CN112419415A - Ultrasonic scanning method for realizing pose planning based on CRS curve fitting - Google Patents

Abstract

The invention relates to an ultrasonic scanning technology, and aims to provide an ultrasonic scanning method for realizing pose planning based on CRS curve fitting. The method comprises the following steps: scanning the chest contour of a patient, generating a scanning path, and obtaining the position and the set of road points which must pass through the scanning path; generating a control point set according to the road point set, and further constructing a vector space V; defining the distance between adjacent points to obtain a distance set D; generating a time parameter sequence based on the distance set; according to a CRS curve fitting interpolation method, obtaining a function of any point in a vector space V and a time parameter; and solving the pose at any moment, guiding the pose into a control execution component of the automatic ultrasonic scanning equipment, generating a self-adaptive scanning curve, and adjusting the pose of the scanning head in real time according to the actual condition of the patient. The pose planning process adopts Cartesian and quaternion space synchronous planning, and the principle is concise and understandable; compared with the traditional separated uniform spline-based interpolation algorithm and other algorithms, the method saves calculation power, and is simple and efficient. The invention can adapt to any complex scanning area to ensure that a global effective pose can be generated, and overlapping or invalid tracks in scanning are avoided; the scanning process is adaptive and efficient.

Description

Ultrasonic scanning method for realizing pose planning based on CRS curve fitting

Technical Field

The invention relates to an ultrasonic scanning technology, in particular to an ultrasonic scanning method for realizing pose planning based on CRS curve fitting (Centripetal Catmull-Romspline).

Background

Today, where robotics is increasingly incorporated into the medical field, medical robots that master automated navigation and planning techniques are becoming more and more widely used. The automatic planning of the ultrasonic scanning becomes an important technical reserve for relieving the pressure of doctors and patients, balancing medical resources and improving the screening and general inspection efficiency in primary medical treatment.

In the ultrasonic scanning technology, the pose planning of a complex scanning curved surface is the key for effectively finishing automatic scanning of each part and comprehensive screening of tumors. However, the various types of patients and intricate scanning areas present significant challenges to automated scanning techniques. For example, how to automatically generate universal and efficient scanning pose curves under the condition of multiple patients with different positions and sizes of mammary glands and thyroid glands. These practical problems exacerbate the complexity of automatic scanning trajectory planning, and especially the generation of efficient and universally applicable pose interpolation method is challenging.

Through the document retrieval in the prior art, the conventional pose planning method does not carry out research and optimization work aiming at the problem of locally inefficient pose planning in a complex curved surface. The existing track planning methods (such as a track planning method based on cubic uniform spline interpolation and a track planning method based on Bezier curve interpolation) can not ensure that problems of low-efficiency tracks, pose overlapping/pose circling and the like do not occur in the planning process.

Therefore, it is necessary to provide an improved pose planning method to realize complex scanning tasks and make them universal and efficient.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects in the prior art and provides an ultrasonic scanning method for realizing pose planning based on CRS curve fitting.

In order to solve the technical problems, the invention adopts the following solution:

the ultrasonic scanning method for realizing pose planning based on CRS curve fitting comprises the following steps:

(1) scanning the chest contour of a patient, generating a scanning path L, obtaining poses Pi of n waypoints which must pass through the scanning path L, wherein the poses Pi is { xi, yi, zi, ai, bi, ci and di }, and obtaining a waypoint set P is { P1, P2, …, Pi, … Pn };

(2) generating a control point set C ═ { C1, C2, …, Ci …, Cn +1, Cn +2} according to the waypoint set P; wherein Ci-Pi-1, i-2, 3, …, n + 1; c1 ═ 2C2-C3, …, Cn +2 ═ 2Cn + 1-Cn;

(3) constructing a vector space V epsilon R4 according to a control point set C { C1, C2, …, Cn +1 and Cn +2 };

(4) defining the distance between adjacent points vi +1 and vi in the vector space V as Di, and obtaining a distance set D { D1, D2, …, Dn +1}, wherein Di is ((xi +1-xi) ^2+ (yi +1-yi) ^2+ (zi +1-zi) ^2+ (alpha i + 1-alpha i) ^2) ^ 0.25; wherein i is 1, …, n +1, and ^ represents an exponentiation;

(5) generating a time parameter T sequence T ═ T1, T2, … and Tn +2} based on the distance set D ═ { D1, D2, … and Dn +1 }; wherein, Ti is D1+ … + Di-1, i is 2, …, n + 2; when i is 1, T1 is 0;

(6) obtaining a function F (Tr) -vr of any point vr and a time parameter Tr in a vector space V according to a CRS curve fitting interpolation method;

(7) solving the pose P (tr) corresponding to the condition that any time tr meets T1< tr < tn by using the time sequence T, the control point set C and the function F (Tr);

(8) and (3) leading the pose P (tr) into a control execution component of the automatic ultrasonic scanning equipment, and synchronously generating a self-adaptive scanning curve in Cartesian and quaternion spaces according to the specific geometric characteristic interpolation of the breast of the patient, so that the scanning execution component can adjust the pose of a scanning head in real time according to the actual condition of the patient, and the scanning adaptivity and the scanning efficiency are ensured.

