A master-slave control method and related equipment for the motor of the slewing mechanism of a portal crane

Abstract

The present application provides a master-slave control method and related equipment for the motor of the slewing mechanism of a gantry crane, and relates to the field of slewing drive mechanical control technology. The programmable logic controller first sends a first instruction to the first slewing frequency converter to ensure the operation of the first slewing motor. The controller reads the feedback parameters of the first slewing frequency converter and sends it as a second instruction to the second slewing frequency converter. This master-slave control method establishes a direct connection between the two slewing motors, so that the second slewing motor can be adjusted according to the actual operating state of the first slewing motor. In this way, the parameter changes during operation can be adapted in real time, thereby effectively improving the control accuracy and synchronization of the slewing mechanism, improving the overall performance and reliability of the gantry crane, and reducing the complexity and cost increase caused by the improvement of the mechanical structure.

Description

Technical Field

[0001] The present application relates to the technical field of rotary drive mechanical control, and in particular to a master-slave control method for a motor of a slewing mechanism of a portal crane and related equipment. Background Art

[0002] Portal cranes are key equipment in port loading and unloading operations, and their slewing mechanisms directly affect operating efficiency and accuracy. Usually, the slewing mechanism is driven by two motors through a rigid connection to achieve precise slewing of large cranes. However, in actual applications, due to factors such as uneven dock surfaces and differences in the motors themselves, the two motors are often subjected to unbalanced forces. One motor may be continuously overloaded while the other is underloaded, which not only affects the normal operation of the crane, but also shortens the life of the equipment.

[0003] To address this issue, relevant technologies mainly start from the perspective of mechanical structure optimization, such as improving the design of the slewing bearing, reducing the impact of uneven ground by adding buffer gaskets or adjusting the supporting structure; or using elastic couplings to absorb part of the load difference through their own elastic deformation.

[0004] However, although improvements in mechanical structure can alleviate the problem to a certain extent, they often increase the complexity and maintenance costs of the equipment. Summary of the invention

[0005] The present application provides a master-slave control method and related equipment for a gantry crane slewing mechanism motor, which are used to reduce the complexity and cost increase caused by mechanical structure improvements.

[0006] In a first aspect, the present application provides a master-slave control method for the motor of a slewing mechanism of a gantry crane, comprising: a programmable logic controller sends a first instruction to a first slewing inverter; when the programmable logic controller confirms that the first slewing inverter drives the first slewing motor to operate according to the first instruction, the programmable logic controller reads the first motor feedback state parameter of the first slewing inverter; the programmable logic controller sends the first motor feedback state parameter as a second instruction to the second slewing inverter; and the programmable logic controller confirms that the second slewing inverter drives the second slewing motor to operate according to the second instruction.

[0007] By adopting the above technical solution, the programmable logic controller first sends a first instruction to the first rotary inverter to ensure the operation of the first rotary motor. The controller reads the feedback parameters of the first rotary inverter and sends it as a second instruction to the second rotary inverter. This master-slave control method establishes a direct connection between the two rotary motors, so that the second rotary motor can be adjusted according to the actual operating status of the first rotary motor. In this way, the parameter changes during operation can be adapted in real time, thereby effectively improving the control accuracy and synchronization of the rotary mechanism, improving the overall performance and reliability of the portal crane, and reducing the complexity and cost increase caused by the improvement of the mechanical structure.

[0008] In combination with some embodiments of the first aspect, in some embodiments, after the programmable logic controller confirms that the first rotary frequency converter drives the first rotary motor to operate according to the first instruction, and reads the first motor feedback state parameter of the first rotary frequency converter, the method further includes: the programmable logic controller calculates the error between the first motor feedback state parameter and the first instruction; the programmable logic controller determines whether the error is greater than the error threshold; if it is greater than the error threshold, the programmable logic controller calculates the change in the control error; the calculation function of the change in the control error is: Δu = Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2 )] In the formula, Δu is the change of control error, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient, e(k) is the error, e(k-1) is the error of the previous control, and e(k-2) is the error of the previous two controls; the programmable logic controller applies the change of the control error to the first instruction to obtain a corrected first instruction; the programmable logic controller smoothes the corrected first instruction to obtain a smoothed first instruction; the calculation function of the smoothing process is: smoothed first instruction = α*corrected first instruction + (1-α)*first instruction 0<α<1 In the formula, α is the smoothing coefficient; the programmable logic controller sends the smoothed first instruction to the first inverter.

[0009] By adopting the above technical solution, the programmable logic controller calculates the error between the first motor feedback state parameter and the first instruction, and determines whether it exceeds the threshold value. If it exceeds, the change in the control error is calculated, and the deviation of the first motor can be calculated. Subsequently, this change is applied to the first instruction and smoothed. This processing can reduce the sudden change of the instruction, making the first motor respond more smoothly, forming a dynamic adjustment mechanism, which can effectively reduce the difference between the theoretical parameter (i.e., the first instruction issued) and the actual parameter (i.e., the first motor feedback state parameter), improve the control accuracy of the slewing mechanism, and thus improve the operating efficiency and accuracy of the portal crane.

