6-axis positioning system with locking component

Abstract

A 6-axis positioning system (1) with a base (2) and a movable unit (3) and six variable-length actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3), one end (8, 12) of which is connected to the base (2) and the other end (9, 14) of which is connected to the movable unit (3), wherein at least one additional variable-length component (16) is provided, one end (17) of which is connected to the base (2) and the other end (18) of which is connected to the movable unit (3), and wherein the additional component (16) is designed such that a releasable locking of the 6-axis positioning system (1) is possible at least in certain positions of the movable unit (3), characterized in that the additional component (16) has a releasable locking brake (19), that the The variable-length component (16) is designed such that it can be passively moved by means of the movement of the six driven actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3) length-variable, that the six actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3) are divided into two groups (4, 6), that the actuators (5.1, 5.2, 5.3) of the first group (4) are arranged within an area bounded by the actuators (7.1, 7.2, 7.3) of the second group (6) on the base (2) and on the movable unit (3), and that the three actuators (5.1, 5.2, 5.3) of the first group (4) are designed as heavy-duty actuators that are stronger than the three actuators (7.1, 7.2, 7.3) of the second group (6).

Description

[0001] The present invention relates to a 6-axis positioning system comprising a base, a movable unit and six variable-length actuators, one end of which is connected to the base and the other end of which is connected to the movable unit, wherein at least one additional variable-length component is provided, one end of which is connected to the base and the other end of which is connected to the movable unit, and wherein the additional component is designed such that a releasable locking of the 6-axis positioning system is possible at least in certain positions of the movable unit.

[0002] These 6-axis positioning systems, also known as hexapods, offer six degrees of freedom of movement in a compact space. The movable unit typically consists of a platform (movable unit) connected to the upper end of the actuators, on which the elements or structures to be positioned are arranged. Six-axis positioning systems are available in various sizes and for a wide range of applications. As components in industrial production processes, hexapods position even heavy loads with sub-micrometer accuracy. For industrial applications, combinations of absolute position sensors, suitable software, and motion controllers are available, allowing for the convenient execution of even complex motion profiles. Brushless DC motors with brakes are a preferred drive for the actuators. The working range of such a 6-axis positioning system depends heavily on the telescoping capability of the actuators.Especially in heavy-duty 6-axis positioning systems, very large actuators are used to achieve the necessary rigidity. This results in increased installation space and higher costs.

[0003] A positioning system of this type is known from DE 10 2004 004 313 A1. This patent describes, among other things, an arrangement with six telescopically length-adjustable rod elements and three additional rod-shaped stiffening elements. All elements extend from a base element to a working element. It further explains that the stiffening is primarily achieved in the working position, while the stiffening effect is reduced in the transition positions between the initial position and the working position. How this stiffening is achieved in detail is not described. However, it is generally stated that the stiffening elements can be adjusted in length in a controllable manner. Actuation can be hydraulic, pneumatic, mechanical, or electrical. Alternatively or additionally to stiffening elements, prestressing elements are also mentioned.

[0004] DE 10 2006 011 823 A1 relates to a positioning device comprising a base plate and a tool plate connected to each other by means of six struts. The struts are grouped into pairs, with each pair of struts having at least a common linkage, a common drive, and a common braking mechanism at the base plate.

[0005] DE 102 55 950 A1 deals with a robot drive that has two sub-drives specialized for their respective tasks. These are a sub-drive for force generation and a sub-drive for position generation. In the specific case (see Fig. 1 and Fig.2) A robot arm is equipped with a power drive consisting of an electric motor with gearbox and an open toothed belt. The toothed belt is pre-tensioned by tension springs. Additionally, a positioning drive is provided, consisting of a conventional DC micromotor with an angle encoder and a high-reduction gearbox. A coupling ensures the appropriate connection between the two sub-drives. A parking brake, e.g., a piezoelectrically actuated brake, is also included and is assigned to the positioning drive.

[0006] CN 107538231 A1 describes a multi-axis positioning device comprising a lower platform, an upper platform, six inclined actuators, and centrally located support columns. The load is primarily supported by the support columns. Each support column includes a linear guide with a hinged joint at its upper end, connected to the upper platform. The linear bearing is supported by a compression spring against a base. The base is mounted and fixed to the lower platform, while the upper part of the support column can move freely relative to the lower platform. The six actuators ensure precise control.

