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CN-121995840-A - Cargo transportation control method based on PLC control technology

CN121995840ACN 121995840 ACN121995840 ACN 121995840ACN-121995840-A

Abstract

The invention discloses a cargo transportation control method based on a PLC control technology, which relates to the technical field of PLC control and comprises the steps of obtaining physical layout information of a cargo transportation system, including sensor position coordinates, power actuator interface numbers and cargo delivery platform coordinates, defining input and output mapping register areas in a PLC program editing environment according to the physical layout information, accessing corresponding physical sensor and power actuator control loops to specified addresses, constructing a logic control model in the PLC according to the physical layout information, dividing a transportation path into sequentially connected path control sections and specifying control logic subroutines for each section, receiving target platform instructions of an upper scheduling system, including unique cargo identifiers and target platform coordinates, and inputting the information into a PLC intermediate data register. The method improves the accuracy and flexibility of cargo transportation control, and is suitable for automatic cargo transportation scenes.

Inventors

  • WU SHUAI

Assignees

  • 山西速鑫物流有限公司

Dates

Publication Date
20260508
Application Date
20260410

Claims (10)

  1. 1. The cargo transportation control method based on the PLC control technology is characterized by comprising the following steps of: acquiring physical layout information of a cargo transportation system, wherein the physical layout information comprises position coordinates of a plurality of sensors distributed along a transportation path, interface numbers of power actuators and coordinate information of a cargo delivery platform; Defining an input mapping register area and an output mapping register area in a program editing environment of a Programmable Logic Controller (PLC) according to physical layout information of the cargo transportation system, connecting physical sensors corresponding to the position coordinates of the sensors to a designated address of the input mapping register area, and connecting a control loop corresponding to an interface number of the power actuator to the designated address of the output mapping register area; in the programmable logic controller PLC, a logic control model of a transport path is constructed according to the physical layout information, the logic control model divides the continuous transport path into a series of sequentially connected path control sections, and a corresponding control logic subroutine is designated for each path control section; receiving a target platform instruction of goods to be transported from an upper dispatching system, wherein the target platform instruction comprises a unique identifier of the goods to be transported and coordinate information of a specified goods handing-over platform; And recording the unique identifier of the goods to be transported and the coordinate information of the appointed goods delivery platform into an intermediate data register of the programmable logic controller PLC.
  2. 2. The cargo transportation control method based on the PLC control technology according to claim 1, further comprising: Based on the coordinate information of the appointed goods delivery platform, carrying out path planning by utilizing a logic control model of the transportation path, and calculating a complete driving sequence from a starting point to the appointed goods delivery platform for the goods to be transported, wherein the complete driving sequence comprises the following steps: inquiring coordinate information of the goods delivery platform, and determining a final logic node of the goods to be transported on a transport path; starting from the starting point, performing logic traversal in a logic control model of the transport path, and enumerating all paths from the starting point to a final logic node; comparing all enumerated paths according to a preset path judging strategy, wherein the path judging strategy comprises comprehensive evaluation indexes of the number of path control sections and the action complexity of a power actuator in a path; selecting the path with the optimal comprehensive evaluation index as a planned recommended path; Extracting a path control section list passed by the recommended path from a logic control model of the transportation path, and determining the passing sequence of each path control section according to the transportation direction; Packaging the path control section list and the passing sequence combination, generating the complete driving sequence and storing the complete driving sequence in a designated data block of the Programmable Logic Controller (PLC); The complete drive sequence is composed of a plurality of path control sections arranged according to a traffic sequence.
  3. 3. The cargo transportation control method based on PLC control technology according to claim 2, further comprising the step of executing the complete drive sequence: reading the complete driving sequence from a designated data block of the programmable logic controller PLC, and extracting a target path control section which is required to be activated currently; Invoking a control logic subroutine corresponding to the target path control section; Executing the control logic subprogram, wherein the control logic subprogram judges the occupation and idle conditions of the target path control section by scanning the sensor state related to the target path control section in the input image register area; When the scanning confirms that the target path control section is in an idle state, the control logic subprogram writes a driving signal into a power actuator control address corresponding to the target path control section in the output image register area, and starts the power actuator to drive goods into the target path control section.
  4. 4. The cargo transportation control method according to claim 3, wherein executing the control logic subroutine, the control logic subroutine determining occupancy and idleness of the target path control section by scanning sensor states associated with the target path control section in the input map register, comprises: The control logic subroutine periodically reads register bit states in the input shadow register associated with target path control segment ingress and egress sensors; Judging whether the goods to be transported completely enter or leave the target path control section according to the register bit state changes of the inlet sensor and the outlet sensor; Marking the internal state of the target path control section as occupied locking after the goods to be transported completely enter the target path control section but before leaving the target path control section completely; and after the goods to be transported completely leave the target path control section, switching the internal state of the target path control section into idle state, and releasing the occupation locking of the path control section.
