Aircraft attitude tracking control method based on interference observer and interference utilization

Abstract

The invention belongs to the field of aircraft control system design, provides an aircraft attitude tracking control method based on a disturbance observer and disturbance utilization, solves the problem of aircraft attitude tracking control, and comprises the following steps: step 1, establishing an aircraft attitude motion equation and obtaining a state space equation; 2, designing a cascade interference observer to observe the lumped interference of the system; and step 3, designing an attitude tracking control law based on the interference observer and interference utilization based on a backstepping method and in combination with a lumped interference observation value obtained by the cascade interference observer. The method is applied to aircraft attitude tracking control.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aircraft control system design, and particularly relates to an aircraft attitude tracking control method based on disturbance observer and disturbance utilization. BACKGROUND

[0002] Aircraft has important strategic significance and broad application prospects in the civil field: on the one hand, aircraft, with the advantages of fast speed, large airspace, long range and little influence of terrain, is becoming the core carrier of various emerging civil scenarios such as urban air traffic, regional aviation logistics, emergency patrol and rescue, and is the key direction of global aviation industry layout; on the other hand, the application of reusable flight platforms can significantly reduce operating costs and improve use efficiency, and is an important support for realizing a green and efficient aviation transportation system in the future. Aircraft attitude control technology, as a key link to ensure its smooth operation and precise control, is increasingly valued. Compared with traditional aircraft, the dynamic system of modern civil aircraft has the characteristics of strong coupling, strong nonlinearity and strong uncertainty. Traditional control techniques mostly select conservative control methods for these problems. These control methods have complex structure, are prone to input saturation problems, have slow response speed and low control performance, and have high requirements for servo mechanisms.

[0003] Therefore, it has become a current problem to be solved to carry out tracking control research on aircraft attitude systems and explore attitude control methods with low conservativeness and high adaptability. SUMMARY

[0004] The application provides an aircraft attitude tracking control method based on disturbance observer and disturbance utilization to realize the task of aircraft attitude tracking control. The control method has important theoretical value and engineering significance.

[0005] The aircraft attitude tracking control method based on disturbance observer and disturbance utilization includes the following design steps:

[0006] Step one, establishing an aircraft attitude motion equation and obtaining a state space equation;

[0007] Step two, designing a cascaded disturbance observer to observe the lumped disturbance of the system;

[0008] Step three, based on the backstepping method and combined with the lumped disturbance observation value obtained by the cascaded disturbance observer, designing an attitude tracking control law based on disturbance observer and disturbance utilization.

[0009] The application has the beneficial effects compared with the prior art:

[0010] The method solves the problem of slow convergence of the attitude system compared with the attitude control method based on the disturbance observer, and solves the problem of chattering of the system after entering the steady state compared with the attitude control method based on the traditional disturbance utilization.

[0011] The method is clear and simple in the design process, and is more flexible and convenient, and is more practical in actual engineering.

[0012] A kind of cascade disturbance observer is designed to observe the lumped disturbance of the attitude angle channel and the attitude angle rate channel, and the observation accuracy can be improved with the increase of cascade number. The existing attitude control method based on disturbance utilization often adopts the strategy of complete utilization or complete suppression when dealing with lumped disturbance, which will bring larger chattering after the attitude angle enters the steady state, and has adverse effects on the actuator.

[0013] The method introduced by the application introduces the disturbance action function, which can change the disturbance utilization rate based on the attitude tracking error, so as to effectively suppress the disturbance in the steady state, and has practical value in engineering.

[0014] The application will be further described below in combination with the drawings and embodiments: DESCRIPTION OF DRAWINGS

[0015] Figure 1 The application is based on the flight vehicle attitude tracking control flow chart of disturbance observer and disturbance utilization;

[0016] Figure 2 The application is based on the disturbance utilization process chart of yaw angle channel;

[0017] Figure 3 The application is based on the control input curve chart;

[0018] Figure 4 The application is based on the flight vehicle attitude angle change curve chart. DETAILED DESCRIPTION

[0019] The embodiments of the technical scheme of the application will be described in detail below in combination with the drawings. Unless otherwise specified, the technical terms or scientific terms used in the application are the usual meanings understood by the skilled in the art.

[0020] Specific embodiment one: refer to Figure 1 The flight vehicle attitude tracking control method based on disturbance observer and disturbance utilization provided by the embodiment is realized according to the following steps:

[0021] Step one, establish the flight vehicle attitude motion equation and obtain the state space equation;

[0022] Step two, design a cascade disturbance observer to observe the lumped disturbance of the system;

[0023] Step three, based on the backstepping method, and combined with the lumped disturbance observation value obtained by the cascade disturbance observer, the attitude tracking control law based on the disturbance observer and disturbance utilization is designed.

