Process for contact-free determination of forces and/or torque acting on a hollow-cylindrical body as well as a measurement arrangement for implementing the process

1. Method for contactless determination of forces and/or moments acting on a hollow cylindrical body ( 12 ), comprising

by means of a light source ( 20 ; 38 ; 40 ), light radiation is produced within the hollow cylindrical body ( 12 );

measurement signals of the light radiation are recorded by means of an optoelectronic sensor ( 22 ; 34 );

the measurement signals recorded by the optoelectronic sensor ( 22 ; 34 ) are supplied to a signal processing unit ( 26 );

the signal processing unit ( 26 ) detects and outputs changes of the measurement signals relative to an initial state determined beforehand by calibration, corresponding to an initial undeformed state of the hollow cylindrical body ( 12 );

when a mechanical deformation of the hollow cylindrical body ( 12 ) is present, according to a calibration function or a calculation rule, the signal processing unit ( 26 ) outputs an output signal that describes the forces and/or moments that are causing the mechanical deformation of the hollow cylindrical body ( 12 ).

2. Method according to claim 1 , characterized in that determination of the forces and/or moments is done on a turning hollow cylindrical body ( 12 ).

3. Method according to claim 2 , wherein the relationship between the deformation of the hollow cylindrical body ( 12 ) and the forces and/or moments causing the deformation is determined by means of an experimentally determined calibration function or by means of an analytical or numerical calculation rule.

4. Method according to claim 1 , wherein the relationship between the deformation of the hollow cylindrical body ( 12 ) and the forces and/or moments causing the deformation is determined by means of an experimentally determined calibration function or by means of an analytical or numerical calculation rule.

5. Method according to claim 1 , wherein the measurement signals are measured by means of the signal processing unit ( 26 ) with digital image processing.

6. Measurement arrangement for implementing the method according to claim 1 , comprising

the optoelectronic sensor ( 22 ; 34 );

the light source ( 20 ; 38 ; 40 );

the signal processing unit ( 26 );

an energy source ( 28 ); and

means for signal and/or voltage supply ( 31 ) between the energy source ( 28 ), the signal processing unit ( 26 ), the light source ( 20 ; 38 ; 40 ) and the optoelectronic sensor ( 22 ; 34 ).

7. Measurement arrangement according to claim 6 , wherein the signal processing unit ( 26 ) has a digital image processing unit.

8. Measurement arrangement according to claim 7 , wherein the optoelectronic sensor is designed as a photodetector ( 22 ), and the light source is designed as a laser module ( 20 ) with an integrated laser diode, whereby the photodetector ( 22 ) is located on a first end ( 24 ) of the hollow cylindrical body ( 12 ) and the laser module ( 20 ) is located on an opposite end, each within the hollow cylindrical body ( 12 ), and a light beam emitted from the laser module is aligned directly to the photodetector ( 22 ).

9. Measurement arrangement according to claim 6 , wherein the optoelectronic sensor is designed as a photodetector ( 22 ), and the light source is designed as a laser module ( 20 ) with an integrated laser diode, whereby the photodetector ( 22 ) is located on a first end ( 24 ) of the hollow cylindrical body ( 12 ) and the laser module ( 20 ) is located on an opposite end, each within the hollow cylindrical body ( 12 ), and a light beam emitted from the laser module is aligned directly to the photodetector ( 22 ).

10. Measurement arrangement according to claim 9 , wherein the photodetector ( 22 ) and the laser module ( 20 ) are each located on a cover that closes the hollow cylindrical body ( 12 ).

11. Measurement arrangement according to claim 6 , wherein the optoelectronic sensor is designed as a photodetector ( 22 ) and the light source is designed as a laser module ( 20 ) and they are each located outside of the hollow cylindrical body ( 12 ), and wherein there is a mirror ( 30 ) on the inside on the first end ( 24 ) of the hollow cylindrical body, whereby the photodetector ( 22 ), the laser module ( 20 ) and the mirror ( 30 ) are arranged relative to one another such that a light beam emitted by the laser module ( 20 ) is incident on the photodetector ( 22 ) only after reflection on the mirror ( 30 ).

12. Measurement arrangement according to claim 11 , wherein in a region of the laser module ( 20 ), there is another reflector ( 32 ) via which a light beam emitted from the laser module ( 20 ) can be deflected onto the mirror ( 30 ).

13. Measurement arrangement according to claim 6 , wherein on one end ( 24 ) within the hollow cylindrical body ( 12 ), there is a pattern/grid ( 36 ) and the optoelectronic sensor is designed as a camera ( 34 ) with a CCD or CMOS sensor, whereby the light source ( 38 ) is located inside or outside and the camera ( 34 ) is located outside of the hollow cylindrical body ( 12 ).

14. Measurement arrangement according to claim 13 , wherein the light source ( 40 ) is located within the hollow cylindrical body ( 12 ) and the light source and the pattern/grid form a unit.

15. Measurement arrangement according to claim 14 , wherein the pattern/grid is made from a self-illuminating material.

16. Measurement arrangement according to claim 15 , wherein the pattern/grid is made from tritium.

17. Measurement arrangement according to claim 6 , wherein the optoelectronic sensor is designed as a photodetector ( 22 ) and the light source is designed as a laser module ( 20 ) with an integrated laser diode, whereby the photodetector ( 22 ) and the laser module ( 20 ) are located on a first end ( 24 ) of the hollow cylindrical body ( 12 ), on a cover ( 41 ) that closes the hollow cylindrical body ( 12 ), whereby the photodetector ( 22 ) and the laser module ( 20 ) are located within the hollow cylindrical body ( 12 ), and wherein a collimator ( 42 ) is located on an opposite end, within the hollow cylindrical body ( 12 ), whereby the collimator ( 42 ) is connected to the laser module ( 20 ) by means of a glass fiber ( 44 ).

18. Measurement arrangement according to claim 17 , wherein a collimator ( 42 ) is held in a sleeve ( 43 ) within the hollow cylindrical body ( 12 ) for alignment of the collimator ( 42 ).

19. Rotary wing aircraft, wherein the measurement arrangement according to claim 6 is used for determining a strut moment of a main rotor strut.