Device, system and method

Abstract

A device 1 for passively cutting an elongate part or stem S of a plant, e.g., asparagus, where the device comprises a cutter or blade 2 to cut the stem, an enclosure 3 to partially surround the stem w

Description

TECHNICAL FIELD The present disclosure relates to a device for cutting an elongate part of a plant, such as a stem, a robotic system comprising the device and a method of cutting a stem of a plant using the device. BACKGROUND ART Harvesting delicate produce, such as asparagus, that grows from below the ground (e.g. from seed, bulb or tuber) is typically very labour intensive, with most produce still picked by hand. This typically involves a worker carefully grasping and cutting the stem of the plant. Most mechanical harvesting methods are not suitable for delicate produce, such as asparagus, because the produce is easily damaged. Various robotic systems have been devised to replace a human worker. Typically, these comprise a contact-grasping mechanism to grasp the stem of the produce prior to cutting, and a solenoid or pneumatically actuated blade to cut the stem. However, both the contactgrasping mechanism and actuated blade can bruise or otherwise damage the produce. This can lead to water and nutrient loss, diminished flavour, and an increased risk of decay and spoilage. Furthermore, complex contact-grasping mechanisms and actuated blades increases the likelihood of device failure, thus reducing reliability. It is an aim of the present disclosure to at least partially address one or more of the above problems. SUMMARY OF THE INVENTION According to an aspect of the disclosure, there is provided a device for cutting an elongate part of a plant, the device comprising: a cutter configured to cut the elongate part, an enclosure extending substantially in a first direction and configured to at least partially surround an axis extending in the first direction, wherein the enclosure is configured to receive at least a portion of the elongate part to be cut by the cutter, such that the received 1 portion of the elongate part extends substantially in a direction parallel to the first direction, and the enclosure is configured to retain the elongate part after the elongate part is cut by the cutter. Optionally, the enclosure is configured so as not to contact the elongate part before the cutter cuts the elongate part. Optionally, the enclosure is configured to catch the elongate part after it is cut. Optionally, the enclosure comprises an opening configured to permit the elongate part to enter the enclosure. Optionally, the opening is arranged adjacent the axis in a direction perpendicular to the axis. Optionally, the opening extends substantially in a first direction. Optionally, the enclosure comprises a closure mechanism configured to at least partially close the opening after the elongate part is cut. Optionally, the closure mechanism is configured to close as a cutting action is performed to cut the elongate part. Optionally, the closure mechanism comprises a hinged portion of the enclosure. Alternatively the closure mechanism comprises a sliding portion of the enclosure. Optionally, the cutter is arranged at a base portion of the enclosure. Optionally, the cutter is fixed with respect to the enclosure. Optionally, the cutter is configured to passively cut the elongate part, the movement of the cutter relative to the elongate part being provided by movement of the enclosure. Optionally, the cutter comprises a blade. Optionally, the device is configured to be attached to a robotic arm configured to move the device. According to a second aspect of the disclosure, there is provided a robotic system comprising a robotic arm to which the device of any preceding claim is mounted, the robotic arm being configured to move the device to cut the elongate part. Optionally, the robotic system further comprises a moveable platform to which robotic arm is mounted, wherein the moveable platform comprises transportation means. Optionally, the robotic system further comprises a sensor configured to sense the position of an elongate part of a plant to be cut, and a controller configured to control the robotic system to cut the elongate part. According to a third aspect of the disclosure, there is provided a method of cutting an elongate part of a plant, the method comprising: using the device or robotic system according to any preceding claims to cut the elongate part. Optionally, the method comprises performing a cutting action, the cutting action comprising moving the device, in a cutting direction, from a position in which the elongate part is outside the enclosure, towards the elongate part, such that the elongate part moves into the enclosure and is then cut by the cutter. Optionally, the method further comprises performing a positioning action before performing the cutting action, the position action comprising moving the device relative to the elongate part to be cut, to a position at which the elongate part is outside the enclosure and from which the cutting action can be initiated. Optionally, the method comprises performing a release action to release the cut elongate part from the enclosure. Optionally, the method further comprises performing the cutting action in respect of a subsequent elongate part, after performing the release action for a previous elongate part, and optionally performing the positioning action between the release action and the cutting action in respect of a subsequent elongate part. Optionally, the method is performed by the robotic system of the second aspect. 