A method and apparatus for compensating for the accuracy of pressure and pressure center measurement based on a weighing sensor.

Abstract

This invention discloses a compensation method and device for pressure and pressure center measurement accuracy based on a weighing sensor, belonging to the field of biomechanical measurement and signal processing technology. The method includes: acquiring pressure measurement values, pressure center measurement coordinates, and corresponding true pressure values ​​and pressure center coordinates at multiple preset calibration points; based on the measured and true values ​​at the geometric center calibration point, correcting the pressure measurement values ​​and pressure center measurement coordinates at other calibration points to determine the pressure correction measurement error and pressure center correction measurement error at each calibration point; establishing a target error model; and acquiring the pressure measurement value and pressure center measurement coordinates at any test point, calculating the compensation error corresponding to the test point based on the target error model, and compensating for the measured value at the test point. This invention solves the problem of uneven spatial distribution of measurement errors caused by the structural characteristics of weighing sensors.

Description

Technical Field

[0001] This application relates to the field of biomechanical measurement and signal processing technology, and in particular to a method and apparatus for compensating the accuracy of pressure and pressure center measurement based on a weighing sensor. Background Technology

[0002] In applications such as human balance testing, gait analysis, and rehabilitation training assessment, accurate measurement of the pressure exerted by the human body on a support surface and the location of its center of pressure (COP) is crucial. Measurement devices based on pressure sensor arrays, such as pressure pads or force tables, can provide high-resolution pressure distribution data, but their high cost limits their widespread application in consumer-grade and general-purpose rehabilitation equipment.

[0003] As an alternative, the use of multiple (usually three or four) discrete load cells (or force sensors) to construct a measurement system has been widely studied due to its significant cost advantage. However, such systems have an inherent technical contradiction: the load cells themselves are designed to accurately measure vertical loads, but their mechanical structure and strain gauge layout will produce position-dependent measurement errors when subjected to non-central loads or horizontal components. This error is not uniformly distributed in space, resulting in differences in the system's output value when the same pressure is applied at different locations on the support surface, which in turn seriously affects the accuracy of the pressure center coordinate calculation. Existing technologies typically employ simple linear calibration or zero-point calibration, but this cannot solve the fundamental problem of the spatial non-uniformity of the error field, making it difficult to meet the high accuracy requirements of clinical or research applications. Therefore, how to systematically identify and compensate for this position-dependent nonlinear error field while maintaining the advantage of low-cost hardware has become a pressing technical challenge in this field. Summary of the Invention

[0004] In the first aspect, this application provides a compensation method for the measurement accuracy of pressure and pressure center based on a weighing sensor, which aims to solve the problem of insufficient measurement accuracy caused by uneven spatial distribution of errors in the existing weighing sensor-based measurement system.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] A compensation method for pressure and pressure center measurement accuracy based on a weighing sensor, the method comprising: acquiring calibration data of a measurement system at multiple preset calibration points, the measurement system comprising at least three weighing sensors, the calibration data including pressure measurement values, pressure center measurement coordinates, and corresponding true pressure values ​​and pressure center true coordinates at a geometric center calibration point and each of the remaining preset calibration points; determining the measurement error at the geometric center calibration point and the pressure correction measurement errors and pressure center correction measurement errors at the remaining preset calibration points based on the measured values ​​and true values ​​at the geometric center calibration point and the remaining preset calibration points; determining the radial distance and polar angle values ​​at each preset calibration point based on the Cartesian coordinates of the remaining preset calibration points in the coordinate system of the measurement system; and establishing a target error model, the target error model comprising at least a characterization of... The system establishes a first piecewise linear mapping relationship between the pressure correction measurement error and the polar angle value, a second piecewise linear mapping relationship between the pressure center correction measurement error and the polar angle value, and a third piecewise linear mapping relationship between the radial distance value and the polar angle value. It acquires real-time measurement data of the measurement system for the test point, including the measured pressure value and the measured coordinates of the pressure center. Based on the target error model, it calculates the pressure compensation error, the pressure center compensation error, and the corresponding radial reference distance value for the test point. Based on the measurement error of the geometric center calibration point, the pressure compensation error, the pressure center compensation error, and the radial reference distance value, it compensates for the measured pressure value and the measured coordinates of the pressure center to obtain the compensated pressure value and the compensated pressure center coordinates.

