GB2247601A

GB2247601A - Cutting apparatus and methods for use in micropropagation.

Info

Publication number: GB2247601A
Application number: GB9116138A
Authority: GB
Inventors: William Peter Billington; Peter Michael Grundon
Original assignee: National Research Development Corp UK
Current assignee: National Research Development Corp UK
Priority date: 1990-07-25
Filing date: 1991-07-25
Publication date: 1992-03-11
Also published as: GB9016323D0; GB9116138D0; AU8321991A; WO1992001369A1; EP0540620A1

Abstract

A robotic end effector (48) for use in micropropagation comprises six resilient gripping elements (11) which are splayed apart by a transverse plate (13) carrying a blade (15). The end effector is placed over a plant to be divided, with the distal ends (14) encompassing the plant. As the blade (15) is lowered, the plate (13) allows the distal ends (14) to move together and grip the plant which is then cut by the blade (15). The entire end effector is lifted and moved to a planting location. A fork (17) is propelled downwardly until the fingers (18 and 19) of the fork enter the region (16) and dislodge half of the cut plant portion. At a further planting location, the gripping elements (11) are rotated through (180), and the fork (17) is again lowered to dislodge the second cut portion of plant.

Description

CUTTING AND/OR MANOEWRING APPARATUS AND METHODS The present invention relates to apparatus for and methods of cutting and/or manoeuvring objects, and relates in particular, but not exclusively, to apparatus and methods for use in micropropagation.

Micropropagation of plants involves the use of the techniques of plant tissue culture and the application of these to the propagation of plants. At its simplest, micropropagation consists initially of surface sterilising and excising small pieces of actively growing tissue, normally shoot tips or nodes cut from the stems of plants.

Then, under aseptic conditions, the pieces of tissue are transferred to a nutrient medium which supports plant growth. The plant material will finally develop into entire plantlets. These plantlets must then be weaned from the axenic conditions in which they have existed within the laboratory into viable, rooted plants capable of survival in conventional horticultural or agricultural environments.

Normally the step of cutting a plantlet into small pieces, for regrowth (the multiplication stage) is repeated several times before a batch of plantlets is grown to viable plants.

The technique is labour-intensive, and four of the particularly important operations which are repeated frequently are (i) removing a plant from a container in which it is growing, (ii) cutting a required portion of plant tissue from the donor plant, (iii) transferring the required piece of plant material, to a soft, nutrient medium in which it is to be grown, and (iv) placing the plant portion in the medium in a position suitable for growth. As performed at present, the cutting operation normally consists of an operator holding the plant material by forceps on a sterilised card by one hand, and cutting the required portion of the plant by strokes of a scalpel, by the other hand. The cut portion is then transferred by forceps to the soft nutrient medium, which is in the nature of a gel, and the cutting is then placed upright in the soft nutrient medium.The positioning is normally carried out by the use of forceps.

In the micropropagation of some species, for example syngoniums, a callus of plant material is grown and small shoots grow from it. At intervals during its growth it is divided into several more pieces such that each retains one or more strong shoots. The larger leaves on the longest shoots are cut off to encourage the formation of more shoots. After a number of cycles of division and replanting, the many pieces of callus obtained are allowed to grow into normal plants.

The high cost of these labour-intensive operations has meant that micropropagation techniques have been limited to plant species which attract an adequate premium for greater uniformity or vigour, or are difficult or impossible to propagate from seed or cuttings. It is an object of the present invention to provide apparatus and methods for effecting cutting operations involved in micropropagation suitable for automatic or semi-automatic systems using robotic apparatus. This will allow the benefits of micropropagation to be utilised in the growth of more plant species where it is at present prohibited by the costs involved.

According to the present invention in a first aspect there is provided apparatus for cutting an object comprising a plurality of elongate gripping elements extending in the same general direction with the distal ends thereof encompassing a region for an"object to be cut; control-means-for controlling movement of-the distal ends of the elements towards each other to grip an object to be cut; and cutting means operatively linked to the control means and operable in the said region encompassed by the distal ends of the gripping elements to divide an object gripped by the distal ends of the elements, into divided parts which remain gripped by the gripping elements.

Preferably the control means is moveable longitudinally of the elongate elements and cooperates with the elements to draw the elements together and/or force the elements apart during longitudinal movements of the control member, and also preferably the cutting means is moveable longitudinally of the elongate elements towards the distal ends thereof to divide an object encompassed by the distal ends of the elements.

In a preferred form the gripping elements are spaced from and arranged regularly around a longitudinal axis of the apparatus, and the control means and cutting means are both arranged to move along the longitudinal axis during operation.

In one preferred form of the invention, the control means is moveable longitudinally of the elongate elements and is cooperatively linked with the elements to force the elements apart during longitudinal movement of the control means away from the distal ends of the elements.

Conveniently the distal ends of the gripping elements are spring biased towards each other and the gripping of an object is effected by the spring biassing of the gripping elements. In one form, the control means comprises a control member which extends inside the assembly of elongate gripping elements and has bearing surfaces which exert an outward force on the elongate elements during operation of the device.

