KR101248818B1 - Surgical robot and system for minimally invasive surgery including fiber bragg grating force sensor and method for measuring force using the system - Google Patents

Abstract

The present invention relates to a surgical robot for minimally invasive surgery having a fiber Bragg grating force sensor, a system, and a force measuring method using the system. More specifically, the load cell for measuring the force and the moment applied; At least one joint part connected to the load cell and having a degree of freedom; A flexure for measuring an end force applied to the end of the joint part by the force and the moment measured by the load cell; A plurality of pillars provided between the load cell and the flexure; A measurement FBG provided in the optical fiber and installed on each of the pillars to reflect only a specific wavelength of incident light; A broadband light source for injecting broadband light into the optical fiber; A wavelength measuring device for measuring an amount of change in reflected wavelength reflected by the measurement FBG; A photodiode measuring the amount of light incident on the wavelength measuring device; And analysis means for obtaining the force and moment measured in the load cell from the reflected wavelength change amount measured by the wavelength measuring device, and analyzing the end force applied by the flexor to the end of the joint from the force and the moment. It relates to a minimal surgical surgery system having an optical fiber Bragg grating force sensor.

Description

Surgical robot and system for minimally invasive surgery including fiber bragg grating force sensor and method for measuring force using the system

The present invention relates to a surgical robot for minimally invasive surgery having a fiber Bragg grating force sensor, a system, and a force measuring method using the system. More specifically, the present invention relates to a surgical system for minimally invasive surgery using an optical fiber Bragg grating force sensor to measure the force applied to the joint end of the surgical robot in real time.

Minimally invasive surgery has grown significantly since 1980 based on the patient's great recovery time and beauty. However, more restrictions were placed on the physicians, which caused side effects such as prolonged operation time and decreased surgical completion. In order to improve this, a minimally invasive robot was introduced.

The Da Vinci system, the most invasive minimally invasive robot currently used, solves the problem of lack of freedom caused by minimally invasive surgery and two-dimensional imaging due to the use of endoscope. However, there is a problem that the absence of tactile information has become more severe. Tactile information, which was weak in minimally invasive surgery, disappeared completely with robotic surgery.

Existing researchers anticipate a much safer and more complete operation if force reflexes are combined with laparotomy in robotic surgery. Several attempts have been made to add force sensors to minimally invasive robots to achieve this, but the lack of sensor installation space, weakness in harsh surgical conditions, and so on make it difficult to realize them. There is no surgical robot capable of force reflection.

One important technology that can help solve this problem is the fiber optic sensor technology. The optical fiber sensor is thin in hair thickness, and has a characteristic that it is not easily broken when coated, and has a flexible characteristic, so that it is easy to access the end-effector of the surgical tool. In addition, since an optical signal instead of an electrical signal is used as an input / output signal, it is not affected by electromagnetic waves and thus does not cause interference with other sensors, and can be used even in an MRI environment.

In addition, the optical fiber sensor can withstand high temperatures and does not corrode even in a humid environment, so that the conventional general disinfection method can be applied as it is when disinfecting surgical instruments. Much research has been conducted on the force reflection of surgical robots. However, existing systems are made of electric system considering reliability and simplicity. However, electrical systems require a large number of wires, and electromagnetic shielding is inevitable. In addition, the surgical robot must consider disinfection before and after use. Currently, steam sterilization is called an autoclave in a typical surgical environment. It instantly concentrates heat, pressure and moisture, destroying germs. Therefore, the force sensor must also not be damaged in this process.

Optical fibers are not affected by all these conditions, making them one of the most suitable materials for use as force sensors in robotic surgical environments. Optical fibers are not affected by electromagnetic interference (EMI), are light in weight, flexible, can withstand high temperatures, and can be used in MRI environments. The thin thickness of the optical fiber is suitable for use in manipulators of thin and long surgical robots. However, since all of the conventional optical fiber sensors emit light from the light source and measure the intensity of the reflected light reflected by the reflector, the intensity of the light source is not constant. If not, or if the ambient light is affected, the result is a disadvantage. However, the use of an optical fiber Bragg grating (FBG) sensor, which is being actively studied recently, can alleviate this inconvenience. Because the FBG sensor measures the wavelength, not the light intensity, it is not affected by light sources or ambient light.

