A method, device and controller for lifting objects by coordinating two cranes

Abstract

The present application provides a method, device and controller for lifting a hoisted object by two cranes in coordination. The method, device and controller for lifting a hoisted object by two cranes in coordination provided by the present application calculate the control input through a sliding mode control algorithm, and then calculate the hoisting acceleration based on this, and control the hoisting according to the hoisting acceleration, so as to timely adjust the action of the crane in the presence of certainty and external interference, so that, on the one hand, the hook heights of the two cranes can be kept consistent, so that the hoisted object can be kept stable during the entire hoisting process, and the problem of tilting and instability of the hoisted object caused by height difference can be avoided; on the other hand, through control, the load balance can be maintained, and the hoisted object can be prevented from tilting or swinging during the hoisting and moving process, which can improve the safety and stability of the operation.

Description

Technical Field

[0001] The present application relates to the field of crane technology, and in particular to a method, device and controller for collaboratively lifting a load using two cranes. Background Art

[0002] Crane lifting operation is the process of using cranes to move heavy objects, and is widely used in construction, manufacturing, logistics, ports, mining and other fields.

[0003] When facing long, thin and light hoisting objects, the operating capacity of a single crane often cannot meet the operating requirements. For example, the hoisting object is prone to tilt and it is difficult to lift it smoothly. Therefore, the collaborative operation of two cranes is particularly important. When using two cranes to lift hoisting objects, how to achieve high coordination of the two cranes and smooth lifting of the hoisting objects is the key task of collaborative operation. Summary of the invention

[0004] In view of this, the present application provides a method, device and controller for collaboratively lifting a hoisted object using two cranes, so as to achieve high coordination of the two cranes when using the two cranes to lift the hoisted object, thereby achieving smooth lifting of the hoisted object to improve work efficiency and work safety.

[0005] Specifically, the present application is implemented through the following technical solutions:

[0006] In a first aspect, the present application provides a method for lifting a hoisted object by two cranes in coordination, the method being applied to a controller, the controller being used to control two cranes consisting of a first crane and a second crane, so as to control the two cranes to lift the hoisted object in coordination; the method comprising:

[0007] In the process of controlling the operation of the two cranes according to the pre-planned path, the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction is obtained, and a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object is obtained;

[0008] Calculate a position error vector according to the position vector at the current moment and the position vector at the previous moment, and calculate a control input vector according to the position error vector based on a sliding mode control algorithm; wherein the control input vector includes a control input amount corresponding to each crane;

[0009] For any one of the two cranes, calculating the winch change amount of the crane at the current moment according to the position error corresponding to the crane in the position error vector and the vertical distance of the hook of the crane relative to the hoisted object at the current moment;

[0010] Calculate the hoisting change amount of the crane at the next moment according to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment;

[0011] The acceleration of the hoisting of the crane is calculated according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment, and the crane is controlled according to the acceleration.

[0012] A second aspect of the present application provides a device for lifting a hoisted object by two cranes in cooperation, the device is applied to a controller, the controller is used to control two cranes consisting of a first crane and a second crane, so as to control the two cranes to lift the hoisted object in cooperation; the device includes an acquisition module, a calculation module and a control module; wherein,

[0013] The acquisition module is used to acquire the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction during the process of controlling the operation of the two cranes according to the pre-planned path, and obtain a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object;

[0014] The calculation module is used to calculate a position error vector according to a position vector at a current moment and a position vector at a previous moment, and calculate a control input vector according to the position error vector based on a sliding mode control algorithm; wherein the control input vector includes a control input amount corresponding to each crane;

[0015] The calculation module is further used to calculate, for any one of the two cranes, a winch change amount of the crane at a current moment according to the position error corresponding to the crane in the position error vector and a vertical distance of the hook of the crane relative to the hoisted object at a current moment;

[0016] The calculation module is further used to calculate the hoisting change amount of the crane at the next moment according to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment;

[0017] The calculation module is further used to calculate the acceleration of the hoisting of the crane according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment;

[0018] The control module is used to control the crane according to the acceleration.

[0019] A third aspect of the present application provides a controller for two cranes to collaboratively lift a hoisted object, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0020] The fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods provided in the first aspect of the present application.

