The present invention relates to robot end effectors for fish injection and associated methods.

Background Art

Fish vaccination by injection is used to keep fish healthy and disease-free. Automation of fish vaccination using robotics reduces cost and increases throughput. However, vaccination requires careful handling of live fish, which is difficult to do with a robot. The fish are anesthetized to aid safe handling, but rough handling still should be reduced to a minimum to ensure the health and welfare of the fish.

In robotics, an end effector is the device at the end of a robotic arm, designed to interact with the environment. An end effector is also known as an End of Arm Tool (EOAT).

For live fish handling, the end effector must grasp the fish. However, all types of conventional prehensile (grasping) end effectors can harm the fish. For example, robotic prehension using impactive grippers such as jaws or claws, which physically grasp by direct impact upon the fish, can damage the body of the fish. Other forms of robotic prehension are unsuitable for live fish handling. These include using ingressive grippers (pins, needles or hackles which physically penetrate the surface of the fish) or contigutive grippers requiring direct contact for adhesion to take place (such as glue, surface tension or freezing).

An astrictive gripper that applies attractive forces to the fish body surface by suction is relatively gentle, but still has problems.

N020170365A discloses a method for automated vaccination of fish, which involves anesthetized fish. It discloses a system for automated vaccinating and sorting live fish, which comprises a retaining device preferably using suction to retain the fish for the vaccination device. A problem with such an approach is a likelihood of injury to fish by use of suction to retain the fish while being injected and moved. A large amount of suction force is needed to secure the fish by acting against the forces related to movement and injection that are also applied to the fish. The suction cups apply large forces to a relatively small area of the fish, which can damage the body of the fish.

A problem with intra-peritoneal (IP) injection of fish (into the fish belly) is ensuring the positioning of the needle in the fish. Inaccurate positioning can harm the fish and make the vaccination ineffective. Known positioning systems for intra-peritoneal (IP) injection use machine vision systems and actuators to control the needle position in the fish. When such systems are mounted as an end effector on a robotic arm, their mass and connectivity requirements make the robotic system larger, heavier and slower. The vision processing time can also slow down the handling process, keeping the fish out of water longer, which is detrimental to the welfare of the fish.

Complex positioning systems are also more susceptible to failure and require more expensive and complex maintenance procedures.

Summary of invention

It is desirable to provide a robot end effector that overcomes at least some of the abovementioned problems.

According to a first aspect of the present invention, there is provided a robot end effector for fish injection, the robot end effector comprising:

- a suction device operable to lift a fish;

- a fish support, wherein the suction device and fish support are configurable between:

- a first arrangement in which the suction device lifts the fish; and

- a second arrangement in which the fish support extends underneath at least part of the fish to support the fish; and

- a fish injection device operable to inject the fish when supported by the fish support in the second arrangement. Preferably, the end effector further comprises an actuator to adjust the configuration between the first and second arrangements.

Preferably, the suction device is operable to place the fish on to the fish support.

Preferably, the suction device is operable to lift the fish up by sucking from above the fish.

Preferably, the fish support comprises a perforated fish slice.

Preferably, the suction device and fish support are configurable between the first and second arrangements by a relative rigid motion.

Preferably, the fish support comprises a pair of members shaped to engage with the fish.

Preferably, the pair of members are moved towards each other into the second arrangement to support the fish.

Preferably, the pair of members are moved towards each other by a scissor mechanism.

Preferably, the scissor mechanism is driven by a screw jack.

Preferably, the fish support comprises a convex surface to engage with the fish.

Preferably, the suction device and fish support are configurable between the first arrangement and second arrangement by moving the fish support around a pivot in a scooping motion to cradle the fish with a leading portion of the convex surface being further from the pivot than a trailing portion of the convex surface.

Preferably, the end effector further comprises an alignment guide operable to guide the fish injection device and fish into alignment for intra-peritoneal injection of the fish. Preferably, the alignment guide is operable to guide the fish injection device and fish into alignment by engagement of the alignment guide with the fish's body. Preferably, the alignment guide is biased to engage with the fish.

Preferably, the alignment guide is biased by gravity to engage with the fish.

Preferably, the alignment guide is operable to guide the fish injection device and fish into alignment responsive to force feedback from contact of the alignment guide with the fish's body.

Alternatively, the alignment guide is operable to guide the fish injection device and fish into alignment by engagement of the alignment guide with the fish support.

Preferably, the alignment guide is operable to guide the fish injection device and fish into alignment by engagement of the alignment guide with an extension of the suction device. Preferably, the fish injection device and alignment guide are fixed together in an assembly.

Preferably, the alignment guide comprises the fish support. According to a second aspect of the present invention, there is provided a method of operating a robot end effector for fish injection comprising:

- configuring a suction device and a fish support in a first arrangement;

- lifting a fish with the suction device;

- configuring the suction device and fish support in a second arrangement in which the fish support extends underneath at least part of the fish to support the fish; and

- injecting the fish when supported by the fish support in the second arrangement. Preferably, the method further comprises placing the fish on to the fish support using the suction device.

