WO2006097423A1

WO2006097423A1 - Device for determining the position and/or orientation of a navigable object

Info

Publication number: WO2006097423A1
Application number: PCT/EP2006/060559
Authority: WO
Inventors: Dirk Diehl; Rainer Kuth; Johannes Reinschke; Rudolf Röckelein; Wolfgang Schmidt; Stefan Kirsch; Christian Schilling
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-03-17
Filing date: 2006-03-08
Publication date: 2006-09-21
Also published as: DE102006010730A1

Abstract

The invention relates to device for determining the position of a navigable object (12) that is present within a magnetic background field (Hex) of a predetermined frequency-dependent amplitude of its magnetic induction, said field being generated by coils (13i, 23j) of a background field coil system (3). At least a part of one of the coils (13i, 23j) of the background field coil system (3) is simultaneously used as the transmitting coil for generating a magnetic position measuring field (Hp) having a predetermined frequency at the location of the object (12), the amplitude of the position measuring field (Hp) at the location of the object (12) being greater than that of the background field (Hex) at the predetermined frequency. The inventive device also comprises a receiver (21) for receiving position signals (S1) generated by the object (12) depending on the position measuring field (Hp) and means for processing and evaluating the position signals (S1).

Description

description

Device for determining the position and / or orientation of a navigable object

The invention relates to a device for determining the position of a navigable object that is within a magnetic background field with predetermined at the location of Ob ^¬ jektes, frequency-dependent maximum amplitude of its magnetic induction, the background field of coils of a background coil system ^¬ called out and navigation of the object is provided. This includes the device

a system of transmitting coils for generating a position measuring field at the location of the object,

- a receiving device for receiving generated from the object in response to the position measurement field Po ^¬ sitionssignalen and - means for further processing and analysis of the position signals.

In principle, a determination of orientation should also be understood as meaning a position determination. A corresponding device is e.g. DE 101 42 253 Cl to remove.

In the field of medical technology, non-invasive or minimally invasive procedures are gaining in importance ^¬ tung. Such measures are standing here as a collective term for comparable for various medical projects such as di ^¬ agnosen (visual inspection, biopsies) or therapies (targeted drug delivery, mounting clips or stents). The measure is to be carried out on ^subjects such as humans or animals. Particularly desirable is the implementation of such measures inside the subject, especially in the interior of hollow organs such as the entire gastrointestinal tract. For carrying out such medical measures, special navigable objects such as capsules or capsule systems can be provided (cf., for example, EP 0 667 115 A, US Pat.

DE 101 42 253 C1). A corresponding overall system is also referred to as Endoroboter. In general, however, other bodies to be navigated, such as e.g. Catheter tips, for which, if necessary, a wire connection to the outside is possible conceivable.

For a magnetic, non-free navigation of a capsule, this th with magnetic material such as permanent magnets ^¬ appropriate magnetization direction or ferromagnetic parts or current-carrying coils which generally produce a magnetic moment to be fitted. By externally applied, suitably controllable magnetic fields Kräf ^¬ te and possibly torques can be exercised on the correspondingly designed object.

A corresponding endorobot system can be found in WO 03/028224 A2. The system includes a magnetic coil system for non-contact navigation of a video camera equipped with a video camera. In addition, a device for determining the position of the capsule should be provided. For this purpose, the system comprises special transmitter coils and a system of receiver coils arranged in the capillary. With these coils, the signals generated by the transmitting coils are detected and transmitted to the outside to a non-descript Emp ^¬ receiving device.

Also in the aforementioned DE 101 42 253 Cl a ent ^¬ speaking video capsule is described, which is equipped with a Stabmagne ^¬ th and video and other intervention devices. On the bar magnet to exert an external magnetic ^¬ coil system forces. It mentions a free-floating, so-called helicopter mode with control via a 6D mouse, a feedback of forces acting on the capsule forces via the mouse and a position feedback by a transponder. Details of the realization of the required The coil system and the operation of its individual coils are not explained in detail in the document.