In the present invention, in step (1), the pose Pi ═ { Pi, qi ═ { xi, yi, zi, ai, bi, ci, di }, i ═ 1,2,3, …, n; wherein xi, yi, zi, ai, bi, ci, di are real numbers; pi ═ { xi, yi, zi } denotes the location of each waypoint; qi ═ ai, bi, ci, di ═ ai + bi × i + ci × j + di × k is a unit quaternion, and represents the posture of each waypoint; let qi be the real part of the quaternion qi, and qi be the imaginary part of the quaternion qi.

In the present invention, in step (3), the vector space V includes a point set V ═ V1, V2, …, vi …, vn +2}, vi ═ xi, yi, zi, α i }, i ═ 1,2,3 … … n + 2; wherein xi, yi and zi represent the coordinates of the control point Ci in the x, y and z axes of a Cartesian coordinate system, and α i represents the rotation angle s between quaternions qi-1 and qi representing the postures of adjacent control points Ci-1 and Ci; the formula for α i is 2 × acos ((inv (qi-1) × qi). w), i is 2,3, …, n + 2; when i is 1, α 1 is 0; inv () represents the inversion operation on a quaternion.

In the present invention, in the vector space V in step (6), an arbitrary time variable Tr satisfying Ti < Tr < Ti +1, i ═ 2, …, n is interpolated with a point set V according to the time series T to obtain a point f (Tr) ═ vr ═ xr, yr, zr, α r } ∈ V; wherein Ak and Bj are reference variables;

Ak＝(Tk-Tr)/(Tk-Tk-1)×vk-1+(Tr-Tk-1)/(Tk-Tk-1)×vk；k＝i,i+1,i+2；

Bj＝(Tj+1-Tr)/(Tj+1-Tj-1)×Aj+(Tr-Tj-1)/(Tj+1-Tj-1)×Aj+1；j＝i,i+1；

then, f (Tr) ═ vr ═ Ti +1-Tr)/(Ti +1-Ti) × Bi + (Tr-Ti)/(Ti +1-Ti) × Bi + 1.

In the present invention, in step (7), it is assumed that the scanning path L passes through the waypoints P ═ P1, P2, …, Pn from time t1 to time tn; then for any time tr, t1< tr < tn is satisfied, and its corresponding pose p (tr) satisfies the following relationship:

tr ═ Tn +1-T2 × (Tr-T1)/(Tn-T1) + T2, satisfying Ti < Tr < Ti + 1;

using the function f (tr) we obtain: v (tr) ═ f (tr) { xr, yr, zr, α r };

calculating a quaternion qc ═ sin (α i +1- α r)/sin (α i +1) × qi + sin (α r)/sin (α i +1) × qi + 1;

q is qi × qc is { ar, br, cr, dr }, so far, p (tr) is { xr, yr, zr, ar, br, cr, dr }.

Compared with the prior art, the invention has the technical effects that:

1. the pose planning process adopts Cartesian and quaternion space synchronous planning, and the principle is concise and understandable; compared with the traditional separated uniform spline-based interpolation algorithm and other algorithms, the method saves calculation power, and is simple and efficient.

2. The pose planning process can be suitable for any complex scanning area to ensure that a global effective pose can be generated, and overlapping or invalid tracks are avoided in scanning; the scanning process is adaptive and efficient.

Drawings

Fig. 1 is a schematic diagram of the process of planning the position scanning pose of the invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

An ultrasonic scanning method for realizing pose planning based on CRS curve fitting comprises the following steps:

(1) scanning the chest contour of a patient, generating a scanning path L, obtaining the poses Pi of n waypoints which must pass through the scanning path L, wherein the poses Pi is { xi, yi, zi, ai, bi, ci, di }, the Pi, qi }, the i is 1,2,3, …, n, and obtaining a waypoint set P is { P1, P2, …, Pi, … Pn }; wherein xi, yi, zi, ai, bi, ci, di are real numbers; pi ═ { xi, yi, zi } denotes the location of each waypoint; qi ═ ai, bi, ci, di ═ ai + bi × i + ci × j + di × k is a unit quaternion, and represents the posture of each waypoint; let qi be the real part of the quaternion qi, and qi be the imaginary part of the quaternion qi.