[0010] In combination with some embodiments of the first aspect, in some embodiments, after the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, the method further includes: when the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, reading the second motor feedback state parameter of the second rotary inverter; the programmable logic controller calculates the synchronization error according to the first motor feedback state parameter and the second motor feedback state parameter; the calculation function for calculating the synchronization error is: εs = (P1-P2)-(R1-R2) where εs is the synchronization error, P1 is the first motor feedback state parameter, P2 is the second motor feedback state parameter, R1 is the first instruction, and R2 is the second instruction; when the synchronization error exceeds the preset synchronization threshold, the programmable logic controller compensates the control output of the second rotary inverter: the compensation calculation function is: R2 ， =R2+Kc×εs, where R2 ， is the second instruction after compensation, R2 is the second instruction, Kc is the compensation gain coefficient, and εs is the synchronization error; as the absolute value of the synchronization error increases, the compensation gain coefficient increases, and as the absolute value of the synchronization error decreases, the compensation gain coefficient decreases.

[0011] By adopting the above technical solution, the programmable logic controller reads the feedback parameters of the two rotary inverters and calculates the synchronization error. When the error exceeds the preset threshold, the control output of the second rotary inverter is dynamically compensated. The compensation calculation function takes into account the size of the synchronization error and introduces a dynamically adjusted compensation gain coefficient. This method can adaptively adjust the compensation strength according to the changing trend of the synchronization error, thereby more accurately controlling the synchronization of the two rotary motors and solving the residual asynchronism problem.

[0012] In combination with some embodiments of the first aspect, in some embodiments, after the programmable logic controller confirms that the second rotation inverter drives the second rotation motor to operate according to the second instruction, the method also includes: when the programmable logic controller confirms that the second rotation inverter drives the second rotation motor to operate according to the second instruction, the second motor feedback state parameter of the second rotation inverter is read; the programmable logic controller calculates whether the difference between the first motor feedback state parameter and the second motor feedback state parameter is greater than an error threshold; if it is greater than the error threshold, the programmable logic controller sends the second motor feedback state parameter to the first rotation inverter as a third instruction; the programmable logic controller confirms that the first rotation inverter drives the first rotation motor to operate according to the third instruction.

[0013] By adopting the above technical solution, the programmable logic controller compares the feedback state parameters of the two rotary motors. When the difference exceeds the threshold, not only the second rotary motor is adjusted, but also the feedback state parameters of the second motor are sent as new instructions to the first rotary inverter. This two-way adjustment method creates a dynamic balancing system, allowing the two rotary motors to adjust each other and jointly find the best operating state. This method can not only solve the residual asynchronism problem, but also improve the synchronization accuracy and overall control effect of the rotary mechanism, and improve the operating reliability and efficiency of the portal crane.

[0014] In combination with some embodiments of the first aspect, in some embodiments, the first instruction includes a preset speed and a preset direction; the first motor feedback state parameters include the actual speed, actual torque, actual current, and actual running direction of the first rotary motor.

[0015] By adopting the above technical solution, the preset speed and direction are used as the control benchmark, while the feedback parameters such as actual speed, torque, current and running direction provide comprehensive information on the actual operating status of the motor. This detailed parameter setting and feedback mechanism enables the system to accurately evaluate the operating status of the motor and promptly detect and correct deviations.

[0016] In the second aspect, the present application provides a master-slave control method for the motor of the slewing mechanism of a gantry crane, including: when the first slewing inverter receives a first instruction sent by a programmable logic controller, it drives the first slewing motor to operate according to the first instruction; the first slewing inverter detects the feedback state parameters of the first motor after the operation of the first slewing motor; the first slewing inverter sends the feedback state parameters of the first motor as a second instruction to the second slewing inverter; the first slewing inverter confirms that the second slewing inverter drives the second slewing motor to operate according to the second instruction.

[0017] By adopting the above technical solution, a direct data transmission mechanism is established. The first-turn inverter directly sends its feedback state parameters as instructions to the second-turn inverter, bypassing the intermediate link of the programmable logic controller. This direct communication method significantly reduces the time delay of data transmission and improves the real-time performance of control. Since the multiple transmissions of data between different devices are reduced, the response speed is improved and the asynchrony caused by control lag is reduced.

[0018] In combination with some embodiments of the second aspect, in some embodiments, it includes: the first inverter and the second inverter are short-circuited.

[0019] By adopting the above technical solution, a direct physical connection is established between the first converter and the second converter. This short-circuit design simplifies the data transmission path and eliminates the time delay in the signal transmission process.

