CN104224089A - Endoscope system with anti-interference capacity and surgical navigation function - Google Patents

Abstract

The invention provides an endoscope system with an anti-interference capacity and a surgical navigation function. A surgical navigation subsystem is realized by an inertial navigation module, and the inertial navigation module comprises three sensors, i.e., a triaxial accelerometer, a triaxial gyroscope and a triaxial magnetometer. Depending on a micro-electro-mechanical system technique, the navigation subsystem can be integrated in a handle of an endoscope, so that the endoscope has a positioning function. In a positioning algorithm, through proper anti-interference treatment, positioning errors caused by external magnetic fields and movement of the endoscope are reduced, and the positioning stability and accuracy are improved.

Description

A kind of endoscopic system with surgical navigational function possessing capacity of resisting disturbance

Technical field

The invention belongs to computer assisted endoscopic surgery field of navigation technology.

Background technology

Along with the development of modern medicine, the Minimally Invasive Surgery being main implementation tool with endoscopic system has been widely recognized and popularizes fast.In order to reach the object of Wicresoft better, doctor must obtain attitude and the position of current endoscope accurately, therefore usually needs by location of operation and airmanship.Therefore, modern Endoscopy and medical navigation technology are complementary, also usually need two cover systems simultaneously to cooperatively interact at intra-operative.

No. CN200910198524, Chinese patent discloses one " device be combined operation guiding system with endoscopic system and application thereof ", this patent gives a kind of method combined with endoscope by optical positioning system: by special frame for movement, is fixed in endoscope handle by optical alignment ball.In use, need be followed the tracks of optical alignment ball by shooting unit, thus the object of endoscope location.

There are the following problems in actual applications for above-mentioned patent: one, the introducing of frame for movement causes the volume of endoscope handle part greatly to increase, and may bring impact to normal endoscopic technic.Two, optical alignment needs to ensure to there is unscreened sight line between video camera and place kick in principle, this condition by the orientation range of restriction system, may produce multiple can not locating area.Three, optical alignment needs to complete location tasks by multiple video camera in principle, and this will bring unnecessary space pressure to operating room.

Summary of the invention

The object of the invention is the problems referred to above solving prior art existence, a kind of endoscopic system with surgical navigational function possessing capacity of resisting disturbance is provided.

First, this system is by being integrated in endoscope system inside by the positioning subsystem be made up of inertial navigation module, overcome the impact of positioning subsystem on endoscopic technic, and eliminate in optical alignment can not locating area, it also avoid the space pressure that optical alignment brings simultaneously.On the other hand, for inertial navigation self, the non-inertia motion of the electronic equipment in work space and irony apparatus and endoscope all directly can have influence on precision and the stability of location, therefore the present invention is in algorithm realization part, there is provided corresponding Anti-interference Design, to improve the robustness of location.

The endoscopic system with surgical navigational function possessing capacity of resisting disturbance provided by the invention comprises, the host computer of endoscope and responsible control and positioning calculation, navigation module mounting platform is reserved with in described endoscope handle, by the inertial navigation module be installed on after micro electronmechanical minimization on the inner mounting platform of endoscope handle, inertial navigation module comprises three axis accelerometer, three-axis gyroscope and three axis magnetometer three kinds of sensors, and with the SOC(system on a chip) of radio communication function and miniature antenna, SOC(system on a chip) gathers the sensing data that three kinds of sensors export, and rely on miniature antenna that sensing data is sent to host computer, described host computer comprises computer, with the SOC(system on a chip) of radio communication function and antenna, with the sensing data that the SOC(system on a chip) of radio communication function is exported by antenna reception inertial navigation module, and sensing data packing is transferred to computer, computer is positioned by the location algorithm designed and resolves.

Location algorithm in described computer possesses capacity of resisting disturbance, can suppress the sensor output noise that the non-inertia motion of the distortion of field and endoscope brings; When being restrained with the attitude than force vector endoscope by ground magnetic vector, the relative error export ground magnetic vector and the relative error that exports than force vector are as the weight of Convergence monitoring function, to adjust convergence direction, obtain attitude convergence result adaptively; Be linear acceleration, acceleration of gravity and centripetal acceleration three by the output of gyroscope and accelerometer by specific force resolution of vectors, and by carrying out quadratic integral to linear acceleration, obtain position result.