/ A concrete plant to a non-contact movement and or fixing is a magnetic body in a working space by using a magnetic coil system Ge ^¬ subject of the non-prepublished German Patent Application 103 41 092.9. The magnetic fields to be applied externally by the magnetic coil system can be subdivided into a magnetic basic field for generating a torque on the magnetic body and a magnetic gradient field for magnetically generating translatory forces thereon. That is, the magnetic fields to be applied are not spatially homogeneous, but location-dependent. Has a predetermined force and a predetermined torque are generated according to the correct gradient magnetic field and the right may ^¬ genetic background field at the location of the magnetic body or whether ^¬ jektes. It is therefore necessary to know the current location and the angular position, ie the position and orientation or spatial orientation of the magnetic body. Also magnetic fields to be used for position and / or Orientierungsbe ^¬ atmospheric. Such fields are superimposed on the magnetic field formed by magnetic field and magnetic gradient field, hereinafter referred to as the background field magnetic field.

However, use of known electromagnetic field based position sensing systems is eliminated because of the interference with the force generating magnetic background field. In addition, existing systems generally operate with wire connections from the measurement site to the outside. For an application in a endorobot but preferably a wireless Ver ^¬ is aimed compound.

Furthermore, systems for position and angle measurement of objects such as catheter tips in the human body are known. These work according to the electromagnetic principle with static and relatively low frequency fields in the kilo hertz range. Fields are sent in different spatial directions via stationary transmitting coils. These are detected inductively via, on or in the object to be located object receiver coils and sent analog via wire connections to the outside. In this case, static and low-frequency fields are used in part with signals connected in chronological succession and at different frequencies of the transmitting coils in order to separate the signals of the individual transmitting coils from one another. Due to the frequency range used, a disturbance generated by the body tissue itself is practically negligible. However, if one goes to higher frequencies, for example in the MHz range, this is no longer the case.

The object of the present invention is therefore to at least reduce the above-mentioned problems in a device with the features mentioned above. In this case, an electromagnetic compatibility of position and / or orientation measuring systems operating according to the electromagnetic principle, in particular in the human body, with magnetic fields which are used for other purposes, such as imaging or navigation, should be provided. Should preferably also the possibility of a wireless transmitter ^¬ transmission of the sensor signals of the position measuring system from the body Inne- ren be given to the outside.

This object is achieved with the measures specified in claim 1. Accordingly, should the device for Positionsbe ^¬ humor of a navigable object, which is located within a background magnetic field of predetermined amplitude of its magnetic induction, which is of coils of a background-coil system caused, - a system of transmitter coils for generating a position measuring field at least one predetermined frequency at the location of the object with more than the amplitude of the magnetic induction of the background field at the predetermined frequency Fre ^¬ opposing magnetic induction, - a receiving device for receiving generated from the object in response to the position measurement field Posi ^¬ tion signals, and - including means for further processing and analysis of the position signals and be formed according to the invention in that at least one of the transmitting coil, at least part of a coil is at the same time of the background field-coil system.

The term "position determination" is understood here and below as meaning also a spatial orientation determination, that is, with the device according to the invention a position and / or an orientation determination should in principle be executed simultaneously or separately from one another.

In the inventive measures is based on the fact that usually magnetic background fields for magnetic navigation are relatively low frequency. At each frequency, the background field has a ^certain amplitude of magnetic induction or field strength. The value of the amplitude depends on the respective Fri ^¬ off frequency. The maximum value is generally assumed to be at a frequency below 1 kHz.

