An overload attitude switching control method of an unmanned aerial vehicle

Abstract

The application provides a method for overload and attitude hybrid control and mutual switching conversion of unmanned aerial vehicle, which measures the pitch angle and vertical overload by a gyroscope and an accelerometer respectively, and then forms a pitch angle error signal and an overload error signal according to an instruction; then carries out odd transform and exponential square root hybrid transform respectively to obtain an error comprehensive signal; then carries out odd transform, odd softening transform, and cubic and linear mixed anti-saturation segmented integration to obtain a non-linear translation signal of error and a hybrid differential signal of error, and then obtains a pitch attitude control law and a pitch overload control law through the comprehensive of the above signals; finally, when the pitch angle error is small, the attitude control is adopted, and when the pitch angle error is large, the overload instruction is generated according to the overload error, and the overload control is switched to, so that the fast and stable switching control of the unmanned aerial vehicle is realized.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) stability and control, and more specifically, to a method for the hybrid switching and control of overload and attitude of an UAV. Background Technology

[0002] Unmanned aerial vehicle (UAV) control is widely used not only in civilian drones but also plays a crucial role in the flight guidance of military aircraft. Currently, most civilian aircraft employ attitude control due to its high stability and reliability. However, in certain military applications, such as guidance systems, UAVs require strong maneuverability, making overload control the preferred method for interception. Even for such aircraft, attitude control remains superior during level flight before reaching the target. Therefore, neither attitude control nor overload control alone can meet these requirements. Based on this background, this invention proposes a hybrid control method that can freely switch between attitude and overload control, possessing significant engineering application value.

[0003] It should be noted that the information in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an overload attitude switching control method for unmanned aerial vehicles, thereby overcoming the problems of incompatibility and difficulty in switching between attitude control and overload control caused by the limitations and defects of related technologies.

[0005] According to one aspect of the present invention, an overload attitude switching control method for an unmanned aerial vehicle is provided, comprising the following steps:

[0006] Step S10: Install an angle-measuring gyroscope on the unmanned aerial vehicle (UAV) to measure the pitch angle signal. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Then, perform an odd-order transformation to obtain the odd-order pitch angle error signal. Next, perform an exponential square root hybrid transformation on the pitch angle error signal to obtain the exponential square root pitch angle error signal. Finally, superimpose the pitch angle error signal, the odd-order pitch angle error signal, and the exponential square root pitch angle error signal to obtain the comprehensive pitch angle error signal.

[0007] Step S20: The pitch angle error signal is obtained by comparing the integrated pitch angle error signal with the nonlinear translation signal of the pitch angle error; then, odd transformation and odd softening transformation are performed respectively to obtain the odd transformation signal and the odd softening transformation signal of the pitch angle error, and then they are superimposed to obtain the nonlinear translation rate signal of the pitch angle error; then, a cubic and linear mixed anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the pitch angle error.

[0008] Step S30: Solve the pitch angle differential coefficient signal based on the pitch angle error signal; then solve the pitch angle error mixed differential signal based on the nonlinear translation signal of the pitch angle error, the comprehensive pitch angle error signal, and the pitch angle differential coefficient signal; then perform a cubic and linear mixed anti-saturation piecewise integration based on the comprehensive pitch angle error signal to obtain the comprehensive integrated pitch angle error signal; finally, superimpose the pitch angle error signal, the mixed differential pitch angle error signal, the nonlinear translation rate signal of the pitch angle error, the comprehensive pitch angle error signal, and the nonlinear translation signal of the pitch angle error to form the comprehensive pitch attitude control signal.

[0009] Step S40: Based on the flight mission requirements, set the expected overload signal; then install an accelerometer on the unmanned aerial vehicle (UAV) to measure the vertical acceleration of the UAV, and then calculate the vertical overload signal of the UAV. Compare the calculated signal with the expected overload signal to obtain the overload error signal; then perform an odd-order transformation to obtain the odd-order overload error signal; then perform an exponential square root hybrid transformation on the overload error signal to obtain the exponential square root overload error signal; finally, superimpose the overload error signal, the odd-order overload error signal, and the exponential square root overload error signal to obtain the comprehensive overload error signal.

[0010] Step S50: The overload error signal is obtained by comparing the comprehensive overload error signal with the nonlinear translation signal of the overload error; then, odd transformation and odd softening transformation are performed respectively to obtain the odd transformation signal and the odd softening transformation signal of the overload error, which are then superimposed to obtain the nonlinear translation rate signal of the overload error; then, a cubic and linear mixed anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the overload error.

