A centering and locking mechanism

Abstract

A centering and locking mechanism, belonging to the mechanical field, includes two picking arms on a turnover box or turnover box assembly picking device; an end effector with a hook head is provided at the lower end of the two picking arms; the end effector includes a centering and locking device located inside the hook head; the centering and locking device includes a vertical piston fitted with a return spring and two horizontal pistons; the vertical piston is a T-shaped structure and is movably disposed inside the hook head; the return spring is fitted on the vertical side of the T-shaped structure; the two horizontal pistons are slidably disposed on both sides of the bottom end of the vertical piston; the bottom end of the vertical piston is connected to the tail end of the two horizontal pistons respectively through two connecting bars; the first end of the two connecting bars is pinned to the bottom end of the vertical piston, forming a first pin contact point; the end of the two connecting bars is pinned to the tail end of the two horizontal pistons respectively, forming a second pin contact point. This mechanism ensures that the end effector can automatically position the center of the recessed handle of the turnover box.

Description

Technical Field

[0001] This invention belongs to the field of cargo loading machinery, and particularly relates to a device and method that allows an end effector to safely grip the center of a recessed handle of a turnover box. Background Technology

[0002] The metrology center is a facility that provides automated calibration lines and intelligent warehousing for all subsidiaries of the State Grid Corporation of China.

[0003] Verified meters and transformers are placed in specially sized, dedicated crates, which are stacked and placed on an electric conveyor belt leading to the loading area.

[0004] Currently, the core operation of the metering center, namely the verification of electricity meters and transformers, is fully automated; verified electricity meters and transformers are placed in customized turnover boxes and sent to the loading area via electric conveyor belts.

[0005] Once these crates reach the end of the conveyor belt, they are manually stacked up to 12 layers high, moved into truck containers, and placed in their target locations. A key task in this process is correctly stacking the crates.

[0006] like Figure 1a and Figure 1b As shown, the crate is made of hard plastic, with the center of the top on both sides of the crate (see...) Figure 1a The area outlined by the black line has two recessed handles 2, and on both sides of the recessed handles, there are two longitudinal inner sidewalls 18.

[0007] Each recessed handle has a sloping top edge 1 extending 5mm outward from the end of the container, forming an extended sloping top edge 3. This sloping top edge allows fingers to bend and hook in, enabling the container to be lifted. The lower edge of this sloping top edge is approximately 5mm from the outer wall of the container, forming the extended width 5 of the sloping top edge. Below this sloping top edge, there is a lower longitudinal space 4, within which there are no other obstructions (vertical height approximately 63mm). The container is designed with a bottom protrusion 20 to prevent the containers from moving when they overlap, which helps maintain the stability of each stack.

[0008] Various automated devices have been widely used in the handling and stacking of turnover boxes to reduce the labor intensity of manual operations.

[0009] The invention patent CN 102662156 B, with an authorization announcement date of December 3, 2014, discloses "a clamping mechanism for electricity meter turnover boxes," including a first arm, a second arm, and an arm tail rod connecting the two on the same side. At least one of the first and second arms is provided with a clamping device for clamping the electricity meter turnover box. This technical solution uses the first arm, second arm, and arm tail rod connecting the two on the same side to form a space for accommodating the turnover box. The clamping action of the clamping device clamps the turnover box, completing the clamping operation for a single turnover box. When it is necessary to place the turnover box, the retraction action of the clamping device separates the turnover box from the electricity meter turnover box clamping mechanism, completing the placement operation. The electricity meter turnover box clamping mechanism realizes the functions of clamping and placing a single electricity meter turnover box. However, this technical solution focuses on the horizontal clamping of a single electricity meter turnover box, and is only applicable to the operation of picking up and putting down a single electricity meter turnover box. It is not applicable to the clamping and moving of multiple electricity meter turnover boxes that have been stacked vertically (also known as electricity meter turnover box groups).