Preferably, the method further comprises guiding a fish injection device and fish into alignment for intra-peritoneal injection of the fish.

Preferably, the method further comprises guiding the fish injection device and fish into alignment for intra-peritoneal injection of the fish by engagement of the alignment guide with the fish's body.

Preferably, the method further comprises biasing the alignment guide to engage with the fish.

Preferably, the method further comprises biasing the alignment guide to engage with the fish by gravity.

Preferably, the method further comprises guiding the fish injection device and fish into alignment responsive to force feedback from contact of the alignment guide with the fish's body.

Alternatively, the method further comprises guiding the fish injection device and fish into alignment by engagement of the alignment guide with the fish support.

Preferably, the method further comprises guiding the fish injection device and fish into alignment by engagement of an alignment guide with an extension of the suction device.

Brief description of drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the drawings, in which:

Figure 1 illustrates, in schematic form, a robot end effector in accordance with an embodiment of the present invention. Figure 2 illustrates, in schematic form, a robot end effector in accordance with another embodiment of the present invention. Figure 3 illustrates, in schematic form, the robot end effector of Figure 2 at three stages of operation, in accordance with an embodiment of the present invention.

Figure 4 illustrates, in schematic form, a robot end effector in accordance with another embodiment of the present invention.

Figure 5 illustrates, in schematic form, the robot end effector of Figure 4 at three stages of operation, in accordance with another embodiment of the present invention. Figure 6 illustrates, in schematic form, a robot end effector in accordance with another embodiment of the present invention.

Figure 7 illustrates, in schematic form, the robot end effector of Figure 6 at three stages of operation, in accordance with another embodiment of the present invention.

Figure 8 illustrates, in schematic form, a robot end effector in accordance with another example of the present invention. Figure 9 is a flowchart of operation of a robot end effector, in accordance with embodiments of the present invention.

Description of embodiments Embodiments provide a robot end effector (End of Arm Tool, EOAT) that can pick anesthetised fish up at any orientation using suction, inject vaccine intra-peritoneal (IP) (belly) and/or intra-muscular (IM), whilst cradling the fish using a “fish slice” so as to carry out this process gently and at high speed. Intra-Muscular injection may be anywhere on fish where there is muscle. In the examples described herein the intra- muscular injection is in the back, but other vaccines may be required elsewhere, particularly for different species. The fish slice is a support that is positioned under the fish after the fish has been picked up by suction.

The end effector is directed to the correct location by moving the robotic arm(s) after coordinates are passed to the robot from the onboard vision system. This corresponds to steps 902 and 904 in Figure 9. The fish is typically picked up from a conveyor belt, which may be moving, with the movement being tracked by the robotic arm. In embodiments, the end effector uses suction and a support such as a fish slice, to lift and cradle the fish in a manner which prioritises the fish welfare. The end effector may have a 360° range of motion about the Z-axis (world coordinates) which allows the robot to pick up the fish in any orientation and then place the fish in any orientation after injection.

Embodiments may use both suction and the fish support to hold the fish during injection. However, other embodiments are operable to turn the suction off once the fish support is in place. This reduces potential injury to the fish.

Embodiments may have an alignment guide which ensures the IP injection is on the centre line of the fish belly. The alignment guide may gently slide above and below the fish as it is held on its side, as the alignment guide is pushed towards the fish belly. This provides a simple, low-mass mechanism that allows the robot to be made smaller.

Figure 1 illustrates, in schematic form, a robot end effector in accordance with an embodiment of the present invention.

Figure 1a shows an end effector 100 at a stage of operation where a fish has been picked up. A robotic arm interface 102 is shaped to allow connection of the end effector to a robotic arm (not shown). The interface 102 is part of a frame which supports different components of the end effector. An intra-muscular (IM) injector actuator 104 is provided to actuate a needle (112 in Figure 1 b) into the muscle of a fish when held in the end effector. A suction device 132 is operable to lift the fish (134 in Figure 1 b). Suction device 132 is operable to lift the fish up and to place it on the fish support 136 by moving vertically with reference to Figure 1b under the influence of suction device actuator 108.

The fish support 136 in this example is a fish slice, which is perforated with slots to allow water to drain from the fish when supported by the fish slice. In this example the perforations extend all the way to the edge of the fish slice to form a comb or tooth structure. The suction device 132 and fish support 136 are configurable between a first arrangement 100 as shown in Figures 1a and 1 b, in which the suction device 132 lifts the fish 134, and a second arrangement (not shown in Figure 1 but illustrated in Figures 2 to 7), in which the fish support 136 extends underneath the fish 134 to support the fish.

