Material palletizing method of collaborative robots

Abstract

The present invention provides a material palletizing method of a collaborative robot, the collaborative robot includes a mechanical arm and a lifting column, and the method includes: when the palletizing of the previous material layer is completed and the previous material layer does not belong to the highest material layer, the mechanical arm is controlled to move, and it is determined whether it is necessary to control the lifting column to rise, if so, the lifting column is controlled to rise while the mechanical arm moves, so as to palletize the current material layer; when the palletizing of the current material layer is completed, if the current material layer does not belong to the highest material layer, the first step is returned, and if the current material layer belongs to the highest material layer, the mechanical arm and the lifting column are controlled to return to the initial state. Thus, when palletizing each layer, the lifting column is controlled to rise while the mechanical arm moves, so that the mechanical arm and the lifting column can move layer by layer, the action continuity is improved, and the coordinated movement is smoother, so that the palletizing efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of robot palletizing, and in particular to a material palletizing method of a collaborative robot. Background Art

[0002] Taking the material palletizing needs of the packaging industry as an example, after the palletizing work is completed, the height of the stacked body is often more than 1800mm. When performing palletizing tasks, it is difficult for the current collaborative robots to reach the required height by their own functions without the help of external mechanisms. Therefore, in this case, it is usually necessary to add a lifting column on the Z-axis (vertical direction) of the collaborative robot arm so that the arm can move in the vertical direction to meet the requirements of the stacking height in actual production.

[0003] In the related art, the coordinated movement of the lifting column and the robotic arm is stiff and has poor continuity, which affects the palletizing efficiency. Summary of the invention

[0004] In order to solve the problem in the related art that the coordinated movement of the lifting column and the mechanical arm is stiff and has poor continuity, which affects the palletizing efficiency, the present invention proposes the following technical solution.

[0005] The first aspect of the present invention provides a material palletizing method for a collaborative robot, wherein the collaborative robot comprises a robotic arm and a lifting column, wherein the lifting column is installed on the lower surface of the robotic arm base, and the method comprises the following steps: upon completing the palletizing of the previous material layer and the previous material layer does not belong to the highest material layer, controlling the movement of the robotic arm, and determining whether it is necessary to control the lifting column to rise, and if so, controlling the lifting column to rise while the robotic arm moves to palletize the current material layer; upon completing the palletizing of the current material layer, if the current material layer does not belong to the highest material layer, returning to the first step, and if the current material layer belongs to the highest material layer, controlling the robotic arm and the lifting column to return to an initial state.

[0006] In addition, the material stacking method of the collaborative robot according to the above embodiment of the present invention may also have the following additional technical features.

[0007] According to one embodiment of the present invention, determining whether the lifting column needs to rise includes: when the lifting column is at zero position, determining the height of the upper surface of the robot arm base from the ground, and using it as the starting height of the lifting column; when palletizing of the previous material layer is completed, determining a first height of the upper surface of the previous material layer from the ground; and determining whether the lifting column needs to be controlled to rise based on the starting height of the lifting column and the first height.

[0008] According to one embodiment of the present invention, determining the first height of the upper surface of the previous material layer from the ground includes: determining the current stack height and the pallet stack height, wherein the current stack height is the product of the current number of stack layers and the height of a single material, and calculating the first height of the upper surface of the previous material layer from the ground based on the current stack height and the pallet stack height.

[0009] According to one embodiment of the present invention, the first height is calculated by the following formula:

[0010] H1=C 当 ×h 物 +H 盘

[0011] Among them, H1 represents the first height, C 当 Indicates the current number of stack layers, h 物 Indicates the height of a single material, H 盘 Indicates the height of the pallet, 1≤C 当 <C 总 , where C 总 Indicates the number of complete stack layers, C 当 , C 总 All are integers.

[0012] According to an embodiment of the present invention, determining whether it is necessary to control the lifting column to rise according to the starting height of the lifting column and the first height includes: when the first height is less than or equal to the starting height of the lifting column, determining that it is not necessary to control the lifting column to rise; when the first height is greater than the starting height of the lifting column, determining that it is necessary to control the lifting column to rise.

[0013] According to one embodiment of the present invention, controlling the lifting column to rise while the robotic arm moves includes: while the robotic arm moves, determining a second height to which the lifting column currently needs to rise based on a starting height of the lifting column and the first height, and controlling the lifting column to rise to the second height.

[0014] According to an embodiment of the present invention, determining a second height to which the lifting column currently needs to rise based on the starting height of the lifting column and the first height includes: acquiring a maximum stroke height of the lifting column; calculating a difference between the first height and the starting height of the lifting column; if the difference is less than the maximum stroke height, using the difference as the second height to which the lifting column currently needs to rise; if the difference is greater than or equal to the maximum stroke height, using the maximum stroke height as the second height to which the lifting column currently needs to rise.

[0015] According to an embodiment of the present invention, before controlling the lifting column to rise to the second height, the method further includes: optimizing the second height based on the starting height of the lifting column and the first height.

[0016] According to one embodiment of the present invention, the second height is optimized based on the starting height of the lifting column and the first height, including: determining the distance between the flange center and the base when the reachable range of the robot arm in the horizontal plane is the largest, and using it as the maximum reachable height of the robot arm; determining the height of the leading point of the robot arm during palletizing; calculating the optimal height of the lifting column according to the height of the leading point, the maximum reachable height, the starting height of the lifting column and the first height; and optimizing the second height based on the optimal height of the lifting column.