[0010] A utility model patent, authorized on September 24, 2014, with authorization announcement number CN 203845469 U, discloses a "paper turnover box stacking and unstacking device for an automated verification system of electricity meters." The device includes a horizontal transfer mechanism, a lifting device, and a rotatable gripper mechanism. The horizontal transfer mechanism is horizontally mounted on a frame, and the lifting device is vertically connected to the execution end of the horizontal transfer mechanism via its mounting support. The rotatable gripper mechanism consists of a rotary cylinder, a gripper mechanism mounting plate, and multiple gripper mechanisms. The rotary cylinder is mounted at the lower end of the lifting device; the gripper mechanism mounting plate is located at the rotating shaft end of the rotary cylinder, and the multiple gripper mechanisms are distributed below the gripper mechanism mounting plate. This technical solution enables the stacking and unstacking of two adjacent layers of turnover boxes at a certain angle, ensuring the safety and reliability of the paper inbound boxes and their meters on the production line. However, it does not have the function of grabbing, clamping and moving a whole group of turnover boxes (also known as a turnover box stack) composed of multiple turnover boxes stacked vertically.

[0011] How to safely and stably grasp, clamp, and move a group of turnover boxes that are stacked vertically is a technical problem that needs to be solved in practical work.

[0012] A utility model patent, authorized on July 28, 2020, with authorization announcement number CN 211109843 U, discloses "a gripper for a palletizing robot," comprising a fixed base and a gripper mechanism. The fixed base has sliding plates on both sides, which can move relative to the fixed base in opposite directions. The gripper mechanism is mounted on the sliding plates and includes a rotating gripper and a limiting rod. The rotating gripper is rotatably mounted on the sliding plate, while the limiting rod is fixedly mounted on the sliding plate. The rotating gripper is V-shaped. The gripper mechanism also includes a tension spring for resetting the rotating gripper. The fixed base has a drive mechanism for driving the two sliding plates to move in opposite directions. This technical solution provides a gripper for a palletizing robot that can quickly and stably grip, ensuring both high efficiency and stability during palletizing. However, this technical solution still relies on mechanical components to "clamp" a single turnover box (see Figure 5 in its instruction manual), and is not suitable for scenarios where a group of turnover boxes consisting of multiple turnover boxes stacked vertically is grabbed, clamped, and moved. Summary of the Invention

[0013] The technical problem to be solved by this invention is to provide a centering and locking mechanism. By setting end effectors at the ends of the two picking arms of the picking device, and using a centering and locking mechanism, through a vertical piston and a set of return springs, the lifting or lowering of the end effectors can easily achieve the lateral extension or retraction of the two lateral pistons. This enables automatic centering, automatic positioning, stable clamping, and automatic release at the end of the picking arms, ensuring that the end effectors can automatically position themselves at the center of the recessed handle of the turnover box and firmly grip the recessed handle.

[0014] The technical solution of the present invention is: to provide a centering and locking mechanism, comprising two picking arms disposed on a turnover box or turnover box assembly picking device, characterized in that:

[0015] At the lower end of each of the two pickup arms, there is an end effector with a hook head, which is used to extend into the recessed handle of the bottom turnover box; the end effector includes a centering and locking device located inside the hook head; the centering and locking device includes a vertical piston fitted with a return spring and two horizontal pistons.

[0016] The vertical piston is a T-shaped structure that can be moved up and down inside the hook head; its return spring is fitted on the vertical side of the T-shaped structure; two horizontal pistons are respectively arranged on both sides of the bottom end of the vertical piston that can slide laterally; the bottom end of the vertical piston is connected to the tail end of the two horizontal pistons respectively through two connecting strips; the first end of the two connecting strips is pinned to the bottom end of the vertical piston to form a first pin joint; the end of the two connecting strips is pinned to the tail end of the two horizontal pistons to form a second pin joint.

[0017] When it is necessary to pick up a turnover box or turnover box group, the picking arm drives the end effector into the recessed handle and moves upward. The top of the vertical piston moves downward under the pressure of the recessed handle, the first pin contact point descends, and the two horizontal pistons are pushed outward / extended by the two connecting bars respectively, so as to realize the automatic centering and automatic clamping function of the end effector.

[0018] When it is necessary to release the turnover box or turnover box group, the picking arm descends, and under the action of the return spring, the vertical piston moves upward, the first pin contact rises, driving the two horizontal pistons to retract inward, and the end effector disengages from the recessed handle, realizing the automatic release function of the end effector in position.

[0019] Specifically, the two transverse pistons are symmetrically arranged on both sides of the vertical piston, with the vertical side of the T-shaped structure of the vertical piston as the axis.

[0020] Furthermore, the two transverse pistons are arranged coaxially, with the center line of the vertical side of the T-shaped structure of the vertical piston as the axis of symmetry, and are arranged laterally symmetrically on both sides of the bottom end of the vertical side of the vertical piston.

