High-precision steering engine calibration method and system

Abstract

The invention provides a high-precision steering engine calibration method. The high-precision steering engine calibration method comprises the following steps: firstly, constructing an original data point set for steering engine angle calibration; then, on the basis of the original data point set, a globally smooth calibration curve is generated through fitting of a cubic spline interpolation algorithm; then determining a boundary calibration function for compensating the feedback angle of the steering engine outside the effective range of the calibration curve; and finally, based on the calibration curve and the boundary calibration function, performing mapping correction on a potentiometer angle value fed back in real time in the operation process of the steering engine so as to output a calibrated high-precision angle value. According to the high-precision steering engine calibration method provided by the invention, the polynomial calibration coefficient of each segment is output according to the fitted cubic spline curve, a real-time table look-up and calculation mechanism is established in the steering engine controller based on the coefficient, and meanwhile, the feedback angle of the steering engine potentiometer is jointly corrected in real time by utilizing a boundary processing mode, so that the calibration accuracy of the steering engine is improved. And high-precision steering engine angle calibration is obtained.

Description

Technical Field

[0001] This invention belongs to the field of servo control technology, and in particular relates to a high-precision servo calibration method and system. Background Technology

[0002] A servo motor is a precision angular displacement actuator used to accurately adjust the attitude, heading, and flight path of an aircraft. The servo motor's angular control accuracy directly affects the performance of the entire system. Traditional servos use built-in potentiometers to provide feedback on the current angular position. However, due to the nonlinear characteristics of the potentiometer itself, manufacturing tolerances, wear, and other factors, a nonlinear error exists between the potentiometer feedback value and the actual output shaft angle. Currently widely used methods such as linear calibration, improved piecewise linear calibration, and high-order polynomial fitting generally suffer from insufficient accuracy, making it difficult to meet the stringent requirements of modern high-precision applications for servo motor control accuracy. Therefore, it is necessary to improve servo motor calibration methods. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and propose a high-precision servo motor calibration method and system.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A high-precision servo motor calibration method includes the following steps: S1. Construct a raw data point set for servo angle calibration, wherein the raw data point set includes the servo potentiometer feedback angle value and the corresponding actual deflection angle value; S2. Based on the original data point set, a globally smooth calibration curve is generated by fitting a cubic spline interpolation algorithm. The calibration curve is composed of multiple piecewise cubic polynomial functions with continuous first and second derivatives at the connection points. S3. Determine a boundary calibration function for compensating the servo feedback angle outside the effective range of the calibration curve, wherein the boundary calibration function maintains first derivative continuity with the calibration curve at the boundary point; S4. Based on the calibration curve and the boundary calibration function, the potentiometer angle value fed back in real time during the operation of the servo motor is mapped and corrected to output a high-precision calibrated angle value.

[0005] Furthermore, the steps for constructing the original data point set include: within the effective angular range of the servo motor, collecting n+1 discrete calibration points using a testing instrument, and recording a pair of data points for each calibration point. , ),in This is the potentiometer feedback value. For the actual angle values ​​obtained through high-precision measuring devices, all Satisfies a strictly monotonically increasing relationship This forms an ordered set of data points. .

[0006] Furthermore, the step of fitting and generating a globally smooth calibration curve specifically includes: dividing the data point set into n intervals, and for each interval... Construct a cubic polynomial As a calibration curve segment: Among them, the coefficient , , , The constraints imposed by a system of linear equations are determined by solving the system of equations. a. Interpolation conditions: for each polynomial Data points must pass through the endpoints of its interval, i.e. and ; b. First derivative continuity condition: at internal nodes At this point, the first derivatives of adjacent polynomials are equal. ; c. Second derivative continuity condition: at internal nodes At that point, the second derivatives of adjacent polynomials are equal. .

[0007] Furthermore, the steps for determining the boundary calibration function include: For values ​​below the minimum calibration point Feedback angle range Using a first-order polynomial function on the left boundary Perform calibration; for points above the maximum calibration point Feedback angle range Using a first-order polynomial function on the right boundary Calibration is performed; among which, the slope parameter Take the calibration curve at the starting point The first derivative value at slope parameter Take the calibration curve at the endpoint The first derivative value at .