Therefore, a minimally invasive surgical robot with an optical fiber Bragg grating force sensor was required.

The present invention has been made to solve the above problems, and relates to the principle and application method of the FBG optical fiber force sensor for applying to the manipulator for minimally invasive surgery, the tactile sensation that emerged as a problem in conventional robotic minimally invasive surgery Has a purpose to solve the member.

The FBG optical fiber force sensor can be applied to both long and thin manipulators, which can be extended to non-invasive manipulators such as NOTES surgery.

Therefore, according to one embodiment of the present invention as described, by applying the FBG optical fiber force sensor to the surgical robot, the force reflection can be measured in real time, and the safety of the force can be adjusted, which is a burden on the doctor. It is possible to provide a surgical robot and a system for minimally invasive surgery with an optical fiber Bragg grating force sensor that can significantly reduce the operation time. In addition, by using only the appropriate force to manipulate the organ, it is possible to minimize the damage to the organ, thereby providing a surgical robot and system for minimally invasive surgery equipped with an optical fiber Bragg grating force sensor that can help improve the surgical results. .

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

An object of the present invention is a surgical robot for minimally invasive surgery, the load cell for measuring the applied force and moment; At least one joint part connected to the load cell and having a degree of freedom; A flexure for measuring an end force applied to the end of the joint by a force and a moment measured in the load cell; A plurality of pillars provided between the load cell and the flexure; Measurement FBG provided in the optical fiber and installed in each of the pillars to reflect only a specific wavelength of incident light; A broadband light source for injecting broadband light into the optical fiber; And a wavelength measuring device for measuring the reflected wavelength and the reflected wavelength variation of the light reflected by the measurement FBG, and obtaining the force and moment measured in the load cell from the reflected wavelength variation measured in the wavelength measuring instrument. Minimally invasive surgical robot with an optical fiber Bragg grating force sensor, characterized in that to measure the end force applied to the joint end.

It may be characterized in that it further comprises a compensation FBG provided in the pillar for compensating the reflected wavelength according to the temperature.

The joint part includes a first joint connected to the load cell; And a second joint connected to an end of the first joint to perform an independent degree of freedom movement, and the surgical robot may measure an end force applied to the end of the second joint from the amount of change in the reflection wavelength.

It may further comprise a control unit for controlling the rotation angle of each of the first and second joints by controlling the driving means and the driving means for driving the first and second joints.

Still another object of the present invention is a surgical system for minimally invasive surgery, the load cell for measuring the applied force and moment; At least one joint part connected to the load cell and having a degree of freedom; A flexure for measuring an end force applied to the end of the joint by a force and a moment measured in the load cell; A plurality of pillars provided between the load cell and the flexure; Measurement FBG provided in the optical fiber and installed in each of the pillars to reflect only a specific wavelength of incident light; A broadband light source for injecting broadband light into the optical fiber; A wavelength measuring device for measuring an amount of change in reflected wavelength reflected from the measurement FBG; A photodiode measuring the amount of light incident on the wavelength measuring device; And an analysis means for obtaining the force and moment measured in the load cell from the reflected wavelength variation measured in the wavelength measuring device and analyzing the end force applied by the flexure to the end of the joint from the force and moment. A minimally invasive surgical system with a force sensor can be achieved.

It may be characterized in that it further comprises a compensation FBG provided in the pillar for compensating the reflected wavelength according to the temperature.

It may be characterized in that it further comprises an isolator provided on the output side of the broadband light source for preventing the back of the light irradiated from the broadband light source.

It may be characterized in that it further comprises a coupler provided between the broadband light source and the measurement FBG to distribute the light emitted from the broadband light source in a plurality of paths.

The measurement FBG may be attached to a pillar and deformed in synchronization with the deformation of the pillar, thereby measuring the strain of the pillar based on the variation in the reflection wavelength from the variation in the reflection wavelength.