[0011] Step S60: Solve the overload differential coefficient signal based on the overload error signal; then solve the overload error mixed differential signal based on the nonlinear translation signal of the overload error, the comprehensive overload error signal, and the overload differential coefficient signal; then perform a cubic and linear mixed anti-saturation piecewise integration based on the comprehensive overload error signal to obtain the comprehensive overload error signal; finally, superimpose the overload error signal, the mixed differential overload error signal, the nonlinear translation rate signal of the overload error, the comprehensive overload error signal, and the nonlinear translation signal of the overload error to form the pitch overload comprehensive control signal.

[0012] Step S70: Set a switching threshold according to the pitch angle error signal. When the pitch angle error is less than the threshold, the pitch control quantity of the UAV is selected as the pitch attitude comprehensive control signal. When the pitch angle error is greater than the threshold, the pitch angle error is converted into an overload expectation signal, and the UAV pitch control quantity is selected as the pitch overload comprehensive control signal. This realizes the switching of the control law from attitude control to rapid overload control, and achieves stable attitude tracking of the aircraft pitch channel.

[0013] In one exemplary embodiment of the present invention, an angle-measuring gyroscope is installed on the unmanned aerial vehicle (UAV) to measure the pitch angle signal. Then, a desired pitch angle signal is set according to the flight mission, and compared to obtain a pitch angle error signal. An odd-order transformation is then performed to obtain an odd-order pitch angle error signal. Next, an exponential square root hybrid transformation is performed on the pitch angle error signal to obtain an exponential square root pitch angle error signal. Finally, the pitch angle error signal, the odd-order pitch angle error signal, and the exponential square root pitch angle error signal are superimposed to obtain a comprehensive pitch angle error signal, including:

[0014] e1=θ-θ d ;

[0015]

[0016]

[0017] e f =c1e1+c2f1+c3f2;

[0018] Where θ is the pitch angle signal of the unmanned aerial vehicle obtained by measuring the gyroscope, θ d The desired pitch angle signal is set according to the flight mission; e1 is the pitch angle error signal; f1 is the odd-order pitch angle error signal; w is the exponential constant parameter; ε0 is the square root transform constant parameter; f2 is the exponential square root signal of the pitch angle error; c1, c2, and c3 are constant superposition coefficients, e f This is the pitch angle error composite signal.

[0019] In one exemplary embodiment of the present invention, the pitch angle error signal is obtained by comparing the comprehensive pitch angle error signal with the nonlinear translation signal of the pitch angle error; then, odd-order transforms and odd-order softening transforms are performed respectively to obtain the odd-order transformed pitch angle error signal and the odd-order softening transform pitch angle error signal, which are then superimposed to obtain the nonlinear translation rate signal of the pitch angle error; finally, a cubic and linear hybrid anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the pitch angle error, including:

[0020] e f1 (n)=e f(n)-e f0 (n);

[0021] e f2 (n)=(e f (n)-e f0 (n)) 7 / 13 ;

[0022]

[0023]

[0024]

[0025] Where e f1 e is the pitch angle translation error signal; f2 ε1 is the odd-order transform signal of the pitch angle translation error; ε1 is the odd-order softening transform constant parameter, e f3 The pitch angle translation error is represented by an odd-order softened transform signal, where T1, T2, and T3 are constant parameters of the nonlinear translation, and e fd e is the nonlinear translation rate signal of pitch angle error; f0 Let be the nonlinear translation signal of the pitch angle error, a1 be the constant piecewise parameter of the piecewise integration, and T be the time constant of the integration.

[0026] In one exemplary embodiment of the present invention, the pitch angle differential coefficient signal is solved based on the pitch angle error signal; then, the pitch angle error mixed differential signal is solved based on the nonlinear translation signal of the pitch angle error, the comprehensive pitch angle error signal, and the pitch angle differential coefficient signal; next, a cubic and linear mixed anti-saturation piecewise integration is performed on the comprehensive pitch angle error signal to obtain the comprehensive integrated pitch angle error signal; finally, the pitch angle error signal, the mixed differential pitch angle error signal, the nonlinear translation rate signal of the pitch angle error, the comprehensive pitch angle error signal, and the nonlinear translation signal of the pitch angle error are superimposed to form the comprehensive pitch attitude control signal, including:

[0027]

[0028]

[0029]

[0030] u1=k1e1+k2e 1d +k3s1+k4e fd +k5e f +k6e f0 ;

[0031] Where sign() is the sign function, e z For pitch angle differential coefficient signal, e1d s1 is the pitch angle error mixed differential signal; a0 is the constant parameter for piecewise integration; s1 is the pitch angle error integrated signal; k1, k2, k3, k4, k5, and k6 are constant control parameters; and u1 is the pitch attitude integrated control signal.

