A warning method for a boom that can be operated while charged and a boom

Abstract

The present invention discloses a warning method for a boom that can be operated while being energized and a boom, belonging to the technical field of safety monitoring for electric power construction. In this method, multiple electric field induction sensing nodes are arranged on the boom. By extracting the power frequency fundamental wave and its characteristic harmonics, an electric field spectrum fingerprint vector is constructed, and high-voltage lines are identified by using cosine similarity matching and spatial gradient consistency verification, effectively eliminating the interference of complex electromagnetic environments. At the same time, Kalman filtering is used to fuse the electric field distance estimation and encoder motion data to real-time estimate the distance, speed, and acceleration of the boom end, calculate the predicted braking distance including braking delay and sliding distance, and achieve hierarchical warning based on the safety margin. The present invention solves the problems of high false alarm rate in the prior art and insufficient braking distance due to warning lag, and significantly improves the safety of boom live working.

Description

Technical Field

[0001] This invention relates to the field of power construction safety monitoring technology, and in particular to a method for early warning of a crane boom that can be operated under power and the crane boom itself. Background Technology

[0002] With the widespread application of live-line working technology in the field of power maintenance, the frequency of operations of insulated boom cranes and other lifting machinery near energized high-voltage lines is increasing. In complex power construction environments, ensuring that the crane boom maintains a sufficient safe distance from energized high-voltage lines is crucial to protecting the lives of workers and ensuring the stable operation of the power grid.

[0003] Existing crane boom proximity warning technologies typically employ a single non-contact electric field sensor to monitor the surrounding electric field strength, triggering an alarm when the detected electric field strength exceeds a preset fixed threshold. However, this technology, based on a single sensor source and a fixed threshold for judgment, faces two significant challenges in practical applications.

[0004] On the one hand, the electromagnetic environment at construction sites is complex. Industrial equipment such as welding machines, transformers, and frequency converters can all generate electromagnetic interference in the same frequency band as the power line. Existing technologies, relying solely on simple comparisons of electric field strength thresholds, cannot distinguish between the power frequency electric field generated by the high-voltage line and the electromagnetic interference from on-site equipment based on signal characteristics. This deficiency leads to a situation where, under complex conditions with multiple interference sources, early warning devices are highly susceptible to misinterpreting interference signals as high-voltage approach signals, resulting in frequent false alarms. This can cause operators to experience warning fatigue and ignore genuine alarms; or the genuine high-voltage signal may be masked by interference signals, leading to the risk of missed alarms.

[0005] On the other hand, existing early warning systems generally adopt an instantaneous state judgment mode, that is, they decide whether to sound an alarm based solely on the sensor readings at the current moment, lacking the ability to predict the movement trend of the crane boom. Cranes typically have a large mechanical inertia. During high-speed rotation or luffing movements, even if the operator immediately applies the brakes after receiving a critical warning, the crane boom still needs to travel a certain physical braking distance to come to a complete stop. If the warning is only issued when the crane boom has reached the danger distance boundary, the mechanical braking distance and system response delay are ignored, which can easily cause the crane boom to exceed the safety boundary due to inertia during braking and enter the danger zone, leading to an electric shock accident. Summary of the Invention

[0006] This invention provides a method for early warning of a crane boom that can be operated under power and a crane boom in order to solve the technical problems of high false alarm rate caused by the inability of existing technology to distinguish between high voltage line electric field and environmental interference, and insufficient braking distance due to lack of motion trend prediction.

[0007] This invention provides a method for early warning of a crane boom that can be operated while energized, comprising the following steps:

[0008] Step S1: N electric field induction sensing nodes are set up along the length of the crane boom, N≥3; the main control unit synchronously collects the electric field induction signals of each electric field induction sensing node, and combines them with the slewing angle and amplitude angle signals of the crane boom.

[0009] Step S2: Perform short-time Fourier transform on the electric field induced signal to extract the amplitude and phase information of the power frequency fundamental wave and its characteristic harmonics, and construct the electric field spectrum fingerprint vector of each electric field induced sensing node.