In concrete enforcement, the inertial navigation system being conventionally used to carrier navigation is applied to location of operation field by this method.The micro electro mechanical inertia sensing unit be made up of three-axis gyroscope, three axis accelerometer and three axis magnetometer is fixed on endoscope handle inside, to obtain sensing data.Sensing data is transferred to host computer by communication again, and host computer, by algorithm realization, carries out full dimension location.Location algorithm can be roughly divided into two steps.The first step, is exported by gyroscope and upgrades attitude, and is exported by accelerometer and export restrain attitude quaternion with gaussmeter.In convergence process, exported by acceleration measurement meter and relative error that gaussmeter exports, control acceleration and the ground weight of magnetic vector in convergence process, to obtain the Adaptive Attitude result possessing noiseproof feature.Second step, based on the attitude result obtained, and accelerometer and gyrostatic output, by building rigid block element, the position of three dimensionality is resolved.This part does not directly utilize magnetic survey result, therefore can avoid possible magnetic disturbance further.

Advantage of the present invention and good effect:

For the bottleneck of publication existence, inertia sensing is introduced medical navigation field by the present invention, and the inertia sensing module by micro-electromechanical technology minimization is mounted to endoscope handle inside.Specific force, angular velocity and ground magnetic vector is measured in real time by acceleration, gyroscope and gaussmeter; Collected sensing data sends to host computer by radio communication, and is resolved the real-time attitude and position that obtain endoscope by algorithm.

Navigation system is embedded in endoscope system inside by the present invention, can't change the profile of endoscope, therefore prevents navigation system on the impact of endoscope system.Meanwhile, there is not the sight line demand in optical alignment in inertial navigation, and without the need to arranging ancillary equipment (the shooting unit etc. as in optical positioning system) again, alleviate the space pressure of operating room.

(1) clinical dilemma of traditional operation air navigation aid is overcome.Traditional operation air navigation aid comprises optical alignment and electromagnetic location.The former has strict sight line requirement, and the latter needs the strict electromagnetic interference source controlling work space.These 2 is unapproachable at the surgical environments of reality.But inertial navigation can effectively avoid these problems: on the one hand, inertia system is not in use subject to the restriction of sighting condition; On the other hand, the fusion of many heat transfer agents can reduce the dependence of system to magnetic sensing, and by effective algorithm design, system can be weakened further to the response of noise.Finally, a set of location of operation system that can be used in the stable output of full extent of space can be built.

(2) endoscope system does not interfere with each other mutually with navigation system.Due in this device, navigation system is installed in the inside of endoscopic system, can't change the profile of endoscope, thus can not make troubles to the operation of doctor.Meanwhile, in total space arbitrary motion, can can't there is in optical positioning system the problem of blocking and observing sight line in endoscope system.

(3) capacity of resisting disturbance is strong, and robustness is high.System introduces inertia sensing, is improved the stability of system by information fusion technology.In fusion process, taking into account the relative error of accelerometer output by observing magnetic strength, investigating the credibility of information source.According to relative error size, the direction of control convergence and degree, obtain the adaptive optimum attitude solution of noise.To sum up, realized by the method for hardware and software aspect, improve the robustness of entire system as much as possible.

(4) real-time is good, strong adaptability.Relative to the published inertial positioning method with noiseproof feature, this method avoids complicated filtering, reduce algorithm complex, to obtain better real-time.Meanwhile, this method does not need prior calibration process, thus it also avoid the problem that need repeat when changing environment for use to demarcate, improve the adaptability of system to varying environment.

Accompanying drawing explanation

Fig. 1 is the system composition frame diagram of location of operation system.

Fig. 2 is the mounting means schematic diagram of navigation elements, and in figure, 1 is endoscope's (locally), and 2 for being installed on the inertia sensing unit of endoscope handle.

Fig. 3 is the overall flow figure of the adaptive tracking method based on sensing fusion.

Detailed description of the invention

Embodiment 1:

As depicted in figs. 1 and 2, the endoscopic system with surgical navigational function possessing capacity of resisting disturbance provided by the invention comprises, the host computer of endoscope and responsible control and positioning calculation, navigation module mounting platform is reserved with in described endoscope handle, by the inertial navigation module be installed on after micro electronmechanical minimization on the inner mounting platform of endoscope handle, inertial navigation module comprises three axis accelerometer, three-axis gyroscope and three axis magnetometer three kinds of sensors, and with the SOC(system on a chip) of radio communication function and miniature antenna, SOC(system on a chip) gathers the sensing data that three kinds of sensors export, and rely on miniature antenna that sensing data is sent to host computer, described host computer comprises computer, with the SOC(system on a chip) of radio communication function and antenna, with the sensing data that the SOC(system on a chip) of radio communication function is exported by antenna reception inertial navigation module, and sensing data packing is transferred to computer, computer is positioned by the location algorithm designed and resolves.

