Overhead travelling crane and overhead travelling crane system

Abstract

The application discloses a crown block and a crown block system, wherein the crown block comprises a walking mechanism and a control device, the walking mechanism comprises a plurality of walking power sources connected with the control device, the control device determines the driving force of each walking power source according to the total driving force required by the walking mechanism in each control period and the power distribution variable corresponding to each walking power source determined periodically. The application adjusts the driving demand distribution relationship according to the load utilization rate difference of each walking power source. When the load utilization rate of a certain walking power source is too high, the control device reduces the equivalent driving component borne by the walking power source and transfers part of the driving demand to other walking power sources with lower load utilization rates, thereby avoiding that a certain walking power source is in a high load state for a long time. Moreover, the distribution relationship between the plurality of walking power sources is adjusted under the premise that the total driving force demand of the crown block is unchanged, so that the load utilization rate balanced control can be realized without affecting the original operation task of the crown block.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing equipment, and in particular to overhead cranes and overhead crane systems. Background Technology

[0002] Overhead cranes (OHTs) are key equipment in semiconductor FAB factories used for handling materials such as wafer cassettes. The overhead cranes move along overhead tracks via a traveling mechanism.

[0003] As shown in the patent document with application publication number CN116161549A, the existing overhead crane's traveling mechanism is usually equipped with multiple (2, 4, etc.) traveling power sources to provide the driving force required for the crane to move.

[0004] In theory, multiple power sources should work together to share the driving load during the operation of the overhead crane.

[0005] However, in actual operation, due to differences in crane structure, track geometry, wheel-rail contact state, load transfer, transmission efficiency, and response characteristics of each travel power source, uneven load distribution can easily occur among multiple travel power sources. Even if the overall speed or position of the crane meets the operating requirements, some travel power sources may remain under high load for extended periods, while the load utilization rate of other travel power sources is relatively low.

[0006] Existing overhead crane drive control systems typically focus more on the overall motion objectives of the crane, such as speed tracking, position tracking, or stopping accuracy, while neglecting to balance the load utilization among multiple travel power sources. When the drive force is distributed in a fixed ratio, it is difficult to dynamically adjust according to the actual load status of each travel power source, thus failing to effectively prevent the problem of long-term high-load operation of a single travel power source. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide an overhead crane and an overhead crane system.

[0008] The objective of this invention is achieved through the following technical solution: The overhead crane includes a traveling mechanism and a control device. The traveling mechanism includes multiple traveling power sources connected to the control device. In each control cycle, the control device determines the driving force of each traveling power source based on the total driving force required by the traveling mechanism and the power distribution variable corresponding to each traveling power source. The power allocation variable corresponding to each of the walking power sources is updated periodically according to the following formula: λ i,k =sat[λ i,k-1 -K λ ×(ρ i,k -ρavg,k )]; Where, λ i,k λ represents the power allocation variable corresponding to the i-th walking power source determined in the k-th update cycle; i，k-1 K represents the power allocation variable corresponding to the i-th walking power source determined in the (k-1)-th update cycle; λ ρ represents the load balancing adjustment coefficient. i，k ρ represents the load utilization rate of the i-th walking power source determined in the k-th update cycle. avg,k represents the average load utilization rate of all walking power sources determined in the k-th update cycle, and sat[] represents the limiting function.

[0009] Preferably, the total driving force required by the walking mechanism is periodically updated according to the following formula: ; Among them: U 0，m The total driving force required by the walking mechanism for the m-th control cycle; M eq The equivalent mass of the overhead crane or the overhead crane and the goods it transports; The target position, target velocity, and target acceleration are given by the upper-level trajectory planning module for the m-th control cycle, respectively. x m ,v m The actual position and speed of the overhead crane are shown in the following order. K p ,K v The position and velocity feedback coefficients are listed in order. This is an estimated value of the operating resistance during the m-th control cycle.

[0010] Preferably, in each update cycle, the control device determines the load sharing balance score according to the following formula and determines whether to update the power distribution variable corresponding to each walking power source based on the load sharing balance score; ; Among them, E ρk The load balancing score is given for the k-th update cycle; N represents the number of power sources for walking; When the determined load sharing balance score is greater than or equal to the score threshold, the load sharing imbalance is determined, and the power allocation variable corresponding to each walking power source is updated. When the determined load sharing balance score is less than the score threshold, the load sharing balance is determined, and the power allocation variable corresponding to each walking power source is not updated.