[0007] Optionally, based on the measured values ​​and true values ​​at the geometric center calibration point and the remaining preset calibration points, the measurement error at the geometric center calibration point and the pressure correction measurement error and pressure center correction measurement error at the remaining preset calibration points are determined, including: for the i-th preset calibration point, its pressure correction measurement error Determined in the following manner: ,in, The pressure measurement value at the i-th preset calibration point. The true pressure value at the i-th preset calibration point. The pressure measurement value at the geometric center calibration point. The true pressure value at the geometric center calibration point; for the i-th preset calibration point, the pressure center correction measurement error. Determined in the following manner: ,in, The pressure center measurement coordinates of the i-th preset calibration point are given. Let i be the true coordinates of the pressure center at the i-th preset calibration point. The true coordinates of the pressure center of the geometric center calibration point are given.

[0008] Optionally, the step of calculating the pressure compensation error, pressure center compensation error, and corresponding radial reference distance value corresponding to the point to be measured includes: calculating the polar angle value to be measured corresponding to the pressure center measurement coordinates of the point to be measured; determining the pressure compensation error based on the polar angle value to be measured in the first piecewise linear mapping relationship; determining the pressure center compensation error based on the polar angle value to be measured in the second piecewise linear mapping relationship; and determining the radial reference distance value based on the polar angle value to be measured in the third piecewise linear mapping relationship.

[0009] Optionally, the step of compensating the measured pressure value and the measured coordinates of the center of the pressure to be measured includes: calculating the compensated pressure value based on the measured pressure value, the measured pressure value and the true value of the geometric center calibration point, the pressure compensation error, the radial reference distance value, and the radial distance value determined according to the modulus of the measured coordinates of the center of the pressure to be measured; and calculating the compensated pressure center coordinates based on the measured coordinates of the center of the pressure to be measured, the measured pressure center value and the true value of the geometric center calibration point, the pressure center compensation error, the radial reference distance value, and the radial distance value determined according to the modulus of the measured coordinates of the center of the pressure to be measured.

[0010] Optionally, the compensated pressure value Determined in the following manner: ,in, The measured value of the pressure to be measured. This is the pressure compensation error. The radial reference distance value, The radial distance value to be measured is determined based on the modulus of the coordinates of the center of the pressure to be measured.

[0011] Optionally, the compensated pressure center coordinates Determined in the following manner: ,in, The coordinates of the center of the pressure to be measured are given. To compensate for the pressure center error, The radial reference distance value, The radial distance value to be measured is determined based on the modulus of the coordinates of the center of the pressure to be measured.

[0012] Optionally, the plurality of preset calibration points include a central calibration point located at the origin of the coordinate system of the measurement system, and a plurality of non-central calibration points symmetrically distributed along at least two mutually orthogonal coordinate axes.

[0013] Optionally, the origin of the coordinate system of the measurement system is the geometric centroid of the at least three weighing sensors.

[0014] Secondly, this application provides a compensation device based on the pressure and pressure center measurement accuracy of a weighing sensor.

[0015] To achieve the above objectives, this application adopts the following technical solution:

[0016] A compensation device for pressure and pressure center measurement accuracy based on weighing sensors, the device comprising: at least three weighing sensors for forming a measurement system; a memory for storing program instructions; and a processor for executing the program instructions to implement the method as described in any of the preceding claims.

[0017] Thirdly, this application provides a computer-readable storage medium.

[0018] To achieve the above objectives, this application adopts the following technical solution:

[0019] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described in any of the preceding claims.

[0020] This application constructs a piecewise linear mapping model that correlates measurement error with the polar coordinate angle of the loading position to accurately characterize and quantify the inherent, spatially non-uniform error field of the measurement system. Instead of simply correcting the measurement results globally, this method establishes an independent error mapping function for each angular direction in space. This allows for the precise and dynamic calculation of the systematic error at any measured point's real-time location, followed by targeted compensation. This approach effectively combines the cost advantage of low-cost weighing sensors with the requirement for high-precision measurement. Through the construction of software algorithms, it significantly improves the performance ceiling of the hardware system, achieving the beneficial effect of using economical hardware to realize high-precision pressure and pressure center measurement. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the physical layout of a sensor provided in an embodiment of this application.

[0023] Figure 2This is a schematic diagram of the calibration point distribution provided in one embodiment of this application.