[0017] According to one embodiment of the present invention, the optimal height of the lifting column is calculated by the following formula:

[0018]

[0019] Among them, H 优 Indicates the optimal height of the lifting column, H1 indicates the first height, H 前 Indicates the front height, h 物 Indicates the height of a single material, H 前 With h 物 The sum of the values ​​represents the height of the preceding point, H max2 Indicates the maximum reachable height of the robot arm, H 起 Indicates the starting height of the lifting column.

[0020] According to one embodiment of the present invention, optimizing the second height based on the optimal height of the lifting column includes: obtaining the maximum stroke height of the lifting column; optimizing the second height according to the optimal height of the lifting column and the maximum stroke height, wherein if the optimal height of the lifting column is less than the maximum stroke height, the second height is equal to the optimal height of the lifting column; if the optimal height of the lifting column is greater than or equal to the maximum stroke height, the second height is equal to the maximum stroke height.

[0021] According to one embodiment of the present invention, during the process of palletizing the current material layer, it is determined whether the inverse solution of the stacking points of the current material fails; if the inverse solution of the stacking points of the current material fails, the stacking method of the current material layer is re-determined to obtain a determined stacking method; and the movement of the robot arm is controlled according to the determined stacking method to palletize the current material layer.

[0022] According to one embodiment of the present invention, the stacking method of the current material layer includes the stacking points of the current material and the stacking order of the current material layer, the stacking points of the current material include an entry point, a front point and a discharge point, and re-determining the stacking method of the current material layer includes: determining the stacking order of the current material layer, determining the discharge point of the current material according to the determined stacking order, wherein the determined stacking order is from far to near in the perspective of the collaborative robot; and determining the front point and the entry point of the current material in sequence based on the determined discharge point.

[0023] According to one embodiment of the present invention, the leading point and the entry point of the current material are determined in sequence based on the determined discharge point, including: determining a preset height between the leading point and the upper surface of the previous material layer, and a preset distance between the leading point and the determined discharge point, wherein the preset height is less than the height of a single material; determining the leading point of the current material based on the preset height and the preset distance; determining the entry point of the current material based on the leading point, wherein the determined entry point and the determined leading point are located in the same horizontal plane, and the horizontal plane projection of the determined entry point does not overlap with the horizontal plane projection of the current stack type.

[0024] According to one embodiment of the present invention, the movement of the robot arm is controlled according to the determined stacking method to palletize the current material layer, including: palletizing each material of the current material layer according to the determined stacking order, wherein, for each of the materials, the robot arm is controlled to move axially to a determined entry point, linearly to a determined front point, and linearly to a determined discharge point in sequence to palletize the material.

[0025] The technical solution of the embodiment of the present invention is to control the movement of the robot arm and determine whether it is necessary to control the lifting column to rise when the palletizing of the previous material layer is completed and the previous material layer does not belong to the highest material layer. If so, the lifting column is controlled to rise while the robot arm moves to palletize the current material layer. When the palletizing of the current material layer is completed, if the current material layer does not belong to the highest material layer, it returns to the first step. If the current material layer belongs to the highest material layer, the robot arm and the lifting column are controlled to return to the initial state.

[0026] Therefore, when palletizing each layer, the lifting column is controlled to rise and the robot arm moves at the same time, realizing the coordinated movement of the robot arm and the lifting column layer by layer, improving the continuity of the movement, making the coordinated movement smoother, and thus improving the palletizing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Flow chart of a material palletizing method of a collaborative robot according to an embodiment of the present invention.

[0028] Figure 2The flowchart of determining whether it is necessary to control the lifting column to rise is shown in one embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of the movement trajectory of the robot arm after stacking a layer of materials according to an embodiment of the present invention.

[0030] Figure 4 A schematic diagram of the optimal height of a lifting column according to an example of the present invention.

[0031] Figure 5 It is a schematic diagram of forward-sequence palletizing according to a specific example of the present invention.

[0032] Figure 6 This is a schematic diagram of a specific example of the present invention, which is palletizing in forward order and then in reverse order. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that the current movements of collaborative robots are divided into blocking movements and non-blocking movements. Blocking movements mean that the entire program cannot do anything else before reaching a specified point. Non-blocking movements mean that some other logical processing and communication control can be performed before reaching a specified point. The embodiment of the present invention controls the addition of non-blocking movements, and controls the lifting column during the movement of the collaborative robot's mechanical arm, so as to control the lifting column and the mechanical arm to move simultaneously under certain conditions, thereby realizing the coordinated work of the mechanical arm and the lifting column.

[0035] Figure 1 Flow chart of a material palletizing method of a collaborative robot according to an embodiment of the present invention.

[0036] The collaborative robot includes a robotic arm and a lifting column, wherein the lifting column is installed on the lower surface of the robotic arm base along the Z-axis direction (vertical direction) of the robotic arm.

[0037] like Figure 1 As shown, the material stacking method of the collaborative robot includes the following steps S1 and S2.

[0038] S1, when the palletizing of the previous material layer is completed and the previous material layer does not belong to the highest material layer, the robot arm is controlled to move, and it is determined whether it is necessary to control the lifting column to rise. If so, the lifting column is controlled to rise while the robot arm moves to palletize the current material layer.

[0039] It should be noted that the collaborative robot is located in the middle of the pallet pallets on the left and right sides, and realizes palletizing on the left and right sides in turn. There is a material conveyor belt directly in front of the robot, and the robot transports the material from the conveyor belt to the pallet pallet (for stacking materials). When the robot arm performs the palletizing process, there is an initial posture, which is used to maintain a safe state before each start or after stopping. Generally, in this state, it is necessary to ensure that the center of the flange or the tool connected at the end is facing the incoming direction of the assembly line conveyor belt to facilitate quick response and startup. The materials on the conveyor belt are stacked on the pallet pallets on the left and right sides of the collaborative robot through the end suction cup tool.