  5. 5. The cargo transportation control method based on the PLC control technology according to claim 4, further comprising an operation monitoring step of cargo within the target path control section: Continuously monitoring status signals of monitoring sensors located inside the target path control section in the input shadow register during the target path control section being in an occupied locked state; Recording the triggering time and sequence of the state signals of the monitoring sensor, and comparing the triggering time and sequence with a preset standard operation time sequence template; triggering abnormal operation judgment when the deviation between the triggering time and sequence of the state signals of the monitoring sensor and the standard operation time sequence template exceeds a preset tolerance threshold; generating an abnormal event message containing an abnormal section identifier, an abnormal type code and an offset value; and storing the abnormal event message into a designated data block of the programmable logic controller PLC, immediately interrupting the currently executed complete driving sequence, and jumping the control flow of the programmable logic controller PLC to a preset abnormal processing program branch.
  6. 6. The cargo transportation control method based on the PLC control technology according to claim 5, wherein the step of jumping the control flow of the programmable logic controller PLC to a predetermined abnormality processing program branch includes: In the exception handler branch, firstly, reading an exception section identifier in the exception event message; according to the abnormal section identification, the power actuator which outputs the image register area to cause the goods to move is controlled to write a stop signal, so that the goods are stationary in the target path control section; Sending an interrupt notification containing the abnormal event message content to the upper scheduling system, and requesting manual intervention or a new scheduling instruction; After receiving an intervention completion confirmation or a new driving instruction from the upper dispatching system, resetting the driving target of the goods to be transported according to the new driving instruction, wherein the new driving instruction comprises continuous advancing, retracting the previous section or going to an emergency treatment station; And re-planning a path from the current interruption point, or continuing to execute the interrupted complete driving sequence according to the new driving instruction.
  7. 7. The method for controlling cargo transportation based on the PLC control technology according to claim 6, further comprising the step of concurrent transportation scheduling of a plurality of cargoes: In an intermediate data register of the programmable logic controller PLC, an independent transportation task instance is established for each piece of goods in a transportation state; each transport task instance comprises a unique identifier of the corresponding cargo, a target platform, a current path control section and a complete driving sequence independently planned for the corresponding cargo; Establishing a global path resource occupation table for all the activated transport task instances, and marking in real time which transport task instance each path control section occupies or is preempted in the global path resource occupation table; When the programmable logic controller PLC performs path planning for a new cargo to be transported so as to calculate a complete driving sequence of the cargo, the planning process needs to query the global path resource occupation table; In the calculated complete driving sequence, any path control section cannot be occupied by other transportation task examples in the global path resource occupancy table at the moment of being occupied by the new goods to be transported, or else, the whole path control section is re-planned or waited.
  8. 8. The method of claim 7, wherein creating a global path resource occupancy table for all active transport task instances, wherein marking in real time which transport task instance each path control section is occupied or preempted in the global path resource occupancy table comprises: Defining a multi-row data table in a system data block of the programmable logic controller PLC as the global path resource occupation table; each row of the global path resource occupancy table corresponds to one path control section, and each row contains an identifier of the path control section, a unique identifier of a transportation task instance currently occupying the path control section and future time slice information in which the path control section is preempted; writing a unique identifier of a transport task instance in a row corresponding to a path control section before one transport task instance is ready to enter the path control section, and marking the state as a preemption; Updating the state to be actual occupation after the transport task instance actually enters the path control section; After the transport task instance completely leaves the path control section, clearing the occupation information in the corresponding row, and setting the state as idle; the future time slice information is derived based on an execution progress estimate of the complete drive sequence for each transport task instance for conflict prediction.
  9. 9. The method for controlling cargo transportation based on the PLC control technology according to claim 8, further comprising the step of deadlock detection and release based on the global path resource occupancy table: Periodically analyzing all rows in a pre-occupied or actual occupied state in the global path resource occupation table, and constructing a resource allocation map; in the resource allocation oriented graph, nodes represent transportation task instances, and oriented edges represent path control sections of a transportation task instance occupying requests required by the next transportation task instance; detecting whether a ring exists in the resource allocation directed graph, and if so, judging that the system is subjected to logic deadlock; Once the logic deadlock is judged to occur, selecting one instance with the lowest priority from transport task instances forming a ring, withdrawing the latest path section occupation or preemption request, and forcing the latest path section occupation or preemption request to enter a waiting state; re-planning a path for the transport task instance forced into a waiting state and updating the global path resource occupancy table to break the logical deadlock.
  10. 10. The cargo transportation control method based on the PLC control technology according to claim 9, further comprising a closed loop processing step of completing a transportation task: After the Programmable Logic Controller (PLC) monitors that the goods to be transported reach the appointed goods delivery platform through a sensor, verifying whether the unique identifier of the goods to be transported is matched with information in the target platform instruction; after the matching is verified to be successful, an address of a loading and unloading mechanism corresponding to the platform is controlled to be written into an action signal in the output image register area, and cargo unloading or loading operation is triggered; Deleting a transport task instance corresponding to the goods to be transported from the intermediate data register after the goods unloading or loading operation is completed; Clearing the occupation marks of all path control sections related to the corresponding transport task instance; and sending a transport task completion confirmation message of the goods to be transported to the upper dispatching system, wherein the transport task completion confirmation message comprises a unique identifier, actual arrival time and platform identification of the goods to be transported.

