A method for tracking angle of attack of unmanned aerial vehicle using adaptive observation

Abstract

The present invention provides a method for achieving precise and high-dynamic tracking of an aircraft's angle of attack by using an adaptive observation method. First, an angle of attack and force, and an angle of attack and angular rate observation and parallel nonlinear networks are established respectively. Then, an angle of attack observer and a pitch rate observer are established. The observation error drives the adaptive convergence of the weight parameters of the nonlinear network. Simultaneously, an advance correction network is designed based on the observation error to obtain an observation error correction signal, which is combined with the observation integral signal and the observation error nonlinear signal to form a sliding mode signal, thereby achieving sliding mode control of the observer. Simultaneously, an expected angle of attack value set according to a flight mission is compared with the angle of attack observation value to obtain an angle of attack error. Then, an inverse design method is used to calculate an aircraft rudder angle signal based on the output signal of the parallel nonlinear observation network, the error correction signal, and the error integral signal, thereby achieving high-precision and high-dynamic performance control of the aircraft's angle of attack.

Description

Technical Field

[0001] The present invention relates to the field of aircraft control, and in particular to an unmanned aerial vehicle attack angle tracking method using adaptive observation. Background Art

[0002] Since the angle of attack is the root cause of the forces and moments in the pitch channel of an aircraft, divergence is the primary cause of pitch channel instability. Therefore, angle of attack tracking and stability are crucial to aircraft control. Furthermore, angle of attack tracking capability is closely related to the quality of control tasks completed at all stages of the aircraft. Traditionally, when using inverse control to design aircraft angle of attack tracking, control is effective if the model is precisely known. However, due to the complex aerodynamic characteristics of high-speed aircraft motion, the accuracy of many starting parameters remains difficult to guarantee, even after wind tunnel testing. Some parameters inevitably have an error range exceeding 20%. Furthermore, many factors are not considered during modeling, resulting in errors caused by differentials and system uncertainties being multiplied throughout the inverse control process, especially for multi-stage series systems. This also makes parameter adjustment and selection for the entire inverse control process extremely difficult. Based on the above background reasons, the present invention proposes a method of using adaptive observation to adaptively observe the main dynamic characteristics of the aircraft, while ensuring the stable tracking of the entire observer by observing the control quantity; then, an inverse design of angle of attack tracking is performed on the observer system with a completely known structure, thereby indirectly achieving the angle of attack tracking of the aircraft. As a result, the present invention also has excellent dynamic performance of angle of attack tracking and control, and also makes the present invention have high engineering practical value.

[0003] It should be noted that the information disclosed in the above background technology section 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 ordinary technicians in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation, thereby overcoming the problem of low dynamic performance of the aircraft angle of attack control caused by defects in related technologies.

[0005] According to one aspect of the present invention, a method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation is provided, comprising the following five steps:

[0006] Step S10, setting the initial value of the angle of attack observation signal of the angle of attack observer to 0, introducing the rudder deflection angle signal of the aircraft rudder system into the angle of attack observer system, and setting the initial value of the angle of attack observation controller signal to 0, establishing the angle of attack and force observation parallel nonlinear network according to the angle of attack observation signal, and setting the initial value of the weight of the angle of attack and force observation network to a constant value, obtaining the output signal of the angle of attack and force observation parallel nonlinear network, and superimposing the pitch angle rate observation signal and the angle of attack observation controller signal and the rudder deflection angle signal to obtain the angle of attack rate observation signal; then performing integration to obtain the angle of attack observation signal; setting the pitch angle of the pitch angle rate observer to 0. The initial value of the elevation observation signal is 0, the rudder deflection angle signal of the aircraft rudder system is introduced into the pitch rate observer system, and the initial value of the pitch rate observation controller signal is set to 0. According to the angle of attack observation signal, an angle of attack and angular rate observation parallel nonlinear network is established, and the initial value of the weight of the angle of attack and angular rate observation network is set to a constant value to obtain the output signal of the angle of attack and angular rate observation parallel nonlinear network. Then, the pitch rate observation signal, the angle of attack observation signal, the pitch rate observation controller signal and the rudder deflection angle signal are superimposed to obtain the pitch acceleration observation signal; and then, the pitch rate observation signal is obtained by integration.

[0007] Step S20, install the angle of attack sensor, measure the aircraft angle of attack signal, and compare it with the angle of attack observation signal to obtain the angle of attack observation error signal; then integrate it to obtain the angle of attack observation error integral signal; then establish an advance correction network to obtain the angle of attack observation error advance correction signal; then according to the angle of attack observation error signal and the angle of attack observation signal, respectively solve the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network, and then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network in turn.