[0040] The material layer includes at least one material box (which can be a cube), and the sizes of the material boxes can be the same or different. Palletizing refers to stacking the material boxes layer by layer on the pallet pallets on the left and right sides of the robot arm. When the highest material layer (the last layer of material) on one side is completed, it means that the stacking of the side is completed. The stacking type refers to the stack of materials that have been stacked. For example, 10 layers of materials are stacked on the pallet pallet to form a stacking type.

[0041] Specifically, before palletizing begins, the number of palletizing layers and the number of materials in each material layer need to be set. After each material layer is palletized, that is, after the last material of the material layer is stacked and the material layer does not belong to the highest material layer, the robot arm is controlled to move, and it is determined whether the lifting column needs to be controlled to rise. If so, the lifting column is controlled to rise while the robot arm moves to meet the height conditions for palletizing the current material layer, thereby achieving the stacking of the current material layer.

[0042] S2. When the palletizing of the current material layer is completed, if the current material layer does not belong to the highest material layer, return to the first step; if the current material layer belongs to the highest material layer, control the robot arm and the lifting column to return to the initial state.

[0043] Specifically, when the palletizing of the current material layer is completed, it is determined whether the material layer is the highest material layer. If so, the robot arm and the lifting column are controlled to restore the robot arm and the lifting column to their initial state; if not, return to the first step, i.e., step S1, that is, control the movement of the robot arm, and determine whether it is necessary to control the lifting column to rise. If so, the lifting column is controlled to rise while the robot arm moves to palletize the next material layer.

[0044] The initial state of the robot arm refers to the initial position, and the initial state of the lifting column refers to the zero position (the lifting height of the lifting column is 0).

[0045] That is, step S1 is executed cyclically until the last material layer or the highest material layer is stacked, then the loop is exited and the robot arm and the lifting column are controlled to return to the initial state.

[0046] In general, the embodiment of the present invention realizes a complete palletizing process by cooperatively controlling the robot arm and the lifting column: first, the robot arm is controlled to move to palletize the first material layer. Generally speaking, when palletizing the first material layer, the lifting column does not need to rise. When the palletizing of the first material layer is completed, the robot arm is controlled to move, and at the same time, it is determined whether the lifting column needs to be controlled to rise. If so, the lifting column is controlled to rise at the same time to complete the palletizing of the second material layer. After completion, the robot arm is controlled to move, and at the same time, it is determined whether the lifting column needs to be controlled to rise. If so, the lifting column is controlled to rise at the same time to complete the palletizing of the third material layer. This cycle is repeated until the palletizing of the last layer of materials is completed, and the robot arm and the lifting column are controlled to move to the initial state.

[0047] In the related art, the lifting column is controlled only at its minimum travel height and maximum travel height, and the robot arm is not allowed to move when the lifting column is moving, that is, a blocking movement strategy is adopted. This increases redundant waypoint movement actions, reduces the overall beat of the robot, and thus affects the palletizing efficiency.

[0048] Compared with the related art, the embodiment of the present invention controls the movement of the robot arm and determines whether the lifting column needs to rise when each material layer (not the last layer) is stacked. If necessary, the lifting column is controlled to rise while the robot arm is kept moving. In this way, not only the layer-by-layer control of the lifting column is achieved, but also a non-blocking motion strategy is adopted to determine and control the lifting column to rise while the robot arm moves, which reduces redundant movement actions at each layer, optimizes the coordinated movement between the collaborative robot robot arm and the lifting column, and can improve the movement continuity between the robot arm and the lifting column, thereby improving the stacking efficiency.

[0049] Therefore, the material stacking method of the collaborative robot in the embodiment of the present invention controls the lifting column to rise and the robotic arm to move at the same time when stacking each layer, thereby realizing the layer-by-layer coordinated movement of the robotic arm and the lifting column, improving the continuity of the movement, making the coordinated movement smoother, and thus improving the stacking efficiency.

[0050] In one embodiment of the present invention, Figure 2 As shown, the determination in step S1 of whether the lifting column needs to be raised may include the following steps S11 to S13:

[0051] S11. When the lifting column is at zero position, determine the height of the upper surface of the robot arm base from the ground, and use it as the starting height of the lifting column.

[0052] Zero position refers to the position of the lifting column in its initial state without any lifting action, that is, the rising height is zero when the lifting column is in zero position.

[0053] Specifically, after the lifting column is installed to the lower surface of the robot arm base along the Z-axis direction of the robot arm, before palletizing begins, the robot arm and the lifting column are in the initial state. In the initial state, the lifting column is in the zero position. At this time, the lifting height of the lifting column is 0. Determine the height of the upper surface of the robot arm base from the ground, and determine this height as the starting height H of the lifting column. 起 , used to control the lifting column during subsequent palletizing.

[0054] S12. When the palletizing of the previous material layer is completed, determine a first height of the upper surface of the previous material layer from the ground.

[0055] The first height refers to the distance between the upper surface of a material layer that has just been stacked (not the highest material layer) and the ground, that is, the sum of the current stack height and the pallet height.

[0056] Specifically, each time a material layer is stacked and the material layer does not belong to the highest layer, a first height of the upper surface of the material layer from the ground is determined to meet the stacking height of the next material layer.

