A non-contact measurement method for wear of grab blade edge based on laser triangulation

Abstract

The present application relates to the technical field of non-contact measurement, in particular to a kind of non-contact measurement method of grab blade edge wear based on laser triangulation, the present application is by obtaining bucket profile and blade profile, according to the relative pose change of blade under different opening degree Actual hinge shaft is determined, and bucket body coordinate system is established;According to the relative pose of closing and opening stroke, determine the equivalent mechanism clearance and different step, form the mechanism deviation set;After the pose of two petals is corrected, the first contact is determined by point closing, the zero gap constraint is established, and the wedge extension blade edge offset is calibrated;The inner and outer wedge surfaces of the homing section are fitted and extended to intersect, and the minimum wear section is determined by excluding abnormal points to construct a virtual original profile;The functional blade edge is obtained by extrapolating the blade edge offset, and the blade edge wear distribution is obtained according to the retreat amount and section loss amount of the functional blade edge relative to the virtual original profile.

Description

Technical Field

[0001] This invention relates to the field of non-contact measurement technology, specifically to a non-contact measurement method for the wear of a grab bucket blade based on laser triangulation. Background Technology

[0002] Grab buckets are the main material handling mechanisms in port bulk cargo loading and unloading, waste incineration power generation, and dredging operations. The cutting edge of the bucket's front edge bears abrasive wear and impact loads during insertion into the material pile and during the closing process, making it a typical wear part. After the cutting edge wears down, a gap appears between the two cutting edges along the contact line in the closed configuration, leading to material spillage and a decrease in the amount of material grabbed. Therefore, it is necessary to measure the cutting edge wear regularly.

[0003] Currently, the measurement of cutting edge wear mainly relies on manual contact measurement after the machine stops and the bucket is lowered. Calipers and templates are used to measure the remaining height and thickness of the cutting edge, resulting in low efficiency, large result dispersion, and requiring operators to be close to large suspended components. To address this, a non-contact measurement method based on laser triangulation has been introduced in this field: a laser projects a laser plane onto the surface being measured, an imaging device receives the diffuse reflected light from the surface, and the coordinates of the contour points of the measured section are calculated based on trigonometric relationships. The measured contour is then compared with a reference contour to determine the wear amount. This method has already been applied in applications such as rail cross-section wear and tool wear.

[0004] However, the above comparison method is based on the premise that the measured working surface is a rigid single component and that all its observed shape deviations originate from its own morphological changes. The grab's jaws are the end components of a spatial closed-chain mechanism, and the two jaws' cutting edges need to align with each other. The shape deviations it exhibits during scanning include not only the wear of the cutting edge material but also the play between the hinge pin and the lug, as well as the jaw sway caused by the unequal lengths of the tie rods or ropes on both sides. These three factors are of roughly equal magnitude and superimposed along the cutting edge direction. Therefore, when performing a contour scan under a single shape and comparing it with a reference contour, the mechanical shape deviations will be included in the wear amount, and the measured results cannot reflect the true amount of cutting edge material loss.

[0005] To address this, a non-contact measurement method for the wear of the grab bucket's cutting edge based on laser triangulation is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a non-contact measurement method for the wear of the grab bucket cutting edge based on laser triangulation. By constructing a virtual original profile through actual hinge axis calibration, structural deviation correction, zero-gap contact calibration, and wedge surface extension, the wear of the cutting edge distributed along the cutting edge is obtained.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A non-contact measurement method for grab bucket cutting edge wear based on laser triangulation includes: Obtain the outline of the bucket body and the outline of the blade in a section perpendicular to the hinge axis, and calculate the relative pose of the blade; define the opening with the relative pose, determine the actual hinge axis by the relative pose change of the measuring points distributed along the blade line in the opening of the closed interval, and establish the bucket body coordinate system. Based on the relative pose of the closed stroke and the open stroke, the equivalent mechanism clearance referred to the cutting edge is obtained; the component with the same sign in the forward and reverse strokes in the difference between the relative rotation angles of the two lobes is taken as the asynchronous mechanism quantity; the equivalent mechanism clearance is combined to form the mechanism deviation set. The two lobes are reduced to the same reference configuration by the set of institutional deviations. The jog closure is performed and the rate of change of the relative pose of the two lobes with the driving action is monitored. The first engagement contact is determined by the inflection point of the rate of change. The relative pose at the moment of contact is used as the zero gap constraint to calibrate the wedge surface extension edge offset of the measuring point. Fit the inner and outer wedge surfaces of the repositioned section and extend to find the intersection. After eliminating points that exceed the envelope of the intersection point, refit the section. Take the section with the largest forward extension position of the intersection point as the minimum wear section and extend to construct a virtual original contour. Extrapolate the offset to each measuring point according to the wedge surface geometry to obtain the functional edge. Obtain the edge wear based on the functional edge and the virtual original contour.

[0008] Preferably, the calculation of the relative pose of the blade includes: in the same section perpendicular to the hinge axis, using laser triangulation to obtain the contour and simultaneously cutting the outer surface of the bucket body side plate, the outer surface of the hinge seat, the exposed section of the mounting and fitting surface on the back of the blade, the inner wedge surface of the blade, and the outer wedge surface of the blade; determining the reference orientation of the bucket body by the direction of the two contours of the outer surface of the bucket body side plate and the outer surface of the hinge seat and the included angle between the two contours; The blade orientation is determined by the exposed section of the mounting surface on the back of the blade. When the bucket flap rotates to the inside of the closed zone and the mounting surface on the back of the blade is blocked by the opposite bucket flap, the blade orientation is determined by the unworn section of the outer wedge surface of the blade near the mounting edge. The two blade orientations are connected at the overlapping opening before the blocking occurs. The position component and the rotation component of the blade orientation relative to the bucket body reference orientation are taken as the relative pose of the blade. Multiple frames of contour are collected at the same opening and the relative pose of the blade is averaged over time to suppress the fluctuation of the interception position caused by the change of the incident angle on the wedge surface due to the swing of the grab bucket suspension.

[0009] Preferably, establishing the bifurcation body coordinate system includes: defining the opening degree using the rotation component in the relative pose; causing the bifurcation to stop sequentially at adjacent opening degrees within the closed interval, distributing measuring points along the cutting edge according to the position of the segmented cutting edge, with each measuring point providing the change in the relative pose of the cutting edge between adjacent opening degrees, and summing the changes in the measuring points according to their positions along the cutting edge to form the displacement field of the same rigid body, with the spacing between the measuring points distributed along the cutting edge forming the baseline of the displacement field, and the length of the baseline bearing the solution constraint caused by the small displacement under small opening degree difference conditions; determining the actual hinge axis based on the displacement in the displacement field, establishing the bifurcation body coordinate system with the actual hinge axis as the axis reference and the orientation of the mounting and fitting surface on the back side of the cutting edge as the direction reference; and uniformly transforming the inner wedge surface profile and outer wedge surface profile of the cutting edge under each opening degree to the bifurcation body coordinate system to obtain the repositioning section.

[0010] Preferably, the set of structural deviations includes: within the closed interval, the bucket flaps sequentially complete the closing stroke and the opening stroke, with the tie rod bearing the closing driving tension during the closing stroke and the tie rod bearing the reverse action of the bucket flaps' own weight during the opening stroke, and the pin abutting against the opposite sides of the shaft hole during the two strokes respectively; when the two strokes pass through the same opening degree, the relative poses of the blade plates are taken respectively, and the difference between the relative poses of the two blade plates is taken as the equivalent structural clearance converted to the blade line, and the direction of action of the equivalent structural clearance is determined by the projection of the tie rod axis in the cross section; the value is repeatedly taken at several opening degrees within the closed interval, and the projection direction of the tie rod axis is different at each opening degree, to obtain the distribution of the equivalent structural clearance with the direction of action, and the distribution of the equivalent structural clearance with the direction of action corresponds to the non-circular wear of the shaft hole; The difference in relative rotation angles between the corresponding measuring points on the left and right lobes is taken. The component of the difference in relative rotation angles with the same sign in the closing stroke and opening stroke, and which changes monotonically with the opening, is taken as the asynchronous quantity. The asynchronous quantity represents the stable asynchronous state of the two lobes' strokes. The component of the difference in relative rotation angles with opposite signs in the closing stroke and opening stroke is marked as the friction and guide resistance component. The equivalent mechanism play, the distribution of the equivalent mechanism play with the direction of action, and the asynchronous quantity constitute the mechanism deviation set.

[0011] Preferably, the wedge-surface extension edge offset of the calibration measurement point includes: correcting the relative pose of the left and right lobes of the cutting edge with the equivalent mechanical clearance and asynchronous amount of the concentrated mechanical deviation, reducing the left and right lobes to the same reference configuration, and obtaining the relative pose of the two lobes; closing the two lobes towards each other by jogging, recording the motion amount of the closing drive and the relative pose of the two lobes step by step, and taking the rate of change of the relative pose of the two lobes with the motion amount. The point where the rate of change decreases is taken as the inflection point, and the measuring point at the inflection point is taken as the contact measuring point. The two lobes are retracted and the jogging closure is repeated once. When the two inflection point poses are consistent, they are marked as candidate mating contact. When they are inconsistent, they are marked as uncertain stop. After cleaning the cutting edge area, the jogging is repeated. The relative poses of the two lobes at the moment of contact determine that the edge clearance at the contact measuring point is zero. The difference between the edge position under the zero clearance condition and the intersection point obtained by the extension of the inner wedge surface and the outer wedge surface of the cutting plate at the same moment is taken as the wedge surface extension edge offset. The wedge surface extension edge offset corresponds to the passivation geometry of the edge.