In contrast, systems must be in a position and / or orientation determination generally at much higher frequencies, typically about 10 kHz to about 100 kHz, ar ^¬ BEITEN. In any case, tables than the amplitude of the magnetic ^¬ induction must, however, be ensured that at the predetermined frequency or the predefined frequencies, the approximate determination of the systems to a position and / or Orientie ^¬ caused amplitude of the magnetic induction having a larger value of the background field , This makes it possible to use the transmission coils for the position detection system in the field-generating coils of the other purpose

Integrate magnetic coil system. For example, flow-generating flows can be used to exert forces and torque. elements are siege to the object a higher-frequency magnetic field Überla ^¬, which leads to the induction gleichfrequenter voltages and currents in sensor coils position of the object and thus can be used as a position signal. The signal strength can be set variably. Depending on the background field generator, considerably higher field strengths than with the previously used position measuring systems can be transmitted. The expenditure on equipment with respect to the required coils is reduced accordingly. Since the input device for position and / or orientation determination operating in a different frequency range than the magnetic Spulensys ^¬ system to the background field generation, an undesirable mutual influence can at least substantially be avoided ^¬ ver.

Advantageous embodiments of the device according to the invention will become apparent from the dependent claims. In this case, the embodiment of the device according to claim 1 with the features of one of the dependent claims or preferably also nen from several sub-claims can be combined. Accordingly, the device according to the invention may additionally have the following features:

• Thus, the position of the object signals may be transmitted to by means of a signal transmission unit that further signals transmission for over ^¬ is provided. Such further signals may be generated by a sensor or an actuator, wherein the sensor may in particular be a video or pH value or pressure sensor or the actuator in particular a biopsy forceps.

• The signal transmission unit may be a Funkübertra ^¬ be generating unit or wired.

The magnetic background field may be such as to provide, in particular, non-contact navigation of a magnetic object which is mechanically connected to the object Body act. Corresponding fields are applied to endorobot systems.

• The coils for generating the background magnetic field or parts of these coils do not need that completely

Form system of transmitting coils. Accordingly, the system of transmit coils may include additional coils adjacent to one, some or all of the coils of the background magnetic field coil system.

It is expedient to provide additional amplifiers for coupling in the signal of the transmitting coils.

• The signals of the transmitter coils are either superimposed on the magnetic background field at the same time or can be generated separately from it.

• advantageous to adapt the signals of the transmitter coil ^¬ takes place their strength and / or its frequency and / or frequency and / or pulse width modulation to the background field and / or other entity acting Magnetfel ^¬ the respect.

• In general, in the case of magnetic navigation of objects, the useful frequency of the maximum amplitude of the background magnetic field does not exceed 100 Hz, while the frequency of the position measuring field exceeds 1 kHz and extends to approximately 100 kHz. Such a separation of the frequencies is a good prerequisite for an undisturbed position and / or orientation determination.

• The object to be navigated is preferably a capsule of an endorobot system.

Further advantageous embodiments of the device according to the invention for position and / or orientation determination emerge from the subclaims not mentioned above. To further explain the invention is verwie ^¬ sen below to the removable from the drawing embodiment. The single FIGURE shows a schematic representation of a system for the non-invasive examination and / or treatment of a subject with an endorobot comprising an inventively designed device, in particular for a non-contact position and / or orientation determination of its endoscopy capsule.

In the endoscopy unit, generally designated 2, it is assumed that equipment known per se is used. Not shown or explained parts of the system are the general state of the art. The basic structure and the operation of the endoscopy system 2 is also described in DE 103 41 092Al. The system comprises a coil system 3 for generating a magnetic background field with a power supply 4 connected thereto and a control and regulation unit in order to be able to navigate a capsule without contact as an object 12. The capsule ver ^¬ adds in particular via a sensor such as a video, pH, or pressure sensor and / or an actuator such as a biopsy forceps. These parts communicate through the same signal ^¬ transmission unit with the outside world, via which the polyvinyl sitionsmesssignale be transmitted to the outside world. In the figure, a video unit used here is indicated 6 is ^¬.

To generate a basic magnetic field and a magnetic gradient field of the background field H _ex , the coil system 3 consists of a total of 14 individual coils. For reasons of clarity, only four individual coils are designated in greater detail by these coils. These are subdivided into six (i = 1 ... 6) cuboid arranged rectangular Helmholtz coils 13i and 13a and 13b, and in eight (j = 1 ... 8) in common ^¬ sam a cylinder jacket in a cuboid forming saddle coils 23j or 23a and 23b. Each of the saddle coils 23i sweeps be ^¬ züglich a central center longitudinal axis A of the coil system 3 an angular range of about 90 °; ie, four saddle coils form approximately a cylindrical shell shape.