[0011] Preferably, when determining the power distribution variable corresponding to a walking power source, the power distribution variable is restricted according to the following formula: |λ i,k -λ i,k-1 |≤△λ max ; △λ max This represents the maximum allowable change of the dynamic allocation variable between two adjacent update cycles.

[0012] Preferably, when the absolute value of the difference between the load utilization rate and the safety protection value of a walking power source reaches a second threshold, the control device limits the driving force of the walking power source from continuing to increase.

[0013] Preferably, in each control cycle, the control device determines the driving force of each walking power source according to the following formula: ; Among them, U i，m This represents the driving force of the i-th walking power source determined in the m-th control cycle; U 0，m The total driving force determined for the m-th control cycle; λ i，m，norm This represents the normalized value of the power allocation variable corresponding to the i-th travel power source in the m-th control cycle.

[0014] The overhead crane includes a traveling mechanism and a control device. The traveling mechanism includes two traveling power sources connected to the control device. In each control cycle, the control device determines the driving force of each traveling power source based on the total driving force required by the traveling mechanism and the power distribution variable corresponding to each traveling power source. The power allocation variable is updated periodically according to the following formula: λ k =sat[λ k-1 -K λ ×e ρk ]; Where, λ k λ represents the dynamic allocation variable for the k-th update cycle. k-1 K represents the dynamic allocation variable in the (k-1)th update cycle; λ Indicates the load balancing adjustment coefficient; e ρk represents the difference in load utilization between the first and second walking power sources determined in the k-th update cycle, and sat[] represents the limiting function.

[0015] Preferably, in each update cycle, the control device first determines the e ρkIf the absolute value is greater than or equal to the first threshold, then update the power allocation variable; If not, the dynamic allocation variable will not be updated.

[0016] Preferably, the control device determines the driving force of the two walking power sources according to the following formula: U 1m =λ m ×U 0，m ; U 2m =[1-λ m ]×U 0，m ; Among them, U 1m λ represents the driving force of the first walking power source during the m-th control cycle. m U is the power allocation variable corresponding to the m-th control cycle. 0,m The total driving force determined for the m-th control cycle; U 2m For the m-th control cycle, the driving force of the second walking power source.

[0017] The overhead crane system includes any of the overhead cranes described above.

[0018] The advantages of the technical solution of this invention are mainly reflected in: First, it can reduce the risk of a single walking power source operating under high load for a long time.

[0019] This invention adjusts the drive demand allocation relationship based on the difference in load utilization rates of each driving power source. When the load utilization rate of a certain driving power source is too high, the control device reduces the equivalent drive component it bears and transfers some drive demand to other driving power sources with lower load utilization rates, thereby preventing a certain driving power source from being in a high-load state for a long time.

[0020] Second, it can improve the consistency of load sharing among multiple walking power sources.

[0021] This invention calculates the difference in load utilization and dynamically adjusts the control power distribution variables based on this difference, gradually bringing the load utilization rates of multiple travel power sources closer together. Compared to a fixed distribution method, this invention can adaptively adjust according to the actual operating conditions, making it more suitable for situations with differences in travel power source performance, transmission efficiency, or wheel-rail contact conditions.

[0022] Third, it can improve the reliability of aerial transport vehicle operation.

[0023] When the load utilization rate of a certain walking power source approaches a preset protection threshold, this invention can limit the control command of that walking power source from increasing further and transfer the allocable drive demand to other walking power sources with load margins. In this way, the probability of a single walking power source approaching an overload state can be reduced, improving the reliability of continuous system operation.

[0024] Fourth, it can improve the drive distribution state without changing the overall motion target of the crane.

[0025] This invention does not change the target speed, target position, braking requirements, or restart requirements of the aerial transport vehicle. Instead, it adjusts the distribution relationship among multiple travel power sources while keeping the total driving force requirement of the crane constant. Therefore, this invention can achieve balanced load utilization control without affecting the original operation of the crane.

[0026] Fifth, it can improve the stability of the control process.

[0027] This invention sets a dead zone threshold, amplitude limit constraint, and rate of change limit during the adjustment of the control power distribution variable. The dead zone threshold prevents frequent adjustments to the control power distribution variable caused by small fluctuations in load utilization; the amplitude limit constraint and rate of change limit prevent sudden changes in the control power distribution variable from causing impacts, vibrations, or sudden changes in the load of the traveling power source. Therefore, this invention enables a smoother load balancing adjustment process.

