A crane double limiter detection system and method

Abstract

The present invention proposes a double limiter detection system for a crane, the system comprising: a double limiter module, an acquisition module, a signal transmission module and a controller module, wherein the acquisition module is electrically connected to the double limiter module, the acquisition module has four acquisition points, the first acquisition point is arranged at the input end of the double limiter module, the second acquisition point and the third acquisition point are arranged between the first-level limiter and the second-level limiter, and the fourth acquisition point is arranged at the output of the double limiter module for collecting the working voltage and current signals of the double limiter; the signal transmission module is communicatively connected to the acquisition module, the controller module is electrically connected to the signal transmission module, the collected signal is transmitted to the controller module for processing through the signal transmission module, the working status of the two limiters can be detected and judged, and comprehensive real-time monitoring of the working status of the double limiters of the crane is realized, safety hazards are prevented, and safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of crane detection, and in particular to a crane double limiter detection system and method. Background Art

[0002] With the rapid development of economy and society, the number of lifting machinery and equipment has increased rapidly, and the scale of use has also been expanding. Crane refers to a multi-action lifting machinery that vertically lifts and horizontally transports heavy objects within a certain range. Bridge cranes and gantry cranes are the most widely used. Bridge cranes refer to bridge cranes whose ends of the bridge are directly supported on elevated tracks through running devices. Gantry cranes refer to bridge cranes whose bridges are supported on ground tracks or foundations through legs on both sides. During the use of bridge and gantry cranes, accidents caused by improper configuration, missing, loss and failure of height limit devices account for a relatively high proportion.

[0003] The crane limiter is an essential safety device for bridge and gantry cranes. It is used to limit the rising height of the picking device. When the crane's hoist rises to the upper limit position, the limiter will automatically cut off the power supply to prevent the hook and other picking devices from continuing to rise, so as to avoid the crane hitting the top, causing the electric hoist or winch to continue working and break the wire rope, thereby causing heavy objects to fall. According to the latest "Notice of the General Office of the State Administration for Market Regulation on Carrying out the Investigation and Control of Hidden Dangers in Lifting Machinery", lifting machinery manufacturers should install two different forms of height limit devices on newly manufactured bridge and gantry cranes at the same time, such as any two of the heavy hammer type, fire-off type and pressure plate type height limit devices. For in-use bridge and gantry cranes, lifting machinery users should add a set of height limit devices different from the original configuration to the in-use bridge and gantry cranes to ensure that the equipment meets the requirements of double limit devices.

[0004] However, due to the different height conditions for triggering the double limiters, when the upper limiter is triggered, the lifting power supply will be cut off, causing the lifting mechanism to stop working and unable to continue to trigger the next limiter upward. This will result in the limiter performance test showing that when the first limiter is working normally, it will be impossible to test whether the second limiter can work normally. If the electrical system of the limiter is damaged, causing the limiter to fail, extreme situations such as topping out are very likely to occur, which may cause serious production accidents and reduce safety. Summary of the invention

[0005] In view of this, the present invention proposes a crane double limiter performance detection method, which can bypass the first-level limiter and directly detect the working performance of the second-level limiter to achieve independent control of the crane double limiter so that special equipment personnel can detect limiter failures to prevent safety hazards and improve safety.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a crane double limiter detection system, the system comprising: a double limiter module, a collection module, a signal transmission module and a controller module, wherein:

[0007] The acquisition module is electrically connected to the dual stopper module, and the acquisition module has four acquisition points, the first acquisition point is arranged at the input end of the dual stopper module, the second acquisition point and the third acquisition point are arranged between the first-level stopper and the second-level stopper, and the fourth acquisition point is arranged at the output of the dual stopper module, and is used to collect the working voltage and current signals of the dual stopper;

[0008] The signal transmission module is communicatively connected to the acquisition module, the controller module is electrically connected to the signal transmission module, and the acquired signal is transmitted to the controller module for processing via the signal transmission module.