(2) Generating a control point set C ═ { C1, C2, …, Ci …, Cn +1, Cn +2} according to the waypoint set P; wherein Ci-Pi-1, i-2, 3, …, n + 1; c1 ═ 2C2-C3, …, Cn +2 ═ 2Cn + 1-Cn;

(3) constructing a vector space V epsilon R4 according to a control point set C { C1, C2, …, Cn +1 and Cn +2 };

the vector space V contains a set of points V ═ { V1, V2, …, vi …, vn +2}, vi ═ xi, yi, zi, α i }, i ═ 1,2,3 … … n + 2; wherein xi, yi and zi represent the coordinates of the control point Ci in the x, y and z axes of a Cartesian coordinate system, and α i represents the rotation angle s between quaternions qi-1 and qi representing the postures of adjacent control points Ci-1 and Ci; the formula for α i is 2 × acos ((inv (qi-1) × qi). w), i is 2,3, …, n + 2; when i is 1, α 1 is 0; inv () represents the inversion operation on a quaternion.

(4) Defining the distance between adjacent points vi +1 and vi in the vector space V as Di, and obtaining a distance set D { D1, D2, …, Dn +1}, wherein Di is ((xi +1-xi) ^2+ (yi +1-yi) ^2+ (zi +1-zi) ^2+ (alpha i + 1-alpha i) ^2) ^ 0.25; wherein i is 1, …, n +1, and ^ represents an exponentiation;

(5) generating a time parameter T sequence T ═ T1, T2, … and Tn +2} based on the distance set D ═ { D1, D2, … and Dn +1 }; wherein, Ti is D1+ … + Di-1, i is 2, …, n + 2; when i is 1, T1 is 0;

(6) obtaining a function F (Tr) -vr of any point vr and a time parameter Tr in a vector space V according to a CRS curve fitting interpolation method;

in the vector space V, according to the time series T, for an arbitrary time variable Tr satisfying Ti < Tr < Ti +1, i ═ 2, …, n, an interpolation is performed with the point set V to obtain a point f (Tr) ═ vr ═ xr, yr, zr, α r } ∈ V; wherein Ak and Bj are reference variables;

Ak＝(Tk-Tr)/(Tk-Tk-1)×vk-1+(Tr-Tk-1)/(Tk-Tk-1)×vk；k＝i,i+1,i+2；

Bj＝(Tj+1-Tr)/(Tj+1-Tj-1)×Aj+(Tr-Tj-1)/(Tj+1-Tj-1)×Aj+1；j＝i,i+1；

then, f (Tr) ═ vr ═ Ti +1-Tr)/(Ti +1-Ti) × Bi + (Tr-Ti)/(Ti +1-Ti) × Bi + 1.

(7) Solving the pose P (tr) corresponding to the condition that any time tr meets T1< tr < tn by using the time sequence T, the control point set C and the function F (Tr);

assuming that the scanning path L starts from time t1 to time tn, and passes through the waypoints P ═ P1, P2, …, Pn, respectively; then for any time tr, t1< tr < tn is satisfied, and its corresponding pose p (tr) satisfies the following relationship:

tr ═ Tn +1-T2 × (Tr-T1)/(Tn-T1) + T2, satisfying Ti < Tr < Ti + 1;

using the function f (tr) we obtain: v (tr) ═ f (tr) { xr, yr, zr, α r };

calculating a quaternion qc ═ sin (α i +1- α r)/sin (α i +1) × qi + sin (α r)/sin (α i +1) × qi + 1;

q ═ qi × qc ═ { ar, br, cr, dr }, so far, p (tr) ═ { xr, yr, zr, ar, br, cr, dr };

(8) and (3) leading the pose P (tr) into a control execution component of the automatic ultrasonic scanning equipment, and synchronously generating a self-adaptive scanning curve in Cartesian and quaternion spaces according to the specific geometric characteristic interpolation of the breast of the patient, so that the scanning execution component can adjust the pose of a scanning head in real time according to the actual condition of the patient, and the scanning adaptivity and the scanning efficiency are ensured.

