering and format conversion, and then input it into the computer control subsystem for further processing The image is reconstructed and synthesized, and finally displayed on the monitor.

When working, the subject is placed on the moving bed, which can translate along its own axis and move slightly in the scanning plane so that the part to be imaged is located in the imaging area. The X-rays emitted by the X-ray source become a very narrow beam after being collimated. The X-ray source is in the scanning plane, and the geometric center of the imaging part is used as the center of the circle to scan the tomographic circle. This subsystem uses photodiodes as X-ray detectors, and several photodiodes are arranged on the scanning plane in the form of a circular array, concentric with the scanning circle, and the position of the array remains unchanged during the imaging process.

This subsystem is based on two-dimensional plane imaging, and realizes three-dimensional imaging of pipelines and robots by separately imaging and synthesizing multiple continuous slices, that is, it is necessary to use back projection reconstruction algorithm to obtain two-dimensional images. When imaging a slice, the slice to be imaged is first moved to the imaging area driven by the moving bed, and then the X-ray source performs a 360° circular scan at a constant angular velocity. After one week of scanning, the X-ray source returns to the initial position, and the next slice to be scanned is scanned after entering the scanning plane. After the specified parts are scanned, the computer uses image processing programs to process the original image data and reconstruct each tomographic image, and finally synthesize a three-dimensional image of the pipeline and the robot.

2.3 Magnetic Guidance Subsystem

With the cooperation of the moving bed, this subsystem can generate a uniform guiding magnetic field pointing to the desired direction in the central area, implement deflection guiding control on the permanent magnet block, and then realize the attitude control of the micro robot. The direction of the steering magnetic field is obtained by the magnetic steering algorithm, and the interface circuit sends the steering magnetic field signal to the magnetic steering subsystem power supply. According to the position of the robot measured by the magnetic positioning subsystem and the relative position between the pipeline and the robot provided by the imaging subsystem, the operator can give the moving direction of the micro robot in real time, which is realized by the guiding magnetic field acting on the permanent magnet block. Using the magnetic guidance algorithm, this subsystem can generate a guidance magnetic field along the desired direction according to the pose of the robot. The guiding magnetic field is obtained by passing an adjustable DC current through three sets of Helmholtz coils, that is, it is formed by superimposing three magnetic fields with two pairs of orthogonal directions in space. This method is simple to operate and can effectively control the attitude of the robot, making it easier to overcome some obstacles such as narrow space and turning when moving in the pipeline.

The process of the magnetic guidance algorithm includes: firstly, establish a unified coordinate system, establish a robot reference moving trajectory according to the pipeline extension image generated by the imaging subsystem, and select the central extension axis of the pipeline as the reference trajectory; within the effective time of the image, Replace the moving trajectory of the robot with a broken line connected by several discontinuous points. The discontinuous point is the position of the robot measured by the magnetic positioning subsystem; when determining the direction of the guiding magnetic field, when the scale of the robot is much smaller than that of the pipeline When the length of , the robot can be regarded as a mass point, assuming that the robot is located at p ₀ (x ₀ , y ₀ , z ₀ ) at time t=t ₀ , within the range allowed by the position resolution of the magnetic positioning subsystem, the elapsed time Δt, Δt →0, the micro-robot moves to point p ₁ (x ₁ , y ₁ , z ₁ ), and then finds a point on the reference trajectory, which is the orthogonal projection of p ₁ on the reference trajectory, and calculates The directional derivative of the tangent direction at the projected point on the trajectory, and the directional derivative from point p ₀ to p ₁ , the difference between the two directional derivatives is calculated by the program, and the difference is the time t=t ₀ +Δt required Direction correction value; finally, the direction correction value is converted into the control parameter of the guiding magnetic field, that is, the correction value of the current in the coil, and the computer transmits this correction value from the interface circuit to the magnetic guidance subsystem power supply unit, and finally generates the required guiding magnetic field .

