FR2786577A1 - Remote manipulation of moving part inside a magnetically permeable enclosure, for use in medical applications - Google Patents

Abstract

The moving part (M) responds to magnetic fields and is placed inside the enclosure. Magnetic coils (X,Y,Z) are placed outside the enclosure, perpendicular to each other. Detectors provide information on the position of the moving part inside the enclosure. This information is used to assist in controlling the moving part by adjustment of the magnetic field in each of the three axes.

Description

1 2786577

  The present invention relates to a device for handling mobiles arranged beforehand.

  near an enclosure permeable to magnetic fields.

  It relates more particularly to a device making it possible to control in position in the three directions of space, a body or a substance having electromagnetic properties, this body being able to cooperate at the level of various elements or tools in order to be able to manipulate them or to activate without disturbing the surrounding environment. More specifically, the invention is intended for medical, surgical, therapeutic applications

or diagnostic, minimally invasive.

  Many systems are known for performing remote manipulations. Most use a rigid or semi-rigid mechanical system with rods capable of driving tools (telemanipulator arm, abdominal, thoracic or urological microsurgery, cardiac catheterization probes, etc.). These systems are very efficient, but often remain inappropriate because they often have to reach inaccessible or risky areas due to the presence of neighboring organs which hinder access. In addition, these manipulations, even if carried out by experts, often require

  traumatic surgical procedures for the individual.

  The present invention therefore aims to overcome these drawbacks by proposing a device which can ensure the movement and positioning of a mobile in a volume, without having to penetrate the volume containing the mobile

to activate it.

  To this end, the device for moving at least one mobile near an enclosure permeable to magnetic fields, is characterized in that it comprises at least one mobile having electromagnetic properties, placed within a volume bathed by the magnetic field of electromagnets X1, X2, Y1, Y2, Z1, Z2 arranged on the periphery of the enclosure, for example Xl, X2, Y1, Y2, Z1, Z2 assembled in pairs according to a system of axes x, x '; y, y'; z, z ', said electromagnets Xl, X2, Y1, Y2, Z1,

2,278,677

  Z2 being associated with a plurality of sensors intended to supply information to a device for controlling and piloting the electromagnets making it possible to control the direction on the one hand, and the position of said mobile in space on the other hand. Other features and advantages of this

  invention will emerge from the description given below, in

  reference to the accompanying drawings which illustrate an embodiment thereof devoid of any limiting character. In the figures: - Figure 1 is a schematic view of the various components of the device; - Figure 2 is a view of a particular application of the device, the latter being associated for example with a surgical probe; - Figure 3 is a schematic view of the device associated with a means for creating an external rotating field; - Figure 4 is a schematic view of the device associated with a means for creating an internal rotating field; FIG. 5 is a schematic view which illustrates a mode of coupling between a DC generator and

  an alternating current generator;

  - Figure 6 is a schematic view which illustrates the embodiment of a device for circulating the current alternating in two using a semiconductor device; - Figure 7 shows a probe which includes a coil and a control circuit; - Figure 8 shows a Ariane wireless mobile, the switching control being carried out using codes

sent using the H.F.

  According to a preferred embodiment of the device which is the subject of the invention, it consists in placing in an enclosure representing the volume in which a mobile M having electromagnetic properties can move in the three directions of space:

3,278,677

  - 3 pairs of electromagnets, oriented along 3 axes, substantially orthogonal or pseudo-orthogonal; - a plurality of sensors for measuring the intensity, the rate of change of the magnetic fields acting on the three axes previously defined; - a control system, in particular of the computer or automaton type making it possible to control and control the position, the speed of movement, the acceleration, both in a Cartesian and polar coordinate system, the mobile placed in the defined space between the different coils of the electromagnets; - a system for controlling the current of the coils, from the signals coming from the various sensors

  giving the coordinates of the mobile in space.

  Reference will be made to FIG. 1 which schematically illustrates the arrangement of the various components of the invention. The electromagnets X1 and X2 are placed on either side of the axis x, x 'and generate a magnetic field of variable intensity and gradient and oriented along this axis. The electromagnets Y1 and Y2 are placed on either side of the axis y, y 'and generate a magnetic field of variable intensity and gradient and oriented according to this

axis.