In accordance with one preferred feature according to this aspect of the invention, the elongate elements include a portion along which the elements diverge from each other and a portion along which the elements are substantially parallel to each other, the arrangement being such that during at least part of the period of operation when the cutting means is cutting the object, the control means is associated with the parallel portions of the elements and no movement inwardly of the distal ends is brought about.

In an alternative form of the invention, it may be arranged that the control means is moveable longitudinally of the elongate elements and is cooperatively linked with the elements to draw the elements together during longitudinal movement of the control means towards the distal ends of the elements. Conveniently, the distal ends of the gripping elements are spring biassed apart and the gripping of an object is effected by the control means drawing the elements together during longitudinal movement of the control means towards the distal ends of the elements. In one convenient form, the control means comprises a control member which extends around the outside of the assembly of elongate gripping elements and has bearing surfaces which exert an inward force on the elongate elements during operation of the device.

In accordance with a preferred general feature of the invention, the control means is arranged to commence the movement of the distal ends of the gripping elements towards each other before the cutting means operates in the said region, and an object to be cut is centred by the elements relative to the cutting means before being cut.

The apparatus has particular utility where the object to ba cut- comprises a plantlet to be cut during the mu1tiplication -stage of micropropagation.

In another aspect, the gripping elements according to the invention may find application without the use of a cutting means, for example for transferring whole plants to a root initiation medium.

In a preferred form the cutting means may be coupled to the second member and is moveable therewith,preferably being coupled in such a manner that during the said movement of second member, the elements are drawn together before the cutting means operates in the region encompassed by the distal ends of the gripping elements. Conveniently the distal ends of the elements are arranged symmetrically around the said region, for example defining a circle, and the cutting means is positioned symmetrically relative to the said region.

Conveniently, the cutting means comprises one or more blades extending transversely in the region encompassed by the gripping elements, for dividing an object into two or more parts. Preferably the blade or blades are arranged to extend transversely beyond the said region encompassed by the gripping elements. Such an arrangement ensures complete cutting of the object where, for example, the object is likely to extend beyond the region encompassed by the distal ends of the gripping element, for example where the object is a plantlet during micropropagation. Also preferably the cutting means is arranged to extend longitudinally beyond the distal ends of the gripping elements, when at its most distal position. Such an arrangement facilitates the dislodgment of cut portions of the object from the gripping means.For example, where the cutting means comprises a blade, the blade may extend transversely between gripping elements, beyond the said region, and the blade may be arranged to protrude downwardly beyond the distal tips of the elements, when at its most distal position.

In accordance with a further, preferred, feature of the invention, there may be provided means for dislodging from the gripping elements a selected cut portion of an object held by the elements. Conveniently the dislodging means comprises an elongate pushing member positioned so as to be inclined to the general direction of the gripping elements and directed towards the region encompassed by the distal ends of the elements, the pushing member being moveable longitudinally so as to protrude between gripping elements into the region encompassed by the tips of the elements. Preferably the dislodging means comprises an elongate pushing member having two fingers adapted to protrude between gripping elements into the region encompassed by the ends of the elements.In one preferred arrangement the assembly of gripping elements is rotatable relative to the dislodging means so as to allow successive dislodging of selected portions of the cut object by successive rotation of the gripping elements and operation of the dislodging means.

Apparatus according to the invention finds particular application in robotic handling of plant material during micropropagation. Preferably the apparatus includes drive means for moving the components through a sequence of movements in which, the gripping elements are moved towards a first work station for a plantlet to be cut during micro-propagation; the gripping elements move together and the cutting means are operated; and the gripping elements are moved to a second work station for a container of nutrient medium for cut portions of the plantlet.

Preferably the drive means is arranged to include in the sequence of movements, the operation of the dislodging means to (iis:1Odg a first cut portion of plantlet onto the nutrient medium;:; translational movement of the gripping elements-- to-' a;- fflrther location on the nutrient medium; rotational movement of the gripping elements; and further operation of the dislodging means to dislodge a further portion of plantlet onto the nutrient medium.

In general, where features of the invention have been set out with regard to an apparatus, these features may also be provided with regard to a method, and vice versa.

In particular there may be provided in accordance with this aspect of the invention, a method of cutting an object comprising the steps of positioning around the object the distal ends of a plurality of elongate gripping elements which extend longitudinally in the same general direction; moving the distal ends of the elements towards each other to grip an object to be cut; and cutting the object by cutting means operating in the said region encompassed by the distal ends of the gripping elements.

It is preferred, in this method, that the gripping elements are moved towards each other before the cutting means operates in the said region, whereby an object to be cut is centred by the elements relative to the cutting means before being cut. Preferably the method includes operating the cutting means by moving the cutting means longitudinally of the elements towards the distal ends thereof, and preferably includes the steps of dislodging successively from the gripping elements selected cut portions of the object held by the elements after cutting.

