WO2017178942A1

WO2017178942A1 - An active support for a photo/film shooting and/or targeting device

Info

Publication number: WO2017178942A1
Application number: PCT/IB2017/052018
Authority: WO
Inventors: Matteo GORETTI; Tommaso ROSSI
Original assignee: Marvegy S.R.L.
Priority date: 2016-04-11
Filing date: 2017-04-07
Publication date: 2017-10-19
Also published as: ITUA20162472A1

Abstract

The present invention relates to supports for shooting systems and/or targeting systems and more specifically it relates to an active support based on a parallel kinematic configuration, moved in active positioning and/or active stabilization by a linear actuation system comprising particular linear actuators specially designed to prevent the support from being back-drivable under any operating condition. The supported devices, hereinafter referred to as "instruments", may for example include photo/video cameras, telescopes, binoculars, instruments and equipment with a viewfinder or other optical and non-optical targeting devices, signal detectors/capturing devices from an external optical, sound, electromagnetic source, pointers (such as laser pointers), equipment provided with a targeting or viewing system, target aiming systems.

Description

TITLE

AN ACTIVE SUPPORT FOR A PHOTO/FILM SHOOTING AND/OR TARGETING

DEVICE

DESCRIPTION

Technical field of the invention

The present invention relates to supports for photo/film shooting and/or targeting systems and more specifically it relates to an active support based on a parallel kinematic configuration. The supported devices, hereinafter referred also to as "instruments", may for example include photo/video cameras, telescopes, binoculars, instruments and equipment with a viewfinder or other optical and non-optical targeting devices, detectors/capturing devices of signals from an external optical, sound, electromagnetic source, pointers (such as laser pointers), equipment provided with a targeting or merely viewing system, target aiming systems.

Background of the invention

The use of moving photo-video shooting systems (transported by operator or positioned on moving means) has always posed the problem of shooting by moving the camera in a smooth manner, i.e. without imparting abrupt movements and avoiding undesired oscillations. To work around this problem, camera supports are available which are provided with photo-video setup stabilizers that essentially belong to two categories:

- passive stabilizers;

- active stabilizers.

Examples of camera supports provided with passive stabilizers are shown in figures 1 a and 1 b. They are based on inertial principles and for this purpose on the use of a counterweight adapted to reduce the abrupt movements that the camera may undergo during its displacement.

These systems are essentially composed of a balanced rod, at one end of which the camera is mounted. At the opposite end, a counterweight is mounted, which must be calibrated for the support to be gripped at the centre of gravity. The support can be directly held by the operator through a handle made up of three joints, and it allows reducing the rotation movements around the axes of an Eulerian reference system (so- called roll, pitch and yaw movements). In more complex systems, the support can be hooked to a body harness through an isoelastic arm (figure 1 b); in this case, the linear movements along the above axes are also reduced and dampened. A first drawback of these systems derives from their weight, clearly resulting from the presence of the counterweight and its infrastructure.

Moreover, these supports are back-drivable, this meaning that they cushion the stresses to which the camera is subjected, but do not oppose to continued stresses such as the pressure of a button on the camera itself or in general a contact stress such as that required for manual focus. In addition, the operator can impart a desired movement to the instrument only by relying on his manual ability, making sure that no undue displacements are caused when acting on the same instrument.

As for the active stabilizers, an example of support with active stabilizer is shown in figure 2. It allows stabilizing movements around the three axes of the Eulerian reference system, in this case expressly represented and indicated by X, Y and Z (roll, pitch and jaw axis, respectively). Typically, these supports comprise a frame with handles to be supported with one or two hands, which by means of an appropriate link of rotatable joints (one per axis) supports a platform over which the camera is placed. The latter must be centred on the intersection of the three axes so that the system is perfectly balanced.

An electronic control circuit continuously monitors the inclination and acceleration variations to which the camera is subjected by means of inertial sensors grouped into a so-called Inertial Measurement Unit (IMU), and consequently drives motors placed at each axis joint X, Y and Z in order to reduce oscillations. Unlike the passive stabilizers, the electronics allows not only keeping the camera levelled but also optionally setting up a specific inclination.