[0028] Sixth, it has good engineering applicability.

[0029] The load characterization parameters used in this invention can be obtained from at least one of the following: driver load rate, motor current, output torque, output power, and wheel-end traction force, without relying on a single type of sensor or a single control mode. Control commands can also be converted into torque commands, speed commands, current commands, or position compensation commands depending on the specific system. Therefore, this invention is applicable to various types of multi-drive aerial transport vehicle control devices. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process by which the control device of the present invention controls the driving force of each walking power source; Figure 2 This is a flowchart of the control device of the present invention periodically updating the power distribution variables corresponding to each walking power source; Figure 3 This is a detailed flowchart of the control device of the present invention performing periodic updates of the power distribution variables corresponding to each walking power source; Figure 4 This is a graph showing the change in load utilization of the two walking power sources when the control method of the present invention is used to control the two walking power sources. Figure 5 This is a graph showing the change in load utilization of the two driving power sources when the driving force of the two driving power sources is distributed according to a fixed ratio. Detailed Implementation

[0031] The objectives, advantages, and features of this invention will be illustrated and explained through the following non-limiting description of preferred embodiments. These embodiments are merely typical examples of applying the technical solutions of this invention, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by this invention.

[0032] In the description of the solution, it should be noted that the terms "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] Example 1 The overhead crane disclosed in this invention will be described below with reference to the accompanying drawings. Like existing overhead cranes, it includes a traveling mechanism and a control device. The traveling mechanism includes multiple traveling power sources connected to the control device. These power sources are known and feasible motors. The number of power sources can be designed as needed, such as two or four, and is not limited here. When there are two power sources, each power source drives a pair of traveling wheels; when there are four power sources, each power source can drive one traveling wheel. The control device can be a known and feasible control device, such as a PLC or a PCB control board integrating a microcontroller, communication module, power supply circuit, drive circuit, and other functional modules, and is not limited here. The overhead crane also includes other known overhead crane structures, such as a main frame driven by the traveling mechanism, and lifting mechanisms and gripping mechanisms mounted on the main frame, which will not be elaborated here.

[0034] As attached Figure 1As shown, the control device determines the driving force of each walking power source according to a set control cycle. This set control cycle can be customized as needed; for example, it can be between 1 and 5 milliseconds. A shorter control cycle facilitates timely detection of control errors and rapid response. Simultaneously, this set control cycle also considers the system's computing power and communication stability. In each control cycle, the control device determines the driving force of each walking power source based on the total driving force required by the walking mechanism and the determined power distribution variables corresponding to each walking power source. The method for determining the driving force of each walking power source will be explained in detail below and will not be elaborated upon here.

[0035] In each control cycle, the control device needs to first determine the total driving force required by the traveling mechanism. The total driving force required by the traveling mechanism can be determined based on the target speed, target position, and target acceleration to be achieved in the current control cycle. This total driving force can be understood as the total traction force required for the vehicle's current operation.

[0036] The total driving force required by the walking mechanism can be calculated using the following formula: ; Among them: U 0，m The total driving force required by the walking mechanism for the m-th control cycle; M eq For the equivalent mass of the overhead crane or the overhead crane and the cargo, when the overhead crane is not carrying a load, M eq Equal to the weight of the overhead crane itself; when the overhead crane is moving goods, M eq The effective mass M is the sum of the crane's own mass and the load mass of the goods it is currently handling. The crane's own mass can be predetermined and stored in the control device at the time of manufacture through weighing or other methods. The load mass corresponding to different types of goods can be measured and stored in the control device in advance. The control device determines the corresponding load mass based on the type of goods included in the handling task, and then determines the equivalent mass M corresponding to the current handling task. eq .

[0037] The target position, target velocity, and target acceleration are given by the upper-level trajectory planning module for the m-th control cycle, respectively. x m ,v m The actual position and speed of the overhead crane are shown in the following order. K p ,K v The position and speed feedback coefficients, in order, can be predetermined and stored in the memory of the control device for later retrieval. The estimated running resistance for the m-th control cycle is determined based on the type of track section the crane is currently on and its position within that section, taking into account the differences in wheel-rail action and mechanical resistance experienced by the crane at different locations on different types of tracks and within the same track section.

[0038] Specifically, for different types of tracks, the corresponding position-running resistance relationship can be pre-calibrated through overhead crane operation tests and stored in the memory of the control device. For example, corresponding position-running resistance relationships can be established for different types of tracks such as straight tracks, 90° curved tracks, and 180° curved tracks. For similar tracks with the same or similar structural parameters, the same position-running resistance relationship can be used.