[0008] Step S30, install a pitch rate gyro, measure the pitch rate signal of the aircraft, and compare it with the pitch rate observation signal to obtain a pitch rate observation error signal; then integrate it to obtain a pitch rate observation error integral signal; then establish an advance correction network to obtain a pitch rate observation error advance correction signal; then, based on the pitch rate observation error signal and the angle of attack observation signal, respectively calculate the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network, and then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and angular rate observation network.

[0009] Step S40, forming an angle of attack observation error sliding mode signal based on the angle of attack observation error signal, the angle of attack observation error integral signal, the angle of attack observation error advance correction signal, and performing a nonlinear transformation on the angle of attack observation error signal; superimposing the nonlinear transformation of the angle of attack observation error sliding mode signal to obtain an angle of attack observation controller signal; forming a pitch angle rate observation error sliding mode signal based on the pitch angle rate observation error signal, the pitch angle rate observation error integral signal, the pitch angle rate observation error advance correction signal, and performing a nonlinear transformation on the pitch angle rate observation error signal; superimposing the nonlinear transformation of the pitch angle rate observation error sliding mode signal to obtain a pitch angle rate observation controller signal.

[0010] Step S50, according to the flight control task of the aircraft, set the expected angle of attack value, then compare the angle of attack observation signal with the expected angle of attack value to obtain an angle of attack error signal; then integrate to obtain an angle of attack error integral signal; then establish an advance correction network to obtain an angle of attack error advance correction signal; then superimpose the output signal of the angle of attack and force observation parallel nonlinear network, rudder angle signal, and angle of attack observation controller signal to obtain a pitch angle rate expected signal; then compare with the pitch angle rate observation signal to obtain a pitch angle rate error signal; then integrate to obtain a pitch angle rate error integral signal; then establish an advance correction network to obtain a pitch angle rate error advance correction signal; then superimpose the output signal of the angle of attack and angular rate observation parallel nonlinear network, rudder angle signal, and pitch angle rate observation controller signal to obtain a final rudder angle signal, thereby realizing that the angle of attack of the aircraft pitch channel tracks the expected angle of attack value and completes the flight control task of the aircraft.

[0011] In an exemplary embodiment of the present invention, the initial value of the angle of attack observation signal of the angle of attack observer is set to 0, the rudder deflection angle signal of the aircraft rudder system is introduced into the angle of attack observer system, and the initial value of the angle of attack observation controller signal is set to 0, according to the angle of attack observation signal, an angle of attack and force observation parallel nonlinear network is established, and the initial value of the weight of the angle of attack and force observation network is set to a constant value, the output signal of the angle of attack and force observation parallel nonlinear network is obtained, and the pitch angle rate observation signal and the angle of attack observation controller signal and the rudder deflection angle signal are superimposed to obtain the angle of attack rate observation signal; then, the angle of attack observation signal is obtained by integration; the pitch angle rate observation signal is set The initial value of the pitch observation signal of the device is 0, the rudder deflection angle signal of the aircraft rudder system is introduced into the pitch rate observer system, and the initial value of the pitch rate observation controller signal is set to 0, according to the angle of attack observation signal, an angle of attack and angular rate observation parallel nonlinear network is established, and the initial value of the weight of the angle of attack and angular rate observation network is set to a constant value, and the output signal of the angle of attack and angular rate observation parallel nonlinear network is obtained, and then the pitch rate observation signal, the angle of attack observation signal, the pitch rate observation controller signal and the rudder deflection angle signal are superimposed to obtain the pitch acceleration observation signal; and then the pitch rate observation signal is obtained by integration, including:

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[0018] in is the angle of attack observation signal, is the rudder angle signal, and its initial value is selected as 0; is the angle of attack observation controller signal, is a constant parameter of the observer; 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively; The output signal of the parallel nonlinear network is the angle of attack and force observation. is the pitch angle rate observation signal, is the angle of attack rate observation signal; is the pitch angle rate observation controller signal; according to the angle of attack observation signal, 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively; Observe the angle of attack and angular rate and output signals of the parallel nonlinear network; is the pitch angular acceleration observation signal; Indicates the integration of the time signal; is a constant parameter of the angle of attack observer; 、 is a constant parameter of the pitch rate observer.

[0019] In an exemplary embodiment of the present invention, an angle of attack sensor is installed to measure an aircraft angle of attack signal, and the signal is compared with the angle of attack observation signal to obtain an angle of attack observation error signal; the signal is then integrated to obtain an angle of attack observation error integral signal; an advance correction network is then established to obtain an angle of attack observation error advance correction signal; and a first weight update rate signal, a second weight update rate signal, a third weight update rate signal, a fourth weight update rate signal, and a fifth weight update rate signal of the angle of attack and force observation network are respectively calculated based on the angle of attack observation error signal and the angle of attack observation signal, and the signals are then integrated to obtain, in sequence, a first weight signal, a second weight signal, a third weight signal, a fourth weight signal, and a fifth weight signal of the angle of attack and force observation network.