的作用，

可表示为 $\stackrel{\mathrm{\ρ}}{T}=\stackrel{\mathrm{\ρ}}{P}\×\stackrel{\mathrm{\ρ}}{B},$ 式中

为磁矩，等于磁块的磁化强度矢量

在磁块体积上的积分，在数值上有P＝∫_vMdv，

为外部磁场的磁感应强度矢量。当磁块磁场的方向与外磁场正交时，力偶矩

最大。This subsystem is designed according to the principle of magnetic field force, that is, the magnet in the external magnetic field will be deflected under the action of force. In a uniform magnetic field, the permanent magnet block is subjected to a couple moment

role,

can be expressed as $\stackrel{\mathrm{\ρ}}{T}=\stackrel{\mathrm{\ρ}}{P}\×\stackrel{\mathrm{\ρ}}{B},$ In the formula

is the magnetic moment, which is equal to the magnetization vector of the magnetic block

The integral on the volume of the magnetic block has P= _∫v Mdv in value,

is the magnetic induction vector of the external magnetic field. When the direction of the magnetic field of the magnetic block is perpendicular to the external magnetic field, the moment of the couple

maximum.

i＝x，y，z，分别代表空间直角坐标系中的三个分量。对三个磁场分量做矢量叠加后，得到导向磁感应强度 This subsystem consists of three sets of mutually orthogonal Helmholtz coils and a power supply device, which can generate a uniform magnetic field in the central area. Each set of coils is composed of two pairs of circular coils parallel to each other. The distance between the two pairs of coils is equal to coil radius. By adjusting the coil current, the magnetic induction intensity of the guiding magnetic field It is continuously adjustable in value and direction. The power supply device receives the control parameters of the guiding magnetic field obtained by the computer, and adjusts the magnetic induction intensity generated by each group of coils

i=x, y, z represent three components in the space Cartesian coordinate system respectively. After vector superposition of the three magnetic field components, the guiding magnetic induction intensity is obtained

According to the Biot-Savart law, the magnetic field generated by the Helmholtz coil is

(2)

(2)

为线圈上微线元

所产生的磁场，

为微线元

相对于感兴趣位置的矢径。In the formula, I is the current intensity in the coil,

Microline element on the coil

The resulting magnetic field,

microline element

Radius relative to the location of interest.

2.4 Computer Control Subsystem

This subsystem is the signal processing and control center of the robot's external guidance system, and is composed of a computer and an interface circuit. The subsystem controls the moving speed and direction of the robot by cooperating with the magnetic positioning subsystem, imaging subsystem, magnetic guidance subsystem and radio frequency transceiver. Under the hybrid drive of active helical drive combined with external magnetic field attitude control, various control strategies can be realized, and the optimal control strategy can be found to make the robot move according to the desired trajectory.

This subsystem is connected to the magnetic positioning subsystem, the imaging subsystem and the magnetic guidance subsystem through the interface circuit, and is responsible for data processing and communication. The interface circuit mainly includes a piece of analog-to-digital converter AD9874, a piece of digital signal processor TMS320f2812, a piece of programmable logic device EPM7128AETC100-10 and a piece of digital-to-analog converter DAC7625. The analog-to-digital converter is responsible for amplifying, converting and filtering the analog input data, and outputting the digital signal to the digital signal processor. The digital-analog converter is responsible for converting the data signal and control signal generated by the computer into an analog signal and outputting it to other subsystem. The digital signal processor is responsible for the fast Fourier transform of the original image data, and the programmable logic device implements logic control on the analog-to-digital converter and other devices in the interface circuit, including register parameter setting and interrupt management.

The working process of the present invention is briefly described as follows:

First, the operator controls the moving bed to move the inspected pipeline to the imaging area, and puts the robot at the beginning of the pipeline. Then, the imaging subsystem images and displays the first section of pipeline, establishes a unified coordinate system required for magnetic positioning and magnetic guidance, and determines the initial coordinates of the robot. The operator uses the computer to make the radio frequency transmitter send out the start signal of the micro motor, which is received by the radio frequency receiver in the robot body, so that the robot enters the standby state. During the movement of the robot, the operator continuously adjusts the moving direction and speed of the robot through the external guidance system, and controls the robot to move in the direction in which the pipeline extends. When the robot needs to move backward, the micro-motor in the robot body is reversed by means of radio frequency signal control to drive the robot to move backward. Finally, when the robot completes the given search task, it needs to control the robot to exit the pipeline in the reverse direction. Similar to the forward movement, the operator moves in the reverse direction and exits the pipeline by controlling the external guidance system of the body.