[0024] Specific implementation method two: the difference between this implementation method and specific implementation method one is that the specific process of step one is:

[0025] Establish the mathematical model of the aircraft attitude tracking control problem: considering the aircraft attitude tracking control situation, the flight attitude motion equation can be established as:

[0026] (1)

[0027] Among them, and , is the pitch angle of the aircraft, is the yaw angle of the aircraft, is the roll angle of the aircraft, is the roll angle rate of the aircraft, is the yaw angle rate of the aircraft, is the pitch angle rate of the aircraft, and are the unmodeled parts of the attitude angle channel and the attitude angle rate channel respectively, and the system matrix , , and are defined as follows:

[0028] (2)

[0029] Among them, are the moments of inertia of the aircraft in the body coordinate system axis respectively.

[0030] The control moment can be written as follows:

[0031] (3)

[0032] Among them, is the control input, is the right elevator deflection angle of the aircraft, is the left elevator deflection angle of the aircraft, is the rudder deflection angle of the aircraft, and are defined as

[0033] (4)

[0034] Among them, is the dynamic pressure, is the characteristic area of the aircraft, is the lateral characteristic length, is the longitudinal characteristic length, is the aircraft velocity, are the aerodynamic coefficients of the aircraft, respectively, is is a strongly nonlinear function defined as:

[0035] (5)

[0036] Considering that the system is subject to parameter perturbations and external disturbances, the model uncertainty is defined as:

[0037] (6)

[0038] where is the nominal value, and is the model uncertainty.

[0039] Finally, the attitude system (1) can be written in the following form:

[0040] (7)

[0041] (8)

[0042] where and are the lumped disturbances of the attitude angle channel and the attitude angular rate channel, respectively, and the system matrices , and are defined as:

[0043] (9)

[0044] The following assumptions are given for the above system: it is assumed that the derivatives of the disturbances and are bounded, i.e., satisfy:

[0045] (10)

[0046] where and are known positive constants.

[0047] Specific implementation three: this implementation is further limited: the specific process of step two of designing a cascaded disturbance observer to observe the lumped disturbance of the system is:

[0048] Step 2.1: Design a cascaded disturbance observer;

[0049] For attitude control systems (7) and (8), a cascaded disturbance observer of the following form is designed.

[0050] (11)

[0051] and

[0052] (12)

[0053] in, , ; and These are the lumped disturbance estimates for the attitude angle channel and the attitude angular rate channel, respectively. and As an auxiliary variable; , , , , , , , , , , and .

[0054] The observation error can then be written as:

[0055] (13)

[0056] Step 2.2: Verification and convergence

[0057] Attitude control system and It can be written in the following general form:

[0058] (14)

[0059] in, or , This is the lumped interference of the system. Therefore, a cascaded interference observer... and It can be written in the following form:

[0060] (15)

[0061] in, , , , , , and .

[0062] The observer error system is as follows:

[0063] (16)

[0064] in:

[0065] (17)

[0066] Applying the constant variation formula to system (16) yields:

[0067] (18)

[0068] because If it is a Hurwitz matrix, then when hour, The value is determined by Decision. Due to:

[0069] (19)

[0070] When aggregate interference The condition of equation (10) must be satisfied, that is, there exists a positive definite constant. Make This holds true, and we can obtain the following from equations (18) and (19):

[0071] (20)

[0072] Ultimately obtain

[0073] (twenty one)

[0074] Right now and .

[0075] The above steps verify that the designed cascaded interference observer for the attitude angle channel and attitude angular rate channel can achieve convergence of observation errors.

[0076] Specific Implementation Method Four: This implementation method further specifies that the specific process of step three is as follows:

[0077] Step 3.1: Design the aircraft attitude control law based on the disturbance observer

[0078] Based on the backstepping method, the following form of aircraft attitude control law based on a disturbance observer is designed:

[0079] (twenty two)

[0080] in, , Attitude angle tracking error , The desired attitude angle and attitude angular rate tracking error are given. , For virtual control laws, and The results were obtained by cascaded interference observers (11) and (12), respectively.

[0081] Step 3.2: Design the interference characteristic index and interference action function

[0082] For attitude systems (7) and (8), the disturbance characteristic index is defined. and It can be in the following form:

[0083] (twenty three)

[0084] in, Indicates the attitude angle channel interference characteristic index. Indicates the interference characteristic index of the attitude angular rate channel;

[0085] , .

[0086] For attitude systems (7) and (8), the disturbance action function is defined as follows: and ,in:

[0087] (twenty four)

[0088] (25)

[0089] in, , and For parameters to be set, and Defined by equation (22), and Defined by the interference characteristic index (23).