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[0033] in is the aircraft angle of attack signal, is the angle of attack observation error signal; is the angle of attack observation error integral signal; is the differential operator of the transfer function of the lead correction network, 、 is the constant time parameter of the advance correction network; It is the advance correction signal of the angle of attack observation error; 、 、 、 Respectively solving the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively. 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively.

[0034] In an exemplary embodiment of the present invention, a pitch rate gyroscope is installed to measure the pitch rate signal of the aircraft, and the signal is compared with the pitch rate observation signal to obtain a pitch rate observation error signal; the signal is then integrated to obtain a pitch rate observation error integral signal; a lead correction network is then established to obtain a pitch rate observation error lead correction signal; and a first weight update rate signal, a second weight update rate signal, a third weight update rate signal, a fourth weight update rate signal, and a fifth weight update rate signal of the angle of attack and angular rate observation network are respectively calculated based on the pitch rate observation error signal and the angle of attack observation signal, and the signals are then integrated to obtain, in sequence, a first weight signal, a second weight signal, a third weight signal, a fourth weight signal, and a fifth weight signal of the angle of attack and angular rate observation network.

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[0048] is the pitch rate signal of the aircraft, is the pitch angle rate observation error signal; is the pitch angle rate observation error integral signal; It is the lead correction signal of the pitch angle rate observation error; 、 、 、 are the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively. 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively.

[0049] In an exemplary embodiment of the present invention, forming an angle of attack observation error sliding mode signal based on the angle of attack observation error signal, the angle of attack observation error integral signal, the angle of attack observation error lead correction signal, and performing a nonlinear transformation on the angle of attack observation error signal; superimposing the nonlinear transformation of the angle of attack observation error sliding mode signal to obtain an angle of attack observation controller signal; forming a pitch angle rate observation error sliding mode signal based on the pitch angle rate observation error signal, the pitch angle rate observation error integral signal, the pitch angle rate observation error lead correction signal, and performing a nonlinear transformation on the pitch angle rate observation error signal; and superimposing the nonlinear transformation of the pitch angle rate observation error sliding mode signal to obtain the pitch angle rate observation controller signal comprises:

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[0054] in is the sliding mode signal of the angle of attack observation error; is the angle of attack observation controller signal; is the pitch angle rate observation error sliding mode signal; is the pitch rate observation controller signal; 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 is a constant control parameter.

[0055] In an exemplary embodiment of the present invention, an angle of attack desired value is set according to a flight control mission of an aircraft, and then an angle of attack error signal is obtained by comparing the angle of attack observation signal with the angle of attack desired value; then an angle of attack error integral signal is obtained by integrating the angle of attack error integral signal; then an advance correction network is established to obtain an angle of attack error advance correction signal; then an angle of attack and force observation parallel nonlinear network output signal, a rudder angle signal, and an angle of attack observation controller signal are superimposed to obtain a pitch angle rate desired signal; then a pitch angle rate error signal is obtained by comparing the angle of attack and the pitch angle rate observation signal; then an angle of attack error integral signal is obtained by integrating the angle of attack error integral signal; then an advance correction network is established to obtain a pitch angle rate error advance correction signal; and then an angle of attack and angular velocity observation parallel nonlinear network output signal, a rudder angle signal, and a pitch angle rate observation controller signal are superimposed to obtain a final rudder angle signal.

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[0064] in is the expected value of the angle of attack, is the angle of attack error signal; is the integrated signal of the angle of attack error; It is the advance correction signal of angle of attack error; is the expected signal of pitch angle rate; is the pitch angle rate error signal; is the pitch angle rate error integral signal; is the pitch angle rate error advance correction signal; 、 、 、 、 、 is a constant control parameter, It is the rudder angle signal.

[0065] Beneficial effects

[0066] The present invention provides an unmanned aerial vehicle (UAV) angle-of-attack tracking method using adaptive observation. Its main innovations are as follows: First, based on the angle of attack that has the greatest impact on the dynamic performance and stability of the aircraft, a parallel nonlinear network for angle-of-attack and force observation, as well as a parallel nonlinear network for angle-of-attack and angular velocity observation, is established. This network weights are adaptively adjusted to effectively account for the uncertainty of the observer system and the modeling component, thereby significantly improving the adaptive and anti-interference capabilities of the entire angle-of-attack tracking system. Second, by establishing an observer system, the uncertainty of the aircraft model is transferred to the observer system, and sliding mode control of the observer is implemented using a measured error sliding mode signal. This allows the observer system to converge stably and handle model uncertainty, thereby improving the anti-interference capability of the entire system. Third, by tracking the angle of attack desired signal through the observer system, backstepping control is employed to precisely resolve the control backstepping recursion and stability issues. Conventional control methods struggle with the inversion system, which is the problem of the poorly processed differential signal caused by the uncertainty of the original system. However, by reconstructing the observer system, since the observer system is completely known, it is well-suited for backstepping control to achieve angle of attack tracking. In particular, backstepping allows for the use of rudder angle compensation to resolve the non-minimum phase problem of the force differential equation in the traditional control model, effectively completing the aircraft control task. Fourth, by establishing a lead correction network that uniformly introduces the lead correction signal of the error signal, sufficient damping is provided for the entire control system, improving stability. Furthermore, the overall control scheme is relatively consistent, facilitating engineering implementation.