[0020] In a third aspect, the present application provides a slewing mechanism for a gantry crane, the slewing mechanism for the gantry crane comprising: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program codes, the computer program codes include computer instructions, and the one or more processors call the computer instructions to enable the slewing mechanism for the gantry crane to execute the method described in the first aspect and any possible implementation method of the first aspect.

[0021] In a fourth aspect, the present application provides a computer program product comprising instructions, which, when run on a slewing mechanism of a portal crane, enables the slewing mechanism of the portal crane to execute the method described in the first aspect and any possible implementation of the first aspect.

[0022] In a fifth aspect, the present application provides a computer-readable storage medium comprising instructions, which, when executed on a slewing mechanism of a gantry crane, causes the slewing mechanism of the gantry crane to execute the method described in the first aspect and any possible implementation of the first aspect.

[0023] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0024] 1. The programmable logic controller first sends the first instruction to the first rotary inverter to ensure the operation of the first rotary motor. The controller reads the feedback parameters of the first rotary inverter and sends it as the second instruction to the second rotary inverter. This master-slave control method establishes a direct connection between the two rotary motors, so that the second rotary motor can be adjusted according to the actual operating status of the first rotary motor. In this way, it can adapt to the parameter changes in operation in real time, thereby effectively improving the control accuracy and synchronization of the rotary mechanism, improving the overall performance and reliability of the portal crane, and reducing the complexity and cost increase caused by the improvement of the mechanical structure.

[0025] 2. The programmable logic controller calculates the error between the first motor feedback state parameter and the first instruction, and determines whether it exceeds the threshold. If it exceeds, the change in the control error is calculated, and the deviation of the first motor can be calculated. Subsequently, this change is applied to the first instruction and smoothed. This process can reduce the sudden change of the instruction, making the first motor respond more smoothly, forming a dynamic adjustment mechanism, which can effectively reduce the difference between the theoretical parameter (i.e., the first instruction issued) and the actual parameter (i.e., the first motor feedback state parameter), improve the control accuracy of the slewing mechanism, and thus improve the operating efficiency and accuracy of the portal crane.

[0026] 3. The programmable logic controller reads the feedback parameters of the two rotary inverters and calculates the synchronization error. When the error exceeds the preset threshold, the control output of the second rotary inverter is dynamically compensated. The compensation calculation function takes into account the size of the synchronization error and introduces a dynamically adjusted compensation gain coefficient. This method can adaptively adjust the compensation strength according to the changing trend of the synchronization error, thereby more accurately controlling the synchronization of the two rotary motors and solving the residual asynchronism problem.

[0027] 4. The programmable logic controller compares the feedback state parameters of the two rotary motors. When the difference exceeds the threshold, not only the second rotary motor is adjusted, but also the feedback state parameters of the second motor are sent as new instructions to the first rotary inverter. This two-way adjustment method creates a dynamic balancing system, allowing the two rotary motors to adjust each other and jointly find the best operating state. This method can not only solve the residual asynchronism problem, but also improve the synchronization accuracy and overall control effect of the rotary mechanism, and improve the operating reliability and efficiency of the portal crane. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a master-slave control method of a slewing mechanism motor of a portal crane in an embodiment of the present application;

[0029] Figure 2 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0030] Figure 3 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0031] Figure 4 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0032] Figure 5 It is a flow chart of another master-slave control method of the motor of the slewing mechanism of a portal crane in an embodiment of the present application;

[0033] Figure 6 It is a schematic diagram of an exemplary hardware structure of the slewing mechanism of the portal crane in the embodiment of the present application. DETAILED DESCRIPTION

[0034] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to be used as limitations to the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of", "said", "above", "the" and "this" are intended to also include plural expressions, unless there is a clear indication to the contrary in the context. It should also be understood that the term "and / or" used in the present application refers to and includes any or all possible combinations of one or more listed items.

[0035] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as suggesting or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features, and in the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0036] Before explaining the embodiments of the present application, it is necessary to have a deep understanding of the imbalance phenomenon and its root cause that may occur when the slewing mechanism is driven by two motors.

[0037] From the perspective of electrical control, the two motors are driven by two inverters, which communicate with the PLC system. The PLC is responsible for giving the speed frequency and direction of operation, and the inverter drives the motor according to these instructions. However, even motors or inverters of the same model and specification will inevitably have slight differences in the production process, which means that even if the same instruction rate is received (such as an input frequency of 50Hz), the actual output of the two inverters may be slightly different. For example, one motor may run at a frequency of 51Hz, while the other runs at 49Hz. This difference will cause one motor to run slightly faster and the other slightly slower.

[0038] Since the two rotary motors are rigidly connected to the large rotary bearing, and the motor's drive pinion acts directly on the large rotary ring gear, the faster-running motor will bear a greater load and output, while the slower-running motor will have a relatively smaller load and output. This unbalanced state will worsen over time.

