EP1969410A1

EP1969410A1 - Device for fixing a first equipment item to a second equipment item, with active micropositioning

Info

Publication number: EP1969410A1
Application number: EP06847226A
Authority: EP
Inventors: Jean Dupuis; Laurent Blanchard
Original assignee: Thales SA
Current assignee: Thales SA
Priority date: 2006-01-03
Filing date: 2006-12-29
Publication date: 2008-09-17
Also published as: RU2418310C2; CN101421656A; WO2007077385A1; FR2895727B1; FR2895727A1; CN101421656B; RU2008131944A; US7902725B2; US20090174287A1

Abstract

A device (D), dedicated to fixing a first equipment item (E1) relative to a second equipment item (E2), comprises: i) a structure comprising a rigid central body (CC) extended by two substantially identical terminal bodies (CT1, CT2) each comprising a striction defining a flexible intermediate part (PD1, PD2) that is symmetric with respect to an element of symmetry, extended by a rigid internal part (PI1, PI2) that is symmetric with respect to the element of symmetry and secured to one of the ends of the central body (CC), and a rigid external part (PE1, PE2) that is symmetric with respect to an element of symmetry, spaced away from the internal part and intended to be secured to the first (E1) or second (E2) item of equipment; ii) at least two piezoelectric transducers (T11-T22) housed in empty spaces defined between the internal and external parts of the two terminal bodies (CT1, CT2) and each tasked with converting either an axial dimensional modification into a measurement current representative of the amplitude of the modification or a control current into a corresponding axial dimensional modification; and iii) control means (MC) tasked with determining at least one axial dimensional modification for at least one of the transducers so as to place the first equipment item (E1) in a chosen position relative to the second equipment item (E2).

Description

DEVICE FOR FIXING A FIRST EQUIPMENT ON A SECOND EQUIPMENT WITH ACTIVE MICRO POSITIONING

The invention relates to devices for allowing the attachment of a first equipment on or with respect to a second equipment, with a high accuracy or very high.

In certain fields, such as in the space field, some equipment is subjected to thermal and / or mechanical stresses which affect their stability of form and pose (the set of six parameters x, y, z, θx, θy, θz describing the relative position and attitude of two solids). They must then be subjected to stress relaxation and / or micro-repositioning. This is for example the case of the primary mirrors of telescopes, or of certain instruments of spatial observation, or of gradiometers.

When such equipment is secured to other equipment, by means of a fixing device (or connecting member), its installation and shape stabilities may also be disturbed by the thermal and / or mechanical stresses that this other equipment and / or its fastening device. This is what the skilled person calls the interface deformations.

In order to limit these disturbances, which induce deformations and / or displacements and / or rotations which notably prevent the initially fixed stability performances being maintained, passive fastening devices are generally used which have flexibilities chosen in certain directions and made of materials stable in temperature (such as carbon / resin composites).

These fixing devices may also comprise iso-static type support means, for example those which provide a three-point support by a passive fastening device such as those used for the mirrors (in particular described in the FR 97 patent documents). 13439 and FR 94 10710), an A-shaped support (or "A-frame") or a support in X shape (or "X-frame"). But these iso-static supports can generate residual stresses, due in particular to a sizing of the flexibilities to the launch loads.

It is also possible to provide passive thermal control devices, for example of MLI ("multi layer insulation") type, and / or active, such as for example heaters or heat pipes.

It is also possible to eliminate the mechanical integration constraints at the nominal operating temperature by performing precise pre-setting of the equipment. All these means implemented to limit the disruption suffered by the equipment prove to be expensive because of their complexity of mechanical manufacturing and / or the integration procedures that they require.

The invention therefore aims to improve the situation.

