A handheld three-probe planar parameter measurement method

Abstract

The present application relates to the technical field of plane geometry measurement, in particular to a hand-held three-probe plane parameter measurement method, comprising: first, mounting three probes on a hand-held support according to a fixed geometric baseline, synchronously collecting three groups of vertical distance data, combining the baseline parameters to construct a space plane equation, and solving the instantaneous attitude angle of the measured plane relative to the hand-held support; synchronously collecting three-axis inertial motion data of the hand-held support; after time stamp alignment of the two types of data, forming a fused attitude sequence; according to the sequence, inversely compensating the space displacement error to obtain a precise corrected distance value; statistically averaging a plurality of groups of corrected distance values obtained by continuous sampling; and finally outputting the measured flatness parameter. The method can complete plane attitude solving and data dynamic correction in a hand-held mobile operation state, effectively weaken the data fluctuation caused by hand-held operation, adapt to various flexible detection scenes, and improve the adaptability and data fitting degree of the actual measurement of plane parameters in a hand-held mode.

Description

Technical Field

[0001] This invention relates to the field of plane geometry measurement technology, and in particular to a handheld three-probe plane parameter measurement method. Background Technology

[0002] Currently, planar parameter detection generally employs single-point or dual-point ranging methods for data acquisition. Most measuring devices use fixed installation structures for data collection, and there is a lack of supporting testing methods for mobile handheld measurements. Existing measurement methods can only acquire distance information from a limited number of points and cannot rely on the acquired data to solve for the spatial attitude information of the measured plane in real time. The positional changes and angular deviations caused by the measurement vehicle being in motion cannot be effectively identified, and the original acquired data will deviate from the actual state due to the movement of the vehicle.

[0003] Existing data processing methods can only perform basic numerical integration calculations and cannot correct data for spatial position changes caused by the dynamic movement of the measurement vehicle. The detection data acquired in handheld measurement mode exhibits strong dispersion, and the consistency of continuously acquired data is low. Conventional measurement structures lack multi-point baseline layouts adapted for attitude calculation and do not establish data processing logic for mutual linkage and calibration between motion sensing data and ranging attitude data, making it difficult to meet the needs of mobile, rapid planar detection in variable field environments. The industry urgently needs a measurement method that can achieve autonomous attitude calculation based on a multi-probe layout and simultaneously perform autonomous data error correction by combining motion sensing information. This would improve the overall implementation conditions for planar parameter detection in handheld conditions and address the shortcomings of existing measurement technologies in dynamic detection. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a handheld three-probe planar parameter measurement method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a handheld three-probe planar parameter measurement method, comprising: Three probes are arranged and mounted on a handheld bracket according to a fixed geometric baseline. The vertical distance data between the three probes and the plane being measured is collected simultaneously to obtain three sets of real-time distance values. Based on the three sets of real-time distance values ​​and the fixed geometric baseline parameters of the three probes on the handheld bracket, a spatial plane equation with the three probes as reference points is constructed, and the instantaneous attitude angle of the measured plane relative to the handheld bracket is calculated. The three-axis inertial motion data of the handheld support during the measurement process are collected. The three-axis inertial motion data includes linear acceleration and angular velocity. After preprocessing the linear acceleration and angular velocity with different integration orders, the three-axis inertial motion data is timestamped with the instantaneous attitude angle to generate a fused attitude sequence. Based on the fused attitude sequence, the spatial displacement error of the handheld support at the sampling time is compensated in reverse to obtain the corrected distance value between the probe and the measured plane. The final flatness parameters of the measured plane are output by statistically averaging multiple corrected distance values ​​obtained within a continuous sampling period.

[0006] As a further aspect of the present invention, the steps of arranging and mounting three probes on a handheld bracket according to a fixed geometric baseline, and simultaneously collecting vertical distance data between the three probes and the plane being measured to obtain three sets of real-time distance values, specifically include: The three probes are respectively installed on the three fixed support points of the handheld bracket, so that the geometric lines connecting the three fixed support points form an isosceles triangle, and the side lengths of the three sides of the isosceles triangle are recorded as the fixed geometric baseline parameters. The synchronous triggering circuit of the three probes is activated, and the distance acquisition function of the three probes is activated simultaneously on the rising edge of the same clock pulse. Each probe transmits a measurement signal and receives the echo signal reflected back from the measured plane. Based on the time difference between the transmission time of the measurement signal and the reception time of the echo signal, the vertical distance from each of the three probes to the measured plane is calculated, and these three vertical distances are arranged in the order of the probe numbers to form the three sets of real-time distance values.

[0007] As a further aspect of the present invention, the step of constructing a spatial plane equation with the three probes as reference points based on the three sets of real-time distance values ​​and the fixed geometric baseline parameters of the three probes on the handheld bracket, and calculating the instantaneous attitude angle of the measured plane relative to the handheld bracket, specifically includes: A support coordinate system is established with the geometric center of the three fixed support points on the handheld bracket as the origin and the front direction of the handheld bracket as the normal direction. The installation position coordinates of the three probes are marked in the support coordinate system. The coordinates of each installation position are calculated from the fixed geometric baseline parameters. The three sets of real-time distance values ​​are respectively assigned to the installation position coordinates of the three corresponding probes, so that the installation position coordinates of each probe are moved along the normal direction of the bracket coordinate system by a distance equal to the real-time distance value of the probe, thereby obtaining the coordinates of three spatial points, which are located on the plane being measured. Based on the coordinates of the three spatial points, solve the unique spatial plane equation passing through these three spatial point coordinates. Extract the pitch angle and roll angle of the measured plane relative to the support coordinate system about the horizontal axis from the spatial plane equation. Combine the pitch angle and roll angle to form the instantaneous attitude angle.