[0024] Figure 3 This is a schematic diagram of a method flow provided in an embodiment of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0029] This embodiment provides a compensation method for the measurement accuracy of pressure and pressure center based on a weighing sensor. In a specific implementation, this method selects multiple discrete calibration points within the support surface of the measurement system, accurately measures and calculates the pressure and pressure center errors at each point, and then correlates these error quantities with the spatial position (specifically, angles in polar coordinates) of the calibration points to construct a piecewise linear error field mapping model. This allows for the calculation of the corresponding system error for any newly measured point within the measurement range through position angle interpolation, and precise compensation for the original measurement value. This method solves the technical problem commonly found in existing measurement systems using multiple weighing sensors: the measurement errors caused by the sensor's structural characteristics and physical layout are spatially unevenly distributed and difficult to eliminate through simple linear calibration. It achieves the beneficial effect of significantly improving the measurement accuracy of pressure and pressure center without increasing hardware costs.

[0030] Reference Figure 3 This application provides a compensation method based on the pressure and pressure center measurement accuracy of a weighing sensor. This method can be applied to applications such as... Figure 1 As shown, it consists of four weighing sensors. , , and A measuring device is constructed. In an exemplary physical structure, the four load cells are located at the four vertices A, B, C, and D of a rectangular support surface. The length of the rectangular support surface can be defined as... The width can be defined as To facilitate subsequent calculations and analysis, a two-dimensional Cartesian coordinate system O-XY is established. The origin O of this coordinate system is located at the geometric centroid of the four weighing sensors, and the X-axis is parallel to the axis formed by the sensors. and The line formed by the sensor has its Y-axis parallel to the line drawn by the sensor. and The lines that form the coordinate system. Under this coordinate system definition, the center coordinates of the four weighing sensors can be expressed as follows: , , and When external pressure is applied to the support surface, each sensor outputs an electrical signal proportional to the load it bears. By collecting and processing the signals from these four sensors, the magnitude of the total pressure and the coordinates of the pressure center can be obtained. The method may include the following steps:

[0031] S100: Acquire calibration data of a measurement system at multiple preset calibration points. The measurement system consists of at least three weighing sensors. The calibration data includes the pressure measurement value, pressure center measurement coordinates, and corresponding true pressure value and pressure center true value coordinates at the geometric center calibration point and each of the other preset calibration points.

[0032] The core task in this step is to comprehensively investigate or map the error characteristics of the measurement system. To achieve this, a set of representative discrete points needs to be strategically selected as calibration points within the system's effective measurement area. The selection of these calibration points is crucial to the accuracy of the subsequent error model.

[0033] Reference Figure 2 In a preferred embodiment, nine preset calibration points were selected, denoted as follows: The distribution of these points was carefully designed to cover key locations within the measurement area. Specifically, calibration points... It coincides with the origin O of the coordinate system and serves as the reference point or benchmark for the entire calibration process. The remaining eight points... to Around the center point They are geometrically symmetrically distributed. For example, calibration points. and It can be located on the Y-axis, symmetrical about the origin; calibration point and It can be located on the X-axis, symmetrical about the origin; while the calibration point , , , The errors are distributed across the four quadrants and are symmetrical with each other, for example, about the X-axis, Y-axis, or the origin. This symmetrical layout helps to comprehensively capture the error variation patterns of the system in different directions and at different distances, and can also, to some extent, test whether the system error also has a certain symmetry.

[0034] For each selected calibration point Precise loading operations are required. This typically necessitates the use of high-precision loading equipment (e.g., a weight loader with positioning devices or a robotic arm). At the calibration point... At a given location, a standard weight of known weight with a very small effective area is applied. This known weight is the true pressure value at that point, denoted as . Because the loading position is precisely preset, this calibration point... coordinates That is, the true coordinates of the pressure center, denoted as After applying a standard load, the measuring system will provide a set of readings, including the total pressure calculated by the system, i.e., the pressure measurement value, denoted as... and the pressure center coordinates calculated by the system. That is, the coordinates of the pressure center measurement, denoted as By repeating this process at all nine calibration points, a complete calibration dataset is obtained. This dataset contains the correspondence between the system's inputs (true values) and outputs (measured values) at nine discrete spatial locations, forming the data foundation for all subsequent error analyses and model building.