[0021] The present application provides a method, device and controller for cooperatively lifting a hoisted object by two cranes. On the one hand, a sliding mode control algorithm is used to calculate the control input, and then the winch acceleration is calculated based on the control input, and the winch is controlled according to the winch acceleration, so as to timely adjust the action of the crane in the presence of certainty and external interference. In this way, on the one hand, the hook heights of the two cranes can be kept consistent, so that the hoisted object can be kept stable during the entire hoisting process, avoiding the problem of tilting and instability of the hoisted object caused by height difference; on the other hand, the load balance can be maintained to avoid tilting or swinging of the hoisted object during lifting and moving, which can improve the safety and stability of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a state diagram of a pair of cranes before the start of a lifting operation, showing an exemplary embodiment of the present application;

[0023] Figure 2 Flow chart of Embodiment 1 of the method for lifting a hoisted object by cooperating with two cranes provided in the present application;

[0024] Figure 3 A schematic diagram showing a method for calculating a winch variation according to an exemplary embodiment of the present application;

[0025] Figure 4 A flow chart of the second embodiment of the collaborative lifting of a hoisted object by two cranes provided in this application;

[0026] Figure 5 This is a schematic diagram of the implementation principle of grid division shown in an exemplary embodiment of the present application;

[0027] Figure 6 An exemplary embodiment of the present application shows the use of Flowchart of heuristic algorithm searching for dual-machine paths;

[0028] Figure 7A hardware structure diagram of the controller of the device for lifting objects by coordinating two cranes in this application;

[0029] Figure 8 This is a structural schematic diagram of Embodiment 1 of the device for lifting a load collaboratively using two cranes provided in the present application. DETAILED DESCRIPTION

[0030] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0031] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0032] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0033] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0034] Before introducing the method for lifting a hoisted object by cooperating with two cranes provided in the present application, the following is a brief introduction to the preparatory work before starting the operation.

[0035] Specifically, the method and device for collaboratively lifting a hoisted object by two cranes provided in the present application are applied to a controller, which is used to control a pair of cranes consisting of a first crane and a second crane to control the two cranes to collaboratively lift the hoisted object.

[0036] It should be noted that the controller can be a workstation independent of the crane, or a controller installed on the crane, which is not limited in the present application.

[0037] Figure 1 This is a status diagram of a pair of cranes before the start of a lifting operation, showing an exemplary embodiment of the present application.

[0038] For details, please refer to Figure 1 Before the lifting operation begins, the first crane and the second crane are initially located at their respective corresponding initial operating positions in an initial posture, and the first crane and the second crane operate in a peer operation mode (i.e., the first crane and the second crane have equal status and similar internal working principles).

[0039] It should be noted that the initial posture of the crane includes the position and posture of the crane. Among them, the position of the crane is the absolute position accurately measured by using the differential positioning technology RTK (Real-Time Kinematic, referred to as RTK) with the base station as the reference coordinate system. Furthermore, the posture of the crane is the relative posture calculated by the Vincenty algorithm (specifically, the relative posture refers to the relative posture between two cranes. In this application, the posture is characterized by the rotation angle and telescopic length).

[0040] It should be noted that the initial operating position of the two cranes is determined according to the size and weight of the hoisted object. In specific implementation, the distance between the two cranes can be adjusted according to the size and weight of the hoisted object to ensure that they can balance the load.

[0041] Furthermore, before starting the operation, the luffing mechanisms and basic arms of the two cranes can be fixed according to the operation angle and the hoisted object, so as to determine the direction of the cranes. It should be noted that the operation angle is set before the lifting operation begins. For example, in one possible implementation, if the target position is in the northeast direction, the operation angle can be set to the north or east direction. This is not limited in the present application.

[0042] In addition, before starting the operation, the telescopic lengths of the telescopic arms of the two cranes can be determined according to the requirements of the operation scene. During the lifting process, the lengths of the telescopic arms remain unchanged to ensure work safety. In specific implementation, the lengths of the telescopic arms of the cranes can be determined manually, which is not limited in this application.

[0043] It should be noted that in order to ensure the coordination of the operation, the two cranes involved in the collaborative operation need to synchronize the timestamps through the communication system. Since there is no special synchronization protocol standard for cranes, in this application, the positioning time signal of the GPS receiver is directly selected as the reference benchmark to uniformly calibrate the operation sequence. Furthermore, during the operation, the CAN-WIFI method is used to exchange position, speed, load and other data between the two cranes in real time.

[0044] Specifically, before starting the operation, the hoisting load can be reasonably distributed to each crane according to the load capacity of each crane. For example, in one possible implementation, the first initial vertical distance of the hook of the first crane relative to the hoisting object and the second initial vertical distance of the hook of the second crane relative to the hoisting object can be calculated according to the length between the two lifting ears of the hoisting object, the rated hoisting wire lifting force of the first crane, and the rated hoisting wire lifting force of the second crane, and then the initial operating positions of the two cranes can be determined accordingly.