[0032] In one exemplary embodiment of the present invention, an overload expectation signal is set according to the flight mission requirements; then, an accelerometer is installed on the unmanned aerial vehicle (UAV) to measure the vertical acceleration of the UAV, and then the vertical overload signal of the UAV is calculated and compared with the overload expectation signal to obtain an overload error signal; then, an odd-order transformation is performed to obtain an odd-order overload error signal; then, an exponential square root hybrid transformation is performed on the overload error signal to obtain an exponential square root overload error signal; finally, the overload error signal, the odd-order overload error signal, and the exponential square root overload error signal are superimposed to obtain a comprehensive overload error signal, including:

[0033]

[0034]

[0035]

[0036]

[0037] e g =c a1 e2+c a2 g2+c a3 g2;

[0038] Where a is the vertical acceleration signal of the unmanned aerial vehicle measured by an accelerometer, g is the gravitational acceleration, and n y d To provide the desired overload signal based on the flight mission settings, n y e1 is the vertical overload signal of the aircraft; e2 is the overload error signal; g1 is the odd-order overload error signal; ε a 0 is the constant parameter for the square root transformation, g2 is the square root signal of the overload error exponent; c a1 c a2 c a3 e is a constant superposition coefficient. g This is a comprehensive signal for overload error.

[0039] In one exemplary embodiment of the present invention, an overload translation error signal is obtained by comparing the comprehensive overload error signal with the nonlinear translation signal of the overload error; then, odd-order transforms and odd-order softening transforms are performed respectively to obtain an odd-order transform signal and an odd-order softening transform signal of the overload translation error, which are then superimposed to obtain a nonlinear translation rate signal of the overload error; finally, a cubic and linear hybrid anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the overload error, including:

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] Where e g1 This is the overload translation error signal; e g2 e is the odd-order transform signal of overload translation error; g3 For the odd-order softened transform signal of overload translation error, e gd The nonlinear translation rate signal for overload error; e g0 b1 is the nonlinear translation signal of the overload error, and b1 is the constant piecewise parameter of the piecewise integral.

[0046] In one exemplary embodiment of the present invention, the overload differential coefficient signal is solved based on the overload error signal; then, the overload error mixed differential signal is solved based on the nonlinear translation signal of the overload error, the comprehensive overload error signal, and the overload differential coefficient signal; next, a cubic and linear mixed anti-saturation piecewise integration is performed on the comprehensive overload error signal to obtain the comprehensive overload error signal; finally, the overload error signal, the mixed overload error differential signal, the nonlinear translation rate signal of the overload error, the comprehensive overload error signal, and the nonlinear translation signal of the overload error are superimposed to form the pitch overload comprehensive control signal, including:

[0047]

[0048]

[0049]

[0050] u2=k a1 e2+k a2 e 2d +k a3 s2+k a4 egd +k a5 e g ;

[0051] Where e 2z For overload differential coefficient signal, e 2d s1 is the mixed differential signal of overload error; b0 is the constant parameter of piecewise integration, s2 is the comprehensive integrated signal of overload error; k a1 k a2 k a3 k a4 k a5 k a6 is a constant control parameter, and u2 is the pitch overload integrated control signal.

[0052] In one exemplary embodiment of the present invention, a switching threshold is set according to the pitch angle error signal. When the pitch angle error is less than the threshold, the pitch control quantity of the unmanned aerial vehicle is selected as the pitch attitude comprehensive control signal; when the pitch angle error is greater than the threshold, the pitch angle error is converted into an overload expectation signal, and the pitch control quantity of the unmanned aerial vehicle is selected as the pitch overload comprehensive control signal, realizing the switching of the control law from attitude control to rapid overload control, including:

[0053]

[0054]

[0055] Where a w The switching threshold is a constant parameter, k. w2 ε w1 k w1 is a constant conversion parameter, and u is the pitch control variable of the unmanned aerial vehicle.

[0056] Beneficial effects

[0057] This invention discloses an overload attitude switching control method for unmanned aerial vehicles (UAVs). Its main innovations are as follows: First, under large pitch angle errors, overload control is employed to achieve maximum acceleration maneuvering; while under small pitch angle errors, attitude control is switched to, thus giving the UAV strong stability and reliability in level flight; and during terminal guidance, the advantages of rapid maneuvering via overload control can be utilized. Second, both individual attitude control and overload control only require measuring one signal (attitude or overload). Furthermore, by transforming the error signal, a unified control method for attitude control and overload control is obtained, resulting in a more unified control structure and convenient parameter tuning.