3 A computer programme product which, when executed by computer, is configured to cause the robotic system of the second aspect to execute the method of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS Further features of the disclosure will be described below, by way of non-limiting examples and with reference to the accompanying drawings, in which: Fig. 1 shows a first configuration of a device according to the disclosure; Fig. 2 shows a second configuration of a device according to the disclosure; Fig. 3 shows a third configuration of a device according to the disclosure; Fig. 4 shows a robotic system according to the disclosure; Fig. 5 shows a modified device according to the disclosure. DETAILED DESCRIPTION Fig. 1 shows an example device 1 for cutting an elongate part of a plant, such as a stem S, according to the disclosure. For simplicity, the elongate part of a plant is referred to below as a stem S. However, it should be understood that the elongate part need not be a stem. For example, the elongate part could be another part of the plant, such as a branch, leaf or leaves, fruit, or other part. The elongate part may be a part of the plant that extends from the ground, e.g. is located close to the ground. In a specific example, the elongate part may be an asparagus stem. As shown, the device 1 comprises a cutter 2 configured to the cut the stem S of the plant. As shown the cutter 2 may comprise a blade. The blade may be a utility blade, for example. As shown in Fig. 1, the device 1 further comprises an enclosure 3. As shown, the enclosure 3 extends substantially in a first direction and is configured to at least partially surround an axis (shown by the dashed arrow in Fig. 1) extending in the first direction. The enclosure 3 is configured to receive at least a portion of the stem to be cut by the cutter 2 such that the received portion of the stem extends substantially in a direction parallel to the first direction and configured to retain the stem after the stem is cut by the cutter 2. 4 The enclosure 3 may be configured so as not to contact the stem S before, and / or during, cutting of the stem S by the cutter 2. For example, the stem S may not be supported by the enclosure before cutting and while the stem S is within the enclosure. For example, a gap may be maintained between the enclosure and the stem S before and / or during cutting. The enclosure 3 may be configured to catch the stem S after it is cut. For example, before cutting, the stem S may be self-supported and after cutting, a cut portion of the stem S may become unsupported by the rest of the stem S and fall under gravity to contact and be supported by the enclosure 3. Accordingly, the stem S is not gripped by the device 1 before or during cutting. As shown in Fig. 1, the enclosure may comprise a plurality of adjacent side wall portions 31 to 34 extending substantially in the first direction. As shown, the enclosure may comprise four side wall portions. Side wall portions may be substantially flat and / or curved, for example. In other examples, other numbers and configurations of wall portions may be used. Side wall portions of the enclosure may define a space enclosed by the enclosure into which the stem S is configured to be received during and / or after cutting. As shown in Fig. 1, the enclosure 3 may comprise an opening 4 configured to permit the stem S to enter the space within the enclosure 3. As shown, the opening 4 may be arranged to be adjacent the axis in a direction perpendicular to the axis. As shown, the opening 4 may extend substantially parallel to the axis. The opening 4 may be provided at least at a portion of the enclosure 3 adjacent to the cutter 2, e.g. at the base of the enclosure 3. As shown, the opening 4 may span the entire length of the enclosure 3 in the extension direction of the enclosure 3. As shown in Fig. 1, the opening 4 may extend in a width direction perpendicular to the axis. The opening 4 may be longer than it is wide, to correspond with the elongate shape of the stem S to be cut. The width of the opening 4 may be at least as wide as the width of a stem S to be cut. As shown in Fig. 1, the enclosure 3 may comprise a closure mechanism configured to at least partially close the opening 4 after the stem S is cut. This may reduce the likelihood of the cut stem S leaving the enclosure 3 via the opening 4. The closure mechanism may 5 comprise a moving side wall portion of the enclosure 3, for example. The moving side wall portion may be configuring to move relative to a fixed portion the device 1. As shown, the opening 4 may be provided in the fixed portion of the enclosure 3. The fixed portion the device 1 may comprise further wall portions of the enclosure. As shown in Fig. 1, wall portion 34 may be a moving wall portion and wall portions 31 to 33 may be fixed wall portions. As shown in Fig, 1, the closure mechanism may be a hinged closure mechanism. The moving side wall portion may comprise a hinged portion 34 of the enclosure 3. Hinged movement may be provided between the hinged portion 34 and the fixed portion of the enclosure 3. A hinge 36 may be connected between the hinged portion 34 and another portion of the enclosure to allow the hinged portion to close. As shown, the hinged portion may be a side wall portion 