[0010] Step S3: Perform cosine similarity matching between the electric field spectrum fingerprint vector and the pre-stored high-voltage line standard spectrum template library, and combine it with the fundamental amplitude spatial gradient consistency verification between adjacent electric field sensing nodes to determine whether there is a high-voltage line proximity event.

[0011] Step S4: If a high-voltage line proximity event is determined, the distance between the end of the crane boom and the high-voltage line is estimated using the high-voltage overhead line electric field attenuation model.

[0012] Step S5: Construct a state vector containing distance, approach velocity, and approach acceleration. Use the distance estimate and the radial motion velocity component of the boom end calculated from the slewing angle and the amplitude angle as the observation values, and use the Kalman filter algorithm to estimate the motion state of the boom end in real time.

[0013] Step S6: Calculate the predicted braking distance based on the approach speed estimate output by the Kalman filter and the current braking capacity parameters of the crane, and calculate the safety margin in conjunction with the minimum safe distance corresponding to the identified voltage level.

[0014] Step S7: Compare the safety margin with the graded warning threshold, and output the corresponding level of warning signal or braking control command.

[0015] As a preferred embodiment of the present invention, step S2, specifically comprising constructing the electric field spectral fingerprint vector, includes:

[0016] Extract the amplitude and phase of the fundamental frequency, third harmonic, and fifth harmonic;

[0017] Constructing a five-dimensional electric field spectral fingerprint vector ;

[0018] in, , , These represent the fundamental, third, and fifth harmonic amplitudes of the i-th sensing node, respectively. , , These are the corresponding phases.

[0019] As a preferred embodiment of the present invention, the specific logic for determining whether a high-voltage line proximity event exists in step S3 is as follows:

[0020] Calculate the cosine similarity between the electric field spectral fingerprint vector and the standard spectral template vector. If the maximum similarity is greater than a set threshold, the spectral matching is successful.

[0021] Calculate the difference sequence of fundamental amplitude between adjacent electric field induction sensing nodes along the direction of the crane boom. If the difference sequence satisfies the monotonically decreasing trend, the spatial gradient consistency check passes.

[0022] The high-voltage line proximity event is confirmed only when both the spectral matching and spatial gradient consistency checks pass simultaneously.

[0023] As a preferred embodiment of the present invention, in step S5, the radial motion velocity component of the arm end... The calculation formula is:

[0024] ;

[0025] in, This refers to the effective length of the crane boom. For variable angle, For variable angular velocity, The rotational angular velocity, It is the relative angle between the projection direction of the crane boom on the horizontal plane and the projection direction of the high-voltage line on the horizontal plane.

[0026] As a preferred embodiment of the present invention, in step S5, the process noise covariance matrix of the Kalman filter is calibrated according to the motion characteristics of the crane boom, the noise variance of the distance observation value in the observation noise covariance matrix is ​​set as a linear function related to the current distance estimate, and the noise variance of the speed observation value is set as a fixed value.

[0027] As a preferred embodiment of the present invention, in step S6, the braking distance is predicted. The calculation formula is: ;in, This is the approximate velocity estimate output by the Kalman filter. This represents the maximum braking deceleration under the current load. The total delay time from the warning system to the braking system; when When it is a non-positive value, Take zero.

[0028] As a preferred embodiment of the present invention, in step S6, the safety margin The calculation formula is: ;in, This is the distance estimate output by the Kalman filter. The minimum legal safety distance corresponding to the identified voltage level.

[0029] As a preferred embodiment of the present invention, the hierarchical early warning logic in step S7 includes:

[0030] when When triggered, a prompt-level warning is issued, providing only an audio-visual alert;

[0031] when When this occurs, a warning level alert is triggered, issuing an audible and visual warning and limiting the crane boom's movement speed;

[0032] when When this occurs, an emergency warning is triggered, an emergency alarm is issued, and the crane boom movement mechanism is forcibly locked.

[0033] in .

[0034] The present invention also provides an electrically operable lifting boom, including a boom body, a slewing mechanism, a luffing mechanism, a hydraulic control system, and an early warning system, wherein the early warning system is configured to execute the early warning method described in any of the above preferred technical solutions.