Like the supports with passive stabilizers, the active systems currently on the market are back-drivable, both when the control system is on and all the more when it is switched off: the motors are used to counteract the oscillation of the instrument, and therefore to maintain the balance thereof, countering or following its inertia. Therefore, they are not normally designed to shift the weight, nor are they able to provide a torque adapted to oppose a force that tries to move the platform, such as that resulting from contact stresses as already mentioned. In any case, the switched off system, i.e. without power supply, is completely labile and therefore completely useless even as a static support.

Because of their configuration and of the fact that, as explained above, they cannot oppose to continuous forces, and considering also the force of gravity as a continuous force, in the above known systems any possible unbalance of the instrument inevitably leads to a loss of the system setup. For this reason, the supports currently on the market require a scrupulous mechanical balancing before they are used. In the case of supports with passive stabilizers, it is necessary to place the camera and the counterweight in perfect balance, or the camera may be inadvertently displaced. This is an operation that requires high precision and consequently it is time- consuming and to be performed at every possible change in the weight and/or position of the camera. In any case it requires continuous recalibration, for example as the environmental conditions vary. Moreover, the platform supporting the camera is by its nature free in its motion around balance.

In the case of supports with active stabilizers, the stabilization is even more complicated since the centre of gravity of the camera needs to be perfectly aligned with the intersection point of the rotation axes, which is not easily detectable and is located through empirical attempts. In addition, the motors have the sole function of damping the oscillations.

In both of the above solutions, it is therefore necessary to physically act on the instrument during its use with extreme delicacy. For example, even focusing, zooming in or pressing a button may cause unwanted movements of such an extent as to disturb the shooting. Moreover, it is not possible to change the setup of the camera (for example, changing the focal length of a variable focal lens and extensible barrel) or add accessories without having to balance the system again, because any change in weight or position of the centre of gravity will affect the stabilization.

Moreover, current supports do not allow for substantial customizations in the system response modes to external perturbations. The systems behave as defined by the manufacturer and do not allow significant modification possibilities to the user.

Furthermore, the weight is not negligible, especially in the supports with passive stabilizers, which in any case constitutes an obstacle in the movements of the operator. Consequently, the use in reduced spaces is extremely difficult, when not even unmanageable.

Ultimately, as stated above, the supports currently available are not versatile in the sense that they are to be understood as an aid for a specific shooting use requiring only the camera leveling; for example, it would be impossible to shoot details while keeping the camera still and actuating the focusing. Moreover, due to the total weight and type of stress the operator is exposed to, they cannot be used for lengthy periods of time. Summary of the invention

With the aim of solving the above problems, the applicant has devised a support suitable for supporting cameras, but more generally instruments that pose similar use requirements, which is never back-drivable and which allows imparting a desired dynamic to the instrument, thus practically eliminating all the negative aspects shown by the prior art and mentioned above.

This remarkable result has been achieved by means of an active support for shooting and/or targeting systems of the type defined in claim 1 , based on a parallel kinematic configuration, moved in active stabilization by a linear actuation system comprising particular linear actuators specially designed to prevent the support from being back-drivable in any operating condition, i.e. to make it resist to sustained stresses, such as pressing a button on the instrument, shifting the centre of gravity by adding/removing accessories or changing configuration, or still contacting the instrument itself for some manual adjustment.

The claims as attached are an integral part of this description and are incorporated herein by reference.

Brief description of the drawings

Figure 1 a and figure 1 b show known passive stabilizing supports for cameras.

Figure 2 shows a known active stabilizing support for cameras.

Figures 3a, 3b, 3c show a perspective, front and upper view, respectively, of a particular embodiment of a support according to the present invention.

Figure 3d shows a perspective view of the support in an arbitrary operating position with represented Eulerian reference systems on a base body (X₀, Y₀, Z₀) and on a mobile platform (X, Y, Z).

Figures 4a and 4b show a perspective and longitudinal sectional view, respectively, of a linear actuator adopted in the support shown in the previous figures.

Figure 5a shows a perspective view in isolation a cardan suspension or gimbal, adopted as an end joint in the actuators referred to in the previous figures according to an embodiment of the invention.

Figures 5b to 5d show possible alternative embodiments of the gimbal with respect to the embodiment in figure 5a.