[0012] Preferably, the virtual original contour is constructed by extension, including: selecting fitting sections of the inner wedge surface and the outer wedge surface of the blade for the return section respectively; fitting the inner wedge surface and the outer wedge surface of the blade for the fitting section, extending and intersecting in the direction of the blade edge to obtain the wedge surface extension intersection point of each return section; using the position of each wedge surface extension intersection point in the coordinate system of the blade body to form the intersection point envelope, and only within the same service cycle after the most recent blade replacement or welding and surface cleaning, the contour points that exceed the intersection point envelope and are isolated and protruding are treated as attached material or spatter and removed. Compare the forward extension positions of the wedge surface extension intersection points of the repositioned section along the normal of the wedge surface after re-intersection, and take the section with the largest forward extension position as the minimum wear section; extend along the cutting edge with the wedge angle and wedge surface orientation of the minimum wear section, and keep the wedge angle constant and the wedge surface orientation continuously change with the cutting edge direction during the extension process to obtain the virtual original contour of the cutting edge in the current repair state.

[0013] Preferably, obtaining the cutting edge wear amount includes: taking the change between the wedge angle and the intersection of the wedge surface extension of the measuring point relative to the wedge angle and the intersection of the wedge surface extension of the contact measuring point, and pushing the wedge surface extension cutting edge offset outward to the measuring point according to the change to obtain the functional cutting edge of the measuring point; taking the amount of retreat of the functional cutting edge of the measuring point relative to the virtual original contour along the wedge surface normal and the amount of cross-section loss as the cutting edge wear amount, and arranging them along the cutting edge line point by point to obtain the cutting edge wear amount distribution; Verify the measurement point at the minimum wear section and the contact measurement point: if the two measurement points coincide, it is confirmed that the blade wear distribution is valid; if the two measurement points do not coincide, it is determined that there is residual material at the contact measurement point or local chipping at the minimum wear section. Remove the material from the corresponding blade section and re-collect the data. Substituting the edge wear distribution and the set of mechanical deviations into the closed configuration, we obtain the mating line gap distribution, and decompose the mating line gap into the contribution of blade material loss, the contribution of equivalent mechanical clearance, and the contribution of asynchronous clearance.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention utilizes laser triangulation to simultaneously acquire the bucket body contour and the blade contour. Based on the relative pose changes of measuring points distributed along the blade line at different opening degrees within the closed interval, the actual hinge axis is calculated inversely. A bucket body coordinate system is then established, unifying the inner and outer wedge surface contours of the blade obtained from different opening degrees and measuring points to the same coordinate reference. This method does not rely on the design hinge axis position or nominal assembly dimensions of the grab bucket, reducing the impact of long-term wear of pins and shaft holes and installation deviations on the contour reference. It ensures that wear measurement is based on the current actual motion geometry of the grab bucket, improving the spatial consistency between contour data at different opening degrees and blade line positions, and providing a stable geometric reference for non-contact measurement of blade wear.

[0015] 2. This invention determines the equivalent mechanism play by utilizing the relative positional difference of the cutting edge under the same opening stroke and closing stroke. It also identifies non-circular wear of the shaft hole by combining the play distribution with the direction of action. Simultaneously, it extracts asynchronous quantities from the relative rotation angle difference between the two halves, distinguishing mechanism wear, transmission asynchrony, and cutting edge material wear. By reducing the left and right halves to the same reference configuration through a set of mechanism deviations before performing cutting edge contact determination, it avoids miscalculating positional deviations caused by pin clearance, tie rod length differences, and changes in movement direction into the cutting edge wear. This ensures that the measurement results correspond to the geometric loss of the cutting edge itself and simultaneously obtains mechanism state information, improving the accuracy of wear source differentiation.

[0016] 3. This invention identifies the initial engagement contact by measuring the inflection point of the rate of change of the relative pose of the two lobes with the amount of driving motion during the jogging closure process. It then eliminates false contacts caused by material clamping by using repeated closure results. Based on this, a zero-gap constraint is established, and the wedge surface extension edge offset is calibrated. Subsequently, the inner and outer wedge surfaces are fitted, extended, and abnormal contour points are removed. A virtual original contour is constructed using the minimum wear section, and the edge offset is then geometrically extrapolated along the wedge surface to obtain the functional edge at each measuring point. The wear amount is obtained by comparing the functional edge with the virtual original contour. This eliminates the need for pre-storing the new blade profile and is adaptable to on-site measurements under conditions of edge dulling, localized chipping, and residual deposits. Attached Figure Description

[0017] Figure 1 A schematic diagram of a non-contact measurement method for the wear of a grab bucket cutting edge based on laser triangulation provided by the present invention; Figure 2 A schematic diagram of the mechanism deviation separation process provided by the present invention; Figure 3 This is a schematic diagram of the actual contact determination and bias calibration process provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0019] Example 1: The object tested in this embodiment is a four-cable double-lobed grab bucket used for loading and unloading coal at a port bulk cargo terminal. The grab bucket consists of two arc-shaped lobes on the left and right, tie rods on both sides, an upper crossbeam, a lower crossbeam, and pins, forming a closed-chain mechanism. The lobes rotate relative to each other around hinges located at both ends of the lower crossbeam, with an opening and closing angle stroke of 90 to 110 degrees. The leading edge of each lob is composed of several replaceable wear-resistant steel segmented cutting plates along the cutting edge direction. The cross-section of each segmented cutting plate is wedge-shaped, with an inner wedge surface facing inward and an outer wedge surface facing outward. The intersection of the two wedge surfaces at the front end forms the cutting edge. The segmented cutting plates are fixed to the mounting base on the leading edge of the lobes by fasteners. The mounting and contacting surface on the back side is in contact with the mounting base, and there is an exposed section of the mounting and contacting surface on the inner side of the lobes along the cutting edge direction that is not covered by the mounting base. During service, the segmented cutting plates are subjected to abrasive wear from coal and impact from lumps, and are repaired by welding after wear.

[0020] A fixed gantry-shaped support is set up at the necessary handover station for grab hoisting. Measuring points are set along the crossbeam of the gantry-shaped support according to the position of the segmented cutting edge. Each segmented cutting edge corresponds to one measuring point, and the measuring point is located in the middle of the segmented cutting edge along the cutting line direction.

[0021] Each measuring point is equipped with a pair of line structured light profile sensors. The laser planes of the two sensors coincide in space, and this coinciding plane is vertically set and perpendicular to the hinge axis direction when the grab bucket is docked. One sensor enters from above inside the grab lobe, covering the inner wedge surface of the blade, the edge area, and the exposed section of the mounting surface; the other sensor enters from above outside the grab lobe, covering the outer wedge surface of the blade, the edge area, the outer surface of the grab body side plate, and the outer surface of the hinge seat. The coordinate relationship between the two sensors in the same laser plane is calibrated once after the station is built and then used as a fixed quantity. The laser planes of each measuring point are simultaneously calibrated to the same station coordinate system, and the blade line position corresponding to the measuring point number is saved. A blue-violet band semiconductor line laser is selected, and a narrow-band filter with the same wavelength as the laser is placed in front of the imaging device to suppress sunlight and material yard lighting, and to reduce the difference in diffuse reflection intensity between the welded rough surface and the rusted surface.

[0022] Communication is established between the control cabinet and the measurement program for the grab bucket closing drive. The communication content is limited to action start and stop commands and position status signals. The displacement of the closed drum is only used as the basis for counting the jog step distance and does not participate in the calculation of any position or orientation quantity.

[0023] Please see Figure 1This invention provides a non-contact measurement method for the wear of a grab bucket's cutting edge based on laser triangulation. The technical solution is as follows: The bucket body profile and the blade profile are obtained within a section perpendicular to the hinge axis, and the relative pose of the blade is calculated. The opening is defined by the relative pose, and the actual hinge axis is determined by the relative pose changes of measurement points distributed along the blade line within the opening of the closed interval, establishing a bucket lobe coordinate system. The relative pose is taken based on the opening of the closed stroke and the opening stroke to obtain the equivalent mechanism clearance referred to the blade line. The component with the same sign in both forward and reverse strokes in the difference between the relative rotation angles of the two lobes is taken as the asynchronous quantity. The equivalent mechanism clearance is combined to form a set of mechanism deviations. The two lobes are reduced to the same reference configuration using the set of structural deviations. The relative pose of the two lobes is jogged and closed, and the rate of change of the relative pose of the two lobes with the driving action is monitored. The inflection point of the rate of change is used to determine the first engagement contact. The relative pose at the moment of contact is used as the zero-gap constraint. The wedge surface of the measuring point is extended to determine the edge offset. The inner and outer wedge surfaces are fitted to the repositioned section and extended to find the intersection. Points that exceed the envelope of the intersection point are removed and refitted. The section with the largest forward extension position of the intersection point is taken as the minimum wear section. The virtual original contour is constructed by extension. The functional edge is obtained by extrapolating the offset to each measuring point according to the wedge surface geometry. The edge wear is obtained based on the functional edge and the virtual original contour.

[0024] The grab bucket is suspended above the workstation without touching the ground or carrying any material. Two sensors at each measuring point synchronously acquire data at a fixed frame rate. For each frame, the center line of the light stripe is extracted based on the grayscale distribution after narrowband filtering: the grayscale centroid is taken along the column direction of the image to obtain the sub-pixel center position of the light stripe; columns with saturated grayscale or grayscale below the noise threshold are marked as invalid columns and do not participate in subsequent fitting. The center position of the light stripe is converted into the coordinates of a two-dimensional contour point in the laser plane according to the calibrated laser triangulation relationship to obtain a cross-sectional contour.

[0025] The acquired cross-sectional profiles are stored using a three-level index. The first-level index is the serial number of the measuring point along the cutting edge; the second-level index is the opening degree at which the measurement was performed; and the third-level index is the stroke to which the measurement was performed, with the value being either a closed stroke or an open stroke. Therefore, two cross-sectional profiles with the same measuring point, the same opening degree, but different strokes can be directly aligned and their differences calculated.