[0058] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0059] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0060] Figure 1 This is a flowchart of an overload attitude switching control method for an unmanned aerial vehicle provided by the present invention;

[0061] Figure 2 This is the pitch angle signal curve of the unmanned aerial vehicle (UAV) provided by the embodiment of the present invention (unit: degrees);

[0062] Figure 3 This is the pitch angle error signal curve of the unmanned aerial vehicle (UAV) provided by the embodiment of the present invention (unit: degrees);

[0063] Figure 4 This is the pitch angular velocity signal curve of the unmanned aerial vehicle (unit: degrees per second) provided by the method in the embodiments of the present invention;

[0064] Figure 5 This is the pitch angle translation error signal curve of the unmanned aerial vehicle (without units) provided by the method in the embodiments of the present invention;

[0065] Figure 6 This is the overload signal curve of the unmanned aerial vehicle (unitless) provided by the method in the embodiments of the present invention;

[0066] Figure 7 This is the pitch control signal curve (unitless) of the unmanned aerial vehicle provided by the embodiment of the present invention. Detailed Implementation

[0067] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention may be practiced with one or more of these specific details omitted, or other methods, components, apparatus, steps, etc., may be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the invention.

[0068] This invention provides a method for hybrid control of overload and attitude control of an unmanned aerial vehicle (UAV) and switching between them. It measures pitch angle and vertical overload using a gyroscope and accelerometer, respectively, and then generates pitch angle error signals and overload error signals based on commands. Next, it performs odd-order transforms and exponential root hybrid transforms to obtain a comprehensive error signal. Then, it performs odd-order transforms, odd-order softening transforms, and performs cubic and linear hybrid anti-saturation piecewise integration to obtain a nonlinear translation signal and a mixed error differential signal. Finally, it synthesizes these signals to obtain the pitch attitude control law and the pitch overload control law. When the pitch angle error is small, attitude control is used; when the pitch angle error is large, an overload command is generated based on the overload error, and the system switches to overload control, thereby achieving rapid and stable switching control of the UAV.

[0069] The overload attitude switching control method for an unmanned aerial vehicle according to the present invention will be further explained and described below with reference to the accompanying drawings. (See reference) Figure 1 As shown, the overload attitude switching control method for an unmanned aerial vehicle may include the following steps:

[0070] Step S10: Install an angle-measuring gyroscope on the UAV to measure the pitch angle signal of the UAV. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Then, perform an odd-order transformation to obtain the odd-order pitch angle error signal. Next, perform an exponential square root hybrid transformation on the pitch angle error signal to obtain the exponential square root pitch angle error signal. Finally, superimpose the pitch angle error signal, the odd-order pitch angle error signal, and the exponential square root pitch angle error signal to obtain the comprehensive pitch angle error signal.

[0071] Specifically, this can be broken down into the following four steps. The first step is to install an angle-measuring gyroscope on the unmanned aerial vehicle (UAV) to measure its pitch angle signal. Then, based on the flight mission, a desired pitch angle signal is set, and the results are compared to obtain the pitch angle error signal, as follows:

[0072] e1=θ-θ d ;

[0073] Where θ is the pitch angle signal of the unmanned aerial vehicle obtained by gyroscope measurement, θ d e1 is the pitch angle expectation signal set according to the flight mission, and e1 is the pitch angle error signal.

[0074] The second step involves performing odd-order transformations on the pitch angle error signal to obtain the odd-order pitch angle error signal as follows:

[0075]

[0076] Where f1 is the odd-order pitch angle error signal.

[0077] The third step is to perform an exponential square root hybrid transform on the pitch angle error signal to obtain the exponential square root signal of the pitch angle error as follows:

[0078]

[0079] Where w is the exponential constant parameter, ε0 is the square root transformation constant parameter, and f2 is the pitch angle error exponential square root signal.

[0080] The fourth step involves superimposing the pitch angle error signal, the odd-order pitch angle error signal, and the square root of the pitch angle error exponent to obtain the comprehensive pitch angle error signal as follows:

[0081] e f 2c1e1+c2f1+c3f2;

[0082] Where c1, c2, and c3 are constant superposition coefficients, e f This is the pitch angle error composite signal.

[0083] Step S20: The pitch angle error signal is obtained by comparing the integrated pitch angle error signal with the nonlinear translation signal of the pitch angle error; then, odd transformation and odd softening transformation are performed respectively to obtain the odd transformation signal and the odd softening transformation signal of the pitch angle error, and then they are superimposed to obtain the nonlinear translation rate signal of the pitch angle error; then, a cubic and linear mixed anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the pitch angle error.

[0084] Specifically, it can be broken down into the following five steps. The first step is to compare the combined pitch angle error signal with the nonlinear translation signal of the pitch angle error to obtain the pitch angle translation error signal as follows:

[0085] e f1 (n)=e f (n)-e f0 (n);

[0086] Where e f1 This is the pitch angle translation error signal.

