A DEVICE FOR TORSION-PROOF CONNECTION OF AN ELEMENT IN A ROBOT ARM OR THE LIKE

Abstract: A device for torsion-proof connection of a number of elements (11, 12) in direct or indirect rolling contact with each other, which together make a robot arm or the like, whereby the elements are held together and actuated by force transmitting actuators, for example cords. The object of the present invention is to provide a device with which the individual elements of a robot arm can be torsionally locked so that it can bear significant torsional forces without detoriating the rolling characteristics of the elements. This object has been achieved by the fact that the elements (11, 12; 15) pairwise, with their rolling surfaces (13) turned towards each other, being connected with each other through a torsion member (14) which is flexible and/or jointed in the roling direction of the elements (11, 12) and which has a great stiffness across the rolling direction.

Description: A DEVICE FOR TORS ION-PROOF CONNECTION OF AN ELEMENT IN A ROBOT ARM OR THE LIKE The present invention refers to a device for torsion-proof connection of a number of elements in direct or indirect rolling contact with each other, which together make a robot arm or the like, where the elements are held together and can be moved by force transmitting actuators, for example cords. BACKGROUND OF THE INVENTION In the Swedish patents 7902366-9 and 8001998-7 a robot arm is described which is especially characterized by having a great flexibility in different planes , whereby its ability to get around barriers is great. It can thus be inserted in curved or angled spaces, which previously was almost impossible. The great flexibility of the robot arm is achieved because the arm consists of a large number of disc-like elements which have a rolling contact with each other. An absolute requirement for robot arms of this type is that in addition to a relatively large weight bearing capability at the free end of the arm it be possible to transmit torques and maintain large torsional moments. The relatively poor torsional resistance of cord manouvered robot arms, which is caused by the rounded form of the individual elements, has indeed been improved through providing the rolling surfaces of the elements with teeth or the like, which engage each other, but in many cases another torsion locking of the elements is desirable . THE PURPOSE OF THE INVENTION AND ITS MAIN CHARACTERISTICS The object of the present invention is to provide a device with which the individual elements of a robot arm can be torsionally locked so that they can bear significant torsional forces without detoriating the rolling characteristics of the elements. This object has been achieved by connecting at least the first and the last elements in an element pair or group of elements together through a torsion member which is flexible and/or jointed in the rolling direction of the elements and which has a great stiffness across the rolling direction. DESCRIPTION OF THE DRAWINGS Fig. 1 shows a side view of two cooperating elements provided with torsion members according to the invention. Fig. 2 shows the member according to fig.. 1 in perspective. Fig. 3 shows also in perspective a modified embodiment of the member shown in fig. 2. Fig. * 4 shows a variation of the torsion lock shown in ig. 1 and 2 in perspective. Fig. 5 shows in perspective an embodiment of an element pair where the torque and force bearing members are placed outside the elements . Fig. 6 shows a side view of a number of elements which have their rolling surfaces oriented in the same direction. Fig. 7 shows in perspective an additional embodiment where the torsion member is arranged across the rolling direction of the elemen . Fig. 8 shows in perspective a cross-like embodiment of the torsion member. Fig. 9 shows in perspective and partly in exploded view a modified embodiment of the variant shown in fig. 5. Fig. 10 shows ' an exploded view ' of an embodiment of the cross-like torsion member. Fig. 11 shows in perspective an additional embodiment of the torsion member according to the invention. Fig. 12 shows a side view partly in section of a modification of the embodiment shown in fig. 8 Fig. 13 shows a side view of an embodiment with pivotally connected torsion members. Fig. 14 shows in a perspective an additional embodiment of two elements provided with torsion members according to the invention. Fig. 15 shows in perspective and in section torsion members in O the form of a bellows containing a group of elements. Fig. 16 shows in perspective the lower part of a robot arm with torsion members according to fig. 8. DESCRIPTION OF EMBODIMENTS Fig. 1 and 2 show an embodiment consisting of two identical elements 11 and 12 shaped with single-curved surfaces 13 toward each other, which are in rolling contact with each other and are connected with each other via a torsion member 14. This can consist of for example a steel wire, appropriately of spring steel, which is fastened at one end to the side edge of one element 11 , while the other end is connected to the corresponding side edge of the other element 12 located directly opposite. The connection of the torsion member 14 with the elements can be achieved in a number of different ways, by welding, riveting, screw fastening or through grooves in the elements in which the ends of the members are fixed. The cooperating elements 11 and 12 cooperating in the above described way and the rolling surfaces 13 of which are turned toward each other, are called an element pair in the following. As is clear from fig. 3 the two elements need not be shaped with single- or double curved rolling surfaces, but included in the scope of the invention is the possibility of shaping an element 15 for example as a plane or even slightly * convex or concave curve with significantly larger radius of curvature than the radius of curvature of the other cooperating element. In fig. 3 the torsion member 14 is thus attached to the side edge of the element 11 by one end, while the other end is fastened to the plane element 15. The elements 11 , 12 and 15, on the plane side from the rolling surface 13, are provided with projecting portions 16, which contain holes for receiving the cords (fig. 16) which are acted on