[0057] In one example, determining the first height of the upper surface of the previous material layer from the ground in step S12 may include: determining the current stack height and the pallet stack height, wherein the current stack height is the product of the current number of stack layers and the height of a single material, and calculating the first height of the upper surface of the previous material layer from the ground based on the current stack height and the pallet stack height.

[0058] Specifically, assuming that the heights of the stacked materials are the same, after stacking a material layer, determine the current number of stacking layers (i.e. the number of currently stacked material layers) and the height of a single material. The product of the two is the current stacking height, and the height of the pallet stack is determined. The sum of the current stacking height and the pallet stack is the first height of the upper surface of the material layer from the ground.

[0059] That is, the first height is calculated by the following formula:

[0060] H1=C 当 ×h 物 +H 盘

[0061] Among them, H1 represents the first height, C 当 Indicates the current number of stack layers, h 物 Indicates the height of a single material, H 盘 Indicates the height of the pallet, 1≤C 当 <C 总 , where C 总 Indicates the number of complete stacking layers (total number of material layers) that need to be stacked, C 当 , C 总 All are integers.

[0062] S13: determining whether it is necessary to control the lifting column to rise according to the starting height of the lifting column and the first height.

[0063] In an example, step S13 may include: when the first height is less than or equal to the starting height of the lifting column, determining that the lifting column does not need to be controlled to rise; when the first height is greater than the starting height of the lifting column, determining that the lifting column needs to be controlled to rise.

[0064] Specifically, when the first height is less than or equal to the starting height of the lifting column, it means that the current height of the collaborative robot meets the height required for the next layer of palletizing, and it is determined that the lifting column does not need to rise, that is, the lifting column is still in the zero position, and its rising height is 0; when the first height is greater than the starting height of the lifting column, it means that the current height of the collaborative robot does not meet the height required for the next layer of palletizing, and it is determined that the lifting column needs to rise or be raised. Generally speaking, the second height that needs to be risen can be the difference between the first height and the starting height of the lifting column.

[0065] In one embodiment of the present invention, controlling the lifting column to rise while the robot arm moves in step S1 may include: while the robot arm moves, determining a second height to which the lifting column currently needs to rise based on a starting height and a first height of the lifting column, and controlling the lifting column to rise to the second height.

[0066] The second height refers to the height to which the lifting column needs to rise or lift after a certain material layer is stacked.

[0067] Specifically, when the lifting column needs to rise, the lifting column is controlled to rise while controlling the movement of the robotic arm. The second rising height is determined based on the starting height and the first height of the lifting column to achieve coordinated action of the robotic arm and the lifting column to complete the palletizing of the current material layer.

[0068] Further, determining the second height to which the lifting column currently needs to rise based on the starting height of the lifting column and the first height may include: acquiring the maximum stroke height of the lifting column; calculating the difference between the first height and the starting height of the lifting column; if the difference is less than the maximum stroke height, using the difference as the second height to which the lifting column currently needs to rise; if the difference is greater than or equal to the maximum stroke height, using the maximum stroke height as the second height to which the lifting column currently needs to rise.

[0069] The maximum travel height refers to the maximum height to which the lifting column can rise, which is determined according to the factory parameters of the lifting column or the properties of the lifting column itself.

[0070] Specifically, the second height to which the lifting column needs to rise is the difference between the first height and the lifting column, provided that the difference is less than the maximum stroke height. If the difference is greater than or equal to the maximum stroke height, the maximum stroke height is determined as the second height.

[0071] That is to say, when you need to stack any layer of materials, calculate the second height that the lifting column needs to rise by the following formula:

[0072]

[0073] Among them, H2 represents the second height, H1 represents the first height, and H 起 Indicates the starting height of the lifting column, H max1 Indicates the maximum travel height of the lifting column.

[0074] In the related art, the lifting column only rises at the minimum travel point and the maximum travel point, which increases redundant waypoint movement and reduces the overall beat. However, when each layer (not the last layer, which does not require the lifting column to rise) is stacked, the embodiment of the present invention immediately controls the movement of the robot arm and calculates the second height (greater than or equal to 0) that the lifting column needs to rise. The lifting column is controlled to rise according to the height, and the robot arm is allowed to continue to move. The strategy of lifting the column rising layer by layer is implemented, and the rising amplitude of each layer is small. When performing the stacking operation of the corresponding layer, the robot arm body reduces redundant movement.

[0075] When performing palletizing operations, when palletizing on the corresponding side for the first time, a blocking movement strategy is implemented, that is, the lifting column is first moved to the specified height, and then the robotic arm is moved. When palletizing on the corresponding side is not performed for the first time, the non-blocking movement strategy of the embodiment of the present invention is adopted, so that the robotic arm moves while the lifting column moves. For palletizing, after the last material box of the current layer (not the last layer) is stacked, that is, the lifting column is controlled to rise to a certain height (when the lifting column needs to rise), the space above the stack is empty, so there is no need to consider the problem of interference and collision when the lifting column rises. Therefore, the lifting column rise start time point can be set to the time point when the last material box of the current layer is stacked. Once this time point passes, the non-blocking strategy can be immediately adopted. During the process of the robotic arm moving to the subsequent target point, the lifting column is also rising.

[0076] In general, the embodiment of the present invention determines the starting height of the lifting column in advance, and on this basis realizes the coordinated work of the robot arm and the lifting column to realize a palletizing process: first, the robot arm is controlled to move to palletize the first material layer. Generally speaking, when palletizing the first material layer, the lifting column is usually not required to move. When the first material layer is palletized, the first height of the upper surface of the first material layer from the ground is determined, the robot arm is controlled to move, and the lifting column is controlled to rise to a certain height based on the first height and the starting height of the lifting column to complete the palletizing of the second material layer. After that, the first height of the upper surface of the second material layer from the ground is determined, the robot arm is controlled to move, and the lifting column is controlled to rise to a certain height based on the first height and the starting height of the lifting column to complete the palletizing of the third material layer. This cycle is repeated until the palletizing of the last layer of materials is completed, and the robot arm and the lifting column are controlled to move to the initial state.