The coil current flowing in each of the fourteen individual coils is generated by one of fourteen (k = 1... 14), each associated with a single coil power amplifiers 8k, of which in turn again only three amplifiers 8a to 8c are indicated in the figure. The fourteen power amplifiers 8k together form the power supply 4. All power amplifiers are controlled or regulated by the control and regulation unit 5 via a respective control line 9k.

A subject or patient 10 to be examined is to be introduced along the axis A into the coil system 3. It is placed in the coil system in such a way that an endoscopy capsule 12 swallowed by it comes to rest approximately in the middle of the coil system. There, the coil system has a so-called Ar ^¬ beitsvolumen, within which the capsule can be navigated without contact by means of the coil ^¬ system.

The endoscopy capsule 12 is based on known ^embodiments (cf.

DE 101 42 253 C1, EP 0 676 115 A1). It should have essentially three components, namely a magnetic element required for navigation, such as a permanent magnet or a body made of or with ferromagnetic material or a current-carrying coil, a position sensor with one or more sensor coils and a video component. Accordingly, the capsule carries in its interior at its front end a camera and Beleuchtungseinrich ^¬ tion not shown. Through a viewing window the area of the capsule is illuminated and can take an image of the capsule environment ^¬ the camera. The recorded image data are either immediately or preprocessed and, if necessary after intermediate storage by radio, transmitted as video signals S2 to a video receiver 14 outside the magnetic coil system 3 and displayed on a screen 15 of the video unit 6. To control the capsule movement in the coil system 3 or within the Subject 10 is an input device in the form of a 6D mouse 16, which is operated by an operator, not shown, for example, a doctor examining the patient, based on the image displayed on the screen 14.

The spatial position of the capsule endoscope 12 and the Orientie ^¬ tion of its longitudinal axis 17 is collected through an inventive device for position and / or orientation determination. Of this device, generally designated 20, in the figure essentially only one receiving unit 21 is indicated, which detects the position data or signals S1 emitted by the endoscopy capsule and transmits them to the control and regulation unit 5. If necessary, these signals can also be transmitted by wire.

For the position detection of the capsule endoscope 12, it requires an additional magnetic field H _p, acting on the or the Po ^¬ sitionssensorspulen the endoscopic capsule with one or sev- eral (different) frequencies. The frequency range for the corresponding field of this field signals _p, referred to as position measurement field H is substantially higher than the generally at most 100 Hz reaching Nutzfre ^¬ frequency range of the coil system 3 for generating the magnetic field H _ex see background. Preferably, the frequency of the position measuring field (H _p ) is between 1 kHz and 100 kHz. According to the invention, the transmission coils for the position detection are to be integrated into the field generators of the coil system used for the magnetic background field H _ex . In other words, currents are superimposed on the flow-generating currents for exerting forces and torques on the capsule 12 in order to generate a further, higher-frequency magnetic field H _p . This further magnetic field H _p leads to the induction of equal-frequency voltages and currents in the position sensor coils of the endoscopy capsule 12. These voltages and currents can thus be used as a position signal. The signal strength can be set variably. The higher frequency AC currents for generating the other magnetic field or position measuring field H _p, which in general ^¬ my in the range between 1 kHz and the lOOkHz-range, can be bought by additional amplifier makes available, inductively or capacitively to the flusserzeu- ing individual coils 13i and 23j of the coil system 3 angekop ^¬ pelt be. Instead, as indicated in the figure at the power amplifier 8c, a corresponding bandwidth of, for example, 20 kHz, the amplifier 8k assuming at the inputs of the transmitter signals to generate the additional magnetic field superimposed. The corresponding generator ^¬ unit is in the figure with 22, their individual generators or amplifiers are designated 24m (with m = l ... m). The additional generators 24m required for further individual coils have been omitted for the sake of clarity.