[0090] Step 3.3: Design the aircraft attitude control law based on the interference observer and interference exploitation.

[0091] Combining equations (23), (24), and (25), an interference function is added to equation (22). and Design an attitude control law based on a disturbance observer and disturbance exploitation:

[0092] (26)

[0093] in, , and Observed by cascaded interference observers (11) and (12), respectively.

[0094] Indicates the gain of the attitude angle channel controller. Indicates the gain of the attitude angular rate channel controller;

[0095] The observer parameters are set as follows:

[0096] (27)

[0097] Indicates the gain of the attitude angle channel interference observer; Indicates the gain of the attitude angular rate channel interference observer;

[0098] Step 3.4: Verify attitude tracking error convergence

[0099] Choose the Lyapunov function as:

[0100] (28)

[0101] Its derivative can be written as:

[0102] (29)

[0103] This represents the observation error of the interference observer in the attitude angle channel. The observation error of the interference observer represents the attitude angle channel rate.

[0104] From equations (24) and (25), it can be seen that, and satisfy and .when hour, Further ,when hour, Further ,Right now:

[0105] Established. Similarly, Therefore, equation (29) can be further written as:

[0106] (30)

[0107] in:

[0108] (31)

[0109] because , For positive constants, equation (30) can be further written as:

[0110] (32)

[0111] in, , It is a diagonal matrix.

[0112] The above analysis shows that if ,but Always in the collection within; if ,but Exponential convergence to set It is worth noting that the parameters With gain , , , and (in The correlation is positive. Therefore, by choosing a sufficiently large correlation gain, the error bound is... It can be adjusted to an arbitrarily small value, thereby ensuring attitude tracking error. It converges to an arbitrary small neighborhood of zero.

[0113] Example

[0114] Assuming the initial altitude of the aircraft initial velocity ,initial Moment of inertia , and Initial attitude angle , and The remaining states are initially set to 0. The parameters of the cascaded interference observers (11) and (12) are selected as follows: The parameters of the interference functions (24) and (25) are selected as follows: and The parameters in equation (26) are selected as follows: and The model uncertainty parameter is selected as follows: , and Unmodeled interference and Selected as:

[0115] (33)

[0116] in, .

[0117] Consider an aircraft performing desired attitude command tracking in the following form.

[0118] (34).

[0119] Figure 2 The process of interference utilization in the yaw angle channel during the attitude tracking control of the aircraft was recorded. It can be seen that when the lumped interference in the yaw angle channel is conducive to the convergence of the attitude system, the interference action function changes with the yaw angle tracking error, thereby changing the degree of utilization of the beneficial interference. Figure 2 (a) is a graph showing the variation of interference observations in the yaw angle channel. Figure 2 (b) is a graph showing the variation of yaw angle tracking error. Figure 3 (c) yaw angle channel interference utilization variation curve). Figure 3 The changes in control input during the aircraft attitude tracking control process were recorded, and the right elevator deflection angle can be observed. Figure 3 (a) shown), left elevator deflection ( Figure 3 (b) and rudder deflection ( Figure 4 (c) As shown, it can quickly exit the saturation state during attitude tracking control, achieve attitude tracking control with a lower control quantity, and avoid the problem of rudder deflection angle chattering caused by interference during steady state. Figure 4 The curves recording the changes in the aircraft's desired attitude angle and actual attitude angle were recorded. Figure 4 (a) Pitch angle variation curve, Figure 4 (b) is a graph showing the change in yaw angle. ​ (c) The roll angle variation curve shows that the aircraft can track the desired attitude angle in a relatively short time. This indicates that the aircraft attitude tracking control method based on interference observer and interference utilization proposed in this invention is very effective for aircraft attitude tracking control.

[0120] This application has been disclosed above with preferred embodiments, but it is not intended to limit this application. Any person skilled in the art can make some changes or modifications to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the technical solution of this application, and all such modifications and modifications are within the scope of the technical solution of this application.

Claims

1. An aircraft attitude tracking control method based on disturbance observer and disturbance utilization, characterized in that: The following steps are implemented: Step one, establish the aircraft attitude motion equation and get the state space equation; Step two, design a cascade disturbance observer to observe the lumped disturbance of the system; Step three, based on the backstepping method, combined with the lumped disturbance observation value obtained by the cascade disturbance observer, design an attitude tracking control law based on disturbance observer and disturbance utilization.

