WO2003086717A1 - Hybrid parallel manipulator for moving a workhead in space - Google Patents

Abstract

Disclosed is a device for moving a workhead in space. Said device is able to span a large volume and provides easy access to the workhead, wherefore the device is provided with a platform (30) which is arranged in a first plane and is movable in two dimensions. Said platform (30) supports a swiveling element (40) which is pivotable around an axis of rotation and on which at least two bars (52, 54, 55) are disposed. Said bars (52, 54, 55) are movable relative to the swiveling element (40) and support a mounting device (60) for a workhead or a workhead.

Description

This international search report has been prepared by the International Searching Authority and will be transmitted to the applicant in accordance with Article 18. A copy will be sent to the International Office.

This international search report comprises a total of _4 sheets.

| X] In addition, a copy of the state-of-the-art documents mentioned in this report is enclosed.

1. Basis of the report a. With regard to the language, the international search was carried out on the basis of the international application in the language in which it was submitted, unless stated otherwise under this point.

D The international search was carried out on the basis of a translation of the international application submitted to the authority (Rule 23.1 b)). b. With regard to the nucleotide and amino acid sequence disclosed in the international application, the international search has been carried out on the basis of the sequence listing that

] | is contained in the international application in written form.

| | has been filed with the international application in computer readable form.

I | has subsequently been submitted to the authority in writing.

| | has subsequently been submitted to the authority in computer-readable form.

| | The declaration that the subsequently submitted written sequence listing does not go beyond the disclosure content of the international application at the time of filing was submitted.

| | The explanation that the information recorded in computer readable form corresponds to the written sequence listing has been submitted.

2.] | Certain claims have proven to be non-researchable (see field I). 3. | | Lack of uniformity of the invention (see field II).

Regarding the designation of the invention

| | the text submitted by the applicant is approved. [X ~] the wording was determined by the authority as follows: HYBRID PARALLEL MANIPULATOR FOR PROCESSING A WORKING HEAD IN SPACE

5. With regard to the summary ryi, the wording submitted by the applicant is approved. the wording has been determined by the authority in accordance with Rule 38.2b) in the version specified in field III. The | | Applicants can contact the authority within one month of the date of dispatch of this international

Submit a research report an opinion.

6. The following illustration of the drawings is to be published with the summary: Fig. No. _J

| X | as suggested by the applicant Q none of Fig. 1 | because the applicant did not propose a picture himself. ] | because this figure better characterizes the invention.

Form PCT / ISA / 210 (Sheet 1) (July 1998) HYBRID PARALLEL MANIPULATOR FOR MOVING A WORK HEAD IN A ROOM

description

Technical field of the invention

The invention relates to a device for moving a working head in space according to the preamble of claim 1.

Subject of the invention

Nowadays, workpieces are often processed fully automatically using CNC-controlled machines. For this purpose, it is generally necessary to be able to move a working head in all three spatial directions, and it is often still necessary to additionally arrange the working head so that it can be rotated or pivoted along two axes. To achieve this, two fundamentally different concepts are known in technology:

In one class of such devices, the end of a column is moved in space by means of three orthogonal tracks. A hinge is usually arranged at its end, the axis of which is parallel to the column. A fork head joint adjoins this swivel joint, the axis of rotation of which is perpendicular to the axis of rotation of the swivel joint. The working head in question is finally arranged on this fork head. The working head can thus be moved Cartesian in space and still be oriented in space, although the swivel angle of the clevis joint is often limited to approximately 180 °.

The working head therefore has 5 degrees of freedom, three transitory and two rotary. The degrees of freedom are completely decoupled from one another, which makes the control of the device relatively simple. In addition to this relatively simple control, devices of this type have the further advantage that almost any volume can be spanned, so that even very large workpieces can be processed. This is possible in particular if the corresponding device is constructed in the manner of a portal robot.

In addition to this advantage, such devices naturally also have disadvantages, two of which are particularly important for the following. In order to make the column that supports the swivel sufficiently stable against lateral forces that occur, it must generally be dimensioned relatively strong, which naturally leads to a correspondingly high mass. Since this column must of course be moved during operation (it usually serves as the Z axis), correspondingly large masses must be accelerated, which has the known disadvantages with regard to the dimensioning of the motors and the maximum achievable working speed.

The Z-pillar also blocks direct access to the working head. This can be very cumbersome in numerous applications, e.g. when a laser beam is to be fed to the working head, which is then directed onto the workpiece via a mirror system, or when a high-pressure line, for example for supplying paint, plastic or water, is to be connected to the working head.

So-called multipodes, in particular hexapods, are also known. Here 6 bars are pivotally and slidably arranged on a basic element. The ends of these rods are in turn movably connected to a common fastening element, which in turn carries the working head. Such a hexapod is described, for example, in DE 196 49 082 C1. - 3 -

Although hexapods are more difficult to master in terms of control technology, they have the advantage of very high mechanical stability with low mass. Furthermore, the working head moved by the Hexapod is usually very easy to reach on the direct center line. A major disadvantage of multipods for many applications is that the volume that can be achieved with them is relatively small, which means that they cannot be used to machine large workpieces.

