Robot picking assembly

Abstract

A robotic picking assembly (100) comprising an arm support arrangement (8) configured to move vertically and to rotate about a vertical axis. A horizontally extendable arm (1) is supported in the arm support arrangement. A gripping tool (20) arranged at a free end (1a) of the arm. The arm comprises arm modules (2) linked together in a chain. The arm modules (2) have a pivot means (4) linking adjacent arm modules together in a pivoting manner and a pivot restriction means (15, 16, 18, 19) limiting curving of the arm to only one direction. The arm support arrangement (8) has an arm guiding arrangement (25, 21, 21a, 21b, 33) guiding the arm between an extended position and a retracted position, and an arm drive arrangement (7) configured to move the arm between said extended and retracted positions.

Claims

1. A robotic picking assembly comprising: an arm support arrangement configured to move vertically and to rotate about a vertical axis; a horizontally extendable arm supported in the arm support arrangement; a gripping tool arranged at a free end of the horizontally extendable arm; wherein the horizontally extendable arm comprises a plurality of arm modules linked together in a chain, and wherein the plurality of arm modules comprise: a hinge linking adjacent arm modules together in a pivoting manner; and a pivot restriction means limiting curving of the horizontally extendable arm to only one direction; wherein the arm support arrangement comprises: an arm guiding arrangement configured to guide the horizontally extendable arm between an extended position and a retracted position; an arm drive arrangement configured to move the horizontally extendable arm between said extended and retracted positions; and wherein when the horizontally extendable arm is in the retracted position, a portion of the horizontally extendable arm exhibits an upwardly curved shape, extending upwards from a horizontal portion of the horizontally extendable arm, between the free end and a back end, wherein the back end of the horizontally extendable arm is fixed to an end unit of the arm support arrangement.

2. The robotic picking assembly according to claim 1, wherein in the retracted position, the horizontally extendable arm curves at least 180 degrees, preferably at least 270 degrees.

3. The robotic picking assembly according to claim 1, wherein in the retracted position, the horizontally extendable arm curves less than 360 degrees, preferably less than 280 degrees.

4. The robotic picking assembly according to claim 1, wherein the plurality of arm modules comprise a pitch rack and the arm drive arrangement comprises a motorized cogwheel engaging the pitch rack.

5. The robotic picking assembly according to claim 1, wherein the plurality of arm modules comprise an umbilical channel and that an umbilical extends through the umbilical channel to the free end of the horizontally extendable arm.

6. The robotic picking assembly according to claim 1, wherein the back end of the horizontally extendable arm is fixed to the end unit of the arm support arrangement in a vertical orientation.

7. The robotic picking assembly according to claim 1, wherein the plurality of arm modules comprise a stabilizing protrusion at one end and a stabilizing groove at an opposite end, wherein the stabilizing groove is configured to receive the stabilizing protrusion of an adjacent arm module.

8. The robotic picking assembly according to claim 1, wherein the pivot restriction means comprises a rear abutment surface and a front abutment surface, which are configured to abut against each other when adjacent arm modules are in a straight configuration.

9. The robotic picking assembly according to claim 1, wherein the arm guiding arrangement comprises a lower vertical guide wheel supporting the horizontally extendable arm from below and an upper vertical guide wheel supporting the horizontally extendable arm from above, wherein the lower vertical guide wheel is arranged closer to the free end than what the upper vertical guide wheel is when the horizontally extendable arm is in the extended position.

10. The robotic picking assembly according to claim 1, wherein the plurality of arm modules are provided with module rollers configured to engage a roller groove of the arm support arrangement.

11. The robotic picking assembly according to claim 1, wherein the arm support arrangement comprises a roller groove and that the plurality of arm modules comprise pairs of module rollers, wherein a horizontal portion of the roller groove engages the pairs of module rollers, so that a weight of an extended portion of the horizontally extendable arm, as well as the weight of a carried item held by the gripping tool, is carried by an engagement between the horizontal portion and the pairs of module rollers.

12. The robotic picking assembly according to claim 1, wherein the arm guiding arrangement comprises a roller groove having a horizontal portion and a curved portion that curves upwards with respect to the horizontal portion.

13. The robotic picking assembly according to claim 12, wherein a length of the horizontal portion is less than 2.5 module lengths, preferably less than 3.5 module lengths.