  The electromagnets Z1 and Z2 (Z2 not being shown so as not to make the figure heavier) are placed on either side of the axis z, z 'and generate a magnetic field of variable intensity and gradient and oriented according to this

axis.

  These electromagnets consist of a single coil whose plane of the turns is perpendicular to the axis considered, or each electromagnet is a combination of three coils arranged perpendicularly in space; this latter configuration offers the possibility of having all possible variants for controlling the mobile in space, in particular for ensuring the

transverse movements of the mobile.

4 2786577

  Also shown in this figure is the mobile M that we want to move, which is made in whole or in part from a material with electromagnetic properties, for example a magnet, and is oriented along any axis relative to the 3D mark, it is also positioned in the field of action of

  different solenoid coils.

  In the example presented below, this mobile is

formed by a magnet.

  Under the action of the intensity of a magnetic field which is in fact the result of the different intensities of the fields produced by the various electromagnets, this resulting magnetic field is oriented in a particular direction of space which, when is not confused with the axis passing through the poles of the magnet (constituted by the mobile), creates a gap which causes a return torque of the magnetic axis of the mobile towards the axis of the resulting field coming from coils Xl, X2, Y1, Y2, Zl, Z2, we can thus change the direction of the mobile

considered.

  By acting on the gradient of the magnetic fields resulting from the two opposite electromagnets on the same axis, a force is oriented along the axis of these two electromagnets which allows the movement of the mobile according to

a privileged direction.

  By combining this mode of action on all the electromagnets X1, X2, Y1, Y2, Z1, Z2, it is possible to

move the mobile in space.

  By associating the two phenomena (modification of the intensity of the magnetic fields produced by the electromagnets and modification of the gradient applied between two electromagnets), it clearly appears that one can position the mobile at any place in the space confined simply by the volume between the various

electromagnets.

  If the axis of the magnet coincides with that of the mobile, the 6-coil device can only ensure that

axial movement of the mobile.

2786577

  The transverse displacement can be obtained by two alternatives: either using the 18 coils, each electromagnet being composed of 3 coils arranged perpendicularly in space, which can generate field gradients in all axes, or using of 6 coils, each electromagnet then being composed of a single coil, choosing a preferred direction of the axis of the mobile with respect to the axis of the field emitted by the mobile, by electromechanical or electromagnetic means (for example, 3 coils arranged

perpendicularly in space).

  The measurement of the position of the mobile or the magnet in the volume can be carried out in several ways: - the first method consists in detecting the components of the magnetic field emitted by the mobile playing the role of magnet. The magnetic field generated by the magnet is measured using a plurality of sensors such as in particular magnetoresistive elements placed along the 3 axes. According to an advantageous characteristic of the invention,

  the sensors are placed in the center of each of the 6 coils.

  This avoids placing anything other than the

  mobile within the volume defined by the coils.

  To be able to make measurements of the field emitted by the mobile, it is preferable that the coils Xl, X2, Y1, Y2, Z1, Z2 provide a chopped field, that is to say, a continuous mean field which is interrupted periodically in order to perform said measurements. It is possible to provide a chopped field to said coils, either with switches which cyclically interrupt the flow of current through all of the coils, or by superimposing on direct current an alternating current whose peak is equal to the average value of direct current. We then obtain at each period, a brief moment when the currents cancel each other out.

  and therefore o the field, produced by each coil, disappears.

  In addition, the field values are sampled at this time and stored, in analog or

6 2786577

  digital, to provide the control system with

stable value.

  In addition, the piloting of the sampling device is preferably controlled by a plurality of current detection sensors placed on each of the coils Xl, X2,

Y1, Y2, Z1, Z2.

  According to another characteristic, it is provided that the sampling frequency must be all the higher if one wishes to slave the position of the magnet quickly: the sampling period defines the delay of the measurement which is mathematically linked to the bandwidth of the servo device. In practice, a frequency of the order of 1 to 10 kHz is chosen in order to

  reduce this response time to very low values.