The present invention adopts a hybrid drive mode of active screw propulsion combined with guided magnetic field attitude control, which solves the contradiction between the miniaturization of the robot volume and the mobility flexibility to a certain extent, and is expected to play an important role in the internal diagnosis and treatment of the human body. In addition, the invention can also be applied to the detection of non-magnetic small pipelines of industrial equipment. The invention realizes non-invasive diagnosis and treatment or detection by combining robot technology, magnetic positioning and guidance technology, tomographic imaging technology, data processing technology and automatic control technology.

In addition, in the hybrid driving mode, the present invention adopts a giant magnetoresistance (GMR) sensor to detect the magnetic field of the permanent magnet block in the micro-robot, which is simpler and more accurate than other existing magnetic positioning methods.

Description of drawings

Figure 1 is a schematic diagram of the internal structure of the micro-robot; in the figure: 1 micro-robot, 2 pipelines, 3 medium in the pipeline, 1a body, 1b permanent magnet block, 1c casing, 1d radio frequency receiver, 1e micro-battery, 1f Micro motor, 1g worm, 1h tail rotating mechanism, 1i tail.

Fig. 2 is a structural block diagram of the in vitro guidance system of the present invention; in the figure: 4 magnetic guidance subsystems, 5 magnetic positioning subsystems, 6 imaging subsystems, and 7 computer control subsystems.

Figure 3 is a schematic diagram of the magnetic guidance subsystem; in the figure: 4a Helmholtz coils in the x direction, 4b Helmholtz coils in the y direction, 4c Helmholtz coils in the z direction, 4d magnetic guidance power supply device, 8 subjects, 9 mobile beds.

Figure 4 is a schematic diagram of the magnetic positioning subsystem; in the figure, 5a is a giant magnetoresistance, 5b is a magnetic positioning power supply device, and 5c is a wire.

Figure 5 is a schematic diagram of the imaging subsystem; in the figure, 6a detector circular array, 6b circular scanning track, 6c X-ray emitter, 6d imaging power supply device.

Fig. 6 is a flow chart of the magnetic positioning inversion algorithm;

Figure 7 is a flow chart of the magneto-steering algorithm.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The internal structure of the micro-robot 1 is shown in Figure 1. Its front end is smooth, and its outer wall has no protrusions or grooves. There is a spiral groove on the outer peripheral surface of the permanent magnet block 1b, which is airtightly matched with the spiral groove at the inner front end of the fuselage 1a. The tail rotating mechanism 1h is fixedly connected with the tail 1i through a rotating rod protruding from the inside of the fuselage. The tail rotating mechanism 1h is composed of a worm 1g, a worm gear, a cam, a rotating rod, a bottom plate, a hinge, a permanent magnet and an electromagnetic coil. The worm 1g is installed on the main shaft of the micromotor 1f. The worm wheel and the cam are coaxially arranged, and the rotating shaft of the worm wheel is installed on the bottom plate. , the bottom plate is pasted on the fuselage, the rotating rod is installed on the hinge, the hinge is fixed on the housing of the micro motor, one end of the rotating rod is fixedly connected with the tail, the other end rests on the cam, and the permanent magnet is fixed on the rotating rod , the electromagnetic coil is located outside the permanent magnet. Tail 1i is made of smooth, flexible biomedical material. The radio frequency receiver 1d is installed on the inner peripheral surface of the rear end of the fuselage 1a. The micro motor 1f and the radio frequency receiver 1d are powered by a micro battery 1e installed in the body 1a, and the battery 1e is installed on the inner peripheral surface of the rear end of the body 1a, and its position is symmetrical with the radio frequency receiver 1d.

The axial movement rate of the micro-robot 1 is controlled by a radio frequency transmitter and a radio frequency receiver 1d. The radio frequency transmitter is part of the computer control subsystem 7 and is integrated on the interface circuit. The radio frequency receiver 1d controls the working state of the micromotor 1f, including its rotational speed and the polarity of the power supply. The micromotor 1f is connected with the tail rotation mechanism 1h through the worm 1g, and drives the microrobot 1 to move forward or backward in the medium 3 in the pipeline. Move backwards.

The permanent magnet block 1b is made of high-performance rare earth permanent magnet materials, such as NdFeB permanent magnet materials. The magnetic positioning subsystem 5 measures the position of the micro robot 1 in the pipeline 2 in real time by sensing the magnetic field excited by the permanent magnet block 1b. The magnetic guiding subsystem 4 can excite a guiding magnetic field along the required direction in the area where the permanent magnet block 1b is located, and the permanent magnetic block 1b is forced to be oriented along the guiding magnetic field by the action of the guiding magnetic field, so that the micro robot 1 moves along the desired path .