[0045] Reference Figure 1 For the convenience of explanation, the crane on the left is recorded as the first crane A1, the crane on the right is recorded as the second crane A2, the lifting eye on the left side of the hoisted object is recorded as D1, and the lifting eye on the right side of the hoisted object is recorded as D2. In specific implementation, the first initial vertical distance and the second initial vertical distance can be calculated according to the following formula:

[0046] ,

[0047] in, p 10 is the first initial vertical distance of the first crane;

[0048] p 20 is the second initial vertical distance of the second crane;

[0049] p 0 It is the length between the two lifting eyes of the hoisted object;

[0050] F 1 is the rated wire lifting force of the first crane;

[0051] F 2 is the rated wire lifting force of the second crane.

[0052] Furthermore, before starting the operation, it is necessary to pre-plan the operation path, and then control the two cranes to start the operation according to the pre-planned path. In the process of controlling the operation of the two cranes, it is hoped that the lifting heights of the first crane and the second crane are consistent (i.e., highly coordinated), and then it is hoped that the load balance can be maintained and the hoisted object can be lifted steadily, that is, it is hoped that the vertical distance of the lifting lug of the first crane relative to the hoisted object and the vertical distance of the hook of the second crane relative to the hoisted object remain unchanged. Through the method provided in this application, the high coordination of the two cranes can be achieved, and the purpose of maintaining load balance and lifting the hoisted object steadily can be achieved.

[0053] The following is an introduction to the method for collaboratively lifting a load using two cranes provided in the present application.

[0054] Figure 2 This is a flow chart of the first embodiment of the method for lifting a load by cooperating with two cranes provided in this application. Figure 2 , which may include:

[0055] S201. In the process of controlling the operation of two cranes according to a pre-planned path, obtain the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction, and obtain a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object.

[0056] It should be noted that single-line laser radars (ydlidar) are placed at the two lifting ears of the hoisted object to measure the vertical distance between the edge of the hoisted object and the hook in the horizontal direction. Please continue to refer to Figure 1 , combined with the previous example, it can be understood that a single-line laser radar is placed at D1, which can measure the vertical distance B1 between the left edge of the hoisting object and the first crane in the horizontal direction, and a single-line laser radar is placed at D2, which can measure the vertical distance B2 between the right edge of the hoisting object and the second crane in the horizontal direction. Furthermore, based on B1 and the length of the hoisting object, the first vertical distance p1 of the hook of the first crane relative to the hoisting object can be calculated (that is, the first vertical distance is equal to half of the length of the hoisting object minus B1); similarly, based on B2 and the length of the hoisting object, the second vertical distance p2 of the hook of the second crane relative to the hoisting object can be calculated (that is, the second vertical distance is equal to half of the length of the hoisting object minus B2).

[0057] In this step, B1 and B2 measured by two single-line laser radars can be periodically obtained, and then the first vertical distance and the second vertical distance can be calculated based on B1 and B2. Further, after the first vertical distance and the second vertical distance are obtained, the position vector can be obtained based on them.

[0058] Referring to the above description, it can be understood that the position vector includes two elements, which are the first vertical distance p1 of the hook of the first crane relative to the hoisted object and the second vertical distance p2 of the hook of the second crane relative to the hoisted object. The vector of the position vector is P=[p1, p2].

[0059] S202. Calculate a position error vector according to the position vector at the current moment and the position vector at the previous moment, and calculate a control input vector according to the position error vector based on a sliding mode control algorithm; wherein the first control input vector includes a control input quantity corresponding to each crane.

[0060] Specifically, in the present application, the first vertical distance and the second vertical distance are maintained unchanged based on the lifting allocation algorithm, and the lifting allocation algorithm can be modeled as:

[0061] ,

[0062] in, , V, D are all two-dimensional vectors, represents the derivative of the position vector, V represents the velocity vector, U represents the control input vector, and D represents the vector corresponding to the external disturbance.

[0063] Specifically, the position error vector refers to the difference between the position vector at the previous moment and the position vector at the current moment, which is also a In specific implementation, the position vector at the current moment and the position vector at the previous moment can be differenced to obtain the position error vector.

[0064] It should be noted that the control input vector includes two elements, which are the control input u1 corresponding to the first crane and the control input u2 corresponding to the second crane. vector, that is, the control input vector U=[u1, u2].

[0065] In a specific implementation, in a possible implementation, the control input vector may be calculated in the following manner:

[0066] (1) Calculate a sliding mode switching vector according to the position error vector and a pre-constructed sliding mode switching function.

[0067] Specifically, the pre-built sliding mode switching function is built according to actual needs, and is not limited in the present application. For example, in a possible implementation, the pre-defined sliding mode switching function is:

[0068] ,

[0069] in, is the position error vector;

[0070] is the first-order time derivative of the position error vector;

[0071] is a positive design parameter.