[0007] It is therefore the object of the present invention to provide a 6-axis positioning system of the type mentioned above that ensures good adherence to the target position even under increased loads.

[0008] This problem is solved by a 6-axis positioning system with the features according to claim 1. Advantageous embodiments are described in the dependent claims.

[0009] In a generic 6-axis positioning system, the additional component has a releasable parking brake. The variable-length component is designed such that its length can be passively adjusted by the movement of the six driven actuators. The six actuators are divided into two groups. The actuators of the first group are arranged on the base and on the movable unit within an area delimited by the actuators of the second group. The three actuators of the first group are designed as heavy-duty actuators, capable of handling a higher load than the three actuators of the second group. An additional variable-length component is an element, assembly, etc., in addition to the six actuators. Therefore, the at least one additional variable-length component is something that supplements (in addition to) any locking mechanisms or detents that may be present on the six actuators.Brakes must be present on 6-axis positioning systems. An additional component also offers the advantage that it can be placed elsewhere than the actuators, so that, due to the grouping, distance from the center, etc., of at least one additional component, a significant influence can be exerted on the stiffening of the overall system caused by the locking mechanism. Such a design is therefore particularly suitable for heavy-duty 6-axis positioning systems, because these generally require the use of large, heavy-duty actuators. This results, among other advantages, in the fact that, through additional simple measures, adherence to the target position can be achieved more cost-effectively due to increased stiffness. Preferably, an additional component does not actively participate in the positioning of the movable unit, but rather ensures locking in the predetermined target position.This allows the additional components to behave passively during the movement of the movable unit, for example, being dragged or moved along by the actuators. The parking brake is then activated to lock the unit when the desired target position is reached and released again when it is moved away from this position. The variable-length component does not need its own drive, which in turn saves costs.

[0010] The actuators of different groups are preferably designed differently. This allows the movable unit with its extended working area to be moved around the ends of the actuators of the first group attached to the movable unit. This makes it possible to design these three actuators of the first group to be shorter than the three actuators of the second group and, if necessary, to equip them with greater lifting capacity. A kind of workload distribution between the actuators of the first and second groups is thus possible, resulting in a more compact, and especially flatter, design with an extended working area. In addition, the extra components provide rigidity when the desired target position is reached.

[0011] Although standard and identical parts can be used, it is preferred that the three actuators of the first group and the three actuators of the second group are designed differently. It is possible that the three actuators of the first group have at least twice, and preferably at least three times, the load-bearing capacity of the actuators of the second group.

[0012] Advantageously, the additional component is designed in such a way that a releasable locking mechanism for the 6-axis positioning system is possible throughout its entire working area. This means that at least one additional component is able to follow the movements of the movable unit within the working area and then lock it in the desired target position. The benefits are therefore available throughout the entire working area.

[0013] According to one embodiment, the releasable parking brake is a piezoelectric brake. This can be controlled very precisely, so that the braking process itself does not affect the target position.

[0014] In another embodiment, the releasable parking brake can be a vacuum brake. This is very cost-effective and easy to implement.

[0015] Particularly for reasons of symmetry, it is advantageous if, according to one embodiment, at least two, preferably three, additional length-adjustable components are provided for locking the 6-axis positioning system. The variant in which each pair of actuators is assigned one additional component is especially beneficial. Uniform distribution also ensures uniform stiffening within the respective workspace.

[0016] Accordingly, the additional component can be designed in such a way that, in the locked state, it increases the stiffness and natural frequency of the 6-axis positioning system. This is particularly advantageous for heavy-duty 6-axis positioning systems because even very large loads can be positioned with high accuracy using a more cost-effective 6-axis positioning system.

[0017] Especially in heavy-duty 6-axis positioning systems, very high forces typically act in the vertical direction. Therefore, it is advantageous if the additional component is length-variable and pivotably connected to the base and the movable unit in such a way that the additional component can be arranged to move within an angular range of a maximum of ± 45°, preferably a maximum of ± 30°, relative to a vertical or a perpendicular to a plane spanned by the base. In their home position, the base and the movable unit are generally arranged horizontally, thus establishing an angular reference to a vertical. However, 6-axis positioning systems can, in principle, assume different angular positions; for example, the base can be tilted out of the horizontal or horizontal plane, in which case a reference to a vertical is advantageous. A plane spanned by the base is, for example,defined by a plane containing the center points of the connection points of the additional components or the connection points of the actuators. Additional components arranged in this way have a stiffening effect, particularly with regard to a predominantly vertically applied force.