[0021] Specifically, the longitudinal position of the first pin contact is higher than the longitudinal position of the second pin contact.

[0022] Once both lateral pistons have contacted the two inner walls of the recessed handle, the end effector will stop advancing upwards within the recessed handle.

[0023] If one of the two lateral pistons first contacts the inner wall of its corresponding recessed handle of the storage box, the end effector will continue to move upward so that the other lateral piston can also reach the inner wall of its corresponding recessed handle of the storage box, thereby ensuring that the outer center of the end effector coincides with the center of the recessed handle.

[0024] Furthermore, the centering and locking mechanism operates according to the following steps:

[0025] 1) The end effector enters the space below the recessed handle;

[0026] 2) The end effector moves upward until the bottom edge of the recessed handle's inclined top edge contacts the top of the vertical piston of the centering and locking device;

[0027] 3) As the end effector continues to move upward, the vertical piston of the centering and locking device is pressed down by the bottom edge of the inclined top edge. The downward movement of the vertical piston of the centering and locking device is converted into a lateral force, which pushes the two lateral pistons on both sides of the end effector outward.

[0028] 4) If only one lateral piston contacts its corresponding inner wall, the end effector will continue to move upward until both lateral pistons contact their inner walls, and the longitudinal centerline of the end effector coincides with the longitudinal centerline of the recessed handle or the turnover box.

[0029] 5) The lateral pressure of the lateral piston on the inner wall locks the end effector to the turnover box, thereby allowing the turnover box to be safely picked up and placed in place;

[0030] 6) Once the turnover box is in place, the end effector will lower so that it can be removed from the recessed handle, during which time the vertical piston of the centering locking device will return to its original position.

[0031] Specifically, the centering and locking mechanism utilizes the lifting or lowering of the end effector to achieve the lateral extension or retraction of the two lateral pistons, thereby realizing the functions of automatic centering, automatic positioning, stable clamping, and automatic release at the end of the picking arm. This ensures that the end effector can automatically position the center of the recessed handle of the turnover box and can firmly grasp the recessed handle of the turnover box.

[0032] Furthermore, the bottom end of the vertical piston is connected to the tail ends of the two horizontal pistons via two connecting bars, which converts the vertically downward force on the vertical piston into a lateral thrust that can push the two horizontal pistons outward; and converts the vertically upward force on the vertical piston into a lateral pull that can retract the two horizontal pistons inward.

[0033] Furthermore, the lateral pressure or thrust of the two lateral pistons on the inner wall of the turnover box prevents the centering locking device from sliding along the recessed handle, locking the end effector to the center position of the recessed handle of the turnover box.

[0034] Compared with the prior art, the advantages of the present invention are:

[0035] 1. The technical solution adopted in this invention is to configure end effectors at the ends of the two picking arms of the picking device and use a set of centering and locking mechanisms to realize the automatic positioning of the inner curved hook of the end effector in the recessed handle, ensuring the accurate positioning of the center of the recessed handle of the turnover box and being able to stably grab the turnover box so that the automatic stacking system can stably pick up the turnover box and accurately place it in the target position.

[0036] 2. The technical solution adopted in this invention, through the vertical piston and the matching return spring, can conveniently drive the lateral extension and retraction of the two lateral pistons by means of the lifting operation of the end effector, so as to realize the functions of automatic centering, stable clamping, normal movement, and automatic release when in position of the pickup arm end.

[0037] 3. The technical solution adopted in this invention, by configuring end effectors at the ends of the two picking arms of the picking device, realizes the functions of automatic centering, gripping, clamping and moving of a single turnover box or a group of turnover boxes (also known as a turnover box stack). It solves the problems of automatic centering, stable clamping and automatic release at the end of the two picking arms in the usage scenario of gripping, clamping and moving the entire group of turnover boxes, and ensures that the end effector can stably grasp the center of the concave handle of the turnover box during the working process. Attached Figure Description

[0038] Figure 1a This is a schematic diagram of the external structure of the turnover box and the recessed handle;

[0039] Figure 1b This is a cross-sectional view of the turnover box and the recessed handle.

[0040] Figure 2 This is a schematic diagram of a multi-layered stacked turnover box, an end effector, and an end effector control connector;

[0041] Figure 3 This is a schematic diagram illustrating how the tolerance of the control connector affects the deviation of the end effector.