[0035] As a preferred embodiment of the present invention, the early warning system includes at least three non-contact capacitively coupled electric field sensing nodes installed along the length of the boom, an embedded main control unit installed on the slewing platform, and an audible and visual alarm terminal in the cab; the electric field sensing nodes include a bandpass filter with a center frequency of 50Hz.

[0036] The present invention can bring the following beneficial effects:

[0037] 1. This invention constructs an electric field spectral fingerprint vector containing harmonic amplitude ratios and phase relationships. Utilizing a decision mechanism combining cosine similarity matching and multi-node spatial gradient consistency verification, it effectively identifies the inherent spectral and spatial distribution characteristics of high-voltage lines, significantly distinguishing real high-voltage signals from electromagnetic interference generated by welding machines, frequency converters, and other equipment at construction sites. This technical solution reduces the false alarm rate to below 5% and the false alarm rate to below 2% under complex operating conditions, effectively solving the problem of warning fatigue caused by single-threshold judgment in existing technologies.

[0038] 2. This invention introduces motion state estimation based on Kalman filtering, combines the current approach speed, acceleration, and system delay parameters of the crane boom to calculate and predict the braking distance in real time, and uses the safety margin after deducting the braking distance as the basis for triggering the warning. This method increases the warning time lead to 2-4 seconds, providing sufficient reaction and braking buffer space for operators and the braking system, effectively avoiding safety accidents caused by braking lag of a large inertia crane boom. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the layout and signal processing principle of the electric field induction sensing nodes on the crane arm according to the present invention.

[0040] Figure 2 This is a hardware architecture block diagram of the crane boom early warning system according to a specific embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the overall process of the crane boom early warning method of the present invention.

[0042] Reference numerals: 1. Crane boom body; 2. Electric field induction sensing node. Detailed Implementation

[0043] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can fully understand and implement the technical solution of the present invention.

[0044] This embodiment provides a method for early warning of a crane boom that can be operated energized, and a crane boom itself. The technical solution lies in... Figure 1 As shown, multiple electric field sensing nodes 2 are deployed along the length of the crane boom 1. An embedded main control unit performs electric field spectrum fingerprint extraction and matching discrimination on the signals collected from each node. Combined with the crane boom's own motion parameters, it performs motion state estimation based on Kalman filtering and hierarchical feedforward early warning, thereby achieving accurate identification and early warning of dangerous approach events during construction near high-voltage power lines. The entire scheme's signal processing chain is divided into four layers: a sensing acquisition layer, a signal processing layer, an intelligent decision layer, and an early warning output layer. These layers are connected by a sequential closed-loop data processing architecture.

[0045] like Figure 2 As shown, regarding the sensor acquisition layer, sensors are installed at equal intervals along the length of the crane boom 1. 2. Non-contact capacitively coupled electric field sensing node. Not less than 3, preferably 3 in this embodiment. Numbered sequentially from the base of the arm to the tip of the arm. , , , Each sensing node includes an electric field sensing plate and a front-end analog signal conditioning circuit. This conditioning circuit includes a bandpass filter with a center frequency of [missing information]. The passband range is to This is used to preserve the fundamental frequency and first few characteristic harmonic components while suppressing the effects of DC offset and high-frequency radio frequency noise. The analog output signals from each sensor node are fed into the embedded main control unit installed on the slewing platform of the crane boom via shielded cables. The core processor of the main control unit uses an ARM Cortex-M7 level microprocessor with a clock frequency of no less than [missing information]. It is equipped with a 4-channel synchronous sampling analog-to-digital converter, with each channel having a sampling rate of no less than [missing information]. The resolution is no less than 16 bits to ensure strict synchronization of multi-channel signals in time. In the sensing acquisition layer, the main control unit also simultaneously receives the slewing angle encoder signal and the amplitude angle encoder signal of the crane boom itself to obtain the current geometric attitude parameters of the crane boom, providing observational basis for subsequent motion state estimation.

[0046] Regarding the early warning output layer, an audible and visual alarm terminal is installed in the cab, which includes a tri-color LED indicator group, a buzzer, and a voice broadcast module. Simultaneously, the main control unit is connected to the crane's hydraulic control system's brake lock-up interface via a CAN bus or hardwired connection, enabling it to issue a brake lock-up command to the hydraulic system upon triggering the highest-level warning, thereby achieving forced stop control of the crane boom's movement mechanism.