The resulting coil current in the frequency range of the position measurement is then measured and, via the then known magnetic field, serves as one of the input variables for calculating the position of the sensor coils of the endoscopy capsule 12.

The high-frequency signals of the sensor coils are then amplitude-modulated or frequency-modulated in the capsule and transmitted to the receiving unit 21 via radio frequency from the examination object to the outside as analog signals S1. Selbstver ^¬ understandable is a digitization of the high-frequency signals, pre-processing and a transmission entspre ^¬ accordingly processed signals to the receiving unit 21 possible.

It is optionally also possible to use the measuring ^¬ already sent signal or video signal S2 of the video part of the capsule for the transmission of the position signals.

For suppressing a disturbance of the transmitter field by external, uncorrelated magnetic field sources in the frequency range of

Measuring system can also be provided a phase-sensitive detection of Sig ^¬ signals to the receiver coils in the manner of a lock-in technique. Was related to in the subsequent embodiments according to the invention position / orientation determining means distinguishes between -. A sensor coil system which position magnetic fields at a sensor location, such as a capsule endoscope, receives sitionsmessung to Po ^¬, and

- A transmission coil system which generates magnetic fields for supplying the aforementioned sensor coil system. These two coil systems, together with a known computing unit for converting the sensor signals into positions, form a so-called position measuring system. Further, the coil system provided for generating a background magnetic field H _ex is generally referred to as - an external magnet system which fields for others

Purpose as for position measurement, in particular for positioning of catheter tips and / or for navigation magnetbestückter capsules generated.

In addition, there is often wireless transmission of a video or other measurement signal from the capsule to the outside.

The prerequisite for a functioning capability of a device according to the invention for position and / or orientation determination thus defined is that the frequency ranges in which the position measuring system and the external magnet system work can be separated from one another. As a rule, the external magnet system will operate at a lower frequency. Typically, the frequencies of the external magnet system are below 1 kHz, while those of the Positionsmesssys ^¬ tems are above this value, in particular about 10 kHz and up to about 100 kHz range. In this case, the electromagnetic compatibility of the position measuring system and the external magnet system can be disturbed by the following effects: a) External DC fields and / or AC fields with useful frequencies below 100 Hz lead to: d) excitation of oscillations of the transmitter coils by Lorentz forces, L ₁ ) Saturation of external parts in the position measuring system. b) Generation of eddy currents in conductive parts such as the external magnet system by the Sendespulen ^¬ system and associated distortions of the field generated by the transmission coil system. c) External AC fields in the frequency range of the transmitting coil ^¬ system, for example, shares in the field of external Magnetsys ^¬ tems in the frequency range of the transmitting coil system with ähn ^¬ Licher or higher amplitude.

In consideration of these aforementioned Störeffek ^¬ te can be the following countermeasures in detail Vorse hen ^¬:

To effect a,

The transmitting coil system is designed so that it can withstand the forces acting on it without that occur deformation or mechanical vibrations, the mood, the Positionsbe ^¬ or other system characteristics affect kön- nen. These requirements are usually caused by the con ^¬ the coil of the transmitting coil system constructive tion already fulfilled by be shed with plastic this example. Depending on the respective external magnetic field system ^¬ Kgs NEN advantageous, at least some or all Einzelspu- len of the external magnet system are simultaneously used as a transmission system. In a endorobot can Spulensys ^¬ system which serves for movement of the capsule, are used. Possibly. the coils for generating the external magnetic field in number and / or arrangement are not sufficient to serve alone as a transmission system for position determination. Selbstver ^¬ understandable further coil may then be mounted or integrated, which kon ^¬ constructive tion due withstand the respective force effects to completion of the transmission system. This is especially the case if only parts of the Mag-netspulen be used for the external magnetic field as coils of Sendesys ^¬ tems.