14. The robotic picking assembly according to claim 1, wherein the plurality of arm modules comprise a box-shaped module body with two opposite and parallel side walls, and a substantially flat lower surface.

15. The robotic picking assembly according to claim 1, wherein the arm drive arrangement has not more than one electric arm drive motor configured for moving the horizontally extendable arm between the extended and retracted positions.

16. The robotic picking assembly according to claim 1, wherein when in the extended position, at least 50%, more preferably at least 70%, of a total number of the plurality of arm modules of the horizontally extendable arm are arranged along a common straight centerline.

17. The robotic picking assembly according to claim 1, wherein the horizontally extendable arm is without actuators or motors configured to move the horizontally extendable arm, as such actuators or motors are arranged external of the horizontally extendable arm.

18. The robotic picking assembly according to claim 1, further comprising: a vehicle structure with at least three wheels, configured to move the robotic picking assembly on a horizontal surface; a vertical movement arrangement configured to move the arm support arrangement vertically; a rotation arrangement configured to rotate the arm support arrangement about a vertical axis; and a pallet support arrangement configured to support a pallet.

19. The robotic picking assembly according to claim 1, wherein the plurality of arm modules comprise two abutting curve restriction faces configured to restrict curving of two adjacent arm modules beyond 90 degrees, preferably 75 degrees.

20. A computer-readable software embodied on a non-transitory medium and configured to control a robotic picking assembly according to claim 1, when run on a computer, as the software is configured to control: the arm drive arrangement; a rotation motor configured to rotate the arm support arrangement about a vertical axis; a vertical motor configured to move the arm support arrangement vertically; and a vehicle structure configured to move the robotic picking assembly on a horizontal surface.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) While various features of the present invention have been discussed in general terms above, a more detailed, non-limiting example of embodiment will be given below with reference to the drawings, in which

(2) FIG. 1 is a perspective view of a robotic picking assembly according to the present invention, located in the space between two rows of pallet racks;

(3) FIG. 2 is a schematic top view showing the position of the picking assembly in FIG. 1 arranged between the two rows;

(4) FIG. 3 is another perspective view illustrating the situation in FIG. 1;

(5) FIG. 4 is a perspective view illustrating the picking assembly where the arm is in an extended position;

(6) FIG. 5 is a side view of the situation shown in FIG. 4;

(7) FIG. 6 is a perspective view of the picking assembly where the arm is in a retracted position;

(8) FIG. 7 is an enlarged perspective view of a portion of the arm when in an extended position, wherein some components have been removed for illustrational purpose;

(9) FIG. 8 is a view corresponding to FIG. 7, with a portion of the arm removed for illustrational purpose;

(10) FIG. 9 is a perspective view of the picking assembly, shown with a vertical support structure, such as a tower, and means for rotating the assembly about a vertical axis;

(11) FIG. 10 is a cross section side view of the arm and arm support arrangement, showing an umbilical extending through the arm;

(12) FIG. 11 and FIG. 12 are enlarged perspective views of an arm module;

(13) FIG. 13 is another perspective view of another embodiment of the invention;

(14) FIG. 14 is an enlarged perspective view of an arm module according to another embodiment of the invention;

(15) FIG. 15 is an exploded view of the arm module shown in FIG. 14;

(16) FIG. 16 is an enlarged side view of two adjacent arm modules, shown in a maximum pivot position;

(17) FIG. 17 is a cross section side view through the arm support arrangement;

(18) FIG. 18 is a perspective view of an alternative embodiment of the present invention;

(19) FIG. 19 is a perspective view of an alternative embodiment of a tower that may be part of the assembly according to the invention, shown in a vertically extended state;

(20) FIG. 20 is a cross section side view of the tower shown in FIG. 19; and

(21) FIG. 21 is another cross section side view of the tower shown in FIG. 19, however in a vertically retracted state.

DETAILED DESCRIPTION OF THE INVENTION

(22) FIG. 1 depicts a typical application of a robotic picking assembly 100 according to the present invention. The picking assembly 100 is located in a relatively tight space between two rows of pallet racks 200. A plurality of pallets 201 are stored in the pallet racks 200. In the present example the racks are configured for storage of pallets 201 in two vertical levels. On the pallets 201 are various items 203, typically packed in sets of several products. For instance, one item 203 may be a box containing twelve bottles of shampoo, some packs of sugar, or one item 203 may be a box of spare parts, e.g. for household appliances. Typically, each pallet 201 will carry homogenous items 203, i.e. only one type of goods. Thus, there may for instance be one pallet 201 that only carries boxes of shampoo, and three pallets 201 may carry only one type of flour.