[0067] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The accompanying drawings are incorporated into and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and it is clear that those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0069] Figure 1 This is a flow chart of a method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation provided by the present invention;

[0070] Figure 2 is the angle of attack observation signal of the method provided in the embodiment of the present invention (unit: degree);

[0071] Figure 3 is the pitch angle rate observation signal of the method provided in the embodiment of the present invention (unit: degrees per second);

[0072] Figure 4 is the aircraft angle of attack signal of the method provided in the embodiment of the present invention (unit: degrees);

[0073] Figure 5 is the angle of attack observation error signal of the method provided by the embodiment of the present invention (unit: degrees per second);

[0074] Figure 6 is the angle of attack observation error advance correction signal of the method provided by the embodiment of the present invention (unitless);

[0075] Figure 7 is the pitch rate signal of the aircraft according to the method provided in the embodiment of the present invention (unit: degrees per second);

[0076] Figure 8 is the pitch angle rate observation error signal of the method provided in the embodiment of the present invention (unit: degrees per second);

[0077] Figure 9 The pitch rate observation error advance correction signal (unitless) of the method provided in the embodiment of the present invention;

[0078] Figure 10 is the angle of attack observation controller signal of the method provided by the embodiment of the present invention (unitless);

[0079] Figure 11 is the pitch rate observation controller signal of the method provided in the embodiment of the present invention (without units of degrees);

[0080] Figure 12 is the angle of attack error signal of the method provided by the embodiment of the present invention (unit: degree);

[0081] Figure 13 is the rudder angle signal (unit: degree) of the method provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0082] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present invention will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present invention. However, those skilled in the art will appreciate that the technical solutions of the present invention may be practiced while omitting one or more of the specific details, or that other methods, components, devices, steps, etc. may be employed. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present invention.

[0083] The present invention provides a method for achieving precise and high-dynamic tracking of an aircraft angle of attack by adopting an adaptive observation method. First, an angle of attack and force, and an angle of attack and angular rate observation parallel nonlinear networks are established respectively. Then, an angle of attack observer and a pitch angle rate observer are established. The observation error drives the adaptive convergence of the weight parameters of the nonlinear network. At the same time, an advance correction network is designed based on the observation error to obtain an observation error correction signal. The signal is combined with the observation integral signal and the observation error nonlinear signal to form a sliding mode signal, thereby achieving sliding mode control of the observer. At the same time, an expected angle of attack value set according to a flight mission is compared with the angle of attack observation value to obtain an angle of attack error. Then, an inverse design method is used to reversely calculate an expected signal of the aircraft pitch angle rate based on the observation parallel nonlinear network and the rudder deflection angle signal. The signal is then compared with the aircraft pitch angle rate measurement signal to obtain a pitch angle rate error signal. The aircraft rudder deflection angle signal is further calculated based on the output signal of the observation parallel nonlinear network, the error correction signal, and the error integral signal, thereby achieving high-precision and high-dynamic performance control of the aircraft angle of attack.

[0084] Below, we will combine the Figure 1 The present invention provides a method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation, which is further explained and illustrated. Figure 1 As shown, the method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation includes the following steps:

[0085] Step S10, setting the initial value of the angle of attack observation signal of the angle of attack observer to 0, introducing the rudder deflection angle signal of the aircraft rudder system into the angle of attack observer system, and setting the initial value of the angle of attack observation controller signal to 0, establishing the angle of attack and force observation parallel nonlinear network according to the angle of attack observation signal, and setting the initial value of the weight of the angle of attack and force observation network to a constant value, obtaining the output signal of the angle of attack and force observation parallel nonlinear network, and superimposing the pitch angle rate observation signal and the angle of attack observation controller signal and the rudder deflection angle signal to obtain the angle of attack rate observation signal; then performing integration to obtain the angle of attack observation signal; setting the pitch angle of the pitch angle rate observer to 0. The initial value of the elevation observation signal is 0, the rudder deflection angle signal of the aircraft rudder system is introduced into the pitch rate observer system, and the initial value of the pitch rate observation controller signal is set to 0. According to the angle of attack observation signal, an angle of attack and angular rate observation parallel nonlinear network is established, and the initial value of the weight of the angle of attack and angular rate observation network is set to a constant value to obtain the output signal of the angle of attack and angular rate observation parallel nonlinear network. Then, the pitch rate observation signal, the angle of attack observation signal, the pitch rate observation controller signal and the rudder deflection angle signal are superimposed to obtain the pitch acceleration observation signal; and then, the pitch rate observation signal is obtained by integration.