34 forming the enclosure 3 and the other portion of the enclosure may be an adjacent wall portion 33 forming the enclosure 3. Fig. 5 shows a modified example device 1, according to the disclosure. The example device shown in Fig. 5 is substantially the same as the example device described above. Accordingly, most of the features and functions described above also apply to the modified device of Fig. 5. As shown in Fig. 5, the device 1 may comprise a sliding closure mechanism. Accordingly, the moving side wall portion may comprise a sliding portion 34 of the enclosure 3. Sliding movement may be provided between the sliding portion 34 and the fixed portion of the enclosure 3. As shown, the sliding portion may be a wall portion 34 forming the enclosure 3. The sliding may be driven by a motor 37. The sliding portion 34 may slide in a rotational motion, as shown between the left and right parts of Fig. 5. As shown, the axis of rotation may be a substantially central axis through the enclosure. As shown, the enclosure and / or the sliding portion may be shaped to form a portion of a cylindrical surface. As shown, the opening may 4 be provided in the fixed portion 31 to 33 of the enclosure 3 and a further opening may be provided in the sliding portion 34. In the open configuration, the respective openings may be aligned and in the closed configuration the respective opening mas be misaligned. Other types of closure mechanism may be used alternatively. Some closure mechanisms may comprise two or more moving portions. The closure mechanism may be electrically actuated, for example, e.g. by one or more solenoids. Other means of actuation may be used alternatively, e.g. pneumatic actuation. The closure mechanism may be configured to close (e.g. actuate from an open configuration to a closed configuration) after the stem S has entered the space defined by the enclosure 3. The closure mechanism may be configured to close (e.g. actuate from an open configuration to a closed configuration) before the stem S is completely cut by the cutter 2. The closure mechanism need not be completely closed before the stem S is completely cut. For example, the closure mechanism may be completely closed shortly after the stem S is completely cut, but within a period of time that renders the likelihood of the stem S leaving the enclosure 3 through the opening sufficiently small. As shown in Fig, 1, the enclosure 3 may further comprise a base. As shown, the cutter 2 may be provided at the base of the enclosure 3. For example, as shown, the cutter 2 may be integrated into a base wall portion 35 of the enclosure 3. As shown, the cutter 2, e.g. a blade thereof, may be arranged to face the opening 4. As shown, the cutter 2 may be arranged substantially parallel to the base portion, e.g. in plane substantially perpendicular to the axis. As shown in Fig. 1, the cutter may be provided in a fixed portion of the device 1. The fixed portion of the device may be moved relative to the stem S such that the stem S contacts the cutter 2. Accordingly, as the stem S moves into the enclosure 3 through the opening 4, the stem S approaches, contacts and is then cut by the cutter. The momentum of the device 1 may provide the force required for the cutter to cut the stem S. In this example, the cutter 2 is a passive cutter and is not itself actuated relative to a fixed portion of the device 1. The device 1 may be configured to move in a cutting direction, indicated by the solid arrow in Fig. 1, to cut the stem S. As shown, the cutting direction may be substantially perpendicular to the axis and in the direction of the opening with respect to the axis. As shown the cutter 2, e.g. a blade, may be provided at an angle with respect to the cutting direction. As shown in Fig. 4, the device 1 may be mounted to a robotic system 100 configured to move the device 1 relative to the stem S to perform cutting. As shown, the robotic system 100 may comprise a robotic arm 101. The device 1 may be mounted to the robotic arm 101, e.g. by a connector 102. Accordingly, the device 1 can be regarded as an end effector for a robotic arm. As shown in Fig. 4, the robotic system 100 may further comprise a platform 103 to which the robotic arm 101 is mounted. As shown, the robotic system 100 may further comprise transportation means for transporting the robotic system 100. As shown, the transportation means may comprise wheels 104. Alternative transportation means may be used instead, such as tracks instead of wheels. The transportation means may be provided to the platform 103, as shown. The robotic system 100 may be configured to perform a cutting action. The cutting action may comprise movement of the device 1, in the cutting direction, from a position in which the stem S is outside the enclosure 3, towards the stem, such that the stem S moves into the enclosure 3 through the opening 4 and is then cut by the cutter 2. Preferably, this cutting action is performed as a continuous movement. The cutting action may be performed by movement of the robotic arm 101, e.g. only movement of the robotic arm 101 when the robotic system 101 is otherwise stationary relative to the stem S. Prior to performing the cutting action, the robotic system 100 may be configured to perform a positioning action. The positioning action may comprise moving the device 1 relative to the stem S to be cut, to a position at which the stem S is outside the enclosure 3 and from which