[0047] Based on the aforementioned hardware architecture, the early warning method of this invention includes two core algorithm processes as follows: Figure 3 As shown, the two run sequentially in the software inside the main control unit, forming a complete closed-loop processing link from physical signal acquisition to early warning output.

[0048] The first algorithm process involves electric field spectrum fingerprint extraction and matching. The main control unit uses a sampling rate... right Each channel is sampled synchronously. Each sampling window takes... Each sampling point corresponds to a 1-second time-domain data length, with an overlap rate of 50% between adjacent windows, meaning an analysis result is output every 0.5 seconds. A Hanning window function is applied to the digital sampling sequence within each frame window. Specifically, the window function... ,in The introduction of the Hanning window can effectively reduce spectral leakage and improve the accuracy of subsequent frequency point extraction.

[0049] After completing the windowing process, for the first Execution of windowed signal sequences for each channel Point Fast Fourier Transform yields a complex sequence in the frequency domain. The amplitude and phase information at three key frequency points are accurately located and extracted from the frequency domain sequence. Frequency domain index corresponding to the fundamental wave Its amplitude phase . Frequency domain index corresponding to the third harmonic Its amplitude phase . Frequency domain index corresponding to the fifth harmonic Its amplitude phase .

[0050] Based on the extracted amplitude and phase parameters, the first... A five-dimensional electric field spectrum fingerprint vector is constructed from individual sensing nodes. In this vector, the first component is The absolute amplitude of the fundamental frequency wave directly reflects the electric field strength level at the location of the sensing node. The second and third components are the amplitude ratios of the third and fifth harmonics relative to the fundamental wave, respectively, essentially characterizing the total harmonic distortion (THD) structure of the signal. The fourth and fifth components are the phase deviation values ​​between each harmonic and the fundamental wave. It should be noted that due to the inherent transmission line characteristics of high-voltage transmission lines, the phase deviations between each harmonic and the fundamental wave in their radiated electric field exhibit a relatively stable characteristic value distribution. While common equipment at construction sites, such as welding machines and frequency converters, also generate electromagnetic radiation in the power frequency and its harmonic bands, the statistical characteristics of their harmonic phase deviations differ significantly from those of high-voltage lines. This difference constitutes the core physical basis for distinguishing real high-voltage line signals from environmental electromagnetic interference, and is also the fundamental starting point for this invention's judgment based on the signal's spectral characteristics rather than simply amplitude.

[0051] After the fingerprint vector is constructed, it is matched with a standard spectrum template library pre-stored in the main control unit's Flash memory. This template library pre-stores standard spectrum template vectors for several voltage levels of high-voltage lines. ,in , Total number of templates. Template library coverage. , , , Four typical voltage levels are included, each containing 3 to 5 template variants obtained from measured calibration under different operating conditions. These different operating conditions include, but are not limited to, full load, light load, no load, and different weather conditions, with a total of approximately 16 to 20 template vectors. The template vectors are obtained as follows: under interference-free standard operating conditions, using the same sensor hardware and signal processing procedures as this system, actual data acquisition and spectrum analysis are performed on high-voltage lines of known voltage levels. The resulting fingerprint vectors are then normalized and stored in the template library.

[0052] For the current number fingerprint vector of each sensor node With template Calculate cosine similarity between them After traversing all template vectors in the template library, the maximum similarity value is taken. .when At that time, the judgment of the first The signal currently detected by each sensor node matches the spectral characteristics of the high-voltage line. In this embodiment, A value of 0.85 is recommended. This value maintains sufficient sensitivity to real high-voltage line signals while effectively suppressing mismatches caused by common interference sources in the construction environment. In different application scenarios, this threshold can be adaptively adjusted within the range of 0.80 to 0.92 according to the complexity of the on-site electromagnetic environment.

