Method for positioning and/or communicating with a pig

1. A method for positioning and/or communicating with a pig located in a hollow and elongate object, the method comprising the steps of:

positioning at least one inner transducer of the pig on an inner side of a wall of the object;

positioning at least one outer transducer on an outer side of the wall of the object;

generating at least one ultrasound signal in the wall; and

initiating, via the at least one inner transducer and the at least one outer transducer, a communication between the pig and a remote device external to the hollow and elongate object.

2. The method according to claim 1 , wherein at least two outer transducers are arranged on an outer wall of the object spaced apart from one another in a longitudinal direction of the object, and

wherein an ultrasound signal is generated in the wall,

wherein, by means of an evaluation and/or communication device, at least one of:

a relative position and/or spacing of the inner transducer with respect to the at least two outer transducers is/are derived from at least one travel time difference of the ultrasound signal and

a second communication is initiated via the at least one inner transducer and at least two outer transducers.

3. The method according to claim 1 , wherein the ultrasound signal, an additional ultrasound signal and/or a low-frequency electromagnetic signal is/are introduced from outside into the wall, said signal is received by the inner transducer, evaluated by the pig, and, on the basis of which, the pig transitions into a slow travel or a stop.

4. The method according to claim 1 , wherein, for communicating/for transmitting information, the frequency and/or the phase of the ultrasound signal or multiple additional ultrasound signals between the at least one outer transducer and the at least one inner transducer is/are varied.

5. The method according to claim 1 , wherein the transmission of information occurs as a function of the amplitude and/or the travel time difference.

6. The method according to claim 1 , wherein, based on an amplitude of the ultrasound signal, a change thereof, a maximum thereof and/or a deviation therefrom, a positioning signal is generated for the pig and/or for a travelling unit comprising at least one outer transducer and which can be moved along on the object.

7. The method according to claim 1 , wherein, on the basis of the travel time difference, a minimal and/or a no longer measurable travel time difference, a positioning signal is generated for the pig or a travelling unit comprising at least one outer transducer and which can be moved along on the object.

8. The method according to claim 6 , wherein the pig actuates an active drive means or a passive drive means on the basis of the positioning signal.

9. The method according to claim 1 , wherein the pig is guided by means of one or more positioning signals to a desired position where the wall is examined, cleaned, maintained and/or repaired.

10. The method according to claim 9 , wherein the examination, cleaning, maintenance and/or repair is/are regulated and/or controlled on the basis of information received by the inner transducer.

11. A system for carrying out a method according to claim 1 , the system comprising:

a pig arranged in a hollow and elongate object, the pig having at least one inner transducer arranged on the inner side of the object;

at least one outer transducer arranged on an outer side of the wall of the object, wherein the system generates at least one ultrasound signal in the wall;

an evaluation and/or communication system for at least one of:

evaluating the amplitude and

determining a spacing A and/or a relative position of the transducer.

12. The system according to claim 11 , wherein the transducers are electromagnetic ultrasound transducers (EMUS transducers) or as piezoelectric transducers.

13. The system according to claim 11 , wherein the transducers are EMUS transducers, and wherein the coils have a meandering design.

14. The system according to claim 11 , wherein the pig comprises at least one passive or active drive means.

15. The system according to claim 11 , wherein the system comprises a travelling unit which can be moved outside on the pipeline and which includes the outer transducer.

16. The method according to claim 1 , wherein, on the basis of the travel time difference, a minimal and/or a no longer measurable travel time difference, a positioning signal is generated for the pig or a travelling unit comprising at least one outer transducer and which can be moved along on the object; and

wherein the pig actuates an active drive means or a passive drive means on the basis of the positioning signal.

17. The method according to claim 1 , wherein the remote device external to the hollow and elongate object is a remotely operated vehicle.

18. The method according to claim 1 , wherein the communication includes data used for steering the pig.

19. The method according to claim 1 , further comprising deriving, via an evaluation and/or communication device, from an amplitude of the ultrasound signal, a relative position and/or a spacing between the at least one inner transducer and the at least one outer transducer.