As shown in FIG. 2 , the extracorporeal guidance system of the present invention is composed of a magnetic guidance subsystem 4 , a magnetic positioning subsystem 5 , an imaging subsystem 6 and a computer control subsystem 7 .

The computer control subsystem 7 is composed of a computer and an interface circuit, and is used for calculating, coordinating and controlling the work of the micro-robot 1, the magnetic guidance subsystem 4, the magnetic positioning subsystem 5 and the imaging subsystem 6. The signal receiving, processing and sending center also provides the operator with a human-computer interaction interface. In addition to the computer control subsystem 7 , there is also a logical relationship between the magnetic guidance subsystem 4 , the magnetic positioning subsystem 5 , and the imaging subsystem 6 and the micro robot 1 .

The logical relationship shown in Figure 2 includes: the imaging subsystem 6 scans several tomographic images of the area to be imaged, and the obtained original image data is sent to the computer control subsystem 7 for image reconstruction and display; The permanent magnet block 1b is positioned by the magnetic field, and the obtained signal containing position information is sent to the computer control subsystem 7 to reconstruct the position by the magnetic positioning inversion algorithm; the computer control subsystem 7 generates the control signal of the guiding magnetic field and transmits it to the magnetic director System 4 is used to guide and control the micro-robot 1 ; the computer control subsystem 7 sends radio frequency control signals to the micro-robot 1 .

In the magnetic guidance subsystem 4 shown in Figure 3, including three groups of Helmholtz coils 4a, 4b and 4c, when designing the coil geometric parameters, it is considered that the subject 8 is sent into the magnetic guidance subsystem by the moving bed 9 4 o'clock does not make it feel oppressive, three groups of Helmholtz circular coils 4a, 4b and 4c have the same diameter, each group of coils is orthogonal to each other, and is composed of two mirror-image symmetrical coils with a distance of 0.6 meters. The magneto-steering power supply device 4d is used to supply adjustable DC current to the coils 4a, 4b and 4c under the control of the computer control subsystem 7 .

In the magnetic positioning subsystem 5 shown in Figure 4, 8 giant magnetoresistors 5a are used to distribute on the 8 vertices of a cuboid covering the outside of the tested pipeline 2 to measure the permanent magnet in the micro robot 1. Spatial distribution of magnetic field of magnetic block 1b. According to the measured results, the position of the micro robot 1 is obtained through an inversion algorithm. The magnetic positioning subsystem power supply device 5b is responsible for providing a constant DC voltage to the giant magnetoresistance 5a, and the wire 5c is used to connect the giant magnetoresistance 5a and the power supply device 5b into a series-parallel circuit, that is, the giant magnetoresistance 5a is divided into two groups, each group The series mode is adopted, and the parallel mode is adopted between the groups.

As shown in the imaging subsystem 6 in FIG. 5 , the X-ray emitter 6 c performs several circular scans on a series of slices of the pipeline 2 . In each scan, each step of the X-ray emitter 6c on the circular scanning track 6b corresponds to a detector in the detector circular array 6a, and a raw image data is obtained. The detector circular array 6a includes several detectors. When the X-ray emitter 6c completes a circular scan, the scanning data of the corresponding slice is sent to the computer control subsystem 7 for image reconstruction to obtain a slice image. The imaging is obtained by synthesizing several tomographic images. The imaging power supply device 6d is responsible for supplying power to the X-ray emitter 6c and the detector circular array 6a.

The moving bed 9 is a non-magnetic bed. According to the needs of the tomographic imaging subsystem 5 and the magnetic guidance subsystem 2, and considering the moving characteristics of the micro robot 1 in the pipeline 2, its movement form is mainly axial translation, combined with It can be slightly displaced in a plane perpendicular to the axis direction of the subject 8, that is, it has three degrees of freedom, so as to send the region of interest to the effective guidance magnetic field region or imaging region.