[0009] On the basis of the above technical scheme, preferably, the dual limiter module includes a three-phase motor, an ascending relay KM1, a descending relay KM2, a fuse, a main switch SB1, an ascending switch SB2, a descending switch SB3, a first limit switch ZWK1, a second limit switch ZWK2, a low limit switch FWK, an ascending signal light ZHD, a descending signal light FHD and a thermal relay, wherein the ascending relay KM1 and the descending relay KM2 each have three contacts, the three-phase motor is electrically connected to the first contacts of the ascending relay KM1 and the descending relay KM2 and the fuse respectively, the other end of the first contacts of the ascending relay KM1 and the descending relay KM2 are commonly connected to the coil of the thermal relay, the other end of the coil of the thermal relay is electrically connected to the three-phase motor, the other end of the fuse is electrically connected to the main switch SB1, the other end of the main switch SB1 is electrically connected to the second contact of the ascending relay KM1, the second contact of the descending relay KM2, the ascending switch SB2 and the descending switch SB3 respectively, and the ascending switch S B2 and the other end of the second contact of the rising relay KM1 are commonly connected to the second limit switch ZWK2, the other end of the second limit switch ZWK2 is electrically connected to the first limit switch ZWK1, the other end of the first limit switch ZWK1 is electrically connected to the third contact of the falling relay KM2, the other end of the third contact of the falling relay KM2 is electrically connected to the coil of the rising relay KM1 and the rising signal light ZHD respectively, the falling switch SB3 and the other end of the second contact of the falling relay KM2 are commonly connected to the low limit switch FWK, the other end of the low limit switch FWK is electrically connected to the third contact of the rising relay KM1, the other end of the third contact of the rising relay KM1 is electrically connected to the coil of the falling relay KM2 and the falling signal light FHD respectively, the other end of the coil of the rising relay KM1 and the other end of the rising signal light ZHD and the other end of the coil of the falling relay KM2 and the other end of the falling signal light FHD are commonly connected to the contact of the thermal relay, and the other end of the contact of the thermal relay is electrically connected to the neutral line.

[0010] On the basis of the above technical scheme, preferably, the acquisition module is a wireless communication relay, the first acquisition point of the wireless communication relay is electrically connected to the other end of the main switch SB1, the second acquisition point of the wireless communication relay is electrically connected to the other end of the second limit switch ZWK2, the third acquisition point of the wireless communication relay is electrically connected to the other end of the first limit switch ZWK1, the fourth acquisition point of the wireless communication relay is electrically connected to the other end of the contact of the thermal relay, and a circuit breaker is also provided between the second acquisition point of the wireless communication relay and the third acquisition point of the wireless communication relay.

[0011] On the basis of the above technical solution, preferably, the signal transmission module includes a wireless collector and a radio station, the wireless collector communicates wirelessly with the collection module, the wireless collector and the radio station communicate signals through an RS485 interface, and the radio station is electrically connected to the controller module.

[0012] On the basis of the above technical solution, preferably, a display screen module is further included, the input end of the display screen module is electrically connected to the output end of the controller module, and is used to display the dual limiter status information detected by the output of the controller module.

[0013] In a second aspect, the present invention further provides a crane double stopper detection method, which is implemented by the crane double stopper detection system as described above, and the method comprises the following steps:

[0014] S1, the four collection points of the collection module are respectively set at the input end of the double limiter module, between the first-level limiter and the second-level limiter, and the output end of the double limiter module, and the voltage and current of each point are collected respectively, and the collected voltage and current signals are wirelessly transmitted to the signal transmission module, and the signal transmission module 3 is transmitted to the controller module for detection and judgment;

[0015] S2, close the main switch SB1 and the rising switch SB2, the coil of the rising relay KM1 is energized, so that the three contacts of the rising relay KM1 are all closed, the rising signal light ZHD lights up, and the three-phase motor runs to make the hoist rise. The first limiter and the second limiter are normal. If the three-phase motor does not run, the output limiter is faulty;

[0016] S3, when the spreader rises to the set height of the first limiter, the current between the second collection point and the third collection point is collected. If the current between the second collection point and the third collection point remains unchanged, the first limiter is in a fault state. If the current between the second collection point and the third collection point increases, the first limiter is in a normal state.

[0017] S4, close the circuit breaker to connect the second collection point with the third collection point. When the spreader continues to rise and reaches the set height of the second limiter, collect the voltage of the second collection point. If the voltage of the second collection point is 0, the second-level limiter is in a normal state. If the voltage of the second collection point is not 0, the second-level limiter is in a fault state.