[0008] As a further aspect of the present invention, the step of solving the unique spatial plane equation passing through the three spatial point coordinates, extracting the pitch angle and roll angle of the measured plane relative to the support coordinate system about the horizontal axis from the spatial plane equation, and combining the pitch angle and roll angle into the instantaneous attitude angle, specifically includes: The coordinates of the three spatial points are represented as the first spatial point coordinates, the second spatial point coordinates, and the third spatial point coordinates, respectively. The first direction vector is obtained by subtracting the second spatial point coordinates from the first spatial point coordinates, and the second direction vector is obtained by subtracting the third spatial point coordinates from the first spatial point coordinates. Calculate the cross product of the first direction vector and the second direction vector to obtain the normal vector of the measured plane. Divide the normal vector by its own magnitude to normalize it and obtain the unit normal vector. The original normal vector of the support coordinate system is denoted as a unit vector pointing in the positive direction. The angle between the unit normal vector and the original normal vector is calculated. The angle is decomposed into the horizontal and vertical axes of the support coordinate system to obtain the pitch angle and the roll angle. The pitch angle and the roll angle are combined to form the instantaneous attitude angle.

[0009] As a further aspect of the present invention, the steps of collecting three-axis inertial motion data of the handheld support during the measurement process, aligning the three-axis inertial motion data with the instantaneous attitude angles with timestamps, and generating a fused attitude sequence specifically include: A six-axis inertial measurement unit is installed inside the handheld bracket. The six-axis inertial measurement unit outputs the linear acceleration of the handheld bracket along the three orthogonal axes and the angular velocity of the rotation around the three orthogonal axes in real time. The linear acceleration and angular velocity are combined into the three-axis inertial motion data. A global timestamp is assigned to the three sets of real-time distance values ​​for each sampling, and an inertial timestamp is assigned to each output three-axis inertial motion data. The absolute difference between the inertial timestamp and the global timestamp is calculated, and a dynamic threshold for the absolute difference is set. The dynamic threshold is proportional to the rate of change of the instantaneous angular velocity of the handheld support between adjacent sampling times. Three-axis inertial motion data with a difference between the inertial timestamp and the global timestamp less than the preset threshold are selected from all three-axis inertial motion data. The selected three-axis inertial motion data are bound to the instantaneous attitude angle corresponding to the same global timestamp as a fusion record. All fusion records are arranged in chronological order of global timestamps to generate the fusion attitude sequence.

[0010] As a further aspect of the present invention, the step of reversely compensating for the spatial displacement error of the handheld support at the sampling time based on the fused attitude sequence to obtain the corrected distance value between the probe and the measured plane specifically includes: Extract the three-axis inertial motion data corresponding to the current sampling time from the fused attitude sequence, and perform a second time integration operation on the linear acceleration in the three-axis inertial motion data to obtain the three-dimensional displacement vector of the handheld support within the sampling time interval; Perform a time integration operation on the angular velocity in the three-axis inertial motion data to obtain the three-dimensional rotation vector of the handheld support within the sampling time interval. Superimpose the three-dimensional rotation vector with the instantaneous attitude angle at the current sampling moment to obtain the actual spatial attitude of the handheld support. Based on the three-dimensional displacement vector and the actual spatial posture, the offset of the handheld support relative to the reference position at the previous sampling time is calculated. The corrected distance value is obtained by subtracting the projection components of the reference position offset in the three probe directions from the three sets of real-time distance values.

[0011] As a further aspect of the present invention, the step of calculating the reference position offset of the handheld bracket relative to the previous sampling moment based on the three-dimensional displacement vector and the actual spatial posture, and subtracting the projection components of the reference position offset in the three probe directions from the three sets of real-time distance values ​​to obtain the corrected distance value, specifically includes: The three-dimensional displacement vector is decomposed into three orthogonal axes of the handheld bracket to obtain the displacement components along the horizontal axis, the displacement components along the vertical axis, and the displacement components along the normal direction. Based on the pitch and roll components in the actual spatial attitude, a rotation matrix is ​​constructed, and the displacement components along the horizontal axis and the displacement components along the vertical axis are projected onto the tangent direction of the measured plane through the rotation matrix to obtain the horizontal projection component and the vertical projection component. Based on the probe position corresponding to the minimum value among the three sets of real-time distance values, a weighting coefficient is dynamically determined. The displacement component along the normal direction is directly used as the normal projection component. After multiplying the normal projection component by the weighting coefficient, it is combined with the lateral projection component, longitudinal projection component, and normal projection component to form the reference position offset. The corresponding component of the reference position offset is subtracted from the three sets of real-time distance values ​​respectively, and the corrected distance value is output.