[0018] Advantageously, the at least one additional component can be positioned further out on the base and on the movable unit relative to the first group of actuators, preferably in the area between the actuators of the first and the actuators of the second group. This ensures that tilting forces, in particular those introduced outside the area supported by the three actuators of the first group, are additionally supported by the at least one additional component. Despite the greater pivoting capability achieved due to the arrangement of the actuators of the first group, stable positioning is still attained.

[0019] In a further embodiment, the actuators of the first group are arranged in such a way that their lengths can be varied and they are pivotably connected to the base and the movable unit, such that each of the three actuators of the first group is movable within an angular range of a maximum of ± 30°, preferably a maximum of ± 15°, relative to a vertical or perpendicular to a plane spanned by the base. The three actuators of the second group are also arranged in such a way that their lengths can be varied and they are pivotably connected to the base and the movable unit, such that each of the three actuators of the second group is movable within an angular range of ≥ 0° to a maximum of 45°, preferably ≥ 0° to a maximum of 30°, relative to a horizontal or parallel to a plane spanned by the base. This arrangement allows the three actuators of the first group to bear a major portion of the load, while the three actuators of the second group primarily serve for positioning.With a corresponding change in the length of the actuators, the relationships shift, whereby the main lifting load is still borne by the three actuators of the first group.

[0020] The at least one additional component then stabilizes the actuator in the respective target position. Due to the specified angle, the three actuators of the second group are generally positioned much flatter than the three actuators of the first group.

[0021] In extreme cases, the three actuators of the second group can therefore lie flat or horizontally in their minimum stroke position and be angled at an acute angle in their maximum stroke position. Overall, this results in a very flat and compact design. With such an arrangement, the three actuators of the second group require a greater travel distance. This is only possible if these three actuators are guided laterally past the three actuators of the first group. Alternatively, they can be guided past at least one additional component, or space can remain between the three actuators of the second group for the placement of at least one additional component.

[0022] The six actuators themselves do not need to be designed to be so rigid as to provide the necessary stiffness and natural frequency of the system in the specified target position. Instead, the actuators can be adapted accordingly with regard to the at least one additional component used, because the stiffness and natural frequency in the target position are increased by means of this at least one additional component. The more complexly designed actuators can therefore be more cost-effective or used in less common groupings without compromising the necessary stiffness and natural frequency in the target position within the workspace.

[0023] The additional component is passively moved along with the movable unit by means of the interaction of the six variable-length actuators. This results in a dragging or telescoping motion without significant resistance or assistance, because the movement of the movable unit is controlled solely by the six variable-length actuators. However, there is also the possibility that at least one movable unit provides damping. The primary function of the movable unit, however, is to lock it in the target position and to increase the stiffness and natural frequency of the system.

[0024] An embodiment of the present invention is explained in more detail below with reference to a drawing. The single figure shows a perspective view of an embodiment of a 6-axis positioning system according to the invention.

[0025] The first embodiment of a 6-axis positioning system 1 shown in the figure comprises a base 2 in the form of a triangular platform and a movable unit 3, also in the form of a triangular platform, as well as actuators arranged between them, which will be described in more detail later. Both the base 2 and the movable unit 3 are each formed by a plate of substantially uniform thickness, preferably made of a metal, e.g., steel. The actuators arranged between the base 2 and the movable unit 3 are grouped into a first group 4 with actuators 5.1, 5.2, and 5.3 and a second group 6 with actuators 7.1, 7.2, and 7.3. Actuators 5.1, 5.2, and 5.3 differ in function and construction from actuators 7.1, 7.2, and 7.3, while the actuators of each group 4 or 6 are identical in construction. Actuators 5.1, 5.2, and 5.3 are arranged in the first group 4 with actuators 5.1, 5.2, and 5.3.Three actuators of the first group 4 are pivotably arranged with their lower ends 8 on the base 2 and with their upper ends 9 on the movable unit 3. The pivoting arrangement is similar to a universal joint (cardan joint), allowing pivoting movements about two axes. For a more compact arrangement, the base 2 has a window recess 10 for attaching the lower end 8 of the actuators 5.1, 5.2, and 5.3, so that one axis of the universal joint is located within the window recess 10. Similarly, the movable unit 3 is provided with three window recesses 11, which serve for the pivoting arrangement of the upper ends 9 of the actuators 5.1, 5.2, and 5.3. Again, one axis of the associated universal joint is fixed in the window recess 11.

