A SAW RFID-based precise positioning method and system for a hook lug of a metallurgical ladle

Abstract

The application discloses a kind of based on SAWRFID's metallurgical ladle hook ear precision positioning method and system.Method includes: establishing space coordinate system, in the center of ladle ear and hook respectively deploying first, second SAWRFID tag and reader antenna;Through antenna emission radio frequency signal and receive the backscattering signal returned by tag;According to the phase change of first label, solve the current position coordinate of ear;According to the multi-phase data generated by second label in the process of hook movement, adopt synthetic aperture technology to solve the current position coordinate of hook;Calculate the relative offset of both, according to the preset safety threshold value to determine matching state, realize the precision alignment and safety monitoring of hook and ear.System includes high-temperature-resistant SAWRFID tag unit, double-antenna reader unit, signal processing unit and linkage control unit, constitute closed-loop control from sensing, processing to execution.The application can improve the positioning accuracy and safety of metallurgical ladle lifting operation, avoid the safety accident caused by alignment deviation.

Description

Technical Field

[0001] This invention relates to the field of positioning hook lugs for metallurgical steel ladles, and more particularly to a method and system for precise positioning of hook lugs for metallurgical steel ladles based on SAWRFID. Background Technology

[0002] The metallurgical ladle is a core piece of equipment for transferring molten steel in the steelmaking process. Precise positioning of the hook and lugs (trunnions) is crucial for the lifting and transfer of the ladle, and its accuracy and reliability directly affect production safety and operational efficiency. Traditional positioning methods rely on visual observation and coordinated operation by the driver and ground control personnel, which suffers from large subjective errors, cumbersome operation, and delayed response. In the high-temperature (ladle surface temperature can reach over 350℃), dusty, and poorly lit conditions of a metallurgical workshop, visibility is extremely low, easily leading to misalignment of the hook and lugs, causing accidents such as hook slippage, hook jamming, or even ladle detachment, seriously threatening personnel safety and the stability of production equipment.

[0003] In existing technologies, GPS positioning cannot be applied due to signal obstruction in the enclosed environment of workshops; laser ranging and coded cables are complex to deploy, require production interruption for installation and maintenance, and are easily affected by smoke and dust, impacting accuracy; traditional RFID tags are unstable in high-temperature environments, and signals are susceptible to multipath fading and environmental noise interference. Although surface acoustic wave (SAW) RFID technology has high-temperature resistance, existing SAW RFID positioning methods are mostly based on distance detection, with ranging errors reaching tens of centimeters, and require the deployment of multiple antennas, increasing system complexity and deployment costs, making it difficult to meet the high-precision, low-cost positioning requirements of metallurgical ladle hook lugs.

[0004] Therefore, developing an automated positioning technology that can adapt to the harsh working conditions of metallurgy and has the characteristics of high precision, high stability and easy deployment has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] To address the problems of large positioning errors, high deployment costs, and poor adaptability to harsh working conditions in existing metallurgical ladle hook lug positioning technologies, this invention proposes a precise positioning method and system for metallurgical ladle hook lugs based on SAWRFID to solve the above technical problems. The specific solution is as follows:

[0006] A method for precise positioning of hook lugs on metallurgical steel ladles based on SAWRFID, characterized by the following steps:

[0007] S1. Establish a spatial coordinate system, fix a first SAW RFID tag at the center of the ladle loop, deploy a second SAW RFID tag on the hook, and set a first reader antenna corresponding to the first SAW RFID tag and a second reader antenna corresponding to the second SAW RFID tag.

[0008] S2. The first reader antenna and the second reader antenna transmit radio frequency signals to the corresponding first SAWRFID tag and the second SAWRFID tag, and receive the returned backscattered signals;

[0009] S3. Based on the phase change of the backscattered signal of the first SAWRFID tag, calculate the current position coordinates of the ear loop using the geometric mapping method;

[0010] S4: Based on the multiple phase data generated by the second SAWRFID tag during the hook's movement, the current position coordinates of the hook are calculated using synthetic aperture technology;

[0011] S5: Calculate the relative offset between the current position coordinates of the hook and the lug, and determine the matching status of the two based on the offset.

[0012] Furthermore, in step S1, the spatial coordinate system uses a fixed point designated within the workshop as the spatial origin and defines three orthogonal axes, namely the X-axis, Y-axis, and Z-axis.

