3D printing modular electromagnetic adsorption multifunctional engineering working device and control method thereof

Abstract

The application provides a 3D printing modular electromagnetic adsorption multifunctional engineering operation device and a control method thereof, and relates to the technical field of intelligent control. The control method comprises the following steps: generating a pulse demagnetization control instruction according to a compensated total width value of a demagnetization pulse; driving a magnetic suction head to execute reverse magnetic field output according to the pulse demagnetization control instruction, so as to obtain a residual magnetism elimination state of a target iron piece surface; adjusting the extension length of an electric connecting rod according to the residual magnetism elimination state and the real-time load of a built-in overload sensor in a hand-held handle, so as to obtain a magnetic suction head space avoidance position; triggering an intelligent early warning module of a reserved anti-falling hanging point of a mounting seat according to the magnetic suction head space avoidance position, so as to obtain a falling risk evaluation result of the connecting rod. The application can accurately distinguish the fitting features of unilateral gap enlargement and the fitting features of overall gap reduction, so as to accurately evaluate the actual adsorption state of the end face of the magnetic suction head and the contact surface of the target iron piece, and reduce the iron piece slip risk.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology, and in particular to a 3D-printed modular electromagnetic adsorption multifunctional engineering operation device and its control method. Background Technology

[0002] Electromagnetic adsorption multifunctional engineering operation devices are widely used in building construction, infrastructure construction, and emergency safety scenarios for picking up, moving, and retrieving iron parts. These devices use a magnetic head to generate a magnetic field to attract target iron parts, and after the operation is completed, a pulse demagnetizing function eliminates residual magnetism to detach the iron parts.

[0003] Existing devices typically monitor only the steady-state current value of the coil when operating on narrow slits or uneven surfaces. When there is an inclination or local gap between the magnetic head end face and the target iron workpiece contact surface, edge magnetic leakage occurs. Current technology, relying solely on a single current value, cannot identify localized differences in the contact posture between the magnetic head end face and the target iron workpiece, leading to inaccuracies in the assessment of the attraction force and increasing the risk of the iron workpiece slipping off.

[0004] Existing devices typically use pulse demagnetization functions that output pulse sequences of fixed width. Because the residual magnetism distribution varies across different spatial bonding types, fixed-width demagnetization pulses cannot meet the actual needs of residual magnetism elimination. For thick iron parts, a fixed demagnetization energy results in incomplete residual magnetism elimination, leading to residual magnetism adhesion; for thin iron parts, a fixed demagnetization energy wastes energy and causes the iron parts to not detach smoothly. Summary of the Invention

[0005] This invention provides a 3D printing modular electromagnetic adsorption multifunctional engineering operation device and its control method, which can accurately distinguish between the bonding features of enlarged gap on one side and the bonding features of reduced gap on the whole side, thereby accurately assessing the actual adsorption state between the end face of the magnetic suction head and the contact surface of the target iron part, and reducing the risk of the iron part slipping off.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A first aspect is a control method for a 3D printing modular electromagnetic adsorption multifunctional engineering operation device, the method comprising: Step 1: Calculate the current difference between adjacent detection cycles based on the real-time current of the magnetic head coil collected by the controller inside the handheld handle, and obtain the change in magnetic resistance of the magnetic head adhering to the surface of the target iron piece. Step 2: Based on the change in magnetic resistance, match the real-time deflection angle of the universal bending node of the connecting rod to obtain the initial spatial fit characteristics between the end face of the magnetic suction head and the contact surface of the target iron piece. Step 3: Based on the initial spatial fit characteristics, classify the edge magnetic leakage degree of the magnetic chuck under narrow slot operation conditions to obtain the spatial fit category between the end face of the magnetic chuck and the contact surface of the target iron piece. Step 4: Based on the holding time period corresponding to the spatial fit category, the demagnetizing pulse width of the pulse generator in the mounting base is accumulated segment by segment to obtain the total width value of the demagnetizing pulse after compensation. Step 5: Generate a pulse demagnetization control command based on the compensated total width of the demagnetizing pulse; Step 6: According to the pulse demagnetization control command, drive the magnetic suction head to execute the reverse magnetic field output to obtain the residual magnetism elimination state of the target iron surface; Step 7: Based on the residual magnetism elimination state and the real-time load of the overload sensor built into the hand handle, adjust the extension length of the electric connecting rod to obtain the space avoidance position of the magnetic head. Step 8: Based on the space avoidance position of the magnetic head, trigger the intelligent early warning module of the pre-reserved anti-fall hanging point on the mounting base to obtain the fall risk assessment result of the connecting rod.

[0007] Secondly, a 3D printing modular electromagnetic adsorption multifunctional engineering operation device includes: The magnetic suction head has an excitation coil inside, which is wound axially on a coil frame. The end face of the magnetic suction head is used to adhere to and adsorb the surface of the target iron part. The mounting base is located on the non-adsorption end of the magnetic head. The mounting base integrates a pulse generator, and the output end of the pulse generator is electrically connected to the excitation coil inside the magnetic head. The side wall of the mounting base is reserved with anti-fall hanging points. The electric connecting rod has its front end connected to the mounting base. The electric connecting rod has a built-in telescopic drive motor and a universal bending node. An angle sensor is installed at the universal bending node. The handle connects to the rear end of the electric connecting rod. The handle contains a battery, a controller, and a weighing sensor. The controller is electrically connected to the current acquisition terminal of the excitation coil, the control terminal of the pulse generator, the drive terminal of the telescopic drive motor, the signal output terminal of the angle sensor, and the signal output terminal of the overload sensor. The fall arrest point integrates an intelligent early warning module, which communicates with the controller.

[0008] The above-described solution of the present invention has at least the following beneficial effects: By calculating the current difference between adjacent detection cycles and combining it with the real-time deflection angle of the universal bending node of the connecting rod, the degree of edge magnetic leakage of the magnetic suction head under narrow gap operation conditions is classified to obtain the spatial adhesion category. This process exposes the difference in mechanical response between the adsorption force eccentricity caused by unilateral edge magnetic leakage and the adsorption force attenuation caused by bilateral edge magnetic leakage. In narrow gap operations on construction sites, it can accurately distinguish the adhesion characteristics of unilateral gap amplification and the adhesion characteristics of overall gap reduction, thereby accurately assessing the actual adsorption state between the end face of the magnetic suction head and the contact surface of the target iron part, and reducing the risk of iron part slippage.

[0009] Based on the holding time corresponding to the spatial bonding category, the demagnetizing pulse width of the pulse generator inside the mounting base is accumulated segment by segment to obtain the compensated total demagnetizing pulse width value, which then drives the magnetic suction head to execute the reverse magnetic field output. This process exposes the difference in signal modulation between the asymmetric magnetic field reversal requirement corresponding to the single-sided bonding category and the symmetric magnetic field reversal requirement corresponding to the double-sided bonding category. In construction site demagnetization control, it can increase pulse width compensation for the hysteresis of deep magnetic domain reversal in thick-sized scrap iron residues, and rapidly attenuate and reduce pulse width for the surface magnetic domain reversal in thin-sized scrap iron residues, thereby smoothing out the residual magnetism peak, solving the problem of residual magnetism adhesion in thick-sized iron parts, and ensuring smooth detachment of iron parts.

[0010] Based on the residual magnetism elimination state and the real-time load adjustment of the extension length of the electric connecting rod, the spatial avoidance position of the magnetic suction head is obtained, and the intelligent early warning module of the fall arrest point is triggered. This process exposes the difference in structural instability modes between the overturning moment caused by the center of gravity shift during high-altitude cantilever operations and the buckling moment caused by axial compression during ground-level pushing operations. It can accurately assess the fall risk of the connecting rod and adapt to the fall safety requirements under complex working conditions. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the 3D printing modular electromagnetic adsorption multifunctional engineering operation device provided in the embodiments of the present invention.

[0012] Figure 2 This is a flowchart illustrating the control method of the 3D printing modular electromagnetic adsorption multifunctional engineering operation device provided in an embodiment of the present invention.

[0013] The reference numerals are: 1. Handle; 2. Connecting rod; 3. Mounting base; 4. Magnetic head. Detailed Implementation

[0014] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0015] Figure 1 The structure of the 3D printing modular electromagnetic adsorption multifunctional engineering work device of this embodiment is shown. The device includes a hand handle 1, an electric connecting rod 2, a mounting base 3, and a magnetic head 4, with each component connected sequentially along the axial direction.

[0016] The magnetic head 4 is the actuator that directly contacts the target iron part. An excitation coil is internally housed in the magnetic head 4, wound axially around a coil frame. The coil frame is integrally formed using 3D printing technology, and the material is glass fiber reinforced nylon with a tensile strength of not less than 80 MPa and a volume resistivity of not less than 10¹² Ω·cm, meeting the mechanical support and electrical isolation requirements of the electromagnetic adsorption device for the coil frame. The excitation coil is wound with enameled copper wire, and the number of turns is determined based on the diameter of the magnetic head end face and the required adsorption force. In this embodiment, the number of turns is 800 to 1200, and the radial cross-sectional area of ​​the coil is 78 to 113 square millimeters. The end face of the magnetic head 4 is a circular plane with a diameter of 80 to 120 millimeters, used to adhere to and adsorb the surface of the target iron part. When a direct current is passed through the excitation coil, a magnetic field perpendicular to the end face and outward is generated at the end face of the magnetic chuck. This magnetic field passes through the air gap between the end face and the surface of the target iron part and enters the interior of the iron part, forming a closed magnetic circuit, thereby generating an electromagnetic attraction force that attracts the iron part to the end face of the magnetic chuck.

