This application is a 371 of PCT/EP2011/050785 filed Jan. 20, 2011, which in turn claims the priority of de 10 2010 005 586.7 filed Jan. 22, 2010, the priority of both applications is hereby claimed and both applications are incorporated by reference herein.
The invention concerns a hexapod, comprising a preferably plate-shaped receptacle, on which at least five, preferably six rods mounted in separate joints are arranged, wherein the other end of each rod is articulated on a mounting, wherein all the mountings can be moved along a path of movement.
A hexapod is a means of positioning or control by which it is possible to change the spatial position of any given object situated on the preferably plate-shaped receptacle. For this, the plate-shaped receptacle is articulated to at least five, preferably six rods of constant length, mounted in separate joints, wherein the other end of each rod is articulated on a mounting. Each mounting is arranged movably on a common circular rail, and so it can travel along the circular path of movement defined by the circular rail. Movement of the mountings necessarily changes the spacing of the rod ends articulated to them, while the spacing of the rods also necessarily changes the angles of the respective rods to each other and thus the spatial position of the rod joints located on the receptacle. In this way, all six degrees of freedom of the movable plate can be controlled. However, due to the guidance of the mountings on a common circular rail, the possible positions assumed are limited, and special positioning tasks cannot be accomplished with such a hexapod.
Thus, the problem of the invention is to indicate an improved hexapod.
To solve this problem, for a hexapod of the kind mentioned above, the invention specifies that each mounting is arranged on a separate support, and either the respective mounting is movable along the respective support or the respective support is movable together with the associated mounting, where a support is a ring or a ring section or has a two-dimensionally or three-dimensionally convoluted spatial form, defining a closed or open path of movement.
In the invented hexapod, the “rigid” tying of the mountings to only a single circular-path support that is known from the prior art is eliminated. According to the invention, each mounting is arranged on a separate support, that is, there are at least five, preferably six, separate pairs of mounting and support. This yields two different movement options for the moving or positioning of the receptacle. According to the first alternative of the invention, the respective mounting can be moved along the respective support. That is, the mounting moves along the respective support in the manner of a truck or carriage. The second alternative calls for moving the respective support along with the mounting which is then firmly arranged on it, thus moving the support in space, resulting in a positioning of the rod.
The “decoupling” of the mountings by assigning or arranging them each on a separate support specific for the mounting enables any desired design of the particular mounting-specific support in its geometry or spatial arrangement. For unlike the prior art, in the hexapod of the invention a circular-path support no longer needs to be provided or used. Instead, depending on the required positioning task to be performed with the hexapod, one can readily employ supports of different geometrical design, so that any desired spatial paths of movement of the individual mountings result, depending on the geometry of the support. This necessarily means that the most diverse movements of the receptacle can be implemented. But the hexapod of the invention equally enables the use of supports of identical geometry, even supports in the shape of a circular ring, each of them carrying a mounting and being necessarily arranged staggered from each other in space. That is, ultimately, with the hexapod of the invention, any desired geometrical configurations and spatial arrangements of the individual supports relative to each other are possible, yielding a great variability in terms of the design of the hexapod and the handling of the most diverse positioning tasks. This is shown not least by the fact that as may be provided for in accordance with the invention, the supports can be arranged in the same horizontal plane, in parallel horizontal planes, or tilted relative to each other, and of course any desired “mixed” support arrangements in space are also possible. That is, supports of any given geometry (such as ring, ring section, many-curved supports) can be positioned alongside each other in the same horizontal plane, or arranged with a vertical offset in parallel horizontal planes. In addition, it is also possible to position the supports in a tilted position relative to each other. That is, ultimately, any given possibilities of arranging the supports in space are granted.