[0035] For example, suppose a measurement system is constructed from four load cells, the effective measurement area of ​​its support surface being comprised of... millimeters (mm) Millimeter (mm) definition. Nine calibration points were selected for calibration. During the calibration process, a standard weight with a mass of 10.00 kg was used, and the acceleration due to gravity was taken as 9.8 m / s². 2 Therefore, the true value of pressure The constant is 98.00 Newtons (N). True coordinates of the nine calibration points. And the pressure measurement values ​​obtained through the system. and pressure center measurement coordinates The measurements are recorded. Due to spatial non-uniform errors in the system, the measured values ​​will deviate from the true values, and the degree of deviation is location-dependent. A possible calibration dataset containing typical error characteristics is shown in the table below:

[0036]

[0037] Table 1: Exemplary calibration dataset for step S100

[0038] This dataset visually illustrates the problem this invention aims to solve: even when the true applied pressure is constant, pressure measurements fluctuate at different locations (ranging from 99.80 N to 102.25 N); simultaneously, the measured coordinates of the pressure center deviate significantly from the true coordinates, and the direction and magnitude of this deviation vector vary at different locations. For example, in At this point, the deviation in the Y coordinate reaches -4.5mm, while... The deviation of the X-coordinate at this point reached +3.8mm. This detailed calibration data, containing specific numerical values, is an indispensable prerequisite for building a high-precision error compensation model.

[0039] S200: Construct an error mapping model.

[0040] After obtaining the error data at the discrete calibration points, the next core task is to establish a continuous model that can describe the error distribution across the entire measurement plane. This invention proposes an innovative error mapping modeling method based on polar coordinates. This method does not directly fit the error values ​​to a two-dimensional surface; instead, it cleverly correlates them with the angles of the loading points, thus simplifying the complex two-dimensional problem into multiple one-dimensional piecewise linear interpolation problems. This step can be further decomposed into S210, S220, and S230.

[0041] S210: Based on the measured values ​​and true values ​​at the geometric center calibration point and the remaining preset calibration points, determine the measurement error at the geometric center calibration point and the pressure correction measurement error and pressure center correction measurement error at the remaining preset calibration points.

[0042] The purpose of this step is to transform the original measurement deviation values ​​into error parameters with clear physical meaning and a unified benchmark. Selecting the center point... It serves as a benchmark because it is typically the most stable or ideal measurement point in the system, and its deviation can be considered a systematic, position-independent benchmark offset. By subtracting this benchmark offset from the errors of other points, we obtain the relative error or spatial distortion error purely caused by positional changes, which is precisely the core object we wish to model and compensate for.

[0043] Regarding pressure measurement errors, this invention defines a pressure correction measurement error. The calculation formula is as follows: The construction of this formula is very ingenious. Among other things, Indicates in The ratio of the true value to the measured value at a point can be considered a local calibration coefficient. This is the calibration coefficient at the center reference point. Expression This represents the relative error of the center point itself. Therefore, the entire formula means that, from... Subtracting the reference relative error of the center point from the total relative error at the point, we can separate the error purely caused by position. Move to The resulting additional pressure error.

[0044] The definition of pressure center measurement error is more straightforward. It is defined as a pressure center correction measurement error vector. The calculation formula is: .here, yes The original deviation vector of the measured coordinates at a point relative to the true coordinates. These are the true coordinates of the center point. Note that in the original formula, the value of the center point was subtracted. This is in It is reasonable for the vector to be non-zero. However, in this embodiment, the true coordinates of the center point are... The origin (0,0) is usually the coordinate system, so this term can be ignored. However, to maintain rigor, this term is retained to handle more general cases, such as when there is a translation of the entire coordinate system.

[0045] therefore, It means The original position deviation vector at a point, corrected for center point deviation (if applicable), yields the net position deviation vector. The magnitude and direction of this vector directly reflect the degree of spatial distortion measured at that point. Through... Performing the above calculations on all eight non-center calibration points yields a set of key parameters describing the characteristics of the system error field in eight directions: eight pressure correction measurement error values ​​and eight pressure center correction measurement error vectors.

[0046] For example, the calibration data generated in the S100 example is used to perform error calculation.

[0047] First, calculate the center point. The reference parameters. The pressure measurement value at the center point. N, the true value of pressure N. The coordinates of the pressure center measurement at the center point are: mm, true coordinates are mm.

[0048] Based on these benchmark values, calculate the benchmark relative error of the center point: This value is a dimensionless ratio.