(23) To move the robot assembly 100, one can for instance use an automated guided vehicle (AGV) such as the vehicle 300 shown in FIG. 1. The robot assembly 100 has a pallet interface, making it suitable for being moved with a pallet fork, such as a pallet fork 301 of the vehicle 300. In FIG. 1, a pallet 201 is placed on the pallet fork 301. The pallet fork 301 can be seen better in FIG. 2 and FIG. 3.

(24) FIG. 2 depicts a similar situation as shown in FIG. 1, seen from above. FIG. 3 depicts the robotic picking assembly 100 with another perspective view.

(25) The picking assembly 100 has an arm 1, which can be extended and retracted along a substantially horizontal direction. As shown in FIG. 2 and FIG. 3, the arm 1 can extend a substantial distance into the pallet rack 200. At a free end 1a of the arm 1 there is mounted a gripping tool 20, which is configured to engage the item 203. When the gripping tool 20 has engaged and holds the item 203, the arm 1 is elevated and retracted to collect the item 203. The collected item is then placed on the pallet 201 carried on the pallet interface (pallet fork 301), and the picking assembly 100 can then pick another item 203 to be placed on the carried pallet.

(26) In the depicted, typical application of the assembly 100, it can move about between several rows of pallet racks 200, pick various items 203, and place such items on the pallet 201 which it carries with it.

(27) FIG. 4 and FIG. 5 depict a part of the picking assembly 100 in a situation where the arm 1 is extended, such as shown in FIG. 3. FIG. 6 shows the arm 1 in a retracted position.

(28) The arm 1 is supported in an arm support arrangement 8. As can be understood by the drawings in FIG. 4, FIG. 5, and FIG. 6, the arm 1 comprises a plurality of arm modules 2 that are connected to each other with a pivot means, here in the form of a hinge 4. As also appears from these drawings, the arm 1 can bend or curve in one direction only. Thus, in an unfolded, extended state, the unfolded portion of the arm 1 is substantially straight.

(29) The arm support arrangement 8 comprises an arm drive arrangement 7, which will be discussed in further detail below. The arm drive arrangement 7 is a motorized arrangement configured to move the arm 1 out towards the extended position (FIG. 5) and back into the retracted position (FIG. 6).

(30) As will also be discussed in more detail below, the arm support arrangement 8 is configured to store the arm 1 by moving it vertically upwards. A back end 1b of the arm 1 is pivotally fixed to an end unit 24 of the arm support arrangement 8. During extension and retraction out from and into the arm support arrangement 8, the shape of the arm part in the arm support arrangement 8 changes between the nearly O-shaped form shown in FIG. 5 and the upside-down U-shape shown in FIG. 6.

(31) The gripping tool 20 at the free end la of the arm 1 can be of any suitable type. For instance, it may be a suction device that is configured to lift items by means of vacuum. In other embodiments, the gripping tool 20 may be of another type, for instance using an electromagnet or a mechanic gripping device. As the skilled person will appreciate, there must be a link to the gripping tool 20, such as a vacuum hose or an electric cable, to operate it. This will be discussed below.

(32) Advantageously, the gripping tool 20 is configured to rotate about a vertical axis. In this manner, it will be able to position collected items 203 on the pallet 201 supported by the pallet fork 301 of the vehicle 300 in a desired orientation. Moreover, by having the gripping tool 20 able to rotate, it can be rotated to the mutual position between the gripping tool 20 and the item 203, which provides the best interface for lifting and holding the item 203. In some embodiments, the gripping tool is configured to rotate at least 90 degrees to either side from an initial base position.

(33) Indicated on FIG. 5 and FIG. 6 is an arm guide orifice 6, which defines the longitudinal position where the straight portion of the arm 1 leaves the arm support arrangement 8. Advantageously, the free portion of the arm 1, i.e. the straight portion of the arm that extends out of and beyond the arm support arrangement 8, can advantageously be at least as long as the corresponding longitudinal length of the arm support structure 8. More preferably, the free portion of the arm 1 can be more than twice the longitudinal length of the arm support arrangement.