[0039] From the perspective of mechanical structure, differences in the equipment manufacturing process can also lead to imbalance. For example, the pinion of one motor may have better precision and a smaller gap with the rotating large ring gear, while the other may have a larger gap. In addition, the center of gravity and center of the entire rotary mechanism may not be located at the balance position of the two motors, but closer to one of them. This structural asymmetry will cause one motor to bear greater force, while the other is relatively relaxed. In long-term operation, these unbalanced factors will cause a series of problems. One of the motors may be frequently in an overloaded drive state, accelerating its fatigue loss. At the same time, the inverter corresponding to the motor that bears a larger load will also be in a full-load or overloaded operation state for a long time, significantly shortening its service life.

[0040] refer to Figure 1 , Figure 1 It is a flow chart of a master-slave control method of a slewing mechanism motor of a portal crane in an embodiment of the present application;

[0041] S101, the programmable logic controller sends a first instruction to the first inverter;

[0042] It should be noted that the first instruction represents a code preset by relevant personnel or automatically generated by the system for controlling the operating parameters of the first motor and the second motor. These codes usually include key parameters such as the desired motor operating speed, direction, acceleration, etc.

[0043] In some embodiments, the PLC first generates a first instruction including information such as target speed and running direction according to preset running requirements or external inputs. Then, the PLC sends this instruction to the first rotary inverter through a pre-configured communication interface (such as Profibus or Modbus) to start or adjust the running state of the first rotary motor, laying the foundation for subsequent synchronous control.

[0044] S102, when the programmable logic controller confirms that the first rotary inverter drives the first rotary motor to operate according to the first instruction, the programmable logic controller reads the first motor feedback state parameter of the first rotary inverter;

[0045] This step is performed within a short time after S101 is executed, and is used to verify the effect of instruction execution and obtain necessary operation data.

[0046] In some embodiments, the PLC first confirms that the first rotary motor has started running according to the instruction by querying the status register of the first rotary inverter or receiving the status information actively sent by it. After successful confirmation, the PLC immediately sends a data read request to obtain the current motor operating parameters from the first rotary inverter, which may include key information such as actual operating speed, output current, output frequency, torque, etc.

[0047] The first instruction includes a preset speed and a preset direction;

[0048] The first motor feedback state parameters include the actual speed, actual torque, actual current, and actual running direction of the first rotary motor.

[0049] It should be noted that, in some embodiments, the input data (first instruction) and the output data (first motor feedback state parameter) are different in type and quantity. This design reflects the process from simple control to precise synchronization. The initial first instruction only contains basic speed and direction information, which provides a starting point. The feedback state parameters are more comprehensive and contain more operating details. By providing more state parameters, the second rotary motor can more accurately imitate the operating state of the first rotary motor, thereby achieving a higher degree of synchronization.

[0050] It can be seen that the preset speed and direction are used as the control benchmark, while the feedback parameters such as actual speed, torque, current and running direction provide comprehensive information about the actual operating status of the motor. This detailed parameter setting and feedback mechanism enables the system to accurately evaluate the operating status of the motor and promptly detect and correct deviations.

[0051] S103, the programmable logic controller sends the first motor feedback state parameter as a second instruction to the second inverter;

[0052] In some embodiments, the PLC first performs necessary processing and conversion on the feedback state parameters read from the first rotary frequency converter, then the PLC packages the processed parameters into an instruction format suitable for receipt by the second rotary frequency converter, and finally, the PLC sends the newly generated second instruction to the second rotary frequency converter through a preconfigured communication channel, in order to enable the second rotary motor to follow the operating status of the first rotary motor.

[0053] S104, the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction.

[0054] In some embodiments, the PLC first confirms that the second rotary motor has started running according to the second instruction by querying the status register of the second rotary frequency converter or receiving the status information actively sent by it. The PLC may compare the actual operating parameters of the second rotary motor with the actual operating parameters of the first rotary motor to verify whether the two motors have reached the expected synchronization state. If the confirmation is successful, the PLC may update the internal system status to indicate that the synchronization control process has been completed; if the confirmation fails, the PLC may start a predefined error handling procedure.

[0055] It can be seen that the programmable logic controller first sends the first instruction to the first rotary inverter to ensure the operation of the first rotary motor. The controller reads the feedback parameters of the first rotary inverter and sends it as the second instruction to the second rotary inverter. This master-slave control method establishes a direct connection between the two rotary motors, so that the second rotary motor can be adjusted according to the actual operating status of the first rotary motor. In this way, the parameter changes during operation can be adapted in real time, thereby effectively improving the control accuracy and synchronization of the rotary mechanism, improving the overall performance and reliability of the portal crane, and reducing the complexity and cost increase caused by the improvement of the mechanical structure.

