Dynamic gripper system for fruit harvesting

Abstract

An autonomous fruit picking device comprising a dynamic gripper drive system consisting of dynamic grippers 6 that allows for fruit to be picked, inspected for quality and deposited into a container 8

Description

FIELD OF THE INVENTION The present invention relates to improvements to automated fruit harvesting systems. The focus of this invention is particularly on the method of driving a dynamic gripper so that it may cut and / or pluck fruit, before then transporting and releasing the fruit into a container that may be automatically replaced once full. The term ‘fruit’ is used to represent any fruit or vegetable and may refer to an individual or a bunch of fruit or vegetables. BACKGROUND OF THE INVENTION The development of automated fruit picking systems is becoming more common place in recent years due to improvements in AI and a growing need for fruit pickers in some parts of the world. The method of picking fruit that is most commonly being developed is ‘pick and return’, which consist of a robotic arm style positioning device with a fruit gripper fixed to the end of the arm. This system operates by detecting a suitable fruit to be picked, it then moves a robotic arm to a position close to the fruit, before then undertaking some fine movements with the arm and / or gripper to pick the fruit. The whole arm is then moved again to transport the fruit towards a sensor system, where the arm may carry the fruit through a validation sensor to confirm its quality, before finally the arm moves to position the fruit over a collection point, where the fruit is deposited. One of the disadvantages of this system is that it requires a large amount of movement from the robotic arm. Accelerating and decelerating the large mass of a robotic arm multiple times takes a relatively long time and a large amount of energy to collect one fruit. This high time and energy penalty can then make the whole system significantly less profitable to the fruit growers and farmers. Another method of automated fruit picking is ‘cut and collect’. Whereby fruit is cut directly from the plant with the intention of the fruit falling into a container or landing on a ramp / slide that the fruit will then travel down to reach a container. This method is more efficient than the afore mentioned method as the main positioning arm does not need to travel so far as it is able to travel from one fruit directly to the next. However, some of the disadvantages of this system are that fruits can be bruised and damaged if dropped or rolled over large distances, it is also difficult to place a container below fruits grown at ground level and finally this system does not easily allow for quality inspection of fruits once they have been picked. The present invention seeks to address the disadvantages associated with these prior art methods. SUMMARY OF THE INVENTION According to an aspect of the invention presented there is provided a dynamic gripper system for fruit harvesting comprising: A drive system, which is carried by a positioning arm or other positioning device; one or more dynamic grippers or other end effectors that are mounted on the drive system and not on the positioning device, where the afore mentioned drive system is able to cycle the end effectors so that they may approach fruit to then cut and / or pluck the fruit, before then transporting and releasing the fruit to a collection area; where the collection area is in a fixed location relative to the positioning device. This system is advantageous over ‘pick and return’ style developments due to an increased speed and efficiency, as the main positioning device will only need to move a small distance from one fruit, directly to the next. This is achieved by having a smaller drive system, to which the dynamic grippers are mounted, where only the small mass of the drive system and dynamic grippers will need to be accelerated and decelerated whilst picking fruit, transporting the fruit through quality inspection sensing, and then releasing the fruit into a collection area. The advantages over the ‘cut and collect’ style developments include the present invention being able to pick and gather fruits from both high and ground level plants in order to then transport the picked fruit back to a collection point. The present invention is also able to verify the quality of the picked fruit and then determine whether to deposit the fruit (if acceptable) or to release (if unacceptable). Another advantage is that the fruit is released into a collection area, which will always be at a consistent height relative to the dynamic grippers, reducing the chances of a fruit being bruised or damaged as they are released into the collection area. An additional benefit of the present system is that the collected fruit is weighed to ensure that the correct amount of fruit is deposited. Once a container is considered full, it is automatically replaced by another empty container that is held by this device. Once all held containers are considered full, this device is able to deposit all full containers at a replenishment station, before restocking on empty containers allowing it to continue picking fruit with minimal human intervention required. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of this invention will now be described, by way of example only, with reference to the following drawings, in which: Figure 1 shows a perspective view of an automated fruit harvesting system including a dynamic gripper system according to the present invention; Figure 2 shows a perspective view from a different angle of the automated fruit harvesting system; Figure 3 shows a bottom view of the dynamic gripper drive system for fruit harvesting according to the present invention, wherein a dynamic gripper is in the process of gripping a fruit; Figure 4 shows a bottom view of the dynamic gripper drive system for fruit harvesting according to the present invention, wherein a gripped fruit is being transported by a dynamic gripper via a quality verification sensor; Figure 5 shows a bottom view of the dynamic gripper drive system for fruit harvesting according to the present invention, wherein a dynamic gripper is releasing a fruit into the collection area; Figure 6 shows a cut away elevation view of an automated fruit harvesting system including an onboard container replacement system. Figure 7 shows a plan view of an automated fruit harvesting system including a container conveyor