the cutting action can be initiated. This position may be a predefined distance from the stem S, for example. The positioning action may comprise orienting the device 1 to have an orientation relative to the stem S from which the cutting action can be initiated. This orientation may be such that the opening 4 faces the stem S and the stem S is positioned in the cutting direction, for example. The positioning action may be performed by movement of the robotic arm 101 and / or movement of the robotic system 100 as a whole, e.g. by the transportation means. For example, the robotic system 100 may be moved to a position at which the stem S is within range of the device 1 mounted to the robotic arm 101, said range being a range in which 8 the cutting action can be performed to cut the stem S. The robotic arm 101 may be moved to position the device 1 as described above. Movement of the robotic arm 101 may be performed before during or after movement of the robotic system 100, but preferably after movement of the robotic system 100. A part of the positioning action that is performed by the robotic arm 101 may be performed continuously with the cutting action, for example. Alternatively, the robotic arm 101 may pause (e.g. come to a stop) between the positioning action and the cutting action. The robotic system 100 may be controlled by a controller, e.g. comprising one or more CPUs. The controller may be configured to control the movement of the robotic system 100, including movement of the robotic arm 101. The controller may further be configured to control the closure mechanism. The controller may be configured to control the movement of the robotic system 100, including movement of the robotic arm 101, based on position data relating to the position of a stem S to be cut relative to the robotic system 100. The position data may be determined by one more sensors 105 of the robotic system 100. As shown in Fig. 4, the sensors 105 may comprise a visible light imaging sensor, for example (e.g. an RGB camera). As show, the sensors 105 may additionally comprise a range finding sensor configured to determine a distance to an object. Alternative types of sensors may be used to determine the position of a stem S alternatively or additionally, such as infrared sensors, millimetre wave sensors, microwave sensors, and Lidar. Raw sensor data may be processed by the controller to determine the position of a stem S to be cut. The sensor data may be processed to determine which object (or objects) is a stem S, as well as the position of an identified stem S. The closure mechanism may be configured to close during the cutting action. This may allow the closure mechanism to be closed after the stem S has entered the space defined by the enclosure 3, but before or shortly after the stem S is completely cut by the cutter 2. For example, the closure mechanism may be configured to initiate closing at a predefined time or position of the device 1 during the cutting action. The timing or position will in part depend on the speed at which the closure mechanism can close relative to the speed at which cutting is performed. The closure of the closure mechanism may be controlled by the controller. Figs 1 to 3 show a sequence forming part of a cutting action of the example device shown. Fig. 1 shows the device 1 immediately before initiation of the cutting action. Fig. 2 shows the device 1 immediately before the cutter 2 contacts the stem S, near the middle of the cutting action. Fig. 3 shows the device 1 as the cut is completed, towards the end of the cutting action. As can be seen from this sequence, the closure mechanism is completely open as the cutting action commences, and closes during the cutting action, to be completely closed (though not shown) shortly after the stem S is completely cut. After the cutting action is completed, the stem S is retained within the enclosure 3. For example, the stem S may be supported by the side walls and / or the the base of the enclosure 3. A release action may then be performed to release the cut stem S from the enclosure 3. The release action may comprise opening the closure mechanism, so that the cut stem S can leave the enclosure 3. The release action may further comprise orienting the device 1 such that the cut stem S can fall from the enclosure 3 under gravity. For example, this may comprise orienting the device 1 so that the opening 4 faces substantially downwards in the direction of the gravitational force. The release action may further comprise moving the device 1 to a predefined release position, before the cut stem S is released, for example to be positioned over a predefined collection area and / or container. The collection area and / or container may form part of the robotic system 100 itself. That the release action may be performed only by the robotic arm 101. The robotic system 100 may be configured to automatically cut a plurality of stems S in succession, by cyclically performing the positioning action, cutting action and release action as described above (e.g. under control of the controller). The robotic system 100 may be configured to automatically move from one stem S to the next without human user intervention. It should be understood that the above described examples are for illustrative purposes only and the invention may otherwise be implemented without departing from the spirit or scope of the invention as defined by the appended claims.