[0072] In this step, each element in the position error vector can be substituted into the pre-built sliding mode switching function to obtain the corresponding sliding mode switching value, and then the sliding mode switching vector is obtained based on the calculated sliding mode switching value combination. It can be understood that the sliding mode switching vector is also a Vector.

[0073] (2) According to the sliding mode switching vector, an adaptive coefficient in a control law corresponding to the sliding mode switching function constructed in advance is updated to obtain an updated control law.

[0074] Specifically, in a possible implementation, the control law corresponding to the pre-built sliding switching function can be represented by the following formula:

[0075] ,

[0076] in, u To control the input quantity;

[0077] k is the adaptive coefficient;

[0078] S is the sliding mode switching value in the sliding mode switching vector.

[0079] Referring to the previous description, it can be understood that the control law includes an adaptive coefficient, which can be changed. In a specific implementation, in order to realize the adaptive function of the sliding mode control, in a possible implementation method, the adaptive coefficient in the control law corresponding to the pre-constructed sliding mode switching function can be updated according to the sliding mode switching vector to obtain an updated control law.

[0080] In a specific implementation, in one embodiment, the adaptive coefficient may be updated according to the following formula:

[0081] ,

[0082] in, is the derivative of the adaptive coefficient;

[0083] is a positive design parameter;

[0084] S is the sliding mode switching value in the sliding mode switching vector.

[0085] It can be understood that, in a specific implementation, for a certain crane, the adaptive coefficient corresponding to the crane can be calculated based on the sliding mode switching value corresponding to the crane in the sliding mode switching vector.

[0086] (3) Based on the updated control law, a control input vector is calculated according to the sliding mode switching value.

[0087] For the specific implementation, please refer to the previous introduction. For a certain crane, after calculating the adaptive coefficient corresponding to the crane, the sliding mode switching value corresponding to the crane can be substituted based on the adaptive coefficient corresponding to the crane and according to the updated control law, the control input corresponding to the crane can be calculated.

[0088] Furthermore, after the control inputs corresponding to the two cranes are calculated, the vector formed by the two control inputs is the control input vector. It should be noted that the function designed using the Lyapunov stability theory is as follows, which can be used to prove its convergence and stability. The design is as follows:

[0089] ,

[0090] in yes The ideal value of . Derivatively, we get:

[0091] .

[0092] Specifically, It reflects the deviation of the adaptive coefficient and is a small value; The velocity quantity should also be a small value, because no velocity is expected; for the above formula, as long as the disturbance d 1 is properly controlled and Big enough, then will be less than zero. , so the sliding mode stability can be proved.

[0093] It should be noted that the function designed by Lyapunov stability theory is essentially to control p The size of remains unchanged. If there is a disturbance, the control input vector U will be adaptively adjusted to implement the adjustment logic.

[0094] S203. For any one of the two cranes, calculate the winch change of the crane at the current moment according to the position error corresponding to the crane in the position error vector and the vertical distance of the hook of the crane relative to the hoisted object at the current moment.

[0095] Specifically, Figure 3 This is a schematic diagram of calculating the winch change amount shown in an exemplary embodiment of the present application, please refer to Figure 3 For a crane, the position error refers to the change in the horizontal direction of the crane hook relative to the hoisted object when the hoisted object is tilted. It should be noted that due to the time interval between two controls (i.e. The change in the crane's hook in the plane of the load is approximately equal to the change in the crane's hook in the horizontal direction relative to the load.

[0096] It should be noted that since the influence of the fixed line and other hooks is ignored when designing the control law, in order to ensure consistency, the influence of the fixed line and other hooks should also be ignored in the conversion of the control law and the winch variation. The control law actually controls the speed of the winch.

[0097] Specifically, for example, in one possible implementation, point A is the center of gravity of the hoisted object, point B is the position of the hook before the lifting operation begins, point C is the position of the hook after the hoisted object tilts during the lifting process, and point D is the center of gravity of the hoisted object after the hoisted object tilts during the lifting process.

[0098] In the process of two cranes working together to lift the load, the change in the winch and the position error (the change in the horizontal direction of the crane's hook relative to the load, that is, the horizontal movement of the hook) satisfy the following relationship:

[0099] ,

[0100] ,

[0101] in, p is the vertical distance between the crane hook and the hoisted object at the current moment;

[0102] is the position error corresponding to the crane in the position error vector, that is, the movement of the hook in the horizontal direction;

[0103] u To control the input quantity;

[0104] is the winch change of the crane at the current moment;

[0105] is the winch change of the crane at the next moment;

[0106] The time interval from the previous moment to the current moment.

[0107] Combined with the above introduction, in this step, the winch change can be calculated according to the following formula:

[0108] ,

[0109] in, is the winch change of the crane at the current moment;

[0110] pis the vertical distance between the crane hook and the hoisted object at the current moment;

[0111] is the position error corresponding to the crane in the position error vector.