[0042] Figure 4a to Figure 4c This is a structural schematic diagram of the centering and locking device and its components of the present invention;

[0043] Figure 5a and Figure 5b This is a schematic diagram showing the state of the centering and locking device of the present invention after completing centering and locking;

[0044] Figures 6a to 6d This is a schematic diagram of the centering and locking process of the centering and locking device of the present invention;

[0045] Figure 7a and Figure 7b This is a schematic diagram of the centering and locking device of the present invention being released from the recessed handle;

[0046] Figure 8 This is a flowchart of the centering and locking device and end effector of the present invention centering and locking on the recessed handle.

[0047] In the diagram, 0 is the strip platform, 1 is the sloping top edge, 2 is the recessed handle, 2a is the center of the recessed handle, 3 is the sloping top edge, 4 is the longitudinal direction of space, 5 is the outer width of the recessed handle, 6 is the turnover box stack, 7 is the distance from the end effector to its control connector, 8 is the end effector, 8a is the outer center of the end effector, 9 is the control connector, 10 is the deviation caused by the tolerance at the control connector, 11 is the deviation at the end effector, 12 is the centering and locking device, 13 is the upward movement distance of the end effector, 14 is the vertical piston, 15 is the return spring, 16 is the transverse piston, 17 is the connecting bar, 18 is the inner sidewall, 19 is the inner top of the recessed handle, and 20 is the top of the hook. Detailed Implementation

[0048] The invention will now be further described with reference to the accompanying drawings.

[0049] As mentioned earlier, existing automated stacking systems can already smoothly achieve the automatic clamping and movement of individual turnover boxes in the aforementioned stacking process.

[0050] However, existing automated stacking systems cannot guarantee the smooth handling and movement of a stack of multiple crates that have already been stacked together (also known as a crate stack).

[0051] Automated stacking systems require the use of commercially available space guidance systems, which can be customized. However, all of these guidance systems assume that the connection between the pick-and-place mechanism (commonly referred to as the end effector) and the object to be picked up and placed is stable and secure, and aligned with a specific reference point. This is easily achieved when the end effector grips the exterior of a regular object, but it is not easy to achieve with the structure of a tote; because the structure of the tote dictates that it only has two recessed handles for the end effector to grip.

[0052] Therefore, the technical problem to be solved is how to enable the end effector to smoothly enter the recessed handle, tighten its grip, and make the longitudinal centerline of the end effector coincide with the longitudinal centerline of the turnover box. In other words, how to enable the end effector to automatically position itself in the center of the recessed handle and firmly grip the recessed handle.

[0053] The technical solution of the present invention provides a device and method that enables an end effector to automatically position the center of the recessed handle of a turnover box and to firmly grasp the recessed handle of the turnover box, so that an automatic stacking system can firmly pick up the turnover box and place it at the target position. That is, a centering and locking device that can automatically position the center of the recessed handle of the turnover box and to firmly grasp the recessed handle of the turnover box.

[0054] In existing technologies, the picking device for picking up tote boxes in automated stacking systems, such as Figure 2 As shown in the figure, two pickup arms are rotatably mounted on the strip platform 0 of the pickup device. The two pickup arms are symmetrically arranged at both ends of the strip platform. The pickup arms are pin-fixed to the strip platform through control joints, so that the pickup arms can swing within a certain limit relative to the strip platform to realize the functions of inward clamping and outward release.

[0055] At the lower end of each of the two pickup arms, there is an end effector 8 with a hook head, which is used to extend into the recessed handle of the bottom turnover box.

[0056] The end effector is located inside the hook head.

[0057] exist Figure 2 In the process, the height 7 of the end effector 8 to its control connector 9 (i.e., the longitudinal length of the pickup arm) depends on the height of the largest stack of turnover boxes to be processed (i.e., the aforementioned turnover box group), which is the turnover box stack 6 formed by stacking 5 turnover boxes.

[0058] The recessed handle is highly efficient in terms of ergonomics and space, but it presents a challenge for mechanical end effectors because the two end effectors need to be small enough to fit into the recessed handle, align with the center, and be able to move the turnover box securely without slipping.

[0059] For reliable placement and attachment into the recessed handle, a gap of at least 10 mm is required between the side of the end effector and the inner wall of the recessed handle. In other words, the end effector 8 needs to be 20 mm narrower than the outer width 5 of the recessed handle.