[0086] Specifically, it can be decomposed into the following four steps. The first step is to set the initial value of the angle of attack observation signal of the angle of attack observer to 0. Based on the angle of attack observation signal, a parallel nonlinear network of angle of attack and force observation is established, and the initial weight values ​​of the angle of attack and force observation network are set to constant values. The output signal of the parallel nonlinear network of angle of attack and force observation is as follows:

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[0088] in is the angle of attack observation signal, The output signal of the parallel nonlinear network is the angle of attack and force observation. 、 、 、 、 are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively. is a constant parameter of the observer.

[0089] In the second step, the rudder angle signal of the aircraft rudder system is introduced into the angle of attack observer system, and the initial value of the angle of attack observation controller signal is set to 0. The angle of attack and the force observation parallel nonlinear network output signal, the pitch angle rate observation signal, the angle of attack observation controller signal and the rudder angle signal are superimposed to obtain the angle of attack rate observation signal. The angle of attack observation signal is then integrated to obtain the following:

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[0092] in is the rudder angle signal, and its initial value is selected as 0; is the angle of attack observation controller signal, is the pitch angle rate observation signal, is the angle of attack rate observation signal, is the angle of attack observation signal, Indicates the integration of the time signal; is a constant parameter of the angle of attack observer.

[0093] In the third step, based on the angle of attack observation signal, a parallel nonlinear network for angle of attack and angular rate observation is established, and the initial weight values ​​of the angle of attack and angular rate observation network are set to constant values. The output signal of the parallel nonlinear network for angle of attack and angular rate observation is as follows:

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[0095] in 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively; It is the output signal of the angle of attack and angular rate observation parallel nonlinear network.

[0096] The fourth step is to set the initial value of the pitch observation signal of the pitch rate observer to 0, introduce the rudder angle signal of the aircraft rudder system into the pitch rate observer system, and set the initial value of the pitch rate observation controller signal to 0. Based on the output signal of the angle of attack and angular rate observation parallel nonlinear network, the pitch rate observation signal, the angle of attack observation signal, the pitch rate observation controller signal and the rudder angle signal are superimposed to obtain the pitch acceleration observation signal; then, the pitch rate observation signal is integrated to obtain the following pitch rate observation signal:

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[0099] in is the pitch angle rate observation controller signal; according to the angle of attack observation signal, is the pitch angular acceleration observation signal; 、 is a constant parameter of the pitch rate observer.

[0100] Step S20, install the angle of attack sensor, measure the aircraft angle of attack signal, and compare it with the angle of attack observation signal to obtain the angle of attack observation error signal; then integrate it to obtain the angle of attack observation error integral signal; then establish an advance correction network to obtain the angle of attack observation error advance correction signal; then according to the angle of attack observation error signal and the angle of attack observation signal, respectively solve the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network, and then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network in turn.

[0101] Specifically, it can be broken down into the following three steps. The first step is to install the angle of attack sensor, measure the aircraft angle of attack signal, and compare it with the angle of attack observation signal to obtain the angle of attack observation error signal; then integrate it to obtain the angle of attack observation error integral signal as follows:

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[0104] in is the aircraft angle of attack signal, is the angle of attack observation error signal; is the integrated signal of the angle of attack observation error.

[0105] The second step is to establish an advance correction network and obtain the advance correction signal of the angle of attack observation error as follows:

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[0107] in is the differential operator of the transfer function of the lead correction network, 、 is the constant time parameter of the advance correction network; It is the advance correction signal of the angle of attack observation error.

[0108] In the third step, based on the angle of attack observation error signal and the angle of attack observation signal, the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network are respectively solved, and then integrated to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and force observation network in sequence as follows:

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[0119] in 、 、 、 Respectively solving the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively. 、 、 、 、 are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively. is a constant parameter.

[0120] Step S30, install a pitch rate gyro, measure the pitch rate signal of the aircraft, and compare it with the pitch rate observation signal to obtain a pitch rate observation error signal; then integrate it to obtain a pitch rate observation error integral signal; then establish an advance correction network to obtain a pitch rate observation error advance correction signal; then, based on the pitch rate observation error signal and the angle of attack observation signal, respectively calculate the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network, and then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and angular rate observation network.