Preferably the method includes the step of rotating the gripping elements relative to the dislodging means between successive dislodging of selected portions of the cut object.

In accordance with a further aspect, the invention relates to apparatus for, and a method of, manoeuvring an object without necessarily cutting the object.

In accordance with the invention in this aspect, there may be provided apparatus for manoeuvring an object comprising a plurality of elongate gripping elements extending from a first member in the same general direction with the distal ends thereof encompassing a region for an object to be gripped; and a second member moveable longitudinally of the elements towards the distal ends thereof and cooperating with the elements to effect movement of the elements towards each other at the distal ends thereof during the said movement so as to grip an object encompassed by the distal ends of the elements.

There may further be provided, in accordance with the invention in this aspect, a method of manoeuvring plant material during micropropagation comprising the steps of positioning around the plant material the distal ends of a plurality of elongate gripping elements which extend longitudinally in the same general direction; and effecting movement of the distal ends of the elements towards each other to grip the plant material by moving longitudinally of the elements control means which cooperates with the elements.

The invention also relates, in a further aspect to a general system of cutting and transporting plant material during micropropagation.

According to the invention in this aspect, there is provided a method of cutting and transporting plant material during micropropagation comprising the steps of presenting at a work station a container containing plantlets growing in a nutrient medium; gripping a plantlet bX robotic gripping means; dividing the plantlet into two or mor'portions; byta blade moved downwardly onto the p1antlet;'-- lifting; the cut plantlet by thegripping means; moving - the -cut plantlet to a second work station over a fresh nutrient medium; and dislodging a part of the cut plantlet onto the fresh nutrient medium.Preferably the method includes previously cutting an upper portion of the container free from a lower portion which contains the nutrient medium supporting the plantlet; and removing the said upper portion of the container to provide access to the plantlets.

In accordance with a yet further aspect of the invention, there is provided a method of cutting and transporting plant material during micropropagation comprising the steps of presenting at a work station a container containing plantlets growing in a nutrient medium; cutting an upper portion of the container free from a lower portion which contains the nutrient medium supporting the plantlets; removing the said upper portion of the container to provide access to the plantlets; dividing a plantlet into two or more portions; and transporting to a fresh nutrient medium the cut portions of the plantlet.

One preferred feature of these methods, is that the method includes the step of cutting unwanted upper portions of the plantlets from base portions of the plantlets before dividing the plantlets, and removing the unwanted upper portions of the plantlets to provide access to the base portions of the plantlets. Conveniently the step of cutting the upper portions of the plantlets is effected by a pair of adjacent rotary cutting discs rotating about vertical axes, and the method includes removing the said upper portion of the container and/or the upper portions of the plantlets, by forced air flow.

Preferably the method according to these aspects of the invention includes gripping the plantlet by a plurality of gripping elements which encompass the plantlet and which are moved inwardly toward the plantlet to centre the plantlet below a cutting means for cutting the plantlet.

Preferably the method includes depositing successive portions of the cut plantlet at a series of planting locations over the nutrient medium.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure la is a perspective side view of apparatus embodying the invention for cutting and/or manoeuvring a plantlet during micropropagation; Figure ib is a perspective side view of the apparatus of Figure la, taken at a later stage in operation of the apparatus, when gripping elements of the embodiment have moved together to grip a plantlet and blade of the apparatus has been lowered to cut the plantlet; Figure lc is a perspective view of the apparatus of Figure ib, taken in the direction of the arrow B in Figure 1b but with the blade and gripping elements of the apparatus rotated through 90 ;; Figure id is a further perspective side view of the apparatus of Figure ic taken at a final stage in the use of the apparatus, when a pushing member has been extended to dislodge a portion of cut plant material from the gripping elements of the apparatus; Figure 2a is a cross-section of the apparatus shown: in the preceding figures, and corresponds generally to the stage of operation shown in Figure la; Figure 2b is a cross-section of the apparatus shown in Figure 2a, but at a stage of operation corresponding to that shown in Figure ib, and Figure 2c is a section along the lines A-A in Figure 2b; Figure 3a is a perspective side view of a modification of the apparatus shown in the preceding figures, embodying the invention for cutting and/or manoeuvring a plantlet during micropropagation; Figure 3b is a perspective view of the apparatus of the Firuge 3a, taken in the direction of the arrow B in Figure 3a;; Figure 3c is a further side perspective view of the apparatus of Figure 3a, taken at a later stage in operation of the apparatus, when gripping elements of the embodiment have been drawn together to grip a plantlet and a blade of the apparatus has been lowered; Figure 3d is a further side view of the apparatus of Figure 3c, taken at final stage in the use of the apparatus, when a pushing member has been extended to dislodge a portion of cut plant material from the gripping elements of the apparatus; Figure 3e is a cross-section of the apparatus of Figure 3a, taken generally in the plane of the paper of Figure 3a; Figure 4 is a diagrammatic plan view illustrating schematically a method of cutting and transporting plant material during micropropagation embodying the invention;; Figure 5 is a perspective view of the general lay out of part of one form of the apparatus shown in Figure 4; Figure 6 shows part of the apparatus of Figure 5, at the location indicated at L2 in Figure 4, relating to the removal of an upper portion of a container for plantlets; Figure 7 is a side perspective view of the same apparatus part as shown in Figure 6, but after the removal of the upper portion of the container; Figure 8 shows a further portion of the apparatus of Figure 5, and illustrates plant material at location L4 in Figure 4, after removal of upper parts of the foliage of the plants.