[0060] Depend on Figure 2 As shown, the distance 7 from the end effector 8 to its control connector 9 is relatively long, at 594 mm.

[0061] A small change at the control joint will mean a large change at the end effector.

[0062] exist Figure 3In this process, the deviation 10 caused by the tolerance at the control joint will be converted into the deviation 11 at the end effector; for example, the deviation of 0.5mm caused by the tolerance of 0.5mm at the control joint will be converted into the deviation of 5.3mm at the end effector.

[0063] Once the end effector is inside the recessed handle and hooked onto the sloping top edge, it needs to be precisely aligned with the horizontal center of the turntable (or recessed handle). This means there is a potential error of + / - 5.3 mm during the process of the end effector hooking onto the recessed handle, thus confirming a tolerance of + / - 10 mm (20 mm total) between the width of the end effector and the width of the recessed handle.

[0064] Referring to Figures 4a to 5a, in the technical solution of the present invention, the end effector 8 includes a centering and locking device 12 located inside the hook head; the centering and locking device includes a vertical piston fitted with a return spring and two horizontal pistons; wherein, the vertical piston is a T-shaped structure and is movably disposed inside the hook head; its return spring is fitted on the vertical side of the T-shaped structure; the two horizontal pistons are slidably disposed on both sides of the bottom end of the vertical piston; the bottom end of the vertical piston is connected to the tail ends of the two horizontal pistons respectively through two connecting strips.

[0065] Two transverse pistons are symmetrically arranged on both sides of the vertical piston, with the vertical side of the T-shaped structure of the vertical piston as the axis.

[0066] Furthermore, the two transverse pistons are arranged coaxially, with the center line of the vertical side of the T-shaped structure of the vertical piston as the axis of symmetry, and are arranged laterally symmetrically on both sides of the bottom end of the vertical side of the vertical piston.

[0067] The first ends of the two connecting bars are pinned to the bottom end of the vertical piston, forming the first pin joint; the ends of the two connecting bars are pinned to the tail ends of the two horizontal pistons, forming the second pin joint; the longitudinal position (height) of the first pin joint is higher than the longitudinal position (height) of the second pin joint.

[0068] When the top of the vertical piston (the horizontal edge of the T-shaped structure) is pressed downward, the first pin joint descends, pushing the two horizontal pistons outward / extending through the two connecting bars respectively; conversely, when the vertical piston moves upward under the action of the return spring, the first pin joint rises, causing the two horizontal pistons to contract / retract inward.

[0069] In this technical solution, when it is necessary to pick up a turnover box or turnover box group, the picking arm drives the end effector into the recessed handle and moves upward. The top of the vertical piston moves downward under the pressure of the recessed handle, the first pin contact point descends, and the two horizontal pistons are pushed outward / extended by the two connecting bars respectively, so as to realize the automatic centering and automatic clamping function of the end effector.

[0070] When it is necessary to release the turnover box or turnover box assembly, the pickup arm descends, and under the action of the return spring, the vertical piston moves upward, the first pin contact rises, and drives the two horizontal pistons to retract inward, so that the end effector disengages from the recessed handle, realizing the automatic disengagement function of the end effector.

[0071] As shown in Figure 4a to Figure 4c As shown, the centering and locking device 12 of the present invention is a component of the end effector 8. When the end effector enters the recessed handle 2 and moves upward (the upward movement distance of the end effector is marked by 13 in FIG. 4b), the bottom edge of the inclined top edge 1 will contact the top of the vertical piston 14 of the centering and locking device.

[0072] As the end effector continues to move upward into the recessed handle, the vertical piston 14 of the centering locking device will be pressed down by the bottom edge of the inclined top edge (because the overall weight of the turnover box is much greater than the force required to move the vertical piston of the centering locking device downward and compress its return spring 15). The bottom end of the vertical piston of the centering locking device is connected to the two lateral pistons 16 by two connecting bars 17 so as to convert the vertical downward force on the vertical piston into a lateral force that can push the two lateral pistons outward.

[0073] exist Figure 5a and Figure 5b Once both lateral pistons 16 have contacted the two inner walls 18 of the recessed handle, the end effector 8 will stop advancing upwards in the recessed handle because the stroke length of the lateral pistons does not allow the tip of the end effector (i.e. the tip 20 of the hook head) to contact the inner top 19 of the recessed handle.