The present invention, before endoscope handle has been assembled, processes a size and inertial navigation module consistent size therein, both sides respectively with the rectangular recess that endoscope pipe is parallel or vertical, as the mounting platform of the inertial navigation module of rectangle.

Inertial sensor unit is fixed on endoscope handle inside by the present invention in a specific way, adopts SOC(system on a chip) to gather sensing data by wireless communication transmissions to host computer.Host computer carries out the location compute of 6DOF by the algorithm that the present invention proposes, to realize the real-time positioning navigation of endoscope.Algorithm part, is exported by three-axis gyroscope and carries out according to a preliminary estimate attitude, and is measured attitude respectively by three axis magnetometer and three axis accelerometer output, and convergence estimate value, to obtain attitude measurement value.In convergence process, gaussmeter exports and exports with the relative error of acceleration of gravity as adaptive factor with the relative error in earth's magnetic field and accelerometer, and judge the size of noise, adjustment restrains weight, obtains self adaptation convergence result.After obtaining real-time attitude result, each output component of separate accelerometer, to build the kinesiology differential equation.And then, resolve linear acceleration components, and about the time, numerical integration is carried out to it, obtain current location.

One, system hardware is formed

Please as shown in Figure 1, system is divided into two parts on hardware.Part I is the sensor unit being installed on endoscope handle inside; It is made up of sensor module, wireless transmitting module and miniature antenna.Sensor module comprises three micro-electro-mechanical sensors, i.e. accelerometer, gyroscope and gaussmeter.Wireless transmitting module is mainly a SOC(system on a chip) with wireless transmitting function.Part II is that responsible data are resolved and the host computer shown; It is made up of Communication Control center, wireless transmitting module and antenna.Communication control center is the maincenter of native system, is responsible for Systematical control and date processing.Wireless receiving module is also formed primarily of a SOC(system on a chip) with wireless transmitting function.

Please as shown in Figure 2, when navigation system being mounted to endoscope system and being inner, need the coordinate axes of two cover systems strictly to aim at.The principle of aiming at: the X-axis of sensor unit is parallel to endoscope's working lens pipe, the direction of Z axis perpendicular to endoscope's working lens pipe and dorsad handle.In order to reach aligning object, process the groove of rectangle in endoscope handle inside, its two length of side is consistent with two length of sides of the inertial navigation module of rectangle, as the mounting platform of inertial navigation module, mounting platform is while be parallel to scope working lens pipe, perpendicular to working lens pipe.Rectangular sensor unit circuitry plate is fixed on mounting platform by screw, aligns in its each limit respectively limit each with mounting platform.In order to ensure that sensor unit circuitry plate is adjacent to and mounting platform completely, the whole branch of all electronic components of circuit board is in circuit board one side.

Two, working-flow

During system works, wireless transmitting module passes through specific manner of communication, the output of pick-up transducers module, and it is launched to host computer by miniature antenna.After the wireless receiving module of host computer receives data by antenna, then send to Communication Control center, and resolved by it, obtain positioning result.Such as, can use and support that the SOC(system on a chip) of Zigbee protocol is as wireless transmitting module and wireless receiving module, and use Zigbee protocol as the communication mode between system two parts; Using desktop computer as Communication Control center; Wireless transmitting module communicates with I2C or SPI protocol with sensor module; Wireless receiving module communicates with usb protocol with Communication Control center.

Three, adaptive attitude positioning method

Overall positioning flow please as shown in Figure 3.The present invention uses gravitational vectors and the attitude quaternion of ground magnetic vector to sensor to restrain.In convergence process, export according to accelerometer and to export with the difference of acceleration of gravity and gaussmeter and the difference of absolute force assigns weight the factor.

If, for accelerometer is in the output of carrier coordinate system, for gaussmeter is in the output of carrier coordinate system; g ⁿfor accelerometer is in the output of reference frame, m ⁿfor gaussmeter is in the output of reference frame.

For accelerometer measures, relative to acceleration of gravity, linear acceleration and centripetal acceleration are in a small amount.The introducing of linear acceleration and centripetal acceleration significantly can't affect the direction of specific force, and the direction of specific force can regard as the direction of acceleration of gravity substantially.Therefore, only use scalar value to build relative error.That is:

$f_{\mathrm{adg}}=\left|\right|\frac{\left|\right|\widetilde{g^b}\left|\right|-\left|\right|g^n\left|\right|}{\left|\right|g^n\left|\right|}\left|\right|---\left(1\right)$

Magnetic intensity is measured.Magnetic distortion may be in the same order of magnitude with absolute force in size completely.The introducing of magnetic distortion significantly can affect the direction of total magnetic intensity.Therefore, jointly build relative error by size and two, direction factor.