Figure 6 is a top plan view of the base body and relevant gimbals of the support according to figures 3a to 3d, represented in isolation to better highlight the arrangement of the gimbals and consequently of the actuators. Figure 7 is a perspective view of a hypothetical support according to a less preferred embodiment of the invention, with the actuators arranged in a radial arrangement, in an operating position which highlights the problem of mechanical interference that with such an arrangement would occur between the actuators themselves.

Figure 8 shows a further perspective view of a support according to a further embodiment of the invention.

Figure 9 is a perspective view of a support according to yet another embodiment of the invention, which is a variant of the embodiment in figure 8.

Figure 10 is a top plan view of the support in figure 9.

Detailed description of the invention

An embodiment of a support according to the present invention is shown in figures 3a to 7. As mentioned at the outset of the present description, and starting from the observation of known supports for shooting camera, the support according to the invention is intended as active support for a wide variety of shooting and/or targeting devices. For this reason, reference will be made hereafter to the shooting (such as a camera) and/or targeting device supported by the support as a generic "instrument".

The support according to the invention is based on the use of a closed parallel kinematic configuration, also referred to as "generalized Stewart platform", with multiple degrees of stabilization. According to the non-limiting example shown, the configuration is of the type also referred to as a hexapod, with six supports and consequent degrees of movement/stabilization of the system, defined by six linear actuators (3), interposed between a base body (2) and a mobile platform (1), both typically but not necessarily disc-shaped.

The mutual position and inclination of the actuators allows for the movement of the mobile platform on each of the six degrees of freedom (linear and angular movements with respect to the three axes of the Eulerian spatial reference system X, Y, Z) independently. The six-support solution is therefore the most natural, satisfying the need for stabilization on six degrees of freedom, with the consequent presence of as many linear actuators that can, for the configuration in which they are positioned, move or stabilize the mobile platform according to the three main linear motions and the as many three main rotations.

The support permits to control the attitude of the mobile platform with respect to the base using an attitude measurement system, such as an IMU unit, rigidly mounted on the strucure and configured to detect rotations and accelerations around and along the geometric axis, respectively. This system employs, in particular, attitude sensors comprising three gyroscopes (one for each Eulerian axis) and three accelerometers (one for each Eulerian axis) capable of precisely providing the extent of the disturbances the mobile platform undergoes as a result of the motion of the base body.

A control algorithm interprets these measurements and translates them into motion signals for moving the actuators. This control allows total customization of the response of the actuators and their speed and acceleration response curve. The result is that the user has the capability to customize the stabilizing effect by managing, for example, the acceleration smoothness or the motion swiftness, with immediate effect on the quality and the character that can be given to the film or photographic shooting (in the typical but still exemplifying case in which the instrument is a film or photo camera).

The support is totally portable (due to its compact size and weight) and is powered by energy storage batteries such as simple batteries housed in the base body (2). The electronic control system is designed and implemented, both at the software and at the hardware level, according to features that are apparent to a man skilled in the art on the basis of the foregoing description, and therefore not further detailed.

In order to obtain a completely non-back-drivable system, i.e. with stiffness such that it does not allow the mobile platform (1) to be displaced by the weight of the load or by other external forces on it with respect to the base body (2) even when the same system is not powered, according to an aspect of the invention, the linear actuators (3) have a novel and advantageous arrangement here devised to this purpose.

Each linear actuator works according to the following principle: an endless screw (4) is set into rotation by a driving means, such as an electric motor (5) with shaft parallel to the screw axis and connected thereto, and more precisely to a first end thereof, through a transmission (6), such as geared or with belt and pulleys. A nut screw (7) that is inserted on the endless screw (4) responds to the rotation of the screw (4) itself with a translation and is connected to a stem (8) extending coaxially to the screw and which clearly translates in turn with the nut screw.

Through an appropriate inclination of the threads of the screw, the nut screw can translate only if the endless screw itself is set in rotation, while it does not allow the endless screw to rotate by simple effect of the linear pressure (along the axis of the screw itself) applied to the nut screw (retrograde motion); the motion is therefore non- back-drivable. In particular, a sizing adapted to achieve such a result is one that satisfies the equation:

f ≥ tan( ) · cos (a_n)

wherein

f = friction coefficient between the threads of the screw and the nut screw;

tan( ) = tangent of the inclination angle of the screw helix;

cos(ocn) = cosine of the inclination angle of the thread flank seen in a sectional plane normal to the helix of the thread.