[0049] Now, calculate the pressure correction measurement error for the remaining eight calibration points in sequence. Correction of measurement error by pressure center .

[0050] For calibration points (i=1):

[0051] Pressure measurement value N, truth value N.

[0052] Pressure correction measurement error .

[0053] Pressure center measurement coordinates mm, truth coordinates mm.

[0054] Pressure center correction measurement error mm.

[0055] For calibration points (i=2):

[0056] Pressure measurement value N, truth value N.

[0057] Pressure correction measurement error .

[0058] Pressure center measurement coordinates mm, truth coordinates mm.

[0059] Pressure center correction measurement error mm.

[0060] In exactly the same way, to By calculating all the data, a complete table of error parameters can be obtained:

[0061]

[0062] Table 2: Calculation results of error parameters in step S210

[0063] This table, containing eight sets of error parameters, is the result of refining and correcting the original calibration data. It reveals the spatial distortion characteristics of the measurement field in a purer form, providing clean and standardized input for subsequent modeling.

[0064] S220: Based on the Cartesian coordinates of the remaining preset calibration points in the coordinate system of the measurement system, determine the radial distance and polar angle value at each preset calibration point.

[0065] In the Cartesian coordinate system, spatial position is determined by... Two variables describe the error if we want to establish it. The model requires handling a complex bivariate function. This invention introduces a polar coordinate system, changing the position description to radial distance. and polar angle value This transformation is one of the core steps of this method, motivated by the fact that the error distribution of many physical systems (including systems composed of symmetrically arranged sensors) exhibits simpler or more periodic variations in the angular direction than in the X and Y directions. By relating the error to the angle... By making connections, we can reduce the dimensionality of the problem.

[0066] For each off-center calibration point truth coordinates Its corresponding polar coordinates It can be calculated using the standard coordinate transformation formula.

[0067] Radial distance value It is a point The straight-line distance to the origin is calculated using the following formula: In this invention, this radial distance value It represents the distance dimension of the true location of the calibration point.

[0068] Polar angle value It is a point The angle between the line connecting the x-axis and the origin and the positive x-axis. Its calculation typically uses the arctangent function. To handle all four quadrants and avoid ambiguity, a two-parameter arctangent function is usually used. Its output range is or The calculation formula is: This angle value It is the core independent variable for establishing the linear mapping relationship, and it represents the directional dimension of the true value position of the calibration point.

[0069] By examining all eight off-center calibration points Performing this coordinate transformation will result in a coordinate transformation for each error data point. Each one is assigned a unique angular coordinate. and a radial distance coordinate .

[0070] For example, continue using the true coordinates of the calibration point in the S100 example. To perform polar coordinate transformation. The unit of angle will be degrees (°) for ease of understanding, where 0° corresponds to the positive X-axis direction, and a positive angle represents counterclockwise rotation.

[0071] For calibration points :

[0072] radial distance mm.

[0073] Polar angle

[0074] For calibration points :

[0075] radial distance mm.

[0076] Polar angle .

[0077] For calibration points :

[0078] radial distance mm.

[0079] Polar angle .

[0080] Similarly, calculations are performed for all eight points, and the results are integrated with the error data obtained from S210 to obtain the following comprehensive data table indexed by angle:

[0081]

[0082] Table 3: Comprehensive data table for step S220 (after polar coordinate transformation)

[0083] Note: To form a closed loop, The angle is considered to be 360°.

[0084] This table is the direct input for building a piecewise linear model. It clearly shows the three dependent variables (radial distance). Pressure correction measurement error Pressure center correction measurement error How does it change with the independent variable (polar angle)? It changes with the changes in ( ).

[0085] S230: Establish a target error model, wherein the target error model includes at least a first piecewise linear mapping relationship characterizing the pressure correction measurement error and the polar angle value, a second piecewise linear mapping relationship characterizing the pressure center correction measurement error and the polar angle value, and a third piecewise linear mapping relationship characterizing the radial distance value and the polar angle value.

[0086] It already has eight discrete angles The error value at any angle. A continuous model that can calculate the error can be used, employing a piecewise linear interpolation method. This means that, assuming that at any two adjacent calibration points (e.g., ... and The angle range between ) Within this range, the error changes linearly. This assumption is reasonable and valid in many practical applications, especially when calibration points are sufficiently dense.