  We also plan to take into account the parasitic values which can affect the measurement of the real field coming from the mobile: thus for example, we measure the terrestrial magnetic field in order to be able to subtract it from the measured values to obtain the most precise value.

possible.

  In the same vein, we also take into account the background noise which can be notably the current supply under 50/60 Hz, or noises

from engines.

  - The second method consists in detecting a high frequency field using an element associated with the (mobile) magnet. The magnet is then associated with an LC circuit, i.e.

passive, either active.

  In the case of a passive LC circuit, a pulsed magnetic field is added to the average magnetic field so as to create a current in the circuit. This resonates on its natural frequency and re-emits a high frequency magnetic field. It is also possible to permanently excite at a frequency superimposed on the DC field and measure harmonics created by the LC circuit associated with

  one or more non-linear elements.

7 2786577

  In the case of an active LC circuit, an integrated circuit emits for example brief bursts of high frequency. The

  circuit is supplied either autonomously (e.g.

  batteries), either with a wire, or by rectifying the voltage obtained at the terminals of an inductance (self) excited by an alternating or pulsed field superimposed on the average field, this field will preferably be oriented perpendicular to

this inductance.

  We then have on each of the 3 axes of the coils

  to recover the signal emitted by the LC circuit.

  - A third method consists in measuring phase differences introduced by the presence of the circuit between a transmitting coil at a frequency slightly higher or lower than the resonance frequency of the LC circuit and

a take-up reel.

  - A fourth method consists in measuring the change in the values of the inductances formed by the coils which are modulated by the presence of the magnetic body. - A fifth method consists in placing at least two electrodes on two opposite faces of the magnet and in supplying them with alternating current. The electric field created (preferably at high frequency) propagates in the medium and can be measured by simple electrodes placed on the periphery. This method is

  particularly applicable to the exploration of the human body.

  - And finally a last method to determine the position of the mobile, consists in using any variation of an optical, electrical, radiological, acoustic signal ... by coupling it to a transmitter, a

detector and analyzer.

  From the values measured on these elements, a command and control system which provides the exact position in the space of the magnet (mobile): position and axis in the coordinate system considered. The linearity of the set is obtained by correction equations integrated into the calculation. These equations can be obtained mathematically, or simply by

8 2786577

  learning, by memorizing the measurements found on a large number of points and by interpolating this data to

  find the intermediate values.

  The control system receives commands from a plurality of sensors giving the values of the 6 references as a function of time. This can be a kind of "Joystick" or three-dimensional mouse moved manually (possibly with force feedback from the servo system) or simply a memory having

  previously stored a given sequence of these references.

  The role of the computer is to control the average current of the 6 electromagnets so as to bring the position and orientation of the magnet to the set values at any time. Like any servo system, the computer calculates the error in each position and sends the error currents to the 6 electromagnets. The calculation can be optimized by adding a calculation of speed, acceleration, integration, derivatives, in order to increase the speed of response without risking producing oscillations. The magnet thus oriented is capable of pushing with greater force the higher the field gradient. By using superconducting coils, the fields of the order of a Tesla produce very strong forces.

  important on a very small magnet.

  By associating the device described above with a tool (pliers, scalpel, screwdriver, pencil ...) which is either passive or controlled from the outside by any transmission system (radio frequency, optics, modulation of magnetic fields present, or simply a wire with a micromechanical interface), the device is suitable for

all kinds of applications.

  Thus, one can move a mobile in the human body (fitting a probe, fitting a prosthesis, depositing a therapeutic substance ...). For this, the magnet is equipped with a probe holder. It guides the probe to the point (s) sought by the operator. When

9 2786577

  the probe must remain in place definitively, the device applies a force which allows the blocking of the probe, then loosens the probe holder in order to be able to come out: it is indeed essential not to leave in place in the body of the magnets which would make impossible all

similar manipulation in the future.

  The probe positioned by the device which is the subject of the invention is of a diameter which can be very reduced (given that no rigidity is necessary to transmit the mechanical forces, unlike traditional probes, outside of a rotational movement) and is thus brought to places that are difficult to access by conventional means in

as short a time as possible.

