# US 12,005,591 B2 · Ultrasonic testing system of dual robot arms and method thereof

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- Number: US 12,005,591 B2
- Document ID: US12005591B2
- Status: Granted
- Kind: B2
- Application number: 17/051,072
- Filed: 2019-07-16
- Published: 2021-10-21
- Granted: 2024-06-11
- Earliest claimed: 2018-07-16
- Assignees: Beijing Institute of Technology
- Applicants: Beijing Institute of Technology
- Inventors: Chunguang Xu; Canzhi Guo; Juan Hao; Wanxin Yang; Xianchun Xu; Ruili Jia; Xinhao Zheng
- Web page: https://patentgrep.com/patent/US12005591B2

## CPC

- B25J 9/1682: {Dual arm manipulator; Coordination of several manipulators}
- B25J 9/1692: {Calibration of manipulator}
- B25J 9/0087: {Dual arms (double SCARA arms B25J9/043)}
- G01N 29/04: Analysing solids (using acoustic emission techniques G01N29/14)
- G01N 29/041: {on the surface of the material, e.g. using Lamb, Rayleigh or shear waves}
- G01N 29/043: {in the interior, e.g. by shear waves}
- G01N 29/225: {Supports, positioning or alignment in moving situation}
- G01N 29/265: by moving the sensor relative to a stationary material
- G01N 29/28: providing acoustic coupling {, e.g. water (impedance matching G10K11/02)}
- G01N 2291/0289: Internal structure, e.g. defects, grain size, texture
- G01N 2291/044: Internal reflections (echoes), e.g. on walls or defects
- G01N 2291/045: External reflections, e.g. on reflectors
- G01N 2291/102: one emitter, one receiver
- G01N 2291/2698: Other discrete objects, e.g. bricks
- G05B 2219/39109: Dual arm, multiarm manipulation, object handled in cooperation
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

An ultrasonic testing system of dual robot arms and an ultrasonic testing method for use in testing quality of surface and interior of a workpiece. The system includes an extension rod provided between a tail-end of a master robot arm and an emitting probe and/or between a tail-end of a slave robot arm and a receiving probe. One or more connected extension rod rotating shafts is provided between the extension rod and the emitting probe or between the extension rod and the receiving probe. The method uses an X-axis constraint method to convert posture data of the discrete points in a trajectory file of the tested workpiece into Euler angles, and constrain the X-axes of the auxiliary coordinate systems at the same time so that the positive direction of the X-axis of each of the auxiliary coordinate systems is the trajectory tangent direction.

## Claims

### Claim 1

An ultrasonic testing method by using an ultrasonic testing system of dual robot arms, comprising:
a step 1 of calibrating a coordinate system of a tested workpiece for the ultrasonic testing system of dual robot arms, and determining relationships of the coordinate system of the tested workpiece relative to base coordinate systems of the master and slave robot arms;
a step 2 of performing a trajectory planning on the tested workpiece to generate a trajectory file of discrete points of the coordinate system of the tested workpiece; the trajectory file including coordinates and posture data;
a step 3 of building auxiliary coordinate systems in the coordinate system of the workpiece, using a X-axis constraint method to constrain the X-axes of the auxiliary coordinate systems so that a positive direction of the X-axis of each of the auxiliary coordinate systems is a tangent direction of the trajectory, and using the X-axis constraint method to convert the posture data of the discrete points generated in the step 2 into Euler angles;
a step 4 of converting the coordinates of the discrete points generated in the step 3 and the converted Euler angles of the discrete points in the step 3 into coordinates and Euler angles of the base coordinate systems of the master and slave robot arms according to the relationships among the coordinate system of the workpiece and base coordinate systems of the master and slave robot arms, and then downloading the resulting coordinates and the Euler angles to the master and slave robot arm controllers, respectively;
a step 5 of inputting transformation relationship of a tool coordinate system of the master robot arm relative to a flange coordinate system of the master robot arm to the master robot arm controller, and inputting transformation relationship of the tool coordinate system of the slave robot arm in relative to a flange coordinate system of the slave robot arm to the slave robot arm controller; and
a step 6 of bringing the testing system of dual robot arms into an operating state, and controlling, by the master and slave robot arm controllers respectively, the master and slave robot arms having the probes to comprehensively test the tested workpiece.