[0121] Specifically, it can be broken down into the following three steps. The first step is to install a pitch rate gyro, measure the aircraft's pitch rate signal, and compare it with the pitch rate observation signal to obtain a pitch rate observation error signal; then integrate it to obtain a pitch rate observation error integral signal as follows:

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[0124] in is the pitch rate signal of the aircraft, is the pitch angle rate observation error signal; is the pitch angle rate observation error integral signal.

[0125] The second step is to establish an advance correction network and obtain the lead correction signal of the pitch rate observation error as follows:

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[0127] in It is the lead correction signal of the pitch angle rate observation error.

[0128] In the third step, based on the pitch angle rate observation error signal and the angle of attack observation signal, the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network are respectively calculated, and then integrated to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and angular rate observation network in sequence as follows:

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[0137] ;

[0138] ;

[0139] in 、 、 、 are the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively. 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively.

[0140] Step S30, forming an angle of attack observation error sliding mode signal based on the angle of attack observation error signal, the angle of attack observation error integral signal, the angle of attack observation error advance correction signal, and performing a nonlinear transformation on the angle of attack observation error signal; superimposing the nonlinear transformation of the angle of attack observation error sliding mode signal to obtain an angle of attack observation controller signal; forming a pitch angle rate observation error sliding mode signal based on the pitch angle rate observation error signal, the pitch angle rate observation error integral signal, the pitch angle rate observation error advance correction signal, and performing a nonlinear transformation on the pitch angle rate observation error signal; superimposing the nonlinear transformation of the pitch angle rate observation error sliding mode signal to obtain a pitch angle rate observation controller signal.

[0141] Specifically, it can be decomposed into the following four steps. The first step is to perform a nonlinear transformation on the angle of attack observation error signal, the angle of attack observation error integral signal, the angle of attack observation error advance correction signal, and the angle of attack observation error signal to form an angle of attack observation error sliding mode signal as follows:

[0142] ;

[0143] in is the sliding mode signal of the angle of attack observation error; 、 、 、 、 、 is a constant control parameter.

[0144] In the second step, the nonlinear transformation of the angle of attack observation error sliding mode signal is superimposed on the angle of attack observation error sliding mode signal to obtain the angle of attack observation controller signal as follows:

[0145] ;

[0146] in is the angle of attack observation controller signal; 、 、 is a constant control parameter.

[0147] In the third step, a nonlinear transformation is performed on the pitch angle rate observation error signal based on the pitch angle rate observation error signal, the pitch angle rate observation error integral signal, the pitch angle rate observation error lead correction signal, and the pitch angle rate observation error signal to form a pitch angle rate observation error sliding mode signal as follows:

[0148] ;

[0149] in is the pitch angle rate observation error sliding mode signal; 、 、 、 、 、 is a constant control parameter.

[0150] In the fourth step, based on the pitch angle rate observation error sliding mode signal, the nonlinear transformation of the pitch angle rate observation error sliding mode signal is superimposed to obtain the pitch angle rate observation controller signal as follows:

[0151] ;

[0152] in is the pitch rate observation controller signal; 、 、 is a constant control parameter.

[0153] Step S50, setting an expected angle of attack value according to the flight control task of the aircraft, then comparing the angle of attack observation signal with the expected angle of attack value to obtain an angle of attack error signal; then integrating to obtain an angle of attack error integral signal; then establishing an advance correction network to obtain an angle of attack error advance correction signal; then superimposing the angle of attack and force observation parallel nonlinear network output signal, rudder angle signal, and angle of attack observation controller signal to obtain a pitch angle rate expected signal; then comparing with the pitch angle rate observation signal to obtain a pitch angle rate error signal; then integrating to obtain a pitch angle rate error integral signal; then establishing an advance correction network to obtain a pitch angle rate error advance correction signal; then superimposing the angle of attack and angular velocity observation parallel nonlinear network output signal, rudder angle signal, and pitch angle rate observation controller signal to obtain a final rudder angle signal.

[0154] Specifically, it can be broken down into the following six steps. The first step is to set the expected angle of attack value according to the flight control mission of the aircraft, and then compare the angle of attack observation signal with the expected angle of attack value to obtain the angle of attack error signal; then integrate it to obtain the angle of attack error integral signal as follows:

[0155] ;

[0156] ;

[0157] in is the expected value of the angle of attack, is the angle of attack error signal; is the integrated signal of the angle of attack error.

[0158] The second step is to establish an advance correction network and obtain the angle of attack error advance correction signal as follows:

[0159] ;

[0160] in It is the advance correction signal of angle of attack error.

[0161] In the third step, the desired pitch rate signal is obtained by superimposing the attack angle error advance correction signal on the attack angle and force observation parallel nonlinear network output signal, the rudder angle signal, and the attack angle observation controller signal as follows:

[0162] ;

[0163] in is the expected signal of pitch angle rate; 、 、 is a constant control parameter.

