FIELD OF THE INVENTION
The invention relates generally to the field of non-destructive testing.
BACKGROUND
In the field of non-destructive testing (NDT), and in particular ultrasonic non-destructive testing, it is known to use scanners that survey a large surface area by being moved across the surface area. It can be difficult to keep track of which parts of the surface have been scanned. When performing area scanning (non-destructive examination) a defined surface needs to be covered. The probes (sensing device) used to inspect the area having a smaller surface than the area to be scanned, it is important that the scanning device is tracked so as to provide and guaranty a full surface coverage exempt of gap, and a precise position for every measurement point.
Prior art systems have required manual scanner head adjustment or stitching operations on the acquired non-destructive test data. Two axis encoders are also known, but have not been precise and did not measure device orientation relative to the article being inspected.
A prior art rectangular scanning support is shown in FIG. 1. A rectangular scanning support 20, supporting a scanning head 10 can be operated on a limited and defined surface. It is cumbersome to install and cannot inspect any area outside of the surface 30 defined by the frame. Thus scanning the entire inspection surface 40 becomes a cumbersome task of piecing together several scans of the limited coverage area 30. A prior art R Theta scanner, having a scanner head 201 and scanner base 230 is shown in FIG. 2. Again, the area to inspect 240 is larger than the coverage area 220. One and two axis prior art string encoders are shown in FIGS. 3 and 4, respectively. In FIG. 3, there is a single spring-loaded string 320 attached to an inspection head 310 and a scanner base 330. Again, the area to inspect 340 is larger than the coverage area. In FIG. 4, there are two spring-loaded strings 421 attached to an inspection head 410 and scanner bases 432. As in the three previous examples, the area to inspect 440 is larger than the device can cover in one positioning of the scanner base.
The inventors have developed a novel system for tracking and displaying the portions of a surface that have been scanned. The solution guarantees that the full surface will be covered with an adequate overlap and that indications are not missing. As the inventive system does not require a fixed reference point on the part under inspection nor any mechanical link between the scanning head and the part to be inspected, it is faster to deploy and does not limit operator agility.
DESCRIPTION
Description of the Drawings
FIG. 1 is a prior art diagram of an are under test by an XY inspection head;
FIG. 2 is a prior art diagram of an area under test by a testing device for use on cylinders;
FIG. 3 is a prior art block diagram of a one axis string encoder;
FIG. 4 is a prior art block diagram of a two axis string encoder;
FIG. 5 is a drawing of an exemplary scanner and an exemplary display; and
FIG. 6 is an exemplary system diagram.
DETAILED SPECIFICATION
As shown in FIG. 6, an inspection head 610, connected to an inspection computer 620 is provided with two position encoders 611, 612. Encoder 1 and 2 provide individual probe end position. Exemplary encoders can be of any kind, for example the known devised using a wheel, an image or time of flight. It is even possible to use dual axis (or more) encoders that give X and Y positions. As the probe is moved across a surface under test, the encoders provide position information that, among other things, is used to produce a display showing the area that has been traversed by the probe. A display is configured to “paint” the area under test with each subsequent area covered by the probe, so that the operator can ensure that the entire surface has been tested by observing the display to see that it is completely covered by the cumulative image produced by the scanner feedback.
To increase precision the system can also use more than two encoders. One possible combination is to use two pairs of two axis wheels (like an omni-wheel) or rolling spheres (like a mouse track ball) in a “X” pattern and have between 2 and 8 encoders positioned on the two axis wheels or rolling spheres.
In an exemplary embodiment, shown in FIGS. 5 and 6, a non-destructive testing (NDT) scanner 510, 610 is fitted with movement encoders 611, 612. In an embodiment, the user must indicate to the system the starting point and initial direction of the scanner relative to the area to inspect. Once the scanner is moving, the encoders provide individual probe end positions allowing the system to calculate probe new position and orientation. If more than two encoders are used, then an average can be calculated for greater precision. FIG. 5 shoes a single scan track 520 in an area to inspect 540. FIG. 6 shows the indication of the scan track on the data acquisition device 620. With many encoders it can also be possible to reject aberrant values. The calculations can take place within the scanner, within the acquisition device or in an intermediate device. Calculations can be performed using any type of calculation device such as and not limited to FGPA, processors, DSP, micro-controllers. The positions and orientations are correlated with the NDT information and plotted on the acquisition device 620 screen as shown in FIG. 6.
By having encoders on two sides of an inspection head, as shown in FIG. 6, it is possible to know the orientation of the head, which does not have to be kept in a rectilinear path, as shown in FIG. 5.
Patent Application
20170241956