[0026] Further, the relative pose of the blades is calculated, including: within the same section perpendicular to the hinge axis, simultaneously capturing the outer surface of the bucket side plate, the outer surface of the hinge seat, the exposed section of the blade back mounting surface, the inner wedge surface of the blade, and the outer wedge surface of the blade using a contour obtained by laser triangulation; determining the bucket reference orientation based on the direction of the two contour segments of the bucket side plate outer surface and the hinge seat outer surface, and the included angle between the two contour segments; when the bucket side plate outer surface fails under material accumulation conditions, determining the bucket reference orientation solely based on the hinge seat outer surface; determining the blade orientation based on the exposed section of the blade back mounting surface, where the blade back mounting surface is located outside the material shearing path and does not experience material loss during service; the bucket flap rotates to... When the mounting surface of the inner side of the closed section and the back side of the blade is blocked by the opposite bucket petal, the blade orientation is determined by the unworn section of the outer wedge surface of the blade near the mounting edge. The two blade orientations are connected at the overlapping opening before the blocking occurs. The position component and the rotation component of the blade orientation relative to the bucket body reference orientation are taken as the relative pose of the blade. The grab bucket suspension swing, rotation, lifting and lowering, and the thermal deformation of the measuring support act simultaneously on the bucket body contour and the blade contour, which are eliminated in the process of taking the blade orientation relative to the bucket reference orientation. Multiple frames of contour are collected at the same opening and the time average is taken for the relative pose of the blade to suppress the fluctuation of the interception position caused by the change of the incident angle on the wedge surface due to the grab bucket suspension swing.

[0027] Specifically, for each cross-sectional profile, segments are formed based on the continuity and direction of the profile points: scanning along the profile from one side of the bucket towards the blade edge, points where the distance between adjacent points exceeds the point spacing limit are considered profile breaks, and points where the turning angle of the profile exceeds the turning angle limit are considered surface boundaries. This divides a cross-sectional profile into several straight segments. Then, based on the position and direction of each straight segment in the sensor's field of view, and combined with the known structural arrangement of the grab bucket, each straight segment is designated as: the outer surface segment of the bucket body side plate, the outer surface segment of the hinge seat, the exposed segment of the blade back mounting surface, the inner wedge surface segment of the blade, and the outer wedge surface segment of the blade. The outer surface segment of the bucket body side plate and the outer surface segment of the hinge seat are collectively called the bucket body profile, the exposed segment of the mounting surface is called the blade reference profile, and the inner and outer wedge surface segments are collectively called the blade working profile. The turning angle limit and point spacing limit are determined by the actual angle between the sensor's lateral resolution and the measured surface, taking the turning angle corresponding to half the angle between adjacent surfaces and the point spacing corresponding to a multiple of the lateral resolution.

[0028] Least-squares linear fitting was performed on the outer surface of the side plate and the outer surface of the hinge, respectively. Before fitting, isolated points deviating from the main body were eliminated by random sampling. The direction of the two fitted lines and the angle between them were taken to determine the reference orientation of the bucket, that is, a position component and a rotation component of the bucket in the laser plane.

[0029] During loading and unloading operations, the side plates of the bucket body are covered by falling material, which reduces the effective point count of that section's profile. When the effective point count of the outer surface section of the bucket body side plate is lower than the limit for the effective point count of the profile, that section is no longer used. Instead, the reference orientation of the bucket body is determined solely by the outer surface section of the hinge seat: the outer surface of the hinge seat is the outer cylindrical surface of a rotating body, and its cross-section in the laser plane is an arc. A least-squares fit with radius constraints is performed on this arc, and the direction of the line connecting the center position and the two ends of the arc is taken to determine the reference orientation of the bucket body. The hinge seat is located at the rotation center of the bucket petals, facing upwards, and does not receive falling material, so it can still be used under material accumulation conditions. The process of obtaining the limit for the effective point count of the profile is as follows: under the condition that the grab bucket is clean and free of material accumulation, the cross-sectional profile of this section of the surface is collected and its effective point count is counted; then, the number of points participating in the fitting is gradually reduced and the fitting is repeated, and the minimum number of points corresponding to the angular uncertainty of the fitted orientation does not exceed the measurement uncertainty allocation value is taken.

[0030] The blade reference profile is fitted with a least-squares straight line, and the direction of the fitted line and its distance from the sensor reference point are taken to determine the blade orientation. The mounting surface on the back side of the blade is located on the back side of the segmented blade, facing the mounting seat, and is outside the path of coal flowing along the inner surface of the bucket. It does not come into contact with the material during service, so there is no material loss, and its geometry remains unchanged throughout the entire service life.

[0031] When the bucket flap rotates into the inner side of the closed zone, the exposed section of the mounting surface will be blocked by the opposite bucket flap, and the number of effective points will drop below the limit. At this time, the blade orientation is determined by a section on the outer wedge surface of the blade located between the mounting edge and the starting position of the material shearing path. This section does not slip relative to the material during the gripping process. The connection between the two references is completed on several overlapping openings before the blocking occurs: at each overlapping opening, the angular component in the blade orientation is calculated once for the exposed section of the mounting surface and the aforementioned section of the outer wedge surface, and the difference between the two is taken; if the maximum value of this difference on several overlapping openings does not exceed the angular consistency limit, it is considered that the section of the outer wedge surface has not been worn, and it is continued; if it exceeds the limit, it is determined that the section has been worn and does not qualify as a reference, the measurement is terminated and a prompt is output.

[0032] The positional and angular components of the blade's orientation relative to the bucket's reference orientation are taken as the blade's relative pose. The suspension swing, rotation around the lifting point, and lifting and lowering of the grab bucket, as well as the thermal deformation of the gantry frame and the zero-point drift of the sensors, all act simultaneously on the bucket body profile and blade profile within the same cross-sectional profile at the same time, and are eliminated during the relative measurement process. Since the bucket body and segmented blades are both steel components, located in the same ambient temperature field, and all data acquisition in this method is completed within a single grab bucket hover, the difference in their thermal expansion is far lower than the measurement uncertainty and does not constitute a non-common-mode component requiring separate compensation.

[0033] Several frames were continuously acquired at the same opening, and the relative pose of the blade plate calculated frame by frame was averaged over time. The grab bucket's suspension and swinging motion is a low-frequency reciprocating motion, which changes the incident angle of the laser plane on the wedge surface, causing the interception position of the light stripe on the wedge surface to fluctuate back and forth; time averaging makes the mean of this fluctuation tend to zero. The number of frames acquired was increased until the difference between two adjacent average results did not exceed the pose repeatability limit. The rotation consistency limit and the pose repeatability limit were determined by repeatedly acquiring data at the same opening several times, and the dispersion of the difference between the rotation components given by the two references and the dispersion of the relative pose of the blade plate were calculated respectively, and the upper statistical quantile of each dispersion was taken.

[0034] Furthermore, a coordinate system for the body of the clasp is established, including: defining the opening degree by the angular component in the relative pose of the blades; the motion quantity of the closing drive is only used to generate changes in the opening degree and does not participate in the opening degree definition; the elastic elongation of the closing wire rope, the change in the pulley block ratio, and the change in the winding radius of the drum do not enter the opening degree; within the closed interval, the clasp is made to stop at several adjacent opening degrees in sequence, and measuring points are distributed along the blade line according to the position of the segmented blades. Each measuring point gives the change in the relative pose of the blades between adjacent opening degrees. The changes of each measuring point are summarized into the displacement field of the same rigid body according to the position of the measuring point along the blade line. The spacing between the measuring points distributed along the blade line constitutes the baseline of the displacement field. The length of the baseline bears the solution constraint caused by the small displacement under the condition of small opening degree difference; the actual hinge axis is determined based on the displacement in the displacement field, and the clasp coordinate system is established with the actual hinge axis as the axis reference and the orientation of the mounting and fitting surface on the back side of the blade as the direction reference. The position of the actual hinge axis relative to the center of the fitted arc of the hinge seat is recorded as the hinge seat state quantity; when the opening is constant, it is recorded as the geometric offset; when the opening changes, the hinge seat is determined to be unstable and the measurement is terminated; the inner wedge surface profile and outer wedge surface profile of the blade plate under each opening are uniformly transformed to the body coordinate system of the ferrule to obtain the return section.

[0035] Specifically, the angular component in the relative pose of the blades is used as the opening. The closed wire rope exhibits elastic elongation and structural elongation; the pulley system ratio varies with the bucket lobe configuration; and the effective winding radius of the drum varies with the number of winding layers. Therefore, there is no stable one-to-one correspondence between the closing drive's motion and the bucket lobe configuration. The opening is defined by the relative pose of the blades themselves, and the above three factors are not included in the opening calculation. In this step, the closing drive's motion is only used to instruct the bucket lobe to rotate and is not considered an independent variable.

[0036] Within the closed interval, several adjacent openings are selected. The difference between adjacent openings is taken as the maximum angular increment that keeps the measured cross-section intact within the sensor's field of view. This increment is determined by the ratio of the cross-sectional height of the segmented blade to the sensor's field of view height. After taking the increment, the blade edge and the exposed section of the mounting surface are simultaneously visible within the same field of view. The blades stop sequentially at each opening, and each stop completes one calculation of the relative pose of the blade.

[0037] Under adjacent openings, the intersection of the fitted straight line of the mounting surface and the mounting boundary is taken as the corresponding feature point. After transforming to the work position coordinate system, the difference is calculated to obtain the displacement vector of the measuring point. The displacement vectors of all measuring points are arranged according to the position of the measuring points along the blade direction to form a displacement field. The displacement field is the collection of displacements of all points of the same rigid body in the same small rotation.

[0038] When a rigid body rotates about a fixed axis, the displacement vector at each point is perpendicular to the radius vector from that point to the axis and also perpendicular to the axial direction. Therefore, for the displacement vector of each measuring point, a plane perpendicular to the displacement vector is drawn through the midpoint of that point, resulting in a perpendicular bisector. These perpendicular bisectors intersect in space, and the common intersection line of all perpendicular bisectors is taken as the actual hinge axis of the lobes. When the perpendicular bisectors are not strictly collinear due to measurement noise, the line with the smallest sum of the squares of the distances between the perpendicular bisectors is taken as the common intersection line. At least three corresponding feature points are required for the solution. If corresponding feature points are missing, the perpendicular bisectors are approximately parallel, or the fitting residual of the common intersection line exceeds the uncertainty of the actual hinge axis position, the measurement is terminated, and a new opening is selected.