The flow chart of the magnetic positioning inversion algorithm shown in Figure 6 first determines the unified coordinate system, and provides the spatial coordinates of each giant magnetoresistance 5a in the coordinate system; according to the geometric shape of the pipeline 2 provided by the imaging subsystem 6, select the pipeline The geometric central axis of road 2 is used as the reference trajectory of robot 1; for a given permanent magnet block 1b, the magnetic induction intensity value of each giant magnetoresistance 5a is calculated when it is located at each point on the reference trajectory by formula (1) , and predict the measured value of each giant magnetoresistance 5a, and establish a position-magnetic field correspondence data table; then, with the cooperation of the external control system of robot 1, make robot 1 move as far as possible along the reference moving track in pipeline 2, and Continuously record the measurement value of each giant magnetoresistance 5a during the moving process; finally, perform curve fitting based on each measurement value combined with the position-magnetic field corresponding data table, and obtain the approximate position corresponding to each moment of the robot 1 .

As shown in the flow chart of the magneto-steering algorithm in Fig. 7, firstly, a reference moving trajectory of the robot 1 is established according to the extended image of the pipeline 2 generated by the imaging subsystem 6, and the geometric central axis of the pipeline 2 is selected as the reference trajectory. Within the effective time of the current image, a series of discontinuous robot position coordinates measured by the magnetic positioning subsystem 5 are connected to obtain a polyline path. The principle of judging the direction of the guiding magnetic field is as follows: when the size of _the robot 1 is much smaller than the length of the pipeline, the robot 1 can be regarded as a mass point, assuming that the robot 1 is located at p ₀ (x ₀ , y ₀ , z ₀ ), without exceeding the position resolution of the magnetic positioning subsystem, after the time period Δt, Δt→0, robot 1 moves to point p ₁ (x ₁ , y ₁ , z ₁ ); find a point on the reference trajectory p′ ₁ , this point is the orthogonal projection of point p ₁ on the reference moving trajectory, and then calculate the directional derivative of the reference moving trajectory in the tangential direction of point p′ ₁ , and the directional derivative from point p ₀ to point p ₁ ; Calculate the difference between the above-mentioned two direction derivatives, and this difference is the correction value of the steering magnetic field direction. Finally, the direction correction value is converted into the guidance magnetic field control parameter corresponding to point _p1 , and is transmitted by the interface circuit to the power supply device 4d of the magnetic guidance subsystem 4, and finally the robot 1 is moved along the reference movement trajectory as much as possible.

Concrete workflow of the present invention is:

1. First, turn on the computer control subsystem 7, and turn on the interface circuit connected with the micro robot 1, the magnetic guidance subsystem 4, the magnetic positioning subsystem 5 and the imaging subsystem 6.

2. Turn on the imaging subsystem 6, and with the cooperation of the moving bed 9, adjust the relative position between the area to be imaged and the X-ray scanning plane, and adjust the corresponding slice, that is, the beginning of the pipeline 2, to the imaging field of view.

3. Turn on the magnetic positioning subsystem 5, and apply a fixed voltage to the series-parallel circuit of the giant magnetoresistance 5a. Place the micro-robot 1 at the beginning of the pipeline 2, and the computer control subsystem 7 sends a radio-frequency micro-motor control signal to the radio-frequency receiver 1d inside the micro-robot 1, and under the control of the radio-frequency receiver 1d, the micro-motor 1f enters a standby state. Next, the magnetic positioning subsystem 5 measures the initial position of the micro robot 1, and sends the data to the computer control subsystem 7 for processing.

Using the magnetic positioning algorithm, the computer control subsystem 7 calculates the initial position of the permanent magnet block 1 b, that is, the initial position of the micro robot 1 . It should be noted that the work of the imaging subsystem 6 on the imaging of the pipeline 2 and the microrobot 1 is carried out periodically, and the relative position between the microrobot 1 and the pipeline 2 is obtained by aligning the magnetic positioning subsystem 5 with the microrobot. 1 The position measured in real time is combined with each frame of image.

叠加后得到的总磁感应强度的方向即为期望的微型机器人1移动方向。4. Combined with the relative position of the pipeline 2 and the micro-robot 1 obtained in the third step, the operator determines the desired movement direction of the micro-robot 1 according to the detection purpose to be realized by the micro-robot 1 . And according to the desired direction, using the magnetic guidance algorithm, the computer control subsystem 7 calculates a group of magnetic induction intensities about the desired direction,

The total magnetic induction intensity obtained after superposition The direction of is the desired moving direction of the micro-robot 1 .