The wavelength measuring device comprises a Fabry-Parrot filter, and the Fabry-Parrot filter includes a piezoelectric actuator for changing the distance between two mirror surfaces and two mirror surfaces, and scans the wavelength band of the reflected wavelength and passes only a specific wavelength. You can do

The joint part includes a first joint connected to the load cell; And a second joint connected to an end of the first joint to perform an independent degree of freedom movement, and the surgical robot may measure an end force applied to the end of the second joint from the amount of change in the reflection wavelength.

The light emitted from the broadband light source is passed to the measurement FBG side, the reflected light reflected from the measurement FBG may be characterized in that it further comprises a circulator for sending to the wavelength measuring device side.

In another category, an object of the present invention is to provide a force measuring method using a surgical system for minimally invasive surgery, the light is emitted from the broadband light source to enter a plurality of optical fibers; Light incident on the optical fiber is incident on the measurement FBG installed on each of the plurality of pillars of the surgical robot to reflect a specific wavelength; Measuring the reflected wavelength of the light reflected by the measurement FBG in a wavelength measuring device in real time; Measuring, by the photodiode, the amount of light passing through the wavelength measuring device; When the analysis means is applied to the end of the joint of the surgical robot based on the reflected wavelength measured in real time by the wavelength measuring device and the amount of light measured by the photodiode, the measurement FBG is also deformed by the deformation of the column. Calculating a force applied by the end of the joint in real time by measuring a change in wavelength and calculating a strain of the pillar from the change in wavelength to measure a force and a moment applied to the load cell provided between the joint and the pillar from the strain; It can be achieved by a force measuring method using a surgical system for minimally invasive surgery with an optical fiber Bragg grating force sensor.

The reflecting of the specific wavelength further includes compensating the reflected wavelength according to the temperature by the compensation FBG provided in the pillar, and before the reflecting of the specific wavelength, the coupler provided between the broadband light source and the measuring FBG may be Dispersing the irradiated light in a plurality of paths may be further characterized.

Therefore, according to one embodiment of the present invention as described, by applying the FBG optical fiber force sensor to the surgical robot, the force reflection can be measured in real time, and the safety of the force can be adjusted, which is a burden on the doctor. It has the advantage that it can significantly reduce the operation time. In addition, by using only the appropriate force to manipulate the organ, it is possible to minimize the damage to the organ, it has an effect that can help to improve the surgical results.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be appreciated by those skilled in the art that various other modifications and variations can be made without departing from the spirit and scope of the invention, All fall within the scope of the appended claims.

1A is a block diagram of a system for minimally invasive surgery with an optical fiber Bragg grating (FBG) force sensor according to an embodiment of the present invention;
1B shows reflected wavelengths (λ _ref1 , λ _ref2 , λ _ref3 , λ _ref4 ) and measured FBG of a compensation FBG 105 measured by a system for minimally invasive surgery with an FBG force sensor according to an embodiment of the present invention. Graph of the amount of reflected wavelengths (λ ₁ , λ ₂ , λ ₃ , λ ₄ ) of (106),
2 is a perspective view of a robot for minimally invasive surgery having an optical fiber Bragg grating (hereinafter referred to as FBG) force sensor according to an embodiment of the present invention;
3 is a sectional view taken along the line AA in Fig. 2,
4 is a simplified operation of FIG. 2 to illustrate how the load cell 203 according to an embodiment of the present invention can measure the force applied to the end of the surgical tool (the end of the first joint 201). Perspective view of robot,
5 shows a graph of an input voltage and a wavelength applied to a piezoelectric driver and a graph of an output voltage and a wavelength of a photodiode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is connected to another part, this includes not only the case where it is directly connected, but also the case where it is indirectly connected with another element in between. In addition, the inclusion of an element does not exclude other elements, but may include other elements, unless specifically stated otherwise.

<Of the present invention Example  According to optical fiber Bragg  grid Force sensor  Configuration of Surgical Robot and System for Minimally Invasive Surgery>

Hereinafter, the configuration of the minimally invasive robot 1 and the system 100 including the optical fiber Bragg grating (hereinafter referred to as FBG) force sensor according to an embodiment of the present invention will be described. First, FIG. 1A illustrates a schematic diagram of a system for minimally invasive surgery having an optical fiber Bragg grating (FBG) force sensor according to an embodiment of the present invention. 2 shows a perspective view of a robot for minimally invasive surgery 1 having an optical fiber Bragg grating (FBG) force sensor according to an embodiment of the present invention.