[0018] On the basis of the above technical solution, preferably, the step S1 of wirelessly transmitting the collected voltage and current signals to the signal transmission module includes the following sub-steps:

[0019] The voltage and current signals collected by each collection point of the relay are sent through wireless transmission. The digital signal received by each sensor node of the signal transmission module is expressed as:

[0020] x ∈ R N ;

[0021] In the formula, x is the data matrix, R N express N dimensional real number space, x Each point is included R Position N data points;

[0022] S12, use matrix low rank approximation to decompose the data matrix to obtain a low rank approximation matrix x m ;

[0023] S13, using the LEC algorithm to compress the low-rank approximation matrix into a length of k bits, and split the bit stream into equal R bit slice, get the compressed signal y， The expression is:

[0024] y = LEC ( x m );

[0025] y ∈ R K , K = k / R ;

[0026] S14, the compressed signal is converted into a base station vector through random projection redundant coding, which is expressed as:

[0027] z=A y

[0028] In the formula, z is the base station vector, A is the random matrix, A∈ R N*K ;

[0029] S15, the relay node transmits the base station vector as a communication signal to the base station.

[0030] On the basis of the above technical solution, preferably, the step S13 of decomposing the data matrix using matrix low-rank approximation to obtain a low-rank approximation matrix includes the following sub-steps:

[0031] Singular value decomposition is used to approximately decompose the data matrix into the product of three matrices, expressed as:

[0032] x=U Σ VT

[0033] In the formula, U is an orthogonal matrix, Σ is a diagonal matrix, V T is the transposed matrix of another orthogonal matrix;

[0034] Before selection m Singular value truncated diagonal matrix Σ , obtain a low-rank approximate matrix x m , the expression is:

[0035] x m =U m Σ m V m T

[0036] In the formula, U m , Σ m and V m They are U , Σ and V Before the Matrix m List.

[0037] On the basis of the above technical solution, preferably, it also includes:

[0038] When there is data packet loss in the base station vector, the lost data points are obtained according to the index sub-matrix and the received data points of the base station vector.

[0039] On the basis of the above technical solution, preferably, the step of obtaining the lost data points according to the received data points of the index sub-matrix and the base station vector comprises the following sub-steps:

[0040] Get the received data points of the base station vector, the expression is:

[0041]

[0042] In the formula, is the received data point of the base station vector, is the submatrix of the index of the random matrix A, where ;

[0043] Recover the submatrix of the index of the random matrix A, the expression is:

[0044]

[0045] In the formula, yes The transpose of

[0046] The inverse process of the LEC algorithm is used to decode the recovered data to obtain the original data, and the expression is:

[0047] x m =ILEC ( y ).

[0048] The crane double limiter detection system and method of the present invention have the following beneficial effects compared with the prior art:

[0049] (1) By setting the four collection points of the collection module at the input end of the double limiter module, between the first-level limiter and the second-level limiter, and at the output end of the double limiter module, the voltage and current at each point are collected respectively, and the collected voltage and current signals are wirelessly transmitted to the signal transmission module, which is then transmitted to the controller module for detection and judgment of the working status of the two limiters, thereby realizing comprehensive real-time monitoring of the working status of the double limiters of the crane, preventing safety hazards, and improving safety;

[0050] (2) The wireless transmission method uses sparse matrix projection and matrix low-rank approximation to introduce random redundancy into the encoded data, thereby effectively offsetting the relay data loss during wireless transmission; and uses a redundant matrix with more rows to project artificial data points of the LEC compressed bit stream; this artificially injected redundancy makes it robust to data loss of any signal that can be compressed by LEC. This method can provide lossless reconstruction of the original wireless signal with extremely high probability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 This is a structural principle block diagram of a crane double limiter detection system of the present invention;

[0053] Figure 2 A circuit diagram of a double stopper module of a double stopper detection system for a crane according to the present invention;

[0054] Figure 3It is a structural schematic diagram of a signal transmission module of a crane double limiter detection system of the present invention;

[0055] Figure 4 It is a flow chart of a method for detecting double limiters of a crane according to the present invention;

[0056] Figure 5 The present invention is a random redundant coding flow chart of a crane double limiter detection method. DETAILED DESCRIPTION

[0057] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] like Figure 1-3 As shown, in the first aspect, the present invention provides a double limiter detection system for a crane, the system comprising: a double limiter module 1, an acquisition module 2, a signal transmission module 3 and a controller module 4, wherein the acquisition module 2 is electrically connected to the double limiter module 1, the acquisition module 2 has four acquisition points, the first acquisition point is arranged at the input end of the double limiter module 1, the second acquisition point and the third acquisition point are arranged between the first-level limiter and the second-level limiter, and the fourth acquisition point is arranged at the output of the double limiter module 1, for collecting the working voltage and current signals of the double limiter; the signal transmission module 3 is communicatively connected to the acquisition module 2, the controller module 4 is electrically connected to the signal transmission module 3, and the collected signal is transmitted to the controller module 4 through the signal transmission module 3 for processing.