[0053] After successful spectral matching, a multi-node spatial gradient consistency check is required for further reliability confirmation. Specifically, this involves calculating the consistency between adjacent sensor nodes along the crane boom direction. Difference sequence of fundamental amplitude ,in Because the power frequency electric field generated by high-voltage lines exhibits a continuous and gradually varying characteristic in space, with the electric field strength increasing closer to the line, when the end of the crane boom faces the high-voltage line, the difference in fundamental amplitude between adjacent nodes along the boom root to boom end should show a monotonically unchanging trend. The verification rule is set as follows: In In a pair of adjacent differences, if at least one If all adjacent pairs satisfy the gradient increment condition, the spatial gradient consistency check passes. If a situation occurs where the spectrum matches but the spatial gradient is inconsistent, such as a sudden change in the amplitude of a signal at only one sensor node while its adjacent nodes show no corresponding change, then the signal is determined to originate from a local electromagnetic interference source rather than the high-voltage line, and the system does not trigger an alarm. This spatial verification mechanism utilizes the spatial continuity of the electric field of a high-voltage line, effectively identifying false alarms caused by the activation of a local interference device at the construction site.

[0054] The comprehensive decision logic is as follows: a high-voltage line proximity event is confirmed only when both spectral fingerprint matching and spatial gradient consistency verification pass simultaneously. After confirmation, the system marks the location of the sensor node with the largest fundamental amplitude as the "closest approach point," and outputs the determined high-voltage line voltage level information based on the voltage level number of the node's best matching template, for subsequent distance estimation and warning threshold selection. In this embodiment, at least two sensor nodes must simultaneously pass the threshold determination and spatial gradient consistency verification before subsequent processing can be triggered. This multi-node joint decision mechanism significantly improves the reliability of the judgment results compared to methods relying on a single sensor node.

[0055] The second algorithm process involves motion state estimation and hierarchical feedforward early warning based on Kalman filtering. After confirming the high-voltage line proximity event, the system enters the distance estimation and motion state tracking stage.

[0056] Distance estimation is based on the fundamental amplitude of the power frequency electric field detected by the nearest proximity sensor node. and the identified line voltage levels As input, an inverse solution is performed based on the theoretical model of electric field attenuation in high-voltage overhead lines. For a single overhead conductor, the power frequency electric field strength at a certain observation point in space approximately satisfies... ,in The shortest distance from the observation point to the traverse line. The height of the conductor above the ground. Let be the equivalent radius of the conductor. The electric field distortion coefficient of the crane boom's metal body represents the enhancement effect of the induced charge on the surrounding electric field. Its value is greater than 1, typically between 2.5 and 5.0. Specific values ​​are obtained through actual measurement calibration of this crane boom model under a standard electric field environment. The distance estimation value is then derived from this. Among them, the height of the conductor above the ground Typical values ​​for different voltage levels are stored in the system parameter table, such as... Line take , Line take , Line take , Line take ; equivalent radius of conductor The standard conductor model parameters corresponding to the voltage level are also pre-stored. This distance estimate serves as the input for subsequent distance observations in the Kalman filter. It should be noted that the above electric field attenuation model has certain theoretical approximation errors under different conductor arrangements and grounding conditions, especially with a decrease in accuracy at long distances. This characteristic has been specifically considered in the setting of the observation noise parameters for the Kalman filter.

[0057] In motion state space modeling, state vectors are defined. ,in For the first The estimated distance between the end of the crane boom and the high-voltage line at each sampling time. To approximate the time-varying rate of speed (i.e., distance) and with a positive value in the direction of the track, To approximate acceleration, a uniformly accelerated motion model is adopted as the state transition equation: , , ,in The sampling period is consistent with the output period of the aforementioned spectrum analysis. This represents noise during the acceleration process. The above state transition equation can be written in matrix form as follows: The state transition matrix Process noise covariance matrix The values ​​of each component are calibrated based on the smoothness of the actual motion characteristics of the crane boom.

[0058] Observation vector It contains two components. The first component... This is the estimated value for the electric field distance mentioned above. The second component... This refers to the radial velocity component of the boom tip, calculated by combining the angular velocity signals from the slewing angle encoder and the luffing angle encoder with the boom's geometric parameters. The specific calculation method for the boom tip radial velocity is as follows: ,in This refers to the effective length of the crane boom. For the current amplitude angle, For variable angular velocity, This refers to the rotational angular velocity. Parameter Defined as the relative angle (i.e., relative azimuth) between the projection direction of the crane boom onto the horizontal plane and the projection direction of the high-voltage line onto the horizontal plane. The method for obtaining the azimuth angle is as follows: before operation, the azimuth angle of the high-voltage line is obtained manually or automatically using an electronic compass, and then calculated by combining the absolute or relative azimuth angle output by the crane's rotary encoder. This speed calculation formula correctly decomposes and synthesizes the velocity components of the crane boom's slewing motion and luffing motion in the direction towards the high-voltage line using geometric projection, thereby obtaining the radial approach speed of the boom end relative to the high-voltage line.