[0077] like Figure 3 As shown, assuming that the end of the robotic arm is located at point A when the last material box of the current layer of the left stack of the robotic arm is stacked, the robotic arm needs to move so that its end reaches point B. If the robotic arm moves from point A to point B (directly above the conveyor belt) in T1 seconds, the lifting column's rising movement will take T2 seconds, and the lifting column will arrive before the robotic arm. If a blocking motion method is used, the total time is T1+T2 seconds, and if the layer-by-layer rising strategy of the embodiment of the present invention is used, the total time is T1 second. It can be seen that each time it rises, the lifting column can be faster by T2 seconds, and quantitative changes lead to qualitative changes. The above-mentioned collaborative strategy of the embodiment of the present invention helps to improve production efficiency.

[0078] As a result, during the palletizing process, the robot arm and the lifting column work together to rise layer by layer, with each layer rising a small amount. When the lifting column rises, the robot arm keeps moving, which greatly reduces redundant movement and improves palletizing efficiency.

[0079] It should be noted that in the palletizing process, there are two main points (positions) that have a greater impact on the stacking of a material: the leading point and the discharge point. The role of the leading point is to avoid interference and collision that may be caused by the straight up and down movement between materials. Therefore, the leading point is usually twice the height of the material than the discharge point, and has a leading distance and leading direction to ensure that the material can enter the discharge point from the upper side and stack the material into the stacked material. For the layer-by-layer rising strategy of the lifting column, in order to prevent the inappropriate movement of the lifting column height (for example, when it is necessary to be compatible with materials of different sizes, the lifting column may be improperly calculated), which may easily lead to the failure of the robot arm to inverse the leading point or close to the failure of the inverse solution, the layer-by-layer rising strategy of the lifting column needs to be further optimized.

[0080] That is, in one embodiment of the present invention, before controlling the lifting column to rise to the second height, the method may further include: optimizing the second height based on the starting height of the lifting column and the first height.

[0081] Furthermore, optimizing the second height based on the starting height of the lifting column and the first height may include: determining the distance between the flange center and the base when the reachable range of the robot arm in the horizontal plane is the largest, and using it as the maximum reachable height of the robot arm; determining the height of the leading point when the robot arm is stacking; calculating the optimal height of the lifting column based on the height of the leading point, the maximum reachable height, the starting height of the lifting column and the first height; and optimizing the second height based on the optimal height of the lifting column.

[0082] Still further, optimizing the second height based on the optimal height of the lifting column may include: obtaining the maximum stroke height of the lifting column; optimizing the second height according to the optimal height of the lifting column and the maximum stroke height, wherein if the optimal height of the lifting column is less than the maximum stroke height, the second height is equal to the optimal height of the lifting column; if the optimal height of the lifting column is greater than or equal to the maximum stroke height, the second height is equal to the maximum stroke height.

[0083] Specifically, by controlling the movement of the robot arm through the teach pendant, we can obtain that when the robot arm has the largest reachable range in the horizontal plane, that is, the XOY plane of the robot base coordinate system (generally, when the third joint is farther away from 0°, the reachable range is larger), the flange center of the robot arm is higher than the base, and the distance between the two is taken as the maximum reachable height of the robot arm (this method can be applied to robot arms of different brands and models). Determine the height of the leading point required for the robot arm to stack a material.

[0084] Generally speaking, when the third joint of the robot arm is further away from 0°, the reachable range of the robot arm in the XOY plane is the largest. At this time, the distance between the flange center of the robot arm and the base is, for example, 70 mm. 70 mm can be used as the maximum reachable height of the robot arm.

[0085] It should be noted that if Figure 4 As shown in the figure, when the height of the lifting column or the base of the robot arm is lower than the middle position P between the front point and the discharge point in the Z direction, the maximum reachable height H of the robot arm max2 When the robot arm is equipped with a lifting column, the capsule-shaped reachable space, that is, the reachable space of the robot arm when the arm is extended, can make both the front point and the discharge point reachable in a balanced manner, and the inverse solution is successful.

[0086] The optimal height of the lifting column is calculated by the following formula:

[0087]

[0088] Among them, H 优 Indicates the optimal height of the lifting column, H1 indicates the first height, H前 Indicates the front height (the height from the lower surface of the front point to the upper surface of the discharge point), h 物 Indicates the height of a single material, H 前 With h 物 The sum of the values ​​represents the height of the front point (the height of the upper surface of the front point from the upper surface of the discharge point), H max2 Indicates the maximum reachable height of the robot arm, H 起 Indicates the starting height of the lifting column.

[0089] It is understandable that when palletizing any material, there are corresponding entry points, leading points and discharge points. The shape and size of each point are the same as the shape and size of the material. The position of each point can be set by the user, as long as the conditions of non-collision and non-interference are met (see the part of forward stacking described later). In the above formula, the starting height of the leading point is one times the material height, and the leading height is a parameter provided by the user. In practical applications, the leading height is generally the floating range of the height processing error of a single material, which is generally ±5mm, so the leading height is 10mm. For example, when the material height is about 300mm, the height of the leading point is about 310mm.