[0017] Mounting base 3 is located at the non-attachment end of magnetic head 4, i.e., the rear end opposite the end face. Mounting base 3 is fixedly connected to magnetic head 4 via bolt flanges. An integrated pulse generator, an H-bridge drive circuit, is integrated within mounting base 3, capable of outputting forward excitation current and reverse demagnetization current to the excitation coil within magnetic head 4. The output of the pulse generator is electrically connected to the excitation coil within magnetic head 4 via a wire channel within mounting base 3. A fall arrest point is pre-installed on the side wall of mounting base 3, a through-hole structure for threading a safety rope or connecting external fall arrest equipment. An intelligent warning module is integrated at the fall arrest point, containing a microprocessor and a buzzer, capable of issuing audible and visual warning signals based on received fall risk assessment results. The intelligent warning module communicates with the controller within the handgrip 1 via a signal line within mounting base 3.

[0018] The electric connecting rod 2 is the intermediate force transmission component connecting the mounting base 3 and the hand handle 1. The front end of the electric connecting rod 2 is connected to the rear end of the mounting base 3 via a threaded interface. The electric connecting rod 2 adopts a multi-section telescopic sleeve structure and has a built-in telescopic drive motor. The telescopic drive motor is a DC geared motor, which converts the rotational motion of the motor into axial linear telescopic motion between the sleeve sections of the connecting rod through a screw and nut mechanism. A universal bending node is provided in the middle section of the electric connecting rod 2. The universal bending node uses a ball joint structure to achieve spatial angle adjustment between the front and rear halves of the connecting rod. An angle sensor is installed at the universal bending node. The angle sensor is an inertial measurement unit combining a triaxial accelerometer and a gyroscope, which can detect the deflection angle value at the universal bending node in real time, including pitch and roll angles. The signal line of the angle sensor passes through the central through hole of the ball joint structure of the universal bending node, extends along the wiring groove on the inner wall of the electric connecting rod to the hand handle, and connects to the corresponding signal input interface of the controller.

[0019] The handle 1 is connected to the rear end of the electric connecting rod 2 via a threaded interface. The handle 1 is the end component held by the operator; its outer shell is 3D printed in one piece, with an internal hollow cavity. The internal cavity of the handle 1 houses the battery, controller, and overload sensor. The battery is a rechargeable lithium battery, used to power the excitation coil, pulse generator, telescopic drive motor, angle sensor, controller, overload sensor, and intelligent warning module. The controller is a microcontroller or ARM processor, with a built-in analog-to-digital converter and multiple input / output interfaces. The controller's current acquisition terminal is connected to the two ends of the sampling resistor connected in series with the excitation coil inside the magnetic head 4, used to acquire the real-time current value of the excitation coil. The controller's control terminal is electrically connected to the control interface of the pulse generator and the drive interface of the telescopic drive motor, respectively. The controller's signal input terminal is electrically connected to the signal output terminals of the angle sensor and the overload sensor, respectively. The overload sensor is a strain gauge type tensile sensor, which is installed at the connection interface between the hand handle 1 and the electric connecting rod 2. Its sensitive axis coincides with the axial direction of the connecting rod, and it can detect the tensile load transmitted to the hand handle along the axial direction of the connecting rod in real time.

[0020] The shells and structural components of all the above parts are manufactured using 3D printing technology, with glass fiber reinforced nylon or carbon fiber reinforced polycarbonate as the printing materials. The modular design of 3D printing allows each component to be manufactured independently and quickly assembled, and to be replaced individually when a component is damaged.

[0021] Figure 2 The flowchart illustrates the control method of the 3D printing modular electromagnetic adsorption multifunctional engineering work device of this embodiment. The method is executed by a controller within the handheld handle 1 and includes the following steps.

[0022] Step 1: Calculate the change in magnetic reluctance The operator holds the handle 1 and brings the end face of the magnetic suction head 4 close to and against the surface of the target iron piece. During this process, the controller inside the handle 1 collects the real-time current value of the excitation coil inside the magnetic suction head 4 at fixed sampling intervals. The sampling interval is set between 10 and 50 milliseconds to balance the response speed to current changes and the power consumption of the controller's sampling channel.

[0023] The controller reads the first real-time current value of the excitation coil collected at the end of the current detection cycle, and retrieves the second real-time current value stored at the end of the previous adjacent detection cycle. It then calculates the difference between the first and second real-time current values ​​to obtain the excitation current difference between adjacent cycles.

[0024] As the magnetic head gradually comes into contact with the surface of the target iron part, the air gap between the end face and the iron part gradually decreases, and the magnetic reluctance of the excitation magnetic circuit decreases accordingly. Under the condition that the excitation voltage remains unchanged, the current in the excitation coil increases accordingly. Therefore, the difference in excitation current between adjacent cycles directly reflects the change in the magnetic circuit state caused by the change in air gap width during that time interval.

[0025] The controller determines the rate of change of magnetic flux density over time within the excitation circuit between the magnetic head end face and the target iron surface based on the excitation current difference between adjacent cycles and the excitation coil parameters pre-stored in the controller's internal memory. These parameters include the total number of turns of the excitation coil along the coil frame axis and the radial cross-sectional area of ​​the coil frame. Specifically, according to Ampere's circuital law, the magnetomotive force generated by the excitation coil is directly proportional to the product of the coil turns and the excitation current. The magnetic flux density of the magnetic circuit is directly proportional to the magnetomotive force and inversely proportional to the cross-sectional area of ​​the magnetic circuit. Between two adjacent detection cycles, the excitation voltage is kept constant by the controller, and the cross-sectional area of ​​the magnetic circuit is determined by and remains unchanged by the radial cross-sectional area of ​​the coil frame. Therefore, the change in excitation current uniquely reflects the change in magnetic reluctance, which is directly caused by the change in the air gap width between the magnetic head end face and the target iron surface. The controller multiplies the difference in excitation current between adjacent cycles by the number of coil turns, divides it by the radial cross-sectional area of ​​the coil frame, and then divides it by the time interval between adjacent detection cycles. The resulting quotient is used as the rate of change of magnetic flux density in the excitation magnetic circuit over time at the current moment, thus obtaining the magnetic flux density variation characteristics of the excitation magnetic circuit. Since a larger number of turns results in a greater change in magnetomotive force per unit current difference, and a larger cross-sectional area results in a smaller change in magnetic flux density per unit magnetic flux, a greater number of turns and a larger cross-sectional area result in a greater change in magnetic flux density for the same current change.

[0026] The controller determines the geometric angle between the magnetic head end face normal and the connecting rod axis based on the magnetic induction change characteristics of the excitation magnetic circuit, combined with the current deflection angle value read from the angle sensor built into the universal bending node, including the pitch angle determined by the ratio of the gravity vector output by the triaxial accelerometer in the angle sensor in the axial direction of the connecting rod to the components on the two orthogonal axes in the cross section, and the roll angle obtained by integrating the angular velocity by the gyroscope.

[0027] The geometric angle is determined as follows: an angle sensor is installed on the moving side of the ball joint structure at the universal bending node, and its measurement coordinate system rotates with the ball joint; the controller takes the current attitude quaternion or Euler angle output by the angle sensor, converts it to a reference coordinate system with the axis of the connecting rod's rear end (hand handle connection end) as the reference direction, and extracts the angle between the normal vector of the magnetic head end face and the axial vector of the connecting rod. This angle directly reflects the degree of inclination of the end face relative to the iron surface during the process of the magnetic head end face adhering to the iron surface. When this angle value does not exceed the preset angle near threshold (3 to 5 degrees in this embodiment), it indicates that the magnetic head end face is approximately perpendicular to the connecting rod axis, and the end face and the iron surface are in direct contact. At this time, the change in magnetic resistance in the excitation magnetic circuit is mainly caused by the overall synchronous reduction of the air gap between the end face and the iron surface. As the air gap decreases uniformly, the total magnetic resistance of the magnetic circuit decreases monotonically, the current in the excitation coil increases monotonically, and the direction of magnetic resistance change is unidirectionally decreasing. When the included angle value exceeds a preset angle threshold and the rate of change in the magnetic induction variation characteristics of the excitation magnetic circuit shows a difference exceeding a preset non-uniform judgment tolerance (15% to 20% of the average rate of change in each detection cycle in this embodiment) between different positions of the end face, it indicates that the end face of the magnetic chuck is tilted relative to the axis of the connecting rod. One side of the end face contacts the surface of the iron part first, while the other side still has a large air gap. At this time, the magnetic resistance change shows a non-uniform characteristic. The air gap on the first contact side has been greatly reduced, and the magnetic resistance of the corresponding magnetic circuit section on that side has dropped to a low level. However, the air gap on the suspended side remains at a large value, and the magnetic resistance of the corresponding magnetic circuit section on that side remains at a high level. Based on the comparison result of the included angle value and the angle approaching the threshold, and the difference in the rate of change value in the magnetic induction variation characteristics of the excitation magnetic circuit during each detection cycle, the controller determines whether the direction of the magnetic resistance change is unidirectional decrease or non-uniform distribution, and whether the magnitude of the magnetic resistance change is a large overall change or a small local change, thus obtaining the amount of magnetic resistance change when the magnetic chuck adheres to the surface of the target iron part.

[0028] After obtaining the change in magnetic resistance when the magnetic head adheres to the surface of the target iron piece, the controller performs the process of acquiring the initial spatial adhesion characteristics.