[0026] A lower end of each actuator 7.1, 7.2, and 7.3 is pivotably mounted on a bearing block 13 located on the base 2. A universal joint is used for pivoting about two axes. Similarly, an upper end 14 of each actuator 7.1, 7.2, and 7.3 is mounted on a bearing block 15 attached to the movable unit 3. The upper end 14 is also pivotally mounted using a universal joint for pivoting about two axes.

[0027] Due to the chosen arrangement, actuators 5.1, 5.2, and 5.3 of the first group 4 are positioned more upright than actuators 7.1, 7.2, and 7.3 of the second group 6. Window recesses 10 and 11, as well as the two bearing blocks 13 and 15, also facilitate this arrangement. Window recesses 10 and 11 are positioned further inward on base 2 and movable unit 3, respectively, compared to their corresponding bearing blocks 13 and 15. This places actuators 5.1, 5.2, and 5.3 of the first group 4 within an area on base 2 and movable unit 3, respectively, defined by actuators 7.1, 7.2, and 7.3 of the second group 6. Since the load is applied from above via the movable unit 3, it is also possible that the main load is absorbed by the actuators 5.1, 5.2, 5.3. These are therefore designed as heavy-duty actuators, which are significantly more load-bearing than the three actuators 7.1, 7.2, 7.3 of the second group 6.All six actuators are length-adjustable (telescoping) and driven by a brushless DC motor. The basic operating principle and control of 6-axis positioning systems are well-known, so they will not be discussed in detail here. In any case, the movable unit 3 can be raised, lowered, or moved relative to the base 2 and tilted around all three spatial axes. The adjustability of actuators 5.1, 5.2, 5.3 and 7.1, 7.2 and 7.3, as well as their arrangement, determine the possible working range. Due to the drive technology used, very precise control and positioning are possible even in this heavy-duty application.

[0028] In addition to actuators 5.1, 5.2, 5.3 and 7.1, 7.2, 7.3, three additional length-variable components 16 in the form of telescopic units are provided. Like actuators 5.1, 5.2, 5.3 and 7.1, 7.2, 7.3, components 16 are arranged uniformly and symmetrically at both the base 2 and the movable unit 3. The lower end 17 of components 16 is pivotally movable at the base 2, and the upper end 18 is pivotally movable at the movable unit 3. This is done in a manner similar to actuators 5.1, 5.2, 5.3 of the first group 4, in the manner of a universal joint (cardan joint), so that pivoting movements about two axes are possible. The additional components 16 are equipped with a parking brake 19 (e.g. a piezo brake or a vacuum brake) by means of which they can be locked or unlocked at any time.Otherwise, the additional components 16 are freely length-changeable without significant resistance when the parking brake 19 is open, with the length change occurring passively due to the actuation by the actuators 5.1, 5.2, 5.3 and 7.1, 7.2, 7.3.

[0029] In the basic position of the 6-axis positioning system 1 shown in the figure, the base 2 and the movable unit 3 are aligned parallel to each other, i.e., the actuators 5.1, 5.2, and 5.3 of the first group 4 have the same length, and the actuators 7.1, 7.2, and 7.3 of the second group 6 have the same length. Furthermore, actuators 5.1, 5.2, and 5.3 are in their fully retracted position, which is why actuators 7.1, 7.2, and 7.3 are also in their lowest possible downward position. In this basic position, the main axes of actuators 5.1, 5.2, and 5.3 are aligned exactly vertically, i.e., they are perpendicular to a plane defined by the base 2. In this position, actuators 7.1, 7.2 and 7.3 have an angle of approximately 0° to the horizontal or to a parallel to a plane spanned by base 2.