It proposes for this purpose a device intended to allow the attachment of a first equipment with respect to a second equipment, and comprising:

a structure comprising a rigid central body and two substantially identical end bodies, extending two opposite ends of the central body, and each comprising a constriction defining a flexible intermediate portion symmetrical with respect to a symmetry element (plane or axis of symmetry), presenting a first extension with respect to this element of symmetry, located in a central and prolonged position i) by a rigid internal part symmetrical with respect to the symmetry element, having a second extension with respect to the element of symmetry greater than the first and secured to one end of the central body, and ii) by a rigid outer portion symmetrical with respect to the symmetry element, having a third radial extension greater than the first, spaced from the inner portion and intended to be secured to the first or second equipment,

at least two piezoelectric transducers respectively housed in the free spaces defined between the inner and outer portions of the two end bodies and each being responsible for converting either an axial dimensional change into a measurement current representative of the amplitude said modification, a control current into a corresponding axial dimensional change, and

- Control means for determining at least one axial dimensional change for at least one of the transducers to place the first equipment in a selected position relative to the second equipment.

The device according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular:

its control means can be responsible for determining an axial dimensional change for each transducer in order to place the first equipment in a chosen position relative to the second equipment;

its control means can be loaded, when they receive a measurement current coming from a transducer of one of the terminal bodies, induced by a first disorientation of its external part with respect to its internal part, to determine the corresponding axial dimensional change and generating a control current to the transducer of the other terminal body so that it converts it into an axial dimensional change to induce a second disorientation of the outer portion of its terminal body with respect to its internal part, opposed to the first disorientation;

each free space of a terminal body can accommodate at least first and second piezoelectric transducers intended to operate in an antagonistic manner. In this case, the control means can be loaded, when they receive a measurement current from the first transducer of one of the terminal bodies, induced by a first disorientation of its outer part relative to its inner part, of determining the first corresponding axial dimensional change and generating i) a first control current to the second transducer of the same terminal body so that it converts it into a second axial dimensional change of opposite sign to the first axial dimensional change and same amplitude, ii) a second control current to the transducer of the other terminal body so that it converts it into a third axial dimensional change to induce a second disorientation of the outer portion of its terminal body with respect to its inner portion, opposite to the first disorientation, and iii) a third control current to the second transducer of the other terminal body so that it converts it into a fourth axial dimensional change of opposite sign to the third axial dimensional change of the same magnitude; each free space of a terminal body can accommodate three piezoelectric transducers placed at 120 ° from each other;

the control means can be loaded, when they receive at least one measurement current coming from at least one of the transducers of one of the terminal bodies, induced by a first disorientation of its external part with respect to its internal part, to determine each corresponding axial dimensional change and to generate i) a control current to each transducer, the same terminal body, which has not transmitted a measurement current, so that it converts it into a axial dimensional change, and ii) control currents for the three transducers of the other terminal body to convert them into axial dimensional changes to induce a second disorientation of the outer portion of its terminal body with respect to its internal part, opposed to the first disorientation; at least one of the inner and outer portions of each terminal body may be a platform of chosen shape, and the intermediate portion of each terminal body may have a diabolo-like shape; its transducers may be made of a piezoelectric material chosen from piezoelectric single crystals and piezoelectric ceramics;

the transducers may consist of at least one stack of at least one layer of the piezoelectric material; it may comprise at least one sensor responsible for delivering signals representative of at least one physical quantity. In this case, its control means are responsible for determining the axial dimensional changes as a function of the signals delivered by each sensor; its control means can be optionally activated and deactivated at selected times;

- Its control means can be arranged to operate in position control mode.

The invention also proposes an equipment provided with a fixing device of the type of that presented above.

The invention is particularly well suited, although not exclusively, to the space domain, to the generation of scanning movement (s) on equipment, and to dimensional measurements (interferometry) involved in the very fine positioning of equipment. Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings, in which:

FIGS. 1A and 1B illustrate, in schematic front views, a first exemplary embodiment of a fixing device according to the invention, of the "active flexible blade" type, respectively in the inactive phase and in the active phase,

FIGS. 2A and 2B illustrate, in schematic front views, a second exemplary embodiment of a fixing device according to the invention, also of the "active flexible blade" type, respectively in the inactive phase and in the active phase,

- Figure 3 illustrates in a schematic perspective view a third embodiment of a fixing device according to the invention, in the inactive phase.

The attached drawings may not only serve to complete the invention, but also contribute to its definition, if any.

The object of the invention is to enable active attachment of a first equipment on a second equipment.