[0039] The estimated operating resistance value for the m-th control cycle can be determined using the following formula: ; in, This is the estimated operating resistance value for the m-th control cycle; c indicates the track type of the current track section of the crane, such as straight track, 90° curved track, 180° curved track, etc. This indicates the position of the crane in the current track segment during the m-th control cycle. The position can be represented by the running distance relative to the entrance of the current track segment, the path position along the track direction, or other parameters that characterize the crane's position within the current track segment. The specific method for determining the crane's position in the current track segment is a well-known technique, such as using a combination of encoder and absolute position detection on the track. This is not innovative and will not be elaborated upon here. This represents the pre-defined position-running resistance relationship corresponding to track type c, used to describe the estimated running resistance of the crane at different positions on that type of track.

[0040] The position-running resistance relationship can be obtained through pre-running calibration. For example, the crane is traversed under preset operating conditions through a track section of the type to be calibrated, at multiple positions within the track section. The output torque of each travel power source is obtained, and the running resistance at the corresponding position is determined based on the traction force generated by each travel power source and the acceleration of the crane along the track running direction. ; in, Indicates position Estimated operating resistance at the location; N represents the number of power sources for walking; Indicates the location of the overhead crane. At that time, the traction force generated by the i-th walking power source; Indicates the location of the overhead crane. At that time, the tangential acceleration along the direction of track movement.

[0041] The traction force generated by the i-th power source can be determined based on its output torque: ; in, Indicates the location of the overhead crane. At that time, the output torque of the i-th walking power source; This represents the transmission ratio between the i-th power source and the corresponding wheel. This represents the transmission efficiency between the i-th power source and the corresponding wheel. This represents the radius of the wheel corresponding to the i-th power source for walking.

[0042] Preferably, when calibrating the position-running resistance relationship, the overhead crane can pass through the track section to be calibrated at a basically constant speed. At this time, the tangential acceleration of the overhead crane along the track running direction is close to zero, that is: ; Therefore, the running resistance at the corresponding location can be approximately determined as: ; By determining the estimated running resistance at different locations on the same type of track, multiple location-running resistance data points can be obtained, for example: ; The control device can store the above-mentioned multiple position-running resistance data points in the form of a data table, lookup table, or fitted curve, thereby establishing the position-running resistance relationship corresponding to this type of track. When the actual position is between two adjacent pre-calibrated positions, interpolation can be performed based on the estimated operating resistance values ​​corresponding to the adjacent positions to obtain the estimated operating resistance value corresponding to the current position.

[0043] During the actual operation of the overhead crane, the control device first determines the track type (c) of the current track section where the crane is located based on the current transport path or track map; then, based on information from encoders, gyroscopes, inertial measurement units, or other position detection devices, it determines the crane's position within the current track section. Then, the position-running resistance relationship corresponding to track type c is invoked. According to the current location Determine the estimated operating resistance value for the m-th control cycle. .

[0044] Therefore, for track sections such as curved tracks where the running resistance changes significantly with the track position, it is not necessary to use a single fixed running resistance estimate. Instead, the corresponding running resistance estimate can be obtained based on the actual position of the crane in the track section. This allows the determination of the total driving force to take into account the resistance changes at different track types and different positions in the same track section.

[0045] When the total driving force required by the traveling mechanism is determined in each control cycle, the control device can read the power allocation variables corresponding to each traveling power source and calculate the driving force of each traveling power source. Based on the driving force of each traveling power source determined in each control cycle, the control device can control the operation of each traveling power source. From the start of controlling the crane movement until the control device first updates and obtains the power allocation variables corresponding to each traveling power source, the control device can determine the driving force of each traveling power source based on the preset power allocation variables for each traveling power source.

[0046] As attached Figure 2 As shown, the control device updates the power distribution variable corresponding to each walking power source according to the set update cycle. The update cycle can be the same as or different from the control cycle. In a preferred embodiment, the update cycle is a positive integer multiple of the control cycle. For example, the update cycle is preferably 5-10 times the control cycle. Making the update cycle a positive integer multiple of the control cycle can effectively avoid additional vibration caused by rapidly adjusting the power distribution variable.