[0029] The controller determines the non-uniform distribution of the air gap width between each edge of the magnetic chuck end face and the surface of the target iron part based on the direction and amplitude of the magnetic reluctance change, thus obtaining the uniformity characteristics of the magnetic chuck end face fit. The specific determination method is as follows.

[0030] The controller divides the circular outline of the magnetic head end face into several azimuth sectors along the circumference, with the number of sectors ranging from 8 to 16. Each sector covers a central angle range of 22.5 to 45 degrees around the end face. For each azimuth sector, the controller takes the change in magnetic reluctance of the excitation magnetic circuit segment corresponding to the outer edge of the sector between two adjacent detection cycles as the local magnetic reluctance change value for that sector. The controller traverses all azimuth sectors and calculates the degree of difference between the local magnetic reluctance change values ​​of each sector.

[0031] If the direction of magnetoresistive change is unidirectional decreasing, meaning that the local magnetoresistive change values ​​of all sectors show a decreasing trend during adjacent detection cycles, and the maximum difference between the magnitudes of local magnetoresistive change values ​​of each sector does not exceed a preset unidirectional change threshold, then the controller determines that the air gap width at each edge position of the magnetic suction head end face is uniformly reduced. That is, the end face approaches the iron surface in a generally parallel manner, and the air gap width at each edge position decreases synchronously at a basically the same rate. This unidirectional change threshold is determined based on the statistical mean of the excitation current difference between adjacent cycles under the condition of full contact and contact between the magnetic suction head end face and the flat iron plate: under the condition of full contact and contact, since the gap between the end face and the iron plate surface is uniform at all points, there are only small fluctuations in the local magnetoresistive change values ​​corresponding to each sector due to the microscopic unevenness of the end face and the roughness of the iron plate surface. The statistical standard deviation of these small fluctuations is the normal difference range under the condition of uniform reduction of each sector. In this embodiment, the unidirectional change threshold is set to 1.2 to 1.5 times the statistical mean, in order to distinguish uniform bonding within the normal fluctuation range from tilted bonding outside the range.

[0032] If the direction of magnetoresistive change indicates a non-uniform distribution, meaning that the local magnetoresistive change values ​​of some sectors exhibit significantly different patterns from other sectors during adjacent detection cycles (e.g., some sectors show stable changes while others continue to decrease, or some sectors show a significantly larger decrease in value than others), the controller sorts the sectors according to the magnitude of the decrease in local magnetoresistive change values. The sector with the largest decrease in local magnetoresistive change value indicates that the air gap between the corresponding end-face edge and the iron surface is shrinking at the fastest rate, and is marked as the narrowest air gap, corresponding to the end-face edge region that first contacts or is closest to the iron surface. The sector with the smallest decrease in local magnetoresistive change value indicates that the air gap between the corresponding end-face edge and the iron surface is shrinking at the slowest rate or even remains unchanged, and is marked as the widest air gap, corresponding to the end-face edge region that last contacts or is farthest from the iron surface. For the remaining sectors between the sector with the largest and smallest reduction, their air gap widths are sorted according to the reduction ratio, ranging from the narrowest to the widest point of the air gap. Regarding the magnitude of the reluctance change, the controller determines the magnitude based on the dispersion of the reduction values ​​for each sector: if the reduction ratio between the sector with the largest and smallest reduction does not exceed a preset amplitude uniformity ratio threshold (1.5 to 2.0 in this embodiment), it is determined to be a small local change; if the ratio exceeds the amplitude uniformity ratio threshold, it is determined to be a large overall change. The controller combines the air gap width sorting results and the change magnitude determination results for each sector to obtain the uniformity characteristics of the magnetic head end face fit.

[0033] The controller determines the real-time orientation of the magnetic chuck end face in space by reading the deflection angle value from the angle sensor built into the universal bending node of the connecting rod, based on the direction of the line connecting the narrowest and widest air gap sectors in the uniformity of the magnetic chuck end face fit characteristics. Specifically, the controller constructs a polar coordinate system in the plane containing the end face, with the center of the magnetic chuck end face as the origin. The central angle direction of the sector where the air gap is narrowest is taken as the first reference direction, and the central angle direction of the sector where the air gap is widest is taken as the second reference direction. The line connecting the first and second reference directions is the tilt direction of the end face, pointing towards the transition direction from narrow to wide air gap, which is the direction in which the magnetic chuck end face tilts away from the surface of the iron part. The controller reads the deflection angle value from the angle sensor, including the pitch angle and roll angle with reference to the direction of gravity. The angle sensor outputs the relative deflection angle of the moving side of the universal bending node relative to the stationary side. The controller superimposes this relative deflection angle with the reference direction of the rear end of the connecting rod (the end of the hand handle) to obtain the orientation of the magnetic head end face in the absolute space coordinate system.

[0034] The reference direction is calibrated by the controller during device power-on initialization using the direction of gravity as a reference: when the operator holds the connecting rod vertically with the magnetic head end face horizontally downwards, the initial reading of the angle sensor is recorded as the zero-position reference. The controller integrates the end face tilt direction (azimuth angle in polar coordinates) with the end face spatial orientation (pitch and roll angles in absolute spatial coordinates): the end face tilt direction indicates the tilt direction of the end face in its own plane, and the spatial orientation indicates the overall attitude of the end face plane in space. The combination of the two can completely describe the orientation of the magnetic head end face in space and its tilt relationship with the iron surface, thus obtaining the spatial orientation characteristics of the magnetic head end face.

[0035] Based on the uniformity of the fit and the spatial orientation, the controller maps the air gap width distribution at each edge of the magnetic head end face to the corresponding contact area on the surface of the target iron piece, thus obtaining the initial spatial fit characteristics between the magnetic head end face and the contact surface of the target iron piece.

[0036] The specific mapping method is as follows: The controller uses the end-face normal vector in the spatial orientation feature of the magnetic chuck end face as the projection direction, and projects the spatial coordinates of the edge positions of each directional sector on the end face along the direction of this normal vector onto the plane where the target iron surface is located. The plane where the target iron surface is located is determined by the position and normal of the directional sector that the magnetic chuck end face first contacts the iron surface when the operator initially attaches it. After projection, each directional sector edge position on the end face corresponds to a projection point on the iron surface plane. The normal distance between this projection point and the corresponding edge position on the end face is the air gap width of that directional sector. The controller combines the air gap width values ​​of all directional sectors, the corresponding end-face edge position coordinates, and the projection point coordinates on the iron surface into a set of spatial mapping relationships. This set of spatial mapping relationships completely describes the three-dimensional distance distribution between each edge position of the magnetic chuck end face and the target iron surface, the overall tilt direction and tilt angle of the end face, and the boundary of the contact area between the end face and the iron surface, thus obtaining the initial spatial attachment features of the contact surface between the magnetic chuck end face and the target iron surface.

[0037] Step 3: Divide the space into categories After obtaining the initial spatial fit characteristics, the controller further classifies the edge magnetic leakage degree of the magnetic suction head for narrow gap operation conditions (such as the gap between steel bars in construction sites, the gap in steel structures, etc.).

[0038] The controller extracts edge segments with air gap widths exceeding the normal closure threshold of the excitation magnetic circuit based on the air gap widths at each edge position of the magnetic head end face in the initial spatial fitting characteristics, thus obtaining a set of edge leakage magnetic segments for narrow-slit conditions. The normal closure threshold of the excitation magnetic circuit is taken as 5% to 10% of the radius of the magnetic head end face. For example, when the end face radius is 50 mm, the threshold is taken as 2.5 to 5.0 mm. The physical basis for this threshold is that when the air gap width at the end face edge position does not exceed 5% to 10% of the end face radius, the magnetic resistance of the excitation magnetic flux diffusing outward from this edge position is much greater than the magnetic resistance of forming a closed loop through the iron part directly in front of the end face. This is because the edge leakage magnetic path passes through air with a permeability of about 1, while the closed magnetic circuit directly in front passes through iron material with a permeability of several thousand. Therefore, the shunting effect of this edge position on the total excitation magnetic flux is negligible and is considered as a normal magnetic circuit closure. When the air gap width of a certain edge segment exceeds the threshold, the magnetic reluctance of the edge leakage magnetic path at that segment drops to a level comparable to the closed magnetic circuit directly in front, and the excitation magnetic flux begins to leak outward from that segment, forming edge leakage magnetic flux. The controller traverses all edge positions on the end face of the magnetic suction head, merges adjacent edge positions with consecutive air gap widths exceeding the threshold into one edge segment, and records the starting angle, ending angle, and arc length of each edge segment in the circumferential direction of the end face, thus obtaining a set of edge leakage magnetic flux segments for narrow slot conditions.