Although the robot 1 and the system 100 for minimally invasive surgery according to the present invention may have various configurations, the temperature of the four measuring FBG 106 and the measuring FBG 106 attached to each of the four pillars is here. The minimally invasive robot 1 and the system 100 equipped with four compensation FBGs for compensating for the deformation due to the error and the time-dependent error of the Fabry-Parrot filter will be described.

In addition, the basic principle and configuration are similar in the case of three pillars or one or two compensation FBGs 105. As shown in FIG. 2, it can be seen that four measurement FBGs 106 are attached to each of the four pillars connected to the flexure. The remaining four compensation FBGs 105 will be located in a similar position to each measurement FBG 106. They are freely suspended inside the cylinder of the surgical robot 1 so that no force is applied. At this time, these eight FBGs (measurement FBG 106 and compensation FBG 105) may be located in one strand of optical fiber 10 or may be located in several strands of optical fiber 10. However, it is more preferable to use the same number of optical fibers 10 as the number of pillars as a limit for the radius of curvature of the optical fibers 10.

As shown in FIG. 1, the minimally invasive surgical system 100 having an FBG force sensor according to an embodiment of the present invention includes a broadband light source 101 for irradiating light onto an optical fiber 10. It can be seen that the circulator 103 passes through the isolator 102 which prevents the retrograde of light emitted from the broadband light source 101. Then, the light passing through the circulator 103 enters the 1x4 coupler (Coupler, 104).

Here, the role of the circulator 103 is to send light to the other side (fabric-parrot filter side) rather than the broadband light source 101 side when the light exiting the output is reflected back from the measurement FBG 106. do. This can also be implemented using a 2x2 coupler, but it is more preferable to use the circulator 103 because the amount of light is reduced.

Light passing through the circulator 103 is directed to the optical fiber bundle 10 for wavelength measurement. In this case, since the four optical fibers 10 are described, the light is divided into four using the 1 × 4 coupler 104. The light divided into four through the coupler 104 enters one optical fiber 10. One strand of optical fiber 10 is inscribed with one measuring FBG 106 and one compensating FBG 105, respectively.

Light reflects a specific wavelength at the compensation FBG 105 and the measurement FBG 106, respectively, and transmits other wavelengths. And, as will be described in detail later, for measuring the strain (strain) of the pillar 205 provided in the surgical robot 1, it is possible to use either reflected or transmitted wavelengths, but using the reflected device Is preferred.

And, as shown in Figure 1, it can be seen that enters the wavelength measuring device again through the circulator 103. There are many wavelength measurement devices, but the Optical Spectrum Analyzer (OSA) and Tunable Fabry-Perot Filter (TFPF) are typical. In an embodiment of the present invention, as shown in FIG. 1A, a measurement is more difficult than a wavelength analyzer capable of obtaining an absolute wavelength value, but a fast response can be expected, and thus, a variable Fabry-Parrot filter which is frequently used for real-time measurement ( The measurement method using 107) will be described.

The variable Fabry-Parrot filter 107 is provided with two mirror surfaces, and applies a voltage to a piezo-actuator to adjust a distance between the two mirror surfaces, thereby passing only a specific wavelength according to the voltage. Device. Therefore, by applying the voltage of the triangular wave to the piezoelectric actuator, it may serve to scan the wavelength of the optical signal. In addition, the fabric may further include a Fabry-Parrot filter controller 110 connected to and controlling the Fabry-Parrot filter 107.

As shown in FIG. 1, the light passing through the Fabry-Parrot filter 107 may be measured by the intensity of the photodiode 108. The scanned values are connected to analysis means 109 provided by a computer or the like for analysis. 1B shows reflected wavelengths (λ _ref1 , λ _ref2 , λ _ref3 , λ _ref4 ) of the compensated FBG 105 measured by the minimally invasive surgical system 100 having an FBG force sensor according to an embodiment of the present invention. And a graph of the light amount of the reflected wavelengths λ ₁ , λ ₂ , λ ₃ , and λ ₄ of the measured FBG 106.