[0012] As a further embodiment of the present invention, the rotation matrix is ​​constructed in Euler angle form according to the rotation order prioritizing the horizontal axis.

[0013] As a further aspect of the present invention, the step of statistically averaging multiple corrected distance values ​​obtained within a continuous sampling period and outputting the final flatness parameter of the measured plane specifically includes: A continuous sliding time window is set, the length of which includes a fixed number of sampling periods. The length of the sliding time window is inversely proportional to the real-time movement speed of the handheld support. At the end of each sampling period, the three sets of corrected distance values ​​calculated within that sampling period are stored in the buffer corresponding to the sliding time window. Once the sliding time window is filled, the arithmetic mean is calculated for each set of corrected distance values ​​in the buffer to obtain the set of average corrected distance values. Then, the standard deviation is calculated for each set of corrected distance values ​​in the buffer to obtain the set of corrected distance value dispersion. The average corrected distance value set is used as the distance reference value of the measured plane, and the maximum value in the set of corrected distance value dispersion is used as the flatness error value of the measured plane. The distance reference value and the flatness error value are combined and output as the final flatness parameter.

[0014] As a further aspect of the present invention, the flatness error value is obtained by multiplying the maximum value in the set of dispersion of the corrected distance value by a preset scaling factor and adding a preset zero-point offset.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: Three probes are systematically deployed based on a fixed geometric baseline, simultaneously acquiring multiple sets of vertical distance data. Using the established baseline geometric parameters, corresponding spatial plane equations are constructed, enabling real-time calculation and processing of the attitude angles of the measured plane. This deployment method allows for the simultaneous acquisition of distance data and calculation of spatial attitude parameters, expanding the dimensions of planar information obtainable during measurement. It changes the traditional limited-point measurement mode, which only acquires distance values, by enriching the basic data required for planar spatial state-related calculations. This allows planar spatial orientation parameters to be directly derived from measured data, overcoming the limitations of limited-point structures in spatial attitude parameter calculations and perfecting the complete acquisition and calculation process for basic planar parameters.

[0016] By uniformly matching the triaxial inertial motion acquisition data with the calculated instantaneous attitude angles in the time dimension, a complete attitude data sequence with unified time sequence is formed. This integrated data sequence is then used to perform calculations to correct spatial displacement deviations caused by the motion of the measurement vehicle, completing the dynamic numerical adjustment of the original distance measurement data. This time-unified data fusion method enables synchronous correspondence between measurement actions and attitude calculation information, accurately matching the vehicle motion state corresponding to each set of sampled data. It systematically adjusts for data deviations caused by changes in vehicle position and angle during the measurement process, ensuring that distance data acquired at different sampling times remains stable. The resulting planar parameters, after averaging, closely match the actual state of the measured plane, adapting to mobile measurement operations without fixed support structures and broadening the scope of implementation scenarios for planar parameter measurement. Attached Figure Description

[0017] Figure 1 This is a state diagram of a handheld three-probe planar parameter measurement method according to the present invention; Figure 2 A flowchart illustrating the workflow for synchronously acquiring vertical distance data using three probes; Figure 3 A flowchart illustrating the process of obtaining a corrected distance value to compensate for spatial displacement errors of the handheld support. 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 merely illustrative and not intended to limit the invention.

[0019] See Figure 1 The present invention discloses a handheld three-probe planar parameter measurement method, which includes the following steps in specific implementation: Three probes are arranged and installed on a handheld support according to a fixed geometric baseline; vertical distance data between the three probes and the plane being measured are collected synchronously to obtain three sets of real-time distance values; based on the three sets of real-time distance values ​​and the fixed geometric baseline parameters of the three probes on the handheld support, a spatial plane equation is constructed with the three probes as reference points, and the instantaneous attitude angle of the plane being measured relative to the handheld support is calculated; three-axis inertial motion data of the handheld support are collected during the measurement process, and the three-axis inertial motion data is timestamped with the instantaneous attitude angle to generate a fused attitude sequence; based on the fused attitude sequence, the spatial displacement error of the handheld support at the sampling time is compensated in reverse to obtain the corrected distance value between the probes and the plane being measured; multiple corrected distance values ​​obtained within a continuous sampling period are statistically averaged to output the final flatness parameter of the plane being measured.

[0020] In one embodiment of the present invention, see [reference] Figure 2Three probes are mounted on three fixed points of a handheld bracket, forming an isosceles triangle with the geometric lines connecting the three fixed points. The side lengths of the three sides of the isosceles triangle are recorded as the fixed geometric baseline parameters. The synchronous triggering circuit of the three probes is activated, and the distance acquisition function of the three probes is activated simultaneously on the rising edge of the same clock pulse. Each probe transmits a measurement signal and receives the echo signal reflected from the measured plane. Based on the time difference between the transmission time of the measurement signal and the reception time of the echo signal, the vertical distance from each of the three probes to the measured plane is calculated. These three vertical distances are arranged in the order of the probe numbers to form the three sets of real-time distance values.