A fish injection device 118 (shown in Figure 1b) is operable to inject the fish when supported by the fish support 136 in the second arrangement. The suction device 132 is operable to lift the fish 134 up by sucking from above the fish. In this embodiment, the suction device 132 and fish support 136 are configurable between the first and second arrangements by a relative rigid motion comprising relative translations along a combination of two linear paths. A fish support actuator 114 adjusts the configuration between the first and second arrangements by moving the fish support 136 horizontally with reference to Figure 1b. A second actuator 106 adjusts the configuration between the first and second arrangements by moving the fish support 136 vertically with reference to Figure 1 b.

The fish injection device 118 is operable to inject the fish 134 with a needle (not shown) which is moved horizontally with reference to Figure 1b by the intra- peritoneal injector actuator 110. Accurate positioning of the needle in the fish is provided by the alignment guide 124, which is operable to guide the fish injection device 118 and fish 134 into alignment for the intra-peritoneal injection of the fish. In embodiments described herein, the alignment guide 124, 324, 524 is operable to guide the fish injection device because it is moveable relative to the fish and shaped to engage with the fish or complementary hardware. In this embodiment, the alignment guide 124 guides the alignment by engagement with the fish's body. The alignment guide 124 in this example is shaped like rabbit ears, viewed from the direction illustrated in Figure 1b, with the fish being engaged in between the pair of "rabbit ears". The alignment guide 124 is biased to engage with the fish 134. An alignment guide and IP injection device assembly actuator 116 moves the alignment guide and injection device assembly horizontally with respect to Figure 1b. When the alignment guide 124 contacts the fish it is allowed to slide (relative to the actuator) up against gravity. This is achieved by mounting the IP injector 118 and alignment guide 124 assembly onto the actuator 116 with a set of rollers 120 engaged with a vertical rail 122 and another set of rollers 126 engaged with a diagonally sloping rail 128. The rails are fixed to or part of a sub-frame moved by the actuator 116. The rollers are fixed to a sub-chassis for the IP injector 118 and alignment guide 124 assembly.

Figure 2 illustrates, in schematic form, a robot end effector in accordance with another embodiment of the present invention. Figure 2 shows an end effector 370 at a stage of operation where a fish (not shown) has been picked up. Figure 2 is a projection that should be viewed with Figures 3a to 3c, to help interpretation of the side elevation drawings of Figures 3a to 3c. The features labelled with reference numerals in Figure 2 are shared with Figures 3a to 3c.

Figure 3 illustrates, in schematic form, the robot end effector of Figure 2 at three stages of operation. Like the embodiment described with reference to Figure 1 , this embodiment uses passive hardware-centric centralisation techniques to locate the intra-peritoneal injection target site.

Specially shaped rabbit ears 324 that are incorporated into an IP injector device 318 assembly engage with the complementary surfaces located on a suction device chassis 340 and the end of the fish support 336.

With reference to Figures 2 and 3, a robotic arm interface 302 is shaped to allow connection of the end effector to a robotic arm (not shown). The interface 302 is part of a frame which supports different components of the end effector. An intra muscular (IM) injector actuator (not shown) may be provided to push a needle into the muscle of a fish when held in the end effector, as described with reference to Figure 1.

A suction device 332 is operable to lift the fish 334. Suction device 332 is operable to lift the fish up and to place it on the fish support 336 by moving vertically under the influence of suction device actuator 308.

The fish support 336 in this example is a fish slice, which is perforated with slots to allow water to drain from the fish when supported by the fish slice. The suction device 332 and fish support 336 are configurable between a first arrangement 350 as shown in Figure 3a, in which the suction device 332 lifts the fish 334, and a second arrangement 370 as shown in Figure 3c, in which the fish support 336 extends underneath the fish 334 to support the fish.

Figure 3a illustrates the "sucker down" stage 350 of operation of the end effector. This corresponds to steps 906 and 908 in Figure 9.

At the start of this stage, a single-action pneumatic fish support actuator 314 exerts a linear horizontal force at the top of the fish support 336 causing it to swing 337 back and up around the upper hinge 338.

The suction for the suction device 332 is turned on. This corresponds to step 906 in Figure 9. The suction device 332 is operable to lift the fish 334 up by sucking from above the fish. The single-action, spring-loaded pneumatic actuator 308 lifts the suction device 332 and attached fish 334. In this example, the suction device 332 comprises a set of four suction cups mounted on a chassis.

Figure 3b illustrates the "sucker up, move support" intermediate stage 360 of operation of the end effector. This corresponds to steps 910 and 912 described with reference to Figure 9.

The fish support actuator 314 releases when the suction device 332 is raised, and the fish support 336 swings 337 back down, as shown in Figure 3b, to support the base of the fish during injection at the stage 370 illustrated in Figure 3c. After the fish support 336 rotates around the hinge 338, the pneumatic suction device actuator 308 releases, gently sandwiching the fish between the suction cups 332 and the fish support 336 platform.

Thus, in this embodiment, the suction device 332 and fish support 336 are configurable between the first 350 and second 370 arrangements, via the intermediate stage 360 shown in Figure 3b. The reconfiguration is done by combination of a relative translation 333 of the suction device 332 along a linear path and a relative rotation 337 of the fish support around hinge 338. Thus, if both actuators 314, 308 operate at once, the suction device 332 and fish support 336 may configurable between the first and second arrangements by a relative rigid motion along a curved path. In general, rigid motions comprise combinations of translations and rotations.