  The magnet cannot be left in the body so as not to disturb future interventions. The clamp holding the probe must therefore be able to release it at the time chosen by the operator. In the case of an assembly used only once (the magnet being mounted on the probe in the factory), all that is required is a mechanism of the fissile type which is triggered under the effect of an electrical command (at using 2 flexible wires which allow the magnet to be easily brought back at the same time). Otherwise, various means making it possible to remote control the clamp: micro-motor, electromagnet, hydraulic system, bimetallic strip, sliding ring can be envisaged. You can also cut, excite, heat or cool, sew, modify the shape of an organ in the human body. With a retractable scalpel, it is possible to imagine performing microsurgery in

  perfectly inaccessible places.

  However, according to the interventions envisaged, the magnet thus connected to the tool moves with it a "breadcrumb" which makes it possible to supply with suction liquid (rinsing of the operating area), with treating or therapeutic liquid, or to supply power (use of high frequency coils or resistors to locally heat some areas and destroy them), even if

2786577

  is still possible to recover energy from the

  oscillating field in which the device is bathed.

  We can also associate with this magnet a micro-

  camera to follow what is happening in situ.

  The field of application of such a device is immense: elimination of tumors, aneurysms, intravascular clots or atheroma plaques, repair of damaged tissues, stimulation test in neurology, cardiology, tunneling, examination of the entire digestive tract ...., and this by avoiding as much as possible any major invasive act that can generate lesions and discomfort in

the patient.

  According to another application, the device which is the subject of the invention can be used to feel a wall in order to determine its shape; indeed, when the mobile abuts against this wall, the force to move it increases suddenly. This increase is detected by the device which deduces the position of the wall in space. By moving the mobile step by step along this wall (by sliding or by hopping) and by carrying out multiple measurements, the device can therefore construct a three-dimensional image of this wall. The measurement of the intensity of the force can make it possible to measure incidentally the flexibility of the wall (difference between various tissues) or the pressure of a liquid in a vessel. More particularly, in the case of an application of the device to the exploration of a tissue, such as in particular the displacement of the device within an artery or any other conduit, it is advantageous to provide in addition to the system of piloting and control of the coils and therefore of the mobile, software that can both

  work in manual or automated mode.

  Indeed, using software, it is easy to considerably optimize the examination. This software can react very quickly to various stresses coming from the contact of the mobile with the walls and move 11i 2786577 "intelligently" and very quickly the mobile inside

of the duct.

  We can also, in addition to this software, use a database containing the model of the elements contained in the space in which the magnet moves and thus respond more quickly to displacement

  of the magnet from one point to another of the conduit.

  Alternatively, the mobile used can be made of a magnetic material without remanent magnetization (soft iron for example) or be constituted by a coil or a superconductive toroid. This technique, which is difficult to use today because it requires very low temperatures, can be applied in certain environments, or in the future when materials are superconductive at room temperature. The torus behaves like a magnet whose field is proportional to the flux which crosses it. he

  allows very high forces to be obtained.

  The mobile can use a coil instead of the magnet, the latter emitting a magnetic field if

  it is correctly supplied with electric current.

  Unlike the magnet, it makes it possible to obtain a variable field: - it can be interrupted: the coil then has practically no more interaction with the medium. This gives the possibility of leaving the mobile in place without disadvantage with regard to future examinations (other interventions or by Nuclear Magnetic Resonance). he

  suffices then to cause a definitive interruption.

  This is obtained either by disconnecting the coil (in the case where there is a breadcrumb), or by blowing a micro fuse (by overvoltage for example), or

by electronic switch.

  Alternatively, it is possible to temporarily interrupt it in order to either reuse the mobile left in place for a certain time, or switch between

  several mobiles bathing in the same volume.

  In the latter case, the switching command can advantageously be carried out either from a device

12 2786577

  external controlled by the control system (case of breadcrumb), either using a circuit connected to a receiving coil to the HF (high frequency) magnetic field, equipped with at least one decoder allowing to specify a code specific to each mobile. The H.F.field is supplied by external coils, possibly the same as those which generate the power field. The supply system of these coils contains a modulation system (for example phase modulation) which allows the

  high frequency transmission of these codes.