[0087] The second step involves performing an odd-order transformation on the pitch angle translation error signal to obtain the odd-order transformed pitch angle translation error signal as follows:

[0088] e f2 (n)=(e f (n)-e f0 (n)) 7 / 13 ;

[0089] Where e f2 This is the odd-order transformation signal of the pitch angle translation error.

[0090] The third step involves performing an odd-order softening transform on the pitch angle translation error signal to obtain the following odd-order softening transform signal:

[0091]

[0092] Where ε1 is the odd-order softening transformation constant parameter, e f3 This is the odd-order smoothing transform signal for pitch angle translation error.

[0093] The fourth step involves superimposing the odd-order softened transform signals of the pitch angle translation error to obtain the nonlinear translation rate signal of the pitch angle error, as follows:

[0094]

[0095] Where T1, T2, and T3 are constant parameters of the nonlinear translation, e fd It is the nonlinear translation rate signal of pitch angle error.

[0096] The fifth step involves performing a cubic and linear hybrid anti-saturation piecewise integration on the nonlinear translation rate signal of the pitch angle error, yielding the following nonlinear translation signal of the pitch angle error:

[0097]

[0098] Where ef 0 Let be the nonlinear translation signal of the pitch angle error, a1 be the constant piecewise parameter of the piecewise integration, and T be the time constant of the integration.

[0099] Step S30: Solve the pitch angle differential coefficient signal based on the pitch angle error signal; then solve the pitch angle error mixed differential signal based on the nonlinear translation signal of the pitch angle error, the comprehensive pitch angle error signal, and the pitch angle differential coefficient signal; then perform a cubic and linear mixed anti-saturation piecewise integration based on the comprehensive pitch angle error signal to obtain the comprehensive integrated pitch angle error signal; finally, superimpose the pitch angle error signal, the mixed differential pitch angle error signal, the nonlinear translation rate signal of the pitch angle error, the comprehensive pitch angle error signal, and the nonlinear translation signal of the pitch angle error to form the comprehensive pitch attitude control signal.

[0100] Specifically, it can be broken down into the following four steps. The first step is to solve for the pitch angle difference coefficient signal based on the pitch angle error signal, as follows:

[0101]

[0102] Where sign() is the sign function, e z This is the pitch angle differential coefficient signal.

[0103] The second step involves solving the pitch angle error mixed differential signal based on the nonlinear translation signal of the pitch angle error, the comprehensive pitch angle error signal, and the pitch angle differential coefficient signal, as follows:

[0104]

[0105] Where e 1d It is a mixed differential signal for pitch angle error.

[0106] The third step involves performing a cubic and linear hybrid anti-saturation piecewise integration on the pitch angle error composite signal to obtain the following pitch angle error composite integrated signal:

[0107]

[0108] Where a0 is a constant parameter for piecewise integration, and s1 is the integrated signal of pitch angle error.

[0109] The fourth step involves superimposing the pitch angle error integrated signal, the pitch angle error signal, the pitch angle error mixed differential signal, the nonlinear translation rate signal of the pitch angle error, the pitch angle error integrated signal, and the nonlinear translation signal of the pitch angle error to form the following pitch attitude integrated control signal:

[0110] u1=k1e1+k2e 1d +k3s1+k4e fd +k5e f +k6e f0 ;

[0111] Where k1, k2, k3, k4, k5, and k6 are constant control parameters, and u1 is the pitch attitude integrated control signal.

[0112] Step S40: Based on the flight mission requirements or the pitch angle error, set the expected overload signal; then install an accelerometer on the UAV to measure the vertical acceleration of the UAV, and then calculate the vertical overload signal of the UAV, and compare it with the expected overload signal to obtain the overload error signal; then perform an odd-order transformation to obtain the odd-order overload error signal; then perform an exponential square root hybrid transformation on the overload error signal to obtain the exponential square root overload error signal; finally, superimpose the overload error signal, the odd-order overload error signal, and the exponential square root overload error signal to obtain the comprehensive overload error signal.

[0113] Specifically, this can be broken down into the following five steps. The first step is to install an accelerometer on the unmanned aerial vehicle (UAV), measure the UAV's vertical acceleration, and then calculate the UAV's vertical overload signal as follows:

[0114]

[0115] Where a is the vertical acceleration signal of the unmanned aerial vehicle measured by an accelerometer, g is the gravitational acceleration, and n y This is the vertical overload signal for the aircraft.

[0116] The second step is to set the expected overload signal based on the flight mission requirements or the pitch angle error, and then compare it with the expected overload signal to obtain the overload error signal as follows:

[0117]

[0118] in e1 is the expected overload signal set according to the flight mission or the pitch angle error, and e2 is the overload error signal.