Figure 3c illustrates the "needle centralized" stage 370 of operation of the end effector. This corresponds to step 914 in Figure 9.

Accurate positioning of the needle in the fish is provided by the operation of the alignment guide 324, which is shaped to guide the fish injection device 318 and fish 334 into alignment for the intra-peritoneal injection of the fish. In this embodiment, the alignment guide 324 guides the alignment by engagement with both the suction device chassis 340 and the fish support 336, as shown in Figures 3b and 3c. In other embodiments (not shown), the alignment guide 324 guides the alignment by engagement with one or other of the suction device chassis 340 and the fish support 336. The alignment guide 324 in this example is shaped like a “V” from the direction illustrated in Figures 3a to 3c, with the end of suction device chassis 340 and the end of fish support 336 being engaged in between the prongs of the of "V". The alignment guide 324 is biased to engage with the suction device chassis 340 and the fish support 336. An alignment guide and IP injection device actuator 316 drives the alignment guide 324 and injection device 318 assembly down a gradient, diagonally with respect to Figures 3a to 3c, so that the alignment guide 324 centralises around the complementary hardware (suction chassis 340 and fish support 336 platform). This is achieved by mounting the IP injector 318 and alignment guide 324 assembly onto the frame with a pair of annular bearings 326 engaged with diagonally sloping rods 328 that are fixed to a sub-chassis for the IP injector 318 and alignment guide 324 assembly. The annular bearings 326 are fixed to the frame along with the alignment guide and IP injection device actuator 316.

Now that the fish 334 is safely cradled by the fish slice 336, suction may be switched off, while the fish is subject to the forces of movement of the robotic arm and injection. This corresponds to step 916 in Figure 9.

For injection of the fish, corresponding to 918 and 922 in Figure 9, the linear actuator of the intra-peritoneal injector actuator 310 drives the needle 320 into the belly of the fish. This may be done while moving and/or orientating the end effector by activating the robotic arm for the purpose of sorting the fish and/or positioning it within the fish handling path. This corresponds to step 920 in Figure 9.

The fish injection device 318 is thus operable to inject the fish with needle 320 when supported by the fish support 336 in the second arrangement 370. The needle 320 is moved horizontally by the intra-peritoneal injector actuator 310, with respect to Figure 3c.

Release of the fish is performed by reversing the sequence of the steps illustrated in Figures 3a and 3b. The intra-peritoneal injector actuator 310 retracts the needle 320. The alignment guide 324 disengages from the centralising complementary hardware (suction chassis 340 and fish support 336 platform). These steps correspond to step 924 in Figure 9.

If the suction had been switched off, it is switched on. This corresponds to step 926 in Figure 9. The fish support actuator 314 pushes 337 the fish support 336 out of the way of the range of motion 333 of the fish 334 when lifted or lowered by the suction device 332. This corresponds to step 928 in Figure 9.

The suction device 332 is then free to lower the fish 334 to the “sucker down” position 350 shown in Figure 3a before turning the suction off and the fish is released. This corresponds to step 930 in Figure 9. Alternatively, the fish may be released as soon as the fish support actuator 314 pushes 337 the fish support 336 out of the way, without lowering the suction device 332.

Figure 4 illustrates, in schematic projection form, a robot end effector in accordance with another embodiment of the present invention. Figure 4 shows an end effector 570 at a stage of operation where a fish has been picked up. Figure 4 is a projection that should be viewed with Figures 5a to 5c, to help interpretation of the side elevation drawings of Figures 5a to 5c. The features labelled with reference numerals in Figure 4 are shared with Figures 5a to 5c.

Figure 5 illustrates, in schematic form, the robot end effector of Figure 4 at three stages of operation. This embodiment uses a screw jack mechanism to semi-actively centralize the needle on the fish's belly. Since the injection device is fixed to the alignment guide, only a single actuator is required to achieve centralisation of the needle. Furthermore, the alignment guide acts as jaws to hold the fish, without the need for suction. Although a “screw jack” is used here, another type of linear motor/actuator may be used.

A pair of specially shaped members 524, one of which is incorporated with an IP injector device 518 assembly, engage with the fish 534. The fish is gently grasped by its belly and back when it is on its side, as shown in Figures 4 and 5.

With reference to Figures 4 and 5, a robotic arm interface 502 is shaped to allow connection of the end effector to a robotic arm (not shown). The interface 502 is part of a frame which supports different components of the end effector. An intra muscular (IM) injector actuator (not shown) may be provided to push a needle into the muscle of a fish when held in the end effector, as described with reference to Figure 1.