(34) When in a fully extended position, the distance between the position of the gripping tool 20 and the position where the arm 1 enters the arm support arrangement 8, is advantageously at least 1.5 meters, preferably at least 1.6 meters. This means that when arranged adjacent a pallet rack 200, the robotic picking assembly 100 can reach and pick items 203 at about 1.6 meters into the rack. Such a situation is illustrated in FIG. 2 (although in this image, there is some distance between the arm support structure 8 and the face of the pallet rack 200).

(35) Reference is now made to FIG. 7, as well as to FIG. 6. In FIG. 7, a side panel of the arm support arrangement 8 has been removed for illustrational purpose.

(36) As can be seen in FIG. 7, the arm modules 2 are provided with a pitch rack 23 on their underside. When the arm 1 is in its straight configuration, the pitch rack 23 of the adjacent arm modules 2 together form a continuous pitch rack. The arm drive arrangement 7 comprises an arm drive motor 71 (FIG. 6) that drives a cogwheel 22 (FIG. 7). The cogwheel 22 is in engagement with the pitch racks 23 of the arm modules 2, thereby being able to move the arm 1 between the extended and retracted positions. When rotating the cogwheel 22 so that the arm 1 moves towards the retracted position, a portion of the arm 1 is automatically guided vertically upwards so that it takes the upside-down U-shape shown in FIG. 6. In alternative embodiments though, the portion of the arm stored in the arm support arrangement 8 could also be stored in a rolled-up configuration. That could, however, require more space in the horizontal direction.

(37) Instead of the cogwheel 22 engaging with a pitch rack 23, other means for moving the arm 1 can be used. For instance, a drive system based on friction can be used, such as a rubber wheel replacing the cogwheel and a flat surface replacing the pitch rack 23.

(38) Referring to FIG. 7 and FIG. 8, the arm modules 2 comprise guiding surfaces 13 at opposite lateral sides. In the shown embodiment, the guiding surfaces 13 are arranged at a lower portion of the arm modules 2. The arm support arrangement 8 comprises one or more pairs of lateral guide wheels 121 that engage the guiding surfaces 13. This provides lateral stability of the extended part of the arm 1. The lateral guide wheels 121 are configured to rotate freely about a vertical axis.

(39) In addition to the lateral guide wheels 121, there is arranged a lower vertical guide wheel 21a. The lower vertical guide wheel 21a supports the extended portion of the arm 1 from below. The lower vertical guide wheel 21a rotates about a horizontal axis, perpendicular to the extended portion of the arm 1.

(40) An upper vertical guide wheel 21b is arranged to keep the pitch racks 23 of the arm modules 2 in engagement with the cogwheel 22. Also, the upper vertical guide wheel 21b presents a counterforce against the arm 1 so that the arm is retained in its correct extending position.

(41) When the arm 1 is in an extended position, such as shown in FIG. 5, the vertically directed forces from the lower vertical guide wheel 21a and the upper vertical guide wheel 21b retain the arm in the correct vertical position. The lateral guide wheels 121 retain the arm in the correct lateral position.

(42) Advantageously the upper vertical guide wheel 21b is arranged directly vertically above the cogwheel 22 of the arm drive arrangement 7. This ensures a proper engagement between the cogwheel 22 and the pitch racks 23, even when a heavy item 203 is carried by the gripping tool 20.

(43) As the skilled person now will appreciate, the entire horizontal movement between the extended and retracted positions of the arm 1, can be performed with only one motor (i.e. the arm drive motor 71). Furthermore, even when in an extended position, no power is required to maintain the arm in the correct position, since the arm rests in its support in the arm support arrangement 8 (i.e. the lower and upper vertical guide wheels 21a, 21b in the shown embodiment).

(44) The adjacent arm modules 2 are linked to each other by means of a pivot means 4 (FIG. 8), which advantageously can be in the form of hinge bolts. As shown in FIG. 8, module rollers 32 are arranged in line with the pivot means 4. In the shown embodiment, the module rollers 32 are arranged at the end of the hinge bolts. In other embodiments, the module rollers 32 can be arranged elsewhere on the arm modules 2.

(45) As shown in FIG. 8, the module rollers 32 are received in roller grooves 33 arranged in the arm support arrangement 8. The roller groove 33 is a form of guiding means of the arm support arrangement 8, which contributes in aligning the arm modules 2 with each other. The roller grooves 33 also contribute in guiding the module rollers 2 towards the correct position during movement towards the extended or retracted position.