[0074] refer to Figures 6a to 6d As shown, if one of the two lateral pistons first contacts the inner wall 18 of its corresponding recessed handle of the turnover box, the end effector 8 will continue to move upward so that the other lateral piston can also reach the inner wall of its corresponding recessed handle of the turnover box, thereby ensuring that the outer center 8a of the end effector merges (i.e. coincides) with the center 2a of the recessed handle, which is also the outer center of the entire turnover box. Furthermore, the lateral pressure (pushing force) of the two lateral pistons 16 on the inner wall 18 also sufficiently prevents the centering locking device from sliding along the recessed handle (effectively locking the end effector to the turnover box). The end effector and the turnover box are now securely connected and aligned, allowing the turnover box or stack of turnover boxes (turnkey) to be accurately lifted, moved, and placed in its target position.

[0075] exist Figure 7a and Figure 7bOnce the turnover box is placed in its target position, the end effector 8 will lower relative to the turnover box. At this time, because there is no downward force at the bottom edge of the inclined top edge and the return spring 15 in the centering locking device is released, the vertical piston 14 will be allowed to return to its original position.

[0076] As the vertical piston resets under the action of the return spring, the first pin joint at the lower end of the vertical side of the vertical piston rises. Through the action of the two connecting bars, this causes the two horizontal pistons to retract inwards. Figure 6c Return to the indicated state position. Figure 4c The state position is shown.

[0077] exist Figure 8 The document outlines each step of the centering and locking device locking onto the recessed handle of the turnover box, centering itself, and locking it in place:

[0078] 1) The end effector enters the space below the recessed handle, which is achieved by the end effector being 20mm narrower than the recessed handle.

[0079] 2) The end effector moves upward until the bottom edge of the inclined top edge contacts the top of the vertical piston of the centering and locking device;

[0080] 3) As the end effector continues to advance upward, the vertical piston of the centering and locking device will be pressed down by the bottom edge of the inclined top edge. This downward movement of the vertical piston of the centering and locking device will be converted into a lateral force, pushing the two lateral pistons on both sides of the end effector outward.

[0081] 4) If only one transverse piston contacts its corresponding inner wall (e.g.) Figure 6a As shown in the diagram, the end effector will continue to advance upwards until both lateral pistons contact their inner walls (as shown in the diagram). Figure 6c As shown in the diagram, the center of the end effector will merge with the center of the recessed handle (or turnover box);

[0082] 5) The lateral pressure of the lateral piston on the inner wall locks the end effector to the turnover box, thereby allowing the turnover box to be safely picked up and placed in place;

[0083] 6) Once the crate is in place, the end effector will lower so that it can be removed from the recessed handle (e.g., Figure 7a and Figure 7b As shown in the diagram, during this period, the vertical piston of the centering and locking device returns to its original position.

[0084] The technical solution of this invention includes end effectors configured at the ends of the two picking arms of the picking device, forming a centering and locking mechanism. Through the vertical piston and matching return spring in this mechanism, the lateral extension or retraction of the two lateral pistons can be easily achieved through the lifting and lowering action of the end effectors. This mechanism further realizes functions such as automatic centering, stable clamping, normal movement, and automatic release upon reaching the desired position at the end of the picking arms. The inner hook of the end effector is located within the recessed handle, automatically positioning and locking the center of the recessed handle of the turnover box, ensuring a firm grip on the recessed handle. This enables the automated stacking system to stably pick up the turnover box and accurately place it in the target position. This technical solution effectively solves the problems of automatic centering, stable clamping, and automatic release upon reaching the desired position at the ends of the two picking arms when picking, clamping, and moving the entire set of turnover boxes, ensuring that the end effectors can stably grip the center of the recessed handle of the turnover box during operation, thus smoothly achieving its function.

[0085] This invention is widely applicable to the design and manufacturing of automatic clamping devices for turnover boxes or turnover box groups, as well as automatic stacking system equipment.