[0030] The additional length-variable components 16 are tilted slightly from the vertical in this position and their upper ends 18 are positioned closer to the upper ends 9 of the nearest actuators 5.1, 5.2, 5.3 of the first group 4 than their lower ends 17 are positioned closer to the lower ends 8 of the nearest actuators 5.1, 5.2, and 5.3 of the first group 4. The angle of inclination to the vertical is approximately 10°. Furthermore, the additional components 16 are positioned further outwards at both the base 2 and the movable unit 3 compared to the actuators 5.1, 5.2, and 5.3 of the first group 4. However, each of these actuators 5.1, 5.2, 5.3 is assigned an adjacent partner (component 16). The placement takes place approximately in the space between two actuators 7.1, 7.2, 7.3 of the second group 6. If the axes of the actuators 7.1, 7.2 and 7.3 of the second group 6 are extended so that they create a triangle, then the actuators 5.1, 5.2, 5.The first group 4 and the additional components 16 are arranged within this triangle. This results in a compact grouping, which, among other things, ensures that a relatively large pivoting motion can occur even with a small stroke of actuators 5.1, 5.2, and 5.3. Nevertheless, precise positioning is possible through the interaction of actuators 5.1, 5.2, and 5.3, as well as 7.1, 7.2, and 7.3.

[0031] In the fully retracted position of actuators 5.1, 5.2 and 5.3 shown in the figure, actuators 7.1, 7.2 and 7.3 of the second group 6 are significantly longer than actuators 5.1, 5.2 and 5.3 of the first group 4. Accordingly, the maximum travel of an actuator 7.1, 7.2 and 7.3 of the second group 6 is significantly greater than the maximum travel of an actuator 5.1, 5.2 and 5.3 of the first group 4.

[0032] The additional components 16 are designed such that, when the movable unit 3 reaches a controlled target position via the actuators 5.1, 5.2, 5.3 of the first group 4 and 7.1, 7.2 and 7.3 of the second group 6, they activate the parking brake 19 and thus stiffen the entire 6-axis positioning system 1. This increases the overall stiffness of the system 1 and its natural frequency, enabling very precise and rigid positioning even under heavy loads.

[0033] The following section explains in more detail the operation and functionality of the illustrated embodiment.

[0034] By selectively controlling the drives of actuators 5.1, 5.2, and 5.3, as well as 7.1, 7.2, and 7.3, the movable unit 3 is positioned precisely relative to the base 2. Six-axis positioning within a predefined workspace is possible. The main load during lifting and lowering is borne by actuators 5.1, 5.2, and 5.3 of the first group 4. These are therefore designed as heavy-duty actuators, enabling the movement of substantial loads. Actuators 5.1, 5.2, and 5.3 of the first group 4 pivot only within a limited angular range with respect to a vertical plane defined by the base 2 (maximum ± 30°, preferably maximum ± 15°). Actuators 7.1, 7.2 and 7.3 also pivot accordingly only by a limited angular range (from ≥ 0° to a maximum of 45°) to a horizontal or parallel to a plane spanned by base 2.

[0035] For example, by shortening or telescoping the actuators 7.1, 7.2, and 7.3 of the second group 6 and correspondingly compensating for the swivel movement and extending the actuators 5.1, 5.2, and 5.3 of the first group 4, the movable unit 3 can be rotated relative to the base 2, even without necessarily changing the distance. Overall, the required travel distance of actuators 7.1, 7.2, and 7.3 is greater than that of actuators 5.1, 5.2, and 5.3.

[0036] The variable-length components 16 are passively moved during these positioning processes. This occurs through compression or telescoping, depending on the direction of movement. Once the desired target position has been reached by means of the actuators 5.1, 5.2, 5.3 of the first group 4 and 7.1, 7.2, 7.3 of the second group 6, the parking brake 19 is engaged and the 6-axis positioning system 1 is locked in the target position. The components 16 are designed such that they significantly increase the stiffness and natural frequency of the 6-axis positioning system 1 in the target position. This is particularly necessary because, in the illustrated embodiment, the actuators 5.1, 5.2, and 5.3 of the first group 4 are positioned more centrally, and therefore movements of the movable unit 3 may be less rigid.Components 16 provide the necessary compensation, enabling even heavy-duty systems to be operated with high precision and control of their target position. As soon as a further operation is required, the parking brake 19 is released and components 16 are passively moved.