To effect a _xl ) On the one hand, transmission coils of a position measuring system can contain ferromagnetic cores, which are driven into saturation in the external magnet system, so that then the generated fields are changed and the position determination is impaired. On the other hand, ferromagnetic objects, as they are to be provided for an endoscopy capsule, can be wholly or partially driven into saturation at the location of the sensor coils or in their immediate vicinity, whereby the fields at the location of the sensor coil are changed and, in turn, the position determination becomes erroneous. For this reason one can at the transmitting coil system using coils of the external magnet system and possibly also required to ^¬ rate coils completely ferromagnetic material ver ^¬ do without. The field distortions of ferromagnetic objects in the vicinity of the sensor can then be determined by calibration measurements and / or field calculations and taken into account within the positioning algorithm. The effect of fields of the transmitting coil or of the external magnet system on cores in the sensor coils causes no saturation effects because of the high air gap through the body. Typically, the fields generated by a magnetic capsule navigation system at the capsule location are very small and in the mT range.

To effect b)

The transmitter coil system must be able to generate defined and reproducible field distributions in order to enable accurate position determination. The field distortions due to conductive objects, in which non-negligible eddy currents are induced due to their position and / or size, can be taken into account by calibration measurements and / or by field calculations. The eddy current bodies are to be regarded as part of the transmitting coil system. If such We ^¬ belstromkörper movable, their current position must be included in the algorithm for determining position. To effect cl

High-frequency fields generated by sources other than the transmitter coil system are also detected by the position sensor coil and must be separated from the useful signal. Various solutions are conceivable for this:

- If the sources of interference are broadband and of low spectral density, a narrowband filtering, in particular passively or by means of synchronous detection, may be sufficient. - Occur stronger interference at defined frequencies, the useful signal can be separated by selecting a suitable frequency of the transmitting coil system in combination with narrow-band filtering.

- When high field strengths at different frequencies are generated by the external magnet system, one is

Synchronization with the position detection system conceivable.

- In the simplest case, the external magnet system is not energized or energized for the duration of the position detection, so that then no interference fields are generated. If it is not possible to dispense with the current supply of the external magnet system, a constant energization can take place for the duration of the position measurement. In this case, no high-frequency interference fields are generated.

- Does such a constant current supply to the external Mag ^¬ Netsystems due to non-ideal power sources such Leis ^¬ processing amplifier or switching power supplies still to high-frequency interference fields, the Störfeldspektrum is constant. This can then be recorded using the

Sensors on the endoscopy capsule or additional Senso ^¬ Ren, the frequency of the transmission system can be so ^¬ sets that the interference frequencies are just avoided. - If a position detection without synchronization with the external magnetic field, such as for a Kapselnaviga ^¬ tion, done reliably, so may advantageously a frequency or amplitude modulation of the transmission signal be provided, where appropriate, the current Störsignal ^¬ spectrum is taken into account by the navigation magnetic field. It is also a very broadband transmission signal with short transmission pulses analogous to known Ultra Wide Band (UWB) method or in turn in the individual transmit signal pulses pulsed transmission signal with Pulsweitenmo ^¬ modulation taking into account the temporal correlation between transmitted and received for example by the sensor system in the capsule Signals possible.

In the above embodiment, since it was considered ^¬ by that the coil system for generating the magnetic background field, at least with some of its len Spu ^¬ at the same time as a system of transmitting coils for generating a magnetic field position measuring is sufficient. Selbstverständ ^¬ it is possible Lich, that the transmitting coil system comprises coils for the position measuring field still further (additional). Thus, the coil system for generating the magnetic background field of coils with optimized winding numbers for this purpose exist, with partial coils of it with reduced

Number of turns can optionally serve with auxiliary coils as a transmitting coil system. It may also be separate, for example, electrically insulated coils can be integrated as transmitter coils in the coil of the coil system for generating the magnetic background field and, if so, with the auxiliary coils Sen ^¬ despulensystem. Moreover, it is also conceivable that passive additional coils and / or other shaped conductive Kör ^¬ per passively by eddy currents influence the field distribution for the purpose of positioning and improve and as an integral part of the transmitting coil system for Generie ^¬ tion of a magnetic position measuring field considered ^¬ to.