As described, supports of any given geometry can be used. A preferred support design is that of a ring. For example, it is possible, when using six rods, to use six separate rings, each one carrying a mounting, being arranged for example vertically one above another in parallel horizontal planes. Either the individual mountings can move on the rings fixed in position, or the rings are individually movable along with the mountings; in this case, they can turn about a common axis of rotation. Alternatively to the ring shape, it is also possible to design a support as a ring section. Such a ring section can extend, for example, over an angle of 120° or 180°. These ring sections can also be distributed in any given manner in space, for example (comparable to the exemplary embodiment with the rings arranged one above another) they can be arranged vertically one above another in horizontal planes lying one above another, being arranged with staggering from each other in the peripheral direction. Other spatial distributions in other planes or the like are also conceivable. Finally, each support can also have a two-dimensionally or three-dimensionally convoluted shape, and thus be convoluted in the manner of a “spline”.
An especially preferred embodiment calls for arranging the rings or ring sections concentrically one above another, that is, positioning them in parallel horizontal planes one above another, wherein they can then turn about a common central axis of rotation. But it is also conceivable to arrange them all lying concentrically within each other in the same horizontal plane, i.e., when using six rings for example, to position these lying concentrically within each other. Here again, the rings can turn about a common central axis of rotation. A combination of both arrangement alternatives is also possible, so that the rings or ring sections are arranged vertically and radially staggered from each other, thus yielding an arrangement that is tiered from top to bottom, for example.
Another problem with a known hexapod, as described in the introduction, and which thus has a common circular ring path on which all the mountings are movably guided, is that each mounting is connected to its own driving means, i.e., its own drive motor, which is moved along with the mounting. This means that not only the mountings, but also their drive motors, are moved along the circular ring rail, and these will mesh by a gear mechanism with a corresponding circular ring rail toothing, for example. Since each drive motor is connected with a cable, when the receptacle is rotated by 360°, which is quite possible, and all mountings thus travel through 360° on the circular path, the cables will get coiled up. That is, the possibility for 360° turns is limited. To remedy this, an especially advantageous modification of the invention calls for each movable support or each movable mounting to be separately movable by its own stationary driving means, or for two supports or mountings to be coupled together in movement, especially by a preferably shiftable transmission, so that they can move via a shared stationary driving means. Thus, in the hexapod of the invention, the driving means such as a drive motor or servo-motor is stationary and consequently not moved. It is coupled in suitable manner with the movable support or the movable mounting, as shall be discussed further below. Nevertheless, it is stationary regardless of the infinitely complex movement of the support or mounting, and so does not move along with them. As a result, any desired movements are possible, without the danger of cable coiling. This is of special advantage particularly in the configuration of the invented hexapod with six ring paths, i.e., circular rings lying one within another or standing one above another. For this configuration enables a 360° turning of the hexapod or the receptacle, and infinitely many 360° turns of the invented hexapod are possible without danger of cable coiling.
There are two different configurations that are conceivable in this case. According to the first one, each support or each mounting can move separately by its own driving means, i.e., its own motor. In this case, thus, six stationary drive motors are provided. But it is also conceivable according to the second alternative to couple two supports or two mountings together in movement so that they can be moved by a common stationary driving means. In this case, thus, only three servo-motors would be provided, while each servo-motor accomplishes the movement of two supports or mountings. The motion coupling can be done, for example, through an intervening transmission, which can also be shiftable, for example, in order to disengage one support or one mounting from the movement when it is supposed to move separately. The transmission can be such that the supports or the mountings can be moved in opposite directions, or in the same direction.
To enable the movement of the supports, according to one modification of the invention each movable support can have a toothing, which meshes with a takeoff element driven by the stationary driving means, i.e., the stationary motor. This takeoff element can be, for example, a pinion or a spindle, while the motor is coupled either directly to the pinion or the spindle, or it is coupled to it by a flexible drive shaft, for example, and arranged externally. Instead of a pinion or a spindle, a belt or chain drive is also conceivable, that is, each movable support has a belt, e.g., in this case a toothed belt wrapped around it, which is driven by the stationary motor. Thus, a direct motion coupling can be realized, via pinion or spindle, or an indirect one via a belt or a chain.