[0021] In a specific implementation, the first, second, and third probes are respectively mounted on the first, second, and third fixed supports of the handheld bracket, so that the geometric lines connecting the first, second, and third fixed supports form an isosceles triangle. In the specific scenario of measuring a large flat surface, the lengths of the first, second, and third sides of the isosceles triangle are recorded as fixed geometric baseline parameters. In some embodiments, the lengths of the first and second sides in the fixed geometric baseline parameters are equal, and the length of the third side is used as the base side length of the isosceles triangle. Optionally, the fixed geometric baseline parameters are pre-calibrated using a laser interferometer and stored in the internal memory of the handheld bracket. It can be understood that the magnitude of the fixed geometric baseline parameters determines the initial plane reference for spatial coordinate transformation. In a specific implementation, the relative positions of the first, second, and third fixed supports on the surface of the handheld bracket remain rigidly fixed and immutable.

[0022] In specific implementation, the synchronous triggering circuit of the first, second, and third probes is activated, simultaneously activating their distance acquisition functions on the rising edge of the clock pulse signal. In the specific scenario of measuring a large flat surface, the first, second, and third probes simultaneously transmit measurement signals towards the large flat surface. In some embodiments, the measurement signal propagates in the transmission space and contacts the large flat surface, and the first, second, and third probes respectively receive the first echo signal, second echo signal, and third echo signal reflected back from the large flat surface. Optionally, the clock pulse signal of the synchronous triggering circuit is generated by the crystal oscillator of the main control chip inside the handheld holder. It can be understood that the rising edge of the clock pulse signal enables the first, second, and third probes to achieve complete synchronization in the time dimension.

[0023] In practical implementation, based on the time difference between the transmission time of the measurement signal and the reception times of the first, second, and third echo signals, the vertical distances from the first, second, and third probes to the surface of the large flat plate are calculated respectively; the formula for calculating the vertical distance is: in: Indicates vertical distance. This indicates the speed at which a measured signal propagates in a medium. This represents the time difference. The calculated first, second, and third vertical distances are arranged in the order of the probe numbers to form three sets of real-time distance values. In practice, the first vertical distance corresponds to the first probe, the second vertical distance corresponds to the second probe, and the third vertical distance corresponds to the third probe, ultimately combining to form a data vector containing data in three independent dimensions.

[0024] In one embodiment of the present invention, a support coordinate system is established with the geometric center of the three fixed fulcrums on the handheld bracket as the origin and the front direction of the handheld bracket as the normal direction. The installation position coordinates of the three probes are marked in the support coordinate system, and each installation position coordinate is calculated from fixed geometric baseline parameters. The three sets of real-time distance values ​​are assigned to the corresponding installation position coordinates of the three probes, causing each probe's installation position coordinate to move along the normal direction of the support coordinate system by a distance equal to the probe's real-time distance value, resulting in three spatial point coordinates located on the measured plane. Based on the three spatial point coordinates, a unique spatial plane equation passing through these three spatial point coordinates is solved. From the spatial plane equation, the pitch angle of the measured plane relative to the support coordinate system about the horizontal axis and the roll angle about the vertical axis are extracted. The pitch angle is then... The pitch angle and roll angle are combined to form the instantaneous attitude angle. The coordinates of three spatial points are represented as the first spatial point coordinates, the second spatial point coordinates, and the third spatial point coordinates, respectively. The first direction vector is obtained by subtracting the second spatial point coordinates from the first spatial point coordinates, and the second direction vector is obtained by subtracting the third spatial point coordinates from the first spatial point coordinates. The cross product of the first and second direction vectors is calculated to obtain the normal vector of the measured plane. The normal vector is normalized by dividing it by its own magnitude to obtain the unit normal vector. The original normal vector of the support coordinate system is denoted as the unit vector pointing in the positive direction. The angle between the unit normal vector and the original normal vector is calculated. The angle is decomposed into the horizontal and vertical axes of the support coordinate system to obtain the pitch angle and the roll angle. The pitch angle and roll angle are combined to form the instantaneous attitude angle.

[0025] In the specific implementation, a support coordinate system is established with the geometric center of the three fixed support points on the handheld bracket as the origin and the front direction of the handheld bracket as the normal direction. In the specific scenario of measuring the guide plane of an industrial machine tool, the installation position coordinates of the first probe, the second probe, and the third probe are marked in the support coordinate system. Each installation position coordinate is calculated from the fixed geometric baseline parameters. In the specific implementation, the first, second, and third real-time distance values ​​from the three sets of real-time distance values ​​are assigned to the corresponding installation position coordinates of the first, second, and third probes, respectively. This causes the installation position coordinates of the first, second, and third probes to move along the normal direction of the support coordinate system by a distance equal to the first, second, and third real-time distance values, respectively, to obtain the first, second, and third spatial point coordinates, which are located on the guide plane of the industrial machine tool. In some embodiments, the support coordinate system has the horizontal axis as the x-axis, the vertical axis as the y-axis, and the direction perpendicular to the front of the handheld support as the normal axis. Optionally, fixed geometric baseline parameters are pre-stored in the microprocessor register and converted into numerical values ​​of the installation position coordinates in real time. It can be understood that the determination of the first spatial point coordinates, the second spatial point coordinates, and the third spatial point coordinates introduces the geometric state of the industrial machine tool guide plane into the support coordinate system.