In the following, we consider as a non-limiting example that the first equipment is a primary mirror of an observation instrument and the second equipment is this observation instrument, which is embedded on a satellite fulfilling a mission space observation of the Earth or a part of the universe, from space.

But the invention is not limited to these types of equipment. It concerns indeed any group of at least two equipment, space or not, intended to be secured to one another by means of a fixing device. It also relates to situations in which two devices must be aligned or micro-positioned quasi-statically relative to each other.

Referring firstly to FIGS. 1A and 1B, a first exemplary embodiment of a fixing device D according to the invention, of the "active flexible blade" or "active IPN beam" type, designed to secure the one to the other of the first E1 and second E2 equipment. When the device D is an active flexible blade, it has a very small extension in the direction perpendicular to the plane of the page (shown in Figure 1A by the axes XX and YY '). When the device D is an active IPN beam species, it has a relatively large extension in the direction perpendicular to the plane of the page (in this case, Figures 1 and 2 show cross-sectional views).

According to the invention, the fixing device D comprises at least one (fixing) structure, consisting of a central body CC and two end bodies CT1 and CT2 (or CTi, with i = 1 and 2), at least two piezoelectric transducers Tij, and an MC control module.

The central body CC is rigid type. It is here in the general form of a rectangular parallelepiped presenting a symmetry-type symmetry element (perpendicular to the plane of the page and materialized by the axis XX) and two opposite ends perpendicular to the plane of symmetry. But other forms can be envisaged. This is particularly the case in Figure 3 where the central body CC has a generally cylindrical shape circular whose axis XX constitutes the axis of symmetry.

The first CT1 and second CT2 terminal bodies are substantially identical. They respectively extend the two opposite ends of the central body CC. Here is meant by "extend one end" is the fact of being secured to the end, or being part of the same room as the central body CC.

Each terminal body CTi comprises a constriction, that is to say a narrowing, which defines an intermediate portion PDi flexible whose two ends are respectively extended by a rigid inner portion P1 and a rigid outer portion PEi. This necking is intended to flex (in the plane of the page) under the forces generated by the transducers (or actuators) Tij. It can be rounded or frank (that is, of constant width).

The intermediate portion PDi, flexible, is located in a central position of the structure, that is to say in the area through which the plane of symmetry (materialized by the axis XX). Moreover, it is preferably of symmetrical shape with respect to the plane of symmetry. In addition, it has a (first) extension in the direction YY ', perpendicular to the plane of symmetry (and therefore to the axis XX), and on either side of this plane of symmetry.

The rigid inner portion P 1 is integral with one of the two opposite ends of the central body CC. For example, it has a symmetrical shape with respect to the plane of symmetry. For example, it is in the form of a beam attached at its center to the intermediate portion PDi and the central body CC. This beam has a (second) extension on either side of the plane of symmetry (along the direction YY ') which is significantly greater than that of the central body CC.

The rigid outer portion PEi is intended to be secured to the first

E1 or second E2 equipment. In the examples illustrated in all the figures, the rigid outer portion PE1 of the first terminal body CT1 is secured to the first equipment E1, while the rigid outer portion PE2 of the second terminal body CT2 is secured to the second equipment E2.

Each rigid outer portion PEi has for example a shape symmetrical with respect to the plane of symmetry. For example, she introduces herself also in the form of a beam attached at its center to the intermediate portion PDi and one of the equipment. This beam has a (third) extension on either side of the plane of symmetry (along the direction YY ') which is significantly greater than that of the central body CC, and substantially equal to that of the rigid inner portion P11.

Unlike the rigid inner portion P1 which preferably has beveled sides on one of its faces (on the side of the central body CC) to enhance the rigidity of the structure, the rigid outer portion PEi is preferably of rectangular section. The second and third extensions of the inner fold and outer parts

PEi depend on the capabilities of the transducers (or actuators) Tij in terms of effort. Indeed, the more the actuator is placed far from the axis XX, the angular deflection is large with equal actuation capacity (in length). An actuator is thus moved away from the center of rotation in order to reduce actuation forces as it is placed near the center of rotation to reduce its stroke.