[0119] The third step is to perform an odd-order transform on the overload error signal to obtain the odd-order overload error signal as follows:

[0120]

[0121] Where g1 is the odd-order overload error signal.

[0122] The fourth step is to perform an exponential square root hybrid transform on the overload error signal to obtain the exponential square root signal of the overload error as follows:

[0123]

[0124] Where ε a0 g1 is the constant parameter for the square root transformation, and g2 is the square root signal of the overload error exponent.

[0125] The fifth step involves superimposing the overload error signal, the odd-order overload error signal, and the square root of the overload error exponent to obtain the comprehensive overload error signal as follows:

[0126] e g =c a1 e2+c a2 g2+c a3 g2;

[0127] Where c a1 c a2 c a3 e is a constant superposition coefficient. g This is a comprehensive signal for overload error.

[0128] Step S50: The overload error signal is obtained by comparing the comprehensive overload error signal with the nonlinear translation signal of the overload error; then, odd transformation and odd softening transformation are performed respectively to obtain the odd transformation signal and the odd softening transformation signal of the overload error, which are then superimposed to obtain the nonlinear translation rate signal of the overload error; then, a cubic and linear mixed anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the overload error.

[0129] Specifically, it can be broken down into the following five steps. The first step is to compare the comprehensive overload error signal with the nonlinear translation signal of the overload error to obtain the overload translation error signal as follows:

[0130] e g1 (n)=e g (n)-e g0 (n);

[0131] Where e g1 This is the overload translation error signal.

[0132] The second step involves performing an odd-order transformation on the overload translation error signal to obtain the following odd-order transformed overload translation error signal:

[0133] e g2 (n)=(e g (n)-e g0 (n)) 7 / 13 ;

[0134] Where e g2 This is the odd-order transformation signal of the overload translation error.

[0135] The third step involves performing an odd-order softening transform on the overload translation error signal to obtain the following odd-order softening transform signal:

[0136]

[0137] Where e g3 This is the odd-order softening transform signal for overload translation error.

[0138] The fourth step involves superimposing the odd-order softened transform signals of the overload translation error to obtain the nonlinear translation rate signal of the overload error, as follows:

[0139]

[0140] Where e gd It is a nonlinear translation rate signal for overload error.

[0141] Fifth, perform a piecewise integration of cubic and linear hybrid anti-saturation on the nonlinear translation rate signal of the overload error to obtain the nonlinear translation signal of the overload error as follows:

[0142]

[0143] Where e g0 b1 is the nonlinear translation signal of the overload error, and b1 is the constant piecewise parameter of the piecewise integral.

[0144] Step S60: Solve the overload differential coefficient signal based on the overload error signal; then solve the overload error mixed differential signal based on the nonlinear translation signal of the overload error, the comprehensive overload error signal, and the overload differential coefficient signal; then perform a cubic and linear mixed anti-saturation piecewise integration based on the comprehensive overload error signal to obtain the comprehensive overload error signal; finally, superimpose the overload error signal, the mixed differential overload error signal, the nonlinear translation rate signal of the overload error, the comprehensive overload error signal, and the nonlinear translation signal of the overload error to form the pitch overload comprehensive control signal.

[0145] Specifically, it can be broken down into the following four steps. The first step is to solve for the overload differential coefficient signal based on the overload error signal, as follows:

[0146]

[0147] Where e 2z This is the overload differential coefficient signal.

[0148] The second step involves solving the mixed differential signal of the overload error based on the nonlinear translation signal of the overload error, the comprehensive signal of the overload error, and the differential coefficient signal of the overload error, as follows:

[0149]

[0150] Where e 2d It is a mixed differential signal for overload error.

[0151] The third step involves performing a piecewise integration of cubic and linear components against saturation based on the comprehensive overload error signal, resulting in the following comprehensive overload error signal:

[0152]

[0153] Where b0 is a constant parameter for piecewise integration, and s2 is the overload error integrated signal.

[0154] The fourth step involves superimposing the overload error signal, the mixed differential overload error signal, the nonlinear translation rate signal of the overload error, the comprehensive overload error signal, and the nonlinear translation signal of the overload error onto the integrated overload error signal, forming the pitch overload comprehensive control signal as follows:

[0155] u2=k a1 e2+k a2 e2d +k a3 s2+k a4 e gd +k a5 e g ;

[0156] Where k a1 k a2 k a3 k a4 k a5 k a6 is a constant control parameter, and u2 is the pitch overload integrated control signal.