and diverter system. DETAILED DESCRIPTION The fruit harvesting device can be seen in Figure 1 and Figure 2, these show a positioning device, in this case a positioning arm that is made up of an end positioning arm (1), which is pivotally mounted onto a positioning arm link (2), which in turn is pivotally mounted to the positioning arm base (3). The positioning arm base (3) is rotationally mounted to the transport carriage (4) in such a way that the positioning arm base may rotate 360° around the vertical axis, this is driven by a motor drive system that is located in the transport carriage. The positioning arm link (2) may rotate at approximately 180° around an axis perpendicular to the rotational axis of the positioning arm base. This is driven by a motor drive system located in the positioning arm base. The end positioning arm (1) may rotate approximately 270° around a parallel axis to that of the positioning arm link. This is driven by an additional motor system located in the positioning arm base, which then carries this drive through a belt that runs along the inside of the positioning arm link to connect with the end positioning arm. An end sensor (5) is mounted to the end positioning arm (1). This end sensor will be an optical sensor used to image fruit to ensure that the fruit is ripe and ready to be picked and it will also be used to determine the locations of these fruit and to aid the positioning device to reach a suitable position for picking the selected fruit. The dynamic grippers (6) are used for picking and transporting the fruit, these are not mounted to the end positioning arm and are instead mounted to a separate internal drive system, which is not shown in these figures. These will both be described in more detail later. The conveyor (7) is mounted to the transport carriage (4) in such a way that it may carry a plurality of containers (8) around the positioning arm, where a portion of the conveyor rotates concentrically to the rotation of the positioning arm base (3). A motor drive system for the conveyor is located within the transport carriage. A container carrier (9) is mounted to the end positioning arm (1). A held container (10) is carried by the container carrier so that it is below the collection area. A diverter (11) is rotationally mounted to the transport carriage (4) in such a way that it may be opened to block a portion of the conveyor path to divert containers (8) from the conveyor (7). This diverter is passively opened and across the path and will naturally spring back to the position shown in these figures. Conveyor wheels (12) are rotationally mounted to the transport carriage and are located in the area that containers are diverted to from the conveyor, these conveyor wheels are used to continue transporting containers once they leave the conveyor. The container wheels are driven by the same shared motor drive as the conveyor and are geared in such a way that they will match transportation speed with the conveyor. An external drive (13) also shares this drive, this is rotationally mounted to the front face of the transport carriage and is used to drive external drive systems that are not on the autonomous fruit harvester. Object sensors (14) are mounted to the front and rear of the transport carriage (4), these are used to detect objects and to allow the transport carriage to travel autonomously whilst avoiding potential obstacles. In addition to the object sensors, the transport carriage will use GPS positioning to aid navigation. The transport carriage is shown with transport carriage wheels (15), however these are shown as an example only and any means of propulsion and steering could be used, such as, but not limited to wheels, tracks or rails. These propulsion and steering components will require their own motor drive systems, which will be mounted to the transport carriage. Figure 3, Figure 4 and Figure 5 show a bottom view of the dynamic gripper drive system. These figures depict the dynamic grippers through different stages of a fruit (16) being picked, inspected for quality and deposited. The dynamic gripper drive system is mounted to the end positioning arm (1). The end positioning arm is driven by a belt drive (17), which is located within a positioning arm link (2). The end sensor (5) is used to locate and image fruit (16) to be harvested. The ripeness of the imaged fruit is determined by a neural network, which is trained with data representing fruit at three categorised stages un-ripe, ripe and over-ripe. Once a ripe fruit has been located the positioning arm will move to a position that will allow the dynamic gripper drive system to pick and process the fruit. The purpose of the dynamic gripper drive system is to be able to pluck, transport, verify the quality and to deposit the fruit (16) in a time and energy efficient manner. This system comprises a drive system made up of a driven sprocket (18) that is rotationally mounted to the end positioning arm and is driven by a motor drive that is mounted to the end positioning arm. A drive chain (19) is located on the driven sprocket and is driven in a rotational manner by the driven sprocket. An arrow in Figure 3 demonstrates the forward direction that the chain is driven whilst collecting fruit. An idle sprocket (20) is also used to guide the drive chain. A number of dynamic grippers (6) are mounted to the drive chain, whereby they are driven to a point from which they protrude from the end positioning arm into an area that the desired fruit is located. The dynamic grippers are interchangeable as multiple types are needed to work with specific types of fruit. The dynamic grippers can actuate at certain points along their path, this actuation is driven by a cam profile (not shown). As a dynamic gripper protrudes from the end positioning arm towards a fruit, the dynamic gripper is actuated by the cam profile to close around the fruit or the stem, thereby severing the fruit from the plant, whilst simultaneously gripping the fruit. This operation stage is shown in Figure 3. The dynamic gripper (6) will remain closed as the fruit (16) is transported along the path of the drive chain (19), whereby the fruit will pass a quality verification sensor (21). This operation stage is shown in Figure 4. Similarly to the end sensor (5), the quality verification sensor will image the fruit to confirm its ripeness. This sensor will also verify that what has been picked is what was intended, for example to ensure that no unwanted leaves