Due to the necking, a free space Si is defined between the inner and outer portions P1 PEi of each terminal body CTi, of course outside the area occupied by the intermediate part PDi. In the example illustrated in FIGS. 1A and 1B, the non-circular shapes of the inner portions P1 and the outer portion P1 result in a subdivision of the free space Si in two subspaces defining two housings, of substantially identical dimensions (at rest), on both sides of the intermediate part PDi.

In the example illustrated in FIGS. 1A and 1B, the device D comprises only two piezoelectric transducers Tij (T11 and T21, here j = 1). A first piezoelectric transducer T11 is housed in one of the two housings defined by the free space S1 of the first terminal body CT1, and a second piezoelectric transducer T21 is housed in one of the two housings defined by the free space S2 of the second terminal body CT2. In the example illustrated in FIGS. 1A and 1B, the first T11 and second T21 piezoelectric transducers are both placed in housings which are situated on the same side of the structure (with respect to the plane of symmetry). But this is not obligatory.

Each piezoelectric transducer Tij is secured to the internal portions P1 and external PEi of its terminal body CTi, at a chosen location of its free space Si. Moreover, each piezoelectric transducer Tij can perform two types of conversion. Either it converts the axial dimensional change (in the plane of the page and thus in a direction substantially parallel to the axis XX), which it is subject to due to a mechanical and / or thermal stress experienced by the end body CTi of which it is a part, in a measurement current representative of the amplitude of this modification, or it converts a control current from the control module MC into a corresponding axial dimensional change.

Here "axial dimensional change" is understood to mean an increase in dimension in a direction substantially parallel to the axis XX (associated with a positive sign amplitude), or a decrease in dimension in a direction substantially parallel to the axis XX ( associated with a negative sign amplitude).

For example, and as illustrated in all the figures, the transducers Tij are in the form of identical pads and equal in height to the distance between the inner portions P1 and external PEi of their terminal body CTi. These pads Tij may for example be parallelepipedal shape (as shown in Figures 1 and 2) or cylindrical circular section (as shown in Figure 3).

Each transducer Tij is for example made of a piezoelectric material such as piezoelectric single crystals. It could also be realized with piezoelectric ceramics. In general, any type of piezoelectric material can be used as long as it makes it possible to generate a measurement current large enough to be analyzable by the control module MC and / or to be the subject of a dimensional modification. axial direction adapted to the application, in response to a control current from the control module MC.

Piezoelectric single crystals are particularly interesting because they have a high elongation capacity, typically 2% (which is about ten times more than the elongation offered by piezoelectric ceramics).

Each transducer Tij may optionally consist of a stack of at least one layer of piezoelectric material and a layer of insulating material.

The control module MC is coupled to the transducers Tij by electrical conductors (for example cables) CE. It is generally responsible for determining at least one axial dimensional change for at least one of the transducers Tij of the device D, in order to place the first device E1 in a selected position with respect to the second device E2.

More specifically, the control module MC can be arranged in different ways to give the device D one or more functions. For example, the control module MC can determine only the dimensional change (axial along XX) of each transducer Tij so as to give the device D a micro-positioning function. In this case, it only transmits to the transducers Tij control currents that they must convert to axial dimensional changes in order to place the first equipment E1 in a selected precise position relative to the second equipment E2.