[0059] The working principle of the existing double limiter of the crane is: two limiters with different limit heights are used to limit the hoisting height of the crane. When the limiter with a lower limit height is damaged, the limiter with a higher height can further perform anti-top protection, which plays a double insurance role. Here, the limiter with a lower limit height is called the first limiter, and the limiter with a higher limit height is called the second limiter. Under normal circumstances, when the spreader rises to the first limit height, the first limiter triggers the first limit switch ZWK1 to disconnect it, so that the spreader stops rising. When the first limiter is damaged, when the spreader rises to the second limit height, the second limiter triggers the second limit switch ZWK2 to disconnect it, so that the spreader stops rising.

[0060] In this embodiment, the four collection points of the collection module 2 are respectively set at the input end of the double limiter module 1, between the first-level limiter and the second-level limiter, and the output end of the double limiter module 1, and the voltage and current of each point are collected respectively. The collected voltage and current signals are wirelessly transmitted to the signal transmission module 3, and the signal transmission module 3 transmits them to the controller module 4 to detect and judge the working status of the two limiters, thereby realizing comprehensive real-time monitoring of the working status of the double limiter of the crane, preventing safety hazards, and improving safety.

[0061] In this embodiment, the dual limiter module 1 includes a three-phase motor, an ascending relay KM1, a descending relay KM2, a fuse, a main switch SB1, an ascending switch SB2, a descending switch SB3, a first limit switch ZWK1, a second limit switch ZWK2, a low limit switch FWK, an ascending signal light ZHD, a descending signal light FHD and a thermal relay, wherein the ascending relay KM1 and the descending relay KM2 each have three contacts, the three-phase motor is electrically connected to the first contacts of the ascending relay KM1 and the descending relay KM2 and the fuse respectively, the other end of the first contact of the ascending relay KM1 and the descending relay KM2 is commonly connected to the coil of the thermal relay, the other end of the coil of the thermal relay is electrically connected to the three-phase motor, the other end of the fuse is electrically connected to the main switch SB1, the other end of the main switch SB1 is electrically connected to the second contact of the ascending relay KM1, the second contact of the descending relay KM2, the ascending switch SB2 and the descending switch SB3 respectively, the ascending switch SB2 is electrically connected to the ascending relay The other end of the second contact of electrical appliance KM1 is commonly connected to the second limit switch ZWK2, the other end of the second limit switch ZWK2 is electrically connected to the first limit switch ZWK1, the other end of the first limit switch ZWK1 is electrically connected to the third contact of the descending relay KM2, the other end of the third contact of the descending relay KM2 is electrically connected to the coil of the ascending relay KM1 and the ascending signal light ZHD respectively, the descending switch SB3 and the other end of the second contact of the descending relay KM2 are commonly connected to the low limit switch FWK, the other end of the low limit switch FWK is electrically connected to the third contact of the ascending relay KM1, the other end of the third contact of the ascending relay KM1 is electrically connected to the coil of the descending relay KM2 and the descending signal light FHD respectively, the other end of the coil of the ascending relay KM1 and the other end of the ascending signal light ZHD and the other end of the coil of the descending relay KM2 and the other end of the descending signal light FHD are commonly electrically connected to the contact of the thermal relay, and the other end of the contact of the thermal relay is electrically connected to the neutral line.

[0062] It should be noted that the first contact and the second contact of the rising relay KM1 are both in the normally open state, and the third contact is in the closed state. The first contact and the second contact of the falling relay KM2 are both in the normally open state, and the third contact is in the normally closed state. The first limit switch ZWK1 and the second limit switch ZWK2 are in the normally closed state. When the first limit switch senses that the hoist has risen to the corresponding specified height, the first limit switch ZWK1 is disconnected. When the second limit switch senses that the hoist has risen to the corresponding specified height, the second limit switch ZWK2 is disconnected.

[0063] Under normal circumstances, the ascent control:

[0064] Turn on the main switch SB1 and the rising switch SB2. The current passes through the main switch SB1, the second contact of the rising relay KM1, the second limit switch ZWK2, the first limit switch ZWK1, and the third contact of the descending relay KM2 to reach the coil of the rising relay KM1 and output to the neutral line. The coil of the rising relay KM1 is powered on, so that the first contact and the second contact of the rising relay KM1 are closed, and the third contact is disconnected. Then the three currents are passed to the three-phase motor to work, so that the hoisting device rises and moves. At the same time, the rising signal light ZHD lights up. When the specified height corresponding to the first limiter is reached, the first limit switch ZWK1 is disconnected, and the current is disconnected. The coil of the rising relay KM1 loses power and the three-phase motor stops working.