[0039] The controller determines the proportion of magnetic flux leaking outward through the edge air gap in the magnetic flux leakage zone of the magnetic head excitation circuit to the total excitation magnetic flux based on the arc length and average air gap width of each edge segment in the narrow-slit condition edge magnetic flux leakage zone set, thus obtaining the edge magnetic flux leakage degree value for the narrow-slit condition. Specifically, for each edge magnetic flux leakage zone in the set, the controller takes the arithmetic mean of the air gap widths at each edge position within that zone as the average air gap width of that zone. With the end face diameter and excitation ampere-turns remaining constant, a larger average air gap width indicates a larger equivalent magnetic reluctance of the edge magnetic flux leakage path in that zone, because the leakage flux must traverse a longer air path to reach the surface of the iron part from the end face, resulting in a smaller leakage flux per unit arc length. Simultaneously, a longer arc length results in a larger cumulative leakage flux area in that zone, and a larger total leakage flux leaking through that zone. The controller determines the ratio of the arc length to the average air gap width of each edge leakage magnetic field segment. This ratio reflects the total magnetic permeability of the leakage magnetic field path in that segment. Combined with the total excitation magnetic flux (determined by the excitation ampere-turns and the total magnetic reluctance of the magnetic circuit), the controller determines the proportion of the sum of magnetic flux leaking through each edge segment to the total excitation magnetic flux, based on the proportion of the magnetic permeability of the leakage magnetic field path in each segment to the total magnetic permeability of the parallel magnetic circuit. This yields the edge leakage magnetic field degree value for the narrow gap condition. The value of this degree value is a dimensionless ratio between 0 and 1: a value of 0 indicates no edge leakage magnetic field, and all excitation magnetic flux passes through the iron part directly in front of the end face to form a closed loop; a value close to 1 indicates that edge leakage magnetic field dominates, and the excitation magnetic flux inside the iron part has significantly attenuated.

[0040] The controller categorizes the spatial contact state between the magnetic head end face and the target iron part into three types based on the preset magnetic leakage degree range where the edge magnetic leakage value falls under the narrow slit condition. The upper limits of the first and second preset intervals are obtained through actual measurement and calibration of the adsorption force of iron parts of different specifications under different contact postures. Using the rated adsorption force generated when the magnetic head end face is in full contact as a benchmark, the rated adsorption force is determined by the end face diameter, excitation ampere-turns, and the magnetic permeability of the iron part material. Calibration was performed under laboratory conditions with the end face fully in contact with a flat iron plate with a surface roughness Ra ≤ 3.2 micrometers. The magnetic leakage degree value corresponding to the decrease in measured adsorption force to 90% of the rated adsorption force due to edge magnetic leakage is taken as the upper limit of the first preset interval, and the magnetic leakage degree value corresponding to the decrease in measured adsorption force to 70% of the rated adsorption force is taken as the upper limit of the second preset interval. The correspondence between the decrease in adsorption force and the degree of magnetic leakage is determined through the following calibration experiment: Non-magnetic pads of different thicknesses were inserted between the end face of the magnetic head and the iron plate to simulate edge air gaps of different sizes. The magnetic leakage degree and the corresponding measured adsorption force were recorded for each pad thickness. A calibration curve of magnetic leakage degree and adsorption force was established. The horizontal axis values ​​of magnetic leakage degree when the adsorption force is 90% and 70% of the rated value were read from the curve as the upper limits of the two intervals.

[0041] When the magnetic leakage value at the edge of the narrow slit is lower than the upper limit of the first preset range, the controller classifies the spatial contact state as full contact contact. At this time, the proportion of the excitation flux leaking outward through the edge air gap is very low, and most of the magnetic flux passes through the iron part to form an effective magnetic attraction circuit. Apart from the sub-millimeter-level non-contact gap caused by the micro-unevenness of the end face and the roughness of the iron part surface, there is no visible air gap between the end face and the iron part surface. The magnetization inside the iron part is uniform and sufficient, and the attraction force is close to the rated value.

[0042] When the magnetic leakage value at the edge of the narrow gap is not lower than the upper limit of the first preset interval and does not exceed the upper limit of the second preset interval, the controller classifies the spatial bonding state as local edge floating bonding. At this time, there is a significant air gap on one side or in a certain local area of ​​the magnetic head end face. The magnetic leakage of the corresponding edge leakage section accounts for a certain proportion of the total excitation magnetic flux, resulting in a decrease in the effective magnetic flux entering the iron part. The magnetization is sufficient on the bonding side (narrow air gap side) inside the iron part, while the magnetization is weaker on the floating side (wide air gap side), forming a spatial gradient of magnetization intensity inside the iron part, and the attraction force shows a perceptible decrease compared to the rated value.

[0043] When the magnetic leakage value at the edge of the narrow gap exceeds the upper limit of the second preset range, the controller classifies the spatial bonding state into large gap suspended bonding. At this time, the air gap width of most edge sections of the magnetic head end face exceeds the normal closing threshold. The main path of the excitation magnetic flux has changed from passing through the iron part directly in front of the end face to forming a local closed loop in the air through the air gap at the edge of the end face. Only a small amount of magnetic flux enters the iron part. The magnetization inside the iron part is very low, and the attraction force drops significantly to less than half of the rated value. The iron part is at risk of slipping off the magnetic head end face under its own weight or external force.

[0044] Step 4: Accumulate the demagnetizing pulse width After obtaining the spatial fit category, the controller adaptively determines the width parameter of the demagnetizing pulse based on the difference in fit category, so as to match different demagnetizing energies for different residual magnetism distribution states inside iron parts.

[0045] Based on the spatial bonding category, the controller retrieves the corresponding demagnetization holding period duration and initial segmented pulse width from the bonding category-demagnetization strategy mapping table pre-stored in the controller's internal non-volatile memory (such as EEPROM or Flash), thus obtaining the demagnetization strategy parameter set. The contents of the bonding category-demagnetization strategy mapping table are as follows: the demagnetization holding period duration for full-contact bonding is 0.5 to 1.0 seconds, and the initial segmented pulse width is 100 to 200 microseconds; the demagnetization holding period duration for partial edge floating bonding is 1.0 to 2.0 seconds, and the initial segmented pulse width is 200 to 350 microseconds; the demagnetization holding period duration for large-gap suspended bonding is 2.0 to 3.0 seconds, and the initial segmented pulse width is 350 to 500 microseconds.

[0046] The physical basis of this mapping relationship is explained below. During full-contact bonding, the magnetic circuit is well-closed. During the excitation phase, the magnetic flux entering the iron part is large and evenly distributed. The remanent magnetism inside the iron part is mainly concentrated on the surface layer (within the skin depth range), and the remanent magnetic domains are shallow and relatively ordered. During demagnetization, the reverse magnetic field only needs to act on the surface layer of the iron part to complete the domain flipping, requiring a short demagnetization holding time and low single-pulse energy. During partial edge-free bonding, the air gap on one side of the end face is large while the air gap on the other side is small. The magnetic flux entering the iron part exhibits a spatial gradient distribution. The iron part area corresponding to the narrower air gap side is more deeply magnetized, while the iron part area corresponding to the wider air gap side is less magnetized. During demagnetization, the reverse magnetic field needs to penetrate to a deeper region inside the iron part within the demagnetization holding time to flip the deep magnetic domains. It also needs to cover the additional demagnetization energy required to cover the deeply magnetized region on the narrower air gap side. Therefore, both the demagnetization holding time and pulse energy must be greater than those required for full-contact bonding. When the gap is large and the iron parts are suspended, although the total amount of magnetic flux entering the iron parts is small and the overall magnetization of the iron parts is low, in narrow gap spaces (such as between densely arranged steel bars on construction sites), the adjacent steel structures are induced by the leakage magnetic field at the edge of the magnetic head during the excitation stage, resulting in secondary magnetization. This secondary magnetization magnetic field acts in the opposite direction on a local area of ​​the iron parts surface, forming a local orientation magnetization layer near the surface of the iron parts with a direction different from the main magnetization direction. Although the depth of this orientation magnetization layer is limited, the magnetic domain arrangement direction is not completely aligned with the direction of the main demagnetization magnetic field. A longer demagnetization holding time and stronger pulse energy are required to ensure that the magnetic domains in this orientation magnetization layer are also effectively flipped.

[0047] The controller divides the demagnetization holding period into multiple equal-length sub-periods based on the demagnetization strategy parameter group's demagnetization holding period duration and initial segmented pulse width. The number of sub-periods is determined as follows: The controller reads the pre-stored minimum resolution of a single pulse output from the pulse generator, i.e., the minimum conduction time of the power switch in the H-bridge drive circuit, which is determined by the switching speed of the switch and the gate charging / discharging time constant of the drive circuit; in this embodiment, it is taken as 10 to 20 microseconds. The total duration of the demagnetization holding period is divided by the minimum resolution of a single pulse, and the quotient is the maximum number of sub-periods that can be divided. The controller selects 8 to 16 from this maximum number as the actual number of sub-periods. Within each sub-period, the controller allocates the initial segmented pulse width as the demagnetization pulse width for that sub-period, i.e., the duration of the forward conduction of the pulse generator's H-bridge circuit (the direction of the demagnetization current is opposite to that of the excitation phase) within that sub-period. The controller accumulates the demagnetizing pulse width segment by segment in ascending order of sub-segment number: the first sub-segment accumulates to obtain the first cumulative demagnetizing pulse width, the second sub-segment accumulates to obtain the second cumulative demagnetizing pulse width, and so on until the last sub-segment, obtaining the initial total demagnetizing pulse width. This segment-by-segment accumulation ensures that the total energy of the demagnetizing pulse is released evenly during the demagnetizing hold period, avoiding coil overheating and magnetic saturation of the iron components caused by a single long pulse.