[0013] The X-axis is parallel to the horizontal movement direction of the hook to align with the hook ear;

[0014] The Y-axis is perpendicular to the vertical direction of the ground;

[0015] The Z-axis is perpendicular to the plane formed by the X-axis and the Y-axis;

[0016] The first SAWRFID tag is fixed to the surface of the steel ladle lug, and its installation direction is parallel to the X-axis. The installation direction is the maximum radiation direction.

[0017] The first reader antenna is deployed with its radiating surface facing the first SAWRFID tag and is constrained within a vertical plane defined by the X and Y axes, thereby ensuring that the displacement of the first SAWRFID tag along the X axis can be directly mapped to a deterministic change in the straight-line distance between the first SAWRFID tag and the first reader antenna.

[0018] The second SAWRFID tag is fixed to the hook, with its installation direction parallel to the Z-axis.

[0019] Several second reader antennas are deployed along the X-axis, with their radiating surfaces facing the radiating surfaces of the second SAWRFID tags, to collect the backscattered signals of the second SAWRFID tags during the hook's movement.

[0020] Furthermore, in step S3, the calculation of the current position coordinates of the ear hook using the geometric mapping method specifically includes:

[0021] The displacement deviation of the loop in the X-axis direction is mapped to the first SAW RFID tag and... The formula for calculating the change in distance between them is: , The first SAW RFID tag and The change in distance between them, denoted by m, is a preset mapping coefficient achieved by adjusting the antenna height. This represents the displacement deviation of the lug in the X-axis direction;

[0022] The distance change is calculated by analyzing the phase difference of the backscattered signal. ,in For radio frequency signal wavelength, The wavelength of the electromagnetic wave reflected when the first tag is located in the real-time phase. The wavelength of the electromagnetic wave reflected when the first tag is in the initial phase;

[0023] Based on the distance change Calculate the real-time X-coordinate of the ear loop center: ,in The initial X coordinate of the first SAW RFID tag.

[0024] Furthermore, in step S4, the calculation of the hook's current position coordinates using synthetic aperture technology specifically includes:

[0025] The hook drives the second SAWRFID tag to move at a constant speed along the X-axis. The second reader antenna collects N phase data generated by the second SAWRFID tag during its constant speed movement at fixed intervals, forming a phase vector.

[0026] A virtual antenna array is constructed using the virtual positions of the second reader antenna at N acquisition times;

[0027] The phase vector is processed by a pattern matching algorithm to obtain the estimated X-coordinate of the second SAW RFID tag that maximizes the matching function;

[0028] The real-time X-coordinate of the center of the hook groove is determined based on the estimated X-coordinate value.

[0029] Furthermore, in step S5, determining the matching state specifically means: if the absolute value of the relative offset between the hook and the lug along the X-axis is less than or equal to a preset safety threshold. If the match is successful, the match is considered reliable and lifting is permitted; otherwise, the match is considered unreliable and lifting is not permitted.

[0030] Furthermore, the security threshold R1 is the radius of the hook tip, R2 is the radius of the hook lug, and α is the minimum safe contact angle.

[0031] A precise positioning system for implementing the method described above, characterized in that it comprises:

[0032] The high-temperature resistant SAW RFID tag unit includes a first SAW RFID tag deployed at the center of the ladle lug and a second SAW RFID tag deployed on the hook;

[0033] The dual-antenna reader unit includes a first reader antenna corresponding to the first SAWRFID tag and a second reader antenna corresponding to the second SAWRFID tag. The first reader antenna and the second reader antenna are mounted on a fixed structure adjacent to the hook's movement path and are used to transmit radio frequency signals and receive backscattered signals from the tags.

[0034] A signal processing unit, deployed locally, is used to process the backscattered signal and execute the algorithm as described in steps S3 to S5 of the method above to calculate the position coordinates and determine the matching state.

[0035] The linkage control unit is communicatively connected to the signal processing unit and the drive mechanism that drives the hook to move. It is used to receive the matching status determination result and output a horizontal displacement adjustment command or a safety warning signal to the drive mechanism accordingly.

[0036] The high-temperature resistant SAW RFID tag unit, dual-antenna reader unit, signal processing unit, and linkage control unit are connected in sequence to form a closed-loop control system from signal perception, processing to execution feedback, which works together to achieve the alignment and monitoring of the hook and ear.

[0037] Furthermore, the reader antenna in the dual-antenna reader unit is a directional antenna; the core of the signal processing unit is a field-programmable gate array, hereinafter referred to as FPGA, which has a built-in phase calculation module, geometric mapping positioning module and synthetic aperture positioning module.