2. The aircraft attitude tracking control method based on disturbance observer and disturbance utilization according to claim 1, characterized in that: The specific process of step one is: Establish the mathematical model of the aircraft attitude tracking control problem: considering the aircraft attitude tracking control situation, the flight attitude motion equation can be established as: （1） wherein: and , is the pitch angle of the aircraft, is the yaw angle of the aircraft, is the roll angle of the aircraft, is the roll angle rate of the aircraft, is the yaw angle rate of the aircraft, is the pitch angle rate of the aircraft, and are the unmodeled parts of the attitude angle channel and the attitude angle rate channel, respectively, the system matrix , , and are defined as follows: （2） wherein are the body coordinates of the aircraft the moment of inertia of the axis Control torque may be written as follows: （3） wherein is the control input, is the aircraft right elevator deflection angle, is the aircraft left elevator deflection angle, is the aircraft rudder deflection angle, and is defined as: （4） wherein is the dynamic pressure, is the characteristic area of the aircraft, is the lateral characteristic length, is the longitudinal characteristic length, is the speed of the aircraft, are the aerodynamic coefficients of the aircraft, respectively, is is a strongly nonlinear function of the form （5） Considering that the system is subject to parameter perturbation and external disturbance, the model uncertainty is defined as: （6） wherein, are nominal values, and is a model uncertainty; Finally, the attitude system (1) is written in the following form （7） （8） where and are the lumped disturbances of the attitude angle channel and the attitude angle rate channel, respectively, the system matrix , and are defined as: （9） The following assumptions are made for the system described above: it is assumed that the disturbances and have bounded derivatives, i.e. satisfy: （10） wherein with is a known constant.

3. The aircraft attitude tracking control method based on disturbance observer and disturbance utilization according to claim 2, characterized in that: The specific process of step two is: Step 2.1: Design a cascade disturbance observer; For attitude systems (7) and (8), design a cascade disturbance observer in the following form: （11） And （12） wherein , ; and are lumped disturbance estimates for the attitude angle channel and the attitude angle rate channel, respectively; and are auxiliary variables; , , , , , , , , , , and ; Then the observation error can be written as: （13） Step 2.2: Verification and convergence The attitude control system (7) and (8) can be written in the following general form: （14） where or , is the aggregate interference of the system, thus the cascaded interference observers (11) and (12) can be written as follows: （15） wherein , , , , , and ; The observer error system is: （16） Where: （17） Apply the constant variable formula to system (16) to get: （18） Because is a Hurwitz matrix, then when , the value of is determined by since: （19） When the aggregate interference satisfies condition (10), i.e., there exists a positive constant such that is established, from equations (18) and (19): （20） Finally, we get （21） That is and ; It is verified that the designed cascade disturbance observer of the attitude angle channel and the attitude angular rate channel can realize the convergence of the observation error.

4. The aircraft attitude tracking control method based on disturbance observer and disturbance utilization according to claim 3, characterized in that: The specific process of step three is: Step 3.1: Design an aircraft attitude control law based on disturbance observer Based on the backstepping method, design an aircraft attitude control law based on disturbance observer in the following form: （22） wherein , , the attitude angle tracking error , is the desired attitude angle, the attitude angle rate tracking error , is a virtual control law, and are respectively The cascade disturbance observer (11) and (12) observes that Step 3.2: Design disturbance characteristic index and disturbance action function For the attitude systems (7) and (8), define the disturbance characteristic index and in the form （23） wherein denotes the attitude angle channel interference characteristic index, denotes the attitude angle rate channel interference characteristic index; ， ； For the attitude systems (7) and (8), the disturbance action function is defined as and where: （24） （25） wherein , and are parameters to be set, and are defined by equation (22), and are defined by the interference characteristic index (23); Step 3.3: Design an aircraft attitude control law based on disturbance observer and disturbance utilization: Combining equations (23), (24) and (25), the interference function in equation (22) is increased and , a pose control law based on interference observer and interference utilization is designed: （26） wherein , and are observed by the concatenated disturbance observers (11) and (12), respectively, represents the attitude angle channel controller gain, represents the attitude angular rate channel controller gain; The observer parameters are set as: （27） represents the attitude angle channel disturbance observer gain; represents the attitude angle rate channel disturbance observer gain; Step 3.4: Verify pose tracking error convergence The Lyapunov function is selected as: （28） Its derivative is written as: （29） an observation error of the disturbance observer representing the attitude angle channel, an observation error of the disturbance observer representing the attitude angle channel rate; From equations (24) and (25), and satisfying and when , further have when , further have i.e. established, similarly, established, therefore, equation (29) is further written as: （30） Where: （31） In , is a positive number, equation (30) is further written as: （32） wherein , is a diagonal matrix; If , then is always in the set ; if , then exponentially converges to the set .

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