[0065] Descent Control:

[0066] When the main switch SB1 is turned on and closed, and the descending switch SB3 is pressed, the current passes through the main switch SB1, the second contact of the descending relay KM2, the low limit switch FWK, and the third contact of the ascending relay KM1 to reach the coil of the descending relay KM2 and output to the neutral line. The coil of the descending relay KM2 is powered on, so that the first contact and the second contact of the descending relay KM2 are closed, and the third contact is disconnected. Then three currents are passed to the three-phase motor to work, causing the hoist to descend and move. At the same time, the descending signal light FHD lights up. When the specified height corresponding to the low limiter is reached, the low limit switch FWK is disconnected, and the current is disconnected, the coil of the descending relay KM2 loses power, and the three-phase motor stops working.

[0067] The collection module 2 in this embodiment is a wireless communication relay, the first collection point of the wireless communication relay is electrically connected to the other end of the main switch SB1, the second collection point of the wireless communication relay is electrically connected to the other end of the second limit switch ZWK2, the third collection point of the wireless communication relay is electrically connected to the other end of the first limit switch ZWK1, the fourth collection point of the wireless communication relay is electrically connected to the other end of the contact of the thermal relay, and a circuit breaker is also provided between the second collection point of the wireless communication relay and the third collection point of the wireless communication relay.

[0068] In this embodiment, the signal transmission module 3 includes a wireless collector and a radio station. The wireless collector communicates wirelessly with the collection module 2 . The wireless collector and the radio station communicate signals via an RS485 interface. The radio station is electrically connected to the controller module 4 .

[0069] In addition, this embodiment further comprises a display screen module, the input end of which is electrically connected to the output end of the controller module 4 , and is used to display the dual limiter status information detected by the output of the controller module 4 .

[0070] like Figure 4-5 As shown, in a second aspect, the present invention further provides a crane double limiter detection method, which is implemented by the crane double limiter detection system as described above, and the method comprises the following steps:

[0071] S1, the four collection points of the collection module 2 are respectively set at the input end of the double limiter module 1, between the first-level limiter and the second-level limiter, and the output end of the double limiter module 1, and the voltage and current of each point are collected respectively, and the collected voltage and current signals are wirelessly transmitted to the signal transmission module 3, and the signal transmission module 3 transmits them to the controller module 4 for detection and judgment;

[0072] S2, close the main switch SB1 and the rising switch SB2, the coil of the rising relay KM1 is energized, so that the three contacts of the rising relay KM1 are all closed, the rising signal light ZHD lights up, and the three-phase motor runs to make the hoist rise. The first limiter and the second limiter are normal. If the three-phase motor does not run, the output limiter is faulty;

[0073] S3, when the spreader rises to the set height of the first limiter, the current between the second collection point and the third collection point is collected. If the current between the second collection point and the third collection point remains unchanged, the first limiter is in a fault state. If the current between the second collection point and the third collection point increases, the first limiter is in a normal state.

[0074] S4, close the circuit breaker to connect the second collection point with the third collection point. When the spreader continues to rise and reaches the set height of the second limiter, collect the voltage of the second collection point. If the voltage of the second collection point is 0, the second-level limiter is in a normal state. If the voltage of the second collection point is not 0, the second-level limiter is in a fault state.

[0075] It should be noted that the four collection points of the collection module 2 are respectively set at the corresponding positions of the double limiter module 1. The collection points are used to collect the voltage and current signals of each point in real time. The collection module 2 transmits these signals to the signal transmission module 3 through wireless communication. The signal transmission module 3 then transmits the signals to the controller module 4 through the RS485 interface or other wired communication methods for detection and judgment, closing the main switch SB1 and the rising switch SB2, so that the coil of the rising relay KM1 is energized, thereby triggering the closure of the three contacts of KM1. If everything is normal, the rising signal light ZHD will light up, and the three-phase motor will start to run. Turn, drive the hoist to rise. If the three-phase motor does not run, it means that there is a fault in the rising process. At this time, further judge whether the first limit switch ZWK1 or the second limit switch ZWK2 is damaged. When it is necessary to detect whether the first limiter is normal, under normal circumstances, the first limit switch ZWK1 is closed. When it reaches its limit height, if the first limit switch ZWK1 cannot be disconnected, the current between the second collection point and the third collection point remains unchanged. At this time, the screen displays that the first limiter is faulty; if the first limit switch ZWK1 can be disconnected, the current between the second collection point and the third collection point increases. At this time, the screen displays that the first limiter is normal. When it is necessary to detect whether the second limiter is normal, the circuit breaker is controlled to close. When the limit height is reached, if the second limit switch ZWK2 cannot be disconnected, the voltage at the second collection point is not 0. At this time, the screen displays that the second limiter is faulty. Under normal circumstances, the second limit switch ZWK2 is closed and disconnected when the limit height is reached. The voltage at the first collection point remains unchanged, and the voltage at the second collection point becomes 0. At this time, the screen displays that the second limiter is normal.