[0038] Furthermore, the linkage control unit is configured to execute the following control logic:

[0039] Receive the matching status determination result from the signal processing unit;

[0040] When the determination result is an unreliable match, a horizontal displacement adjustment command is output to the drive mechanism;

[0041] During the lifting process, the real-time offset is continuously received from the signal processing unit. and with the security threshold If the offset exceeds the safety threshold, an emergency braking warning signal is triggered to the drive mechanism and the safety alarm device.

[0042] The beneficial effects of this invention are as follows:

[0043] 1. Overcame the precision bottleneck of traditional technologies under harsh working conditions.

[0044] This invention abandons traditional ranging methods that rely on signal strength and optical sensors that rely on vision, and utilizes the phase information of the backscattered signal from SAW tags as the basis for precision measurement. Based on this, an algorithm combining "static hook geometric mapping positioning" and "dynamic hook phase-based synthetic aperture positioning" overcomes the effects of strong electromagnetic interference and metal multipath effects in metallurgical workshops.

[0045] 2. Stable operation of the technology under high-temperature environments has been achieved.

[0046] To address the persistently high temperatures surrounding the steel ladle, the core of this invention—the SAW tag unit—is custom-designed using a 128°YX-cut lithium niobate piezoelectric substrate. Since the tag contains no silicon-based semiconductor chip and operates solely through piezoelectric effect and sound wave reflection, it can withstand temperatures ranging from -20°C to 400°C, far exceeding the operating limits of traditional IC-type RFID tags. This allows the front end of the entire positioning system (the tag) to be directly attached to the hot steel ladle surface, solving the problem of sensor failure in high-temperature areas.

[0047] 3. Significantly reduced the system's implementation complexity and overall cost.

[0048] The entire positioning system requires only two passive SAW tags and two directional antennas to simultaneously locate two independent moving targets: a hook and a lug. This deployment scheme eliminates the need for large-scale deployment of antenna arrays and cables in the workshop; the antennas can be fixedly installed on the structure near the movement route, allowing for installation and debugging without interrupting production.

[0049] 4. Improved intrinsic safety level

[0050] The system can calculate the relative offset between the hook and the lug in real time and make automatic safety judgments based on geometric parameters. In the event of an "unreliable match," the linkage control unit can immediately output a horizontal displacement adjustment command to the drive mechanism to guide automatic calibration. During the lifting process, the system continuously monitors the system, and if the offset exceeds the limit, it triggers an emergency braking warning. This transforms passive safety, which relies on human experience, into proactive and preventative safety guaranteed by reliable technology, greatly reducing the risk of safety accidents caused by human misjudgment or operational delays. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the core decision logic of the system in an embodiment of the present invention;

[0052] Figure 2 This is the closed-loop control and replanning process according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the hook movement in an embodiment of the present invention.

[0054] Figure 4 This is a schematic diagram showing the installation orientation of components according to an embodiment of the present invention;

[0055] In the attached diagram: hook 1, hanging ear 2. Detailed Implementation

[0056] To make the objectives and technical solutions of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples.

[0057] To address the problems of large positioning errors, high deployment costs, and poor adaptability to harsh working conditions in existing metallurgical ladle hook lug positioning technologies, this invention proposes a precise positioning method and system for metallurgical ladle hook lugs based on SAWRFID to solve the above technical problems. The specific solution is as follows:

[0058] A method for precise positioning of hook lugs on metallurgical steel ladles based on SAWRFID includes the following steps:

[0059] like Figure 4 As shown in the figure, X`Y`Z' are parallel to X, Y, and Z respectively, which is convenient for reference to spatial orientation. S1. Establish a spatial coordinate system, fix the first SAWRFID tag at the center of the ladle hanging ear 2, deploy the second SAWRFID tag on the hook 1, and set the first reader antenna corresponding to the first SAWRFID tag and the second reader antenna corresponding to the second SAWRFID tag; preferably, in step S1, the spatial coordinate system is defined with a fixed point designated in the workshop as the spatial origin, and three orthogonal axes are defined as the X-axis, Y-axis, and Z-axis; (For ease of reading and understanding of the formula, in the following text, the first SAWRFID tag is abbreviated as T1, the second SAWRFID tag is abbreviated as T2, the first reader antenna is A1, and the second reader antenna is A2. The abbreviations here are also used for the labels of the first SAWRFID tag, the second SAWRFID tag, the first reader antenna, and the second reader antenna in the attached figure.)