For some special applications, devices have become known which combine the multipod principle with the principle of a Cartesian / rotary machine. DE 43 06 332 A1, for example, describes a device which is used to change measuring and / or test probes. This device has a turntable in which a drive unit is pivotably arranged via two telescopic legs. The turntable can be moved in a longitudinal direction.

A spherical hexapod is known from DE 196 40 769 A1. In this document, u. a. proposed to provide this multipod with a further linear or rotary degree of freedom.

Subject of the invention

Based on this prior art, it is an object of the invention to provide a device for moving a working head in space, which receives the advantages of a Cartesian / rotary machine shown above, in particular with regard to the large spanned volume, but allows easy direct access to the working head.

Another object of the invention is to reduce the mass to be accelerated without losing mechanical stability. This object is achieved with a device having the features of claim 1.

The device according to the invention has a platform which is arranged to be 2-dimensionally movable in a first plane. This is usually the horizontal X-Y plane. This can be done in the manner of a portal robot, so that the area that can be painted over can be chosen practically as large as desired. This platform carries a rotating element which can be rotated about an axis of rotation, to which in turn a multipod is fastened, which in turn carries a working head or a mounting device for a working head. This multipod is responsible for moving the measuring head in the third spatial direction, usually the Z direction, and for pivoting it at least along one axis.

The particular advantage of a classic Cartesian / rotary device is obtained by the device according to the invention, namely the possibility remains to machine workpieces of almost any size. The fact that the direct connection to the working head or its assembly device takes place via a multipod allows, on the one hand, direct access to the working head, which, as already explained above, offers considerable advantages in some applications. Furthermore, the advantages that a multipod has with regard to the relationship between mass and mechanical stability can be exploited, at least with regard to two degrees of freedom.

According to claim 2, the movement of the platform can be carried out with the help of a portal robot, the plane of movement of the platform preferably being a horizontal plane.

Claims 3-5 give a particularly preferred embodiment in which the multipod is kinematically a dipod, but is constructed as a tripod for reasons of statics. Here, a first rod is at a fixed angle to the rotating element, preferably at a right angle. In relation to the rotating element, this first rod can therefore only perform a pure axial movement. The other two rods are arranged symmetrically and ensure the tilting of the working head or its mounting device along an axis which is preferably perpendicular to the axis of rotation of the rotating element. Furthermore, the direction of the first linear movement (Y direction), the direction of the second linear movement (x direction) and the axis of rotation of the rotary element are each orthogonal to one another.

According to claim 6, the first track projects laterally beyond the second track, which makes it possible to make the entire work area, which is spanned between the second tracks, accessible.

Description of preferred embodiments

The invention will now be explained in more detail using an exemplary embodiment with reference to the accompanying figures. Show it:

FIG. 1 shows a perspective basic illustration of the device according to the invention,

FIG. 2 shows the partial view T from FIG. 1,

FIG. 3 shows a basic illustration of the mounting of the first rod in the rotating element in cross section,

FIG. 4 shows a basic illustration of the mounting of a second rod in the rotating element in cross section,

FIG. 5 shows an enlarged partial view from FIG. 1.

Figure 1 shows a simplified representation of a preferred embodiment of the invention. A rotary element in the form of a turntable 40 is horizontally displaceably mounted on a first raceway 10 (Y direction). through - 6 -

two vertical struts 11, 12, the first raceway 10 is displaceably mounted on the two second raceways 20 in a second direction (X direction), the two running directions being vertical to one another. This structure corresponds to that of a portal robot known in the art and it is achieved in that the platform 30 can be moved in the horizontal X-Y plane. The corresponding electric motors that are necessary to carry out the movements are not shown in FIG. 1.

A turntable 40 which is rotatable by means of an electric motor (not shown) and whose axis of rotation is perpendicular to the two directions of movement shown above is mounted in the platform 30.

At the turntable 40 three rods are each slidably arranged. This is the vertical rod 52 and the two oblique rods 54, 55. The rods each extend essentially downwards and the ends of the rods 52, 54 and 55 are connected in an articulated manner to the mounting device 60, see FIG. 2. The mounting device 60 and its connection to the rods 52, 54, 55 will be discussed in more detail later The storage of the rods 52, 54, 55 in the rotary tele 40 is first explained in more detail with reference to FIGS. 3 and 4:

In Figure 3, the storage of the vertical rod 52 in the turntable 40 is shown schematically in a cross section. A first bearing sleeve 42 is rigidly installed in the turntable 40. The axis of this bearing sleeve extends parallel to the axis of rotation of the turntable 40. The vertical rod 52 is displaceably arranged in this first bearing sleeve 42 so that it can carry out a movement in the Z direction. The vertical rod 52 can be activated, for example, by means of an electric motor M, which engages with a toothing Z in a toothing 52a of the vertical rod 52. - 7 -