[0087] The target error model consists of three independent piecewise linear functions:

[0088] First piecewise linear mapping relationship (angle to pressure error): ,in This function is the core of pressure error compensation; it establishes a direct functional relationship between pressure correction measurement error and spatial direction (angle).

[0089] Second piecewise linear mapping relationship (angle to pressure center error): ,in It is important to note that, It is a two-dimensional vector. Therefore, this linear mapping can actually be decomposed into linear mappings of the two components (X and Y) of the vector respectively, that is... and .

[0090] Third piecewise linear mapping relationship (angle to radial distance): ,in This function describes how the true radial distance of the calibration point varies with the angle. For a rectangular boundary, this function is obviously not constant. The purpose of this mapping is to estimate a desired or true radial distance, i.e., a radial reference distance value, for the test point at any angle during the compensation step, for subsequent fine-tuning compensation.

[0091] For each angle interval ( ) and interval Each of them requires calculating a set of independent slopes. and intercept Taking radial distance mapping as an example, in the interval The formulas for calculating the slope and intercept within the interval are:

[0092] slope

[0093] intercept

[0094] For pressure error and pressure center error Mapping coefficients ( )and( The calculation method is exactly the same; you only need to change the formula. Replace with the corresponding or (and its components) are sufficient.

[0095] By calculating all eight angle intervals and By obtaining the parameters, a complete target error model is obtained. This model stores the spatial distribution information of the entire measurement system error field in a parameterized form.

[0096] For example, the comprehensive data table generated by S220 is used to calculate the parameters of the target error model. The first angle interval will be calculated in detail, i.e. arrive between( The parameters of ).

[0097] The data points for this interval are:

[0098] Point 1:

[0099] Point 2:

[0100] Angle difference .

[0101] Calculate the parameters of the third piecewise linear mapping (radial distance). :

[0102] radial distance difference mm.

[0103] slope mm / degree.

[0104] intercept mm.

[0105] Therefore, within this interval, .

[0106] Calculate the parameters of the first piecewise linear mapping (pressure error). :

[0107] Pressure correction measurement error difference .

[0108] slope (dimensionless) / degree.

[0109] intercept .

[0110] Therefore, within this interval, .

[0111] Calculate the parameters of the second piecewise linear mapping (pressure center error). Here, we need to calculate the X and Y components separately.

[0112] X component: mm.

[0113] slope mm / degree.

[0114] intercept mm.

[0115] Y component: mm.

[0116] slope mm / degree.

[0117] intercept mm.

[0118] Therefore, within this interval, , .

[0119] Repeating the above calculations for all eight angle intervals yields a complete set of parameters, which constitutes the final target error model. For example, for the interval... It is also necessary to calculate a new set of calculations. Ultimately, the model will contain 8 parameter values 8 8 8 These parameters (etc.) are stored for use in the next step of real-time compensation.

[0120] S300: Compensates for real-time measurement data.

[0121] Once the error model is established, the system can enter real-time compensation mode. In this mode, for any new measurement, the system will perform a series of calculations to correct the original measurement results using pre-stored model parameters.

[0122] The process first requires acquiring real-time measurement data from the measurement system for a point to be measured, including a measured pressure value. And the coordinates of the center of pressure to be measured .

[0123] Next, based on the target error model, the pressure compensation error, pressure center compensation error, and corresponding radial reference distance value corresponding to the measured point are calculated. This step is the core of the compensation algorithm; it first requires determining the position of the measured point in the error field. This is done by calculating the polar angle value of the measured point. That's how it's done. Once the angle is determined... You can then find the angle range to which it belongs. Then, using the model parameters corresponding to that interval ( and The three key error / parameter estimates at this specific angle are calculated using linear interpolation:

[0124] Estimated pressure compensation error: .

[0125] Estimated pressure center compensation error: .

[0126] Estimated radial reference distance: .

[0127] Finally, based on the calculated compensation error and reference value, the measured pressure value and the measured coordinates of the pressure center are compensated to obtain a compensated pressure value and a compensated pressure center coordinate. This step is the process of applying the compensation value to correct the original data. The compensation formula it is based on is essentially the inverse operation of the error definition formula in S210.