[0037] All in all, a 6-axis positioning system 1 is created that is compact, particularly flat, and capable of supporting high loads while maintaining the necessary rigidity. This is achieved through the appropriate grouping and functional division of the two actuator groups 4 and 6, and the use of the lockable components 16. It should also be noted that, for the sake of clarity, the figure omits the illustration of the electrical connections and any other connections, as well as the sensor system. The control and regulation of the illustrated 6-axis positioning system 1 is carried out according to well-established procedures for known systems of this type (hexapods). Reference symbol list 1 6-axis positioning system 2 Basic 3 movable units 4 1st group 5.1, 5.2, 5.3 Actuator 6 2nd group 7.1, 7.2, 7.3 Actuator 8 bottom end 9 top end 10 Window recess 11 Window recess 12 lower end 13 bearing block 14 upper end 15 bearing block 16 components 17 lower end 18 upper end 19 Parking brake

Claims

[1] 6-axis positioning system (1) with a base (2) and a movable unit (3) and six variable-length actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3), one end (8, 12) of which is connected to the base (2) and the other end (9, 14) of which is connected to the movable unit (3), wherein at least one additional variable-length component (16) is provided, one end (17) of which is connected to the base (2) and the other end (18) of which is connected to the movable unit (3), and wherein the additional component (16) is designed such that a releasable locking of the 6-axis positioning system (1) is possible at least in certain positions of the movable unit (3), characterized by, that the additional component (16) has a releasable parking brake (19), that the variable-length component (16) is designed such that its length can be passively varied by means of the movement of the six driven actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3), that the six actuators (5.1, 5.2, 5.3; 7.1, 7.2, 7.3) are divided into two groups (4, 6), that the actuators (5.1, 5.2, 5.3) of the first group (4) are arranged on the base (2) and on the movable unit (3) within an area bounded by the actuators (7.1, 7.2, 7.3) of the second group (6), and that the three actuators (5.1, 5.2, 5.3) of the first group (4) are designed as heavy-duty actuators that are more load-bearing than the three actors (7.1,7.2,7.3) of the second group (6). [2] 6-axis positioning system (1) according to claim 1, characterized by, that the additional component (16) is designed in such a way that a releasable locking of the 6-axis positioning system is possible in the entire working area of ​​the 6-axis positioning system (1). [3] 6-axis positioning system (1) according to claim 1 or 2, characterized by , that the releasable parking brake (19) is a piezo brake. [4] 6-axis positioning system (1) according to claim 1 or 2, characterized by , that the releasable parking brake (19) is a vacuum brake. [5] 6-axis positioning system (1) according to any one of claims 1 to 4, characterized by , that at least two, preferably three, additional components (16) are provided for locking the 6-axis positioning system (1). [6] 6-axis positioning system (1) according to claim 5, characterized by , that the additional component (16) is designed such that, in the locked state, it increases the stiffness and natural frequency of the 6-axis positioning system (1). [7] 6-axis positioning system (1) according to any one of claims 1 to 6, characterized by , that the additional component (16) is connected to the base (2) and the movable unit (3) in such a way as to be variable in length and pivotable, such that the additional component (16) is arranged to be movable in an angular range of at most ± 45°, preferably at most ± 30°, to a vertical or a perpendicular to a plane spanned by the base (2). [8] 6-axis positioning system (1) according to any one of claims 1 to 7, characterized by , that the at least one additional component (16) is arranged at the base (2) and at the movable unit (3) further outwards relative to the first group (4) of the actuators (5.1,5.2,5.3), preferably in the area between the actuators (5.1,5.2,5.3; 7.1,7.2,7.3) of the first group (4) and the actuators (7.1,7.2,7.3) of the second group (6). [9] 6-axis positioning system (1) according to any one of claims 1 to 8, characterized bythat the three actuators (5.1, 5.2, 5.3) of the first group (4) are connected to the base (2) and the movable unit (3) in such a way that their lengths are variable and they are pivotably connected such that the three actuators (5.1, 5.2, 5.3) of the first group (4) are each movable within an angular range of a maximum of ± 30°, preferably a maximum of ± 15°, to a vertical or perpendicular to a plane spanned by the base (2), and that the three actuators (7.1, 7.2, 7.3) of the second group (6) are connected to the base (2) and the movable unit (3) in such a way that their lengths are variable and they are pivotably connected such that the three actuators (7.1, 7.2, 7.3) of the second group (6) are each movable within an angular range of ≥ 0° to a maximum of 45°, preferably ≥ 0° to a maximum of 30°. are arranged in a horizontal or parallel direction to a plane spanned by the base (2) so as to be movable.

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