[0076] In the wireless transmission process of the signal in this process, an improved lossless entropy compression data transmission method is used. This method can perform lossless compression to reduce energy consumption in signal transmission. The lossy method sacrifices the details of the original signal in exchange for a higher compression ratio. In the present invention, a lossless method is selected instead of a lossy method to retain the complete information of the data in the wireless transmission.

[0077] The basic idea of ​​lossless entropy compression is to divide the alphabet of numbers into groups according to their entropy. As the entropy grows, the size of the group grows exponentially; LEC then uses a combination of two codes, a unary code to specify the group and a binary code to specify the index within the group, to fully represent a number; The first step of the LEC algorithm is to generate an alternate data series called a difference signal, which is generated using the difference between every two consecutive data points in the original series.

[0078] After compressing the data using LEC, a shortened bit stream is obtained at the wireless relay node. In order to reconstruct the original data, the bit stream needs to be reliably transmitted to the base station through the lossy wireless link. For this purpose, different methods are available; however, methods based on reactive retransmission are not as flexible and efficient as those based on redundant coding due to delays and traffic congestion.

[0079] The step S1 of wirelessly transmitting the collected voltage and current signals to the signal transmission module 3 includes the following sub-steps:

[0080] The voltage and current signals collected by each collection point of the relay are sent through wireless transmission. The digital signal received by each sensor node of the signal transmission module 3 is expressed as:

[0081] x ∈ R N ;

[0082] In the formula, x is the data matrix, R N express N dimensional real number space, x Each point is included R Position N data points;

[0083] We first use a matrix low-rank approximation to decompose x into the product of multiple smaller, simpler matrices, which usually have lower ranks. This method can reveal hidden, simplified structures in relay data.

[0084] S12, use matrix low rank approximation to decompose the data matrix to obtain a low rank approximation matrix x m ;

[0085] Singular value decomposition is used to approximately decompose the data matrix into the product of three matrices, expressed as:

[0086] x=U Σ V T

[0087] In the formula, U is an orthogonal matrix, Σ is a diagonal matrix, V T is the transposed matrix of another orthogonal matrix;

[0088] Before selection m Singular value truncated diagonal matrix Σ , obtain a low-rank approximate matrix x m , the expression is:

[0089] x m =U m Σ m V m T

[0090] In the formula, U m , Σ m and V m They are U , Σ and V Before the Matrix m List.

[0091] In SVD, Σ The diagonal elements of are called singular values, which are arranged in descending order. To achieve low-rank approximation, we can truncate Σ by retaining the first m singular values, and then obtain a low-rank approximation matrix x m .

[0092] S13, using the LEC algorithm to compress the low-rank approximation matrix into a length of k bits, and split the bit stream into equal R bit slice, get the compressed signal y， The expression is:

[0093] y = LEC ( x m );

[0094] y ∈ R K , K = k / R ;

[0095] Among them, K is only 40%-70% of N, depending on the compression ratio of LEC, and y is converted into x through the LEC dictionary.

[0096] S14, the compressed signal is converted into a base station vector through random projection redundant coding, which is expressed as:

[0097] z=A y

[0098] In the formula, z is the base station vector, A is the random matrix, A∈ R N*K ;

[0099] S15, the relay node transmits the base station vector as a communication signal to the base station.

[0100] The method further includes: when a data packet is lost in the base station vector, the lost data point is obtained according to the index sub-matrix and the received data point of the base station vector.