[0048] The controller applies a width compensation to the initial total demagnetizing pulse width based on the total width of the initial demagnetizing pulse and the average air gap width of each edge segment in the set of leakage flux leakage segments in the narrow gap condition obtained in step 3, thus obtaining the compensated total demagnetizing pulse width value. When the average air gap width of each edge leakage magnetic section is small (e.g., not exceeding 15% of the end face radius), the magnetic head end face fits well with the iron surface, the iron is sufficiently and uniformly magnetized, the main orientation of the magnetic domains is consistent with the main magnetization direction, and the total width of the initial demagnetizing pulse can cover the residual magnetism elimination requirement inside the iron. The width compensation is 5% to 10% of the total width of the initial demagnetizing pulse to compensate for the current attenuation caused by the heating of the coil resistance during demagnetization. When the average air gap width of each edge leakage magnetic section is large (e.g., exceeding 15% of the end face radius), although the overall magnetization of the iron is low, the leakage magnetic flux at the edge leakage magnetic section forms a local closed magnetic loop when passing through the near surface of the iron. This local closed magnetic loop generates a unidirectional residual magnetic component in the local area near the near surface of the iron, which is at a certain angle to the main magnetization direction (determined by the incident direction of the leakage magnetic flux entering the iron from the edge of the end face). The domain alignment of the unidirectional remanent magnetic component is not perfectly aligned with the direction of the main demagnetizing magnetic field. During demagnetization, the reversal efficiency of the main demagnetizing magnetic field on this tilted domain is lower than that on the positive domain. Therefore, an additional demagnetizing pulse width is required to provide sufficient magnetic field energy to overcome the magnetic anisotropy barrier of the tilted domain. Furthermore, the secondary orientation magnetization layer formed near the surface of the iron component due to induction magnetization by the surrounding steel structure within the narrow gap also requires additional demagnetizing energy. Therefore, when the average air gap width is large, the width compensation is taken as 15% to 30% of the total width of the initial demagnetizing pulse. The upper limit of this compensation (30%) is based on the following: after demagnetizing experiments, for a magnetic chuck with an end face diameter of 80 to 120 mm, when suspended and bonded to a non-flat iron surface with a large gap, the additional demagnetizing energy required for domain reversal of the unidirectional remanent magnetic component near the iron surface does not exceed 30% of the demagnetizing energy under full-bonding conditions. When the average air gap width of the controller is between 15% and 100% of the end face radius, the specific compensation ratio is determined by linear interpolation between 5% and 15% (lower compensation limit range) and 15% and 30% (upper compensation limit range) to obtain the total width value of the demagnetizing pulse after compensation.

[0049] Step 5: Generate pulse demagnetization control command After obtaining the compensated total width value of the demagnetizing pulse, the controller converts it into a demagnetizing control command that contains precise timing parameters and current direction control information, which can be directly executed by the pulse generator.

[0050] The controller, based on the compensated total width of the demagnetizing pulse and referring to the maximum duration limit of a single pulse output from the pulse generator within the mounting bracket, divides the compensated total width of the demagnetizing pulse into multiple pulse output cycles. The maximum duration limit of a single pulse from the pulse generator is determined by the junction temperature rise limit of the power switching devices (such as MOSFETs or IGBTs) in the H-bridge drive circuit: When the power switching transistor is in the on-state, it has an on-resistance; the on-current flowing through this resistance generates Joule heat. If the on-time is too long, the junction temperature of the switching transistor will exceed its maximum allowable junction temperature (typically 150 to 175 degrees Celsius), leading to thermal breakdown failure. In this embodiment, the on-resistance of the switching transistor is taken as 10 to 50 milliohms, and the peak on-current is taken as the rated current of the excitation coil as 3 to 5 amperes. Based on the thermal resistance parameters of the switching transistor (junction-to-ambient thermal resistance of 40 to 60 degrees Celsius per watt) and the maximum allowable junction temperature rise (100 to 125 degrees Celsius), the maximum duration limit of a single pulse is calculated to be 2 to 5 milliseconds. The controller divides the total width of the compensated demagnetizing pulse by the maximum duration of a single pulse: if the quotient is less than or equal to 1, the demagnetizing pulse can be completed within a single pulse output cycle, with a split count of 1; if the quotient is greater than 1, it is rounded up to obtain the required number of pulse output cycles. Within each pulse output cycle, the forward conduction period width is equal to the total width of the compensated demagnetizing pulse divided by the number of pulse output cycles. If the division is not exact, the conduction width of the last cycle is taken as the remainder, and the remaining cycles are taken as the integer part of the average. The reverse turn-off period width is 0.3 to 0.5 times the forward conduction period width. This turn-off period is used to provide a current freewheeling path for the freewheeling diodes in the H-bridge circuit, allowing the magnetic field energy stored in the excitation coil during forward conduction to be released through the freewheeling circuit. At the same time, it reserves dead time for the switching transistor for the next current polarity reversal (to prevent the upper and lower bridge arms from conducting simultaneously and causing a power supply short circuit; the dead time is 1 to 5 microseconds). The controller combines the number of pulse output cycles, the sequence number of each cycle, the forward conduction time width, and the reverse turn-off time width into a demagnetizing pulse timing parameter group.

[0051] The controller generates pulse demagnetization control commands based on the demagnetization pulse timing parameter set, combined with the drive current polarity configuration parameters and drive current amplitude upper limit parameters pre-stored in the controller memory between the pulse generator output and the magnetic head excitation coil. The drive current polarity configuration parameters include: a switch combination code for forward conduction where the upper left and lower right arms of the H-bridge are on, and the rest are off; a switch combination code for reverse conduction where the upper right and lower left arms of the H-bridge are on, and the rest are off; and a switch combination code for when all are off (high resistance state). The upper limit of the drive current amplitude is set to the rated current value of the excitation coil (determined by the wire diameter and insulation class of the coil enameled wire, taken as 3 to 5 amperes in this embodiment) to prevent overheating of the coil leading to insulation aging and breakdown. The controller encodes each parameter in the demagnetizing pulse timing parameter group into a control command sequence recognizable by the pulse generator in binary format. Each command includes: pulse cycle number (4 bits, supporting up to 16 cycles), the forward conduction width of the cycle (in units of the pulse generator clock cycle, with clock frequencies ranging from 1 to 10 MHz, and one clock cycle corresponding to a time resolution of 0.1 to 1 microsecond), the turn-off width of the cycle (also in units of clock cycles), and a current polarity reversal flag (1 bit: 0 indicates the same direction as the previous cycle, 1 indicates the reversal direction). The encoded pulse demagnetizing control command sequence is transmitted between the controller and the pulse generator via SPI or I / O. 2 The C serial communication interface sends the command to the instruction buffer register inside the pulse generator, waiting for the execution trigger signal.

[0052] Step 6: Perform pulse demagnetization and determine the state of residual magnetism elimination. After the controller generates a pulse demagnetization control command and loads it into the instruction buffer register of the pulse generator, it initiates the demagnetization sequence by sending an execution trigger signal (a rising edge pulse) to the pulse generator.

[0053] After receiving the execution trigger signal, the pulse generator executes each pulse output cycle sequentially according to the cycle number in the instruction sequence. For each pulse output cycle, the pulse generator determines the switching combination code of the H-bridge circuit for that cycle based on the current polarity reversal flag: if the current polarity reversal flag is inverted, the switching combination code is reversed compared to the previous cycle (i.e., the forward-conducting and reverse-conducting bridge arms are interchanged), making the current direction flowing through the excitation coil opposite to that of the previous cycle; if the current polarity reversal flag is in the same direction, the switching combination code of the previous cycle remains unchanged. During the forward conduction period, the pulse generator drives the corresponding switch transistor of the H-bridge to conduct according to the set switching combination code, applying the DC voltage of the battery to both ends of the excitation coil, generating a reverse demagnetizing current in the coil. The direction of the current is opposite to that of the excitation phase, and the rate of rise is determined by the coil inductance and the battery voltage. The demagnetizing magnetic field established by the demagnetizing current in the coil is in the opposite direction to the attraction magnetic field during the excitation phase. This reverse magnetic field exits at the end face of the magnetic attractor and is applied to the surface of the target iron part, canceling out the direction of the residual magnetic field inside the iron part. During the forward conduction period of each pulse output cycle, the demagnetizing magnetic field applies a magnetic torque opposite to the direction of residual magnetism to the magnetic domains inside the iron part, driving the magnetic moment vector of the magnetic domains to rotate from the direction of residual magnetism to the direction of the demagnetizing magnetic field. During the reverse turn-off period, all the H-bridge switches are turned off, and the coil current forms a freewheeling circuit through the freewheeling diode. The current gradually decays to zero, and the magnetic domains inside the iron part that were flipped during the forward conduction process tend to stabilize in the new direction.

[0054] Through alternating forward demagnetization and current cut-off across all pulse output cycles, the magnetic domains inside the iron component undergo multiple flips under the influence of the alternating demagnetizing magnetic field. Each flip consumes a portion of the magnetic anisotropy of the domains, causing the magnetic moment vector directions to become increasingly random and disordered. Macroscopically, the remanent magnetization vectors of various micro-regions within the iron component no longer align, and their vector sum approaches zero, gradually decaying the macroscopic remanent magnetization of the iron component to near zero. This process is similar to applying a demagnetizing current with gradually decreasing amplitude and alternating direction to a ferromagnetic material to achieve alternating current demagnetization.

[0055] After the reverse turn-off period of the last pulse output cycle specified in the instruction sequence ends, the entire demagnetizing pulse sequence is completed. The controller waits for a short settling time (10 to 20 milliseconds, which is 5 to 10 times the electrical resonant period determined by the inductance of the excitation coil and the equivalent parallel capacitance of the coil, ensuring that the transient oscillation voltage across the coil has decayed below the steady-state noise level). The controller's analog-to-digital converter is activated to sample the voltage across the sampling resistor connected in series with the excitation coil. Since there is no driving current in the excitation coil after the demagnetizing pulse sequence, the voltage measured across the sampling resistor is solely derived from the voltage induced in the excitation coil by the residual magnetism inside the iron component. The controller continuously collects 100 to 200 sampling points at a sampling rate of not less than 1 kHz, and takes the root mean square of the sampled values ​​as the effective value of the residual induced voltage of the coil after demagnetization. The amplitude of this residual induced voltage is proportional to the magnetic induction intensity of the residual magnetism inside the iron component, and the proportionality coefficient is jointly determined by the number of turns of the excitation coil, the cross-sectional area of ​​the coil, and the width of the residual air gap between the iron component and the end face of the magnetic chuck.