[0090] Finally, the second height is recalculated by the following formula to optimize the second height:

[0091]

[0092] Among them, H2 represents the second height, H 优 Indicates the optimal height of the lifting column, H max1 Indicates the maximum travel height of the lifting column.

[0093] In the related art, facing a wide variety of material sizes, the height planning effect of the lifting column is not ideal, resulting in failure of inverse solution of some points that the robot arm needs to move to. However, the embodiment of the present invention can prevent the failure or near failure of inverse solution when being compatible with materials of different sizes by optimizing the second height, ensuring that the robot arm can successfully inversely solve each point that needs to be moved, and reducing action redundancy.

[0094] It should be noted that the layer-by-layer collaborative motion strategy and optimization method between the robot arm and the lifting column in the embodiment of the present invention are not only applicable to the scenario where the lifting column needs to rise during the stacking process, that is, rising layer by layer, but also to the scenario where the lifting column needs to descend during the unloading process, that is, descending layer by layer.

[0095] Therefore, by optimizing or updating the second height to which the lifting column needs to rise, it is possible to solve the problem of inverse solution failure or near failure due to inappropriate height calculation due to various reasons, thereby ensuring the successful implementation of palletizing while improving the palletizing efficiency.

[0096] It should be noted that if Figure 5 As shown (palletizing process on the right), Figure 5 1, 2, 3, 4, etc. in the figure represent the material number. When the robot arm performs palletizing, the palletizing process of the robot arm is usually to move the axis (joint movement moveJ) to the entry point, then move the axis to the front point, and then move the axis to the discharge point, and refer to Figure 5 The stacking order of each layer of materials is from near to far (far and near is for the robot, that is, from the perspective of the robot). This is a common method of palletizing technology, and the embodiment of the present invention refers to this stacking method as positive sequence palletizing. When the number of layers of the stacking type that needs to be stacked is particularly high, it is easy for the lifting column to reach its maximum stroke height, but the flange center of the robot arm still needs to continue to be raised in the Z direction. At this time, at least one material layer (such as the last one or two layers) may fail to be inverted. For this reason, the embodiment of the present invention improves the positive sequence palletizing method to meet the requirements of high-layer stacking types.

[0097] That is, in one embodiment of the present invention, the material stacking method of the collaborative robot may also include: in the process of stacking the current material layer, determining whether the inverse solution of the stacking point of the current material fails; if the inverse solution of the stacking point of the current material fails, redetermining the stacking method of the current material layer to obtain a determined stacking method; and controlling the movement of the robotic arm according to the determined stacking method to stack the current material layer.

[0098] The stacking method of the current material layer includes the stacking points of the current material and the stacking order of the current material layer. The stacking points of the current material include the entry point (also called the preparation point), the front point and the discharge point.

[0099] Among them, the inverse solution refers to solving the joint position according to the end position of the robot arm (specifically the entry point, the leading point and the discharge point in the embodiment of the present invention). Only when the entry point, the leading point and the discharge point are successfully inversely solved can effective and safe palletizing be carried out.

[0100] Specifically, when palletizing each material layer, it is preferably performed in forward sequence. Each material corresponds to a set of palletizing points, including an entry point, a front point and a discharge point. It can be determined according to any existing feasible method whether the inverse solution of at least one of the entry point, the front point and the discharge point has failed. If so, it means that the palletizing sequence and the palletizing points (entry point, front point and / or discharge point) of the current material layer are re-determined to obtain the determined palletizing sequence and the palletizing points, and then the determined palletizing points are reversed to ensure the success of the reverse solution. The movement of the robot arm is controlled according to the inverse solution result and the determined palletizing sequence to ensure the successful palletizing of the current material layer.

[0101] In one example, redetermining the stacking method of the current material layer may include: determining the stacking order of the current material layer, determining the discharge point of the current material according to the determined stacking order; and determining the front point and the entry point of the current material in sequence based on the determined discharge point.

[0102] The determined stacking order is from far to near (from the perspective of the robot), that is, for each material layer, the material is first stacked to the discharge point farthest from the robot, and finally the material is stacked to the discharge point closest to the robot.

[0103] Furthermore, determining the leading point and the entry point of the current material in sequence based on the determined discharge point may include: determining a preset height between the leading point and the upper surface of the previous material layer, and a preset distance between the leading point and the determined discharge point, wherein the preset height is less than the height of a single material; determining the leading point of the current material based on the preset height and the preset distance; determining the entry point of the current material based on the leading point, wherein the determined entry point and the determined leading point are located in the same horizontal plane, and the horizontal plane projection of the determined entry point does not overlap with the horizontal plane projection of the current stack type.

[0104] The preset height is to ensure that the front point only increases the lifting height a little to prevent collision with the previous material layer, which can be less than the height of a single material (the current material), and the preset distance is to ensure that the robot arm can safely transport the material to the discharge point of the current material without collision. The preset height and preset distance can be determined according to the actual specific situation, as long as the purpose of safe stacking of materials can be achieved (no interference and collision with the stacked materials).

[0105] Specifically, first, according to the stacking order determined by the current material layer, the discharge point of each material in the layer can be obtained, and the determined discharge point of each material can be obtained. Then, for each material, determine the preset height between its leading point and the upper surface of the previous material layer, and the preset distance between its leading point and the determined discharge point, and then combine the stacking order from far to near to obtain the determined leading point position (the height is lowered compared to the original leading point). Finally, for each material, the entry point of the material is determined on the basis of the determined leading point. The entry point is at the same horizontal point as the determined leading point (the height is lowered compared to the original entry point), and the horizontal plane projection of the entry point does not overlap with the horizontal plane projection of the current stack type to ensure the safe movement of the robot arm. For the right-side palletizing process, the entry point, leading point and discharge point are determined as follows: Figure 6 The 16th material shown (palletizing process on the right) Figure 6 The 1, 2, 3, 4, etc. in the table represent the material numbers.