[0047] Within each update cycle, the control device can sample the load characterization parameters of each walking power source multiple times and determine the load utilization rate of each walking power source based on the load characterization parameters collected within each update cycle. The load characterization parameters are, for example, driver load rate, motor current, output torque, output power, etc. Of course, the load characterization parameters can also be wheel end traction force determined based on the collected output torque, etc. In this embodiment, the load characterization parameters of each power source are not specifically limited.

[0048] When determining the load utilization rate of each of the walking power sources using only one load characterization parameter, the control device can determine the load utilization rate of each of the walking power sources according to the following formula: ρ i，k =|L i,k | / L i,max ; Where, ρ i，k The load utilization rate of the i-th walking power source determined for the k-th update cycle; L i,kThis refers to the load data of the i-th walking power source within the k-th update cycle. The load data is the mean, median, peak, or root mean square (RMS) of a selected load characterization parameter of the i-th walking power source collected within the k-th update cycle; no specific limitation is specified here. i,max The maximum allowable value of the load characterization parameter for the i-th walking power source.

[0049] For example, when the driver load rate is used as a load characterization parameter, L i,k L represents the mean, median, peak, or root mean square load rate of the driver of the i-th walking power source within the k-th update cycle. i,max The maximum allowable load rate for the driver of the i-th walking power source.

[0050] When using multiple load characterization parameters to determine the load utilization rate of the walking power source, each load characterization parameter can be normalized first, and then the normalized results can be weighted and fused.

[0051] Specifically, the normalized load utilization rate ρ corresponding to the q-th load characterization parameter of the i-th walking power source in the m-th update cycle can be determined according to the following formula. i,q,m : ρ i,q,k =|L i,q,k | / L i,q,max ; Where: L i,q,k For the m-th update cycle, the q-th load characterization parameter of the i-th walking power source, L i,q,max For the m-th update cycle, the maximum allowable value corresponding to the q-th load characterization parameter of the i-th walking power source; This means that different load characterization parameters are normalized using their corresponding maximum allowable values. For example, the motor current is normalized using the maximum allowable current corresponding to the motor current, the output torque is normalized using the maximum allowable torque corresponding to the output torque, the output power is normalized using the maximum allowable output power corresponding to the output power, and the driver load rate is normalized using the maximum allowable value (100%) corresponding to the driver load rate, etc.

[0052] Then, the load utilization rate ρ of the i-th walking power source in the m-th update cycle can be determined according to the following formula. i,k : ; Among them, w q w represents the weight corresponding to the q-th load characterization parameter. q It is greater than or equal to 0, and the sum of all weights is 1; M is the number of load characterization parameters.

[0053] After determining the load utilization rate of each walking power source, the average load utilization rate of all walking power sources can be further determined.

[0054] Subsequently, the control device determines a power distribution variable corresponding to the walking power source in each update cycle according to the following formula: λ i,k =sat[λ i,k-1 -K λ ×(ρ i,k -ρ avg,k )]; Where, λ i,k Let λ represent the power allocation variable corresponding to the i-th walking power source determined in the k-th update cycle (the current update cycle). i，k The value range is limited to the set minimum allocation coefficient and maximum allocation coefficient, which is used to avoid a certain driving power source bearing too little or too much driving force. The minimum allocation coefficient and maximum allocation coefficient can be customized as needed, and are not limited here.

[0055] λ i，k-1 λ represents the power allocation variable corresponding to the i-th walking power source determined in the (k-1)-th update cycle (the previous update cycle); in the first update cycle, λ i，k-1 The power allocation variable can be preset for the i-th walking power source.

[0056] K λ This represents the load balancing adjustment factor (which can be customized as needed; no specific limit is specified here); ρ i，k ρ represents the load utilization rate of the i-th walking power source determined in the k-th update cycle. avg,k represents the average load utilization rate of all walking power sources determined in the k-th update cycle, and sat[] represents the limiting function.

[0057] After determining the power allocation variable corresponding to each walking power source, the power allocation variable corresponding to each walking power source can be normalized according to the following formula to obtain the normalized value of the power allocation variable corresponding to each walking power source. ; ; Where, λ i，k，norm The normalized value of the power allocation variable corresponding to the i-th walking power source determined in the k-th update cycle; N is the number of walking power sources.

[0058] That is, divide the load utilization rate of each walking power source by the sum of the load utilization rates of all walking power sources.

[0059] Subsequently, the driving force of each walking power source can be calculated based on the normalized value of the power allocation variable corresponding to each walking power source determined in each update cycle.