by actuators 9 and which connect the first (outer) and last elements in a group of elements. The element pairs can naturally be arranged in other relative rotational positions than the 90° mentioned. The element pairs can for example be rotated only a few degrees relative to each other, so that they are placed in a screw line formation. The torsion member 14 can extend over the whole width of the element, but it can also advantageously be divided into several narrower bands which are alternately connected with respective elements, as is shown in fig. 4. Fig. 5 shows an embodiment where the torsion members are place outside the elements 11 and 12. Each element pair includes two torsion plates 14 a and 14 b, which each include a central middle field 18 and on the sides of that slightly angled side fields 19. At the outer end the torsion plate is provided with a narrow strip 21 which is mainly parallel to the middle field 18. The two torsion plates 14 a and 14 b are connected at the outer edges for example by spot welding and in that way make a torsion member 14. Because the middle field 18 has mainly the same size and shape as the plane "back" surface of the elements 11 and 12 these will be locked against rotation relative to the torsion member. For certain applications it can be appropriate to arrange a group of elements with their rolling planes placed in the same direction as is shown in fig. 6, and in such arrangements it is possible to arrange the torsion member 14 as a continuous length which extends from the first element 11 to the last element 12 in the element group. The parts 19 of the torsion members outside the elements need not necessarily be arranged in the rolling direction of the elements as is shown in fig. 5 but can also be arranged perpendicular to the said rolling direction, according to what is shown in fig. 7. It is also possible to arrange the torsion members in both these directions , that is combination of what is shown in fig. 5 and 7. In fig. 8 is shown an embodiment, where each individual torsion member 14 is cross-shaped and made of an appropriate spring steel material. The cross-shaped member has a central middle part 18, for receiving elements 11 and 12 respectively on each flat sides opposite each other. The elements do not belong to the same element pair but belong to respective pairs. The parts 19 placed outside the elements, that is one arm pair of the cross, are both curved at an angle towards the central part 18, while the other parts 20 are curved in the opposite direction relative to the arms 19. The end parts 19, 20 of the arms are intended to be connected to the arms of the neighboring torsion member. The connection between the arms can be permanent, for example by welds, but other means of connection are possible, for instance screw fastenings. As can be seen in fig. 8 the rolling direction of every second element pair is rotated 90 β relative to each other, so that the arms 19 and 20 respectively are placed in the direction of the extension of the rolling direction. In order to obtain an even stiffer construction a plane plate 22 can be placed between each element pair 11 , 12, preferably of spring steel, which at both its ends is fastened to the ends of the arms 19 and 20 respectively, as is shown in fig. 9. Possibly the parts 19 and 20 can be shaped with stiffeners inserted in the plates, which is indicated on two fields. Fig. 10 shows an embodiment where the same great stiffness is obtained as in fig. 9 but without affecting the flexibility of the arms. This is obtained by replacing the plate 22 in fig. 9 with a plate-shaped frame 23, which at a distance surrounds the element pair 11 , 12. In the same way as the plate 22 the frame is fixed to the arms 19 and 20 respectively of two nearby torsion members 14. further variant of the torsion members is shown in fig. 11 where the members have a partially bellows-like form. Each member 14 contains a plane, for example eight-sided plate 24, which in the same way as the cross-shaped part according to fig- 8-10 is placed between two elements belonging each to its element pair. In the extension of the rolling surface between two neighboring plates 24 are placed connecting pieces 25 with V-shaped cross sections, which are fastened by their shank ends 27 to the edge parts 26 of the plates 24. In fig. 12 is shown a modified embodiment of the device according to ig. 11 , where the fixed connections at the edge parts 27 and the shank ends 26 have been replaced by joint connections 28, 29, for example in the form of piano hinges. Instead of connecting the plates 24 with connection pieces 25 they can be attached to the elements 11 and 12 in a flexible bearing, which is shown in the embodiment according to fig. 13. At the oppositely placed side edges of the elements 11 , 12 are flexibly attached torsion members 14, which consist of two hinge flanges 30 and 31. An additional embodiment is shown in fig. 14. On the end sides 32 and 33 of the elements 11 and 12, across the rolling direction of the elements at the beginning and final ends of the rolling surface, pins 34 are ixed, which act as bearing axles for the torsion members 14, which in this embodiment consist of steel bands 35, which are loop shaped at the ends for fitting the pins 34. In fig. 15 is finally shown an embodiment where a group of elements has a continuous torsion member 14 in the form of a cross-sectionally preferably circular bellows, where the folded bellows sides 38 are made of a stiff material. In this embodiment only the first and last elements of the group are connected with the end pieces 36 and 37 of the bellows, whereby the ends 39 of the wires 10 are attached to the end piece 36. OMPI ( /A) T-O The invention is not limited to the embodiments shown and described, but a number of variations are possible within the scope of the claims. Thus the elements 11 , 12 can be arranged in groups so that their rolling surface is turned in the same direction, said embodiment can be appropriate if the robot arm is to perform a motion only in that direction. In the description and in the drawings only single-curved elements have been shown, but the torsion members according to the invention can of course also be used with elements with double curved rolling surfaces.