(46) During movement towards the retracted position, additional (not shown) roller grooves arranged in the arm support arrangement 8 can be provided to lift the arm modules 2 towards the curved shape rearwards of the cogwheel 22 and the upper vertical guide wheel 21b. A sliding abutment between the arm modules 2 and an arm track 25 on rear vertical portion of the arm support arrangement 8 may also contribute in guiding the stored portion of the arm towards its storage configuration. The engagement between the module rollers 32 and the roller groove 33 will be further discussed below, with reference to FIG. 17.

(47) The arm track 25, lateral guide wheels 121, lower vertical guide wheel 21a, and the upper vertical guide wheel 21b together form an arm guiding arrangement configured to guide the arm 1 correctly between the extended position and the retracted stored position. The roller groove 33 may also be a part of the arm guiding arrangement. This is discussed in further detail below, with reference to FIG. 17.

(48) While movement of the arm 1 towards the extended and the retracted positions has been discussed above, reference is now made to FIG. 9, for discussion of vertical movement and rotational movement of the arm 1.

(49) The robotic picking assembly 100 shown in FIG. 9 is arranged on a tower 30. The tower 30 is supported on a rotating base plate 34. The base plate 34 is provided with a circular toothed perimeter and is configured to rotate with respect to a bottom plate 31. A rotation motor 35 is fixed to the bottom plate 31, and provides rotation of the base plate 34, the tower 30, and thus the arm 1 upon activation and engagement with the toothed perimeter of the base plate 34. As the skilled person will appreciate, other means for rotation of the tower 30 may be appropriate. For instance, a belt drive can be arranged and driven by an electric actuator.

(50) At an upper portion of the tower 30, there is arranged a vertical motor 36, which is provided for vertical movement of the arm support arrangement 8 along the vertical extension of the tower 30. The vertical motor 36 is barely visible in FIG. 9 due to the arm 1 but can be seen more clearly in FIG. 3.

(51) The arm support arrangement 8 is configured to move vertically with respect to the tower 30 and is guided on a vertical guide rail 37. The mechanism for moving the arm support arrangement 8 is not discussed in detail herein, as the skilled person may choose among a variety of different solutions to obtain this movement. As an example, the vertical motor 36 may operate a chain connected to the arm support arrangement 8, to provide the vertical movement.

(52) It is now clear to the skilled person that the arm 1 can be moved vertically and it can be rotated. As can be seen in FIG. 3, the robot assembly 1 is provided with a pallet interface structure, making it suitable for being moved by a pallet-moving AGV having a pallet fork 301. In other embodiments, however, the robot assembly 100 according to the invention may be integrated as a part of an automated/autonomous robotic vehicle. In such embodiments, the robot assembly 100 and the vehicle can be optimized as one single assembly.

(53) As briefly mentioned above one needs to convey power to the gripping tool 20 to operate it. Moreover, to provide an automated, autonomous assembly, one may provide various types of sensors on the arm 1. Typically, such sensors may be arranged at the position of or in connection with the gripping tool 20. FIG. 10 depicts a cross section side view through the arm 1 and the arm support arrangement 8. An umbilical 38 is extended inside the arm 1, along an umbilical channel 26 provided in the arm. The umbilical may contain a vacuum hose (not shown), electrical cables, optical fibers etc., depending on the specific embodiment. Advantageously, by arranging the umbilical inside the arm 1 itself in this manner, it is less exposed for damage by becoming entangled with external parts.

(54) FIG. 11 and FIG. 12 depict one arm module 2 with perspective views. As appears from FIG. 11, the pivot means 4 comprises a hinge bolt 17 that is extended through two side walls 44 of the arm module 2. When in a hinged/connected state, the hinge bolt 17 extends through a pair of hinge apertures 40 arranged at the opposite end of the arm module 2. The hinge apertures 40 is one example of a front hinge structure 10, which for other embodiments may have another design.

(55) The mutual pivoting of two adjacent arm modules 2 takes place about a pivot axis. In the embodiment shown in FIG. 11 and FIG. 12, the pivot axis extends through the center of the hinge bolt 17.