were picked. If the quality of the fruit picked is not successfully verified by the quality verification sensor, then the drive chain is ran in reverse until the dynamic gripper protrudes back from the end positioning arm and the dynamic gripper is re-opened due to the cam profile to release the gripped contents. If the quality of the picked fruit is successfully verified the drive chain continues forward, the cam profile is such that the dynamic gripper opens as it passes above the collection area (22). As the dynamic gripper opens the fruit is released into the collection area. This operation stage is shown in Figure 5. The dynamic gripper drive system can continue to be driven to then continue plucking, transporting, verifying and depositing fruits. Each time a fruit is picked the positioning arm can move directly to the next fruit in preparation for the dynamic grippers to protrude and pick the fruit. As most fruits generally grow in close proximity to each other, the large mass of the positioning arm only has to be accelerated and decelerated over a short distance. This allows for a large amount of fruits to be collected in a relatively short amount of time whilst also using a relatively low amount of energy. Figure 6 and Figure 1 show the automated fruit harvester in a way that will aid description of the onboard container replacement system. As the containers (8) are travelling along the concentric portion of the conveyor (7), they may be collected and held, one at a time, by the container carrier (9). The container carrier is mounted to the end positioning arm (1). This may prepare to collect one of the containers by lowering the container carrier down towards the conveyor at a point that there are no containers (23). The container carrier has two lifting ridges, which it uses to pick up containers. The conveyor will then rotate, carrying one of the containers to a stopping point where the container is able to slot in between the two lifting ridges of the container carrier, which is parked with these lifting ridges slightly lower than the outer rim of the container. As the positioning arm is raised the container carrier is lifted so that the lifting ridges make contact with the outer rim of the container, which then lifts the container. This container is now considered a held container (10) and is located below the collection area (21) at a fixed-distance relative to the end positioning arm. Any fruit that are released into the collection area will then land in the held container. As the held container (10) is filled with fruit, both the held container and the fruit are weighed by a weight transducer. Once the correct weight of fruit has been deposited into the held container it is considered full. The end positioning arm (1) is then lowered towards the conveyor (7) so that this full container may be lowered onto the conveyor. As the full container is lowered onto the conveyor, the end positioning arm and the container carrier (9) are lowered slightly further, so that the conveyor can be rotated to carry the full container away from the container carrier. As this is done one of the empty containers (8) are carried to a point that they are in line with the container carrier, ready to be picked up and fdled in the same manner as the previous container. This can be repeated until all containers are full of fruit. Figure 7 and Figure 1 show the automated fruit harvester in a way that will aid description of the means that this device will drop off full containers at a fixed replenishment station to then be able to resupply with empty containers automatically, in order to continue harvesting fruit without requiring human intervention. Once all containers (8) have been filled with fruit they can be deposited at a fixed container replenishment station. The transport carriage (4) autonomously travels to the nearest empty replenishment station. It is able to do this by using a combination of built in GPS and object detection from the object sensors (14). The location of the replenishment stations are inputted into the transport carriage as GPS co-ordinates. The station comprises a table or other fixed structure that has an undriven conveyor system that is the same height as the onboard conveyor (7). The transport carriage is then able to dock with this station in such a way that the conveyor wheels (12) align with the conveyor system of the replenishment station. The docking process is guided by the object sensors. On docking, the external drive (13) will also align with an idle drive train for this station’s conveyor, allowing this conveyor to be driven by the automated fruit harvester. As the transport carriage docks, the diverter (11) is passively opened by a protrusion from the replenishment station. This creates a clear path for the full containers to be transferred from the onboard conveyor, across the conveyor wheels and onto the replenishment station’s conveyor that will continue to carry the initial containers away as the remaining containers are passed from the automated fruit harvester onto the replenishment station. With all the full containers (8) now transferred from the fruit harvester, the transport carriage (4) travels to the nearest replenishment station that is loaded with empty containers. It may then dock in the same manner as previously described, however this time the external drive (13) is ran in reverse, which will drive the empty containers from this replenishment station over the conveyor wheels (12) and onto the conveyor (7) of the fruit harvester. Thus, replenishing the fruit harvester with empty containers, ready to be filled with more fruit. The fruit harvester is powered by one or more on-board batteries. Once the energy in these batteries drops below a certain point, the fruit harvester will locate the nearest available charging station. These charging stations can also be located based on their GPS locations. To dock with a charging station, the fruit harvester will again use the object sensors (14) to determine correct alignment. During docking an electrical connection is made between the fruit harvester and the docking station, which is connected to mains electricity. The fruit harvester will remain docked until the battery is considered sufficiently re-energised. At which point the fruit harvester can continue with its objective of collecting fruit. This allows the fruit harvester to continuously operate until all replenishment stations are loaded with containers full of fruit.