[0056] During the actual operation, there is a difference between the theoretical parameters of the first rotary motor (i.e. the first instruction issued) and the actual parameters (i.e. the feedback state parameters of the first motor). This parameter deviation directly leads to less than ideal control accuracy of the rotary mechanism, which may affect the operating efficiency and accuracy of the entire gantry crane.

[0057] See also Figure 2 , Figure 2 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0058] Therefore, in some embodiments, after step S102, the method further includes: 201, a programmable logic controller calculates an error between a first motor feedback state parameter and a first instruction;

[0059] In some embodiments, the PLC first extracts the content of the first instruction sent previously from the internal memory, and then compares it with the newly received first motor feedback state parameter. The comparison process may involve multiple parameters, such as speed, position, current, etc. The PLC uses a predefined calculation method (such as difference, ratio or complex mathematical model) to quantify the difference between these parameters, and finally obtains one or more numerical values ​​representing the error.

[0060] In some embodiments, the first motor feedback state parameter and the first instruction each include a plurality of data items. In this case, the PLC compares the first motor feedback state parameter with the corresponding data items of the first instruction one by one and calculates the error.

[0061] 202. The programmable logic controller determines whether the error is greater than an error threshold;

[0062] 203. If it is greater than the error threshold, the programmable logic controller calculates the change in the control error;

[0063] The calculation function of the change in control error is:

[0064] Δu=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2)]

[0065] Wherein, Δu is the change of control error, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient, e(k) is the error, e(k-1) is the error of the previous control, and e(k-2) is the error of the previous two controls;

[0066] In some embodiments, the PLC first confirms that the error has indeed exceeded the threshold, then the PLC calls the pre-configured PID control algorithm, substitutes the current error value e(k) and the previously saved error history values ​​e(k-1) and e(k-2) into the formula, and the PLC also reads the Kp, Ki and Kd values ​​under the current working conditions from the system parameter library. Finally, the PLC calculates the change in the control error Δu according to the formula, and this value will be used for subsequent control instruction corrections.

[0067] 204. The programmable logic controller applies the change in the control error to the first instruction to obtain a corrected first instruction;

[0068] In some embodiments, the PLC first extracts the original first instruction content from the internal memory, and then the PLC performs a mathematical operation (usually addition or multiplication) on the control error change Δu calculated in S203 and the original instruction. This process may involve simultaneous adjustment of multiple control parameters, such as speed, position, acceleration, etc. The PLC needs to ensure that the corrected instruction value is still within the range allowed by the system, and perform a limiting process when necessary. Finally, the PLC generates a new instruction data structure containing all corrected parameter values.

[0069] In some specific embodiments, the PLC reads the complete content of the original first instruction from the instruction buffer; the PLC parses the original instruction and extracts the specific parameter values ​​that need to be corrected; the PLC distributes the control error change Δu to each parameter that needs to be corrected according to a predetermined ratio; the PLC performs correction calculations on each parameter, such as new speed value = original speed value + speed correction amount; the PLC checks each corrected parameter value to ensure that they are within the range allowed by the system and limits them when necessary; the PLC reassembles the corrected parameter values ​​to generate a new instruction data packet, which is not limited here.

[0070] 205. The programmable logic controller performs smoothing processing on the corrected first instruction to obtain a smoothed first instruction; the calculation function of the smoothing processing is:

[0071] Smoothed first instruction = α * modified first instruction + (1-α) * first instruction 0<α<1

[0072] In the formula, α is the smoothing coefficient;

[0073] In some embodiments, the PLC performs weighted average calculation on the revised first instruction and the instruction sent last time. The calculation adopts the principle of sliding average, and the new instruction value is obtained by the weighted combination of the current revised value and the historical value.

[0074] 206. The programmable logic controller sends the smoothed first instruction to the first inverter.

[0075] It can be seen that the programmable logic controller calculates the error between the first motor feedback state parameter and the first instruction, and determines whether it exceeds the threshold. If it exceeds, the change in the control error is calculated, and the deviation of the first motor can be calculated. Subsequently, this change is applied to the first instruction and smoothed. This processing can reduce the sudden change of the instruction, making the first motor respond more smoothly, forming a dynamic adjustment mechanism, which can effectively reduce the difference between the theoretical parameter (i.e., the first instruction issued) and the actual parameter (i.e., the first motor feedback state parameter), improve the control accuracy of the slewing mechanism, and thus improve the operating efficiency and accuracy of the portal crane.

[0076] In actual use, preliminary synchronization optimization has been implemented, solving the main synchronization problem between the first and second rotary motors. Although the main synchronization problem has been solved, there is still a certain degree of asynchronism between the two rotary motors under certain operating conditions.

[0077] See also Figure 3 , Figure 3 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0078] Therefore, in some embodiments, after step S104, the following steps are further included:

[0079] S301, when the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, the second motor feedback state parameter of the second rotary inverter is read;

[0080] It should be noted that the principle and process of this step are similar to those of step S102. For the relevant principle and process, refer to step S102 and are not limited here.