[0060] The X-axis is parallel to the hook 1 and is the direction of horizontal movement for aligning with the hook ear 2;

[0061] The Y-axis is perpendicular to the vertical direction of the ground;

[0062] The Z-axis is perpendicular to the plane formed by the X-axis and the Y-axis;

[0063] T1 is fixed to the surface of the steel ladle hanging lug 2, and its installation direction is parallel to the X-axis. The installation direction is the maximum radiation direction.

[0064] A1 is deployed with its radial surface facing T1 and is constrained within a vertical plane defined by the X and Y axes, thereby ensuring that the displacement of T1 along the X-axis can be directly mapped to a deterministic change in the straight-line distance between T1 and A1.

[0065] T2 is fixed to hook 1, and its installation direction is parallel to the Z-axis;

[0066] Several A2s are deployed along the X-axis, with their radiating surfaces opposite to the radiating surface of T2, to collect the backscattered signal of T2 during the movement of hook 1.

[0067] Specifically, the steps to establish a spatial coordinate system include: taking a fixed point within the workshop as the origin. =(0,0,0) establishes a spatial rectangular coordinate system and follows the right-hand rule.

[0068] as well as The coordinates are as and ;antenna , The coordinates are respectively and .

[0069] S2. A1 and A2 transmit radio frequency signals to their respective T1 and T2, and receive the returned backscattered signals.

[0070] Specifically, for S2, A1 continuously transmits a time-domain pulse signal of 915~930MHz to T1, while A2 synchronously transmits a signal of the same frequency band to tag T2;

[0071] After receiving the signal, the tag converts the electromagnetic wave into a surface acoustic wave through an IDT transducer, which then reflects the wave back through a reflector.

[0072] The reader receives the backscattered signal and transmits it to the FPGA signal processing unit.

[0073] The label uses a 128°YX-cutLiNbO3 piezoelectric substrate, equipped with a SPUDT transducer and multi-reflector structure, with a temperature range of -20℃ to 400℃ and an operating frequency of 915 to 930MHz.

[0074] The reader antenna is a positioning antenna with a gain of ≥9dBi, a horizontal half-power beamwidth of 68°, and a vertical half-power beamwidth of 60°. The reader has a built-in DDS signal generator, IQ demodulator, and FPGA core processing module, with a transmit power of 28dBm and a receive sensitivity of -90dBm.

[0075] S3. Based on the phase change of the backscattered signal of T1, the current position coordinates of the hook 2 are calculated using the geometric mapping method; the derivation process of this mapping relationship is as follows: Let the real-time coordinates of T1 be... Due to the positional deviation of the ladle, the label coordinates Relative to its initial coordinates There are deviations in the X-axis and Z-axis directions respectively. and ;

[0076] Because the lug 2 is fixed to the ladle, the Y-axis deviation... Real-time distance from tag T1 to antenna A1 .

[0077] Based on the Taylor expansion approximation: ,in, The initial coordinates of the label to antenna coordinates The distance.

[0078] By adjusting the height of antenna A1, Then the change in distance can be derived. ,in These are the mapping coefficients.

[0079] The distance change is calculated by analyzing the phase difference of the backscattered signal. ,in For radio frequency signal wavelength, ( At the speed of light, (This refers to the operating frequency). The wavelength of the electromagnetic wave reflected when the first tag is located in the real-time phase. The wavelength of the electromagnetic wave reflected when the first tag is in the initial phase;

[0080] Through the above Calculate the real-time X-coordinate of T1, and then obtain the X-coordinate of the center of ear loop 2. ,coordinate The calculation formula is

[0081]

[0082] S4: Based on the multiple phase data generated by T2 during the movement of hook 1, the current position coordinates of hook 1 are calculated using synthetic aperture technology; preferably, in step S4, the calculation of the current position coordinates of hook 1 using synthetic aperture technology specifically includes: hook 1 drives T2 to move at a constant speed along the X-axis, and A2 collects N phase data generated by T2 during the constant speed movement at fixed intervals to form a phase vector;

[0083] Hook 1 drives T2 to move at a constant speed along the X-axis. The speed of hook 1 is... , N phase data points are continuously acquired at a fixed interrogation interval (IRT) to form a phase vector. .