[0112] S204. Calculate the hoisting change amount of the crane at the next moment based on the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment.

[0113] Combined with the above description, in specific implementation, the hoisting change amount of the crane at the next moment can be calculated according to the following formula:

[0114] ,

[0115] in, is the winch change of the crane at the next moment;

[0116] u is the control input quantity corresponding to the crane in the control input vector;

[0117] p is the vertical distance between the crane hook and the hoisted object at the current moment;

[0118] is the position error corresponding to the crane in the position error vector;

[0119] is the winch change of the crane at the current moment;

[0120] The time interval from the current moment to the previous moment.

[0121] S205, calculating the acceleration of the hoisting according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment, and controlling the crane according to the acceleration.

[0122] Specifically, when the program is implemented, (The time interval from the last moment to the current moment) is set manually. Therefore, in the specific implementation, the winch change amount of the crane at the current moment, the winch change amount of the crane at the next moment and , calculate the acceleration of the winch.

[0123] The method for cooperatively lifting a hoisted object by two cranes provided in this embodiment calculates the control input through a sliding mode control algorithm, and then calculates the hoisting acceleration based on the control input, and controls the hoisting according to the hoisting acceleration, so as to timely adjust the action of the crane in the presence of certainty and external interference. In this way, on the one hand, the hook heights of the two cranes can be kept consistent, so that the hoisted object can be kept stable during the entire hoisting process, avoiding the problem of tilting and instability of the hoisted object caused by height difference; on the other hand, the load balance can be maintained, and the hoisted object can be prevented from tilting or swinging during the lifting and moving process, which can improve the safety and stability of the operation.

[0124] Figure 4 This is a flow chart of the second embodiment of the two cranes cooperating to lift the hoisted object provided in this application. Figure 4 Based on the above embodiment, the planning method of the pre-planned path includes:

[0125] S401, dividing the working area into grids to obtain a grid map.

[0126] Specifically, Figure 5 This is a schematic diagram of the implementation principle of grid division shown in an exemplary embodiment of the present application, please refer to Figure 5 , in specific implementation, the grid division process may include:

[0127] (1) Determine the scope of the work area.

[0128] Specifically, the scope of the working area can be determined according to the operating range of the two cranes. For example, in one embodiment, the determined working area is The rectangular area.

[0129] (2) Define the grid size and calculate the number of grids based on the working area and grid size.

[0130] Specifically, the grid size is set according to actual needs and is not limited in this embodiment. For example, in a possible implementation, the grid size is Furthermore, when the grid size is known, the number of grids can be calculated according to the size of the action area and the grid size.

[0131] (3) Create a raster map.

[0132] Specifically, a grid map can be created based on the calculated number of grids. Further, in the grid map, grids of obstacles and boundaries are marked as impassable or invalid values. In this embodiment, obstacles and boundaries are set to ∞.

[0133] Furthermore, due to the limitation of the crane's motion function, it cannot move laterally, so the left and right areas in the grid map are also set to ∞.

[0134] Please note that, please refer to Figure 5 , Figure 5 The dark gray and light gray areas in the lower left corner are the coverage area of ​​the hoisted object and the coverage area of ​​the crane respectively. The black dots represent the points that the crane can reach, and the black areas are the obstacle coverage areas.

[0135] It should be noted that the coverage area of ​​a hoisted object refers to a certain range around the location of the hoisted object, usually centered on the hoisted object, taking into account the size of the hoisted object and the possible swing range. The coverage area of ​​the hoisted object determines the range of space that the hoisted object may affect. In actual operation, it is necessary to ensure that there are no obstacles or other objects that need to be avoided in the coverage area of ​​the hoisted object.

[0136] Furthermore, the coverage area of ​​a crane refers to the area that the crane can cover when working, which is usually based on the crane's range of motion and boom length. The coverage area of ​​a crane determines the range of operation and handling of the crane. In actual operation, the optimal working path and operation strategy can be determined based on the coverage area of ​​the crane.

[0137] S402: Using the grid map The heuristic algorithm searches for the dual-machine path to obtain an initial path; wherein each path point in the initial path is represented by the position of the rotation center.

[0138] Specifically, in this application, The cost function of the heuristic algorithm is given by the heuristic function H and exercise cost G Composition, let's first analyze the heuristic function H To introduce:

[0139] Specifically, in this embodiment, The heuristic function of the heuristic algorithm is defined as follows:

[0140] ,

[0141] in, and Respectively represent the x-coordinate and y-coordinate of the corner point i in the target area p;

[0142] and Represents the x-coordinate and y-coordinate of the current point;

[0143] The current point refers to the center point of the hoisted object and the coverage area of ​​the crane.