Similar to acceleration magnitude error, magnetic intensity Size Error can be expressed as:

$f_{\mathrm{adm}1}=\left|\right|\frac{\left|\right|\widetilde{m^b}\left|\right|-\left|\right|m^n\left|\right|}{\left|\right|m^n\left|\right|}\left|\right|---\left(2\right)$

Magnetic intensity deflection error: consider that linear acceleration and centripetal acceleration do not affect the direction of specific force substantially, chooses the angle of magnetic intensity and specific force to describe the direction of magnetic intensity in reference frame and carrier coordinate system.In reference frame, this angle is designated as β ⁿ; In carrier coordinate system, consider the existence of distortion, this angle is designated as then,

${\mathrm{\β}}^n=\mathrm{ar}\cos (\frac{g^n}{\left|\right|g^n\left|\right|}\·\frac{m^n}{\left|\right|m^n\left|\right|})---\left(3\right)$

$\widetilde{{\mathrm{\β}}^b}=\mathrm{ar}\cos (\frac{\widetilde{g^b}}{\left|\right|\widetilde{g^b}\left|\right|}\·\frac{\widetilde{m^b}}{\left|\right|{\tilde{m}}^b\left|\right|})---\left(4\right)$

, magnetic intensity deflection error:

$f_{\mathrm{adm}2}=\left|\right|\frac{\widetilde{{\mathrm{\β}}^b}-{\mathrm{\β}}^n}{{\mathrm{\β}}^n}\left|\right|---\left(5\right)$

Total magnetic intensity error is:

f _adm＝k ₁·f _adm1+k ₂·f _adm2 (6)

In formula, k ₁with k ₂be two constant weight factors.Two numbers are empirical value, and meet:

k ₁+k ₂＝1 (7)

To sum up, adaptive error observation function is for shown in (8).When gravity measurement error is larger, f _adgcorresponding increase, makes magnetic survey item leading convergence process; In like manner, when magnetic survey error is larger, f _admcorresponding increase, makes gravity measurement item leading convergence process.

$E_{\mathrm{ad}}=f_{\mathrm{adm}}{(\widetilde{g^b}-\widehat{C_n^b}{g}^n)}^2+f_{\mathrm{adg}}{(\widetilde{m^b}-\widehat{C_n^b}{m}^n)}^2---\left(8\right)$

In formula, for the estimation of spin matrix.Can find out, for gravity measurement and magnetic survey, the side that noise is larger will account for back burner in convergence process, and error is larger, and its relative weighting is lower.Therefore this method can be disturbed the size of degree according to sensor, adjust adaptively, make result closer to optimal solution.

The convergence objective matrix corresponding with (8) is:

$F_{\mathrm{ab}}=\left[\begin{array}{c}\sqrt{f_{\mathrm{adm}}}(\widetilde{g^b}-\widehat{C_n^b}{g}^n)\\ \sqrt{f_{\mathrm{adg}}}(\widetilde{m^b}-\widehat{C_n^b}{m}^n)\end{array}\right]---\left(9\right)$

According to (10) (11) two formula, Gauss-Newton decline is carried out to (9) formula, convergence estimate hypercomplex number adaptive attitude result can be obtained.

${\hat{Q}}^{m+1}={\hat{Q}}^m-\mathrm{\&alpha;}<{\left[J_{\mathrm{ad}}^T\left({\hat{Q}}^m\right)J_{\mathrm{ad}}\left({\hat{Q}}^m\right)\right]}^{-1}{J}_{\mathrm{ad}}^T\left({\hat{Q}}^m\right)F_{\mathrm{ab}}\left({\hat{Q}}^m\right)>---\left(10\right)$

$J_{\mathrm{ad}}\left({\hat{Q}}_k^n\right)=\frac{{\mathrm{dF}}_{\mathrm{ab}}\left({\hat{Q}}_k^n\right)}{d{\hat{Q}}_k^n}---\left(11\right)$

Wherein, (10) relational expression that to be the m time iteration upgrade to the m+1 time iteration, α is iteration step length.