[0039] Using the actual hinge axis as the axial reference, and the intersection of the axial axis and the laser plane of the reference measuring point as the origin, a coordinate system for the bucket body is established using the axial direction and the in-plane orientation of the mounting and mating surface. Within the coordinate system determined by the bucket body reference orientation, the position of the center of the circle obtained by fitting the actual hinge axis relative to the outer surface arc of the hinge seat is taken as the hinge seat state quantity. There is a fit clearance between the bucket petal pin and the hinge seat shaft hole, and the hinge seat body may also undergo plastic deformation under long-term impact, both of which cause the actual hinge axis to deviate from the center of the hinge seat. The hinge seat state quantity is calculated at each opening degree: if the difference between the hinge seat state quantities at each opening degree does not exceed the hinge seat state limit, it indicates that the deviation is a constant geometric offset, and the hinge seat state quantity is recorded without performing a secondary translation on the coordinate system established with the actual hinge axis; if the difference between the hinge seat state quantities at each opening degree exceeds the limit, it indicates that the hinge seat has changed position during rotation, and the hinge seat is determined to be unstable. The measurement is terminated and a prompt is output because the body coordinate system is unstable at this time, and all subsequent measurements lose their basis. The state limit of the hinge is determined by the position uncertainty of the actual hinge axis obtained by solving the common intersection of the perpendicular planes, and is taken as a multiple of this uncertainty.

[0040] The working profiles of the blade at each opening degree, namely the profile points of the inner and outer wedge sections, are transformed from the laser plane coordinate system to the body coordinate system of the blade. The result is called the repositioning section. The repositioning section is stored according to a three-level index of measuring points, opening degree, and stroke, corresponding one-to-one with the original profile.

[0041] Furthermore, referring to Figure 2This constitutes a set of structural deviations, including: within the closed interval, the bucket petals complete one closing stroke and one opening stroke in succession; during the closing stroke, the pull rod bears the closing driving tension; during the opening stroke, the pull rod bears the reverse action of the bucket petals' own weight; and the pin abuts against the opposite sides of the shaft hole in the two strokes respectively. When the two strokes pass through the same opening, the relative poses of the blade plates are taken respectively. The difference between the relative poses of the two blade plates is taken as the equivalent mechanism clearance converted to the cutting edge. The direction of action of the equivalent mechanism clearance is determined by the projection of the tie rod axis in the cross section. The value is repeatedly taken at several openings in the closed interval. The projection direction of the tie rod axis is different at each opening, so the distribution of the equivalent mechanism clearance with the direction of action is obtained. The distribution of the equivalent mechanism clearance with the direction of action corresponds to the non-circular wear of the shaft hole. The difference in relative rotation angle between the corresponding measuring points on the left and right lobes is taken. The component of the difference in relative rotation angle where the signs of the closed stroke and the opening stroke are the same and the change is monotonically with the opening is taken as the asynchronous quantity. The asynchronous quantity represents the stable asynchronous state of the stroke of the two lobes. The component of the difference in relative rotation angle where the signs of the closed stroke and the opening stroke are opposite is marked as the friction and guide resistance component. The friction and guide resistance component is not included in the asynchronous quantity. The set of mechanism deviations is composed of the equivalent mechanism free play, the distribution of the equivalent mechanism free play with respect to the direction of action, and the asynchronous quantities.

[0042] Specifically, within the closed section, one closing stroke and one opening stroke are executed sequentially. During the closing stroke, the closing drive applies tension, which is transmitted to the lower crossbeam via the pulley system. The tie rods on both sides are under tension, and the bucket petals rotate towards each other. During the opening stroke, the closing drive is relaxed until the bucket petals are driven only by their own weight. Under the action of their own weight, the bucket petals rotate in opposite directions, and the direction of the internal force in the tie rods is reversed accordingly.

[0043] The condition that the bucket's petals automatically rotate to the set opening and stabilize after the closing drive is released is used to confirm that the force direction has been reversed. For some bucket shapes, the closing rope retains some tension during the opening process; in this case, the direction of the internal force in the pull rod is not completely reversed, the pin does not change direction, and the subsequent equivalent mechanism play will be smaller. If the bucket petals do not automatically reach their position, it is determined that the closing drive has not been fully released, and the opening stroke is re-executed. After the force direction is reversed, the pin abuts against opposite sides of the shaft hole in both strokes.

[0044] When the two strokes pass through the same opening, the relative pose of the cutting edge is taken once for each stroke, and the difference between the two poses is taken as the equivalent mechanism play referred to the cutting edge. The direction of action of the equivalent mechanism play is determined by the projection direction of the tie rod axis in the laser plane.

[0045] The above values ​​are repeated at several opening degrees within the closed interval. As the opening degree changes, the attitude of the pull rod axis relative to the bucket petals changes, and its projection direction in the laser plane changes accordingly. Therefore, the equivalent mechanism play obtained at each opening degree corresponds to different force directions on the shaft hole. The values ​​at each opening degree are arranged according to the action direction to obtain the set of equivalent mechanism play values ​​with respect to the action direction. When the difference between the values ​​in each direction in the set exceeds the non-circular wear limit, it is determined that non-circular wear has occurred in the shaft hole, and the maximum value in each direction is taken as the representative value of the current equivalent mechanism play of the grab bucket. The non-circular wear limit is determined by repeatedly performing the closed stroke and the opening stroke several times at the same opening degree, statistically analyzing the dispersion of the equivalent mechanism play, and taking the upper statistical quantile.

[0046] This method only provides the equivalent quantity converted to the cutting edge, without decomposing the play to each pin. The flap, the two side tie rods, the upper crossbeam, and the lower crossbeam form a multi-hinge closed chain. Starting from the single end observation at the cutting edge, the clearance contribution of each intermediate hinge cannot be uniquely decomposed, and the backlash at the same end can be generated by the combination of multiple intermediate clearances. If the outer surface contour of the lower crossbeam end or the tie rod end is separately cut in the same laser plane, the pose backlash at that point can be obtained in the same way, thus dividing the equivalent mechanism play into two segments before and after the hinge point. This embodiment does not perform a more detailed decomposition.

[0047] The angular components of the blades relative to each other at the corresponding measuring points on the left and right lobes are taken, and the difference between the relative angular components of the two lobes is obtained. This difference is obtained during the closing and opening strokes, and its variation with the opening degree is examined.

[0048] The component of the difference that has the same sign in both strokes and changes monotonically with the opening is taken as the asynchronous quantity. This component is an equivalent observation of asynchronousity, which can be caused by differences in tie rod length, rope system differences, or assembly deviations, and cannot be attributed solely to a single end observation.

[0049] The components with opposite signs in the two strokes of the difference are labeled as friction and guide resistance components. This component characterizes the motion direction-related response and can be caused by friction, guide resistance, commutation hysteresis, or control hysteresis; the sole source of the fault is uncertain. This component is not included in the asynchronous quantity and is only used for labeling output.

[0050] The set of mechanical deviations consists of the representative value of the equivalent mechanism play, the set of values ​​of the equivalent mechanism play in the direction of action, and the asynchronous quantities. Friction and guide resistance components are stored separately and are not included in the set of mechanical deviations.

[0051] Furthermore, referring to Figure 3 The wedge surface extension edge offset of the calibration measurement point includes: correcting the relative pose of the left and right lobes of the cutting edge with the equivalent mechanical clearance and asynchronous timing of the concentrated mechanical deviation, reducing the left and right lobes to the same reference configuration, and obtaining the relative pose of the two lobes. The two halves are brought to close in a jog manner, and the motion amount of the closing drive and the relative pose of the two halves are recorded step by step. The rate of change of the relative pose of the two halves with the motion amount is taken. The halves have only one rotational degree of freedom about the hinge axis relative to the halves. The position with the largest remaining height along the blade line first forms the mating contact and constitutes the mechanical stop. After the mating contact is formed, the motion amount is converted into structural elastic deformation and shaft hole clearance consumption, and the rate of change decreases. Take the position where the rate of change decreases as the inflection point, and take the measuring point where the inflection point is located as the contact measuring point; retract the two halves and repeat the jogging closure once. If the two inflection point positions are consistent, mark them as candidate mating contact; if they are inconsistent, mark them as uncertain stop. Clean the cutting edge area and jog again. The relative pose of the two lobes at the moment of contact determines that the edge gap at the contact measurement point is zero. The difference between the edge position under the zero gap condition and the intersection point obtained by the extension of the inner wedge surface and the outer wedge surface of the blade at the same moment is the wedge surface extension edge offset. The wedge surface extension edge offset corresponds to the passivation geometry of the edge. After obtaining the wedge-side extension edge offset, stop jogging and retract. The mating contact occurs only once in a single measurement, and the closing drive is not loaded to the working value.

[0052] Specifically, the relative poses of the cutting edges of the left and right lobes are corrected using the equivalent mechanical play and lag caused by the concentration of mechanical deviations: the equivalent mechanical play is subtracted from the relative poses of the cutting edges according to its direction of action, and the lag is subtracted from the difference in the relative rotation angles of the two lobes. The corrected poses of the left and right lobes are in the same reference configuration, and the difference between the two is called the relative poses of the two lobes. The relative poses of the two lobes have already deducted the quantified equivalent mechanical play and lag; unobserved elasticity, friction, and hysteresis are included in the pose uncertainty.

[0053] The two lobes are brought together and closed in a jogging motion. Each jogging step is set to the minimum value that allows the change in the relative pose of the two lobes to be stably resolved. The motion amount of the closing drive and the relative pose of the two lobes in the stable state after each step are recorded, resulting in a curve showing the change in the relative pose of the two lobes as a function of the motion amount.

[0054] Piecewise linear fitting is performed on the above curve: starting from the curve's starting point, the fitting segment is gradually expanded until the fitting residual exceeds a limit, at which point it is considered a segment. Then, expansion continues from the break point, resulting in several straight lines and their respective slopes. Candidate inflection points are selected where the ratio of the slopes of two adjacent segments is lower than the slope ratio limit. The slope ratio limit is determined by the fluctuation bandwidth of the slopes of each segmented straight line within the non-contact interval between the two halves, and is taken as the ratio of the lower bound of the fluctuation bandwidth to the mean.