A suction device 532 is operable to lift the fish 534. Suction device 532 is operable to lift the fish up for placement on upward facing surfaces of a fish support 524, by moving vertically under the influence of suction device actuator 508. Each lower part of fish support 524 in this example is a pair of fish slices, which are perforated with slots to allow water to drain from the fish when supported by the fish slices. In this example the perforations extend all the way to the lower edge of the fish slices to form a comb or tooth structure. The suction device 532 and fish support 524 are configurable between a first arrangement 550 as shown in Figure 5a, in which the suction device 532 lifts the fish 534, and a second arrangement 570 as shown in Figure 5c, in which the fish support 524 extends underneath at least part of the fish 534 to support the fish.

Figure 5a illustrates the "sucker down" stage 550 of operation of the end effector. This corresponds to step 908 in Figure 9. At this stage, a screw jack actuator 516 has moved apart 525 the pair of fish slices of the fish support 524.

At the beginning of this stage, the suction for the suction device 532 is turned on.

This corresponds to step 906 in Figure 9. In this example, the suction device 532 comprises a set of four suction cups mounted on a chassis. The two single-action, spring-loaded pneumatic actuator 508 control the synchronised release of the suction device chassis allowing the suction device 532 to drop between the fish supports 524 to pick up fish. The pneumatic cylinders 508 activate to lift the fish while the levers 548 are fully contracted and the fish supports 524 are at their widest- apart position.

The suction device 532 is thus operable to lift 533 the fish 534 up by sucking from above the fish. The actuators 508 lifts the suction device 532 and attached fish 534.

Figure 5b illustrates the "sucker up, move support" intermediate stage 560 of operation of the end effector. This corresponds to steps 910 and 912 described with reference to Figure 9.

The fish support screw jack actuator 516 operates when the suction device remains raised by, and static relative to, the suction device actuator 508. The fish support screw jack actuator 516 operates provide two simultaneous actions. It operates to lower 517 the suction device 532, relative to the interface 502. Furthermore, it operates to lower, relative to the interface 502, and bring together 525 the pair of fish slices making up the fish support 524. Because the rate of vertical descent of the suction device 532 is greater than the rate of vertical descent of the fish support 524, the parts come together to gently cradle the fish in the fish support 524, while also holding the fish by the suction device 532.

In more detail of this specific example, the motor 516 drives the lead screw (542 in Figure 4) of the screw jack mechanism which enables the simultaneous longitudinal and lateral translation 547 of the jack levers (548, visible in Figure 4 and Figure 5c) and sliding rails 549. Consequently, the fish slices of the fish support 524 follow a trajectory that is approximately diagonal.

This mechanism may be semi-active as the motor 516 may receive information (via a control system) about fish height from a vision system or may receive force feedback from the fish support 524 . This enables accurate centralisation of the needle (dotted line 520 in Figure 5c) at the fish belly while mitigating any potential crushing.

There is a correlation between the lengths of the various levers 548 and the degree of longitudinal and lateral actuation 525 experienced by the pair of fish slices of the fish support 524. The lever lengths also determine the linear or parabolic nature of the fish support’s trajectory. As such, the mechanism can be finely tuned to accommodate most types of fish.

After the suction device 532 and the fish support 524 move 517, 525 down and together, as shown in Figure 5b, they support the base of the fish 534 during injection at the stage 570 illustrated in Figure 5c. The fish 534 is gently sandwiched between the suction cups of the suction device 532 and the pair of inner upward- facing fish slice surfaces of the fish support 524.

Thus, in this embodiment, the suction device 532 and fish support 524 are configurable between the first 550 and second 570 arrangements, via the intermediate stage 560 shown in Figure 5b. The reconfiguration is done by combination of relative translations 533 and 517 of the suction device 532 along a linear path and a relative translation 525 of the fish support 524. Alternatively, depending on the lever lengths, the suction device 532 and fish support 524 may configurable between the first and second arrangements by a relative rigid motion along a curved path.

Figure 5c illustrates the "needle centralized" stage 570 of operation of the end effector. This corresponds to step 914 in Figure 9.

As discussed above, the fish support screw jack actuator 516 operates provide two simultaneous actions. It operates to lower 517 the suction device 532, relative to the interface 502. Furthermore, it operates to lower, relative to the interface 502, and bring together 525 the pair of fish slices making up the fish support 524. These actions, in combination with the “rabbit ears” shape of the fish support 524, cause the injection device 518 to centralise around the body of the supported fish 534.

Similar to the embodiment described with reference to Figure 1 , accurate positioning of the needle in the fish is thus provided by the fish support 524, which has a dual function, also operating as an alignment guide. Therefore, the fish support 524 will now be referred to as a combined fish support and alignment guide. It is shaped to guide the fish injection device 518 and fish 534 into alignment for the intra-peritoneal injection of the fish. In this embodiment, the combined fish support and alignment guide 524 guides the alignment by engagement with the fish 534, as shown in Figures 5b and 5c. The combined fish support and alignment guide 524 in this example is shaped like a “V” from the direction illustrated in Figures 5a to 5c, with the fish 534 being engaged in between the prongs of the of "V". The combined fish support and alignment guide 524 is biased to engage with the fish 534 by the actuator 516 of the jack screw mechanism. The IP injector 518 is fixed to one side of the combined fish support and alignment guide 524.