[0101] On the basis of the above technical solution, preferably, the step of obtaining the lost data points according to the received data points of the index sub-matrix and the base station vector comprises the following sub-steps:

[0102] Get the received data points of the base station vector, the expression is:

[0103]

[0104] In the formula, is the received data point of the base station vector, is the submatrix of the index of the random matrix A, where ;

[0105] Recover the submatrix of the index of the random matrix A, the expression is:

[0106]

[0107] In the formula, yes The transpose of

[0108] The inverse process of the LEC algorithm is used to decode the recovered data to obtain the original data, and the expression is:

[0109] x m =ILEC ( y ).

[0110] This wireless transmission method uses sparse matrix projection and matrix low-rank approximation to introduce random redundancy into the encoded data, thereby effectively offsetting the relay data loss during wireless transmission; on the other hand, a redundant matrix with more rows is used to project artificial data points of the LEC-compressed bit stream; this artificially injected redundancy makes it robust to data loss of any signal that can be compressed by LEC.

[0111] Injecting redundancy into the LEC bitstream causes its size to increase; however, it is important to cap its size from an upper bound to avoid excessive transmission leading to longer delays and higher energy consumption. In the proposed method, the size of the final coded data with redundancy is equal to the size of the original N data points, i.e., N·R bits. After two stages of encoding, transmitting the same coded bit payload as the original bits has higher robustness and reliability against data loss.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A crane double limiter detection system, characterized in that: The system comprises: a dual stopper module, a collection module, a signal transmission module and a controller module, wherein the collection module is electrically connected to the dual stopper module, the collection module has four collection points, the first collection point is arranged at the input end of the dual stopper module, the second collection point and the third collection point are arranged between the first-level stopper and the second-level stopper, and the fourth collection point is arranged at the output of the dual stopper module, for collecting the working voltage and current signals of the dual stopper; the signal transmission module is communicatively connected to the collection module, the controller module is electrically connected to the signal transmission module, and the collected signal is transmitted to the controller module for processing through the signal transmission module; The double limiter module includes an ascending relay KM1, a descending relay KM2, a main switch SB1, an ascending switch SB2, a descending switch SB3, a first limit switch ZWK1, a second limit switch ZWK2, a low limit switch FWK, an ascending signal light ZHD, a descending signal light FHD and a thermal relay. The ascending relay KM1 and the descending relay KM2 each have three contacts. One end of the main switch SB1 is electrically connected to the second contact of the ascending relay KM1, the second contact of the descending relay KM2, the ascending switch SB2 and the descending switch SB3 respectively. The other end of the ascending switch SB2 and the second contact of the ascending relay KM1 are commonly connected to the second limit switch ZWK2. The other end of the second limit switch ZWK2 is electrically connected to the first limit switch ZWK1. The other end of the second contact of the lowering relay KM2 is electrically connected to the third contact of the lowering relay KM2, the other end of the third contact of the lowering relay KM2 is electrically connected to the coil of the raising relay KM1 and the raising signal light ZHD respectively, the lowering switch SB3 and the other end of the second contact of the lowering relay KM2 are commonly connected to the low limit switch FWK, the other end of the low limit switch FWK is electrically connected to the third contact of the raising relay KM1, the other end of the third contact of the raising relay KM1 is electrically connected to the coil of the lowering relay KM2 and the lowering signal light FHD respectively, the other end of the coil of the raising relay KM1 and the other end of the rising signal light ZHD as well as the other end of the coil of the lowering relay KM2 and the other end of the lowering signal light FHD are commonly connected to the contact of the thermal relay, and the other end of the contact of the thermal relay is electrically connected to the neutral line.

2. The crane double limiter detection system according to claim 1, characterized in that: The dual limiter module (1) further comprises a three-phase motor and a fuse, wherein the three-phase motor is electrically connected to the first contacts of the rising relay KM1 and the falling relay KM2 and the fuse respectively, the other ends of the first contacts of the rising relay KM1 and the falling relay KM2 are commonly connected to the coil of the thermal relay, the other end of the coil of the thermal relay is electrically connected to the three-phase motor, and the other end of the fuse is electrically connected to the main switch SB1.

3. The crane double limiter detection system according to claim 2, characterized in that: The acquisition module (2) is a wireless communication relay, wherein a first acquisition point of the wireless communication relay is electrically connected to the other end of the main switch SB1, a second acquisition point of the wireless communication relay is electrically connected to the other end of the second limit switch ZWK2, a third acquisition point of the wireless communication relay is electrically connected to the other end of the first limit switch ZWK1, a fourth acquisition point of the wireless communication relay is electrically connected to the other end of the contact of the thermal relay, and a circuit breaker is further provided between the second acquisition point of the wireless communication relay and the third acquisition point of the wireless communication relay.