Claims (5)

1. An ultrasonic scanning method for realizing pose planning based on CRS curve fitting is characterized by comprising the following steps:

(1) scanning the chest contour of a patient, generating a scanning path L, obtaining poses Pi of n waypoints which must pass through the scanning path L, wherein the poses Pi is { xi, yi, zi, ai, bi, ci and di }, and obtaining a waypoint set P is { P1, P2, …, Pi, … Pn };

(2) generating a control point set C ═ { C1, C2, …, Ci …, Cn +1, Cn +2} according to the waypoint set P; wherein Ci-Pi-1, i-2, 3, …, n + 1; c1 ═ 2C2-C3, …, Cn +2 ═ 2Cn + 1-Cn;

(3) constructing a vector space V epsilon R4 according to a control point set C { C1, C2, …, Cn +1 and Cn +2 };

(4) defining the distance between adjacent points vi +1 and vi in the vector space V as Di, and obtaining a distance set D as { D1, D2, …, Dn +1}, wherein Di is ((xi +1-xi) ^2+ (yi +1-yi) ^2+ (zi +1-zi) ^2+ (alpha i + 1-alpha i) ^2) ^ 0.25; wherein i is 1, …, n +1, and ^ represents an exponentiation;

(5) generating a time parameter T sequence T ═ T1, T2, … and Tn +2} based on the distance set D ═ { D1, D2, … and Dn +1 }; wherein, Ti is D1+ … + Di-1, i is 2, …, n + 2; when i is 1, T1 is 0;

(6) obtaining a function F (Tr) -vr of any point vr and a time parameter Tr in a vector space V according to a CRS curve fitting interpolation method;

(7) solving the pose P (tr) corresponding to the condition that any time tr meets T1< tr < tn by using the time sequence T, the control point set C and the function F (Tr);

(8) and (3) leading the pose P (tr) into a control execution component of the automatic ultrasonic scanning equipment, and synchronously generating a self-adaptive scanning curve in Cartesian and quaternion spaces according to the specific geometrical characteristic interpolation of the breast of the patient, so that the scanning execution component can adjust the pose of a scanning head in real time according to the actual condition of the patient.

2. The method according to claim 1, characterized in that in step (1), the pose Pi ═ { Pi, qi } ═ { xi, yi, zi, ai, bi, ci, di }, i ═ 1,2,3, …, n; wherein xi, yi, zi, ai, bi, ci, di are real numbers; pi ═ { xi, yi, zi } denotes the location of each waypoint; qi ═ ai, bi, ci, di ═ ai + bi × i + ci × j + di × k is a unit quaternion, and represents the posture of each waypoint; let qi be the real part of the quaternion qi, and qi be the imaginary part of the quaternion qi.

3. The method according to claim 1, wherein in step (3), the vector space V contains a set of points V ═ { V1, V2, …, vi …, vn +2}, vi ═ xi, yi, zi, α i }, i ═ 1,2,3 … … n + 2; wherein xi, yi and zi represent the coordinates of the control point Ci in the x, y and z axes of a Cartesian coordinate system, and α i represents the rotation angle s between quaternions qi-1 and qi representing the postures of adjacent control points Ci-1 and Ci; the formula for α i is 2 × acos ((inv (qi-1) × qi). w), i is 2,3, …, n + 2; when i is 1, α 1 is 0; inv () represents the inversion operation on a quaternion.

4. The method according to claim 1, wherein in step (6), in the vector space V, for any time variable Tr satisfying Ti < Tr < Ti +1, i ═ 2, …, n, a point f (Tr) ═ vr ═ xr, yr, zr, α r } ∈ V is interpolated from a set of points V according to a time series T; wherein Ak and Bj are reference variables;

Ak＝(Tk-Tr)/(Tk-Tk-1)×vk-1+(Tr-Tk-1)/(Tk-Tk-1)×vk；k＝i,i+1,i+2；

Bj＝(Tj+1-Tr)/(Tj+1-Tj-1)×Aj+(Tr-Tj-1)/(Tj+1-Tj-1)×Aj+1；j＝i,i+1；

then, f (Tr) ═ vr ═ Ti +1-Tr)/(Ti +1-Ti) × Bi + (Tr-Ti)/(Ti +1-Ti) × Bi + 1.

5. The method of claim 1, wherein in step (7), the scanning path L is assumed to start from time t1 to end at tn, passing through waypoints P ═ P1, P2, …, Pn, respectively; then for any time tr, t1< tr < tn is satisfied, and its corresponding pose p (tr) satisfies the following relationship:

tr ═ Tn +1-T2 × (Tr-T1)/(Tn-T1) + T2, satisfying Ti < Tr < Ti + 1;

using the function f (tr) we obtain: v (tr) ═ f (tr) { xr, yr, zr, α r };

calculating a quaternion qc ═ sin (α i +1- α r)/sin (α i +1) × qi + sin (α r)/sin (α i +1) × qi + 1;

q is qi × qc is { ar, br, cr, dr }, so far, p (tr) is { xr, yr, zr, ar, br, cr, dr }.

Images