Claims

22 08 251. A dynamic gripper system for fruit harvesting comprising:A drive system, which is carried by a positioning device;end effectors are mounted on the drive system and not on the positioning device, where the afore mentioned drive system is configured to cycle the end effectors along a set path, at one point along the set path is a mechanical actuator configured to engage the end effectors to cause the plucking of fruit, at a separate point of the set path is another mechanical actuator configured to engage the end effector to cause the release of the fruit into a collection area;where the collection area is in a fixed location relative to the positioning device.

2. A dynamic gripper system for fruit harvesting as in claim 1, wherein the system comprises an actuator arrangement for actuating the end effectors at desired points along the drive system.

3. A dynamic gripper system for fruit harvesting as in claim 2, wherein the actuator arrangement comprises a cam profile configured to engage the end effectors.

4. A dynamic gripper system for fruit harvesting as in claim 1, wherein the end effectors are configured to hold the fruit by the stem or stalk.

5. A dynamic gripper system for fruit harvesting as in claim 1, comprising a sensing system, which is positioned to validate that the picked fruit is satisfactory as it is transported by the end effectors.

6. A dynamic gripper system for fruit harvesting as in claim 5, wherein upon a determination that a picked fruit is unsatisfactory, the drive system is configured to operate in a reverse direction to release the unsatisfactory fruit outside of the collection area.

7. A dynamic gripper system for fruit harvesting as in claim 1, wherein the drive system is made up of a rotary drive mechanism.

8. A dynamic gripper system for fruit harvesting as in claim 7, wherein the drive system is driven by a sprocket, which rotates around a central pivot point, which is fixed to the positioning device.

9. A dynamic gripper system for fruit harvesting as in claim 1, where the positioning device is made up of a plurality of positioning arm links.

10. A dynamic gripper system for fruit harvesting as in claim 1, wherein the end effectors are configured to release the fruit into a collection area.

11. A dynamic gripper system for fruit harvesting as in claim 1, wherein a container is held at the collection area, where released fruit are deposited in the aforementioned container.

12. A dynamic gripper system for fruit harvesting as in claim 11, wherein a weight sensor is arranged to measure fruit in the container to determine when the container is full.

13. A dynamic gripper system for fruit harvesting as in claim 11-12, wherein a full container that is held in the collection area is automatically replaced with another container by the system.

14. A dynamic gripper system for fruit harvesting as in claim 11-13, wherein a conveyor carries a plurality of containers within reaching proximity of the container carrier, which is mounted to the positioning device.

15. A dynamic gripper system for fruit harvesting as in claim 11-14, wherein the positioning device is configured to lower and release a full container on the conveyor.22 08 2516. A dynamic gripper system for fruit harvesting as in claim 11-15, wherein a full container that has been released on the conveyor is replaced with an empty container by the system, and wherein the positioning device is then configured to lift the empty container into the container carrier.

17. A dynamic gripper system for fruit harvesting as in claim 1, wherein the positioning device is mounted onto a transport carriage.

18. A dynamic gripper system for fruit harvesting as in claim 1-17, wherein the conveyor system is mounted onto the transport carriage.

19. A dynamic gripper system for fruit harvesting as in claim 1-18, wherein the transport carriage is configured for autonomously transporting the positioning arm to close proximity of a plurality of fruit plants.

20. A dynamic gripper system for fruit harvesting as in claim 1-19, wherein the transport carriage is configured to dock with a container replenishment station, wherein full containers are deposited, and empty containers collected onto the transport carriage mounted conveyor.

21. A dynamic gripper system for fruit harvesting as in claim 20, wherein the container replenishment station consists of a plurality of conveyors that are mounted at a height similar to the transport carriage mounted conveyor.

22. A dynamic gripper system for fruit harvesting as in claim 20-21, wherein the conveyors of the container replenishment station are driven by an external drive of the transport carriage.

23. A dynamic gripper system for fruit harvesting as in claim 1-19, wherein the transport carriage is configured to dock with a recharging station for energy replenishment.

24. A dynamic gripper system for fruit harvesting as in claim 1-19, comprising sensors configured to image fruits, and a processor comprising a neural network configured to determine the ripeness and location of the fruit from the images.

25. A dynamic gripper system for fruit harvesting as in claim 1-19, wherein sensors are mounted on the transport carriage for object avoidance whilst the autonomous transport carriage is in motion.

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