Referring firstly to Figures la to 2c, there is shown apparatus for cutting plant material, for example the callus base of a syngonium, during micropropagation. The apparatus is conveniently used in an automatic robotic system to be described hereinafter with reference to Figures 4 to 8, but may also be used in semi-automated systems.

As shown in Figures la, and 2a the apparatus comprises mainly six resilient elongate gripping elements 11, for example resilient rods of spring steel, extending in the same general direction downwardly from a first member comprising a rotatable carriage 12. As shown in Figure 2a, the rods 11 are biassed inwardly due to their shape and their setting in the carriage 12, and the rods 11 are splayed!outwardly by the effect of a second member comprising a transverse plate 13. The plate 13 is moveable uwardiy--and downwardly (as will be explained hereinafter) alLowi-ng the rods Il to move inwardly and outwardly between a splayed apart-position shown in Figure 2a; and a further position shown in: Figure 2b, where the rods.have moved more closely towards each other at the distal ends thereof.

Thus, in the first position shown in Figures la and 2a, the transverse plate 13 is in the raised position, forcing the rods 11 apart.

The lower ends of the rods 11 have a dog-leg shape whereby the distal ends 14 of the rods are shaped inwardly relative to the main, splayed out, length llA of the rod 11 where it cooperates with the transverse plate 13. The rods 11 are shaped so that, when the rods 11 are in the closed position shown in Figure 2b, the distal ends 14 are substantially parallel to each other at llc. Also at this stage, lower main portions llB of the rods 11 are also substantially parallel to each other.

The transverse plate 13 carries a blade 15 which is mounted to move with the plate 13, in order to cut plant material located in a region 16 encompassed by the distal ends 14 of the rods 11. Positioned to one side of the rods 11 is a pushing member formed by a fork 17 having two flexible fingers 18 and 19 formed by stiff coil springs 18A and 19A with rounded end pieces 18B and 19B inserted in the coil springs. The fork 17 is moveable longitudinally towards the distal ends 14 of the rods 11, to dislodge cut portions of plant as will be described in more detail hereinafter. The gripping elements 11, the plate 13, and the pushing member 17, are all mounted on a main housing 20 which is positioned vertically above the plant material to be cut.

The apparatus will now be described in more detail, followed by a description of the method of operation. The rotating carriage 12 is mounted in upper and lower bearings 21 and 22 in the fixed main housing 20, and is coupled to a stepper motor 23 (shown diagrammatically) by a toothed belt 24 passing about a pulley 25 fixed relative to the carriage 12. The rods 11 may be formed of spring steel piano wire of 16 gauge, for example having a 1.5mm diameter and 9cm free length. The distal tips 14 may be splayed out to encompass a circle of diameter approximately 3.5cm.

Passing through the centre of the carriage 12 is a piston rod 26 which extends downwardly to be fixedly secured to the transverse plate 13 and blade 15, and extends upwardly through a length adjustment device 27 to a pneumatic cylinder 28 mounted on top of the main housing 20. The piston rod 26 is an easy sliding fit in the rotating carriage 12, and may be moved upwardly and downwardly by the pneumatic cylinder 28. The sections of Figures 2b and 2c show that the main piston rod 26 may conveniently include a pair of flats 26A, which cooperate with guides 26B which are fixed relative to the rotating carriage 12.

These flats 26A ensure positive orientation of the cutter blade 15 relative to the gripper rods 11.

The pushing member comprising the fork 17 extends into a further pneumatic cylinder 29, mounted on a side arm 30 extending from the main housing 20. The fork 17 is positioned so as to be inclined to the general direction of the gripping elements, which general direction is indicated by the main longitudinal axis 31 of the assembly, shown in Figure 2a. The fork 17 is directed towards the region 16 encompassed by the distal ends 14 of the elements 11, and is moveable longitudinally so as to protrude between rods 14 into the region encompassed by the tips 14 of the rods 11. The piston of the pneumatic cylinder 28 is made to be non-rotatable to ensure correct orientation of the ejector fork 17 relative to the gripping rods 11.

The operation of the apparatus will noSwzbe-described When-installed' in an automatic micropropagati'on\system, the entire assembly shown in Figures la to 2c is mounted' as a robotic end effector (indicated generally at 48) and is moveable downwardly over a plantlet to be divided into two.