Claims: C L A I 1. A device for torsion-proof connection of a number of elements (11 , 12) in direct or indirect rolling contact with each other, which together make a robot arm or the like, whereby the elements are held together by and through actuators which can be actuated by for example cords, c h a r a c t e r i z e d i n, connection of at least the first and last elements (11 , 12) in an element pair or in a group of elements with each other through a torsion member (14) which is flexible and/or jointed in the rolling direction (x-axis according to fig. 2) of the elements (11 , 12) , and which ' has a great stiffness across the rolling direction. 2. A device according to claim 1 , c h a r a c t e r i z e d i n, connection of the elements (11 , 12; 15) pairwise to each other with their rolling surfaces (13) turned toward each other through at least one in a first direction flexible and/or jointed, and in another direction transverse to the first direction stiff, appropriately plate-shaped torsion member (14) . 3. A device according to claim 2, c h a r a c t e r i z e d i n, that each torsion member (14) comprises of at least one band, preferably a steel band, the two ends of which are fastened to at least the first and last elements (11 , 12 and 15 respec- tively) in an element pair or in a group of elements at or near the beginning or terminal end of the respective rolling surface . 4. A device according to claim 3 , c h a r a c t e r i z e d i n, the torsion member (14) comprising several bands (1 a, 14 b, 14 c) which are alternately connected to the respective elements (11 , 12; 15) . - JRE OMPI * • ' 5. A device according to claim 1 or 2, c h a r a c t e r i z e d i n, the torque and force bearing parts of the torsion member ( 14 ) being place outside the elements (11 , 12) . 6. A device according " to claim 5, c h a r a c t e r i z e d i n, the torsion member (14) consisting of at least one bellows, the folded bellows walls (38) of which being made of a stiff material . 7. A device according to claims 2 and 5, c h a r a c t e r i z e d i n, the torsion member (14) consisting of plates (18, 19) extending from each elements (11 , 12) in an element pair which are fixed (21 ) or jointed (28, 29) to each other outside the elements (11 , 1 ) . 8. A device according to claim 5, c h a r a c t e r i z e d i n, the members (14) being cross-like and formed with a central part (18) arranged between two elements (12, 11 ) belonging each to its element pair, and the two arm pairs (19, 20) of the cross-like ma ber* being bent in opposite directions relative to each other, and each arm pair being connected to the arms of a respective corresponding adjacent member. 9. A device according to claim 8, c h a r a c t e r i z e d i n, that between the elements (11 , 12) in each element pair a substantially plane plate (22) is arranged, which is connected by its ends with the arms (19, 20) of the cross-like member. 10. A device according to claim 8, c h a r a..c t e r i z e d i n, a plate-shaped frame (23) being attached between the cross arms (19, 20) of the members (14) connectible to each other an located opposite each other, said frame extending about an element pair (11 , 12). 11. A device according to claim 5, c h a r a c t e r i z e d i n, each member (14) consisting of a substantially plane plate (24) placed between two elements (12, 11 ) belonging each to its element pair (11 , 12) and the plates (24) being equipped in the extension of the rolling surface with V- or bellows-shaped connecting pieces (25) . 12. A device according to claim 5, c h a r a c t e r i z e d i n, pins (34) or the like being placed at the end sides (32, 33) of the elements (11 , 12) substantially across the rolling direction (x) of the elements near the beginning or terminal ends of the rolling surface (13) , at which pins torsion members (14) are arranged, which preferably cross-wise connect the elements in each element pair. OMPI

Inventors: BENGTSSON BENGT GOERAN, LARSSON OVE, LENSCHOW PER, BENGTSSON, BENGT, GOERAN, LARSSON, OVE, LENSCHOW, PER
Applicants: ROBOTGRUPPEN HB
Application year: 1983
Main classification: B25J17
IPC codes: B25J9, B25J17, B25J18