[0026] In practical implementation, based on the coordinates of the first, second, and third spatial points, a unique spatial plane equation is solved using these coordinates. From this equation, the pitch angle (representing rotation about the horizontal axis) and roll angle (representing rotation about the vertical axis) of the industrial machine tool guideway plane relative to the support coordinate system are extracted. These pitch and roll angles are then combined to form the instantaneous attitude angle. The first direction vector is obtained by subtracting the second spatial point coordinates from the first spatial point coordinates, and the second direction vector is obtained by subtracting the third spatial point coordinates from the first spatial point coordinates. The cross product of the first and second direction vectors is calculated to obtain the normal vector of the industrial machine tool guideway plane. The formula for calculating the cross product is as follows: in: This represents the normal vector of the guide plane of an industrial machine tool. Represents the first direction vector. This represents the second direction vector. This represents the cross product symbol. In some embodiments, the normal vector is normalized by dividing it by its own magnitude to obtain the unit normal vector. Optionally, the cross product operation between the first and second direction vectors is performed using matrix multiplication with algebraic cofactors. It can be understood that the unit normal vector uniquely determines the orientation of the industrial machine tool guide plane in space.

[0027] In practical implementation, the original normal vector of the support coordinate system is denoted as a unit vector pointing in the positive direction. The angle between the unit normal vector and the original normal vector is calculated, and the angle is decomposed into the horizontal and vertical axes of the support coordinate system to obtain the pitch angle and roll angle. The pitch angle and roll angle are combined into the instantaneous attitude angle. In the specific scenario of measuring the guide plane of an industrial machine tool, the instantaneous attitude angle reflects the tilt state of the handheld support relative to the guide plane of the industrial machine tool at the current sampling moment.

[0028] In one embodiment of the present invention, a six-axis inertial measurement unit is installed inside the handheld support. The six-axis inertial measurement unit outputs in real time the linear acceleration along the three orthogonal axes and the angular velocity of the handheld support rotating around the three orthogonal axes. The linear acceleration and angular velocity are combined to form the three-axis inertial motion data. A global timestamp is assigned to the three sets of real-time distance values ​​sampled each time, and an inertial timestamp is assigned to each output three-axis inertial motion data. Three-axis inertial motion data whose difference between the inertial timestamp and the global timestamp is less than a preset threshold are selected from all three-axis inertial motion data. The selected three-axis inertial motion data is bound to the instantaneous attitude angle corresponding to the same global timestamp to form a fusion record. All fusion records are arranged in the order of the global timestamps to generate the fused attitude sequence.

[0029] In a specific implementation, a six-axis inertial measurement unit (IMU) is installed inside the handheld support. In the scenario of measuring the plane of a ship's deck, the IMU outputs in real-time the linear acceleration along the three orthogonal axes and the angular velocity of rotation around those axes. The linear acceleration and angular velocity are then combined to form three-axis inertial motion data. In this implementation, the central processing unit inside the handheld support assigns a global timestamp to each set of three real-time distance values ​​sampled, and also assigns an inertial timestamp to each output three-axis inertial motion data. In some embodiments, the global timestamp is uniformly distributed by a high-precision system clock inside the handheld support. Optionally, an independent hardware timer is deployed within the six-axis IMU to generate the inertial timestamp. It is understood that the global timestamp and the inertial timestamp have independent timelines, requiring a timestamp alignment algorithm to establish a correspondence.

[0030] In practical implementation, three-axis inertial motion data with a difference between the inertial timestamp and the global timestamp less than a preset threshold are selected from all three-axis inertial motion data. In the specific scenario of measuring the ship's deck plane, the formula for calculating the timestamp difference is: in: Indicates the timestamp difference. Represents inertial timestamps, This represents the global timestamp. In specific implementations, the selected three-axis inertial motion data are bound to the instantaneous attitude angle corresponding to the same global timestamp as a fusion record. In some embodiments, all fusion records are arranged in chronological order according to their global timestamps to generate a fused attitude sequence. Optionally, three-axis inertial motion data with a timestamp difference greater than a preset threshold are automatically discarded. It can be understood that the fused attitude sequence is composed of multiple fusion records arranged consecutively in chronological order.

[0031] In one embodiment of the present invention, see [reference] Figure 3 The three-axis inertial motion data corresponding to the current sampling moment is extracted from the fused attitude sequence. A second time integration operation is performed on the linear acceleration in the three-axis inertial motion data to obtain the three-dimensional displacement vector of the handheld support within the sampling time interval. A first time integration operation is performed on the angular velocity in the three-axis inertial motion data to obtain the three-dimensional rotation vector of the handheld support within the sampling time interval. The three-dimensional rotation vector is superimposed with the instantaneous attitude angle at the current sampling moment to obtain the actual spatial attitude of the handheld support. Based on the three-dimensional displacement vector and the actual spatial attitude, the reference position offset of the handheld support relative to the previous sampling moment is calculated. The projected components of the reference position offset in the three probe directions are subtracted from the three sets of real-time distance values ​​to obtain the corrected distance value. The three-dimensional displacement vector is decomposed... Displacement components along the horizontal axis, the vertical axis, and the normal axis are obtained along the three orthogonal axes of the handheld support. Based on the pitch and roll components in the actual spatial attitude, a rotation matrix is ​​constructed. The displacement components along the horizontal axis and the vertical axis are projected onto the tangent direction of the measured plane through the rotation matrix to obtain the lateral projection component and the longitudinal projection component. The displacement component along the normal axis is directly used as the normal projection component. The lateral projection component, the longitudinal projection component, and the normal projection component are combined into the reference position offset. The corresponding component of the reference position offset is subtracted from the three sets of real-time distance values ​​to output the corrected distance value. The rotation matrix is ​​constructed in Euler angle form with a rotation order prioritizing the horizontal axis.