[0084] A virtual antenna array is constructed using the virtual positions of A2 at N acquisition times;

[0085] Construct a virtual antenna array, whose nth array element A2, n The coordinates are:

[0086]

[0087] The phase vector is processed by a pattern matching algorithm to obtain the estimated X-coordinate of T2 that maximizes the matching function;

[0088] The specific process is as follows: For the phase vector... Phase vector generated by virtual array Normalization is performed:

[0089]

[0090]

[0091] Find the optimal X-coordinate estimate of T2 using pattern matching:

[0092]

[0093] in For the conjugate transpose operator. It is a norm;

[0094] The real-time X-coordinate of the center of hook 1 is determined based on the estimated X-coordinate, i.e., the X-coordinate of the hook center. :

[0095]

[0096] S5: Calculate the relative offset between the current position coordinates of the hook 1 and the lug 2, and determine their matching status based on the offset. Preferably, in step S5, determining the matching status specifically means: if the absolute value of the relative offset between the hook 1 and the lug 2 along the X-axis is less than or equal to a preset safety threshold... If the match is successful, the match is considered reliable and lifting is permitted; otherwise, the match is considered unreliable and lifting is not permitted.

[0097] Specifically, the formula for calculating the relative offset is: The judgment condition is:

[0098]

[0099]

[0100] The former is a reliable match and lifting is permitted; the latter is an unreliable match and lifting is not permitted.

[0101] Preferably, the security threshold is based on The calculations show that R1 is the radius of the tip of hook 1, R2 is the radius of the lug 2, and α is the minimum safe contact angle.

[0102] If unreliable matching occurs, the overhead crane linkage control unit will... Output a horizontal displacement command and repeat the aforementioned steps until a reliable matching condition is met; continuous monitoring is performed during the lifting process. If the deviation exceeds the threshold, an early warning will be triggered immediately.

[0103] like Figure 1 As shown, a precise positioning system for implementing the method described above includes:

[0104] The high-temperature resistant SAW RFID tag unit includes a T1 deployed at the center of the ladle hanging ear 2 and a T2 deployed on the hook 1; specifically, T1 is fixed to the surface of the ladle hanging ear 2, and its installation direction is parallel to the X-axis, which is the maximum radiation direction.

[0105] The dual-antenna reader unit (directional antenna) includes A1 corresponding to T1 and A2 corresponding to T2. A1 and A2 are mounted on a fixed structure adjacent to the movement path of hook 1 and are used to transmit radio frequency signals and receive backscattered signals from the tag. A1 is deployed with its radiating surface facing T1 and is constrained within a vertical plane defined by the X-axis and Y-axis, thereby ensuring that the displacement of T1 along the X-axis can be directly mapped to a deterministic change in the straight-line distance between T1 and A1. The specific parameters of the reader unit and the high-temperature resistant SAW RFID tag unit have been described above and will not be repeated here.

[0106] The signal processing unit, whose core is a field-programmable gate array (FPGA), has a built-in phase calculation algorithm, geometric mapping positioning module and synthetic aperture positioning module. It is used to receive the phase signal collected by the reader, calculate the real-time position of the tag and calculate the relative offset between hook 1 and ear 2. The signal processing unit is deployed locally to process the backscattered signal and execute the algorithm of steps S3 to S5 mentioned above to calculate the position coordinates and determine the matching status.

[0107] The linkage control unit, also known as the crane linkage control unit, communicates bidirectionally with the crane control system. It outputs horizontal displacement and lifting height control commands based on the relative offset, and also incorporates a safety threshold judgment module to provide early warning and braking in case of positioning abnormalities. It is communicatively connected to the signal processing unit and the drive mechanism that drives the hook 1 (usually the crane itself; cranes are common drive mechanisms in this field and will not be described further here). It receives the matching status judgment result and outputs horizontal displacement adjustment commands or safety warning signals to the drive mechanism accordingly.

[0108] like Figure 1 As shown, preferably, the linkage control unit is configured to execute the following control logic:

[0109] Receive the matching status determination result from the signal processing unit;

[0110] When the determination result is an unreliable match, a horizontal displacement adjustment command is output to the drive mechanism;

[0111] During the lifting process, the real-time offset is continuously received from the signal processing unit. and with the security threshold If the offset exceeds the safety threshold, an emergency braking warning signal is triggered to the drive mechanism and the safety alarm device.

[0112] The high-temperature resistant SAW RFID tag unit, dual-antenna reader unit, signal processing unit and linkage control unit are connected in sequence to form a closed-loop control system from signal perception, processing to execution feedback, which works together to achieve the alignment and monitoring of hook 1 and ear 2.

[0113] The following is an implementation case study of a precise positioning method and system for metallurgical ladle hook lugs based on SAWRFID, combining... Figure 1 , Figure 2 , Figure 3 , Figure 4 :

[0114] 1. System Deployment and Coordinate System Establishment

[0115] This embodiment was implemented in a continuous casting workshop of a steel plant. The center of the bottom fixing bolt of a load-bearing column in the workshop was selected as the origin of the spatial coordinate system. =(0,0,0), and establish a global rectangular coordinate system following the right-hand rule.