[0008] Furthermore, the intercept parameter of the first-order polynomial function on the left boundary By point Substitution and utilize The relationship is obtained, that is The intercept parameter of the right boundary first-order polynomial function; By point Substitution and utilize The relationship is obtained, that is .

[0009] Furthermore, the potentiometer angle value is fed back in real time. x The steps for mapping correction include: determining the real-time feedback angle value. x The interval in which it is located; if According to x The specific interval to which it belongs Call the corresponding cubic polynomial Calculate the calibrated angle value; if Then the left boundary first-order polynomial function is called. Calculate the calibrated angle value; if Then the right boundary first-order polynomial function is called. Calculate the calibrated angle value.

[0010] A high-precision servo motor calibration system is provided for implementing the aforementioned high-precision servo motor calibration method. The system includes: The data acquisition module is used to acquire and construct the original data point set; The data processing module is used to execute the cubic spline interpolation algorithm to generate the global smooth calibration curve and calculate the parameters of the boundary calibration function; The real-time calibration module is used to receive real-time feedback angle values, perform real-time mapping calculations based on the calibration curve and boundary calibration function, and output the calibrated angle values.

[0011] Furthermore, the real-time calibration module is integrated inside the servo controller and includes a storage unit for pre-storing all piecewise cubic polynomials. coefficient set and the parameters of the boundary calibration function .

[0012] Compared with existing technologies, the present invention has the following advantages: The high-precision servo calibration method provided by this invention outputs piecewise polynomial calibration coefficients based on the fitted cubic spline curve, and establishes a real-time lookup table and calculation mechanism in the servo controller based on these coefficients. At the same time, it uses boundary processing to jointly correct the feedback angle of the servo potentiometer in real time, thereby obtaining high-precision servo angle calibration. Attached Figure Description

[0013] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1A schematic diagram of the calibration method flow for this invention. Detailed Implementation

[0014] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0015] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0016] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] A high-precision servo motor calibration method includes the following steps: S1. Construct a raw data point set for servo angle calibration, wherein the raw data point set includes the servo potentiometer feedback angle value and the corresponding actual deflection angle value; S2. Based on the original data point set, a globally smooth calibration curve is generated by fitting a cubic spline interpolation algorithm. The calibration curve is composed of multiple piecewise cubic polynomial functions with continuous first and second derivatives at the connection points. That is, in each sub-interval formed by adjacent calibration points, an independent cubic polynomial function is used to describe the angle mapping relationship. To ensure that the entire curve is smooth globally, these piecewise polynomials have equal function values ​​at their connection points (i.e., internal calibration points), and both the first derivative (representing the trend of change) and the second derivative (representing the rate of change of the trend of change) remain continuous. S3. Determine a boundary calibration function for compensating the servo feedback angle outside the effective range of the calibration curve, wherein the boundary calibration function maintains first derivative continuity with the calibration curve at the boundary point; To achieve smooth calibration of the servo angle across the entire range, and to avoid calibration within the valid calibration data range [x0, x...] n An angle jump occurs at the boundary of the curve, and this invention optimizes the boundary region of the fitted curve. The specific implementation steps are as follows: 1. First, define the boundary calibration function: For angle values ​​that exceed the range of the main calibration curve, use a first-order polynomial (linear function) for calibration.

[0019] For feedback angles smaller than the minimum calibration point x0 (i.e., x < x0), the left boundary calibration function is defined as: Y_L(x) = k0·x + e0 For values ​​greater than the maximum calibration point x n Feedback angle (i.e., x > x) n The right boundary calibration function is defined as: Y_R(x) = k1·x + e1 2. Determine the slope parameters (k0, k1): To ensure a smooth transition from the main calibration curve to the outer region, the slope of the boundary calibration function should be consistent with the slope (first derivative) of the tangent line to the main calibration curve at the boundary point. That is: The slope k0 of the left boundary is equal to the first derivative of the principal cubic spline curve at the starting point x0: k0 = S0′(x0) The slope k1 of the right boundary is equal to the principal cubic spline curve at the endpoint x. n The first derivative value at: k1 = S n ₋1′(x n This method guarantees the first-order continuity of the calibration function at the boundary points (C). 1 (Continuous), meaning the tangential direction transitions smoothly without abrupt changes.