在线圈中通以直流电流会在其周围空间中激发出恒定的磁场。本发明中，利用电源装置4d控制4a、4b、4c三组线圈中直流电流的大小与方向，在磁导向子系统4的中心区域得到所需均匀导向磁场

5. Turn on the magnetic guidance subsystem 4. Through the interface circuit, the computer control subsystem 5 transmits the steering magnetic field control parameters obtained in the fourth step to the power supply device 4d of the magnetic steering subsystem 4, and the power supply device 4d transforms the steering magnetic field control parameters into three sets of Helmholtz coils Variation of current intensity in 4a, 4b and 4c. According to the Ampere loop theorem,

Passing a direct current through the coil excites a constant magnetic field in the space around it. In the present invention, the magnitude and direction of the direct current in the three groups of coils 4a, 4b, and 4c are controlled by the power supply device 4d, and the required uniform guiding magnetic field is obtained in the central area of the magnetic guiding subsystem 4

作用下，微型机器人1中的永磁磁块1b将产生磁转矩，迫使永磁磁块1b沿导向磁场方向取向。同时，计算机控制子系统7通过射频收发器启动微电动机1f，由蜗杆1g带动尾部旋转机构1h与尾部1i，使微型机器人1沿指定方向前进。6. Guide the magnetic field externally

Under the action, the permanent magnet block 1b in the micro robot 1 will generate a magnetic torque, forcing the permanent magnet block 1b to be oriented along the direction of the guiding magnetic field. At the same time, the computer control subsystem 7 activates the micromotor 1f through the radio frequency transceiver, and the worm 1g drives the tail rotating mechanism 1h and the tail 1i to make the microrobot 1 move forward in a specified direction.

7. Continuous control of the moving direction and speed of the micro robot 1 during the moving process. Due to the uncertainty of the internal size and extension direction of the pipeline 2, the moving direction and speed of the micro-robot 1 must be adjusted at any time, which requires the operator to constantly obtain the relative position of the pipeline 2 and the micro-robot 1 through the external guidance system of the micro-robot 1 information, and finally move the micro robot 1 to the designated position through the in vitro guidance control system.

8. When the micro-robot 1 completes the given search task, or needs to move backward due to encountering obstacles, etc., similar to when moving forward, the computer control subsystem 7 transmits a radio frequency drive signal to the micro-robot 1 through a radio frequency transmitter, The micro-motor 1f drives the tail part 1i to reversely rotate, so that the micro-robot 1 can move backward. And, the same as advancing, the retreating process also needs to be carried out under the control of the in vitro guidance control system.

Claims (6)