Claims

1. A device for cutting an elongate part of a plant, the device comprising:a cutter configured to cut the elongate part,an enclosure extending substantially in a first direction and configured to at least partially surround an axis extending in the first direction,wherein the enclosure is configured to receive at least a portion of the elongate part to be cut by the cutter, such that the received portion of the elongate part extends substantially in a direction parallel to the first direction, and the enclosure is configured to retain the elongate part after the elongate part is cut by the cutter.

2. The device of claim 1, wherein the enclosure is configured so as not to contact the elongate part before the cutter cuts the elongate part.

3. The device of any preceding claim, wherein the enclosure is configured to catch the elongate part after it is cut.

4. The device of any preceding claim, wherein the enclosure comprises an opening configured to permit the elongate part to enter the enclosure.

5. The device of claim 4, wherein the opening is arranged adjacent the axis in a direction perpendicular to the axis.

6. The device of claim 4 or 5, wherein the opening extends substantially in a first direction.

7. The device of any one or claims 4 to 6, wherein the enclosure comprises a closure mechanism configured to at least partially close the opening after the elongate part is cut.

8. The device of claim 7, wherein the closure mechanism is configured to close as a cutting action is performed to cut the elongate part.

9. The device of claim 7 or 8, wherein the closure mechanism comprises a hinged portion of the enclosure.

10. The device of claim 7 or 8, wherein the closure mechanism comprises a sliding portion of the enclosure.

11. The device of any preceding claim, wherein the cutter is arranged at a base portion of the enclosure.

12. The device of any preceding claim, wherein the cutter is fixed with respect to the enclosure.

13. The device of any preceding claim, wherein the cutter is configured to passively cut the elongate part, the movement of the cutter relative to the elongate part being provided by movement of the enclosure.

14. The device of any preceding claim, wherein in the cutter comprises a blade.

15. The device of any preceding claim, wherein the device is configured to be attachedto a robotic arm configured to move the device.

16. A robotic system comprising a robotic arm to which the device of any preceding claim is mounted, the robotic arm being configured to move the device to cut the elongate part.

17. The robotic system of claim 15, further comprising a moveable platform to which robotic arm is mounted, wherein the moveable platform comprises transportation means.

18. The robotic system further of any one of claims 15 to 17 comprising a sensor configured to sense the position of an elongate part of a plant to be cut, and a controller configured to control the robotic system to cut the elongate part.

19. A method of cutting an elongate part of a plant, the method comprising: using the device or robotic system according to any preceding claims to cut the elongate part.

20. The method of claim 19, wherein the method comprises performing a cutting action, the cutting action comprising moving the device, in a cutting direction, from aposition in which the elongate part is outside the enclosure, towards the elongate part, such that the elongate part moves into the enclosure and is then cut by the cutter.

21. The method of claim 20, wherein the method further comprises performing a positioning action before performing the cutting action, the position action comprising moving the device relative to the elongate part to be cut, to a position at which the elongate part is outside the enclosure and from which the cutting action can be initiated.

22. The method of any one of claims 19 to 21, the method comprising performing a release action to release the cut elongate part from the enclosure.

23. The method of claim 22, comprising performing the cutting action of claim 20 in respect of a subsequent elongate part, after performing the release action for a previous elongate part, and optionally performing the positioning action between the release action and the cutting action in respect of a subsequent elongate part.

24. The method of any one of claims 19 to 23, wherein the method is performed by the robotic system of any one of claims 16 to 18.

25. A computer programme product which, when executed on by computer, is configured to cause the robotic system of any one of claims 16 to 18 to execute the method of any one of claims 19 to 23.

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