[0059] The observation equation is expressed as The observation matrix That is, the distance observation directly corresponds to the distance component in the state vector, and the velocity observation directly corresponds to the velocity component. (Observation noise covariance matrix) ,in Based on the theoretical error characteristics of the electric field distance estimation model, and considering the physical law that the electric field gradient is large and the estimation accuracy is high at close range, while the accuracy decreases at long distance, it is set as a function related to the current observation distance: ,in This is a proportionality coefficient (typically ranging from 0.1 to 0.2). The baseline noise limit; The value is then set to a fixed value based on the encoder's own angular resolution and signal processing accuracy.

[0060] Within each sampling period, the Kalman filter executes according to the standard five-step recursive procedure. In the prediction step, prior state estimation... Prior covariance In the update step, the Kalman gain is calculated. Posterior state estimation Posterior covariance ,in It is a 3x3 identity matrix. After filtering and recursion, the output is the optimal state estimate at the current time step. These correspond to the noise-suppressed distance, approach velocity, and approach acceleration estimates, respectively. The introduction of Kalman filtering optimally weights and fuses the measurement noise caused by model simplification in electric field distance estimation with the encoder motion parameters, resulting in a significant improvement in the stability and accuracy of state estimation compared to a single observation source.

[0061] After obtaining the optimal state estimate, the system enters the braking distance prediction and graded warning decision stage. This is based on the current approach speed estimate output by the filter. And the parameters of the crane braking system under the current operating conditions are used to calculate the predicted braking distance. .in The maximum braking deceleration of the braking system under the current load conditions is calculated as follows: , The rated power for the braking system is given by the equipment's factory parameters. For the weight of the crane boom itself, The current lifting load is read in real time by the load sensor. This refers to the total delay time from when the warning system issues a braking command to when the braking system begins to generate effective braking force. This delay includes all aspects, including software processing delay, CAN bus communication transmission delay, and hydraulic system response delay. Its typical value range is... to The first term in the braking distance formula The theoretical sliding distance corresponding to the uniform deceleration braking process, the second term This corresponds to the distance the crane boom continues to move at the current speed during the system delay period. When approaching the estimated speed... When the value is non-positive, meaning the crane boom is moving away from the high-voltage line or is stationary, the braking distance is set to zero.

[0062] Based on this, define the safety margin index. ,in The minimum safe distance corresponding to the identified voltage level shall be determined with reference to the relevant provisions of the national standard GB 26164, specifically as follows: Pick , Pick , Pick , Pick Safety margin The physical meaning of this value is: the remaining usable distance space at the end of the crane boom after considering the distance required for braking and the legally mandated safety distance. The smaller this value, the closer the current working condition is to the danger boundary.

[0063] The tiered early warning decision logic sets three early warning thresholds. , , In this embodiment, Recommended value , Recommended value , Recommended value When safety margin and When a warning is triggered, a yellow LED indicator in the cab flashes, and the voice prompt module plays a message saying "Caution, approaching a high-voltage line." The system does not intervene in the movement of the crane boom. When the safety margin... and When a warning level is triggered, the red LED indicator in the cab remains constantly lit, the buzzer sounds intermittently, and the main control unit sends a speed-limiting command to the hydraulic control system via the CAN bus, limiting the slewing and luffing speeds of the crane boom to 30% of their maximum value. When the safety margin... This means that the current speed and braking capacity are insufficient to bring the crane boom to a complete stop before the legally required safe distance. At this point, an emergency warning is triggered, the red LED indicator in the cab flashes at a high frequency, the buzzer sounds continuously, and the voice broadcast module plays a voice warning, "Emergency! The safe distance is about to be exceeded!" At the same time, the main control unit sends a brake lock command to the hydraulic system via the CAN bus to forcibly stop all moving mechanisms.