In the case of circular rings or ring sections lying concentrically one above the other, one expedient modification of the invention calls for having the toothings on the outside or inside. Consequently, the driving means, or servo-motors, are located outside or inside the layout of concentric rings or ring sections. In the case of rings or ring sections lying in one horizontal plane, the toothing is located preferably on the underside, so that consequently the servo-motors are also situated in this area. If the support is not round, e.g., an oval support or one describing any given spatial curve, it is possible when using a belt drive to turn it about a central axis, in which case the belt is then wrapped around the support on the outside.
If the mounting can move along the support, it is advisable to move it with a traction means led along the support and coupled to a motor. Such a traction means can, once again, be a belt or a chain, arranged for example inside the hollow support. A movable mounting in this case is configured, e.g., as a carriage, which is movably guided on the support by rollers, other roller bearings, or else sliding hearings, and connected by a suitable coupling to the belt or the chain.
In order to ensure the mobility of the supports, the invention moreover calls for placing the movable supports, especially rings or ring sections, via bearing means, on one or more stationary structural parts, or to have them be movable relative to each other by bearing means arranged between them. Basically all possible kinds of bearings are conceivable here, as long as they enable the separate movement of the individual supports. Ball bearings, roller bearings, sliding bearings, pneumatic bearings, magnetic bearings, etc., can be used, being designed according to how the supports are mounted and able to move relative to each other.
The movable supports, especially the rings or ring sections, can in a first alternative of the invention each have a bearing arm, and all bearing arms are mounted via bearing means on a common central pillow block. For example, if the supports are rings, then each ring has a bearing arm extending inward to the center of the circle, where all bearing arms of the, say, six rings are mounted on a common central pillow block via suitable rolling bearings. However, the circular shape of the ring is not a prerequisite. Instead, this type of bearing is in principle possible for all shapes of supports. The supports can be arranged in different horizontal planes, e.g., lying vertically one above another. But it is also conceivable to use such a central pillow block for ring supports lying in the same horizontal plane, and then the bearing arms are designed with a corresponding angle in order to lead them to the central pillow block.
When the hexapod is designed with concentric rings of the same diameter, it is possible to mount these, as a further bearing alternative, with their outsides on at least three pillow blocks by respective bearing means at the block side. The rings are arranged one above another; radially inside or outside the ring layout are three equally spaced pillow blocks with corresponding bearing means on which the rings roll. A simple bearing layout can also be accomplished in this way. Alternatively, there is the possibility of also placing the bearing means between the individual rings, for example, in the form of axial bearing races with any desired shapes of rolling elements.
Finally, it is advisable to provide a common control mechanism, one that controls all driving means and enables a highly precise positioning of the individual mountings, whether by moving the respective supports or by moving the mounting itself, in order to be able to set the desired positions of the receptacle. However, it should be mentioned here that basically and especially when the hexapod is configured with rings arranged vertically one above another, a manual mobility of the rings can also be provided, insofar as they are movable, or of the mountings, insofar as these can move along the rings.
Further advantages, features and details of the invention will emerge from the below-described example embodiments, as well as the drawings. There are shown:
Each support 3 is firmly joined to a mounting 8, so that the mounting is moved with the support along a circular path upon a rotation of the support 3. The mountings have an L-shape in cross section, they have an inner fastening segment 9 (see
In order to be able to move the individual supports 3 and, thus, the individual mountings 8 separately about the central axis of rotation, each individual support 3 is matched up with a separate driving means 16 in the form of a servo-motor 17. The servo-motors 17, see
The hexapod 1 of the invention makes possible, with its six separate driving means 16, control of a total of seven degrees of freedom. On the one hand, the receptacle 15 can be displaced in the horizontal plane about the X axis and rotated to a limited extent about the X axis. Likewise, the receptacle 15 can be displaced in this horizontal plane about the Y axis and rotated to a limited extent about the Y axis.