[0106] In one example, controlling the movement of a robotic arm according to a determined palletizing method to palletize a current material layer may include: palletizing each material in the current material layer according to a determined palletizing sequence, wherein, for each material, controlling the robotic arm to sequentially move axially to a determined entry point, move linearly to a determined front point, and move linearly to a determined discharge point to palletize the material.

[0107] Among them, the determined stacking order is from far to near (from the perspective of the robot arm, that is, the robot arm is used as the reference).

[0108] Specifically, the materials in the current material layer are stacked in sequence according to the stacking order from far to near, wherein for each material, the movement of the robot arm is controlled according to its determined entry point, front point and discharge point, that is, the determined entry point, front point and discharge point are inversely solved respectively to ensure the success of the inverse solution, and then the movement of the robot arm is controlled according to the inverse solution result to realize the stacking of the material, thereby completing the stacking of the current material layer.

[0109] Reference Figure 6 For material 16 in the reverse stacking process, the visual effect is that the end of the robot arm carries the material, almost sticks to the upper surface of the stacked material box, and moves horizontally into the stack for stacking. While ensuring the success of the reverse solution, the overall height of the final stack is increased, and the performance of the lifting column after installation is fully utilized. At the same time, in order to avoid the risk of collision, the numbering order (stacking order) of the stacked materials is opposite to the forward order, and the leading direction is also opposite. This new planning strategy is called reverse stacking in the embodiment of the present invention.

[0110] It should be noted that in the embodiment of the present invention, palletizing is performed preferentially in a forward order palletizing manner, and a judgment is simultaneously made as to whether the inverse solution fails. When the inverse solution fails, the reverse order palletizing strategy of the embodiment of the present invention is adopted, that is, the palletizing method of the current material layer is re-determined, and the movement of the robot arm is controlled according to the determined palletizing method to palletize the current material layer. That is: in the motion planning of the pallet type, the forward order is the main one, and the reverse order is the auxiliary one. The condition for enabling the reverse order can be judged according to whether there is a situation in which the inverse solution fails at the material-related points of the current layer (existing technology). If a waypoint fails to be inversely solved, the current layer needs to abandon the forward order palletizing and use reverse order palletizing instead. If there is no waypoint inverse solution failure, the current layer uses the forward order planning.

[0111] For example, when performing the right-side palletizing process (the robot arm places the material on the right pallet), Figure 5 As shown, the 1st to 5th layers are stacked in forward order. At this time, the maximum number of layers can only be stacked is 5 (that is, the lifting column reaches the maximum travel height), and the target number of layers is 6 or 7. At this time, the inverse solution of the 6th and 7th layer entry points and / or front points will fail, so the reverse order stacking strategy of the embodiment of the present invention is adopted. Figure 6, taking the 6th layer as an example, the 1st to 5th layers are stacked in positive order, and the 6th layer is stacked in reverse order. It can be seen that the planned paths are different. Figure 5 and Figure 6 The 16th material is placed in a different position ( Figure 5 The middle distance is closest to the robot arm. Figure 6 The middle distance robot arm is the farthest), compared with the forward sequence palletizing, the height of the palletizing point is lowered, so the height to which the lifting column needs to rise will also be lowered. At this time, it can be ensured that the entry point and the front point of the 6th layer can be reached, and the inverse solution is successful, ensuring the successful stacking of the 6th layer of materials.

[0112] Therefore, by improving the forward stacking strategy in the related technology, a reverse stacking strategy is obtained. Even when the lifting column has reached the highest travel height, the relevant layer points can be successfully reversed to increase the overall stack height, while avoiding collision risks and ensuring successful stacking.

[0113] It should be noted that when the failure of the inverse solution is caused by the lifting column having reached the maximum stroke height and still needs to rise, since the lifting column has reached the maximum stroke height, there is no need to adopt the above-mentioned strategy for optimizing the rising height of the lifting column (i.e., the second height). Instead, a reverse stacking strategy is used. Compared with the forward stacking strategy, the height of the entry point and the front point from the ground is reduced, thereby ensuring the success of the inverse solution of the entry point and the front point.

[0114] In summary, in the process of palletizing, the embodiment of the present invention performs layer-by-layer and adaptive planning for the height that the lifting column needs to rise, so as to reduce redundant actions, improve the continuity of the action between the lifting column and the robot arm, and optimize the rising height to avoid the failure of reverse solution when there are many materials of different sizes; when the reverse solution fails at high levels, a reverse stacking strategy is adopted to maximize the use of the lifting column, ensure that the robot arm can fully move in the vertical direction, improve the stacking efficiency, and help the stacking process to further increase the height of the stack. Therefore, the embodiment of the present invention is universal and highly feasible, and can maximize the use and give full play to the improvement of the overall performance by installing lifting columns, greatly improve the stacking efficiency, and ensure the safety of stacking.