As shown in FIG. 1B, the position of the reflection wavelength of the compensation FBG 105 and the position of the reflection wavelength of the measurement FBG 106 for setting a reference and performing temperature compensation may vary depending on the design, but it is accurate to mix them evenly. Is advantageous to ensure. Of the peak values of the reflected wavelength signal, if the four values of the compensation FBG 105 are compensated for, the peak values obtained from the four measurement FBG 106 can be used to change the strain.

<Method for Measuring Surgical Robot Tip Force>

Hereinafter, a method of measuring the end force of the surgical robot 1 for minimally invasive surgery having an optical fiber Bragg grating force sensor according to an embodiment of the present invention. Surgical robot 1 according to an embodiment of the present invention is to measure the force of the three axes to stand four columns in the axial direction as shown in FIG. These four columns are provided between the flexure 204 and the load cell 203.

However, in another embodiment, the same effect can be obtained by using three pillars having an angle of 120 degrees in the axial direction. The four columns are arranged so that the section of the surgical instrument is divided into four quarters around the circle. 3 is a cross-sectional view taken along the line A-A of FIG. That is, the two pillars have a shape facing each other as shown in FIG. In addition, the surgical robot 1 according to an embodiment of the present invention includes a flexure 204 or a transducer for converting the measured physical quantity into a desired physical quantity.

As described above, the FBG sensor is divided into a measurement FBG (Active FBG) 106 where actual measurement is performed and a compensation FBG (reference FBG) 105 for temperature compensation, and the measurement FBG 106 is shown in FIG. It is fixed with epoxy along the axial direction on the four pillars to have the same strain as the pillars 205.

At this time, in order to prevent slip between the pillar 205 and the optical fiber 10, it is preferable to remove the acrylate coating from the measurement FBG 106. The compensation FBG 105 is also used to compensate for the deformation caused by the temperature of the measurement FBG 106 and to establish a reference for measuring the amount of change in the wavelength of the measurement FBG 106. The compensation FBG 105 is not to be deformed so that the surgical robot 1 is positioned with an acrylate coating away from the joint, if the joint is present.

Since the optical fiber 10 has a very thin diameter, even with an acrylate coating, the optical fiber 10 can go out without disturbing the driving wire to the order of several hundred microns. Since the measurement FBG 106 and the compensation FBG 105 must be located in the abdominal cavity together for temperature compensation, the compensation FBG 105 should be located very close to the measurement FBG 106.

As shown in FIG. 2, the surgical robot 1 according to an embodiment of the present invention has two joints (first joint and second joint) between the flexure 204 and the end of the surgical robot 1. It can be seen that the application of the optical fiber sensor. The measuring FBG 106 is glued to the pillar 205 connected to the flexure 204 and the compensating FBG 105 is located close to the measuring FBG 106 but not to be affected by the deformation of the pillar 205. It is not adhered to the pillar 205. The position of the measurement FBG 106 may be somewhat free if it is located in the abdominal cavity with the measurement FBG 106, but not the flexure 204.

4 is a simplified operation of FIG. 2 to illustrate how the load cell 203 according to an embodiment of the present invention can measure the force applied to the end of the surgical tool (the end of the first joint 201). It is a perspective view of the robot 1. In addition, the present invention can be applied even if there are three or more joints at the end of the surgical tool. This article only describes the case of two joints.

If there are more joints, add angle variables one by one. If there are fewer joints, calculate the given angle variable as 0 degrees. As shown in FIG. 4, the distance between the second joint 202 and the second joint 202 in the flexure 204 to which the FBG sensors (compensating FBG 105 and measuring FBG 106) are attached is d _s . ) Is the rotation angle of the load cell 203 based on the longitudinal direction of θ ₁ , and the distance from the second joint 202 to the first joint 201 (ie, the length of the second joint 202 is d ₁ , The angle of rotation of the first joint 201 based on the longitudinal direction of the second joint 202 is θ ₂ , and the position from the first joint 201 to the place where the force of the end of the surgical robot 1 is applied (ie, It can be seen that the length of one joint) is represented by d ₂ .