The above components are housed and supported (with structural expedients, in particular bearing means, known per se) in an elongated box-like frame (9), with a wider first section starting from a first end and in particular housing the motor (5) and the transmission (6), and a narrower transversal second section ending with a second open end, from which part of the stem (8) projects, guided in its sliding by a bush arranged to delimit the perimeter of the opening.

The connections of said first end of the frame (9) and of the free end of the stem

(8) of each actuator respectively with the base body (2) and the mobile platform (1), are carried out by means of articulated joints (10) and (1 1) which, according to another aspect of the invention, are adapted to achieve maximum saving in terms of bulk. Their functionality prevents the translations in all three axes of the Eulerian system (X_g, Y_g, Z_g) and also prevents the rotation about the longitudinal axis of the endless screw (4), i.e. axis Z_g in figure 5a. A preferred embodiment solution in particular involves the use of a cardan suspension gimbal of particular compactness with respect to a generic cardan joint.

Each linear actuator is thus restrained at its ends so as to reduce the overall bulk of the support and ensure the instability of each joint head according to only two axes of rotation.

In greater detail, see in particular figure 5a but also figures 5b to 5d, each joint can be provided with a first hinge (19), for example consisting of two pegs (12) projecting towards the inside, connected with the respective end of the actuator, and a second hinge (20), for example consisting of two pegs (13) projecting outwards, connected with the base body (2), in case of the lower gimbal (10), or with the mobile platform (1), in case of the upper gimbal (11), the two hinges having coplanar and mutually orthogonal axes. The pegs (or equivalent systems) may extend from a ring- like frame (figure 5a), an open fork frame (figure 5b), a cup frame with complete (figure 5c) or incomplete (5d) development. With the open fork or incomplete cup frame, there will be a single peg (13) and thus a cantilever mounting of the actuator on the base body or on the mobile platform.

In all cases, the hinges constrain the translations and rotation around axis Z_g but the end of the actuator is allowed to rotate along the other two axes of rotation, those passing through the centres of the connecting pegs, thus allowing the actuators to tilt freely.

The actuators (3) are arranged between the base body (2) and the mobile platform (1) so that the axes of the respective stems form a mesh having a cylindrical/conical envelope; in practice, by orderly numbering the actuators with progressive indexes 1 , 2, 3, 4, 5, 6 (figure 3c), the bases (first ends) of the actuators in position 1 , 3, 5 are contiguous to the bases of the actuators in positions 6, 2, 4, respectively, and vice versa: the upper ends of the actuators, or more precisely of the stems (8), in position 1 , 3, 5 are closer to the upper ends of the actuators in position 2, 4, 6, respectively. In this way, the support is stable on all six degrees of freedom.

In the exemplifying configuration referred to above, the actuators (3) and in particular the respective box-like frames (9) have as mentioned a first section, adjacent to the base body (2) which is enlarged, resulting in a base whose footprint, i.e. the outline on the extension plane of the base, has a major dimension or axis (15) that is parallel, in this case coinciding, with respect to the first hinge axis (19), and a minor dimension or axis (16) orthogonal to the first, and therefore parallel to the second hinge axis (20). To ensure that their placement on the base body occupies the minimum space possible, the actuators, according to a preferred and advantageous solution, are therefore arranged in alternating orientation, that is, taking the major axis as a reference - with orientation that alternates between one actuator and the next one, showing an angle that is closer to the tangential direction and one that is closer to the radial direction (reference is made to the circular or oval profile of the disc-shaped base body, or even possibly of an enveloping path that circumscribes the bases of the actuators), all this in order to let the actuators better fit together without mutually interfering during the movement.

To better understand this arrangement and its meaning, reference shall be made in particular to figure 6. Considering the geometric centre of gravity of the sum of the bases the actuators, indicated by the point (18) substantially at the centre of the base body (2), and considering then a purely radial straight line (R2) passing through the point (18), a fictional assumption will be made to align with such a straight line the major axis (15), or more generally its projection onto plane X₀, Y₀ according to the axis of the actuator. With respect to such a hypothetical position, the bases of the actuators will instead advantageously have a rotated arrangement, alternately between consecutive actuators, by an angle of value (a) and by an angle of value (β), where (a) is in a neighbourhood of 90° (about ± 10°) and (β) is preferably of between 0° and 30°. This rotation will be generically meant around a point inside said major axis, optimizable depending on the circumstances. In particular, considering the depicted, non-limiting example, such a point may coincide with the projection onto plane X₀, Y₀ of the centre of rotation of the gimbal (10), i.e. the point (14) of intersection between the first hinge axis (19) and the second hinge axis (20). In case of spherical joint, such a point may also coincide with the projection onto axis X₀, Y₀ of the centre of the joint. In the embodiment shown, it can be seen that, by way of example only, the bases of the actuators in position 1 , 3, 5 are oriented at an angle (a) and the bases of the actuators in position 2, 4, 6 are inclined by the angle (β).