[0144] Furthermore, the motion cost is defined as follows:

[0145] .

[0146] Specifically, in a possible implementation, the straight-moving operation is simple, and its motion cost value is set to 1; the turning operation is complex, and its motion cost value is set to 1.41. In actual work, the motion cost value can be set according to the requirements of the lifting operation, and is not limited in this embodiment.

[0147] Figure 6 An exemplary embodiment of the present application shows the use of Flowchart of heuristic algorithm searching for dual-machine paths. In specific implementation, the dual-machine paths can be searched according to the following steps:

[0148] S601. Determine whether the two current points corresponding to the two cranes at the current moment and the preset lifting end point are reachable. If so, execute step S602; if not, execute step S607.

[0149] Specifically, the determination of whether it is reachable mainly involves determining whether the coverage area of ​​the hoisted object and the crane is larger than the obstacle spacing in the feasible route. If a dynamic obstacle suddenly appears near the target point and makes it impossible to transport, it will be stopped manually.

[0150] S602: Store the key-value pairs composed of the two current points and the hoisting area into a path table, and update the cost value of each grid point in the grid map.

[0151] In the specific implementation, the cost value of each grid point is updated according to the cost function mentioned above.

[0152] S603, searching for the grid point with the minimum cost, and updating the two current points corresponding to the two cranes according to the found grid point.

[0153] In specific implementation, the minimum cost point can be obtained according to the lifting constraint and the current point can be updated. The minimum cost point is The grid point with the minimum total cost of the evaluation function obtained by the heuristic algorithm.

[0154] S604, determine whether the lifting area reaches the lifting end point, if not, execute step S605, if yes, execute step S607.

[0155] S605, determine whether the two current points are reachable, if so, execute step S602, if not, execute S606.

[0156] S606, updating the cost of each grid point in the grid map, deleting the two current points from the path table, and resetting the two current points corresponding to the two cranes at the previous moment as the two current points corresponding to the two cranes at the current moment.

[0157] S607: End. Determine the pre-planned path according to the path table.

[0158] Determine whether the lifting area reaches the lifting end point. If it reaches the lifting end point, the path search process can be ended; if it does not reach it, the two machines determine whether their current points are reachable, mainly obstacle collision judgment and chassis feasibility movement judgment. If there is an unreachable point for the two machines, the lower grid map cost needs to be updated to indicate that the cost of this current point is ∞. In addition, a rollback operation is required, that is, the current point is deleted from the path sequence table and the previous point is used as the current point again. If the current points of both machines are reachable, continue to update the path.

[0159] S403: For each path point in the initial path, convert the path point into the terminal coordinates of the crane to obtain an intermediate path.

[0160] Specifically, each path point in the initial path is represented by the position of the rotation center, and the path point needs to be converted into the end coordinates of the crane. In specific implementation, the path point can be converted into the end coordinates of the crane according to the transformation matrix based on the forward kinematics solution. For example, in one embodiment, the path point can be converted into the end coordinates of the crane according to the first transformation matrix T1 from the slewing joint to the first joint of the boom, the second transformation matrix T2 from the first joint of the boom to the second joint, and the third transformation matrix T3 from the second joint to the end of the third joint.

[0161] It should be noted that the first conversion matrix T1, the second conversion matrix T2, and the third conversion matrix T3 can be obtained by using the DH modeling theory formula:

[0162] .

[0163] In the specific implementation, the values ​​of each joint can be substituted to calculate each transformation matrix. Specifically, for the rotary joint 1, let =0°, a=0, d=0, , we can get the first transformation matrix T1; for the elevation joint 2, let =90°, a=D, d=H, , we can get the second transformation matrix T2. For the extended joint 3, let =90°, a=0, d=L, =90°, which is the third transformation matrix T3.

[0164] It should be noted that, in the above formula, alpha and beta are the rotation angles of the current arm section compared to the previous arm section around the z-axis; L is the linear displacement along the z-axis. For a two-section telescopic arm, L is the superposition of the lengths of the two telescopic arms.

[0165] S404: Smoothing the intermediate path to obtain a smoothed path.

[0166] In specific implementation, for each path point in the intermediate path, the B-spline curve smoothing method can be used to smooth it. In the B-spline curve smoothing method, the processing method of point P is represented by the following formula:

[0167] ,

[0168] in, P i It is the middle path i Waypoints

[0169] It is i k-order B-spline basis functions;

[0170] t is a parameter that varies in the interval [0,1];

[0171] n is the total number of waypoints in the intermediate path;

[0172] The middle path i The result after smoothing of the path points.