[0055] Candidate inflection points are further confirmed using the baseline method. The slopes of several steps preceding the candidate inflection point are taken, and their mean and fluctuation bandwidth are calculated. When the two halves are not in contact, the elastic elongation of the closed wire rope and the friction of the pulley system cause the slope to fluctuate with the amount of motion; the slope is not a constant value, and a decrease in slope for a single step is insufficient to determine contact. When the slopes of several consecutive steps following the candidate inflection point are all below the lower bound obtained by subtracting the fluctuation bandwidth from the mean, the inflection point is confirmed. The measuring point where the inflection point is located is taken as the contact measuring point, that is, the measuring point where the slope first decreases in the moving step distance at that point.

[0056] The physical basis for the inflection point is as follows: the blade has only one rotational degree of freedom about the hinge axis relative to the blade body. The position with the greatest remaining height along the cutting edge first forms contact and constitutes a mechanical stop. Before contact is formed, the motion of the closing drive is almost entirely converted into configurational changes, with a relatively large slope. After contact is formed, the motion is converted into structural elastic deformation and the consumption of shaft-hole clearance, and the configurational changes slow down, with a decrease in slope. This criterion is not based on optical readings at the cutting edge, thus avoiding the breakage of the light stripe at sharp edges and center drift.

[0057] Return both lobes to their pre-contact opening position, repeat the jog closure once, and identify the inflection point again. If the difference in pose between the two inflection points does not exceed the limit, mark it as a candidate contact; if it exceeds the limit, mark it as an uncertain stop and clean and retest. Consistency between the two tests only indicates repeatability; candidate contacts must also be free of coarse or fine pick-off anomalies, and the difference in pose between the inflection points before and after cleaning must not exceed the limit; otherwise, terminate the offset calibration. Figure 3 This is an illustration of the initial screening, where "actual contact" refers to candidate contact; actual confirmation requires further verification through the aforementioned cleaning and contour anomaly checks. The contact repeatability limit is determined by the dispersion of the inflection point pose obtained by repeatedly performing a jog closure after material removal, and the upper statistical quantile is taken.

[0058] By determining the relative pose of the two lobes at the moment of contact, the gap between the two cutting edges at the contact measuring point is zero, thus obtaining the true position of the cutting edge at that moment. Simultaneously, the inner and outer wedge surfaces of the measuring point are extended and intersected to obtain the position of the wedge surface extension intersection point. The difference between the true cutting edge position and the wedge surface extension intersection point is taken as the wedge surface extension cutting edge offset at the contact measuring point. This offset corresponds to the passivation geometry of the cutting edge, i.e., the cutting edge changes from an ideal sharp angle to a transition surface with a certain passivation radius due to wear, causing the actual engagement position to lag behind the theoretical intersection point of the two wedge surfaces.

[0059] Once the bias is achieved, immediately stop the jogging and retract both blades. The contact occurs only once in a single measurement, and it is not required that the contact extend along the blade line; the blade has only one rotational degree of freedom relative to the bucket body, and a single point of contact forms a stop. If it is required that the contact extend to both sides, a closing force sufficient to cause millimeter-level elastic deformation in a welded structure weighing several tons must be applied. This method does not require this, and the closing drive is never loaded to the working value, so the blade is not damaged.

[0060] Furthermore, the virtual original contour is extended and constructed, including: selecting fitting sections of the inner wedge surface and the outer wedge surface of the blade for each positioning section, avoiding the passivation transition area of ​​the blade edge and the weld area at the root of the wedge surface, and shrinking the fitting section segment by segment with the fitting residual not exceeding the limit value to eliminate the interference of the surface undulation of the weld overlay on the wedge surface direction. For the fitted section, the inner wedge surface and the outer wedge surface of the fitted blade are extended towards the edge direction to find their intersection, obtaining the wedge surface extension intersection points of each return section; the position of each wedge surface extension intersection point in the body coordinate system of the blade forms the intersection point envelope; only within the same service cycle after the most recent blade replacement or welding and surface cleaning, the contour points that exceed the intersection point envelope and are isolated and protruding are treated as attached material or spatter and removed; after removal, the inner wedge surface and the outer wedge surface of the blade are refitted and the intersection is re-found; After re-intersectioning, compare the forward extension positions of the wedge surface extension intersection points of each repositioned section along the wedge surface normal, and take the section with the largest forward extension position as the minimum wear section; The wedge angle and wedge orientation of the minimum wear section are extended along the cutting edge. During the extension process, the wedge angle is kept constant according to the arc direction of the cutting edge, and the wedge orientation is kept to change continuously with the direction of the cutting edge, so as to obtain the virtual original contour of the cutting edge in the current repair state. The virtual original contour referred to in this embodiment is the reference contour used for this relative comparison in the current repair state, and does not represent the original contour of the new part from the factory.

[0061] Specifically, for each alignment section, fitting segments are selected on both the inner and outer wedge surfaces. The front end of the fitting segment avoids the passivation transition zone of the cutting edge, and the rear end avoids the weld zone at the root of the wedge surface. The positions of these two points are determined by the inflection points of the profile. After selection, a least-squares linear fit is performed on the segment, and the fitting residual is calculated. If the residual exceeds the wedge surface fitting residual limit, one endpoint is removed from each end of the segment, and the fit is repeated. This process is repeated until the residual does not exceed the limit. The surface of the weld overlay repair layer has weld bead undulations. The repeated shrinking ensures that the fitting segment is within a range with smaller undulations, avoiding the weld bead undulations from altering the estimation of the wedge surface orientation. The wedge surface fitting residual limit is determined by taking a spare segmented cutting plate that has not been put into service, collecting and fitting data at the same measurement station, statistically analyzing the distribution of its fitting residuals, and taking the upper statistical quantile of this distribution.

[0062] First, perform rough removal: Identify contour points where the echo intensity is below the rough removal strength limit, and contour points where the inflection point of the contour's normal direction exceeds the rough removal normal limit. These are identified as adhering material or weld spatter and removed. Coal powder and slurry adhering layers have loose surfaces and weak diffuse reflection, resulting in low echo intensity; spatter appears as isolated protrusions, hence abrupt changes in the normal direction. Rough removal strength and rough removal normal limits: At the same measurement station, collect cross-sectional contours of clean segmented cutting edges and segmented cutting edges with artificially adhered coal powder, respectively. Statistically calculate the range of echo intensity and contour normal inflection point values ​​for both sets, and determine the boundary between the two ranges.

[0063] After rough chipping, the inner and outer wedge surfaces are fitted according to step one, and the intersection is obtained by extending them towards the cutting edge direction to obtain the wedge surface extension intersection points of each positioning section. The positions of the wedge surface extension intersection points of all measuring points in the body coordinate system of the lobes are taken to form the intersection point envelope. Then, fine chipping is performed: the contour points that extend beyond the intersection point envelope, that is, those located further forward of the wedge surface extension intersection points, are identified as adhering material or weld spatter and removed. Fine chipping only deletes protruding points that extend beyond the envelope, are discontinuous with adjacent sections, and have abnormal characteristics of rough chipping; the continuous weld overlay layer formed in the most recent repair is retained as the current existing geometry.

[0064] The refined contour is refitted with inner and outer wedge surfaces, and the intersection is re-established, updating the intersection envelope. This refining and updating process is repeated until the change in the intersection envelope between two adjacent iterations does not exceed the envelope convergence limit. The order of coarse refining followed by fine refining ensures that the starting point of the iteration is not severely contaminated by attached material, avoiding non-convergence caused by using contaminated fitting results to remove contamination sources. The envelope convergence limit is set to the same order of magnitude as the wedge surface fitting residual limit.

[0065] After the iteration terminates, the coordinates of the intersection points of the extended wedge surfaces at each return section along the wedge surface normal towards the cutting edge are compared; these are the forward extension positions. The section with the largest forward extension position is taken as the section with the least wear. The forward extension position of the intersection point of the extended wedge surfaces is monotonically determined by the amount of remaining material in the segmented cutting plate at that section. The more remaining material, the further forward the intersection point. Therefore, the section with the largest forward extension position has the least material loss. This criterion is given by the measurement data itself and does not rely on the empirical assumption that the wear at the edge of the cutting edge is the least. Under conditions of off-center grabbing and single-sided wall cleaning, the grab bucket will experience off-center wear at the edge, and the edge is not necessarily the point of least wear.

[0066] The wedge angle of the section with the least wear is determined, which is the angle between the fitted straight lines of the inner and outer wedge surfaces, as well as the orientation of the two wedge surfaces. The extension proceeds along the cutting edge direction: the wedge angle remains constant during the extension process, and the orientation of the wedge surfaces continuously changes with the arc of the cutting edge. That is, the orientation of the wedge surfaces at each section is determined by the relationship between the tangent of the cutting edge at that section and the coordinate system of the blade body. The set of wedge contours obtained from the extension is the virtual original contour of the segmented cutting edge in its current repair state.

[0067] The virtual original profile is derived from the geometry of the segmented cutting edge itself, not from the design drawings or previous measurement results. The segmented cutting edge is a cast or welded part, and manufacturing deviations exist between individuals; furthermore, the cutting edge undergoes multiple weld repairs during its lifespan, and the actual profile after repair has permanently deviated from the design drawings. This method avoids applying the design drawings directly, but does not assume that manufacturing differences or repair excess height have been completely eliminated; absolute comparison is performed using the spare cutting edge and the qualified root section from Example 2.