To facilitate the micro-positioning function, the device may comprise one or more physical size sensors, delivering signals representative of said physical quantities for the control module MC. This sensor (s) can (for example) perform a laser metrology and / or a determination of stress (s) to relax. In this case, the control module MC determines the control currents which are intended for the different transducers Tij according to instructions and the signals supplied by the sensor (s). Note that the device D can be used for the sole purpose of relaxing one or more constraints, when equipped with strain gauge (s). The control module MC may also be responsible for compensating at least partially the effect of a stress on at least one of its terminal bodies CTi. More precisely, when a terminal body CTi, for example CT2 (as illustrated in FIG. 1B), undergoes a constraint, this results in a first disorientation (inclination materialized by the arrow R1) of its external part PE2 with respect to its internal part PI2 because of the flexibility of the intermediate portion PD2 connecting them. This disorientation (R1) causes a first axial dimensional change, of a first amplitude, of the transducer T21 (materialized by the arrows F1). In the example illustrated in FIG. 1B, the first axial dimensional change is a decrease in thickness (but this could be the opposite). At the same time, the distance separating the inner PI2 and outer PE2 parts on the opposite side to the transducer T21 increases by a value equal to the first amplitude, as shown by the arrows F2. In response to this first axial axial reduction (decrease), the transducer T21 generates a measuring current representative of the first amplitude (and its sign). When the control module MC receives this measurement current (via the conductor CE), it determines the corresponding axial dimensional change and generates a control current for the transducer T11 of the first terminal body CT1. When the transducer T11 receives this control current, it converts it into a second axial dimensional modification making it possible to induce a second disorientation of the external part PE1 of its terminal body CT1 with respect to its internal part PU (represented by the arrow R2) . This second disorientation (R2) is opposed to the first disorientation (R1) in order to compensate for it. The second axial dimensional change is here an increase in thickness, of amplitude substantially equal to the first amplitude, but of opposite sign (materialized by the arrows F3). This second axial dimensional change (F3) at the same time causes a decrease in the distance separating the internal PU and external parts PE 1 from the first terminal body CT1 on the opposite side to the transducer T11, by a value substantially equal to the first amplitude, as materialized by the arrows F4.

Note that to provide this control function of the compensation of the effect of a constraint, the control module MC may possibly operate in servo mode (given constraint). It can also operate in servo mode with given axial dimensional modification.

Note also that the device D can both provide a function of micro-positioning and stress compensation (s).

Referring now to Figures 2A and 2B to describe a second embodiment of a fixing device D according to the invention. This is a variant of the first example described above with reference to FIGS. 1A and 1B. This second example differs from the first in that each terminal body CTi comprises two transducers Ti 1 and Ti 2, operating in an antagonistic manner. , not just one. This arrangement is indeed intended to overcome a disadvantage of the first embodiment related to the presence of a single transducer Tij in each terminal body CTi, and imposing that each piezoelectric transducer Tij is prestressed.

In this second embodiment, the control module MC controls the micro-positioning and / or the compensation of stress (s) via the four transducers Tij (T11, T12, T21 and T22).

For example, and as illustrated in FIG. 2B, when the control module MC operates in stress compensation (s), it receives a measurement current coming from one of the transducers Tij, for example the first one.

T1i, of one of the terminal bodies CTi, for example CT2, induced by a first disorientation (R1) of its outer part PE2 with respect to its internal part PI2.

It then determines the first axial dimensional change that corresponds to this measurement current, and then generates three control currents. In the example illustrated in Figure 2B, the first axial dimensional change is a decrease in thickness (but this could be the opposite), shown by the arrows F1.

The first control current is for the second transducer T22 of the second terminal body CT2. It is determined so that the second transducer T22 converts it into a second axial dimensional modification of opposite sign to the first axial dimensional modification of the same amplitude. This second axial dimensional change is here an increase in thickness, materialized by the arrows F2.

The second control current is for the first transducer T11 of the first terminal body CT1. It is determined so that the first transducer T11 converts it into a third axial dimensional modification intended to induce a second disorientation (R2) of the external part PE1 of its terminal body CT1 with respect to its internal part PU, opposite to the first disorientation . This third axial dimensional change is here an increase in thickness, materialized by the arrows F3.

The third control current is for the second transducer T12 of the first terminal body CT1. It is determined so that the second transducer T12 converts it into a fourth axial dimensional change of opposite sign to the third axial dimensional change and of the same amplitude. This fourth axial dimensional change is here a decrease in thickness, materialized by the arrows F4.

When the control module MC controls the micro-positioning, it determines measuring currents for the four transducers Tij, so that they operate within the same terminal body CTi antagonistically. The two embodiments described above only offer one or two degrees of freedom (translation in the direction YY 'and optionally a rotation). But, it is possible to envisage other embodiments offering more than two degrees of freedom, for example three or four. Such (third) exemplary embodiment is illustrated in FIG.

In this third exemplary embodiment, each terminal body CTi comprises inside its free space Si three piezoelectric transducers Tij G = 1 to 3) placed at 120 ° to each other with respect to the axis XX. The device is here symmetrical with respect to a symmetry-type symmetry element consisting of the axis XX.