This setup achieves the important result of allowing the mutual approach of the actuators without any profile interference. Figure 7 helps understand how, in the hypothetical case of axial-symmetric positioning of the actuators, such as that with all the major axes arranged radially on the base body, if trying to preserve the compactness of the system, there would problems of mechanical interference between the actuators themselves (conflict areas highlighted by circles I), and conversely, wanting to avoid the latter criticality, the bulk would increase. The above hypothetical positioning, that for the reasons just explained is clearly less preferred, falls nonetheless within the more general scope of the present invention. It is also noted that the above described advantageous geometrical configuration, which achieves a surprisingly effective functional result in relation to the problems posed by actuators with base sockets with elongated footprint (i.e. defined by a major axis and a minor axis) can be implemented irrespective of use of cardan joints, in particular those of gimbal type, since for example it can be associated, in principle, as mentioned, also to spherical joints or joints with multiple and mutually skew axes of rotation.

As regards the upper ends of the actuators, these may be advantageously grouped on the upper platform (1) in pairs substantially aligned according to radial directions (R1), as in the example shown in figure 8, where the concept of radiality refers to the circularity of the platform outline, or in any case of a path that circumscribes it (the outline of the platform, as well as of the base, can clearly be subject to many variations). This embodiment, regardless of the organization of the supports on the base body, can allow reducing the overall dimensions of the base body by maintaining the working angle of the actuators unchanged (angle optimized in advance based on the actual functional requirements), and thus preserving the system stiffness and efficiency. In fact, keeping the angle constant, the lower gimbals (10) may be even closer, with the upper gimbals (11) that still remain distinct and independent.

Still referring to the upper ends, always as part of a conceptually radial solution, that is, a generic alignment of each pair according to a direction that goes from a more centred point to a less centred point, the embodiment shown in figures 9 and 10 specifically referred to hereinafter, may be further advantageous.

In such a variant here considered, the upper end pairs of actuators, in turn generally provided with joints which are not necessarily of the cardan type, are arranged such that the segment joining their centres (also herein more generally interpreted in terms of the relative projection on the plane XY) is deviated angularly from the radial direction (R1) passing by the middle point of said segment (or relative projection on the said plane), by an angle (y) comprised between 0° and 45°, including the extremes, and according to a particularly preferred solution of 10° ± 5°.

In the particular (non-limiting) case of a cardan joint, such a straight line segment (22) is the one that in each pair of joints joins the intersection points (14') between the first hinge axis and the second hinge axis (not shown again here for clarity of illustration, being it immediate to refer to the above description and illustrated in particular in figure 5a in relation to the configuration of the joints). Considering then the midpoint (23) of such a joining segment (22), this is actually the geometric centre of gravity of the pair. Therefore, the above mentioned angle (y) is that formed by the radial direction (R1) exiting from the centre (21) of the platform (1) and passing by said midpoint (23).

With this particular solution, the advantage already mentioned above of reducing the footprint of the base body while maintaining the working angle of the actuators unchanged is still achieved, but the capability of the system to move without interference is even further increased. In particular, in fact, in the case of rotations or translations of the upper platform and, more markedly but not exclusively, in the case of rotations along the axis Z (figure 3d), the stems (8) follow the rotation of their upper ends (1 1), said ends being constrained to the mobile platform (1). As this rotation or translation value of the mobile platform (1) is increased, the stems become mutually inclined but the angular deviation of the joining segment (22) with respect to the purely radial direction allows achieving a reduction of the overlap of the stems (8), i.e. an increase of the minimum distance between the same, bringing them back to a condition of non-interference (in figure 9, see the detail highlighted by the circle W). The interference will therefore only occur at higher values of rotation or translation of the mobile platform (1), allowing greater freedom of movement thereof. The rotation or translation value of the upper platform at which such interference occurs is variable and depending on the circumstances it relates to the geometry of the actuators and the dimensions of the stems.