[0157] Step S70: Set a switching threshold based on the pitch angle error signal. When the pitch angle error is less than the threshold, the pitch control quantity of the UAV is selected as the pitch attitude integrated control signal. When the pitch angle error is greater than the threshold, the pitch angle error is converted into an overload expectation signal, and the UAV pitch control quantity is selected as the pitch overload integrated control signal. This realizes the switching of the control law from attitude control to rapid overload control, achieving stable attitude tracking of the UAV pitch channel as follows:

[0158]

[0159]

[0160] in For the overload expectation signal set according to the pitch angle error, a w The switching threshold is a constant parameter, k. w2 ε w1 k w1 is a constant conversion parameter, and u is the pitch control variable of the unmanned aerial vehicle.

[0161] Case Implementation and Computer Simulation Results Analysis

[0162] In step S10, θ is selected. d =-6, ε0=0.1, c1=5, c2=2, c3=1, w=2.3, the pitch angle signal is obtained as follows Figure 2 As shown; the pitch angle error signal is obtained as follows. Figure 3 As shown; the pitch angular velocity signal is obtained as follows: Figure 4 As shown.

[0163] In step S20, ε1 = 0.3, a1 = 1.2, and T = 0.001 are selected to obtain the pitch angle translation error signal as follows: Figure 5 As shown.

[0164] In step S30, k1 = 2, k2 = 0.8, k3 = 0.5, k4 = 0.2, k5 = 0.3, and k6 = 0.4.

[0165] In step S40, g = 9.8 is selected, and the overload signal is obtained as follows: Figure 6 As shown. In step S50, b1 = 0.7 is selected. In step S60, b0 = 0.5 is selected.

[0166] In step S60, select a w =0.07, the pitch control signal of the unmanned aerial vehicle is obtained as follows Figure 7 As shown.

[0167] Depend on Figure 6 It can be seen that the overload signal of the aircraft reached a maximum of -3 gravitational accelerations; while by Figure 2 It can be seen that the pitch angle reaches the desired command of -6 degrees in about 5 seconds; by Figure 3 It can be seen that the pitch angular velocity is mostly negative, with a peak value of -14; from Figure 7 It can be seen that the final control input oscillates, and the switching occurs around 0.5 seconds, at which point the pitch angle error enters a small error angle; at this point, the overall control effect is good, and the switching does not cause system instability, and even... Figure 7 It is difficult to observe the spikes caused by the switching. Therefore, the experimental results show that the invention is effective and correct, and has great theoretical and engineering application value.