[0032] In specific implementation, the three-axis inertial motion data corresponding to the current sampling moment is extracted from the fused attitude sequence. In the specific scenario of measuring the plane of an aircraft wing panel, a second time integration operation is performed on the linear acceleration in the three-axis inertial motion data to obtain the three-dimensional displacement vector of the handheld support within the sampling time interval; a first time integration operation is performed on the angular velocity in the three-axis inertial motion data to obtain the three-dimensional rotation vector of the handheld support within the sampling time interval. The three-dimensional rotation vector is superimposed with the instantaneous attitude angle at the current sampling moment to obtain the actual spatial attitude of the handheld support. In some embodiments, the second time integration operation is performed on the discrete time sequence using a numerical integrator. Optionally, the sampling time interval is determined by the interrupt period of a hardware timer. It can be understood that the actual spatial attitude accurately describes the three-dimensional rotational state of the handheld support as it moves on the plane of the aircraft wing panel.

[0033] In practical implementation, based on the three-dimensional displacement vector and the actual spatial attitude, the offset of the handheld support relative to the reference position at the previous sampling moment is calculated. The projected components of the reference position offset in the three probe directions are subtracted from the three sets of real-time distance values ​​to obtain the corrected distance value. The three-dimensional displacement vector is decomposed into the three orthogonal axes of the handheld support, yielding displacement components along the transverse axis, the longitudinal axis, and the normal axis. In some embodiments, based on the pitch and roll components in the actual spatial attitude, a rotation matrix is ​​constructed. The displacement components along the transverse and longitudinal axes are projected onto the tangent direction of the aircraft wing panel plane through the rotation matrix, yielding the lateral and longitudinal projection components. The formula for calculating the lateral projection component is: in: Indicates the lateral projection component. Represents the rotation matrix. This represents the displacement component along the horizontal axis. Optionally, the rotation matrix is ​​constructed using Euler angles, following a horizontal-axis-first rotation order. It can be understood that establishing the rotation matrix transforms the displacement in the handheld support coordinate system to the tangential geometric coordinate space of the aircraft wing panel plane. In specific implementation, the displacement component along the normal direction is directly used as the normal projection component. The horizontal projection component, longitudinal projection component, and normal projection component are combined into a reference position offset. The corresponding component of the reference position offset is subtracted from each of the three sets of real-time distance values ​​to output the corrected distance value for the aircraft wing panel plane.

[0034] In one embodiment of the present invention, a continuous sliding time window is set, the length of which includes a fixed number of sampling periods. At the end of each sampling period, the three sets of corrected distance values ​​calculated within that sampling period are stored in the buffer corresponding to the sliding time window. When the sliding time window is filled, the arithmetic mean of each set of corrected distance values ​​in the buffer is calculated, and the average corrected distance value set is obtained by fine-tuning. Then, the standard deviation of each set of corrected distance values ​​in the buffer is calculated to obtain the set of corrected distance value dispersion. The average corrected distance value set is used as the distance reference value of the measured plane, and the maximum value in the set of corrected distance value dispersion is used as the flatness error value of the measured plane. The distance reference value and the flatness error value are combined and output as the final flatness parameter. The flatness error value is obtained by multiplying the maximum value in the set of corrected distance value dispersion by a preset scaling factor and adding a preset zero-point offset.

[0035] In a specific implementation, a continuous sliding time window is set. In the specific scenario of measuring the plane of a marble inspection platform, the length of the continuous sliding time window includes a fixed number of sampling periods. At the end of each sampling period, the three sets of corrected distance values ​​calculated in the current sampling period are stored in the buffer corresponding to the continuous sliding time window. In a specific implementation, when the continuous sliding time window is filled, the arithmetic mean of each set of corrected distance values ​​in the buffer is calculated to obtain the average corrected distance value set. Then, the standard deviation of each set of corrected distance values ​​in the buffer is calculated to obtain the set of corrected distance value dispersion. In some embodiments, the fixed number of sampling periods included in the continuous sliding time window is determined by the measurement accuracy requirements of the marble inspection platform plane. Optionally, the buffer is allocated by a dual-port static random access memory inside the handheld bracket. It can be understood that dynamically refreshing the corrected distance values ​​through a continuous sliding time window can filter out random noise generated by high-frequency disturbances.