[0173] It should be noted that the purpose of smoothing is to create an optimized path that meets the requirements and ensure the smoothness and accuracy of the robot arm's movement.

[0174] S405 , for each path point in the smoothed path, using inverse kinematics solution, convert the path point into a cylinder displacement to obtain the pre-planned path.

[0175] Specifically, referring to the above description, the inverse matrix of the first conversion matrix, the second conversion matrix and the third conversion matrix can be , calculate the displacement of each joint cylinder and obtain the pre-planned path.

[0176] The method provided in this embodiment provides a path planning method. On the one hand, it plans the path of two cranes as a whole, which can ensure the precise synchronization of the actions of the two cranes. On the other hand, by dividing the working area into grids and using The heuristic algorithm can ensure that the path planning is based on specific and computable spatial units, which can greatly improve the accuracy and reliability of path planning. Thirdly, by smoothing the path, the sudden changes and sharp turns of the path can be reduced, the violent movement of the robot arm can be reduced, and energy consumption can be reduced.

[0177] In addition, the initial path is first converted into an intermediate path based on forward kinematics, and then converted into the final path through inverse kinematics. In this way, on the one hand, the initial path point is converted into the terminal coordinates of the device through forward kinematics, taking into account the specific structure and kinematic characteristics of the device, so that the path planning is more in line with the actual device's motion capabilities and spatial limitations. On the other hand, the coordinates of the device's terminal are converted into specific control parameters through inverse kinematics conversion, ensuring that each path point can be accurately executed by the device, avoiding execution errors and infeasibility caused by directly using abstract path points.

[0178] Corresponding to the aforementioned embodiment of a method for lifting a hoisted object by two cranes in cooperation, the present application also provides an embodiment of a device for lifting a hoisted object by two cranes in cooperation.

[0179] The embodiment of the device for lifting a load by two cranes in cooperation in the present application can be applied to a controller. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, the processor of the controller in which it is located reads the corresponding computer program instructions in the non-volatile memory into the memory and runs them. From the hardware level, if Figure 7 As shown, it is a hardware structure diagram of the controller of the device for lifting objects by two cranes in this application. Figure 7 In addition to the processor, memory, network interface, and non-volatile memory shown, the controller where the device in the embodiment is located may also include other hardware according to the actual function of the device for lifting the hoisted objects by two cranes in coordination, which will not be described in detail.

[0180] Figure 8 This is a schematic diagram of the structure of the first embodiment of the device for lifting objects with two cranes in cooperation provided by the present application. Figure 8 The device provided in this embodiment includes an acquisition module 810, a calculation module 820 and a control module 830; wherein,

[0181] The acquisition module 810 is used to acquire the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction during the process of controlling the operation of the two cranes according to the pre-planned path, and obtain a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object;

[0182] The calculation module 820 is used to calculate the position error vector according to the position vector at the current moment and the position vector at the previous moment, and calculate the control input vector according to the position error vector based on the sliding mode control algorithm; wherein the control input vector includes the control input amount corresponding to each crane;

[0183] The calculation module 820 is further configured to calculate, for any one of the two cranes, a winch change amount of the crane at a current moment according to the position error corresponding to the crane in the position error vector and a vertical distance of the hook of the crane relative to the hoisted object at a current moment;

[0184] The calculation module 820 is further configured to calculate the hoisting change amount of the crane at the next moment according to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment;

[0185] The calculation module 820 is further used to calculate the acceleration of the hoisting of the crane according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment;

[0186] The control module 830 is used to control the crane according to the acceleration.

[0187] The device of this embodiment can be used to perform Figure 1 The steps, specific implementation principles and implementation processes of the method embodiment shown are similar and will not be repeated here.

[0188] Please continue to refer to Figure 7 The present application also provides a controller, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0189] The present application also provides a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the steps of any one of the methods provided in the present application are implemented.

[0190] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0191] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0192] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for lifting a load by using two cranes in coordination, characterized in that: The method for lifting a hoisted object by two cranes in cooperation is applied to a controller, and the controller is used to control two cranes consisting of a first crane and a second crane to control the two cranes to lift the hoisted object in cooperation; the method comprises: In the process of controlling the operation of the two cranes according to the pre-planned path, the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction is obtained, and a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object is obtained; Calculate a position error vector according to the position vector at the current moment and the position vector at the previous moment, and calculate a control input vector according to the position error vector based on a sliding mode control algorithm; wherein the control input vector includes a control input amount corresponding to each crane; For any one of the two cranes, calculating the winch change amount of the crane at the current moment according to the position error corresponding to the crane in the position error vector and the vertical distance of the hook of the crane relative to the hoisted object at the current moment; Calculate the hoisting change amount of the crane at the next moment according to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment; The acceleration of the hoisting of the crane is calculated according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment, and the crane is controlled according to the acceleration.