Description

Cargo transportation control method based on PLC control technology Technical Field The invention belongs to the technical field of PLC control, and particularly relates to a cargo transportation control method based on a PLC control technology. Background In the cargo transportation system, the PLC control technology is widely applied to realizing automatic cargo transportation control, in the prior art, the PLC control is usually to directly connect a physical sensor and a power actuator into a preset input and output interface, and then realize the integral control of a transportation path by writing a fixed control program, so that the input and output mapping register area is defined in a targeted manner without combining specific physical layout information of the cargo transportation system. The prior art scheme has the defects that the access of the sensor and the power actuator is lack of correspondence with the physical layout of the system, the problems of interface docking confusion, signal transmission deviation and the like are easy to occur, so that a PLC control instruction cannot be matched with the actual transportation demand accurately, meanwhile, the transportation path adopts integral control logic, the continuous path is not subjected to sectional control, when the transportation path is complex or the control logic of a certain road section needs to be adjusted, the whole control program needs to be modified, the flexibility is poor, control logic conflict is easy to occur, and the accuracy and the efficiency of cargo transportation are influenced. The definition mode of the input/output image register area in the PLC control process is required to be optimized, the accurate butt joint of the sensor and the actuator is realized by combining the physical layout of the system, meanwhile, the control logic of the transportation path is improved, and the problems of insufficient flexibility and low control precision caused by integral control are solved. Disclosure of Invention The present invention aims to solve at least one of the technical problems existing in the prior art; therefore, the invention provides a cargo transportation control method based on a PLC control technology, which comprises the following steps: acquiring physical layout information of a cargo transportation system, wherein the physical layout information comprises position coordinates of a plurality of sensors distributed along a transportation path, interface numbers of power actuators and coordinate information of a cargo delivery platform; Defining an input mapping register area and an output mapping register area in a program editing environment of a Programmable Logic Controller (PLC) according to physical layout information of the cargo transportation system, connecting physical sensors corresponding to the position coordinates of the sensors to a designated address of the input mapping register area, and connecting a control loop corresponding to an interface number of the power actuator to the designated address of the output mapping register area; in the programmable logic controller PLC, a logic control model of a transport path is constructed according to the physical layout information, the logic control model divides the continuous transport path into a series of sequentially connected path control sections, and a corresponding control logic subroutine is designated for each path control section; receiving a target platform instruction of goods to be transported from an upper dispatching system, wherein the target platform instruction comprises a unique identifier of the goods to be transported and coordinate information of a specified goods handing-over platform; And recording the unique identifier of the goods to be transported and the coordinate information of the appointed goods delivery platform into an intermediate data register of the programmable logic controller PLC. Further, the method further comprises the following steps: Based on the coordinate information of the appointed goods delivery platform, carrying out path planning by utilizing a logic control model of the transportation path, and calculating a complete driving sequence from a starting point to the appointed goods delivery platform for the goods to be transported, wherein the complete driving sequence comprises the following steps: inquiring coordinate information of the goods delivery platform, and determining a final logic node of the goods to be transported on a transport path; starting from the starting point, performing logic traversal in a logic control model of the transport path, and enumerating all paths from the starting point to a final logic node; comparing all enumerated paths according to a preset path judging strategy, wherein the path judging strategy comprises comprehensive evaluation indexes of the number of path control sections and the action complexity of a power actuator in a path; selecting the path with t