APPARATUS AND METHOD FOR POSITION DETERMINATION

• US 20100281983A1
• Filed: 05/06/2010
• Published: 11/11/2010
• Est. Priority Date: 05/11/2009
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Dirauf, Franz, Muench, Michael, Faustmann, Hendrik, Lindner, Gerhard
• Granted Patent: US 8,833,170 B2
• Time in Patent Office: Days
• US Class Current: 73/627
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G01S 15/08 Systems for measuring distance only indirect measurement G01S15/46
• CPC Class Codes: G21K 1/046 varying the contour of the field, e.g. multileaf collimators

Abstract

An apparatus for determining a distance includes a converter element that generates n acoustic surface wave, a surface that feeds over at least part of the acoustic surface wave to a surface having a reflection point, and a processor that determines a distance between the apparatus and the reflection point from the propagation time of the acoustic surface wave. The converter element registers the acoustic surface wave reflected at the reflection point.

Claims

1. An apparatus for determining a distance, the apparatus comprising:

a converter element operable to generate an acoustic surface wave;

a surface operable to feed at least part of the acoustic surface wave to a reflection point; and

a processor configured to determine a distance between the apparatus and the reflection point from the propagation time of the acoustic surface wave,

wherein the converter element is operable to register the acoustic surface wave reflected at the reflection point.

2. The apparatus as claimed in claim 1, wherein the position of the reflection point relative to an end of a surface having the reflection point is known, and

wherein the processor is configured to calculate the position of the end from the distance between the apparatus and the reflection point and the position of the reflection point relative to the end.

3. The apparatus as claimed in claim 1, wherein the converter element is an electromechanical converter element.

4. The apparatus as claimed in claim 3, wherein the electromechanical converter element is a piezoelectric interdigital converter.

5. The apparatus as claimed in claim 1, wherein the converter element is operable to generate a volume sound wave and convert the volume sound wave to the acoustic surface wave using mode conversion.

6. The apparatus as claimed in claim 5, wherein the converter element further comprises a piezoelectric thickness mode transducer for generating the volume sound wave.

7. The apparatus as claimed in claim 1, wherein the surface of the apparatus is configured for coupling to the surface having the reflection point for the purposes of feeding over the acoustic surface wave.

8. The apparatus as claimed in claim 7, wherein the surface of the apparatus is provided with a sliding element.

9. The apparatus as claimed in claim 8, wherein the sliding element is grease.

10. The apparatus as claimed in claim 1, wherein the processor is configured to identify a reflection pattern of the acoustic surface wave reflected at a plurality of reflection points that are close to one another in a direction defined by a path of the reflected acoustic surface wave in relation to the extension of the surface having the reflection points.

11. The apparatus as claimed in claim 1, wherein the surface of the apparatus is operable to feed the acoustic surface wave to a surface of an object, which is configured to move relative to the apparatus.

12. The apparatus as claimed in claim 11, wherein the surface of the apparatus is operable to feed the acoustic surface wave to a plurality of objects.

13. The apparatus as claimed in claim 12, further comprising a plurality of wave splitters disposed one behind another,

wherein the acoustic surface wave generated in the converter element passes along a path through the plurality of wave splitters, and

wherein the plurality of wave splitters each divert part of the acoustic surface wave to be fed to one of the plurality of objects and each allow another part of the acoustic surface wave to pass through.

14. The apparatus as claimed in claim 1, wherein the converter element is operable to transmit an additional acoustic surface wave along a path within the apparatus, and

wherein the processor is configured to:

determine the propagation time of the additional acoustic surface wave for the transmission; and

determine the distance from the apparatus to the reflection point using the propagation time of the additional acoustic surface wave, the length of the path within the apparatus, and the propagation time of the acoustic surface wave.

15. The apparatus as claimed in claim 1, wherein the converter element is operable to register acoustic surface waves reflected at two different reflection points, and

wherein the processor is configured to:

determine the propagation speed of the acoustic surface waves from the distances between the apparatus and the reflection points and the two propagation times of the reflected acoustic surface waves; and

use the determined propagation speed to determine the distance to another reflection point from the propagation time of another acoustic surface wave reflected at the another reflection point.

16. The apparatus as claimed in claim 1, wherein the reflection point comprises a notch.

17. The apparatus as claimed in claim 1, wherein the acoustic surface wave is a Rayleigh wave, a wave in the transition range between Rayleigh waves and Lamb waves, or a Lamb wave.

18. The apparatus as claimed in claim 13, wherein the processor is configured to determine the position of leaves of a multileaf collimator.

19. A method for determining a distance, the method comprising:

generating an acoustic surface wave using an apparatus;

feeding at least part of the acoustic surface wave to a surface having a reflection point;

registering the at least part of the acoustic surface wave reflected at the reflection point using the apparatus; and

determining a distance between the apparatus and the reflection point from the propagation time of the at least part of the acoustic surface wave.

20. The method as claimed in claim 19, further comprising:

calculating the position of an end of the surface from the distance between the apparatus and the reflection point and the location of the reflection point relative to the end of the surface,

wherein the location of the reflection point relative to the end of the surface is known.

21. The method as claimed in claim 19, wherein generating the acoustic surface wave comprises:

generating a volume sound wave using the apparatus; and

converting the volume sound wave to the acoustic surface wave using mode conversion.

22. The method as claimed in claim 19, further comprising:

identifying a reflection pattern by reflecting the acoustic surface wave at a plurality of reflection points that are close to one another in a direction defined by a path of the reflected surface wave in relation to the extension of the surface.

23. The method as claimed in claim 19, wherein the acoustic surface wave is fed over to a number of objects.

24. The method as claimed in claim 23, wherein the apparatus comprises a plurality of wave splitters disposed one behind another, and the acoustic surface wave generated in the apparatus passes along a path through the plurality of wave splitters, and

wherein the plurality of wave splitters each divert part of the acoustic surface wave to be fed over to an object and allow another part of the acoustic surface wave to pass through.

25. The method as claimed in claim 19, further comprising:

transmitting an additional acoustic surface wave along a path within the apparatus;

determining the propagation time of the additional surface wave for the transmission; and

determining the distance between the apparatus and the reflection point using the propagation time of the additional surface wave, the length of the path within the apparatus, and the propagation time of the acoustic surface wave.

26. The method as claimed in claim 19, further comprising:

registering two acoustic surface waves reflected at two different reflection points of the surface;

determining the propagation speed of the acoustic surface waves from the distances between the apparatus and the reflection points and the propagation times of the two reflected acoustic surface waves; and

determining the distance to another reflection point using the determined propagation speed and the propagation time of another surface wave reflected at the another reflection point.