Now that the fish is safely cradled by the fish slices 524, suction may be switched off, while the fish is subject to the forces of movement of the robotic arm and injection. This corresponds to step 916 in Figure 9.

For injection of the fish, corresponding to steps 918 and 922 in Figure 9, the linear actuator of the intra-peritoneal injector actuator 510 drives the needle into the belly of the fish. This may be done while moving and/or orientating the end effector by activating the robotic arm for the purpose of sorting the fish and/or positioning it within the fish handling path. This corresponds to step 920 in Figure 9.

The fish injection device 518 is thus operable to inject the fish with needle (shown by dotted line 520 in Figure 5c) when supported by the combined fish support and alignment guide 524 in the second arrangement 570. With reference to Figure 5c, the needle 520 is moved horizontally by the intra-peritoneal injector actuator 510. Alternatively, the movement may be non-horizontal if the fish is held at an angle or if the end effector is tilted.

Release of the fish is performed by reversing the sequence of the steps illustrated in Figures 5a and 5b. The intra-peritoneal injector actuator 510 retracts the injection device 518 and needle 520. These steps correspond to step 924 in Figure 9.

If the suction had been switched off, it is switched on. This corresponds to step 926 in Figure 9. The fish support screw jack actuator 516 operates provide two simultaneous actions. It operates to raise 517 the suction device 532, relative to the interface 502. Furthermore, it operates to raise, relative to the interface 502, and separate 525 the pair of fish slices making up the combined fish support and alignment guide 524. The combined fish support and alignment guide 524 disengages from the fish 534. This corresponds to step 928 in Figure 9.

The suction device 532 is then free to lower the fish 534 to the “sucker down” position 550 shown in Figure 5a before turning the suction off and the fish is released. This corresponds to step 930 in Figure 9. Alternatively, the fish may be released as soon as the fish support screw jack actuator 516 opens 525 the jaws of the combined fish support and alignment guide 524 far apart enough to let the fish drop, without lowering the suction device 532.

Figure 6 illustrates, in schematic form, a robot end effector in accordance with another embodiment of the present invention. Figure 6 shows an end effector 770 at a stage of operation where a fish (not shown) has been picked up. Figure 6 is a projection that should be viewed with Figures 7a to 7c, to help interpretation of the side elevation drawings of Figures 7a to 7c. The features labelled with reference numerals in Figure 6 are shared with Figures 7a to 7c.

Figure 7 illustrates, in schematic form, the robot end effector of Figure 6 at three stages of operation.

With reference to Figures 6 and 7, a robotic arm interface 702 is shaped to allow connection of the end effector to a robotic arm (not shown). The interface 702 is part of a frame which supports different components of the end effector. An intra muscular (IM) injector actuator (not shown) may be provided to push a needle into the muscle of a fish when held in the end effector, as described with reference to Figure 1.

A suction device 732 is operable to lift the fish 734. Suction device 732 is operable to lift the fish up and to place it on the fish support 736 by moving vertically under the influence of suction device actuator 708.

The fish support 736 in this example is a fish slice, which is perforated with slots to allow water to drain from the fish when supported by the fish slice. In this example the perforations extend all the way to the edge of the fish slice to form a comb or tooth structure.

The suction device 732 and fish support 736 are configurable between a first arrangement 750 as shown in Figure 7a, in which the suction device 732 lifts the fish 734, and a second arrangement 770 as shown in Figure 7c, in which the fish support 736 extends underneath the fish 734 to support the fish.

Figure 7a illustrates the "sucker down" stage 750 of operation of the end effector. This corresponds to step 908 in Figure 9.

At this stage, a fish support actuator 714 exerts a torque at a shaft at the top of the fish support 736 causing it to rotate 737 around the rotor of the actuator 714 and the attached shaft of the fish support 736. The suction for the suction device 732 is turned on. This corresponds to step 906 in Figure 9. The suction device 732 is operable to lift the fish 734 up by sucking from above the fish. The single-action, spring-loaded pneumatic actuator 708 lifts the suction device 732 and attached fish 734. In this example, the suction device 732 comprises a set of four suction cups mounted on a chassis.

Figure 7b illustrates the "sucker up, move support" intermediate stage 760 of operation of the end effector. This corresponds to steps 910 and 912 described with reference to Figure 9.

The fish support actuator 714 applies the torque when the suction device has been raised, and the fish support 736 rotates 737 round, as shown in Figure 7b, ready to support the base of the fish during injection at the stage 770 illustrated in Figure 7c.

After the fish support 736 rotates around the rotor of the actuator 714, the pneumatic suction device actuator 708 releases, gently sandwiching the fish between the suction cups 732 and the fish support 736 platform, in preparation for needle penetration.