[0020] 3. Determine the constant term parameters (e0, e1): After the slope is determined, the constant term (intercept) is determined by forcing the boundary calibration function to be equal to the function value of the main calibration curve at the boundary points, in order to ensure zero-order continuity (C). 0 (Continuous). That is: For the left boundary, substituting the boundary point (x0, y0) into Y_L(x) and combining it with S0(x0) = y0, we get: e0 = y0 - k0·x0 For the right boundary, the boundary point (x) n , y n Substitute Y_R(x) into S and combine it with S n ₋1(x n ) = y n Solving for e, we get: e1 = y n - k1·x n By following the steps above, the two calibration functions outside the boundary can be uniquely determined. This method ensures that the servo's calibrated output angle is continuous and smooth throughout the entire domain at any possible feedback angle, effectively improving the stability and reliability of control.

[0021] S4. Based on the calibration curve and the boundary calibration function, the potentiometer angle value fed back in real time during the operation of the servo motor is mapped and corrected to output a high-precision calibrated angle value.

[0022] The steps for constructing the original data point set include: within the effective angular range of the servo motor, collecting n+1 discrete calibration points using a testing instrument, and recording a pair of data points for each calibration point. , ),in This is the potentiometer feedback value. For the actual angle values ​​obtained through high-precision measuring devices, all Satisfies a strictly monotonically increasing relationship This forms an ordered set of data points. .

[0023] The steps for fitting and generating a globally smooth calibration curve specifically include: dividing the data point set into n intervals, and for each interval... Construct a cubic polynomial As a calibration curve segment: Among them, the coefficient , , , The constraints imposed by a system of linear equations are determined by solving the system of equations. a. Interpolation conditions: for each polynomial Data points must pass through the endpoints of its interval, i.e. and ; b. First derivative continuity condition: at internal nodes At this point, the first derivatives of adjacent polynomials are equal. ; c. Second derivative continuity condition: at internal nodes At that point, the second derivatives of adjacent polynomials are equal. The generated curve is composed of multiple cubic curve segments connected end to end, and at each connection point, a smooth transition is achieved between the function itself, the slope of the tangent (first derivative), and the curvature (second derivative), fundamentally avoiding jumps and abrupt changes in the angle output value.

[0024] The steps for determining the boundary calibration function include: For values ​​below the minimum calibration point Feedback angle range Using a first-order polynomial function on the left boundary Perform calibration; for points above the maximum calibration point Feedback angle range Using a first-order polynomial function on the right boundary Calibration is performed; among which, the slope parameter Take the calibration curve at the starting point The first derivative value at slope parameter Take the calibration curve at the endpoint The first derivative value at .

[0025] The intercept parameter of the first-order polynomial function on the left boundary By point Substitution and utilize The relationship is obtained, that is The intercept parameter of the right boundary first-order polynomial function; By point Substitution and utilize The relationship is obtained, that is .

[0026] For real-time feedback potentiometer angle value x The steps for mapping correction include: determining the real-time feedback angle value. x The interval in which it is located; if According to x The specific interval to which it belongs Call the corresponding cubic polynomial Calculate the calibrated angle value; if Then the left boundary first-order polynomial function is called. Calculate the calibrated angle value; if Then the right boundary first-order polynomial function is called. Calculate the calibrated angle value.

[0027] The high-precision servo calibration method provided by this invention outputs piecewise polynomial calibration coefficients based on the fitted cubic spline curve, and establishes a real-time lookup table and calculation mechanism in the servo controller based on these coefficients. At the same time, it uses boundary processing to jointly correct the feedback angle of the servo potentiometer in real time, thereby obtaining high-precision servo angle calibration.