[0056] The controller compares the residual induced voltage of the demagnetizing coil with the residual magnetism elimination judgment voltage threshold pre-stored in the controller's memory. The residual magnetism elimination judgment voltage threshold is calibrated by measuring the correspondence between the residual induced voltage and the actual residual attraction force of the iron parts after demagnetizing various specifications of iron parts (including different materials such as ordinary carbon steel, alloy steel, cast iron, and iron plates of different thicknesses, such as 5 mm to 50 mm) under different initial magnetization levels. When the residual induced voltage is between 50 and 100 millivolts, the residual attraction force generated by the residual magnetism on the iron part surface has decreased to less than one-tenth of the iron part's own weight. Below this level, the iron part can detach from the magnetic head end face under gravity or only requires slight external force. If the residual induced voltage of the coil after demagnetization is lower than this threshold, the controller determines that the residual magnetism has been eliminated, obtaining a positive result for residual magnetism elimination. If the residual induced voltage of the coil after demagnetization is still higher than the threshold, it indicates that demagnetization is insufficient, and there is still residual attraction force inside the iron part sufficient to prevent detachment. The controller records the number of demagnetization cycles executed so far (initially 1). Based on the ratio of the residual induced voltage value after the first demagnetization to a threshold, the number of additional demagnetization cycles is determined: if the ratio is less than 1.5, it indicates that the residual magnetism is only slightly above the threshold, the domain flipping is basically complete but a few stubborn domains remain, and one additional demagnetization cycle is sufficient; if the ratio is between 1.5 and 3, it indicates that a significant proportion of domains have not completed flipping, and two additional demagnetization cycles are needed to provide more flipping opportunities; if the ratio exceeds 3, it indicates that most domains still maintain their original residual magnetism direction, and three additional demagnetization cycles are needed. For each additional demagnetization cycle, the controller increases the total width of the compensated demagnetization pulse by 10% to 20% compared to the previous cycle. The increase is positively correlated with the residual voltage ratio: the closer the ratio is to the upper limit of the range, the larger the percentage increase. The controller then regenerates the demagnetization pulse timing parameter set and pulse demagnetization control command, executes the demagnetization process again, and re-acquires the residual induced voltage of the coil after demagnetization for comparison. This cycle can be performed a maximum of 3 times. If the residual induced voltage is still higher than the threshold after 3 additions, the controller will issue a demagnetization failure warning signal through the intelligent early warning module (the buzzer will sound a continuous 2-second beep, and the LED indicator will operate in a solid yellow light mode), prompting the operator to intervene manually. Under normal operating conditions, most iron parts can achieve the residual magnetism elimination condition after the first demagnetization or at most one additional demagnetization, thus obtaining the residual magnetism elimination state on the surface of the target iron part.

[0057] Step 7: Adjust the extension length of the connecting rod After confirming that the residual magnetism has been eliminated, the controller adjusts the extension length of the electric connecting rod so that the end face of the magnetic suction head is safely away from the close working area of ​​the target iron surface, providing space for subsequent device movement or the next adsorption operation.

[0058] After receiving a positive result indicating the removal of residual magnetism, the controller executes the magnetic attraction release confirmation process. The controller sends an excitation shutdown lockout signal to the pulse generator within the mounting base via the control interface. This signal is a specific coded GPIO level sequence (e.g., pulling the pulse generator's enable pin low and simultaneously setting the gate drive signals of all H-bridge switches to low), causing all four switches (two upper bridge arms and two lower bridge arms) of the pulse generator's H-bridge circuit to simultaneously be in a high-impedance shutdown state. After the H-bridge is completely shut down, all current paths between the two terminals of the excitation coil and the battery positive terminal and ground are cut off. That is, the coil is neither connected to the battery positive terminal through the upper bridge arm switches nor to ground through the lower bridge arm switches. There is no drive current in the coil, and only a weak residual induced voltage remains at the coil ends after demagnetization. At this point, no excitation magnetic field is generated at the end face of the magnetic suction head, and the electromagnetic attraction force of the magnetic suction head on the target iron piece is completely released. After sending the excitation shutdown lockout signal, the controller waits for 5 to 10 milliseconds, which is sufficient time for the remaining magnetic field energy in the coil to dissipate naturally through the equivalent parallel resistance inside the coil. Then, it reads the tensile load value currently output by the load sensor as the reference load after the magnetic attraction is released. This reference load is compared with the adsorption state load recorded during the excitation phase: if the reference load has decreased by more than 50% compared to the adsorption state load, it is confirmed that the magnetic attraction has been effectively released; if the load has decreased by less than 50%, there may be a situation where the iron part has not been completely released. The controller re-executes a short (0.2 to 0.3 seconds) additional demagnetizing pulse and repeats this confirmation step to obtain the magnetic attraction release confirmation status.

[0059] After confirming the magnetic attraction force release, the controller reads the real-time tensile load value along the connecting rod axis detected by the built-in overload sensor in the handgrip. The overload sensor is a strain gauge type tension sensor; its internal metallic elastomer generates micro-strain when subjected to axial tensile force. The resistance value of the strain gauge attached to the surface of the elastomer changes proportionally. This resistance change is converted into a differential voltage signal via a Wheatstone bridge, amplified by an instrumentation amplifier, and then converted into a digital load value by an analog-to-digital converter. The controller compares the real-time tensile load value with a preset overload threshold. The overload threshold is set to 1.5 to 2 times the device's own weight. The device's own weight includes the sum of the gravity of the magnetic head, mounting base, electric connecting rod, and handgrip, calculated from the density and geometric volume integral of the 3D printed material of each component, and confirmed by actual weighing calibration after assembly. For example, if the device's own weight is 30 Newtons, the overload threshold is set to 45 to 60 Newtons. The lower threshold (1.5 times its own weight) is used to cover the additional gravity of residual iron filings or debris on the end face, and the upper threshold (2 times its own weight) is used to cover the gravity of thin, small iron parts that may still be attracted. If the real-time tensile load value exceeds the overload judgment threshold, it indicates that the connecting rod may still be carrying a heavy object, or the iron part has not been completely released, or large magnetic debris is attached to the end face of the magnetic head, or the iron part is stuck by the adjacent structure in the narrow space after demagnetization and cannot fall freely. The controller judges the bearing state of the connecting rod as an overload state. At this time, the controller does not send a retraction command to the telescopic drive motor to prevent the heavy object from falling out of control or damaging the screw nut transmission mechanism when the connecting rod is retracted under the condition of carrying a heavy object. The controller also issues an overload warning signal through the intelligent warning module (the buzzer sounds twice per second and the LED indicator flashes yellow) to prompt the operator to check the condition of the end face of the magnetic head.

[0060] When the controller determines that the connecting rod is not overloaded (the real-time tensile load value does not exceed the lower limit of the overload threshold), it sends a retraction command to the telescopic drive motor built into the electric connecting rod. The controller applies a DC voltage with polarity that reverses the motor's direction to the telescopic drive motor via the motor drive interface, which is an H-bridge motor drive circuit. This circuit is similar in structure to but independent of the H-bridge circuit of the pulse generator. The motor rotor rotates counterclockwise (forward rotation corresponds to connecting rod extension, and reverse rotation corresponds to connecting rod retraction). The motor's rotational motion is reduced in speed and increased in torque by a reduction gearbox before being transmitted to the lead screw and nut mechanism: the lead screw is coaxially connected to the motor output shaft, the external thread of the lead screw meshes with the internal thread of the nut, and the nut is fixedly connected to the sliding sleeve of the connecting rod. When the lead screw rotates under the motor's drive, the nut translates along the lead screw axis, causing the fixed sleeve to slide axially, thereby changing the total length of the connecting rod.

[0061] The retraction length is adaptively adjusted according to the spatial bonding category determined in step 3: When bonding in full contact, the original air gap between the magnetic head end face and the iron surface is extremely small. The retraction length is 0.6 to 1 times the diameter of the magnetic head end face, so that the end face is a small safe distance away from the iron surface to avoid scratching the end face and the iron surface when moving the device; When bonding with partial edge lifting, the end face is originally tilted, and there is already a certain gap between the lifting side and the iron surface, but the bonding side is still relatively close to the iron surface. The retraction length is 1 to 1.5 times the diameter of the magnetic head end face to ensure that the bonding side also gets a sufficient safe gap; When bonding with large gap suspension, there is already a large distance between the end face and the iron surface, but the end face may be located deep in the narrow gap. The retraction length is 1.5 to 2.2 times the diameter of the magnetic head end face, so that the magnetic head end face completely exits the narrow gap working area and returns to the open space.

[0062] The reason for using the end face diameter as the reference parameter for the retraction length is that the end face diameter determines the spatial size of the magnetic head and the effective range of the magnetic field. The larger the end face diameter, the farther the magnetic field inductively couples with the surrounding iron parts. After retraction, a larger safety distance is needed to prevent the residual weak magnetic field from accidentally attracting adjacent iron parts in the narrow space. The controller monitors the number of rotations of the motor in real time through the rotary encoder (such as a Hall sensor or photoelectric encoder) built into the telescopic drive motor. Based on the lead screw pitch and reduction ratio, it calculates the actual retraction length of the connecting rod. When the actual retraction length reaches the target retraction length, the motor drive stops, completing the retraction action. After the electric connecting rod retracts, the end face of the magnetic head reaches the space clearance position.