In this embodiment, the suction device 732 and fish support 736 are configurable between the first 750 and second 770 arrangements, via the intermediate stage 760 shown in Figure 7b. The reconfiguration is done by combination of a relative translation 733 of the suction device 732 along a linear path and a relative rotation 737 of the fish support around the rotor of the actuator 714. Thus, if both actuators 714, 708 operate at once, the suction device 732 and fish support 736 may configurable between the first and second arrangements by a relative rigid motion along a curved path.

Figure 7c illustrates the "needle centralized" stage 770 of operation of the end effector. This corresponds to step 914 in Figure 9.

This embodiment uses active centralisation to locate the intra-peritoneal injection target site on the fish 734. By using a motor 716 to control the z-axis (vertical in Figure 7) translation 721 of the needle, the end effector is able to actively find the centre of the fish’s belly given the side-to-side width of the fish as provided by a sensor on the suction device actuator 708 and/or a vision system (not shown). The vision system calculates the side-to-side width of the fish using a dedicated algorithm and provides this information to the controller of the motor 716. The motor drives a lead screw 723 that vertically translates 721 the needle chassis 724 so that the needle 720 is aligned with the midpoint of the fish’s belly. By using another separate motor arrangement (not shown) to control the y-axis translation of the needle (into and out of the paper with reference to Figure 7c), the end effector is able to actively inject the centre of the fish’s belly given the anterior-to-posterior length of the fish as provided by the vision system.

Now that the fish is safely cradled by the fish slice, suction may be switched off, while the fish is subject to the forces of movement of the robotic arm and injection. This corresponds to steps 916 to 920 in Figure 9.

For injection of the fish, corresponding to steps 918 and 822 in Figure 9, the linear actuator of the intra-peritoneal injector actuator 710 drives the needle 720 into the belly of the fish. This may be done while moving and/or orientating the end effector by activating the robotic arm for the purpose of sorting the fish and/or positioning it within the fish handling path. This corresponds to step 920 in Figure 9.

The fish injection device 718 is thus operable to inject the fish with needle 720 when supported by the fish support 736 in the second arrangement 770. The needle 720 is moved horizontally by the intra-peritoneal injector actuator 710.

Release of the fish is performed by reversing the sequence of the steps illustrated in Figures 7a and 7b. The intra-peritoneal injector actuator 710 retracts the needle 720. This step corresponds to step 924 in Figure 9.

If the suction had been switched off, it is switched on. This corresponds to step 926 in Figure 9. The suction device 732 raises the fish 734 clear of the fish support 736. The fish support actuator 714 rotates 737 the fish support 736 out of the way of the full range of motion 733 of the fish 734 when further lowered by the suction device 732. This corresponds to step 928 in Figure 9. The suction device 732 is then free to lower the fish 734 to the “sucker down” position 750 shown in Figure 7a before turning the suction off and the fish is released. This corresponds to step 930 in Figure 9. Alternatively, the fish may be released as soon as the fish support actuator 714 rotates 737 the fish support 736 out of the way, without lowering the suction device 732.

Figure 8a shows an end effector 800 at a stage of operation where a fish has been picked up. A robotic arm interface (not shown) is shaped to allow connection of the end effector to a robotic arm (not shown). The interface is joined to a frame 802 which supports different components of the end effector. An intra-muscular (IM) injector actuator 804 is provided to actuate a needle 842 (labelled in Figure 8b) into the muscle of a fish when held in the end effector. A suction device 832 is operable to lift the fish (834 in Figure 8b). Suction device 832 is operable to lift the fish up by moving up vertically 833 with reference to Figure 8b under the influence of suction device actuator 808. Suction device 832 may also be operable to place the fish on the fish support 836 by moving down vertically 833 with reference to Figure 8b under the influence of suction device actuator 808.

The fish support in this example has two sections. In other variants (not shown) the fish support may be one or more fish slice, perforated with slots to allow water to drain from the fish when supported by the fish slice. For example the perforations may extend all the way to the edge of the fish slice to form a comb or tooth structure.

The suction device 832 and fish support 836 are configurable between a first arrangement (not shown in Figure, 8 but similar to that shown in Figure 3a) with the fish support 836 swung out of the way to the side, in which the suction device 832 lifts the fish 834, and a second arrangement (as shown in Figure 8), in which the fish support 836 extends underneath the fish 834 to support the fish by cradling it.

An intra-peritoneal fish injection device 818 is operable to inject the fish with a needle 844 when supported by the fish support 836 in the second arrangement. The suction device 832 is operable to lift the fish 834 up by sucking from above the fish. The movement of the fish support 836 is similar to that described with reference to Figure 3. At the start of the end effector’s operation, a single-action pneumatic fish support actuator 814 exerts a force at the top of the fish support 836 via actuator rod 840 and pull arm 842 causing fish support 836 to swing 837 back and up around the support pivot 838. The actuator rod 840 is pivotally connected to a pull rod 846 (labelled in Figure 8a). The pull rod 846 is pivotally connected to the top end of pull arm 842. The bottom end of pull arm 842 is pivotally connected 836 to the upper end of the fish support 836.