[0164] In the fourth step, the pitch angle rate expected signal is compared with the pitch angle rate observation signal to obtain a pitch angle rate error signal; and then the pitch angle rate error integral signal is obtained by integrating the signal as follows:

[0165] ;

[0166] ;

[0167] in is the pitch angle rate error signal; is the pitch angle rate error integral signal.

[0168] The fifth step is to establish an advance correction network and obtain the pitch angle rate error advance correction signal as follows:

[0169] ;

[0170] in It is the pitch angle rate error lead correction signal.

[0171] Step 6: The pitch rate error leads the correction signal. The final rudder angle signal is obtained by superimposing the attack angle and angular rate observation parallel nonlinear network output signal, the rudder angle signal, and the pitch rate observation controller signal as follows:

[0172] ;

[0173] in 、 、 、 、 、 is a constant control parameter, The rudder deflection angle signal is used to track the angle of attack of the aircraft's pitch channel to the expected value of the angle of attack, thus completing the aircraft's flight control mission.

[0174] Case implementation and computer solution results analysis

[0175] In step S10, select , 、 , and the angle of attack observation signal is obtained as Figure 2 As shown; The pitch angle rate observation signal is as follows Figure 3 As shown;

[0176] In step S20, select 、 、 、 、 , install the angle of attack sensor and measure the aircraft angle of attack signal such as Figure 4 As shown, the angle of attack observation error signal is obtained as Figure 5 As shown; the angle of attack observation error advance correction signal is obtained as Figure 6 shown.

[0177] In step S30, a pitch rate gyroscope is installed to measure the pitch rate signal of the aircraft. Figure 7 As shown, the pitch angle rate observation error signal is obtained as Figure 8 As shown; the pitch angle rate observation error advance correction signal is obtained as Figure 9 shown.

[0178] In step S40, select 、 、 、 、 , , 、 、 , the angle of attack observation controller signal is obtained as Figure 10 As shown; the pitch angle rate observation controller signal is obtained as Figure 11 shown.

[0179] Step S50, setting 、 、 、 、 、 ; Set the expected angle of attack according to the flight control mission of the aircraft is -3 degrees, and the angle of attack error signal is obtained as Figure 12 As shown; The final rudder angle signal is as follows Figure 13 shown.

[0180] Depend on Figure 2 and Figure 4It can be seen that both the angle of attack observation signal and the angle of attack signal can quickly stabilize at the angle of attack expected signal -3 degrees, and Figure 13 It can be seen that the rudder angle signal does not exceed the actual physical limit of 30 degrees during the whole process, and the initial rudder angle signal is relatively large, which provides a good speed for the whole control. The rudder angle signal is smooth and has no vibration, which also makes the dynamic performance of the whole angle of attack control better. Figure 12 It can be seen that both the observation error signal and the angle of attack error signal can converge smoothly to 0, which makes the improved method of the present invention have good stability and reliability, and also makes the method provided by the present invention have high engineering practical value.