[0081] S302, the programmable logic controller calculates a synchronization error according to the first motor feedback state parameter and the second motor feedback state parameter;

[0082] The calculation function for calculating the synchronization error is:

[0083] εs=(P1-P2)-(R1-R2)

[0084] Wherein, εs is the synchronization error, P1 is the first motor feedback state parameter, P2 is the second motor feedback state parameter, R1 is the first instruction, and R2 is the second instruction;

[0085] The first motor feedback state parameter represents a data set reflecting the actual operating state of the first rotary motor read from the first rotary frequency converter. The second motor feedback state parameter represents a data set reflecting the actual operating state of the second rotary motor read from the second rotary frequency converter. The synchronization error refers to the difference between the actual operating states of the two motors.

[0086] In some embodiments, after obtaining the feedback state parameters of the first motor and the second motor, the PLC uses a predefined calculation function to calculate the synchronization error. This calculation process takes into account the actual operating parameters of the two motors and their respective control instructions to evaluate the degree of synchronization between the two motors. The calculation function not only compares the actual state difference of the two motors, but also takes into account their deviations from their respective control instructions, thereby deriving a comprehensive synchronization error value.

[0087] S303: When the synchronization error exceeds the preset synchronization threshold, the programmable logic controller compensates the control output of the second inverter:

[0088] The calculation function of compensation is:

[0089] R2 ， =R2+Kc×εs

[0090] In the formula, R2 ， is the second instruction after compensation, R2 is the second instruction, Kc is the compensation gain coefficient, and εs is the synchronization error; as the absolute value of the synchronization error increases, the compensation gain coefficient increases, and as the absolute value of the synchronization error decreases, the compensation gain coefficient decreases.

[0091] In some embodiments, the PLC first compares the calculated synchronization error with a preset synchronization threshold. If the synchronization error exceeds the threshold, it means that the synchronization degree of the two motors has exceeded the acceptable range and needs to be adjusted. At this time, the PLC will start the compensation mechanism and calculate a compensation value according to the size and direction of the synchronization error. This compensation value will be added to the original second instruction to form a new control output, which will be sent to the second rotary inverter to adjust the operating state of the second rotary motor, thereby reducing the synchronization error.

[0092] In some specific embodiments, the PLC first calculates the difference between the synchronization error and a preset threshold; then calculates the compensation amount based on the difference and a predefined compensation function; finally, the compensation amount is superimposed on the original second instruction to generate a new control output, which is not limited here.

[0093] It can be seen that the programmable logic controller reads the feedback parameters of the two rotary inverters and calculates the synchronization error. When the error exceeds the preset threshold, the control output of the second rotary inverter is dynamically compensated. The compensation calculation function takes into account the size of the synchronization error and introduces a dynamically adjusted compensation gain coefficient. This method can adaptively adjust the compensation strength according to the changing trend of the synchronization error, thereby more accurately controlling the synchronization of the two rotary motors and solving the residual asynchronism problem.

[0094] In actual use, preliminary synchronization optimization has been implemented, solving the main synchronization problem between the first and second rotary motors. Although the main synchronization problem has been solved, there is still a certain degree of asynchronism between the two rotary motors under certain operating conditions.

[0095] See also Figure 4 , Figure 4 It is another flow chart of the master-slave control method of the motor of the slewing mechanism of the portal crane in the embodiment of the present application;

[0096] Therefore, in some embodiments, after step S104, the following steps are further included:

[0097] S401, when the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, the programmable logic controller reads the second motor feedback state parameter of the second rotary inverter;

[0098] It should be noted that the principle and process of this step are similar to those of step S102. For the relevant principle and process, refer to step S102 and are not limited here.

[0099] S402, the programmable logic controller calculates whether the difference between the first motor feedback state parameter and the second motor feedback state parameter is greater than an error threshold;

[0100] In some embodiments, after obtaining the feedback state parameters of the first motor and the second motor, the PLC will immediately perform parameter comparison. The comparison process first involves selecting key state parameters, such as speed, position or torque. Then, the PLC will calculate the difference between these selected parameters, and the calculated difference will be compared with a pre-set error threshold, which is usually predetermined according to system requirements and operating conditions. The purpose of the comparison is to determine whether the operating status of the two motors is within an acceptable synchronization range.

[0101] In some specific embodiments, the PLC first extracts the same type of data (such as rotational speed) from the feedback state parameters of the first motor and the second motor; then calculates the absolute difference of these data; then compares the calculated difference with a preset error threshold; and finally generates a judgment result based on the comparison result, which is not limited here.