[0060] In each control cycle, the control device determines the driving force of each walking power source according to the following formula: ; Among them, U i，m This represents the driving force of the i-th walking power source determined in the m-th control cycle; U 0，m The total driving force required for the traveling mechanism, as determined in the m-th control cycle; λ i，m，norm This represents the normalized value of the power allocation variable corresponding to the i-th travel power source in the m-th control cycle.

[0061] Because the control cycle and update cycle are different, after the power allocation variables corresponding to each travel power source are determined in the k-th update cycle, and before the power allocation variables corresponding to each travel power source are updated again in the (k+1)-th update cycle, the control device determines the normalized value and U of the power allocation variables corresponding to each travel power source according to the power allocation variables corresponding to each travel power source determined in the k-th update cycle during multiple control cycles during this period. i，k For example, after the power allocation variables corresponding to each walking power source are determined in the first update cycle, during the period from the determination of the power allocation variables corresponding to each walking power source in the second update cycle, when the control device determines the driving force of each walking power source in each control cycle, it calculates the normalized value of the power allocation variable corresponding to each walking power source based on the power allocation variables corresponding to each walking power source determined in the first update cycle.

[0062] As attached Figure 3 As shown, when the control device determines the power distribution variable in each update cycle, it first determines the load sharing balance score according to the following formula; ; Among them, E ρk The load balancing score for the k-th update cycle; N is the number of power sources for movement; The load sharing and balancing score is used to determine the load balance among multiple walking power sources. When E ρk A large value indicates a significant difference in load utilization between different travel power sources, necessitating a readjustment of the load conditions for each travel power source; when E ρk When the value is relatively small, it indicates that the load distribution among multiple power sources for movement is relatively balanced.

[0063] Therefore, the control device can determine whether the load sharing balance score has reached the set score threshold (which can be customized as needed, and is not limited here) to determine whether the power distribution variables corresponding to each walking power source need to be updated.

[0064] When the determined load sharing balance score is greater than or equal to the score threshold, the load sharing imbalance is determined, and the power allocation variable corresponding to each walking power source is updated. When the determined load sharing balance score is less than the score threshold, the load sharing balance is determined, and the power allocation variables corresponding to each walking power source are not updated. That is, the driving force of each walking power source is still determined according to the power allocation variables determined in the previous update cycle.

[0065] Furthermore, when determining the power allocation variables, the power allocation variables are constrained according to the following formula: |λ i , k -λ i , k-1 |≤△λ max ; △λ max This represents the maximum allowable change of the dynamic allocation variable determined in adjacent update cycles.

[0066] That is, determine λ in the current update cycle. i , k Then, the λ value determined in the current update cycle is further determined. i , k λ determined relative to the previous update cycle k-1 Does the change range exceed the set range requirement? If it does, then the determined λ... i , k Apply restrictions to make the restricted λ i , k With λ k-1 The absolute value of the difference is equal to Δλ max For example, λ i , k =0.6, λ i , k-1 =0.4, Δλ max =0.15, |0.6-0.4|=0.2>0.15, then λ i , k With the value limited to 0.55, then |0.55 - 0.4| = 0.15 = Δλ max For example, λ i , k =0.3, λ i , k-1 =0.5, |0.3-0.5|=0.2>0.15, then λi , k With the value limited to 0.35, then |0.35 - 0.5| = 0.15 = Δλ max .

[0067] Furthermore, when the absolute value of the difference between the load utilization rate and the safety protection value of a walking power source reaches a second threshold (which can be pre-defined as needed and is not limited here), the control device restricts the driving force of the walking power source from continuing to increase. The safety protection value is used to characterize the upper limit of the load utilization rate that the walking power source is allowed to reach, and can be pre-defined according to the actual working conditions, and is not limited here. Specifically, when the latest determined load utilization rate of a walking power source is close to the set safety protection value, if the driving force of the walking power source determined in the current control cycle is greater than or equal to the driving force of the walking power source determined in the previous control cycle, the driving force of the walking power source is limited to the driving force of the walking power source determined in the previous cycle (i.e., the driving force of the walking power source remains unchanged), and the incremental part of the driving force of the walking power source determined in the current control cycle exceeding the driving force of the walking power source determined in the previous control cycle is transferred to one or more of the four walking power sources with the latest determined load utilization rates, where the load utilization rate is relatively low. The incremental portion can be allocated to multiple walking power sources with relatively low load utilization rates according to the calculated allocation ratio. The allocation ratio can be determined using known methods, such as calculating it based on the load utilization margin of the walking power sources with relatively low load utilization rates. This is not limited here. Therefore, the allocation ratio of walking power sources with lower load utilization rates (larger load utilization margins) is larger.