Claims

1. A method for tracking the angle of attack of an unmanned aerial vehicle using adaptive observation, characterized in that: The following steps are involved: Step S10, setting the initial value of the angle of attack observation signal of the angle of attack observer to 0, introducing the rudder deflection angle signal of the aircraft rudder system into the angle of attack observer system, and setting the initial value of the angle of attack observation controller signal to 0, establishing the angle of attack and force observation parallel nonlinear network according to the angle of attack observation signal, and setting the initial value of the weight of the angle of attack and force observation network to a constant value, obtaining the output signal of the angle of attack and force observation parallel nonlinear network, and superimposing the pitch angle rate observation signal and the angle of attack observation controller signal and the rudder deflection angle signal to obtain the angle of attack rate observation signal; then integrating to obtain the angle of attack observation signal; setting the pitch of the pitch angle rate observer The initial value of the observation signal is 0. The rudder deflection angle signal of the aircraft rudder system is introduced into the pitch rate observer system, and the initial value of the pitch rate observation controller signal is set to 0. According to the angle of attack observation signal, an angle of attack and angular rate observation parallel nonlinear network is established, and the initial value of the weight of the angle of attack and angular rate observation network is set to a constant value. The output signal of the angle of attack and angular rate observation parallel nonlinear network is obtained. Then, the pitch rate observation signal, the angle of attack observation signal, the pitch rate observation controller signal and the rudder deflection angle signal are superimposed to obtain the pitch acceleration observation signal. Then, the pitch rate observation signal is obtained by integration as follows: ； ； ； ； ； ； in is the angle of attack observation signal, is the rudder angle signal, and its initial value is selected as 0; is the angle of attack observation controller signal, is a constant parameter of the observer; 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively; The output signal of the attack angle and force observation parallel nonlinear network, is the pitch angle rate observation signal, is the angle of attack rate observation signal; is the pitch angle rate observation controller signal; according to the angle of attack observation signal, 、 、 、 、 They are the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively; Observe the angle of attack and angular rate and output signals of the parallel nonlinear network; is the pitch angular acceleration observation signal; Indicates the integration of the time signal; is a constant parameter of the angle of attack observer; 、 is the constant parameter of the pitch rate observer; Step S20: Install an angle of attack sensor, measure the aircraft angle of attack signal, and compare it with the angle of attack observation signal to obtain an angle of attack observation error signal; then integrate it to obtain an angle of attack observation error integral signal; then establish an advance correction network to obtain an angle of attack observation error advance correction signal; then, based on the angle of attack observation error signal and the angle of attack observation signal, respectively calculate the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network, and then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and force observation network, as follows: ； ； ； ； ； ； ； ； ； ； ； ； ； in is the aircraft angle of attack signal, is the angle of attack observation error signal; is the angle of attack observation error integral signal; is the differential operator of the transfer function of the lead correction network, 、 is the constant time parameter of the advance correction network; It is the advance correction signal of the angle of attack observation error; 、 、 、 Respectively solving the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and force observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and force observation network respectively; Step S30: Install a pitch rate gyro, measure the pitch rate signal of the aircraft, and compare it with the pitch rate observation signal to obtain a pitch rate observation error signal; then integrate it to obtain a pitch rate observation error integral signal; then establish an advance correction network to obtain a pitch rate observation error advance correction signal; then, based on the pitch rate observation error signal and the angle of attack observation signal, respectively calculate the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network; then integrate them to obtain the first weight signal, the second weight signal, the third weight signal, the fourth weight signal, and the fifth weight signal of the angle of attack and angular rate observation network, as follows: ； ； ； ； ； ； ； ； ； ； ； ； ； in is the pitch rate signal of the aircraft, is the pitch angle rate observation error signal; is the pitch angle rate observation error integral signal; It is the lead correction signal of the pitch angle rate observation error; 、 、 、 are the first weight update rate signal, the second weight update rate signal, the third weight update rate signal, the fourth weight update rate signal, and the fifth weight update rate signal of the angle of attack and angular rate observation network; 、 、 、 、 are constant parameters, which are used to adjust the convergence speed of the first weight signal, the second weight signal, the third weight signal, the fourth weight signal and the fifth weight signal of the angle of attack and angular rate observation network respectively. is a constant parameter; Step S40: performing a nonlinear transformation on the angle of attack observation error signal, the angle of attack observation error integral signal, the angle of attack observation error lead correction signal, and the angle of attack observation error signal to form an angle of attack observation error sliding mode signal; superimposing the nonlinear transformation of the angle of attack observation error sliding mode signal to obtain an angle of attack observation controller signal; performing a nonlinear transformation on the pitch angle rate observation error signal, the pitch angle rate observation error integral signal, the pitch angle rate observation error lead correction signal, and the pitch angle rate observation error signal to form a pitch angle rate observation error sliding mode signal; superimposing the nonlinear transformation of the pitch angle rate observation error sliding mode signal to obtain a pitch angle rate observation controller signal as follows: ； ； ； ； in is the sliding mode signal of the angle of attack observation error; is the angle of attack observation controller signal; is the pitch angle rate observation error sliding mode signal; is the pitch rate observation controller signal; 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 is a constant control parameter; Step S50, according to the flight control task of the aircraft, set the expected angle of attack value, then compare the angle of attack observation signal with the expected angle of attack value to obtain an angle of attack error signal; then integrate to obtain an angle of attack error integral signal; then establish an advance correction network to obtain an angle of attack error advance correction signal; then superimpose the output signal of the angle of attack and force observation parallel nonlinear network, the rudder angle signal, and the angle of attack observation controller signal to obtain a pitch angle rate expected signal; then compare with the pitch angle rate observation signal to obtain a pitch angle rate error signal; then integrate to obtain a pitch angle rate error integral signal; then establish an advance correction network to obtain a pitch angle rate error advance correction signal; then superimpose the output signal of the angle of attack and angular rate observation parallel nonlinear network, the rudder angle signal, and the pitch angle rate observation controller signal to obtain a final rudder angle signal, thereby achieving the tracking of the angle of attack of the aircraft pitch channel to the expected angle of attack value, and completing the flight control task of the aircraft as follows: ； ； ； ； ； ； ； ； in is the expected value of the angle of attack, is the angle of attack error signal; is the integrated signal of the angle of attack error; It is the advance correction signal of angle of attack error; is the expected signal of pitch angle rate; is the pitch angle rate error signal; is the pitch angle rate error integral signal; is the pitch angle rate error advance correction signal; 、 、 、 、 、 is a constant control parameter.

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