[0063] Step 8: Fall Risk Assessment After the magnetic head reaches the space avoidance position, the controller triggers the intelligent early warning module integrated at the reserved anti-fall hanging point of the mounting base to quantitatively assess the fall risk of the connecting rod assembly under the current spatial posture and load state.

[0064] The controller calculates the center of gravity of the assembly of the connecting rod and the mounting base based on the current extension length of the electric connecting rod in the space avoidance position of the magnetic head, and the real-time pose of the mounting base in space obtained by the angle sensor built into the universal bending node. The calculation process is performed in two stages.

[0065] The first level is component-level center of gravity calculation. The controller's internal memory pre-stores the mass, geometric dimensions, and center of gravity position (represented in the component's own local coordinate system) of each independent component. These parameters are obtained through analysis of the 3D CAD models of each component after the device is assembled, and are written into the controller's memory after actual weighing verification. Components include: magnetic head (including coil frame and excitation coil), mounting base (including pulse generator and anti-fall hanging point), sleeves of each section of electric connecting rod (the actual center of gravity position of each section is calculated according to the current extension length), telescopic drive motor, universal bending node ball joint structure, angle sensor, and hand handle (including battery, controller circuit board, and overload sensor).

[0066] The second stage involves the synthesis of the combined center of gravity. The controller takes the position of the fall arrestor attachment point in the absolute space coordinate system as the reference origin. Based on the current pitch and roll angles output by the angle sensors, the pitch angle is obtained from the gravity vector decomposition of the three-axis accelerometer, and the roll angle is obtained from the angular velocity integration of the gyroscope and after long-term fusion correction of the accelerometer data to determine the pose of the mount in absolute space (i.e., the rotation matrix and translation vector of the mount's local coordinate system relative to the gravity coordinate system).

[0067] The controller transmits the rotation matrix and translation vector step by step along each section of the connecting rod: from the mounting base to the front end of the universal bending node (the section before the moving side), through the current deflection angle of the ball joint to update the rotation matrix, then to the rear end of the universal bending node (the section after the moving side), and finally to the hand handle. During each stage of transmission, the controller multiplies the rotation matrix of the previous stage by the relative rotation matrix of the current stage (for the universal bending node, this is the three-degree-of-freedom rotation matrix of its ball joint; for the linear telescopic sleeve section, it is the identity matrix, since there is no relative rotation between sleeve sections), and adds the translation vector of the previous stage to the relative translation vector of the current stage (the length along the sleeve section's axial direction) to obtain the pose of the current stage component in the absolute space coordinate system. The controller transforms the local center-of-gravity coordinates of each component to the absolute space coordinate system using the absolute rotation matrix and translation vector of its stage, then performs a weighted average based on the mass of each component, multiplies the mass of each component by its absolute center-of-gravity coordinates, sums the results, and divides by the total mass to obtain the absolute center-of-gravity coordinates of the assembly.

[0068] The controller calculates the vertical (opposite direction of gravity) offset of the assembly's center of gravity relative to the fall arrest point: the Euclidean distance between the horizontal projection coordinates of the assembly's absolute center of gravity and the horizontal projection coordinates of the fall arrest point is taken as the center of gravity offset distance. When the center of gravity is directly below the fall arrest point (i.e., the horizontal projection of the center of gravity coincides with the horizontal projection of the arrest point), the offset distance is zero, the connecting rod assembly is in static equilibrium, and the fall arrest point only bears a downward vertical tension. When the center of gravity deviates from the horizontal projection of the fall arrest point, the offset distance is greater than zero, and gravity generates a torque on the fall arrest point that causes the assembly to rotate around the arrest point.

[0069] The controller uses the center of gravity offset distance in the combined weight center offset characteristics, combined with the real-time tensile load value collected by the overload sensor built into the hand handle after the electric connecting rod retracts. This load value is equal to the total weight of the device after retraction (because the iron parts have been released). It is used to verify the accuracy of the calculated total mass of the combined body and to calculate the overturning moment borne by the anti-fall attachment point.

[0070] The overturning moment is determined by the following relationship: the real-time tensile load value (along the connecting rod axis, this force is transmitted to the anti-fall point through the mounting base) multiplied by the horizontal component of the center of gravity offset distance in the direction perpendicular to the axial direction. The meaning of this overturning moment is: the magnitude of the moment generated by the axial tension of the connecting rod on the anti-fall point, causing the assembly to overturn around the point in the vertical plane.

[0071] The controller compares the calculated overturning moment value of the fall arrest point with the fall risk overturning moment threshold pre-stored in the non-volatile memory of the intelligent early warning module's microprocessor.

[0072] The fall risk overturning moment threshold is determined by the following method: Using the shear strength of the fall arrestor point (a through-hole penetrating the sidewall of the mounting base) as a constraint, the shear strength of the through-hole material is determined by the interlaminar shear strength of 3D-printed glass fiber reinforced nylon or carbon fiber reinforced polycarbonate (typically 30 to 50 MPa) and the effective shear-bearing cross-sectional area of ​​the through-hole (through-hole diameter multiplied by wall thickness). This product is then divided by a safety factor (2.0 to 3.0 to cover uncertainties in dynamic loads and material fatigue) to obtain the allowable bearing moment of the fall arrestor point. Simultaneously, the overturning resistance of the connecting rod assembly is used as a constraint. This overturning resistance is determined by the locking friction torque of the universal bending node ball joint (determined by the ball joint's preload and friction coefficient) and the fit clearance between the telescopic sleeve sections (excessive clearance generates additional bending moments between the sleeve sections). The smaller of these two values ​​is taken as the fall risk overturning moment threshold. In this embodiment, considering the above constraints, the overturning moment threshold for fall risk is set to 3 to 8 Newton-meters. The specific value is determined according to the linear relationship between the maximum extension length of the connecting rod and the total weight of the device: the larger the extension length and the larger the total weight of the device, the larger value within the threshold range is taken; when the extension length and the total weight of the device are small, the smaller value within the threshold range is taken.

[0073] If the overturning moment value of the fall arrestor attachment point exceeds the fall risk overturning moment threshold, the controller determines that the connecting rod assembly has a high risk of falling under its current position and load condition. It then generates a high-risk fall warning signal containing the risk level and overturning moment value, and sends the warning signal to the microprocessor of the intelligent warning module via the UART serial interface. Upon receiving the warning signal, the microprocessor of the intelligent warning module controls the buzzer drive circuit to generate a square wave signal at a preset frequency (e.g., 2 kHz to 4 kHz) and duty cycle (e.g., 50%) to drive the buzzer to emit an intermittent high-frequency beeping sound. The interval is alternating between 0.5 seconds of beeping followed by 0.5 seconds of silence. Simultaneously, it controls the LED drive circuit to make the LED indicator work in a red flashing mode (flashing frequency 2 to 4 Hz, duty cycle 50%). The controller also determines the fall risk probability level based on the difference between the overturning moment value and the fall risk overturning moment threshold: when the difference is within the range of 0 to 20% of the threshold, it indicates that the overturning moment is close to but has not significantly exceeded the safety boundary, and the assembly can be restored to a safe state after the operator slightly adjusts the grip posture, which is judged as low risk; when the difference is within the range of 20% to 50% of the threshold, it indicates that the overturning moment has significantly exceeded the safety boundary, and there is a moderate possibility that the assembly will overturn and fall under normal operating vibration, which is judged as medium risk; when the difference exceeds the 50% threshold, it indicates that the overturning moment is far beyond the safety boundary, and the assembly can no longer be stably supported by the fall arrestor points in the current position, which is judged as high risk, and the operator should immediately retract the connecting rod to the shortest state or adjust the grip posture to reduce the center of gravity offset distance. Different risk levels correspond to different warning signals: at low risk, the buzzer sounds a short, low-frequency beep once per second and the LED yellow light flashes slowly; at medium risk, the buzzer sounds a short, medium-frequency beep twice per second and the LED red light flashes slowly; at high risk, the buzzer sounds a continuous, high-frequency beep and the LED red light flashes rapidly.

[0074] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for a 3D printing modular electromagnetic adsorption multifunctional engineering operation device, characterized in that, Includes the following steps: Step 1: Calculate the current difference between adjacent detection cycles based on the real-time current of the magnetic head coil collected by the controller inside the handheld handle, and obtain the change in magnetic resistance of the magnetic head adhering to the surface of the target iron piece. Step 2: Based on the change in magnetic resistance, match the real-time deflection angle of the universal bending node of the connecting rod to obtain the initial spatial fit characteristics between the end face of the magnetic suction head and the contact surface of the target iron piece. Step 3: Based on the initial spatial fit characteristics, classify the edge magnetic leakage degree of the magnetic chuck under narrow slot operation conditions to obtain the spatial fit category between the end face of the magnetic chuck and the contact surface of the target iron piece. Step 4: Based on the holding time period corresponding to the spatial fit category, the demagnetizing pulse width of the pulse generator in the mounting base is accumulated segment by segment to obtain the total width value of the demagnetizing pulse after compensation. Step 5: Generate a pulse demagnetization control command based on the compensated total width of the demagnetizing pulse; Step 6: According to the pulse demagnetization control command, drive the magnetic suction head to execute the reverse magnetic field output to obtain the residual magnetism elimination state of the target iron surface; Step 7: Based on the residual magnetism elimination state and the real-time load of the overload sensor built into the hand handle, adjust the extension length of the electric connecting rod to obtain the space avoidance position of the magnetic head. Step 8: Based on the space avoidance position of the magnetic head, trigger the intelligent early warning module of the pre-reserved anti-fall hanging point on the mounting base to obtain the fall risk assessment result of the connecting rod.

2. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 1, characterized in that, Step 1 includes: Based on the first current value of the magnetic head excitation coil at the end of the current cycle and the second current value at the end of the previous cycle, which are collected at fixed intervals by the controller inside the handheld handle, the difference between the first current value and the second current value is calculated to obtain the excitation current difference between adjacent cycles. Based on the difference in excitation current between adjacent cycles, combined with the number of axial winding turns and the radial cross-sectional area of ​​the magnetic chuck excitation coil, the rate of change of magnetic induction intensity in the excitation magnetic circuit between the end face of the magnetic chuck and the surface of the target iron piece with time is determined, and the characteristics of magnetic induction change in the excitation magnetic circuit are obtained. Based on the characteristics of magnetic induction change in the excitation magnetic circuit, and combined with the angle between the contact force of the magnetic chuck end face acting on the target iron part along the axial component of the connecting rod and the normal of the magnetic chuck end face, the direction and magnitude of the magnetic reluctance change caused by the change in the air gap width between the magnetic chuck end face and the surface of the target iron part are determined, and the amount of magnetic reluctance change when the magnetic chuck adheres to the surface of the target iron part is obtained.

3. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 2, characterized in that, Step 2 includes: Based on the direction and amplitude of the change in magnetic resistance in the magnetic resistivity of the magnetic chuck against the surface of the target iron part, the non-uniform distribution of the air gap width between each edge position of the magnetic chuck end face and the surface of the target iron part is determined, and the uniformity characteristics of the magnetic chuck end face are obtained. Based on the direction of the line connecting the narrowest and widest points of the air gap in the uniformity of the magnetic head end face fit, the deflection angle value at the current moment is read from the angle sensor built into the universal bending node of the connecting rod, and the real-time orientation of the magnetic head end face in space is determined, thus obtaining the spatial orientation characteristics of the magnetic head end face. Based on the uniformity of the fit and the spatial orientation characteristics, the air gap width distribution at each edge position of the magnetic chuck end face is mapped to the corresponding contact area on the surface of the target iron part, thus obtaining the initial spatial fit characteristics between the magnetic chuck end face and the contact surface of the target iron part.

4. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 3, characterized in that, Step 3 includes: Based on the air gap width at each edge position in the initial spatial contact characteristics between the end face of the magnetic suction head and the contact surface of the target iron part, the edge segments with air gap width exceeding the normal closure threshold of the excitation magnetic circuit are extracted to obtain the set of edge leakage magnetic segments in the narrow gap condition. Based on the length of each edge segment and the average width of its air gap in the set of edge leakage magnetic sections in the narrow slot condition, the proportion of magnetic flux leaking outward through the edge air gap in the magnetic chuck excitation magnetic circuit to the total excitation magnetic flux is calculated, and the edge leakage magnetic degree value of the narrow slot condition is obtained. Based on the preset magnetic leakage degree range where the edge magnetic leakage degree value of the narrow gap working condition is located, the spatial contact state between the end face of the magnetic suction head and the contact surface of the target iron part is divided into one of full contact contact, partial edge floating contact, or large gap suspended contact, thus obtaining the spatial contact category between the end face of the magnetic suction head and the contact surface of the target iron part.

5. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 4, characterized in that, Step 4 includes: Based on the spatial contact type between the magnetic head end face and the target iron part contact surface, the corresponding demagnetization holding time duration and initial segmented pulse width are retrieved from the pre-stored contact type and demagnetization strategy mapping table in the controller in the hand handle, and the demagnetization strategy parameter group is obtained. Based on the demagnetization holding period duration and initial segmented pulse width in the demagnetization strategy parameter group, the demagnetization holding period is divided into multiple equal-length sub-periods. An initial segmented pulse width is allocated in each sub-period, and the segmented pulse widths of each sub-period are accumulated segment by segment in the order of the sub-periods to obtain the initial total width of the demagnetization pulse. Based on the initial total width of the demagnetizing pulse, and combined with the average air gap width of each edge segment in the set of leakage magnetic field segments at the edge of the narrow gap condition, a width compensation amount that is positively correlated with the average air gap width is applied to the initial total width of the demagnetizing pulse to obtain the compensated total width value of the demagnetizing pulse.

6. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 5, characterized in that, Step 5 includes: Based on the total width of the compensated demagnetizing pulse, according to the maximum duration of a single pulse output by the pulse generator in the mounting base, the total width of the compensated demagnetizing pulse is divided into multiple pulse output cycles, and the forward conduction period width and reverse turn-off period width within each pulse output cycle are determined to obtain the demagnetizing pulse timing parameter set. Based on the demagnetizing pulse timing parameter group, combined with the polarity configuration of the driving current between the output of the pulse generator and the excitation coil of the magnetic chuck and the upper limit of the driving current amplitude, a pulse demagnetizing control command containing the number of pulse cycles, the forward conduction width of each cycle, the turn-off width, and the current polarity reversal mark is encoded and generated.

7. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 6, characterized in that, Step 6 includes: According to the current polarity reversal mark in the pulse demagnetization control command, the pulse generator in the mounting base is controlled to output a demagnetization drive current to the magnetic head excitation coil in the opposite direction to the current in the excitation stage. This generates a reverse magnetic field at the end face of the magnetic head that cancels out the direction of the residual magnetic field of the target iron piece, thus obtaining the reverse demagnetization magnetic field output state. Based on the output state of the reverse demagnetizing magnetic field, after the last pulse output cycle specified by the pulse demagnetizing control command ends, the controller inside the hand handle collects the residual induced voltage value of the magnetic head excitation coil after demagnetization, and obtains the residual induced voltage of the coil after demagnetization. Based on the residual induced voltage of the coil after demagnetization, it is compared with the residual magnetism elimination judgment voltage threshold stored in the controller. If the residual induced voltage of the coil after demagnetization is lower than the residual magnetism elimination judgment voltage threshold, it is determined that the residual magnetism has been eliminated, and the residual magnetism elimination state of the target iron surface is obtained.

8. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 7, characterized in that, Step 7 includes: Based on the determination that the residual magnetism on the surface of the target iron part has been eliminated, the controller in the hand handle sends an excitation shutdown lock signal to the pulse generator in the mounting base, cutting off the power supply circuit of the magnetic suction head excitation coil, and obtaining the magnetic attraction force release confirmation state. Based on the confirmation of magnetic attraction release, the real-time tensile load value along the connecting rod axis detected by the overload sensor built into the hand handle at the current moment is read to determine whether the electric connecting rod is in an overload state of bearing heavy objects, and the bearing state of the connecting rod is obtained. Based on the determination that the connecting rod is not overloaded, the controller inside the hand handle sends a retraction command to the telescopic drive motor built into the electric connecting rod, driving the electric connecting rod to shorten its extension length along the axial direction, so that the end face of the magnetic suction head leaves the close working area of ​​the target iron surface, thus obtaining the spatial avoidance position of the magnetic suction head.

9. The control method for the 3D printing modular electromagnetic adsorption multifunctional engineering operation device according to claim 8, characterized in that, Step 8 includes: Based on the current extension length of the electric connecting rod in the space avoidance position of the magnetic chuck and the real-time position of the magnetic chuck mounting base in space, the offset distance of the center of gravity of the connecting rod and mounting base assembly relative to the reserved anti-fall hanging point of the mounting base in the vertical direction is calculated, and the center of gravity offset characteristics of the assembly are obtained. Based on the combined weight center offset characteristics, and combined with the real-time tensile load value of the overload sensor built into the hand handle after the electric connecting rod retracts, the overturning moment borne by the fall arrest point is calculated, and the overturning moment value of the fall arrest point is obtained. Based on the overturning moment value of the fall arresting point, it is compared with the fall risk overturning moment threshold pre-stored in the intelligent early warning module. If the overturning moment value of the fall arresting point is greater than the fall risk overturning moment threshold, a high-risk fall warning signal is generated and the fall risk probability level is calculated to obtain the fall risk assessment result of the connecting rod.

10. A 3D printing modular electromagnetic adsorption multifunctional engineering operation device for performing the method as described in any one of claims 1 to 9, characterized in that, include: The magnetic suction head has an excitation coil inside, which is wound axially on a coil frame. The end face of the magnetic suction head is used to adhere to and adsorb the surface of the target iron part. The mounting base is located on the non-adsorption end of the magnetic head. The mounting base integrates a pulse generator, and the output end of the pulse generator is electrically connected to the excitation coil inside the magnetic head. The side wall of the mounting base is reserved with anti-fall hanging points. The electric connecting rod has its front end connected to the mounting base. The electric connecting rod has a built-in telescopic drive motor and a universal bending node. An angle sensor is installed at the universal bending node. The handle connects to the rear end of the electric connecting rod. The handle contains a battery, a controller, and an overload sensor. The controller is electrically connected to the current acquisition terminal of the excitation coil, the control terminal of the pulse generator, the drive terminal of the telescopic drive motor, the signal output terminal of the angle sensor, and the signal output terminal of the overload sensor. An intelligent early warning module is integrated at the fall arrest point, and the intelligent early warning module communicates with the controller.

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