[0116] X-axis: Parallel to the direction of the overhead crane's running track, i.e., the horizontal movement direction of hook 1 to align with ladle lug 2.

[0117] Y-axis: Perpendicular to the ground, with vertically upward as the positive direction. (It should be noted that the hook 1 can move not only along the X-axis but also up and down along the Y-axis.)

[0118] Z-axis: The plane perpendicular to the X-axis and Y-axis.

[0119] Tag and antenna deployment:

[0120] Steel ladle hanging ear tag (T1): Utilizes a high-temperature resistant SAW RFID tag with a 128°YX-cut LiNbO3 piezoelectric substrate, operating frequency band 915-930MHz, and temperature resistance up to 400℃. Securely weld T1 to the center of the outer surface of the right-side hanging ear 2 of the steel ladle to be hoisted. During installation, ensure the tag's maximum radiation direction is parallel to the X-axis.

[0121] Assuming its initial coordinates (standard parking position for steel ladles) are measured as follows: , Unit: meter.

[0122] Hook Tag (T2): A SAW RFID tag of the same model is securely installed on the steel structure near the groove of hook 1 on the right side of the overhead crane, ensuring its maximum radiation direction is parallel to the Z-axis. Its initial coordinates (hook retraction position) are denoted as... .

[0123] Reader antenna A1: A directional antenna with a gain of 9dBi. It is mounted on a fixed platform support near the ladle parking area, with the coordinates set as follows: During installation, strict calibration is required to ensure that the radiating surface is directly facing the initial position of T1, and that the antenna's azimuth and elevation angles are constrained within a vertical plane (i.e., the XOY plane) defined by the X and Y axes. This constraint is crucial for achieving geometric mapping, ensuring that the displacement of T1 in the X direction can be linearly translated into a change in distance between T1 and A1.

[0124] Reader antenna A2: Also a directional antenna. Three A2 antenna elements are deployed along the X-axis on the side of the hook 1's movement path, with coordinates as follows: =(10.0,7.0,-2.0), =(12.0,7.0,-2.0), =(14.0,7.0,-2.0). The radiating surfaces of all A2 antennas are oriented towards the trajectory of hook 1, and are used to collect the signal of T2 from different spatial locations during the movement of hook 1 (it should be noted that if the space is large, more antennas can be set on multiple opposite surfaces in order to obtain accurate movement data of hook 1).

[0125] 2. Location and Matching Determination Process

[0126] Steps S1-S2: System initialization and signal acquisition

[0127] After the system is powered on, the dual-channel reader unit drives antennas A1 and A2 (selecting one of them, such as A2-1 as the initial interrogation antenna) to synchronously transmit a time-domain pulse interrogation signal at a frequency of 920MHz. After T1 and T2 are activated, they convert electromagnetic energy into surface acoustic waves through their internal interdigital transducers (IDTs). The acoustic waves are reflected by a specially coded reflector array within the tag substrate and then converted back into electromagnetic waves for backscattering.

[0128] The reader receives these signals carrying unique phase information, which are then rapidly acquired and digitized by the FPGA signal processing unit. The system records the initial phase value of T1 at this point. .

[0129] Step S3: Loop 2 positioning based on geometric mapping

[0130] When the ladle shifts due to parking deviation or collision, the position of T1 becomes...

[0131] Since the loop 2 is fixed, Δy1=0.

[0132] Distance mapping relationship established: Calculate the initial distance d0 from the initial position of T1 to A1: d0 = |15.0 - 0.0| = 15.0 m. According to the plan, by adjusting the installation height (Y coordinate) of A1, the desired result is achieved. The condition is that, in this example, the mapping coefficient m=1.

[0133] Phase displacement calculation: FPGA calculates the phase of the T1 return signal in real time. According to the formula , where λ is the radio frequency wavelength (approximately 0.326m), and the change in distance Δd between T1 and A1 is calculated.

[0134] Calculate the coordinates of loop 2: Since m=1, therefore Δx1=Δd. The real-time X-coordinate of the center of loop 2 is x1= =15.0+Δd. This method transforms complex spatial distance measurement into high-precision phase measurement of displacement in a single direction, effectively improving the reliability and anti-interference capability of positioning.