Next, the suction for the suction device 832 is turned on. This corresponds to step 906 in Figure 9. The suction device 832 is operable to lift the fish 834 up by sucking from above the fish. The single-action, spring-loaded pneumatic actuator 808 lifts the suction device 832 and attached fish 834. In this example, the suction device 832 comprises a set of four suction cups mounted on a chassis.

The fish support actuator 814 releases when the suction device 832 is raised, and the fish support 836 swings 837 around and under the fish to support the base of the fish during injection.

After the fish support 836 rotates around the pivot 838, the pneumatic suction device actuator 808 may release, gently sandwiching the fish between the suction cups 832 and the fish support 836 platform. In this embodiment, the suction device 832 and fish support 836 are thus configurable between the first and second arrangements by combination of a relative translation 833 of the suction device 832 along a linear path and a relative rotation 837 of the fish support around pivot 838. Thus, if both actuators 814, 808 operate at once, the suction device 832 and fish support 836 may configurable between the first and second arrangements by a relative rigid motion along a curved path. In general, rigid motions comprise combinations of translations and rotations. The intra-peritoneal fish injection device 818 is operable to inject the fish 834 with a needle 844 which is moved horizontally with reference to Figure 8b by the intra- peritoneal injector actuator 810.

Accurate positioning of the intra-peritoneal needle 844 in the fish may be assisted by a machine vision system and an intra-peritoneal injection device assembly actuator 816 that moves the injection device assembly 818 vertically with respect to the fish via lead screw 848.

An alignment guide (not shown), may be operable to guide the fish injection device 818 and fish 834 into alignment for the intra-peritoneal injection of the fish. Similar to embodiments described herein, the alignment guide may be operable to guide the fish injection device because it is moveable relative to the fish and shaped to engage with the fish or complementary hardware.

The intra-muscularfish injection device 800 is operable to inject the fish 834 with an intra-muscular needle 842 which is moved by the intra-peritoneal injector actuator 804.

Accurate positioning of the intra-muscular needle 842 in the fish may be assisted by a machine vision system and another actuator (not shown) that moves the intra muscular fish injection device 800 along rails on the frame 802.

The example described with reference to Figure 8 raises the support into contact with the fish in a similar way to that described with reference to Figure 1. But this example does it in one motion (with one actuator 814, rather than two 106, 114) at the same time as swinging the fish slice in from the side in a way similar to that described with reference to Figures 2 and 3. The location of the fish support pivot 838 and the convex shape of the fish support 836 allow a simple mechanism and an effective engagement of the fish support to securely cradle the fish. The convex surface is not only shaped to fit well around the fish, but also it is arranged with the pivot to scoop under the fish to cradle it. Thus the suction device and fish support are configurable between the first arrangement and second arrangement by moving the fish support around a pivot in a scooping motion to cradle the fish with a leading portion of the convex surface being further from the pivot than a trailing portion of the convex surface. This shape and scooping motion is like a cupped hand rotating around a wrist to scoop under the fish and cradle it. With this arrangement, a relatively small range of motion is needed to support the fish, which allows for a smaller, lighter end effector. This means the robotic system may be faster and lighter and more mobile.

Figure 9 is a flowchart of operation of a robot end effector, in accordance with embodiments of the present invention.

902: The control system receives coordinates of the (stationary or moving) fish.

904: The robot moves and orientates the end effector above the fish.

906: The suction for the suction device is turned on, for example by turning on a pump or by opening a valve.

908: The suction cups of the suction device are lowered down to contact the fish.

910: The fish is lifted by moving the suction device up.

912: The fish support is actuated. The fish may be lowered onto the support by the suction cups.

914: The needle is centralised.

916: The suction may be switched off, or reduced in strength. This and the previous step may be reversed.

918: The injectors are actuated.

920: At the same time, the end effector (EOAT) may be moved and oriented.

922: The fish is injected. 924: The injectors are deactuated and the centralization mechanism, if physically engaged, is disengaged. 926: The suction is turned on.

928: The fish support is retracted.

930: The suction is turned off.

Advantages provided by embodiments are as follows:

Passive methods of centralising IP needle on the fish belly are provided, using simple mechanisms. The likelihood of injury to fish by overuse of suction is reduced, as suction can be switched off or reduced while the fish is cradled in fish slice.

Embodiments reduce costs with simplified robot end effectors, while providing a quality service respecting the fish health and welfare. Embodiments do this by causing less suction damage, with the added support of the slice enabling less suction during movement and injection.

Embodiments facilitate a quality injection process respecting the fish health and welfare. The centralization aspect does this by providing the accurate positioning of rabbit ears in an automated setting but with a simple, reliable, low-mass mechanism. The accurate positioning is kinder to live fish. The low-mass mechanism means less time out of water for the fish and allows a smaller robot, which can be made mobile and modular to put the cost advantage of automation in reach of more customers.