  It also contains a device for controlling the axis of the H.F. field, which allows it to be kept always

  in the axis of the take-up reel.

  To complete the device, it is advantageous to propose an adjustment of the tuning of the HF generator: Indeed, when several mobiles are in the same field, it is necessary to easily discriminate the HF frequencies emitted by them. By adding after the code a value responsible for modulating the frequency of the generator, it is possible to assign to each mobile a

very precise frequency.

  According to a first embodiment, an alternating current can be used which is often easier to maintain than a direct current, it is quite possible to have an alternating field produced by the coil, provided that the external coils produce

also an alternating field in phase.

  According to a second embodiment, the variable field is obtained by coupling the coil to the H.F. generator or to the H. F. position detector, and possibly to

the take-up reel.

  The mobile contains up to 3 coils; one to create the restoring force, one to send a H.F. positioning signal and possibly one to receive the

  power of the H.F. field and supply the assembly.

  A classic electronic assembly makes it possible to combine the different functions with a single coil in order

to save a precious place.

13 2786577

  In the case where only the restoring force and the H.F. emission are required, it suffices to couple a direct current generator with an alternating current generator.

(cf. figure 5).

  There is shown in Figures 5, 6, 7, 8, receiving coil by B.R., high frequency transmitting coil by

  B.E.H.F., and transmitting coil by B.E.

  To associate the HF receiver, which eliminates the "breadcrumb", it is sufficient, for example, to circulate the current alternating in two using a semiconductor device (diode by example) (cf.

figure 6).

  The supply voltage V + is obtained by rectifying the "free" alternation (positive in FIG. 6). This voltage feeds the H.F. oscillator which injects its signal on the coil. A small inductance ("self") prevents short-circuiting of the H.F. current with the switching components. An even simpler solution is to take advantage of the sudden change in current that occurs with each cycle

  to emit a harmonic (principle of passive LC).

  In all cases, it is possible to neutralize the conduction of the semiconductor device and the transmitter.

  (or resonator) H.F. by an electronic switch.

  However, the proper functioning of the assembly only seems possible if the transmission frequency is higher than the reception frequency. For example 10MHz

for 1MHz.

  The alternative which consists in placing the position detector within the mobile can be achieved by

fairly simple means.

  The coil can be used as a sensor for 6 HF fields of different frequencies: 2 for the X axis (fXl and fX2) 2 for the Y axis (fY1 and fY2) and 2 others for the Z axis (fZ1 and fZ2). In practice, each axis contains 2 coils placed outside the volume, each emitting at its own frequency (alternatively, we can use 3

14 2786577

  frequencies: 1 per axis, and a phase difference between the 2

coils of the same axis).

  The signal obtained on the mobile coil allows

  find the exact position and direction of it

  here, after measuring the amplitude of the 6 frequencies (or of the 3 frequencies and of the phases): - The distance in X for example is proportional to the ratio between the amplitude of the frequency (fXl / fX2), likewise the distance in Y is proportional to the ratio between the amplitude of the frequency (fY1 / fY2), as well as the distance

  in Z which is a function of the frequency ratio (fZl / fZ2).

  - The direction of the probe is calculated by the ratio between the 3 amplitude means (fXl + fX2) / 2, (fYl + fY2) / 2 and (fZl + fZ2) / 2, means modulated by the angle made the

  coil with each axis, except for linearity errors.

  A big advantage of this device is the complete independence of each mobile for position measurement: it is no longer necessary to worry about discriminating the frequencies emitted by each mobile and each mobile.

becomes relatively simple.

  In the case of a probe to be guided to a given site, it suffices to fix a small coil at the end of the probe and to connect its two wires to the outside (cf. figure 7). In this figure, the general control starts the generator of direct current (or alternating current), when it wishes to apply a force on the probe, after having stabilized the general field. The coil is then traversed by direct (alternating) current and receives the forces or torques necessary to maintain or change its position. Piloting then stops the generator, and multiplexes its operation with that of other mobiles

(if any). The coil permanently receives the 6 (or 3) frequencies fXl, fX2, fY1, fY2,

  fZ1, fZ2 and the demodulator provides the

  position calculator the amplitudes of each.