[0068] If the driving force of the walking power source determined in the current control cycle is less than the driving force of the walking power source determined in the previous cycle, then the walking power source is controlled to work according to the driving force of the walking power source determined in the current control cycle.

[0069] When the difference between the load utilization rate of the walking power source and the safety protection value decreases to less than the second threshold or the third threshold (the third threshold is less than the second threshold, and can be customized as needed, without limitation here), the walking power source is controlled to work again based on the driving force of the walking power source determined in real time.

[0070] Example 2 This embodiment discloses an overhead crane, which also includes a traveling mechanism and a control device. The traveling mechanism includes two traveling power sources connected to the control device. The control device also determines the driving force of the two traveling power sources based on the total driving force required by the traveling mechanism determined in each control cycle and the acquired power distribution variables. The difference from Embodiment 1 above is that the power allocation variable is determined according to the following formula: λ k =sat[λ k-1 -K λ ×e ρk ]; Where, λ k λ represents the dynamic allocation variable for the k-th update cycle. k The value range of λ is limited to between the set minimum and maximum allocation coefficients to prevent a single driving power source from bearing too little or too much driving force demand; k-1 K represents the dynamic allocation variable in the (k-1)th update cycle; λ Indicates the load balancing adjustment coefficient; e ρk e represents the difference in load utilization between the first and second travel power sources determined in the k-th update cycle. ρk That is, e ρk =ρ 1k -ρ 2k , ρ 1k ρ is the load utilization rate of the first walking power source determined in the k-th update cycle. 2k The load utilization rate of the second walking power source is determined for the kth update cycle; sat[] represents the limiting function.

[0071] At this time, the control device determines the driving force of the two walking power sources according to the following formula: U 1m =λ m ×U 0，m ; U 2m =[1-λ m ]×U 0，m ; Among them, U 1m λ represents the driving force of the first walking power source during the m-th control cycle. m U is the power allocation variable corresponding to the m-th control cycle. 0,m The total driving force determined for the m-th control cycle; U 2m For the m-th control cycle, the driving force of the second walking power source.

[0072] Furthermore, in each update cycle, the control device first determines the e ρk Is the absolute value greater than or equal to the first threshold ρ? 阈 (This can be customized as needed, and is not limited here.) If not, it means that the load utilization rate of the two walking power sources is small. The power allocation variable will not be updated, and the driving force of the two walking power sources will continue to be determined according to the power allocation variable determined in the previous update cycle. If so, then update the power allocation variable according to the above formula.

[0073] When e ρk Greater than or equal to ρ 阈 This indicates that the load utilization rate of the first walking power source is significantly higher than that of the second walking power source. At this time, the control device reduces the power distribution variable, thereby reducing the driving force borne by the first walking power source and increasing the driving force borne by the second walking power source.

[0074] When e ρk Less than or equal to -ρ 阈 This indicates that the load utilization rate of the second walking power source is significantly higher than that of the first walking power source. At this time, the control device increases the power distribution variable, increasing the driving force borne by the first walking power source while decreasing the driving force borne by the second walking power source.

[0075] In this embodiment, the control device is the same as in Embodiment 1 above, which determines the load utilization rate of each walking power source, limits the power distribution variables, and sets safety limits for the load utilization rate, etc., which will not be elaborated here.

[0076] Appendix Figure 4 This diagram illustrates, in a simulation example, the load utilization curves of two walking power sources with different maximum load capacities, obtained by controlling the two walking power sources using the control method of this invention. (Attached) Figure 5 The diagram shows the load utilization curves of the two walking power sources controlled by a fixed allocation method. Figure 4 and attached Figure 5 The comparison shows that when the control device controls the two walking power sources to work according to the control method of the present invention, the difference in load utilization between the two walking power sources is significantly smaller. This indicates that the control method of the present invention can effectively adjust the distribution relationship of the total driving force according to the load data status of the walking power sources, making the load utilization of multiple walking power sources closer and avoiding long-term high-load operation of a single walking power source.

[0077] Example 3 This embodiment discloses a crane system, including the crane described in the above embodiment.

[0078] This invention has many other embodiments, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of this invention.