Claims

1. A centering and locking mechanism, comprising two picking arms arranged on a pallet or pallets picking device, characterized in that: at the lower end of each picking arm, there is provided a terminal effector with a hook head for extending into the recessed handle of the bottommost pallet; the terminal effector comprises a centering and locking device inside the hook head; the centering and locking device comprises a vertical piston with a return spring and two horizontal pistons; the vertical piston is a T-shaped structure and is arranged inside the hook head in a vertically movable manner; the return spring is sleeved on the vertical edge of the T-shaped structure; the two horizontal pistons are arranged on the two sides of the bottom end of the vertical piston in a horizontally slidable manner; the bottom end of the vertical piston is connected to the tail end of the two horizontal pistons through two connecting strips; the leading end of the two connecting strips is pinned to the bottom end of the vertical piston to form a first pin joint; the trailing end of the two connecting strips is pinned to the tail end of the two horizontal pistons to form a second pin joint; when a pallet or a group of pallets needs to be picked up, the picking arm drives the terminal effector to enter the recessed handle and move upward, the top of the vertical piston is pressed downward by the recessed handle, the first pin joint descends, and the two horizontal pistons are pushed outward through the two connecting strips to extend / extend outward, thereby realizing the automatic centering and automatic clamping functions of the terminal effector; when the pallet or the group of pallets needs to be released, the picking arm descends, and under the action of the return spring, the vertical piston moves upward, the first pin joint rises, and the two horizontal pistons are retracted inward, the terminal effector is released from the recessed handle, and the terminal effector is automatically released in place. the two horizontal pistons are symmetrically arranged on the two sides of the vertical piston with the vertical edge of the T-shaped structure of the vertical piston as the axis. the two horizontal pistons are coaxially arranged with the vertical center line of the vertical edge of the T-shaped structure of the vertical piston as the symmetric axis and are symmetrically arranged on the two sides of the bottom end of the vertical edge of the vertical piston. the longitudinal position of the first pin joint is higher than that of the second pin joint. Once the two horizontal pistons contact the two inner side walls of the recessed handle, the terminal effector will stop advancing upward in the recessed handle. If one of the two horizontal pistons first contacts the inner side wall of the recessed handle of the corresponding pallet, the terminal effector will continue to move upward so that the other horizontal piston can also reach the inner side wall of the recessed handle of the corresponding pallet, thereby ensuring that the outer center of the terminal effector coincides with the center of the recessed handle. the centering and locking mechanism works according to the following steps: 1) the terminal effector enters the space below the recessed handle; 2) the terminal effector moves upward until the bottom edge of the inclined top edge of the recessed handle contacts the top of the vertical piston of the centering and locking device; 3) as the terminal effector continues to advance upward, the vertical piston of the centering and locking device is pressed down by the bottom edge of the inclined top edge, and the downward movement of the vertical piston of the centering and locking device is converted into a horizontal force to push the two horizontal pistons on the two sides of the terminal effector outward. ​ ​ 2. The centering and locking mechanism according to claim 1, characterized in that ​ 3. The centering and locking mechanism according to claim 1, characterized in that ​ 4. The centering and locking mechanism according to claim 1, characterized in that ​ 5. The centering and locking mechanism of claim 1, wherein ​ 6. The centering and locking mechanism according to claim 5, characterized in that ​ 7. The centering and locking mechanism of claim 1, wherein ​ ​ ​ ​ 4) If only one lateral piston contacts its corresponding inner side wall, the end effector will continue to advance upward until both lateral pistons contact their inner side walls, with the longitudinal centerline of the end effector coinciding with the longitudinal centerline of the recessed handle or tote; 5) The lateral pressure or thrust of the lateral pistons against the inner side walls locks the end effector to the tote, allowing the tote to be safely picked and placed into position; 6) Once the tote is placed into position, the end effector is lowered so that it can be removed from the recessed handle, during which time the vertical pistons of the centering and locking mechanism return to their original position.

8. The centering and locking mechanism according to claim 1, characterized in that The centering and locking mechanism, with the lifting or lowering of the end effector, achieves the lateral extension or retraction of the two lateral pistons, thereby achieving the automatic centering, automatic positioning, firm clamping, and automatic release functions of the end of the picking arm, ensuring that the end effector can automatically position the center of the recessed handle of the tote and firmly grasp the recessed handle of the tote.

9. The centering and locking mechanism according to claim 1, characterized in that The bottom end of the vertical piston is connected to the tail end of the two lateral pistons through two connecting strips, converting the vertical downward force on the vertical piston into a lateral thrust that can push the two lateral pistons outward; Converting the vertical upward force on the vertical piston into a lateral pull that can retract the two lateral pistons inward.

10. The centering and locking mechanism according to claim 1, characterized in that The lateral pressure or thrust of the two lateral pistons against the inner side walls of the tote prevents the centering and locking mechanism from sliding along the recessed handle, locking the end effector to the center of the recessed handle of the tote.

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