Firstly the apparatus is arranged as shown in Figure la with the fork 17 and plate 13 withdrawn upwardly, and the rods 11 splayed outwardly. The entire assembly is lowered downwardly over the plant to be cut until the plant is positioned within the region 16. The pneumatic cylinder 28 is then activated to move the blade 15 downwardly towards the plant. The first effect of this movement is to allow the distal ends 14 of the rods 11 to move inwardly toward the plant, producing a centring effect in which the plant is centred beneath the blade 15. Further movement brings the blade 15 into contact with the plant and the blade 15 is moved downwardly to divide the plant in two until the blade 15 rests against the bottom of the container in which the plants are growing. This stage is shown in Figure lb.

At this stage the plant is divided in two and gripped firmly by the elements 11. The entire assembly is then raised and moved to a second work station where fresh nutrient medium is available for the plant material and the assembly is lowered until the bottom of the fingers 11 are about at the level of the nutrient medium provided, eg.

such that the ends 14 are spaced from the bottom of the container for the plantlets by say 5mm. During the transfer, the carriage 12 is rotated to bring the fork 17 to the orientation shown in Figure lc with the fingers 18 and 19 spaced apart across the blade 15. The ejector pneumatic cylinder 29 is then operated to move the fork 17 downwardly so that the two fingers 18 and 19 penetrate into the region 16 between the distal ends 14, and by so doing dislodge half the cut plantlet and push it downwardly into the nutrient medium. This stage is shown in Figure ld.

The use of two fingers 18 and 19 is preferably to a single pushing member, since a single pushing member may tip the cut half plantlet to one side, rather than firmly planting the half plantlet into the nutrient material. The fork 17 is arranged to act over as large an area as possible of the portion of plantlet to be dislodged.

The next step (not shown in the Figures) is that the entire assembly is raised; the fork 17 is withdrawn upwardly; the carriage 12 is rotated through a 180 by the stepping motor 23; and the entire assembly is again lowered to the level of the nutrient medium, after translational movement to a fresh planting region. The ejector cylinder 29 is then activated to lower the fork 17, to dislodge the second half of the cut plantlet and to plant it in the nutrient material.

The assembly is then raised, the fork 17 withdrawn, and the blade 15 raised to prepare the assembly for placing over a further plant to be cut. Normally, the components which contact the plants are sterilised between each set of plants to be cut, for example after handling, say 20 plants. The sterilisation may be carried out by a gas flame, or by electrical heating, or by dipping in hydrogen peroxide.

The embodiment shown has a number of advantages. The contraction of the distal tips 14 of the rods 11 firmly grasp the plantlet during and after cutting, so that the location of the cut portions are known relative to the robotic end effector, and therefore can be dislodged and planted with certainty as to the positioning of the cut portions. The gripping by the elements 11 is effected by the inward bias of the elements themselves. The elements are shaped and set in the carriage 12, in such a manner that even in the closed position of Figure 2b,- the elements 11 are still biassed inwardly by an amount sufficient to grasp the plant. Once the plant has beenrlocated and centred below the blade 15, the robotic system has a certain orientation knowledge of the cut portions.The blade 15 extends transversely beyond the edges of the region 16, to ensure complete cutting of the callus. The blade 15 projects beyond the end of the distal tips 14, to give good release of the cut portion by the fork 17 forcing the cut portion off the blade 15.

In modifications, the blade 15 may be shaped as three symmetrically placed blades extending outwardly in the region 16 from the central axis 31. Such an arrangement allows the plantlet to be divided into three. Fewer or more rods 14 may be provided, for example in the range four to nine rods, depending on the plant concerned and the shape of the blade 15. In another modification, the roots may be trimmed from the plantlet after it has been cut and lifted by the apparatus. For example the roots may be trimmed by a rotating cylindrical knife.

The cutting apparatus is normally suitable only for the multiplication stage of micropropagation, where it does not matter if some stem portions of the plant are damaged during division. The final stage of division in micropropagation is preferably carried out by another method, so that the plantlet is left with stems to grow into the final plant for transplanting.

Figures 3a, to 3e show a modification of the apparatus shown in the preceding Figures. In the description of Figures 3a to 3e components which correspond to components in the preceding figures will be indicated by like reference numerals, and the description of the preceding figures shall be taken to apply, where appropriate, to Figures 3a to 3e.

Figures 3a to 3d shown stages of operation of the modified apparatus, and correspond approximately (but not exactly) to the Figures la to ld, showing the previous embodiment. Figure 3e is a cross section of the modified apparatus and corresponds generally to the cross section of Figure 2b, in connection with the previous embodiment.