4. The crane double limiter detection system according to claim 3, characterized in that: The signal transmission module (3) comprises a wireless collector and a radio station. The wireless collector communicates wirelessly with the collection module (2). The wireless collector and the radio station communicate signals via an RS485 interface. The radio station is electrically connected to the controller module (4).

5. The crane double limiter detection system according to claim 1, characterized in that: It also comprises a display screen module, the input end of the display screen module being electrically connected to the output end of the controller module (4) and being used to display the dual limiter status information detected by the output of the controller module (4).

6. A crane double stopper detection method, implemented by using a crane double stopper detection system as claimed in any one of claims 2 to 5, characterized in that: The method comprises the following steps: S1, four collection points of the collection module (2) are respectively set at the input end of the double stopper module (1), between the first-stage stopper and the second-stage stopper, and at the output end of the double stopper module (1), and the voltage and current at each point are respectively collected, and the collected voltage and current signals are wirelessly transmitted to the signal transmission module (3), and the signal transmission module (3) transmits them to the controller module (4) for detection and judgment; S2, close the main switch SB1 and the rising switch SB2, the coil of the rising relay KM1 is energized, so that the three contacts of the rising relay KM1 are all closed, the rising signal light ZHD lights up, and the three-phase motor runs to make the hoist rise. The first limiter and the second limiter are normal. If the three-phase motor does not run, the output limiter is faulty; S3, when the spreader rises to the set height of the first limiter, the current between the second collection point and the third collection point is collected. If the current between the second collection point and the third collection point remains unchanged, the first limiter is in a fault state. If the current between the second collection point and the third collection point increases, the first limiter is in a normal state. S4, close the circuit breaker to connect the second collection point with the third collection point. When the spreader continues to rise and reaches the set height of the second limiter, collect the voltage of the second collection point. If the voltage of the second collection point is 0, the second-level limiter is in a normal state. If the voltage of the second collection point is not 0, the second-level limiter is in a fault state.

7. The crane double limiter detection method according to claim 6, characterized in that: The step S1 wirelessly transmits the collected voltage and current signals to the signal transmission module (3), which includes the following sub-steps: S11, the voltage and current signals collected by each collection point of the relay are sent through wireless transmission, and the digital signal received by each sensor node of the signal transmission module (3) is expressed as: x ∈ R N ； In the formula, x is the data matrix, R N express N dimensional real number space, x Each point is included R Position N data points; S12, use matrix low rank approximation to decompose the data matrix to obtain a low rank approximation matrix x m ; S13, using the LEC algorithm to compress the low-rank approximation matrix into a length of k bits, and split the bit stream into equal R bit slice, get the compressed signal y， The expression is: y = LEC ( x m )； y ∈ R K ， K = k / R ； S14, the compressed signal is converted into a base station vector through random projection redundant coding, which is expressed as: z=A y In the formula, z is the base station vector, A is the random matrix, A∈ R N*K ; S15, the relay node transmits the base station vector as a communication signal to the base station.

8. The method for detecting double limiters of a crane according to claim 7, characterized in that: The step S13 of using matrix low-rank approximation to decompose the data matrix to obtain a low-rank approximation matrix includes the following sub-steps: Singular value decomposition is used to approximately decompose the data matrix into the product of three matrices, expressed as: x=U S V T In the formula, U is an orthogonal matrix, Σ is a diagonal matrix, V T is the transposed matrix of another orthogonal matrix; Before selection m Singular value truncated diagonal matrix Σ , obtain a low-rank approximation matrix x m , the expression is: x m =U m Σ m V m T In the formula, U m , Σ m and V m They are U , Σ and V Before the Matrix m List.

9. The crane double limiter detection method according to claim 8, characterized in that: Also includes: When there is data packet loss in the base station vector, the lost data points are obtained according to the index sub-matrix and the received data points of the base station vector.

10. The crane double limiter detection method according to claim 9, characterized in that: The step of obtaining the lost data points according to the received data points of the index sub-matrix and the base station vector comprises the following sub-steps: Get the received data points of the base station vector, the expression is: In the formula, is the received data point of the base station vector, is the submatrix of the index of the random matrix A, where ; Recover the submatrix of the index of the random matrix A, the expression is: In the formula, yes The transpose of The inverse process of the LEC algorithm is used to decode the recovered data to obtain the original data, and the expression is: x m =ILEC ( y )。

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