[0036] In practical implementation, the average corrected distance value set is used as the distance reference value for the marble inspection platform plane, and the maximum value in the set of corrected distance value dispersion is used as the original basis for calculating the flatness error value of the marble inspection platform plane. The distance reference value and the flatness error value are combined and output as the final flatness parameter of the marble inspection platform plane. In practical implementation, the formula for calculating the flatness error value is: in: Indicates the flatness error value. This represents the maximum value in the set of distance value dispersions. This represents the preset scaling factor. This represents a preset zero-point offset. In some embodiments, the flatness error value is obtained by linearly scaling and biasing the maximum value in the set of dispersion values ​​of the correction distance using a preset scaling factor and a preset zero-point offset. Optionally, the preset scaling factor and preset zero-point offset are determined at the factory using a standard flatbed calibrator and stored in non-volatile memory. It is understood that correction using the preset scaling factor and preset zero-point offset can eliminate measurement system errors caused by the structural manufacturing tolerances of the handheld bracket itself and by environmental temperature drift.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A handheld three-probe planar parameter measurement method, characterized in that, The method includes; Three probes are arranged and mounted on a handheld bracket according to a fixed geometric baseline. The vertical distance data between the three probes and the plane being measured is collected simultaneously to obtain three sets of real-time distance values. Based on the three sets of real-time distance values ​​and the fixed geometric baseline parameters of the three probes on the handheld bracket, a spatial plane equation with the three probes as reference points is constructed, and the instantaneous attitude angle of the measured plane relative to the handheld bracket is calculated. The three-axis inertial motion data of the handheld support during the measurement process are collected. The three-axis inertial motion data includes linear acceleration and angular velocity. After preprocessing the linear acceleration and angular velocity with different integration orders, the three-axis inertial motion data is timestamped with the instantaneous attitude angle to generate a fused attitude sequence. Based on the fused attitude sequence, the spatial displacement error of the handheld support at the sampling time is compensated in reverse to obtain the corrected distance value between the probe and the measured plane. The final flatness parameters of the measured plane are output by statistically averaging multiple corrected distance values ​​obtained within a continuous sampling period.

2. The handheld three-probe planar parameter measurement method according to claim 1, characterized in that, The steps of arranging three probes on a handheld stand according to a fixed geometric baseline, synchronously collecting vertical distance data between the three probes and the plane being measured, and obtaining three sets of real-time distance values ​​include: The three probes are respectively installed on the three fixed support points of the handheld bracket, so that the geometric lines connecting the three fixed support points form an isosceles triangle, and the side lengths of the three sides of the isosceles triangle are recorded as the fixed geometric baseline parameters. The synchronous triggering circuit of the three probes is activated, and the distance acquisition function of the three probes is activated simultaneously on the rising edge of the same clock pulse. Each probe transmits a measurement signal and receives the echo signal reflected back from the measured plane. Based on the time difference between the transmission time of the measurement signal and the reception time of the echo signal, the vertical distance from each of the three probes to the measured plane is calculated, and these three vertical distances are arranged in the order of the probe numbers to form the three sets of real-time distance values.

3. The handheld three-probe planar parameter measurement method according to claim 2, characterized in that, Based on the three sets of real-time distance values ​​and the fixed geometric baseline parameters of the three probes on the handheld bracket, the steps of constructing a spatial plane equation with the three probes as reference points and calculating the instantaneous attitude angle of the measured plane relative to the handheld bracket are specifically included. A support coordinate system is established with the geometric center of the three fixed support points on the handheld bracket as the origin and the front direction of the handheld bracket as the normal direction. The installation position coordinates of the three probes are marked in the support coordinate system. The coordinates of each installation position are calculated from the fixed geometric baseline parameters. The three sets of real-time distance values ​​are respectively assigned to the installation position coordinates of the three corresponding probes, so that the installation position coordinates of each probe are moved along the normal direction of the bracket coordinate system by a distance equal to the real-time distance value of the probe, thereby obtaining the coordinates of three spatial points, which are located on the plane being measured. Based on the coordinates of the three spatial points, solve the unique spatial plane equation passing through these three spatial point coordinates. Extract the pitch angle and roll angle of the measured plane relative to the support coordinate system about the horizontal axis from the spatial plane equation. Combine the pitch angle and roll angle to form the instantaneous attitude angle.

4. The handheld three-probe planar parameter measurement method according to claim 3, characterized in that, Based on the coordinates of the three spatial points, the steps of solving the unique spatial plane equation passing through the coordinates of these three spatial points, extracting the pitch angle and roll angle of the measured plane relative to the support coordinate system about the horizontal axis from the spatial plane equation, and combining the pitch angle and roll angle into the instantaneous attitude angle, specifically include: The coordinates of the three spatial points are represented as the first spatial point coordinates, the second spatial point coordinates, and the third spatial point coordinates, respectively. The first direction vector is obtained by subtracting the second spatial point coordinates from the first spatial point coordinates, and the second direction vector is obtained by subtracting the third spatial point coordinates from the first spatial point coordinates. Calculate the cross product of the first direction vector and the second direction vector to obtain the normal vector of the measured plane. Divide the normal vector by its own magnitude to normalize it and obtain the unit normal vector. The original normal vector of the support coordinate system is denoted as a unit vector pointing in the positive direction. The angle between the unit normal vector and the original normal vector is calculated. The angle is decomposed into the horizontal and vertical axes of the support coordinate system to obtain the pitch angle and the roll angle. The pitch angle and the roll angle are combined to form the instantaneous attitude angle.