The main modification of the second embodiment, is that the rods 11 are straight rods, and are neutrally set, or biassed outwardly, rather than being biassed inwardly as in the first embodiment. The transverse plate 13 of the second embodiment shown in Figures 3a to 3e, extends outwardly beyond the rods 11, and the rods 11 pass through a series of apertures 9 in the transverse plate 13, as shown for example in Figures 3c, 3d and 3e. This arrangement leads to a slightly different operation of the transverse plate 13. When the transverse plate 13 is raised to the position shown in Figures 3a and 3b, the rods 11 are splayed out by the plate 13 (or allowed to move outwardly under their own spring bias).When the transverse plate 13 is moved downwardly, to the position shown in Figures 3c, 3d and 3e, the transverse plate 13 draws the splayed rods towards each other by the effect of the outer edges of the apertures 9. Thus in the second embodiment, the rods 11 are positively opened to the splayed position by raising the transverse plate 13, and are positively drawn together, by lowering the transverse plate 13. In contrast, in the first embodiment of Figures 1 to 2c, the rods 11 are positively pushed outwardly by the transverse plate 13, when it is raised, but the rods 11 move together only by their own spring bias, when the plate 13 is lowered. In the first embodiment, the plate 13 does not positively draw the rods 11 together.

In the first embodiment of-Figures 1 to 2c, the rods 11 must be biased inwardly by their shape and setting. In the second embodiment of Figures 3a to 3e, the rods may be biased inwardly or outwardly, or may be set. to a neutral position between the splayed in and splayed out positions, since the movement is positively directed by the aperture plate 13. In a further modification (not shown) the rods 11 may be biased outwardly, and may be drawn together by a ring extending around the outside of the rods 11. Raising of the ring will then allow the rods 11 to splay apart by means of their own resilience.

The advantage of the second embodiment of Figures 3a to 3e, is that the objects to be cut are positively gripped by the positive effect of the lowering the transverse plate 13. On the other hand, it often occurs that the plantlets to be gripped are of varying sizes, and may be damaged by a too positive grip. Therefore the first embodiment of Figures la to 2c is generally preferred in micropropagation because it allows different sizes of plantlet to be gripped move gently. If a large plantlet is gripped, the rods 11 may remain splayed out slightly after gripping and centering the plant. As the plate 13 descends, the rods 11 may move inwardly until a firm grip has been established, and the blade may then continue to descend, without further movement inward of the rods 11.Conveniently, the rods 11 of the first embodiment can be spring biassed inwardly to a much smaller diameter than the second embodiment, for example to a diameter of say 2cm. No damage to the plant will occur if a larger plantlet is gripped, since the rods 11 will merely not fully close into the smallest diameter possible. It is to be appreciated that the second embodiment may have advantages if heavier objects are to be cut, particularly if they are uniform in size.

In both the embodiments of Figures la to Figure 2c, and Figures 3a, to 3e, it is an important preferred feature that the tool is rotated, before gripping the plant, to a selected orientation, in order to operate the cutter blade 15 along a preferred orientation. The base region of the plantlet, for example callus material, can be more reliably cut into its component parts without loss of fragments of material if the cutter blade 15 is aligned, relative to the base region to be cut, so as to part the base region at the boundary of dominant portions of the base region.

Another advantage of both embodiments is that the dislodging fingers 18 and 19 of the fork 17 are flexible, so that the rounded tips 18B and 19B wipe the blade 15 when the fork is moved inwardly and downwardly into the region 16. The fingers 18 and 19 not only interact with the plant material to dislodge it, but also exert a wiping action on the blade 15.

A particular advantage arises in the first embodiment shown in Figures 1 to 2c, because of the shape of the rods 11. An important feature of the invention is the simultaneous, or near simultaneous, action of gripping and cutting the plant material. However the shaping of the rods in the first embodiment means that the gripping and centering action occurs before the cutting action.

Referring to Figures la and Ib, it will be seen that as the transverse plate 13 descends, and cooperates with the upper portions 1lA of the rods 11, the distal ends 14 move progressively closer together under the action of the inward biasing. However as the transverse plate 13 reaches the lower portions llB of the rods 11, the rods have moved inwardly to a position where the portions llB are substantially parallel to each other, as shown in Figure 2b. Thus for the final downward movement of the blade 15, the plant is not moved by any further inward movement of the distal ends 14. The plantlet is merely held as the pLate 13 moves downwardly along the parallel portions 11B of the--rods:---li: There is normally no movbment inwardly of the tips 14, while the transverse plate 13 is moving in contact with the parallel portions llB of the-rods 11.

It is also to be noted that the tool which has been shown and described may be used without the use of the cutting blade 15, for example for transferring whole plants to a root initiation medium. In such a use, the blade 15 would be omitted from the apparatus.

There will now be described with reference to Figures 4 to 8 a general system for automatic micropropagation, which may utilise the cutting apparatus described above, but which embodies aspects of the invention independently of the cutting apparatus.