[0128] Compensated pressure value The calculation formula is: In this formula, This is the original pressure measurement. The denominator is the estimated local calibration coefficient. It is the reference calibration coefficient of the center point. This is the pressure compensation error obtained from interpolation in the model. In addition, a radial distance correction factor is introduced into the formula. ,in It is the estimated true radial distance (i.e., the radial reference distance value) obtained by interpolation from the model, while It is the modulus of the measured coordinates (i.e., the radial distance value to be measured). This correction factor takes into account the second-order effect that the error may also be related to the radial distance, making the compensation more accurate.

[0129] Coordinates of the pressure center after compensation The calculation formula is: This formula means that, in the original measured coordinates... Based on this, a corrected compensation vector is added. The compensation vector is the basic error vector interpolated by the model. It is also multiplied by a radial distance correction factor. Finally, subtract the reference deviation of the center point. Through the calculations using these two formulas, the system output will no longer be the original measurement value with significant spatial distortion error, but rather a more accurate and closer-to-true pressure and pressure center data after precise compensation.

[0130] For example, suppose the system obtains a set of real-time measurement data at a certain moment: the measured pressure value. N, coordinates of the center of pressure to be measured. mm.

[0131] Calculate the angle and radial measurement values ​​of the point to be measured:

[0132] Polar angle value to be measured .

[0133] Radial distance value to be measured mm.

[0134] Find the interval and interpolate to calculate the compensation error / reference value:

[0135] Angle 63.43 is located in the first angle interval. Therefore, the model parameters for this interval are calculated using the parameters from the S230 example.

[0136] Predicted radial reference distance value mm.

[0137] Predicted pressure compensation error .

[0138] Predicted pressure center compensation error :

[0139] mm.

[0140] mm.

[0141] so, mm.

[0142] The final result is calculated using the compensation formula:

[0143] The reference parameters in S210 are also required: , mm.

[0144]

[0145] N (The example data here has been adjusted to ensure the rationality of the physical meaning. In actual applications, the parameters and formulas will be optimized to ensure robustness).

[0146]

[0147]

[0148]

[0149] mm.

[0150] Ultimately, the system output a compensated pressure value of 98.23 N, with the compensated pressure center coordinates at (63.69, 125.80) mm. Compared to the original measured value (101.00 N, (60.0, 120.0) mm), this result corrects the pressure value to be closer to the true value. The pressure center coordinates were corrected in both the positive X and positive Y directions. The direction and magnitude of this correction were dynamically calculated by a pre-established error model based on the current measurement position.

[0151] This application also provides a compensation device based on the pressure and pressure center measurement accuracy of a weighing sensor. This device can be a server, personal computer (PC), tablet computer, etc. The device may include a processor, memory, and a communication interface.

[0152] The processor can be a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a programmable logic device (FPGA), or other chips or hardware with processing capabilities.

[0153] The memory can be volatile memory (e.g., random access memory, RAM) and / or non-volatile memory (e.g., read-only memory, ROM, or flash memory). The memory is used to store program instructions, which the processor executes to implement the steps in the foregoing method embodiments.

[0154] The communication interface is used to communicate with external devices, such as receiving raw measurement data from a hardware front-end consisting of multiple weighing sensors and a data acquisition card.

[0155] In one specific embodiment, the device implements the following functional modules by executing instructions stored in the memory:

[0156] A data acquisition module is used to receive calibration data and real-time measurement data from external measurement hardware via a communication interface.

[0157] A model building module is responsible for performing all calculations in S100, S210, S220 and S230, including error calculation, coordinate transformation and calculation of piecewise linear mapping model parameters, and storing the calculated model parameters in memory.

[0158] A real-time compensation module is responsible for performing all calculations in the S300. It receives real-time measurement data, calls the model parameters stored in the model building module, performs interpolation and compensation calculations, and outputs the final compensated pressure value and pressure center coordinates.

[0159] Those skilled in the art will understand that the foregoing structure is merely illustrative, and the device may also include more or fewer components, or have a different configuration than the foregoing structure.

[0160] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, can perform the steps described in any of the foregoing method embodiments. The storage medium can be any electronic, magnetic, optical, or other physical device capable of storing program code, such as ROM, RAM, flash memory, hard disk, optical disk, etc.

[0161] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0162] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit described above can be implemented in hardware.

[0163] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0164] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit described above can be implemented in hardware.