In addition, the end of the surgical robot (1) (end of the first joint 201) is pointed, assuming that the external end takes all the external force, three-dimensional force (F _x , F _y , F _z ) can be expressed only. That is, only the force in each axial direction at the end of the surgical robot 1, there is no moment. In addition, assuming that there is no deformation due to the elasticity of the wire in each joint, the force applied to the end of the surgical robot 1 using the previously defined θ ₁ , θ ₂ , d ₁ , d ₂ , and d _s (F _x , F _y) , F _z ) and the force between the center of the load cell (F _X , F _Y , F _Z ) and moment (M _X , M _Y , M _Z ) can be defined by the following equation: have.

In Equation 1, d ₁ , d ₂ , and d ₃ are all determined values, and θ ₁ and θ ₂ are values that are determined at that time, and are usually values obtained by reading encoder values of a driving motor. Thus, the intermediate 6 x 3 matrix is then a matrix of all constants. Therefore, at this time, if three of the six terms (F _X , F _Y , F _Z ) and moments (M _X , M _Y , M _Z ) applied to the center of the load cell 203 of the matrix on the left side are known, the surgical robot (1 You can find the force (F _x , F _y , F _z ) on the end of the joint (first joint). Here, F _x , F _y , and F _z are _calculated using F _Z , M _X , and M _Y, which are relatively easy to measure in the load cell 203. Subtracting the portion of F _Z , M _X , M _Y in the above equation 1 can be represented by the following equation (2).

In addition, F _Z , M _X , and M _{Y that} are applied to the center of the load cell 203 may be measured based on the following principle. When the force of F _Z acts on the load cell 203, the four pillars 205 are compressed by the same length. In addition, when M _X or M _Y acts, the pillars 205 facing each other are subjected to compression and the other to be tensioned. Therefore, by measuring the compression and tension of the four pillars 205 and decomposing it by the following equation (3) it is possible to measure F _Z , M _X , M _Y.

In Equation 3, E is the Young's Modulus of the material of the load cell 203, C is the radius of the load cell 203, A is the width of the cross section of the load cell 203, and I is the area moment of inertia of the cross section. Inertia of an area. Therefore, in Equation 3, since E, A, C, and I are all constant values, the strain (strain, ε ₁ , ε ₂ , ε ₃ , ε ₄ ) of each column 205 is measured as an average of each strain. F _Z can be calculated and M _X and M _Y can be measured by measuring the difference in strain between two opposite columns.

In addition, using the equations (3) and (2), it is possible to finally obtain the forces (F _x , F _y , F _z ) applied to the end of the surgical robot (1). These measured forces F _x , F _y , F _z can be used to prevent any accidents, such as tying the thread or tearing other organs, with an effective force in sewing the affected area.

In addition, measuring the strain ε ₁ , ε ₂ , ε ₃ , ε ₄ of each pillar 205 is the wavelength of the measurement FBG 106 attached to each pillar and the compensation FBG 105 for compensation of various errors. Can be measured. FBG is a technique of making a kind of filter by repeatedly changing the refractive index of the core of the optical fiber 10, the wavelength of reflection is changed depending on the interval of the grating repeatedly carved. Therefore, by attaching it to the pillar 205 and tracking the reflected wavelength, the strains ε ₁ , ε ₂ , ε ₃ , ε ₄ of the pillar 205 can be found. However, since the reflected wavelength is also affected by the temperature, in one embodiment of the present invention, the compensation FBG 105 is placed near the measurement FBG 106 to remove the amount changed by the temperature.

In addition, the reflected wavelength can be determined using various devices. Typically, this can be found using a wavelength analyzer (OSA (Optical Spectrum Analyzer)). In addition, a variable Fabry-Parrot filter 107 having excellent response speed may be used for real-time measurement.