1. A micro-robot, the inside of the fuselage [1a] is hollowed out, and a radio frequency receiver [1d], a micro-battery [1e] and a micro-motor [1f] are arranged. There is a spiral groove for arranging the permanent magnet block [1b]. The outer peripheral surface of the permanent magnet block [1b] has a spiral groove, which is tightly matched with the ring spiral groove at the front end of the fuselage [1a]; the bottom of the fuselage [1a] is opened There is an axial through hole; the tail rotating mechanism [1h] is fixedly connected with the tail [1i] through the rotating rod protruding from the through hole of the fuselage [1a], and the rotating rod and the fuselage [1a] are sealed with a highly elastic sealing film The front end of the micro-robot [1] is smooth, and there are no protrusions or grooves on the surface of the outer wall; the radio frequency receiver [1d] is installed on the inner peripheral surface of the rear end of the fuselage [1a], and the micro-motor [1f] and the radio frequency receiver [1d] are composed of The micro battery [1e] supplies power, and the battery [1e] is installed on the inner peripheral surface of the rear end of the fuselage [1a], and its position is symmetrical to that of the radio frequency receiver [1d]; [1f] The main shaft is connected to drive the micro robot [1] to move forward or backward; the tail rotation mechanism [1h] is composed of a worm [1g], a worm wheel, a cam, a rotating rod, a bottom plate, a hinge, a permanent magnet and an electromagnetic coil , the worm [1g] is installed on the main shaft of the micro-motor [1f], the worm gear and the cam are coaxially arranged, the rotating shaft of the worm gear is installed on the base plate, the base plate is pasted on the fuselage [1a], and the rotating rod is installed on the hinge, The hinge is fixed on the housing of the micro motor [1f], one end of the rotating rod is fixedly connected to the tail [1i], the other end of the rotating rod is connected to the cam, the permanent magnet is fixed on the rotating rod, and the electromagnetic coil is located on the permanent magnet. outside. 2. An in vitro guidance system for a microrobot as claimed in claim 1, characterized in that it comprises a magnetic guidance subsystem [4], a magnetic positioning subsystem [5], an imaging subsystem [6] and a computer control subsystem [ 7]; the computer control subsystem [7] is connected with the micro robot [1], the magnetic guide subsystem [4], the magnetic positioning subsystem [5] and the imaging subsystem [6] respectively; the imaging subsystem [6] is to be detected The area is scanned continuously tomographically, and the original image data obtained are sent to the computer control subsystem [7] for image reconstruction and display, and the magnetic positioning subsystem [5] carries out the Magnetic positioning, the original position information obtained is sent to the computer control subsystem [7] for position reconstruction, the computer control subsystem [7] generates guidance control information and transmits it to the magnetic guidance subsystem [4], the magnetic guidance subsystem [4] The micro-robot [1] is guided and controlled, and the computer control subsystem [7] sends a radio frequency control signal to the micro-robot [1]. 3. The in vitro guidance system for microrobots according to claim 2, characterized in that in the magnetic guidance subsystem [4], the three sets of Helmholtz coils [4a, 4b, 4c] are all axisymmetric structures, The diameters are equal, and the pairs are orthogonal; each group of coils is composed of two pairs of circular coils parallel to each other. 4. The in vitro guidance system for microrobots according to claim 2, characterized in that in the magnetic positioning subsystem [5], 8 giant magnetoresistances [5a] are used, arranged in two layers in the pipeline [2] The exterior of the tester is divided into two layers parallel to each other in the direction of the subject's axis to detect the distribution of the magnetic field of the permanent magnet in the micro-robot [1] in real time, and compare the detection results with the known magnetic field distribution data. In comparison, the position information of the micro-robot [1] is obtained through the magnetic positioning inversion algorithm. 5. According to claim 3, the in vitro guidance system for micro-robots is characterized in that the computer control subsystem [7] uses the magnetic positioning inversion algorithm to perform position reconstruction as follows: first determine the unified coordinate system, and give each giant The spatial coordinates of the magnetic resistance [5a] in the coordinate system; according to the geometric shape of the pipeline [2] provided by the imaging subsystem [6], the geometric center axis of the pipeline [2] is selected as the reference movement of the robot [1] trajectory; for a given permanent magnet block [1b], calculate the magnetic induction intensity value of each giant magnetoresistance [5a] when it is located at each point on the reference moving trajectory, and predict the measurement of each giant magnetoresistance [5a] value, establish a position-magnetic field correspondence data table; then, with the cooperation of the external control system of the robot [1], make the robot [1] move along the reference movement track as much as possible in the pipeline [2], and during the movement process Continuously record the measured value of each giant magnetoresistance [5a]; finally, perform curve fitting on each measured value combined with the position-magnetic field corresponding data table to obtain the approximate position corresponding to each moment of the robot [1]. 6. The in vitro guidance system for micro-robots according to claim 2, characterized in that the computer control subsystem [7] controls the moving direction of the robot through the magnetic guidance algorithm as follows: First, according to the imaging subsystem [6] The generated extended image of the pipeline [2] establishes a reference trajectory of the robot [1], and selects the geometric center axis of the pipeline [2] as the reference trajectory; within the effective time of the current image, the magnetic positioning subsystem [5] is measured A series of discontinuous robot position coordinates are connected to obtain a polyline path; when the size of the robot [1] is much smaller than the length of the pipeline, the robot [1] can be regarded as a particle, assuming that at t=t ₀ , the robot [ 1] located at p ₀ (x ₀ , y ₀ , z ₀ ), without exceeding the position resolution of the magnetic positioning subsystem, the robot [1] moves to p ₁ (x ₁ , y ₁ , z ₁ ) point; find a point p′ ₁ on the reference moving track, which is the orthogonal projection of point p ₁ on the reference moving track, and calculate the direction of the reference moving track in the tangential direction of point p′ ₁ Derivative, and the directional derivative from point p ₀ to point p ₁ ; then calculate the difference between the above two direction derivatives, this difference is the correction value of the direction of the steering magnetic field; finally convert the direction correction value to correspond to p ₁ Point guidance magnetic field control parameters are transmitted by the interface circuit to the power supply unit [4d] of the magnetic guidance subsystem [4], so that the robot [1] can move along the reference trajectory as much as possible.

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