Furthermore, the receptacle 15 can also be displaced about the vertical Z axis, but on account of the stationary arrangement of the driving means 16, which therefore cannot be moved and consequently their cable supply lines 18 cannot be coiled up, it can rotate without limit about this receptacle-based Z axis (which thus vertically intersects the flat receptacle 15). In addition, however, the receptacle 15 can also be turned as often as desired about the central vertical Z axis of the hexapod, about which all of the supports 3 thus rotate. That is, two unlimited 360° rotations about two different Z axes, namely, on the one hand the receptacle-based Z axis, on the other hand the central Z axis of the hexapod itself, are possible. Both rotations are possible without limit solely via the six driving means, since these do not move and consequently neither does a coiling of the cable supply lines 18 occur. However, the full rotation of the receptacle 15 about its own Z axis is not possible in all possible positions of the receptacle 15, since there is a limit to the travel bounds of the six mountings 8. However, an unlimited 360° rotation is easily possible if the receptacle 15 is not tilted too much from the horizontal. On the other hand, the rotation about the central axis of rotation of the hexapod itself is possible in every position of the receptacle 15, since all six mountings 8 are moved with the same motion profile, that is, all supports 3 are moved homogeneously with the same velocity or acceleration.
From here, the receptacle 15 was brought into the greatly tilted position shown in
In order to be able to lift the receptacle 15 slightly again, yet once more adjust it in its spatial position as regards its own flat plane, two mountings 8 of the triplet shown at left in
The pivoting of the six supports 3 in the example embodiment shown takes place on a total of three pillow blocks 34, each having several rollers 21, there being a total of six rollers 21 in the example shown. The pillow blocks 34 are arranged equidistant in the area of the outside of the supports 3, being positioned at a 120° offset from each other on the hexapod housing 2 (which can also be a frame or the like). The individual supports 3 are pivoted on or at the rollers 21, for which the supports 3 have a corresponding outer profile, so that they can slide against the rollers 21. In any case, this “three-point bearing” realizes a complete pivoting of each individual support 3.
To drive the individual supports 3, which again can be driven separately and consequently the individual mountings 8 can travel along a circular path, a total of six separate driving means 16 in the form of servo-motors 17 are provided once again. These motors are again disposed in stationary fashion on the housing 2. The driving of the supports in the example shown occurs each time by a belt 22, which is wrapped around the outside of the respective support 3. Since the supports 3 are arranged one above another, and consequently positioned in different horizontal planes, the servo-motors 17 also are arranged with a vertical offset (also see embodiment 1 per
On the outside of each support 3 there is arranged a mounting 8, solidly in rotation, for which a radially outwardly pointing projection 28 is provided on each support 3—see the sectional view per FIG. 17—on which the respective mounting 8 is fastened. In operation, the mountings 8 consequently move along the outer periphery of the ring structure.
Due to the stationary arrangement of the servo-motors 17 and the fastening of each mounting 8 to a separate support 3, unlimited 360° rotations are again possible, at the same time as extremely flexible positioning possibilities.
Since the supports 3 in the example embodiment 19 shown—which of course is in no way limiting for the support shape, but instead any given support contours are conceivable—have a contour deviating from a circular path, once again totally different positioning options necessarily result from the path geometry.
Although the option exists to move each of the bracelike supports 3 in a horizontal plane, and preferably the individual horizontal planes are vertically staggered relative to each other so that the supports 3 do not run into each other, in the example embodiment shown in
Although
Finally, it should also be noted that instead of rings, the supports can also be configured as ring sections or ring segments. For example, a ring segment may describe 120° or 180°. Such ring segments can be arranged vertically one above another, for example, as in the embodiment of
The hexapod of the invention in its different embodiments (of course, the example embodiments shown are in no way limiting) enables a highly accurate and highly flexible positioning of the receptacle 15. Any given implements can be arranged on the receptacle 15. These can be small and miniature implements, for example, surgical and working means to be used in medical technology, or tools and tool holders to be used in machining, through to large structures such as telescopes or satellite dishes or simulators such as flight simulators, helicopter simulators or automobile simulators. Consequently, its use is possible wherever a movement about six—or with the hexapod of the invention even seven—degrees of freedom is required and especially where 360° rotations are required in any desired number.
Number | Date | Country | Kind |
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10 2010 005 586 | Jan 2010 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2011/050785 | 1/20/2011 | WO | 00 | 7/20/2012 |
Publishing Document | Publishing Date | Country | Kind |
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WO2011/089198 | 7/28/2011 | WO | A |
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