With a device according to the invention, therefore, the position and / or orientation of an arbitrary object can be detected contactlessly in a working volume by detecting position / orientation magnet fields emitted by the transmitting coil system from the object and transmitting it to an object. are returned unit, which determines the position of the received signals by means of known devices for electronic processing and evaluation. Particularly in applications in medicine may be in the Obwalden ject a with a magnetic element or induction ^¬ coil-equipped probe such as a catheter or a flexible endoscope or a small capsule camera with lighting and transmitters act, the video images from inside the body, such as the Digestive tract or the lungs or other parts of the body. In addition, the object may also be part of a ferromagnetic foreign body such as a needle or a functional module in inaccessible areas, which is moved or removed by magnetic forces. In addition to the application in medicine as well as the use of a device according to the invention in other areas such as in contaminated rooms is possible. With associated magnetic probes other, in particular inaccessible accomodat ^¬ me can be, for example, inspected internally, said probes can of course be equipped with different or additional functional tionality.

Claims

claims

1. A device for determining the position of a navigable object (12), which is within a magnetic background field (H _ex ) with at the location of the object (12) predetermined, frequency-dependent amplitude of its magnetic induction, wherein the background field (H _ex ) of coils (13i, 23 j) of a background field coil system (3) caused and provided for navigation of the object (12), which means

- a system of transmitter coils for generating a magnetic position measuring field (H _p) at least one ^pre-¬ given frequency at the location of the object (12) to be higher than the amplitude value of the magnetic induction of the rear base field (H _ex) at the predetermined frequency ^¬ the magnetic Induction,

- A receiving device (21) for receiving from the object (12) in response to the position measuring field

(H _p ) generated position signals (Sl) and

- Means for further processing and evaluation of the position signals (Sl) contains, wherein at least one of the transmitting coils at the same time at least part of a coil (13i, 23j) of the background field coil system (3).

2. Device according to claim 1, characterized by a frequency of the position measuring field (H _p ) between 1 kHz and 100 kHz.

3. Device according to claim 1 or 2, characterized in that the position signals (Sl) of the object (12) are to be transmitted by means of a signal transmission unit which is provided for the transmission of further signals.

4. Device according to claim 3, characterized in that the object (12) contains a sensor or actuator whose signals are the further signals.

5. Device according to claim 3, characterized in that the object (12) has a video or pH or pressure sensor or a biopsy forceps as an actuator.

6. Device according to one of claims 3 to 5, character- ized in that the signal transmission unit is a radio ^¬ transmission unit.

7. Device according to one of claims 3 to 6, characterized in that the signal transmission unit is wired gebun- the.

8. Device according to one of the preceding claims, characterized in that the magnetic background field

(H _ex ) is provided for navigation of a magnetic body mechanically connected to the object (12).

9. Device according to one of the preceding claims, characterized in that the system of transmitting coils in addition to at least one of the coils (13i, 23 j) of the background magnetic field coil system (3) comprises additional coils.

10. Device according to one of the preceding claims, characterized in that parts of the coils (13i, 23j) of the background field coil system (3) are provided as transmitting coils.

11. Device according to one of the preceding claims, characterized in that additional amplifiers (22m) are provided for coupling the signal of the transmitting coils.

12. Device according to one of the preceding claims, characterized in that the signals of the transmitting coil the magnetic background field (H _ex ) are to be superimposed or to be generated by this temporally separated.

13. Device according to one of the preceding claims, character- ized in that the signals of the transmitting coil towards ^¬ their strength and / or their frequency and / or a frequency and / or pulse width modulation to the magnetic background field (H _ex ) and / or other entity acting Magnetfel adapted ^¬ of.

14. Device according to one of the preceding claims, characterized in that the useful frequency of the magnetic background field (H _ex ) is less than 100 Hz.

15. Device according to one of the preceding claims, characterized in that the object is a capsule (12) of an endo-robot system.