[0115] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0116] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0117] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0118] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0119] A person of ordinary skill in the art can understand that all or part of the steps carried by the method of the above-mentioned embodiment can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, and the program, when executed, includes one or a combination of the steps of the method embodiment. In addition, each functional unit in each embodiment of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into one module. The above-mentioned integrated module can be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0120] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A material palletizing method of a collaborative robot, It is characterized in that The collaborative robot comprises a mechanical arm and a lifting column, wherein the lifting column is mounted on the lower surface of the mechanical arm base, and the method comprises the following steps: When the palletizing of the previous material layer is completed and the previous material layer does not belong to the highest material layer, the robot arm is controlled to move, and it is determined whether it is necessary to control the lifting column to rise, and if so, the lifting column is controlled to rise while the robot arm moves, so as to palletize the current material layer; When the palletizing of the current material layer is completed, if the current material layer does not belong to the highest material layer, the process returns to the first step; if the current material layer belongs to the highest material layer, the robot arm and the lifting column are controlled to return to the initial state. Determining whether the lifting column needs to be raised includes: When the lifting column is at zero position, determining the height of the upper surface of the robot arm base from the ground, and using it as the starting height of the lifting column; When the palletizing of the upper material layer is completed, determining a first height of the upper surface of the upper material layer from the ground; Determining whether it is necessary to control the lifting column to rise according to the starting height of the lifting column and the first height, Controlling the lifting column to rise while the mechanical arm moves includes: While the robot arm is moving, a second height to which the lifting column currently needs to rise is determined based on the starting height of the lifting column and the first height, and the lifting column is controlled to rise to the second height. Before controlling the lifting column to rise to the second height, the method further includes: optimizing the second height based on the starting height of the lifting column and the first height, Optimizing the second height based on the starting height of the lifting column and the first height includes: Determine the distance between the center of the flange and the base when the reachable range of the robotic arm in the horizontal plane is the largest, and use it as the maximum reachable height of the robotic arm; Determine the height of the leading point of the robot arm during palletizing; Calculating the optimal height of the lifting column according to the height of the leading point, the maximum achievable height, the starting height of the lifting column and the first height; The second height is optimized based on the optimal height of the lifting column.

2. The material palletizing method of the collaborative robot according to claim 1, It is characterized in that Determining a first height of the upper surface of the previous material layer from the ground comprises: Determine the current stack height and the pallet height, wherein the current stack height is the product of the current number of stack layers and the height of a single material, and calculate the first height of the upper surface of the previous material layer from the ground based on the current stack height and the pallet height.

3. The material palletizing method of the collaborative robot according to claim 2, It is characterized in that The first height is calculated by the following formula: ， in, Indicates the first height, Indicates the current number of stack layers. Indicates the height of a single material. Indicates the height of the pallet. ,in, Indicates the number of complete stack layers, , All are integers.

4. The material palletizing method of the collaborative robot according to claim 1, It is characterized in that Determining whether it is necessary to control the lifting column to rise according to the starting height of the lifting column and the first height includes: When the first height is less than or equal to the starting height of the lifting column, determining that there is no need to control the lifting column to rise; When the first height is greater than the starting height of the lifting column, it is determined that the lifting column needs to be controlled to rise.

5. The material palletizing method of the collaborative robot according to claim 1, It is characterized in that The optimal height of the lifting column is calculated by the following formula: ， in, Indicates the optimal height of the lifting column. Indicates the first height, Indicates the front height, Indicates the height of a single material. and The sum of represents the height of the preceding point. Indicates the maximum reachable height of the robot arm. Indicates the starting height of the lifting column.

6. The material palletizing method of the collaborative robot according to claim 1, It is characterized in that Optimizing the second height based on the optimal height of the lifting column includes: Obtaining the maximum travel height of the lifting column; The second height is optimized according to the optimal height of the lifting column and the maximum stroke height, wherein if the optimal height of the lifting column is less than the maximum stroke height, the second height is made equal to the optimal height of the lifting column; if the optimal height of the lifting column is greater than or equal to the maximum stroke height, the second height is made equal to the maximum stroke height.

7. The material palletizing method of the collaborative robot according to any one of claims 1 to 6, It is characterized in that Also includes: During the process of palletizing the current material layer, determining whether the inverse solution of the palletizing point of the current material fails; If the inverse solution of the stacking point of the current material fails, the stacking method of the current material layer is re-determined to obtain a determined stacking method; The movement of the robot arm is controlled according to the determined palletizing method to palletize the current material layer.

8. The material palletizing method of the collaborative robot according to claim 7, It is characterized in that The stacking method of the current material layer includes the stacking points of the current material and the stacking order of the current material layer. The stacking points of the current material include the entry point, the front point and the discharge point. Re-determine the palletizing method of the current material layer, including: Determine the stacking order of the current material layer, and determine the discharge point of the current material according to the determined stacking order, wherein the determined stacking order is from far to near in the perspective of the collaborative robot; Based on the determined discharge point, the leading point and the entry point of the current material are determined in sequence.

9. The material palletizing method of the collaborative robot according to claim 8, It is characterized in that Based on the determined discharge point, the leading point and the entry point of the current material are sequentially determined, including: Determine a preset height between the leading point and the upper surface of the previous material layer, and a preset distance between the leading point and the determined discharge point, wherein the preset height is less than the height of a single material; Determine the leading point of the current material based on the preset height and the preset distance; An entry point of the current material is determined based on the preceding point, wherein the determined entry point and the determined preceding point are located in the same horizontal plane, and a horizontal plane projection of the determined entry point does not overlap with a horizontal plane projection of the current stack type.

10. The material palletizing method of the collaborative robot according to claim 8, It is characterized in that Controlling the movement of the robot arm according to the determined palletizing method to palletize the current material layer includes: The materials of the current material layer are stacked according to the determined stacking order, wherein, for each of the materials, the robot arm is controlled to move axially to a determined entry point, linearly to a determined front point, and linearly to a determined discharge point in sequence to stack the material.

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