A further advantage of this solution is the reduction of the required size of the mobile platform (1), since the angular deviation of the joining segment (22) described above permits to locate the upper end of the actuator, namely the one in the outermost position, closer to the virtual centre of the mobile platform (1).

The support as described above thus makes it possible to solve many of the problems associated with the use of existing stabilizers. It does not need to be balanced, that is, there is no need for the centre of gravity of the load to be positioned on the mobile platform (1) in a precise position, since even with the system turned off, the fact that the actuators are not back-drivable makes them equivalent to rigid rods, thus the system is not deformed by the applied load, being in fact a statically stable structure. Conversely, with the system in a switched-on condition, for the same principle the actuators support the load on the mobile platform and easily act on the possible imbalance with differentiated thrusts. A first advantage that can be inferred form this is that the instrument can be easily and quickly installed on the mobile platform without taking care of balance.

Based on the design of the actuators, the system is not back-drivable. Even when switched off, while lacking the "active" control part, it maintains its structure rigid and so it is still usable by the operator as any rigid support, or it allows the operator to switch it off temporarily for different shooting conditions or simply to save operating energy autonomy. The system configuration therefore provides a further advantage to the operator, namely to be able to intervene by touching and even pushing on the instrument while using the system, or instantly add accessories to the same (thus shifting the centre of gravity thereof), or use for example variable focal lenses with lengthening of the barrel which therefore affect the centre of gravity of the system.

Another advantage of the solution is the complete customizability of the stabilizing response of the mobile platform; in particular, since the system is controlled by an algorithm that translates the measurements from attitude sensors into signals for the handling of linear actuators, the response, i.e. the characteristics of such signals, is totally customizable by the user, with control of speed and accelerations/decelerations of the response of the system to attitude perturbations, plus the ability to achieve particular effects of stabilization and repositioning with dedicated response curves suitable also to characterize the style of shooting.

The support as described ensures a high portability and ergonomics, while ensuring a stabilization on six axes/degrees of freedom (three translations and three rotations), and can be kept in hand possibly with the help of appropriate accessories and still very close to the operator, allowing fine control of the shooting. Its reduced weight and size allow use thereof in small spaces and for long periods. Its weight is limited, counterweights not being necessary as in rocker systems and the current technology allows having very limited weight components.

Compared to the current stabilizing systems, and in particular the known solutions, the present solution allows, in addition to the portability and ergonomics features, maintaining an instrument stable in an arbitrary position with respect to the ground, with the particularity of having rigidity to external load variations such as manipulation or load imbalance (being it not back-drivable) and customizing the stabilization response curve by acting on the control parameters and obtaining characteristic effects or performance.

By way of summary, the support according to the invention, in comparison to known solutions and contrary to them, has the following advantageous features.

- The support is statically stable and never back-drivable, whether the control system is active and when it is switched off; the support is not therefore subject to deformation induced by imbalance or user's actions.

- The initial set-up does not require precise and balanced placement of the instrument supported and therefore the start-up timing is minimized, the operations for positioning the instrument being particularly simple.

- Possibility to act on the instrument during the shooting.

- Possibility to change the position of the centre of mass of the instrument (for example, adding accessories or modifying the configuration of the instrument) without the need to rebalance the system.

- Small bulk, ease in shooting operations even in confined spaces.

- Highly customizable stabilization response mode of the support.

As already noted, the support according to the invention can express its advantageous features in relation to support needs of different devices, and consequently the physical interface modes, particularly of the mobile platform (1) and the base body (2) with the user and/or the installation context will vary according to purely constructive adaptations which can be customized from time to time according to the specific needs.

With obvious changes to the control system, by virtue of its structural and operating features, the active support according to the invention will obviously extend its use from the stabilization function to those of positioning and handling, allowing the control of the attitude of the device or instrument, rotating or translating it as desired regardless of the stabilization function and possibly without it and in a fixed position on a plane or a tripod.

The present invention has been described so far with reference to preferred embodiments thereof. It is understood that there can be other embodiments within the same inventive core, all falling within the scope of protection of the following claims.