### Claim 2 (depends on 1)

The ultrasonic testing method as claimed in claim 1, wherein the step of using the X-axis constraint method to constrain the X-axes of the auxiliary coordinate systems includes:
building an imaginary X-axis for each of the auxiliary coordinate systems in the coordinate system of the workpiece so that the imaginary X-axis is in a secant direction of the trajectory, and by taking two points b(xb, yb, zb) and c(xc, yc, zc) on the imaginary X-axis, expressing a vector of the imaginary X-axis as: ox′=(xc−xb, yc−yb, zc−zb),
setting a Z-axis of each of the auxiliary coordinate systems as a cutter shaft vector of each of the point b and expressing its vector as:
oz=(tx,ty,tz)
obtaining a vector of a Y-axis for each of the auxiliary coordinate systems by the following equation:
oy
=
⁢
oz
×
ox
′
=
⁢
(
t
y
⁡
(
z
c
-
z
b
)
-
t
z
⁡
(
y
c
-
y
b
)
,
t
z
⁢
(
x
c
-
x
b
)
-
(
t
x
⁡
(
z
c
-
z
b
)
,
⁢
t
x
⁡
(
y
c
-
y
b
)
-
t
y
⁡
(
x
c
-
x
b
)
)
=
⁢
(
oy
x
,
oy
y
,
oy
z
)
obtaining the vector of the corrected X-axis for each of the auxiliary coordinate systems by a cross product of oy and oz in order to be in a tangent direction of the trajectory, wherein the equation of the cross product is as follows:
ox
=
⁢
oy
×
oz
=
⁢
(
(
t
z
⁡
(
x
c
-
x
b
)
-
t
x
⁡
(
z
c
-
z
b
)
)
⁢
(
z
c
-
z
b
)
-
(
t
x
⁡
(
y
c
-
y
b
)
-
t
y
⁡
(
x
c
-
x
b
)
)
⁢
(
y
c
-
y
b
)
,
(
t
x
⁡
(
y
c
-
y
b
)
-
t
y
⁡
(
x
c
-
x
b
)
)
⁢
(
x
c
-
x
b
)
-
(
t
y
⁡
(
z
c
-
z
b
)
-
t
z
⁡
(
y
c
-
y
b
)
)
⁢
(
z
c
-
z
b
)
,
(
t
y
⁡
(
z
c
-
z
b
)
-
t
z
⁡
(
y
c
-
y
b
)
)
⁢
(
y
c
-
y
b
)
-
(
t
z
⁡
(
x
c
-
x
b
)
-
t
x
⁡
(
z
c
-
z
b
)
)
⁢
(
x
c
-
x
b
)
)
=
⁢
(
o
⁢
x
x
,
o
⁢
x
y
,
o
⁢
x
z
)
.

### Claim 3 (depends on 2)

The ultrasonic testing method as claimed in claim 2, wherein the converting step of the Euler angles in the step 3 includes obtaining the Euler angles of the coordinate system of the workpiece based on the equal relationship between an Euler angle transformation matrix and a rotation matrix:
α=A tan 2(−py,pz)×180/π
β=A tan 2(px,√{square root over (py2+pz2)})×180/π
γ=A tan 2(−ny,nx)×180/π,
wherein
p
x
=
t
x
t
x
2
+
t
y
2
+
t
z
2
;
p
y
=
t
y
t
x
2
+
t
y
2
+
t
z
2
;
p
z
=
t
z
t
x
2
+
t
y
2
+
t
z
2
;
n
y
=
o
⁢
x
y
o
⁢
x
x
2
+
o
⁢
x
y
2
+
o
⁢
x
z
2
;
n
x
=
ox
x
o
⁢
x
x
2
+
o
⁢
x
y
2
+
o
⁢
x
z
2
.