(56) The arm modules 2 have a front portion 43 and a rear portion 42. The modules 2 have a generally box-like shape, with a box-like module body 3 with two side walls 44. The front portion 43 has a reduced size so that at least a part of it can be received between the side walls 44 at the rear portion 42. At a lower portion, the module body 3 has a mainly flat lower surface 12, to which the pitch rack 23 is fixed.

(57) To ensure that the arm 1 can curve only in one direction, a curve in the opposite direction is prevented by means of a pivot restriction means. In the shown embodiment, the pivot restriction means comprises a rear end surface 15 that is configured to abut against a front end surface 16 when in the straight (extended) configuration.

(58) The rear portion 42 of the arm module 2 is provided with a stabilizing groove 28, which is configured to receive a stabilizing protrusion 27 at the opposite front portion 43.

(59) FIG. 13 depicts an alternative embodiment of the picking assembly 100. In this embodiment, the tower 30 comprises two vertical beams 30a and the arm support arrangement 8 is positioned between these vertical beams. The location where the extended portion of the arm 1 exits out from the arm support arrangement 8, is termed an arm guide orifice 6.

(60) FIG. 14 and FIG. 15 depict an alternative embodiment of the arm module 2. In this embodiment, there are arranged side grooves 29 on each opposite side of the side walls 44 of the arm module 2. The side grooves 29 may engage with guiding wheels supported in the arm support arrangement 8. By having side grooves 29 with inclined surfaces, such guiding wheels may simultaneously support the arm 1 laterally and vertically.

(61) The pivot restriction means can comprise a rear abutment surface 18 and a mating front abutment surface 19 positioned below the pivot means at the lower part of respective end surfaces 15, 16 of the module body 3 of two consecutive modules, wherein the abutment surfaces 18, 19 abuts when the centerline of the two consecutive modules are parallel. In an alternative embodiment, the respective end surfaces, as indicated in FIG. 11 and FIG. 12, can be the abutting surfaces that prevents excessive pivoting motion beyond the straight shape of the extended arm 1.

(62) Advantageously, in an embodiment of the second aspect of the invention, the arm drive 7 is a cogwheel 22 fastened to the guide orifice 6 and powered by a motor and a pitch rack 23 fastened to the lower side 12 of the modules 2.

(63) The respective end faces of each module can advantageously comprise a protrusion 27 and a mating groove 29, for improvement of sideway stability of the arm.

(64) An end unit 24 can be arranged in the arm support arrangement 8, which holds the end of the arm 1 in a fixed position, hinged or non-hinged, directing the stored part of the arm vertically away from the guide orifice. Furthermore, the arm track 25 can be arranged, guiding the stored part of the arm towards the guide orifice 6 after the stored part of the arm has described a 180 degree turn.

(65) An umbilical channel 26 parallel to the longitudinal centerline of each module can be provided.

(66) Advantageously, the angular range of movement between any two consecutive arm modules 2 can be at least 30 degrees from an initial straight position.

(67) FIG. 16 depicts two adjacent modules 2 of the arm 1, which are curved to their maximum extent. To restrict excessive curving, beyond the position shown in FIG. 16, a curve restriction means is provided. In the shown embodiment, the curve restriction means is in the form of two abutting curve restriction faces 45, 46. As appears from FIG. 16, the two curve restriction faces 45, 46 abut so that a further curving or pivoting movement is prevented.

(68) FIG. 17 depicts a cross section, principle view showing the module rollers 32 in engagement with the roller groove 33. For illustrational purpose, the modules 2 are not shown, but rather only their module rollers 32, which are attached to the modules, as shown for instance in FIG. 8.

(69) In this embodiment, the arm guiding arrangement of the arm support arrangement 8 comprises the roller groove 33. As appears from FIG. 17, the roller groove 33 has a horizontal portion 33a and a curved portion 33b. The curved portion 33b curves upwards at a rear end of the horizontal portion 33a. When the arm 1 is retracted towards its storage configuration (as shown in FIG. 6), the curved portion 33b will force the modules 2 upwards and thus provide adjacent modules to pivot with respect to each other. The horizontal portion 33a is straight, and thus guides a straight portion of the arm 1.

(70) The horizontal portion 33a of the roller groove 33 can in some embodiments provide sufficient support to the extended portion of the arm 1, so that the lower vertical guide wheel 21a (FIG. 7) can be omitted from the arm support arrangement 8. By omitting the lower vertical guide wheel 21a from the arm guiding arrangement, the arm 1 can be pulled a further distance into the arm storage arrangement 8. This is because the lower vertical guide wheel 21a will not collide with the gripping tool 20. In this way, a more compact robotic picking assembly 100 can be provided, with respect to horizontal extension when in the retracted storage mode.