[0028] The following provides a high-precision servo motor calibration system for implementing the above-mentioned high-precision servo motor calibration method. The system includes: The data acquisition module is used to acquire and construct the original data point set; The data processing module is used to execute the cubic spline interpolation algorithm to generate the global smooth calibration curve and calculate the parameters of the boundary calibration function; The real-time calibration module receives real-time feedback angle values ​​and performs real-time mapping calculations based on the calibration curve and boundary calibration function, outputting the calibrated angle values. The real-time calibration module is integrated into the servo controller and includes a storage unit for pre-storing all piecewise cubic polynomials. coefficient set and the parameters of the boundary calibration function .

[0029] The aforementioned high-precision servo calibration system mainly comprises three core units: a test instrument for acquiring raw data points (data acquisition module), a cubic spline interpolation algorithm fitting stage and boundary region processing method (data processing module), and a servo segment calibration section (real-time calibration module). Specifically, in data acquisition module 1, data is acquired from the servo within its effective range of motion. Then, in data processing module 2, cubic spline interpolation fitting is performed on the acquired data points. Finally, real-time calibration is performed in real-time calibration module 3.

[0030] The specific implementation method for data acquisition is as follows: by pausing at multiple angle points, the feedback voltage of the servo motor's built-in potentiometer is simultaneously acquired using a testing instrument (and converted into angle values). (and the actual shaft angle value measured by devices such as high-precision encoders) To form a data point set As an optimized implementation, the density of calibration points can be increased in areas of severe nonlinearity (such as the ends of the stroke) based on a prior estimate or preliminary scan of the servo's nonlinearity. With smaller intervals, the density of calibration points should be appropriately reduced in areas with good linearity (such as the middle of the stroke). (Large intervals) to achieve non-uniform point distribution, thereby optimizing calibration efficiency.

[0031] The specific implementation method for curve fitting and boundary handling is as follows: in each sub-interval Constructing a cubic polynomial By solving for all interpolation conditions, derivative continuity conditions, and natural boundary conditions... A system of linear equations, uniquely determining all coefficients. Subsequently, the calibration curve at the boundary points was calculated. and The first derivative value at and , respectively, serve as the slopes of the left and right boundary calibration functions. and Then, based on the boundary point coordinates... and Calculate the intercept and Thus, to fully determine and .

[0032] The specific implementation method for real-time calibration is as follows: All piecewise polynomial coefficients and boundary function parameters obtained from the solution are stored in the non-volatile memory of the servo controller, and a calibration parameter table is established. When the servo is running, the controller reads the potentiometer feedback value in real time. x First, determine x The interval it is located in: If x falls on Within the interval, the specific sub-interval is located. Read the corresponding coefficients from the parameter table. and substitute The formula calculates the precise angle value.

[0033] like Then the left boundary function is called. Perform the calculation.

[0034] like Then the right boundary function is called. Calculations are performed. Through the above process, high-precision, smooth, and real-time correction of the original potentiometer feedback value can be achieved.

[0035] This invention introduces a cubic spline interpolation algorithm to construct a calibration curve, fundamentally overcoming the inherent defects of traditional linear or piecewise linear calibration methods that struggle to accurately fit the nonlinear characteristics of potentiometers. This achieves a leap in calibration accuracy from "approximate" to "precise." Furthermore, the algorithm ensures continuous first and second derivatives at the connection points of the curve, resulting in extremely smooth changes in the angle output signal. This effectively eliminates control command chattering or overshoot that may occur with traditional methods, significantly improving the dynamic response performance and control stability of servos in high-end applications such as aircraft.