5 shows a graph of an input voltage and a wavelength applied to a piezoelectric driver and a graph of an output voltage and a wavelength of a photodiode. Since the Fabry-Parrot filter 107 cannot measure the absolute value of the wavelength, it is applied in the piezoelectric driver for driving the Fabry-Parrot filter corresponding to the reflected wavelength already measured by the wavelength analyzer (OSA) as shown in FIG. 5. Experimentally measure the voltage, and draw a graph of the voltage-wavelength. However, this method does not measure the change in the reflected wavelength influenced by the temperature, and takes an indirect method of using a voltage corresponding to the wavelength, so that the measurement error is also increased.

Therefore, in one embodiment of the present invention, the relationship between the positions and the reflected wavelengths using the compensation FBG 105 having the known reflected wavelength measured by the wavelength analysis (OSA) as shown in the light quantity graph shown in FIG. By using the first- or second-order fitting to draw a position-wave graph, the reflected wavelengths of the measured FBGs 105 can be measured at a relative position. The advantage of this method is that if the reflected wavelength is changed by temperature, the compensated FBG 105 also moves the reflected wavelength, so the influence of temperature is compensated without any calculation, and the value of the photodiode 108 measured first is intact. By using it, there is an advantage in that an error by an indirect method of reading and using a corresponding voltage value can be eliminated.

In this way, the wavelength change can be obtained by comparing the wavelength of the measured FBG 106 measured in real time with the wavelength of the measured FBG 106 before the force is applied. The wavelength change amount may be calculated by Equation 4 below according to the temperature and the strain rate.

In Equation 4, λ _B is the Bragg reflection wavelength before deformation (before the force is applied), α _f is the thermal expansion coefficient of the optical fiber 10, ξ _f is a heat representing the change of the refractive index of the optical fiber 10 with temperature change The optical coefficient, p _e, is a photoelastic constant.

Since the change amount due to temperature is compensated by the compensation FBG 105, the change amount of the wavelength can be converted into the change amount of the strain. The optical fiber 10, which is commonly used as an FBG, has a central wavelength around 1550 nm, which corresponds to a variation in strain of about 1000 mu ε to a wavelength change of 1 nm. However, when making an actual sensor, it is desirable to carry out the calibration by experimenting with this value in mind and using a known weight. Using the strain change amount thus obtained, it is possible to measure the force (F _X , F _Y , F _Z ) applied to the end of the surgical tool by the above equations (1) to (3).

1: surgical robot
10: optical fiber
100: Surgery system
101: broadband light source
102: Isolator
103: circulator
104: coupler
105: Compensation FBG
106: Measure FBG
107: Fabry-Parrot filter
108: photodiode
109: means of analysis
110: Fabry-Parrot filter controller
201: Joint 1
202: second joint
203: load cell
204: A flexor
205: pillar

Claims (14)