Claims

1. An active support for a shooting and/or targeting device, comprising:

a parallel kinematic structure with multiple degrees of freedom having:

- a base body (2),

- a plurality of linear actuators (3) mounted on said base body (2), and

- a mobile platform (1) held by said linear actuators (3) and adapted to bear said device;

control means functionally connected to said linear actuators (3);

each of said linear actuators comprising:

- driving means (5),

- a nut screw (7) fixed with a stem (8) configured to sustain said mobile platform (1),

- an endless screw (4) coupled with the nut screw (7) and configured to be rotationally driven by said driving means (5), in which the coupling between said screw (4) and said nut screw (7) is further configured so as to prevent a mutual movement following a direct stress load parallel with the screw axis.

2. The support according to claim 1 , wherein said parallel kinematic structure is a generalized Stewart platform with six linear actuators (3).

3. The support according to claim 2, wherein said linear actuators (3) are configured such that the respective stems form a mesh having a cylindrical or conical envelope, in which each actuator has a connection end to said base body (2) and a connection end to said platform (1) that is close respectively to the respective end of a previous actuator and of a following actuator, or vice versa, considering the sequence of actuators along the envelope.

4. The support according to any of the previous claims, wherein said driving means comprise a motor (5) with a shaft parallel to the axis of said endless screw (4), transmission means (6) being also provided, which operates between said motor and a first end of said endless screw (4).

5. The support according to claim 4, wherein said actuator comprises a box-like frame (9) having an elongated shape, with a wider first section starting from a first end, linked with said base body (2) and housing said motor (5) and said transmission means (6), and a transversally narrower second section with an open second end, from which a part of said stem (8) projects in a slidable fashion to link with said platform (1).

6. The support according to claim 5, wherein the profile of each actuator on the extension plane of the base body (2) has a major dimension or axis (15) and a minor dimension or axis (16), said actuators being arranged so that the orientation of said major axis (15) alternates between one actuator and the next adjacent one, with an angle closer to the tangential direction and one closer to the radial direction.

7. The support according to claim 6, wherein said major axes (15) are angled with respect to the radial direction, alternatively between one actuator and the next adjacent one by an angle (a) of 90° ± 10° and an angle (β) of between 0° and 30°.

8. The support according to claim 7, wherein in each actuator, said major axis is angled around the projection of a rotation centre of the actuator end onto the extension plane of the base body.

9. The support according to claim 8, wherein each actuator (3) is connected to said base body (2) by means of gimbals (10) adapted to allow only two degrees of freedom, that is rotations around respective Eulerian axes lying in an extension plane of the base body or platform, said rotations being realized by a first hinge axis (19) and a second hinge axis (20) respectively parallel to said major dimension or axis (15) and said minor dimension or axis, said rotation centre being represented by the intersection point between said first hinge axis (19) and said second hinge axis (20).

10. The support according to any one of claims 3 to 9, wherein the upper ends of the actuators are grouped on said mobile platform (1) in pairs defining straight segments (22) joining the respective centres, said segments (22) forming with respective radial directions (R1) passing through respective midpoints of the segments themselves an angle (y) comprised between 0° and 45°, extremes included.

1 1. The support according to claim 10, wherein said angle (y) is 10° ± 5°.

12. The support according to claim 10 or 1 1 , wherein each actuator (3) is connected to the said mobile platform (1) by means of gimbals (11) defining a first hinge axis and a second hinge axis, said straight segments (22) joining in each pair the intersection points (14') between said first hinge axis and said second hinge axis of the gimbals, said angle (y) being formed by said joining segments (22) with respective radial directions (R1) passing through the midpoints of said segments.

13. The support according to any one of the previous claims, comprising energy storage means for powering said driving means.

14. The support according to any of the previous claims, further comprising attitude sensor means configured to detect rotations and accelerations of the support respectively around and along at least one geometric reference axis, said control means being programmable to implement, in operation, a drive control algorithm of the extension of the linear actuators (3) based on signals generated by said attitude sensor means to tilt the mobile platform (1) with respect to an inertial reference system with a dynamic set by a user.

15. The support according to claim 14, wherein said attitude sensor means comprise an accelerometer and a gyroscope for each geometrical reference axis.

16. The support according to claim 14 or 15, wherein said attitude sensor means are associated to said mobile platform (1).