[0064] The system has set clear conditions for lifting the warning status: when there are 3 consecutive sampling periods, i.e., consecutive... Approximate velocity estimate of the internal filter output All values ​​are negative, meaning the crane boom is continuously moving away from the high-voltage line, and the current estimated distance is... When the warning is triggered, the system automatically cancels the current warning status and resumes normal operation. This continuity judgment condition setting can prevent the warning status from frequently switching between triggering and canceling due to minor vibrations at the boom end or fluctuations in sensor noise.

[0065] All of the above processing steps are based on The system executes cyclically as a complete processing cycle. Within each cycle, the system sequentially completes all steps, including multi-channel synchronous acquisition and windowing of the electric field signal, fast Fourier transform spectrum extraction, five-dimensional spectral fingerprint vector construction, cosine similarity template matching, multi-node spatial gradient consistency verification, inverse solution of the electric field attenuation formula, encoder radial velocity calculation, Kalman filter state fusion, braking distance prediction, safety margin calculation, and three-level early warning decision and output. This ensures real-time, continuous, and uninterrupted monitoring and early warning capabilities throughout the entire operation of the crane boom.

[0066] In actual deployment, the number of the aforementioned sensor nodes installed... It can be adjusted according to the effective length of the boom and the on-site working environment. For small cranes with shorter booms, Setting it to 3 is sufficient to meet the basic requirements for spatial gradient verification; for arm lengths exceeding... For large cranes, up to five or more sensing nodes can be added to improve spatial resolution. The spacing between sensing nodes should be uniform, with the distance between adjacent nodes generally not exceeding one-third of the effective length of the boom. The electric field sensing plates of each sensing node should preferably be flat plates made of conductive material and insulated. Their effective sensing area is determined based on the target detection sensitivity requirements, with a typical range of values... to The induction plates should be installed with their normal direction facing outwards from the crane boom as much as possible to obtain the maximum coupling response to the external electric field.

[0067] For the maintenance and expansion of the template library, when the system needs to adapt to new voltage levels or special line structures, new spectrum template vectors can be collected and added to the template library according to the above standard calibration process, without modifying the algorithm logic itself. The template library is stored in the non-volatile Flash memory of the main control unit and supports on-site updates via the maintenance interface. In specific construction scenarios with particularly complex environmental electromagnetic interference, spectrum acquisition of the main interference sources on-site and construction of interference source elimination templates can be performed before formal operation, which can be used as a reverse matching reference to further improve the identification accuracy.

[0068] It is worth noting that the graded early warning threshold of this invention... , , and cosine similarity threshold These are not fixed constants. Users can adjust these parameters within a reasonable range according to actual needs, depending on the construction environment, the type of crane, and the operational requirements. For example, in nuclear power or chemical construction scenarios where safety margins are more stringent, the parameters can be appropriately increased. and The value of [value] can be selected to obtain earlier warnings; while in the relatively simple electromagnetic environment of suburban power line construction scenarios, the value can be appropriately reduced. The values ​​of these parameters are chosen to improve system sensitivity. Specific adjustments to these parameters are all conventional adaptive changes within the scope of the inventive concept and do not depart from the protection scope of this invention.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for early warning of a crane boom that can be operated while energized, characterized in that, Includes the following steps: Step S1: Install N electric field induction sensing nodes along the length of the crane boom, where N≥3; The main control unit synchronously collects the electric field sensing signals of each of the electric field sensing nodes, and combines them with the slewing angle and amplitude angle signals of the crane boom. Step S2: Perform a short-time Fourier transform on the electric field induced signal to extract the amplitude and phase information of the power frequency fundamental wave and its characteristic harmonics, and construct the electric field spectrum fingerprint vector of each electric field induced sensing node. Step S3: Perform cosine similarity matching between the electric field spectrum fingerprint vector and the pre-stored high-voltage line standard spectrum template library, and combine it with the fundamental amplitude spatial gradient consistency verification between adjacent electric field sensing nodes to determine whether there is a high-voltage line proximity event. Step S4: If a high-voltage line proximity event is determined, the distance between the end of the crane boom and the high-voltage line is estimated using the high-voltage overhead line electric field attenuation model. Step S5: Construct a state vector containing distance, approach velocity, and approach acceleration. Use the estimated distance value and the radial motion velocity component of the boom end calculated from the slewing angle and the amplitude angle as the observation value, and use the Kalman filter algorithm to estimate the motion state of the boom end in real time. Step S6: Calculate the predicted braking distance based on the approach speed estimate output by the Kalman filter and the current braking capacity parameters of the crane, and calculate the safety margin in conjunction with the minimum safe distance corresponding to the identified voltage level. Step S7: Compare the safety margin with the graded warning threshold, and output the corresponding level of warning signal or braking control command.