[0068] Further, the cutting edge wear amount is obtained by: correcting the wedge surface extension intersection point of the contact measuring point with the wedge surface extension edge offset to obtain the functional cutting edge of the contact measuring point; taking the change of the wedge angle and wedge surface extension intersection point of each measuring point relative to the wedge angle and wedge surface extension intersection point of the contact measuring point, and extrapolating the wedge surface extension edge offset to each measuring point according to the change to obtain the functional cutting edge of each measuring point; the passivation geometry of the cutting edge changes continuously with the material residue at each position of the cutting edge, and the extrapolation replaces the equal translation of the wedge surface extension edge offset along the cutting edge. The amount of backlash of the functional edge relative to the virtual original contour along the wedge surface normal at each measuring point, together with the amount of cross-section loss, constitutes the edge wear amount. The edge wear amount distribution is obtained by arranging the measuring points along the edge line. Verify the measurement point at the minimum wear section and the contact measurement point: if the two measurement points coincide, it is confirmed that the blade wear distribution is valid; if the two measurement points do not coincide, it is determined that there is residual material at the contact measurement point or local chipping at the minimum wear section. Remove the material from the corresponding blade section and re-collect the data. Substituting the edge wear distribution and the set of mechanical deviations into the closed configuration, the fit line gap distribution is obtained. The fit line gap is then decomposed into the contribution of edge material loss, the contribution of equivalent mechanical play, and the contribution of asynchronous movement. When the edge material loss contribution exceeds the limit, a signal is output to repair welding or replace the edge. When the equivalent mechanical play contribution exceeds the limit, a signal is output to replace the pin and bushing. When the asynchronous movement contribution exceeds the limit, a signal is output to adjust the length of the tie rod.

[0069] Specifically, the intersection of the wedge-extended edge of the contact measuring point is corrected by the wedge-extended edge offset. The resulting position is the functional edge of the contact measuring point, that is, the edge position that actually participates in the engagement of the two halves.

[0070] The passivation geometry of the cutting edge is determined by the wedge angle and the amount of remaining material at that point, and it changes continuously with each position along the cutting line. Therefore, the offset of the wedge-extended cutting edge varies point by point, and the offset of the contact measuring point cannot be uniformly translated along the cutting line to other measuring points. The intersection of the wedge angle and the wedge-extended edge at each measuring point is compared with the intersection of the wedge angle and the wedge-extended edge at the contact measuring point to obtain the changes in the wedge angle and the forward extension position of the intersection point. The offset is extrapolated based on these two changes: the smaller the wedge angle, the longer the passivation transition zone unfolds in the normal direction of the wedge surface, and the larger the offset; the further back the forward extension position of the intersection point, the less remaining material, the larger the passivation radius, and the larger the offset. The extrapolation relationship is calibrated using a spare cutting edge of the same specification: the wedge angle, the forward extension position of the intersection point, and the actual cutting edge position measured by contact are recorded to form an offset lookup table; interpolation is performed between adjacent intervals for the target measuring point, and extrapolation is stopped if the value exceeds the range or if chipping occurs.

[0071] The retreat distance is the edge retraction amount, expressed in millimeters; the area enclosed within the return section is the section loss amount, expressed in square millimeters. These two constitute a set of wear parameters, which are arranged and compared separately, and not directly synthesized.

[0072] The initial contact depends on the joint gap between the two lobes. The minimum wear section only indicates the forward extension position of a single lobe, and the two do not necessarily coincide. When they coincide, it serves as evidence of consistency; when they do not coincide, check for adhesion, chipping, opposite high points, pose error, and elastic deformation. If they still do not coincide after retesting, the output is terminated.

[0073] Substituting the edge wear distribution and the set of mechanical deviations into the geometric relationship of the grab bucket closed chain in a fully closed configuration: using the virtual original contour as a reference, first, the two blade edges are moved back according to the edge wear distribution; then, the two blades are offset relative to each other along the direction of the equivalent mechanical play; finally, the two blades are deflected relative to each other around the closed axis according to the asynchronous movement. The distance between the two blade edges along the blade line is the meshing line gap distribution. Applying the above three terms individually and setting the other two terms to zero yields the contributions of blade material loss, equivalent mechanical play, and asynchronous movement in the meshing line gap. This decomposition is a decomposition of geometric quantities under the same configuration.

[0074] When the three types of contributions exceed their limits, maintenance prompts and shutdown interlock requests are output separately, without directly starting the welding repair equipment. After the grab bucket is stabilized, the drive is isolated, and manual confirmation is received, the external control system performs welding repair, replacement, or adjustment. The three types of signals are not confused to avoid repeated welding of the blade plate when the play exceeds the limit, or repeated replacement of the pin shaft when the blade plate wear exceeds the limit. The blade edge retraction limit and the cross-sectional missing area limit are determined by the strength check of the remaining height and remaining cross-section of the segmented blade plate, respectively, and are only compared with parameters of the same dimension. The play limit is determined by the fit tolerance between the pin shaft and the shaft hole and the scrap play given by the grab bucket manufacturer, and the smaller of the two values ​​is taken. The asynchronous limit is obtained by converting the allowable difference between the center distances of the two tie rods given by the grab bucket manufacturer to the blade line according to the geometric relationship of the closed configuration.

[0075] Example 2: The measured object, measurement station layout, sensor configuration, and data organization method in this embodiment are the same as in Embodiment 1, and will not be repeated. The content fully described in Embodiment 1 is only briefly described in this embodiment: the reference orientation of the bucket body and the orientation of the blade are obtained from the same cross-sectional profile, and the relative pose of the blade is obtained by subtracting the two; the actual hinge axis is obtained by intersecting the perpendicular bisectors of the displacement vectors of each measuring point between adjacent openings, and the bucket body coordinate system is established and the return section is generated accordingly; the equivalent mechanism backlash is obtained by the pose difference between the closed stroke and the opening stroke, and the asynchronous synchrotron is obtained by the component with the same sign in the forward and reverse strokes in the difference between the relative rotation angles of the two lobes; the first engagement contact is determined by the slope inflection point of the jog closed curve, and the wedge surface extension edge offset is calibrated accordingly; a virtual original profile is constructed by wedge surface fitting, iterative elimination, and minimum wear section extension; the edge wear is obtained by the difference between the functional edge and the virtual original profile, and is verified and attributed.

[0076] Based on this, this embodiment records the three-level reference chain, the self-built original wedge angle of the root segment of the same cross section, and the gap decomposition and cross-item verification of five sources.

[0077] Furthermore, the set of structural deviations also includes deviations at the separation blade mounting interface: Within the same cross section perpendicular to the hinge axis, a profile obtained by laser triangulation is used to separately cut the outer surface of the blade mounting seat between the bucket body profile and the blade profile. The blade mounting seat is the base material structure for the bucket petal leading edge to support the segmented blades. It is located outside the mounting and contacting surface on the back side of the segmented blades and extends continuously along the blade line direction. The area covered by the segmented blades does not contact the material, and there is an exposed part outside the covered area that can be cut by the laser plane. When the outer surface of the blade mounting seat is blocked by the opposite bucket petal and the number of effective points is lower than the limit of the effective point number of the profile, the benchmark connection is completed by comparing the overlap opening before the blocking occurs. The orientation of the bucket petal structure is determined by the contour segment corresponding to the outer surface of the blade mounting base. The position component and rotation component of the bucket petal structure orientation relative to the bucket body reference orientation are taken as the relative pose of the bucket petal. The position component and rotation component of the blade orientation relative to the bucket petal structure orientation are taken as the blade mounting pose. When the closed stroke and the open stroke pass through the same opening degree, the relative positions of the two petals are taken respectively, and the difference between the two is the equivalent mechanism play; the baseline of the blade plate installation position after re-tightening is recorded; subsequently, under the same opening degree, the same stroke direction and the same stopping condition, the difference with the baseline is calculated to obtain the installation looseness; The relative pose baseline of the bucket petals is recorded synchronously; the deformation of the mounting base is obtained by subtracting the relative pose of the bucket petals with the same opening from the baseline. The set of mechanical deviations is composed of the representative value of the equivalent mechanism play, the value of the equivalent mechanism play in the direction of action, the asynchronous amount, the amount of installation loosening, and the amount of deformation of the mounting seat.

[0078] Specifically, the base material structure of the segmented cutting edge receiving the leading edge of the bucket is the cutting edge mounting seat, located outside the mounting and contacting surface on the back side of the segmented cutting edge, extending continuously along the cutting line direction. The covered area does not contact the coal, and the visible exposed part outside the covered area is used as a reference after the overlap opening consistency test. The attitude of the sensor incident from above the outside of the bucket is adjusted so that the laser plane extends backward while covering the outer wedge surface of the cutting edge, covering the exposed part of the outer surface of the cutting edge mounting seat outside the segmented cutting edge. The same cross-sectional profile from one side of the bucket body towards the cutting edge direction successively includes the outer surface section of the bucket body side plate, the outer surface section of the hinge seat, the outer surface section of the cutting edge mounting seat, the exposed section of the mounting and contacting surface on the back side of the cutting edge, the outer wedge surface section of the cutting edge, and the inner wedge surface section of the cutting edge.

[0079] Least-squares linear fitting is performed on the outer surface segment of the blade mounting base, and its direction and distance to the sensor reference point are taken to determine the orientation of the bucket lobe structure. The positional and angular components of the bucket lobe structure orientation relative to the bucket body reference orientation are taken as the relative pose of the bucket lobe. This quantity reflects the overall movement of the bucket lobe relative to the bucket body, including the total clearance contribution of the hinge joint. The positional and angular components of the blade orientation relative to the bucket lobe structure orientation are taken as the blade mounting pose. This quantity only reflects the movement of the segmented blade relative to its mounting base, including the total clearance contribution of the fastening interface. The two-level difference is compounded step by step according to the reference chain order, which is consistent with the single-level difference in Example 1: during compounding, the positional component in the blade mounting pose is first transformed according to the coordinates of the angular component in the relative pose of the bucket lobe, and then added to the positional component in the relative pose of the bucket lobe. The angular component is added directly. The grading of the reference chain does not change the original values, but only separates the two types of deviations that were originally combined.