As illustrated, the rigid inner portion P1 and / or the rigid outer portion PEi of each terminal body CT1 may for example be in the form of platforms, possibly of generally circular cylindrical shape. Moreover, the flexible intermediate portion PDi of each terminal body CTi may for example be in the form of a diabolo. This type of shape is indeed well adapted to rotations (or inclinations) in all directions.

The terminal bodies CTi are here symmetrical with respect to the axis of symmetry XX.

The central body CC is here of circular cylindrical shape, for example. It is here symmetrical with respect to the axis of symmetry XX.

The modes of operation offered by this third exemplary embodiment are identical to those described above with reference to FIGS. 1 and 2. The only difference lies in the fact that the possibilities of micropositioning are more numerous and that a greater number of Compensation can be made because of the presence of a triplet of transducers Tij in each terminal body CTi.

For example, when the MC control module controls the micro-positioning, it determines measuring currents for the six transducers

Tij, so that they operate in a combined triplet way within the same terminal body CTi. In fact, for a triplet of transducers Tij, two control currents make it possible to fix the first disorientation at a terminal body CTi, while the third control current serves to position the third transducer in an antagonistic manner with respect to the combination of the two others.

When the control module MC operates in constraint compensation (s), it receives at least one measurement current coming from at least one of the three transducers Tij of one of the terminal bodies CTi, induced by a first disorientation of its external part PEi with respect to its internal part Pli. It then determines each axial dimensional change corresponding to each measurement current received. Then, it generates, on the one hand, a current of control for each transducer, of the same terminal body CTi, which has not transmitted a measurement current, so that it converts it into a selected axial dimensional change, and secondly control currents to the three transducers of the other terminal body CTi 'so that they convert them into axial dimensional modifications making it possible to induce a second disorientation of the external part PEi' of their terminal body CTi 'with respect to its internal part P11', opposite the first disorientation.

It is important to note that whatever its embodiment, the control module MC may possibly be activated and deactivated at selected times. For example, the fixing device D, according to the invention, is blocked during launching and then activated once the satellite in which it is embarked has reached orbit at the location provided for its mission.

The device can for example be activated by embedded software during the observation phases of the mission. The invention offers a number of advantages, among which:

the device D can be miniaturized so as to be adapted to the load of the first equipment to be secured to the second equipment, so that its mass and its bulk remain low,

the device D making it possible to reduce the interface constraints in orbit, the equipment of high dimensional stability can therefore be designed and dimensioned less robustly, which leads to a reduction in mass,

the device D comprising flexible mechanical components, elastically deformed, it does not involve any friction or rolling which may accelerate its aging, impair its reliability or generate particulate pollution,

- The setting ranges offered by the device D allow simplified integration procedures.

The invention is not limited to the embodiments of fixing device and equipment described above, only by way of example, but it encompasses all the variants that may be considered by those skilled in the art in the context of the invention. of the claims below.

Thus, in the foregoing, an application of the invention has been presented the fine positioning of one equipment compared to another. However, the invention also relates to the alignment or the quasi-static micro-positioning of one equipment with respect to another.

Claims

1. Device for fixing a first device (E1) with respect to a second device (E2), characterized in that it comprises i) a structure comprising a rigid central body (CC) and two end bodies (CTi) substantially identical, extending two opposite ends of said central body (CC), and each comprising a constriction defining a flexible intermediate portion (PDi) symmetrical with respect to an element of symmetry, having a first extension relative to said symmetrical element, located in a position central and extended by a rigid inner portion (P1) symmetrical with respect to said symmetry element, having a second extension relative to said element of symmetry greater than the first and integral with one of said ends of the central body (CC), and a rigid outer part (PEi) symmetrical with respect to said symmetry element, having a third extension with respect to said element of symmetry symmetry greater than the first, spaced from said inner portion (P1) and intended to be secured to said first (E1) or second (E2) equipment, ii) at least two piezoelectric transducers (Tij) respectively housed in free spaces (Si) defined between the inner (P1) and outer (PEi) portions of the two end bodies (CTi) and each arranged to convert either an axial dimensional change to a measurement current representative of the amplitude of said change, or a control current in a corresponding axial dimensional change, and iii) control means (MC) arranged to determine at least one axial dimensional change for at least one of said transducers (Tij) so as to place said first equipment (E1) in a chosen position relative to said second equipment (E2).