[0135] Step S4: Positioning of hook 1 based on synthetic aperture

[0136] The crane operator moves hook 1 toward the ladle, and hook 1 drives T2 at a roughly constant speed. Motion along the X-axis at m / s.

[0137] Virtual array construction: The FPGA controls the reader to continuously acquire N=8 phase samples (T2) through antenna A2-1 at a fixed interrogation interval IRT=0.1s, forming a phase vector. Based on the synthetic aperture principle, the positions of the A2-1 antenna at these 8 sampling times are considered as a virtual linear array distributed along the X-axis, and the coordinates of its nth virtual element are... .

[0138] Pattern matching localization: The synthetic aperture localization module within the FPGA generates a set of reference phase vectors corresponding to the X coordinates of different hypothetical labels. By calculating the normalized measured vector With reference vector Find the cross-correlation coefficient (as described in the original text) and the estimated label X coordinate xT2,est that maximizes the correlation coefficient.

[0139] Calculate the coordinates of hook 1: Considering signal processing delay, the real-time X-coordinate of the center of hook 1 is x2 = Synthetic aperture technology creates spatial diversity by utilizing the motion of hook 1 itself, achieving the effect of multi-antenna direction finding with only a single physical antenna, significantly reducing system complexity and hardware cost.

[0140] Step S5: Matching Status Determination and Linkage Control

[0141] Calculate the relative offset: The signal processing unit calculates in real time the offset between hook 1 and lug 2 in the key alignment direction (X-axis). =|x1-x2|.

[0142] Safety threshold determination: Based on the user-provided safety parameters: hook 1 tip radius R1 = 0.1m, lug 2 radius R2 = 0.145m, minimum safe contact angle α = 35°. The maximum permissible offset safety threshold is calculated using the formula:

[0143] = = ≈10.47cm.

[0144] Control Decisions:

[0145] Alignment stage: If calculated in real time If the distance is greater than 10.47cm, the linkage control unit determines it as "unreliable matching" and immediately sends a command to the overhead crane control system via the wireless network to control the micro-movement of the overhead crane trolley and adjust the position of hook 1. At the same time, the system prompts "Please adjust the alignment".

[0146] Lifting conditions: When When the distance is ≤10.47cm, it is determined to be a "reliable match", and the system will light up the green lifting permission indicator light.

[0147] Continuous monitoring and early warning: The system continuously monitors the process of lifting and transporting steel ladles. If caused by ladle swaying If the limit is exceeded, the linkage control unit will immediately trigger an audible and visual warning and send the warning signal to the crane control system, suggesting deceleration or emergency braking, thus constructing a complete perception-decision-control safety closed loop.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for precise positioning of hook lugs on metallurgical steel ladles based on SAWRFID, characterized in that, Includes the following steps: S1. Establish a spatial coordinate system, fix a first SAW RFID tag at the center of the ladle loop, deploy a second SAW RFID tag on the hook, and set a first reader antenna corresponding to the first SAW RFID tag and a second reader antenna corresponding to the second SAW RFID tag. S2. The first reader antenna and the second reader antenna transmit radio frequency signals to the corresponding first SAWRFID tag and the second SAWRFID tag, and receive the returned backscattered signals; S3. Based on the phase change of the backscattered signal of the first SAWRFID tag, calculate the current position coordinates of the ear loop using the geometric mapping method; S4. Based on the multiple phase data generated by the second SAWRFID tag during the hook's movement, calculate the current position coordinates of the hook using synthetic aperture technology; S5. Calculate the relative offset between the current position coordinates of the hook and the lug, and determine the matching status of the two based on the offset.

2. The method for precise positioning of metallurgical ladle hook lugs based on SAWRFID according to claim 1, characterized in that, In step S1, the spatial coordinate system takes a fixed point designated within the workshop as its spatial origin and defines three orthogonal axes, namely the X-axis, Y-axis, and Z-axis. The X-axis is parallel to the horizontal movement direction of the hook to align with the hook ear; The Y-axis is perpendicular to the vertical direction of the ground; The Z-axis is perpendicular to the plane formed by the X-axis and the Y-axis; The first SAWRFID tag is fixed to the surface of the steel ladle lug, and its installation direction is parallel to the X-axis. The installation direction is the maximum radiation direction. The first reader antenna is deployed with its radiating surface facing the first SAWRFID tag and is constrained within a vertical plane defined by the X and Y axes, thereby ensuring that the displacement of the first SAWRFID tag along the X axis can be directly mapped to a deterministic change in the straight-line distance between the first SAWRFID tag and the first reader antenna. The second SAWRFID tag is fixed to the hook, with its installation direction parallel to the Z-axis. Several second reader antennas are deployed along the X-axis, with their radiating surfaces facing the radiating surfaces of the second SAWRFID tags, to collect the backscattered signals of the second SAWRFID tags during the hook's movement.