[0080] When the blade plate rotates into the inner side of the closed interval, the outer surface section of the blade plate mounting seat and the exposed section of the mounting mating surface are both blocked by the opposite blade plate. When the number of effective points on the outer surface section of the blade plate mounting seat is lower than the limit of the number of effective points on the contour, the angular component given by the orientation of the blade plate structure is compared with the angular component given by the arc fitting of the outer surface of the hinge seat at several overlapping openings before the blocking occurs. If the difference does not exceed the angular consistency limit, the position component of the orientation of the blade plate structure is continued from the outer surface of the hinge seat within the blocking opening interval. The angular component uses the value of the last opening before the blocking occurs and is extrapolated according to the geometric relationship of the blade plate rotating around the actual hinge axis. The hinge seat is located at the center of rotation, and its angular resolution is lower than that of the mounting seat extending along the blade line. Therefore, the angular component is not directly given by the hinge seat. The blocking extrapolation is only used when the overlap opening consistency test is passed; if it fails, the separation of the installation interface deviation is terminated, and the installation looseness is not inferred from the difference in forward and reverse strokes.

[0081] After re-tightening, the blade mounting posture is captured at the preset opening and stabilized as a baseline. Subsequent measurements are taken using the same opening, stroke direction, and stabilization conditions. The change in the current posture relative to the baseline is converted to the blade line as the installation loosening amount. If the difference between forward and reverse strokes exceeds the limit, re-sampling is performed; a reversal of the motion direction is not interpreted as a reversal of the gravity direction.

[0082] The baseline measurement synchronously records the relative pose of the lobes at each preset opening degree. The constant difference between the baseline and the measured value under the same opening degree and stationary conditions is used as the deformation of the mounting base; if the difference changes irregularly or repeatedly exceeds the limit, the measurement is repeated. Manufacturing and assembly deviations are eliminated by subtracting from the baseline.

[0083] The equivalent mechanism play, the equivalent mechanism play with respect to the direction of action, the asynchronous amount, the installation looseness, and the deformation of the mounting base together constitute the set of mechanism deviations. The equivalent mechanism play is then given by the difference in forward and reverse strokes of the relative positions of the bucket segments, and no longer includes the mounting interface component.

[0084] Furthermore, the extension and construction of the virtual original contour also includes the creation of a custom original wedge angle: By comparing the profiles of the spare segmented cutting edge plates that are not yet in service with those of the segmented cutting edge plates in service, the starting point of the material shearing path is taken as the point where the two begin to deviate. For each positioning section, a root section and a front section are selected on the inner wedge surface and the outer wedge surface of the cutting edge plate, respectively. The root section is located between the installation edge and the starting point of the material shearing path, and the front section is located between the starting point of the material shearing path and the edge passivation transition zone. The wedge angles given at the root section of each measuring point are subject to two judgments: the difference between each measuring point does not exceed the root consistency limit, and the difference between the wedge angle at each measuring point and the wedge angle measured by the spare segmented cutting plate does not exceed the root absolute limit; if both judgments are satisfied, the root section is determined to be unworn, and the wedge angle and wedge surface orientation given at the root section are taken as the original wedge surface; if either judgment is not satisfied, the root section is determined to be worn, and the wedge angle and wedge surface orientation measured by the spare segmented cutting plate are taken as the original wedge surface. For the same cross section, take the amount of retreat of the given wedge surface at the front end relative to the original wedge surface along their respective normal directions, and obtain the retreat of the inner wedge surface and the retreat of the outer wedge surface respectively. The wear vector direction and the degree of uneven wear are obtained according to the normal projection constraint of the two wedge surfaces. A virtual original contour is constructed by extending the original wedge surface along the cutting edge. The wedge angles given by the original wedge surface of each section are checked for consistency with the wedge angles given by the minimum wear section. If the difference exceeds the root consistency limit, the wedge angles given by the original wedge surface shall prevail.

[0085] Specifically, a spare segmented cutting edge plate that is not yet in service is taken, and its cross-sectional profile is repeatedly sampled several times at the same measurement station in the same manner. The dispersion of its cross-sectional profile is statistically analyzed, and its average profile is used as the original morphology reference. The profile of the returned cross-section of the in-service segmented cutting edge plate and the corresponding cross-sectional profile of the spare segmented cutting edge plate are aligned in the coordinate system of the blade body and compared. The cross-section is scanned from the installation side towards the cutting edge. The point where the deviation between the two exceeds the upper statistical quantile of the above dispersion is the starting position of the material shearing path. The section within this position does not slip relative to the coal during the gripping process, while the section outside this position is subjected to abrasive wear.

[0086] For each return section, two segments are divided on both the inner and outer wedge surfaces of the cutting edge: the root segment is located between the mounting edge and the starting position of the material shearing path, and the front segment is located between the starting position of the material shearing path and the edge passivation transition zone. The two segments are fitted using the successive shrinkage method described in Example 1 until the fitting residual does not exceed the wedge surface fitting residual limit.

[0087] The root section undergoes two-stage judgment. The first stage is a relative judgment: the wedge angles given at each measuring point are compared, and the difference between the measuring points is passed if the difference does not exceed the root consistency limit. The second stage is an absolute judgment: the wedge angles given at each measuring point are compared with the wedge angles measured by the spare segmented cutting edge; the difference is passed if the absolute root limit is not exceeded. When both judgments are satisfied, the root section is determined to be unworn, and the wedge angles and wedge surface orientation given at the root section are taken as the original wedge surface. It is assumed that the relative judgment alone may result in a missed judgment: if the root sections at all measuring points along the entire cutting edge have similar degrees of wear, and the wedge angle difference between the measuring points is still less than the limit, the relative judgment will not be triggered. If either judgment is not satisfied, the root section is determined to be worn, and the wedge angles and wedge surface orientation measured by the spare segmented cutting edge are taken as the original wedge surface. The absolute root limit is determined by the dispersion of the wedge angles obtained from repeated measurements at the same measuring station using a spare segmented cutting edge that has not yet been put into service; the upper statistical quantile of this dispersion is taken.

[0088] For the same cross-section, the recoil of the inner wedge surface relative to the original inner wedge surface along the normal direction of the inner wedge surface is taken, along with the recoil of the outer wedge surface relative to the original outer wedge surface along the normal direction of the outer wedge surface. During grabbing, the coal flows inward along the inner surface of the bucket, and the relative slippage experienced by the inner wedge surface is stronger than that of the outer wedge surface. The two recoil amounts are generally not equal. The recoil amount is used as the projection of the wear displacement onto the normal directions of the two wedge surfaces, and two projection constraints are solved; the displacement direction is the wear vector direction, and the ratio of the recoil amounts is the degree of uneven wear. When the two normal directions are approximately parallel or the solution sensitivity exceeds the limit, the marked cross-section is invalid and re-sampled. The wear vector direction is determined by the relative proportion of material removed from the two wedge surfaces and does not characterize the actual slippage direction of the coal.

[0089] The original wedge surface is extended along the cutting edge, maintaining a constant wedge angle and ensuring the wedge surface orientation continuously changes with the arc of the cutting edge to obtain a virtual original contour. The wedge angles given by the original wedge surface of each section are compared with the wedge angles given by the minimum wear section in Example 1: when the difference does not exceed the root consistency limit, the two paths corroborate each other; when the limit is exceeded, the wedge angle given by the original wedge surface is taken as the standard, because the wedge angle of the minimum wear section has been changed under the condition of unilateral wear along the entire cutting edge, while the root section does not participate in material shearing and the wedge angle remains in its original state.

[0090] Furthermore, obtaining the cutting edge wear amount also includes: The wear vector direction is used instead of the single wedge surface normal. The amount of backward movement of the functional edge relative to the virtual original contour along the wear vector direction is taken as the edge wear amount. The wear vector direction is not derived by the line connecting the intersection of the functional edge and the virtual original contour. Substituting the edge wear distribution, wear vector direction, and mechanical deviation set into the geometric relationship of the closed configuration, and applying each item individually while setting the others to zero, the contributions of the blade material loss, equivalent mechanical clearance, asynchronous timing, installation looseness, and mounting deformation in the mating line gap are obtained respectively. The difference between the mating line gap obtained by applying the five items together and the sum of the five contributions is output as the cross term residual. If the cross term residual exceeds the cross term limit, the decomposition is determined to be invalid and the data is collected again. When the contribution of installation loosening exceeds the installation loosening limit, the output control signal stops the grab bucket from being put into operation and indicates that the segmented blade plate should be tightened; when the contribution of mounting base deformation exceeds the mounting base deformation limit, the output control signal stops the grab bucket from being put into operation and indicates that the mounting base should be repaired; when the wear vector direction deviates from the normal plane of the blade line by more than the eccentric wear limit, the measuring point is marked as eccentric wear and output along with the blade wear distribution.

[0091] The wear vector direction is used instead of the single wedge surface normal. The amount of retraction of the functional cutting edge relative to the virtual original contour along the wear vector direction is taken as the cutting edge wear amount. The wear vector direction is the result of the synthesis of the retraction amounts of the free inner and outer wedge surfaces, and is not derived by connecting the intersection of the functional cutting edge and the virtual original contour. The order of the two cannot be reversed.

[0092] The distribution of edge wear, the direction of the wear vector, and the set of mechanical deviations are all substituted into the geometric relationship of the grab bucket closed chain in a fully closed configuration. Starting from the virtual original contour, the contributions of edge material loss, equivalent mechanical clearance, asynchronous quantity, installation looseness, and mounting deformation in the gap between the mating lines are obtained by applying each item individually and setting the rest to zero.

[0093] Material loss, equivalent mechanism clearance, installation looseness, and mounting bracket deformation are translational quantities, while asynchronous quantities are angular quantities. Angular quantities produce different displacements at different positions along the cutting edge. The effects of these five items on the mating line gap are not strictly linear and can be additive. The mating line gap obtained by applying all five items is subtracted from the sum of their contributions, and the difference is output as the cross-term residual. If the cross-term residual does not exceed the cross-term limit, the decomposition is confirmed; if it exceeds the limit, the decomposition is deemed invalid, and data is collected again. Each contribution is first converted to the gap length at the same cutting edge position. The cross-term limit is determined by the upper statistical quantile of the residuals obtained from repeated data collection under the same working condition, with the same unit as the mating line gap.