[0165] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A compensation method for the measurement accuracy of pressure and pressure center based on a weighing sensor, characterized in that, The method includes: Acquire calibration data of a measurement system at multiple preset calibration points. The measurement system consists of at least three load cells. The calibration data includes pressure measurement values, pressure center measurement coordinates, and corresponding true pressure values ​​and pressure center true value coordinates at the geometric center calibration point and each of the other preset calibration points. Based on the measured values ​​and true values ​​at the geometric center calibration point and the remaining preset calibration points, the measurement error at the geometric center calibration point and the pressure correction measurement error and pressure center correction measurement error at the remaining preset calibration points are determined. This step includes: for the i-th preset calibration point, its pressure correction measurement error... Determined in the following manner: ,in, The pressure measurement value at the i-th preset calibration point. The true pressure value at the i-th preset calibration point. The pressure measurement value at the geometric center calibration point. The true pressure value at the geometric center calibration point; for the i-th preset calibration point, the pressure center correction measurement error. Determined in the following manner: ,in, The pressure center measurement coordinates of the i-th preset calibration point are given. Let i be the true coordinates of the pressure center at the i-th preset calibration point. The true coordinates of the pressure center of the geometric center calibration point; Based on the Cartesian coordinates of the remaining preset calibration points in the coordinate system of the measurement system, determine the radial distance and polar angle value at each preset calibration point; A target error model is established, which includes at least a first piecewise linear mapping relationship characterizing the pressure correction measurement error and the polar angle value, a second piecewise linear mapping relationship characterizing the pressure center correction measurement error and the polar angle value, and a third piecewise linear mapping relationship characterizing the radial distance value and the polar angle value. The measurement system acquires real-time measurement data for the point to be measured, including the measured pressure value and the measured coordinates of the center of the pressure to be measured. Based on the target error model, the pressure compensation error, pressure center compensation error, and corresponding radial reference distance value corresponding to the test point are calculated. This step includes: calculating the polar angle value to be measured corresponding to the pressure center measurement coordinates of the test point; determining the pressure compensation error based on the polar angle value to be measured in the first piecewise linear mapping relationship; determining the pressure center compensation error based on the polar angle value to be measured in the second piecewise linear mapping relationship; and determining the radial reference distance value based on the polar angle value to be measured in the third piecewise linear mapping relationship. Based on the measurement error of the geometric center calibration point, the pressure compensation error, the pressure center compensation error, and the radial reference distance value, the measured pressure value and the measured coordinates of the pressure center are compensated to obtain the compensated pressure value and the compensated pressure center coordinates.

2. The method according to claim 1, characterized in that, The step of compensating for the measured pressure value and the measured coordinates of the center of the measured pressure includes: The compensated pressure value is calculated based on the measured pressure value, the measured pressure value and true value of the geometric center calibration point, the pressure compensation error, the radial reference distance value, and the radial distance value determined according to the modulus of the measured coordinates of the pressure center. The compensated pressure center coordinates are calculated based on the measured coordinates of the pressure center to be measured, the measured and true values ​​of the pressure center at the geometric center calibration point, the pressure center compensation error, the radial reference distance value, and the radial distance value to be measured determined according to the modulus of the measured coordinates of the pressure center to be measured.

3. The method according to claim 2, characterized in that, The compensated pressure value Determined in the following manner: ,in, The measured value of the pressure to be measured. This is the pressure compensation error. The radial reference distance value, The radial distance value to be measured is determined based on the modulus of the coordinates of the center of the pressure to be measured.

4. The method according to claim 2, characterized in that, The compensated pressure center coordinates Determined in the following manner: ,in, The coordinates of the center of the pressure to be measured are given. To compensate for the pressure center error, The radial reference distance value, The radial distance value to be measured is determined based on the modulus of the coordinates of the center of the pressure to be measured.

5. The method according to claim 1, characterized in that, The plurality of preset calibration points include a central calibration point located at the origin of the coordinate system of the measurement system, and a plurality of non-central calibration points symmetrically distributed along at least two mutually orthogonal coordinate axes.

6. The method according to claim 1, characterized in that, The origin of the coordinate system of the measurement system is the geometric centroid of the at least three weighing sensors.

7. A compensation device for pressure and pressure center measurement accuracy based on a weighing sensor, characterized in that, The device includes: At least three load cells are used to form a measurement system; A memory used to store program instructions; A processor for executing the program instructions to implement the method as described in any one of claims 1-6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-6.

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