In the minimally invasive surgical robot,
A load cell measuring the applied force and moment;
At least one joint part connected to the load cell and having a degree of freedom;
A flexure for measuring an end force applied to the end of the joint part by the force and the moment measured by the load cell;
A plurality of pillars provided between the load cell and the flexure;
A measurement FBG provided in the optical fiber and installed on each of the pillars to reflect only a specific wavelength of incident light;
A broadband light source for injecting broadband light into the optical fiber; And
A wavelength measuring device for measuring a reflected wavelength of the light reflected by the measurement FBG and an amount of change of the reflected wavelength to obtain the force and the moment measured in the load cell from the reflected wavelength change measured in the wavelength measuring device; Minimally invasive surgical robot with a fiber Bragg grating force sensor, characterized in that for measuring the end force applied to the end of the joint from the moment from the moment.
The method of claim 1,
The surgical robot for minimally invasive surgery with an optical fiber Bragg grating force sensor further comprises a compensation FBG provided on the pillar to compensate for the reflected wavelength according to temperature.
The method of claim 1,
The joint part
A first joint connected to the load cell; And
And a second joint connected to an end of the first joint to perform an independent degree of freedom movement, wherein the surgical robot measures an end force applied to the end of the second joint from the reflected wavelength change amount. Minimally Invasive Surgical Robot with Bragg Lattice Force Sensor.
The method of claim 3, wherein
And a control unit for driving the first and second joints and a control unit controlling the driving means to adjust rotation angles of the first and second joints, respectively. Surgical robot for minimally invasive surgery.
In the minimally invasive surgical system,
A load cell measuring the applied force and moment;
At least one joint part connected to the load cell and having a degree of freedom;
A flexure for measuring an end force applied to the end of the joint part by the force and the moment measured by the load cell;
A plurality of pillars provided between the load cell and the flexure;
A measurement FBG provided in the optical fiber and installed on each of the pillars to reflect only a specific wavelength of incident light;
A broadband light source for injecting broadband light into the optical fiber;
A wavelength measuring device for measuring an amount of change in reflected wavelength reflected by the measurement FBG;
A photodiode measuring the amount of light incident on the wavelength measuring device; And
And an analysis means for obtaining the force and moment measured in the load cell from the reflected wavelength change amount measured by the wavelength measuring device, and analyzing the end force applied by the flexor to the end of the joint from the force and the moment. A surgical system for minimally invasive surgery with an optical fiber Bragg grating force sensor.
6. The method of claim 5,
Minimally invasive surgery system with a fiber Bragg grating force sensor characterized in that it further comprises a compensation FBG provided on the pillar to compensate for the reflected wavelength according to the temperature.
The method according to claim 6,
Minimally invasive surgery system with an optical fiber Bragg grating force sensor, characterized in that it further comprises an isolator provided on the output side of the broadband light source for preventing the retrograde of light irradiated from the broadband light source.
The method according to claim 6,
And a coupler provided between the broadband light source and the measurement FBG to disperse the light emitted from the broadband light source in a plurality of paths.
The method of claim 8,
The measurement FBG is attached to the pillar and deformed in synchronization with the deformation of the pillar, thereby measuring the strain of the pillar based on the variation of the reflected wavelength from the variation of the reflected wavelength. Surgical System for Minimally Invasive Surgery.
The method of claim 9,
The wavelength measuring device is composed of a Fabry-Parrot filter,
The Fabry-Parrot filter includes an optical fiber Bragg grating force sensor, which includes a piezoelectric actuator for changing the distance between the two mirror surfaces and the two mirror surfaces, and scans the wavelength band of the reflected wavelength and passes only a specific wavelength. One minimally invasive surgical system.
The method of claim 10,
The joint part
A first joint connected to the load cell; And
And a second joint connected to the end of the first joint to perform an independent degree of freedom movement,
And the analyzing means measures an end force applied to the end of the second joint from the amount of change in the reflected wavelength. The surgical system for minimally invasive surgery having an optical fiber Bragg grating force sensor.
6. The method of claim 5,
Minimally invasive with an optical fiber Bragg grating force sensor, characterized in that it further comprises a circulator for passing the light emitted from the broadband light source to the measurement FBG side, the reflected light reflected from the measurement FBG to the wavelength measurement device side Surgical surgical system.
In the force measuring method using the surgical system for minimally invasive surgery of claim 5,
Light emitted from the broadband light source and incident to the plurality of optical fibers;
Light incident on the optical fiber is incident on the measurement FBG installed on each of the plurality of pillars of the surgical robot to reflect a specific wavelength;
Measuring the reflected wavelength of the light reflected by the measurement FBG in a wavelength measuring device in real time;
Measuring, by a photodiode, the amount of light passing through the wavelength measuring device;
The measurement FBG is also determined by deformation of the column when a force is applied to the joint end of the surgical robot based on the reflected wavelength measured in real time by the wavelength measuring device and the amount of light measured by the photodiode. The amount of wavelength change generated by deformation together is measured, and the strain of the pillar is calculated from the wavelength change, and the force and moment applied to the load cell provided between the joint and the pillar are measured from the strain to receive the joint end. Comprising a step of calculating the force in real time; Force measurement method using a surgical system for minimally invasive surgery with a fiber Bragg grating force sensor comprising a.
The method of claim 13,
The specific wavelength is reflected
Compensating the reflected wavelength according to the temperature of the compensation FBG provided in the pillar further comprises,
Before the step of reflecting the specific wavelength,
The coupler provided between the broadband light source and the measurement FBG further comprises the step of dispersing the light irradiated from the broadband light source in a plurality of paths, the surgical system for minimally invasive surgery with a fiber Bragg grating force sensor Force measurement method using.

Images