[0094] When any of the five contribution parameters exceed the limit, a shutdown interlock request and maintenance prompt will be output. After equipment isolation and manual confirmation, the external control system will handle the situation. When the wear vector direction deviates from the normal plane of the cutting edge by more than the wear deviation limit, the ratio of the deviation angle of the measuring point to the retraction of the inner and outer wedge surfaces will be output as the wear deviation state, given according to the distribution of the cutting edge wear, and will not be used as a drive command. The installation loosening limit is the allowable relative displacement converted to the cutting edge, and has the same dimension as the installation loosening amount; the preload attenuation value is only manually verified and is not directly compared with the displacement limit.

[0095] The deformation limit of the mounting base is determined by the strength check of the remaining section of the mounting base. The maximum indentation is taken when the stress of the remaining section under the rated closing force and rated impact load does not exceed the allowable stress of the mounting base material.

[0096] The wear limit is determined by the ratio of the retraction of the inner and outer wedge surfaces. This ratio is taken as the directional deviation angle when the displacement of the functional edge from the normal plane of the cutting edge reaches half of the gap limit of the mating line.

[0097] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-contact measurement method for the wear of a grab bucket cutting edge based on laser triangulation, characterized in that, include: Obtain the bucket body profile and blade profile in a section perpendicular to the hinge axis, and calculate the relative pose of the blade. The opening is defined by relative pose. The actual hinge axis is determined by the relative pose change of the measuring points distributed along the blade line on the opening of the closed interval. The body coordinate system of the lobes is established. Based on the relative pose of the closed stroke and the open stroke, the equivalent mechanism clearance referred to the cutting edge is obtained; the component with the same sign in the forward and reverse strokes in the difference between the relative rotation angles of the two lobes is taken as the asynchronous mechanism quantity; the equivalent mechanism clearance is combined to form the mechanism deviation set. The two lobes are reduced to the same reference configuration by the set of institutional deviations. The jog closure is performed and the rate of change of the relative pose of the two lobes with the driving action is monitored. The first engagement contact is determined by the inflection point of the rate of change. The relative pose at the moment of contact is used as the zero gap constraint to calibrate the wedge surface extension edge offset of the measuring point. Fit the inner and outer wedge surfaces of the repositioned section and extend to find the intersection. After eliminating points that exceed the envelope of the intersection point, refit the section. Take the section with the largest forward extension position of the intersection point as the minimum wear section and extend to construct a virtual original contour. Extrapolate the offset to each measuring point according to the wedge surface geometry to obtain the functional edge. Obtain the edge wear based on the functional edge and the virtual original contour.

2. The non-contact measurement method for the wear of a grab bucket cutting edge based on laser triangulation as described in claim 1, characterized in that: The calculation of the relative pose of the blade includes: in the same section perpendicular to the hinge axis, using laser triangulation to obtain the contour and simultaneously cutting the outer surface of the bucket body side plate, the outer surface of the hinge seat, the exposed section of the mounting and fitting surface on the back of the blade, the inner wedge surface of the blade, and the outer wedge surface of the blade; the reference orientation of the bucket body is determined by the direction of the two contours of the outer surface of the bucket body side plate and the outer surface of the hinge seat and the included angle between the two contours. The blade orientation is determined by the exposed section of the mounting surface on the back of the blade. When the bucket flap turns to the inside of the closed zone and the mounting surface on the back of the blade is blocked by the opposite bucket flap, the blade orientation is determined by the unworn section of the outer wedge surface of the blade near the mounting edge. The two blade orientations are connected at the overlapping opening before the blocking occurs. The position component and the rotation component of the blade orientation relative to the bucket body reference orientation are taken as the relative pose of the blade. Multiple frames of contour are collected at the same opening and the relative pose of the blade is averaged over time to suppress the fluctuation of the interception position caused by the change of the incident angle on the wedge surface due to the swing of the grab bucket suspension.

3. The non-contact measurement method for gripper blade wear based on laser triangulation as described in claim 2, characterized in that: Establishing a bifurcation body coordinate system includes: defining the opening using the rotation component in the relative pose; within the closed interval, causing the bifurcation to stop sequentially at adjacent openings, distributing measuring points along the cutting edge according to the position of the segmented cutting edge, with each measuring point providing the change in relative pose of the cutting edge between adjacent openings, and summing the changes in the measuring points along the cutting edge to form the displacement field of the same rigid body, with the spacing between the measuring points along the cutting edge constituting the baseline of the displacement field, and the baseline length bearing the solution constraint caused by the small displacement under small opening difference conditions; determining the actual hinge axis based on the displacement in the displacement field, establishing the bifurcation body coordinate system with the actual hinge axis as the axial reference and the orientation of the mounting and fitting surface on the back side of the cutting edge as the direction reference; and uniformly transforming the inner wedge surface profile and outer wedge surface profile of the cutting edge under each opening to the bifurcation body coordinate system to obtain the repositioning section.

4. The non-contact measurement method for gripper blade wear based on laser triangulation as described in claim 3, characterized in that: The set of structural deviations includes: within the closed interval, the bucket flaps complete the closing and opening strokes sequentially. During the closing stroke, the tie rod bears the closing driving tension, and during the opening stroke, the tie rod bears the reverse action of the bucket flaps' own weight. The pins are respectively attached to the opposite sides of the shaft hole during the two strokes. When the two strokes pass through the same opening degree, the relative poses of the blades are taken respectively. The difference between the relative poses of the two blades is taken as the equivalent structural clearance referred to the blade line. The direction of action of the equivalent structural clearance is determined by the projection of the tie rod axis in the cross section. The value is repeatedly taken at several opening degrees within the closed interval. The projection direction of the tie rod axis is different at each opening degree, thus obtaining the distribution of the equivalent structural clearance with the direction of action. The distribution of the equivalent structural clearance with the direction of action corresponds to the non-circular wear of the shaft hole. The difference in relative rotation angles between the corresponding measuring points on the left and right lobes is taken. The component of the difference in relative rotation angles with the same sign in the closing stroke and opening stroke, and which changes monotonically with the opening, is taken as the asynchronous quantity. The asynchronous quantity represents the stable asynchronous state of the two lobes' strokes. The component of the difference in relative rotation angles with opposite signs in the closing stroke and opening stroke is marked as the friction and guide resistance component. The equivalent mechanism play, the distribution of the equivalent mechanism play with the direction of action, and the asynchronous quantity constitute the mechanism deviation set.

5. The non-contact measurement method for gripper blade wear based on laser triangulation as described in claim 4, characterized in that: The wedge-surface extension of the calibration measurement point is offset by: correcting the relative pose of the left and right lobes of the cutting edge with the equivalent mechanical clearance and asynchronous amount of the concentrated mechanical deviation, reducing the left and right lobes to the same reference configuration, and obtaining the relative pose of the two lobes; closing the two lobes towards each other by jogging, recording the motion amount of the closing drive and the relative pose of the two lobes step by step, and taking the rate of change of the relative pose of the two lobes with the motion amount. The point where the rate of change decreases is taken as the inflection point, and the measuring point at the inflection point is taken as the contact measuring point. The two lobes are retracted and the jogging closure is repeated once. When the two inflection point poses are consistent, they are marked as candidate mating contact. When they are inconsistent, they are marked as uncertain stop. After cleaning the cutting edge area, the jogging is repeated. The relative poses of the two lobes at the moment of contact determine that the edge clearance at the contact measuring point is zero. The difference between the edge position under the zero clearance condition and the intersection point obtained by the extension of the inner wedge surface and the outer wedge surface of the cutting plate at the same moment is taken as the wedge surface extension edge offset. The wedge surface extension edge offset corresponds to the passivation geometry of the edge.

6. The non-contact measurement method for the wear of a grab bucket cutting edge based on laser triangulation as described in claim 5, characterized in that: The virtual original contour is constructed by extension, including: selecting fitting sections of the inner wedge surface and the outer wedge surface of the blade for the return section respectively; fitting the inner wedge surface and the outer wedge surface of the blade for the fitting section, extending and finding the intersection in the direction of the blade edge to obtain the wedge surface extension intersection point of each return section; using the position of each wedge surface extension intersection point in the coordinate system of the blade body to form the intersection point envelope, and only within the same service cycle after the most recent blade replacement or welding and surface cleaning, the contour points that exceed the intersection point envelope and are isolated and protruding are treated as attached material or spatter and removed. Compare the forward extension positions of the wedge surface extension intersection points of the repositioned section along the normal of the wedge surface after re-intersection, and take the section with the largest forward extension position as the minimum wear section; extend along the cutting edge with the wedge angle and wedge surface orientation of the minimum wear section, and keep the wedge angle constant and the wedge surface orientation continuously change with the cutting edge direction during the extension process to obtain the virtual original contour of the cutting edge in the current repair state.

7. The non-contact measurement method for gripper blade wear based on laser triangulation as described in claim 6, characterized in that: The method for obtaining the cutting edge wear amount includes: taking the change between the wedge angle and the intersection of the wedge surface extension of the measuring point and the wedge angle and the intersection of the wedge surface extension of the contact measuring point; pushing the wedge surface extension of the cutting edge outward to the measuring point according to the change to obtain the functional cutting edge of the measuring point; taking the amount of retreat of the functional cutting edge of the measuring point relative to the virtual original contour along the wedge surface normal and the amount of cross-section loss as the cutting edge wear amount; arranging the measuring points along the cutting edge line to obtain the cutting edge wear amount distribution. Verify the measurement point at the minimum wear section and the contact measurement point: if the two measurement points coincide, it is confirmed that the blade wear distribution is valid; if the two measurement points do not coincide, it is determined that there is residual material at the contact measurement point or local chipping at the minimum wear section. Remove the material from the corresponding blade section and re-collect the data. Substituting the edge wear distribution and the set of mechanical deviations into the closed configuration, we obtain the mating line gap distribution, and decompose the mating line gap into the contribution of blade material loss, the contribution of equivalent mechanical clearance, and the contribution of asynchronous clearance.

Images