Claims

1. An overhead crane, comprising a traveling mechanism and a control device, wherein the traveling mechanism includes multiple traveling power sources connected to the control device, characterized in that: The control device determines the driving force of each walking power source in each control cycle based on the total driving force required by the walking mechanism and the power distribution variable corresponding to each walking power source. The power allocation variable corresponding to each of the walking power sources is updated periodically according to the following formula: l i,k =sat[λ i,k-1 -K λ ×(p i,k -r avg,k )]; Where, λ i,k λ represents the power allocation variable corresponding to the i-th walking power source determined in the k-th update cycle; i，k-1 K represents the power allocation variable corresponding to the i-th walking power source determined in the (k-1)-th update cycle; λ ρ represents the load balancing adjustment coefficient. i，k ρ represents the load utilization rate of the i-th walking power source determined in the k-th update cycle. avg,k represents the average load utilization rate of all walking power sources determined in the k-th update cycle, and sat[] represents the limiting function.

2. The overhead crane according to claim 1, characterized in that: The total driving force required by the walking mechanism is updated periodically according to the following formula: ； Among them: U 0，m The total driving force required by the walking mechanism for the m-th control cycle; M eq The equivalent mass of the overhead crane or the overhead crane and the goods it transports; The target position, target velocity, and target acceleration are given by the upper-level trajectory planning module for the m-th control cycle, respectively. x m ,v m The actual position and speed of the overhead crane are shown in the following order. K p ,K v The position and velocity feedback coefficients are listed in order. This is an estimated value of the operating resistance during the m-th control cycle.

3. The overhead crane according to claim 1, characterized in that: In each update cycle, the control device determines the load sharing balance score according to the following formula and determines whether to update the power distribution variable corresponding to each walking power source based on the load sharing balance score. ； Among them, E ρk The load balancing score is given for the k-th update cycle; N represents the number of power sources for walking; When the determined load sharing balance score is greater than or equal to the score threshold, the load sharing imbalance is determined, and the power allocation variable corresponding to each walking power source is updated. When the determined load sharing balance score is less than the score threshold, the load sharing balance is determined, and the power allocation variable corresponding to each walking power source is not updated.

4. The overhead crane according to claim 1, characterized in that: When determining the power distribution variable corresponding to a walking power source, the power distribution variable is constrained according to the following formula: |l i,k -l i,k-1 |≤△λ max ; △λ max This represents the maximum allowable change of the dynamic allocation variable between two adjacent update cycles.

5. The overhead crane according to claim 1, characterized in that: When the absolute value of the difference between the load utilization rate and the safety protection value of a walking power source reaches a second threshold, the control device restricts the driving force of the walking power source from continuing to increase.

6. The overhead crane according to any one of claims 1-5, characterized in that: In each control cycle, the control device determines the driving force of each walking power source according to the following formula: ； Among them, U i，m This represents the driving force of the i-th walking power source determined in the m-th control cycle; U 0，m The total driving force determined for the m-th control cycle; λ i，m，norm This represents the normalized value of the power allocation variable corresponding to the i-th travel power source in the m-th control cycle.

7. An overhead crane, comprising a traveling mechanism and a control device, wherein the traveling mechanism includes two traveling power sources connected to the control device, characterized in that: The control device determines the driving force of each walking power source in each control cycle based on the total driving force required by the walking mechanism and the power distribution variable corresponding to each walking power source. The power allocation variable is updated periodically according to the following formula: l k =sat[λ k-1 -K λ ×e ρk ]; Where, λ k λ represents the dynamic allocation variable for the k-th update cycle. k-1 K represents the dynamic allocation variable in the (k-1)th update cycle; λ Indicates the load balancing adjustment coefficient; e ρk represents the difference in load utilization between the first and second walking power sources determined in the k-th update cycle, and sat[] represents the limiting function.

8. The overhead crane according to claim 7, characterized in that: In each update cycle, the control device first determines the e ρk Is the absolute value greater than or equal to the first threshold? If so, then update the power allocation variable; If not, the dynamic allocation variable will not be updated.

9. The overhead crane according to claim 7, characterized in that: The control device determines the driving force of the two walking power sources according to the following formula: U 1m =λ m ×U 0，m ; U 2m =[1-λ m ]×U 0，m ; Among them, U 1m λ represents the driving force of the first walking power source during the m-th control cycle. m U is the power allocation variable corresponding to the m-th control cycle. 0,m The total driving force determined for the m-th control cycle; U 2m For the m-th control cycle, the driving force of the second walking power source.

10. A crane system, characterized in that: Including the overhead crane as described in any one of claims 1-9.

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