5. The handheld three-probe planar parameter measurement method according to claim 1, characterized in that, The steps of collecting three-axis inertial motion data of the handheld support during the measurement process, aligning the three-axis inertial motion data with the instantaneous attitude angles with timestamps, and generating a fused attitude sequence specifically include: A six-axis inertial measurement unit is installed inside the handheld bracket. The six-axis inertial measurement unit outputs the linear acceleration of the handheld bracket along the three orthogonal axes and the angular velocity of the rotation around the three orthogonal axes in real time. The linear acceleration and angular velocity are combined into the three-axis inertial motion data. A global timestamp is assigned to the three sets of real-time distance values ​​for each sampling, and an inertial timestamp is assigned to each output three-axis inertial motion data. The absolute difference between the inertial timestamp and the global timestamp is calculated, and a dynamic threshold for the absolute difference is set. The dynamic threshold is proportional to the rate of change of the instantaneous angular velocity of the handheld support between adjacent sampling times. Three-axis inertial motion data with a difference between the inertial timestamp and the global timestamp less than the preset threshold are selected from all three-axis inertial motion data. The selected three-axis inertial motion data are bound to the instantaneous attitude angle corresponding to the same global timestamp as a fusion record. All fusion records are arranged in chronological order of global timestamps to generate the fusion attitude sequence.

6. The handheld three-probe planar parameter measurement method according to claim 1, characterized in that, The step of reversely compensating for the spatial displacement error of the handheld support at the sampling time based on the fused attitude sequence to obtain the corrected distance value between the probe and the measured plane specifically includes: Extract the three-axis inertial motion data corresponding to the current sampling time from the fused attitude sequence, and perform a second time integration operation on the linear acceleration in the three-axis inertial motion data to obtain the three-dimensional displacement vector of the handheld support within the sampling time interval; Perform a time integration operation on the angular velocity in the three-axis inertial motion data to obtain the three-dimensional rotation vector of the handheld support within the sampling time interval. Superimpose the three-dimensional rotation vector with the instantaneous attitude angle at the current sampling moment to obtain the actual spatial attitude of the handheld support. Based on the three-dimensional displacement vector and the actual spatial posture, the offset of the handheld support relative to the reference position at the previous sampling time is calculated. The corrected distance value is obtained by subtracting the projection components of the reference position offset in the three probe directions from the three sets of real-time distance values.

7. The handheld three-probe planar parameter measurement method according to claim 6, characterized in that, The steps of calculating the reference position offset of the handheld bracket relative to the previous sampling time based on the three-dimensional displacement vector and the actual spatial posture, and subtracting the projection components of the reference position offset in the three probe directions from the three sets of real-time distance values ​​to obtain the corrected distance value, specifically include: The three-dimensional displacement vector is decomposed into three orthogonal axes of the handheld bracket to obtain the displacement components along the horizontal axis, the displacement components along the vertical axis, and the displacement components along the normal direction. Based on the pitch and roll components in the actual spatial attitude, a rotation matrix is ​​constructed, and the displacement components along the horizontal axis and the displacement components along the vertical axis are projected onto the tangent direction of the measured plane through the rotation matrix to obtain the horizontal projection component and the vertical projection component. Based on the probe position corresponding to the minimum value among the three sets of real-time distance values, a weighting coefficient is dynamically determined. The displacement component along the normal direction is directly used as the normal projection component. After multiplying the normal projection component by the weighting coefficient, it is combined with the lateral projection component, longitudinal projection component, and normal projection component to form the reference position offset. The corresponding component of the reference position offset is subtracted from the three sets of real-time distance values ​​respectively, and the corrected distance value is output.

8. The handheld three-probe planar parameter measurement method according to claim 7, characterized in that, The rotation matrix is ​​constructed in Euler angle form according to the rotation order prioritizing the horizontal axis.

9. The handheld three-probe planar parameter measurement method according to claim 1, characterized in that, The steps of statistically averaging multiple corrected distance values ​​obtained within a continuous sampling period to output the final flatness parameters of the measured plane include: A continuous sliding time window is set, the length of which includes a fixed number of sampling periods. The length of the sliding time window is inversely proportional to the real-time movement speed of the handheld support. At the end of each sampling period, the three sets of corrected distance values ​​calculated within that sampling period are stored in the buffer corresponding to the sliding time window. Once the sliding time window is filled, the arithmetic mean is calculated for each set of corrected distance values ​​in the buffer to obtain the set of average corrected distance values. Then, the standard deviation is calculated for each set of corrected distance values ​​in the buffer to obtain the set of corrected distance value dispersion. The average corrected distance value set is used as the distance reference value of the measured plane, and the maximum value in the set of corrected distance value dispersion is used as the flatness error value of the measured plane. The distance reference value and the flatness error value are combined and output as the final flatness parameter.

10. A handheld three-probe planar parameter measurement method according to claim 9, characterized in that, The flatness error value is obtained by multiplying the maximum value in the set of dispersion values ​​of the corrected distance value by a preset scaling factor and adding a preset zero offset.

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