Four, location positioning method

The specific force of accelerometer exports containing linear acceleration, centripetal acceleration acceleration and acceleration of gravity three component compositions.Therefore, under carrier coordinate system, there is following relation:

$\widetilde{g^b}=a^b+{\mathrm{\&omega;}}^b\&times;v^b+\widehat{C_n^b}\&CenterDot;g^n---\left(12\right)$

Wherein, a ^bfor the linear acceleration of scope front end under carrier coordinate system.ω ^bthe i.e. output of gyroscope under carrier coordinate system, three axle components are ω _x, ω _yand ω _z; ω ^b× v ^bbe the centripetal acceleration of scope under carrier coordinate system.G ^bfor the acceleration of gravity under carrier coordinate system.

In the Attitude Tracking stage, having obtained real-time spin matrix is therefore g ^bcan be obtained by following relation:

$g^b=\widehat{C_n^b}\&CenterDot;g^n---\left(13\right)$

Linear acceleration is the differential of speed about the time, that is:

$a^b=\frac{\&PartialD;v^b}{\&PartialD;t}---\left(14\right)$

By (13) (14) two formula substitute into (12) formula, can obtain under carrier coordinate system, speed is about the differential equation of first order of time, as follows.

$\widetilde{g^b}=\frac{\&PartialD;v^b}{\&PartialD;t}+{\mathrm{\&omega;}}^b\&times;v^b+\widehat{C_n^b}\&CenterDot;g^n---\left(15\right)$

By (16) formula, velocity is gone out in reference frame following table,

$v^b=\widehat{C_n^b}\&CenterDot;v^n$

(16) formula is substituted into (15) formula, obtain velocity under reference frame and sensor export between mathematical relationship.

$\widetilde{g^b}=\widehat{C_n^b}\&CenterDot;\frac{\&PartialD;v^n}{\&PartialD;t}+{\mathrm{\&omega;}}^b\&times;(\widehat{C_n^b}\&CenterDot;v^n)+\widehat{C_n^b}\&CenterDot;g^n---\left(17\right)$

Again, under reference frame, position vector is the First-order Integral of speed about the time, namely

p ⁿ＝∫v ⁿ·dt (18)

On a locating periodically, numerical solution is carried out to (17) formula, and result is carried out discrete integration to speed by (18) formula on a locating periodically, can real-time update position vector.To sum up, the locating information of 6DOF can be obtained step by step according to above-mentioned two.

Facts have proved, in the size of magnetic distortion at earth's magnetic field size ± 25%, and specific force size is when acceleration of gravity ± 25%, and angle error in tracking can be controlled within 3.5 °, within location positioning error can be controlled in 3.5mm.Both all reach clinical practice requirement, possess desirable capacity of resisting disturbance and stability.

Claims (3)

1. one kind possesses the endoscopic system with surgical navigational function of capacity of resisting disturbance, comprise endoscope and be responsible for controlling the host computer with positioning calculation, it is characterized in that there is navigation module mounting platform at described endoscope handle internal reservation, by the inertial navigation module be installed on after micro electronmechanical minimization on the inner mounting platform of endoscope handle, inertial navigation module comprises three axis accelerometer, three-axis gyroscope and three axis magnetometer three kinds of sensors, and with the SOC(system on a chip) of radio communication function and miniature antenna, SOC(system on a chip) gathers the sensing data that three kinds of sensors export, and rely on miniature antenna that sensing data is sent to host computer, described host computer comprises computer, with the SOC(system on a chip) of radio communication function and antenna, with the sensing data that the SOC(system on a chip) of radio communication function is exported by antenna reception inertial navigation module, and sensing data packing is transferred to computer, computer is positioned by the location algorithm designed and resolves.

2. the endoscopic system with surgical navigational function possessing capacity of resisting disturbance according to claim 1, it is characterized in that the location algorithm in described computer possesses capacity of resisting disturbance, the sensor output noise that the non-inertia motion of the distortion of field and endoscope brings can be suppressed; When being restrained with the attitude than force vector endoscope by ground magnetic vector, the relative error export ground magnetic vector and the relative error that exports than force vector are as the weight of Convergence monitoring function, to adjust convergence direction, obtain attitude convergence result adaptively; Be linear acceleration, acceleration of gravity and centripetal acceleration three by the output of gyroscope and accelerometer by specific force resolution of vectors, and by carrying out quadratic integral to linear acceleration, obtain position result.

3. the endoscopic system with surgical navigational function possessing capacity of resisting disturbance according to claim 1 and 2, it is characterized in that before endoscope handle has been assembled, process a size and inertial navigation module consistent size therein, both sides respectively with the rectangular recess that endoscope pipe is parallel or vertical, as the mounting platform of the inertial navigation module of rectangle.