2. The early warning method for a energized crane boom according to claim 1, characterized in that, In step S2, constructing the electric field spectral fingerprint vector specifically includes: Extract the amplitude and phase of the fundamental frequency, third harmonic, and fifth harmonic; Construct a five-dimensional electric field spectral fingerprint vector; in, , , These represent the fundamental, third, and fifth harmonic amplitudes of the i-th sensing node, respectively. , , These are the corresponding phases.

3. The early warning method for a energized crane boom according to claim 1, characterized in that, In step S3, the specific logic for determining whether a high-voltage line proximity event exists is as follows: Calculate the cosine similarity between the electric field spectral fingerprint vector and the standard spectral template vector. If the maximum similarity is greater than a set threshold, the spectral matching is successful. Calculate the difference sequence of the fundamental amplitude between adjacent electric field sensing nodes along the direction of the crane boom. If the difference sequence satisfies the monotonically decreasing trend, the spatial gradient consistency check passes. The high-voltage line proximity event is confirmed only when both the spectral matching and spatial gradient consistency checks pass simultaneously.

4. The early warning method for a energized crane boom according to claim 1, characterized in that, In step S5, the radial motion velocity component of the arm end The calculation formula is: ； in, This refers to the effective length of the crane boom. For variable angle, For variable angular velocity, The rotational angular velocity, It is the relative angle between the projection direction of the crane boom on the horizontal plane and the projection direction of the high-voltage line on the horizontal plane.

5. The early warning method for a energized crane boom according to claim 1, characterized in that, In step S5, the process noise covariance matrix of the Kalman filter is calibrated according to the motion characteristics of the crane boom. The noise variance of the distance observation in the observation noise covariance matrix is ​​set as a linear function related to the current distance estimate, and the noise variance of the speed observation is set as a fixed value.

6. The early warning method for a energized crane boom according to claim 1, characterized in that, In step S6, the predicted braking distance The calculation formula is: ;in, This is the approximate velocity estimate output by the Kalman filter. This represents the maximum braking deceleration under the current load. The total delay time from the warning system to the braking system; when When it is a non-positive value, Take zero.

7. The method for early warning of a energized crane boom according to claim 6, characterized in that, In step S6, the safety margin The calculation formula is: ;in, This is the distance estimate output by the Kalman filter. The minimum legal safety distance corresponding to the identified voltage level.

8. The early warning method for a energized crane boom according to claim 1, characterized in that, The hierarchical early warning logic in step S7 includes: when When triggered, a prompt-level warning is issued, providing only an audio-visual alert; when When this occurs, a warning level alert is triggered, issuing an audible and visual warning and limiting the crane boom's movement speed; when When this occurs, an emergency warning is triggered, an emergency alarm is issued, and the crane boom movement mechanism is forcibly locked. in ; in, , , Three warning thresholds are set for the tiered warning judgment logic.

9. A crane boom capable of being operated electrically, comprising a boom body, a slewing mechanism, a luffing mechanism, a hydraulic control system, and an early warning system, characterized in that, The early warning system is configured to perform the early warning method according to any one of claims 1 to 8.

10. The electrically operable lifting boom according to claim 9, characterized in that, The early warning system includes at least three non-contact capacitively coupled electric field sensing nodes installed along the length of the boom, an embedded main control unit installed on the slewing platform, and an audible and visual alarm terminal in the cab; the electric field sensing nodes include a bandpass filter with a center frequency of 50Hz.

Images