FIG. 4 shows the mounting of the inclined rods 54, 55 in the turntable 40. These bearings are each constructed identically, since the two inclined rods 54, 55 are also arranged symmetrically with respect to the vertical rod 52 and are also operated synchronously. The two inclined rods 54, 55 are also each supported by means of a sleeve (second sleeve 44), the respective inclined rod being able to perform an axial movement with respect to this second bearing sleeve 44. In contrast to the mounting of the vertical rod 52, however, the second bearing sleeve 44 is not rigidly connected to the turntable 40, but is gimbally connected to the turntable 40 via a swivel plate 45. The universal joint itself is not shown in Figure 4. This cardanic suspension allows the inclined rods 54, 55 to be pivoted in any direction with respect to the turntable 40. The diagonal bars are also driven here in each case by an electric motor M which is arranged in such a way that it follows the tilting movements of the diagonal bars. The need for the gimbal mounting of the oblique rods 54, 55 can be seen when looking at FIG. 2:

The vertical rod 52 is connected to the L-shaped connecting bracket 64 of the mounting device 60 via a first joint 66. The pivot axis of this first swivel joint 66 lies in the horizontal plane. The Z position of the mounting device 60 is changed by the axial displacements of the vertical rod 52. The two inclined rods 54, 55 must follow this movement, which of course changes their angle with respect to the turntable 40. To compensate for this, the gimbals mentioned above are necessary.

The two inclined rods 54, 55 are connected to the connecting bracket 64 via second joints 67. These second joints 67 must not have rigid axes and can be designed, for example, in the form of ball joints. The assembly device 60 is pivoted in a vertical plane by a synchronous displacement of the two inclined rods 54, 55. Overall, the required 5 degrees of freedom are achieved. With suitable di - 8th -

dimensioning of the components, a swivel range of significantly more than 180 ° can be achieved.

The 3-leg coupling of the assembly device 60, on the assembly section 62 of which any work head, for example a milling head, a spray head, a laser processing head, a water cutting head, etc. can be coupled has the following advantages in particular:

First, the central axis that extends from the turntable 40 to the working head is kept clear. This is very helpful if, for example, a laser beam or liquid must be supplied to the working head under high pressure by means of a pressure pipe. Here, it would also be conceivable, for example, to provide a central opening in a specially shaped mounting device through which the desired medium can be fed directly to the working head and only needs to be deflected in one swivel plane.

Furthermore, the arrangement proposed here is very stable against lateral forces at a low weight, so that only relatively small masses have to be accelerated without loss of precision, which means that the corresponding servomotors can be dimensioned small and a high working speed is made possible. In order to achieve a further reduction in weight, it is conceivable to manufacture the rods from carbon fiber or a fiber-reinforced plastic.

The arrangement of one of the rods at a fixed angle, preferably the right angle, with respect to the turntable 40 has two advantages in particular. On the one hand, a collision of one of the rods with the workpiece to be machined can thus be reliably prevented. If all three rods were gimbaled, which is also possible, and can also bring advantages in certain applications, namely when a sixth degree of freedom is required, the head should always be moved 9

note that none of the bars collide with the workpiece. This would be very difficult in terms of control technology. In the example shown here, it is only necessary to ensure that the vertical rod always points in the direction of the workpiece. It is easy.

Furthermore, the regulation is also simpler overall, since a displacement of the vertical rod corresponds exactly to the z-movement of the working head.

- 10 -

LIST OF REFERENCE NUMBERS

10 first career

11, 12 vertical struts

20 second career

30 platform

40 turntables

42 first bearing sleeve

44 second bearing sleeve

45 swivel plate

52 vertical rod

54 first diagonal bar

55 second diagonal bar

60 mounting device

62 Installation section

64 connecting bracket

66 first joint

67 second joint

Claims

11Patentansprüche 1. Device for moving a working head in space with: - a platform (30) which is arranged to be two-dimensionally movable in a first plane, characterized in that the platform (30) carries a rotating element (40) which can be rotated about an axis of rotation, - on which is arranged at least two rods (52, 54, 55) which can be displaced with respect to the rotating element (40) and which in turn carry an assembly device (60) for a working head or a working head itself. 2. Device according to claim 1, characterized in that the platform (30) can carry out a first linear movement on a first track (10), wherein the first track can carry out a second linear movement on a second track (20). 3. Device according to claim 1 or 2, characterized in that a first rod (52) is at a fixed angle to the rotating element (40), while the second rod is at a variable angle to the rotating element. 4. The device according to claim 3, characterized in that the fixed angle is selected so that the first rod (52) extends parallel to the axis of rotation. 5. Device according to one of claims 3 or 4, characterized in that there are two second rods (54, 55) which are arranged symmetrically and whose movements are synchronous. 12 Device according to one of the preceding claims, characterized in that the rods (52, 54, 55) consist of carbon fiber or a fiber-reinforced plastic.