The main parts of the apparatus are shown in Figures 4 and 5, and consist of a stacking assembly 40 positioned over a conveyor belt 41, for handling containers 42 of plantlets 43 during micropropagation. The containers 42 are stacked in the stacker 40 and dispensed one at a time onto the conveyor 41. The conveyor carries a suction pad (not shown) onto which a container 42 is placed, so that the container is held firmly in place on the conveyor. Thus at location L1 in Figure 4, a container 42 of plantlets is deposited from the stacker 40 onto the conveyor and is conveyed to the right in Figure 4. At a first work station L2 in Figure 4 (shown also in Figure 6), the container 42 is halted beside a laser 44.The container 42 is then rotated on the suction pad while the laser 44 is focused to cut through the container 42 at a level just below the level of the agar or other nutrient medium 45 in the container 42. After cutting, the upper portion of the container 42 is removed by a blast of compressed air along a nozzle 46. This leaves easy access to the plantlet 43, as shown in Figure 7. Next,at location L3 in Figure 4, the container 42 and plantlet 43 are moved to the right beneath a pair of high speed contra-rotating serrated disc cutters 47, to remove unwanted foliage from the plantlets. The cut foliage is removed by a further blast of compressed air, along a further nozzle (not shown). This leaves the base portions of the plants 43 ready for selection and division, at location L4 in Figure 4, also shown in Figure 8.An exit 53 is provided adjacent location L2 for disposal of upper portions of containers 42 cut by the laser 44. A further exit 54 is provided adjacent locations L3 and L4 for disposal of leaf debris, and spent containers 42 after plants have been removed therefrom as will be described below.

Referring to Figure 4, a robotic end effector 48, positioned at location L5 on an extendible arm 49, may comprise apparatus as shown in Figures la to 3. The next step of the method is effected at location L4, where the container 42 is observed from above by a video camera (not shown) in a vision guidance system, which is linked to the robotic end effector 48, on the arm 49. The end effector 48 is moved to the left, as shown by arrow 50, and is positioned over the container 42. The end effector is then lowered, as has been described, so as to encompass a plantlet to be divided,by the gripping elements 11 shown for example in Figure la. The end effector 48 is then operated through the sequence described previously with reference to Figures la, b, c and Figure 2.The cut plantlet 43 is then lifted by the end effector 48 and moved by the arm 49 to a work station at location L8, where a further container 42 of fresh nutrient medium has been positioned to receive cut plant portions, as has been described with reference to the Figures 2 and 3. The sequence of movement of the fresh container 42 to the location L8 is as follows. A further stacker 51, generally simil-ar to the stacker 40, dispenses containers 42 to iocation!--fl, where the container is placed upon a suction di-cc on-e furthervconveyor (not shown). The fresh container 42 isthen transferred to location L7 where the lid off the container 42 is removed. The container is passed to location L8 where selected cut portions of plant are planted in the nutrient medium. The container 42 is then moved back to location L7, and thence through an exit 52 to a further growing location (not shown).

Claims

1. Apparatus for cutting an object comprising a plurality of elongate gripping elements extending in the same general direction with the distal ends thereof encompassing a region for an object to be cut; control means for controlling movement of the distal ends of the elements towards each other to grip an object to be cut; and cutting means operatively linked to the control means and operable in the said region encompassed by the distal ends of the gripping elements to divide an object gripped by the distal ends of the elements, into divided parts which remain gripped by the gripping elements.

2. Apparatus according to claim 1 in which the control means is moveable longitudinally of the elongate elements and cooperates with the elements to draw the elements together and/or force the elements apart during longitudinal movements of the control member.

3. Apparatus according to claim 1 or 2 in which the cutting means is moveable longitudinally of the elongate elements towards the distal ends thereof to divide an object encompassed by the distal ends of the elements.

4. Apparatus for cutting an object comprising a plurality of elongate gripping elements extending in the same general direction, with the distal ends thereof encompassing-a region for an object to be cut; control means moveable longitudinally of the elongate elements for controlling movement of the distal ends of the elements---towards~-each other to grip an object to be cut; and cuttinQ'-rneans operatively linked to the control means and moveab-le-longitudinally of the elongate elements towards the distal--' ends thereof into the said region encompassed by the distal ends of the gripping elements, so as to divide an object gripped by the distal ends of the elements.

5. Apparatus according to any preceding claim in which the gripping elements are spaced from and arranged regularly around a longitudinal axis of the apparatus, and the control means and cutting means are both arranged to move along the longitudinal axis during operation.

6. Apparatus according to any preceding claim in which the control means is moveable longitudinally of the elongate elements and is cooperatively linked with the elements to force the elements apart during longitudinal movement of the control means away from the distal ends of the elements.

7. Apparatus according to claim 6 in which the distal ends of the gripping elements are spring biased towards each other and the gripping of an object is effected by the spring biassing of the gripping elements.

8. Apparatus according to claim 6 or 7 in which the control means comprises a control member which extends inside the assembly of elongate gripping elements and has bearing surfaces which exert an outward force on the elongate elements during operation of the device.

9. Apparatus according to any of claims 5 to 8 in which the elongate elements include a portion along which the elements diverge from each other and a portion along which the elements are substantially parallel to each other, the arrangement being such that during at least part of the period of operation when the cutting means is cutting the object, the control means is associated with the parallel portions of the elements and no movement inwardly of the distal ends is brought about.

10. Apparatus according to any of claims 1 to 5 in which the control means is moveable longitudinally of the elongate elements and is cooperatively linked with the elements to draw the elements together during longitudinal movement of the control means towards the distal ends of the elements.