2786577

  The unit is disconnected after use and becomes

  then perfectly passive vis-à-vis external fields.

  This position measurement system can also be used for a Ariane wireless mobile, by transmitting the content of the 6 (or 3) frequencies (and the 3 phases) using the HF emission of the mobile which is not used while

local transmission.

  According to another embodiment of the device which is the subject of the invention, making it possible to control the angular position of the magnet around its north-south axis, this consists in associating with the magnet a means capable of generating a continuous rotation of the magnet within the mobile to be piloted (gyroscopic movement), or capable of generating a bi field

or stable sorting.

  In a first embodiment, the means consists in coupling to the magnet a motor which rotates the magnet at a perfectly known speed. The coils Xl, X2, Y1, Y2, Z1, Z2 do not provide a field of fixed vectors, but a field rotating at the same angular speed as

the magnet (see Figure 3).

  In this configuration, the magnet is positioned in a stable position when its north-south axis is oriented

  along the same axis as the rotating field.

  The major interest of this rotating field is to be able

  create a couple on the mobile according to its three axes.

  - Y axis: when the rotating field accelerates, it rotates faster than the magnet and the mobile is subjected to a torque which makes it rotate along this axis (or rather according to

  the motor axis, if the latter corresponds to the Y axis).

  - X and Z axes: as long as the magnetic field rotates in the plane perpendicular to the axis, it does not cause torque. As soon as the plane changes inclination, it causes a restoring torque in a plane perpendicular to the axis of the motor (if the latter is oriented along Y, the torque of

recall takes place in plane X, Z).

  It is therefore possible with this method to control the position of the mobile in all directions of space.

16 2786577

  In parallel with the use of a rotating field, the piloting and control system must take into account the respect of the field gradients which manage the movement of the mobile in the directions X, Y, Z, by modulating the instantaneous values. Another solution for controlling the angular position of the magnet around its north-south axis consists in making an internal electromagnet within the mobile (cf.

figure 4).

  By alternately exciting at least 2 coils, allowing either to provide a regular rotating field (sine of e on one, and cosine of e on the other, in order to obtain a control similar to that of the external rotating field), either a stable field bi along 2 perpendicular axes, or even a field of any axis in a plane (using 2 coils) or in space (at

using 3 coils).

  In this case, the coils X1X2, YlY2, Z1Z2 switch so as to alternately produce two vectors perpendicular to the same frequency as the electromagnet of the

  mobile, with a modular duty cycle.

  The mobile having 2 coils (or 3) perpendicular to control its movements can be advantageously associated with a controlled switching system

by the general system.

  In the case where there is a breadcrumb, the control of the switching of each coil indeed allows: - to grant a more or less long time to each coil, in order to optimize the forces available to provide either a general movement of the mobile, that is a torque around its axis. It may be preferable to grant 80% to the general movement and 20% to the rotation for the basic movements, whereas to screw an element, it will be necessary to apply 80% to the rotation and 20% to the general movement; - to multiplex several mobiles by activating one, then the other, to regulate the current passing in each coil

  in order to define a resulting field axis.

17 2786577

  If the mobile does not have a breadcrumb trail, the switching command must be carried out using codes

sent using the H.F.

  This system is advantageously shown in the figure

8.

  The system can use, for example, 6 codes: 2 to put "ON / OFF" the current in the first coil, 2 to put "ON / OFF" the current in the second coil, and

  2 to set the H.F. generator to "ON / OFF"

  As described above for single coil devices, it is technically possible to combine several functions (reception, H.F. generator),

  with the 2 main transmitting coils.

  It is also possible to have only these 2 coils to control a mobile equipped with breadcrumb, either having a HF generator for positioning, or recovering and demodulating the 6 frequencies emitted in the 3 axes. The two methods of controlling the angular position of the magnet and therefore of the mobile are particularly intended, on the one hand for medical applications such as in particular when a scalpel is used at the end of the mobile (any parasitic rotation thereof can lead to significant damage to the tissue) or when, for example, the mobile is used to screw a probe into a tissue, on the other hand to common applications such as for example, a fish in an aquarium, a pencil

  writing on a sheet of paper ...