2. Device according to claim 1, characterized in that said control means (MC) are arranged to determine an axial dimensional change for each transducer (Tij) so as to place said first equipment (E1) in a selected position with respect to said second equipment (E2).

3. Device according to claim 1, characterized in that said control means (MC) are arranged, when receiving a measurement current from a transducer (Tij) of one of said terminal bodies (CTi ), induced by a first disorientation of its outer portion (PEi) relative to its inner portion (P1), to determine the corresponding axial dimensional change and generate a control current to the transducer (Ti'j) of the other terminal body (CTi ') so that it converts it into an axial dimensional change making it possible to induce a second disorientation of the external part (PEi') of its terminal body (CTi ') with respect to its internal part (PIi' ), opposite to said first disorientation.

4. Device according to claim 1, characterized in that each free space (Si) of terminal body (CTi) houses at least first (Ti1) and second (Ti2) piezoelectric transducers intended to operate in an antagonistic manner, and in that said control means (MC) are arranged, when a measurement current is received from the first transducer (TM) of one of said terminal bodies (CTi), induced by a first disorientation of its external part relative to at its inner part, to determine the corresponding first axial dimensional change and to generate i) a first control current to the second transducer (Ti2) of the same terminal body (CTi) so that it converts it into a second dimensional change axial axis of opposite sign to said first axial dimensional change and of the same amplitude, ii) a second control current to the first transducer (Ti'1) of the another terminal body (CTi ') so that it converts it into a third axial dimensional modification making it possible to induce a second disorientation of the external part of its terminal body (CTi') with respect to its internal part, opposite to said first disorientation, and iii) a third control current to the second transducer (Ti'2) of this other terminal body (CTi ') so that it converts it into a fourth axial dimensional change of sign opposite to said third modification axial dimension and the same amplitude.

5. Device according to one of claims 1 to 3, characterized in that each free space (Si) of terminal body (CTi) houses three piezoelectric transducers (Tij) placed at 120 ° from each other.

6. Device according to claim 5, characterized in that said control means (MC) are arranged, when receiving at least one measurement current from at least one of the transducers (Tij) of the one of said terminal bodies (CTi), induced by a first disorientation of its outer portion relative to its inner part, to determine each corresponding axial dimensional change and generate i) a control current to each transducer (Tij '), this same terminal body (CTi), having not transmitted a measurement current, so that it converts it into an axial dimensional modification, and ii) control currents intended for the three transducers (Ti'j) of the other terminal body (CTi ') so that they convert them into axial dimensional modifications making it possible to induce a second disorientation of the external part of their terminal body (CTi') with respect to its internal part, opposite to the said first disorientation.

7. Device according to one of claims 1 to 6, characterized in that at least one of said inner portion (P1) and outer (PEi) of each terminal body (CTi) is a platform of selected shape, and in that that the intermediate part (PDi) of each terminal body has a diabolo type shape.

8. Device according to one of claims 1 to 7, characterized in that said transducers (Tij) are made of a piezoelectric material selected from a group comprising at least piezoelectric single crystals and piezoelectric ceramics.

9. Device according to claim 8, characterized in that said transducers (Tij) consist of at least one stack of at least one layer of said piezoelectric material.

10. Device according to one of claims 1 to 9, characterized in that it comprises at least one sensor arranged to deliver signals representative of at least one physical quantity, and in that said control means (MC) are arranged to determine said modifications axial dimensions as a function of said signals.

11. Device according to one of claims 1 to 10, characterized in that said control means (MC) are arranged to be activated and deactivated at selected times.

12. Device according to one of claims 1 to 11, characterized in that said control means (MC) are arranged to operate in position control mode.

13. Equipment (E1, E2), characterized in that it comprises at least one fixing device (D) according to one of the preceding claims.

14. Use of the fixing device (D) and the equipment (E1, E2) according to one of the preceding claims, in the spatial field.