11. Apparatus according to claim 10 in which the distal ends of the gripping elements are spring biassed apart and the gripping of an object is effected by the control means drawing the elements together during longitudinal movement of the control means towards the distal ends of the elements.

12. Apparatus according to claim 10 or 11 in which the control means comprises a control member which extends around the outside of the assembly of elongate gripping elements and has bearing surfaces which exert an inward force on the elongate elements during operation of the device.

13. Apparatus according to any preceding claim in which the control means is arranged to commence the movement of the distal ends of the gripping elements towards each other before the cutting means operates in the said region, and an object to be cut is centred by the elements relative to the cutting means before being cut.

14. Apparatus according to any preceding c,laim- in which the cutting means is coupled to the-control means and is moveable" - - therewith.

15. Apparatus according to any preceding claim in which the cutting means comprises one or more blades extending transversely in the region encompassed by the gripping elements, for dividing an object into two or more parts.

16. Apparatus according to claim 15 in which the blade or blades are arranged to extend transversely beyond the said region encompassed by the gripping elements.

17. Apparatus according to any preceding claim in which the cutting means is arranged to extend longitudinally beyond the distal ends of the gripping elements, when at its most distal position.

18. Apparatus according to any preceding claim including means for dislodging from the gripping elements a selected cut portion of an object held by the elements.

19. Apparatus according to claim 18 in which the dislodging means comprises an elongate pushing member positioned so as to be inclined to the general direction of the gripping elements and directed towards the region encompassed by the distal ends of the elements, the pusher member being moveable longitudinally so as to protrude between gripper elements into the region encompassed by the tips of the elements.

20. Apparatus according to claim 18 or 19 in which the dislodging means comprises an elongate pushing member having two fingers adapted to protrude between gripping elements into the region encompassed by the ends of the elements.

21. Apparatus according to any of claims 18 to 20 in which the assembly of gripper elements is rotatable relative to the dislodging means so as to allow successive dislodging of selected portions of the cut object by successive rotation of the gripping elements and operation of the dislodging means.

22. Apparatus according to any preceding claim including drive means for moving the components through a sequence of movements in which the gripping elements are moved towards a first work station for a plantlet to be cut during micropropagation; the gripping elements move together and the cutting means are operated; and the gripping elements move to a second work station for a container of nutrient medium for cut portions of the plantlet.

23. Apparatus according to claim 22 including means for dislodging from the gripping elements a selected cut portion of an object held by the elements, in which the drive means is arranged to include in the sequence of movements the operation of the dislodging means to dislodge a first cut portion of plantlet onto the nutrient medium; translational movement of the gripping elements to a further location on the nutrient medium; rotational movement of the gripping elements; and further operation of the dislodging means to dislodge a further portion of plantlet onto the nutrient medium.

24. A method of cutting an object comprising the steps of positioning around the object the distal ends of a plurality of elongate gripping elements which extend longitudinally in the same general direction; moving the distal ends of the elements towards each other ta grip an object to be cuts and cutting the object-by cutting means operating in the' said regiorr -encompassed-- by the distal ends of the" gripping elements

25. A method according to claim 24 in which the gripping elements are moved towards each other before the cutting means operates in the said region, whereby an object to be cut is centred by the elements relative to the cutting means before being cut.

26. A method according to claim 24 or 25 including operating the cutting means by moving the cutting means longitudinally of the elements towards the distal ends thereof.

27. A method according to any of claims 24 to 26 including the steps of dislodging successively from the gripping elements selected cut portions of the object held by the elements after cutting.

28. A method of manoeuvring plant material during micropropagation comprising the steps of positioning around the plant material the distal ends of a plurality of elongate gripping elements which extend longitudinally in the same general direction; and effecting movement of the distal ends of the elements towards each other to grip the plant material by moving longitudinally of the elements control means which cooperates with the elements.

29. A method of cutting and transporting plant material during micropropagation comprising the steps of presenting at a work station a container containing plantlets growing in a nutrient medium; gripping a plantlet by robotic gripping means; dividing the plantlet into two or more portions by a blade moved downwardly onto the plantlet; lifting the cut plantlet by the gripping means; moving the cut plantlet to a second work station over a fresh nutrient medium; and dislodging a part of the cut plantlet onto the fresh nutrient medium.

30. A method of cutting and transporting plant material during micropropagation comprising the steps of presenting at a work station a container containing plantlets growing in a nutrient medium; cutting an upper portion of the container free from a lower portion which contains the nutrient medium supporting the plantlets; removing the said upper portion of the container to provide access to the plantlets; dividing a plantlet into two or more portions; and transporting to a fresh nutrient medium the cut portions of the plantlet.

31. Apparatus for cutting an and/or manoeuvring object substantially as hereinbefore described with reference to any one or any combination of the accompanying drawings.

32. A method of cutting and/or manoeuvring an object substantially as hereinbefore described with reference to any one or any combination of the accompanying drawings.