  It remains to be understood that the present invention is not limited to the exemplary embodiments described and shown above, but that it encompasses all variants thereof. Thus, the device makes it possible, for example, to move an isolated element dressed in decorative elements, representing for example a fish in an aquarium or a component associated with passive elements: net for catching a mobile, point for piercing a membrane, scalpel for cut a tumor, or a device associated with remote-controlled active elements either by

18 2786577

  mechanical using a flexible connection by wire, either optically or more generally electromagnetically. In the latter case, the transmission energy can be taken from the oscillating electromagnetic field responsible for holding the tool in position.

19 2786577

Claims (12)

  1 - Device for moving at least one mobile near an enclosure permeable to magnetic fields, characterized in that it comprises at least one mobile (M) having electromagnetic properties, placed within a volume bathed by the magnetic field of electromagnets arranged on the periphery of the enclosure, for example (Xl, X2, Y1, Y2, Z1, Z2) assembled in pairs according to a system of axes (x, x '; y, y'; z, z '), said electromagnets (Xl, X2, Y1, Y2, Zl, Z2) being associated with a plurality of sensors intended to supply information to a device for controlling and controlling the electromagnets making it possible to control the direction of a share, and the   position of said mobile in space on the other hand.   2 - Device according to claim 1, characterized in that each electromagnet (Xl, X2, Y1, Y2, Zl, Z2) is consisting of at least one coil.   3 - Device according to one of claims 1 or 2,   characterized in that each of the electromagnets (X1, X2, Yl, Y2, Z1, Z2) comprises at least one sensor making it possible to detect the cancellation of the current passing through the conductors of the coils and therefore the cancellation of the magnetic field, in order to ensure at this instant the sampling, by the command and control device, of the value of the   magnetic field from the mobile (M).   4 - Device according to any one of   previous claims, characterized in that the mobile   (M) forming a magnet is associated with a passive LC circuit.   5 - Device according to any one of   Claims 1 to 3, characterized in that the mobile (M)   forming a magnet is associated with an active LC circuit.   6 - Device according to any one of   previous claims, characterized in that the mobile   (M) is powered by a high frequency field which is supplied by induction, the axis of this magnetic field being controlled by the position of the mobile and in a direction   perpendicular to the induction coil. 2786577   7 - Device according to any one of   previous claims, characterized in that the mobile   (M) is associated with a tool, which is either passive or controlled from the outside by any transmission system, which makes it possible to move the assembly within a volume. 8 - Device according to any one of   previous claims, characterized in that the mobile   (M) is made of a magnetic material without remanent magnetization.   9 - Device according to any one of   Claims 1 to 7, characterized in that the mobile (M)   has at least one coil made of material conductor or superconductor.   - Device according to any one of   Claims 1 to 9, characterized in that it includes   means for temporarily or permanently neutralizing said coil, and possibly additionally said LC circuit.   11 - Device according to any one of   previous claims, characterized in that the mobile   (M) is coupled to a motor which rotates the mobile (M) at a perfectly known speed, the electromagnets (Xl, X2, Y1, Y2, Z1, Z2) providing a vector field rotating at the same angular speed as the mobile,   thus allowing to control its angular position.   12 - Device according to any one of   Claims 1 to 7, characterized in that the mobile (M)   is associated with at least two coils of perpendicular or pseudo-perpendicular axes and with a device which excites one and / or the other of these coils, making it possible to create either a regular rotating field, or a stable field bi along two axes perpendicular, or a resulting field   elementary fields emitted by each coil.   13 - Tool cooperating with a device according to one   any of the preceding claims, characterized in   what it allows to cut, excite, heat or cool,   sew, modify, visualize, palpate the shape of an organ. 21 2786577   14 - Probe holder cooperating with a device according to   any one of claims 1 to 12, characterized in   what it allows to move a mobile in the human body, such as in particular the installation of a prosthesis or the deposit of a therapeutic substance.