[0102] S403, if it is greater than the error threshold, the programmable logic controller sends the second motor feedback state parameter as a third instruction to the first inverter;

[0103] In some embodiments, this step is triggered when the PLC determines that the difference between the feedback state parameters of the first motor and the second motor exceeds a preset error threshold. This means that the operating states of the two motors have become significantly out of sync. In order to correct this out of sync state, the PLC will take measures to make the operating state of the first rotary motor consistent with that of the second rotary motor. Specifically, the PLC directly uses the feedback state parameters of the second motor just read as a new control instruction (i.e., the third instruction) and sends it to the first rotary inverter. This is actually a master-slave control strategy, in which the second rotary motor is regarded as the master and the first rotary motor is followed as the slave.

[0104] S404, the programmable logic controller confirms that the first rotary inverter drives the first rotary motor to operate according to the third instruction.

[0105] It can be seen that the programmable logic controller compares the feedback state parameters of the two rotary motors. When the difference exceeds the threshold, not only the second rotary motor is adjusted, but also the feedback state parameters of the second motor are sent as new instructions to the first rotary inverter. This two-way adjustment method creates a dynamic balance system, allowing the two rotary motors to adjust each other and jointly find the best operating state. This method can not only solve the residual asynchronism problem, but also improve the synchronization accuracy and overall control effect of the rotary mechanism, and improve the operating reliability and efficiency of the portal crane.

[0106] In actual use, in practical applications, the data flow process is usually as follows: the first-turn inverter obtains the feedback state parameters of the first motor and then sends these parameters to the programmable logic controller (PLC). The PLC receives and processes these data and then sends the processed data as instructions to the second-turn inverter. Since the first-turn inverter and the second-turn inverter need to maintain synchronous operation, this multi-step data transmission process may cause the data flow time to be extended, thereby affecting the synchronization accuracy.

[0107] See also Figure 5 , Figure 5 It is a flow chart of another master-slave control method of the motor of the slewing mechanism of a portal crane in an embodiment of the present application;

[0108] Therefore, in some embodiments, a new master-slave control method for the motor of the slewing mechanism of a portal crane is provided.

[0109] S501: When the first rotary frequency converter receives a first instruction sent by the programmable logic controller, the first rotary motor is driven to operate according to the first instruction;

[0110] In some embodiments, the first rotary frequency converter first parses the received first instruction and extracts the control parameters contained therein, such as target speed, running direction, etc. Then, the frequency converter generates corresponding voltage and frequency outputs according to these parameters, and transmits these electrical signals to the first rotary motor through the power electronic device.

[0111] S502, the first rotary frequency converter detects a first motor feedback state parameter after the first rotary motor runs;

[0112] In some embodiments, the first inverter collects the motor's operating data in real time through various built-in sensors and measurement circuits. These data include but are not limited to the motor's speed, current, voltage, power factor, etc. The inverter processes and calculates the collected raw data and converts it into meaningful physical quantities, such as speed, torque, etc.

[0113] S503, the first rotary inverter sends the first motor feedback state parameter as the second instruction to the second rotary inverter; in some embodiments, the first rotary inverter directly sends the just collected operation state data of the first rotary motor as the control instruction to the second rotary inverter. This method can quickly synchronize the operation state of the first rotary motor to the second rotary motor, so that the two motors maintain the same operation state.

[0114] S504: The first rotating inverter confirms that the second rotating inverter drives the second rotating motor to operate according to the second instruction.

[0115] In some embodiments, the first rotary inverter needs to verify whether the second rotary inverter has successfully received the second instruction and whether it has correctly driven the second rotary motor to operate according to the instruction.

[0116] It can be seen that a direct data transmission mechanism has been established. The first-turn inverter directly sends its feedback state parameters as instructions to the second-turn inverter, bypassing the intermediate link of the programmable logic controller. This direct communication method significantly reduces the time delay of data transmission and improves the real-time performance of control. Since the multiple transmissions of data between different devices are reduced, the response speed is improved and the asynchrony caused by control lag is reduced.

[0117] In some embodiments, the first inverter is short-circuited with the second inverter.

[0118] It can be seen that a direct physical connection is established between the first-converter converter and the second-converter converter. This short-circuit design simplifies the data transmission path and eliminates the time delay in the signal transmission process.

[0119] The following introduces an exemplary portal crane slewing mechanism 600 provided in an embodiment of the present application. Figure 6 It is a schematic diagram of an exemplary hardware structure of a portal crane slewing mechanism 600 provided in an embodiment of the present application.

[0120] In some embodiments, the portal crane slewing mechanism 600 is a computer device or the portal crane slewing mechanism 600 includes a computer device. The computer device includes a processor, a memory and a network interface connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data. The network interface of the computer device is used to communicate with other external terminals or servers through a network connection. In some embodiments, the network interface can be a wired network interface, and in some embodiments, the network interface can also be a wireless network interface. When the computer program is executed by the processor, the method in the embodiment of the present application is implemented.