2. The method according to claim 1, characterized in that According to the position error vector, based on the sliding mode control algorithm, a control input vector is calculated, including: Calculating a sliding mode switching vector according to the position error vector and a pre-constructed sliding mode switching function; According to the sliding mode switching vector, updating the adaptive coefficient in the control law corresponding to the sliding mode switching function constructed in advance to obtain an updated control law; Based on the updated control law, the control input vector is calculated according to the sliding mode switching vector.

3. The method according to claim 2, characterized in that The sliding mode switching function is: ， Among them, the is the position error vector; Said is the first-order time derivative of the position error vector; Said is a positive design parameter.

4. The method according to claim 2, characterized in that: The updating of the adaptive coefficient in the control law corresponding to the pre-constructed sliding mode switching function according to the sliding mode switching vector includes: The adaptive coefficient is updated according to the following formula: ， Among them, the is the derivative of the adaptive coefficient; Said is a positive design parameter; Said S is the sliding mode switching value in the sliding mode switching vector.

5. The method according to claim 2, characterized in that: The calculating a control input vector based on the updated control law and according to the sliding mode switching vector comprises: Substitute the sliding mode switching value in the sliding mode switching vector into the updated control law to obtain the control input vector; wherein the updated control law is represented by the following formula: ， Among them, the k is the adaptive coefficient; Said S is the sliding mode switching value in the sliding mode switching vector.

6. The method according to claim 1, characterized in that The calculating the winch change amount of the crane at the current moment according to the position error corresponding to the crane in the position error vector and the vertical distance of the hook of the crane relative to the hoisted object at the current moment comprises: The winch change is calculated according to the following formula: ， Among them, the is the winch change of the crane at the current moment; Said p is the vertical distance between the crane hook and the hoisted object at the current moment; Said is the position error corresponding to the crane in the position error vector.

7. The method according to claim 1, characterized in that According to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment, the hoisting change amount of the crane at the next moment is calculated, including: Calculate the winch change of the crane at the next moment according to the following formula: ， Among them, the is the winch change of the crane at the next moment; Said u is the control input quantity corresponding to the crane in the control input vector; Said p is the vertical distance between the crane hook and the hoisted object at the current moment; Said is the position error corresponding to the crane in the position error vector; Said is the winch change of the crane at the current moment; Said The time interval from the current moment to the previous moment.

8. The method according to claim 1, characterized in that The planning method of the pre-planned path includes: Divide the working area into grids to obtain a grid map; Using the grid map The heuristic algorithm searches for the dual-machine path to obtain an initial path; wherein each path point in the initial path is represented by the position of the rotation center; For each path point in the initial path, convert the path point into the end coordinates of the crane to obtain an intermediate path; Smoothing the intermediate path to obtain a smoothed path; For each path point in the smoothed path, inverse kinematics is used to solve the path point and convert it into a cylinder displacement to obtain the pre-planned path.

9. A device for lifting objects by cooperating with two cranes, characterized in that: The device is applied to a controller, and the controller is used to control a pair of cranes consisting of a first crane and a second crane, so as to control the pair of cranes to collaboratively lift the hoisted object; the device includes an acquisition module, a calculation module and a control module; wherein, The acquisition module is used to acquire the vertical distance between the center of gravity of the hoisted object and the hooks of the two cranes in the horizontal direction during the process of controlling the operation of the two cranes according to the pre-planned path, and obtain a position vector composed of a first vertical distance of the hook of the first crane relative to the hoisted object and a second vertical distance of the hook of the second crane relative to the hoisted object; The calculation module is used to calculate a position error vector according to a position vector at a current moment and a position vector at a previous moment, and calculate a control input vector according to the position error vector based on a sliding mode control algorithm; wherein the control input vector includes a control input amount corresponding to each crane; The calculation module is further used to calculate, for any one of the two cranes, a winch change amount of the crane at a current moment according to a position error corresponding to the crane in the position error vector and a vertical distance of the hook of the crane relative to the hoisted object at a current moment; The calculation module is further used to calculate the hoisting change amount of the crane at the next moment according to the position error corresponding to the crane in the position error vector, the vertical distance of the hook of the crane relative to the hoisted object at the current moment, the hoisting change amount of the crane at the current moment, the control input amount corresponding to the crane in the control input vector, and the time interval from the current moment to the previous moment; The calculation module is further used to calculate the acceleration of the hoisting of the crane according to the hoisting change amount of the crane at the current moment and the hoisting change amount of the crane at the next moment; The control module is used to control the crane according to the acceleration.

10. A controller, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 8 when executing the program.

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