Claims

1. A method for overload attitude switching control of an unmanned aerial vehicle (UAV), Its characteristics include the following steps: Step S10: Install an angle-measuring gyroscope on the UAV to measure the pitch angle signal. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Then, perform an odd-order transformation to obtain the odd-order pitch angle error signal. Next, perform an exponential square root hybrid transformation on the pitch angle error signal to obtain the exponential square root pitch angle error signal. Finally, superimpose the pitch angle error signal, the odd-order pitch angle error signal, and the exponential square root pitch angle error signal to obtain the comprehensive pitch angle error signal as follows: e1=θ-θ d ; and f =c1e1+c2f1+c3f2; Where θ is the pitch angle signal of the unmanned aerial vehicle obtained by gyroscope measurement, θ d The desired pitch angle signal is set according to the flight mission; e1 is the pitch angle error signal; f1 is the odd-order pitch angle error signal; w is the exponential constant parameter; ε0 is the square root transform constant parameter; f2 is the exponential square root signal of the pitch angle error; c1, c2, and c3 are constant superposition coefficients, e f This is the overall pitch angle error signal; Step S20: The pitch angle error signal is obtained by comparing the synthesized pitch angle error signal with the nonlinear translation signal of the pitch angle error; then, odd-order transform and odd-order softening transform are performed respectively to obtain the odd-order transform signal and the odd-order softening transform signal of the pitch angle error, which are then superimposed to obtain the nonlinear translation rate signal of the pitch angle error; finally, a cubic and linear hybrid anti-saturation piecewise integration is performed to obtain the nonlinear translation signal of the pitch angle error as follows: e f1 (n)=e f (n)-e f0 (n); e f2 (n)=(e f (n)-e f0 (n)) 7 / 13 ; Where e f1 e is the pitch angle translation error signal; f2 ε1 is the odd-order transform signal of the pitch angle translation error; ε1 is the odd-order softening transform constant parameter, e f3 The pitch angle translation error is represented by an odd-order softened transform signal, where T1, T2, and T3 are constant parameters of the nonlinear translation, and e fd e is the nonlinear translation rate signal of pitch angle error; f0 Let be the nonlinear translation signal of the pitch angle error, a1 be the constant piecewise parameter of the piecewise integration, and T be the time constant of the integration. Step S30: Solve the pitch angle differential coefficient signal based on the pitch angle error signal; then solve the pitch angle error mixed differential signal based on the nonlinear translation signal of the pitch angle error, the comprehensive pitch angle error signal, and the pitch angle differential coefficient signal; then perform a cubic and linear mixed anti-saturation piecewise integration on the comprehensive pitch angle error signal to obtain the comprehensive integrated pitch angle error signal; finally, superimpose the pitch angle error signal, the mixed differential pitch angle error signal, the nonlinear translation rate signal of the pitch angle error, the comprehensive pitch angle error signal, and the nonlinear translation signal of the pitch angle error to form the comprehensive pitch attitude control signal as follows: u1=k1e1+k2e 1d +k3s1+k4e fd +k5e f +k6e f0 ; Where sign() is the sign function, e z For pitch angle differential coefficient signal, e 1d s1 is the pitch angle error mixed differential signal; a0 is the constant parameter of piecewise integration, s1 is the pitch angle error comprehensive integral signal; k1, k2, k3, k4, k5, k6 are constant control parameters, and u1 is the pitch attitude comprehensive control signal; Step S40: Based on flight mission requirements or pitch angle error, set the desired overload signal; then install accelerometers on the UAV to measure the vertical acceleration, calculate the vertical overload signal, and compare it with the desired overload signal to obtain the overload error signal; then perform an odd-order transform to obtain the odd-order overload error signal; then perform a hybrid exponential root transformation on the overload error signal to obtain the exponential root overload error signal; finally, superimpose the overload error signal, the odd-order overload error signal, and the exponential root overload error signal to obtain the comprehensive overload error signal as follows: e g =c a1 e2+c a2 g2+c a3 g2; Where 'a' represents the vertical acceleration signal of the unmanned aerial vehicle measured by an accelerometer, and 'g' represents the acceleration due to gravity. For the desired overload signal set according to the flight mission or according to the pitch angle error, n y e1 is the vertical overload signal of the aircraft; e2 is the overload error signal; g1 is the odd-order overload error signal; ε a0 g1 is the constant parameter for the square root transformation, g2 is the square root signal of the overload error exponent; c a1 c a2 c a3 e is a constant superposition coefficient. g This is a comprehensive signal for overload error. Step S50: The overload error translation error signal is obtained by comparing the comprehensive overload error signal with the nonlinear translation signal of the overload error; then, odd-order transform and odd-order softening transform are performed respectively to obtain the odd-order transform signal and the odd-order softening transform signal of the overload error, which are then superimposed to obtain the nonlinear translation rate signal of the overload error; finally, a piecewise integration of cubic and linear hybrid anti-saturation is performed to obtain the nonlinear translation signal of the overload error as follows: e g1 (n)=e g (n)-e g0 (n); e g2 (n)=(e g (n)-e g0 (n)) 7 / 13 ; Where e g1 This is the overload translation error signal; e g2 For the odd-order transform signal of overload translation error; e g3 For the odd-order softened transform signal of overload translation error, e gd The nonlinear translation rate signal for overload error; e g0 b1 is the nonlinear translation signal of the overload error, and b1 is the constant piecewise parameter of the piecewise integral. Step S60: Solve the overload differential coefficient signal based on the overload error signal, and then solve the overload error mixed differential signal based on the nonlinear translation signal of the overload error, the comprehensive overload error signal, and the overload differential coefficient signal. Then, based on the overload error composite signal, a piecewise integration of cubic and linear anti-saturation is performed to obtain the overload error composite integrated signal. Finally, the overload error signal, the overload error mixed differential signal, the overload error nonlinear translation rate signal, the overload error composite signal, and the overload error nonlinear translation signal are superimposed to form the pitch overload composite control signal as follows: u2=k a1 e2+k a2 and 2d +k a3 s2+k a4 and gd +k a5 and g ; Where e 2z For overload differential coefficient signal, e 2d s1 is the mixed differential signal of overload error; b0 is the constant parameter of piecewise integration, s2 is the comprehensive integrated signal of overload error; k a1 k a2 k a3 k a4 k a5 k a6 u1 is a constant control parameter, and u2 is the pitch overload integrated control signal; Step S70: Set a switching threshold based on the pitch angle error signal. When the pitch angle error is less than the threshold, the pitch control quantity of the UAV is selected as the pitch attitude integrated control signal. When the pitch angle error is greater than the threshold, the pitch angle error is converted into an overload expectation signal, and the UAV pitch control quantity is selected as the pitch overload integrated control signal. This realizes the switching of the control law from attitude control to rapid overload control, achieving stable attitude tracking of the UAV pitch channel as follows: in For the overload expectation signal set according to the pitch angle error, a w The switching threshold is a constant parameter, k. w2 ε w1 k w1 is a constant conversion parameter, and u is the pitch control variable of the unmanned aerial vehicle.

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