[0036] Meanwhile, special handling is provided for the boundary region of the calibration curve. By matching the slope of the first-order polynomial calibration function outside the boundary with the derivative of the boundary point of the main curve, a smooth and seamless transition from the effective range to the outer region is ensured, completely avoiding the risk of angular jumps at the boundary points. In addition, combined with a non-uniform point distribution optimization strategy, this invention can optimize data acquisition efficiency while ensuring or even improving the overall calibration accuracy, making the method high in accuracy, smoothness, and reliability.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision servo motor calibration method, characterized in that, Includes the following steps: S1. Construct a raw data point set for servo angle calibration, wherein the raw data point set includes the servo potentiometer feedback angle value and the corresponding actual deflection angle value; S2. Based on the original data point set, a globally smooth calibration curve is generated by fitting a cubic spline interpolation algorithm. The calibration curve is composed of multiple piecewise cubic polynomial functions with continuous first and second derivatives at the connection points. S3. Determine a boundary calibration function for compensating the servo feedback angle outside the effective range of the calibration curve, wherein the boundary calibration function maintains first derivative continuity with the calibration curve at the boundary point; S4. Based on the calibration curve and the boundary calibration function, the potentiometer angle value fed back in real time during the operation of the servo motor is mapped and corrected to output a high-precision calibrated angle value.

2. The high-precision servo motor calibration method according to claim 1, characterized in that, The steps for constructing the original data point set include: within the effective angular range of the servo motor, collecting n+1 discrete calibration points using a testing instrument, and recording a pair of data points for each calibration point. , ),in This is the potentiometer feedback value. For the actual angle values ​​obtained through high-precision measuring devices, all Satisfies a strictly monotonically increasing relationship This forms an ordered set of data points. .

3. The high-precision servo motor calibration method according to claim 2, characterized in that, The steps for fitting and generating a globally smooth calibration curve specifically include: dividing the data point set into n intervals, and for each interval... Construct a cubic polynomial As a calibration curve segment: Among them, the coefficient , , , The constraints imposed by a system of linear equations are determined by solving the system of equations. a. Interpolation conditions: for each polynomial Data points must pass through the endpoints of its interval, i.e. and ; b. First derivative continuity condition: at internal nodes At this point, the first derivatives of adjacent polynomials are equal. ; c. Second derivative continuity condition: at internal nodes At this point, the second derivatives of adjacent polynomials are equal. .

4. The high-precision servo motor calibration method according to claim 3, characterized in that, The steps for determining the boundary calibration function include: For values ​​below the minimum calibration point Feedback angle range Using a first-order polynomial function on the left boundary Perform calibration; for points above the maximum calibration point Feedback angle range Using a first-order polynomial function on the right boundary Calibration is performed; among which, the slope parameter Take the calibration curve at the starting point The first derivative value at slope parameter Take the calibration curve at the endpoint The first derivative value at .

5. The high-precision servo motor calibration method according to claim 4, characterized in that: The intercept parameter of the first-order polynomial function on the left boundary By point Substitution and utilize The relationship is obtained, that is The intercept parameter of the right boundary first-order polynomial function; By point Substitution and utilize The relationship is obtained, that is .

6. The high-precision servo motor calibration method according to claim 1, characterized in that, For real-time feedback potentiometer angle value x The steps for mapping correction include: determining the real-time feedback angle value. x The interval in which it is located; if According to x The specific interval to which it belongs Call the corresponding cubic polynomial Calculate the calibrated angle value; if Then the left boundary first-order polynomial function is called. Calculate the calibrated angle value; if Then the right boundary first-order polynomial function is called. Calculate the calibrated angle value.

7. A high-precision servo motor calibration system for implementing the high-precision servo motor calibration method according to any one of claims 1 to 6, characterized in that, The system includes: The data acquisition module is used to acquire and construct the original data point set; The data processing module is used to execute the cubic spline interpolation algorithm to generate the global smooth calibration curve and calculate the parameters of the boundary calibration function; The real-time calibration module is used to receive real-time feedback angle values, perform real-time mapping calculations based on the calibration curve and boundary calibration function, and output the calibrated angle values.

8. The system according to claim 7, characterized in that, The real-time calibration module is integrated inside the servo controller and includes a storage unit for pre-storing all piecewise cubic polynomials. coefficient set and the parameters of the boundary calibration function .

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