3. The method for precise positioning of metallurgical ladle hook lugs based on SAWRFID according to claim 2, characterized in that, In step S3, calculating the current position coordinates of the ear hook using the geometric mapping method specifically includes: The displacement deviation of the loop in the X-axis direction is mapped to the first SAW RFID tag and... The formula for calculating the change in distance between them is: , The first SAW RFID tag and The change in distance between them, denoted by m, is a preset mapping coefficient achieved by adjusting the antenna height. This represents the displacement deviation of the lug in the X-axis direction; The distance change is calculated by analyzing the phase difference of the backscattered signal. ,in For radio frequency signal wavelength, The wavelength of the electromagnetic wave reflected when the first tag is located in the real-time phase. The wavelength of the electromagnetic wave reflected when the first tag is in the initial phase; Based on the distance change Calculate the real-time X-coordinate of the ear loop center: ,in Let X be the initial X coordinate of the first SAW RFID tag.

4. The method for precise positioning of metallurgical ladle hook lugs based on SAWRFID according to claim 2, characterized in that, In step S4, calculating the current position coordinates of the hook using synthetic aperture technology specifically includes: The hook drives the second SAWRFID tag to move at a constant speed along the X-axis. The second reader antenna collects N phase data generated by the second SAWRFID tag during its constant speed movement at fixed intervals, forming a phase vector. A virtual antenna array is constructed using the virtual positions of the second reader antenna at N acquisition times; The phase vector is processed by a pattern matching algorithm to obtain the estimated X-coordinate of the second SAW RFID tag that maximizes the matching function; The real-time X-coordinate of the center of the hook groove is determined based on the estimated X-coordinate value.

5. The method for precise positioning of metallurgical ladle hook lugs based on SAWRFID according to claim 1, characterized in that, In step S5, determining the matching state specifically means: if the absolute value of the relative offset between the hook and the lug along the X-axis is less than or equal to a preset safety threshold. If the match is successful, the match is considered reliable and lifting is permitted; otherwise, the match is considered unreliable and lifting is not permitted.

6. The method for precise positioning of metallurgical ladle hook lugs based on SAWRFID according to claim 5, characterized in that, The security threshold R1 is the radius of the hook tip, R2 is the radius of the hook lug, and α is the minimum safe contact angle.

7. A precise positioning system for implementing the method as described in any one of claims 1 to 6, characterized in that, include: The high-temperature resistant SAW RFID tag unit includes a first SAW RFID tag deployed at the center of the ladle lug and a second SAW RFID tag deployed on the hook; The dual-antenna reader unit includes a first reader antenna corresponding to the first SAWRFID tag and a second reader antenna corresponding to the second SAWRFID tag. The first reader antenna and the second reader antenna are mounted on a fixed structure adjacent to the hook's movement path and are used to transmit radio frequency signals and receive backscattered signals from the tags. A signal processing unit, deployed locally, is used to process the backscattered signal and execute the algorithm of steps S3 to S5 as described in claim 1 to calculate the position coordinates and determine the matching state; The linkage control unit is communicatively connected to the signal processing unit and the drive mechanism that drives the hook to move. It is used to receive the matching status determination result and output a horizontal displacement adjustment command or a safety warning signal to the drive mechanism accordingly. The high-temperature resistant SAW RFID tag unit, dual-antenna reader unit, signal processing unit, and linkage control unit are connected in sequence to form a closed-loop control system from signal perception, processing to execution feedback, which works together to achieve the alignment and monitoring of the hook and ear.

8. The precise positioning system according to claim 7, characterized in that, The reader antenna in the dual-antenna reader unit is a directional antenna; the core of the signal processing unit is a field-programmable gate array (FPGA), which has a built-in phase calculation module, geometric mapping positioning module, and synthetic aperture positioning module.

9. The precise positioning system according to claim 7, characterized in that, The linkage control unit is configured to execute the following control logic: Receive the matching status determination result from the signal processing unit; When the determination result is an unreliable match, a horizontal displacement adjustment command is output to the drive mechanism; During the lifting process, the real-time offset is continuously received from the signal processing unit. and with the security threshold If the offset exceeds the safety threshold, an emergency braking warning signal is triggered to the drive mechanism and the safety alarm device.

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