(71) In some embodiments according to the present invention, the length of the horizontal portion 33a of the roller groove 33 has a length that is less than 2.5 module lengths. Advantageously, the length of the horizontal portion is less than 3.5 module lengths. The module length is herein defined as the length between two adjacent pivot axes of two adjacent, connected arm modules 2 of the arm 1.

(72) FIG. 18 depicts an alternative solution for rotation of the tower 30, which was shown in FIG. 9. While the embodiment shown in FIG. 9 has a base plate 34 with a toothed circular perimeter, the embodiment shown in FIG. 18 has a base plate ring 34a where the teeth are facing inwards from an internal circular face. A toothed rotation drive wheel 35a, which is driven by a rotation motor 35, engages the teeth of the base plate ring 34a. The tower 30 (not shown) is attached to the base plate drive ring 34a, and thus rotates upon actuation of the rotation motor 35.

(73) The example discussed above relates to an embodiment where the arm 1 is configured to curve in an upward direction. In other embodiments, the arm 1 can be supported in such way that it curves in a sideway direction. In such embodiments, it will curve and extend along a substantially horizontal plane. By arranging the arm support arrangement 8 in such a manner, i.e. to curve the arm along a horizontal plane, the assembly 100 will need less space vertically above it. Hence, it may then be suited to work close to a ceiling inside a building.

(74) FIG. 19, FIG. 20 and FIG. 21 depict an alternative embodiment a vertical movement arrangement, configured to move the arm support arrangement 8 vertically. As with the embodiments discussed above, there is arranged tower 30 that supports the arm support arrangement 8 (not shown in these figures). Advantageously, the tower 30 can be mounted on a rotating base plate 34, as in the previous embodiments.

(75) In this embodiment, the tower 30 comprises a plurality of tower modules 30b that are telescopically movable with respect to each other. As appears from the drawings, in the situation shown in FIG. 19 and in FIG. 20, the telescopic tower 30 is in the vertically extended position. The arm support 8 is omitted in these drawings for simplicity but would typically be fixed to the uppermost tower module 30b.

(76) FIG. 21 is a cross section side view illustrating the tower 30 in the vertically lower position. To move the uppermost tower module 30b vertically, a vertical drive arrangement 60 is arranged. In this embodiment, the vertical drive arrangement 60 can be a rigid chain actuator. The rigid chain actuator 60 comprises a chain drive wheel 61 that engages with a chain 63. The chain 63 can take a straight and rigid configuration and is fixed to the uppermost tower module 30b. By rotating the chain drive wheel 61, typically with a vertical motor 36, the tower 30 can thus be extended and retracted in the vertical direction.

(77) An advantage of this type of tower, is that the chain drive wheel 61 and the chain 63 is enclosed inside the tower 30 itself. In this way, these parts are less exposed to impurities and personnel will be less exposed to hazard by the these moving parts.

(78) Advantageously, the horizontal cross section of the tower modules 30b exhibits a rectangular shape. This improves stability of the tower 30.

(79) An alternative definition of the present invention is presented in the following. According to a second aspect of the invention, there is provided a modular extendable arm 1 comprising a plurality of identical arm modules 2 linked together in a chain, wherein each module comprises a module body 3 with mainly flat upper 11, lower 12 and side surfaces 13, 14 being parallel with the central axis of the module. Pivot means 4 between each two consecutive modules provides relative angular movement in an upward direction from an initial horizontal position. Furthermore, pivot restriction means 18, 19 between each two consecutive modules preventing relative angular movement in a downward direction from an initial horizontal position. An arm guide orifice 6 holds the arm 1 in a mainly horizontal position. An arm drive 7 can move the arm in and out in the guide orifice 6. The modular extendable arm further comprises an arm storage system 8 for the part of the arm which is not extended past the guide orifice.

(80) According to an embodiment of the second aspect of the invention, the pivot means comprises a rear hinge structure 9 and a mating front hinge structure 10 located at respective rear 15 and front 16 end surfaces of the module body with a hinge bolt 17 going there through, wherein the hinge structures are at the same distance from the upper surface.