[0121] Those skilled in the art will understand that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0122] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0123] As used in the above embodiments, the term "when..." may be interpreted to mean "if..." or "after..." or "in response to determining..." or "in response to detecting...", depending on the context. Similarly, the phrases "upon determining..." or "if (the stated condition or event) is detected" may be interpreted to mean "if determining..." or "in response to determining..." or "upon detecting (the stated condition or event)" or "in response to detecting (the stated condition or event)", depending on the context.

[0124] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media integration. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk), etc.

[0125] Those skilled in the art can understand that to implement all or part of the processes in the above-mentioned embodiments, the processes can be completed by computer programs to instruct related hardware, and the programs can be stored in computer-readable storage media. When the programs are executed, they can include the processes of the above-mentioned method embodiments. The aforementioned storage media include: ROM or random access memory RAM, magnetic disk or optical disk and other media that can store program codes.

Claims

1. A master-slave control method for a slewing mechanism motor of a portal crane, characterized in that: include: The programmable logic controller sends a first instruction to the first inverter; the first instruction includes a preset speed and a preset direction; The first motor feedback state parameters include the actual speed, actual torque, actual current, and actual running direction of the first rotary motor; When the programmable logic controller confirms that the first rotary inverter drives the first rotary motor to operate according to the first instruction, the programmable logic controller reads the first motor feedback state parameter of the first rotary inverter; The programmable logic controller calculates an error between the first motor feedback state parameter and the first instruction; The programmable logic controller determines whether the error is greater than an error threshold; If it is greater than the error threshold, the programmable logic controller calculates the change in the control error; The calculation function of the change in control error is: Δu=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2)]wherein, Δu is the change in the control error, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient, e(k) is the error, e(k-1) is the error of the previous control, and e(k-2) is the error of the previous two controls; The programmable logic controller applies the change of the control error to the first instruction to obtain a corrected first instruction; The programmable logic controller performs smoothing processing on the corrected first instruction to obtain a smoothed first instruction; The calculation function of the smoothing process is: Smoothed first instruction = α * modified first instruction + (1-α) * first instruction In the formula, α is the smoothing coefficient, 0<α<1; The programmable logic controller sends the smoothed first instruction to the first inverter; The programmable logic controller sends the first motor feedback state parameter as a second instruction to the second inverter; The programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction.

2. The method according to claim 1, characterized in that After the programmable logic controller confirms that the second rotary frequency converter drives the second rotary motor to operate according to the second instruction, the method further includes: When the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, the programmable logic controller reads the second motor feedback state parameter of the second rotary inverter; The programmable logic controller calculates a synchronization error according to the first motor feedback state parameter and the second motor feedback state parameter; The calculation function for calculating the synchronization error is: εs=(P1-P2)-(R1-R2) Wherein, εs is the synchronization error, P1 is the first motor feedback state parameter, P2 is the second motor feedback state parameter, R1 is the first instruction, and R2 is the second instruction; When the synchronization error exceeds a preset synchronization threshold, the programmable logic controller compensates the control output of the second inverter: The calculation function of compensation is: R2 ， =R2+Kc×εs In the formula, R2 ， is the second instruction after compensation, R2 is the second instruction, Kc is the compensation gain coefficient, and εs is the synchronization error; as the absolute value of the synchronization error increases, the compensation gain coefficient increases, and as the absolute value of the synchronization error decreases, the compensation gain coefficient decreases.

3. The method according to claim 1, characterized in that After the programmable logic controller confirms that the second rotary frequency converter drives the second rotary motor to operate according to the second instruction, the method further includes: When the programmable logic controller confirms that the second rotary inverter drives the second rotary motor to operate according to the second instruction, the programmable logic controller reads the second motor feedback state parameter of the second rotary inverter; The programmable logic controller calculates whether a difference between the first motor feedback state parameter and the second motor feedback state parameter is greater than an error threshold; If it is greater than the error threshold, the programmable logic controller sends the second motor feedback state parameter as a third instruction to the first inverter; The programmable logic controller confirms that the first rotary inverter drives the first rotary motor to operate according to the third instruction.

4. A portal crane slewing mechanism, characterized in that: The gantry crane slewing mechanism includes: one or more processors and a memory; the memory is coupled to the one or more processors, the memory is used to store computer program code, the computer program code includes computer instructions, and the one or more processors call the computer instructions to enable the gantry crane slewing mechanism to execute the method described in any one of claims 1-3.

5. A computer program product comprising instructions, characterized in that When the computer program product runs on a portal crane slewing mechanism, the portal crane slewing mechanism is enabled to execute the method according to any one of claims 1 to 3.

6. A computer-readable storage medium comprising instructions, characterized in that: When the instruction is executed on the portal crane slewing mechanism, the portal crane slewing mechanism is caused to execute the method according to any one of claims 1 to 3.

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